Sample records for sea ice snow

  1. Snow Depth on Arctic Sea Ice

    Microsoft Academic Search

    Stephen G. Warren; Ignatius G. Rigor; Norbert Untersteiner; Vladimir F. Radionov; Nikolay N. Bryazgin; Yevgeniy I. Aleksandrov; Roger Colony

    1999-01-01

    Snow depth and density were measured at Soviet drifting stations on multiyear Arctic sea ice. Measurements were made daily at fixed stakes at the weather station and once- or thrice-monthly at 10-m intervals on a line beginning about 500 m from the station buildings and extending outward an additional 500 or 1000 m. There were 31 stations, with lifetimes of

  2. Microwave Signatures of Snow on Sea Ice: Modeling

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    Accurate knowledge of snow-depth distribution over sea ice is critical for polar climate studies. Current snow-depth-over-sea-ice retrieval algorithms do not sufficiently account for variations in snow and ice physical properties that can affect the accuracy of retrievals. For this reason, airborne microwave observations were coordinated with ground-based measurements of snow depth and snow properties in the vicinity of Barrow, AK, in March 2003. In this paper, the effects of snowpack properties and ice conditions on microwave signatures are examined using detailed surface-based measurements and airborne observations in conjunction with a thermal microwave-emission model. A comparison of the Microwave Emission Model of Layered Snowpacks (MEMLS) simulations with detailed snowpack and ice data from stakes along the Elson Lagoon and the Beaufort Sea and ra- 'diometer data taken from low-level flights using a Polarimetric Scanning Radiometer (PSR-A) shows that MEMLS can be used to simulate snow on sea ice and is a useful tool for understanding the limitations of the snow-depth algorithm. Analysis of radiance data taken over the Elson Lagoon and the Beaufort Sea using MEMLS suggests that the radiometric differences between the two locations are due to the differences in sea-ice emissivity. Furthermore, measured brightness temperatures suggest that the current snow-depth retrieval algorithm is sufficient for areas of smooth first-year sea ice, whereas new algorithm coefficients are needed for rough first-year sea ice. Snowpack grain size and density remain an unresolved issue for snow-depth retrievals using passive-microwave radiances.

  3. Microwave Signatures of Snow on Sea Ice: Observations

    NASA Technical Reports Server (NTRS)

    Markus, Thorsten; Cavalieri, Donald J.; Gasiewski, Albin J.; Klein, Marian; Maslanik, James A.; Powell, Dylan C.; Stankov, B. Boba; Stroeve, Julienne C.; Sturm, Matthew

    2006-01-01

    Part of the Earth Observing System Aqua Advanced Microwave Scanning Radiometer (AMSR-E) Arctic sea ice validation campaign in March 2003 was dedicated to the validation of snow depth on sea ice and ice temperature products. The difficulty with validating these two variables is that neither can currently be measured other than in situ. For this reason, two aircraft flights on March 13 and 19,2003, were dedicated to these products, and flight lines were coordinated with in situ measurements of snow and sea ice physical properties. One flight was in the vicinity of Barrow, AK, covering Elson Lagoon and the adjacent Chukchi and Beaufort Seas. The other flight was farther north in the Beaufort Sea (about 73 N, 147.5 W) and was coordinated with a Navy ice camp. The results confirm the AMSR-E snow depth algorithm and its coefficients for first-year ice when it is relatively smooth. For rough first-year ice and for multiyear ice, there is still a relationship between the spectral gradient ratio of 19 and 37 GHz, but a different set of algorithm coefficients is necessary. Comparisons using other AMSR-E channels did not provide a clear signature of sea ice characteristics and, hence, could not provide guidance for the choice of algorithm coefficients. The limited comparison of in situ snow-ice interface and surface temperatures with 6-GHz brightness temperatures, which are used for the retrieval of ice temperature, shows that the 6-GHz temperature is correlated with the snow-ice interface temperature to only a limited extent. For strong temperature gradients within the snow layer, it is clear that the 6-GHz temperature is a weighted average of the entire snow layer.

  4. The Effect of Excess Snow on Sea Ice in a Global Ice-Ocean Prediction System

    NASA Astrophysics Data System (ADS)

    Winter, B.; Bélair, S.; Lemieux, J. F.

    2014-12-01

    Snow cover on sea ice acts as a thermal insulator, greatly reducing the upward heat flux from the ocean through the ice, specifically through thin ice. The treatment of snow in the CICE sea ice model does not include the effects of blowing snow, thereby leading to an unrealistically thick snow layer on the ice. We investigate the consequences of this excess snow for the upward heat fluxes throughout the year, and how this impacts forecast accuracy in a global ice-ocean prediction model (GIOPS). First results will be presented, and computationally efficient solutions will be discussed.

  5. 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.

  6. The Influence of Platelet Ice and Snow on Antarctic Land-fast Sea Ice

    NASA Astrophysics Data System (ADS)

    Hoppmann, M.; Nicolaus, M.

    2011-12-01

    Sea ice fastened to coasts, icebergs and ice shelves is of crucial importance for climate- and ecosystems. Near Antarctic ice shelves, this land-fast sea ice exhibits two unique characteristics that distinguish it from most other sea ice: a sub-ice layer of ice platelets and a highly stratified and thick snow cover. Ice platelets are flat, plate-like ice crystals forming and growing in a layer of super-cooled water which originates from ice shelf cavities. During growth, heat is lost to the super-cooled ocean rather than conducted to the atmosphere. The crystals accumulate beneath the solid sea-ice cover, forming a layer of loose platelets and eventually becoming incorporated into the sea-ice fabric as platelet ice. Considering the fact that the amount of platelet ice contributes between 10 and 60% to the mass of the land-fast sea ice around Antarctica, very little is known about its spatial and temporal variability. A thick and partly multi-year snow cover develops on top of the Antarctic fast ice, ultimately altering the sea-ice surface and affecting the sea-ice thermodynamics and mass balance. It typically leads to snow-ice formation, surface flooding, and the development of superimposed ice from snow melt water. In order to investigate the role of platelet ice and snow for Antarctic fast ice, we have initiated a regular observation program on the land-fast sea ice of Atka Bay as part of the international Antarctic Fast Ice Network (AFIN). We performed manual measurements of sea-ice and snow thicknesses from June to December 2010 and 2011. Additionally, a mass balance buoy and an automatic weather station were deployed in 2011 and ice cores were taken. Our measurements will reveal insight into the spatial and temporal variability of sea-ice and snow thickness distributions on Atka Bay fast ice. First results show that sea-ice thickness is lowest in the eastern part of the Bay, where a thick snow cover leads to extensive surface flooding. In the West, dynamic conditions lead to high thickness and high local variability. Ice platelets were observed regularly in the boreholes, but measurement techniques have to be improved to assess the thickness of the platelet layer.

  7. ICESat: Sea ice freeboard, snow depth, and thickness

    NASA Astrophysics Data System (ADS)

    Kwok, R.

    2007-12-01

    Total freeboard (snow and ice) and thickness of the Arctic Ocean sea ice cover are derived from ICESat data for two 35-day periods: one during the fall (Oct-Nov) of 2005 and the other during the winter (Feb-Mar) of 2006. Our freeboard retrieval approach is based on reflectivity and the expected statistics of freeboard variability from combined analysis of RADARSAT/ICESat data. Results suggest that our retrieval procedures could provide consistent freeboard estimates along 25-km segments with uncertainties of better than several centimeters. With a climatology of snow density, ECMWF snowfall is used to construct a time-varying field of snow depth for the conversion of freeboard to sea ice thickness. The derived ice thickness estimates are compared with ice draft observations from moored upward looking sonar data and the snow depth/thickness data from mass balance buoys in the Beaufort Sea. Preliminary results show that the estimated ICESat thickness estimates are within 0.5 m of the ice drafts reported by moorings. In this talk, we highlight some of the issues associated with the process of freeboard retrieval, thickness estimation, and quality assessment due to the disparity of spatial resolution between the ICESat footprint and those from in-situ measurements.

  8. 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.

  9. What forces the Redistribution of Snow over Smooth Landfast Sea Ice?

    NASA Astrophysics Data System (ADS)

    Iacozza, J.; Barber, D. G.

    2009-04-01

    An understanding of the temporal evolution of snow over sea ice at different spatial scales is critical for the improvement of snow distribution parameterization in sea ice models and for the study of physical-biological coupling. Snow depth on sea ice is primarily controlled by the interaction between surface condition (i.e. type and roughness of sea ice) and the meteorological conditions of the area. Statistical analyses of the evolution of snow distribution over smooth first-year sea ice suggest that several changes in snow distribution correspond to changes in depositional and drifting events. Changes in the probability density functions (PDFs) indicate that deeper and larger snow drifts formed after snowfall or drifting events. At the microscale, snow events caused the infilling of the valleys between snowdrifts, creating larger areas of uniform snow depth. The ability to reproduce the snow distribution over sea ice was tested using SnowModel. Results from two independent model runs suggest that the model was not able to adequately reproduce the range in the observed snow distribution. The lack of agreement may in part be due to the spatial domain of the model compared to the location of the sampling sites, as well as the use of meteorological data from land stations. Results comparing meteorological variables from land- and ice stations suggest that air temperature on land can be used as a proxy measure for that on ice, while simple associations for other meteorological variables do not exist. This is a significant limitation to the study of the evolution of snow distribution since on ice measurements are not routinely collected in the Arctic.

  10. Variability of snow and ice thermal, physical and optical properties pertinent to sea ice algae biomass during spring

    NASA Astrophysics Data System (ADS)

    Mundy, C. J.; Barber, D. G.; Michel, C.

    2005-12-01

    Changes in the thermal, physical and optical properties of the snow-sea ice system and feedbacks between various temporal and spatial scales affect accumulation of microalgae at the sea ice bottom and are the focus of this research. During the spring transition period, May 4 to June 9, 2002, we closely monitored atmospheric conditions and properties of the snow-sea ice system, including thermal, physical and optical properties of the snow cover (e.g., temperature, grain size, light attenuation), ice thickness and salinity, and biomass of bottom ice algae. Results show that snowdrift size averaged 31.2 by 10.6 m with a depth range of 2 to 45 cm. Snowpacks also varied in age, distinguished by coincident peaks of snow salinity and grain size and a lower PAR extinction coefficient. Spatial variability of the snowpack was superimposed by temporal variability associated with seasonal snow-ice melt and wind redistribution of snow. Maximum biomass of ice algae was observed under intermediate snow covers. Under thin snow covers, algae biomass declined steadily coincident with seasonal warming and desalination of the ice cover. Under thick snow covers, algae biomass was negatively correlated with snow depth. These results suggest that thin snow covers were associated with a thermal effect causing sloughing of algae, whereas under deep snow, algae were still light limited and thermally insulated from the warming atmosphere. Our results highlight the importance of snow cover history on the sea ice system operating below. Furthermore, in the context of current climate change scenarios, shifts in snow depth would result in decreases of ice algae biomass.

  11. Estimation of sea ice thickness distributions through the combination of snow depth and satellite laser altimetry data

    Microsoft Academic Search

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

    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

  12. Benefits from representing snow properties and related processes in coupled ocean-sea ice models

    NASA Astrophysics Data System (ADS)

    Lecomte, Olivier; Fichefet, Thierry; Massonnet, François; Vancoppenolle, Martin

    2015-03-01

    Several large-scale sea ice simulations are performed over the last three decades using a coupled ocean-sea ice model under the same experimental setup but partly modifying the representation of snow physics in the model. The inter-simulation spread analysis yields that the simulated multi-year ice is sensitive to such changes while the seasonal sea ice, is rather dominantly driven by the external oceanic and atmospheric forcings. In the context of a thinning Arctic sea ice cover, those findings suggest that including snow processes in large-scale sea ice models is beneficial, if not necessary, to predict the timing of the Arctic multi-year ice disappearance, whereas the operational forecasting of first-year ice extent using fully coupled models will likely require improvement to the oceanic and atmospheric components themselves.

  13. A Reanalyis of the Contribution of Meteoric Ice, Flooding and Snow Ice Formation to the Mass Balance of Antarctic Sea Ice

    Microsoft Academic Search

    T. Maksym; M. Jeffries

    2003-01-01

    Sea ice core data from five autumn to early spring cruises in the Ross, Amundsen, and Bellingshausen Seas from 1993 to 1998 are reanalyzed to determine the role of meteoric ice, flooding and snow ice formation in the mass balance of Antarctic Sea Ice. Previous analysis of crystal texture and oxygen isotope data have determined that 15% to 38% of

  14. Sea Ice Freeboards and Snow Depths in the Arctic Based on Satellite Laser and Radar Altimetry

    NASA Astrophysics Data System (ADS)

    Skourup, H.; Forsberg, R.; Hanson, S.; Hvidegaard, S. M.; Stenseng, L.

    2007-12-01

    Recent techniques make it possible to monitor the sea ice freeboards in the Arctic Ocean from satellite altimetry, and by use of models under assumption of isostatic equilibrium the freeboard can be converted into thicknesses. This is however, a crude assumption as the conversion factor depends on local sea ice and snow properties, e.g. densities and the depth of the snow cover. The main unknown factor so far is the snow depth. The laser detect the surface of the snow cover, whereas conventional radar altimetry is believed to penetrate down to the snow-ice interface, depending on the snow properties. In this study we present the methods for estimation of sea ice freeboards obtained from ICESat laser altimetry from a lowest-level technique, which on Arctic Ocean basin wide scale shows good correlation with the distribution of thick multi year sea ice extracted from QuikSCAT backscatter maps. In addition we will present the results of near coincident high-resolution airborne laser scanner measurements and radar altimetry from ENVISAT in the Fram Strait and north of Alaska to estimate the differences in freeboard heights and by that obtain an estimate of the snow depths.

  15. Impacts of Arctic sea ice and continental snow cover changes on atmospheric winter teleconnections

    NASA Astrophysics Data System (ADS)

    Handorf, Dörthe; Jaiser, Ralf; Dethloff, Klaus; Rinke, Annette; Cohen, Judah

    2015-04-01

    Extreme winters in Northern Hemisphere midlatitudes in recent years have been connected to declining Arctic sea ice and continental snow cover changes in autumn following modified planetary waves in the coupled troposphere-stratosphere system. Through analyses of reanalysis data and model simulations with a state-of-the-art atmospheric general circulation model, we investigate the mechanisms between Arctic Ocean sea ice and Northern Hemisphere land snow cover changes in autumn and atmospheric teleconnections in the following winter. The observed negative Arctic Oscillation in response to sea ice cover changes is too weakly reproduced by the model. The planetary wave train structures over the Pacific and North America regions are well simulated. The strengthening and westward shift of the Siberian high-pressure system in response to sea ice and snow cover changes is underestimated compared to ERA-Interim data due to deficits in the simulated changes in planetary wave propagation characteristics.

  16. MODIS Snow and Ice Production

    NASA Technical Reports Server (NTRS)

    Hall, Dorthoy K.; Hoser, Paul (Technical Monitor)

    2002-01-01

    Daily, global snow cover maps, and sea ice cover and sea ice surface temperature (IST) maps are derived from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS), are available at no cost through the National Snow and Ice Data Center (NSIDC). Included on this CD-ROM are samples of the MODIS snow and ice products. In addition, an animation, done by the Scientific Visualization studio at Goddard Space Flight Center, is also included.

  17. Ku-Band radar penetration into Snow over Arctic Sea Ice

    Microsoft Academic Search

    S. Hendricks; L. Stenseng; V. Helm; S. Hanson; C. Haas

    2009-01-01

    Sea ice freeboard measurements are of great interest for basin-scale ice mass balance monitoring. Typically, laser- and radar-altimeters are used for freeboard retrieval in operational systems such as aircrafts and satellites. For laser beams it can be assumed that the dominant reflector is the snow\\/air interface, whereas radar waves interact with the variable physical properties of the snow cover on

  18. Large-Scale Evaluation of Satellite-Derived Snow Depth on Arctic Sea Ice Using Icebridge Product

    NASA Astrophysics Data System (ADS)

    Brucker, L.; Markus, T.

    2012-12-01

    The thickness of the snow cover on top the sea ice is a key geophysical variable which regulates heat transfer across the ocean-sea ice-snow-atmosphere system, because of snow's high albedo and low thermal conductivity. Moreover, accurate knowledge of the distribution of snow thickness on sea ice is of critical importance to retrieve accurate sea ice thickness using spaceborne and airborne altimetery measurements. So far, only space-based microwave radiometers, such as the series of Special Sensor Microwave/Imager (SSM/I) and Advanced Microwave Scanning Radiometer for EOS (AMSR-E), provide operational large-scale snow-depth-on-sea-ice retrievals. It is therefore central to evaluate these snow-depth retrievals. Using IceBridge products, we will present the first large-scale assessment of satellite-derived snow depth on Arctic sea ice. To do so, IceBridge measurements collected during 30+ sea ice flights between 2009 and 2012 were used. Specifically, products from both the Snow Radar and the Airborne Topographic Mapper were employed. These products were gridded at 12.5 km and 25 km for comparison with the spaceborne microwave radiometer measurements, as well as the snow depth and sea ice concentration products. Between 2009 and 2011, ~3440 AMSR-E 12.5-km pixels were surveyed by Operation IceBridge in the Arctic basin. About 590 of them were covered by seasonal sea ice where satellite snow depth retrievals are available, and ~2850 pixels essentially contained multi-year ice (for which snow depth retrievals are not yet performed). Over seasonal ice, the difference between IceBridge snow-radar derived snow depth and the AMSR-E Level 3 product ranges between -6 cm and 35 cm. Locally the AMSR-E algorithm can thus significantly underestimate snow depth. Using all the data available, the mean difference, though, is 0 cm, with a standard deviation of 7 cm. However, the absolute snow depth difference reveals on average a 5-cm bias, which was as low as 3 cm during an individual 2010 cross-Arctic flight. In this presentation, we will further discuss over which sea-ice types the satellite retrievals are of good or limited accuracy when compared with the IceBridge measurements. Furthermore, investigations regarding the feasibility of monitoring snow depth on multi-year sea ice will be discussed.

  19. Peculiarities of hydrocarbon distribution in the snow-ice cover of different regions of the white sea

    NASA Astrophysics Data System (ADS)

    Nemirovskaya, I. A.

    2014-03-01

    This paper presents data on the content of hydrocarbons (HCs) in the snow-ice cover of the coastal regions of the Dvina and Kandalaksha gulfs, White Sea, in 2008-2012 in comparison with the content of organic carbon, lipids, and the suspension. The accumulation of HCs in the snow-ice cover depends on the degree of pollution of the atmosphere, formation conditions of ice, and intensity of biogeochemical processes at the ice-water boundary. Thus, the highest concentrations in the water basin of Arkhangelsk are identified in snow and in the upper part of the ice. The peculiarities of formation of the snow-ice cover in Rugozero Bay of the Kandalaksha Gulf leads to the concentration of HCs in different snow and ice layers. The decreased HC content in the snow-ice cover of the White Sea, in comparison with previous studies, is caused by recession of industrial production in recent years.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Ku-Band radar penetration into Snow over Arctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Hendricks, S.; Stenseng, L.; Helm, V.; Hanson, S.; Haas, C.

    2009-12-01

    Sea ice freeboard measurements are of great interest for basin-scale ice mass balance monitoring. Typically, laser- and radar-altimeters are used for freeboard retrieval in operational systems such as aircrafts and satellites. For laser beams it can be assumed that the dominant reflector is the snow/air interface, whereas radar waves interact with the variable physical properties of the snow cover on the Arctic sea ice. In addition, radar elevation measurements may vary for different retracker algorithms, which determine the track point of the scattered echo power distribution. Since accurate knowledge of the reflection horizon is critical for sea ice thickness retrieval, validation data is necessary to investigate the penetration of radar waves into the snow for the upcoming CryoSat-2 mission. Furthermore, the combination of both optical and RF wavelengths might be used to derive snow thickness, if radar altimeters are capable of measuring the distance to the snow-ice interface reliably. We present the results of aircraft campaigns in the Arctic with a scanning laser altimeter and the Airborne SAR/Interferometric Radar Altimeter System (ASIRAS) of the European Space Agency. The elevation observations are converted into freeboard profiles, taking the different footprints into account when comparing the two systems. Based on the probability distribution of laser and radar freeboard we discuss the specific characteristics of both systems and the apparent radar penetration over sea ice in the northern Baltic Sea, the Greenland and Lincoln Sea. The results show differences in the penetration of Ku-Band radar between regions and interannual variability. In general, snow thickness could not be derived in the Arctic, whereas the penetration behavior correlates with other (QuikScat) remote sensing products.

  5. Applications of ISES for snow, ice, and sea state

    NASA Technical Reports Server (NTRS)

    Chang, Alfred T. C.; Delnore, Victor E.

    1990-01-01

    There will be six facility instruments on the NASA NPOP-1 and NPOP-2 and additional instruments on the Japanese and European satellites. Also, there are the 24 selected NASA instruments that may be flown on one of the platforms. Many of these instruments can provide data that could be very useful for real-time data studies in the snow and ice area. Any one instrument is not addressed in particular, but emphasis is placed on what is potentially possible using the capabilities of some of these instruments.

  6. Hydrocarbons in the snow-ice cover of different areas of the White Sea

    NASA Astrophysics Data System (ADS)

    Nemirovskaya, I. A.

    2014-05-01

    The data on the content of hydrocarbons (HC) are presented and compared to the contents of organic carbon, lipids, and particulate matter in the snow-ice cover of the coastal areas of Dvina and Kandalaksha bays of the White Sea (2008-2012). The accumulation of HC in the snow-ice cover depends on the degree of atmosphere contamination, the conditions of the ice formation, and the intensity of the biogeochemical processes at the ice-water interface. Because of this, the aquatic area of Arkhangelsk is characterized by the highest HC concentrations in the snow and in the upper layer of ice. The peculiarities of the formation of the snow-ice cover in Rugozero bight of Kandalaksha Bay cause the concentrating of HC in different layers of ice. The decrease of the concentration of HC in the show-ice cover of the White Sea compared to earlier studies resulted from the recession of industrial activities during the recent years.

  7. A tentative climatology of the snow load on Arctic sea ice based on satellite

    NASA Astrophysics Data System (ADS)

    Schroeder, T. M.; Pedersen, L. T.; Tonboe, R. T.

    2007-12-01

    Having a firm grasp of the sea ice extent carries over to the understanding of poleward energy transport, atmospheric heat exchange and high-latitude ocean dynamics at large. One reason to investigate the snow load is the insulation against exchange of heat. Another, regarding the intrinsic value of remote sensing, is that snow constitutes the greatest unknown in sea ice altimetry. The properties of snow can modify how deeply into the snow-ice system the altimeter signal penetrates. While Cryosat views to the ice surface, Icesat views to the snow surface. The freeboard cannot be measured and converted to ice thickness properly without compensation for the thickness and density of the snow cover. To identify the satellite channels with most information on the scenery, we made the standard assumption that the inversion of measured brightness temperature to physical parameters is sufficiently linear to converge for Gauss-Newtonian iteration. An optimal estimation scheme has been adopted and the information content in the averaging kernel matrix scrutinized for the parameters at stake. The a priori covariance and initial guess on parameters was computed by feeding the snow-ice model Memls with ERA40 atmospheric reanalysis over a range of locations, winters, and type of ice as having grown from either scratch (first-year) or not (multiyear). Each of the currently flown passive sounders under consideration, the Advanced Microwave Scanning Radiometer (AMSR), the Advanced Microwave Sounding Unit (AMSU), and the Microwave Humidity Sounder (MHS), is modelled with a measurement error taken as the sum of sensitivity and accuracy prior to launch. Covariance between the channels has been neglected. Simulation of the actual measurement discretizes the snow pack into ten numerical layers to resolve the steep temperature gradient and applies the model Rttov to represent the air column. Snow is taken to be fresh and dry, a valid assumption until melt sets in, and the density of multi-year ice is imposed a fixed decrease above the waterline. The correlation length in ice that governs scattering shifts from water content (brine) to air bubbles after the first year. The optimal set of satellite channels has been chosen, in part, by minimizing the number of platforms involved and the jumps in frequency between them. These channels provide the basis on which we intend to retrieve a snow climatology that spans the past few years. Construction requires iteration against the assumption that either type of ice alone was covering the surface pixel and then engagement with a lookup table to meet with the brightness temperature observed. Comparison of the seasonal and regional variability is made to reanalysis and in situ measurement.

  8. Influence of projected snow and sea-ice changes on future climate in heavy snowfall region

    NASA Astrophysics Data System (ADS)

    Matsumura, S.; Sato, T.

    2011-12-01

    Snow/ice albedo and cloud feedbacks are critical for climate change projection in cryosphere regions. However, future snow and sea-ice distributions are significantly different in each GCM. Thus, surface albedo in cryosphere regions is one of the causes of the uncertainty for climate change projection. Northern Japan is one of the heaviest snowfall regions in the world. In particular, Hokkaido is bounded on the north by the Okhotsk Sea, where is the southernmost ocean in the Northern Hemisphere that is covered with sea ice during winter. Wintertime climate around Hokkaido is highly sensitive to fluctuations in snow and sea-ice. The purpose of this study is to evaluate the influence of global warming on future climate around Hokkaido, using the Pseudo-Global-Warming method (PGW) by a regional climate model. The boundary conditions of the PGW run were obtained by adding the difference between the future (2090s) and past (1990s) climates simulated by coupled general circulation model (MIROC3.2 medres), which is from the CMIP3 multi-model dataset, into the 6-hourly NCEP reanalysis (R-2) and daily OISST data in the past climate (CTL) run. The PGW experiments show that snow depth significantly decreases over mountainous areas and snow cover mainly decreases over plain areas, contributing to higher surface warming due to the decreased snow albedo. Despite the snow reductions, precipitation mainly increases over the mountainous areas because of enhanced water vapor content. However, precipitation decreases over the Japan Sea and the coastal areas, indicating the weakening of a convergent cloud band, which is formed by convergence between cold northwesteries from the Eurasian continent and anticyclonic circulation over the Okhotsk Sea. These results suggest that Okhotsk sea-ice decline may change the atmospheric circulation and the resulting effect on cloud formation, resulting in changes in winter snow or precipitation. We will also examine another CMIP3 model (MRI-CGCM2.3.2), which sensitivity of surface albedo to surface air temperature is the lowest in the CMIP3 models.

  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. Snow Radar Derived Surface Elevations and Snow Depths Multi-Year Time Series over Greenland Sea-Ice During IceBridge Campaigns

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    This paper presents estimates of snow depth over sea ice from the 2009 through 2011 NASA Operation IceBridge [1] spring campaigns over Greenland and the Arctic Ocean, derived from Kansas University's wideband Snow Radar [2] over annually repeated sea-ice transects. We compare the estimates of the top surface interface heights between NASA's Atmospheric Topographic Mapper (ATM) [3] and the Snow Radar. We follow this by comparison of multi-year snow depth records over repeated sea-ice transects to derive snow depth changes over the area. For the purpose of this paper our analysis will concentrate on flights over North/South basin transects off Greenland, which are the closest overlapping tracks over this time period. The Snow Radar backscatter returns allow for surface and interface layer types to be differentiated between snow, ice, land and water using a tracking and classification algorithm developed and discussed in the paper. The classification is possible due to different scattering properties of surfaces and volumes at the radar's operating frequencies (2-6.5 GHz), as well as the geometries in which they are viewed by the radar. These properties allow the returns to be classified by a set of features that can be used to identify the type of the surface or interfaces preset in each vertical profile. We applied a Support Vector Machine (SVM) learning algorithm [4] to the Snow Radar data to classify each detected interface into one of four types. The SVM algorithm was trained on radar echograms whose interfaces were visually classified and verified against coincident aircraft data obtained by CAMBOT [5] and DMS [6] imaging sensors as well as the scanning ATM lidar. Once the interface locations were detected for each vertical profile we derived a range to each interface that was used to estimate the heights above the WGS84 ellipsoid for direct comparisons with ATM. Snow Radar measurements were calibrated against ATM data over areas free of snow cover and over GPS land surveyed areas of Thule and Sondrestrom air bases. The radar measurements were compared against the ATM and the GPS measurements that were located in the estimated radar footprints, which resulted in an overall error of ~ 0.3 m between the radar and ATM. The agreement between ATM and GPS survey is within +/- 0.1 m. References: [1] http://www.nasa.gov/mission_pages/icebridge/ [2] 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. of Glaciology Instr. and Tech., July 23, 2012. [3] Krabill, William B. 2009 and 2011, updated current year. IceBridge ATM L1B Qfit Elevation and Return Strength. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media. [4] Chih-Chung Chang and Chih-Jen Lin. "Libsvm: a library for support vector machines", ACM Transactions on Intelligent Systems and Technology, 2:2:27:1-27:27, 2011. [5] Krabill, William B. 2009 and 2011, updated current year. IceBridge CAMBOT L1B Geolocated Images, [2009-04-25, 2011-04-15]. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media. [6] Dominguez, Roseanne. 2011, updated current year. IceBridge DMS L1B Geolocated and Orthorectified Images. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media

  11. 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.

  12. Evolution of first-year and second-year snow properties on sea ice in the Weddell Sea during spring-summer transition

    Microsoft Academic Search

    Marcel Nicolaus; Christian Haas; Sascha Willmes

    2009-01-01

    Observations of snow properties, superimposed ice, and atmospheric heat fluxes have been performed on first-year and second-year sea ice in the western Weddell Sea, Antarctica. Snow in this region is particular as it does usually survive summer ablation. Measurements were performed during Ice Station Polarstern (ISPOL), a 5-week drift station of the German icebreaker RV Polarstern. Net heat flux to

  13. Snow on sea ice: Microwave remote sensing and its impact on Antarctic sea ice

    Microsoft Academic Search

    Dylan Chaloner Powell

    2005-01-01

    The accuracy of passive-microwave snow depth retrievals is potentially subject to complex error sources. These error sources can be grouped into three categories: (a) errors due to variations in snow physical properties, (b) errors due to variations in the underlying surface, and (c) errors due to variations in the atmosphere. This study investigates the impacts of these error sources on

  14. Snow depth of the Weddell and Bellingshausen sea ice covers from IceBridge surveys in 2010 and 2011: An examination

    NASA Astrophysics Data System (ADS)

    Kwok, R.; Maksym, T.

    2014-07-01

    We examine the snow radar data from the Weddell and Bellingshausen Seas acquired by eight IceBridge (OIB) flightlines in October of 2010 and 2011. In snow depth retrieval, the sidelobes from the stronger scattering snow-ice (s-i) interfaces could be misidentified as returns from the weaker air-snow (a-s) interfaces. In this paper, we first introduce a retrieval procedure that accounts for the structure of the radar system impulse response followed by a survey of the snow depths in the Weddell and Bellingshausen Seas. Limitations and potential biases in our approach are discussed. Differences between snow depth estimates from a repeat survey of one Weddell Sea track separated by 12 days, without accounting for variability due to ice motion, is -0.7 ± 13.6 cm. Average snow depth is thicker in coastal northwestern Weddell and thins toward Cape Norvegia, a decrease of >30 cm. In the Bellingshausen, the thickest snow is found nearshore in both Octobers and is thickest next to the Abbot Ice Shelf. Snow depth is linearly related to freeboard when freeboards are low but diverge as the freeboard increases especially in the thicker/rougher ice of the western Weddell. We find correlations of 0.71-0.84 between snow depth and surface roughness suggesting preferential accumulation over deformed ice. Retrievals also seem to be related to radar backscatter through surface roughness. Snow depths reported here, generally higher than those from in situ records, suggest dissimilarities in sample populations. Implications of these differences on Antarctic sea ice thickness are discussed.

  15. National Snow and Ice Data Center (NSIDC)

    NSDL National Science Digital Library

    The National Snow and Ice Data Center (NSIDC)

    This site from NSIDC is a national information and referral center in support of polar and cryospheric research. It archives and distributes digital and analog snow and ice data and maintains information about snow cover, avalanches, glaciers, ice sheets, freshwater ice, sea ice, ground ice, permafrost, atmospheric ice, paleoglaciology, and ice cores. The site provides links to data products and services, sponsored activities, exploring the cryosphere and NSIDC history, photos, publications, and events.

  16. Title: Aerodynamic and Scalar Roughness over Snow and Sea Ice In Monin-Obukhov similarity theory, the aerodynamic roughness, z0, is the artificial height

    E-print Network

    Title: Aerodynamic and Scalar Roughness over Snow and Sea Ice Abstract: In Monin-Obukhov similarity theory, the aerodynamic roughness, z0, is the artificial height above the surface at which the wind speed the theory and measurement of the aerodynamic and scalar roughness lengths over snow and sea ice. The data

  17. The seasonal cycle of snow cover, sea ice and surface albedo

    Microsoft Academic Search

    Alan Robock

    1980-01-01

    The paper examines satellite data used to construct mean snow cover caps for the Northern Hemisphere. The zonally averaged snow cover from these maps is used to calculate the seasonal cycle of zonally averaged surface albedo. The effects of meltwater on the surface, solar zenith angle, and cloudiness are parameterized and included in the calculations of snow and ice albedo.

  18. Combination of laser and radar altimeter height measurements to estimate snow depth during the 2004 Antarctic AMSR-E Sea Ice field campaign

    Microsoft Academic Search

    Carlton J. Leuschen; Robert N. Swift; Josefino C. Comiso; R. Keith Raney; Rickey D. Chapman; William B. Krabill; John G. Sonntag

    2008-01-01

    Among the most important parameters needed to evaluate the present and future state of Antarctic sea ice cover is the ice thickness. The retrieval of ice thickness using remote sensing techniques has been hampered by the absence of a capability to remotely measure snow thickness covering the sea ice. Data sets collected with Johns Hopkins Applied Physics Laboratory's Delay-Doppler Phase

  19. An AeroCom assessment of black carbon in Arctic snow and sea ice

    NASA Astrophysics Data System (ADS)

    Jiao, C.; Flanner, M. G.; Balkanski, Y.; Bauer, S. E.; Bellouin, N.; Berntsen, T. K.; Bian, H.; Carslaw, K. S.; Chin, M.; De Luca, N.; Diehl, T.; Ghan, S. J.; Iversen, T.; Kirkevåg, A.; Koch, D.; Liu, X.; Mann, G. W.; Penner, J. E.; Pitari, G.; Schulz, M.; Seland, Ø.; Skeie, R. B.; Steenrod, S. D.; Stier, P.; Takemura, T.; Tsigaridis, K.; van Noije, T.; Yun, Y.; Zhang, K.

    2013-10-01

    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 2004-2009, 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.

  20. An AeroCom assessment of black carbon in Arctic snow and sea ice

    NASA Astrophysics Data System (ADS)

    Jiao, C.; Flanner, M. G.; Balkanski, Y.; Bauer, S. E.; Bellouin, N.; Berntsen, T. K.; Bian, H.; Carslaw, K. S.; Chin, M.; De Luca, N.; Diehl, T.; Ghan, S. J.; Iversen, T.; Kirkevåg, A.; Koch, D.; Liu, X.; Mann, G. W.; Penner, J. E.; Pitari, G.; Schulz, M.; Seland, Ø.; Skeie, R. B.; Steenrod, S. D.; Stier, P.; Takemura, T.; Tsigaridis, K.; van Noije, T.; Yun, Y.; Zhang, K.

    2014-03-01

    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-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.

  1. Optical remote sensing of snow on sea ice: Ground measurements, satellite data analysis, and radiative transfer modeling

    Microsoft Academic Search

    Xiaobing Zhou

    2002-01-01

    The successful launch of the Terra satellite on December 18, 1999 opened a new era of earth observation from space. This thesis is motivated by the need for validation and promotion of the use of snow and sea ice products derived from MODIS, one of the main sensors aboard the Terra and Aqua satellites. Three cruises were made in the

  2. National Snow and Ice Data Center

    NSDL National Science Digital Library

    Roger Barry

    2001-09-15

    NSIDC offers data and information about the cryosphere; that portion of the Earth where water is in solid form, typically snow or ice. Topics include snow, glaciers, permafrost, sea ice, news and features, and others. The State of the Cryosphere section provides an overview of the status of snow and ice as indicators of climate change. An image and photo gallery provides historic photographs and satellite imagery of cryospheric conditions in both the Arctic and Antarctica.

  3. Arctic-scale assessment of satellite passive microwave-derived snow depth on sea ice using Operation IceBridge airborne data

    NASA Astrophysics Data System (ADS)

    Brucker, Ludovic; Markus, Thorsten

    2013-06-01

    Snow depth on sea ice (SD) is a key geophysical variable, knowledge of which is critical for calculating the energy and mass balance budgets. Moreover, accurate knowledge of the SD distribution is important to retrieve sea-ice thicknesses from altimetry data. So far, only space-based microwave radiometers (e.g., Advanced Microwave Scanning Radiometer for Earth Observing System; AMSR-E) provide operational SD on seasonal sea-ice retrievals. A thorough assessment of these retrievals is needed on a large scale and on a variety of sea-ice types. Our study presents such an assessment on Arctic sea ice using NASA's airborne Operation IceBridge (OIB) SDs, retrieved from radar measurements. Between 2009 and 2011, ˜610 12.5 km satellite grid cells were covered by seasonal sea ice where both satellite SD retrievals and OIB data were available. Using all the available data, the difference between the AMSR-E product and the averaged OIB snow-radar-derived SD is 0.00±0.07 m. Satellite-derived SD was accurate in the Beaufort Sea and the Canadian Archipelago but underestimated (˜0.07 m) in the Nares Strait. The RMSE between the two products ranges between 0.03 and 0.15 m. The RMSE is less than 0.06 m over a shallow snow cover (<0.20 m), in areas where satellite-retrieved ice concentrations are higher than 90%, surface smooth, and ice thicker than ˜0.5 m. Locally the AMSR-E algorithm can significantly underestimate SD. Several regions where the retrievals were less accurate (error >0.10 m) have been identified and related to the presence of either low ice concentration or significant fraction of multiyear ice within the grid cell that has not been flagged.

  4. 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.

  5. 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.

  6. Spatially-resolved mean flow and turbulence help explain observed erosion and deposition patterns of snow over Antarctic sea ice

    NASA Astrophysics Data System (ADS)

    Trujillo, E.; Giometto, M. G.; Leonard, K. C.; Maksym, T. L.; Meneveau, C. V.; Parlange, M. B.; Lehning, M.

    2014-12-01

    Sea ice-atmosphere interactions are major drivers of patterns of sea ice drift and deformations in the Polar regions, and affect snow erosion and deposition at the surface. Here, we combine analyses of sea ice surface topography at very high-resolutions (1-10 cm), and Large Eddy Simulations (LES) to study surface drag and snow erosion and deposition patterns from process scales to floe scales (1 cm - 100 m). The snow/ice elevations were obtained using a Terrestrial Laser Scanner during the SIPEX II (Sea Ice Physics and Ecosystem eXperiment II) research voyage to East Antarctica (September-November 2012). LES are performed on a regular domain adopting a mixed pseudo-spectral/finite difference spatial discretization. A scale-dependent dynamic subgrid-scale model based on Lagrangian time averaging is adopted to determine the eddy-viscosity in the bulk of the flow. Effects of larger-scale features of the surface on wind flows (those features that can be resolved in the LES) are accounted for through an immersed boundary method. Conversely, drag forces caused by subgrid-scale features of the surface should be accounted for through a parameterization. However, the effective aerodynamic roughness parameter z0 for snow/ice is not known. Hence, a novel dynamic approach is utilized, in which z0 is determined using the constraint that the total momentum flux (drag) must be independent on grid-filter scale. We focus on three ice floe surfaces. The first of these surfaces (October 6, 2012) is used to test the performance of the model, validate the algorithm, and study the spatial distributed fields of resolved and modeled stress components. The following two surfaces, scanned at the same location before and after a snow storm event (October 20/23, 2012), are used to propose an application to study how spatially resolved mean flow and turbulence relates to observed patterns of snow erosion and deposition. We show how erosion and deposition patterns are correlated with the computed stresses, with modeled stresses having higher explanatory power. Deposition is mainly occurring in wake regions of specific ridges that strongly affect wind flow patterns. These larger ridges also lock in place elongated streaks of relatively high speeds with axes along the stream-wise direction, and which are largely responsible for the observed erosion.

  7. Remote sensing of snow and ice

    NASA Technical Reports Server (NTRS)

    Rango, A.

    1979-01-01

    This paper reviews remote sensing of snow and ice, techniques for improved monitoring, and incorporation of the new data into forecasting and management systems. The snowcover interpretation of visible and infrared data from satellites, automated digital methods, radiative transfer modeling to calculate the solar reflectance of snow, and models using snowcover input data and elevation zones for calculating snowmelt are discussed. The use of visible and near infrared techniques for inferring snow properties, microwave monitoring of snowpack characteristics, use of Landsat images for collecting glacier data, monitoring of river ice with visible imagery from NOAA satellites, use of sequential imagery for tracking ice flow movement, and microwave studies of sea ice are described. Applications of snow and ice research to commercial use are examined, and it is concluded that a major problem to be solved is characterization of snow and ice in nature, since assigning of the correct properties to a real system to be modeled has been difficult.

  8. 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

  9. Passive microwave remote sensing of seasonal snow-covered sea ice

    Microsoft Academic Search

    Alexandre Langlois; David G. Barber

    2007-01-01

    The Arctic is thought to be an area where we can expect to see the fi rst and strongest signs of global-scale climate variability and change. We have already begun to see a reduction in: (1) the aerial extent of sea ice at about 3% per decade and (2) ice thickness at about 40%. At the current rate of reduction

  10. An Assessment of the AMSR-E Snow Depth on Sea Ice Algorithm Using the March 2006 Arctic Field Campaign Aircraft Measurements

    Microsoft Academic Search

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

    2010-01-01

    The goal of the NASA March 2006 Arctic field campaign was to assess the AMSR-E snow depth on sea ice algorithm. AMSR-E snow depth is a level 3 5-day averaged product at a resolution of 12.5 km. The field campaign consisted of an initial series of coordinated surface and aircraft measurements over Elson Lagoon, Alaska and adjacent seas followed by

  11. Sea Ice

    NSDL National Science Digital Library

    In this resource, students will discover that there are notable differences between sea ice and fresh-water ice, such as density. In on segment, students learn that the first sign of freezing on the sea is an oily appearance of the water caused by the formation of needle-like crystals. The site explains the relationship between growth and the rate at which heat flows from the water and that the ice pack can alter its shape and dimension due to the movement of winds, currents, thermal expansion, and contraction of the ice. Types of ice described here include new ice, nilas, young ice, first-year ice, and old ice while the forms of ice covered include pancake ice, brash ice, ice cake, floe, and fast ice. The site also explains the meteorological and oceanographic factors that control the amount and movement of ice.

  12. 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.

  13. A vertically integrated snow/ice model over land/sea for climate models. I - Development. II - Impact on orbital change experiments

    NASA Technical Reports Server (NTRS)

    Neeman, Binyamin U.; Ohring, George; Joseph, Joachim H.

    1988-01-01

    A vertically integrated formulation (VIF) model for sea ice/snow and land snow is discussed which can simulate the nonlinear effects of heat storage and transfer through the layers of snow and ice. The VIF demonstates the accuracy of the multilayer formulation, while benefitting from the computational flexibility of linear formulations. In the second part, the model is implemented in a seasonal dynamic zonally averaged climate model. It is found that, in response to a change between extreme high and low summer insolation orbits, the winter orbital change dominates over the opposite summer change for sea ice. For snow over land the shorter but more pronounced summer orbital change is shown to dominate.

  14. Snow and ice products from Suomi NPP VIIRS

    NASA Astrophysics Data System (ADS)

    Key, Jeffrey R.; Mahoney, Robert; Liu, Yinghui; Romanov, Peter; Tschudi, Mark; Appel, Igor; Maslanik, James; Baldwin, Dan; Wang, Xuanji; Meade, Paul

    2013-12-01

    Visible Infrared Imager Radiometer Suite (VIIRS) instrument was launched in October 2011 on the satellite now known as the Suomi National Polar-orbiting Partnership. VIIRS was designed to improve upon the capabilities of the operational Advanced Very High Resolution Radiometer and provide observation continuity with NASA's Earth Observing System's Moderate Resolution Imaging Spectroradiometer (MODIS). VIIRS snow and ice products include sea ice surface temperature, sea ice concentration, sea ice characterization, a binary snow map, and fractional snow cover. Validation results with these "provisional" level maturity products show that ice surface temperature has a root-mean-square error of 0.6-1.0 K when compared to aircraft data and a similar MODIS product, the measurement accuracy and precision of ice concentration are approximately 5% and 15% when compared to passive microwave retrievals, and the accuracy of the binary snow cover (snow/no-snow) maps is generally above 90% when compared to station data. The ice surface temperature and snow cover products meet their accuracy requirements with respect to the Joint Polar Satellite System Level 1 Requirements Document. Sea Ice Characterization, which consists of two age categories, has not been observed to meet the 70% accuracy requirements of ice classification. Given their current performance, the ice surface temperature, snow cover, and sea ice concentration products should be useful for both research and operational applications, while improvements to the sea ice characterization product are needed before it can be used for these applications.

