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1

MODIS Snow and Sea Ice Products  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

2

Microwave remote sensing of snow-covered sea ice  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

3

Antarctic sea ice thickness and snow-to-ice conversion from atmospheric reanalysis and passive microwave snow depth  

Microsoft Academic Search

Passive microwave snow depth, ice concentration, and ice motion estimates are combined with snowfall from the European Centre for Medium-Range Weather Forecasting (ECMWF) reanalysis (ERA-40) from 1979–2001 to estimate the prevalence of snow-to-ice conversion (snow-ice formation) on level sea ice in the Antarctic for April–October. Snow ice is ubiquitous in all regions throughout the growth season. Calculated snow-ice thicknesses fall

Ted Maksym; Thorsten Markus

2008-01-01

4

Interactions between snow and melt ponds in sea ice models  

NASA Astrophysics Data System (ADS)

Snow cover on sea ice at the end of the winter persists into the early part of the sea ice melt season, and the spatial distribution of snow affects the surface topography, the distribution of initial melt pond formation and its subsequent evolution. After the initial formation of melt ponds, the low albedo of the ponds compared to snow or bare ice causes the ponds to preferentially absorb solar radiation and therefore further affects surface ice melt. A physically based melt pond model was coupled to the thermodynamic-dynamic Louvain-la-Neuve Sea-Ice Model (LIM, version 3), which recently includes a representation of snow properties and processes. In the new snow scheme, snow is represented in multiple layers with varying thermo-physical properties, and simple parameterizations for blowing snow and fresh water refreezing into the snow were implemented. Several simulations were performed using the combined snow and melt pond configuration to study the impacts of the processes described above on the Arctic sea ice melt pond fractions. Preliminary results lead to two expected but uncorroborated model behaviors. In the simulations, blowing snow tends to decrease the average snow depth on sea ice due to losses into leads, thus allowing wider but shallower ponds on multiyear ice, while no significant effect is noticeable on first-year ice. Similarly, the refreezing of water in the snow curtails the amount of meltwater available to feed melt ponds on thick ice categories, where some snow may persist through the melt season, but has a limited or no impact on thin ice where snow melts away rapidly.

Lecomte, Olivier; Fichefet, Thierry; Flocco, Daniela; Schroeder, David; Vancoppenolle, Martin

2014-05-01

5

Microwave Signatures of Snow on Sea Ice: Modeling  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

6

Microwave Signatures of Snow on Sea Ice: Observations  

NASA Technical Reports Server (NTRS)

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.

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

7

Interdecadal changes in snow depth on Arctic sea ice  

NASA Astrophysics Data System (ADS)

plays a key role in the growth and decay of Arctic sea ice. In winter, it insulates sea ice from cold air temperatures, slowing sea ice growth. From spring to summer, the albedo of snow determines how much insolation is absorbed by the sea ice and underlying ocean, impacting ice melt processes. Knowledge of the contemporary snow depth distribution is essential for estimating sea ice thickness and volume, and for understanding and modeling sea ice thermodynamics in the changing Arctic. This study assesses spring snow depth distribution on Arctic sea ice using airborne radar observations from Operation IceBridge for 2009-2013. Data were validated using coordinated in situ measurements taken in March 2012 during the Bromine, Ozone, and Mercury Experiment (BROMEX) field campaign. We find a correlation of 0.59 and root-mean-square error of 5.8 cm between the airborne and in situ data. Using this relationship and IceBridge snow thickness products, we compared the recent results with data from the 1937, 1954-1991 Soviet drifting ice stations. The comparison shows thinning of the snowpack, from 35.1 ± 9.4 to 22.2 ± 1.9 cm in the western Arctic, and from 32.8 ± 9.4 to 14.5 ± 1.9 cm in the Beaufort and Chukchi seas. These changes suggest a snow depth decline of 37 ± 29% in the western Arctic and 56 ± 33% in the Beaufort and Chukchi seas. Thinning is negatively correlated with the delayed onset of sea ice freezeup during autumn.

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

2014-08-01

8

Properties of snow overlying the sea ice off East Antarctica in late winter, 2007  

Microsoft Academic Search

The properties of snow on East Antarctic sea ice off Wilkes Land were examined during the Sea Ice Physics and Ecosystem Experiment (SIPEX) in late winter of 2007, focusing on the interaction with sea ice. This observation includes 11 transect lines for the measurement of ice thickness, freeboard, and snow depth, 50 snow pits on 13 ice floes, and diurnal

Takenobu Toyota; Robert Massom; Kazutaka Tateyama; Takeshi Tamura; Alexander Fraser

2011-01-01

9

Airborne Surveys of Snow Depth over Arctic Sea Ice  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

10

Climate Records of Snow, Glaciers and Sea Ice  

NASA Astrophysics Data System (ADS)

Cryospheric data can be used to study global climate change. For example, various environmental factors contribute to changes in annual and interannual snow cover, glacier terminus movement and anomalies of sea ice extent. Archiving and making the data easily accessible is important. At the National Snow and Ice Data Center (NSIDC), three data sets in particular exhibit characteristics that allow for understanding global climate change. Users can analyze glacier retreat from historical glacier photographs, study changes in sea ice by reviewing historical ice charts, and review changes in the annual autumn snow cover onset and last day of snow cover in the Northern Hemisphere. By including a temporal component, the Timing and Statistics of Autumn and Spring Annual Snow Cover for the Northern Hemisphere data set is useful for analyzing statistics of snow cover timing and their relation to other environmental phenomena, for example, vegetation growth dynamics. The Online Glacier Photograph Database, which contains approximately 3,000 images, provides online search and order options for photographs that were previously in risk of deterioration. The Arctic Sea Ice Charts, 1953-1986: W. Dehn Collection data set includes ice charts of the Canadian and Alaskan Arctic Ocean that can be browsed by region and date range. Previously, these ice charts were archived in analog format and in need of long-term preservation. The NOAA Climate Database Modernization Program (CDMP) supported the digitization of both the historical photographs and the sea ice charts. By evaluating these data sets, users will have the opportunity to better interpret climatic change related to snow cover, sea ice and glacier retreat.

Ballagh, L.; Dye, D.; Howard, A.; Fetterer, F.

2005-12-01

11

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

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

12

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

NASA Technical Reports Server (NTRS)

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

Kurtz, Nathan T.; Farrell, Sinead L.

2011-01-01

13

The effect of snow on Antarctic sea ice simulations in a coupled atmosphere-sea ice model  

Microsoft Academic Search

The effect of a snow cover on sea ice accretion and ablation is estimated based on the ‘zero-layer’ version sea ice model\\u000a of Semtner, and is examined using a coupled atmosphere-sea ice model including feedbacks and ice dynamics effects. When snow\\u000a is disregarded in the coupled model the averaged Antarctic sea ice becomes thicker. When only half of the snowfall

X. Wu; W. F. Budd; V. I. Lytle; R. A. Massom

1999-01-01

14

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

NASA Astrophysics Data System (ADS)

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.

Hoppmann, M.; Nicolaus, M.

2011-12-01

15

Snow on Arctic sea ice: Updating the climatology and assessing its impact on ice ablation  

Microsoft Academic Search

The Arctic sea-ice cover is undergoing a major transformation with perennial ice extent decreasing at a rate of more than 8% per decade since 1979 and onset of seasonal ice formation delayed over much of the Arctic shelf seas. In this presentation we will (1) discuss the role of snow and its variability in summer surface ice melt, and (2)

H. Eicken; J. P. Harbeck; D. K. Perovich

2007-01-01

16

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

17

Contaminants in arctic snow collected over northwest Alaskan sea ice  

USGS Publications Warehouse

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

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

2002-01-01

18

Simulations of the snow covered sea ice surface temperature and microwave effective temperature  

Microsoft Academic Search

The snow surface on thick multiyear sea ice in winter is on average colder than the air because of the negative radiation balance. Beneath the snow surface there is a strong temperature gradient in winter with increasing temperatures towards the ice-water interface temperature at the freezing point around -1.8 °C. The sea ice surface temperature and the thermal microwave brightness

Rasmus T. Tonboe; Gorm Dybkjcr; Jacob L. Høyer

2011-01-01

19

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

20

Theoretical models for microwave remote sensing of snow-covered sea ice  

NASA Technical Reports Server (NTRS)

The volume scattering effects of snow-covered sea ice are studied with a three-layer random medium model for microwave remote sensing. Theoretical results are illustrated by matching experimental data for dry snow-covered thick first-year sea ice at Point Barrow. The radar backscattering cross sections are seen to increase with snow cover for snow-covered sea ice, due to the increased scattering effects in the snow layer. The results derived can also be applied to passive remote sensing.

Lin, F. C.; Kong, J. A.; Shin, R. T.

1987-01-01

21

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

NASA Technical Reports Server (NTRS)

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

Markus, T.; Cavalieri, D. J.

2006-01-01

22

Snow thickness retrieval over thick Arctic sea ice using SMOS satellite data  

NASA Astrophysics Data System (ADS)

The microwave interferometric radiometer of the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission measures at a frequency of 1.4 GHz in the L-band. In contrast to other microwave satellites, low frequency measurements in L-band have a large penetration depth in sea ice and thus contain information on the ice thickness. Previous ice thickness retrievals have neglected a snow layer on top of the ice. Here, we implement a snow layer in our emission model and investigate how snow influences L-band brightness temperatures and whether it is possible to retrieve snow thickness over thick Arctic sea ice from SMOS data. We find that the brightness temperatures above snow-covered sea ice are higher than above bare sea ice and that horizontal polarisation is more affected by the snow layer than vertical polarisation. In accordance with our theoretical investigations, the root mean square deviation between simulated and observed horizontally polarised brightness temperatures decreases from 20.0 K to 4.4 K, when we include the snow layer in the simulations. Under cold Arctic conditions we find brightness temperatures to increase with increasing snow thickness. Because dry snow is almost transparent in L-band, this brightness temperature's dependence on snow thickness origins from the thermal insulation of snow and its dependence on the snow layer thickness. This temperature effect allows us to retrieve snow thickness over thick sea ice. For the best simulation scenario and snow thicknesses up to 35 cm, the average snow thickness retrieved from horizontally polarised SMOS brightness temperatures agrees within 0.7 cm with the average snow thickness measured during the IceBridge flight campaign in the Arctic in spring 2012. The corresponding root mean square deviation is 6.3 cm, and the correlation coefficient is r2 = 0.55.

Maaß, N.; Kaleschke, L.; Tian-Kunze, X.; Drusch, M.

2013-07-01

23

Snow thickness retrieval over thick Arctic sea ice using SMOS satellite data  

NASA Astrophysics Data System (ADS)

The microwave interferometric radiometer of the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission measures at a frequency of 1.4 GHz in the L-band. In contrast to other microwave satellites, low frequency measurements in L-band have a large penetration depth in sea ice and thus contain information on the ice thickness. Previous ice thickness retrievals have neglected a snow layer on top of the ice. Here, we implement a snow layer in our emission model and investigate how snow influences L-band brightness temperatures and whether it is possible to retrieve snow thickness over thick Arctic sea ice from SMOS data. We find that the brightness temperatures above snow-covered sea ice are higher than above bare sea ice and that horizontal polarisation is more affected by the snow layer than vertical polarisation. In accordance with our theoretical investigations, the root mean square deviation between simulated and observed horizontally polarised brightness temperatures decreases from 20.9 K to 4.7 K, when we include the snow layer in the simulations. Although dry snow is almost transparent in L-band, we find brightness temperatures to increase with increasing snow thickness under cold Arctic conditions. The brightness temperatures' dependence on snow thickness can be explained by the thermal insulation of snow and its dependence on the snow layer thickness. This temperature effect allows us to retrieve snow thickness over thick sea ice. For the best simulation scenario and snow thicknesses up to 35 cm, the average snow thickness retrieved from horizontally polarised SMOS brightness temperatures agrees within 0.1 cm with the average snow thickness measured during the IceBridge flight campaign in the Arctic in spring 2012. The corresponding root mean square deviation is 5.5 cm, and the coefficient of determination is r2 = 0.58.

Maaß, N.; Kaleschke, L.; Tian-Kunze, X.; Drusch, M.

2013-12-01

24

Seasonal Variability of Snow Stratigraphy and Spectral Optical Properties on Sea Ice  

NASA Astrophysics Data System (ADS)

The optical properties of snow strongly influence the surface energy balance within the coupled atmosphere-ice- ocean system. They control the amount of solar short-wave radiation, reflected at the surface (surface albedo), scattered and absorbed within snow, and transmitted into the sea ice underneath. Snow stratigraphy and spectral transmission are crucial for biological studies on sea ice related communities and bio-chemical processes. Furthermore, the increasing importance of remote sensors for studying snow and sea ice in both Polar Regions raises the need of ground truth data of physical and. spectral optical snow and sea ice properties. We perform simultaneous spectral radiation and detailed snow stratigraphy measurements in various regions in the Arctic (Arctic Basin, Svalbard, Fram Strait) during different seasons. Time series of spectral albedo and transmission through snow and sea ice together with snow observations were gathered during drift stations and long term monitoring programs. These data sets give valuable information about the seasonal cycle of surface characteristics. For the optical measurements we are using high resolution ASD FieldSpec and TriOS Ramses radiometers. Snow studies are mainly based on systematic snow pit measurements of various properties, e.g. grain size, grain type, wetness, temperature complemented by photo documentary, thickness profiles, and physical properties of sea ice. Additionally, data analyses benefits from the application of the high resolution numerical snow model SNTHERM, which performs well in simulating snow properties on sea ice under various boundary conditions. Simulations are conducted for regions and times where in situ snow data are not available, and for performing detailed snow process studies.

Nicolaus, M.; Gerland, S.; Pedersen, C. A.

2007-12-01

25

Properties of snow overlying the sea ice off East Antarctica in late winter, 2007  

NASA Astrophysics Data System (ADS)

The properties of snow on East Antarctic sea ice off Wilkes Land were examined during the Sea Ice Physics and Ecosystem Experiment (SIPEX) in late winter of 2007, focusing on the interaction with sea ice. This observation includes 11 transect lines for the measurement of ice thickness, freeboard, and snow depth, 50 snow pits on 13 ice floes, and diurnal variation of surface heat flux on three ice floes. The detailed profiling of topography along the transects and the d 18O, salinity, and density datasets of snow made it possible to examine the snow-sea-ice interaction quantitatively for the first time in this area. In general, the snow displayed significant heterogeneity in types, thickness (mean: 0.14±0.13 m), and density (325±38 kg m -3), as reported in other East Antarctic regions. High salinity was confined to the lowest 0.1 m. Salinity and d 18O data within this layer revealed that saline water originated from the surface brine of sea ice in 20% of the total sites and from seawater in 80%. From the vertical profiles of snow density, bulk thermal conductivity of snow was estimated as 0.15 W K -1 m -1 on average, only half of the value used for numerical sea-ice models. Although the upward heat flux within snow estimated with this value was significantly lower than that within ice, it turned out that a higher value of thermal conductivity (0.3 to 0.4 W K -1 m -1) is preferable for estimating ice growth amount in current numerical models. Diurnal measurements showed that upward conductive heat flux within the snow and net long-wave radiation at the surface seem to play important roles in the formation of snow ice from slush. The detailed surface topography allowed us to compare the air-ice drag coefficients of ice and snow surfaces under neutral conditions, and to examine the possibility of the retrieval of ice thickness distribution from satellite remote sensing. It was found that overall snow cover works to enhance the surface roughness of sea ice rather than moderate it, and increases the drag coefficient by about 10%. As for thickness retrieval, mean ice thickness had a higher correlation with ice surface roughness than mean freeboard or surface elevation, which indicates the potential usefulness of satellite L-band SAR in estimating the ice thickness distribution in the seasonal sea-ice zone.

Toyota, Takenobu; Massom, Robert; Tateyama, Kazutaka; Tamura, Takeshi; Fraser, Alexander

2011-05-01

26

On the sensitivity of large scale sea-ice models to snow thermal conductivity  

NASA Astrophysics Data System (ADS)

In both hemispheres, the sea-ice snow cover is a key element in the local climate system and particularly in the processes driving the sea-ice thickness evolution. Because of its high reflectance and thermal insulating properties, the snow pack inhibits or delays the sea-ice summer surface melt. In winter however, snow acts as a blanket that curtails the heat loss from the sea ice to the atmosphere and therefore reduces the basal growth rate. Among the snow thermo-physical properties, snow thermal conductivity is known to be one of the most important with regard to the sea-ice-related thermodynamical processes. In the literature, both model and observational studies parameterize the snow thermal conductivity as a function of density and several different relationships are used. For the purpose of large scale modelling, one issue is then to have the snow density correctly represented while, for computational cost reasons, a comprehensive snow scheme can generally not be used in such models. Since it is known by observationalists that one of the key atmospheric parameters that affect snow thermal conductivity and density is the wind speed, one way to get around the problem is to try to have a realistic representation of the snow density profiles on the sea-ice directly using observations or simple wind speed depending parameterizations. In this study, we analyze the importance of the snow density profile and thermal conductivity in the thermodynamic-dynamic Louvain-la-Neuve Sea-Ice Model (LIM3), which is part of the ocean modelling platform NEMO (Nucleus for European Modelling of the Ocean, IPSL, Paris). In order to do this, a new snow thermodynamic scheme was developed and implemented into LIM3. This scheme is multilayer with varying snow thermo-physical properties. For memory and computational cost reasons, it includes only 3 layers but the vertical grid is refined in thermodynamic routines. Although snow density is time- and space-dependent in the model, it is not a prognostic variable. The shape of the density profile is either prescribed as a function of snow and ice thicknesses and based on snow pit observations, or parameterized as a function of seasonally averaged wind speeds. LIM3 exhibits a large sensitivity to the different tested formulations in both the Arctic, due to considerable changes in the sea-ice bottom growth and melting rates and therefore significant total sea-ice volume changes between the various runs ; and the Antarctic, because of strong ice-ocean feedbacks impacting on the sea-ice volume and extent of the whole Southern Ocean.

Lecomte, O.; Fichefet, T.; Vancoppenolle, M.; Massonnet, F.

2012-04-01

27

Melt Pond Development on Arctic Land-Fast Sea Ice in Relation to Snow and Ice Properties During the Ice Growth Season  

Microsoft Academic Search

The dynamics of melt pond development on sea ice were studied on a well-defined patch of level land-fast sea ice off the coast of Barrow, Alaska in 2008. The pond development was correlated with both sea ice properties and the history of snow distribution during the ice growth season. In mid January, the ice was covered by an almost level

C. Petrich; H. Eicken; D. Pringle; M. Sturm; D. Perovich; C. Polashenski; D. Finnegan

2008-01-01

28

Sea Ice SAR Signature Dependence on Thaw and Refreeze Event in the Snow Cover  

Microsoft Academic Search

As a result of the dependence of microwaves on the dielectric properties of the material they interfere with, the microwave signature of sea ice changes dramatically with the seasons as well as overnight when the snow layer is at the freezing point While pure ice and dry snow do not cause significant scattering and can be considered transparent throughout the

E. J. Hudier; S. Tolszczuk-Leclerc

2010-01-01

29

Arctic Ocean sea ice snow depth evaluation and bias sensitivity in CCSM  

NASA Astrophysics Data System (ADS)

Sea ice cover in the Arctic Ocean is a continued focus of attention. This study investigates the impact of the snow overlying the sea ice in the Arctic Ocean. The impact of snow depth biases in the Community Climate System Model (CCSM) is shown to impact not only the sea ice, but also the overall Arctic climate. Following the identification of seasonal biases produced in CCSM simulations, the thermodynamic transfer through the snow-ice column is perturbed to determine model sensitivity to these biases. This study concludes that perturbations on the order of the observed biases result in modification of the annual mean conductive flux through the snow-ice column of 0.5 W m2 relative to an unmodified simulation. The results suggest that the ice has a complex response to snow characteristics, with ice of different thicknesses producing distinct reactions. Our results indicate the importance of an accurate simulation of snow on the Arctic sea ice. Consequently, future work investigating the impact of current precipitation biases and missing snow processes, such as blowing snow, densification, and seasonal changes, is warranted.

Blazey, B. A.; Holland, M. M.; Hunke, E. C.

2013-12-01

30

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

31

On the representation of snow in large scale sea-ice models  

NASA Astrophysics Data System (ADS)

In both hemispheres, the sea-ice snow cover is a key element in the local climate system and particularly in the processes driving the sea-ice thickness evolution. Because of its high reflectance and thermal insulating properties, the snow pack inhibits or delays the sea-ice summer surface melt. In winter however, snow acts as a blanket that curtails the heat loss from the sea ice to the atmosphere and therefore reduces the basal growth rate. Among the processes controlling the snow state on sea ice, snowfall, wind and temperature changes are probably the most important. Despite its high horizontal heterogeneity, due to the transport by wind and the underlying sea-ice thickness distribution, the snow cover is vertically stratified. Each layer carries a signature of past weather events, for relatively recent snow, and metamorphic pathways that older snow may have been through. In a simplified model, this snow stratigraphy can be represented by its vertical density profi[|#12#|]le, while the other snow properties are assumed to be computationable from density. In this study, we analyze the importance of the snow density profi[|#12#|]le in both one-dimensional and full versions of the thermodynamic-dynamic Louvain-la-Neuve Sea-Ice Model (LIM3), which is part of the ocean modelling platform NEMO (Nucleus for European Modelling of the Ocean, IPSL, Paris). In order to do this, a new snow thermodynamic scheme was developed and implemented into LIM3. This scheme is multilayer with varying snow thermo-physical properties. For memory and computational cost reasons, it includes only 3 layers but the vertical grid is refi[|#12#|]ned in thermodynamic routines. Although snow density is time- and space-dependent in the model, it is not a prognostic variable. The shape of the density pro[|#12#|]file is prescribed as a function of snow and ice thicknesses, based on snow pit observations. Several typical profi[|#12#|]les are tested in the model and results are presented by comparison with the model's standard version and sea-ice extent satellite observations.

Lecomte, O.; Fichefet, T.; Vancoppenolle, M.; Massonnet, F.

2011-12-01

32

Elevated mercury measured in snow and frost flowers near Arctic sea ice leads  

Microsoft Academic Search

Elevated mercury concentrations have been reported in arctic coastal snow far from emission sources. The mercury is deposited during mercury depletion events (MDEs), a set of photochemical atmospheric reactions involving reactive halogens. The highest mercury concentrations are clustered near the coast, leading to speculation that sea ice or sea ice leads play a role in MDEs. The nature of this

T. A. Douglas; M. Sturm; W. R. Simpson; S. Brooks; S. E. Lindberg; D. K. Perovich

2005-01-01

33

Review of Electromagnetic Methods to Investigate Arctic and Antarctic Sea Ice and Snow  

NASA Astrophysics Data System (ADS)

During the last 5 years we have applied a variety of near-surface electric (ie, resistivity) and electromagnetic methods to investigate sea ice and snow on sea ice in the Antarctic and Arctic. Here we present field cases and lessons learned on the applicability for resolving distinct target parameters. The geophysical challenges of sea ice include its composition of (a) homogeneous, vertically anisotropic, one-dimensional (level) ice 0.5 to 4 m thick, and (b) highly heterogeneous, partly water impregnated three-dimensional pressure ridge features 2 to 10 m thick. Snow on sea ice is generally dry (until melt onset) and spans a thickness range of some centimetres up to a few meters. We applied several different types of equipment covering the frequency range from DC to radar for different tasks and targets. Ground Penetrating Radar (GPR) proved to be fast and portable for snow thickness profiling with the limitation of a minimum snow thickness around 10 cm. Electromagnetic induction (EMI) is a classic sea ice thickness profiling method used hand held on the ice, ship-borne suspended from outrigger-like constructions as well as airborne as helicopter towed sensors. Mostly regional ice plus snow thickness is derived from EMI measurements. Attempts have been made to retrieve internal ice properties such as porosity or age (conductivity) from EM soundings. DC-resistivity sounding clearly shows the vertical conductivity anisotropy of level sea ice, due to its crystalline structure and aging processes. Electrical Resistivity Tomography was conducted on Baltic and Arctic sea ice to determine the porosity of pressure ridge keels. Our results show the potentials and limitations of the different methods for climate related and engineering sea ice studies. geophysics.com/projects

Pfaffling, A.; Haas, C.; Meil{\\Ae}Nder-Larsen, M.; Bishop, J.; Flinspach, D.; Otto, D.; Reid, J. E.; Worby, A. P.

2007-12-01

34

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

35

Arctic Ocean sea ice snow depth evaluation and bias sensitivity in CCSM  

NASA Astrophysics Data System (ADS)

Sea ice cover in the Arctic Ocean is a continued focus of attention. This study assesses the capability of hindcast simulations of the Community Climate System Model (CCSM) to reproduce observed snow depths and densities overlying the Arctic Ocean sea ice. The model is evaluated using measurements provided by historic Russian polar drift stations. Following the identification of seasonal biases produced in the simulations, the thermodynamic transfer through the snow - ice column is perturbed to determine model sensitivity to these biases. This study concludes that perturbations on the order of the observed biases result in modification of the annual mean conductive flux of 0.5 W m-2 relative to an unmodified simulation. The results suggest that the ice has a complex response to snow characteristics, with ice of different thicknesses producing distinct reactions. Consequently, we suggest that the inclusion of additional snow evolution processes such as blowing snow, densification, and seasonal changes in snow conductivity in sea ice models would increase the fidelity of the model with respect to the physical system. Moreover, our results suggest that simulated high latitude precipitation biases have important effects on the simulated ice conditions, resulting in impacts on the Arctic climate in general in large-scale climate.

Blazey, B. A.; Holland, M. M.; Hunke, E. C.

2013-04-01

36

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

37

Sea ice and snow cover characteristics during the winter-spring transition in the Bellingshausen Sea: An overview of SIMBA 2007  

NASA Astrophysics Data System (ADS)

The Sea Ice Mass Balance in the Antarctic (SIMBA) experiment was conducted from the RVIB N.B. Palmer in September and October 2007 in the Bellingshausen Sea in an area recently experiencing considerable changes in both climate and sea ice cover. Snow and ice properties were observed at 3 short-term stations and a 27-day drift station (Ice Station Belgica, ISB) during the winter-spring transition. Repeat measurements were performed on sea ice and snow cover at 5 ISB sites, each having different physical characteristics, with mean ice (snow) thicknesses varying from 0.6 m (0.1 m) to 2.3 m (0.7 m). Ice cores retrieved every five days from 2 sites and measured for physical, biological, and chemical properties. Three ice mass-balance buoys (IMBs) provided continuous records of snow and ice thickness and temperature. Meteorological conditions changed from warm fronts with high winds and precipitation followed by cold and calm periods through four cycles during ISB. The snow cover regulated temperature flux and controlled the physical regime in which sea ice morphology changed. Level thin ice areas had little snow accumulation and experienced greater thermal fluctuations resulting in brine salinity and volume changes, and winter maximum thermodynamic growth of ˜0.6 m in this region. Flooding and snow-ice formation occurred during cold spells in ice and snow of intermediate thickness. In contrast, little snow-ice formed in flooded areas with thicker ice and snow cover, instead nearly isothermal, highly permeable ice persisted. In spring, short-lived cold air episodes did not effectively penetrate the sea ice nor overcome the effect of ocean heat flux, thus favoring net ice thinning from bottom melt over ice thickening from snow-ice growth, in all cases. These warm ice conditions were consistent with regional remote sensing observations of earlier ice breakup and a shorter sea ice season, more recently observed in the Bellingshausen Sea.

