scholarly journals Combined satellite- and ULS-derived sea-ice flux in the Weddell Sea, Antarctica

2001 ◽  
Vol 33 ◽  
pp. 125-132 ◽  
Author(s):  
Mark R. Drinkwater ◽  
Xiang Liu ◽  
Sabine Harms
Keyword(s):  
Fresh Water ◽  
Water Transport ◽  
Incidence Angle ◽  
Empirical Relationship ◽  
Rate Of Change ◽  
Weddell Sea ◽  
Ice Thickness ◽  
Volume Flux ◽  
Ice Volume ◽  
Flux Gate

AbstractSeveral years of daily microwave satellite ice drift are combined with moored upward-looking sonar (ULS) ice drafts into an ice-volume flux record at points along a flux gate across the Weddell Sea, Antarctica. Monthly ice transport varies at the mooring locations from a maximum export of 0.4 m3 s−1 near joinville Island to −0.4 m3 s−1 imported along the Fimbul and Riiser-Larsen ice-shelf margins. Winter peaks are observed at each end of the flux gate, where high concentrations of deformed ice are advected in and out of the basin along the coastline. The central gyre, in contrast, exhibits negligible seasonality and much smaller volume transports. During the period of overlapping ULS operation, the mean monthly integrated ice export west of the gyre center is 59 × 103 m3 s−1, and the import in the East Wind Drift is −17 x103 m3s-1. ULS data are compared with ERS satellite observation of radar backscatter to obtain an empirical relationship between ice thickness and the rate of change of backscatter with incidence angle. Resulting proxy ice-thickness data are combined with Special Sensor Microwave/Imager-derived ice velocities to obtain seasonally varying estimates of net ice-volume flux for the period 1992−98. Significant interannual variability is observed in ice-volume flux expressed as fresh-water transport. A maximum annual mean of 0.054 Sv is observed in 1992; with a minimum of 0.015 Sv in 1996. A 6 year mean transport of 0.032 Sv is observed. Maximum seasonal ice export occurs in July 1992, with a minimum in November 1996. The 10 year mean area flux is 30 × 103 m2s–1 Interannual variations in net volume flux closely follow variations in area flux, with summer minima in 1990/91 and 1996/97. Maximum area transport occurs in 1991, and although this predates the ERS-1 scatterometer data, ice-thickness estimates by Harms and others confirm 1991 as a decadal peak in net integrated fresh-water transport.

scholarly journals Modeling the Impact of Wind Intensification on Antarctic Sea Ice Volume

2014 ◽  
Vol 27 (1) ◽  
pp. 202-214 ◽  
Author(s):  
Jinlun Zhang
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Surface Wind ◽  
Ocean Model ◽  
Weddell Sea ◽  
Ice Thickness ◽  
Ice Volume ◽  
Antarctic Sea Ice ◽  
Ice Production ◽  
The Impact

Abstract A global sea ice–ocean model is used to examine the impact of wind intensification on Antarctic sea ice volume. Based on the NCEP–NCAR reanalysis data, there are increases in surface wind speed (0.13% yr−1) and convergence (0.66% yr−1) over the ice-covered areas of the Southern Ocean during the period 1979–2010. Driven by the intensifying winds, the model simulates an increase in sea ice speed, convergence, and shear deformation rate, which produces an increase in ridge ice production in the Southern Ocean (1.1% yr−1). The increased ridged ice production is mostly in the Weddell, Bellingshausen, Amundsen, and Ross Seas where an increase in wind convergence dominates. The increase in ridging production contributes to an increase in the volume of thick ice (thickness > 2 m) in the Southern Ocean, while the volumes of thin ice (thickness ≤ 1 m) and medium thick ice (1 m < thickness ≤ 2 m) remain unchanged over the period 1979–2010. The increase in thick ice leads to an increase in ice volume in the Southern Ocean, particularly in the southern Weddell Sea where a significant increase in ice concentration is observed. The simulated increase in either the thick ice volume (0.91% yr−1) or total ice volume (0.46% yr−1) is significantly greater than other ice parameters (simulated or observed) such as ice extent (0.14–0.21% yr−1) or ice area fraction (0.24%–0.28% yr−1), suggesting that ice volume is a potentially strong measure of change.