  15. Combination of laser and radar altimeter height measurements to estimate snow depth during the 2004 Antarctic AMSR-E Sea Ice field campaign

    NASA Astrophysics Data System (ADS)

    Leuschen, Carlton J.; Swift, Robert N.; Comiso, Josefino C.; Raney, R. Keith; Chapman, Rickey D.; Krabill, William B.; Sonntag, John G.

    2008-04-01

    Among the most important parameters needed to evaluate the present and future state of Antarctic sea ice cover is the ice thickness. The retrieval of ice thickness using remote sensing techniques has been hampered by the absence of a capability to remotely measure snow thickness covering the sea ice. Data sets collected with Johns Hopkins Applied Physics Laboratory's Delay-Doppler Phase Monopulse (D2P) radar and NASA's Airborne Topographic Mapper (ATM) scanning lidar during NASA's Antarctic AMSR-E Sea Ice field campaign over the Bellingshausen Sea are used to demonstrate the potential of a remote-sensing technique for retrieval of snow cover thickness from an airborne platform. The technique takes advantage of the fact that the radar is most sensitive to the snow-ice interface while the lidar responds to the highly optically reflective snow surface. The difference between the radar- and laser-determined surfaces yields an estimate of snow thickness that appears to be reasonably consistent with expected values. The technique requires careful registration of the instrument footprints. Because there was no absolute range calibration of the lidar due to predeployment scheduling difficulties, the vertical offset between the instruments was resolved by determining the difference between measurements over leads. Elsewhere over sea ice the radar-defined surface is generally below the laser-defined surface consistent with the radar defining the snow-ice interface. Over a relatively small portion of the data, we observed opposite relationship between the sensor-defined surfaces for which we discuss a plausible physical explanation.

  16. 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

  17. X-ray computed microtomography of sea ice - comment on "A review of air-ice chemical and physical interactions (AICI): liquids, quasi-liquids, and solids in snow", by Bartels-Rausch et al. (2014)

    NASA Astrophysics Data System (ADS)

    Obbard, R. W.

    2015-05-01

    This comment addresses a statement made in "A review of air-ice chemical and physical interactions (AICI): liquids, quasi-liquids, and solids in snow" by Bartels-Rausch et al. (2014). Here we rebut the assertion that X-ray computed microtomography of sea ice fails to reveal liquid brine inclusions, by discussing the phases present at the analysis temperature.

  18. All About Sea Ice

    NSDL National Science Digital Library

    Launched by the National Snow and Ice Data Center, the "All About Sea Ice" website is designed as an introduction to sea ice: what it is, how it forms, how it is studied, how it affected historical expeditions in the polar regions, and what role it plays in the global climate. The site contains over 80 pages of information on sea ice, including a glossary of sea ice terms and links to more information. The primary focus of the site is as a resource for the general public, educators and students in middle school and above. It may also be useful to researchers as a source of imagery, sample data, references, and basic information.

  19. 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.

  20. The microwave emissivity variability of snow covered first-year sea ice from late winter to early summer: a model study

    NASA Astrophysics Data System (ADS)

    Willmes, S.; Nicolaus, M.; Haas, C.

    2014-05-01

    Satellite observations of microwave brightness temperatures between 19 GHz and 85 GHz are the main data sources for operational sea-ice monitoring and retrieval of ice concentrations. However, microwave brightness temperatures depend on the emissivity of snow and ice, which is subject to pronounced seasonal variations and shows significant hemispheric contrasts. These mainly arise from differences in the rate and strength of snow metamorphism and melt. We here use the thermodynamic snow model SNTHERM forced by European Re-Analysis (ERA) interim data and the Microwave Emission Model of Layered Snowpacks (MEMLS), to calculate the sea-ice surface emissivity and to identify the contribution of regional patterns in atmospheric conditions to its variability in the Arctic and Antarctic. The computed emissivities reveal a pronounced seasonal cycle with large regional variability. The emissivity variability increases from winter to early summer and is more pronounced in the Antarctic. In the pre-melt period (January-May, July-November) the standard deviations in surface microwave emissivity due to diurnal, regional and inter-annual variability of atmospheric forcing reach up to ?? = 0.034, 0.043, and 0.097 for 19 GHz, 37 GHz and 85 GHz channels, respectively. Between 2000 and 2009, small but significant positive emissivity trends were observed in the Weddell Sea during November and December as well as in Fram Strait during February, potentially related to earlier melt onset in these regions. The obtained results contribute to a better understanding of the uncertainty and variability of sea-ice concentration and snow-depth retrievals in regions of high sea-ice concentrations.

  1. 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.

  2. ASSESSING THE UTILITY OF MODIS FOR MONITORING SNOW AND SEA ICE EXTENT

    E-print Network

    Oldenburg, Carl von Ossietzky Universität

    the low shortwave IR (SWIR) reflectance of snow which con- trasts with its high visible reflectance (3). A Normalized Difference Snow Index (NDSI) is com- puted from Band 4 (green) and Band 6 (SWIR): Band 4 - Band 6

  3. An Assessment of the AMSR-E Snow Depth on Sea Ice Algorithm Using the March 2006 Arctic Field Campaign Aircraft Measurements

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    The goal of the NASA March 2006 Arctic field campaign was to assess the AMSR-E snow depth on sea ice algorithm. AMSR-E snow depth is a level 3 5-day averaged product at a resolution of 12.5 km. The field 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 x 50 km) coordinated aircraft and AMSR-E snow depth measurements over portions of the Chukchi and Beaufort seas. The NASA 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 measure of snow depth. The paper presents the results of a comparison between the altimeter-derived snow depths and the equivalent AMSR-E snow depths using PSR-A radiances calibrated relative to AMSR-E. Data collected over refrozen leads were used to intercalibrate the ATM and D2P altimeters before calculating an altimeter snow depth. Results show that the mean difference between the equivalent AMSR-E and altimeter snow depths is -4.7 cm (AMSR-E minus altimeter) with a standard deviation of 4.4 cm. The rms difference is 6.4 cm. The overall correlation between the two snow depths is 0.70.

  4. The content and composition of organic compounds in the snow-ice cover of the White Sea

    Microsoft Academic Search

    I. A. Nemirovskaya

    2009-01-01

    This paper reports data on the concentrations of organic compounds (organic carbon, Corg; lipids; aliphatic hydrocarbons, AHCs; and polycyclic 0aromatic hydrocarbons, PAHs) in snow, ice, and subice waters from\\u000a the mouth of the Severnaya Dvina River (2005–2007) and Kandalaksha Gulf (Chupa Bay, 2004) at the end of winter. It was established\\u000a that organic compounds are accumulated in the snow and

  5. Proposed Studentship Does black carbon and humic materials in snow and ice

    E-print Network

    Royal Holloway, University of London

    to investigate whether natural oxidation of black carbon and humic materials in snow and sea-ice can lessen in snow may be causing the earlier springs and loss of sea-ice in the Arctic. The Intergovernmental Panel experiments in a new sea-ice simulator at Royal Holloway: conducting experiments on the reflectivity and light

  6. Snow and Ice Products from the Moderate Resolution Imaging Spectroradiometer

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    Snow and sea ice products, derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument, flown on the Terra and Aqua satellites, are or will be available through the National Snow and Ice Data Center Distributed Active Archive Center (DAAC). The algorithms that produce the products are automated, thus providing a consistent global data set that is suitable for climate studies. The suite of MODIS snow products begins with a 500-m resolution, 2330-km swath snow-cover map that is then projected onto a sinusoidal grid to produce daily and 8-day composite tile products. The sequence proceeds to daily and 8-day composite climate-modeling grid (CMG) products at 0.05 resolution. A daily snow albedo product will be available in early 2003 as a beta test product. The sequence of sea ice products begins with a swath product at 1-km resolution that provides sea ice extent and ice-surface temperature (IST). The sea ice swath products are then mapped onto the Lambert azimuthal equal area or EASE-Grid projection to create a daily and 8-day composite sea ice tile product, also at 1 -km resolution. Climate-Modeling Grid (CMG) sea ice products in the EASE-Grid projection at 4-km resolution are planned for early 2003.

  7. Sea ice-albedo climate feedback mechanism

    Microsoft Academic Search

    J. L. Schramm; J. A. Curry; Elizabeth E. Ebert

    1995-01-01

    The sea ice-albedo feedback mechanism over the Arctic Ocean multiyear sea ice is investigated by conducting a series of experiments using several one-dimensional models of the coupled sea ice-atmosphere system. In its simplest form, ice-albedo feedback is thought to be associated with a decrease in the areal cover of snow and ice and a corresponding increase in the surface temperature,

  8. National Snow and Ice Data Center

    NSDL National Science Digital Library

    National Snow and Ice Data Center (U.S)

    1997-01-01

    Established by the National Oceans and Atmospheric Administration (NOAA) in 1982 as an information and referral center for glaciological research, the National Snow and Ice Data Center (NSIDC) maintains data information on "snow cover and avalanches, glaciers and ice sheets, floating ice, ground ice and permafrost, atmospheric ice, paleoglaciology and ice cores." In addition to its role as an information resource, NSIDC "archives analogue and digital snow and ice data, creates and distributes data products, and maintains a large library collection in support of snow and ice research." From Global Annual Freezing and Thawing Indices to the Former Soviet Union Monthly Precipitation Archive, users may explore myriad snow and ice data. For information on current research and available data, or answers to frequently asked questions, see the NSIDC's Notes and Updates sections.

  9. Sea ice data for all: NSIDC's Arctic Sea Ice News & Analysis

    NASA Astrophysics Data System (ADS)

    Vizcarra, N.; Stroeve, J. C.; Serreze, M. C.; Scambos, T. A.; Meier, W.

    2014-12-01

    Arctic sea ice has long been recognized as a sensitive climate indicator and has undergone a dramatic decline over the past thirty years. The National Snow and Ice Data Center's Arctic Sea Ice News & Analysis blog continues to offer the public a transparent view of sea ice data and analysis. We have expanded our interactive sea ice graph to include Antarctic sea ice in response to increased attention from the public as a result of unexpected behavior of sea ice in the south. This poster explores the blog's new features and how other researchers, the media, and the public are currently using them.

  10. Sea ice-albedo climate feedback mechanism

    SciTech Connect

    Schramm, J.L.; Curry, J.A. [Univ. of Colorado, Boulder, CO (United States); Ebert, E.E. [Bureau of Meterology Research Center, Melbourne (Australia)

    1995-02-01

    The sea ice-albedo feedback mechanism over the Arctic Ocean multiyear sea ice is investigated by conducting a series of experiments using several one-dimensional models of the coupled sea ice-atmosphere system. In its simplest form, ice-albedo feedback is thought to be associated with a decrease in the areal cover of snow and ice and a corresponding increase in the surface temperature, further decreasing the area cover of snow and ice. It is shown that the sea ice-albedo feedback can operate even in multiyear pack ice, without the disappearance of this ice, associated with internal processes occurring within the multiyear ice pack (e.g., duration of the snow cover, ice thickness, ice distribution, lead fraction, and melt pond characteristics). The strength of the ice-albedo feedback mechanism is compared for several different thermodynamic sea ice models: a new model that includes ice thickness distribution., the Ebert and Curry model, the Mayjut and Untersteiner model, and the Semtner level-3 and level-0 models. The climate forcing is chosen to be a perturbation of the surface heat flux, and cloud and water vapor feedbacks are inoperative so that the effects of the sea ice-albedo feedback mechanism can be isolated. The inclusion of melt ponds significantly strengthens the ice-albedo feedback, while the ice thickness distribution decreases the strength of the modeled sea ice-albedo feedback. It is emphasized that accurately modeling present-day sea ice thickness is not adequate for a sea ice parameterization; the correct physical processes must be included so that the sea ice parameterization yields correct sensitivities to external forcing. 22 refs., 6 figs., 1 tab.

  11. National Snow and Ice Data Center: All About Snow

    NSDL National Science Digital Library

    The National Snow and Ice Data Center (NSIDC) provides innumerable educational materials about snow at this website. Students can find answers to many of their snow questions in the Q & A link. The site features remarkable pictures of blizzards and snow. Users can find an enlightening account about how early settlers dealt with snow in the Midwest and Northeast United States. The Avalanche Awareness link addresses common concerns about the causes, dangers, anatomy, and locations of avalanches. The website also offers numerous links to educational, data collections, and snow science sites.

  12. Sea Ice, an Antarctic Habitat

    NSDL National Science Digital Library

    A 'click-and-learn' sub site hosted by the Alfred Wegener Institute Foundation for Polar and Marine Research (AWI), this is a succinct, educational tour of sea-ice and its associated ecological communities. Short synopses introduce the dynamics of sea-ice formation, the microstructure of sea-ice (including crystal structure, brine channels, and ice algae), the effects of ice melt on resident organisms, the logistics of sea-ice research, and _land fast-ice_ and platelet ice habitats. Introductions also exist for the following organisms: krill; whales (i.e., Orcas, southern bottlenosesd dolphins, minke whales); sea birds (i.e., skuas and snow petrals), penguins (i.e., emperor, adelie, and chinstraps), and seals (i.e., weddell, crabeater, leopard, and ross.) Enlargeable thumbnail images accompany the habitat and inhabitant descriptions. Further investigations (at an accelerated level) are prompted with the inclusion of bibliographic references and scientific research presentations (in PDF format) on fast-ice and platelet ice, as well as links to the main site for the AWI.

  13. Sea ice terminology

    SciTech Connect

    Not Available

    1980-09-01

    A group of definitions of terms related to sea ice is presented, as well as a graphic representation of late winter ice zonation of the Beaufort Sea Coast. Terms included in the definition list are belt, bergy bit, bight, brash ice, calving, close pack ice, compacting, compact pack ice, concentration, consolidated pack ice, crack, diffuse ice edge, fast ice, fast-ice boundary, fast-ice edge, first-year ice, flaw, flaw lead, floe, flooded ice, fractured, fractured zone, fracturing, glacier, grey ice, grey-white ice, growler, hummock, iceberg, iceberg tongue, ice blink, ice boundary, ice cake, ice edge, ice foot, ice free, ice island, ice shelf, large fracture, lead, medium fracture, multiyear ice, nilas, old ice, open pack ice, open water, pack ice, polar ice, polynya, puddle, rafted ice, rafting, ram, ridge, rotten ice, second-year ice, shearing, shore lead, shore polynya, small fracture, strip, tabular berg, thaw holes, very close pack ice, very open pack ice, water sky, young coastal ice, and young ice.

  14. 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.

  15. Sensitivity of a global sea ice model to the treatment of ice thermodynamics and dynamics

    Microsoft Academic Search

    T. Fichefet; M. A. Morales Maqueda

    1997-01-01

    The sensitivity of a global thermodynamic-dynamic sea ice model coupled to a one-dimensional upper ocean model to degradations of the model physics is investigated. The thermodynamic component of the sea ice model takes into consideration the presence of snow on top of sea ice, the storage of sensible and latent heat inside the snow-ice system, the influence of the subgrid-scale

  16. Oxygen isotope composition of water and snow-ice cover of isolated lakes at various stages of separation from the White Sea

    NASA Astrophysics Data System (ADS)

    Lisitzin, A. P.; Vasil'chuk, Yu. K.; Shevchenko, V. P.; Budantseva, N. A.; Krasnova, E. D.; Pantyulin, A. N.; Filippov, A. S.; Chizhova, Ju. N.

    2013-04-01

    This study aimed to analyze the oxygen isotope composition of water, ice, and snow in water bodies isolated from the White Sea and to identify the structural peculiarities of these pools during the winter period. The studies were performed during early spring in Kandalaksha Bay of the White Sea, in Velikaya Salma Strait and in Rugoserskaya Inlet. The studied water bodies differ in their degree of isolation from the sea. In particular, Ermolinskaya Inlet has normal water exchange with the sea; the Lake on Zelenyi Cape represents the first stage of isolation; i. e., it has permanent water exchange with the sea by the tide. Kislo-Sladkoe Lake receives sea water from time to time. Trekhtsvetnoe Lake is totally isolated from the sea and is a typical meromictic lake. Finally, Nizhnee Ershovskoe Lake exhibits some features of a saline water body. The oxygen isotope profile of the water column in Trekhtsvetnoe Lake allows defining three layers; this lake may be called typically meromictic. The oxygen isotope profile of the water column in Kislo-Sladkoe Lake is even from the surface to the bottom. The variability of ?18O is minor in Lake on Zelenyi Cape. A surface layer (0-1 m) exists in Nizhnee Ershovskoe Lake, and the oxygen isotope variability is well pronounced. Deeper, where the freshwater dominates, the values of ?18Îvary insignificantly disregarding the water depth and temperature. This fresh water lake is not affected by the seawater and is not stratified according to the isotope profile. It is found that applying the values of ?18Î and profiles of temperature and salinity may appear as an effective method in defining the water sources feeding the water bodies isolated from the sea environment.

  17. 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 ...

  18. Reproduction of the large-scale state of water and sea ice in the Arctic Ocean from 1948 to 2002: Part II. The state of ice and snow cover

    NASA Astrophysics Data System (ADS)

    Yakovlev, N. G.

    2009-08-01

    This paper presents the results of reconstructing the state of ice and snow covers on the Arctic Ocean from 1948 to 2002 obtained with a couplod model of ocean circulation and sea-ice evolution. The area of the North Atlantic and Arctic Ocean north of 65° N, excluding Hudson Bay, is considered. The monthly mean ice areas and extents are analyzed. The trends of these areas are calculated separately for the periods of 1970-1979, 1979-1990, and 1990-2002. A systematic slight underestimation by the model is observed for the ice extent. This error is estimated to fit the error of 100 km in determining the position of the ice edge (i.e., close to the model resolution). In summer the model fails to reproduce many observed polynias: by observational data, the ice concentration in the central part of the Arctic Ocean constitutes around 0.8, while the model yields around 0.99. The average trend for the area of ice propagation in 1960-2002 is 13931 km2/year (or approximately 2% per decade); the trend of the ice area is 17643 km2/year (or approximately 3% per decade). This is almost three times lower than satellite data. The calculated data for ice thickness in the late winter varies from 3.5 to 4.8 m, with a clear indication of periods of thick ice (the 1960s-1970s) and relatively thin ice (the 1980s); 1995 is the starting point for quick ice-area reduction. The maximum ice accumulation is in 1977 and 1988; here, the average trend is negative: -121 km3/year (or approximately 5.5% per decade). In 1996-2002, the average change in the ice thickness constituted +1.7 cm/year. This speaks to the relatively fast disappearance of thin-ice fractions. This model also slightly underestimates the snow mass with a trend of -2.5 km3/year (almost 0.35 mm of snow per year or 0.1 mm of liquid water per year). An analysis of the monthly mean ice-drift velocity indicates the good quality of the model. Data on the average drift velocity and the results of comparisons between the calculated and satellite data for individual months are presented. A comparison with observational data from 1990-1996 in the Fram Strait shows that the model yields 3.28 m for the average ice thickness against the observed value of approximately 3.26 m. For the same period, the model yields a monthly mean transport of 291.29 km3 as compared to the observed value of 237.17 km3. A comparison between the measured and calculated drift velocities in the Fram Strait indicates that the model value is around 9.78 cm/s, which is comparable to the measured value of 10.2 cm/s. The existing problems with describing the ice redistribution by thickness gradations are illustrated by comparing data on ice thickness in the Fram Strait.

  19. Arctic sea ice minimum extent

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-10-01

    The extent of Arctic sea ice dropped to 3.41 million square kilometers on 16 September, 760,000 square kilometers below the minimum ice extent in 2007, which had been the low mark since the satellite record began in 1979, the National Snow and Ice Data Center (NSIDC) announced. Overall ice extent is 50% below where it was in the 1970s, NSIDC research scientist Walt Meier said during a 19 September briefing. He added that there is also a decrease in ice thickness. Meier said that sea ice varies from year to year with lots of ups and downs. “We wouldn't expect it to keep going down, straight off the map so to speak,” he said. “Typically after a record low, we've seen it rebound.” Meier added that the general long-term trend is for the Arctic to continue to become generally ice free. He said it is difficult to know how long it will take for that condition to be reached; because of strong variations, Arctic sea ice extent could plateau for some time.

  20. A model of the threedimensional evolution of Arctic melt ponds on firstyear and multiyear sea ice

    E-print Network

    Feltham, Daniel

    A model of the threedimensional evolution of Arctic melt ponds on firstyear and multiyear sea ice F ice. In the summer the upper layers of sea ice and snow melts producing meltwater that accumulates in Arctic melt ponds on the surface of sea ice. An accurate estimate of the fraction of the sea ice surface

  1. Bacterial diversity in snow on North Pole ice floes.

    PubMed

    Hauptmann, Aviaja L; Stibal, Marek; Bælum, Jacob; Sicheritz-Pontén, Thomas; Brunak, Søren; Bowman, Jeff S; Hansen, Lars H; Jacobsen, Carsten S; Blom, Nikolaj

    2014-11-01

    The microbial abundance and diversity in snow on ice floes at three sites near the North Pole was assessed using quantitative PCR and 454 pyrosequencing. Abundance of 16S rRNA genes in the samples ranged between 43 and 248 gene copies per millilitre of melted snow. A total of 291,331 sequences were obtained through 454 pyrosequencing of 16S rRNA genes, resulting in 984 OTUs at 97 % identity. Two sites were dominated by Cyanobacteria (72 and 61 %, respectively), including chloroplasts. The third site differed by consisting of 95 % Proteobacteria. Principal component analysis showed that the three sites clustered together when compared to the underlying environments of sea ice and ocean water. The Shannon indices ranged from 2.226 to 3.758, and the Chao1 indices showed species richness between 293 and 353 for the three samples. The relatively low abundances and diversity found in the samples indicate a lower rate of microbial input to this snow habitat compared to snow in the proximity of terrestrial and anthropogenic sources of microorganisms. The differences in species composition and diversity between the sites show that apparently similar snow habitats contain a large variation in biodiversity, although the differences were smaller than the differences to the underlying environment. The results support the idea that a globally distributed community exists in snow and that the global snow community can in part be attributed to microbial input from the atmosphere. PMID:24951969

  2. Snow is a Form of Ice

    NSDL National Science Digital Library

    This is a lesson about condensation, snow and snowflakes. Learners will investigate how water and ice exist in the atmosphere as they study water vapor condensing, find that clouds are made of tiny droplets of water, and notice that snow forms in clouds. Activities include demonstrations by the teacher, small group miming, speaking, drawing, and/or writing. In addition to commonly found classroom materials, dry ice, an aquarium or terrarium container, magnifying glass are needed. This is lesson 6 of 12 in the unit, Exploring Ice in the Solar System.

  3. 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.

  4. Correlation function studies for snow and ice

    NASA Technical Reports Server (NTRS)

    Vallese, F.; Kong, J. A.

    1981-01-01

    The random medium model is used to characterize snow and ice fields in the interpretation of active and passive microwave remote sensing data. A correlation function is used to describe the random permittivity fluctuations with the associated mean and variance and correlation lengths; and several samples are investigated to determine typical correlation functions for snow and ice. It is shown that correlation functions are extracted directly from appropriate ground truth data, and an exponential correlation function is observed for snow and ice with lengths corresponding to the actual size of ice particles or air bubbles. Thus, given that a medium has spatially stationary statistics and a small medium, the random medium model can interpret remote sensing data where theoretical parameters correspond to actual physical parameters of the terrain.

  5. Sea ice in the China Sea

    SciTech Connect

    Deng Shuqi [National Research Center for Marine Environmental Forecasts, Beijing (China)

    1993-12-31

    In every winter, sea ice occurring in Bohai Sea and the North Yellow Sea is the first-year ice which is going through generating, developing and thawing processes. Therefore, it is necessary to spatially and temporally describe ice period, freezing range, thickness variations and general motion of sea ice. The purpose of this paper is to provide initial general situation and features of sea ice for forecasting and researching sea ice.

  6. Sea ice pCO2 dynamics and air-ice CO2 fluxes during the Sea Ice Mass Balance in the Antarctic (SIMBA) experiment - Bellingshausen Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Geilfus, N.-X.; Tison, J.-L.; Ackley, S. F.; Galley, R. J.; Rysgaard, S.; Miller, L. A.; Delille, B.

    2014-12-01

    Temporal evolution of pCO2 profiles in sea ice in the Bellingshausen Sea, Antarctica, in October 2007 shows physical and thermodynamic processes controls the CO2 system in the ice. During the survey, cyclical warming and cooling strongly influenced the physical, chemical, and thermodynamic properties of the ice cover. Two sampling sites with contrasting characteristics of ice and snow thickness were sampled: one had little snow accumulation (from 8 to 25 cm) and larger temperature and salinity variations than the second site, where the snow cover was up to 38 cm thick and therefore better insulated the underlying sea ice. We show that each cooling/warming event was associated with an increase/decrease in the brine salinity, total alkalinity (TA), total dissolved inorganic carbon (TCO2), and in situ brine and bulk ice CO2 partial pressures (pCO2). Thicker snow covers reduced the amplitude of these changes: snow cover influences the sea ice carbonate system by modulating the temperature and therefore the salinity of the sea ice cover. Results indicate that pCO2 was undersaturated with respect to the atmosphere both in the in situ bulk ice (from 10 to 193 ?atm) and brine (from 65 to 293 ?atm), causing the sea ice to act as a sink for atmospheric CO2 (up to 2.9 mmol m-2 d-1), despite supersaturation of the underlying seawater (up to 462 ?atm).

  7. 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.

  8. Antarctica: Sea Ice

    NSDL National Science Digital Library

    This video segment, adapted from a NOVA broadcast, shows how sea ice forms in the Southern Ocean around Antarctica and how its seasonal fluctuation dramatically changes the continent. The segment, two minutes thirty-five seconds in length, includes rare footage of the destruction of the British ship 'Endurance', trapped and crushed by sea ice in 1914.

  9. Sea ice: Antarctic aspects

    Microsoft Academic Search

    P. SCHWERDTFEGER

    The relevance and limitations of theoretical and laboratory investiga- tions of sea ice to the Antarctic is discussed. Because of the complex thermal and mechanical perturbations suffered by sea ice under such oceanic conditions, analogue computations are suggested as being amongst the most promising methods of analysis. In the light of basic heat economy determinations, it is suggested that the

  10. Monitoring Snow on ice as Critical Habitat for Ringed Seals

    NASA Astrophysics Data System (ADS)

    Kelly, B. P.; Moran, J.; Douglas, D. C.; Nghiem, S. V.

    2007-12-01

    Ringed seals are the primary prey of polar bears, and they are found in all seasonally ice covered seas of the northern hemisphere as well as in several freshwater lakes. The presence of snow covered sea ice is essential for successful ringed seal reproduction. Ringed seals abrade holes in the ice allowing them to surface and breathe under the snow cover. Where snow accumulates to sufficient depths, ringed seals excavate subnivean lairs above breathing holes. They rest, give birth, and nurse their young in those lairs. Temperatures within the lairs remain within a few degrees of freezing, well within the zone of thermal neutrality for newborn ringed seals, even at ambient temperatures of -30° C. High rates of seal mortality have been recorded when early snow melt caused lairs to collapse exposing newborn seals to predators and to subsequent extreme cold events. As melt onset dates come earlier in the Arctic Ocean, ringed seal populations (and the polar bears that depend upon them) will be increasingly challenged. We determined dates of lair abandonment by ringed seals fitted with radio transmitters in the Beaufort Sea (n = 60). We compared abandonment dates to melt onset dates measured in the field, as well as estimated dates derived from active (Ku-band backscatter) and passive (SSM/I) microwave satellite imagery. Date of snow melt significantly improved models of environmental influences on the timing of lair abandonment. We used an algorithm based on multi-channel means and variances of passive microwave data to detect melt onset dates. Those melt onset dates predicted the date of lair abandonment ± 3 days (r 2 = 0.982, p = 0.001). The predictive power of passive microwave proxies combined with their historical record suggest they could serve to monitor critical changes to ringed seal habitat.

  11. Airborne Measurement of Sea-Ice Thickness

    NASA Astrophysics Data System (ADS)

    Gardner, Joan; Brozena, John

    2010-05-01

    The Naval Research Laboratory (NRL) is planning a major program of measurement and modeling of sea-ice thickness in the Arctic. The program will include in-situ, airborne and satellite measurements as well as development of coupled models of ocean, atmosphere and sea-ice. The authors' primary responsibility in this program will be the airborne measurement segment of the program utilizing the freeboard method for estimation of ice thickness (e.g. Hvidegaard and Forsberg, 2002). Essentially, the in-situ measurements of ice and snow thickness will be used to cal/val the airborne methodology, which will then be used to cal/val techniques of snow and ice-thickness extraction from satellite measurements. For the airborne program we plan to fly 10 and 18 GHz short-pulse (~3nsec) radar altimeters and a scanning LiDAR altimeter as well as optical or thermal camera systems. The goal is measurement of free-board at leads in the ice, and snow-thickness by the differential penetration of the three altimeter systems to estimate ice thickness. All altimeters will have full wave-form recording for the analysis of mixed and spread returns. The optical/thermal instruments will be used to help differentiate leads from the ice. We plan to coordinate the NRL airborne field program with Navy ICEX submarine and ice-island programs as well as other opportunities for ground-truth and airborne programs of NASA (ICEBRIDGE) and ESA (CRYOSAT-2).

  12. Soot climate forcing via snow and ice albedos

    NASA Astrophysics Data System (ADS)

    Hansen, James; Nazarenko, Larissa

    2004-01-01

    Plausible estimates for the effect of soot on snow and ice albedos (1.5% in the Arctic and 3% in Northern Hemisphere land areas) yield a climate forcing of +0.3 W/m2 in the Northern Hemisphere. The "efficacy" of this forcing is 2, i.e., for a given forcing it is twice as effective as CO2 in altering global surface air temperature. This indirect soot forcing may have contributed to global warming of the past century, including the trend toward early springs in the Northern Hemisphere, thinning Arctic sea ice, and melting land ice and permafrost. If, as we suggest, melting ice and sea level rise define the level of dangerous anthropogenic interference with the climate system, then reducing soot emissions, thus restoring snow albedos to pristine high values, would have the double benefit of reducing global warming and raising the global temperature level at which dangerous anthropogenic interference occurs. However, soot contributions to climate change do not alter the conclusion that anthropogenic greenhouse gases have been the main cause of recent global warming and will be the predominant climate forcing in the future. aerosols | air pollution | climate change | sea level

  13. Trend analysis of Arctic sea ice extent

    NASA Astrophysics Data System (ADS)

    Silva, M. E.; Barbosa, S. M.; Antunes, Luís; Rocha, Conceição

    2009-04-01

    The extent of Arctic sea ice is a fundamental parameter of Arctic climate variability. In the context of climate change, the area covered by ice in the Arctic is a particularly useful indicator of recent changes in the Arctic environment. Climate models are in near universal agreement that Arctic sea ice extent will decline through the 21st century as a consequence of global warming and many studies predict a ice free Arctic as soon as 2012. Time series of satellite passive microwave observations allow to assess the temporal changes in the extent of Arctic sea ice. Much of the analysis of the ice extent time series, as in most climate studies from observational data, have been focussed on the computation of deterministic linear trends by ordinary least squares. However, many different processes, including deterministic, unit root and long-range dependent processes can engender trend like features in a time series. Several parametric tests have been developed, mainly in econometrics, to discriminate between stationarity (no trend), deterministic trend and stochastic trends. Here, these tests are applied in the trend analysis of the sea ice extent time series available at National Snow and Ice Data Center. The parametric stationary tests, Augmented Dickey-Fuller (ADF), Phillips-Perron (PP) and the KPSS, do not support an overall deterministic trend in the time series of Arctic sea ice extent. Therefore, alternative parametrizations such as long-range dependence should be considered for characterising long-term Arctic sea ice variability.

  14. Tortuosity of the Antarctic Sea Ice over the Weddell Sea

    NASA Astrophysics Data System (ADS)

    Beard, J.; Heinrichs, J. F.

    2011-12-01

    The objective of the research was to mathematically characterize the edge of the Antarctic sea ice in the Weddell Sea. Because the sea ice may reflect processes involved in the atmosphere and ocean near the ice edge, it may suggest broader changes on the ice. The chosen method was to compare the tortuosity of the edge over time and across seasons. Because the sea ice may reflect processes involved in the atmosphere and ocean near the ice edge, it may suggest broader changes on the ice. Throughout the research, the shapefiles for the Antarctic sea ice were collected from the National Snow and Ice Data Center website and the coordinates were extracted using an add-in for the MapWindow GIS. These points were then put into Excel separated by year and then the distance factor (an approximation to the tortuosity) was calculated and compared by month over time. Preliminary data has shown that the closer to the winter months, the higher the tortuosity. Statistical analysis has shown that there is no clear relationship between tortuosity and the area of the sea ice, and the tortuosity exhibits a weak negative trend over the past 32 years.

  15. HAS ARCTIC SEA ICE RAPIDLY THINNED?

    Microsoft Academic Search

    Greg Holloway; Tessa Sou

    2001-01-01

    ABSTRACT Reports based on submarine,sonar data have suggested Arctic sea ice has thinned nearly by half in recent decades. Such rapid thinning is a concern for detection of global change and for Arctic regional impacts. Including atmospheric time series, ocean currents and river runoff into an ocean?ice?snow model show that the inferred rapid thinning was unlikely. The problem,stems from undersampling.

  16. The role of sea ice in structuring Antarctic ecosystems

    Microsoft Academic Search

    Hajo Eicken

    1992-01-01

    This paper focusses on the links between growth, persistence and decay of sea ice and the structure of Antarctic marine ecosystems on different spatial and temporal scales. Sea-ice growth may divide an oceanic ecosystem into two dissimilar compartments: (1) the water column, with primary production controlled by the reduction of irradiative fluxes due to the snow-laden sea-ice cover and thermo-haline

  17. Soot climate forcing via snow and ice albedos.

    PubMed

    Hansen, James; Nazarenko, Larissa

    2004-01-13

    Plausible estimates for the effect of soot on snow and ice albedos (1.5% in the Arctic and 3% in Northern Hemisphere land areas) yield a climate forcing of +0.3 W/m(2) in the Northern Hemisphere. The "efficacy" of this forcing is approximately 2, i.e., for a given forcing it is twice as effective as CO(2) in altering global surface air temperature. This indirect soot forcing may have contributed to global warming of the past century, including the trend toward early springs in the Northern Hemisphere, thinning Arctic sea ice, and melting land ice and permafrost. If, as we suggest, melting ice and sea level rise define the level of dangerous anthropogenic interference with the climate system, then reducing soot emissions, thus restoring snow albedos to pristine high values, would have the double benefit of reducing global warming and raising the global temperature level at which dangerous anthropogenic interference occurs. However, soot contributions to climate change do not alter the conclusion that anthropogenic greenhouse gases have been the main cause of recent global warming and will be the predominant climate forcing in the future. PMID:14699053

  18. Soot climate forcing via snow and ice albedos

    PubMed Central

    Hansen, James; Nazarenko, Larissa

    2004-01-01

    Plausible estimates for the effect of soot on snow and ice albedos (1.5% in the Arctic and 3% in Northern Hemisphere land areas) yield a climate forcing of +0.3 W/m2 in the Northern Hemisphere. The “efficacy” of this forcing is ?2, i.e., for a given forcing it is twice as effective as CO2 in altering global surface air temperature. This indirect soot forcing may have contributed to global warming of the past century, including the trend toward early springs in the Northern Hemisphere, thinning Arctic sea ice, and melting land ice and permafrost. If, as we suggest, melting ice and sea level rise define the level of dangerous anthropogenic interference with the climate system, then reducing soot emissions, thus restoring snow albedos to pristine high values, would have the double benefit of reducing global warming and raising the global temperature level at which dangerous anthropogenic interference occurs. However, soot contributions to climate change do not alter the conclusion that anthropogenic greenhouse gases have been the main cause of recent global warming and will be the predominant climate forcing in the future. PMID:14699053

  19. Growth, properties and relation to radar backscatter coefficient of sea ice in Lützow-Holm Bay, Antarctica

    Microsoft Academic Search

    Toshiyuki Kawamura; Hiroyuki Wakabayashi; Shuki Ushio

    2006-01-01

    Based on studies in the Antarctic Oceans, the contribution of the snow cover to sea-ice growth has become of major interest. Snow can result in upward ice growth in contrast with ordinary downward congelation growth at the bottom. A sea-ice study was conducted to verify the upward ice growth found in a previous study and to investigate the relation between

  20. 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.

  1. Arctic Sea Ice

    NSDL National Science Digital Library

    2012-06-26

    In this activity, learners explore how the area of Arctic sea ice has changed over recent years. First, learners graph the area of Arctic sea ice over time from 1979 to 2007. Then, learners use this information to extrapolate what the area will be in 2018 and graph their predictions. In part two of the activity, learners make a flip book to simulate the sea changes they just graphed. This resource includes background information related to the Northwest Passage and questions for learners to answer after completing this activity.

  2. Sea Ice 1987 - 2012

    NSDL National Science Digital Library

    This site features a video that illustrates both seasonal patterns and long-term changes in sea ice distribution across the Arctic Ocean. It draws data from two satellite instruments that measure emitted microwave radiation, which helps distinguish open ocean from ice. It shows that during the winter months, a layer of ice forms across vast expanses of the Arctic Ocean and each summer, more than half of that ice vanishes. Students discover that this natural cycle of freezing and thawing is influenced both by seasonal temperature variations and long-term climate change and that scientists are using satellite images to measure the distribution of Arctic sea ice in order to gain a better understanding of how it is linked to Earth's climate system.

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

    Microsoft Academic Search

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

    2010-01-01

    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.

  4. Iodine emissions from the sea ice of the Weddell Sea

    NASA Astrophysics Data System (ADS)

    Atkinson, H. M.; Huang, R.-J.; Chance, R.; Roscoe, H. K.; Hughes, C.; Davison, B.; Schönhardt, A.; Mahajan, A. S.; Saiz-Lopez, A.; Hoffmann, T.; Liss, P. S.

    2012-05-01

    Iodine compounds were measured above, below and within the sea ice of the Weddell Sea during a cruise in 2009, to elucidate the mechanism of local enhancement and volatilisation of iodine. I2 mixing ratios of up to 12.4 pptv were measured 10 m above the sea ice, and up to 31 pptv was observed above surface snow on the nearby Brunt Ice Shelf - large amounts. Atmospheric IO of up to 7 pptv was measured from the ship, and the average sum of HOI and ICl was 1.9 pptv. These measurements confirm the Weddell Sea as an iodine hotspot. Average atmospheric concentrations of CH3I, C2H5I, CH2ICl, 2-C3H7I, CH2IBr and 1-C3H7I were each 0.2 pptv or less. On the Brunt Ice Shelf, enhanced concentrations of CH3I and C2H5I (up to 0.5 and 1 pptv, respectively) were observed in firn air, with a diurnal profile that suggests the snow may be a source. In the sea ice brine, iodocarbons concentrations were over 10 times those of the sea water below. The sum of iodide + iodate was depleted in sea ice samples, suggesting some missing iodine chemistry. Flux calculations suggest I2 dominates the iodine atom flux to the atmosphere, but models cannot reconcile the observations and suggest either a missing iodine source or other deficiencies in our understanding of iodine chemistry. The observation of new particle formation, consistent with the model predictions, strongly suggests an iodine source. This combined study of iodine compounds is the first of its kind in this unique region of sea ice rich in biology and rich in iodine chemistry.

  5. Iodine emissions from the sea ice of the Weddell Sea

    NASA Astrophysics Data System (ADS)

    Atkinson, H. M.; Huang, R.-J.; Chance, R.; Roscoe, H. K.; Hughes, C.; Davison, B.; Schönhardt, A.; Mahajan, A. S.; Saiz-Lopez, A.; Hoffmann, T.; Liss, P. S.

    2012-11-01

    Iodine compounds were measured above, below and within the sea ice of the Weddell Sea during a cruise in 2009, to make progress in elucidating the mechanism of local enhancement and volatilisation of iodine. I2 mixing ratios of up to 12.4 pptv were measured 10 m above the sea ice, and up to 31 pptv was observed above surface snow on the nearby Brunt Ice Shelf - large amounts. Atmospheric IO of up to 7 pptv was measured from the ship, and the average sum of HOI and ICl was 1.9 pptv. These measurements confirm the Weddell Sea as an iodine hotspot. Average atmospheric concentrations of CH3I, C2H5I, CH2ICl, 2-C3H7I, CH2IBr and 1-C3H7I were each 0.2 pptv or less. On the Brunt Ice Shelf, enhanced concentrations of CH3I and C2H5I (up to 0.5 and 1 pptv respectively) were observed in firn air, with a diurnal profile that suggests the snow may be a source. In the sea ice brine, iodocarbons concentrations were over 10 times those of the sea water below. The sum of iodide + iodate was depleted in sea ice samples, suggesting some missing iodine chemistry. Flux calculations suggest I2 dominates the iodine atom flux to the atmosphere, but models cannot reconcile the observations and suggest either a missing iodine source or other deficiencies in our understanding of iodine chemistry. The observation of new particle formation, consistent with the model predictions, strongly suggests an iodine source. This combined study of iodine compounds is the first of its kind in this unique region of sea ice rich in biology and rich in iodine chemistry.

  6. Sea salt as an ice core proxy for past sea ice extent: A process-based model study

    NASA Astrophysics Data System (ADS)

    Levine, J. G.; Yang, X.; Jones, A. E.; Wolff, E. W.

    2014-05-01

    Sea ice is a reflection of, and a feedback on, the Earth's climate. We explore here, using a global atmospheric chemistry-transport model, the use of sea salt in Antarctic ice cores to obtain continuous long-term, regionally integrated records of past sea ice extent, synchronous with ice core records of climate. The model includes the production, transport, and deposition of sea salt aerosol from the open ocean and "blowing snow" on sea ice. Under current climate conditions, we find that meteorology, not sea ice extent, is the dominant control on the atmospheric concentration of sea salt reaching coastal and continental Antarctic sites on interannual timescales. However, through a series of idealized sensitivity experiments, we demonstrate that sea salt has potential as a proxy for larger changes in sea ice extent (e.g., glacial-interglacial). Treating much of the sea ice under glacial conditions as a source of salty blowing snow, we demonstrate that the increase in sea ice extent alone (without changing the meteorology) could drive, for instance, a 68% increase in atmospheric sea salt concentration at the site of the Dome C ice core, which exhibits an approximate twofold glacial increase in sea salt flux. We also show how the sensitivity of this potential proxy decreases toward glacial sea ice extent—the basis of an explanation previously proposed for the lag observed between changes in sea salt flux and ?D (an ice core proxy for air temperature) at glacial terminations. The data thereby permit simultaneous changes in sea ice extent and climate.

  7. 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.

  8. 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.

  9. Field spectral signatures of snow, ice, and water

    NASA Astrophysics Data System (ADS)

    Satterwhite, Melvin B.; Mitchell, Herbert J.; Hemmer, Terrence; Leckie, Joseph D.

    2003-09-01

    Spectra were taken that describes free water, ice, and snow, and vegetation and inorganic backgrounds. The reflectance of water films, ranging from 0.008 to 5.35 mm, on a spectralon background varied with water depth and the water transmittance and absorbtance properties. Thin water films, > 3.5 mm, quenched the short wave infrared (SWIR) reflectance, even though moderate visible-near infrared reflectance occurred from the water-spectralon surfaces. Ice and snow have a similar number of absorption bands as water but their absorption maxima varied from those of water. River float-ice and glacial ice have diagnostic absorption features at 1.02 and 1.25 ?m and negligible reflectance in the > 1.33 ?m region. New powder snow, new wet snow, and older deep snow packs have similar shaped reflectance spectra. Thin snow accumulations readily masked the underlying surfaces. These snow pack surfaces have a small asymmetric absorption features at 0.90 ?m and strong asymmetric absorption features at 1.02, 1.25, and 1.50 ?m. These snow packs have measurable SWIR reflectance. An avalanche snow pack had low SWIR reflectance, which was similar to ice spectra. Water, ice and snow and ice surfaces have spectrally distinct features, which differentiates them and the background surfaces.

