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Sample records for sea ice snow

  1. MODIS Snow and Sea Ice Products

    NASA Technical Reports Server (NTRS)

    Hall, Dorothy K.; Riggs, George A.; Salomonson, Vincent V.

    2004-01-01

    In this chapter, we describe the suite of Earth Observing System (EOS) Moderate-Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua snow and sea ice products. Global, daily products, developed at Goddard Space Flight Center, are archived and distributed through the National Snow and Ice Data Center at various resolutions and on different grids useful for different communities Snow products include binary snow cover, snow albedo, and in the near future, fraction of snow in a 5OO-m pixel. Sea ice products include ice extent determined with two different algorithms, and sea ice surface temperature. The algorithms used to develop these products are described. Both the snow and sea ice products, available since February 24,2000, are useful for modelers. Validation of the products is also discussed.

  2. Microwave remote sensing of snow-covered sea ice

    NASA Technical Reports Server (NTRS)

    Borgeaud, M.; Kong, J. A.; Lin, F. C.

    1986-01-01

    Snow and ice are modeled as random media characterized by different dielectric constants and correlation functions. In order to model the brine inclusions of sea ice, the random medium is assumed to be anisotropic. A three-layer model is used to simulate a snow-covered ice field with the top layer being snow, the middle layer being ice, and the bottom layer being sea water. The theoretical results are illustrated for thick first-year sea ice covered by dry snow, and for artificial, thin first-year sea ice covered by wet snow as measured in controlled model tank experiments. The radar backscattering cross sections are seen to increase with snow cover for snow-covered sea ice owing to large volume scattering effects of snow.

  3. Interdecadal Changes in Snow Depth on Arctic Sea Ice

    NASA Technical Reports Server (NTRS)

    Webster, Melinda A.; Rigor, Ignatius G.; Nghiem, Son V.; Kurtz, Nathan T.; Farrell, Sinead L.; Perovich, Donald K.; Sturm, Matthew

    2014-01-01

    Snow plays a key role in the growth and decay of Arctic sea ice. In winter, it insulates sea ice from cold air temperatures, slowing sea ice growth. From spring to summer, the albedo of snow determines how much insolation is absorbed by the sea ice and underlying ocean, impacting ice melt processes. Knowledge of the contemporary snow depth distribution is essential for estimating sea ice thickness and volume, and for understanding and modeling sea ice thermodynamics in the changing Arctic. This study assesses spring snow depth distribution on Arctic sea ice using airborne radar observations from Operation IceBridge for 2009-2013. Data were validated using coordinated in situ measurements taken in March 2012 during the Bromine, Ozone, and Mercury Experiment (BROMEX) field campaign. We find a correlation of 0.59 and root-mean-square error of 5.8 cm between the airborne and in situ data. Using this relationship and Ice- Bridge snow thickness products, we compared the recent results with data from the 1937, 1954-1991 Soviet drifting ice stations. The comparison shows thinning of the snowpack, from 35.169.4 to 22.261.9 cm in the western Arctic, and from 32.869.4 to 14.561.9 cm in the Beaufort and Chukchi seas. These changes suggest a snow depth decline of 37629% in the western Arctic and 56633% in the Beaufort and Chukchi seas. Thinning is negatively correlated with the delayed onset of sea ice freezeup during autumn.

  4. Simulating Snow Over Sea Ice In Climate Models

    NASA Technical Reports Server (NTRS)

    Arnold, James E. (Technical Monitor); Marshall, Susan; Oglesby, Robert J.; Drobot, Sheldon; Anderson, Mark

    2002-01-01

    We have evaluated two methods of simulating the seasonal cycle of snow over sea ice in and around the Arctic: The NCAR global climate model CCM3, with its standard snow hydrology, and the snow pack model SNTHERM, forced with hourly atmospheric output from CCM3. A new dataset providing dates for the onset of snow melt over Arctic sea ice provides a means for assessing basin-wide how well the models simulate melt onset, but contains no information on how long it then takes for all the snow to melt. Use of data from the SHEBA site provides very detailed information on the behavior of the snow before and during the melt season, but only for a very limited area. Russian drift data provide climatological data on the seasonal cycle of snow water equivalent and snow density, over multi-year sea ice in the central Arctic basin. These datasets are used to compare the two modeling methods, and to see if use of the more physically-realistic SNTHERM provides any significant improvements. Conclusions obtained so far include: 1. Both CCM3 and CCM3/SNTHERM do a good job overall of matching the onset of snow melt dataset; although CCM3/SNTHERM consistently trends to underestimate the date and CCM3 to overestimate it. 2. SHEBA and ice drift data for the Arctic show that CCM3/ SNTHERM does a better job than CCM3 at simulating the total melt period. 3. Ice drift snow density and accumulation data suggest that while providing superior results, CCM3/SNTHERM may still suffer from overly vigorous melting. 4. Both the large-scale atmospheric forcing and snow pack physical processes are important in proper simulation of the snow seasonal cycle. Ongoing work includes further diagnosis of CCM3/SNTHERM, use of more observational datasets, especially from marginal seas in the pan-Arctic, and full coupling of SNTHERM into CCM3 (work to date has all been off-line simulations).

  5. Airborne Surveys of Snow Depth over Arctic Sea Ice

    NASA Technical Reports Server (NTRS)

    Kwok, R.; Panzer, B.; Leuschen, C.; Pang, S.; Markus, T.; Holt, B.; Gogineni, S.

    2011-01-01

    During the spring of 2009, an ultrawideband microwave radar was deployed as part of Operation IceBridge to provide the first cross-basin surveys of snow thickness over Arctic sea ice. In this paper, we analyze data from three approx 2000 km transects to examine detection issues, the limitations of the current instrument, and the regional variability of the retrieved snow depth. Snow depth is the vertical distance between the air \\snow and snow-ice interfaces detected in the radar echograms. Under ideal conditions, the per echogram uncertainty in snow depth retrieval is approx 4 - 5 cm. The finite range resolution of the radar (approx 5 cm) and the relative amplitude of backscatter from the two interfaces limit the direct retrieval of snow depths much below approx 8 cm. Well-defined interfaces are observed over only relatively smooth surfaces within the radar footprint of approx 6.5 m. Sampling is thus restricted to undeformed, level ice. In early April, mean snow depths are 28.5 +/- 16.6 cm and 41.0 +/- 22.2 cm over first-year and multiyear sea ice (MYI), respectively. Regionally, snow thickness is thinner and quite uniform over the large expanse of seasonal ice in the Beaufort Sea, and gets progressively thicker toward the MYI cover north of Ellesmere Island, Greenland, and the Fram Strait. Snow depth over MYI is comparable to that reported in the climatology by Warren et al. Ongoing improvements to the radar system and the utility of these snow depth measurements are discussed.

  6. The Effects of Snow Depth Forcing on Southern Ocean Sea Ice Simulations

    NASA Technical Reports Server (NTRS)

    Powel, Dylan C.; Markus, Thorsten; Stoessel, Achim

    2003-01-01

    The spatial and temporal distribution of snow on sea ice is an important factor for sea ice and climate models. First, it acts as an efficient insulator between the ocean and the atmosphere, and second, snow is a source of fresh water for altering the already weak Southern Ocean stratification. For the Antarctic, where the ice thickness is relatively thin, snow can impact the ice thickness in two ways: a) As mentioned above snow on sea ice reduces the ocean-atmosphere heat flux and thus reduces freezing at the base of the ice flows; b) a heavy snow load can suppress the ice below sea level which causes flooding and, with subsequent freezing, a thickening of the sea ice (snow-to-ice conversion). In this paper, we compare different snow fall paramterizations (incl. the incorporation of satellite-derived snow depth) and study the effect on the sea ice using a sea ice model.

  7. Large-Scale Surveys of Snow Depth on Arctic Sea Ice from Operation IceBridge

    NASA Technical Reports Server (NTRS)

    Kurtz, Nathan T.; Farrell, Sinead L.

    2011-01-01

    We show the first results of a large ]scale survey of snow depth on Arctic sea ice from NASA fs Operation IceBridge snow radar system for the 2009 season and compare the data to climatological snow depth values established over the 1954.1991 time period. For multiyear ice, the mean radar derived snow depth is 33.1 cm and the corresponding mean climatological snow depth is 33.4 cm. The small mean difference suggests consistency between contemporary estimates of snow depth with the historical climatology for the multiyear ice region of the Arctic. A 16.5 cm mean difference (climatology minus radar) is observed for first year ice areas suggesting that the increasingly seasonal sea ice cover of the Arctic Ocean has led to an overall loss of snow as the region has transitioned away from a dominantly multiyear ice cover.

  8. Airborne radar surveys of snow depth over Antarctic sea ice during Operation IceBridge

    NASA Astrophysics Data System (ADS)

    Panzer, B.; Gomez-Garcia, D.; Leuschen, C.; Paden, J. D.; Gogineni, P. S.

    2012-12-01

    Over the last decade, multiple satellite-based laser and radar altimeters, optimized for polar observations, have been launched with one of the major objectives being the determination of global sea ice thickness and distribution [5, 6]. Estimation of sea-ice thickness from these altimeters relies on freeboard measurements and the presence of snow cover on sea ice affects this estimate. Current means of estimating the snow depth rely on daily precipitation products and/or data from passive microwave sensors [2, 7]. Even a small uncertainty in the snow depth leads to a large uncertainty in the sea-ice thickness estimate. To improve the accuracy of the sea-ice thickness estimates and provide validation for measurements from satellite-based sensors, the Center for Remote Sensing of Ice Sheets deploys the Snow Radar as a part of NASA Operation IceBridge. The Snow Radar is an ultra-wideband, frequency-modulated, continuous-wave radar capable of resolving snow depth on sea ice from 5 cm to more than 2 meters from long-range, airborne platforms [4]. This paper will discuss the algorithm used to directly extract snow depth estimates exclusively using the Snow Radar data set by tracking both the air-snow and snow-ice interfaces. Prior work in this regard used data from a laser altimeter for tracking the air-snow interface or worked under the assumption that the return from the snow-ice interface was greater than that from the air-snow interface due to a larger dielectric contrast, which is not true for thick or higher loss snow cover [1, 3]. This paper will also present snow depth estimates from Snow Radar data during the NASA Operation IceBridge 2010-2011 Antarctic campaigns. In 2010, three sea ice flights were flown, two in the Weddell Sea and one in the Amundsen and Bellingshausen Seas. All three flight lines were repeated in 2011, allowing an annual comparison of snow depth. In 2011, a repeat pass of an earlier flight in the Weddell Sea was flown, allowing for a comparison of snow depths with two weeks elapsed between passes. [1] Farrell, S.L., et al., "A First Assessment of IceBridge Snow and Ice Thickness Data Over Arctic Sea Ice," IEEE Tran. Geoscience and Remote Sensing, Vol. 50, No. 6, pp. 2098-2111, June 2012. [2] Kwok, R., and G. F. Cunningham, "ICESat over Arctic sea ice: Estimation of snow depth and ice thickness," J. Geophys. Res., 113, C08010, 2008. [3] Kwok, R., et al., "Airborne surveys of snow depth over Arctic sea ice," J. Geophys. Res., 116, C11018, 2011. [4] Panzer, B., et al., "An ultra-wideband, microwave radar for measuring snow thickness on sea ice and mapping near-surface internal layers in polar firn," Submitted to J. Glaciology, July 23, 2012. [5] Wingham, D.J., et al., "CryoSat: A Mission to Determine the Fluctuations in Earth's Land and Marine Ice Fields," Advances in Space Research, Vol. 37, No. 4, pp. 841-871, 2006. [6] Zwally, H. J., et al., "ICESat's laser measurements of polar ice, atmosphere, ocean, and land," J. Geodynamics, Vol. 34, No. 3-4, pp. 405-445, Oct-Nov 2002. [7] Zwally, H. J., et al., "ICESat measurements of sea ice freeboard and estimates of sea ice thickness in the Weddell Sea," J. Geophys. Res., 113, C02S15, 2008.

  9. Sensitivity of simulated Arctic sea ice to realistic ice thickness distributions and snow parameterizations

    NASA Astrophysics Data System (ADS)

    Castro-Morales, K.; Kauker, F.; Losch, M.; Hendricks, S.; Riemann-Campe, K.; Gerdes, R.

    2014-01-01

    Sea ice and snow on sea ice to a large extent determine the surface heat budget in the Arctic Ocean. In spite of the advances in modeling sea-ice thermodynamics, a good number of models still rely on simple parameterizations of the thermodynamics of ice and snow. Based on simulations with an Arctic sea-ice model coupled to an ocean general circulation model, we analyzed the impact of changing two sea-ice parameterizations: (1) the prescribed ice thickness distribution (ITD) for surface heat budget calculations, and (2) the description of the snow layer. For the former, we prescribed a realistic ITD derived from airborne electromagnetic induction sounding measurements. For the latter, two different types of parameterizations were tested: (1) snow thickness independent of the sea-ice thickness below, and (2) a distribution proportional to the prescribed ITD. Our results show that changing the ITD from seven uniform categories to fifteen nonuniform categories derived from field measurements, and distributing the snow layer according to the ITD, leads to an increase in average Arctic-wide ice thickness by 0.56 m and an increase by 1 m in the Canadian Arctic Archipelago and Canadian Basin. This increase is found to be a direct consequence of 524 km3 extra thermodynamic growth during the months of ice formation (January, February, and March). Our results emphasize that these parameterizations are a key factor in sea-ice modeling to improve the representation of the sea-ice energy balance.

  10. Assessment of radar-derived snow depth over Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Newman, Thomas; Farrell, Sinead L.; Richter-Menge, Jacqueline; Connor, Laurence N.; Kurtz, Nathan T.; Elder, Bruce C.; McAdoo, David

    2014-12-01

    Knowledge of contemporaneous snow depth on Arctic sea ice is important both to constrain the regional climatology and to improve the accuracy of satellite altimeter estimates of sea ice thickness. We assess new data available from the NASA Operation IceBridge snow radar instrument and derive snow depth estimates across the western Arctic ice pack using a novel methodology based on wavelet techniques that define the primary reflecting surfaces within the snow pack. We assign uncertainty to the snow depth estimates based upon both the radar system parameters and sea ice topographic variability. The accuracy of the airborne snow depth estimates are examined via comparison with coincident measurements gathered in situ across a range of ice types in the Beaufort Sea. We discuss the effect of surface morphology on the derivation, and consequently the accuracy, of airborne snow depth estimates. We find that snow depths derived from the airborne snow radar using the wavelet-based technique are accurate to 1 cm over level ice. Over rougher surfaces including multiyear and ridged ice, the radar system is impacted by ice surface morphology. Across basin scales, we find the snow-radar-derived snow depth on first-year ice is at least ˜60% of the value reported in the snow climatology for the Beaufort Sea, Canada Basin, and parts of the central Arctic, since these regions were previously dominated by multiyear ice during the measurement period of the climatology. Snow on multiyear ice is more consistent with the climatology.

  11. Effects of subgrid-scale snow thickness variability on radiative transfer in sea ice

    NASA Astrophysics Data System (ADS)

    Abraham, Carsten; Steiner, Nadja; Monahan, Adam; Michel, Christine

    2015-08-01

    Snow is a principal factor in controlling heat and light fluxes through sea ice. With the goal of improving radiative and heat flux estimates through sea ice in regional and global models without the need of detailed snow property descriptions, a new parameterization including subgrid-scale snow thickness variability is presented. One-parameter snow thickness distributions depending only on the gridbox-mean snow thickness are introduced resulting in analytical solutions for the fluxes of heat and light through the snow layer. As the snowpack melts, these snow thickness distributions ensure a smooth seasonal transition of the light field under sea ice. Spatially homogenous melting applied to an inhomogeneous distribution of snow thicknesses allows the appearance of bare sea ice areas and melt ponds before all snow has melted. In comparison to uniform-thickness snow used in previous models, the bias in the under sea-ice light field is halved with this parameterization. Model results from a one-dimensional ocean turbulence model coupled with a thermodynamic sea ice model are compared to observations near Resolute in the Canadian High Arctic. The simulations show substantial improvements not only to the light field at the sea ice base which will affect ice algal growth but also to the sea ice and seasonal snowpack evolution. During melting periods, the snowpack can survive longer while sea ice thickness starts to reduce earlier.

  12. Sea Ice Thickness, Freeboard, and Snow Depth products from Operation IceBridge Airborne Data

    NASA Technical Reports Server (NTRS)

    Kurtz, N. T.; Farrell, S. L.; Studinger, M.; Galin, N.; Harbeck, J. P.; Lindsay, R.; Onana, V. D.; Panzer, B.; Sonntag, J. G.

    2013-01-01

    The study of sea ice using airborne remote sensing platforms provides unique capabilities to measure a wide variety of sea ice properties. These measurements are useful for a variety of topics including model evaluation and improvement, assessment of satellite retrievals, and incorporation into climate data records for analysis of interannual variability and long-term trends in sea ice properties. In this paper we describe methods for the retrieval of sea ice thickness, freeboard, and snow depth using data from a multisensor suite of instruments on NASA's Operation IceBridge airborne campaign. We assess the consistency of the results through comparison with independent data sets that demonstrate that the IceBridge products are capable of providing a reliable record of snow depth and sea ice thickness. We explore the impact of inter-campaign instrument changes and associated algorithm adaptations as well as the applicability of the adapted algorithms to the ongoing IceBridge mission. The uncertainties associated with the retrieval methods are determined and placed in the context of their impact on the retrieved sea ice thickness. Lastly, we present results for the 2009 and 2010 IceBridge campaigns, which are currently available in product form via the National Snow and Ice Data Center

  13. Contaminants in arctic snow collected over northwest Alaskan sea ice

    USGS Publications Warehouse

    Garbarino, J.R.; Snyder-Conn, E.; Leiker, T.J.; Hoffman, G.L.

    2002-01-01

    Snow cores were collected over sea ice from four northwest Alaskan Arctic estuaries that represented the annual snowfall from the 1995-1996 season. Dissolved trace metals, major cations and anions, total mercury, and organochlorine compounds were determined and compared to concentrations in previous arctic studies. Traces (<4 nanograms per liter, ng L-1) of cis- and trans-chlordane, dimethyl 2,3,5,6-tetrachloroterephthalate, dieldrin, endosulfan II, and PCBs were detected in some samples, with endosulfan I consistently present. High chlorpyrifos concentrations (70-80 ng L-1) also were estimated at three sites. The snow was highly enriched in sulfates (69- 394 mg L-1), with high proportions of nonsea salt sulfates at three of five sites (9 of 15 samples), thus indicating possible contamination through long-distance transport and deposition of sulfate-rich atmospheric aerosols. Mercury, cadmium, chromium, molybdenum, and uranium were typically higher in the marine snow (n = 15) in relation to snow from arctic terrestrial studies, whereas cations associated with terrigenous sources, such as aluminum, frequently were lower over the sea ice. One Kasegaluk Lagoon site (Chukchi Sea) had especially high concentrations of total mercury (mean = 214 ng L-1, standard deviation = 5 ng L-1), but no methyl mercury was detected above the method detection limit (0.036 ng L-1) at any of the sites. Elevated concentrations of sulfate, mercury, and certain heavy metals might indicate mechanisms of contaminant loss from the arctic atmosphere over marine water not previously reported over land areas. Scavenging by snow, fog, or riming processes and the high content of deposited halides might facilitate the loss of such contaminants from the atmosphere. Both the mercury and chlorpyrifos concentrations merit further investigation in view of their toxicity to aquatic organisms at low concentrations.

  14. Improving Surface Mass Balance Over Ice Sheets and Snow Depth on Sea Ice

    NASA Technical Reports Server (NTRS)

    Koenig, Lora Suzanne; Box, Jason; Kurtz, Nathan

    2013-01-01

    Surface mass balance (SMB) over ice sheets and snow on sea ice (SOSI) are important components of the cryosphere. Large knowledge gaps remain in scientists' abilities to monitor SMB and SOSI, including insufficient measurements and difficulties with satellite retrievals. On ice sheets, snow accumulation is the sole mass gain to SMB, and meltwater runoff can be the dominant single loss factor in extremely warm years such as 2012. SOSI affects the growth and melt cycle of the Earth's polar sea ice cover. The summer of 2012 saw the largest satellite-recorded melt area over the Greenland ice sheet and the smallest satellite-recorded Arctic sea ice extent, making this meeting both timely and relevant.

  15. Interannual and Regional Variability of Southern Ocean Snow on Sea Ice and its Correspondence with Sea Ice Cover and Atmospheric Circulation Patterns

    NASA Technical Reports Server (NTRS)

    Markus, T.; Cavalieri, D. J.

    2006-01-01

    Snow depth on sea ice plays a critical role in the heat exchange between ocean and atmosphere because of its thermal insulation property. Furthermore, a heavy snow load on the relatively thin Southern Ocean sea-ice cover submerges the ice floes below sea level, causing snow-to-ice conversion. Snowfall is also an important freshwater source into the weakly stratified ocean. Snow depth on sea-ice information can be used as an indirect measure of solid precipitation. Satellite passive microwave data are used to investigate the interannual and regional variability of the snow cover on sea ice. In this study we make use of 12 years (1992-2003) of Special Sensor Microwave/Imager (SSM/I) radiances to calculate average monthly snow depth on the Antarctic sea-ice cover. The results show a slight increase in snow depth and a partial eastward propagation of maximum snow depths, which may be related to the Antarctic Circumpolar Wave.

  16. Snow depth on Arctic sea ice derived from radar: In situ comparisons and time series analysis

    NASA Astrophysics Data System (ADS)

    Holt, Benjamin; Johnson, Michael P.; Perkovic-Martin, Dragana; Panzer, Ben

    2015-06-01

    The snow radar being flown on NASA's Operation IceBridge, ongoing aircraft campaigns to the Arctic and the Antarctic are providing unique observations of the depth of snow on the sea ice cover. In this paper, we focus on the radar-derived snow depth results from the 2009-2012 Arctic campaigns. We develop and evaluate the use of a distinct snow layer tracker to measure snow depth based on a Support Vector Machine (SVM) supervised learning algorithm. The snow radar is designed to detect both the air-snow and snow-ice interfaces using ultrawideband frequencies from 2 to 8 GHz. The quality, errors, and repeatability of the snow radar snow depth estimates are examined, based on comparisons with in situ data obtained during two separate sea ice field campaigns, the GreenArc 2009 and the CryoVEx 2011 campaigns off Greenland in the Lincoln Sea. Finally, we analyze 4 years (2009-2012) of three annually repeated sea ice flight lines obtained in early spring, located off Greenland and the Canadian Arctic. We examine the annual variations of snow depth differences between perennial and seasonal ice when available. Overall, the snow layer tracker produced consistent, accurate results for snow depths between 0.10 and ˜0.60 m. This was confirmed with comparisons with the two data sets from the in situ measurement campaigns as well as with the time series analysis, and is consistent with other published results.

  17. The impact of snow depth, snow density and ice density on sea ice thickness retrieval from satellite radar altimetry: results from the ESA-CCI Sea Ice ECV Project Round Robin Exercise

    NASA Astrophysics Data System (ADS)

    Kern, S.; Khvorostovsky, K.; Skourup, H.; Rinne, E.; Parsakhoo, Z. S.; Djepa, V.; Wadhams, P.; Sandven, S.

    2015-01-01

    We assess different methods and input parameters, namely snow depth, snow density and ice density, used in freeboard-to-thickness conversion of Arctic sea ice. This conversion is an important part of sea ice thickness retrieval from spaceborne altimetry. A data base is created comprising sea ice freeboard derived from satellite radar altimetry between 1993 and 2012 and co-locate observations of total (sea ice + snow) and sea ice freeboard from the Operation Ice Bridge (OIB) and CryoSat Validation Experiment (CryoVEx) airborne campaigns, of sea ice draft from moored and submarine upward looking sonar (ULS), and of snow depth from OIB campaigns, Advanced Microwave Scanning Radiometer (AMSR-E) and the Warren climatology (Warren et al., 1999). We compare the different data sets in spatiotemporal scales where satellite radar altimetry yields meaningful results. An inter-comparison of the snow depth data sets emphasizes the limited usefulness of Warren climatology snow depth for freeboard-to-thickness conversion under current Arctic Ocean conditions reported in other studies. We test different freeboard-to-thickness and freeboard-to-draft conversion approaches. The mean observed ULS sea ice draft agrees with the mean sea ice draft derived from radar altimetry within the uncertainty bounds of the data sets involved. However, none of the approaches are able to reproduce the seasonal cycle in sea ice draft observed by moored ULS. A sensitivity analysis of the freeboard-to-thickness conversion suggests that sea ice density is as important as snow depth.

  18. Advances in Airborne Altimetric Techniques for the Measurement of Snow on Arctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Newman, T.; Farrell, S. L.; Richter-Menge, J.; Elder, B. C.; Ruth, J.; Connor, L. N.

    2014-12-01

    Current sea ice observations and models indicate a transition towards a more seasonal Arctic ice pack with a smaller, and geographically more variable, multiyear ice component. To gain a comprehensive understanding of the processes governing this transition it is important to include the impact of the snow cover, determining the mechanisms by which snow is both responding to and forcing changes to the sea ice pack. Data from NASA's Operation IceBridge (OIB) snow radar system, which has been making yearly surveys of the western Arctic since 2009, offers a key resource for investigating the snow cover. In this work, we characterize the OIB snow radar instrument response to ascertain the location of 'side-lobes', aiding the interpretation of snow radar data. We apply novel wavelet-based techniques to identify the primary reflecting interfaces within the snow pack from which snow depth estimates are derived. We apply these techniques to the range of available snow radar data collected over the last 6 years during the NASA OIB mission. Our results are validated through comparison with a range of in-situ data. We discuss the impact of sea ice surface morphology on snow radar returns (with respect to ice type) and the topographic conditions over which accurate snow-radar-derived snow depths may be obtained. Finally we present improvements to in situ survey design that will allow for both an improved sampling of the snow radar footprint and more accurate assessment of the uncertainties in radar-derived snow depths in the future.

  19. Snow Depth and Ice Thickness Measurements From the Beaufort and Chukchi Seas Collected During the AMSR-Ice03 Campaign

    NASA Technical Reports Server (NTRS)

    Sturm, M.; Holmgren, J.; Maslanik, J. A.; Perovich, D. K.; Richter-Menge, J.; Stroeve, J. C.; Markus, T.; Heinrichs, J. F.; Tape, K.

    2006-01-01

    In March 2003, a field validation campaign was conducted on the sea ice near Barrow, AK. The goal of this campaign was to produce an extensive dataset of sea ice thickness and snow properties (depth and stratigraphy) against which remote sensing products collected by aircraft and satellite could be compared. Chief among these were products from the Polarimetric Scanning Radiometer (PSR) flown aboard a NASA P-3B aircraft and the Aqua Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E). The data were collected in four field areas: three on the coastal sea ice near Barrow, AK, and the fourth out on the open ice pack 175 km northeast of Barrow. The snow depth ranged from 9.4-20.8 cm in coastal areas (n = 9881 for three areas) with the thinnest snow on ice that had formed late in the winter. Out in the main pack ice, the snow was 20.6 cm deep (n = 1906). The ice in all four areas ranged from 138-219 cm thick (n = 1952), with the lower value again where the ice had formed late in the winter. Snow layer and grain characteristics observed in 118 snow pits indicated that 44% of observed snow layers were depth hoar; 46% were wind slab. Snow and ice measurements were keyed to photomosaics produced from low-altitude vertical aerial photographs. Using these, and a distinctive three-way relationship between ice roughness, snow surface characteristics, and snow depth, strip maps of snow depth, each about 2 km wide, were produced bracketing the traverse lines. These maps contain an unprecedented level of snow depth detail against which to compare remote sensing products. The maps are used in other papers in this special issue to examine the retrieval of snow properties from the PSR and AMSR-E sensors.

  20. Snow on Arctic sea ice: model representation and last decade changes

    NASA Astrophysics Data System (ADS)

    Castro-Morales, K.; Ricker, R.; Gerdes, R.

    2015-10-01

    Together with sea ice, Arctic snow has experienced vast changes during the last decade due to a warming climate. Thus, it is relevant to study the past and present changes of Arctic snow to understand the implications to the sea ice component, precipitation, heat and radiation budgets. In this study, we analyze the changes of snow depth between 2000 and 2013 at regional scale represented in an Arctic coupled sea ice-general circulation model. We evaluate the model performance by direct comparison of the modeled snow depths (hs_mod) to snow depths from radar measurements from the NASA Operation IceBridge (hs_OIB) during the flight campaigns completed from 2009 to 2013. Despite the description of the snow in our model is simple (i.e. single layer without explicit snow redistribution processes) as in many current sea-ice models; the latitudinal distribution of hs_mod in the western Arctic is in good agreement to observations. The hs_mod is on average 3 cm thicker than hs_OIB in latitudes > 76° N. According to the model results, the hs in 2013 decreased 21 % with respect to the multi-year mean between 2000 and 2013. This snow reduction occurred mainly in FYI dominated areas, and is in good agreement to the year-to-year loss of sea ice, also well reproduced by the model. In a simple snow mass budget, our results show that 65 % of the yearly accumulated snow is lost by sublimation and snowmelt due to the heat transfer between the snow/ice interface and the atmosphere. Although the snow layer accumulates again every year, the long-term reduction in the summer sea-ice extent ultimately affects the maximum spring accumulation of snow. The model results exhibit a last decade thinning of the snowpack that is however one order of magnitude lower than previous estimates based on radar measurements. We suggest that the later is partially due to the lack of explicit snow redistribution processes in the model, emphasizing the need to include these in current sea-ice models to improve the snow representations.

  1. Validation of Airborne FMCW Radar Measurements of Snow Thickness Over Sea Ice in Antarctica

    NASA Technical Reports Server (NTRS)

    Galin, Natalia; Worby, Anthony; Markus, Thorsten; Leuschen, Carl; Gogineni, Prasad

    2012-01-01

    Antarctic sea ice and its snow cover are integral components of the global climate system, yet many aspects of their vertical dimensions are poorly understood, making their representation in global climate models poor. Remote sensing is the key to monitoring the dynamic nature of sea ice and its snow cover. Reliable and accurate snow thickness data are currently a highly sought after data product. Remotely sensed snow thickness measurements can provide an indication of precipitation levels, predicted to increase with effects of climate change in the polar regions. Airborne techniques provide a means for regional-scale estimation of snow depth and distribution. Accurate regional-scale snow thickness data will also facilitate an increase in the accuracy of sea ice thickness retrieval from satellite altimeter freeboard estimates. The airborne data sets are easier to validate with in situ measurements and are better suited to validating satellite algorithms when compared with in situ techniques. This is primarily due to two factors: better chance of getting coincident in situ and airborne data sets and the tractability of comparison between an in situ data set and the airborne data set averaged over the footprint of the antennas. A 28-GHz frequency modulated continuous wave (FMCW) radar loaned by the Center for Remote Sensing of Ice Sheets to the Australian Antarctic Division is used to measure snow thickness over sea ice in East Antarctica. Provided with the radar design parameters, the expected performance parameters of the radar are summarized. The necessary conditions for unambiguous identification of the airsnow and snowice layers for the radar are presented. Roughnesses of the snow and ice surfaces are found to be dominant determinants in the effectiveness of layer identification for this radar. Finally, this paper presents the first in situ validated snow thickness estimates over sea ice in Antarctica derived from an FMCW radar on a helicopterborne platform.

  2. Snow Dunes: A Controlling Factor of Melt Pond Distribution on Arctic Sea Ice

    NASA Technical Reports Server (NTRS)

    Petrich, Chris; Eicken, Hajo; Polashenski, Christopher M.; Sturm, Matthew; Harbeck, Jeremy P.; Perovich, Donald K.; Finnegan, David C.

    2012-01-01

    The location of snow dunes over the course of the ice-growth season 2007/08 was mapped on level landfast first-year sea ice near Barrow, Alaska. Landfast ice formed in mid-December and exhibited essentially homogeneous snow depths of 4-6 cm in mid-January; by early February distinct snow dunes were observed. Despite additional snowfall and wind redistribution throughout the season, the location of the dunes was fixed by March, and these locations were highly correlated with the distribution of meltwater ponds at the beginning of June. Our observations, including ground-based light detection and ranging system (lidar) measurements, show that melt ponds initially form in the interstices between snow dunes, and that the outline of the melt ponds is controlled by snow depth contours. The resulting preferential surface ablation of ponded ice creates the surface topography that later determines the melt pond evolution.

  3. Chemical Atmosphere-Snow-Sea Ice Interactions: defining future research in the field, lab and modeling

    NASA Astrophysics Data System (ADS)

    Frey, Markus

    2015-04-01

    The air-snow-sea ice system plays an important role in the global cycling of nitrogen, halogens, trace metals or carbon, including greenhouse gases (e.g. CO2 air-sea flux), and therefore influences also climate. Its impact on atmospheric composition is illustrated for example by dramatic ozone and mercury depletion events which occur within or close to the sea ice zone (SIZ) mostly during polar spring and are catalysed by halogens released from SIZ ice, snow or aerosol. Recent field campaigns in the high Arctic (e.g. BROMEX, OASIS) and Antarctic (Weddell sea cruises) highlight the importance of snow on sea ice as a chemical reservoir and reactor, even during polar night. However, many processes, participating chemical species and their interactions are still poorly understood and/or lack any representation in current models. Furthermore, recent lab studies provide a lot of detail on the chemical environment and processes but need to be integrated much better to improve our understanding of a rapidly changing natural environment. During a 3-day workshop held in Cambridge/UK in October 2013 more than 60 scientists from 15 countries who work on the physics, chemistry or biology of the atmosphere-snow-sea ice system discussed research status and challenges, which need to be addressed in the near future. In this presentation I will give a summary of the main research questions identified during this workshop as well as ways forward to answer them through a community-based interdisciplinary approach.

  4. A Coordinated Ice-based and Airborne Snow and Ice Thickness Measurement Campaign on Arctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Richter-Menge, J.; Farrell, S.; Elder, B. C.; Gardner, J. M.; Brozena, J. M.

    2011-12-01

    A rare opportunity presented itself in March 2011 when the Naval Research Laboratory (NRL) and NASA IceBridge teamed with scientists from the U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory (CRREL) to coordinate a multi-scale approach to mapping snow depth and sea ice thickness distribution in the Arctic. Ground-truth information for calibration/validation of airborne and CryoSat-2 satellite data were collected near a manned camp deployed in support of the US Navy's Ice Expedition 2011 (ICEX 2011). The ice camp was established at a location approximately 230 km north of Prudhoe Bay, Alaska, at the edge of the perennial ice zone. The suite of measurements was strategically organized around a 9-km-long survey line that covered a wide range of ice types, including refrozen leads, deformed and undeformed first year ice, and multiyear ice. A highly concentrated set of in situ measurements of snow depth and ice thickness were taken along the survey line. Once the survey line was in place, NASA IceBridge flew a dedicated mission along the survey line, collecting data with an instrument suite that included the Airborne Topographic Mapper (ATM), a high precision, airborne scanning laser altimeter; the Digital Mapping System (DMS), nadir-viewing digital camera; and the University of Kansas ultra-wideband Frequency Modulated Continuous Wave (FMCW) snow radar. NRL also flew a dedicated mission over the survey line with complementary airborne radar, laser and photogrammetric sensors (see Brozena et al., this session). These measurements were further leveraged by a series of CryoSat-2 under flights made in the region by the instrumented NRL and NASA planes, as well as US Navy submarine underpasses of the 9-km-long survey line to collect ice draft measurements. This comprehensive suite of data provides the full spectrum of sampling resolutions from satellite, to airborne, to ground-based, to submarine and will allow for a careful determination of snow depth on sea ice and characterization of the regional sea ice thickness distribution. This poster will present preliminary data from the measurement campaign. This includes the in situ measurements of snow depth and ice thickness along the survey line. The NASA IceBridge airborne survey consisted of eleven parallel flight lines along the main in situ transect and two perpendicular passes at the northern and southern ends of the survey line, coincident with two corner reflectors. We will present initial IceBridge data, including ATM sea ice elevation and DMS photography which we use to estimate surface roughness and delineate sea ice provinces nearby the in situ survey. Preliminary data from the NRL over flights of the survey line will be presented in the poster by Brozena et al. (this session). The in situ and airborne data collected during the March 2011 campaign will be fully-documented and archived on the NASA IceBridge websites at NSIDC, allowing for their free access by the broad research community.

  5. 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.

  6. Estimation of Sea Ice Thickness Distributions through the Combination of Snow Depth and Satellite Laser Altimetry Data

    NASA Technical Reports Server (NTRS)

    Kurtz, Nathan T.; Markus, Thorsten; Cavalieri, Donald J.; Sparling, Lynn C.; Krabill, William B.; Gasiewski, Albin J.; Sonntag, John G.

    2009-01-01

    Combinations of sea ice freeboard and snow depth measurements from satellite data have the potential to provide a means to derive global sea ice thickness values. However, large differences in spatial coverage and resolution between the measurements lead to uncertainties when combining the data. High resolution airborne laser altimeter retrievals of snow-ice freeboard and passive microwave retrievals of snow depth taken in March 2006 provide insight into the spatial variability of these quantities as well as optimal methods for combining high resolution satellite altimeter measurements with low resolution snow depth data. The aircraft measurements show a relationship between freeboard and snow depth for thin ice allowing the development of a method for estimating sea ice thickness from satellite laser altimetry data at their full spatial resolution. This method is used to estimate snow and ice thicknesses for the Arctic basin through the combination of freeboard data from ICESat, snow depth data over first-year ice from AMSR-E, and snow depth over multiyear ice from climatological data. Due to the non-linear dependence of heat flux on ice thickness, the impact on heat flux calculations when maintaining the full resolution of the ICESat data for ice thickness estimates is explored for typical winter conditions. Calculations of the basin-wide mean heat flux and ice growth rate using snow and ice thickness values at the 70 m spatial resolution of ICESat are found to be approximately one-third higher than those calculated from 25 km mean ice thickness values.

  7. The Role of Blowing Snow in the Activation of Bromine over First-Year Antarctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Lieb-Lappen, R.; Obbard, R. W.

    2014-12-01

    It is well known that during the polar springtime, halide sea salt ions, in particular Br-, are through a series of heterogeneous reactions photochemically activated into reactive halogen species, such as Br and BrO, that breakdown polar tropospheric ozone. This research investigated the role of blowing snow in transporting salts from the sea ice/snow surface into reactive bromine species in the air. For two different locations over first-year ice in the Ross Sea, Antarctica, collection baskets captured blowing snow at four different heights on October 25, following a blowing snow event the day before. In addition, sea ice cores and surface snow samples were collected throughout the month long campaign. Cl-/Br- ratios were constant in sea ice and surface snow, and only in lofted snow did bromide become depleted relative to chloride. This suggests that replenishment of bromide in the snowpack occurs faster than bromine activation in mid-strength wind conditions (approximately 10 m/s). Sulfate concentrations were stable through the bottom half of sea ice cores, but were quite variable in the upper half and in surface snow. Lofted snow was greatly depleted in sulfate, likely as a result of mirabilite precipitation in brine prior to brine uptake in the snow and subsequent lofting. Nitrate was found in greater quantities for upper level baskets and in some surface snow samples, consistent with active cycling through atmospheric chemical reactions.

  8. The impact of atmospheric mineral aerosol deposition on the albedo of snow and sea ice: are snow and sea ice optical properties more important than mineral aerosol optical properties?

    NASA Astrophysics Data System (ADS)

    Lamare, M. L.; Lee-Taylor, J.; King, M. D.

    2015-08-01

    Knowledge of the albedo of polar regions is crucial for understanding a range of climatic processes that have an impact on a global scale. Light absorbing impurities in atmospheric aerosols deposited on snow and sea ice by aeolian transport absorb solar radiation, reducing albedo. Here, the effects of five mineral aerosol deposits reducing the albedo of polar snow and sea ice are considered. Calculations employing a coupled atmospheric and snow/sea ice radiative-transfer model (TUV-snow) show that the effects of mineral aerosol deposits is strongly dependent on the snow or sea ice type rather than the differences between the aerosol optical characteristics. The change in albedo between five different mineral aerosol deposits with refractive indices varying by a factor of 2 reaches a maximum of 0.0788, whereas the difference between cold polar snow and melting sea ice is 0.8893 for the same mineral loading. Surprisingly, the thickness of a surface layer of snow or sea ice loaded with the same mass-ratio of mineral dust has little effect on albedo. On the contrary, multiple layers of mineral aerosols deposited during episodic events evenly distributed play a similar role in the surface albedo of snow as a loading distributed throughout, even when the layers are further apart. The impact of mineral aerosol deposits is much larger on melting sea ice than on other types of snow and sea ice. Therefore, the higher input of shortwave radiation during the summer melt cycle associated with melting sea ice accelerates the melt process.

  9. Comparison of a coupled snow thermodynamic and radiative transfer model with in-situ active microwave signatures of snow-covered smooth first-year sea ice

    NASA Astrophysics Data System (ADS)

    Fuller, M. C.; Geldsetzer, T.; Yackel, J.; Gill, J. P. S.

    2015-06-01

    Within the context of developing data inversion and assimilation techniques for C-band backscatter over sea ice, snow physical models may be used to drive backscatter models for comparison and optimization with satellite observations. Such modeling has potential to enhance understanding of snow on sea ice properties required for unambiguous interpretation of active microwave imagery. An end-to-end modeling suite is introduced, incorporating regional reanalysis data (NARR), a snow model (SNTHERM), and a multi-layer snow and ice active microwave backscatter model (MSIB). This modeling suite is assessed against measured snow on sea ice geophysical properties, and against measured active microwave backscatter. NARR data was input to the SNTHERM snow thermodynamic model, in order to drive the MISB model for comparison to detailed geophysical measurements and surface-based observations of C-band backscatter of snow on first-year sea ice. The NARR data was well correlated to available in-situ measurements, with the exception of long wave incoming radiation and relative humidity, which impacted SNTHERM simulations of snow temperature. SNTHERM reasonably represented snow grain size and density when compared to observations. The application of in-situ salinity profiles to one SNTHERM snow profile resulted in simulated backscatter close to that driven by in-situ snow properties. In other test cases, the simulated backscatter remained 4 to 6 dB below observed for higher incidence angles, and when compared to an average simulated backscatter of in-situ end-member snowcovers. Development of C-band inversion and assimilation schemes employing SNTHERM89.rev4 should consider sensitivity of the model to bias in incoming longwave radiation, the effects of brine, and the inability of SNTHERM89.Rev4 to simulate water accumulation and refreezing at the bottom and mid-layers of the snowpack with regard to thermodynamic response, brine wicking and volume processes, snow dielectrics, and microwave backscatter from snow on first-year sea-ice.

  10. Modelling changes in the dielectric and scattering properties of young snow-covered sea ice at GHz frequencies

    NASA Technical Reports Server (NTRS)

    Drinkwater, Mark R.; Crocker, G. B.

    1988-01-01

    Observations of the physical properties of the snow cover and underlying young fast ice in Resolute Passage, Canada, were made during the winter of 1982. Detailed measurements of snow density and ice and snow temperatures, salinities, and brine volumes were made over a period of 46 d, beginning when the ice was 0.4 m thick and about 9 d old. The recorded values are used in a theoretical mixture model to predict the dielectric properties of the snow cover over the microwave frequency range. The results of this analysis are then used to investigate the effects of the snow properties on the radar backscatter signatures of young sea ice. The results show that backscatter is a function of the incidence angle and can change significantly over short periods of time during the early evolutionary phase of ice and snow-cover development. This has important consequences for the identification of young ice forms from SAR or SLAR images.

  11. SNOW ON ANTARCTIC SEA ICE Robert A. Massom,1

    E-print Network

    Warren, Stephen

    coefficient [Andreas et al., 1993] and the bulk transfer coefficients for latent and sensible heat [Andreas size, density, and salinity; frequency of occurrence of slush; thermal conductivity, snow surface; lower observed values of snow thermal conductivity than those typically used in models; periodic large

  12. The role of blowing snow in the activation of bromine over first-year Antarctic sea ice

    NASA Astrophysics Data System (ADS)

    Lieb-Lappen, R. M.; Obbard, R. W.

    2015-07-01

    It is well known that during polar springtime halide sea salt ions, in particular Br-, are photochemically activated into reactive halogen species (e.g., Br and BrO), where they break down tropospheric ozone. This research investigated the role of blowing snow in transporting salts from the sea ice/snow surface into reactive bromine species in the air. At two different locations over first-year ice in the Ross Sea, Antarctica, collection baskets captured blowing snow at different heights. In addition, sea ice cores and surface snow samples were collected throughout the month-long campaign. Over this time, sea ice and surface snow Br- / Cl- mass ratios remained constant and equivalent to seawater, and only in lofted snow did bromide become depleted relative to chloride. This suggests that replenishment of bromide in the snowpack occurs faster than bromine activation in mid-strength wind conditions (approximately 10 m s-1) or that blowing snow represents only a small portion of the surface snowpack. Additionally, lofted snow was found to be depleted in sulfate and enriched in nitrate relative to surface snow.

  13. Examining the ability of snow and sea ice to maintain halogen activation

    NASA Astrophysics Data System (ADS)

    Simpson, W. R.; Walsh, S. J.; Peterson, P. K.; Gleason, E.; Shepson, P.; Pratt, K. A.; Halfacre, J. W.; Oltmans, S. J.; Domine, F.; Nghiem, S. V.; Perovich, D. K.; Sturm, M.

    2012-12-01

    During Arctic springtime, photochemistry converts sea salts to reactive halogens (e.g. bromine atoms and bromine monoxide) that then drastically change the oxidation chemistry of the overlying atmosphere. These halogen activation events are widespread and ubiquitous across the Arctic Basin, particularly on the sea ice and nearby, affecting ozone, mercury, and organic oxidation processes. Heterogeneous chemistry that recycles reservoirs of halogens (e.g. HBr or sea salt Br-) to reactive halogens appears necessary to create a "bromine explosion" and maintain halogen activation. In this study, we examine the end-of-season transition between the period of halogen activation in springtime to the period during which activation ceases in summer. This transition is very abrupt in nearly all records of Arctic BrO, including campaigns at Barrow, Alaska, and on the sea ice as observed by O-Buoys. In this work, we examine the environmental conditions that change at the day that halogen chemistry is no longer supported. It appears that atmospherically accessible ice surface area, afforded by "dry" snow, is critical to maintain halogen activation, and surface melting, even without much loss of snowpack, terminates this chemistry. A variety of snow properties, including microwave signatures (sensitive to snow wetness), near infrared albedo changes, and temperature are investigated to get more insight into both the underlying chemical mechanism and how one might be able to use remote sensing to determine areas where halogen activation can/cannot occur.

  14. Recent Increases in Snow Accumulation and Decreases in Sea-Ice Concentration Recorded in a Coastal NW Greenland Ice Core

    NASA Astrophysics Data System (ADS)

    Osterberg, E. C.; Thompson, J. T.; Wong, G. J.; Hawley, R. L.; Kelly, M. A.; Lutz, E.; Howley, J.; Ferris, D. G.

    2013-12-01

    A significant rise in summer temperatures over the past several decades has led to widespread retreat of the Greenland Ice Sheet (GIS) margin and surrounding sea ice. Recent observations from geodetic stations and GRACE show that ice mass loss progressed from South Greenland up to Northwest Greenland by 2005 (Khan et al., 2010). Observations from meteorological stations at the U.S. Thule Air Force Base, remote sensing platforms, and climate reanalyses indicate a 3.5C mean annual warming in the Thule region and a 44% decrease in summer (JJAS) sea-ice concentrations in Baffin Bay from 1980-2010. Mean annual precipitation near Thule increased by 12% over this interval, with the majority of the increase occurring in fall (SON). To improve projections of future ice loss and sea-level rise in a warming climate, we are currently developing multi-proxy records (lake sediment cores, ice cores, glacial geologic data, glaciological models) of Holocene climate variability and cryospheric response in NW Greenland, with a focus on past warm periods. As part of our efforts to develop a millennial-length ice core paleoclimate record from the Thule region, we collected and analyzed snow pit samples and short firn cores (up to 20 m) from the coastal region of the GIS (2Barrel site; 76.9317 N, 63.1467 W) and the summit of North Ice Cap (76.938 N, 67.671 W) in 2011 and 2012, respectively. The 2Barrel ice core was sampled using a continuous ice core melting system at Dartmouth, and subsequently analyzed for major anion and trace element concentrations and stable water isotope ratios. Here we show that the 2Barrel ice core spanning 1990-2010 records a 25% increase in mean annual snow accumulation, and is positively correlated (r = 0.52, p<0.01) with ERA-Interim precipitation. The 2Barrel annual sea-salt Na concentration is strongly correlated (r = 0.5-0.8, p<0.05) with summer and fall sea-ice concentrations in northern Baffin Bay near Thule (Figure 1). We hypothesize that the positive correlation represents a significant Na contribution from frost flowers growing on fall frazil ice. Ongoing analyses will evaluate the relationship between MSA concentrations and sea ice extent. Our results show that a deep ice core collected from this dynamic and climate-sensitive region of NW Greenland would produce a valuable record of late Holocene climate and sea ice extent.

  15. Freeboard, Snow Depth and Sea-Ice Roughness in East Antarctica from In Situ and Multiple Satellite Data

    NASA Technical Reports Server (NTRS)

    Markus, Thorsten; Masson, Robert; Worby, Anthony; Lytle, Victoria; Kurtz, Nathan; Maksym, Ted

    2011-01-01

    In October 2003 a campaign on board the Australian icebreaker Aurora Australis had the objective to validate standard Aqua Advanced Microwave Scanning Radiometer (AMSR-E) sea-ice products. Additionally, the satellite laser altimeter on the Ice, Cloud and land Elevation Satellite (ICESat) was in operation. To capture the large-scale information on the sea-ice conditions necessary for satellite validation, the measurement strategy was to obtain large-scale sea-ice statistics using extensive sea-ice measurements in a Lagrangian approach. A drifting buoy array, spanning initially 50 km 100 km, was surveyed during the campaign. In situ measurements consisted of 12 transects, 50 500 m, with detailed snow and ice measurements as well as random snow depth sampling of floes within the buoy array using helicopters. In order to increase the amount of coincident in situ and satellite data an approach has been developed to extrapolate measurements in time and in space. Assuming no change in snow depth and freeboard occurred during the period of the campaign on the floes surveyed, we use buoy ice-drift information as well as daily estimates of thin-ice fraction and rough-ice vs smooth-ice fractions from AMSR-E and QuikSCAT, respectively, to estimate kilometer-scale snow depth and freeboard for other days. The results show that ICESat freeboard estimates have a mean difference of 1.8 cm when compared with the in situ data and a correlation coefficient of 0.6. Furthermore, incorporating ICESat roughness information into the AMSR-E snow depth algorithm significantly improves snow depth retrievals. Snow depth retrievals using a combination of AMSR-E and ICESat data agree with in situ data with a mean difference of 2.3 cm and a correlation coefficient of 0.84 with a negligible bias.

  16. Comparison of a coupled snow thermodynamic and radiative transfer model with in situ active microwave signatures of snow-covered smooth first-year sea ice

    NASA Astrophysics Data System (ADS)

    Fuller, M. C.; Geldsetzer, T.; Yackel, J.; Gill, J. P. S.

    2015-11-01

    Within the context of developing data inversion and assimilation techniques for C-band backscatter over sea ice, snow physical models may be used to drive backscatter models for comparison and optimization with satellite observations. Such modeling has the potential to enhance understanding of snow on sea-ice properties required for unambiguous interpretation of active microwave imagery. An end-to-end modeling suite is introduced, incorporating regional reanalysis data (NARR), a snow model (SNTHERM89.rev4), and a multilayer snow and ice active microwave backscatter model (MSIB). This modeling suite is assessed against measured snow on sea-ice geophysical properties and against measured active microwave backscatter. NARR data were input to the SNTHERM snow thermodynamic model in order to drive the MSIB model for comparison to detailed geophysical measurements and surface-based observations of C-band backscatter of snow on first-year sea ice. The NARR variables were correlated to available in situ measurements with the exception of long-wave incoming radiation and relative humidity, which impacted SNTHERM simulations of snow temperature. SNTHERM snow grain size and density were comparable to observations. The first assessment of the forward assimilation technique developed in this work required the application of in situ salinity profiles to one SNTHERM snow profile, which resulted in simulated backscatter close to that driven by in situ snow properties. In other test cases, the simulated backscatter remained 4-6 dB below observed for higher incidence angles and when compared to an average simulated backscatter of in situ end-member snow covers. Development of C-band inversion and assimilation schemes employing SNTHERM89.rev4 should consider sensitivity of the model to bias in incoming long-wave radiation, the effects of brine, and the inability of SNTHERM89.Rev4 to simulate water accumulation and refreezing at the bottom and mid-layers of the snowpack. These impact thermodynamic response, brine wicking and volume processes, snow dielectrics, and thus microwave backscatter from snow on first-year sea ice.

  17. An ultra-wideband, microwave radar for measuring snow thickness on sea ice and mapping near-surface internal layers in polar firn

    E-print Network

    Panzer, Ben; Gomez-Garcia, Daniel; Leuschen, Carl; Paden, John D.; Rodriguez-Morales, Fernando; Patel, Aqsa; Markus, Thorsten; Holt, Benjamin; Gogineni, Sivaprasad

    2013-04-01

    Sea ice is generally covered with snow, which can vary in thickness from a few centimeters to >1 m. Snow cover acts as a thermal insulator modulating the heat exchange between the ocean and the atmosphere, and it impacts ...

  18. (abstract) A Polarimetric Model for Effects of Brine Infiltrated Snow Cover and Frost Flowers on Sea Ice Backscatter

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.

    1995-01-01

    A polarimetric scattering model is developed to study effects of snow cover and frost flowers with brine infiltration on thin sea ice. Leads containing thin sea ice in the Artic icepack are important to heat exchange with the atmosphere and salt flux into the upper ocean. Surface characteristics of thin sea ice in leads are dominated by the formation of frost flowers with high salinity. In many cases, the thin sea ice layer is covered by snow, which wicks up brine from sea ice due to capillary force. Snow and frost flowers have a significant impact on polarimetric signatures of thin ice, which needs to be studied for accessing the retrieval of geophysical parameters such as ice thickness. Frost flowers or snow layer is modeled with a heterogeneous mixture consisting of randomly oriented ellipsoids and brine infiltration in an air background. Ice crystals are characterized with three different axial lengths to depict the nonspherical shape. Under the covering multispecies medium, the columinar sea-ice layer is an inhomogeneous anisotropic medium composed of ellipsoidal brine inclusions preferentially oriented in the vertical direction in an ice background. The underlying medium is homogeneous sea water. This configuration is described with layered inhomogeneous media containing multiple species of scatterers. The species are allowed to have different size, shape, and permittivity. The strong permittivity fluctuation theory is extended to account for the multispecies in the derivation of effective permittivities with distributions of scatterer orientations characterized by Eulerian rotation angles. Polarimetric backscattering coefficients are obtained consistently with the same physical description used in the effective permittivity calculation. The mulitspecies model allows the inclusion of high-permittivity species to study effects of brine infiltrated snow cover and frost flowers on thin ice. The results suggest that the frost cover with a rough interface significantly increases the backscatter from thin saline ice and the polarimetric signature becomes closer to the isotropic characteristics. The snow cover also modifies polarimetric signatures of thin sea ice depending on the snow mixture and the interface condition.

  19. Bacterial and extracellular polysaccharide content of brine-wetted snow over Arctic winter first-year sea ice

    NASA Astrophysics Data System (ADS)

    Ewert, M.; Carpenter, S. D.; Colangelo-Lillis, J.; Deming, J. W.

    2013-02-01

    During freeze-up and consolidation, sea ice rejects to its surface brine of marine origin that is incorporated into overlying snow. To evaluate the transport of biological components in brines from ice to snow, vertical profiles of temperature, salinity, bacterial abundance, and extracellular polysaccharide substances (EPS) were obtained through snow and first-year sea ice (Barrow, AK) in consecutive winters (2010, 2011). Snow profiles showed strong interannual variation, with 2010 presenting higher values and wider ranges in salinity (0.3-30.9, practical salinity), bacterial abundance (2.8 × 102-1.5 × 104 cells mL- 1), and particulate EPS (pEPS, 0.04-0.23 glucose equivalents (glu-eq) mg L- 1) than 2011 (0-11.9, 2.7 × 103-4.2 × 103 cells mL- 1 and 0.04-0.09 glu-eq mg L- 1, respectively). Surface ice also differed interannually, with 2010 presenting again higher salinity (19.4, n = 1), bacterial abundance (5.4 × 104-9.6 × 104 cells mL- 1) and pEPS (0.13-0.51 glu-eq mg L- 1) than 2011 (7.7-11.9, 1.7 × 104-2.2 × 104 cells mL- 1, and 0.01-0.09 glu-eq mg L- 1, respectively). Transport of bacteria and pEPS from sea-ice brines into snow was evident in 2010 but not 2011, a year with more extreme winter conditions of colder temperature, thinner snow, and stronger wind. By size fraction, the smallest EPS (< 0.1 µm) dominated (> 80%) total EPS in both ice and snow; the > 3 µm fraction of EPS in snow appeared to have an atmospheric source. Evaluation of membrane integrity by Live/Dead stain revealed a high percentage (85%) of live bacteria in saline snow, identifying this vast environment as a previously unrecognized microbial habitat.

  20. An Ultra-Wideband, Microwave Radar for Measuring Snow Thickness on Sea Ice and Mapping Near-Surface Internal Layers in Polar Firn

    NASA Technical Reports Server (NTRS)

    Panzer, Ben; Gomez-Garcia, Daniel; Leuschen, Carl; Paden, John; Rodriguez-Morales, Fernando; Patel, Azsa; Markus, Thorsten; Holt, Benjamin; Gogineni, Prasad

    2013-01-01

    Sea ice is generally covered with snow, which can vary in thickness from a few centimeters to >1 m. Snow cover acts as a thermal insulator modulating the heat exchange between the ocean and the atmosphere, and it impacts sea-ice growth rates and overall thickness, a key indicator of climate change in polar regions. Snow depth is required to estimate sea-ice thickness using freeboard measurements made with satellite altimeters. The snow cover also acts as a mechanical load that depresses ice freeboard (snow and ice above sea level). Freeboard depression can result in flooding of the snow/ice interface and the formation of a thick slush layer, particularly in the Antarctic sea-ice cover. The Center for Remote Sensing of Ice Sheets (CReSIS) has developed an ultra-wideband, microwave radar capable of operation on long-endurance aircraft to characterize the thickness of snow over sea ice. The low-power, 100mW signal is swept from 2 to 8GHz allowing the air/snow and snow/ ice interfaces to be mapped with 5 c range resolution in snow; this is an improvement over the original system that worked from 2 to 6.5 GHz. From 2009 to 2012, CReSIS successfully operated the radar on the NASA P-3B and DC-8 aircraft to collect data on snow-covered sea ice in the Arctic and Antarctic for NASA Operation IceBridge. The radar was found capable of snow depth retrievals ranging from 10cm to >1 m. We also demonstrated that this radar can be used to map near-surface internal layers in polar firn with fine range resolution. Here we describe the instrument design, characteristics and performance of the radar.

  1. The impact of early summer snow properties on land-fast sea-ice X-band backscatter

    NASA Astrophysics Data System (ADS)

    Paul, Stephan; Willmes, Sascha; Hoppmann, Mario; Hunkeler, Priska; Heinemann, Günther

    2014-05-01

    Snow cover on sea ice and its impact on radar backscatter, particularly after the onset of freeze-thaw processes requires increased understanding. We present a data set that comprises in-situ measured snow properties from the land-fast sea ice of the Atka Bay, Antarctica, in combination with high-resolution TerraSAR-X backscatter data. Both data sets are discussed for the transition period from austral winter to summer (November 2012 - January 2013). The changes in the seasonal snow cover are reflected in the evolution of TerraSAR-X backscatter. We are able to explain between 62 % and 80 % of the spatio-temporal variations of the TerraSAR-X backscatter signal with up to three snow-pack parameters by using a simple linear model. Especially after the onset of melt processes, the majority of the TerraSAR-X backscatter variations are influenced by snow depth, snow/ice-interface temperature and snow-pack grain size and thereby imply the potential to also retrieve snow physical properties from X-Band backscatter.

  2. NASA sea ice and snow validation plan for the Defense Meteorological Satellite Program special sensor microwave/imager

    NASA Technical Reports Server (NTRS)

    Cavalieri, Donald J. (editor); Swift, Calvin T. (editor)

    1987-01-01

    This document addresses the task of developing and executing a plan for validating the algorithm used for initial processing of sea ice data from the Special Sensor Microwave/Imager (SSMI). The document outlines a plan for monitoring the performance of the SSMI, for validating the derived sea ice parameters, and for providing quality data products before distribution to the research community. Because of recent advances in the application of passive microwave remote sensing to snow cover on land, the validation of snow algorithms is also addressed.

  3. Simulation of the melt season using a resolved sea ice model with snow cover and melt ponds

    NASA Astrophysics Data System (ADS)

    Skyllingstad, Eric D.; Shell, Karen M.; Collins, Lee; Polashenski, Chris

    2015-07-01

    A three-dimensional sea ice model is presented with resolved snow thickness variations and melt ponds. The model calculates heating from solar radiative transfer and simulates the formation and movement of brine/melt water through the ice system. Initialization for the model is based on observations of snow topography made during the summer melt seasons of 2009, 2010, and 2012 from a location off the coast of Barrow, AK. Experiments are conducted to examine the importance of snow properties and snow and ice thickness by comparing observed and modeled pond fraction and albedo. One key process simulated by the model is the formation of frozen layers in the ice as relatively warm fresh water grid cells freeze when cooled by adjacent, cold brine-filled grid cells. These layers prevent vertical drainage and lead to flooding of melt water commonly observed at the beginning of the melt season. Flooding persists until enough heat is absorbed to melt through the frozen layer. The resulting long-term melt pond coverage is sensitive to both the spatial variability of snow cover and the minimum snow depth. For thin snow cover, initial melting results in earlier, reduced flooding with a small change in pond fraction after drainage of the melt water. Deeper snow tends to generate a delayed, larger peak pond fraction before drainage.

  4. Characterizing the sea ice algae chlorophyll a-snow depth relationship over Arctic spring melt using transmitted irradiance

    NASA Astrophysics Data System (ADS)

    Campbell, K.; Mundy, C. J.; Barber, D. G.; Gosselin, M.

    2015-07-01

    The bottom ice algae chlorophyll a (chl a)-snow depth (HS) relationship was investigated for first-year sea ice in Allen Bay, Nunavut, from 27 April to 13 June 2011. A transmitted irradiance technique was used to estimate ice algae chl a throughout the period at time series locations covered and cleared of snow. Furthermore, chl a was estimated along transects perpendicular to dominant snowdrift orientation, and at short-term snow clear experimental sites. The association between chl a and most snow depths was characterized by four phases over the spring; light limitation (negative relationship), a transitional period (no relationship), chl a decline associated with higher transmitted irradiance (positive relationship), and a final phase of chl a decline independent from HS (no relationship). Algal chl a under areas cleared of snow was lower, reached zero chl a earlier and declined faster than snow-covered control sites. Results indicated that snow removal caused these chl a responses through photoinhibition, as well as ice melt later in the spring. Based on this research we propose that weather events that can rapidly melt the snowpack could significantly deplete bottom ice chl a and cause early termination of the bloom if they occur late in the spring.

  5. An AeroCom Assessment of Black Carbon in Arctic Snow and Sea Ice

    NASA Technical Reports Server (NTRS)

    Jiao, C.; Flanner, M. G.; Balkanski, Y.; Bauer, S. E.; Bellouin, N.; Bernsten, T. K.; Bian, H.; Carslaw, K. S.; Chin, M.; DeLuca, N.; Diehl, T.; Ghan, S. J.; Iversen, T.; Kirkevag, A.; Koch, D.; Liu, X.; Mann, G. W.; Penner, J. E.; Pitari, G.; Schulz, M.; Seland, O; Skeie, R. B.; Steenrod, S. D.; Stier, P.; Tkemura, T.

    2014-01-01

    Though many global aerosols models prognose surface deposition, only a few models have been used to directly simulate the radiative effect from black carbon (BC) deposition to snow and sea ice. Here, we apply aerosol deposition fields from 25 models contributing to two phases of the Aerosol Comparisons between Observations and Models (AeroCom) project to simulate and evaluate within-snow BC concentrations and radiative effect in the Arctic. We accomplish this by driving the offline land and sea ice components of the Community Earth System Model with different deposition fields and meteorological conditions from 2004 to 2009, during which an extensive field campaign of BC measurements in Arctic snow occurred. We find that models generally underestimate BC concentrations in snow in northern Russia and Norway, while overestimating BC amounts elsewhere in the Arctic. Although simulated BC distributions in snow are poorly correlated with measurements, mean values are reasonable. The multi-model mean (range) bias in BC concentrations, sampled over the same grid cells, snow depths, and months of measurements, are -4.4 (-13.2 to +10.7) ng/g for an earlier phase of AeroCom models (phase I), and +4.1 (-13.0 to +21.4) ng/g for a more recent phase of AeroCom models (phase II), compared to the observational mean of 19.2 ng/g. Factors determining model BC concentrations in Arctic snow include Arctic BC emissions, transport of extra-Arctic aerosols, precipitation, deposition efficiency of aerosols within the Arctic, and meltwater removal of particles in snow. Sensitivity studies show that the model-measurement evaluation is only weakly affected by meltwater scavenging efficiency because most measurements were conducted in non-melting snow. The Arctic (60-90degN) atmospheric residence time for BC in phase II models ranges from 3.7 to 23.2 days, implying large inter-model variation in local BC deposition efficiency. Combined with the fact that most Arctic BC deposition originates from extra-Arctic emissions, these results suggest that aerosol removal processes are a leading source of variation in model performance. The multi-model mean (full range) of Arctic radiative effect from BC in snow is 0.15 (0.07-0.25) W/sq m and 0.18 (0.06-0.28) W/sq m in phase I and phase II models, respectively. After correcting for model biases relative to observed BC concentrations in different regions of the Arctic, we obtain a multi-model mean Arctic radiative effect of 0.17 W/sq m for the combined AeroCom ensembles. Finally, there is a high correlation between modeled BC concentrations sampled over the observational sites and the Arctic as a whole, indicating that the field campaign provided a reasonable sample of the Arctic.