Lewis, M. J.; Tison, J. L.; Weissling, B.; Delille, B.; Ackley, S. F.; Brabant, F.; Xie, H.

2011-05-01

38

Snow depth and sea ice thickness from 2009 and 2010 IceBridge ATM data in the Weddell Sea and the Bellingshausen Seas in Antarctica  

NASA Astrophysics Data System (ADS)

IceBridge airborne measurements are intended to fill the gap in data on the elevations of the ice sheets and the sea ice covers, caused by the interval between the demise of ICESat 1's laser altimetry in 2009 and the launch of ICESat2 approximately in 2016. IceBridge LiDAR elevation measurements from aircraft are intended to provide a means of obtaining estimates of sea ice thickness and roughness with widespread application to sea ice modeling and effects of ongoing climate change. The IceBridge's Advanced Topographic Mapper (ATM) georeferenced L1B data provides elevations relative to a geoid at nominal spot size of 1-2m spaced at 5m intervals (at nadir) along track over a track swath width of 150m to 300m. Thus, in order to derive sea ice thickness and freeboard using the ATM L1B data, a local sea level reference must be established. The IceBridge's Digital Mapping System (DMS) is a digital camera that acquires high resolution natural color and panchromatic imagery from low and medium altitude. The DMS images are used to manually identify leads (open water or thin ice), where the ATM L1B elevations can be used as local sea level references. Then, the identified local sea level references are used to validate our algorithms to automatically determine the local sea level reference using the same ATM L1B data. Finally, we use the algorithm to determine the local sea level reference and thus derive the snow depth and sea ice thickness for all ATM L1B data over the Weddell Sea and the Bellingshausen-Amundsen Seas in two IceBridge missions to Antarctica in 2009 and 2010 based on an empirical relationship between snow depth and sea ice freeboard in this region.

Wang, X.; Xie, H.; Ackley, S. F.

2011-12-01

39

Sea Ice SAR Signature Dependence on Thaw and Refreeze Event in the Snow Cover  

NASA Astrophysics Data System (ADS)

As a result of the dependence of microwaves on the dielectric properties of the material they interfere with, the microwave signature of sea ice changes dramatically with the seasons as well as overnight when the snow layer is at the freezing point While pure ice and dry snow do not cause significant scattering and can be considered transparent throughout the winter season, the presence of liquid water, later on at spring, on air-ice or air-snow interfaces or within the snow cover turns the snow layer into an opaque medium and makes the air-snow interface the main contributor of the microwave backscattered to the SAR antenna. The availability of liquid water in the snow is the result of a shift in the thermodynamic balance of the snow layer and sea ice sheet. At spring, with the irradiance and air temperature increasing, the snow media quickly becomes isothermal. The snow layer is then a tri-phasic medium in which water changes state to balance radiations (short and long waves) and conductive heat fluxes variations. As a consequence, the surface layer of the snow cover is subject to a diurnal cycle of thaw during day time and refreeze at night which translates into a parallel diurnal cycle on snow wetness content. This cycle is of major relevance to microwave remote sensing applications and specifically to sea ice morphological features extraction. Using the output of a thermodynamic model of an isothermal snow cover forced by incoming L? and outgoing L? long-wave radiations, incident S? and reflected S? short-wave radiations and a turbulent atmospheric heat flux Qatm, an evaluation of the volume and surface components of a backscattered SAR is computed as a function of the SAR incident angle. We observe that when heat fluxes (irradiative and conductive) are positive, liquid water available in the top layer of the snow cover turns the air-snow interface into a specular reflector. Conversely, with wetness decreasing overnight, more energy can penetrate the snow medium, enhance the volume scattering contribution while turning the air-snow interface into an electromagnetically rough surface.

Hudier, E. J.; Tolszczuk-Leclerc, S.

2010-12-01

40

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

NASA Astrophysics Data System (ADS)

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.

Nemirovskaya, I. A.

2014-03-01

41

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

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

42

Applications of ISES for snow, ice, and sea state  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

43

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

NASA Astrophysics Data System (ADS)

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.

Nemirovskaya, I. A.

2014-05-01

44

The thickness distribution of sea ice and snow cover during late winter in the Bellingshausen and Amundsen Seas, Antarctica  

Microsoft Academic Search

Data collected from a voyage of RV Nathaniel B. Palmer to the Bellingshausen and Amundsen Seas during August-September 1993 are used to investigate the thickness distribution of sea ice and snow cover and the processes that influence the development of the first-year pack ice. The data are a combination of in situ and ship-based measurements and show that the process

A. P. Worby; M. O. Jeffries; K. Morris; R. Jaña

1996-01-01

45

Simulated effects of a snow layer on retrieval of CryoSat-2 sea ice freeboard  

NASA Astrophysics Data System (ADS)

impact of a snow layer on the location of the tracking point (RP) for ranging to the sea ice surface in CryoSat-2 synthetic aperture interferometric radar altimeter waveforms is simulated. With a range resolution of ~47 cm, the response of the air-snow (a-s) interface broadens the response of the snow-ice (s-i) interface and displaces the RP toward the altimeter. This effect is largest when the strengths of their returns are comparable and when snow thicknesses are >20 cm. On the other hand, the RP is displaced away from the altimeter when the reduced propagation speed in the snow layer is not accounted for. This analysis examines the dependence of these competing corrections on snow thickness and the relative scattering strengths of the interfaces and the sensitivity of two different tracking approaches (leading edge and centroid) to these snow parameters. Expected errors depend on a better understanding of the relative scattering strengths of the interfaces and snow layer.

Kwok, R.

2014-07-01

46

Brine-Wetted Snow on the Surface of Sea Ice: A Potentially Vast and Overlooked Microbial Habitat  

NASA Astrophysics Data System (ADS)

On the hemispheric scale, snow on the surface of sea ice significantly impacts the exchange of mass and energy across the ocean-ice-atmosphere interface. The snow cover over Arctic sea ice plays a central role in Arctic photochemistry, including atmospheric depletion events at the onset of spring, and in ecosystem support, by determining the availability of photosynthetically active radiation for algal primary production at the bottom of the ice. Among the non-uniformities of snow relevant to its larger-scale roles is salt content. When snow is deposited on the surface of new sea ice, brine expelled onto the ice surface during ice formation wicks into the snow by capillary action, forming a brine-wetted or saline snow layer at the ice-snow interface. A typical salinity for this basal snow layer in the Arctic (measured on a 3-cm depth interval of melted snow) is about 20 (ppt by optical salinometer), with maxima approaching 30 ppt, thus higher than the salinity of melted surface sea ice (< 12 ppt). Although the physical-chemical properties of this brine-wetted layer have been examined in recent years, and the (assumed) air-derived microbial content of overlying low-salinity snow is known to be low in winter, basal saline snow is essentially unexplored as a microbial habitat. As part of an NSF-supported project on frost flowers, we investigated snow overlying coastal sea ice off Barrow, Alaska, in February 2010 (since snow buries frost flowers). Sterile (ethanol-rinsed) tools were used to open snow pits 60 cm wide, record temperature by thermoprobe at 3-cm depth intervals, and collect samples from newly exposed snow walls for salinity (3-cm intervals) and biological measurements (6-cm intervals). The latter included counts of bacterial abundance by epifluorescence microscopy and assays of extracellular polysaccharide substances (EPS). We also sampled snow on a larger scale to extract sufficient DNA to analyze microbial community composition (ongoing work), as well as underlying sea ice for comparative purposes. Results indicated presence of an areally extensive saline snow layer (salinities of 18.5-30.9 ppt) that was enriched in bacteria (0.28-1.5 x 10E4 bacteria/ml) and EPS (0.07-0.22 mg glucose equivalents/L) relative to overlying low-salinity snow (0.3-9 ppt; 2-9 x 10E2 bacteria/ml; 0.021-0.11 mg glucose equivalents/L). Analysis of content and distribution of salts, bacteria and EPS throughout the snow and underlying sea ice indicated sea-ice brines as the source of these materials in snow. Although marine bacteria appeared to have moved upwards into snow in sync with brine, EPS was subject to different transport or production and degradation pathways, perhaps connected to a detected sensitivity of bacteria in upper sea ice brines to osmotic shock. The possible passive and dynamic roles of bacteria and their exudates in these brine-wetted snows in influencing the physical-chemical properties of snow over sea ice, including later season physical and biological impacts as the snow melts and infiltrates the ice below, await further study.

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

2010-12-01

47

Snow and Ice: The Sequel  

NSDL National Science Digital Library

In this lesson, learners use WebImage, a Web-based customized version of ImageJ, to investigate changes in snow cover and sea ice in the Northern Hemisphere over a period of 24 years. The images are obtained from satellite measurements of visible and microwave radiation. The lesson follows from Snow and Ice: A Hemispherical View.

48

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

49

Winter snow cover on the sea ice of the Arctic Ocean at the Surface Heat Budget of the Arctic Ocean (SHEBA)  

E-print Network

Winter snow cover on the sea ice of the Arctic Ocean at the Surface Heat Budget of the Arctic Ocean of the snow cover on the sea ice of the Arctic Ocean was observed during the Surface Heat Budget of the Arctic cover on the sea ice of the Arctic Ocean at the Surface Heat Budget of the Arctic Ocean (SHEBA

Sturm, Matthew

50

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

Microsoft Academic Search

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

Marcel Nicolaus; Christian Haas; Sascha Willmes

2009-01-01

51

On the Links between Microwave and Solar Wavelength Interactions with Snow-Covered First-Year Sea Ice  

Microsoft Academic Search

Electromagnetic (EM) energy at solar and microwavelengths will interact with a snow-covered sea ice volume as a function of its geophysical properties. The seasonal metamorphosis of the snow cover modulates the relative distribution of the three main interaction mechanisms of EM energy: reflection, transmission, and absorption. We use a combination of modeling and observational data to illustrate how the total

DAVID G. BARBER

1994-01-01

52

The effect of snow/sea ice type on the response of albedo and light penetration depth (e-folding depth) to increasing black carbon  

NASA Astrophysics Data System (ADS)

The optical properties of snow/sea ice vary with age and by the processes they were formed, giving characteristic types of snow and sea ice. The response of albedo and light penetration depth (e-folding depth) to increasing mass ratio of black carbon is shown to depend on the snow and sea ice type and the thickness of the snow or sea ice. The response of albedo and e-folding depth of three different types of snow (cold polar snow, wind-packed snow and melting snow) and three sea ice (multi-year ice, first-year ice and melting sea ice) to increasing mass ratio of black carbon is calculated using a coupled atmosphere-snow/sea ice radiative-transfer model (TUV-snow), over the optical wavelengths of 300-800 nm. The snow and sea ice types are effectively defined by a scattering cross-section, density and asymmetry parameter. The relative change in albedo and e-folding depth of each of the three snow and three sea ice types with increasing mass ratio of black carbon is considered relative to a base case of 1 ng g-1 of black carbon. The relative response of each snow and sea ice type is intercompared to examine how different types of snow and sea ice respond relative to each other. The relative change in albedo of a melting snowpack is a factor of four more responsive to additions of black carbon compared to cold polar snow over a black carbon increase from 1 to 50 ng g-1, while the relative change in albedo of a melting sea ice is a factor of two more responsive to additions of black carbon compared to multi-year ice for the same increase in mass ratio of black carbon. The response of e-folding depth is effectively not dependent on snow/sea ice type. The albedo of sea ice is more responsive to increasing mass ratios of black carbon than snow.

Marks, A. A.; King, M. D.

2014-09-01

53

National Snow and Ice Data Center (NSIDC)  

NSDL National Science Digital Library

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.

The National Snow and Ice Data Center (NSIDC)

54

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

55

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

Microsoft Academic Search

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.

Alan Robock

1980-01-01

56

Snow and Ice Data Discovery and Access  

NSDL National Science Digital Library

The National Snow and Ice Data Center has produced numerous resources for exploring snow and ice through data, images, and visualization. This site includes access to data sets, image banks, web-based map servers and Google Earth KML files. Topics include glaciers, sea ice, climate change, and polar research.

Center, National S.

57

National Snow and Ice Data Center  

NSDL National Science Digital Library

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.

Barry, Roger

2001-09-15

58

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

59

The Role of Snow Thickness over Arctic Winter Sea Ice in the Survival and Dispersal of Brine-Derived Microbes  

NASA Astrophysics Data System (ADS)

The brines of polar winter sea ice are inhabited by significant densities of microbes (Bacteria and Archaea) that experience a range of extreme conditions depending on location in, and age of, the ice. Newly formed sea ice in winter expels microbes (and organic exudates) onto the surface of the ice, where they can be wicked into frost flowers or into freshly deposited snow, resulting in populations at the ice-air and air-snow interfaces characterized by even more extreme conditions. The influence of snow thickness over the ice on the fate of these microbes, and their potential for dispersal or mediation of exchanges with other components of the ice-snow system, is not well known. Examination of in situ temperature data from the Mass Balance Observatory (MBO) offshore of Barrow, Alaska, during the winter of 2011 allowed recognition of an hierarchy of fluctuation regimes in temperature and (by calculation) brine salinity, where the most stable conditions were encountered within the sea ice and the least stable highest in the snow cover, where temperature fluctuations were significantly more energetic as determined by an analysis of power spectral density. A prior analysis of snow thickness near the MBO had already revealed significant ablation events, potentially associated with bacterial mortality, that would have exposed the saline (microbe-rich) snow layer to wind-based dispersal. To better understand the survival of marine bacteria under these dynamic and extreme conditions, we conducted laboratory experiments with Arctic bacterial isolates, subjecting them to simulations of the freezing regimes documented at the MBS. The impact of the fluctuation regime was shown to be species-specific, with the organism of narrower temperature and salinity growth ranges suffering 30-50% mortality (which could be partially relieved by providing protection against salt-shock). This isolate, the psychrophilic marine bacterium Colwellia psychrerythraea strain 34H (temperature range of -12 to 18°C, salinity range of 20 to 50), was originally isolated from Arctic marine sediments. The other isolate, the psychrotolerant and extremely halophilic bacterium Psychrobacter sp. strain 7E (temperature range of -1 [possibly lower] to 25°C, salinity range of 32 to 125), not only survived the most extreme conditions but demonstrated a potentially effective dispersal strategy of cell fragmentation and miniaturization (resulting in higher cell numbers). This extremophile was isolated from upper winter sea-ice brine in the Beaufort Sea. Bacterial survival and dispersal from sea-ice brines in Arctic winter thus appears to depend on the nature of the organisms involved and on the thickness of snow cover, which determines how dynamic and extreme are the exposure conditions. The observed species-specific reactions to extreme and fluctuating conditions may help to explain the different structures of microbial communities inhabiting the range of environments defined by the ice-snow system and provide model organisms and research directions for future work to evaluate potential activity or exchanges with other components of the system.

Deming, J. W.; Ewert, M.; Bowman, J. S.

2013-12-01

60

VOLUME 27, SPRING 2007 Ice,Snow and Glaciers  

E-print Network

VOLUME 27, SPRING 2007 Ice,Snow and Glaciers � What's Hot at CIRA in the International Polar, November 20, 2003. A penguin-shaped iceberg trapped in sea ice at Cape Hallett, Antarctica, in northern Changing Snow and Ice: IPY occurs amidst abundant evidence of changes in snow and ice: reductions in extent

Collett Jr., Jeffrey L.

61

Snow melt on sea ice surfaces as determined from passive microwave satellite data  

NASA Technical Reports Server (NTRS)

SMMR data for the year 1979, 1980 and 1984 have been analyzed to determine the variability in the onset of melt for the Arctic seasonal sea ice zone. The results show melt commencing in either the Kara/Barents Seas or Chukchi Sea and progressing zonally towards the central Asian coast (Laptev Sea). Individual regions had interannual variations in melt onset in the 10-20 day range. To determine whether daily changes occur in the sea ice surface melt, the SMMR 18 and 37 GHz brightness temperature data are analyzed at day/night/twilight periods. Brightness temperatures illustrate diurnal variations in most regions during melt. In the East Siberian Sea, however, daily variations are observed in 1979, throughout the analysis period, well before any melt would usually have commenced. Understanding microwave responses to changing surface conditions during melt will perhaps give additional information about energy budgets during the winter to summer transition of sea ice.

Anderson, Mark R.

1987-01-01

62

Methanesulfonic acid in coastal Antarctic snow related to sea-ice extent  

SciTech Connect

Proxy records of biogenic sulfur gas obtained from ice cores suggest that variability in marine biogenic sulfur emissions may reflect changes in climate. Increased sea-ice extent has previously been proposed as one cause of relatively high methanesulfonic acid (MSA) in glacial-age ice core samples. The authors have analyzed MSA, one of the oxidation products of the biogenic sulfur gas dimethylsulfide, from snowpit samples recovered from a coastal site in Southern Victoria Land, Antarctica. Time series of MSA correlate significantly with the longest continuous record available of Southern Ocean sea-ice extent (two decades).

Welch, K.A.; Mayewski, P.A.; Whitlow, S.I. (Univ. of New Hampshire, Durham (United States))

1993-03-19

63

Field Investigations of Ku-Band Radar Penetration Into Snow Cover on Antarctic Sea Ice  

Microsoft Academic Search

Monitoring long-term, large-scale changes in the Antarctic sea ice thickness is not currently possible due to the sampling constraints of the ship-based and airborne observations which comprise most of the available thickness data. Satellite radar altimetry has been used to measure sea ice thickness variability in the Arctic where it is assumed that the highest amplitude radar return originates from

Rosemary C. Willatt; Katharine A. Giles; Seymour W. Laxon; Lucas Stone-Drake; Anthony P. Worby

2010-01-01

64

2013 Arctic Sea Ice Minimum  

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 ...

65

Whither Arctic Sea Ice?  

NSDL National Science Digital Library

In this activity students work with real datasets to investigate a real situation regarding disappearing Arctic sea ice. The case study has students working side-by-side with a scientist from the National Snow and Ice Data Center and an Inuit community in Manitoba.

Youngman, Betsy; Chapter, Earth E.

66

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)

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.

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

1988-01-01

67

Observing the snow and ice properties in the Arctic coastal waters of the Canadian Beaufort Sea with helicopter-borne Ground-Penetrating Radar, Laser and Electromagnetic sensors  

NASA Astrophysics Data System (ADS)

A helicopter-borne Ground-Penetrating-Radar (GPR) has been providing in real-time snow depths and ice thicknesses of low saline ice and complemented the Electromagnetic-Laser and Video-Laser data sets to explain the winter and summer ice and snow properties found in the Canadian Beaufort Sea. In the shallow inshore delta areas where river runoff dilutes the oceanic water such as the Mackenzie Delta, the GPR and EM together can determine in winter the floating, grounded ice conditions from the ice frozen to the bottom where the EM on its own only indicates areas where the ice is attached to the frozen mud layer. In these low saline areas the GPR can measure both the snow depth and ice thickness and provide an estimate of the freshwater river plume layer trapped inshore behind the lad-fast shear zone. Overlain this survey data of 2010 on SAR imagery provides a means to validate the ice signature seen in satellite imagery. During the summer of 2009, the helicopter-borne sensors have observed the break-up of the Arctic pack ice by long period ocean surface waves generated in open water region north of the Bering Strait. The waves penetrating the Beaufort Sea pack ice up to 300km, breaking up the pack ice into less than 100m floes. All data and reports of the helicopter survey and publications are available http://www.mar.dfo-mpo.gc.ca/science/ocean/seaice/public.html and associated FTP site.

Prinsenberg, S.

2011-12-01

68

The Role of Snow and Ice in the Climate System  

SciTech Connect

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

Barry, Roger (NSIDC) [NSIDC

2007-12-19

69

Regional-scale sea-ice and snow thickness distributions from in situ and satellite measurements over East Antarctica during SIPEX 2007  

NASA Astrophysics Data System (ADS)

The Sea Ice Physics and Ecosystem eXperiment (SIPEX) was conducted in the East Antarctic pack ice zone between 115-130°E from 9 September - 11 October, 2007. In situ measurements of sea-ice and snow properties were conducted at 15 ice stations, together with ship-based ASPeCt observations. The ice and snow thickness varied considerably in different regions of the pack ice, with particularly thick ice associated with deformation and a strong slope jet in the southwest of the study region. The mean ice thickness was 0.99 m (1.57 m excluding the northern marginal ice zones), but varied from 0.61 m along the southern leg to 1.80 m along the western leg, with pockets of considerably thicker ice in some regions. Swell was observed on two occasions penetrating more than 330 km south of the ice edge into regions with 80-100% ice concentration. Ice thicknesses calculated from near coincident ICESat laser altimetry (1.74 m) are similar to the in-situ observations in the central pack (1.57 m).

Worby, Anthony P.; Steer, Adam; Lieser, Jan L.; Heil, Petra; Yi, Donghui; Markus, Thorsten; Allison, Ian; Massom, Robert A.; Galin, Natalia; Zwally, Jay

2011-05-01

70

Influence of snow cover and algae on the spectral dependence of transmitted irradiance through Arctic landfast first-year sea ice  

NASA Astrophysics Data System (ADS)

Extensive spatial and temporal observations of sea ice algae remain limited due in part to current destructive and time intensive sampling techniques. In this paper we examine the influence of snow cover and ice algal biomass on the spectral dependence of photosynthetically available radiation transmitted through the snow-ice matrix using a data set collected in Resolute Passage, Canada, from 3 to 21 May 2003. The relationships between a normalized difference index (NDI) of transmitted irradiance with ice algal biomass and with snow cover provided a means to examine and compare observational and modeled data. In contrast to the dominant scattering properties of snow, absorption largely controls the spectral diffuse attenuation coefficient of algae. Our results show that snow has little effect on the distribution of transmitted spectral irradiance at wavelengths between 400 and 550 nm, whereas algae have a strong absorption peak near 440 nm that dominates changes in spectral transmission across this wavelength range. Up to 89% of the total variation in algae biomass was accounted for with a single NDI wavelength combination. Therefore the blue wavelength peak in algal spectral absorption lends particularly well to the remote estimation of algae biomass using transmitted irradiance. Deviations between observed and modeled data highlight the need for improvements to model inputs and therefore more detailed observations of processes controlling snow, ice, and algae in situ optical properties.

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

2007-03-01

71

Sea Ice  

NASA Technical Reports Server (NTRS)

Sea ice covers vast areas of the polar oceans, with ice extent in the Northern Hemisphere ranging from approximately 7 x 10(exp 6) sq km in September to approximately 15 x 10(exp 6) sq km in March and ice extent in the Southern Hemisphere ranging from approximately 3 x 10(exp 6) sq km in February to approximately 18 x 10(exp 6) sq km in September. These ice covers have major impacts on the atmosphere, oceans, and ecosystems of the polar regions, and so as changes occur in them there are potential widespread consequences. Satellite data reveal considerable interannual variability in both polar sea ice covers, and many studies suggest possible connections between the ice and various oscillations within the climate system, such as the Arctic Oscillation, North Atlantic Oscillation, and Antarctic Oscillation, or Southern Annular Mode. Nonetheless, statistically significant long-term trends are also apparent, including overall trends of decreased ice coverage in the Arctic and increased ice coverage in the Antarctic from late 1978 through the end of 2003, with the Antarctic ice increases following marked decreases in the Antarctic ice during the 1970s. For a detailed picture of the seasonally varying ice cover at the start of the 21st century, this chapter includes ice concentration maps for each month of 2001 for both the Arctic and the Antarctic, as well as an overview of what the satellite record has revealed about the two polar ice covers from the 1970s through 2003.

Parkinson, Claire L.; Cavalieri, Donald J.

2005-01-01

72

Observations of geophysical and dielectric properties and ground penetrating radar signatures for discrimination of snow, sea ice and freshwater ice thickness  

Microsoft Academic Search

Separate snow and ice thickness at the same location are important parameters in determining the flux of heat and light between the atmosphere and ocean in Arctic marine environments, but physical sampling requires a great deal of effort to yield few results spatially and temporally. Here, ground penetrating radar (GPR) at 250 MHz and 1 GHz reliably measured snow, river ice and

R. J. Galley; M. Trachtenberg; A. Langlois; D. G. Barber; L. Shafai

2009-01-01

73

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  

Microsoft Academic Search

This paper presents the results of reconstructing the state of ice and snow covers on the Arctic Ocean from 1948 to 2002 obtained\\u000a with a couplod model of ocean circulation and sea-ice evolution. The area of the North Atlantic and Arctic Ocean north of\\u000a 65° N, excluding Hudson Bay, is considered. The monthly mean ice areas and extents are analyzed.

N. G. Yakovlev

2009-01-01

74

Search for Ice and Snow  

NSDL National Science Digital Library

Using an Earth image database (Space Shuttle images), students try to find places on Earth where there is ice and snow. In some arid areas, water can come from snow and ice found on nearby high mountains or at extreme latitudes. In this activity, students can express ideas about where there is ice on the Earth and why. They also can find Web images of Earth and download them to determine ways to distinguish areas of ice/snow from clouds or other white features on the images of Earth. In addition, students can use world maps to mark places where they find ice, putting in place names and/or coordinates where possible.

75

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

E-print Network

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

Royal Holloway, University of London

76

Snow and Ice Products from the Moderate Resolution Imaging Spectroradiometer  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

77

Snow Ice Crystals  

NSDL National Science Digital Library

This article from Physics Today by Yoshinori Furukawa and John S. Wettlaufer and John S. Wettlaufer describes how ice crystals form on the earth. The resource includes graphics depicting how different shapes of ice crystals are formed.

Furukawa, Y.; Wettlaufer, John S., 1963-

2010-03-12

78

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

PubMed

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

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

2014-01-01

79

Sea ice-albedo climate feedback mechanism  

Microsoft Academic Search

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,

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

1995-01-01

80

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

NASA Technical Reports Server (NTRS)

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

Cavalieri, D. J.

