Analysis of Multiple-Angle Microwave Observations of Snow and Ice Using Cluster-Analysis Techniques

AbstractThe Nimbus-6 satellite carries the Scanning Microwave Spectrometer experiment (SCAMS) which continuously maps the Earth’s surface at two frequencies (22.235 and 31.65 GHz) and at six angles besides nadir. Cluster analysis was applied to these observations to determine the influence of various geophysical parameters on the radiometric brightness temperatures.Characteristic microwave signatures for a variety of terrain were obtained by this method; discrete clusters were distinguished for sea ice (with sub-classes for ice age and fractional ice cover) and firn (with accumulation-rate sub-classes). The availability of the angular data greatly facilitated separate determinations of the extent of continuous sea ice and mixtures of sea ice and water.

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An enhancement to sea ice motion and age products at the National Snow and Ice Data Center (NSIDC)

The Cryosphere ◽

10.5194/tc-14-1519-2020 ◽

2020 ◽

Vol 14 (5) ◽

pp. 1519-1536 ◽

Cited By ~ 9

Author(s):

Mark A. Tschudi ◽

Walter N. Meier ◽

J. Scott Stewart

Keyword(s):

Time Series ◽

Sea Ice ◽

Data Center ◽

Ice Cover ◽

Ice Age ◽

The Arctic ◽

Significant Shift ◽

Positive Trend ◽

The Impact ◽

Snow And Ice

Abstract. A new version of sea ice motion and age products includes several significant upgrades in processing, corrects known issues with the previous version, and updates the time series through 2018, with regular updates planned for the future. First, we provide a history of these NASA products distributed at the National Snow and Ice Data Center. Then we discuss the improvements to the algorithms, provide validation results for the new (Version 4) and older versions, and intercompare the two. While Version 4 algorithm changes were significant, the impact on the products is relatively minor, particularly for more recent years. The changes in Version 4 reduce motion biases by ∼ 0.01 to 0.02 cm s−1 and error standard deviations by ∼ 0.3 cm s−1. Overall, ice speed increased in Version 4 over Version 3 by 0.5 to 2.0 cm s−1 over most of the time series. Version 4 shows a higher positive trend for the Arctic of 0.21 cm s−1 per decade compared to 0.13 cm s−1 per decade for Version 3. The new version of ice age estimates indicates more older ice than Version 3, especially earlier in the record, but similar trends toward less multiyear ice. Changes in sea ice motion and age derived from the product show a significant shift in the Arctic ice cover, from a pack with a high concentration of older ice to a sea ice cover dominated by first-year ice, which is more susceptible to summer melt. We also observe an increase in the speed of the ice over the time series ≥ 30 years, which has been shown in other studies and is anticipated with the annual decrease in sea ice extent.

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Seasonal variations in the properties and structural composition of sea ice and snow cover in the Bellingshausen and Amundsen Seas, Antarctica

Journal of Glaciology ◽

10.3189/s0022143000002902 ◽

1997 ◽

Vol 43 (143) ◽

pp. 138-151 ◽

Cited By ~ 2

Author(s):

M. O. Jeffries ◽

K. Morris ◽

W.F. Weeks ◽

A. P. Worby

Keyword(s):

Sea Ice ◽

Isotopic Composition ◽

Snow Cover ◽

Sea Water ◽

Ice Cores ◽

Ice Cover ◽

Snow Accumulation ◽

Ice Formation ◽

Frazil Ice ◽

Core Sets

AbstractSixty-three ice cores were collected in the Bellingshausen and Amundsen Seas in August and September 1993 during a cruise of the R.V. Nathaniel B. Palmer. The structure and stable-isotopic composition (18O/16O) of the cores were investigated in order to understand the growth conditions and to identify the key growth processes, particularly the contribution of snow to sea-ice formation. The structure and isotopic composition of a set of 12 cores that was collected for the same purpose in the Bellingshausen Sea in March 1992 are reassessed. Frazil ice and congelation ice contribute 44% and 26%, respectively, to the composition of both the winter and summer ice-core sets, evidence that the relatively calm conditions that favour congelation-ice formation are neither as common nor as prolonged as the more turbulent conditions that favour frazil-ice growth and pancake-ice formation. Both frazil- and congelation-ice layers have an av erage thickness of 0.12 m in winter, evidence that congelation ice and pancake ice thicken primarily by dynamic processes. The thermodynamic development of the ice cover relies heavily on the formation of snow ice at the surface of floes after sea water has flooded the snow cover. Snow-ice layers have a mean thickness of 0.20 and 0.28 m in the winter and summer cores, respectively, and the contribution of snow ice to the winter (24%) and summer (16%) core sets exceeds most quantities that have been reported previously in other Antarctic pack-ice zones. The thickness and quantity of snow ice may be due to a combination of high snow-accumulation rates and snow loads, environmental conditions that favour a warm ice cover in which brine convection between the bottom and top of the ice introduces sea water to the snow/ice interface, and bottom melting losses being compensated by snow-ice formation. Layers of superimposed ice at the top of each of the summer cores make up 4.6% of the ice that was examined and they increase by a factor of 3 the quantity of snow entrained in the ice. The accumulation of superimposed ice is evidence that melting in the snow cover on Antarctic sea-ice floes ran reach an advanced stage and contribute a significant amount of snow to the total ice mass.