  10. Tracer studies of pathways and rates of meltwater transport through Arctic summer sea ice

    E-print Network

    Eicken, Hajo

    Tracer studies of pathways and rates of meltwater transport through Arctic summer sea ice H. Eicken) program's field site in the northern Chukchi Sea, snow and ice meltwater flow was found to have a strong impact on the heat and mass balance of sea ice during the summer of 1998. Pathways and rates of meltwater

  11. Epidemic of fractures during period of snow and ice

    Microsoft Academic Search

    Z A Rális

    1981-01-01

    During four days of snow and ice in which more than 70% of pavements in the Cardiff area were covered by slippery hard snow and ice the number of patients who attended the accident and emergency department at this hospital with fractured bones increased 2.85 times as compared with those who attended during four control days with comparable hours of

  12. Global mountain snow and ice loss driven by dust and black carbon radiative forcing

    NASA Astrophysics Data System (ADS)

    Painter, T. H.

    2014-12-01

    Changes in mountain snow and glaciers have been our strongest indicators of the effects of changing climate. Earlier melt of snow and losses of glacier mass have perturbed regional water cycling, regional climate, and ecosystem dynamics, and contributed strongly to sea level rise. Recent studies however have revealed that in some regions, the reduction of albedo by light absorbing impurities in snow and ice such as dust and black carbon can be distinctly more powerful than regional warming at melting snow and ice. In the Rocky Mountains, dust deposition has increased 5 to 7 fold in the last 150 years, leading to ~3 weeks earlier loss of snow cover from forced melt. In absolute terms, in some years dust radiative forcing there can shorten snow cover duration by nearly two months. Remote sensing retrievals are beginning to reveal powerful dust and black carbon radiative forcing in the Hindu Kush through Himalaya. In light of recent ice cores that show pronounced increases in loading of dust and BC during the Anthropocene, these forcings may have contributed far more to glacier retreat than previously thought. For example, we have shown that the paradoxical end of the Little Ice Age in the European Alps beginning around 1850 (when glaciers began to retreat but temperatures continued to decline and precipitation was unchanged) very likely was driven by the massive increases in deposition to snow and ice of black carbon from industrialization in surrounding nations. A more robust understanding of changes in mountain snow and ice during the Anthropocene requires that we move past simplistic treatments (e.g. temperature-index modeling) to energy balance approaches that assess changes in the individual forcings such as the most powerful component for melt - net solar radiation. Remote sensing retrievals from imaging spectrometers and multispectral sensors are giving us more powerful insights into the time-space variation of snow and ice albedo.

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

    Microsoft Academic Search

    A. RANGO; W. P. WERGIN; E. F. ERBE; E. G. JOSBERGER

    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

  14. 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)

  15. Mapping Antarctic sea ice thickness distribution from above and below

    NASA Astrophysics Data System (ADS)

    Maksym, T. L.; Wilkinson, J.; Singh, H.; Lewis, M.; Hochheim, K.; Wagner, T.

    2011-12-01

    Understanding of Antarctic sea ice processes, both small and large scale, have been hampered by our inability to reliably monitor ice thickness distribution from space, primarily due to the confounding role of its snow cover. This is highlighted by a large discrepancy between recent ice thickness estimates from ICESat and ship-based observations. We present a first look at results from a recent British Antarctic Survey led expedition, ICEBell, to map selected sea ice floes close to the Antarctic Peninsula coast in the Weddell and Bellingshausen Seas in November, 2010. This combined, for the first time, three-dimensional ice draft measurements from an autonomous underwater vehicle, coincident with detailed in situ mapping, and airborne lidar mapping of the surface topography to comprehensively map sea ice floes in detail. These measurements were made near-contemporaneously and nearly collocated with two NASA IceBridge flights which will both place our measurements within a broader regional context and provide some validation of the IceBridge measurements. Several process studies were also undertaken - ice mass balance buoys deployed to investigate sea ice melt processes and investigations of remote sensing signatures of the ice. Ice was generally very heavily deformed, with drafts of surveyed floes averaging over three meters, much of it under deep snow cover. I will discuss how these data might be used to move beyond simple mass balance relationships and use spatial morphological information to develop improved relationships between snow and ice thickness distributions, and hence, improved algorithms for determining Antarctic sea ice thickness from space.

  16. Sea ice and polar climate in the NCAR CSM

    SciTech Connect

    Weatherly, J.W.; Briegleb, B.P.; Large, W.G. [National Center for Atmospheric Research, Boulder, CO (United States). Climate and Global Dynamics Div.] [National Center for Atmospheric Research, Boulder, CO (United States). Climate and Global Dynamics Div.; Maslanik, J.A. [Univ. of Colorado, Boulder, CO (United States)] [Univ. of Colorado, Boulder, CO (United States)

    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.

  17. Radiative transfer in atmosphere-sea ice-ocean system

    SciTech Connect

    Jin, Z.; Stamnes, K.; Weeks, W.F. [Univ. of Alaska, Fairbanks, AK (United States); Tsay, S.C. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

    1996-04-01

    Radiative energy is critical in controlling the heat and mass balance of sea ice, which significantly affects the polar climate. In the polar oceans, light transmission through the atmosphere and sea ice is essential to the growth of plankton and algae and, consequently, to the microbial community both in the ice and in the ocean. Therefore, the study of radiative transfer in the polar atmosphere, sea ice, and ocean system is of particular importance. Lacking a properly coupled radiative transfer model for the atmosphere-sea ice-ocean system, a consistent study of the radiative transfer in the polar atmosphere, snow, sea ice, and ocean system has not been undertaken before. The radiative transfer processes in the atmosphere and in the ice and ocean have been treated separately. Because the radiation processes in the atmosphere, sea ice, and ocean depend on each other, this separate treatment is inconsistent. To study the radiative interaction between the atmosphere, clouds, snow, sea ice, and ocean, a radiative transfer model with consistent treatment of radiation in the coupled system is needed and is under development.

  18. 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.

  19. 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.

  20. Recent increase in snow-melt area in the Greenland Ice sheet as an indicator of the effect of reduced surface albedo by snow impurities

    NASA Astrophysics Data System (ADS)

    Rikiishi, K.

    2008-12-01

    Recent rapid decline of cryosphere including mountain glaciers, sea ice, and seasonal snow cover tends to be associated with global warming. However, positive feedback is likely to operate between the cryosphere and air temperature, and then it may not be so simple to decide the cause-and-effect relation between them. The theory of heat budget for snow surface tells us that sensible heat transfer from the air to the snow by atmospheric warming by 1°C is about 10 W/m2, which is comparable with heat supply introduced by reduction of the snow surface albedo by only 0.02. Since snow impurities such as black carbon and soil- origin dusts have been accumulated every year on the snow surface in snow-melting season, it is very important to examine whether the snow-melting on the ice sheets, mountain glaciers, and sea ice is caused by global warming or by accumulated snow impurities originated from atmospheric pollutants. In this paper we analyze the dataset of snow-melt area in the Greenland ice sheet for the years 1979 - 2007 (available from the National Snow and Ice Data Center), which is reduced empirically from the satellite micro-wave observations by SMMR and SMM/I. It has been found that, seasonally, the snow-melt area extends most significantly from the second half of June to the first half of July when the sun is highest and sunshine duration is longest, while it doesn't extend any more from the second half of July to the first half of August when the air temperature is highest. This fact may imply that sensible heat required for snow-melting comes from the solar radiation rather than from the atmosphere. As for the interannual variation of snow-melt area, on the other hand, we have found that the growth rate of snow-melt area gradually increases from July, to August, and to the first half of September as the impurities come out to and accumulated at the snow surface. However, the growth rate is almost zero in June and the second half of September when fresh snow of high albedo covers the surface. This fact may imply that the combined operation of solar radiation and snow impurities is responsible for the recent global decline of cryosphere. Discussion about other research works will be given in the presentation in order to support the above idea.

  1. Sea ice transports in the Weddell Sea

    NASA Astrophysics Data System (ADS)

    Harms, Sabine; Fahrbach, Eberhard; Strass, Volker H.

    2001-05-01

    Time series of sea ice draft in the Weddell Sea are evaluated together with hydrographic observations, satellite passive microwave data, and ice drift for estimation of the freshwater fluxes into and out of the Weddell Sea. Ice draft is measured with moored upward looking sonars since 1990 along two transects across the Weddell Gyre. One transect, extending from the tip of the Antarctic Peninsula to Kapp Norvegia, was sampled between 1990 and 1994 and covers the flow into and out of the southern Weddell Sea. The other transect, sampled since 1996 and extending from the Antarctic continent northward along the Greenwich meridian, covers the exchange of water masses between the eastern and the western Weddell Sea. In order to relate results obtained during the different time periods, empirical relationships are established between the length of the sea ice season, derived from the satellite passive microwave data and defined as the number of days per year with the sea ice concentration exceeding 15%, and (1) the annual mean ice draft and (2) the annual mean ice volume transport. By using these empirical relationships, estimates of annual mean ice drafts and ice volume transports are derived at all mooring sites for the period February 1979 through February 1999. Wind and current force a westward ice transport in the coastal areas of the eastern Weddell Sea and a northward ice transport in the west. During the 2-year period 1991/1992 the mean ice volume export from the Weddell Sea is (50 ± 19) × 103 m3 s-1. This freshwater export is representative for a longer-term (20-year) mean and exceeds the average amount of freshwater gained by precipitation and ice shelf melt by about 19×103 m3 s-1, yielding an upper bound for the formation rate of newly ventilated bottom water in the Weddell Sea of 2.6 Sv.

  2. Impact of subgrid-scale ice thickness distribution on heat flux on and through sea ice

    NASA Astrophysics Data System (ADS)

    Komuro, Yoshiki; Suzuki, Tatsuo

    2013-11-01

    We evaluated the impact of subgrid-scale ice thickness distribution on the heat flux on and through sea ice in a numerical model. An ice-ocean coupled model with a subgrid-scale ice thickness distribution scheme, COCO4.5, is forced by an atmospheric climatology to simulate the present state of the sea ice and ocean. The modeled climatology reproduces the ice cover reasonably well with a realistic ice thickness distribution. The heat flux on and through the sea ice is established using the grid-averaged sea-ice and snow-on-ice thickness from the results of the simulation. When the grid-averaged thickness is calculated as a weighted arithmetic mean, the conductive heat flux through the ice and snow is underestimated compared with that actually driving the model. This underestimation becomes smaller in magnitude when either a weighted harmonic mean or a weighted arithmetic mean with a modification based on the ratio of these two types of means is used. Rearrangement of the ice categories shows that the flux bias decreases with an increase in the number of categories. We also perform a sensitivity experiment in which the model is forced by the biased heat flux identified using the arithmetic mean of the ice thickness. A significant decrease in ice volume is found, notably in the Arctic Ocean. These results suggest that sea-ice models without an ice thickness distribution scheme underestimate the conductive heat flux through ice, and thereby the resultant sea-ice thickness, because the ice thickness from these models typically corresponds to the weighted arithmetic mean thickness.

  3. Selection of Effective and Efficient Snow Removal and Ice Control Technologies for Cold Region Bridges

    Microsoft Academic Search

    Jing Zhang; Debendra K. Das; Rorik Peterson

    In cold regions, snow and ice pose serious hazards to motorists. In order to minimize their detrimental effects caused by snow and ice on roadways, snow removal and ice control measures are necessary. So far, there is no single solution for snow and ice control on roadways. The aim of this work is to provide a procedure of selection of

  4. 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.

  5. 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.

  6. Remote sensing of sea ice: advances during the DAMOCLES project

    NASA Astrophysics Data System (ADS)

    Heygster, G.; Alexandrov, V.; Dybkjær, G.; von Hoyningen-Huene, W.; Girard-Ardhuin, F.; Katsev, I. L.; Kokhanovsky, A.; Lavergne, T.; Malinka, A. V.; Melsheimer, C.; Toudal Pedersen, L.; Prikhach, A. S.; Saldo, R.; Tonboe, R.; Wiebe, H.; Zege, E. P.

    2012-12-01

    In the Arctic, global warming is particularly pronounced so that we need to monitor its development continuously. On the other hand, the vast and hostile conditions make in situ observation difficult, so that available satellite observations should be exploited in the best possible way to extract geophysical information. Here, we give a résumé of the sea ice remote sensing efforts of the European Union's (EU) project DAMOCLES (Developing Arctic Modeling and Observing Capabilities for Long-term Environmental Studies). In order to better understand the seasonal variation of the microwave emission of sea ice observed from space, the monthly variations of the microwave emissivity of first-year and multi-year sea ice have been derived for the frequencies of the microwave imagers like AMSR-E (Advanced Microwave Scanning Radiometer on EOS) and sounding frequencies of AMSU (Advanced Microwave Sounding Unit), and have been used to develop an optimal estimation method to retrieve sea ice and atmospheric parameters simultaneously. In addition, a sea ice microwave emissivity model has been used together with a thermodynamic model to establish relations between the emissivities from 6 GHz to 50 GHz. At the latter frequency, the emissivity is needed for assimilation into atmospheric circulation models, but is more difficult to observe directly. The size of the snow grains on top of the sea ice influences both its albedo and the microwave emission. A method to determine the effective size of the snow grains from observations in the visible range (MODIS) is developed and demonstrated in an application on the Ross ice shelf. The bidirectional reflectivity distribution function (BRDF) of snow, which is an essential input parameter to the retrieval, has been measured in situ on Svalbard during the DAMOCLES campaign, and a BRDF model assuming aspherical particles is developed. Sea ice drift and deformation is derived from satellite observations with the scatterometer ASCAT (62.5 km grid spacing), with visible AVHRR observations (20 km), with the synthetic aperture radar sensor ASAR (10 km), and a multi-sensor product (62.5 km) with improved angular resolution (Continuous Maximum Cross Correlation, CMCC method) is presented. CMCC is also used to derive the sea ice deformation, important for formation of sea ice leads (diverging deformation) and pressure ridges (converging). The indirect determination of sea ice thickness from altimeter freeboard data requires knowledge of the ice density and snow load on sea ice. The relation between freeboard and ice thickness is investigated based on the airborne Sever expeditions conducted between 1928 and 1993.

  7. Arctic sea ice freeboard heights from satellite altimetry

    NASA Astrophysics Data System (ADS)

    Renganathan, Vidyavathy

    The Arctic sea ice cover is most sensitive to climate change and variability, mainly due to the ice-albedo feedback effect. With an increase in the average temperature across the Arctic during the past few decades, sea ice has been melting rapidly. The decline in the sea ice extent was estimated as 10% per decade since satellite observations began in 1979. Sea ice thickness is an important parameter that moderates the heat exchange between the ocean and the atmosphere, extent of sea ice deformation and sea ice circulation in the Arctic Ocean. In addition, sea ice thermodynamics and dynamics depend on the thickness of the sea ice cover. In order to estimate the trend in the sea ice volume, both the extent and thickness must be known. Hence, it is important to measure the sea ice freeboard (a representative fraction of the thickness) distribution in the Arctic Ocean. In this thesis, the total ice freeboards (height of the snow/ice surface above the sea level) were derived from satellite laser altimetry. NASA's Ice Cloud and Land Elevation Satellite (ICESat) carries a Geoscience Laser Altimetry System (GLAS) onboard, and provides dense coverage of snow (or sea ice) surface heights in the Arctic Ocean up to 86° N. The total freeboard height at each ICESat footprint location was computed by removing the instantaneous sea surface height from the ice/snow surface height. In this study, the instantaneous sea surface heights were modeled using a combination of geodetic and oceanographic models. In order to improve the accuracy of the freeboard estimation, an accuracy assessment of the ocean tide models (one of the component models in the sea surface height estimation) in the Arctic Ocean was performed. The Arctic Ocean Tide Inverse Model (AOTIM-5) was found to have the best accuracy in the Arctic Ocean and was, therefore, used in the sea ice freeboard estimation. It was also shown that the present generation of ocean tide models have ignored the ice-tide interaction processes in the model parameterization, as they are not constrained by observations from sea ice covered regions. A sensitivity analysis of the freeboard estimation procedure indicates an uncertainty of ˜0.24 m over a length scale of 100 km. The estimated total ice freeboards were compared with freeboard measurements from other methods (e.g. 'lowest level'), and a good agreement was found between the two methods at regional scales. The sea ice thickness, in the multi-year ice region north of Greenland and Ellesmere Island, was also derived from the total ice freeboard heights by assuming a hydrostatic equilibrium condition. The estimated thicknesses were compared with the thickness measurements from a Helicopter-borne Electromagnetic Induction technique. The difference between the means of the two thickness distributions was ˜0.53 m, which is well below the accuracy of the thickness estimates of ˜0.98 m. The sea ice freeboard estimation procedure, demonstrated in this study, can also be applied to upcoming laser and radar altimetry missions, such as Cryosat-2 and ICESat-2, to continuously monitor the regional, seasonal and inter-annual changes in the Arctic sea ice freeboard (and thickness) distribution.

  8. 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.

  9. Arctic Sea ice at a new low

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-09-01

    On 26 August, Arctic sea ice cover dipped to 4.1 million square kilometers, 70,000 square kilometers below the 2007 mark, which was previously the lowest extent of ice cover in the satellite record, according to an analysis of satellite data by scientists with NASA and the National Snow and Ice Data Center (NSIDC) of the University of Colorado, Boulder. “By itself it's just a number, and occasionally records are going to get set. But in the context of what's happened in the last several years and throughout the satellite record, it's an indication that the Arctic sea ice cover is fundamentally changing,” said NSIDC scientist Walt Meier. “The persistent loss of perennial ice cover—ice that survives the melt season—led to this year's record summertime retreat. Unlike 2007, temperatures were not unusually warm in the Arctic this summer,” said Joey Comiso, senior research scientist at NASA's Goddard Space Flight Center, in Greenbelt, Md. The six lowest ice extents in the satellite record have occurred in the last 6 years, according to NSIDC.

  10. 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)

  11. Spatial and Temporal Variability of Surface Snow Accumulation and Snow Chemistry at East Antarctic Ice Sheet

    NASA Astrophysics Data System (ADS)

    Motoyama, H.; Ito, K.; Hirabayashi, M.

    2014-12-01

    Snow stakes along the traverse routes have been observed for long term monitoring program 'the variation of ice sheet surface mass balance' from the 1960's by the Japanese Antarctic Research Expedition in Shirase glacier drainage basin, East Antarctica. During the traverse route between coastal S16 point (69 02'S, 40 03'E, 580m a.s.l.) to inland Dome Fuji (77 22'S, 39 42'E, 3,810m a.s.l.), the snow stake observations every 2 km have been carried out from 1993. Yearly net snow accumulations from S16 to Dome Fuji were calculated. Heavy, modern and light snow events were observed. They were different in way accumulating spatial pattern depending on places. The yearly accumulation rates were compared with seasonal change of AAO-index (SAM). As a result, yearly accumulation rate and AAO-index showed the positive correlation.Surface snow samplings were conducted every 10km along the traverse route. Generally, the snow surface features are classified into three regions. (1) the coastal region: smooth surface, high snow accumulation (2) the katabatic slope region: rough sastrugi surface and smooth glazed surface(3) the high plateau region: smooth surface, little snow accumulation The chemistry of surface snow changes from the coast to inland. Furthermore, the chemical properties of snow are different for each surface at the same area. We can classify the surface snow with fresh drifting snow, deposited drift snow, soft and hard surface snow, sustrugi, surface hoar and so on. The value of each isotope ration and ion concentration greatly varied. Sometimes, snow might deposit thick equally. But the deposited snow was redistributed by the wind. When the snowstorm occurred, the blowing snow started to deposit in a certain opportunity. As for it, the area was not the uniform. It is necessary to discuss inhomogeneity of the depositional condition quantitatively.

  12. Sea ice dynamics influence halogen deposition to Svalbard

    NASA Astrophysics Data System (ADS)

    Spolaor, A.; Gabrieli, J.; Martma, T.; Kohler, J.; Björkman, M.; Isaksson, E.; Varin, C.; Vallelonga, P.; Plane, J. M. C.; Barbante, C.

    2013-03-01

    Sea ice is an important parameter in the climate system and its changes impact upon the polar albedo and the atmospheric and oceanic circulation. Iodine (I) and bromine (Br) have been measured in a shallow ice core drilled at the summit of the Holtedahlfonna glacier (Northwest Spitsbergen, Svalbard). Changing I concentrations can be linked to the spring maximum sea ice extension. Bromine enrichment, indexed to the Br/Na sea water mass ratio, appears to be influenced by changes in the seasonal sea ice area. I is emitted from marine biota and so the retreat of spring sea ice coincides with enlargement of the open ocean surface which enhances marine primary production and consequent I emission. The observed Br enrichment can be explained by greater Br emissions during the Br explosion that have been observed to occur above first year sea ice during the early springtime. In this work we present the first comparison between halogens in surface snow and Arctic sea ice extension. Although further investigation is required to characterize potential depositional and post-depositional processes, these preliminary findings suggest that I and Br can be linked to variability in the spring maximum sea ice extension and seasonal sea ice surface area.

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

    E-print Network

    Eisenman, Ian

    Processes driving sea ice variability in the Bering Sea in an eddying ocean/sea ice model: Mean 17 September 2014 Available online 28 September 2014 Keywords: Sea ice Ice growth/melt Sea ice motion Heat flux Climate dynamics Bering Sea a b s t r a c t The seasonal cycle of sea ice variability

  14. 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.

  15. 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.

  16. Sea-ice velocity fields estimation on Ross Sea with NOAA-AVHRR

    SciTech Connect

    Flores, M.M.; Maitre, H. [ENST, Paris (France)] [ENST, Paris (France); Parmiggiani, F. [IMGA-CNR, Modena (Italy)] [IMGA-CNR, Modena (Italy)

    1995-09-01

    A complete methodology is proposed for automatic tracking of sea-ice in daylight AVHRR data. Two aspects are specially outlined: the use of partially cloudy monocular images and the estimation of ice pack trajectories along an image sequence. First, a classification technique is applied for the detection of snow-ice regions. Then, an optimal matching filter is used for the sea-ice motion estimation. The derived vector field is homogeneous and shows the ice pack motion along three days image data.

  17. 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.

  18. Abundance and composition of the sea-ice meiofauna in off-shore pack ice of the Beaufort Gyre in summer 2002 and 2003

    Microsoft Academic Search

    Rolf R. Gradinger; Klaus Meiners; Gerry Plumley; Qing Zhang; Bodil A. Bluhm

    2005-01-01

    We studied the abundance, biomass and potential ingestion rates of meiofauna in multi-year sea ice (MYI) of the Beaufort Gyre during two icebreaker expeditions in summers 2002 and 2003. Ice cores were taken at a total of ten stations and analyzed for ice temperature, salinity, chlorophyll a (Chl a), and ice meiofauna abundances. In 2002, ice was free of snow

  19. 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.

  20. Antarctic sea ice climatologies and trends in multiple data sets

    NASA Astrophysics Data System (ADS)

    Schneider, D. P.; Shea, D.; Deser, C.

    2012-12-01

    Sea ice is an important climatic variable as a regulator of fluxes of heat, water, and momentum between the ocean and the atmosphere. It is also a key indicator of climate change. In the Antarctic, sea ice extent has been reported to show a small but significant increase during the modern satellite era, 1979-present. Many researchers, especially modelers, consider sea ice to be "well-observed." However, numerous algorithms have been developed to estimate the average concentration of sea ice within a given spatial footprint based on satellite-derived passive microwave brightness temperatures. The algorithms have differing sensitivities to sources of uncertainty, such as weather (primarily water vapor and winds), the presence of snow on top of sea ice, and melt ponds. Some data sets consist of time series formed using a single algorithm, while other data sets combine multiple algorithms and data sources. A guide to the numerous data sets is available at http://climatedataguide.ucar.edu/seaice. Here we compare multiple climatologies of satellite-derived Antarctic sea ice concentration and monthly, Antarctic-wide extent and area. Large, systematic differences are revealed; for example, the spread in Antarctic-wide sea ice area for the September maximum is about 2.2x10^6 km^2, an area the size of Greenland. This has implications for evaluating coupled climate models (including CMIP5 models) and for forcing atmospheric models with "observed" sea ice. In some cases, a "multi-data set" ensemble may be more appropriate for model evaluation, rather than a single estimate of the sea ice state. Most of the data sets show a general increase in Antarctic sea ice extent and area; the significance of these trends will be discussed. There are further differences on the regional scale; we investigate whether the trends of sea ice concentration are dependent on the climatological sea ice concentration.

  1. 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.

  2. 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.

  3. Radar altimetry over sea ice

    NASA Technical Reports Server (NTRS)

    Powell, J.

    1984-01-01

    To study the sea-ice interactive region in the Bering and Greenland Seas a series of experimental compaigns, the Marginal Ice Zone Experiment (MIZEX) has been planned. A major objective of MIZEX is the development of a capability to relate the morphology and distribution of the sea ice to atmospheric and oceanographic parameters in an overall model. During the first part of the MIZEX, a 13.7 GHz microwave radar altimeter/scatterometer having a pulse length of 16 nanoseconds was flown over the Bering Sea Marginal ice zone. On the same aircraft were the NASA GSFC 19 GHz Electronically Scanning Microwave Radiometer (ESMR), scanning radiometers and an infrared, nadir pointing, temperature sounder. The altimeter/scatterometer was operated in nadir pointing and conically scanning modes to collect measurements of reflectivity and pulse shapes. These will be related to sea-ice classifications, ocean wave spectra and coincident microwave and infrared radiometric measurements and laser profilometer surface roughness estimates.

  4. 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.

  5. Geochemical Characteristics And Zones Of Surface Snow On East Antarctic Ice sheet

    NASA Astrophysics Data System (ADS)

    Kang, J.

    2004-12-01

    Geochemical characteristics and zones of surface snow on east Antarctic Ice Sheet Jiancheng KANG1,4, Leibao LIU1, Dahe QIN2, Dali WANG1, Jiahong WEN1, Dejun TAN1, Zhongqin LI2, Jun LI3 & Xiaowei ZHANG1,4 1 Polar Research Institute of China, Shanghai 200129, China; 2 Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; 3 Australian Antarctic Division and Antarctic Climate and Ecosystems CRC, Private Bag 80 Hobart, Tasmania, 7001, Australia; 4 Geography Department of Lanzhou University, Lanzhou 730000, China Correspondence should be addressed to Jiancheng KANG (email: kangjc@sh163.net, kangjc@126.com ) Abstract The surface-snow geochemical characteristics are discussed on the East Antarctic Ice Sheet, depending on the stable isotopes ratios of oxygen and hydrogen, concentration of impurities (soluble-ions and insoluble micro-particle) in surface snow collected on the ice sheet. The purpose is to study geochemical zones on the East Antarctic Ice Sheet and to research sources and transportation route of the water vapor and the impurities in surface snow. It has been found that the ratio coefficients, as S1, d1 in the equation ƒOD = S1ƒO18O + d1, are changed near the elevation 2000m on the ice sheet. The weight ratio of Cl-/Na+ at the area below the elevation of 2000m is close to the ratio in the sea salt; but it is about 2 times that of the sea salt, at the inland area up to the elevation of 2000m. The concentrations of non-sea-salt Ca2+ ion (nssCa2+) and fine-particle increase at the interior up to the elevation 2000m. At the region below the elevation of 2000m, the impurity concentration is decreasing with the elevation increasing. Near coastal region, the surface snow has a high concentration of impurity, where the elevation is below 800m. Combining the translating processes of water-vapor and impurities, it suggests that the region up to the elevation 2000m is affected by large-scale circulation with longitude-direction, and that water-vapor and impurities in surface snow come from long sources. The region below the elevation 2000m is affected by some strong cyclones acting at peripheral region of the ice sheet, the sources of water and impurities could be at high latitude sea and coast. The area below elevation 800m is affected by local coastal cyclones. Keywords: Antarctic Ice Sheet, Snow, Geochemical Zones

  6. Surface Roughness Impact on the Sea Ice Thickness Measurements Based on LIDAR/Radar Altimetry

    NASA Astrophysics Data System (ADS)

    Li, L.; Truesdale, D.; Posey, P.; Allard, R.; Gardner, J. M.; Brozena, J. M.; Richter-Menge, J.

    2013-12-01

    The Radar and/or LIDAR measurements of sea ice freeboard provide an indirect approach to infer sea ice thickness via isostasy. The underlying assumption is that the LIDAR signal returns at the air/snow interface and radar signal at the snow/ice interface. Thus the surface roughness at the air, snow and ice interface has a significant impact on the LIDAR/Radar returns, which can lead to very significant errors in the ice thickness retrievals. Recent Cryosat-2 validation results suggest that its altimetry-based technique is very effective in mapping hemispheric sea ice thickness. However, in some cases significant bias exists in the Cryosat-2 data product. To understand the performance of those data depends on our skills in quantifying the impacts of the secondary parameters, such as surface roughness of snow and ice surfaces and the penetration depth of the snow/ice by the radar. To this end, we analyze airborne radar and lidar altimeter data collected during a Cryosat-2 under-flight by the NRL and the NASA IceBridge missions, as well as the in-situ data from the coordinated CRREL/NRL field campaign. In this presentation we will show some surface roughness data from airborne LIDAR for leveled and deformed first year ice, and ice pressure ridges. Their impacts on radar returns and sea ice thickness retrieval will be presented.

  7. Sea ice and icing risk for offshore wind turbines

    Microsoft Academic Search

    L. Battisti; R. Fedrizzi; A. Brighenti; T. Laakso

    There are two important issues related to wind turbines performances in offshore sites that locate in cold cli- mates: sea ice (flows, driving ice, land-fast ice) and the presence of atmospheric icing (due to water in the air as in-cloud operation, rainfall and sea sprays) which may potentially lead to ice formation on turbines' struc- tures. Icing of rotor blades

  8. March of the Polar Bears: Global Change, Sea Ice, and Wildlife Migration

    NSDL National Science Digital Library

    Venugopal Bhat

    In this activity students use NASA satellite data to study changes in temperature and snow-ice coverage in the South Beaufort Sea, Alaska. They will then correlate the data with USGS ground tracking of polar bears and relate their findings to global change, sea ice changes, and polar bear migration and survival.

  9. March of the Polar Bears: Global Change, Sea Ice, and Wildlife Migration

    NSDL National Science Digital Library

    Students will use NASA satellite data to study temperature and snow-ice coverage in the South Beaufort Sea, Alaska. The data can be used to correlate with USGS ground tracking of polar bears, and to relate this to global change, sea ice changes, and polar bear migration. The data can be used to draw conclusions surrounding any migration patterns in the region.

  10. Mercury deposition to snow and ice provides a link between the lower atmosphere and the cryosphere in northern Alaska

    NASA Astrophysics Data System (ADS)

    Douglas, T. A.; Sturm, M.; Simpson, W. R.; Alvarez-Aviles, L.; Blum, J. D.; Perovich, D. K.; Keeler, G. J.; Lammers, A.; Biswas, A.

    2005-12-01

    We investigated a wide range of snow and ice forms as potential scavengers of atmospheric mercury during mercury depletion events (MDEs). Our work was part of a large campaign near Barrow, Alaska in the spring of 2005 (LEADEX-2005). Gaseous and reactive phase mercury, ozone and halogen oxide measurements were made at numerous locations along the Arctic Ocean Coast as part of the campaign and allowed us to identify when MDEs were occurring. Results from previous work implicated sea ice leads and the near shore coastal snow pack as locations where elevated mercury concentrations in frost flowers (75-185 ng/L) and surface hoar (~900 ng/L) were likely. In LEADEX-2005 the previous work was expanded by sampling snow along transects away from the lead edge and from daily sampling of diamond dust and surface snow at a site located 6 kilometers inland from the lead. Vapor condensate was also collected on chilled sample bottles hoisted above the lead on a 2 m2 kite and from a 2-m high pole. We also sampled surface hoar, rime ice, wind slab, fresh snow and blowing snow near the leads. Diamond dust was collected in glass trays and rime was scraped from the leading edge of an unmanned aerial vehicle wing. Nilas and frost flowers of varying ages were collected from a boat in open water at the lead. Elevated mercury concentrations were measured in virtually every type of vapor deposited snow or ice form, including some samples that yielded concentrations well over 1000 ng/L. Our results suggest that deposition of mercury to snow and ice during MDEs is controlled by four processes: 1) scavenging during crystallization or snow fall, 2) impaction of mercury laden aerosols onto crystalline surfaces, 3) sublimation of snow and ice, and 4) condensation driven by temperature gradients. We believe these four factors combine to control elevated mercury concentrations where the lower atmosphere and cryosphere meet.

  11. Radar Polarimetry of Sea Ice

    NASA Astrophysics Data System (ADS)

    Drinkwater, M.

    2003-04-01

    Dating back to 1988, polarimetric SAR imaging has been demonstrated from a variety of airborne platforms but in only a relatively limited variety of polar sea ice locations. Data were first acquired by NASA-JPL in the context of the SSMI calibration and validation campaign using the C-, L-, and P-band AIRSAR system. These flights were performed in the Beaufort, Chukchi and Bering Seas. Subsequently, data were acquired by the Danish EMISAR airborne system in the Greenland and Baltic Seas. To-date, however, the only spaceborne polarimetric sea-ice data have been acquired from the Space Shuttle, in the Weddell Sea, Antarctica during the SIR-C mission. These limited cases are currently being supplemented by ASAR alternating polarisation acquisitions from Envisat, thus helping to broaden our knowledge on the discriminatory capability of C-band. This presentation will review the historical background to polarimetric remote sensing of sea ice, together with the regional characteristics of the sea-ice data from these different experiments. Examples of lessons learned will be provided from previous attempts to classify sea ice, and illustrated with examples from microwave polarimetric and multi-frequency data from the above cases.

  12. Arctic Sea Ice Satellite Observations

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2008-01-17

    In this interactive activity produced for Teachers' Domain, learn how Arctic sea ice has changed over the past 25 years in terms of maximum winter extent, concentration, and the timing of breakup each spring.

  13. 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.

  14. Observations of the annual cycle of sea ice temperature and mass balance

    Microsoft Academic Search

    Donald K. Perovich; Bruce C. Elder; Jacqueline A. Richter-Menge

    1997-01-01

    A vertical array of thermistors coupled with an autonomous data-logging system was used to obtain a 15-month record of ice temperature profiles in a multiyear floe in the Beaufort Sea. This record was used to monitor atmosphere, ice, and ocean temperatures, determine changes in the ice mass balance, and infer estimates of the ocean heat flux and the snow thermal

  15. A Modern Concept for Autonomous and Continuous Measurements of Spectral Albedo and Transmissivity of Sea Ice

    NASA Astrophysics Data System (ADS)

    Nicolaus, M.; Hudson, S. R.; Gerland, S.; de La Rosa, S.; Sirevaag, A.

    2009-12-01

    Sea ice and its snow cover play a key role in the climate and ecosystems in and beyond both Polar Regions. Especially in the Arctic, significant changes of sea-ice regimes towards higher fractions of younger and thinner sea ice have been observed during the last decades, but the reasons for these changes and their consequences are not yet fully understood. The interaction of solar radiation with snow and ice can drive important feedback processes that affect the sea-ice energy and mass balance. Improving our knowledge about these processes is of critical importance for understanding other physical, biological, and geochemical processes not only in snow and sea ice, but also in the upper ocean. Though several studies on albedo and transmissivity of snow and sea ice have been performed, the knowledge about spectral and total fluxes and their seasonality is still limited, especially under sea ice. But knowledge of how short-wave radiation is partitioned is of high importance when studying biological activity and its seasonal evolution. There is a strong need to quantify how much energy is reflected to the atmosphere, is absorbed in snow and ice, and is transmitted into the ocean, and how is this energy spectrally partitioned. Here we present a modern setup for autonomous, continuous and high temporal resolution measurements of spectral albedo and transmissivity of snow and sea ice. The setup is designed for use under challenging climatic conditions over long times and during different seasons. The measurements are performed using TriOS Ramses spectral radiometers, covering a wavelength range from 330-920 nm. The setup consists of three sensors, measuring incident and reflected radiation above the ice and radiation transmitted through the ice. From these measurements, time series of spectral albedo and transmissivity of snow and sea ice can be derived. The system described has been used successfully on sea ice for both short-term monitoring (days to weeks) and seasonal monitoring from late winter to autumn freeze-up, both with and without routine visits by observers. Beyond a methodological description of sensors and setup, we present sample data sets collected during the last years on Arctic sea ice. The setup has performed well under various conditions and the data sets stand out for high quality data. Comparisons to approved radiation measurements are shown, too. Setup for autonomous and continuous measurements of spectral radiation on sea ice

  16. The sensitivity of a one-dimensional thermodynamic sea ice model to changes in cloudiness

    NASA Technical Reports Server (NTRS)

    Shine, K. P.; Crane, R. G.

    1984-01-01

    A thermodynamic sea ice-lead model is used to assess the importance of cloud cover changes to modeled ice thickness. For regions of either permanent multiyear ice or seasonal sea ice, the cloud amount variations have relatively little impact. However, for regions where the presence of summer ice is variable from year to year, the predicted ice thickness is strongly dependent on cloud cover. In general, with a snow covered surface, decreased cloud leads to surface cooling while increased cloud gives rise to a surface warming. For a melting bare ice surface, the reverse occurs. The ice model response time is too long for interannual variations in cloud amount to explain interannual variations in ice thickness and extent. Nevertheless, the implication of the results is that numerical modeling of sea ice distribution requires accurate cloud data or cloud prediction and that trends in cloud cover may lead to significant perturbations in sea ice extent and thickness.

  17. Bacteria Assists in Formation of Ice and Snow

    NSDL National Science Digital Library

    NPR Talk of the Nation Science Friday Audio Story: New work in the journal Science suggests that bacteria may have played an important role in guiding the formation of the snow and rain forming ice crystals found in high-level clouds. The researchers looked at snow samples from around the globe — including Montana, France and Antarctica — and found that cells and cell fragments were a significant part of the aerosol particles that lead to the formation of ice and raindrops. Brent C. Christner, a member from the research team, talks with guest host Joe Palca about the connection between microbiology and meteorology.

  18. 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.

  19. The NRL 2011 Airborne Sea-Ice Thickness Campaign

    NASA Astrophysics Data System (ADS)

    Brozena, J. M.; Gardner, J. M.; Liang, R.; Ball, D.; Richter-Menge, J.

    2011-12-01

    In March of 2011, the US Naval Research Laboratory (NRL) performed a study focused on the estimation of sea-ice thickness from airborne radar, laser and photogrammetric sensors. The study was funded by ONR to take advantage of the Navy's ICEX2011 ice-camp /submarine exercise, and to serve as a lead-in year for NRL's five year basic research program on the measurement and modeling of sea-ice scheduled to take place from 2012-2017. Researchers from the Army Cold Regions Research and Engineering Laboratory (CRREL) and NRL worked with the Navy Arctic Submarine Lab (ASL) to emplace a 9 km-long ground-truth line near the ice-camp (see Richter-Menge et al., this session) along which ice and snow thickness were directly measured. Additionally, US Navy submarines collected ice draft measurements under the groundtruth line. Repeat passes directly over the ground-truth line were flown and a grid surrounding the line was also flown to collect altimeter, LiDAR and Photogrammetry data. Five CRYOSAT-2 satellite tracks were underflown, as well, coincident with satellite passage. Estimates of sea ice thickness are calculated assuming local hydrostatic balance, and require the densities of water, ice and snow, snow depth, and freeboard (defined as the elevation of sea ice, plus accumulated snow, above local sea level). Snow thickness is estimated from the difference between LiDAR and radar altimeter profiles, the latter of which is assumed to penetrate any snow cover. The concepts we used to estimate ice thickness are similar to those employed in NASA ICEBRIDGE sea-ice thickness estimation. Airborne sensors used for our experiment were a Reigl Q-560 scanning topographic LiDAR, a pulse-limited (2 nS), 10 GHz radar altimeter and an Applanix DSS-439 digital photogrammetric camera (for lead identification). Flights were conducted on a Twin Otter aircraft from Pt. Barrow, AK, and averaged ~ 5 hours in duration. It is challenging to directly compare results from the swath LiDAR with the pulse-limited radar altimeter that has a footprint that varies from a few meters to a few tens of meters depending on altitude and roughness of the reflective surface. Intercalibration of the two instruments was accomplished at leads in the ice and by multiple over-flights of four radar corner-cubes set ~ 2 m above the snow along the ground-truth line. Direct comparison of successive flights of the ground-truth line to flights done in a grid pattern over and adjacent to the line was complicated by the ~ 20-30 m drift of the ice-floe between successive flight-lines. This rapid ice movement required the laser and radar data be translated into an ice-fixed, rather than a geographic reference frame. This was facilitated by geodetic GPS receiver measurements at the ice-camp and Pt. Barrow. The NRL data set, in combination with the ground-truth line and submarine upward-looking sonar data, will aid in understanding the error budgets of our systems, the ICEBRIDGE airborne measurements (also flown over the ground-truth line), and the CRYOSAT-2 data over a wide range of ice types.

  20. 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.

  1. Jet formation at the sea ice edge

    NASA Astrophysics Data System (ADS)

    Feltham, D. L.; Heorton, H. D.

    2014-12-01

    The sea ice edge presents a region of many feedback processes between the atmosphere, ocean and sea ice, which are inadequately represented in current climate models. Here we focus on on-ice atmospheric and oceanic ?ows at the sea ice edge. Mesoscale jet formation due to the Coriolis effect is well understood over sharp changes in surface roughness such as coastlines. This sharp change in surface roughness is experienced by the atmosphere ?owing over, and ocean ?owing under, a compacted sea ice edge. We have studied a dynamic sea ice edge responding to atmospheric and oceanic jet formation. The shape and strength of atmospheric and oceanic jets during on-ice ?ows is calculated from existing studies of the sea ice edge and prescribed to idealised models of the sea ice edge. An idealised analytical model of sea ice drift is developed and compared to a sea ice climate model (the CICE model) run on an idealised domain. The response of the CICE model to jet formation is tested at various resolutions. We ?nd that the formation of atmospheric jets during on-ice winds at the sea ice edge increases the wind speed parallel to the sea ice edge and results in the formation of a sea ice edge jet. The modelled sea ice edge jet is in agreement with an observed jet although more observations are needed for validation. The increase in ice drift speed is dependent upon the angle between the ice edge and wind and can result in a 40% increase in ice transport along the sea ice edge. The possibility of oceanic jet formation during on-ice currents and the resultant effect upon the sea ice edge is less conclusive. Observations and climate model data of the polar oceans has been analysed to show areas of likely atmospheric jet formation, with the Fram Strait being of particular interest.

  2. Black Carbon and Dust in Snow and Ice on Snow Dome, Mt. Olympus

    NASA Astrophysics Data System (ADS)

    Kaspari, S.; Delaney, I.; Skiles, M.; Dixon, D. A.

    2012-12-01

    Deposition of black carbon (BC) and dust on highly reflective snow and glacier ice causes darkening of the surface, resulting in greater absorption of solar energy, heating of the snow/ice, and accelerated snow and glacier melt. The deposition of BC and dust may be affecting the timing and availability of water resources in the Pacific Northwest where the majority of runoff comes from snow and glacier melt, but minimal related research has taken place in this region. A recent modeling study suggested that BC deposition is causing a decrease in spring snow water equivalent and a shift to earlier peak runoff in the spring in the Western United States. Additionally, limited observations made in the early 1980s in Washington State determined that light absorbing impurities (e.g., BC and dust) were reducing the snow albedo. Since 2009, we have collected snow and ice samples from glaciers and the seasonal snowpack from spatially distributed sites in Washington State to determine impurity content, and to assess how impurity concentrations vary in relation to emission source proximity. Here we present results from the summer 2012 fieldwork on Snow Dome, Mt. Olympus in Washington State. Mt. Olympus is located upwind from major regional sources of BC and dust, but may receive BC from ocean shipping and trans-Pacific transport of BC and dust from large Asian sources. We used a field spectrometer to measure spectral albedo on Snow Dome, and analyzed surface snow samples and shallow ice cores to characterize the spatial and temporal variability of impurity deposition. Total impurity load was determined gravimetrically. Dust concentrations are inferred from ICPMS analyses and BC concentrations are determined using a Single Particle Soot Photometer (SP2), with select samples also analyzed for BC using a Sunset EC-OC to facilitate method inter-comparison. We assess the role that absorbing impurities may play in accelerating melt at Snow Dome, and briefly compare our results to other sites in Washington State that are downwind of large regional emission sources.

