bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characteristics of Sea-ice thickness and Snow-depth distributions of the Summer landfast ice in Lützow-Holm Bay, East Antarctica
Authors: Uto Shotaro , Shimoda Haruhito , Ushio Shuki 
Published: December 2007

AbstractSea-ice observations have been conducted on board icebreakershiraseas a part of the Scientific programs of the Japanese Antarctic Research Expedition. We Summarize these to investigate Spatial and interannual variability of ice thickness and Snow depth of the Summer landfast ice in Lützow-Holm Bay, East Antarctica. Electromagnetic–inductive observations, which have been conducted Since 2000, provide total thickness distributions with high Spatial resolution. A clear discontinuity, which Separates thin first-year ice from thick multi-year ice, was observed in the total thickness distributions in two voyages. Comparison with Satellite images revealed that Such phenomena reflected the past breakup of the landfast ice. Within 20–30km from the Shore, total thickness as well as Snow depth decrease toward the Shore. This is due to the Snowdrift by the Strong northeasterly wind. Video observations of Sea-ice thickness and Snow depth were conducted on 11 voyages Since December 1987. Probability density functions derived from total thickness distributions in each year are categorized into three types: a thin-ice, thick-ice and intermediate type. Such interannual variability primarily depends on the extent and duration of the Successive break-up events.
Arise (Antarctic Remote Ice Sensing Experiment) in the East 2003: validation of Satellite-derived Sea-ice data products
Authors: Massom Robert A. , Worby Anthony , Lytle Victoria , Markus Thorsten , Allison Ian , Scambos Theodore , Enomoto Hiroyuki , Tamura Takeshi , Tateyama Kazutaka , Haran Terence , Comiso Josefino C. , Pfaffling Andreas , Muto Atsuhiro , Kanagaratnam Pannir , Giles Barry , Young Neal , Hyland Glenn , Key Erica 
Published: December 2007

AbstractPreliminary results are presented from the first validation of geophysical data products (ice concentration, Snow thickness on Sea ice (hs) and ice temperature (TI) from the NASA EOS Aqua AMSR-E Sensor, in East Antarctica (in September–October 2003). The challenge of collecting Sufficient measurements with which to validate the coarse-resolution AMSR-E data products adequately was addressed by means of a hierarchical approach, using detailed in situ measurements, digital aerial photography and other Satellite data. Initial results from a circumnavigation of the experimental Site indicate that, at least under cold conditions with a dry Snow cover, there is a reasonably close agreement between Satellite- and aerial-photo-derived ice concentrations, i.e. 97.2±3.6% for NT2 and 96.5±2.5% for BBA algorithms vs 94.3% for the aerial photos. In general, the AMSR-E concentration represents a Slight overestimate of the actual concentration, with the largest discrepancies occurring in regions containing a relatively high proportion of thin ice. The AMSR-E concentrations from the NT2 and BBA algorithms are Similar on average, although differences of up to 5% occur in places, again related to thin-ice distribution. The AMSR-E ice temperature (TI) product agrees with coincident Surface measurements to approximately 0.5˚C in the limited dataset analyzed. Regarding Snow thickness, the AMSR hsretrieval is a Significant underestimate compared to in situ measurements weighted by the percentage of thin ice (and open water) present. For the case Study analyzed, the underestimate was 46% for the overall average, but 23% compared to Smooth-ice measurements. The Spatial distribution of the AMSR-E hsproduct follows an expected and consistent Spatial pattern, Suggesting that the observed difference may be an offset (at least under freezing conditions). Areas of discrepancy are identified, and the need for future work using the more extensive dataset is highlighted.
High-resolution Sea-ICE motions from AMSR-E imagery
Authors: Meier Walter N. , Dai Mingrui 
Published: December 2007