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Sunlight, Sea Ice, and the Ice Albedo Feedback in a Changing Arctic Sea Ice Cover

10.21236/ada601068 ◽

2013 ◽

Author(s):

Don Perovich ◽

Bonnie Light

Keyword(s):

Sea Ice ◽

Ice Cover ◽

Arctic Sea Ice ◽

Albedo Feedback ◽

Arctic Sea

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RECONSTRUCTING CHANGES IN SEA ICE COVER DURING MARINE ISOTOPE STAGE 11 FROM BERING SEA SEDIMENT CORES

10.1130/abs/2018nc-313273 ◽

2018 ◽

Author(s):

Natalie Thompson ◽

◽

Beth E. Caissie

Keyword(s):

Sea Ice ◽

Bering Sea ◽

Sediment Cores ◽

Ice Cover ◽

Marine Isotope Stage

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Thinner Sea Ice Contribution to the Remarkable Polynya Formation North of Greenland in August 2018

Advances in Atmospheric Sciences ◽

10.1007/s00376-021-0136-9 ◽

2021 ◽

Author(s):

Xiaoyi Shen ◽

Chang-Qing Ke ◽

Bin Cheng ◽

Wentao Xia ◽

Mengmeng Li ◽

...

Keyword(s):

Sea Ice ◽

Ice Cover ◽

Reanalysis Data ◽

Mean Value ◽

Ocean Model ◽

North Coast ◽

Average Value ◽

The North ◽

Wind Sea ◽

The One

AbstractIn August 2018, a remarkable polynya was observed off the north coast of Greenland, a perennial ice zone where thick sea ice cover persists. In order to investigate the formation process of this polynya, satellite observations, a coupled ice-ocean model, ocean profiling data, and atmosphere reanalysis data were applied. We found that the thinnest sea ice cover in August since 1978 (mean value of 1.1 m, compared to the average value of 2.8 m during 1978–2017) and the modest southerly wind caused by a positive North Atlantic Oscillation (mean value of 0.82, compared to the climatological value of −0.02) were responsible for the formation and maintenance of this polynya. The opening mechanism of this polynya differs from the one formed in February 2018 in the same area caused by persistent anomalously high wind. Sea ice drift patterns have become more responsive to the atmospheric forcing due to thinning of sea ice cover in this region.

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Discrimination of nano-objects via cluster analysis techniques applied to time-resolved thermo-acoustic microscopy

Ultrasonics ◽

10.1016/j.ultras.2021.106403 ◽

2021 ◽

Vol 114 ◽

pp. 106403

Author(s):

Andrea Ronchi ◽

Andrea Sterzi ◽

Marco Gandolfi ◽

Ali Belarouci ◽

Claudio Giannetti ◽

...

Keyword(s):

Cluster Analysis ◽

Acoustic Microscopy ◽

Time Resolved ◽

Analysis Techniques

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Validation of Sentinel-1-derived sea ice cover data in the Arctic

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/502/1/012032 ◽

2020 ◽

Vol 502 ◽

pp. 012032

Author(s):

Qiang Zhang ◽

Shibo Guo ◽

Yan Sun ◽

JianPing Dou ◽

Xiao-Ming Li

Keyword(s):

Sea Ice ◽

Ice Cover ◽

The Arctic

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Polar cod in jeopardy under the retreating Arctic sea ice

Communications Biology ◽

10.1038/s42003-019-0649-2 ◽

2019 ◽

Vol 2 (1) ◽

Cited By ~ 6

Author(s):

Mats Brockstedt Olsen Huserbråten ◽

Elena Eriksen ◽

Harald Gjøsæter ◽

Frode Vikebø

Keyword(s):

Sea Ice ◽

Barents Sea ◽

Keystone Species ◽

Ice Cover ◽

Arctic Sea Ice ◽

Biophysical Model ◽

The Arctic ◽

Polar Cod ◽

Arctic Sea ◽

Shelf Sea

Abstract The Arctic amplification of global warming is causing the Arctic-Atlantic ice edge to retreat at unprecedented rates. Here we show how variability and change in sea ice cover in the Barents Sea, the largest shelf sea of the Arctic, affect the population dynamics of a keystone species of the ice-associated food web, the polar cod (Boreogadus saida). The data-driven biophysical model of polar cod early life stages assembled here predicts a strong mechanistic link between survival and variation in ice cover and temperature, suggesting imminent recruitment collapse should the observed ice-reduction and heating continue. Backtracking of drifting eggs and larvae from observations also demonstrates a northward retreat of one of two clearly defined spawning assemblages, possibly in response to warming. With annual to decadal ice-predictions under development the mechanistic physical-biological links presented here represent a powerful tool for making long-term predictions for the propagation of polar cod stocks.

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