  3. EOS Aqua AMSR-E Arctic Sea Ice Validation Program: Intercomparison Between Modeled and Measured Sea Ice Brightness Temperatures

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    During March 2003, an extensive field campaign was conducted near Barrow, Alaska to validate AQUA Advanced Microwave Scanning Radiometer (AMSR) sea ice products. Field, airborne and satellite data were collected over three different types of sea ice: 1) first year ice with little deformation, 2) first year ice with various amounts of deformation and 3) mixed first year ice and multi-year ice with various degrees of deformation. The validation plan relies primarily on comparisons between satellite, aircraft flights and ground-based measurements. Although these efforts are important, key aspects such as the effects of atmospheric conditions, snow properties, surface roughness, melt processes, etc on the sea ice algorithms are not sufficiently well understood or documented. To improve our understanding of these effects, we combined the detailed, in-situ data collection from the 2003 field campaign with radiance modeling using a radiative transfer model to simulate the top of the atmosphere AMSR brightness temperatures. This study reports on the results of the simulations for a variety of snow and ice types and compares the results with the National Oceanographic and Atmospheric Administration Environmental Technology Laboratory Polarimetric Scanning Radiometer (NOAA) (ETL) (PSR) microwave radiometer that was flown on the NASA P-3.

  4. The Optical Properties of Sea Ice

    Microsoft Academic Search

    Donald K. Perovich

    Abstract Sea ice is a ,translucent material with an intricate structure and complex optical properties. Understanding the reflection, absorption, and transmis- sion of shortwave ,radiation by sea ,ice is important ,to a ,diverse array of scientific problems, including those in ice thermodynamics and polar clima- tology. Radiative transfer in sea ,ice is a ,combination ,of absorption ,and scattering. Differences in

  5. Comparison of the sea-ice thickness distribution in the Lincoln Sea and adjacent Arctic Ocean in 2004 and 2005

    Microsoft Academic Search

    C. Haas; S. Hendricks; M. Doble

    2006-01-01

    Results of helicopter-borne electromagnetic measurements of total (ice plus snow) sea-ice thickness performed in May 2004 and 2005 in the Lincoln Sea and adjacent Arctic Ocean up to 86° N are presented. Thickness distributions south of 84° N are dominated by multi-year ice with modal thicknesses of 3.9 m in 2004 and 4.2 m in 2005 (mean thicknesses 4.67 and

  6. Consistent and contrasting decadal Arctic sea ice thickness predictions from a highly optimized sea ice

    E-print Network

    Feltham, Daniel

    Consistent and contrasting decadal Arctic sea ice thickness predictions from a highly optimized sea of Arctic Ocean sea ice thickness made by a modern dynamic-thermodynamic sea ice model and forced comprehensive data sets of observations made between 1979 and 2001 of sea ice thickness, draft, extent

  7. Ice loss from West Antarctica to the Bellingshausen Sea

    NASA Astrophysics Data System (ADS)

    Bingham, R. G.; Smith, A.; King, E. C.; Gudmundsson, G. H.; Thomas, E. R.

    2014-12-01

    Determination of Antarctica's ice-sheet mass balance (more correctly, mass imbalance) is of paramount concern due to its impact on global sea levels. Monitoring with satellite remote sensing since the early 1990s has demonstrated that the imbalance has become progressively more negative, with losses dominated by the ocean-forced drawdown of ice from West Antarctica into the Amundsen and Bellingshausen Seas. Recent years have hosted unprecedented study and increased understanding of the ice-ocean processes contributing to Amundsen-Sea losses, leaving ocean-forced ice-dynamical losses to the Bellingshausen Sea relatively neglected. We therefore present here, with the aid of dedicated field data in austral season 2009/2010, a detailed assessment of the mass imbalance of Ferrigno Ice Stream (FIS), the dominant contributor of mass directly to the Bellingshausen Sea. We assess mass imbalance using the input-output method for (i) 1992, and (ii) 2010; the temporal markers being defined by the acquisition of the first comprehensive satellite-velocity coverage and the acquisition of the field measurements respectively. Input by snowfall is estimated using existing maps of Antarctic snow accumulation calibrated with 2010-acquired field data in the form of a 20-m ice core recovered at the upper FIS ice divide and englacial layering across the catchment imaged with 500 MHz over-snow radar. Output by discharge across the grounding line requires measurements of ice velocity and depth across a "flux gate." In 2010, we obtained flux gate measurements directly from the field using DGPS and 2 MHz over-snow radar, and we also refer to satellite-acquired ice-velocity data (MeASUREs) and airborne-acquired ice depths (Operation IceBridge) acquired at a similar time. Output from 1992 is calculated using 1992-acquired satellite ice-velocities (Rignot, 2006) and ice depth retroactively inferred from the 2010-acquired ice depth corrected for 1992-2010 surface elevation loss. We calculate that in 2010 FIS was losing ice at a rate of 3-4 Gt a-1 to the ocean, which was ~20% greater than in 1992. The difference is almost entirely explicable through accelerated flow across the grounding line, forced by oceanic melting.

  8. 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.

  9. Organic iodine in Antarctic sea ice: A comparison between winter in the Weddell Sea and summer in the Amundsen Sea

    NASA Astrophysics Data System (ADS)

    Granfors, Anna; Ahnoff, Martin; Mills, Matthew M.; Abrahamsson, Katarina

    2014-12-01

    Recent studies have recognized sea ice as a source of reactive iodine to the Antarctic boundary layer. Volatile iodinated compounds (iodocarbons) are released from sea ice, and they have been suggested to contribute to the formation of iodine oxide (IO), which takes part in tropospheric ozone destruction in the polar spring. We measured iodocarbons (CH3I, CH2ClI, CH2BrI, and CH2I2) in sea ice, snow, brine, and air during two expeditions to Antarctica, OSO 10/11 to the Amundsen Sea during austral summer and ANT XXIX/6 to the Weddell Sea in austral winter. These are the first reported measurements of iodocarbons from the Antarctic winter. Iodocarbons were enriched in sea ice in relation to seawater in both summer and winter. During summer, the positive relationship to chlorophyll a biomass indicated a biological origin. We suggest that CH3I is formed biotically in sea ice during both summer and winter. For CH2ClI, CH2BrI, and CH2I2, an additional abiotic source at the snow/ice interface in winter is suggested. Elevated air concentrations of CH3I and CH2ClI during winter indicate that they are enriched in lower troposphere and may take part in the formation of IO at polar sunrise.

  10. March 2003 EOS Aqua AMSR-E Arctic Sea Ice Field Campaign

    NASA Technical Reports Server (NTRS)

    Cavalieri, Donald J.; Markus, Thorsten; Maslanik, James A.; Sturm, Matthew; Lobl, Elena

    2006-01-01

    An overview of the March 2003 coordinated sea ice field campaign in the Alaskan Arctic is presented with reference to the papers in this special section. This campaign is part of the program to validate the Aqua Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) sea ice products. Standard AMSR-E sea ice products include sea ice concentration, sea ice temperature, and snow depth on sea ice. The validation program consists of three elements, namely: 1) satellite data comparisons; 2) coordinated satellite/aircraft surface measurements; and 3) modeling and sensitivity analyses. Landsat-7 and RADARSAT observations were used in comparative studies with the retrieved AMSR-E sea ice concentrations. The aircraft sensors provided high-resolution microwave imagery of the surface, atmospheric profiles of temperature and humidity, and digital records of sea ice conditions. When combined with in situ measurements, aircraft data were used to validate the AMSR-E sea ice temperature and snow-depth products. The modeling studies helped interpret the field-data comparisons, provided insight on the limitations of the AMSR-E sea ice algorithms, and suggested potential improvements to the AMSR-E retrieval algorithms.

  11. 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

  12. Soot climate forcing via snow and ice albedos

    Microsoft Academic Search

    James Hansen; Larissa Nazarenko

    2004-01-01

    Plausible estimates for the effect of soot on snow and ice albedos (1.5% in the Arctic and 3% in Northern Hemisphere land areas) yield a climate forcing of +0.3 W\\/m2 in the Northern Hemisphere. The \\

  13. 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

  14. Detection of small-scale roughness and refractive index of sea ice in passive satellite microwave remote sensing

    Microsoft Academic Search

    Sungwook Hong

    2010-01-01

    Polar ice masses and sheets are sensitive indicators of climate change. Small-scale surface roughness significantly impacts the microwave emission of the sea ice\\/snow surface; however, published results of surface roughness measurements of sea ice are rare. Knowing the refractive index is important to discriminate between objects. In this study, the small-scale roughness and refractive index over sea ice are estimated

  15. 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.

  16. Microstructural Considerations of Transporting Sea Ice Samples from Polar Regions

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    High latitude regions are at the forefront of climate change research as these regions have and will experience the greatest impact due to changing environmental conditions (e.g. Antarctic and recent Arctic stratospheric ozone holes, large temperature increases on the Antarctic Peninsula, changes in the extent and age of Arctic sea ice). One of the major challenges of polar scientific research is the preservation of frozen sea ice samples during their transport back to the laboratory and subsequent storage. Small fluctuations in temperature have been shown to have a significant effect on the microstructure of snow and ice samples. This is especially true for sea ice specimens where transport and storage temperatures are often only slightly below the eutectic point for its different constituents (i.e. salts). Furthermore, sea ice can have a 30 deg C in situ vertical temperature gradient that is lost during transport and storage. Sea ice plays a critical role in mediating the exchange of heat, gases, and chemical species across the ocean-atmosphere interface. The kinetics of these exchanges is highly dependent upon the brine channel microstructure, which is strongly coupled to temperature. To determine the degree of microstructural variation between samples shipped at different temperatures, ten samples of a single sea ice core collected in March 2012 were transported from Barrow, Alaska to Hanover, NH using two common techniques: with blue ice packs enclosed in a Styrofoam box (~ -25 deg C) and in a dry liquid nitrogen cryoshipper (~ -182 deg C). In addition, snow lying on the sea ice and blowing snow samples were collected and shipped via both techniques. All samples were then stored for analysis in a cold room maintained at ~ -33 deg C. The microstructure of both sets of samples was analyzed using x-ray micro-computed tomography (?-CT), with samples on a Peltier cold stage to maintain a scanning temperature of -20 deg C. We compare sea ice porosity and brine channel morphology between the samples shipped at -25 deg C and those from the same core depth shipped at -182 deg C. This work informed the transport and analysis of our samples collected in Antarctica in October - November 2012.

  17. Distribution and biomass transport of ice amphipods in drifting sea ice around Svalbard

    NASA Astrophysics Data System (ADS)

    Hop, Haakon; Pavlova, Olga

    2008-10-01

    Diversity and distribution of ice amphipods were determined in drifting sea ice around Svalbard during May-August 2003-2005. Sea-ice concentrations were determined visually and by satellite recordings. Backward trajectories for ice drift, based on satellite observations, indicated that multi-year ice in the area had originated 3-5 years earlier in the Kara Sea and western Laptev Sea, whereas some of the younger ice (1-2 years) may have originated in Franz Josef Land area. Quantitative collections of ice amphipods were obtained by SCUBA divers from flat areas and ridges below sea ice. The abundance and biomass were generally higher on ridges, particularly for the large Gammarus wilkitzkii, whereas Apherusa glacialis was more abundant on flat areas. Abundance and biomass varied among seasons (May-August) and years, with low values in May and higher values in July. The high values were similar to abundance and biomass values from July 1996. Redundancy analysis showed that 33% and 52% of the variability in respective species abundance and biomass could be explained by environmental variables, with ice draft and snow cover being the most important. The overall mean biomass for flats (0.30±0.05 g m -2) and ridges (1.64+0.46 g m -2) were used to calculate ice-associated biomass transport based on revised mean annual ice flux through Fram Strait (662,000 km 2 yr -1) and into the Barents Sea (total 228,000 km 2 yr -1). About 478×10 3 t WW (57×10 3 t C) of ice amphipods are transported annually through Fram Strait and 194×10 3 t WW (23×10 3 t C) into the northern Barents Sea, implying that 71% of the amphipod biomass in drifting sea ice passes through Fram Strait and 29% enters the Barents Sea. Climate induced reduction in ice thickness and extent will likely decrease this southward biomass transport, and thus the current carbon input of about 80×10 3 t C yr -1 into these marginal seas. Ice amphipod populations probably cannot be sustained if the summers become ice free in the Arctic Ocean, and particularly reduction of multi-year ice in the Arctic Ocean will affect long-lived species such as Gammarus wilkitzkii.

  18. Observations of sea ice physical properties during the sea ice electromagnetics initiative

    Microsoft Academic Search

    A. J. Gow; D. K. Perovich

    1996-01-01

    An Office of Naval Research sponsored sea ice electromagnetics research initiative has been directed towards relating the observed variability in sea ice electromagnetic signatures to changes in sea ice physical properties, and then using this information to develop forward and inverse models. In this paper the authors present an overview of laboratory and field observations made of sea ice physical

  19. Community-based sea ice thickness observatories in the Arctic

    NASA Astrophysics Data System (ADS)

    Gearheard, S.; Mahoney, A. R.; Huntington, H.; Oshima, T.; Qillaq, T.; Barry, R. G.

    2007-12-01

    The thickness of sea ice is a fundamental diagnostic variable for assessing the state of the ice cover. At the scale of the Arctic Basin, the ice thickness distribution determines the volume of the ice pack and its susceptibility to a warming climate as well as affecting the exchange of heat between the ocean and atmosphere. At the local scale, it dictates where and when it is safe to travel on the ice or through the water. Measuring the thickness of sea ice is challenging both technically and logistically and any measurement program strikes a balance between cost and coverage accordingly. Accurately measuring the thickness of large areas of sea ice generally requires airplanes, ice breakers or submarines and electromagnetic or acoustic devices. In this study, we use one of the least technical methods combined with support from remote communities to establish a set of sea ice observation stations in Barrow (Alaska), Clyde River (Baffin Island, Nunavut) and Qaanaaq (northwest Greenland). We employ hunters from these communities, who are experts in traveling and working on the ice, and train them to deploy ice observation stations and take measurements. Each station consists of snow stakes and hot-wire ice thickness gauges and the local observers take measurements on a weekly basis. Involvement of the community is fundamental to the success of these measurement programs and ensures the data collected are relevant to the local use of the sea ice. Community elders and hunters chose the station locations according to where they hunt and travel and to be representative of local variability. As partners in research, the scientists and local hunters are able to share and synthesize their knowledge; the scientific community gains a better understanding of the extraordinary depth of traditional knowledge and the communities improve their understanding of global changes and ability to adapt. Here we present data from observation stations near Clyde River and Qaanaaq. At Clyde River, in comparison with measurements taken by the Canadian Ice Service during the period 1959-93, the sea ice in 2006-07 was below but within one standard deviation of the mean thickness. Combined with local air temperature measurements from nearby meteorological stations, we calculated approximate surface energy balances that indicate the ocean heat flux is significantly greater at Qaanaaq than Clyde River, despite otherwise being similar environments for sea ice. Findings such as this are important in understanding the specific ways in which sea ice is changing in different locales and are vital for community planning for the near future.

  20. CryoSat-2 validation on land and sea ice in the western Ross Sea Region, Antarctica, based on near-surface remote sensing methods

    NASA Astrophysics Data System (ADS)

    Rack, Wolfgang; Haas, Christian; Krützmann, Nikolai; Clavano, Wendy; Pinchin, James; Gough, Alex; Langhorne, Pat

    2010-05-01

    The SAR Interferometric Radar Altimeter system (SIRAL) onboard ESA's CryoSat is designed to yield improved accuracy on ice surface elevation over conventional radar altimeters. The aim of this study is to validate CryoSat-2 measurements on land and sea ice in the Pacific Sector of Antarctica by the application of independent near-surface remote sensing methods. Information on snow and ice characteristics, e.g. density and surface roughness, is collected simultaneously in order to better understand the interaction of the radar signal with sea and land ice. The investigation area is located in the vicinity of New Zealand's Scott Base (77°51'S, 166°45'E, 14 m a.s.l.). Sea ice formation processes found here, close to the Ross Ice Shelf and McMurdo Ice Shelf, may be quite typical for Antarctica as a whole as about half of the Antarctic coastline is bordered by ice shelves. The outflow of very cold water from underneath the ice shelf favours the formation of frazil and platelet ice - important ingredients which need a better understanding in order to reliably measure and predict changes in Antarctic sea ice coverage. For land ice, this area is also quite favourable with respect to the investigation of snow/ice-microwave interaction, because a large variety of common snow or ice surface classes can be found within a reasonable short distance from Scott Base. The field work was conducted over two field seasons (2008 and 2009). The remote sensing instruments used include a helicopter borne electromagnetic inductivity device ("HEM bird") for sea ice thickness, a ground penetrating radar system to map internal snow layers as well as snow depth on sea ice, and a laser profiler and high resolution optical camera. The laser profiler and camera was operated either from the ground or mounted on an unmanned aerial vehicle (UAV). For the planning of the field work and to obtain auxiliary information we used satellite data from Envisat and ALOS in various imaging modes and geometries. Information on snow properties was obtained from snow pit measurements and ice core drilling. Main results are a sea ice thickness map for the McMurdo Sound, 3D information on snow in the percolation and dry snow zone, and information on surface roughness. We present first results from our measurements on land and sea ice properties and compare these results to satellite signatures from spaceborne sensors.

  1. 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.

  2. 3, 9991020, 2007 Summer sea ice

    E-print Network

    Boyer, Edmond

    CPD 3, 999­1020, 2007 Summer sea ice during the early Holocene H. Goosse et al. Title Page Abstract on the early Holocene climate constrains the summer sea ice projections for the 21st century H. Goosse, E #12;CPD 3, 999­1020, 2007 Summer sea ice during the early Holocene H. Goosse et al. Title Page

  3. Arctic Sea Ice Extent Plummets in 2007

    Microsoft Academic Search

    Julienne Stroeve; Mark Serreze; Sheldon Drobot; Shari Gearheard; Marika Holland; James Maslanik; Walt Meier; Ted Scambos

    2008-01-01

    Arctic sea ice declined rapidly to unprecedented low extents in the summer of 2007, raising concern that the Arctic may be on the verge of a fundamental transition toward a seasonal ice cover. Arctic sea ice extent typically attains a seasonal maximum in March and minimum in September. Over the course of the modern satellite record (1979 to present), sea

  4. 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

  5. Recent State of Arctic Sea Ice

    Microsoft Academic Search

    S. V. Nghiem; I. G. Rigor; P. Clemente-Colón; D. K. Perovich; J. A. Richter-Menge; Y. Chao; G. Neumann; M. Ortmeyer

    2008-01-01

    We present the recent state of Arctic sea ice including observations from 2008 in a context of a multi-decadal perspective. A new record has been set in the reduction of Arctic perennial sea ice extent this winter. As of 1 March 2008, the extent of perennial sea ice was reduced by one million km2 compared to that at the same

  6. Electromagnetic remote sensing of sea ice

    Microsoft Academic Search

    A. K. Jordan; M. E. Veysoglu

    1994-01-01

    Electromagnetic remote sensing of sea ice is viewed to introduce relevant practical problems to the inverse scattering community. A brief introduction to the importance of sea ice and sea ice physics is followed by a summary of direct scattering models where extensive references are given. Typical inverse problems and models that use these direct scattering models are discussed to provide

  7. 6, 1105111066, 2006 Sea ice, frost flowers

    E-print Network

    Paris-Sud XI, Université de

    ACPD 6, 11051­11066, 2006 Sea ice, frost flowers and halogen activation W. R. Simpson et al. Title Chemistry and Physics Discussions First-year sea-ice contact predicts bromine monoxide (BrO) levels better. Simpson (ffwrs@uaf.edu) 11051 #12;ACPD 6, 11051­11066, 2006 Sea ice, frost flowers and halogen activation

  8. Temporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica

    NASA Astrophysics Data System (ADS)

    Tison, J.-L.; Worby, A.; Delille, B.; Brabant, F.; Papadimitriou, S.; Thomas, D.; de Jong, J.; Lannuzel, D.; Haas, C.

    2008-04-01

    The evolution of the main physico-chemical properties of the unflooded 90-cm-thick first-year sea-ice cover at the Ice Station POLarstern (ISPOL) "clean site" is described. ISPOL was an international experiment of the German research icebreaker R.V. Polarstern. The vessel was anchored to an ice floe for an observation period of 5 weeks, during the early summer melt onset in the Western Weddell Sea. The "clean site" was specially designed and accessed so as to prevent any trace metal contamination of the sampling area. Observations were made at 5-day intervals during December 2004 in the central part of the main floe. Results show the succession of two contrasting phases in the behavior of the brine network (brine channels, pockets, and tubes). Initially, brine salinity was higher than that of sea-water, leading to brine migration and a decrease in the mean bulk salinity of the ice cover. This process is highly favored by the already high bulk porosity (14%), which ensures full connectivity of the brine network. Gravity drainage rather than convection seems to be the dominant brine transfer process. Half-way through the observation period, the brine salinity became lower than that of the sea-water throughout the ice column. The brine network therefore switched to a "stratified" regime in which exchange with sea-water was limited to molecular diffusion, strongly stabilizing the bulk mean sea-ice salinity. During the transition between the two regimes, and in areas closer to ridges, slush water (resulting from a mixture of snow meltwater and sea water accumulated at the snow-ice interface) penetrated through the growing "honeycomb-like structure" and replaced the downward draining brines. This resulted in a slight local replenishment of nutrients (as indicated by dissolved silicic acid). However, as a whole, the described decaying regime in this globally unflooded location with limited snow cover should be unfavorable to the development of healthy and active surface and internal microbial communities. The switch from gravity to diffusion controlled transport mechanisms within the ice column also should affect the efficiency of gas exchange across the sea-ice cover. The observed late build-up of a continuous, impermeable, superimposed ice layer should further significantly hamper gas exchange. Statistical estimates of the evolution of the ice thickness during the observation period and salinity trends of the under-ice water salinity down to 30 m corroborate model predictions of a moderate bottom melting (5-10 cm) from ocean heat fluxes.

  9. 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.

  10. Can Arctic Sea Ice Summer Melt be Accelerated by Changes in Spring Cloud Properties?

    Microsoft Academic Search

    I. Gorodetskaya; B. Tremblay; B. Liepert; M. Cane

    2006-01-01

    Ice-albedo feedback remains the major factor accelerating recently observed decline in the Arctic sea ice extent and thickness. The immediate effect of this feedback is offset by clouds, which decrease the amount of solar radiation reaching the surface in summer. However, once the surface albedo is decreased due to an increase in the open water fraction or enhanced snow melt,

  11. Additions to the public archive of submarine-based measurements of sea-ice draft

    Microsoft Academic Search

    D. A. Rothrock; M. R. Wensnahan; D. L. Bentley; F. Fetterer

    2006-01-01

    For over 45 years the US Navy has acquired data on Arctic sea-ice draft using upward looking sonar. For some time draft data declassified by the US Navy have been available at National Snow and Ice Data Center (NSIDC) spanning the years 1986 to 1998 with a small amount of supplemental data from 1976. These records come from data originally

  12. Field spectral signatures of snow, ice, and water

    Microsoft Academic Search

    Melvin B. Satterwhite; Herbert J. Mitchell; Terrence Hemmer; Joseph D. Leckie

    2003-01-01

    Spectra were taken that describes free water, ice, and snow, and vegetation and inorganic backgrounds. The reflectance of water films, ranging from 0.008 to 5.35 mm, on a spectralon background varied with water depth and the water transmittance and absorbtance properties. Thin water films, > 3.5 mm, quenched the short wave infrared (SWIR) reflectance, even though moderate visible-near infrared reflectance

  13. 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...

  14. National Snow and Ice Data Center: Antarctic Data Management Support

    NASA Astrophysics Data System (ADS)

    Bauer, R.; Scambos, T.; Scharfen, G.; Judy, C.

    2005-12-01

    The National Snow and Ice Data Center (NSIDC) operates two Antarctic data management projects for the National Science Foundation's Office of Polar Programs (OPP). The U.S. Antarctic Glaciological Data Center (AGDC) provides data management for the U.S. Antarctic Glaciological Program and related cryospheric science investigations. AGDC archives and distributes physical and geochemical data from ice cores, ice surface elevations, ice thickness, and bedrock topography, snow accumulation data and 10-meter temperatures, ice velocity measurements from remote sensing imagery and field survey data. The U.S. Antarctic Data Coordination Center (USADCC) provides a U.S. focus for the development of data set descriptions (metadata in the form of Directory Interchange Format entries) for the Antarctic Master Directory (AMD). The AMD contains more than 3000 data set descriptions submitted by 22 countries with Antarctic science programs. The USADCC provides access to easy to use web based tools to create metadata, and can advise investigators on compliance with the OPP Guidelines and Award Conditions for Scientific Data.

  15. 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.

  16. Greenland Ice Sheet Mass Balance Reconstruction. Part I: Net Snow Accumulation (16002009)

    E-print Network

    Howat, Ian M.

    question is whether the Greenland ice sheet is accumulating more snow due to climate warming. Greenland iceGreenland Ice Sheet Mass Balance Reconstruction. Part I: Net Snow Accumulation (1600­2009) JASON E, Denmark ** Desert Research Institute, Reno, Nevada (Manuscript received 20 June 2012, in final form 14

  17. Conjunctive Radar and Laser Altimetry Data Processing to Measure Snow Thickness

    Microsoft Academic Search

    Deepthi Puthalapat; Carl Leuschen; Thorsten Markus; Donald Cavalieri; William Krabill; John Sonntag; Matthew Sturm; James Maslanik

    2008-01-01

    Snow cover on sea ice plays an important role in the climate of the Polar Regions. Snow on sea ice reduces the heat exchange between the ocean and the atmosphere. The high albedo of snow increases the solar energy that is reflected back into the atmosphere, and the low thermal conductivity better isolates the interaction between the sea ice and

  18. 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.

  19. 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.

  20. 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.

  1. 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).

  2. Antarctic Sea Ice in the IPY

    Microsoft Academic Search

    S. F. Ackley; D. K. Perovich; C. A. Geiger

    2003-01-01

    Antarctic Sea Ice covers an area of 20 million km2 at maximum extent and therefore represents an areal coverage larger than either the Arctic ice cover or the Antarctic continent. Studies of Antarctic sea ice in the modern era were only initiated well after the IGY, with the advent of passive microwave satellite coverage in 1973, followed by the use

  3. Ice Sheets and Sea Level

    NSDL National Science Digital Library

    In this exercise, learners use basic arithmetic to determine the amount that sea level would rise around the globe with the melting of the Greenland and Antarctic ice sheets. Basic data for this calculation is provided. This resource is from PUMAS - Practical Uses of Math and Science - a collection of brief examples created by scientists and engineers showing how math and science topics taught in K-12 classes have real world applications.

  4. The Thickness Distribution of Sea Ice

    Microsoft Academic Search

    A. S. Thorndike; D. A. Rothrock; G. A. Maykut; R. Colony

    1975-01-01

    The polar oceans contain sea ice of many thicknesses ranging from open water to thick pressure ridges. Since many of the physical properties of the ice depend upon its thickness, it is natural to expect its largescale geophysical properties to depend on the relative abundance of the various ice types. The ice pack is treated as a mixture whose constituents

  5. 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.

  6. Halocarbons associated with Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Atkinson, Helen M.; Hughes, Claire; Shaw, Marvin J.; Roscoe, Howard K.; Carpenter, Lucy J.; Liss, Peter S.

    2014-10-01

    Short-lived halocarbons were measured in Arctic sea-ice brine, seawater and air above the Greenland and Norwegian seas (~81°N, 2-5°E) in mid-summer, from a melting ice floe at the edge of the ice pack. In the ice floe, concentrations of C2H5I, 2-C3H7I and CH2Br2 showed significant enhancement in the sea ice brine, of average factors of 1.7, 1.4 and 2.5 times respectively, compared to the water underneath and after normalising to brine volume. Concentrations of mono-iodocarbons in air are the highest ever reported, and our calculations suggest increased fluxes of halocarbons to the atmosphere may result from their sea-ice enhancement. Some halocarbons were also measured in ice of the sub-Arctic in Hudson Bay (~55°N, 77°W) in early spring, ice that was thicker, colder and less porous than the Arctic ice in summer, and in which the halocarbons were concentrated to values over 10 times larger than in the Arctic ice when normalised to brine volume. Concentrations in the Arctic ice were similar to those in Antarctic sea ice that was similarly warm and porous. As climate warms and Arctic sea ice becomes more like that of the Antarctic, our results lead us to expect the production of iodocarbons and so of reactive iodine gases to increase.

  7. 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.

  8. Annual cycle of landfast sea ice in Prydz Bay, east Antarctica

    NASA Astrophysics Data System (ADS)

    Lei, Ruibo; Li, Zhijun; Cheng, Bin; Zhang, Zhanhai; Heil, Petra

    2010-02-01

    Under the Chinese National Antarctic Research Expedition program in 2006, the annual thermal mass balance of landfast ice in the vicinity of Zhongshan Station, Prydz Bay, east Antarctica, was investigated. Sea ice formed from mid-February onward, and maximum ice thickness occurred in late November. Snow cover remained thin, and blowing snow caused frequent redistribution of the snow. The vertical ice salinity showed a "question-mark-shaped" profile for most of the ice growth season, which only turned into an "I-shaped" profile after the onset of ice melt. The oceanic heat flux as estimated from a flux balance at ice-ocean interface using internal ice temperatures decreased from 11.8 (±3.5) W m-2 in April to an annual minimum of 1.9 (±2.4) W m-2 in September. It remained low through late November, in mid-December it increased sharply to about 20.0 W m-2. Simulations applying the modified versions of Stefan's law, taking account the oceanic heat flux and ice-atmosphere coupling, compare well with observed ice growth. There was no obvious seasonal cycle for the thermal conductivity of snow cover, which was also derived from internal ice temperatures. Its annual mean was 0.20 (±0.04) W m-1 °C-1.

  9. 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....

  10. 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.

  11. Monitoring Land-fast Sea Ice in the Western Antarctic Through Multi-sensor Data Fusion

    NASA Astrophysics Data System (ADS)

    Kim, M.; Im, J.; Kim, J. W.; Lee, S.; Shin, M.

    2014-12-01

    Land-fast sea ice is almost motionless and fixed to shorelines, contrary to pack ice floating on the sea. As the spatiotemporal distribution of land-fast sea ice is closely related to the global and polar climate systems, it is crucial to accurately monitor land-fast sea ice to better understand the climate systems. Remote sensing can be used to monitor land-fast sea ice as it provides data covering vast areas at high temporal resolution. While remote sensing-based land-fast sea ice monitoring has been investigated in the Arctic areas, very few studies were conducted over the Antarctic areas. In particular, no studies have been conducted in the western Antarctic due to much greater variability of sea ice and more complex topography than the eastern Antarctic. The purpose of this study was to develop an automated land-fast sea ice monitoring approach using multi-sensor data fusion and machine learning approaches in the entire Antarctic especially focusing on the western part. The basic assumptions of land-fast sea ice with almost 100% of sea ice concentration and almost 0 m/s of sea ice velocity were used. Based on these assumptions, a total of 11 variables including sea ice concentration, 8 dual polarization frequency channels from The Advanced Microwave Scanning Radiometer for EOS (AMSR-E), ice surface temperature from visible/TIR sensor such as the MODerate resolution Imaging Spectroradiometer (MODIS) and ice velocity from Special Sensor Microwave/Imager (SSM/I) were used to identify land-fast sea ice. In addition to the 11 remote sensing-based variables, previous land-fast sea ice results visually identified using MODIS data by Fraser in the eastern Antarctic were used as reference data. Two rule-based machine learning approaches including See5.0 and random forest were used to map land-fast sea ice. Long-term temporal changes of the Antarctic land-fast sea ice distribution were analyzed during the period of 2000 to 2008 at multiple time scales. National Snow & Ice Data Center (NSIDC)-provided 250m MODIS Antarctic ice shelf images and high resolution Synthetic Aperture Radar (SAR) data (Radarsat 2) were used to validate the spatial distribution of the predicted land-fast sea ice.

  12. 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.

  13. 4, 107128, 2007 Sea-ice-drift

    E-print Network

    Paris-Sud XI, Université de

    OSD 4, 107­128, 2007 Sea-ice-drift dynamics and pack fracture A. Chmel et al. Title Page Abstract aspects of the sea-ice-drift dynamics and pack fracture A. Chmel 1 , V. N. Smirnov 2 , and L. V. Panov 2 1 to: A. Chmel (chmel@mail.ioffe.ru) 107 #12;OSD 4, 107­128, 2007 Sea-ice-drift dynamics and pack

  14. Sea ice's effect on oceanic deepwater

    NSDL National Science Digital Library

    Yoshiki Komuro

    A coupled sea ice-ocean model of the Southern Ocean was used to analyze the effects of sea ice on dense, cold deepwater formation. It was found that this model can more accurately project the amount of freshwater entering the oceans from sea ice, which may help researchers better estimate ocean circulation patterns and produce more accurate climate estimates based on the ocean's salinity.

  15. Variability and Trends in Sea Ice Extent and Ice Production in the Ross Sea

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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 sq km/yr. For a characteristic ice thickness of 0.6 m, this yields a volume transport of about 20 cu km/yr, 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.

  16. C-band radar backscatter of sea ice in the Weddell Sea, Antarctica during the austral winter of 1992

    NASA Technical Reports Server (NTRS)

    Hosseinmostafa, R.; Drinkwater, Mark R.; Gogineni, S. P.; Dierking, W.

    1993-01-01

    A C-band ship-based scatterometer was used to measure the backscatter coefficient of sea ice in the Weddell Sea during June and July 1992. These are the first microwave scatterometer data ever to be collected in the Antarctic sea ice cover during the austral winter. The instrument was a frequency-modulated continuous-wave (FM-CW) radar altimeter modified by the University of Kansas Radar Systems and Remote Sensing Laboratory to perform backscatter measurements. Measurements were taken as part of a Jet Propulsion Laboratory experiment aboard the German ice research vessel F.S. Polarstern. Backscatter measurements were performed at incidence angles ranging from 17 to 65 degrees with VV and HV polarization as the Polarstern travelled from east to west across the central Weddell Sea. Backscatter measurements were made of several different types of ice sea including pancake, dark nilas, white nilas, grey, first-year and second-year ice. Periodic external calibrations were performed with the aid of a Luneberg Lens to enable absolute values of backscatter to be derived from the data. At each radar measurement location, in-situ measurements were made of snow and sea ice. Physical and chemical analyses of ice core and snow samples, together with high magnification photography of snow crystallography provide important information with which to develop physical models of the scattering systems. Meteorological information and oceanographic conditions were also recorded throughout the experiment. Many of the stations were chosen to coincide with periods of near-simultaneous or coincident imaging by the ERS-1 satellite Synthetic Aperture Radar (SAR). This enabled spaceborne imaging by the C-band SAR of areas of sea ice in which backscatter measurements were taken. This provides a valuable tool for interpretation of satellite SAR imagery from Antarctic sea ice in terms of the physical properties of the sea ice and snow. Preliminary results of the backscatter from the various ice types and their relation to the physical properties of sea ice are presented.

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

    NASA Astrophysics Data System (ADS)

    McAllister, M.; Booker, L.; Fowler, D. K.; Haran, T. M.

    2014-12-01

    For close to 15 years, the National Snow and Ice Data Center (NSIDC) NASA Distributed Active Archive Center (NDAAC) 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 snow and sea ice data products relevant to cryospheric science. NSIDC offers a variety of methods for obtaining these data. Users can ftp data directly from an online archive which allows for a very quick download. The Reverb Search & Order Tool contains a complete set of metadata for all products which can be searched for and ordered. Reverb 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, a number of tools have been developed to assist with browsing, editing, reprojection, resampling, and format conversion. One such service, Data Access, can be accessed through Reverb and performs subsetting, reformatting, and reprojection. This service can also be accessed via an Application Programming Interface (API) from a user-written client. Other tools include the 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 also created the MIST to 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. Tools from other sources include HDFView from the National Center for Supercomputing Applications (NCSA), and the MODIS Reprojection Tool (MRT) and MRT Swath developed by the Land Processes DAAC (LP-DAAC).

  18. 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

  19. A Multi-Disciplinary Sea Ice Ontology

    NASA Astrophysics Data System (ADS)

    Khalsa, S. S.; Parsons, M. A.; Duerr, R. E.; Pulsifer, P. L.; McGuinness, D. L.; Fox, P. A.; McCusker, J.

    2011-12-01

    Sea ice is a central element of the Arctic system and a strong indicator of high-latitude climate change. In addition to the many scientific disciplines in which sea ice is of importance, the domains of transportation, defense, natural resources and human settlements all have interests in and contribute to the body of knowledge regarding sea ice. To help advance the interdisciplinary understanding and usability of sea ice data we have developed a preliminary sea ice ontology. This effort began with a workshop in which sea ice modelers, field researchers, remote sensing scientists and operational forecasters described the facets of sea ice from the perspective of their respective disciplines. We will describe the features of this ontology and highlight some of the challenges we encountered in building it. We will also describe our plans to incorporate indigenous sea ice knowledge, map some existing sea ice data sets using the ontology, and to link the ontology to relevant marine, polar, atmospheric, and global ontologies and semantic services.

  20. Ice, Cloud, and land Elevation (ICESat) satellite Data Management and Delivery at the National Snow and Ice Data Center

    NASA Astrophysics Data System (ADS)

    Fowler, D.; Korn, D.

    2006-12-01

    The Geoscience Laser Altimeter System (GLAS) instrument aboard the Ice, Cloud, and land Elevation (ICESat) satellite launched on 12 January 2003. The primary objective of the ICESat mission is to provide global measurements of polar ice sheet elevation to discern changes in ice volume (mass balance) over time. Secondary objectives of the mission are to measure sea ice roughness and thickness, cloud and atmospheric properties, land topography, vegetation canopy heights, ocean surface topography, and surface reflectivity. The GLAS instrument has three lasers, each of which has a 1064 nm laser channel for surface altimetry and dense cloud heights, and a 532 nm lidar channel for the vertical distribution of clouds and aerosols. Here, we present a description of the data flow through NASA's EOSDIS Core System (ECS) and how users gain access to the data. National Snow and Ice Data Center (NSIDC) at the University of Colorado, Boulder is the primary ECS center for archiving and distributing GLAS data to researchers. To fulfill the above objectives, GLAS data can be requested in a variety of methods including an online Data Pool, several search and order tools, and a spatial subsetting option. This poster will describe these methods. Multiple releases of the ICESat/GLAS data are now available at NSIDC (http://nsidc.org/data/icesat/).

  1. Characterization of ice binding proteins from sea ice algae.

    PubMed

    Bayer-Giraldi, Maddalena; Jin, EonSeon; Wilson, Peter W

    2014-01-01

    Several polar microalgae are able to live and thrive in the extreme environment found within sea ice, where growing ice crystals may cause mechanical damage to the cells and reduce the organisms' living space. Among the strategies adopted by these organisms to cope with the harsh conditions in their environment, ice binding proteins (IBPs) seem to play a key role and possibly contribute to their success in sea ice. IBPs have the ability to control ice crystal growth. In nature they are widespread among sea ice microalgae, and their mechanism of function is of interest for manifold potential applications. Here we describe methods for a classical determination of the IBP activity (thermal hysteresis, recrystallization inhibition) and further methods for protein characterization (ice pitting assay, determination of the nucleating temperature). PMID:24852640

  2. Earth Exploration Toolbook Chapter: Whither Arctic Sea Ice?

    NSDL National Science Digital Library

    Betsy Youngman

    DATA: Sea Ice Images TOOLS: ImageJ, Spreadsheet application SUMMARY: Animate 30 years of sea ice images and measure the ice extent each year to produce a graph. Compare the ice extents to air temperatures.

  3. Simulated climate change effects on ice and snow covers on lakes in a temperate region

    Microsoft Academic Search

    Heinz G. Stefan; Xing Fang

    1997-01-01

    A simulation model for ice and snow covers is applied to dimictic and polymictic lakes of the temperate zone to project the effects of possible climate warming on ice and snow covers. The winter cover model is associated with a deterministic, one-dimensional water temperature model. The lake parameters required as model input are surface area (AS), maximum depth (Hmax), summer

  4. A methodology to eliminate snow-and ice-contaminated solutions from GPS coordinate time series

    E-print Network

    Larson, Kristine

    A methodology to eliminate snow- and ice-contaminated solutions from GPS coordinate time series by snow or ice. This information is then used to remove outliers in GPS coordinate time series. The signal network. The algorithm improves the precision of ~10% of these coordinate time series, with most

  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 of Bayes detection to produce sea ice extent maps. Statistical models for sea ice and ocean are represented

  6. Springtime atmospheric transport controls Arctic summer sea-ice extent

    NASA Astrophysics Data System (ADS)

    Kapsch, Marie; Graversen, Rune; Tjernström, Michael

    2013-04-01

    The sea-ice extent in the Arctic has been steadily decreasing during the satellite remote sensing era, 1979 to present, with the highest rate of retreat found in September. Contributing factors causing the ice retreat are among others: changes in surface air temperature (SAT; Lindsay and Zhang, 2005), ice circulation in response to winds/pressure patterns (Overland et al., 2008) and ocean currents (Comiso et al., 2008), as well as changes in radiative fluxes (e.g. due to changes in cloud cover; Francis and Hunter, 2006; Maksimovich and Vihma, 2012) and ocean conditions. However, large interannual variability is superimposed onto the declining trend - the ice extent by the end of the summer varies by several million square kilometer between successive years (Serreze et al., 2007). But what are the processes causing the year-to-year ice variability? A comparison of years with an anomalously large September sea-ice extent (HIYs - high ice years) with years showing an anomalously small ice extent (LIYs - low ice years) reveals that the ice variability is most pronounced in the Arctic Ocean north of Siberia (which became almost entirely ice free in September of 2007 and 2012). Significant ice-concentration anomalies of up to 30% are observed for LIYs and HIYs in this area. Focusing on this area we find that the greenhouse effect associated with clouds and water-vapor in spring is crucial for the development of the sea ice during the subsequent months. In years where the end-of-summer sea-ice extent is well below normal, a significantly enhanced transport of humid air is evident during spring into the region where the ice retreat is encountered. The anomalous convergence of humidity increases the cloudiness, resulting in an enhancement of the greenhouse effect. As a result, downward longwave radiation at the surface is larger than usual. In mid May, when the ice anomaly begins to appear and the surface albedo therefore becomes anomalously low, the net shortwave radiation anomaly becomes positive. The net shortwave radiation contributes during the rest of the melting season to an enhanced energy flux towards the surface. These findings lead to the conclusion that enhanced longwave radiation associated with positive humidity and cloud anomalies during spring plays a significant role in initiating the summer ice melt, whereas shortwave-radiation anomalies act as an amplifying feedback once the melt has started. References: Lindsay, R. and J. Zhang. The thinning of Arctic Sea Ice, 19882003: Have We Passed a Tipping Point?. J. Clim. 18, 48794894 (2005). Overland, J. E., M. Wang and S. Salo. The recent Arctic warm period. Tellus 60A, 589-597 (2008). Comiso, J. C., C. L. Parkinson, R. Gersten and L. Stock. Accelerated Decline in the Arctic sea ice cover. Geophys. Res. Lett. 35, L01703 (2008). Francis, J. A. and E. Hunter. New Insight Into the Disappearing Arctic Sea Ice. EOS T. Am. Geophys. Un. 87, 509511 (2006). Maksimovich, E. and T. Vihma. The effect of heat fluxes on interannual variability in the spring onset of snow melt in the central Arctic Ocean. J. Geophys. Res. 117, C07012 (2012). Serreze, M. C., M. M. Holland and J. Stroeve. Perspectives on the Arctic's Shrinking Sea-Ice Cover. Science 315, 1533-1536 (2007).

  7. 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.

  8. Recent State of Arctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Nghiem, S. V.; Rigor, I. G.; Clemente-Colón, P.; Perovich, D. K.; Richter-Menge, J. A.; Chao, Y.; Neumann, G.; Ortmeyer, M.