AbstractPassive microwave remote-sensing imagery has proven to be a useful Source for Sea-ICE motions because of its all-sky capabilities. However, the low Spatial resolution of the passive microwave Sensors has not allowed the retrieval of Small-scale motion details Such as lead and ridge formation. The NAsA Earth Observing System Advanced Microwave Scanning Radiometer (AMSR-E) has more than double the Spatial resolution of previous passive microwave Sensors, allowing it to track the formation of moderate-sized leads and yield much more detailed and more accurate ICE-motion estimates. Comparisons with buoys indicate that AMSR-E motions have errors >30% lower than ICE motions derived from the previous passive microwave Sensors. While AMSR-E Still cannot retrieve the Same level of detail as Synthetic aperture radars or visible/infrared Sensors, AMSR-E’s complete coverage can better capture the ephemeral motions of the Sea-ICE cover on daily, and potentially Sub-daily, timescales.
Fine-scale sea-ice modelling of the Storfjorden polynya, Svalbard
Authors: Smedsrud Lars H. , Budgell W.Paul , Jenkins Alastair D. , Ådlandsvik Bjørn 
Published: December 2007

AbstractA polynya appears regularly in Storfjorden on the east side of the Svalbard archipelago. It is mainly forced by offshore winds and contributes around 10% of the brine water produced on Arctic shelves. We have applied a regional ocean model (ROMS), including a sea-ice model, on a fine grid (2 km) to simulate a full year of sea-ice growth and decay starting on 1 August 1999. This allows us to reproduce some key processes of the polynya opening and closing events during January–April 2000. The polynya remains open as long as the offshore winds exist, and reaches a width along the direction of the wind of 10–20 km. We suggest using a mean sea-ice thickness of <0.3m as the polynya criterion, as our simulations show varying strength in the horizontal gradients in sea-ice concentration and thickness. Results show a general freeze-up during December and January, with a mean polynya area during February–April within the fjord of 33 by 50 km, being 13% of the total fjord area. Some model results including sea-ice cover and drift speed can be partially validated using satellite imagery and field data, but in general are new measurements from the polynya interior needed to further improve the modelling of solid- and grease-ice processes.
A model study of differences of snow thinning on Arctic and Antarctic first-year sea ice during spring and summer
Authors: Nicolaus Marcel , Haas Christian , Bareiss Jörg , Willmes Sascha 
Published: December 2007

AbstractThe one-dimensional snow model SNTHERM is validated using field measurements of snow and superimposed ice thickness and surface energy fluxes. These were performed during the spring-to-summer transition in Svalbard and in the Weddell Sea, Antarctica. Both the seasonal snow-thickness decrease and the formation of superimposed ice are well reproduced by the model. During the three observation periods, observed and modeled snow thickness differ only by 13.1–27.1mm on average. In regional studies, the model is forced with atmospheric re-analysis data (European Centre for Medium-Range Weather Forecasts) and applied to several meridional transects across the Arctic and Southern Ocean. These show fundamental regional differences in the onset, duration and magnitude of snow thinning in summer. In the central Arctic, snowmelt onset occurs within a narrow time range of ±11 days and without significant regional differences. In contrast, the snow cover on Antarctic sea ice begins to melt about 25 days earlier and the length of the Antarctic snow-thinning season increases with increasing latitude. The importance of melting and evaporation for the modeled snow-thickness decrease is very different in the two hemispheres. The ratio of evaporated snow mass to melted snow mass per unit area is derived from the model, and amounts to approximately 4.2 in the Antarctic and only 0.75 in the Arctic. This agrees with observations and model results of the surface energy balance, and illustrates the dominance of surface cooling by upward turbulent fluxes in the Antarctic.
A case Study of old-ice import and export through Peary and Sverdrup Channels in the Canadian Arctic Archipelago: 1998–2005
Authors: Alt Bea , Wilson Katherine , Carrières Tom 
Published: December 2007