  6. An AeroCom Assessment of Black Carbon in Arctic Snow and Sea Ice

    SciTech Connect

    Jiao, C.; Flanner, M. G.; Balkanski, Y.; Bauer, S.; Bellouin, N.; Berntsen, T.; Bian, Huisheng; Carslaw, K. S.; Chin, Mian; De Luca, N.; Diehl, Thomas; Ghan, Steven J.; Iversen, T.; Kirkevag, A.; Koch, Dorothy; Liu, Xiaohong; Mann, G. W.; Penner, Joyce E.; Pitari, G.; Schulz, M.; Seland, O.; Skeie, R. B.; Steenrod, Stephen D.; Stier, P.; Takemura, T.; Tsigaridis, Kostas; van Noije, T.; Yun, Yuxing; Zhang, Kai

    2014-03-07

    Though many global aerosols models prognose surface deposition, only a few models have been used to directly simulate the radiative effect from black carbon (BC) deposition to snow and sea-ice. Here, we apply aerosol deposition fields from 25 models contributing to two phases of the Aerosol Comparisons between Observations and Models (AeroCom) project to simulate and evaluate within snow BC concentrations and radiative effect in the Arctic. We accomplish this by driving the offline land and sea-ice components of the Community Earth System Model with different deposition fields and meteorological conditions from 2004-2009, during which an extensive field campaign of BC measurements in Arctic snow occurred. We find that models generally underestimate BC concentrations in snow in northern Russia and Norway, while overestimating BC amounts elsewhere in the Arctic. Although simulated BC distributions in snow are poorly correlated with measurements, mean values are reasonable. The multi-model mean (range) bias in BC concentrations, sampled over the same grid cells, snow depths, and months of measurements, are -4.4 (-13.2 to +10.7) ng g?1 for an earlier Phase of AeroCom models (Phase I), and +4.1 (-13.0 to +21.4) ng g?1 for a more recent Phase of AeroCom models (Phase II), compared to the observational mean of 19.2 ng g?1. Factors determining model BC concentrations in Arctic snow include Arctic BC emissions, transport of extra-Arctic aerosols, precipitation, deposition efficiency of aerosols within the Arctic, and meltwater removal of particles in snow. Sensitivity studies show that the model–measurement evaluation is only weakly affected by meltwater scavenging efficiency because most measurements were conducted in non-melting snow. The Arctic (60-90?N) atmospheric residence time for BC in Phase II models ranges from 3.7 to 23.2 days, implying large inter-model variation in local BC deposition efficiency. Combined with the fact that most Arctic BC deposition originates from extra-Arctic emissions, these results suggest that aerosol removal processes are a leading source of variation in model performance. The multi-model mean (full range) of Arctic radiative effect from BC in snow is 0.15 (0.07-0.25) W m?2 and 0.18 (0.06-0.28) W m?2 in Phase I and Phase II models, respectively. After correcting for model biases relative to observed BC concentrations in different regions of the Arctic, we obtain a multi-model mean Arctic radiative effect of 0.17 W m?2 for the combined AeroCom ensembles. Finally, there is a high correlation between modeled BC concentrations sampled over the observational sites and the Arctic as a whole, indicating that the field campaign provided a reasonable sample of the Arctic.

  7. Snow and Ice.

    ERIC Educational Resources Information Center

    Minneapolis Independent School District 275, Minn.

    This experimental edition provides a number of activities useful for investigating snow and ice with elementary school children. Commencing with games with ice cubes, the activities lead through studies of snowflakes, snowdrifts, effects of wind and obstacles on the shape and formation of drifts, to a study of animals living under snow. The…

  8. An Ultra Wide-Band Radar Altimeter for Ice Sheet Surface Elevation and Snow Cover Over Sea Ice Measurement

    NASA Astrophysics Data System (ADS)

    Patel, A. E.; Gogineni, P. S.; Leuschen, C.; Rodriguez-Morales, F.; Panzer, B.

    2010-12-01

    The Ice sheets of Greenland and Antarctica are losing mass at a rapid rate and there has been significant decrease in sea ice volume over the last few years. CryoSat-II with optimized radar altimeter for ice-sheet and sea ice surface elevation measurements is launched. We developed ultra wide-band FM-CW radar that operates over the frequency range from 13-17 GHz for airborne measurements. The radar is designed to provide high-resolution surface-elevation data and also map near surface layers in polar firn with high precision. It is designed to generate an ultra linear transmit chirp using a fast settling PLL with a reference signal from Direct Digital Synthesizer (DDS). The pulse length of the transmit chirp is 240-us and pulse repetition frequency is 2-KHz. The peak transmit power of the system is 100-mW, radiated using horn antennas. The radar was deployed in Greenland and Antarctica in 2009-10 as a part of Operation Ice Bridge campaign to collect data in conjunction with other instruments including Airborne Topographic Mapper (ATM) and Digital Mapping System Camera (DMS). The radar also collected data under the Cryosat-II path. This paper will provide an overview of the Ku-Band radar design along with results from the 2009-2010 field campaigns. The data collected over polar firn shows near surface internal layers down to a depth of about 15-m with a resolution of 15-cm. When flying over sea ice the radar provides snow cover thickness data to a depth of about 0.5-m. Even over highly crevassed areas, such as outlet glaciers, the radar is able to detect large surface elevation changes of a few tens of meters with high resolution.

  9. Correlations between Inter-Annual Variations in Arctic Sea Ice Extent, Greenland Surface Melt, and Boreal Snow Cover

    NASA Technical Reports Server (NTRS)

    Markus, Thorstena; Stroeve, Julienne C.; Armstrong, Richard L.

    2004-01-01

    Intensification of global warming in recent decades has caused a rise of interest in year-to-year and decadal-scale climate variability in the Arctic. This is because the Arctic is believed to be one of the most sensitive and vulnerable regions to climatic changes. For over two decades satellite passive microwave observations have been utilized to continuously monitor the Arctic environment. Derived parameters include sea ice cover, snow cover and snow water equivalent over land, and Greenland melt extent and length of melt season. Most studies have primarily concentrated on trends and variations of individual variables. In this study we investigated how variations in sea ice cover, Greenland surface melt, and boreal snow cover are correlated. This was done on hemispheric as well as on regional scales. Latest results will be presented including data from the summer of 2004.

  10. Derivation and Validation of Snow Depth over Arctic Sea Ice by Integrating Snow Radar, Airborne Topographic Mapper, and In-Situ Measurement Data from the Greenland 2009 IceBridge Campaign

    NASA Astrophysics Data System (ADS)

    Johnson, M. P.; Perkovic, D.; Panzer, B.; Holt, B.; Leuschen, C.

    2011-12-01

    Using NASA's Operation IceBridge airborne data, this paper examines the derivation of snow depth on sea ice using measurements from two instruments, the Snow Radar and Atmospheric Topographic Mapper (ATM), taken off the northern coast of Greenland in April 2009. In-situ measurements of sea ice thickness, freeboard and snow depth obtained at the GreenArc ice camp are used as comparison points to the estimates made where possible. We also present range estimation and geolocation methodology for the Snow Radar data and analyze possible sources of error within these estimates. The Snow Radar is an ultra-wideband (2 - 6.5 GHz) Frequency Modulated Continuous-Wave (FMCW) radar that penetrates the snow layer and is able to discern both the snow-ice (SI) and the snow-air (SA) interfaces. The detected radar backscatter signature contains peaks in the return where the boundaries occur, with the SI interface having a stronger power return than the SA boundary. Level 1B data of radar echo strength range profiles are used to generate estimates of the distance from the radar antenna to the SI and SA interfaces. Aircraft position and attitude data are then used to georeference the radar range data as height estimates above the WGS-84 ellipsoid. The ATM is a conically scanning LIDAR that measures the range from the aircraft to the Earth's surface. Because the laser does not penetrate the snow or ice surface, the surface is interpreted to be the SA interface or the ice-air (IA) interface in the case of bare ice. Level 1B ATM data of WGS-84 referenced elevations are used in the comparison. Validation of the ATM-provided elevations and calibration of the Snow Radar-derived elevations were performed using data collected over GPS surveyed areas of the Thule air force base in Greenland. ATM surface height elevations will be shown to agree with the GPS surveyed area to within 10 cm. Initial calibrations of the radar estimated heights with the GPS surveyed area show an offset of approximately 1 m. When the radar measurements are corrected for the estimated offset and compared to the ATM measurements over bare ice, the two will be shown to be in very good agreement. This paper will then show how the collocated Snow Radar and ATM measurements are used to derive estimates of snow depth over sea ice, which are also compared where possible with the snow depth measurements.

  11. Recent progress in snow and ice research

    SciTech Connect

    Richter-menge, J.A.; Colbeck, S.C.; Jezek, K.C. )

    1991-01-01

    A review of snow and ice research in 1987-1990 is presented, focusing on the effects of layers in seasonal snow covers, ice mechanics on fresh water and sea ice, and remote sensig of polar ice sheets. These topics provide useful examples of general needs in snow and ice research applicable to most areas, such as better representation in models of detailed processes, controlled laboratory experiments to quantify processes, and field studies to provide the appropriate context for interpretation of processes from remote sensing.

  12. Sea ice - Multiyear cycles and white ice

    NASA Technical Reports Server (NTRS)

    Ledley, T. S.

    1985-01-01

    The multiyear thickness cycles represent one of the interesting features of the sea ice studies performed by Semtner (1976) and Washington et al. (1976) with simple thermodynamic models of sea ice. In the present article, a description is given of results which show that the insulating effect of snow on the surface of the sea ice is important in producing these multiyear cycles given the physics included in the model. However, when the formation of white ice is included, the cycles almost disappear. White ice is the ice which forms at the snow-ice interface when the snow layer becomes thick enough to depress the ice below the water level. Water infiltrates the snow by coming through the ice at leads and generally freezes there, forming white ice.

  13. A Comparison of Snow Depth on Sea Ice Retrievals Using Airborne Altimeters and an AMSR-E Simulator

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Marksu, T.; Ivanoff, A.; Miller, J. A.; Brucker, L.; Sturm, M.; Maslanik, J. A.; Heinrichs, J. F.; Gasiewski, A.; Leuschen, C.; Krabill, W.; Sonntag, J.

    2011-01-01

    A comparison of snow depths on sea ice was made using airborne altimeters and an Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) simulator. The data were collected during the March 2006 National Aeronautics and Space Administration (NASA) Arctic field campaign utilizing the NASA P-3B aircraft. The campaign consisted of an initial series of coordinated surface and aircraft measurements over Elson Lagoon, Alaska and adjacent seas followed by a series of large-scale (100 km ? 50 km) coordinated aircraft and AMSR-E snow depth measurements over portions of the Chukchi and Beaufort seas. This paper focuses on the latter part of the campaign. The P-3B aircraft carried the University of Colorado Polarimetric Scanning Radiometer (PSR-A), the NASA Wallops Airborne Topographic Mapper (ATM) lidar altimeter, and the University of Kansas Delay-Doppler (D2P) radar altimeter. The PSR-A was used as an AMSR-E simulator, whereas the ATM and D2P altimeters were used in combination to provide an independent estimate of snow depth. Results of a comparison between the altimeter-derived snow depths and the equivalent AMSR-E snow depths using PSR-A brightness temperatures calibrated relative to AMSR-E are presented. Data collected over a frozen coastal polynya were used to intercalibrate the ATM and D2P altimeters before estimating an altimeter snow depth. Results show that the mean difference between the PSR and altimeter snow depths is -2.4 cm (PSR minus altimeter) with a standard deviation of 7.7 cm. The RMS difference is 8.0 cm. The overall correlation between the two snow depth data sets is 0.59.

  14. Diversity and characterization of mercury-resistant bacteria in snow, freshwater and sea-ice brine from the High Arctic.

    PubMed

    Møller, Annette K; Barkay, Tamar; Abu Al-Soud, Waleed; Sørensen, Søren J; Skov, Henrik; Kroer, Niels

    2011-03-01

    It is well-established that atmospheric deposition transports mercury from lower latitudes to the Arctic. The role of bacteria in the dynamics of the deposited mercury, however, is unknown. We characterized mercury-resistant bacteria from High Arctic snow, freshwater and sea-ice brine. Bacterial densities were 9.4 × 10(5), 5 × 10(5) and 0.9-3.1 × 10(3) cells mL(-1) in freshwater, brine and snow, respectively. Highest cultivability was observed in snow (11.9%), followed by freshwater (0.3%) and brine (0.03%). In snow, the mercury-resistant bacteria accounted for up to 31% of the culturable bacteria, but <2% in freshwater and brine. The resistant bacteria belonged to the Alpha-, Beta- and Gammaproteobacteria, Firmicutes, Actinobacteria, and Bacteriodetes. Resistance levels of most isolates were not temperature dependent. Of the resistant isolates, 25% reduced Hg(II) to Hg(0). No relation between resistance level, ability to reduce Hg(II) and phylogenetic group was observed. An estimation of the potential bacterial reduction of Hg(II) in snow suggested that it was important in the deeper snow layers where light attenuation inhibited photoreduction. Thus, by reducing Hg(II) to Hg(0), mercury-resistant bacteria may limit the supply of substrate for methylation processes and, hence, contribute to lowering the risk that methylmercury is being incorporated into the Arctic food chains. PMID:21166687

  15. Hyperparameter Classification of Arctic Sea Ice and Snow Based on Aerial Laser Data, Passive Microwave Data and Field Data

    NASA Astrophysics Data System (ADS)

    Herzfeld, U. C.; Maslanik, J.; Williams, S.; Sturm, M.; Cavalieri, D.

    2006-12-01

    In the past year, the Arctic sea-ice cover has been shrinking at an alarming rate. Remote-sensing technologies provide opportunities for observations of the sea ice at unprecedented repetition rates and spatial resolutions. The advance of new observational technologies is not only fascinating, it also brings with it the challenge and necessity to derive adequate new geoinformatical and geomathematical methods as a basis for analysis and geophysical interpretation of new data types. Our research includes validation and analysis of NASA EOS data, development of observational instrumentation and advanced geoinformatics. In this talk we emphasize the close linkage between technological development and geoinformatics along case studies of sea-ice near Point Barrow, Alaska, based on the following data types: AMSR-E and PSR passive microwave data, RADARSAT and ERS SAR data, manually-collected snow-depth data and laser-elevation data from unmanned aerial vehicles. The hyperparameter concept is introduced to facilitate characterization and classification of the same sea-ice properties and spatial structures from these data sets, which differ with respect to spatial resolution, measured parameters and observed geophysical variables. Mathematically, this requires parameter identification in undersampled, oversampled or overprinted situations.

  16. The Role of Snow and Ice in the Climate System

    ScienceCinema

    Barry, Roger G.

    2009-09-01

    Global snow and ice cover (the 'cryosphere') plays a major role in global climate and hydrology through a range of complex interactions and feedbacks, the best known of which is the ice - albedo feedback. Snow and ice cover undergo marked seasonal and long term changes in extent and thickness. The perennial elements - the major ice sheets and permafrost - play a role in present-day regional and local climate and hydrology, but the large seasonal variations in snow cover and sea ice are of importance on continental to hemispheric scales. The characteristics of these variations, especially in the Northern Hemisphere, and evidence for recent trends in snow and ice extent are discussed.

  17. The Role of Snow and Ice in the Climate System

    SciTech Connect

    Barry, Roger G.

    2007-12-19

    Global snow and ice cover (the 'cryosphere') plays a major role in global climate and hydrology through a range of complex interactions and feedbacks, the best known of which is the ice - albedo feedback. Snow and ice cover undergo marked seasonal and long term changes in extent and thickness. The perennial elements - the major ice sheets and permafrost - play a role in present-day regional and local climate and hydrology, but the large seasonal variations in snow cover and sea ice are of importance on continental to hemispheric scales. The characteristics of these variations, especially in the Northern Hemisphere, and evidence for recent trends in snow and ice extent are discussed.

  18. Snow cover and short-term synoptic events drive biogeochemical dynamics in winter Weddell Sea pack ice (AWECS cruise - June to August 2013)

    NASA Astrophysics Data System (ADS)

    Tison, Jean-Louis; Delille, Bruno; Dieckmann, Gherard; de Jong, Jeroen; Janssens, Julie; Rintala, Janne; Luhtanen, Annemari; Gussone, Niklaus; Uhlig, Christiane; Nomura, Daïki; Schoemann, Véronique; Zhou, Jiayun; Carnat, Gauthier; Fripiat, François

    2014-05-01

    This paper presents the preliminary results of an integrated multidisciplinary study of pack ice biogeochemistry in the Weddell Sea during the winter 2013 (June-August). The sea ice biogeochemistry group was one of the components of the AWECS (Antarctic Winter Ecosystem and Climate Study) cruise (Polarstern ANTXXIX-6). A total of 12 stations were carried out by the sea ice biogeochemistry group, which collected a suite of variables in the fields of physics, inorganic chemistry, gas content and composition, microbiology, biogeochemistry, trace metals and the carbonate system in order to give the best possible description of the sea ice cover and its interactions at interfaces. Samples were collected in the atmosphere above (gas fluxes), in the snow cover, in the bulk ice (ice cores), in the brines (sackholes) and in the sea water below (0m, 1m, 30 m). Here we present the results of basic physico-chemical (T° , bulk ice salinity, brine volumes, brine salinity, Rayleigh numbers) and biological (Chla) measurements in order to give an overview of the general status of the Weddell Sea winter pack ice encountered, and discuss how it controls climate relevant biogeochemical processes. Our results from the first set of 9 stations, mainly sampled along the Greenwich meridian and the easternmost part of the Weddell Sea definitively refute the view of a biogeochemically 'frozen' sea ice during the Winter. This has already been demonstrated for the Spring and Summer, but we now see that sea ice sustains considerable biological stocks and activities throughout the Winter, despite the reduced amount of available PAR radiation. Accretion of the snow cover appears to play an essential role in driving biogeochemical activity, through warming from insulation, thus favouring brine transport, be it through potential convection, surface brine migration (brine tubes) or flooding. This results in a 'widening' of the internal autumn layer (quite frequent in this rafting-dominated sea ice cover) and increase of the chla burden with age. Results from the second set of 3 stations in the western branch of the Weddell Sea gyre confirm that it comprises a mixture of older fast/second year ice floes with younger first-year ice floes. The older ice had the highest Chlaconcentrations of the entire cruise (>200 ?gl-1), in an internal community enclosed within desalinized impermeable upper and lower layers. The first-year ice differs from that in the eastern Weddell Sea as it is dominated by columnar ice and (weak) algal communities are only found on the bottom or near the surface (no internal maximum).

  19. Observations of the PCB distribution within and in-between ice, snow, ice-rafted debris, ice-interstitial water, and seawater in the Barents Sea marginal ice zone and the North Pole area.

    PubMed

    Gustafsson, O; Andersson, P; Axelman, J; Bucheli, T D; Kömp, P; McLachlan, M S; Sobek, A; Thörngren, J-O

    2005-04-15

    To evaluate the two hypotheses of locally elevated exposure of persistent organic pollutants (POPs) in ice-associated microenvironments and ice as a key carrier for long-range transport of POPs to the Arctic marginal ice zone (MIZ), dissolved and particulate polychlorinated biphenyls (PCBs) were analyzed in ice, snow, ice-interstitial water (IIW), seawater in the melt layer underlying the ice, and in ice-rafted sediment (IRS) from the Barents Sea MIZ to the high Arctic in the summer of 2001. Ultra-clean sampling equipment and protocols were specially developed for this expedition, including construction of a permanent clean room facility and a stainless steel seawater intake system on the I/B ODEN as well as two mobile 370 l ice-melting systems. Similar concentrations were found in several ice-associated compartments. For instance, the concentration of one of the most abundant congeners, PCB 52, was typically on the order of 0.1-0.3 pg l(-1) in the dissolved (melted) phase of the ice, snow, IIW, and underlying seawater while its particulate organic-carbon (POC) normalized concentrations were around 1-3 ng gPOC(-1) in the ice, snow, IIW, and IRS. The solid-water distribution of PCBs in ice was well correlated with and predictable from K(ow) (ice log K(oc)-log K(ow) regressions: p<0.05, r2=0.78-0.98, n=9), indicating near-equilibrium partitioning of PCBs within each local ice system. These results do generally not evidence the existence of physical microenvironments with locally elevated POP exposures. However, there were some indications that the ice-associated system had harbored local environments with higher exposure levels earlier/before the melting/vegetative season, as a few samples had PCB concentrations elevated by factors of 5-10 relative to the typical values, and the elevated levels were predominantly found at the station where melting had putatively progressed the least. The very low PCB concentrations and absence of any significant concentration gradients, both in-between different matrices and over the Eurasian Arctic basin scale, suggest that ice is not an important long-range transport purveyor of POPs to the Arctic MIZ ecosystem. PMID:15866279

  20. Impact of snow accumulation on CryoSat-2 range retrievals over Arctic sea ice: An observational approach with buoy data

    NASA Astrophysics Data System (ADS)

    Ricker, Robert; Hendricks, Stefan; Perovich, Donald K.; Helm, Veit; Gerdes, Rüdiger

    2015-06-01

    Radar altimetry measurements of the current satellite mission CryoSat-2 show an increase of Arctic sea ice thickness in autumn 2013, compared to previous years but also related to March 2013. Such an increase over the melting season seems unlikely and needs to be investigated. Recent studies show that the influence of the snow cover is not negligible and can highly affect the CryoSat-2 range retrievals if it is assumed that the main scattering horizon is given by the snow-ice interface. Our analysis of Arctic ice mass balance buoy records and coincident CryoSat-2 data between 2012 and 2014 adds observational evidence to these findings. Linear trends of snow and ice freeboard measurements from buoys and nearby CryoSat-2 freeboard retrievals are calculated during accumulation events. We find a positive correlation between buoy snow freeboard and CryoSat-2 freeboard estimates, revealing that early snow accumulation might have caused a bias in CryoSat-2 sea ice thickness in autumn 2013.

  1. Sea Ice

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.; Cavalieri, Donald J.

    2005-01-01

    Sea ice covers vast areas of the polar oceans, with ice 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 ice 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 ice 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 ice covers, and many studies suggest possible connections between the ice 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 ice coverage in the Arctic and increased ice coverage in the Antarctic from late 1978 through the end of 2003, with the Antarctic ice increases following marked decreases in the Antarctic ice during the 1970s. For a detailed picture of the seasonally varying ice cover at the start of the 21st century, this chapter includes ice 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 ice covers from the 1970s through 2003.

  2. Sea Ice

    NASA Technical Reports Server (NTRS)

    Perovich, D.; Gerland, S.; Hendricks, S.; Meier, Walter N.; Nicolaus, M.; Richter-Menge, J.; Tschudi, M.

    2013-01-01

    During 2013, Arctic sea ice extent remained well below normal, but the September 2013 minimum extent was substantially higher than the record-breaking minimum in 2012. Nonetheless, the minimum was still much lower than normal and the long-term trend Arctic September extent is -13.7 per decade relative to the 1981-2010 average. The less extreme conditions this year compared to 2012 were due to cooler temperatures and wind patterns that favored retention of ice through the summer. Sea ice thickness and volume remained near record-low levels, though indications are of slightly thicker ice compared to the record low of 2012.

  3. Role of sea surface temperature, Arctic sea ice and Siberian snow in forcing the atmospheric circulation in winter of 2012-2013

    NASA Astrophysics Data System (ADS)

    Peings, Yannick; Magnusdottir, Gudrun

    2015-09-01

    During the 2012-2013 winter, the negative phase of the North Atlantic Oscillation (NAO) predominated, resulting in a cold winter over Europe and northern Asia punctuated by episodes of frigid weather. This climate anomaly is part of a recent trend towards negative values of the NAO index that has occurred over recent winters. The negative trend of the NAO may be related to atmospheric internal variability but it may also be partly forced by slowly varying components of the climate system. In the present study, we investigate the influence of surface conditions on the atmospheric circulation for the 2012-2013 winter using an atmospheric global climate model. In particular, the role of low Arctic sea ice concentration, warm tropical/North Atlantic sea surface temperature and positive Siberian snow cover anomalies are isolated by prescribing them in a set of different numerical experiments. Our simulations suggest that each of these surface forcings favored a negative NAO during the 2012-2013 winter. In our model, the combined NAO response to tropical/North Atlantic SST, Arctic sea ice and Siberian snow anomalies accounts for about 30 % of the observed NAO anomaly. Different physical mechanisms are explored to elucidate the atmospheric responses and are shown to involve both tropical and extratropical processes.

  4. A Simple Scheme for Estimating Turbulent Heat Flux over Landfast Arctic Sea Ice from Dry Snow to Advanced Melt

    NASA Astrophysics Data System (ADS)

    Raddatz, R. L.; Papakyriakou, T. N.; Else, B. G.; Swystun, K.; Barber, D. G.

    2015-05-01

    We describe a dynamic-parameter aggregation scheme to estimate hourly turbulent heat fluxes over landfast sea ice during the transition from winter to spring. Hourly albedo measurements are used to track the morphology of the surface as it evolved from a fairly smooth homogeneous dry snow surface to a rougher heterogeneous surface with spatially differential melting and melt ponds. The estimates of turbulent heat fluxes for 928 h are compared with eddy-covariance measurements. The model performance metrics (W m) for sensible heat flux were found to be: mean bias , root-mean-square error 6 and absolute accuracy 4, and for latent heat flux near zero, 3 and 2, respectively. The correlation coefficient between modelled and measured sensible heat fluxes was 0.82, and for latent heat fluxes 0.88. The turbulent heat fluxes were estimated more accurately without adjustments than with adjustments for atmospheric stability based on the bulk Richardson number. Overall, and across all metrics for both sensible and latent heat fluxes, the dynamic-parameter aggregation scheme outperformed the static Community Ice (C-ICE) scheme, part of the Community Climate System model, applied to the same winter-to-spring transition period.

  5. The role of sea ice dynamics in global climate change

    NASA Technical Reports Server (NTRS)

    Hibler, William D., III

    1992-01-01

    The topics covered include the following: general characteristics of sea ice drift; sea ice rheology; ice thickness distribution; sea ice thermodynamic models; equilibrium thermodynamic models; effect of internal brine pockets and snow cover; model simulations of Arctic Sea ice; and sensitivity of sea ice models to climate change.

  6. A Blowing Snow Model for Ice Shelf Rifts

    NASA Astrophysics Data System (ADS)

    Leonard, K. C.; Tremblay, L.; Macayeal, D. R.

    2005-12-01

    Ice melange (a mixture of snow, marine ice, and ice talus) may play various roles in the rates of propagation of iceberg-calving rifts through Antarctic ice shelves. This modeling study examines the role of windblown snow in the formation and maintenance of ice melange in the "nascent rift" in the Ross Ice Shelf (78 08'S, 178 29'W). The rift axis is perpendicular to the regional wind direction, allowing us to employ a two-dimensional blowing snow model. The Piektuk-Tuvaq blowing snow model (Dery and Tremblay, 2004) adapted the Piektuk blowing snow model for use in sea ice environments by including parameterization for open-water leads within the sea ice. This version of the model was used to study the initial conditions of a freshly-opened rift, as the input of blowing snow into the seawater within the rift promotes marine ice formation by cooling and freshening the surface water. We adapted the Piektuk-Tuvaq model both for the local climatic conditions and to incorporate the geometry of the rift, which is 30m deep and 100m wide (far deeper than a lead). We present the evolution of the topography within the rift for two cases. The first is an ice melange composed exclusively of snow and marine ice, the second uses an initial topography including large chunks of ice talus.

  7. Primary Production in Antarctic Sea Ice

    NASA Technical Reports Server (NTRS)

    Arrigo, Kevin R.; Worthen, Denise L.; Lizotte, Michael P.; Dixon, Paul; Dieckmann, Gerhard

    1997-01-01

    A numerical model shows that in Antarctic sea ice, increased flooding in regions with thick snow cover enhances primary production in the infiltration (surface) layer. Productivity in the freeboard (sea level) layer is also determined by sea ice porosity, which varies with temperature. Spatial and temporal variation in snow thickness and the proportion of first-year ice thus determine regional differences in sea ice primary production. Model results show that of the 40 tera-grams of carbon produced annually in the Antarctic ice pack, 75 percent was associated with first-year ice and nearly 50 percent was produced in the Weddell Sea.

  8. Rubber friction on ice and snow surfaces 

    E-print Network

    Skouvaklis, Gerasimos

    2011-06-28

    The friction of rubber on ice and snow surfaces is complex. Deeper scientific understanding is important for optimising performance of tyres in winter. Rubber, ice and snow systems exhibit frictional behaviour which ...

  9. Frost flowers growing in the Arctic ocean-atmosphere-sea ice-snow interface: 1. Chemical composition

    NASA Astrophysics Data System (ADS)

    Douglas, Thomas A.; Domine, Florent; Barret, Manuel; Anastasio, Cort; Beine, Harry J.; Bottenheim, Jan; Grannas, Amanda; Houdier, Stephan; Netcheva, Stoyka; Rowland, Glenn; Staebler, Ralf; Steffen, Alexandra

    2012-07-01

    Frost flowers, intricate featherlike crystals that grow on refreezing sea ice leads, have been implicated in lower atmospheric chemical reactions. Few studies have presented chemical composition information for frost flowers over time and many of the chemical species commonly associated with Polar tropospheric reactions have never been reported for frost flowers. We undertook this study on the sea ice north of Barrow, Alaska to quantify the major ion, stable oxygen and hydrogen isotope, alkalinity, light absorbance by soluble species, organochlorine, and aldehyde composition of seawater, brine, and frost flowers. For many of these chemical species we present the first measurements from brine or frost flowers. Results show that major ion and alkalinity concentrations, stable isotope values, and major chromophore (NO3- and H2O2) concentrations are controlled by fractionation from seawater and brine. The presence of these chemical species in present and future sea ice scenarios is somewhat predictable. However, aldehydes, organochlorine compounds, light absorbing species, and mercury (part 2 of this research and Sherman et al. (2012)) are deposited to frost flowers through less predictable processes that probably involve the atmosphere as a source. The present and future concentrations of these constituents in frost flowers may not be easily incorporated into future sea ice or lower atmospheric chemistry scenarios. Thinning of Arctic sea ice will likely present more open sea ice leads where young ice, brine, and frost flowers form. How these changing ice conditions will affect the interactions between ice, brine, frost flowers and the lower atmosphere is unknown.

  10. Mercuric reductase genes (merA) and mercury resistance plasmids in High Arctic snow, freshwater and sea-ice brine.

    PubMed

    Møller, Annette K; Barkay, Tamar; Hansen, Martin A; Norman, Anders; Hansen, Lars H; Sørensen, Søren J; Boyd, Eric S; Kroer, Niels

    2014-01-01

    Bacterial reduction in Hg(2+) to Hg(0) , mediated by the mercuric reductase (MerA), is important in the biogeochemical cycling of Hg in temperate environments. Little is known about the occurrence and diversity of merA in the Arctic. Seven merA determinants were identified among bacterial isolates from High Arctic snow, freshwater and sea-ice brine. Three determinants in Bacteriodetes, Firmicutes and Actinobacteria showed < 92% (amino acid) sequence similarity to known merA, while one merA homologue in Alphaproteobacteria and 3 homologues from Betaproteobacteria and Gammaproteobacteria were > 99% similar to known merA's. Phylogenetic analysis showed the Bacteroidetes merA to be part of an early lineage in the mer phylogeny, whereas the Betaproteobacteria and Gammaproteobacteria merA appeared to have evolved recently. Several isolates, in which merA was not detected, were able to reduce Hg(2+) , suggesting presence of unidentified merA genes. About 25% of the isolates contained plasmids, two of which encoded mer operons. One plasmid was a broad host-range IncP-? plasmid. No known incompatibility group could be assigned to the others. The presence of conjugative plasmids, and an incongruent distribution of merA within the taxonomic groups, suggests horizontal transfer of merA as a likely mechanism for High Arctic microbial communities to adapt to changing mercury concentration. PMID:23909591

  11. NASA Sea Ice and Snow Validation Program for the DMSP SSM/I: NASA DC-8 flight report

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.

    1988-01-01

    In June 1987 a new microwave sensor called the Special Sensor Microwave Imager (SSM/I) was launched as part of the Defense Meteorological Satellite Program (DMSP). In recognition of the importance of this sensor to the polar research community, NASA developed a program to acquire the data, to convert the data into sea ice parameters, and finally to validate and archive both the SSM/I radiances and the derived sea ice parameters. Central to NASA's sea ice validation program was a series of SSM/I aircraft underflights with the NASA DC-8 airborne Laboratory. The mission (the Arctic '88 Sea Ice Mission) was completed in March 1988. This report summarizes the mission and includes a summary of aircraft instrumentation, coordination with participating Navy aircraft, flight objectives, flight plans, data collected, SSM/I orbits for each day during the mission, and lists several piggyback experiments supported during this mission.

  12. Biogeochemistry in Sea Ice: CICE model developments

    SciTech Connect

    Jeffery, Nicole; Hunke, Elizabeth; Elliott, Scott; Turner, Adrian

    2012-06-18

    Polar primary production unfolds in a dynamic sea ice environment, and the interactions of sea ice with ocean support and mediate this production. In spring, for example, fresh melt water contributes to the shoaling of the mixed layer enhancing ice edge blooms. In contrast, sea ice formation in the fall reduces light penetration to the upper ocean slowing primary production in marine waters. Polar biogeochemical modeling studies typically consider these types of ice-ocean interactions. However, sea ice itself is a biogeochemically active medium, contributing a significant and, possibly, essential source of primary production to polar regions in early spring and fall. Here we present numerical simulations using the Los Alamos Sea Ice Model (CICE) with prognostic salinity and sea ice biogeochemistry. This study investigates the relationship between sea ice multiphase physics and sea ice productivity. Of particular emphasis are the processes of gravity drainage, melt water flushing, and snow loading. During sea ice formation, desalination by gravity drainage facilitates nutrient exchange between ocean and ice maintaining ice algal blooms in early spring. Melt water flushing releases ice algae and nutrients to underlying waters limiting ice production. Finally, snow loading, particularly in the Southern Ocean, forces sea ice below the ocean surface driving an upward flow of nutrient rich water into the ice to the benefit of interior and freeboard communities. Incorporating ice microphysics in CICE has given us an important tool for assessing the importance of these processes for polar algal production at global scales.

  13. Boundary layer dynamics during the Ocean-Atmosphere-Sea-Ice-Snow (OASIS) 2009 experiment at Barrow, AK

    NASA Astrophysics Data System (ADS)

    Boylan, Patrick; Helmig, Detlev; Staebler, Ralf; Turnipseed, Andrew; Fairall, Chris; Neff, William

    2014-03-01

    Three-dimensional atmospheric turbulence measurements were conducted from seven sonic anemometers on two different towers in Barrow, AK, during the spring of 2009 as part of the Ocean-Atmosphere-Sea-Ice-Snow (OASIS) campaign. This was the largest number of side-by-side atmospheric turbulence measurements in the Arctic at one time. These analyses allowed for (1) a comparison of the instrumental measurement approaches and (2) a comparison of the variability of the lower atmospheric surface layer at these measurement heights and tower sites. Friction velocity estimates were affected for a sonic anemometer that was operated on the tower in the near vicinity of a building module. Boundary layer height (BLH) was estimated from sonic anemometer measurements based both on a turbulence variable estimator and a temperature gradient method. Results from both methods were compared to radiosonde-estimated BLH and generally underestimated the BLH for shallower depths. Conditions with low BLH (< 100 m) often lasted for several days. The seven ozone depletion events (ODE) that were observed during the OASIS campaign had a tendency of coinciding with BLH of less than 50 m and stable atmospheric conditions; however, there was not a clear relationship between the occurrence of ODE and wind speed or wind direction as ODE occurred under a wide range of conditions of BLH, wind speed, local wind direction, and atmospheric stability. Comparisons of these surface layer dynamics to sites in Antarctica and Greenland reveal that boundary layer dynamics are not the primary driving force that fosters the unique ozone chemistry at this coastal Arctic site.

  14. An eight-year (1987-1994) time series of rainfall, clouds, water vapor, snow cover, and sea ice derived from SSM/I measurements

    SciTech Connect

    Ferraro, R.R.; Weng, F.; Grody, N.C.

    1996-05-01

    The Special Microwave Sensor/Imager (SSM/I), first placed into operation in July 1987, has been making measurements of earth-emitted radiation for over eight years. These data are used to estimate both atmospheric and surface hydrological parameters and to generate a time series of global monthly mean products averaged to a 1{degrees} lat x 1{degrees} long grid. Specifically, this includes monthly estimates of rainfall and its frequency, cloud liquid water and cloud frequency, water vapor, snow cover frequency, and sea ice frequency. This study uses seasonal mean values to demonstrate the spatial and temporal distributions of the hydrological variables. Examples of interannual variability such as the 1993 flooding in the Mississippi Valley and the 1992-93 snow coverage changes over the United States are used to demonstrate the utility of these data for regional application. 28 refs., 16 figs., 4 tabs.

  15. Summer Arctic Atmospheric Circulation Response to Spring Eurasian Snow Cover and its Possible Linkage to Accelerated Sea Ice Decrease

    NASA Astrophysics Data System (ADS)

    Matsumura, S.; Zhang, X.; Yamazaki, K.

    2014-12-01

    Anticyclonic circulation has intensified over the Arctic Ocean in summer during recent decades. However, the underlying mechanism is, as yet, not well understood. Here we show that earlier spring Eurasian snowmelt leads to anomalously negative sea level pressure (SLP) over Eurasia and positive SLP over the Arctic, which has strong projection on the negative phase of the Northern Annular Mode (NAM) in summer through the wave-mean flow interaction. Specifically, earlier spring snowmelt over Eurasia leads to a warmer land surface, due to reduced surface albedo. The warmed surface amplifies stationary Rossby waves, leading to a deceleration of the subpolar jet. As a consequence, rising motion is enhanced over the land, and compensating subsidence and adiabatic heating occur in the Arctic troposphere, forming the negative NAM. The intensified anticyclonic circulation has played a contributing role in accelerating the sea ice decline observed during the last two decades. The results here provide important information for improving seasonal prediction of summer sea ice cover.

  16. [Spectral features analysis of sea ice in the Arctic Ocean].

    PubMed

    Ke, Chang-qing; Xie, Hong-jie; Lei, Rui-bo; Li, Qun; Sun, Bo

    2012-04-01

    Sea ice in the Arctic Ocean plays an important role in the global climate change, and its quick change and impact are the scientists' focus all over the world. The spectra of different kinds of sea ice were measured with portable ASD FieldSpec 3 spectrometer during the long-term ice station of the 4th Chinese national Arctic Expedition in 2010, and the spectral features were analyzed systematically. The results indicated that the reflectance of sea ice covered by snow is the highest one, naked sea ice the second, and melted sea ice the lowest. Peak and valley characteristics of spectrum curves of sea ice covered by thick snow, thin snow, wet snow and snow crystal are very significant, and the reflectance basically decreases with the wavelength increasing. The rules of reflectance change with wavelength of natural sea ice, white ice and blue ice are basically same, the reflectance of them is medium, and that of grey ice is far lower than natural sea ice, white ice and blue ice. It is very significant for scientific research to analyze the spectral features of sea ice in the Arctic Ocean and to implement the quantitative remote sensing of sea ice, and to further analyze its response to the global warming. PMID:22715789

  17. Operational satellites and the global monitoring of snow and ice

    NASA Technical Reports Server (NTRS)

    Walsh, John E.

    1991-01-01

    The altitudinal dependence of the global warming projected by global climate models is at least partially attributable to the albedo-temperature feedback involving snow and ice, which must be regarded as key variables in the monitoring for global change. Statistical analyses of data from IR and microwave sensors monitoring the areal coverage and extent of sea ice have led to mixed conclusions about recent trends of hemisphere sea ice coverage. Seasonal snow cover has been mapped for over 20 years by NOAA/NESDIS on the basis of imagery from a variety of satellite sensors. Multichannel passive microwave data show some promise for the routine monitoring of snow depth over unforested land areas.

  18. Snow and Ice Products from the Aqua, Terra, and ICESat Satellites at the National Snow and Ice Data Center

    NASA Astrophysics Data System (ADS)

    Meier, W. N.; Marquis, M.; Kaminski, M.; Armstrong, R.; Brodzik, M.

    2004-05-01

    The National Snow and Ice Data Center (NSIDC) at the University of Colorado, Boulder - one of eight NASA Distributed Active Archive Centers (DAACs) - archives and distributes several products from sensors on the suite of NASA Earth Observing System (EOS) satellites. These include the sun-synchronous polar-orbiting Aqua (launched 4 May 2002) and Terra (launched 18 December 1999) platforms and the Ice, Cloud, and land Elevation Satellite (ICESat) (launched 12 January 2003). The Advanced Microwave Scanning Radiometer-EOS (AMSR-E) is a multi-channel passive microwave radiometer on Aqua (http://nsidc.org/daac/amsr/). AMSR-E Level 3 snow products are produced in EASE-Grid format for both the Northern and Southern Hemisphere and are available as daily, 5-day, and monthly fields. Daily AMSR-E Level 3 sea ice products are produced on a polar stereographic projection at gridded spatial resolutions of 6.25 km, 12.5 km and 25 km. Since April 2004, these products have been available for public distribution from NSIDC. The Moderate-resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua is a 36-channel visible/infrared sensor that produces a consistent long-term time series of fully-automated, quality-controlled data. Level 2 swath products are available for both snow cover and sea ice. Daily and 8-day Level 3 gridded snow cover products are available with estimates of snow extent and albedo at 500m resolution, along with daily Level 3 gridded sea ice products with estimates for sea ice extent and ice surface temperature at 1 km resolution. These products are currently available from NSIDC (http://nsidc.org/daac/modis/). The Geoscience Laser Altimeter System (GLAS) is the sole instrument on ICESat. The standard GLAS Level 2 ice sheet altimetry product contains the ice sheet elevation and elevation distribution calculated from algorithms fine-tuned for ice sheet returns. The standard GLAS Level 2 sea ice altimetry product contains the sea ice freeboard and sea ice roughness calculated from algorithms fine-tuned for sea ice returns. Both products also include the laser footprint geolocation, reflectance, and the geodetic, instrument, and atmospheric corrections used to correct the range measurements. An 8-day sample of these products has been available to the public (http://nsidc.org/daac/glas/) since October 2003. Improved versions, covering additional dates, have continued to be released since March 2004. In addition to the standard snow and ice products distributed by the data center, NSIDC scientists are also developing a variety of experimental products. One such product combines snow extent data from MODIS visible bands with snow water equivalent data from AMSR-E to improve snow cover estimates. Another product under investigation at NSIDC is a sea ice motion product derived from AMSR-E brightness temperature fields using cross-correlation feature matching techniques. These EOS sensors substantially enhance our ability to observe the cryosphere. GLAS represent an entirely new type of sensor for the cryosphere, while AMSR-E and MODIS offer significant improvements over the previous generation of sensors. The products from these sensors are a valuable resource for the investigation of regional and global climate issues and should yield new insights into the cryospheric system.

  19. 2013 Arctic Sea Ice Minimum - Duration: 27 seconds.

    NASA Video Gallery

    After an unusually cold summer in the northernmost latitudes, Arctic sea ice appears to have reached its annual minimum summer extent for 2013 on Sept. 13, the NASA-supported National Snow and Ice ...

  20. 9 The Dynamics of Snow and Ice Masses J.S. Wettlaufer

    E-print Network

    Wettlaufer, John S.

    principally because of their role in global warming and ice-age events. It is in this sense that ice9 The Dynamics of Snow and Ice Masses J.S. Wettlaufer Applied Physics Laboratory and Department of Physics, University of Washington, Seattle, WA 98105-5640, USA 9.1 Ice: Land, Sea and Air On Earth today

  1. Sea Ice Ecosystems

    NASA Astrophysics Data System (ADS)

    Arrigo, Kevin R.

    2014-01-01

    Polar sea ice is one of the largest ecosystems on Earth. The liquid brine fraction of the ice matrix is home to a diverse array of organisms, ranging from tiny archaea to larger fish and invertebrates. These organisms can tolerate high brine salinity and low temperature but do best when conditions are milder. Thriving ice algal communities, generally dominated by diatoms, live at the ice/water interface and in recently flooded surface and interior layers, especially during spring, when temperatures begin to rise. Although protists dominate the sea ice biomass, heterotrophic bacteria are also abundant. The sea ice ecosystem provides food for a host of animals, with crustaceans being the most conspicuous. Uneaten organic matter from the ice sinks through the water column and feeds benthic ecosystems. As sea ice extent declines, ice algae likely contribute a shrinking fraction of the total amount of organic matter produced in polar waters.

  2. An optical model for the microwave properties of sea ice

    NASA Technical Reports Server (NTRS)

    Gloersen, P.; Larabee, J. K.

    1981-01-01

    The complex refractive index of sea ice is modeled and used to predict the microwave signatures of various sea ice types. Results are shown to correspond well with the observed values of the complex index inferred from dielectic constant and dielectric loss measurements performed in the field, and with observed microwave signatures of sea ice. The success of this modeling procedure vis a vis modeling of the dielectric properties of sea ice constituents used earlier by several others is explained. Multiple layer radiative transfer calculations are used to predict the microwave properties of first-year sea ice with and without snow, and multiyear sea ice.

  3. Snow and ice ecosystems: not so extreme.

    PubMed

    Maccario, Lorrie; Sanguino, Laura; Vogel, Timothy M; Larose, Catherine

    2015-12-01

    Snow and ice environments cover up to 21% of the Earth's surface. They have been regarded as extreme environments because of their low temperatures, high UV irradiation, low nutrients and low water availability, and thus, their microbial activity has not been considered relevant from a global microbial ecology viewpoint. In this review, we focus on why snow and ice habitats might not be extreme from a microbiological perspective. Microorganisms interact closely with the abiotic conditions imposed by snow and ice habitats by having diverse adaptations, that include genetic resistance mechanisms, to different types of stresses in addition to inhabiting various niches where these potential stresses might be reduced. The microbial communities inhabiting snow and ice are not only abundant and taxonomically diverse, but complex in terms of their interactions. Altogether, snow and ice seem to be true ecosystems with a role in global biogeochemical cycles that has likely been underestimated. Future work should expand past resistance studies to understanding the function of these ecosystems. PMID:26408452

  4. Modelling and measuring the spectral bidirectional reflectance factor of snow-covered sea ice: an intercomparison study

    NASA Astrophysics Data System (ADS)

    Li, Shusun; Zhou, Xiaobing

    2004-12-01

    Broadband albedo is a very important geophysical parameter in the Earth surface-atmosphere interaction in either global climate change or hydrological cycle and snowmelt runoff studies. To derive the broadband albedo accurately from satellite optical sensor observation at limited bands and at a single observation angle, the bidirectional reflectance factor (BRF) has to be specified quantitatively. In the present albedo derivation algorithms from the satellite radiance data, the BRF is either modelled or observed. Questions may arise as to how well a BRF model can be in the broadband albedo derivation. To help answer such questions, we studied the performance of a snow-surface BRF model for two specific cases under large solar zenith angles (65° and 85°). We measured snow-surface spectral directional reflectance under clear skies. The snow physical properties, such as snow grain size and snow density, at the same sites were also measured. In situ snow physical data are used to simulate the snow-surface BRF and hemispherical directional reflectance factor (HDRF) through a multilayered azimuth- and zenith-dependent plane-parallel radiative transfer model. The field measurements and BRF and HDRF simulations all reveal the forward-scattering nature of snow surface under large solar incidence angles, but the BRF model results depict the strongest forward-scattering patterns under such solar zenith angles. Because the HDRF is simulated through coupling of the surface BRF with radiative transfer in the atmosphere, the resulting HDRF patterns agree with the field measurements better than the simulated BRF does. The deviation of the simulated HDRF from field-based clear-sky directional reflectance (FCDR) is within +/-10% for the central (viewing zenith angle <45° ) and lateral sides of the viewing hemisphere. This level of agreement between the simulated HDRF and FCDR also implies that the simulated BRF model can provide remote-sensing estimates of spectral albedo with an uncertainty of +/-10% for the same part of the viewing hemisphere. Further improvement in BRF model performance requires better handling of single scattering properties of snow grains, surface roughness, and atmospheric correction. Also, better procedures and techniques in field measurement are necessary for more accurate assessment of the performance of BRF models. Copyright

  5. First Moderate Resolution Imaging Spectroradiometer (MODIS) Snow and Ice Workshop

    NASA Technical Reports Server (NTRS)

    Hall, Dorothy K. (Editor)

    1995-01-01

    This document is a compilation of summaries of talks presented at a 2-day workshop on Moderate Resolution maging Spectroradiometer (MODIS) snow and ice products. The objectives of the workshop were to: inform the snow and ce community of potential MODIS products, seek advice from the participants regarding the utility of the products, and letermine the needs for future post-launch MODIS snow and ice products. Four working groups were formed to discuss at-launch snow products, at-launch ice products, post-launch snow and ice products and utility of MODIS snow and ice products, respectively. Each working group presented recommendations at the conclusion of the workshop.

  6. Remote sensing of snow and ice: A review of the research in the United States 1975 - 1978

    NASA Technical Reports Server (NTRS)

    Rango, A.

    1979-01-01

    Research work in the United States from 1975-1978 in the field of remote sensing of snow and ice is reviewed. Topics covered include snowcover mapping, snowmelt runoff forecasting, demonstration projects, snow water equivalent and free water content determination, glaciers, river and lake ice, and sea ice. A bibliography of 200 references is included.

  7. Commercial & Residential Property Maintenance Snow & Ice Control Members of

    E-print Network

    Isaacs, Rufus

    Commercial & Residential · Property Maintenance · Snow & Ice Control Members of: MGIA, Michigan Green Industry Association SIMA, Snow and Ice Management Association Lawn & Maintenance Team Member (248 & drug screening Self-motivated & good interpersonal skills Responsibilities Include: Perform lawn

  8. Record Arctic Sea Ice Loss in 2007

    NASA Technical Reports Server (NTRS)

    2007-01-01

    This image of the Arctic was produced from sea ice observations collected by the Advanced Microwave Scanning Radiometer (AMSR-E) Instrument on NASA's Aqua satellite on September 16, overlaid on the NASA Blue Marble. The image captures ice conditions at the end of the melt season. Sea ice (white, image center) stretches across the Arctic Ocean from Greenland to Russia, but large areas of open water were apparent as well. In addition to record melt, the summer of 2007 brought an ice-free opening though the Northwest Passage that lasted several weeks. The Northeast Passage did not open during the summer of 2007, however, as a substantial tongue of ice remained in place north of the Russian coast. According to the National Snow and Ice Data Center (NSIDC), on September 16, 2007, sea ice extent dropped to 4.13 million square kilometers (1.59 million square miles)--38 percent below average and 24 percent below the 2005 record.

  9. EOS Aqua AMSR-E Arctic Sea Ice Validation Program

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Markus, T.; Gasiewski, A.; Klein, M.; Maslanik, J.; Sturm, M.; Stroeve, J.; Heinrichs, J.

    2004-01-01

    A coordinated Arctic sea ice validation field campaign using the NASA Wallops P-3B aircraft was successfully completed in March 2003. This campaign was part of the program for validating the Earth Observing System (EOS) Aqua Advanced Microwave Scanning Radiometer (AMSR-E) sea ice products. The AMSR-E, designed and built by the Japanese National Space Development Agency for NASA, was launched May 4,2002 on the EOS Aqua spacecraft. The AMSR-E sea ice products include sea ice concentration, sea ice temperature, and snow depth on sea ice. The primary instrument on the P-3B aircraft was the NOAA ETL Polarimetric Scanning Radiometer (PSR) covering the same frequencies and polarizations as the AMSR-E. This paper describes the objectives of each of the seven flights, the Arctic regions overflown, and the coordination among satellite, aircraft, and surface-based measurements. Two of the seven aircraft flights were coordinated with scientists making surface measurements of snow and ice properties including sea ice temperature and snow depth on sea ice at a study area near Barrow, AK and at a Navy ice camp located in the Beaufort Sea. The remaining flights covered portions of the Bering Sea ice edge, the Chukchi Sea, and Norton Sound. Comparisons among the satellite and aircraft PSR data sets are presented.

  10. 14 CFR 139.313 - Snow and ice control.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Snow and ice control. 139.313 Section...OF AIRPORTS Operations § 139.313 Snow and ice control. (a) As determined...certificate holder whose airport is located where snow and icing conditions occur must...

  11. 14 CFR 139.313 - Snow and ice control.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Snow and ice control. 139.313 Section...OF AIRPORTS Operations § 139.313 Snow and ice control. (a) As determined...certificate holder whose airport is located where snow and icing conditions occur must...

  12. 14 CFR 139.313 - Snow and ice control.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Snow and ice control. 139.313 Section...OF AIRPORTS Operations § 139.313 Snow and ice control. (a) As determined...certificate holder whose airport is located where snow and icing conditions occur must...

  13. 14 CFR 139.313 - Snow and ice control.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Snow and ice control. 139.313 Section...OF AIRPORTS Operations § 139.313 Snow and ice control. (a) As determined...certificate holder whose airport is located where snow and icing conditions occur must...

  14. 14 CFR 139.313 - Snow and ice control.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Snow and ice control. 139.313 Section...OF AIRPORTS Operations § 139.313 Snow and ice control. (a) As determined...certificate holder whose airport is located where snow and icing conditions occur must...

  15. 14 CFR 139.313 - Snow and ice control.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Snow and ice control. 139.313 Section 139... AIRPORTS Operations § 139.313 Snow and ice control. (a) As determined by the Administrator, each certificate holder whose airport is located where snow and icing conditions occur must prepare, maintain,...

  16. 14 CFR 139.313 - Snow and ice control.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Snow and ice control. 139.313 Section 139... AIRPORTS Operations § 139.313 Snow and ice control. (a) As determined by the Administrator, each certificate holder whose airport is located where snow and icing conditions occur must prepare, maintain,...

  17. 14 CFR 139.313 - Snow and ice control.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Snow and ice control. 139.313 Section 139... AIRPORTS Operations § 139.313 Snow and ice control. (a) As determined by the Administrator, each certificate holder whose airport is located where snow and icing conditions occur must prepare, maintain,...

  18. 14 CFR 139.313 - Snow and ice control.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Snow and ice control. 139.313 Section 139... AIRPORTS Operations § 139.313 Snow and ice control. (a) As determined by the Administrator, each certificate holder whose airport is located where snow and icing conditions occur must prepare, maintain,...

  19. 14 CFR 139.313 - Snow and ice control.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Snow and ice control. 139.313 Section 139... AIRPORTS Operations § 139.313 Snow and ice control. (a) As determined by the Administrator, each certificate holder whose airport is located where snow and icing conditions occur must prepare, maintain,...

  20. Diatom vertical migration within land-fast Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Aumack, C. F.; Juhl, A. R.; Krembs, C.

    2014-11-01

    Light levels inside first-year, landfast sea ice were experimentally altered by manipulating overlying snow depths. Irradiance available for ice algae growing near the ice-bottom, and under the ice, was highly dependent on snow depths ranging from 0 to > 30 cm. Importantly, algal vertical distributions also changed under different irradiances. Under thick snow (low light), the majority of algae were found several cm above the ice-seawater interface, while progressively more were found nearer the interface at locations with thinner overlying snow (higher light). Short-term field experiments suggested that ice algae were able to reposition themselves within the ice column within 3 days after manipulating snow depths. Laboratory gliding rate measurements of a cultured ice diatom suggested that it is capable of daily cm-scale movement. Vertical migration may help ice diatoms balance opposing light and nutrient resource gradients, similar to strategies used by some benthic and pelagic algae. Moreover, when ice algae congregate near the ice-seawater interface, they may be especially susceptible to loss from the ice environment. Vertical repositioning in response to changing light dynamics may be a mechanism to optimize between vertically-opposing environmental factors and help explain the connection between melting snow cover and export of biomass from sea ice.

  1. Surface-based passive microwave observations of sea ice in the Bering and Greenland Seas

    NASA Technical Reports Server (NTRS)

    Grenfell, T. C.

    1986-01-01

    Brightness temperatures of sea ice was measured during the Marginal Ice Zone Experiment (MIZEX) field experiments in February in the Bering Sea and in June/July in the northern Greenland Sea. In the Bering Sea thin growing sea ice types from black ice to 40 cm thick snow covered floes were investigated. Brightness temperatures increase with ice thickness up to 10 cm from values of 100 K for open water to as high as 250 K (e = 0.97) for thick ice, and a moderate dependence on snow thickness is found. In the Greenland Sea thick first and multiyear (FY, MY) ice types were studied. Brightness temperatures vary, depending on the daily melt-freeze cycle superimposed on the seasonal warming, ranging from near blackbody values for melting conditions to multiyear-like spectra when the surface layers refroze. The melt season was sufficiently advanced, however, that FY and MY ice could not be differentiated radiometrically.

  2. Record Sea Ice Minimum

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Arctic sea ice reached a record low in September 2007, below the previous record set in 2005 and substantially below the long-term average. This image shows the Arctic as observed by the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) aboard NASA's Aqua satellite on September 16, 2007. In this image, blue indicates open water, white indicates high sea ice concentration, and turquoise indicates loosely packed sea ice. The black circle at the North Pole results from an absence of data as the satellite does not make observations that far north. Three contour lines appear on this image. The red line is the 2007 minimum, as of September 15, about the same time the record low was reached, and it almost exactly fits the sea ice observed by AMSR-E. The green line indicates the 2005 minimum, the previous record low. The yellow line indicates the median minimum from 1979 to 2000.

  3. Airborne Spectral Measurements of Surface-Atmosphere Anisotropy for Arctic Sea Ice and Tundra

    NASA Technical Reports Server (NTRS)

    Arnold, G. Thomas; Tsay, Si-Chee; King, Michael D.; Li, Jason Y.; Soulen, Peter F.

    1999-01-01

    Angular distributions of spectral reflectance for four common arctic surfaces: snow-covered sea ice, melt-season sea ice, snow-covered tundra, and tundra shortly after snowmelt were measured using an aircraft based, high angular resolution (1-degree) multispectral radiometer. Results indicate bidirectional reflectance is higher for snow-covered sea ice than melt-season sea ice at all wavelengths between 0.47 and 2.3 pm, with the difference increasing with wavelength. Bidirectional reflectance of snow-covered tundra is higher than for snow-free tundra for measurements less than 1.64 pm, with the difference decreasing with wavelength. Bidirectional reflectance patterns of all measured surfaces show maximum reflectance in the forward scattering direction of the principal plane, with identifiable specular reflection for the melt-season sea ice and snow-free tundra cases. The snow-free tundra had the most significant backscatter, and the melt-season sea ice the least. For sea ice, bidirectional reflectance changes due to snowmelt were more significant than differences among the different types of melt-season sea ice. Also the spectral-hemispherical (plane) albedo of each measured arctic surface was computed. Comparing measured nadir reflectance to albedo for sea ice and snow-covered tundra shows albedo underestimated 5-40%, with the largest bias at wavelengths beyond 1 pm. For snow-free tundra, nadir reflectance underestimates plane albedo by about 30-50%.

  4. Seasonal evolution of melt ponds on Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Webster, Melinda A.; Rigor, Ignatius G.; Perovich, Donald K.; Richter-Menge, Jacqueline A.; Polashenski, Christopher M.; Light, Bonnie

    2015-09-01

    The seasonal evolution of melt ponds has been well documented on multiyear and landfast first-year sea ice, but is critically lacking on drifting, first-year sea ice, which is becoming increasingly prevalent in the Arctic. Using 1 m resolution panchromatic satellite imagery paired with airborne and in situ data, we evaluated melt pond evolution for an entire melt season on drifting first-year and multiyear sea ice near the 2011 Applied Physics Laboratory Ice Station (APLIS) site in the Beaufort and Chukchi seas. A new algorithm was developed to classify the imagery into sea ice, thin ice, melt pond, and open water classes on two contrasting ice types: first-year and multiyear sea ice. Surprisingly, melt ponds formed ˜3 weeks earlier on multiyear ice. Both ice types had comparable mean snow depths, but multiyear ice had 0-5 cm deep snow covering ˜37% of its surveyed area, which may have facilitated earlier melt due to its low surface albedo compared to thicker snow. Maximum pond fractions were 53 ± 3% and 38 ± 3% on first-year and multiyear ice, respectively. APLIS pond fractions were compared with those from the Surface Heat Budget of the Arctic Ocean (SHEBA) field campaign. APLIS exhibited earlier melt and double the maximum pond fraction, which was in part due to the greater presence of thin snow and first-year ice at APLIS. These results reveal considerable differences in pond formation between ice types, and underscore the importance of snow depth distributions in the timing and progression of melt pond formation.

  5. 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.

  6. The future of water, ice, snow underThe future of water, ice, snow under global warmingglobal warming

    E-print Network

    and fire water's chemistrywater's chemistry ice and the polar worldice and the polar world water wars: water as an innate rightwater wars: water as an innate right #12;VP Al Gore'sVP Al Gore's InconvenientThe future of water, ice, snow underThe future of water, ice, snow under global warmingglobal

  7. Seafloor Control on Sea Ice

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Clemente-Colon, P.; Rigor, I. G.; Hall, D. K.; Neumann, G.

    2011-01-01

    The seafloor has a profound role in Arctic sea ice formation and seasonal evolution. Ocean bathymetry controls the distribution and mixing of warm and cold waters, which may originate from different sources, thereby dictating the pattern of sea ice on the ocean surface. Sea ice dynamics, forced by surface winds, are also guided by seafloor features in preferential directions. Here, satellite mapping of sea ice together with buoy measurements are used to reveal the bathymetric control on sea ice growth and dynamics. Bathymetric effects on sea ice formation are clearly observed in the conformation between sea ice patterns and bathymetric characteristics in the peripheral seas. Beyond local features, bathymetric control appears over extensive ice-prone regions across the Arctic Ocean. The large-scale conformation between bathymetry and patterns of different synoptic sea ice classes, including seasonal and perennial sea ice, is identified. An implication of the bathymetric influence is that the maximum extent of the total sea ice cover is relatively stable, as observed by scatterometer data in the decade of the 2000s, while the minimum ice extent has decreased drastically. Because of the geologic control, the sea ice cover can expand only as far as it reaches the seashore, the continental shelf break, or other pronounced bathymetric features in the peripheral seas. Since the seafloor does not change significantly for decades or centuries, sea ice patterns can be recurrent around certain bathymetric features, which, once identified, may help improve short-term forecast and seasonal outlook of the sea ice cover. Moreover, the seafloor can indirectly influence cloud cover by its control on sea ice distribution, which differentially modulates the latent heat flux through ice covered and open water areas.

  8. Surface Albedo of the Antarctic Sea Ice Zone RICHARD E. BRANDT AND STEPHEN G. WARREN

    E-print Network

    Warren, Stephen

    water, grease ice, nilas, young "grey" ice, young grey-white ice, and first-year ice, both vary from 0.07 for open water to 0.87 for thick snow-covered ice under cloud. The frequency-averaged albedo is the fraction of open water within the pack. 1. Introduction Antarctic sea ice appears

  9. Characterizing sea ice surface morphology using high-resolution IceBridge data

    NASA Astrophysics Data System (ADS)

    Petty, A.; Farrell, S. L.; Newman, T.; Kurtz, N. T.; Richter-Menge, J.; Tsamados, M.; Feltham, D. L.

    2014-12-01

    Sea ice pressure ridges form when ice floes collide while drifting under the combined forces of atmospheric drag, oceanic drag and ice-ice interaction. Sea ice ridges, in-turn, affect the resultant form drag on the sea ice cover and thus impact the fluxes of momentum and heat between the atmosphere and ocean. Here we present initial results of a new sea ice ridge detection approach that utilizes high resolution, three-dimensional ice/snow surface elevation data from the NASA Operation IceBridge Airborne Topographic Mapper (ATM) laser altimeter merged with coincident high-resolution imagery from the Digital Mapping System (DMS). We derive novel information regarding sea ice deformation across a variety of ice types and regimes. Statistical information regarding sea ice ridges (height/frequency/orientation) and floe edges (freeboard height) are presented for several IceBridge flight lines. These novel characterizations of sea ice surface morphology will be used to validate and inform drag parameterizations in state-of-the-art sea ice models. Furthermore, they will advance our ability to quantify uncertainties introduced by pressure ridges in the estimation of sea ice freeboard/thickness from airborne and satellite altimeters.

  10. Characterizing sea ice surface morphology using high-resolution IceBridge data

    NASA Astrophysics Data System (ADS)

    Petty, Alek; Farrell, Sinead; Newman, Thomas; Kurtz, Nathan; Richter-Menge, Jacqueline; Tsamados, Michel; Feltham, Daniel

    2015-04-01

    Sea ice pressure ridges form when ice floes collide while drifting under the combined forces of atmospheric drag, oceanic drag and ice-ice interaction. Sea ice ridges, in-turn, affect the resultant form drag on the sea ice cover and thus impact the fluxes of momentum and heat between the atmosphere and ocean. Here we present initial results of a new sea ice ridge detection approach that utilizes high resolution, three-dimensional ice/snow surface elevation data from the NASA Operation IceBridge Airborne Topographic Mapper (ATM) laser altimeter merged with coincident high-resolution imagery from the Digital Mapping System (DMS). We derive novel information regarding sea ice deformation across a variety of ice types and regimes. Statistical information regarding sea ice ridges (height/frequency/orientation) and floe edges (freeboard height) are presented for several IceBridge flight lines. These novel characterizations of sea ice surface morphology will be used to validate and inform drag parameterizations in state-of-the-art sea ice models. Furthermore, they will advance our ability to quantify uncertainties introduced by pressure ridges in the estimation of sea ice freeboard/thickness from airborne and satellite altimeters.

  11. The Importance of Snow and Ice Surface Roughness in Ablation Processes

    NASA Astrophysics Data System (ADS)

    Herzfeld, U. C.; Box, J. E.; Steffen, K.; Mayer, H.; Caine, N.; Losleben, M. V.

