C-band backscatter from a complexly-layered snow cover on first-year sea ice

2014 ◽  
Vol 28 (16) ◽  
pp. 4614-4625 ◽  
Author(s):  
M. Christopher Fuller ◽  
Torsten Geldsetzer ◽  
Jagvijay P. S. Gill ◽  
John J. Yackel ◽  
Chris Derksen
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
First Year

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

2019 ◽  
Vol 11 (4) ◽  
pp. 417 ◽  
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.

Multi-frequency polarimetric microwave observations of snow cover on first-year Arctic sea ice

2015 ◽  
Author(s):  
Vishnu Nandan ◽  
John J. Yackel ◽  
Jagvijay P. S. Gill ◽  
Torsten Geldsetzer ◽  
Mark C. Fuller
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
Arctic Sea Ice ◽  
First Year ◽  
Arctic Sea

Multifrequency Microwave Backscatter From a Highly Saline Snow Cover on Smooth First-Year Sea Ice: First-Order Theoretical Modeling

2017 ◽  
Vol 55 (4) ◽  
pp. 2177-2190 ◽  
Author(s):  
Vishnu Nandan ◽  
Torsten Geldsetzer ◽  
John J. Yackel ◽  
Tanvir Islam ◽  
Jagvijay P. S. Gill ◽  
...  
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
Theoretical Modeling ◽  
First Year ◽  
First Order ◽  
Microwave Backscatter

scholarly journals Upwelling Irradiance below Sea Ice—PAR Intensities and Spectral Distributions

2021 ◽  
Vol 9 (8) ◽  
pp. 830
Author(s):  
Lars Chresten Lund-Hansen ◽  
Michael Bjerg-Nielsen ◽  
Tanja Stratmann ◽  
Ian Hawes ◽  
Brian K. Sorrell
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
Daily Maximum ◽  
First Year ◽  
Ice Algae ◽  
Sea Ice Algae ◽  
Spectral Distributions ◽  
And Performance ◽  
Light Saturation Point ◽  
Upwelling And Downwelling

Upwelling and downwelling spectral (320–920 nm) distributions and photosynthetic active radiation (PAR) intensities were measured below a first-year land-fast sea ice in a western Greenland fjord with and without a snow cover. Time-series of surface upwelling PAR, downwelling PAR, and under-ice PAR were also obtained. Spectral distributions of upwelling and downwelling irradiances were similar except for reduced intensities in the UV, the red, and NIR parts of the spectrum when the ice was snow-covered. Upwelling PAR amounted to about 10% of downwelling intensities, giving 5.1 µmol photons m−2 s−1 at the bottom of the ice with a snow cover and 8.2 µmol photons m−2 s−1 without. PAR partitioning analyses showed that the upwelling was related to scattering by suspended particles in the water column. A snow melt increased under-ice daily maximum downwelling PAR from 50 to 180 µmol photons m−2 s−1 and overall under-ice PAR of 55 and 198 µmol photons m−2 s−1 with 10% upwelling. It is concluded that upwelling PAR below sea ice might be an important factor regarding sea ice algae photophysiology and performance with a 10% higher PAR; specifically when PAR > Ek the light saturation point of the sea ice algae.

scholarly journals The effects of additional black carbon on Arctic sea ice surface albedo: variation with sea ice type and snow cover

2013 ◽  
Vol 7 (2) ◽  
pp. 943-973
Author(s):  
A. A. Marks ◽  
M. D. King
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
Black Carbon ◽  
Surface Albedo ◽  
Arctic Sea Ice ◽  
Radiative Transfer Model ◽  
First Year ◽  
Transfer Model ◽  
Ice Surface ◽  
Carbon Additions

Abstract. Black carbon in sea ice will decrease sea ice surface albedo through increased absorption of incident solar radiation, exacerbating sea ice melting. Previous literature has reported different albedo responses to additions of black carbon in sea ice and has not considered how a snow cover may mitigate the effect of black carbon in sea ice. Sea ice is predominately snow covered. Visible light absorption and light scattering coefficients are calculated for a typical first year and multi-year sea ice and "dry" and "wet" snow types that suggest black carbon is the dominating absorbing impurity. The albedo response of first year and multi-year sea ice to increasing black carbon, from 1–1024 ng g−1, in a top 5 cm layer of a 155 cm thick sea ice was calculated using the radiative transfer model: TUV-snow. Sea ice albedo is surprisingly unresponsive to black carbon additions up to 100 ng g−1 with a decrease in albedo to 98.7% of the original albedo value due to an addition of 8 ng g−1 of black carbon in first year sea ice compared to an albedo decrease to 99.6% for the same black carbon mass ratio increase in multi-year sea ice. The first year sea ice proved more responsive to black carbon additions than the multi-year ice. Comparison with previous modelling of black carbon in sea ice suggests a more scattering sea ice environment will be less responsive to black carbon additions. Snow layers on sea ice may mitigate the effects of black carbon in sea ice. "Wet" and "dry" snow layers of 0.5, 1, 2, 5 and 10 cm were added onto the sea ice surface and the snow surface albedo calculated with the same increase in black carbon in the underlying sea ice. Just a 0.5 cm layer of snow greatly diminishes the effect of black carbon on surface albedo, and a 2–5 cm layer (less than half the e-folding depth of snow) is enough to "mask" any change in surface albedo owing to additional black carbon in sea ice, but not thick enough to ignore the underlying sea ice.

Geophysical and atmospheric controls on Ku-, X- and C-band backscatter evolution from a saline snow cover on first-year sea ice from late-winter to pre-early melt

2017 ◽  
Vol 198 ◽  
pp. 425-441 ◽  
Author(s):  
Vishnu Nandan ◽  
Randall Scharien ◽  
Torsten Geldsetzer ◽  
Mallik Mahmud ◽  
John J. Yackel ◽  
...  
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
Late Winter ◽  
First Year

Ablation patterns of snow cover over smooth first-year sea ice in the Canadian Arctic

2001 ◽  
Vol 15 (18) ◽  
pp. 3559-3569 ◽  
Author(s):  
J. Iacozza ◽  
D. G. Barber
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
Canadian Arctic ◽  
First Year

Ku-, X- and C-band measured and modeled microwave backscatter from a highly saline snow cover on first-year sea ice

2016 ◽  
Vol 187 ◽  
pp. 62-75 ◽  
Author(s):  
Vishnu Nandan ◽  
Torsten Geldsetzer ◽  
Tanvir Islam ◽  
John. J. Yackel ◽  
Jagvijay P.S. Gill ◽  
...  
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
First Year ◽  
Microwave Backscatter

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

1997 ◽  
Vol 43 (143) ◽  
pp. 138-151 ◽  
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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