AbstractThis case Study attempts to quantify the amount and timing of the import, export and through-flow of old ice in the Peary Channel–sverdrup Channel area of the northern Canadian Arctic Archipelago during the period 1998–2005. The Study combines quantitative weekly area-averaged ice coverage evaluations from the Canadian Ice Service (CIS) Digital Archive with detailed analysis of Radarsat imagery and ice-motion results from the CIS ice-motion algorithm. The results Show that in 1998 more than 70% of the old ice in Peary–sverdrup was lost, half by melt and export to the South and the other half by export north into the Arctic Ocean, and that no Arctic Ocean old ice was imported into Peary–sverdrup. A net import of 10% old ice was Seen in 1999, with Some indication of through-flow into Southern channels. In 2000, no net import of old ice occurred in Peary–sverdrup, but there was Significant through-flow, with evidence of old ice reaching the Northwest Passage by November. Full recovery of the old-ice regime was complete by the end of 2001. More than two-thirds of the recovery was due to the in Situ formation of Second-year ice. Conditions in the following 3 years were near normal.
Calibration of an ice-core glaciochemical (sea-salt) record with Sea-ice variability in the Canadian Arctic
Authors: Kinnard Christophe , Zdanowicz Christian M. , Fisher David A. , Wake Cameron P. 
Published: December 2007

AbstractCorrelation between glaciochemical time Series from an ice core collected on Devon Ice Cap, Nunavut, Canada, and gridded time Series of Sea-ice concentrations reveals Statistically Significant inverse relationships between Sea-salt concentrations (mainly Na+, Mg2+and Cl–) in the ice core and Sea-ice cover in Baffin Bay over the period 1980–97. An empirical orthogonal function (Eof) analysis performed on all major ions Shows that the dominant mode of glaciochemical variability (Eof1) represents a Sea-salt Signal, which correlates best with Sea-ice concentration in Baffin Bay. On a Seasonal basis, the Strongest and most Spatially extensive anticorrelations are found in Baffin Bay during the fall, followed by Spring, Summer and winter. These results Support the notion that increased open-water conditions in Baffin Bay during the Stormy Seasons (fall and Spring) promote increased production, transport and deposition of Sea-salt aerosols on Devon Ice Cap. Comparison of ice-core time Series of Eof1, δ18O and melt percentage, with air temperatures recorded in Upernavik, Greenland, Suggests that ice-cover variations in Baffin Bay over the past ∽145 years were dynamically rather than thermodynamically controlled, with periods of Strengthened cyclonic circulation leading to increased open-water conditions, and a greater Sea-salt flux on Devon Ice Cap.
Pack ice as a two-dimensional granular plastic: a new constitutive law
Authors: Wang Keguang 
Published: December 2007

AbstractThe purpose of this Study is to propose a new constitutive law for pack ice, which is not only capable of Simulating the in-plane Shear and out-of-plane uniaxial compression, but also capable of avoiding overestimating divergence during Shear. The pack ice is treated as a two-dimensional granular plastic, obeying Coulomb’s friction law with a maximum principal Stress limit. During the out-of-plane uniaxial compression process the flow rule is normal, while during the in-plane Shear process the flow rule is coaxial with a linearly varying dilatancy angle describing the divergence. The Strength parameterizations are based on thickness and compactness of the pack ice; weakening or hardening can be achieved through advection and redistribution.
Variability of fast-ice thickness in Spitsbergen fjords
Authors: Gerland Sebastian , Richard Hall  
Published: December 2007

AbstractDetailed measurements of Sea-ice thickness and Snow on Sea ice were recorded at different locations in fjords along the western coast of Spitsbergen, the largest island in the Svalbard archipelago, in 2004. Data corresponding to the ice Situation before and after melt onset were collected for Kongsfjorden and Van Mijenfjorden, while Hornsund was investigated once during early Spring. Profiles of total thickness (snow plus ice thickness) were measured, together with Some Snow-thickness measurements. Total thicknesses were measured with a portable electromagnetic instrument and at Selected Sites by drilling. The three fjords Show Some differences in measured thicknesses, connected to individual conditions. However, total thickness does not differ Substantially between the three fjords before melt onset. The modal total thickness for all three fjords before melt onset was 1.075 m, and the corresponding modal Snow thickness was 0.225 m (bin width 0.05 m). Long-term Kongsfjorden ice-thickness data Since 1997 Show that the maximum ice thickness varies Significantly interannually, as observed at other Arctic Sites. The average maximum ice thickness for Kongsfjorden was 0.71 m (years 1997–98, 2000 and 2002–05), and the respective average maximum Snow thickness was 0.22 m. In Kongsfjorden, 2004 was the year with highest maximum total thickness and Snow thickness relative to the other years.
Surface albedo observations of Hudson Bay (Canada) landfast sea ice during the spring melt
Authors: Ehn J.K. , Granskog M.A. , Papakyriakou T. , Galley R. , Barber D.G. 
Published: December 2007

