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Sample records for seasonal ice zone

  1. Contrasts in Sea Ice Deformation and Production in the Arctic Seasonal and Perennial Ice Zones

    NASA Technical Reports Server (NTRS)

    Kwok, K.

    2006-01-01

    Four years (1997-2000) of RADARSAT Geophysical Processor System (RGPS) data are used to contrast the sea ice deformation and production regionally, and in the seasonal (SIZ) and perennial (PIZ) ice zones. Ice production is of seasonal ice in openings during the winter. Three-day estimates of these quantities are provided within Lagrangian elements initially 10 km on a side. A distinct seasonal cycle is seen in both zones with these estimates highest in the late fall and with seasonal minimums in the midwinter. Regional divergence over the winter could be up to 30%. Spatially, the highest deformation is seen in the SIZ north of coastal Alaska. Both ice deformation and production are higher in the SIZ: deformation-related ice production in the SIZ (approx.0.5 m) is 1.5-2.3 times that of the PIZ (approx.0.3 m): this is connected to ice strength and thickness. Atmospheric forcing and boundary layer structure contribute to only the seasonal and interannual variability. Seasonal ice growth in ice fractures accounts for approx.25-40% of the total ice production of the Arctic Ocean. Uncertainties in these estimates are discussed. By itself, this deformation-ice production relationship could be considered a negative feedback when thickness is perturbed. However, the overall effect on ice production in the face of increasing seasonal and thinner/weaker ice coverage could be modified by local destabilization of the water column promoting overturning of warmer water due to increased brine rejection; and the upwelling of the pynocline associated with increased occurrence of large shear motion in sea ice. Divergence is shown to be negligibly correlated to cyclonic motion in summer and winter in both ice zones.

  2. Contrasts in Sea Ice Formation and Production in the Arctic Seasonal and Perennial Ice Zones

    NASA Technical Reports Server (NTRS)

    Kwok, R.

    2006-01-01

    Four years (1997-2000) of RADARSAT Geophysical Processor System (RGPS) data are used to contrast the sea ice deformation and production regionally, and in the seasonal (SIZ) and perennial (PIZ) ice zones. Ice production is of seasonal ice in openings during the winter. 3-day estimates of these quantities are provided within Lagrangian elements initially 10 km on a side. A distinct seasonal cycle is seen in both zones with these estimates highest in the late fall and with seasonal minimums in the mid-winter. Regional divergence over the winter could be up to 30%. Spatially, the highest deformation is in the SIZ north of coastal Alaska. Both ice deformation and production are higher in the SIZ: deformation-related ice production in the SIZ (approx.0.5 m) is 1.5-2.3 times that of the PIZ (approx.0.3 m) - this is connected to ice strength and thickness. Atmospheric forcing and boundary layer structure contribute to only the seasonal and interannual variability. Seasonal ice growth in ice fractures accounts for approx.25-40% of the total ice production of the Arctic Ocean. By itself, this deformation-ice production relationship could be considered a negative feedback when thickness is perturbed. However, the overall effect on ice production in the face of increasing seasonal and thinner/weaker ice coverage could be modified by: local destabilization of the water column promoting overturning of warmer water due to increased brine rejection; and, the upwelling of the pynocline associated with increased occurrence of large shear motion in sea ice.

  3. A microwave technique for mapping ice temperature in the Arctic seasonal sea ice zone

    SciTech Connect

    St. Germain, K.M.; Cavalieri, D.J.

    1997-07-01

    A technique for deriving ice temperature in the Arctic seasonal sea ice zone from passive microwave radiances has been developed. The algorithm operates on brightness temperatures derived from the Special Sensor Microwave/Imager (SSM/I) and uses ice concentration and type from a previously developed thin ice algorithm to estimate the surface emissivity. Comparisons of the microwave derived temperatures with estimates derived from infrared imagery of the Bering Strait yield a correlation coefficient of 0.93 and an RMS difference of 2.1 K when coastal and cloud contaminated pixels are removed. SSM/I temperatures were also compared with a time series of air temperature observations from Gambell on St. Lawrence Island and from Point Barrow, AK weather stations. These comparisons indicate that the relationship between the air temperature and the ice temperature depends on ice type.

  4. Characteristics of Arctic Ocean ice determined from SMMR data for 1979 - Case studies in the seasonal sea ice zone

    NASA Technical Reports Server (NTRS)

    Anderson, M. R.; Crane, R. G.; Barry, R. G.

    1985-01-01

    Sea ice data derived from the Scanning Multichannel Microwave Radiometer are examined for sections of the Arctic Ocean during early summer 1979. The temporary appearance of spuriously high multiyear ice fractions in the seasonal ice zones of the Kara and Barents Seas is a result of surface melt phenomena and the relative responses of the different channels to these effects. These spurious signatures can provide early identification of melt onset and additional information on surface characteristics.

  5. Aerial Surveys of the Beaufort Sea Seasonal Ice Zone in 2012-2014

    NASA Astrophysics Data System (ADS)

    Dewey, S.; Morison, J.; Andersen, R.; Zhang, J.

    2014-12-01

    Seasonal Ice Zone Reconnaissance Surveys (SIZRS) of the Beaufort Sea aboard U.S. Coast Guard Arctic Domain Awareness flights were made monthly from May 2012 to October 2012, June 2013 to August 2013, and June 2014 to October 2014. In 2012 sea ice extent reached a record minimum and the SIZRS sampling ranged from complete ice cover to open water; in addition to its large spatial coverage, the SIZRS program extends temporal coverage of the seasonal ice zone (SIZ) beyond the traditional season for ship-based observations, and is a good set of measurements for model validation and climatological comparison. The SIZ, where ice melts and reforms annually, encompasses the marginal ice zone (MIZ). Thus SIZRS tracks interannual MIZ conditions, providing a regional context for smaller-scale MIZ processes. Observations with Air eXpendable CTDs (AXCTDs) reveal two near-surface warm layers: a locally-formed surface seasonal mixed layer and a layer of Pacific origin at 50-60m. Temperatures in the latter differ from the freezing point by up to 2°C more than climatologies. To distinguish vertical processes of mixed layer formation from Pacific advection, vertical heat and salt fluxes are quantified using a 1-D Price-Weller-Pinkel (PWP) model adapted for ice-covered seas. This PWP simulates mixing processes in the top 100m of the ocean. Surface forcing fluxes are taken from the Marginal Ice Zone Modeling and Assimilation System MIZMAS. Comparison of SIZRS observations with PWP output shows that the ocean behaves one-dimensionally above the Pacific layer of the Beaufort Gyre. Despite agreement with the MIZMAS-forced PWP, SIZRS observations remain fresher to 100m than do outputs from MIZMAS and ECCO.2. The shapes of seasonal cycles in SIZRS salinity and temperature agree with MIZMAS and ECCO.2 model outputs despite differences in the values of each. However, the seasonal change of surface albedo is not high enough resolution to accurately drive the PWP. Use of ice albedo

  6. A Comparison of Sea Ice Type, Sea Ice Temperature, and Snow Thickness Distributions in the Arctic Seasonal Ice Zones with the DMSP SSM/I

    NASA Technical Reports Server (NTRS)

    St.Germain, Karen; Cavalieri, Donald J.; Markus, Thorsten

    1997-01-01

    Global climate studies have shown that sea ice is a critical component in the global climate system through its effect on the ocean and atmosphere, and on the earth's radiation balance. Polar energy studies have further shown that the distribution of thin ice and open water largely controls the distribution of surface heat exchange between the ocean and atmosphere within the winter Arctic ice pack. The thickness of the ice, the depth of snow on the ice, and the temperature profile of the snow/ice composite are all important parameters in calculating surface heat fluxes. In recent years, researchers have used various combinations of DMSP SSMI channels to independently estimate the thin ice type (which is related to ice thickness), the thin ice temperature, and the depth of snow on the ice. In each case validation efforts provided encouraging results, but taken individually each algorithm gives only one piece of the information necessary to compute the energy fluxes through the ice and snow. In this paper we present a comparison of the results from each of these algorithms to provide a more comprehensive picture of the seasonal ice zone using passive microwave observations.

  7. The seasonal sea-ice zone in the glacial Southern Ocean as a carbon sink

    PubMed Central

    Abelmann, Andrea; Gersonde, Rainer; Knorr, Gregor; Zhang, Xu; Chapligin, Bernhard; Maier, Edith; Esper, Oliver; Friedrichsen, Hans; Lohmann, Gerrit; Meyer, Hanno; Tiedemann, Ralf

    2015-01-01

    Reduced surface–deep ocean exchange and enhanced nutrient consumption by phytoplankton in the Southern Ocean have been linked to lower glacial atmospheric CO2. However, identification of the biological and physical conditions involved and the related processes remains incomplete. Here we specify Southern Ocean surface–subsurface contrasts using a new tool, the combined oxygen and silicon isotope measurement of diatom and radiolarian opal, in combination with numerical simulations. Our data do not indicate a permanent glacial halocline related to melt water from icebergs. Corroborated by numerical simulations, we find that glacial surface stratification was variable and linked to seasonal sea-ice changes. During glacial spring–summer, the mixed layer was relatively shallow, while deeper mixing occurred during fall–winter, allowing for surface-ocean refueling with nutrients from the deep reservoir, which was potentially richer in nutrients than today. This generated specific carbon and opal export regimes turning the glacial seasonal sea-ice zone into a carbon sink. PMID:26382319

  8. The seasonal sea-ice zone in the glacial Southern Ocean as a carbon sink.

    PubMed

    Abelmann, Andrea; Gersonde, Rainer; Knorr, Gregor; Zhang, Xu; Chapligin, Bernhard; Maier, Edith; Esper, Oliver; Friedrichsen, Hans; Lohmann, Gerrit; Meyer, Hanno; Tiedemann, Ralf

    2015-01-01

    Reduced surface-deep ocean exchange and enhanced nutrient consumption by phytoplankton in the Southern Ocean have been linked to lower glacial atmospheric CO2. However, identification of the biological and physical conditions involved and the related processes remains incomplete. Here we specify Southern Ocean surface-subsurface contrasts using a new tool, the combined oxygen and silicon isotope measurement of diatom and radiolarian opal, in combination with numerical simulations. Our data do not indicate a permanent glacial halocline related to melt water from icebergs. Corroborated by numerical simulations, we find that glacial surface stratification was variable and linked to seasonal sea-ice changes. During glacial spring-summer, the mixed layer was relatively shallow, while deeper mixing occurred during fall-winter, allowing for surface-ocean refueling with nutrients from the deep reservoir, which was potentially richer in nutrients than today. This generated specific carbon and opal export regimes turning the glacial seasonal sea-ice zone into a carbon sink. PMID:26382319

  9. The seasonal sea-ice zone in the glacial Southern Ocean as a carbon sink

    NASA Astrophysics Data System (ADS)

    Abelmann, Andrea; Gersonde, Rainer; Knorr, Gregor; Zhang, Xu; Chapligin, Bernhard; Maier, Edith; Esper, Oliver; Friedrichsen, Hans; Lohmann, Gerrit; Meyer, Hanno; Tiedemann, Ralf

    2015-09-01

    Reduced surface-deep ocean exchange and enhanced nutrient consumption by phytoplankton in the Southern Ocean have been linked to lower glacial atmospheric CO2. However, identification of the biological and physical conditions involved and the related processes remains incomplete. Here we specify Southern Ocean surface-subsurface contrasts using a new tool, the combined oxygen and silicon isotope measurement of diatom and radiolarian opal, in combination with numerical simulations. Our data do not indicate a permanent glacial halocline related to melt water from icebergs. Corroborated by numerical simulations, we find that glacial surface stratification was variable and linked to seasonal sea-ice changes. During glacial spring-summer, the mixed layer was relatively shallow, while deeper mixing occurred during fall-winter, allowing for surface-ocean refueling with nutrients from the deep reservoir, which was potentially richer in nutrients than today. This generated specific carbon and opal export regimes turning the glacial seasonal sea-ice zone into a carbon sink.

  10. A parameter model of gas exchange for the seasonal sea ice zone

    NASA Astrophysics Data System (ADS)

    Loose, B.; McGillis, W. R.; Perovich, D.; Zappa, C. J.; Schlosser, P.

    2013-07-01

    Carbon budgets for the polar oceans require better constraint on air-sea gas exchange in the sea ice zone (SIZ). Here, we utilize recent advances in the theory of turbulence, mixing and air-sea flux in the ice-ocean boundary layer (IOBL) to formulate a simple model for gas exchange when the surface ocean is partially covered by sea ice. The gas transfer velocity (k) is related to shear-driven and convection-driven turbulence in the aqueous mass boundary layer, and to the mean-squared wave slope at the air-sea interface. We use the model to estimate k along the drift track of Ice-Tethered Profilers (ITPs) in the Arctic. Individual estimates of daily-averaged k from ITP drifts ranged between 1.1 and 22 m d-1, and the fraction of open water (f) ranged from 0 to 0.83. Converted to area-weighted effective transfer velocities (keff), the minimum value of keff was 10-5 m d-1 near f = 0 with values exceeding keff = 5 m d-1 at f = 0.4. The largest values of k occurred during the periods when ice cover around the ITP was changing rapidly; either in advance or retreat. The model indicates that effects from shear and convection in the sea ice zone contribute an additional 40% to the magnitude of keff, beyond what would be predicted from an estimate of keff based solely upon a windspeed parameterization. Although the ultimate scaling relationship for gas exchange in the sea ice zone will require validation in laboratory and field studies, the basic parameter model described here demonstrates that it is feasible to formulate estimates of k based upon properties of the IOBL using data sources that presently exist.

  11. A parameter model of gas exchange for the seasonal sea ice zone

    NASA Astrophysics Data System (ADS)

    Loose, B.; McGillis, W. R.; Perovich, D.; Zappa, C. J.; Schlosser, P.

    2014-01-01

    Carbon budgets for the polar oceans require better constraint on air-sea gas exchange in the sea ice zone (SIZ). Here, we utilize advances in the theory of turbulence, mixing and air-sea flux in the ice-ocean boundary layer (IOBL) to formulate a simple model for gas exchange when the surface ocean is partially covered by sea ice. The gas transfer velocity (k) is related to shear-driven and convection-driven turbulence in the aqueous mass boundary layer, and to the mean-squared wave slope at the air-sea interface. We use the model to estimate k along the drift track of ice-tethered profilers (ITPs) in the Arctic. Individual estimates of daily-averaged k from ITP drifts ranged between 1.1 and 22 m d-1, and the fraction of open water (f) ranged from 0 to 0.83. Converted to area-weighted effective transfer velocities (keff), the minimum value of keff was 10-55 m d-1 near f = 0 with values exceeding keff = 5 m d-1 at f = 0.4. The model indicates that effects from shear and convection in the sea ice zone contribute an additional 40% to the magnitude of keff, beyond what would be predicted from an estimate of keff based solely upon a wind speed parameterization. Although the ultimate scaling relationship for gas exchange in the sea ice zone will require validation in laboratory and field studies, the basic parameter model described here demonstrates that it is feasible to formulate estimates of k based upon properties of the IOBL using data sources that presently exist.

  12. Modeling the Seasonal Ice Zone from the Air: use of repeat aerial hydrographic surveys to constrain a regional ice-ocean model in an area of rapidly evolving ice cover

    NASA Astrophysics Data System (ADS)

    Dewey, S.; Morison, J.; Zhang, J.

    2015-12-01

    The Seasonal Ice Zone of the Beaufort Sea is the area of ocean north of Alaska over which sea ice melts and reforms annually. It contains the more narrow, near-edge marginal ice zone (MIZ). Seasonal Ice Zone Reconnaissance Surveys (SIZRS) measure hydrography along two meridional sections using Air eXpendable CTDs (AXCTDs) and Air eXpendable Current Profilers (AXCPs). These surveys take place aboard U.S. Coast Guard Arctic Domain Awareness flights of opportunity during each melt season (June-October) starting in 2012. The Marginal Ice Zone Modeling and Assimilation System (MIZMAS) is a high-resolution regional ice-ocean model with daily, three-dimensional output encompassing the SIZRS survey area. Direct comparison of the SIZRS data with MIZMAS output as well as with several regional climatologies can constrain the ice-ocean model and help to explain recent changes in subsurface heat content and salinity. For example, observed freshening relative to climatology has been used as a reference to which MIZMAS surface salinity values can be relaxed. MIZMAS may in turn shed light on the physical mechanisms driving the observed freshening. In addition, use of MIZMAS surface fluxes to drive a one-dimensional mixed layer model gives results close to observations when the model is initialized with SIZRS profiles. Because SIZRS observations range in time from the onset of melt to the onset of Fall freeze-up, the comparison of the one-dimensional model with MIZMAS illustrates the relative roles of local and regional processes in forming near-surface temperature maxima and salinity minima. The SIZRS observations and one-dimensional model are used to constrain MIZMAS estimations of stored subsurface heat while establishing the physical drivers of these temperature and salinity changes.

  13. Spatial distribution of micro- and meso-zooplankton in the seasonal ice zone of east Antarctica during 1983-1995

    NASA Astrophysics Data System (ADS)

    Ojima, Motoha; Takahashi, Kunio T.; Tanimura, Atsushi; Odate, Tsuneo; Fukuchi, Mitsuo

    2015-09-01

    Historically, most studies about the geographic distribution of zooplankton in the Southern Ocean have been focused on the macro-sized zooplankton (2-20 mm), such as the Antarctic krill and larger-sized copepods. On the other hand, despite the high abundance and biomass, the distribution patterns of micro- (20-200 μm) and meso-sized (200 μm-2 mm) zooplankton communities are little understood. In this study, we investigated the distribution patterns of larger micro-zooplankton (100-200 μm) and meso-zooplankton communities in the seasonal ice zone in the Cosmonaut Sea near Syowa Station and examined the effects of environmental factors and water properties on these communities. The investigation was based on samples collected with 100 μm mesh nets, which are appropriate to estimate the quantitative abundance and community structure of micro- and meso-zooplankton species between 1983 and 1995. Cluster analysis of the samples revealed that the distribution of macro-zooplankton species was influenced by the temperature and salinity of ocean fronts. Among the meso-zooplankton, cyclopoid and small calanoid copepods tended to be ubiquitously distributed. However, among the micro-zooplankton, the distributions of foraminiferans and tintinnids were associated with sea ice extent. The distribution of micro- and meso-zooplankton communities could be used to estimate the impact of environmental changes on the marine ecosystem in the Southern Ocean.

  14. Observing Physical and Biological Drivers of pH and O2 in a Seasonal Ice Zone in the Ross Sea Using Profiling Float Data

    NASA Astrophysics Data System (ADS)

    Briggs, E.; Martz, T. R.; Talley, L. D.; Mazloff, M. R.

    2015-12-01

    Ice cover has strong influence over gas exchange, vertical stability, and biological production which are critical to understanding the Southern Ocean's central role in oceanic biogeochemical cycling and heat and carbon uptake under a changing climate. However the relative influence of physical versus biological processes in this hard-to-study region is poorly understood due to limited observations. Here we present new findings from a profiling float equipped with biogeochemical sensors in the seasonal ice zone of the Ross Sea capturing, for the first time, under-ice pH profile data over a two year timespan from 2014 to the present. The relative influence of physical (e.g. vertical mixing and air-sea gas exchange) and biological (e.g. production and respiration) drivers of pH and O2 within the mixed layer are explored during the phases of ice formation, ice cover, and ice melt over the two seasonal cycles. During the austral fall just prior to and during ice formation, O2 increases as expected due to surface-layer undersaturation and enhanced gas exchange. A small increase in pH is also observed during this phase, but without a biological signal in accompanying profiling float chlorophyll data, which goes against common reasoning from both a biological and physical standpoint. During the phase of ice cover, gas exchange is inhibited and a clear respiration signal is observed in pH and O2 data from which respiration rates are calculated. In the austral spring, ice melt gives rise to substantial ice edge phytoplankton blooms indicated by O2 supersaturation and corresponding increase in pH and large chlorophyll signal. The influence of the duration of ice cover and mixed layer depth on the magnitude of the ice edge blooms is explored between the two seasonal cycles.

  15. Physical and biological control of protistan community composition, distribution and abundance in the seasonal ice zone of the Southern Ocean between 30 and 80°E

    NASA Astrophysics Data System (ADS)

    Davidson, Andrew T.; Scott, Fiona J.; Nash, Geraldine V.; Wright, Simon W.; Raymond, Ben

    2010-05-01

    Protists are critical components of the Antarctic marine ecosystem as they comprise most of the living carbon and are the base of the Antarctic food web. They are also key determinants of vertical carbon flux and mediate draw-down of atmospheric CO 2 by the ocean. The community composition, abundance and distribution of marine protists (phytoplankton and protozoa) was studied during the Baseline Research on Oceanography, Krill and the Environment-West (BROKE-West) survey, in the seasonal ice zone during the 2005-2006 austral summer between 30°E and 80°E. Light and electron microscopy were used to determine the protistan composition and abundance in samples obtained at 30 sites from surface waters and at 26 sites from the depth of the maximum in situ chlorophyll fluorescence (Chl max). Cluster analysis was used to identify 5 groups of sample sites at the surface and 5 at the Chl max that were of similar protist composition and abundance. The physical characteristics, taxonomic composition, indicator taxa, and taxonomic diversity were determined for each group. In the southwest, a bloom of colonial Phaeocystis antarctica dominated the protistan community composition and biomass amongst the receding ice, but this was replaced by the flagellate life stage/s of this haptophyte in waters to the north. In the southeast, a diatom bloom had the highest diversity of protist taxa observed during the survey and centric diatoms dominated the biomass. Outside these blooms, grazing by krill probably reduced the composition and abundance of large diatoms and autotrophic dinoflagellates in coastal to mid-inshore waters. Only in offshore waters did large diatoms and dinoflagellates increase in abundance and diversity, despite low concentrations of iron and silicate at many of these sites. This increase was probably due to reduced top-down control by krill and other large zooplankton. Large diatoms dominated in offshore waters, despite other coincident studies showing that the

  16. Gas diffusion through columnar laboratory sea ice: implications for mixed-layer ventilation of CO2 in the seasonal ice zone

    NASA Astrophysics Data System (ADS)

    Loose, B.; Schlosser, P.; Perovich, D.; Ringelberg, D.; Ho, D. T.; Takahashi, T.; Richter-Menge, J.; Reynolds, C. M.; McGillis, W. R.; Tison, J.-L.

    2011-02-01

    Gas diffusion through the porous microstructure of sea ice represents a pathway for ocean-atmosphere exchange and for transport of biogenic gases produced within sea ice. We report on the experimental determination of the bulk gas diffusion coefficients, D, for oxygen (O2) and sulphur hexafluoride (SF6) through columnar sea ice under constant ice thickness conditions for ice surface temperatures between -4 and -12 °C. Profiles of SF6 through the ice indicate decreasing gas concentration from the ice/water interface to the ice/air interface, with evidence for solubility partitioning between gas-filled and liquid-filled pore spaces. On average, ? was 1.3 × 10-4 cm2 s-1 (±40%) and ? was 3.9 × 10-5 cm2 s-1 (±41%). The preferential partitioning of SF6 to the gas phase, which is the dominant diffusion pathway produced the greater rate of SF6 diffusion. Comparing these estimates of D with an existing estimate of the air-sea gas transfer through leads indicates that ventilation of the mixed layer by diffusion through sea ice may be negligible, compared to air-sea gas exchange through fractures in the ice pack, even when the fraction of open water is less than 1%.

  17. Caterpillar-like ice motion in the ablation zone of the Greenland ice sheet

    NASA Astrophysics Data System (ADS)

    Ryser, C.; Lüthi, M. P.; Andrews, L. C.; Catania, G. A.; Funk, M.; Hawley, R.; Hoffman, M.; Neumann, T. A.

    2014-10-01

    Current understanding of ice dynamics predicts that increasing availability and variability of meltwater will have an impact on basal motion and therefore on the evolution and future behavior of the Greenland ice sheet. We present measurements of ice deformation, subglacial water pressure, and surface velocity that show periodic and episodic variations on several time scales (seasonal, multiday, and diurnal). These variations, observed with GPS and sensors at different depths throughout the ice column, are not synchronous but show delayed responses of ice deformation with increasing depth and basal water pressure in antiphase with surface velocity. With the help of a Full-Stokes ice flow model, these observations are explained as ice motion in a caterpillar-like fashion. Caused by patches of different basal slipperiness, horizontal stress transfer through the stiff central part of the ice body leads to spatially varying surface velocities and ice deformation patterns. Variation of this basal slipperiness induces characteristic patterns of ice deformation variability that explain the observed behavior. Ice flow in the ablation zone of the Greenland ice sheet is therefore controlled by activation of basal patches by varying slipperiness in the course of a melt season, leading to caterpillar-like ice motion superposed on the classical shear deformation.

  18. Solar radiation interactions with seasonal sea ice

    NASA Astrophysics Data System (ADS)

    Ehn, Jens Kristian

    Presently, the Arctic Ocean is undergoing an escalating reduction in sea ice and a transition towards a seasonal sea ice environment. This warrants detailed investigations into improving our understanding of the seasonal evolution of sea ice and snow covers, and their representation in climate models. The interaction of solar radiation with sea ice is an important process influencing the energy balance and biological activity in polar seas, and consequently plays a key role in the earth's climate system. This thesis focuses on characterization of the optical properties---and the underlying physical properties that determine them---of seasonal sea ice during the fall freeze-up and the spring melt periods. Both periods display high spatial heterogeneity and rapid temporal changes in sea ice properties, and are therefore poorly understood. Field data were collected in Amundsen Gulf/Franklin Bay (FB), southern-eastern Beaufort Sea, in Oct.-Nov. 2003 and Apr. 2004 and in Button Bay (BB), western Hudson Bay, in Mar.-May 2005 to address (1) the temporal and spatial evolution of surface albedo and transmittance, (2) how radiative transfer in sea ice is controlled by its physical nature, and (3) the characteristics of the bottom ice algae community and its effect on the optical properties. The fall study showed the importance of surface features such as dry or slushy bare ice, frost flowers and snow cover in determining the surface albedo. Ice thickness was also important, however, mostly because surface features were associated with thickness. For example, nilas (<10 cm thick) was typically not covered by a snow layer as snow grains were dissolved or merged with the salty and warm brine skim layer on the surface, while surface conditions on thicker ice types were cold and dry enough to support a snow cover. In general, the surface albedo increased exponentially with an ice thickness increase, however, variability within ice thickness types were very large. It is apparent

  19. Seasonal Changes of Arctic Sea Ice Physical Properties Observed During N-ICE2015: An Overview

    NASA Astrophysics Data System (ADS)

    Gerland, S.; Spreen, G.; Granskog, M. A.; Divine, D.; Ehn, J. K.; Eltoft, T.; Gallet, J. C.; Haapala, J. J.; Hudson, S. R.; Hughes, N. E.; Itkin, P.; King, J.; Krumpen, T.; Kustov, V. Y.; Liston, G. E.; Mundy, C. J.; Nicolaus, M.; Pavlov, A.; Polashenski, C.; Provost, C.; Richter-Menge, J.; Rösel, A.; Sennechael, N.; Shestov, A.; Taskjelle, T.; Wilkinson, J.; Steen, H.

    2015-12-01

    Arctic sea ice is changing, and for improving the understanding of the cryosphere, data is needed to describe the status and processes controlling current seasonal sea ice growth, change and decay. We present preliminary results from in-situ observations on sea ice in the Arctic Basin north of Svalbard from January to June 2015. Over that time, the Norwegian research vessel «Lance» was moored to in total four ice floes, drifting with the sea ice and allowing an international group of scientists to conduct detailed research. Each drift lasted until the ship reached the marginal ice zone and ice started to break up, before moving further north and starting the next drift. The ship stayed within the area approximately 80°-83° N and 5°-25° E. While the expedition covered measurements in the atmosphere, the snow and sea ice system, and in the ocean, as well as biological studies, in this presentation we focus on physics of snow and sea ice. Different ice types could be investigated: young ice in refrozen leads, first year ice, and old ice. Snow surveys included regular snow pits with standardized measurements of physical properties and sampling. Snow and ice thickness were measured at stake fields, along transects with electromagnetics, and in drillholes. For quantifying ice physical properties and texture, ice cores were obtained regularly and analyzed. Optical properties of snow and ice were measured both with fixed installed radiometers, and from mobile systems, a sledge and an ROV. For six weeks, the surface topography was scanned with a ground LIDAR system. Spatial scales of surveys ranged from spot measurements to regional surveys from helicopter (ice thickness, photography) during two months of the expedition, and by means of an array of autonomous buoys in the region. Other regional information was obtained from SAR satellite imagery and from satellite based radar altimetry. The analysis of the data collected has started, and first results will be

  20. Ocean-ice interaction in the marginal ice zone

    NASA Technical Reports Server (NTRS)

    Liu, Antony K.; Peng, Chich Y.

    1994-01-01

    Ocean ice interaction processes in the Marginal Ice Zone (MIZ) by wind, waves, and mesoscale features, such as upwelling and eddies, are studied using ERS-1 Synthetic Aperture Radar (SAR) images and ocean ice interaction model. A sequence of SAR images of the Chukchi Sea MIZ with three days interval are studied for ice edge advance/retreat. Simultaneous current measurements from the northeast Chukchi Sea as well as the Barrow wind record are used to interpret the MIZ dynamics.

  1. Variability in the Antarctic Marginal Ice Zone and Pack Ice in Observations and NCAR CESM

    NASA Astrophysics Data System (ADS)

    Stroeve, J. C.; Campbell, G. G.; Holland, M. M.; Landrum, L.

    2015-12-01

    Sea ice around Antarctica reached another record high extent in September 2014, recording a maximum extent of more than 20 million km2 for the first time since the modern satellite data record began in October 1978. This follows previous record maxima in 2012 and 2013, resulting in an overall increase in Antarctic September sea ice extent of 1.3% per decade since 1979. Several explanations have been put forward to explain the increasing trends, such as anomalous short-term wind patterns that both grow and spread out the ice, and freshening of the surface ocean layer from increased melting of floating ice from the continent. These positive trends in Antarctic sea ice are at odds with climate model forecasts that suggest the sea ice should be declining in response to increasing greenhouse gases and stratospheric ozone depletion. While the reasons for the increases in total extent remain poorly understood, it is likely that these changes are not just impacting the total ice extent, but also the distribution of pack ice, the marginal ice zone (MIZ) and polynyas, with important ramifications for phytoplankton productivity that in turn impact zooplankton, fish, sea birds and marine mammals. This study evaluates changes in the distribution of the pack ice, polynyas and the marginal ice zone around Antarctica from two sea ice algorithms, the NASA Team and the Bootstrap. These results are further compared with climate model simulations from the CESM large ensemble output. Seasonal analysis of the different ice types using NASA Team and Bootstrap shows that during ice advance, the ice advances as pack ice, with a seasonal peak in September (broader peak for Bootstrap), and as the pack ice begins to retreat, it first converts to a wide area of MIZ, that reaches its peak around November (NASA Team) or December (Bootstrap). CESM also shows a similar seasonal cycle, with a peak in the pack ice in August, and a December/January peak in the MIZ. Seasonal variability and trends are

  2. Mapping and Assessing Variability in the Antarctic Marginal Ice Zone, the Pack Ice and Coastal Polynyas

    NASA Astrophysics Data System (ADS)

    Stroeve, Julienne; Jenouvrier, Stephanie

    2016-04-01

    Sea ice variability within the marginal ice zone (MIZ) and polynyas plays an important role for phytoplankton productivity and krill abundance. Therefore mapping their spatial extent, seasonal and interannual variability is essential for understanding how current and future changes in these biological active regions may impact the Antarctic marine ecosystem. Knowledge of the distribution of different ice types to the total Antarctic sea ice cover may also help to shed light on the factors contributing towards recent expansion of the Antarctic ice cover in some regions and contraction in others. The long-term passive microwave satellite data record provides the longest and most consistent data record for assessing different ice types. However, estimates of the amount of MIZ, consolidated pack ice and polynyas depends strongly on what sea ice algorithm is used. This study uses two popular passive microwave sea ice algorithms, the NASA Team and Bootstrap to evaluate the distribution and variability in the MIZ, the consolidated pack ice and coastal polynyas. Results reveal the NASA Team algorithm has on average twice the MIZ and half the consolidated pack ice area as the Bootstrap algorithm. Polynya area is also larger in the NASA Team algorithm, and the timing of maximum polynya area may differ by as much as 5 months between algorithms. These differences lead to different relationships between sea ice characteristics and biological processes, as illustrated here with the breeding success of an Antarctic seabird.

  3. Energy transport in the marginal ice zone

    NASA Astrophysics Data System (ADS)

    Dixon, Tony W.; Squire, Vernon A.

    2001-09-01

    A novel approach to modeling ocean wave scattering in the marginal ice zone that uses the coherent potential approximation to compute the energy transport velocity is reported. The necessary theory is developed by considering sea ice floes to be thin elastic beams governed by the Euler-Bernoulli equation, with the open water surrounding each floe subject to the same equation with its material coefficients set to be very small quantities. This mathematical stratagem facilitates the solution of the problem and yields interesting results about the speed at which wave energy propagates through a marginal ice zone, the dispersion relation for a random mixture of ice floes and water, and the mean free path or attenuation coefficient. Results from the model are compared with data reported by Wadhams et al. [1988].

  4. Spatially Mapped Reductions in the Length of the Arctic Sea Ice Season

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.

    2014-01-01

    Satellite data are used to determine the number of days having sea ice coverage in each year 1979-2013 and to map the trends in these ice-season lengths. Over the majority of the Arctic seasonal sea ice zone, the ice season shortened at an average rate of at least 5 days/decade between 1979 and 2013, and in a small area in the northeastern Barents Sea the rate of shortening reached over 65 days/decade. The only substantial non-coastal area with lengthening sea ice seasons is the Bering Sea, where the ice season lengthened by 5-15 days/decade. Over the Arctic as a whole, the area with ice seasons shortened by at least 5 days/decade is 12.4 × 10(exp 6) square kilimeters, while the area with ice seasons lengthened by at least 5 days/decade is only 1.1 × 10(exp 6) square kilometers. The contrast is even greater, percentage-wise, for higher rates.

  5. Modeling Wave-Ice Interactions in the Marginal Ice Zone

    NASA Astrophysics Data System (ADS)

    Orzech, Mark; Shi, Fengyan; Bateman, Sam; Veeramony, Jay; Calantoni, Joe

    2015-04-01

    The small-scale (O(m)) interactions between waves and ice floes in the marginal ice zone (MIZ) are investigated with a coupled model system. Waves are simulated with the non-hydrostatic finite-volume model NHWAVE (Ma et al., 2012) and ice floes are represented as bonded collections of smaller particles with the discrete element system LIGGGHTS (Kloss et al., 2012). The physics of fluid and ice are recreated as authentically as possible, to allow the coupled system to supplement and/or substitute for more costly and demanding field experiments. The presentation will first describe the development and validation of the coupled system, then discuss the results of a series of virtual experiments in which ice floe and wave characteristics are varied to examine their effects on energy dissipation, MIZ floe size distribution, and ice pack retreat rates. Although Wadhams et al. (1986) suggest that only a small portion (roughly 10%) of wave energy entering the MIZ is reflected, dissipation mechanisms for the remaining energy have yet to be delineated or measured. The virtual experiments are designed to focus on specific properties and processes - such as floe size and shape, collision and fracturing events, and variations in wave climate - and measure their relative roles the transfer of energy and momentum from waves to ice. Questions to be examined include: How is energy dissipated by ice floe collisions, fracturing, and drag, and how significant is the wave attenuation associated with each process? Do specific wave/floe length scale ratios cause greater wave attenuation? How does ice material strength affect the rate of wave energy loss? The coupled system will ultimately be used to test and improve upon wave-ice parameterizations for large-scale climate models. References: >Kloss, C., C. Goniva, A. Hager, S. Amberger, and S. Pirker (2012). Models, algorithms and validation for opensource DEM and CFD-DEM. Progress in Computational Fluid Dynamics 12(2/3), 140-152. >Ma, G

  6. A coupled ice-ocean model of ice breakup and banding in the marginal ice zone

    NASA Technical Reports Server (NTRS)

    Smedstad, O. M.; Roed, L. P.

    1985-01-01

    A coupled ice-ocean numerical model for the marginal ice zone is considered. The model consists of a nonlinear sea ice model and a two-layer (reduced gravity) ocean model. The dependence of the upwelling response on wind stress direction is discussed. The results confirm earlier analytical work. It is shown that there exist directions for which there is no upwelling, while other directions give maximum upwelling in terms of the volume of uplifted water. The ice and ocean is coupled directly through the stress at the ice-ocean interface. An interesting consequence of the coupling is found in cases when the ice edge is almost stationary. In these cases the ice tends to break up a few tenths of kilometers inside of the ice edge.

  7. Change and Variability in East Antarctic Sea Ice Seasonality, 1979/80–2009/10

    PubMed Central

    Massom, Robert; Reid, Philip; Stammerjohn, Sharon; Raymond, Ben; Fraser, Alexander; Ushio, Shuki

    2013-01-01

    Recent analyses have shown that significant changes have occurred in patterns of sea ice seasonality in West Antarctica since 1979, with wide-ranging climatic, biological and biogeochemical consequences. Here, we provide the first detailed report on long-term change and variability in annual timings of sea ice advance, retreat and resultant ice season duration in East Antarctica. These were calculated from satellite-derived ice concentration data for the period 1979/80 to 2009/10. The pattern of change in sea ice seasonality off East Antarctica comprises mixed signals on regional to local scales, with pockets of strongly positive and negative trends occurring in near juxtaposition in certain regions e.g., Prydz Bay. This pattern strongly reflects change and variability in different elements of the marine “icescape”, including fast ice, polynyas and the marginal ice zone. A trend towards shorter sea-ice duration (of 1 to 3 days per annum) occurs in fairly isolated pockets in the outer pack from∼95–110°E, and in various near-coastal areas that include an area of particularly strong and persistent change near Australia's Davis Station and between the Amery and West Ice Shelves. These areas are largely associated with coastal polynyas that are important as sites of enhanced sea ice production/melt. Areas of positive trend in ice season duration are more extensive, and include an extensive zone from 160–170°E (i.e., the western Ross Sea sector) and the near-coastal zone between 40–100°E. The East Antarctic pattern is considerably more complex than the well-documented trends in West Antarctica e.g., in the Antarctic Peninsula-Bellingshausen Sea and western Ross Sea sectors. PMID:23705008

  8. Change and variability in East antarctic sea ice seasonality, 1979/80-2009/10.

    PubMed

    Massom, Robert; Reid, Philip; Stammerjohn, Sharon; Raymond, Ben; Fraser, Alexander; Ushio, Shuki

    2013-01-01

    Recent analyses have shown that significant changes have occurred in patterns of sea ice seasonality in West Antarctica since 1979, with wide-ranging climatic, biological and biogeochemical consequences. Here, we provide the first detailed report on long-term change and variability in annual timings of sea ice advance, retreat and resultant ice season duration in East Antarctica. These were calculated from satellite-derived ice concentration data for the period 1979/80 to 2009/10. The pattern of change in sea ice seasonality off East Antarctica comprises mixed signals on regional to local scales, with pockets of strongly positive and negative trends occurring in near juxtaposition in certain regions e.g., Prydz Bay. This pattern strongly reflects change and variability in different elements of the marine "icescape", including fast ice, polynyas and the marginal ice zone. A trend towards shorter sea-ice duration (of 1 to 3 days per annum) occurs in fairly isolated pockets in the outer pack from∼95-110°E, and in various near-coastal areas that include an area of particularly strong and persistent change near Australia's Davis Station and between the Amery and West Ice Shelves. These areas are largely associated with coastal polynyas that are important as sites of enhanced sea ice production/melt. Areas of positive trend in ice season duration are more extensive, and include an extensive zone from 160-170°E (i.e., the western Ross Sea sector) and the near-coastal zone between 40-100°E. The East Antarctic pattern is considerably more complex than the well-documented trends in West Antarctica e.g., in the Antarctic Peninsula-Bellingshausen Sea and western Ross Sea sectors.

  9. The Influence of the Zonal Wave Three on Antarctic Sea Ice during Ice Advance Season

    NASA Astrophysics Data System (ADS)

    Khan, H. M.; Raphael, M. N.

    2015-12-01

    Previous works have looked at the influence of key atmospheric circulation patterns on sea ice in the Antarctic in terms of the atmosphere's seasonal cycle. This study examines the influence of one of these atmospheric patterns, the zonal wave three (ZW3), in terms of the sea ice's seasons from 1979-2009 in order to better understand the response of the sea ice. An index to represent the amplitude of the ZW3 was calculated using zonal anomalies of 850 hPa geopotential heights taken from the ERA-Interim data set. Sea ice concentrations (SIC), taken from the Hadley Center sea ice and sea surface temperature data set, were found to be significantly positively correlated with the ZW3 index during the ice advance season (March to August) in the Ross and Weddell Seas and off the Amery ice shelf. These regions align with where cold, southerly flow associated with the ZW3 are found. In the Amundsen-Bellingshausen Seas region, SIC was found to be negatively correlated with the ZW3 index, which coincides with where the warm, northerly flow of the wave is found in this region. Regression analysis showed SIC to be significantly dependent upon the ZW3 in parts of the Ross Sea, the ice edge in the Amundsen-Bellingshausen Seas and off the Amery ice shelf during ice advance season. The results suggest that the ZW3 plays a role in the occurrence of the observed sea ice trends in the Ross Sea, Amundsen-Bellingshausen Seas, Weddell Sea and off the Amery ice shelf regions during the ice advance season, the critical period for sea ice growth. The results also demonstrate that re-examining the influence of relevant atmospheric patterns on sea ice in terms of the ice's seasonal cycles could allow firmer connections to be established between sea ice trends and atmospheric patterns.

  10. Determining the ice seasons severity during 1982-2015 using the ice extents sum as a new characteristic

    NASA Astrophysics Data System (ADS)

    Rjazin, Jevgeni; Pärn, Ove

    2016-04-01

    Sea ice is a key climate factor and it restricts considerably the winter navigation in sever seasons on the Baltic Sea. So determining ice conditions severity and describing ice cover behaviour at severe seasons interests scientists, engineers and navigation managers. The present study is carried out to determine the ice seasons severity degree basing on the ice seasons 1982 to 2015. A new integrative characteristic is introduced to describe the ice season severity. It is the sum of ice extents of the ice season id est the daily ice extents of the season are summed. The commonly used procedure to determine the ice season severity degree by the maximal ice extent is in this research compared to the new characteristic values. The remote sensing data on the ice concentrations on the Baltic Sea published in the European Copernicus Programme are used to obtain the severity characteristic values. The ice extents are calculated on these ice concentration data. Both the maximal ice extent of the season and a newly introduced characteristic - the ice extents sum are used to classify the winters with respect of severity. The most severe winter of the reviewed period is 1986/87. Also the ice seasons 1981/82, 1984/85, 1985/86, 1995/96 and 2002/03 are classified as severe. Only three seasons of this list are severe by both the criteria. They are 1984/85, 1985/86 and 1986/87. We interpret this coincidence as the evidence of enough-during extensive ice cover in these three seasons. In several winters, for example 2010/11 ice cover extended enough for some time, but did not endure. At few other ice seasons as 2002/03 the Baltic Sea was ice-covered in moderate extent, but the ice cover stayed long time. At 11 winters the ice extents sum differed considerably (> 10%) from the maximal ice extent. These winters yield one third of the studied ice seasons. The maximal ice extent of the season is simple to use and enables to reconstruct the ice cover history and to predict maximal ice

  11. Zonal variations in abundance and body length of chaetognaths in the 140°E seasonal ice zone during the austral summer of 2001/02

    NASA Astrophysics Data System (ADS)

    Terazaki, Makoto; Takahashi, Kunio T.; Odate, Tsuneo

    2013-03-01

    Time-series observations of chaetognaths were carried out during four cruises along the 140°E transect between 61°S and 66°28‧S from November to March in the 2001/02 austral summer. Three species -Eukrohnia hamata, Sagitta gazellae and Sagitta marri - occurred in the samples between 0 and 150 m. E. hamata was the most dominant species comprising between 89.6 and 100% of the chaetognath population, followed by S. gazellae (0-5.7%). There were large differences in the abundance and size frequency distribution of body length of E. hamata between the north and south of the Southern Boundary of the Antarctic Circumpolar Current (SB-ACC) which was located between 64°S and 65°S. For E. hamata, low abundance and large sized animals (22-24 mm) occurred south of the SB-ACC. A possible reason could be that the breeding season in waters north of the SB-ACC may be early spring and summer. On the other hand, low reproduction was recognized by low the abundance of E. hamata and few occurrences of juveniles south of the SB-ACC (65°S). The result of a general comparison suggests that the abundance of chaetognaths along the 140°E transect has decreased during the 20 years since 1983.

  12. SIPEX--Exploring the Antarctic Sea Ice Zone

    ERIC Educational Resources Information Center

    Zicus, Sandra; Dobson, Jane; Worby, Anthony

    2008-01-01

    Sea ice in the polar regions plays a key role in both regulating global climate and maintaining marine ecosystems. The international Sea Ice Physics and Ecosystem eXperiment (SIPEX) explored the sea ice zone around Antarctica in September and October 2007, investigating relationships between the physical sea ice environment and the structure of…

  13. Waves and mesoscale features in the marginal ice zone

    NASA Technical Reports Server (NTRS)

    Liu, Antony K.; Peng, Chih Y.

    1993-01-01

    Ocean-ice interaction processes in the Marginal Ice Zone (MIZ) by waves and mesoscale features, such as upwelling and eddies, are studied using ERS-1 Synthetic Aperture Radar (SAR) imagery and wave-ice interaction models. Satellite observations of mesoscale features can play a crucial role in ocean-ice interaction study.

  14. Impact of sea ice initialisation on sea ice and atmosphere prediction skill on seasonal timescales

    NASA Astrophysics Data System (ADS)

    Guemas, Virginie; Chevallier, Matthieu; Deque, Michel; Bellprat, Omar; Doblas-Reyes, Francisco; Fuckar, Neven-Stjepan

    2016-04-01

    We present a robust assessment of the impact of sea ice initialisation from observations on the sea ice and atmosphere prediction skill. We ran two ensemble seasonal prediction experiments from 1979 to 2012: one using the highest possible quality for sea ice initial conditions and another where sea ice is initialized from a climatology, with two forecast systems. During the freezing season in the Arctic Ocean, sea ice forecasts become skilful with sea ice initialization until three to five months ahead, thanks to the memory held by sea ice thickness. During the melting season in both the Arctic and Antarctic Oceans, sea ice forecasts are skilful for seven and two months respectively with negligible differences between the two experiments, the memory being held by the ocean heat content. A weak impact on the atmosphere prediction skill is obtained.

  15. Impact of sea ice initialization on sea ice and atmosphere prediction skill on seasonal timescales

    NASA Astrophysics Data System (ADS)

    Guemas, V.; Chevallier, M.; Déqué, M.; Bellprat, O.; Doblas-Reyes, F.

    2016-04-01

    We present a robust assessment of the impact of sea ice initialization from reconstructions of the real state on the sea ice and atmosphere prediction skill. We ran two ensemble seasonal prediction experiments from 1979 to 2012 : one using realistic sea ice initial conditions and another where sea ice is initialized from a climatology, with two forecast systems. During the melting season in the Arctic Ocean, sea ice forecasts become skilful with sea ice initialization until 3-5 months ahead, thanks to the memory held by sea ice thickness. During the freezing season in both the Arctic and Antarctic Oceans, sea ice forecasts are skilful for 7 and 2 months, respectively, with negligible differences between the two experiments, the memory being held by the ocean heat content. A weak impact on the atmosphere prediction skill is obtained.

  16. CO2, CH4, and N2O in the Open Ocean, Sea-ice Zone, and Polynya of the Southern Ocean Observed during Austral Summer Season from 2009 to 2013

    NASA Astrophysics Data System (ADS)

    Rhee, T. S.; Park, K.; Hahm, D.; Jeon, H.; Park, K.; Kwon, Y.; Shin, H.; Lee, S.; Lee, K. E.

    2013-12-01

    Korean ice-breaking research vessel Araon has been at sea since 2010 carrying out a variety of research activities. During these periods we measured CO2, CH4, and N2O at sea below and above the sea surface to estimate sink or source strengths of the ocean in the characteristic provinces at high latitude. The ocean plays a wide range of role in the budget of these gases in the atmosphere: as a sink for CO2 and a source for CH4 and N2O. High latitude of the Southern Ocean is particularly important as the change in the cryosphere can impact the ecological and physical settings that govern the content and flux of these dissolved gases in seawater. We have visited the Amundsen Sea during the austral summer in 2010/2011 and 2012, and the Ross Sea in 2013 in order to investigate the impact of the change in the cryospheric environments. In addition we had opportunity to survey the Pacific sector of the Southern Ocean in 2009 onboard R/V Polarstern. In the open ocean, CO2 in the seawater was mostly undersaturated, CH4 was in equilibrium or slightly undersaturated, and N2O was supersaturated with respect to that in the marine boundary layer. These features were not observed in the sea-ice zone; CO2 in the seawater was slightly supersaturated in 2011, but not in 2012 and 2013, while dissolved CH4 was undersaturated and N2O was supersaturated for three years. In the polynya of the Amundsen Sea and the Ross Sea, CO2 and CH4 were undersaturated in the seawater while N2O was supersaturated with respect to that in the atmosphere. Based on these 4-year observations during austral summer season, high latitude of the southern ocean contributes as a strong sink for atmospheric CO2 whilst as a strong source for N2O. In the case of CH4, the Southern Ocean acted as a sink of the atmospheric CH4, which differs from the role of the ocean in the global scale.

  17. Remote sensing of the Fram Strait marginal ice zone

    USGS Publications Warehouse

    Shuchman, R.A.; Burns, B.A.; Johannessen, O.M.; Josberger, E.G.; Campbell, W.J.; Manley, T.O.; Lannelongue, N.

    1987-01-01

    Sequential remote sensing images of the Fram Strait marginal ice zone played a key role in elucidating the complex interactions of the atmosphere, ocean, and sea ice. Analysis of a subset of these images covering a 1-week period provided quantitative data on the mesoscale ice morphology, including ice edge positions, ice concentrations, floe size distribution, and ice kinematics. The analysis showed that, under light to moderate wind conditions, the morphology of the marginal ice zone reflects the underlying ocean circulation. High-resolution radar observations showed the location and size of ocean eddies near the ice edge. Ice kinematics from sequential radar images revealed an ocean eddy beneath the interior pack ice that was verified by in situ oceanographic measurements.

  18. Factors affecting dynamical seasonal prediction of the Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Wang, W.; Chen, M.; Kumar, A.; Hung, M.

    2013-12-01

    Arctic sea ice variability has received increasing attention during the last decade. Seasonal prediction of the Arctic sea ice has been primarily produced with statistical methods during the past years. A few operational centers have recently implemented dynamical sea ice component in the coupled atmosphere-ocean forecast systems for seasonal climate prediction. Yet various issues remain to be resolved for an improved prediction of seasonal sea ice variations. In this study, we analyze the forecast of sea ice extent in the NCEP Climate Forecast System version 2 (CFSv2) and address factors that affect the representation of the observed sea ice variability in the forecast model. The analysis will be based on retrospective and real-time 9-month forecasts from the CFSv2 for 1982-2012. We will first assess the overall performance of the CFSv2 in capturing the observed sea ice extent climatology, long-term trend, and interannual anomalies. We will then discuss factors that affect the sea ice prediction, including: (1) consistency of the initialization of the observed sea ice concentration, (2) impacts of surface heat fluxes related to atmospheric model physics, (3) bias in sea surface temperatures, and (4) impacts of initial sea ice thickness.

  19. Environment at the Grounding Zone of the Whillans Ice Stream-Ross Ice Shelf, West Antarctica

    NASA Astrophysics Data System (ADS)

    Hodson, T. O.; Powell, R. D.; Mikucki, J.; Scherer, R. P.; Tulaczyk, S. M.; Coenen, J. J.; Puttkammer, R.; Branecky, C.

    2015-12-01

    Grounding zones where grounded ice sheets transition to floating ice shelves, are the primary gateways through which the Antarctic Ice Sheet loses mass to the ocean. In these environments, ice, ocean, meltwater and sediment meet and interact, influencing both the ice sheet and ocean circulation beneath the ice shelf. Here, we report on conditions near the grounding zone of the Whillans Ice Stream, which feeds into the Ross Ice Shelf. Cameras and instruments lowered through an access borehole to the ocean cavity beneath the ice shelf found a 10m-thick water column comprising an upper layer of colder ice shelf water formed from mixing between meltwater with the lower layer of warmer higher salinity shelf water. This style of stratification is typical of large ice shelves, but it was uncertain whether it existed so near the grounding zone, where stronger tidal currents and/or strong subglacial stream discharges could mix the water column. Salinity and temperature of the water suggest it formed from sea ice production in the Western Ross Sea, with minimal modification beneath the ice shelf. This source region is distinct from waters previously observed at the nearby J-9 borehole, illustrating the importance of the sub-ice shelf bathymetry in steering circulation between the ocean and the grounding zone. Preliminary data suggest an active exchange of heat and nutrients between the grounding zone and the open ocean, despite being separated by 600km. Thus life found near the grounding line is probably not an isolated oasis, but may instead be part of a much broader ecosystem that spans the ice shelf. Although sea ice formation presently maintains water in the sub-ice shelf cavity near the surface freezing point, buffering many larger ice shelves from gradual ocean warming, these findings suggest that even grounding zones of extensive ice shelves may respond quickly to abrupt changes in ocean circulation, such as that observed in the Amundsen Sea.

  20. Skill improvement of dynamical seasonal Arctic sea ice forecasts

    NASA Astrophysics Data System (ADS)

    Krikken, Folmer; Schmeits, Maurice; Vlot, Willem; Guemas, Virginie; Hazeleger, Wilco

    2016-05-01

    We explore the error and improve the skill of the outcome from dynamical seasonal Arctic sea ice reforecasts using different bias correction and ensemble calibration methods. These reforecasts consist of a five-member ensemble from 1979 to 2012 using the general circulation model EC-Earth. The raw model reforecasts show large biases in Arctic sea ice area, mainly due to a differently simulated seasonal cycle and long term trend compared to observations. This translates very quickly (1-3 months) into large biases. We find that (heteroscedastic) extended logistic regressions are viable ensemble calibration methods, as the forecast skill is improved compared to standard bias correction methods. Analysis of regional skill of Arctic sea ice shows that the Northeast Passage and the Kara and Barents Sea are most predictable. These results show the importance of reducing model error and the potential for ensemble calibration in improving skill of seasonal forecasts of Arctic sea ice.

  1. Antarctic Sea ice variations and seasonal air temperature relationships

    NASA Technical Reports Server (NTRS)

    Weatherly, John W.; Walsh, John E.; Zwally, H. J.

    1991-01-01

    Data through 1987 are used to determine the regional and seasonal dependencies of recent trends of Antarctic temperature and sea ice. Lead-lag relationships involving regional sea ice and air temperature are systematically evaluated, with an eye toward the ice-temperature feedbacks that may influence climatic change. Over the 1958-1087 period the temperature trends are positive in all seasons. For the 15 years (l973-l987) for which ice data are available, the trends are predominantly positive only in winter and summer, and are most strongly positive over the Antarctic Peninsula. The spatially aggregated trend of temperature for this latter period is small but positive, while the corresponding trend of ice coverage is small but negative. Lag correlations between seasonal anomalies of the two variables are generally stronger with ice lagging the summer temperatures and with ice leading the winter temperatures. The implication is that summer temperatures predispose the near-surface waters to above-or below-normal ice coverage in the following fall and winter.

  2. Ice sheet (de)stabilization via grounding zone processes (Invited)

    NASA Astrophysics Data System (ADS)

    Christianson, K. A.; Horgan, H.; Parizek, B. R.; Alley, R. B.; Anandakrishnan, S.; Jacobel, R. W.; Keisling, B. A.; Dalla Santa, K. L.; Craig, B.; Walker, R. T.

    2013-12-01

    Much of the threshold behavior of marine ice sheets is thought to result from processes occurring at the grounding zone, where the ice sheet transitions into the ice shelf. At short time-scales (decades to centuries), grounding zone behavior is likely to be influenced by ongoing sediment deposition, which can stabilize the grounding zone position. Tidally driven flexure just inland of an ice shelf can further enhance stabilization by compacting subglacial till and thereby locally increasing basal shear stress. However, this competes with ocean-driven melt across a several-kilometers-wide grounding zone, where warm ocean water infiltration around bedrock obstacles can result in rapid grounding line retreat. Here we present a suite of geophysical observations (ice-penetrating radar, active-source seismic, GPS, and laser altimetry data) and data-assimilated modeling for one relatively stable (Whillans Ice Stream) and one potentially unstable (Thwaites Glacier) grounding zone in West Antarctica. The geophysical data show that estuaries occur beneath ice sheet grounding zones, where interactions between ocean water, subglacial hydrology, sediment, and tidal processes are complex and occur across a several-kilometers-wide grounding zone. Our modeling results indicate that ice stream stabilization on bedrock highs narrower than the length of the tidally-influenced grounding zone may be ephemeral if circulating warm ocean waters reduce basal resistance and enhance melt across the grounding zone. Stabilization is, however, significantly enhanced by effectively plastic beds and zones of high basal shear stress, which can be created via till compaction from tidal flexure. Thus accurate future projections of sea level require correct understanding of till rheology and local grounding zone processes (interaction of sediment, ocean water, subglacial water, and tidal processes), which are not presently included in modern whole-ice-sheet models.

  3. Seasonal Evolution of Snow Cover on Antarctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Maksym, T.; Leonard, K. C.; Trujillo, E.; White, S.; Wilkinson, J.; Stammerjohn, S. E.; Mei, J.

    2015-12-01

    Snow cover on Antarctic sea ice plays a key role in the evolution of ice thickness, its estimation from space-borne altimeters, and structuring of sea ice ecosystems. Yet until recently, there have been very few continuous observations of the seasonal evolution of snow cover on Antarctic sea ice. We present observations of the seasonal evolution of the snow cover from ice mass balance buoys (IMBs) deployed between 2009 and 2013 in the Weddell, Bellingshausen, and Amundsen Seas and the East Antarctic sector. In addition, automatic weather stations that provided direct observations of precipitation, accumulation, and blowing snow were deployed alongside IMBs in October, 2012 in the East Antarctic during the Sea Ice Physics and Ecosystem eXperiment II (SIPEX II), and in July and August, 2013 in the Weddell Sea during the Antarctic Winter Ecosystem and Climate Study (AWECS). These buoys show markedly different snow accumulation regimes in each sector, although accumulation is also strongly controlled by the local morphology of the ice cover through snow erosion and deposition during blowing snow and precipitations events. Comparisons of snow accumulation from these buoys with estimates from atmospheric reanalysis and the direct measurements of precipitation and blowing snow show that precipitation is generally not a good estimator of snow accumulation. Improved treatment of blowing snow is needed if sea ice models are to accurately simulate Antarctic snow and sea ice mass balance. In summer, melting of the snow pack is relatively modest in most cases. Nevertheless, it appears to play an important role in governing sea ice hydrology and sea ice surface properties, and hence may play an important role in modulating sea ice primary productivity.

  4. Wave effects on ocean-ice interaction in the marginal ice zone

    NASA Technical Reports Server (NTRS)

    Liu, Antony K.; Hakkinen, Sirpa; Peng, Chih Y.

    1993-01-01

    The effects of wave train on ice-ocean interaction in the marginal ice zone are studied through numerical modeling. A coupled two-dimensional ice-ocean model has been developed to include wave effects and wind stress for the predictions of ice edge dynamics. The sea ice model is coupled to the reduced-gravity ocean model through interfacial stresses. The main dynamic balance in the ice momentum is between water-ice stress, wind stress, and wave radiation stresses. By considering the exchange of momentum between waves and ice pack through radiation stress for decaying waves, a parametric study of the effects of wave stress and wind stress on ice edge dynamics has been performed. The numerical results show significant effects from wave action. The ice edge is sharper, and ice edge meanders form in the marginal ice zone owing to forcing by wave action and refraction of swell system after a couple of days. Upwelling at the ice edge and eddy formation can be enhanced by the nonlinear effects of wave action; wave action sharpens the ice edge and can produce ice meandering, which enhances local Ekman pumping and pycnocline anomalies. The resulting ice concentration, pycnocline changes, and flow velocity field are shown to be consistent with previous observations.

  5. Mechanism of seasonal Arctic sea ice evolution and Arctic amplification

    NASA Astrophysics Data System (ADS)

    Kim, Kwang-Yul; Hamlington, Benjamin D.; Na, Hanna; Kim, Jinju

    2016-09-01

    Sea ice loss is proposed as a primary reason for the Arctic amplification, although the physical mechanism of the Arctic amplification and its connection with sea ice melting is still in debate. In the present study, monthly ERA-Interim reanalysis data are analyzed via cyclostationary empirical orthogonal function analysis to understand the seasonal mechanism of sea ice loss in the Arctic Ocean and the Arctic amplification. While sea ice loss is widespread over much of the perimeter of the Arctic Ocean in summer, sea ice remains thin in winter only in the Barents-Kara seas. Excessive turbulent heat flux through the sea surface exposed to air due to sea ice reduction warms the atmospheric column. Warmer air increases the downward longwave radiation and subsequently surface air temperature, which facilitates sea surface remains to be free of ice. This positive feedback mechanism is not clearly observed in the Laptev, East Siberian, Chukchi, and Beaufort seas, since sea ice refreezes in late fall (November) before excessive turbulent heat flux is available for warming the atmospheric column in winter. A detailed seasonal heat budget is presented in order to understand specific differences between the Barents-Kara seas and Laptev, East Siberian, Chukchi, and Beaufort seas.

  6. Seasonal precipitation timing and ice core records

    SciTech Connect

    Steig, E.J.; Grootes, P.M.; Stuiver, M. )

    1994-12-16

    This is a commentary on global circulation model experiments of moisture source changes in Greenland, urging caution in how they are applied because they have important implications for paleoclimate reconstruction from ice cores. The work comes from preliminary find is of a ice core (GISP2) of the authors. The authors conclude that at present anomalies in Greenland ice core records should not be interpreted solely in terms of source region variations. The combined use of oxygen 18, D and ionic species in the new Summit, Greenland cores should make it possible to answer empirically some of the questions raised by the GCM experiments as to the interpretation of oxygen 18 records in terms of temperature. 4 refs., 1 fig.

  7. The 2013 Arctic Field Season of the NRL Sea-Ice Measurement Program

    NASA Astrophysics Data System (ADS)

    Gardner, J. M.; Brozena, J. M.; Ball, D.; Hagen, R. A.; Liang, R.; Stoudt, C.

    2013-12-01

    The U.S. Naval Research Laboratory (NRL) is conducting a five year study of the changing Arctic with a particular focus on ice thickness and distribution variability with the intent of optimizing state-of-the-art computer models which are currently used to predict sea ice changes. An important part of our study is to calibrate/validate CryoSat2 ice thickness data prior to its incorporation into new ice forecast models. NRL Code 7420 collected coincident data with the CryoSat2 satellite in 2011 and 2012 using a LiDAR (Riegl Q560) to measure combined snow and ice thickness and a 10 GHz pulse-limited precision radar altimeter to measure sea-ice freeboard. This field season, LiDAR data was collected using the Riegl Q680 which permitted higher density operation and data collection. Concident radar data was collected using an improved version of the NRL 10 GHz pulse limited radar that was used for the 2012 fieldwork. 8 coincident tracks of CryoSat2 satellite data were collected. Additionally a series of grids (7 total) of adjacent tracks were flown coincident with Cryosat2 satellite overpass. These grids cover the approximate satellite footprint of the satellite on the ice as it passes overhead. Data from these grids are shown here and will be used to examine the relationship of the tracked satellite waveform data to the actual surface across the footprint. We also coordinated with the Seasonal Ice Zone Observing Network (SIZONet) group who conducted surface based ice thickness surveys using a Geonics EM-31 along hunter trails on the landfast ice near Barrow as well as on drifting ice offshore during helicopter landings. On two sorties, a twin otter carrying the NRL LiDAR and radar altimeter flew in tandem with the helicopter carrying the EM-31 to achieve synchronous data acquisition. Data from these flights are shown here along with a digital elevation map.

  8. Seasonal Greenland Ice Sheet ice flow variations in regions of differing bed and surface topography

    NASA Astrophysics Data System (ADS)

    Sole, A. J.; Livingstone, S. J.; Rippin, D. M.; Hill, J.; McMillan, M.; Quincey, D. J.

    2015-12-01

    The contribution of the Greenland Ice Sheet (GrIS) to future sea-level rise is uncertain. Observations reveal the important role of basal water in controlling ice-flow to the ice sheet margin. In Greenland, drainage of large volumes of surface meltwater to the ice sheet bed through moulins and hydrofracture beneath surface lakes dominates the subglacial hydrological system and provides an efficient means of moving mass and heat through the ice sheet. Ice surface and bed topography influence where meltwater can access the bed, and the nature of its subsequent flow beneath the ice. However, no systematic investigation into the influence of topographic variability on Greenland hydrology and dynamics exists. Thus, physical processes controlling storage and drainage of surface and basal meltwater, and the way these affect ice flow are not comprehensively understood. This presents a critical obstacle in efforts to predict the future evolution of the GrIS. Here we present high-resolution satellite mapping of the ice-surface drainage network (e.g. lakes, channels and moulins) and measurements of seasonal variations in ice flow in south west Greenland. The region is comprised of three distinct subglacial terrains which vary in terms of the amplitude and wavelength and thus the degree to which basal topography is reflected in the ice sheet surface. We find that the distribution of surface hydrological features is related to the transfer of bed topography to the ice sheet surface. For example, in areas of thinner ice and high bed relief, moulins occur more frequently and are more uniformly dispersed, indicating a more distributed influx of surface-derived meltwater to the ice sheet bed. We investigate the implications of such spatial variations in surface hydrology on seasonal ice flow rates.

  9. Mapping and assessing variability in the Antarctic marginal ice zone, pack ice and coastal polynyas in two sea ice algorithms with implications on breeding success of snow petrels

    NASA Astrophysics Data System (ADS)

    Stroeve, Julienne C.; Jenouvrier, Stephanie; Campbell, G. Garrett; Barbraud, Christophe; Delord, Karine

    2016-08-01

    Sea ice variability within the marginal ice zone (MIZ) and polynyas plays an important role for phytoplankton productivity and krill abundance. Therefore, mapping their spatial extent as well as seasonal and interannual variability is essential for understanding how current and future changes in these biologically active regions may impact the Antarctic marine ecosystem. Knowledge of the distribution of MIZ, consolidated pack ice and coastal polynyas in the total Antarctic sea ice cover may also help to shed light on the factors contributing towards recent expansion of the Antarctic ice cover in some regions and contraction in others. The long-term passive microwave satellite data record provides the longest and most consistent record for assessing the proportion of the sea ice cover that is covered by each of these ice categories. However, estimates of the amount of MIZ, consolidated pack ice and polynyas depend strongly on which sea ice algorithm is used. This study uses two popular passive microwave sea ice algorithms, the NASA Team and Bootstrap, and applies the same thresholds to the sea ice concentrations to evaluate the distribution and variability in the MIZ, the consolidated pack ice and coastal polynyas. Results reveal that the seasonal cycle in the MIZ and pack ice is generally similar between both algorithms, yet the NASA Team algorithm has on average twice the MIZ and half the consolidated pack ice area as the Bootstrap algorithm. Trends also differ, with the Bootstrap algorithm suggesting statistically significant trends towards increased pack ice area and no statistically significant trends in the MIZ. The NASA Team algorithm on the other hand indicates statistically significant positive trends in the MIZ during spring. Potential coastal polynya area and amount of broken ice within the consolidated ice pack are also larger in the NASA Team algorithm. The timing of maximum polynya area may differ by as much as 5 months between algorithms. These

  10. SIPEX—exploring the Antarctic sea ice zone

    NASA Astrophysics Data System (ADS)

    Zicus, Sandra; Dobson, Jane; Worby, Anthony

    2008-11-01

    Sea ice in the polar regions plays a key role in both regulating global climate and maintaining marine ecosystems. The international Sea Ice Physics and Ecosystem eXperiment (SIPEX) explored the sea ice zone around Antarctica in September and October 2007, investigating relationships between the physical sea ice environment and the structure of Southern Ocean ecosystems. One of the main goals of SIPEX was to conduct large-scale sea ice and snow thickness surveys for the validation of satellite-based measurements. SIPEX scientists used a variety of techniques including helicopter-based radar and laser altimetry, as well as a remotely operated underwater vehicle, to gather baseline data on Antarctic sea ice thickness and the under-ice environment. These data will be invaluable for monitoring possible future changes in the sea ice around Antarctica.

  11. Norwegian remote sensing experiment in a marginal ice zone

    USGS Publications Warehouse

    Farrelly, B.; Johannessen, J.A.; Svendsen, E.; Kloster, K.; Horjen, I.; Matzler, C.; Crawford, J.; Harrington, R.; Jones, L.; Swift, C.; Delnore, V.E.; Cavalieri, D.; Gloersen, P.; Hsiao, S.V.; Shemdin, O.H.; Thompson, T.W.; Ramseier, R.O.; Johannessen, O.M.; Campbell, W.J.

    1983-01-01

    The Norwegian Remote Sensing Experiment in the marginal ice zone north of Svalbard took place in fall 1979. Coordinated passive and active microwave measurements were obtained from shipborne, airborne, and satellite instruments together with in situ observations. The obtained spectra of emissivity (frequency range, 5 to 100 gigahertz) should improve identification of ice types and estimates of ice concentration. Mesoscale features along the ice edge were revealed by a 1.215-gigahertz synthetic aperture radar. Ice edge location by the Nimbus 7 scanning multichannel microwave radiometer was shown to be accurate to within 10 kilometers.

  12. Microwave properties of sea ice in the marginal ice zone

    NASA Technical Reports Server (NTRS)

    Onstott, R. G.; Larson, R. W.

    1986-01-01

    Active microwave properties of summer sea ice were measured. Backscatter data were acquired at frequencies from 1 to 17 GHz, at angles from 0 to 70 deg from vertical, and with like and cross antenna polarizations. Results show that melt-water, snow thickness, snowpack morphology, snow surface roughness, ice surface roughness, and deformation characteristics are the fundamental scene parameters which govern the summer sea ice backscatter response. A thick, wet snow cover dominates the backscatter response and masks any ice sheet features below. However, snow and melt-water are not distributed uniformly and the stage of melt may also be quite variable. These nonuniformities related to ice type are not necessarily well understood and produce unique microwave signature characteristics.

  13. 76 FR 1362 - Safety Zone; Ice Conditions for the Baltimore Captain of Port Zone

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-10

    ... Federal Register (73 FR 3316). Public Meeting We do not now plan to hold a public meeting. But you may... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Ice Conditions for the Baltimore Captain of.... This safety zone is necessary to protect mariners from the hazards associated with ice in the...

  14. Regional seasonal forecasts of the Arctic sea ice in two coupled climate models

    NASA Astrophysics Data System (ADS)

    Chevallier, Matthieu; Guémas, Virginie; Salas y Mélia, David; Doblas-Reyes, Francisco

    2015-04-01

    The predictive capabilities of two state-of-the-art coupled atmosphere-ocean global climate models (CNRM-CM5.1 and EC-Earth v2.3) in seasonal forecasting of the Arctic sea ice will be presented with a focus on regional skill. 5-month hindcasts of September sea ice area in the Arctic peripherial seas (Barents-Kara seas, Laptev-East Siberian seas, Chukchi sea and Beaufort sea) and March sea ice area in the marginal ice zones (Barents, Greenland, Labrador, Bering and Okhotsk sea) have been produced over the period 1990-2009. Systems mainly differ with respect to the initialization strategy, the ensemble generation techniques and the sea ice components. Predictive skill, assessed in terms of actual and potential predictability, is comparable in the two systems for both summer and winter hindcasts. Most interestingly, the multi-model prediction is often better than individual predictions in several sub-basins, including the Barents sea in the winter and most shelf seas in the summer. Systematic biases are also reduced using the multi-model predictions. Results from this study show that a regional zoom of global seasonal forecasts could be useful for operational needs. This study also show that the multi-model approach may be the step forward in producing accurate and reliable seasonal forecasts based on coupled global climate models.

  15. 46 CFR 42.30-5 - Northern Winter Seasonal Zones and area.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... Excluded from this zone are the North Atlantic Winter Seasonal Zone I and the Baltic Sea bounded by the... FOREIGN VOYAGES BY SEA Zones, Areas, and Seasonal Periods § 42.30-5 Northern Winter Seasonal Zones...

  16. 46 CFR 42.30-5 - Northern Winter Seasonal Zones and area.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... Excluded from this zone are the North Atlantic Winter Seasonal Zone I and the Baltic Sea bounded by the... FOREIGN VOYAGES BY SEA Zones, Areas, and Seasonal Periods § 42.30-5 Northern Winter Seasonal Zones...

  17. 46 CFR 42.30-5 - Northern Winter Seasonal Zones and area.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... Excluded from this zone are the North Atlantic Winter Seasonal Zone I and the Baltic Sea bounded by the... FOREIGN VOYAGES BY SEA Zones, Areas, and Seasonal Periods § 42.30-5 Northern Winter Seasonal Zones...

  18. A coupled ice-ocean model of upwelling in the marginal ice zone

    NASA Technical Reports Server (NTRS)

    Roed, L. P.; Obrien, J. J.

    1983-01-01

    A dynamical coupled ice-ocean numerical model for the marginal ice zone (MIZ) is suggested and used to study upwelling dynamics in the MIZ. The nonlinear sea ice model has a variable ice concentration and includes internal ice stress. The model is forced by stresses on the air/ocean and air/ice surfaces. The main coupling between the ice and the ocean is in the form of an interfacial stress on the ice/ocean interface. The ocean model is a linear reduced gravity model. The wind stress exerted by the atmosphere on the ocean is proportional to the fraction of open water, while the interfacial stress ice/ocean is proportional to the concentration of ice. A new mechanism for ice edge upwelling is suggested based on a geostrophic equilibrium solution for the sea ice medium. The upwelling reported in previous models invoking a stationary ice cover is shown to be replaced by a weak downwelling due to the ice motion. Most of the upwelling dynamics can be understood by analysis of the divergence of the across ice edge upper ocean transport. On the basis of numerical model, an analytical model is suggested that reproduces most of the upwelling dynamics of the more complex numerical model.

  19. Bimodal albedo distributions in the ablation zone of the southwestern Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Moustafa, S. E.; Rennermalm, A. K.; Smith, L. C.; Miller, M. A.; Mioduszewski, J. R.

    2014-09-01

    Surface albedo is a key variable controlling solar radiation absorbed at the Greenland Ice Sheet (GrIS) surface, and thus, meltwater production. Recent decline in surface albedo over the GrIS has been linked to enhanced snow grain metamorphic rates and amplified ice-albedo feedback from atmospheric warming. However, the importance of distinct surface types on ablation zone albedo and meltwater production is still relatively unknown, and excluded in surface mass balance models. In this study, we analyze albedo and ablation rates using in situ and remotely-sensed data. Observations include: (1) a new high-quality in situ spectral albedo dataset collected with an Analytical Spectral Devices (ASD) spectroradiometer measuring at 325-1075 nm, along a 1.25 km transect during three days in June 2013; (2) broadband albedo at two automatic weather stations; and (3) daily MODerate Resolution Imaging Spectroradiometer (MODIS) albedo (MOD10A1) between 31 May and 30 August. We find that seasonal ablation zone albedos have a bimodal distribution, with two alternate states. This suggests that an abrupt switch from high to low albedo can be triggered by a modest melt event, resulting in amplified surface ablation rates. Our results show that such a shift corresponds to an observed melt rate percent difference increase of 51.6% during peak melt season (between 10-14 and 20-24 July 2013). Furthermore, our findings demonstrate that seasonal changes in GrIS ablation zone albedo are not exclusively a function of a darkening surface from ice crystal growth, but rather are controlled by changes in the fractional coverage of snow, bare ice, and impurity-rich surface types. As the climate continues to warm, regional climate models should consider the seasonal evolution of ice surface types in Greenland's ablation zone to improve projections of mass loss contributions to sea level rise.

  20. Bimodal Albedo Distributions in the Ablation Zone of the Southwestern Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Moustafa, S.; Rennermalm, A. K.; Smith, L. C.; Miller, M. A.; Mioduszewski, J.; Koenig, L.

    2014-12-01

    Surface albedo is a key variable controlling solar radiation absorbed at the Greenland Ice Sheet (GrIS) surface, and thus meltwater production. Recent decline in surface albedo over the GrIS has been linked to enhanced snow grain metamorphic rates and amplified ice-albedo feedback from atmospheric warming. However, the importance of distinct surface types on ablation zone albedo and meltwater production is still relatively unknown, and excluded in surface mass balance models. In this study, we analyze albedo and ablation rates (m d-1) using in situ and remotely-sensed data. Observations include: 1) a new high-quality in situ spectral albedo dataset collected with an Analytical Spectral Devices (ASD) spectroradiometer measuring at 325-1075 nm, along a 1.25 km transect during three days in June 2013; 2) broadband albedo at two automatic weather stations; and 3) daily MODerate Resolution Imaging Spectroradiometer (MODIS) albedo (MOD10A1) between 31 May and 30 August. We find that seasonal ablation zone albedos have a bimodal distribution, with two alternate states. This suggests that an abrupt switch from high to low albedo can be triggered by a modest melt event, resulting in amplified ablation rates. Our results show that such a shift corresponds to an observed melt rate percent difference increase of 51.6% during peak melt season (between 10-14 July and 20-24 July, 2013). Furthermore, our findings demonstrate that seasonal changes in GrIS ablation zone albedo are not exclusively a function of a darkening surface from ice crystal growth, but rather are controlled by changes in the fractional coverage of snow, bare ice, and impurity-rich surface types. As the climate continues to warm, regional climate models should consider the seasonal evolution of ice surface types in Greenland's ablation zone to improve projections of mass loss contributions to sea level rise.

  1. Identification of paleo Arctic winter sea ice limits and the marginal ice zone: Optimised biomarker-based reconstructions of late Quaternary Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Belt, Simon T.; Cabedo-Sanz, Patricia; Smik, Lukas; Navarro-Rodriguez, Alba; Berben, Sarah M. P.; Knies, Jochen; Husum, Katrine

    2015-12-01

    Analysis of >100 surface sediments from across the Barents Sea has shown that the relative abundances of the mono-unsaturated sea ice diatom-derived biomarker IP25 and a tri-unsaturated highly branched isoprenoid (HBI) lipid (HBI III) are characteristic of the overlying surface oceanographic conditions, most notably, the location of the seasonal sea ice edge. Thus, while IP25 is generally limited to locations experiencing seasonal sea ice, with higher abundances found for locations with longer periods of ice cover, HBI III is found in sediments from all sampling locations, but is significantly enhanced in sediments within the vicinity of the retreating sea ice edge or marginal ice zone (MIZ). The response of HBI III to this well-defined sea ice scenario also appears to be more selective than that of the more generic phytoplankton biomarker, brassicasterol. The potential for the combined analysis of IP25 and HBI III to provide more detailed assessments of past sea ice conditions than IP25 alone has been investigated by quantifying both biomarkers in three marine downcore records from locations with contrasting modern sea ice settings. For sediment cores from the western Barents Sea (intermittent seasonal sea ice) and the northern Norwegian Sea (ice-free), high IP25 and low HBI III during the Younger Dryas (ca. 12.9-11.9 cal. kyr BP) is consistent with extensive sea cover, with relatively short periods of ice-free conditions resulting from late summer retreat. Towards the end of the YD (ca. 11.9-11.5 cal. kyr BP), a general amelioration of conditions resulted in a near winter maximum ice edge scenario for both locations, although this was somewhat variable, and the eventual transition to predominantly ice-free conditions was later for the western Barents Sea site (ca. 9.9 cal. kyr BP) compared to NW Norway (ca. 11.5 cal. kyr BP). For both locations, coeval elevated HBI III (but absent IP25) potentially provides further evidence for increased Atlantic Water inflow

  2. Seismic exploration noise reduction in the Marginal Ice Zone.

    PubMed

    Tollefsen, Dag; Sagen, Hanne

    2014-07-01

    A sonobuoy field was deployed in the Marginal Ice Zone of the Fram Strait in June 2011 to study the spatial variability of ambient noise. High noise levels observed at 10-200 Hz are attributed to distant (1400 km range) seismic exploration. The noise levels decreased with range into the ice cover; the reduction is fitted by a spreading loss model with a frequency-dependent attenuation factor less than for under-ice interior Arctic propagation. Numerical modeling predicts transmission loss of the same order as the observed noise level reduction and indicates a significant loss contribution from under-ice interaction. PMID:24993237

  3. Microwave and physical properties of sea ice in the winter marginal ice zone

    NASA Technical Reports Server (NTRS)

    Tucker, W. B., III; Perovich, D. K.; Gow, A. J.; Grenfell, T. C.; Onstott, R. G.

    1991-01-01

    Surface-based active and passive microwave measurements were made in conjunction with ice property measurements for several distinct ice types in the Fram Strait during March and April 1987. Synthesis aperture radar imagery downlinked from an aircraft was used to select study sites. The surface-based radar scattering cross section and emissivity spectra generally support previously inferred qualitative relationships between ice types, exhibiting expected separation between young, first-year and multiyear ice. Gradient ratios, calculated for both active and passive data, appear to allow clear separation of ice types when used jointly. Surface flooding of multiyear floes, resulting from excessive loading and perhaps wave action, causes both active and passive signatures to resemble those of first-year ice. This effect could possibly cause estimates of ice type percentages in the marginal ice zone to be in error when derived from aircraft- or satellite-born sensors.

  4. Understanding the Sea Ice Zone: Scientists and Communities Partnering to Archive, Analyze and Disseminate Local Ice Observations

    NASA Astrophysics Data System (ADS)

    Collins, J. A.; Oldenburg, J.; Liu, M.; Pulsifer, P. L.; Kaufman, M.; Eicken, H.; Parsons, M. A.

    2012-12-01

    Knowledge of sea ice is critical to the hunting, whaling, and cultural activities of many Indigenous communities in Northern and Western Alaska. Experienced hunters have monitored seasonal changes of the sea ice over many years, giving them a unique expertise in assessing the current state of the sea ice as well as any anomalies in seasonal sea ice conditions. The Seasonal Ice Zone Observing Network (SIZONet), in collaboration with the Exchange for Local Observations and Knowledge of the Arctic (ELOKA), has developed an online application for collecting, storing, and analyzing sea ice observations contributed by local experts from coastal Alaskan communities. Here we present the current iteration of the application, outline future plans and discuss how the development process and resulting system have improved our collective understanding of sea ice processes and changes. The SIZONet application design is based on the needs of the research scientists responsible for entering observation data into the database, the needs of local sea ice experts contributing their observations and knowledge, and the information needs of Alaska coastal communities. Entry forms provide a variety of input methods, including menus, check boxes, and free text input. Input options strive to balance flexibility in capturing concepts and details with the need for analytical consistency. Currently, research staff at the University of Alaska Fairbanks use the application to enter observations received via written or electronic communications from local sea ice experts. Observation data include current weather conditions, snow and ice quantity and quality, and wildlife sighted or taken. Future plans call for direct use of the SIZONet interface by local sea ice experts as well as students, both as contributors to the data collection and as users seeking meaning in the data. This functionality is currently available to a limited number of community members as we extend the application to support

  5. Arctic sea ice a major determinant in Mandt's black guillemot movement and distribution during non-breeding season.

    PubMed

    Divoky, G J; Douglas, D C; Stenhouse, I J

    2016-09-01

    Mandt's black guillemot (Cepphus grylle mandtii) is one of the few seabirds associated in all seasons with Arctic sea ice, a habitat that is changing rapidly. Recent decreases in summer ice have reduced breeding success and colony size of this species in Arctic Alaska. Little is known about the species' movements and distribution during the nine month non-breeding period (September-May), when changes in sea ice extent and composition are also occurring and predicted to continue. To examine bird movements and the seasonal role of sea ice to non-breeding Mandt's black guillemots, we deployed and recovered (n = 45) geolocators on individuals at a breeding colony in Arctic Alaska during 2011-2015. Black guillemots moved north to the marginal ice zone (MIZ) in the Beaufort and Chukchi seas immediately after breeding, moved south to the Bering Sea during freeze-up in December, and wintered in the Bering Sea January-April. Most birds occupied the MIZ in regions averaging 30-60% sea ice concentration, with little seasonal variation. Birds regularly roosted on ice in all seasons averaging 5 h d(-1), primarily at night. By using the MIZ, with its roosting opportunities and associated prey, black guillemots can remain in the Arctic during winter when littoral waters are completely covered by ice.

  6. Arctic sea ice a major determinant in Mandt's black guillemot movement and distribution during non-breeding season.

    PubMed

    Divoky, G J; Douglas, D C; Stenhouse, I J

    2016-09-01

    Mandt's black guillemot (Cepphus grylle mandtii) is one of the few seabirds associated in all seasons with Arctic sea ice, a habitat that is changing rapidly. Recent decreases in summer ice have reduced breeding success and colony size of this species in Arctic Alaska. Little is known about the species' movements and distribution during the nine month non-breeding period (September-May), when changes in sea ice extent and composition are also occurring and predicted to continue. To examine bird movements and the seasonal role of sea ice to non-breeding Mandt's black guillemots, we deployed and recovered (n = 45) geolocators on individuals at a breeding colony in Arctic Alaska during 2011-2015. Black guillemots moved north to the marginal ice zone (MIZ) in the Beaufort and Chukchi seas immediately after breeding, moved south to the Bering Sea during freeze-up in December, and wintered in the Bering Sea January-April. Most birds occupied the MIZ in regions averaging 30-60% sea ice concentration, with little seasonal variation. Birds regularly roosted on ice in all seasons averaging 5 h d(-1), primarily at night. By using the MIZ, with its roosting opportunities and associated prey, black guillemots can remain in the Arctic during winter when littoral waters are completely covered by ice. PMID:27601723

  7. Seasonal evolution of the albedo of multiyear Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Perovich, D. K.; Grenfell, T. C.; Light, B.; Hobbs, P. V.

    2002-10-01

    As part of ice albedo feedback studies during the Surface Heat Budget of the Arctic Ocean (SHEBA) field experiment, we measured spectral and wavelength-integrated albedo on multiyear sea ice. Measurements were made every 2.5 m along a 200-m survey line from April through October. Initially, this line was completely snow covered, but as the melt season progressed, it became a mixture of bare ice and melt ponds. Observed changes in albedo were a combination of a gradual evolution due to seasonal transitions and abrupt shifts resulting from synoptic weather events. There were five distinct phases in the evolution of albedo: dry snow, melting snow, pond formation, pond evolution, and fall freeze-up. In April the surface albedo was high (0.8-0.9) and spatially uniform. By the end of July the average albedo along the line was 0.4, and there was significant spatial variability, with values ranging from 0.1 for deep, dark ponds to 0.65 for bare, white ice. There was good agreement between surface-based albedos and measurements made from the University of Washington's Convair-580 research aircraft. A comparison between net solar irradiance computed using observed albedos and a simplified model of seasonal evolution shows good agreement as long as the timing of the transitions is accurately determined.

