Diurnal Scale Controls on C-Band Microwave Backscatter From Snow-Covered First-Year Sea Ice During the Transition From Late Winter to Early Melt

Early-summer melt pond fraction is predicted using late-winter C-band backscatter of snow-covered first-year sea ice. Aerial photographs were acquired during an early-summer 2012 field campaign in Resolute Passage, Nunavut, Canada, on smooth first-year sea ice to estimate the melt pond fraction. RADARSAT-2 Synthetic Aperture Radar (SAR) data were acquired over the study area in late winter prior to melt onset. Correlations between the melt pond fractions and late-winter linear and polarimetric SAR parameters and texture measures derived from the SAR parameters are utilized to develop multivariate regression models that predict melt pond fractions. The results demonstrate substantial capability of the regression models to predict melt pond fractions for all SAR incidence angle ranges. The combination of the most significant linear, polarimetric and texture parameters provide the best model at far-range incidence angles, with an R 2 of 0.62 and a pond fraction RMSE of 0.09. Near- and mid- range incidence angle models provide R 2 values of 0.57 and 0.61, respectively, with an RMSE of 0.11. The strength of the regression models improves when SAR parameters are combined with texture parameters. These predictions also serve as a proxy to estimate snow thickness distributions during late winter as higher pond fractions evolve from thinner snow cover.

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Snow Thickness Estimation on First-Year Sea Ice from Late Winter Spaceborne Scatterometer Backscatter Variance

Remote Sensing ◽

10.3390/rs11040417 ◽

2019 ◽

Vol 11 (4) ◽

pp. 417 ◽

Cited By ~ 5

Author(s):

John Yackel ◽

Torsten Geldsetzer ◽

Mallik Mahmud ◽

Vishnu Nandan ◽

Stephen Howell ◽

...

Keyword(s):

Sea Ice ◽

Snow Cover ◽

Winter Season ◽

Late Winter ◽

First Year ◽

Snow Layer ◽

Independent Case ◽

Brine Volume ◽

Snow Thickness

Ku- and C-band spaceborne scatterometer sigma nought (σ°) backscatter data of snow covered landfast first-year sea ice from the Canadian Arctic Archipelago are acquired during the winter season with coincident in situ snow-thickness observations. Our objective is to describe a methodological framework for estimating relative snow thickness on first-year sea ice based on the variance in σ° from daily time series ASCAT and QuikSCAT scatterometer measurements during the late winter season prior to melt onset. We first describe our theoretical basis for this approach, including assumptions and conditions under which the method is ideally suited and then present observational evidence from four independent case studies to support our hypothesis. Results suggest that the approach can provide a relative measure of snow thickness prior to σ° detected melt onset at both Ku- and C-band frequencies. We observe that, during the late winter season, a thinner snow cover displays a larger variance in daily σ° compared to a thicker snow cover on first-year sea ice. This is because for a given increase in air temperature, a thinner snow cover manifests a larger increase in basal snow layer brine volume owing to its higher thermal conductivity, a larger increase in the dielectric constant and a larger increase in σ° at both Ku- and C bands. The approach does not apply when snow thickness distributions on first-year sea ice being compared are statistically similar, indicating that similar late winter σ° variances likely indicate regions of similar snow thickness.

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Multi-frequency microwave backscatter indices from saline snow covers on smooth first-year sea ice

2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) ◽

10.1109/igarss.2017.8126967 ◽

2017 ◽

Author(s):

Vishnu Nandan ◽

Torsten Geldsetzer ◽

Mallik Mahmud ◽

John Yackel ◽

Mark C. Fuller ◽

...

Keyword(s):

Sea Ice ◽

First Year ◽

Microwave Backscatter

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An intercomparison between AMSR-E snow-depth and satellite C- and Ku-band radar backscatter data for Antarctic sea ice

Annals of Glaciology ◽

10.3189/172756411795931750 ◽

2011 ◽

Vol 52 (57) ◽

pp. 279-290 ◽

Cited By ~ 14

Author(s):

Stefan Kern ◽

Burcu Ozsoy-Cicek ◽

Sascha Willmes ◽

Marcel Nicolaus ◽

Christian Haas ◽

...