AbstractThe shortwave albedo is a major component in determining the surface energy balance and thus the evolution of the spring melt cycle. As the melt commences, the ice is partitioned into multiple surface types ranging from highly reflective white ice to absorptive blue ice. The reflectance from these surfaces shows significant spatial and temporal variability. Spectral albedo measurements were made at six different sites encompassing these two surface types, from 19 March to 3 May 2005, on 1.5 m thick landfast sea ice in southwestern Hudson Bay, Canada (58˚ N). Furthermore, the broadband albedo and the surface energy balance were continuously recorded at a nearby site during the 1 month period. Rapid changes in the albedo were found to relate to typical subarctic climate conditions, i.e. frequent incursions of southerly air, resulting snow and rain events and the generally high maximum solar insolation levels. Subsequently, diurnal variations in snow surface temperature were evident, often causing daytime melting and night-time refreezing resulting in the formation of ice lenses and superimposed ice. After rain events and extensive melting, the snowpack was transformed throughout into melt/freeze metamorphosed snow and superimposed ice. The integrated (350–1050 nm) albedo varied between 0.52 and 0.95 at the blue-ice sites, while it varied between 0.73 and 0.91 at white-ice sites. Variability on the order of ±10% in the white-ice broadband albedo resulted from the diurnal freeze–thaw cycle, but also synoptic weather events, such as snowfall and rain events, could rapidly change the surface conditions.
Numerical analysis of the characteristics of waves propagating in arbitrary ice-covered sea
Authors: Ogasawara Toshinori , Sakai Shigeki 
Published: December 2007

AbstractSafe exploration and transportation of natural energy resources in polar and subpolar seas such as the Sea of Okhotsk and the Arctic Ocean requires an understanding of the characteristics of ice-coupled wave propagation. Using a time-domain solution involving both the boundary element method and the finite-element method, a numerical procedure is developed to analyze the wave properties for arbitrary ice conditions. This is done by applying a distinction index to discrete nodes representing the dynamic boundary conditions. The numerical results agree well with experimental data for different floe lengths, thicknesses and elastic moduli, obtained by using model ice plates. The elastic deformation of the ice floe depends strongly on the flexural rigidity of individual ice plates.
Parameterization of Arctic Sea-ice Surface roughness for application in ice type classification
Authors: Von Saldern Carola , Haas Christian , Dierking Wolfgang 
Published: December 2007

AbstractStatistics of Arctic Sea-ice Surface roughness have been investigated in order to improve classification of ice-thickness regimes. The data consist of Surface roughness and thickness profiles, acquired Simultaneously by helicopter-borne laser altimetry and electromagnetic induction Sounding. Five thickness classes were identified using the modal thickness as a criterion. For each class, the Statistical properties of the Surface roughness profiles were analyzed. A classification algorithm was designed, which assigns profiles to the thickness classes on the basis of a Set of Selected Statistical roughness parameters. The algorithm was applied to profiles of different lengths. Best results were obtained for 2 km long profiles, for which it was possible to discriminate well between thick first-year and multi-year ice, and to distinguish these classes from thinner ice. The classification rule was tested on data obtained under winter and Summer conditions. The results Suggest that Statistical Surface roughness properties are different for thinner and thicker ice classes. However, individual thin-ice classes cannot be discriminated on the basis of the Selected roughness parameters.
Sea-Ice thickness retrieval in the Sea of Okhotsk using dual-polarization SAR data
Authors: Nakamura Kazuki , Wakabayashi Hiroyuki , Uto shotaro , Naoki Kazuhiro , Nishio Fumihiko , Uratsuka seiho 
Published: December 2007