    2002-12-01

    The influence of surface roughness of snow and ice on melt energy has been greatly underestimated to date. Surface roughness has usually been included in climatological, meteorological, and snow-hydrological models as a one-dimensional parameter, roughness length, than has been estimated rather than measured. We define surface roughness as a spatial variable and measure it with the Glacier Roughness Sensor (GRS). GRS data from a part of the ablation area in the Greenland Ice Sheet (ice surfaces) and from a continental alpine environment (snow surfaces) are analyzed using geostatistical classification. A mathematical relationship between aerodynamic roughness length and spatial surface roughness is developed. Using this relationship, roughness length of a range of snow and ice surfaces is calculated from the GRS measurements, and the resultant values are input in energy balance calculations. As a result, melt energy varies by a factor of two or more dependent on surface roughness. Consequently, it is important to measure snow and ice surface roughness and include it more accurately in climatological, meteorological, and snow-hydrological models. Applications are the assessment of ablation and surface processes on glaciers and ice sheets in general, and in response to global warming in particular, resultant changes in sea level, study of changes in alpine glaciers and snowfields, and modeling of snow-hydrological processes.

  12. Beyond Point Measurements: Sea Ice Floes Characterized in 3-D

    NASA Astrophysics Data System (ADS)

    Williams, Guy D.; Maksym, Ted; Kunz, Clayton; Kimball, Peter; Singh, Hanumant; Wilkinson, Jeremy; Lachlan-Cope, Tom; Trujillo, Ernesto; Steer, Adam; Massom, Rob; Meiners, Klaus; Heil, Petra; Lieser, Jan; Leonard, Katherine

    2013-02-01

    A new methodology for coincident floe-scale measurements of the surface elevation, snow depth, and ice draft (the thickness below the water line) of Antarctic sea ice has been demonstrated during two recent research voyages: the Australian-led Sea Ice Physics and Ecosystem Experiment II (SIPEX II) to East Antarctica in September-November 2012 and the United Kingdom-led Ice Mass Balance in the Bellingshausen Sea (ICEBell) voyage to the Weddell and Bellingshausen Seas in November 2010 (Figure 1a).

  13. Arctic Sea ice model sensitivities.

    SciTech Connect

    Peterson, Kara J.; Bochev, Pavel Blagoveston; Paskaleva, Biliana Stefanova

    2010-12-01

    Arctic sea ice is an important component of the global climate system and, due to feedback effects, the Arctic ice cover is changing rapidly. Predictive mathematical models are of paramount importance for accurate estimates of the future ice trajectory. However, the sea ice components of Global Climate Models (GCMs) vary significantly in their prediction of the future state of Arctic sea ice and have generally underestimated the rate of decline in minimum sea ice extent seen over the past thirty years. One of the contributing factors to this variability is the sensitivity of the sea ice state to internal model parameters. A new sea ice model that holds some promise for improving sea ice predictions incorporates an anisotropic elastic-decohesive rheology and dynamics solved using the material-point method (MPM), which combines Lagrangian particles for advection with a background grid for gradient computations. We evaluate the variability of this MPM sea ice code and compare it with the Los Alamos National Laboratory CICE code for a single year simulation of the Arctic basin using consistent ocean and atmospheric forcing. Sensitivities of ice volume, ice area, ice extent, root mean square (RMS) ice speed, central Arctic ice thickness,and central Arctic ice speed with respect to ten different dynamic and thermodynamic parameters are evaluated both individually and in combination using the Design Analysis Kit for Optimization and Terascale Applications (DAKOTA). We find similar responses for the two codes and some interesting seasonal variability in the strength of the parameters on the solution.

  14. Amundsen Sea sea-ice variability, atmospheric circulation, and spatial variations in snow isotopic composition from new West Antarctic firn cores

    E-print Network

    Criscitiello, Alison Sara

    2014-01-01

    Recent work has documented dramatic changes in the West Antarctic Ice Sheet (WAIS) over the past 30 years (e.g., mass loss, glacier acceleration, surface warming) due largely to the influence of the marine environment. ...

  15. Sea Ice Radiative Forcing, Sea Ice Area, and Climate Sensitivity

    NASA Astrophysics Data System (ADS)

    Caldeira, K.; Cvijanovic, I.

    2014-12-01

    Changes in sea ice cover affect climate sensitivity by modifying albedo and surface heat flux exchange, which in turn affect the absorbed solar radiation at the surface as well as cloud cover, atmospheric water content and poleward atmospheric heat transport. Here, we use a configuration of the Community Earth System Model 1.0.4 with a slab ocean model and a thermodynamic-dynamic sea ice model to investigate the overall net effect of feedbacks associated with the sea ice loss. We analyze the strength of the overall sea ice feedback in terms of two factors: the sensitivity of sea ice area to changes in temperature, and the sensitivity of sea ice radiative forcing to changes in sea ice area. In this model configuration, sea ice area decreases by ~3 × 1012 m2 per K of global warming, while the effective global radiative forcing per unit area of sea ice loss is ~0.1 × 10-12 W m-2. The product of these two terms (~0.3 W m-2 K-1) approximately equals the difference in climate feedback parameter found in simulations with sea ice response (1.05 W m-2 K-1) and simulations without sea ice response (1.31 W m-2 K-1 or 1.35 W m-2 K-1, depending on the method used to disable the changes in sea ice cover). Thus, we find that in our model simulations, sea ice response accounts for about 20% to 22% of the climate sensitivity to an imposed change in radiative forcing. In our model, the additional radiative forcing resulting from a loss of all sea-ice in the "pre-industrial" state is comparable to but somewhat less than the radiative forcing from a doubling of atmospheric CO2 content.

  16. A continuum model of melt pond evolution on Arctic sea ice Daniela Flocco1

    E-print Network

    Feltham, Daniel

    A continuum model of melt pond evolution on Arctic sea ice Daniela Flocco1 and Daniel L. Feltham1 the Northern Hemisphere summer, absorbed solar radiation melts snow and the upper surface of Arctic sea ice to generate meltwater that accumulates in ponds. The melt ponds reduce the albedo of the sea ice cover during

  17. Sea Ice and Oceanographic Conditions.

    ERIC Educational Resources Information Center

    Oceanus, 1986

    1986-01-01

    The coastal waters of the Beaufort Sea are covered with ice three-fourths of the year. These waters (during winter) are discussed by considering: consolidation of coastal ice; under-ice water; brine circulation; biological energy; life under the ice (including kelp and larger animals); food chains; and ice break-up. (JN)

  18. Commercial & Residential Property Maintenance Snow & Ice Control Members of

    E-print Network

    Isaacs, Rufus

    Commercial & Residential Property Maintenance Snow & Ice Control Members of: MGIA, Michigan Green Industry Association SIMA, Snow and Ice Management Association For Us, Business is Personal Your Way record and DOT Medical Card. Ability to drive a truck with a trailer Clear background check and drug

  19. Commercial & Residential Property Maintenance Snow & Ice Control Members of

    E-print Network

    Isaacs, Rufus

    Commercial & Residential · Property Maintenance · Snow & Ice Control Members of: MGIA, Michigan Green Industry Association SIMA, Snow and Ice Management Association Landscape Foreman (248) 676 with a trailer Ability to run a skid steer and various forms of equipment Clear background check & drug

  20. Remote sensing as a research tool. [sea ice surveillance from aircraft and spacecraft

    NASA Technical Reports Server (NTRS)

    Carsey, F. D.; Zwally, H. J.

    1986-01-01

    The application of aircraft and spacecraft remote sensing techniques to sea ice surveillance is evaluated. The effects of ice in the air-sea-ice system are examined. The measurement principles and characteristics of remote sensing methods for aircraft and spacecraft surveillance of sea ice are described. Consideration is given to ambient visible light, IR, passive microwave, active microwave, and laser altimeter and sonar systems. The applications of these systems to sea ice surveillance are discussed and examples are provided. Particular attention is placed on the use of microwave data and the relation between ice thickness and sea ice interactions. It is noted that spacecraft and aircraft sensing techniques can successfully measure snow cover; ice thickness; ice type; ice concentration; ice velocity field; ocean temperature; surface wind vector field; and air, snow, and ice surface temperatures.

  1. West Antarctica snow accumulation trend study (1979-2011) from Snow Radar and ice core profiles

    E-print Network

    Feng, Boyu

    2014-12-31

    periods to be determined. The focus is on one particular ice penetrating radar system: Snow Radar from the Center for Remote Sensing of Ice Sheet (CReSIS). The Snow Radar is a 2-8 GHz ultra-wideband (UWB), frequency-modulated, continuous-wave (FMCW) radar...

  2. Interannual Variability of Snow and Ice and Impact on the Carbon Cycle

    NASA Technical Reports Server (NTRS)

    Yung, Yuk L.

    2004-01-01

    The goal of this research is to assess the impact of the interannual variability in snow/ice using global satellite data sets acquired in the last two decades. This variability will be used as input to simulate the CO2 interannual variability at high latitudes using a biospheric model. The progress in the past few years is summarized as follows: 1) Albedo decrease related to spring snow retreat; 2) Observed effects of interannual summertime sea ice variations on the polar reflectance; 3) The Northern Annular Mode response to Arctic sea ice loss and the sensitivity of troposphere-stratosphere interaction; 4) The effect of Arctic warming and sea ice loss on the growing season in northern terrestrial ecosystem.

  3. Halogen-based reconstruction of Russian Arctic sea ice area from the Akademii Nauk ice core (Severnaya Zemlya)

    NASA Astrophysics Data System (ADS)

    Spolaor, A.; Opel, T.; McConnell, J. R.; Maselli, O. J.; Spreen, G.; Varin, C.; Kirchgeorg, T.; Fritzsche, D.; Vallelonga, P.

    2015-08-01

    The role of sea ice in the Earth climate system is still under debate, although it is known to influence albedo, ocean circulation, and atmosphere-ocean heat and gas exchange. Here we present a reconstruction of AD 1950 to 1998 sea ice in the Laptev Sea based on the Akademii Nauk ice core (Severnaya Zemlya, Russian Arctic). The halogens bromine (Br) and iodine (I) are strongly influenced by sea ice processes. Bromine reacts with the sea ice surface in auto-catalyzing "Bromine explosion" events causing an enrichment of the Br / Na ratio and the bromine excess (Brexc) in snow compared to that in seawater. Iodine is emitted from algal communities growing under sea ice. The results suggest a connection between Brexc and spring sea ice area, as well as a connection between iodine concentration and summer sea ice area. These two halogens are therefore good candidates for extended reconstructions of past sea ice changes in the Arctic.

  4. Sea ice/climate studies

    NASA Technical Reports Server (NTRS)

    Parkinson, C. L.

    1988-01-01

    The objectives were to determine and analyze the annual cycle of sea ice extents in the Arctic Ocean and peripheral seas and bays over the period 1973 to 1986, looking in particular for any long term trends; to examine the relationship between local sea ice covers and the surrounding atmosphere and ocean; and to examine sea ice as a potential early indicator of climate change. The work involves creating regional and hemispheric time series of sea ice variables from satellite passive microwave data and analyzing these through various intercomparisons amongst themselves and with oceanographic and atmospheric fields.

  5. Sea ice and polar climate in the NCAR CSM

    SciTech Connect

    Weatherly, J.W.; Briegleb, B.P.; Large, W.G.; Maslanik, J.A.

    1998-06-01

    The Climate System Model (CSM) consists of atmosphere, ocean, land, and sea-ice components linked by a flux coupler, which computes fluxes of energy and momentum between components. The sea-ice component consists of a thermodynamic formulation for ice, snow, and leads within the ice pack, and ice dynamics using the cavitating-fluid ice rheology, which allows for the compressive strength of ice but ignores shear viscosity. The results of a 300-yr climate simulation are presented, with the focus on sea ice and the atmospheric forcing over sea ice in the polar regions. The atmospheric model results are compared to analyses from the European Centre for Medium-Range Weather Forecasts and other observational sources. The sea-ice concentrations and velocities are compared to satellite observational data. The atmospheric sea level pressure (SLP) in CSM exhibits a high in the central Arctic displaced poleward from the observed Beaufort high. The Southern Hemisphere SLP over sea ice is generally 5 mb lower than observed. Air temperatures over sea ice in both hemispheres exhibit cold biases of 2--4 K. The precipitation-minus-evaporation fields in both hemispheres are greatly improved over those from earlier versions of the atmospheric GCM.

  6. Polarimetric signatures of sea ice. 1: Theoretical model

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.

    1995-01-01

    Physical, structral, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarmetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies to interpretation of sea ice polarimetric signatures.

  7. Polarimetric Signatures of Sea Ice. Part 1; Theoretical Model

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.

    1995-01-01

    Physical, structural, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarimetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies for interpretation of sea ice polarimetric signatures.

  8. Modeling of Antarctic sea ice in a general circulation model

    SciTech Connect

    Wu, Xingren; Budd, W.F.; Simmonds, I.

    1997-04-01

    A dynamic-thermodynamic sea ice model is developed and coupled with the Melbourne University general circulation model to simulate the seasonal cycle of the Antarctic sea ice distributions The model is efficient, rapid to compute, and useful for a range of climate studies. The thermodynamic part of the sea ice model is similar to that developed by Parkinson and Washington, the dynamics contain a simplified ice rheology that resists compression. The thermodynamics is based on energy conservation at the top surface of the ice/snow, the ice/water interface, and the open water area to determine the ice formation, accretion, and ablation. A lead parameterization is introduced with an effective partitioning scheme for freezing between and under the ice floes. The dynamic calculation determines the motion of ice, which is forced with the atmospheric wind, taking account of ice resistance and rafting. The simulated sea ice distribution compares reasonably well with observations. The seasonal cycle of ice extent is well simulated in phase as well as in magnitude. Simulated sea ice thickness and concentration are also in good agreement with observations over most regions and serve to indicate the importance of advection and ocean drift in the determination of the sea ice distribution. 64 refs., 15 figs., 2 tabs.

  9. Thermodynamic sea ice growth in the central Weddell Sea, observed in upward-looking sonar data

    NASA Astrophysics Data System (ADS)

    Behrendt, A.; Dierking, W.; Witte, H.

    2015-03-01

    Upward-looking sonar (ULS) data were used to analyze thermodynamic sea ice growth. The study was carried out for an ocean region in the central Weddell Sea, for which data of sea ice thickness variability and of the oceanic heat flux through the ice are rare. In the study area the contribution of sea ice deformation to vertical ice growth is relatively small in some years. This provides the opportunity to simulate thermodynamic sea ice growth considering the influence of a snow cover and of the oceanic heat flux. To this end, a modified version of Stefan's law was used. The resulting ice thickness variations were then compared with the ULS measurements. For the investigated cases, the best consistency between data and model results was obtained assuming a snow layer of less than 5 cm thickness and average oceanic heat fluxes between 6 and 14 W m-2. It is demonstrated that in conjunction with ice drift data and analytical models for thermal sea ice growth, ULS ice thickness measurements are useful for studying the seasonal cycle of growth and decay and for inferring the magnitude of the average oceanic heat flux under sea ice.

  10. EOS Aqua AMSR-E Arctic Sea Ice Validation Program: Arctic2003 Aircraft Campaign Flight Report

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Markus,T.

    2003-01-01

    In March 2003 a coordinated Arctic sea ice validation field campaign using the NASA Wallops P-3B aircraft was successfully completed. This campaign was part of the program for validating the Earth Observing System (EOS) Aqua Advanced Microwave Scanning Radiometer (AMSR-E) sea ice products. The AMSR-E, designed and built by the Japanese National Space Development Agency for NASA, was launched May 4, 2002 on the EOS Aqua spacecraft. The AMSR-E sea ice products to be validated include sea ice concentration, sea ice temperature, and snow depth on sea ice. This flight report describes the suite of instruments flown on the P-3, the objectives of each of the seven flights, the Arctic regions overflown, and the coordination among satellite, aircraft, and surface-based measurements. Two of the seven aircraft flights were coordinated with scientists making surface measurements of snow and ice properties including sea ice temperature and snow depth on sea ice at a study area near Barrow, AK and at a Navy ice camp located in the Beaufort Sea. Two additional flights were dedicated to making heat and moisture flux measurements over the St. Lawrence Island polynya to support ongoing air-sea-ice processes studies of Arctic coastal polynyas. The remaining flights covered portions of the Bering Sea ice edge, the Chukchi Sea, and Norton Sound.

  11. Modeling the winter-spring transition of first-year ice in the western Weddell Sea

    NASA Astrophysics Data System (ADS)

    Jeffery, N.; Hunke, E. C.

    2014-09-01

    A new halodynamic scheme is coupled with the Los Alamos sea ice model to simulate western Weddell Sea ice during the winter-spring transition. One-dimensional temperature and salinity profiles are consistent with the warming and melt stages exhibited in first-year ice cores from the 2004 Ice Station POLarstern (ISPOL) expedition. Results are highly sensitive to snowfall. Simulations which use reanalysis precipitation data do not retain a snow cover beyond mid-December, and the warming transition occurs too rapidly. Model performance is greatly improved by prescribing a snowfall rate based on reported snow thicknesses. During ice growth prior to ISPOL, simulations indicate a period of thick snow and upper ice salinity enrichment. Gravity drainage model parameters impact the simulation immediately, while effects from the flushing parameter (snow porosity at the ice top) appear as the freeboard becomes negative. Simulations using a snow porosity of 0.3, consistent with that of wet snow, agree with salinity observations. The model does not include lateral sources of sea-water flooding, but vertical transport processes account for the high upper-ice salinities observed in ice cores at the start of the expedition. As the ice warms, a fresh upper-ice layer forms, and the high salinity layer migrates downward. This pattern is consistent with the early spring development stages of high-porosity layers observed in Antarctic sea ice that are associated with rich biological production. Future extensions of the model may be valuable in Antarctic ice-biogeochemical applications.

  12. NASA IceBridge: Airborne surveys of the polar sea ice covers

    NASA Astrophysics Data System (ADS)

    Richter-Menge, J.; Farrell, S. L.

    2014-12-01

    The NASA Operation IceBridge (OIB) airborne sea ice surveys are designed to continue a valuable series of sea ice thickness measurements by bridging the gap between NASA's Ice, Cloud and Land Elevation Satellite (ICESat), which operated from 2003 to 2009, and ICESat-2, which is scheduled for launch in 2017. Initiated in 2009, OIB has conducted campaigns over the western Arctic Ocean (March/April) and Southern Oceans (October/November) on an annual basis. Primary OIB sensors being used for sea ice observations include the Airborne Topographic Mapper laser altimeter, the Digital Mapping System digital camera, a Ku-band radar altimeter, a frequency-modulated continuous-wave (FMCW) snow radar, and a KT-19 infrared radiation pyrometer. Data from the campaigns are available to the research community at: http://nsidc.org/data/icebridge/. This presentation will summarize the spatial and temporal extent of the campaigns and highlight key scientific accomplishments, which include: • Documented changes in the Arctic marine cryosphere since the dramatic sea ice loss of 2007 • Novel snow depth measurements over sea ice in the Arctic • Improved skill of April-to-September sea ice predictions via numerical ice/ocean models • Validation of satellite altimetry measurements (ICESat, CryoSat-2, and IceSat-2/MABEL)

  13. Winter Ice and Snow as Models of Igneous Rock Formation.

    ERIC Educational Resources Information Center

    Romey, William D.

    1983-01-01

    Examines some features of ice and snow that offer teachers and researchers help in understanding many aspects of igneous processes and configurations. Careful observation of such processes as melting, decay, evolution, and snow accumulation provide important clues to understanding processes by which many kinds of rocks form. (Author/JN)

  14. Sea Ice on the Southern Ocean

    NASA Technical Reports Server (NTRS)

    Jacobs, Stanley S.

    1998-01-01

    Year-round satellite records of sea ice distribution now extend over more than two decades, providing a valuable tool to investigate related characteristics and circulations in the Southern Ocean. We have studied a variety of features indicative of oceanic and atmospheric interactions with Antarctic sea ice. In the Amundsen & Bellingshausen Seas, sea ice extent was found to have decreased by approximately 20% from 1973 through the early 1990's. This change coincided with and probably contributed to recently warmer surface conditions on the west side of the Antarctic Peninsula, where air temperatures have increased by approximately 0.5 C/decade since the mid-1940's. The sea ice decline included multiyear cycles of several years in length superimposed on high interannual variability. The retreat was strongest in summer, and would have lowered the regional mean ice thickness, with attendant impacts upon vertical heat flux and the formation of snow ice and brine. The cause of the regional warming and loss of sea ice is believed to be linked to large-scale circulation changes in the atmosphere and ocean. At the eastern end of the Weddell Gyre, the Cosmonaut Polyna revealed greater activity since 1986, a recurrence pattern during recent winters and two possible modes of formation. Persistence in polynya location was noted off Cape Ann, where the coastal current can interact more strongly with the Antarctic Circumpolar Current. As a result of vorticity conservation, locally enhanced upwelling brings warmer deep water into the mixed layer, causing divergence and melting. In the Ross Sea, ice extent fluctuates over periods of several years, with summer minima and winter maxima roughly in phase. This leads to large interannual cycles of sea ice range, which correlate positively with meridinal winds, regional air temperatures and subsequent shelf water salinities. Deep shelf waters display considerable interannual variability, but have freshened by approximately 0.03/decade since the late 1950's. That could have slowed the thermohaline circulation beneath the Ross Ice Shelf and the properties or volume of local bottom water production.

  15. Mapping of ice layer extent and snow accumulation in the percolation zone of the Greenland ice sheet

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    The Greenland ice sheet underwent record extensive melt in 2002 and prolonged melt in 2003. The severe melting created a significant and extensive ice layer over the Greenland ice sheet. An innovative approach is developed to detect the ice 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 ice layer formation. The results reveal areas of extensive ice layer formed by the 2002 melt, which is consistent with the maximum melt extent in 2002. Moreover, during freezing seasons, QuikSCAT data show a linear decrease in backscatter (in decibels or dB) that is related to the amount of snow accumulation in the ice 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 season.

  16. Snow and Ice Applications of AVHRR in Polar Regions: Report of a Workshop

    NASA Technical Reports Server (NTRS)

    Steffen, K.; Bindschadler, R.; Casassa, G.; Comiso, J.; Eppler, D.; Fetterer, F.; Hawkins, J.; Key, J.; Rothrock, D.; Thomas, R.; Weaver, R.; Welch, R.

    1993-01-01

    The third symposium on Remote Sensing of Snow and Ice, organized by the International Glaciological Society, took place in Boulder, Colorado, 17-22 May 1992. As part of this meeting a total of 21 papers was presented on snow and ice applications of Advanced Very High Resolution Radiometer (AVHRR) satellite data in polar regions. Also during this meeting a NASA sponsored Workshop was held to review the status of polar surface measurements from AVHRR. In the following we have summarized the ideas and recommendations from the workshop, and the conclusions of relevant papers given during the regular symposium sessions. The seven topics discussed include cloud masking, ice surface temperature, narrow-band albedo, ice concentration, lead statistics, sea-ice motion and ice-sheet studies with specifics on applications, algorithms and accuracy, following recommendations for future improvements. In general, we can affirm the strong potential of AVHRR for studying sea ice and snow covered surfaces, and we highly recommend this satellite data set for long-term monitoring of polar process studies. However, progress is needed to reduce the uncertainty of the retrieved parameters for all of the above mentioned topics to make this data set useful for direct climate applications such as heat balance studies and others. Further, the acquisition and processing of polar AVHRR data must become better coordinated between receiving stations, data centers and funding agencies to guarantee a long-term commitment to the collection and distribution of high quality data.

  17. Influence of ice thickness and surface properties on light transmission through Arctic sea ice.

    NASA Astrophysics Data System (ADS)

    Katlein, Christian; Arndt, Stefanie; Nicolaus, Marcel; Jakuba, Michael V.; Laney, Samuel; Elliott, Stephen; Whitcomb, Louis L.; McFarland, Christopher J.; Suman, Stefano; Gerdes, Rüdiger; Boetius, Antje; German, Christopher R.

    2015-04-01

    The observed changes in physical properties of sea ice such as decreased thickness and increased melt pond cover severely impact the energy balance of Arctic sea ice. Increased light transmission leads to increased deposition of solar energy and thus plays a crucial role for sea-ice-melt as well as for the amount and timing of under-ice primary production. Recent developments in underwater technology provide new opportunities to undertake challenging research at the largely inaccessible underside of sea ice. We measured spectral under-ice radiance and irradiance onboard the new Nereid Under-Ice (Nereid-UI) underwater robotic vehicle, during a cruise of the R/V Polarstern to 83°N 6°W in the Arctic Ocean in July 2014. Nereid-UI is a next generation hybrid remotely operated vehicle (H-ROV) designed for both remotely-piloted and autonomous surveys underneath fixed and moving sea ice. Here we present results from the first comprehensive scientific dive of Nereid-UI employing its interdisciplinary sensor suite. We combine under-ice optical measurements with three dimensional under-ice topography (multibeam sonar) and aerial images of the surface conditions. We investigate the influence of spatially varying ice-thickness and surface properties on the spatial variability of light transmittance on floe scale. Our results indicate that surface properties dominate the spatial distribution of the under-ice light field, while sea ice-thickness and snow-depth are most important for mean light levels.

  18. Observations of Recent Arctic Sea Ice Volume Loss and Its Impact on Ocean-Atmosphere Energy Exchange and Ice Production

    NASA Technical Reports Server (NTRS)

    Kurtz, N. T.; Markus, T.; Farrell, S. L.; Worthen, D. L.; Boisvert, L. N.

    2011-01-01

    Using recently developed techniques we estimate snow and sea ice thickness distributions for the Arctic basin through the combination of freeboard data from the Ice, Cloud, and land Elevation Satellite (ICESat) and a snow depth model. These data are used with meteorological data and a thermodynamic sea ice model to calculate ocean-atmosphere heat exchange and ice volume production during the 2003-2008 fall and winter seasons. The calculated heat fluxes and ice growth rates are in agreement with previous observations over multiyear ice. In this study, we calculate heat fluxes and ice growth rates for the full distribution of ice thicknesses covering the Arctic basin and determine the impact of ice thickness change on the calculated values. Thinning of the sea ice is observed which greatly increases the 2005-2007 fall period ocean-atmosphere heat fluxes compared to those observed in 2003. Although there was also a decline in sea ice thickness for the winter periods, the winter time heat flux was found to be less impacted by the observed changes in ice thickness. A large increase in the net Arctic ocean-atmosphere heat output is also observed in the fall periods due to changes in the areal coverage of sea ice. The anomalously low sea ice coverage in 2007 led to a net ocean-atmosphere heat output approximately 3 times greater than was observed in previous years and suggests that sea ice losses are now playing a role in increasing surface air temperatures in the Arctic.

  19. Arctic Sea Ice Predictability and the Sea Ice Prediction Network

    NASA Astrophysics Data System (ADS)

    Wiggins, H. V.; Stroeve, J. C.

    2014-12-01

    Drastic reductions in Arctic sea ice cover have increased the demand for Arctic sea ice predictions by a range of stakeholders, including local communities, resource managers, industry and the public. The science of sea-ice prediction has been challenged to keep up with these developments. Efforts such as the SEARCH Sea Ice Outlook (SIO; http://www.arcus.org/sipn/sea-ice-outlook) and the Sea Ice for Walrus Outlook have provided a forum for the international sea-ice prediction and observing community to explore and compare different approaches. The SIO, originally organized by the Study of Environmental Change (SEARCH), is now managed by the new Sea Ice Prediction Network (SIPN), which is building a collaborative network of scientists and stakeholders to improve arctic sea ice prediction. The SIO synthesizes predictions from a variety of methods, including heuristic and from a statistical and/or dynamical model. In a recent study, SIO data from 2008 to 2013 were analyzed. The analysis revealed that in some years the predictions were very successful, in other years they were not. Years that were anomalous compared to the long-term trend have proven more difficult to predict, regardless of which method was employed. This year, in response to feedback from users and contributors to the SIO, several enhancements have been made to the SIO reports. One is to encourage contributors to provide spatial probability maps of sea ice cover in September and the first day each location becomes ice-free; these are an example of subseasonal to seasonal, local-scale predictions. Another enhancement is a separate analysis of the modeling contributions. In the June 2014 SIO report, 10 of 28 outlooks were produced from models that explicitly simulate sea ice from dynamic-thermodynamic sea ice models. Half of the models included fully-coupled (atmosphere, ice, and ocean) models that additionally employ data assimilation. Both of these subsets (models and coupled models with data assimilation) have a far narrower spread in their prediction, indicating that the results of these more sophisticated methods are converging. Here we summarize and synthesize the 2014 contributions to the SIO, highlight the important questions and challenges that remain to be addressed, and present data on stakeholder uses of the SIO and related SIPN products.

  20. About uncertainties in sea ice thickness retrieval from satellite radar altimetry: results from the ESA-CCI Sea Ice ECV Project Round Robin Exercise

    NASA Astrophysics Data System (ADS)

    Kern, S.; Khvorostovsky, K.; Skourup, H.; Rinne, E.; Parsakhoo, Z. S.; Djepa, V.; Wadhams, P.; Sandven, S.

    2014-03-01

    One goal of the European Space Agency Climate Change Initiative sea ice Essential Climate Variable project is to provide a quality controlled 20 year long data set of Arctic Ocean winter-time sea ice thickness distribution. An important step to achieve this goal is to assess the accuracy of sea ice thickness retrieval based on satellite radar altimetry. For this purpose a data base is created comprising sea ice freeboard derived from satellite radar altimetry between 1993 and 2012 and collocated observations of snow and sea ice freeboard from Operation Ice Bridge (OIB) and CryoSat Validation Experiment (CryoVEx) air-borne campaigns, of sea ice draft from moored and submarine Upward Looking Sonar (ULS), and of snow depth from OIB campaigns, Advanced Microwave Scanning Radiometer aboard EOS (AMSR-E) and the Warren Climatology (Warren et al., 1999). An inter-comparison of the snow depth data sets stresses the limited usefulness of Warren climatology snow depth for freeboard-to-thickness conversion under current Arctic Ocean conditions reported in other studies. This is confirmed by a comparison of snow freeboard measured during OIB and CryoVEx and snow freeboard computed from radar altimetry. For first-year ice the agreement between OIB and AMSR-E snow depth within 0.02 m suggests AMSR-E snow depth as an appropriate alternative. Different freeboard-to-thickness and freeboard-to-draft conversion approaches are realized. The mean observed ULS sea ice draft agrees with the mean sea ice draft computed from radar altimetry within the uncertainty bounds of the data sets involved. However, none of the realized approaches is able to reproduce the seasonal cycle in sea ice draft observed by moored ULS satisfactorily. A sensitivity analysis of the freeboard-to-thickness conversion suggests: in order to obtain sea ice thickness as accurate as 0.5 m from radar altimetry, besides a freeboard estimate with centimetre accuracy, an ice-type dependent sea ice density is as mandatory as a snow depth with centimetre accuracy.

  1. Bio-optical characteristics of the snow, ice, and water column of a perennially ice-covered lake in

    E-print Network

    Vincent, Warwick F.

    Bio-optical characteristics of the snow, ice, and water column of a perennially ice-covered lake A is a meromictic, perennially ice-covered lake located at the northern limit of North America (latitude 83°N (PAR) was transmitted through its 2-m ice and 0.5-m snow cover. Removal of snow from 12 m2 increased

  2. Microwave signatures of snow and fresh water ice

    NASA Technical Reports Server (NTRS)

    Schmugge, T.; Wilheit, T. T.; Gloersen, P.; Meier, M. F.; Frank, D.; Dirmhirn, I.

    1973-01-01

    During March of 1971, the NASA Convair 990 Airborne Observatory carrying microwave radiometers in the wavelength range 0.8 to 21 cm was flown over dry snow with different substrata: Lake ice at Bear Lake in Utah; wet soil in the Yampa River Valley near Steamboat Springs, Colorado; and glacier ice, firm and wet snow on the South Cascade Glacier in Washington. The data presented indicate that the transparency of the snow cover is a function of wavelength. False-color images of microwave brightness temperatures obtained from a scanning radiometer operating at a wavelength of 1.55 cm demonstrate the capability of scanning radiometers for mapping snowfields.

  3. C-Band Backscatter Measurements of Winter Sea-Ice in the Weddell Sea, Antarctica

    NASA Technical Reports Server (NTRS)

    Drinkwater, M. R.; Hosseinmostafa, R.; Gogineni, P.

    1995-01-01

    During the 1992 Winter Weddell Gyre Study, a C-band scatterometer was used from the German ice-breaker R/V Polarstern to obtain detailed shipborne measurement scans of Antarctic sea-ice. The frequency-modulated continuous-wave (FM-CW) radar operated at 4-3 GHz and acquired like- (VV) and cross polarization (HV) data at a variety of incidence angles (10-75 deg). Calibrated backscatter data were recorded for several ice types as the icebreaker crossed the Weddell Sea and detailed measurements were made of corresponding snow and sea-ice characteristics at each measurement site, together with meteorological information, radiation budget and oceanographic data. The primary scattering contributions under cold winter conditions arise from the air/snow and snow/ice interfaces. Observations indicate so e similarities with Arctic sea-ice scattering signatures, although the main difference is generally lower mean backscattering coefficients in the Weddell Sea. This is due to the younger mean ice age and thickness, and correspondingly higher mean salinities. In particular, smooth white ice found in 1992 in divergent areas within the Weddell Gyre ice pack was generally extremely smooth and undeformed. Comparisons of field scatterometer data with calibrated 20-26 deg incidence ERS-1 radar image data show close correspondence, and indicate that rough Antarctic first-year and older second-year ice forms do not produce as distinctively different scattering signatures as observed in the Arctic. Thick deformed first-year and second-year ice on the other hand are clearly discriminated from younger undeformed ice. thereby allowing successful separation of thick and thin ice. Time-series data also indicate that C-band is sensitive to changes in snow and ice conditions resulting from atmospheric and oceanographic forcing and the local heat flux environment. Variations of several dB in 45 deg incidence backscatter occur in response to a combination of thermally-regulated parameters including sea-ice brine volume, snow and ice complex dielectric properties, and snow physical properties.

  4. Helicopter borne radar derived snow thickness estimates over fast ice in East Antarctica

    NASA Astrophysics Data System (ADS)

    Galin, N.; Markus, T.; Worby, A. P.; Leuschen, C.; Gogineni, P. S.

    2009-12-01

    The polar regions play a key role in the Earth's climate system, and sea ice has a major influence on ocean-atmosphere interaction and ocean circulation. Antarctic sea ice and its snow cover are integral components of the global climate system, yet their thickness and variability are poorly understood and subsequently their representation in global climate models is poor. Remote sensing is the key to monitoring the dynamic nature and changes of sea ice and its snow cover. Snow depth on sea ice is operationally derived from the EOS Aqua Advanced Microwave Scanning Radiometer (AMSR-E) measurements but thorough validation is still an issue. To address this, research is currently directed to airborne snow depth investigation techniques capable of covering large areas to validate satellite data. In October - November, 2008 a helicopter equipped with a laser altimeter, a 2 - 8 GHz FMCW radar and a digital camera was flown over the fast ice near to the Australian base, Davis, 68.35' S, 77.58' E. An area 80 x 200 m was over flown repeatedly by the helicopter at varying altitudes and velocities for cross validation and precision assessment purposes. Thorough in-situ measurements were gathered over the area for ground truth purposes. From this data it is seen that the range of snow thickness is up to 300mm, placing stringent requirements on the accuracy of the radar that theoretically has a vertical resolution of 25mm. The process of extracting snow thickness estimates from the helicopter borne radar measurements has so far been hampered by the noise in the radar not only by the instability of the helicopter, but also by the aggravation of the noise with increasing altitude. Fortunately, it was found that the noise is of a predicable nature and it has been possible to clean up the radar signal. Subsequently, implementing this denoising algorithm across the full gathered dataset, in this paper the first helicopter borne radar derived snow thickness estimates over fast ice in Antarctica are presented and compared with the in-situ data. Five mile long transects over which ship based observation data was gathered will also be analysed for snow thickness distribution.

  5. Measurements of sea ice proxies from Antarctic coastal shallow cores

    NASA Astrophysics Data System (ADS)

    Maffezzoli, Niccolò; Vallelonga, Paul; Spolaor, Andrea; Barbante, Carlo; Frezzotti, Massimo

    2015-04-01

    Despite its close relationship with climate, the climatic impact of sea ice remains only partially understood: an indication of this is the Arctic sea ice which is declining at a faster rate than models predict. Thus, the need for reliable sea ice proxies is of crucial importance. Among the sea ice proxies that can be extracted from ice cores, interest has recently been shown in the halogens Iodine (I) and Bromine (Br) (Spolaor, A., et al., 2013a, 2013b). The production of sea ice is a source of Sodium and Bromine aerosols through frost flower crystal formation and sublimation of salty blowing snow, while Iodine is emitted by the algae living underneath sea ice. We present here the results of Na, Br and I measurements in Antarctic shallow cores, drilled during a traverse made in late 2013 - early 2014 from Talos Dome (72° 00'S, 159°12'E) to GV7 (70° 41'S, 158° 51'E) seeking for sea ice signature. The samples were kept frozen until the analyses, that were carried out by Sector Field Mass Spectroscopy Inductive Coupled Plasma (SFMS-ICP): special precautions and experimental steps were adopted for the detection of such elements. The coastal location of the cores allows a clear signal from the nearby sea ice masses. The multiple cores are located about 50 km from each other and can help us to infer the provenance of the sea ice that contributed to the proxy signature. Moreover, by simultaneously determining other chemical elements and compounds in the snow, it is possible to determine the relative timing of their deposition, thus helping us to understand their processes of emission and deposition.

  6. Remote sensing of ice and snow - Review and status

    NASA Technical Reports Server (NTRS)

    Carsey, Frank

    1992-01-01

    The interpretation of satellite data is reviewed to address the possibility of extracting geophysically useful data regarding ice and snow. The scientific and practical utility of such data is examined in terms of the required and available scales, resolutions, and data types. Satellite instrumentation for ice and snow studies includes the AVHRR, the Special Sensor Microwave Imager, and the altimeters on Geosat and the European Remote Sensing Satellite. The satellites are presently used for conducting investigations of the microwave radiometry of snow, shortwave snowcover inventories, and sensor and model validations. It is noted that these studies encompass a range of ice properties and employ approaches and scientists from a number of fields. Areas that remain to be addressed in the field include snow structure and substrate effects, fall cooling, floe flooding, and brine expulsion.

  7. Life Cycle of Sea-Ice Frazil, or grease ice

    E-print Network

    Washington at Seattle, University of

    Life Cycle of Sea-Ice Sea-water ~ 35 psu Frazil, or grease ice - small crystals Thickens Nilas Thickens Ice Floes Calm Conditions Rough Conditions Pancake Ice Thickens Thickening: - thermodynamic = congelation ice - mechanical = finger rafting = ridging FIRST-YEAR ICE ~ 4-10 psu flat and ridged 1-2 m thick

  8. Cladoceran zooplankton abundance under clear and snow-covered ice

    USGS Publications Warehouse

    DeBates, T.J.; Chipps, S.R.; Ward, M.C.; Werlin, K.B.; Lorenzen, P.B.

    2003-01-01

    We described the distribution of cladoceran zooplankton under the ice in a natural, glacial lake. Local light availability apparently altered the spatial distribution of cladocerans. Light levels measured under snow-covered areas (0.178 lux) were an order of magnitude less than those measured at the same depth under clear ice (1.750 lux). Cladoceran density under snow-covered areas was significantly higher (Bosmina spp.=3.34/L; Daphnia spp.=0.61/L) than cladoceran abundance under clear ice (Bosmina spp.=0.91/L; Daphnia spp.=0.19/L).

  9. Physical characteristics of summer sea ice across the Arctic Ocean

    USGS Publications Warehouse

    Tucker, W. B., III; Gow, A.J.; Meese, D.A.; Bosworth, H.W.; Reimnitz, E.

    1999-01-01

    Sea ice characteristics were investigated during July and August on the 1994 transect across the Arctic Ocean. Properties examined from ice cores included salinity, temperature, and ice structure. Salinities measured near zero at the surface, increasing to 3-4??? at the ice-water interface. Ice crystal texture was dominated by columnar ice, comprising 90% of the ice sampled. Surface albedos of various ice types, measured with radiometers, showed integrated shortwave albedos of 0.1 to 0.3 for melt ponds, 0.5 for bare, discolored ice, and 0.6 to 0.8 for a deteriorated surface or snow-covered ice. Aerial photography was utilized to document the distribution of open melt ponds, which decreased from 12% coverage of the ice surface in late July at 76??N to almost none in mid-August at 88??N. Most melt ponds were shallow, and depth bore no relationship to size. Sediment was pervasive from the southern Chukchi Sea to the north pole, occurring in bands or patches. It was absent in the Eurasian Arctic, where it had been observed on earlier expeditions. Calculations of reverse trajectories of the sediment-bearing floes suggest that the southernmost sediment was entrained during ice formation in the Beaufort Sea while more northerly samples probably originated in the East Siberian Sea, some as far west as the New Siberian Islands.

  10. Kindergarten Explorations with Snow, Ice, and Water

    ERIC Educational Resources Information Center

    Carroll, Martha A.

    1978-01-01

    Using winter snow, kindergarten students can explore the properties of water. Students demonstrate melting, freezing, expansion, and evaporation through a number of activities involving a paper cup and a scoop of snow. Procedures and student reactions are described in detail by the teacher-author. (MA)

  11. Towards a satellite-based sea ice climate data record

    NASA Astrophysics Data System (ADS)

    Meier, W. N.; Fetterer, F.; Stroeve, J.; Cavalieri, D.; Parkinson, C.; Comiso, J.; Weaver, R.

    2005-12-01

    Sea ice plays an important role in the Earth's climate through its influence on the surface albedo, heat and moisture transfer between the ocean and the atmosphere, and the thermohaline circulation. Satellite data reveal that since 1979, summer Arctic sea ice has, overall, been declining at a rate of almost 8%/decade, with recent summers (beginning in 2002) being particularly low. The receding sea ice is having an effect on wildlife and indigenous peoples in the Arctic, and concern exists that these effects may become increasingly severe. Thus, a long-term, ongoing climate data record of sea ice is crucial for tracking the changes in sea ice and for assessing the significance of long-term trends. Since the advent of passive microwave satellite instruments in the early 1970s, sea ice has been one of the most consistently monitored climate parameters. There is now a 27+ year record of sea ice extent and concentration from multi-channel passive microwave radiometers that has undergone inter-sensor calibration and other quality controls to ensure consistency throughout the record. Several algorithms have been developed over the years to retrieve sea ice extent and concentration and two of the most commonly used algorithms, the NASA Team and Bootstrap, have been applied to the entire SMMR-SSM/I record to obtain a consistent time series. These algorithms were developed at NASA Goddard Space Flight Center and are archived at the National Snow and Ice Data Center. However, the complex surface properties of sea ice affect the microwave signature, and algorithms can yield ambiguous results; no single algorithm has been found to work uniformly well under all sea ice conditions. Thus there are ongoing efforts to further refine the algorithms and the time series. One approach is to develop data fusion methods to optimally combine sea ice fields from two or more algorithms. Another approach is to take advantage of the improved capabilities of JAXA's AMSR-E sensor on NASA's Aqua satellite to provide improved parameters and additional insights into deficiencies in the SMMR-SSM/I products. Finally, other fertile sources of sea ice information are operational sea ice charts, such as those produced at the U.S. National Ice Center (NIC). There is a 23-year (1972-1994) record of sea ice available from the NIC ice charts and an update is in progress. These charts have already been used to evaluate passive microwave retrievals and to extend the SMMR-SSM/I time series back to late 1972, when a proof-of-concept single-channel ESMR radiometer began operation.

  12. Ice2sea initial progress

    NASA Astrophysics Data System (ADS)

    Ford, Elaina; Vaughan, David

    2010-05-01

    Ice2sea is an EU Framework 7 funded project with 24 partners across Europe with the goal of constraining predictions of contributions of continental ice to sea-level rise over the next 200 years. We will do this through an integrated programme that includes targeted studies of key processes in mountain glacier systems and ice caps (e.g. Svalbard, Patagonia), and in ice sheets in both polar regions (Greenland and Antarctica); improved satellite determinations of changes in continental ice mass; development and implementation of ice-sheet/glacier models to generate detailed projections of the contribution of continental ice to sea-level rise over the next 200 years. We will deliver these results in forms accessible to scientists, policy-makers and the general public, which will include clear presentations of the sources of uncertainty. We are now a year into the project and in addition to some initial model output, recent field campaigns have provided data to be analysed. We summarise progress made to date, the targets for the coming year, and explain how you can stand informed and perhaps get involved in ice2sea.

  13. Drifting snow climate of the Antarctic and Greenland ice sheets

    NASA Astrophysics Data System (ADS)

    Lenaerts, J. T. M.

    2013-02-01

    This study presents the drifting snow climate of the Earth's ice sheets, Antarctica and Greenland. For that purpose we use a regional atmospheric climate model, RACMO2. We included a routine that is able to calculate the drifting snow fluxes and accounts for the interaction between drifting snow on the one hand and the atmosphere and snow surface on the other. RACMO2 is run at 27 km resolution for Antarctica, and 11 km resolution for Greenland, and forced at its lateral boundaries by ECMWF reanalyses (32 years for Antarctica and 52 years for Greenland). Because direct evaluation for drifting snow is challenging due to sparseness of observational data, we focussed the model evaluation on the ability of RACMO2 to represent near-surface wind climate, temperature, surface mass balance, the extent of ablation areas and remote-sensed drifting snow frequency. We show that RACMO2 is very well able to represent the present-day near-surface climate of Antarctica and Greenland. Drifting snow occurs 20-80% of the time on Antarctica, depending on the local wind climate. Highest frequencies are found in the coastal areas, where drifting snow sublimation (SUds) removes up to 150 mm water equivalent of snow, whereas the high-elevation areas experience little or no SUds. Drifting snow erosion (ER­ds) can be negative (deposition) or positive (erosion), and varies generally between -50 and 50 mm in regions where the wind field convergences and diverges, respectively. Integrated over the ice sheet, SUds removes around 165 Gt of snow, which is equivalent to ~6% of the precipitated snow. The impact of ER­ds on the Antarctic ice sheet SMB is negligible . We found several feedbacks between SUds and the atmosphere. SUds moistens the near-surface atmosphere, limiting its own potential, but also enhancing precipitation in some coastal areas. By removing mass from the snow surface, drifting snow processes increase the top snow layer density, increasing the threshold wind speed for further drifting snow. Since the impacts of drifting snow are included, we are able to quantify all contributors to the Antarctic SMB. The SMB equals 2479 +/- 147 Gt/yr, and is largely determined by snowfall. It varies from <50 mm/yr on the East Antarctic Plateau to more than 2000 mm/yr in coastal West Antarctica and the Antarctic Peninsula. Mass is primarly removed by SUds, because all meltwater produced refreezes in the snowpack, and surface sublimation equals only ~30% of SUds. The influence of model resolution on the resulting impact of drifting snow on the East Antarctic SMB is small, although locally ERds is much more significant due to the better representation of small-scale topography and related wind gradients. The impact of drifting snow on the Greenland ice sheet SMB is generally less significant than on Antarctica, due to lower wind speeds, more melt that increases the snow density, and warmer temperatures. SUds equals 24 Gt/yr, equivalent to ~3% of the precipitation, and is only a winter phenomenon on Greenland. Ablation on Greenland is primarly governed by meltwater runoff in summer.

  14. Surface-based passive microwave studies of multiyear sea ice

    NASA Technical Reports Server (NTRS)

    Grenfell, T. C.

    1992-01-01

    Results are presented on surface-based multifrequency passive microwave observations of multiyear (MY) sea ice in the eastern Arctic Basin, the Beaufort Sea, the Canadian archipelago, and the northern Greenland Sea. The analyses of these data show that the magnitude of the spectral gradient of emissivity is directly related to the existence and the thickness of a decomposed surface ice layer with very high porosity. Spectra for melt ponds with a frozen surface layer closely resembled those of lake ice and showed a positive spectral gradient. The variance among emissivity spectra for MY ice was caused primarily by the distributions of melt ponds and by the presence of significant amounts of scattering inhomogeneities in the snow and the upper 20-30-cm layer of the ice.

  15. Polar bear and walrus response to the rapid decline in Arctic sea ice

    USGS Publications Warehouse

    Oakley, K.; Whalen, M.; Douglas, D.; Udevitz, M.; Atwood, T.; Jay, C.

    2012-01-01

    The Arctic is warming faster than other regions of the world due to positive climate feedbacks associated with loss of snow and ice. One highly visible consequence has been a rapid decline in Arctic sea ice over the past 3 decades - a decline projected to continue and result in ice-free summers likely as soon as 2030. The polar bear (Ursus maritimus) and the Pacific walrus (Odobenus rosmarus divergens) are dependent on sea ice over the continental shelves of the Arctic Ocean's marginal seas. The continental shelves are shallow regions with high biological productivity, supporting abundant marine life within the water column and on the sea floor. Polar bears use sea ice as a platform for hunting ice seals; walruses use sea ice as a resting platform between dives to forage for clams and other bottom-dwelling invertebrates. How have sea ice changes affected polar bears and walruses? How will anticipated changes affect them in the future?

  16. Arctic sea ice decline: Projected changes in timing and extent of sea ice in the Bering and Chukchi Seas

    USGS Publications Warehouse

    Douglas, D.C.

    2010-01-01

    The Arctic region is warming faster than most regions of the world due in part to increasing greenhouse gases and positive feedbacks associated with the loss of snow and ice cover. One consequence has been a rapid decline in Arctic sea ice over the past 3 decades?a decline that is projected to continue by state-of-the-art models. Many stakeholders are therefore interested in how global warming may change the timing and extent of sea ice Arctic-wide, and for specific regions. To inform the public and decision makers of anticipated environmental changes, scientists are striving to better understand how sea ice influences ecosystem structure, local weather, and global climate. Here, projected changes in the Bering and Chukchi Seas are examined because sea ice influences the presence of, or accessibility to, a variety of local resources of commercial and cultural value. In this study, 21st century sea ice conditions in the Bering and Chukchi Seas are based on projections by 18 general circulation models (GCMs) prepared for the fourth reporting period by the Intergovernmental Panel on Climate Change (IPCC) in 2007. Sea ice projections are analyzed for each of two IPCC greenhouse gas forcing scenarios: the A1B `business as usual? scenario and the A2 scenario that is somewhat more aggressive in its CO2 emissions during the second half of the century. A large spread of uncertainty among projections by all 18 models was constrained by creating model subsets that excluded GCMs that poorly simulated the 1979-2008 satellite record of ice extent and seasonality. At the end of the 21st century (2090-2099), median sea ice projections among all combinations of model ensemble and forcing scenario were qualitatively similar. June is projected to experience the least amount of sea ice loss among all months. For the Chukchi Sea, projections show extensive ice melt during July and ice-free conditions during August, September, and October by the end of the century, with high agreement among models. High agreement also accompanies projections that the Chukchi Sea will be completely ice covered during February, March, and April at the end of the century. Large uncertainties, however, are associated with the timing and amount of partial ice cover during the intervening periods of melt and freeze. For the Bering Sea, median March ice extent is projected to be about 25 percent less than the 1979-1988 average by mid-century and 60 percent less by the end of the century. The ice-free season in the Bering Sea is projected to increase from its contemporary average of 5.5 months to a median of about 8.5 months by the end of the century. A 3-month longer ice- free season in the Bering Sea is attained by a 1-month advance in melt and a 2-month delay in freeze, meaning the ice edge typically will pass through the Bering Strait in May and January at the end of the century rather than June and November as presently observed.

  17. Multiple Scattering of Laser Pulses in Snow Over Ice: Modeling the Potential Bias in ICESat Altimetry

    NASA Technical Reports Server (NTRS)

    Davis, A. B.; Varnai, T.; Marshak, A.

    2010-01-01

    The primary goal of NASA's current ICESat and future ICESat2 missions is to map the altitude of the Earth's land ice with high accuracy using laser altimetry technology, and to measure sea ice freeboard. Ice however is a highly transparent optical medium with variable scattering and absorption properties. Moreover, it is often covered by a layer of snow with varying depth and optical properties largely dependent on its age. We describe a modeling framework for estimating the potential altimetry bias caused by multiple scattering in the layered medium. We use both a Monte Carlo technique and an analytical diffusion model valid for optically thick media. Our preliminary numerical results are consistent with estimates of the multiple scattering delay from laboratory measurements using snow harvested in Greenland, namely, a few cm. Planned refinements of the models are described.

  18. 30 CFR 56.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Snow and ice on walkways and travelways. ...NONMETAL MINES Travelways § 56.11016 Snow and ice on walkways and travelways. ...shall be sanded, salted, or cleared of snow and ice as soon as...

  19. 30 CFR 57.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Snow and ice on walkways and travelways. ...Travelways-Surface and Underground § 57.11016 Snow and ice on walkways and travelways. ...shall be sanded, salted, or cleared of snow and ice as soon as...

  20. 30 CFR 56.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Snow and ice on walkways and travelways. ...NONMETAL MINES Travelways § 56.11016 Snow and ice on walkways and travelways. ...shall be sanded, salted, or cleared of snow and ice as soon as...

  1. 30 CFR 56.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Snow and ice on walkways and travelways. ...NONMETAL MINES Travelways § 56.11016 Snow and ice on walkways and travelways. ...shall be sanded, salted, or cleared of snow and ice as soon as...

  2. 30 CFR 56.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Snow and ice on walkways and travelways. ...NONMETAL MINES Travelways § 56.11016 Snow and ice on walkways and travelways. ...shall be sanded, salted, or cleared of snow and ice as soon as...

  3. 30 CFR 57.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Snow and ice on walkways and travelways. ...Travelways-Surface and Underground § 57.11016 Snow and ice on walkways and travelways. ...shall be sanded, salted, or cleared of snow and ice as soon as...

  4. 30 CFR 57.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Snow and ice on walkways and travelways. ...Travelways-Surface and Underground § 57.11016 Snow and ice on walkways and travelways. ...shall be sanded, salted, or cleared of snow and ice as soon as...

  5. 30 CFR 56.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Snow and ice on walkways and travelways. ...NONMETAL MINES Travelways § 56.11016 Snow and ice on walkways and travelways. ...shall be sanded, salted, or cleared of snow and ice as soon as...

  6. 30 CFR 57.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Snow and ice on walkways and travelways. ...Travelways-Surface and Underground § 57.11016 Snow and ice on walkways and travelways. ...shall be sanded, salted, or cleared of snow and ice as soon as...

  7. 30 CFR 57.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Snow and ice on walkways and travelways. ...Travelways-Surface and Underground § 57.11016 Snow and ice on walkways and travelways. ...shall be sanded, salted, or cleared of snow and ice as soon as...

  8. Modeling of snow and ice melt at ETH Camp (West Greenland): A study of surface albedo

    E-print Network

    Gallée, Hubert

    Modeling of snow and ice melt at ETH Camp (West Greenland): A study of surface albedo Filip Lefebre is to present the validation over Greenland of a thermodynamic snow-ice model that was complemented melt. The development of an integrated (snow, ice, and water) albedo model takes into account

  9. 30 CFR 56.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Snow and ice on walkways and travelways. 56... Travelways § 56.11016 Snow and ice on walkways and travelways. Regularly used walkways and travelways shall be sanded, salted, or cleared of snow and ice as soon as practicable....

  10. 30 CFR 56.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Snow and ice on walkways and travelways. 56... Travelways § 56.11016 Snow and ice on walkways and travelways. Regularly used walkways and travelways shall be sanded, salted, or cleared of snow and ice as soon as practicable....

  11. 30 CFR 56.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Snow and ice on walkways and travelways. 56... Travelways § 56.11016 Snow and ice on walkways and travelways. Regularly used walkways and travelways shall be sanded, salted, or cleared of snow and ice as soon as practicable....

  12. 30 CFR 56.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Snow and ice on walkways and travelways. 56... Travelways § 56.11016 Snow and ice on walkways and travelways. Regularly used walkways and travelways shall be sanded, salted, or cleared of snow and ice as soon as practicable....

  13. 30 CFR 56.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Snow and ice on walkways and travelways. 56... Travelways § 56.11016 Snow and ice on walkways and travelways. Regularly used walkways and travelways shall be sanded, salted, or cleared of snow and ice as soon as practicable....

  14. Snow and Ice Crust Changes over Northern Eurasia since 1966

    NASA Astrophysics Data System (ADS)

    Bulygina, O.; Groisman, P. Y.; Razuvaev, V.; Radionov, V.

    2009-12-01

    When temperature of snow cover reaches zero Celsius first time since its establishment, snowmelt starts. In many parts of the world this process can be lengthy. The initial amount of heat that “arrives” to the snowpack might be insufficient for complete snowmelt, during the colder nights re-freeze of the melted snow may occur (thus creating the ice crust layers), and a new cold front (or the departure of the warm front that initiated melt) can decrease temperatures below the freezing point again and stop the snowmelt completely. It well can be that first such snowmelt occurs in winter (thaw day) and for several months thereafter snowpack stays on the ground. However, even the first such melt initiates a process of snow metamorphosis on its surface changing snow albedo and generating snow crust as well as on its bottom generating ice crust. Once emerged, the crusts will not disappear until the complete snowmelt. Furthermore, these crusts have numerous pathways of impact on the wild birds and animals in the Arctic environment as well as on domesticated reindeers. In extreme cases, the crusts may kill some wild species and prevent reindeers’ migration and feeding. Ongoing warming in high latitudes created situations when in the western half of Eurasian continent days with thaw became more frequent. Keeping in mind potential detrimental impacts of winter thaws and associated with them snow/ice crust development, it is worthwhile to study directly what are the major features of snow and ice crust over Eurasia and what is their dynamics. For the purpose of this study, we employed the national snow survey data set archived at the Russian Institute for Hydrometeorological Information. The dataset has routine snow surveys run throughout the cold season each decade (during the intense snowmelt, each 5 days) at all meteorological stations of the former USSR, thereafter, in Russia since 1966. Prior to 1966 snow surveys are also available but the methodology of observations has substantially changed at that year. Therefore, this analysis includes only data of 585 Russian stations from 1966 to 2008 that have all years of data with a minimal number of missing observations. Surveys run separately along all types of environment typical for the site for 1 to 2 km, describing the current snow cover properties including characteristics of snow and ice crust. Joint analysis of these characteristics of crust together with a suite of synoptic information at the stations allows us to empirically assess the process of snow and ice crust formation and development throughout the cold season and outline major factors responsible for their dynamics. Finally, regional averaging and time series analysis of both, these factors and the crust characteristics themselves, answer the question about the regional climatic changes of snow and ice crusts over Northern Eurasia, including those crust characteristics that are of practical importance for reindeer husbandry. These results for the Russian Federation will be presented at the Meeting.

  15. 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.

  16. Variability of Arctic Sea Ice as Viewed from Space

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.

    1998-01-01

    Over the past 20 years, satellite passive-microwave radiometry has provided a marvelous means for obtaining information about the variability of the Arctic sea ice cover and particularly about sea ice concentrations (% areal coverages) and from them ice extents and the lengths of the sea ice season. This ability derives from the sharp contrast between the microwave emissions of sea ice versus liquid water and allows routine monitoring of the vast Arctic sea ice cover, which typically varies in extent from a minimum of about 8,000,000 sq km in September to a maximum of about 15,000,000 sq km in March, the latter value being over 1.5 times the area of either the United States or Canada. The vast Arctic ice cover has many impacts, including hindering heat, mass, and y momentum exchanges between the oceans and the atmosphere, reducing the amount of solar radiation absorbed at the Earth's surface, affecting freshwater transports and ocean circulation, and serving as a vital surface for many species of polar animals. These direct impacts also lead to indirect impacts, including effects on local and perhaps global atmospheric temperatures, effects that are being examined in general circulation modeling studies, where preliminary results indicate that changes on the order of a few percent sea ice concentration can lead to temperature changes of 1 K or greater even in local areas outside of the sea ice region. Satellite passive-microwave data for November 1978 through December 1996 reveal marked regional and interannual variabilities in both the ice extents and the lengths of the sea ice season, as well as some statistically significant trends. For the north polar ice cover as a whole, maximum ice extents varied over a range of 14,700,000 - 15,900,000 km(2), while individual regions showed much greater percentage variations, e.g., with the Greenland Sea experiencing a range of 740,000 - 1,1110,000 km(2) in its yearly maximum ice coverage. Although variations from year to year and region to region are large, overall the Arctic ice extents did show a statistically significant, 2.8%/ decade negative trend over the 18.2-year period. Ice season lengths, which vary from only a few weeks near the ice margins to the full year in the large region of perennial ice coverage, also experienced interannual variability, and mapping their trends allows detailed geographic information on exactly where the ice season lengthened and where it shortened. Over the 18 years, ice season lengthening occurred predominantly in the western hemisphere and was strongest in the western Labrador Sea, while ice season shortening occurred predominantly in the eastern hemisphere and was strongest in the eastern Barents Sea. Much information about other important Arctic sea ice variables has also been obtained from satellite data, including information about melt ponding, temperature, snow cover, and ice velocities. For instance, maps of ice velocities have now been made from satellite scatterometry data, including information about melt ponding, temperature, snow cover, and ice velocities.

  17. Observed and Modeled Trends in Southern Ocean Sea Ice

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.

    2003-01-01

    Conceptual models and global climate model (GCM) simulations have both indicated the likelihood of an enhanced sensitivity to climate change in the polar regions, derived from the positive feedbacks brought about by the polar abundance of snow and ice surfaces. Some models further indicate that the changes in the polar regions can have a significant impact globally. For instance, 37% of the temperature sensitivity to a doubling of atmospheric CO2 in simulations with the GCM of the Goddard Institute for Space Studies (GISS) is attributable exclusively to inclusion of sea ice variations in the model calculations. Both sea ice thickness and sea ice extent decrease markedly in the doubled CO, case, thereby allowing the ice feedbacks to occur. Stand-alone sea ice models have shown Southern Ocean hemispherically averaged winter ice-edge retreats of 1.4 deg latitude for each 1 K increase in atmospheric temperatures. Observations, however, show a much more varied Southern Ocean ice cover, both spatially and temporally, than many of the modeled expectations. In fact, the satellite passive-microwave record of Southern Ocean sea ice since late 1978 has revealed overall increases rather than decreases in ice extents, with ice extent trends on the order of 11,000 sq km/year. When broken down spatially, the positive trends are strongest in the Ross Sea, while the trends are negative in the Bellingshausen/Amundsen Seas. Greater spatial detail can be obtained by examining trends in the length of the sea ice season, and those trends show a coherent picture of shortening sea ice seasons throughout almost the entire Bellingshausen and Amundsen Seas to the west of the Antarctic Peninsula and in the far western Weddell Sea immediately to the east of the Peninsula, with lengthening sea ice seasons around much of the rest of the continent. This pattern corresponds well with the spatial pattern of temperature trends, as the Peninsula region is the one region in the Antarctic with a strong record of temperature increases. Still, although the patterns of the temperature and ice changes match fairly well, there is a substantial ways to go before these patterns are understood (and can be modeled) in the full context of global change.

  18. Ice nucleation: elemental identification of particles in snow crystals.

    PubMed

    Parungo, F P; Pueschel, R F

    1973-06-01

    A scanning field-emission electron microscope combined with an x-ray analyzer is used to locate the ice nucleus within a three-dimensional image of a snow crystal and determine the chemical composition of the nucleus. This makes it possible to better understand the effect of nuclei in cloud seeding. PMID:17806581

  19. ICESat Observations of Arctic Sea Ice: A First Look

    NASA Technical Reports Server (NTRS)

    Kwok, Ron; Zwally, H. Jay; Yi, Donghui

    2004-01-01

    Analysis of near-coincident ICESat and RADARSAT imagery shows that the retrieved elevations from the laser altimeter are sensitive to new openings (containing thin ice or open water) in the sea ice cover as well as to surface relief of old and first-year ice. The precision of the elevation estimates, measured over relatively flat sea ice, is approx. 2 cm. Using the thickness of thin-ice in recent openings to estimate sea level references, we obtain the sea-ice freeboard along the altimeter tracks. This step is necessitated by the large uncertainties in the sea surface topography compared to that required for accurate determination of freeboard. Unknown snow depth introduces the largest uncertainty in the conversion of freeboard to ice thickness. Surface roughness is also derived, for the first time, from the variability of successive elevation estimates along the altimeter track. Overall, these ICESat measurements provide an unprecedented view of the Arctic Ocean ice cover at length scales at and above the spatial dimension of the altimeter footprint of approx. 70 m.

  20. ICESat Observations of Arctic Sea Ice: A First Look

    NASA Technical Reports Server (NTRS)

    Kwok, Ron; Zwally, H. Jay; Yi, Dong-Hui

    2004-01-01

    Analysis of near-coincident ICESat and RADARSAT imagery shows that the retrieved elevations from the laser altimeter are sensitive to new openings (containing thin ice or open water) in the sea ice cover as well as to surface relief of old and first-year ice. The precision of the elevation estimates, measured over relatively flat sea ice, is approx. 2 cm Using the thickness of thin-ice in recent openings to estimate sea level references, we obtain the sea-ice free-board along the altimeter tracks. This step is necessitated by the large uncertainties in the time-varying sea surface topography compared to that required for accurate determination of free-board. Unknown snow depth introduces the largest uncertainty in the conversion of free-board to ice thickness. Surface roughness is also derived, for the first time, from the variability of successive elevation estimates along the altimeter track Overall, these ICESat measurements provide an unprecedented view of the Arctic Ocean ice cover at length scales at and above the spatial dimension of the altimeter footprint.

  1. The ability of CryoSat-2 to measure Antarctic sea ice freeboard

    NASA Astrophysics Data System (ADS)

    Price, Daniel; Rack, Wolfgang; Beckers, Justin; Ricker, Robert; Kurtz, Nathan; Haas, Christian; Helm, Veit; Hendricks, Stefan; Leonard, Greg; Langhorne, Pat

    2015-04-01

    Antarctic sea ice cover has been routinely monitored since 1979 but sea ice thickness remains one of the least understood physical components of the global cryosphere. Quantification of thickness is of crucial importance, since when combined with areal data it allows the computation of sea ice volume providing insight into the heat budget of the Antarctic sea ice system and quantification of freshwater and saltwater fluxes in the Southern Ocean. The use of satellite altimetry for sea ice thickness estimation relies on the measurement of freeboard. Thickness can then be estimated based on the assumptions of hydrostatic equilibrium given densities of snow, ice, water, and snow thickness are known. Using in situ data for 2011 and 2013 we evaluate the ability of CryoSat-2 (CS-2) to retrieve sea ice freeboard over fast-ice in McMurdo Sound. European Space Agency Level 2 data (ESAL2) is compared with results of a Waveform Fitting procedure (WfF) and a Threshold-First-Maximum-Retracker-Algorithm employed at 40% (TFMRA40). A supervised freeboard retrieval procedure is used to reduce errors associated with sea surface height identification and radar velocity in snow. We find ESAL2 freeboards located between the ice and snow freeboard rather than the frequently assumed snow-ice interface. WfF is within 0.04 m of the ice freeboard but is influenced by variable snow conditions causing increased radar backscatter from the air/snow interface; in such conditions a positive bias of 0.14 m away from the ice freeboard is observed. TFMRA40 freeboards are within 0.03 m of the snow freeboard. The difference in freeboard estimates is primarily driven by different retracker assumptions, although waveform alteration by variations in snow properties and surface roughness is evident. Techniques were amended where necessary and automatic freeboard retrieval procedures for ESAL2, WfF and TFMRA40 were developed. CS-2 detects annual fast-ice freeboard trends in McMurdo Sound using all three automatic procedures that are in line with known sea ice growth rates in the region. We present a systematic validation of CS-2 in the coastal Antarctic and provide insight into the assumptions currently used to process CS-2 data.