    2008-12-01

    We present the recent state of Arctic sea ice including observations from 2008 in a context of a multi-decadal perspective. A new record has been set in the reduction of Arctic perennial sea ice extent this winter. As of 1 March 2008, the extent of perennial sea ice was reduced by one million km2 compared to that at the same time last year as observed by the NASA SeaWinds scatterometer on the QuikSCAT satellite (QSCAT). This decrease of perennial ice continues the precipitous declining trend observed in this decade. Furthermore, the perennial sea ice pattern change was deduced by buoy-based estimates with 50 years of data from drifting buoys and measurement camps to track sea ice movement around the Arctic Ocean. The combination of the satellite and surface data records confirms that the reduction of winter perennial ice extent broke the record in 2008 compared to data over the last half century. In the winter, the loss of perennial ice extent was driven by winds that compressed the ice and transported it out of the Fram Strait and Nares Strait to warmer ocean waters at lower latitudes, where the ice melted very effectively. Another historical fact is that the boundary of perennial sea ice already crossed the North Pole (NP) in February 2008, leaving the area around the NP occupied by seasonal sea ice. This is the first time, not only from the satellite data record but also in the history of sea ice charting at the National Ice Center since the 1970's, that observations indicate the seasonal ice migration into the NP area so early in winter. In the Bering Sea by 12 March 2008, the sea ice edge reached to an extent that coincided with the continental shelf break, indicating bathymetric effects on the distribution of water masses along the Aleutian North Slope, Bering Slope, Anadyr, and Kamchatka Currents that governed the pattern of sea ice formation in this region. Moreover, QSCAT observations showed that, in the 2008 winter, seasonal ice occupied the Northern Sea Route, and most of two routes of the Northwest Passage, north and south of Victoria Island, which facilitated ice retreat and the opening of waterways this summer. Most importantly, the shift from a perennial to a seasonal ice covered Arctic Ocean significantly decreases the overall surface albedo resulting in enhanced solar heat absorption in spring and summer, which further decreases the Arctic ice pack through the ice albedo feedback mechanism. In early September 2008, a major melt event occurred over a large region extending from the Beaufort Sea across the Kara Sea toward the Laptev Sea, with active melt areas encroaching in the NP vicinity. This melt event was caused by an advection of warm air from the south, which melted and pushed sea ice away at the same time. At that time, the total extent of Arctic sea ice was about 0.5 million km2 (size of Spain) larger than that at the same time last year.

  9. Sea ice cover in the Caspian and Aral seas from active and passive satellite microwave data

    NASA Astrophysics Data System (ADS)

    Kouraev, A. V.; Papa, F.; Mognard, N. M.; Buharizin, P. I.; Cazenave, A.; Cretaux, J.-F.; Dozortseva, J.; Remy, F.

    2003-04-01

    Stable ice cover forms every year in the Caspian and Aral seas. Ice stays for several months and negatively affects navigation conditions, endangers constructions located on the coast and the oil rigs that have recently been installed in the shelf regions of the Northern Caspian by Russia and Kazakhstan. Ice extent varies significantly from year to year in response to changes in hydrometeorological conditions over the region and its variations may serve as an early indicator of the large-scale climate change. We studied ice cover in these two seas using data from the Topex-Poseidon satellite, operating since 1992. This platform has two nadir-looking instruments - a dual-frequency radar altimeter and a passive microwave radiometer. Five Topex-Poseidon passes covering the northern part of the Caspian sea and two passes covering the central part of the Big Aral sea, were selected, providing data for ten consecutive years with a 10 days repetitive period. The combination of both active (backscatter coefficient at 13 GHz) and passive (brightness temperature at 18 and 37 GHz) microwave measurements provides information to estimate ice concentration, roughness and height of snow cover on ice. This information on ice cover was complemented by passive microwave data from the SMMR (Scanning Multichannel Microwave Radiometer) instrument onboard the satellite NIMBUS-7 (since 1979) and the SSMI (Special Sensor Microwave Imager) instrument on board the DMSP (Defense Meteorological Satellite Program) series (since 1987). Analysis of time series of ice extent and types shows pronounced regional, seasonal and interannual variability. In the Northern Caspian sea ice cover has a maximum extent in the shallow and isolated eastern part, while in the western part presence of ice cover is reduced. Interannual variability of ice cover extent for ten selected years show a warming signal: ratio of presence of ice cover in observations in both Caspian and Aral seas is reduced (more than two times), especially during the four unusually mild winters (1998/99 to 2001/02). In the Caspian sea such dramatic reduction of ice extent affects breeding habits and living conditions of the Caspian seal - the only mammal in this sea.

  10. Temporal variations of the microwave signatures of sea ice during the late spring an early summer near Mould Bay NWT

    Microsoft Academic Search

    T. C. Grenfell; A. W. Lohanick

    1985-01-01

    A series of surface-based measurements of microwave brightness temperatures and accompanying ice characteristics have been made on first-year and multiyear sea ice in the Canadian archipelago and in the southeastern Beaufort Sea during the late spring and early summer of 1982. Radiometer data taken at frequencies of 10, 18.7, and 37 GHz show the transition from conditions of snow-covered ice

  11. Distinguishing Ice from Snow for Melt Modeling Using Daily Observations from MODIS

    NASA Astrophysics Data System (ADS)

    Rittger, K.; Brodzik, M. J.; Racoviteanu, A.; Barrett, A. P.; Khalsa, S. J. S.; Painter, T. H.; Armstrong, R. L.; Burgess, A. B.

    2014-12-01

    In Earth's mountainous regions, melt from both seasonal snow and glacier ice contributes to streamflow. Few in-situ observations exist that can help distinguish between the two components of melt, particularly across large mountain ranges. In this study, we analyze daily time series of MODIS data products to distinguish ice from snow as the seasonal snowpack recedes revealing firn and glacier ice surfaces. We run a temperature index melt model for the Hunza, a sub-basin of the Upper Indus basin using the MODIS data to discriminate between glacier ice and snow and partition the corresponding streamflow. During the ablation period, this high elevation mid-latitude snowpack receives intense incoming solar radiation resulting in snow grain growth and surface albedo decreases. To explore snow grain growth, we use estimates of grain size from both the MODIS Snow Covered Area and Grain Size Model (MODSCAG) and MODIS Dust Radiative Forcing in Snow (MODDRFS). To explore albedo reduction we use 2 standard albedo products from MODIS, the Terra Daily Snow Cover algorithm (MOD10A1) and Surface Reflectance BRDF/Albedo (MOD43). We use a threshold on the grain size and albedo products to discriminate ice from snow. We test the ability of the 4 MODIS products to discriminate snow from glacier ice using higher resolution data from the Landsat 8 sensor from July 5th and July 21st, 2013 for a subset of the study area in the Karakoram region of the Himalaya that includes the Yazghil and Hopper Glaciers that drain north and northeast in the Shimshall Valley, part of the Hunza River basin. Snow and glacier ice are mapped using band ratio techniques, and are then separated on the basis of broadband albedo values calculated from Landsat bands for comparison with MODIS-derived snow and glacier ice pixels. We run a temperature index melt model that uses gap filled snow covered area from MODSCAG and interpolated station temperature data for the Hunza River basin. The model outputs daily melt volume from three surface classifications: area of snow over land, snow over glacier ice, and exposed glacier ice. The partitioning is done using a combination of MODICE and 1 of 4 MODIS products. Melt from glacier ice accounts for 25% of the combined melt on average across the 4 MODIS products for the Hunza basin, with fluctuations based on the seasonal variability of snowfall.

  12. The secret of the Svalbard sea ice barrier

    Microsoft Academic Search

    S. V. Nghiem; M. L. Van Woert; G. Neumann

    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 a significant navigational hazard. The secret of this sea ice formation lies in the bottom bathymetry, which governs the distribution of cold Arctic waters masses and sea ice growth

  13. The convective desalination of sea ice

    E-print Network

    Rees Jones, David

    2014-07-01

    provided by the department and my college, Christ’s. The breath of God produces ice, and the broad waters become frozen. (Job 37:10) Contents Contents ix 1 Overview 1 2 Sea-Ice Modelling 7 2.1 Sea ice and the polar climate... components of the physical climate system. Evolving in space and time, sea ice has thermal and mechanical properties that must be updated dynamically for a faithful representation within climate models. Such models are vital tools to help people everywhere...

  14. Arctic Sea Ice Deformation in Satellite Remote Sensing Data and in a Coupled Sea Ice-Ocean Model

    Microsoft Academic Search

    G. Spreen; R. Kwok; D. Menemenlis; A. T. Nguyen

    2010-01-01

    Sea ice movement is driven by surface wind and ocean currents. The spatial inhomogeneity of these forces causes internal sea ice stress gradients, which eventually cause ice to ridge or break up. This sea ice deformation is an important process for (1) the sea ice mass balance, (2) brine rejection into the ocean, (3) regulation of ocean-to-air heat and gas

  15. Ridged sea ice characteristics in the Arctic from a coupled multicategory sea ice model

    NASA Astrophysics Data System (ADS)

    MâRtensson, S.; Meier, H. E. M.; Pemberton, P.; Haapala, J.

    2012-04-01

    In this study, a multicategory sea ice model with explicit ice classes for ridged and rafted ice was used to examine the evolution of deformed ice during the period 1980-2002. The results show that (1) ridged ice comprises roughly 45-60% of Arctic sea ice volume and 25-45% of the sea ice area, (2) most of the perennial ice consists of ridged ice, and (3) ridged ice exhibits a small seasonal variability. Our results also show an increase in mean ridged ice thickness of 4-6 cm yr-1 during the summer in an area north of the Canadian Archipelago and a corresponding decrease in the East Siberian Sea and Nansen Basin. At the same time, Arctic sea ice age has been observed to decline and ice drift speed to increase during the simulation period. We connect these findings with a modeled regional increase in the production rate of ridged ice. Comparison of the multicategory model and a two category reference model shows a substantially increased ice production rate due to a more frequent occurrence of leads, resulting in an ice thickness increase of up to 0.8 m. Differences in ice physics between the multicategory and reference models also affect the freshwater content. The sum of liquid and solid freshwater content in the entire Arctic Ocean is about 10% lower and net precipitation (P-E) is about 7% lower as compared to the reference model.

  16. Antarctic sea ice thickness affects algae populations

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2013-01-01

    In the waters off Antarctica, algae grow and live in the sea ice that surrounds the southern continent—a floating habitat sure to change as the planet warms. As with most aquatic ecosystems, microscopic algae form the base of the Southern Ocean food web. Distinct algae populations reside in the sea ice surface layers, on the ice's underside, and within the floating ice itself. The algae that reside on the floating ice's underside are particularly important for the region's krill population, while those on the interior or surface layers are less accessible. Understanding how changing sea ice properties will affect the regional biology, then, depends on understanding how algae populations interact with the ice.

  17. Black carbon in Arctic snow and its effect on surface albedo

    E-print Network

    #12;8 Tundra of northern Yakutia, April 2008 #12;9 Tundra of northern Yakutia, April 2008 A surface and in boreal forest) Arctic snow - Tundra in spring - Sea ice in spring (covered with snow) - Greenland Ice

  18. Probabilistic Forecasting of Arctic Sea Ice Extent

    NASA Astrophysics Data System (ADS)

    Slater, A. G.

    2013-12-01

    Sea ice in the Arctic is changing rapidly. Most noticeable has been the series of record, or near-record, annual minimums in sea ice extent in the past six years. The changing regime of sea ice has prompted much interest in seasonal prediction of sea ice extent, particularly as opportunities for Arctic shipping and resource exploration or extraction increase. This study presents a daily sea ice extent probabilistic forecast method with a 50-day lead time. A base projection is made from historical data and near-real-time sea ice concentration is assimilated on the issue date of the forecast. When considering the September mean ice extent for the period 1995-2012, the performance of the 50-day lead time forecast is very good: correlation=0.94, Bias = 0.14 ×106 km^2 and RMSE = 0.36 ×106 km^2. Forecasts for the daily minimum contains equal skill levels. The system is highly competitive with any of the SEARCH Sea Ice Outlook estimates. The primary finding of this study is that large amounts of forecast skill can be gained from knowledge of the initial conditions of concentration (perhaps more than previously thought). Given the simplicity of the forecast model, improved skill should be available from system refinement and with suitable proxies for large scale atmosphere and ocean circulation.

  19. NOx emission from surface snow and ice over Tibetan Plateau, China

    NASA Astrophysics Data System (ADS)

    Wang, J.; Zhu, T.; Lin, W.; Wang, F.

    2010-12-01

    Photochemical reactions on the surface of snow and ice have been proved to be an important NOx source in the polar boundary layer. The exchanges of NOx between snow and air have significant impacts on the atmospheric components and photochemical processes in the overlying boundary layer, which can increase the oxidizing capacity and may impact on the environmental records that are retrieved from ice cores. The Tibetan Plateau (TP) is the main snow-covered area in the mid-latitudes of northern hemisphere. Different from the Arctic and Antarctic, TP has strong UV radiation on the surface of snow and ice due to its high altitude and the large area of snow and glaciers. With four field measurements in July 1st Glacier, Mount Everest Area, Yulong Snow Mountain, and Tianshan NO.1 Glacier, we obtained observational evidences on the release of NOx from surface snow and ice over Tibetan Plateau. The average NOx concentration during daytime was 1-5 ppbv, this is much higher than that in Arctic and Antarctic (pptv level). Besides the photochemical reaction and transfer process within snow/ice, factors such as UV radiation intensity, temperature, snow characteristics and mountain-valley winds all affect NOx release processes from those snow covered areas. The NOx fluxes during daytime in Yulong Snow Mountain and Tianshan NO.1 Glacier were about 10-45nmol m-2 h-1, this is similar as those observed in Arctic and Antarctic (15-40 nmol m-2 h-1). The contribution of NOx emission from snow/ice over Tibetan Plateau to the atmosphere oxidizing capacity needs more research.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Seasonal and interannual pollen variability in snow layers of arctic ice caps

    Microsoft Academic Search

    Jocelyne C. Bourgeois

    2000-01-01

    The pollen content of snow, deposited at the summit of three ice caps and a small glacier in the Canadian Arctic and at one ice cap in the Russian Arctic, was determined for periods ranging from one to 13 years. On the ice caps, boreal forest trees and low arctic shrubs account, on average, for 26% to 49% of the

  5. 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.

  6. Modelling of melt ponds on a sea ice floe

    Microsoft Academic Search

    F. Scott; D. Feltham

    2009-01-01

    During winter the ocean surface at the poles freezes over to form sea ice. Sea ice floats on the ocean surface and has a matrix structure caused by the rejection of salts during freezing. In the summer sea ice melts at its surface creating melt ponds. An accurate estimate of the fraction of the upper sea-ice surface covered in melt

  7. Controls on Arctic Sea Ice Strength: Constraints from Geophysical Observations.

    E-print Network

    Heaton, Thomas H.

    Controls on Arctic Sea Ice Strength: Constraints from Geophysical Observations. Sea ice exhibits and the ocean, the "sea ice system" exhibits a dynamical behavior that has both fluid and solid properties. Interestingly, some features of sea ice are similar to those observed for the Earth's crust. Fractures spanning

  8. JET FORMATION AT THE SEA ICE EDGE HAROLD DBS HEORTON

    E-print Network

    Crawford, Ian

    JET FORMATION AT THE SEA ICE EDGE HAROLD DBS HEORTON UCL PhD January 2013 1 #12;I, Harold Heorton flowing under, a compacted sea ice edge. Sea ice edge jets have been observed (Johannessen et al. 1983). This thesis presents a study of a dynamic sea ice edge responding to atmospheric and oceanic jet formation

  9. Influence of the Gulf Stream on the Barents Sea ice retreat and Eurasian coldness

    NASA Astrophysics Data System (ADS)

    Sato, Kazutoshi; Inoue, Jun; Watanabe, Masahiro

    2014-05-01

    Abnormal winter sea-ice retreat over the Barents Sea has been considered as a leading clue to the recent midlatitude severe winters. Barents Sea is considered as a hot spot for the rapid Arctic climate change due to the intense air-sea interaction induced by the sea-ice decrease; however, the underlying mechanisms remain uncertain, in particular causal relation of sea-ice retreat and atmospheric forcing and response. To understand this causality, we selected typical cases, defined as averaged warm and averaged cold years of December using the NCEP Climate Forecast System Reanalysis (CFSR). The composite analysis, revealed that anticyclonic anomaly is obvious over the northwestern Eurasia. The western Barents Sea and Sbarvard locates at the strong pressure gradient zone, prevailing southerly winds. Over the Barents Sea, the difference in daily mean air temperature between warm and cold winters is more than 10°, suggesting that warm advection prevails during warm years. Therefore, during warm years, decrease in sea-ice cover is induced by southerly warm advection. The positive anomalies of precipitation from the southeast of Greenland to Barents Sea and negative anomalies of them from Nordic Sea to western Eurasia means the poleward shift of cyclone tracks, suggesting that the moisture transport is also changed poleward. Because the cyclones tend to shift poleward in less sea ice year over the Barents Sea, it is natural that the snow depth over the sea ice near the Fram Strait shows a positive anomaly during warm winters. Here we show that the poleward shift of sea surface temperature over the Gulf Stream, where is situated upstream from the Barents Sea, modifies the horizontal distribution of tropospheric condensational heating resulted from change in convection over the warm current, likely acting as a bridge to the Barents Sea by forcing planetary waves. This remote atmospheric response modifies cyclone tracks poleward, resulting in anomalous warm advection over the Barents Sea sector.

  10. Optimization of a Sea Ice Model Using Basinwide Observations of Arctic Sea Ice Thickness, Extent, and Velocity

    E-print Network

    Feltham, Daniel

    Optimization of a Sea Ice Model Using Basinwide Observations of Arctic Sea Ice Thickness, Extent 2004, in final form 27 June 2005) ABSTRACT A stand-alone sea ice model is tuned and validated using satellite-derived, basinwide observations of sea ice thickness, extent, and velocity from the years 1993

  11. Comparing Arctic Sea Ice Kinematics from Satellite Remote Sensing Data to Coupled Sea Ice-Ocean Model Results

    Microsoft Academic Search

    G. Spreen; D. Menemenlis; R. Kwok; A. T. Nguyen

    2009-01-01

    The Arctic sea ice in many respects is an important component of the Earth's climate system, e.g., sea ice governs the ocean to atmosphere heat flux, freezing and melting influences the upper ocean salinity and density, and sea ice dynamics act as a latent energy transport. During recent years substantial changes of the Arctic sea ice cover have been observed.

  12. Radar scattering from snow facies of the Greenland ice sheet: results from the AIRSAR 1991 campaign

    Microsoft Academic Search

    E. Rignot; K. Jezek; J. J. van Zyl; M. R. Drinkwater; Y. L. Lou

    1993-01-01

    In June 1991, the NASA\\/Jet Propulsion Laboratory airborne SAR (AIRSAR) collected the first calibrated multi-channel SAR observations of the Greenland ice sheet. Large changes in radar scattering are detected across different melting zones. In the dry-snow zone, Rayleigh scattering from small snow grains dominates at C-band. In the soaked-snow zone, surface scattering dominates, and an inversion technique was developed to

  13. Measuring the sea ice floe size distribution

    NASA Technical Reports Server (NTRS)

    Rothrock, D. A.; Thorndike, A. S.

    1984-01-01

    The sea ice covering the Arctic Ocean is broken into distinct pieces,called floes. In the summer, these floes, which have diameters ranging up to 100 km, are separated from each other by a region of open water. In the winter, floes still exist, but they are less easily identified. An understanding of the geometry of the ice pack is of interest for a number of practical applications associated with transportation in ice-covered seas and with the design of offshore structures intended to survive in the presence of ice. The present investigation has the objective to clarify ideas about floe sizes and to propose techniques for measuring them. Measurements are presented with the primary aim to illustrate points of technique or approach. A preliminary discussion of the floe size distribution of sea ice is devoted to questions of definition and of measurement.

  14. 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) ...

  15. Forecasting Bering Sea ice edge behavior

    SciTech Connect

    Pritchard, R.S. (Naval Postgraduate School, Monterey, CA (United States)); Mueller, A.C. (Flow Industries, Inc., Kent, WA (United States)); Yang, Y.S. (Arco Oil and Gas Co., Dallas, TX (United States)); 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.

  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. Sea ice feedback and Cenozoic evolution of Antarctic climate and ice Robert DeConto,1

    E-print Network

    Massachusetts at Amherst, University of

    Sea ice feedback and Cenozoic evolution of Antarctic climate and ice sheets Robert DeConto,1 David; published 24 August 2007. [1] The extent and thickness of Antarctic sea ice have important climatic effects explores the role of sea ice and related feedbacks in the Cenozoic evolution of Antarctic climate and ice

  18. Impact of ice temperature on microwave emissivity of thin newly formed sea ice

    Microsoft Academic Search

    Byong Jun Hwang; Jens K. Ehn; David G. Barber

    2008-01-01

    This study examines the impact of ice temperature on microwave emissivity over thin, newly formed sea ice at 6, 19, and 37 GHz during October 2003 in the southern Beaufort Sea, where the physical properties of newly formed sea ice were coincidently measured with microwave emissions. Six ice stations with distinct properties were selected and divided according to ice surface

  19. Airborne Measurement of Sea-Ice Thickness

    Microsoft Academic Search

    Joan Gardner; John Brozena

    2010-01-01

    The Naval Research Laboratory (NRL) is planning a major program of measurement and modeling of sea-ice thickness in the Arctic. The program will include in-situ, airborne and satellite measurements as well as development of coupled models of ocean, atmosphere and sea-ice. The authors' primary responsibility in this program will be the airborne measurement segment of the program utilizing the freeboard

  20. Coastal landfast sea ice decay and breakup in northern Alaska: Key processes and seasonal prediction

    NASA Astrophysics Data System (ADS)

    Petrich, Chris; Eicken, Hajo; Zhang, Jing; Krieger, Jeremy; Fukamachi, Yasushi; Ohshima, Kay I.

    2012-02-01

    Seasonal breakup of landfast sea ice consists of movement and irreversible ice detachment in response to winds or oceanic forces in the late stages of ice decay. The breakup process of landfast sea ice in the Chukchi Sea at Barrow, Alaska, was analyzed for the years 2000 through 2010 on the basis of local observations of snow and ice conditions, weather records, image sequences obtained from cameras, coastal X band marine radar, and satellite imagery. We investigated the relation of breakup to winds, tides, and nearshore current measurements from a moored acoustic Doppler current profiler. Two breakup modes are distinguished at Barrow on the basis of the degree of ice decay. Mechanical breakup due to wind and oceanic forces follows ablation and weakening of the ice. Thermal breakup is the result of ice disintegration under melt ponds, requiring little force to induce dispersion. Grounded pressure ridges are pivotal in determining the breakup mode. The timing of thermal breakup of the nearshore ice cover was found to correlate with the measured downwelling solar radiation in June and July. This linkage allows for the development of an operational forecast of landfast ice breakup. Results from forecasts during 2 years demonstrate that thermal breakup can be predicted to within a couple of days 2 weeks in advance. The cumulative shortwave energy absorbed by the ice cover provides for a measure of the state of ice decay and potential for disintegration. Discriminating between the two modes of breakup bears the potential to greatly increase forecasting skill.

  1. Wind-borne redistribution of snow across an Antarctic ice rise

    NASA Astrophysics Data System (ADS)

    King, J. C.; Anderson, P. S.; Vaughan, D. G.; Mann, G. W.; Mobbs, S. D.; Vosper, S. B.

    2004-06-01

    Redistribution of snow by the wind can drive spatial and temporal variations in snow accumulation that may affect the reconstruction of paleoclimate records from ice cores. In this paper we investigate how spatial variations in snow accumulation along a 13 km transect across Lyddan Ice Rise, Antarctica, are related to wind-borne snow redistribution. Lyddan Ice Rise is an approximately two-dimensional ridge which rises about 130 m above the surrounding ice shelves. Local slopes on its flanks never exceed 0.04. Despite this very smooth profile, there is a pronounced gradient in snow accumulation across the feature. Accumulation is highest on the ice shelf to the east (climatologically upwind) of the ice rise and decreases moving westward, with the lowest accumulation seen to the west (climatologically downwind) of the ice rise crest. Superimposed on this broad-scale gradient are large (20-30%), localized variations in accumulation on a scale of around 1 km that appear to be associated with local variations in surface slope of less than 0.01. The broad-scale accumulation gradient is consistent with estimates of wind-borne redistribution of snow made using wind speed observations from three automatic weather stations. The small-scale variability in accumulation is reproduced quite well using a snow transport model driven by surface winds obtained from an airflow model, providing that both the wind shear and static stability of the upwind flow are taken into account. We conclude that great care needs to be exercised in selecting ice core sites in order to avoid the possibility of blowing snow transport confounding climate reconstructions.

  2. Arctic sea ice decline: Faster than forecast

    Microsoft Academic Search

    Julienne Stroeve; Marika M. Holland; Walt Meier; Ted Scambos; Mark Serreze

    2007-01-01

    From 1953 to 2006, Arctic sea ice extent at the end of the melt season in September has declined sharply. All models participating in the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4) show declining Arctic ice cover over this period. However, depending on the time window for analysis, none or very few individual model simulations show trends

  3. Floating Ice-Algal Aggregates below Melting Arctic Sea Ice

    PubMed Central

    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

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

    SciTech Connect

    Bitz, C.M.; Battisti, D.S. [Univ. of Washington, Seattle, WA (United States)] [Univ. of Washington, Seattle, WA (United States); Moritz, R.E. [Univ. of Washington, Seattle, WA (United States)] [Univ. of Washington, Seattle, WA (United States); Beesley, J.A. [Univ. of Washington, Seattle, WA (United States)] [Univ. of Washington, Seattle, WA (United States)

    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.

  5. How does sea ice influence the isotopic composition of Arctic precipitation?

    NASA Astrophysics Data System (ADS)

    Faber, Anne-Katrine; Vinther, Bo; Sjolte, Jesper; Anker Pedersen, Rasmus

    2015-04-01

    Stable water isotope records from Greenland ice cores have been used extensively to reconstruct regional past climate variations. Measurements of vapor and snow samples on the Greenland ice sheet have shown that the isotopic composition of precipitation is an integrated signal of several regional climate variables rather than a unique proxy for local changes in temperature. In order to improve our knowledge of past climate changes an improved understanding of the regional climate variations on the isotope signal is essential. Here we investigate the influence of variations in sea ice cover on the isotopic composition of precipitation in present-day Arctic. We use the model isoCAM3, an isotope-equipped version of the National Center for Atmospheric Research Community Atmosphere Model version 3. Four simulations and one control simulation are performed with prescribed SSTs and sea ice using ERA-Interim data. Each of the four runs simulates the atmospheric and isotopic response to Arctic oceanic conditions for selected years within the satellite era (1979-2013). Results show that the isotopic composition of Arctic precipitation is sensitive to changes in sea ice extent, with reduced ice extent causing more enriched isotopes and vice versa. Results also show that different configurations of sea ice cover yield different distributions of the isotopic response. However, the effects of the sea ice anomalies on the modeled isotope ratios in precipitation over the Greenland ice sheet are negligible.

  6. 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.

  7. Statistical Analyses of High-Resolution Aircraft and Satellite Observations of Sea Ice: Applications for Improving Model Simulations

    NASA Astrophysics Data System (ADS)

    Farrell, S. L.; Kurtz, N. T.; Richter-Menge, J.; Harbeck, J. P.; Onana, V.

    2012-12-01

    Satellite-derived estimates of ice thickness and observations of ice extent over the last decade point to a downward trend in the basin-scale ice volume of the Arctic Ocean. This loss has broad-ranging impacts on the regional climate and ecosystems, as well as implications for regional infrastructure, marine navigation, national security, and resource exploration. New observational datasets at small spatial and temporal scales are now required to improve our understanding of physical processes occurring within the ice pack and advance parameterizations in the next generation of numerical sea-ice models. High-resolution airborne and satellite observations of the sea ice are now available at meter-scale resolution or better that provide new details on the properties and morphology of the ice pack across basin scales. For example the NASA IceBridge airborne campaign routinely surveys the sea ice of the Arctic and Southern Oceans with an advanced sensor suite including laser and radar altimeters and digital cameras that together provide high-resolution measurements of sea ice freeboard, thickness, snow depth and lead distribution. Here we present statistical analyses of the ice pack primarily derived from the following IceBridge instruments: the Digital Mapping System (DMS), a nadir-looking, high-resolution digital camera; the Airborne Topographic Mapper, a scanning lidar; and the University of Kansas snow radar, a novel instrument designed to estimate snow depth on sea ice. Together these instruments provide data from which a wide range of sea ice properties may be derived. We provide statistics on lead distribution and spacing, lead width and area, floe size and distance between floes, as well as ridge height, frequency and distribution. The goals of this study are to (i) identify unique statistics that can be used to describe the characteristics of specific ice regions, for example first-year/multi-year ice, diffuse ice edge/consolidated ice pack, and convergent/divergent ice zones, (ii) provide datasets that support enhanced parameterizations in numerical models as well as model initialization and validation, (iii) parameters of interest to Arctic stakeholders for marine navigation and ice engineering studies, and (iv) statistics that support algorithm development for the next-generation of airborne and satellite altimeters, including NASA's ICESat-2 mission. We describe the potential contribution our results can make towards the improvement of coupled ice-ocean numerical models, and discuss how data synthesis and integration with high-resolution models may improve our understanding of sea ice variability and our capabilities in predicting the future state of the ice pack.

  8. Real-Time Observations of Optical Properties of Arctic Sea Ice with an Autonomous System

    NASA Astrophysics Data System (ADS)

    Wang, C.; Gerland, S.; Nicolaus, M.; Granskog, M. A.; Hudson, S. R.; Perovich, D. K.; Karlsen, T. I.; Fossan, K.

    2012-12-01

    The recent drastic changes in the Arctic sea ice cover have altered the interaction of solar radiation and sea ice. To improve our understanding of this interaction, a Spectral Radiation Buoy (SRB) for measuring sea ice optical properties was developed, based on a system used during the last International Polar Year at the drift of "Tara" across the Arctic Ocean. A first version of the SRB was deployed on drifting ice in the high Arctic in April 2012. It includes three Satlantic spectral radiometers (two in air, one under ice), covering the wavelength range from 347 nm to 804 nm with 3.3 nm spectral resolution, a bio-shutter to protect the under-ice radiometer, a data logger to handle and store collected data, and an Iridium satellite modem to transfer data in real-time. The under-ice radiometer is mounted on an adjustable under-ice arm, and the other instruments are mounted on a triangular frame frozen into the ice. The SRB measures simultaneously, autonomously and continuously the spectral fluxes of incident and reflected solar radiation, as well as under-ice irradiance, water temperature and water pressure every hour. So far, between mid April and early August 2012, the system has drifted about 600 km, from the starting position near the North Pole towards the Fram Strait. The data collected during this deployment, so far, already demonstrate that this system is suitable for autonomous and long-term observations over and under sea ice in harsh conditions. Along with the SRB, commercially available Ice Mass Balance buoys (IMB) were deployed on the same ice floe. In the vicinity of the site, manned baseline measurements of snow and sea ice physical properties have been carried out during the SRB deployment. The combined datasets allow description of the evolution of the ice floe during seasonal melt. With snow melt, the spectral surface albedo decreased and the transmittance through the snow and ice increased after mid-April, especially when melt ponds started to develop in July.

  9. Assessment of EOS Aqua AMSR-E Arctic Sea Ice Concentrations using Landsat-7 and Airborne Microwave Imagery

    NASA Technical Reports Server (NTRS)

    Cavalieri, Donald J.; Markus, Thorsten; Hall, Dorothy K.; Gasiewski, Albin J.; Klein, Marian; Ivanoff, Alvaro

    2006-01-01

    An assessment of Advanced Microwave Scanning Radiometer Earth Observing System (AMSR-E) sea ice concentrations under winter conditions using ice concentrations derived from Landsat-7 Enhanced Thematic Mapper Plus (ETM+) imagery obtained during the March 2003 Arctic sea ice validation field campaign is presented. The National Oceanic and Atmospheric Administration Environmental Technology Laboratory's Airborne Polarimetric Scanning Radiometer Measurements, which were made from the National Aeronautics and Space Administration P 3B aircraft during the campaign, were used primarily as a diagnostic tool to understand the comparative results and to suggest improvements to the AMSR-E ice concentration algorithm. Based on the AMSR-E/ETM+ comparisons, a good overall agreement with little bias (approx. 1%) for areas of first year and young sea ice was found. Areas of new ice production result in a negative bias of about 5% in the AMSR-E ice concentration retrievals, with a root mean square error of 8%. Some areas of deep snow also resulted in an underestimate of the ice concentration (approx. 10%). For all ice types combined and for the full range of ice concentrations, the bias ranged from 0% to 3%, and the rms errors ranged from 1% to 7%, depending on the region. The new-ice and deep-snow biases are expected to be reduced through an adjustment of the new-ice and ice-type C algorithm tie points.

  10. 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.

  11. Processes driving sea ice variability in the Bering Sea in an eddying ocean/sea ice model: anomalies from the mean

    E-print Network

    Eisenman, Ian

    Processes driving sea ice variability in the Bering Sea in an eddying ocean/sea ice model 2014 # Springer-Verlag Berlin Heidelberg 2014 Abstract A fine-resolution (1/10°) ocean/sea ice model to determine the basin-scale and local balances controlling the variability of sea ice anomalies from the mean

  12. Decadal to seasonal variability of Arctic sea ice albedo

    E-print Network

    Agarwal, S; Wettlaufer, J S

    2011-01-01

    A controlling factor in the seasonal and climatological evolution of the sea ice cover is its albedo $\\alpha$. Here we analyze Arctic data from the Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder and assess the seasonality and variability of broadband albedo from a 23 year daily record. We produce a histogram of daily albedo over ice covered regions in which the principal albedo transitions are seen; high albedo in late winter and spring, the onset of snow melt and melt pond formation in the summer, and fall freeze up. The bimodal late summer distribution demonstrates the combination of the poleward progression of the onset of melt with the coexistence of perennial bare ice with melt ponds and open water, which then merge to a broad peak at $\\alpha \\gtrsim $ 0.5. We find the interannual variability to be dominated by the low end of the $\\alpha$ distribution, highlighting the controlling influence of the ice thickness distribution and large-scale ice edge dynamics. The statistics obtained pro...

  13. Sea Ice Yearly Minimum 1979-2007

    NSDL National Science Digital Library

    At the end of each summer, sea ice cover in the Arctic Ocean reaches its minimum extent and what is left is what is called the perennial ice cover (mainly thick multi-year ice floes). The area of perennial ice has been steadily decreasing since the satellite record began in 1979, at a rate of about 10 percent per decade. This visualization shows the annual minimum extent of sea ice in the Arctic Ocean from 1979 to 2007. A graph is overlaid that shows the area in millions of square kilometers for each year's minimum day. The previous record minimum (2005) and the new 2007 record minimum, far below the previous record and 38 percent lower than the climatological average, are highlighted. The visualization may be streamed from the website or downloaded in several formats.

  14. HCHO in Antarctic snow: Preservation in ice cores and air-snow exchange

    Microsoft Academic Search

    Manuel A. Hutterli; Roger C. Bales; Joseph R. McConnell; Richard W. Stewart

    2002-01-01

    Formaldehyde (HCHO) measurements in snow and shallow firn at three Antarctic sites gave concentrations around 6 ppbw in surface snow and 1 ppbw and lower below 1–2 m depth. The variable concentration patterns in shallow snow and firn result from temperature-dependent uptake and release of HCHO in response to annual temperature cycles. Deeper concentrations are constant with depth, and apparently

  15. 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.

  16. A model for the consolidation of rafted sea ice

    Microsoft Academic Search

    E. Bailey; D. L. Feltham; P. R. Sammonds

    2010-01-01

    Rafting is one of the important deformation mechanisms of sea ice. This process is widespread in the north Caspian Sea, where multiple rafting produces thick sea ice features, which are a hazard to offshore operations. Here we present a one-dimensional, thermal consolidation model for rafted sea ice. We consider the consolidation between the layers of both a two-layer and a

  17. Polarimetric Remote Sensing of Sea Ice in the Beaufort Sea

    Microsoft Academic Search

    S. V. Nghiem; R. Kwok; M. R. Drinkwater

    1992-01-01

    Polarimetric remote sensing data and physical interpretations are presented in this paper for sea ice in the Beaufort sea under cold winter conditions. The data were collected in March 1988 with the Jet Propulsion Laboratory (JPL) polarimetric airborne SAR. The full covariance matrices were obtained from the scattering data with proper consideration of the polarimetric calibration. Images were then processed

  18. 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.

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

    Microsoft Academic Search

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

    2010-01-01

    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

  20. Arctic sea ice freeboard from CryoSat-2: Validation using data from the first IceBridge underflight

    NASA Astrophysics Data System (ADS)

    Connor, L. N.; Laxon, S. W.; McAdoo, D. C.; Ridout, A.; Cullen, R.; Farrell, S.; Francis, R.

    2011-12-01

    Exact determination of thickness changes in Arctic sea ice is a primary goal of ESA's CryoSat-2 mission. Since its launch on April 8, 2010, CryoSat has collected data to map sea ice thickness and thereby monitor climate-driven ice thickness change. On April 20, 2010 just 12 days after CryoSat's launch - during NASA's IceBridge Spring 2010 campaign, the NASA DC-8 conducted a spatially and temporally coincident survey along some 670 km of a CryoSat ground-track in the northernmost Arctic Ocean. The DC-8 survey was flown out and back along the CryoSat ground-track. The DC-8 collected two laser altimetry datasets: (1) Laser Vegetation Imaging Sensor (LVIS) data, and (2) scanning laser Airborne Topographic Mapper (ATM) data. IceBridge also collected a number of other important data types including digital photography of sea ice, snow thickness radar, Ku-band radar altimetry and gravimetry, which are coincident and nearly simultaneous with SAR-mode Synthetic aperture Interferometric Radar ALtimeter (SIRAL) data collected by CryoSat. LVIS data were collected on the outbound high-altitude (25,000 feet) flight leg while ATM data were collected on the return, low-altitude (1500 feet) flight leg. CryoSat's SIRAL altimeter data are used to retrieve freeboard, i.e., the height of the ice surface above that of the local sea surface (observed in leads). Freeboard can be used to estimate sea ice thickness by assuming the ice is in isostatic equilibrium. In this investigation we compare freeboard retrievals from CryoSat with freeboard estimates derived using IceBridge data. Corrections for snow thickness are applied using IceBridge radar data. Freeboards retrieved using (a) LVIS data and (b) ATM data, are compared with CryoSat freeboard estimates. These two comparisons taken together provide an important assessment of CryoSat's capabilities to precisely map freeboard and thickness change of Arctic sea ice.

  1. MIZMAS Forecast of Sea Ice Thickness and Drift in the Beaufort Sea Marginal Ice Zone

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Schweiger, A. J. B.; Steele, M.; Stern, H. L., III

    2014-12-01

    A significant decline of Arctic sea ice has been observed in recent years. The decline was particularly steep during summers 2007-2013, when the arctic sea ice extent decreased to the lowest levels observed in the satellite era. The summer melt back was most severe in the Pacific sector including the Beaufort Sea where increasing areas of warming open water and marginal ice zone (MIZ) have been observed. To enhance our understanding of MIZ processes, an Office of Naval Research MIZ initiative is under way, which is an integrated program of observations and numerical simulations to investigate ice-ocean-atmosphere dynamics in and around the Beaufort Sea MIZ. In early 2014, the observation team of this program deployed 4 clusters of instruments of various platforms in the Beaufort Sea in order to capture the processes that affect MIZ evolution during the ice melt season. To assist the field work, we have developed a numerical framework for 48-hour forecast of sea ice thickness and drift in and around the Beaufort Sea MIZ using the Marginal Ice Zone ice/ocean Modeling and Assimilation System (MIZMAS). MIZMAS is a variant of the Pan-arctic Ice/Ocean Modeling and Assimilation System (PIOMAS), with a high-resolution focus of the Chukchi, Beaufort, and Bering seas. The 48-hour sea ice forecast system is forced by the forecast atmospheric data from the NCEP (National Center for Environmental Prediction) Climate Forecast System version 2 (CFSv2). The CFSv2 forecast ranges from hours to months and the forecast atmospheric data are widely accessible, thus ideal for forcing our sea ice forecast over a range of time scales. The sea ice forecast system has been used to predict sea ice thickness in the Beaufort Sea MIZ 48 hours in advance, focusing on the areas around the 4 clusters. It has also been used to predict the movement of these clusters. In this presentation, we will assess MIZMAS' forecast skills by comparing available ice thickness observations and the actual cluster trajectories. We will examine ways to improve the forecast system. We will also explore the possibility to extend the forecast to a seasonal time scale.

  2. 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.

  3. Albedo Drop on the Greenland Ice Sheet: Relative Impacts of Wet and Dry Snow Processes

    NASA Astrophysics Data System (ADS)

    Chen, J.; Polashenski, C.

    2014-12-01

    The energy balance of the Greenland Ice Sheet (GIS) is strongly impacted by changes in snow albedo. MODIS (Moderate Resolution Imaging Spectroradiometer) observations indicate that the GIS albedo has dropped since the early part of this century. We analyze data from the MODIS products MOD10A1 for broadband snow albedo and MOD09A1 for surface spectral reflectance since 2001 to better explain the physical mechanisms driving these changes. The MODIS products are filtered, and the data is masked using microwave-derived surface melt maps to isolate albedo changes due to dry snow processes from those driven by melt impacts. Results show that the majority of recent changes in the GIS albedo - even at high elevations - are driven by snow wetting rather than dry snow processes such as grain metamorphosis and aerosol impurity deposition. The spectral signature of the smaller changes occurring within dry snow areas suggests that grain metamorphosis dominates the albedo decline in these regions.

  4. 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.

  5. Influence of ice and snow covers on the UV exposure of terrestrial microbial communities: dosimetric studies.

    PubMed

    Cockell, Charles S; Rettberg, Petra; Horneck, Gerda; Wynn-Williams, David D; Scherer, Kerstin; Gugg-Helminger, Anton

    2002-08-01

    Bacillus subtilis spore biological dosimeters and electronic dosimeters were used to investigate the exposure of terrestrial microbial communities in micro-habitats covered by snow and ice in Antarctica. The melting of snow covers of between 5- and 15-cm thickness, depending on age and heterogeneity, could increase B. subtilis spore inactivation by up to an order of magnitude, a relative increase twice that caused by a 50% ozone depletion. Within the snow-pack at depths of less than approximately 3 cm snow algae could receive two to three times the DNA-weighted irradiance they would receive on bare ground. At the edge of the snow-pack, warming of low albedo soils resulted in the formation of overhangs that provided transient UV protection to thawed and growing microbial communities on the soils underneath. In shallow aquatic habitats, thin layers of heterogeneous ice of a few millimetres thickness were found to reduce DNA-weighted irradiances by up to 55% compared to full-sky values with equivalent DNA-weighted diffuse attenuation coefficients (K(DNA)) of >200 m(-1). A 2-mm snow-encrusted ice cover on a pond was equivalent to 10 cm of ice on a perennially ice covered lake. Ice covers also had the effect of stabilizing the UV exposure, which was often subject to rapid variations of up to 33% of the mean value caused by wind-rippling of the water surface. These data show that changing ice and snow covers cause relative changes in microbial UV exposure at least as great as those caused by changing ozone column abundance. PMID:12208033

  6. 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.

  7. 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.

  8. As the Ice Keeps Thinning Update on Arctic People-Sea Ice

    E-print Network

    Kuligowski, Bob

    As the Ice Keeps Thinning Update on Arctic People-Sea Ice Connections, 2007­2009 Igor Krupnik `people' projects supporting indigenous climate and sea ice observations: · Understanding environmental · Sea Ice Knowledge and Use (SIKU) # 166 · Exchange for Local Observations and Knowledge (ELOKA) # 187

  9. Propaganda, News, or Education: Reporting Changing Arctic Sea Ice Conditions

    NASA Astrophysics Data System (ADS)

    Leitzell, K.; Meier, W.

    2010-12-01

    The National Snow and Ice Data Center provides information on Arctic sea ice conditions via the Arctic Sea Ice News & Analysis (ASINA) website. As a result of this effort to explain climatic data to the general public, we have attracted a huge amount of attention from our readers. Sometimes, people write to thank us for the information and the explanation. But people also write to accuse us of bias, slant, or outright lies in our posts. The topic of climate change is a minefield full of political animosity, and even the most carefully written verbiage can appear incomplete or biased to some audiences. Our strategy has been to report the data and stick to the areas in which our scientists are experts. The ASINA team carefully edits our posts to make sure that all statements are based on the science and not on opinion. Often this means using some technical language that may be difficult for a layperson to understand. However, we provide concise definitions for technical terms where appropriate. The hope is that by communicating the data clearly, without an agenda, we can let the science speak for itself. Is this an effective strategy to communicate clearly about the changing climate? Or does it downplay the seriousness of climate change? By writing at a more advanced level and avoiding oversimplification, we require our readers to work harder. But we may also maintain the attention of skeptics, convincing them to read further and become more knowledgeable about the topic.