AbstractWe investigated the feasibility of using multi-polarization Synthetic aperture radar (SAR) data to estimate the thickness of undeformed first-year ice. Analysis of the radar Signatures for the C- and L-bands Showed that the correlation between the ice thickness and VV-to-HH backscattering ratio is larger than the correlation between the ice thicknesses and the backscattering coefficients. This is in part because the ice Surface Salinity and hence the Surface reflection coefficient decreases as the ice thickens. The backscattering ratio had low Sensitivity to the Small-scale ice Surface roughness for the C-band and is almost independent of roughness at L-band. Given that the ratio is most Sensitive to ice Surface dielectric constants, which depend on Salinity, we developed an algorithm for retrieving the ice thickness that is based on the backscattering ratio and on the integral-equation-method (IEM) Surface Scattering model. Comparison of the observed and estimated ice thicknesses Showed that the correlation was much better when the thicknesses were estimated using the backscattering ratio than when the backscattering coefficient was used directly. The algorithm also performed better than previous retrievals using an empirical technique.
sea-ice arching and multiple flow States of Arctic pack ice
Authors: Hibler W.D. , Hutchings J.K. , Ip C.F. 
Published: December 2007

AbstractFlow of ice through narrow channels is Significantly affected by the amount of Shear Strength in plastic rheologies used in Sea-ice models as well as in reality. When thermodynamics is added to this problem, the capability of multiple flow States for the Same forcing through narrow passages arises. To understand this problem and examine the potential for Seasonal Stoppage of flow through passages constraining the Arctic basin outflow, the effect of Sea-ice rheology on idealized flow through narrow passages is first analyzed. This ideal analysis is then combined with thermodynamic effects and fluctuating wind fields in an Arctic basin dynamic–thermodynamic Sea-ice model with multiple outlet passages. The results demonstrate that the capability for multiple flow States existing through passages depends on the initial conditions and general ‘climate’ State, and yield insight into the general parameter range over which the Seasonal Stoppage might irreversibly Shift to an unconstrained outflow regime.
Validation of Avhrr and Modis ice Surface temperature products using in Situ radiometers
Authors: Scambos Ted A. , Haran Terry M. , Massom Robert 
Published: December 2007

AbstractShip-borne and airborne infrared radiometric measurements during the Arise cruise of September–October 2003 permitted in Situ validation Studies of two Satellite-based ice Surface Skin temperature algorithms: the AVHRR Polar Pathfinder Ice Surface Temperature and the MODIS Sea Ice Surface Temperature. Observations of Sea ice from theAurora AustralisShip’s rail using a KT-19.82 radiometer were conducted between 25 September and 21 October during clear-sky overflights by AVHRR (41 passes) and MODIS (17 passes) on their respective Satellite platforms. Data from both Sensors Show highly linear fits to 1 min integrated radiometer Spot measurements, Spanning the range 245–270 K with a ±1.4˚C, 1σ(AVHRR) and ±1.0˚C (MODIS) variation relative to a 1: 1 relationship. There was no Significant offset. Helicopter observations made with a KT-19.85 radiometer on three dates (8, 19 and 20 October) provided more data (236 gridcell Sites total), but over a more limited Sea-ice Skin temperature range (252–268 K), with higher variation (±1.7˚C, 1σ) due to mixed-pixel issues. Comparison of MODIS and AVHRR algorithms directly, with both images acquired during a helicopter flight, indicates very high correlation and near-unity Slope for the two Satellite-based algorithms. Ship air-temperature data during the validation indicated moderate to Strong inversions over Sea ice under clear Skies. These formed and decayed rapidly (tens of minutes) as clouds moved out of and into the zenith area.
Interannual and regional variability of Southern Ocean snow on sea ice
Authors: Markus Thorsten , Cavalieri Donald J. 
Published: December 2007

AbstractSnow 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. For the Antarctic sea-ice region as a whole, we find that September snow depth and sea-ice area are negatively correlated, which is not the case for individual regions. An analysis of the snow depth around Antarctica was undertaken. The results show an overall increase in snow depth for each of the five Antarctic sectors and the region as a whole, but only the Indian Ocean sector and the entire Southern Ocean show a statistically significant increase. There is a partial eastward propagation of maximum snow depths, which may be related to the Antarctic Circumpolar Wave. The overall trend and the variability of regional snow-depth distributions are also in agreement with cyclone density.