  2. Snow crystal imaging using scanning electron microscopy: III. Glacier ice, snow and biota

    USGS Publications Warehouse

    Rango, A.; Wergin, W.P.; Erbe, E.F.; Josberger, E.G.

    2000-01-01

    Low-temperature scanning electron microscopy (SEM) was used to observe metamorphosed snow, glacial firn, and glacial ice obtained from South Cascade Glacier in Washington State, USA. Biotic samples consisting of algae (Chlamydomonas nivalis) and ice worms (a species of oligochaetes) were also collected and imaged. In the field, the snow and biological samples were mounted on copper plates, cooled in liquid nitrogen, and stored in dry shipping containers which maintain a temperature of -196??C. The firn and glacier ice samples were obtained by extracting horizontal ice cores, 8 mm in diameter, at different levels from larger standard glaciological (vertical) ice cores 7.5 cm in diameter. These samples were cooled in liquid nitrogen and placed in cryotubes, were stored in the same dry shipping container, and sent to the SEM facility. In the laboratory, the samples were sputter coated with platinum and imaged by a low-temperature SEM. To image the firn and glacier ice samples, the cores were fractured in liquid nitrogen, attached to a specimen holder, and then imaged. While light microscope images of snow and ice are difficult to interpret because of internal reflection and refraction, the SEM images provide a clear and unique view of the surface of the samples because they are generated from electrons emitted or reflected only from the surface of the sample. In addition, the SEM has a great depth of field with a wide range of magnifying capabilities. The resulting images clearly show the individual grains of the seasonal snowpack and the bonding between the snow grains. Images of firn show individual ice crystals, the bonding between the crystals, and connected air spaces. Images of glacier ice show a crystal structure on a scale of 1-2 mm which is considerably smaller than the expected crystal size. Microscopic air bubbles, less than 15 ??m in diameter, clearly marked the boundaries between these crystal-like features. The life forms associated with the glacier were easily imaged and studied. The low-temperature SEM sample collecting and handling methods proved to be operable in the field; the SEM analysis is applicable to glaciological studies and reveals details unattainable by conventional light microscopic methods.Low temperature scanning electron microscopy (SEM) was used to observe metamorphosed snow, glacial firn, and glacial ice obtained from South Cascade Glacier in Washington State, USA. Biotic samples consisting of algae and ice worms were also collected and imaged. The SEM images provide a clear and unique view of the surface of the samples because they are generated from electrons emitted or reflected only from the surface of the sample. The SEM has a great depth of field with a wide range of magnifying capabilities.

  3. (abstract) Examining Sea Ice SAR Signatures in the Arctic

    NASA Technical Reports Server (NTRS)

    Holt, Benjamin

    1993-01-01

    This research examines the seasonal changes of the sea ice cover in the Arctic Basin as it responds to atmospheric and oceanic conditions. Monitoring this process provides a means of determining the onset and extent of the annual seasonal stages, which is thought to be an indicator for detecting climate change in the polar regions. Much of the response of sea ice to seasonal conditions results in changes in the phase of water (both in the ice and snow cover), surface roughness, and internal properties such as air bubbles. Imagery from SAR has proven to be an important tool for revealing these changes since radar backscatter is affected by both surface roughness and dielectric properties of water and salt. The major ice types and ice features may have unique SAR backscatter signatures because of the inherent variations in surface roughness, salinity, and internal properties in each category.

  4. Export of Algal Biomass from the Melting Arctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Boetius, Antje; Albrecht, Sebastian; Bakker, Karel; Bienhold, Christina; Felden, Janine; Fernández-Méndez, Mar; Hendricks, Stefan; Katlein, Christian; Lalande, Catherine; Krumpen, Thomas; Nicolaus, Marcel; Peeken, Ilka; Rabe, Benjamin; Rogacheva, Antonina; Rybakova, Elena; Somavilla, Raquel; Wenzhöfer, Frank; aff1

    2013-03-01

    In the Arctic, under-ice primary production is limited to summer months and is restricted not only by ice thickness and snow cover but also by the stratification of the water column, which constrains nutrient supply for algal growth. Research Vessel Polarstern visited the ice-covered eastern-central basins between 82° to 89°N and 30° to 130°E in summer 2012, when Arctic sea ice declined to a record minimum. During this cruise, we observed a widespread deposition of ice algal biomass of on average 9 grams of carbon per square meter to the deep-sea floor of the central Arctic basins. Data from this cruise will contribute to assessing the effect of current climate change on Arctic productivity, biodiversity, and ecological function.

  5. Export of algal biomass from the melting Arctic sea ice.

    PubMed

    Boetius, Antje; Albrecht, Sebastian; Bakker, Karel; Bienhold, Christina; Felden, Janine; Fernández-Méndez, Mar; Hendricks, Stefan; Katlein, Christian; Lalande, Catherine; Krumpen, Thomas; Nicolaus, Marcel; Peeken, Ilka; Rabe, Benjamin; Rogacheva, Antonina; Rybakova, Elena; Somavilla, Raquel; Wenzhöfer, Frank

    2013-03-22

    In the Arctic, under-ice primary production is limited to summer months and is restricted not only by ice thickness and snow cover but also by the stratification of the water column, which constrains nutrient supply for algal growth. Research Vessel Polarstern visited the ice-covered eastern-central basins between 82° to 89°N and 30° to 130°E in summer 2012, when Arctic sea ice declined to a record minimum. During this cruise, we observed a widespread deposition of ice algal biomass of on average 9 grams of carbon per square meter to the deep-sea floor of the central Arctic basins. Data from this cruise will contribute to assessing the effect of current climate change on Arctic productivity, biodiversity, and ecological function. PMID:23413190

  6. Annual sea ice. An air-sea gas exchange moderator

    SciTech Connect

    Gosink, T.A.; Kelley, J.J.

    1982-01-01

    Arctic annual sea ice, particularly when it is relatively warm (> -15/sup 0/C) permits significant gas exchange between the sea and air throughout the entire year. Sea ice, particularly annual sea ice, differs from freshwater ice with respect to its permeability to gases. The presence of brine allows for significant air-sea-ice exchange of CO/sub 2/ throughout the winter, which may significantly affect the global carbon dioxide balance. Other trace gases are also noted to be enriched in sea ice, but less is known about their importance to air-sea-interactions at this time. Both physical and biological factors cause and modify evolution of gases from the surface of sea ice. Quantitative and qualitative descriptions of the nature and physical behavior of sea ice with respect to brine and gases are discussed.

  7. A mechanism for biologically induced iodine emissions from sea ice

    NASA Astrophysics Data System (ADS)

    Saiz-Lopez, A.; Blaszczak-Boxe, C. S.; Carpenter, L. J.

    2015-09-01

    Ground- and satellite-based measurements have reported high concentrations of iodine monoxide (IO) in coastal Antarctica. The sources of such a large iodine burden in the coastal Antarctic atmosphere remain unknown. We propose a mechanism for iodine release from sea ice based on the premise that micro-algae are the primary source of iodine emissions in this environment. The emissions are triggered by the biological production of iodide (I-) and hypoiodous acid (HOI) from micro-algae (contained within and underneath sea ice) and their diffusion through sea-ice brine channels, ultimately accumulating in a thin brine layer (BL) on the surface of sea ice. Prior to reaching the BL, the diffusion timescale of iodine within sea ice is depth-dependent. The BL is also a vital component of the proposed mechanism as it enhances the chemical kinetics of iodine-related reactions, which allows for the efficient release of iodine to the polar boundary layer. We suggest that iodine is released to the atmosphere via three possible pathways: (1) emitted from the BL and then transported throughout snow atop sea ice, from where it is released to the atmosphere; (2) released directly from the BL to the atmosphere in regions of sea ice that are not covered with snowpack; or (3) emitted to the atmosphere directly through fractures in the sea-ice pack. To investigate the proposed biology-ice-atmosphere coupling at coastal Antarctica we use a multiphase model that incorporates the transport of iodine species, via diffusion, at variable depths, within brine channels of sea ice. Model simulations were conducted to interpret observations of elevated springtime IO in the coastal Antarctic, around the Weddell Sea. While a lack of experimental and observational data adds uncertainty to the model predictions, the results nevertheless show that the levels of inorganic iodine (i.e. I2, IBr, ICl) released from sea ice through this mechanism could account for the observed IO concentrations during this timeframe. The model results also indicate that iodine may trigger the catalytic release of bromine from sea ice through phase equilibration of IBr. Considering the extent of sea ice around the Antarctic continent, we suggest that the resulting high levels of iodine may have widespread impacts on catalytic ozone destruction and aerosol formation in the Antarctic lower troposphere.

  8. Estimation of Antarctic sea ice properties using surface and space borne data

    NASA Astrophysics Data System (ADS)

    Ozsoy Cicek, Burcu

    Sea ice is a fundamental component of the Earth's systems that cannot be ignored in the large scale environmental predictions of future climate conditions. Sea ice is a complex material and has major influences on global climate with its large maximum extent and seasonal change. In this research, remote sensing validation based on comparisons with surface based data has been done for quantitative monitoring of the ice properties. Various satellite products consisting of passive microwave, active microwave, and high resolution visible imagery were used and compared with in-situ measurements collected during scientific Antarctic cruises, conducted during International Polar Year (IPY) 2007--2008. This data used to provide a quantifiable method for observing sea ice, from all regions of the Antarctic sea ice zone to develop relationships that test existing remote sensing algorithms, evaluate alternative algorithms and provide error estimates on sea ice thickness derived from existing algorithms. Chapter 2 presents the comparison of ice extent/ice edge data from the NIC and the AMSR-E (Advanced Microwave Scanning Radiometer-Earth Observing System) passive microwave products using the Antarctic Sea Ice Process and Climate (ASPeCt) ship observations from the Oden expedition in December 2006 as ground truth to verify the two products during Antarctic summer. Ice edge location comparison has also been made between the two data sets, ship ice observations and NIC daily ice edge products. NIC analyses rely more heavily on high resolution satellite imagery such as active radar and visible imagery when visibility (clouds) allows. From these comparisons, a quantitative estimate of the differences in summer ice extent between the two remotely obtained products, AMSR-E and NIC ice edge, over the larger West Antarctic sea ice zone, has been obtained. Chapter 3 evaluates the comparison of ASPeCt ship based observations (conducted during Sea Ice Mass Balance in the Antarctic (SIMBA) 2007 Antarctic cruise) with coincident satellite active and passive microwave data. We combined visual ship-based observations of sea-ice and snow properties during SIMBA with coincident active and passive microwave satellite data with the aims to (a) derive typical radar backscatter ranges for observed sea-ice types and ice type mixtures, (b) improve our knowledge about the radar backscatter of different ice types in the Bellingshausen Sea at early-middle spring, (c) interpret AMSR-E snow depth over these ice types, and (d) identify the potential of the investigated active microwave signatures for a synergy with AMSR-E data to eventually improve the snow depth retrieval. Chapter 4 presents the validation of remote sensing measurements of ice extent and concentration with ASPeCt ship-based ice observations, conducted during the SIMBA and the Sea Ice Physics and Ecosystem eXperiment (SIPEX) International Polar Year (IPY) cruises (Sept--Oct 2007). First, the total sea ice cover around the entire continent was determined for 2007--2008 from Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) passive microwave and National Ice Center (NIC) charts. Second, Antarctic Sea Ice Processes and Climate (ASPeCt) ship observations from the SIMBA and SIPEX expeditions in the austral end of winter--beginning of spring 2007 are used as ground truth to verify the AMSR-E sea ice concentration product provided by both the Enhanced NASA Team Algorithm (NT2) and Bootstrap Basic Algorithm (BBA). Chapter 5 presents supplemental analysis related to the baseline thickness of Antarctic sea ice on a circumpolar basis from field measurements. In this part, our objectives were (1) Develop statistical relationships between surface elevation (snow freeboard), ice elevation (ice freeboard) and mean sea ice thickness using previous and newly obtained Antarctic sea ice profiles and examine these relationships for any consistent regional trends, (2) Derive sea ice thickness from profile elevations, using buoyancy equation, to determine error estimates compared to measured thic

  9. Improved Upper Ocean/Sea Ice Modeling in the GISS GCM for Investigating Climate Change

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This project built on our previous results in which we highlighted the importance of sea ice in overall climate sensitivity by determining that for both warming and cooling climates, when sea ice was not allowed to change, climate sensitivity was reduced by 35-40%. We also modified the GISS 8 deg x lO deg atmospheric GCM to include an upper-ocean/sea-ice model involving the Semtner three-layer ice/snow thermodynamic model, the Price et al. (1986) ocean mixed layer model and a general upper ocean vertical advection/diffusion scheme for maintaining and fluxing properties across the pycnocline. This effort, in addition to improving the sea ice representation in the AGCM, revealed a number of sensitive components of the sea ice/ocean system. For example, the ability to flux heat through the ice/snow properly is critical in order to resolve the surface temperature properly, since small errors in this lead to unrestrained climate drift. The present project, summarized in this report, had as its objectives: (1) introducing a series of sea ice and ocean improvements aimed at overcoming remaining weaknesses in the GCM sea ice/ocean representation, and (2) performing a series of sensitivity experiments designed to evaluate the climate sensitivity of the revised model to both Antarctic and Arctic sea ice, determine the sensitivity of the climate response to initial ice distribution, and investigate the transient response to doubling CO2.

  10. Improved Upper Ocean/Sea Ice Modeling in the GISS GCM for Investigating Climate Change

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This project built on our previous results in which we highlighted the importance of sea ice in overall climate sensitivity by determining that for both warming and cooling climates, when sea ice was not allowed to change, climate sensitivity was reduced by 35-40%. We also modified the Goddard Institute for Space Studies (GISS) 8 deg x lO deg atmospheric General Circulation Model (GCM) to include an upper-ocean/sea-ice model involving the Semtner three-layer ice/snow thermodynamic model, the Price et al. (1986) ocean mixed layer model and a general upper ocean vertical advection/diffusion scheme for maintaining and fluxing properties across the pycnocline. This effort, in addition to improving the sea ice representation in the AGCM, revealed a number of sensitive components of the sea ice/ocean system. For example, the ability to flux heat through the ice/snow properly is critical in order to resolve the surface temperature properly, since small errors in this lead to unrestrained climate drift. The present project, summarized in this report, had as its objectives: (1) introducing a series of sea ice and ocean improvements aimed at overcoming remaining weaknesses in the GCM sea ice/ocean representation, and (2) performing a series of sensitivity experiments designed to evaluate the climate sensitivity of the revised model to both Antarctic and Arctic sea ice, determine the sensitivity of the climate response to initial ice distribution, and investigate the transient response to doubling CO2.

  11. A physical algorithm to measure sea ice concentration from passive microwave remote sensing data

    NASA Astrophysics Data System (ADS)

    Tikhonov, V. V.; Repina, I. A.; Raev, M. D.; Sharkov, E. A.; Ivanov, V. V.; Boyarskii, D. A.; Alexeeva, T. A.; Komarova, N. Yu.

    2015-10-01

    A conceptually new algorithm of sea ice concentration retrieval in polar regions from satellite microwave radiometry data is discussed. The algorithm design favorably contrasts with that of known modern algorithms. Its design is based on a physical emission model of the "sea surface - sea ice - snow cover - atmosphere" system. No tie-points are used in the algorithm. All the calculation expressions are derived from theoretical modeling. The design of the algorithm minimizes the impact of atmospheric variability on sea ice concentration retrieval. Beside estimating sea ice concentration, the algorithm makes it possible to indicate ice areas with melting snow and melt ponds. The algorithm is simple to use, no complicated or time consuming calculations are involved.

  12. Sea Ice Rheology Daniel L. Feltham

    E-print Network

    Feltham, Daniel

    Sea Ice Rheology Daniel L. Feltham Centre for Polar Observation and Modelling, Department of Earth-4189/08/0115-0091$20.00 Key Words Arctic, Antarctic, climate model Abstract The polar oceans of Earth are covered by sea ice. On timescales much greater than a day, the motion and deformation of the sea ice cover (i.e., its dynamics

  13. Detection of ice crust formation on snow with satellite data

    NASA Astrophysics Data System (ADS)

    Bartsch, Annett; Bulygina, Olga N.; Kumpula, Timo; Forbes, Bruce; Stammler, Florian

    2010-05-01

    Short term thawing of the snow surface and subsequent refreeze can lead to the formation of ice crusts. These events are related to specific meteorological conditions such us rain-on-snow events and/or temporary increase of air temperature above zero degree Celsius. The structure change in the snow pack has adverse effect especially on wild life and also the local community related to reindeer herding. Active microwave satellite data can be used to monitor changes of snow related to thawing. So far they have been mostly employed for spring thaw detection. Coarse spatial resolution sensors such as scatterometer feature short revisit intervals. Seawinds QuikScat (Ku-band, 25km, 1999-2009) acquired data several times per day at high latitudes. This allows precise detection of the timing of thaw events. Also the change of structure in the snow itself impacts the backscatter. Values increase significantly. A method has been developed to monitor these events at high latitudes (>60°N) on circumpolar scale. Validation is carried out based on air temperature records and snow course data over Northern Eurasia. Events during midwinter of the last nine years (November - February 2000/1 - 2008/9) have been frequent in northern Europe, European Russia and Alaska. They have occurred up to once a year in central Siberia, the Russian Far East and most of northern Canada. Monitoring is important as such events are discussed in relation to climate change especially over Northern Eurasia.

  14. Wind waves in ice-free areas of Arctic seas.

    NASA Astrophysics Data System (ADS)

    Golubkin, Pavel; Chapron, Bertrand; Kudryavtsev, Vladimir

    Wind-generated waves in Kara, Laptev and East Siberian Seas are investigated using altimeter data from ENVISAT and SARAL-AltiKa. Only the “isolated” ice-free areas had been selected for analysis. In this case wind seas can be treated as pure wind-generated waves without any contamination by the swell. The isolated ice-free areas are identified using National Snow & Ice Data Center (NSIDC) ice concentration data generated from brightness temperatures derived from Special Sensor Microwave/Imager (SSM/I) and Special Sensor Microwave Imager/Sounder (SSMIS) on board the Defense Meteorological Satellite Program (DMSP) F13 and F17 satellites, respectively. The altimeter data, both significant wave height (SWH) and wind speed which were accompanied with ASCAT scatterometer wind velocity field (since 2007), have been selected for these areas in the time period 2002-2013. This data set is analyzed in terms of dimensionless SWH and dimensionless ice-free area. Either of these quantities is scaled using “standard” dimension analysis based on wind speed and gravity acceleration. Universal empirical dependences of dimensionless SWH on dimensionless ice-free areas are established. At smallest ice-free areas they are consistent with known universal dependences for wind wave generation at fetch limited conditions. At the largest ice-free areas the established dependences are consistent with field data for the open ocean conditions. Impact of climate change and ice melting in the Arctic areas on wind seas is discussed.

  15. The Sea Ice Board Game

    ERIC Educational Resources Information Center

    Bertram, Kathryn Berry

    2008-01-01

    The National Science Foundation-funded Arctic Climate Modeling Program (ACMP) provides "curriculum resource-based professional development" materials that combine current science information with practical classroom instruction embedded with "best practice" techniques for teaching science to diverse students. The Sea Ice Board Game, described…

  16. Surveying Arctic Sea Ice

    USGS Multimedia Gallery

    Two U.S. Coast Guard members are being transported by crane from U.S. Coast Guard Cutter Healy onto a piece of multi-year ice. This was during a scientific expedition to map the Arctic seafloor. The expedition was a joint effort using two ships, Healy and the Canadian Coast Guard Ship Louis S. St. L...

  17. 30 CFR 57.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Snow and ice on walkways and travelways. 57... MINES Travelways and Escapeways Travelways-Surface and Underground § 57.11016 Snow and ice on walkways and travelways. Regularly used walkways and travelways shall be sanded, salted, or cleared of snow...

  18. 30 CFR 57.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Snow and ice on walkways and travelways. 57... MINES Travelways and Escapeways Travelways-Surface and Underground § 57.11016 Snow and ice on walkways and travelways. Regularly used walkways and travelways shall be sanded, salted, or cleared of snow...

  19. 30 CFR 57.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Snow and ice on walkways and travelways. 57... MINES Travelways and Escapeways Travelways-Surface and Underground § 57.11016 Snow and ice on walkways and travelways. Regularly used walkways and travelways shall be sanded, salted, or cleared of snow...

  20. 30 CFR 57.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Snow and ice on walkways and travelways. 57... MINES Travelways and Escapeways Travelways-Surface and Underground § 57.11016 Snow and ice on walkways and travelways. Regularly used walkways and travelways shall be sanded, salted, or cleared of snow...

  1. 30 CFR 57.11016 - Snow and ice on walkways and travelways.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Snow and ice on walkways and travelways. 57... MINES Travelways and Escapeways Travelways-Surface and Underground § 57.11016 Snow and ice on walkways and travelways. Regularly used walkways and travelways shall be sanded, salted, or cleared of snow...

  2. The U.S. Navy's Emerging Sea Ice Prediction Capabilities

    NASA Astrophysics Data System (ADS)

    Allard, Richard; Campbell, Tim; Hebert, David; Metzger, E. Joseph; Posey, Pamela; Wallcraft, Alan; Smedstad, Ole Martin; Gaberšek, Saša; Jin, Yi; Wang, Shouping

    2014-05-01

    The U.S. Navy's regional and global coupled sea ice modeling activities are described. The Arctic Cap Nowcast Forecast System (ACNFS) is a 3.5 km coupled sea ice-ocean model that produces 7 day forecasts of the Arctic sea ice state in all ice covered areas in the northern hemisphere (poleward of 40°N). The ocean component is the HYbrid Coordinate Ocean Model (HYCOM) and is coupled to the Los Alamos National Laboratory Community Ice CodE (CICE) via the Earth System Modeling Framework (ESMF). The ocean and sea ice models are run in an assimilative cycle with the Navy's Coupled Ocean Data Assimilation (NCODA) system. The ACNFS was transitioned to operations at the Naval Oceanographic Office in 2013 to serve its customer, the National Ice Center. The Global Ocean forecast System (GOFS3.1) is essentially an extension of ACNFS to the globe at 1/12° (equatorial) resolution, still 3.5 km in the Arctic, and it will provide sea ice predictions for the Arctic and Antarctic. Testing and validation is underway and an operational transition is planned for 2015, when GOFS3.1 will replace the ACNFS. A relocatable regional capability is being developed by coupling CICE to the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS). This new system will have an advanced snow-ice albedo representation and produce coupled forecasts out to 7-10 days with resolutions for the atmosphere and sea ice models at 1-3 km. Examples of these emerging capabilities will be presented.

  3. Finite-Element Sea Ice Model (FESIM), version 2

    NASA Astrophysics Data System (ADS)

    Danilov, S.; Wang, Q.; Timmermann, R.; Iakovlev, N.; Sidorenko, D.; Kimmritz, M.; Jung, T.; Schröter, J.

    2015-06-01

    The Finite-Element Sea Ice Model (FESIM), used as a component of the Finite-Element Sea ice Ocean Model, is presented. Version 2 includes the elastic-viscous-plastic (EVP) and viscous-plastic (VP) solvers and employs a flux corrected transport algorithm to advect the ice and snow mean thicknesses and concentration. The EVP part also includes a modified approach proposed recently by Bouillon et al. (2013), which is characterized by an improved stability compared to the standard EVP approach. The model is formulated on unstructured triangular meshes. It assumes a collocated placement of ice velocities, mean thicknesses and concentration at mesh vertices, and relies on piecewise-linear (P1) continuous elements. Simple tests for the modified EVP and VP solvers are presented to show that they may produce very close results provided the number of iterations is sufficiently high.

  4. Finite-Element Sea Ice Model (FESIM), version 2

    NASA Astrophysics Data System (ADS)

    Danilov, S.; Wang, Q.; Timmermann, R.; Iakovlev, N.; Sidorenko, D.; Kimmritz, M.; Jung, T.; Schröter, J.

    2015-02-01

    The Finite-Element Sea-Ice Model, used as a component of the Finite-Element Sea ice Ocean Model, is presented. Version 2 includes the elastic-viscous-plastic (EVP) and viscous-plastic (VP) solvers and employs a flux corrected transport algorithm to advect the ice and snow mean thicknesses and concentration. The EVP part also includes a modified approach proposed recently by Bouillon et al., which is characterized by an improved stability compared to the standard EVP approach. The model is formulated on unstructured triangular meshes. It assumes a collocated placement of ice velocities, mean thicknesses and concentration at mesh vertices, and relies on a piecewise-linear (P1) continuous elements. Simple tests for the modified EVP and VP solvers are presented to show that they may produce very close results provided the number of iterations is sufficiently high.

  5. Creating Arctic Sea Ice Protected Areas?

    NASA Astrophysics Data System (ADS)

    Pfirman, S.; Hoff, K.; Temblay, B.; Fowler, C.

    2008-12-01

    As Arctic sea ice retreats and the Northwest Passage and Northern Sea Route open, the Arctic will experience more extensive human activity than it has ever encountered before. New development will put pressure on a system already struggling to adapt to a changing environment. In this analysis, locations are identified within the Arctic that could be protected from resource extraction, transportation and other development in order to create refuges and protect remnants of sea ice habitat, as the Arctic transitions to ice-free summer conditions. Arctic sea ice forms largely along the Siberian and Alaskan coasts and is advected across the North Pole towards Fram Strait, the Canadian Archipelago and the Barents Sea. In addition to the future loss of ice itself, contaminants entrained in sea ice in one part of the ocean can affect other regions as the ice drifts. Using observations and models of sea ice origins, trajectories and ages, we track sea ice from its origins towards marginal ice zones, mapping pathways and termination locations. Critical sea ice source areas and collection regions are identified with the goal of aiding in the protection of the remaining Arctic sea ice habitat for as long as possible.

  6. Skillful prediction of Barents Sea ice cover

    NASA Astrophysics Data System (ADS)

    Onarheim, Ingrid H.; Eldevik, Tor; Årthun, Marius; Ingvaldsen, Randi B.; Smedsrud, Lars H.

    2015-07-01

    A main concern of present climate change is the Arctic sea ice cover. In wintertime, its observed variability is largely carried by the Barents Sea. Here we propose and evaluate a simple quantitative and prognostic framework based on first principles and rooted in observations to predict the annual mean Barents Sea ice cover, which variance is carried by the winter ice (96%). By using observed ocean heat transport and sea ice area, the proposed framework appears skillful and explains 50% of the observed sea ice variance up to 2 years in advance. The qualitative prediction of increase versus decrease in ice cover is correct 88% of the time. Model imperfections can largely be diagnosed from simultaneous meridional winds. The framework and skill are supported by a 60 year simulation from a regional ice-ocean model. We particularly predict that the winter sea ice cover for 2016 will be slightly less than 2015.

  7. Heated abrasives on snow and ice covered roads

    NASA Astrophysics Data System (ADS)

    Swanson, H. N.

    1982-08-01

    The effectiveness of using heated abrasives versus cold, wet abrasives in snow and ice control was studied. It was concluded that: (1) sand is blown or whipped off the road only a small percentage of the time under specific conditions; (2) the traveling public adjusts to driving conditions rather well in the Colorado Rockies; and (3) covered sand sheds would be a definite advantage but should have mechanisms for filling from the top.

  8. The Effect of Atmosphere-Snow-Ice-Ocean Coupling on Hexachlorocyclohexane Pathways within the Arctic Marine Environment

    NASA Astrophysics Data System (ADS)

    Pucko, Monika Agnieszka

    2011-07-01

    The importance of the cryosphere, and of sea ice in particular, for contaminant transport and redistribution in the Arctic was pointed out in the literature. However, studies on contaminants in sea ice are scarce, and entirely neglect the sea ice geophysical and thermodynamic characteristics as well as interactions between various cryospheric compartments. This thesis addresses those gaps. Ice formation was shown to have a significant concentrating impact on the levels of HCHs in the water just beneath the ice. Both geophysical and thermodynamic conditions in sea ice were shown to be crucial in understanding pathways of accumulation or rejection of HCHs. Although HCH burden in the majority of the ice column remains locked throughout most of the season until the early spring, upward migration of brine from the ice to the snow in the winter has an effect on levels of HCHs in the snow by up to 50 %. In the spring, when snow melt water percolates into the ice delivering HCHs to the upper ocean via desalination by flushing, levels of HCHs in the ice can increase by up to 2 %-18 % and 4 %-32 % for ?- and ?-HCH, respectively. Brine contained within sea ice currently exhibits the highest HCH concentrations in any abiotic Arctic environment, exceeding under-ice water concentrations by a factor of 3 in the spring. This circumstance suggests that the brine ecosystem has been, and continues to be, the most exposed to HCHs. ?-HCH levels were shown to decrease rapidly in the last two decades in the Polar Mixed Layer (PML) and the Pacific Mode Layer (PL) of the Beaufort Sea due to degradation. If the rate of degradation does not change in the near future, the majority of ?-HCH could be eliminated from the Beaufort Sea by 2020, with concentrations in 2040 dropping to < 0.006 ng/L and < 0.004 ng/L in the PML and the PL, respectively. Elimination of ?-HCH from sea water takes significantly longer than from the atmosphere, with a lag of approximately two decades.

  9. Sea Ice Characteristics and the Open-Linked Data World

    NASA Astrophysics Data System (ADS)

    Khalsa, S. J. S.; McGuinness, D. L.; Duerr, R.; Pulsifer, P. L.; Fox, P. A.; Thompson, C.; Yan, R.

    2014-12-01

    The audience for sea ice data sets has broadened dramatically over the past several decades. Initially the National Snow and Ice Data Center (NSIDC) sea ice products were used primarily by sea ice specialists. However, now they are in demand by researchers in many different domains and some are used by the public. This growth in the number and type of users has presented challenges to content providers aimed particularly at supporting interdisciplinary and multidisciplinary data use. In our experience, it is generally insufficient to simply make the data available as originally formatted. New audiences typically need data in different forms; forms that meet their needs, that work with their specific tools. Moreover, simple data reformatting is rarely enough. The data needs to be aggregated, transformed or otherwise converted into forms that better serve the needs of the new audience. The Semantic Sea Ice Interoperability Initiative (SSIII) is an NSF-funded research project aimed at making sea ice data more useful to more people using semantic technologies. The team includes domain and science data experts as well as knowledge representation and linked data experts. Beginning with a series of workshops involving members of the operations, sea ice research and modeling communities, as well as members of local communities in Alaska, a suite of ontologies describing the physical characteristics of sea ice have been developed and used to provide one of NSIDC's data sets, the operational Arctic sea ice charts obtained from the Canadian Ice Center, as open-linked data. These data extend nearly a decade into the past and can now be queried either directly through a publicly available SPARQL end point (for those who are familiar with open-linked data) or through a simple Open Geospatial Consortium (OGC) standards map-based query tool. Questions like "What were the characteristics (i.e., sea ice concentration, form and stage of development) of the sea ice in the region surrounding my ship/polar bear on date X?" can now be answered. This service may be of interest within the broad polar community - especially those who already are familiar with either open-linked data or OGC services. We seek feedback, collaborators, and users.

  10. Inter-annual and Seasonal Variability of Sea Ice Thickness North of Alert, Ellesmere Island and in the Lincoln Sea

    NASA Astrophysics Data System (ADS)

    Lange, B. A.; Haas, C.; Hendricks, S.; Beckers, J.

    2009-12-01

    Satellite observations demonstrate a decreasing summer Arctic sea ice extent over the past ~37 years, as well as a smaller perennial sea ice zone, with a significantly accelerated decline in the last decade. Recent ice extent observations are significantly lower than predicted by any model employed by the Intergovernmental Panel on Climate Change (IPCC). The disagreement of the modeled and observed results, along with the large variability of model results, can be in part attributed to a lack of consistent and long term sea ice mass balance observations for the High Arctic. This study presents aerial sea-ice thickness data north of Alert, Nunavut, during April-May of 2004-2009 (excluding 2006), acquired with airplane and helicopter (HEM) electromagnetic induction systems. These observations are a unique 5 year time series of sea-ice thickness and the most extensive observations of multi-year sea ice thickness in this region of the Arctic Ocean. These data help to better understand the interannual variability of ice thickness and ice mass balance in the perennial ice zone. Results demonstrate thinning of sea ice from 2004 to 2008. Ground based snow and ice thickness surveys of ice floes in the Lincoln Sea were conducted in May 2009. Furthermore we deployed GPS buoys on these floes in order to revisit them and repeat the ground based surveys, in August 2009, during the CCG Larsen’s passage through Nares Strait. In addition, HEM sea-ice thickness profiles will be conducted along the cruise track and will be presented with the survey observations and HEM thickness data from May 2009 in order to describe the seasonal variability of sea ice exported from the Lincoln Sea into Nares Strait. All observations will be complemented with NCEP meteorological data to help characterize the observed results of the study. Operation of the HEM bird (August 2009), from the CCGS Henry Larsen Icebreaker, in Nares Strait over validation sites.

  11. CBSIT 2009: Airborne Validation of Envisat Radar Altimetry and In Situ Ice Camp Measurements Over Arctic Sea Ice

    NASA Technical Reports Server (NTRS)

    Connor, Laurence; Farrell, Sinead; McAdoo, David; Krabill, William; Laxon, Seymour; Richter-Menge, Jacqueline; Markus, Thorsten

    2010-01-01

    The past few years have seen the emergence of satellite altimetry as valuable tool for taking quantitative sea ice monitoring beyond the traditional surface extent measurements and into estimates of sea ice thickness and volume, parameters that arc fundamental to improved understanding of polar dynamics and climate modeling. Several studies have now demonstrated the use of both microwave (ERS, Envisat/RA-2) and laser (ICESat/GLAS) satellite altimeters for determining sea ice thickness. The complexity of polar environments, however, continues to make sea ice thickness determination a complicated remote sensing task and validation studies remain essential for successful monitoring of sea ice hy satellites. One such validation effort, the Arctic Aircraft Altimeter (AAA) campaign of2006. included underflights of Envisat and ICESat north of the Canadian Archipelago using NASA's P-3 aircraft. This campaign compared Envisat and ICESat sea ice elevation measurements with high-resolution airborne elevation measurements, revealing the impact of refrozen leads on radar altimetry and ice drift on laser altimetry. Continuing this research and validation effort, the Canada Basin Sea Ice Thickness (CBSIT) experiment was completed in April 2009. CBSIT was conducted by NOAA. and NASA as part of NASA's Operation Ice Bridge, a gap-filling mission intended to supplement sea and land ice monitoring until the launch of NASA's ICESat-2 mission. CBIST was flown on the NASA P-3, which was equipped with a scanning laser altimeter, a Ku-band snow radar, and un updated nadir looking photo-imaging system. The CB5IT campaign consisted of two flights: an under flight of Envisat along a 1000 km track similar to that flown in 2006, and a flight through the Nares Strait up to the Lincoln Sea that included an overflight of the Danish GreenArc Ice Camp off the coast of northern Greenland. We present an examination of data collected during this campaign, comparing airborne laser altimeter measurements with (1) Envisat RA-2 returns retracked optimally for sea ice and (2) in situ measurements of sea ice thickness and snow depth gathered from ice camp surveys. Particular attention is given to lead identification and classification using the continuous photo-imaging system along the Envisat underflight as well as the performance of the snow radar over the ice camp survey lines.

  12. Sea ice, climate, and multiscale composites

    NASA Astrophysics Data System (ADS)

    Golden, Kenneth

    2014-03-01

    In September of 2012, the area of the Arctic Ocean covered by sea ice reached its lowest level ever recorded in more than three decades of satellite measurements. In fact, compared to the 1980's and 1990's, this represents a loss of more than half of the summer Arctic sea ice pack. While global climate models generally predict sea ice declines over the 21st century, the precipitous losses observed so far have significantly outpaced most projections. I will discuss how mathematical models of composite materials and statistical physics are being used to study key sea ice processes and advance how sea ice is represented in climate models. This work is helping to improve projections of the fate of Earth's ice packs, and the response of polar ecosystems. A brief video of a recent Antarctic expedition where sea ice properties were measured will be shown. Supported by NSF and ONR.

  13. Drones application on snow and ice surveys in alpine areas

    NASA Astrophysics Data System (ADS)

    La Rocca, Leonardo; Bonetti, Luigi; Fioletti, Matteo; Peretti, Giovanni

    2015-04-01

    First results from Climate change are now clear in Europe, and in Italy in particular, with the natural disasters that damaged irreparably the territory and the habitat due to extreme meteorological events. The Directive 2007/60/EC highlight that an "effective natural hazards prevention and mitigation that requires coordination between Member States above all on natural hazards prevention" is necessary. A climate change adaptation strategy is identified on the basis of the guidelines of the European Community program 2007-2013. Following the directives provided in the financial instrument for civil protection "Union Civil Protection Mechanism" under Decision No. 1313/2013 / EU of the European Parliament and Council, a cross-cutting approach that takes into account a large number of implementation tools of EU policies is proposed as climate change adaptation strategy. In last 7 years a network of trans-Alpine area's authorities was created between Italy and Switzerland to define an adaptive strategy on climate change effects on natural enviroment based on non structural remedies. The Interreg IT - CH STRADA Project (STRategie di ADAttamento al cambiamento climatico) was born to join all the non structural remedies to climate change effects caused by snow and avalanches, on mountain sources, extreme hydrological events and to manage all transnational hydrological resources, involving all stakeholders from Italy and Switzerland. The STRADA project involved all civil protection authorities and all research centers in charge of snow, hydrology end civil protection. The Snow - meteorological center of the Regional Agency for Environment Protection (CNM of ARPA Lombardia) and the Civil Protection of Lombardy Region created a research team to develop tools for avalanche prediction and to observe and predict snow cover on Alpine area. With this aim a lot of aerial photo using Drone as been performed in unusual landscape. Results of all surveys were really interesting on a scientific point of view. All flight was performed by remote controlled aero models with high resolution camera. Aero models were able to take off and to ground on snow covered or icy surfaces since the specific aerodynamic configuration and specific engine used to. All winter surveys were executed flying low to obtain a tridimensional reconstruction of an High resolution Digital Elevation Model (DEM) of snow cover and ice cover and on summer as been developed the DEM were snow amass in the maximum avalanche risk period. The difference between winter and summer DEM (difference between two point clouds) let to individuate the snow depth, and it was used as input data for the snow avalanche model for the Aprica site (Bergamo - Italy).

  14. A Novel and Low Cost Sea Ice Mass Balance Buoy.

    NASA Astrophysics Data System (ADS)

    Jackson, Keith; Meldrum, David; Wilkinson, Jeremy; Maksym, Ted; Beckers, Justin; Haas, Christian

    2013-04-01

    Understanding of sea ice mass balance processes requires continuous monitoring of the seasonal evolution of ice thickness. While autonomous ice mass balance buoys (IMBs) deployed over the past two decades have contributed to our understanding of ice growth and decay processes, deployment has been limited, in part, by the cost of such systems. Routine, basin-wide monitoring of the ice cover is realistically achievable through a network of reliable and affordable autonomous instrumentation. We describe the development of a novel autonomous platform and sensor that replaces the traditional thermistors string for monitoring temperature profiles in the ice and snow using a chain of inexpensive digital temperature chip sensors linked by a single-wire data bus. By incorporating a heating element on each sensor, the instrument is capable of resolving material interfaces (e.g. air-snow and ice-ocean boundaries) even under isothermal conditions. The instrument is small, low-cost and easy to deploy. Field and laboratory tests of the sensor chain demonstrate that the technology can reliably resolve material boundaries to within a few centimetres and over 50 scientific deployments have been made with encouraging results. The discrimination between different media based on sensor thermal response is weak in some deployments and efforts to optimise the measurement continue.

  15. Growth of false bottoms under sea ice

    NASA Astrophysics Data System (ADS)

    Smith, Naomi; Feltham, Daniel; Flocco, Daniela

    2015-04-01

    In the summer months, melt water from the surface of Arctic sea ice can percolate through the relatively porous ice and collect at the ice-ocean interface, filling hollows in the base of the ice. These pools are called under-ice melt ponds. Freezing can occur at the interface between the fresh water and the oceanic mixed layer, forming a sheet of ice called a false bottom. These have been observed to thicken and migrate upwards over time. False bottoms insulate the true base of the sea ice from the ocean and their formation is a significant mechanism of Arctic sea ice summer growth. Current parameterisations of basal ablation of sea ice in climate models do not account for these processes, the inclusion of which could improve the accuracy of predictions of Arctic sea ice. In this poster, a one-dimensional thermodynamic model of the evolution of under-ice melt ponds and false bottoms is presented. Our aim is to develop a parameterisation of the impact of under ice melt ponds and false bottoms on basal ablation of Arctic sea ice appropriate for use in gridded climate models.

  16. Operational Products Archived at the National Snow and Ice Data Center

    NASA Astrophysics Data System (ADS)

    Fetterer, F. M.; Ballagh, L.; Gergely, K.; Kovarik, J.; Wallace, A.; Windnagel, A.

    2009-12-01

    Sea ice charts for shipping interests from the Navy/NOAA/Coast Guard National Ice Center are often laboriously produced by manually interpreting and synthesizing data from many sources, both satellite and in situ. They are generally more accurate than similar products from single sources. Upward looking sonar data from U.S. Navy submarines operating in the Arctic provides information on ice thickness. Similarly extensive data were available from no other source prior to the recently established reliability of ice thickness estimates from polar orbiting instruments like the Geoscience Laser Altimeter System (GLAS). Snow Data Assimilation System (SNODAS) products from the NOAA NWS National Operational Hydrologic Remote Sensing Center give researchers the best possible estimates of snow cover and associated variables to support hydrologic modeling and analysis for the continental U.S. These and other snow and ice data products are produced by the U.S. Navy, the NOAA National Weather Service, and other agency entities to serve users who have an operational need: to get a ship safely to its destination, for example, or to predict stream flow. NOAA supports work at NSIDC with data from operational sources that can be used for climate research and change detection. We make these products available to a new user base, by archiving operational data, making data available online, providing documentation, and fielding questions from researchers about the data. These data demand special consideration: often they are advantageous because they are available on a schedule in near real time, but their use in climate studies is problematic since many are produced with regard for ‘best now’ and without regard for time series consistency. As arctic climate changes rapidly, operational and semi-operational products have an expanding science support role to play.

  17. The convective desalination of sea ice

    E-print Network

    Rees Jones, David

    2014-07-01

    in the interstices of an ice matrix. My focus is on one of the processes by which the salt content of sea ice decreases, namely convective desalination, which is also often called gravity drainage by geophysicists. Modelling convective desalination requires...

  18. USGS and NOAA Monitor Arctic Sea Ice

    USGS Multimedia Gallery

    USGS scientist Jonathan Childs and NOAA oceanographer Pablo Clemente-Colón, also Chief Scientist of the National Ice Center, looking out on the Arctic sea ice. This was during a scientific expedition to map the Arctic seafloor....

  19. Iron and macro-nutrient concentrations in sea ice and their impact on the nutritional status of surface waters in the southern Okhotsk Sea

    NASA Astrophysics Data System (ADS)

    Kanna, Naoya; Toyota, Takenobu; Nishioka, Jun

    2014-08-01

    To elucidate the roles of sea ice in biogeochemical cycles in the Sea of Okhotsk, the concentrations of macro-nutrients (NO3 + NO2, PO4, SiO2, and NH4) and trace elements (Fe, Al) were measured in samples of sea ice, overlying snow, and seawater. The oxygen isotope ratio (?18O) in the sea ice was used to distinguish between snow ice and seawater-origin ice. Except for NH4, the macro-nutrient concentrations were lower in sea ice than in surface water in the ice-covered area. A linear relationship between salinity and concentrations of NO3 + NO2, PO4, and SiO2 in the sea ice indicated that these macro-nutrients originated mainly from seawater. The Fe concentrations in sea ice were variable and several orders of magnitude higher than those in surface water in the ice-covered area. The Fe concentrations in the sea ice were positively correlated with Al concentrations, the suggestion being that the Fe contained in the sea ice originated mainly from lithogenic mineral particles. The annual Fe flux into the surface water from sea ice melting in the southern Sea of Okhotsk was estimated to be ?740 ?mol Fe m-2 yr-1. This flux is comparable to the reported annual atmospheric Fe flux (267-929 ?mol Fe m-2 yr-1) in the western North Pacific. In spring, sea ice melting may slightly dilute macro-nutrient concentrations but increase Fe concentrations in surface water. These results suggest that sea ice may contribute to phytoplankton growth by release of Fe into the water column and have a large impact on biogeochemical cycles in the Sea of Okhotsk.

  20. Distinguishing Clouds from Ice over the East Siberian Sea, Russia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    As a consequence of its capability to retrieve cloud-top elevations, stereoscopic observations from the Multi-angle Imaging SpectroRadiometer (MISR) can discriminate clouds from snow and ice. The central portion of Russia's East Siberian Sea, including one of the New Siberian Islands, Novaya Sibir, are portrayed in these views from data acquired on May 28, 2002.

    The left-hand image is a natural color view from MISR's nadir camera. On the right is a height field retrieved using automated computer processing of data from multiple MISR cameras. Although both clouds and ice appear white in the natural color view, the stereoscopic retrievals are able to identify elevated clouds based on the geometric parallax which results when they are observed from different angles. Owing to their elevation above sea level, clouds are mapped as green and yellow areas, whereas land, sea ice, and very low clouds appear blue and purple. Purple, in particular, denotes elevations very close to sea level. The island of Novaya Sibir is located in the lower left of the images. It can be identified in the natural color view as the dark area surrounded by an expanse of fast ice. In the stereo map the island appears as a blue region indicating its elevation of less than 100 meters above sea level. Areas where the automated stereo processing failed due to lack of sufficient spatial contrast are shown in dark gray. The northern edge of the Siberian mainland can be found at the very bottom of the panels, and is located a little over 250 kilometers south of Novaya Sibir. Pack ice containing numerous fragmented ice floes surrounds the fast ice, and narrow areas of open ocean are visible.

    The East Siberian Sea is part of the Arctic Ocean and is ice-covered most of the year. The New Siberian Islands are almost always covered by snow and ice, and tundra vegetation is very scant. Despite continuous sunlight from the end of April until the middle of August, the ice between the island and the mainland typically remains until August or September.

    The Multi-angle Imaging SpectroRadiometer views almost the entire Earth every 9 days. These images were acquired during Terra orbit 12986 and cover an area of about 380 kilometers x 1117 kilometers. They utilize data from blocks 24 to 32 within World Reference System-2 path 117.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

  1. ASPECTS OF ARCTIC SEA ICE OBSERVABLE BY SEQUENTIAL PASSIVE MICROWAVE OBSERVATIONS FROM THE NIMBUS-5 SATELLITE.

    USGS Publications Warehouse

    Campbell, William J.; Gloersen, Per; Zwally, H. Jay

    1984-01-01

    Observations made from 1972 to 1976 with the Electrically Scanning Microwave Radiometer on board the Nimbus-5 satellite provide sequential synoptic information of the Arctic sea ice cover. This four-year data set was used to construct a fairly continuous series of three-day average 19-GHz passive microwave images which has become a valuable source of polar information, yielding many anticipated and unanticipated discoveries of the sea ice canopy observed in its entirety through the clouds and during the polar night. Short-term, seasonal, and annual variations of key sea ice parameters, such as ice edge position, ice types, mixtures of ice types, ice concentrations, and snow melt on the ice, are presented for various parts of the Arctic.

  2. The CReSIS Radar Suite for Measurements of the Ice Sheets and Sea Ice during Operation Ice Bridge

    NASA Astrophysics Data System (ADS)

    Leuschen, C.; Gogineni, P. S.; Allen, C.; Paden, J. D.; Hale, R.; Rodriguez-Morales, F.; Harish, A.; Seguin, S.; Arnold, E.; Blake, W.; Byers, K.; Crowe, R.; Lewis, C.; Panzer, B.; Patel, A.; Shi, L.

    2010-12-01

    The University of Kansas, Center for Remote Sensing of Ice Sheets (CReSIS) has developed a suite of radar instrumentation operating at frequencies ranging from 180 MHz to 18 GHz to monitor the major Greenland and Antarctic ice sheets at varying resolution from the surface to the bed as well as the surface topography and snow cover characteristics of sea ice. The radar suite includes a VHF multi-channel coherent radar depth sounder/imager (MCoRDS/I) to measure ice sheet thickness, internal layering, and image ice-bed interface with fine resolution; a UHF accumulation radar to measure shallow (up to 500 m) ice sheet thickness, internal layering, and accumulation rates at decimeter resolutions; an ultra-wideband “snow” radar to measure thickness of snow over sea ice and accumulation rates at centimeter scale resolution; and a wideband Ku-band altimeter to measure surface topography and accumulation layer for comparison with CryoSat-2. To support recent NASA Operation Ice Bridge activities, CReSIS radars were adapted for installation and operation on the NASA DC-8 for deployments primarily to Antarctica for measurements over glacial ice in West Antarctica and sea ice, and on the NASA P-3 for deployments to Greenland and Arctic sea ice. The major integration activities included the development of antenna subsystems specifically tailored for the DC-8 and P-3 aircraft. This included a low-profile radar depth sounder/imager antenna assembly for the DC-8 with a minimal impact on the aircraft range, one of the largest VHF antenna arrays for the P-3, and a set of internal antennas structures and radomes for the P-3 bomb bay. The design and development of the antenna assemblies were focused on meeting a combination of instrument and mission requirements. We will present a description of each radar system including the antenna assemblies, instrument block diagrams, modes of operation, installation specifics for each OIB deployment, example results, and availability of data to external investigators.

  3. The Antarctic sea ice concentration budget of an ocean-sea ice coupled model

    NASA Astrophysics Data System (ADS)

    Lecomte, Olivier; Goosse, Hugues; Fichefet, Thierry; Holland, Paul R.; Uotila, Petteri

    2015-04-01

    The Antarctic sea ice concentration budget of the NEMO-LIM ocean-sea ice coupled model is computed and analyzed. Following a previously developed method, the sea ice concentration balance over the autumn-winter seasons is decomposed into four terms, including the sea ice concentration change during the period of interest, advection, divergence and a residual accounting for the net contribution of thermodynamics and ice deformation. Preliminary results from this analysis show that the geographical patterns of all budget terms over 1992-2010 are in qualitative agreement with the observed ones. Sea ice thermodynamic growth is maintained by horizontal divergence near the continent and in the central ice pack, while melting close to the ice edge is led by sea ice advection. Quantitatively however, the inner ice pack divergence and associated sea ice freezing are much stronger, as compared to observations. The advection of sea ice in both the central pack and the marginal areas are likewise stronger, which corroborates the findings of a previous study in which the same methods were applied to a fully coupled climate model. Nonetheless, the seasonal evolution of sea ice area and total extent are reasonably well simulated, since enhanced sea ice freezing due to larger divergence in the central pack is compensated by intensified melting in the outer pack owing to faster advection. Those strong dynamic components in the sea ice concentration budget are due to ice velocities that tend to be biased high all around Antarctica and particularly near the ice edge. The obtained results show that the applied method is particularly well suited for assessing the skills of an ocean-sea ice coupled model in simulating the seasonal and regional evolution of Antarctic sea ice for the proper physical reasons.

  4. Variability and trends in sea ice extent and ice production in the Ross Sea

    NASA Astrophysics Data System (ADS)

    Comiso, Josefino C.; Kwok, Ronald; Martin, Seelye; Gordon, Arnold L.

    2011-04-01

    Salt release during sea ice formation in the Ross Sea coastal regions is regarded as a primary forcing for the regional generation of Antarctic Bottom Water. Passive microwave data from November 1978 through 2008 are used to examine the detailed seasonal and interannual characteristics of the sea ice cover of the Ross Sea and the adjacent Bellingshausen and Amundsen seas. For this period the sea ice extent in the Ross Sea shows the greatest increase of all the Antarctic seas. Variability in the ice cover in these regions is linked to changes in the Southern Annular Mode and secondarily to the Antarctic Circumpolar Wave. Over the Ross Sea shelf, analysis of sea ice drift data from 1992 to 2008 yields a positive rate of increase in the net ice export of about 30,000 km2 yr-1. For a characteristic ice thickness of 0.6 m, this yields a volume transport of about 20 km3 yr-1, which is almost identical, within error bars, to our estimate of the trend in ice production. The increase in brine rejection in the Ross Shelf Polynya associated with the estimated increase with the ice production, however, is not consistent with the reported Ross Sea salinity decrease. The locally generated sea ice enhancement of Ross Sea salinity may be offset by an increase of relatively low salinity of the water advected into the region from the Amundsen Sea, a consequence of increased precipitation and regional glacial ice melt.

  5. Sea-ice thermodynamics and brine drainage.

    PubMed

    Worster, M Grae; Rees Jones, David W

    2015-07-13

    Significant changes in the state of the Arctic ice cover are occurring. As the summertime extent of sea ice diminishes, the Arctic is increasingly characterized by first-year rather than multi-year ice. It is during the early stages of ice growth that most brine is injected into the oceans, contributing to the buoyancy flux that mediates the thermo-haline circulation. Current operational sea-ice components of climate models often treat brine rejection between sea ice and the ocean similarly to a thermodynamic segregation process, assigning a fixed salinity to the sea ice, typical of multi-year ice. However, brine rejection is a dynamical, buoyancy-driven process and the salinity of sea ice varies significantly during the first growth season. As a result, current operational models may over predict the early brine fluxes from newly formed sea ice, which may have consequences for coupled simulations of the polar oceans. Improvements both in computational power and our understanding of the processes involved have led to the emergence of a new class of sea-ice models that treat brine rejection dynamically and should enhance predictions of the buoyancy forcing of the oceans. PMID:26032321

  6. Object-Based Aerial Photos Analysis for Arctic Sea Ice Melt Ponds and Pressure Ridges

    NASA Astrophysics Data System (ADS)

    Miao, X.; Xie, H.; Ke, C.; Lei, R.

    2014-12-01

    High resolution aerial photographs can provide detailed distribution of sea ice features so as to extract physical parameters to refine, validate, and improve climate models. For example, melt ponds play an important role in Earth's radiation balance since they strongly absorb solar radiation rather than reflecting it as snow and ice do. Furthermore, no previous studies have ever considered shadow in sea ice detection, which is ubiquitous in the aerial photographs especially in multi-year ice regions and during late melting phase. Based on our previous study, an object-based classification scheme is used to extract sea ice features including melt ponds and shadow from 163 selected aerial photographs taken during the Chinese National Arctic Research Expedition (CHINARE 2010). The classification algorithm includes three major steps as follows. (1) Image segmentation groups the neighboring pixels into objects according to the similarity of spectral and texture information; (2) random forest ensemble classifier can distinguish the following objects: water, general submerged ice, shadow, and ice/snow; and (3) polygon neighbor analysis can further separate melt ponds from general submerged ice according to the spatial neighboring relationship. Finally, the shadows are used to estimate the sea ice ridge distribution based on local solar illumination geometry. Our results illustrate the spatial distribution and morphological characters of melt ponds and ridges in different latitudes of the Arctic Pacific sector. This method can be applied to massive photos and images taken in past years and future years, in deriving the detailed sea ice feature distribution and changes through years.

  7. The seasonal evolution of sea ice floe size distribution

    NASA Astrophysics Data System (ADS)

    Perovich, Donald K.; Jones, Kathleen F.

    2014-12-01

    The Arctic sea ice cover undergoes large changes over an annual cycle. In winter and spring, the ice cover consists of large, snow-covered plate-like ice floes, with very little open water. By the end of summer, the snow cover is gone and the large floes have broken into a complex mosaic of smaller, rounded floes surrounded by a lace of open water. This evolution strongly affects the distribution and fate of the solar radiation deposited in the ice-ocean system and consequently the heat budget of the ice cover. In particular, increased floe perimeter can result in enhanced lateral melting. We attempt to quantify the floe evolution process through the concept of a floe size distribution that is modified by lateral melting and floe breaking. A time series of aerial photographic surveys made during the SHEBA field experiment is analyzed to determine evolution of the floe size distribution from spring through summer. Based on earlier studies, we assume the floe size cumulative distribution could be represented by a power law D-?, where D is the floe diameter. The exponent ? as well as the number density of floes Ntot are estimated from measurements of total ice area and perimeter. As summer progressed, there was an increase in ? as the size distribution shifted toward smaller floes and the number of floes increased. Lateral melting causes the distribution to deviate from a power law for small floe sizes.

  8. MODIS Data and Services at the National Snow and Ice Data Center (NSIDC)

    NASA Astrophysics Data System (ADS)

    McAllister, M.; Fowler, D. K.

    2010-12-01

    For nearly a decade, the National Snow and Ice Data Center (NSIDC) has archived and distributed snow and sea ice products derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the NASA Earth Observing System (EOS) Aqua and Terra satellites. The archive contains a wide selection of data products relevant to cryospheric science, including snow and sea ice. NSIDC offers a variety of methods for obtaining these data. Our Data Pool is an online archive which allows a user to very quickly download desired products and also has a spatial and temporal search capability. The Warehouse Inventory Search Tool (WIST) contains a complete set of metadata for all products which can be searched for and ordered. WIST also allows a user to order spatial, temporal, and parameter subsets of the data. Users can also request that they be added to our subscription list which makes it possible to have new MODIS data automatically ftp’d or staged on a local server as it is archived at NSIDC. Since MODIS products are in HDF-EOS format, NSIDC has developed a number of tools to assist with browsing, editing, reprojection, resampling, and format conversion including MODIS Swath-to-Grid Toolbox (MS2GT) and the MODIS Interactive Subsetting Tool (MIST). MS2GT was created to produce a seamless output grid from multiple input files corresponding to successively acquired, 5-minute MODIS scenes. NSIDC created the MIST to also provide subsets of certain Version 5 MODIS products, over the Greenland Climate Network (GC-Net) and the International Arctic Systems for Observing the Atmosphere (IASOA) stations.

  9. The History of Snow and Ice on the Summits of Hawai`i

    E-print Network

    Schörghofer, Norbert

    The History of Snow and Ice on the Summits of Hawai`i Norbert*on of past climate · No instrumental records · Historical Accounts (Texts, Paintings?) ­ snow cover years that Mr. Young has been on the island, he has never seen Mouna Kaah free from snow" ­ 1825

  10. Comparing springtime ice-algal chlorophyll a and physical properties of multi-year and first-year sea ice from the Lincoln Sea.

    PubMed

    Lange, Benjamin A; Michel, Christine; Beckers, Justin F; Casey, J Alec; Flores, Hauke; Hatam, Ido; Meisterhans, Guillaume; Niemi, Andrea; Haas, Christian

    2015-01-01

    With near-complete replacement of Arctic multi-year ice (MYI) by first-year ice (FYI) predicted to occur within this century, it remains uncertain how the loss of MYI will impact the abundance and distribution of sea ice associated algae. In this study we compare the chlorophyll a (chl a) concentrations and physical properties of MYI and FYI from the Lincoln Sea during 3 spring seasons (2010-2012). Cores were analysed for texture, salinity, and chl a. We identified annual growth layers for 7 of 11 MYI cores and found no significant differences in chl a concentration between the bottom first-year-ice portions of MYI, upper old-ice portions of MYI, and FYI cores. Overall, the maximum chl a concentrations were observed at the bottom of young FYI. However, there were no significant differences in chl a concentrations between MYI and FYI. This suggests little or no change in algal biomass with a shift from MYI to FYI and that the spatial extent and regional variability of refrozen leads and younger FYI will likely be key factors governing future changes in Arctic sea ice algal biomass. Bottom-integrated chl a concentrations showed negative logistic relationships with snow depth and bulk (snow plus ice) integrated extinction coefficients; indicating a strong influence of snow cover in controlling bottom ice algal biomass. The maximum bottom MYI chl a concentration was observed in a hummock, representing the thickest ice with lowest snow depth of this study. Hence, in this and other studies MYI chl a biomass may be under-estimated due to an under-representation of thick MYI (e.g., hummocks), which typically have a relatively thin snowpack allowing for increased light transmission. Therefore, we suggest the on-going loss of MYI in the Arctic Ocean may have a larger impact on ice-associated production than generally assumed. PMID:25901605

  11. Comparing Springtime Ice-Algal Chlorophyll a and Physical Properties of Multi-Year and First-Year Sea Ice from the Lincoln Sea

    PubMed Central

    Lange, Benjamin A.; Michel, Christine; Beckers, Justin F.; Casey, J. Alec; Flores, Hauke; Hatam, Ido; Meisterhans, Guillaume; Niemi, Andrea; Haas, Christian

    2015-01-01

    With near-complete replacement of Arctic multi-year ice (MYI) by first-year ice (FYI) predicted to occur within this century, it remains uncertain how the loss of MYI will impact the abundance and distribution of sea ice associated algae. In this study we compare the chlorophyll a (chl a) concentrations and physical properties of MYI and FYI from the Lincoln Sea during 3 spring seasons (2010-2012). Cores were analysed for texture, salinity, and chl a. We identified annual growth layers for 7 of 11 MYI cores and found no significant differences in chl a concentration between the bottom first-year-ice portions of MYI, upper old-ice portions of MYI, and FYI cores. Overall, the maximum chl a concentrations were observed at the bottom of young FYI. However, there were no significant differences in chl a concentrations between MYI and FYI. This suggests little or no change in algal biomass with a shift from MYI to FYI and that the spatial extent and regional variability of refrozen leads and younger FYI will likely be key factors governing future changes in Arctic sea ice algal biomass. Bottom-integrated chl a concentrations showed negative logistic relationships with snow depth and bulk (snow plus ice) integrated extinction coefficients; indicating a strong influence of snow cover in controlling bottom ice algal biomass. The maximum bottom MYI chl a concentration was observed in a hummock, representing the thickest ice with lowest snow depth of this study. Hence, in this and other studies MYI chl a biomass may be under-estimated due to an under-representation of thick MYI (e.g., hummocks), which typically have a relatively thin snowpack allowing for increased light transmission. Therefore, we suggest the on-going loss of MYI in the Arctic Ocean may have a larger impact on ice–associated production than generally assumed. PMID:25901605

  12. Unlocking a Sea Ice Secret

    SciTech Connect

    Dr. Rachel Obbard

    2013-04-22

    Dr. Rachel Obbard and her research group from Dartmouth College traveled to the Antarctic to collect samples of sea ice. Next stop: the GeoSoilEnviroCARS x-ray beamline at the Advanced Photon Source at Argonne National Laboratory in Illinois. This U.S. Department of Energy Office of Science synchrotron x-ray research facility gave the Obbard team the frontier scientific tools they needed to study the path bromide takes as it travels from the ocean to the atmosphere.

  13. Satellite Observations of Blowing Snow in and Around Antarctica: Implications for Ice Sheet Mass Balance and Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    Palm, S. P.; Yang, Y.; Marshak, A.

    2014-12-01

    Blowing snow in the polar regions is known to be important for a variety of reasons including ice sheet mass balance, atmospheric water vapor transport, interpretation of paleoclimate records and atmospheric chemistry. Over Antarctica, persistent katabatic winds produce extreme blowing snow events often covering 100,000 square kilometers or more and reaching heights of 300-400 meters. New techniques of blowing snow detection using active and passive satellite data are providing a new understanding of the frequency, magnitude and spatial coverage of blowing snow over and around the Antarctic continent. Current research is utilizing these methods to obtain a nearly 10 year climatology of blowing snow events over Antarctica and estimate the amount of mass being blown off the continent and sublimated into the atmosphere on an annual basis. In addition, recent research indicates that blowing snow over sea ice may be important in the process of transporting seal salt aerosol into the atmosphere where it is implicated in the production of bromine compounds that strongly influence many aspects of tropospheric chemistry.

  14. Measurements of thermal infrared spectral reflectance of frost, snow, and ice

    NASA Technical Reports Server (NTRS)

    Salisbury, John W.; D'Aria, Dana M.; Wald, Andrew

    1994-01-01

    Because much of Earth's surface is covered by frost, snow, and ice, the spectral emissivities of these materials are a significant input to radiation balance calculations in global atmospheric circulation and climate change models. Until now, however, spectral emissivities of frost and snow have been calculated from the optical constants of ice. We have measured directional hemispherical reflectance spectra of frost, snow, and ice from which emissivities can be predicted using Kirchhoff's law (e = 1-R). These measured spectra show that contrary to conclusions about the emissivity of snow drawn from previously calculated spectra, snow emissivity departs significantly from blackbody behavior in the 8-14 micrometer region of the spectrum; snow emissivity decreases with both increasing particle size and increasing density due to packing or grain welding; while snow emissivity increases due to the presence of meltwater.

  15. ICESat Observations of Seasonal and Interannual Variations of Sea-Ice Freeboard and Estimated Thickness in the Weddell Sea, Antarctica (2003-2009)

    NASA Technical Reports Server (NTRS)

    Yi, Donghui; Robbins, John W.

    2010-01-01

    Sea-ice 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 ice, to estimate sea-ice thickness. Sea-ice freeboard and thickness distributions show clear seasonal variations that reflect the yearly cycle of growth and decay of the Weddell Sea (Antarctica) pack ice. During October-November, sea ice grows to its seasonal 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 ice melts away and the sea-ice 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-ice 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.