scholarly journals Ice thickness distribution of all Swiss glaciers based on extended ground-penetrating radar data and glaciological modeling

2021 ◽  
pp. 1-19
Author(s):  
Melchior Grab ◽  
Enrico Mattea ◽  
Andreas Bauder ◽  
Matthias Huss ◽  
Lasse Rabenstein ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Thickness Distribution ◽  
Radar Data ◽  
Tourism Industry ◽  
Swiss Alps ◽  
Ice Thickness ◽  
Hazard Management ◽  
Bed Topography ◽  
Ice Volume ◽  
Ground Penetrating

Abstract Accurate knowledge of the ice thickness distribution and glacier bed topography is essential for predicting dynamic glacier changes and the future developments of downstream hydrology, which are impacting the energy sector, tourism industry and natural hazard management. Using AIR-ETH, a new helicopter-borne ground-penetrating radar (GPR) platform, we measured the ice thickness of all large and most medium-sized glaciers in the Swiss Alps during the years 2016–20. Most of these had either never or only partially been surveyed before. With this new dataset, 251 glaciers – making up 81% of the glacierized area – are now covered by GPR surveys. For obtaining a comprehensive estimate of the overall glacier ice volume, ice thickness distribution and glacier bed topography, we combined this large amount of data with two independent modeling algorithms. This resulted in new maps of the glacier bed topography with unprecedented accuracy. The total glacier volume in the Swiss Alps was determined to be 58.7 ± 2.5 km3 in the year 2016. By projecting these results based on mass-balance data, we estimated a total ice volume of 52.9 ± 2.7 km3 for the year 2020. Data and modeling results are accessible in the form of the SwissGlacierThickness-R2020 data package.

scholarly journals Measuring and inferring the ice thickness distribution of four glaciers in the Tien Shan, Kyrgyzstan

2020 ◽  
pp. 1-18
Author(s):  
Lander Van Tricht ◽  
Philippe Huybrechts ◽  
Jonas Van Breedam ◽  
Johannes J. Fürst ◽  
Oleg Rybak ◽  
...  
Keyword(s):  
Cross Validation ◽  
Thickness Distribution ◽  
Tien Shan ◽  
Ice Thickness ◽  
Ice Volume ◽  
In Situ Data ◽  
Radio Echo Sounding ◽  
Thickness Measurements ◽  
Tien Shan Mountains

Abstract Glaciers in the Tien Shan mountains contribute considerably to the fresh water used for irrigation, households and energy supply in the dry lowland areas of Kyrgyzstan and its neighbouring countries. To date, reconstructions of the current ice volume and ice thickness distribution remain scarce, and accurate data are largely lacking at the local scale. Here, we present a detailed ice thickness distribution of Ashu-Tor, Bordu, Golubin and Kara-Batkak glaciers derived from radio-echo sounding measurements and modelling. All the ice thickness measurements are used to calibrate three individual models to estimate the ice thickness in inaccessible areas. A cross-validation between modelled and measured ice thickness for a subset of the data is performed to attribute a weight to every model and to assemble a final composite ice thickness distribution for every glacier. Results reveal the thickest ice on Ashu-Tor glacier with values up to 201 ± 12 m. The ice thickness measurements and distributions are also compared with estimates composed without the use of in situ data. These estimates approach the total ice volume well, but local ice thicknesses vary substantially.

scholarly journals Ice thickness and volume of the Renland Ice Cap, East Greenland

2021 ◽  
pp. 1-13
Author(s):  
Iben Koldtoft ◽  
Aslak Grinsted ◽  
Bo M. Vinther ◽  
Christine S. Hvidberg
Keyword(s):  
Surface Topography ◽  
Climate Model ◽  
Thickness Distribution ◽  
High Elevation ◽  
Surface Velocity ◽  
Ice Thickness ◽  
Model Parameters ◽  
East Greenland ◽  
Ice Volume ◽  
Ice Cap