  10. Rapid formation of a sea ice barrier east of Svalbard

    Microsoft Academic Search

    S. V. Nghiem; M. L. Van Woert; G. Neumann

    2005-01-01

    Daily SeaWinds scatterometer images acquired by the QuikSCAT satellite show an elongated sea ice feature that formed very rapidly (~1-2 days) in November 2001 east of Svalbard over the Barents Sea. This sea ice structure, called ``the Svalbard sea ice barrier,'' spanning approximately 10° in longitude and 2° in latitude, restricts the sea route and poses a significant navigation hazard.

  11. Rapid formation of a sea ice barrier east of Svalbard

    Microsoft Academic Search

    S. V. Nghiem; M. L. Van Woert; G. Neumann

    2005-01-01

    Daily SeaWinds scatterometer images acquired by the QuikSCAT satellite show an elongated sea ice feature that formed very rapidly (?1–2 days) in November 2001 east of Svalbard over the Barents Sea. This sea ice structure, called “the Svalbard sea ice barrier,” spanning approximately 10° in longitude and 2° in latitude, restricts the sea route and poses a significant navigation hazard.

  12. On producing sea ice deformation data sets from SAR-derived sea ice motion

    NASA Astrophysics Data System (ADS)

    Bouillon, S.; Rampal, P.

    2015-04-01

    We propose a method to reduce the error generated when computing sea ice deformation fields from synthetic aperture radar (SAR)-derived sea ice motion. The method is based on two steps. The first step consists of using a triangulation of the positions taken from the sea ice trajectories to define a mesh on which a first estimate of sea ice deformation is computed. The second step consists of applying a specific smoother to the deformation field to reduce the artificial noise that arises along discontinuities in the sea ice motion field. This method is here applied to RADARSAT Geophysical Processor System (RGPS) sea ice trajectories having a temporal and spatial resolution of about 3 days and 10 km, respectively. From the comparison between unfiltered and filtered fields, we estimate that the artificial noise causes an overestimation of about 60% of opening and closing. The artificial noise also has a strong impact on the statistical distribution of the deformation and on the scaling exponents estimated with multifractal analysis. We also show that a similar noise is present in the deformation fields provided in the widely used four-point deformation RGPS data set. These findings may have serious implications for previous studies as the constant overestimation of the opening and closing could lead to a large overestimation of freezing in leads, salt rejection and sea ice ridging.

  13. Impact of Surface Roughness on AMSR-E Sea Ice Products

    NASA Technical Reports Server (NTRS)

    Stroeve, Julienne C.; Markus, Thorsten; Maslanik, James A.; Cavalieri, Donald J.; Gasiewski, Albin J.; Heinrichs, John F.; Holmgren, Jon; Perovich, Donald K.; Sturm, Matthew

    2006-01-01

    This paper examines the sensitivity of Advanced Microwave Scanning Radiometer (AMSR-E) brightness temperatures (Tbs) to surface roughness by a using radiative transfer model to simulate AMSR-E Tbs as a function of incidence angle at which the surface is viewed. The simulated Tbs are then used to examine the influence that surface roughness has on two operational sea ice algorithms, namely: 1) the National Aeronautics and Space Administration Team (NT) algorithm and 2) the enhanced NT algorithm, as well as the impact of roughness on the AMSR-E snow depth algorithm. Surface snow and ice data collected during the AMSR-Ice03 field campaign held in March 2003 near Barrow, AK, were used to force the radiative transfer model, and resultant modeled Tbs are compared with airborne passive microwave observations from the Polarimetric Scanning Radiometer. Results indicate that passive microwave Tbs are very sensitive even to small variations in incidence angle, which can cause either an over or underestimation of the true amount of sea ice in the pixel area viewed. For example, this paper showed that if the sea ice areas modeled in this paper mere assumed to be completely smooth, sea ice concentrations were underestimated by nearly 14% using the NT sea ice algorithm and by 7% using the enhanced NT algorithm. A comparison of polarization ratios (PRs) at 10.7,18.7, and 37 GHz indicates that each channel responds to different degrees of surface roughness and suggests that the PR at 10.7 GHz can be useful for identifying locations of heavily ridged or rubbled ice. Using the PR at 10.7 GHz to derive an "effective" viewing angle, which is used as a proxy for surface roughness, resulted in more accurate retrievals of sea ice concentration for both algorithms. The AMSR-E snow depth algorithm was found to be extremely sensitive to instrument calibration and sensor viewing angle, and it is concluded that more work is needed to investigate the sensitivity of the gradient ratio at 37 and 18.7 GHz to these factors to improve snow depth retrievals from spaceborne passive microwave sensors.

  14. Will Arctic sea ice thickness initialization improve seasonal forecast skill?

    NASA Astrophysics Data System (ADS)

    Day, J. J.; Hawkins, E.; Tietsche, S.

    2014-11-01

    Arctic sea ice thickness is thought to be an important predictor of Arctic sea ice extent. However, coupled seasonal forecast systems do not generally use sea ice thickness observations in their initialization and are therefore missing a potentially important source of additional skill. To investigate how large this source is, a set of ensemble potential predictability experiments with a global climate model, initialized with and without knowledge of the sea ice thickness initial state, have been run. These experiments show that accurate knowledge of the sea ice thickness field is crucially important for sea ice concentration and extent forecasts up to 8 months ahead, especially in summer. Perturbing sea ice thickness also has a significant impact on the forecast error in Arctic 2 m temperature a few months ahead. These results suggest that advancing capabilities to observe and assimilate sea ice thickness into coupled forecast systems could significantly increase skill.

  15. High-precision GPS autonomous platforms for sea ice dynamics and physical oceanography

    NASA Astrophysics Data System (ADS)

    Elosegui, P.; Wilkinson, J.; Olsson, M.; Rodwell, S.; James, A.; Hagan, B.; Hwang, B.; Forsberg, R.; Gerdes, R.; Johannessen, J.; Wadhams, P.; Nettles, M.; Padman, L.

    2012-12-01

    Project "Arctic Ocean sea ice and ocean circulation using satellite methods" (SATICE), is the first high-rate, high-precision, continuous GPS positioning experiment on sea ice in the Arctic Ocean. The SATICE systems collect continuous, dual-frequency carrier-phase GPS data while drifting on sea ice. Additional geophysical measurements also collected include ocean water pressure, ocean surface salinity, atmospheric pressure, snow-depth, air-ice-ocean temperature profiles, photographic imagery, and others, enabling sea ice drift, freeboard, weather, ice mass balance, and sea-level height determination. Relatively large volumes of data from each buoy are streamed over a satellite link to a central computer on the Internet in near real time, where they are processed to estimate the time-varying buoy positions. SATICE system obtains continuous GPS data at sub-minute intervals with a positioning precision of a few centimetres in all three dimensions. Although monitoring of sea ice motions goes back to the early days of satellite observations, these autonomous platforms bring out a level of spatio-temporal detail that has never been seen before, especially in the vertical axis. These high-resolution data allows us to address new polar science questions and challenge our present understanding of both sea ice dynamics and Arctic oceanography. We will describe the technology behind this new autonomous platform, which could also be adapted to other applications that require high resolution positioning information with sustained operations and observations in the polar marine environment, and present results pertaining to sea ice dynamics and physical oceanography.

  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. Impacts of Organic Macromolecules, Chlorophyll and Soot on Arctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Ogunro, O. O.; Wingenter, O. W.; Elliott, S.; Flanner, M.; Dubey, M. K.

    2014-12-01

    Recent intensification of Arctic amplification can be strongly connected to positive feedback relating black carbon deposition to sea ice surface albedo. In addition to soot deposition on the ice and snow pack, ice algal chlorophyll is likely to compete as an absorber and redistributor of energy. Hence, solar radiation absorption by chlorophyll and some components of organic macromolecules in/under the ice column is currently being examined to determine the level of influence on predicted rate of ice loss. High amounts of organic macromolecules and chlorophyll are produced in global sea ice by the bottom microbial community and also in vertically distributed layers where substantial biological activities take place. Brine channeling in columnar ice can allow for upward flow of nutrients which leads to greater primary production in the presence of moderate light. Modeling of the sea-ice processes in tandem with experiments and field observations promises rapid progress in enhancing Arctic ice predictions. We are designing and conducting global climate model experiments to determine the impact of organic macromolecules and chlorophyll on Arctic sea ice. Influences on brine network permeability and radiation/albedo will be considered in this exercise. Absorption by anthropogenic materials such as soot and black carbon will be compared with that of natural pigments. We will indicate areas of soot and biological absorption dominance in the sense of single scattering, then couple into a full radiation transfer scheme to attribute the various contributions to polar climate change amplification. The work prepares us to study more traditional issues such as chlorophyll warming of the pack periphery and chemical effects of the flow of organics from ice internal communities. The experiments started in the Arctic will broaden to include Antarctic sea ice and shelves. Results from the Arctic simulations will be presented.

  18. 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.

  19. Distinguishing ice from snow for melt modeling using daily observations from MODIS

    NASA Astrophysics Data System (ADS)

    Rittger, Karl; Bryant, Anne C.; Brodzik, Mary J.; Painter, Thomas H.; Armstrong, Richard

    2014-05-01

    In high mountainous regions of the Earth during melt periods, both seasonal snow and glacier ice melt may contribute to surface water and ground water feeding streams. In these regions there are often few in-situ observations that can help distinguish between the two components of melt, particularly across large mountain ranges. Understanding the contribution of melt water from the seasonal snow and glacier ice sources informs us about the current state of the water cycle and how a changing climate may alter the water cycle. In this study, we analyze daily time series of MODIS data products to distinguish ice from snow as the seasonal snowpack recedes, revealing melt over glacier ice surfaces. Broadband albedo increases as ice is exposed because of larger grain sizes and dust/debris on the glacier surface. To investigate the grain sizes we use estimates from the MODIS Snow Covered Area and Grain Size Model (MODSCAG) and MODIS Dust Radiative Forcing in Snow (MODDRFS) derived from MODIS surface reflectance (MOD09GA). MODSCAG uses the shape of the spectrum selected by a spectral mixture analysis model while MODDRFS uses the Normalized Difference Grain Size Index (NDGSI). Comparison of the grain sizes with grain sizes derived from the Airborne Visible/Infrared Imaging Spectrometer have demonstrated higher accuracy for the NDGSI approach. In addition to analysis of grain sizes, we use 2 standard albedo products from the MODIS, the Terra Daily Snow Cover algorithm (MOD10A1) that uses a narrow-to-broadband conversion scheme to create an integrated broadband albedo and Surface Reflectance BRDF/Albedo (MOD43) product that provides albedo in three broad bands. We focus on the Hunza River basin, in the Upper Indus located in Northern Pakistan. We use the annual minimum ice and snow from the MODICE Persistent Ice and Snow (MODICE) algorithm to identify glaciated regions for analysis. The methods (MODSCAG, MODDRFS, MOD10A1, MOD43) all show sensitivity to exposed glacier surfaces. Further work will use a time series of melt modeling in this region to determine the contributions from seasonal snow versus glacier ice melt.

  20. Formation of an aggregate scale in Arctic sea ice

    Microsoft Academic Search

    Mark A. Hopkins; Susan Frankenstein; Alan S. Thorndike

    2004-01-01

    The ice pack covering northern seas is a mixture of thick ridged and rafted ice, undeformed ice, and open water. Conventional Eulerian Arctic sea ice models use a plastic yield surface to characterize the constitutive behavior of the pack. An alternative is to adopt a discontinuous Lagrangian approach and explicitly model the formation of leads and pressure ridges. We use

  1. Arctic Ocean sea ice volume: What explains its recent depletion?

    Microsoft Academic Search

    D. A. Rothrock; J. Zhang

    2005-01-01

    Various observations and model results point to an arctic sea ice cover that was extraordinarily thin in the 1990s. This thin ice cover was caused by a strengthened cyclonic circulation of wind and ice and by unusual warmth of springtime air temperatures. Here modeled sea ice volume is decomposed into two components: first, a dynamic or wind-forced response to interannually

  2. Comparison of the sea-ice thickness distribution in the Lincoln Sea and adjacent Arctic Ocean in 2004 and 2005

    NASA Astrophysics Data System (ADS)

    Haas, C.; Hendricks, S.; Doble, M.

    Results of helicopter-borne electromagnetic measurements of total (ice plus snow) sea-ice thickness performed in May 2004 and 2005 in the Lincoln Sea and adjacent Arctic Ocean up to 86° N are presented. Thickness distributions south of 84° N are dominated by multi-year ice with modal thicknesses of 3.9 m in 2004 and 4.2 m in 2005 (mean thicknesses 4.67 and 5.18 m, respectively). Modal and mean snow thickness on multi-year ice amounted to 0.18 and 0.30 m in 2004, and 0.28 and 0.35 m in 2005. There are also considerable amounts of 0.9-2.2 m thick first-year ice (modal thickness), mostly representing ice formed in the recurring, refrozen Lincoln Polynya. Results are in good agreement with ground-based electromagnetic thickness measurements and with ice types demarcated in satellite synthetic aperture radar imagery. Four drifting buoys deployed in 2004 between 86° N and 84.5° N show a similar pattern of a mean southward drift of the ice pack of 83 ± 18 km between May 2004 and April 2005, towards the coast of Ellesmere Island and Nares Strait. The resulting area decrease of 26% between the buoys and the coast is larger than the observed thickness increase south of 84° N. This points to the importance of shear in a narrow band along the coast, and of ice export through Nares Strait in removing ice from the study region.

  3. POLAR SEA ICE MAPPING FOR SEAWINDS Hyrum S. Anderson

    E-print Network

    Long, David G.

    POLAR SEA ICE MAPPING FOR SEAWINDS by Hyrum S. Anderson A thesis submitted to the faculty, College of Engineering and Technology #12;viii #12;ABSTRACT POLAR SEA ICE MAPPING FOR SEAWINDS Hyrum S sea ice. Advances in microwave remote sensing technology have allowed a large-scale and detailed study

  4. POLAR SEA-ICE CLASSIFICATION USING ENHANCED RESOLUTION NSCAT DATA

    E-print Network

    Long, David G.

    POLAR SEA-ICE CLASSIFICATION USING ENHANCED RESOLUTION NSCAT DATA Q. P. Remund and D. G. Long is shown to have high correlation with the NSIDC SSM/I derived multiyear ice maps. INTRODUCTION Polar sea is scientifically useful information. Several methods have been employed in the past to classify polar sea ice. Some

  5. Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications

    E-print Network

    Lindsay, Ron

    175 Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications Geophysical Is the Trajectory of Arctic Sea Ice? Harry L. Stern and Ronald W. Lindsay Polar Science Center, Applied Physics space of the Arctic sea ice thickness distribution, in which each dimension or component is the time

  6. Dynamic, In Situ Measurement of Sea-Ice Characteristic Length

    E-print Network

    Fox, Colin

    1 Dynamic, In Situ Measurement of Sea-Ice Characteristic Length Colin Fox Mathematics Department, Auckland, New Zealand Abstract­ We present a method for measuring the char- acteristic length of sea ice a range of localized measurements. The method is used to detemine the characteristic length of the sea ice

  7. 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.

  8. Are dust storm activities in North China related to Arctic ice snow cover?

    NASA Astrophysics Data System (ADS)

    Zhang, Jiashen; Peng, Gongbing; Huang, Mei; Zhang, Shihuang

    2006-07-01

    The generation and development of dust storms are controlled by land surface conditions and atmospheric circulations. The latter, in turn, is influenced by the global ice-snow cover. In this study, we examine the relationship between the characteristics of dust storm activities in north China and the changes of global climate patterns. In particular, we are interested in whether Arctic ice-snow cover is related to the dust storm frequencies and intensities in north China. Our analysis, based on the monthly data for the period from 1954 to 1994, shows that this is indeed the case. This result suggests that the Arctic ice-snow cover can be used for the long-term prediction of dust storm activities in north China, and dust storm activities also serve as an indicator of global climate change.

  9. Sea ice simulations based on fields generated by the GLAS GCM. [Goddard Laboratory for Atmospheric Sciences General Circulation Model

    NASA Technical Reports Server (NTRS)

    Parkinson, C. L.; Herman, G. F.

    1980-01-01

    The GLAS General Circulation Model (GCM) was applied to the four-month simulation of the thermodynamic part of the Parkinson-Washington sea ice model using atmospheric boundary conditions. The sea ice thickness and distribution were predicted for the Jan. 1-Apr. 30 period using the GCM-fields of solar and infrared radiation, specific humidity and air temperature at the surface, and snow accumulation; the sensible heat and evaporative surface fluxes were consistent with the ground temperatures produced by the ice model and the air temperatures determined by the atmospheric concept. It was concluded that the Parkinson-Washington sea ice model results in acceptable ice concentrations and thicknesses when used with GLAS GCM for the Jan.-Apr. period suggesting the feasibility of fully coupled ice-atmosphere simulations with these two approaches.

  10. Predicting September sea ice: Ensemble skill of the SEARCH Sea Ice Outlook 2008-2013

    NASA Astrophysics Data System (ADS)

    Stroeve, Julienne; Hamilton, Lawrence C.; Bitz, Cecilia M.; Blanchard-Wrigglesworth, Edward

    2014-04-01

    Since 2008, the Study of Environmental Arctic Change Sea Ice Outlook has solicited predictions of September sea-ice extent from the Arctic research community. Individuals and teams employ a variety of modeling, statistical, and heuristic approaches to make these predictions. Viewed as monthly ensembles each with one or two dozen individual predictions, they display a bimodal pattern of success. In years when observed ice extent is near its trend, the median predictions tend to be accurate. In years when the observed extent is anomalous, the median and most individual predictions are less accurate. Statistical analysis suggests that year-to-year variability, rather than methods, dominate the variation in ensemble prediction success. Furthermore, ensemble predictions do not improve as the season evolves. We consider the role of initial ice, atmosphere and ocean conditions, and summer storms and weather in contributing to the challenge of sea-ice prediction.

  11. blowing snow as a source of ice crystals in supercooled orographic clouds

    NASA Astrophysics Data System (ADS)

    Geerts, Bart; Pokharel, Binod; Chu, Xia

    2015-04-01

    Winter storms are often accompanied by strong winds, especially over complex terrain. Under such conditions freshly fallen snow readily can be suspended. Most of that snow will be redistributed across the landscape (e.g. behind obstacles), but some may be lofted into the turbulent boundary layer, and even in the free atmosphere in areas of boundary layer separation near terrain crests, or in hydraulic jumps. These ice crystals, presumably mostly small, fractured particles, may enhance snow growth in clouds. This may explain why shallow orographic clouds, with cloud top temperatures too high for significant ice initiation, can produce (light) snowfall with remarkable persistence. Airborne radar and lidar data are presented to demonstrate the presence of blowing snow, boundary layer separation, and the glaciation of a shallow supercooled orographic cloud. Further evidence for the presence of blowing snow comes from a comparison between flight level (~700 m AGL) and ground-level snow size distributions. We will also present a parameterization for the aerial injection of ice crystals from the surface, as implemented in WRF.

  12. Tracking the Record Sea Ice Minimum in the Arctic Using National Ice Center Charts

    Microsoft Academic Search

    J. Woods; P. Clemente-Colón; J. Brinkley; S. Helfrich; W. Huang; B. Melchior; T. Arbetter

    2007-01-01

    The National\\/Naval Ice Center (NIC), in Suitland, MD, produces routine analyses of sea ice coverage in the Arctic. We create a Northern Hemispheric analyses based on bi-weekly charts for over 30 individual areas. Weekly charts of several key areas such as the High Arctic, Beaufort Sea, Chukchi Sea, North Sea, and Kara Sea are also produced. To create these charts,

  13. Implications of Arctic Sea Ice Reduction on Arctic Tropospheric Chemical Change (Invited)

    NASA Astrophysics Data System (ADS)

    Nghiem, S. V.

    2009-12-01

    We examine the drastic reduction of Arctic sea ice in this decade and discuss the potential implications on bromine, ozone, and mercury change in the Arctic troposphere. We are witnessing extraordinary change in the Arctic sea ice cover. In the context of a half century change, perennial sea ice, the class of thicker and older ice important to the stability of Arctic sea ice, has been declining precipitously in this decade. Perennial ice extent declines at rate of 0.5 million km2 per decade in the 1970s-1990s while there is no discernable trend in the 1950s-1960s. Abruptly, the rate of decrease has tripled to 1.5 million km2 per decade in the 2000s. A record was set in the reduction of Arctic perennial ice extent in winter 2008. By 1 March 2008, perennial ice extent was reduced by one million km2 compared to that at the same time in 2007, which continued the precipitous declining trend observed in this decade. While the record low of total ice extent in summer 2007 is a historical mark of sea ice loss, the distribution and extent of different sea ice classes in spring (March-May) are critical information to understand the implications of sea ice reduction on photochemical processes, such as bromine explosions, ozone depletion episodes (ODEs), gaseous elementary mercury depletion episodes (MDEs), which occur at the time of polar sunrise. In this regard, the drastic reduction of perennial ice means that the Arctic becomes dominated by seasonal ice consisting of thinner ice, more leads, polynyas, frost flowers, and salty snow (due to seawater spray from open water), representing the overall saltier condition of the Arctic sea ice cover conducive to ice-mediated chemical processes leading to Arctic tropospheric ODEs and MDEs. To date (2009), the extent of perennial sea ice remains low and the extent of the thinner and saltier seasonal ice continues to dominate the Arctic sea ice cover. The shift of the state of Arctic sea ice cover to the dominance domain of seasonal ice can impact photochemical processes, leading to potentially significant implications on Arctic chemical change. Such implications, within the context of Arctic climatic change, are to be investigated in order to assess consequential changes in the Arctic habitat that may affect the health of people and wildlife. Regarding Arctic climatic change, seemingly opposing scenarios of Arctic chemical change have been hypothesized. In the first scenario, if sea ice cover continues to reduce in a warming trend in the 21st century, frost flower growth and bromine explosions might be suppressed and thus there would be less ozone and mercury depletion. Alternatively, in a different scenario, if the extent of seasonal ice during spring time in the Arctic continues to expand together with more cold spells due to temperature extremes exacerbated by climatic change, the abundance of seasonal ice, leads, and frost flowers may lead to more prevalent episodic events of bromine explosion and more intensive tropospheric ozone and mercury depletion in cold episodes. However, fundamental science questions remain to be addressed, and we have formed an international science team to plan for a future interdisciplinary research on those issues.

  14. 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%.

  15. Recent wind driven high sea ice area export in the Fram Strait contributes to Arctic sea ice decline

    NASA Astrophysics Data System (ADS)

    Smedsrud, L. H.; Sirevaag, A.; Kloster, K.; Sorteberg, A.; Sandven, S.

    2011-10-01

    Arctic sea ice area has been decreasing for the past two decades. Apart from melting, the southward drift through Fram Strait is the main ice loss mechanism. We present high resolution sea ice drift data across 79° N from 2004 to 2010. Ice drift has been derived from radar satellite data and corresponds well with variability in local geostrophic wind. The underlying East Greenland current contributes with a constant southward speed close to 5 cm s-1, and drives around a third of the ice export. We use geostrophic winds derived from reanalysis data to calculate the Fram Strait ice area export back to 1957, finding that the sea ice area export recently is about 25% larger than during the 1960's. The increase in ice export occurred mostly during winter and is directly connected to higher southward ice drift velocities, due to stronger geostrophic winds. The increase in ice drift is large enough to counteract a decrease in ice concentration of the exported sea ice. Using storm tracking we link changes in geostrophic winds to more intense Nordic Sea low pressure systems. Annual sea ice area export likely has a significant influence on the summer sea ice variability and we find low values in the 1960's, the late 1980's and 1990's, and particularly high values during 2005-2008. The study highlights the possible role of variability in ice export as an explanatory factor for understanding the dramatic loss of Arctic sea ice during the last decades.

  16. Fracture prevalence during an unusual period of snow and ice in the Netherlands

    PubMed Central

    2014-01-01

    Background The objective of the current study was to assess the effect of an unusual 10-day snow and ice period on the prevalence of fractures in an emergency department (ED) in the Netherlands. Furthermore, patients with fractures during the snow and ice period were compared to those in the control period with respect to gender, age, location of accident, length of stay, disposition, and anatomical site of the injury. Methods Fracture prevalence during a 10-day study period with snow and ice (January 14, 2013 until January 23, 2013) was compared to a similar 10-day control period without snow or ice (January 16, 2012 until January 25, 2012). The records of all patients with a fracture were manually selected. Besides this, basic demographics, type of fracture, and location of the accident (inside or outside) were compared. Results A total of 1,785 patients visited the ED during the study period and 1,974 during the control period. A fracture was found in 224 patients during the study period and in 109 patients during the control period (P <0.01). More fractures sustained outside account for this difference. No differences were found in gender, mean age, and length of ED stay. However, during the snow and ice period the percentage of fractures in the middle-aged (31–60 yrs) was significantly higher than in the control period (P <0.01). Conclusions The number of fractures sustained more than doubled during a period with snow and ice as compared to the control period. In contrast to other studies outside the Netherlands, not the elderly, but the middle-aged were most affected by the slippery conditions. PMID:24872860

  17. 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.

  18. 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...

  19. 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...

  20. Mercury distribution, partitioning and speciation in coastal vs. inland High Arctic snow

    NASA Astrophysics Data System (ADS)

    Poulain, Alexandre J.; Garcia, Edenise; Amyot, Marc; Campbell, Peter G. C.; Ariya, Parisa A.

    2007-07-01

    Atmospheric mercury deposition on snow at springtime has been reported in polar regions, potentially posing a threat to coastal and inland ecosystems receiving meltwaters. However, the post-depositional fate of Hg in snow is not well known, and no data are available on Hg partitioning in polar snow. During snowmelt, we conducted a survey of Hg concentrations, partitioning and speciation in surface snow and at depth, over sea ice and over land along a 100 km transect across Cornwallis Island, NU, Canada. Total Hg concentrations [THg] in surface snow were low (less than 20 pmol L -1) and were significantly higher in marine vs. inland environments. Particulate Hg in surface snow represented up to 90% of total Hg over sea ice and up to 59% over land. At depth, [THg] at the snow/sea ice interface (up to 300 pmol L -1) were two orders of magnitude higher than at the snow/lake ice interface (ca. 2.5 pmol L -1). Integrated snow columns, sampled over sea-ice and over land, showed that particulate Hg was mostly bound to particles ranging from 0.45 to 2.7 ?m. Moreover, melting snowpacks over sea ice and over lake ice contribute to increase [THg] at the water/ice interfaces. This study indicates that, at the onset of snowmelt, most of the Hg in snow is in particulate form, particularly over sea ice. Low Hg levels in surface snow suggest that Hg deposited through early spring deposition events is partly lost to the atmosphere from the snowpack before snowmelt. The sea ice/snow interface may constitute a site for Hg accumulation, however. Further understanding of the cycling of mercury at the sea ice/snow and sea ice/seawater interfaces is thus warranted to fully understand how mercury enters the arctic food webs.

  1. Erosion and entrainment of snow and ice by pyroclastic density currents: some outstanding questions (Invited)

    NASA Astrophysics Data System (ADS)

    Walder, J. S.

    2010-12-01

    A pyroclastic density current moving over snow is likely to transform to a lahar if the pyroclasts incorporate enough (melting) snow and meltwater to bring the bulk water content of the mixture to about 35% by volume. However, the processes by which such a mixture forms are still not well understood. Walder (Bull. Volcanol., v. 62, 2000) showed experimentally the existence of an erosion mechanism that functions even in the absence of relative shear motion between pyroclasts and snow substrate: a portion of the snow melted by a blanket of pyroclasts is vaporized; the flux of water vapor upward through the pyroclasts may be enough to fluidize the pyroclasts, which then convect, rapidly scour the snow substrate and transform into a slurry. But these experiments do not tell us how moving pyroclasts would erode snow, and simply releasing a hot grain flow over a snow surface in the lab gives misleading results owing to improper scaling of ?/? , the ratio of the shear stress ? exerted by the pyroclastic flow to the shear strength ? of snow. There seems to be no way around this problem for experiments with actual snow. However, it may be possible to circumvent the scaling problem by replacing the snow substrate by a gas-fluidized particle bed: by varying the gas flux, the apparent shear strength of the particle bed can be varied. Such an investigation of erosional processes could be done at room temperature. Snow-avalanche studies (for example, Gauer and Issler, Ann. Glaciol. v. 38, 2003) may provide some insight into snow erosion by a pyroclastic density current. Snow is eroded at the base of a dense snow avalanche by abrasion, particle impacts, and—at the avalanche head—by plowing and a “blasting” mechanism associated with compression of the snowpack and expulsion of pore fluid (air). Erosion at the avalanche head seems to be particularly important. Similar processes are likely to occur when the over-riding flow comprises hot grains. The laboratory release of a hot grain flow over snow, although improperly scaled for investigating erosive processes, does demonstrate that snow hydrology and snowpack stability may be critical in the transformation of pyroclastic density currents to lahars. When such an experiment is run in a sloping flume, with meltwater able to drain freely at the base of the snow layer, the hot grain flow spreads over the snow surface and then comes to rest--no slurry is produced. In contrast, if meltwater drainage is blocked, the wet snow layer fails at its bed, mobilizes as a slush flow, and mixes with the hot grains to form a slurry. Ice layers within a natural snowpack would likewise block meltwater drainage and be conducive to the formation of slush flows. Abrasion and particle impacts—processes that have been studied intensively by engineers concerned with the wear of surfaces in machinery—probably play an important role in the erosion of glacier ice by pyroclastic density currents. A prime example may be the summit ice cap of Nevado del Ruiz, Colombia, which was left grooved by the eruption of 1985 (Thouret, J. Volcanol. Geotherm. Res., v. 41, 1990). Erosion of glacier ice is also strongly controlled by the orientation of crevasses, which can “capture” pyroclastic currents. This phenomenon was well displayed at Mount Redoubt, Alaska during the eruptions of 1989-90 and 2009.

  2. Development and properties of sea ice in the coastal regime of the southeastern Weddell Sea

    Microsoft Academic Search

    Hajo Eicken; Manfred A. Lange

    1989-01-01

    From October to December 1986 a program consisting of sea ice core analysis in combination with sea ice observations was carried out from the icebreaker R\\/V Polarstern as part of the Winter Weddel Sea Project. The ship operated in the central and southeastern Weddell Sea with interests focusing on the ice shelf front between 70°S and 77°S where a system

  3. 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.

  4. Sea ice dynamics as a control for halogen deposition in polar regions

    NASA Astrophysics Data System (ADS)

    Spolaor, Andrea; Plane, John M. C.; Vallelonga, Paul; Gabrieli, Jacopo; Cozzi, Giulio; Turetta, Clara; Kohler, Jack; Isaksson, Elisabeth; Barbante, Carlo

    2013-04-01

    Bromine and iodine chemistry is extremely active at the sea ice margins of both polar regions, with enhanced concentrations of BrO and IO in the air column compared to the open ocean surface or snow-covered land. So-called "Bromine explosions" occur principally over first-year sea ice close to the sea ice edge, and are the major source of reactive bromine in the polar atmosphere. This results in an increase of bromide (Br-) deposited to the snowpack, compared with the Br-Na sea water mass ratio. The main source of iodine is phytoplankton, which colonize the underside of sea ice, producing iodocarbons and probably I2. Though it has been discovered that atmospheric iodine around Antarctica is produced from algae growing on the underside of the relatively thin/seasonal sea ice, satellite measurements do not show exceptional iodine activity above Arctic sea ice. However, in opposition to Antarctica, boundary layer observations show relatively small atmospheric IO concentrations downwind of ice-free open ocean, including leads and polynias. Analysis of bromine and iodine has been carried out in the Talos Dome ice core (Antarctica) which covers the last 215 ky, and in a shallow/firn core drilled at the summit of the Holtedahlfonna glacier (Northern Spitsbergen, Svalbard), covering the last 10 years. Talos Dome Br- is positively correlated with temperature and negatively correlated with sodium (Na). Based on the Br-/Na seawater ratio, bromide is depleted in the ice during glacial periods and enriched during interglacial periods. Total iodine, consisting of iodide (I-) and iodate (IO3-), peaks during glacials with lower values during interglacial periods. Although iodate is believed to be the most stable iodine species in atmospheric aerosols, it was present only in the ice core only during glacial maxima. Glacial-interglacial changes in the multi-year sea ice extent will almost certainly alter the distance between the sea ice edge and Antarctic plateau, which will influence the total bromide flux (arising both from sea salt and Br- from bromine explosions) and its ratio with sodium. A simple 1-D transport model of this scenario is able to reproduce the measured fluxes of bromine and sodium. The seasonal sea ice extent will also alter the surface area available to algal colonization, and hence iodine emission. In support of the Antarctic results, analysis of iodine and bromine in the Svalbard shallow/firn core appears to confirm the linkage between sea ice and these halogens. In particular, changes in I concentration are associated with the extent of sea ice at spring time, while Br, evaluated as enrichment relative to the Br/Na sea water mass ratio, is influenced by changes in the seasonal sea ice area. The Arctic and Antarctic ice core results suggest that sea ice dynamics are arguably the primary driver of halogen fluxes in polar regions and that both halogens could be used to understand the past variability of sea ice.

  5. ConcepTest: Effect of Ice Sheet on Sea Level

    NSDL National Science Digital Library

    During the last ice age there was a large ice sheet over much of Canada and the northern U.S. What was the effect on global sea levels? a. Sea level was higher b. Sea level was lower c. Sea level was the same as ...

  6. How to Be Safe in Ice and Snow

    MedlinePLUS

    ... in the snow. Keeping your hands warm and dry is important because fingers are very sensitive to the cold. Drink Up! Sounds like advice for hot weather, not cold weather, right? Well, the truth is ...

  7. A decade of sea ice thickness mapping by airborne lidar between Greenland and the North Pole

    NASA Astrophysics Data System (ADS)

    Hvidegaard, S. M.; Forsberg, R.; Skourup, H.; Stenseng, L.; Hanson, S.

    2007-12-01

    Airborne laser altimetry provides a direct measurement of sea ice freeboard, when combined with a precise geoid model and a lowest-level filtering algorithm to take into account residual errors in GPS-positioning, ocean dynamic topography, tides etc. Using swath laser scanning, the method additionally gives detailed information on the geometry of leads, ridges and the distribution of thin ice and open water. The conversion of sea ice freeboard heights to thickness is based on the assumption of equilibrium, with major errors sources relating to snow depth and density of sea ice. In the paper we describe results of measurements with airborne laser north of Greenland, Ellesmere Island and in the Fram Strait region, carried out on a yearly basis since 1998, in the first years using a single beam laser, and since 2001 using swath laser scanning giving a resolution of approximately 1 m in the ice features. The campaigns have mostly been done in the spring period, typically in connection with airborne gravity surveys or CryoSat calibration and validation activities. Observed secular changes in the sea ice freeboard heights are masked by limited spatial and temporal extent of campaigns, as well as interannual variability in the sea ice regime of the region. To address the error sources in the lidar thickness determination, a number of in-situ and helicopter EM comparisons have been carried out, e.g latest in April 2007 around the Tara drifting station beyond the North Pole, as part of the Damocles project. In cooperation with ESA and APL, coincident Ku-band radar and laser systems have also been flown, giving a unique opportunity for airborne measurement of snow depth as well.

  8. 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.

  9. Recent wind driven high sea ice export in the Fram Strait contributes to Arctic sea ice decline

    NASA Astrophysics Data System (ADS)

    Smedsrud, L. H.; Sirevaag, A.; Kloster, K.; Sorteberg, A.; Sandven, S.

    2011-05-01

    Arctic sea ice area decrease has been visible for two decades, and continues at a steady rate. Apart from melting, the southward drift through Fram Strait is the main loss. We present high resolution sea ice drift across 79° N from 2004 to 2010. The ice drift is based on radar satellite data and correspond well with variability in local geostrophic wind. The underlying current contributes with a constant southward speed close to 5 cm s-1, and drives about 33 % of the ice export. We use geostrophic winds derived from reanalysis data to calculate the Fram Strait ice area export back to 1957, finding that the sea ice area export recently is about 25 % larger than during the 1960's. The increase in ice export occurred mostly during winter and is directly connected to higher southward ice drift velocities, due to stronger geostrophic winds. The increase in ice drift is large enough to counteract a decrease in ice concentration of the exported sea ice. Using storm tracking we link changes in geostrophic winds to more intense Nordic Sea low pressure systems. Annual sea ice export likely has a significant influence on the summer sea ice variability and we find low values in the 60's, the late 80's and 90's, and particularly high values during 2005-2008. The study highlight the possible role of variability in ice export as an explanatory factor for understanding the dramatic loss of Arctic sea ice the last decades.

  10. On the role of sea ice for Southern Ocean stratification

    NASA Astrophysics Data System (ADS)

    Haumann, F. Alexander; Münnich, Matthias; Gruber, Nicolas

    2013-04-01

    The formation, subsequent lateral transport, and melt of sea ice represents a key process for the determination of upper ocean stratification in the Southern Ocean. Sea ice is transported northward in large parts of the Southern Ocean by strong near-surface winds and melts along the ice edge south of the polar front, an important upwelling region. Here, it adds freshwater to the surface ocean, lowers the sea-water density, and possibly reduces upwelling by increasing the stratification. Consequently, this redistribution of freshwater in time and space affects the vertical overturning circulation which is an important determinant of the ocean-atmosphere CO2 exchange and, thus, of the global climate. We investigate the Southern Ocean sea-ice ocean system using satellite observations together with simulations with a newly developed regional ocean sea-ice model on the basis of ROMS. As it is not possible yet to derive sea-ice volume transport from remote sensing data due to a lack of ice thickness data, we quantify the freshwater flux exerted by the sea ice from the model and compare it to the observed sea-ice area transport. This shows that the transport is large in the Weddell and Ross Seas where sea ice extends to its lowest latitudes. We assess the importance of sea-ice freshwater transport on the stratification and circulation by comparing this flux to the net atmospheric freshwater flux from reanalysis data and by perturbing our model simulations.

  11. 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.

  12. Sea ice density estimation in the Bohai Sea using the hyperspectral remote sensing technology

    NASA Astrophysics Data System (ADS)

    Liu, Chengyu; Shao, Honglan; Xie, Feng; Wang, Jianyu

    2014-11-01

    Sea ice density is one of the significant physical properties of sea ice and the input parameters in the estimation of the engineering mechanical strength and aerodynamic drag coefficients; also it is an important indicator of the ice age. The sea ice in the Bohai Sea is a solid, liquid and gas-phase mixture composed of pure ice, brine pockets and bubbles, the density of which is mainly affected by the amount of brine pockets and bubbles. The more the contained brine pockets, the greater the sea ice density; the more the contained bubbles, the smaller the sea ice density. The reflectance spectrum in 350~2500 nm and density of sea ice of different thickness and ages were measured in the Liaodong Bay of the Bohai Sea during the glacial maximum in the winter of 2012-2013. According to the measured sea ice density and reflectance spectrum, the characteristic bands that can reflect the sea ice density variation were found, and the sea ice density spectrum index (SIDSI) of the sea ice in the Bohai Sea was constructed. The inversion model of sea ice density in the Bohai Sea which refers to the layer from surface to the depth of penetration by the light was proposed at last. The sea ice density in the Bohai Sea was estimated using the proposed model from Hyperion image which is a hyperspectral image. The results show that the error of the sea ice density inversion model is about 0.0004 g•cm-3. The sea ice density can be estimated through hyperspectral remote sensing images, which provide the data support to the related marine science research and application.

  13. Accumulation Variability and Wind-borne Snow Transport Across Lyddan Ice Rise, Antarctica

    NASA Astrophysics Data System (ADS)

    King, J. C.; Anderson, P. S.; Vaughan, D. G.; Mann, G. W.; Mobbs, S. D.; Vosper, S. B.

    2004-12-01

    Redistribution of snow by the wind is the major contributor to spatial variability in snow accumulation over Antarctica on scales from metres to a few kilometres. Even small variations in wind speed associated with very gentle topography can give rise to large accumulation variations as a result of the highly nonlinear relationship between wind speed and snow transport. In this talk we examine the relationships between wind, topography and snow accumulation using observations made across an Antarctic ice rise. Lyddan Ice Rise is an approximately two-dimensional ridge, about 15 km wide, that rises 130m above the surrounding ice shelves. Surveys carried out using conventional stake measurements and ground penetrating radar reveal surprisingly large accumulation variations across this relatively gentle feature. On the scale of the ice rise itself, there is a gradual decline in accumulation moving from the ice shelf on the climatologically-upwind side to the climatologically downwind slope, where accumulation is reduced to around 65% of its upwind value. Superimposed on this broad-scale gradient are large (20-30%), localized variations in accumulation on a scale of around 1 km that appear to be associated with local variations in surface slope of around 0.01. The observed variations in accumulation agree well with calculations of snow redistribution made using wind measurements from automatic weather stations and winds derived from an airflow model, lending support to the hypothesis that snow redistribution is the major control on accumulation at this location. We discuss how our observations may relate to studies of accumulation variability in other parts of Antarctica, particularly the "megadune" fields of East Antarctica.

  14. Ice and AIS: ship speed data and sea ice forecasts in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Löptien, U.; Axell, L.

    2014-12-01

    The Baltic Sea is a seasonally ice-covered marginal sea located in a densely populated area in northern Europe. Severe sea ice conditions have the potential to hinder the intense ship traffic considerably. Thus, sea ice fore- and nowcasts are regularly provided by the national weather services. Typically, the forecast comprises several ice properties that are distributed as prognostic variables, but their actual usefulness is difficult to measure, and the ship captains must determine their relative importance and relevance for optimal ship speed and safety ad hoc. The present study provides a more objective approach by comparing the ship speeds, obtained by the automatic identification system (AIS), with the respective forecasted ice conditions. We find that, despite an unavoidable random component, this information is useful to constrain and rate fore- and nowcasts. More precisely, 62-67% of ship speed variations can be explained by the forecasted ice properties when fitting a mixed-effect model. This statistical fit is based on a test region in the Bothnian Sea during the severe winter 2011 and employs 15 to 25 min averages of ship speed.

  15. 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.

  16. Polarimetric signatures of sea ice. 2: Experimental observations

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    Experimental observations of polarimetric signatures are presented for sea ice in the Beaufort Sea under cold winter conditions and interpreted with the composite model developed in Part 1. Polarimetric data were acquired in March 1988 with the Jet Propulsion Laboratory multifrequency airborne synthetic aperture radar (SAR) during the Beaufort Sea Flight Campaign. The experimental area was located near 75 N latitude and spanned 140 deg-145 deg W longitude. Selected sea ice scenes contain various ice types, including multiyear, thick first-year, and thin lead ice. Additionally, the C band SAR on the first European Remote Sensing Satellite provides supplementary backscattering data of winter Beaufort Sea ice for small incident angles (20 deg-26 deg) at vertical polarization. Sea ice characterization and environment data used in the model were collected at the Applied Physics Laboratory drifting ice station to the northeast of Prudhoe Bay; additional data from field and laboratory experiments are also utilized in this analysis. The model related sea ice polarimetric backscattering signatures to physical, structural, and electromagnetic properties of sea ice. Scattering mechanisms contributing to sea ice signatures are explained, and sensitivies of polarimetric signatures to sea ice characterization parameters are studied.