  16. Snow and Ice Mask for the MODIS Aerosol Products

    NASA Technical Reports Server (NTRS)

    Li, Rong-Rong; Remer, Lorraine; Kaufman, Yoram J.; Mattoo, Shana; Gao, Bo-Cai; Vermote, Eric

    2005-01-01

    The atmospheric products have been derived operationally from multichannel imaging data collected with the Moderate Resolution Imaging SpectroRadiometers (MODIS) on board the NASA Terra and Aqua spacecrafts. Preliminary validations of the products were previously reported. Through analysis of more extensive time-series of MODIS aerosol products (Collection 4), we have found that the aerosol products over land areas are slightly contaminated by snow and ice during the springtime snow-melting season. We have developed an empirical technique using MODIS near-IR channels centered near 0.86 and 1.24 pm and a thermal emission channel near 11 pm to mask out these snow-contaminated pixels over land. Improved aerosol retrievals over land have been obtained. Sample results from application of the technique to MODIS data acquired over North America, northern Europe, and northeastern Asia are presented. The technique has been implemented into the MODIS Collection 5 operational algorithm for retrieving aerosols over land from MODIS data.

  17. Modeled Trends in Antarctic Sea Ice Thickness

    NASA Technical Reports Server (NTRS)

    Holland, Paul R.; Bruneau, Nicolas; Enright, Clare; Losch, Martin; Kurtz, Nathan T.; Kwok, Ron

    2014-01-01

    Unlike the rapid sea ice losses reported in the Arctic, satellite observations show an overall increase in Antarctic sea ice concentration over recent decades. However, observations of decadal trends in Antarctic ice thickness, and hence ice volume, do not currently exist. In this study a model of the Southern Ocean and its sea ice, forced by atmospheric reanalyzes, is used to assess 1992-2010 trends in ice thickness and volume. The model successfully reproduces observations of mean ice concentration, thickness, and drift, and decadal trends in ice concentration and drift, imparting some confidence in the hindcasted trends in ice thickness. The model suggests that overall Antarctic sea ice volume has increased by approximately 30 cu km/yr (0.4%/ yr) as an equal result of areal expansion (20 x 10(exp 3) sq km/yr or 0.2%/yr) and thickening (1.5 mm/yr or 0.2%/yr). This ice volume increase is an order of magnitude smaller than the Arctic decrease, and about half the size of the increased freshwater supply from the Antarctic Ice Sheet. Similarly to the observed ice concentration trends, the small overall increase in modeled ice volume is actually the residual of much larger opposing regional trends. Thickness changes near the ice edge follow observed concentration changes, with increasing concentration corresponding to increased thickness. Ice thickness increases are also found in the inner pack in the Amundsen and Weddell Seas, where the model suggests that observed ice-drift trends directed toward the coast have caused dynamical thickening in autumn and winter. Modeled changes are predominantly dynamic in origin in the Pacific sector and thermodynamic elsewhere.

  18. Singlet molecular oxygen on natural snow and ice

    NASA Astrophysics Data System (ADS)

    Bower, J. P.; Anastasio, C.

    2010-12-01

    Singlet molecular oxygen (1O2*) is a reactive intermediate formed when a chromophore absorbs light and subsequently transfers energy to dissolved oxygen. As an oxidant, 1O2* reacts rapidly with a number of electron-rich environmental pollutants. In our work, we show enhanced kinetics for 1O2* in frozen solutions, where its rate of formation (Rf) and steady state concentration ([1O2*]) can be many orders of magnitude higher than found in the same unfrozen solution. Our goal here is to identify the contribution of 1O2* to the decay of pollutants on snow and ice. We conducted experiments in laboratory solutions made to simulate the concentrations and characteristics of natural snow, as well as in natural snow collected in the Sierra Nevada mountains of California and at Summit, Greenland. Natural snow contains a mixture of inorganic salts and organic species that can function as sources and/or sinks for oxidants, as well as contribute colligative control on the volume of quasi-liquid layers that occur at the surface and grain boundaries of ice. In our experiments, solutions typically contained up to five components: (1) Furfuryl alcohol (FFA), a commonly used probe for 1O2*, (2) Rose Bengal (RB), a 1O2* sensitizer, (3) HOOH, a photochemical precursor for hydroxyl radical (?OH), (4) glycerol to simulate unknown, naturally occurring sinks for ?OH, and (5) sodium sulfate to control the total concentration of solutes. We illuminated samples in a temperature-controlled solar simulator and subsequently measured the loss of FFA using high performance liquid chromatography. To differentiate reactions of 1O2* from other sinks (e.g. ?OH), selective sink species were added to determine the fraction of FFA loss due to direct photolysis, reaction with 1O2*, and reaction with ?OH. We verified reactions of 1O2* with FFA by two methods. First, we utilized the kinetic solvent isotope effect, where an enhancement of FFA loss in a mixture of D2O/water is indicative 1O2* since [1O2*] is higher in D2O than it is in pure water. Secondly, we conducted tests looking at pyranone formed from the reaction of FFA + 1O2*. A combination of these methods will allow us to determine 1O2* kinetics in natural snow, where its sources and sinks are unknown. This research will help determine the importance of 1O2* to the decay of pollutants in cold regions.

  19. Recent Advances in Satellite and Airborne Altimetry over Arctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Farrell, S. L.; Newman, T.; Richter-Menge, J.; Haas, C.; Petty, A.; McAdoo, D. C.; Connor, L. N.

    2014-12-01

    Over the last two decades altimeters on satellite and aircraft platforms have revolutionized our understanding of Arctic sea ice mass balance. Satellite laser and radar altimeters provide unique measurements of sea ice elevation, from which ice thickness may be derived, across basin scales and interdecadal time periods. Meanwhile airborne altimetry, together with high-resolution digital imagery, provides a range of novel observations that describe key features of the ice pack including its snow cover, surface morphology and deformation characteristics. We provide an update on current Arctic sea ice thickness conditions based on IceBridge measurements, discussing these in the context of previously observed decadal change. Fundamental to the goal of understanding interannual variability, and monitoring long-term trends in sea ice volume, is the accurate characterization of measurement uncertainty. This is particularly true when linking observations from different sensors. We discuss recent advances in tracking and quantifying the major components of the altimetric sea ice thickness error budget. We pay particular attention to two major components of the error: freeboard and snow loading uncertainty. We describe novel measurement techniques that are helping to reduce measurement uncertainty and allowing, for the first time, quantification of errors with respect to ice type.

  20. Modeling the heating and melting of sea ice through light absorption by microalgae

    NASA Astrophysics Data System (ADS)

    Zeebe, Richard E.; Eicken, Hajo; Robinson, Dale H.; Wolf-Gladrow, Dieter; Dieckmann, Gerhard S.

    1996-01-01

    In sea ice of polar regions, high concentrations of microalgae are observed during the spring. Algal standing stocks may attain peak values of over 300 mg chl a m-2 in the congelation ice habitat. As of yet, the effect of additional heating of sea ice through conversion of solar radiation into heat by algae has not been investigated in detail. Local effects, such as a decrease in albedo, increasing melt rates, and a decrease of the physical strength of ice sheets may occur. To investigate the effects of microalgae on the thermal regime of sea ice, a time-dependent, one-dimensional thermodynamic model of sea ice was coupled to a bio-optical model. A spectral one-stream model was employed to determine spectral attenuation by snow, sea ice, and microalgae. Beer's law was assumed to hold for every wavelength. Energy absorption was obtained by calculating the divergence of irradiance in every layer of the model (?z = 1 cm). Changes in sea ice temperature profiles were calculated by solving the heat conduction equation with a finite difference scheme. Model results indicate that when algal biomass is concentrated at the bottom of congelation ice, melting of ice resulting from the additional conversion of solar radiation into heat may effectively destroy the algal habitat, thereby releasing algal biomass into the water column. An algal layer located in the top of the ice sheet induced a significant increase in sea ice temperature (?T > 0.3 K) for snow depths less than 5 cm and algal standing stocks higher than 150 mg chl a m-2. Furthermore, under these conditions, brine volume increased by 21% from 181 to 219 parts per thousand, which decreased the physical strength of the ice.

  1. What Can Sea Ice Reconstructions Tell Us About Recent Regional Trends in Sea Ice Around Antarctica?

    NASA Astrophysics Data System (ADS)

    Abram, N.; Mulvaney, R.; Murphy, E. J.

    2014-12-01

    Satellite observations of recent sea ice changes around Antarctica reveal regionally heterogeneous trends, but with an overall increasing trend in Antarctic-wide sea ice extent. Proposed mechanisms to account for increasing sea ice extent around Antarctica include freshening of the ocean surface due to melting of land ice and northward wind drift associated with strengthening of the Southern Ocean westerly winds. In this study we use extended, regional reconstructions of Antarctic sea ice changes from ice core chemistry and reanalysis of the South Orkney fast ice series to examine long-term relationships between Antarctic regional sea ice changes and surface winds. The formation and breakout of fast ice at the South Orkney islands (Murphy et al., 2014) indicates that westerly wind strength is an important factor in determining spring sea ice retreat in the Weddell Sea region. In contrast, autumn sea ice formation is more strongly influenced by long-lived ocean temperature anomalies and sea ice migration from the previous year, highlighting the multiple influences that act at different times of the year to determine the overall extent of winter sea ice. To assess the hypothesized role of westerly wind changes in driving opposing patterns of recent sea ice change between the Ross Sea and Bellingshausen Sea, we also present a comparison of ice core MSA evidence for sea ice changes derived from the James Ross Island (Mulvaney et al., 2012) and Erebus Saddle (Rhodes et al., 2012) ice cores, and view this in the context of trends in the Southern Annular Mode (Abram et al., 2014) over the last 200 years. References: Abram et al., 2014. Evolution of the Southern Annular Mode over the past millennium. Nature Climate Change. doi: 10.1038/nclimate2235 Mulvaney et al., 2012. Recent Antarctic Peninsula warming relative to Holocene temperature and ice-shelf history. Nature. doi: 10.1038/nature11391 Murphy et al., 2014. Variability of sea ice in the northern Weddell Sea during the 20th century. Journal of Geophysical Research. doi: 10.1002/2013JC009511 Rhodes et al., 2012. Little Ice Age climate and oceanic conditions of the Ross Sea, Antarctica, from a coastal ice core record. Climate of the Past. doi: 10.5194/cp-8-1223-2012

  2. A toy model of sea ice growth

    NASA Technical Reports Server (NTRS)

    Thorndike, Alan S.

    1992-01-01

    My purpose here is to present a simplified treatment of the growth of sea ice. By ignoring many details, it is possible to obtain several results that help to clarify the ways in which the sea ice cover will respond to climate change. Three models are discussed. The first deals with the growth of sea ice during the cold season. The second describes the cycle of growth and melting for perennial ice. The third model extends the second to account for the possibility that the ice melts away entirely in the summer. In each case, the objective is to understand what physical processes are most important, what ice properties determine the ice behavior, and to which climate variables the system is most sensitive.

  3. Spatial and temporal variability of snow accumulation using ground-penetrating radar and ice cores on a Svalbard glacier

    E-print Network

    Moore, John

    Spatial and temporal variability of snow accumulation using ground-penetrating radar and ice cores.The profile passed two shallow and one deep ice-core sites.Two internal radar reflection layers were dated layering in snow or ice. Layering in radar images of glacier snow or firn can be attributed to differences

  4. Sea Ice Biogeochemistry: A Guide for Modellers

    PubMed Central

    Tedesco, Letizia; Vichi, Marcello

    2014-01-01

    Sea ice is a fundamental component of the climate system and plays a key role in polar trophic food webs. Nonetheless sea ice biogeochemical dynamics at large temporal and spatial scales are still rarely described. Numerical models may potentially contribute integrating among sparse observations, but available models of sea ice biogeochemistry are still scarce, whether their relevance for properly describing the current and future state of the polar oceans has been recently addressed. A general methodology to develop a sea ice biogeochemical model is presented, deriving it from an existing validated model application by extension of generic pelagic biogeochemistry model parameterizations. The described methodology is flexible and considers different levels of ecosystem complexity and vertical representation, while adopting a strategy of coupling that ensures mass conservation. We show how to apply this methodology step by step by building an intermediate complexity model from a published realistic application and applying it to analyze theoretically a typical season of first-year sea ice in the Arctic, the one currently needing the most urgent understanding. The aim is to (1) introduce sea ice biogeochemistry and address its relevance to ocean modelers of polar regions, supporting them in adding a new sea ice component to their modelling framework for a more adequate representation of the sea ice-covered ocean ecosystem as a whole, and (2) extend our knowledge on the relevant controlling factors of sea ice algal production, showing that beyond the light and nutrient availability, the duration of the sea ice season may play a key-role shaping the algal production during the on going and upcoming projected changes. PMID:24586604

  5. Physical control of chlorophyll a, POC, and TPN distributions in the pack ice of the Ross Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Arrigo, Kevin R.; Robinson, Dale H.; Dunbar, Robert B.; Leventer, Amy R.; Lizotte, Michael P.

    2003-10-01

    The pack ice ecosystem of the Ross Sea was investigated along a 1470-km north-south transect during the spring 1998 oceanographic program Research on Ocean-Atmosphere Variability and Ecosystem Response in the Ross Sea (ROAVERRS). Snow and sea ice thickness along the transect varied latitudinally, with thinner snow and ice at the northern ice edge and thin new ice in the vicinity of the Ross Sea polynya. Relative to springtime observations in other sea ice regions, algal chlorophyll a (Chl a) concentrations were low. In contrast, particulate organic carbon (POC), total particulate nitrogen (TPN), and POC:Chl a were all high, indicating either that the ice contained substantial amounts of detritus or nonphotosynthetic organisms, or that the algae had a high POC:Chl a ratio. The abundance of Chl a, POC, and TPN in the sea ice was related to ice age and thickness, as well as to snow depth: older ice had thinner snow cover and contained higher algal biomass while new ice in the polynya had lower biomass. Older pack ice was dominated by diatoms (particularly Fragilariopsis cylindrus) and had vertical distributions of Chl a, POC, and TPN that were related to salinity, with higher biomass at the ice-water interface. Fluorescence-based measurements of photosynthetic competence (Fv/Fm) were higher at ice-water interfaces, and photosynthesis-irradiance characteristics measured for bottom ice algae were comparable to those measured in pack ice communities of other regions. Nutrient concentrations in extracted sea ice brines showed depletion of silicate and nitrate, depletion or regeneration of phosphate and nitrite, and production of ammonium when normalized to seawater salinity; however, concentrations of dissolved inorganic nitrogen, phosphorous, and silica were typically above levels likely to limit algal growth. In areas where pack ice and snow cover were thickest, light levels could be limiting to algal photosynthesis. Enrichment of ?13C-POC in the sea ice was correlated with the accumulation of POC, suggesting that carbon sources for photosynthesis might shift in response to decreasing CO2 supply. Comparisons between new ice and underlying waters showed similar algal species dominance (Phaeocystis antarctica) implying incorporation of phytoplankton, with substantially higher POC and TPN concentrations in the ice.

  6. Melt ponds on Arctic sea ice determined from MODIS satellite data using an artificial neural network

    NASA Astrophysics Data System (ADS)

    Rösel, A.; Kaleschke, L.; Birnbaum, G.

    2012-04-01

    Melt ponds on sea ice strongly reduce the surface albedo and accelerate the decay of Arctic sea ice. Due to different spectral properties of snow, ice, and water, the fractional coverage of these distinct surface types can be derived from multispectral sensors like the Moderate Resolution Image Spectroradiometer (MODIS) using a spectral unmixing algorithm. The unmixing was implemented using a multilayer perceptron to reduce computational costs. Arctic-wide melt pond fractions and sea ice concentrations are derived from the level 3 MODIS surface reflectance product. The validation of the MODIS melt pond data set was conducted with aerial photos from the MELTEX campaign 2008 in the Beaufort Sea, data sets from the National Snow and Ice Data Center (NSIDC) for 2000 and 2001 from four sites spread over the entire Arctic, and with ship observations from the trans-Arctic HOTRAX cruise in 2005. The root-mean-square errors range from 3.8 % for the comparison with HOTRAX data, over 10.7 % for the comparison with NSIDC data, to 10.3 % and 11.4 % for the comparison with MELTEX data, with coefficient of determination ranging from R2=0.28 to R2=0.45. The mean annual cycle of the melt pond fraction per grid cell for the entire Arctic shows a strong increase in June, reaching a maximum of 15 % by the end of June. The zonal mean of melt pond fractions indicates a dependence of the temporal development of melt ponds on the geographical latitude, and has its maximum in mid-July at latitudes between 80° and 88° N. Furthermore, the MODIS results are used to estimate the influence of melt ponds on retrievals of sea ice concentrations from passive microwave data. Results from a case study comparing sea ice concentrations from ARTIST Sea Ice-, NASA Team 2-, and Bootstrap-algorithms with MODIS sea ice concentrations indicate an underestimation of around 40 % for sea ice concentrations retrieved with microwave algorithms.

  7. Investigation of radar discrimination of sea ice

    NASA Technical Reports Server (NTRS)

    Parashar, S. K.; Biggs, A. W.; Fung, A. K.; Moore, R. K.

    1974-01-01

    The ability of radar to discriminate sea ice types and their thickness was studied. Radar backscatter measurements at 400 MHz (multi-polarization) and 13.3 GHz (VV polarization) obtained from NASA Earth Resources Aircraft Program Mission 126 were analyzed in detail. The scatterometer data were separated into seven categories of sea ice according to age and thickness as interpreted from stereo aerial photographs. The variations of radar backscatter cross-section with sea ice thickness at various angles are presented at the two frequencies. There is a reversal of angular character of radar return from sea ice less than 18 cm thick at the two frequencies. Multi-year ice (sea ice greater than 180 cm thick) gives strongest return at 13.3 GHz. First-year ice (30 cm to 90 cm thick) gives strongest return at 400 MHz. Open water can be differentiated at both the frequencies. Four-polarization 16.5 GHz radar imagery was also obtained. Open water and three categories of sea ice can be identified on the images. The results of the imagery analysis are consistent with the radar scatterometer results.

  8. Satellite Remote Sensing: Passive-Microwave Measurements of Sea Ice

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    Satellite passive-microwave measurements of sea ice have provided global or near-global sea ice data for most of the period since the launch of the Nimbus 5 satellite in December 1972, and have done so with horizontal resolutions on the order of 25-50 km and a frequency of every few days. These data have been used to calculate sea ice concentrations (percent areal coverages), sea ice extents, the length of the sea ice season, sea ice temperatures, and sea ice velocities, and to determine the timing of the seasonal onset of melt as well as aspects of the ice-type composition of the sea ice cover. In each case, the calculations are based on the microwave emission characteristics of sea ice and the important contrasts between the microwave emissions of sea ice and those of the surrounding liquid-water medium.

  9. Evidence for radionuclide transport by sea ice

    USGS Publications Warehouse

    Meese, D.A.; Reimnitz, E.; Tucker, W. B., III; Gow, A.J.; Bischof, J.; Darby, D.

    1997-01-01

    Ice and ice-borne sediments were collected across the Arctic Basin during the Arctic Ocean Section, 1994 (AOS-94), a recent US/Canada trans- Arctic expedition. Sediments were analysed for 137Cs, clay mineralogy and carbon. Concentrations of 137Cs ranged from 5 to 73 Bq kg-1 in the ice- borne sediments. Concentrations of ice samples without sediment were all less than 1 Bq m-3. The sediment sample with the highest 137Cs concentration (73 Bq kg-1)was collected in the Beaufort Sea. This concentration was significantly higher than in bottom sediments collected in the same area, indicating an ice transport mechanism from an area with correspondingly higher concentrations. Recent results from the application of ice transport models and sediment analyses indicate that it is very likely that sediments are transported by ice, from the Siberian shelf areas to the Beaufort Sea.

  10. Arctic sea-ice ridges—Safe heavens for sea-ice fauna during periods of extreme ice melt?

    NASA Astrophysics Data System (ADS)

    Gradinger, Rolf; Bluhm, Bodil; Iken, Katrin

    2010-01-01

    The abundances and distribution of metazoan within-ice meiofauna (13 stations) and under-ice fauna (12 stations) were investigated in level sea ice and sea-ice ridges in the Chukchi/Beaufort Seas and Canada Basin in June/July 2005 using a combination of ice coring and SCUBA diving. Ice meiofauna abundance was estimated based on live counts in the bottom 30 cm of level sea ice based on triplicate ice core sampling at each location, and in individual ice chunks from ridges at four locations. Under-ice amphipods were counted in situ in replicate ( N=24-65 per station) 0.25 m 2 quadrats using SCUBA to a maximum water depth of 12 m. In level sea ice, the most abundant ice meiofauna groups were Turbellaria (46%), Nematoda (35%), and Harpacticoida (19%), with overall low abundances per station that ranged from 0.0 to 10.9 ind l -1 (median 0.8 ind l -1). In level ice, low ice algal pigment concentrations (<0.1-15.8 ?g Chl a l -1), low brine salinities (1.8-21.7) and flushing from the melting sea ice likely explain the low ice meiofauna concentrations. Higher abundances of Turbellaria, Nematoda and Harpacticoida also were observed in pressure ridges (0-200 ind l -1, median 40 ind l -1), although values were highly variable and only medians of Turbellaria were significantly higher in ridge ice than in level ice. Median abundances of under-ice amphipods at all ice types (level ice, various ice ridge structures) ranged from 8 to 114 ind m -2 per station and mainly consisted of Apherusa glacialis (87%), Onisimus spp. (7%) and Gammarus wilkitzkii (6%). Highest amphipod abundances were observed in pressure ridges at depths >3 m where abundances were up to 42-fold higher compared with level ice. We propose that the summer ice melt impacted meiofauna and under-ice amphipod abundance and distribution through (a) flushing, and (b) enhanced salinity stress at thinner level sea ice (less than 3 m thickness). We further suggest that pressure ridges, which extend into deeper, high-salinity water, become accumulation regions for ice meiofauna and under-ice amphipods in summer. Pressure ridges thus might be crucial for faunal survival during periods of enhanced summer ice melt. Previous estimates of Arctic sea ice meiofauna and under-ice amphipods on regional and pan-Arctic scales likely underestimate abundances at least in summer because they typically do not include pressure ridges.

  11. Object-based Image Classification of Arctic Sea Ice and Melt Ponds through Aerial Photos

    NASA Astrophysics Data System (ADS)

    Miao, X.; Xie, H.; Li, Z.; Lei, R.

    2013-12-01

    The last six years have marked the lowest Arctic summer sea ice extents in the modern era, with a new record summer minimum (3.4 million km2) set on 13 September 2012. It has been predicted that the Arctic could be free of summer ice within the next 25-30. The loss of Arctic summer ice could have serious consequences, such as higher water temperature due to the positive feedback of albedo, more powerful and frequent storms, rising sea levels, diminished habitats for polar animals, and more pollution due to fossil fuel exploitation and/ or increased traffic through the Northwest/ Northeast Passage. In these processes, melt ponds play an important role in Earth's radiation balance since they strongly absorb solar radiation rather than reflecting it as snow and ice do. Therefore, it is necessary to develop the ability of predicting the sea ice/ melt pond extents and space-time evolution, which is pivotal to prepare for the variation and uncertainty of the future environment, political, economic, and military needs. A lot of efforts have been put into Arctic sea ice modeling to simulate sea ice processes. However, these sea ice models were initiated and developed based on limited field surveys, aircraft or satellite image data. Therefore, it is necessary to collect high resolution sea ice aerial photo in a systematic way to tune up, validate, and improve models. Currently there are many sea ice aerial photos available, such as Chinese Arctic Exploration (CHINARE 2008, 2010, 2012), SHEBA 1998 and HOTRAX 2005. However, manually delineating of sea ice and melt pond from these images is time-consuming and labor-intensive. In this study, we use the object-based remote sensing classification scheme to extract sea ice and melt ponds efficiently from 1,727 aerial photos taken during the CHINARE 2010. The algorithm includes three major steps as follows. (1) Image segmentation groups the neighboring pixels into objects according to the similarity of spectral and texture information; (2) random forest ensemble classifier can distinguish the following objects: water, submerged ice, shadow, and ice/snow; and (3) polygon neighbor analysis can further separate melt ponds from submerged ice according to the spatial neighboring relationship. Our results illustrate the spatial distribution and morphological characters of melt ponds in different latitudes of the Arctic Pacific sector. This method can be applied to massive photos and images taken in past years and future years, in deriving the detailed sea ice and melt pond distribution and changes through years.

  12. Derive Icebridge Sea-Ice Freeboard and Thickness Data through Full Waveform Analysis

    NASA Astrophysics Data System (ADS)

    Yi, D.; Harbeck, J. P.; Manizade, S.; Hofton, M. A.; Kurtz, N. T.; Studinger, M.

    2014-12-01

    The current Operation IceBridge Airborne Topographic Mapper (ATM) sea-ice freeboard and thickness data product at the National Snow and Ice Data Center (NSIDC) requires coincident Digital Mapping System (DMS) imagery or Continuous Airborne Mapping By Optical Translator (CAMBOT) imagery to produce. However, some of the IceBridge ATM and Land, Vegetation, and Ice Sensor (LVIS) sea-ice flights have no coincident imagery data. In particular, the IceBridge "South Basin Transect" flights just north of the Canadian Archipelago have historically been flown under darkness (nighttime) and coincident imagery data are not available. Here we apply an algorithm using ATM waveform parameters to identify leads to derive sea-ice freeboard. ATM waveforms were fitted with Gaussian curves to calculate pulse width, peak location, pulse amplitude, and signal baseline. For each waveform, centroid, skewness, kurtosis, and pulse area were also calculated. Received waveform parameters, such as pulse width, pulse amplitude, pulse area, skewness, kurtosis, and transmitted/received pulse area ratio show a coherent response to variations of geophysical features along an ATM profile. These parameters, combined with elevation, were used to identify leads to enable sea-ice freeboard calculation. A similar algorithm is applied to the LVIS data to calculate sea-ice freeboard. Arctic sea-ice freeboards for ATM and LVIS data with no coincident visual imagery are derived in this study, extending the IceBridge sea-ice record over a large portion of thick multi-year sea ice. The results are evaluated/validated by using ATM data with coincident DMS imagery and near coincident ATM and LVIS data comparison.

  13. 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…

  14. Spatial Variability of Barrow-Area Shore-Fast Sea Ice and Its Relationships to Passive Microwave Emissivity

    NASA Technical Reports Server (NTRS)

    Maslanik, J. A.; Rivas, M. Belmonte; Holmgren, J.; Gasiewski, A. J.; Heinrichs, J. F.; Stroeve, J. C.; Klein, M.; Markus, T.; Perovich, D. K.; Sonntag, J. G.; Tape, K.

    2006-01-01

    Aircraft-acquired passive microwave data, laser radar height observations, RADARSAT synthetic aperture radar imagery, and in situ measurements obtained during the AMSR-Ice03 experiment are used to investigate relationships between microwave emission and ice characteristics over several space scales. The data fusion allows delineation of the shore-fast ice and pack ice in the Barrow area, AK, into several ice classes. Results show good agreement between observed and Polarimetric Scanning Radiometer (PSR)-derived snow depths over relatively smooth ice, with larger differences over ridged and rubbled ice. The PSR results are consistent with the effects on snow depth of the spatial distribution and nature of ice roughness, ridging, and other factors such as ice age. Apparent relationships exist between ice roughness and the degree of depolarization of emission at 10,19, and 37 GHz. This depolarization .would yield overestimates of total ice concentration using polarization-based algorithms, with indications of this seen when the NT-2 algorithm is applied to the PSR data. Other characteristics of the microwave data, such as effects of grounding of sea ice and large contrast between sea ice and adjacent land, are also apparent in the PSR data. Overall, the results further demonstrate the importance of macroscale ice roughness conditions such as ridging and rubbling on snow depth and microwave emissivity.

  15. Radiative and turbulent surface heat fluxes over sea ice in the western Weddell Sea in early summer

    NASA Astrophysics Data System (ADS)

    Vihma, Timo; Johansson, Milla M.; Launiainen, Jouko

    2009-04-01

    The radiative and turbulent heat fluxes between the snow-covered sea ice and the atmosphere were analyzed on the basis of observations during the Ice Station Polarstern (ISPOL) in the western Weddell Sea from 28 November 2004 to 2 January 2005. The net heat flux to the snowpack was 3 ± 2 W m-2 (mean ± standard deviation; defined positive toward snow), consisting of the net shortwave radiation (52 ± 8 W m-2), net longwave radiation (-29 ± 4 W m-2), latent heat flux (-14 ± 5 W m-2), and sensible heat flux (-6 ± 5 W m-2). The snowpack receives heat at daytime while releases heat every night. Snow thinning was due to approximately equal contributions of the increase of snow density, melt, and evaporation. The surface albedo only decreased from 0.9 to 0.8. During a case of cold air advection, the sensible heat flux was even below -50 W m-2. At night, the snow surface temperature was strongly controlled by the incoming longwave radiation. The diurnal cycle in the downward solar radiation drove diurnal cycles in 14 other variables. Comparisons against observations from the Arctic sea ice in summer indicated that at ISPOL the air was colder, surface albedo was higher, and a larger portion of the absorbed solar radiation was returned to the atmosphere via turbulent heat fluxes. The limited melt allowed larger diurnal cycles. Due to regional differences in atmospheric circulation and ice conditions, the ISPOL results cannot be fully generalized for the entire Antarctic sea ice zone.

  16. Arctic Sea Ice Maximum 2011 - Duration: 61 seconds.

    NASA Video Gallery

    AMSR-E Arctic Sea Ice: September 2010 to March 2011: Scientists tracking the annual maximum extent of Arctic sea ice said that 2011 was among the lowest ice extents measured since satellites began ...

  17. Radar backscattering from snow facies of the Greenland ice sheet: Results from the AIRSAR 1991 campaign

    NASA Technical Reports Server (NTRS)

    Rignot, Eric; Jezek, K.; Vanzyl, J. J.; Drinkwater, Mark R.; Lou, Y. L.

    1993-01-01

    In June 1991, the NASA/JPL airborne SAR (AIRSAR) acquired C- (lambda = 5.6cm), L- (lambda = 24cm), and P- (lambda = 68m) band polarimetric SAR data over the Greenland ice sheet. These data are processed using version 3.55 of the AIRSAR processor which provides radiometrically and polarimetrically calibrated images. The internal calibration of the AIRSAR data is cross-checked using the radar response from corner reflectors deployed prior to flight in one of the scenes. In addition, a quantitative assessment of the noise power level at various frequencies and polarizations is made in all the scenes. Synoptic SAR data corresponding to a swath width of about 12 by 50 km in length (compared to the standard 12 x 12 km size of high-resolution scenes) are also processed and calibrated to study transitions in radar backscatter as a function of snow facies at selected frequencies and polarizations. The snow facies on the Greenland ice sheet are traditionally categorized based on differences in melting regime during the summer months. The interior of Greenland corresponds to the dry snow zone where terrain elevation is the highest and no snow melt occurs. The lowest elevation boundary of the dry snow zone is known traditionally as the dry snow line. Beneath it is the percolation zone where melting occurs in the summer and water percolates through the snow freezing at depth to form massive ice lenses and ice pipes. At the downslope margin of this zone is the wet snow line. Below it, the wet snow zone corresponds to the lowest elevations where snow remains at the end of the summer. Ablation produces enough meltwater to create areas of snow saturated with water, together with ponds and lakes. The lowest altitude zone of ablation sees enough summer melt to remove all traces of seasonal snow accumulation, such that the surface comprises bare glacier ice.

  18. Exploring the utility of quantitative network design in evaluating Arctic sea ice thickness sampling strategies

    NASA Astrophysics Data System (ADS)

    Kaminski, T.; Kauker, F.; Eicken, H.; Karcher, M.

    2015-08-01

    We present a quantitative network design (QND) study of the Arctic sea ice-ocean system using a software tool that can evaluate hypothetical observational networks in a variational data assimilation system. For a demonstration, we evaluate two idealised flight transects derived from NASA's Operation IceBridge airborne ice surveys in terms of their potential to improve 10-day to 5-month sea ice forecasts. As target regions for the forecasts we select the Chukchi Sea, an area particularly relevant for maritime traffic and offshore resource exploration, as well as two areas related to the Barnett ice severity index (BSI), a standard measure of shipping conditions along the Alaskan coast that is routinely issued by ice services. Our analysis quantifies the benefits of sampling upstream of the target area and of reducing the sampling uncertainty. We demonstrate how observations of sea ice and snow thickness can constrain ice and snow variables in a target region and quantify the complementarity of combining two flight transects. We further quantify the benefit of improved atmospheric forecasts and a well-calibrated model.

  19. Arctic Sea Ice Thickness from Satellite Observations, Aircraft Field Campaign Measurements, and Numerical Model Simulations

    NASA Astrophysics Data System (ADS)

    Wang, X.; Kwok, R.; Zhang, J.; Liu, Y.; Key, J.

    2013-12-01

    Sea ice is an important indicator and effective modulator of regional and global climate change because it significantly affects the complex exchanges of momentum, heat, and mass between the sea and atmosphere. At present, there are datasets for Arctic sea ice thickness from satellite observations, aircraft field campaign measurements, numerical model simulations, and some in-situ measurements. Among satellite derived data sets, one satellite ice thickness product has been generated using NASA's Ice, Cloud and Land Elevation Satellite (ICESat) Geoscience Laser Altimeter System (GLAS) observations (Kwok et al., 2009), another has been produced from long-term optical (visible, near-IR, and thermal IR) imager data from NOAA Polar Orbiting Satellites (Wang et al., 2010). The approaches are completely different: the ICESat product estimates ice thickness from surface elevation; the optical imager approach estimates ice thickness by solving the surface energy budget equation. NASA's IceBridge program fills the gap between the loss of ICESat in 2010 and the launch of ICESat-2 in 2016. IceBridge employs an aircraft for altimeter and other measurements of the ice sheets and sea ice. The IceBridge Snow Radar, Digital Mapping System (DMS), Continuous Airborne Mapping By Optical Translator (CAMBOT), and Airborne Topographic Mapper (ATM) instruments can be used to estimate ice thickness with a methodology similar to that used for ICESat. Ice thickness has also been modeled with the numerical model called Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) (Zhang and Rothrock, 2003). Arctic sea ice thickness estimates from these different data sources will be examined and inter-compared to evaluate their consistency and validity with in-situ measurements. Arctic sea ice thickness variations over time and space will be also investigated.

  20. Tropical to mid-latitude snow and ice accumulation, flow and

    E-print Network

    Head III, James William

    ........................................................................................................................................................................................................................... Images from the Mars Express HRSC (High-Resolution Stereo Camera) of debris aprons at the base of massifsTropical to mid-latitude snow and ice accumulation, flow and glaciation on Mars J. W. Head1 , G of extremely ice-rich glacier-like viscous flow and sublimation. Together with new evidence for recent ice

  1. Influence of sea ice on Arctic precipitation.

    PubMed

    Kopec, Ben G; Feng, Xiahong; Michel, Fred A; Posmentier, Eric S

    2016-01-01

    Global climate is influenced by the Arctic hydrologic cycle, which is, in part, regulated by sea ice through its control on evaporation and precipitation. However, the quantitative link between precipitation and sea ice extent is poorly constrained. Here we present observational evidence for the response of precipitation to sea ice reduction and assess the sensitivity of the response. Changes in the proportion of moisture sourced from the Arctic with sea ice change in the Canadian Arctic and Greenland Sea regions over the past two decades are inferred from annually averaged deuterium excess (d-excess) measurements from six sites. Other influences on the Arctic hydrologic cycle, such as the strength of meridional transport, are assessed using the North Atlantic Oscillation index. We find that the independent, direct effect of sea ice on the increase of the percentage of Arctic sourced moisture (or Arctic moisture proportion, AMP) is 18.2 ± 4.6% and 10.8 ± 3.6%/100,000 km(2) sea ice lost for each region, respectively, corresponding to increases of 10.9 ± 2.8% and 2.7 ± 1.1%/1 °C of warming in the vapor source regions. The moisture source changes likely result in increases of precipitation and changes in energy balance, creating significant uncertainty for climate predictions. PMID:26699509

  2. Clues to Variability in Arctic Minimum Sea Ice Extent

    E-print Network

    Francis, Jennifer

    of the variation in winter ice extent in the Bering Sea, Barents Sea, and Sea of Okhotsk, but oceanographic forcing1 Clues to Variability in Arctic Minimum Sea Ice Extent Jennifer A. Francis1, Elias Hunter1: (732) 708-1217, Fax: (732) 872-1586, e-mail: francis@imcs.rutgers.edu #12;2 ABSTRACT Perennial sea ice

  3. 2011 Sea Ice Minimum - Duration: 61 seconds.

    NASA Video Gallery

    This video shows Arctic sea ice from March 7, 2011, to Sept. 9, 2011, ending with a comparison of the 30-year average minimum extent, shown in yellow, and the Northwest Passage, in red. (no audio) ...

  4. The impact of refreezing of melt ponds on Arctic sea ice thinning

    NASA Astrophysics Data System (ADS)

    Flocco, Daniela; Feltham, Daniel; Schroeder, David; Tsamados, Michel

    2015-04-01

    While the impact of melt ponds on the albedo-feedback mechanism of Arctic sea ice is well known, their impact in suppressing winter freeze up has been less studied. At the end of summer the melt ponds, covering a large fraction of the sea ice, start freezing and get trapped between the sea ice beneath and a thin surface layer of ice. The pond water stores latent heat that is released as they freeze. Ponds trapped under a layer of refrozen ice have been observed in the Arctic and our model results, confirmed by observations, show that the latent heat stored in the ice due to their presence slows the basal sea ice growth for over a month after a sea ice lid appears on their surface. We have developed a three layer, one-dimensional model of temperature and salinity evolution to study the refreezing process and conducted sensitivity studies to examine the factors affecting melt pond refreezing, including the presence of snow on a refreezing pond. We also show some preliminary results obtained by including this new process in the CICE model and in particular, the impact that the increased pond salinity and the refrozen pond persistence have on the sea ice basal growth.

  5. Seasonal sea ice predictions for the Arctic based on assimilation of remotely sensed observations

    NASA Astrophysics Data System (ADS)

    Kauker, F.; Kaminski, T.; Ricker, R.; Toudal-Pedersen, L.; Dybkjaer, G.; Melsheimer, C.; Eastwood, S.; Sumata, H.; Karcher, M.; Gerdes, R.

    2015-10-01

    The recent thinning and shrinking of the Arctic sea ice cover has increased the interest in seasonal sea ice forecasts. Typical tools for such forecasts are numerical models of the coupled ocean sea ice system such as the North Atlantic/Arctic Ocean Sea Ice 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 ice 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 ice thickness product in conjunction with the University of Bremen's snow depth product and the OSI SAF ice concentration and sea surface temperature products. We investigate the skill of predictions of the summer ice 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 ice thickness product that uses a spatially varying scaling factor.

  6. Melt ponds on Arctic sea ice determined from MODIS satellite data using an artificial neural network

    NASA Astrophysics Data System (ADS)

    Rösel, A.; Kaleschke, L.; Birnbaum, G.

    2011-10-01

    Melt ponds on sea ice strongly reduce the surface albedo and accelerate the decay of Arctic sea ice. Due to different spectral properties of snow, ice, and water, the fractional coverage of these distinct surface types can be derived from multispectral sensors like MODIS using a spectral unmixing algorithm. The unmixing was implemented using a multilayer perceptron (MLP) to reduce computational costs. Arctic-wide melt pond fractions and sea ice concentrations are derived from the level 3 MODIS surface reflectance product. The validation of the MODIS melt pond data set was conducted with aerial photos from the MELTEX campaign 2008 in the Beaufort Sea, data sets from the National Snow and Ice Data Center (NSIDC) for 2000 and 2001 from four sites spread over the entire Arctic, and with ship observations from the trans-Arctic HOTRAX cruise in 2005. The root-mean-square errors (RMSE) range from 3.8 % for the comparison with HOTRAX data, over 10.7 % for the comparison with NSIDC data, to 10.3 % and 11.4 % for the comparison with MELTEX data, with correlations coefficients ranging from R2 = 0.28 to R2 = 0.45. The mean annual cycle of the melt pond fraction for the entire Arctic shows a strong increase in June, reaching a maximum of 15 % by the end of June. The zonal mean of melt pond fractions indicates a dependence of the temporal development of melt ponds from the geographical latitude, and has its maximum in mid-July in latitudes between 80° and 88° N. Furthermore, the MODIS results are used to estimate the influence of melt ponds on retrievals of sea ice concentrations from passive microwave data. Results from a case study comparing sea ice concentrations from ASI-, NASA Team 2-, and Bootstrap-algorithms with MODIS sea ice concentrations indicate an underestimation of around 40 % for sea ice concentrations retrieved with microwave algorithms.

  7. The contribution of mycosporine-like amino acids, chromophoric dissolved organic matter and particles to the UV protection of sea-ice organisms in the Baltic Sea.

    PubMed

    Piiparinen, Jonna; Enberg, Sara; Rintala, Janne-Markus; Sommaruga, Ruben; Majaneva, Markus; Autio, Riitta; Vähätalo, Anssi V

    2015-05-01

    The effects of ultraviolet radiation (UVR) on the synthesis of mycosporine-like amino acids (MAAs) in sea-ice communities and on the other UV-absorption properties of sea ice were studied in a three-week long in situ experiment in the Gulf of Finland, Baltic Sea in March 2011. The untreated snow-covered ice and two snow-free ice treatments, one exposed to wavelengths > 400 nm (PAR) and the other to full solar spectrum (PAR + UVR), were analysed for MAAs and absorption coefficients of dissolved (aCDOM) and particulate (ap) fractions, the latter being further divided into non-algal (anap) and algal (aph) components. Our results showed that the diatom and dinoflagellate dominated sea-ice algal community responded to UVR down to 25-30 cm depth by increasing their MAA?:?chlorophyll-a ratio and by extending the composition of MAA pool from shinorine and palythine to porphyra-334 and an unknown compound with absorption peaks at ca. 335 and 360 nm. MAAs were the dominant absorbing components in algae in the top 10 cm of ice, and their contribution to total absorption became even more pronounced under UVR exposure. In addition to MAAs, the high absorption by chromophoric dissolved organic matter (CDOM) and by deposited atmospheric particles provided UV-protection for sea-ice organisms in the exposed ice. Efficient UV-protection will especially be of importance under the predicted future climate conditions with more frequent snow-free conditions. PMID:25837523

  8. Forecasting Bering Sea ice edge behavior

    SciTech Connect

    Pritchard, R.S. ); Mueller, A.C. ); Yang, Y.S. ); Hanzlick, D.J.

    1990-01-15

    A coupled ice/ocean dynamics model is developed to provide Arctic offshore operators with 5- to 7-day forecasts of ice motions, ice conditions, and ice edge motions. An adaptive grid is introduced to follow the ice edge, and the grid may move independently of the ice motion. The grid can be Lagrangian or Eulerian at different locations away from the ice edge. Ice stress is described using an elastic-plastic model with strength determined by the ice conditions. The ocean dynamics model describes time-dependent, three-dimensional behavior, including wind-driven currents and barotropic and baroclinic flows. The thermal energy budget of the ice cover is coupled to the ocean, with mass and salt interchange accompanying freezing or melting. Near the marginal ice zone (MIZ), surface winds (determined by reducing and turning the geostrophic winds) are enhanced to reflect observed behavior. The model was tested by simulating ice edge motions observed during the 1983 Marginal Ice Zone Experiment-West and during drilling of the 1983 north Aleutian shelf Continental Offshore Stratigraphic Test well. Simulations of ice edge movement in the Bering Sea compare with observed data to within about 5 km/d. The model correctly describes mixed-layer evolution in the marginal ice zone as fresh meltwater is mixed downward by turbulence. Along-edge baroclinic flows due to density gradients across the ice edge are simulated by the model, in agreement with observations. Increased ice drift speeds generate higher melt rates due to increased turbulence levels, with the result that ice edge advance is moderated in spite of higher ice drift speeds.

  9. Springtime coupling between chlorophyll a, sea ice and sea surface temperature in Disko Bay, West Greenland

    E-print Network

    Laidre, Kristin L.

    Author's personal copy Springtime coupling between chlorophyll a, sea ice and sea surface, 53°W) (using chlorophyll a concentrations as a proxy) under contrasting sea ice conditions in 2001 and 2003 (heavy sea ice) and 2002 and 2004 (light sea ice). Satellite-based observations of chlorophyll a

  10. Floating ice-algal aggregates below melting arctic sea ice.

    PubMed

    Assmy, Philipp; Ehn, Jens K; Fernández-Méndez, Mar; Hop, Haakon; Katlein, Christian; Sundfjord, Arild; Bluhm, Katrin; Daase, Malin; Engel, Anja; Fransson, Agneta; Granskog, Mats A; Hudson, Stephen R; Kristiansen, Svein; Nicolaus, Marcel; Peeken, Ilka; Renner, Angelika H H; Spreen, Gunnar; Tatarek, Agnieszka; Wiktor, Jozef

    2013-01-01

    During two consecutive cruises to the Eastern Central Arctic in late summer 2012, we observed floating algal aggregates in the melt-water layer below and between melting ice floes of first-year pack ice. The macroscopic (1-15 cm in diameter) aggregates had a mucous consistency and were dominated by typical ice-associated pennate diatoms embedded within the mucous matrix. Aggregates maintained buoyancy and accumulated just above a strong pycnocline that separated meltwater and seawater layers. We were able, for the first time, to obtain quantitative abundance and biomass estimates of these aggregates. Although their biomass and production on a square metre basis was small compared to ice-algal blooms, the floating ice-algal aggregates supported high levels of biological activity on the scale of the individual aggregate. In addition they constituted a food source for the ice-associated fauna as revealed by pigments indicative of zooplankton grazing, high abundance of naked ciliates, and ice amphipods associated with them. During the Arctic melt season, these floating aggregates likely play an important ecological role in an otherwise impoverished near-surface sea ice environment. Our findings provide important observations and measurements of a unique aggregate-based habitat during the 2012 record sea ice minimum year. PMID:24204642

  11. Processes driving sea ice variability in the Bering Sea in an eddying ocean/sea ice model: Mean seasonal cycle

    NASA Astrophysics Data System (ADS)

    Li, Linghan; McClean, Julie L.; Miller, Arthur J.; Eisenman, Ian; Hendershott, Myrl C.; Papadopoulos, Caroline A.

    2014-12-01

    The seasonal cycle of sea ice variability in the Bering Sea, together with the thermodynamic and dynamic processes that control it, are examined in a fine resolution (1/10°) global coupled ocean/sea-ice model configured in the Community Earth System Model (CESM) framework. The ocean/sea-ice model consists of the Los Alamos National Laboratory Parallel Ocean Program (POP) and the Los Alamos Sea Ice Model (CICE). The model was forced with time-varying reanalysis atmospheric forcing for the time period 1970-1989. This study focuses on the time period 1980-1989. The simulated seasonal-mean fields of sea ice concentration strongly resemble satellite-derived observations, as quantified by root-mean-square errors and pattern correlation coefficients. The sea ice energy budget reveals that the seasonal thermodynamic ice volume changes are dominated by the surface energy flux between the atmosphere and the ice in the northern region and by heat flux from the ocean to the ice along the southern ice edge, especially on the western side. The sea ice force balance analysis shows that sea ice motion is largely associated with wind stress. The force due to divergence of the internal ice stress tensor is large near the land boundaries in the north, and it is small in the central and southern ice-covered region. During winter, which dominates the annual mean, it is found that the simulated sea ice was mainly formed in the northern Bering Sea, with the maximum ice growth rate occurring along the coast due to cold air from northerly winds and ice motion away from the coast. South of St Lawrence Island, winds drive the model sea ice southwestward from the north to the southwestern part of the ice-covered region. Along the ice edge in the western Bering Sea, model sea ice is melted by warm ocean water, which is carried by the simulated Bering Slope Current flowing to the northwest, resulting in the S-shaped asymmetric ice edge. In spring and fall, similar thermodynamic and dynamic patterns occur in the model, but with typically smaller magnitudes and with season-specific geographical and directional differences.

  12. Seasonal variations in N and O isotopes of nitrate in snow at Summit, Greenland: Implications for the study of nitrate in snow and ice cores

    E-print Network

    Sigman, Daniel M.

    Seasonal variations in N and O isotopes of nitrate in snow at Summit, Greenland: Implications for the study of nitrate in snow and ice cores Meredith G. Hastings Department of Geosciences, Princeton measured in snow and firn from Summit, Greenland. The 15 N/14 N and 18 O/16 O ratios of NO3 À in recently

  13. Mapping daily snow//ice shortwave broadband albedo from Moderate Resolution Imaging Spectroradiometer (MODIS): The improved

    E-print Network

    Liang, Shunlin

    variable in surface energy balance calculations. The Moderate Resolution Imaging Spectroradiometer (MODIS (Moderate Resolution Imaging Spectroradiometer) Level 1B data to derive the albedo over Greenland. HoweverMapping daily snow//ice shortwave broadband albedo from Moderate Resolution Imaging

  14. A detailed assessment of snow accumulation in katabatic wind areas on the Ross Ice Shelf, Antarctica

    E-print Network

    Braaten, David A.

    1997-12-27

    An investigation of time dependent snow accumulation and erosion dynamics in a wind-swept environment was undertaken at two automatic weather stations sites on the Ross Ice Shelf between January 1994 and November 1995 using newly developed...

  15. ALBEDO MODELS FOR SNOW AND ICE ON A FRESHWATER LAKE. (R824801)

    EPA Science Inventory

    Abstract

    Snow and ice albedo measurements were taken over a freshwater lake in Minnesota for three months during the winter of 1996¯1997 for use in a winter lake water quality model. The mean albedo of new snow was measured as 0.83±0.028, while the...

  16. EOS Aqua AMSR-E Arctic Sea-Ice Validation Program: Arctic2006 Aircraft Campaign Flight Report

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Markus, T.

    2006-01-01

    In March 2006, a coordinated Arctic sea-ice validation field campaign using the NASA Wallops P-3B aircraft was successfully completed. This campaign was the second Alaskan Arctic field campaign for validating the Earth Observing System (EOS) Aqua Advanced Microwave Scanning Radiometer (AMSR-E) sea-ice products. The first campaign was completed in March 2003. The AMSR-E, designed and built by the Japanese Space Agency for NASA, was launched May 4, 2002 on the EOS Aqua spacecraft. The AMSR-E sea-ice products to be validated include sea-ice concentration, sea-ice temperature, and snow depth on sea ice. The focus of this campaign was on the validation of snow depth on sea ice and sea-ice temperature. This flight report describes the suite of instruments flown on the P-3, the objectives of each of the six flights, the Arctic regions overflown, and the coordination among satellite, aircraft, and surface-based measurements.

  17. Operation IceBridge: Sea Ice Interlude - Duration: 2 minutes, 36 seconds.

    NASA Video Gallery

    Sea ice comes in an array of shapes and sizes and has its own ephemeral beauty. Operation IceBridge studies sea ice at both poles, and also runs across interesting formations en route to other targ...

  18. Development of a Seismic Snow Streamer and Use of Multi- Offset Reflection for Determining Glacier Ice Properties

    NASA Astrophysics Data System (ADS)

    Velez Gonzalez, Jose A.

    Glaciers and ice sheets are important to climate research due to their role in controlling worldwide weather and temperature patterns as well as their potential impact in sea level rise. Because of this, scientists are attempting to model large ice sheets and important fast flowing glaciers. These models are limited in large part to the lack of data which govern the nonlinear behavior of ice flow. Seismic data acquisition can provide high resolution data which can be used to extract information of variables like bed topography, ice temperature and preferred ice crystal orientation. But seismic data acquisition in polar environments is challenging. This is mainly due to the labor intensive process of manually hand planting geophones. In order to improve the efficiency of active source seismic reflection data acquisition in polar environments, two prototype seismic snow-streamers were constructed for this investigation and optimized for deployment in remote locations. The first snow-streamer (experimental snow-streamer) was field tested in the Jakobshavn Glacier located in central western Greenland. The experimental snow-streamer was equipped with multiple geophone configurations and two plate materials. Twenty-two variable angle records were collected using the stationary snow streamer in the center of the survey. The source consisted of 0.5 kg of explosives buried 10 m below the snow surface at 160 m intervals. The resultant data set consisted of offsets ranging from -1760 to +1600 m and the ice-bed interface as well as two internal ice layers were imaged at approximately 1.85, 1.5 and 1.7 km depth respectively. The snow-streamer data was simultaneously collected with a mirror arrangement of hand planted buried geophones in order to test for the effects of plate weight, wind noise, geophone burial and plate to snow coupling in the seismic signal. The signal analysis and the comparison of streamer vs. buried geophones showed that geophone burial can degrade the seismic signal while the wind and signal analysis revealed that the best snow-streamer configuration was a combination of aluminum plates with vertical geophones. Using these results a second 480m full scale snow-streamer was tested in the Thwaites Glacier Antarctica. The snow-streamer data was simultaneously collected with a mirrored arrangement of surface planted and buried geophones. The trace by trace comparison revealed higher signal to noise in the data collected using the snow-streamer when compared to the surface planted and buried geophones. The full scale snow-streamer was easy to maneuver, very light and could be pulled in speeds up to 15 km/h. The use of the snow-streamer proved to be an efficient data acquisition tool, yielding high quality data. Therefore the use of snow-streamers can represent a significant improvement in the efficiency of seismic data acquisition in polar environments opening the possibility of determining important ice column properties for areas of interest. An important parameter affecting glacier flow is preferred ice crystal orientation. Seismic waves in ice travel up to 5% faster along the c-axis than when travelling perpendicular to it. Therefore, reflected seismic wave slowness (inverse of the velocity) variability as a function of angle of incidence can be used to detect anisotropy in ice crystal orientation. By combining the multi-offset seismic reflection data set acquired with the experimental snow-streamer and a 2D seismic reflection profile simultaneously collected for the same location, we investigated the presence of preferred ice crystal orientation for the area of study on the Jakobshavn Glacier. The combination of both data sets allowed the approximation of the average ray velocity as a function of angle of incidence. Given that the seismic velocity varies as a function of ice crystal orientation, we can use an existing model to relate the variation of seismic velocity as a function of offset to estimate the mean ice crystal orientation for the bed and imaged internal layers in terms of a conical c-axes distributi

  19. Low-frequency variability in the arctic atmosphere, sea ice, and upper-ocean climate system

    SciTech Connect

    Bitz, C.M.; Battisti, D.S.; Moritz, R.E.; Beesley, J.A.

    1996-02-01

    The low-frequency natural variability of the arctic climate system is modeled using a single-column, energy balance model of the atmosphere, sea ice, and upper-ocean system. Variability in the system is induced by forcing with realistic, random perturbations in the atmospheric energy transport and cloudiness. The model predicts that the volume of perennial sea ice varies predominantly on decadal timescales, while other arctic climate variables vary mostly on intraannual and interannual timescales. The variance of the simulated sea ice volume is most sensitive to perturbations of the atmospheric forcing in late spring, at the onset of melt. The variance of the simulated sea ice volume is most sensitive to perturbations of the atmospheric forcing in the late spring, at the onset of melt. The variance of sea ice volume increases with the mean sea ice thickness and with the number of layers resolved in the sea ice model. This suggests that much of the simulated variance develops when the surface temperature decouples from the sea ice interior during the late spring, when melting snow abruptly exposes the sea ice surface and decreases the surface albedo. The minimum model requirements to simulate the natural variability in the arctic climate are identified. The implications of the low-frequency, natural variability in sea ice volume for detecting a climate change are discussed. Finally, calculations suggest that the variability in the thermodynamic forcing of the polar cap could lead to a freshening in North Atlantic that is comparable to the freshening associated with the Great Salinity Anomaly. 28 refs., 14 figs., 5 tabs.

  20. The central role of diminishing sea ice in recent Arctic temperature amplification.

    PubMed

    Screen, James A; Simmonds, Ian

    2010-04-29

    The rise in Arctic near-surface air temperatures has been almost twice as large as the global average in recent decades-a feature known as 'Arctic amplification'. Increased concentrations of atmospheric greenhouse gases have driven Arctic and global average warming; however, the underlying causes of Arctic amplification remain uncertain. The roles of reductions in snow and sea ice cover and changes in atmospheric and oceanic circulation, cloud cover and water vapour are still matters of debate. A better understanding of the processes responsible for the recent amplified warming is essential for assessing the likelihood, and impacts, of future rapid Arctic warming and sea ice loss. Here we show that the Arctic warming is strongest at the surface during most of the year and is primarily consistent with reductions in sea ice cover. Changes in cloud cover, in contrast, have not contributed strongly to recent warming. Increases in atmospheric water vapour content, partly in response to reduced sea ice cover, may have enhanced warming in the lower part of the atmosphere during summer and early autumn. We conclude that diminishing sea ice has had a leading role in recent Arctic temperature amplification. The findings reinforce suggestions that strong positive ice-temperature feedbacks have emerged in the Arctic, increasing the chances of further rapid warming and sea ice loss, and will probably affect polar ecosystems, ice-sheet mass balance and human activities in the Arctic. PMID:20428168

  1. NASA Team 2 Sea Ice Concentration Algorithm Retrieval Uncertainty

    NASA Technical Reports Server (NTRS)

    Brucker, Ludovic; Cavalieri, Donald J.; Markus, Thorsten; Ivanoff, Alvaro

    2014-01-01

    Satellite microwave radiometers are widely used to estimate sea ice cover properties (concentration, extent, and area) through the use of sea ice concentration (IC) algorithms. Rare are the algorithms providing associated IC uncertainty estimates. Algorithm uncertainty estimates are needed to assess accurately global and regional trends in IC (and thus extent and area), and to improve sea ice predictions on seasonal to interannual timescales using data assimilation approaches. This paper presents a method to provide relative IC uncertainty estimates using the enhanced NASA Team (NT2) IC algorithm. The proposed approach takes advantage of the NT2 calculations and solely relies on the brightness temperatures (TBs) used as input. NT2 IC and its associated relative uncertainty are obtained for both the Northern and Southern Hemispheres using the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) TB. NT2 IC relative uncertainties estimated on a footprint-by-footprint swath-by-swath basis were averaged daily over each 12.5-km grid cell of the polar stereographic grid. For both hemispheres and throughout the year, the NT2 relative uncertainty is less than 5%. In the Southern Hemisphere, it is low in the interior ice pack, and it increases in the marginal ice zone up to 5%. In the Northern Hemisphere, areas with high uncertainties are also found in the high IC area of the Central Arctic. Retrieval uncertainties are greater in areas corresponding to NT2 ice types associated with deep snow and new ice. Seasonal variations in uncertainty show larger values in summer as a result of melt conditions and greater atmospheric contributions. Our analysis also includes an evaluation of the NT2 algorithm sensitivity to AMSR-E sensor noise. There is a 60% probability that the IC does not change (to within the computed retrieval precision of 1%) due to sensor noise, and the cumulated probability shows that there is a 90% chance that the IC varies by less than +/-3%. We also examined the daily IC variability, which is dominated by sea ice drift and ice formation/melt. Daily IC variability is the highest, year round, in the MIZ (often up to 20%, locally 30%). The temporal and spatial distributions of the retrieval uncertainties and the daily IC variability is expected to be useful for algorithm intercomparisons, climate trend assessments, and possibly IC assimilation in models.

  2. Distinguishing snow and ice melt contributions using daily MODIS and a temperature index melt model in the Hunza River basin

    NASA Astrophysics Data System (ADS)

    Rittger, Karl; Brodzik, Mary J.; Racoviteanu, Adina; Barrett, Andrew; Jodha Kalsa, Siri; Armstrong, Richard

    2015-04-01

    In mountainous regions of High Asia, snow and ice both contribute to streamflow, but few in-situ observations exist that can help distinguish between the two components of melt. Our goal is to develop a melt model that can distinguish between seasonal snow and glacier ice melt at a continental scale. We use a combination of MODIS-derived data sets to distinguish three surface types at daily resolution: 1) exposed glacier ice, 2) snow over ice and 3) snow over land. We use MODICE to map glacier area and then distinguish areas of exposed ice from snow over ice using thresholds on MODIS-derived albedo or grain size products. We map snow over land using the daily MODSCAG fractional snow cover product, and use the time series of three surface types as input to a temperature index melt model. The model outputs melt volumes from exposed glacier ice, snow over ice and snow over land, respectively. To partition the glacier surface into exposed glacier ice versus snow over ice, we threshold MODIS albedo or grain size based on higher-resolution Landsat 8 imagery. During the ablation period, the high elevation mid-latitude snowpack receives intense incoming solar radiation resulting in surface albedo decreases and snow grain growth. We compare differences in modeled melt using two albedo products (Terra Daily Snow Cover algorithm (MOD10A1) and Surface Reflectance BRDF/Albedo (MCD43)) and two grain size products (MODIS Snow Covered Area and Grain Size Model (MODSCAG) and MODIS Dust Radiative Forcing in Snow (MODDRFS)). For the Hunza basin, a sub-basin of the Upper Indus basin, for the years 2001-2004, the modeled melt from exposed glacier ice accounts for: 26-44% (MOD10A1 albedo), 24-32% (MCD43 albedo), 17-28% (MODSCAG grain size) or 23-26% (MODDRFS grain size) of the combined melt from all three surface areas.

  3. Snow Cover Effects on Glacier Ice Surface Temperature Margherita Maggioni*{

    E-print Network

    Williams, Mark W.

    of rounded crystals originated by melt-freeze metamorphism, while in the season poor in snow depth hoar and faceted crystals prevailed, due to the higher temperature gradient. From these two winter seasons­2006, the shallow depth of snow did not allow basal temperature to reach an equilibrium value and the snow

  4. Snow-ice-tephra-lava interactions during the 2010 Fimmvorduhals eruption

    NASA Astrophysics Data System (ADS)

    Haklar, J.; Edwards, B. R.; Gudmundsson, M. T.

    2010-12-01

    On March 20th a small basaltic fissure opened at the northern edge of Fimmvorduhals, a popular hiking pass between Eyjafjallajökull, to the west, and Myrdalsjökull, to the east. Immediately prior to the eruption, the vent area was covered with typically 1-3 meters of snow and locally snow-covered, isolated remnants of glacial ice. Fieldwork conducted during June and July documented evidence for a variety of different types of interactions between volcanism (tephra and lava) and snow/ice, including direct contact (e.g. ash-covered snow, lava blocks on snow/ice, lava flows on ash-covered snow), indirect melting (e.g. arcuate snow/ice melting patterns at lava flow fronts, partly collapsed sheet lava flows), and the formation of small bomb-cored mounds via post-depositional snow melting. Many of these features are likely ephemeral, and may leave no trace in the geological record; however under certain circumstances they may leave subtle clues that could aide in identifying the presence of snow during eruptions. The field relationships documented are consistent with varied mechanisms of heat transfer during the eruption to the surrounding environment. The arcuate-shaped snow and ice-banks at the edges of flows appear to closely mimic the shape of the adjacent lava lobes. The geometric relationships are consistent with snow/ice melting several meters in front of the advancing flows by radiant heat from the front of the lava lobes. Also, in at least two areas we observed features that are consistent with snow melting beneath lava, possibly by slower heat conduction. One example is a small cave beneath the lava at the lava-snow contact. The other is a ~1 m thick sheet flow that has partly collapsed, forming a fracture that appears to have been controlled by incipient polygonal jointing; melting of underlying snow may have undermined part of the sheet flow based and facilitated its collapse. However, under at least two separate types of conditions lava seems to have little impact on snow/ice. Firstly, where lava flows onto the coarse apron of lapilli generated during the early part of the eruption, the lapilli layer (~13 cm thick) appears to have insulated the snow and prevented it from melting noticeably. Secondly, towards the distal ends of the flows, blocks of lava were heaved onto bounding snow/ice without producing noticeable melting. The bomb-cored mounds, which are the most evocative structures formed by tephra-snow interactions, are also probably the least likely to be preserved. The mounds appear to have formed by a complex sequence of events, and their stratigraphy, from bottom to top, is: snow, icy-snow, volcanic bomb, coarse black lapilli, and medium- to fine, greenish-gray ash. The mounds appear to record melting and deflation of the snow surface sometime after the deposition of the ash layer, which probably originated from the summit vent at Eyjafjallajökull.

  5. Recent changes in Antarctic Sea Ice.

    PubMed

    Turner, John; Hosking, J Scott; Bracegirdle, Thomas J; Marshall, Gareth J; Phillips, Tony

    2015-07-13

    In contrast to the Arctic, total sea ice extent (SIE) across the Southern Ocean has increased since the late 1970s, with the annual mean increasing at a rate of 186×10(3)?km(2) per decade (1.5% per decade; p<0.01) for 1979-2013. However, this overall increase masks larger regional variations, most notably an increase (decrease) over the Ross (Amundsen-Bellingshausen) Sea. Sea ice variability results from changes in atmospheric and oceanic conditions, although the former is thought to be more significant, since there is a high correlation between anomalies in the ice concentration and the near-surface wind field. The Southern Ocean SIE trend is dominated by the increase in the Ross Sea sector, where the SIE is significantly correlated with the depth of the Amundsen Sea Low (ASL), which has deepened since 1979. The depth of the ASL is influenced by a number of external factors, including tropical sea surface temperatures, but the low also has a large locally driven intrinsic variability, suggesting that SIE in these areas is especially variable. Many of the current generation of coupled climate models have difficulty in simulating sea ice. However, output from the better-performing IPCC CMIP5 models suggests that the recent increase in Antarctic SIE may be within the bounds of intrinsic/internal variability. PMID:26032320

  6. The Secret of the Svalbard Sea Ice Barrier

    NASA Technical Reports Server (NTRS)

    Nghiem, Son V.; Van Woert, Michael L.; Neumann, Gregory

    2004-01-01

    An elongated sea ice feature called the Svalbard sea ice barrier rapidly formed over an area in the Barents Sea to the east of Svalbard posing navigation hazards. The secret of its formation lies in the bottom bathymetry that governs the distribution of cold Arctic waters masses, which impacts sea ice growth on the water surface.

  7. A mechanism for biologically-induced iodine emissions from sea-ice

    NASA Astrophysics Data System (ADS)

    Saiz-Lopez, A.; Blaszczak-Boxe, C. S.; Carpenter, L. J.