1988-01-01

81

Seasonality of halogen deposition in polar snow and ice  

NASA Astrophysics Data System (ADS)

The atmospheric chemistry of iodine and bromine in Polar regions is of interest due to the key role of halogens in many atmospheric processes, particularly tropospheric ozone destruction. Bromine is emitted from the open ocean but is enriched above first-year sea ice during springtime bromine explosion events, whereas iodine emission is attributed to biological communities in the open ocean and hosted by sea ice. It has been previously demonstrated that bromine and iodine are present in Antarctic ice over glacial-interglacial cycles. Here we investigate seasonal variability of bromine and iodine in polar snow and ice, to evaluate their emission, transport and deposition in Antarctica and the Arctic and better understand potential links to sea ice. We find that bromine and iodine concentrations and Br enrichment (relative to sea salt content) in polar ice do vary seasonally in Arctic snow and Antarctic ice. Although seasonal variability in halogen emission sources is recorded by satellite-based observations of tropospheric halogen concentrations, seasonal patterns observed in snowpack are likely also influenced by photolysis-driven processes. Peaks of bromine concentration and Br enrichment in Arctic snow and Antarctic ice occur in spring and summer, when sunlight is present. A secondary bromine peak, observed at the end of summer, is attributed to bromine deposition at the end of the polar day. Iodine concentrations are largest in winter Antarctic ice strata, contrary to contemporary observations of summer maxima in iodine emissions. These findings support previous observations of iodine peaks in winter snow strata attributed to the absence of sunlight-driven photolytic re-mobilisation of iodine from surface snow. Further investigation is required to confirm these proposed mechanisms explaining observations of halogens in polar snow and ice, and to evaluate the extent to which halogens may be applied as sea ice proxies.

Spolaor, A.; Vallelonga, P.; Gabrieli, J.; Martma, T.; Björkman, M. P.; Isaksson, E.; Cozzi, G.; Turetta, C.; Kjær, H. A.; Curran, M. A. J.; Moy, A. D.; Schönhardt, A.; Blechschmidt, A.-M.; Burrows, J. P.; Plane, J. M. C.; Barbante, C.

2014-09-01

82

Thermal conductivity and heat transfer through the snow on the ice of the Beaufort Sea  

E-print Network

measurements have been widely available for the Arctic Ocean [Vowinkel and Orvig, 1970; Radionov et al., 1997; Colony et al., 1998; Warren et al., 1999], but textural descriptions and thermal conductivity of the Beaufort Sea. These were made during project SHEBA (Surface HEat Budget of the Arctic Ocean) [Perovich et

Sturm, Matthew

83

National Snow and Ice Data Center  

NSDL National Science Digital Library

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.

National Snow and Ice Data Center (U.S)

1997-01-01

84

Sea ice-albedo climate feedback mechanism  

SciTech Connect

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.

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

85

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.

86

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.

87

Development of an autonomous sea ice tethered buoy for the study of ocean-atmosphere-sea ice-snow pack interactions: the O-buoy  

NASA Astrophysics Data System (ADS)

A buoy based instrument platform (the "O-buoy") was designed, constructed, and field tested for year-round measurement of ozone, bromine monoxide, carbon dioxide, and meteorological variables over Arctic sea ice. The O-buoy operated in an autonomous manner with daily, bi-directional data transmissions using Iridium satellite communication. The O-buoy was equipped with three power sources: primary lithium-ion battery packs, rechargeable lead acid packs, and solar panels that recharge the lead acid packs, and can fully power the O-buoy during summer operation. This system was designed to operate under the harsh conditions present in the Arctic, with minimal direct human interaction, to aid in our understanding of the atmospheric chemistry that occurs in this remote region of the world. The current design requires approximately yearly maintenance limited by the lifetime of the primary power supply. The O-buoy system was field tested in Elson Lagoon, Barrow, Alaska from February to May 2009, and deployed in the Beaufort Sea in October 2009. Here, we describe the design and present preliminary data.

Knepp, T. N.; Bottenheim, J.; Carlsen, M.; Carlson, D.; Donohoue, D.; Friederich, G.; Matrai, P. A.; Netcheva, S.; Perovich, D. K.; Santini, R.; Shepson, P. B.; Simpson, W.; Valentic, T.; Williams, C.; Wyss, P. J.

2010-02-01

88

Sea ice terminology  

SciTech Connect

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.

Not Available

1980-09-01

89

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

PubMed

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

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

2012-04-01

90

Development of an autonomous sea ice tethered buoy for the study of ocean-atmosphere-sea ice-snow pack interactions: the O-buoy  

NASA Astrophysics Data System (ADS)

A buoy based instrument platform (the "O-buoy") was designed, constructed, and field tested for year-round measurement of ozone, bromine monoxide, carbon dioxide, and meteorological variables over Arctic sea ice. The O-buoy operated in an autonomous manner with daily, bi-directional data transmissions using Iridium satellite communication. The O-buoy was equipped with three power sources: primary lithium-ion battery packs, rechargeable lead acid packs, and solar panels that recharge the lead acid packs, and can fully power the O-buoy during summer operation. This system was designed to operate under the harsh conditions present in the Arctic, with minimal direct human interaction, to aid in our understanding of the atmospheric chemistry that occurs in this remote region of the world. The current design requires approximately yearly maintenance limited by the lifetime of the primary power supply. The O-buoy system was field tested in Elson Lagoon, Barrow, Alaska from February to May 2009, and here we describe the design and present preliminary data.

Knepp, T. N.; Bottenheim, J.; Carlsen, M.; Carlson, D.; Donohoue, D.; Friederich, G.; Matrai, P. M.; Netcheva, S.; Perovich, D. K.; Santini, R.; Shepson, P. B.; Simpson, W.; Stehle, R.; Valentic, T.; Williams, C.; Wyss, P. J.

2009-09-01

91

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

Microsoft Academic Search

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

T. Fichefet; M. A. Morales Maqueda

1997-01-01

92

The interactive multisensor snow and ice mapping system  

Microsoft Academic Search

The interactive multisensor snow and ice mapping system (IMS) was developed to give snow and ice analysts the tools, on one platform, to inspect visually the imagery and mapped data from various sensor sources to determine the presence of snow and ice and to depict snow- and ice-covered areas on a map on a daily basis, in one hour or

Bruce H. Ramsay

1998-01-01

93

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)

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.

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

94

An enhancement of the NASA Team sea ice algorithm  

Microsoft Academic Search

An enhancement of the NASA Team sea ice concentration algorithm overcomes the problem of a low ice concentration bias associated with surface snow effects that are particularly apparent in Southern Ocean sea ice retrievals. The algorithm has the same functional form as the NASA Team algorithm, but uses a wider range of frequencies (19-85 GHz). It accommodates ice temperature variability

Thorsten Markus; Donald J. Cavalieri

2000-01-01

95

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)

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.

Yakovlev, N. G.

2009-08-01

96

Has Arctic Sea Ice Rapidly Thinned?  

Microsoft Academic Search

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

Greg Holloway; Tessa Sou

2002-01-01

97

Interferometric System for Measuring Thickness of Sea Ice  

NASA Technical Reports Server (NTRS)

The cryospheric advanced sensor (CAS) is a developmental airborne (and, potentially, spaceborne) radar-based instrumentation system for measuring and mapping the thickness of sea ice. A planned future version of the system would also provide data on the thickness of snow covering sea ice. Frequent measurements of the thickness of polar ocean sea ice and its snow cover on a synoptic scale are critical to understanding global climate change and ocean circulation.

Hussein, Ziad; Jordan, Rolando; McDonald, Kyle; Holt, Benjamin; Huang, John; Kugo, Yasuo; Ishimaru, Akira; Jaruwatanadilok, Semsak; Akins, Torry; Gogineni, Prasad

2006-01-01

98

Sea ice ecosystems.  

PubMed

Polar sea ice is one of the largest ecosystems on Earth. The liquid brine fraction of the ice matrix is home to a diverse array of organisms, ranging from tiny archaea to larger fish and invertebrates. These organisms can tolerate high brine salinity and low temperature but do best when conditions are milder. Thriving ice algal communities, generally dominated by diatoms, live at the ice/water interface and in recently flooded surface and interior layers, especially during spring, when temperatures begin to rise. Although protists dominate the sea ice biomass, heterotrophic bacteria are also abundant. The sea ice ecosystem provides food for a host of animals, with crustaceans being the most conspicuous. Uneaten organic matter from the ice sinks through the water column and feeds benthic ecosystems. As sea ice extent declines, ice algae likely contribute a shrinking fraction of the total amount of organic matter produced in polar waters. PMID:24015900

Arrigo, Kevin R

2014-01-01

99

Ice and Climate News, No. 9, June 2007 Snow and Ice on Kilimanjaro  

E-print Network

1 Ice and Climate News, No. 9, June 2007 Snow and Ice on Kilimanjaro Douglas R. Hardy (dhardy snow and ice, appearing to float 5,000 m above the plains, has helped make Kilimanjaro one of the most of snow and ice on the mountain, rekin- dling controversy over snow, ice, and climate on Kilimanjaro which

Massachusetts at Amherst, University of

100

Is sea salt in ice cores a proxy of past sea ice extent?  

NASA Astrophysics Data System (ADS)

A number of marine, coastal and ice core proxies have been used to try to assess the past extent of sea ice. Sea salt has been proposed as a proxy for past ice extent, at least in the Southern Ocean. The idea is that the sea ice surface itself holds a source of sea salt, that is stronger than the source from the open ocean it replaces. That a sea ice source exists is apparent from observations of the ratio of sulphate to sodium in coastal aerosol and snow samples. While the idea behind using sea salt as a proxy is attractive, and leads to sensible inferences, many doubts remain. Firstly the exact nature of the source remains uncertain, and secondly it is not clear if ice extent, as opposed to changes in atmospheric transport and lifetime, would dominate variability in the ice core record of sea salt. Here we use a model of atmospheric transport and chemistry (p-TOMCAT) to assess the consequences of a sea ice source, focussing particularly on a source that has been proposed to arise from the sublimation of salty blowing snow. We will briefly report some new observations from a winter cruise, that will allow us to comment on the likelihood that blowing snow does pose a significant source. We will then present results from the model (implemented using existing parameters). The model has been run with seasonally and interannually varying sea ice extent and meteorology for the Antarctic, tracking, at different ice core sites, the concentration that arises from the open ocean and sea ice sources. We have already shown that the model, after tuning, is able to reproduce the magnitude and seasonal cycle of sea salt at a range of sites globally. By varying each component separately we explore which factors (sea ice presence, wind speed at source, transporting winds) and which source regions control the delivery of sea salt to sites in Antarctica. Such work suggests that sea salt cannot be used as a sea ice proxy on interannual timescales, but may be suitable on longer timescales. By employing much larger sea ice extents, such as at the last glacial maximum (LGM), we find a strong increase in concentration at ice core sites when ice extent increases. The increase in modelled sea salt concentration tails off sharply as ice approaches the LGM extent, so that the sensitivity of the proxy is greater at lower ice extents, for example in interglacials. We will discuss the implications of this work for the proposed use of sea salt as a sea ice proxy.

Levine, James; Wolff, Eric; Frey, Markus; Jenkins, Hazel; Jones, Anna; Yang, Xin

2014-05-01

101

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

E-print Network

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

Feltham, Daniel

102

Bacterial diversity in snow on North Pole ice floes.  

PubMed

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

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

103

Sea ice in the China Sea  

SciTech Connect

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.

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

1993-12-31

104

Impact of snow cover on CO2 dynamics in Antarctic pack ice  

NASA Astrophysics Data System (ADS)

Temporal evolution of pCO2 profiles in sea ice in the Bellingshausen Sea, Antarctica, in October 2007 shows that the CO2 system in the ice was primarily controlled by physical and thermodynamic processes. During the survey, a succession of warming and cold events 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 confirm 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 muted these changes, suggesting that snow influences changes in the sea ice carbonate system through its impact on the temperature and salinity of the sea ice cover. During this survey, pCO2 was undersaturated with respect to the atmosphere both in situ, in the bulk ice (from 10 to 193 ?atm), and in the brine (from 65 to 293 ?atm), and the ice acted as a sink for atmospheric CO2 (up to 2.9 mmol m-2 d-1), despite the underlying supersaturated seawater (up to 462 ?atm).

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

2014-06-01

105

Impacts of Declining Arctic Sea Ice: An International Challenge  

Microsoft Academic Search

As reported by the National Snow and Ice Data Center in late August of 2008, Arctic sea ice extent had already fallen to its second lowest level since regular monitoring began by satellite. As of this writing, we were closing in on the record minimum set in September of 2007. Summers may be free of sea ice by the year

M. Serreze

2008-01-01

106

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

NASA Technical Reports Server (NTRS)

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

Hall, Dorothy K. (Editor)

1995-01-01

107

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

NASA Technical Reports Server (NTRS)

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

Rango, A.

1979-01-01

108

Enhanced Sea Ice Concentration and Ice Temperature Algorithms for AMSR  

NASA Technical Reports Server (NTRS)

Accurate quantification of sea ice concentration and ice temperature from satellite passive microwave data is important because they provide the only long term, spatially detailed and consistent data set needed to study the climatology of the polar regions. Sea ice concentration data are used to derive large-scale daily ice extents that are utilized in trend analysis of the global sea ice cover. They are also used to quantify the amount of open water and thin ice in polynya and divergence regions which together with ice temperatures are in turn needed to estimate vertical heat and salinity fluxes in these regions. Sea ice concentrations have been derived from the NASA Team and Bootstrap algorithms while a separate technique for deriving ice temperature has been reported. An integrated technique that will utilizes most of the channels of AMSR (Advanced Microwave Scanning Radiometer) has been developed. The technique uses data from the 6 GHz and 37 GHz channels at vertical polarization obtain an initial estimate of sea ice concentration and ice temperature. The derived ice temperature is then utilized to estimate the emissivities for the corresponding observations at all the other channels. A procedure for calculating the ice concentration similar to the Bootstrap technique is then used but with variables being emissivities instead of brightness temperatures to minimizes errors associated with spatial changes in ice temperatures within the ice pack. Comparative studies of ice concentration results with those from other algorithms, including the original Bootstrap algorithm and those from high resolution satellite visible and infrared data will be presented. Also, results from a simulation study that demonstrates the effectiveness of the technique in correcting for spatial variations in ice temperatures will be shown. The ice temperature results are likewise compared with satellite infrared and buoy data with the latter adjusted to account for the effects of the snow cover.

Comiso, Josefino C.; Manning, Will; Gersten, Robert

1998-01-01

109

Sea-ice thickness and mass at Ice Station Belgica, Bellingshausen Sea, Antarctica  

NASA Astrophysics Data System (ADS)

Ice Station Belgica was commenced in late winter 2007 in the Bellingshausen Sea as part of Sea Ice Mass Balance in Antarctica (SIMBA), an IPY 2007 cruise on the research vessel N.B. Palmer. A primary objective was to build on the work of previous Antarctic drift station experiments to geophysically characterize sea ice in terms of thickness, surface and ice bottom morphology, and ultimately area-unitized mass. A 24 day drift station was established at approximately 70°S and 93°W in mixed first-year and multi-year ice with three geophysical study sites selected on a 5 km 2 floe. A comprehensive time series assessment of elevation-surveyed transects ranging from 100 m to 300 m in length included snow surface elevation, snow depth, electromagnetic (EM) profiling, and direct drilling for ice draft and ice freeboard. Additional work included a snow surface morphology characterization of a 100 m×300 m area between the primary time series EM transects. Correlation of EM ice thicknesses with collocated drilled ice thickness yielded equations for the correction of EM underestimation of thick deformed ice, particularly at pressure ridges. Mean ice thickness from corrected EM was compared to isostatic ice thickness calculated from surface elevation, snow depth, ice freeboard and respective snow, slush, ice, and sea water densities. Results were consistent, with mean ice thicknesses for multi-year ice of 2.35 m, 2.34 m, and 2.41 m, with similar variance, for corrected EM, drilling, and buoyancy methods respectively. Additionally, a mean ice thickness of 2.31 m was calculated from ASPeCt observations of the ice field associated with the floe, using the method incorporating mean sail heights and fractional coverage of surface deformities or ridging. Temporal series assessment of ice freeboard indicated a slightly negative mean ice freeboard (<0.04 m), with clear evidence of new snow-ice formation from the freezing of slush. The three distinct snow and ice regions assessed on the Belgica floe had mean corrected EM ice thickness of 0.52±0.04 m (±1 std. deviation), 0.92±0.17 m, and 2.35±1.37 m, and mean snow depths of 0.08±0.03 m, 0.36±0.09 m, and 0.68±0.31 m respectively. Each ice type represented a sizable fraction of the floe's total area (˜20%, 40%, and 40% respectively from visual estimates) reflecting a complex dynamic and thermodynamic history of formation, as well as the difficulty in characterizing even a single floe by a single class or mean value for thickness and snow depth. Implications of these results are discussed with regards to the resolution of satellite-based altimetry and snow depth products and efforts to generate and validate satellite sea ice and snow thickness products.

Weissling, B. P.; Lewis, M. J.; Ackley, S. F.

2011-05-01

110

Monitoring Snow on ice as Critical Habitat for Ringed Seals  

NASA Astrophysics Data System (ADS)

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.

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

2007-12-01

111

Water, Ice, and Snow: Unit Outlines  

NSDL National Science Digital Library

This article assembles free resources from the Water, Ice, and Snow issue of the Beyond Penguins and Polar Bears cyberzine into a unit outline based on the 5E learning cycle framework. Outlines are provided for Grades K-2 and 3-5.

Fries-Gaither, Jessica

112

Snow and Ice: A Hemispherical View  

NSDL National Science Digital Library

In this lesson, learners compare snow and ice cover in the Northern Hemisphere over a period of two years. The images are obtained from measurements of visible and microwave radiation taken by satellites and sent back to Earth and are analyzed with a customized version of ImageJ running as an applet within a browser.

113

Diatom vertical migration within land-fast Arctic sea ice  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

114

Soot climate forcing via snow and ice albedos  

NASA Astrophysics Data System (ADS)

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

Hansen, James; Nazarenko, Larissa

2004-01-01

115

Forthcoming Northern Hemisphere Snow and Ice Earth System Data Records  

NASA Astrophysics Data System (ADS)

For approximately the past five years, a multi-institutional team has been assembling satellite-derived Northern Hemisphere (NH) snow cover Earth System Data Records (ESDR). With the culmination of our NASA-supported Making Earth Science Data Records for Use in Research Environments (MEaSUREs) project come mid 2014, it is timely to bring the user community that encompasses the research community, decision-makers, and stakeholders up to date on our progress and with products soon to be available. Datasets include snow extent and melt state over NH continents, snowmelt state over Greenland, snowmelt onset and age of sea ice. Fused snow extent and melt state products over land and ice are also being generated. Visible and microwave satellite data are employed in these efforts. Datasets of both individual and integrated ESDRs will be available for downloading from the National Snow and Ice Data Center. Products are being generated at 25 km (1999-2010) or 100 km (1967-2010) resolution using the Equal-Area Scalable Earth Grid 2.0 and are available in netCDF format. Extensive metadata will accompany the datasets. Project data and information are also available at http://snowcover.org. Here, we will present examples of the development and utility of these individual and fused datasets.

Robinson, D. A.; Estilow, T. W.; Anderson, M. R.; Hall, D. K.; Henderson, G. R.; Mote, T. L.; Tschudi, M. A.

2013-12-01

116

Sea ice in the Baltic Sea A review  

NASA Astrophysics Data System (ADS)

Although the seasonal ice cover of the Baltic Sea has many similarities to its oceanic counterpart in Polar Seas and Oceans, there are many unique characteristics that mainly result from the brackish waters from which the ice is formed, resulting in low bulk salinities and porosities. In addition, due to the milder climate than Polar regions, the annual maximum ice extent is highly variable, and rain and freeze-melt cycles can occur throughout winter. Up to 35% of the sea ice mass can be composed from metamorphic snow, rather than frozen seawater, and in places snow and superimposed ice can make up to 50% of the total ice thickness. There is pronounced atmospheric deposition of inorganic nutrients and heavy metals onto the ice, and in the Bothnian Bay it is estimated that 5% of the total annual flux of nitrogen and phosphorus and 20-40% of lead and cadmium may be deposited onto the ice fields from the atmosphere. It is yet unclear whether or not the ice is simply a passive store for atmospherically deposited compounds, or if they are transformed through photochemical processes or biological accumulation before released at ice and snow melt. As in Polar sea ice, the Baltic ice can harbour rich biological assemblages, both within the ice itself, and on the peripheries of the ice at the ice/water interface. Much progress has been made in recent years to study the composition of these assemblages as well as measuring biogeochemical processes within the ice related to those in underlying waters. The high dissolved organic matter loading of Baltic waters and ice result in the ice having quite different chemical characteristics than those known from Polar Oceans. The high dissolved organic material load is also responsible in large degree to shape the optical properties of Baltic Sea ice, with high absorption of solar radiation at shorter wavelengths, a prerequisite for active photochemistry of dissolved organic matter. Land-fast ice in the Baltic also greatly alters the mixing characteristics of river waters flowing into coastal waters. River plumes extend under the ice to a much greater distance, and with greater stability than in ice-free conditions. Under-ice plumes not only alter the mixing properties of the waters, but also result in changed ice growth dynamics, and ice biological assemblages, with the underside of the ice being encased, in the extreme case, with a frozen freshwater layer. There is a pronounced gradient in ice types from more saline ice in the south to freshwater ice in the north. The former is characteristically more porous and supports more ice-associated biology than the latter. Ice conditions also vary considerably in different parts of the Baltic Sea, with ice persisting for over half a year in the northernmost part of the Baltic Sea, the Bothnian Bay. In the southern Baltic Sea, ice appears only during severe winters.

Granskog, Mats; Kaartokallio, Hermanni; Kuosa, Harri; Thomas, David N.; Vainio, Jouni

2006-10-01

117

Record Sea Ice Minimum  

NASA Technical Reports Server (NTRS)

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

2007-01-01

118

2011 Sea Ice Minimum  

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) ...

119

HAS ARCTIC SEA ICE RAPIDLY THINNED?  

Microsoft Academic Search

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.

Greg Holloway; Tessa Sou

2001-01-01

120

Albedo of the ice covered Weddell and Bellingshausen Seas  

NASA Astrophysics Data System (ADS)

This study investigates the surface albedo of the sea ice areas adjacent to the Antarctic Peninsula during the austral summer. Aircraft measurements of the surface albedo, which were conducted in the sea ice areas of the Weddell and Bellingshausen Seas show significant differences between these two regions. The averaged surface albedo varied between 0.13 and 0.81. The ice cover of the Bellingshausen Sea consisted mainly of first year ice and the sea surface showed an averaged sea ice albedo of ?i = 0.64 ± 0.2 (± standard deviation). The mean sea ice albedo of the pack ice area in the western Weddell Sea was ?i = 0.75 ± 0.05. In the southern Weddell Sea, where new, young sea ice prevailed, a mean albedo value of ?i = 0.38 ± 0.08 was observed. Relatively warm open water and thin, newly formed ice had the lowest albedo values, whereas relatively cold and snow covered pack ice had the highest albedo values. All sea ice areas consisted of a mixture of a large range of different sea ice types. An investigation of commonly used parameterizations of albedo as a function of surface temperature in the Weddell and Bellingshausen Sea ice areas showed that the albedo parameterizations do not work well for areas with new, young ice.

Weiss, A. I.; King, J. C.; Lachlan-Cope, T. A.; Ladkin, R. S.

2012-04-01

121

Soot climate forcing via snow and ice albedos  

PubMed Central

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

Hansen, James; Nazarenko, Larissa

2004-01-01

122

Physical processes determining the Antarctic sea ice environment  

Microsoft Academic Search

The Antarctic sea ice zone undergoes one of the greatest seasonal surface changes on Earth, with an annual change in extent of around 15£10 6 km 2 . This ice, and its associated snow cover, plays a number of important roles in the ocean{atmosphere climate system: the high albedo ice cover restricts surface absorption of solar radiation and acts as

Ian Allison; Antarctic CRC

1997-01-01

123

Physica B 338 (2003) 274283 Critical behavior of transport in sea ice  

E-print Network

Physica B 338 (2003) 274­283 Critical behavior of transport in sea ice K.M. Golden* Department materials such as sea ice, rocks, soils, snow, and glacial ice are composite media with complex, random significant large-scale geophysical effects. For example, sea ice, which mediates energy transfer between

Golden, Kenneth M.

124

Arctic Sea Ice  

NSDL National Science Digital Library

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.

Meier, Beverly L.

2012-06-26

125

Sea ice microbial communities (SIMCO)  

Microsoft Academic Search

Sea ice microbial communities (SIMCO) grow luxuriantly within several microhabitats of sea ice, indicating that the microorganisms comprising these communities are well adapted to the physicochemical gradients which characterize sea ice. We used SIMCO obtained from the bottom of congelation ice in McMurdo Sound, Antarctica, to test the hypothesis that low temperature limits microbial productivity in polar oceans and also

Steven T. Kottmeier; Cornelius W. Sullivan

1988-01-01

126

Snow and Ice Field Handbook for Snowplow Operators  

E-print Network

Minnesota Snow and Ice Control Field Handbook for Snowplow Operators Second Revision Manual Number Local Road Research Board #12;#12;Minnesota Snow and Ice Control Field Handbook for Snowplow Operators for an Effective Anti-icing Program, produced by the Utah LTAP Center. Thanks to the following sponsors

Minnesota, University of

127

Sea-ice Environmental Research Facility  

NASA Astrophysics Data System (ADS)

The Sea-ice Environmental Research Facility (SERF) is the first experimental sea-ice facility in Canada. Located in Winnipeg on the campus of the University of Manitoba, the main feature of SERF is an outdoor seawater pool (60 feet long, 30 feet wide and 8 feet deep) with a movable roof, numerous in situ sensors and instruments, and an on site trailer laboratory. Sea ice can be created at the pool under various controlled conditions (e.g., seawater chemistry, snow cover, heating) with the additions of chemical, isotopic and/or microbiological tracers. During the 2011-2012 inaugural year of operation, several types of sea ice including pancake ice and frost flowers were successfully created at the SERF pool. Real-time monitoring was carried out on surface and optical properties and on the evolution of temperature, salinity, dissolved oxygen, pH, alkalinity, pCO2, and mercury in and across the sea ice environment. The results demonstrate that SERF could provide a unique research platform for hypothesis-driven, mesocosm-scale studies to examine geophysical properties and biogeochemical processes in the sea ice environment.

Rysaard, S.; Wang, F.; Papakyriakou, T. N.; Barber, D. G.