  8. Autonomous Investigations of Marginal Ice Zone Processes- Changing Feedbacks and Observational Challenges

    NASA Astrophysics Data System (ADS)

    Lee, Craig; Doble, Martin; Maslowski, Wieslaw; Stanton, Tim; Timmermans, Mary-Louise; Thomson, Jim; Wilkinson, Jeremy

    2015-04-01

    The observed reduction of Arctic summertime sea ice extent and expansion of the marginal ice zone (MIZ) have profound impacts on the balance of processes controlling sea ice evolution, including the introduction of several positive feedback mechanisms that may act to accelerate melting. Examples of such feedbacks include increased upper ocean warming though absorption of solar radiation, elevated internal wave energy and mixing that may entrain heat stored in subsurface watermasses (e.g. the relatively warm Pacific Summer (PSW) and Atlantic (AW) waters) and elevated surface wave energy that acts to deform and fracture sea ice, all of which grow in importance with increasing open water extent. Investigations of MIZ dynamics must resolve the short spatial and temporal scales associated with the processes that govern the exchange of momentum, heat and freshwater near the atmosphere-ice-ocean interface while also achieving the spatial scope and temporal persistence required to characterize how the balance of processes shifts as a function of evolving open water fraction and open water fetch to the south. The recent Office of Naval Research (ONR) Marginal Ice Zone program employed an integrated system of autonomous platforms to provide high-resolution measurements that extend from open water, through the MIZ and deep into ice-covered regions while providing persistence to quantify evolution over an entire summertime melt season. This presentation will provide an overview of the strategy developed by the ONR MIZ team and present early results from the 2014 field program.

  9. Sea ice melting in the marginal ice zone.

    USGS Publications Warehouse

    Josberger, E.G.

    1983-01-01

    The heat and salt flux boundary conditions together with the freezing curve relationship are a necessary component of any ice- sea water thermodynamic model. A neutral two-layer oceanic planetary boundary layer model that incorporates these boundary conditions is used. The results are discussed. -from Author

  10. Effects of Wind and Sea Ice Drift on the Seasonal Variation of Warm Circumpolar Deep Water in the Amundsen Sea

    NASA Astrophysics Data System (ADS)

    Kim, T. W.; Wahlin, A.; Ha, H. K.; Lee, S.; Lee, J. H.

    2014-12-01

    We examined the effect of wind and sea ice on seasonal variation in the thickness of circumpolar deep water, to better understand the processes causing mass loss in the West Antarctic ice sheet (WAIS). Spatial and temporal variation of the layer of warm and salty circumpolar deep water (CDW) at the center of the Amundsen Shelf was measured during two oceanographic surveys and a two-year mooring deployment. A hydrographic transect from the deep ocean, across the shelf break, and into the Dotson Trough shows a local elevation of the warm deep water layer at the shelf break. On the shelf, the water flows south-east along the trough. The thickness of the warm layer displays seasonal variation with maximum thickness in austral summer and minimum thickness in austral winter. The variation in warm layer thickness gives rise to a seasonal variation of the modified CDW heat content. In order to investigate the effects of wind and sea ice drift on the heat content, ocean surface stress was calculated using the ERA interim reanalysis wind data and observed sea ice velocity and concentration from satellites. The Ekman pumping velocity was calculated from the ocean surface stress field. The Ekman pumping at the shelf break, where the warm layer is elevated, shows a strong seasonal variation coinciding with the mooring data. The average wind field is eastward north of the shelf break and westward south of the shelf break during all seasons. The main effect of a layer of sea ice (between the wind and the water) is to reduce the surface stress which can intensify the horizontal gradient of surface stress at the marginal ice zone. This creates a divergence of the Ekman transport and a positive Ekman pumping at the marginal ice zone, if the wind direction is eastward. From February to April, a marginal ice zone close to the shelf break gives rise to a positive Ekman pumping that may explain the seasonal signal seen in the mooring data. At northern boundaries of coastal polynya

  11. Sensitivity studies with a coupled ice-ocean model of the marginal ice zone

    NASA Technical Reports Server (NTRS)

    Roed, L. P.

    1983-01-01

    An analytical coupled ice-ocean model is considered which is forced by a specified wind stress acting on the open ocean as well as the ice. The analysis supports the conjecture that the upwelling dynamics at ice edges can be understood by means of a simple analytical model. In similarity with coastal problems it is shown that the ice edge upwelling is determined by the net mass flux at the boundaries of the considered region. The model is used to study the sensitivity of the upwelling dynamics in the marginal ice zone to variation in the controlling parameters. These parameters consist of combinations of the drag coefficients used in the parameterization of the stresses on the three interfaces atmosphere-ice, atmosphere-ocean, and ice-ocean. The response is shown to be sensitive to variations in these parameters in that one set of parameters may give upwelling while a slightly different set of parameters may give downwelling.

  12. Marginal Ice Zone Processes Observed from Unmanned Aerial Systems

    NASA Astrophysics Data System (ADS)

    Zappa, C. J.

    2015-12-01

    Recent years have seen extreme changes in the Arctic. Marginal ice zones (MIZ), or areas where the "ice-albedo feedback" driven by solar warming is highest and ice melt is extensive, may provide insights into the extent of these changes. Furthermore, MIZ play a central role in setting the air-sea CO2 balance making them a critical component of the global carbon cycle. Incomplete understanding of how the sea-ice modulates gas fluxes renders it difficult to estimate the carbon budget in MIZ. Here, we investigate the turbulent mechanisms driving mixing and gas exchange in leads, polynyas and in the presence of ice floes using both field and laboratory measurements. Measurements from unmanned aerial systems (UAS) in the marginal ice zone were made during 2 experiments: 1) North of Oliktok Point AK in the Beaufort Sea were made during the Marginal Ice Zone Ocean and Ice Observations and Processes EXperiment (MIZOPEX) in July-August 2013 and 2) Fram Strait and Greenland Sea northwest of Ny-Ålesund, Svalbard, Norway during the Air-Sea-Ice Physics and Biogeochemistry Experiment (ASIPBEX) April - May 2015. We developed a number of new payloads that include: i) hyperspectral imaging spectrometers to measure VNIR (400-1000 nm) and NIR (900-1700 nm) spectral radiance; ii) net longwave and net shortwave radiation for ice-ocean albedo studies; iii) air-sea-ice turbulent fluxes as well as wave height, ice freeboard, and surface roughness with a LIDAR; and iv) drone-deployed micro-drifters (DDµD) deployed from the UAS that telemeter temperature, pressure, and RH as it descends through the atmosphere and temperature and salinity of the upper meter of the ocean once it lands on the ocean's surface. Visible and IR imagery of melting ice floes clearly defines the scale of the ice floes. The IR imagery show distinct cooling of the skin sea surface temperature (SST) as well as an intricate circulation and mixing pattern that depends on the surface current, wind speed, and near

  13. Arctic sea ice trends, variability and implications for seasonal ice forecasting.

    PubMed

    Serreze, Mark C; Stroeve, Julienne

    2015-07-13

    September Arctic sea ice extent over the period of satellite observations has a strong downward trend, accompanied by pronounced interannual variability with a detrended 1 year lag autocorrelation of essentially zero. We argue that through a combination of thinning and associated processes related to a warming climate (a stronger albedo feedback, a longer melt season, the lack of especially cold winters) the downward trend itself is steepening. The lack of autocorrelation manifests both the inherent large variability in summer atmospheric circulation patterns and that oceanic heat loss in winter acts as a negative (stabilizing) feedback, albeit insufficient to counter the steepening trend. These findings have implications for seasonal ice forecasting. In particular, while advances in observing sea ice thickness and assimilating thickness into coupled forecast systems have improved forecast skill, there remains an inherent limit to predictability owing to the largely chaotic nature of atmospheric variability.

  14. Arctic sea ice trends, variability and implications for seasonal ice forecasting

    PubMed Central

    Serreze, Mark C.; Stroeve, Julienne

    2015-01-01

    September Arctic sea ice extent over the period of satellite observations has a strong downward trend, accompanied by pronounced interannual variability with a detrended 1 year lag autocorrelation of essentially zero. We argue that through a combination of thinning and associated processes related to a warming climate (a stronger albedo feedback, a longer melt season, the lack of especially cold winters) the downward trend itself is steepening. The lack of autocorrelation manifests both the inherent large variability in summer atmospheric circulation patterns and that oceanic heat loss in winter acts as a negative (stabilizing) feedback, albeit insufficient to counter the steepening trend. These findings have implications for seasonal ice forecasting. In particular, while advances in observing sea ice thickness and assimilating thickness into coupled forecast systems have improved forecast skill, there remains an inherent limit to predictability owing to the largely chaotic nature of atmospheric variability. PMID:26032315

  15. Coupled ice-ocean dynamics in the marginal ice zones Upwelling/downwelling and eddy generation

    NASA Technical Reports Server (NTRS)

    Hakkinen, S.

    1986-01-01

    This study is aimed at modeling mesoscale processes such as upwelling/downwelling and ice edge eddies in the marginal ice zones. A two-dimensional coupled ice-ocean model is used for the study. The ice model is coupled to the reduced gravity ocean model through interfacial stresses. The parameters of the ocean model were chosen so that the dynamics would be nonlinear. The model was tested by studying the dynamics of upwelling. Wings parallel to the ice edge with the ice on the right produce upwelling because the air-ice momentum flux is much greater than air-ocean momentum flux; thus the Ekman transport is greater than the ice than in the open water. The stability of the upwelling and downwelling jets is discussed. The downwelling jet is found to be far more unstable than the upwelling jet because the upwelling jet is stabilized by the divergence. The constant wind field exerted on a varying ice cover will generate vorticity leading to enhanced upwelling/downwelling regions, i.e., wind-forced vortices. Steepening and strengthening of vortices are provided by the nonlinear terms. When forcing is time-varying, the advection terms will also redistribute the vorticity. The wind reversals will separate the vortices from the ice edge, so that the upwelling enhancements are pushed to the open ocean and the downwelling enhancements are pushed underneath the ice.

  16. Melt ponds and marginal ice zone from new algorithm of sea ice concentration retrieval

    NASA Astrophysics Data System (ADS)

    Repina, Irina; Tikhonov, Vasiliy; Komarova, Nataliia; Raev, Mikhail; Sharkov, Evgeniy

    2016-04-01

    Studies of spatial and temporal properties of sea ice distribution in polar regions help to monitor global environmental changes and reveal their natural and anthropogenic factors, as well as make forecasts of weather, marine transportation and fishing conditions, assess perspectives of mineral mining on the continental shelf, etc. Contact methods of observation are often insufficient to meet the goals, very complicated technically and organizationally and not always safe for people involved. Remote sensing techniques are believed to be the best alternative. Its include monitoring of polar regions by means of passive microwave sensing with the aim to determine spatial distribution, types, thickness and snow cover of ice. However, the algorithms employed today to retrieve sea ice characteristics from passive microwave sensing data for different reasons give significant errors, especially in summer period and also near ice edges and in cases of open ice. A new algorithm of sea ice concentration retrieval in polar regions from satellite microwave radiometry data is discussed. Beside estimating sea ice concentration, the algorithm makes it possible to indicate ice areas with melting snow and melt ponds. Melt ponds are an important element of the Arctic climate system. Covering up to 50% of the surface of drifting ice in summer, they are characterized by low albedo values and absorb several times more incident shortwave radiation than the rest of the snow and ice cover. The change of melt ponds area in summer period 1987-2015 is investigated. The marginal ice zone (MIZ) is defined as the area where open ocean processes, including specifically ocean waves, alter significantly the dynamical properties of the sea ice cover. Ocean wave fields comprise short waves generated locally and swell propagating from the large ocean basins. Depending on factors like wind direction and ocean currents, it may consist of anything from isolated, small and large ice floes drifting over a

  17. Trends in the Length of the Southern Ocean Sea Ice Season: 1979-1999

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    Satellite data can be used to observe the sea ice distribution around the continent of Antarctica on a daily basis and hence to determine how many days a year have sea ice at each location. This has been done for each of the 21 years 1979-1999. Mapping the trends in these data over the 21-year period reveals a detailed pattern of changes in the length of the sea ice season around Antarctica. Most of the Ross Sea ice cover has undergone a lengthening of the sea ice season, whereas most of the Amundsen Sea ice cover and almost the entire Bellingshausen Sea ice cover have undergone a shortening of the sea ice season. Results around the rest of the continent, including in the Weddell Sea, are more mixed, but overall, more of the Southern Ocean experienced a lengthening of the sea ice season than a shortening. For instance, the area experiencing a lengthening of the sea ice season by at least 1 day per year is 5.8 x 10(exp 6) sq km, whereas the area experiencing a shortening of the sea ice season by at least 1 day per year is less than half that, at 2.8 x 10(exp 6) sq km. This contrasts sharply with what is happened over the same period in the Arctic, where, overall, there has been some depletion of the ice cover, including shortened sea ice seasons and decreased ice extents.

  18. Anomalous snow accumulation over the southeast region of the Greenland ice sheet during 2002-2003 snow season

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Steffen, K.; Huff, R.; Neumann, G.

    2005-01-01

    Our objective is to determine seasonal snow accumulation in the percolation zone of the Greenland ice sheet on the daily-weekly basis over the large scale. Our approach utilizes data from the Greenland Climate Network (GC-Net) and from the SeaWinds Scatterometer on the QuikSCAT satellite (QSCAT) to measure snow accumulation (SA) in the percolation zone of the Greenland ice sheet. GC-Net measurements provide crucial in-situ data to facilitate the interpretation of QSCAT backscatter signature for the development of an algorithm to map SA.

  19. Seasonal CO2 Ice at Mid-Latitudes on Mars: Implications for Subsurface Water Ice

    NASA Astrophysics Data System (ADS)

    Vincendon, M.; Mustard, J. F.; Forget, F.; Kreslavsky, M. A.; Spiga, A.; Murchie, S. L.; Bibring, J.

    2009-12-01

    The seasonal CO2 ice cap of Mars extends down to about 45° of latitude in the southern hemisphere. At more equatorward latitudes, patches of CO2 ice on pole facing slopes have been reported. We have studied the spatial and temporal distribution of these deposits using the near-IR orbital experiments OMEGA and CRISM. CO2 ice is observed down to 34° of latitude in the austral winter. We have compared these observations with the predictions of a one dimensional energy balance code derived from the LMD GCM. On mid-latitudes pole facing slopes, the model requires an additional source of heat to fit the observations. Changing the parameters of the model related to the ice deposits or to the incoming radiations within the range of known properties cannot account for this mismatch. The most plausible source of heat is a high thermal inertia layer buried below a dry regolith cover, with a latitude dependent depth. This is consistent with the presence of subsurface water ice at mid latitudes on pole facing slopes. The equatorward limit of shallow (< 1 m) subsurface ice as constrained from these observations is 25°S. This value is significantly lower than the current limit determined from low-resolution observations (up to 40° locally), which corresponded to shallow subsurface ice below flat surfaces. Some of the candidates landing sites of the Mars Science Laboratory rover, such as Holden crater, are compatible with our new limit.

  20. Formation processes of floe size distribution in the marginal ice zone (Invited)

    NASA Astrophysics Data System (ADS)

    Toyota, T.; Kohout, A.; Fraser, A.

    2013-12-01

    Since the marginal ice zone (MIZ) is the outer sea ice zone, its behavior is key to the understanding of the variability of sea ice extent associated with climate change. Especially for the melting processes in MIZ, where relatively small ice floes are dominant, floe size distribution (FSD) is an important parameter because smaller ice floes are subject to stronger lateral melting due to their larger cumulative perimeters. As the MIZ is characterized by vigorous interaction between sea ice and waves, breakup of sea ice due to flexural forcing and collisions is considered to play an essential role in the determination of FSD there. However, the available data have been very limited so far. Analysis of the observations of ice floes with a heli-borne video camera, focusing on the floe size ranging from 2 m to 100 m, in the Sea of Okhotsk, the Weddell Sea and off East Antarctica, revealed that while FSD is basically scale-invariant, a regime shift occurs at a size of about a few tens of meters, irrespective of the study region. It was also shown 1) that the floe size at which regime shift occurs slightly increases from 20 to 40 m with ice thickness, consistent with the theory of the flexural failure of sea ice; and 2) that to explain the scale invariance in FSD for smaller floes, a fragility of sea ice which is relevant to the strength of sea ice relative to waves can be a useful physical parameter to be correlated with the fractal dimension. Thus these results confirm the importance of wave-ice interaction to the formation of FSD. Based on this, a possible mechanism of the melting process was hypothesized that in the melting season sea ice extent retreats keeping the FSD relative to the ice edge nearly constant. As a next step and to confirm and further investigate this result, we planned to conduct the concurrent measurements of FSD, wave activities, and ice thickness off East Antarctica during the Sea Ice Physics and Ecosystem Experiment 2 (SIPEX2) in September to

  1. Formation processes of sea ice floe size distribution in the interior pack and its relationship to the marginal ice zone off East Antarctica

    NASA Astrophysics Data System (ADS)

    Toyota, Takenobu; Kohout, Alison; Fraser, Alexander D.

    2016-09-01

    To understand the behavior of the Seasonal Ice Zone (SIZ), which is composed of sea-ice floes of various sizes, knowledge of the floe size distribution (FSD) is important. In particular, FSD in the Marginal Ice Zone (MIZ), controlled by wave-ice interaction, plays an important role in determining the retreating rates of sea-ice extent on a global scale because the cumulative perimeter of floes enhances melting. To improve the understanding of wave-ice interaction and subsequent effects on FSD in the MIZ, FSD measurements were conducted off East Antarctica during the second Sea Ice Physics and Ecosystems eXperiment (SIPEX-2) in late winter 2012. Since logistical reasons limited helicopter operations to two interior ice regions, FSD in the interior ice region was determined using a combination of heli-photos and MODIS satellite visible images. The possible effect of wave-ice interaction in the MIZ was examined by comparison with past results obtained in the same MIZ, with our analysis showing: (1) FSD in the interior ice region is basically scale invariant for both small- (<100 m) and large- (>1 km) scale regimes; (2) although fractal dimensions are quite different between these two regimes, they are both rather close to that in the MIZ; and (3) for floes <100 m in diameter, a regime shift which appeared at 20-40 m in the MIZ is absent. These results indicate that one role of wave-ice interaction is to modulate the FSD that already exists in the interior ice region, rather than directly determine it. The possibilities of floe-floe collisions and storm-induced lead formation are considered as possible formation processes of FSD in the interior pack.

  2. Thermal insulation of the intertidal zone by the ice foot

    NASA Astrophysics Data System (ADS)

    Scrosati, Ricardo; Eckersley, Lindsay K.

    2007-11-01

    Few studies have looked at the ecological significance of the ice foot in intertidal habitats. During the 2007 winter, we quantified the hourly variation of temperature at the intertidal zone and at the upper, dry coast on the southern Gulf of St. Lawrence (Nova Scotia, Canada) using submersible data loggers. While air temperature dropped to - 20 °C at the peak of the winter, intertidal temperature was never below - 7 °C during the winter. In fact, for almost two months when the ice foot was stable, temperature ranged only between - 2.4 °C and - 1.1 °C at the intertidal zone. The intertidal values are higher than published values of lethal temperature for cold-water intertidal invertebrates and seaweeds. Thus, the ice foot may prevent these organisms from experiencing lethal levels of thermal stress, contributing to their long-term persistence in these environmentally stressful habitats.

  3. 36 CFR 13.1304 - Ice fall hazard zones.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Ice fall hazard zones. 13.1304 Section 13.1304 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Kenai Fjords National Park...

  4. 36 CFR 13.1304 - Ice fall hazard zones.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Ice fall hazard zones. 13.1304 Section 13.1304 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Kenai Fjords National Park...

  5. 36 CFR 13.1304 - Ice fall hazard zones.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Ice fall hazard zones. 13.1304 Section 13.1304 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Kenai Fjords National Park...

  6. 36 CFR 13.1304 - Ice fall hazard zones.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Ice fall hazard zones. 13.1304 Section 13.1304 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Kenai Fjords National Park...

  7. 36 CFR 13.1304 - Ice fall hazard zones.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Ice fall hazard zones. 13.1304 Section 13.1304 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Kenai Fjords National Park...

  8. Bulk heat transfer coefficient in the ice-upper ocean system in the ice melt season derived from concentration-temperature relationship

    NASA Astrophysics Data System (ADS)

    Nihashi, Sohey; Ohshima, Kay I.

    2008-06-01

    The bulk heat transfer coefficient in the ice-upper ocean system (Kb) in the ice melt season is estimated by a new method at 18 areas that cover much of the Antarctic seasonal ice zone. The method is based on a model in which ice melting is caused only by heat input through open water and is treated in a bulk fashion in the ice-upper ocean system. Kb is estimated by fitting a convergent curve derived from the model to an observed ice concentration-temperature plot (CT-plot). Estimated Kb is 1.15 ± 0.72 × 10-4 m s-1 on average. If Kb can be expressed by the product of the heat transfer coefficient (ch) and the friction velocity (uτ), ch is 0.0113 ± 0.0055. This value is about two times larger than that estimated at the ice bottom. The relationship between Kb and the geostrophic wind speed (Uw), which is roughly proportional to uτ, shows a significant positive correlation, as expected. Further, Kb seems more likely to be proportional to the square or cube of Uw rather than a linear relationship. Since Kb estimated from our method is associated with ice melting in a bulk fashion in the ice-upper ocean system, this relationship likely indicates both the mixing process of heat in the upper ocean (proportional to uτ3) and the local heat transfer process at the ice-ocean interface (proportional to uτ).

  9. Arctic cyclogenesis at the marginal ice zone: A contributory mechanism for the temperature amplification ?

    NASA Astrophysics Data System (ADS)

    Inoue, J.; Hori, M. E.

    2011-12-01

    Rapid sea-ice retreat over the Arctic Ocean has a leading role in Arctic amplification. The sea-ice extent ramatically recovers during every freezing season, so despite the recent summer sea-ice retreat, there must be extraordinary heat exchange between the lower atmosphere and upper ocean. However, the underlying mechanisms for this remain uncertain. Here we show that autumn frontal cyclogenesis is a crucial event in the Arctic air-sea coupled system. Our shipboard Doppler radar and intensive radiosonde observations at the marginal ice zone detected an explosive frontal cyclogenesis, with coupling between upper and lower tropospheric vortices. The thermal contrast between ocean and ice surfaces is likely favorable to cyclogenesis with an identical life-cycle to that at mid-latitudes. This suggests a northward shift of meridional heat transport. The 1.5 K temperature decrease in the upper ocean after the cold front has passed reveals that a large amount of heat is transported into the atmosphere. This is an invaluable example of the fact that sea ice retreat contributes to polar amplification of surface air temperature increase.

  10. Arctic cyclogenesis at the marginal ice zone: A contributory mechanism for the temperature amplification?

    NASA Astrophysics Data System (ADS)

    Inoue, Jun; Hori, Masatake E.

    2011-06-01

    Rapid sea-ice retreat over the Arctic Ocean has a leading role in Arctic amplification. The sea-ice extent dramatically recovers during every freezing season, so despite the recent summer sea-ice retreat, there must be extraordinary heat exchange between the lower atmosphere and upper ocean. However, the underlying mechanisms for this remain uncertain. Here we show that autumn frontal cyclogenesis is a crucial event in the Arctic air-sea coupled system. Our shipboard Doppler radar and intensive radiosonde observations at the marginal ice zone detected an explosive frontal cyclogenesis, with coupling between upper and lower tropospheric vortices. The thermal contrast between ocean and ice surfaces is likely favorable to cyclogenesis with an identical life-cycle to that at mid-latitudes. This suggests a northward shift of meridional heat transport. The 1.5 K temperature decrease in the upper ocean after the cold front has passed reveals that a large amount of heat is transported into the atmosphere. This is an invaluable example of the fact that sea ice retreat contributes to polar amplification of surface air temperature increase.

  11. Ocean-ice interaction in the marginal ice zone using synthetic aperture radar imagery

    NASA Technical Reports Server (NTRS)

    Liu, Antony K.; Peng, Chich Y.; Weingartner, Thomas J.

    1994-01-01

    Ocean-ice interaction processes in the marginal ice zone (MIZ) by wind, waves, and mesoscale features, such as up/downwelling and eddies are studied using Earth Remote-Sensing Satellite (ERS) 1 synthetic aperture radar (SAR) images and an ocean-ice interaction model. A sequence of seven SAR images of the MIZ in the Chukchi Sea with 3 or 6 days interval are investigated for ice edge advance/retreat. Simultaneous current measurements from the northeast Chukchi Sea, as well as the Barrow wind record, are used to interpret the MIZ dynamics. SAR spectra of waves in ice and ocean waves in the Bering and Chukchi Sea are compared for the study of wave propagation and dominant SAR imaging mechanism. By using the SAR-observed ice edge configuration and wind and wave field in the Chukchi Sea as inputs, a numerical simulation has been performed with the ocean-ice interaction model. After 3 days of wind and wave forcing the resulting ice edge configuration, eddy formation, and flow velocity field are shown to be consistent with SAR observations.

  12. Seasonal circulation under the eastern Ross Ice Shelf, Antarctia

    SciTech Connect

    Hellmer, H.H.; Jacobs, S.S.

    1995-06-15

    An annual cycle of shelf water temperatures and salinities measured at depth near the eastern Ross Ice Shelf front is used to force a two-dimensional thermohaline circulation model adapted to different subice paths in the vicinity of Roosevelt Island. These paths were assumed to have constant water column thicknesses of 160, 200, and 240 m and lengths of 460-800 km. Additional simulations with the longer cavity included a 80-m thick interior water column in order to approximate conditions closer to the grounding line. Model results were compared with other long-term measurements that showed outflow from beneath the ice shelf. Shelf water flowing into the cavity west of Roosevelt Island appears to follow a cyclonic route around the island. The ice shelf base loses mass at a rate of 18-27 cm yr{sup {minus}1}, with seasonal forcing increasing the spatial and temporal variability of circulation and property distributions in the larger cavities. Shallow cavities reduce the influence of shelf water variability with increasing length. Introducing a transient shelf water temperature rise of 0.01{degrees}C yr {sup {minus}1} for 100 years increases the melt rate by 4-5 times. However, this increase is smaller if salinity also decreases over the same period of time, as might be expected from the added meltwater component. 42 refs., 9 figs.

  13. Distinct Seasonal Velocity Patterns Based on Ice-Sheet-Wide Analysis of Greenland Outlet Glaciers

    NASA Astrophysics Data System (ADS)

    Moon, T. A.; Joughin, I. R.; Smith, B. E.; van den Broeke, M. R.; Usher, M.

    2014-12-01

    Mass loss from the Greenland Ice Sheet increased significantly over the last several decades and current mass losses of 260-380 Gt ice/yr contribute 0.7-1.1 mm/yr to global sea-level rise. Greenland mass loss includes ice discharge via marine-terminating outlet glaciers and surface meltwater runoff, the former now making up a third to a half of total ice loss. The magnitude of ice discharge depends in part on ice-flow speed, which has broadly increased since 2000 but varies locally, regionally, and from year to year. Research on a limited set of Greenland glaciers also shows that speeds vary seasonally. However, for much of the west, northwest, and southeast coasts where ice loss is increasing most rapidly, there are few or no records of seasonal velocity variation. Ice velocity is influenced by several key components of the ice-sheet-ocean-climate system: subglacial environment, surface melt and runoff, and ice-ocean interaction at the ice-front (terminus). Thus, knowledge of seasonal velocity patterns is important for predicting annual ice discharge, understanding the effects of increased surface melt on total mass loss, and establishing how ice-flow responds to other climatic changes. We developed 5-year records of seasonal velocity measurements for 55 glaciers around the ice-sheet margin. Among glaciers with significant speed variations, we find three distinct seasonal velocity patterns. One pattern indicates relatively high glacier sensitivity to ice-front position, with seasonal summer speedup sustained through fall. The other two patterns appear to be meltwater controlled and indicate regional differences in which some subglacial systems likely transition seasonally from inefficient, distributed hydrologic networks to efficient, channelized drainage, while others do not. These differences in dominant velocity control mechanisms reveal likely spatiotemporal variations in the dynamic response of the ice sheet to climate change.

  14. Artic ice and drilling structures

    SciTech Connect

    Sodhl, D.S.

    1985-04-01

    The sea ice in the southern Beaufort Sea is examined and subdivided into three zones: the fast ice zone, the seasonal pack-ice zone, an the polar pack ice zone. Each zone requires its own type of system. Existing floating drilling systems include ice-strengthened drill ships, conical drilling systems, and floating ice platforms in deep-water land-fast ice. The development of hydrocarbon resources in the Arctic presents great challenges to engineers, since the structures are required to operate safely under various conditions. Significant progress has yet to be made in understanding the behavior of ice.

  15. Composition, Diversity, and Stability of Microbial Assemblages in Seasonal Lake Ice, Miquelon Lake, Central Alberta

    PubMed Central

    Bramucci, Anna; Han, Sukkyun; Beckers, Justin; Haas, Christian; Lanoil, Brian

    2013-01-01

    The most familiar icy environments, seasonal lake and stream ice, have received little microbiological study. Bacteria and Eukarya dominated the microbial assemblage within the seasonal ice of Miquelon Lake, a shallow saline lake in Alberta, Canada. The bacterial assemblages were moderately diverse and did not vary with either ice depth or time. The closest relatives of the bacterial sequences from the ice included Actinobacteria, Bacteroidetes, Proteobacteria, Verrucomicrobia, and Cyanobacteria. The eukaryotic assemblages were less conserved and had very low diversity. Green algae relatives dominated the eukaryotic gene sequences; however, a copepod and cercozoan were also identified, possibly indicating the presence of complete microbial loop. The persistence of a chlorophyll a peak at 25–30 cm below the ice surface, despite ice migration and brine flushing, indicated possible biological activity within the ice. This is the first study of the composition, diversity, and stability of seasonal lake ice. PMID:24832796

  16. Comparison of icing cloud instruments for 1982-1983 icing season flight program

    NASA Technical Reports Server (NTRS)

    Ide, R. F.; Richter, G. P.

    1984-01-01

    A number of modern and old style liquid water content (LWC) and droplet sizing instruments were mounted on a DeHavilland DHC-6 Twin Otter and operated in natural icing clouds in order to determine their comparative operating characteristics and their limitations over a broad range of conditions. The evaluation period occurred during the 1982-1983 icing season from January to March 1983. Time histories of all instrument outputs were plotted and analyzed to assess instrument repeatability and reliability. Scatter plots were also generated for comparison of instruments. The measured LWC from four instruments differed by as much as 20 percent. The measured droplet size from two instruments differed by an average of three microns. The overall effort demonstrated the need for additional data, and for some means of calibrating these instruments to known standards.

  17. Recent Trends in the Arctic Navigable Ice Season and Links to Atmospheric Circulation

    NASA Astrophysics Data System (ADS)

    Maslanik, J.; Drobot, S.

    2002-12-01

    One of the potential effects of Arctic climate warming is an increase in the navigable ice season, perhaps resulting in development of the Arctic as a major shipping route. The distance from western North American ports to Europe through the Northwest Passage (NWP) or the Northern Sea Route (NSR) is typically 20 to 60 percent shorter than travel through the Panama Canal, while travel between Europe and the Far East may be reduced by as much as three weeks compared to transport through the Suez Canal. An increase in the navigable ice season would also improve commercial opportunities within the Arctic region, such as mineral and oil exploration and tourism, which could potentially expand the economic base of Arctic residents and companies, but which would also have negative environmental impacts. Utilizing daily passive-microwave derived sea ice concentrations, trends and variability in the Arctic navigable ice season are examined from 1979 through 2001. Trend analyses suggest large increases in the length of the navigable ice season in the Kara and Barents seas, the Sea of Okhotsk, and the Beaufort Sea, with decreases in the length of the navigable ice season in the Bering Sea. Interannual variations in the navigable ice season largely are governed by fluctuations in low-frequency atmospheric circulation, although the specific annular modes affecting the length of the navigable ice season vary by region. In the Beaufort and East Siberian seas, variations in the North Atlantic Oscillation/Arctic Oscillation control the navigable ice season, while variations in the East Pacific anomaly play an important role in controlling the navigable ice season in the Kara and Barents seas. In Hudson Bay, the Canadian Arctic Archipelago, and Baffin Bay, interannual variations in the navigable ice season are strongly related to the Pacific Decadal Oscillation.

  18. Seasonal Changes in Mars' North Polar Ice Cap

    NASA Technical Reports Server (NTRS)

    1997-01-01

    These images, which seem to have been taken while NASA's Hubble Space Telescope (HST) was looking directly down on the Martian North Pole, were actually created by assembling mosaics of three sets of images taken by HST in October, 1996 and in January and March, 1997 and projecting them to appear as they would if seen from above the pole. This first mosaic is a view which could not actually be seen in nature because at this season a portion of the pole would have actually been in shadow; the last view, taken near the summer solstice, would correspond to the Midnight Sun on Earth with the pole fully illuminated all day. The resulting polar maps begin at 50 degrees N latitude and are oriented with 0 degrees longitude at the 12 o'clock position. This series of pictures captures the seasonal retreat of Mars' north polar cap.

    October 1996 (early spring in the Northern hemisphere): In this map, assembled from images obtained between Oct. 8 and 15, the cap extends down to 60 degrees N latitude, nearly it's maximum winter extent. (The notches are areas where Hubble data were not available). A thin, comma-shaped cloud of dust can be seen as a salmon-colored crescent at the 7 o'clock position. The cap is actually fairly circular about the geographic pole at this season; the bluish 'knobs' where the cap seems to extend further are actually clouds that occurred near the edges of the three separate sets of images used to make the mosaic.

    January 1997 (mid-spring): Increased warming as spring progresses in the northern hemisphere has sublimated the carbon dioxide ice and frost below 70 degrees north latitude. The faint darker circle inside the cap boundary marks the location of circumpolar sand dunes (see March '97 map); these dark dunes are warmed more by solar heating than are the brighter surroundings, so the surface frost sublimates from the dunes earlier than from the neighboring areas. Particularly evident is the marked hexagonal shape of the polar cap at this season

  19. Insights into the Thwaites Glacier grounding zone from Operation IceBridge aerogravity

    NASA Astrophysics Data System (ADS)

    Tinto, K. J.; Bell, R. E.; Cochran, J. R.; Elieff, S.; Frearson, N.

    2010-12-01

    Operation IceBridge acquired 1500 km of geophysical data, at 10 km spacing, in front of the Thwaites Glacier grounding line during the 2009 season. The gravity anomalies recorded by the survey have been used to model the bathymetry of the sea floor in front of the glacier, an area inaccessible to previous surveys. The resulting map reveals previously unseen detail of the Thwaites grounding zone, as well as the spatial extent of features that were formerly only known as points affecting the ice surface. The modeled bathymetry in front of Thwaites Glacier is marked by an undulating ridge running sub-parallel to the grounding line, 40 km seaward. The highest peak on the ridge is in contact with the overlying ice shelf, hindering its flow. Ridge elevation decreases to the west, with a maximum ridge depth of 850 m and an average relief of 350 m. This is comparable in scale to the recently identified ridge crossing the channel of nearby Pine Island Glacier (Jenkins et al., 2010). The present-day grounding line of Thwaites appears to be marked by a more subdued ridge, in which we have identified a 20 km wide hollow, to a water depth of 1200 m. Our model shows that this hollow corresponds to a landward bight in the grounding line, in the region through which the fast ice flow of Thwaites Glacier is focused. This correlation was not visible on previous, coarser scale maps of the grounding line, and shows a clear relationship between the bathymetry and ice flow. Gravity inversions have been constrained by nearby marine surveys, satellite images of the ice rise at the peak of the ridge and radar and laser data from the IceBridge survey to constrain ice thickness. The absolute values of predicted bathymetry are dependent on the density of the rocks in the subsurface, for example the presence or absence of volcanic material or loose sediments. Some models of the geology of the survey area are also proposed. Uncertainty of underlying geology may account for ~100 m errors in the

  20. 78 FR 12595 - Safety Zone for Ice Conditions; Baltimore Captain of the Port Zone

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-25

    ...) 366-9826. SUPPLEMENTARY INFORMATION: Table of Acronyms DHS Department of Homeland Security FR Federal... the January 17, 2008, issue of the Federal Register (73 FR 3316). 4. Public Meeting We do not now plan... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone for Ice Conditions; Baltimore Captain of...

  1. Ice surface temperatures: seasonal cycle and daily variability from in-situ and satellite observations

    NASA Astrophysics Data System (ADS)

    Madsen, Kristine S.; Dybkjær, Gorm; Høyer, Jacob L.; Nielsen-Englyst, Pia; Rasmussen, Till A. S.; Tonboe, Rasmus T.

    2016-04-01

    Surface temperature is an important parameter for understanding the climate system, including the Polar Regions. Yet, in-situ temperature measurements over ice- and snow covered regions are sparse and unevenly distributed, and atmospheric circulation models estimating surface temperature may have large biases. To change this picture, we will analyse the seasonal cycle and daily variability of in-situ and satellite observations, and give an example of how to utilize the data in a sea ice model. We have compiled a data set of in-situ surface and 2 m air temperature observations over land ice, snow, sea ice, and from the marginal ice zone. 2523 time series of varying length from 14 data providers, with a total of more than 13 million observations, have been quality controlled and gathered in a uniform format. An overview of this data set will be presented. In addition, IST satellite observations have been processed from the Metop/AVHRR sensor and a merged analysis product has been constructed based upon the Metop/AVHRR, IASI and Modis IST observations. The satellite and in-situ observations of IST are analysed in parallel, to characterize the IST variability on diurnal and seasonal scales and its spatial patterns. The in-situ data are used to estimate sampling effects within the satellite observations and the good coverage of the satellite observations are used to complete the geographical variability. As an example of the application of satellite IST data, results will be shown from a coupled HYCOM-CICE ocean and sea ice model run, where the IST products have been ingested. The impact of using IST in models will be assessed. This work is a part of the EUSTACE project under Horizon 2020, where the ice surface temperatures form an important piece of the puzzle of creating an observationally based record of surface temperatures for all corners of the Earth, and of the ESA GlobTemperature project which aims at applying surface temperatures in models in order to

  2. Modeling the seasonal variability of a coupled Arctic ice-ocean system

    NASA Technical Reports Server (NTRS)

    Hakkinen, Sirpa; Mellor, George L.

    1992-01-01

    The seasonal variability of the ice-ocean system in the Arctic Basin and the Norwegian, Greenland, and Barents Seas was modeled using a three-dimensional coupled ice-ocean model developed at Princeton University. The snow-ice model uses a three-level thermodynamic scheme similar to Semtner's (1976), but is extended to include the effect of leads. It is shown that simulations using the climatological monthly forcing fields produce a realistic seasonal variability of the ice cover. The ice thickness had a considerable sensitivity to the choice of the long-wave back radiation scheme, but these effects can be reduced through dynamical factors.

  3. Seasonal Variability in Vadose zone biodegradation at a crude oil pipeline rupture site

    USGS Publications Warehouse

    Sihota, Natasha J.; Trost, Jared J.; Bekins, Barbara; Berg, Andrew M.; Delin, Geoffrey N.; Mason, Brent E.; Warren, Ean; Mayer, K. Ulrich

    2016-01-01

    Understanding seasonal changes in natural attenuation processes is critical for evaluating source-zone longevity and informing management decisions. The seasonal variations of natural attenuation were investigated through measurements of surficial CO2 effluxes, shallow soil CO2 radiocarbon contents, subsurface gas concentrations, soil temperature, and volumetric water contents during a 2-yr period. Surficial CO2 effluxes varied seasonally, with peak values of total soil respiration (TSR) occurring in the late spring and summer. Efflux and radiocarbon data indicated that the fractional contributions of natural soil respiration (NSR) and contaminant soil respiration (CSR) to TSR varied seasonally. The NSR dominated in the spring and summer, and CSR dominated in the fall and winter. Subsurface gas concentrations also varied seasonally, with peak values of CO2 and CH4 occurring in the fall and winter. Vadose zone temperatures and subsurface CO2 concentrations revealed a correlation between contaminant respiration and temperature. A time lag of 5 to 7 mo between peak subsurface CO2 concentrations and peak surface efflux is consistent with travel-time estimates for subsurface gas migration. Periods of frozen soils coincided with depressed surface CO2 effluxes and elevated CO2 concentrations, pointing to the temporary presence of an ice layer that inhibited gas transport. Quantitative reactive transport simulations demonstrated aspects of the conceptual model developed from field measurements. Overall, results indicated that source-zone natural attenuation (SZNA) rates and gas transport processes varied seasonally and that the average annual SZNA rate estimated from periodic surface efflux measurements is 60% lower than rates determined from measurements during the summer.

  4. Shallow methylmercury production in the marginal sea ice zone of the central Arctic Ocean

    PubMed Central

    Heimbürger, Lars-Eric; Sonke, Jeroen E.; Cossa, Daniel; Point, David; Lagane, Christelle; Laffont, Laure; Galfond, Benjamin T.; Nicolaus, Marcel; Rabe, Benjamin; van der Loeff, Michiel Rutgers

    2015-01-01

    Methylmercury (MeHg) is a neurotoxic compound that threatens wildlife and human health across the Arctic region. Though much is known about the source and dynamics of its inorganic mercury (Hg) precursor, the exact origin of the high MeHg concentrations in Arctic biota remains uncertain. Arctic coastal sediments, coastal marine waters and surface snow are known sites for MeHg production. Observations on marine Hg dynamics, however, have been restricted to the Canadian Archipelago and the Beaufort Sea (<79°N). Here we present the first central Arctic Ocean (79–90°N) profiles for total mercury (tHg) and MeHg. We find elevated tHg and MeHg concentrations in the marginal sea ice zone (81–85°N). Similar to other open ocean basins, Arctic MeHg concentration maxima also occur in the pycnocline waters, but at much shallower depths (150–200 m). The shallow MeHg maxima just below the productive surface layer possibly result in enhanced biological uptake at the base of the Arctic marine food web and may explain the elevated MeHg concentrations in Arctic biota. We suggest that Arctic warming, through thinning sea ice, extension of the seasonal sea ice zone, intensified surface ocean stratification and shifts in plankton ecodynamics, will likely lead to higher marine MeHg production. PMID:25993348

  5. Shallow methylmercury production in the marginal sea ice zone of the central Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Heimbürger, Lars-Eric; Sonke, Jeroen E.; Cossa, Daniel; Point, David; Lagane, Christelle; Laffont, Laure; Galfond, Benjamin T.; Nicolaus, Marcel; Rabe, Benjamin; van der Loeff, Michiel Rutgers

    2015-05-01

    Methylmercury (MeHg) is a neurotoxic compound that threatens wildlife and human health across the Arctic region. Though much is known about the source and dynamics of its inorganic mercury (Hg) precursor, the exact origin of the high MeHg concentrations in Arctic biota remains uncertain. Arctic coastal sediments, coastal marine waters and surface snow are known sites for MeHg production. Observations on marine Hg dynamics, however, have been restricted to the Canadian Archipelago and the Beaufort Sea (<79°N). Here we present the first central Arctic Ocean (79-90°N) profiles for total mercury (tHg) and MeHg. We find elevated tHg and MeHg concentrations in the marginal sea ice zone (81-85°N). Similar to other open ocean basins, Arctic MeHg concentration maxima also occur in the pycnocline waters, but at much shallower depths (150-200 m). The shallow MeHg maxima just below the productive surface layer possibly result in enhanced biological uptake at the base of the Arctic marine food web and may explain the elevated MeHg concentrations in Arctic biota. We suggest that Arctic warming, through thinning sea ice, extension of the seasonal sea ice zone, intensified surface ocean stratification and shifts in plankton ecodynamics, will likely lead to higher marine MeHg production.

  6. Shallow methylmercury production in the marginal sea ice zone of the central Arctic Ocean.

    PubMed

    Heimbürger, Lars-Eric; Sonke, Jeroen E; Cossa, Daniel; Point, David; Lagane, Christelle; Laffont, Laure; Galfond, Benjamin T; Nicolaus, Marcel; Rabe, Benjamin; van der Loeff, Michiel Rutgers

    2015-05-20

    Methylmercury (MeHg) is a neurotoxic compound that threatens wildlife and human health across the Arctic region. Though much is known about the source and dynamics of its inorganic mercury (Hg) precursor, the exact origin of the high MeHg concentrations in Arctic biota remains uncertain. Arctic coastal sediments, coastal marine waters and surface snow are known sites for MeHg production. Observations on marine Hg dynamics, however, have been restricted to the Canadian Archipelago and the Beaufort Sea (<79 °N). Here we present the first central Arctic Ocean (79-90 °N) profiles for total mercury (tHg) and MeHg. We find elevated tHg and MeHg concentrations in the marginal sea ice zone (81-85 °N). Similar to other open ocean basins, Arctic MeHg concentration maxima also occur in the pycnocline waters, but at much shallower depths (150-200 m). The shallow MeHg maxima just below the productive surface layer possibly result in enhanced biological uptake at the base of the Arctic marine food web and may explain the elevated MeHg concentrations in Arctic biota. We suggest that Arctic warming, through thinning sea ice, extension of the seasonal sea ice zone, intensified surface ocean stratification and shifts in plankton ecodynamics, will likely lead to higher marine MeHg production.

  7. Prospects for improved seasonal Arctic sea ice predictions from multivariate data assimilation

    NASA Astrophysics Data System (ADS)

    Massonnet, François; Fichefet, Thierry; Goosse, Hugues

    2015-04-01

    Predicting the summer Arctic sea ice conditions a few months in advance has become a challenging priority. Seasonal prediction is partly an initial condition problem; therefore, a good knowledge of the initial sea ice state is necessary to hopefully produce reliable forecasts. Most of the intrinsic memory of sea ice lies in its thickness, but consistent and homogeneous observational networks of sea ice thickness are still limited in space and time. To overcome this problem, we constrain the ocean-sea ice model NEMO-LIM3 with gridded sea ice concentration retrievals from satellite observations using the ensemble Kalman filter. No sea ice thickness products are assimilated. However, thanks to the multivariate formalism of the data assimilation method used, sea ice thickness is globally updated in a consistent way whenever observations of concentration are available. We compare in this paper the skill of 27 pairs of initialized and uninitialized seasonal Arctic sea ice hindcasts spanning 1983-2009, driven by the same atmospheric forcing as to isolate the pure role of initial conditions on the prediction skill. The results exhibit the interest of multivariate sea ice initialization for the seasonal predictions of the September ice concentration and are particularly encouraging for hindcasts in the 2000s. In line with previous studies showing the interest of data assimilation for sea ice thickness reconstruction, our results thus show that sea ice data assimilation is also a promising tool for short-term prediction, and that current seasonal sea ice forecast systems could gain predictive skill from a more realistic sea ice initialization.

  8. Direct observations of ice seasonality reveal changes in climate over the past 320–570 years

    NASA Astrophysics Data System (ADS)

    Sharma, Sapna; Magnuson, John J.; Batt, Ryan D.; Winslow, Luke A.; Korhonen, Johanna; Aono, Yasuyuki

    2016-04-01

    Lake and river ice seasonality (dates of ice freeze and breakup) responds sensitively to climatic change and variability. We analyzed climate-related changes using direct human observations of ice freeze dates (1443–2014) for Lake Suwa, Japan, and of ice breakup dates (1693–2013) for Torne River, Finland. We found a rich array of changes in ice seasonality of two inland waters from geographically distant regions: namely a shift towards later ice formation for Suwa and earlier spring melt for Torne, increasing frequencies of years with warm extremes, changing inter-annual variability, waning of dominant inter-decadal quasi-periodic dynamics, and stronger correlations of ice seasonality with atmospheric CO2 concentration and air temperature after the start of the Industrial Revolution. Although local factors, including human population growth, land use change, and water management influence Suwa and Torne, the general patterns of ice seasonality are similar for both systems, suggesting that global processes including climate change and variability are driving the long-term changes in ice seasonality.

  9. Direct observations of ice seasonality reveal changes in climate over the past 320–570 years

    USGS Publications Warehouse

    Sharma, Sapna; Magnuson, John J.; Batt, Ryan D; Winslow, Luke; Korhonen, Johanna; Yasuyuki Aono,

    2016-01-01

    Lake and river ice seasonality (dates of ice freeze and breakup) responds sensitively to climatic change and variability. We analyzed climate-related changes using direct human observations of ice freeze dates (1443–2014) for Lake Suwa, Japan, and of ice breakup dates (1693–2013) for Torne River, Finland. We found a rich array of changes in ice seasonality of two inland waters from geographically distant regions: namely a shift towards later ice formation for Suwa and earlier spring melt for Torne, increasing frequencies of years with warm extremes, changing inter-annual variability, waning of dominant inter-decadal quasi-periodic dynamics, and stronger correlations of ice seasonality with atmospheric CO2 concentration and air temperature after the start of the Industrial Revolution. Although local factors, including human population growth, land use change, and water management influence Suwa and Torne, the general patterns of ice seasonality are similar for both systems, suggesting that global processes including climate change and variability are driving the long-term changes in ice seasonality.

  10. Direct observations of ice seasonality reveal changes in climate over the past 320–570 years

    PubMed Central

    Sharma, Sapna; Magnuson, John J.; Batt, Ryan D.; Winslow, Luke A.; Korhonen, Johanna; Aono, Yasuyuki

    2016-01-01

    Lake and river ice seasonality (dates of ice freeze and breakup) responds sensitively to climatic change and variability. We analyzed climate-related changes using direct human observations of ice freeze dates (1443–2014) for Lake Suwa, Japan, and of ice breakup dates (1693–2013) for Torne River, Finland. We found a rich array of changes in ice seasonality of two inland waters from geographically distant regions: namely a shift towards later ice formation for Suwa and earlier spring melt for Torne, increasing frequencies of years with warm extremes, changing inter-annual variability, waning of dominant inter-decadal quasi-periodic dynamics, and stronger correlations of ice seasonality with atmospheric CO2 concentration and air temperature after the start of the Industrial Revolution. Although local factors, including human population growth, land use change, and water management influence Suwa and Torne, the general patterns of ice seasonality are similar for both systems, suggesting that global processes including climate change and variability are driving the long-term changes in ice seasonality. PMID:27113125

  11. Direct observations of ice seasonality reveal changes in climate over the past 320-570 years.

    PubMed

    Sharma, Sapna; Magnuson, John J; Batt, Ryan D; Winslow, Luke A; Korhonen, Johanna; Aono, Yasuyuki

    2016-01-01

    Lake and river ice seasonality (dates of ice freeze and breakup) responds sensitively to climatic change and variability. We analyzed climate-related changes using direct human observations of ice freeze dates (1443-2014) for Lake Suwa, Japan, and of ice breakup dates (1693-2013) for Torne River, Finland. We found a rich array of changes in ice seasonality of two inland waters from geographically distant regions: namely a shift towards later ice formation for Suwa and earlier spring melt for Torne, increasing frequencies of years with warm extremes, changing inter-annual variability, waning of dominant inter-decadal quasi-periodic dynamics, and stronger correlations of ice seasonality with atmospheric CO2 concentration and air temperature after the start of the Industrial Revolution. Although local factors, including human population growth, land use change, and water management influence Suwa and Torne, the general patterns of ice seasonality are similar for both systems, suggesting that global processes including climate change and variability are driving the long-term changes in ice seasonality.

  12. Direct observations of ice seasonality reveal changes in climate over the past 320-570 years.

    PubMed

    Sharma, Sapna; Magnuson, John J; Batt, Ryan D; Winslow, Luke A; Korhonen, Johanna; Aono, Yasuyuki

    2016-01-01

    Lake and river ice seasonality (dates of ice freeze and breakup) responds sensitively to climatic change and variability. We analyzed climate-related changes using direct human observations of ice freeze dates (1443-2014) for Lake Suwa, Japan, and of ice breakup dates (1693-2013) for Torne River, Finland. We found a rich array of changes in ice seasonality of two inland waters from geographically distant regions: namely a shift towards later ice formation for Suwa and earlier spring melt for Torne, increasing frequencies of years with warm extremes, changing inter-annual variability, waning of dominant inter-decadal quasi-periodic dynamics, and stronger correlations of ice seasonality with atmospheric CO2 concentration and air temperature after the start of the Industrial Revolution. Although local factors, including human population growth, land use change, and water management influence Suwa and Torne, the general patterns of ice seasonality are similar for both systems, suggesting that global processes including climate change and variability are driving the long-term changes in ice seasonality. PMID:27113125

  13. Processes and imagery of first-year fast sea ice during the melt season

    NASA Technical Reports Server (NTRS)

    Holt, B.; Digby, S. A.

    1985-01-01

    In June and July 1982, a field program was conducted in the Canadian Arctic on Prince Patrick Island to study sea ice during the melt season with in situ measurements and microwave instrumentation operated near the surface and from aircraft. The objective of the program was to measure physical characteristics together with microwave backscatter and emission coefficients of sea ice during this major period of transition. The present paper is concerned with a study of both surface measurements and imagery of first-year fast ice during the melt season. The melting process observed in first-year fast ice was found to begin with the gradual reduction of the snow cover. For a two- to three-day period in this melt stage, a layer of superimposed ice nodules formed at the snow/ice interface as meltwater froze around ice and snow grains.

  14. Influence of timing of sea ice retreat on phytoplankton size during marginal ice zone bloom period in the Chukchi and Bering shelves

    NASA Astrophysics Data System (ADS)

    Fujiwara, A.; Hirawake, T.; Suzuki, K.; Eisner, L.; Imai, I.; Nishino, S.; Kikuchi, T.; Saitoh, S. I.

    2015-08-01

    Timing of sea ice retreat (TSR) as well as cell size of primary producers (i.e., phytoplankton) plays crucial roles in seasonally ice-covered marine ecosystem. Thus, it is important to monitor the temporal and spatial distribution of phytoplankton community size structure. Prior to this study, an ocean color algorithm has been developed to derive phytoplankton size index FL, which is defined as the ratio of chlorophyll a derived from the cells larger than 5 μm to the total chl a using satellite remote sensing for the Chukchi and Bering shelves. Using this method, we analyzed pixel-by-pixel relationships between FL during marginal ice zone (MIZ) bloom period and TSR over a period of 1998-2013. The influence of TSR on sea surface temperature (SST) and changes in ocean heat content (ΔOHC) during the MIZ bloom period were also investigated. A significant negative relationship between FL and TSR was widely found in the shelf region during MIZ bloom season. On the other hand, we found a significant positive (negative) relationship between SST (ΔOHC) and TSR. That is, earlier sea-ice retreat was associated with a dominance of larger phytoplankton during a colder and weakly stratified MIZ bloom season, suggesting that duration of nitrate supply, which is important for large-sized phytoplankton growth in this region (i.e., diatoms), can change according to TSR. In addition, under-ice phytoplankton blooms are likely to occur in years with late ice retreat, because sufficient light for phytoplankton growth can pass through the ice and penetrate into the water columns due to an increase in solar radiation toward the summer solstice. Moreover, we found not only the length of ice-free season but also annual median of FL positively correlated with annual net primary production (APP). Thus, both phytoplankton community composition and growing season are important for APP in the study area. Our findings showed quantitative relationship between the inter-annual variability of FL

  15. Influence of timing of sea ice retreat on phytoplankton size during marginal ice zone bloom period on the Chukchi and Bering shelves

    NASA Astrophysics Data System (ADS)

    Fujiwara, A.; Hirawake, T.; Suzuki, K.; Eisner, L.; Imai, I.; Nishino, S.; Kikuchi, T.; Saitoh, S.-I.

    2016-01-01

    The size structure and biomass of a phytoplankton community during the spring bloom period can affect the energy use of higher-trophic-level organisms through the predator-prey body size relationships. The timing of the sea ice retreat (TSR) also plays a crucial role in the seasonally ice-covered marine ecosystem, because it is tightly coupled with the timing of the spring bloom. Thus, it is important to monitor the temporal and spatial distributions of a phytoplankton community size structure. Prior to this study, an ocean colour algorithm was developed to derive phytoplankton size index FL, which is defined as the ratio of chlorophyll a (chl a) derived from cells larger than 5 µm to the total chl a, using satellite remote sensing for the Chukchi and Bering shelves. Using this method, we analysed the pixel-by-pixel relationships between FL during the marginal ice zone (MIZ) bloom period and TSR over the period of 1998-2013. The influences of the TSR on the sea surface temperature (SST) and changes in ocean heat content (ΔOHC) during the MIZ bloom period were also investigated. A significant negative relationship between FL and the TSR was widely found in the shelf region during the MIZ bloom season. However, we found a significant positive (negative) relationship between the SST (ΔOHC) and TSR. Specifically, an earlier sea ice retreat was associated with the dominance of larger phytoplankton during a colder and weakly stratified MIZ bloom season, suggesting that the duration of the nitrate supply, which is important for the growth of large-sized phytoplankton in this region (i.e. diatoms), can change according to the TSR. In addition, under-ice phytoplankton blooms are likely to occur in years with late ice retreat, because sufficient light for phytoplankton growth can pass through the ice and penetrate into the water columns as a result of an increase in solar radiation toward the summer solstice

  16. CO2 jets formed by sublimation beneath translucent slab ice in Mars' seasonal south polar ice cap

    USGS Publications Warehouse

    Kieffer, H.H.; Christensen, P.R.; Titus, T.N.

    2006-01-01

    The martian polar caps are among the most dynamic regions on Mars, growing substantially in winter as a significant fraction of the atmosphere freezes out in the form of CO2 ice. Unusual dark spots, fans and blotches form as the south-polar seasonal CO2 ice cap retreats during spring and summer. Small radial channel networks are often associated with the location of spots once the ice disappears. The spots have been proposed to be simply bare, defrosted ground; the formation of the channels has remained uncertain. Here we report infrared and visible observations that show that the spots and fans remain at CO2 ice temperatures well into summer, and must be granular materials that have been brought up to the surface of the ice, requiring a complex suite of processes to get them there. We propose that the seasonal ice cap forms an impermeable, translucent slab of CO2 ice that sublimates from the base, building up high-pressure gas beneath the slab. This gas levitates the ice, which eventually ruptures, producing high-velocity CO 2 vents that erupt sand-sized grains in jets to form the spots and erode the channels. These processes are unlike any observed on Earth. ?? 2006 Nature Publishing Group.

  17. CO2 jets formed by sublimation beneath translucent slab ice in Mars' seasonal south polar ice cap.

    PubMed

    Kieffer, Hugh H; Christensen, Philip R; Titus, Timothy N

    2006-08-17

    The martian polar caps are among the most dynamic regions on Mars, growing substantially in winter as a significant fraction of the atmosphere freezes out in the form of CO2 ice. Unusual dark spots, fans and blotches form as the south-polar seasonal CO2 ice cap retreats during spring and summer. Small radial channel networks are often associated with the location of spots once the ice disappears. The spots have been proposed to be simply bare, defrosted ground; the formation of the channels has remained uncertain. Here we report infrared and visible observations that show that the spots and fans remain at CO2 ice temperatures well into summer, and must be granular materials that have been brought up to the surface of the ice, requiring a complex suite of processes to get them there. We propose that the seasonal ice cap forms an impermeable, translucent slab of CO2 ice that sublimates from the base, building up high-pressure gas beneath the slab. This gas levitates the ice, which eventually ruptures, producing high-velocity CO2 vents that erupt sand-sized grains in jets to form the spots and erode the channels. These processes are unlike any observed on Earth.

  18. Polygonal cracks in the seasonal semi-translucent CO2 ice layer in Martian polar areas

    NASA Astrophysics Data System (ADS)

    Portyankina, Ganna; Pommerol, Antoine; Aye, Klaus-Michael; Hansen, Candice J.; Thomas, Nicolas

    2012-02-01

    In this paper, we use morphological and numerical methods to test the hypothesis that seasonally formed fracture patterns in the Martian polar regions result from the brittle failure of seasonal CO2 slab ice. The observations by the High Resolution Imaging Science Experiment (HiRISE) of polar regions of Mars show very narrow dark elongated linear patterns that are observed during some periods of time in spring, disappear in summer and re-appear again in the following spring. They are repeatedly formed in the same areas but they do not repeat the exact pattern from year to year. This leads to the conclusion that they are cracks formed in the seasonal ice layer. Some of models of seasonal surface processes rely on the existence of a transparent form of CO2 ice, so-called slab ice. For the creation of the observed cracks the ice is required to be a continuous media, not an agglomeration of relatively separate particles like a firn. The best explanation for our observations is a slab ice with relatively high transparency in the visible wavelength range. This transparency allows a solid state green-house effect to act underneath the ice sheet raising the pressure by sublimation from below. The trapped gas creates overpressure and the ice sheet breaks at some point creating the observed cracks. We show that the times when the cracks appear are in agreement with the model calculation, providing one more piece of evidence that CO2 slab ice covers polar areas in spring.

  19. Variations in the Sea Ice Edge and the Marginal Ice Zone on Different Spatial Scales as Observed from Different Satellite Sensor

    NASA Technical Reports Server (NTRS)

    Markus, Thorsten; Henrichs, John

    2006-01-01

    and volume scattering characteristics. The Canadian RADARSAT C-band SAR provides data that cover the Arctic Ocean and the MIZ every 3 days. A change-point detection approach was utilized to obtain an ice edge estimate from the RADARSAT data The Quickscat scatterometer provides ice edge information with a resolution of a few kilometers on a near-daily basis. During portions of March and April of 2003 a series of aircraft flights were conducted over the ice edge in the Bering Sea carrying the Polarimetric Scanning Radiometer (PSR), which provides spectral coverage identical with the AMSR-E instrument at a resolution of 500 meters. In this study we investigated these different data sets and analyzed differences in their definition of the sea ice edge and the marginal ice zone and how these differences as well as their individual limitations affect the monitoring of the ice edge dynamics. We also examined how the nature of the sea ice edge, including its location, compactness and shape, changes over the seasons. Our approach was based on calculation of distances between ice edges derived from the satellite and aircraft data sets listed above as well as spectral coherence methods and shape parameters such as tortuosity, curvature, and fractional dimension.

  20. Dynamics of coupled ice-ocean system in the marginal ice zone: Study of the mesoscale processes and of constitutive equations for sea ice

    NASA Technical Reports Server (NTRS)

    Hakkinen, S.

    1984-01-01

    This study is aimed at the modelling of mesoscale processed such as up/downwelling and ice edge eddies in the marginal ice zones. A 2-dimensional coupled ice-ocean model is used for the study. The ice model is coupled to the reduced gravity ocean model (f-plane) through interfacial stresses. The constitutive equations of the sea ice are formulated on the basis of the Reiner-Rivlin theory. The internal ice stresses are important only at high ice concentrations (90-100%), otherwise the ice motion is essentially free drift, where the air-ice stress is balanced by the ice-water stress. The model was tested by studying the upwelling dynamics. Winds parallel to the ice edge with the ice on the right produce upwilling because the air-ice momentum flux is much greater that air-ocean momentum flux, and thus the Ekman transport is bigger under the ice than in the open water. The upwelling simulation was extended to include temporally varying forcing, which was chosen to vary sinusoidally with a 4 day period. This forcing resembles successive cyclone passings. In the model with a thin oceanic upper layer, ice bands were formed.

  1. Seasonal development of the properties and composition of landfast sea ice in the Gulf of Finland, the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Granskog, Mats A.; LeppäRanta, Matti; Kawamura, Toshiyuki; Ehn, Jens; Shirasawa, Kunio

    2004-02-01

    The seasonal development of the structure, salinity, and stable oxygen isotopic composition (δ18O) of landfast sea ice was studied during the winter seasons 1999-2001 in the Gulf of Finland in the Baltic Sea. The main focuses were on the seasonal and the interannual variability in ice properties and composition and on the contribution of meteoric ice to sea ice mass balance. Results provide a first statistical description of the seasonal evolution of sea ice in mild ice climate conditions. The ice has a characteristic structure with an upper granular ice layer, composed almost exclusively of superimposed ice and snow-ice, averaging at 20-35% of the total ice thickness. The remaining is composed of columnar or intermediate granular columnar ice, depending on growth conditions. While salinity shows a uniform profile through the ice, δ18O shows lower values in the surface because of meteoric ice formation. The thin ice cover is susceptible to changes in atmospheric conditions, and rapid changes in ice salinity are connected to changes in the ice thermal regime and flooding. The contribution of meteoric ice varied from 0 to 35% (by mass), depending on season and year. Superimposed ice formation is a recurring process and significantly contributed to ice growth (up to 20% by mass), especially late in the season during snowmelt-freeze cycles. Liquid precipitation also cause formation of intermittent superimposed ice layers at these latitudes. The contribution of meteoric ice to sea ice mass balance is largely dependent on the amount and timing of snow accumulation and timing of snowmelt-freeze processes, which all showed large year-to-year variation. The conditions presented here may start to occur at higher latitudes if global warming continues.

  2. Bacterial communities from Arctic seasonal sea ice are more compositionally variable than those from multi-year sea ice.

    PubMed

    Hatam, Ido; Lange, Benjamin; Beckers, Justin; Haas, Christian; Lanoil, Brian

    2016-10-01

    Arctic sea ice can be classified into two types: seasonal ice (first-year ice, FYI) and multi-year ice (MYI). Despite striking differences in the physical and chemical characteristics of FYI and MYI, and the key role sea ice bacteria play in biogeochemical cycles of the Arctic Ocean, there are a limited number of studies comparing the bacterial communities from these two ice types. Here, we compare the membership and composition of bacterial communities from FYI and MYI sampled north of Ellesmere Island, Canada. Our results show that communities from both ice types were dominated by similar class-level phylogenetic groups. However, at the operational taxonomic unit (OTU) level, communities from MYI and FYI differed in both membership and composition. Communities from MYI sites had consistent structure, with similar membership (presence/absence) and composition (OTU abundance) independent of location and year of sample. By contrast, communities from FYI were more variable. Although FYI bacterial communities from different locations and different years shared similar membership, they varied significantly in composition. Should these findings apply to sea ice across the Arctic, we predict increased compositional variability in sea ice bacterial communities resulting from the ongoing transition from predominantly MYI to FYI, which may impact nutrient dynamics in the Arctic Ocean. PMID:26882269

  3. Bacterial communities from Arctic seasonal sea ice are more compositionally variable than those from multi-year sea ice.

    PubMed

    Hatam, Ido; Lange, Benjamin; Beckers, Justin; Haas, Christian; Lanoil, Brian

    2016-10-01

    Arctic sea ice can be classified into two types: seasonal ice (first-year ice, FYI) and multi-year ice (MYI). Despite striking differences in the physical and chemical characteristics of FYI and MYI, and the key role sea ice bacteria play in biogeochemical cycles of the Arctic Ocean, there are a limited number of studies comparing the bacterial communities from these two ice types. Here, we compare the membership and composition of bacterial communities from FYI and MYI sampled north of Ellesmere Island, Canada. Our results show that communities from both ice types were dominated by similar class-level phylogenetic groups. However, at the operational taxonomic unit (OTU) level, communities from MYI and FYI differed in both membership and composition. Communities from MYI sites had consistent structure, with similar membership (presence/absence) and composition (OTU abundance) independent of location and year of sample. By contrast, communities from FYI were more variable. Although FYI bacterial communities from different locations and different years shared similar membership, they varied significantly in composition. Should these findings apply to sea ice across the Arctic, we predict increased compositional variability in sea ice bacterial communities resulting from the ongoing transition from predominantly MYI to FYI, which may impact nutrient dynamics in the Arctic Ocean.

  4. Midwater food web in the vicinity of a marginal ice zone in the western Weddell Sea

    NASA Astrophysics Data System (ADS)

    Hopkins, Thomas L.; Torres, Joseph J.

    1989-04-01

    The structure of the food web in the vicinity of a marginal ice zone was investigated in the western Weddell Sea during austral autumn 1986. The diets of 40 species of zooplankton and micronekton occurring in the epipelagic zone were examined and compared using non-hierarchical clustering procedures. Over half the species were in three clusters of predominantly small-particle (phytoplankton; protozoans) grazers. These included biomass dominants Calanoides acutus, Calanus propinquus, Metridia gerlachei and Salpa thompsoni. Six clusters contained omnivores that had diets consisting of small particles as well as a substantial fraction of metazoan food. Among these was Euphausia superba. Seven groups were carnivorous, including species of copepods (1), chaetognaths (3), and fishes (5). Copepods were the most frequent food of carnivores; however krill also were important in the diets of three fish species. Among small-particle grazers, phytoplankton occurred more frequently in guts of individuals from open water; carnivory was more in evidence in samples collected under the pack ice. Regional comparisons of material taken on this and several previous cruises indicate that, in most of the dominant species, diets remain relatively consistent with respect to major food categories. Seasonal impact on feeding dynamics appears to be great: the guts of grazing species were generally much more full (visual evidence) during summer bloom conditions than during the autumn. The following trophic sequence is suggested for grazing zooplankton species in ice-covered regions of the Antarctic: (1) Active small-particle grazing during the summer bloom period; (2) reduced ingestion rates in autumn as primary production declines and the system becomes more oligotrophic, with some species augmenting grazing with carnivory; (3) descent of zooplankton biomass species into the mesopelagic zone in late autumn-early winter with feeding largely terminated. The sequence applies to the dominant

  5. On the drivers of phytoplankton blooms in the Antarctic marginal ice zone: A modeling approach

    NASA Astrophysics Data System (ADS)