    2015-04-01

    Ground- and satellite-based measurements have reported high concentrations of iodine monoxide (IO) in coastal Antarctica. The sources of such a large iodine burden in the coastal Antarctic atmosphere remain unknown. We propose a mechanism for iodine release from sea-ice based on the premise that micro-algae are the primary source of iodine emissions in this environment. The emissions are triggered by the biological production of iodide (I-) and hypoiodous acid (HOI) from micro-algae (contained within and underneath sea-ice) and their diffusion through sea-ice brine channels, to accumulate in the quasi-liquid layer (QLL) on the surface of sea-ice. Prior to reaching the QLL, the diffusion timescale of iodine within sea-ice is depth-dependent. The QLL is also a vital component of the proposed mechanism as it enhances the chemical kinetics of iodine-related reactions, which allows for the efficient release of iodine to the polar boundary layer. We suggest iodine is released to the atmosphere via 3 possible pathways: (1) emitted from the QLL and then transported throughout snow atop sea-ice, to be released to the atmosphere, (2) released directly from the QLL to the atmosphere in regions of sea-ice that are not covered with snowpack; or (3) emitted to the atmosphere directly through fractures in the sea-ice pack. To investigate the proposed biology-ice-atmosphere coupling at coastal Antarctica we use a multiphase model that incorporates the transport of iodine species, via diffusion, at variable depths, within brine channels of sea-ice. Model simulations were conducted to interpret observations of elevated springtime IO in the coastal Antarctic, around the Weddell Sea. The results show that the levels of inorganic iodine (i.e., I2, IBr, ICl) released from sea-ice through this mechanism could account for the observed IO concentrations during this timeframe. The model results also indicate that iodine may trigger the catalytic release of bromine from sea-ice through phase equilibration of IBr. We propose that this mechanism may also result in the emission of iodocarbons from the sea-ice to the polar atmosphere. Considering the extent of sea-ice around the Antarctic continent, we suggest that the resulting high levels of iodine may have widespread impacts on catalytic ozone destruction and aerosol formation in the Antarctic lower troposphere.

  8. Summer Sea ice in the Pacific Arctic sector from the CHINARE-2010 cruise

    NASA Astrophysics Data System (ADS)

    Ackley, S. F.; Xie, H.; Lei, R.; Huang, W.; Chinare 2010 Arctic Sea Ice Group

    2010-12-01

    The Fourth Chinese National Arctic Research Expedition (CHINARE) from July 1 to Sep. 23, 2010, the last Chinese campaign in Arctic Ocean contributing to the fourth International Polar Year (IPY), conducted comprehensive scientific studies on ocean-ice-atmosphere interaction and the marine ecosystem’s response to climatic change in Arctic. This paper presents an overview on sea ice (ice concentration, floe size, melt pond coverage, sea ice and snow thickness) of the Pacific Arctic sector, in particular between 150°W to 180°W to 86°N, based on: (1) underway visual observations of sea ice at half-hourly and automatic cameras recording (both side looking from the icebreaker R.V. Xuelong) every 10 to 15 seconds; (2) a downward-looking video mounted on the left side of the vessel at a height of 7 m above waterline recording overturning of ice floes; (3) on-site measurements of snow and ice thickness using drilling and electromagnetic instrument EM31 (9.8 kHz) at eight short-term (~3 hours each) and one 12-day ice stations; (4) six flights of aerial photogrammetry from helicopter, and (5) Satellite data (AMSE-E ice concentration and ENVISAT ASAR) and NIC ice charts) that extended the observations/measurements along beyond the ship track and airborne flights. In the northward leg, the largest ice concentration zone was in the area starting from ~75°N (July 29), with ice concentration of 60-90% (mean ~80%), ice thickness of 1.5-2m, melt ponds of 10-50% of ice, ridged ice of 10-30% of ice, and floe size of 100’s meters to kms. The 12-day ice station (from Aug 7-19), started at 86.92°N/178.88°W and moved a total of 175.7km, was on an ice floe over 100 km2 in size and ~2 m in mean thickness. There were two heavy and several slight snowfall events in the period (July 29 to Aug 19). Snow thickness varies from 5cm to 15 cm, and melted about 5cm during the 12-day ice camp. In the southward leg, the largest sea ice concentration zone was in the area between 87°N to 80°N (from August 21 to August 24). In this area, the ice concentration varied from 70-100%, melt pond varied from 20-50% of ice, ridged ice varied from 10-30% of ice, and floe size was dominated by 10’s km to several km’s in one or two dimensions. The overall ice thickness decreased southward from 1.8-2m to 0.6-1m. The ice type of the area is multiyear ice dominated, with small portion of first year ice. In the area from ~85°N to 83.5°N, we see dirty ice (brownish, rich hills and valleys, mostly multiyear ice), varying from 10-20% of ice. Similar dirty ice was only seen from 72°N-75°N in the northward leg (July 24-29), then not seen until the northern region. The ice situation in this cruise will be compared with that from the CHINARE-2008 cruise, in a similar area and season, so change of the two years for this sector of Arctic Ocean during the middle-later summer can be deduced.

  9. Ice in Caspian Sea and Aral Sea, Kazakhstan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this MODIS image from December 3, 2001, winter sea ice can be seen forming in the shallow waters of the northern Caspian (left) and Aral (upper right) Seas. Despite the inflow of the Volga River (upper left), the northern portion of the Caspian Sea averages only 17 ft in depth, and responds to the region's continental climate, which is cold in winter and hot and dry in the summer. The southern part of the Sea is deeper and remains ice-free throughout the winter. The dirty appearance of the ice may be due to sediment in the water, but may also be due to wind-driven dust. The wind in the region can blow at hurricane-force strength and can cause the ice to pile up in hummocks that are anchored to the sea bottom. The eastern portion of the Aral Sea is also beginning to freeze. At least two characteristics of the Aral Sea 'compete' in determining whether its waters will freeze. The Sea is shallow, which increases the likelihood of freezing, but it is also very salty, which means that lower temperatures are required to freeze it than would be required for fresh water. With average December temperatures of 18o F, it's clearly cold enough to allow ice to form. As the waters that feed the Aral Sea continue to be diverted for agriculture, the Sea becomes shallower and the regional climate becomes even more continental. This is because large bodies of water absorb and retain heat, moderating seasonal changes in temperature. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  10. Fram Strait sea ice outflow

    NASA Technical Reports Server (NTRS)

    Kwok, R.; Cunningham, G. F.; Pang, S. S.

    2004-01-01

    We summarize 24 years of ice export estimates and examine, over a 9-year record, the associated variability in the time-varying upward-looking sonar (ULS) thickness distributions of the Fram Strait. A more thorough assessment of the PMW (passive microwave) ice motion with 5 years of synthetic aperture radar (SAR)observations shows the uncertainties to be consistent with that found by Kwok and Rothrock [1999], giving greater confidence to the record of ice flux calculations.

  11. Arctic Sea Ice : Trends, Stability and Variability

    NASA Astrophysics Data System (ADS)

    Moon, W.; Wettlaufer, J. S.

    2014-12-01

    A stochastic Arctic sea-ice model is derived and analysed in detail to interpret the recent decay and associated variability of Arctic sea-ice under changes in radiative forcing. The approach begins from a deterministic model of the heat flux balance through the air/sea/ice system, which uses observed monthly-averaged heat fluxesto drive a time evolution of sea-ice thickness. This model reproduces the observed seasonal cycle of the ice cover and it is to this that stochastic noise--representing high frequency variability--is introduced.The model takes the form of a single periodic non-autonomous stochastic ordinary differential equation. The value of such a model is that it provides a relatively simple framework to examine the role of noise in the basic nonlinear interactions at play as transitions in the state of the ice cover (e.g., from perennial to seasonal) are approached. Moreover, the stability and the noise conspire to underlie the inter annual variability and how that variability changes as one approaches the deterministic bifurcations in the system.

  12. The effect of sea ice on the solar energy budget in the astmosphere-sea ice-ocean system: A model study

    NASA Technical Reports Server (NTRS)

    Jin, Z.; Stamnes, Knut; Weeks, W. F.; Tsay, Si-Chee

    1994-01-01

    A coupled one-dimensional multilayer and multistream radiative transfer model has been developed and applied to the study of radiative interactions in the atmosphere, sea ice, and ocean system. The consistent solution of the radiative transfer equation in this coupled system automatically takes into account the refraction and reflection at the air-ice interface and allows flexibility in choice of stream numbers. The solar radiation spectrum (0.25 micron-4.0 micron) is divided into 24 spectral bands to account adequately for gaseous absorption in the atmosphere. The effects of ice property changes, including salinity and density variations, as well as of melt ponds and snow cover variations over the ice on the solar energy distribution in the entire system have been studied quantitatively. The results show that for bare ice it is the scattering, determined by air bubbles and brine pockets, in just a few centimeters of the top layer of ice that plays the most important role in the solar energy absorption and partitioning in the entire system. Ice thickness is important to the energy distribution only when the ice is thin, while the absorption in the atmosphere is not sensitive to ice thickness exceeds about 70 cm. The presence of clouds moderates all the sensitivities of the absorptive amounts in each layer to the variations in the ice properties and ice thickness. Comparisons with observational spectral albedo values for two simple ice types are also presented.

  13. Evaluate the application of ERTS-A data for detecting and mapping sea ice

    NASA Technical Reports Server (NTRS)

    Barnes, J. C. (principal investigator)

    1973-01-01

    The author has identified the following significant results. Sea ice is detectable in all of the ERTS-1 MSS bands and can be distinguished from clouds through a number of interpretive keys. Considerable information on ice type can be derived from the ERTS-1 data. Ice types that appear to be identifiable include: ice floes of various categories, pack ice of various concentrations, ice belts, brash ice, rotten ice, fast ice, leads, fractures, cracks, puddles, thaw holes, and flooded ice. Although larger icebergs can be seen, it is difficult to distinguish them from ice floes. Ice features as small as the small floe of 20 to 100 m across can be detected, and the sizes of features somewhat smaller than 100 m can be measured from enlarged ERTS-1 prints. The multispectral analysis of the ERTS-1 MSS-7 bands provides much information on ice type and ice surface features that cannot be derived from a single spectral band. For example, thaw holes can often be distinguished from puddles because of their different appearances in the two bands. These surface features can be indicative of ice age. Furthermore, snow lines on glaciers can be reliably mapped through the joint use of the MSS-4 and 7 data.

  14. Laser Altimetry Sampling Strategies over Sea Ice

    NASA Technical Reports Server (NTRS)

    Farrell, Sinead L.; Markus, Thorsten; Kwok, Ron; Connor, Laurence

    2011-01-01

    With the conclusion of the science phase of the Ice, Cloud and land Elevation Satellite (ICESat) mission in late 2009, and the planned launch of ICESat-2 in late 2015, NASA has recently established the IceBridge program to provide continuity between missions. A major goal of IceBridge is to obtain a sea-ice thickness time series via airborne surveys over the Arctic and Southern Oceans. Typically two laser altimeters, the Airborne Topographic Mapper (ATM) and the Land, Vegetation and Ice Sensor (LVIS), are utilized during IceBridge flights. Using laser altimetry simulations of conventional analogue systems such as ICESat, LVIS and ATM, with the multi-beam system proposed for ICESat-2, we investigate differences in measurements gathered at varying spatial resolutions and the impact on sea-ice freeboard. We assess the ability of each system to reproduce the elevation distributions of two seaice models and discuss potential biases in lead detection and sea-surface elevation, arising from variable footprint size and spacing. The conventional systems accurately reproduce mean freeboard over 25km length scales, while ICESat-2 offers considerable improvements over its predecessor ICESat. In particular, its dense along-track sampling of the surface will allow flexibility in the algorithmic approaches taken to optimize the signal-to-noise ratio for accurate and precise freeboard retrieval.

  15. A new algorithm to measure sea ice concentration from passive microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Repina, Irina; Sharkov, Evgeniy; Komarova, Nataliya; Raev, Mikhail; Tikhonov, Vasilii; Boyarskiy, Dmitriy

    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. One of the error sources is the current practice of using empirical dependencies and adjustment coefficients for the retrieval of ice characteristics and neglecting the physics of the process. We discuss an electrodynamic model of the sea surface - sea ice - snow cover - atmosphere system developed with account taken of physical and structural properties of the ambient. Model calculations of ice brightness temperature in different concentrations and snow covers are in good agreement with SSM/I measurement data. On the base of this model we develop a new algorithm for the retrieval of sea ice concentration from passive microwave sensing data - Variation Arctic Sea Ice Algorithm (VASIA). In contrast to the well-known techniques (NASA TEAM, Bootstrap, ASI, NORSEX et al), it takes into account the real physical parameters of ice, snow and open water rather than empirical and adjustment coefficients. Satellite data were provided by the POLE-RT-Fields SSM/I and SSMIS data collection for polar regions retrieved from the GLOBAL-RT database. The results of the proposed algorithm for Arctic ice cover concentration are compared to NASA-TEAM2 technique. The proposed algorithm of sea ice concentration retrieval from microwave radiometry data gives good results within the assumed approximations. Lower ice concentration produced by VASIA for September is related to the problem of melt ponds (pools of open water on sea ice). 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. Emission from melt ponds corresponds to that of open water resulting in significant underestimating of ice concentration in summer. The work was sponsored by RFBR projects N 13-05-00272 and N 13-05- 41443 as well as the Russian Federation Governmental grant (Agreement N 11.G34.31.0078) for investigations guided by outstanding scientists.

  16. Towards Improving Sea Ice Predictabiity: Evaluating Climate Models Against Satellite Sea Ice Observations

    NASA Astrophysics Data System (ADS)

    Stroeve, J. C.

    2014-12-01

    The last four decades have seen a remarkable decline in the spatial extent of the Arctic sea ice cover, presenting both challenges and opportunities to Arctic residents, government agencies and industry. After the record low extent in September 2007 effort has increased to improve seasonal, decadal-scale and longer-term predictions of the sea ice cover. Coupled global climate models (GCMs) consistently project that if greenhouse gas concentrations continue to rise, the eventual outcome will be a complete loss of the multiyear ice cover. However, confidence in these projections depends o HoHoweon the models ability to reproduce features of the present-day climate. Comparison between models participating in the World Climate Research Programme Coupled Model Intercomparison Project Phase 5 (CMIP5) and observations of sea ice extent and thickness show that (1) historical trends from 85% of the model ensemble members remain smaller than observed, and (2) spatial patterns of sea ice thickness are poorly represented in most models. Part of the explanation lies with a failure of models to represent details of the mean atmospheric circulation pattern that governs the transport and spatial distribution of sea ice. These results raise concerns regarding the ability of CMIP5 models to realistically represent the processes driving the decline of Arctic sea ice and to project the timing of when a seasonally ice-free Arctic may be realized. On shorter time-scales, seasonal sea ice prediction has been challenged to predict the sea ice extent from Arctic conditions a few months to a year in advance. Efforts such as the Sea Ice Outlook (SIO) project, originally organized through the Study of Environmental Change (SEARCH) and now managed by the Sea Ice Prediction Network project (SIPN) synthesize predictions of the September sea ice extent based on a variety of approaches, including heuristic, statistical and dynamical modeling. Analysis of SIO contributions reveals that when the September sea ice extent is near the long-term trend, contributions tend to be accurate. Years when the observed extent departs from the trend have proven harder to predict. Predictability skill does not appear to be more accurate for dynamical models over statistical ones, nor is there a measurable improvement in skill as the summer progresses.

  17. Waveform classification of airborne synthetic aperture radar altimeter over Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Zygmuntowska, M.; Khvorostovsky, K.; Helm, V.; Sandven, S.

    2013-08-01

    Sea ice thickness is one of the most sensitive variables in the Arctic climate system. In order to quantify changes in sea ice thickness, CryoSat-2 was launched in 2010 carrying a Ku-band radar altimeter (SIRAL) designed to measure sea ice freeboard with a few centimeters accuracy. The instrument uses the synthetic aperture radar technique providing signals with a resolution of about 300 m along track. In this study, airborne Ku-band radar altimeter data over different sea ice types have been analyzed. A set of parameters has been defined to characterize the differences in strength and width of the returned power waveforms. With a Bayesian-based method, it is possible to classify about 80% of the waveforms from three parameters: maximum of the returned power waveform, the trailing edge width and pulse peakiness. Furthermore, the maximum of the power waveform can be used to reduce the number of false detections of leads, compared to the widely used pulse peakiness parameter. For the pulse peakiness the false classification rate is 12.6% while for the power maximum it is reduced to 6.5%. The ability to distinguish between different ice types and leads allows us to improve the freeboard retrieval and the conversion from freeboard into sea ice thickness, where surface type dependent values for the sea ice density and snow load can be used.

  18. Waveform analysis of airborne synthetic aperture radar altimeter over Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Zygmuntowska, M.; Khvorostovsky, K.; Helm, V.; Sandven, S.

    2013-03-01

    Sea ice thickness is one of the most sensitive variables in the Arctic climate system. In order to quantify changes in sea ice thickness, CryoSat was launched in 2010 carrying a Ku-band Radar Altimeter (SIRAL) designed to measure sea ice freeboard with a few centimeters accuracy. The instrument uses the synthetic aperture radar technique providing signals with a resolution of about 300 m along track. In this study, airborne Ku-band radar altimeter data over different sea ice types has been analyzed. A set of parameters has been defined to characterize the difference in strength and width of the returned power waveforms. With a Bayesian based method it is possible to classify about 80% of the waveforms by three parameters: maximum of the returned power echo, the trailing edge width and pulse peakiness. Furthermore, the radar power echo maximum can be used to minimize the rate of false detection of leads compared to the widely used Pulse Peakiness parameter. The possibility to distinguish between different ice types and open water allows to improve the freeboard retrieval and the conversion into sea ice thickness where surface type dependent values for the sea ice density and snow load can be used.

  19. Impacts of Recent Perennial Sea Ice Reduction on BrO Observations at Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    Peterson, P.; Simpson, W. R.; Donohoue, D.; Nghiem, S. V.; Friess, U.; Platt, U.

    2013-12-01

    Polar sunrise in the Arctic has been associated with production of reactive halogens from sea salt(e.g. Br, BrO). While effects of these halogen species are well known(e.g. ozone depletion, mercury deposition), their production is not fully understood, but thought to be linked to heterogeneous chemistry taking place on saline ice surfaces(e.g saline snow, first year sea ice). Given the recent decline of perennial sea ice in the Arctic, it is imperative to understand the role of younger, more saline, first year ice in halogen activation processes. We used multiple axis differential optical absorption spectroscopy(MAX-DOAS) at Barrow, Alaska to observe BrO during the spring/early summer of 2008,2009,2012, and 2013. While average BrO boundary layer vertical column densities(BL-VCD) agreed within error during 2008 and 2009, the average observed BL-VCD doubled from 1e13 mol/cm^2 in 2008 and 2009, to 2e13 mol/cm^2 in 2012. We explore potential explanations for this observed increase using satellite maps of synoptic sea ice classes, MODIS imagery of local sea ice features, and back trajectory modelling. Potential impacts of the 2012 record minimum sea ice extent on observed halogen activation during the spring of 2013 are also discussed.

  20. Visible and near-ultraviolet absorption spectrum of ice from transmission of solar radiation into snow

    E-print Network

    Warren, Stephen

    Visible and near-ultraviolet absorption spectrum of ice from transmission of solar radiation can be used to infer the spectral absorption coefficient of pure ice, by reference to a known value at 600 nm. The method is applied to clean Antarctic snow; the absorption minimum is at 390 nm

  1. Dynamic ikaite production and dissolution in sea ice - control by temperature, salinity and pCO2 conditions

    NASA Astrophysics Data System (ADS)

    Rysgaard, S.; Wang, F.; Galley, R. J.; Grimm, R.; Lemes, M.; Geilfus, N.-X.; Chaulk, A.; Hare, A. A.; Crabeck, O.; Else, B. G. T.; Campbell, K.; Papakyriakou, T.; Sørensen, L. L.; Sievers, J.; Notz, D.

    2013-12-01

    Ikaite is a hydrous calcium carbonate mineral (CaCO3 · 6H2O). It is only found in a metastable state, and decomposes rapidly once removed from near-freezing water. Recently, ikaite crystals have been found in sea ice and it has been suggested that their precipitation may play an important role in air-sea CO2 exchange in ice-covered seas. Little is known, however, of the spatial and temporal dynamics of ikaite in sea ice. Here we present evidence for highly dynamic ikaite precipitation and dissolution in sea ice grown at an out-door pool of the Sea-ice Environmental Research Facility (SERF). During the experiment, ikaite precipitated in sea ice with temperatures below -3 °C, creating three distinct zones of ikaite concentrations: (1) a mm to cm thin surface layer containing frost flowers and brine skim with bulk concentrations of > 2000 ?mol kg-1, (2) an internal layer with concentrations of 200-400 ?mol kg-1 and (3) a~bottom layer with concentrations of < 100 ?mol kg-1. Snowfall events caused the sea ice to warm, dissolving ikaite crystals under acidic conditions. Manual removal of the snow cover allowed the sea ice to cool and brine salinities to increase, resulting in rapid ikaite precipitation. The modeled (FREZCHEM) ikaite concentrations were in the same order of magnitude as observations and suggest that ikaite concentration in sea ice increase with decreasing temperatures. Thus, varying snow conditions may play a key role in ikaite precipitation and dissolution in sea ice. This will have implications for CO2 exchange with the atmosphere and ocean.

  2. Role of ice nucleation and antifreeze activities in pathogenesis and growth of snow molds.

    PubMed

    Snider, C S; Hsiang, T; Zhao, G; Griffith, M

    2000-04-01

    ABSTRACT We examined the ability of snow molds to grow at temperatures from -5 to 30 degrees C and to influence the growth of ice through assays for ice nucleation and antifreeze activities. Isolates of Coprinus psychromorbidus (low temperature basidiomycete variant), Microdochium nivale, Typhula phacorrhiza, T. ishikariensis, T. incarnata, and T. canadensis all grew at -5 degrees C, whereas Sclerotinia borealis and S. homoeocarpa did not grow at temperatures below 4 degrees C. The highest threshold ice nucleation temperature was -7 degrees C. Because snow molds are most damaging to their hosts at temperatures above this, our results imply that the pathogenesis of these fungi is not dependent on ice nucleation activity to cause freeze-wounding of host plants. All snow molds that grew at subzero temperatures also exhibited antifreeze activity in the growth medium and in the soluble and insoluble hyphal fractions, with the exception of M. nivale and one isolate of T. canadensis. The lack of high ice nucleation activity combined with the presence of antifreeze activity in all fungal fractions indicates that snow molds can moderate their environment to inhibit or modify intra- and extracellular ice formation, which helps explain their ability to grow at subzero temperatures under snow cover. PMID:18944584

  3. Potential Applications of Satellite Based Low Frequency Microwave Measurements of Snow and Ice

    NASA Technical Reports Server (NTRS)

    West, Richard D.

    2000-01-01

    In this presentation we will examine some potential applications of low frequency microwave radar and radiometer data to remote sensing of snow and ice conditions over land. We focus on the following low frequency bands; L-band (1.28 GHz), S-band (2.69 GHz), and C-band (5.0 GHz). To predict the effect of snow cover on microwave emission, we need to characterize the dielectric properties of the snow in terms of important physical parameters such as snow density, temperature, and wetness. For the case of dry snow, we use an empirical mixing formula which gives the effective complex permittivity of snow as a function of density, temperature, and frequency. For wet snow, we use another mixing formula which gives the effective complex permittivity as a function of snow wetness. With dry snow, the loss at low microwave frequencies is very small so the corresponding penetration depths are very large (eg., 100 m). Clearly seasonal snow covers are far too thin to have a direct scattering or emission effect on these low frequency bands. There are, however, indirect effects introduced because of altered reflection at the snow/soil boundary, and an extra reflecting interface at the snow/air boundary. For C-band, layers of snow with different densities can have an impact if the number of layers grows sufficiently large. (eg., many meters of snow pack with cm-scale density layering.) Wet snow poses a more difficult problem. Liquid water is much more effective than ice at scattering and absorbing L-band radiation, so even a small amount of wetness will greatly reduce penetration. For example, with a snow wetness of 1 percent (volume fraction), and a density of 300 kg/cu. m, the penetration depths for L-band, S-band, and C-band are about 1.6 m, 0.3 m, and 0.15 m respectively. Very wet snow has more than 10 percent liquid water, and the corresponding L-band penetration is less than 0.2 m. Because the penetration distance is a strong function of frequency, it may be possible to identify a particular class of snow where the wetness is a few percent, and the depth is around one meter by looking at the frequency gradient.

  4. A Supplementary Clear-Sky Snow and Ice Recognition Technique for CERES Level 2 Products

    NASA Technical Reports Server (NTRS)

    Radkevich, Alexander; Khlopenkov, Konstantin; Rutan, David; Kato, Seiji

    2013-01-01

    Identification of clear-sky snow and ice is an important step in the production of cryosphere radiation budget products, which are used in the derivation of long-term data series for climate research. In this paper, a new method of clear-sky snow/ice identification for Moderate Resolution Imaging Spectroradiometer (MODIS) is presented. The algorithm's goal is to enhance the identification of snow and ice within the Clouds and the Earth's Radiant Energy System (CERES) data after application of the standard CERES scene identification scheme. The input of the algorithm uses spectral radiances from five MODIS bands and surface skin temperature available in the CERES Single Scanner Footprint (SSF) product. The algorithm produces a cryosphere rating from an aggregated test: a higher rating corresponds to a more certain identification of the clear-sky snow/ice-covered scene. Empirical analysis of regions of interest representing distinctive targets such as snow, ice, ice and water clouds, open waters, and snow-free land selected from a number of MODIS images shows that the cryosphere rating of snow/ice targets falls into 95% confidence intervals lying above the same confidence intervals of all other targets. This enables recognition of clear-sky cryosphere by using a single threshold applied to the rating, which makes this technique different from traditional branching techniques based on multiple thresholds. Limited tests show that the established threshold clearly separates the cryosphere rating values computed for the cryosphere from those computed for noncryosphere scenes, whereas individual tests applied consequently cannot reliably identify the cryosphere for complex scenes.

  5. Polar Sea Ice Mapping Using SeaWinds Data Hyrum S. Anderson and David G. Long

    E-print Network

    Long, David G.

    Polar Sea Ice Mapping Using SeaWinds Data Hyrum S. Anderson and David G. Long Brigham Young for mapping polar sea ice extent. In this study, a new al- gorithm for polar sea ice mapping is developed for use with the SeaWinds instrument. The approach utilizes a priori information within the framework

  6. Snow algae in an ice core drilled on Grigoriev Ice cap in the Kyrgyz Tien Shen Mountains

    NASA Astrophysics Data System (ADS)

    Honda, M.; Takeuchi, N.; Sera, S.; Fujita, K.; Okamoto, S.; Naoki, K.; Aizen, V. B.

    2012-12-01

    Snow algae are photosynthetic microorganisms and are living on the surfase of glaciers. They grow on melting surface from spring to summer and their biomass and community structure are changed with physical and chemical conditions on glaciers. Ice cores drilled from glaciers also contain snow algae that grew in the past. Studying biomass and community structure of snow algae in ice cores could reveal the temporal variation in snow algae in the past, and also environmental conditions relating propagation of snow algae. In this study, we anlalyzed snow algae preserved in an ice core of Grigoriev Ice cap located in eastern Kyrgyzstan of the central Asia, and to describe their temporal variations for the last 200 years. The ice core drilling was carried out on September in 2007 on the Grigoriev Ice cap in the Kyrgyz Tien Shen Mountains. A 87 m long ice core from the surface to the bedrock was recovered at the top of the ice cap. The core was horizontally cut every 5 cm (total 1212 samples). The samples were melted and preserved as a 3% formalin solution. After the sample water was filtered through a hydrophilized PTFE membrane filter, observed by microscope. Snow algae in the sample water were counting. The algal biomass was represented by the cell number per unit water volume. Here, we showed the results between the surface to the 64 m in depth. We also analyzed the snow algal communities on the surface of the ice cap collected from five different sites from the top down to the terminus. Microscopy revealed that the ice core contained three taxa of filamentous cyanobacteria, an unicellular cyanobacterium, and two green algae. They were also found on the ice or snow surface of the i Ice cap. The quantitative analyses of the algae in the part of upper 64 m deep of the ice core samples revealed that the algal biomass varied significantly and showed many peaks. Furthermore, the biomass profile differed among the taxa. The filamentous cyanobacterium varied from 0.0 to 4.6 x 103?m3 mL-1 (mean: 56?m3 mL-1 ), the unicellular cyanobacterium varied from 0.0 to 3.0 x 104?m3 mL-1 (mean: 1.2 x 103?m3 mL-1 ), and Green algae varied from 0.0 to 2.3 x 104?m3 mL-1 (mean: 2.2 x 103?m3 mL-1 ). Based on the dating by pollen grains, the 64 m core covers 237 years. The results suggest that the snow algae did not grow every year on the top of the ice cap, and their biomass and community structure varied greatly from year to year. The total biomass after the 1960s was significantly higher than those before the 1950s. This suggested suggests that the surface conditions changed more favorable to the growth of algae in the 1960s. Annal variation of the algal biomass was found to be significantly correlated with air temperature at the nearest observing station from Grigoriev the iIce cap and hydrogen stable isotope (?D) in the ice core. The results suggest that the algal growth is more preferable in warmer year.

  7. 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

  8. Modeling the summertime evolution of sea-ice melt ponds rsted-DTU, Electromagnetic Systems, Technical University of Denmark, Lyngby, Denmark

    E-print Network

    Feltham, Daniel

    ] During winter, Arctic sea ice is covered by snow creating a highly uniform reflective layer, precipitation, and solar radiation [Derksen et al., 1996; Papakyriakou, 1999]. The snow cover melts more or less of several centimeters to more than a meter deep [Eicken, 1994]. [3] Laxon et al. [2003] used data from radar

  9. Hydrographic Preconditioning for Seasonal Sea Ice Anomalies in the Labrador Sea

    E-print Network

    Fenty, Ian

    This study investigates the hydrographic processes involved in setting the maximum wintertime sea ice (SI) extent in the Labrador Sea and Baffin Bay. The analysis is based on an ocean and sea ice state estimate covering ...

  10. Snow and Ice Climatology of the Western United States and Alaska from MODIS

    NASA Astrophysics Data System (ADS)

    Rittger, K. E.; Painter, T. H.; Mattmann, C. A.; Seidel, F. C.; Burgess, A.; Brodzik, M.

    2013-12-01

    The climate and hydroclimate of the Western US and Alaska are tightly coupled to their snow and ice cover. The Western US depends on mountain snowmelt for the majority of its water supply to agriculture, industrial and urban use, hydroelectric generation, and recreation, all driven by increasing population and demand. Alaskan snow and glacier cover modulate regional climate and, as with the Western US, dominate water supply and hydroelectric generation in much of the state. Projections of climate change in the Western US and Alaska suggest that the most pronounced impacts will include reductions of mountain snow and ice cover, earlier runoff, and a greater fraction of rain instead of snow. We establish a snow and ice climatology of the Western US and Alaska using physically based MODIS Snow Covered Area and Grain size model (MODSCAG) for fractional snow cover, the MODIS Dust Radiative Forcing in Snow model (MODDRFS) for radiative forcing by light absorbing impurities in snow, and the MODIS Permanent Ice model (MODICE) for annual minimum exposed snow. MODSCAG and MODDRFS use EOS MOD09GA historical reflectance data (2000-2012) to provide daily and 8-day composites and near real time products since the beginning of 2013, themselves ultimately composited to 8-day products. The compositing method considers sensor-viewing geometry, solar illumination, clouds, cloud shadows, aerosols and noisy detectors in order to select the best pixel for an 8-day period. The MODICE annual minimum exposed snow and ice product uses the daily time series of fractional snow and ice from MODSCAG to generate annual maps. With this project we have established an ongoing, national-scale, consistent and replicable approach to assessing current and projected climate impacts and climate-related risk in the context of other stressors. We analyze the products in the Northwest, Southwest, and Alaska/Arctic regions of the National Climate Assessment for the last decade, the nation's hottest on record. In the Northwest we use the observations to investigate earlier snowmelt, in the Southwest drought, and in Alaska to measure the change in glacier area. We compare the MODIS retrievals to a time series of AVIRIS retrievals at higher spatial resolution spanning 289km2 and 61km2 in the California's Sierra Nevada and Colorado's Senator Beck Basin. We continue to nest specific investigations of regions and topics that have high priority due to existing or anticipated climate stresses, generally in the context of a variety of other concerns.

  11. AMSR2 Daily Arctic Sea Ice - 2014 - Duration: 33 seconds.

    NASA Video Gallery

    In this animation, the daily Arctic sea ice and seasonal land cover change progress through time, from March 21, 2014 through the 3rd of August, 2014. Over the water, Arctic sea ice changes from da...

  12. Monitoring Snow and Land Ice Using Satellite data in the GMES Project CryoLand

    NASA Astrophysics Data System (ADS)

    Bippus, Gabriele; Nagler, Thomas

    2013-04-01

    The main objectives of the project "CryoLand - GMES Service Snow and Land Ice" are to develop, implement and validate services for snow, glaciers and lake and river ice products as a Downstream Service within the Global Monitoring for Environment and Security (GMES) program of the European Commission. CryoLand exploits Earth Observation data from current optical and microwave sensors and of the upcoming GMES Sentinel satellite family. The project prepares also the basis for the cryospheric component of the GMES Land Monitoring services. The CryoLand project team consists of 10 partner organisations from Austria, Finland, Norway, Sweden, Switzerland and Romania and is funded by the 7th Framework Program of the European Commission. The CryoLand baseline products for snow include fractional snow extent from optical satellite data, the extent of melting snow from SAR data, and coarse resolution snow water equivalent maps from passive microwave data. Experimental products include maps of snow surface wetness and temperature. The products range from large scale coverage at medium resolution to regional products with high resolution, in order to address a wide user community. Medium resolution optical data (e.g. MODIS, in the near future Sentinel-3) and SAR (ENVISAT ASAR, in the near future Sentinel-1) are the main sources of EO data for generating large scale products in near real time. For generation of regional products high resolution satellite data are used. Glacier products are based on high resolution optical (e.g. SPOT-5, in the near future Sentinel-2) and SAR (TerraSAR-X, in the near future Sentinel-1) data and include glacier outlines, mapping of glacier facies, glacier lakes and ice velocity. The glacier products are generated on users demand. Current test areas are located in the Alps, Norway, Greenland and the Himalayan Mountains. The lake and river ice products include ice extent and its temporal changes and snow extent on ice. The algorithms for these products are in development. One major task of CryoLand is the performance assessment of the products, which is carried out in different environments, climate zones and land cover types, selected jointly with users. Accuracy assessment is done for test areas using in-situ data and very high resolution satellite data. This presentation gives an overview on the processing lines and demonstration products for snow, glacier and lake ice parameters including examples of the product accuracy assessment. An important point of the CryoLand project is the use of advanced information technology, which is applied to process and distribute snow and land ice products in near real time.

  13. Studies of Antarctic Sea Ice Concentrations from Satellite Data and Their Applications

    NASA Technical Reports Server (NTRS)

    Comiso, Josefino C.; Steffen, Konrad; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    Large changes in the sea ice cover have been observed recently. Because of the relevance of such changes to climate change studies it is important that key ice concentration data sets used for evaluating such changes are interpreted properly. High and medium resolution visible and infrared satellite data are used in conjunction with passive microwave data to study the true characteristics of the Antarctic sea ice cover, assess errors in currently available ice concentration products, and evaluate the applications and limitations of the latter in polar process studies. Cloud-free high resolution data provide valuable information about the natural distribution, stage of formation, and composition of the ice cover that enables interpretation of the large spatial and temporal variability of the microwave emissivity of Antarctic sea ice. Comparative analyses of co-registered visible, infrared and microwave data were used to evaluate ice concentrations derived from standard ice algorithms (i.e., Bootstrap and Team) and investigate the 10 to 35% difference in derived values from large areas within the ice pack, especially in the Weddell Sea, Amundsen Sea, and Ross Sea regions. Landsat and OLS data show a predominance of thick consolidated ice in these areas and show good agreement with the Bootstrap Algorithm. While direct measurements were not possible, the lower values from the Team Algorithm results are likely due to layering within the ice and snow and/or surface flooding, which are known to affect the polarization ratio. In predominantly new ice regions, the derived ice concentration from passive microwave data is usually lower than the true percentage because the emissivity of new ice changes with age and thickness and is lower than that of thick ice. However, the product provides a more realistic characterization of the sea ice cover, and are more useful in polar process studies since it allows for the identification of areas of significant divergence and polynya activities. Also, heat and salinity fluxes are proportionately increased in these areas compared to those from the thicker ice areas. A slight positive trend in ice extent and area from 1978 through 2000 is observed consistent with slight continental cooling during the period. However, the confidence in this result is only moderate because the overlap period for key instruments is just one month and the sensitivity to changes in sensor characteristics, calibration and threshold for the ice edge is quite high.

  14. Fram Strait sea ice outflow

    NASA Technical Reports Server (NTRS)

    Kwok, R.; Cunningham, G. F.; Pang, S. S.

    2004-01-01

    We summarize 24 years (1978??2) of ice export estimates and examine, over a 9-year record, the associated variability in the time-varying upward-looking sonar (ULS) thickness distributions of the Fram Strait.

  15. Comparative Views of Arctic Sea Ice Growth

    NASA Technical Reports Server (NTRS)

    2000-01-01

    NASA researchers have new insights into the mysteries of Arctic sea ice, thanks to the unique abilities of Canada's Radarsat satellite. The Arctic is the smallest of the world's four oceans, but it may play a large role in helping scientists monitor Earth's climate shifts.

    Using Radarsat's special sensors to take images at night and to peer through clouds, NASA researchers can now see the complete ice cover of the Arctic. This allows tracking of any shifts and changes, in unprecedented detail, over the course of an entire winter. The radar-generated, high-resolution images are up to 100 times better than those taken by previous satellites.

    The two images above are separated by nine days (earlier image on the left). Both images represent an area (approximately 96 by 128 kilometers; 60 by 80 miles)located in the Baufort Sea, north of the Alaskan coast. The brighter features are older thicker ice and the darker areas show young, recently formed ice. Within the nine-day span, large and extensive cracks in the ice cover have formed due to ice movement. These cracks expose the open ocean to the cold, frigid atmosphere where sea ice grows rapidly and thickens.

    Using this new information, scientists at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., can generate comprehensive maps of Arctic sea ice thickness for the first time. 'Before we knew only the extent of the ice cover,' said Dr. Ronald Kwok, JPL principal investigator of a project called Sea Ice Thickness Derived From High Resolution Radar Imagery. 'We also knew that the sea ice extent had decreased over the last 20 years, but we knew very little about ice thickness.'

    'Since sea ice is very thin, about 3 meters (10 feet) or less,'Kwok explained, 'it is very sensitive to climate change.'

    Until now, observations of polar sea ice thickness have been available for specific areas, but not for the entire polar region.

    The new radar mapping technique has also given scientists a close look at how the sea ice cover grows and contorts over time. 'Using this new data set, we have the first estimates of how much ice has been produced and where it formed during the winter. We have never been able to do this before,' said Kwok. 'Through our radar maps of the Arctic Ocean, we can actually see ice breaking apart and thin ice growth in the new openings.'

    RADARSAT gives researchers a piece of the overall puzzle every three days by creating a complete image of the Arctic. NASA scientists then put those puzzle pieces together to create a time-lapsed view of this remote and inhospitable region. So far, they have processed one season's worth of images.

    'We can see large cracks in the ice cover, where most ice grows,' said Kwok. 'These cracks are much longer than previously thought, some as long as 2,000 kilometers (1,200 miles),' Kwok continued. 'If the ice is thinning due to warming, we'll expect to see more of these long cracks over the Arctic Ocean.'

    Scientists believe this is one of the most significant breakthroughs in the last two decades of ice research. 'We are now in a position to better understand the sea ice cover and the role of the Arctic Ocean in global climate change,' said Kwok.

    Radar can see through clouds and any kind of weather system, day or night, and as the Arctic regions are usually cloud-covered and subject to long, dark winters, radar is proving to be extremely useful. However, compiling these data into extremely detailed pictures of the Arctic is a challenging task.

    'This is truly a major innovation in terms of the quantities of data being processed and the novelty of the methods being used,' said Verne Kaupp, director of the Alaska SAR Facility at the University of Alaska, Fairbanks.

    The mission is a joint project between JPL, the Alaska SAR Facility, and the Canadian Space Agency. Launched by NASA in 1995, the Radarsat satellite is operated by the Canadian Space Agency. JPL manages the Sea Ice Thickness Derived From High Resolution Radar Imagery pro

  16. Multi-year Arctic Sea Ice - Duration: 43 seconds.

    NASA Video Gallery

    The most visible change in the Arctic region in recent years has been the rapid decline of the perennial ice cover. The perennial ice is the portion of the sea ice floating on the surface of the oc...

  17. A study of the surface temperature and the thickness of the Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Herman, R. B.; Zhao, B.; Blake, D.

    2010-12-01

    In March 2010, a study was performed to investigate a possible correlation between the surface temperature and the thickness of the Arctic sea ice just offshore from Barrow, Alaska. Temperature readings were acquired using Thermochron digital temperature data loggers at 1-meter intervals along a 500-meter line. Electrical resistivity data and snow depth readings were obtained concurrently along this line. In addition, resistivity data was obtained repeatedly along this line over the course of two weeks to investigate the time scale over which the meter-scale structure of the sea ice might change. A number of problems with the temperature measurements were encountered including having a limited number of Thermochrons, their measurement relaxation times, contamination by the ambient air temperature, and moving them along the survey line without contaminating the data by touching them. The Thermochron data will be compared with the resistivity and snow depth data. A possible model of heat transfer through the ice will be discussed. This model could allow the thickness of the sea ice to be determined from the temperature on the surface of the ice along with an assumption of the temperature of the water below the ice.

  18. Quaternary Sea-ice history in the Arctic Ocean based on a new Ostracode sea-ice proxy

    USGS Publications Warehouse

    Cronin, T. M.; Gemery, L.; Briggs, W.M.; Jakobsson, M.; Polyak, L.; Brouwers, E.M.

    2010-01-01

    Paleo-sea-ice history in the Arctic Ocean was reconstructed using the sea-ice dwelling ostracode Acetabulastoma arcticum from late Quaternary sediments from the Mendeleyev, Lomonosov, and Gakkel Ridges, the Morris Jesup Rise and the Yermak Plateau. Results suggest intermittently high levels of perennial sea ice in the central Arctic Ocean during Marine Isotope Stage (MIS) 3 (25-45 ka), minimal sea ice during the last deglacial (16-11 ka) and early Holocene thermal maximum (11-5 ka) and increasing sea ice during the mid-to-late Holocene (5-0 ka). Sediment core records from the Iceland and Rockall Plateaus show that perennial sea ice existed in these regions only during glacial intervals MIS 2, 4, and 6. These results show that sea ice exhibits complex temporal and spatial variability during different climatic regimes and that the development of modern perennial sea ice may be a relatively recent phenomenon. ?? 2010.

  19. 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 specific roles for particular users (or groups of users); this role-based access will be necessary to support a diverse user population while maintaining the integrity of the data and protecting personal information, or the location of sensitive sites, captured in the data records. Additionally, future improvements to the interface will include the ability to upload photos and videos to capture visual records of the environment. The SIZONet application was developed to provide a robust interface for working with observational data. The contributed nature of the data, however, presents a unique set of collaborative benefits and challenges as we work towards the final implementation of the application. The successful partnership supporting the observation network is a direct function of the long-term relationships established between university-based researchers and community members.

  20. Sensitivity of CryoSat-2 Arctic sea-ice volume trends on radar-waveform interpretation

    NASA Astrophysics Data System (ADS)

    Ricker, R.; Hendricks, S.; Helm, V.; Skourup, H.; Davidson, M.

    2014-04-01

    Several studies have shown that there is considerable evidence that the Arctic sea-ice is thinning during the last decades. When combined with the observed rapid reduction of ice-covered area this leads to a decline in sea-ice volume. The only remote sensing technique capable of quantifying this ice volume decrease at global scale is satellite altimetry. In this context the CryoSat-2 satellite was launched in 2010 and is equipped with the Ku-band SAR radar altimeter SIRAL, which we use to derive sea-ice freeboard defined as the height of the ice surface above the local sea level. In the context of quantifying Arctic ice-volume decrease at global scale, the CryoSat-2 satellite was launched in 2010 and is equipped with the Ku-band SAR radar altimeter SIRAL, which we use to derive sea-ice freeboard defined as the height of the ice surface above the sea level. Accurate CryoSat-2 range measurements over open water and the ice surface in the order of centimeters are necessary to achieve the required accuracy of the freeboard to thickness conversion. Besides uncertainties of the actual sea-surface height and limited knowledge of ice and snow properties, the penetration of the radar signal into the snow cover and therefore the interpretation of radar echoes is crucial. This has consequences in the selection of retracker algorithms which are used to track the main scattering horizon and assign a range estimate to each CryoSat measurement. In this paper we apply a retracker algorithm with thresholds of 40%, 50% and 80% of the first maximum of radar echo power, spanning the range of values used in current literature. For the 40% threshold we assume that the main scattering horizon lies at a certain depth between the surface and snow-ice interface as verified through coincident CryoSat-2 and airborne laser altimetry measurements. This contrasts with the 50% and 80% thresholds where we assume the ice-snow interface as the main scattering horizon similar to other published studies. Using the selected retrackers we evaluate the uncertainties of trends in sea-ice freeboard and higher level products that arise from the choice of the retracker threshold only, independently from the uncertainties related to snow and ice properties. Our study shows that the choice of retracker thresholds does have a non-negligible impact on magnitude estimates of sea-ice freeboard, thickness and volume, but that the main trends in these parameters are less affected. Specifically we find declines of Arctic sea-ice volume of 9.7% (40% threshold), 10.9% (50% threshold) and 6.9% (80% threshold) between March 2011 and March 2013. In contrast to that we find increases in Arctic sea-ice volume of 27.88% (40% threshold), 25.71% (50% threshold) and 32.65% (80% threshold) between November 2011 and November 2013. Furthermore we obtain a significant increase of freeboard from March 2013 to November 2013 in the area for multi-seasonal sea-ice north of Greenland and the Canadian Archipelago. Since this is unlikely it gives rise to the assumption that applying different retracker thresholds depending on seasonal properties of the snow load is necessary in the future.

  1. Weddell Sea exploration from ice station

    NASA Astrophysics Data System (ADS)

    Ice Station Weddell Group of Principal Investigators; Chief Scientists; Gordon, Arnold L.

    On January 18, 1915, the Endurance and Sir Ernest Shackleton and his crew were stranded in the ice of the Weddell Sea and began one of the most famous drifts in polar exploration. Shackleton turned a failure into a triumph by leading all of his team to safety [Shackleton, 1919]. The drift track of the Endurance and the ice floe occupied by her stranded crew after the ship was lost on November 21, 1915, at 68°38.5?S and 52°26.5?W, carried the group along the western rim of the Weddell Gyre, representing a rare human presence in this region of perennial sea-ice cover.Seventy-seven years later, in 1992, the first intentional scientific Southern Ocean ice drift station, Ice Station Weddell-1 (ISW-1), was established in the western Weddell Sea by a joint effort of the United States and Russia. ISW-1 followed the track of the Endurance closely (Figure 1) and gathered an impressive array of data in this largely unexplored corner of the Southern Ocean, the western edge of the Weddell Gyre.

  2. Ocean Atmosphere Sea Ice Soil User's Guide

    E-print Network

    Oscillation (ENSO) or the greenhouse gases global warming effect. The models can possibly run on variousOASIS 2.0 Ocean Atmosphere Sea Ice Soil User's Guide and Reference Manual November 1995 Laurent an efficient and easy­to­use tool for coupling independent general circulation models of the atmosphere

  3. Ocean Atmosphere Sea Ice Soil User's Guide

    E-print Network

    such as the natural variability, El Ni~no Southern Oscillation (ENSO) or the greenhouse gas global warming effectOASIS3 Ocean Atmosphere Sea Ice Soil User's Guide oasis3 prism 2­2, June 2004 Sophie Valcke 1 tool for coupling independent general circulation models of the atmosphere and the ocean (A/O­ GCMs

  4. Ocean Atmosphere Sea Ice Soil User's Guide

    E-print Network

    such as the natural variability, El Ni~no Southern Oscillation (ENSO) or the greenhouse gas global warming effectOASIS3 Ocean Atmosphere Sea Ice Soil User's Guide oasis3 prism 2­3, August 2004 Sophie Valcke 1 tool for coupling independent general circulation models of the atmosphere and the ocean (A/O­ GCMs

  5. Moving from Ship to Arctic Sea Ice

    USGS Multimedia Gallery

    Two U.S. Coast Guard members are being transported by crane from U.S. Coast Guard Cutter Healy onto a piece of multi-year Arctic sea ice. This was during a scientific expedition to map the Arctic seafloor. The expedition was a joint effort using two ships, the Healy and the Canadian Coast Guard Ship...

  6. Checking Stability of Arctic Sea Ice

    USGS Multimedia Gallery

    Two U.S. Coast Guard members are checking the stability of a piece of multi-year Arctic sea ice. They were lowered by crane from U.S. Coast Guard Cutter Healy. This was during a scientific expedition to map the Arctic seafloor. The expedition was a joint effort using two ships, Healy and the Canadia...

  7. Mathematics of Sea Ice K. M. Golden

    E-print Network

    Golden, Kenneth M.

    the food chain to the top predators ­ killer whales, leopard seals, and polar bears. The brine and 1990's. While global climate models generally predict de- clines in the polar sea ice packs over the 21 extensive algal and bacte- rial communities which are essential for support- ing life in the polar oceans

  8. An ice core record of net snow accumulation and seasonal snow chemistry at Mt. Waddington, southwest British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Neff, P. D.; Steig, E. J.; Clark, D. H.; McConnell, J. R.; Pettit, E. C.; Menounos, B.

    2011-12-01

    We recovered a 141 m ice 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 ice show unambiguous seasonal variations, allowing for annual dating of the core. Clustered melt layers, originating from summer surface heating, also aid in the dating of the core. Seasonality 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 ice 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 ice core, after correcting for ice 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 ice 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 ice with an age of several hundred to 1000 years.

  9. A Comparison of Sea Ice Surface Elevation, Freeboard and Thickness Estimates from Cryosat-2 and Operational IceBridge in High Latitude Areas of Arctic

    NASA Astrophysics Data System (ADS)

    Xia, W.; Xie, H.

    2013-12-01

    The European Space Agency Cryosat-2 mission has been providing high-spatial resolution cryosphere observations with space-borne synthetic aperture interferometric radar altimeter (SIRAL) since 2010. Sea ice elevation, freeboard and thickness estimation by Cryosat-2 SAR products are compared with the observations by airborne topographic mapper (ATM) and snow radar of the NASA Operational IceBridge (OIB) in Arctic. During the May 2011 around 70~88 degree North, the two dataset are well co-located (within 1 degree latitude/longitude) and contemporary (within one day) with each other, observing mainly multi-year ice during that winter. Results showed that: (1) Surface elevation (with respect to WGS 84 ellipsoid) measured by Cryosat-2 tend to observe a lower (around 0.5 to 1 meters) surface elevation as the SIRAL is a snow penetrating Ku-band radar, and the OIB airborne topographic mapper is an LiDAR; (2) Snow depth estimation by UCL-04 model associated with Cryosat-2 product tend to be higher (around 0.1~0.5 meters) than that measured by snow radar used during the OIB flights; (3) The mean sea surface high estimation from these two products tend to be slightly differ; (4) Ice thickness estimated with Cryosat-2 products tend to be higher than that of the OIB, due to higher snow density modeled by UCL-04.

  10. The refreezing of melt ponds on Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Flocco, Daniela; Feltham, Daniel L.; Bailey, Eleanor; Schroeder, David

    2015-02-01

    The presence of melt ponds on the surface of Arctic sea ice significantly reduces its albedo, inducing a positive feedback leading to sea ice thinning. While the role of melt ponds in enhancing the summer melt of sea ice is well known, their impact on suppressing winter freezing of sea ice has, hitherto, received less attention. Melt ponds freeze by forming an ice lid at the upper surface, which insulates them from the atmosphere and traps pond water between the underlying sea ice and the ice lid. The pond water is a store of latent heat, which is released during refreezing. Until a pond freezes completely, there can be minimal ice growth at the base of the underlying sea ice. In this work, we present a model of the refreezing of a melt pond that includes the heat and salt balances in the ice lid, trapped pond, and underlying sea ice. The model uses a two-stream radiation model to account for radiative scattering at phase boundaries. Simulations and related sensitivity studies suggest that trapped pond water may survive for over a month. We focus on the role that pond salinity has on delaying the refreezing process and retarding basal sea ice growth. We estimate that for a typical sea ice pond coverage in autumn, excluding the impact of trapped ponds in models overestimates ice growth by up to 265 million km3, an overestimate of 26%.

  11. Sea ice impacts on spring bloom dynamics and net primary production in the Eastern Bering Sea

    NASA Astrophysics Data System (ADS)

    Brown, Zachary W.; Arrigo, Kevin R.

    2013-01-01

    In the Eastern Bering Sea, changes in sea ice have been implicated in recent major upper-trophic level shifts. However, the underlying relationships between sea ice and primary producers have not been well tested. Here, we combine data from multiple satellite platforms, reanalysis model results and biophysical moorings to explore the dynamics of spring and summer primary production in relation to sea ice conditions. In the northern Bering Sea, sea ice consistently retreated in late spring, leading to ice-edge phytoplankton blooms in cold (0-1 °C) waters. However, in the southeastern Bering Sea, sea ice retreat was far more irregular. Although this did not significantly alter bloom timing, late retreat led to blooms at the ice-edge while early retreat led to blooms in open waters that were warmer (?5.4 °C) and >70% more productive. Early sea ice retreat also led to higher productivity in summer, likely due to weaker thermal stratification. Overall, annual net primary production during warm years of early sea ice retreat was enhanced by 40-50% compared to years with late sea ice retreat in the southeastern Bering Sea. These findings suggest the potential for future sea ice loss to enhance overall carrying capacity of the southeastern Bering Sea ecosystem. Consistently warm blooms in the future may also channel more energy flow toward the pelagic, rather than benthic, environment. To date, however, neither sea ice extent nor the timing of its retreat have undergone long-term changes in the Eastern Bering Sea.

  12. Microwave emission from snow and glacier ice. [brightness temperature for snow fields

    NASA Technical Reports Server (NTRS)

    Chang, T. C.; Gloersen, P.; Schmugge, T.; Wilheit, T. T.; Zwally, H. J.

    1975-01-01

    The microwave brightness temperature for snow fields was studied assuming that the snow cover consists of closely packed scattering spheres which do not interact coherently. The Mie scattering theory was used to compute the volume scattering albedo. It is shown that in the wavelength range from 0.8 to 2.8 cm, most of the micro-radiation emanates from a layer 10 meters or less in thickness. It is concluded that it is possible to determine snow accumulation rates as well as near-surface temperature.

  13. Improved identification of clouds and ice/snow covered surfaces in SCIAMACHY observations

    NASA Astrophysics Data System (ADS)

    Krijger, J. M.; Tol, P.; Istomina, L. G.; Schlundt, C.; Schrijver, H.; Aben, I.

    2011-10-01

    In the ultra-violet, visible and near infra-red wavelength range the presence of clouds can strongly affect the satellite-based passive remote sensing observation of constituents in the troposphere, because clouds effectively shield the lower part of the atmosphere. Therefore, cloud detection algorithms are of crucial importance in satellite remote sensing. However, the detection of clouds over snow/ice surfaces is particularly difficult in the visible wavelengths as both clouds an snow/ice are both white and highly reflective. The SCIAMACHY Polarisation Measurement Devices (PMD) Identification of Clouds and Ice/snow method (SPICI) uses the SCIAMACHY measurements in the wavelength range between 450 nm and 1.6 ?m to make a distinction between clouds and ice/snow covered surfaces, specifically developed to identify cloud-free SCIAMACHY observations. For this purpose the on-board SCIAMACHY PMDs are used because they provide higher spatial resolution compared to the main spectrometer measurements. In this paper we expand on the original SPICI algorithm (Krijger et al., 2005a) to also adequately detect clouds over snow-covered forests which is inherently difficult because of the similar spectral characteristics. Furthermore the SCIAMACHY measurements suffer from degradation with time. This must be corrected for adequate performance of SPICI over the full SCIAMACHY time range. Such a correction is described here. Finally the performance of the new SPICI algorithm is compared with various other datasets, such as from FRESCO, MICROS and AATSR, focusing on the algorithm improvements.

  14. Satellites - New global observing techniques for ice and snow

    NASA Technical Reports Server (NTRS)

    Gloersen, P.; Salomonson, V. V.

    1975-01-01

    The possibility that the variation in areal extent of the snow cover may be related by empirical means to the average monthly run-off in a given watershed was demonstrated by comparing run-off records from the Indus River Basin in south-east Asia with a series of snow-cover maps obtained from Nimbus-3 and 4 imagery. Similar studies using the higher spatial resolution available with ERTS-1 imagery were carried out for the Wind River Mountains watersheds in Wyoming, where it was found that the empirical relationship varied with mean elevation of the watershed. In addition, digital image enhancement techniques are shown to be useful for identifying glacier features thought to be related to extent of snow cover, moraine characteristics, debris coverage, and the like. Finally, longer wavelength observations using sensors on board the Nimbus-5 satellite are shown to be useful for indicating crystal size distributions and onset of melting on glacier snow cover.

  15. An Improved Cryosat-2 Sea Ice Freeboard Retrieval Algorithm Through the Use of Waveform Fitting

    NASA Technical Reports Server (NTRS)

    Kurtz, Nathan T.; Galin, N.; Studinger, M.

    2014-01-01

    We develop an empirical model capable of simulating the mean echo power cross product of CryoSat-2 SAR and SAR In mode waveforms over sea ice covered regions. The model simulations are used to show the importance of variations in the radar backscatter coefficient with incidence angle and surface roughness for the retrieval of surfaceelevation of both sea ice floes and leads. The numerical model is used to fit CryoSat-2 waveforms to enable retrieval of surface elevation through the use of look-up tables and a bounded trust region Newton least squares fitting approach. The use of a model to fit returns from sea ice regions offers advantages over currently used threshold retrackingmethods which are here shown to be sensitive to the combined effect of bandwidth limited range resolution and surface roughness variations. Laxon et al. (2013) have compared ice thickness results from CryoSat-2 and IceBridge, and found good agreement, however consistent assumptions about the snow depth and density of sea ice werenot used in the comparisons. To address this issue, we directly compare ice freeboard and thickness retrievals from the waveform fitting and threshold tracker methods of CryoSat-2 to Operation IceBridge data using a consistent set of parameterizations. For three IceBridge campaign periods from March 20112013, mean differences (CryoSat-2 IceBridge) of 0.144m and 1.351m are respectively found between the freeboard and thickness retrievals using a 50 sea ice floe threshold retracker, while mean differences of 0.019m and 0.182m are found when using the waveform fitting method. This suggests the waveform fitting technique is capable of better reconciling the seaice thickness data record from laser and radar altimetry data sets through the usage of consistent physical assumptions.

  16. Arctic Sea Ice: Trends, Stability and Variability

    NASA Astrophysics Data System (ADS)

    Moon, Woosok

    A stochastic Arctic sea-ice model is derived and analyzed in detail to interpret the recent decay and associated variability of Arctic sea-ice under changes in greenhouse gas forcing widely referred to as global warming. The approach begins from a deterministic model of the heat flux balance through the air/sea/ice system, which uses observed monthly-averaged heat fluxes to drive a time evolution of sea-ice thickness. This model reproduces the observed seasonal cycle of the ice cover and it is to this that stochastic noise---representing high frequency variability---is introduced. The model takes the form of a single periodic non-autonomous stochastic ordinary differential equation. Following an introductory chapter, the two that follow focus principally on the properties of the deterministic model in order to identify the main properties governing the stability of the ice cover. In chapter 2 the underlying time-dependent solutions to the deterministic model are analyzed for their stability. It is found that the response time-scale of the system to perturbations is dominated by the destabilizing sea-ice albedo feedback, which is operative in the summer, and the stabilizing long wave radiative cooling of the ice surface, which is operative in the winter. This basic competition is found throughout the thesis to define the governing dynamics of the system. In particular, as greenhouse gas forcing increases, the sea-ice albedo feedback becomes more effective at destabilizing the system. Thus, any projections of the future state of Arctic sea-ice will depend sensitively on the treatment of the ice-albedo feedback. This in turn implies that the treatment a fractional ice cover as the ice areal extent changes rapidly, must be handled with the utmost care. In chapter 3, the idea of a two-season model, with just winter and summer, is revisited. By breaking the seasonal cycle up in this manner one can simplify the interpretation of the basic dynamics. Whereas in the fully time-dependent seasonal model one finds stable seasonal ice cover (vanishing in the summer but reappearing in the winter), in previous two-season models such a state could not be found. In this chapter the sufficient conditions are found for a stable seasonal ice cover, which reside in including a time variation in the shortwave radiance during summer. This provides a qualitative interpretation of the continuous and reversible shift from perennial to seasonally-varying states in the more complex deterministic model. In order to put the stochastic model into a realistic observational framework, in chapter 4, the analysis of daily satellite retrievals of ice albedo and ice extent is described. Both the basic statistics are examined and a new method, called multi-fractal temporally weighted detrended fluctuation analysis, is applied. Because the basic data are taken on daily time scales, the full fidelity of the retrieved data is accessed and we find time scales from days and weeks to seasonal and decadal. Importantly, the data show a white-noise structure on annual to biannual time scales and this provides the basis for using a Wiener process for the noise in the stochastic Arctic sea-ice model. In chapter 5 a generalized perturbation analysis of a non-autonomous stochastic differential equation is developed and then applied to interpreting the variability of Arctic sea-ice as greenhouse gas forcing increases. The resulting analytic expressions of the statistical moments provide insight into the transient and memory-delay effects associated with the basic competition in the system: the ice-albedo feedback and long wave radiative stabilization along with the asymmetry in the nonlinearity of the deterministic contributions to the model and the magnitude and structure of the stochastic noise. A systematic study of the impact of the noise structure, from additive to multiplicative, is undertaken in chapters 6 and 7. Finally, in chapter 8 the matter of including a fractional ice cover into a deterministic model is addressed. It is found that a simple but crucial mistake

  17. 76 FR 7238 - Pipeline Safety: Dangers of Abnormal Snow and Ice Build-Up on Gas Distribution Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-09

    ...appear to have been related to either the stress of snow and ice or the malfunction of...appear to have been related to either the stress of snow and ice or malfunction of pressure...greatest risk. Damage may result from the stresses imposed by the additional loading of...

  18. Variability of Arctic Sea Ice as Determined from Satellite Observations

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.

    1999-01-01

    The compiled, quality-controlled satellite multichannel passive-microwave record of polar sea ice now spans over 18 years, from November 1978 through December 1996, and is revealing considerable information about the Arctic sea ice cover and its variability. The information includes data on ice concentrations (percent areal coverages of ice), ice extents, ice melt, ice velocities, the seasonal cycle of the ice, the interannual variability of the ice, the frequency of ice coverage, and the length of the sea ice season. The data reveal marked regional and interannual variabilities, as well as some statistically significant trends. For the north polar ice cover as a whole, maximum ice extents varied over a range of 14,700,000 - 15,900,000 sq km, while individual regions experienced much greater percent variations, for instance, with the Greenland Sea having a range of 740,000 - 1,110,000 sq km in its yearly maximum ice coverage. In spite of the large variations from year to year and region to region, overall the Arctic ice extents showed a statistically significant, 2.80% / decade negative trend over the 18.2-year period. Ice season lengths, which vary from only a few weeks near the ice margins to the full year in the large region of perennial ice coverage, also experienced interannual variability, along with spatially coherent overall trends. Linear least squares trends show the sea ice season to have lengthened in much of the Bering Sea, Baffin Bay, the Davis Strait, and the Labrador Sea, but to have shortened over a much larger area, including the Sea of Okhotsk, the Greenland Sea, the Barents Sea, and the southeastern Arctic.

  19. Holocene cooling culminates in sea ice oscillations in Fram Strait

    NASA Astrophysics Data System (ADS)

    Müller, Juliane; Werner, Kirstin; Stein, Ruediger; Fahl, Kirsten; Moros, Matthias; Jansen, Eystein

    2012-07-01

    A reconstruction of Holocene sea ice conditions in the Fram Strait provides insight into the palaeoenvironmental and palaeoceanographic development of this climate sensitive area during the past 8500 years BP. Organic geochemical analyses of sediment cores from eastern and western Fram Strait enable the identification of variations in the ice coverage that can be linked to changes in the oceanic (and atmospheric) circulation system. By means of the sea ice proxy IP25, phytoplankton-derived biomarkers and ice rafted detritus (IRD) increasing sea ice occurrences are traced along the western continental margin of Spitsbergen throughout the Holocene, which supports previous palaeoenvironmental reconstructions that document a general cooling. A further significant ice advance during the Neoglacial is accompanied by distinct sea ice fluctuations, which point to short-term perturbations in either the Atlantic Water advection or Arctic Water outflow at this site. At the continental shelf of East Greenland, the general Holocene cooling, however, seems to be less pronounced and sea ice conditions remained rather stable. Here, a major Neoglacial increase in sea ice coverage did not occur before 1000 years BP. Phytoplankton-IP25 indices ("PIP25-Index") are used for more explicit sea ice estimates and display a Mid Holocene shift from a minor sea ice coverage to stable ice margin conditions in eastern Fram Strait, while the inner East Greenland shelf experienced less severe to marginal sea ice occurrences throughout the entire Holocene.

  20. Towards an Ice-free Northern Sea Route?

    NASA Astrophysics Data System (ADS)

    Rodrigues, J. M.

    2006-12-01

    The reduction in sea ice extent and area that has taken place during the past few decades in the Russian Arctic, more rapid than anywhere else in the Northern Hemisphere, is one of the most striking environmental changes that have occurred on our planet. Using sea ice concentration data obtained from satellite passive microwave imagery we determine the monthly averaged position of the sea ice edge, the values of the sea ice extent and area for the White, Barents, Kara, Laptev, East Siberian, Chukchi and Bering Seas, and investigate how they have changed between 1979 and 2006. The rate of change in sea ice extent and area are almost always negative, null or approximately null. Very large reductions in ice extent occurred in the White Sea in June, July and October, in the Barents Sea in July, in the Laptev Sea in August, in the East Siberian Sea in September, and in the Chukchi Sea in September and October. Exceptions were the Barents Sea in September and the Bering Sea in December, January, February and June, where a significant increase in ice extent was observed. From the daily sea ice concentrations obtained from SSM/I devices on board NASA satellites, we derive the length of the ice-free season in specific points, mostly along the Northern Sea Route, and find how this quantity has evolved throughout the 1979-2006 period. We found that there was a considerable increase in the length of the ice-free season almost everywhere in the Russian Arctic. In the White, East Siberian and Chukchi Seas there are remarkable differences between the current figures and those of the late 1970s. A reduction was observed in some parts of the Bering Sea. This apparently long term decline in the amount of sea ice in the Russian Arctic opens new opportunities for the Northern Sea Route, which in the coming decades may become a real alternative to more conventional routes that connect the Atlantic and the Pacific.