2012-12-01

128

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

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

129

Seafloor Control on Sea Ice  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

130

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

Microsoft Academic Search

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

K. Rikiishi

2008-01-01

131

Albedo of the ice-covered Weddell and Bellingshausen Sea  

NASA Astrophysics Data System (ADS)

This study investigates the surface albedo of the sea ice areas adjacent to the Antarctic Peninsula during the austral summer. Aircraft measurements of the surface albedo which were conducted in the sea ice areas of the Weddell and Bellingshausen Sea show significant differences between these two regions. The averaged surface albedo varied between 0.13 and 0.81. The ice cover of the Bellingshausen Sea consisted mainly of first year ice and the sea surface showed an averaged sea ice albedo of ?i = 0.64 ± 0.2 (± standard deviation). The mean sea ice albedo of the pack ice area in the Western Weddell Sea was ?i = 0.75 ± 0.05. In the Southern Weddell Sea, where new, young sea ice prevailed, a mean albedo value of ?i = 0.38 ± 0.08 was observed. Relatively warm open water and thin, newly formed ice had the lowest albedo values, whereas relatively cold and snow-covered pack ice had the highest albedo values. All sea ice areas consist of a mixture of a large variability of different sea ice types. An investigation of commonly used parameterizations of albedo as a function of surface temperature in the Weddell and Bellingshausen Sea ice areas showed that the albedo parameterizations don't work well in particular for areas with new, young ice. We determined typical linear temperature-albedo functions for three sea ice areas adjacent to the Antarctic Peninsula, which are reflecting the differences in the mixture of ice age, thickness and sea ice surface cover.

Weiss, A. I.; King, J. C.; Lachlan-Cope, T. A.; Ladkin, R. S.

2011-11-01

132

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

133

Antarctic Sea Ice Thickness From Surface Elevation: A Multi-Sensor Approach  

NASA Astrophysics Data System (ADS)

Sea ice is an important component of the climate system affecting ocean-atmospheric interactions and global energy balance. The assessment of sea ice thickness using satellite and airborne laser altimetry is largely dependent upon isostatic buoyancy relationships between snow, ice, slush and ocean water. The use of these relationships in estimating sea ice thickness is complicated by a number of factors including spatial resolution, changing sea level reference, varying snow and ice density, and snow-ice interface flooding. Previous work has suggested that the effects of these factors can be reduced using a multi-sensor approach. The X-band backscatter from TerraSAR-X (TSX) is sensitive to surface roughness, snow and ice properties, and the presence of wet snow. The combined use of TSX for sea ice characterization and laser altimetry has the potential to provide more accurate estimates of sea ice thickness. In this study, we examine the feasibility of using TSX dual-polarized backscatter data to determine ice characteristics in the Bellingshausen and Amundsen Sea in the Antarctic region. Actual surface sea ice characteristics were derived from sea ice station measurements during the J.C. Ross (ICEBell) and Oden Southern Ocean (OSO) expeditions during the austral summer of 2010-11. Data from ice mass-balance buoys emplaced during the two cruises continued through summer melt and bridged the transition into fall freeze up conditions in the snow pack and ice cover. Shannon entropy derived from TSX, measures the statistical disorder of a medium illuminated by the radar, being a sum of two contributions related to intensity and the degree of polarization. A geostatistical approach is employed to correlate measured surface properties and sea ice freeboard with TSX-derived Shannon entropy. The floes are subsequently classified based on Shannon entropy and used in an empirically-based buoyancy model to estimate sea ice thickness. This approach is then compared with estimates based on isostasy with assumed values of snow and ice density.

Necsoiu, M.; Lewis, M. J.; Parra, J.; Ackley, S. F.; Weissling, B.; Hwang, B.

2011-12-01

134

Sea-ice thickness distribution of the Bellingshausen Sea from surface measurements and ICESat altimetry  

NASA Astrophysics Data System (ADS)

Although sea-ice extent in the Bellingshausen-Amundsen (BA) seas sector of the Antarctic has shown significant decline over several decades, there is not enough data to draw any conclusion on sea-ice thickness and its change for the BA sector, or for the entire Southern Ocean. This paper presents our results of snow and ice thickness distributions from the SIMBA 2007 experiment in the Bellingshausen Sea, using four different methods (ASPeCt ship observations, downward-looking camera imaging, ship-based electromagnetic induction (EM) sounding, and in situ measurements using ice drills). A snow freeboard and ice thickness model generated from in situ measurements was then applied to contemporaneous ICESat (satellite laser altimetry) measured freeboard to derive ice thickness at the ICESat footprint scale. Errors from in situ measurements and from ICESat freeboard estimations were incorporated into the model, so a thorough evaluation of the model and uncertainty of the ice thickness estimation from ICESat are possible. Our results indicate that ICESat derived snow freeboard and ice thickness distributions (asymmetrical unimodal tailing to right) for first-year ice (0.29±0.14 m for mean snow freeboard and 1.06±0.40 m for mean ice thickness), multi-year ice (0.48±0.26 and 1.59±0.75 m, respectively), and all ice together (0.42±0.24 and 1.38±0.70 m, respectively) for the study area seem reasonable compared with those values from the in situ measurements, ASPeCt observations, and EM measurements. The EM measurements can act as an appropriate supplement for ASPeCt observations taken hourly from the ship's bridge and provide reasonable ice and snow distributions under homogeneous ice conditions. Our proposed approaches: (1) of using empirical equations relating snow freeboard to ice thickness based on in situ measurements and (2) of using isostatic equations that replace snow depth with snow freeboard (or empirical equations that convert freeboard to snow depth), are efficient and important ways to derive ice thickness from ICESat altimetry at the footprint scale for Antarctic sea ice. Spatial and temporal snow and ice thickness from satellite altimetry for the BA sector and for the entire Southern Ocean is therefore possible.

Xie, H.; Ackley, S. F.; Yi, D.; Zwally, H. J.; Wagner, P.; Weissling, B.; Lewis, M.; Ye, K.

2011-05-01

135

Sea ice radiative forcing, sea ice area, and climate sensitivity  

NASA Astrophysics Data System (ADS)

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

Caldeira, Ken; Cvijanovic, Ivana

2014-05-01

136

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

E-print Network

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

Criscitiello, Alison Sara

2014-01-01

137

Applied Sea Ice Research  

NASA Astrophysics Data System (ADS)

In the late 1960s oil and gas development became an issue in the northern coastal areas of Alaska and Canada. More lately this has also become an issue in the Euroasian Arctic with the Barents and Kara Seas as example on where offshore hydrocarbon production now is being planned. In such waters the key questions prior to a development are related to water depths at the site and in case of ice, how frequent and what type of ice features will be met. Especially the ice conditions and knowledge about them are very decisive for the field development solutions to be chosen. The paper will highlight examples on development solutions where the ice conditions have played a paramount role in the field development plans. An example is the consequences of iceberg threaten in an area and the effect sudden changes in ice drift directions may have on the exploration and drilling solutions chosen. The paper will also discuss how to derive design ice actions values for such waters including scaling from nature to model ice basins.

Løset, S.

2009-04-01

138

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

E-print Network

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

Eicken, Hajo

139

A Theoretically Based Parameterization of Snow and Ice Broadband Albedo  

Microsoft Academic Search

Under most atmospheric conditions, absorption of shortwave radiation is the largest energy source for melting snow and ice. The amount of shortwave radiation absorbed is dependent on both the incident radiation and the surface albedo, both of which are highly variable in space and time. It is therefore critical to incorporate the temporal variability of snow\\/ice albedo in numerical models

A. S. Gardner; M. J. Sharp

2009-01-01

140

A Theoretically Based Parameterization of Snow and Ice Broadband Albedo  

NASA Astrophysics Data System (ADS)

Under most atmospheric conditions, absorption of shortwave radiation is the largest energy source for melting snow and ice. The amount of shortwave radiation absorbed is dependent on both the incident radiation and the surface albedo, both of which are highly variable in space and time. It is therefore critical to incorporate the temporal variability of snow/ice albedo in numerical models of the surface energy balance. Despite the strong influence of snow and ice albedo on climate, surface energy balance, and melt rates, there is little consensus on which albedo parameterizations are most appropriate for large scale modeling. This has motivated the development of a computationally simple, theoretically-based parameterization for the broadband albedo of snow and ice that can accurately reproduce the theoretical broadband albedo under a wide range of snow, ice, and atmospheric conditions. Depending on its application, this parameterization requires between one and five input parameters. These parameters are: specific surface area of snow/ice, concentration of light-absorbing carbon, solar zenith angle, cloud optical thickness, and snow depth. The parameterization is derived by fitting equations to albedo estimates generated with a 16-stream plane-parallel, discrete ordinates radiative transfer model of snow and ice that is coupled to a similar model of the atmosphere. Output from this model is also used to establish the physical determinants of the spectral albedo of snow and ice and evaluate the characteristics of spectral irradiance over snow-covered surfaces. Broadband albedo estimates determined from the radiative transfer model are compared with results from a selection of previously proposed parameterizations. Compared to these parameterizations, the newly proposed parameterization produces accurate results for a much wider range of snow/ice and atmospheric conditions.

Gardner, A. S.; Sharp, M. J.

2009-12-01

141

Numerical modeling of sea ice in the climate system  

E-print Network

in anthropogenic CO2 levels has been a growing concern for the loss of ice and snow in the polar regions. The loss, University of Washington Worldwide emissions of CO2 from human energy-related activities are currently aboutNumerical modeling of sea ice in the climate system by Cecilia M. Bitz Atmospheric Sciences

Bitz, Cecilia

142

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

NASA Technical Reports Server (NTRS)

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

Yung, Yuk L.

2004-01-01

143

Sea Level: Ice Volume Changes  

NSDL National Science Digital Library

In this exercise, students observe simulations of melting sea ice and a melting continental ice sheet in order to investigate the relationship between the melting of the ice and the water level in the tank. The water tanks simulate the world oceans. In the first example, the ice is floating in water. This would be an example of icebergs or Arctic ice floating on the ocean. In the second example the ice lies on a wood structure. The structure simulates a continent. The block of ice on top of the structure simulates ice grounded on top of a continent. This would be an example of ice sheets in Greenland and Antarctica.

144

Sea ice and polar climate in the NCAR CSM  

SciTech Connect

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.

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

145

Radiative transfer in atmosphere-sea ice-ocean system  

SciTech Connect

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.

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

146

The permanent presence of sea ice, ice sheets and continuous permafrost are defining features of the  

E-print Network

The permanent presence of sea ice, ice sheets and continuous permafrost are defining features of ­106 km2 over the past decade. The 2008/09 Arctic snow-cover season marked a continuation of relatively a general increase in permafrost temperatures during the last several decades in Alaska, northwest Canada

Bhatt, Uma

147

Modeling of Antarctic sea ice in a general circulation model  

SciTech Connect

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

Wu, Xingren; Budd, W.F. [Antarctic Cooperative Research Centre, Tasmania (Australia)] [Antarctic Cooperative Research Centre, Tasmania (Australia); Simmonds, I. [School of Earth Sciences, Victoria (Australia)] [School of Earth Sciences, Victoria (Australia)

1997-04-01

148

Snow and Ice Control Best Management Practices Parking Lots, Sidewalks, Roads  

E-print Network

Snow and Ice Control Best Management Practices Parking Lots, Sidewalks, Roads Minnesota Circuit opportunity to improve the way we manage snow and ice in Minnesota. By using snow and ice control best safer--while saving money and protecting water quality. Current Situation The snow and ice maintenance

Minnesota, University of

149

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

NASA Astrophysics Data System (ADS)

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.

Jeffery, N.; Hunke, E. C.

2014-09-01

150

Does black carbon and humic materials in snow and ice Supervisor: Martin D. King  

E-print Network

springs and loss of sea-ice in the Arctic. The Intergovernmental Panel on Climate Change listed the uncertainty of this radiative forcing causing climate change in Polar regions requires parameterization of the effect of Black carbon on snow so that it can be included in global climate models and its true effect

Royal Holloway, University of London

151

An ice-binding protein from an Antarctic sea ice bacterium.  

PubMed

An Antarctic sea ice bacterium of the Gram-negative genus Colwellia, strain SLW05, produces an extracellular substance that changes the morphology of growing ice. The active substance was identified as a approximately 25-kDa protein that was purified through its affinity for ice. The full gene sequence was determined and was found to encode a 253-amino acid protein with a calculated molecular mass of 26,350 Da. The predicted amino acid sequence is similar to predicted sequences of ice-binding proteins recently found in two species of sea ice diatoms and a species of snow mold. A recombinant ice-binding protein showed ice-binding activity and ice recrystallization inhibition activity. The protein is much smaller than bacterial ice-nucleating proteins and antifreeze proteins that have been previously described. The function of the protein is unknown but it may act as an ice recrystallization inhibitor to protect membranes in the frozen state. PMID:17651136

Raymond, James A; Fritsen, Christian; Shen, Kate

2007-08-01

152

Surface Albedo of the Antarctic Sea Ice Zone.  

NASA Astrophysics Data System (ADS)

In three ship-based field experiments, spectral albedos were measured at ultraviolet, visible, and near-infrared wavelengths for open water, grease ice, nilas, young “grey” ice, young grey-white ice, and first-year ice, both with and without snow cover. From the spectral measurements, broadband albedos are computed for clear and cloudy sky, for the total solar spectrum as well as for visible and near-infrared bands used in climate models, and for Advanced Very High Resolution Radiometer (AVHRR) solar channels. The all-wave albedos vary from 0.07 for open water to 0.87 for thick snow-covered ice under cloud. The frequency distribution of ice types and snow coverage in all seasons is available from the project on Antarctic Sea Ice Processes and Climate (ASPeCt). The ASPeCt dataset contains routine hourly visual observations of sea ice from research and supply ships of several nations using a standard protocol. Ten thousand of these observations, separated by a minimum of 6 nautical miles along voyage tracks, are used together with the measured albedos for each ice type to assign an albedo to each visual observation, resulting in “ice-only” albedos as a function of latitude for each of five longitudinal sectors around Antarctica, for each of the four seasons. These ice albedos are combined with 13 yr of ice concentration estimates from satellite passive microwave measurements to obtain the geographical and seasonal variation of average surface albedo. Most of the Antarctic sea ice is snow covered, even in summer, so the main determinant of area-averaged albedo is the fraction of open water within the pack.

Brandt, Richard E.; Warren, Stephen G.; Worby, Anthony P.; Grenfell, Thomas C.

2005-09-01

153

Sea Ice on the Southern Ocean  

NASA Technical Reports Server (NTRS)

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

Jacobs, Stanley S.

1998-01-01

154

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

NASA Astrophysics Data System (ADS)

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.

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

2005-06-01

155

Albedo over snow and ice penitents  

NASA Astrophysics Data System (ADS)

Both satellite and ground-based broadband albedo measurements over complex terrain show several limitations concerning feasibility and representativeness. In this study a series of experiments on Glaciar Tapado in the semi-arid Andes of Northern Chile is used to investigate the vertical dependence of albedo over a penitent-covered surface. The albedo-height relationship depends on the surface properties: over medium-sized snow penitents albedo increases with height, whereas over ice penitents little changes were found above the penitent tips and varying responses within the penitent troughs. The governing factor is the surface geometry and the ratio of penitent height to distance between their tips. Based on a model experiment it is shown that large parts of the variations above the tips can be explained geometrically, by varying influence of a confined albedo anomaly on a hemispherical sensor. Furthermore, the temporal evolution of broadband albedo over a penitent-covered surface is analyzed. In this context the albedo throughout two ablation seasons is discussed to place the experiments into a larger temporal context. Albedo measurements at an automated weather station show that broadband albedo over a penitents is low compared to expected values on a smooth surface. Albedo decreases early in the ablation season, and stabilizes from February onwards with variations being caused by fresh snow-fall events. The 2009/2010 and 2011/2012 seasons differ notably, where the latter shows lower albedo related to a different penitent evolution resulting in larger penitents. Finally, a comparison of the ground-based albedo observations with Landsat and MODIS-derived albedo showed that both satellite derived albedo products capture the albedo evolution with root mean square errors of 0.08 and 0.15, respectively, but also illustrate their shortcomings related to temporal resolution and spatial heterogeneity over mountain glaciers.

Abermann, J.; Kinnard, C.; Lhermitte, S.

2013-07-01

156

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

SciTech Connect

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.

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

1995-09-01

157

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

158

Arctic sea ice decay simulated for a CO 2 -induced temperature rise  

Microsoft Academic Search

A large scale numerical time-dependent model of sea ice that takes into account the heat fluxes in and out of the ice, the seasonal occurrence of snow, and ice motions has been used in an experiment to determine the response of the Arctic Ocean ice pack to a warming of the atmosphere. The degree of warming specified is that expected

Claire L. Parkinson; William W. Kellogg

1979-01-01

159

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

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

160

Albedo over rough snow and ice surfaces  

NASA Astrophysics Data System (ADS)

Surface albedo determines the shortwave radiation balance, arguably the largest energy balance component of snow and ice surfaces. Consequently, incorporation of the spatio-temporal variability of albedo is essential when assessing the surface energy balance of snow and ice surfaces. This can be done by using ground-based measurements or albedo data derived from remote sensing, or by modelling albedo based on radiative transfer models or empirically based parameterizations. One decisive factor when incorporating albedo data is the representativeness of surface albedo, certainly over rough surfaces where albedo measurements at a specific location (i.e., apparent albedo) can differ strongly from the material albedo or the true albedo (i.e., effective albedo) depending on the position of the sun/sensor and the surface roughness. This stresses the need for a comprehensive understanding of the effect of surface roughness on albedo and its impact when using albedo data for validation of remote sensing imagery, interpretation of automated weather station (AWS) radiation data or incorporation in energy balance models. To assess the effect of surface roughness on albedo an intra-surface radiative transfer (ISRT) model was combined with albedo measurements on a penitente field on Glaciar Tapado in the semi-arid Andes of Northern Chile. The ISRT model shows albedo reductions between 0.06 and 0.35 relative to flat surfaces with a uniform material albedo. The magnitude of these reductions primarily depends on the penitente geometry, but the shape and spatial variability of the material albedo also play a major role. Secondly, the ISRT model was used to reveal the effect of using apparent albedo to infer the effective albedo over a rough surface. This effect is especially strong for narrow penitentes, resulting in sampling biases up to ±0.05. The sampling biases are more pronounced when the sensor is low above the surface, but remain relatively constant throughout the day. Consequently, the only beneficial approach to minimize the sampling bias of surface albedo over rough surfaces is to use a large number of samples at various places. Thirdly, the temporal evolution of broadband albedo over a penitente-covered surface was analyzed to place the experiments and their uncertainty into a larger temporal context. Time series of albedo measurements at an automated weather station over two seasons reveal albedo decreases early in the ablation season. These decreases stabilize from February onwards with variations being caused by fresh snow-fall events. The 2009/2010 and 2011/2012 seasons differ notably, where the latter shows lower albedo caused by larger penitentes. Finally, a comparison of the ground-based albedo observations with Landsat and MODIS-derived albedo showed that both satellite derived albedo products capture the albedo evolution with root mean square errors of 0.08 and 0.15, respectively, but also illustrate their shortcomings related to temporal resolution and spatial heterogeneity over mountain glaciers.

Lhermitte, Stef; Abermann, Jakob; Kinnard, Christophe

2014-05-01

161

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

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

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

2005-01-01

162

Cladoceran zooplankton abundance under clear and snow-covered ice  

USGS Publications Warehouse

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

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

2003-01-01

163

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

Microsoft Academic Search

The radiative and turbulent heat fluxes between the snow-covered sea ice and the atmosphere were analyzed on the basis of observations during the Ice Station Polarstern (ISPOL) in the western Weddell Sea from 28 November 2004 to 2 January 2005. The net heat flux to the snowpack was 3 ± 2 W m?2 (mean ± standard deviation; defined positive toward

Timo Vihma; Milla M. Johansson; Jouko Launiainen

2009-01-01

164

Snow and ice volume on Mount Spurr Volcano, Alaska, 1981  

USGS Publications Warehouse

Mount Spurr (3,374 meters altitude) is an active volcano 130 kilometers west of Anchorage, Alaska, with an extensive covering of seasonal and perennial snow, and glaciers. Knowledge of the volume and distribution of snow and ice on a volcano aids in assessing hydrologic hazards such as floods, mudflows, and debris flows. In July 1981, ice thickness was measured at 68 locations on the five main glaciers of Mount Spurr: 64 of these measurements were made using a portable 1.7 megahertz monopulse ice-radar system, and 4 measurements were made using the helicopter altimeter where the glacier bed was exposed by ice avalanching. The distribution of snow and ice derived from these measurements is depicted on contour maps and in tables compiled by altitude and by drainage basins. Basal shear stresses at 20 percent of the measured locations ranged from 200 to 350 kilopascals, which is significantly higher than the 50 to 150 kilopascals commonly referred to in the literature as the 'normal' range for glaciers. Basal shear stresses higher than 'normal' have also been found on steep glaciers on volcanoes in the Cascade Range in the western United States. The area of perennial snow and ice coverage on Mount Spurr was 360 square kilometers in 1981, with an average thickness of 190?50 meters. Seasonal snow increases the volume about 1 percent and increases the area about 30 percent with a maximum in May or June. Runoff from Mount Spurr feeds the Chakachatna River and the Chichantna River (a tributary of the Beluga River). The Chakachatna River drainage contains 14 cubic kilometers of snow and ice and the Chichantna River drainage contains 53 cubic kilometers. The snow and ice volume on the mountain was 67?17 cubic kilometers, approximately 350 times more snow and ice than was on Mount St. Helens before its May 18, 1980, eruption, and 15 times more snow and ice than on Mount Rainier, the most glacierized of the measured volcanoes in the Cascade Range. On the basis of these relative quantities, hazard-producing glaciovolcanic phenomena at Mount Spurr could be significantly greater than similar phenomena at Cascade Volcanoes.

March, Rod S.; Mayo, Lawrence R.; Trabant, Dennis C.

1997-01-01

165

Physical characteristics of summer sea ice across the Arctic Ocean  

USGS Publications Warehouse

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

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

1999-01-01

166

Kindergarten Explorations with Snow, Ice, and Water  

ERIC Educational Resources Information Center

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

Carroll, Martha A.

1978-01-01

167

Arctic Sea Ice Satellite Observations  

NSDL National Science Digital Library

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.

Foundation, Wgbh E.

2008-01-17

168

Ice2sea initial progress  

NASA Astrophysics Data System (ADS)

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

Ford, Elaina; Vaughan, David

2010-05-01

169

Arctic sea ice microwave signature and geophysical processes study  

NASA Technical Reports Server (NTRS)

Studies on the validation and utilization of ERS-1 SAR (Synthetic Aperture Radar) derived liquid and solid ocean information and the study of the interregional, regional, and temporal variation of the microwave signatures of sea ice and snow, are reported. Initial interests are focused on the accuracy of the estimates of ice type, ice form, deformation state, or thickness, and the ability to retrieve ice physical property information. Two in situ campaigns were conducted for the purpose of 'truth' ERS-1 SAR products and to gather data in support of the above science studies.

Onstott, Robert G.; Shuchman, Robert A.

1993-01-01

170

Short pulse radar measurements of layered ice and snow  

NASA Technical Reports Server (NTRS)

Using a radar system with high range resolution, it was shown that measurements of snow and ice thickness are feasible with an accuracy of better than 3 inches. In addition, the water equivalent of the snowpack can be estimated, given a single surface measurement of the snow depth. Discontinuities in density were also detected and their location determined by inspection of the radar returns. The remote measurement of layer thickness is described. The system was designed for eventual incorporation into a light aircraft.

Vickers, R. S.; Rose, G. C.

1972-01-01

171

Melting Ice, Rising Seas  

NASA Video Gallery

Sea level rise is an indicator that our planet is warming. Much of the world's population lives on or near the coast, and rising seas are something worth watching. Sea level can rise for two reason...

172

Evidence of Ice Free Seas  

NSDL National Science Digital Library

In this activity, students make a model sea floor sediment core using two types of buttons to represent fossil diatoms. They then compare the numbers of diatom fossils in the sediment at different depths to determine whether the seas were free of ice while the diatoms were alive.

Dahlman, Luann; Andrill

173

Blue-ice and snow runways <  

NSF Publications Database

... and compacted-snow runways in general, as well as current proposals to develop such runways at the ... This analysis will be reviewed for future developments, and supplemental analysis and documentation ...

174

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

NSDL National Science Digital Library

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.

Bhat, Venugopal; Plans, Nasa -.

175

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

E-print Network

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

Feltham, Daniel

176

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

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

2014-07-01

177

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

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

2014-07-01

178

Variability of Arctic Sea Ice as Viewed from Space  

NASA Technical Reports Server (NTRS)

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

Parkinson, Claire L.

1998-01-01

179

Observed and Modeled Trends in Southern Ocean Sea Ice  

NASA Technical Reports Server (NTRS)

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

Parkinson, Claire L.

2003-01-01

180

ICESat Observations of Arctic Sea Ice: A First Look  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

181

ICESat Observations of Arctic Sea Ice: A First Look  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

182

Water, Ice, and Snow - Issue 5, August 2008  

NSDL National Science Digital Library

In this issue of the free online magazine, Beyond Penguins and Polar Bears, explore what the polar regions can teach us about the water cycle and the states and changes of matter. Find lesson plans about the many forms of water, ice, and snow found in the polar regions and how to use science notebooks to integrate literacy and science.

University, The O.

183

Soot climate forcing via snow and ice albedos  

Microsoft Academic Search

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 \\

James Hansen; Larissa Nazarenko

2004-01-01

184

Soot climate forcing via snow and ice albedos James Hansen*  

E-print Network

Soot climate forcing via snow and ice albedos James Hansen* and Larissa Nazarenko* *National Institute, 2880 Broadway, New York, NY 10025 Contributed by James Hansen, November 4, 2003 Plausible land areas) yield a climate forcing of 0.3 W m2 in the Northern Hemisphere. The ``efficacy

185

Ice nucleation: elemental identification of particles in snow crystals.  

PubMed

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

Parungo, F P; Pueschel, R F

1973-06-01

186

Sea Ice Index  

NSDL National Science Digital Library

This site presents average ice conditions estimated using satellite passive microwave data for the most recent month available, as well as snapshots of trends and anomalies that compare these recent conditions with the mean for the month.