  17. Influence of stochastic sea ice parametrization on climate and the role of atmosphere–sea ice–ocean interaction

    PubMed Central

    Juricke, Stephan; Jung, Thomas

    2014-01-01

    The influence of a stochastic sea ice strength parametrization on the mean climate is investigated in a coupled atmosphere–sea ice–ocean model. The results are compared with an uncoupled simulation with a prescribed atmosphere. It is found that the stochastic sea ice parametrization causes an effective weakening of the sea ice. In the uncoupled model this leads to an Arctic sea ice volume increase of about 10–20% after an accumulation period of approximately 20–30 years. In the coupled model, no such increase is found. Rather, the stochastic perturbations lead to a spatial redistribution of the Arctic sea ice thickness field. A mechanism involving a slightly negative atmospheric feedback is proposed that can explain the different responses in the coupled and uncoupled system. Changes in integrated Antarctic sea ice quantities caused by the stochastic parametrization are generally small, as memory is lost during the melting season because of an almost complete loss of sea ice. However, stochastic sea ice perturbations affect regional sea ice characteristics in the Southern Hemisphere, both in the uncoupled and coupled model. Remote impacts of the stochastic sea ice parametrization on the mean climate of non-polar regions were found to be small. PMID:24842027

  18. Influence of stochastic sea ice parametrization on climate and the role of atmosphere-sea ice-ocean interaction.

    PubMed

    Juricke, Stephan; Jung, Thomas

    2014-06-28

    The influence of a stochastic sea ice strength parametrization on the mean climate is investigated in a coupled atmosphere-sea ice-ocean model. The results are compared with an uncoupled simulation with a prescribed atmosphere. It is found that the stochastic sea ice parametrization causes an effective weakening of the sea ice. In the uncoupled model this leads to an Arctic sea ice volume increase of about 10-20% after an accumulation period of approximately 20-30 years. In the coupled model, no such increase is found. Rather, the stochastic perturbations lead to a spatial redistribution of the Arctic sea ice thickness field. A mechanism involving a slightly negative atmospheric feedback is proposed that can explain the different responses in the coupled and uncoupled system. Changes in integrated Antarctic sea ice quantities caused by the stochastic parametrization are generally small, as memory is lost during the melting season because of an almost complete loss of sea ice. However, stochastic sea ice perturbations affect regional sea ice characteristics in the Southern Hemisphere, both in the uncoupled and coupled model. Remote impacts of the stochastic sea ice parametrization on the mean climate of non-polar regions were found to be small. PMID:24842027

  19. Space Radar Image of Weddell Sea Ice

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is the first calibrated, multi-frequency, multi-polarization spaceborne radar image of the seasonal sea-ice cover in the Weddell Sea, Antarctica. The multi-channel data provide scientists with details about the ice pack they cannot see any other way and indicates that the large expanse of sea-ice is, in fact, comprised of many smaller rounded ice floes, shown in blue-gray. These data are particularly useful in helping scientists estimate the thickness of the ice cover which is often extremely difficult to measure with other remote sensing systems. The extent, and especially thickness, of the polar ocean's sea-ice cover together have important implications for global climate by regulating the loss of heat from the ocean to the cold polar atmosphere. The image was acquired on October 3, 1994, by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour. This image is produced by overlaying three channels of radar data in the following colors: red (C-band, HH-polarization), green (L-band HV-polarization), and blue (L-band, HH-polarization). The image is oriented almost east-west with a center location of 58.2 degrees South and 21.6 degrees East. Image dimensions are 45 kilometers by 18 kilometers (28 miles by 11 miles). Most of the ice cover is composed of rounded, undeformed blue-gray floes, about 0.7 meters (2 feet) thick, which are surrounded by a jumble of red-tinged deformed ice pieces which are up to 2 meters (7 feet) thick. The winter cycle of ice growth and deformation often causes this ice cover to split apart, exposing open water or 'leads'. Ice growth within these openings is rapid due to the cold, brisk Antarctic atmosphere. Different stages of new-ice growth can be seen within the linear leads, resulting from continuous opening and closing. The blue lines within the leads are open water areas in new fractures which are roughened by wind. The bright red lines are an intermediate stage of new-ice growth perhaps 5 to 10 centimeters (2 to 4 inches) thick. The more extensive dark zones are covered by a slightly thicker layer of smooth, level ice up to 70 centimeters (28 inches) thick. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.v.(DLR), the major partner in science, operations, and data processing of X-SAR.

  20. An investigation into the effects of ice and snow accumulation on drumskin radome antennas and methods of their removal

    Microsoft Academic Search

    P. M. Young; R. L. Stuckey

    1987-01-01

    The first phase of this investigation was the development of an electrical model of a drumskin radome antenna coated with a layer of ice or snow. The characteristic effects of different ice\\/snow distributions were derived from this. The second phase was the construction of model anti\\/de-icing systems which were then tested in a climatic laboratory. This led to the development

  1. Recent Snow Accumulation Variability in Northwest Greenland from a Compilation of Snow Pits, Ice Cores, and Instrumental Records

    NASA Astrophysics Data System (ADS)

    Wong, G. J.; Osterberg, E. C.; Hawley, R. L.; Courville, Z.; Ferris, D. G.; Howley, J. A.; Caughey, S. K.; Lutz, E.; Overly, T. B.

    2014-12-01

    Accumulation (precipitation minus evaporation or sublimation) is fundamental to understanding the mass balance of the Greenland Ice Sheet (GIS). Increases in accumulation rates over an ice sheet may be driven by the higher saturation vapor pressure with rising temperatures (e.g., Davis et al., 2005), and/or changes in atmospheric circulation patterns such as the North Atlantic Oscillation (NAO) (Appenzeller et al., 1998; Mosley-Thompson et al., 2005). Ground-penetrating radar data taken along the 2011 Greenland Inland Traverse indicate that northwest Greenland accumulation rates have increased approximately ~10% in the dry-snow zone over the past 50 years (Hawley et al., 2014), with differences in accumulation values more pronounced in the lower-elevation, coastal region near Thule. A similar pattern is also observed in snow pit data collected along the traverse when compared to traverse snowpit data from the 1950s. Accumulation rates derived from northwest Greenland shallow cores, however, indicate no statistically significant trend in annual accumulation (Bales et al., 2001; Buchardt et al., 2012). Here we present a compilation of precipitation (accumulation) instrumental and proxy records from the northwest GIS in an effort to reconcile these observations and improve our understanding of NW Greenland accumulation variability over the past ~100 years. Our analysis incorporates records from snowpits, shallow cores, and historical datasets including precipitation data from coastal meteorological stations (Cappelen et al., 2011). We assess the sensitivity of snow accumulation to factors including topography, temperature variability, and changes in atmospheric circulation. Preliminary analyses support the hypothesis that accumulation has been rising in coastal regions of the ice sheet for the past two decades without a significant trend further inland.

  2. Energy Balance Modeling of Interannual Snow and Ice Storage in High Altitude Region by Dynamic Equilibrium Concept

    NASA Astrophysics Data System (ADS)

    Johnson, R. J.; Ohara, N.

    2014-12-01

    Snow models in the field of hydrologic engineering have barely incorporated the long-term effect of the inter-annual snow storage such as glaciers because the time scale of glacier dynamics is much longer than those of river flow and seasonal snowmelt. This study proposes an appropriate treatment for inland glaciers as systems in dynamic equilibrium that stay constant under a static climate condition. It is supposed that the snow/ice vertical movement from high elevation areas to valleys (lower elevation areas) by means of wind re-distribution, avalanches, and glaciation, may be considered as an equilibrator of the glacier system because it stimulates snow/ice ablation. The implicit physically-based modeling of such a dynamic equilibrium snow system is introduced and discussed for the long-term snow simulation at a regional scale. The developed model has been coupled with the Weather Research and Forecasting (WRF) model to compute the snow surface energy balance.

  3. Profiling atmospheric graupel, snow and ice using TRMM's PR and TMI

    Microsoft Academic Search

    J. P. Meagher; Z. S. Haddad

    2001-01-01

    Of TRMM's three instantaneous algorithms, the radar-only and combined radar-radiometer algorithms currently produce profiles of liquid rain only. These two algorithms do not attempt to estimate the graupel, snow or other ice distributions. This severely limits their usefulness in estimating the underlying latent heating due to the precipitation. While the radiometer algorithm does produce estimates of liquid rain and undifferentiated

  4. Temporal changes of microbial assemblages in the ice and snow cover of a high mountain lake

    Microsoft Academic Search

    Marisol Felip; Lluis Camarero; Jordi Catalan

    1999-01-01

    It has recently been shown that a rich community of microorganisms inhabits the slush layers of the winter cover of high mountain lakes. In this study, temporal changes in species assemblages and environmental conditions in the ice and snow cover of Lake Redoin the Pyrenees (Spain) are presented. The winter cover was a highly dynamic environment, in which major changes

  5. OBSERVATIONS OF SNOW AND ICE CRYSTALS WITH LOW TEMPERATURE SCANNING ELECTRON MICROSCOPY (REVIEW)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This review summarizes the advantages of LTSEM for observations of samples of snow and ice by illustrating the type of surface information that is obtainable, the resolution that can be attained and how the depth of field allows one to observe crystals with significant topography. In addition, we i...

  6. 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.

  7. CO2 Snow Depth and Subsurface Water-Ice Abundance in the

    E-print Network

    Zuber, Maria

    CO2 Snow Depth and Subsurface Water-Ice Abundance in the Northern Hemisphere of Mars I. G. Mars undergoes seasons in which volatile spe- cies, carbon dioxide (CO2) and, to a much lesser extent hemispheres consists of con- densed CO2 whose accumulation and sublima- tion are controlled mainly by solar

  8. 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.

    2015-02-01

    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 recommendation 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 in the snow services, but also the lake/river ice products and the glacier products were desired.

  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, 1867, Ke Au Okoa: "Na poohina o Hawaii--He wa poohina ole mai nei hoi keia o ua mau elemakule nei, o ke Loa, ua ilihune i kahi papale kapu keokeo ole." The grey-heads of Hawai`i Island--This is a time when

  10. Depicting northern wetland feedbacks in the climate system as affected by permafrost, snow and ice

    NASA Astrophysics Data System (ADS)

    Christensen, T. R.; Defrost Pi Team

    2011-12-01

    Many recent changes in northern ecosystems have been dramatic and have unexpectedly exceeded even aggressive projections. Some of these are expected to impact climate. However, the feedbacks from changing ecosystem functioning are complex, vary over space and time and are generally poorly understood. This presentation will focus on and put the northern wetland methane emission dynamics into the perspective of the other related climate feedbacks at play at high northern latitudes i.e. the carbon balance of terrestrial ecosystems at large, the energy exchange of the landscapes and impacts on this from changing snow and ice conditions as well as the off-shore issues with e.g. elevated methane concentrations in the bottom waters of the Laptev Sea. The presentation will show the first results and findings of a joint Nordic effort under the Nordic Top-Level Research Initiative (DEFROST) to define pivotal feedbacks and develop a shared framework within which novel analyses and model development can give new insights into the complex yet uncertain feedbacks. The process of integrated terrestrial, marine and atmospheric research combined with joint modeling efforts within DEFROST will be outlined as it develops toward improving process models and their incorporation into larger scale climate-ecosystem models that will be linked ultimately to Earth System Modeling initiatives. This presentation will provide an overview of progress towards this goal.

  11. 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

  12. IWICOS: Integrated Weather, Sea Ice and Ocean Service System

    Microsoft Academic Search

    Stein Sandven; Robin Berglund; Jyrki Haajanen; Ari Seinä; Morten Lind; Leif Toudal Petersen; Roberto Saldo; Halla Bjorg Baldursdottir; G. Hafsteinsson

    2003-01-01

    The objective of IWICOS is to develop a prototype marine information system that will provide end-users with a single-entry access point to meteorological, sea ice and oceanographic data and products in electronic form for users of operational services. These include national ice and weather services, shipping companies and sea traffic adminis- tration, icebreaker captains and ice pilots of ships, oil

  13. Lessons learned from the 2007 Arctic sea ice loss

    Microsoft Academic Search

    J. E. Kay; J. Stroeve; T. L'Ecuyer; C. O'Dell; M. Serreze

    2008-01-01

    Arctic sea ice is melting at unprecedented rates. Our work evaluates the atmospheric forcing on recent Arctic sea ice loss using satellite, ground-based, and reanalysis datasets. Here, we will focus on the 2007 melt season and the perspective gained after one year of additional observations and research. Recent studies have shown that the 2007 ice loss was driven both by

  14. Polarimetric remote sensing of sea ice - from theory to practice

    Microsoft Academic Search

    N. M. Nedeltchev; J. C. Peuch; H. Baudrand

    2002-01-01

    The employment of radars in remote sensing monitoring of polar regions is well known and largely proven practice today. In general the sea ice controls the heat transfer and mass-balance between the ocean-and the atmosphere. To interpret ice polarimetric signatures a composite microwave model is studied. The model relates the electromagnetic scattering from sea ice to its geophysical properties.

  15. Sea-ice and Circulation of Baffin Bay

    Microsoft Academic Search

    C. C. Tang

    2004-01-01

    The sea-ice, oceanographic and meteorological conditions in Baffin Bay are studied using historical hydrographic, satellite and meteorological data, and a set of current meter data from a mooring program of the Bedford Institute of Oceanography. Baffin Bay is partially covered by sea-ice all year except August and September. The interannual variation of the ice extent is shown to be correlated

  16. Time-dependence of sea-ice concentration and multiyear ice fraction in the Arctic Basin

    NASA Technical Reports Server (NTRS)

    Gloersen, P.; Zwally, H. J.; Chang, A. T. C.; Hall, D. K.; Campbell, W. J.; Ramseier, R. O.

    1978-01-01

    Microwave images of sea ice obtained by Nimbus-5 and the NASA CV-990 airborne laboratory are used to determine the time variation of the sea-ice concentration and multiyear ice fraction within the pack ice in the Arctic Basin. The images, constructed from data acquired from the electrically scanned microwave radiometer, are analyzed for four seasons during 1973-1975. Observations indicate significant variations in the sea-ice concentration in the spring, late fall, and early winter. Sea-ice concentrations as low as 50% were detected in large areas in the interior of the Arctic polar sea-ice pack. The applicability of passive-microwave remote sensing for monitoring the time dependence of sea-ice concentration is considered.

  17. 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

  18. 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.

  19. Ice and AIS: ship speed data and sea ice forecasts in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Löptien, U.; Axell, L.

    2014-07-01

    The Baltic Sea is a seasonally ice covered marginal sea located in a densely populated area in northern Europe. Severe sea ice conditions have the potential to hinder the intense ship traffic considerably. Thus, sea ice fore- and nowcasts are regularly provided by the national weather services. Typically, several ice properties are allocated, but their actual usefulness is difficult to measure and the ship captains must determine their relative importance and relevance for optimal ship speed and safety ad hoc. The present study provides a more objective approach by comparing the ship speeds, obtained by the Automatic Identification System (AIS), with the respective forecasted ice conditions. We find that, despite an unavoidable random component, this information is useful to constrain and rate fore- and nowcasts. More precisely, 62-67% of ship speed variations can be explained by the forecasted ice properties when fitting a mixed effect model. This statistical fit is based on a test region in the Bothnian Bay during the severe winter 2011 and employes 15 to 25 min averages of ship speed.

  20. Physical, dielectric, and C band microwave scattering properties of first-year sea ice during advanced melt

    Microsoft Academic Search

    Randall K. Scharien; Torsten Geldsetzer; David G. Barber; John J. Yackel; A. Langlois

    2010-01-01

    This paper investigates the influence of solar heating and intermittent cloud cover on the physical and dielectric properties of naturally snow-free, warm (>?2°), first-year sea ice (FYI) in the southeastern margin of the Beaufort Sea during advanced melt. A simple three-layer physical model describing the surface is introduced and copolarized C band microwave signatures are simulated using a multilayer scattering

  1. A New Parameterisation of Frazil and Grease Ice Formation in a Climate Sea Ice Model

    NASA Astrophysics Data System (ADS)

    Feltham, D. L.; Heorton, H. D.; Wilchinsky, A. V.

    2014-12-01

    An idealised model describing frazil ice formation in the ocean mixed layer beneath a lead in the sea ice cover is developed and incorporated into the sea ice climate model CICE. The frazil ice model assumes a steady state formation of single size frazil ice crystals. The crystals are uniformly distributed under the lead over the mixed layer depth and the lead width. The basic processes affecting the frazil ice mass balance is the rate of frazil ice formation due to the heat loss from the open water to the atmosphere, advection of heat and frazil ice volume into the lead from the water under sea ice, and precipitation of frazil ice crystals to the ocean surface and formation of grease ice. The grease ice is pushed against one of the lead edges by wind and water drag keeping the lead open. The frazil ice model is incorporated into CICE and used to simulate the sea ice state in the Arctic Basin and Southern Ocean.In contrast to the original frazil ice treatment in CICE which produces sea ice with only around 10% frazil ice fraction, the new model produces of order of 50% of frazil-derived sea ice, which corresponds better to observations. While the original model can be re-tuned in order to produce a similar average fraction of frazil ice by having a frazil collection thickness of 30 cm in the Antarctic and 5 cm in the Arctic, the new model's collection thickness is dynamically calculated, allowing for a larger collection thickness in large leads whereas the old model assumes it to be equal for wide and narrow leads. The new model keeps leads open for a longer period thus increasing the period of frazil ice formation. This is particularly important in the central Arctic where the new model's increased frazil ice production results in sea ice 0.5 m thicker than in the old model.

  2. 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), Italy {Institute of Arctic and Alpine Research and Department of Geography, University of Colorado at Boulder, UCB 450, Boulder, Colorado 80309, U.S.A. {Corresponding author: margherita

  3. Feature Identification Exercises: Clouds, Snow, and Ice Using MODIS

    NSDL National Science Digital Library

    2014-09-14

    This module consists of four exercises where users identify surface features, distinguish clouds from snow on the ground, and determine cloud phase using multispectral analysis. The module also includes an overview of multispectral techniques available on many operational and research polar-orbiting satellites. A page with links to real-time polar-orbiting data and information is also included.

  4. Arctic Sea Ice and Its Changes during the Satellite Period

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    Sea ice is a very important indicator and an effective modulator of regional and global climate change. Changes in sea ice will significantly affect the complex exchanges of momentum, heat, and mass between sea and the atmosphere, along with profound socio-economic influences due to its role in transportation, fisheries, hunting, polar animal habitat. Over the last two decades of the 20th century, the Arctic underwent significant changes in sea ice as part of the accelerated global warming of that period. More accurate, consistent, and detailed ice thickness, extent, and volume data are critical for a wide range of applications including climate change detection, climate modeling, and operational applications such as shipping and hazard mitigation. Satellite data provide an unprecedented opportunity to estimate and monitor Arctic sea ice routinely with relatively high spatial and temporal resolutions. In this study, a One-dimensional Thermodynamic Ice Model (OTIM) has been developed to estimate sea ice thickness based on the surface energy balance at a thermo-equilibrium state, containing all components of the surface energy balance. The OTIM has been extensively validated against submarine Upward-Looking Sonar (ULS) measurements, meteorological station measurements, and comprehensive numerical model simulations. Overall, OTIM-estimated sea ice thickness is accurate to within about 20% error when compared to submarine ULS ice thickness measurements and Canadian meteorological station measurements for ice less than 3 m. Along with sea ice extent information from the SSM/I, the Arctic sea ice volume can be estimated for the satellite period from 1984 to 2004. The OTIM has been used with satellite data from the extended Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder (APP-x) products for the Arctic sea ice thickness, and sequentially sea ice volume estimations, and following statistical analysis of spatial and temporal distribution and trends in sea ice extent, thickness, and volume over the satellite period has been performed. The preliminary results show clear evidence that the Arctic sea ice has been experiencing significant changes over the past two decades of the 20th century. The Arctic sea ice has been shrinking unexpected fast since 1997, the declines in sea ice extent, thickness, and volume are apparent in fall season. The accelerated changes in the Arctic sea ice since the 20thcentury should be paid extensive attention for the global warming study

  5. 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.

  6. Mapping Arctic sea ice from the Earth Resources Technology Satellite

    NASA Technical Reports Server (NTRS)

    Barnes, J. C. (principal investigator); Bowley, C. J.

    1973-01-01

    The author has identified the following significant results. Methods of detecting ice and for distinguishing between ice and clouds are discussed, and examples of ERTS-1 data showing ice distributions in northern Hudson Bay, M'Clure Strait, the eastern Beaufort Sea, and the Greenland Sea are presented. The results of the initial analysis of ERTS-1 data indicate that the locations of ice edges and ice concentrations can be accurately mapped, and that considerable information on ice type can be derived through use of the various spectral bands. Ice features as small as 80 to 100 m width can be mapped.

  7. 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.

  8. Study of Impacts of Arctic Sea Ice Reduction on Atmospheric Chemical Processes - The BROMEX 2012 Field Campaign

    NASA Astrophysics Data System (ADS)

    Nghiem, S. V.

    2012-12-01

    Arctic perennial sea ice has decreased drastically in the last decade and still remained low in spring 2012 as observed from scatterometer datasets acquired by QuikSCAT and Oceansat-2 satellites. In particular, the thinner, weaker, and saltier seasonal sea ice has dominated over the perennial ice in the Chukchi Sea and Beaufort Sea. To investigate impacts of sea ice reduction on atmospheric chemical processes, we conducted the BRomine, Ozone, and Mercury EXperiment in (BROMEX) in March-April 2012 around Barrow, extending out to a large region offshore and inland. Here we present overview results from BROMEX, which was successfully carried out by about 30 scientists, researchers, and field workers from multiple international institutions. For BROMEX, we coordinated and collected satellite data, including a number of near-real-time products, from multiple satellite instruments including MODIS, AMSR-E, GOME-2, SCIAMACHY, OMI, RADARSAT-2, Envisat ASAR, TanDEM-X, SMOS, CryoSat-2, and Oceansat-2. Over the BROMEX field region, we made measurements and collected sea ice, snow, ocean, and air samples for physical, meteorological, chemical, biological, and acoustic studies. A helicopter was used to deploy chemical and meteorological buoys in the Chukchi Sea and the Beaufort Sea. Measurements were also made with airborne sensors across sea ice, leads, lagoon, and tundra along various flight patterns of the ALAR aircraft. Furthermore, we coordinated with the NASA IceBridge P3 aircraft to collect surface temperature, surface height, snow depth, and ice thickness measurements. We set up and maintained field sites on sea ice and in the tundra to measure bromine, ozone, mercury, and other chemical species. Moreover, we obtained temperature data from many different types of temperature sensors for temperature accuracy assessment to identify potential issues that might cause errors or biases in temperature measurements. An enormous amount of in-situ snow and ice data was collected along extensive transects across the sea and landscape. BROMEX samples, measurements, and datasets are being analyzed, and results will be shown in a number of other presentations by members of the BROMEX interdisciplinary science team.

  9. Snow- and ice-height change in Antarctica from satellite gravimetry and altimetry data

    NASA Astrophysics Data System (ADS)

    Mémin, A.; Flament, T.; Rémy, F.; Llubes, M.

    2014-10-01

    We combine the surface-elevation and surface-mass change derived from Envisat data and GRACE solutions, respectively, to estimate regional changes in air and ice content of the surface of the Antarctic Ice Sheet (AIS) between January 2003 and October 2010. This leads, upon certain assumptions, to the separation of the rates of recent snow-accumulation change and that of ice-mass change. We obtain that the height of ice in Thwaites and Pine Island glaciers sectors decreases (?-15.7 cm/yr) while that in the Kamb glacier sector increases (?5.3 cm/yr). The central part of the East AIS is mostly stable while the whole Dronning Maud Land coast is dominated by an increase in snow accumulation. The Kemp land regions show an ice-mass gain that accounts for 67-74% of the observed rates of elevation change in these regions. A good agreement is obtained over 68% of the investigated area, mostly in the East AIS, between our estimated rates of snow accumulation change and the predicted rates of the monthly surface mass balance derived from a regional atmospheric climate model.

  10. Antarctic Sea Ice Extent Variability and Its Global Connectivity

    Microsoft Academic Search

    Xiaojun Yuan; Douglas G. Martinson

    2000-01-01

    This study statistically evaluates the relationship between Antarctic sea ice extent and global climate variability. Temporal cross correlations between detrended Antarctic sea ice edge (SIE) anomaly and various climate indices are calculated. For the sea surface temperature (SST) in the eastern equatorial Pacific and tropical Indian Ocean, as well as the tropical Pacific precipitation, a coherent propagating pattern is clearly

  11. Modelling the sea ice in the Nares Strait

    Microsoft Academic Search

    Till A. S. Rasmussen; Nicolai Kliem; Eigil Kaas

    2010-01-01

    A three dimensional coupled ocean (HYCOM) and sea ice model (CICE) is applied to a regional setup of the Lincoln Sea, the Nares Strait, and the Baffin Bay. As the sea ice model is originally developed for global simulations, boundary conditions have been implemented for the regional setup. The model results are compared with satellite images and with the large

  12. 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.

  13. Tracking sea ice floes from the Lincoln Sea to Nares Strait and deriving large scale melt from coincident spring and summer (2009) aerial EM thickness surveys

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Satellite observations demonstrate a decreasing summer Arctic sea ice extent over the past ~40 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. 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 the derivation of large scale (individual floe) seasonal sea ice mass balance in the Lincoln Sea and Nares Strait. Large scale melt estimates are derived by comparing aerial borne electromagnetic induction thickness surveys conducted in spring with surveys conducted in summer 2009. The comparison of coincident floes is ensured by tracking sea ice using ENIVSAT ASAR and MODIS satellite imagery. Only EM thickness survey sections of floes that were surveyed in both spring and summer are analyzed and the resulting modal thicknesses of the distributions, which represent the most abundant ice type, are compared to determine the difference in thickness and therefore total melt (snow+basal ice+surface ice melt). Preliminary analyses demonstrate a bulk (regional ice tracking) seasonal total thickness variability of 1.1m, Lincoln Sea modal thickness 3.7m (April, 2009) and Nares Strait modal thickness 2.6m (August 2009)(Fig1). More detailed floe tracking, in depth analysis of EM surveys and removal of deformed ridged/rafted sea ice (due to inaccuracies over deformed ice) will result in more accurate melt estimates for this region and will be presented. The physical structure of deformed sea ice and the footprint of the EM instrument typically underestimate the total thicknesses observed. Seasonal variations of sea ice properties can add additional uncertainty to the response of the EM instrument over deformed ridged/rafted sea ice. Here we will present additional analysis of the data comparing total thickness to ridge height that will provide some insight into the magnitude of seasonal discrepancies experienced by the EM instrument over deformed ice.

  14. 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

  15. NAO influence on net sea ice production and exchanges in the Arctic region: a numerical study

    E-print Network

    Hu, Aixue

    NAO influence on net sea ice production and exchanges in the Arctic region: a numerical study Aixue The variability of net sea ice production and sea ice exchange between the Arctic and its adjacent seas are studied, using a coupled sea ice-ocean general circulation model. The wind driven divergence (or ice flux

  16. Estimation of sea-ice parameters using a local particle filter

    E-print Network

    van Leeuwen, Peter Jan

    Estimation of sea-ice parameters using a local particle filter Arjen Terwisscha van Scheltinga1@ualberta.ca #12;Abstract The modeling of sea-ice (thermo-)dynamics and sea-ice-ocean interaction has proven to be difficult due to the highly nonlinear viscous-elastic properties of the sea-ice. In sea-ice-ocean models

  17. 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...

  18. Large sea ice outflow into the Nares Strait in 2007

    Microsoft Academic Search

    R. Kwok; L. Toudal Pedersen; P. Gudmandsen; S. S. Pang

    2010-01-01

    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

  19. [Characteristics of carbonaceous aerosol concentration in snow and ice of glaciers in Tianshan Mountains].

    PubMed

    Wang, Sheng-Jie; Zhang, Ming-Jun; Wang, Fei-Teng; Li, Zhong-Qin

    2012-03-01

    The snow and ice samples, collected at Glacier No. 1 at the headwaters of Urumqi River (UG1) and Glacier No. 51 at Haxilegen of Kuytun River (HG51) in 2002 and 2004, were analyzed for organic carbon (OC) and element carbon (EC) by thermal/ optical reflectance (TOR). The spatio-temporal characteristics and environmental significance of OC and EC concentration were discussed in details. The concentration order of total carbon (TC) was: snowpack of west branch on UG1 (1 943 ng x g(-1)) > snowpack of east branch on UG1 (989 ng x g(-1)) > snowpack of HG51 (150 ng x g(-1)) > glacier ice of east branch on UG1 (77 ng x g(-1)), and the concentration order of OC and EC lay similar as TC. The concentration of OC and EC in snowpack of Tianshan Mountains were 557 ng x g(-1) and 188 ng x g(-1), respectively. Concentration peak of carbonaceous aerosol usually appeared near the dust layer at the bottom section of snowpack, but the some sudden events could increase the concentration in the surface snow. Because of the seasonality of carbon emission (e. g. heating and agricultural activities) and transportation (e. g. atmospheric circulation), the concentration of carbonaceous aerosol increased from July to November with fluctuations. Difference on the order of magnitude might exist between the concentration in snow (firn) and glacier ice, which was influenced by the glacier surroundings, sampling situation and other factors. EC on the surface snow affected the albedo significantly, and an average albedo reduction of 0.22 in the wavelength of 300-700 nm was simulated by SNICAR (snow, ice, and aerosol radiative) model. PMID:22624355

  20. Determination of Sea Ice Parameters With the NIMBUS 7 SMMR

    Microsoft Academic Search

    D. J. Cavalieri; P. Gloersen; W. J. Campbell

    1984-01-01

    A method of determining sea ice parameters using dual-polarized multispectral radiance data obtained with the NIMBUS 7 Scanning Multichannel Microwave Radiometer (SMMR) is presented. Sea ice concentration is determined both at a 60-km resolution from the polarization at the 1.7-cm wavelength and at a 30-km resolution using the polarization at the 0.81-cm wavelength. Multiyear sea ice fraction is obtained from

  1. Remote Sensing of Sea Ice in the Northern Sea Route: Studies and Applications

    Microsoft Academic Search

    Roger G. Barry

    2008-01-01

    Given the rapid changes that are under way in Arctic sea ice extent, Remote Sensing of Sea Ice in the Northern Sea Route is a timely work. The Northern Sea Route (NSR), along the Arctic coast of Russia, has a long history, dating back to 1932, when the Soviet Union established the NSR administration to develop hydrometeorological services. Shipping along

  2. 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.

  3. Tertiary ice sheet dynamics: The snow gun hypothesis

    Microsoft Academic Search

    M. L. Prentice; R. K. Matthews

    1991-01-01

    We observe strong negative correlation between Tertiary low- to mid-latitude planktonic foarminiferal delta18O and the difference between the data and coeval benthic foraminiferal delta18. Late Quaternary data do not show this correlation. Coupling statisical model\\/delta18O comparisons and evidence for Antarctic ice and ocean temperature variation, we infer that Tertiary ice volume, recorded by tropical planktonic delta18O, increased as the deep

  4. Airborne Grid Sea-Ice Surveys for Comparison with CryoSat-2

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    The U.S. Naval Research Laboratory is engaged in a study of the changing Arctic with a particular focus on ice thickness and distribution variability. The purpose is to optimize computer models used to predict sea ice changes. An important part of our study is to calibrate/validate CryoSat-2 ice thickness data prior to its incorporation into new ice forecast models. The large footprint of the CryoSat-2 altimeter over sea-ice is a significant issue in any attempt to ground-truth the data. Along-track footprints are reduced to ~ 300 m by SAR processing of the returns. However, the cross-track footprint is determined by the topography of the surface. Further, the actual return is the sum of the returns from individual reflectors within the footprint making it difficult to interpret the return, and optimize the waveform tracker. We therefore collected a series of grids of airborne scanning lidar and nadir pointing radar on sub-satellite tracks over sea-ice that would extend far enough cross-track to capture the illuminated area. One difficulty in the collection of grids comprised of adjacent overlapping tracks is that the ice moves as much as 300 m over the duration of a single track (~ 10 min). With a typical lidar swath width of 500m we needed to adjust the survey tracks in near real-time for the ice motion. This was accomplished by a photogrammetric method of ice velocity determination (RTIME) reported in another presentation. Post-processing refinements resulted in typical track-to-track miss-ties of ~ 1-2 m, much of which could be attributed to ice deformation over the period of the survey. An important factor is that we were able to reconstruct the ice configuration at the time of the satellite overflight, resulting in an accurate representation of the surface illuminated by CryoSat-2. Our intention is to develop a model of the ice surface using the lidar grid which includes both snow and ice using radar profiles to determine snow thickness. In 2013 a set of 6 usable grids 5-20 km wide (cross-track) by 10-30 km long were collected north of Barrow, AK. In 2014 a further 5 narrower grids (~5km) were collected. 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.

  5. Modeling ocean wave propagation under sea ice covers

    NASA Astrophysics Data System (ADS)

    Zhao, Xin; Shen, Hayley H.; Cheng, Sukun

    2015-02-01

    Operational ocean wave models need to work globally, yet current ocean wave models can only treat ice-covered regions crudely. The purpose of this paper is to provide a brief overview of ice effects on wave propagation and different research methodology used in studying these effects. Based on its proximity to land or sea, sea ice can be classified as: landfast ice zone, shear zone, and the marginal ice zone. All ice covers attenuate wave energy. Only long swells can penetrate deep into an ice cover. Being closest to open water, wave propagation in the marginal ice zone is the most complex to model. The physical appearance of sea ice in the marginal ice zone varies. Grease ice, pancake ice, brash ice, floe aggregates, and continuous ice sheet may be found in this zone at different times and locations. These types of ice are formed under different thermal-mechanical forcing. There are three classic models that describe wave propagation through an idealized ice cover: mass loading, thin elastic plate, and viscous layer models. From physical arguments we may conjecture that mass loading model is suitable for disjoint aggregates of ice floes much smaller than the wavelength, thin elastic plate model is suitable for a continuous ice sheet, and the viscous layer model is suitable for grease ice. For different sea ice types we may need different wave ice interaction models. A recently proposed viscoelastic model is able to synthesize all three classic models into one. Under suitable limiting conditions it converges to the three previous models. The complete theoretical framework for evaluating wave propagation through various ice covers need to be implemented in the operational ocean wave models. In this review, we introduce the sea ice types, previous wave ice interaction models, wave attenuation mechanisms, the methods to calculate wave reflection and transmission between different ice covers, and the effect of ice floe breaking on shaping the sea ice morphology. Laboratory experiments, field measurements and numerical simulations supporting the fundamental research in wave-ice interaction models are discussed. We conclude with some outlook of future research needs in this field.

  6. 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.

  7. Modifying the current sea ice thickness initialization in CFSv2 to improve prediction of Arctic surface sea ice

    NASA Astrophysics Data System (ADS)

    Collow, Thomas; Wang, Wanqiu; Kumar, Arun

    2015-04-01

    Sea ice thickness has been known to influence patterns of surface sea ice concentration for several months into the future. Here, two sea ice thickness datasets were investigated, namely from the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR) and the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) developed at the Polar Science Center. Monthly data from 1982-2013 were used. The focus was on the predictability of the September sea ice minimum. Both CFSR and PIOMAS assimilate observed sea ice concentration which is then used to produce sea ice thickness values. It was found that PIOMAS had a greater downward trend in total sea ice volume in the last ten years. Comparisons to Ice, Cloud, and Land Elevation Satellite (ICESat) data revealed better agreement from the PIOMAS sea ice thickness data than from the CFSR data. To assess the impact of interannual anomalies of sea ice thickness, correlations between detrended anomalies of sea ice thickness from CFSR and PIOMAS and September sea ice concentration from NASA Team were calculated. For detrending, the best fit second order polynomial was removed from the raw data for both thickness and concentration. Findings showed that the area of significant increase in correlation when using the PIOMAS ice thickness dataset was greater than the area where there was a significant correlation decrease relative to using CFSR ice thickness. While the pattern was most prevalent out to a 3 month lead, it was still seen to some degree out to a 6 month lead. Using this information hindcasts were carried out using Version 2 of the Climate Forecast System (CFSv2) model forced with PIOMAS ice thickness rather than CFSR and initialized in the month of March for the years 2009-2014. Results show an improvement in the prediction of September sea ice coverage using the PIOMAS data. However, the new hindcasts were not perfect, particularly in the prediction of sea ice concentration which was overestimated when PIOMAS data were used. Despite these imperfections, the fact that the hindcasts have some improvement in skill out to a six month lead show promise for creating a better prediction of Arctic sea ice cover using the PIOMAS dataset.

  8. 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.

  9. Active laser system for sea ice control

    NASA Astrophysics Data System (ADS)

    Evtikhiev, Nickolay N.; Gaponov, Alexandr E.; Kuluba, Yury N.; Matous, Vladislav I.; Radominov, Oleg E.; Tuzikov, Vladimir Z.; Vargaftic, Vasiliy N.

    1997-01-01

    The airborne systems are used for complex investigations of coastline very successfully, for example it can be used to measure the depth of the sea, to discover the reefs and so on. Such information may be used in navigation too. The specific conditions of navigation in the North and Pole seas defines the necessity of exact knowledge about the ice cracks in order to find the possible direction of the ship movement. The active optical system, working in the near IR region, has many advantages before the passive one, especially if it is necessary to work during the polar night and at bad weather conditions. In this article we discuss the demands to the laser active airborne systems, that given the accurate picture of the ice with high resolution in the daytime and nighttime conditions. Such system based on the laser, mechanical scanner and avalanche photodiode is very compact, reliable and informative. The picture of the ice surface can be shown on the TV monitor, can be written to the memory and can be delivered to the processing center by the radiochannel. The experimental results are shown together with results of this system probing in the conditions of the North Pole Ocean.

  10. 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.

  11. Arctic ice island and sea ice movements and mechanical properties. Second quarterly report, 1 January31 March 1984

    Microsoft Academic Search

    W. M. Sackinger; W. J. Stringer; H. Serson

    1984-01-01

    Research activities for the second quarter are presented for the following tasks: (1) ice island; (2) Chukchi Sea pack ice age; and (3) mechanical properties of sea spray ice bonds structures. The research program on ice islands has four objectives: (1) establish a time history of all of the Arctic ice shelves and an historically-verified source function for ice islands

  12. Holocene sea ice in the main Arctic gateway

    NASA Astrophysics Data System (ADS)

    Müller, J.; Werner, K.; Stein, R.

    2012-04-01

    The Fram Strait, located between Greenland and Spitsbergen, plays a vital role in the subpolar North Atlantic climate system. This narrow deep-water passage does not only provide the major outlet for polar water and sea ice towards the North Atlantic, it also permits warm Atlantic water to enter the Arctic Ocean. The sea ice distribution in Fram Strait is thus intrinsically tied to the sea ice discharge in western Fram Strait and the advection of warm Atlantic water along the continental margin of Spitsbergen in eastern Fram Strait. Consequently, variations in the sea ice coverage relate to changes in this water mass exchange and may point to shifts in the oceanic and/or atmospheric circulation system. Organic geochemical and IRD data obtained from sediment cores from Fram Strait reveal that the sea surface conditions were prone to distinct environmental changes during the Holocene. By means of the biomarker IP25, a molecule associated with sea ice diatoms (Belt et al., 2007), and phytoplankton-derived biomarkers (indicative for open-water conditions) we reconstruct a long-term increase in (spring) sea ice occurrences from the Mid to the Late Holocene. Furthermore, we identify short-term sea ice fluctuations in eastern Fram Strait that are likely associated with recurring periods of a strengthened North Atlantic water inflow during the Late Holocene. These fluctuations also coincide with periods of changing glacier extents on Spitsbergen (Svendsen & Mangerud, 1997). At the inner continental shelf of East Greenland, the sea ice conditions, however, remained rather stable throughout the Holocene and a significant increase in sea ice discharge (IP25 accumulation) occurred only during the past 1,000 years. We find that the combination of IP25 with phytoplankton-derived biomarkers proves a valuable approach that helps to bypass ambiguous interpretations of the sea ice proxy record. In addition, this combinatory approach (PIP25; phytoplankton-IP25 index) may enable quantitative sea ice reconstructions (Müller et al., 2011).

  13. Sea-ice-thickness variability in the Chukchi Sea, spring and summer 2002–2004

    Microsoft Academic Search

    Kunio Shirasawa; Hajo Eicken; Kazutaka Tateyama; Toru Takatsuka; Toshiyuki Kawamura

    2009-01-01

    Measurements of sea-ice thickness were obtained from drill holes, an ice-based electromagnetic induction instrument (IEM), and a ship-borne electromagnetic induction instrument (SEM) during the early-melt season in the southern Chukchi Sea in 2002 and 2004, and in late summer 2003 at the time of minimum ice extent in the northern Chukchi Sea. An ice roughness criterion was applied to distinguish

  14. Home Atmosphere Sea Ice Ocean Land Greenland Biology Greenland Ice Sheet Mass Balance

    E-print Network

    Box, Jason E.

    Home Atmosphere Sea Ice Ocean Land Greenland Biology Greenland Ice Sheet Mass Balance E. Hanna 1 ice loss over Greenland. Recent warm events are about the same magnitude, if not smaller, than those warming, remain incompletely understood. Satellite Observations The Greenland ice sheet (GrIS) contains 7

  15. Seasonal comparisons of sea ice concentration estimates derived from SSM/I, OKEAN and RADARSAT data

    USGS Publications Warehouse

    Belchansky, G.I.; Douglas, D.C.

    2002-01-01

    The SSM/I microwave satellite radiometer and its predecessor SMMR are primary sources of information for global sea-ice and climate studies. However, comparisons of SSM/I, LANDSAT, AVHRR and ERS-1 SAR have shown substantial seasonal and regional differences in their estimates of sea ice concentration. To evaluate these differences, we compared SSM/I estimates of sea ice coverage derived with the NASA Team and Bootstrap algorithms to estimates made using RADARSAT, and OKEAN-01 satellite sensor data. The study area included the Barents, Kara Sea, Laptev Sea, and adjacent parts of the Arctic Ocean, during October 1995 through October 1999. Ice concentration estimates from spatially and temporally near-coincident imagery were calculated using independent algorithms for each sensor type. The OKEAN algorithm implemented the satellite's two-channel active (radar) and passive microwave data in a linear mixture model based on the measured values of brightness temperature and radar backscatter. The RADARSAT algorithm utilized a segmentation approach of the measured radar backscatter, and the SSM/I ice concentrations were derived at National Snow and Ice Data Center (NSIDC) using the NASA Team and Bootstrap algorithms. Seasonal and monthly differences between SSM/I, OKEAN, and RADARSAT ice concentrations were calculated and compared. Overall, total sea ice concentration estimates derived independently from near-coincident RADARSAT, OKEAN-01 and SSM/I satellite imagery demonstrated mean differences of less than 5.5 % (SD < 9.5%) during the winter period. Differences between the SSM/I NASA Team and the SSM/I Bootstrap concentrations were no more than 3.1 % (SD < 5.4%) during this period. RADARSAT and OKEAN-01 data both yielded higher total ice concentrations than the NASA Team and the Bootstrap algorithms. The Bootstrap algorithm yielded higher total ice concentrations than the NASA Team algorithm. Total ice concentrations derived from OKEAN-01 and SSM/I satellite imagery were highly correlated during winter, spring, and fall, with mean differences of less than 8.1% (SD < 15%) for the NASA Team algorithm, and less than 2.8 % (SD < 13.8%) for the Bootstrap algorithm. Respective differences between SSM/I NASA Team and SSM/I Bootstrap total concentrations were less than 5.3% (SD < 6.9%). Monthly mean differences between SSM/I and OKEAN differed annually by less than 6%, with smaller differences primarily in winter. The NASA Team and Bootstrap algorithms underestimated the total sea ice concentrations relative to the RADARSAT ScanSAR no more than 3.0% (SD<9 %) and 1.2% (SD < 7.5%) during cold months, and no more than 12% and 7% during summer, respectively. ScanSAR tended to estimate higher ice concentrations for ice concentrations greater than 50%, when compared to SSM/I during all months. ScanSAR underestimated total sea ice concentration by 2 % compared to the OKEAN-01 algorithm during cold months, and gave an overestimation by 2% during spring and summer months. Total NASA Team and Bootstrap sea ice concentration estimates derived from coincident SSM/I and OKEAN-01 data demonstrated mean differences no more than 5.3 % (SD < 7%), 3.1 % (SD < 5.5%), 2.0% (SD < 5.5%), and 7.3 % (SD < 10%) for fall, winter, spring, and summer periods, respectively. Large disagreements were observed between the OKEAN and NASA Team results in spring and summer for estimates of the first-year and multiyear age classes. The OKEAN-01 algorithm and data tended to estimate, on average, lower concentrations of young or first-year ice and higher concentrations of total and multiyear ice for all months and seasons. Our results contribute to the growing body of documentation about the levels of disparity obtained when seasonal sea ice concentrations are estimated using various types of satellite data and algorithms.

  16. Characteristics of modern atmospheric dust deposition in snow on the Penny Ice Cap, Baffin Island, Arctic Canada

    Microsoft Academic Search

    C. M. Zdanowicz; G. A. Zielinski; C. P. Wake

    1998-01-01

    We evaluated the concentration, size and distribution of insoluble dust microparticles in snow-pits on the Penny Ice Cap (PIC), Baffin Island, to define (1) the characteristics of modern atmospheric dust deposition at the site (2) the relative contributions of proximal and distal dust sources, and (3) the effects of summer melting on depositional signals in snow. The mean concentration (143

  17. 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.