  1. Ice core evidence for a 20th century decline of sea ice in the Bellingshausen Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Abram, Nerilie J.; Thomas, Elizabeth R.; McConnell, Joseph R.; Mulvaney, Robert; Bracegirdle, Thomas J.; Sime, Louise C.; Aristarain, Alberto J.

    2010-12-01

    This study uses ice core methanesulphonic acid (MSA) records from the Antarctic Peninsula, where temperatures have been warming faster than anywhere else in the Southern Hemisphere, to reconstruct the 20th century history of sea ice change in the adjacent Bellingshausen Sea. Using satellite-derived sea ice and meteorological data, we show that ice core MSA records from this region are a reliable proxy for regional sea ice change, with years of increased winter sea ice extent recorded by increased ice core MSA concentrations. Our reconstruction suggests that the satellite-observed sea ice decline in the Bellingshausen Sea during recent decades is part of a long-term regional trend that has occurred throughout the 20th century. The long-term perspective on sea ice in the Bellingshausen Sea is consistent with evidence of 20th century warming on the Antarctic Peninsula and may reflect a progressive deepening of the Amundsen Sea Low due to increasing greenhouse gas concentrations and, more recently, stratospheric ozone depletion. As a first-order estimate, our MSA-based reconstruction suggests that sea ice in the Bellingshausen Sea has retreated southward by ˜0.7° during the 20th century. Comparison with other 20th century sea ice observations, reconstructions, and model simulations provides a coherent picture of Antarctic sea ice decline during the 20th century, although with regional-scale differences evident in the timing and magnitude of this sea ice decline. This longer-term perspective contrasts with the small overall increase in Antarctic sea ice that is observed in post-1979 satellite data.

  2. Arctic Sea Ice Freeboard from Icebridge Acquisitions in 2009: Estimates and Comparisons with ICEsat

    NASA Technical Reports Server (NTRS)

    Kwok, R.; Cunningham, Glenn F.; Manizade, S. S.; Krabill, W. B.

    2012-01-01

    During the spring of 2009, the Airborne Topographic Mapper (ATM) system on the IceBridge mission acquired cross-basin surveys of surface elevations of Arctic sea ice. In this paper, the total freeboard derived from four 2000 km transects are examined and compared with those from the 2009 ICESat campaign. Total freeboard, the sum of the snow and ice freeboards, is the elevation of the air-snow interface above the local sea surface. Prior to freeboard retrieval, signal dependent range biases are corrected. With data from a near co-incident outbound and return track on 21 April, we show that our estimates of the freeboard are repeatable to within 4 cm but dependent locally on the density and quality of sea surface references. Overall difference between the ATM and ICESat freeboards for the four transects is 0.7 (8.5) cm (quantity in bracket is standard deviation), with a correlation of 0.78 between the data sets of one hundred seventy-eight 50 km averages. This establishes a level of confidence in the use of ATM freeboards to provide regional samplings that are consistent with ICESat. In early April, mean freeboards are 41 cm and 55 cm over first year and multiyear sea ice (MYI), respectively. Regionally, the lowest mean ice freeboard (28 cm) is seen on 5 April where the flight track sampled the large expanse of seasonal ice in the western Arctic. The highest mean freeboard (71 cm) is seen in the multiyear ice just west of Ellesmere Island from 21 April. The relatively large unmodeled variability of the residual sea surface resolved by ATM elevations is discussed.

  3. From the Sun to the Ice - Then Where? A Bi-polar, Integrated View of the Role of Polar Snow and Floating Ice Covers in the Earth's Heat Budget During IPY 2007/08

    NASA Astrophysics Data System (ADS)

    Eicken, H.; Grenfell, T.; Jeffries, M.; Perovich, D.; Sturm, M.

    2003-12-01

    The polar regions play a key role in the disposition of energy and in particular solar radiation in the earth's climate system. With the largest seasonal variations in surface albedo occurring over the polar oceans and with substantial changes in the extent and nature of the snow and ice covers in recent decades, the polar regions are a critical link between top-of-the atmosphere radiative fluxes and solar energy absorbed by the earth system. While recent studies have greatly improved our knowledge of the heat budget of the polar oceans, we are still far from understanding a number of fundamental questions related to the role of snow and ice in the global radiation budget and their importance for albedo feedback processes. For example, currently albedo parameterizations in large-scale sea ice and climate models are only partially successful in taking into account the physical processes driving seasonal and interannual albedo changes. In fact, the majority of models employ different albedo parameterizations for northern and southern hemisphere snow and sea ice. This is dictated by the strong contrasts in snow and ice melt processes in Arctic and Antarctic, which in of themselves are not all that well understood. Our own research in the Western Arctic and in the southern Ross Sea indicates that snow may play a crucial, currently underestimated role in governing these processes and hence the nature and magnitude of ice-albedo feedback processes. Here, we propose that an integrated, bi-polar examination of the interaction between snow and floating ice covers (sea and lake ice), coupled with a global-scale analysis of the role of polar ice masses in affecting the earth's radiation budget would provide an interesting and scientifically significant cryospheric thread within the framework of the IPY 2007/08. This work would also address other important aspects such as large-scale cloud radiative forcing over ice surfaces and spatio-temporal partitioning of the radiation reaching the surface. At the same time, such a program would provide direct linkages to the aims of the International Heliospheric Year. The observational effort would comprise a pan-polar approach to ground-based measurements along with satellite remote sensing, augmented by numerical simulations. Based on studies of the energy and mass balance of Arctic and Antarctic snow and ice covers, we will show how such a cryospheric component could be integrated into the overall aims of the IPY. IPY will provide an extraordinary opportunity to capture the imagination of the general public and school children. Our proposed effort will take advantage of this opportunity to convey information about the solar radiation and about the role the polar regions play in global climate. There will be an extensive educational outreach component that will include media contacts, web sites, classroom programs, and public lectures. Examples of such approaches, e.g., the Alaska Lake Ice and Snow Observatory Network (ALISON, www.gi.alaska.edu/alison) or Barrow Coastal Ice Observations (www.arcticice.org) will be discussed.

  4. Antarctic Sea Ice Variability and Trends, 1979-2010

    NASA Technical Reports Server (NTRS)

    Parkinson, C. L.; Cavalieri, D. J.

    2012-01-01

    In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978 - December 2010 reveal an overall positive trend in ice extents of 17,100 +/- 2,300 square km/yr. Much of the increase, at 13,700 +/- 1,500 square km/yr, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has, like the Arctic, instead experienced significant sea ice decreases, with an overall ice extent trend of -8,200 +/- 1,200 square km/yr. When examined through the annual cycle over the 32-year period 1979-2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9,100 +/- 6,300 square km/yr in February to a high of 24,700 +/- 10,000 square km/yr in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and Western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but differences in the magnitudes of the two trends identify regions with overall increasing ice concentrations and others with overall decreasing ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

  5. Investigating the Thermophysical Properties of the Ice-Snow Interface Under a Controlled Temperature Gradient

    NASA Astrophysics Data System (ADS)

    Hammonds, Kevin; Lieb-Lappen, Ross; Baker, Ian; Wang, Xuan; Courville, Zoe

    2015-04-01

    Of critical importance for avalanche forecasting, is the ability to draw meaningful conclusions from a handful of field observations. To this end, it is common for avalanche forecasters to not only have to rely on these sparse data, but also to use their own intuitive understanding of how these observations are correlated with the complex physical processes that produce mechanical instabilities within a snowpack. One such example of this is the long-held notion that kinetic snow metamorphism does not occur at bulk temperature gradients of less than -10°C/m. Although this may be true for the homogeneous case, it has become a point of contention as to whether or not this guideline should be applied to the more representative case of a heavily stratified and anisotropic snowpack. As an idealized case for our initial laboratory investigations, we have studied how an artificially created ice layer or "lens" would affect the thermophysical state of the snow layers adjacent to the ice lens and the ice lens itself, while being held under a controlled temperature gradient. Our findings have shown, via in-situ micro-thermocouple measurements, that a super-temperature gradient many times greater than the imposed bulk temperature gradient can exist within a millimeter above and below the surface of the ice lens. Furthermore, microstructural analysis via time-lapse X-ray Micro-Computed Tomography and environmental SEM imaging has been performed. Results from this analysis show new ice crystal growth and kinetic snow metamorphism occurring simultaneously on or near the ice lens itself with the connectivity density at the ice-snow interface increasing markedly more below the ice lens than above.

  6. Sea Ice Microorganisms: Environmental Constraints and Extracellular Responses

    PubMed Central

    Ewert, Marcela; Deming, Jody W.

    2013-01-01

    Inherent to sea ice, like other high latitude environments, is the strong seasonality driven by changes in insolation throughout the year. Sea-ice organisms are exposed to shifting, sometimes limiting, conditions of temperature and salinity. An array of adaptations to survive these and other challenges has been acquired by those organisms that inhabit the ice. One key adaptive response is the production of extracellular polymeric substances (EPS), which play multiple roles in the entrapment, retention and survival of microorganisms in sea ice. In this concept paper we consider two main areas of sea-ice microbiology: the physico-chemical properties that define sea ice as a microbial habitat, imparting particular advantages and limits; and extracellular responses elicited in microbial inhabitants as they exploit or survive these conditions. Emphasis is placed on protective strategies used in the face of fluctuating and extreme environmental conditions in sea ice. Gaps in knowledge and testable hypotheses are identified for future research. PMID:24832800

  7. Ice-sheet contributions to future sea-level change

    E-print Network

    Huybrechts, Philippe

    for correspondence (phuybrec@vub.ac.be). 1709 q 2006 The Royal Society #12;ice caps will probably be of greater which is lost. Hence, the contribution to sea level from glaciers and ice caps will diminish, whileIce-sheet contributions to future sea-level change BY J. M. GREGORY 1,2 AND P. HUYBRECHTS 3,4,* 1

  8. The application of ERTS imagery to monitoring Arctic sea ice. [mapping ice in Bering Sea, Beaufort Sea, Canadian Archipelago, and Greenland Sea

    NASA Technical Reports Server (NTRS)

    Barnes, J. C. (principal investigator); Bowley, C. J.

    1974-01-01

    The author has identified the following significant results. Because of the effect of sea ice on the heat balance of the Arctic and because of the expanding economic interest in arctic oil and minerals, extensive monitoring and further study of sea ice is required. The application of ERTS data for mapping ice is evaluated for several arctic areas, including the Bering Sea, the eastern Beaufort Sea, parts of the Canadian Archipelago, and the Greenland Sea. Interpretive techniques are discussed, and the scales and types of ice features that can be detected are described. For the Bering Sea, a sample of ERTS-1 imagery is compared with visual ice reports and aerial photography from the NASA CV-990 aircraft. The results of the investigation demonstrate that ERTS-1 imagery has substantial practical application for monitoring arctic sea ice. Ice features as small as 80-100 m in width can be detected, and the combined use of the visible and near-IR imagery is a powerful tool for identifying ice types. Sequential ERTS-1 observations at high latitudes enable ice deformations and movements to be mapped. Ice conditions in the Bering Sea during early March depicted in ERTS-1 images are in close agreement with aerial ice observations and photographs.

  9. Combined Satellite - and ULS-Derived Sea-Ice Flux in the Weddell Sea

    NASA Technical Reports Server (NTRS)

    Drinkwater, M.; Liu, X.; Harms, S.

    2000-01-01

    Several years of daily microwave satellite ice-drift are combined with moored Upward Looking Sonar (ULS) ice-drafts into an ice volume flux record at points along a flux gate across the Weddell Sea, Antarctica.

  10. Modeling brine and nutrient dynamics in Antarctic sea ice: the case of dissolved silica

    NASA Astrophysics Data System (ADS)

    Vancoppenolle, M.; Goosse, H.; de Montety, A.; Fichefet, T.; Tremblay, B.; Tison, J.

    2009-12-01

    Sea ice ecosystems are characterized by micro-algae living in brine inclusions. The growth rate of ice algae depends on light and nutrient supply. Here, the interactions between nutrients and brine dynamics under the influence of algae are investigated using a one-dimensional model. The model includes snow and ice thermodynamics with brine physics and an idealized sea ice biological component, characterized by one nutrient, namely dissolved silica (DSi). In the model, DSi follows brine motion and is consumed by ice algae. Depending on physical ice characteristics, the brine flow is either advective, diffusive or turbulent. The vertical profiles of ice salinity and DSi concentration are solutions of advection-diffusion equations. The model is configured to simulate the typical thermodynamic regimes of first-year Antarctic pack ice. The simulated vertical profiles of salinity and DSi qualitatively reproduce observations. Analysis of results highlights the role of convection in the lowermost 5-10 cm of ice. Convection mixes saline, nutrient-poor brine with comparatively fresh, nutrient-rich seawater. This implies a rejection of salt to the ocean and a flux of DSi to the ice. In presence of growing algae, the simulated ocean-to-ice DSi flux increases by 0-115% compared to an abiotic situation. In turn, primary production and brine convection act in synergy to form a nutrient pump. The other important processes are the flooding of the surface by seawater and the percolation of meltwater. The former refills nutrients near the ice surface in spring. The latter, if present, tends to expell nutrients from the ice in summer. Sketch of salt (left) and nutrient (right) exchanges at the ice-ocean interface proposed in this paper.

  11. Theory of the Sea Ice Thickness Distribution

    NASA Astrophysics Data System (ADS)

    Toppaladoddi, Srikanth; Wettlaufer, J. S.

    2015-10-01

    We use concepts from statistical physics to transform the original evolution equation for the sea ice thickness distribution g (h ) from Thorndike et al. into a Fokker-Planck-like conservation law. The steady solution is g (h )=N (q )hqe-h /H, where q and H are expressible in terms of moments over the transition probabilities between thickness categories. The solution exhibits the functional form used in observational fits and shows that for h ?1 , g (h ) is controlled by both thermodynamics and mechanics, whereas for h ?1 only mechanics controls g (h ). Finally, we derive the underlying Langevin equation governing the dynamics of the ice thickness h , from which we predict the observed g (h ). The genericity of our approach provides a framework for studying the geophysical-scale structure of the ice pack using methods of broad relevance in statistical mechanics.

  12. Monthly average polar sea-ice concentration

    USGS Publications Warehouse

    Schweitzer, Peter N.

    1995-01-01

    The data contained in this CD-ROM depict monthly averages of sea-ice concentration in the modern polar oceans. These averages were derived from the Scanning Multichannel Microwave Radiometer (SMMR) and Special Sensor Microwave/Imager (SSM/I) instruments aboard satellites of the U.S. Air Force Defense Meteorological Satellite Program from 1978 through 1992. The data are provided as 8-bit images using the Hierarchical Data Format (HDF) developed by the National Center for Supercomputing Applications.

  13. Cloud Detection over Snow and Ice Using MISR Data , Eugene E. Clothiaux

    E-print Network

    Yu, Bin

    Cloud Detection over Snow and Ice Using MISR Data Tao Shi , Bin Yu , Eugene E. Clothiaux , and Amy J. Braverman Abstract Clouds play a major role in Earth's climate and cloud detection prediction and global climate model studies. To advance the observational capabilities of detecting clouds

  14. Encyclopedia of Earth Sciences Series ENCYCLOPEDIA OF SNOW, ICE AND GLACIERS

    E-print Network

    Vuille, Mathias

    #12;Encyclopedia of Earth Sciences Series ENCYCLOPEDIA OF SNOW, ICE AND GLACIERS Volume Editors Professor of Biological and Agricultural Engineering, and Civil and Environmental Engineering at Texas A & M Sciences University of Bristol University Road Bristol BS8 1SS UK Aims of the Series The Encyclopedia

  15. User requirements for the snow and land ice services - CryoLand

    NASA Astrophysics Data System (ADS)

    Malnes, E.; Buanes, A.; Nagler, T.; Bippus, G.; Gustafsson, D.; Schiller, C.; Metsämäki, S.; Pulliainen, J.; Luojus, K.; Larsen, H. E.; Solberg, R.; Diamandi, A.; Wiesmann, A.

    2015-06-01

    CryoLand (2011-2015) is a project carried out within the 7th Framework of the European Commission aimed at developing downstream services for monitoring seasonal snow, glaciers and lake/river ice primarily based on satellite remote sensing. The services target private and public users from a wide variety of application areas, and aim to develop sustainable services after the project is completed. The project has performed a thorough user requirement survey in order to derive targeted requirements for the service and provide recommendations for the design and priorities of the service. In this paper we describe the methods used, the major findings in this user survey, and how we used the results to design and specify the CryoLand snow and land ice service. The user requirement analysis shows that a European operational snow and land ice service is required and that there exists developed cryosphere products that can meet the specific needs. The majority of the users were mainly interested not only in the snow services, but also the lake/river ice products and the glacier products were desired.

  16. Ice formation and growth shape bacterial community structure in Baltic Sea drift ice.

    PubMed

    Eronen-Rasimus, Eeva; Lyra, Christina; Rintala, Janne-Markus; Jürgens, Klaus; Ikonen, Vilma; Kaartokallio, Hermanni

    2015-02-01

    Drift ice, open water and under-ice water bacterial communities covering several developmental stages from open water to thick ice were studied in the northern Baltic Sea. The bacterial communities were assessed with 16S rRNA gene terminal-restriction fragment length polymorphism and cloning, together with bacterial abundance and production measurements. In the early stages, open water and pancake ice were dominated by Alphaproteobacteria and Actinobacteria, which are common bacterial groups in Baltic Sea wintertime surface waters. The pancake ice bacterial communities were similar to the open-water communities, suggesting that the parent water determines the sea-ice bacterial community in the early stages of sea-ice formation. In consolidated young and thick ice, the bacterial communities were significantly different from water bacterial communities as well as from each other, indicating community development in Baltic Sea drift ice along with ice-type changes. The thick ice was dominated by typical sea-ice genera from classes Flavobacteria and Gammaproteobacteria, similar to those in polar sea-ice bacterial communities. Since the thick ice bacterial community was remarkably different from that of the parent seawater, results indicate that thick ice bacterial communities were recruited from the rarer members of the seawater bacterial community. PMID:25764550

  17. Sea ice trends and cyclone activity in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Coggins, Jack; McDonald, Adrian; Rack, Wolfgang; Dale, Ethan

    2015-04-01

    Significant trends in the extent of Southern Hemisphere sea ice have been noted over the course of the satellite record, with highly variable trends between different seasons and regions. In this presentation, we describe efforts to assess the impact of cyclones on these trends. Employing a maximum cross-correlation method, we derive Southern Ocean ice-motion vectors from daily gridded SSMI 85.5 GHz brightness temperatures. We then derive a sea ice budget from the NASA-Team 25 km square daily sea ice concentrations. The budget quantifies the total daily change in sea ice area, and includes terms representing the effects of ice advection and divergence. A residual term represents the processes of rafting, ridging, freezing and thawing. We employ a cyclone tracking algorithm developed at the University of Canterbury to determine the timing, location, size and strength of Southern Hemisphere cyclones from mean sea-level pressure fields of the ERA-Interim reanalysis. We then form composites of the of sea ice budget below the location of cyclones. Unsurprisingly, we find that clockwise atmospheric flow around Southern Hemisphere cyclones exerts a strong influence on the movement of sea ice, an effect which is visible in the advection and divergence terms. Further, we assess the climatological importance of cyclones by comparing seasons of sea ice advance for periods with varying numbers of cyclones. This analysis is performed independently for each sea ice concentration pixel, thus affording us insight into the geographical importance of storm systems. We find that Southern Hemisphere sea ice extent is highly sensitive to the presence of cyclones in the periphery of the pack in the advance season. Notably, the sensitivity is particularly high in the northern Ross Sea, an area with a marked positive trend in sea ice extent. We discuss whether trends in cyclone activity in the Southern Ocean may have contributed to sea ice extent trends in this region.

  18. Commercial & Residential Property Maintenance Snow & Ice Control Members of

    E-print Network

    Isaacs, Rufus

    -2013 snow seasons. For Us, Business is Personal Your Way is a family owned and operated business. From business is personal. #12; a family approach to our business, we feel that our services will reflect a sense of family pride. For us

  19. Sea ice-atmospheric interaction: Application of multispectral satellite data in polar surface energy flux estimates

    NASA Technical Reports Server (NTRS)

    Steffen, Konrad; Key, J.; Maslanik, J.; Schweiger, A.

    1993-01-01

    This is the third annual report on: Sea Ice-Atmosphere Interaction - Application of Multispectral Satellite Data in Polar Surface Energy Flux Estimates. The main emphasis during the past year was on: radiative flux estimates from satellite data; intercomparison of satellite and ground-based cloud amounts; radiative cloud forcing; calibration of the Advanced Very High Resolution Radiometer (AVHRR) visible channels and comparison of two satellite derived albedo data sets; and on flux modeling for leads. Major topics covered are arctic clouds and radiation; snow and ice albedo, and leads and modeling.

  20. Modal Behavior of Hemispheric Sea Ice Covers

    NASA Technical Reports Server (NTRS)

    Gloersen, Per; Huang, Norden; Shen, Zheng

    1998-01-01

    Recent papers have described 18-year trends and annual oscillations in the Arctic and Antarctic sea ice extents, areas, and enclosed open water areas based on a newly-formulated 18.2-year ice concentration time series. This time series includes data for the entire Arctic and Antarctic ice covers, as well as for previously defined subregions consisting of 5 sectors in the Antarctic and 9 regions in the Arctic. It was obtained by fine-tuning the sea ice algorithm tie points individually for each of the four sensors used to acquire the data. In this paper, we extend these analyses to an examination of the intrinsic modes of these time series, obtained by means of Empirical Mode Decomposition, with emphasis on periodicities greater than the annual cycle. Quasibiennial and quasiquadrennial oscillations observed with a different technique and reported earlier for the first 8.8 years of this time series were also observed in the present series. However, the intrinsic modes were not monochromatic; they feature frequency as well as amplitude modulation within their respective frequency bands. Modal periods of up to 18 years are observed, with important implications for the trend analyses published earlier. These results are compared with the oscillations in the Length-of-Day and North Atlantic Oscillation parameters similarly determined for the same 18.2-year period.

  1. Tundra burning in 2007 - Did sea ice retreat matter?

    NASA Astrophysics Data System (ADS)

    Alexeev, Vladimir A.; Euskirchen, Eugénie S.; Cherry, Jessica E.; Busey, Robert C.

    2015-06-01

    The goal of this study was to assess the importance of the 2007 sea ice retreat for hydrologic conditions on the Alaskan North Slope, and how this may have influenced the outbreak of tundra fires in this region. This study concentrates on two years, 2007 and 1996, with different arctic sea ice conditions and tundra fire activity. The year of 2007 is characterized by a low summer sea ice extent (second lowest) and high tundra fire activity, while 1996 had high sea ice extent, and few tundra fires. Atmospheric lateral boundary forcing from the NCEP/NCAR Reanalysis drove the Weather Research and Forecast (WRF) model, along with varying sea ice surface forcing designed to delineate the role of sea ice. WRF runs successfully reproduced the differences between 1996 and 2007. Surprisingly, replacing sea ice conditions in 1996 run by those from 2007 and vice versa (2007 run with 1996 sea ice) did not change the overall picture. The atmospheric circulation in August of 1996 included a significant low-pressure system over the Beaufort and Chukchi Seas. However, in 2007, a high-pressure system dominated the circulation over the Beaufort Sea. It is argued that this difference in large-scale patterns, rather than retreat of sea ice, was responsible for anomalously dry and warm atmospheric conditions over the North Slope in summer and autumn 2007, suitable for high tundra fire activity. Circulation in 2012 is contrasted with that in 2007 to further stress its importance for local weather on the North Slope.

  2. Improving Arctic sea ice edge forecasts by assimilating high horizontal resolution sea ice concentration data into the US Navy's ice forecast systems

    NASA Astrophysics Data System (ADS)

    Posey, P. G.; Metzger, E. J.; Wallcraft, A. J.; Hebert, D. A.; Allard, R. A.; Smedstad, O. M.; Phelps, M. W.; Fetterer, F.; Stewart, J. S.; Meier, W. N.; Helfrich, S. R.

    2015-08-01

    This study presents the improvement in ice edge error within the US Navy's operational sea ice forecast systems gained by assimilating high horizontal resolution satellite-derived ice concentration products. Since the late 1980's, the ice forecast systems have assimilated near real-time sea ice concentration derived from the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager (SSMI and then SSMIS). The resolution of the satellite-derived product was approximately the same as the previous operational ice forecast system (25 km). As the sea ice forecast model resolution increased over time, the need for higher horizontal resolution observational data grew. In 2013, a new Navy sea ice forecast system (Arctic Cap Nowcast/Forecast System - ACNFS) went into operations with a horizontal resolution of ~ 3.5 km at the North Pole. A method of blending ice concentration observations from the Advanced Microwave Scanning Radiometer (AMSR2) along with a sea ice mask produced by the National Ice Center (NIC) has been developed, resulting in an ice concentration product with very high spatial resolution. In this study, ACNFS was initialized with this newly developed high resolution blended ice concentration product. The daily ice edge locations from model hindcast simulations were compared against independent observed ice edge locations. ACNFS initialized using the high resolution blended ice concentration data product decreased predicted ice edge location error compared to the operational system that only assimilated SSMIS data. A second evaluation assimilating the new blended sea ice concentration product into the pre-operational Navy Global Ocean Forecast System 3.1 also showed a substantial improvement in ice edge location over a system using the SSMIS sea ice concentration product alone. This paper describes the technique used to create the blended sea ice concentration product and the significant improvements in ice edge forecasting in both of the Navy's sea ice forecasting systems.

  3. Classification of Baltic Sea ice types by airborne multifrequency microwave radiometer

    SciTech Connect

    Kurvonen, L.; Hallikainen, M.

    1996-11-01

    An airborne multifrequency radiometer (24, 34, 48, and 94 GHz, vertical polarization) was used to investigate the behavior of the brightness temperature of different sea ice types in the Gulf of Bothnia (Baltic Sea). The measurements and the main results of the analysis are presented. The measurements were made in dry and wet conditions (air temperature above and below 0 C). The angle of incidence was 45{degree} in all measurements. The following topics are evaluated: (a) frequency dependency of the brightness temperature of different ice types, (b) the capability of the multifrequency radiometer to classify ice types for winter navigation purposes, and (c) the optimum measurement frequencies for mapping sea ice. The weather conditions had a significant impact on the radiometric signatures of some ice types (snow-covered compact pack ice and frost-covered new ice); the impact was the highest at 94 GHz. In all cases the overall classification accuracy was around 90% (the kappa coefficient was from 0.86 to 0.96) when the optimum channel combination (24/34 GHz and 94 GHz) was used.

  4. Study of recreational land and open space using Skylab imagery. [snow and ice hydrology of southeast Michigan

    NASA Technical Reports Server (NTRS)

    Sattinger, I. J. (principal investigator)

    1974-01-01

    The author has identified the following significant results. Despite almost uniform surface temperature conditions in the study area, the thermal imagery did illustrate the following possible uses: (1) Surface temperatures relative to 0 C reveal whether the snow and ice cover is wet and the melt pattern. This information is useful in hydrologic monitoring of runoff timing and rate, as well as indicating trafficability conditions on the snow. (2) When the surface temperature of snow and ice is below freezing, it may serve as an indicator of spatial variation of air temperatures. This information may be used in calculating the spatial variation of surface radiation budgets, or in observing synoptic weather condition changes or local microclimatic effects. (3) Frozen inland lakes with less than about three or four inches of snow over the ice may be differentiated from surrounding snow covered land areas; this is not always feasible in visible wavelength imagery. The feasibility of this application decreases as the ice thickness increases.

  5. Dirty snow after nuclear war

    NASA Technical Reports Server (NTRS)

    Warren, S. G.; Wiscombe, W. J.

    1985-01-01

    It is shown that smoke from fires started by nuclear explosions could continue to cause significant disruption even after it has fallen from the atmosphere, by lowering the reflectivity of snow and sea ice surfaces, with possible effects on climate in northern latitudes caused by enhanced absorption of sunlight. The reduced reflectivity could persist for several years on Arctic sea ice and on the ablation area of the Greenland ice sheet.

  6. Contrasts in Arctic shelf sea-ice regimes and some implications: Beaufort Sea versus Laptev Sea

    USGS Publications Warehouse

    Reimnitz, E.; Dethleff, D.; Nurnberg, D.

    1994-01-01

    The winter ice-regime of the 500 km) from the mainland than in the Beaufort Sea. As a result, the annual freeze-up does not incorporate old, deep-draft ice, and with a lack of compression, such deep-draft ice is not generated in situ, as on the Beaufort Sea shelf. The Laptev Sea has as much as 1000 km of fetch at the end of summer, when freezing storms move in and large (6 m) waves can form. Also, for the first three winter months, the polynya lies inshore at a water depth of only 10 m. Turbulence and freezing are excellent conditions for sediment entrainment by frazil and anchor ice, when compared to conditions in the short-fetched Beaufort Sea. We expect entrainment to occur yearly. Different from the intensely ice-gouged Beaufort Sea shelf, hydraulic bedforms probably dominate in the Laptev Sea. Corresponding with the large volume of ice produced, more dense water is generated in the Laptev Sea, possibly accompanied by downslope sediment transport. Thermohaline convection at the midshelf polynya, together with the reduced rate of bottom disruption by ice keels, may enhance benthic productivity and permit establishment of open-shelf benthic communities which in the Beaufort Sea can thrive only in the protection of barrier islands. Indirect evidence for high benthic productivity is found in the presence of walrus, who also require year-round open water. By contrast, lack of a suitable environment restricts walrus from the Beaufort Sea, although over 700 km farther to the south. We could speculate on other consequences of the different ice regimes in the Beaufort and Laptev Seas, but these few examples serve to point out the dangers of exptrapolating from knowledge gained in the North American Arctic to other shallow Arctic shelf settings. ?? 1994.

  7. 30-Year Satellite Record Reveals Accelerated Arctic Sea Ice Loss, Antarctic Sea Ice Trend Reversal

    NASA Technical Reports Server (NTRS)

    Cavalieri, Donald J.; Parkinson, C. L.; Vinnikov, K. Y.

    2003-01-01

    Arctic sea ice extent decreased by 0.30 plus or minus 0.03 x 10(exp 6) square kilometers per decade from 1972 through 2002, but decreased by 0.36 plus or minus 0.05 x 10(exp 6) square kilometers per decade from 1979 through 2002, indicating an acceleration of 20% in the rate of decrease. In contrast to the Arctic, the Antarctic sea ice extent decreased dramatically over the period 1973-1977, then gradually increased, with an overall 30-year trend of -0.15 plus or minus 0.08 x 10(exp 6) square kilometers per 10yr. The trend reversal is attributed to a large positive anomaly in Antarctic sea ice extent observed in the early 1970's.

  8. A destabilizing thermohaline circulation-atmosphere-sea ice feedback

    SciTech Connect

    Jayne, S.R.; Marotzke, J.

    1999-02-01

    Some of the interactions and feedbacks between the atmosphere, thermohaline circulation, and sea ice are illustrated using a simple process model. A simplified version of the annual-mean coupled ocean-atmosphere box model of Nakamura, Stone, and Marotzke is modified to include a parameterization of sea ice. The model includes the thermodynamic effects of sea ice and allows for variable coverage. It is found that the addition of sea ice introduces feedbacks that have a destabilizing influence on the thermohaline circulation: Sea ice insulates the ocean from the atmosphere, creating colder air temperatures at high latitudes, which cause larger atmospheric eddy heat and moisture transports and weaker oceanic heat transports. These in turn lead to thicker ice coverage and hence establish a positive feedback. The results indicate that generally in colder climates, the presence of sea ice may lead to a significant destabilization of the thermohaline circulation. Brine rejection by sea ice plays no important role in this model`s dynamics. The net destabilizing effect of sea ice in this model is the result of two positive feedbacks and one negative feedback and is shown to be model dependent. To date, the destabilizing feedback between atmospheric and oceanic heat fluxes, mediated by sea ice, has largely been neglected in conceptual studies of thermohaline circulation stability, but it warrants further investigation in more realistic models.

  9. Determination of Snow and Ice Surface Roughness and its Importance for Ablation

    NASA Astrophysics Data System (ADS)

    Herzfeld, U. C.; Box, J.; Steffen, K.; Mayer, H.; Caine, N.; Losleben, M.

    2004-12-01

    Study of the surface roughness of snow fields, glaciers, and ice sheets requires measurement and analysis of the surface's three-dimensional features, anisotropies, and complex microtopography. Observing that the notions of relief and surface roughness differ only with respect to scale, we consider surface roughness a spatial variable defined as the derivative of (micro)topography. Spatial snow and ice surface roughness can be measured with the Glacier Roughness Sensor, a multichannel instrument that collects data at 0.2~m across-track, 0.1~m along-track resolution and subcentimeter vertical accuracy, with differential kinematic GPS data for positioning. Roughness data are analysed using the geostatistical classification method. Results of the classification provide (1) information on the morphogenesis of snow or ice surface types of a given environment, (2) subscale information for the interpretation of satellite data and facilitate (3) segmentation of a study area into characteristic surface classes. One application is monitoring the extent of ablation in the Greenland Ice Sheet. By deriving a mathematical relationship between aerodynamic roughness length and spatial surface roughness, calculating roughness from actual observations and driving energy balance models with the range of resultant values and micro-meteorological data, it could be shown that melt energy varies with a factor of two dependent on surface roughness. Hence surface roughness is an important geophysical variable that needs to be considered in any scenario of a warming ice sheet.

  10. Implications of Arctic Sea Ice Decline for the Earth System

    NASA Technical Reports Server (NTRS)

    Bhatt, Uma S.; Walker, Donald A.; Walsh, John E.; Carmack, Eddy C.; Frey, Karen E.; Meier, Walter N.; Moore, Sue E.; Parmentier, Frans-Jan W.; Post, Eric; Romanovsky, Vladimir E.; Simpson, William R.

    2014-01-01

    Arctic sea ice decline has led to an amplification of surface warming and is projected to continue to decline from anthropogenic forcing, although the exact timing of ice-free summers is uncertain owing to large natural variability. Sea ice reductions affect surface heating patterns and the atmospheric pressure distribution, which may alter midlatitude extreme weather patterns. Increased light penetration and nutrient availability during spring from earlier ice breakup enhances primary production in the Arctic Ocean and its adjacent shelf seas. Ice-obligate marine mammals may be losers, whereas seasonally migrant species may be winners from rapid sea ice decline. Tundra greening is occurring across most of the Arctic, driven primarily by warming temperatures, and is displaying complex spatial patterns that are likely tied to other factors. Sea ice changes are affecting greenhouse gas exchanges as well as halogen chemistry in the Arctic. This review highlights the heterogeneous nature of Arctic change, which is vital for researchers to better understand.

  11. Modeling brine and nutrient dynamics in Antarctic sea ice: The case of dissolved silica

    NASA Astrophysics Data System (ADS)

    Vancoppenolle, Martin; Goosse, Hugues; de Montety, Anne; Fichefet, Thierry; Tremblay, Bruno; Tison, Jean-Louis

    2010-02-01

    Sea ice ecosystems are characterized by microalgae living in brine inclusions. The growth rate of ice algae depends on light and nutrient supply. Here, the interactions between nutrients and brine dynamics under the influence of algae are investigated using a one-dimensional model. The model includes snow and ice thermodynamics with brine physics and an idealized sea ice biological component, characterized by one nutrient, namely, dissolved silica (DSi). In the model, DSi follows brine motion and is consumed by ice algae. Depending on physical ice characteristics, the brine flow is either advective, diffusive, or turbulent. The vertical profiles of ice salinity and DSi concentration are solutions of advection-diffusion equations. The model is configured to simulate the typical thermodynamic regimes of first-year Antarctic pack ice. The simulated vertical profiles of salinity and DSi qualitatively reproduce observations. Analysis of results highlights the role of convection in the lowermost 5-10 cm of ice. Convection mixes saline, nutrient-poor brine with comparatively fresh, nutrient-rich seawater. This implies a rejection of salt to the ocean and a flux of DSi to the ice. In the presence of growing algae, the simulated ocean-to-ice DSi flux increases by 0-115% compared to an abiotic situation. In turn, primary production and brine convection act in synergy to form a nutrient pump. The other important processes are the flooding of the surface by seawater and the percolation of meltwater. The former refills nutrients near the ice surface in spring. The latter, if present, tends to expell nutrients from the ice in summer.

  12. Dual-band infrared imaging applications: Locating buried minefields, mapping sea ice, and inspecting aging aircraft

    NASA Astrophysics Data System (ADS)

    Delgrande, N. K.; Durbin, P. F.; Perkins, D. E.

    1992-09-01

    We discuss the use of dual-band infrared (DBIR) imaging for three quantitative NDE applications: location buried surrogate mines, mapping sea ice thicknesses, and inspecting subsurface flaws in aging aircraft parts. Our system of DBIR imaging offers a unique combination of thermal resolution, detectability, and interpretability. Pioneered at Lawrence Livermore Laboratory, it resolves 0.2 C differences in surface temperatures needed to identify buried mine sites and distinguish them from surface features. It produces both surface temperature and emissivity-ratio images of sea ice, needed to accurately map ice thicknesses (e.g., by first removing clutter due to snow and surface roughness effects). The DBIR imaging technique depicts subsurface flaws in composite patches and lap joints of aircraft, thus providing a needed tool for aging aircraft inspections.

  13. Dual-band infrared imaging applications: Locating buried minefields, mapping sea ice, and inspecting aging aircraft

    SciTech Connect

    Del Grande, N.K.; Durbin, P.F.; Perkins, D.E.

    1992-09-01

    We discuss the use of dual-band infrared (DBIR) imaging for three quantitative NDE applications: location buried surrogate mines, mapping sea ice thicknesses and inspecting subsurface flaws in aging aircraft parts. Our system of DBIR imaging offers a unique combination of thermal resolution, detectability, and interpretability. Pioneered at Lawrence Livermore Laboratory, it resolves 0.2 {degrees}C differences in surface temperatures needed to identify buried mine sites and distinguish them from surface features. It produces both surface temperature and emissivity-ratio images of sea ice, needed to accurately map ice thicknesses (e.g., by first removing clutter due to snow and surface roughness effects). The DBIR imaging technique depicts subsurface flaws in composite patches and lap joints of aircraft, thus providing a needed tool for aging aircraft inspections.

  14. Arctic Cyclone Breaks Up Sea Ice - Duration: 33 seconds.

    NASA Video Gallery

    A powerful storm wreaked havoc on the Arctic sea ice cover in August 2012. This visualization shows the strength and direction of the winds and their impact on the ice: the red vectors represent th...

  15. Arctic Sea Ice Changes 2011-2012 - Duration: 57 seconds.

    NASA Video Gallery

    Animation showing changes in monthly Arctic sea ice volume using data from ESA's CryoSat-2 (red dots) and estimates from the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) (solid li...

  16. Global coupled sea ice-ocean state estimation

    NASA Astrophysics Data System (ADS)

    Fenty, Ian; Menemenlis, Dimitris; Zhang, Hong

    2015-09-01

    We study the impact of synthesizing ocean and sea ice concentration data with a global, eddying coupled sea ice-ocean configuration of the Massachusetts Institute of Technology general circulation model with the goal of reproducing the 2004 three-dimensional time-evolving ice-ocean state. This work builds on the state estimation framework developed in the Estimating the Circulation and Climate of the Ocean consortium by seeking a reconstruction of the global sea ice-ocean system that is simultaneously consistent with (1) a suite of in situ and remotely-sensed ocean and ice data and (2) the physics encoded in the numerical model. This dual consistency is successfully achieved here by adjusting only the model's initial hydrographic state and its atmospheric boundary conditions such that misfits between the model and data are minimized in a least-squares sense. We show that synthesizing both ocean and sea ice concentration data is required for the model to adequately reproduce the observed details of the sea ice annual cycle in both hemispheres. Surprisingly, only modest adjustments to our first-guess atmospheric state and ocean initial conditions are necessary to achieve model-data consistency, suggesting that atmospheric reanalysis products remain a leading source of errors for sea ice-ocean model hindcasts and reanalyses. The synthesis of sea ice data is found to ameliorate misfits in the high latitude ocean, especially with respect to upper ocean stratification, temperature, and salinity. Constraining the model to sea ice concentration modestly reduces ICESat-derived Arctic ice thickness errors by improving the temporal and spatial evolution of seasonal ice. Further increases in the accuracy of global sea ice thickness in the model likely require the direct synthesis of sea ice thickness data.

  17. Archives of total mercury reconstructed with ice and snow from Greenland and the Canadian High Arctic.

    PubMed

    Zheng, Jiancheng

    2015-03-15

    This study reports total Hg concentration and atmospheric flux data from ice cores and snow/ice shallow pits from two Canadian Arctic and one Greenland glaciers, with the aim of reconstructing a high resolution record of THg deposition extending back into the pre-industrial period. An 88-m ice core (653 samples) from the NEEM glacier site in Northwest Greenland was retrieved in August 2010. The bottom sample was dated to 1748, resulting in a 262 year archive. Snow and ice samples (143 samples) were recovered from a 10.3-m pit dug on the Mt. Oxford Icefield, Nunavut, in May 2008, covering 30 years. Another 15.5-m short core drilled on the Agassiz Ice Cap, Nunavut, in April 2009 yielded 191 samples covering 74 years. Net rates of atmospheric THg deposition (FTHg) were calculated based on THg concentrations and snow accumulation rates. Results from NEEM site show that THg and FTHg range from sub-pg g(-1) to 120.6 pg g(-1) (mean=1.5 pg g(-1), n=653) and from 0.06 to 1.42 ?g m(-2) year(-1) (mean=0.25 ?g m(-2) year(-1), n=218) respectively, much lower than those found in other natural media such as sediments, peat bogs and wet precipitation. The discrepancy of FTHg found in glaciers from other natural media could mainly be due to the more severe photo-reduction and reemission of deposited oxidized Hg. This study also demonstrates that reproducible THg archives can be reconstructed with glacier ice and snow samples from Greenland and the Canadian High Arctic. The THg archive reconstructed with the short core from NEEM site is so far the longest with the highest resolution in Greenland and the Canadian High Arctic. PMID:24913889

  18. Higher Methane Emissions in Regions of Sea Ice Retreat

    NASA Astrophysics Data System (ADS)

    Parmentier, Frans-Jan W.; Zhang, Wenxin; Mi, Yanjiao; Zhu, Xudong; Miller, Paul A.; van Huissteden, Ko; Hayes, Dan; Zhuang, Qianlai; David. McGuire, A.; Christensen, Torben R.

    2014-05-01

    In recent decades, the Arctic has lost more and more sea ice, which has concurrently led to higher temperatures across the high latitudes (Screen et al., 2012). Although increasingly strong evidence exists for this link between sea ice and temperature, the extra step of linking sea ice retreat - through these climatic changes - to a change in greenhouse-gas exchange is much less clear. Recently, however, it has been suggested that methane emissions have increased while sea ice declined (Parmentier et al., 2013). This initial analysis compared average methane emissions for the Arctic Region with anomalies in the average sea ice extent, which evens out regional differences. Year-to-year variations in sea ice extent are different from region to region and would therefore impact methane emissions - through temperature - differently, too. Our goal is therefore to evaluate, with the use of models, whether methane emissions are more strongly correlated to sea ice in areas of high retreat rather than in areas that have seen little variation in sea ice. For this use, the output from three regional methane models (LPJ-GUESS WhyMe, Peatland-VU and TEM6), designed to be applied to the Arctic Region, are compared to sea ice decline. A similar spatial response to sea ice retreat by these models will increase our confidence that methane emissions in the Arctic are indeed spatially linked to sea ice decline. References: Parmentier, F. J. W., Christensen, T. R., Sørensen, L. L., Rysgaard, S., McGuire, A. D., Miller, P. A., & Walker, D. A. (2013). The impact of lower sea-ice extent on Arctic greenhouse-gas exchange. Nature Climate Change, 3, 195-202. doi:10.1038/nclimate1784 Screen, J. A., Deser, C., & Simmonds, I. (2012). Local and remote controls on observed Arctic warming. Geophysical Research Letters, 39, L10709. doi:10.1029/2012GL051598

  19. Sea ice cover in the Caspian and Aral Seas from historical and satellite data

    E-print Network

    Sea ice cover in the Caspian and Aral Seas from historical and satellite data Alexei V. Kouraeva 2004 Abstract Time and space variations of ice cover in the Caspian and Aral Seas from historical area have been computed for various regions of the Caspian and Aral Seas. These time series show

  20. Aquarius Radiometer and Scatterometer Weekly-Polar-Gridded Products to Monitor Ice Sheets, Sea Ice, and Frozen Soil

    NASA Technical Reports Server (NTRS)

    Brucker, Ludovic; Dinnat, Emmanuel; Koenig, Lora

    2014-01-01

    Space-based microwave sensors have been available for several decades, and with time more frequencies have been offered. Observations made at frequencies between 7 and 183 GHz were often used for monitoring cryospheric properties (e.g. sea ice concentration, snow accumulation, snow melt extent and duration). Since 2009, satellite observations are available at the low frequency of 1.4 GHz. Such observations are collected by the Soil Moisture and Ocean Salinity (SMOS) mission, and the AquariusSAC-D mission. Even though these missions have been designed for the monitoring of soil moisture and sea surface salinity, new applications are being developed to study the cryosphere. For instance, L-band observations can be used to monitor soil freezethaw (e.g. Rautiainen et al., 2012), and thin sea ice thickness (e.g. Kaleschke et al., 2010, Huntemann et al., 2013). Moreover, with the development of satellite missions comes the need for calibration and validation sites. These sites must have stable characteristics, such as the Antarctic Plateau (Drinkwater et al., 2004, Macelloni et al., 2013). Therefore, studying the cryosphere with 1.4 GHz observations is relevant for both science applications, and remote sensing applications.

  1. Aquarius Radiometer and Scatterometer Weekly Polar-Gridded Products to Monitor Ice Sheets, Sea Ice, and Frozen Soil

    NASA Technical Reports Server (NTRS)

    Brucker, Ludovic; Dinnat, Emmanuel; Koenig, Lora

    2014-01-01

    Space-based microwave sensors have been available for several decades, and with time more frequencies have been offered. Observations made at frequencies between 7 and 183 GHz were often used for monitoring cryospheric properties (e.g. sea ice concentration, snow accumulation, snow melt extent and duration). Since 2009, satellite observations are available at the low frequency of 1.4 GHz. Such observations are collected by the Soil Moisture and Ocean Salinity (SMOS) mission, and the Aquarius/SAC-D mission. Even though these missions have been designed for the monitoring of soil moisture and sea surface salinity, new applications are being developed to study the cryosphere. For instance, L-band observations can be used to monitor soil freeze/thaw (e.g. Rautiainen et al., 2012), and thin sea ice thickness (e.g. Kaleschke et al., 2010, Huntemann et al., 2013). Moreover, with the development of satellite missions comes the need for calibration and validation sites. These sites must have stable characteristics, such as the Antarctic Plateau (Drinkwater et al., 2004, Macelloni et al., 2013). Therefore, studying the cryosphere with 1.4 GHz observations is relevant for both science applications, and remote sensing applications.

  2. Polar Oceanography, Arctic Sea Ice and Climate

    NASA Astrophysics Data System (ADS)

    Timmermans, Mary-Louise

    2015-03-01

    Intensive sampling from oceanographic moorings, shipboard measurements, and drifting autonomous buoy systems has brought new understanding to Arctic freshwater dynamics, ocean heat and mixing processes, circulation and eddies, and atmosphere-ice-ocean interactions. Observations indicate apparently rapid changes in the basin-scale freshwater distribution that have marked effects on Arctic stratification. Recent measurements support the idea that a strengthened stratification limits the vertical flux of deep-ocean heat. All ocean layers exhibit a rich mesoscale eddy field; eddies, with scales comparable to the Rossby Deformation Radius [O(10km)], transport water and heat over long distances and enhance ocean mixing. Measurements further reveal an active submesoscale flow field in the ocean surface layer. These upper-ocean features, having length scales of a few kilometers or less, are dynamically important in that they can impede surface-layer deepening and modify heat, salt, and momentum fluxes between the surface ocean and adjacent sea-ice cover. This talk will review highlights of recent Arctic Ocean observational studies across a range of temporal and spatial scales, and outline advances in our understanding of ocean drivers of sea ice and climate change.

  3. Analysis of airborne synthetic aperture radar waveforms over arctic sea ice

    NASA Astrophysics Data System (ADS)

    Zygmuntowska, Marta; Khvorostovsky, Kirill; Sandven, Stein

    2013-04-01

    The sea ice thickness and its changes are one of the biggest uncertainties in the Arctic climate system. To address these uncertainties CryoSat has been launched in 2010. Onboard is the SAR/Interferometric Radar Altimeter (SIRAL) which uses the synthetic aperture radar technique to enhance the resolution along track. The new, improved sampling technique and the resulting changes in the signal shape lead to the question weather a distinction of different sea ice types may be possible. To answer this question we analyze radar altimeter data over the arctic ocean from CryoSats' pre-launch validation campaigns. During these campaigns the Airborne SAR/Interferometric Altimeter System ASIRAS has been operated over different surface regimes what allows for a detailed analysis of the radar waveform shape over different sea ice types. In our study we in particular investigate if the lead detection can be improved and if it is possible to distinguish between first year ice and multi year ice based on the shape of the radar echo waveform alone. We define various parameters to describe the width and strength of the returned radar waveform and select the most appropriate parameters for the surface classification. With a bayesian based method we are able to identify around 80 percent of the waveforms correctly. For the detection of leads we find the widely used threshold method sufficient enough to detect more than 90 % of the leads. However we found that the use of the maximum of the radar echo power as a classification parameter can minimize the rate of false detection compared to the widely used Pulse Peakiness parameter. The possibility to distinguish between different ice types makes it possible to improve the freeboard retrieval and the conversion into sea ice thickness by applying more suitable values for the sea ice density and snow load. More analysis however is required to test the presented method for satellite based altimeters.

  4. The melt pond fraction and spectral sea ice albedo retrieval from MERIS data: validation and trends of sea ice albedo and melt pond fraction in the Arctic for years 2002-2011

    NASA Astrophysics Data System (ADS)

    Istomina, L.; Heygster, G.; Huntemann, M.; Schwarz, P.; Birnbaum, G.; Scharien, R.; Polashenski, C.; Perovich, D.; Zege, E.; Malinka, A.; Prikhach, A.; Katsev, I.

    2014-10-01

    The presence of melt ponds on the Arctic sea ice strongly affects the energy balance of the Arctic Ocean in summer. It affects albedo as well as transmittance through the sea ice, which has consequences on the heat balance and mass balance of sea ice. An algorithm to retrieve melt pond fraction and sea ice albedo (Zege et al., 2014) from the MEdium Resolution Imaging Spectrometer (MERIS) data is validated against aerial, ship borne and in situ campaign data. The result show the best correlation for landfast and multiyear ice of high ice concentrations (albedo: R = 0.92, RMS = 0.068, melt pond fraction: R = 0.6, RMS = 0.065). The correlation for lower ice concentrations, subpixel ice floes, blue ice and wet ice is lower due to complicated surface conditions and ice drift. Combining all aerial observations gives a mean albedo RMS equal to 0.089 and a mean melt pond fraction RMS equal to 0.22. The in situ melt pond fraction correlation is R = 0.72 with an RMS = 0.14. Ship cruise data might be affected by documentation of varying accuracy within the ASPeCT protocol, which is the reason for discrepancy between the satellite value and observed value: mean R = 0.21, mean RMS = 0.16. An additional dynamic spatial cloud filter for MERIS over snow and ice has been developed to assist with the validation on swath data. The case studies and trend analysis for the whole MERIS period (2002-2011) show pronounced and reasonable spatial features of melt pond fractions and sea ice albedo. The most prominent feature is the melt onset shifting towards spring (starting already in weeks 3 and 4 of June) within the multiyear ice area, north to the Queen Elizabeth Islands and North Greenland.

  5. Biologically-Oriented Processes in the Coastal Sea Ice Zone of the White Sea

    NASA Astrophysics Data System (ADS)

    Melnikov, I. A.

    2002-12-01

    The annual advance and retreat of sea ice is a major physical determinant of spatial and temporal changes in the structure and function of marine coastal biological communities. Sea ice biological data obtained in the tidal zone of Kandalaksha Gulf (White Sea) during 1996-2001 period will be presented. Previous observations in this area were mainly conducted during the ice-free summer season. However, there is little information on the ice-covered winter season (6-7 months duration), and, especially, on the sea-ice biology in the coastal zone within tidal regimes. During the January-May period time-series observations were conducted on transects along shorelines with coastal and fast ice. Trends in the annual extent of sea ice showed significant impacts on ice-associated biological communities. Three types of sea ice impact on kelps, balanoides, littorinas and amphipods are distinguished: (i) positive, when sea ice protects these populations from grinding (ii) negative, when ice grinds both fauna and flora, and (iii) a combined effect, when fast ice protects, but anchored ice grinds plant and animals. To understand the full spectrum of ecological problems caused by pollution on the coastal zone, as well as the problems of sea ice melting caused by global warming, an integrated, long-term study of the physical, chemical, and biological processes is needed.

  6. State estimation of the Labrador Sea with a coupled sea ice-ocean adjoint model

    E-print Network

    Fenty, Ian Gouverneur

    2010-01-01

    Sea ice (SI) and ocean variability in marginal polar and subpolar seas are closely coupled. SI variability in the Labrador Sea is of climatic interest because of its relationship to deep convection/mode water formation, ...

  7. A laboratory investigation into microwave backscattering from sea ice. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Bredow, Jonathan W.

    1989-01-01

    The sources of scattering of artificial sea ice were determined, backscatter measurements semi-quantitatively were compared with theoretical predictions, and inexpensive polarimetric radars were developed for sea ice backscatter studies. A brief review of the dielectric properties of sea ice and of commonly used surface and volume scattering theories is presented. A description is provided of the backscatter measurements performed and experimental techniques used. The development of inexpensive short-range polarimetric radars is discussed. The steps taken to add polarimetric capability to a simple FM-W radar are considered as are sample polarimetric phase measurements of the radar. Ice surface characterization data and techniques are discussed, including computation of surface rms height and correlation length and air bubble distribution statistics. A method is also presented of estimating the standard deviation of rms height and correlation length for cases of few data points. Comparisons were made of backscatter measurements and theory. It was determined that backscatter from an extremely smooth saline ice surface at C band cannot be attributed only to surface scatter. It was found that snow cover had a significant influence on backscatter from extremely smooth saline ice at C band.

  8. The Louvain-La-Neuve sea ice model LIM3.6: global and regional capabilities

    NASA Astrophysics Data System (ADS)

    Rousset, C.; Vancoppenolle, M.; Madec, G.; Fichefet, T.; Flavoni, S.; Barthélemy, A.; Benshila, R.; Chanut, J.; Levy, C.; Masson, S.; Vivier, F.

    2015-10-01

    The new 3.6 version of the Louvain-la-Neuve sea ice model (LIM) is presented, as integrated in the most recent stable release of Nucleus for European Modelling of the Ocean (NEMO) (3.6). The release will be used for the next Climate Model Inter-comparison Project (CMIP6). Developments focussed around three axes: improvements of robustness, versatility and sophistication of the code, which involved numerous changes. Robustness was improved by enforcing exact conservation through the inspection of the different processes driving the air-ice-ocean exchanges of heat, mass and salt. Versatility was enhanced by implementing lateral boundary conditions for sea ice and more flexible ice thickness categories. The latter includes a more practical computation of category boundaries, parameterizations to use LIM3.6 with a single ice category and a flux redistributor for coupling with atmospheric models that cannot handle multiple sub-grid fluxes. Sophistication was upgraded by including the effect of ice and snow weight on the sea surface. We illustrate some of the new capabilities of the code in two standard simulations. One is an ORCA2-LIM3 global simulation at a nominal 2° resolution, forced by reference atmospheric climatologies. The other one is a regional simulation at 2 km resolution around the Svalbard Archipelago in the Arctic Ocean, with open boundaries and tides. We show that the LIM3.6 forms a solid and flexible base for future scientific studies and model developments.

  9. Sensitivity of CryoSat-2 Arctic sea-ice freeboard and thickness on radar-waveform interpretation

    NASA Astrophysics Data System (ADS)

    Ricker, R.; Hendricks, S.; Helm, V.; Skourup, H.; Davidson, M.

    2014-08-01

    In the context of quantifying Arctic ice-volume decrease at global scale, the CryoSat-2 satellite was launched in 2010 and is equipped with the Ku band synthetic aperture radar altimeter SIRAL (Synthetic Aperture Interferometric Radar Altimeter), which we use to derive sea-ice freeboard defined as the height of the ice surface above the sea level. Accurate CryoSat-2 range measurements over open water and the ice surface of the order of centimetres are necessary to achieve the required accuracy of the freeboard-to-thickness conversion. Besides uncertainties of the actual sea-surface height and limited knowledge of ice and snow properties, the composition of radar backscatter and therefore the interpretation of radar echoes is crucial. This has consequences in the selection of retracker algorithms which are used to track the main scattering horizon and assign a range estimate to each CryoSat-2 measurement. In this study we apply a retracker algorithm with thresholds of 40, 50 and 80% of the first maximum of radar echo power, spanning the range of values used in the current literature. By using the selected retrackers and additionally results from airborne validation measurements, we evaluate the uncertainties of sea-ice freeboard and higher-level products that arise from the choice of the retracker threshold only, independent of the uncertainties related to snow and ice properties. Our study shows that the choice of retracker thresholds does have a significant impact on magnitudes of estimates of sea-ice freeboard and thickness, but that the spatial distributions of these parameters are less affected. Specifically we find mean radar freeboard values of 0.121 m (0.265 m) for the 40% threshold, 0.086 m (0.203 m) for the 50% threshold and 0.024 m (0.092 m) for the 80% threshold, considering first-year ice (multiyear ice) in March 2013. We show that the main source of freeboard and thickness uncertainty results from the choice of the retracker and the unknown penetration of the radar pulse into the snow layer in conjunction with surface roughness effects. These uncertainties can cause a freeboard bias of roughly 0.06-0.12 m. Furthermore we obtain a significant rise of 0.02-0.15 m of freeboard from March 2013 to November 2013 in the area for multiyear sea ice north of Greenland and Canada. Since this is unlikely, it gives rise to the assumption that applying different retracker thresholds depending on seasonal properties of the snow load is necessary in the future.

  10. neXtSIM: a new Lagrangian sea ice model

    NASA Astrophysics Data System (ADS)

    Rampal, P.; Bouillon, S.; Ólason, E.; Morlighem, M.

    2015-10-01

    The Arctic sea ice cover has changed drastically over the last decades. Associated with these changes is a shift in dynamical regime seen by an increase of extreme fracturing events and an acceleration of sea ice drift. The highly non-linear dynamical response of sea ice to external forcing makes modelling these changes, and the future evolution of Arctic sea ice a challenge for current models. It is, however, increasingly important that this challenge be better met, both because of the important role of sea ice in the climate system and because of the steady increase of industrial operations in the Arctic. In this paper we present a new dynamical/thermodynamical sea ice model, called neXtSIM in order to address this. neXtSIM is a continuous and fully Lagrangian model, and the equations are discretised with the finite-element method. In this model, sea ice physics are driven by a synergic combination of two core components: a model for sea ice dynamics built on a new mechanical framework using an elasto-brittle rheology, and a model for sea ice thermodynamics providing damage healing for the mechanical framework. The results of a thorough evaluation of the model performance for the Arctic are presented for the period September 2007 to October 2008. They show that observed multi-scale statistical properties of sea ice drift and deformation are well captured as well as the seasonal cycles of ice volume, area, and extent. These results show that neXtSIM is a very promising tool for simulating the sea ice over a wide range of spatial and temporal scales.

  11. Winter observations of CO2 exchange between sea ice and the atmosphere in a coastal fjord environment

    NASA Astrophysics Data System (ADS)

    Sievers, J.; Sørensen, L. L.; Papakyriakou, T.; Else, B.; Sejr, M. K.; Haubjerg Søgaard, D.; Barber, D.; Rysgaard, S.

    2015-08-01

    Eddy covariance observations of CO2 fluxes were conducted during March-April 2012 in a temporally sequential order for 8, 4 and 30 days, respectively, at three locations on fast sea ice and on newly formed polynya ice in a coastal fjord environment in northeast Greenland. CO2 fluxes at the sites characterized by fast sea ice (ICEI and DNB) were found to increasingly reflect periods of strong outgassing in accordance with the progression of springtime warming and the occurrence of strong wind events: FCO2ICE1 = 1.73 ± 5 mmol m-2 day-1 and FCO2DNB = 8.64 ± 39.64 mmol m-2 day-1, while CO2 fluxes at the polynya site (POLYI) were found to generally reflect uptake FCO2POLY1 = -9.97 ± 19.8 mmol m-2 day-1. Values given are the mean and standard deviation, and negative/positive values indicate uptake/outgassing, respectively. A diurnal correlation analysis supports a significant connection between site energetics and CO2 fluxes linked to a number of possible thermally driven processes, which are thought to change the pCO2 gradient at the snow-ice interface. The relative influence of these processes on atmospheric exchanges likely depends on the thickness of the ice. Specifically, the study indicates a predominant influence of brine volume expansion/contraction, brine dissolution/concentration and calcium carbonate formation/dissolution at sites characterized by a thick sea-ice cover, such that surface warming leads to an uptake of CO2 and vice versa, while convective overturning within the sea-ice brines dominate at sites characterized by comparatively thin sea-ice cover, such that nighttime surface cooling leads to an uptake of CO2 to the extent permitted by simultaneous formation of superimposed ice in the lower snow column.

  12. Autonomous Observations of the Heat and Mass Balance of Arctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Perovich, D. K.; Richter-Menge, J.; Arntsen, A. E.; Polashenski, C.; Elder, B. C.

    2014-12-01

    For the past decade the Arctic Observing Network included autonomous measurements of the mass balance of Arctic sea ice. A system of Ice Mass Balance (IMB) buoys measured time series of snow accumulation and ablation; ice growth and surface and bottom melt; and vertical profiles of air, snow, ice, and ocean temperature. The mass balance is the great integrator of heat and can be used to derive estimates of both the surface heat budget and ocean heat flux. Large spatial and interannual variations in surface and bottom melting are evident in the data record. For example, over the western Arctic the observed total summer surface melting ranges from as little as 0.05 m to over 0.75 m. Bottom melting exhibits an even more extreme range varying from 0.1 to 2.2 m. IMBs in the Beaufort Sea and Central Arctic during the summer of 2013 are selected for more detailed analysis, calculating the time series of net surface energy budget and of the ocean heat flux. Ice temperature profiles are used to determine internal melting of the ice. Results from these buoys are integrated with high resolution satellite imagery to examine the heat and mass balance on the aggregate scale. Incident solar radiation is obtained from reanalysis products and used to calculate solar heat input to leads and to the upper ocean. Floe perimeter, ice motion, and lead heat content are combined to estimate the amount of lateral melting. From this integrated analysis, summer ice losses due to surface, bottom, lateral, and internal melting are computed on the aggregate scale and compared regionally.

  13. The National Snow and Ice Data Center's Polar Pathfinder Sampler CD-ROM

    NASA Astrophysics Data System (ADS)

    Thrasher Hybl, T. L.; Khalsa, S. S.; Holm, M.

    2001-05-01

    The NOAA/NASA Pathfinder Program is designed to facilitate user access to earth science data sets which address global change concerns. The Polar Pathfinders, a subgroup of the Pathfinder Program, addresses the comparison of parameters from different data sets with a common projection (the NSIDC Equal-Area Scalable Earth-Grid (EASE-Grid)), file naming conventions, and validation conventions. This ensures that consistently processed data sets are available to the cryospheric science community, for comparing and contrasting. The National Snow and Ice Data Center (NSIDC) has produced a CD-ROM called, "Polar Pathfinder Sampler: Combined AVHRR, SMMR-SSM/I, and TOVS Time Series and Samples." This CD-ROM includes sample data, time-series visualizations, and browse products, for temporal and spatial subsets of the AVHRR, SMMR-SSM/I and TOVS data sets, to illustrate the types of products available for the various data sets. Also included on this CD-ROM is the P-Cube, a multidimensional structure combining arctic SSM/I, AVHRR and TOVS data. The data highlighted on this CD-ROM serve a wide range of polar climate research applications, but are of particular interest to researchers working on large-scale atmospheric changes, sea ice modeling, and surface heat and mass balance studies. AVHRR products for both hemispheres, at 1.25 and 5 km resolutions, include calibrated channel data, surface broadband albedo, surface temperature, and ancillary data so that users can apply algorithms of their choice to calculate albedo and surface temperature. SSM/I brightness temperature data and time files are included, in each of three projections: Northern and Southern Hemispheres and an equatorial cylindrical projection. TOVS parameters derived from arctic (poleward of 60 degrees north latitude) radiances include atmospheric temperature profiles, water vapor, surface temperature, total effective cloud fraction, cloud top pressure and temperature, turning angle between geostrophic wind and surface stress over ice, emissivity, boundary layer stratification and geostrophic drag coefficient. The P-Cube combines arctic SSM/I, AVHRR and TOVS data, all mapped to a 100 km resolution EASE-Grid, thereby facilitating study of polar processes and interactions among them using data from multiple sensors. The current prototype version of the P-Cube includes the most important parameters from the three Polar Pathfinders noted above, and the temporal coverage extends from 1 January 1988 to 31 December 1989. Future versions of the P-Cube will have expanded temporal and spatial coverage, as well as additional parameters. Featured data products and tools on the Polar Pathfinder Sampler CD-ROM will be presented.

  14. Earth Observing System (EOS) Snow and Ice Products for Observation and Modeling

    NASA Technical Reports Server (NTRS)

    Hall, D.; Kaminski, M.; Cavalieri, D.; Dickinson, R.; Marquis, M.; Riggs, G.; Robinson, D.; VanWoert, M.; Wolfe, R.