    Taylor, Marc H.; Losch, Martin; Bracher, Astrid

    2013-01-01

    Abstract The pelagic province of the Southern Ocean generally has low levels of primary production attributable to a short growing <span class="hlt">season</span> in the higher latitudes, a deep mixed layer, and iron limitation. Exceptions include phytoplankton blooms in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> (MIZ) during spring and summer sea-<span class="hlt">ice</span> retreat. The prevailing hypothesis as to the drivers of the blooms is that sea-<span class="hlt">ice</span> retreat increases the vertical stability of the water column through the production of melt water and provides shelter from wind mixing in areas of partial sea-<span class="hlt">ice</span> coverage. These conditions are favorable to phytoplankton growth by allowing them to maintain their position in the upper reaches of the water column. This work investigates the drivers of MIZ blooms using a biochemically coupled global circulation model. Results support the hypothesis in that physical conditions related to a shallow, vertically stable water column (e.g., mixed layer depth and available light) were the most significant predictors of bloom dynamics, while nutrient limitation was of lesser importance. We estimate that MIZ blooms account for 15% of yearly net primary production in the Southern Ocean and that the earlier phases of the MIZ bloom, occurring under partial <span class="hlt">ice</span> coverage and invisible to remote sensing, account for about two thirds of this production. MIZ blooms were not found to enhance depth-integrated net primary production when compared to similar ecological provinces outside of the MIZ, although the elevated phytoplankton concentrations in surface waters are hypothesized to provide important feeding habitats for grazing organisms such as krill.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870066726&hterms=zones+ocean&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dzones%2Bocean','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870066726&hterms=zones+ocean&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dzones%2Bocean"><span id="translatedtitle">A coupled dynamic-thermodynamic model of an <span class="hlt">ice</span>-ocean system in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hakkinen, Sirpa</p> <p>1987-01-01</p> <p>Thermodynamics are incorporated into a coupled <span class="hlt">ice</span>-ocean model in order to investigate wind-driven <span class="hlt">ice</span>-ocean processes in the marginal <span class="hlt">zone</span>. Upswelling at the <span class="hlt">ice</span> edge which is generated by the difference in the <span class="hlt">ice</span>-air and air-water surface stresses is found to give rise to a strong entrainment by drawing the pycnocline closer to the surface. Entrainment is shown to be negligible outside the areas affected by the <span class="hlt">ice</span> edge upswelling. If cooling at the top is included in the model, the heat and salt exchanges are further enhanced in the upswelling areas. It is noted that new <span class="hlt">ice</span> formation occurs in the region not affected by <span class="hlt">ice</span> edge upswelling, and it is suggested that the high-salinity mixed layer regions (with a scale of a few Rossby radii of deformation) will overturn due to cooling, possibly contributing to the formation of deep water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.P23A1691M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.P23A1691M"><span id="translatedtitle">Martian <span class="hlt">Seasonal</span> CO2 Frost Indicating Decameter-Scale Variability in Buried Water <span class="hlt">Ice</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mellon, M. T.; Hansen, C. J.; Cull, S.; Arvidson, R. E.; Searls, M.</p> <p>2011-12-01</p> <p>Several new lines of evidence indicate that subsurface water <span class="hlt">ice</span> (ground <span class="hlt">ice</span>) on Mars is more complexly distributed, and in variable concentrations, than had been previously envisioned. Understanding the current distribution of ground <span class="hlt">ice</span> is a fundamental part of understanding how this <span class="hlt">ice</span> was emplaced and the recent past climate conditions under which icy deposits formed and subsequently evolved. In this work we examine the <span class="hlt">seasonal</span> defrosting of CO2 observed by HiRISE as an indicator of decameter-scale ground-<span class="hlt">ice</span> heterogeneity. It is well known that CO2 dry <span class="hlt">ice</span> accumulates on the martian surface in winter. The amount of dry <span class="hlt">ice</span> and the time it spends on the ground depends strongly on surface properties. A readily observable attribute is the "crocus date", the <span class="hlt">season</span> (Ls) when CO2 completely sublimates, exposing the soil surface. Many factors can affect the crocus date, but perhaps most important are the properties of CO2 frost and of the surface soil. We examine HiRISE observations, spanning more than a martian year, for decameter-scale patterns of CO2 frost and the crocus date. Year-to-year repeatability of CO2 <span class="hlt">ice</span> patterns, both in polygon troughs and decameter-size patches, along with a lack of topography nor aeolian redistribution, suggests that differences in the surface substrate is the root cause for these patterns. In addition, only CO2 slab <span class="hlt">ice</span> (solid, non-porous dry <span class="hlt">ice</span>) is indicated throughout the observed <span class="hlt">seasons</span> and at all spatial scales (down to meter scale), as evidenced by albedo (HiRISE and TES) and IR spectra (CRISM). In addition, the low emissivity and high albedo of fine-grained particulate CO2 frost would result in a crocus date much earlier than even the earliest observed. We present two scenarios of substrate differences which explain the observations: (i) the <span class="hlt">ice</span>-table depth varies away from atmospheric equilibrium, such that a thicker "dry-soil" layer occurs in disequilibrium where the CO2 <span class="hlt">ice</span> lingers longest; and (ii) the H2O</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-01-13/pdf/2012-616.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-01-13/pdf/2012-616.pdf"><span id="translatedtitle">77 FR 2017 - Safety <span class="hlt">Zone</span>; <span class="hlt">Ice</span> Rescue Exercise; Green Bay, Dyckesville, WI</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-01-13</p> <p>... SECURITY Coast Guard 33 CFR PART 165 RIN 1625-AA00 Safety <span class="hlt">Zone</span>; <span class="hlt">Ice</span> Rescue Exercise; Green Bay, Dyckesville... restrict vessels and persons from a portion of Green Bay due to a large scale <span class="hlt">ice</span> rescue exercise that will... surrounding public and vessels from the hazards associated with the <span class="hlt">ice</span> rescue exercise. DATES: This rule...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950050449&hterms=parkinson&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dparkinson','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950050449&hterms=parkinson&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dparkinson"><span id="translatedtitle">Spatial patterns in the length of the sea <span class="hlt">ice</span> <span class="hlt">season</span> in the Southern Ocean, 1979-1986</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parkinson, Claire L.</p> <p>1994-01-01</p> <p>The length of the sea <span class="hlt">ice</span> <span class="hlt">season</span> summarizes in one number the <span class="hlt">ice</span> coverage conditions for an individual location for an entire year. It becomes a particularly valuable variable when mapped spatially over a large area and examined for regional and interannual differences, as is done here for the Southern Ocean over the years 1979-1986, using the satellite passive microwave data of the Nimbus 7 scanning multichannel microwave radiometer. Three prominent geographic anomalies in <span class="hlt">ice</span> <span class="hlt">season</span> lengths occur consistently in each year of the data set, countering the general tendency toward shorter <span class="hlt">ice</span> <span class="hlt">seasons</span> from south to north: (1) in the Weddell Sea the tendency is toward shorter <span class="hlt">ice</span> <span class="hlt">seasons</span> from southwest to northeast, reflective of the cyclonic <span class="hlt">ice</span>/atmosphere/ocean circulations in the Weddell Sea region. (2) Directly north of the Ross <span class="hlt">Ice</span> Shelf anomalously short <span class="hlt">ice</span> <span class="hlt">seasons</span> occur, lasting only 245-270 days, in contrast to the perennial <span class="hlt">ice</span> coverage at comparable latitudes in the southern Bellingshausen and Amundsen Seas and in the western Weddell Sea. The short <span class="hlt">ice</span> <span class="hlt">season</span> off the Ross <span class="hlt">Ice</span> Shelf reflects the consistently early opening of the <span class="hlt">ice</span> cover each spring, under the influence of upwelling along the continental slope and shelf and atmospheric forcing from winds blowing off the Antarctic continent. (3) In the southern Amundsen Sea, anomalously short <span class="hlt">ice</span> <span class="hlt">seasons</span> occur adjacent to the coast, owing to the frequent existence of coastal polynyas off the many small <span class="hlt">ice</span> shelves bordering the sea. Least squares trends in the <span class="hlt">ice</span> <span class="hlt">season</span> lengths over the 1979-1986 period are highly coherent spatially, with overall trends toward shorter <span class="hlt">ice</span> <span class="hlt">seasons</span> in the northern Weddell and Bellingshausen seas and toward longer <span class="hlt">ice</span> <span class="hlt">seasons</span> in the Ross Sea, around much of East Antarctica, and in a portion of the south central Weddell Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5746494','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5746494"><span id="translatedtitle">Current trends in <span class="hlt">seasonal</span> <span class="hlt">ice</span> storage. [Compilation of projects</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gorski, A.J.</p> <p>1986-05-01</p> <p>This document is a compilation of modern research projects focused upon the use of naturally grown winter <span class="hlt">ice</span> for summer cooling applications. Unlike older methods of <span class="hlt">ice</span>-based cooling, in which <span class="hlt">ice</span> was cut from rivers and lakes and transported to insulated icehouses, modern techniques grow <span class="hlt">ice</span> directly in storage containers - by means of heat pipes, snow machines, and water sprays - at the site of application. This modern adaptation of an old idea was reinvented independently at several laboratories in the United States and Canada. Applications range from air conditioning and food storage to desalinization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1815456T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1815456T"><span id="translatedtitle">High-resolution wave forecasting system for the <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered Baltic Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tuomi, Laura; Lehtiranta, Jonni</p> <p>2016-04-01</p> <p>When forecasting surface waves in <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered seas, the inclusion of <span class="hlt">ice</span> conditions in the modelling is important. The <span class="hlt">ice</span> cover affects the propagation and also changes the fetch over which the waves grow. In wave models the <span class="hlt">ice</span> conditions are often still given as a boundary condition and handled by excluding areas where the <span class="hlt">ice</span> concentration exceeds a certain threshold value. The <span class="hlt">ice</span> data used are typically based on satellite analysis or expert analysis of local <span class="hlt">Ice</span> Services who combine data from different sources. This type of data is sufficiently accurate to evaluate the near-real time <span class="hlt">ice</span> concentrations, but when making forecasts it is also important to account for the possible changes in <span class="hlt">ice</span> conditions. For example in a case of a high wind situation, there can be rapid changes in the <span class="hlt">ice</span> field, when the wind and waves may push the <span class="hlt">ice</span> towards shores and cause fragmentation of <span class="hlt">ice</span> field. To enhance handling of <span class="hlt">ice</span> conditions in the Baltic Sea wave forecasts, utilisation of <span class="hlt">ice</span> model data was studied. <span class="hlt">Ice</span> concentration, thickness produced by FMI's operational <span class="hlt">ice</span> model HELMI were used to provide <span class="hlt">ice</span> data to wave model as follows: Wave model grid points where the <span class="hlt">ice</span> concentration was more than or equal to 70% and the <span class="hlt">ice</span> thickness more than1 cm, were excluded from calculations. <span class="hlt">Ice</span> concentrations smaller than that were taken into account as additional grid obstructions by decreasing the wave energy passed from one grid cell to another. A challenge in evaluating wave forecast accuracy in partly <span class="hlt">ice</span> covered areas it that there's typically no wave buoy data available, since the buoys have to be recovered well before the sea area freezes. To evaluate the accuracy of wave forecast in partially <span class="hlt">ice</span> covered areas, significant wave heights from altimeter's ERS2, Envisat, Jason-1 and Jason-2 were extracted from Ifremer database. Results showed that the more frequent update of the <span class="hlt">ice</span> data was found to improve the wave forecast especially during high wind</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ThApC.106..403B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ThApC.106..403B"><span id="translatedtitle"><span class="hlt">Seasonal</span> reversal at Miryang Eoreumgol (<span class="hlt">Ice</span> Valley), Korea: observation and monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Byun, Hi-Ryong; Tanaka, Hiroshi L.; Choi, Pom-Yong; Kim, Do-Woo</p> <p>2011-12-01</p> <p>We investigate an anomalous phenomenon evident in the Miryang Eoreumgol (<span class="hlt">Ice</span> Valley), Korea: The wind and water are cold during summer and warm during winter, and <span class="hlt">ice</span> formation does not occur in winter but in summer. We have initiated observations and investigations into the origin of heat sources particularly with regard to the mechanism of <span class="hlt">ice</span> formation in summer. Previous theories, e.g., concerning underground gravity currents, water evaporation, diurnal and <span class="hlt">seasonal</span> respirations of the talus, effects of ground heat, radiation and topography, etc., are considered. After a calculation of heat sources, we propose two new concepts—a repetitious heat separation mechanism and a positive feedback mechanism of cold air generation—to demonstrate that the heat mechanism of the <span class="hlt">seasonal</span> reversal of the <span class="hlt">ice</span> valley may be controlled by the use of the phase change between <span class="hlt">ice</span> and water vapor with only a small amount of additional unknown energy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C51A0663S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C51A0663S"><span id="translatedtitle">Short-term sea <span class="hlt">ice</span> forecasts with the RASM-ESRL coupled model: A testbed for improving simulations of ocean-<span class="hlt">ice</span>-atmosphere interactions in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Solomon, A.; Cox, C. J.; Hughes, M.; Intrieri, J. M.; Persson, O. P. G.</p> <p>2015-12-01</p> <p>The dramatic decrease of Arctic sea-<span class="hlt">ice</span> has led to a new Arctic sea-<span class="hlt">ice</span> paradigm and to increased commercial activity in the Arctic Ocean. NOAA's mission to provide accurate and timely sea-<span class="hlt">ice</span> forecasts, as explicitly outlined in the National Ocean Policy and the U.S. National Strategy for the Arctic Region, needs significant improvement across a range of time scales to improve safety for human activity. Unfortunately, the sea-<span class="hlt">ice</span> evolution in the new Arctic involves the interaction of numerous physical processes in the atmosphere, <span class="hlt">ice</span>, and ocean, some of which are not yet understood. These include atmospheric forcing of sea-<span class="hlt">ice</span> movement through stress and stress deformation; atmospheric forcing of sea-<span class="hlt">ice</span> melt and formation through energy fluxes; and ocean forcing of the atmosphere through new regions of <span class="hlt">seasonal</span> heat release. Many of these interactions involve emerging complex processes that first need to be understood and then incorporated into forecast models in order to realize the goal of useful sea-<span class="hlt">ice</span> forecasting. The underlying hypothesis for this study is that errors in simulations of "fast" atmospheric processes significantly impact the forecast of <span class="hlt">seasonal</span> sea-<span class="hlt">ice</span> retreat in summer and its advance in autumn in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> (MIZ). We therefore focus on short-term (0-20 day) <span class="hlt">ice</span>-floe movement, the freeze-up and melt-back processes in the MIZ, and the role of storms in modulating stress and heat fluxes. This study uses a coupled ocean-atmosphere-seaice forecast model as a testbed to investigate; whether ocean-sea <span class="hlt">ice</span>-atmosphere coupling improves forecasts on subseasonal time scales, where systematic biases develop due to inadequate parameterizations (focusing on mixed-phase clouds and surface fluxes), how increased atmospheric resolution of synoptic features improves the forecasts, and how initialization of sea <span class="hlt">ice</span> area and thickness and snow depth impacts the skill of the forecasts. Simulations are validated with measurements at pan-Arctic land</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRF..119..588M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRF..119..588M"><span id="translatedtitle">The structure and effect of suture <span class="hlt">zones</span> in the Larsen C <span class="hlt">Ice</span> Shelf, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McGrath, Daniel; Steffen, Konrad; Holland, Paul R.; Scambos, Ted; Rajaram, Harihar; Abdalati, Waleed; Rignot, Eric</p> <p>2014-03-01</p> <p><span class="hlt">Ice</span> shelf fractures frequently terminate where they encounter suture <span class="hlt">zones</span>, regions of material heterogeneity that form between meteoric inflows in <span class="hlt">ice</span> shelves. This heterogeneity can consist of marine <span class="hlt">ice</span>, meteoric <span class="hlt">ice</span> with modified rheological properties, or the presence of fractures. Here, we use radar observations on the Larsen C <span class="hlt">Ice</span> Shelf, Antarctica, to investigate (i) the termination of a 25 km long rift in the Churchill Peninsula suture <span class="hlt">zone</span>, which was found to contain ~60 m of accreted marine <span class="hlt">ice</span>, and (ii) the along-flow evolution of a suture <span class="hlt">zone</span> originating at Cole Peninsula. We determine a steady state field of basal melting/freezing rates and apply it to a flowline model to delineate the along-flow evolution of layers within the <span class="hlt">ice</span> shelf. The thickening surface wedge of locally accumulated meteoric <span class="hlt">ice</span>, which likely has limited lateral variation in its mechanical properties, accounts for ~60% of the total <span class="hlt">ice</span> thickness near the calving front. Thus, we infer that the lower ~40% of the <span class="hlt">ice</span> column and the material heterogeneities present there are responsible for resisting fracture propagation and thereby delaying tabular calving events, as demonstrated in the >40 year time series leading up to the 2004/2005 calving event for Larsen C. This likely represents a highly sensitive aspect of <span class="hlt">ice</span> shelf stability, as changes in the oceanic forcing may lead to the loss of this heterogeneity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23510081','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23510081"><span id="translatedtitle">Migration phenology and <span class="hlt">seasonal</span> fidelity of an Arctic marine predator in relation to sea <span class="hlt">ice</span> dynamics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cherry, Seth G; Derocher, Andrew E; Thiemann, Gregory W; Lunn, Nicholas J</p> <p>2013-07-01</p> <p>Understanding how <span class="hlt">seasonal</span> environmental conditions affect the timing and distribution of synchronized animal movement patterns is a central issue in animal ecology. Migration, a behavioural adaptation to <span class="hlt">seasonal</span> environmental fluctuations, is a fundamental part of the life history of numerous species. However, global climate change can alter the spatiotemporal distribution of resources and thus affect the <span class="hlt">seasonal</span> movement patterns of migratory animals. We examined sea <span class="hlt">ice</span> dynamics relative to migration patterns and <span class="hlt">seasonal</span> geographical fidelity of an Arctic marine predator, the polar bear (Ursus maritimus). Polar bear movement patterns were quantified using satellite-linked telemetry data collected from collars deployed between 1991-1997 and 2004-2009. We showed that specific sea <span class="hlt">ice</span> characteristics can predict the timing of <span class="hlt">seasonal</span> polar bear migration on and off terrestrial refugia. In addition, fidelity to specific onshore regions during the <span class="hlt">ice</span>-free period was predicted by the spatial pattern of sea <span class="hlt">ice</span> break-up but not by the timing of break-up. The timing of migration showed a trend towards earlier arrival of polar bears on shore and later departure from land, which has been driven by climate-induced declines in the availability of sea <span class="hlt">ice</span>. Changes to the timing of migration have resulted in polar bears spending progressively longer periods of time on land without access to sea <span class="hlt">ice</span> and their marine mammal prey. The links between increased atmospheric temperatures, sea <span class="hlt">ice</span> dynamics, and the migratory behaviour of an <span class="hlt">ice</span>-dependent species emphasizes the importance of quantifying and monitoring relationships between migratory wildlife and environmental cues that may be altered by climate change. PMID:23510081</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23510081','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23510081"><span id="translatedtitle">Migration phenology and <span class="hlt">seasonal</span> fidelity of an Arctic marine predator in relation to sea <span class="hlt">ice</span> dynamics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cherry, Seth G; Derocher, Andrew E; Thiemann, Gregory W; Lunn, Nicholas J</p> <p>2013-07-01</p> <p>Understanding how <span class="hlt">seasonal</span> environmental conditions affect the timing and distribution of synchronized animal movement patterns is a central issue in animal ecology. Migration, a behavioural adaptation to <span class="hlt">seasonal</span> environmental fluctuations, is a fundamental part of the life history of numerous species. However, global climate change can alter the spatiotemporal distribution of resources and thus affect the <span class="hlt">seasonal</span> movement patterns of migratory animals. We examined sea <span class="hlt">ice</span> dynamics relative to migration patterns and <span class="hlt">seasonal</span> geographical fidelity of an Arctic marine predator, the polar bear (Ursus maritimus). Polar bear movement patterns were quantified using satellite-linked telemetry data collected from collars deployed between 1991-1997 and 2004-2009. We showed that specific sea <span class="hlt">ice</span> characteristics can predict the timing of <span class="hlt">seasonal</span> polar bear migration on and off terrestrial refugia. In addition, fidelity to specific onshore regions during the <span class="hlt">ice</span>-free period was predicted by the spatial pattern of sea <span class="hlt">ice</span> break-up but not by the timing of break-up. The timing of migration showed a trend towards earlier arrival of polar bears on shore and later departure from land, which has been driven by climate-induced declines in the availability of sea <span class="hlt">ice</span>. Changes to the timing of migration have resulted in polar bears spending progressively longer periods of time on land without access to sea <span class="hlt">ice</span> and their marine mammal prey. The links between increased atmospheric temperatures, sea <span class="hlt">ice</span> dynamics, and the migratory behaviour of an <span class="hlt">ice</span>-dependent species emphasizes the importance of quantifying and monitoring relationships between migratory wildlife and environmental cues that may be altered by climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGC31B1044L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGC31B1044L"><span id="translatedtitle">Quantifying Uncertainties in the <span class="hlt">Seasonal</span> Cycle of Arctic Sea <span class="hlt">Ice</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lucas, D. D.; Covey, C. C.; Klein, R.; Tannahill, J.; Ivanova, D. P.</p> <p>2013-12-01</p> <p>Many climate models project that the Arctic Ocean will be free of summertime sea <span class="hlt">ice</span> within a century when forced with representative future greenhouse gas emission scenarios. To determine whether uncertainties in sea <span class="hlt">ice</span> physics can also lead to an <span class="hlt">ice</span>-free Arctic, we ran present-day ensemble simulations with the Community Climate System Model (CCSM4) that varied 7 parameters in the Community <span class="hlt">Ice</span> Code (CICE4) over expert-provided ranges. The September minimum in sea <span class="hlt">ice</span> extent computed by the ensemble ranges from 0.5 to 7.7 million km2, the lower end of which is significantly less than current observed values and lower than the models in the Coupled Model Intercomparison Project Phase 5 (CMIP5). CCSM4 can therefore simulate a summertime Arctic that is effectively free of sea <span class="hlt">ice</span> either by increasing greenhouse gas forcing or by keeping the forcing constant and varying CICE4 parameters within recommended ranges. We identified three key CICE4 parameters related to radiative and thermal properties of snow that drive this extreme ensemble variability. Given observational data, machine learning algorithms were also used to quantify and constrain probability distribution functions for these parameters, which can be sampled to provide probabilistic assessments of sea <span class="hlt">ice</span> characteristics simulated by CICE4. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was funded by the Uncertainty Quantification Strategic Initiative Laboratory Directed Research and Development Project at LLNL under project tracking code 10-SI-013 (UCRL LLNL-ABS-641752).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008AGUFM.C41B0504N&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008AGUFM.C41B0504N&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Seasonality</span> of Spectral Albedo and Transmission of Sea <span class="hlt">Ice</span> in the Transpolar Drift, Arctic Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nicolaus, M.; Gerland, S.; Hudson, S.; Haapala, J.; Hanson, S.; Palo, T.; Perovich, D. K.</p> <p>2008-12-01</p> <p>The physical and optical properties of snow and sea <span class="hlt">ice</span> in the Polar regions control the amount of solar short-wave radiation, reflected at the surface, scattered and absorbed within snow and <span class="hlt">ice</span>, and transmitted into the ocean beneath. Albedo and transmissivity of snow and sea <span class="hlt">ice</span> strongly influence heat fluxes within the coupled atmosphere-<span class="hlt">ice</span>-ocean system, and by that the evolution of the sea <span class="hlt">ice</span>. Spectral optical properties are crucial for primary production and evolution of sea <span class="hlt">ice</span> related microorganisms and various bio-chemical processes. Furthermore, the increasing importance of remote sensors when studying snow and sea <span class="hlt">ice</span>, raises the need for ground truth data of spectral optical and other physical properties of snow and sea <span class="hlt">ice</span>. Spectral albedo and transmission were measured continuously within high spectral and temporal resolution during the transpolar drift of the drifting schooner "Tara" through the Arctic Basin between 30 April and 05 September 2007. Simultaneous in-situ measurements of snow and sea <span class="hlt">ice</span> properties as well as a comprehensive meteorological program complement the dataset and allow common analysis and an integrated dataset. Results show significant <span class="hlt">seasonal</span> changes and highlight key events during the transitions from spring to summer and summer to autumn; including formation, evolution, and freeze up of melt ponds. We were able to derive absolute values of energy transfer through snow and <span class="hlt">ice</span> and into the upper ocean. The timing of changes in surface energy balance can be determined and characterized by including results from detailed snow and sea <span class="hlt">ice</span> studies as temperature and density profiles, snow stratigraphy, and sea <span class="hlt">ice</span> texture. Among others, they show that the melting period lasted 80 days which was about 20 days longer than on average. Interestingly, the observation period coincides with the time prior to the Arctic sea <span class="hlt">ice</span> extent minimum in autumn 2007. Consequently, the findings might assist to understand and explain processes</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016920','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016920"><span id="translatedtitle"><span class="hlt">Seasonal</span> changes in the spatial distribution of phytoplankton in small, temperate-<span class="hlt">zone</span> lakes</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Cloern, J.E.; Alpine, A.E.; Cole, B.E.; Heller, T.</p> <p>1992-01-01</p> <p>Sampling across two N Minnesota small lakes shows that phytoplankton patchiness is greatly enhanced during winter <span class="hlt">ice</span>-cover relative to the open-water <span class="hlt">seasons</span> of exposure to wind stress and rapid turbulent mixing. -Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C21A0312F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C21A0312F"><span id="translatedtitle">Using Airborne Lidar Data from <span class="hlt">Ice</span>Pod to Measure Annual and <span class="hlt">Seasonal</span> <span class="hlt">Ice</span> Changes Over Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frearson, N.; Bertinato, C.; Das, I.</p> <p>2014-12-01</p> <p>The <span class="hlt">Ice</span>Pod is a multi-sensor airborne science platform that supports a wide suite of instruments, including a Riegl VQ-580 infrared scanning laser, GPS-inertial positioning system, shallow and deep-<span class="hlt">ice</span> radars, visible-wave and infrared cameras, and upward-looking pyrometer. These instruments allow us to image the <span class="hlt">ice</span> from top to bottom, including the surface of melt-water plumes that originate at the <span class="hlt">ice</span>-ocean boundary. In collaboration with the New York Air National Guard 109th Airlift Wing, the <span class="hlt">Ice</span>Pod is flown on LC-130 aircraft, which presents the unique opportunity to routinely image the Greenland <span class="hlt">ice</span> sheet several times within a <span class="hlt">season</span>. This is particularly important for mass balance studies, as we can measure elevation changes during the melt <span class="hlt">season</span>. During the 2014 summer, laser data was collected via <span class="hlt">Ice</span>Pod over the Greenland <span class="hlt">ice</span> sheet, including Russell Glacier, Jakobshavn Glacier, Eqip Glacier, and Summit Camp. The Icepod will also be routinely operated in Antarctica. We present the initial testing, calibration, and error estimates from the first set of laser data that were collected on <span class="hlt">Ice</span>Pod. At a survey altitude of 1000 m, the laser swath covers ~ 1000 m. A Northrop-Grumman LN-200 tactical grade IMU is rigidly attached to the laser scanner to provide attitude data at a rate of 200 Hz. Several methods were used to determine the lever arm between the IMU center of navigation and GPS antenna phase center, terrestrial scanning laser, total station survey, and optimal estimation. Additionally, initial bore sight calibration flights yielded misalignment angles within an accuracy of ±4 cm. We also performed routine passes over the airport ramp in Kangerlussuaq, Greenland, comparing the airborne GPS and Lidar data to a reference GPS-based ground survey across the ramp, spot GPS points on the ramp and a nearby GPS base station. Positioning errors can severely impact the accuracy of a laser altimeter when flying over remote regions such as across the <span class="hlt">ice</span> sheets</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PolSc...2...41H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PolSc...2...41H"><span id="translatedtitle">Vertical material flux under <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> in the Okhotsk Sea north of Hokkaido, Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hiwatari, Takehiko; Shirasawa, Kunio; Fukamachi, Yasushi; Nagata, Ryuichi; Koizumi, Tomoyoshi; Koshikawa, Hiroshi; Kohata, Kunio</p> <p></p> <p>Downward material fluxes under <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> were measured using a time-series sediment trap installed at an offshore site in the Okhotsk Sea north of Hokkaido, Japan, from 13 January to 23 March 2005. The maximum fluxes of lithogenic material (753 mg m -2 day -1) and organic matter (mainly detritus; 333 mg m -2 day -1) were recorded during the period in which sea <span class="hlt">ice</span> drifted ashore and increased in extent, from 13 January to 9 February. Organic matter as fecal pellets (81-93 mg m -2 day -1) and opal as biosilica (51-67 mg m -2 day -1), representing diatom fluxes, were abundant in sediment trap samples obtained during the period of full sea <span class="hlt">ice</span> coverage from 10 February to 9 March. Microscopic observations revealed that fecal pellets were largely diatom frustules, suggesting that zooplankton actively grazed on <span class="hlt">ice</span> algae during the period of full sea <span class="hlt">ice</span> coverage. During the period of retreating sea <span class="hlt">ice</span>, from 10 to 23 March, the phytoplankton flux showed a rapid increase (from 9.5 to 22.5 × 10 6 cells m -2 day -1), reflecting their release into the water column as the sea <span class="hlt">ice</span> melted. Our results demonstrate that the quantity and quality of sinking biogenic and lithogenic materials vary with the <span class="hlt">seasonal</span> extent of sea <span class="hlt">ice</span> in mid-winter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980237537','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980237537"><span id="translatedtitle">Spatial Distribution of Trends and <span class="hlt">Seasonality</span> in the Hemispheric Sea <span class="hlt">Ice</span> Covers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gloersen, P.; Parkinson, C. L.; Cavalieri, D. J.; Cosmiso, J. C.; Zwally, H. J.</p> <p>1998-01-01</p> <p>We extend earlier analyses of a 9-year sea <span class="hlt">ice</span> data set that described the local <span class="hlt">seasonal</span> and trend variations in each of the hemispheric sea <span class="hlt">ice</span> covers to the recently merged 18.2-year sea <span class="hlt">ice</span> record from four satellite instruments. The <span class="hlt">seasonal</span> cycle characteristics remain essentially the same as for the shorter time series, but the local trends are markedly different, in some cases reversing sign. The sign reversal reflects the lack of a consistent long-term trend and could be the result of localized long-term oscillations in the hemispheric sea <span class="hlt">ice</span> covers. By combining the separate hemispheric sea <span class="hlt">ice</span> records into a global one, we have shown that there are statistically significant net decreases in the sea <span class="hlt">ice</span> coverage on a global scale. The change in the global sea <span class="hlt">ice</span> extent, is -0.01 +/- 0.003 x 10(exp 6) sq km per decade. The decrease in the areal coverage of the sea <span class="hlt">ice</span> is only slightly smaller, so that the difference in the two, the open water within the packs, has no statistically significant change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013QSRv...79...74C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013QSRv...79...74C&link_type=ABSTRACT"><span id="translatedtitle">Identification of contrasting <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> conditions during the Younger Dryas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cabedo-Sanz, Patricia; Belt, Simon T.; Knies, Jochen; Husum, Katrine</p> <p>2013-11-01</p> <p>A palaeo sea <span class="hlt">ice</span> reconstruction for northern Norway for the interval ca 13.8-7.2 cal ka BP has been performed using a combined organic geochemical proxy-based study of a marine sediment core (JM99-1200) obtained from Andfjorden (69° 15.95' N, 16° 25.09' E) and the outcomes compared with a series of other palaeoclimate studies carried out previously. Within this study, particular emphasis has been placed on the identification of the sea <span class="hlt">ice</span> conditions during the Younger Dryas and the application of different biomarker-based proxies to both identify and quantify <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> conditions. Firstly, the appearance of the specific sea <span class="hlt">ice</span> diatom proxy IP25 at ca 12.9 cal ka BP in the sedimentary record has provided an unambiguous but qualitative measure of <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> and thus the onset of the Younger Dryas stadial. The near continuous occurrence of IP25 for the next ca 1400 yr demonstrates <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> during this interval, although variable abundances suggest that the recurrent conditions in the early-mid Younger Dryas (ca 12.9-11.9 cal ka BP) changed significantly from stable to highly variable sea <span class="hlt">ice</span> conditions at ca 11.9 cal ka BP and this instability in sea <span class="hlt">ice</span> prevailed for the subsequent ca 400 yr, during which, an extremely short interval of permanent or near-permanent sea <span class="hlt">ice</span> was observed at ca 11.75 cal ka BP. At ca 11.5 cal ka BP, IP25 disappeared from the record indicating <span class="hlt">ice</span>-free conditions that signified the beginning of the Holocene. The IP25 concentrations were also combined with those of the open water phytoplankton biomarker brassicasterol to generate PBIP25 data from which more quantitative measurements of sea <span class="hlt">ice</span> were determined. PBIP25 data were consistent with, consecutively, <span class="hlt">seasonal</span> then infrequent sea <span class="hlt">ice</span> cover for the early-mid and late Younger Dryas, while further comparisons of the PBIP25 data with the outcomes of previous correlations with modelled sea <span class="hlt">ice</span> concentrations suggested that these intervals were characterised by ca</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://dx.doi.org/10.1175/1520-0442(2004)017<0067:DOTASI>2.0.CO;2','USGSPUBS'); return false;" href="http://dx.doi.org/10.1175/1520-0442(2004)017<0067:DOTASI>2.0.CO;2"><span id="translatedtitle">Duration of the Arctic sea <span class="hlt">ice</span> melt <span class="hlt">season</span>: Regional and interannual variability, 1979-2001</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Belchansky, G.I.; Douglas, D.C.; Platonov, N.G.</p> <p>2004-01-01</p> <p>Melt onset dates, freeze onset dates, and melt <span class="hlt">season</span> duration were estimated over Arctic sea <span class="hlt">ice</span>, 1979-2001, using passive microwave satellite imagery and surface air temperature data. Sea <span class="hlt">ice</span> melt duration for the entire Northern Hemisphere varied from a 104-day minimum in 1983 and 1996, to a 124-day maximum in 1989. Ranges in melt duration were highest in peripheral seas, numbering 32, 42, 44, and 51 days in the Laptev, Barents-Kara, East Siberian and Chukchi Seas, respectively. In the Arctic Ocean, average melt duration varied from a 75-day minimum in 1987 to a 103-day maximum in 1989. On average, melt onset in annual <span class="hlt">ice</span> began 10.6 days earlier than perennial <span class="hlt">ice</span>, and freeze onset in perennial <span class="hlt">ice</span> commenced 18.4 days earlier than annual <span class="hlt">ice</span>. Average annual melt dates, freeze dates, and melt durations in annual <span class="hlt">ice</span> were significantly correlated with <span class="hlt">seasonal</span> strength of the Arctic Oscillation (AO). Following high-index AO winters (January-March), spring melt tended to be earlier and autumn freeze later, leading to longer melt <span class="hlt">season</span> durations. The largest increases in melt duration were observed in the eastern Siberian Arctic, coincident with cyclonic low pressure and <span class="hlt">ice</span> motion anomalies associated with high-index AO phases. Following a positive AO shift in 1989, mean annual melt duration increased 2-3 weeks in the northern East Siberian and Chukchi Seas. Decreasing correlations between consecutive-year maps of melt onset in annual <span class="hlt">ice</span> during 1979-2001 indicated increasing spatial variability and unpredictability in melt distributions from one year to the next. Despite recent declines in the winter AO index, recent melt distributions did not show evidence of reestablishing spatial patterns similar to those observed during the 1979-88 low-index AO period. Recent freeze distributions have become increasingly similar to those observed during 1979-88, suggesting a recurrent spatial pattern of freeze chronology under low-index AO conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRC..120.7791S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRC..120.7791S"><span id="translatedtitle"><span class="hlt">Seasonal</span> and interannual variability of fast <span class="hlt">ice</span> extent in the southeastern Laptev Sea between 1999 and 2013</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Selyuzhenok, V.; Krumpen, T.; Mahoney, A.; Janout, M.; Gerdes, R.</p> <p>2015-12-01</p> <p>Along with changes in sea <span class="hlt">ice</span> extent, thickness, and drift speed, Arctic sea <span class="hlt">ice</span> regime is characterized by a decrease of fast <span class="hlt">ice</span> <span class="hlt">season</span> and reduction of fast <span class="hlt">ice</span> extent. The most extensive fast <span class="hlt">ice</span> cover in the Arctic develops in the southeastern Laptev Sea. Using weekly operational sea <span class="hlt">ice</span> charts produced by Arctic and Antarctic Research Institute (AARI, Russia) from 1999 to 2013, we identified five main key events that characterize the annual evolution of fast <span class="hlt">ice</span> in the southeastern Laptev Sea. Linking the occurrence of the key events with the atmospheric forcing, bathymetry, freezeup, and melt onset, we examined the processes driving annual fast <span class="hlt">ice</span> cycle. The analysis revealed that fast <span class="hlt">ice</span> in the region is sensitive to thermodynamic processes throughout a <span class="hlt">season</span>, while the wind has a strong influence only on the first stages of fast <span class="hlt">ice</span> development. The maximal fast <span class="hlt">ice</span> extent is closely linked to the bathymetry and local topography and is primarily defined by the location of shoals, where fast <span class="hlt">ice</span> is likely grounded. The annual fast <span class="hlt">ice</span> cycle shows significant changes over the period of investigation, with tendencies toward later fast <span class="hlt">ice</span> formation and earlier breakup. These tendencies result in an overall decrease of the fast <span class="hlt">ice</span> <span class="hlt">season</span> by 2.8 d/yr, which is significantly higher than previously reported trends.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015TCD.....9.5521K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015TCD.....9.5521K&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Seasonal</span> sea <span class="hlt">ice</span> predictions for the Arctic based on assimilation of remotely sensed observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kauker, F.; Kaminski, T.; Ricker, R.; Toudal-Pedersen, L.; Dybkjaer, G.; Melsheimer, C.; Eastwood, S.; Sumata, H.; Karcher, M.; Gerdes, R.</p> <p>2015-10-01</p> <p>The recent thinning and shrinking of the Arctic sea <span class="hlt">ice</span> cover has increased the interest in <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> forecasts. Typical tools for such forecasts are numerical models of the coupled ocean sea <span class="hlt">ice</span> system such as the North Atlantic/Arctic Ocean Sea <span class="hlt">Ice</span> Model (NAOSIM). The model uses as input the initial state of the system and the atmospheric boundary condition over the forecasting period. This study investigates the potential of remotely sensed <span class="hlt">ice</span> thickness observations in constraining the initial model state. For this purpose it employs a variational assimilation system around NAOSIM and the Alfred Wegener Institute's CryoSat-2 <span class="hlt">ice</span> thickness product in conjunction with the University of Bremen's snow depth product and the OSI SAF <span class="hlt">ice</span> concentration and sea surface temperature products. We investigate the skill of predictions of the summer <span class="hlt">ice</span> conditions starting in March for three different years. Straightforward assimilation of the above combination of data streams results in slight improvements over some regions (especially in the Beaufort Sea) but degrades the over-all fit to independent observations. A considerable enhancement of forecast skill is demonstrated for a bias correction scheme for the CryoSat-2 <span class="hlt">ice</span> thickness product that uses a spatially varying scaling factor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMGC51F1081J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMGC51F1081J"><span id="translatedtitle">Modeling <span class="hlt">seasonality</span> of <span class="hlt">ice</span> and ocean carbon production in the Arctic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jin, M.; Deal, C. M.; Ji, R.</p> <p>2011-12-01</p> <p>In the Arctic Ocean, both phytoplankton and sea <span class="hlt">ice</span> algae are important contributors to the primary production and the arctic food web. Copepod in the arctic regions have developed their feeding habit depending on the timing between the <span class="hlt">ice</span> algal bloom and the subsequent phytoplankton bloom. A mismatch of the timing due to climate changes could have dramatic consequences on the food web as shown by some regional observations. In this study, a global coupled <span class="hlt">ice</span>-ocean-ecosystem model was used to assess the <span class="hlt">seasonality</span> of the <span class="hlt">ice</span> algal and phytoplankton blooms in the arctic. The <span class="hlt">ice</span>-ocean ecosystem modules are fully coupled in the physical model POP-CICE (Parallel Ocean Program- Los Alamos Sea <span class="hlt">Ice</span> Model). The model results are compared with various observations. The modeled <span class="hlt">ice</span> and ocean carbon production were analyzed by regions and their linkage to the physical environment changes (such as changes of <span class="hlt">ice</span> concentration and water temperature, and light intensity etc.) between low- and high-<span class="hlt">ice</span> years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984JGR....89.2087C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984JGR....89.2087C"><span id="translatedtitle">Sea <span class="hlt">ice</span> structure and biological activity in the Antarctic marginal <span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clarke, D. B.; Ackley, S. F.</p> <p>1984-03-01</p> <p><span class="hlt">Ice</span> cores obtained during October-November 1981 from Weddell Sea pack <span class="hlt">ice</span> were analyzed for physical, chemical, and biological parameters. Frazil <span class="hlt">ice</span>, which is associated with dynamic, turbulent conditions in the water column, predominated (70%). Both floe thickness and salinity indicate <span class="hlt">ice</span> which is less than 1 year old. Chemical analyses, particularly with regard to the nutrients, revealed a complex picture. Phosphate values are scattered relative to the dilution curve. Nitrate and silicate values are lower than expected from simple scaling with salinity and suggest diatom growth within the <span class="hlt">ice</span>. Nitrite values are higher in the <span class="hlt">ice</span> than in adjacent waters. Frazil <span class="hlt">ice</span> formation which probably concentrates algal cells from the water column into <span class="hlt">ice</span> floes results in higher initial chlorophyll a concentrations in the <span class="hlt">ice</span> than in adjacent waters. This mechanical concentration is further enhanced by subsequent reproduction within the <span class="hlt">ice</span>. <span class="hlt">Ice</span> core chlorophyll ranged from 0.09 to 3.8 mg/m3, comparable to values previously reported for this area but significantly lower than values for Antarctic coastal fast <span class="hlt">ice</span>. The dominance of frazil <span class="hlt">ice</span> in the Weddell is one of the major differences between this area and others. Consequently, we believe that <span class="hlt">ice</span> structural conditions significantly influence the biological communities in the <span class="hlt">ice</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A33M0387Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A33M0387Y"><span id="translatedtitle">An Evaluation of the <span class="hlt">Seasonal</span> Arctic Sea <span class="hlt">Ice</span> Predictions from CFSv2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Q.; Wang, M.; Overland, J. E.</p> <p>2015-12-01</p> <p>The rapid reductions in Arctic sea <span class="hlt">ice</span> have been observed in the past several decades, especially at the end of the summer melt <span class="hlt">season</span> in September. It is necessary to have a reliable <span class="hlt">seasonal</span> forecast of Arctic sea <span class="hlt">ice</span>. In this study, we examined the Arctic sea <span class="hlt">ice</span> predictions produced by NCEP Climate Forecast System version 2 (CFSv2) in the real- time operational mode. Forecasts were initialized monthly for two-year period (March 2014 to September 2015). Forecasts of sea <span class="hlt">ice</span> extent (SIE) and concentration (SIC) were evaluated against the sea <span class="hlt">ice</span> analysis (HadISST_<span class="hlt">ice</span>) from the Hadley Center. We found that the Arctic September SIE forecasts from CFS were overestimated with the biases in SIC mainly originated from the Beaufort Sea, Laptev Sea and Fram Strait. For 2014, we found that the forecast initialized from March with the lead-time of 6 months gave the best September SIE forecast while the forecast initialized from July with the lead-time of 2 months had the worst September SIE forecast. In order to understand the forecast biases in September sea <span class="hlt">ice</span>, the atmospheric forecasted forcings including incoming solar/Infrared radiation, upward solar/infrared radiation from surface, latent and sensible heat flux, 2-meter air temperature, cloud fraction, sea level pressure and 10-meter wind from CFSv2 were evaluated using the European Center for Medium-Range Weather Forecasts Interim Re-Analysis (ERA-Interim) .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMOS14A..04Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMOS14A..04Z"><span id="translatedtitle">Local Effects of <span class="hlt">Ice</span> Floes on Skin Sea Surface Temperature in the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> from UAVs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zappa, C. J.; Brown, S.; Emery, W. J.; Adler, J.; Wick, G. A.; Steele, M.; Palo, S. E.; Walker, G.; Maslanik, J. A.</p> <p>2013-12-01</p> <p>Recent years have seen extreme changes in the Arctic. Particularly striking are changes within the Pacific sector of the Arctic Ocean, and especially in the seas north of the Alaskan coast. These areas have experienced record warming, reduced sea <span class="hlt">ice</span> extent, and loss of <span class="hlt">ice</span> in areas that had been <span class="hlt">ice</span>-covered throughout human memory. Even the oldest and thickest <span class="hlt">ice</span> types have failed to survive through the summer melt period in areas such as the Beaufort Sea and Canada Basin, and fundamental changes in ocean conditions such as earlier phytoplankton blooms may be underway. Marginal <span class="hlt">ice</span> <span class="hlt">zones</span> (MIZ), or areas where the "<span class="hlt">ice</span>-albedo feedback" driven by solar warming is highest and <span class="hlt">ice</span> melt is extensive, may provide insights into the extent of these changes. Airborne remote sensing, in particular InfraRed (IR), offers a unique opportunity to observe physical processes at sea-<span class="hlt">ice</span> margins. It permits monitoring the <span class="hlt">ice</span> extent and coverage, as well as the <span class="hlt">ice</span> and ocean temperature variability. It can also be used for derivation of surface flow field allowing investigation of turbulence and mixing at the <span class="hlt">ice</span>-ocean interface. Here, we present measurements of visible and IR imagery of melting <span class="hlt">ice</span> floes in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> north of Oliktok Point AK in the Beaufort Sea made during the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> Ocean and <span class="hlt">Ice</span> Observations and Processes EXperiment (MIZOPEX) in July-August 2013. The visible and IR imagery were taken from the unmanned airborne vehicle (UAV) ScanEagle. The visible imagery clearly defines the scale of the <span class="hlt">ice</span> floes. The IR imagery show distinct cooling of the skin sea surface temperature (SST) as well as a intricate circulation and mixing pattern that depends on the surface current, wind speed, and near-surface vertical temperature/salinity structure. Individual <span class="hlt">ice</span> floes develop turbulent wakes as they drift and cause transient mixing of an influx of colder surface (fresh) melt water. The upstream side of the <span class="hlt">ice</span> floe shows the coldest skin SST, and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813447B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813447B"><span id="translatedtitle">Observational uncertainty of Arctic sea-<span class="hlt">ice</span> concentration significantly affects <span class="hlt">seasonal</span> climate forecasts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bunzel, Felix; Notz, Dirk; Baehr, Johanna; Müller, Wolfgang; Fröhlich, Kristina</p> <p>2016-04-01</p> <p>We examine how the choice of a particular satellite-retrieved sea-<span class="hlt">ice</span> concentration dataset used for initialising <span class="hlt">seasonal</span> climate forecasts impacts the prediction skill of Arctic sea-<span class="hlt">ice</span> area and Northern hemispheric 2-meter air temperatures. To do so, we performed two assimilation runs with the Max Planck Institute Earth System Model (MPI-ESM) from 1979 to 2012, where atmospheric and oceanic parameters as well as sea-<span class="hlt">ice</span> concentration were assimilated using Newtonian relaxation. The two assimilation runs differ only in the sea-<span class="hlt">ice</span> concentration dataset used for assimilating sea <span class="hlt">ice</span>. In the first run, we use sea-<span class="hlt">ice</span> concentrations as derived by the NASA-Team algorithm, while in the second run we use sea-<span class="hlt">ice</span> concentrations as derived from the Bootstrap algorithm. A major difference between these two sea-<span class="hlt">ice</span> concentration data products involves the treatment of melt ponds. While for both products melt ponds appear as open water in the raw satellite data, the Bootstrap algorithm more strongly attempts to offset this systematic bias by synthetically increasing the retrieved <span class="hlt">ice</span> concentration during summer months. For each year of the two assimilation runs we performed a 10-member ensemble of hindcast experiments starting on 1 May and 1 November with a hindcast length of 6 months. For hindcasts started in November, initial differences in Arctic sea-<span class="hlt">ice</span> area and surface temperature decrease rapidly throughout the freezing period. For hindcasts started in May, initial sea-<span class="hlt">ice</span> area differences increase over time. By the end of the melting period, this causes significant differences in 2-meter air temperature of regionally more than 3°C. Hindcast skill for surface temperatures over Europe and North America is higher with Bootstrap initialization during summer and with NASA Team initialisation during winter. This implies that the choice of the sea-<span class="hlt">ice</span> data product and, thus, the observational uncertainty also affects forecasts of teleconnections that depend on Northern</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/1013155','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/1013155"><span id="translatedtitle"><span class="hlt">Seasonal</span> comparisons of sea <span class="hlt">ice</span> concentration estimates derived from SSM/I, OKEAN and RADARSAT data</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Belchansky, G.I.; Douglas, D.C.</p> <p>2002-01-01</p> <p>The SSM/I microwave satellite radiometer and its predecessor SMMR are primary sources of information for global sea-<span class="hlt">ice</span> and climate studies. However, comparisons of SSM/I, LANDSAT, AVHRR and ERS-1 SAR have shown substantial <span class="hlt">seasonal</span> and regional differences in their estimates of sea <span class="hlt">ice</span> concentration. To evaluate these differences, we compared SSM/I estimates of sea <span class="hlt">ice</span> coverage derived with the NASA Team and Bootstrap algorithms to estimates made using RADARSAT, and OKEAN-01 satellite sensor data. The study area included the Barents, Kara Sea, Laptev Sea, and adjacent parts of the Arctic Ocean, during October 1995 through October 1999. <span class="hlt">Ice</span> concentration estimates from spatially and temporally near-coincident imagery were calculated using independent algorithms for each sensor type. The OKEAN algorithm implemented the satellite's two-channel active (radar) and passive microwave data in a linear mixture model based on the measured values of brightness temperature and radar backscatter. The RADARSAT algorithm utilized a segmentation approach of the measured radar backscatter, and the SSM/I <span class="hlt">ice</span> concentrations were derived at National Snow and <span class="hlt">Ice</span> Data Center (NSIDC) using the NASA Team and Bootstrap algorithms. <span class="hlt">Seasonal</span> and monthly differences between SSM/I, OKEAN, and RADARSAT <span class="hlt">ice</span> concentrations were calculated and compared. Overall, total sea <span class="hlt">ice</span> concentration estimates derived independently from near-coincident RADARSAT, OKEAN-01 and SSM/I satellite imagery demonstrated mean differences of less than 5.5 % (SD < 9.5%) during the winter period. Differences between the SSM/I NASA Team and the SSM/I Bootstrap concentrations were no more than 3.1 % (SD < 5.4%) during this period. RADARSAT and OKEAN-01 data both yielded higher total <span class="hlt">ice</span> concentrations than the NASA Team and the Bootstrap algorithms. The Bootstrap algorithm yielded higher total <span class="hlt">ice</span> concentrations than the NASA Team algorithm. Total <span class="hlt">ice</span> concentrations derived from OKEAN-01 and SSM/I satellite imagery were</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1815197K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1815197K"><span id="translatedtitle">Skill improvement of <span class="hlt">seasonal</span> Arctic sea <span class="hlt">ice</span> forecasts using bias-correction and ensemble calibration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krikken, Folmer; Hazeleger, Wilco; Vlot, Willem; Schmeits, Maurice; Guemas, Virginie</p> <p>2016-04-01</p> <p>We explore the standard error and skill of dynamical <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> forecasts of the Arctic using different bias-correction and ensemble calibration methods. The latter is often used in weather forecasting, but so far has not been applied to Arctic sea <span class="hlt">ice</span> forecasts. We use <span class="hlt">seasonal</span> predictions of Arctic sea <span class="hlt">ice</span> of a 5-member ensemble forecast using the fully coupled GCM EC-Earth, with model initial states obtained by nudging towards ORAS4 and ERA-Interim. The raw model forecasts contain large biases in total sea <span class="hlt">ice</span> area, especially during the summer months. This is mainly caused by a difference in average <span class="hlt">seasonal</span> cycle between EC-Earth and observations, which translates directly into the forecasts yielding large biases. Further errors are introduced by the differences in long term trend between the observed sea <span class="hlt">ice</span>, and the uninitialised EC-earth simulation. We find that extended logistic regression (ELR) and heteroscedastic extended logistic regression (HELR) both prove viable ensemble calibration methods, and improve the forecasts substantially compared to standard bias correction techniques. No clear distinction between ELR and HELR is found. Forecasts starting in May have higher skill (CRPSS > 0 up to 5 months lead time) than forecasts starting in August (2-3 months) and November (2-3 months), with trend-corrected climatology as reference. Analysis of regional skill in the Arctic shows distinct differences, where mainly the Arctic ocean and the Kara and Barents sea prove to be one of the more predictable regions with skilful forecasts starting in May up to 5-6 months lead time. Again, forecasts starting in August and November show much lower regional skill. Overall, it is still difficult to beat relative simple statistical forecasts, but by using ELR and HELR we are getting reasonably close to skilful <span class="hlt">seasonal</span> forecasts up to 12 months lead time. These results show there is large potential, and need, for using ensemble calibration in <span class="hlt">seasonal</span> forecasts of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991JMS.....2..131G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991JMS.....2..131G"><span id="translatedtitle">Austral winter distributions of large tintinnid and large sarcodinid protozooplankton in the <span class="hlt">ice</span>-edge <span class="hlt">zone</span> of the Weddell/Scotia Seas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gowing, Marcia M.; Garrison, David L.</p> <p>1991-07-01</p> <p><span class="hlt">Seasonal</span> distribution and abundance data for large sarcodinid protozooplankton (Radiolaria, Foraminifera, Acantharia and the heliozoan Sticholonche spp.) and larger tintinnid ciliates (e.g., Laackmaniella spp.) are necessary for evaluating their roles in food webs and particle fluxes. As part of the Antarctic Marine Ecosystem Research in the <span class="hlt">Ice</span> Edge <span class="hlt">Zone</span> (AMERIEZ) project, we sampled these large (≥ 50 μm) protozooplankton in the winter <span class="hlt">ice</span> edge <span class="hlt">zone</span> of the Scotia/Weddell Seas. Organisms alive at the time of capture were counted in large volume (60 1) water samples from 5 paired depths in the upper 210 m from 17 stations. Relationships between abundances and environmental factors in <span class="hlt">ice</span>-covered, <span class="hlt">ice</span> edge, and open waters were assessed with correlation, cluster, and multidimensional scaling analyses. Mean abundances of large tintinnids were less than 3150 per m 3, and mean abundances of the individual sarcodine groups were generally less than 1000 per m 3. The most pronounced distributional patterns were related to depth. In general, large tintinnids were more abundant in the colder waters from 0-85 m, a <span class="hlt">zone</span> encompassed by the mixed layer and the euphotic <span class="hlt">zone</span>. Acantharians were more abundant in this upper <span class="hlt">zone</span> only in <span class="hlt">ice</span>-covered waters. Radiolaria (predominantly phaeodarians) and the heliozoan Sticholonche spp. were more abundant from 115 to 210 m, a <span class="hlt">zone</span> of warmer, more saline water. Foraminiferan distributions showed little pattern with depth. Results of the cluster analyses also suggested that depth was the most significant effect determining similarity among assemblages of large protozooplankton at the 17 stations. The few correlations between abundances of the groups and chlorophyll a probably reflect relationships more complex than grazing. Abundances of large tintinnids were higher in surface waters under the <span class="hlt">ice</span> than at the <span class="hlt">ice</span> edge or in open water. This could result from their feeding on algal cells released from the base of the <span class="hlt">ice</span> or it may be a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title36-vol1/pdf/CFR-2011-title36-vol1-sec13-912.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title36-vol1/pdf/CFR-2011-title36-vol1-sec13-912.pdf"><span id="translatedtitle">36 CFR 13.912 - Kantishna area summer <span class="hlt">season</span> firearm safety <span class="hlt">zone</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>..., unless they are defending life or property. (a) The summer <span class="hlt">season</span> begins on the Saturday of Memorial Day... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Kantishna area summer <span class="hlt">season</span>... Preserve General Provisions § 13.912 Kantishna area summer <span class="hlt">season</span> firearm safety <span class="hlt">zone</span>. What is...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title36-vol1/pdf/CFR-2014-title36-vol1-sec13-912.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title36-vol1/pdf/CFR-2014-title36-vol1-sec13-912.pdf"><span id="translatedtitle">36 CFR 13.912 - Kantishna area summer <span class="hlt">season</span> firearm safety <span class="hlt">zone</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>..., unless they are defending life or property. (a) The summer <span class="hlt">season</span> begins on the Saturday of Memorial Day... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Kantishna area summer <span class="hlt">season</span>... Preserve General Provisions § 13.912 Kantishna area summer <span class="hlt">season</span> firearm safety <span class="hlt">zone</span>. What is...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title36-vol1/pdf/CFR-2012-title36-vol1-sec13-912.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title36-vol1/pdf/CFR-2012-title36-vol1-sec13-912.pdf"><span id="translatedtitle">36 CFR 13.912 - Kantishna area summer <span class="hlt">season</span> firearm safety <span class="hlt">zone</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>..., unless they are defending life or property. (a) The summer <span class="hlt">season</span> begins on the Saturday of Memorial Day... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Kantishna area summer <span class="hlt">season</span>... Preserve General Provisions § 13.912 Kantishna area summer <span class="hlt">season</span> firearm safety <span class="hlt">zone</span>. What is...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DSRII.131...75J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DSRII.131...75J"><span id="translatedtitle">Thermodynamics of slush and snow-<span class="hlt">ice</span> formation in the Antarctic sea-<span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jutras, Mathilde; Vancoppenolle, Martin; Lourenço, Antonio; Vivier, Frédéric; Carnat, Gauthier; Madec, Gurvan; Rousset, Clément; Tison, Jean-Louis</p> <p>2016-09-01</p> <p>Snow over Antarctic sea <span class="hlt">ice</span> is often flooded by brine or seawater, particularly in spring, forming slush and snow <span class="hlt">ice</span>. Here, we evaluate the representation of the thermodynamics of slush and snow-<span class="hlt">ice</span> formation in large-scale sea-<span class="hlt">ice</span> models, using laboratory experiments (NaCl solutions poured into grated <span class="hlt">ice</span> in an isolated container). Scaling analysis highlights latent heat as the main term of the energy budget. The temperature of the new sea <span class="hlt">ice</span> immediately after flooding is found very close to the saltwater freezing point, whereas its bulk salinity is typically > 20 g / kg. Large-scale sea-<span class="hlt">ice</span> models faithfully represent such physics, yet the uncertainty on the origin of flooding saltwater impacts the calculated new <span class="hlt">ice</span> temperature, because of the different salinities of seawater and brine. The laboratory experiments also suggest a potential limitation to the existing physical representations of flooding: for brine fractions > 60 %, <span class="hlt">ice</span> crystals start floating upon saltwater. Natural sea-<span class="hlt">ice</span> observations suggest that the isolated system assumption holds for a few hours at most, after which rapid heat and salt exchanges mostly destroy the initial flooding signature on temperature and salinity. A small footprint on <span class="hlt">ice</span> salinity remains however, natural snow <span class="hlt">ice</span> is found 3-5 g/kg more saline than other forms of sea <span class="hlt">ice</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoRL..41.5208M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoRL..41.5208M"><span id="translatedtitle">Importance of initial conditions in <span class="hlt">seasonal</span> predictions of Arctic sea <span class="hlt">ice</span> extent</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Msadek, R.; Vecchi, G. A.; Winton, M.; Gudgel, R. G.</p> <p>2014-07-01</p> <p>We present <span class="hlt">seasonal</span> predictions of Arctic sea <span class="hlt">ice</span> extent (SIE) over the 1982-2013 period using two suites of retrospective forecasts initialized from a fully coupled ocean-atmosphere-sea <span class="hlt">ice</span> assimilation system. High skill scores are found in predicting year-to-year fluctuations of Arctic SIE, with significant correlations up to 7 month ahead for September detrended anomalies. Predictions over the recent era, which coincides with an improved observational coverage, outperform the earlier period for most target months. We find, however, a degradation of skill in September during the last decade, a period of sea <span class="hlt">ice</span> thinning in observations. The two prediction models, Climate Model version 2.1 (CM2.1) and Forecast-oriented Low Ocean Resolution (FLOR), share very similar ocean and <span class="hlt">ice</span> component and initialization but differ by their atmospheric component. FLOR has improved climatological atmospheric circulation and sea <span class="hlt">ice</span> mean state, but its skill is overall similar to CM2.1 for most <span class="hlt">seasons</span>, which suggests a key role for initial conditions in predicting <span class="hlt">seasonal</span> SIE fluctuations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C41E..07N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C41E..07N"><span id="translatedtitle">Rapid growth and <span class="hlt">seasonal</span> persistence of efficient subglacial drainage under kilometre thick Greenland <span class="hlt">ice</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nienow, P.; Wadham, J.; Chandler, D.; Doyle, S. H.; Tedstone, A. J.; Hubbard, A., II</p> <p>2015-12-01</p> <p>The relationship between surface melt and <span class="hlt">ice</span> motion partly determines the sensitivity of the Greenland <span class="hlt">Ice</span> Sheet to climate, and the structure of the subglacial drainage system may be critical in controlling how changing melt-rates will impact on future <span class="hlt">ice</span> dynamics. However, the extent to which efficient subglacial drainage develops tens of km inland from the <span class="hlt">ice</span> margin under thick (>1km) <span class="hlt">ice</span> remains equivocal. In particular, several numerical modelling studies suggest that under such conditions subglacial channels cannot evolve on <span class="hlt">seasonal</span> timescales, even under extreme inputs of surface meltwater. Here, we present hydrological and <span class="hlt">ice</span>-motion data collected in summer 2012 in the vicinity of a moulin located ~40 km from the western margin of the Greenland <span class="hlt">Ice</span> Sheet, where <span class="hlt">ice</span> is ~1km thick. Supraglacial discharge into the moulin was monitored from the onset of surface drainage and the tracer sulphur hexafluoride (SF6) was injected into the moulin at repeat intervals and its emergence was monitored at its proglacial river outlet. The tracer results indicate rapid evolution from a slow, inefficient drainage system to a fast, hydraulically efficient system within ~three weeks from the onset of surface drainage. Once an efficient hydrological pathway was established, it remained open - as evidenced by the fast tracer return times - even during periods of low surface melt (~0.01m/d), when discharge into the moulin was <4 m3 s-1 and ceased overnight. <span class="hlt">Ice</span> motion in the vicinity of the moulin slowed following the establishment of the efficient drainage pathway with a clear diurnal cyclicity driven by variations in supraglacial discharge. Our results confirm that hydraulically-efficient subglacial drainage can exist 10s km from the <span class="hlt">ice</span> sheet margin where <span class="hlt">ice</span> is ~1km thick, that the drainage configuration can form in a matter of weeks, and that it persists even during cool periods when local surface melt rates and inputs are low.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.C51A0542R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.C51A0542R"><span id="translatedtitle">The Increase of the <span class="hlt">Ice</span>-free <span class="hlt">Season</span> as Further Indication of the Rapid Decline of the Arctic sea <span class="hlt">ice</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodrigues, J.</p> <p>2008-12-01</p> <p>The unprecedented depletion of sea <span class="hlt">ice</span> in large sectors of the Arctic Ocean in the summer of 2007 has been the subject of many publications which highlight the spectacular disappearance of the sea <span class="hlt">ice</span> at the time of minimum <span class="hlt">ice</span> cover or emphasise the losses at very high latitudes. However, minimum values can be strongly affected by specific circumstances occurring in a comparatively short time interval. The unusually clear skies and the presence of a particular wind pattern over the Arctic Ocean may partly explain the record minimum attained in September 2007. In this contribution, instead of limiting ourselves to the September minimum or the March maximum, we consider the <span class="hlt">ice</span> conditions throughout the year, opting for a less used, and hopefully more convenient approach. We chose as variables to describe the evolution of the sea <span class="hlt">ice</span> situation in the Arctic Ocean and peripheral seas in the 1979-2007 period the length of the <span class="hlt">ice</span>- free <span class="hlt">season</span> (LIFS) and the inverse sea <span class="hlt">ice</span> index (ISII). The latter is a quantity that measures the degree of absence of sea <span class="hlt">ice</span> in a year and varies between zero (when there is a perennial <span class="hlt">ice</span> cover) and one (when there is open water all year round). We used sea <span class="hlt">ice</span> concentration data obtained from passive microwave satellite imagery and processed with the Bootstrap algorithm for the SMMR and SSM/I periods, and with the Enhanced NASA Team algorithm for the AMSR-E period. From a linear fit of the observed data, we found that the average LIFS in the Arctic went from 118 days in the late 1970s to 148 days in 2006, which represents an average rate of increase of 1.1 days/year. In the period 2001-2007 the LIFS increased monotonically at an average rate of 5.5 days/year, in good agreement with the general consensus that the Arctic sea <span class="hlt">ice</span> is currently in an accelerated decline. We also found that 2007 was the longest <span class="hlt">ice</span>- free <span class="hlt">season</span> on record (168 days). The ISII also reached a maximum in 2007 . We also investigated what happened at the regional</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900025623&hterms=Arctic+Sea&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DArctic%2BSea','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900025623&hterms=Arctic+Sea&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DArctic%2BSea"><span id="translatedtitle">Arctic sea <span class="hlt">ice</span> 1973-1987 - <span class="hlt">Seasonal</span>, regional, and interannual variability</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parkinson, Claire L.; Cavalieri, Donald J.</p> <p>1989-01-01</p> <p>The <span class="hlt">seasonal</span>, regional, and interannual variations in the Northern-Hemisphere sea-<span class="hlt">ice</span> cover were investigated for the time period 1973-1987, using data derived from the Nimbus-5 ESMR and the Nimbus-7 SMMR. The records show an average <span class="hlt">seasonal</span> cycle of sea-<span class="hlt">ice</span> cover, ranging from a summer minimum of 8.5 x 10 to the 6th sq km in September to a winter maximum of 15 x 10 to the 6th sq km in March, with considerable interannual variability found both regionally and hemispherically. Some regions (e.g., the Baffin Bay/Davis Strait, were found to exhibit upward trends in sea-<span class="hlt">ice</span> extents, while other regions (e.g., the Kara Sea and the Barents Sea) exhibited downward trend. However, the record for the Northern Hemisphere overall showed no significant trend over the 1973-1987 period, giving no evidence of consistent warming or cooling of the north polar region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.C43E0602P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.C43E0602P"><span id="translatedtitle">Sea <span class="hlt">Ice</span> Drift in the Arctic Ocean. <span class="hlt">Seasonal</span> Variability and Long-Term Changes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pavlov, V.; Pavlova, O.</p> <p>2010-12-01</p> <p>Variability in the drift of sea <span class="hlt">ice</span> in the Arctic Ocean is an important parameter that can be used to characterise the thermodynamic processes in the Arctic. Knowledge of the features of sea <span class="hlt">ice</span> drift in the Arctic Ocean is necessary for climate research, for an improved understanding of polar ecology and as an aid to human activity in the Arctic Ocean. Monthly mean sea <span class="hlt">ice</span> drift velocities, computed from Advanced Very High Resolution Radiometer (AVHRR), Scanning Multichannel Microwave Radiometer (SMMR), Special Sensor Microwave/Imager (SSM/I), and International Arctic Buoy Programme (IABP) buoy data, are used to investigate the spatial and temporal variability of <span class="hlt">ice</span> motion in the Arctic Ocean and Nordic Seas from 1979. Sea <span class="hlt">ice</span> drift in the Arctic Ocean is characterized by strong <span class="hlt">seasonal</span> and inter-annual variability. The results of combined statistical analysis of sea <span class="hlt">ice</span> velocities and wind fields over the Arctic Ocean suggest that the <span class="hlt">seasonal</span> changes of local wind are a predominant factor in the formation of the sea <span class="hlt">ice</span> velocities annual cycle. Sea <span class="hlt">ice</span> drift velocities mirror <span class="hlt">seasonal</span> changes of the wind in the Arctic, reaching a maximum in December, with a minimum in June. In the central part of the Arctic Ocean and in the area near the Canadian shore the amplitude of this variation is not more than 2 cm/ sec. The maximum amplitudes are found in the Fram Strait (9-10 cm/sec), Beaufort Gyre (6-7 cm/sec) and the northern part of Barents Sea (5-6 cm/sec). Low frequency variations of sea <span class="hlt">ice</span> drift velocities, with periods of 2.0-2.5 yrs and 5.0-6.0 yrs, are related to reorganization of the atmospheric circulation over the Arctic. There is evidence that the average sea <span class="hlt">ice</span> velocity for the whole of the Arctic Ocean is increasing, with a positive trend for the period of last three decades. Trends of the monthly mean <span class="hlt">ice</span> drift velocities are positive almost everywhere in the Arctic Ocean. In the Baffin Bay, Fram Strait and Barents Sea regions, sea <span class="hlt">ice</span> velocities</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988JGR....9312449C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988JGR....9312449C"><span id="translatedtitle">Numerical simulations of the profile properties of undeformed first-year sea <span class="hlt">ice</span> during the growth <span class="hlt">season</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cox, G. F. N.; Weeks, W. F.</p> <p>1988-10-01</p> <p>A simulation scheme is developed that estimates salinity profiles for first-year sea <span class="hlt">ice</span> during the growth <span class="hlt">season</span> as a function of the growth history of the <span class="hlt">ice</span>. The model considers the dependence of the initial <span class="hlt">ice</span> salinity on <span class="hlt">ice</span> growth velocity and sea water salinity and also the subsequent drainage of brine from the <span class="hlt">ice</span>. The equation for <span class="hlt">ice</span> growth assumes a linear temperature profile within the <span class="hlt">ice</span> and is driven by surface heat balance equations that are based on smoothed climatic data for the central Arctic Basin. The estimated salinity profiles are in good agreement with natural profiles. Although temperature and salinity profiles depend upon the time of the year when <span class="hlt">ice</span> growth is initiated, the brine volume profiles which they specify are essentially a unique function of <span class="hlt">ice</span> thickness; a conclusion that holds even when the insulative effects of snow are considered. The temperature and brine volume profiles are then utilized to calculate the <span class="hlt">ice</span> strength and elastic modulus profiles, which in turn specify the composite mechanical properties of the <span class="hlt">ice</span> sheets through the application of a theory developed by Assur (1967). Significant differences, which are largest for thin <span class="hlt">ice</span> sheets, are observed between <span class="hlt">ice</span> sheet properties as calculated using composite plate theory and properties calculated from uniform plate theory and average <span class="hlt">ice</span> properties. These results provide a justification for the practice, common within the <span class="hlt">ice</span> modeling community, of parameterizing the mechanical behavior of pack <span class="hlt">ice</span> on the basis of the <span class="hlt">ice</span> thickness distribution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.G21A0801Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.G21A0801Y"><span id="translatedtitle">Investigation of <span class="hlt">seasonal</span> melting of Greenland using GPS records reveals significant <span class="hlt">ice</span> mass loss in 2010</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Q.; Dixon, T.; Wdowinski, S.</p> <p>2011-12-01</p> <p>Greenland has experienced significant <span class="hlt">ice</span> mass loss in the past decade. High-precision global positioning system (GPS) data from sites on the rocky margin of Greenland enable measurement of vertical motion of the coastal area, which is an indicator of nearby mass loss. In this study, <span class="hlt">seasonal</span> melting variation of the Greenland <span class="hlt">ice</span> sheet (GrIS) is investigated using GPS vertical displacement data. Using a cubic spline fitting model, we retrieve three variables of the <span class="hlt">seasonal</span> melting pattern for GrIS from 1996 to 2010: date of the beginning and end of melt <span class="hlt">season</span>, length of melt <span class="hlt">season</span>, and amount of uplift in the melt <span class="hlt">season</span>. Data from three long -term sites on the periphery of Greenland show anomalously large uplift in 2010, implying significant melting in 2010. Preliminary results also show an early onset of melting in 2010, about 8 days earlier than the 1996-2009 average. In 2010, Greenland experienced a warmer and drier winter as well as a very warm summer, which presumably contributed to the anomalous <span class="hlt">ice</span> mass loss of 2010.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20060044086&hterms=percolation&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dpercolation','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20060044086&hterms=percolation&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dpercolation"><span id="translatedtitle">Mapping of <span class="hlt">ice</span> layer extent and snow accumulation in the percolation <span class="hlt">zone</span> of the Greenland <span class="hlt">ice</span> sheet</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nghiem, S. V.; Steffen, K.; Neumann, G.; Huff, R.</p> <p>2005-01-01</p> <p>The Greenland <span class="hlt">ice</span> sheet underwent record extensive melt in 2002 and prolonged melt in 2003. The severe melting created a significant and extensive <span class="hlt">ice</span> layer over the Greenland <span class="hlt">ice</span> sheet. An innovative approach is developed to detect the <span class="hlt">ice</span> layer formation using data acquired by the SeaWinds scatterometer on the QuikSCAT satellite. QuikSCAT backscatter together with in situ data from automatic weather stations of the Greenland Climate Network are used to map the extent of <span class="hlt">ice</span> layer formation. The results reveal areas of extensive <span class="hlt">ice</span> layer formed by the 2002 melt, which is consistent with the maximum melt extent in 2002. Moreover, during freezing <span class="hlt">seasons</span>, QuikSCAT data show a linear decrease in backscatter (in decibels or dB) that is related to the amount of snow accumulation in the <span class="hlt">ice</span> layer formation region. This snow accumulation signature is caused by the attenuation of radar waves in the snow layer, accumulating since the last major melt event, whose thickness appears as an exponential function in relation to the backscatter signature. We use the Greenland Climate Network data to calibrate the QuikSCAT accumulation rate in order to estimate and map snow accumulation. QuikSCAT results capture the extreme snowfall in mid-April 2003, which deposited more than 0.5 m of snow in a day as measured by the automated weather station at the NASA South East site. Large-scale QuikSCAT results show an anomalous increase of snow accumulation over the southeast region of Greenland during the 2002-2003 freezing <span class="hlt">season</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C54B..04K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C54B..04K"><span id="translatedtitle">Deformation of subglacial till near <span class="hlt">ice</span>-sheet grounding <span class="hlt">zones</span>: theory and experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kowal, K. N.; Worster, G.</p> <p>2015-12-01</p> <p>Large-scale <span class="hlt">ice</span>-sheet dynamics pivot on the deformation and transport of subglacial sediment through changes in the basal sliding velocities of glaciers. Such unconsolidated, water-saturated glacigenic sediment, or till, is found to accumulate into sedimentary wedges, or till-deltas, in grounding <span class="hlt">zones</span> separating floating <span class="hlt">ice</span> shelves from grounded <span class="hlt">ice</span> streams. In addition to affecting glacial slip, such sedimentation may serve to stabilise <span class="hlt">ice</span> sheets against grounding-line retreat in response to rising sea levels. We present a fluid-mechanical explanation of the formation of these wedges in terms of the jump in hydrostatic loading and unloading of till across the grounding <span class="hlt">zone</span>, and we compare our findings with geophysical data of sedimentary wedge formation at the modern-day grounding <span class="hlt">zone</span> of Whillans <span class="hlt">Ice</span> Stream, West Antarctica. We develop a theoretical model of wedge formation in which we treat both <span class="hlt">ice</span> and till as viscous fluids spreading under gravity into an inviscid ocean and find that a similar wedge of underlying fluid accumulates around the grounding line in our series of fluid-mechanical laboratory experiments. The experiments were performed in a confined channel geometry. We extend our theory to unconfined geometries in which till deformation is resisted dominantly by vertical shear stresses and the flow of the overlying <span class="hlt">ice</span> is resisted dominantly either by vertical shear stresses between the <span class="hlt">ice</span> and till or by extensional stresses characteristic of floating <span class="hlt">ice</span> shelves and shelfy streams. The former is relevant to less-lubricated, grounded <span class="hlt">ice</span> sheets whereas the latter is relevant to well-lubricated <span class="hlt">ice</span> streams, sliding over soft, deformable till of low viscosity and appreciable thickness. We formulate a local condition relating wedge slopes in each of the three scenarios and find a reasonable agreement with geophysical data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050169830','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050169830"><span id="translatedtitle">Tracking Retreat of the North <span class="hlt">Seasonal</span> <span class="hlt">Ice</span> Cap on Mars: Results from the THEMIS Investigation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ivanov, A. B.; Wagstaff, K. L.; Ttus, T. N.</p> <p>2005-01-01</p> <p>The CO2 <span class="hlt">ice</span> caps on Mars advance and retreat with the <span class="hlt">seasons</span>. This phenomenon was first observed by Cassini and then confirmed by numerous ground based observations in 19th and 20th centuries. With the advent of the space age observations of the <span class="hlt">seasonal</span> <span class="hlt">ice</span> cap were done by all orbiting spacecraft starting with Mariner 7. Viking Orbiters and more recently the Mars Global Surveyor (particularly Mars Orbiter Camera (MOC) and Thermal Emission Spectrometer (TES) instruments) have accumulated significant data on the retreat of the CO2 <span class="hlt">seasonal</span> cap. During Mars year 2 of THEMIS operations at Mars, we planned an observational campaign in which the THEMIS instrument (onboard the Mars Odyssey spacecraft) repeatedly observed the north <span class="hlt">seasonal</span> polar cap from midwinter to late spring. THEMIS allows simultaneous observations in both Thermal IR (12.57 m) and Visible wavelengths (0.65 m). One of the goals for this work is to initiate an interannual program for observations of the <span class="hlt">seasonal</span> <span class="hlt">ice</span> caps using the THEMIS instrument. The most efficient way to detect the edge between frost and bare ground is directly onboard of the spacecraft. Prior to onboard software design effort, we have developed two groundbased algorithms for automatically finding the edge of the <span class="hlt">seasonal</span> polar cap in THEMIS IR data. The first algorithm relies on fully calibrated data and can be used for highly reliable groundbased analyses. The second method was specifically developed for processing raw, uncalibrated data in a highly efficient way. It has the potential to enable automatic, onboard detections of the <span class="hlt">seasonal</span> cap retreat. We have experimentally confirmed that both methods produce similar results, and we have validated both methods against a model constructed from the MGS TES data from the same <span class="hlt">season</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1198287-modeling-impediment-methane-ebullition-bubbles-seasonal-lake-ice','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1198287-modeling-impediment-methane-ebullition-bubbles-seasonal-lake-ice"><span id="translatedtitle">Modeling the impediment of methane ebullition bubbles by <span class="hlt">seasonal</span> lake <span class="hlt">ice</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGESBeta</a></p> <p>Greene, S.; Walter Anthony, K. M.; Archer, D.; Sepulveda-Jauregui, A.; Martinez-Cruz, K.</p> <p>2014-07-15</p> <p>Microbial methane (CH4) ebullition (bubbling) from anoxic lake sediments comprises a globally significant flux to the atmosphere, but ebullition bubbles in temperate and polar lakes can be trapped by winter <span class="hlt">ice</span> cover and later released during spring thaw. This "<span class="hlt">ice</span>-bubble storage" (IBS) constitutes a novel mode of CH4 emission. Before bubbles are encapsulated by downward-growing <span class="hlt">ice</span>, some of their CH4 dissolves into the lake water, where it may be subject to oxidation. We present field characterization and a model of the annual CH4 cycle in Goldstream Lake, a thermokarst (thaw) lake in interior Alaska. We find that summertime ebullition dominatesmore » annual CH4 emissions to the atmosphere. Eighty percent of CH4 in bubbles trapped by <span class="hlt">ice</span> dissolves into the lake water column in winter, and about half of that is oxidized. The <span class="hlt">ice</span> growth rate and the magnitude of the CH4 ebullition flux are important controlling factors of bubble dissolution. Seven percent of annual ebullition CH4 is trapped as IBS and later emitted as <span class="hlt">ice</span> melts. In a future warmer climate, there will likely be less <span class="hlt">seasonal</span> <span class="hlt">ice</span> cover, less IBS, less CH4 dissolution from trapped bubbles, and greater CH4 emissions from northern lakes.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1197863-modeling-impediment-methane-ebullition-bubbles-seasonal-lake-ice','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1197863-modeling-impediment-methane-ebullition-bubbles-seasonal-lake-ice"><span id="translatedtitle">Modeling the impediment of methane ebullition bubbles by <span class="hlt">seasonal</span> lake <span class="hlt">ice</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGESBeta</a></p> <p>Greene, S.; Walter Anthony, K. M.; Archer, D.; Sepulveda-Jauregui, A.; Martinez-Cruz, K.</p> <p>2014-12-08</p> <p>Microbial methane (CH4) ebullition (bubbling) from anoxic lake sediments comprises a globally significant flux to the atmosphere, but ebullition bubbles in temperate and polar lakes can be trapped by winter <span class="hlt">ice</span> cover and later released during spring thaw. This "<span class="hlt">ice</span>-bubble storage" (IBS) constitutes a novel mode of CH4 emission. Before bubbles are encapsulated by downward-growing <span class="hlt">ice</span>, some of their CH4 dissolves into the lake water, where it may be subject to oxidation. We present field characterization and a model of the annual CH4 cycle in Goldstream Lake, a thermokarst (thaw) lake in interior Alaska. We find that summertime ebullition dominatesmore » annual CH4 emissions to the atmosphere. Eighty percent of CH4 in bubbles trapped by <span class="hlt">ice</span> dissolves into the lake water column in winter, and about half of that is oxidized. The <span class="hlt">ice</span> growth rate and the magnitude of the CH4 ebullition flux are important controlling factors of bubble dissolution. Seven percent of annual ebullition CH4 is trapped as IBS and later emitted as <span class="hlt">ice</span> melts. In a future warmer climate, there will likely be less <span class="hlt">seasonal</span> <span class="hlt">ice</span> cover, less IBS, less CH4 dissolution from trapped bubbles, and greater CH4 emissions from northern lakes.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9227L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9227L"><span id="translatedtitle">Upper Ocean Evolution Across the Beaufort Sea Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> from Autonomous Gliders</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Craig; Rainville, Luc; Perry, Mary Jane</p> <p>2016-04-01</p> <p>The observed reduction of Arctic summertime sea <span class="hlt">ice</span> extent and expansion of the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> (MIZ) have profound impacts on the balance of processes controlling sea <span class="hlt">ice</span> evolution, including the introduction of several positive feedback mechanisms that may act to accelerate melting. Examples of such feedbacks include increased upper ocean warming though absorption of solar radiation, elevated internal wave energy and mixing that may entrain heat stored in subsurface watermasses (e.g., the relatively warm Pacific Summer (PSW) and Atlantic (AW) waters), and elevated surface wave energy that acts to deform and fracture sea <span class="hlt">ice</span>. Spatial and temporal variability in <span class="hlt">ice</span> properties and open water fraction impact these processes. To investigate how upper ocean structure varies with changing <span class="hlt">ice</span> cover, and how the balance of processes shift as a function of <span class="hlt">ice</span> fraction and distance from open water, four long-endurance autonomous Seagliders occupied sections that extended from open water, through the marginal <span class="hlt">ice</span> <span class="hlt">zone</span>, deep into the pack during summer 2014 in the Beaufort Sea. Sections reveal strong fronts where cold, <span class="hlt">ice</span>-covered waters meet waters that have been exposed to solar warming, and O(10 km) scale eddies near the <span class="hlt">ice</span> edge. In the pack, Pacific Summer Water and a deep chlorophyll maximum form distinct layers at roughly 60 m and 80 m, respectively, which become increasingly diffuse as they progress through the MIZ and into open water. The isopynal layer between 1023 and 1024 kgm‑3, just above the PSW, consistently thickens near the <span class="hlt">ice</span> edge, likely due to mixing or energetic vertical exchange associated with strong lateral gradients in this region. This presentation will discuss the upper ocean variability, its relationship to sea <span class="hlt">ice</span> extent, and evolution over the summer to the start of freeze up.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT........93B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT........93B"><span id="translatedtitle">Using reanalysis data for the prediction of <span class="hlt">seasonal</span> wind turbine power losses due to <span class="hlt">icing</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Burtch, Daniel G.</p> <p></p> <p>The Northern Plains region of the United States is home to a significant amount of potential wind energy. However, in winter months capturing this potential power is severely impacted by the meteorological conditions, in the form of <span class="hlt">icing</span>. Predicting the expected loss in power production due to <span class="hlt">icing</span> is a valuable parameter that can be used in wind turbine operations, determination of wind turbine site locations and long-term energy estimates which are used for financing purposes. Currently, losses due to <span class="hlt">icing</span> must be estimated when developing predictions for turbine feasibility and financing studies, while <span class="hlt">icing</span> maps, a tool commonly used in Europe, are lacking in the United States. This study uses the Modern-Era Retrospective Analysis for Research and Applications (MERRA) dataset in conjunction with turbine production data and in-situ wind measurements to investigate six methods of predicting <span class="hlt">seasonal</span> losses (October-March) due to <span class="hlt">icing</span> at two sites located in Petersburg, ND and Valley City, ND. The prediction of <span class="hlt">icing</span> losses is based on temperature and relative humidity thresholds and is accomplished using six methods. Three methods use a Measure-Correlate-Predict (MCP) and flow model (WAsP) analysis for the determination of wind speeds and MERRA for temperature and relative humidity, while three methods use MERRA for all three variables. For each <span class="hlt">season</span> from 2002 to 2010, the predicted losses due to <span class="hlt">icing</span> are determined for a range of relative humidity thresholds and compared with observed <span class="hlt">icing</span> losses. An optimal relative humidity is then determined and tested on all <span class="hlt">seasons</span> from 2002 to 2013. The prediction methods are then compared to a common practice used in the wind energy industry of assuming a constant percentage loss for <span class="hlt">icing</span> over the same time period. The three methods using MERRA data alone show severe deficiencies in the accurate determination of wind speeds which leads to a large underprediction in accurate power output. Of the three MCP</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.A11L..07B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.A11L..07B"><span id="translatedtitle">Using Reanalysis Data for the Prediction of <span class="hlt">Seasonal</span> Wind Turbine Power Losses Due to <span class="hlt">Icing</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Burtch, D.; Mullendore, G. L.; Delene, D. J.; Storm, B.</p> <p>2013-12-01</p> <p>The Northern Plains region of the United States is home to a significant amount of potential wind energy. However, in winter months capturing this potential power is severely impacted by the meteorological conditions, in the form of <span class="hlt">icing</span>. Predicting the expected loss in power production due to <span class="hlt">icing</span> is a valuable parameter that can be used in wind turbine operations, determination of wind turbine site locations and long-term energy estimates which are used for financing purposes. Currently, losses due to <span class="hlt">icing</span> must be estimated when developing predictions for turbine feasibility and financing studies, while <span class="hlt">icing</span> maps, a tool commonly used in Europe, are lacking in the United States. This study uses the Modern-Era Retrospective Analysis for Research and Applications (MERRA) dataset in conjunction with turbine production data to investigate various methods of predicting <span class="hlt">seasonal</span> losses (October-March) due to <span class="hlt">icing</span> at two wind turbine sites located 121 km apart in North Dakota. The prediction of <span class="hlt">icing</span> losses is based on temperature and relative humidity thresholds and is accomplished using three methods. For each of the three methods, the required atmospheric variables are determined in one of two ways: using industry-specific software to correlate anemometer data in conjunction with the MERRA dataset and using only the MERRA dataset for all variables. For each <span class="hlt">season</span>, a percentage of the total expected generated power lost due to <span class="hlt">icing</span> is determined and compared to observed losses from the production data. An optimization is performed in order to determine the relative humidity threshold that minimizes the difference between the predicted and observed values. Eight <span class="hlt">seasons</span> of data are used to determine an optimal relative humidity threshold, and a further three <span class="hlt">seasons</span> of data are used to test this threshold. Preliminary results have shown that the optimized relative humidity threshold for the northern turbine is higher than the southern turbine for all methods</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JGRC..120.4803K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JGRC..120.4803K&link_type=ABSTRACT"><span id="translatedtitle">The effect of ocean heat flux on <span class="hlt">seasonal</span> <span class="hlt">ice</span> growth in Young Sound (Northeast Greenland)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kirillov, Sergei; Dmitrenko, Igor; Babb, David; Rysgaard, Søren; Barber, David</p> <p>2015-07-01</p> <p>The <span class="hlt">seasonal</span> <span class="hlt">ice</span> cover plays an important role in the climate system limiting the exchange of heat and momentum across the air-water interface. Among other factors, sea <span class="hlt">ice</span> is sensitive to the ocean heat flux. In this study, we use in situ oceanographic, sea <span class="hlt">ice</span>, and meteorological data collected during winter 2013/2014 in Young Sound (YS) fjord in Northeast Greenland to estimate the ocean heat flux to the landfast <span class="hlt">ice</span> cover. During the preceding <span class="hlt">ice</span>-free summer, incident solar radiation caused sea surface temperatures of up to 5-6°C. Subsequently, this heat was transferred down to the intermediate depths, but returned to the surface and retarded <span class="hlt">ice</span> growth throughout winter. Two different approaches were used to estimate the ocean heat fluxes; (i) a residual method based on a 1-D thermodynamic <span class="hlt">ice</span> growth model and (ii) a bulk parameterization using friction velocities and available heat content of water beneath the <span class="hlt">ice</span>. The average heat flux in the inner YS varied from 13 W m-2 in October-December to less than 2 W m-2 in January-May. An average heat flux of 9 W m-2 was calculated for the outer YS. Moreover, we show that the upward heat flux in the outer fjord is strongly modulated by surface outflow, which produced two maxima in heat flux (up to 18-24 W m-2) during 26 December to 27 January and from 11 February to 14 March. By May 2014, the upward ocean heat flux reduced the landfast <span class="hlt">ice</span> thickness by 18% and 24% in the inner and outer YS, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140008938','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140008938"><span id="translatedtitle">The Annual Glaciohydrology Cycle in the Ablation <span class="hlt">Zone</span> of the Greenland <span class="hlt">Ice</span> Sheet: Part 2. Observed and Modeled <span class="hlt">Ice</span> Flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Colgan, William Terence; Rajaram, Harihar; Anderson, Robert S.; Steffen, Konrad; Zwally, H. Jay; Phillips, Thomas; Abdalati, Waleed</p> <p>2012-01-01</p> <p><span class="hlt">Ice</span> velocities observed in 2005/06 at three GPS stations along the Sermeq Avannarleq flowline, West Greenland, are used to characterize an observed annual velocity cycle. We attempt to reproduce this annual <span class="hlt">ice</span> velocity cycle using a 1-D <span class="hlt">ice</span>-flow model with longitudinal stresses coupled to a 1-D hydrology model that governs an empirical basal sliding rule. <span class="hlt">Seasonal</span> basal sliding velocity is parameterized as a perturbation of prescribed winter sliding velocity that is proportional to the rate of change of glacier water storage. The coupled model reproduces the broad features of the annual basal sliding cycle observed along this flowline, namely a summer speed-up event followed by a fall slowdown event. We also evaluate the hypothesis that the observed annual velocity cycle is due to the annual calving cycle at the terminus. We demonstrate that the <span class="hlt">ice</span> acceleration due to a catastrophic calving event takes an order of magnitude longer to reach CU/ETH ('Swiss') Camp (46km upstream of the terminus) than is observed. The <span class="hlt">seasonal</span> acceleration observed at Swiss Camp is therefore unlikely to be the result of velocity perturbations propagated upstream via longitudinal coupling. Instead we interpret this velocity cycle to reflect the local history of glacier water balance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015BGeo...12.3009M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015BGeo...12.3009M&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Seasonal</span> dynamics of organic carbon and metals in thermokarst lakes from the discontinuous permafrost <span class="hlt">zone</span> of western Siberia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Manasypov, R. M.; Vorobyev, S. N.; Loiko, S. V.; Kritzkov, I. V.; Shirokova, L. S.; Shevchenko, V. P.; Kirpotin, S. N.; Kulizhsky, S. P.; Kolesnichenko, L. G.; Zemtzov, V. A.; Sinkinov, V. V.; Pokrovsky, O. S.