  18. Sea Ice Data: A ReviewSea Ice Data: A Review Jim Maslanik, University of ColoradoJim Maslanik, University of Colorado

    E-print Network

    Sea Ice Data: A ReviewSea Ice Data: A Review Jim Maslanik, University of ColoradoJim Maslanik and skill level.Changes in personnel and skill level. #12;Satellite-Derived Sea Ice Data SetsSatellite-Derived Sea Ice Data Sets · Meteorological satellite products (visible/thermalMeteorological satellite

  19. Sea iceSea ice Data Sets Available within theData Sets Available within the WMO GDSIDB Project and FutureWMO GDSIDB Project and Future

    E-print Network

    Sea iceSea ice Data Sets Available within theData Sets Available within the WMO GDSIDB Project and Antarctic Research Institute &Arctic and Antarctic Research Institute & JCOMM Expert Team on Sea IceJCOMM Expert Team on Sea Ice #12;? ?Near North pole (82Near North pole (82ººNN,172,172ººW),W), 08 September

  20. Experimental Insights on Natural Lava-Ice/Snow Interactions and Their Implications for Glaciovolcanic and Submarine Eruptions

    NASA Astrophysics Data System (ADS)

    Edwards, B. R.; Karson, J.; Wysocki, R.; Lev, E.; Bindeman, I. N.; Kueppers, U.

    2012-12-01

    Lava-ice-snow interactions have recently gained global attention through the eruptions of ice-covered volcanoes, particularly from Eyjafjallajokull in south-central Iceland, with dramatic effects on local communities and global air travel. However, as with most submarine eruptions, direct observations of lava-ice/snow interactions are rare. Only a few hundred potentially active volcanoes are presently ice-covered, these volcanoes are generally in remote places, and their associated hazards make close observation and measurements dangerous. Here we report the results of the first large-scale experiments designed to provide new constraints on natural interactions between lava and ice/snow. The experiments comprised controlled effusion of tens of kilograms of melted basalt on top of ice/snow, and provide insights about observations from natural lava-ice-snow interactions including new constraints for: 1) rapid lava advance along the ice-lava interface; 2) rapid downwards melting of lava flows through ice; 3) lava flow exploitation of pre-existing discontinuities to travel laterally beneath and within ice; and 4) formation of abundant limu o Pele and non-explosive vapor transport from the base to the top of the lava flow with minor O isotope exchange. The experiments are consistent with observations from eruptions showing that lava is more efficient at melting ice when emplaced on top of the ice as opposed to beneath the ice, as well as the efficacy of tephra cover for slowing melting. The experimental extrusion rates are as within the range of those for submarine eruptions as well, and reproduce some features seen in submarine eruptions including voluminous production of gas rich cavities within initially anhydrous lavas and limu on lava surfaces. Our initial results raise questions about the possibility of secondary ingestion of water by submarine and glaciovolcanic lava flows, and the origins of apparent primary gas cavities in those flows. Basaltic melt moving down ice channel over thermocouples (flow approx 30 cm in width).

  1. Sea ice variability during the Holocene: evidence from marine and ice cores in the Ross Sea area, East Antarctica

    NASA Astrophysics Data System (ADS)

    Mezgec, Karin; Melis, Romana; Crosta, Xavier; Traversi, Rita; Severi, Mirko; Colizza, Ester; Braida, Martina; Stenni, Barbara

    2013-04-01

    High latitudes are particularly interesting places to document natural climate variability. Sea ice is an important element in the climate system because it influences bottom water formation and ocean circulation and regulates the ocean-atmosphere heat exchange. Understanding climate and environmental changes through the reconstruction of past sea ice variability, atmospheric circulation and oceanographic conditions in the Southern Ocean could represent one of the most important keys to predict with confidence future climate changes on global scale. In fact, the oceanic area surrounding Antarctica represents the main source of bottom water formation affecting the global climate through the oceanic circulation. In this study, we present an interdisciplinary proxies analysis considering marine and ice core records, as part of the ESF PolarCLIMATE HOLOCLIP (Holocene climate variability at high-southern latitudes: an integrated perspective) project, to document sea ice variability in the Ross Sea continental shelf area. Diatom assemblages from three sediment cores located in the north-western Ross Sea (Joides Basin, Cape Hallett and Wood Bay) have been studied and the sea salt Na+ (a potential proxy of sea ice) records from two ice core sites (Taylor Dome and Talos Dome) facing the Ross Sea area have been considered. The significant positive correlations among the sea ice diatom Fragilariopsis curta relative abundance and sea salt Na+ records from Talos Dome and Taylor Dome ice cores, suggest that sea salt Na+ could be used as a proxy for sea ice extent and/or duration in the Ross Sea area. These preliminary results look as a positive premise in view of integrating proxies from different realms (marine and glacial) in order to achieve a more complete view of the climate and environmental changes occurring during the Holocene. The combination of geological and glacial records will greatly improve our knowledge on paleo sea ice dynamics.

  2. Comparison of automatic segmentation of full polarimetric SAR sea ice images with manually drawn ice charts

    NASA Astrophysics Data System (ADS)

    Moen, M.-A. N.; Doulgeris, A. P.; Anfinsen, S. N.; Renner, A. H. H.; Hughes, N.; Gerland, S.; Eltoft, T.

    2013-06-01

    In this paper we investigate the performance of an algorithm for automatic segmentation of full polarimetric, synthetic aperture radar (SAR) sea ice scenes. The algorithm uses statistical and polarimetric properties of the backscattered radar signals to segment the SAR image into a specified number of classes. This number was determined in advance from visual inspection of the SAR image and by available in-situ measurements. The segmentation result was then compared to ice charts drawn by ice service analysts. The comparison revealed big discrepancies between the charts of the analysts, and between the manual and the automatic segmentations. In the succeeding analysis, the automatic segmentation chart was labeled into ice types by sea ice experts, and the SAR features used in the segmentation were interpreted in terms of physical sea ice properties. Studies of automatic and robust estimation of the number of ice classes in SAR sea ice scenes will be highly relevant for future work.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Last Glacial Maximum to Holocene Sea Ice Decline in the Bering and Chukchi Seas: a Comparison of Diatom-, IP25-, and Grain Size-Based Sea Ice Proxies

    NASA Astrophysics Data System (ADS)

    Caissie, B.; Kocis, J. J.; Nesterovich, A.; Pelto, B. M.; Brigham-Grette, J.

    2014-12-01

    With the rate of Arctic sea ice decline increasing over the past decade, and ice-free conditions in the central Arctic predicted for the second half of this century, it is increasingly important to put sea-ice decline in the context of natural variability. Unfortunately, satellite observations of sea ice only extend back to 1979, and direct observations before then are spotty at best. Recently, there have been several advances in sea ice proxies. Specifically improvements in diatom-based proxies and the molecular biomarker, IP25, have allowed quantitative reconstructions of Arctic sea ice. Here we apply our own IP25 and diatom assemblage sea ice calibrations for the Bering and Chukchi seas to two cores in the Bering Sea that extend to the Last Glacial Maximum in order to explore differences in the proxy records. In addition, we present high-resolution grain size analyses as a way to test the presence or absence of sea ice. Before 14.5 ka, the sediments are composed of up to 20% clay by volume, reflecting transport by sea ice or from a proximal coastline during this time of lowered sea level. IP25 indicates extensive sea ice and the diatom assemblages are dominated by Thalassiosira antarctica and pennate benthic diatoms. Today, T. antarctica is associated with heavy winter and spring sea ice and forms resting spores during an abrupt advance of sea ice in the fall. The pennate benthic taxa include rare instances of IP25-producing species as well as other Naviculoid species that are commonly found attached to spring sea ice. Between 14.5 and 12 ka, clay sized particles make up only 8% of the sediments and IP25 indicates that sea ice was absent from both locations. However, diatoms commonly found in the marginal ice zone today such as Fragilariopsis spp. Thalassiosira hyalina, and Thalassiosira nordenskioeldii are common. Sea ice was extensive (up to 60% annual coverage) at both sites during the Last Glacial Maximum and it declined during the deglaciation. IP25 indicates that sea ice was absent at both sites after 14.5 ka, except for a minor advance during the Younger Dryas. However, in contrast, diatom assemblages indicate that sea ice was present until 11 ka. We hypothesize that two different ice conditions existed, with the more recent ice unsuitable for IP25-producers.

  8. Ice-associated phytoplankton blooms in the southeastern Bering Sea Meibing Jin,1

    E-print Network

    Ice-associated phytoplankton blooms in the southeastern Bering Sea Meibing Jin,1 Clara Deal,1 Jia 2007. [1] Ice-associated phytoplankton blooms in the south- eastern Bering Sea can critically impact-associated blooms were seeded by sea ice algae released from melting sea ice. For an ice-associated bloom to grow

  9. MISR Cloud Detection over Ice and Snow Based on Linear Correlation Matching

    Microsoft Academic Search

    Tao Shi; Bin Yu; Amy Braverman

    Cloud detection is a crucial step in any climate modelling or prediction. Multi-angle Imaging SpectroRadiometer (MISR) was launched in 1999 by NASA to provide 9 angle and 4 band data to retrieve or estimate the cloud height and hence cloud detection. However, cloud detection even with MISR data has been proven very di-cult over ice and snow. In this paper,

  10. All About Snow

    NSDL National Science Digital Library

    This National Snow and Ice Data Center website presents a variety of general information about snow. It includes a question and answer section, which explains why snow is white, and the difficulties of forecasting snow, for example. There is a snow fact sheet, a glossary for snow terminology and weather terms, and a photo gallery of snow storms, ice storms, blizzards, avalanches, and other snow phenomena and formations.

  11. On detection of the thermophysical state of landfast first-year sea ice using in-situ microwave emission during spring melt

    Microsoft Academic Search

    Byong Jun Hwang; Alexandre Langlois; David G. Barber; Timothy N. Papakyriakou

    2007-01-01

    In this study we examine the critical linkages between thermophysical properties and microwave emissions of landfast snow-covered first-year sea ice during spring melt. For this we analyzed the temporal evolution of radiation fluxes, electro-thermophysical properties and microwave emissions, and perform model simulations to evaluate the observations. The results show five major microwave signature events: brine-rich, blowing snow, melt onset, the

  12. Climate and sea ice variability in the SW Labrador Sea during the late Holocene

    NASA Astrophysics Data System (ADS)

    Weckström, Kaarina; Massé, Guillaume; Collins, Lewis; Sicre, Marie-Alexandrine; Bouloubassi, Ioanna; Seidenkrantz, Marit-Solveig; Olsen, Jesper; Kuijpers, Antoon

    2014-05-01

    The recent rapid decline in Arctic sea ice cover has increased the need to improve the accuracy of the sea ice components in climate models and to provide detailed long-term sea ice records based on proxy data. Recently, the highly branched isoprenoid IP25 has emerged as a potential sea ice specific proxy for past sea ice cover, found in marine sediments underlying seasonal sea ice. We tested the reliability of this biomarker against observational sea ice data off Newfoundland (SW Labrador Sea), where box cores covering the last ca. 100-150 years were collected. Based on the results, IP25 proved to be a robust and reliable proxy for reconstructing variability in past sea ice concentrations in the area. After having successfully validated the proxy in the SW Labrador Sea, we further analysed IP25 from a sediment core NE of Newfoundland covering the last ca. 5000 years, providing the southernmost multi-millennial record of this proxy to date. Based on this record and on diatom and dinoflagellate cyst data and alkenone-based sea surface temperatures (SSTs) from the same core, we reconstructed climatic conditions in and Arctic sea ice export to the SW Labrador Sea area: Alkenone-based SSTs show a clear albeit variable decline after the Holocene Climate Optimum, while at the same time diatom and dinoflagellate cyst data suggest decreased melt water export from the Arctic. The IP25 record reveals increased sea ice export from the Baffin and Hudson Bays starting ca 1500 yr cal. BP, accelerating ca. 800 yr cal. BP and culminating at the height of the Little Ice Age. Sea ice export during the last century is comparable to the export during the Medieval Climate Anomaly.

  13. Sea ice cover in the Caspian and Aral Seas from historical and satellite data

    Microsoft Academic Search

    Alexei V. Kouraev; Fabrice Papa; Nelly M. Mognard; Petr I. Buharizin; Anny Cazenave; Jean-francois Cretaux; Julia Dozortseva; Frederique Remy

    2004-01-01

    Abstract Time and space variations of ice cover in the Caspian and Aral Seas from historical and satellite data are discussed. Existing published continuous time series of ice cover parameters for these seas stop in 1984–1985; the results of observations for later periods are heterogeneous and mostly unpublished. The current lack of time series for ice cover parameters since the

  14. Shipborne electromagnetic induction sounding of sea-ice thickness in the southern Sea of Okhotsk

    Microsoft Academic Search

    Shotaro Uto; Takenobu Toyota; Haruhito Shimoda; Kazutaka Tateyama; Kunio Shirasawa

    2006-01-01

    Recent observations have revealed that dynamical thickening is dominant in the growth process of sea ice in the southern Sea of Okhotsk. That indicates the importance of understanding the nature of thick deformed ice in this area. The objective of the present paper is to establish a ship-based method for observing the thickness of deformed ice with reasonable accuracy. Since

  15. 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.

  16. Studies of Sea-ice Motion in tlheLaptev Sea withlthe use of Satellite Remote Sensing and Numerical Modelling

    E-print Network

    Eicken, Hajo

    Studies of Sea-ice Motion in tlheLaptev Sea withlthe use of Satellite Remote Sensing and Numerical and interannual variability of ice drifi in the Laptev Sea and ice exchange with the A~ctic Ocean have been investigated using remote sensing data, a large-scale dynamic-thermodynamic numerical sea ice model and semi

  17. 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.

  18. 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.

  19. Increasing Arctic sea ice export driven by stronger winds

    NASA Astrophysics Data System (ADS)

    Sorteberg, A.; Smedsrud, L. H.; Sirevaag, A.; Kloster, K.

    2010-12-01

    Arctic sea ice area has decreased steadily over the last three decades. A thinner and more seasonal Arctic ice cover, related to increased long wave radiation, has become evident. Changes in circulation, including drift patterns of the Arctic pack ice, have been less obvious. Arctic sea ice export estimates have been hampered by low resolution spatial and temporal satellite imagery, especially during summer, making accurate detection difficult. Here we present a new ice area export dataset calculated from sea ice motion and concentration profiles along 79N. Ice drift vectors are calculated from ice feature displacement using Envisat ASAR WideSwath images every 3 days from 2004 while ice concentration is based on DMSP F13 SSMI and AQUA AMSR-E brightness temperature data. The two data sets are combined to give the ice-area flux in consecutive 3-day periods, uninterrupted year-round coverage along 79N. It is shown that sea ice export variability is closely linked to the geostrophic wind in the Fram Strait (correlation of 0.84). Using geostrophic winds from reanalysis back to the 1950s as a proxy for ice export indicates that the Arctic sea ice has annually lost an increasing area since the 1950's driven by stronger winds. Ice concentration has decreased slightly, but does not contribute significantly. The ice export has overall increased by ~25% over the period. Using cyclone tracking the changes in winds seems directly related to a higher low pressure activity in the Nordic Seas. Our results demonstrate that the changes in atmospheric circulation over the Arctic and sub-Arctic have contributed to a trend in the Fram Strait ice export. The Fram Strait between Greenland and Svalbard with average sea ice concentration for summer (red, June through August) and winter (black, January through March). Solid lines are 50%, dashed lines are 15%. Above mean southward ice drift across 79N from August 2004 to July 2010 in 1 degree bins based on SAR imagery, and mean ice concentration from SSMI data. The ice area export is found by multiplying the ice drift and ice concentrations. Yellow circles show locations for surface pressure data used.

  20. Albedo changes of the Arctic sea ice cover

    Microsoft Academic Search

    D. K. Perovich; B. Light; K. F. Jones; H. Eicken; K. Runciman; S. V. Nghiem; J. Stroeve; T. Markus

    2008-01-01

    The summer extent of the Arctic sea ice cover has decreased in recent decades and there have been alterations in the timing and duration of the summer melt season. This has resulted in changes in the evolution of albedo of the Arctic sea ice cover, and consequently in the partitioning of solar energy. These changes are examined on a pan-Arctic

  1. SAR Sea Ice Discrimination Using Texture Statistics: A Multivariate Approach

    Microsoft Academic Search

    David G. Barber; Ellsworth F. LeDrew

    1991-01-01

    Discrimination of sea ice classes using texture statistics derived from the conditional joint probability density functions of the grey level Co-occurrence matrix (GLCM) is reported on. Univariate and multivariate analyses are used to describe the separability of synthetic aperture radar (SAR) sea ice feature space. Impact of the conditional parameters (interpixel sampling distance) and a (orientation), and the effect of

  2. Towards an Ice-free Northern Sea Route?

    Microsoft Academic Search

    J. M. Rodrigues

    2006-01-01

    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

  3. Inversion algorithms for remote sensing of sea ice

    Microsoft Academic Search

    M. E. Veysoglu; H. T. Ewe; A. K. Jordan; R. T. Shin; J. A. Kong

    1994-01-01

    In certain cases available electromagnetic measurements may not contain sufficient information to reconstruct sea ice parameters such as thickness, extent or concentration. In this study it is shown that by incorporating additional information provided by dynamical equations governing sea ice physics, the electromagnetic inverse problem can be constrained sufficiently to achieve more accurate reconstructions. To accomplish this, the time series

  4. Sea Ice Detection Using EnviSAT Radar Altimeter 2

    NASA Astrophysics Data System (ADS)

    Rinne, E. J.; Skourup, H.

    2012-12-01

    We present a novel method for sea ice detection using Radar Altimeter 2 (RA-2) data and examples of RA-2 based ice extent maps along the Northern Sea Route during the navigation season of 2011. This work is the first step in utilizing satellite altimeter data in operational ice charting. We also present a cross-comparison of our RA2 data and the Multisensor Analyzed Sea Ice Extent - Northern Hemisphere (MASIE-NH) product. As the sea ice recedes due to warming climate, new shipping routes open. The number of ships navigating the Northern Sea Route is expected to increase rapidly. This calls for accurate ice information services and ice charts. Most widely used Earth Observation data in ice charting for navigation are Synthetic Aperture Radar (SAR) images. Other instruments such as altimeters provide valuable additional information on ice conditions. The altimeter data would complement the SAR images and provide independent validation of operational ice charts. Our method is based on the heterogeneous nature of sea ice. We exploit the standard deviation of 18 Hz Ku-band ocean backscatter coefficient (SD sigma-0) present in the RA-2 SGDR products. In comparison to open water, sea ice exhibits large spatial variability in a variety of scales. In consequence the SD sigma-0 is high when sea ice is present. Using a simple threshold we classify areas of high SD sigma-0 sea ice covered. The comparison of RA-2 detected sea ice and MASIE-NH product shows good agreement. Our method is considerably simpler than the method to derive ice thickness from altimeter measurements. In consequence our method would be easy to implement in operational ice charting systems. The work here is a proof-of-concept that satellite altimeters can be used to provide information to support ice charting. The results are based on archived data, but there is no reason why similar approach would not work with the current generation of radar altimeters on board Cryosat-II and the future Sentinel-3 satellites.

  5. Thin and thinner: Sea ice mass balance measurements during SHEBA

    Microsoft Academic Search

    Donald K. Perovich; Thomas C. Grenfell; Jacqueline A. Richter-Menge; Bonnie Light; Walter B. Tucker III; Hajo Eicken

    2003-01-01

    As part of a large interdisciplinary study of the Surface Heat Budget of the Arctic Ocean (SHEBA), we installed more than 135 ice thickness gauges to determine the sea ice mass balance. While installing these gauges during the fall of 1997, we found that much of the multiyear ice cover was only 1 m thick, considerably thinner than expected. Over

  6. Thin and thinner: Sea ice mass balance measurements during SHEBA

    Microsoft Academic Search

    Donald K. Perovich; Thomas C. Grenfell; Jacqueline A. Richter-Menge; Bonnie Light; Walter B. Tucker III; Hajo Eicken

    2001-01-01

    (1) As part of a large interdisciplinary study of the Surface Heat Budget of the Arctic Ocean (SHEBA), we installed more than 135 ice thickness gauges to determine the sea ice mass balance. While installing these gauges during the fall of 1997, we found that much of the multiyear ice cover was only 1 m thick, considerably thinner than expected.

  7. An Elastic–Viscous–Plastic Model for Sea Ice Dynamics

    Microsoft Academic Search

    E. C. Hunke; J. K. Dukowicz

    1997-01-01

    The standard model for sea ice dynamics treats the ice pack as a visco-plastic material that flows plastically under typical stress conditions but behaves as a linear viscous fluid where strain rates are small and the ice becomes nearly rigid. Because of large viscosities in these regions, implicit numerical methods are necessary for time steps larger than a few seconds.

  8. An unstructuredgrid, finitevolume sea ice model: Development, validation, and application

    E-print Network

    Chen, Changsheng

    finitevolume solver. Implementing UGCICE into the Arctic Ocean finitevolume community ocean model provides a new unstructuredgrid, MPIparallelized model system to resolve the iceocean interaction dynamics of the sea ice concentration, ice coverage, and ice drifting in the Arctic Ocean and adjacent coastal regions

  9. 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.

  10. In situ measurements of the direct-current conductivity of Antarctic sea ice: implications for airborne electromagnetic sounding of sea-ice thickness

    Microsoft Academic Search

    J. E. Reid; A. Pfaffling; A. P. Worby; J. R. Bishop

    2006-01-01

    Airborne, ship-borne and surface low-frequency electromagnetic (EM) methods have become widely applied to measure sea-ice thickness. EM responses measured over sea ice depend mainly on the sea-water conductivity and on the height of the sensor above the sea-ice-sea-water interface, but may be sensitive to the sea-ice conductivity at high excitation frequencies. We have conducted in situ measurements of direct-current conductivity

  11. 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.

  12. Zooplankton boom and ice amphipod bust below melting sea ice in the Amundsen Gulf, Arctic Canada

    Microsoft Academic Search

    Haakon Hop; Christopher J. Mundy; Michel Gosselin; Andrea L. Rossnagel; David G. Barber

    Early summer in the Arctic with extensive ice melt and break-up represents a dramatic change for sympagic–pelagic fauna below\\u000a seasonal sea ice. As part of the International Polar Year-Circumpolar Flaw Lead system study (IPY-CFL), this investigation\\u000a quantified zooplankton in the meltwater layer below landfast ice and remaining ice fauna below melting ice during June (2008)\\u000a in Franklin Bay and Darnley

  13. The seasonal evolution of sea ice motion in the Beaufort Sea and the ice packs response to atmospheric forcing

    NASA Astrophysics Data System (ADS)

    Babb, D.; Lukovich, J. V.; Scharien, R. K.; Galley, R. J.; Barber, D. G.

    2014-12-01

    Through spring the ice pack of the Beaufort Sea transitions from an extensive, consolidated ice state in late winter to a less extensive, weaker, marginal ice zone in summer. Using an array of autonomous instruments deployed in early April 2012 along the periphery of the multiyear ice pack, we highlight the seasonal evolution of ice drift as the ice pack broke up and individual ice floes entered a state of free drift. Coincident hourly observations of ice drift, surface winds, and ice mass balance were collected from early April to the end of July 2012 when the autonomous equipment failed. During this period ice drift speeds tripled, meander coefficients increased, ice drift became less correlated across increasingly small length scales, inertial oscillations developed along the ice floe trajectories and ice floes became increasingly responsive to surface winds, as indicated by increasing scaling factors and turning angles. Given that monthly mean wind speeds remained around 4 m/s throughout the study, we ascribe the seasonal change in ice drift characteristics to the seasonal mechanical weakening of the ice pack. Using a combination of in situ and remotely sensed observations we highlight the seasonal decline of local and regional ice concentrations, declining ice floe flexural strengths, substantial surface melt and bottom ablation and a seasonal tendency towards smaller floe sizes. Collectively these observations represent the mechanical weakening of the ice pack which fostered a seasonal increase in the responsiveness of the ice pack to atmospheric forcing.

  14. Sea ice investigations in the Laptev Sea using RADARSAT ScanSAR data

    Microsoft Academic Search

    S. Sandven; M. Lundhaug; O. Dalen; J. Solhaug; K. Kloster; V. Alexandrov; V. V. Melentyev; A. Bogdanov

    1998-01-01

    During a field expedition with the Russian nuclear icebreaker “Sovetsky Soyuz” to the Laptev Sea in September 1997, RADARSAT ScanSAR images were used to investigate late summer ice conditions and support ice navigation. The predominant ice types were first year and newly formed ice, primarily nilas. The in situ observations made from the icebreaker and its helicopter were used to

  15. Nonlinear threshold behavior during the loss of Arctic sea ice

    E-print Network

    Eisenman, I; 10.1073/pnas.0806887106

    2008-01-01

    In light of the rapid recent retreat of Arctic sea ice, a number of studies have discussed the possibility of a critical threshold (or "tipping point") beyond which the ice-albedo feedback causes the ice cover to melt away in an irreversible process. The focus has typically been centered on the annual minimum (September) ice cover, which is often seen as particularly susceptible to destabilization by the ice-albedo feedback. Here we examine the central physical processes associated with the transition from ice-covered to ice-free Arctic Ocean conditions. We show that while the ice-albedo feedback promotes the existence of multiple ice cover states, the stabilizing thermodynamic effects of sea ice mitigate this when the Arctic Ocean is ice-covered during a sufficiently large fraction of the year. These results suggest that critical threshold behavior is unlikely during the approach from current perennial sea ice conditions to seasonally ice-free conditions. In a further warmed climate, however, we find that a ...

  16. 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.

  17. 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

  18. 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.

  19. North Atlantic warming and declining volume of arctic sea ice

    NASA Astrophysics Data System (ADS)

    Alexeev, V. A.; Ivanov, V. V.; Kwok, R.; Smedsrud, L. H.

    2013-01-01

    Long-term thinning of arctic sea ice over the last few decades has resulted in significant declines in the coverage of thick multi-year ice accompanied by a proportional increase in thinner first-year ice. This change is often attributed to changes in the arctic atmosphere, both in composition and large-scale circulation, and greater inflow of warmer Pacific water through the Bering Strait. The Atlantic Water (AW) entering the Arctic through Fram Strait has often been considered less important because of strong stratification in the Arctic Ocean and the deeper location of AW compared to Pacific water. In our combined examination of oceanographic measurements and satellite observations of ice concentration and thickness, we find evidence that AW has a direct impact on the thinning of arctic sea ice downstream of Svalbard Archipelago. The affected area extends as far as Severnaya Zemlya Archipelago. The imprints of AW appear as local minima in sea ice thickness; ice thickness is significantly less than that expected of first-year ice. Our lower-end conservative estimates indicate that the recent AW warming episode could have contributed up to 150-200 km3 of sea ice melt per year, which would constitute about 20% of the total 900 km3yr-1 negative trend in sea ice volume since 2004.

  20. 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.

  1. Evidence of Arctic sea ice thinning from direct observations

    NASA Astrophysics Data System (ADS)

    Renner, Angelika H. H.; Gerland, Sebastian; Haas, Christian; Spreen, Gunnar; Beckers, Justin F.; Hansen, Edmond; Nicolaus, Marcel; Goodwin, Harvey

    2014-07-01

    The Arctic sea ice cover is rapidly shrinking, but a direct, longer-term assessment of the ice thinning remains challenging. A new time series constructed from in situ measurements of sea ice thickness at the end of the melt season in Fram Strait shows a thinning by over 50% during 2003-2012. The modal and mean ice thickness along 79°N decreased at a rate of 0.3 and 0.2 m yr-1, respectively, with long-term averages of 2.5 and 3 m. Airborne observations reveal an east-west thickness gradient across the strait in spring but not in summer due to advection from more different source regions. There is no clear relationship between interannual ice thickness variability and the source regions of the ice. The observed thinning is therefore likely a result of Arctic-wide reduction in ice thickness with a potential shift in exported ice types playing a minor role.

  2. Inorganic carbon dynamics of melt-pond-covered first-year sea ice in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Geilfus, N.-X.; Galley, R. J.; Crabeck, O.; Papakyriakou, T.; Landy, J.; Tison, J.-L.; Rysgaard, S.

    2015-03-01

    Melt pond formation is a common feature of spring and summer Arctic sea ice, but the role and impact of sea ice melt and pond formation on both the direction and size of CO2 fluxes between air and sea is still unknown. Here we report on the CO2-carbonate chemistry of melting sea ice, melt ponds and the underlying seawater as well as CO2 fluxes at the surface of first-year landfast sea ice in the Resolute Passage, Nunavut, in June 2012. Early in the melt season, the increase in ice temperature and the subsequent decrease in bulk ice salinity promote a strong decrease of the total alkalinity (TA), total dissolved inorganic carbon (TCO2) and partial pressure of CO2 (pCO2) within the bulk sea ice and the brine. As sea ice melt progresses, melt ponds form, mainly from melted snow, leading to a low in situ melt pond pCO2 (36 ?atm). The percolation of this low salinity and low pCO2 meltwater into the sea ice matrix decreased the brine salinity, TA and TCO2, and lowered the in situ brine pCO2 (to 20 ?atm). This initial low in situ pCO2 observed in brine and melt ponds results in air-ice CO2 fluxes ranging between -0.04 and -5.4 mmol m-2 day-1 (negative sign for fluxes from the atmosphere into the ocean). As melt ponds strive to reach pCO2 equilibrium with the atmosphere, their in situ pCO2 increases (up to 380 ?atm) with time and the percolation of this relatively high concentration pCO2 meltwater increases the in situ brine pCO2 within the sea ice matrix as the melt season progresses. As the melt pond pCO2 increases, the uptake of atmospheric CO2 becomes less significant. However, since melt ponds are continuously supplied by meltwater, their in situ pCO2 remains undersaturated with respect to the atmosphere, promoting a continuous but moderate uptake of CO2 (~ -1 mmol m-2 day-1) into the ocean. Considering the Arctic seasonal sea ice extent during the melt period (90 days), we estimate an uptake of atmospheric CO2 of -10.4 Tg of C yr-1. This represents an additional uptake of CO2 associated with Arctic sea ice that needs to be further explored and considered in the estimation of the Arctic Ocean's overall CO2 budget.

  3. Observation of melt onset on multiyear Arctic sea ice using the ERS 1 synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Winebrenner, D. P.; Nelson, E. D.; Colony, R.; West, R. D.

    1994-01-01

    We present nearly coincident observations of backscattering from the Earth Remote-Sensing Satellite (ERS) 1 synthetic aperture radar (SAR) and of near-surface temperature from six drifting buoys in the Beaufort Sea, showing that the onset of melting in snow on multiyear sea ice is clearly detectable in the SAR data. Melt onset is marked by a clean, steep decrease in the backscattering cross section of multiyear ice at 5.3 GHz and VV polarization. We investigate the scattering physics responsible for the signature change and find that the cross section decrease is due solely to the appearance of liquid water in the snow cover overlying the ice. A thin layer of moist snow is sufficient to cause the observed decrease. We present a prototype algorithm to estimate the date of melt onset using the ERS 1 SAR and apply the algorithm first to the SAR data for which we have corresponding buoy temperatures. The melt onset dates estimated by the SAR algorithm agree with those obtained independently from the temperature data to within 4 days or less, with the exception of one case in which temperatures oscillated about 0 C for several weeks. Lastly, we apply the algorithm to the entire ERS 1 SAR data record acquired by the Alaska SAR Facility for the Beaufort Sea north of 73 deg N during the spring of 1992, to produce a map of the dates of melt onset over an area roughly 1000 km on a side. The progression of melt onset is primarily poleward but shows a weak meridional dependence at latitudes of approximately 76 deg-77 deg N. Melting begins in the southern part of the study region on June 13 and by June 20 has progressed to the northermost part of the region.

  4. Tracking the Record Sea Ice Minimum in the Arctic Using National Ice Center Charts

    NASA Astrophysics Data System (ADS)

    Woods, J.; Clemente-Colón, P.; Brinkley, J.; Helfrich, S.; Huang, W.; Melchior, B.; Arbetter, T.

    2007-12-01

    The National/Naval Ice Center (NIC), in Suitland, MD, produces routine analyses of sea ice coverage in the Arctic. We create a Northern Hemispheric analyses based on bi-weekly charts for over 30 individual areas. Weekly charts of several key areas such as the High Arctic, Beaufort Sea, Chukchi Sea, North Sea, and Kara Sea are also produced. To create these charts, analysts at the NIC pool all available data sources including satellite imagery, buoy and shipboard in-situ observations, and models. During the 2007 sea ice season, the NIC charts confirmed observations from other groups (e.g, NSIDC Sea Ice Index, JPL QuikSCAT) that the previous Arctic sea ice minimum recorded in September 2005 was surpassed. NIC charts were also used to monitor the navigability of the both the Northwest Passage and Northern Sea Routes, which are historically ice-infested. Using the NIC sea ice climatology database shows that the routes reached levels of "openness" in 2007 which have not been observed in recent history.

  5. 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.

  6. 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.

  7. On the brine drainage and algal uptake controls of the nutrient supply to the sea ice interior

    NASA Astrophysics Data System (ADS)

    Vancoppenolle, M.; Goosse, H.; de Montety, A.; Fichefet, T.; Tison, J.-L.

    2009-04-01

    Sea ice ecosystems are important components of the biogeochemical cycles (including carbon) and hence have a potential impact on climate. They are characterized by large stocks of micro-algae. Those algae (mostly diatoms) live in liquid inclusions of saline brine, which are encased within the solid ice matrix and require sustained nutrient supply to grow. In this study, we investigate the interactions between nutrients, brine motion and algal growth, using a one-dimensional (1D) sea ice model. The model includes (i) a classical formulation for snow and ice thermodynamics with explicit, reformulated brine physics and (ii) an idealized sea ice biological component, characterized by one single nutrient, namely dissolved silica (DSi), which stocks are reduced by a prescribed primary production. DSi is considered as a passive tracer dissolved within brine following fluid motion. The brine flow regime (advective, diffusive or turbulent) is computed as a function of environmental ice conditions. In winter, a Rayleigh number proposed by Notz and Worster (2008) is used to differentiate diffusion and convection. Ice salinity and DSi concentrations within the ice are solutions of 1D advection-diffusion equations over the variable volume brine network domain. The model is configured for a typical year of seasonal Weddell Sea ice. The simulated vertical salinity and tracer profiles as well as ice-ocean salt fluxes realistically agree with observations. Complex bio-physical interactions are simulated by the model. Analysis highlights the role of convection in the lowermost 5-10 cm of ice (gravity drainage), mixing highly saline, nutrient-depleted brine with comparatively fresh, nutrient-rich seawater. Hence, gravity drainage rejects salt to the ocean and provides nutrients to the ice interior. In turn, primary production and brine convection act synergetically to form a nutrient pump, which enhances the net ocean-to-ice DSi flux by 20-115%, compared to an abiotic situation. The other important simulated processes are winter and spring surface flooding of seawater which supplies nutrients near the ice surface, and melt water percolation which - if present in reality - would tend to flush nutrients back to the ocean in summer. The physical background for sea ice tracers developed here is general and could be used to simulate other sea ice tracers (e.g., dissolved organic matter, isotopes, gases, radio-nuclides, ...), constituting an improved modelling strategy for sea ice brine and ecosystem dynamics.

  8. Antarctic sea ice carbon dioxide system and controls

    NASA Astrophysics Data System (ADS)

    Fransson, Agneta; Chierici, Melissa; Yager, Patricia L.; Smith, Walker O., Jr.

    2011-12-01

    In austral summer, from December 2008 to January 2009, we investigated the sea-ice carbon dioxide (CO2) system and CO2 controls in the Amundsen and Ross Seas, Antarctica. We sampled seawater, brine and sea ice for the measurements of total alkalinity (AT), total inorganic carbon (DIC), pH, inorganic nutrients, particulate organic carbon (POC) and nitrogen (PON), chlorophyll a, pigments, salinity and temperature. Large variability in all measured parameters was observed in time and space due to the complex sea-ice dynamics. We discuss the controls of the sea-ice CO2 system, such as brine rejection, biological processes, calcium carbonate (CaCO3) precipitation/dissolution and CO2 exchange. Most (80 to 90%) of the DIC loss was due to brine rejection, which suggests that the sea ice acted as an efficient DIC sink from 0.8 and 2.6 mol m-2 yr-1 (9.6-31 g C m-2 yr-1). The remaining change in DIC was to a large extent explained by net biological production. The AT:DIC ratio in the sea ice was higher than in the under-ice water (UIW), with ratios reaching 1.7, which indicated CaCO3 precipitation and concomitant DIC loss in the sea ice. Elevated AT:DIC ratios and carbonate concentrations were also observed in the UIW, which reflect the solid CaCO3 rejected from the ice during melt. The potential for uptake of atmospheric CO2 in the mixed layer increased by approximately 56 ?atm due to the combined effect of CaCO3 precipitation during ice formation, and ice melt in summer.

  9. The Role of Sea Ice in 2×CO2 Climate Model Sensitivity. Part I: The Total Influence of Sea Ice Thickness and Extent

    Microsoft Academic Search

    D. Rind; R. Healy; C. Parkinson; D. Martinson

    1995-01-01

    As a first step in investigating the effects of sea ice changes on the climate sensitivity to doubled atmospheric CO2, the authors use a standard simple sea ice model while varying the sea ice distributions and thicknesses in the control run. Thinner ice amplifies the atmospheric temperature sensitivity in these experiments by about 15% (to a warming of 4.8°C), because

  10. Measured and modeled albedos of sea-ice surfaces with implications for Snowball Earth

    NASA Astrophysics Data System (ADS)

    Carns, Regina C.

    The Snowball Earth episodes were extensive glaciations that occurred during the Neoproterozoic, between 600 and 800 million years ago, during which ice covered much or all of the oceans. These glaciations were a result of ice-albedo feedback, a process likely to occur on any Earthlike planet with oceans covering most of its surface. Modeling shows that sublimation would exceed precipitation over large regions of the ice-covered ocean on a Snowball planet; during the initial stages of the Snowball episode, these areas would be entirely covered by sea ice containing inclusions of brine, and sea ice could remain in smaller regions through the whole episode. At temperatures likely to prevail in the Snowball climate, sodium chloride precipitates within brine inclusions as the hydrated salt hydrohalite (NaCl·2H2O, also known as sodium chloride dehydrate). This work used field measurements, laboratory experiments and modeling to constrain the albedo of sea ice surfaces relevant to Snowball Earth. Field measurements of cold sea ice in McMurdo Sound show an increase in the albedo of natural sea ice with decreasing temperatures. Laboratory experiments on natural sea ice show that brine pockets can become supersaturated with respect to sodium chloride at low temperatures, creating a hysteresis in hydrohalite precipitation and dissolution. Experiments show this effect in laboratory-grown ice of several different compositions: grown from an NaCl solution, grown from artificial seawater, and grown from artificial seawater with added extracellular polysaccharides. Sufficiently cold sea ice in a region of net sublimation will eventually develop a lag deposit of salt as the ice sublimates away from precipitated hydrohalite in brine pockets. No sea ice on modern Earth stays cold and dry long enough for such a deposit to form, so we developed a method for measuring the albedo of ice surfaces in a cold-room laboratory. The method uses a dome with a diffusely reflecting interior surface to emulate the light from an overcast sky. We created a crust of hydrohalite and used this "albedo dome" method to measure albedo of the crust as it developed and dissolved. Using these measurements along with a radiative transfer code, we inferred the complex refractive index for hydrohalite and developed a parameterization for the albedo of hydrohalite crusts of any thickness. These results have implications for Earthlike exoplanets with sizable oceans, which would also be susceptible to ice-albedo feedback. The formation of hydrohalite in sub-eutectic sea ice and the development of a lag deposit in cold, dry conditions could intensify the positive feedback that leads to Snowball conditions. This work shows that the albedo of hydrohalite is much higher than that of snow in the near-infrared, which could make the formation of hydrohalite crusts particularly important to the climates of planets that orbit M-dwarf stars, which output a large fraction of their energy in the near-infrared.

  11. GNSS-R ground-based and airborne campaigns for ocean, land, ice, and snow techniques: Application to the GOLD-RTR data sets

    NASA Astrophysics Data System (ADS)

    Cardellach, E.; Fabra, F.; NoguéS-Correig, O.; Oliveras, S.; Ribó, S.; Rius, A.

    2011-12-01

    Several ground-based and airborne data sets taken with the Global Navigation Satellite System Reflectometry (GNSS-R) technique are made available to the research community. This paper reviews the potential applications of these bistatic radar observations, including a list of possible approaches and algorithms described in the literature for oceanic measurements (altimetric and scatterometric), soil moisture sensing, and sea ice and snow characterization. A list of applicable models complements the review. The paper continues with descriptions of the campaigns included in the initial data set, together with the basic information required to understand the instrumental issues of the data. Finally, some parameters and observables provided in the data are detailed.

  12. Mesoscale distribution and functional diversity of picoeukaryotes in the first-year sea ice of the Canadian Arctic

    PubMed Central

    Piwosz, Kasia; Wiktor, Józef Maria; Niemi, Andrea; Tatarek, Agnieszka; Michel, Christine

    2013-01-01

    Sea ice, a characteristic feature of polar waters, is home to diverse microbial communities. Sea-ice picoeukaryotes (unicellular eukaryotes with cell size <3??m) have received little attention compared with diatoms that dominate the spring bloom in Arctic first-year sea ice. Here, we investigated the abundance of all picoeukaryotes, and of 11 groups (chlorophytes, cryptophytes, bolidophytes, haptophytes, Pavlovaphyceae, Phaeocystis spp., pedinellales, stramenopiles groups MAST-1, MAST-2 and MAST-6 and Syndiniales Group II) at 13 first-year sea-ice stations localized in Barrow Strait and in the vicinity of Cornwallis Island, Canadian Arctic Archipelago. We applied Catalyzed Reporter Deposition–Fluorescence In Situ Hybridization to identify selected groups at a single cell level. Pavlovaphyceae and stramenopiles from groups MAST-2 and MAST-6 were for the first time reported from sea ice. Total numbers of picoeukaryotes were significantly higher in the vicinity of Cornwallis Island than in Barrow Strait. Similar trend was observed for all the groups except for haptophytes. Chlorophytes and cryptophytes were the dominant plastidic, and MAST-2 most numerous aplastidic of all the groups investigated. Numbers of total picoeukaryotes, chlorophytes and MAST-2 stramenopiles were positively correlated with the thickness of snow cover. All studied algal and MAST groups fed on bacteria. Presence of picoeukaryotes from various trophic groups (mixotrophs, phagotrophic and parasitic heterotrophs) indicates the diverse ecological roles picoeukaryotes have in sea ice. Yet, >50% of total sea-ice picoeukaryote cells remained unidentified, highlighting the need for further study of functional and phylogenetic sea-ice diversity, to elucidate the risks posed by ongoing Arctic changes. PMID:23514779

  13. Global Fiducials Program - Arctic Buoy Sea Ice Studies

    NASA Astrophysics Data System (ADS)

    Wilson, E. M.; Wilds, S. R.; Friesen, B. A.; Sloan, J. L.

    2012-12-01

    The U.S. Geological Survey has utilized remotely sensed imagery to analyze Arctic Sea Ice since 1997, and has collected and created thousands of Literal Image Derived Products (LIDPS) at one meter resolution for public distribution. From 1997-2012, six static sea ice sites located in the Arctic Basin were selected and added to the Global Fiducial Library (GFL), to create an annual series of geographically referenced images to allow scientists to study seasonal changes in Arctic ice. In early 2009, a scientific group known as MEDEA (Measurements of Earth Data for Environmental Analysis) requested additional collections to track ice floe movements during the course of an entire summer (April through September), to better understand seasonal changes in the Arctic Sea Ice. In order to track and capture the same ice cover over time, USGS adopted a methodology to utilize buoys deployed at various locations across the Arctic by the International Arctic Buoy Program. The data buoys record and transmit hourly GPS positions, along with meteorologic and climatologic data associated with the sea ice in which they are anchored. Repeated imaging of the ice cover is guided by the data buoy GPS to help estimate travel direction and speed of the ice cover. Imagery is referenced by the MEDEA scientists to study ice fracture patterns, sea ice ridge heights, ice cover percentages, seasonal development and coverage of melt ponds, evolution of ice concentrations, floe size distribution, lateral melting, and other variables that are used for input to refine and develop climate models. These same ice floe images have been added to the GFL for various buoy locations from 2009 through 2011, and are being acquired for the 2012 summer season.

  14. Arctic sea ice melt in summer 2007: Surface and bottom ice ablation

    Microsoft Academic Search

    D. K. Perovich; J. A. Richter-Menge; B. C. Elder; K. J. Claffey

    2007-01-01

    Satellite observations indicate a record minimum in Arctic sea ice extent in September 2007, with a particularly large retreat in the East Siberian, Chukchi, and Beaufort Seas. Insights on the nature of this retreat, and of the summer melt season, can be gleaned from 7 autonomous buoys that were monitoring the thermodynamic mass balance of the ic