Fetterer, Florence

187

AMSR2 Daily Arctic Sea Ice - 2014  

NASA Video Gallery

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

188

Ice Tank Experiments Highlight Changes in Sea Ice Types  

NASA Astrophysics Data System (ADS)

With the current and likely continuing reduction of summer sea ice extent in the Arctic Ocean, the predominant mechanism of sea ice formation in the Arctic is likely to change in the future. Although substantial new ice formation occurred under preexisting ice in the past, the fraction of sea ice formation in open water likely will increase significantly. In open water, sea ice formation starts with the development of small ice crystals, called frazil ice, which are suspended in the water column [World Meteorological Organization, 1985]. Under quiescent conditions, these crystals accumulate at the surface to form an unbroken ice sheet known in its early stage as nilas. Under turbulent conditions, caused by wind and waves, frazil ice continues to grow and forms into a thick, soupy mixture called grease ice. Eventually the frazil ice will coalesce into small, rounded pieces known as pancake ice, which finally consolidate into an ice sheet with the return of calm conditions. This frazil/pancake/ice sheet cycle is currently frequently observed in the Antarctic [Lange et al., 1989]. The cycle normally occurs in regions that have a significant stretch of open water, because this allows for the formation of larger waves and hence increased turbulence. Given the increase of such open water in the Arctic Ocean caused by retreating summer sea ice, the frazil/pancake/ice sheet cycle may also become the dominant ice formation process during freezeup in the Arctic.

Wilkinson, Jeremy P.; DeCarolis, Giacomo; Ehlert, Iris; Notz, Dirk; Evers, Karl-Ulrich; Jochmann, Peter; Gerland, Sebastian; Nicolaus, Marcel; Hughes, Nick; Kern, Stefan; de la Rosa, Sara; Smedsrud, Lars; Sakai, Shigeki; Shen, Hayley; Wadhams, Peter

2009-03-01

189

Microstructural Considerations of Transporting Sea Ice Samples from Polar Regions  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

190

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

NASA Technical Reports Server (NTRS)

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.

1998-01-01

191

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

NASA Technical Reports Server (NTRS)

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

1997-01-01

192

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

Microsoft Academic Search

The abundances and distribution of metazoan within-ice meiofauna (13 stations) and under-ice fauna (12 stations) were investigated in level sea ice and sea-ice ridges in the Chukchi\\/Beaufort Seas and Canada Basin in June\\/July 2005 using a combination of ice coring and SCUBA diving. Ice meiofauna abundance was estimated based on live counts in the bottom 30cm of level sea ice

Rolf Gradinger; Bodil Bluhm; Katrin Iken

2010-01-01

193

Sensitivity of Antarctic sea ice to form drag parameterization  

NASA Astrophysics Data System (ADS)

A new drag parametrization accounting explicitly for form drag has been recently formulated and applied to the Arctic sea ice (Lupkes et al, 2012 and Tsamados et al, 2014). We summarize here the fundamental elements of this formulation and we then adapt it to the Antarctic sea ice. Considering the general expression of the momentum balance of sea ice, we analyze the total (neutral) drag coefficients by studying separately air-ice and ocean-ice momentum fluxes, and by introducing the parameterization for both the atmospheric neutral drag coeffcient (ANDC) and the oceanic neutral drag coeffcient (ONDC). The two coefficients are calculated as a sum of their skin frictional contribution and form drag contribution, which comes from ridges and floe edges for the ANDC and keels and floe edges for the ONDC. Due to the contrasting geography of the two polar regions, there are important differences, both dynamic and thermodynamic, between Arctic and Antarctic sea ice. In the Antarctic, sea ice is younger, less ridged (hence thinner and smoother). Due to the intense snowfalls, the snow cover is generally thicker than in the Arctic, with values that vary significantly both seasonally and regionally and can affect the roughness of the surface and can lead to flooding of the ice. At the outer boundary of the Southern Ocean, the ice is unconstrained by land, divergent and subject to meridional advection, which leads to a much faster ice drift than in the Arctic. We show here how the new parameterization accounting for form drag influences the Antarctic sea ice characteristics.

Barbic, Gaia; Tsamados, Michel; Petty, Alek; Schroeder, David; Holland, Paul; Feltham, Daniel

2014-05-01

194

Arctic Sea Ice Extent Plummets in 2007  

Microsoft Academic Search

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

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

2008-01-01

195

3, 9991020, 2007 Summer sea ice  

E-print Network

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

Boyer, Edmond

196

Surface Impedance Tomography for Antarctic Sea Ice  

E-print Network

Surface Impedance Tomography for Antarctic Sea Ice C. Sampsona , K. M. Goldena , A. Gullya , A. P measured the electrical conductivity of sea ice via surface impedance tomography. Resistance data from, this approach assumes that the conductivity profile of sea ice does not change very much with depth. In order

Golden, Kenneth M.

197

Sea Ice Rheology Daniel L. Feltham  

E-print Network

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

Feltham, Daniel

198

Recent State of Arctic Sea Ice  

Microsoft Academic Search

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

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

199

Wind waves in ice-free areas of Arctic seas.  

NASA Astrophysics Data System (ADS)

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

Golubkin, Pavel; Chapron, Bertrand; Kudryavtsev, Vladimir

200

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...

2008-12-29

201

Passive microwave data for snow and ice research - Planned products from the DMSP SSM/I system  

NASA Technical Reports Server (NTRS)

Recommendations which have been made for processing and distributing passive microwave data for snow and ice research obtained with the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I) are discussed. The general objectives for SSM/I data are reviewed, and the sensor and data flow are described. The SSM/I sea ice products are discussed, and algorithm/product validation is addressed. Proposed services and implementation after SSM/I launch are summarized.

Weawer, Ronald; Barry, Roger G.; Morris, Charles

1987-01-01

202

Validation of EOS Aqua AMSR Sea Ice Products for East Antarctica  

NASA Technical Reports Server (NTRS)

This paper presents results from AMSR-E validation activities during a collaborative international cruise onboard the RV Aurora Australis to the East Antarctic sea ice zone (64-65 deg.S, 110-120 deg.E) in the early Austral spring of 2003. The validation strategy entailed an IS-day survey of the statistical characteristics of sea ice and snowcover over a Lagrangian grid 100 x 50 km in size (demarcated by 9 drifting ice beacons) i.e. at a scale representative of Ah4SR pixels. Ice conditions ranged h m consolidated first-year ice to a large polynya offshore from Casey Base. Data sets collected include: snow depth and snow-ice interface temperatures on 24 (?) randomly-selected floes in grid cells within a 10 x 50 km area (using helicopters); detailed snow and ice measurements at 13 dedicated ice stations, one of which lasted for 4 days; time-series measurements of snow temperature and thickness at selected sites; 8 aerial photography and thermal-IR radiometer flights; other satellite products (SAR, AVHRR, MODIS, MISR, ASTER and Envisat MERIS); ice drift data; and ancillary meteorological (ship-based, meteorological buoys, twice-daily radiosondes). These data are applied to a validation of standard AMSR-E ice concentration, snowcover thickness and ice-temperature products. In addition, a validation is carried out of ice-surface skin temperature products h m the NOAA AVHRR and EOS MODIS datasets.

Massom, Rob; Lytle, Vicky; Allison, Ian; Worby, Tony; Markus, Thorsten; Scambos, Ted; Haran, Terry; Enomoto, Hiro; Tateyama, Kazu; Pfaffling, Andi

2004-01-01

203

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)

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.

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

2010-05-01

204

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

NASA Astrophysics Data System (ADS)

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.

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

2008-04-01

205

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

NASA Astrophysics Data System (ADS)

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.

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

206

Changes in Sea Ice: Antarctic vs. Arctic  

NASA Astrophysics Data System (ADS)

Since the dramatic retreat of Arctic sea ice in summer 2007, the summer extent of the Arctic sea ice cover has been at the lowest levels on record, with a new record minimum seen in 2012. The steep decline occurred after years of shrinking and thinning of the ice cover not only in summer but also in other seasons. Meanwhile, satellite passive microwave images show that there has been a modest net increase in the Antarctic sea ice extent since 1979. This upward trend is caused by a significant increase in ice concentration in most of the Indian sector and parts of the Atlantic and Pacific sectors including areas in the Weddell and Ross seas, as shown by satellite ice concentration data. However, satellite data also show that ice concentration has decreased considerably in some areas in the Atlantic and Pacific sectors, particularly around the Antarctic Peninsula. This highlights the complex variability and trend patterns of the Antarctic sea ice cover. In an effort to shed light on the behavior of the Antarctic sea ice cover, a comparative model study is conducted to examine its variability and trends relative to the behavior of the Arctic sea ice cover over 1979-2012, using the Global Ice-Ocean Modeling and Assimilation System (GIOMAS). We compare changes in sea ice extent, volume, motion, deformation, internal interaction, ridging, growth, and melt in both polar regions. We also explore the differences in sea ice response to changes in atmospheric and oceanic forcing in the polar regions.

Zhang, J.

2013-12-01

207

Creating Arctic Sea Ice Protected Areas?  

NASA Astrophysics Data System (ADS)

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.

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

2008-12-01

208

The influence of cloud cover on the radiation budget, physical properties, and microwave scattering coefficient (?°) of first-year and multiyear sea ice  

Microsoft Academic Search

Over sea ice, the shift from predominantly clear conditions in winter to persistent stratus cloud cover in late spring and early summer coincides with a dramatic increase in the net radiation balance at the sea ice surface. Transformation of the boundary layer climate and the geophysical properties of the snow covered sea ice result from this cloud-induced rise in surface

David G. Barber; Andrew Thomas

1998-01-01

209

Antarctic sea ice mapping using the AVHRR  

SciTech Connect

A sea ice mapping scheme based on Advanced Very High Resolution Radiometer (AVHRR) data from the National Oceanic and Atmospheric Administration (NOAA) polar orbiting satellites has been developed and applied to daylight images taken between November 1989 to January 1990 and November 1990 to January 1991 over the Weddell and the Ross Seas. After masking the continent and ice shelves, sea ice is discriminated from clouds and open sea using thresholds applied to the multidimensional space formed by AVHRR Channel 2, 3, and 4 radiances. Sea ice concentrations in cloud-free regions are then computed using the tie-point method. Results based on the analysis of more than 70 images show that the proposed scheme is capable of properly discriminating between sea ice, open sea, and clouds, under most conditions, thus allowing high resolution sea ice maps to be produced during the austral summer season.

Zibordi, G. (Inst. for the Study of Geophysical and Environmental Methodologies, Modena (Italy)); Van Woert, M.L. (San Diego State Univ., CA (United States). SeaSpace, Inc.)

1993-08-01

210

An investigation of the small ice cap instability in the Southern Hemisphere with a coupled atmosphere-sea ice-ocean-terrestrial ice model  

Microsoft Academic Search

A simple climate model has been developed to investigate the existence of the small ice cap instability in the Southern Hemisphere.\\u000a The model consists of four coupled components: an atmospheric energy balance model, a thermodynamic snow-sea ice model, an\\u000a oceanic mixed layer model and a terrestrial ice model. Results from a series of experiments involving different degrees of\\u000a coupling in

M. A. Morales Maqueda; A. J. Willmott; J. L. Bamber; M. S. Darby

1998-01-01

211

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

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

212

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

NASA Astrophysics Data System (ADS)

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.

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

2009-12-01

213

Antarctic Sea Ice in the IPY  

Microsoft Academic Search

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

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

2003-01-01

214

Extraction of winter total sea-ice concentration in the Greenland and Barents Seas from SSM\\/I data  

Microsoft Academic Search

Significantly different sea-ice concentrations estimated by the well known Bootstrap and NASA\\/Team SSM\\/I algorithms are found to occur when the brightness temperature of horizontally polarized radiation is depressed, possibly as a result of ice layers in the snow cover. Furthermore, discontinuous ice concentrations, which do not reflect real concentration variations, sometimes occur when the Bootstrap algorithm switches between polarization and

D. M. SMITH

1996-01-01

215

Satellite remote sensing over ice  

Microsoft Academic Search

Satellite remote sensing provides unique opportunities for observing ice- covered terrain. Passive microwave data give information on snow cover on land, sea ice extent and type, and zones of summer melting on the polar ice sheets, and they have the potential of estimating snow accumulation rates on these ice sheets. All-weather, high-resolution imagery of sea ice is obtained by using

Robert H. Thomas

1986-01-01

216

Snow  

NSDL National Science Digital Library

Snow can be one of the most destructive forces in nature but also one of the most fun to learn about. An article from Associated Press writer Lourdes Navarro, featured in the Minneapolis Star Tribune, describes the avalanche in the Hindu Kush Mountains in Afghanistan. Avalanche.org's Web site offers visitors up-to-date avalanche information for the western US and one area in the east, as well as accident statistics and additional links. The NOVA site Avalanche has a Snow Sense link that gives practical advice on maximizing your safety in avalanche terrain and even rescue techniques. For those interested in data related to snow, ice, glaciers, and more, the National Snow and Ice Data Center (NSIDC) compiles and distributes such records to the public in this extensive site. The Alaska Climate Research Center, which is funded by the State of Alaska, contains a weather web cam, a link to Alaskan climatology, and even long term climatological records. The next site, from DiscoverySchool.com, is a lesson plan geared for students in the 6-8 grade called Avalanche. The activity involves learning the necessary conditions that create an avalanche, such as lack of friction. More lesson plans from snowschool.com include snow melting and snow density lesson plans, geared for students between the grades of 2-6. The final site Snow Crystals, created by California Institute of Technology Physics Professor Kenneth G. Libbrecht, is a terrific site dedicated to snow crystals and snowflakes, showing "how these remarkably complex and beautiful structures appear, quite literally, out of thin air." The site is definitely worth a look for anyone interested in snow and snowflakes.

Brieske, Joel A.

2002-01-01

217

A Novel and Low Cost Sea Ice Mass Balance Buoy.  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

218

Microwave signatures of snow, ice and soil at several wavelengths  

NASA Technical Reports Server (NTRS)

Analyses of data obtained from aircraft-borne radiometers have shown that the microwave signatures of various parts of the terrain depend on both the volume scattering cross-section and the dielectric loss in the medium. In soil, it has been found that experimental data fit a model in which the scattering cross section is negligible compared to the dielectric loss. On the other hand, the volume scattering cross-section in snow and continental ice was found, from analyzing data obtained with aircraft- and spacecraft-borne radiometers, to be more important than the dielectric loss or surface reflectivity in determining the observed microwave emissivity. A model which assumes Mie scattering of ice particles of various sizes was found to be the dominant volume scattering mechanism in these media. Both spectral variation in the microwave signatures of snow and ice fields, as well as the variation in the emissivity of continental ice sheets such as those covering Greenland and Antarctica appear to be consistent with this model.

Gloersen, P.; Schmugge, T. J.; Chang, T. C.

1974-01-01

219

Sea Ice Lead Distribution from High Resolution Airborne Imagery  

NASA Astrophysics Data System (ADS)

NASA's Operation IceBridge Mission provides continuity of the sea ice thickness time series, between the now complete ICESat mission and the planned ICESat-2 mission, by utilizing airborne laser and radar altimetry measurements to improve estimates of snow and ice thickness. An essential step in deriving sea ice freeboard (and hence thickness) from altimetry measurements of sea ice elevation is the determination of local sea level. Discrimination of leads along-track is therefore critical for deriving the elevation of open water within leads and defining sea surface height. Here we provide an assessment of the lead mapping capabilities of the Digital Mapping System (DMS), a nadir-looking, high-resolution digital camera mounted on IceBridge aircraft. For a nominal aircraft operating-altitude around 500 m, the resolution of the DMS imagery is approximately 0.1 m. A novel lead detection algorithm was applied to DMS digital photography for unambiguous detection of leads within the sea ice pack and classification of lead type. The data were used to generate statistics on lead distribution and spacing, lead width, and areal coverage. We compare results from the Arctic multi-year ice pack with data gathered over the mainly seasonal ice pack of the Southern Ocean. We find that areal coverage of Antarctic leads is about 5 % and three times higher than in the Arctic (1.5 %). Both dynamic and thermodynamic modeling of the sea ice pack relies on knowledge of lead distribution to effectively model ice motion and interactions between the ocean and atmosphere. We describe the potential contribution our results can make towards the improvement of coupled ice-ocean numerical models. We discuss the application of lead discrimination for freeboard retrieval from satellite altimetry (e.g. CryoSat-2 and ICESat-2) and the use of lead distribution statistics for assessing sampling geometries employed by current airborne and future satellite laser altimeters to map the complex sea ice environment, including the multi-beam photon-counting approach proposed for ICESat-2.

Farrell, S. L.; Kurtz, N. T.; Onana, V.; Harbeck, J. P.; Duncan, K.

2011-12-01

220

The NASA IceBridge Project Quickly Delivers Snow and Ice Elevation Measurements of Dynamic Polar Landscapes  

NASA Astrophysics Data System (ADS)

NASA's Operation IceBridge was formulated to bridge the gap between the ICESat and ICESat-2 satellite missions. IceBridge data are collected by a wide variety of instrumentation aboard aircraft that trace routes around Greenland, Alaska and Antarctica, concentrating on areas experiencing accelerated change. Data parameters such as ice surface elevation, ice bottom elevation, snow and ice depth, grounding line position, sea ice distribution and freeboard are extracted at resolutions better than what can be expected by satellite. IceBridge provides the continuity of such data until the launch of the ICESat-2 satellite, expected in 2016. NSIDC manages the data distribution and makes the data available quickly and effectively to any and all interested parties. For example, the MCoRDS L1B Geolocated Radar Echo Strength Profiles data represents one of 60 total data products available through the IceBridge project. The MCoRDS L1B data for the Greenland 2012 campaign exhibit ice surface and ice bottom information for areas of Greenland between 27 March 2012 and 17 May 2012. In July of 2012, these data were made available on the NSIDC Web site, allowing users to begin analyzing the data only a couple of months after the data collection. The data are distributed in MATLAB files with associated PDF, TIFF and PNG files. Comparable data are available starting in 2009 for periodic campaigns covering both Greenland and Antarctica. These data can be combined with an array of other parameters to track the state of the most crucial areas of the Earth's cryosphere.

Tressel, S. S.; Kaminski, M. L.; Brodzik, M.

2012-12-01

221

How Does Melting Ice Affect Sea Level?  

NSDL National Science Digital Library

In this activity, students investigate how sea levels might rise when ice sheets and ice caps melt by constructing a pair of models and seeing the effects of ice melt in two different situations. Students should use their markers to predict the increase of water in each box before the ice melts.

Dahlman, Luann; Andrill

222

Photochemistry of phenanthrene, pyrene, and fluoranthene in ice and snow  

NASA Astrophysics Data System (ADS)

Although polycyclic aromatic hydrocarbons (PAHs) are common pollutants in snow, there is little quantitative data about their rates of photodegradation in this environment. To begin to address this gap, we have measured the degradation kinetics of phenanthrene, pyrene, and fluoranthene on ice, as these are the most abundant PAHs in arctic snow. Frozen aqueous solutions of individual PAHs, with and without added hydrogen peroxide (HOOH) as a source of hydroxyl radical ( rad OH), were illuminated with simulated sunlight. For all three PAHs, direct photodecay is the main mechanism of degradation, while rad OH-initiated indirect photodegradation is a minor sink. Rate constants (±1 SE) for direct photodegradation extrapolated to midday, surface snow conditions at Summit, Greenland on the summer solstice are 3.8 (±0.8) × 10 -5, 28 (±3) × 10 -5, and 1.4 (±0.7) × 10 -5 s -1 for phenanthrene, pyrene, and fluoranthene, respectively. Apparent quantum efficiencies for photodegradation with simulated sunlight were 3.8 (±0.8) × 10 -3, 4.3 (±0.5) × 10 -4, and 2 (±1) × 10 -5, respectively. Calculated PAH lifetimes in surface snow under Summit conditions are 1-19 h during mid-summer, but increase to >100 days in the dark winter. While the short photodegradation lifetimes in the summer suggest that there should be no appreciable PAH levels in this season, past measurements at Summit sometimes show significant levels of these PAHs in summer surface snow. This discrepancy is likely due to differences in PAH location between lab samples (where the PAHs are probably in quasi-liquid layers) and real snow (where PAHs are likely primarily associated with particulate matter).

Ram, Keren; Anastasio, Cort

223

The strength anisotropia of sea ice  

SciTech Connect

The hydraulic-engineering structure calculations of sea ice formation force require the sea ice strength data. The strength characteristics values and the types of sea ice formations in view of water depth define the type and the design of future structures in each particular region of supposed construction. The most objective information on the sea ice physical and technical properties can be obtained by field investigations ad the existing methods of their calculations refer to a great number of errors. The accumulated bank of data on studying the sea ice formation strength properties show one that ice as a natural material is of great crystalline structure variety. The level ice fields have a number of particularities. The crystal sizes increase in ice thickness. The crystals consist of fresh-water thin plates 0.5--0.6 mm in thickness oriented by pickle-water interlayers. Difference in thickness of the sea ice cover structure is one of the main causes of the changes strength characteristics layer. Besides that the sea ice strength depends upon the destroying force direction in reference to crystal orientation which characterizes the sea ice anisotropia as a material.

Evdokimov, G.N.; Rogachko, S.I. [Moscow State Univ. of Civil Engineering (Russian Federation)

1994-12-31

224

Halocarbons associated with Arctic sea ice  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

225

Arctic Sea Ice Changes 2011-2012  

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...

226

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....

2009-01-28

227

Distinguishing Clouds from Ice over the East Siberian Sea, Russia  

NASA Technical Reports Server (NTRS)

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

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

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

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

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

2002-01-01

228

Consolidation experiments on rafted sea ice  

NASA Astrophysics Data System (ADS)

Rafting is an important process in the deformation of sea ice that occurs when two ice sheets collide. This process is particularly common in the North Caspian Sea, where ice floes override one another multiple times to produce thick sea ice features. To date, rafting has received little attention in the literature perhaps because in most regions pressure ridges produce the greatest loads on offshore structures. In the North Caspian Sea the shallow waters constrain the size to which pressure ridges can grow and the low salinity seems to favour rafting over ridging. Therefore it is likely that multiply-rafted sea ice may be the governing design feature for ice loads in the Caspian Sea. In this paper we present a series of experiments that were carried out in the Rock and Ice Physics Laboratory at the University College London to investigate the consolidation of rafted sea ice. During an experiment, layers of laboratory grown sea ice were stacked on top of one another, with a thin layer of saline water between adjacent sheets, to simulate a section of rafted sea ice. The rate of consolidation was then monitored using a combination of temperature readings recorded in the ice and liquid layer, salinity measurements of the liquid layer, and cores taken using a manual core auger. Experiments were repeated several times whilst varying the ice thickness, liquid layer thickness, the number of ice layers in the stack, the salinity of the sea ice and liquid layer, and the ambient air temperature. These were then compared to larger scale experiments that were carried out in the Arctic Environmental Test Basin at the Hamburgische Schiffbau-Versuchsanstalt (HSVA) in Germany.

Bailey, E.; Sammonds, P.; Feltham, D.

2009-12-01

229

4, 107128, 2007 Sea-ice-drift  

E-print Network

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

Paris-Sud XI, Université de

230

Sea Ice, Climate and Fram Strait  

NASA Technical Reports Server (NTRS)

When sea ice is formed the albedo of the ocean surface increases from its open water value of about 0.1 to a value as high as 0.8. This albedo change effects the radiation balance and thus has the potential to alter climate. Sea ice also partially seals off the ocean from the atmosphere, reducing the exchange of gases such as carbon dioxide. This is another possible mechanism by which climate might be affected. The Marginal Ice Zone Experiment (MIZEX 83 to 84) is an international, multidisciplinary study of processes controlling the edge of the ice pack in that area including the interactions between sea, air and ice.

Hunkins, K.

1984-01-01

231

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

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

232

Characterization of ice binding proteins from sea ice algae.  

PubMed

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

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

2014-01-01

233

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

E-print Network

Variability and trends in sea ice extent and ice production in the Ross Sea Josefino C. Comiso,1 Ronald Kwok,2 Seelye Martin,3 and Arnold L. Gordon4 Received 7 May 2010; revised 6 December 2010; accepted 24 January 2011; published 21 April 2011. [1] Salt release during sea ice formation in the Ross

Gordon, Arnold L.

234

An Over-Sea-Ice Seismic Reflection Survey: Offshore New Harbor, Antarctica  

Microsoft Academic Search

During the austral spring of 2008, approximately 48 km of multi-channel seismic reflection data were collected on a sea-ice platform east of New Harbor, Antarctica. The Offshore New Harbor (ONH) survey is third in a series of three successful over-sea-ice seismic reflection surveys recently conducted in McMurdo Sound, Antarctica. For rapid data acquisition, the ONH project employed a 60-channel snow

D. A. Sunwall; M. A. Speece; S. F. Pekar; G. S. Wilson; K. J. Tinto

2009-01-01

235

The role of satellites in snow and ice measurements  

NASA Technical Reports Server (NTRS)

Earth-orbiting polar satellites are desirable platforms for the remote sensing of snow and ice. Geostationary satellites at a very high altitude (35,900 km) are also desirable platforms for many remote sensors, for communications relay, for flood warning systems, and for telemetry of data from unattended instrumentation in remote, inaccessible places such as the Arctic, Antarctic, or mountain tops. Optimum use of satellite platforms is achieved only after careful consideration of the temporal, spatial, and spectral requirements of the environmental mission. The National Environmental Satellite Service will maintain both types of environmental satellites as part of its mission.

Wiesnet, D. R.

1974-01-01

236

Unlocking a Sea Ice Secret  

SciTech Connect

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

Dr. Rachel Obbard

2013-04-22

237

Sea Ice and Products and Services of the National Ice Center  

NSDL National Science Digital Library

This two-hour module examines sea ice, icebergs, and the products and services of the National Ice Center and the North American Ice Service. Topics include climatology and current trends in sea ice extent and thickness; the development, classification, and drift of sea ice and icebergs; fractures, leads and polynyas; and the satellite detection of sea ice using visible, infrared, and microwave sensors.

Comet

2011-04-19

238

Ice core records as sea ice proxies: An evaluation from the Weddell Sea region of Antarctica  

NASA Astrophysics Data System (ADS)

Ice core records of methanesulfonic acid (MSA) from three sites around the Weddell Sea are investigated for their potential as sea ice proxies. It is found that the amount of MSA reaching the ice core sites decreases following years of increased winter sea ice in the Weddell Sea; opposite to the expected relationship if MSA is to be used as a sea ice proxy. It is also shown that this negative MSA-sea ice relationship cannot be explained by the influence that the extensive summer ice pack in the Weddell Sea has on MSA production area and transport distance. A historical record of sea ice from the northern Weddell Sea shows that the negative relationship between MSA and winter sea ice exists over interannual (˜7-year period) and multidecadal (˜20-year period) timescales. National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data suggest that this negative relationship is most likely due to variations in the strength of cold offshore wind anomalies traveling across the Weddell Sea, which act to synergistically increase sea ice extent (SIE) while decreasing MSA delivery to the ice core sites. Hence our findings show that in some locations atmospheric transport strength, rather than sea ice conditions, is the dominant factor that determines the MSA signal preserved in near-coastal ice cores. A cautious approach is thus required in using ice core MSA for reconstructing past sea ice conditions, including the need for networks of ice core records and multiproxy studies to assess the significance of past MSA changes at different locations around Antarctica.