</p> <p>2015-05-01</p> <p>Despite relatively good knowledge of the biogeochemistry of Siberian thermokarst lakes during summer base flow, their <span class="hlt">seasonal</span> dynamics remains almost unexplored. This work describes the chemical composition of ~130 thermokarst lakes ranging in size from a few m2 to several km2, located in the discontinuous permafrost <span class="hlt">zone</span>. Lakes were sampled during spring flood, just after the <span class="hlt">ice</span> break (early June), the end of summer (August), the beginning of <span class="hlt">ice</span> formation (October) and during the full freezing <span class="hlt">season</span> in winter (February). The lakes larger than 1000 m2 did not exhibit any statistically significant control of the lake size on dissolved organic carbon (DOC), the major and trace element concentrations over three major open water <span class="hlt">seasons</span>. On the annual scale, the majority of dissolved elements including organic carbon increased their concentration from 30 to 500%, with a statistically significant (p < 0.05) trend from spring to winter. The concentrations of most trace elements (TEs) increased in the order spring > summer > autumn > winter. The <span class="hlt">ice</span> formation in October included several stages: first, surface layer freezing followed by crack (fissure) formation with unfrozen water from the deeper layers spreading over the <span class="hlt">ice</span> surface. This water was subsequently frozen and formed layered <span class="hlt">ice</span> rich in organic matter. As a result, the DOC and metal (Mn, Fe, Ni, Cu, Zn, As, Ba and Pb) concentrations were highest near the surface of the <span class="hlt">ice</span> column (0 to 20 cm) and decreased by a factor of 2 towards the bottom. The main implications of discovered freeze-driven solute concentrations in thermokarst lake waters are enhanced colloidal coagulation and removal of dissolved organic matter and associated insoluble metals from the water column to the sediments. The measured distribution coefficients of a TE between amorphous organo-ferric coagulates and lake water (<0.45 μm) were similar to those reported earlier for Fe-rich colloids and low molecular weight (<1 kDa, or <1-2 nm</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1715613W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1715613W"><span id="translatedtitle">The impacts of intense moisture transport on the deep and marginal sea-<span class="hlt">ice</span> <span class="hlt">zones</span> of the Arctic during winter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Woods, Cian; Caballero, Rodrigo</p> <p>2015-04-01</p> <p> warming at the surface. There are an average of 14 such events that enter the polar cap each winter, driving about 50% of the <span class="hlt">seasonal</span> variation in surface temperature over the deep Arctic. We show that, over the last 30 years, the marginal <span class="hlt">ice-zones</span> in the Barents, Labrador and Chukchi Seas have experienced roughly a doubling in the frequency of these intense moisture intrusion events during winter. Interestingly, these are the regions that have experienced the most rapid wintertime <span class="hlt">ice</span> loss in the Arctic, raising the question: to what extent has the recent Arctic warming been driven by local vs. interannual/remote processes?</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C11A0346R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C11A0346R"><span id="translatedtitle">Upper Ocean Temperature, Salinity, and Turbulence Across the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> from Autonomous Seaglider Surveys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rainville, L.; Lee, C.</p> <p>2014-12-01</p> <p>We present initial results from several autonomous Seaglider deployments during summer 2014 in the <span class="hlt">ice</span>-free region, under <span class="hlt">ice</span>, and in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> (MIZ) of the Beaufort Sea. Measuring temperature and salinity of the upper ocean on scales of 2-3 km, these surveys resolve the short temporal and spatial scales associated with key upper ocean processes in the MIZ.Gliders also carry temperature and shear microstructure sensors, providing direct direct estimates of turbulent dissipation rates at the base of the surface mixed layer and in the halocline. The objective of this work to understand the balance and interplay of processes that supply freshwater and heat to the <span class="hlt">ice</span> ocean boundary layer and their variations as a function of <span class="hlt">ice</span> cover.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-05-31/pdf/2012-13160.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-05-31/pdf/2012-13160.pdf"><span id="translatedtitle">77 FR 32018 - Safety <span class="hlt">Zone</span>; Kemah Boardwalk Summer <span class="hlt">Season</span> Fireworks, Galveston Bay, Kemah, TX</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-05-31</p> <p>... INFORMATION: Table of Acronyms DHS Department of Homeland Security FR Federal Register NPRM Notice of Proposed... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety <span class="hlt">Zone</span>; Kemah Boardwalk Summer <span class="hlt">Season</span> Fireworks... mariners viewing the Kemah Boardwalk Summer <span class="hlt">Season</span> Fireworks. During periods of enforcement, entry into...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......253M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......253M"><span id="translatedtitle">Basal crevasses and suture <span class="hlt">zones</span> in the Larsen C <span class="hlt">Ice</span> Shelf, Antarctica: Implications for <span class="hlt">ice</span> shelf stability in a warming climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McGrath, Daniel J.</p> <p></p> <p>Understanding <span class="hlt">ice</span> shelf structure and processes is paramount to future predictions of sea level rise, as nearly 75% of the <span class="hlt">ice</span> flux from the Antarctic <span class="hlt">Ice</span> Sheet (AIS) passes through these gates. The breakup of an <span class="hlt">ice</span> shelf removes the longitudinal back stress acting on the grounded inland <span class="hlt">ice</span> and leads to flow acceleration, dynamic thinning and frontal retreat, processes that can be sustained for more than a decade. Increased <span class="hlt">ice</span> discharge to the ocean contributes to global sea level rise. This dissertation investigates basal crevasses and suture <span class="hlt">zones</span>, two key structural components of <span class="hlt">ice</span> shelves, in order to understand how the structure of an <span class="hlt">ice</span> shelf influences its stability in a warming climate. Ground penetrating radar, high-resolution satellite imagery and a variety of modeling approaches are utilized to assess these features on the Larsen C <span class="hlt">Ice</span> Shelf but in a manner that considers their influence on <span class="hlt">ice</span> shelf stability around the AIS. Basal crevasses are large-scale (~66% of <span class="hlt">ice</span> thickness and ten's of kms in length) and abundant features that are significant structural weaknesses. The viscoplastic deformation of the <span class="hlt">ice</span> shelf in response to the perturbed hydrostatic balance leads to the formation of both surface depressions and crevasses, hence weakening the <span class="hlt">ice</span> shelf further. Basal crevasses increase the local <span class="hlt">ice</span>-ocean interface by ~30%, thereby increasing basal roughness and altering <span class="hlt">ice</span>-ocean interactions. <span class="hlt">Ice</span>-shelf fractures frequently terminate where they encounter suture <span class="hlt">zones</span>, regions of material heterogeneity that form at the lateral bounds of meteoric inflows to <span class="hlt">ice</span> shelves. The termination of a 25 km-long rift in the Churchill Peninsula suture <span class="hlt">zone</span> is investigated and found to contain ~60 m of accreted marine <span class="hlt">ice</span>. Steady-state basal melting/freezing rates are determined for the <span class="hlt">ice</span> shelf and applied to a flowline model to examine the along-flow evolution of <span class="hlt">ice</span> shelf structure. The thickening surface wedge of locally accumulated meteoric <span class="hlt">ice</span></p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19890024800&hterms=salt+properties&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsalt%2Bproperties','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19890024800&hterms=salt+properties&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsalt%2Bproperties"><span id="translatedtitle">Numerical simulations of the profile properties of undeformed first-year sea <span class="hlt">ice</span> during the growth <span class="hlt">season</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cox, G. F. N.; Weeks, W. F.</p> <p>1988-01-01</p> <p>A model is presented for estimating salinity profiles for the first-year sea <span class="hlt">ice</span> during the growth <span class="hlt">season</span>, in which <span class="hlt">ice</span> growth equations were coupled with salt entrapment and brine drainage relations to obtain the relationship between the initial <span class="hlt">ice</span> salinity and the <span class="hlt">ice</span>-growth velocity and seawater salinity, as well as the subsequent drainage of brine from the <span class="hlt">ice</span>. The results obtained were found to be in reasonable agreement with field observations in that they showed characteristic C-shaped profiles similar to natural profiles. The average <span class="hlt">ice</span> salinity values were also in reasonable agreement with field data. The predicted <span class="hlt">ice</span> property profiles give composite plate properties that are significantly different from bulk property estimates that would result by assuming that sea <span class="hlt">ice</span> could be represented as a homogeneous plate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BGD....12.1653W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BGD....12.1653W"><span id="translatedtitle"><span class="hlt">Seasonality</span> of sea <span class="hlt">ice</span> controls interannual variability of summertime ΩA at the <span class="hlt">ice</span> shelf in the Eastern Weddell Sea - an ocean acidification sensitivity study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weeber, A.; Swart, S.; Monteiro, P. M. S.</p> <p>2015-01-01</p> <p>Increasing anthropogenic CO2 is decreasing surface water aragonite saturation state (ΩA), a growing concern for calcifying Euthecosome pteropods and its wider impact on Antarctic ecosystems. However, our understanding of the <span class="hlt">seasonal</span> cycle and interannual variability of this vulnerable ecosystem remains limited. This study examines surface water ΩA from four consecutive summers in the Eastern Weddell Gyre (EWG) <span class="hlt">ice</span> shelf region, and investigates the drivers and the role played by the <span class="hlt">seasonal</span> cycle in the interannual variability of ΩA. Interannual variability in the <span class="hlt">seasonal</span> phasing and the rate of summer sea <span class="hlt">ice</span> thaw was found to be the primary factor explaining interannual variability in surface water ΩA. In "optimal" summers when summer sea <span class="hlt">ice</span> thaw began in late November/early December (2008/2009 and 2010/2011), the summertime increase in ΩA was found to be 1.02, approximately double that from summers when sea <span class="hlt">ice</span> thaw was delayed to late December (2009/2010 and 2011/2012). We propose that the two critical climate (physical-biogeochemical) sensitivities for ΩA are the timing and the rate of sea <span class="hlt">ice</span> thaw, which has a direct impact on the mixed layer and the resulting onset and persistence of phytoplankton blooms. The strength of summertime carbonate saturation depends on <span class="hlt">seasonal</span> changes of sea <span class="hlt">ice</span>, stratification and primary production. The sensitivity of surface water biogeochemistry in this region to interannual changes in mixed layer - sea <span class="hlt">ice</span> processes, suggests that future trends in climate and the <span class="hlt">seasonal</span> cycle of sea <span class="hlt">ice</span>, combined with rapidly increasing anthropogenic CO2 will likely be a concern for the Antarctic <span class="hlt">ice</span> shelf ecosystem within the next few decades. If in the future, primary production is reduced and CO2 increased, our results suggest that in the EWG summertime surface water aragonite undersaturation will emerge by the middle of this century.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Icar..260..396B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Icar..260..396B"><span id="translatedtitle">Hemispheric asymmetry in martian <span class="hlt">seasonal</span> surface water <span class="hlt">ice</span> from MGS TES</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bapst, Jonathan; Bandfield, Joshua L.; Wood, Stephen E.</p> <p>2015-11-01</p> <p>The Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) visible/near-infrared and thermal infrared bolometers measured planetary broadband albedo and temperature for more than three Mars years. As <span class="hlt">seasons</span> progress on Mars, surface temperatures may fall below the frost point of volatiles in the atmosphere (namely, carbon dioxide and water). Systematic mapping of the spatial and temporal occurrence of these volatiles in the martian atmosphere, on the surface, and in the subsurface has shown their importance in understanding the climate of Mars. We examine TES daytime albedo, temperature, and atmospheric opacity data to map the latitudinal and temporal occurrence of <span class="hlt">seasonal</span> surface water frost on Mars. We expand on previous work by looking at the behavior of water frost over the entire martian year, made possible with comprehensive, multi-year data. Interpretations of frost are based on albedo changes and the corresponding daytime temperature range. Data is considered consistent with water frost when there are significant albedo increases (>0.05 relative to frost-free <span class="hlt">seasons</span>) and the observed temperatures are ∼170-200 K. We argue the presence of extensive water frost in the northern hemisphere, extending from the pole to ∼40°N, following <span class="hlt">seasonal</span> temperature trends. In the north, water frost first appears near the pole at Ls = ∼160° and is last observed at Ls = ∼90°. Extensive water frost is less evident in southern hemisphere data, though both hemispheres show data that are consistent with the presence of a water <span class="hlt">ice</span> annulus during <span class="hlt">seasonal</span> cap retreat. Hemispherical asymmetry in the occurrence of <span class="hlt">seasonal</span> water frost is due in part to the lower (∼40%) atmospheric water vapor abundances observed in the southern hemisphere. Our results are consistent with net transport of water vapor to the northern hemisphere. The deposition and sublimation of <span class="hlt">seasonal</span> water frost may significantly increase the near-surface water vapor density that could</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900060071&hterms=pigment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dpigment','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900060071&hterms=pigment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dpigment"><span id="translatedtitle"><span class="hlt">Seasonal</span> and interannual variability of pigment concentrations across a California Current frontal <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thomas, A. C.; Strub, P. T.</p> <p>1990-01-01</p> <p>The <span class="hlt">seasonal</span> and interannual variability of the latitudinal position of the California Current frontal <span class="hlt">zone</span> was investigated by examining satellite images of phytoplankton pigment from the coastal-<span class="hlt">zone</span> color scanner for the periods 1979-1983 and 1986. The pigment concentrations associated with the zonal front were also determined. A general <span class="hlt">seasonal</span> cycle of pigment concentrations is was established. It was found that variations in the frontal structure are controlled primarily by changes in pigment concentration north of the front. <span class="hlt">Seasonal</span> variations were found to be minimal south of the front, where pigment concentrations remain low throughout the spring, summer, and fall.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016TCry...10.1259A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016TCry...10.1259A"><span id="translatedtitle">Greenland <span class="hlt">Ice</span> Sheet <span class="hlt">seasonal</span> and spatial mass variability from model simulations and GRACE (2003-2012)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alexander, Patrick M.; Tedesco, Marco; Schlegel, Nicole-Jeanne; Luthcke, Scott B.; Fettweis, Xavier; Larour, Eric</p> <p>2016-06-01</p> <p>Improving the ability of regional climate models (RCMs) and <span class="hlt">ice</span> sheet models (ISMs) to simulate spatiotemporal variations in the mass of the Greenland <span class="hlt">Ice</span> Sheet (GrIS) is crucial for prediction of future sea level rise. While several studies have examined recent trends in GrIS mass loss, studies focusing on mass variations at sub-annual and sub-basin-wide scales are still lacking. At these scales, processes responsible for mass change are less well understood and modeled, and could potentially play an important role in future GrIS mass change. Here, we examine spatiotemporal variations in mass over the GrIS derived from the Gravity Recovery and Climate Experiment (GRACE) satellites for the January 2003-December 2012 period using a "mascon" approach, with a nominal spatial resolution of 100 km, and a temporal resolution of 10 days. We compare GRACE-estimated mass variations against those simulated by the Modèle Atmosphérique Régionale (MAR) RCM and the <span class="hlt">Ice</span> Sheet System Model (ISSM). In order to properly compare spatial and temporal variations in GrIS mass from GRACE with model outputs, we find it necessary to spatially and temporally filter model results to reproduce leakage of mass inherent in the GRACE solution. Both modeled and satellite-derived results point to a decline (of -178.9 ± 4.4 and -239.4 ± 7.7 Gt yr-1 respectively) in GrIS mass over the period examined, but the models appear to underestimate the rate of mass loss, especially in areas below 2000 m in elevation, where the majority of recent GrIS mass loss is occurring. On an <span class="hlt">ice</span>-sheet-wide scale, the timing of the modeled <span class="hlt">seasonal</span> cycle of cumulative mass (driven by summer mass loss) agrees with the GRACE-derived <span class="hlt">seasonal</span> cycle, within limits of uncertainty from the GRACE solution. However, on sub-<span class="hlt">ice</span>-sheet-wide scales, some areas exhibit significant differences in the timing of peaks in the annual cycle of mass change. At these scales, model biases, or processes not accounted for by models related</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFMGC11A0529W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFMGC11A0529W&link_type=ABSTRACT"><span id="translatedtitle">Projected Duration of the Sea-<span class="hlt">Ice</span>-Free <span class="hlt">Season</span> in the Future Alaskan Arctic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, M.; Overland, J. E.</p> <p>2014-12-01</p> <p>The change in the Arctic climate is fast and broad. Among many changes that have been observed, the reduction of sea <span class="hlt">ice</span> coverage has been one of the most significant factors. Continued reduction in sea <span class="hlt">ice</span> cover will probably result in longer open water duration, which is important for the shipping industry, marine mammals as well as other component of the local ecosystem. In this study we are to assess future sea <span class="hlt">ice</span> conditions, particularly the length of open water duration in the Alaskan Arctic over the next few decades using the latest coupled climate models (CMIP5). The Alaskan Arctic, including the Chukchi and the Beaufort Sea, has been a major region of summer sea <span class="hlt">ice</span> retreat since 2007. Based on the mean of 12 climate models, for the region north of the Bering Strait (70° N), future open-water duration may extend from a current 3-4 months to around five months by 2050. It is about one month shorter along the same latitude over the Beaufort Sea. The difference in the length of <span class="hlt">ice</span>-free <span class="hlt">season</span> between the north and the south will remain, but will be smaller in the 21st century compared with current condition. Open-water duration in the Alaskan Arctic expands quickly in these models over the next decades, in contrast to model under-predictions of sea <span class="hlt">ice</span> loss for the summer minimum over the Arctic wide domain. Uncertainty is generally ±one month estimated from the range of model results. Continued increases in open-water duration over the next two decades will impact regional economic access and potentially alter ecosystems, yet we need to keep in mind that from December through May most of the northern Alaskan Arctic will remain sea <span class="hlt">ice</span> covered into the second half of the century.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991JMS.....2....1C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991JMS.....2....1C"><span id="translatedtitle">Copepods in <span class="hlt">ice</span>-covered seas—Distribution, adaptations to <span class="hlt">seasonally</span> limited food, metabolism, growth patterns and life cycle strategies in polar seas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Conover, R. J.; Huntley, M.</p> <p>1991-07-01</p> <p>While a <span class="hlt">seasonal</span> <span class="hlt">ice</span> cover limits light penetration into both polar seas for up to ten months a year, its presence is not entirely negative. The mixed layer under sea <span class="hlt">ice</span> will generally be shallower than in open water at the same latitude and <span class="hlt">season</span>. <span class="hlt">Ice</span> forms a substrate on which primary production can be concentrated, a condition which contrasts with the generally dilute nutritional conditions which prevail in the remaining ocean. The combination of a shallow, generally stable mixed layer with a close proximity to abundant food make the under-<span class="hlt">ice</span> <span class="hlt">zone</span> a suitable nursery for both pelagic and benthic species, an upside-down benthos for opportunistic substrate browsers, and a rich feeding environment for species often considered to be neritic in temperate environments. Where the <span class="hlt">ice</span> cover is not continuous there may be a retreating <span class="hlt">ice</span> edge that facilitates the <span class="hlt">seasonal</span> production of phytoplankton primarily through increased stability from the melt water. <span class="hlt">Ice</span> edge blooms similarly encourage secondary production by pelagic animals. Pseudocalanus acuspes, which may be the most abundant and productive copepod in north polar latitudes, initiates growth at the start of the "spring bloom" of epontic algae, reaching sexual maturity at breakup or slightly before. In the Southern Hemisphere, the small neritic copepod Paralabidocera antarctica and adult krill have been observed to utilize <span class="hlt">ice</span> algae. Calanus hyperboreus breeds in the dark <span class="hlt">season</span> at depth and its buoyant eggs, slowly developing on the ascent, reach the under-<span class="hlt">ice</span> layer in April as nauplii ready to benefit from the primary production there. On the other hand, C. glacialis may initiate ontogenetic migrations and reproduction in response to increased erosion of <span class="hlt">ice</span> algae due to solar warming and melting at the <span class="hlt">ice</span>-water interface. While the same species in a phytoplankton bloom near the <span class="hlt">ice</span> edge reproduces actively, those under still-consolidated <span class="hlt">ice</span> nearby can have immature gonads. Diel migration and diel feeding</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70024509','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024509"><span id="translatedtitle"><span class="hlt">Seasonal</span> comparisons of sea <span class="hlt">ice</span> concentration estimates derived from SSM/I, OKEAN, and RADARSAT data</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Belchansky, G.I.; Douglas, D.C.</p> <p>2002-01-01</p> <p>The Special Sensor Microwave Imager (SSM/I) microwave satellite radiometer and its predecessor SMMR are primary sources of information for global sea <span class="hlt">ice</span> and climate studies. However, comparisons of SSM/I, Landsat, AVHRR, and ERS-1 synthetic aperture radar (SAR) have shown substantial <span class="hlt">seasonal</span> and regional differences in their estimates of sea <span class="hlt">ice</span> concentration. To evaluate these differences, we compared SSM/I estimates of sea <span class="hlt">ice</span> coverage derived with the NASA Team and Bootstrap algorithms to estimates made using RADARSAT, and OKEAN-01 satellite sensor data. The study area included the Barents Sea, Kara Sea, Laptev Sea, and adjacent parts of the Arctic Ocean, during October 1995 through October 1999. <span class="hlt">Ice</span> concentration estimates from spatially and temporally near-coincident imagery were calculated using independent algorithms for each sensor type. The OKEAN algorithm implemented the satellite's two-channel active (radar) and passive microwave data in a linear mixture model based on the measured values of brightness temperature and radar backscatter. The RADARSAT algorithm utilized a segmentation approach of the measured radar backscatter, and the SSM/I <span class="hlt">ice</span> concentrations were derived at National Snow and <span class="hlt">Ice</span> Data Center (NSIDC) using the NASA Team and Bootstrap algorithms. <span class="hlt">Seasonal</span> and monthly differences between SSM/I, OKEAN, and RADARSAT <span class="hlt">ice</span> concentrations were calculated and compared. Overall, total sea <span class="hlt">ice</span> concentration estimates derived independently from near-coincident RADARSAT, OKEAN-01, and SSM/I satellite imagery demonstrated mean differences of less than 5.5% (S.D. <9.5%) during the winter period. Differences between the SSM/I NASA Team and the SSM/I Bootstrap concentrations were no more than 3.1% (S.D. <5.4%) during this period. RADARSAT and OKEAN-01 data both yielded higher total <span class="hlt">ice</span> concentrations than the NASA Team and the Bootstrap algorithms. The Bootstrap algorithm yielded higher total <span class="hlt">ice</span> concentrations than the NASA Team algorithm. Total <span class="hlt">ice</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PolSc..10...43S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PolSc..10...43S"><span id="translatedtitle">Interannual variability in sea-<span class="hlt">ice</span> thickness in the pack-<span class="hlt">ice</span> <span class="hlt">zone</span> off Lützow-Holm Bay, East Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sugimoto, Fuko; Tamura, Takeshi; Shimoda, Haruhito; Uto, Shotaro; Simizu, Daisuke; Tateyama, Kazutaka; Hoshino, Seita; Ozeki, Toshihiro; Fukamachi, Yasushi; Ushio, Shuki; Ohshima, Kay I.</p> <p>2016-03-01</p> <p>Under the Japanese Antarctic Research Expedition (JARE) program, sea-<span class="hlt">ice</span> thickness has been routinely monitored off Lützow-Holm Bay (East Antarctica) during the summer (mid-December to early January) since 2000/01, using an electromagnetic induction (EM) instrument onboard the icebreaker Shirase. Analysis of these data over a 10-year period, combined with visual observations using a simplified form of the ASPeCt (Antarctic Sea <span class="hlt">ice</span> Processes and Climate) protocol, suggests a strong interannual variability in sea-<span class="hlt">ice</span> thickness in this region. For the repeat pack-<span class="hlt">ice</span> observation area, where the sea-<span class="hlt">ice</span> thickness averaged over the nine <span class="hlt">seasons</span> is ∼1.9 m, mean thicknesses of observed sea-<span class="hlt">ice</span> in 2010/11 and 2011/12 are exceptionally large, at ∼3.3 and ∼5.8 m, respectively. This result is strongly related to regional patterns of sea <span class="hlt">ice</span> dynamics. <span class="hlt">Ice</span> convergence caused by anomalous northerly winds was particularly high in 2011/12, suggesting that the extremely thick <span class="hlt">ice</span> observed in that <span class="hlt">season</span> resulted largely from sea-<span class="hlt">ice</span> deformation processes (including pressure ridging). Longer-term analysis of data from the past 34 years confirms that sea-<span class="hlt">ice</span> conditions and thickness off Lützow-Holm Bay in summer are determined mainly by the large-scale pattern of atmospheric pressure in December.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.P72C..06R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.P72C..06R"><span id="translatedtitle"><span class="hlt">Seasonally</span>-Active Water on Mars: Vapour, <span class="hlt">Ice</span>, Adsorbate, and the Possibility of Liquid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Richardson, M. I.</p> <p>2002-12-01</p> <p><span class="hlt">Seasonally</span>-active water can be defined to include any water reservoir that communicates with other reservoirs on time scales of a year or shorter. It is the interaction of these water reservoirs, under the influence of varying solar radiation and in conjunction with surface and atmospheric temperatures, that determines the phase-stability field for water at the surface, and the distribution of water in various forms below, on, and above the surface. The atmosphere is the critical, dynamical link in this cycling system, and also (fortunately) one of the easiest to observe. Viking and Mars Global Surveyor observations paint a strongly asymmetric picture of the global <span class="hlt">seasonal</span> water cycle, tied proximately to planetary eccentricity, and the existence of residual <span class="hlt">ice</span> caps of different composition at the two poles. The northern summer experiences the largest water vapour columns, and is associated with sublimation from the northern residual water <span class="hlt">ice</span> cap. The southern summer residual carbon dioxide <span class="hlt">ice</span> cap is cold trap for water. Asymmetry in the water cycle is an unsolved problem. Possible solutions may involve the current timing of perihelion (the water cap resides at the pole experiencing the longer but cooler summer), the trapping of water <span class="hlt">ice</span> in the northern hemisphere by tropical water <span class="hlt">ice</span> clouds, and the bias in the annual-average, zonal-mean atmospheric circulation resulting from the zonal-mean difference in the elevation of the northern and southern hemispheres. Adsorbed and frozen water have proven harder to constrain. Recent Odyssey Gamma Ray Spectrometer results suggest substantial ground <span class="hlt">ice</span> in the mid- and high-latitudes, but this water is likely below the <span class="hlt">seasonal</span> skin depth for two reasons: the GRS results are best fit with such a model, and GCM models of the water cycle produce dramatically unrealistic atmospheric vapour distributions when such a very near surface, GRS-like distribution is initialized - ultimately removing the water to the northern and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..43.7223B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.7223B"><span id="translatedtitle">Air-sea exchange of carbon dioxide in the Southern Ocean and Antarctic marginal <span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Butterworth, Brian J.; Miller, Scott D.</p> <p>2016-07-01</p> <p>Direct carbon dioxide flux measurements using eddy covariance from an icebreaker in the high-latitude Southern Ocean and Antarctic marginal <span class="hlt">ice</span> <span class="hlt">zone</span> are reported. Fluxes were combined with the measured water-air carbon dioxide partial pressure difference (ΔpCO2) to compute the air-sea gas transfer velocity (k, normalized to Schmidt number 660). The open water data showed a quadratic relationship between k (cm h-1) and the neutral 10 m wind speed (U10n, m s-1), kopen = 0.245 U10n2 + 1.3, in close agreement with decades old tracer-based results and much lower than cubic relationships inferred from previous open ocean eddy covariance studies. In the marginal <span class="hlt">ice</span> <span class="hlt">zone</span>, the effective gas transfer velocity decreased in proportion to sea <span class="hlt">ice</span> cover, in contrast with predictions of enhanced gas exchange in the presence of sea <span class="hlt">ice</span>. The combined open water and marginal <span class="hlt">ice</span> <span class="hlt">zone</span> results affect the calculated magnitude and spatial distribution of Southern Ocean carbon flux.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120009100','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120009100"><span id="translatedtitle">The Annual Glaciohydrology Cycle in the Ablation <span class="hlt">Zone</span> of the Greenland <span class="hlt">Ice</span> Sheet: Part 1. Hydrology Model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Colgan, William; Rajaram, Harihar; Anderson, Robert; Steffen. Konrad; Phillips, Thomas; Zwally, H. Jay; Abdalati, Waleed</p> <p>2012-01-01</p> <p>We apply a novel one-dimensional glacier hydrology model that calculates hydraulic head to the tidewater-terminating Sermeq Avannarleq flowline of the Greenland <span class="hlt">ice</span> sheet. Within a plausible parameter space, the model achieves a quasi-steady-state annual cycle in which hydraulic head oscillates close to flotation throughout the ablation <span class="hlt">zone</span>. Flotation is briefly achieved during the summer melt <span class="hlt">season</span> along a approx.17 km stretch of the approx.50 km of flowline within the ablation <span class="hlt">zone</span>. Beneath the majority of the flowline, subglacial conduit storage closes (i.e. obtains minimum radius) during the winter and opens (i.e. obtains maximum radius) during the summer. Along certain stretches of the flowline, the model predicts that subglacial conduit storage remains open throughout the year. A calculated mean glacier water residence time of approx.2.2 years implies that significant amounts of water are stored in the glacier throughout the year. We interpret this residence time as being indicative of the timescale over which the glacier hydrologic system is capable of adjusting to external surface meltwater forcings. Based on in situ <span class="hlt">ice</span> velocity observations, we suggest that the summer speed-up event generally corresponds to conditions of increasing hydraulic head during inefficient subglacial drainage. Conversely, the slowdown during fall generally corresponds to conditions of decreasing hydraulic head during efficient subglacial drainage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016OcDyn..66..839G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016OcDyn..66..839G"><span id="translatedtitle">Wave observation in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> with the TerraSAR-X satellite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gebhardt, Claus; Bidlot, Jean-Raymond; Gemmrich, Johannes; Lehner, Susanne; Pleskachevsky, Andrey; Rosenthal, Wolfgang</p> <p>2016-07-01</p> <p>This article investigates the penetration of ocean waves into the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> (MIZ), observed by satellite, and likewise provides a basis for the future cross-validation of respective models. To this end, synthetic aperture radar images from the TerraSAR-X satellite (TS-X) and numerical simulations of the European Centre for Medium-Range Weather Forecasts (ECMWF) are used. The focus is an event of swell waves, developed during a storm passage in the Atlantic, penetrating deeply into the MIZ off the coast of Eastern Greenland in February 2013. The TS-X scene which is the basis for this investigation extends from the <span class="hlt">ice</span>-free open ocean to solid <span class="hlt">ice</span>. The variation of the peak wavelength is analysed and potential sources of variability are discussed. We find an increase in wavelength which is consistent with the spatial dispersion of deep water waves, even within the <span class="hlt">ice</span>-covered region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoRL..43.5151S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoRL..43.5151S&link_type=ABSTRACT"><span id="translatedtitle">Airborne remote sensing of ocean wave directional wavenumber spectra in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sutherland, Peter; Gascard, Jean-Claude</p> <p>2016-05-01</p> <p>Interactions between surface waves and sea <span class="hlt">ice</span> are thought to be an important, but poorly understood, physical process in the atmosphere-<span class="hlt">ice</span>-ocean system. In this work, airborne scanning lidar was used to observe ocean waves propagating into the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> (MIZ). These represent the first direct spatial measurements of the surface wavefield in the polar MIZ. Data were compared against two attenuation models, one based on viscous dissipation and one based on scattering. Both models were capable of reproducing the measured wave energy. The observed wavenumber dependence of attenuation was found to be consistent with viscous processes, while the spectral spreading of higher wavenumbers suggested a scattering mechanism. Both models reproduced a change in peak direction due to preferential directional filtering. Floe sizes were recorded using colocated visible imagery, and their distribution was found to be consistent with <span class="hlt">ice</span> breakup by the wavefield.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27458438','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27458438"><span id="translatedtitle">Unanticipated Geochemical and Microbial Community Structure under <span class="hlt">Seasonal</span> <span class="hlt">Ice</span> Cover in a Dilute, Dimictic Arctic Lake.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schütte, Ursel M E; Cadieux, Sarah B; Hemmerich, Chris; Pratt, Lisa M; White, Jeffrey R</p> <p>2016-01-01</p> <p>Despite most lakes in the Arctic being perennially or <span class="hlt">seasonally</span> frozen for at least 40% of the year, little is known about microbial communities and nutrient cycling under <span class="hlt">ice</span> cover. We assessed the vertical microbial community distribution and geochemical composition in early spring under <span class="hlt">ice</span> in a <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered lake in southwest Greenland using amplicon-based sequencing that targeted 16S rRNA genes and using a combination of field and laboratory aqueous geochemical methods. Microbial communities changed consistently with changes in geochemistry. Composition of the abundant members responded strongly to redox conditions, shifting downward from a predominantly heterotrophic aerobic community in the suboxic waters to a heterotrophic anaerobic community in the anoxic waters. Operational taxonomic units (OTUs) of Sporichthyaceae, Comamonadaceae, and the SAR11 Clade had higher relative abundances above the oxycline and OTUs within the genus Methylobacter, the phylum Lentisphaerae, and purple sulfur bacteria (PSB) below the oxycline. Notably, a 13-fold increase in sulfide at the oxycline was reflected in an increase and change in community composition of potential sulfur oxidizers. Purple non-sulfur bacteria were present above the oxycline and green sulfur bacteria and PSB coexisted below the oxycline, however, PSB were most abundant. For the first time we show the importance of PSB as potential sulfur oxidizers in an Arctic dimictic lake. PMID:27458438</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27458438','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27458438"><span id="translatedtitle">Unanticipated Geochemical and Microbial Community Structure under <span class="hlt">Seasonal</span> <span class="hlt">Ice</span> Cover in a Dilute, Dimictic Arctic Lake.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schütte, Ursel M E; Cadieux, Sarah B; Hemmerich, Chris; Pratt, Lisa M; White, Jeffrey R</p> <p>2016-01-01</p> <p>Despite most lakes in the Arctic being perennially or <span class="hlt">seasonally</span> frozen for at least 40% of the year, little is known about microbial communities and nutrient cycling under <span class="hlt">ice</span> cover. We assessed the vertical microbial community distribution and geochemical composition in early spring under <span class="hlt">ice</span> in a <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered lake in southwest Greenland using amplicon-based sequencing that targeted 16S rRNA genes and using a combination of field and laboratory aqueous geochemical methods. Microbial communities changed consistently with changes in geochemistry. Composition of the abundant members responded strongly to redox conditions, shifting downward from a predominantly heterotrophic aerobic community in the suboxic waters to a heterotrophic anaerobic community in the anoxic waters. Operational taxonomic units (OTUs) of Sporichthyaceae, Comamonadaceae, and the SAR11 Clade had higher relative abundances above the oxycline and OTUs within the genus Methylobacter, the phylum Lentisphaerae, and purple sulfur bacteria (PSB) below the oxycline. Notably, a 13-fold increase in sulfide at the oxycline was reflected in an increase and change in community composition of potential sulfur oxidizers. Purple non-sulfur bacteria were present above the oxycline and green sulfur bacteria and PSB coexisted below the oxycline, however, PSB were most abundant. For the first time we show the importance of PSB as potential sulfur oxidizers in an Arctic dimictic lake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4932660','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4932660"><span id="translatedtitle">Unanticipated Geochemical and Microbial Community Structure under <span class="hlt">Seasonal</span> <span class="hlt">Ice</span> Cover in a Dilute, Dimictic Arctic Lake</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Schütte, Ursel M. E.; Cadieux, Sarah B.; Hemmerich, Chris; Pratt, Lisa M.; White, Jeffrey R.</p> <p>2016-01-01</p> <p>Despite most lakes in the Arctic being perennially or <span class="hlt">seasonally</span> frozen for at least 40% of the year, little is known about microbial communities and nutrient cycling under <span class="hlt">ice</span> cover. We assessed the vertical microbial community distribution and geochemical composition in early spring under <span class="hlt">ice</span> in a <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered lake in southwest Greenland using amplicon-based sequencing that targeted 16S rRNA genes and using a combination of field and laboratory aqueous geochemical methods. Microbial communities changed consistently with changes in geochemistry. Composition of the abundant members responded strongly to redox conditions, shifting downward from a predominantly heterotrophic aerobic community in the suboxic waters to a heterotrophic anaerobic community in the anoxic waters. Operational taxonomic units (OTUs) of Sporichthyaceae, Comamonadaceae, and the SAR11 Clade had higher relative abundances above the oxycline and OTUs within the genus Methylobacter, the phylum Lentisphaerae, and purple sulfur bacteria (PSB) below the oxycline. Notably, a 13-fold increase in sulfide at the oxycline was reflected in an increase and change in community composition of potential sulfur oxidizers. Purple non-sulfur bacteria were present above the oxycline and green sulfur bacteria and PSB coexisted below the oxycline, however, PSB were most abundant. For the first time we show the importance of PSB as potential sulfur oxidizers in an Arctic dimictic lake. PMID:27458438</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PCE....83...75G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PCE....83...75G"><span id="translatedtitle">Various remote sensing approaches to understanding roughness in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gupta, Mukesh</p> <p></p> <p>Multi-platform based measurement approaches to understanding complex marginal <span class="hlt">ice</span> <span class="hlt">zone</span> (MIZ) are suggested in this paper. Physical roughness measurements using ship- and helicopter-based laser systems combined with ship-based active microwave backscattering (C-band polarimetric coherences) and dual-polarized passive microwave emission (polarization ratio, PR and spectral gradient ratios, GR at 37 and 89 GHz) are presented to study diverse sea <span class="hlt">ice</span> types found in the MIZ. Autocorrelation functions are investigated for different sea <span class="hlt">ice</span> roughness types. Small-scale roughness classes were discriminated using data from a ship-based laser profiler. The polarimetric coherence parameter ρHHVH , is not found to exhibit any observable sensitivity to the surface roughness for all incidence angles. Rubble-ridges, pancake <span class="hlt">ice</span>, snow-covered frost flowers, and dense frost flowers exhibit separable signatures using GR-H and GR-V at >70° incidence angles. This paper diagnosed changes in sea <span class="hlt">ice</span> roughness on a spatial scale of ∼0.1-4000 m and on a temporal scale of ∼1-240 days (<span class="hlt">ice</span> freeze-up to summer melt). The coupling of MIZ wave roughness and aerodynamic roughness in conjunction with microwave emission and backscattering are future avenues of research. Additionally, the integration of various datasets into thermodynamic evolution model of sea <span class="hlt">ice</span> will open pathways to successful development of inversion models of MIZ behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989EOSTr..70..545M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989EOSTr..70..545M"><span id="translatedtitle">MIZEX East 1987: Winter Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> Program in the Fram Strait and Greenland Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>MIZEX'87 Group</p> <p></p> <p>The overall objective o f MIZEX is to gain a better understanding of the mesoscale physical and biological processes by which atmosphere, <span class="hlt">ice</span>, and ocean interact in the marginal <span class="hlt">ice</span> <span class="hlt">zones</span> (MIZ) that are found at the boundaries between <span class="hlt">ice</span>-covered and open oceans. Improved modeling and better prediction of <span class="hlt">ice</span>-edge position, <span class="hlt">ice</span> concentration, and <span class="hlt">ice</span> type in these regions would be a major step toward expanding human activities, for example, seaborne commerce, fishing, oil exploration and production, and naval operations. In addition, when more accurate parameterizations of mesoscale physical processes are available for inclusion in large-scale models, the result will be a major improvement in hemispherical climatological studies.Winter MIZEX '87 was conducted during March and April 1987 in the Fram Strait and Greenland Sea (see cover) and extended along the MIZ from about 75°N-79°N and 5°W-5°E. The experiment included an intensive 2-day investigation of the Barents Sea MIZ carried out between the southern tip of Svalbard and Bear Island. Two Norwegian ships, R/V Håakon Mosby and the <span class="hlt">ice</span>-strengthened R/V Polar Circle, and the R/V Valdivia of the Federal Republic of Germany participated in the experiment. Flight operations were carried out by two Canadian aircraft equipped with Synthetic Aperature Radar (SAR), a U.S. plane equipped with passive microwave sensors, a Norwegian P3 aircraft, and a helicopter based on the Polar Circle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C11A0349S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C11A0349S"><span id="translatedtitle">The Floe Size Distribution in the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> of the Beaufort and Chukchi Seas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schweiger, A. J. B.; Stern, H. L., III; Stark, M.; Zhang, J.; Steele, M.; Hwang, P. B.</p> <p>2014-12-01</p> <p>Several key processes in the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> (MIZ) of the Arctic Ocean are related to the size of the <span class="hlt">ice</span> floes, whose diameters range from meters to tens of kilometers. The floe size distribution (FSD) influences the mechanical properties of the <span class="hlt">ice</span> cover, air-sea momentum and heat transfer, lateral melting, and light penetration. However, no existing sea-<span class="hlt">ice</span>/ocean models currently simulate the FSD in the MIZ. Model development depends on observations of the FSD for parameterization, calibration, and validation. To support the development and implementation of the FSD in the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> Modeling and Assimilation System (MIZMAS), we have analyzed the FSD in the Beaufort and Chukchi seas using multiple sources of satellite imagery: NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua satellites (250 m pixel size), the USGS Landsat 8 satellite (80 m pixel size), the Canadian Space Agency's synthetic aperture radar (SAR) on RADARSAT (50 meter pixel size), and declassified National Technical Means imagery from the Global Fiducials Library (GFL) of the USGS (1 m pixel size). The procedure for identifying <span class="hlt">ice</span> floes in the imagery begins with manually delineating cloud-free regions (if necessary). A threshold is then chosen to separate <span class="hlt">ice</span> from water. Morphological operations and other semi-automated techniques are used to identify individual floes, whose properties are then easily calculated. We use the mean caliper diameter as the measure of floe size. The FSD is adequately described by a power-law in which the exponent characterizes the relative number of large and small floes. Changes in the exponent over time and space reflect changes in physical processes in the MIZ, such as sea-<span class="hlt">ice</span> deformation, fracturing, and melting. We report results of FSD analysis for the spring and summer of 2013 and 2014, and show how the FSD will be incorporated into the MIZMAS model.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26342133','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26342133"><span id="translatedtitle">Winter severity determines functional trait composition of phytoplankton in <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered lakes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Özkundakci, Deniz; Gsell, Alena S; Hintze, Thomas; Täuscher, Helgard; Adrian, Rita</p> <p>2016-01-01</p> <p>How climate change will affect the community dynamics and functionality of lake ecosystems during winter is still little understood. This is also true for phytoplankton in <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered temperate lakes which are particularly vulnerable to the presence or absence of <span class="hlt">ice</span>. We examined changes in pelagic phytoplankton winter community structure in a north temperate lake (Müggelsee, Germany), covering 18 winters between 1995 and 2013. We tested how phytoplankton taxa composition varied along a winter-severity gradient and to what extent winter severity shaped the functional trait composition of overwintering phytoplankton communities using multivariate statistical analyses and a functional trait-based approach. We hypothesized that overwintering phytoplankton communities are dominated by taxa with trait combinations corresponding to the prevailing winter water column conditions, using <span class="hlt">ice</span> thickness measurements as a winter-severity indicator. Winter severity had little effect on univariate diversity indicators (taxon richness and evenness), but a strong relationship was found between the phytoplankton community structure and winter severity when taxon trait identity was taken into account. Species responses to winter severity were mediated by the key functional traits: motility, nutritional mode, and the ability to form resting stages. Accordingly, one or the other of two functional groups dominated the phytoplankton biomass during mild winters (i.e., thin or no <span class="hlt">ice</span> cover; phototrophic taxa) or severe winters (i.e., thick <span class="hlt">ice</span> cover; exclusively motile taxa). Based on predicted milder winters for temperate regions and a reduction in <span class="hlt">ice</span>-cover durations, phytoplankton communities during winter can be expected to comprise taxa that have a relative advantage when the water column is well mixed (i.e., need not be motile) and light is less limiting (i.e., need not be mixotrophic). A potential implication of this result is that winter severity promotes different</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26342133','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26342133"><span id="translatedtitle">Winter severity determines functional trait composition of phytoplankton in <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered lakes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Özkundakci, Deniz; Gsell, Alena S; Hintze, Thomas; Täuscher, Helgard; Adrian, Rita</p> <p>2016-01-01</p> <p>How climate change will affect the community dynamics and functionality of lake ecosystems during winter is still little understood. This is also true for phytoplankton in <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered temperate lakes which are particularly vulnerable to the presence or absence of <span class="hlt">ice</span>. We examined changes in pelagic phytoplankton winter community structure in a north temperate lake (Müggelsee, Germany), covering 18 winters between 1995 and 2013. We tested how phytoplankton taxa composition varied along a winter-severity gradient and to what extent winter severity shaped the functional trait composition of overwintering phytoplankton communities using multivariate statistical analyses and a functional trait-based approach. We hypothesized that overwintering phytoplankton communities are dominated by taxa with trait combinations corresponding to the prevailing winter water column conditions, using <span class="hlt">ice</span> thickness measurements as a winter-severity indicator. Winter severity had little effect on univariate diversity indicators (taxon richness and evenness), but a strong relationship was found between the phytoplankton community structure and winter severity when taxon trait identity was taken into account. Species responses to winter severity were mediated by the key functional traits: motility, nutritional mode, and the ability to form resting stages. Accordingly, one or the other of two functional groups dominated the phytoplankton biomass during mild winters (i.e., thin or no <span class="hlt">ice</span> cover; phototrophic taxa) or severe winters (i.e., thick <span class="hlt">ice</span> cover; exclusively motile taxa). Based on predicted milder winters for temperate regions and a reduction in <span class="hlt">ice</span>-cover durations, phytoplankton communities during winter can be expected to comprise taxa that have a relative advantage when the water column is well mixed (i.e., need not be motile) and light is less limiting (i.e., need not be mixotrophic). A potential implication of this result is that winter severity promotes different</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H41F1107J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H41F1107J"><span id="translatedtitle">Groundwater-Stream Interactions in a <span class="hlt">Seasonal</span> Flooded Riparian <span class="hlt">Zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jensen, J. K.; Engesgaard, P. K.; Nilsson, B.</p> <p>2011-12-01</p> <p>At Odense River in Denmark several wetlands/riparian <span class="hlt">zones</span> have recently been reconstructed with one objective to rehabilitate the wetland/riparian <span class="hlt">zone</span> as a buffer strip enhancing depletion of agricultural inputs of diffuse pollutants like nutrients and pesticides to the receiving Odense River. The approach is initiated to either force the polluted groundwater through a reactive buffer strip and/or allowing polluted river water to flood and infiltrate the reactive riparian <span class="hlt">zone</span>. However, often the hydraulics of these systems is poorly understood and therefore it is difficult to evaluate the efficiency of the systems and several questions often remain unanswered; Is residence time in the riparian <span class="hlt">zone</span> long enough to sufficiently deplete the pollutants? What are the effects of flooding and infiltration of polluted river water on the hydraulics of the buffer strip? Can differences in groundwater flow paths in periods with flooding reduce the effect of the buffer strip by shortening flow paths to the surface water and hence alter residence time; that is, does groundwater-stream interaction change during and after flooding? And finally; is it possible to upscale the overall effect for a whole river system? Monitoring is ongoing in a reconstructed riparian <span class="hlt">zone</span> heavily polluted with nitrate as a part of the EU project AQUAREHAB. The setup is a grid of 50 piezometers installed in selected transects following groundwater flow paths from an adjacent agricultural site to the river. The piezometer setup permits us to follow the changes in hydraulic heads and to perform water sampling for chemical characterization. The site has been characterized by geophysical Multi-Electrode-Profiling and correlated to two geotechnical drillings to depths of 20 m, by slug-test, and hydro periods have been determined from continuous recording of river stage. Temperature is used as a tracer for monitoring discharge of groundwater to the stream (non-continuous converted to an estimate of flux</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050167779','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050167779"><span id="translatedtitle">Mars Water <span class="hlt">Ice</span> and Carbon Dioxide <span class="hlt">Seasonal</span> Polar Caps: GCM Modeling and Comparison with Mars Express Omega Observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Forget, F.; Levrard, B.; Montmessin, F.; Schmitt, B.; Doute, S.; Langevin, Y.; Bibring, J. P.</p> <p>2005-01-01</p> <p>To better understand the behavior of the Mars CO2 <span class="hlt">ice</span> <span class="hlt">seasonal</span> polar caps, and in particular interpret the the Mars Express Omega observations of the recession of the northern <span class="hlt">seasonal</span> cap, we present some simulations of the Martian Climate/CO2 cycle/ water cycle as modeled by the Laboratoire de Meteorologie Dynamique (LMD) global climate model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.A53C0391Y&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.A53C0391Y&link_type=ABSTRACT"><span id="translatedtitle">A Regional Model for <span class="hlt">Seasonal</span> Sea <span class="hlt">Ice</span> Prediction in the Pacific Sector of the Arctic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yuan, X.; Li, Y.; Chen, D.; Zhang, Q.; Li, C.; Niu, F.; Sun, Y.</p> <p>2015-12-01</p> <p>The recent results from a linear Markov model for <span class="hlt">seasonal</span> prediction of pan-Arctic sea <span class="hlt">ice</span> concentration (SIC) show that sea <span class="hlt">ice</span> in the Pacific sector has the lowest predictability compared to other regions. One reason could be that the climate variability in the Atlantic sector is so dominant that other signals in the Arctic climate system do not appear in the leading modes used for model construction. This study develops a regional Markov model to improve <span class="hlt">seasonal</span> forecasting of SIC in the Pacific sector. The model climate system consists of various combinations of the monthly mean series of SIC, sea surface temperature (SST), surface air temperature (SAT), pressure/geopotential height fields and winds at pressure levels. Multivariate empirical orthogonal functions (MEOF) and rotated MEOF are applied to each set of data to reduce the model dimensions. After a series of experiments, the final model configuration selects 23 rotated MEOF modes from a data matrix of three variables (SIC, SST and SAT). This regional model shows considerable improvement in the prediction skill in the Pacific sector in all <span class="hlt">seasons</span>. The anomaly correlation skill increases by 0.2 at 1- to 4-month leads in the Bering Sea, and by 0.1 at 1- to 10-month leads in the Sea of Okhotsk. In general, the model performs better in summer and fall than in winter and spring. On average, the correlation skill can reach 0.6 at a 2-month (4-month) lead in the Bering Sea (the Sea of Okhotsk).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRD..119.6563C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRD..119.6563C"><span id="translatedtitle">Assessing the role of sublimation in the dry snow <span class="hlt">zone</span> of the Greenland <span class="hlt">ice</span> sheet in a warming world</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cullen, Nicolas J.; Mölg, Thomas; Conway, Jonathan; Steffen, Konrad</p> <p>2014-06-01</p> <p>Meteorological and glaciological data obtained over an intensive 2 year measurement period (2000-2002) are used to run a physically based climatic mass balance model to characterize a <span class="hlt">seasonal</span> variability in mass and energy exchanges at Summit, Greenland. The model resolves the full surface energy balance and the subsurface temperature profile by inclusion of energy release from penetrating shortwave radiation. A Monte Carlo approach using 1000 different parameter combinations is adopted to assess model uncertainty, with output compared to measured surface and subsurface temperatures, changes in surface height, and eddy correlation data. The heat exchanges associated with the change in phase of water are very small in all <span class="hlt">seasons</span>, with the average turbulent latent heat flux equal to 0.4 (±0.2) W m-2. This suggests that the mean annual water vapor gradient is toward the surface, resulting in a mass gain of 4.1 mm WE yr-1. The mass gain represents only a small fraction of the total accumulation (<2%), in part because of the change in sign of the water vapor flux from winter (deposition) to summer (sublimation), but if assumed to be typical of the entire dry snow <span class="hlt">zone</span> (40% of the total <span class="hlt">ice</span> sheet area) is equivalent to approximately 5.5 Gt yr-1. A simple experiment based on 2012 atmospheric conditions suggests that mass turnover from water vapor exchanges will likely be enhanced in a warming climate, with sublimation increasing more than deposition. Should the sign of the mean turbulent latent heat flux change due to warming, the present mass gain in the dry snow <span class="hlt">zone</span> could easily become a mass loss of equal proportion, which would further enhance the negative mass balance of the Greenland <span class="hlt">ice</span> sheet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998DSRI...45.1357C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998DSRI...45.1357C"><span id="translatedtitle">Changes in lipid composition of copepods and Euphausia superba associated with diet and environmental conditions in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span>, Bellingshausen Sea, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cripps, G. C.; Hill, H. J.</p> <p>1998-08-01</p> <p>The effect of varying diet and environmental conditions at the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> (MIZ) on the fatty acid and hydrocarbon compositions of five species of copepod and krill, Euphausia superba, was investigated. Zooplankton at the MIZ experienced a range of conditions, from a low algal biomass (mainly flagellates) under pack-<span class="hlt">ice</span> to a spring bloom dominated by diatoms in the open ocean. Principal Component Analysis classified the copepods into three dietary regimes: (i) omnivores or general algal feeders under the pack <span class="hlt">ice</span>, (ii) dinoflagellate feeders, and (iii) diatom feeders in the open ocean. This classification was supported by the distribution of the diatom marker n-heneicosahexaene ( n-C 21:6) and a general indicator of herbivory, the isoprenoid pristane. The fatty acid and hydrocarbon composition reflected dietary preferences and availability as the <span class="hlt">season</span> progressed. Of the copepods under the pack-<span class="hlt">ice</span>, Oithona spp. was omnivorous whereas Calanus propinquus was feeding preferentially on flagellates. Metridia gerlachei fed on flagellates in all conditions, but also included diatoms in its diet during the bloom. Calanoides acutus and Rhincalanus gigas, which passed the winter in diapause, were feeding almost exclusively on diatoms in the open ocean. Euphausia superba, which were also mainly diatom feeders in the open ocean, were feeding on the sea-<span class="hlt">ice</span> algae (diatoms) and suspended material from the water column (dinoflagellates) under the pack-<span class="hlt">ice</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.C11A..08T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.C11A..08T"><span id="translatedtitle">Bathymetry of Grounding <span class="hlt">Zones</span> and Sub-<span class="hlt">Ice</span> Shelf Cavities of the Amundsen Sea, from Operation <span class="hlt">Ice</span>Bridge Gravity Inversions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tinto, K. J.; Cochran, J. R.; Bell, R. E.</p> <p>2012-12-01</p> <p>In order to understand the observed changes in thinning and grounding line position of outlet glaciers it is essential to have accurate maps of the bathymetry of the sea floor within and around the grounding <span class="hlt">zone</span>. This bathymetry controls the stability of the grounding line as well as access and circulation of seawater under their stabilizing <span class="hlt">ice</span> shelves. Since 2009 Operation <span class="hlt">Ice</span>Bridge has flown gridded surveys over four of the <span class="hlt">ice</span> shelves of the Amundsen Sea embayment. We present a 3D inversion of the gravity from the region, supplemented by 2D profile models across the <span class="hlt">ice</span> shelves to provide a self-consistent bathymetric model of the grounding <span class="hlt">zone</span> and sub <span class="hlt">ice</span> cavity of Pine Island, Thwaites, Dotson and Crosson <span class="hlt">ice</span> shelves. Much attention has been paid to the largest outlet glaciers of the Amundsen Sea, and to the bathymetry beneath the floating <span class="hlt">ice</span> in front of their grounding <span class="hlt">zones</span>. Considerable changes have also been observed from the smaller Amundsen <span class="hlt">ice</span> shelves, Crosson and Dotson, which flow to the east and north respectively, between Thwaites Glacier and Getz <span class="hlt">ice</span> shelf, but little is known about their sub-<span class="hlt">ice</span> bathymetry. The Amundsen Sea region is vulnerable to the influence of relatively warm circumpolar deep water encroaching on to the continental shelf. The influence of these waters at the grounding <span class="hlt">zone</span> of the glaciers in the region is dictated by the depth and orientation of bathymetric features of the sea floor. The dominant geological fabric of the region is a NE-SW trending series of ridges and troughs, formed in association with the rifting of the Amundsen Sea region. The bathymetry models from OIB gravity inversions reveal the continuation of the deep (~1500 m) trough of the Kohler Glacier under Crosson <span class="hlt">Ice</span> Shelf. At the eastern end of the trough, at the front of Crosson <span class="hlt">ice</span> shelf, the sea floor rises to an average of ~500 m depth over a broad, 50 km wide region. Further east from here the NE-SW fabric is continued in a previously reported ridge</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70073506','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70073506"><span id="translatedtitle">Mapping the grounding <span class="hlt">zone</span> of Ross <span class="hlt">Ice</span> Shelf using ICESat laser altimetry</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Brunt, Kelly M.; Fricker, Helen A.; Padman, Laurie; Scambos, Ted A.; O'Neel, Shad</p> <p>2010-01-01</p> <p>We use laser altimetry from the <span class="hlt">Ice</span>, Cloud, and land Elevation Satellite (ICESat) to map the grounding <span class="hlt">zone</span> (GZ) of the Ross <span class="hlt">Ice</span> Shelf, Antarctica, at 491 locations where ICESat tracks cross the grounding line (GL). <span class="hlt">Ice</span> flexure in the GZ occurs as the <span class="hlt">ice</span> shelf responds to short-term sea-level changes due primarily to tides. ICESat repeat-track analysis can be used to detect this region of flexure since each repeated pass is acquired at a different tidal phase; the technique provides estimates for both the landward limit of flexure and the point where the <span class="hlt">ice</span> becomes hydrostatically balanced. We find that the ICESat-derived landward limits of tidal flexure are, in many places, offset by several km (and up to ∼60 km) from the GL mapped previously using other satellite methods. We discuss the reasons why different mapping methods lead to different GL estimates, including: instrument limitations; variability in the surface topographic structure of the GZ; and the presence of <span class="hlt">ice</span> plains. We conclude that reliable and accurate mapping of the GL is most likely to be achieved when based on synthesis of several satellite datasets</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16915283','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16915283"><span id="translatedtitle">No signature of clear CO2 <span class="hlt">ice</span> from the 'cryptic' regions in Mars' south <span class="hlt">seasonal</span> polar cap.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Langevin, Yves; Douté, Sylvain; Vincendon, Mathieu; Poulet, François; Bibring, Jean-Pierre; Gondet, Brigitte; Schmitt, Bernard; Forget, F</p> <p>2006-08-17</p> <p>The <span class="hlt">seasonal</span> polar <span class="hlt">ice</span> caps of Mars are composed mainly of CO2 <span class="hlt">ice</span>. A region of low (< 30%) albedo has been observed within the south <span class="hlt">seasonal</span> cap during early to mid-spring. The low temperature of this 'cryptic region' has been attributed to a clear slab of nearly pure CO2 <span class="hlt">ice</span>, with the low albedo resulting from absorption by the underlying surface. Here we report near-infrared imaging spectroscopy of the south <span class="hlt">seasonal</span> cap. The deep and broad CO2 absorption bands that are expected in the near-infrared with a thick transparent slab of CO2 <span class="hlt">ice</span> are not observed. Models of the observed spectra indicate that the low albedo results from extensive dust contamination close to the surface of a CO2 <span class="hlt">ice</span> layer, which could be linked to atmospheric circulation patterns. The strength of the CO2 absorption increases after mid-spring, so part of the dust is either carried away or buried more deeply in the <span class="hlt">ice</span> layer during the CO2 <span class="hlt">ice</span> sublimation process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988JGR....93.6837G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988JGR....93.6837G"><span id="translatedtitle">Satellite and aircraft passive microwave observations during the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> Experiment in 1984</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gloersen, Per; Campbell, William J.</p> <p>1988-06-01</p> <p>During the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> Experiment in the Fram Strait in June-July 1984, a number of aircraft with microwave sensors and the scanning multichannel microwave radiometer (SMMR) on board the Nimbus 7 satellite were used to acquire large-scale and mesoscale <span class="hlt">ice</span>-ocean observations in conjunction with local surface measurements made by experimenters based on helicopter-equipped <span class="hlt">ice</span>-strengthened vessels. An analysis of the data acquired during six flights of one such aircraft, the NASA CV-990 airborne laboratory, is discussed in this paper. Included in the instrument complement of the CV-990 were two passive microwave imagers operating at wavelengths of 0.33 and 1.55 cm and the airborne multichannel microwave radiometer (AMMR) operating at wavelengths of 0.81, 1.4, and 1.7 cm for both horizontal and vertical polarizations. Total and multiyear sea <span class="hlt">ice</span> concentrations calculated from the AMMR data were found to agree with similar calculations using SMMR data. This is the first check of the performance of the SMMR Team <span class="hlt">ice</span> algorithm for near-melting point conditions. The temperature dependence of the multiyear sea <span class="hlt">ice</span> concentration determination near the melting point was found to be the same for both airborne and spacecraft instrument data and to be correlated with presence or absence of clouds. Finally, it was found that a spectral gradient ratio using the data from both the 0.33- and 1.55-cm radiometers provides more reliable distinctions between low total <span class="hlt">ice</span> concentrations and open water storm effects near the <span class="hlt">ice</span> edge than does either singly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4923158','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4923158"><span id="translatedtitle"><span class="hlt">Seasonal</span> Variation of Carbon Metabolism in the Cambial <span class="hlt">Zone</span> of Eucalyptus grandis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Budzinski, Ilara G. F.; Moon, David H.; Lindén, Pernilla; Moritz, Thomas; Labate, Carlos A.</p> <p>2016-01-01</p> <p>Eucalyptus species are the most widely hardwood planted in the world. It is one of the successful examples of commercial forestry plantation in Brazil and other tropical and subtropical countries. The tree is valued for its rapid growth, adaptability and wood quality. Wood formation is the result of cumulative annual activity of the vascular cambium. This cambial activity is generally related to the alternation of cold and warm, and/or dry and rainy <span class="hlt">seasons</span>. Efforts have focused on analysis of cambial <span class="hlt">zone</span> in response to <span class="hlt">seasonal</span> variations in trees from temperate <span class="hlt">zones</span>. However, little is known about the molecular changes triggered by <span class="hlt">seasonal</span> variations in trees from tropical countries. In this work we attempted to establish a global view of <span class="hlt">seasonal</span> alterations in the cambial <span class="hlt">zone</span> of Eucalyptus grandis Hill ex Maiden, emphasizing changes occurring in the carbon metabolism. Using transcripts, proteomics and metabolomics we analyzed the tissues harvested in summer-wet and winter-dry <span class="hlt">seasons</span>. Based on proteomics analysis, 70 proteins that changed in abundance were successfully identified. Transcripts for some of these proteins were analyzed and similar expression patterns were observed. We identified 19 metabolites differentially abundant. Our results suggest a differential reconfiguration of carbon partioning in E. grandis cambial <span class="hlt">zone</span>. During summer, pyruvate is primarily metabolized via ethanolic fermentation, possibly to regenerate NAD+ for glycolytic ATP production and cellular maintenance. However, in winter there seems to be a metabolic change and we found that some sugars were highly abundant. Our results revealed a dynamic change in E. grandis cambial <span class="hlt">zone</span> due to <span class="hlt">seasonality</span> and highlight the importance of glycolysis and ethanolic fermentation for energy generation and maintenance in Eucalyptus, a fast growing tree. PMID:27446160</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27446160','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27446160"><span id="translatedtitle"><span class="hlt">Seasonal</span> Variation of Carbon Metabolism in the Cambial <span class="hlt">Zone</span> of Eucalyptus grandis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Budzinski, Ilara G F; Moon, David H; Lindén, Pernilla; Moritz, Thomas; Labate, Carlos A</p> <p>2016-01-01</p> <p>Eucalyptus species are the most widely hardwood planted in the world. It is one of the successful examples of commercial forestry plantation in Brazil and other tropical and subtropical countries. The tree is valued for its rapid growth, adaptability and wood quality. Wood formation is the result of cumulative annual activity of the vascular cambium. This cambial activity is generally related to the alternation of cold and warm, and/or dry and rainy <span class="hlt">seasons</span>. Efforts have focused on analysis of cambial <span class="hlt">zone</span> in response to <span class="hlt">seasonal</span> variations in trees from temperate <span class="hlt">zones</span>. However, little is known about the molecular changes triggered by <span class="hlt">seasonal</span> variations in trees from tropical countries. In this work we attempted to establish a global view of <span class="hlt">seasonal</span> alterations in the cambial <span class="hlt">zone</span> of Eucalyptus grandis Hill ex Maiden, emphasizing changes occurring in the carbon metabolism. Using transcripts, proteomics and metabolomics we analyzed the tissues harvested in summer-wet and winter-dry <span class="hlt">seasons</span>. Based on proteomics analysis, 70 proteins that changed in abundance were successfully identified. Transcripts for some of these proteins were analyzed and similar expression patterns were observed. We identified 19 metabolites differentially abundant. Our results suggest a differential reconfiguration of carbon partioning in E. grandis cambial <span class="hlt">zone</span>. During summer, pyruvate is primarily metabolized via ethanolic fermentation, possibly to regenerate NAD(+) for glycolytic ATP production and cellular maintenance. However, in winter there seems to be a metabolic change and we found that some sugars were highly abundant. Our results revealed a dynamic change in E. grandis cambial <span class="hlt">zone</span> due to <span class="hlt">seasonality</span> and highlight the importance of glycolysis and ethanolic fermentation for energy generation and maintenance in Eucalyptus, a fast growing tree. PMID:27446160</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015TCry....9.1063P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015TCry....9.1063P"><span id="translatedtitle">Thin-<span class="hlt">ice</span> dynamics and <span class="hlt">ice</span> production in the Storfjorden polynya for winter <span class="hlt">seasons</span> 2002/2003-2013/2014 using MODIS thermal infrared imagery</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Preusser, A.; Willmes, S.; Heinemann, G.; Paul, S.</p> <p>2015-05-01</p> <p>Spatial and temporal characteristics of the Storfjorden polynya, which forms regularly in the proximity of the islands Spitsbergen, Barentsøya and Edgeøya in the Svalbard archipelago under the influence of strong northeasterly winds, have been investigated for the period of 2002/2003 to 2013/2014 using thermal infrared satellite imagery. Thin-<span class="hlt">ice</span> thicknesses were calculated from MODIS <span class="hlt">ice</span>-surface temperatures combined with ECMWF ERA-Interim atmospheric reanalysis data in an energy-balance model. Associated quantities like polynya area and total <span class="hlt">ice</span> production were derived and compared to previous remote sensing and modeling studies. A basic coverage-correction scheme was applied to account for cloud gaps in the daily composites. On average, both polynya area and <span class="hlt">ice</span> production are thereby increased by about 30%. The sea <span class="hlt">ice</span> in the Storfjorden area experiences a late fall freeze-up in several years over the 12-winter period, which becomes most apparent through an increasing frequency of large thin-<span class="hlt">ice</span> areas until the end of December. In the course of an average winter <span class="hlt">season</span>, <span class="hlt">ice</span> thicknesses below 10 cm are dominating within the Storfjorden basin. During the regarded period, the mean polynya area is 4555.7 ± 1542.9 km2. Maximum daily <span class="hlt">ice</span> production rates can reach as high as 26 cm d-1, while the average <span class="hlt">ice</span> production is estimated at 28.3 ± 8.5 km3 per winter and therefore lower than in previous studies. Despite this comparatively short record of 12 winter <span class="hlt">seasons</span>, a significant positive trend of 20.2 km3 per decade could be detected, which originates primarily from a delayed freeze-up in November and December in recent winter <span class="hlt">seasons</span>. This contrasts earlier reports of a slightly negative trend in accumulated <span class="hlt">ice</span> production prior to 2002. Although featuring more pronounced interannual variations between 2004/2005 and 2011/2012, our estimates underline the importance of this relatively small coastal polynya system considering its contribution to the cold</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990042088&hterms=iceland&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Diceland','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990042088&hterms=iceland&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Diceland"><span id="translatedtitle">Analysis of Daily, <span class="hlt">Seasonal</span>, and Interannual Changes in Hofsjokull <span class="hlt">Ice</span> Cap, Iceland, using Satellite Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hall, D. K.; Garvin, J. B.; Williams, R. S., Jr.; Barton, J. S.; Sigurosson, O.; Smith, L. C.</p> <p>1998-01-01</p> <p>Analysis of a time series of European Remote Sensing Satellite (ERS)-1 and -2, RADARSAT ScanSAR synthetic aperture radar (SAR) and Landsat images from 1973 to 1998, shows daily to interannual changes in Hofsjokull, a 923 sq km <span class="hlt">ice</span> cap in central Iceland. A digital elevation model of Hofsjokull was constructed using interferometry, and then SAR backscatter coefficient (d) was plotted with elevation, and air temperature along a transect across the <span class="hlt">ice</span> cap. Most of the a' changes measured along the transect are caused by a change in the state (frozen or thawed) of the surficial snow or <span class="hlt">ice</span> when air temperature rises above or below about -5 to O C. <span class="hlt">Seasonal</span> (sigma)deg patterns are identified in a 4-year time series of 57 ERS-1 and -2 images. In addition, June 1997 ScanSAR images display rapid changes in brightness that are tied closely to daily meteorological events. SAR and Landsat data were also used to measure changes in the areal extent of Hofsjokull, from 1973 to 1997, and to locate (sigma)deg and reflectance boundaries that relate to the glacier facies. Late-summer 1997 (sigma)deg and reflectance boundaries agree and are coincident with the approximate location of the fim line, and the January 1998 position of the equilibrium line as determined from ERS-2 data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011Ocgy...51..295S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011Ocgy...51..295S"><span id="translatedtitle">The inhabitants of the spring <span class="hlt">ice</span>, under-<span class="hlt">ice</span> water, and sediments of the white sea in the estuarine <span class="hlt">zone</span> of the Severnaya Dvina River</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sazhin, A. F.; Sapozhnikov, F. V.; Rat'kova, T. N.; Romanova, N. D.; Shevchenko, V. P.; Filippov, A. S.</p> <p>2011-04-01</p> <p>The data on the supra-<span class="hlt">ice</span> snow, <span class="hlt">ice</span>, under-<span class="hlt">ice</span> water, and benthic algal flora obtained in 2007-2008 by sampling in the estuary of the Severnaya Dvina River are analyzed. The river <span class="hlt">ice</span> and under-<span class="hlt">ice</span> water in the estuarine <span class="hlt">zone</span> and in the channel part of the Severnaya Dvina differed greatly in the algal flora's composition. The fresh water species never exceeded 8.6%, while the <span class="hlt">ice</span> algae composed 90-96% of the total <span class="hlt">ice</span> inhabitants' biomass. In the under-<span class="hlt">ice</span> water, this value did not exceed 58-64%. The bacteria in the <span class="hlt">ice</span> composed not more than 2.5-10% of the total biomass, while, in the under-<span class="hlt">ice</span> water, 36-49%. The shares of ciliates (0.04%) and nematodes (0.005-1.6%) in the total biomass were negligible. In the estuarine <span class="hlt">zone</span>, the <span class="hlt">ice</span> was inhabited mainly by nematodes (78% of the total biomass), while, in the river, their share decreased to 9%. The contribution of bacteria was 15% in Dvina Bay and increased to 61% in the river. The importance of algae in the snow was minor: 7% of the total biomass in the marine <span class="hlt">zone</span> and 30% in the river region. High species diversity of the algal flora in the sandy and sandy-silty littoral grounds was revealed. The values of the total biomass of the bottom algal flora (0.38 g C/m2) were only two to three times lower than the values revealed in similar habitats in the summer. The epipelithic forms (0.15 g C/m2) dominated, being represented by 46 species of algae (49%). The shares of epipsammonic (0.12 g C/m2) and planktonic (0.11 g C/m2) species were almost equal to each other: 25 and 22 species, respectively (27 and 24%).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JMS....95...41S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JMS....95...41S"><span id="translatedtitle">Sea <span class="hlt">ice</span> properties in the Bohai Sea measured by MODIS-Aqua: 2. Study of sea <span class="hlt">ice</span> <span class="hlt">seasonal</span> and interannual variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shi, Wei; Wang, Menghua</p> <p>2012-07-01</p> <p>During the 2009-2010 winter, the Bohai Sea experienced its most severe sea <span class="hlt">ice</span> event in four decades, which caused significant economic losses, affected marine transportation and fishery, and impacted the entire marine ecosystem in the region. Measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite from 2002 to 2010 and surface atmosphere temperature (SAT) data from the National Centers for Environmental Prediction (NCEP) are used to study and quantify the extreme sea <span class="hlt">ice</span> event in the 2009-2010 winter and the interannual variability of the regional sea <span class="hlt">ice</span> properties, as well as the relationship between sea <span class="hlt">ice</span> and the climate variability in the Bohai Sea. The mean sea <span class="hlt">ice</span> reflectance from MODIS-Aqua visible and near-infrared wavelengths are 9.33%, 13.26%, and 12.60% in the months of December 2009, January 2010, and February 2010, respectively, compared with the monthly average sea <span class="hlt">ice</span> reflectance values (from 2002 to 2010) of 9.35%, 11.21%, and 11.41% in the same three winter months. The sea <span class="hlt">ice</span> monthly average coverages are ~ 5427, ~ 27,414, and ~ 21,156 km2 in these three winter months. These values are significantly higher than the averages of monthly sea <span class="hlt">ice</span> coverage of ~ 2735, ~ 11,119, and ~ 10,287 km2 in the Bohai Sea in December, January, and February between 2002 and 2010. Most of the sea <span class="hlt">ice</span> coverage was located in the northern Bohai Sea. Both the intra-<span class="hlt">seasonal</span> and interannual sea <span class="hlt">ice</span> variability in the Bohai Sea is found to be related closely to SAT. The mechanism of anomalous SAT and intense sea <span class="hlt">ice</span> severity are also discussed and attributed to large-scale climate changes due to the variability of the Arctic Oscillation (AO) and Siberian High (SH).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BGD....12.1975M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BGD....12.1975M"><span id="translatedtitle"><span class="hlt">Seasonal</span> dynamics of organic carbon and metals in thermokarst lakes from the discontinuous permafrost <span class="hlt">zone</span> of western Siberia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Manasypov, R. M.; Vorobyev, S. N.; Loiko, S. V.; Kritzkov, I. V.; Shirokova, L. S.; Shevchenko, V. P.; Kirpotin, S. N.; Kulizhsky, S. P.; Kolesnichenko, L. G.; Zemtzov, V. A.; Sinkinov, V. V.; Pokrovsky, O. S.</p> <p>2015-01-01</p> <p>Western Siberia's thermokarst (thaw) lakes extend over a territory spanning over a million km2; they are highly dynamic hydrochemical systems that receive chemical elements from the atmosphere and surrounding peat soil and vegetation, and exchange greenhouse gases with the atmosphere, delivering dissolved carbon and metals to adjacent hydrological systems. This work describes the chemical composition of ~ 130 thermokarst lakes of the size range from a few m2 to several km2, located in the discontinuous permafrost <span class="hlt">zone</span>. Lakes were sampled during spring floods, just after the <span class="hlt">ice</span> break (early June), the end of summer (August), the beginning of <span class="hlt">ice</span> formation (October) and during the full freezing <span class="hlt">season</span> in winter (February). Dissolved organic carbon (DOC) and the major and trace elements do not appreciably change their concentration with the lake size increase above 1000 m2 during all <span class="hlt">seasons</span>. On the annual scale, the majority of dissolved elements including organic carbon increase their concentration from 30 to 500%, with a statistically significant (p < 0.05) trend from spring to winter. The maximal increase in trace element (TE) concentration occurred between spring and summer and autumn and winter. The <span class="hlt">ice</span> formation in October included several stages: first, surface layer freezing followed by crack (fissure) formation with unfrozen water from the deeper layers spreading over the <span class="hlt">ice</span> surface. This water was subsequently frozen and formed layered <span class="hlt">ice</span> rich in organic matter. As a result, the DOC and metal concentrations were the highest at the beginning of the <span class="hlt">ice</span> column and decreased from the surface to the depth. A number of elements demonstrated the accumulation, by more than a factor of 2, in the surface (0-20 cm) of the <span class="hlt">ice</span> column relative to the rest of the <span class="hlt">ice</span> core: Mn, Fe, Ni, Cu, Zn, As, Ba and Pb. The main consequences of discovered freeze-driven solute concentrations in thermokarst lake waters are enhanced colloidal coagulation and the removal of dissolved</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C51B0723C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C51B0723C"><span id="translatedtitle">Initial Steps Toward a Hydrologic "Watershed" Model for the Ablation <span class="hlt">Zone</span> of the Greenland <span class="hlt">Ice</span> Sheet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cooper, M. G.; Smith, L. C.; Rennermalm, A. K.; Pitcher, L. H.; Overstreet, B. T.; Chu, V. W.; Ryan, J.; Yang, K.</p> <p>2015-12-01</p> <p>Surface meltwater production on the Greenland <span class="hlt">Ice</span> Sheet (GrIS) is a well-documented phenomenon but we lack understanding of the physical mechanisms that control the production, transport, and fate of the meltwater. To address this, we present initial steps toward the development of a novel hydrologic model for supraglacial streamflow on the GrIS. <span class="hlt">Ice</span> ablation and surface meteorology were measured during a 6-day field campaign in a 112 km2 ablation <span class="hlt">zone</span> of southwest Greenland. We modeled ablation using SnowModel, an energy balance snow- and <span class="hlt">ice</span>-ablation model. The required model inputs included standard surface meteorology and a digital elevation model (DEM), and the model outputs include all components of the energy balance and surface meltwater production for each grid cell in the <span class="hlt">ice</span>-sheet watershed. Our next steps toward developing a complete hydrologic model for supraglacial streamflow in the ablation <span class="hlt">zone</span> of the GrIS include the application of the meltwater-routing model HydroFlow to compare with in-situ measurements of supraglacial river discharge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E1894T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E1894T"><span id="translatedtitle">Meso- and submesoscale structures in marginal <span class="hlt">ice</span> <span class="hlt">zone</span> in Arctic ocean using Sentinel-1 data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tarasenko, Anastasiia</p> <p>2016-07-01</p> <p>A marginal sea <span class="hlt">ice</span> <span class="hlt">zone</span> is a region where ocean currents interact with the sea <span class="hlt">ice</span>. Recently freezed small sea <span class="hlt">ice</span> particles (frazil) can be used as a passive tracer for the ocean surface dynamics studies. Sentinel-1 SAR images with a high spatial resolution (40 or 25 m) permit to exploit this approach of "frazil as surface current's passive tracer". A preliminary research on meso- and submesoscale structures in marginal sea <span class="hlt">ice</span> <span class="hlt">zone</span> was carried out using Sentinel-1 SAR data. A new dataset of mesoscale structures was created for Eastern Greenland, Barents and Kara seas for 2014-2015. The raw data was processed with SNAP (Sentinel application Platform designed by ESA). A classical method of maximum cross-correlation was tested together with a method developed based on (Kudriavtsev et al, 2014) for eddy-like structures detection. References: Kudryavtsev, Vladimir, I. Kozlov, Bertrand Chapron, and J. A. Johannessen. "Quad-polarization SAR features of ocean currents." Journal of Geophysical Research: Oceans 119, no. 9 (2014): 6046-6065.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title46-vol2/pdf/CFR-2011-title46-vol2-sec42-30-5.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title46-vol2/pdf/CFR-2011-title46-vol2-sec42-30-5.pdf"><span id="translatedtitle">46 CFR 42.30-5 - Northern Winter <span class="hlt">Seasonal</span> <span class="hlt">Zones</span> and area.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-10-01</p> <p>... 46 Shipping 2 2011-10-01 2011-10-01 false Northern Winter <span class="hlt">Seasonal</span> <span class="hlt">Zones</span> and area. 42.30-5 Section 42.30-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES DOMESTIC AND... extremity of Cape Kril'on: thence the rhumb line to Wakkanai, Hokkaido, Japan; thence the east and...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title36-vol1/pdf/CFR-2013-title36-vol1-sec13-912.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title36-vol1/pdf/CFR-2013-title36-vol1-sec13-912.pdf"><span id="translatedtitle">36 CFR 13.912 - Kantishna area summer <span class="hlt">season</span> firearm safety <span class="hlt">zone</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Kantishna area summer <span class="hlt">season</span> firearm safety <span class="hlt">zone</span>. 13.912 Section 13.912 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Denali National Park...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2013-06-27/pdf/2013-15496.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2013-06-27/pdf/2013-15496.pdf"><span id="translatedtitle">78 FR 38584 - Safety <span class="hlt">Zone</span>; San Diego Symphony Summer POPS Fireworks 2013 <span class="hlt">Season</span>, San Diego, CA</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2013-06-27</p> <p>... FR Federal Register NPRM Notice of Proposed Rulemaking A. Regulatory History and Information The... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety <span class="hlt">Zone</span>; San Diego Symphony Summer POPS Fireworks 2013 <span class="hlt">Season</span>, San Diego, CA AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ClDy...37.2107S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ClDy...37.2107S"><span id="translatedtitle">Snow precipitation at four <span class="hlt">ice</span> core sites in East Antarctica: provenance, <span class="hlt">seasonality</span> and blocking factors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scarchilli, Claudio; Frezzotti, Massimo; Ruti, Paolo Michele</p> <p>2011-11-01</p> <p>Snow precipitation is the primary mass input to the Antarctic <span class="hlt">ice</span> sheet and is one of the most direct climatic indicators, with important implications for paleoclimatic reconstruction from <span class="hlt">ice</span> cores. Provenance of precipitation and the dynamic conditions that force these precipitation events at four deep <span class="hlt">ice</span> core sites (Dome C, Law Dome, Talos Dome, and Taylor Dome) in East Antarctica were analysed with air mass back trajectories calculated using the Lagrangian model and the mean composite data for precipitation, geopotential height and wind speed field data from the European Centre for Medium Range Weather Forecast from 1980 to 2001. On an annual basis, back trajectories showed that the Atlantic-Indian and Ross-Pacific Oceans were the main provenances of precipitation in Wilkes Land (80%) and Victoria Land (40%), respectively, whereas the greatest influence of the <span class="hlt">ice</span> sheet was on the interior near the Vostok site (80%) and in the Southwest Ross Sea (50%), an effect that decreased towards the coast and along the Antarctic slope. Victoria Land received snowfall atypically with respect to other Antarctica areas in terms of pathway (eastern instead of western), <span class="hlt">seasonality</span> (summer instead of winter) and velocity (old air age). Geopotential height patterns at 500 hPa at low (>10 days) and high (2-6 days) frequencies during snowfall cycles at two core sites showed large positive anomalies at low frequencies developing in the Tasman Sea-Eastern Indian Ocean at higher latitudes (60-70°S) than normal. This could be considered part of an atmospheric blocking event, with transient eddies acting to decelerate westerlies in a split region area and accelerate the flow on the flanks of the low-frequency positive anomalies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.C51B1048K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.C51B1048K"><span id="translatedtitle">Geochemical Characteristics And <span class="hlt">Zones</span> Of Surface Snow On East Antarctic <span class="hlt">Ice</span> sheet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kang, J.</p> <p>2004-12-01</p> <p>Geochemical characteristics and <span class="hlt">zones</span> of surface snow on east Antarctic <span class="hlt">Ice</span> Sheet Jiancheng KANG1,4, Leibao LIU1, Dahe QIN2, Dali WANG1, Jiahong WEN1, Dejun TAN1, Zhongqin LI2, Jun LI3 & Xiaowei ZHANG1,4 1 Polar Research Institute of China, Shanghai 200129, China; 2 Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; 3 Australian Antarctic Division and Antarctic Climate and Ecosystems CRC, Private Bag 80 Hobart, Tasmania, 7001, Australia; 4 Geography Department of Lanzhou University, Lanzhou 730000, China Correspondence should be addressed to Jiancheng KANG (email: kangjc@sh163.net, kangjc@126.com ) Abstract The surface-snow geochemical characteristics are discussed on the East Antarctic <span class="hlt">Ice</span> Sheet, depending on the stable isotopes ratios of oxygen and hydrogen, concentration of impurities (soluble-ions and insoluble micro-particle) in surface snow collected on the <span class="hlt">ice</span> sheet. The purpose is to study geochemical <span class="hlt">zones</span> on the East Antarctic <span class="hlt">Ice</span> Sheet and to research sources and transportation route of the water vapor and the impurities in surface snow. It has been found that the ratio coefficients, as S1, d1 in the equation ƒOD = S1ƒO18O + d1, are changed near the elevation 2000m on the <span class="hlt">ice</span> sheet. The weight ratio of Cl-/Na+ at the area below the elevation of 2000m is close to the ratio in the sea salt; but it is about 2 times that of the sea salt, at the inland area up to the elevation of 2000m. The concentrations of non-sea-salt Ca2+ ion (nssCa2+) and fine-particle increase at the interior up to the elevation 2000m. At the region below the elevation of 2000m, the impurity concentration is decreasing with the elevation increasing. Near coastal region, the surface snow has a high concentration of impurity, where the elevation is below 800m. Combining the translating processes of water-vapor and impurities, it suggests that the region up to the elevation 2000m is affected by large</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PIAHS.374..143F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PIAHS.374..143F"><span id="translatedtitle">A snow and <span class="hlt">ice</span> melt <span class="hlt">seasonal</span> prediction modelling system for Alpine reservoirs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Förster, Kristian; Oesterle, Felix; Hanzer, Florian; Schöber, Johannes; Huttenlau, Matthias; Strasser, Ulrich</p> <p>2016-10-01</p> <p>The timing and the volume of snow and <span class="hlt">ice</span> melt in Alpine catchments are crucial for management operations of reservoirs and hydropower generation. Moreover, a sustainable reservoir operation through reservoir storage and flow control as part of flood risk management is important for downstream communities. Forecast systems typically provide predictions for a few days in advance. Reservoir operators would benefit if lead times could be extended in order to optimise the reservoir management. Current <span class="hlt">seasonal</span> prediction products such as the NCEP (National Centers for Environmental Prediction) Climate Forecast System version 2 (CFSv2) enable <span class="hlt">seasonal</span> forecasts up to nine months in advance, with of course decreasing accuracy as lead-time increases. We present a coupled <span class="hlt">seasonal</span> prediction modelling system that runs at monthly time steps for a small catchment in the Austrian Alps (Gepatschalm). Meteorological forecasts are obtained from the CFSv2 model. Subsequently, these data are downscaled to the Alpine Water balance And Runoff Estimation model AWARE running at monthly time step. Initial conditions are obtained using the physically based, hydro-climatological snow model AMUNDSEN that predicts hourly fields of snow water equivalent and snowmelt at a regular grid with 50 m spacing. Reservoir inflow is calculated taking into account various runs of the CFSv2 model. These simulations are compared with observed inflow volumes for the melting and accumulation period 2015.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1817421J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1817421J"><span id="translatedtitle">Influence of <span class="hlt">ice</span> sheet bed morphology on spatial and <span class="hlt">seasonal</span> patterns of <span class="hlt">ice</span> flow in Greenland: preliminary results from an automated method for interpreting high resolution <span class="hlt">ice</span> velocity data derived from Landsat imagery.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jones, Andrew H.; Swift, Darrel A.; Livingstone, Stephen J.