Keyword(s):

Sea Ice ◽

Snow Depth ◽

Weddell Sea ◽

Late Winter ◽

First Year ◽

Radar Backscatter ◽

Antarctic Sea Ice ◽

Ridged Ice ◽

Ice Fraction ◽

Ku Band

AbstractAdvanced Microwave Scanning Radiometer (AMSR-E) snow-depth data for Antarctic sea ice are compared with ship-based visual observations of snow depth, ice type and ridged-ice fraction, and with satellite C-band and Ku-band radar backscatter observations for two ship cruises into the Weddell Sea (ISPOL 2004–05,WWOS 2006) and one cruise into the Bellingshausen Sea (SIMBA 2007) during late winter/spring. Most (>75%) AMSR-E and ship-based snow-depth observations agree within 0.2 m during WWOS and SIMBA. Remaining observations indicate substantial underestimations of snow depths by AMSR-E data. These underestimations tend to increase with the ridged-ice fraction for WWOS and SIMBA. In areas with large snow depths, a combination of relatively stable low C-band radar backscatter and variable Ku-band radar backscatter is associated with undeformed first-year ice and may indicate snow metamorphism at this time of year during SIMBA. In areas with small snow depths, a combination of relatively stable low Ku-band radar backscatter, high C-band radar backscatter and low C-band radar backscatter standard deviations is associated with rough first-year ice during SIMBA. This information can help to better understand causes of the observed AMSR-E snow-depth bias during late-winter/spring conditions with decreasing average snow depth and to delineate areas where this bias occurs.

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A Subice Suction Corer for Sampling Epontic Ice Algae

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f88-067 ◽

1988 ◽

Vol 45 (3) ◽

pp. 562-568 ◽

Cited By ~ 18

Author(s):

Harold E. Welch ◽

Martin A. Bergmann ◽

John K. Jorgenson ◽

William Burton

Keyword(s):

Sea Ice ◽

Quantitative Assessment ◽

Early Spring ◽

Late Winter ◽

First Year ◽

Ice Algae ◽

Sources Of Error

Standard SIPRE coring was compared with a new Subice Suction Corer and cores taken by diver for the quantitative assessment of epontic (subice) algae on first-year congelation sea ice at Resolute, N.W.T., Canada (≈75°N). The diver cores were probably most accurate but were slow and costly. SIPRE coring was as good as other techniques in late winter and early spring but gave progressively poorer (under) estimates as the season progressed, with up to 90% of the ice algae being lost from SIPRE cores by June. The Subice Suction Corer was fast, easy to operate, cheap, and gave results comparable with samples obtained by diving. Sources of error are discussed.

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Analyses of c-band microwave backscatter to wind-roughened first-year sea ice melt ponds

IEEE International IEEE International IEEE International Geoscience and Remote Sensing Symposium, 2004. IGARSS '04. Proceedings. 2004 ◽

10.1109/igarss.2004.1370334 ◽

2004 ◽

Author(s):

R.K. Scharien ◽

J.J. Yackel

Keyword(s):

Sea Ice ◽

First Year ◽

Ice Melt ◽

Melt Ponds ◽

Microwave Backscatter

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Temporal evolution of physical and dielectric properties of sea ice and snow during the early melt season: observations from SIMS ’90 experiment

Journal of Glaciology ◽

10.3189/s0022143000003762 ◽

1994 ◽

Vol 40 (134) ◽

pp. 16-30 ◽

Cited By ~ 1

Author(s):

Mohammede.E Shokr ◽

David G. Barber

Keyword(s):