Abram, Nerilie J.; Mulvaney, Robert; Wolff, Eric W.; Mudelsee, Manfred

2007-08-01

239

Springtime atmospheric transport controls Arctic summer sea-ice extent  

NASA Astrophysics Data System (ADS)

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).

Kapsch, Marie; Graversen, Rune; Tjernström, Michael

2013-04-01

240

The impact of the inclusion of new sea ice processes on the simulation of Arctic sea ice in CNRM-CM coupled model  

NASA Astrophysics Data System (ADS)

CNRM-CM3 AOGCM was one of the global coupled models which produced simulations in the framework of IPCC-AR4. It was shown that it failed in simulating the reduction in September Arctic sea ice extent observed during the late 20th century (e.g. Arzel et al, 2006). CNRM-CM3 actually simulated a slight increase in sea ice extent over 1980-1999. It was actually impossible to conclude whether this trend was due to natural variability or was a more robust model artefact, since only one realization of the simulated late 20th century Arctic climate was available. However, an analysis of IPCC AR4 simulations from a wide range of models suggested that this generation of AOGCMs, including CNRM-CM3 was not able to capture observed sea ice extent trends. The fifth version of CNRM-CM was developed in order to contribute to the IPCC AR5 set of climate simulations. CNRM-CM5 has a resolution of about 1° in the ocean, sea ice and atmosphere. In particular, as an attempt to improve the simulation of Arctic sea ice in CNRM-CM, the sea ice component of CNRM-CM5, Gelato, was upgraded. Sea ice salinity is now interactive; sea ice specific heat and heat conduction coefficient are functions of sea ice temperature and salinity. In both versions of the model, Gelato employs EVP dynamics (Hunke and Dukowicz, 1997) and has 4 sea ice categories. It has 10 vertical levels in the ice part of sea ice slabs, and one layer of snow. Ten simulations of the 1850-2012 period have been run with CNRM-CM5. A comparison with satellite data over 1979-1998 shows that CNRM-CM5 simulates the Arctic sea ice cover reasonably well. The modeled trend in Arctic summer sea ice extent varies significantly from one member to another, highlighting the contribution of variability to trends over a relatively short period. The spread of trends is however compatible with observations, an improvement compared to the previous version of the model, CNRM-CM3. In order to better understand this improvement and try to attribute it to upgrades in sea ice modelling, we ran sensitivity experiments, the reference being Gelato5 sea ice model as it was used in IPCC AR5 simulations. In each sensitivity experiment, one aspect of the sea ice model is downgraded: [1] back to a constant sea ice specific heat; [2] back to a constant heat conduction coefficient; [3] back to one sea ice category; [4] back to constant sea ice salinity. These simulations were carried out both in coupled mode (CNRM-CM5) and within the ocean-sea ice component of CNRM-CM5 (NEMO-Gelato ocean sea ice model) forced by ERA-Interim ECMWF reanalyses. These sensitivity experiments were run during 1990-2009, after a 20-yr spin-up. Based on these simulations, our conclusions are that different formulations of the physics of sea ice do not significantly alter the simulated global Arctic sea ice extent trend during 1990-2009. However, regional trends are generally modified in the sensitivity experiments compared to the control, since the geographic distribution of Arctic sea ice significantly changes.

Chevallier, M.; Salas y Melia, D.

2011-12-01

241

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

E-print Network

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

Long, David G.

242

6, 1105111066, 2006 Sea ice, frost flowers  

E-print Network

ACPD 6, 11051­11066, 2006 Sea ice, frost flowers and halogen activation W. R. Simpson et al. Title than potential frost flower contact W. R. Simpson 1 , D. Carlson 1 , G. Hoenninger 1,2, , T. A. Douglas. Simpson (ffwrs@uaf.edu) 11051 #12;ACPD 6, 11051­11066, 2006 Sea ice, frost flowers and halogen activation

Paris-Sud XI, Université de

243

Climate Kids: Planet Health Report: Sea Ice  

NSDL National Science Digital Library

One of Earth's vital signs, the extent of sea ice cover in the Arctic, is examined. An image and accompanying text describe the extent and consequences of the reduction in that sea ice. This article is part of the Climate Kids website, a NASA education resource featuring articles, videos, images and games focused on the science of climate change.

244

Forward electromagnetic scattering models for sea ice  

Microsoft Academic Search

Recent advances in forward modeling of the electromagnetic scattering properties of sea ice are presented. In particular, the principal results include the following: (1) approximate calculations of electromagnetic scattering from multilayer random media with rough interfaces, based on the distorted Born approximation and radiative transfer (RT) theory; (2) comprehensive theory of the effective complex permittivity of sea ice based on

K. M. Golden; M. Cheney; Kung-Hau Ding; A. K. Fung; Thomas C. Grenfell; D. Isaacson; Jin Au Kong; S. V. Nghiem; J. Sylvester; P. Winebrenner

1998-01-01

245

Antarctic Sea Ice in the IPY  

NASA Astrophysics Data System (ADS)

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 of several countries icebreaking research vessels over the last two decades. Useful knowledge of basic ice thickness, properties and processes is being addressed by an ice observations programs and several process studies, but the scale of activity is well below that conducted for the Arctic ice cover. The absence of submarine activity in the Antarctic which has provided large scale information on the changing Arctic ice thickness distribution is particularly notable as a critical measurement in understanding climate impact. As well, only two short term drift stations (Ice Station Weddell in 1992 and Ice Station Polarstern in 2004) have or will provide limited time series information on sea ice and ocean processes compared to multiple drift stations and yearlong experiments in the Arctic, dating back to IGY. The two technologies of Autonomous Underwater Vehicles specifically designed for long-range ice operations (500km) (e.g. Autosub Under Ice) and the recently developed international icebreaking research vessel capability for the Antarctic therefore gives an opportunity for two International Polar Year programs to provide critical information for the Antartic sea ice cover commensurate with our knowledge of the Arctic. The proposed programs are: 1. A circumpolar survey of the Antarctic sea ice thickness distribution at near maximum extent using two ship-based autonomous underwater vehicles and several countries' icebreakers. 2. An International Ice Drifting Station in the Bellingshausen-Amundsen-Ross Sea using icebreakers and drifting buoys to characterize the sea ice, ocean and climate in this unknown region of Antarctic multiyear ice. These measurements will provide directly comparable measurements to those of the Arctic Ocean' ice cover as well as a year-long snapshot of ice, ocean and climate conditions useful for numerical model verification for climate change prediction. New venues for training and experience of oceanographers, climate and sea ice scientists, and numerical modelers will also be provided to examine the many future opportunites in the Antarctic.

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

2003-12-01

246

A toy model of sea ice growth  

NASA Technical Reports Server (NTRS)

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

Thorndike, Alan S.

1992-01-01

247

Measurement and evolution of the thickness distribution and morphology of deformed features of Antarctic sea ice  

NASA Astrophysics Data System (ADS)

Antarctic sea ice thickness data obtained from drilling on sea ice floes were examined with the goal of enhancing our capability to estimate ice thickness remotely, especially from air- or space-borne altimetry and shipboard visual observations. The state of hydrostatic equilibrium of deformed ice features and the statistical relationships between ice thickness and top surface roughness were examined. Results indicate that ice thickness may be estimated fairly reliably from surface measurements of snow elevation on length scales of ?100 m. Examination of the morphology of deformed ice features show that Antarctic pressure ridges are flatter and less massive than Arctic pressure ridges and that not all surface features (ridge sails) are associated with features underwater (ridge keels). I propose that the differences in morphology are due to differences in sampling strategies, parent ice characteristics and the magnitude and duration of driving forces. As a result of these findings, the existing methodology used to estimate ice thickness from shipboard visual observations was modified to incorporate the probability that a sail is associated with a keel underwater, and the probability that keels may be found under level surfaces. Using the improved methodology, ice thickness was estimated from ship observations data obtained during two cruises in the Ross Sea, Antarctica. The dynamic and thermodynamic processes involved in the development of the ice prior to their observation were examined employing a regional sea ice-mixed layer-pycnocline model. Both our model results and previously published ice core data indicate that thermodynamic thickening is the dominant process that determines the thickness of first year ice in the central Ross Sea, although dynamic thickening also plays a significant role. Ice core data also indicate that snow ice forms a significant proportion of the total ice mass. For ice in the northeast Ross Sea in the summer, model results and evidence from ice core and oceanographic data indicate that dynamic thickening, snow ice formation and bottom melting compete to determine the ice thickness during mid and late winter.

Tin, Tina

248

Impacts of Declining Arctic Sea Ice: An International Challenge  

NASA Astrophysics Data System (ADS)

As reported by the National Snow and Ice Data Center in late August of 2008, Arctic sea ice extent had already fallen to its second lowest level since regular monitoring began by satellite. As of this writing, we were closing in on the record minimum set in September of 2007. Summers may be free of sea ice by the year 2030. Recognition is growing that ice loss will have environmental impacts that may extend well beyond the Arctic. The Arctic Ocean will in turn become more accessible, not just to tourism and commercial shipping, but to exploitation of oil wealth at the bottom of the ocean. In recognition of growing accessibility and oil operations, the United States Coast Guard set up temporary bases this summer at Barrow and Prudhoe Bay, AK, from which they conducted operations to test their readiness and capabilities, such as for search and rescue. The Canadians have been busy showing a strong Arctic presence. In August, a German crew traversed the Northwest Passage from east to west in one of their icebreakers, the Polarstern. What are the major national and international research efforts focusing on the multifaceted problem of declining sea ice? What are the areas of intersection, and what is the state of collaboration? How could national and international collaboration be improved? This talk will review some of these issues.

Serreze, M.

2008-12-01

249

Sea ice biogeochemistry: a guide for modellers.  

PubMed

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

Tedesco, Letizia; Vichi, Marcello

2014-01-01

250

Future regional Arctic sea ice declines  

NASA Astrophysics Data System (ADS)

Because animals and humans respond to seasonally and regionally varying climates, it is instructive to assess how much confidence we can have in regional projections of sea ice from the 20 models provided through the International Panel on Climate Change Fourth Assessment Report (AR4) process (IPCC 2007). Based on the selection of a subset models that closely simulate observed regional ice concentrations for 1979-1999, we find considerable evidence for loss of sea ice area of greater than 40% by 2050 in summer for the marginal seas of the Arctic basin. This conclusion is supported by consistency in the selection of the same models across different regions, and the importance of thinning ice and increased open water at mid-century to the rate of ice loss. With less confidence, we find that the Bering, Okhotsk and Barents Seas have a similar 40% loss of sea ice area by 2050 in winter. Baffin Bay/Labrador shows little change compared to current conditions. These seasonal ice zones have large interannual/decadal variability in addition to trends. Large model-to-model differences were seen for the Kara/Laptev Seas and East Greenland. With a careful evaluation process, AR4 sea ice projections have some utility for use in assessing potential impacts over large Arctic subregions for a 2020-2050 time horizon.

Overland, James E.; Wang, Muyin

2007-09-01

251

Mycosporine-like amino acids in Antarctic sea ice algae, and their response to UVB radiation.  

PubMed

Mycosporine like amino acids (MAAs) were detected in low concentration in sea ice algae growing in situ at Cape Evans, Antarctica. Four areas of sea ice were covered with plastics of different UV absorption exposing the bottom- ice algal community to a range of UV doses for a period of 15 days. Algae were exposed to visible radiation only; visible + UV radiation; and visible + enhanced UV radiation. MAA content per cell at the start of the experiment was low in snow-covered plots but higher in samples from ice with no snow cover. During the study period, the MAA content per cell reduced in all treatments, but the rate of this decline was less under both ambient UV and visible radiation than under snow covered plots. While low doses of UVB radiation may have stimulated some MAA production (or at least slowed its loss), relatively high doses of UVB radiation resulted in almost complete loss of MAAs from ice algal cells. Despite this reduction in MAA content per cell, the diatoms in all samples grew well, and there was no discernible effect on viability. This suggests that MAAs may play a minor role as photoprotectants in sea ice algae. The unique structure of the bottom ice algal community may provide a self-shading effect such that algal cells closest to the surface of the ice contain more MAAs than those below them and confer a degree of protection on the community as a whole. PMID:12132687

Ryan, Ken G; McMinn, Andrew; Mitchell, Kevin A; Trenerry, Louise

2002-01-01

252

The role of sea ice in the temperature-precipitation feedback of glacial cycles  

NASA Astrophysics Data System (ADS)

The response of the hydrological cycle to climate variability and change is a critical open question, where model reliability is still unsatisfactory, yet upon which past climate history can shed some light. Sea ice is a key player in the climate system and in the hydrological cycle, due to its strong albedo effect and its insulating effect on local evaporation and air-sea heat flux. Using an atmospheric general circulation model with specified sea surface temperature and sea-ice distribution, the role of sea ice in the hydrological cycle is investigated under last glacial maximum (LGM) and present day conditions, and by studying its contribution to the "temperature-precipitation feedback". By conducting a set of sensitivity experiments in which the albedo and thickness of the sea ice are varied, the various effects of sea ice in the hydrological cycle are isolated. It is demonstrated that for a cold LGM like state, a warmer climate (as a result of reduced sea-ice cover) leads to an increase in snow precipitation over the ice sheets. The insulating effect of the sea ice on the hydrological cycle is found to be larger than the albedo effect. These two effects interact in a nonlinear way and their total effect is not equal to summing their separate contribution.

Gildor, Hezi; Ashkenazy, Yosef; Tziperman, Eli; Lev, Ilit

2014-08-01

253

Ice Sheet and Sea Ice Observations from Unmanned Aircraft Systems  

NASA Astrophysics Data System (ADS)

A suite of sensors has been assembled to map ice sheet and sea ice surface topography with fine-resolution from small unmanned aircraft systems (UAS). This payload is optimized to provide coincident surface elevation and imagery data, and with its low cost and ease of reproduction, it has the potential to become a widely-distributed observational resource to complement polar manned-aircraft and satellite missions. To date, it has been deployed to map ice sheet elevations near Jakobshavn Isbræ in Greenland, and to measure sea ice freeboard and roughness in Fram Strait off the coast of Svalbard. Data collected during these campaigns have facilitate a detailed assessment of the system's surface elevation measurement accuracy, and provide a glimpse of the summer 2009 Fram Strait sea ice conditions. These findings are presented, along with a brief overview of our future Arctic UAS operations.

Crocker, R. I.; Maslanik, J. A.

2011-12-01

254

Geostatistical Relationships Between Freeboard and Thickness of Antarctic Sea Ice Floes Derived from Terrestrial LiDAR Surveys  

NASA Astrophysics Data System (ADS)

Sea ice is a critical component of the Earth's climate system and is a highly complex media. The physical characteristics are important in interpretation of remote sensing data. Sea ice characteristics such as snow surface topography, snow depth and ice thickness were derived from in situ measurements obtained during the J.C. Ross (ICEBell) and Oden Southern Ocean (OSO) expeditions during the austral summer of 2010-11. Select areas of sea ice floes in the Bellingshausen, Weddell and Amundsen Seas were measured using terrestrial scanning LiDAR (TSL) and also by conventional gridded and transect surveys. Snow depths were obtained at 2-5 meter sampling intervals and ice thickness was estimated by both electromagnetic induction (EMI) and auger drilling at 2-5 meter intervals. The LiDAR data is gridded to a 10cm rasterized data set. The field data from multiple floes in different regions provide a unique three dimensional perspective of sea ice elevation, snow depth and derived freeboard. These floes are visualized in both space and spectral domains and analyzed using classic statistical and geostatistical methods to assess surface roughness, snow depth, and the effects of differing scales on data resolution. The correlation lengths needed for isostatic equilibrium of freeboard were determined. These relationships are useful in assessing radar and laser altimetry data from airborne and satellite sources.

Lewis, M. J.; Parra, J.; Weissling, B.; Ackley, S. F.; Maksym, T. L.; Wilkinson, J.; Wagner, T.

2011-12-01

255

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

256

Satellite Remote Sensing: Passive-Microwave Measurements of Sea Ice  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

257

Recent variations of sea ice and air temperature in high latitudes  

SciTech Connect

Feedbacks resulting from the retreat of sea ice and snow contribute to the polar amplification of the greenhouse warming projected by global climate models. A gridded sea-ice database, for which the record length is now approaching four decades for the Arctic and two decades for the Antarctic, is summarized here. The sea-ice fluctuations derived from the data set are characterized by (1) temporal scales of several seasons to several years and (2) spatial scales of 30[degrees]-180[degrees] of longitude. The ice data are examined in conjunction with air temperature data for evidence of recent climate change in the polar regions. The arctic sea-ice variations over the past several decades are compatible with the corresponding air temperatures, which show a distinct warming that is strongest over northern land areas during the winter and spring. The temperature trends over the sub arctic seas are smaller and even negative in the southern Greenland region. Statistically significant decreases of the summer extent of arctic ice are apparent in the sea-ice data, and new summer minima have been achieved three times in the past 15 years. There is no significant trend of ice extent in the Arctic during winter or in the Antarctic during any season. The seasonal and geographical changes of sea-ice coverage are consistent with the more recent greenhouse experiments performed with coupled atmosphere-ocean models.

Chapman, W.L.; Walsh, J.E. (Univ. of Illinois, Urbana (United States))

1993-01-01

258

Climate, Ocean, and Sea Ice Modeling Project  

NSDL National Science Digital Library

This site provides an overview of the Climate, Ocean and Sea Ice Modeling Project (COSIM) and its mission to develop sea ice and ocean models which can be applied to coupled climate models. Research areas include polar processes, thermohaline circulation, ocean biogeochemistry, and eddy resolving ocean simulations. Available models include the Parallel Ocean Program (POP), the Los Alamos Sea Ice Model, and eventually the hybrid vertical coordinate version of POP. In addition, COSIM researchers have provided substantial input and development to the Miami Isopycnal Coordinate Ocean Model and its hybrid vertical coordinate equivalent Hybrid Coordinate Ocean Model. Links to these model pages contain model downloads, documentation and data.

Laboratory, Los A.

259

Modeling Landfast Sea Ice by Adding Tensile Strength  

Microsoft Academic Search

Landfast ice is sea ice that forms and remains fixed along a coast, where it is attached either to the shore or held between shoals or grounded icebergs. The current generation of sea ice models is not capable of reproducing certain aspects of landfast ice behavior, for example the persistence of landfast sea ice under the effect of offshore winds.

CHRISTOF KONIG BEATTY; DAVID M. HOLLAND

2009-01-01

260

Photophysiology and cellular composition of sea ice algae  

Microsoft Academic Search

The productivity of sea ice algae depends on their physiological capabilities and the environmental conditions within various microhabitats. Pack ice is the dominant form of sea ice, but the photosynthetic activity of associated algae has rarely been studied. Biomass and photosynthetic rates of ice algae of the Weddell-Scotia Sea were investigated during autumn and winter, the period when ice cover

Lizotte

1989-01-01

261

L-band radiometry for sea ice applications  

NASA Astrophysics Data System (ADS)

Although sea ice remote sensing has reached the level of operational exploitation with well established retrieval methods, several important tasks are still unsolved. In particular during freezing and melting periods with mixed ice and water surfaces, estimates of ice concentration with passive and active microwave sensors remain challenging. Newly formed thin ice is also hard to distinguish from open water with radiometers for frequencies above 8 GHz. The SMOS configuration (planned launch 2009) with a radiometer at 1.4 GHz is a promising technique to complement observations at higher microwave frequencies. ESA has initiated a project to investigate the possibilities for an additional Level-2 sea ice data product based on SMOS. In detail, the project objectives are (1) to model the L band emission of sea ice, and to assess the potential (2) to retrieve sea ice parameters, especially concentration and thickness, and (3) to use cold water regions for an external calibration of SMOS. Modelling of L band emission: Several models have are investigated. All of them work on the same basic principles and have a vertically-layered, plane-parallel geometry. They are comprised of three basic components: (1) effective permittivities are calculated for each layer based on ice bulk and micro-structural properties; (2) these are integrated across the total depth to derive emitted brightness temperature; (3) scattering terms can also be added because of the granular structure of ice and snow. MEMLS (Microwave Emission Model of Layered Snowpacks (Wiesmann and Matzler 1999)) is one such model that contains all three elements in a single Matlab program. In the absence of knowledge about the internal structure of the sea ice, three-layer (air, ice and water) dielectric slab models which take as input a single effective permittivity for the ice layer are appropriate. By ignoring scattering effects one can derive a simple analytic expression for a dielectric slab as shown by Apinis and Peake (1976). This expression was used by Menashi et al. (1993) to derive the thickness of sea ice from UHF (0.6 GHz) radiometer. Second, retrieval algorithms for sea ice parameters with emphasis on ice-water discrimination from L-band observations considering the specific SMOS observations modes and geometries are investigated. A modified Menashi model with the permittivity depending on brine volume and temperature suggests a thickness sensitivity of up to 150 cm for low salinity (multi year or brackish) sea ice at low temperatures. At temperatures approaching the melting point the thickness sensitivity reduces to a few centimetres. For first year ice the modelled thickness sensitivity is roughly half a meter. Runs of the model MEMLS with input data generated from a 1-d thermodynamic sea ice model lead to similar conclusio. The results of the forward model may strongly vary with the input microphysical details. E.g. if the permittivity is modelled to depend in addition on the sea ice thickness as supported by several former field campaigns for thin ice, the model predictions change strongly. Prior to the launch of SMOS, an important source of observational data is the SMOS Sea-Ice campaign held near Kokkola, Finland, March 2007 conducted as an add-on of the POL-ICE campaign. Co-incident L-band observations taken with the EMIRAD instrument of the Technical University of Denmark, ice thickness values determined from the EM bird of AWI and in situ observations during the campaign are combined. Although the campaign data are to be use with care, for selected parts of the flights the sea ice thickness can be retrieved correctly. However, as the instrumental conditions and calibration were not optimal, more in situ data, preferably from the Arctic, will be needed before drawing clear conclusions about a future the sea ice thickness product based on SMOS data. Use of additional information from other microwave sensors like AMSR-E might be needed to constrain the conditions, e.g. on sea ice concentration and temperature. External calibration: to combine SMOS ice info

Heygster, G.; Hedricks, S.; Mills, P.; Kaleschke, L.; Stammer, D.; Tonboe, R.

2009-04-01

262

Tertiary ice sheet dynamics: The snow gun hypothesis  

SciTech Connect

The authors abserve strong negative correlation between Tertiary low- to mid-latitude planktonic foraminiferal {delta}{sup 18}O and the difference between these data and coeval benthic foraminiferal {delta}{sup 18}O. Late Quaternary data do not show this correlation. Coupling statistical model/{delta}{sup 18}O comparisons and evidence for Antarctic ice and ocean temperature variation, they infer that Tertiary ice volume, recorded by tropical planktonic {delta}{sup 18}O became lost in the noise. This renders low correlation between Teritiary planktonic and benthic {delta}{sup 18}O time series compared to late Quaternary data. They contend that Tertiary ice sheet growth was commonly driven by warming of deep water from low- to mid-latitude, cooled. Because tectonic forcing and orbital forcing at low-latitude primarily controlled production and temperature variations of this Warm Saline Deep Water, these influences largely dictated Tertiary ice volume fluctuations. Through the Tertiary, they infer ice volume fluctuations to be an important component of sea level history on timescales between 10{sup 3} and 10{sup 7} years.

Prentice, M.L. (Univ. of Maine, Orono (USA)); Matthews, R.K. (Brown Univ., Providence, RI (USA))

1991-04-10

263

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

264

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

NASA Technical Reports Server (NTRS)

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.

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

265

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

E-print Network

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

Heaton, Thomas H.

266

The anisotropic scattering coefficient of sea ice  

NASA Astrophysics Data System (ADS)

transfer in sea ice is subject to anisotropic, multiple scattering. The impact of anisotropy on the light field under sea ice was found to be substantial and has been quantified. In this study, a large data set of irradiance and radiance measurements under sea ice has been acquired with a Remotely Operated Vehicle (ROV) in the central Arctic. Measurements are interpreted in the context of numerical radiative transfer calculations, laboratory experiments, and microstructure analysis. The ratio of synchronous measurements of transmitted irradiance to radiance shows a clear deviation from an isotropic under-ice light field. We find that the angular radiance distribution under sea ice is more downward directed than expected for an isotropic light field. This effect can be attributed to the anisotropic scattering coefficient within sea ice. Assuming an isotropic radiance distribution under sea ice leads to significant errors in light-field modeling and the interpretation of radiation measurements. Quantification of the light field geometry is crucial for correct conversion of radiance data acquired by Autonomous Underwater Vehicles (AUVs) and ROVs.

Katlein, Christian; Nicolaus, Marcel; Petrich, Chris

2014-02-01

267

Mapping of sea ice production for Antarctic coastal polynyas  

Microsoft Academic Search

Active sea-ice production in Antarctic coastal polynyas causes dense water formation, finally leading to Antarctic Bottom Water (AABW) formation. This study gives the first mapping of sea ice production in the Antarctic Ocean, based on heat-flux calculation with ice thickness data derived from satellite data. The highest ice production occurs in the Ross Ice Shelf Polynya region. The ice production

Takeshi Tamura; Kay I. Ohshima; Sohey Nihashi

2008-01-01

268

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

269

Measuring the sea ice floe size distribution  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

270

Comparison Graph of Sea Ice Minimum - 2010  

NASA Video Gallery

This animated graph tracks the retreat of sea ice, measured in millions of square kilometers, averaged from the start of the satellite record in 1979 through 2000 (white). Next, the graph follows t...

271

Sea Ice Thickness Comparison: 1979 vs 2013  

NASA Video Gallery

This animation compares the difference in the area, volume and depth of the average September Arctic sea ice between 1979, shown in blue, and 2013, shown in orange. The data from these two years ha...