</p> <p>2016-04-01</p> <p><span class="hlt">Ice</span> sheet bed morphology affects <span class="hlt">ice</span> flow rates and patterns by topographically directing and resisting <span class="hlt">ice</span> flow and by modulating rates of basal sliding. Notably, reverse bedslopes are anticipated to modulate basal sliding rates and mechanisms through their control on subglacial drainage system morphology and efficiency. In <span class="hlt">ice</span> sheet contexts, understanding of the significance of these controls, their relative importance and ubiquity, remains weak. We aim to use contemporary remote sensing data products that provide high spatial and temporal resolution <span class="hlt">ice</span> velocity and bed data for the Greenland <span class="hlt">ice</span> sheet to attempt a comprehensive and systematic analysis of spatial and <span class="hlt">seasonal</span> variation in flow behaviour and its links to bed morphology. Here we present an automated method for high resolution 4-dimensional analysis of a large archive dataset (Rosenau et al, 2015) of Landsat-derived <span class="hlt">ice</span> velocity that enables the extraction of velocity data along a large number of longitudinal flowlines for individual glacier catchments and the analysis of along-flow velocity patterns. Analysis can be undertaken on individual flowlines, or adjacent flowlines can be custom aggregated both spatially and temporarily to investigate factors such as intra-annual or inter-annual <span class="hlt">seasonal</span> patterns. We present initial analyses of <span class="hlt">seasonal</span> velocity changes at a sample of glacier catchments and their relationship to glacier bed characteristics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1617004Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1617004Z"><span id="translatedtitle">Local effects of <span class="hlt">ice</span> floes and leads on skin sea surface temperature, mixing and gas transfer in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zappa, Christopher; Brumer, Sophia; Brown, Scott; LeBel, Deborah; McGillis, Wade; Schlosser, Peter; Loose, Brice</p> <p>2014-05-01</p> <p>Recent years have seen extreme changes in the Arctic. Marginal <span class="hlt">ice</span> <span class="hlt">zones</span> (MIZ), or areas where the "<span class="hlt">ice</span>-albedo feedback" driven by solar warming is highest and <span class="hlt">ice</span> melt is extensive, may provide insights into the extent of these changes. Furthermore, MIZ play a central role in setting the air-sea CO2 balance making them a critical component of the global carbon cycle. Incomplete understanding of how the sea-<span class="hlt">ice</span> modulates gas fluxes renders it difficult to estimate the carbon budget in MIZ. Here, we investigate the turbulent mechanisms driving gas exchange in leads, polynyas and in the presence of <span class="hlt">ice</span> floes using both field and laboratory measurements. Here, we present measurements of visible and IR imagery of melting <span class="hlt">ice</span> floes in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> north of Oliktok Point AK in the Beaufort Sea made during the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> Ocean and <span class="hlt">Ice</span> Observations and Processes EXperiment (MIZOPEX) in July-August 2013. The visible and IR imagery were taken from the unmanned airborne vehicle (UAV) ScanEagle. The visible imagery clearly defines the scale of the <span class="hlt">ice</span> floes. The IR imagery show distinct cooling of the skin sea surface temperature (SST) as well as an intricate circulation and mixing pattern that depends on the surface current, wind speed, and near-surface vertical temperature/salinity structure. Individual <span class="hlt">ice</span> floes develop turbulent wakes as they drift and cause transient mixing of an influx of colder surface (fresh) melt water. We capture a melting and mixing event that explains the changing pattern observed in skin SST and is substantiated using laboratory experiments. The Gas Transfer through Polar Sea <span class="hlt">Ice</span> experiment was performed at the US Army Cold Regions Research and Engineering Laboratory (Hanover, NH) under varying <span class="hlt">ice</span> coverage, winds speed, fetch and currents. Supporting measurements were made of air and water temperature, humidity, salinity and wave height. Air-side profiling provided momentum, heat, and CO2 fluxes. Transfer velocities are also</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993DSRI...40..311G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993DSRI...40..311G&link_type=ABSTRACT"><span id="translatedtitle">Winter plankton assemblage in the <span class="hlt">ice</span> edge <span class="hlt">zone</span> of the Weddell and scotia seas: composition, biomass and spatial distributions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garrison, David L.; Buck, Kurt R.; Gowing, Marcia M.</p> <p>1993-02-01</p> <p>As part of the Antarctic Marine Ecosystem Research in the <span class="hlt">Ice</span> Edge <span class="hlt">Zone</span> (AMERIEZ) program, we examined the biomass and distribution of phytoplankton and protozooplankton at an advancing <span class="hlt">ice</span> edge in the Weddell and Scotia Seas during the early austral winter. The advance of <span class="hlt">ice</span> cover, local melting of sea <span class="hlt">ice</span> and advection of water masses, possibly from lower latitude regions, were the main sources of variability in the physical regime of the <span class="hlt">ice</span>-edge <span class="hlt">zone</span>. Analysis of the plankton assemblage showed phytoplankton biomass (PPC) in the upper 100 m ranging from 100 to 272 mg C m -2 and protozooplankton biomass (PZC) ranging from 177 to 410 mg C m -2. Autotrophic dinoflagellates dominated phytoplankton stocks, followed by other autotrophic nanoflagellates and diatoms in decreasing biomass. Heterotrophic flagellates dominated protozooplankton biomass followed by ciliates and sarcodines. The biomass of major groups comprising the planktonic assemblage was similar at most stations with the exception of one station where diatoms predominated. Integrated PPC and PZC showed no relationship to water column stability. Integrated autotrophic flagellate biomass was higher at open water stations than at <span class="hlt">ice</span>-covered stations, but none of the other integrated group biomasses showed variations that could be related to <span class="hlt">ice</span> cover or water mass characteristics. Analysis of discrete-depth samples indicated that all groups (except the sarcodines) showed near surface maxima, that total PPC, diatoms and autotrophic flagellates showed higher biomasses at <span class="hlt">ice</span>-edge and open water stations than at <span class="hlt">ice</span>-covered stations and that none of the heterotrophs showed variations related to <span class="hlt">ice</span> cover. Some groups, however, showed differences that could be related to water mass characteristics, but this was less evident than was the effect of depth or <span class="hlt">ice</span> cover. Comparison of species assemblages of diatoms and choanoflagellates among water column stations indicated variations that could be related to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20070034942&hterms=solar+energy&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dsolar%2Benergy','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20070034942&hterms=solar+energy&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dsolar%2Benergy"><span id="translatedtitle"><span class="hlt">Seasonal</span> Evolution and Interannual Variability of the Local Solar Energy Absorbed by the Arctic Sea <span class="hlt">Ice</span>-Ocean System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Perovich, Donald K.; Nghiem, Son V.; Markus, Thorsten; Schwieger, Axel</p> <p>2007-01-01</p> <p>The melt <span class="hlt">season</span> of the Arctic sea <span class="hlt">ice</span> cover is greatly affected by the partitioning of the incident solar radiation between reflection to the atmosphere and absorption in the <span class="hlt">ice</span> and ocean. This partitioning exhibits a strong <span class="hlt">seasonal</span> cycle and significant interannual variability. Data in the period 1998, 2000-2004 were analyzed in this study. Observations made during the 1997-1998 SHEBA (Surface HEat Budget of the Arctic Ocean) field experiment showed a strong <span class="hlt">seasonal</span> dependence of the partitioning, dominated by a five-phase albedo evolution. QuikSCAT scatterometer data from the SHEBA region in 1999-2004 were used to further investigate solar partitioning in summer. The time series of scatterometer data were used to determine the onset of melt and the beginning of freezeup. This information was combined with SSM/I-derived <span class="hlt">ice</span> concentration, TOVS-based estimates of incident solar irradiance, and SHEBA results to estimate the amount of solar energy absorbed in the <span class="hlt">ice</span>-ocean system for these years. The average total solar energy absorbed in the <span class="hlt">ice</span>-ocean system from April through September was 900 MJ m(sup -2). There was considerable interannual variability, with a range of 826 to 1044 MJ m(sup -2). The total amount of solar energy absorbed by the <span class="hlt">ice</span> and ocean was strongly related to the date of melt onset, but only weakly related to the total duration of the melt <span class="hlt">season</span> or the onset of freezeup. The timing of melt onset is significant because the incident solar energy is large and a change at this time propagates through the entire melt <span class="hlt">season</span>, affecting the albedo every day throughout melt and freezeup.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16903279','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16903279"><span id="translatedtitle"><span class="hlt">Seasonal</span> variability and long term trends of chlorofluorocarbon mixing ratios in the unsaturated <span class="hlt">zone</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Santella, Nicholas; Schlosser, Peter; Smethie, William M; Ho, David T; Stute, Martin</p> <p>2006-07-15</p> <p>To investigate processes that might affect chlorofluorocarbon (CFC) mixing ratios at the water table, a time series was obtained of unsaturated <span class="hlt">zone</span> soil gas CFCs to depths of ca. 4 m at a site near New York City (NYC). Observed CFC 11, 12, and 113 mixing ratios were lower in winter than expected from either a local, high-resolution time series or remote atmospheric mixing ratios. A diffusion model, which includes <span class="hlt">seasonal</span> changes in soil temperature, moisture, and CFC solubility, reproduces to first order the observed soil gas mixing ratios for CFC 11 and 12. Underestimation by the model of the <span class="hlt">seasonal</span> cycle of CFC 11 points to changing levels of sorption to soils due to <span class="hlt">seasonal</span> changes in temperature as an additional cause of the cycle seen in CFC 11 mixing ratios in soil air. In the case of spring recharge, low CFC mixing ratios in soil air caused by increased solubility may result in low CFC 11 concentrations in groundwater and, when dating groundwater recharged before the 1990s with CFCs, older apparent ages by up to 4 years. Attempts to observe average atmospheric CFC levels from soil gas are also significantly hindered by these <span class="hlt">seasonal</span> fluctuations. Our results indicate the importance of considering <span class="hlt">seasonal</span> changes in soil temperature when making precise observations of even very moderately soluble gases in the unsaturated <span class="hlt">zone</span> and shallow groundwater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3982526','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3982526"><span id="translatedtitle">Dissolved and particulate trace metal micronutrients under the McMurdo Sound <span class="hlt">seasonal</span> sea <span class="hlt">ice</span>: basal sea <span class="hlt">ice</span> communities as a capacitor for iron</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Noble, Abigail E.; Moran, Dawn M.; Allen, Andrew E.; Saito, Mak A.</p> <p>2013-01-01</p> <p>Dissolved and particulate metal concentrations are reported from three sites beneath and at the base of the McMurdo Sound <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> in the Ross Sea of Antarctica. This dataset provided insight into Co and Mn biogeochemistry, supporting a previous hypothesis for water column mixing occurring faster than scavenging. Three observations support this: first, Mn-containing particles with Mn/Al ratios in excess of the sediment were present in the water column, implying the presence of bacterial Mn-oxidation processes. Second, dissolved and labile Co were uniform with depth beneath the sea <span class="hlt">ice</span> after the winter <span class="hlt">season</span>. Third, dissolved Co:PO3−4 ratios were consistent with previously observed Ross Sea stoichiometry, implying that over-winter scavenging was slow relative to mixing. Abundant dissolved Fe and Mn were consistent with a winter reserve concept, and particulate Al, Fe, Mn, and Co covaried, implying that these metals behaved similarly. Elevated particulate metals were observed in proximity to the nearby Islands, with particulate Fe/Al ratios similar to that of nearby sediment, consistent with a sediment resuspension source. Dissolved and particulate metals were elevated at the shallowest depths (particularly Fe) with elevated particulate P/Al and Fe/Al ratios in excess of sediments, demonstrating a sea <span class="hlt">ice</span> biomass source. The sea <span class="hlt">ice</span> biomass was extremely dense (chl a >9500 μg/L) and contained high abundances of particulate metals with elevated metal/Al ratios. A hypothesis for <span class="hlt">seasonal</span> accumulation of bioactive metals at the base of the McMurdo Sound sea <span class="hlt">ice</span> by the basal algal community is presented, analogous to a capacitor that accumulates iron during the spring and early summer. The release and transport of particulate metals accumulated at the base of the sea <span class="hlt">ice</span> by sloughing is discussed as a potentially important mechanism in providing iron nutrition during polynya phytoplankton bloom formation and could be examined in future oceanographic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013FrCh....1...25N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013FrCh....1...25N"><span id="translatedtitle">Dissolved and particulate trace metal micronutrients under the McMurdo Sound <span class="hlt">seasonal</span> sea <span class="hlt">ice</span>: basal sea <span class="hlt">ice</span> communities as a capacitor for iron</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Noble, Abigail; Saito, Mak; Moran, Dawn; Allen, Andrew</p> <p>2013-10-01</p> <p>Dissolved and particulate metal concentrations are reported from three sites beneath and at the base of the McMurdo Sound <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> in the Ross Sea of Antarctica. This dataset provided insight into Co and Mn biogeochemistry, supporting a previous hypothesis for water column mixing occurring faster than scavenging. Three observations support this: first, Mn-containing particles with Mn/Al ratios in excess of the sediment were present in the water column, implying the presence of bacterial Mn-oxidation processes. Second, dissolved and labile Co were uniform with depth beneath the sea <span class="hlt">ice</span> after the winter <span class="hlt">season</span>. Third, dissolved Co:PO43- ratios were consistent with previously observed Ross Sea stoichiometry, implying that over-winter scavenging was slow relative to mixing. Abundant dissolved Fe and Mn were consistent with a winter reserve concept, and particulate Al, Fe, Mn, and Co covaried, implying that these metals behaved similarly. Elevated particulate metals were observed in proximity to the nearby Islands, with particulate Fe/Al ratios similar to that of nearby sediment, consistent with a sediment resuspension source. Dissolved and particulate metals were elevated at the shallowest depths (particularly Fe) with elevated particulate P/Al and Fe/Al ratios in excess of sediments, demonstrating a sea <span class="hlt">ice</span> biomass source. The sea <span class="hlt">ice</span> biomass was extremely dense (chl a >9500 μg/L) and contained high abundances of particulate metals with elevated metal/Al ratios. A hypothesis for <span class="hlt">seasonal</span> accumulation of bioactive metals at the base of the McMurdo Sound sea <span class="hlt">ice</span> by the basal algal community is presented, analogous to a capacitor that accumulates iron during the spring and early summer. The release and transport of particulate metals accumulated at the base of the sea <span class="hlt">ice</span> by sloughing is discussed as a potentially important mechanism in providing iron nutrition during polynya phytoplankton bloom formation and could be examined in future oceanographic expeditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010037377','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010037377"><span id="translatedtitle">A 21-Year Record of Arctic Sea <span class="hlt">Ice</span> Extents and Their Regional, <span class="hlt">Seasonal</span>, and Monthly Variability and Trends</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parkinson, Claire L.; Cavalieri, Donald J.; Zukor, Dorothy J. (Technical Monitor)</p> <p>2001-01-01</p> <p>Satellite passive-microwave data have been used to calculate sea <span class="hlt">ice</span> extents over the period 1979-1999 for the north polar sea <span class="hlt">ice</span> cover as a whole and for each of nine regions. Over this 21-year time period, the trend in yearly average <span class="hlt">ice</span> extents for the <span class="hlt">ice</span> cover as a whole is -32,900 +/- 6,100 sq km/yr (-2.7 +/- 0.5 %/decade), indicating a reduction in sea <span class="hlt">ice</span> coverage that has decelerated from the earlier reported value of -34,000 +/- 8,300 sq km/yr (-2.8 +/- 0.7 %/decade) for the period 1979-1996. Regionally, the reductions are greatest in the Arctic Ocean, the Kara and Barents Seas, and the Seas of Okhotsk and Japan, whereas <span class="hlt">seasonally</span>, the reductions are greatest in summer, for which <span class="hlt">season</span> the 1979-1999 trend in <span class="hlt">ice</span> extents is -41,600 +/- 12,900 sq km/ yr (-4.9 +/- 1.5 %/decade). On a monthly basis, the reductions are greatest in July and September for the north polar <span class="hlt">ice</span> cover as a whole, in September for the Arctic Ocean, in June and July for the Kara and Barents Seas, and in April for the Seas of Okhotsk and Japan. Only two of the nine regions show overall <span class="hlt">ice</span> extent increases, those being the Bering Sea and the Gulf of St. Lawrence.For neither of these two regions is the increase statistically significant, whereas the 1079 - 1999 <span class="hlt">ice</span> extent decreases are statistically significant at the 99% confidence level for the north polar region as a whole, the Arctic Ocean, the Seas of Okhotsk and Japan, and Hudson Bay.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012Geomo.161...73G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012Geomo.161...73G"><span id="translatedtitle">Transverse, supraglacially derived crevasse infillings in a Pleistocene <span class="hlt">ice</span>-sheet margin <span class="hlt">zone</span> (eastern Poland): Genesis and sedimentary record</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Godlewska, Anna; Terpiłowski, Sławomir</p> <p>2012-08-01</p> <p>The so-called 'crevasse infillings' in the marginal <span class="hlt">zone</span> of the Saalian <span class="hlt">ice</span> sheet in eastern Poland are atypical relief forms for lowlands glaciated in the Pleistocene. They are located on a high of the Cretaceous/Palaeogene substratum and form isolated ridges arranged in trains parallel to the former <span class="hlt">ice</span>-sheet margin, i.e., transverse to the movement of the <span class="hlt">ice</span> sheet. The sedimentary succession of the crevasse infillings consists mainly of undeformed glaciodeltaic deposits. We propose a model of the crevasse infilling development in three phases against the background of <span class="hlt">ice</span> mass dynamics: 1) <span class="hlt">ice</span>-sheet advance over a high of the substratum — compressive <span class="hlt">ice</span> flow that bumped against the high's slope and enrichment of the <span class="hlt">ice</span> with debris; 2) an overriding of the substratum high by <span class="hlt">ice</span> masses — a tensional <span class="hlt">ice</span>-flow regime resulted in significant crevassing; and 3) <span class="hlt">ice</span> mass stagnation — low energy, supraglacial deltaic sedimentation in isolated ponds between disintegrated <span class="hlt">ice</span> blocks under frozen bed conditions. Considering this genesis, we suggest classifying these forms as kames instead of crevasse infillings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70025199','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70025199"><span id="translatedtitle"><span class="hlt">Seasonal</span> deuterium excess in a Tien Shan <span class="hlt">ice</span> core: Influence of moisture transport and recycling in Central Asia</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kreutz, K.J.; Wake, C.P.; Aizen, V.B.; DeWayne, Cecil L.; Synal, H.-A.</p> <p>2003-01-01</p> <p>Stable water isotope (??18O, ??D) data from a high elevation (5100 masl) <span class="hlt">ice</span> core recovered from the Tien Shan Mountains, Kyrgyzstan, display a <span class="hlt">seasonal</span> cycle in deuterium excess (d = ??D - 8*??18O) related to changes in the regional hydrologic cycle during 1994-2000. While there is a strong correlation (r2 = 0.98) between ??18O and ??D in the <span class="hlt">ice</span> core samples, the regression slope (6.9) and mean d value (23.0) are significantly different than the global meteoric water line values. The resulting time-series <span class="hlt">ice</span> core d profile contains distinct winter maxima and summer minima, with a yearly d amplitude of ???15-20???. Local-scale processes that may affect d values preserved in the <span class="hlt">ice</span> core are not consistent with the observed <span class="hlt">seasonal</span> variability. Data from Central Asian monitoring sites in the Global Network of Isotopes in Precipitation (GNIP) have similar <span class="hlt">seasonal</span> d changes. We suggest that regional-scale hydrological conditions, including <span class="hlt">seasonal</span> changes in moisture source, transport, and recycling in the Caspian/Aral Sea region, are responsible for the observed spatial and temporal d variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160001390','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160001390"><span id="translatedtitle">Revisiting the Potential of Melt Pond Fraction as a Predictor for the <span class="hlt">Seasonal</span> Arctic Sea <span class="hlt">Ice</span> Extent Minimum</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Liu, Jiping; Song, Mirong; Horton, Radley M.; Hu, Yongyun</p> <p>2015-01-01</p> <p>The rapid change in Arctic sea <span class="hlt">ice</span> in recent decades has led to a rising demand for <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> prediction. A recent modeling study that employed a prognostic melt pond model in a stand-alone sea <span class="hlt">ice</span> model found that September Arctic sea <span class="hlt">ice</span> extent can be accurately predicted from the melt pond fraction in May. Here we show that satellite observations show no evidence of predictive skill in May. However, we find that a significantly strong relationship (high predictability) first emerges as the melt pond fraction is integrated from early May to late June, with a persistent strong relationship only occurring after late July. Our results highlight that late spring to mid summer melt pond information is required to improve the prediction skill of the <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> minimum. Furthermore, satellite observations indicate a much higher percentage of melt pond formation in May than does the aforementioned model simulation, which points to the need to reconcile model simulations and observations, in order to better understand key mechanisms of melt pond formation and evolution and their influence on sea <span class="hlt">ice</span> state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRC..11611032M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRC..11611032M"><span id="translatedtitle">The <span class="hlt">seasonal</span> appearance of <span class="hlt">ice</span> shelf water in coastal Antarctica and its effect on sea <span class="hlt">ice</span> growth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mahoney, Andrew R.; Gough, Alexander J.; Langhorne, Patricia J.; Robinson, Natalie J.; Stevens, Craig L.; Williams, Michael M. J.; Haskell, Timothy G.</p> <p>2011-11-01</p> <p>In this paper we report measurements from the first year-round mooring underneath sea <span class="hlt">ice</span> in McMurdo Sound, Antarctica, which we combine with full-depth ocean profiles to identify the incremental appearance of potentially supercooled <span class="hlt">ice</span> shelf water (ISW). We investigate the effects of ISW on sea <span class="hlt">ice</span> using observations of sea <span class="hlt">ice</span> growth and crystal structure together with under-<span class="hlt">ice</span> photography. We show that the appearance of ISW at the surface leads to a disruption in the columnar texture of the sea <span class="hlt">ice</span>, but that persistent growth enhancement occurs only once the entire water column has cooled to the surface freezing point. In doing so, we demonstrate the possibility of inferring the presence of ISW beneath sea <span class="hlt">ice</span> through crystallographic analysis of cores. These findings will be useful for both modeling and observing the extent of ISW-enhanced <span class="hlt">ice</span> growth. In addition, we found that the local growth of first-year landfast sea <span class="hlt">ice</span> only accounted for half of the observed increase in salinity over the water column, which indicates that polynyas are responsible for approximately half of the salt flux into McMurdo Sound.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830061623&hterms=Ice+Age&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2528Ice%2BAge%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830061623&hterms=Ice+Age&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2528Ice%2BAge%2529"><span id="translatedtitle">Simple energy balance model resolving the <span class="hlt">seasons</span> and the continents - Application to the astronomical theory of the <span class="hlt">ice</span> ages</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>North, G. R.; Short, D. A.; Mengel, J. G.</p> <p>1983-01-01</p> <p>An analysis is undertaken of the properties of a one-level <span class="hlt">seasonal</span> energy balance climate model having explicit, two-dimensional land-sea geography, where land and sea surfaces are strictly distinguished by the local thermal inertia employed and transport is governed by a smooth, latitude-dependent diffusion mechanism. Solutions of the <span class="hlt">seasonal</span> cycle for the cases of both <span class="hlt">ice</span> feedback exclusion and inclusion yield good agreements with real data, using minimal turning of the adjustable parameters. Discontinuous icecap growth is noted for both a solar constant that is lower by a few percent and a change of orbital elements to favor cool Northern Hemisphere summers. This discontinuous sensitivity is discussed in the context of the Milankovitch theory of the <span class="hlt">ice</span> ages, and the associated branch structure is shown to be analogous to the 'small <span class="hlt">ice</span> cap' instability of simpler models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JSR...112....1W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JSR...112....1W"><span id="translatedtitle"><span class="hlt">Seasonally</span> chemical hydrology and ecological responses in frontal <span class="hlt">zone</span> of the central southern Yellow Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wei, Qin-Sheng; Li, Xian-Sen; Wang, Bao-Dong; Fu, Ming-Zhu; Ge, Ren-Feng; Yu, Zhi-Gang</p> <p>2016-06-01</p> <p>Based on annual-cycle survey data collected in 2006-2007 in the southern Yellow Sea (SYS) and analyses on the <span class="hlt">seasonally</span> chemical hydrologic characteristics of the boundary front of the Yellow Sea Cold Water Mass (YSCWM) and Yellow Sea Warm Current (YSWC), the <span class="hlt">seasonal</span> variations in upwelling along the frontal <span class="hlt">zone</span> were determined, and the ecological impacts of the front were investigated. During the generation and dissipation of the YSCWM, the implied upwelling along its western front exhibited <span class="hlt">seasonal</span> variation. The upwelling first shifted westward from the deep-water region to its westernmost point in summer then returned eastward. The intensity of the upwelling gradually increased from spring to summer and decreased in autumn. In spring, the existence of cold water west of the YSWC was not conducive to the reproduction of phytoplankton. Additionally, the front to the east of this cold water mass also made the western boundary of the phytoplankton bloom region in the central SYS more obvious, forming a prominent chlorophyll a (Chl-a) front. During the entire stratified <span class="hlt">season</span> (summer and autumn), the upwelling in the frontal <span class="hlt">zone</span> of the YSCWM played an essential role in maintaining the relatively high concentrations of Chl-a. In winter, the front that formed at the intersection of the YSWC and coastal cold water was also favorable for the formation of the high-Chl-a region. The distribution of anchovy biomass was closely related to the <span class="hlt">seasonal</span> variations in the position of the frontal <span class="hlt">zone</span>. In winter and spring, the tongue-shaped warm water and front associated with the intrusion of the YSWC into the SYS had a significant impact on anchovy. During the stratified <span class="hlt">season</span> in summer and autumn, the development of a front near the boundary of the YSCWM was an important physical driving mechanism for the dense distribution of anchovy. This work enhanced the study of the <span class="hlt">seasonal</span> relationships between the physical, chemical and biological processes in the frontal</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C11B0373O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C11B0373O"><span id="translatedtitle">Interannual and <span class="hlt">seasonal</span> variability in landfast sea <span class="hlt">ice</span> growth and properties at Barrow, Alaska: A comparison between observations and CICE model simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oggier, M.; Jin, M.; Eicken, H.</p> <p>2014-12-01</p> <p>Studies of long-term, regional variations of growth and properties of sea <span class="hlt">ice</span> are best served by a combination of field measurements and model simulations. We explore the utility of the Community <span class="hlt">Ice</span> Code (CICE) model, designed for fully coupled global climate models. CICE was run in standalone mode, with an integrated module that includes <span class="hlt">ice</span> salinity as a prognostic variable (Turner et al., doi:10.1002/jgrc.20171). We examine performance of the CICE salinity module by hindcasting interannual variability in the <span class="hlt">seasonal</span> cycle of first-year <span class="hlt">ice</span> salinity and temperature. Landfast <span class="hlt">ice</span>, monitored at Barrow, Alaska since 1999 (SIZONet.org), provides a suitable test case and reference. The model is forced with 6-hr weather data from the National Climate Data Center, except for precipitation and humidity provided by the NCEP reanalysis model. Simulations were run for the period 1948-2013, with a focus on 1999 to 2013 when observation data are available. Based on validation with measured <span class="hlt">ice</span> and snow thicknesses, a non-zero ocean-to-<span class="hlt">ice</span> heat flux has to be specified to reproduce the full <span class="hlt">seasonal</span> cycle. The model captures the broad <span class="hlt">seasonal</span> trends of key <span class="hlt">ice</span> properties and thickness, especially during the growth <span class="hlt">season</span>. During melt, significant deviations between observations and model output for <span class="hlt">ice</span> temperature and salinity are observed, in particular near the <span class="hlt">ice</span> surface where meltwater flushing is only partially captured by the CICE mushy-layer salinity module. With the exception of two years, the model captures interannual variability of <span class="hlt">ice</span> thickness and bulk <span class="hlt">ice</span> salinity well. Further work is required to improve the accuracy of the full <span class="hlt">seasonal</span> range of modeled salinity variations, especially during the melt <span class="hlt">season</span> when processes at the <span class="hlt">ice</span> interface are not well reproduced by the model. However, in conjunction with local validation data, CICE may serve as a tool to assess regional variations in key <span class="hlt">ice</span> properties on interannual to decadal time scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMGC31A1163Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMGC31A1163Z"><span id="translatedtitle">Changes in Arctic Sea <span class="hlt">Ice</span> Floe Size Distribution in the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> in a Thickness and Floe Size Distribution Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, J.; Stern, H. L., III; Hwang, P. B.; Schweiger, A. J. B.; Stark, M.; Steele, M.</p> <p>2015-12-01</p> <p>To better describe the state of sea <span class="hlt">ice</span> in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> (MIZ) with floes of varying thicknesses and sizes, both an <span class="hlt">ice</span> thickness distribution (ITD) and a floe size distribution (FSD) are needed. We have developed a FSD theory [Zhang et al., 2015] that is coupled to the ITD theory of Thorndike et al. [1975] in order to explicitly simulate the evolution of FSD and ITD jointly. The FSD theory includes a FSD function and a FSD conservation equation in parallel with the ITD equation. The FSD equation takes into account changes in FSD due to <span class="hlt">ice</span> advection, thermodynamic growth, and lateral melting. It also includes changes in FSD because of mechanical redistribution of floe size due to <span class="hlt">ice</span> opening, ridging and, particularly, <span class="hlt">ice</span> fragmentation induced by stochastic ocean surface waves. The floe size redistribution due to <span class="hlt">ice</span> fragmentation is based on the assumption that wave-induced breakup is a random process such that when an <span class="hlt">ice</span> floe is broken, floes of any smaller sizes have an equal opportunity to form, without being either favored or excluded. It is also based on the assumption that floes of larger sizes are easier to break because they are subject to larger flexure-induced stresses and strains than smaller floes that are easier to ride with waves with little bending; larger floes also have higher areal coverages and therefore higher probabilities to break. These assumptions with corresponding formulations ensure that the simulated FSD follows a power law as observed by satellites and airborne surveys. The FSD theory has been tested in the Pan-arctic <span class="hlt">Ice</span>/Ocean Modeling and Assimilation System (PIOMAS). The existing PIOMAS has 12 categories each for <span class="hlt">ice</span> thickness, <span class="hlt">ice</span> enthalpy, and snow depth. With the implementation of the FSD theory, PIOMAS is able to represent 12 categories of floe sizes ranging from 0.1 m to ~3000 m. It is found that the simulated 12-category FSD agrees reasonably well with FSD derived from SAR and MODIS images. In this study, we will</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A13B0308M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A13B0308M"><span id="translatedtitle">Satellite Remote Sensing of the Dependence of Homogeneous <span class="hlt">Ice</span> Nucleation on Latitude and <span class="hlt">Season</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mitchell, D. L.; Garnier, A.; Avery, M. A.; Erfani, E.</p> <p>2015-12-01</p> <p>Cirrus clouds can be thought of as belonging to one of two categories: those formed through (1) homo- and (2) heterogeneous <span class="hlt">ice</span> nucleation (henceforth hom and het) due to the very different microphysical and radiative properties associated with these two mechanisms. Hom cirrus will form only when atmospheric <span class="hlt">ice</span> nuclei (IN) are sufficiently low in concentration, and studies suggest that mineral dust may account for most IN globally. Hence the occurrence of hom and het cirrus is likely to depend on latitude and <span class="hlt">season</span> as mineral dust does, making satellite remote sensing the preferred method for characterizing this occurrence. A new understanding of thermal absorption in two split-window channels renders a reinterpretation of a standard CALIPSO satellite retrieval; the effective absorption optical depth ratio or βeff. Using earlier studies and aircraft measurements in cirrus clouds, βeff is found to be tightly related to the <span class="hlt">ice</span> particle number concentration/<span class="hlt">ice</span> water content ratio, or N/IWC, and thresholds for hom cirrus are estimated in terms of N/IWC and βeff. When applied to cold semi-transparent cirrus clouds, we find that (1) polar cirrus (T < -38 C) occur much more often during winter than summer and (2) hom cirrus prevail at high latitudes during winter, and during spring and fall over Antarctica. The figure shows estimates of the fraction of cirrus produced by hom (where βeff > 1.15) during January and August, where green is ~ 50% and red ~ 90-100%. These high N/IWC values associated with hom cirrus occur in regions where mineral dust concentrations are predicted to be minimal. This high N/IWC condition during winter is likely to have a strong greenhouse effect that may increase high latitude temperatures by 2-5°K relative to conditions where het cirrus dominates (Storelvmo et al. 2014, Philos. Trans. A, Royal Soc.). Thus, the lack of mineral dust in the high latitudes during winter may result in a strong warming influence over these regions. Moreover</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014TCD.....8.5763P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014TCD.....8.5763P"><span id="translatedtitle">Thin-<span class="hlt">ice</span> dynamics and <span class="hlt">ice</span> production in the Storfjorden polynya for winter-<span class="hlt">seasons</span> 2002/2003-2013/2014 using MODIS thermal infrared imagery</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Preußer, A.; Willmes, S.; Heinemann, G.; Paul, S.</p> <p>2014-11-01</p> <p>Spatial and temporal characteristics of the Storfjorden polynya, which forms regularly in the proximity of the islands Spitsbergen, Barentsøya and Edgeøya in the Svalbard archipelago under the influence of strong north-easterly winds, have been investigated for the period 2002/2003 to 2013/2014 using thermal infrared satellite imagery. Thin-<span class="hlt">ice</span> thicknesses were calculated from MODIS <span class="hlt">ice</span>-surface temperatures, combined with ECMWF ERA-Interim atmospheric reanalysis data in an energy-balance model. Based on calculated thin-<span class="hlt">ice</span> thicknesses, associated quantities like polynya area and total <span class="hlt">ice</span> production were derived and compared to previous remote sensing and modeling studies. A basic coverage-correction scheme was applied to account for cloud-gaps in the daily composites. The sea <span class="hlt">ice</span> in the Storfjorden area experiences a late fall freeze-up in several years over the 12 winter-period, with an increasing frequency of large polynya events until the end of December. During the regarded period, the mean polynya area is 4555.7 ± 1542.9 km2. The average <span class="hlt">ice</span> production in the fjord is estimated with 28.3 ± 8.5 km3 per winter and therefore lower than in previous studies. Despite this comparatively short record of 12 winter-<span class="hlt">seasons</span>, a significant positive trend of 20.2 km3 per decade could be detected, which contrasts earlier reports of a slightly negative trend in accumulated <span class="hlt">ice</span> production prior to 2002. Derived estimates underline the importance of this relatively small coastal polynya system considering its contribution to the cold halocline layer through salt release during <span class="hlt">ice</span> formation processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950029609&hterms=natural+pigments&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dnatural%2Bpigments','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950029609&hterms=natural+pigments&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dnatural%2Bpigments"><span id="translatedtitle"><span class="hlt">Seasonality</span> of coastal <span class="hlt">zone</span> scanner phytoplankton pigment in the offshore oceans</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Banse, K.; English, D. C.</p> <p>1994-01-01</p> <p>The NASA Global Ocean Data Set of plant pigment concentrations in the upper euphotic <span class="hlt">zone</span> is evaluated for diserning geographical and temporal patterns of <span class="hlt">seasonality</span> in the open sea. Monthly medians of pigment concentrations for all available years are generated for fields of approximately 77,000 sq km. For the climatological year, highest and lowest medians, month of occurence of the highest median, ratio of highest to lowest medians, and absolute range between the highest and lowest medians are mapped ocean-wide between 62.5 deg N and 62.5 deg S. <span class="hlt">Seasonal</span> cycles are depicted for 48 sites. In much of the offshore ocean, <span class="hlt">seasonality</span> of pigment is inferred to be driven almost equally by the interaction of the abiotic environment with phytoplankton physiology and the loss of cells from grazing. Special emphasis among natural domains or provinces is given to the Subantarctic water ring, with no <span class="hlt">seasonality</span> in its low chlorophyll concentrations in spite of strong environmental forcing, and the narrow Transition <span class="hlt">Zones</span>, a few degrees of latitude on the equatorial sides of the Subtropical Convergences of the southern hemisphere and their homologs in the northern hemisphere, which have late winter blooms caused by nutrient injection into the upper layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Icar..251..181C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Icar..251..181C"><span id="translatedtitle">Interannual and <span class="hlt">seasonal</span> changes in the north polar <span class="hlt">ice</span> deposits of Mars: Observations from MY 29-31 using MARCI</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Calvin, W. M.; James, P. B.; Cantor, B. A.; Dixon, E. M.</p> <p>2015-05-01</p> <p>The MARCI camera on the Mars Reconnaissance Orbiter provides daily synoptic coverage that allows monitoring of <span class="hlt">seasonal</span> cap retreat and interannual changes that occur between Mars year (MY) and over the northern summer. The northern <span class="hlt">seasonal</span> cap evolution was observed in MY 29, 30 and 31 (12/2007-04/2012). Observation over multiple Mars years allows us to compare changes between years as well as longer-term evolution of the high albedo deposits at the poles. Significant variability in the early <span class="hlt">season</span> is noted in all years and the retreating <span class="hlt">seasonal</span> cap edge is extremely dynamic. Detailed coverage of the entire <span class="hlt">seasonal</span> and residual <span class="hlt">ice</span> caps allows a broader view of variations in the high albedo coverage and identifies numerous regions where high albedo areas are changing with time. Large areas of disappearance and reappearance of high albedo features (Gemini Scopuli) are <span class="hlt">seasonally</span> cyclical, while smaller areas are variable on multi-year time scales (Abalso Mensae and Olympia Planitia). These <span class="hlt">seasonal</span> and interannual changes directly bear on the surface-atmosphere exchange of dust and volatiles and understanding the current net processes of deposition and erosion of the residual <span class="hlt">ice</span> deposits. Local and regional variation in high albedo areas reflects an interplay between frost deposition, evolution, and sublimation along with deposition and removal of dust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.U53C..02R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.U53C..02R"><span id="translatedtitle"><span class="hlt">Ice</span> Flow Dynamics and Outlet <span class="hlt">Zone</span> Morphology of Subglacial Lake Ellsworth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ross, N.; Smith, A.; Woodward, J.; Siegert, M. J.; Hindmarsh, R. C.; Corr, H.; King, E. C.; Vaughan, D.; Gillet-Chaulet, F.; Jay-Allemand, M.</p> <p>2009-12-01</p> <p>Subglacial Lake Ellsworth (SLE) is located beneath 2.95-3.28 km of <span class="hlt">ice</span> at the base of a deep subglacial trench ~30 km from the central <span class="hlt">ice</span> divide of the West Antarctic <span class="hlt">Ice</span> Sheet. Seismic reflection surveys indicate a maximum water column thickness of 155 m. Radio-echo sounding (RES) data have been used to map the lake, the morphology of the subglacial catchment and the structure and thickness of the overlying <span class="hlt">ice</span> sheet. Direct access, measurement and sampling of the lake waters and underlying sediments will be undertaken during the 2012-13 Antarctic field <span class="hlt">season</span> by the Lake Ellsworth Consortium. Internal <span class="hlt">ice</span> sheet layers throughout the SLE catchment have been picked and transformed into 3D surfaces as input for radar layer modelling. SLE is bounded on either side by steep, ~2 km high, mountainous subglacial topography. Over the lake, anomalies between modelled and observed internal layers are recognised near the steeper bedrock wall. We have sought to understand these in terms of perturbations to the velocity field from higher order mechanical effects as well as being caused by melt anomalies. A closely-spaced grid of RES lines (area coverage 7.5 x 7.5 km, line spacing ~500 m or less) has been used to map the outlet area of the lake in detail, with the aim of identifying possible drainage routes. The downstream margin of the lake is characterised by a pronounced topographic ridge, trending obliquely to <span class="hlt">ice</span> flow, which rises ~200 m above the elevation of the water surface. Beyond the ridge a 5 km by 0.75 km linear depression has been mapped. A narrow, low-lying breach in the ridge that connects to this depression may provide a subglacial hydrological outlet from SLE. Potential mechanisms for the formation of these features include: i) subaerial or subglacial processes pre-dating <span class="hlt">ice</span> sheet development; ii) water discharge from SLE. Such models are not necessarily mutually exclusive. The origins of the subglacial geomorphology and its possible influence on the routing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.H33C1628C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.H33C1628C&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Seasonal</span> variation of water quality in a lateral hyporheic <span class="hlt">zone</span> with response to dam operations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, X.; Chen, L.; Zhao, J.</p> <p>2015-12-01</p> <p>Aquatic environment of lateral hyporheic <span class="hlt">zone</span> in a regulated river were investigated <span class="hlt">seasonally</span> under fluctuated water levels induced by dam operations. Groundwater levels variations in preassembled wells and changes in electronic conductivity (EC), dissolved oxygen (DO) concentration, water temperature and pH in the hyporheic <span class="hlt">zone</span> were examined as environmental performance indicators for the water quality. Groundwater tables in wells were highly related to the river water levels that showed a hysteresis pattern, and the lag time is associated with the distances from wells to the river bank. The distribution of DO and EC were strongly related to the water temperature, indicating that the cold water released from up-reservoir could determine the biochemistry process in the hyporheic <span class="hlt">zone</span>. Results also showed that the hyporheic water was weakly alkaline in the study area but had a more or less uniform spatial distribution. Dam release-storage cycles were the dominant factor in changing lateral hyporheic flow and water quality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910031009&hterms=tie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dtie','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910031009&hterms=tie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dtie"><span id="translatedtitle">Sensitivity of passive microwave sea <span class="hlt">ice</span> concentration algorithms to the selection of locally and <span class="hlt">seasonally</span> adjusted tie points</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Steffen, Konrad; Schweiger, Axel</p> <p>1989-01-01</p> <p>The sensitivity of passive microwave sea-<span class="hlt">ice</span> concentration (SIC) algorithms to the selection of tie points was analyzed. SICs were derived with the NASA Team <span class="hlt">ice</span> algorithm for global tie points and for locally and <span class="hlt">seasonally</span> adjusted tie points. The SSM/I SIC was then compared to Landsat-MSS-derived SICs. Preliminary results show a mean difference of SSM/I- and Landsat-derived SICs for 50 x 50 km grid cells of 2.7 percent along the <span class="hlt">ice</span> edge of the Beaufort Sea during fall with local tie points. The accuracy decreased to 9.7 percent when global tie points were used. During freeze-up in the Beaufort Sea, with grey <span class="hlt">ice</span> and nilas as dominant <span class="hlt">ice</span> cover, the mean difference was 4.3 percent for local tie points and 13.9 percent for global tie points. For the spring <span class="hlt">ice</span> cover in the Bering Sea a mean difference of 4.4 percent for local tie points and 15.7 percent for global tie points was found. This large difference reveals some limitations of the NASA-Team algorithm under freeze-up and spring conditions (thin <span class="hlt">ice</span> areas).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A11Q..01S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A11Q..01S"><span id="translatedtitle"><span class="hlt">Seasonal</span> and spatial variability of heterogeneous <span class="hlt">ice</span> formation in stratiform clouds and its possible impact on precipitation formation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seifert, P.; Ansmann, A.; Baars, H.; Buehl, J.; Kanitz, T.; Bohlmann, S.; Engelmann, R.; Kunz, C.</p> <p>2015-12-01</p> <p>Lidar observations of stratiform mid-level clouds were used to investigate the efficiency of heterogeneous <span class="hlt">ice</span> nucleation as a function of cloud top temperature. The long-term lidar-based cloud datasets were collected in Germany (51°N,12°E), in southeastern China (22°N,112°E), Cape Verde (15°N,24°W), the Amazon Basin (1°N,60°W), South Africa (34°S,19°E), and southern Chile (53°S,71°W). They thus cover a variety of northern- and southern latitudinal belts from the midlatitudes to the tropics. Observations of the depolarization ratio were used to categorize the observed cloud layers into either <span class="hlt">ice</span>-free (no depolarized signals observed) or <span class="hlt">ice</span>-containing clouds (signals depolarized by scattering at <span class="hlt">ice</span> crystals). Strong hemispheric and regional differences were observed in the heterogeneous <span class="hlt">ice</span> formation efficiency at the different sites, especially in the high-temperature range between -20 and 0 °C. The fraction of <span class="hlt">ice</span> containing clouds in this temperature range is highest at the northern-latitudinal sites of Germany and southeastern China. Over Leipzig, 50% of all clouds contain <span class="hlt">ice</span> at -10 °C. In contrast, over southern Chile virtually no <span class="hlt">ice</span>-containing clouds were observed between -20 and 0 °C. <span class="hlt">Seasonal</span> differences in the <span class="hlt">ice</span>-cloud fraction were found over Germany and the Amazon Basin. The observed regional, hemispheric and <span class="hlt">seasonal</span> contrasts can be explained by differences in the aerosol concentration at cloud level above the different sites. Cloud vertical motion (observed with Doppler lidar), which also determine the microphysical cloud evolution, were found to be similar for all cloud layers. From combined observations of cloud radar and lidar at Leipzig it was in addition found that <span class="hlt">ice</span> water contents of below approx. 10-6kg/m³ cannot be detected with lidar. Clouds classified as pure liquid from the lidar-only observations thus could contain <span class="hlt">ice</span> water contents of below that threshold. Considering the hemispheric differences in heterogeneous</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMGC31C..07S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMGC31C..07S"><span id="translatedtitle"><span class="hlt">Seasonal</span> Changes in the Marine Production Cycles in Response to Changes in Arctic Sea <span class="hlt">Ice</span> and Upper Ocean Circulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Spitz, Y. H.; Ashjian, C. J.; Campbell, R. G.; Steele, M.; Zhang, J.</p> <p>2011-12-01</p> <p>Significant <span class="hlt">seasonal</span> changes in arctic sea <span class="hlt">ice</span> have been observed in recent years, characterized by unprecedented summer melt-back. As summer sea <span class="hlt">ice</span> extent shrinks to record low levels, the peripheral seas of the Arctic Ocean are exposed much earlier to atmospheric surface heat flux, resulting in longer and warmer summers with more oceanic heat absorption. The changing <span class="hlt">seasonality</span> in the arctic <span class="hlt">ice</span>/ocean system will alter the timing, magnitude, duration, and pattern of marine production cycles by disrupting key trophic linkages and feedbacks in planktonic food webs. We are using a coupled pan-arctic Biology/<span class="hlt">Ice</span>/Ocean Modeling and Assimilation System (BIOMAS) to investigate the changes in the patterns of <span class="hlt">seasonality</span> in the arctic physical and biological system. Focus on specific regions of the Arctic, such as the Chukchi Sea, the Beaufort Sea and the adjacent central Arctic, reveals that changes in the timing of the spring bloom, its duration and the response of the secondary producers vary regionally. The major changes are, however, characterized by an earlier phytoplankton bloom and a slight increase of the biomass. In addition, the largest response in the secondary producers is seen in the magnitude of the microzooplankton concentration as well as in the period (early summer to late fall) over which the microzooplankton is present.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DSRII.123...69J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DSRII.123...69J"><span id="translatedtitle">Pelagic ciliate communities within the Amundsen Sea polynya and adjacent sea <span class="hlt">ice</span> <span class="hlt">zone</span>, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiang, Yong; Liu, Qian; Yang, Eun Jin; Wang, Min; Kim, Tae Wan; Cho, Kyoung-Ho; Lee, SangHoon</p> <p>2016-01-01</p> <p>Polynyas, areas of open water surrounded by sea <span class="hlt">ice</span>, are sites of intense primary production and ecological hotspots in the Antarctic Ocean. This study determined the spatial variation in communities of pelagic ciliates in an Amundsen Sea polynya (ASP) and adjacent sea <span class="hlt">ice</span> <span class="hlt">zones</span> (SIZ) during austral summer from February to March 2012, and the results were compared with biotic and abiotic environmental factors. The species number, abundance and biomass were higher in the ASP than SIZ. Canonical analysis indicated that the communities in the ASP were distinct from those under the sea <span class="hlt">ice</span>. The pelagic ciliate community structure was closely correlated with environmental variability. Several primary environmental variables, both alone and in combination, were found to affect community spatial patterns. The ciliate biomasses in the ASP and SIZ areas were both significantly correlated with total and nano-Chl a. This analysis of the ciliated microzooplankton communities associated with high primary production provides new insights into the roles of ciliates in biogeochemical cycles in high-latitude polynyas. Additionally, our findings provide detailed data on the composition, distribution, and structure of polynya ciliate communities in the Amundsen Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012Geolg..18...65G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012Geolg..18...65G"><span id="translatedtitle">Sedimentary record of a Pleistocene <span class="hlt">ice</span>-sheet interlobate <span class="hlt">zone</span> (NE Poland)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gruszka, Beata; Morawski, Wojciech; Zieliński, Tomasz</p> <p>2012-08-01</p> <p>Well developed NE-SW trending corridors of outwash in NE Poland are associated with a series of lakes with a similar direction of elongation. The glaciofluvial corridor under study consists of parallel ridges with associated channels and kames. The deposits are flanked by till and hummocky terrain. The gravel ridges are composed of sand and gravel deposits that are cross-stratified, massive or graded, and that contain cut-and-fill structures and large intra-clasts of sand and gravel. Locally the deposits show normal faults. The succession of one of the ridges is interpreted to reflect the infilling of a braided channel in a crevasse. Sedimentation took place in some phases when the <span class="hlt">ice</span>-sheet regime changed from active to stagnant. Sandy-gravel ridges occur within this complex perpendicular to the Weichselian <span class="hlt">ice</span>-sheet margin. The corridor is interpreted as an interlobate area in the <span class="hlt">zone</span> between the Warmia and Mazury <span class="hlt">ice</span> lobes. The braided-channel deposits are not comparable to typical Polish sandurs. The lithofacies characteristics show higher energy conditions, and the channels are deeper than those typical of Pleistocene lowland sandurs. The sand and gravel ridges are interpreted as interlobate eskers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ClDy...37.2167U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ClDy...37.2167U"><span id="translatedtitle"><span class="hlt">Seasonally</span> asymmetric transition of the Asian monsoon in response to <span class="hlt">ice</span> age boundary conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ueda, Hiroaki; Kuroki, Harumitsu; Ohba, Masamichi; Kamae, Youichi</p> <p>2011-12-01</p> <p>Modulation of a monsoon under glacial forcing is examined using an atmosphere-ocean coupled general circulation model (AOGCM) following the specifications established by Paleoclimate Modelling Intercomparison Project phase 2 (PMIP2) to understand the air-sea-land interaction under different climate forcing. Several sensitivity experiments are performed in response to individual changes in the continental <span class="hlt">ice</span> sheet, orbital parameters, and sea surface temperature (SST) in the Last Glacial Maximum (LGM: 21 ka) to evaluate the driving mechanisms for the anomalous <span class="hlt">seasonal</span> evolution of the monsoon. Comparison of the model results in the LGM with the pre-industrial (PI) simulation shows that the Arabian Sea and Bay of Bengal are characterized by enhancement of pre-monsoon convection despite a drop in the SST encompassing the globe, while the rainfall is considerably suppressed in the subsequent monsoon period. In the LGM winter relative to the PI, anomalies in the meridional temperature gradient (MTG) between the Asian continents minus the tropical oceans become positive and are consistent with the intensified pre-monsoon circulation. The enhanced MTG anomalies can be explained by a decrease in the condensation heating relevant to the suppressed tropical convection as well as positive insolation anomalies in the higher latitude, showing an opposing view to a warmer future climate. It is also evident that a latitudinal gradient in the SST across the equator plays an important role in the enhancement of pre-monsoon rainfall. As for the summer, the sensitivity experiments imply that two <span class="hlt">ice</span> sheets over the northern hemisphere cools the air temperature over the Asian continent, which is consistent with the reduction of MTG involved in the attenuated monsoon. The surplus pre-monsoon convection causes a decrease in the SST through increased heat loss from the ocean surface; in other words, negative ocean feedback is also responsible for the subsequent weakening of summer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008DSRII..55..365W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008DSRII..55..365W"><span id="translatedtitle">Summertime mixed layer development in the marginal sea <span class="hlt">ice</span> <span class="hlt">zone</span> off the Mawson coast, East Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Williams, G. D.; Nicol, S.; Raymond, B.; Meiners, K.</p> <p>2008-02-01</p> <p>Two small-scale Antarctic marine ecosystem surveys were conducted offshore from the Mawson coast (61-66∘E), in the austral summers of January 2001 and 2003. Striking differences were observed in the state of the marine ecosystem between the surveys; in particular krill abundance and penguin breeding success were significantly lower in 2003. In this paper we examine the variability in the physical oceanography between the two surveys, and identify the development of the summer mixed layer (SML) as the key physical process influencing the differences in ecological conditions. The mixed layer in 2003 was warmer, fresher and reduced in both dissolved oxygen content and fluorescence relative to 2001. In 2001 the mean mixed-layer depth was 68.5±12.4m. In 2003, the mean mixed-layer depth was 33.8±11.2m, and increased through the remaining 14 days of the survey. The SML in 2003 was underdeveloped by over a month relative to the 2001 hydrography and we relate this to the <span class="hlt">seasonal</span> variability in the pattern and timing of sea-<span class="hlt">ice</span> melt. AVHRR satellite images show a region of fast <span class="hlt">ice</span> against the Mawson coast that had greater spatial and temporal extent in 2003. We conclude that delayed mixed layer development due to persistent sea <span class="hlt">ice</span> is likely to have a negative impact on the marine ecosystem of the Antarctic shelf. This may have important implications for predicting the impact of future variability in the sea-<span class="hlt">ice</span> growth/melt transition due to climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JGRC..107.3096B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JGRC..107.3096B"><span id="translatedtitle">Temporal and spatial variability of surface fluxes over the <span class="hlt">ice</span> edge <span class="hlt">zone</span> in the northern Baltic Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brümmer, B.; Schröder, D.; Launiainen, J.; Vihma, T.; Smedman, A.-S.; Magnusson, M.</p> <p>2002-08-01</p> <p>Three land-fast <span class="hlt">ice</span> stations (one of them was the Finnish research <span class="hlt">ice</span> breaker Aranda) and the German research aircraft Falcon were applied to measure the turbulent and radiation fluxes over the <span class="hlt">ice</span> edge <span class="hlt">zone</span> in the northern Baltic Sea during the Baltic Air-Sea-<span class="hlt">Ice</span> Study (BASIS) field experiment from 16 February to 6 March 1998. The temporal and spatial variability of the surface fluxes is discussed. Synoptic weather systems passed the experimental area in a rapid sequence and dominated the conditions (wind speed, air-surface temperature difference, cloud field) for the variability of the turbulent and radiation fluxes. At the <span class="hlt">ice</span> stations, the largest upward sensible heat fluxes of about 100 Wm-2 were measured during the passage of a cold front when the air cooled faster (-5 K per hour) than the surface. The largest downward flux of about -200 Wm-2 occurred during warm air advection when the air temperature reached +10°C but the surface temperature remained at 0°C. Spatial variability of fluxes was observed from the small scale (scale of <span class="hlt">ice</span> floes and open water spots) to the mesoscale (width of the <span class="hlt">ice</span> edge <span class="hlt">zone</span>). The degree of spatial variability depends on the synoptic situation: during melting conditions downward heat fluxes were the same over <span class="hlt">ice</span> and open water, whereas during strong cold-air advection upward heat fluxes differed by more than 100 Wm-2. A remarkable amount of grey <span class="hlt">ice</span> with intermediate surface temperature was observed. The <span class="hlt">ice</span> in the Baltic Sea cannot be described by one <span class="hlt">ice</span> type only.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.C24A..03K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.C24A..03K"><span id="translatedtitle"><span class="hlt">Seasonal</span> climate information preserved within West Antarctic <span class="hlt">ice</span> cores and its relation to large-scale atmospheric circulation and regional sea <span class="hlt">ice</span> variations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Küttel, M.; Steig, E. J.; Ding, Q.; Battisti, D. S.</p> <p>2010-12-01</p> <p>Recent evidence suggests that West Antarctica has been warming since at least the 1950s. With the instrumental record being limited to the mid-20th century, indirect information from stable isotopes (δ18O and δD, hereafter collectively δ) preserved within <span class="hlt">ice</span> cores have commonly been used to place this warming into a long term context. Here, using a large number of δ records obtained during the International Trans-Antarctic Scientific Expedition (ITASE), past variations in West Antarctic δ are not only investigated over time but also in space. This study therefore provides an important complement to longer records from single locations as e.g. the currently being processed West Antarctic <span class="hlt">ice</span> sheet (WAIS) Divide <span class="hlt">ice</span> core. Although snow accumulation rates at the ITASE sites in West Antarctica are variable, they are generally high enough to allow studies on sub-annual scale over the last 50-100 years. Here, we show that variations in δ in this region are strongly related to the state of the large-scale atmospheric circulation as well as sea <span class="hlt">ice</span> variations in the adjacent Southern Ocean, with important <span class="hlt">seasonal</span> changes. While a strong relationship to sea <span class="hlt">ice</span> changes in the Ross and Amundsen Sea as well as to the atmospheric circulation offshore is found during austral fall (MAM) and winter (JJA), only modest correlations are found during spring (SON) and summer (DJF). Interestingly, the correlations with the atmospheric circulation in the latter two <span class="hlt">seasons</span> have the strongest signal over the Antarctic continent, but not offshore - an important difference to MAM and JJA. These <span class="hlt">seasonal</span> changes are in good agreement with the <span class="hlt">seasonally</span> varying predominant circulation: meridional with more frequent storms in the Amundsen Sea during MAM and JJA and more zonal and stable during SON and DJF. The relationship to regional temperature is similarly <span class="hlt">seasonally</span> variable with highest correlations found during MAM and JJA. Notably, the circulation pattern found to be strongest</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7146760','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7146760"><span id="translatedtitle">Glacioclimatological study of Perennial <span class="hlt">Ice</span> in the Fuji <span class="hlt">Ice</span> Cave, Japan. Part I. <span class="hlt">Seasonal</span> variation and mechanism of maintenance</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ohata, Tetsuo; Furukawa, Teruo; Higuchi, Keiji )</p> <p>1994-08-01</p> <p>Perennial cave <span class="hlt">ice</span> in a cave located at Mt. Fuji in central Japan was studied to investigate the basic characteristics and the cause for existence of such <span class="hlt">ice</span> under warm ground-level climate considering the <span class="hlt">ice</span> cave as a thermal and hydrological system. Fuji <span class="hlt">Ice</span> Cave is a lava tube cave 150 m in length with a collapsed part at the entrance. Measurements from 1984 to 1986 showed that the surface-level change of floor <span class="hlt">ice</span> occurred due to freezing and melting at the surface and that melting at the bottom of the <span class="hlt">ice</span> was negligible. The annual amplitude of change in surface level was larger near the entrance. Meterological data showed that the cold air inflow to the cave was strong in winter, but in summer the cave was maintained near 0[degrees]C with only weak inflow of warm air. The predominant wind system was from the entrance to the interior in both winter and summer, but the spatial scale of the wind system was different. Heat budget consideration of the cave showed that the largest component was the strong inflow of subzero dry air mass in winter. Cooling in winter was compensated for by summer inflow of warm air, heat transport from the surrounding ground layer, and loss of sensible heat due to cooling of the cave for the observed year. Strong inflow of cold air and weak inflow of warm air, which is extremely low compared to the ground level air, seemed to be the most important condition. Thus the thermal condition of the cave is quasi-balanced at the presence condition below 0[degrees]C with <span class="hlt">ice</span>. It can be said that the interrelated result of the climatological and special structural conditions makes this cave very cold, and allows perennial <span class="hlt">ice</span> to exist in the cave. Other climatological factors such as precipitation seem to be minor factors. 17 refs., 3 figs., 3 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018510','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018510"><span id="translatedtitle">Effects of thermal vapor diffusion on <span class="hlt">seasonal</span> dynamics of water in the unsaturated <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Milly, P.C.D.</p> <p>1996-01-01</p> <p>The response of water in the unsaturated <span class="hlt">zone</span> to <span class="hlt">seasonal</span> changes of temperature (T) is determined analytically using the theory of nonisothermal water transport in porous media, and the solutions are tested against field observations of moisture potential and bomb fallout isotopic (36Cl and3H) concentrations. <span class="hlt">Seasonally</span> varying land surface temperatures and the resulting subsurface temperature gradients induce thermal vapor diffusion. The annual mean vertical temperature gradient is close to zero: however, the annual mean thermal vapor flux is downward, because the temperature-dependent vapor diffusion coefficient is larger, on average, during downward diffusion (occurring at high T) than during upward diffusion (low T). The annual mean thermal vapor flux is shown to decay exponentially with depth; the depth (about 1 m) at which it decays to ??-1 of its surface value is one half of the corresponding decay depth for the amplitude of <span class="hlt">seasonal</span> temperature changes. This depth-dependent annual mean flux is effectively a source of water, which must be balanced by a flux divergence associated with other transport processes. In a relatively humid environment the liquid fluxes greatly exceed the thermal vapor fluxes, so such a balance is readily achieved without measurable effect on the dynamics of water in the unsaturated <span class="hlt">zone</span>. However, if the mean vertical water flux through the unsaturated <span class="hlt">zone</span> is very small (<1 mm y-1), as it may be at many locations in a desert landscape, the thermal vapor flux must be balanced mostly by a matric-potential-induced upward flux of water. This return flux may include both vapor and liquid components. Below any near-surface <span class="hlt">zone</span> of weather- related fluctuations of matric potential, maintenance of this upward flux requires an increase with depth in the annual mean matric potential; this theoretical prediction is supported by long-term field measurements in the Chihuahuan Desert. The analysis also makes predictions, confirmed by the field</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.C53D0704N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.C53D0704N"><span id="translatedtitle">An <span class="hlt">ice</span> core record of net snow accumulation and <span class="hlt">seasonal</span> snow chemistry at Mt. Waddington, southwest British Columbia, Canada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neff, P. D.; Steig, E. J.; Clark, D. H.; McConnell, J. R.; Pettit, E. C.; Menounos, B.</p> <p>2011-12-01</p> <p>We recovered a 141 m <span class="hlt">ice</span> core from Combatant Col (51.39°N, 125.22°W, 3000 m asl) on the flank of Mt. Waddington, southern Coast Mountains, British Columbia, Canada. Aerosols and other impurities in the <span class="hlt">ice</span> show unambiguous <span class="hlt">seasonal</span> variations, allowing for annual dating of the core. Clustered melt layers, originating from summer surface heating, also aid in the dating of the core. <span class="hlt">Seasonality</span> in water stable isotopes is preserved throughout the record, showing little evidence of diffusion at depth, and serves as an independent verification of the timescale. The annual signal of deuterium excess is especially well preserved. The record of lead deposition in the core agrees with those of <span class="hlt">ice</span> cores from Mt. Logan and from Greenland, with a sharp drop-off in concentration in the 1970s and early 1980s, further validating the timescales. Despite significant summertime melt at this mid-latitude site, these data collectively reveal a continuous and annually resolved 36-year record of snow accumulation. We derived an accumulation time series from the Mt. Waddington <span class="hlt">ice</span> core, after correcting for <span class="hlt">ice</span> flow. Years of anomalously high or low snow accumulation in the core correspond with extremes in precipitation data and geopotential height anomalies from reanalysis data that make physical sense. Specifically, anomalously high accumulation years at Mt. Waddington correlate with years where "Pineapple Express" atmospheric river events bring large amounts of moisture from the tropical Pacific to western North America. The Mt. Waddington accumulation record thus reflects regional-scale climate. These results demonstrate the potential of <span class="hlt">ice</span> core records from temperate glaciers to provide meaningful paleoclimate information. A longer core to bedrock (250-300 m) at the Mt. Waddington site could yield <span class="hlt">ice</span> with an age of several hundred to 1000 years.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20100030621&hterms=Arctic+Sea&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DArctic%2BSea','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20100030621&hterms=Arctic+Sea&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DArctic%2BSea"><span id="translatedtitle">Recent Changes in Arctic Sea <span class="hlt">Ice</span> Melt Onset, Freeze-Up, and Melt <span class="hlt">Season</span> Length</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Markus, Thorsten; Stroeve, Julienne C.; Miller, Jeffrey</p> <p>2010-01-01</p> <p>In order to explore changes and trends in the timing of Arctic sea <span class="hlt">ice</span> melt onset and freeze-up and therefore melt <span class="hlt">season</span> length, we developed a method that obtains this information directly from satellite passive microwave data, creating a consistent data set from 1979 through present. We furthermore distinguish between early melt (the first day of the year when melt is detected) and the first day of continuous melt. A similar distinction is made for the freeze-up. Using this method we analyze trends in melt onset and freeze-up for 10 different Arctic regions. In all regions except for the Sea of Okhotsk, which shows a very slight and statistically insignificant positive trend (O.4 days/decade), trends in melt onset are negative, i.e. towards earlier melt. The trends range from -1.0day/decade for the Bering Sea to -7.3 days/decade for the East Greenland Sea. Except for the Sea of Okhotsk all areas also show a trend towards later autumn freeze onset. The Chukchi/Beaufort Seas and Laptev/East Siberian Seas observe the strongest trends with 7 days/decade. For the entire Arctic, the melt <span class="hlt">season</span> length has increased by about 20 days over the last 30 years. Largest trends of over 1O days/decade are seen for Hudson Bay, the East Greenland Sea the Laptev/East Siberian Seas, and the Chukchi/Beaufort Seas. Those trends are statistically significant a1 the 99% level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990JGR....9522229N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990JGR....9522229N"><span id="translatedtitle">Physical and biological oceanographic interaction in the spring bloom at the Bering Sea marginal <span class="hlt">ice</span> edge <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Niebauer, H. J.; Alexander, Vera; Henrichs, Susan</p> <p>1990-12-01</p> <p>At the edge of the melting sea <span class="hlt">ice</span> pack in the Bering Sea in spring, physical, biological, and chemical oceanographic processes combine to generate a short-lived, intense phytoplankton bloom that is associated with the retreating <span class="hlt">ice</span> edge. The bloom begins a week or so before the first of May triggered by insolation and by the low-salinity meltwater stratification in the presence of high nitrate concentrations (˜ > 25 μM). Meltwater (salinity) stratification delineates <span class="hlt">ice</span> edge blooms from open water blooms where temperature gradients generate the stratification. Five cross-<span class="hlt">ice</span> sections of temperature, salinity, σt, chlorophyll, and nitrate are presented as a time series from April 27 to May 5 illustrating the bloom. Evidence of two separate but concurrent blooms in the <span class="hlt">ice</span> edge <span class="hlt">zone</span> are presented. In addition, meteorological and oceanographic conditions were observed that should have been conducive to <span class="hlt">ice</span> edge up welling. While significant <span class="hlt">ice</span> and water movement occurred, upwelling was not observed. Finally, the Bering Sea <span class="hlt">ice</span> edge spring bloom is compared with other <span class="hlt">ice</span> edge systems in both hemispheres, showing that initial Bering Sea nitrate concentrations are among the highest observed but quickly become limiting owing to the rapid build up of phytoplankton populations. This primary production is not coupled to the pelagic Zooplankton because Zooplankton are largely absent on account of the cold temperatures. Observed maximum chlorophyll concentrations in the bloom are several times greater than those observed in other systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140010778','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140010778"><span id="translatedtitle">Changes in Arctic Melt <span class="hlt">Season</span> and Implications for Sea <span class="hlt">Ice</span> Loss</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stroeve, J. C.; Markus, T.; Boisvert, L.; Miller, J.; Barrett, A.</p> <p>2014-01-01</p> <p>The Arctic-wide melt <span class="hlt">season</span> has lengthened at a rate of 5 days dec-1 from 1979 to 2013, dominated by later autumn freeze-up within the Kara, Laptev, East Siberian, Chukchi and Beaufort seas between 6 and 11 days dec(exp -1). While melt onset trends are generally smaller, the timing of melt onset has a large influence on the total amount of solar energy absorbed during summer. The additional heat stored in the upper ocean of approximately 752MJ m(exp -2) during the last decade, increases sea surface temperatures by 0.5 to 1.5 C and largely explains the observed delays in autumn freeze-up within the Arctic Ocean's adjacent seas. Cumulative anomalies in total absorbed solar radiation from May through September for the most recent pentad locally exceed 300-400 MJ m(exp -2) in the Beaufort, Chukchi and East Siberian seas. This extra solar energy is equivalent to melting 0.97 to 1.3 m of <span class="hlt">ice</span> during the summer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol2/pdf/CFR-2012-title33-vol2-sec165-T08-0240.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol2/pdf/CFR-2012-title33-vol2-sec165-T08-0240.pdf"><span id="translatedtitle">33 CFR 165.T08-0240 - Safety <span class="hlt">Zone</span>; Kemah Boardwalk Summer <span class="hlt">Season</span> Fireworks, Galveston Bay, Kemah, TX.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... Summer <span class="hlt">Season</span> Fireworks, Galveston Bay, Kemah, TX. 165.T08-0240 Section 165.T08-0240 Navigation and... Areas Eighth Coast Guard District § 165.T08-0240 Safety <span class="hlt">Zone</span>; Kemah Boardwalk Summer <span class="hlt">Season</span> Fireworks...' radius around a fireworks barge located at approximate Latitude 29°32′57″ N, Longitude 095°00′31″ W....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006HyPr...20.1909H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006HyPr...20.1909H"><span id="translatedtitle">Pixel-scale evaluation of SSM/I sea-<span class="hlt">ice</span> algorithms in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> during early fall freeze-up</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hwang, Byong Jun; Barber, David G.</p> <p>2006-06-01</p> <p>Observed reduction in recent sea <span class="hlt">ice</span> areal extent and thickness has focused attention on the fact that the Arctic marine system appears to be responding to global-scale climate variability and change. Passive microwave remote-sensing data are the primary source underpinning these reports, yet problems remain in geophysical inversion of information on <span class="hlt">ice</span> type and concentration. Uncertainty in sea-<span class="hlt">ice</span> concentration (SIC) retrievals is highest in the summer and fall, when water occurs in liquid phase within the snow-sea-<span class="hlt">ice</span> system. Of particular scientific interest is the timing and rate of new <span class="hlt">ice</span> formation due to the control that this form of sea <span class="hlt">ice</span> has on mass, energy and gas fluxes across the ocean-sea-<span class="hlt">ice</span>-atmosphere interface. In this paper we examine the critical fall freeze-up period using in situ data from a ship-based and aerial survey programme known as the Canadian Arctic Shelf Exchange study combined with microwave and optical Earth observations data.Results show that: (1) the overall physical conditions observed from aerial survey photography were well matched with coincident moderate-resolution imaging spectroradiometer data and Radarsat ScanSAR imagery; (2) the shortwave albedo was linearly related to old <span class="hlt">ice</span> concentration derived from survey photography; (3) the three SSM/I SIC algorithms (NASA Team (NT), NASA Team 2 (NT2), and Bootstrap (BT)) showed considerable discrepancies in pixel-scale comparison with the Radarsat ScanSAR SICs well calibrated by the aerial survey data. The major causes of the discrepancies are attributed to (1) the inherent inability to detect the new thin <span class="hlt">ice</span> in the NT and BT algorithms, (2) mismatches of the thin-<span class="hlt">ice</span> tie point of the NT2 algorithm, and (3) sub-pixel ambiguity between the thin <span class="hlt">ice</span> and the mixture of open water and sea <span class="hlt">ice</span>. These results suggest the need for finer resolution of passive microwave sensors, such as AMSR-E, to improve the precision of the SSM/I SIC algorithms in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> during early</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.9852K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.9852K"><span id="translatedtitle">Time and space variability of freshwater content, heat content and <span class="hlt">seasonal</span> <span class="hlt">ice</span> melt in the Arctic Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Korhonen, Meri; Rudels, Bert; Zhou, Jinping</p> <p>2010-05-01</p> <p>The Arctic Ocean water column is strongly stratified in salinity due to large freshwater input from river runoff, net precipitation and the inflow of low salinity Pacific water through Bering Strait: The strong stability allows sea <span class="hlt">ice</span> to form in winter and to be exported. In summer <span class="hlt">seasonal</span> <span class="hlt">ice</span> melt adds freshwater to the stability in the upper part of the water column. The distribution of heat, relative to -1.9C, and freshwater, relative to 34.9, in the upper 1000m of the water column and in different areas of the Arctic Ocean, as well as the amount and distribution of <span class="hlt">seasonal</span> <span class="hlt">ice</span> melt have been determined from hydrographic data obtained from <span class="hlt">ice</span> breaker cruises conducted in the Arctic Ocean during the last 15 years. The water column is subdivided into six layers: the Polar Mixed Layer, the upper halocline (S<34), the lower halocline (S>34, T<0C), two Atlantic layers (T>0C) separated at the temperature maximum, and the intermediate layer (T<0C) down to 1000m. The time variability of thickness, freshwater content and heat content in these layers is then determined for the Nansen Basin, the Gakkel Ridge, the Amundsen Basin, the Lomonosov Ridge, the Makarov Basin, the northern Canada Basin and the southern Canada Basin. The temporal variations in freshwater content are largest in the uppermost layers, the Polar Mixed Layer and the upper halocline and magnify towards Bering Strait. The <span class="hlt">seasonal</span> <span class="hlt">ice</span> melt is estimated from the freshwater stored in the Polar Surface Layer above the temperature minimum indicating the depth of the local winter convection and homogenisation. The melt water content is computed relative to the salinity at the temperature minimum. The required latent heat of melting and the sensible heat stored above the temperature minimum are compared with the NCEP/NCAR reanalysis heat input data. The estimated freshwater input is 1-2m, in Nansen Basin usually below 1m and over the Lomonosov Ridge and in the Makarov Basin sometimes above 2m. This is close</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17330457','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17330457"><span id="translatedtitle">[Variability of vegetation growth <span class="hlt">season</span> in different latitudinal <span class="hlt">zones</span> of North China: a monitoring by NOAA NDVI and MSAVI].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Hong; Li, Xiaobing; Han, Ruibo; Ge, Yongqin</p> <p>2006-12-01</p> <p>In this study, North China was latitudinally divided into five <span class="hlt">zones</span>, i.e., 32 degrees - 36 degrees N (<span class="hlt">Zone</span> I), 36 degrees - 40 degrees N (<span class="hlt">Zone</span> II), 40 degrees - 44 degrees N (<span class="hlt">Zone</span> III), 44 degrees - 48 degrees N (<span class="hlt">Zone</span> IV) and 48 degrees - 52 degrees N (<span class="hlt">Zone</span> V), and the NOAA/ AVHRR NDVI and MSAVI time-series images from 1982 to 1999 were smoothed with Savitzky-Golay filter algorithm. Based on the EOF analysis, the principal components of NDVI and MSAVI for the vegetations in different latitudinal <span class="hlt">zones</span> of North China were extracted, the annual beginning and ending dates and the length of growth <span class="hlt">season</span> in 1982 - 1999 were estimated, and the related parameters were linearly fitted, aimed to analyze the variability of vegetation growth <span class="hlt">season</span>. The results showed that the beginning date of the growth <span class="hlt">season</span> in different <span class="hlt">zones</span> tended to be advanced, while the ending date tended to be postponed with increasing latitude. The length of the growth <span class="hlt">season</span> was also prolonged, with the prolonging time exceeded 10 days.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016TCry...10.2069W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016TCry...10.2069W"><span id="translatedtitle">Brief communication: Improved measurement of <span class="hlt">ice</span> layer density in <span class="hlt">seasonal</span> snowpacks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Watts, Tom; Rutter, Nick; Toose, Peter; Derksen, Chris; Sandells, Melody; Woodward, John</p> <p>2016-09-01</p> <p>The microstructure and density of <span class="hlt">ice</span> layers in snowpacks is poorly quantified. Here we present a new field method for measuring the density of <span class="hlt">ice</span> layers caused by melt or rain-on-snow events. The method was used on 87 <span class="hlt">ice</span> layer samples taken from natural and artificial <span class="hlt">ice</span> layers in the Canadian Arctic and mid-latitudes. Mean measured <span class="hlt">ice</span> layer density was 909 ± 28 kg m-3 with a standard deviation of 23 kg m-3, significantly higher than values typically used in the literature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C11A0335P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C11A0335P"><span id="translatedtitle">Distribution of Phytoplankton and Particulate Organic Carbon in the Beaufort Sea during the 2014 Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> Experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perry, M. J.; Lee, C.; Yang, E. J.; Cetinic, I.; Kang, S. H.</p> <p>2014-12-01</p> <p>Spatial and temporal distributions of phytoplankton and particulate organic carbon in the newly emerging marginal <span class="hlt">ice</span> <span class="hlt">zone</span> in the Beaufort Sea are assessed from autonomous Seaglider surveys in summer 2014 as part of the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> (MIZ) Experiment, an international project sponsored by ONR. In late July 2014 four Seagliders were deployed in the Beaufort Sea to follow the retreat of the MIZ. Sampling in open water, through the MIZ and under the <span class="hlt">ice</span> is expected through mid-September, with gliders navigating under <span class="hlt">ice</span> from moored acoustic sound sources embedded in the MIZ autonomous observing array. The sensor suite carried by Seagliders include temperature, temperature microstructure, salinity, oxygen, chlorophyll fluorescence, optical backscatter, and multi-spectral downwelling irradiance. A rigorous sensor inter-calibration program with simultaneous ship CTD and glider profiles is an essential component of glider deployment and recovery protocol, as well as during opportunistic glider encounters with the IBRV Araon during August. Ship-based water sampling will allow construction of regional libraries of optical proxies for chlorophyll, pigment spectral absorption coefficient, and particulate organic carbon. Since irradiance under the <span class="hlt">ice</span> is dependent on <span class="hlt">ice</span> thickness and presence of melt ponds and leads, phytoplankton distribution is expected to vary spatially. Both the vertical and horizontal distributions of pigment spectral absorption coefficients are expected to play a role in the feedback between phytoplankton and <span class="hlt">ice</span> melt. Glider data will allow us to apply a light and chlorophyll primary productivity model to estimate and compare phytoplankton productivity under various <span class="hlt">ice</span>-cover and <span class="hlt">ice</span>-free conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DPS....4830209L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DPS....4830209L"><span id="translatedtitle">The Effect of Carbon Dioxide (CO 2) <span class="hlt">Ice</span> Cloud Condensation on the Habitable <span class="hlt">Zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lincowski, Andrew; Meadows, Victoria; Robinson, Tyler D.; Crisp, David</p> <p>2016-10-01</p> <p>The currently accepted outer limit of the habitable <span class="hlt">zone</span> (OHZ) is defined by the "maximum greenhouse" limit, where Rayleigh scattering from additional CO2 gas overwhelms greenhouse warming. However, this long-standing definition neglects the radiative effects of CO2 clouds (Kopparapu, 2013); this omission was justified based on studies using the two-stream approximation, which found CO2 clouds to be highly likely to produce a net warming. However, recent comparisons of the radiative effect of CO2 clouds using both a two-stream and multi-stream radiative transfer model (Kitzmann et al, 2013; Kitzmann, 2016) found that the warming effect was reduced when the more sophisticated multi-stream models were used. In many cases CO2 clouds caused a cooling effect, meaning that their impact on climate could not be neglected when calculating the outer edge of the habitable <span class="hlt">zone</span>. To better understand the impact of CO2 <span class="hlt">ice</span> clouds on the OHZ, we have integrated CO2 cloud condensation into a versatile 1-D climate model for terrestrial planets (Robinson et al, 2012) that uses the validated multi-stream SMART radiative transfer code (Meadows & Crisp, 1996; Crisp, 1997) with a simple microphysical model. We present preliminary results on the habitable <span class="hlt">zone</span> with self-consistent CO2 clouds for a range of atmospheric masses, compositions and host star spectra, and the subsequent effect on surface temperature. In particular, we evaluate the habitable <span class="hlt">zone</span> for TRAPPIST-1d (Gillon et al, 2016) with a variety of atmospheric compositions and masses. We present reflectance and transit spectra of these cold terrestrial planets. We identify any consequences for the OHZ in general and TRAPPIST-1d in particular. This more comprehensive treatment of the OHZ could impact our understanding of the distribution of habitable planets in the universe, and provide better constraints for statistical target selection techniques, such as the habitability index (Barnes et al, 2015), for missions like JWST</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A11K0195B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A11K0195B"><span id="translatedtitle">Aircraft observations of the evolution of <span class="hlt">ice</span> surface conditions at the onset of the melt <span class="hlt">season</span> in the Beaufort Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Birnbaum, G.; Ehrlich, A.; Schwarz, P.; Lüpkes, C.; Dierking, W.; Hartmann, J.</p> <p>2012-12-01</p> <p>At the onset of the melt <span class="hlt">season</span> in the Arctic, the energy exchange between atmosphere, sea <span class="hlt">ice</span>, and ocean undergoes strong changes. Caused by melting of snow and formation of melt ponds and open leads the areally averaged albedo decreases dramatically and absorption of solar radiation is enhanced. To investigate these changes, the aircraft campaign MELTEX was performed from 11 May to 7 June, 2008 over the Beaufort Sea (region 69°N-74°N, 133°W-144°W). During the campaign, the sea <span class="hlt">ice</span> cover experienced several episodes with strong on-<span class="hlt">ice</span> warm-air advection from the Canadian Coast. Between these warm episodes, northerly flow with cold-air advection from the inner Arctic caused an interruption of melting and melt pond evolution and even a temporary refreezing. To quantify the evolution of <span class="hlt">ice</span> surface conditions, the aircraft POLAR 5 was equipped with a digital reflex camera, broadband radiation sensors, a spectral albedometer with active horizontal stabilization, and further meteorological instruments. Images of seven flights were analyzed by means of a supervised classification employing the maximum likelihood method to derive the areal fraction of different surface classes. Areally averaged broadband and spectral albedo was derived for clear-sky conditions only to allow for a better comparison of values. On 11 May, the <span class="hlt">ice</span> conditions were still characteristic for late winter. The maximum broadband albedo for snow covered <span class="hlt">ice</span> was 0.82. On 26 May, already 21,6% of the sea <span class="hlt">ice</span> surface right north of a coastal polynya consisted of wet <span class="hlt">ice</span> (19,4%) and shallow melt ponds (2,2%). Broadband albedo measurements indicated an average value of 0.57 for melting snow and bare <span class="hlt">ice</span>. The most enhanced stage of melting was encountered on 6 June for fast <span class="hlt">ice</span> in Franklin and Darnley Bay, south of the Amundsen Gulf. The total fraction of melt ponds and particle-laden sea <span class="hlt">ice</span> amounted to 45,0±16,7% with an average broadband albedo of 0.16. The average albedo of the remaining clean</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920073994&hterms=parkinson&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dparkinson','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920073994&hterms=parkinson&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dparkinson"><span id="translatedtitle">Spatial patterns of increases and decreases in the length of the sea <span class="hlt">ice</span> <span class="hlt">season</span> in the north polar region, 1979-1986</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parkinson, Claire L.</p> <p>1992-01-01</p> <p>Recently it was reported that sea <span class="hlt">ice</span> extents in the Northern Hemisphere showed a very slight but statistically significant decrease over the 8.8-year period of the Nimbus 7 scanning multichannel microwave radiometer (SMMR) data set. In this paper the same SMMR data are used to reveal spatial patterns in increasing and decreasing sea <span class="hlt">ice</span> coverage. Specifically, the length of the <span class="hlt">ice</span> <span class="hlt">season</span> is mapped for each full year of the SMMR data set (1979-1986), and the trends over the 8 years in these <span class="hlt">ice</span> <span class="hlt">season</span> lengths are also mapped. These trends show considerable spatial coherence, with a shortening in the sea <span class="hlt">ice</span> <span class="hlt">season</span> apparent in much of the eastern hemisphere of the north polar <span class="hlt">ice</span> cover, particularly in the Sea of Okhotsk, the Barents Sea, and the Kara Sea, and a lengthening of the sea <span class="hlt">ice</span> <span class="hlt">season</span> apparent in much of the western hemisphere of the north polar <span class="hlt">ice</span> cover, particularly in Davis Strait, the Labrador Sea, and the Beaufort Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C51A0684A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C51A0684A"><span id="translatedtitle">Using Seismic Noise Generated by Ocean Waves to Monitor <span class="hlt">Seasonal</span> and Secular Changes in Antarctic Sea <span class="hlt">Ice</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anthony, R. E.; Aster, R. C.; Thompson, D. W. J.; Reusch, D. B.</p> <p>2015-12-01</p> <p>The Earth's background seismic noise between ~1-30 seconds period is commonly dominated by microseisms that arise when oceanic wave energy and swell are converted to ground displacement as the waves crash and interact with the continental shelf. Peak power in the microseism bands at high-latitude stations typically coincides with large-scale extratropical cyclonic winter storm activity. However, due to the <span class="hlt">seasonal</span> formation of sea <span class="hlt">ice</span> around the continental shelves of polar regions, oceanic waves are impeded from efficiently exciting seismic energy, and annual peak microseism power thus occurs prior to the midwinter storm peak. We utilize recently collected seismic data from across the continent to show that power in three distinct microseism bands is found to be strongly anti-correlated with sea <span class="hlt">ice</span> extent, with the shorter period signals being exceptionally sensitive to local conditions. Particular focus is given to the Antarctic Peninsula, the strongest source of microseism energy on the continent, where we note a significant increase in primary microseism power attributable to near coastal sources from 1993-2012. This increase correlates with regional sea <span class="hlt">ice</span> loss driven by large-scale wind changes associated with strengthening of the Southern Annular Mode. Additionally, we use microseism analysis to explore changes in sea <span class="hlt">ice</span> strength and extent relative to wave state and storminess in the Southern Oceans. Investigation of microseism <span class="hlt">seasonality</span>, power, and decadal-scale trends in the Antarctic shows promise as a spatially integrated tool for monitoring and interpreting such sea <span class="hlt">ice</span> strength and extent metrics through time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP53B2341B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP53B2341B"><span id="translatedtitle">Sclerochronological analysis of Saxidomus gigantea: Implications for reconstructing past <span class="hlt">seasonality</span> and sea <span class="hlt">ice</span> extent in the Northern Pacific Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bassett, C.; Andrus, C. F. T.</p> <p>2015-12-01</p> <p>Sclerochronological analysis of biogenic carbonates provides valuable paleoenvironmental information. Oxygen isotope analysis of bivalve shell yields information on the temperature of the water in which the organism grew. However, in coastal environments, variations in δ18Owater may complicate the interpretation of shell isotope profiles. Measuring and comparing the length of <span class="hlt">seasonal</span> shell growth in select species of bivalves may complement isotopic analysis, together providing a more precise paleoclimate reconstruction. This project aims to determine the reliability of sclerochronological analysis of bivalves in reconstructing <span class="hlt">seasonality</span> along the Northwest Coast of North America. To compare bivalves growing at different <span class="hlt">seasonal</span> temperature conditions, samples of Saxidomus gigantea were collected from southern Alaska and northern British Columbia. Winter cessation lines were identified using oxygen isotope (δ18O) peaks from a profile of variation over the life of the clam, which was sampled sequentially from a section of its shell. Shell growth stops below ~4-5°C and so each winter cessation indicates temperatures lower than this threshold. Lunar-daily growth lines were counted between these winter growth cessation breaks, which quantitatively measure the length of the growing <span class="hlt">season</span>. The resulting data were compared between habitats to assess if this is a useful method of determining the length of the growing <span class="hlt">season</span>. If this method of assessing <span class="hlt">seasonality</span> appears valid, it can be applied to ancient shells abundant in archaeological shell middens to make inferences about past seawater conditions and potentially indicate the presence or absence of the conditions necessary for sea <span class="hlt">ice</span> accumulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C51A0672H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C51A0672H"><span id="translatedtitle">The Role of Clouds in Linking the Summer AO and Arctic Dipole to Summer Arctic Sea <span class="hlt">Ice</span> Extent Variability on <span class="hlt">Seasonal</span> and Interannual Timescales</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hegyi, B. M.; Deng, Y.; Taylor, P. C.</p> <p>2015-12-01</p> <p>The current skill of <span class="hlt">seasonal</span> and long-term sea <span class="hlt">ice</span> predictions from coupled general circulation models (GCMs) are limited due to insufficient initial conditions, insufficient model physics, and the influence of chaotic atmospheric variability. Since atmospheric variability is a limiting factor in sea <span class="hlt">ice</span> extent prediction, an improvement in the understanding of the relationship between atmospheric variability and sea <span class="hlt">ice</span> will help improve <span class="hlt">seasonal</span> and long-term sea <span class="hlt">ice</span> forecasting. As a first step to better understand this relationship, we investigate the link between atmospheric variability and sea <span class="hlt">ice</span> during the summer melt <span class="hlt">season</span> on <span class="hlt">seasonal</span> and interannual timescales, facilitated by a connecting (or bridging) physical mechanism. We characterize the summer atmospheric variability by both atmospheric eddy activity and by the two dominant modes of summer Arctic atmospheric variability, the Arctic Oscillation (AO) and the Arctic Dipole (AD). We hypothesize that anomalies in cloud fraction and the cloud liquid/<span class="hlt">ice</span> water content driven by atmospheric eddies and the AO/AD are an important bridging physical mechanism. Cloud fraction and cloud liquid/<span class="hlt">ice</span> water content anomalies change the downwelling radiation at the sea <span class="hlt">ice</span> surface, and thus affect the surface energy budget and sea <span class="hlt">ice</span> melt. Associated large-scale cloud property anomalies and surface cloud radiative effects are identified using a CloudSAT-CALIPSO-CERES-MODIS fusion cloud data set. Atmospheric eddies are defined in MERRA reanalysis data, and are classified by frequency into high-, low-, and <span class="hlt">seasonal</span>-scale eddies. Preliminary results suggest that in individual years, high-frequency atmospheric eddies help initiate sea <span class="hlt">ice</span> melt through associated total downwelling radiation anomalies. These downwelling radiation anomalies are associated with anomalously low and high cloud fraction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004DSRII..51.2327S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004DSRII..51.2327S"><span id="translatedtitle"><span class="hlt">Seasonality</span> of blue and fin whale calls and the influence of sea <span class="hlt">ice</span> in the Western Antarctic Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Širović, Ana; Hildebrand, John A.; Wiggins, Sean M.; McDonald, Mark A.; Moore, Sue E.; Thiele, Deborah</p> <p>2004-08-01</p> <p>The calling <span class="hlt">seasonality</span> of blue ( Balaenoptera musculus) and fin ( B. physalus) whales was assessed using acoustic data recorded on seven autonomous acoustic recording packages (ARPs) deployed from March 2001 to February 2003 in the Western Antarctic Peninsula. Automatic detection and acoustic power analysis methods were used for determining presence and absence of whale calls. Blue whale calls were detected year round, on average 177 days per year, with peak calling in March and April, and a secondary peak in October and November. Lowest calling rates occurred between June and September, and in December. Fin whale calling rates were <span class="hlt">seasonal</span> with calls detected between February and June (on average 51 days/year), and peak calling in May. Sea <span class="hlt">ice</span> formed a month later and retreated a month earlier in 2001 than in 2002 over all recording sites. During the entire deployment period, detected calls of both species of whales showed negative correlation with sea <span class="hlt">ice</span> concentrations at all sites, suggesting an absence of blue and fin whales in areas covered with sea <span class="hlt">ice</span>. A conservative density estimate of calling whales from the acoustic data yields 0.43 calling blue whales per 1000 n mi 2 and 1.30 calling fin whales per 1000 n mi 2, which is about one-third higher than the density of blue whales and approximately equal to the density of fin whales estimated from the visual surveys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4019199','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4019199"><span id="translatedtitle">Diurnal and <span class="hlt">Seasonal</span> Fluctuations in Rectal Temperature, Respiration and Heart Rate of Pack Donkeys in a Tropical Savannah <span class="hlt">Zone</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>AYO, Joseph O.; DZENDA, Tavershima; OLAIFA, Folashade; AKE, Stephen A.; SANI, Ismaila</p> <p>2014-01-01</p> <p>ABSTRACT The study was designed to determine diurnal and <span class="hlt">seasonal</span> changes in basic physiologic responses of donkeys adapted to the tropical Savannah. The rectal temperature (RT), respiratory rate (RR) and heart rate (HR) of six male Nubian pack donkeys, and the dry-bulb temperature (DBT), relative humidity and heat index of the experimental site were concurrently recorded hourly, from 06:00 h to 18:00 h (GMT +1), for three days, spread 1 week apart, during the cold-dry (harmattan), hot-dry and humid (rainy) <span class="hlt">seasons</span>, in an open grazing field. Values of the physiologic parameters recorded during the morning (06:00 h–11:00 h) were lower (P<0.001) than those obtained in the afternoon (12:00 h–15:00 h) and evening (16:00 h–18:00 h) hours in all <span class="hlt">seasons</span>, but the robustness of the diurnal rhythm differed (P<0.05) between <span class="hlt">seasons</span>. Many diurnal hourly DBT mean values recorded during the harmattan and hot-dry <span class="hlt">seasons</span> fell outside the established thermoneutral <span class="hlt">zone</span> for tropically-adapted donkeys, while those obtained during the rainy <span class="hlt">season</span> were within the <span class="hlt">zone</span>, indicating that the dry <span class="hlt">seasons</span> were more thermally stressful to the donkeys than the humid <span class="hlt">season</span>. Overall mean RT dropped (P<0.05) during the harmattan <span class="hlt">season</span>. The RR rose, while HR dropped (P<0.001) during the hot-dry <span class="hlt">season</span>. In conclusion, daytime and <span class="hlt">season</span> had profound influence on RT, RR and HR of the donkeys, therefore, diurnal and <span class="hlt">seasonal</span> variations should be taken into account during clinical evaluation before reaching conclusion on health status and fitness for work in donkeys. PMID:24834007</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.C11A0079H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.C11A0079H"><span id="translatedtitle">Field Measurement of Past and Present Meltwater Infiltration in the Percolation <span class="hlt">Zone</span> of the Greenland <span class="hlt">Ice</span> Sheet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harper, J. T.; Humphrey, N. F.; Pfeffer, W. T.; Brown, J. M.; Schuler, D. R.; Sturgis, D.