Abstract To assess the amount of ice volume stored in glaciers or ice caps, a method to estimate ice thickness distribution is required for glaciers where no direct observations are available. In this study, we use an existing inverse method to estimate the bedrock topography and ice thickness of the Renland Ice Cap, East Greenland, using satellite-based observations of the surface topography. The inverse approach involves a procedure in which an ice dynamical model is used to build-up an ice cap in steady state with climate forcing from a regional climate model, and the bedrock is iteratively adjusted until the modelled and observed surface topography match. We validate our model results against information from airborne radar data and satellite observed surface velocity, and we find that the inferred ice thickness and thereby the stored total volume of the ice cap is sensitive to the assumed ice softness and basal slipperiness. The best basal model parameters for the Renland Ice Cap are determined and the best estimated total ice volume of 384 km3 is found. The Renland Ice Cap is particularly interesting because of its location at a high elevation plateau and hence assumed low sensitivity to climate change.

scholarly journals Janus Membrane with Novel Directional Water Transport Capacity for Efficient Atmospheric Water Capture

Nanoscale ◽  
2021 ◽  
Author(s):  
Jing Wu ◽  
Baona Ren ◽  
Haohong Pi ◽  
Xin Zhao ◽  
Miaomiao Hu ◽  
...  
Keyword(s):  
Fresh Water ◽  
Water Transport ◽  
Water Scarcity ◽  
Low Cost ◽  
Transport Capacity ◽  
Atmospheric Water ◽  
Human Survival ◽  
Survival And Development ◽  
Energy Independence

Fresh water scarcity becomes a crisis to human survival and development. Atmospheric water capture with remarkable advantages such as energy-independence, low-cost, etc., has been supposed as a promising way to...

scholarly journals A unifying framework for iceberg-calving models

2010 ◽  
Vol 56 (199) ◽  
pp. 822-830 ◽  
Author(s):  
Jason M. Amundson ◽  
Martin Truffer
Keyword(s):  
Empirical Relationship ◽  
Ice Thickness ◽  
Ice Shelf ◽  
Physical Explanation ◽  
Positive Feedbacks ◽  
First Order ◽  
External Forcings ◽  
Iceberg Calving ◽  
Calving Rate ◽  
Glacier Flow

AbstractWe propose a general framework for iceberg-calving models that can be applied to any calving margin. The framework is based on mass continuity, the assumption that calving rate and terminus velocity are not independent and the simple idea that terminus thickness following a calving event is larger than terminus thickness at the event onset. The theoretical, near steady-state analysis used to support and analyze the framework indicates that calving rate is governed, to first order, by ice thickness, thickness gradient, strain rate, mass-balance rate and backwards melting of the terminus; the analysis furthermore provides a physical explanation for a previously derived empirical relationship for ice-shelf calving (Alley and others, 2008). In the calving framework the pre- and post-calving terminus thicknesses are given by two unknown but related functions. The functions can vary independently of changes in glacier flow and geometry, and can therefore account for variations in calving behavior due to external forcings and/or self-sustaining calving processes (positive feedbacks). Although the calving framework does not constitute a complete calving model, any thickness-based calving criterion can easily be incorporated into the framework. The framework should be viewed as a guide for future attempts to parameterize calving.

scholarly journals ICESat observations of seasonal and interannual variations of sea-ice freeboard and estimated thickness in the Weddell Sea, Antarctica (2003–2009)

2011 ◽  
Vol 52 (57) ◽  
pp. 43-51 ◽  
Author(s):  
Donghui Yi ◽  
H. Jay Zwally ◽  
John W. Robbins
Keyword(s):  
Sea Ice ◽  
Weddell Sea ◽  
Ice Thickness ◽  
Sea Ice Extent ◽  
Sea Ice Thickness ◽  
Earth Observing System ◽  
Pack Ice ◽  
Snow Water ◽  
The Mean ◽  
Seasonal And Interannual Variations