    2005-01-01

    Snow and ice are the key components of the Earth's cryosphere, and their influence on the Earth's energy balance is very significant due at least in part to the large areal extent and high albedo characterizing these features. Large changes in the cryosphere have been measured over the last century and especially over the past decade, and remote sensing plays a pivotal role in documenting these changes. Many of NASA's Earth Observing System (EOS) products derived from instruments on the Terra, Aqua, and Ice, Cloud and land Elevation Satellite (ICESat) satellites are useful for measuring changes in features that are associated with climate change. The utility of the products is continually enhanced as the length of the time series increases. To gain a more coherent view of the cryosphere and its historical and recent changes, the EOS products may be employed together, in conjunction with other sources of data, and in models. To further this goal, the first EOS Snow and Ice Products Workshop was convened. The specific goals of the workshop were to provide current and prospective users of EOS snow and ice products up-to-date information on the products, their validation status and future enhancements, to help users utilize the data products through hands-on demonstrations, and to facilitate the integration of EOS products into models. Oral and poster sessions representing a wide variety of snow and ice topics were held; three panels were also convened to discuss workshop themes. Panel discussions focused on data fusion and assimilation of the products into models. Approximately 110 people attended, representing a wide array of interests and organizations in the cryospheric community.

  15. Arctic Ocean Sea Ice Thickness, Bathymetry, and Water Properties from Submarine Data

    NASA Astrophysics Data System (ADS)

    Windnagel, A. K.; Fetterer, F. M.

    2014-12-01

    The Submarine Arctic Science Program, SCICEX, is a federal interagency collaboration that began in 1993 among the operational Navy, research agencies, and the marine research community to use nuclear-powered submarines for scientific studies of the Arctic Ocean. Unlike surface ships and satellites, submarines have the unique ability to operate and take measurements regardless of sea ice cover, weather conditions, and time of year. This allows for a broad and comprehensive investigation of an entire ocean basin. The goal of the program is to acquire comprehensive data about Arctic sea ice thickness; biological, chemical, and hydrographic water properties; and bathymetry to improve our understanding of the Arctic Ocean basin and its role in the Earth's climate system. Ice draft is measured with upward looking sonars mounted on the submarine's hull. The work of collaborators on the SCICEX project compared recent ice draft from the submarines with draft from the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) and with ice thickness estimates from ice age and have shown that SCICEX ice draft are consistent with these models. Bathymetry is measured with a bottom sounder. SCICEX bathymetry data from 1993 to 1999 are included in the International Bathymetric Chart of the Arctic Ocean (IBCAO). Collaborators have compared more recent bathymetry data collected through the SCICEX project with other IBCAO data, and they agree well. Water properties are measured with two different types of conductivity, temperature, and depth (CTD) sensors: one mounted on the submarine's hull and expendable versions that are deployed through the submarines torpedo tubes. Data from the two different CTD sensors validate one another. The breadth of instrumentation available from submarines along with their ability to be unencumbered by sea ice, weather, and season makes the data they have collected extremely valuable. The National Snow and Ice Data Center (NSIDC) manages this data collection and makes it available through the web at http://nsidc.org/scicex.

  16. Reducing uncertainty in high-resolution sea ice models.

    SciTech Connect

    Peterson, Kara J.; Bochev, Pavel Blagoveston

    2013-07-01

    Arctic sea ice is an important component of the global climate system, reflecting a significant amount of solar radiation, insulating the ocean from the atmosphere and influencing ocean circulation by modifying the salinity of the upper ocean. The thickness and extent of Arctic sea ice have shown a significant decline in recent decades with implications for global climate as well as regional geopolitics. Increasing interest in exploration as well as climate feedback effects make predictive mathematical modeling of sea ice a task of tremendous practical import. Satellite data obtained over the last few decades have provided a wealth of information on sea ice motion and deformation. The data clearly show that ice deformation is focused along narrow linear features and this type of deformation is not well-represented in existing models. To improve sea ice dynamics we have incorporated an anisotropic rheology into the Los Alamos National Laboratory global sea ice model, CICE. Sensitivity analyses were performed using the Design Analysis Kit for Optimization and Terascale Applications (DAKOTA) to determine the impact of material parameters on sea ice response functions. Two material strength parameters that exhibited the most significant impact on responses were further analyzed to evaluate their influence on quantitative comparisons between model output and data. The sensitivity analysis along with ten year model runs indicate that while the anisotropic rheology provides some benefit in velocity predictions, additional improvements are required to make this material model a viable alternative for global sea ice simulations.

  17. Higher Methane Emissions in Regions of Sea Ice Retreat

    NASA Astrophysics Data System (ADS)

    Parmentier, F. J. W.; Zhang, W.; Mi, Y.; Zhu, X.; Miller, P. A.; van Huissteden, K. J.; Hayes, D. J.; Zhuang, Q.; McGuire, A. D.; Christensen, T. R.

    2014-12-01

    Arctic sea ice has seen a tremendous decline in recent decades, concurrently leading to higher temperatures across the high latitudes. Although increasingly strong evidence exists for this link between sea ice and temperature, the extra step of linking sea ice retreat - through these climatic changes - to a change in greenhouse-gas exchange is much less obvious. Recently, however, it has been suggested that methane emissions have increased as sea ice declined (Parmentier et al., 2013), leading to concerns that sea ice decline has led to a perturbation of the terrestrial component of the Arctic greenhouse gas balance. This initial analysis, however, compared average methane emissions of the Arctic Region with anomalies in the average sea ice extent for the entire summer, which evens out regional and temporal differences. The pattern of year-to-year fluctuations in sea ice extent varies from region to region and the impact on methane emissions - through temperature - is therefore expected to vary spatially, too. Our goal is thus to elucidate to what degree a correlation between methane emissions and sea ice exists in areas of high retreat compared to areas that have seen less sea ice decline. In addition, the impact of sea ice retreat on methane emissions is investigated throughout the melt season to identify those periods in which the teleconnection between sea ice and methane emissions is most pronounced. To this purpose, the output from three regional methane models (LPJ-GUESS WhyMe, Peatland-VU and TEM6) has been compared to independent observations of sea ice extent, and subjected to a rigorous spatial and temporal analysis. A similar response to sea ice retreat among these models will increase our confidence that teleconnections between methane emissions and sea ice decline exist within the Arctic. References: Parmentier, F. J. W., Christensen, T. R., Sørensen, L. L., Rysgaard, S., McGuire, A. D., Miller, P. A., & Walker, D. A. (2013). The impact of lower sea-ice extent on Arctic greenhouse-gas exchange. Nature Climate Change, 3, 195-202. doi:10.1038/nclimate1784

  18. ARISE (Antarctic Remote Ice Sensing Experiment) in the East 2003: Validation of Satellite-derived Sea-ice Data Product

    NASA Technical Reports Server (NTRS)

    Massom, Robert A.; Worby, Anthony; Lytle, Victoria; Markus, Thorsten; Allison, Ian; Scambos, Theodore; Enomoto, Hiroyuki; Tateyama, Kazutaka; Haran, Terence; Comiso, Josefino C.; Pfaffling, Andreas; Tamura, Takeshi; Muto, Atsuhiro; Kanagaratnam, Pannir; Giles, Barry; Young, Neal; Hyland, Glenn; Key, Erica

    2006-01-01

    Preliminary results are presented from the first validation of geophysical data products (ice concentration, snow thickness on sea ice (h(sub s) and ice temperature (T(sub i))fr om the NASA EOS Aqua AMSR-E sensor, in East Antarctica (in September-October 2003). The challenge of collecting sufficient measurements with which to validate the coarse-resolution AMSR-E data products adequately was addressed by means of a hierarchical approach, using detailed in situ measurements, digital aerial photography and other satellite data. Initial results from a circumnavigation of the experimental site indicate that, at least under cold conditions with a dry snow cover, there is a reasonably close agreement between satellite- and aerial-photo-derived ice concentrations, i.e. 97.2+/-.6% for NT2 and 96.5+/-2.5% for BBA algorithms vs 94.3% for the aerial photos. In general, the AMSR-E concentration represents a slight overestimate of the actual concentration, with the largest discrepancies occurring in regions containing a relatively high proportion of thin ice. The AMSR-E concentrations from the NT2 and BBA algorithms are similar on average, although differences of up to 5% occur in places, again related to thin-ice distribution. The AMSR-E ice temperature (T(sub i)) product agrees with coincident surface measurements to approximately 0.5 C in the limited dataset analyzed. Regarding snow thickness, the AMSR h(sub s) retrieval is a significant underestimate compared to in situ measurements weighted by the percentage of thin ice (and open water) present. For the case study analyzed, the underestimate was 46% for the overall average, but 23% compared to smooth-ice measurements. The spatial distribution of the AMSR-E h(sub s) product follows an expected and consistent spatial pattern, suggesting that the observed difference may be an offset (at least under freezing conditions). Areas of discrepancy are identified, and the need for future work using the more extensive dataset is highlighted.

  19. Supplementary Information for "Halogen Activation via Interactions with Environmental Ice and Snow": Photolysis lifetimes of halogen-containing species

    E-print Network

    Meskhidze, Nicholas

    Supplementary Information for "Halogen Activation via Interactions with Environmental Ice and Snow": Photolysis lifetimes of halogen-containing species in snowpack Snowpack of the review, calculations are presented for the photolysis lifetimes of a number of halogenated

  20. On the origin and evolution of sea-ice anomalies in the Beaufort-Chukchi Sea

    NASA Astrophysics Data System (ADS)

    Tremblay, L.-B.; Mysak, L. A.

    The origin and space-time evolution of Beaufort-Chukchi Sea ice anomalies are studied using data and a recently developed dynamic-thermodynamic sea-ice model. First, the relative importance of anomalies of river runoff, atmospheric temperature and wind in creating anomalous sea-ice conditions in the Beaufort-Chukchi Sea is investigated. The results indicate that wind anomalies are the dominant factor responsible for creating interannual variability in the Beaufort-Chukchi Sea ice cover. Temperature anomalies appear to play a major role for longer time scale fluctuations, whereas the effects of runoff anomalies are small. The sea-ice model is then used to track the position of a positive sea-ice anomaly as it is transported by the Beaufort Gyre toward the Transpolar Drift Stream and then exported out of the Arctic Basin into the Greenland Sea via Fram Strait. The model integration shows that sea-ice anomalies originating in the western Beaufort Sea can survive a few seasonal cycles as they propogate through the Arctic Basin and can account for a notable amount of anomalous ice export into the Greenland Sea. These anomalies, however, represent a small contribution to the fresh water budget in this area when compared with sea-ice fluctuations generated by interannually varying local winds.

  1. An improved CryoSat-2 sea ice freeboard and thickness retrieval algorithm through the use of waveform fitting

    NASA Astrophysics Data System (ADS)

    Kurtz, N. T.; Galin, N.; Studinger, M.

    2014-01-01

    We develop an empirical model capable of simulating the mean echo power cross product of CryoSat-2 SAR and SARIn mode waveforms over sea ice covered regions. The model simulations are used to show the importance of variations in the radar backscatter coefficient with incidence angle and surface roughness for the retrieval of surface elevation of both sea ice floes and leads. The numerical model is used to fit CryoSat-2 waveforms to enable retrieval of surface elevation through the use of look-up tables and a bounded trust region Newton least squares fitting approach. The use of a model to fit returns from sea ice regions offers advantages over currently used threshold retracking methods which are here shown to be sensitive to the combined effect of bandwidth limited range resolution and surface roughness variations. Laxon et al. (2013) have compared ice thickness results from CryoSat-2 and IceBridge, and found good agreement, however consistent assumptions about the snow depth and density of sea ice were not used in the comparisons. To address this issue, we directly compare ice freeboard and thickness retrievals from the waveform fitting and threshold tracker methods of CryoSat-2 to Operation IceBridge data using a consistent set of parameterizations. For three IceBridge campaign periods from March 2011-2013, mean differences (CryoSat-2 - IceBridge) of 0.144 m and 1.351 m are respectively found between the freeboard and thickness retrievals using a 50% sea ice floe threshold retracker, while mean differences of 0.019 m and 0.182 m are found when using the waveform fitting method. This suggests the waveform fitting technique is capable of better reconciling the sea ice thickness data record from laser and radar altimetry data sets through the usage of consistent physical assumptions.

  2. 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.

  3. Holocene sea surface temperature and sea ice extent in the Okhotsk and Bering Seas

    NASA Astrophysics Data System (ADS)

    Harada, Naomi; Katsuki, Kota; Nakagawa, Mitsuhiro; Matsumoto, Akiko; Seki, Osamu; Addison, Jason A.; Finney, Bruce P.; Sato, Miyako

    2014-08-01

    Accurate prediction of future climate requires an understanding of the mechanisms of the Holocene climate; however, the driving forces, mechanisms, and processes of climate change in the Holocene associated with different time scales remain unclear. We investigated the drivers of Holocene sea surface temperature (SST) and sea ice extent in the North Pacific Ocean, and the Okhotsk and Bering Seas, as inferred from sediment core records, by using the alkenone unsaturation index as a biomarker of SST and abundances of sea ice-related diatoms (F. cylindrus and F. oceanica) as an indicator of sea ice extent to explore controlling mechanisms in the high-latitude Pacific. Temporal changes in alkenone content suggest that alkenone production was relatively high during the middle Holocene in the Okhotsk Sea and the western North Pacific, but highest in the late Holocene in the eastern Bering Sea and the eastern North Pacific. The Holocene variations of alkenone-SSTs at sites near Kamchatka in the Northwest Pacific, as well as in the western and eastern regions of the Bering Sea, and in the eastern North Pacific track the changes of Holocene summer insolation at 50°N, but at other sites in the western North Pacific, in the southern Okhotsk Sea, and the eastern Bering Sea they do not. In addition to insolation, other atmosphere and ocean climate drivers, such as sea ice distribution and changes in the position and activity of the Aleutian Low, may have systematically influenced the timing and magnitude of warming and cooling during the Holocene within the subarctic North Pacific. Periods of high sea ice extent in both the Okhotsk and Bering Seas may correspond to some periods of frequent or strong winter-spring dust storms in the Mongolian Gobi Desert, particularly one centered at ?4-3 thousand years before present (kyr BP). Variation in storm activity in the Mongolian Gobi Desert region may reflect changes in the strength and positions of the Aleutian Low and Siberian High. We suggest that periods of eastward displacement or increased intensity of the Aleutian Low correspond with times of increased extent of sea ice in the western Okhotsk Sea and eastern Bering Sea.

  4. Radar backscatter measurements from Arctic sea ice during the fall freeze-up

    NASA Technical Reports Server (NTRS)

    Beaven, S.; Gogineni, S. P.; Shanableh, M.; Gow, A.; Tucker, W.; Jezek, K.

    1993-01-01

    Radar backscatter measurements from sea ice during the fall freeze-up were performed by the United States Coast Guard Icebreaker Polar Star as a part of the International Arctic Ocean Expedition (IAOE'91) from Aug. to Sep. 1991. The U.S. portion of the experiment took place on board the Polar Star and was referred to as TRAPOLEX '91 (Transpolar expedition) by some investigators. Before prematurely aborting its mission because of mechanical failure of her port shaft, the Polar Star reached 84 deg 57 min N latitude at 35 deg E longitude. The ship was in the ice (greater than 50 percent coverage) from 14 Aug. until 3 Sep. and was operational for all but 6 days due to two instances of mechanical problems with the port shaft. The second was fatal to the ship's participation in the expedition. During the expedition, radar backscatter was measured at C-band under a variety of conditions. These included measurements from young ice types as well as from multiyear and first-/second-year sea ice during the fall freeze-up. The sea ice types were determined by measurement of the ice properties at several of the stations and by visual inspection on others. Radar backscatter measurements were performed over a large portion of the ship's transit into the Arctic ice pack. These were accompanied by in situ sea ice property characterization by the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) at several stations and, when snow was present, its properties were documented by The Microwave Group, Ottawa River (MWG).

  5. A New Surface-Based Quad-Pol C-band Microwave Scatterometer for Sea Ice Investigations

    NASA Astrophysics Data System (ADS)

    Yackel, J. J.; Barber, D. G.

    2004-05-01

    Quantifying the role of seasonal Arctic sea ice processes in regional coupled ocean-sea ice-atmosphere climate models requires an improvement in our ability to characterize their physical, dynamic and thermodynamic states through a temporal continuum beginning with fall accretion and concluding with summer ablation at a variety of spatial scales. Spaceborne polarimetric microwave remote sensing will shortly evolve as a key tool for measuring, monitoring and modeling such spatio-temporal dependent sea ice states. In this paper we describe a new surface-based quad-pol C-band microwave scatterometer used to collect sea ice backscatter (normalized radar cross section - NRCS) statistics during the Canadian Arctic Shelf Exchange Study (CASES) in the Amundsen Gulf region of the western Canadian Arctic. We present initial backscatter measurements, including polarization ratios, obtained over both marginal and landfast first-year sea ice types. Preliminary results show that the scatterometer is highly sensitive to the physical structure (ie. thickness/age, surface roughness and salinity) of new and marginal ice forms and to ice surface roughness (for cold, winter first-year ice), temperature dependent brine volume near the snow - ice interface (late winter/early spring) and vertical structure of water in liquid phase within the snow cover (spring). Most NRCS measurements were found to be sensitive to the incidence angle of the sensor (15 to 60 degrees). We conclude by demonstrating the utility of the scatterometer to measure and geophysically invert various surface states throughout the winter to summer transition through our ability to upscale our in situ measurements to spaceborne acquired synthetic aperture radar (SAR) data from RADARSAT-1 SAR and EVISAT ASAR.

  6. Observation of Sea Ice Surface Thermal States Under Cloud Cover

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Perovich, D. K.; Gow, A. J.; Kwok, R.; Barber, D. G.; Comiso, J. C.; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    Clouds interfere with the distribution of short-wave and long-wave radiations over sea ice, and thereby strongly affect the surface energy balance in polar regions. To evaluate the overall effects of clouds on climatic feedback processes in the atmosphere-ice-ocean system, the challenge is to observe sea ice surface thermal states under both clear sky and cloudy conditions. From laboratory experiments, we show that C-band radar (transparent to clouds) backscatter is very sensitive to the surface temperature of first-year sea ice. The effect of sea ice surface temperature on the magnitude of backscatter change depends on the thermal regimes of sea ice thermodynamic states. For the temperature range above the mirabilite (Na2SO4.10H20) crystallization point (-8.2 C), C-band data show sea ice backscatter changes by 8-10 dB for incident angles from 20 to 35 deg at both horizontal and vertical polarizations. For temperatures below the mirabilite point but above the crystallization point of MgCl2.8H2O (-18.0 C), relatively strong backwater changes between 4-6 dB are observed. These backscatter changes correspond to approximately 8 C change in temperature for both cases. The backscattering mechanism is related to the temperature which determines the thermodynamic distribution of brine volume in the sea ice surface layer. The backscatter is positively correlated to temperature and the process is reversible with thermodynamic variations such as diurnal insolation effects. From two different dates in May 1993 with clear and overcast conditions determined by the Advanced Very High Resolution Radiometer (AVHRR), concurrent Earth Resources Satellite 1 (ERS-1) C-band ice observed with increases in backscatter over first-year sea ice, and verified by increases in in-situ sea ice surface temperatures measured at the Collaborative-Interdisciplinary Cryosphere Experiment (C-ICE) site.

  7. (Reduce uncertainty in projection of future sea-level change due to ice wastage)

    SciTech Connect

    Meier, M.F.

    1991-01-01

    Three basic goals were stated in the original proposal. These were: (1) develop an understanding of the heat and mass flow into subfreezing snow and firn, in order to model the evolution of the temperature distribution and the infiltration rates through the firn; (2) relate changes in climate, as given by general circulation model predictions, to changes in the surface mass and energy balances of glaciers; and (3) use the above results to analyze the effects of changed surface mass and energy balances on the flow of meltwater through snow and firn, and on the runoff from these glaciers, in a CO{sub 2}-affected climate. This final report summarizes our progress toward these goals. The primary product of this research program has been the communication of this progress in the form of publications in the scientific literature and presentations at scientific meetings. Our research activities in the past three years have provided a new basis for modeling of multiphase flow in subfreezing snow, new field data on the structural properties of arctic firn pertinent to hydrological modeling, and estimates of sea level change in response to changing patterns of runoff from the Greenland Ice Sheet. We conclude that forecasts of future sea level changes from all glacier runoff sources may be in error by amounts on the order of +8 cm over the next 150 years, due to the lag in generating runoff to the sea. Our specific research products include two distributed-parameter models of water flow through snow with melting and freezing, a theoretical model of wetting-front advance into subfreezing snow for inclusion in a future model, and a simple large-scale model of the response of Greenland runoff in a changing climate which provides estimates of the effect of melt water refreezing phenomena on sea level changes in response to a range of possible future climates.

  8. Determining the contribution of singlet molecular oxygen to the decay of pollutants on snow and ice

    NASA Astrophysics Data System (ADS)

    Bower, J. P.; Anastasio, C.

    2009-12-01

    Singlet molecular oxygen (1O2*) reacts rapidly with certain types of environmental pollutants such as furans, phenols, and polycyclic aromatic hydrocarbons (PAHs). It is formed when a sensitizer, or chromophore, absorbs light and subsequently transfers energy to dissolved oxygen. 1O2* chemistry has been studied primarily in the aqueous phase, such as in surface waters or cloud and fog drops. In our prior work, we showed that the rate of formation (Rf) and steady state concentration ([1O2*]) of 1O2* can be orders of magnitude higher in frozen solutions, relative to those in the liquid phase. Here we investigate methods to discern the contribution of 1O2* - rather than oxidants such as hydroxyl radical (?OH) - to the decay of pollutants on snow and ice. Ice and liquid samples containing a known sensitizer (Rose Bengal) for 1O2* were illuminated in a temperature-controlled solar simulator. Following illumination, the decay of our probe species (furfuryl alcohol) was measured using high performance liquid chromatography. Initial tests were conducted in laboratory solutions made to simulate the concentrations and characteristics of natural (melted) snow, with low concentrations of glycerol added to simulate natural scavengers of ?OH. We show our method to detect reactions by 1O2* apart from other oxidants, particularly ?OH, and show examples of its application in real snow samples. The results of these experiments will allow us to determine the contribution of 1O2* to the decay of the pollutant species in illuminated snow.

  9. Light-absorbing particles in snow and ice: Measurement and modeling of climatic and hydrological impact

    NASA Astrophysics Data System (ADS)

    Qian, Yun; Yasunari, Teppei J.; Doherty, Sarah J.; Flanner, Mark G.; Lau, William K. M.; Ming, Jing; Wang, Hailong; Wang, Mo; Warren, Stephen G.; Zhang, Rudong

    2015-01-01

    Light absorbing particles (LAP, e.g., black carbon, brown carbon, and dust) influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric heating by absorption of solar radiation and interactions with clouds, LAP in snow on land and ice can reduce the surface reflectance (a.k.a., surface darkening), which is likely to accelerate the snow aging process and further reduces snow albedo and increases the speed of snowpack melt. LAP in snow and ice (LAPSI) has been identified as one of major forcings affecting climate change, e.g. in the fourth and fifth assessment reports of IPCC. However, the uncertainty level in quantifying this effect remains very high. In this review paper, we document various technical methods of measuring LAPSI and review the progress made in measuring the LAPSI in Arctic, Tibetan Plateau and other mid-latitude regions. We also report the progress in modeling the mass concentrations, albedo reduction, radiative forcing, and climatic and hydrological impact of LAPSI at global and regional scales. Finally we identify some research needs for reducing the uncertainties in the impact of LAPSI on global and regional climate and the hydrological cycle.

  10. Light-absorbing Particles in Snow and Ice: Measurement and Modeling of Climatic and Hydrological Impact

    SciTech Connect

    Qian, Yun; Yasunari, Teppei J.; Doherty, Sarah J.; Flanner, M. G.; Lau, William K.; Ming, J.; Wang, Hailong; Wang, Mo; Warren, Stephen G.; Zhang, Rudong

    2015-01-01

    Light absorbing particles (LAP, e.g., black carbon, brown carbon, and dust) influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric heating by absorption of solar radiation and interactions with clouds, LAP in snow on land and ice can reduce the surface reflectance (a.k.a., surface darkening), which is likely to accelerate the snow aging process and further reduces snow albedo and increases the speed of snowpack melt. LAP in snow and ice (LAPSI) has been identified as one of major forcings affecting climate change, e.g. in the fourth and fifth assessment reports of IPCC. However, the uncertainty level in quantifying this effect remains very high. In this review paper, we document various technical methods of measuring LAPSI and review the progress made in measuring the LAPSI in Arctic, Tibetan Plateau and other mid-latitude regions. We also report the progress in modeling the mass concentrations, albedo reduction, radiative forcing, andclimatic and hydrological impact of LAPSI at global and regional scales. Finally we identify some research needs for reducing the uncertainties in the impact of LAPSI on global and regional climate and the hydrological cycle.

  11. Light-Absorbing Particles in Snow and Ice: Measurement and Modeling of Climatic and Hydrological Impact

    NASA Technical Reports Server (NTRS)

    Qian, Yun; Yasunari, Teppei J.; Doherty, Sarah J.; Flanner, Mark G.; Lau, William K. M.; Ming, Jing; Wang, Hailong; Wang, Mo; Warren, Stephen G.; Zhang, Rudong

    2014-01-01

    Light absorbing particles (LAP, e.g., black carbon, brown carbon, and dust) influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric heating by absorption of solar radiation and interactions with clouds, LAP in snow on land and ice can reduce the surface reflectance (a.k.a., surface darkening), which is likely to accelerate the snow aging process and further reduces snow albedo and increases the speed of snowpack melt. LAP in snow and ice (LAPSI) has been identified as one of major forcings affecting climate change, e.g. in the fourth and fifth assessment reports of IPCC. However, the uncertainty level in quantifying this effect remains very high. In this review paper, we document various technical methods of measuring LAPSI and review the progress made in measuring the LAPSI in Arctic, Tibetan Plateau and other mid-latitude regions. We also report the progress in modeling the mass concentrations, albedo reduction, radiative forcing, and climatic and hydrological impact of LAPSI at global and regional scales. Finally we identify some research needs for reducing the uncertainties in the impact of LAPSI on global and regional climate and the hydrological cycle.

  12. Quantifying the influence of sea ice on ocean microseism using observations from the Bering Sea, Alaska

    USGS Publications Warehouse

    Tsai, V.C.; McNamara, D.E.

    2011-01-01

    Microseism is potentially affected by all processes that alter ocean wave heights. Because strong sea ice prevents large ocean waves from forming, sea ice can therefore significantly affect microseism amplitudes. Here we show that this link between sea ice and microseism is not only a robust one but can be quantified. In particular, we show that 75-90% of the variability in microseism power in the Bering Sea can be predicted using a fairly crude model of microseism damping by sea ice. The success of this simple parameterization suggests that an even stronger link can be established between the mechanical strength of sea ice and microseism power, and that microseism can eventually be used to monitor the strength of sea ice, a quantity that is not as easily observed through other means. Copyright 2011 by the American Geophysical Union.

  13. Quantifying the influence of sea ice on ocean microseism using observations from the Bering Sea, Alaska

    USGS Publications Warehouse

    Tsai, Victor C.; McNamara, Daniel E.

    2011-01-01

    Microseism is potentially affected by all processes that alter ocean wave heights. Because strong sea ice prevents large ocean waves from forming, sea ice can therefore significantly affect microseism amplitudes. Here we show that this link between sea ice and microseism is not only a robust one but can be quantified. In particular, we show that 75–90% of the variability in microseism power in the Bering Sea can be predicted using a fairly crude model of microseism damping by sea ice. The success of this simple parameterization suggests that an even stronger link can be established between the mechanical strength of sea ice and microseism power, and that microseism can eventually be used to monitor the strength of sea ice, a quantity that is not as easily observed through other means.

  14. Micromechanics of sea ice gouge in shear zones

    NASA Astrophysics Data System (ADS)

    Sammonds, Peter; Scourfield, Sally; Lishman, Ben

    2015-04-01

    The deformation of sea ice is a key control on the Arctic Ocean dynamics. Shear displacement on all scales is an important deformation process in the sea cover. Shear deformation is a dominant mechanism from the scale of basin-scale shear lineaments, through floe-floe interaction and block sliding in ice ridges through to the micro-scale mechanics. Shear deformation will not only depend on the speed of movement of ice surfaces but also the degree that the surfaces have bonded during thermal consolidation and compaction. Recent observations made during fieldwork in the Barents Sea show that shear produces a gouge similar to a fault gouge in a shear zone in the crust. A range of sizes of gouge are exhibited. The consolidation of these fragments has a profound influence on the shear strength and the rate of the processes involved. We review experimental results in sea ice mechanics from mid-scale experiments, conducted in the Hamburg model ship ice tank, simulating sea ice floe motion and interaction and compare these with laboratory experiments on ice friction done in direct shear, and upscale to field measurement of sea ice friction and gouge deformation made during experiments off Svalbard. We find that consolidation, fragmentation and bridging play important roles in the overall dynamics and fit the model of Sammis and Ben-Zion, developed for understanding the micro-mechanics of rock fault gouge, to the sea ice problem.

  15. Arctic catastrophes in an idealized sea ice model

    NASA Astrophysics Data System (ADS)

    Eisenman, I.; Tziperman, E.; Wettlaufer, J. S.

    2006-12-01

    With recent observations of diminishing summer Arctic sea ice extent, the hypothesis of a "tipping point" in summer ice cover has been the focus of a number of studies. This view suggests that as summer Arctic sea ice cover retreats it will reach a critical point after which the ice-albedo effect will cause the summer ice cover to disappear altogether. We have examined the heuristic argument behind this hypothesis using an idealized, but observationally constrained, model of Arctic sea ice with representations of ocean mixed layer and ice thermodynamics, varying open water fraction, an energy balance atmosphere, and scalable CO2. We find that summer ice cover retreats toward an ice-free summer ocean at an accelerating rate as CO2 increases. However, with standard parameter values we find no critical CO2 concentration or "tipping point". We identify in the parameter space the bifurcation associated with multiple summer ice cover states, and we find that it occurs far from the physically realizable parameter regime. Our results suggest that the argument for a "tipping point" in summer Arctic ice cover brought on by ice albedo may not hold up when quantified; the reason is related to the fact that ice cover has only just begun to retreat at the time of maximum sunlight (June), and the ice minimum occurs in September when there is very little Arctic sunlight.

  16. Age characteristics in a multidecadal Arctic sea ice simulation

    SciTech Connect

    Hunke, Elizabeth C; Bitz, Cecllia M

    2008-01-01

    Results from adding a tracer for age of sea ice to a sophisticated sea ice model that is widely used for climate studies are presented. The consistent simulation of ice age, dynamics, and thermodynamics in the model shows explicitly that the loss of Arctic perennial ice has accelerated in the past three decades, as has been seen in satellite-derived observations. Our model shows that the September ice age average across the Northern Hemisphere varies from about 5 to 8 years, and the ice is much younger (about 2--3 years) in late winter because of the expansion of first-year ice. We find seasonal ice on average comprises about 5% of the total ice area in September, but as much as 1.34 x 10{sup 6} km{sup 2} survives in some years. Our simulated ice age in the late 1980s and early 1990s declined markedly in agreement with other studies. After this period of decline, the ice age began to recover, but in the final years of the simulation very little young ice remains after the melt season, a strong indication that the age of the pack will again decline in the future as older ice classes fail to be replenished. The Arctic ice pack has fluctuated between older and younger ice types over the past 30 years, while ice area, thickness, and volume all declined over the same period, with an apparent acceleration in the last decade.

  17. Continuum sea ice rheology determined from subcontinuum mechanics

    E-print Network

    Feltham, Daniel

    elliptic plastic yield curves, and with square, diamond and irregular, convex polygon-shaped floes water from which it forms; the formation, movement and subsequent melt of sea ice con- stitutes a substantial thermohaline forcing on the ocean. The dense, salty water expelled during sea ice formation

  18. Photo: Sinead Farrell, NOAA Measuring Arctic Sea Ice Drift Velocities

    E-print Network

    Sandwell, David T.

    weather and climate · Gain a better understanding of the global climate system and recent climate changeJulia Ruth Photo: Sinead Farrell, NOAA Measuring Arctic Sea Ice Drift Velocities from Passive is Sea Ice? SIO 236: Remote Sensing, Spring 2015 NOAA Climate.gov YouTube Channel

  19. Detecting Sea-Ice Ridges Using Satellite Imaging

    E-print Network

    Detecting Sea-Ice Ridges Using Satellite Imaging Aim: Sea ice radar backscatter model The aim satellite borne radar (SAR) data? And if so, to es- tablish the best SAR sensor parameters pressure ridge diagram.2 References: Image of satellite, Allos 2 Satellite, image -global

  20. Thermal conductivity of landfast Antarctic and Arctic sea ice

    E-print Network

    Marshall, Hans-Peter

    Thermal conductivity of landfast Antarctic and Arctic sea ice D. J. Pringle,1,2,3 H. Eicken,2 H. J; published 24 April 2007. [1] We present final results from a program to measure the thermal conductivity), Thermal conductivity of landfast Antarctic and Arctic sea ice, J. Geophys. Res., 112, C04017, doi:10

  1. Home Atmosphere Sea Ice Ocean Land Greenland Biology , J. Cappelen

    E-print Network

    Box, Jason E.

    Home Atmosphere Sea Ice Ocean Land Greenland Biology Greenland J. E. Box 1 , J. Cappelen 2 , D temperatures, ice loss by melting, and marine-terminating glacier area loss. Summer seasonal average (June melt rate since at least 1958 and an area and duration of ice sheet melting that was above any previous

  2. Sea-ice switches and abrupt climate change.

    PubMed

    Gildor, Hezi; Tziperman, Eli

    2003-09-15

    We propose that past abrupt climate changes were probably a result of rapid and extensive variations in sea-ice cover. We explain why this seems a perhaps more likely explanation than a purely thermohaline circulation mechanism. We emphasize that because of the significant influence of sea ice on the climate system, it seems that high priority should be given to developing ways for reconstructing high-resolution (in space and time) sea-ice extent for past climate-change events. If proxy data can confirm that sea ice was indeed the major player in past abrupt climate-change events, it seems less likely that such dramatic abrupt changes will occur due to global warming, when extensive sea-ice cover will not be present. PMID:14558902

  3. Observed platelet ice distributions in Antarctic sea ice: An index for ocean-ice shelf heat flux

    NASA Astrophysics Data System (ADS)

    Langhorne, P. J.; Hughes, K. G.; Gough, A. J.; Smith, I. J.; Williams, M. J. M.; Robinson, N. J.; Stevens, C. L.; Rack, W.; Price, D.; Leonard, G. H.; Mahoney, A. R.; Haas, C.; Haskell, T. G.

    2015-07-01

    Antarctic sea ice that has been affected by supercooled Ice Shelf Water (ISW) has a unique crystallographic structure and is called platelet ice. In this paper we synthesize platelet ice observations to construct a continent-wide map of the winter presence of ISW at the ocean surface. The observations demonstrate that, in some regions of coastal Antarctica, supercooled ISW drives a negative oceanic heat flux of -30 Wm-2 that persists for several months during winter, significantly affecting sea ice thickness. In other regions, particularly where the thinning of ice shelves is believed to be greatest, platelet ice is not observed. Our new data set includes the longest ice-ocean record for Antarctica, which dates back to 1902 near the McMurdo Ice Shelf. These historical data indicate that, over the past 100 years, any change in the volume of very cold surface outflow from this ice shelf is less than the uncertainties in the measurements.

  4. Biological and physical processes influencing sea ice, under-ice algae, and dimethylsulfoniopropionate during spring in the Canadian Arctic Archipelago

    NASA Astrophysics Data System (ADS)

    Galindo, V.; Levasseur, M.; Mundy, C. J.; Gosselin, M.; Tremblay, J.-É.; Scarratt, M.; Gratton, Y.; Papakiriakou, T.; Poulin, M.; Lizotte, M.

    2014-06-01

    This study presents temporal variations in concentrations of chlorophyll a (Chl a), particulate and dissolved dimethylsulfoniopropionate (DMSPp and DMSPd) in the sea ice and underlying water column in the Canadian Arctic Archipelago during the spring of 2010 and 2011. During both years, bottom ice Chl a, DMSPp and DMSPd concentrations were high (up to 1328 µg L-1, 15,082 nmol L-1, and 6110 nmol L-1, respectively) in May and decreased thereafter. The release of bottom ice algae and DMSPp in the water column was gradual in 2010 and rapid (8 days) in 2011. Bottom brine drainage during the presnowmelt period in 2010 and a rapid loss of the snow cover in 2011 coinciding with rain events explain most of the difference between the 2 years. During both years, less than 13% of the DMSPd lost from the ice was detected in the water column, suggesting a rapid microbial consumption. An under-ice diatom bloom developed in both years. In 2010, the bloom was dominated by centric diatoms while in 2011 pennates dominated, likely reflecting seeding by ice algae following the faster snowmelt progression induced by rainfall events in 2011. Both under-ice blooms were associated with high DMSPp concentrations (up to 185 nmol L-1), but pennate diatoms showed DMSPp/Chl a ratios twice higher than centrics. These results highlight the key role of snowmelt and precipitation on the temporal pattern of ice-DMSP release to the water column and on the timing, taxonomic composition, and DMSP content of phytoplankton under-ice blooms in the Arctic.

  5. Sea Ice Kinematics and Thickness from RGPS: Observations and Theory

    NASA Technical Reports Server (NTRS)

    Stern, Harry; Lindsay, Ron; Yu, Yan-Ling; Moritz, Richard; Rothrock, Drew

    2005-01-01

    The RADARSAT Geophysical Processor System (RGPS) has produced a wealth of data on Arctic sea ice motion, deformation, and thickness with broad geographical coverage and good temporal resolution. These data provide unprecedented spatial detail of the structure and evolution of the sea ice cover. The broad purpose of this study was to take advantage of the strengths of the RGPS data set to investigate sea ice kinematics and thickness, which affect the climate through their influence on ice production, ridging, and transport (i.e. mass balance); heat flux to the atmosphere; and structure of the upper ocean mixed layer. The objectives of this study were to: (1) Explain the relationship between the discontinuous motion of the ice cover and the large-scale, smooth wind field that drives the ice; (2) Characterize the sea ice deformation in the Arctic at different temporal and spatial scales, and compare it with deformation predicted by a state-of-theart ice/ocean model; and (3) Compare RGPS-derived sea ice thickness with other data, and investigate the thinning of the Arctic sea ice cover as seen in ULS data obtained by U.S. Navy submarines. We briefly review the results of our work below, separated into the topics of sea ice deformation and sea ice thickness. This is followed by a list of publications, meetings and presentations, and other activities supported under this grant. We are attaching to this report copies of all the listed publications. Finally, we would like to point out our community service to NASA through our involvement with the ASF User Working Group and the RGPS Science Working Group, as evidenced in the list of meetings and presentations below.

  6. Time-dependence of sea-ice concentration and multiyear ice fraction in the Arctic Basin

    USGS Publications Warehouse

    Gloersen, P.; Zwally, H.J.; Chang, A.T.C.; Hall, D.K.; Campbell, W.J.; Ramseier, R.O.

    1978-01-01

    The time variation of the sea-ice concentration and multiyear ice fraction within the pack ice in the Arctic Basin is examined, using microwave images of sea ice recently acquired by the Nimbus-5 spacecraft and the NASA CV-990 airborne laboratory. The images used for these studies were constructed from data acquired from the Electrically Scanned Microwave Radiometer (ESMR) which records radiation from earth and its atmosphere at a wavelength of 1.55 cm. Data are analyzed for four seasons during 1973-1975 to illustrate some basic differences in the properties of the sea ice during those times. Spacecraft data are compared with corresponding NASA CV-990 airborne laboratory data obtained over wide areas in the Arctic Basin during the Main Arctic Ice Dynamics Joint Experiment (1975) to illustrate the applicability of passive-microwave remote sensing for monitoring the time dependence of sea-ice concentration (divergence). These observations indicate significant variations in the sea-ice concentration in the spring, late fall and early winter. In addition, deep in the interior of the Arctic polar sea-ice pack, heretofore unobserved large areas, several hundred kilometers in extent, of sea-ice concentrations as low as 50% are indicated. ?? 1978 D. Reidel Publishing Company.

  7. Solar PAR and UVR modify the community composition and photosynthetic activity of sea ice algae.

    PubMed

    Enberg, Sara; Piiparinen, Jonna; Majaneva, Markus; Vähätalo, Anssi V; Autio, Riitta; Rintala, Janne-Markus

    2015-10-01

    The effects of increased photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) on species diversity, biomass and photosynthetic activity were studied in fast ice algal communities. The experimental set-up consisted of nine 1.44 m(2) squares with three treatments: untreated with natural snow cover (UNT), snow-free (PAR + UVR) and snow-free ice covered with a UV screen (PAR). The total algal biomass, dominated by diatoms and dinoflagellates, increased in all treatments during the experiment. However, the smaller biomass growth in the top 10-cm layer of the PAR + UVR treatment compared with the PAR treatment indicated the negative effect of UVR. Scrippsiella complex (mainly Scrippsiella hangoei, Biecheleria baltica and Gymnodinium corollarium) showed UV sensitivity in the top 5-cm layer, whereas Heterocapsa arctica ssp. frigida and green algae showed sensitivity to both PAR and UVR. The photosynthetic activity was highest in the top 5-cm layer of the PAR treatment, where the biomass of the pennate diatom Nitzschia frigida increased, indicating the UV sensitivity of this species. This study shows that UVR is one of the controlling factors of algal communities in Baltic Sea ice, and that increased availability of PAR together with UVR exclusion can cause changes in algal biomass, photosynthetic activity and community composition. PMID:26310455

  8. Characterizing Arctic sea ice topography using high-resolution IceBridge data

    NASA Astrophysics Data System (ADS)

    Petty, A. A.; Tsamados, M. C.; Kurtz, N. T.; Farrell, S. L.; Newman, T.; Harbeck, J. P.; Feltham, D. L.; Richter-Menge, J. A.

    2015-11-01

    We present an analysis of Arctic sea ice topography using high resolution, three-dimensional, surface elevation data from the Airborne Topographic Mapper, flown as part of NASA's Operation IceBridge mission. Surface features in the sea ice cover are detected using a newly developed surface feature picking algorithm. We derive information regarding the height, volume and geometry of surface features from 2009-2014 within the Beaufort/Chukchi and Central Arctic regions. The results are delineated by ice type to estimate the topographic variability across first-year and multi-year ice regimes. The results demonstrate that Arctic sea ice topography exhibits significant spatial variability, mainly driven by the increased surface feature height and volume (per unit area) of the multi-year ice that dominates the Central Arctic region. The multi-year ice topography exhibits greater interannual variability compared to the first-year ice regimes, which dominates the total ice topography variability across both regions. The ice topography also shows a clear coastal dependency, with the feature height and volume increasing as a function of proximity to the nearest coastline, especially north of Greenland and the Canadian Archipelago. A strong correlation between ice topography and ice thickness (from the IceBridge sea ice product) is found, using a square-root relationship. The results allude to the importance of ice deformation variability in the total sea ice mass balance, and provide crucial information regarding the tail of the ice thickness distribution across the western Arctic. Future research priorities associated with this new dataset are presented and discussed, especially in relation to calculations of atmospheric form drag.

  9. Fine-resolution simulation of surface current and sea ice in the Arctic Mediterranean Seas

    NASA Astrophysics Data System (ADS)

    Liu, Xiying; Zhang, Xuehong; Yu, Rucong; Liu, Hailong; Li, Wei

    2007-04-01

    A fine-resolution model is developed for ocean circulation simulation in the National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Chinese Academy of Sciences, and is applied to simulate surface current and sea ice variations in the Arctic Mediterranean Seas. A dynamic sea ice model in elastic-viscous-plastic rheology and a thermodynamic sea ice model are employed. A 200-year simulation is performed and a dimatological average of a 10-year period (141st 150th) is presented with focus on sea ice concentration and surface current variations in the Arctic Mediterranean Seas. The model is able to simulate well the East Greenland Current, Beaufort Gyre and the Transpolar Drift, but the simulated West Spitsbergen Current is small and weak. In the March climatology, the sea ice coverage can be simulated well except for a bit more ice in east of Spitsbergen Island. The result is also good for the September scenario except for less ice concentration east of Greenland and greater ice concentration near the ice margin. The extra ice east of Spitsbergen Island is caused by sea ice current convergence forced by atmospheric wind stress.

  10. Assimilation of sea surface temperature, sea ice concentration and sea ice drift in a model of the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Barth, Alexander; Canter, Martin; Van Schaeybroeck, Bert; Vannitsem, Stéphane; Massonnet, François; Zunz, Violette; Mathiot, Pierre; Alvera-Azcárate, Aida; Beckers, Jean-Marie

    2015-09-01

    Current ocean models have relatively large errors and biases in the Southern Ocean. The aim of this study is to provide a reanalysis from 1985 to 2006 assimilating sea surface temperature, sea ice concentration and sea ice drift. In the following it is also shown how surface winds in the Southern Ocean can be improved using sea ice drift estimated from infrared radiometers. Such satellite observations are available since the late seventies and have the potential to improve the wind forcing before more direct measurements of winds over the ocean are available using scatterometry in the late nineties. The model results are compared to the assimilated data and to independent measurements (the World Ocean Database 2009 and the mean dynamic topography based on observations). The overall improvement of the assimilation is quantified, in particular the impact of the assimilation on the representation of the polar front is discussed. Finally a method to identify model errors in the Antarctic sea ice area is proposed based on Model Output Statistics techniques using a series of potential predictors. This approach provides new directions for model improvements.

  11. Assessment of Regional Climate Model-Simulated Snow Density Over the Greenland and Antarctic Ice Sheets Using In-Situ Measurements

    NASA Astrophysics Data System (ADS)

    Alexander, P. M.; Koenig, L.; Tedesco, M.; Datta, R.; Fettweis, X.

    2014-12-01

    An accurate representation of density of snow and firn at the surface of the Greenland and Antarctic ice sheets is important for both models and measurements of ice sheet mass change, and therefore estimates of ice sheet contribution to past and future sea level rise. In particular, mass change derived from satellite and airborne snow accumulation measurements (e.g. accumulation from IceBridge, and volume changes from ICESat and Cryosat-2) rely on estimates of snow and firn density to convert measured surface elevation changes into estimates of mass change. While numerous firn densification models (FDMs) have been applied over both ice sheets, there has been little evaluation of the density simulated by regional climate models (RCMs). RCMs capture the coupling between the surface-and the atmosphere, as well as sub-surface hydrology and thermodynamics, and are used to make future projections of ice sheet mass change. Improving accuracy of simulated density is important for improved representation of RCM-simulated surface processes. Here we present an initial validation of density profiles in the Modèle Atmosphérique Régionale (MAR) RCM against in situ data from the SUMup community dataset. An analysis of initial results indicates that MAR tends underestimate surface density in the first two meters of the snowpack at the cores examined. Additionally, initialization of the MAR snowpack may lead to errors in subsurface density in some locations. These biases and errors may impact simulation of storage of meltwater within the firn and may lead to an underestimation of mass changes if simulated density is combined with remote-sensing-derived accumulation estimates.

  12. Global warming releases microplastic legacy frozen in Arctic Sea ice

    NASA Astrophysics Data System (ADS)

    Obbard, Rachel W.; Sadri, Saeed; Wong, Ying Qi; Khitun, Alexandra A.; Baker, Ian; Thompson, Richard C.

    2014-06-01

    When sea ice forms it scavenges and concentrates particulates from the water column, which then become trapped until the ice melts. In recent years, melting has led to record lows in Arctic Sea ice extent, the most recent in September 2012. Global climate models, such as that of Gregory et al. (2002), suggest that the decline in Arctic Sea ice volume (3.4% per decade) will actually exceed the decline in sea ice extent, something that Laxon et al. (2013) have shown supported by satellite data. The extent to which melting ice could release anthropogenic particulates back to the open ocean has not yet been examined. Here we show that Arctic Sea ice from remote locations contains concentrations of microplastics at least two orders of magnitude greater than those that have been previously reported in highly contaminated surface waters, such as those of the Pacific Gyre. Our findings indicate that microplastics have accumulated far from population centers and that polar sea ice represents a major historic global sink of man-made particulates. The potential for substantial quantities of legacy microplastic contamination to be released to the ocean as the ice melts therefore needs to be evaluated, as do the physical and toxicological effects of plastics on marine life.

  13. Antarctic sea ice change and variability - Physical and ecological implications

    NASA Astrophysics Data System (ADS)

    Massom, Robert A.; Stammerjohn, Sharon E.

    2010-08-01

    Although Antarctic sea ice is undergoing a slight increase in overall extent, major regional changes are occurring in its spatio-temporal characteristics (most notably in sea ice seasonality). Biologically significant aspects of Antarctic sea ice are evaluated, emphasising the importance of scale and thermodynamics versus dynamics. Changing sea ice coverage is having major direct and indirect though regionally-dependent effects on ecosystem structure and function, with the most dramatic known effects to date occurring in the West Antarctic Peninsula region. There is mounting evidence that loss of sea ice has affected multiple levels of the marine food web in a complex fashion and has triggered cascading effects. Impacts on primary production, Antarctic krill, fish, marine mammals and birds are assessed, and are both negative and positive. The review includes recent analysis of change/variability in polynyas and fast ice, and also highlights the significance of extreme events (which have paradoxical impacts). Possible future scenarios are investigated in the light of the predicted decline in sea ice by 2100 e.g. increased storminess/waviness, numbers of icebergs and snowfall. Our current lack of knowledge on many aspects of sea ice-related change and biological response is emphasised.

  14. Sea Ice Response to Atmospheric and Oceanic Forcing in the Bering Sea JINLUN ZHANG, REBECCA WOODGATE, AND RICHARD MORITZ

    E-print Network

    Zhang, Jinlun

    Sea Ice Response to Atmospheric and Oceanic Forcing in the Bering Sea JINLUN ZHANG, REBECCA March 2010) ABSTRACT A coupled sea ice­ocean model is developed to quantify the sea ice response to changes in atmospheric and oceanic forcing in the Bering Sea over the period 1970­2008. The model captures

  15. Cold air incursions, ?18O variability, and monsoon dynamics associated with snow days at Quelccaya Ice Cap, Peru

    NASA Astrophysics Data System (ADS)

    Hurley, John V.; Vuille, Mathias; Hardy, Douglas R.; Burns, Stephen J.; Thompson, Lonnie G.

    2015-08-01

    Quelccaya Ice Cap in the Andes of Peru contains an annually resolved ?18O record covering the past 1800 years; yet atmospheric dynamics associated with snow deposition and ?18O variability at this site are poorly understood. Here we make use of 10 years of snow pit and short core ?18O data and hourly snow-height measurements obtained by an automated weather station deployed at the ice cap's summit to analyze linkages between snowfall, ?18O, and the South American summer monsoon (SASM). Snow accumulation peaks in December and is negative May-September. Snow ?18O values decrease gradually through austral summer from about -17 to -24‰. Surface snow ?18O is altered after deposition during austral winter from about -24 to -15‰. More than 70% of the total snow accumulation is tied to convection along the leading edge of cold air incursions of midlatitude air advected equatorward from southern South America. Snowfall amplitude at Quelccaya Ice Cap varies systematically with regional precipitation, atmospheric dynamics, midtroposphere humidity, and water vapor ?D. Strongest snowfall gains correspond with positive precipitation anomalies over the western Amazon Basin, increased humidity, and lowered water vapor ?D values, consistent with the "amount effect." We discuss ventilation of the monsoon, modulated by midlatitude cold air advection, as potentially diagnostic of the relationship between SASM dynamics and Quelccaya snowfall. Results will serve as a basis for development of a comprehensive isotopic forward model to reconstruct past monsoon dynamics using the ice core ?18O record.

  16. Ice-atmosphere interactions during sea-ice advance and retreat in the western Antarctic Peninsula region

    E-print Network

    Ice-atmosphere interactions during sea-ice advance and retreat in the western Antarctic Peninsula June 2003; accepted 28 July 2003; published 21 October 2003. [1] The seasonal evolution of sea-ice atmospheric synoptic variability, are described for a winter period (1992) when sea-ice advance and retreat

  17. Monitoring snow melt characteristics on the Greenland ice sheet using a new MODIS land surface temperature and emissivity product (MOD21)

    NASA Astrophysics Data System (ADS)

    Hulley, G. C.; Hall, D. K.; Hook, S. J.

    2013-12-01

    Land Surface Temperature (LST) and emissivity are sensitive energy-balance parameters that control melt and energy exchange between the surface and the atmosphere. MODIS LST is currently used to monitor melt zones on glaciers and can be used for glacier or ice sheet mass balance calculations. Much attention has been paid recently to the warming of the Arctic in the context of global warming, with a focus on the Greenland ice sheet because of its importance with sea-level rise. Various researchers have shown a steady decline in the extent of the Northern Hemisphere sea ice, both the total extent and the extent of the perennial or multiyear ice. Surface melt characteristics over the Greenland ice sheet have been traditionally monitored using the MODIS LST and albedo products (e.g. MOD11 and MOD10A1). Far fewer studies have used thermal emissivity data to monitor surface melt characteristics due to the lack of suitable data. In theory, longwave emissivity combined with LST information should give a more direct measure of snow melt characteristics since the emissivity is an intrinsic property of the surface, whereas the albedo is dependent on other factors such as solar zenith angle, and shadowing effects. Currently no standard emissivity product exists that can dynamically retrieve changes in longwave emissivity consistently over long time periods. This problem has been addressed with the new MOD21 product, which uses the ASTER TES algorithm to dynamically retrieve LST and spectral emissivity (bands 29, 31, 32) at 1-km resolution. In this study we show that using a new proposed index termed the snow emissivity difference index (SEDI) derived from the MOD21 longwave emissivity product, combined with the LST, will improve our understanding of snow melt and freezeup dynamics on ice sheets such as Greenland. The results also suggest that synergistic use of both thermal-based and albedo data will help to improve our understanding of snow melt dynamics on glaciers and ice sheets, and reduce uncertainties in estimating magnitudes and trends.

  18. An overview of the studies on black carbon and mineral dust deposition in snow and ice cores in East Asia

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Xu, Baiqing; Ming, Jing

    2014-06-01

    Black carbon (BC) is the most effective insoluble light-absorbing particulate (ILAP), which can strongly absorb solar radiation at visible wavelengths. Once BC is deposited in snow via dry or wet process, even a small amount of BC could significantly decrease snow albedo, enhance absorption of solar radiation, accelerate snow melting, and cause climate feedback. BC is considered the second most important component next to CO2 in terms of global warming. Similarly, mineral dust (MD) is another type of ILAP. So far, little attention has been paid to quantitative measurements of BC and MD deposition on snow surface in the midlatitudes of East Asia, especially over northern China. In this paper, we focus on reviewing several experiments performed for collecting and measuring scavenging BC and MD in the high Asian glaciers over the mount' range (such as the Himalayas) and in seasonal snow over northern China. Results from the surveyed literature indicate that the absorption of ILAP in seasonal snow is dominated by MD in the Qilian Mount's and by local soil dust in the Inner Mongolian region close to dust sources. The detection of BC in snow and ice cores using modern techniques has a large bias and uncert'ty when the snow sample is mixed with MD. Evidence also indicates that the reduction of snow albedo by BC and MD perturbations can significantly increase the net surface solar radiation, cause surface air temperature to rise, reduce snow accumulation, and accelerate snow melting.

  19. Albedo of bare ice near the Trans-Antarctic Mountains to represent sea-glaciers on the tropical ocean of Snowball Earth

    NASA Astrophysics Data System (ADS)

    Warren, S. G.; Dadic, R.; Mullen, P.; Schneebeli, M.; Brandt, R. E.

    2012-12-01

    The albedos of snow and ice surfaces are, because of their positive feedback, crucial to the initiation, maintenance, and termination of a snowball event, as well as for determining the ice thickness on the ocean. Despite the name, Snowball Earth would not have been entirely snow-covered. As on modern Earth, evaporation would exceed precipitation over much of the tropical ocean. After a transient period with sea ice, the dominant ice type would probably be sea-glaciers flowing in from higher latitude. As they flowed equatorward into the tropical region of net sublimation, their surface snow and subsurface firn would sublimate away, exposing bare glacier ice to the atmosphere and to solar radiation. This ice would be freshwater (meteoric) ice, which originated from snow and firn, so it would contain numerous air bubbles, which determine the albedo. The modern surrogate for this type of ice (glacier ice exposed by sublimation, which has never experienced melting), are the bare-ice surfaces of the Antarctic Ice Sheet near the Trans-Antarctic Mountains. These areas have been well mapped because of their importance in the search for meteorites. A transect across an icefield can sample ice of different ages that has traveled to different depths en route to the sublimation front. On a 6-km transect from snow to ice near the Allan Hills, spectral albedo was measured and 1-m core samples were collected. This short transect is meant to represent a north-south transect across many degrees of latitude on the snowball ocean. Surfaces on the transect transitioned through the sequence: new snow - old snow - firn - young white ice - old blue ice. The transect from snow to ice showed a systematic progression of decreasing albedo at all wavelengths, as well as decreasing specific surface area (SSA; ratio of air-ice interface area to ice mass) and increasing density. The measured spectral albedos are integrated over wavelength and weighted by the spectral solar flux to obtain broadband albedos. These range from 0.8 for snow to 0.55-0.6 for blue ice, which is in the range that favors thick ice over the tropical ocean of Snowball Earth. Air bubbles in the ice, as well as cracks, are responsible for the reflection of sunlight; their contributions to SSA were determined by micro-computed tomography. Scattering by bubbles dominates; removing cracks from the radiative-transfer calculation causes only a slight reduction of albedo. Although what determines the albedo is the SSA of bubbles or snow grains, the broadband albedo also shows a systematic relation to the snow or ice density, suggesting that density might serve as a surrogate variable that will be easier to predict than SSA in an ice-sheet model, using a parameterization for firn densification.

  20. Pacific Walrus Response to Arctic Sea Ice Losses

    USGS Publications Warehouse

    Jay, Chadwick V.; Fischbach, Anthony S.

    2008-01-01

    Sea ice plays an important role in the life of the Pacific walrus (Odobenus rosmarus divergens). U.S. Geological Survey (USGS) scientists are seeking to understand how losses of sea ice during summer over important foraging grounds in the Chukchi Sea will affect walruses. USGS scientists recently modified a remotely deployed satellite radio-tag that will aid in studying walrus foraging habitats and behaviors. Information from the tags will help USGS understand how walruses are responding to their changing environment.

  1. Large sea ice outflow into the Nares Strait in 2007

    NASA Astrophysics Data System (ADS)

    Kwok, R.; Toudal Pedersen, L.; Gudmandsen, P.; Pang, S. S.

    2010-02-01

    Sea ice flux through the Nares Strait is most active during the fall and early winter, ceases in mid- to late-winter after the formation of ice arches along the strait, and re-commences after breakup in summer. In 2007, ice arches failed to form. This resulted in the highest outflow of Arctic sea ice in the 13-year record between 1997 and 2009. The 2007 area and volume outflows of 87 × 103 km2 and 254 km3 are more than twice their 13-year means. This contributes to the recent loss of the thick, multiyear Arctic sea ice and represents ˜10% of our estimates of the mean ice export at Fram Strait. Clearly, the ice arches control Arctic sea ice outflow. The duration of unobstructed flow explains more than 84% of the variance in the annual area flux. In our record, seasonal stoppages are always associated with the formation of an arch near the same location in the southern Kane Basin. Additionally, close to half the time another ice arch forms just north of Robeson Channel prior to the formation of the Kane Basin arch. Here, we examine the ice export with satellite-derived thickness data and the timing of the formation of these ice arches.

  2. Induced ice melting by the snow flea antifreeze protein from molecular dynamics simulations.

    PubMed

    Todde, Guido; Whitman, Christopher; Hovmöller, Sven; Laaksonen, Aatto

    2014-11-26

    Antifreeze proteins (AFP) allow different life forms, insects as well as fish and plants, to survive in subzero environments. AFPs prevent freezing of the physiological fluids. We have studied, through molecular dynamics simulations, the behavior of the small isoform of the AFP found in the snow flea (sfAFP), both in water and at the ice/water interface, of four different ice planes. In water at room temperature, the structure of the sfAFP is found to be slightly unstable. The loop between two polyproline II helices has large fluctuations as well as the C-terminus. Torsional angle analyses show a decrease of the polyproline II helix area in the Ramachandran plots. The protein structure instability, in any case, should not affect its antifreeze activity. At the ice/water interface the sfAFP triggers local melting of the ice surface. Bipyramidal, secondary prism, and prism ice planes melt in the presence of AFP at temperatures below the melting point of ice. Only the basal plane is found to be stable at the same temperatures, indicating an adsorption of the sfAFP on this ice plane as confirmed by experimental evidence. PMID:25353109

  3. Reconstruction of changes in the Amundsen Sea and Bellingshausen Sea sector of the West Antarctic Ice Sheet since the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Larter, Robert D.; Anderson, John B.; Graham, Alastair G. C.; Gohl, Karsten; Hillenbrand, Claus-Dieter; Jakobsson, Martin; Johnson, Joanne S.; Kuhn, Gerhard; Nitsche, Frank O.; Smith, James A.; Witus, Alexandra E.; Bentley, Michael J.; Dowdeswell, Julian A.; Ehrmann, Werner; Klages, Johann P.; Lindow, Julia; Cofaigh, Colm Ó.; Spiegel, Cornelia

    2014-09-01

    Marine and terrestrial geological and marine geophysical data that constrain deglaciation since the Last Glacial Maximum (LGM) of the sector of the West Antarctic Ice Sheet (WAIS) draining into the Amundsen Sea and Bellingshausen Sea have been collated and used as the basis for a set of time-slice reconstructions. The drainage basins in these sectors constitute a little more than one-quarter of the area of the WAIS, but account for about one-third of its surface accumulation. Their mass balance is becoming increasingly negative, and therefore they account for an even larger fraction of current WAIS discharge. If all of the ice in these sectors of the WAIS were discharged to the ocean, global sea level would rise by ca 2 m. There is compelling evidence that grounding lines of palaeo-ice streams were at, or close to, the continental shelf edge along the Amundsen Sea and Bellingshausen Sea margins during the last glacial period. However, the few cosmogenic surface exposure ages and ice core data available from the interior of West Antarctica indicate that ice surface elevations there have changed little since the LGM. In the few areas from which cosmogenic surface exposure ages have been determined near the margin of the ice sheet, they generally suggest that there has been a gradual decrease in ice surface elevation since pre-Holocene times. Radiocarbon dates from glacimarine and the earliest seasonally open marine sediments in continental shelf cores that have been interpreted as providing approximate ages for post-LGM grounding-line retreat indicate different trajectories of palaeo-ice stream recession in the Amundsen Sea and Bellingshausen Sea embayments. The areas were probably subject to similar oceanic, atmospheric and eustatic forcing, in which case the differences are probably largely a consequence of how topographic and geological factors have affected ice flow, and of topographic influences on snow accumulation and warm water inflow across the continental shelf. Pauses in ice retreat are recorded where there are “bottle necks” in cross-shelf troughs in both embayments. The highest retreat rates presently constrained by radiocarbon dates from sediment cores are found where the grounding line retreated across deep basins on the inner shelf in the Amundsen Sea, which is consistent with the marine ice sheet instability hypothesis. Deglacial ages from the Amundsen Sea Embayment (ASE) and Eltanin Bay (southern Bellingshausen Sea) indicate that the ice sheet had already retreated close to its modern limits by early Holocene time, which suggests that the rapid ice thinning, flow acceleration, and grounding line retreat observed in this sector over recent decades are unusual in the context of the past 10,000 years.

  4. Collecting, shipping, storing, and imaging snow crystals and ice grains with low-temperature scanning electron microscopy.

    PubMed

    Erbe, Eric F; Rango, Albert; Foster, James; Josberger, Edward G; Pooley, Christopher; Wergin, William P

    2003-09-01

    Methods to collect, transport, and store samples of snow and ice have been developed that enable detailed observations of these samples with a technique known as low-temperature scanning electron microscopy (LTSEM). This technique increases the resolution and ease with which samples of snow and ice can be observed, studied, and photographed. Samples are easily collected in the field and have been shipped to the electron microscopy laboratory by common air carrier from distances as far as 5,000 miles. Delicate specimens of snow crystals and ice grains survive the shipment procedures and have been stored for as long as 3 years without undergoing any structural changes. The samples are not subjected to the melting or sublimation artifacts. LTSEM allows individual crystals to be observed for several hours with no detectable changes. Furthermore, the instrument permits recording of photographs containing the parallax information necessary for three-dimensional imaging of the true shapes of snowflakes, snow crystals, snow clusters, ice grains, and interspersed air spaces. This study presents detailed descriptions of the procedures that have been used successfully in the field and the laboratory to collect, ship, store, and image snow crystals and ice grains. PMID:12938115

  5. Collecting, shipping, storing, and imaging snow crystals and ice grains with low-temperature scanning electron microscopy

    USGS Publications Warehouse

    Erbe, E.F.; Rango, A.; Foster, J.; Josberger, E.G.; Pooley, C.; Wergin, W.P.

    2003-01-01

    Methods to collect, transport, and store samples of snow and ice have been developed that enable detailed observations of these samples with a technique known as low-temperature scanning electron microscopy (LTSEM). This technique increases the resolution and ease with which samples of snow and ice can be observed, studied, and photographed. Samples are easily collected in the field and have been shipped to the electron microscopy laboratory by common air carrier from distances as far as 5,000 miles. Delicate specimens of snow crystals and ice grains survive the shipment procedures and have been stored for as long as 3 years without undergoing any structural changes. The samples are not subjected to the melting or sublimation artifacts. LTSEM allows individual crystals to be observed for several hours with no detectable changes. Furthermore, the instrument permits recording of photographs containing the parallax information necessary for three-dimensional imaging of the true shapes of snowflakes, snow crystals, snow clusters, ice grains, and interspersed air spaces. This study presents detailed descriptions of the procedures that have been used successfully in the field and the laboratory to collect, ship, store, and image snow crystals and ice grains. Published 2003 Wiley-Liss, Inc.