</p> <p>2007-12-01</p> <p>We present results from a field campaign focused on meltwater infiltration and horizontal water transport processes in the percolation <span class="hlt">zone</span> of the Greenland <span class="hlt">Ice</span> Sheet. Field data were collected during a period of heavy melt in June/July 2007 along a ~50 km transect (from ~2000 m to ~1600 m elevation) of the EGIG line of west Greenland. Snow and firn stratigraphies of the upper 10 m were documented with snowpit measurements, core analysis of 21 firn cores drilled to 10+ m, and with over 60 km of constant offset radar profiles collected at a variety of frequencies. We also acquired 15 constant midpoint profiles to characterize depth-density relationships in the upper 80 meters of the firn column. Dye tracing experiments were used to identify meltwater migration pathways and to quantify the relative rates of horizontal and vertical water movement. Five thermister strings with 33 channels and a 30 min time base were installed for long term monitoring of the thermal signature of meltwater migration and <span class="hlt">ice</span> layer formation in the upper 10 m of firn. Two meteorological stations were installed to provide information on surface boundary conditions. Our work shows massive <span class="hlt">ice</span> layers (up to 0.4 m thick) form at depth under conditions of heavy surface melt. The <span class="hlt">ice</span> layers, however, lack spatial coherence over meter length scales and therefore allow vertical meltwater infiltration. Hence, we found no evidence of significant horizontal water transport along internal <span class="hlt">ice</span> layers within this elevation band of the GIS percolation <span class="hlt">zone</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GeoRL..42.1863C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GeoRL..42.1863C&link_type=ABSTRACT"><span id="translatedtitle">In situ measurements of an energetic wave event in the Arctic marginal <span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Collins, Clarence O.; Rogers, W. Erick; Marchenko, Aleksey; Babanin, Alexander V.</p> <p>2015-03-01</p> <p>R/V Lance serendipitously encountered an energetic wave event around 77°N, 26°E on 2 May 2010. Onboard GPS records, interpreted as the surface wave signal, show the largest waves recorded in the Arctic region with <span class="hlt">ice</span> cover. Comparing the measurements with a spectral wave model indicated three phases of interaction: (1) wave blocking by <span class="hlt">ice</span>, (2) strong attenuation of wave energy and fracturing of <span class="hlt">ice</span> by wave forcing, and (3) uninhibited propagation of the peak waves and an extension of allowed waves to higher frequencies (above the peak). Wave properties during fracturing of <span class="hlt">ice</span> cover indicated increased groupiness. Wave-<span class="hlt">ice</span> interaction presented binary behavior: there was zero transmission in unbroken <span class="hlt">ice</span> and total transmission in fractured <span class="hlt">ice</span>. The fractured <span class="hlt">ice</span> front traveled at some fraction of the wave group speed. Findings do not motivate new dissipation schemes for wave models, though they do indicate the need for two-way, wave-<span class="hlt">ice</span> coupling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26803740','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26803740"><span id="translatedtitle">Flow regulation manipulates contemporary <span class="hlt">seasonal</span> sedimentary dynamics in the reservoir fluctuation <span class="hlt">zone</span> of the Three Gorges Reservoir, China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tang, Qiang; Bao, Yuhai; He, Xiubin; Fu, Bojie; Collins, Adrian L; Zhang, Xinbao</p> <p>2016-04-01</p> <p>Since the launch of the Three Gorges Dam on the Yangtze River, a distinctive reservoir fluctuation <span class="hlt">zone</span> has been created and significantly modified by regular dam operations. Sediment redistribution within this artificial landscape differs substantially from that in natural fluvial riparian <span class="hlt">zones</span>, due to a specific hydrological regime comprising steps of water impoundment with increasing magnitudes and <span class="hlt">seasonal</span> water level fluctuation holding a range of sediment fluxes. This study reinterpreted post-dam sedimentary dynamics in the reservoir fluctuation <span class="hlt">zone</span> by stratigraphy determination of a 345-cm long sediment core, and related it to impact of the hydrological regime. <span class="hlt">Seasonality</span> in absolute grain-size composition of suspended sediment was applied as a methodological basis for stratigraphic differentiation. Sedimentary laminations with relatively higher proportions of sandy fractions were ascribed to sedimentation during the dry <span class="hlt">season</span> when proximal subsurface bank erosion dominates source contributions, while stratigraphy with a lower proportion of sandy fractions is possibly contributed by sedimentation during the wet <span class="hlt">season</span> when distal upstream surface erosion prevails. Chronology determination revealed non-linear and high annual sedimentation rates ranging from 21.7 to 152.1cm/yr. Although channel geomorphology may primarily determine the spatial extent of sedimentation, <span class="hlt">seasonal</span> sedimentary dynamics was predominantly governed by the frequency, magnitude, and duration of flooding. Summer inundation by natural floods with enhanced sediment loads produced from upstream basins induced higher sedimentation rates than water impoundment during the dry <span class="hlt">season</span> when distal sediment supply was limited. We thus conclude that flow regulation manipulates contemporary <span class="hlt">seasonal</span> sedimentary dynamics in the reservoir fluctuation <span class="hlt">zone</span>, though little impact on total sediment retention rate was detected. Ongoing reductions in flow and sediment supply under human disturbance may</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26803740','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26803740"><span id="translatedtitle">Flow regulation manipulates contemporary <span class="hlt">seasonal</span> sedimentary dynamics in the reservoir fluctuation <span class="hlt">zone</span> of the Three Gorges Reservoir, China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tang, Qiang; Bao, Yuhai; He, Xiubin; Fu, Bojie; Collins, Adrian L; Zhang, Xinbao</p> <p>2016-04-01</p> <p>Since the launch of the Three Gorges Dam on the Yangtze River, a distinctive reservoir fluctuation <span class="hlt">zone</span> has been created and significantly modified by regular dam operations. Sediment redistribution within this artificial landscape differs substantially from that in natural fluvial riparian <span class="hlt">zones</span>, due to a specific hydrological regime comprising steps of water impoundment with increasing magnitudes and <span class="hlt">seasonal</span> water level fluctuation holding a range of sediment fluxes. This study reinterpreted post-dam sedimentary dynamics in the reservoir fluctuation <span class="hlt">zone</span> by stratigraphy determination of a 345-cm long sediment core, and related it to impact of the hydrological regime. <span class="hlt">Seasonality</span> in absolute grain-size composition of suspended sediment was applied as a methodological basis for stratigraphic differentiation. Sedimentary laminations with relatively higher proportions of sandy fractions were ascribed to sedimentation during the dry <span class="hlt">season</span> when proximal subsurface bank erosion dominates source contributions, while stratigraphy with a lower proportion of sandy fractions is possibly contributed by sedimentation during the wet <span class="hlt">season</span> when distal upstream surface erosion prevails. Chronology determination revealed non-linear and high annual sedimentation rates ranging from 21.7 to 152.1cm/yr. Although channel geomorphology may primarily determine the spatial extent of sedimentation, <span class="hlt">seasonal</span> sedimentary dynamics was predominantly governed by the frequency, magnitude, and duration of flooding. Summer inundation by natural floods with enhanced sediment loads produced from upstream basins induced higher sedimentation rates than water impoundment during the dry <span class="hlt">season</span> when distal sediment supply was limited. We thus conclude that flow regulation manipulates contemporary <span class="hlt">seasonal</span> sedimentary dynamics in the reservoir fluctuation <span class="hlt">zone</span>, though little impact on total sediment retention rate was detected. Ongoing reductions in flow and sediment supply under human disturbance may</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DSRI..101..110K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DSRI..101..110K"><span id="translatedtitle">Sinking particle flux in the sea <span class="hlt">ice</span> <span class="hlt">zone</span> of the Amundsen Shelf, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Minkyoung; Hwang, Jeomshik; Kim, Hyung J.; Kim, Dongseon; Yang, Eun J.; Ducklow, Hugh W.; Hyoung, S. La; Lee, Sang H.; Park, Jisoo; Lee, SangHoon</p> <p>2015-07-01</p> <p>We have examined the flux, biogenic composition, and isotopic values of sinking particles collected by a time-series sediment trap deployed in the sea <span class="hlt">ice</span> <span class="hlt">zone</span> (SIZ) of the Amundsen Sea from January 2011 for 1 year. The major portion of the particle flux occurred during the austral summer in January and February when sea <span class="hlt">ice</span> concentration was reduced to <60%. Biogenic components, dominated by opal (~78% of the biogenic components), accounted for over 75% of particle flux during this high-flux period. The dominant source of sinking particles shifted from diatoms to soft-tissued organisms, evidenced by high particulate organic carbon (POC) content (>30%) and a low bio-Si/POC ratio (<0.5) during the austral winter. CaCO3 content and its contribution to total particle flux was low (~6%) throughout the study period. Aged POC likely supplied from sediment resuspension accounted for a considerable fraction only from October to December, which was evidenced by a low radiocarbon content and relatively high (30-50%) content of the non-biogenic components. When compared with POC flux inside the Amundsen Sea polynya obtained by the US Amundsen Sea Polynya International Research Expedition (ASPIRE), the POC flux integrated over the austral summer in the SIZ was virtually identical, although the maximum POC flux was approximately half that inside the Amundsen Sea polynya. This comparatively high POC flux integrated over the austral summer in the SIZ may be caused by phytoplankton blooms persisting over a longer periods and more efficient export of organic matter potentially owing to the diatom-dominant plankton community. If this observation is a general phenomenon on the Amundsen Shelf, the role of the SIZ, compared with the polynyas, need to be examined more carefully when trying to characterize the POC export in this region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C13C..08K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C13C..08K"><span id="translatedtitle">Sinking Particle Flux in the Sea <span class="hlt">Ice</span> <span class="hlt">Zone</span> of the Amundsen Shelf, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, M.; Hwang, J.; Kim, H. J.; Kim, D.; Ducklow, H. W.; Lee, S. H.; Yang, E. J.; Lee, S.</p> <p>2014-12-01</p> <p>We have examined the flux, compositions of biogenic components, and isotopic values of sinking particles collected by a sediment trap deployed in the sea <span class="hlt">ice</span> <span class="hlt">zone</span> (SIZ) of the Amundsen Sea from January 2011 for one year. Major portion of the particle flux occurred during the austral summer in January and February when sea <span class="hlt">ice</span> concentration was reduced to below 60 %. Biogenic components, dominated by opal, accounted for over 75 % during this high flux period. The dominant source of sinking particles shifted from diatoms to soft-tissued organisms, evidenced by high particulate organic carbon (POC) content (> 30 %) during the polar night. CaCO3 content and its contribution to total particle flux were low throughout the study period. Contribution of aged POC likely supplied from sediment resuspension was considerable only from October to December, evidenced by low radiocarbon content and relatively high (30-50 %) content of the non-biogenic component. When compared to POC flux inside the Amundsen Sea polynya obtained by the US Amundsen Sea Polynya International Research Expedition (ASPIRE), the POC flux integrated over the austral summer in the SIZ was virtually identical although maximum POC flux was about half that inside the Amundsen Sea polynya. This comparatively high POC flux in the SIZ may be caused by persistence of phytoplankton bloom for longer period and more efficient export of organic matter owing to the diatom-dominant plankton community. If this observation is a general phenomenon on the Amundsen shelf, the role of the SIZ compared to the polynyas need to be examined more carefully when trying to characterize the POC export in this region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C13C0832R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C13C0832R"><span id="translatedtitle">Viable Particles from Iodine Compounds in the Antarctic Sea <span class="hlt">Ice</span> <span class="hlt">Zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roscoe, H. K.; Jones, A. E.; Brough, N.; Weller, R.; Saiz-Lopez, A.; Mahajan, A. S.; Schoenhardt, A.; Burrows, J. P.; Fleming, Z.</p> <p>2015-12-01</p> <p>Aerosol particle number concentrations have been measured at Halley and Neumayer on the Antarctic coast, since 2004 and 1984 respectively. Sulphur compounds known to be implicated in particle formation and growth were independently measured: sulphate ions and methane sulphonic acid in filtered aerosol samples; and gas-phase di-methyl sulphide for limited periods. Iodine oxide, IO, was determined by a satellite sensor from 2003 to 2009, and by different ground-based sensors at Halley in 2004 and in 2007. Previous model results and mid-latitude observations show that iodine compounds consistent with the large values of IO observed may be responsible for an increase in number concentrations of small particles. Coastal Antarctica is useful for investigating correlations between particles, sulphur and iodine compounds, because of their large annual cycles together with the source of iodine compounds in sea <span class="hlt">ice</span>. After smoothing all measured data by several days, the shapes of the annual cycles in particle concentration at Halley and at Neumayer are approximated by linear combinations of the shapes of sulphur compounds and IO, but not by sulphur compounds alone. However, there is no short-term correlation between IO and particle concentration. The apparent correlation after smoothing but not in the short term suggests that iodine compounds and particles are sourced some distance offshore. This suggests that new particles formed from iodine compounds are viable, i.e. they can last long enough to grow to the larger particles that contribute to Cloud Condensation Nuclei, rather than being adsorbed by existing particles. If so there is significant potential for climate feedback near the sea <span class="hlt">ice</span> <span class="hlt">zone</span> via the aerosol indirect effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..43.5233L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.5233L"><span id="translatedtitle">Arctic layer salinity controls heat loss from deep Atlantic layer in <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered areas of the Barents Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lind, Sigrid; Ingvaldsen, Randi B.; Furevik, Tore</p> <p>2016-05-01</p> <p>In the <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered northern Barents Sea an intermediate layer of cold and relatively fresh Arctic Water at ~25-110 m depth isolates the sea surface and <span class="hlt">ice</span> cover from a layer of warm and saline Atlantic Water below, a situation that resembles the cold halocline layer in the Eurasian Basin. The upward heat flux from the Atlantic layer is of major concern. What causes variations in the heat flux and how is the Arctic layer maintained? Using observations, we found that interannual variability in Arctic layer salinity determines the heat flux from the Atlantic layer through its control of stratification and vertical mixing. A relatively fresh Arctic layer effectively suppresses the upward heat flux, while a more saline Arctic layer enhances the heat flux. The corresponding upward salt flux causes a positive feedback. The Arctic layer salinity and the water column structures have been remarkably stable during 1970-2011.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JGR...10631447R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JGR...10631447R"><span id="translatedtitle"><span class="hlt">Seasonal</span> evolution of the mixed layer in the Subantarctic <span class="hlt">Zone</span> south of Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rintoul, Stephen R.; Trull, Thomas W.</p> <p>2001-12-01</p> <p>The circumpolar Subantarctic <span class="hlt">Zone</span> (SAZ) is a globally significant region of water mass formation and carbon dioxide uptake from the atmosphere. Here we synthesize the results of nine voyages over 8 years to describe the <span class="hlt">seasonal</span> variation in mixed layer properties in the SAZ south of Australia for comparison with biogeochemical process studies carried out in late summer (March 1998) as part of the SAZ Project. Winter mixing extends to depths >400 m, resulting in the formation of Subantarctic Mode Water. In summer the mixed layer shoals to 75-100 m, depths which are still sufficiently deep that phytoplankton growth may be light limited. Nitrate and phosphate concentrations are reduced in summer (e.g., nitrate decreases from >15 to <5 μmol kg-1) but remain well above limiting levels. Silicate, in contrast, is low throughout the year (4 μmol kg-1 in winter and <2 μmol kg-1 in summer). Water mass properties along a north-south hydrographic section in March 1998 suggest that near-surface waters spread from south to north across the Subantarctic Front (SAF), supplying cool, fresh, nutrient-rich water to the SAZ. As a consequence, the properties of the southern SAZ differ from those farther north: the mixed layer in the south is cooler, fresher, deeper, higher in nutrients, and bounded below by a halocline (rather than by a <span class="hlt">seasonal</span> thermocline, as in the northern SAZ). The contrast between the northern and southern SAZ persists throughout the year, suggesting the cross-front exchange occurs year-round and likely contributes to the differences in <span class="hlt">seasonal</span> thermal amplitude and algal biomass accumulation seen in satellite images. Density-compensated horizontal gradients of temperature and salinity are common in the mixed layer of the SAZ and the northern SAF, consistent with the hypothesis that the vigor of lateral mixing in the mixed layer is a strong function of the magnitude of the lateral density gradient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26551588','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26551588"><span id="translatedtitle">Soil radon dynamics in the Amer fault <span class="hlt">zone</span>: An example of very high <span class="hlt">seasonal</span> variations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Moreno, V; Bach, J; Font, Ll; Baixeras, C; Zarroca, M; Linares, R; Roqué, C</p> <p>2016-01-01</p> <p>Soil radon levels of the Amer fault <span class="hlt">zone</span> have been measured for a 4 year-period with the aim of checking <span class="hlt">seasonal</span> fluctuations obtained in previous studies and to understand radon origin and dynamics. In this manuscript additional results are presented: updated continuous and integrated soil radon measurements, radionuclide content of soil materials and a detailed analysis of an urban profile by means of the electrical resistivity imaging technique and punctual soil radon, thoron and CO2 measurements. Integrated and continuous measurements present a wide range of values, [0.2-151.6] kBq m(-3) for radon, [4.5-39.6] kBq m(-3) for thoron and [4.0-71.2] g m(-2) day(-1) for CO2. The highest soil radon levels in the vicinity of the Amer fault (>40 kBq m(-3)) are found close to the fractured areas and present very important fluctuations repeated every year, with values in summer much higher than in winter, confirming previous studies. The highest radon values, up to 150 kBq m(-3), do not have a local origin because the mean value of radium concentration in this soil (19 ± 5 Bq kg(-1)) could not explain these values. Then soil radon migration through the fractures, influenced by atmospheric parameters, is assumed to account for such a high <span class="hlt">seasonal</span> fluctuation. As main conclusion, in fractured areas, <span class="hlt">seasonal</span> variations of soil radon concentration can be very important even in places where average soil radon concentration and radium content are not especially high. In these cases the migration capability of the soil is given not by intrinsic permeability but by the fracture structure. Potential risk estimation based on soil radon concentration and intrinsic permeability must be complemented with geological information in fractured systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H53G1743G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H53G1743G"><span id="translatedtitle">Mapping <span class="hlt">Seasonal</span> Evapotranspiration and Root <span class="hlt">Zone</span> Soil Moisture using a Hybrid Modeling Approach over Vineyards</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Geli, H. M. E.</p> <p>2015-12-01</p> <p>Estimates of actual crop evapotranspiration (ETa) at field scale over the growing <span class="hlt">season</span> are required for improving agricultural water management, particularly in water limited and drought prone regions. Remote sensing data from multiple platforms such as airborne and Landsat-based sensors can be used to provide these estimates. Combining these data with surface energy balance models can provide ETa estimates at sub- field scale as well as information on vegetation stress and soil moisture conditions. However, the temporal resolution of airborne and Landsat data does not allow for a continuous ETa monitoring over the course of the growing <span class="hlt">season</span>. This study presents the application of a hybrid ETa modeling approach developed for monitoring daily ETa and root <span class="hlt">zone</span> available water at high spatial resolutions. The hybrid ETa modeling approach couples a thermal-based energy balance model with a water balance-based scheme using data assimilation. The two source energy balance (TSEB) model is used to estimate instantaneous ETa which can be extrapolated to daily ETa using a water balance model modified to use the reflectance-based basal crop coefficient for interpolating ETa in between airborne and/or Landsat overpass dates. Moreover, since it is a water balance model, the soil moisture profile is also estimated. The hybrid ETa approach is applied over vineyard fields in central California. High resolution airborne and Landsat imagery were used to drive the hybrid model. These images were collected during periods that represented different vine phonological stages in 2013 growing <span class="hlt">season</span>. Estimates of daily ETa and surface energy balance fluxes will be compared with ground-based eddy covariance tower measurements. Estimates of soil moisture at multiple depths will be compared with measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26551588','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26551588"><span id="translatedtitle">Soil radon dynamics in the Amer fault <span class="hlt">zone</span>: An example of very high <span class="hlt">seasonal</span> variations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Moreno, V; Bach, J; Font, Ll; Baixeras, C; Zarroca, M; Linares, R; Roqué, C</p> <p>2016-01-01</p> <p>Soil radon levels of the Amer fault <span class="hlt">zone</span> have been measured for a 4 year-period with the aim of checking <span class="hlt">seasonal</span> fluctuations obtained in previous studies and to understand radon origin and dynamics. In this manuscript additional results are presented: updated continuous and integrated soil radon measurements, radionuclide content of soil materials and a detailed analysis of an urban profile by means of the electrical resistivity imaging technique and punctual soil radon, thoron and CO2 measurements. Integrated and continuous measurements present a wide range of values, [0.2-151.6] kBq m(-3) for radon, [4.5-39.6] kBq m(-3) for thoron and [4.0-71.2] g m(-2) day(-1) for CO2. The highest soil radon levels in the vicinity of the Amer fault (>40 kBq m(-3)) are found close to the fractured areas and present very important fluctuations repeated every year, with values in summer much higher than in winter, confirming previous studies. The highest radon values, up to 150 kBq m(-3), do not have a local origin because the mean value of radium concentration in this soil (19 ± 5 Bq kg(-1)) could not explain these values. Then soil radon migration through the fractures, influenced by atmospheric parameters, is assumed to account for such a high <span class="hlt">seasonal</span> fluctuation. As main conclusion, in fractured areas, <span class="hlt">seasonal</span> variations of soil radon concentration can be very important even in places where average soil radon concentration and radium content are not especially high. In these cases the migration capability of the soil is given not by intrinsic permeability but by the fracture structure. Potential risk estimation based on soil radon concentration and intrinsic permeability must be complemented with geological information in fractured systems. PMID:26551588</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2596265','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2596265"><span id="translatedtitle">Geographic, <span class="hlt">seasonal</span>, and precipitation chemistry influence on the abundance and activity of biological <span class="hlt">ice</span> nucleators in rain and snow</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Christner, Brent C.; Cai, Rongman; Morris, Cindy E.; McCarter, Kevin S.; Foreman, Christine M.; Skidmore, Mark L.; Montross, Scott N.; Sands, David C.</p> <p>2008-01-01</p> <p>Biological <span class="hlt">ice</span> nucleators (IN) function as catalysts for freezing at relatively warm temperatures (warmer than −10 °C). We examined the concentration (per volume of liquid) and nature of IN in precipitation collected from Montana and Louisiana, the Alps and Pyrenees (France), Ross Island (Antarctica), and Yukon (Canada). The temperature of detectable <span class="hlt">ice</span>-nucleating activity for more than half of the samples was ≥ −5 °C based on immersion freezing testing. Digestion of the samples with lysozyme (i.e., to hydrolyze bacterial cell walls) led to reductions in the frequency of freezing (0–100%); heat treatment greatly reduced (95% average) or completely eliminated <span class="hlt">ice</span> nucleation at the measured conditions in every sample. These behaviors were consistent with the activity being bacterial and/or proteinaceous in origin. Statistical analysis revealed <span class="hlt">seasonal</span> similarities between warm-temperature <span class="hlt">ice</span>-nucleating activities in snow samples collected over 7 months in Montana. Multiple regression was used to construct models with biogeochemical data [major ions, total organic carbon (TOC), particle, and cell concentration] that were accurate in predicting the concentration of microbial cells and biological IN in precipitation based on the concentration of TOC, Ca2+, and NH4+, or TOC, cells, Ca2+, NH4+, K+, PO43−, SO42−, Cl−, and HCO3−. Our results indicate that biological IN are ubiquitous in precipitation and that for some geographic locations the activity and concentration of these particles is related to the <span class="hlt">season</span> and precipitation chemistry. Thus, our research suggests that biological IN are widespread in the atmosphere and may affect meteorological processes that lead to precipitation. PMID:19028877</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014WRR....50.9432V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014WRR....50.9432V"><span id="translatedtitle">Root <span class="hlt">zone</span> salinity and sodicity under <span class="hlt">seasonal</span> rainfall due to feedback of decreasing hydraulic conductivity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van der Zee, S. E. A. T. M.; Shah, S. H. H.; Vervoort, R. W.</p> <p>2014-12-01</p> <p>Soil sodicity, where the soil cation exchange complex is occupied for a significant fraction by Na+, may lead to vulnerability to soil structure deterioration. With a root <span class="hlt">zone</span> flow and salt transport model, we modeled the feedback effects of salt concentration (C) and exchangeable sodium percentage (ESP) on saturated hydraulic conductivity Ks(C, ESP) for different groundwater depths and climates, using the functional approach of McNeal (1968). We assume that a decrease of Ks is practically irreversible at a time scale of decades. Representing climate with a Poisson rainfall process, the feedback hardly affects salt and sodium accumulation compared with the case that feedback is ignored. However, if salinity decreases, the much more buffered ESP stays at elevated values, while Ks decreases. This situation may develop if rainfall has a <span class="hlt">seasonal</span> pattern where drought periods with accumulation of salts in the root <span class="hlt">zone</span> alternate with wet rainfall periods in which salts are leached. Feedback that affects both drainage/leaching and capillary upward flow from groundwater, or only drainage, leads to opposing effects. If both fluxes are affected by sodicity-induced degradation, this leads to reduced salinity (C) and sodicity (ESP), which suggests that the system dynamics and feedback oppose further degradation. Experiences in the field point in the same direction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110005552','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110005552"><span id="translatedtitle">ICESat Observations of <span class="hlt">Seasonal</span> and Interannual Variations of Sea-<span class="hlt">Ice</span> Freeboard and Estimated Thickness in the Weddell Sea, Antarctica (2003-2009)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yi, Donghui; Robbins, John W.</p> <p>2010-01-01</p> <p>Sea-<span class="hlt">ice</span> freeboard heights for 17 ICESat campaign periods from 2003 to 2009 are derived from ICESat data. Freeboard is combined with snow depth from Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) data and nominal densities of snow, water and sea <span class="hlt">ice</span>, to estimate sea-<span class="hlt">ice</span> thickness. Sea-<span class="hlt">ice</span> freeboard and thickness distributions show clear <span class="hlt">seasonal</span> variations that reflect the yearly cycle of growth and decay of the Weddell Sea (Antarctica) pack <span class="hlt">ice</span>. During October-November, sea <span class="hlt">ice</span> grows to its <span class="hlt">seasonal</span> maximum both in area and thickness; the mean freeboards are 0.33-0.41 m and the mean thicknesses are 2.10-2.59 m. During February-March, thinner sea <span class="hlt">ice</span> melts away and the sea-<span class="hlt">ice</span> pack is mainly distributed in the west Weddell Sea; the mean freeboards are 0.35-0.46 m and the mean thicknesses are 1.48-1.94 m. During May-June, the mean freeboards and thicknesses are 0.26-0.29 m and 1.32-1.37 m, respectively. The 6 year trends in sea-<span class="hlt">ice</span> extent and volume are (0.023+/-0.051) x 10(exp 6)sq km/a (0.45%/a) and (0.007+/-1.0.092) x 10(exp 3)cu km/a (0.08%/a); however, the large standard deviations indicate that these positive trends are not statistically significant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRC..117.0E04H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRC..117.0E04H"><span id="translatedtitle">Role of <span class="hlt">ice</span> dynamics in anomalous <span class="hlt">ice</span> conditions in the Beaufort Sea during 2006 and 2007</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hutchings, J. K.; Rigor, I. G.</p> <p>2012-05-01</p> <p>A new record minimum in summer sea <span class="hlt">ice</span> extent was set in 2007 and an unusual polynya formed in the Beaufort Sea <span class="hlt">ice</span> cover during the summer of 2006. Using a combination of visual observations from cruises, <span class="hlt">ice</span> drift, and satellite passive microwave sea <span class="hlt">ice</span> concentration, we show that <span class="hlt">ice</span> dynamics during preceding years included events that preconditioned the Beaufort <span class="hlt">ice</span> pack for the unusual patterns of opening observed in both summers. Intrusions of first year <span class="hlt">ice</span> from the Chukchi Sea to the Northern Beaufort, and increased pole-ward <span class="hlt">ice</span> transport from the western Arctic during summer has led to reduced replenishment of multiyear <span class="hlt">ice</span>, older than five years, in the western Beaufort, resulting in a younger, thinner <span class="hlt">ice</span> pack in most of the Beaufort. We find <span class="hlt">ice</span> younger than five years melts out completely by the end of summer, south of 76N. The 2006 unusual polynya was bounded to the south by an <span class="hlt">ice</span> tongue composed of sea <span class="hlt">ice</span> older than 5 years, and formed when first year and second year <span class="hlt">ice</span> melted between 76N and the older <span class="hlt">ice</span> to the south. In this paper we demonstrate that a recent shift in <span class="hlt">ice</span> circulation patterns in the western Arctic preconditions the Beaufort <span class="hlt">ice</span> pack for increased <span class="hlt">seasonal</span> <span class="hlt">ice</span> <span class="hlt">zone</span> extent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMOS11B1649M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMOS11B1649M"><span id="translatedtitle">Evolution of a Directional Wave Spectrum in a 3D Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> with Random Floe Size Distribution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Montiel, F.; Squire, V. A.</p> <p>2013-12-01</p> <p>A new ocean wave/sea-<span class="hlt">ice</span> interaction model is proposed that simulates how a directional wave spectrum evolves as it travels through a realistic marginal <span class="hlt">ice</span> <span class="hlt">zone</span> (MIZ), where wave/<span class="hlt">ice</span> dynamics are entirely governed by coherent conservative wave scattering effects. Field experiments conducted by Wadhams et al. (1986) in the Greenland Sea generated important data on wave attenuation in the MIZ and, particularly, on whether the wave spectrum spreads directionally or collimates with distance from the <span class="hlt">ice</span> edge. The data suggest that angular isotropy, arising from multiple scattering by <span class="hlt">ice</span> floes, occurs close to the edge and thenceforth dominates wave propagation throughout the MIZ. Although several attempts have been made to replicate this finding theoretically, including by the use of numerical models, none have confronted this problem in a 3D MIZ with fully randomised floe distribution properties. We construct such a model by subdividing the discontinuous <span class="hlt">ice</span> cover into adjacent infinite slabs of finite width parallel to the <span class="hlt">ice</span> edge. Each slab contains an arbitrary (but finite) number of circular <span class="hlt">ice</span> floes with randomly distributed properties. <span class="hlt">Ice</span> floes are modeled as thin elastic plates with uniform thickness and finite draught. We consider a directional wave spectrum with harmonic time dependence incident on the MIZ from the open ocean, defined as a continuous superposition of plane waves traveling at different angles. The scattering problem within each slab is then solved using Graf's interaction theory for an arbitrary incident directional plane wave spectrum. Using an appropriate integral representation of the Hankel function of the first kind (see Cincotti et al., 1993), we map the outgoing circular wave field from each floe on the slab boundaries into a directional spectrum of plane waves, which characterizes the slab reflected and transmitted fields. Discretizing the angular spectrum, we can obtain a scattering matrix for each slab. Standard recursive</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012LPI....43.1043M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012LPI....43.1043M"><span id="translatedtitle">Time Evolution and Inter-Annual Variability of <span class="hlt">Seasonal</span> <span class="hlt">Ice</span> on the Mars Northern Polar Cap</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mount, C.; Titus, T. N.</p> <p>2012-03-01</p> <p>We explore the temporal density variations of Mars' NPSC and use <span class="hlt">ice</span> depth and density estimates to constrain the CROCUS date for a specific location and compare it to the CROCUS dates from three previous Mars years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000JGR...10511889O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000JGR...10511889O"><span id="translatedtitle">Dynamics and energetics of the cloudy boundary layer in simulations of off-<span class="hlt">ice</span> flow in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olsson, Peter Q.; Harrington, Jerry Y.</p> <p>2000-05-01</p> <p>The case under consideration occurred on March 4, 1993, and was observed as part of the Radiation and Eddy Flux Experiment (REFLEX II) 1993 observational campaign northwest of Spitsbergen. The off-<span class="hlt">ice</span> flow on this day brought very cold surface air temperatures (-35°C) over a relatively warm ocean surface. The resultant latent and sensible surface heat fluxes produced intense convection and a thermal internal boundary layer (TIBL) which deepened with distance from the <span class="hlt">ice</span> edge. Two-dimensional cloud-resolving model (CRM) simulations were performed to determine the impact of various cloud parameterizations on the structure and evolution of the TIBL. The model was able to reproduce the observed thermal structure of the boundary layer to within the acknowledged limitations of the CRM approach. Sensitivity studies of cloud type showed that inclusion of mixed-phase microphysics had a large impact of BL depth and structure. Radiative heating of the cloud near cloud base and cooling near cloud top along with latent heat release were found to be significant sources of turbulence kinetic energy even in the present case where very strong surface heat fluxes occur. <span class="hlt">Ice</span>-phase precipitation processes rapidly depleted the BL of condensate, weakening the radiative thermal forcing. A further consequence of condensate depletion in the mixed-phase cloud was a less humid boundary layer that was able to maintain a larger surface latent heat flux and continuously extract heat through condensation and deposition. Not surprisingly, the presence of clouds had a profound impact on the radiative budget at the surface, with the cloudy BL reducing surface radiative losses more that 60% over clear-sky values. Inclusion of the <span class="hlt">ice</span> phase significantly affected the radiative budget as compared to purely liquid clouds, illustrating the importance of <span class="hlt">ice</span>-phase-radiative couplings for accurate simulations of arctic clouds and boundary layer dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016BGeo...13.4389V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016BGeo...13.4389V"><span id="translatedtitle"><span class="hlt">Seasonal</span> variability of the oxygen minimum <span class="hlt">zone</span> off Peru in a high-resolution regional coupled model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vergara, Oscar; Dewitte, Boris; Montes, Ivonne; Garçon, Veronique; Ramos, Marcel; Paulmier, Aurélien; Pizarro, Oscar</p> <p>2016-08-01</p> <p>In addition to being one of the most productive upwelling systems, the oceanic region off Peru is embedded in one of the most extensive oxygen minimum <span class="hlt">zones</span> (OMZs) of the world ocean. The dynamics of the OMZ off Peru remain uncertain, partly due to the scarcity of data and to the ubiquitous role of mesoscale activity on the circulation and biogeochemistry. Here we use a high-resolution coupled physical/biogeochemical model simulation to investigate the <span class="hlt">seasonal</span> variability of the OMZ off Peru. The focus is on characterizing the <span class="hlt">seasonal</span> cycle in dissolved O2 (DO) eddy flux at the OMZ boundaries, including the coastal domain, viewed here as the eastern boundary of the OMZ, considering that the mean DO eddy flux in these <span class="hlt">zones</span> has a significant contribution to the total DO flux. The results indicate that the <span class="hlt">seasonal</span> variations of the OMZ can be interpreted as resulting from the <span class="hlt">seasonal</span> modulation of the mesoscale activity. Along the coast, despite the increased <span class="hlt">seasonal</span> low DO water upwelling, the DO peaks homogeneously over the water column and within the Peru Undercurrent (PUC) in austral winter, which results from mixing associated with the increase in both the intraseasonal wind variability and baroclinic instability of the PUC. The coastal ocean acts therefore as a source of DO in austral winter for the OMZ core, through eddy-induced offshore transport that is also shown to peak in austral winter. In the open ocean, the OMZ can be divided vertically into two <span class="hlt">zones</span>: an upper <span class="hlt">zone</span> above 400 m, where the mean DO eddy flux is larger on average than the mean <span class="hlt">seasonal</span> DO flux and varies <span class="hlt">seasonally</span>, and a lower part, where the mean <span class="hlt">seasonal</span> DO flux exhibits vertical-zonal propagating features that share similar characteristics than those of the energy flux associated with the annual extratropical Rossby waves. At the OMZ meridional boundaries where the mean DO eddy flux is large, the DO eddy flux has also a marked <span class="hlt">seasonal</span> cycle that peaks in austral winter (spring</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008DSRII..55.2330T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008DSRII..55.2330T"><span id="translatedtitle">Pelagic and sympagic contribution of organic matter to zooplankton and vertical export in the Barents Sea marginal <span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tamelander, Tobias; Reigstad, Marit; Hop, Haakon; Carroll, Michael L.; Wassmann, Paul</p> <p>2008-10-01</p> <p> exported from the euphotic <span class="hlt">zone</span> was derived from pelagic primary production, but at 3 of 11 stations within the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> (MIZ), the <span class="hlt">ice</span> algal signal dominated the isotope composition of sinking material. The δ 13C of settling organic matter was positively related to the vertical flux of particulate organic carbon, with maximum values around -21‰ during the peak bloom phase. Sedimentation of isotopically light copepod faecal pellets (mean δ 13C -25.4‰) was reflected in a depletion of 13C in the sinking material. The results illustrate tight pelagic-benthic coupling in the Barents Sea MIZ through vertical export of fresh phytodetritus during phytoplankton blooms and episodic export of <span class="hlt">ice</span> algae.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol2/pdf/CFR-2013-title33-vol2-sec165-T11-568.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol2/pdf/CFR-2013-title33-vol2-sec165-T11-568.pdf"><span id="translatedtitle">33 CFR 165.T11-568 - Safety <span class="hlt">Zone</span>; San Diego Symphony Summer POPS Fireworks 2013 <span class="hlt">Season</span>, San Diego, CA.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>.... (1) In accordance with general regulations in 33 CFR Part 165, Subpart C, entry into, transit through... Summer POPS Fireworks 2013 <span class="hlt">Season</span>, San Diego, CA. 165.T11-568 Section 165.T11-568 Navigation and... Areas Eleventh Coast Guard District § 165.T11-568 Safety <span class="hlt">Zone</span>; San Diego Symphony Summer POPS...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9801D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9801D"><span id="translatedtitle">Model estimating the effect of marginal <span class="hlt">ice</span> <span class="hlt">zone</span> processes on the phytoplankton primary production and air-sea flux of CO2 in the Barents Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dvornikov, Anton; Sein, Dmitry; Ryabchenko, Vladimir; Gorchakov, Victor; Martjyanov, Stanislav</p> <p>2016-04-01</p> <p>This study is aimed to assess the impact of sea <span class="hlt">ice</span> on the primary production of phytoplankton (PPP) and air-sea CO2 flux in the Barents Sea. To get the estimations, we apply a three-dimensional eco-hydrodynamic model based on the Princeton Ocean Model which includes: 1) a module of sea <span class="hlt">ice</span> with 7 categories, and 2) the 11-component module of marine pelagic ecosystem developed in the St. Petersburg Branch, Institute of Oceanology. The model is driven by atmospheric forcing, prescribed from the reanalysis NCEP / NCAR, and conditions on the open sea boundary, prescribed from the regional model of the atmosphere-ocean-sea <span class="hlt">ice</span>-ocean biogeochemistry, developed at Max Planck Institute for Meteorology, Hamburg. Comparison of the model results for the period 1998-2007 with satellite data showed that the model reproduces the main features of the evolution of the sea surface temperature, <span class="hlt">seasonal</span> changes in the <span class="hlt">ice</span> extent, surface chlorophyll "a" concentration and PPP in the Barents Sea. Model estimates of the annual PPP for whole sea, APPmod, appeared in 1.5-2.3 times more than similar estimates, APPdata, from satellite data. The main reasons for this discrepancy are: 1) APPdata refers to the open water, while APPmod, to the whole sea area (under the pack <span class="hlt">ice</span> and marginal <span class="hlt">ice</span> <span class="hlt">zone</span> (MIZ) was produced 16 - 38% of PPP); and 2) values of APPdata are underestimated because of the subsurface chlorophyll maximum. During the period 1998-2007, the modelled maximal (in the <span class="hlt">seasonal</span> cycle) sea <span class="hlt">ice</span> area has decreased by 15%. This reduction was accompanied by an increase in annual PPP of the sea at 54 and 63%, based, respectively, on satellite data and the model for the open water. According to model calculations for the whole sea area, the increase is only 19%. Using a simple 7-component model of oceanic carbon cycle incorporated into the above hydrodynamic model, the CO2 exchange between the atmosphere and sea has been estimated in different conditions. In the absence of biological</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26849343','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26849343"><span id="translatedtitle">Modeling surface energy fluxes and thermal dynamics of a <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered hydroelectric reservoir.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Weifeng; Roulet, Nigel T; Strachan, Ian B; Tremblay, Alain</p> <p>2016-04-15</p> <p>The thermal dynamics of human created northern reservoirs (e.g., water temperatures and <span class="hlt">ice</span> cover dynamics) influence carbon processing and air-water gas exchange. Here, we developed a process-based one-dimensional model (Snow, <span class="hlt">Ice</span>, WAater, and Sediment: SIWAS) to simulate a full year's surface energy fluxes and thermal dynamics for a moderately large (>500km(2)) boreal hydroelectric reservoir in northern Quebec, Canada. There is a lack of climate and weather data for most of the Canadian boreal so we designed SIWAS with a minimum of inputs and with a daily time step. The modeled surface energy fluxes were consistent with six years of observations from eddy covariance measurements taken in the middle of the reservoir. The simulated water temperature profiles agreed well with observations from over 100 sites across the reservoir. The model successfully captured the observed annual trend of <span class="hlt">ice</span> cover timing, although the model overestimated the length of <span class="hlt">ice</span> cover period (15days). Sensitivity analysis revealed that air temperature significantly affects the <span class="hlt">ice</span> cover duration, water and sediment temperatures, but that dissolved organic carbon concentrations have little effect on the heat fluxes, and water and sediment temperatures. We conclude that the SIWAS model is capable of simulating surface energy fluxes and thermal dynamics for boreal reservoirs in regions where high temporal resolution climate data are not available. SIWAS is suitable for integration into biogeochemical models for simulating a reservoir's carbon cycle. PMID:26849343</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26849343','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26849343"><span id="translatedtitle">Modeling surface energy fluxes and thermal dynamics of a <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered hydroelectric reservoir.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Weifeng; Roulet, Nigel T; Strachan, Ian B; Tremblay, Alain</p> <p>2016-04-15</p> <p>The thermal dynamics of human created northern reservoirs (e.g., water temperatures and <span class="hlt">ice</span> cover dynamics) influence carbon processing and air-water gas exchange. Here, we developed a process-based one-dimensional model (Snow, <span class="hlt">Ice</span>, WAater, and Sediment: SIWAS) to simulate a full year's surface energy fluxes and thermal dynamics for a moderately large (>500km(2)) boreal hydroelectric reservoir in northern Quebec, Canada. There is a lack of climate and weather data for most of the Canadian boreal so we designed SIWAS with a minimum of inputs and with a daily time step. The modeled surface energy fluxes were consistent with six years of observations from eddy covariance measurements taken in the middle of the reservoir. The simulated water temperature profiles agreed well with observations from over 100 sites across the reservoir. The model successfully captured the observed annual trend of <span class="hlt">ice</span> cover timing, although the model overestimated the length of <span class="hlt">ice</span> cover period (15days). Sensitivity analysis revealed that air temperature significantly affects the <span class="hlt">ice</span> cover duration, water and sediment temperatures, but that dissolved organic carbon concentrations have little effect on the heat fluxes, and water and sediment temperatures. We conclude that the SIWAS model is capable of simulating surface energy fluxes and thermal dynamics for boreal reservoirs in regions where high temporal resolution climate data are not available. SIWAS is suitable for integration into biogeochemical models for simulating a reservoir's carbon cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20150023393&hterms=Sensitivity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DSensitivity','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20150023393&hterms=Sensitivity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DSensitivity"><span id="translatedtitle">Model Forecast Skill and Sensitivity to Initial Conditions in the <span class="hlt">Seasonal</span> Sea <span class="hlt">Ice</span> Outlook</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Blanchard-Wrigglesworth, E.; Cullather, R. I.; Wang, W.; Zhang, J.; Bitz, C. M.</p> <p>2015-01-01</p> <p>We explore the skill of predictions of September Arctic sea <span class="hlt">ice</span> extent from dynamical models participating in the Sea <span class="hlt">Ice</span> Outlook (SIO). Forecasts submitted in August, at roughly 2 month lead times, are skillful. However, skill is lower in forecasts submitted to SIO, which began in 2008, than in hindcasts (retrospective forecasts) of the last few decades. The multimodel mean SIO predictions offer slightly higher skill than the single-model SIO predictions, but neither beats a damped persistence forecast at longer than 2 month lead times. The models are largely unsuccessful at predicting each other, indicating a large difference in model physics and/or initial conditions. Motivated by this, we perform an initial condition sensitivity experiment with four SIO models, applying a fixed -1 m perturbation to the initial sea <span class="hlt">ice</span> thickness. The significant range of the response among the models suggests that different model physics make a significant contribution to forecast uncertainty.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26858575','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26858575"><span id="translatedtitle">Influence of <span class="hlt">season</span> on daytime behavioral activities of donkeys in the Northern Guinea Savanna <span class="hlt">zone</span> of Nigeria.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zakari, Friday Ocheja; Ayo, Joseph Olusegun; Rekwot, Peter Ibrahim; Kawu, Mohammed Umar</p> <p>2015-01-01</p> <p>The present experiment was performed with the aim of investigating the effect of <span class="hlt">season</span> on behavioral activities of donkeys during the rainy and harmattan <span class="hlt">seasons</span> in the Northern Guinea <span class="hlt">zone</span> of Nigeria. Sixteen apparently healthy donkeys were used as subjects and divided into four groups based on age. During each <span class="hlt">season</span>, behavioral activities of each donkey were evaluated for three weeks using the focal animal sampling technique. The dry-bulb temperature (DBT), relative humidity (RH), and temperature-humidity index (THI) were obtained three times each day during the experimental period using standard procedures. In the rainy <span class="hlt">season</span>, the mean DBT (31.65 ± 0.49°C), RH (73.63 ± 1.09%), and THI (84.39 ± 0.71) were significantly (P<0.0001) higher than the corresponding values of 24.00 ± 0.44°C, 36.80 ± 0.92%, and 64.80 ± 0.62 in the harmattan <span class="hlt">season</span>. During the rainy <span class="hlt">season</span>, the donkeys spent 60.00 ± 0.77%, 25.40 ± 0.69%, and 2.94 ± 0.21% on grazing, resting, and grooming, respectively. During the harmattan <span class="hlt">season</span>, the donkeys spent the most time on grazing (76.76 ± 0.43%), less time on resting (11.97 ± 0.38%), and the least time on grooming (0.89 ± 0.05%). In conclusion, <span class="hlt">season</span> and <span class="hlt">seasonal</span> variations affect the daytime behavioral activities of donkeys in the <span class="hlt">zone</span>, and this should be considered in husbandry practices for donkeys. PMID:26858575</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26858575','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26858575"><span id="translatedtitle">Influence of <span class="hlt">season</span> on daytime behavioral activities of donkeys in the Northern Guinea Savanna <span class="hlt">zone</span> of Nigeria.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zakari, Friday Ocheja; Ayo, Joseph Olusegun; Rekwot, Peter Ibrahim; Kawu, Mohammed Umar</p> <p>2015-01-01</p> <p>The present experiment was performed with the aim of investigating the effect of <span class="hlt">season</span> on behavioral activities of donkeys during the rainy and harmattan <span class="hlt">seasons</span> in the Northern Guinea <span class="hlt">zone</span> of Nigeria. Sixteen apparently healthy donkeys were used as subjects and divided into four groups based on age. During each <span class="hlt">season</span>, behavioral activities of each donkey were evaluated for three weeks using the focal animal sampling technique. The dry-bulb temperature (DBT), relative humidity (RH), and temperature-humidity index (THI) were obtained three times each day during the experimental period using standard procedures. In the rainy <span class="hlt">season</span>, the mean DBT (31.65 ± 0.49°C), RH (73.63 ± 1.09%), and THI (84.39 ± 0.71) were significantly (P<0.0001) higher than the corresponding values of 24.00 ± 0.44°C, 36.80 ± 0.92%, and 64.80 ± 0.62 in the harmattan <span class="hlt">season</span>. During the rainy <span class="hlt">season</span>, the donkeys spent 60.00 ± 0.77%, 25.40 ± 0.69%, and 2.94 ± 0.21% on grazing, resting, and grooming, respectively. During the harmattan <span class="hlt">season</span>, the donkeys spent the most time on grazing (76.76 ± 0.43%), less time on resting (11.97 ± 0.38%), and the least time on grooming (0.89 ± 0.05%). In conclusion, <span class="hlt">season</span> and <span class="hlt">seasonal</span> variations affect the daytime behavioral activities of donkeys in the <span class="hlt">zone</span>, and this should be considered in husbandry practices for donkeys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4739140','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4739140"><span id="translatedtitle">Influence of <span class="hlt">season</span> on daytime behavioral activities of donkeys in the Northern Guinea Savanna <span class="hlt">zone</span> of Nigeria</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>ZAKARI, Friday Ocheja; AYO, Joseph Olusegun; REKWOT, Peter Ibrahim; KAWU, Mohammed Umar</p> <p>2016-01-01</p> <p>ABSTRACT The present experiment was performed with the aim of investigating the effect of <span class="hlt">season</span> on behavioral activities of donkeys during the rainy and harmattan <span class="hlt">seasons</span> in the Northern Guinea <span class="hlt">zone</span> of Nigeria. Sixteen apparently healthy donkeys were used as subjects and divided into four groups based on age. During each <span class="hlt">season</span>, behavioral activities of each donkey were evaluated for three weeks using the focal animal sampling technique. The dry-bulb temperature (DBT), relative humidity (RH), and temperature-humidity index (THI) were obtained three times each day during the experimental period using standard procedures. In the rainy <span class="hlt">season</span>, the mean DBT (31.65 ± 0.49°C), RH (73.63 ± 1.09%), and THI (84.39 ± 0.71) were significantly (P<0.0001) higher than the corresponding values of 24.00 ± 0.44°C, 36.80 ± 0.92%, and 64.80 ± 0.62 in the harmattan <span class="hlt">season</span>. During the rainy <span class="hlt">season</span>, the donkeys spent 60.00 ± 0.77%, 25.40 ± 0.69%, and 2.94 ± 0.21% on grazing, resting, and grooming, respectively. During the harmattan <span class="hlt">season</span>, the donkeys spent the most time on grazing (76.76 ± 0.43%), less time on resting (11.97 ± 0.38%), and the least time on grooming (0.89 ± 0.05%). In conclusion, <span class="hlt">season</span> and <span class="hlt">seasonal</span> variations affect the daytime behavioral activities of donkeys in the <span class="hlt">zone</span>, and this should be considered in husbandry practices for donkeys. PMID:26858575</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.C33B0733M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.C33B0733M"><span id="translatedtitle">Subpixel variability of MODIS albedo retrievals and its importance for <span class="hlt">ice</span> sheet surface melting in southwestern Greenland's ablation <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moustafa, S.; Rennermalm, A. K.; Roman, M. O.; Koenig, L.; Smith, L. C.; Schaaf, C.; Wang, Z.; Mioduszewski, J.</p> <p>2013-12-01</p> <p>On the Greenland <span class="hlt">ice</span> sheet, albedo declined across 70% of its surface since 2000, with the greatest reduction in the lower 600 m of the southwestern ablation <span class="hlt">zone</span>. Because albedo plays a prominent role in the <span class="hlt">ice</span> sheet surface energy balance, its decline has resulted in near doubling of meltwater production. To characterize <span class="hlt">ice</span> sheet albedo, Moderate Imaging Spectrometer (MODIS) surface albedo products are typically used. However, it is unclear how the spatial variability of albedo within a MODIS pixel influences surface melting and whether it can be considered a linear function of albedo. In this study, high spatiotemporal resolution measurements of spectral albedo and <span class="hlt">ice</span> sheet surface ablation were collected along a ~ 1.3 km transect during June 2013 within the Akuliarusiarsuup Kuua (AK) River watershed in southwest Greenland. Spectral measurements were made at 325-1075 nm using a Analytical Spectral Devices (ASD) spectroradiometer, fitted with a Remote Cosine Receptor (RCR). In situ albedo measurements are compared with the daily MODIS albedo product (MCD43A) to analyze how space, time, surface heterogeneity, atmospheric conditions, and solar zenith angle geometry govern albedo at different scales. Finally, analysis of sub-pixel albedo and ablation reveal its importance on meltwater production in the lower parts of the <span class="hlt">ice</span> sheet margin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.H44C..02T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.H44C..02T"><span id="translatedtitle"><span class="hlt">Seasonal</span> Variations in CO2 Efflux, Vadose <span class="hlt">Zone</span> Gas Concentrations, and Natural Attenuation Rates at a Crude Oil Spill Site</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trost, J.; Sihota, N.; Delin, G. N.; Warren, E.</p> <p>2014-12-01</p> <p>Accurate estimates of hydrocarbon source <span class="hlt">zone</span> natural attenuation (SZNA) rates are important for managing contaminated sites but are difficult to measure. Moreover, SZNA rates may vary <span class="hlt">seasonally</span> in response to climatic conditions. Previous research at a crude oil spill site near Bemidji, Minnesota, USA showed that SZNA rates in the summer can be estimated by subtracting background soil CO2 efflux from the total soil CO2 efflux above the contaminated source. In this study, <span class="hlt">seasonal</span> variations in surficial CO2 efflux were evaluated with measurements of gas concentrations (including 14CO2), temperature, and volumetric water content in the vadose <span class="hlt">zone</span> at the site during a 2-year period. Soil CO2 effluxes in the source <span class="hlt">zone</span> were consistently greater than background CO2 effluxes, and the magnitude and areal extent of the increased efflux varied <span class="hlt">seasonally</span>. In the source <span class="hlt">zone</span>, the 14CO2 and the CO2 efflux data showed a larger proportion of soil CO2 was derived from SZNA in fall and winter (October - February) compared to the summer (June - August). Surficial CO2 effluxes and vadose <span class="hlt">zone</span> CO2 and CH4 concentrations in the source (2 - 7 meters below land surface) were positively correlated with soil temperature, indicating <span class="hlt">seasonal</span> variability in SZNA rates. However, peak surficial CO2 effluxes did not correspond with periods of highest CO2 or CH4 concentrations at the 2 - 7 meter depth, demonstrating the effects of physical attributes (such as soil depth, frost, and volumetric water content) on gas transport. Overall, results showed that SZNA rates, background soil respiration rates, and gas transport varied <span class="hlt">seasonally</span>, and that biological and physical factors are important to consider for accurately estimating SZNA rates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ESASP.734...60J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ESASP.734...60J"><span id="translatedtitle">Pros and Cons of Physical/Empirical SAR Altimetry Retracking in <span class="hlt">Seasonally</span> <span class="hlt">Ice</span>-Covered Waters in Preparation for Sentinel-3</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jain, Maulik; Andersen, Ole Baltazar; Stenseng, Lars</p> <p>2015-12-01</p> <p>An investigation is performed into the retrieval of sea surface heights in the Arctic Ocean to evaluate the determination of <span class="hlt">seasonal</span> sea level in the Arctic Ocean from satellite altimetry. Physical retrackers assume a uniform probability density function for the wave height within the footprint which is frequently compromised in the Arctic Ocean due to the presence of <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> and the period of initial freezing of the ocean. Preliminary investigations highlight the pros of the empirical retrackers for <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> covered regions as it does not assume anything about physical properties and the pros of a physical retracker for either permanent near fully <span class="hlt">ice</span> covered or open ocean. Comparison with tide gauge data is performed in this study to highlight the pros and cons of physical and empirical retracking in the Arctic Ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol2/pdf/CFR-2013-title33-vol2-sec165-T11-560.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol2/pdf/CFR-2013-title33-vol2-sec165-T11-560.pdf"><span id="translatedtitle">33 CFR 165.T11-560 - Safety <span class="hlt">Zone</span>; Sea World San Diego Fireworks 2013 <span class="hlt">Season</span>, Mission Bay; San Diego, CA.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... regulations in 33 CFR part 165, Subpart C, entry into, transit through or anchoring within this safety <span class="hlt">zone</span> is... Fireworks 2013 <span class="hlt">Season</span>, Mission Bay; San Diego, CA. 165.T11-560 Section 165.T11-560 Navigation and Navigable... Eleventh Coast Guard District § 165.T11-560 Safety <span class="hlt">Zone</span>; Sea World San Diego Fireworks 2013 <span class="hlt">Season</span>,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010E%26PSL.297..226L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010E%26PSL.297..226L"><span id="translatedtitle">CO 2 and O 2/N 2 variations in and just below the bubble-clathrate transformation <span class="hlt">zone</span> of Antarctic <span class="hlt">ice</span> cores</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lüthi, Dieter; Bereiter, Bernhard; Stauffer, Bernhard; Winkler, Renato; Schwander, Jakob; Kindler, Philippe; Leuenberger, Markus; Kipfstuhl, Sepp; Capron, Emilie; Landais, Amaelle; Fischer, Hubertus; Stocker, Thomas F.</p> <p>2010-08-01</p> <p>CO 2 measurements on the EPICA (European Project for <span class="hlt">Ice</span> Coring in Antarctica) DML <span class="hlt">ice</span> core in depth levels just below the bubble <span class="hlt">ice</span>-clathrate <span class="hlt">ice</span> transformation <span class="hlt">zone</span> (1230-2240 m depth) were performed. In the youngest part (1230-1600 m), they reveal variations of up to 25 ppmv around the mean atmospheric concentration within centimetres, corresponding to a snow deposition interval of a few years. Similar results are found at corresponding depth regions of the Dome C and the Talos Dome <span class="hlt">ice</span> cores. Since we can exclude all hitherto known processes altering the concentration of CO 2 in <span class="hlt">ice</span> cores, we present a hypothesis about spatial fractionation of air components related to episodically increasing clathrate formation followed by diffusion processes from bubbles to clathrates. This hypothesis is supported by optical line-scan observations and by O 2/N 2 measurements at the same depth where strong CO 2 variations are detected. Below the clathrate formation <span class="hlt">zone</span>, this small-scale fractionation process is slowly smoothed out, most likely by diffusion, regaining the initial mean atmospheric concentration. Although this process compromises the representativeness of a single CO 2 measurement on small <span class="hlt">ice</span> samples in the clathrate formation <span class="hlt">zone</span> of an <span class="hlt">ice</span> core, it does not affect the mean atmospheric CO 2 concentration if CO 2 values are averaged over a sufficiently long depth scale (> 10 cm in case of the EPICA DML <span class="hlt">ice</span> core).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JMS...154..192W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JMS...154..192W"><span id="translatedtitle"><span class="hlt">Seasonality</span> of vertical flux and sinking particle characteristics in an <span class="hlt">ice</span>-free high arctic fjord-Different from subarctic fjords?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wiedmann, Ingrid; Reigstad, Marit; Marquardt, Miriam; Vader, Anna; Gabrielsen, Tove M.</p> <p>2016-02-01</p> <p>The arctic Adventfjorden (78°N, 15°E, Svalbard) used to be <span class="hlt">seasonally</span> <span class="hlt">ice</span>-covered but has mostly been <span class="hlt">ice</span>-free since 2007. We used this <span class="hlt">ice</span>-free arctic fjord as a model area to investigate (1) how the vertical flux of biomass (chlorophyll a and particulate organic carbon, POC) follows the <span class="hlt">seasonality</span> of suspended material, (2) how sinking particle characteristics change <span class="hlt">seasonally</span> and affect the vertical flux, and (3) if the vertical flux in the <span class="hlt">ice</span>-free arctic fjord with glacial runoff resembles the flux in subarctic <span class="hlt">ice</span>-free fjords. During seven field investigations (December 2011-September 2012), suspended biomass was determined (5, 15, 25, and 60 m), and short-term sediment traps were deployed (20, 30, 40, and 60 m), partly modified with gel-filled jars to study the size and frequency distribution of sinking particles. During winter, resuspension from the seafloor resulted in large, detrital sinking particles. Intense sedimentation of fresh biomass occurred during the spring bloom. The highest POC flux was found during autumn (770-1530 mg POC m- 2 d- 1), associated with sediment-loaded glacial runoff and high pteropod abundances. The vertical biomass flux in the <span class="hlt">ice</span>-free arctic Adventfjorden thus resembled that in subarctic fjords during winter and spring, but a higher POC sedimentation was observed during autumn.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DPS....4721020B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DPS....4721020B"><span id="translatedtitle">Modeling the <span class="hlt">seasonal</span> evolution of the surface distribution of N2, CH4 and CO <span class="hlt">ices</span> on Pluto to interpret New Horizons observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bertrand, Tanguy; Forget, François</p> <p>2015-11-01</p> <p>The distribution of nitrogen, methane and carbon monoxide <span class="hlt">ices</span> on Pluto as observed by New Horizons is controlled by the intense <span class="hlt">seasonal</span> cycle and possibly by some internal sources. To better understand the <span class="hlt">seasonal</span> processes, we have developed a detailed model of the <span class="hlt">ices</span> cycles derived from a full Global Climate Model (GCM, see Forget et al., this issue) but in which the transport by the atmosphere is parametrized, based on reference GCM simulations. This allows to simulate the <span class="hlt">seasonal</span> <span class="hlt">ices</span> cycles on Pluto for thousands of years.The resulting distribution primarily depends on the <span class="hlt">seasonal</span> thermal inertia used for the different <span class="hlt">ices</span>, and is affected by the assumed topography as well. As observed, it is possible to form permanent deposits in the equatorial regions, with possible longitudinal variations depending on the topography. In particular, we will discuss how the elevation of the anti-Charon point, which is not random since its location is the output of the Pluto-Charon tidal locking process, may explain the formation of the Tombaugh Regio <span class="hlt">ice</span> deposits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C11B0753A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C11B0753A"><span id="translatedtitle">Crevasses, Fractures and Folds within Firn and Marine <span class="hlt">Ice</span> of the McMurdo Shear <span class="hlt">Zone</span>, Antarctica interpreted from GPR Profiles acquired with an Unmanned Rover</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arcone, S. A.; Lever, J.; Ray, L.</p> <p>2015-12-01</p> <p>The firn of the McMurdo shear <span class="hlt">zone</span> within the Ross <span class="hlt">Ice</span> Shelf, Antarctica is intensively crevassed, and may also contain crevasses within its meteoric and marine <span class="hlt">ice</span>. However, the surface crevassing prevents ordinary vehicle access to investigate its structure geophysically. We used a lightweight robotic vehicle to tow 200 and 400 MHz ground-penetrating radar antennas simultaneously along 100 evenly spaced transects over a 28 km2 grid spanning the shear <span class="hlt">zone</span> width. Transects were mainly orthogonal to <span class="hlt">ice</span> flow. Total firn and meteoric <span class="hlt">ice</span> thickness was about 160 m. Firn crevasses profiled at 400 MHz were up to 16 m wide, under snow bridges up to 10 m thick, and with strikes near 50-55° to general flow direction. From top down, 200-MHz profiles reveal firn diffractions originating to about 40 m depth, no discernible structure within the meteoric <span class="hlt">ice</span>, a discontinuous transitional horizon, and at least 20 m of disturbed and stratified marine <span class="hlt">ice</span>. Freeboard ranging from 28-31 m shows more marine <span class="hlt">ice</span> exists. We interpret the transitional horizon to be a thin saline layer, and marine <span class="hlt">ice</span> hyperbolic diffractions and reflections to be responses to localized fractures and to crevasses of various widths, filled with unstratified marine <span class="hlt">ice</span>, and at strikes mainly between 41-63°. We interpret off-nadir, marine <span class="hlt">ice</span> horizons to be responses to linear and folded faults, the structure and orientation of which are similar to some in firn. The coinciding and synchronously folded areas of fractured firn and marine <span class="hlt">ice</span> suggest the visibly unstructured meteoric <span class="hlt">ice</span> is also fractured, but either never crevassed, or crevassed and sutured without sea water penetration, and that any bottom crevasses that occurred near grounding lines have been thermally eroded. Consequently any fractures in the meteoric <span class="hlt">ice</span> beneath our grid are likely to have formed far from any grounding area, but it is unclear why there is no evidence of sea water penetration given the fractured and crevassed marine <span class="hlt">ice</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22544639','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22544639"><span id="translatedtitle">The effect of substrate, <span class="hlt">season</span>, and agroecological <span class="hlt">zone</span> on mycoflora and aflatoxin contamination of poultry feed from Khyber Pakhtunkhwa, Pakistan.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Alam, Sahib; Shah, Hamid Ullah; Khan, Habibullah; Magan, Naresh</p> <p>2012-10-01</p> <p>To study the effects of and interactions among feed types, <span class="hlt">seasons</span>, and agroecological <span class="hlt">zones</span> on the total fungal viable count and aflatoxins B1 (AFB1), B2 (AFB2), G1 (AFG1), and G2 (AFG2) production in poultry feed, an experiment was conducted using three-factorial design. A total of 216 samples of poultry feed ingredients, viz. maize, wheat, rice, cotton seed meal (CSM), and finished products, that is, starter and finisher broilers' rations, were collected from Peshawar, Swat, and D. I. Khan districts of Khyber Pakhtunkhwa, Pakistan, during the winter, spring, summer, and autumn <span class="hlt">seasons</span> of the year 2007/2008. Analysis of variance showed that there was a complex interaction among all these factors and that this influenced the total fungal viable count and relative concentrations of the aflatoxins produced. Minimum total culturable fungi (6.43 × 10³ CFUs/g) were counted in CSM from D. I. Khan region in winter <span class="hlt">season</span> while maximum (26.68 × 10³ CFUs/g) in starter ration from Peshawar region in summer. Maximum concentrations of AFB1 (191.65 ng/g), AFB2 (86.85 ng/g), and AFG2 (89.90 ng/g) were examined during the summer <span class="hlt">season</span> whereas the concentration of AFG1 was maximum (167.82 ng/g) in autumn in finisher ration from Peshawar region. Minimum aflatoxins were produced in the winter <span class="hlt">season</span> across all the three agroecological <span class="hlt">zones</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23479891','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23479891"><span id="translatedtitle">[Distribution and <span class="hlt">seasonal</span> dynamics of meiofauna in intertidal <span class="hlt">zone</span> of Qingdao sandy beaches, Shandong Province of East China].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Ha; Hua, Er; Zhang, Zhi-Nan</p> <p>2012-12-01</p> <p>An investigation was conducted on the abundance, group composition, and distribution of meiofauna at the Second Beach of Taiping Bay and the Shilaoren Beach in Qingdao in January, April, July, and October 2008, aimed to analyze the distribution and <span class="hlt">seasonal</span> dynamics of meiofauna in the intertidal <span class="hlt">zone</span> of Qingdao sandy beaches. The measurements of environmental factors, including sediment grain size, interstitial water salinity, interstitial water temperature, organic matter content (TOC), and chlorophyll a (Chl a) content, were made simultaneously. There existed obvious <span class="hlt">seasonal</span> differences in the environment factors, which could be clustered into two groups, i. e. , spring-winter group (January and April) and summer-autumn group (July and October). At the Second Beach of Taiping Bay, the mean annual abundance of meiofauna was (1167.3 +/- 768.3) ind x 10 cm(-2), and the most dominant group was Nematoda, accounting for 91% of the total. The meiofaunal group composition and abundance at the Second Beach differed horizontally, with the abundance ranked as high tide <span class="hlt">zone</span> < middle tide <span class="hlt">zone</span> < low tide <span class="hlt">zone</span>. The meiofaunal group composition and abundance also varied <span class="hlt">seasonally</span>, with high values in spring/winter and low values in summer/autumn (spring > winter > autumn > summer). The vertical distribution of the meiofauna in the high and middle tide <span class="hlt">zones</span> of the Second Beach varied <span class="hlt">seasonally</span> too. The meiofauna migrated downward with increasing temperature, concentrated in surface layer in winter and migrated downward in summer. At the Shilaoren Beach, the mean annual abundance of meiofauna was (1130.2 +/- 1419.1) ind x 10 cm(-2), and Nematoda accounted for 85% of the total. There was a great similarity of the environmental factors in the middle tide <span class="hlt">zone</span> of the Second Beach and Shilaoren Beach, which led to no differences in the meiofaunal group composition and abundance. However, the vertical distribution of the meiofauna differed between the two beaches. When the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PrOce.136...50W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PrOce.136...50W"><span id="translatedtitle">Projected future duration of the sea-<span class="hlt">ice</span>-free <span class="hlt">season</span> in the Alaskan Arctic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Muyin; Overland, James E.</p> <p>2015-08-01</p> <p>Global warming and continued reduction in sea <span class="hlt">ice</span> cover will result in longer open water duration in the Arctic, which is important for the shipping industry, marine mammals, and other components of the regional ecosystem. In this study we assess the length of open water duration in the Alaskan Arctic over the next few decades using the set of latest coupled climate models (CMIP5). The Alaskan Arctic, including the Chukchi and the Beaufort Sea, has been a major region of summer sea <span class="hlt">ice</span> retreat since 2007. Thirty five climate models from CMIP5 are evaluated and twelve are selected for composite projections based on their historical simulation performance. In the regions north of the Bering Strait (north of 70° N), future open-water duration shifts from a current 3-4 months to a projected near 5 months by 2040 based on the mean of the twelve selected climate models. There is considerable north-south gradient in projected durations. Open water duration is about 1 month shorter along the same latitudes in the Beaufort Sea compared with that in the Chukchi Sea. Uncertainty is generally ±1 month estimated from the range of model results. Open-water duration in the Alaskan Arctic expands quickly in these models over the next decades which will impact regional economic access and potentially alter ecosystems. Yet the northern Alaskan Arctic from January through May will remain sea <span class="hlt">ice</span> covered into the second half of the century due to normal lack of sunlight.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ECSS..159...60A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ECSS..159...60A"><span id="translatedtitle">Hypoxia in the central Arabian Gulf Exclusive Economic <span class="hlt">Zone</span> (EEZ) of Qatar during summer <span class="hlt">season</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Al-Ansari, Ebrahim M. A. S.; Rowe, G.; Abdel-Moati, M. A. R.; Yigiterhan, O.; Al-Maslamani, I.; Al-Yafei, M. A.; Al-Shaikh, I.; Upstill-Goddard, R.</p> <p>2015-06-01</p> <p>One of the most fascinating and unexpected discoveries during the Qatar University Marine Expeditions to the marine Exclusive Economic <span class="hlt">Zone</span> (EEZ) of Qatar in 2000-2001, was the detection of a hypoxic water layer in the central region of the Arabian Gulf in waters deeper than 50 m. Hypoxia was defined as the region where the concentration of dissolved oxygen was less than 2 mg L-1. This article presents the discovery of hypoxia in the Arabian Gulf, based on samples collected (mainly during evening or night time) from vertical profiles along transects of the EEZ of Qatar and analyzed for physico-chemical properties, nutrients and chlorophyll-a. Hypoxia occurred in the summer months caused by an interaction between physical stratification of the water column that prevents oxygen replenishment, and biological respiration that consumes oxygen. Strong south-westerly winds (the SW monsoon) from June to September drive the relatively low-salinity nutrient-rich surface water from the Arabian Sea/Arabian Gulf (Sea of Oman) through the Strait of Hormuz into the central-Arabian Gulf, and this surface current penetration fertilizes the deep central-Arabian Gulf during the summer period. A strong <span class="hlt">seasonal</span> pycnocline is formed between deeper waters at an ambient temperature of 20.9 °C and surface waters at 31.9 °C. This prevents the mixing of supersaturated O2 (>100-130%) water from the upper layer that would otherwise raise concentrations of dissolved oxygen below the thermocline, thus resulting in deep water hypoxia, i.e. dissolved oxygen levels of less than 0.86 ml L-1 at 17.3% saturation. These are the lowest values ever recorded for the Arabian Gulf. The calculated area of hypoxia is around 7220 square kilometers, and occurs in a layer about ≥15 m thick above the sea floor which extends toward the deep part of the Qatar Exclusive Economic <span class="hlt">Zone</span> (EEZ). The biological consequences of this hypoxia on the sea floor are yet to be investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3797495','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3797495"><span id="translatedtitle">What to eat now? Shifts in polar bear diet during the <span class="hlt">ice</span>-free <span class="hlt">season</span> in western Hudson Bay</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gormezano, Linda J; Rockwell, Robert F</p> <p>2013-01-01</p> <p>Under current climate trends, spring <span class="hlt">ice</span> breakup in Hudson Bay is advancing rapidly, leaving polar bears (Ursus maritimus) less time to hunt seals during the spring when they accumulate the majority of their annual fat reserves. For this reason, foods that polar bears consume during the <span class="hlt">ice</span>-free <span class="hlt">season</span> may become increasingly important in alleviating nutritional stress from lost seal hunting opportunities. Defining how the terrestrial diet might have changed since the onset of rapid climate change is an important step in understanding how polar bears may be reacting to climate change. We characterized the current terrestrial diet of polar bears in western Hudson Bay by evaluating the contents of passively sampled scat and comparing it to a similar study conducted 40 years ago. While the two terrestrial diets broadly overlap, polar bears currently appear to be exploiting increasingly abundant resources such as caribou (Rangifer tarandus) and snow geese (Chen caerulescens caerulescens) and newly available resources such as eggs. This opportunistic shift is similar to the diet mixing strategy common among other Arctic predators and bear species. We discuss whether the observed diet shift is solely a response to a nutritional stress or is an expression of plastic foraging behavior. PMID:24223286</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23222446','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23222446"><span id="translatedtitle">Females roam while males patrol: divergence in breeding <span class="hlt">season</span> movements of pack-<span class="hlt">ice</span> polar bears (Ursus maritimus).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Laidre, Kristin L; Born, Erik W; Gurarie, Eliezer; Wiig, Øystein; Dietz, Rune; Stern, Harry</p> <p>2013-02-01</p> <p>Intraspecific differences in movement behaviour reflect different tactics used by individuals or sexes to favour strategies that maximize fitness. We report movement data collected from n = 23 adult male polar bears with novel ear-attached transmitters in two separate pack <span class="hlt">ice</span> subpopulations over five breeding <span class="hlt">seasons</span>. We compared movements with n = 26 concurrently tagged adult females, and analysed velocities, movement tortuosity, range sizes and habitat selection with respect to sex, reproductive status and body mass. There were no differences in 4-day displacements or sea <span class="hlt">ice</span> habitat selection for sex or population. By contrast, adult females in all years and both populations had significantly more linear movements and significantly larger breeding range sizes than males. We hypothesized that differences were related to encounter rates, and used observed movement metrics to parametrize a simulation model of male-male and male-female encounter. The simulation showed that the more tortuous movement of males leads to significantly longer times to male-male encounter, while having little impact on male-female encounter. By contrast, linear movements of females are consistent with a prioritized search for sparsely distributed prey. These results suggest a possible mechanism for explaining the smaller breeding range sizes of some solitary male carnivores compared to females. PMID:23222446</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24223286','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24223286"><span id="translatedtitle">What to eat now? Shifts in polar bear diet during the <span class="hlt">ice</span>-free <span class="hlt">season</span> in western Hudson Bay.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gormezano, Linda J; Rockwell, Robert F</p> <p>2013-09-01</p> <p>Under current climate trends, spring <span class="hlt">ice</span> breakup in Hudson Bay is advancing rapidly, leaving polar bears (Ursus maritimus) less time to hunt seals during the spring when they accumulate the majority of their annual fat reserves. For this reason, foods that polar bears consume during the <span class="hlt">ice</span>-free <span class="hlt">season</span> may become increasingly important in alleviating nutritional stress from lost seal hunting opportunities. Defining how the terrestrial diet might have changed since the onset of rapid climate change is an important step in understanding how polar bears may be reacting to climate change. We characterized the current terrestrial diet of polar bears in western Hudson Bay by evaluating the contents of passively sampled scat and comparing it to a similar study conducted 40 years ago. While the two terrestrial diets broadly overlap, polar bears currently appear to be exploiting increasingly abundant resources such as caribou (Rangifer tarandus) and snow geese (Chen caerulescens caerulescens) and newly available resources such as eggs. This opportunistic shift is similar to the diet mixing strategy common among other Arctic predators and bear species. We discuss whether the observed diet shift is solely a response to a nutritional stress or is an expression of plastic foraging behavior. PMID:24223286</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3574305','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3574305"><span id="translatedtitle">Females roam while males patrol: divergence in breeding <span class="hlt">season</span> movements of pack-<span class="hlt">ice</span> polar bears (Ursus maritimus)</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Laidre, Kristin L.; Born, Erik W.; Gurarie, Eliezer; Wiig, Øystein; Dietz, Rune; Stern, Harry</p> <p>2013-01-01</p> <p>Intraspecific differences in movement behaviour reflect different tactics used by individuals or sexes to favour strategies that maximize fitness. We report movement data collected from n = 23 adult male polar bears with novel ear-attached transmitters in two separate pack <span class="hlt">ice</span> subpopulations over five breeding <span class="hlt">seasons</span>. We compared movements with n = 26 concurrently tagged adult females, and analysed velocities, movement tortuosity, range sizes and habitat selection with respect to sex, reproductive status and body mass. There were no differences in 4-day displacements or sea <span class="hlt">ice</span> habitat selection for sex or population. By contrast, adult females in all years and both populations had significantly more linear movements and significantly larger breeding range sizes than males. We hypothesized that differences were related to encounter rates, and used observed movement metrics to parametrize a simulation model of male–male and male–female encounter. The simulation showed that the more tortuous movement of males leads to significantly longer times to male–male encounter, while having little impact on male–female encounter. By contrast, linear movements of females are consistent with a prioritized search for sparsely distributed prey. These results suggest a possible mechanism for explaining the smaller breeding range sizes of some solitary male carnivores compared to females. PMID:23222446</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24223286','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24223286"><span id="translatedtitle">What to eat now? Shifts in polar bear diet during the <span class="hlt">ice</span>-free <span class="hlt">season</span> in western Hudson Bay.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gormezano, Linda J; Rockwell, Robert F</p> <p>2013-09-01</p> <p>Under current climate trends, spring <span class="hlt">ice</span> breakup in Hudson Bay is advancing rapidly, leaving polar bears (Ursus maritimus) less time to hunt seals during the spring when they accumulate the majority of their annual fat reserves. For this reason, foods that polar bears consume during the <span class="hlt">ice</span>-free <span class="hlt">season</span> may become increasingly important in alleviating nutritional stress from lost seal hunting opportunities. Defining how the terrestrial diet might have changed since the onset of rapid climate change is an important step in understanding how polar bears may be reacting to climate change. We characterized the current terrestrial diet of polar bears in western Hudson Bay by evaluating the contents of passively sampled scat and comparing it to a similar study conducted 40 years ago. While the two terrestrial diets broadly overlap, polar bears currently appear to be exploiting increasingly abundant resources such as caribou (Rangifer tarandus) and snow geese (Chen caerulescens caerulescens) and newly available resources such as eggs. This opportunistic shift is similar to the diet mixing strategy common among other Arctic predators and bear species. We discuss whether the observed diet shift is solely a response to a nutritional stress or is an expression of plastic foraging behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23222446','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23222446"><span id="translatedtitle">Females roam while males patrol: divergence in breeding <span class="hlt">season</span> movements of pack-<span class="hlt">ice</span> polar bears (Ursus maritimus).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Laidre, Kristin L; Born, Erik W; Gurarie, Eliezer; Wiig, Øystein; Dietz, Rune; Stern, Harry</p> <p>2013-02-01</p> <p>Intraspecific differences in movement behaviour reflect different tactics used by individuals or sexes to favour strategies that maximize fitness. We report movement data collected from n = 23 adult male polar bears with novel ear-attached transmitters in two separate pack <span class="hlt">ice</span> subpopulations over five breeding <span class="hlt">seasons</span>. We compared movements with n = 26 concurrently tagged adult females, and analysed velocities, movement tortuosity, range sizes and habitat selection with respect to sex, reproductive status and body mass. There were no differences in 4-day displacements or sea <span class="hlt">ice</span> habitat selection for sex or population. By contrast, adult females in all years and both populations had significantly more linear movements and significantly larger breeding range sizes than males. We hypothesized that differences were related to encounter rates, and used observed movement metrics to parametrize a simulation model of male-male and male-female encounter. The simulation showed that the more tortuous movement of males leads to significantly longer times to male-male encounter, while having little impact on male-female encounter. By contrast, linear movements of females are consistent with a prioritized search for sparsely distributed prey. These results suggest a possible mechanism for explaining the smaller breeding range sizes of some solitary male carnivores compared to females.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988MarGR...9..265E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988MarGR...9..265E"><span id="translatedtitle">The <span class="hlt">ICE</span>-MOSES experiment: Mapping permafrost <span class="hlt">zones</span> electrically beneath the Beaufort Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Edwards, R. N.; Wolfgram, P. A.; Judge, A. S.</p> <p>1988-09-01</p> <p> highly variable. The resulting depth-averaged resistivity, the resistivity resolved by a surface electrical method, is macro-an-isotropic. An experimental design study reveals that both the vertical and horizontal averaged resistivities could be determined in a MOSES sounding without vertical scale distortion. A test of the methodology in very shallow water was conducted in the spring of 1986 at a site, approximate coordinates (70° N, 134.5° W), 85 km north-west of the town of Tuktoyaktuk. The instrumentation was lowered and subsequently recovered through holes in the <span class="hlt">ice</span> which covers the Beaufort Sea at that time of the year. The transmitter power was obtained from a single lead-acid battery. Transmitter-receiver separations ranged from 10 to 300 m. A rapid increase in sediment resistivity with depth was observed. The higher resistivity values are consistent with those expected for a partially frozen <span class="hlt">zone</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20070016598&hterms=feedback&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dfeedback','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20070016598&hterms=feedback&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dfeedback"><span id="translatedtitle">Observational Evidence of a Hemispheric-wide <span class="hlt">Ice</span>-ocean Albedo Feedback Effect on Antarctic Sea-<span class="hlt">ice</span> Decay</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nihashi, Sohey; Cavalieri, Donald J.</p> <p>2007-01-01</p> <p>The effect of <span class="hlt">ice</span>-ocean albedo feedback (a kind of <span class="hlt">ice</span>-albedo feedback) on sea-<span class="hlt">ice</span> decay is demonstrated over the Antarctic sea-<span class="hlt">ice</span> <span class="hlt">zone</span> from an analysis of satellite-derived hemispheric sea <span class="hlt">ice</span> concentration and European Centre for Medium-Range Weather Forecasts (ERA-40) atmospheric data for the period 1979-2001. Sea <span class="hlt">ice</span> concentration in December (time of most active melt) correlates better with the meridional component of the wind-forced <span class="hlt">ice</span> drift (MID) in November (beginning of the melt <span class="hlt">season</span>) than the MID in December. This 1 month lagged correlation is observed in most of the Antarctic sea-<span class="hlt">ice</span> covered ocean. Daily time series of <span class="hlt">ice</span> , concentration show that the <span class="hlt">ice</span> concentration anomaly increases toward the time of maximum sea-<span class="hlt">ice</span> melt. These findings can be explained by the following positive feedback effect: once <span class="hlt">ice</span> concentration decreases (increases) at the beginning of the melt <span class="hlt">season</span>, solar heating of the upper ocean through the increased (decreased) open water fraction is enhanced (reduced), leading to (suppressing) a further decrease in <span class="hlt">ice</span> concentration by the oceanic heat. Results obtained fi-om a simple <span class="hlt">ice</span>-ocean coupled model also support our interpretation of the observational results. This positive feedback mechanism explains in part the large interannual variability of the sea-<span class="hlt">ice</span> cover in summer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27651063','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27651063"><span id="translatedtitle">Changes in the timing, length and heating degree days of the heating <span class="hlt">season</span> in central heating <span class="hlt">zone</span> of China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shen, Xiangjin; Liu, Binhui</p> <p>2016-09-21</p> <p>Climate change affects the demand for energy consumption, especially for heating and cooling buildings. Using daily mean temperature (Tmean) data, this study analyzed the spatiotemporal changes of the starting date for heating (HS), ending date for heating (HE), length (HL) and heating degree day (HDD) of the heating <span class="hlt">season</span> in central heating <span class="hlt">zone</span> of China. Over China's central heating <span class="hlt">zone</span>, regional average HS has become later by 0.97 day per decade and HE has become earlier by 1.49 days per decade during 1960-2011, resulting in a decline of HL (-2.47 days/decade). Regional averaged HDD decreased significantly by 63.22 °C/decade, which implies a decreasing energy demand for heating over the central heating <span class="hlt">zone</span> of China. Spatially, there are generally larger energy-saving rate in the south, due to low average HDD during the heating <span class="hlt">season</span>. Over China's central heating <span class="hlt">zone</span>, Tmean had a greater effect on HL in warm localities and a greater effect on HDD in cold localities. We project that the sensitivity of HL (HDD) to temperature change will increase (decrease) in a warmer climate. These opposite sensitivities should be considered when we want to predict the effects of climate change on heating energy consumption in China in the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5030661','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5030661"><span id="translatedtitle">Changes in the timing, length and heating degree days of the heating <span class="hlt">season</span> in central heating <span class="hlt">zone</span> of China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shen, Xiangjin; Liu, Binhui</p> <p>2016-01-01</p> <p>Climate change affects the demand for energy consumption, especially for heating and cooling buildings. Using daily mean temperature (Tmean) data, this study analyzed the spatiotemporal changes of the starting date for heating (HS), ending date for heating (HE), length (HL) and heating degree day (HDD) of the heating <span class="hlt">season</span> in central heating <span class="hlt">zone</span> of China. Over China’s central heating <span class="hlt">zone</span>, regional average HS has become later by 0.97 day per decade and HE has become earlier by 1.49 days per decade during 1960–2011, resulting in a decline of HL (−2.47 days/decade). Regional averaged HDD decreased significantly by 63.22 °C/decade, which implies a decreasing energy demand for heating over the central heating <span class="hlt">zone</span> of China. Spatially, there are generally larger energy-saving rate in the south, due to low average HDD during the heating <span class="hlt">season</span>. Over China’s central heating <span class="hlt">zone</span>, Tmean had a greater effect on HL in warm localities and a greater effect on HDD in cold localities. We project that the sensitivity of HL (HDD) to temperature change will increase (decrease) in a warmer climate. These opposite sensitivities should be considered when we want to predict the effects of climate change on heating energy consumption in China in the future. PMID:27651063</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27651063','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27651063"><span id="translatedtitle">Changes in the timing, length and heating degree days of the heating <span class="hlt">season</span> in central heating <span class="hlt">zone</span> of China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shen, Xiangjin; Liu, Binhui</p> <p>2016-01-01</p> <p>Climate change affects the demand for energy consumption, especially for heating and cooling buildings. Using daily mean temperature (Tmean) data, this study analyzed the spatiotemporal changes of the starting date for heating (HS), ending date for heating (HE), length (HL) and heating degree day (HDD) of the heating <span class="hlt">season</span> in central heating <span class="hlt">zone</span> of China. Over China's central heating <span class="hlt">zone</span>, regional average HS has become later by 0.97 day per decade and HE has become earlier by 1.49 days per decade during 1960-2011, resulting in a decline of HL (-2.47 days/decade). Regional averaged HDD decreased significantly by 63.22 °C/decade, which implies a decreasing energy demand for heating over the central heating <span class="hlt">zone</span> of China. Spatially, there are generally larger energy-saving rate in the south, due to low average HDD during the heating <span class="hlt">season</span>. Over China's central heating <span class="hlt">zone</span>, Tmean had a greater effect on HL in warm localities and a greater effect on HDD in cold localities. We project that the sensitivity of HL (HDD) to temperature change will increase (decrease) in a warmer climate. These opposite sensitivities should be considered when we want to predict the effects of climate change on heating energy consumption in China in the future. PMID:27651063</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.4537T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.4537T"><span id="translatedtitle">Contrasting sea-<span class="hlt">ice</span> and open-water boundary layers during melt and freeze-up <span class="hlt">seasons</span>: Some result from the Arctic Clouds in Summer Experiment.