AbstractSea-ice freeboard heights for 17 ICESat campaign periods from 2003 to 2009 are derived from ICESat data. Freeboard is combined with snow depth from Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) data and nominal densities of snow, water and sea ice, to estimate sea-ice thickness. Sea-ice freeboard and thickness distributions show clear seasonal variations that reflect the yearly cycle of growth and decay of the Weddell Sea (Antarctica) pack ice. During October–November, sea ice grows to its seasonal maximum both in area and thickness; the mean freeboards are 0.33–0.41m and the mean thicknesses are 2.10–2.59 m. During February–March, thinner sea ice melts away and the sea-ice pack is mainly distributed in the west Weddell Sea; the mean freeboards are 0.35–0.46m and the mean thicknesses are 1.48–1.94 m. During May–June, the mean freeboards and thicknesses are 0.26–0.29m and 1.32–1.37 m, respectively. the 6 year trends in sea-ice extent and volume are (0.023±0.051)×106 km2 a–1 (0.45% a–1) and (0.007±0.092)×103 km3 a–1 (0.08% a–1); however, the large standard deviations indicate that these positive trends are not statistically significant.

Deglacial history of the West Antarctic Ice Sheet in the Weddell Sea embayment: Constraints on past ice volume change

Geology ◽  
2010 ◽  
Vol 38 (5) ◽  
pp. 411-414 ◽  
Author(s):  
Michael J. Bentley ◽  
Christopher J. Fogwill ◽  
Anne M. Le Brocq ◽  
Alun L. Hubbard ◽  
David E. Sugden ◽  
...  
Keyword(s):  
Volume Change ◽  
Ice Sheet ◽  
Weddell Sea ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
Ice Volume ◽  
West Antarctic ◽  
History Of

Sea ice deformation and thickness in the Western Ross Sea

2021 ◽  
Author(s):  
Wolfgang Rack ◽  
Daniel Price ◽  
Christian Haas ◽  
Patricia J. Langhorne ◽  
Greg H. Leonard
Keyword(s):  
Sea Ice ◽  
Satellite Images ◽  
Ross Sea ◽  
Thickness Distribution ◽  
Ice Thickness ◽  
Ice Dynamics ◽  
Sea Ice Thickness ◽  
Ice Volume ◽  
Terra Nova Bay ◽  
Western Ross Sea

<p>Sea ice cover is arguably the longest and best observed climate variable from space, with over four decades of highly reliable daily records of extent in both hemispheres. In Antarctica, a slight positive decadal trend in sea ice cover is driven by changes in the western Ross Sea, where a variation in weather patterns over the wider region forced a change in meridional winds. The distinguishing wind driven sea ice process in the western Ross Sea is the regular occurrence of the Ross Sea, McMurdo Sound, and Terra Nova Bay polynyas. Trends in sea ice volume and mass in this area unknown, because ice thickness and dynamics are particularly hard to measure.</p><p>Here we present the first comprehensive and direct assessment of large-scale sea-ice thickness distribution in the western Ross Sea. Using an airborne electromagnetic induction (AEM) ice thickness sensor towed by a fixed wing aircraft (Basler BT-67), we observed in November 2017 over a distance of 800 km significantly thicker ice than expected from thermodynamic growth alone. By means of time series of satellite images and wind data we relate the observed thickness distribution to satellite derived ice dynamics and wind data. Strong southerly winds with speeds of up to 25 ms<sup>-1</sup> in early October deformed the pack ice, which was surveyed more than a month later.</p><p>We found strongly deformed ice with a mean and maximum thickness of 2.0 and 15.6 m, respectively. Sea-ice thickness gradients are highest within 100-200 km of polynyas, where the mean thickness of the thickest 10% of ice is 7.6 m. From comparison with aerial photographs and satellite images we conclude that ice preferentially grows in deformational ridges; about 43% of the sea ice volume in the area between McMurdo Sound and Terra Nova Bay is concentrated in more than 3 m thick ridges which cover about 15% of the surveyed area. Overall, 80% of the ice was found to be heavily deformed and concentrated in ridges up to 11.8 m thick.</p><p>Our observations hold a link between wind driven ice dynamics and the ice mass exported from the western Ross Sea. The sea ice statistics highlighted in this contribution forms a basis for improved satellite derived mass balance assessments and the evaluation of sea ice simulations.</p>

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