272

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

E-print Network

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

Feltham, Daniel

273

Short Term Variability of Sea Ice Thickness in the Beaufort Sea  

Microsoft Academic Search

To investigate the relationship between variability of sea ice thickness and ice dynamics, helicopter borne electromagnetic sea ice thickness sounding was performed at the APLIS ice camp in the Beaufort sea in April 2007. The field campaign includes sea ice thickness observations close to the camp with repeated flight tracks of different length scales and a transect ranging from 75°N

S. Hendricks; J. Hutchings

2007-01-01

274

Floating Ice-Algal Aggregates below Melting Arctic Sea Ice  

PubMed Central

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

Assmy, Philipp; Ehn, Jens K.; Fernandez-Mendez, 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

275

Salt release from warming sea ice  

Microsoft Academic Search

In a field study in the Arctic, ejection of dense, saline plumes was observed 1 m below warm land-fast first-year sea ice, under conditions where the heat balance at the ice-ocean interface predicted melting. We describe the observed momentum, heat and salt fluxes in the boundary layer under the ice and the structure of the plume events. Measured downward salt

Karolina Widell; Ilker Fer; Peter M. Haugan

2006-01-01

276

Arctic sea ice decline: Faster than forecast  

Microsoft Academic Search

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

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

2007-01-01

277

ARKTOS: An intelligent system for SAR sea ice image classification  

E-print Network

We present an intelligent system for satellite sea ice image analysis named Advanced Reasoning using Knowledge for T ping Of Sea ice (ARKTOS). ARKTOS performs fully automated analysis of synthetic aperture radar (SAR) sea ...

Soh, L. K.; Tsatsoulis, Costas; Gineris, D.; Bertoia, C.

2004-01-01

278

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

NASA Astrophysics Data System (ADS)

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.

Sato, Kazutoshi; Inoue, Jun; Watanabe, Masahiro

2014-05-01

279

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

E-print Network

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

Massachusetts at Amherst, University of

280

Impact of underwater-ice evolution on Arctic summer sea ice  

E-print Network

Impact of underwater-ice evolution on Arctic summer sea ice Dirk Notz,1,4 Miles G. McPhee,2 M. Grae to make predictions of bottom ablation rates of sea ice given the far-field properties of the ocean from-lasting sea ice and thus smaller ice-free areas, which might be an important mechanism affecting the surface

Worster, M. Grae

281

Small antennas for communication over sea ice  

NASA Astrophysics Data System (ADS)

The invention described herein relates to an antenna system which makes use of the waveguide properties of sea ice. The antenna system broadly includes at least one antenna wire extending along and preferably in contact with a sea ice surface for transmitting and receiving substantially vertically polarized radio waves. In a first embodiment, the antenna system has a single antenna wire connected to a tuner at one end and grounded to seawater at a second end. The antenna system also has a second length of wire attached to the tuner. The second wire passes through a hole in the sea ice and is also grounded to the seawater beneath the sea ice. In an alternative embodiment, only the second wire is grounded to the seawater beneath the sea ice. The single antenna wire in this embodiment is ungrounded. In yet another embodiment, the antenna system comprises a dipole antenna wire laying on the surface of the sea ice and being connected to a radio for transmitting and receiving radio signals.

Mileski, Paul

1993-10-01

282

Effects of Arctic Sea Ice Decline on Weather and Climate: A Review  

NASA Astrophysics Data System (ADS)

The areal extent, concentration and thickness of sea ice in the Arctic Ocean and adjacent seas have strongly decreased during the recent decades, but cold, snow-rich winters have been common over mid-latitude land areas since 2005. A review is presented on studies addressing the local and remote effects of the sea ice decline on weather and climate. It is evident that the reduction in sea ice cover has increased the heat flux from the ocean to atmosphere in autumn and early winter. This has locally increased air temperature, moisture, and cloud cover and reduced the static stability in the lower troposphere. Several studies based on observations, atmospheric reanalyses, and model experiments suggest that the sea ice decline, together with increased snow cover in Eurasia, favours circulation patterns resembling the negative phase of the North Atlantic Oscillation and Arctic Oscillation. The suggested large-scale pressure patterns include a high over Eurasia, which favours cold winters in Europe and northeastern Eurasia. A high over the western and a low over the eastern North America have also been suggested, favouring advection of Arctic air masses to North America. Mid-latitude winter weather is, however, affected by several other factors, which generate a large inter-annual variability and often mask the effects of sea ice decline. In addition, the small sample of years with a large sea ice loss makes it difficult to distinguish the effects directly attributable to sea ice conditions. Several studies suggest that, with advancing global warming, cold winters in mid-latitude continents will no longer be common during the second half of the twenty-first century. Recent studies have also suggested causal links between the sea ice decline and summer precipitation in Europe, the Mediterranean, and East Asia.

Vihma, Timo

2014-09-01

283

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

E-print Network

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

Laidre, Kristin L.

284

Local-scale Snow Accumulation Variability On The Greenland Ice Sheet From Ground penetrating Radar (GPR)  

Microsoft Academic Search

Measurements of snow accumulation are critical to studies of mass balance. Traditional point measurement techniques (snow pits, manual probes, firn and ice cores) are limited in space and often do not represent the region surrounding them due to spatial variability that is caused by a variety of factors, including surface slope and deposition and erosion by wind. Current accumulation maps

J. Maurer; K. Steffen

2007-01-01

285

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

EPA Science Inventory

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

286

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

E-print Network

that snow accumulation on a GPS antenna produces significant positioning biases [Webb et al., 1995; Jahldehag et al., 1996]. This was expected because snow and ice are conducting media and affect in a way that contami- nates the carrier phase data. This leads in turn to a positioning bias. Later, even

Larson, Kristine

287

NASA's sea ice program: present and future  

E-print Network

, and the rising trend, 200508, is associated with a cyclonic advance of salty Atlanticderived water. Declining, and L. Stock (2008), Accelerated decline in the Arctic sea ice cover, Geophy. Res. Lett. 35, L01703, doi 2003 2005 2007 2009 Year Area(103km2) Kwok (2008) Jan -1 fields MY fraction Decline in multiyear sea

Kuligowski, Bob

288

Preservation of glaciochemical time-series in snow and ice from the Penny Ice Cap, Baffin Island  

Microsoft Academic Search

A detailed investigation of major ion concentrations of snow and ice in the summit region of Penny Ice Cap (PIC) was performed to determine the effects of summer melt on the glaciochemical time-series. While ion migration due to meltwater percolation makes it difficult to confidently count annual layers in the glaciochemical profiles, time-series of these parameters do show good structure

Nancy S. Grumet; Cameron P. Wake; Greg A. Zielinski; David Fisher; Roy Koerner; John D. Jacobs

1998-01-01

289

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

SciTech Connect

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.

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

290

Understanding changes in the Arctic basin sea ice mass budget as simulated by CCSM4: Implications from melt season characteristics and the surface albedo feedback  

Microsoft Academic Search

Observations reveal alarming drops in Arctic sea ice extent, and climate models project that further changes will occur that could have global repercussions. An important aspect of this change is the surface albedo feedback, driven by the contrast between the albedos of snow\\/ice and the open ocean. In response to warming, this feedback enhances ice melt and amplifies surface warming

D. A. Pollak; M. M. Holland; D. A. Bailey

2010-01-01

291

Snow precipitation at four ice core sites in East Antarctica: provenance, seasonality and blocking factors  

NASA Astrophysics Data System (ADS)

Snow precipitation is the primary mass input to the Antarctic ice sheet and is one of the most direct climatic indicators, with important implications for paleoclimatic reconstruction from ice cores. Provenance of precipitation and the dynamic conditions that force these precipitation events at four deep ice core sites (Dome C, Law Dome, Talos Dome, and Taylor Dome) in East Antarctica were analysed with air mass back trajectories calculated using the Lagrangian model and the mean composite data for precipitation, geopotential height and wind speed field data from the European Centre for Medium Range Weather Forecast from 1980 to 2001. On an annual basis, back trajectories showed that the Atlantic-Indian and Ross-Pacific Oceans were the main provenances of precipitation in Wilkes Land (80%) and Victoria Land (40%), respectively, whereas the greatest influence of the ice sheet was on the interior near the Vostok site (80%) and in the Southwest Ross Sea (50%), an effect that decreased towards the coast and along the Antarctic slope. Victoria Land received snowfall atypically with respect to other Antarctica areas in terms of pathway (eastern instead of western), seasonality (summer instead of winter) and velocity (old air age). Geopotential height patterns at 500 hPa at low (>10 days) and high (2-6 days) frequencies during snowfall cycles at two core sites showed large positive anomalies at low frequencies developing in the Tasman Sea-Eastern Indian Ocean at higher latitudes (60-70°S) than normal. This could be considered part of an atmospheric blocking event, with transient eddies acting to decelerate westerlies in a split region area and accelerate the flow on the flanks of the low-frequency positive anomalies.

Scarchilli, Claudio; Frezzotti, Massimo; Ruti, Paolo Michele

2011-11-01

292

Massive phytoplankton blooms under Arctic sea ice.  

PubMed

Phytoplankton blooms over Arctic Ocean continental shelves are thought to be restricted to waters free of sea ice. Here, we document a massive phytoplankton bloom beneath fully consolidated pack ice far from the ice edge in the Chukchi Sea, where light transmission has increased in recent decades because of thinning ice cover and proliferation of melt ponds. The bloom was characterized by high diatom biomass and rates of growth and primary production. Evidence suggests that under-ice phytoplankton blooms may be more widespread over nutrient-rich Arctic continental shelves and that satellite-based estimates of annual primary production in these waters may be underestimated by up to 10-fold. PMID:22678359

Arrigo, Kevin R; Perovich, Donald K; Pickart, Robert S; Brown, Zachary W; van Dijken, Gert L; Lowry, Kate E; Mills, Matthew M; Palmer, Molly A; Balch, William M; Bahr, Frank; Bates, Nicholas R; Benitez-Nelson, Claudia; Bowler, Bruce; Brownlee, Emily; Ehn, Jens K; Frey, Karen E; Garley, Rebecca; Laney, Samuel R; Lubelczyk, Laura; Mathis, Jeremy; Matsuoka, Atsushi; Mitchell, B Greg; Moore, G W K; Ortega-Retuerta, Eva; Pal, Sharmila; Polashenski, Chris M; Reynolds, Rick A; Schieber, Brian; Sosik, Heidi M; Stephens, Michael; Swift, James H

2012-06-15

293

Active microwave measurements of artificial sea ice  

NASA Technical Reports Server (NTRS)

A 5 m x 15 m outdoor tank of 1.2 m depth was filled with sea water, and polarimetric radar backscatter data were collected at 1.8, 5, and 10 GHz for incidence angles 0 to 60 deg. Observations commenced with open water and continued until 30 cm of sea ice formed. The roughness of the ice surface is important in determining the general backscatter level for first-year ice. Experiments were performed to study the change in backscatter with various roughness scales. Effects of freeze and thaw conditions were also examined. Absolute backscatter levels for new to gray ice are small, except for the large, coherent returns at vertical. The backscatter responses of new, gray, rough grey, and desalinated first-year ice at linear polarization are dissimilar. This is confirmed by examining their polarization signatures.

Onstott, R. G.; Gaboury, S. H.; Bredow, J.; Gogineni, P.

1988-01-01

294

Void bounds for fluid transport properties of sea ice  

Microsoft Academic Search

Arctic and Antarctic sea ice plays a critical role in the global oceanclimate system, as well as in polar biology. Sea ice is a porous composite of pure ice with brine and air inclusions whose microstructure varies significantly with temperature. The fluid transport properties of sea ice control a broad range of geophysical and biological processes. Yet little is known,

K. M. Golden; A. L. Heaton; H. Eicken; V. I. Lytle

2005-01-01

295

Modelling Sea Ice Growth Mark J. McGuinness  

E-print Network

Modelling Sea Ice Growth Mark J. McGuinness Received Day December 2007; revised Day Month Year flux, and slowing ice growth. 1 Introduction The temperature at which sea-water freezes depends on its #12;When cold air causes open sea-water to begin to freeze, many small ice crystals (frazil ice) form

McGuinness, Mark

296

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

297

A sea ice model for the marginal ice zone with an application to the Greenland Sea  

Microsoft Academic Search

A model is presented that describes the formation, transport, and desalinization of frazil and pancake ice as it is formed in marginal seas. This model uses as input the total ice concentration evaluated from Special Sensor Microwave Imager and wind speed and direction. The model calculates the areal concentration, thickness, volume concentration, and salinity of frazil ice as well as

Leif Toudal Pedersen; Max D. Coon

2004-01-01

298

Satellite-based estimates of sea-ice volume flux through Fram Strait  

NASA Astrophysics Data System (ADS)

Sea-ice volume fluxes through Fram Strait, Arctic Ocean, are estimated for the two ICESat measurement periods in February/March and October/November 2003 by combining sea-ice area fluxes, determined from space-borne microwave observations, with estimates of the sea-ice thickness distribution, inferred from measurements of ICESat's Geoscience Laser Altimeter System (GLAS) instrument. The thickness is derived from ICESat data by converting its surface elevation measurements into an ice freeboard estimate. Combined with prior information about ice density and snow depth and density, the freeboard is converted into ice thickness. Uncertainties in freeboard estimates due to geoid model errors are reduced through the use of the recent geoid from the Arctic Gravity Project. Missing information about the ocean circulation and ocean tides is approximated locally by interpolating the sea surface height linearly between open leads. Meridional ice volume fluxes estimated for 79° N using ice drift observed by AMSR-E (QuikSCAT) amount to 168 km3 (236 km3) and 62 km3 (77 km3) for 30 day periods in February/March and October/November 2003, respectively. These values lie in the range of previous results from similar studies, but are considerably smaller than the average ice flux during the 1990s, most likely because of a smaller ice-drift speed during 2003.

Spreen, Gunnar; Kern, Stefan; Stammer, Detlef; Forsberg, Rene; Haarpaintner, Jörg

299

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

300

Decadal to seasonal variability of Arctic sea ice albedo  

E-print Network

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...

Agarwal, S; Wettlaufer, J S

2011-01-01

301

Fram Strait sea ice outflow  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

302

Sea Ice Response to Wind Forcing from AMIP Models  

Microsoft Academic Search

The Arctic surface circulation simulated by atmospheric general circulation models is assessed in the context of driving sea ice motion. A sea ice model is forced by geostrophic winds from eight models participating in the first Atmospheric Model Intercomparison Project (AMIP1), and the results are compared to simulations with the sea ice model forced by observed winds. The mean sea

C. M. Bitz; John C. Fyfe; Gregory M. Flato

2002-01-01

303

The Secret of the Svalbard Sea Ice Barrier  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

304

Laser Altimetry Sampling Strategies over Sea Ice  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

305

Towards a new generation sea ice model  

NASA Astrophysics Data System (ADS)

A new sea ice model is being developed in view of reproducing sea ice dynamics at all spatial and temporal scales. This model uses a new elasto-brittle rheology. We will present preliminary results showing the capability of this model at simulating various types of dynamical behavior, whether it is in the central Arctic, in marginal seas, or near the ice edge. This model reproduces the statistical properties of the sea ice drift and deformation as shown by satellite observations, and naturally exhibits the large scale anisotropy of the deformation field. Based on the results of a high-resolution simulation, we will show the impacts of the simulated sea ice dynamics on the concentration and thickness fields for a period of several weeks over the Arctic basin. More specifically, we will focus on the high frequency opening and closing of leads, which will be likely to have large impacts on brines rejections and the upper Arctic Ocean mixing once our model will be coupled to an ocean model.

Rampal, Pierre; Bouillon, Sylvain

2014-05-01

306

How to Calculate Sea Ice Changes  

NSDL National Science Digital Library

This set of three videos illustrates how math is used in satellite data analysis. The videos feature NASA senior climate scientist Claire Parkinson. Parkinson explains how the Arctic and Antarctic sea ice covers are measured from satellite data and how math is used to determine trends in the data. In the first video, she leads viewers from satellite data collection through obtaining a time series of monthly average sea ice extents for November 1978 â December 2012, for the Arctic and Antarctic. In the second video, she begins with the time series from the first video, removes the seasonal cycle by calculating yearly averages, and proceeds to calculate the slopes of the lines to get trends in the data, revealing decreasing sea ice coverage in the Arctic and increasing sea ice coverage in the Antarctic. In the third video, she uses a more advanced technique to remove the seasonal cycle and shows that the trends are close to the same, whichever method is used. She emphasizes the power of math and that the techniques shown for satellite sea ice data can also be applied to a wide range of data sets.

307

Rate and state sea ice friction  

NASA Astrophysics Data System (ADS)

The distribution of ice thicknesses in the Arctic is a function of the ice deformation which occurs through ridging, rafting and sliding of ice floes. To determine the relative importance of each of these forms of deformation, it is crucial to have a good model of ice friction. We present data on ice-ice friction from a series of large ice-tank experiments, undertaken at the HSVA ship testing facility in Hamburg, Germany. We focus on the impact of varying the sliding rate, and the hold-time before commencing sliding, following the work of Ruina (1983). We move a 2m square floating ice block, of thickness 25cm, under horizontal normal stress, and detail the force required to move the block and hence the implied friction coefficient ?. Loads are of the order 1kN. We find that the time-averaged friction coefficient shows slight rate-dependence, and ? = 0.3-0.4 for a variety of rates (from 1-10cm/s). However, the detailed sliding mechanism varies with rate, and stick-slip behaviour is observed at low rates. The state-dependence is found to be a crucial factor in determining the load required to initiate movement of the ice block. To test for state dependence we apply the side load for a given time interval (the hold time) before starting to move the block. With a hold time of 1000s, the forces are an order of magnitude greater than with a hold time of 10s, and we present data for hold times from 1- 1000s. This work has important implications for sea ice rheology components within global climate models, particularly given that recent satellite observations show that almost all the deformation of Arctic sea ice is due to in-plane frictional sliding. The results outlined above suggest that the static contact time between ice floes may be the key parameter influencing the ensemble movement of sea ice. The work also has value for smaller-scale modelling of sea ice for engineering purposes, for example in predicting forces on offshore structures. As well as presenting our results, we will discuss possible further experiments to extend the range of validity of the work.

Lishman, B.; Sammonds, P.

2009-04-01

308

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

NASA Astrophysics Data System (ADS)

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.

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

309

Neogene History of Antarctic Sea-ice and Development of the Sea-ice Diatom Community  

NASA Astrophysics Data System (ADS)

Sea-ice plays an important role in the modern Antarctic climate system and in this region's linkage to lower latitude regions. Today, the seasonal sea-ice cover decouples oceanic heat transfer to the atmosphere, which amplifies winter's low temperatures and shifts sources of moisture far to the north. The sea-ice zone is an important site for biological productivity and bottom water formation, through cooling and brine exclusion. The absence of the sea-ice during past and future periods of elevated temperatures would significantly impact the biology, oceanography, glaciology and meteorology of the Antarctic region. A unique diatom assemblage is adapted to life in and around the sea-ice, and serves as an increasingly useful proxy to mark the presence, extent and duration of sea-ice cover. This assemblage dominates Antarctic shelf sediments today and back through most of the Quaternary. The oldest fossil diatom flora with a similar composition and structure to that of the modern sea-ice community was identified in a late Miocene mudstone erratic MB-244C in coastal moraine from McMurdo Sound. This assemblage did not persist through to the present day, and it is absent, or significantly reduced, in numerous marine diatom-bearing strata of late Miocene, Pliocene and Quaternary age, including the upper Miocene McLeod Beds of the Battye Glacier Formation, Prince Charles Mountains, the lower Pliocene Sorsdal Formation in the Vestfold Hills, the Pliocene sediments from the DVDP and CIROS drillcores, and the lower Quaternary carbonate unit in the Cape Roberts Project drillcore CRP-1. The sea-ice diatom community likely persisted in low numbers in interior fjords and basins, adjacent to glacier margins during these times. The history of sea-ice development and fluctuation during the Neogene appears to be complex, with substantial variability in sea-ice cover. Core records are currently insufficient to document the details of this history, and variation in the diatom assemblages through times of climate transition, but potential is high to utilize the diatom record as a proxy indicator for sea-ice cover. Sea-ice likely existed in Antarctic waters prior to the late Miocene, and morphological analyses of species within several diatom genera recovered in the erratic sample may provide a means of extending sea-ice interpretations back in time.

Harwood, D. M.; Bohaty, S. M.; Whitehead, J. M.

2002-12-01

310

A review of sea ice proxy information from polar ice cores  

NASA Astrophysics Data System (ADS)

Sea ice plays an important role in Earth's climate system. The lack of direct indications of past sea ice coverage, however, means that there is limited knowledge of the sensitivity and rate at which sea ice dynamics are involved in amplifying climate changes. As such, there is a need to develop new proxy records for reconstructing past sea ice conditions. Here we review the advances that have been made in using chemical tracers preserved in ice cores to determine past changes in sea ice cover around Antarctica. Ice core records of sea salt concentration show promise for revealing patterns of sea ice extent particularly over glacial-interglacial time scales. In the coldest climates, however, the sea salt signal appears to lose sensitivity and further work is required to determine how this proxy can be developed into a quantitative sea ice indicator. Methane sulphonic acid (MSA) in near-coastal ice cores has been used to reconstruct quantified changes and interannual variability in sea ice extent over shorter time scales spanning the last ˜160 years, and has potential to be extended to produce records of Antarctic sea ice changes throughout the Holocene. However the MSA ice core proxy also requires careful site assessment and interpretation alongside other palaeoclimate indicators to ensure reconstructions are not biased by non-sea ice factors, and we summarise some recommended strategies for the further development of sea ice histories from ice core MSA. For both proxies the limited information about the production and transfer of chemical markers from the sea ice zone to the Antarctic ice sheets remains an issue that requires further multidisciplinary study. Despite some exploratory and statistical work, the application of either proxy as an indicator of sea ice change in the Arctic also remains largely unknown. As information about these new ice core proxies builds, so too does the potential to develop a more comprehensive understanding of past changes in sea ice and its role in both long and short-term climate changes.

Abram, Nerilie J.; Wolff, Eric W.; Curran, Mark A. J.

2013-11-01

311

Massive variability in 1960's maximum Antarctic Sea ice extent from Nimbus satellite data  

NASA Astrophysics Data System (ADS)

An analysis of visible imagery from Nimbus observations provides an accurate assessment of the sea ice extent in the Arctic and Antarctic before the microwave satellite era. Previously we reported that the sea ice extent for 1964 was higher than current climatology around Antarctica in September 1964 and within the range of climatology in the Arctic for 1964. We now have results for summer 1966, which show substantially low ice extent around Antarctica. During the same period the Nimbus Arctic observations appear to coincide with the historic record. Typical values of maximum sea ice around Antarctica are between 17 and 18 X 106 km2 from the microwave satellite record. The Nimbus 1 1964 estimate is 19.6 X 106 km2 and Nimbus 2 1966 is 15.2 X 106 km2. The Antarctic deviations from the standard climatology are much larger than the year to year variations over the last 20 years (3 sigma events). By the presentation we will have estimates from Nimbus 3 in the summer of 1969. Most important we can put error bars on the monthly average estimates. In the arctic we can compare the results to sea ice charts. The raw satellite imagery data will be available from the National Snow and Ice Data Center and we will describe the way to access it as well as the detailed ice edge maps. Sea Ice around Antarctica

Campbell, G.; Gallaher, D. W.; Meier, W.

2012-12-01

312

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

E-print Network

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

Kuligowski, Bob

313

Clues to Variability in Arctic Minimum Sea Ice Extent  

E-print Network

of the variation in winter ice extent in the Bering Sea, Barents Sea, and Sea of Okhotsk, but oceanographic forcing of these three points directly southward to the coast was recorded as a time series, except in the Barents Sea

Francis, Jennifer

314

Fungal spores as potential ice nuclei in fog\\/cloud water and snow  

Microsoft Academic Search

INTRODUCTION: In discussions about climate change and precipitation frequency biological ice nucleation has become an issue. While bacterial ice nucleation (IN) is already well characterized and even utilized in industrial processes such as the production of artificial snow or to improve freezing processes in food industry, less is known about the IN potential of fungal spores which are also ubiquitous

Heidi Bauer; Fabio L. T. Goncalves; Elisabeth Schueller; Hans Puxbaum

2010-01-01

315

The occurrence of lead in Antarctic recent snow, firn deposited over the last two centuries and prehistoric ice  

NASA Astrophysics Data System (ADS)

Concentrations of lead have been measured by ultraclean Isotope Dilution Mass Spectrometry in snow cores covering the last two centuries collected at an inland site in East Antarctica using an ultra clean all plastic hand operated auger and in a prehistoric blue ice block collected at an Antarctic coastal site. Lead contamination of 16 to 200 pg Pb/g existed on the outside of the snow cores, but the measured concentrations decreased more or less abruptly along a radius from the outside to the centers of the snow cores, establishing interior values in the 1 to 5 pg Pb/g range. Some of these interior values are however possibly still slightly affected by lead contamination which could have intruded to the center of the cores because of slight melting of some of the snow cores before laboratory analysis. The interior of the blue ice block appears not to have been significantly contaminated, and contains about 1.7 pg Pb/g. These new data show that most previously published data on lead in Antarctic snow and ice were in high positive error because of contamination during field sampling, laboratory analysis or both. They show that lead concentrations could not have increased in Antarctic snows or ice from prehistoric times to present more than 2 to 3 fold, confirming that the remote polar areas of the Southern Hemisphere are still little affected by industrial lead pollution. Prehistoric Antarctic ice is shown to contain about 1 pg Pb/g natural excess lead above silicate dust lead; this excess cannot be entirely accounted for by volcanoes or sea spray, which suggests the possible existence of some other unknown natural source of prehistoric excess lead. Present day mean eolian fallout flux of lead in Antarctica is estimated to be about 0.07 ng Pb cm -2 yr -1, which stands in about the same proportion to that in the South Pacific Westerlies (about 1:30) as the flux in Greenland is observed to stand to those in the North Pacific and North Atlantic Westerlies.

Boutron, Claude F.; Patterson, Clair C.

1983-08-01

316

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

NASA Astrophysics Data System (ADS)

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.

Leitzell, K.; Meier, W.

2010-12-01

317

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

318

Fram Strait sea ice outflow  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

319

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

320

Productivity of Microalgae in Antarctic Sea Ice.  