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tjernström, Michael; Sotiropoulou, Georgia; Sedlar, Joseph; Achtert, Peggy; Brooks, Barbara; Brooks, Ian; Persson, Ola; Prytherch, John; Salsbury, Dominic; Shupe, Matthew; Johnston, Paul; Wolfe, Dan</p> <p>2016-04-01</p> <p>With more open water present in the Arctic summer, an understanding of atmospheric processes over open-water and sea-<span class="hlt">ice</span> surfaces as summer turns into autumn and <span class="hlt">ice</span> starts forming becomes increasingly important. The Arctic Clouds in Summer Experiment (ACSE) was conducted in a mix of open water and sea <span class="hlt">ice</span> in the eastern Arctic along the Siberian shelf during late summer and early autumn 2014, providing detailed observations of the <span class="hlt">seasonal</span> transition, from melt to freeze. Measurements were taken over both <span class="hlt">ice</span>-free and <span class="hlt">ice</span>-covered surfaces, offering an insight to the role of the surface state in shaping the lower troposphere and the boundary-layer conditions as summer turned into autumn. During summer, strong surface inversions persisted over sea <span class="hlt">ice</span>, while well-mixed boundary layers capped by elevated inversions were frequent over open-water. The former were often associated with advection of warm air from adjacent open-water or land surfaces, whereas the latter were due to a positive buoyancy flux from the warm ocean surface. Fog and stratus clouds often persisted over the <span class="hlt">ice</span>, whereas low-level liquid-water clouds developed over open water. These differences largely disappeared in autumn, when mixed-phase clouds capped by elevated inversions dominated in both <span class="hlt">ice</span>-free and <span class="hlt">ice</span>-covered conditions. Low-level-jets occurred ~20-25% of the time in both <span class="hlt">seasons</span>. The observations indicate that these jets were typically initiated at air-mass boundaries or along the <span class="hlt">ice</span> edge in autumn, while in summer they appeared to be inertial oscillations initiated by partial frictional decoupling as warm air was advected in over the sea <span class="hlt">ice</span>. The start of the autumn <span class="hlt">season</span> was related to an abrupt change in atmospheric conditions, rather than to the gradual change in solar radiation. The autumn onset appeared as a rapid cooling of the whole atmosphere and the freeze up followed as the warm surface lost heat to the atmosphere. While the surface type had a pronounced impact on boundary</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996JMS.....7..233L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996JMS.....7..233L"><span id="translatedtitle">Impact of freshwater on a subarctic coastal ecosystem under <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> (southeastern Hudson Bay, Canada) II. Production and export of microalgae</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Legendre, L.; Robineau, B.; Gosselin, M.; Michel, C.; Ingram, R. G.; Fortier, L.; Therriault, J. C.; Demers, S.; Monti, D.</p> <p>1996-02-01</p> <p>In the under-<span class="hlt">ice</span> plume of the Grande rivière de la Baleine (Great Whale River) and offshore waters of southeastern Hudson Bay (Canada), several environmental factors influence the distribution, growth, taxonomic composition and sedimentation of algae found in the sea <span class="hlt">ice</span>, at the <span class="hlt">ice</span>-water interface and in the underlying water column. During the spring and early summer, these factors include: salinity of bottom <span class="hlt">ice</span>, water turbidity, nutrients and vertical stability of the water column. In the present study, relationships between three predictor variables (water salinity, river runoff and <span class="hlt">seasonal</span> air temperature index) and biological variables are used to assess the impact of freshwater on production and export of microalgae. Relationships are derived from existing data, which were collected between 1978 and 1990. Correlations with water salinity are positive for some variables (salinity of bottom <span class="hlt">ice</span>, phosphate, ammonium, Σ:Si, and algae in bottom <span class="hlt">ice</span> and at the interface) and negative for others (coefficient of light attenuation, silicate, ΣN:P, ΣSi:P and water column phytoplankton). Using together salinity and the <span class="hlt">seasonal</span> index leads to improved proportions of explained variance for nitrate, ammonium, ΣN:P and phytoplankton. The amount of sedimenting algae is positively correlated with runoff, and chemical composition (C/N) of the sedimenting material is negatively correlated with salinity. The empirical relationships are applied to the results of a model of river plume dynamics, for three runoff conditions. <span class="hlt">Seasonally</span> averaged total Chl. a concentrations, derived from the model, are higher for maximum river runoff than for mean or minimum conditions. This is because, in the studied environment, areal concentrations of phytoplankton are higher than those of <span class="hlt">ice</span> algae, especially under condition of maximum runoff.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C51A0680T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C51A0680T"><span id="translatedtitle">Tuning The Sea-<span class="hlt">Ice</span> <span class="hlt">Seasonal</span> Cycle Of HadCM3: Can It Reproduce Observed Trends In Sea-<span class="hlt">Ice</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tett, S. F.; Roach, L.; Rae, C.; Cartis, C.; Mineter, M.; Steig, E. J.; Yamazaki, K.; Schurer, A. P.</p> <p>2015-12-01</p> <p>Since high quality satellite observations of sea-<span class="hlt">ice</span> begin in 1979 Artic sea-<span class="hlt">ice</span> extent has declined . Observed losses in Arctic sea-<span class="hlt">ice</span> during September are greater than the majority of models in the CMIP5 archive and the multi-model average. In contrast Antarctic sea-<span class="hlt">ice</span> has increased in contrast to an expected decline. We have carried out a set of perturbations to the HadCM3 model in which we changed the maximum <span class="hlt">ice</span> area (a proxy for <span class="hlt">ice</span> leads), albedo parameterizations, <span class="hlt">ice</span> thermal conductivity and ocean diffusion. Changes in these parameters affected <span class="hlt">ice</span> extent in both the Arctic and Antarctic. We used these simulations to identify four parameters that had most impact on minimum and maximum sea-<span class="hlt">ice</span> extent in both hemispheres. To tune the model we used a Gauss-Newton algorithm to adjust those four parameters to minimize differences between simulated and observed sea-<span class="hlt">ice</span> extents. With this new parameter set we then simulated the period 1940 to 2015 and compared with the default configuration of HadCM3. Compared to the default configuration the perturbed model had greater summer sea-loss in the Arctic and is consistent with observed loss estimates. However, in the Antarctic neither the perturbed or default simulations show an increase in sea-<span class="hlt">ice</span> extent. This is in contrast to the observations which do show an increase in sea-<span class="hlt">ice</span> extent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010DPS....42.3021H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010DPS....42.3021H"><span id="translatedtitle">The Effects of Radiatively Active Water <span class="hlt">Ice</span> Clouds on the Martian Global <span class="hlt">Seasonal</span> Water Cycle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haberle, Robert M.; Montmessin, F.; Kahre, M. A.; Hollingsworth, J. L.; Schaeffer, J.; de Brouchoven de Bergeyck, A.; Wilson, J.</p> <p>2010-10-01</p> <p>Recently, Mars General Circulation Models (MGCM) have begun implementing cloud microphysics packages to better account for their role in the water cycle. Here, we discuss the importance of their radiative effects. For the past several years we have been implementing and testing a state-of-the-art cloud microphysics package into the NASA/Ames MGCM. This package accounts for the nucleation, growth, transport, and settling of a size distribution water <span class="hlt">ice</span> cloud particles in a self-consistent fashion. The model also has flags to activate their solar and infrared radiative effects, which depend on the size and dust content of the <span class="hlt">ice</span> particles. We have performed two simulations of the global water cycle on Mars: one in which the clouds are radiatively inert, and one in which they are radiatively active. We find that the thermal structure of the atmosphere in the radiatively active cloud run compares better with MGS TES and MRO MCS data. However, the water cycle dries out considerably with radiatively active clouds. There are several reasons for this but the main reason appears to be related to a cooling of the North Polar Residual Cap (NPRC) in the model that is brought about by the reflective nature of the clouds that develop in the lower atmosphere immediately above the NPRC. These clouds increase the planetary albedo at these latitudes and reduce the solar flux at the surface, which is not sufficiently compensated for by an increase in downward infrared emission. Our conclusion at this point, based upon comparison with MRO MCS and MARCI data, is that the model is overpredicting the cloud fields in the vicinity of the NPRC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1817868T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1817868T"><span id="translatedtitle">Life under <span class="hlt">ice</span>: Investigating microbial-related biogeochemical cycles in the <span class="hlt">seasonally</span>-covered Great Lake Onego, Russia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thomas, Camille; Ariztegui, Daniel; Victor, Frossard; Emilie, Lyautey; Marie-Elodie, Perga; Life Under Ice Scientific Team</p> <p>2016-04-01</p> <p>The Great European lakes Ladoga and Onego are important resources for Russia in terms of drinking water, energy, fishing and leisure. Because their northern location (North of Saint Petersburgh), these lakes are usually <span class="hlt">ice</span>-covered during winter. Due to logistical reasons, their study has thus been limited to the <span class="hlt">ice</span>-free periods, and very few data are available for the winter <span class="hlt">season</span>. As a matter of fact, comprehension of large lakes behaviour in winter is very limited as compared to the knowledge available from small subpolar lakes or perennially <span class="hlt">ice</span>-covered polar lakes. To tackle this issue, an international consortium of scientists has gathered around the « life under <span class="hlt">ice</span> » project to investigate physical, chemical and biogeochemical changes during winter in Lake Onego. Our team has mainly focused on the characterization and quantification of biological processes, from the water column to the sediment, with a special focus on methane cycling and trophic interactions. A first « on-<span class="hlt">ice</span> » campaign in March 2015 allowed the sampling of a 120 cm sedimentary core and the collection of water samples at multiple depths. The data resulting from this expedition will be correlated to physical and chemical parameters collected simultaneously. A rapid biological activity test was applied immediately after coring in order to test for microbial activity in the sediments. In situ adenosine-5'-triphosphate (ATP) measurements were carried out in the core and taken as an indication of living organisms within the sediments. The presence of ATP is a marker molecule for metabolically active cells, since it is not known to form abiotically. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) were extracted from these samples, and quantified. Quantitative polymerase chain reactions (PCR) were performed on archaeal and bacterial 16S rRNA genes used to reconstruct phylogenies, as well as on their transcripts. Moreover, functional genes involved in the methane and nitrogen cycles</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998JGR...10327689S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998JGR...10327689S"><span id="translatedtitle">A 3-D coupled <span class="hlt">ice</span>-ocean model applied to Hudson Bay, Canada: The <span class="hlt">seasonal</span> cycle and time-dependent climate response to atmospheric forcing and runoff</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saucier, FrançOis J.; Dionne, Jacques</p> <p>1998-11-01</p> <p>A coupled three-dimensional, time-dependent <span class="hlt">ice</span>-ocean model is developed and applied in order to reproduce the basin-scale <span class="hlt">ice</span> and mixed-layer physical properties of Hudson Bay and James Bay, Canada. Models for albedo, evaporation, storms, frazil <span class="hlt">ice</span> production, and radiation are included. Observed monthly means of winds, temperature, precipitation, runoff, and cloudiness are used to force the model and obtain multiyear, steady state, and non-steady state solutions. The <span class="hlt">seasonal</span> cycle in sea <span class="hlt">ice</span> thickness, <span class="hlt">ice</span> concentration, ocean temperature, and salinity is first reproduced. Then we consider a set of five experiments: (1) a strong westerly event from the North Atlantic Oscillation, (2) a year with anomalously high runoff, (3) regulated runoff from hydroelectric development, (4) high autumn winds, and (5) warm conditions. We find that preconditioning of the ocean for winter, controlled by the heat transfer to the atmosphere and freshwater input rates and also related to the mixed-layer depth attained before freezing, has a strong control over the following <span class="hlt">ice</span> <span class="hlt">season</span>. The results show that varying runoff has more of an effect on sea-<span class="hlt">ice</span> production in southeastern Hudson Bay than do temperature changes associated with the North Atlantic Oscillation but that both have a small effect on the <span class="hlt">ice</span> cover when compared to the observed interannual variability. Regulated runoff produces a positive sea-<span class="hlt">ice</span> anomaly during the January-April period which is significant (greater than 10 cm or 10%) in the southeastern part of the bay but less than 1 cm (˜1%) on average. We conclude that ˜90% of the excess winter runoff remains liquid. No significant delay is computed for breakup dates (less than 3 days in southeastern Hudson Bay and less than 1 day overall). Other controls from the atmosphere are required to explain the natural interannual variability of the <span class="hlt">ice</span> cover. Summer and autumn winds, and air temperature (which control heat loss and winter preconditioning), spring</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050160462','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050160462"><span id="translatedtitle">Grounding <span class="hlt">Zone</span> and Tidal Response of the Amery <span class="hlt">Ice</span> Shelf, East Antarctica</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fricker, Helen A.; Sandwell, David; Coleman, Richard; Minster, Bernard</p> <p>2005-01-01</p> <p>This report summarizes the main findings of the research project. Unfortunately, it turned out that there was not a great deal of SAR data over the Amery <span class="hlt">Ice</span> Shelf that we were able to work with on the project; nevertheless, we did make considerable progress on this project, with both the existing SAR data and new field measurements that were collected under this grant. In total we had constructed two SAR interferograms (SSIs), and four SSIs. The latter were combined them to construct two differential SAR interferograms (DSIs;). DSIs are useful because the contribution to the SAR phase from horizontal <span class="hlt">ice</span> motion is eliminated, since the time difference between the first and second pass within both image pairs used to make the DSI is the same for each pair. The SSIs and DSIs have revealed several interesting glaciological features, and have added to our knowledge of the Amery <span class="hlt">Ice</span> Shelf (AIS).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JHyd..464..438C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JHyd..464..438C"><span id="translatedtitle">Normalized difference water indexes have dissimilar performances in detecting <span class="hlt">seasonal</span> and permanent water in the Sahara-Sahel transition <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Campos, João C.; Sillero, Neftalí; Brito, José C.</p> <p>2012-09-01</p> <p>SummaryThe decrease of water resources can enhance poverty and increase insecurity in dry regions, at the same time leading to loss of biological diversity. For these reasons, the information about surface perennial and well-known water sources in the arid and semi-arid regions of Africa has been mapped. However, <span class="hlt">seasonal</span> water can be missed in mapping due to their short and erratic appearance, while the mapping of any aquatic resources represents a foremost priority for protecting social, economic and biological values in the e.g. Sahara-Sahel transition <span class="hlt">zone</span>. Therefore, Remote Sensing becomes crucial to monitor a variety of wetland systems in these regions. This work evaluates the performance of three Normalized Difference Water Indexes [Gao's NDWI (NDWINIR/MIR), McFeeters' NDWI (NDWIG/NIR) and Xu's NDWI (NDWIG/MIR)] in mapping of water systems across Mauritania. Maps with <span class="hlt">seasonal</span> and permanent water were derived, using a multi-temporal series of Landsat 5 TM and Landsat 7 ETM+ images. The performance of indexes was compared based on 551 control points collected during five fieldwork missions to Mauritania between 2007 and 2011. Control points were separated in three classes of water availability (permanent, <span class="hlt">seasonal</span> and non-water points) and then randomly assigned into two data sets: one for selecting the water availability thresholds for index reclassification and another for threshold validation. NDWIG/MIR and NDWINIR/MIR had good performances in detecting permanent and <span class="hlt">seasonal</span> water, respectively, while NDWIG/NIR failed to detect most of the water bodies. The threshold selection generated water maps with <span class="hlt">seasonal</span> and permanent features that might be missing in simple mapping of aquatic systems. The extensive data collection provides novel information about NDWI performances for water delineation in arid and semi-arid regions and for a future management of aquatic environments of the Sahara-Sahel transition <span class="hlt">zone</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.4697R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.4697R"><span id="translatedtitle">Spatial and temporal variations of the length of the <span class="hlt">ice</span>-free <span class="hlt">season</span> in the Arctic in the 1979-2008 period</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodrigues, J.</p> <p>2009-04-01</p> <p>We use the length of the <span class="hlt">ice</span>-free <span class="hlt">season</span> (LIFS) and a quantity designated by inverse sea <span class="hlt">ice</span> index (ISII) to quantify the rapid decline of the Arctic sea <span class="hlt">ice</span> that has been observed in the past decades. The LIFS and ISII in each point for each year between 1979 and 2008 are derived from the daily sea <span class="hlt">ice</span> concentrations C(y,d;i) for cell i on day (y,d) = (year,day) which, in turn, are obtained from satellite passive microwave imagery. We define the LIFS L(y;i) at a certain point i in year y as the number of days between the clearance of the <span class="hlt">ice</span> and the formation (more exactly, the appearance) of the <span class="hlt">ice</span> in that point in that year. If the number of clearances and formations is larger than one the LIFS is defined as the sum of the lengths of all periods between an <span class="hlt">ice</span> clearance and the following <span class="hlt">ice</span> formation. The criteria to identify dates of <span class="hlt">ice</span> clearance and <span class="hlt">ice</span> formation are as follows. We assume that there is clearance on day d if the <span class="hlt">ice</span> concentration is 0.15 or higher on days d - 4,d - 3,d - 2 and d - 1 and below 0.15 on days d,d + 1,d + 2,d + 3 and d + 4. We consider that there is formation on day d if the <span class="hlt">ice</span> concentration is below 0.15 on days d - 4,d - 3,d - 2 and d - 1 and 0.15 or higher on days d,d + 1,d + 2,d + 3 and d + 4. The ISII S(y;i) for point i in year y is given by S(y;i) = 1 - ‘ d=1NC(y,d;i) N , where N is the number of days in the year. This quantity, which varies between zero (when there is a perennial <span class="hlt">ice</span> cover) and one (when there is open water all year round), measures the absence of sea <span class="hlt">ice</span> throughout the year, hence the name inverse sea <span class="hlt">ice</span> index. We argue that these variables are at least as suitable for the purpose of describing the depletion of sea <span class="hlt">ice</span> in the Arctic as those that are more often found in the literature, namely the sea <span class="hlt">ice</span> area and extent at the times of annual minimum. Firstly, the sea <span class="hlt">ice</span> extent and area are global variables while the length of the <span class="hlt">ice</span>-free <span class="hlt">season</span> is a local one, and thus more appropriated to study</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950017531','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950017531"><span id="translatedtitle">Unusual radar echoes from the Greenland <span class="hlt">ice</span> sheet</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rignot, E. J.; Vanzyl, J. J.; Ostro, S. J.; Jezek, K. C.</p> <p>1993-01-01</p> <p>In June 1991, the NASA/Jet Propulsion Laboratory airborne synthetic-aperture radar (AIRSAR) instrument collected the first calibrated data set of multifrequency, polarimetric, radar observations of the Greenland <span class="hlt">ice</span> sheet. At the time of the AIRSAR overflight, ground teams recorded the snow and firn (old snow) stratigraphy, grain size, density, and temperature at <span class="hlt">ice</span> camps in three of the four snow <span class="hlt">zones</span> identified by glaciologists to characterize four different degrees of summer melting of the Greenland <span class="hlt">ice</span> sheet. The four snow <span class="hlt">zones</span> are: (1) the dry-snow <span class="hlt">zone</span>, at high elevation, where melting rarely occurs; (2) the percolation <span class="hlt">zone</span>, where summer melting generates water that percolates down through the cold, porous, dry snow and then refreezes in place to form massive layers and pipes of solid <span class="hlt">ice</span>; (3) the soaked-snow <span class="hlt">zone</span> where melting saturates the snow with liquid water and forms standing lakes; and (4) the ablation <span class="hlt">zone</span>, at the lowest elevations, where melting is vigorous enough to remove the <span class="hlt">seasonal</span> snow cover and ablate the glacier <span class="hlt">ice</span>. There is interest in mapping the spatial extent and temporal variability of these different snow <span class="hlt">zones</span> repeatedly by using remote sensing techniques. The objectives of the 1991 experiment were to study changes in radar scattering properties across the different melting <span class="hlt">zones</span> of the Greenland <span class="hlt">ice</span> sheet, and relate the radar properties of the <span class="hlt">ice</span> sheet to the snow and firn physical properties via relevant scattering mechanisms. Here, we present an analysis of the unusual radar echoes measured from the percolation <span class="hlt">zone</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010095416','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010095416"><span id="translatedtitle"><span class="hlt">Seasonal</span> and Interannual Variations of <span class="hlt">Ice</span> Sheet Surface Elevation at the Summit of Greenland: Observed and Modeled</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zwally, H. Jay; Jun, Li; Koblinsky, Chester J. (Technical Monitor)</p> <p>2001-01-01</p> <p>Observed <span class="hlt">seasonal</span> and interannual variations in the surface elevation over the summit of the Greenland <span class="hlt">ice</span> sheet are modeled using a new temperature-dependent formulation of firn-densification and observed accumulation variations. The observed elevation variations are derived from ERS (European Remote Sensing)-1 and ERS-2 radar altimeter data for the period between April 1992 and April 1999. A multivariate linear/sine function is fitted to an elevation time series constructed from elevation differences measured by radar altimetry at orbital crossovers. The amplitude of the <span class="hlt">seasonal</span> elevation cycle is 0.25 m peak-to-peak, with a maximum in winter and a minimum in summer. Inter-annually, the elevation decreases to a minimum in 1995, followed by an increase to 1999, with an overall average increase of 4.2 cm a(exp -1) for 1992 to 1999. Our densification formulation uses an initial field-density profile, the AWS (automatic weather station) surface temperature record, and a temperature-dependent constitutive relation for the densification that is based on laboratory measurements of crystal growth rates. The rate constant and the activation energy commonly used in the Arrhenius-type constitutive relation for firn densification are also temperature dependent, giving a stronger temperature and <span class="hlt">seasonal</span> amplitudes about 10 times greater than previous densification formulations. Summer temperatures are most important, because of the strong non-linear dependence on temperature. Much of firn densification and consequent surface lowering occurs within about three months of the summer <span class="hlt">season</span>, followed by a surface build-up from snow accumulation until spring. Modeled interannual changes of the surface elevation, using the AWS measurements of surface temperature and accumulation and results of atmospheric modeling of precipitation variations, are in good agreement with the altimeter observations. In the model, the surface elevation decreases about 20 cm over the seven years due</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JASTP..71..356R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JASTP..71..356R"><span id="translatedtitle">The cloud imaging and particle size experiment on the aeronomy of <span class="hlt">ice</span> in the mesosphere mission: Cloud morphology for the northern 2007 <span class="hlt">season</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rusch, D. W.; Thomas, G. E.; McClintock, W.; Merkel, A. W.; Bailey, S. M.; Russell, J. M., III; Randall, C. E.; Jeppesen, C.; Callan, M.</p> <p>2009-03-01</p> <p>The Aeronomy of <span class="hlt">Ice</span> in the Mesosphere (AIM) mission was launched from Vandenberg Air Force Base in California at 4:26:03 EDT on April 25, 2007, becoming the first satellite mission dedicated to the study of noctilucent clouds (NLCs), also known as polar mesospheric clouds (PMC) when viewed from space. We present the first results from one of the three instruments on board the satellite, the Cloud Imaging and Particle Size (CIPS) instrument. CIPS has produced detailed morphology of the Northern 2007 PMC and Southern 2007/2008 <span class="hlt">seasons</span> with 5 km horizontal spatial resolution. CIPS, with its very large angular field of view, images cloud structures at multiple scattering angles within a narrow spectral bandpass centered at 265 nm. Spatial coverage is 100% above about 70° latitude, where camera views overlap from orbit to orbit, and terminates at about 82°. Spatial coverage decreases to about 50% at the lowest latitudes where data are collected (35°). Cloud structures have for the first time been mapped out over nearly the entire summertime polar region. These structures include [`]<span class="hlt">ice</span> rings', spatially small but bright clouds, and large regions ([`]<span class="hlt">ice</span>-free regions') in the heart of the cloud <span class="hlt">season</span> essentially devoid of <span class="hlt">ice</span> particles. The <span class="hlt">ice</span> rings bear a close resemblance to tropospheric convective outflow events, suggesting a point source of mesospheric convection. These rings (often circular arcs) are most likely Type IV NLC ([`]whirls' in the standard World Meteorological Organization (WMO) nomenclature).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Geomo.231..301L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Geomo.231..301L"><span id="translatedtitle">Controls on bedrock bedform development beneath the Uummannaq <span class="hlt">Ice</span> Stream onset <span class="hlt">zone</span>, West Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lane, Timothy P.; Roberts, David H.; Rea, Brice R.; Ó Cofaigh, Colm; Vieli, Andreas</p> <p>2015-02-01</p> <p>This paper investigates the controls on the formation of subglacially eroded bedrock bedforms beneath the topographically confined region upstream of the Uummannaq <span class="hlt">Ice</span> Stream (UIS). During the last glacial cycle, palaeoglaciological conditions are believed to have been similar for all sites in the study, characterised by thick, fast-flowing <span class="hlt">ice</span> moving over a rigid bedrock bed. Classic bedrock bedforms indicative of glacially eroded terrain were mapped, including p-forms, roches moutonnées, and whalebacks. Bedform long axes and plucked face orientations display close correlation (parallel and perpendicular) to palaeo-<span class="hlt">ice</span> flow directions inferred from striae measurements. Across all sites, elongation ratios (length to width) varied by an order of magnitude between 0.8:1 and 8.4:1. Bedform properties (length, height, width, and long axis orientation) from four subsample areas, form morphometrically distinct populations, despite their close proximity and hypothesised similarity in palaeoglaciological conditions. Variations in lithology and geological structures (e.g., joint frequency; joint dip; joint orientation; bedding plane thickness; and bedding plane dip) provide lines of geological weakness, which focus the glacial erosion, in turn controlling bedform geometries. Determining the relationship (s) between bedding plane dip relative to palaeo-<span class="hlt">ice</span> flow and bedform shape, relative length, amplitude, and wavelength has important ramifications for understanding subglacial bed roughness, cavity formation, and likely erosion style (quarrying and/or abrasion) at the <span class="hlt">ice</span>-bed interface. This paper demonstrates a direct link between bedrock bedform geometries and geological structure and emphasises the need to understand bedrock bedform characteristics when reconstructing palaeoglaciological conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000070367&hterms=Continental+Drift&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2528Continental%2BDrift%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000070367&hterms=Continental+Drift&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2528Continental%2BDrift%2529"><span id="translatedtitle"><span class="hlt">Seasonal</span>-to-Interannual Variability in Antarctic Sea-<span class="hlt">Ice</span> Dynamics, and Its Impact on Surface Fluxes and Water Mass Production</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Drinkwater, Mark R.</p> <p>1999-01-01</p> <p>Strong <span class="hlt">seasonal</span> and interannual signals in Antarctic bottom-water outflow remain unexplained yet are highly correlated with anomalies in net sea-<span class="hlt">ice</span> growth in coastal polynyas. The mechanisms responsible for driving salination and replenishment and rejuvenation of the dense shelf "source" waters likely also generate pulses of bottom water outflow. The objective of this research is to investigate time-scales of variability in the dynamics of sea-<span class="hlt">ice</span> in the Southern Ocean in order to determine the primary sites for production of dense shelf waters. We are using a merged satellite/buoy sea-<span class="hlt">ice</span> motion data set for the period 1978-present day to compute the dynamics of opening and closing of coastal polynyas over the continental shelf. The Ocean Circulation and Climate Advanced Model (OCCAM) ocean general circulation model with coupled sea-<span class="hlt">ice</span> dynamics is presently forced using National Center for Environmental Prediction (NCEP) data to simulate fluxes and the salination impact of the ocean shelf regions. This work is relevant in the context of measuring the influence of polar sea-<span class="hlt">ice</span> dynamics upon polar ocean characteristics, and thereby upon global thermohaline ocean circulation. Interannual variability in simulated net freezing rate in the Southern Weddell Sea is shown for the period 1986-1993. There is a pronounced maximum of <span class="hlt">ice</span> production in 1988 and minimum in 1991 in response to anomalies in equatorward meridional wind velocity. This follows a similar approximate 8-year interannual cycle in Sea Surface Temperature (SST) and satellite-derived <span class="hlt">ice</span>-edge anomalies reported elsewhere as the "Antarctic Circumpolar Wave." The amplitude of interannual fluctuations in annual net <span class="hlt">ice</span> production are about 40% of the mean value, implying significant interannual variance in brine rejection and upper ocean heat loss. Southward anomalies in wind stress induce negative anomalies in open water production, which are observed in passive microwave satellite images. Thus, cycles of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/ha/619/plate-3.pdf','USGSPUBS'); return false;" href="http://pubs.usgs.gov/ha/619/plate-3.pdf"><span id="translatedtitle">Columbia Glacier, Alaska recent <span class="hlt">ice</span> loss and its relationship to <span class="hlt">seasonal</span> terminal embayments, thinning and glacial flow</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sikonia, W.G.; Post, Austin</p> <p>1980-01-01</p> <p>In 1974 the U.S. Geological Survey began an intensive investigation of the stability of Columbia Glacier, a calving tidewater galcier terminating in Columbia Bay, near Valdez, Alaska. Aerial photographs taken in 1957 and a sequence of photographs taken at about 2-month intervals since 1976, when analyzed photogrammetrically, provided detailed data on changes in Columbia Glacier 's thickness, flow rate, and terminal position. Annual embayments in the glacier 's terminus form during the summer-autumn <span class="hlt">season</span> in most years; the size of embayments appears to be related to (1) the thickness of the glacier, and (2) the position and nature of subglacial freshwater discharge. Embayments have apparently increased in size in recent years; the largest embayments yet observed formed in 1975, 1976, 1977, and 1978. From April 1, 1977, to April 1, 1978, the total volume of <span class="hlt">ice</span> calved was about 1.0 cubic kilometer. By January 1979 the glacier front had retreated from Heather Island. Glacier flow varies <span class="hlt">seasonally</span> and synchronously in the lower 17 kilometers of the glacier; large accelerations occur near the terminus in response to embayment formation. Daily speed within 5 kilometers of the terminus increased from about 1.9 meters per day between 1963 and 1968 to about 2.7 meters per day between 1977 and 1978. In the lowest 15 kilometers, the glacier surface was lowered about 9 meters between 1957 and 1974, and about 13 meters between 1974 and 1978. Columbia Glacier is being reduced in mass due, in part, to recent losses caused by large embayments forming annually. If such reduction continues it will result in a drastic retreat. (USGS)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3366992','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3366992"><span id="translatedtitle">Habitat Association and <span class="hlt">Seasonality</span> in a Mosaic and Bimodal Hybrid <span class="hlt">Zone</span> between Chorthippus brunneus and C. jacobsi (Orthoptera: Acrididae)</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tatsuta, Haruki; Butlin, Roger K.</p> <p>2012-01-01</p> <p>Understanding why some hybrid <span class="hlt">zones</span> are bimodal and others unimodal can aid in identifying barriers to gene exchange following secondary contact. The hybrid <span class="hlt">zone</span> between the grasshoppers Chorthippus brunneus and C. jacobsi contains a mix of allopatric parental populations and inter-mingled bimodal and unimodal sympatric populations, and provides an ideal system to examine the roles of local selection and gene flow between populations in maintaining bimodality. However, it is first necessary to confirm, over a larger spatial scale, previously identified associations between population composition and <span class="hlt">season</span> and habitat. Here we use cline-fitting of one morphological and one song trait along two valley transects, and intervening mountains, to confirm previously identified habitat associations (mountain versus valley) and <span class="hlt">seasonal</span> changes in population composition. As expected from previous findings of studies on a smaller spatial scale, C. jacobsi dominated mountain habitats and mixed populations dominated valleys, and C. brunneus became more prevalent in August. Controlling for habitat and incorporating into the analysis <span class="hlt">seasonal</span> changes in cline parameters and the standard errors of parental trait values revealed wider clines than previous studies (best estimates of 6.4 to 24.5 km in our study versus 2.8 to 4.7 km in previous studies) and increased percentage of trait variance explained (52.7% and 61.5% for transects 1 and 2 respectively, versus 17.6%). Revealing such strong and consistent patterns within a complex hybrid <span class="hlt">zone</span> will allow more focused examination of the causes of variation in bimodality in mixed populations, in particular the roles of local selection versus habitat heterogeneity and gene flow between differentiated populations. PMID:22675485</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14708745','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14708745"><span id="translatedtitle">Structure and <span class="hlt">seasonal</span> dynamics of hyporheic <span class="hlt">zone</span> microbial communities in free-stone rivers of the western United States.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Feris, K P; Ramsey, P W; Frazar, C; Rillig, M C; Gannon, J E; Holben, W E</p> <p>2003-08-01</p> <p>The hyporheic <span class="hlt">zone</span> of a river is characterized by being nonphotic, exhibiting chemical/redox gradients, and having a heterotrophic food web based on the consumption of organic carbon entrained from surface waters. Hyporheic microbial communities constitute the base of food webs in these environments and are important for maintaining a functioning lotic ecosystem. While microbial communities of rivers dominated by fine-grained sediments are relatively well studied, little is known about the structure and <span class="hlt">seasonal</span> dynamics of microbial communities inhabiting the predominantly gravel and cobble hyporheic <span class="hlt">zones</span> of rivers of the western United States. Here, we present the first molecular analysis of hyporheic microbial communities of three different stream types (based on mean base discharge, substratum type, and drainage area), in Montana. Utilizing 16S rDNA phylogeny, DGGE pattern analysis, and qPCR, we have analyzed the prokaryotic communities living on the 1.7 to 2.36 mm grain-size fraction of hyporheic sediments from three separate riffles in each stream. DGGE analysis showed clear <span class="hlt">seasonal</span> community patterns, indicated similar community composition between different riffles within a stream (95.6-96.6% similarity), and allowed differentiation between communities in different streams. Each river supported a unique complement of species; however, several phylogenetic groups were conserved between all three streams including Pseudomonads and members of the genera Aquabacterium, Rhodoferax, Hyphomicrobium, and Pirellula. Each group showed pronounced <span class="hlt">seasonal</span> trends in abundance, with peaks during the Fall. The Hyphomicrobium group was numerically dominant throughout the year in all three streams. This work provides a framework for investigating the effects of various environmental factors and anthropogenic effects on microbial communities inhabiting the hyporheic <span class="hlt">zone</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C51B0725B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C51B0725B"><span id="translatedtitle">Intra- and Inter-<span class="hlt">Seasonal</span> Supra-glacial Water Variability over the West Greenland <span class="hlt">Ice</span> Sheet as Estimated from Combining High Resolution Satellite Optical Data and a Digital Elevation Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brown, M. G.; Tedesco, M.; Smith, L. C.; Rennermalm, A. K.; Yang, K.</p> <p>2015-12-01</p> <p>The supra-glacial hydrology of the Greenland <span class="hlt">Ice</span> Sheet (GrIS) plays a crucial role on the surface energy and mass balance budgets of the <span class="hlt">ice</span> sheet as a whole. The surface hydrology network variability of small streams in the ablation <span class="hlt">zone</span> of Greenland is poorly understood both spatially and temporally. Using satellites that can spatially resolve the presence and associated properties of small streams, the scientific community is now able to be provided with accurate spatial and temporal analysis of surface hydrology on the <span class="hlt">ice</span> sheet (that could not have been resolved with other sensors such as those on board MODIS or LANDSAT). In this study we report mapped supra-glacial water networks over a region of the West GrIS (approximately 164 km2) derived from high resolution multispectral satellite imagery from the Quickbird and WorldView - 2 satellites in tandem with a 2 meter stereographic SETSM DEM (digital elevation model). The branching complexity of the identified surface streams is computed from the available DEM as well as the intra- and inter <span class="hlt">seasonal</span> changes observed in the hydrological system. The stream networks created during the melt <span class="hlt">season</span> (at several different stages of melting) are compared and discussed as well as the networks mapped between consecutive years for proximate dates. Also, depth and volume estimations for the surface water features identified were extracted via band math algorithms, threshold classifications, and morphological operations. Our results indicate that the higher stream orders have the largest amount of stored surface water per km but the lower stream orders, specifically 1st order with widths of ~ 2 meters, hold more stored surface water overall. We also employ and compare runoff data from the numerical model MAR (Modèle Atmosphérique Régional) to the estimations found using imagery and the DEM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C51B0727H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C51B0727H"><span id="translatedtitle">Albedo and its relationship with <span class="hlt">seasonal</span> surface roughness using repeat UAV survey across the Kangerlussuaq sector of the Greenland <span class="hlt">Ice</span> Sheet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hubbard, A., II; Ryan, J.; Box, J. E.; Snooke, N.</p> <p>2015-12-01</p> <p>Surface albedo is a primary control on absorbed radiation and hence <span class="hlt">ice</span> surface darkening is a powerful amplifier of melt across the margin of the Greenland <span class="hlt">ice</span> sheet. To investigate the relationship between <span class="hlt">ice</span> surface roughness and variations in albedo in space and time at ~dm resolution, a suite of Unmanned Aerial Vehicles (UAVs) were deployed from the margin of Russell Glacier between June and August, 2014. The UAVs were equipped with digital and multispectral cameras, GoPros, fast response broadband pyranometers and temperature and humidity sensors. The primary mission was regular repeat longitudinal transects attaining data from the margin to the equilibrium line 80 km into the <span class="hlt">ice</span> sheet interior and which were complimented by selected watershed and catchment surveys. The pyranometers reliably measure bare <span class="hlt">ice</span> surface albedo between 0.34 and 0.58 that correlate well against concurrent MODIS data (where available). Repeat digital photogrammetric analysis enables investigation of relationship between changing meso- and micro-scale albedo and melt processes modulated by <span class="hlt">ice</span> surface roughness that, in turn, are related to the <span class="hlt">seasonally</span> evolving surface energy balance recorded at three AWS on the flight path.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26154153','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26154153"><span id="translatedtitle">Quantification of the Demands During an <span class="hlt">Ice</span>-Hockey Game Based on Intensity <span class="hlt">Zones</span> Determined From the Incremental Test Outcomes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stanula, Arkadiusz J; Gabryś, Tomasz T; Roczniok, Robert K; Szmatlan-Gabryś, Urszula B; Ozimek, Mariusz J; Mostowik, Aleksandra J</p> <p>2016-01-01</p> <p>The purpose of this study was to determine <span class="hlt">ice</span>-hockey players' playing intensity based on their heart rates (HRs) recorded during a game and on the outcomes of an incremental maximum oxygen uptake test. Sixteen <span class="hlt">ice</span>-hockey players, members of the Polish national team junior (U20), performed an incremental test to assess their maximal oxygen uptake (VO2max) in the 2 week's period preceding 4 games they played at the World Championships. Players' HRs at the first and second ventilatory thresholds obtained during the test were used to determine intensity <span class="hlt">zones</span> (low, moderate, and high) that were subsequently used to classify HR values recorded during each of the games. For individual intensity <span class="hlt">zones</span>, the following HRs expressed as mean values and as percentages of the maximal heart rate (HRmax) were obtained: forwards, 143-151 b · min(-1) (HRmax, 75.2-79.5%), 152-176 b · min(-1) (HRmax, 80.0-92.4%), 177-190 b · min(-1) (HRmax, 92.9-100.0%); defensemen, 127-139 b · min(-1) (HRmax, 69.4-75.8%), 140-163 b · min(-1) (HRmax, 76.4-89.0%), 164-184 b · min(-1) (HRmax, 89.5-100.0%). The amounts of time the forwards and defensemen spent in the 3 intensity <span class="hlt">zones</span> expressed as percentages of the total time of the game were the following: 58.75% vs. 44.29% (low), 21.95% vs. 25.84% (moderate), and 19.30% vs. 29.87% (high). The forwards spent average more time in the low-intensity <span class="hlt">zone</span> than did the defensemen, with the difference being statistically significant in periods 1 and 2 (61.44% vs. 44.21% at p ≤ 0.001 and 59.14% vs. 47.23% at p ≤ 0.01, respectively). The results of the study indicate that a method using aerobic and anaerobic metabolism parameters to determine intensity <span class="hlt">zones</span> can significantly improve the reliability of evaluation of the physiological demands of the game and can be a useful tool for coaches in managing the training process. PMID:26154153</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24296049','USGSPUBS'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24296049"><span id="translatedtitle">Differentiating transpiration from evaporation in <span class="hlt">seasonal</span> agricultural wetlands and the link to advective fluxes in the root <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bachand, P.A.M.; S. Bachand,; Fleck, Jacob A.; Anderson, Frank E.; Windham-Myers, Lisamarie</p> <p>2014-01-01</p> <p>The current state of science and engineering related to analyzing wetlands overlooks the importance of transpiration and risks data misinterpretation. In response, we developed hydrologic and mass budgets for agricultural wetlands using electrical conductivity (EC) as a natural conservative tracer. We developed simple differential equations that quantify evaporation and transpiration rates using flowrates and tracer concentrations atwetland inflows and outflows. We used two ideal reactormodel solutions, a continuous flowstirred tank reactor (CFSTR) and a plug flow reactor (PFR), to bracket real non-ideal systems. From those models, estimated transpiration ranged from 55% (CFSTR) to 74% (PFR) of total evapotranspiration (ET) rates, consistent with published values using standard methods and direct measurements. The PFR model more appropriately represents these nonideal agricultural wetlands in which check ponds are in series. Using a fluxmodel, we also developed an equation delineating the root <span class="hlt">zone</span> depth at which diffusive dominated fluxes transition to advective dominated fluxes. This relationship is similar to the Peclet number that identifies the dominance of advective or diffusive fluxes in surface and groundwater transport. Using diffusion coefficients for inorganic mercury (Hg) and methylmercury (MeHg) we calculated that during high ET periods typical of summer, advective fluxes dominate root <span class="hlt">zone</span> transport except in the top millimeters below the sediment–water interface. The transition depth has diel and <span class="hlt">seasonal</span> trends, tracking those of ET. Neglecting this pathway has profound implications: misallocating loads along different hydrologic pathways; misinterpreting <span class="hlt">seasonal</span> and diel water quality trends; confounding Fick's First Law calculations when determining diffusion fluxes using pore water concentration data; and misinterpreting biogeochemicalmechanisms affecting dissolved constituent cycling in the root <span class="hlt">zone</span>. In addition,our understanding of internal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24296049','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24296049"><span id="translatedtitle">Differentiating transpiration from evaporation in <span class="hlt">seasonal</span> agricultural wetlands and the link to advective fluxes in the root <span class="hlt">zone</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bachand, P A M; Bachand, S; Fleck, J; Anderson, F; Windham-Myers, L</p> <p>2014-06-15</p> <p>The current state of science and engineering related to analyzing wetlands overlooks the importance of transpiration and risks data misinterpretation. In response, we developed hydrologic and mass budgets for agricultural wetlands using electrical conductivity (EC) as a natural conservative tracer. We developed simple differential equations that quantify evaporation and transpiration rates using flow rates and tracer concentrations at wetland inflows and outflows. We used two ideal reactor model solutions, a continuous flow stirred tank reactor (CFSTR) and a plug flow reactor (PFR), to bracket real non-ideal systems. From those models, estimated transpiration ranged from 55% (CFSTR) to 74% (PFR) of total evapotranspiration (ET) rates, consistent with published values using standard methods and direct measurements. The PFR model more appropriately represents these non-ideal agricultural wetlands in which check ponds are in series. Using a flux model, we also developed an equation delineating the root <span class="hlt">zone</span> depth at which diffusive dominated fluxes transition to advective dominated fluxes. This relationship is similar to the Peclet number that identifies the dominance of advective or diffusive fluxes in surface and groundwater transport. Using diffusion coefficients for inorganic mercury (Hg) and methylmercury (MeHg) we calculated that during high ET periods typical of summer, advective fluxes dominate root <span class="hlt">zone</span> transport except in the top millimeters below the sediment-water interface. The transition depth has diel and <span class="hlt">seasonal</span> trends, tracking those of ET. Neglecting this pathway has profound implications: misallocating loads along different hydrologic pathways; misinterpreting <span class="hlt">seasonal</span> and diel water quality trends; confounding Fick's First Law calculations when determining diffusion fluxes using pore water concentration data; and misinterpreting biogeochemical mechanisms affecting dissolved constituent cycling in the root <span class="hlt">zone</span>. In addition, our understanding of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=262189','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=262189"><span id="translatedtitle">Management <span class="hlt">zone</span> delineation techniques to aid in-<span class="hlt">season</span> sensor based nitrogen application</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>The increased efficiency of nitrogen fertilizer (N) use has been a long-term goal in reduction of nitrate contamination in the state of Nebraska. Preliminary research has shown sensor based in-<span class="hlt">season</span> application of nitrogen has the ability to be economic and environmentally viable. Although benefi...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.3145M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.3145M"><span id="translatedtitle">Intra-<span class="hlt">seasonal</span> variability of the Beaufort Gyre and its impact on the fate of Arctic Sea <span class="hlt">ice</span> in the Pacific Sector of the Arctic Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mizobata, Kohei; Kimura, Noriaki</p> <p>2015-04-01</p> <p>Decades of satellite observation have revealed drastic reduction of sea <span class="hlt">ice</span> over the Chukchi Borderland (hereafter CBL) area in the Arctic Ocean. One of the triggers for this reduction is the Pacific Summer Water (hereafter PSW), which enters in the Arctic Basin via the Chukchi Sea. After intruding the Arctic Ocean, the PSW is transported by the clockwise Beaufort Gyre (hereafter, BG) and is delivered to CBL region during wintertime. It is thought that the increase in ocean heat content due to PSW will delay sea <span class="hlt">ice</span> formation. However, there is an inter-annual variability of sea <span class="hlt">ice</span> distribution in the Pacific sector of the Arctic Ocean, indicating the temporal and spatial variability of the PSW. To understand where and when the PSW arrives in the Pacific sector of the Arctic Ocean, we need to elucidate the distribution and strength of the BG during wintertime. Hydrographic observations by the drifting/<span class="hlt">ice</span>-mounted buoy and mooring are quite helpful to obtain in-situ measurements, however, it is hard to elucidate changing spatial and temporal distribution patterns of BG and PSW. In this study, we investigated monthly DOT field derived from the measurements of the Synthetic Aperture Interferometric Radar Altimeter (SIRAL), which is mounted on the Cryosphere Satellite-2 (CryoSat-2). Moreover, we employed 1) the <span class="hlt">ice</span> concentration and <span class="hlt">ice</span> velocity datasets derived from the data observed by the satellite microwave sensors, the Advanced Microwave Scanning Radiometer for EOS (AMSR-E, mounted on the earth observing satellite AQUA) and AMSR2 (mounted on the satellite, Global Change Observation Mission 1st - Water (GCOM-W1)), 2) the NCEP-DOE Reanalysis 2 sea level pressure, to examine sea surface stress field and 3) CryoSat-2 sea <span class="hlt">ice</span> thickness distributed by the AWI. DOTs derived from the Cryosat-2/SIRAL measurements show both inter-annual and intra-<span class="hlt">seasonal</span> variability of the Beaufort Gyre during wintertime. Actually, the Beaufort Gyre responds to changing sea <span class="hlt">ice</span> motion</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014TCry....8.2353T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014TCry....8.2353T"><span id="translatedtitle">Are <span class="hlt">seasonal</span> calving dynamics forced by buttressing from <span class="hlt">ice</span> mélange or undercutting by melting? Outcomes from full-Stokes simulations of Store Glacier, West Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Todd, J.; Christoffersen, P.</p> <p>2014-12-01</p> <p>We use a full-Stokes 2-D model (Elmer/<span class="hlt">Ice</span>) to investigate the flow and calving dynamics of Store Glacier, a fast-flowing outlet glacier in West Greenland. Based on a new, subgrid-scale implementation of the crevasse depth calving criterion, we perform two sets of simulations: one to identify the primary forcing mechanisms and another to constrain future stability. We find that the mixture of icebergs and sea <span class="hlt">ice</span>, known as <span class="hlt">ice</span> mélange or sikussak, is principally responsible for the observed <span class="hlt">seasonal</span> advance of the <span class="hlt">ice</span> front. On the other hand, the effect of submarine melting on the calving rate of Store Glacier appears to be limited. Sensitivity analysis demonstrates that the glacier's calving dynamics are sensitive to <span class="hlt">seasonal</span> perturbation, but are stable on interannual timescales due to the strong topographic control on the flow regime. Our results shed light on the dynamics of calving glaciers and may help explain why neighbouring glaciers do not necessarily respond synchronously to changes in atmospheric and oceanic forcing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24500172','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24500172"><span id="translatedtitle">Longer <span class="hlt">ice</span>-free <span class="hlt">seasons</span> increase the risk of nest depredation by polar bears for colonial breeding birds in the Canadian Arctic.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Iverson, Samuel A; Gilchrist, H Grant; Smith, Paul A; Gaston, Anthony J; Forbes, Mark R</p> <p>2014-03-22</p> <p>Northern polar regions have warmed more than other parts of the globe potentially amplifying the effects of climate change on biological communities. <span class="hlt">Ice</span>-free <span class="hlt">seasons</span> are becoming longer in many areas, which has reduced the time available to polar bears (Ursus maritimus) to hunt for seals and hampered bears' ability to meet their energetic demands. In this study, we examined polar bears' use of an ancillary prey resource, eggs of colonial nesting birds, in relation to diminishing sea <span class="hlt">ice</span> coverage in a low latitude region of the Canadian Arctic. Long-term monitoring reveals that bear incursions onto common eider (Somateria mollissima) and thick-billed murre (Uria lomvia) nesting colonies have increased greater than sevenfold since the 1980s and that there is an inverse correlation between <span class="hlt">ice</span> <span class="hlt">season</span> length and bear presence. In surveys encompassing more than 1000 km of coastline during years of record low <span class="hlt">ice</span> coverage (2010-2012), we encountered bears or bear sign on 34% of eider colonies and estimated greater egg loss as a consequence of depredation by bears than by more customary nest predators, such as foxes and gulls. Our findings demonstrate how changes in abiotic conditions caused by climate change have altered predator-prey dynamics and are leading to cascading ecological impacts in Arctic ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A43G0386O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A43G0386O"><span id="translatedtitle">Climatic <span class="hlt">Zones</span>, Soil Moisture <span class="hlt">Seasonality</span> and Biomass Burning and Their Influence On Ozone Precursor Concentrations Over West Africa as Retrieved from Satellites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Onojeghuo, A. R.; Balzter, H.; Monks, P. S.</p> <p>2015-12-01</p> <p>West Africa is a region with six different climatic <span class="hlt">zones</span> including a rich savannah affected by biomass burning annually, the Niger delta oil producing region with major gas flaring sites and a long coastline. Research on atmospheric pollution using remotely sensed data over West Africa has mostly been conducted at regional scale or for individual countries, with little emphasis on the dynamics of climatic <span class="hlt">zones</span> and the diversity of land cover types. This study analyses annual <span class="hlt">seasonal</span> dynamics of emissions of two ozone precursors stratified by climatic <span class="hlt">zone</span>: nitrogen dioxide (NO2) from OMI and carbon monoxide (CO) from TES. The different sources of these pollutants and their <span class="hlt">seasonality</span> are explicitly considered. Results indicate that the highest annual wet <span class="hlt">season</span> NO2 column concentrations were in the semi-arid <span class="hlt">zone</span> (1.33 x 1015 molecules cm-2) after prolonged periods of low soil moisture while the highest dry <span class="hlt">season</span> were observed in the wet sub-humid <span class="hlt">zone</span> (2.62 x 1015 molecules cm-2) where the savannah fires occur annually. The highest annual CO concentrations (> 3.1 x 1018 molecules cm-2) were from the Niger Delta, located in the humid <span class="hlt">zone</span>. There were indications of atmospheric transport of CO from the southern hemisphere in the west <span class="hlt">season</span>. Climate change induced soil moisture variability was most prominent in the dry sub-humid and semi-arid climatic <span class="hlt">zones</span> (±0.015m3m-3) . The causal effects of soil moisture variability on NO2 emissions and their <span class="hlt">seasonal</span> cycles were tested using the Granger causality test. Causal effects of inter-zonal exchanges/transport of NO2 and CO emissions respectively were inferred using Directed Acyclic Graphs. The results indicate that NO2, CO and their <span class="hlt">seasonal</span> ratios are strongly affected by changes in soil moisture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C11A0748A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C11A0748A"><span id="translatedtitle"><span class="hlt">Seasonal</span> Variation and Controls on Subglacial Riverine CO2 Concentrations From a Small Catchment, West Greenland <span class="hlt">Ice</span> Sheet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andrews, G.; Jacobson, A. D.</p> <p>2015-12-01</p> <p>Previous research has suggested that subglacial discharge from the Greenland <span class="hlt">Ice</span> Sheet (GrIS) may have the potential to be a significant source of CO2 to the atmosphere in a warming world (Ryu and Jacobson, 2011). To trace the flux, sources of, and controls on subglacial CO2, we sampled the Akuliarusiarsuup Kuua River subglacial portal, which receives water from the Isunnguata and Russell Glaciers, west GrIS, six times throughout June - August, 2014. Additionally, we sampled two nearby supraglacial streams. We present preliminary data on pCO2 values, DIC and DOC concentrations, major cation and anion concentrations, δ13CDIC isotopes, as well as ∆14C-DIC and -DOCisotopes. Waters emerging from the subglacial portal are 2 - 2.5x supersaturated in CO2 with respect to atmospheric equilibrium. pCO2 values rise from ~700 to 1000ppm between June and July then return to ~700ppm in August. Although subglacial pCO2 and ∆14CDIC values vary, throughout the summer they exhibit similar trends as contemporaneous supraglacial stream values, suggesting that subglacial CO2 is at least partially derived from supraglacial meltwater which has accessed the <span class="hlt">ice</span> sheet base through moulins and crevasses. δ13CDIC isotopes of supraglacial streams are highly depleted (-24‰), suggesting that CO2 is sourced from microbial respiration of surficial organic carbon. Subglacial portal δ13CDIC isotopes are also relatively depleted (-17‰) but are sufficiently different relative to supraglacial streams so as to require an additional δ13CDIC enriched source. A strong correlation (R2 = 0.89, n= 6) between subglacial Ca+Mg concentrations and alkalinity (≈ HCO3) suggests that the additional source of DIC to these waters is dissolution of carbonate. Finally, the correlation (R2 = 0.55, n = 6) between subglacial pCO2 and ∆14CDOC values suggest that one control on variable CO2 concentrations throughout the melt <span class="hlt">season</span> is the age, and presumably, the lability, of organic carbon available to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRC..121.1806G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRC..121.1806G"><span id="translatedtitle">Replacement of multiyear sea <span class="hlt">ice</span> and changes in the open water <span class="hlt">season</span> duration in the Beaufort Sea since 2004</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Galley, R. J.; Babb, D.; Ogi, M.; Else, B. G. T.; Geilfus, N.-X.; Crabeck, O.; Barber, D. G.; Rysgaard, S.</p> <p>2016-03-01</p> <p>The last decade has witnessed the nine lowest Arctic September sea <span class="hlt">ice</span> extents in the observational record. It also forms the most recent third of the long-term trend in that record, which reached -13.4% decade-1 in 2015. While hemispheric analyses paint a compelling picture of sea <span class="hlt">ice</span> loss across the Arctic, the situation with multiyear <span class="hlt">ice</span> in the Beaufort Sea is particularly dire. This study was undertaken in light of substantial changes that have occurred in the extent of summer multiyear sea <span class="hlt">ice</span> in the Arctic inferred from the passive microwave record. To better elucidate these changes at a sub-regional scale, we use data from the Canadian <span class="hlt">Ice</span> Service archive, the most direct observations of sea <span class="hlt">ice</span> stage-of-development available. We also build upon the only previous sea <span class="hlt">ice</span> climatological analysis for Canada's western Arctic region by sea <span class="hlt">ice</span> stage-of-development that ended in 2004. The annual evolution of sea <span class="hlt">ice</span> by stage of development in Canada's western Arctic changed dramatically between 1983 and 2014. The rate of these changes and their spatial prevalence were most prominent in the last decade. In summer, total sea <span class="hlt">ice</span> loss occurred via reductions in old and first-year sea <span class="hlt">ice</span> over increasingly large areas and over more months per year. Resultant delay of thermodynamic freeze up has increased the annual open water duration in the study region. The winter sea <span class="hlt">ice</span> cover was increasingly composed of first-year sea <span class="hlt">ice</span> at the expense of old <span class="hlt">ice</span>. Breakup timing has not significantly changed in the region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C41B0701R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C41B0701R"><span id="translatedtitle">The Relationship Between Arctic Sea <span class="hlt">Ice</span> Albedo and the Geophysical Parameters of the <span class="hlt">Ice</span> Cover</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riihelä, A.</p> <p>2015-12-01</p> <p>The Arctic sea <span class="hlt">ice</span> cover is thinning and retreating. Remote sensing observations have also shown that the mean albedo of the remaining <span class="hlt">ice</span> cover is decreasing on decadal time scales, albeit with significant annual variability (Riihelä et al., 2013, Pistone et al., 2014). Attribution of the albedo decrease between its different drivers, such as decreasing <span class="hlt">ice</span> concentration and enhanced surface melt of the <span class="hlt">ice</span>, remains an important research question for the forecasting of future conditions of the <span class="hlt">ice</span> cover. A necessary step towards this goal is understanding the relationships between Arctic sea <span class="hlt">ice</span> albedo and the geophysical parameters of the <span class="hlt">ice</span> cover. Particularly the question of the relationship between sea <span class="hlt">ice</span> albedo and <span class="hlt">ice</span> age is both interesting and not widely studied. The recent changes in the Arctic sea <span class="hlt">ice</span> <span class="hlt">zone</span> have led to a substantial decrease of its multi-year sea <span class="hlt">ice</span>, as old <span class="hlt">ice</span> melts and is replaced by first-year <span class="hlt">ice</span> during the next freezing <span class="hlt">season</span>. It is generally known that younger sea <span class="hlt">ice</span> tends to have a lower albedo than older <span class="hlt">ice</span> because of several reasons, such as wetter snow cover and enhanced melt ponding. However, the quantitative correlation between sea <span class="hlt">ice</span> age and sea <span class="hlt">ice</span> albedo has not been extensively studied to date, excepting in-situ measurement based studies which are, by necessity, focused on a limited area of the Arctic Ocean (Perovich and Polashenski, 2012).In this study, I analyze the dependencies of Arctic sea <span class="hlt">ice</span> albedo relative to the geophysical parameters of the <span class="hlt">ice</span> field. I use remote sensing datasets such as the CM SAF CLARA-A1 (Karlsson et al., 2013) and the NASA MeaSUREs (Anderson et al., 2014) as data sources for the analysis. The studied period is 1982-2009. The datasets are spatiotemporally collocated and analysed. The changes in sea <span class="hlt">ice</span> albedo as a function of sea <span class="hlt">ice</span> age are presented for the whole Arctic Ocean and for potentially interesting marginal sea cases. This allows us to see if the the albedo of the older sea</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title36-vol1/pdf/CFR-2010-title36-vol1-sec13-912.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title36-vol1/pdf/CFR-2010-title36-vol1-sec13-912.pdf"><span id="translatedtitle">36 CFR 13.912 - Kantishna area summer <span class="hlt">season</span> firearm safety <span class="hlt">zone</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... firearm safety <span class="hlt">zone</span>. 13.912 Section 13.912 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Denali National Park and... State Omnibus Act Road right-of-way, from the former Mt. McKinley National Park boundary at mile 87.9...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900047002&hterms=Discrimination&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DDiscrimination','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900047002&hterms=Discrimination&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DDiscrimination"><span id="translatedtitle">Airborne discrimination between <span class="hlt">ice</span> and water - Application to the laser measurement of chlorophyll-in-water in a marginal <span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoge, Frank E.; Wright, C. Wayne; Swift, Robert N.; Yungel, James K.</p> <p>1989-01-01</p> <p>The concurrent active-passive measurement capabilities of the NASA Airborne Oceanographic Lidar have been used to (1) discriminate between <span class="hlt">ice</span> and water in a large <span class="hlt">ice</span> field within the Greenland Sea and (2) achieve the detection and measurement of chlorophyll-in-water by laser-induced and water-Raman-normalized pigment fluorescence. Passive upwelled radiances from sea <span class="hlt">ice</span> are significantly stronger than those from the neighboring water, even when the optical receiver field-of-view is only partially filled with <span class="hlt">ice</span>. Thus, weaker passive upwelled radiances, together with concurrently acquired laser-induced spectra, can rather confidently be assigned to the intervening water column. The laser-induced spectrum can then be processed using previously established methods to measure the chlorophyll-in-water concentration. Significant phytoplankton patchiness and elevated chlorophyll concentrations were found within the waters of the melting <span class="hlt">ice</span> compared to <span class="hlt">ice</span>-free regions just outside the <span class="hlt">ice</span> field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.6524D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.6524D"><span id="translatedtitle">The <span class="hlt">seasonal</span> and inter-annual variability of sea-<span class="hlt">ice</span>, ocean circulation and marine ecosystems in the Barents Sea: model results against satellite data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dvornikov, Anton; Sein, Dmitry; Ryabchenko, Vladimir; Gorchakov, Victor; Pugalova, Svetlana</p> <p>2015-04-01</p> <p>This study is aimed at modelling the <span class="hlt">seasonal</span> and inter-annual variability of sea-<span class="hlt">ice</span>, ocean circulation and marine ecosystems in the Barents Sea in the modern period. Adequate description of marine ecosystems in the <span class="hlt">ice</span>-covered seas crucially depends on the accuracy in determining of thicknesses of <span class="hlt">ice</span> and snow on the sea surface which control penetrating photosynthetically active radiation under the <span class="hlt">ice</span>. One of the few models of <span class="hlt">ice</span> able to adequately reproduce the dynamics of sea <span class="hlt">ice</span> is the sea <span class="hlt">ice</span> model HELMI [1], containing 7 different categories of <span class="hlt">ice</span>. This model has been imbedded into the Princeton Ocean Model. With this coupled model 2 runs for the period 1998-2007 were performed under different atmospheric forcing prescribed from NCEP/NCAR and ERA-40 archives. For prescribing conditions at the open boundary, all the necessary information about the horizontal velocity, level, temperature and salinity of the water, <span class="hlt">ice</span> thickness and compactness was taken from the results of the global ocean general circulation model of the Max Planck Institute for Meteorology (Hamburg, Germany) MPIOM [2]. The resulting solution with NCEP forcing with a high accuracy simulates the <span class="hlt">seasonal</span> and inter-annual variability of sea surface temperature (SST) estimated from MODIS data. The maximum difference between the calculated and satellite-derived SSTs (averaged over 4 selected areas of the Barents Sea) during the period 2000-2007 does not exceed 1.5 °C. <span class="hlt">Seasonal</span> and inter-annual variations in the area of <span class="hlt">ice</span> cover are also in good agreement with satellite-derived estimates. Pelagic ecosystem model developed in [3] has been coupled into the above hydrodynamic model and used to calculate the changes in the characteristics of marine ecosystems under NCEP forcing. Preliminarily the ecosystem model has been improved by introducing a parameterization of detritus deposition on the bottom and through the selection of optimal parameters for photosynthesis and zooplankton grazing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1811030K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1811030K&link_type=ABSTRACT"><span id="translatedtitle">The moisture updrafts on the cold pool captured by the continuously radiosonde observation passing through the marginal <span class="hlt">ice</span> <span class="hlt">zone</span> in Laptev Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Komatsu, Kensuke; Tachibana, Yoshihiro; Alexeev, Vladimir</p> <p>2016-04-01</p> <p>In summer 2013, we conducted 6 hourly radiosonde observation between off-<span class="hlt">ice</span> and on-<span class="hlt">ice</span> by Russian icebreaker "Akademik Fedorov" passing through the marginal <span class="hlt">ice-zone</span> in Laptev Sea during NABOS project (Nansen and Amundsen Basins Obsevational System). During observation period, the warmer and humid air mass was advected by southeasterly wind from Siberia to Laptev sea because the low-pressure system was passing The temperature profiles bellow 600 m was maintaining the cold pool associated with a sea <span class="hlt">ice</span> and the inversion layer formed above it. The humidity profiles were, however, not trapped until the height of inversion layer, they reached at higher levels (< 5000 m). These observational evidences implied that the humid air from Siberia was lifted on the cold pool maintained by sea <span class="hlt">ice</span> and this process could transport the moisture to upper level in the arctic region. To verify these processes and examine the impact of the existence of sea <span class="hlt">ice</span>, we conducted the numerical experiment by WRF. Three boundary conditions were adopted to simulation; present sea <span class="hlt">ice</span>, removed all sea <span class="hlt">ice</span>, and increased sea <span class="hlt">ice</span> area. As primary results, the trajectories of air parcel from Siberia was rising to upper level with released the latent heat due to the condensation of humid air. The case of present sea <span class="hlt">ice</span> transported much moisture vertically in the arctic region than other two cases. More detail results will be reported on the day. The process of the vertical moisture lifting due to the cold pool could contribute to the heat transport from the mid-latitude surface to the upper level in the arctic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.U61B..05P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.U61B..05P"><span id="translatedtitle">Looking Through the <span class="hlt">Ice</span>: Searching for Past and Present Habitable <span class="hlt">Zones</span> in the Martian North Polar Region Using MOLA DEMs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Payne, M. C.; Farmer, J. D.</p> <p>2002-12-01</p> <p>Hydrothermal systems have been acknowledged as important gateways to accessing a potential subsurface biology (extant or extinct) on Mars. Groundwater circulation, sustained for up to one billion years by large plutonic bodies (as modeled by previous authors), might well be capable of tapping into a deep subsurface biosphere and subsequently carrying members of microbial communities to the surface. Hence, future robotic missions with near surface drilling capabilities may be able to unearth cryopreserved biosignatures, or perhaps extant organisms, in the midst of the hydrothermal system itself. Digital Elevation Models (DEMs) constructed from Mars Orbiter Laser Altimeter (MOLA) data have proved to be a valuable tool in the search for potential habitable <span class="hlt">zones</span> for extant and extinct life, and the detection of possible hydrothermal systems on Mars. When formatted for use in a Geographical Information Systems (GIS) software package such as ESRI's ArcView, MOLA data can be used to compose DEMs. Those DEMs can, in turn, be used to create contour maps, to allow profiling through features of interest, and to generate hillshaded views, which provide an image-like perspective of a selected area. Furthermore, DEMs eliminate many problems associated with photographic images such as over-/underexposure, poor focus, and albedo values too high or low for optimal observations. During this study, DEMs were used in the analysis of several regions north of 70° N latitude, in the Martian north polar cap and polar cap margin. The regions were selected during a Viking image survey that concentrated on the location of surface expressions of potential magma-<span class="hlt">ice</span> interactions, and hence past or present hydrothermal activity. Specific features sought included individual volcanoes and volcanic fields, as well as pseudocrater fields, subglacial volcanic constructs (such as tuyas and tindar ridges), fluvial channels and outwash plains (indicative of j”kulhlaup flooding events), possible</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050179461','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050179461"><span id="translatedtitle">Sea <span class="hlt">Ice</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parkinson, Claire L.; Cavalieri, Donald J.</p> <p>2005-01-01</p> <p>Sea <span class="hlt">ice</span> covers vast areas of the polar oceans, with <span class="hlt">ice</span> extent in the Northern Hemisphere ranging from approximately 7 x 10(exp 6) sq km in September to approximately 15 x 10(exp 6) sq km in March and <span class="hlt">ice</span> extent in the Southern Hemisphere ranging from approximately 3 x 10(exp 6) sq km in February to approximately 18 x 10(exp 6) sq km in September. These <span class="hlt">ice</span> covers have major impacts on the atmosphere, oceans, and ecosystems of the polar regions, and so as changes occur in them there are potential widespread consequences. Satellite data reveal considerable interannual variability in both polar sea <span class="hlt">ice</span> covers, and many studies suggest possible connections between the <span class="hlt">ice</span> and various oscillations within the climate system, such as the Arctic Oscillation, North Atlantic Oscillation, and Antarctic Oscillation, or Southern Annular Mode. Nonetheless, statistically significant long-term trends are also apparent, including overall trends of decreased <span class="hlt">ice</span> coverage in the Arctic and increased <span class="hlt">ice</span> coverage in the Antarctic from late 1978 through the end of 2003, with the Antarctic <span class="hlt">ice</span> increases following marked decreases in the Antarctic <span class="hlt">ice</span> during the 1970s. For a detailed picture of the <span class="hlt">seasonally</span> varying <span class="hlt">ice</span> cover at the start of the 21st century, this chapter includes <span class="hlt">ice</span> concentration maps for each month of 2001 for both the Arctic and the Antarctic, as well as an overview of what the satellite record has revealed about the two polar <span class="hlt">ice</span> covers from the 1970s through 2003.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C21E..02L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C21E..02L"><span id="translatedtitle">Physical Mechanisms Controlling Interannual and <span class="hlt">Seasonal</span> Variations in Melt Pond Evolution on First-Year Sea <span class="hlt">Ice</span> in the Canadian Arctic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Landy, J.; Ehn, J. K.; Shields, M.; Barber, D. G.</p> <p>2014-12-01</p> <p>At the transition between spring and summer, melt ponds form and evolve at the surface of Arctic sea <span class="hlt">ice</span>, significantly modifying energy exchanges between the <span class="hlt">ice</span>, atmosphere and ocean. Past observations have demonstrated that the fractional coverage of melt ponds on Arctic sea <span class="hlt">ice</span> can vary widely over the course of a melt <span class="hlt">season</span>, between years in the same location, and between regions. Here we present two years of melt pond observations from landfast, first-year sea <span class="hlt">ice</span> in the Canadian Arctic, and analyze which physical mechanisms were responsible for considerable interannual variations in melt pond coverage. In general, the key factors affecting pond coverage were: (1) premelt surface topography, (2) the number of drainage features in the <span class="hlt">ice</span> and locations of drainage channels, (3) the evolution of <span class="hlt">ice</span> temperature, and (4) the surface energy balance. Terrestrial LiDAR measurements showed that the premelt topography was rougher in 2011 than in 2012, which led to interannual variations in maximum pond coverage and hydraulic head of 20 pp and 7 cm, respectively. A change in the meltwater balance (production minus drainage) caused the ponds to spread or recede over an area that was almost 90% larger in 2012 than in 2011. The LiDAR measurements also demonstrated that premelt topography was modified due to preferential melting under meltwater drainage channels. Some melt ponds in areas of low-lying premelt topography were unexpectedly drained as the ponds became elevated above deepening channels. Although the sea <span class="hlt">ice</span> cover was 0.35 m thinner in 2012 than in 2011, <span class="hlt">ice</span> interior temperatures remained colder later into June, delaying a transition in <span class="hlt">ice</span> permeability that would allow vertical meltwater drainage from ponds. This permeability transition was observed in 2011 and contributed to a significant drop in pond coverage. For more information see: Landy, J., J. Ehn, M. Shields, and D. Barber (2014), Surface and melt pond evolution on landfast first-year sea <span class="hlt">ice</span> in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRC..119.3645S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRC..119.3645S"><span id="translatedtitle">Annual primary production in Antarctic sea <span class="hlt">ice</span> during 2005-2006 from a sea <span class="hlt">ice</span> state estimate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saenz, Benjamin T.; Arrigo, Kevin R.</p> <p>2014-06-01</p> <p>Using the data-bounded Sea <span class="hlt">Ice</span> Ecosystem State (SIESTA) model, we estimate total Antarctic sea <span class="hlt">ice</span> algal primary production to be 23.7 Tg C a-1 for the period July 2005-June 2006, of which 80% occurred in the bottom 0.2 m of <span class="hlt">ice</span>. Simulated sea <span class="hlt">ice</span> primary production would constitute 12% of total annual primary production in the Antarctic sea <span class="hlt">ice</span> <span class="hlt">zone</span>, and ˜1% of annual Southern Ocean primary production. Model sea <span class="hlt">ice</span> algal growth was net nutrient limited, rather than light limited, for the vast majority of the sunlit <span class="hlt">season</span>. The <span class="hlt">seasonal</span> distribution of integrated <span class="hlt">ice</span> algal biomass matches available observations. The vertical algal distribution was weighted toward the <span class="hlt">ice</span> bottom compared to observations, indicating that interior <span class="hlt">ice</span> algal communities may be under-predicted in the model, and that nutrient delivery via gravity-induced convection is not sufficient to sustain summertime algal biomass. Bottom <span class="hlt">ice</span> algae were most productive in <span class="hlt">ice</span> of 0.36 m thickness, whereas interior algal communities were most productive in <span class="hlt">ice</span> of 1.10 m thickness. Sensitivity analyses that tested different atmospheric forcing inputs, sea <span class="hlt">ice</span> parameterizations, and nutrient availability caused mean and regional shifts in sea <span class="hlt">ice</span> state and <span class="hlt">ice</span> algal production even when sea extent and motion was specified. The spatial heterogeneity of both <span class="hlt">ice</span> state and algal production highlight the sensitivity of the sea <span class="hlt">ice</span> ecosystem to physical perturbation, and demonstrate the importance of quality input data and appropriate parameterizations to models of sea <span class="hlt">ice</span> and associated biology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.G13B0949L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.G13B0949L"><span id="translatedtitle"><span class="hlt">Seasonal</span> Variation of the Cryopsheric Systems on the Alaskan Arctic Coast From InSAR Analysis Using <span class="hlt">Ice</span>-phase ERS-2 Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, L.; Zebker, H. A.</p> <p>2012-12-01</p> <p>We apply Interferometric Synthetic Aperture Radar (InSAR) analysis to monitor <span class="hlt">seasonal</span> deformation over the Arctic-coastal Alaska cryosphere region continuously from winter to summer. From March through July 2011, the last few months of the European Space Agency's ERS-2 mission, the satellite was maneuvered into a '<span class="hlt">Ice</span> Phase' campaign with a three day repeat orbit. This much shorter revisit period, compared to the usual 35 day interval, greatly reduces the temporal decorrelation that hinders InSAR applications. On the other hand, earlier failure of the on-board gyroscope limits InSAR usefulness due to significant spatial and temporal variations of radar Doppler frequencies. Here we compensate for this system problem by modeling the Doppler centroid as a quadratic function of the radar range to estimate and track any Doppler ambiguity, so that we are able to produce a set of interferograms over the <span class="hlt">ice</span> phase period. The winter interferograms alone clearly show fast processes such as motion of the Beaufort sea <span class="hlt">ice</span> and lake <span class="hlt">ice</span> covering the thaw lakes. The spring interferograms reveal detailed, cm-level changes in the area and elevation over the Kuparuk and Sagavanirktok River floodplains and the delta plains near Prudhoe Bay. These changes are associated with snow melting and sea <span class="hlt">ice</span> break-up. Comparisons between the winter and the summer interferograms reveal dramatic <span class="hlt">seasonal</span> variations on the tundra landscape. Our study promises to enable a wide range of new InSAR applications in cryospheric sciences using the C-band SAR data acquired by the Sentinel-1 mission due to launch in 2013. The Sentinel-1 twin satellites are expected to provide coverage over Europe and North America every 1-3 days. Two 3-day interferograms showing distinct InSAR phases and amplitudes on the Arctic coast of Alaska.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1818346P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1818346P"><span id="translatedtitle">Numerical simulations of the impact of <span class="hlt">seasonal</span> heat storage on source <span class="hlt">zone</span> emission in a TCE contaminated aquifer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Popp, Steffi; Beyer, Christof; Dahmke, Andreas; Bauer, Sebastian</p> <p>2016-04-01</p> <p>In urban regions, with high population densities and heat demand, <span class="hlt">seasonal</span> high temperature heat storage in the shallow subsurface represents an attractive and efficient option for a sustainable heat supply. In fact, the major fraction of energy consumed in German households is used for room heating and hot water production. Especially in urbanized areas, however, the installation of high temperature heat storage systems is currently restricted due to concerns on negative influences on groundwater quality caused e.g. by possible interactions between heat storages and subsurface contaminants, which are a common problem in the urban subsurface. Detailed studies on the overall impact of the operation of high temperature heat storages on groundwater quality are scarce. Therefore, this work investigates possible interactions between groundwater temperature changes induced by heat storage via borehole heat exchangers and subsurface contaminations by numerical scenario analysis. For the simulation of non-isothermal groundwater flow, and reactive transport processes the OpenGeoSys code is used. A 2D horizontal cross section of a shallow groundwater aquifer is assumed in the simulated scenario, consisting of a sandy sediment typical for Northern Germany. Within the aquifer a residual trichloroethene (TCE) contaminant source <span class="hlt">zone</span> is present. Temperature changes are induced by a <span class="hlt">seasonal</span> heat storage placed within the aquifer with scenarios of maximum temperatures of 20°C, 40°C and 60°C, respectively, during heat injection and minimum temperatures of 2°C during heat extraction. In the scenario analysis also the location of the heat storage relative to the TCE source <span class="hlt">zone</span> and plume was modified. Simulations were performed in a homogeneous aquifer as well as in a set of heterogeneous aquifers with hydraulic conductivity as spatially correlated random fields. In both cases, results show that the temperature increase in the heat plume and the consequential reduction of water</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011DSRII..58.1948F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011DSRII..58.1948F"><span id="translatedtitle">Macrofauna under sea <span class="hlt">ice</span> and in the open surface layer of the Lazarev Sea, Southern Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Flores, Hauke; van Franeker, Jan-Andries; Cisewski, Boris; Leach, Harry; Van de Putte, Anton P.; Meesters, Erik (H. W. G.); Bathmann, Ulrich; Wolff, Wim J.</p> <p>2011-10-01</p> <p>A new fishing gear was used to sample the macrozooplankton and micronekton community in the surface layer (0-2 m) under <span class="hlt">ice</span> and in open water, the Surface and Under <span class="hlt">Ice</span> Trawl (SUIT). In total, 57 quantitative hauls were conducted in the Lazarev Sea (Southern Ocean) during 3 different <span class="hlt">seasons</span> (autumn 2004, winter 2006, summer 2007/2008). At least 46 species from eight phyla were caught in all 3 <span class="hlt">seasons</span> combined. Biomass density was dominated by Antarctic krill Euphausia superba. The average biomass density was highest under the winter sea <span class="hlt">ice</span> and lowest under the young <span class="hlt">ice</span> in autumn. In summer, macrozooplankton biomass was dominated by ctenophores in open water and by Antarctic krill under <span class="hlt">ice</span>. The community composition varied significantly among <span class="hlt">seasons</span>, and according to the presence of sea <span class="hlt">ice</span>. The response of the community composition to the presence of sea <span class="hlt">ice</span> was influenced by species that were significantly more abundant in open water than under <span class="hlt">ice</span> ( Cyllopus lucasii, Hyperiella dilatata), only <span class="hlt">seasonally</span> abundant under <span class="hlt">ice</span> ( Clione antarctica), or significantly associated with sea <span class="hlt">ice</span> ( Eusirus laticarpus). A number of abundant species showed distinct diel patterns in the surface occurrence both under <span class="hlt">ice</span> and in open water, indicating that the surface layer serves as a foraging ground predominantly at night. Our results emphasize the potential of a number of non-euphausiid macrozooplankton and micronekton species to act as energy transmitters between the production of sea <span class="hlt">ice</span> biota and the pelagic food web. By providing a regional-scale quantitative record of macrofauna under Antarctic sea <span class="hlt">ice</span> covering 3 <span class="hlt">seasons</span>, this study adds new and direct evidence that the <span class="hlt">ice</span>-water interface layer is a major functional node in the ecosystem of the Antarctic <span class="hlt">seasonal</span> sea <span class="hlt">ice</span> <span class="hlt">zone</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1713469S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1713469S"><span id="translatedtitle">Analysis of <span class="hlt">seasonal</span> and diurnal dynamics of green house gases emission urban ecosystems of forest-steppe <span class="hlt">zone</span> of Russia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sarzhanov, Dmitrii; Vasenev, Viacheslav; Sotnikova, Iuliia; Vasenev, Ivan; Valentini, Riccardo</p> <p>2015-04-01</p> <p>Global climate change, mainly determined by increased anthropic emissions of green house gases (GHG) (CO2, CH4, N2O), is among the key contemporary environmental problems. Land use is a principal parameter, distinguishing GHG fluxed in terrestrial ecosystems. Urbanization increase is an important feature of recent land-use change. Formation of urban soils, which are significantly different form natural ones, is one of urbanization results. Urban soils provide a key element of urban ecosystems. Urban ecosystems located in forest-steppe <span class="hlt">zone</span> in Central-Chernozemic region of Russia are of especial interest, since zonal soil in the region are represented by chernozems and dark grey soils, having the largest carbon stocks and the highest rate of soil respiration. Spatial and temporal variability of urban soil's respiration was carried out over vegetation <span class="hlt">seasons</span> of 2013-2014 in different functional <span class="hlt">zone</span> of the Kursk city: residential, recreational and industrial. GHG fluxes were measured once in 10 days before 12 am by chamber approach. CO2 flux was measured in situ using Li-820 close-path analyzer. Diurnal dynamic of CO2 efflux from soil was measured twice a year: in cold and warm <span class="hlt">season</span>. Soil air samples were collected by syringe into glass vials and further analyzed on GC to estimate CH4 and N2O fluxes. Soil temperature and moisture was measured in parallel to soil respiration. CO2emission estimated for urban soils in 2013-2014 was 20-25% higher than in reference zonal soils. Obtained <span class="hlt">seasonal</span> dynamics showed the highest СО2 emissions in August of 2013 (39-83 g СО2/m2 day) with further decrease by the end of October for major part of the plots. Significant diurnal dynamics was found for the case of the industrial <span class="hlt">zone</span>. Maximal CO2 emission was obtained between maximal 40 g СО2/m2 day at 5 AM and 1 PM and minimal 28 g СО2/m2 day at 23 PM in June. Soil CO2 efflux was positively correlated with soil temperature (r = 0.65) and negatively correlated with soil</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7949318','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7949318"><span id="translatedtitle">Population dynamics of anthropophilic mosquitoes during the northeast monsoon <span class="hlt">season</span> in the malaria epidemic <span class="hlt">zone</span> of Sri Lanka.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ramasamy, M S; Kulasekera, R; Srikrishnaraj, K A; Ramasamy, R</p> <p>1994-07-01</p> <p>Mosquito-borne diseases are a major health problem in Sri Lanka. Human biting mosquitoes were collected during the night (18.00-06.00 hours) at Nikawehera village, in the malaria endemic intermediate rainfall <span class="hlt">zone</span> of the country. Collections were made at monthly intervals in the period October 1991 to April 1992, which included the main rainy <span class="hlt">season</span> due to the northeast monsoon (October-January). Thirteen Anopheles, eleven Culex, three Aedes, three Mansonia and one Armigeres species were identified, including known vectors of malaria, Bancroftian filariasis, Japanese encephalitis and dengue fever. Mosquito human-biting rates were highest in December. The main malaria vector Anopheles culicifacies showed peak biting between 18.00 and 23.00 hours whereas the predominant culicines Culex fuscocephala and Cx quinquefasciatus preferred to bite after midnight. In 1991-92 the prevalence of some species of anophelines at Nikawehera differed markedly from that observed in 1990-91 and the possible reasons are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70028080','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70028080"><span id="translatedtitle">Satellite-derived, melt-<span class="hlt">season</span> surface temperature of the Greenland <span class="hlt">Ice</span> Sheet (2000-2005) and its relationship to mass balance</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hall, D.K.; Williams, R.S.; Casey, K.A.; DiGirolamo, N.E.; Wan, Z.</p> <p>2006-01-01</p> <p>Mean, clear-sky surface temperature of the Greenland <span class="hlt">Ice</span> Sheet was measured for each melt <span class="hlt">season</span> from 2000 to 2005 using Moderate-Resolution Imaging Spectroradiometer (MODIS)-derived land-surface temperature (LST) data-product maps. During the period of most-active melt, the mean, clear-sky surface temperature of the <span class="hlt">ice</span> sheet was highest in 2002 (-8.29 ?? 5.29??C) and 2005 (-8.29 ?? 5.43??C), compared to a 6-year mean of -9.04 ?? 5.59??C, in agreement with recent work by other investigators showing unusually extensive melt in 2002 and 2005. Surface-temperature variability shows a correspondence with the dry-snow facies of the <span class="hlt">ice</span> sheet; a reduction in area of the dry-snow facies would indicate a more-negative mass balance. Surface-temperature variability generally increased during the study period and is most pronounced in the 2005 melt <span class="hlt">season</span>; this is consistent with surface instability caused by air-temperature fluctuations. Copyright 2006 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=168608','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=168608"><span id="translatedtitle">Characterization of the sediment bacterial community in groundwater discharge <span class="hlt">zones</span> of an alkaline fen: a <span class="hlt">seasonal</span> study.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gsell, T C; Holben, W E; Ventullo, R M</p> <p>1997-01-01</p> <p>The cell density, activity, and community structure of the bacterial community in wetland sediments were monitored over a 13-month period. The study was performed at Cedar Bog, an alkaline fen. The objective was to characterize the relationship between the sediment bacterial community in groundwater upwelling <span class="hlt">zones</span> and the physical and chemical factors which might influence the community structure and activity. DNA, protein, and lipid synthesis were measured at three different upwelling <span class="hlt">zones</span> by using [3H]thymidine, [14C]leucine, and [14C]glucose incorporation, respectively. The physiological status (apparent stress) of the consortium was assessed by comparing [14C]glucose incorporation into membrane and that into storage lipids. Bacterial cell density was determined by acridine orange direct counts, and gross bacterial community structure was determined by bisbenzimidazole-cesium chloride gradient analysis of total bacterial community DNA. Both <span class="hlt">seasonal</span> and site-related covariation were observed in all estimates of bacterial biomass and activity. Growth rate estimates and cell density peaked in late July at 2.5 x 10(8) cells/g/day and 2.7 x 10(9) cells/g, respectively, and decreased in December to 2.0 x 10(7) cells/g/day and 1.5 x 10(9) cells/g, respectively. Across sites, membrane-to-storage-lipid ratios were generally highest in late spring and peaked in September for one site. Overall, the data indicate dynamic <span class="hlt">seasonal</span> differences in sediment bacterial community activity and physiology, possibly in response to changing physical and chemical environmental factors which included the C/N/P ratios of the perfusing groundwater. By contrast, total cell numbers were rather constant, and community structure analysis indicated that the overall community structure was similar throughout the study. PMID:9251197</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014P%26SS..103..191G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014P%26SS..103..191G"><span id="translatedtitle">Planetary landing-<span class="hlt">zone</span> reconnaissance using <span class="hlt">ice</span>-penetrating radar data: Concept validation in Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grima, Cyril; Schroeder, Dustin M.; Blankenship, Donald D.; Young, Duncan A.</p> <p>2014-11-01</p> <p>The potential for a nadir-looking radar sounder to retrieve significant surface roughness/permittivity information valuable for planetary landing site selection is demonstrated using data from an airborne survey of the Thwaites Glacier Catchment, West Antarctica using the High Capability Airborne Radar Sounder (HiCARS). The statistical method introduced by Grima et al. (2012. Icarus 220, 84-99. http://dx.doi.org/10.1007/s11214-012-9916-y) for surface characterization is applied systematically along the survey flights. The coherent and incoherent components of the surface signal, along with an internally generated confidence factor, are extracted and mapped in order to show how a radar sounder can be used as both a reflectometer and a scatterometer to identify regions of low surface roughness compatible with a planetary lander. These signal components are used with a backscattering model to produce a landing risk assessment map by considering the following surface properties: Root mean square (RMS) heights, RMS slopes, roughness homogeneity/stationarity over the landing ellipse, and soil porosity. Comparing these radar-derived surface properties with simultaneously acquired nadir-looking imagery and laser-altimetry validates this method. The ability to assess all of these parameters with an <span class="hlt">ice</span> penetrating radar expands the demonstrated capability of a principle instrument in icy planet satellite science to include statistical reconnaissance of the surface roughness to identify suitable sites for a follow-on lander mission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..43.3150H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.3150H"><span id="translatedtitle"><span class="hlt">Ice</span> mass loss in Greenland, the Gulf of Alaska, and the Canadian Archipelago: <span class="hlt">Seasonal</span> cycles and decadal trends</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harig, Christopher; Simons, Frederik J.</p> <p>2016-04-01</p> <p>Over the past several decades mountain glaciers and <span class="hlt">ice</span> caps have been significant contributors to sea level rise. Here we estimate the <span class="hlt">ice</span> mass changes in the Canadian Archipelago, the Gulf of Alaska, and Greenland since 2003 by analyzing time-varying gravimetry data from the Gravity Recovery and Climate Experiment. Prior to 2013, interannual <span class="hlt">ice</span> mass variability in the Gulf of Alaska and in regions around Greenland remains within the average estimated over the whole data span. Beginning in summer 2013, <span class="hlt">ice</span> mass in regions around Greenland departs positively from its long-term trend. Over Greenland this anomaly reached almost 500 Gt through the end of 2014. Overall, long-term <span class="hlt">ice</span> mass loss from Greenland and the Canadian Archipelago continues to accelerate, while losses around the Gulf of Alaska region continue but remain steady with no significant acceleration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7150N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7150N"><span id="translatedtitle">Vertical distribution of tropospheric BrO in the marginal sea <span class="hlt">ice</span> <span class="hlt">zone</span> of the Northern Weddell Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nasse, Jan-Marcus; Zielcke, Johannes; Lampel, Johannes; Buxmann, Joelle; Frieß, Udo; Platt, Ulrich</p> <p>2015-04-01</p> <p>The free radical bromine monoxide (BrO) strongly influences the chemistry of the troposphere in Polar regions. During springtime with the return of sunlight after Polar night BrO is released in an autocatalytic reaction mechanism from saline surfaces (bromine explosion). Then BrO affects the oxidative properties of the lower atmosphere and can induce complete depletion of ozone within a matter of days or even hours. In addition, elemental mercury can be oxidized by BrO which makes this toxic compound soluble leading to a deposition into the biosphere. Despite numerous observations of elevated BrO levels in the Polar troposphere, bromine radical sources, as well as the details of the mechanisms leading to bromine explosions and the interactions between atmospheric dynamics and chemistry are not yet completely understood. To improve the understanding of these processes, an accurate determination of the spatio-temporal distribution of BrO is crucial. Here we present measurements of BrO performed during two cruises of the German research <span class="hlt">ice</span> breaker Polarstern in the marginal sea <span class="hlt">ice</span> <span class="hlt">zone</span> of the Antarctic Weddell Sea between June and October 2013 when four major periods with elevated BrO concentrations and simultaneous ozone depletion occurred. The events were observed by (1) a ship-based Multi AXis Differential Absorption Spectroscopy (MAX-DOAS) instrument on Polarstern and (2) a compact MAX-DOAS instrument operated on a helicopter. Several flights were performed in the boundary layer as well as in the free troposphere up to altitudes of 2300 m on days with elevated BrO levels. Vertical profiles of aerosol extinction and BrO concentrations were retrieved for both instruments using our HEIPRO (HEIdelberg Profile) retrieval algorithm based on optimal estimation. Elevated BrO levels in the time series from ship-borne measurements show a strong correlation to southerly wind directions indicating transport from sea <span class="hlt">ice</span> areas. Maximum retrieved BrO mixing ratios at ground</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010097719','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010097719"><span id="translatedtitle">Evaluation of NCAR <span class="hlt">Icing</span>/SLD Forecasts, Tools and Techniques Used During The 1998 NASA SLD Flight <span class="hlt">Season</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bernstein, Ben C.