Surface Layer ◽

Dielectric Properties ◽

Sea Ice ◽

Temporal Evolution ◽

Daily Basis ◽

Complex Dielectric Constant ◽

Late Winter ◽

First Year ◽

Monitoring Site ◽

Ice Surface

AbstractThe first field experiment in the 5 year seasonal Sea Ice Monitoring Site (SIMS) program was conducted in Resolute Passage, Canadian Eastern Arctic, between 15 May and 8 June 1990. This period signals the early melt season of sea ice in that region. A standard array of ice and snow measurements was collected on a daily basis from first-year and multi-year ice to monitor temporal evolution. Measurements included ice salinity, ice temperature and ice-surface roughness, snow salinity, snow temperature, snow density and snow depth. The complex dielectric constant of sea ice was computed from these measurements. Rapid desalination of first-year ice was noticed in the surface layer. Towards the end of the experiment period, salinities of the snow-hoar layer were higher than those of the ice-surface layer. Variation in air temperature is replicated by ice-surface temperature but not by the salinity or dielectric properties. No temporal variation in permittivity and dielectric loss was observed for first-year ice, but a slight increase in both parameters was observed for multi-year ice. As a result, a slight decrease in the microwave-penetration depth was observed for multi-year ice. Physical properties of ice and snow were compared against results obtained from other experiments conducted in different ice-formation regions in the late winter and in the early melt season.

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Ku-, X- and C-Band Microwave Backscatter Indices from Saline Snow Covers on Arctic First-Year Sea Ice

Remote Sensing ◽

10.3390/rs9070757 ◽

2017 ◽

Vol 9 (7) ◽

pp. 757 ◽

Cited By ~ 7

Author(s):

◽

Keyword(s):

Sea Ice ◽

First Year ◽

Microwave Backscatter

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Comparison of a coupled snow thermodynamic and radiative transfer model with in situ active microwave signatures of snow-covered smooth first-year sea ice

The Cryosphere ◽

10.5194/tc-9-2149-2015 ◽

2015 ◽

Vol 9 (6) ◽

pp. 2149-2161 ◽

Cited By ~ 7

Author(s):

M. C. Fuller ◽

T. Geldsetzer ◽

J. Yackel ◽

J. P. S. Gill

Keyword(s):

Sea Ice ◽

Reanalysis Data ◽

Physical Models ◽

Radiative Transfer Model ◽

Wave Radiation ◽

First Year ◽

Transfer Model ◽

Long Wave ◽

Microwave Backscatter

Abstract. Within the context of developing data inversion and assimilation techniques for C-band backscatter over sea ice, snow physical models may be used to drive backscatter models for comparison and optimization with satellite observations. Such modeling has the potential to enhance understanding of snow on sea-ice properties required for unambiguous interpretation of active microwave imagery. An end-to-end modeling suite is introduced, incorporating regional reanalysis data (NARR), a snow model (SNTHERM89.rev4), and a multilayer snow and ice active microwave backscatter model (MSIB). This modeling suite is assessed against measured snow on sea-ice geophysical properties and against measured active microwave backscatter. NARR data were input to the SNTHERM snow thermodynamic model in order to drive the MSIB model for comparison to detailed geophysical measurements and surface-based observations of C-band backscatter of snow on first-year sea ice. The NARR variables were correlated to available in situ measurements with the exception of long-wave incoming radiation and relative humidity, which impacted SNTHERM simulations of snow temperature. SNTHERM snow grain size and density were comparable to observations. The first assessment of the forward assimilation technique developed in this work required the application of in situ salinity profiles to one SNTHERM snow profile, which resulted in simulated backscatter close to that driven by in situ snow properties. In other test cases, the simulated backscatter remained 4–6 dB below observed for higher incidence angles and when compared to an average simulated backscatter of in situ end-member snow covers. Development of C-band inversion and assimilation schemes employing SNTHERM89.rev4 should consider sensitivity of the model to bias in incoming long-wave radiation, the effects of brine, and the inability of SNTHERM89.Rev4 to simulate water accumulation and refreezing at the bottom and mid-layers of the snowpack. These impact thermodynamic response, brine wicking and volume processes, snow dielectrics, and thus microwave backscatter from snow on first-year sea ice.

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