PubMed

Midsummer productivity of Antarctic microalgae, commonly occurring in brown sea ice along the west coast of the Palmer Peninsula, averaged more than 900 milligrams of carbon per cubic meter per hour, with an assimilation number of about 2.6. The rate of photosynthesis increased with light intensity to a maximum of about 18,000 lux, above which some inhibition was observed. The floral composition, genesis, and physiological properties of these ice communities are different from the epontic under-ice diatoms previously studied by other investigators in McMurdo Sound. PMID:17737387

Burkholder, P R; Mandelli, E F

1965-08-20

321

Energy and ozone fluxes over sea ice  

NASA Astrophysics Data System (ADS)

We present surface layer measurements made over Hudson Bay sea ice during February/March 2008 from the COBRA (Impact of combined iodine and bromine release on the Arctic atmosphere) experiment which formed part of the International OASIS (Ocean-Atmosphere-Sea Ice-Snowpack) IPY programme. All components of the local surface energy balance were measured and it was defined by net radiative cooling throughout most of the day, mainly balanced by the conductive heat flux from the warmer sea water to the cooler sea ice at the surface, and a small net radiative warming for a few hours after midday. Unique ground-level ozone fluxes were measured by eddy covariance and deposition velocities ranged from +0.5 mm s -1 (deposition) to -1.5 mm s -1 (emission). Ozone profile measurements suggested ozone flux divergence within the surface layer. The observed bi-directional fluxes and flux divergence with height reveal the complexity of surface ozone fluxes in the Arctic spring time surface layer, and show that ozone exchange with the sea ice surface is best probed using the eddy covariance method alongside frequent or continuous profile measurements. In this study, the local in-situ ozone-halogen photochemistry was identified as weakly controlling the measured ozone flux, whereas horizontal advection and vertical mixing were considered more important in influencing fluxes. Under these conditions, several measurement sites would be desirable in order to quantify the contribution of advection to the local surface exchange.

Muller, Jennifer B. A.; Dorsey, James R.; Flynn, Michael; Gallagher, Martin W.; Percival, Carl J.; Shallcross, Dudley E.; Archibald, Alexander; Roscoe, Howard K.; Obbard, Rachel W.; Atkinson, Helen M.; Lee, James D.; Moller, Sarah J.; Carpenter, Lucy J.

2012-02-01

322

Will Arctic sea ice thickness initialization improve seasonal forecast skill?  

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

323

Comparative Views of Arctic Sea Ice Growth  

NASA Technical Reports Server (NTRS)

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

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

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

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

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

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

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

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

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

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

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

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

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

2000-01-01

324

Early inventory of black carbon particulate size in accumulated snow and ice  

NASA Astrophysics Data System (ADS)

Although size distributions of black carbon (BC) aerosol in the ambient atmosphere have become increasingly available in recent years, in snow and ice it is nearly unexplored. Here, we follow up on first measurements of the size distribution of refractory black carbon (BC) particulate in snow that showed that BC in snow can lie in a larger size range than is typically observed in the ambient atmosphere. This observation has implications for BC light absorption in the cryosphere, as well as for the processes that govern BC removal from the atmosphere by snow and BC aging on the surface. Snow samples from the American and Canadian Mid-West and Greenland, and ice core samples from the Cascades, were stored as sampled without additional thaw/free cycles until they were analyzed in the laboratory with a single particle soot photometer/Collison nebulizer setup. Although many samples were too clean (~<1 ng-BC/g-H2O) to allow measurement of high-quality BC size distributions, we were able to assess BC size in some snow samples and in presumed forest-fire emission layers captured in ice cores. Our results provide first constraints on the range and variability of the BC mass size distribution in the cryosphere, and on possible implications for the BC mass absorption cross section and role of BC in reduction of snow albedo.

Schwarz, J. P.; Gao, R.; Perring, A. E.; Markovic, M. Z.; Doherty, S. J.; Polashenski, C.; Kaspari, S.; Dibb, J. E.; Scheuer, E. M.; Fahey, D. W.

2013-12-01

325

Snow precipitation at four ice core sites in East Antarctica: provenance, seasonality and blocking factors  

Microsoft Academic Search

Snow precipitation is the primary mass input to the Antarctic ice sheet and is one of the most direct climatic indicators,\\u000a with important implications for paleoclimatic reconstruction from ice cores. Provenance of precipitation and the dynamic conditions\\u000a that force these precipitation events at four deep ice core sites (Dome C, Law Dome, Talos Dome, and Taylor Dome) in East\\u000a Antarctica

Claudio Scarchilli; Massimo Frezzotti; Paolo Michele Ruti

326

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

327

Sea ice thickness measurements - data management considerations  

NASA Astrophysics Data System (ADS)

IPY is in full swing with numerous ice stations, voyages, and autonomous systems. Thickness is a key variable being measured intensively during this period to assess the mass balance of sea ice and its rate of change under increasingly warming conditions. Within this context, quantification of sea ice thickness variability at a multiple of scales is being investigated and recorded in both hemispheres by scores of scientists from around the globe. While this measured variability will lead to new understanding of sea ice and its relationship to the global climate, variability in data structures used to record and archive these results will only lead to inconsistencies, incompatibilities, and a lack of spatiotemporal coherence. The sea ice community (small and adaptable as it is) needs to develop a consensus of critical thickness parameters and associated meta data criterion that can profit from two main sources of data gathering: operations (which usually produce high data volume with minimal analysis) and science projects (offering low data volume, but considerable analysis). Consensus between the operational and science community on key data and meta data requirements will make the difference in both the quality and volume of a long-term sea ice thickness archive. This presentation explores ways to address these issues by considering a fundamental set of protocol/format requirements when recording thickness measurements. In particular, records of the sampling rates and spatial scales, instrument type and uncertainties, etc. Essentially, we need to develop and follow a standard format for archiving sea ice thickness measurements. This does not mean "ASCII" or "CSV", rather a clearly defined parameter set which covers major scales, procedures, and algorithms used to define thickness and associated uncertainties. Efforts on this topic can be used to spearhead a white paper to circulate throughout the community to build a common set of protocols for archiving sea ice thickness from the drilled point measurement to the satellite footprint. We present this topic to stimulate discussion within both operational and research communities on how best to proceed.

Geiger, C.; Fetterer, F.; Meier, W.

2007-12-01

328

A numerical study of open water formation in sea ice  

Microsoft Academic Search

A multicategory sea ice model that explicitly takes into account redistribution of undeformed ice into categories of ridged and rafted ice is introduced with the intention of investigating the simulation of the open water fraction within sea ice. The performance of this model is compared with that of a reduced model that accounts for only two categories, the latter type

J. Haapala; N. Lönnroth; A. Stössel

2005-01-01

329

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

330

POLAR SEA ICE MAPPING FOR SEAWINDS Hyrum S. Anderson  

E-print Network

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

Long, David G.

331

POLAR SEA-ICE CLASSIFICATION USING ENHANCED RESOLUTION NSCAT DATA  

E-print Network

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

Long, David G.

332

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

E-print Network

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

Lindsay, Ron

333

Ice and ocean processes in the Bellingshausen Sea, Antarctica  

Microsoft Academic Search

In the vicinity of the Antarctic Peninsula observations show diminishing sea ice and a rapid warming of atmosphere and ocean. These changes have led to the collapse of ice shelves and retreat, acceleration, and thinning of inland ice. However, ocean observations in the center of the nearby Bellingshausen Sea are spatially and temporally coarse. In this study, ocean and sea

Paul R. Holland; Adrian Jenkins; David M. Holland

2010-01-01

334

Assessing Arctic Sea Ice Thickness using Wavelets Don Percival  

E-print Network

Assessing Arctic Sea Ice Thickness using Wavelets Don Percival Applied Physics Laboratory://faculty.washington.edu/dbp/talks.html 1 #12;Overview · thickness of Arctic sea ice is subject of ongoing scientific interest · seminar changes providing additional insights into Arctic sea ice variability · work in progress with Yanling Yu

Percival, Don

335

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

USGS Publications Warehouse

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

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

2010-01-01

336

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

NASA Astrophysics Data System (ADS)

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.

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

337

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

NASA Astrophysics Data System (ADS)

Knowledge of sea ice is critical to the hunting, whaling, and cultural activities of many Indigenous communities in Northern and Western Alaska. Experienced hunters have monitored seasonal changes of the sea ice over many years, giving them a unique expertise in assessing the current state of the sea ice as well as any anomalies in seasonal sea ice conditions. The Seasonal Ice Zone Observing Network (SIZONet), in collaboration with the Exchange for Local Observations and Knowledge of the Arctic (ELOKA), has developed an online application for collecting, storing, and analyzing sea ice observations contributed by local experts from coastal Alaskan communities. Here we present the current iteration of the application, outline future plans and discuss how the development process and resulting system have improved our collective understanding of sea ice processes and changes. The SIZONet application design is based on the needs of the research scientists responsible for entering observation data into the database, the needs of local sea ice experts contributing their observations and knowledge, and the information needs of Alaska coastal communities. Entry forms provide a variety of input methods, including menus, check boxes, and free text input. Input options strive to balance flexibility in capturing concepts and details with the need for analytical consistency. Currently, research staff at the University of Alaska Fairbanks use the application to enter observations received via written or electronic communications from local sea ice experts. Observation data include current weather conditions, snow and ice quantity and quality, and wildlife sighted or taken. Future plans call for direct use of the SIZONet interface by local sea ice experts as well as students, both as contributors to the data collection and as users seeking meaning in the data. This functionality is currently available to a limited number of community members as we extend the application to support specific roles for particular users (or groups of users); this role-based access will be necessary to support a diverse user population while maintaining the integrity of the data and protecting personal information, or the location of sensitive sites, captured in the data records. Additionally, future improvements to the interface will include the ability to upload photos and videos to capture visual records of the environment. The SIZONet application was developed to provide a robust interface for working with observational data. The contributed nature of the data, however, presents a unique set of collaborative benefits and challenges as we work towards the final implementation of the application. The successful partnership supporting the observation network is a direct function of the long-term relationships established between university-based researchers and community members.

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

2012-12-01

338

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

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

339

What About Sea Ice? People, animals, and climate change in the polar regions: An online resource for the International Polar Year and beyond  

NASA Astrophysics Data System (ADS)

Decreasing Arctic sea ice has been one of the most noticeable changes on Earth over the past quarter-century. The years 2002 through 2005 have had much lower summer sea ice extents than the long-term (1979-2000). Reduced sea ice extent has a direct impact on Arctic wildlife and people, as well as ramifications for regional and global climate. Students, educators, and the general public want and need to have a better understanding of sea ice. Most of us are unfamiliar with sea ice: what it is, where it occurs, and how it affects global climate. The upcoming International Polar Year will provide an opportunity for the public to learn about sea ice. Here, we provide an overview of sea ice, the changes that the sea ice is undergoing, and information about the relation between sea ice and climate. The information presented here is condensed from the National Snow and Ice Data Center's new 'All About Sea Ice' Web site (http://www.nsidc.org/seaice/), a comprehensive resource of information for sea ice.

Renfrow, S.; Meier, W. N.; Wolfe, J.; Scott, D.; Leon, A.; Weaver, R.

2005-12-01

340

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...

2008-12-29

341

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...

2008-12-29

342

ORIGINAL PAPER A bacterial ice-binding protein from the Vostok ice core  

E-print Network

Bacterial and yeast isolates recovered from a deep Antarctic ice core were screened for proteins with ice found in sea ice diatoms, a snow mold, and a sea ice bacterium. The protein has the ability to inhibit Introduction The Vostok Ice Core represents a cross-section of the East Antarctic Ice Sheet to a depth of over

Christner, Brent C.

343

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

Microsoft Academic Search

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,

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

2007-01-01

344

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

345

Snow Facies Over Ice Sheets Derived From Envisat Active and Passive Observations  

Microsoft Academic Search

This paper aims to separate different snow regions over the terrestrial ice sheets based on their measured microwave signatures. It takes advantage of coregistered data from passive and active sensors on the Environmental Satellite (Envisat) to directly derive a snow facies indicator in a point-by-point basis. This paper represents the first attempt of this kind in exploiting nadir-viewing and dual-frequency

Ngan Tran; Frédérique Rémy; Hui Feng; Pierre Féménias

2008-01-01

346

On producing sea ice deformation dataset from SAR-derived sea ice motion  

NASA Astrophysics Data System (ADS)

We propose a method to compute nearly noise-free sea ice deformation fields from SAR-derived motion and present the results of its application to RGPS sea ice trajectories. 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. 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 multi-fractal analysis. 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.

Bouillon, S.; Rampal, P.

2014-10-01

347

Global Warming and Changes in Sea Ice in the Greenland Sea: 1979-2007  

Microsoft Academic Search

Abstract This paper presents a statistical analysis of sea ice in the Greenland Sea (70-80N and 10W-10E) from January 1979 to December 2007. We define four variables from satellite images: ice extent, ice area, eastward ice extent at 75N, and the shape of the ice edge. We establish relationships between these ice variables and five climate variables: sea surface temperature

Maxine von Eye

348

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

NASA Astrophysics Data System (ADS)

derived from continuously operating GPS sites are used throughout the world for geophysical research. These positions are estimated assuming that the GPS signals have not been obstructed by either snow or ice on the GPS antenna. Unfortunately, in many regions of the world, this assumption is not correct. Snow and ice attenuate and scatter the GPS signal in a way that leads to significant positioning errors. These positioning outliers are typically removed by assuming geophysical models of displacement. In this study an algorithm is developed that uses signal strength data to determine when the GPS signal has been impacted by snow or ice. This information is then used to remove outliers in GPS coordinate time series. The signal strength-based algorithm was tested on 6 years of data from the EarthScope Plate Boundary Observatory network. The algorithm improves the precision of ~10% of these coordinate time series, with most of the improvement found for sites operating in Alaska.

Larson, Kristine M.

2013-08-01

349

Antarctic sea ice and temperature variations  

SciTech Connect

Monthly antarctic station temperatures are used in conjunction with grids of sea ice coverage in order to evaluate temporal trends and the strength of associations between the two variables at lags of up to several seasons. The trends of temperature are predominantly positive in winter and summer, but predominantly negative in spring. The spatially aggregated trend of temperature is small but positive, while the corresponding trend of ice coverage is small but negative. Cross-correlations between concurrent anomalies of the two variables are negative over most of the continent and are strongest over the Antarctic Peninsula, especially in winter. In regions other than the Antarctic Peninsula, lag correlations between seasonal anomalies are generally stronger with ice lagging the summer temperatures and with ice leading the winter temperatures.

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

1992-03-01

350

Arctic Sea Ice Retreat in 2007 Follows Thinning Trend  

Microsoft Academic Search

The minimum of Arctic sea ice extent in the summer of 2007 was unprecedented in the historical record. A coupled ice-ocean model is used to determine the state of the ice and ocean over the past 29 yr to investigate the causes of this ice extent minimum within a historical perspective. It is found that even though the 2007 ice

R. W. LINDSAY; J. Z HANG; A. S CHWEIGER; M. S TEELE; H. STERN

2009-01-01

351

Arctic Sea Ice: Trends, Stability and Variability  

NASA Astrophysics Data System (ADS)

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

Moon, Woosok

352

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

Microsoft Academic Search

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

Hajo Eicken; Manfred A. Lange

1989-01-01

353

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 ...

354

Variability of Arctic Sea Ice as Determined from Satellite Observations  

NASA Technical Reports Server (NTRS)

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

Parkinson, Claire L.

1999-01-01

355

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

PubMed Central

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

2014-01-01

356

Observed Anomalous Atmospheric Circulation in Summers of Unusual Arctic Sea Ice Reduction  

NASA Astrophysics Data System (ADS)

This study presents the atmospheric patterns (circulation, precipitation and temperature) associated with changes in Arctic sea ice extent (SIE) in summertime. Significant features and dynamical linkages of the parameter fields are presented. Sea ice extent and concentration are from the National Snow & Ice Data Center (NSIDC), while sea level pressure, winds, temperature, radiation, precipitation and snowfall - used to characterize storms, cloud cover, warming/cooling effects, large-scale wave trains and jet streams - come from the European Re-Analysis Interim (ERA-Interim) re-analysis. The storm track characteristic is analyzed using the Kevin Hodges TRACK algorithm, based on zonal and meridional winds at 850 hPa. Significant patterns result from compositing anomalous high (+1 STD, 23 months) and low (-1 STD, 17 months) standardized SIE reduction months in summer (May-August, MJJA) over 1979-2013. For high SIE reduction months, a relative anticyclonic circulation over the Arctic Ocean emerges. Resulting is a tendency for storms to shun the Arctic Ocean, following a more zonal path, and hence contributing to a weakening of the climatological Arctic Ocean Cyclone Maximum. For the Arctic Ocean, a reduced cloud cover results in less precipitation, where the particular decrease in snowfall over sea ice in August lowers the albedo and hence increases the ice reduction. The warming over the continents increases the land-sea temperature contrast, resulting in increased cyclogenesis especially along the Siberian coast. In mid-latitudes, the shift in storm tracks results in an increase in storms and rainfall over northwestern Europe and southern Scandinavia. The presentation adds to the ongoing discussion on Arctic sea ice and mid-latitude extreme weather, and also contributes to the understanding of feedback mechanisms in the region. With the current declining trend in sea ice expected to continue in the coming decades, the understanding of anomalous circulation patterns associated to sea-ice loss is important for assessing changes in the Arctic climate system and their impacts.

Knudsen, Erlend; Orsolini, Yvan; Furevik, Tore; Hodges, Kevin

2014-05-01

357

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

Microsoft Academic Search

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

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

2005-01-01

358

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

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

359

Ensemble of sea ice initial conditions for interannual climate predictions  

NASA Astrophysics Data System (ADS)

Polar climate studies are severely hampered by the sparseness of the sea ice observations. We aim at filling this critical gap by producing two 5-member sea ice historical simulations strongly constrained by ocean and atmosphere observational data and covering the 1958-2006 and 1979-2012 periods. This is the first multi-member sea ice reconstruction covering more than 50 years. The obtained sea ice conditions are in reasonable agreement with the few available observations. These best estimates of sea ice conditions serve subsequently as initial sea ice conditions for a set of 28 3-year-long retrospective climate predictions. We compare it to a set in which the sea ice initial conditions are taken from a single-member sea ice historical simulation constrained by atmosphere observations only. We find an improved skill in predicting the Arctic sea ice area and Arctic near surface temperature but a slightly degraded skill in predicting the Antarctic sea ice area. We also obtain a larger spread between the members for the sea ice variables, thus more representative of the forecast error.

Guemas, Virginie; Doblas-Reyes, Francisco J.; Mogensen, Kristian; Keeley, Sarah; Tang, Yongming

2014-11-01

360

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

E-print Network

Seasonal variations in N and O isotopes of nitrate in snow at Summit, Greenland: Implications for the study of nitrate in snow and ice cores Meredith G. Hastings Department of Geosciences, Princeton, nitrate Citation: Hastings, M. G., E. J. Steig, and D. M. Sigman (2004), Seasonal variations in N and O

Sigman, Daniel M.

361

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

362

Towards an Ice-free Northern Sea Route?  

NASA Astrophysics Data System (ADS)

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.

Rodrigues, J. M.

2006-12-01

363

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

NASA Astrophysics Data System (ADS)

Melt pond formation is a common feature of the spring and summer Arctic sea ice. However, the role of the melt ponds formation and the impact of the sea ice melt on both the direction and size of CO2 flux between air and sea is still unknown. Here we describe the CO2-carbonate chemistry of melting sea ice, melt ponds and the underlying seawater associated with measurement of CO2 fluxes across first year landfast sea ice in the Resolute Passage, Nunavut, in June 2012. Early in the melt season, the increase of the ice temperature and the subsequent decrease of the 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. Later on, melt pond formation affects both the bulk sea ice and the brine system. As melt ponds are formed from melted snow the in situ melt pond pCO2 is low (36 ?atm). The percolation of this low pCO2 melt water into the sea ice matrix dilutes the brine resulting in a strong decrease of the in situ brine pCO2 (to 20 ?atm). As melt ponds reach equilibrium with the atmosphere, their in situ pCO2 increase (up to 380 ?atm) and the percolation of this high concentration pCO2 melt water increase the in situ brine pCO2 within the sea ice matrix. The low in situ pCO2 observed in brine and melt ponds results in CO2 fluxes of -0.04 to -5.4 mmol m-2 d-1. As melt ponds reach equilibrium with the atmosphere, the uptake becomes less significant. However, since melt ponds are continuously supplied by melt water their in situ pCO2 still remains low, promoting a continuous but moderate uptake of CO2 (~ -1mmol m-2 d-1). The potential uptake of atmospheric CO2 by melting sea ice during the Arctic summer has been estimated from 7 to 16 Tg of C ignoring the role of melt ponds. This additional uptake of CO2 associated to Arctic sea ice needs to be further explored and considered in the estimation of the Arctic Ocean's overall CO2 budget.

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

2014-05-01

364

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

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

365

Respiration and bacterial carbon dynamics in Arctic sea ice  

Microsoft Academic Search

Bacterial carbon demand, an important component of ecosystem dynamics in polar waters and sea ice, is a function of both bacterial\\u000a production (BP) and respiration (BR). BP has been found to be generally higher in sea ice than underlying waters, but rates\\u000a of BR and bacterial growth efficiency (BGE) are poorly characterized in sea ice. Using melted ice core incubations,

Dan Nguyen; Roxane Maranger

366

Space Radar Image of Weddell Sea Ice  

NASA Technical Reports Server (NTRS)

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.

1994-01-01

367

Proceedings of EARSeL-SIG-Workshop Land Ice and Snow, Dresden/FRG, June 16 17, 2000 EARSeL eProceedings No. 1 246  

E-print Network

Proceedings of EARSeL-SIG-Workshop Land Ice and Snow, Dresden/FRG, June 16 ­ 17, 2000 EARSeL e. In order to supplement existing monitoring techniques for snow and ice-covered regions, HRSC-A was used application of HRSC-A for the remote sensing of snow and ice, particularly in the context of climate

Oldenburg, Carl von Ossietzky Universität

368

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

PubMed

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

Juricke, Stephan; Jung, Thomas

2014-06-28

369

Retrieval of sea ice thickness distribution in the seasonal ice zone from airborne L-band SAR  

Microsoft Academic Search

Although satellite data are known to be useful for obtaining ice thickness distribution for perennial sea ice or in stable thin sea ice areas, their use in the seasonal sea ice zone (SIZ) is still unresolved. In this study, we approached the problem of ice thickness retrieval by using L?band Synthetic Aperture Radar (SAR). In the SIZ, ice thickness growth

T. Toyota; K. Nakamura; S. Uto; K. I. Ohshima; N. Ebuchi

2009-01-01

370

Ultraviolet radiation and its extinction in antarctic sea ice  

SciTech Connect

This paper reports on the attentuation of radiation in sea ice with special attention to UV radiation. Changes in stratospheric ozone result in changes in the UV radiation, much more biologically active when compared with the visible spectrum, and can have a large effect on life. In this area of the Antarctic sea, a significant fraction of phytoplankton lives under and in the sea ice. This paper discusses the extinction of radiation in sea ice. 7 refs., 3 figs.

Wendler, G.; Quakenbush, T. (Univ. of Alaska, Fairbanks, AK (United States))

1993-01-01

371

Effect of environmental variables on eukaryotic microbial community structure of land-fast Arctic sea ice.  

PubMed

Sea ice microbial community structure affects carbon and nutrient cycling in polar seas, but its susceptibility to changing environmental conditions is not well understood. We studied the eukaryotic microbial community in sea ice cores recovered near Point Barrow, AK in May 2006 by documenting the composition of the community in relation to vertical depth within the cores, as well as light availability (mainly as variable snow cover) and nutrient concentrations. We applied a combination of epifluorescence microscopy, denaturing gradient gel electrophoresis and clone libraries of a section of the 18S rRNA gene in order to compare the community structure of the major eukaryotic microbial phylotypes in the ice. We find that the community composition of the sea ice is more affected by the depth horizon in the ice than by light availability, although there are significant differences in the abundance of some groups between light regimes. Epifluorescence microscopy shows a shift from predominantly heterotrophic life styles in the upper ice to autotrophy prevailing in the bottom ice. This is supported by the statistical analysis of the similarity between the samples based on the denaturing gradient gel electrophoresis banding patterns, which shows a clear difference between upper and lower ice sections with respect to phylotypes and their proportional abundance. Clone libraries constructed using diatom-specific primers confirm the high diversity of diatoms in the sea ice, and support the microscopic counts. Evidence of protistan grazing upon diatoms was also found in lower sections of the core, with implications for carbon and nutrient recycling in the ice. PMID:20050870

Eddie, Brian; Juhl, Andrew; Krembs, Christopher; Baysinger, Charles; Neuer, Susanne

2010-03-01

372

SAC-D/Aquarius MWR sea ice concentration: first results and validation  

NASA Astrophysics Data System (ADS)

The National Space Agency of Argentina (CONAE) developed the SAC-D/Aquarius science mission (launched in June 2011), together with the National Aeronautics and Space Administration (NASA). One of the sensors on board the SAC-D is a MWR (Micro Wave Radiometer). This instrument is a three channel push broom microwave radiometer with 8 antenna beams per channel and two different incident angles (52° and 58°), that provides a measurement swath of approximately 380 Km. These channels provide 36.5 GHz dual horizontal and vertical polarized and 23.8 GHz horizontal polarized radiance measurements in an overlapping swath with the L-band Aquarius radiometer/scatterometer. Geophysical variables over marine surface, such as, columnar water vapor, wind speed, sea ice concentration, and rain rate are generated with the data comming from MWR. It is well recognized that sea ice is the most significant characteristic of the polar ocean environment and influences the Earth's global climate. Some approaches such as the Bootstrap and the NASA Team algorithms have been designed to estimate sea ice concentration and type using microwave emissions. These algorithms rely primarily on the factor that polarization and spectrum are different for sea ice and open ocean. CONAE developed an algorithm with the collaboration of CFRSL (Central Florida Remote Sensing Laboratory) and SHN (Argentine Naval Hydrographic Service), for the sea ice concentration using data coming from MWR radiometer. This algorithm is based on differences between brightness temperatures corresponding to vertical and horizontal polarization of 36.5 GHz band and the gradient corresponding to values of 36.5 and 23.8 GHZ in horizontal polarization. A validation process was implemented with the collaboration of SHN researchers, using the sea ice concentration obtained from National Snow and Ice Data Center (NSIDC) for comparisons. In this work we present the first results of Sea Ice Concentration obtained using the CONAE algorithm for both, north and south poles. In addition, we show the preliminary validation analysis of those estimations.

Barreira, S.; Tauro, C. B.; Masuelli, S.; Salgado, H.; Jones, L.

2012-12-01

373

Antarctic Sea Ice Variability and Trends, 1979-2010  

NASA Technical Reports Server (NTRS)

In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978 - December 2010 reveal an overall positive trend in ice extents of 17,100 +/- 2,300 square km/yr. Much of the increase, at 13,700 +/- 1,500 square km/yr, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has, like the Arctic, instead experienced significant sea ice decreases, with an overall ice extent trend of -8,200 +/- 1,200 square km/yr. When examined through the annual cycle over the 32-year period 1979-2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9,100 +/- 6,300 square km/yr in February to a high of 24,700 +/- 10,000 square km/yr in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month,