</p> <p>2001-01-01</p> <p>Supercooled Large Droplet (SLD) <span class="hlt">icing</span> conditions were implicated in at least one recent aircraft crash, and have been associated with other aircraft incidents. Inflight encounters with SLD can result in <span class="hlt">ice</span> accreting on unprotected areas of the wing where it can not be removed. Because this <span class="hlt">ice</span> can adversely affect flight characteristics of some aircraft, there has been concern about flight safety in these conditions. The FAA held a conference on in-flight <span class="hlt">icing</span> in 1996 where the state of knowledge concerning SLD was explored. One outcome of these meetings was an identified need to acquire SLD flight research data, particularly in the Great Lakes Region. The flight research data was needed by the FAA to develop a better understanding of the meteorological characteristics associated with SLD and facilitate an assessment of existing aircraft <span class="hlt">icing</span> certification regulations with respect to SLD. In response to this need, NASA, the Federal Aviation Administration (FAA), and the National Center for Atmospheric Research (NCAR) conducted a cooperative <span class="hlt">icing</span> flight research program to acquire SLD flight research data. The NASA Glenn Research Center's Twin Otter <span class="hlt">icing</span> research aircraft was flown throughout the Great Lakes region during the winters of 1996-97 and 1997-98 to acquire SLD <span class="hlt">icing</span> and meteorological data. The NASA Twin Otter was instrumented to measure cloud microphysical properties (particle size, LWC (Liquid Water Content), temperature, etc.), capture images of wing and tail <span class="hlt">ice</span> accretion, and then record the resultant effect on aircraft performance due to the <span class="hlt">ice</span> accretion. A satellite telephone link enabled the researchers onboard the Twin Otter to communicate with NCAR meteorologists. who provided real-time guidance into SLD <span class="hlt">icing</span> conditions. NCAR meteorologists also provided preflight SLD weather forecasts that were used to plan the research flights, and served as on-board researchers. This document contains an evaluation of the tools and techniques NCAR</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24977238','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24977238"><span id="translatedtitle">Wet and dry atmospheric depositions of inorganic nitrogen during plant growing <span class="hlt">season</span> in the coastal <span class="hlt">zone</span> of Yellow River Delta.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yu, Junbao; Ning, Kai; Li, Yunzhao; Du, Siyao; Han, Guangxuan; Xing, Qinghui; Wu, Huifeng; Wang, Guangmei; Gao, Yongjun</p> <p>2014-01-01</p> <p>The ecological problems caused by dry and wet deposition of atmospheric nitrogen have been widespread concern in the world. In this study, wet and dry atmospheric depositions were monitored in plant growing <span class="hlt">season</span> in the coastal <span class="hlt">zone</span> of the Yellow River Delta (YRD) using automatic sampling equipment. The results showed that SO4 (2-) and Na(+) were the predominant anion and cation, respectively, in both wet and dry atmospheric depositions. The total atmospheric nitrogen deposition was ~2264.24 mg m(-2), in which dry atmospheric nitrogen deposition was about 32.02%. The highest values of dry and wet atmospheric nitrogen deposition appeared in May and August, respectively. In the studied area, NO3 (-)-N was the main nitrogen form in dry deposition, while the predominant nitrogen in wet atmospheric deposition was NH4 (+)-N with ~56.51% of total wet atmospheric nitrogen deposition. The average monthly attribution rate of atmospheric deposition of NO3 (-)-N and NH4 (+)-N was ~31.38% and ~20.50% for the contents of NO3 (-)-N and NH4 (+)-N in 0-10 cm soil layer, respectively, suggested that the atmospheric nitrogen was one of main sources for soil nitrogen in coastal <span class="hlt">zone</span> of the YRD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3995312','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3995312"><span id="translatedtitle">Wet and Dry Atmospheric Depositions of Inorganic Nitrogen during Plant Growing <span class="hlt">Season</span> in the Coastal <span class="hlt">Zone</span> of Yellow River Delta</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Li, Yunzhao; Du, Siyao; Han, Guangxuan; Xing, Qinghui; Wu, Huifeng; Wang, Guangmei</p> <p>2014-01-01</p> <p>The ecological problems caused by dry and wet deposition of atmospheric nitrogen have been widespread concern in the world. In this study, wet and dry atmospheric depositions were monitored in plant growing <span class="hlt">season</span> in the coastal <span class="hlt">zone</span> of the Yellow River Delta (YRD) using automatic sampling equipment. The results showed that SO42− and Na+ were the predominant anion and cation, respectively, in both wet and dry atmospheric depositions. The total atmospheric nitrogen deposition was ~2264.24 mg m−2, in which dry atmospheric nitrogen deposition was about 32.02%. The highest values of dry and wet atmospheric nitrogen deposition appeared in May and August, respectively. In the studied area, NO3−–N was the main nitrogen form in dry deposition, while the predominant nitrogen in wet atmospheric deposition was NH4+–N with ~56.51% of total wet atmospheric nitrogen deposition. The average monthly attribution rate of atmospheric deposition of NO3−–N and NH4+–N was ~31.38% and ~20.50% for the contents of NO3−–N and NH4+–N in 0–10 cm soil layer, respectively, suggested that the atmospheric nitrogen was one of main sources for soil nitrogen in coastal <span class="hlt">zone</span> of the YRD. PMID:24977238</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3705479','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3705479"><span id="translatedtitle">Empirical Retrieval of Surface Melt Magnitude from Coupled MODIS Optical and Thermal Measurements over the Greenland <span class="hlt">Ice</span> Sheet during the 2001 Ablation <span class="hlt">Season</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lampkin, Derrick; Peng, Rui</p> <p>2008-01-01</p> <p>Accelerated <span class="hlt">ice</span> flow near the equilibrium line of west-central Greenland <span class="hlt">Ice</span> Sheet (GIS) has been attributed to an increase in infiltrated surface melt water as a response to climate warming. The assessment of surface melting events must be more than the detection of melt onset or extent. Retrieval of surface melt magnitude is necessary to improve understanding of <span class="hlt">ice</span> sheet flow and surface melt coupling. In this paper, we report on a new technique to quantify the magnitude of surface melt. Cloud-free dates of June 10, July 5, 7, 9, and 11, 2001 Moderate Resolution Imaging Spectroradiometer (MODIS) daily reflectance Band 5 (1.230-1.250μm) and surface temperature images rescaled to 1km over western Greenland were used in the retrieval algorithm. An optical-thermal feature space partitioned as a function of melt magnitude was derived using a one-dimensional thermal snowmelt model (SNTHERM89). SNTHERM89 was forced by hourly meteorological data from the Greenland Climate Network (GC-Net) at reference sites spanning dry snow, percolation, and wet snow <span class="hlt">zones</span> in the Jakobshavn drainage basin in western GIS. Melt magnitude or effective melt (E-melt) was derived for satellite composite periods covering May, June, and July displaying low fractions (0-1%) at elevations greater than 2500m and fractions at or greater than 15% at elevations lower than 1000m assessed for only the upper 5 cm of the snow surface. Validation of E-melt involved comparison of intensity to dry and wet <span class="hlt">zones</span> determined from QSCAT backscatter. Higher intensities (> 8%) were distributed in wet snow <span class="hlt">zones</span>, while lower intensities were grouped in dry <span class="hlt">zones</span> at a first order accuracy of ∼ ±2%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18524456','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18524456"><span id="translatedtitle"><span class="hlt">Seasonal</span> change detection of riparian <span class="hlt">zones</span> with remote sensing images and genetic programming in a semi-arid watershed.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Makkeasorn, Ammarin; Chang, Ni-Bin; Li, Jiahong</p> <p>2009-02-01</p> <p>Riparian <span class="hlt">zones</span> are deemed significant due to their interception capability of non-point source impacts and the maintenance of ecosystem integrity region wide. To improve classification and change detection of riparian buffers, this paper developed an evolutionary computational, supervised classification method--the RIparian Classification Algorithm (RICAL)--to conduct the <span class="hlt">seasonal</span> change detection of riparian <span class="hlt">zones</span> in a vast semi-arid watershed, South Texas. RICAL uniquely demonstrates an integrative effort to incorporate both vegetation indices and soil moisture images derived from LANDSAT 5 TM and RADARSAT-1 satellite images, respectively. First, an estimation of soil moisture based on RADARSAT-1 Synthetic Aperture Radar (SAR) images was conducted via the first-stage genetic programming (GP) practice. Second, for the statistical analyses and image classification, eight vegetation indices were prepared based on reflectance factors that were calculated as the response of the instrument on LANDSAT. These spectral vegetation indices were then independently used for discriminate analysis along with soil moisture images to classify the riparian <span class="hlt">zones</span> via the second-stage GP practice. The practical implementation was assessed by a case study in the Choke Canyon Reservoir Watershed (CCRW), South Texas, which is mostly agricultural and range land in a semi-arid coastal environment. To enhance the application potential, a combination of Iterative Self-Organizing Data Analysis Techniques (ISODATA) and maximum likelihood supervised classification was also performed for spectral discrimination and classification of riparian varieties comparatively. Research findings show that the RICAL algorithm may yield around 90% accuracy based on the unseen ground data. But using different vegetation indices would not significantly improve the final quality of the spectral discrimination and classification. Such practices may lead to the formulation of more effective management strategies</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24027985','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24027985"><span id="translatedtitle">[Study on <span class="hlt">seasonal</span> characteristics of thermal stratification in lacustrine <span class="hlt">zone</span> of Lake Qiandao].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dong, Chun-Ying; Yu, Zuo-Ming; Wu, Zhi-Xu; Wu, Chun-Jin</p> <p>2013-07-01</p> <p>Lake Qiandao is a typical subtropical man-made reservoir in China. The investigation on the <span class="hlt">seasonal</span> and vertical dynamics of water temperature, dissolved oxygen (DO), pH value, turbidity, photosynthetic available radiation (PAR) and chlorophyll a was conducted in 2011 in order to find out the physical characteristics of Lake Qiandao. The average surface water temperature ranged from 10.4 to 32.7 degrees C. A monomictic thermal stratification was observed in Lake Qiandao, initiating in April and lasting until December. The results showed that thermal stratification had influences on vertical distribution of DO, pH value, turbidity, PAR and chlorophyll a. Very strong stratification of DO was found, inducing lower oxygen concentration in the thermocline layer and temporal hypoxia in the bottom water. The maximum turbidity was found in the thermocline layer and the precipitation affected the surface turbidity value. Moreover, the chlorophyll a concentration was higher in the surface water and lower in the bottom water as found in this study, implying that water quality was affected by stratification. Besides, the maximum photosynthesis rate and algal growth rate were found at the depth 5-10 m below the water surface. Therefore, the results can provide theoretical support for the sampling and analysis of algal blooms in Lake Qiandao.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24377871','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24377871"><span id="translatedtitle"><span class="hlt">Seasonal</span> arsenic accumulation in stream sediments at a groundwater discharge <span class="hlt">zone</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>MacKay, Allison A; Gan, Ping; Yu, Ran; Smets, Barth F</p> <p>2014-01-21</p> <p><span class="hlt">Seasonal</span> changes in arsenic and iron accumulation rates were examined in the sediments of a brook that receives groundwater discharges of arsenic and reduced iron. Clean glass bead columns were deployed in sediments for known periods over the annual hydrologic cycle to monitor changes in arsenic and iron concentrations in bead coatings. The highest accumulation rates occurred during the dry summer period (July-October) when groundwater discharges were likely greatest at the sample locations. The intermediate flow period (October-March), with higher surface water levels, was associated with losses of arsenic and iron from bead column coatings at depths below 2-6 cm. Batch incubations indicated iron releases from solids to be induced by biological reduction of iron (oxy)hydroxide solids. Congruent arsenic releases during incubation were limited by the high arsenic sorption capacity (0.536 mg(As)/mg(Fe)) of unreacted iron oxide solids. The flooded spring (March-June) with high surface water flows showed the lowest arsenic and iron accumulation rates in the sediments. Comparisons of accumulation rates across a shoreline transect were consistent with greater rates at regions exposed above surface water levels for longer times and greater losses at locations submerged below surface water. Iron (oxy)hydroxide solids in the shallowest sediments likely serve as a passive barrier to sorb arsenic released to pore water at depth by biological iron reduction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813436V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813436V"><span id="translatedtitle">Contrasting Arctic and Antarctic sea <span class="hlt">ice</span> temperatures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vancoppenolle, Martin; Raphael, Marilyn; Rousset, Clément; Vivier, Frédéric; Moreau, Sébastien; Delille, Bruno; Tison, Jean-Louis</p> <p>2016-04-01</p> <p>Sea <span class="hlt">ice</span> temperature affects the sea <span class="hlt">ice</span> growth rate, heat content, permeability and habitability for <span class="hlt">ice</span> algae. Large-scale simulations with NEMO-LIM suggest large <span class="hlt">ice</span> temperature contrasts between the Arctic and the Antarctic sea <span class="hlt">ice</span>. First, Antarctic sea <span class="hlt">ice</span> proves generally warmer than in the Arctic, in particular during winter, where differences reach up to ~10°C. Second, the <span class="hlt">seasonality</span> of temperature is different among the two hemispheres: Antarctic <span class="hlt">ice</span> temperatures are 2-3°C higher in spring than they are in fall, whereas the opposite is true in the Arctic. These two key differences are supported by the available <span class="hlt">ice</span> core and mass balance buoys temperature observations, and can be attributed to differences in air temperature and snow depth. As a result, the <span class="hlt">ice</span> is found to be habitable and permeable over much larger areas and much earlier in late spring in the Antarctic as compared with the Arctic, which consequences on biogeochemical exchanges in the sea <span class="hlt">ice</span> <span class="hlt">zone</span> remain to be evaluated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Geomo.219..176B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Geomo.219..176B"><span id="translatedtitle"><span class="hlt">Seasonal</span>-scale abrasion and quarrying patterns from a two-dimensional <span class="hlt">ice</span>-flow model coupled to distributed and channelized subglacial drainage</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beaud, Flavien; Flowers, Gwenn E.; Pimentel, Sam</p> <p>2014-08-01</p> <p>Field data and numerical modeling show that glaciations have the potential either to enhance relief or to dampen topography. We aim to model the effect of the subglacial hydraulic system on spatiotemporal patterns of glacial erosion by abrasion and quarrying on time scales commensurate with drainage system fluctuations (e.g., <span class="hlt">seasonal</span> to annual). We use a numerical model that incorporates a dual-morphology subglacial drainage system coupled to a higher-order <span class="hlt">ice</span>-flow model and process-specific erosion laws. The subglacial drainage system allows for a dynamic transition between two morphologies: the distributed system, characterized by an increase in basal water pressure with discharge, and the channelized system, which exhibits a decrease in equilibrium water pressure with increasing discharge. We apply the model to a simple synthetic glacier geometry, drive it with prescribed meltwater input variations, and compute sliding and erosion rates over a <span class="hlt">seasonal</span> cycle. When both distributed and channelized systems are included, abrasion and sliding maxima migrate ~ 20% up-glacier compared to simulations with distributed drainage only. Power-law sliding generally yields to a broader response of abrasion to water pressure changes along the flowline compared to Coulomb-friction sliding. Multi-day variations in meltwater input elicit a stronger abrasion response than either diurnal- or <span class="hlt">seasonal</span> variations alone for the same total input volume. An increase in water input volume leads to increased abrasion. We find that <span class="hlt">ice</span> thickness commensurate with <span class="hlt">ice</span> sheet outlet glaciers can hinder the up-glacier migration of abrasion. Quarrying patterns computed with a recently published law differ markedly from calculated abrasion patterns, with effective pressure being a stronger determinant than sliding speeds of quarrying rates. These variations in calculated patterns of instantaneous erosion as a function of hydrology-, sliding-, and erosion-model formulation, as well as model</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.8410P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.8410P"><span id="translatedtitle">Environmental factors controlling transient and <span class="hlt">seasonal</span> changes of trace gases within shallow vadose <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pla, Concepcion; Galiana-Merino, Juan Jose; Cuezva, Soledad; Fernandez-Cortes, Angel; Garcia-Anton, Elena; Cuevas, Jaime; Cañaveras, Juan Carlos; Sanchez-Moral, Sergio; Benavente, David</p> <p>2014-05-01</p> <p>Shallow vadose environments below soil, mainly caves, show significant <span class="hlt">seasonal</span> and even daily variations in gas composition of ground air, which involves the exchange of large amounts of gases, e.g. greenhouse gases (GHGs) as CO2 or CH4, with the lower troposphere. To understand better the role of caves as a sink or depot of GHGs, geochemical tracing of air (atmosphere, soil and ground air) was performed at Rull cave (southeast Spain) by monitoring CH4, CO2 and the stable carbon isotopic delta13C[CO2] using cavity ring-down spectroscopy (CRDS). A comprehensive microclimatic monitoring of exterior and cave atmosphere was simultaneously conducted to GHGs-tracking, including factors as temperature, barometric pressure, relative humidity and concentration of CO2 and 222Rn. The analysis of the measured data allows understanding outgassing and isolation processes taking place in the karst cavity. Annual patterns of gases behaviour can be distinguished, depending on the prevailing relationship between outer atmosphere, indoor atmosphere and soil system. Cave air temperature fluctuates around 15.7 ºC and relative humidity remains higher than 96% the whole annual cycle. The mean concentration of 222Rn is 1584 Bq m-3 while CO2 remains 1921 ppm. When external temperature is higher of indoor temperature (April-October), the highest levels of both trace gases are reached, while levels drop to its lowest values in the coldest months. Preliminary results obtained show an annual variation in concentration of CO2 inside the cave between 3300 ppm and 900 ppm, whereas corresponding isotopic signal delta13CO2 varies between -24‰ and -21‰. The results have been studied by Keeling model that approximates the isotopic signal of the source contribution in a resulting air mix. The values registered inside the cave were represented joined to results for exterior air (average values round 410 ppm of CO2 and -9 ‰ for delta13C). Value obtained is -27‰ pointing to a high influence of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990SPIE.1302..225T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990SPIE.1302..225T"><span id="translatedtitle">Helicopter- and ship-based measurements of mesoscale ocean color and thermal features in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tanis, Fred J.; Manley, Thomas O.; Mitchell, Brian G.</p> <p>1990-09-01</p> <p>Eddies along the Polar Front/Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> (MIZ) in Fram Strait are thought to make important contributions to nutrient flux and stimulation of primary productivity. During the Coordinated Eastern Arctic Regional Experiment (CEAREX) helicopter-based measurements of upwelling radiance were made in four visible spectral bands and in the thermal IR across mesoscale features associated with the MIZ. These structures were mapped by flying a grid pattern over the ocean surface to define eddy boundaries. Subsequently, the area was also sampled vertically with CTD and spectral radiometer profilers. Data obtained from a single structure were integrated to construct a three dimensional picture of physical and optical properties. Volume modeling of temperature, salinity, and density fields obtained from CTD survey define the subsurface eddy structure and are in good agreement with infrared derived characteristics. Maximum temperature in the core was found to be four degrees higher than the surrounding water. Volume modeling further indicates that a subsurface layer of Arctic Intermediate Water is intrinsically associated with the surface expression of the eddy. The ratio of upwelling radiances, L(44l)/L(565), was found to be correlated to surface chlorophyll, particulate absorption coefficient, and in water determinations of L using the optical profiling system. The remote sensing reflectance ratio along with the IR sea surface temperature were found to be useful to detect the surface expression of the eddy and to indicate near surface biological and physical processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008DSRII..55.2266D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008DSRII..55.2266D"><span id="translatedtitle">Trophic interactions of macro-zooplankton (krill and amphipods) in the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> of the Barents Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dalpadado, Padmini; Yamaguchi, Atsushi; Ellertsen, Bjørnar; Johannessen, Signe</p> <p>2008-10-01</p> <p>The diets of krill and amphipods were examined using light microscopy on field-collected specimens from 2004 to 2005 from the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> of the northwestern Barents Sea, north and east of Spitsbergen. Stomach content analyses indicate dominant krill species to have a filter-feeding mode, whereas amphipods seem to be mainly raptorial feeders. The dominant krill, Thysanoessa inermis, is primarily regarded as an herbivore feeding mostly on diatoms. Alternatively, Thysanoessa longicaudata fed occasionally on calanoid copepods in addition to being a suspension feeder on phytoplankton. The largest of the krill species, Meganyctiphanes norvegica, showed a mixed diet with regular feeding on calanoid copepods and phytoplankton. The degree of carnivory varied between stations and was determined by examining the size and shape of the mandible of copepods. M. norvegica, with a total length of between 26 and 41 mm, had up to two copepods in their stomachs, with a mandible width of the copepods varying from 32 to 154 μm, corresponding, respectively, to a computed prosome length of 0.3 and 2.6 mm. Themisto libellula fed primarily on C3 and C4 copepodite stages of Calanus glacialis and Calanus hyperboreus, and up to three copepods were found in the stomach contents of T. libellula. Themisto abyssorum fed on herbivorous and omnivorous prey such as copepods and appendicularians. The presence of Metridia spp. and appendicularians, e.g., Oikopleura vanhoeffeni in the diet of T. abyssorum may indicate feeding in the deeper layers (>200 m).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=203433','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=203433"><span id="translatedtitle"><span class="hlt">Seasonal</span> Population Changes and Characterization of <span class="hlt">Ice</span>-Nucleating Bacteria in Farm Fields of Central Alberta †</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kaneda, Toshi</p> <p>1986-01-01</p> <p>During the summer of 1983 in central Alberta, changes in the bacterial population inhabiting the leaves of field beans (Phaseolus vulgaris L.) and canola (Brassica napus L. Altex) were studied to determine if <span class="hlt">ice</span>-nucleating bacteria were present on these plants. Three colony types (white, yellow, and peach-colored) were found on field beans and canola leaves. Approximately 25% of the isolates from the white colony group, which dominated the population, were <span class="hlt">ice</span>-nucleating bacteria. No <span class="hlt">ice</span>-nucleating bacteria were present on canola leaves. Out of a total of 76 <span class="hlt">ice</span>-nucleating bacteria isolated, 5 representative cultures were characterized in detail and identified as Pseudomonas fluorescens. The fatty acid composition of these cultures was essentially identical to that of typical P. fluorescens cultures and was altered by varying the growth temperature from 10 to 30°C. PMID:16347106</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C51E..08K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C51E..08K"><span id="translatedtitle">Direct Observations of Rapid Basal Melting and Bed Topography in the Grounding <span class="hlt">Zones</span> of the Dotson and Crosson <span class="hlt">Ice</span> Shelves, West Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khazendar, A.; Rignot, E. J.; Schroeder, D. M.; Seroussi, H. L.; Schodlok, M.; Scheuchl, B.; Sutterley, T. C.; Velicogna, I.</p> <p>2015-12-01</p> <p>Glaciological changes of the Dotson and Crosson <span class="hlt">ice</span> shelves and their tributary glaciers of Smith, Pope and Kohler are among the most noticeable in the Amundsen Sea Embayment region of West Antarctica. Here, we present sounding radar and laser altimetry observations of two aspects that are indispensable for understanding those changes: basal melting and bedrock topography in the grounding <span class="hlt">zones</span>. We find that Smith Glacier in particular thinned by a remarkably fast 300-490 m between the years 2002 and 2009. Its grounding line has retreated far enough to be now at 2000 m below sea level in a previously identified trench. All three glacier grounding lines have already retreated down steeper parts of their bedrocks to flatter terrains, plausibly contributing to the reported slowing down in the acceleration of their <span class="hlt">ice</span> volume discharges. The wider implications of the work emphasize the unprecedented perspectives that direct observation can offer of diverse grounding <span class="hlt">zone</span> structures and evolution scenarios.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EPSC...10..111P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPSC...10..111P"><span id="translatedtitle">Thermal cracking of CO2 slab <span class="hlt">ice</span> as the main driving force for albedo increase of the martian <span class="hlt">seasonal</span> polar caps</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Philippe, S.; Schmitt, B.; Beck, P.; Brissaud, O.</p> <p>2015-10-01</p> <p>Understanding the microphysical processes occuring on the Martian <span class="hlt">seasonal</span> cap is critical since their radiative properties can affect the martian climate. A well documented phenomenom is the albedo increase of the Martian <span class="hlt">seasonal</span> caps during spring, Fig.1. There are a lot of hypotheses that have been proposed as an explanation for this observation : the decrease of the CO2 grain size [2], a cleaning process of the CO2 slab that would imply either the sinking or the ejection of the dust contained in its volume ([1], [2], [5]), a water-layer accumulation on the top of the slab [5], the role played by aerosols [2] etc ... So far, no experimental simulations have been realized to discriminate between these processes. We designed an experiment to investigate the hypothesis of CO2 <span class="hlt">ice</span> grain size decrease through thermal cracking as well as that of dust segregation as the possible reasons for albedo increase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2197212','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2197212"><span id="translatedtitle"><span class="hlt">Seasonality</span> in a temperate <span class="hlt">zone</span> bird can be entrained by near equatorial photoperiods</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dawson, Alistair</p> <p>2006-01-01</p> <p>Birds use photoperiod to control the time of breeding and moult. However, it is unclear whether responses are dependent on absolute photoperiod, the direction and rate of change in photoperiod, or if photoperiod entrains a circannual clock. If starlings (Sturnus vulgaris) are kept on a constant photoperiod of 12 h light : 12 h darkness per day (12 L : 12 D), then they can show repeated cycles of gonadal maturation, regression and moult, which is evidence for a circannual clock. In this study, starlings kept on constant 11.5 L : 12.5 D for 4 years or 12.5 L : 11.5 D for 3 years showed no circannual cycles in gonadal maturation or moult. So, if there is a circannual clock, it is overridden by a modest deviation in photoperiod from 12 L : 12 D. The responses to 11.5 L : 12.5 D and 12.5 L : 11.5 D were very different, the former perceived as a short photoperiod (birds were photosensitive for most of the time) and the latter as a long photoperiod (birds remained permanently photorefractory). Starlings were then kept on a schedule which ranged from 11.5 L : 12.5 D in mid-winter to 12.5 L : 11.5 D in mid-summer (simulating the annual cycle at 9 °N) for 3 years. These birds entrained precisely to calendar time and changes in testicular size and moult were similar to those of birds under a simulated cycle at 52 °N. These data show that birds are very sensitive to changes in photoperiod but that they do not simply respond to absolute photoperiod nor can they rely on a circannual clock. Instead, birds appear to respond to the shape of the annual change in photoperiod. This proximate control could operate from near equatorial latitudes and would account for similar <span class="hlt">seasonal</span> timing in individuals of a species over a wide range of latitudes. PMID:17254997</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25085426','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25085426"><span id="translatedtitle">The impact of land use and <span class="hlt">season</span> on the riverine transport of mercury into the marine coastal <span class="hlt">zone</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Saniewska, Dominika; Bełdowska, Magdalena; Bełdowski, Jacek; Saniewski, Michał; Szubska, Marta; Romanowski, Andrzej; Falkowska, Lucyna</p> <p>2014-11-01</p> <p>In Mediterranean seas and coastal <span class="hlt">zones</span>, rivers can be the main source of mercury (Hg). Catchment management therefore affects the load of Hg reaching the sea with surface runoff. The major freshwater inflows to the Baltic Sea consist of large rivers. However, their systems are complex and identification of factors affecting the outflow of Hg from its catchments is difficult. For this reason, a study into the impact of watershed land use and <span class="hlt">season</span> on mercury biogeochemistry and transport in rivers was performed along two small rivers which may be considered typical of the southern Baltic region. Neither of these rivers are currently impacted by industrial effluents, thus allowing assessment of the influence of catchment terrain and <span class="hlt">season</span> on Hg geochemistry. The study was performed between June 2008 and May 2009 at 13 sampling points situated at different terrain types within the catchments (forest, wetland, agriculture and urban). Hg analyses were conducted by CVAFS. Arable land erosion was found to be an important source of Hg to the aquatic system, similar to urban areas. Furthermore, inflows of untreated storm water discharge resulted in a fivefold increase of Hg concentration in the rivers. The highest Hg concentration in the urban runoff was observed with the greatest amount of precipitation during summer. Moderate rainfalls enhance the inflow of bioavailable dissolved mercury into water bodies. Despite the lack of industrial effluents entering the rivers directly, the sub-catchments with anthropogenic land use were important sources of Hg in the rivers. This was caused by elution of metal, deposited in soils over the past decades, into the rivers. The obtained results are especially important in the light of recent environmental conscience regulations, enforcing the decrease of pollution by Baltic countries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......652S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......652S"><span id="translatedtitle">Coupling fast all-<span class="hlt">season</span> soil strength land surface model with weather research and forecasting model to assess low-level <span class="hlt">icing</span> in complex terrain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sines, Taleena R.</p> <p></p> <p><span class="hlt">Icing</span> poses as a severe hazard to aircraft safety with financial resources and even human lives hanging in the balance when the decision to ground a flight must be made. When analyzing the effects of <span class="hlt">ice</span> on aviation, a chief cause for danger is the disruption of smooth airflow, which increases the drag force on the aircraft therefore decreasing its ability to create lift. The Weather Research and Forecast (WRF) model Advanced Research WRF (WRF-ARW) is a collaboratively created, flexible model designed to run on distributed computing systems for a variety of applications including forecasting research, parameterization research, and real-time numerical weather prediction. Land-surface models, one of the physics options available in the WRF-ARW, output surface heat and moisture flux given radiation, precipitation, and surface properties such as soil type. The Fast All-<span class="hlt">Season</span> Soil STrength (FASST) land-surface model was developed by the U.S. Army ERDC-CRREL in Hanover, New Hampshire. Designed to use both meteorological and terrain data, the model calculates heat and moisture within the surface layer as well as the exchange of these parameters between the soil, surface elements (such as snow and vegetation), and atmosphere. Focusing on the Presidential Mountain Range of New Hampshire under the NASA Experimental Program to Stimulate Competitive Research (EPSCoR) <span class="hlt">Icing</span> Assessments in Cold and Alpine Environments project, one of the main goals is to create a customized, high resolution model to predict and assess <span class="hlt">ice</span> accretion in complex terrain. The purpose of this research is to couple the FASST land-surface model with the WRF to improve <span class="hlt">icing</span> forecasts in complex terrain. Coupling FASST with the WRF-ARW may improve <span class="hlt">icing</span> forecasts because of its sophisticated approach to handling processes such as meltwater, freezing, thawing, and others that would affect the water and energy budget and in turn affect <span class="hlt">icing</span> forecasts. Several transformations had to take place in order</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22181553','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22181553"><span id="translatedtitle">Suppression of the water <span class="hlt">ice</span> and snow albedo feedback on planets orbiting red dwarf stars and the subsequent widening of the habitable <span class="hlt">zone</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Joshi, Manoj M; Haberle, Robert M</p> <p>2012-01-01</p> <p>M stars comprise 80% of main sequence stars, so their planetary systems provide the best chance for finding habitable planets, that is, those with surface liquid water. We have modeled the broadband albedo or reflectivity of water <span class="hlt">ice</span> and snow for simulated planetary surfaces orbiting two observed red dwarf stars (or M stars), using spectrally resolved data of Earth's cryosphere. The gradual reduction of the albedos of snow and <span class="hlt">ice</span> at wavelengths greater than 1 μm, combined with M stars emitting a significant fraction of their radiation at these same longer wavelengths, means that the albedos of <span class="hlt">ice</span> and snow on planets orbiting M stars are much lower than their values on Earth. Our results imply that the <span class="hlt">ice</span>/snow albedo climate feedback is significantly weaker for planets orbiting M stars than for planets orbiting G-type stars such as the Sun. In addition, planets with significant <span class="hlt">ice</span> and snow cover will have significantly higher surface temperatures for a given stellar flux if the spectral variation of cryospheric albedo is considered, which in turn implies that the outer edge of the habitable <span class="hlt">zone</span> around M stars may be 10-30% farther away from the parent star than previously thought.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.2532M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.2532M"><span id="translatedtitle">On the feasibility of cirrus cloud thinning: Dependence of homo- and heterogeneous <span class="hlt">ice</span> nucleation on latitude and <span class="hlt">season</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mitchell, David; Garnier, Anne; Avery, Melody</p> <p>2015-04-01</p> <p>While GCM testing of cirrus cloud climate engineering (CE) reveals some advantages over stratospheric aerosol injection, cirrus CE will not work when <span class="hlt">ice</span> is primarily formed through heterogeneous nucleation for T < -38°C. Field campaigns have shown that <span class="hlt">ice</span> in cold cirrus is generally produced heterogeneously, but these campaigns have not addressed the cirrus at high latitudes that would determine the effectiveness of cirrus CE. This presentation introduces a new understanding of the satellite retrieved "effective absorption optical depth ratio", or βeff, based on the 12.05 and 10.60 μm channels of the imaging infrared radiometer (IIR) aboard the CALIPSO satellite. Using βeff calculations from in situ data, it is found that βeff is tightly related to the N/IWC ratio, where N = <span class="hlt">ice</span> particle number concentration and IWC = <span class="hlt">ice</span> water content. This is because N is primarily determined by the smallest <span class="hlt">ice</span> particles, and βeff is primarily due to differences in wave resonance (i.e. photon tunneling) absorption, a process that is only significant when <span class="hlt">ice</span> particle maximum dimension D < ~ 60 μm (i.e. when wavelength and effective particle size are comparable). Thus βeff is a measure of the concentration of small (D < 60 μm) <span class="hlt">ice</span> crystals relative to the concentration of larger <span class="hlt">ice</span> particles. Since homogeneous <span class="hlt">ice</span> nucleation generally results in N > 500 liter-1, with a relatively high concentration of small <span class="hlt">ice</span> crystals, βeff may be used to determine when homogeneous nucleation dominates in a region for T < -38°C. Satellite retrievals of βeff from anvil cirrus having N > 500 liter-1 (based on co-located/coincident in situ measurements) suggest that homogeneous nucleation dominates when βeff > 1.15 ± 0.05. A global analysis of βeff was conducted for the boreal summer (July-Aug.) and winter (Jan.-Feb.) of 2007 and 2008, respectively. Using βeff to discriminate between regions of homo- and heterogeneous <span class="hlt">ice</span> nucleation for cirrus clouds having emissivities between</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRC..120.8327H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRC..120.8327H"><span id="translatedtitle">Short-term sea <span class="hlt">ice</span> forecasting: An assessment of <span class="hlt">ice</span> concentration and <span class="hlt">ice</span> drift forecasts using the U.S. Navy's Arctic Cap Nowcast/Forecast System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hebert, David A.; Allard, Richard A.; Metzger, E. Joseph; Posey, Pamela G.; Preller, Ruth H.; Wallcraft, Alan J.; Phelps, Michael W.; Smedstad, Ole Martin</p> <p>2015-12-01</p> <p>In this study the forecast skill of the U.S. Navy operational Arctic sea <span class="hlt">ice</span> forecast system, the Arctic Cap Nowcast/Forecast System (ACNFS), is presented for the period February 2014 to June 2015. ACNFS is designed to provide short term, 1-7 day forecasts of Arctic sea <span class="hlt">ice</span> and ocean conditions. Many quantities are forecast by ACNFS; the most commonly used include <span class="hlt">ice</span> concentration, <span class="hlt">ice</span> thickness, <span class="hlt">ice</span> velocity, sea surface temperature, sea surface salinity, and sea surface velocities. <span class="hlt">Ice</span> concentration forecast skill is compared to a persistent <span class="hlt">ice</span> state and historical sea <span class="hlt">ice</span> climatology. Skill scores are focused on areas where <span class="hlt">ice</span> concentration changes by ±5% or more, and are therefore limited to primarily the marginal <span class="hlt">ice</span> <span class="hlt">zone</span>. We demonstrate that ACNFS forecasts are skilful compared to assuming a persistent <span class="hlt">ice</span> state, especially beyond 24 h. ACNFS is also shown to be particularly skilful compared to a climatologic state for forecasts up to 102 h. Modeled <span class="hlt">ice</span> drift velocity is compared to observed buoy data from the International Arctic Buoy Programme. A <span class="hlt">seasonal</span> bias is shown where ACNFS is slower than IABP velocity in the summer months and faster in the winter months. In February 2015, ACNFS began to assimilate a blended <span class="hlt">ice</span> concentration derived from Advanced Microwave Scanning Radiometer 2 (AMSR2) and the Interactive Multisensor Snow and <span class="hlt">Ice</span> Mapping System (IMS). Preliminary results show that assimilating AMSR2 blended with IMS improves the short-term forecast skill and <span class="hlt">ice</span> edge location compared to the independently derived National <span class="hlt">Ice</span> Center <span class="hlt">Ice</span> Edge product.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25280551','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25280551"><span id="translatedtitle">Discovery of bacterial polyhydroxyalkanoate synthase (PhaC)-encoding genes from <span class="hlt">seasonal</span> Baltic Sea <span class="hlt">ice</span> and cold estuarine waters.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pärnänen, Katariina; Karkman, Antti; Virta, Marko; Eronen-Rasimus, Eeva; Kaartokallio, Hermanni</p> <p>2015-01-01</p> <p>Polyhydroxyalkanoates (PHAs) are macromolecules produced by bacteria as means for storing carbon and energy in intracellular granules. PHAs have physical properties similar to those of plastics and have become of interest to industry as materials for environmentally friendly bioplastic production. There is an ongoing search for new PHA-producing bacterial strains and PHA-synthesizing enzymes tolerating extreme conditions to find ways of producing PHAs at cold temperatures and high solute concentrations. Moreover, the study of PHA producers in the sea-<span class="hlt">ice</span> biome can aid in understanding the microbial ecology of carbon cycling in <span class="hlt">ice</span>-associated ecosystems. In this study, PHA producers and PHA synthase genes were examined under the extreme environmental conditions of sea <span class="hlt">ice</span> and cold seawater to find evidence of PHA production in an environment requiring adaptation to high salinity and cold temperatures. Sea <span class="hlt">ice</span> and cold estuarine water samples were collected from the northern Baltic Sea and evidence of PHA production was gathered, using microscopy with Nile Blue A staining of PHA-granules and PCR assays detecting PHA-synthesis genes. The PHA granules and PHA synthases were found at all sampling locations, in both sea <span class="hlt">ice</span> and water, and throughout the sampling period spanning over 10 years. Our study shows, for the first time, that PHA synthesis occurs in Baltic Sea cold-adapted bacteria in their natural environment, which makes the Baltic Sea and its cold environments an interesting choice in the quest for PHA-synthesizing bacteria and synthesis genes. PMID:25280551</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C51A0675B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C51A0675B"><span id="translatedtitle">Arctic Sea <span class="hlt">Ice</span> Reemergence Mechanisms in a Model Hierarchy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bushuk, M.; Giannakis, D.</p> <p>2015-12-01</p> <p>Lagged correlation analysis of Arctic sea <span class="hlt">ice</span> area anomalies reveals that melt <span class="hlt">season</span> sea <span class="hlt">ice</span> anomalies tend to recur the following growth <span class="hlt">season</span>, and growth <span class="hlt">season</span> anomalies tend to recur the following melt <span class="hlt">season</span>. In this work, the regional and temporal characteristics of this phenomenon, termed sea-<span class="hlt">ice</span> reemergence, are investigated in a hierarchy of climate models. Coupled nonlinear Laplacian spectral analysis (NLSA), a multivariate data analysis technique, is used to study the covariability of Arctic sea-<span class="hlt">ice</span> concentration (SIC), sea-surface temperature (SST), sea-level pressure (SLP), and sea-<span class="hlt">ice</span> thickness (SIT). Two mechanisms related to melt <span class="hlt">season</span> to growth <span class="hlt">season</span> reemergence are identified: (1) An SST-SIC mechanism, related to local imprinting and persistence of SST anomalies in the <span class="hlt">seasonal</span> <span class="hlt">ice</span> <span class="hlt">zones</span>, and (2) an SLP-SIC mechanism, related to winter-to-winter regime persistence of large-scale SLP teleconnection patterns. An SIT-SIC growth <span class="hlt">season</span> to melt <span class="hlt">season</span> reemergence mechanism is also identified, related to winter persistence of SIT anomalies in the central Arctic. The representation of these mechanisms is investigated using the model hierarchy to determine the relative roles of the ocean, atmosphere, and sea <span class="hlt">ice</span> itself in producing reemergence. It is found that the SST-based and SIT-based mechanisms can exist as stand-alone processes, whereas the SLP mechanism cannot. Dynamical feedback from the ocean to the atmosphere is found to be essential in creating large-scale organized patterns of SIC-SLP covariability. A set of reemergence metrics is introduced, by which one can judge the amplitude and phase of reemergence events and associated mechanisms.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26907839','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26907839"><span id="translatedtitle"><span class="hlt">Seasonal</span> Changes in Whole Body and Regional Body Composition Profiles of Elite Collegiate <span class="hlt">Ice</span>-Hockey Players.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Prokop, Neal W; Reid, Ryan E R; Andersen, Ross E</p> <p>2016-03-01</p> <p>The monitoring of a collegiate hockey player's body composition can reflect fitness characteristics and may help players, coaches, or strength and conditioning specialists optimize physiologic gains during an off-<span class="hlt">season</span>, whereas simultaneously preventing performance decrements in-<span class="hlt">season</span>. The purpose of the study was to investigate changes in whole-body and regional-body composition of fat and lean tissue. The body composition profiles of 19 elite Canadian collegiate hockey players were assessed using dual energy X-ray absorptiometry. Players completed end-of-<span class="hlt">season</span>, preseason, and midseason assessments with questionnaires relating to their off-<span class="hlt">season</span> and in-<span class="hlt">season</span> training. Statistically significant changes in body composition profiles were observed between the different time points because players showed various tissue gains and losses depending on the region assessed. Overall, players gained (1.38 kg, p ≤ 0.01) and lost (0.79 kg, p ≤ 0.01) fat tissue during the off-<span class="hlt">season</span> and in-<span class="hlt">season</span>, respectively. Players also showed a significant gain of leg lean tissue (0.29 kg, p = 0.02) and loss of arm tissue mass (-0.25 kg, p = 0.02) during the first-half of the competitive <span class="hlt">season</span>. Several correlations emerged that may provide insight into potential trends that could be more pronounced during longer and more demanding schedules. Collegiate hockey players show changes in body composition during the off-<span class="hlt">season</span> and in-<span class="hlt">season</span>. The understanding of body composition profiles, body composition fluctuations, and potential variables that may influence the composition of collegiate hockey players can help coaches and athletic programs tailor their team's training, nutrition, lifestyle, and informative resources to further support their athletes. PMID:26907839</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26907839','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26907839"><span id="translatedtitle"><span class="hlt">Seasonal</span> Changes in Whole Body and Regional Body Composition Profiles of Elite Collegiate <span class="hlt">Ice</span>-Hockey Players.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Prokop, Neal W; Reid, Ryan E R; Andersen, Ross E</p> <p>2016-03-01</p> <p>The monitoring of a collegiate hockey player's body composition can reflect fitness characteristics and may help players, coaches, or strength and conditioning specialists optimize physiologic gains during an off-<span class="hlt">season</span>, whereas simultaneously preventing performance decrements in-<span class="hlt">season</span>. The purpose of the study was to investigate changes in whole-body and regional-body composition of fat and lean tissue. The body composition profiles of 19 elite Canadian collegiate hockey players were assessed using dual energy X-ray absorptiometry. Players completed end-of-<span class="hlt">season</span>, preseason, and midseason assessments with questionnaires relating to their off-<span class="hlt">season</span> and in-<span class="hlt">season</span> training. Statistically significant changes in body composition profiles were observed between the different time points because players showed various tissue gains and losses depending on the region assessed. Overall, players gained (1.38 kg, p ≤ 0.01) and lost (0.79 kg, p ≤ 0.01) fat tissue during the off-<span class="hlt">season</span> and in-<span class="hlt">season</span>, respectively. Players also showed a significant gain of leg lean tissue (0.29 kg, p = 0.02) and loss of arm tissue mass (-0.25 kg, p = 0.02) during the first-half of the competitive <span class="hlt">season</span>. Several correlations emerged that may provide insight into potential trends that could be more pronounced during longer and more demanding schedules. Collegiate hockey players show changes in body composition during the off-<span class="hlt">season</span> and in-<span class="hlt">season</span>. The understanding of body composition profiles, body composition fluctuations, and potential variables that may influence the composition of collegiate hockey players can help coaches and athletic programs tailor their team's training, nutrition, lifestyle, and informative resources to further support their athletes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012473','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012473"><span id="translatedtitle">Arctic continental shelf morphology related to sea-<span class="hlt">ice</span> zonation, Beaufort Sea, Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Reimnitz, E.; Toimil, L.; Barnes, P.</p> <p>1978-01-01</p> <p> processes. A proposed <span class="hlt">ice</span> zonation, including <span class="hlt">zones</span> of (1) bottom-fast <span class="hlt">ice</span>, (2) floating fast <span class="hlt">ice</span>, (3) stamukhi, and (4) <span class="hlt">seasonal</span> pack <span class="hlt">ice</span>, emphasizes <span class="hlt">ice</span> interaction with the shelf surface and differs from previous zonation. Certain aspects of the results reported here are directly applicable to planned offshore developments in the Prudhoe Bay oil field. Properly placed artificial structures similar to offshore shoals should be able to withstand the forces of the <span class="hlt">ice</span>, serve to modify the observed <span class="hlt">ice</span> zonation, and might be used to make the environment less hostile to human activities. ?? 1978.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.C13H..08C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.C13H..08C"><span id="translatedtitle">Accumulation Rates in the Dry Snow <span class="hlt">Zone</span> of the Greenland <span class="hlt">Ice</span> Sheet Inferred from L-band InSAR Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, A. C.; Zebker, H. A.</p> <p>2012-12-01</p> <p>The Greenland <span class="hlt">ice</span> sheet contains about 2.9 million km3 of <span class="hlt">ice</span> and would raise global sea levels by about 7.1 m if it melted completely. Two unusually large iceberg calving events at Petermann Glacier in the past several years, along with the unusually large extent of <span class="hlt">ice</span> sheet melt this summer point to the relevance of understanding the mass balance of the Greenland <span class="hlt">ice</span> sheet. In this study, we use data from the PALSAR instrument aboard the ALOS satellite to form L-band (23-centimeter carrier wavelength) InSAR images of the dry snow <span class="hlt">zone</span> of the Greenland <span class="hlt">ice</span> sheet. We form geocoded differential interferograms, using the <span class="hlt">ice</span> sheet elevation model produced by Howat et.al. [1]. By applying phase and radiometric calibration, we can examine interferograms formed between any pair of transmit and receive polarization channels. In co-polarized interferograms, the InSAR correlation ranges from about 0.35 at the summit (38.7 deg W, 73.0 deg N) where accumulation is about 20 cm w.e./yr to about 0.70 at the north-eastern part of the dry snow <span class="hlt">zone</span> (35.1 deg W, 77.1 deg N), where accumulation is about 11.7 cm w.e./yr. Cross-polarized interferograms show similar geographic variation with overall lower correlation. We compare our InSAR data with in-situ measurements published by Bales et.al. [2]. We examine the applicability of dense-medium radiative transfer electromagnetic scattering models for estimating accumulation rates from L-band InSAR data. The large number and broad coverage of ALOS scenes acquired between 2007 and 2009 with good InSAR coherence at 46-day repeat times and 21.5 degree incidence angles gives us the opportunity to examine the empirical relationship between in-situ accumulation rate observations and the polarimetric InSAR correlation and radar brightness at this particular imaging geometry. This helps us quantify the accuracy of accumulation rates estimated from InSAR data. In some regions, 46-day interferograms acquired in the winters of several consecutive</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014QSRv...88..125E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014QSRv...88..125E"><span id="translatedtitle">Glacially-megalineated limestone terrain of Anticosti Island, Gulf of St. Lawrence, Canada; onset <span class="hlt">zone</span> of the Laurentian Channel <span class="hlt">Ice</span> Stream</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eyles, Nick; Putkinen, Niko</p> <p>2014-03-01</p> <p>Anticosti is a large elongate island (240 km long, 60 km wide) in eastern Canada within the northern part of a deep water trough (Gulf of St. Lawrence) that terminates at the Atlantic continental shelf edge. The island's Pleistocene glaciological significance is that its long axis lay transverse to <span class="hlt">ice</span> from the Quebec and Labrador sectors of the Laurentide <span class="hlt">Ice</span> Sheet moving south from the relatively high-standing Canadian Shield. Recent glaciological reconstructions place a fast-flowing <span class="hlt">ice</span> stream along the axis of the Gulf of St. Lawrence but supporting geologic evidence in terms of recognizing its hard-bedded onset <span class="hlt">zone</span> and downstream streamlined soft bed is limited. Anticosti Island consists of gently southward-dipping limestone plains composed of Ordovician and Silurian limestones (Vaureal, Becscie and Jupiter formations) with north-facing escarpments transverse to regional <span class="hlt">ice</span> flow. Glacial deposits are largely absent and limestone plains in the higher central plateau of the island retain a relict apparently ‘preglacial’ drainage system consisting of deeply-incised dendritic bedrock valleys. In contrast, the bedrock geomorphology of the lower lying western and eastern limestone plains of the island is strikingly different having been extensively modified by glacial erosion. Escarpments are glacially megalineated with a distinct ‘zig-zag’ planform reflecting northward-projecting bullet-shaped ‘noses’ (identified as rock drumlins) up to 2 km wide at their base and 4 km in length with rare megagrooved upper surfaces. Drumlins are separated by southward-closing, funnel-shaped ‘through valleys’ where former dendritic valleys have been extensively altered by the streaming of basal <span class="hlt">ice</span> through gaps in the escarpments. Glacially-megalineated bedrock terrain such as on the western and eastern flanks of Anticosti Island is elsewhere associated with the hard-bedded onset <span class="hlt">zones</span> of fast flowing <span class="hlt">ice</span> streams and provides important ground truth for the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19052630','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19052630"><span id="translatedtitle"><span class="hlt">Seasonal</span> dynamics of SAR11 populations in the euphotic and mesopelagic <span class="hlt">zones</span> of the northwestern Sargasso Sea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carlson, Craig A; Morris, Robert; Parsons, Rachel; Treusch, Alexander H; Giovannoni, Stephen J; Vergin, Kevin</p> <p>2009-03-01</p> <p>Bacterioplankton belonging to the SAR11 clade of a-proteobacteria were counted by fluorescence in situ hybridization (FISH) over eight depths in the surface 300 m at the Bermuda Atlantic Time-series Study (BATS) site from 2003 to 2005. SAR11 are dominant heterotrophs in oligotrophic systems; thus, resolving their temporal dynamics can provide important insights to the cycling of organic and inorganic nutrients. This quantitative time-series data revealed distinct annual distribution patterns of SAR11 abundance in the euphotic (0-120) and upper mesopelagic (160-300 m) <span class="hlt">zones</span> that were reproducibly correlated with <span class="hlt">seasonal</span> mixing and stratification of the water column. Terminal restriction fragment length polymorphism (T-RFLP) data generated from a decade of samples collected at BATS were combined with the FISH data to model the annual dynamics of SAR11 subclade populations. 16S rRNA gene clone libraries were constructed to verify the correlation of the T-RFLP data with SAR11 clade structure. Clear vertical and temporal transitions were observed in the dominance of three SAR11 ecotypes. The mechanisms that lead to shifts between the different SAR11 populations are not well understood, but are probably a consequence of finely tuned physiological adaptations that partition the populations along physical and chemical gradients in the ecosystem. The correlation between evolutionary descent and temporal/spatial patterns we describe, confirmed that a minimum of three SAR11 ecotypes occupy the Sargasso Sea surface layer, and revealed new details of their population dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3712106','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3712106"><span id="translatedtitle"><span class="hlt">Seasonal</span> Distribution of Ticks in Four Habitats near the Demilitarized <span class="hlt">Zone</span>, Gyeonggi-do (Province), Republic of Korea</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chong, Sung Tae; Kim, Heung Chul; Lee, In-Yong; Kollars, Thomas M.; Sancho, Alfredo R.; Sames, William J.; Chae, Joon-Seok</p> <p>2013-01-01</p> <p>This study describes the <span class="hlt">seasonal</span> distribution of larvae, nymph, and adult life stages for 3 species of ixodid ticks collected by tick drag and sweep methods from various habitats in the Republic of Korea (ROK). Grasses less than 0.5 m in height, including herbaceous and crawling vegetation, and deciduous, conifer, and mixed forests with abundant leaf/needle litter were surveyed at United States (US) and ROK operated military training sites and privately owned lands near the demilitarized <span class="hlt">zone</span> from April-October, 2004 and 2005. Haemaphysalis longicornis Neumann adults and nymphs were more frequently collected from April-August, while those of Haemaphysalis flava Neumann and Ixodes nipponensis Kitaoka and Saito were collected more frequently from April-July and again during October. H. longicornis was the most frequently collected tick in grass habitats (98.9%), while H. flava was more frequently collected in deciduous (60.2%) and conifer (57.4%) forest habitats. While more H. flava (54.1%) were collected in mixed forest habitats than H. longicornis (35.2%), the differences were not significant. I. nipponensis was more frequently collected from conifer (mean 8.8) compared to deciduous (3.2) and mixed (2.4) forests. PMID:23864743</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23864743','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23864743"><span id="translatedtitle"><span class="hlt">Seasonal</span> distribution of ticks in four habitats near the demilitarized <span class="hlt">zone</span>, Gyeonggi-do (Province), Republic of Korea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chong, Sung Tae; Kim, Heung Chul; Lee, In-Yong; Kollars, Thomas M; Sancho, Alfredo R; Sames, William J; Chae, Joon-Seok; Klein, Terry A</p> <p>2013-06-01</p> <p>This study describes the <span class="hlt">seasonal</span> distribution of larvae, nymph, and adult life stages for 3 species of ixodid ticks collected by tick drag and sweep methods from various habitats in the Republic of Korea (ROK). Grasses less than 0.5 m in height, including herbaceous and crawling vegetation, and deciduous, conifer, and mixed forests with abundant leaf/needle litter were surveyed at United States (US) and ROK operated military training sites and privately owned lands near the demilitarized <span class="hlt">zone</span> from April-October, 2004 and 2005. Haemaphysalis longicornis Neumann adults and nymphs were more frequently collected from April-August, while those of Haemaphysalis flava Neumann and Ixodes nipponensis Kitaoka and Saito were collected more frequently from April-July and again during October. H. longicornis was the most frequently collected tick in grass habitats (98.9%), while H. flava was more frequently collected in deciduous (60.2%) and conifer (57.4%) forest habitats. While more H. flava (54.1%) were collected in mixed forest habitats than H. longicornis (35.2%), the differences were not significant. I. nipponensis was more frequently collected from conifer (mean 8.8) compared to deciduous (3.2) and mixed (2.4) forests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22357025','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22357025"><span id="translatedtitle">The effect of planets beyond the <span class="hlt">ice</span> line on the accretion of volatiles by habitable-<span class="hlt">zone</span> rocky planets</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Quintana, Elisa V.; Lissauer, Jack J.</p> <p>2014-05-01</p> <p>Models of planet formation have shown that giant planets have a large impact on the number, masses, and orbits of terrestrial planets that form. In addition, they play an important role in delivering volatiles from material that formed exterior to the snow line (the region in the disk beyond which water <span class="hlt">ice</span> can condense) to the inner region of the disk where terrestrial planets can maintain liquid water on their surfaces. We present simulations of the late stages of terrestrial planet formation from a disk of protoplanets around a solar-type star and we include a massive planet (from 1 M {sub ⊕} to 1 M {sub J}) in Jupiter's orbit at ∼5.2 AU in all but one set of simulations. Two initial disk models are examined with the same mass distribution and total initial water content, but with different distributions of water content. We compare the accretion rates and final water mass fraction of the planets that form. Remarkably, all of the planets that formed in our simulations without giant planets were water-rich, showing that giant planet companions are not required to deliver volatiles to terrestrial planets in the habitable <span class="hlt">zone</span>. In contrast, an outer planet at least several times the mass of Earth may be needed to clear distant regions of debris truncating the epoch of frequent large impacts. Observations of exoplanets from radial velocity surveys suggest that outer Jupiter-like planets may be scarce, therefore, the results presented here suggest that there may be more habitable planets residing in our galaxy than previously thought.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GBioC..30.1054T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GBioC..30.1054T"><span id="translatedtitle">Eroding permafrost coasts release low amounts of dissolved organic carbon (DOC) from ground <span class="hlt">ice</span> into the nearshore <span class="hlt">zone</span> of the Arctic Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tanski, George; Couture, Nicole; Lantuit, Hugues; Eulenburg, Antje; Fritz, Michael</p> <p>2016-07-01</p> <p><span class="hlt">Ice</span>-rich permafrost coasts in the Arctic are highly sensitive to climate warming and erode at a pace that exceeds the global average. Permafrost coasts deliver vast amounts of organic carbon into the nearshore <span class="hlt">zone</span> of the Arctic Ocean. Numbers on flux exist for particulate organic carbon (POC) and total or soil organic carbon (TOC, SOC). However, they do not exist for dissolved organic carbon (DOC), which is known to be highly bioavailable. This study aims to estimate DOC stocks in coastal permafrost as well as the annual flux into the ocean. DOC concentrations in ground <span class="hlt">ice</span> were analyzed along the <span class="hlt">ice</span>-rich Yukon coast (YC) in the western Canadian Arctic. The annual DOC flux was estimated using available numbers for coast length, cliff height, annual erosion rate, and volumetric <span class="hlt">ice</span> content in different stratigraphic horizons. Our results showed that DOC concentrations in ground <span class="hlt">ice</span> range between 0.3 and 347.0 mg L-1 with an estimated stock of 13.6 ± 3.0 g m-3 along the YC. An annual DOC flux of 54.9 ± 0.9 Mg yr-1 was computed. These DOC fluxes are low compared to POC and SOC fluxes from coastal erosion or POC and DOC fluxes from Arctic rivers. We conclude that DOC fluxes from permafrost coasts play a secondary role in the Arctic carbon budget. However, this DOC is assumed to be highly bioavailable. We hypothesize that DOC from coastal erosion is important for ecosystems in the Arctic nearshore <span class="hlt">zones</span>, particularly in summer when river discharge is low, and in areas where rivers are absent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.H53K..06O&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.H53K..06O&link_type=ABSTRACT"><span id="translatedtitle">Critical <span class="hlt">zone</span> co-evolution: evidence that weathering and consequent <span class="hlt">seasonal</span> rock moisture storage leads to a mixed forest canopy of conifer and evergreen broadleaf trees</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oshun, J.; Dietrich, W. E.; Dawson, T. E.; Rempe, D. M.; Fung, I. Y.</p> <p>2014-12-01</p> <p>Despite recent studies demonstrating the importance of rock moisture as a source of water to vegetation, much remains unknown regarding species-specific and <span class="hlt">seasonal</span> patterns of water uptake in a Mediterranean climate. Here, we use stable isotopes of water (d18O, dD) to define the isotope composition of water throughout the subsurface critical <span class="hlt">zone</span> of Rivendell, within the Eel River Critical <span class="hlt">Zone</span> Observatory. We find that a structured heterogeneity of water isotope composition exists in which bulk saprolite is chronically more negative than bulk soil, and tightly held moisture is more negative than the mobile water that recharges the saturated <span class="hlt">zone</span> and generates runoff. These moisture reservoirs provide a blueprint from which to measure the <span class="hlt">seasonal</span> uptake patterns of different species collocated on the site. Douglas-firs use unsaturated saprolite and weathered bedrock moisture (i. e. rock moisture) throughout the year. Contrastingly, hardwood species (madrone, live oak, tanoak) modify their source water depending on which moisture is energetically favorable. Hardwoods use freely mobile water in the wet <span class="hlt">season</span>, and rely on unsaturated <span class="hlt">zone</span> soil moisture in the dry <span class="hlt">season</span>. When soil water tension decreases on the drier south-facing slope, hardwood species use saprolite moisture. Although adjacent hardwoods and Douglas-firs partition water based on matric pull on the north side, there is competition for saprolite moisture in late summer on the south side. These results reveal the eco-hydrological importance of moisture derived from weathered bedrock, and show that the hardwoods have a competitive advantage under the drier conditions predicted in many climate models. Finally, the data emphasize that isotope measurements of all subsurface reservoirs and potential water sources are necessary for a complete and accurate characterization of the eco-hydrological processes within the critical <span class="hlt">zone</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP51A2271V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP51A2271V"><span id="translatedtitle">Little <span class="hlt">Ice</span> Age versus Present Day: Comparison of Temperature, Precipitation and <span class="hlt">Seasonality</span> in Speleothem Records from the Han-sur-Lesse Cave, Belgium.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vansteenberge, S.; Van Opdenbosch, J.; Van Rampelbergh, M.; Verheyden, S.; Keppens, E.; Cheng, H.; Edwards, R. L.; Claeys, P. F.</p> <p>2015-12-01</p> <p>The Proserpine stalagmite is a 2 m large, tabular-shaped speleothem located in the Han-sur-Lesse cave in Belgium. The speleothem formed over the last 1000 years and is still growing. High-accuracy U/Th datings have indicated exceptionally high growth-rates of up to 2 mm per year. This, together with a well expressed annual layering, makes the Proserpine stalagmite an ideal candidate for high-resolution paleoclimate reconstructions of the last millennium. Previous work, including over 10 years of cave monitoring, has already learned us how short-term, i.e. decadal to <span class="hlt">seasonal</span>, climate variations are incorporated within speleothem calcite from the Han-sur-Lesse cave system. It has been shown that δ18O and δ13C stable isotopes and trace element proxies of recently formed calcite reflect <span class="hlt">seasonal</span> variations in temperature and precipitation of the near-cave environment (Verheyden et al, 2008; Van Rampelbergh et al., 2014). Now, this knowledge was used to infer local climate parameters further back in time to the period of +/- 1620-1630 CE, corresponding to one of the cold peaks within the Little <span class="hlt">Ice</span> Age. Speleothem calcite was sampled at sub-annual resolution, with approximately 11 samples per year, for stable isotope analysis. LA-ICP-MS and µXRF analyses resulted in time series of trace elements. Preliminary results indicate a well expressed <span class="hlt">seasonal</span> signal in δ13C and trace element composition but a multi-annual to decadal trend in δ18O. This combined proxy study eventually enables comparison of the expression of <span class="hlt">seasonality</span> and longer term climate variations between a Little <span class="hlt">Ice</span> Age cold peak and Present Day. References: Verheyden, S. et al., 2008, Monitoring climatological, hydrological and geochemical parameters in the Père Noël cave (Belgium): implication for the interpretation of speleothem isotopic and geochemical time-series. International Journal of Speleology, 37(3), 221-234. Van Rampelbergh, M. et al., 2014, <span class="hlt">Seasonal</span> variations recorded in cave</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.9600N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.9600N"><span id="translatedtitle">Sub-<span class="hlt">ice</span> shelf circulation and basal melting of the Fimbul <span class="hlt">Ice</span> Shelf</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nost, Ole Anders</p> <p>2010-05-01</p> <p>The Fimbul <span class="hlt">Ice</span> Shelf is the largest of the <span class="hlt">ice</span> shelves in Dronning Maud Land. Due to a narrow and some places non-existent continental shelf, the <span class="hlt">ice</span> shelves in Dronning Maud Land are situated close to the Warm Deep Water. The Antarctic Slope Front separates the Warm Deep Water from the <span class="hlt">ice</span> shelves and complicated exchange processes working across this front controls the melting of the Fimbul <span class="hlt">Ice</span> Shelf and the other <span class="hlt">ice</span> shelves in Dronning Maud Land. Here we will present analysis of unique data from the Dronning Maud Land coastal <span class="hlt">zone</span>, as well as preliminary results from the 2009/2010 field work on the Fimbul <span class="hlt">Ice</span> Shelf. In 2008 eight elephant seals equipped with CTD data loggers collected hydrographic data in the Dronning Maud Land coastal <span class="hlt">zone</span> from February through October. Analysis of these data shows that overturning of the Antarctic Slope Front is the main process exchanging heat into the <span class="hlt">ice</span> shelf cavities. This overturning together with an onshore surface Ekman flow leads to a <span class="hlt">seasonal</span> cycle in the salinity of the coastal water masses, while glacial melting sea <span class="hlt">ice</span> formation has little influence. During the 2009/2010 field <span class="hlt">season</span> on the Fimbul <span class="hlt">Ice</span> Shelf glaciological and oceanographic data were collected. We will show preliminary results of <span class="hlt">ice</span> flow, <span class="hlt">ice</span> thickness and basal melting measured using stake nets and phase sensitive radar. Oceanographic data were collected through three hot water drilled access holes in the <span class="hlt">ice</span> shelf. These data show a water column with temperatures close to the surface freezing point over most of the water column. Relatively warmer water was observed near the bottom on one of the CTD stations. Maximum observed temperature is -1.57 °C. We compare the sub iceshelf hydrography with the hydrography observed by the elephant seals near the <span class="hlt">ice</span> front in an attempt to reveal the sub <span class="hlt">ice</span> shelf circulation. We also compare estimated melt rates from the oceanographic data with melt rates estimated with the phase sensitive radar and stake</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C11A0355C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C11A0355C"><span id="translatedtitle">Measurement and parameterization of wave attenuation and scattering in the Marginal <span class="hlt">Ice</span> <span class="hlt">Zone</span> using Sentinel-1 SAR data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Collard, F.; Ardhuin, F.; Guitton, G.; Dumont, D.; Nicot, P.; Accenti, M.; Girard-Ardhuin, F.</p> <p>2014-12-01</p> <p>Sentinel-1A launched by the European Space Agency in April 2014 will complete its full calibration and validation phase including Level2 products early in 2015 but image quality is already good enought for scientific exploitation of observed wave modulations. The larger frequency bandwidth and new acquisition modes are providing a much improved capability for imaging ocean waves in the open water and in the <span class="hlt">ice</span> compared to Envisat. Here we estimate wave spectra in the Arctic assuming a spatially uniform modulation transfer function where the backscatter over <span class="hlt">ice</span> is homogeneous, matching the wave heights in open ocean and <span class="hlt">ice</span> at the <span class="hlt">ice</span> edge. These wave properties are used to estimate attenuation scales for wavelength longer than twice the radar image resolution. These estimated attenuations are compared to model results based on WAVEWATCH III, where attenuation and scattering uses a combination of friction below the <span class="hlt">ice</span> and scattering adapted from Dumont et al. (2011) and Williams et al. (2013).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26479918','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26479918"><span id="translatedtitle"><span class="hlt">Seasonal</span> dynamics and long-term trend of hypoxia in the coastal <span class="hlt">zone</span> of Emilia Romagna (NW Adriatic Sea, Italy).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Alvisi, Francesca; Cozzi, Stefano</p> <p>2016-01-15</p> <p>Long-term series of meteorological, hydrological and oceanographic data were compared with hypoxia occurrence, in order to define characteristics and trends of this phenomenon in the Emilia Romagna Coastal <span class="hlt">Zone</span> (ERCZ) in 1977-2008. During this period, hypoxia was recorded at all sampling stations, up to 20 km offshore. In winter, spring and late autumn, hypoxia appearance was matched to significant positive anomalies of air and surface seawater temperatures (up to +3.6 °C), whereas this effect was less pronounced in August-October. Hypoxia generally occurred with scarce precipitation (0-2 dm(3)m(2)d(-1)) and low wind velocity (0-2 ms(-1)), suggesting the importance of stable meteo-marine conditions for the onset of this phenomenon. Nevertheless, wind direction emerged as an indicator of hydrodynamic <span class="hlt">seasonal</span> changes in the area and is thus a hypoxia regulator. In winter, spring and autumn, hypoxia was favored by large increases of biomass induced by river freshets. In contrast, summer hypoxia occurred during periods of low runoff, suggesting that pronounced stratification and weak circulation of coastal waters were more important in this <span class="hlt">season</span>. Since the 1990s, a shift from widespread summer hypoxia to local hypoxia irregularly distributed across the year has occurred. This process was concomitant to long-term increases of air temperature (+0.14 °C yr(-1)), wind speed (+0.03 ms(-1) yr(-1)) and salinity (+0.09 yr(-1)), and decreases of Po River flow (-0.54 km(3) yr(-1)), oxygen saturation (-0.2% yr(-1)) and PO4(3-) (-0.004 μmol P L(-1) yr(-1)) and NH4(+) (-0.04 μmol N L(-1) yr(-1)) concentrations in surface coastal waters. Despite that several of these changes suggest an ERCZ trophic level positive reduction, similar to that reported for the N Adriatic, the concomitant climate warming might further exacerbate hypoxia in particularly shallow shelf locations. Therefore, in order to avoid hypoxia development a further mitigation of anthropogenic pressure is still</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26479918','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26479918"><span id="translatedtitle"><span class="hlt">Seasonal</span> dynamics and long-term trend of hypoxia in the coastal <span class="hlt">zone</span> of Emilia Romagna (NW Adriatic Sea, Italy).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Alvisi, Francesca; Cozzi, Stefano</p> <p>2016-01-15</p> <p>Long-term series of meteorological, hydrological and oceanographic data were compared with hypoxia occurrence, in order to define characteristics and trends of this phenomenon in the Emilia Romagna Coastal <span class="hlt">Zone</span> (ERCZ) in 1977-2008. During this period, hypoxia was recorded at all sampling stations, up to 20 km offshore. In winter, spring and late autumn, hypoxia appearance was matched to significant positive anomalies of air and surface seawater temperatures (up to +3.6 °C), whereas this effect was less pronounced in August-October. Hypoxia generally occurred with scarce precipitation (0-2 dm(3)m(2)d(-1)) and low wind velocity (0-2 ms(-1)), suggesting the importance of stable meteo-marine conditions for the onset of this phenomenon. Nevertheless, wind direction emerged as an indicator of hydrodynamic <span class="hlt">seasonal</span> changes in the area and is thus a hypoxia regulator. In winter, spring and autumn, hypoxia was favored by large increases of biomass induced by river freshets. In contrast, summer hypoxia occurred during periods of low runoff, suggesting that pronounced stratification and weak circulation of coastal waters were more important in this <span class="hlt">season</span>. Since the 1990s, a shift from widespread summer hypoxia to local hypoxia irregularly distributed across the year has occurred. This process was concomitant to long-term increases of air temperature (+0.14 °C yr(-1)), wind speed (+0.03 ms(-1) yr(-1)) and salinity (+0.09 yr(-1)), and decreases of Po River flow (-0.54 km(3) yr(-1)), oxygen saturation (-0.2% yr(-1)) and PO4(3-) (-0.004 μmol P L(-1) yr(-1)) and NH4(+) (-0.04 μmol N L(-1) yr(-1)) concentrations in surface coastal waters. Despite that several of these changes suggest an ERCZ trophic level positive reduction, similar to that reported for the N Adriatic, the concomitant climate warming might further exacerbate hypoxia in particularly shallow shelf locations. Therefore, in order to avoid hypoxia development a further mitigation of anthropogenic pressure is still</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780017559','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780017559"><span id="translatedtitle">LANDSAT survey of near-shore <span class="hlt">ice</span> conditions along the Arctic coast of Alaska</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stringer, W. J. (Principal Investigator); Barrett, S. A.</p> <p>1978-01-01</p> <p>The author has identified the following significant results. Winter and spring near-shore <span class="hlt">ice</span> conditions were analyzed for the Beaufort Sea 1973-77, and the Chukchi Sea 1973-76. LANDSAT imagery was utilized to map major <span class="hlt">ice</span> features related to regional <span class="hlt">ice</span> morphology. Significant features from individual LANDSAT image maps were combined to yield regional maps of major <span class="hlt">ice</span> ridge systems for each year of study and maps of flaw lead systems for representative <span class="hlt">seasons</span> during each year. These regional maps were, in turn, used to prepare <span class="hlt">seasonal</span> <span class="hlt">ice</span> morphology maps. These maps showed, in terms of a zonal analysis, regions of statistically uniform <span class="hlt">ice</span> behavior. The behavioral characteristics of each <span class="hlt">zone</span> were described in terms of coastal processes and bathymetric configuration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DSRII.131..170W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DSRII.131..170W"><span id="translatedtitle">Zooplankton abundance and biomass size spectra in the East Antarctic sea-<span class="hlt">ice</span> <span class="hlt">zone</span> during the winter-spring transition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wallis, Jake R.; Swadling, Kerrie M.; Everett, Jason D.; Suthers, Iain M.; Jones, Hugh J.; Buchanan, Pearse J.; Crawford, Christine M.; James, Lainey C.; Johnson, Robert; Meiners, Klaus M.; Virtue, Patti; Westwood, Karen; Kawaguchi, So</p> <p>2016-09-01</p> <p>Sea <span class="hlt">ice</span> is an influential feature in Southern Ocean-Antarctic marine environments creating a 2-phase vertical ecosystem. The lack of information on how this system influences community structure during the winter-spring transition, however, is largely lacking. Zooplankton form the link that bridges these environments, with the meiofaunal and algal communities within sea <span class="hlt">ice</span> directly influencing the epipelagic zooplankton community at the <span class="hlt">ice</span>-water interface. A combination of methods including sea-<span class="hlt">ice</span> coring, umbrella net sampling and Laser Optical Plankton Counter were used to describe the vertical structure of zooplankton and meiofaunal communities. The distribution of meiofauna and chlorophyll a both played important roles in structuring the zooplankton community within this dynamic region. Many dominant taxa, including Calanus propinquus and Oithona similis, directly responded to the high availability of algae present within the bottom strata of sea <span class="hlt">ice</span>. The sea-<span class="hlt">ice</span> associated species Stephos longipes represented a strong link between this 2-phase ecosystem. Observations of the vertical distribution of biomass obtained from the LOPC suggests that the responses of these species to the sea <span class="hlt">ice</span> directly influences the vertical structure of zooplankton during the winter-spring transition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015ChJOL..33..222L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015ChJOL..33..222L&link_type=ABSTRACT"><span id="translatedtitle">CO2 flux and <span class="hlt">seasonal</span> variability in the turbidity maximum <span class="hlt">zone</span> and surrounding area in the Changjiang River estuary</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Xuegang; Song, Jinming; Yuan, Huamao; Li, Ning; Duan, Liqin; Qu, Baoxiao</p> <p>2015-01-01</p> <p>The turbidity maximum <span class="hlt">zone</span> (TMZ) is one of the most important regions in an estuary. However, the high concentration of suspended material makes it difficult to measure the partial pressure of CO2 ( pCO2) in these regions. Therefore, very little data is available on the pCO2 levels in TMZs. To relatively accurately evaluate the CO2 flux in an example estuary, we studied the TMZ and surrounding area in the Changjiang (Yangtze) River estuary. From <span class="hlt">seasonal</span> cruises during February, August, November 2010, and May 2012, the pCO2 in the TMZ and surrounding area was calculated from pH and total alkalinity (TA) measured in situ, from which the CO2 flux was calculated. Overall, the TMZ and surrounding area acted as a source of atmosphere CO2 in February and November, and as a sink in May and August. The average FCO2 was -9, -16, 5, and 5 mmol/(m2·d) in May, August, November, and February, respectively. The TMZ's role as a source or sink of atmosphere CO2 was quite different to the outer estuary. In the TMZ and surrounding area, suspended matter, phytoplankton, and pH were the main factors controlling the FCO2, but here the influence of temperature, salinity, and total alkalinity on the FCO2 was weak. Organic carbon decomposition in suspended matter was the main reason for the region acting as a CO2 source in winter, and phytoplankton production was the main reason the region was a CO2 sink in summer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19016339','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19016339"><span id="translatedtitle">Effects of <span class="hlt">season</span> and agro-ecological <span class="hlt">zone</span> on the microbial quality of raw milk along the various levels of the value chain in Uganda.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grimaud, Patrice; Sserunjogi, Mohamed; Wesuta, Milton; Grillet, Nelly; Kato, Moses; Faye, Bernard</p> <p>2009-08-01</p> <p>Dairy production in Uganda is pasture-based and traditional Ankole cattle make up 80% of the cattle herd, reared in both pastoral and agro-pastoral ecological <span class="hlt">zones</span>. Regardless of the <span class="hlt">zone</span>, milk quality is lowest in production basin during the dry <span class="hlt">season</span> when ambient temperatures are highest and water is scarce. Poor hygiene and quality management contributed to the deterioration of raw milk quality during its storage and delivery to the final consumer, and concealed the <span class="hlt">seasonal</span> effect when milk reached urban consumption areas. Poor milk quality is a challenge for the Ugandan Dairy Development Authorities who wish to make the milk value chain safe. This study provides baseline information for the implementation of an HACCP-based system to ensure the hygienic quality of milk from the farm to the market place.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C51A0674L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C51A0674L"><span id="translatedtitle">Investigating the Biases in the Antarctic Sea <span class="hlt">Ice</span> - Ocean System of Climate Models using Process-oriented Diagnostics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lecomte, O.; Goosse, H.; Fichefet, T.; Holland, P.; Uotila, P.; Zunz, V.</p> <p>2015-12-01</p> <p>Most analyses of Antarctic sea <span class="hlt">ice</span> in simulations of the CMIP5 archive have so far been oriented towards the quantification of the disagreement between model results and sea <span class="hlt">ice</span> observations only. Since the decomposition of those biases into distinct physical components is necessary to understand their origins, we propose here an ocean-sea <span class="hlt">ice</span>-atmosphere integrated and process-oriented approach. Not only the biases in variables essential to the sea <span class="hlt">ice</span> <span class="hlt">seasonal</span> evolution are estimated regionally with regard to observations, but their contributions to the sea <span class="hlt">ice</span> concentration budget are estimated. Following a previously developed method, the sea <span class="hlt">ice</span> concentration balance over the autumn-winter <span class="hlt">seasons</span> is decomposed into four terms, including the sea <span class="hlt">ice</span> concentration change during the period of interest, advection, divergence and a residual accounting for the net contribution of thermodynamics and <span class="hlt">ice</span> deformation. Concurrently, correlations between trends in ocean temperature at depth and trends in <span class="hlt">ice</span> concentration are calculated directly from various model output fields (including CMIP5 models) to disentangle the role of <span class="hlt">ice</span>-ocean interactions. Results show that the geographical patterns of all mean sea <span class="hlt">ice</span> concentration budget terms over 1992-2005 are in qualitative agreement with the observed ones. Sea <span class="hlt">ice</span> thermodynamic growth is maintained by horizontal divergence near the continent and in the central <span class="hlt">ice</span> pack, whereas melting close to the <span class="hlt">ice</span> edge is led by sea <span class="hlt">ice</span> advection. However, significant errors in all budget terms are observed due to <span class="hlt">ice</span> velocities that tend to be overestimated all around Antarctica in several models, leading to a relatively weak divergence in the inner <span class="hlt">ice</span> pack and to an excessive advection in the marginal <span class="hlt">ice</span> <span class="hlt">zone</span>. Biases in <span class="hlt">ice</span> drift speed and direction are ultimately related to biases in winds in all models. This method paves the way for a systematic assessment of forthcoming CMIP6 sea <span class="hlt">ice</span> model outputs in the Southern Hemisphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12712582','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12712582"><span id="translatedtitle">[Dynamics of ecological-biochemical characteristics of the sea <span class="hlt">ice</span> in the coastal <span class="hlt">zone</span> of the White sea].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mel'nikov, I A; Korneeva, G A; zhitina, L S; Shanin, S S</p> <p>2003-01-01</p> <p>The distribution of salinity, silicon and phosphorus contents, and hydrolytic enzyme activities along a sea-coast transect was studied in melted <span class="hlt">ice</span> cores and water samples taken from under the <span class="hlt">ice</span> cover in the periods of active <span class="hlt">ice</span> formation and melting in the Kandalaksha Bay, White Sea. The species list of identified algae was compiled, which included 170 species and varieties (90% of them belonged to diatoms). Strong correlations were revealed between the salinity of water samples and the content of silicon, protease activity, and the species composition of algae. Preliminary estimations of the rate of photosynthetic processes in individual cells of algae belonging to the mass species of the <span class="hlt">ice</span> flora are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012LPI....43.1169P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012LPI....43.1169P"><span id="translatedtitle">Evidence of Complex <span class="hlt">Ice</span>-Volcano Interactions in the Transition <span class="hlt">Zone</span> Between Elysium Rise and Utopia Basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pedersen, G. B. M.; Head, J. W.</p> <p>2012-03-01</p> <p>We report on morphologic evidence of a complex succession of <span class="hlt">ice</span>-volcano interactions in the Galaxias region, Mars, and reconsider the emplacement properties of volcanoclastic outflow deposit under martian conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRD..121.1043W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRD..121.1043W"><span id="translatedtitle">Atmospheric conditions in the central Arctic Ocean through the melt <span class="hlt">seasons</span> of 2012 and 2013: Impact on surface conditions and solar energy deposition into the <span class="hlt">ice</span>-ocean system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Caixin; Granskog, Mats A.; Hudson, Stephen R.; Gerland, Sebastian; Pavlov, Alexey K.; Perovich, Donald K.; Nicolaus, Marcel</p> <p>2016-02-01</p> <p>Spectral Radiation Buoys and <span class="hlt">ice</span> mass balance buoys were deployed on first-year <span class="hlt">ice</span> near the North Pole in April 2012 and 2013, collecting in-band (350-800 nm) solar radiation and <span class="hlt">ice</span> and snow mass balance data over the complete summer melt <span class="hlt">seasons</span>. With complementary European ERA-Interim reanalysis, National Centers for Environmental Prediction (NCEP) Climate forecast system version 2 (CFSv2) analysis and satellite passive microwave data, we examine the evolution of atmospheric and surface melt conditions in the two differing melt <span class="hlt">seasons</span>. Prevailing atmospheric conditions contributed to a longer and more continuous melt <span class="hlt">season</span> in summer 2012 than in 2013, which was corroborated by in situ observations. ERA-Interim reanalysis data showed that longwave radiation likely played a key role in delaying the snowmelt onset in 2013. The earlier melt onset in 2012 reduced the albedo, providing a positive <span class="hlt">ice</span>-albedo feedback at a time when solar insolation was high. Due to earlier melt onset and later freeze-up in 2012, more solar heat was deposited into the <span class="hlt">ice</span>-ocean system than in 2013. Summer 2013 was characterized by later melt onset, intermittent freezing events and an earlier fall freeze-up, resulting in considerably fewer effective days of surface melt and a higher average albedo. Calculations for idealized <span class="hlt">seasonal</span> albedo evolution show that moving the melt onset just 1 week earlier in mid-June increases the total absorbed solar radiation by nearly 14% for the summer <span class="hlt">season</span>. Therefore, the earlier melt onset may have been one of the most important factors driving the more dramatic melt <span class="hlt">season</span> in 2012 than 2013, though atmospheric circulation patterns, e.g., cyclone in early August 2012, likely contributed as well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C21A0726Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C21A0726Y"><span id="translatedtitle"><span class="hlt">Ice</span> Sheet Meltwater Impacts on Biological Productivity in High-Latitude Coastal <span class="hlt">Zones</span> - Observations and Model Results for West Antarctica and Southwest Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yager, P. L.; Oliver, H.; Sherrell, R. M.; Stammerjohn, S. E.; St-Laurent, P.; Hofmann, E. E.; Mote, T. L.; Castelao, R. M.; Rennermalm, A. K.; Tedesco, M.; Arrigo, K. R.</p> <p>2015-12-01</p> <p>Surface mass balance observations and models confirm that both the west Antarctic and Greenland <span class="hlt">Ice</span> Sheets have undergone accelerating <span class="hlt">ice</span> mass losses during the past decade. These losses enhance freshwater discharge to the ocean and have important implications for ocean circulation and sea level, but they can also impact marine ecosystems and carbon cycling. High-latitude primary productivity is limited by light or nutrients (or both), and phytoplankton access to these limiting factors can be altered by freshwater additions. Mechanisms for delivering meltwater to the ocean are complex and depend in part on whether the melt occurs at the <span class="hlt">ice</span>-atmosphere or <span class="hlt">ice</span>-ocean interface. Marine-terminus glaciers may generate buoyant plumes at depth, similar to upwelling whereas runoff from glacial termini on land will behave more like a riverine point source at the ocean surface. Here, we present preliminary results from two ongoing efforts to understand these impacts: one from the Amundsen Sea Polynya (ASP) in west Antarctica (NSF-funded INSPIRE), and another from NASA-IDS <span class="hlt">Ice</span> Sheet Impact Study in coastal Greenland. Field observations from the Amundsen Sea Polynya International Research Expedition (ASPIRE) showed how the enormous phytoplankton bloom in the central ASP depends on an iron supply from the Dotson <span class="hlt">Ice</span> Shelf (DIS). This outcome implied a three-dimensional pathway for iron, from the DIS cavity to the euphotic <span class="hlt">zone</span> of the ASP bloom region located 20-100 km offshore. Such a pathway differs from the traditional one-dimensional view, where nutrients are injected into the euphotic <span class="hlt">zone</span> by vertical mixing. Mesoscale structures and eddies may play a central role. A ROMS model is used to investigate key physical and biogeochemical processes in the ASP region. A similar effort is underway to investigate the fate of extreme melt from Greenland and its impact on primary productivity. In coastal Greenland, meltwater is modeled as surface runoff and the resulting shallower</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19054540','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19054540"><span id="translatedtitle">Comparison of glacial and non-glacial-fed streams to evaluate the loading of persistent organic pollutants through <span class="hlt">seasonal</span> snow/<span class="hlt">ice</span> melt.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bizzotto, E C; Villa, S; Vaj, C; Vighi, M</p> <p>2009-02-01</p> <p>The release of persistent organic pollutants (PCBs, HCB, HCHs and DDTs) accumulated in Alpine glaciers, was studied during spring-summer 2006 on the Frodolfo glacial-fed stream (Italian Alps). Samples were also taken on a non-glacial stream in the same valley, to compare POP contribution from different water sources (glacier <span class="hlt">ice</span>, recent snow and spring). In late spring and early summer (May, June) recent snow melting is the most important process. POP contamination is more affected by local emissions and transport, and comparable levels have been measured in both streams for all studied compounds. In late summer and autumn (July-October), the contribution of <span class="hlt">ice</span> melting strongly increases. In the glacial-fed stream the concentration of chlorinated pesticides (HCHs and DDTs) is about one order of magnitude higher than in the non-glacial-fed. A different behaviour was observed for PCBs, characterised by a peak in June showing, in both streams, concentrations three orders of magnitude higher than the background levels measured in May and in October. This result should be attributed to local emissions rather than long range atmospheric transport (LRAT). This hypothesis is supported by the PCB congener profile in June strictly comparable to the most commonly used Aroclor technical mixtures. The different <span class="hlt">seasonal</span> behaviour observed for the different groups of chemicals indicates the POP loading in glacial streams is a combined role of long range atmospheric transport and local emission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4803742','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4803742"><span id="translatedtitle">Root <span class="hlt">Zone</span> Cooling and Exogenous Spermidine Root-Pretreatment Promoting Lactuca sativa L. Growth and Photosynthesis in the High-temperature <span class="hlt">Season</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sun, Jin; Lu, Na; Xu, Hongjia; Maruo, Toru; Guo, Shirong</p> <p>2016-01-01</p> <p>Root <span class="hlt">zone</span> high-temperature stress is a major factor limiting hydroponic plant growth during the high-temperature <span class="hlt">season</span>. The effects of root <span class="hlt">zone</span> cooling (RZC; at 25°C) and exogenous spermidine (Spd) root-pretreatment (SRP, 0.1 mM) on growth, leaf photosynthetic traits, and chlorophyll fluorescence characteristics of hydroponic Lactuca sativa L. grown in a high-temperature <span class="hlt">season</span> (average temperature > 30°C) were examined. Both treatments significantly promoted plant growth and photosynthesis in the high-temperature <span class="hlt">season</span>, but the mechanisms of photosynthesis improvement in the hydroponic grown lettuce plants were different between the RZC and SRP treatments. The former improved plant photosynthesis by increasing stoma conductance (Gs) to enhance CO2 supply, thus promoting photosynthetic electron transport activity and phosphorylation, which improved the level of the photochemical efficiency of photosystem II (PSII), rather than enhancing CO2 assimilation efficiency. The latter improved plant photosynthesis by enhancing CO2 assimilation efficiency, rather than stomatal regulation. Combination of RZC and SRP significantly improved PN of lettuce plants in a high-temperature <span class="hlt">season</span> by both improvement of Gs to enhance CO2 supply and enhancement of CO2 assimilation. The enhancement of photosynthetic efficiency in both treatments was independent of altering light-harvesting or excessive energy dissipation. PMID:27047532</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27047532','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27047532"><span id="translatedtitle">Root <span class="hlt">Zone</span> Cooling and Exogenous Spermidine Root-Pretreatment Promoting Lactuca sativa L. Growth and Photosynthesis in the High-temperature <span class="hlt">Season</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sun, Jin; Lu, Na; Xu, Hongjia; Maruo, Toru; Guo, Shirong</p> <p>2016-01-01</p> <p>Root <span class="hlt">zone</span> high-temperature stress is a major factor limiting hydroponic plant growth during the high-temperature <span class="hlt">season</span>. The effects of root <span class="hlt">zone</span> cooling (RZC; at 25°C) and exogenous spermidine (Spd) root-pretreatment (SRP, 0.1 mM) on growth, leaf photosynthetic traits, and chlorophyll fluorescence characteristics of hydroponic Lactuca sativa L. grown in a high-temperature <span class="hlt">season</span> (average temperature > 30°C) were examined. Both treatments significantly promoted plant growth and photosynthesis in the high-temperature <span class="hlt">season</span>, but the mechanisms of photosynthesis improvement in the hydroponic grown lettuce plants were different between the RZC and SRP treatments. The former improved plant photosynthesis by increasing stoma conductance (G s) to enhance CO2 supply, thus promoting photosynthetic electron transport activity and phosphorylation, which improved the level of the photochemical efficiency of photosystem II (PSII), rather than enhancing CO2 assimilation efficiency. The latter improved plant photosynthesis by enhancing CO2 assimilation efficiency, rather than stomatal regulation. Combination of RZC and SRP significantly improved P N of lettuce plants in a high-temperature <span class="hlt">season</span> by both improvement of G s to enhance CO2 supply and enhancement of CO2 assimilation. The enhancement of photosynthetic efficiency in both treatments was independent of altering light-harvesting or excessive energy dissipation. PMID:27047532</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT.......110D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT.......110D"><span id="translatedtitle">Alaska shorefast <span class="hlt">ice</span>: Interfacing geophysics with local sea <span class="hlt">ice</span> knowledge and use</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Druckenmiller, Matthew L.</p> <p></p