Comparison of Microwave Backscatter Anisotropy Parameterizations of the Antarctic Ice Sheet

The Antarctic Ice Sheet exhibits a strong anisotropy in microwave backscatter, both as a function of azimuth angle and incidenceangle. This anisotropy arises as a result of i) the alignment of roughness elements and other wind-related surface and sub-surfacefeatures, as well as ii) internal layers a...

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Bibliographic Details
Published in:The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
Main Authors: Fraser, Alexander Donald, Young, NW, Adams, ND
Format: Conference Object
Language:English
Published: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences 2012
Subjects:
Earth Sciences
Geophysics
Geophysics not elsewhere classified
Antarctic
Greenland
The Antarctic
Antarc*
Antarctica
Ice Sheet
Online Access:https://doi.org/10.5194/isprsarchives-XXXIX-B8-573-2012
http://ecite.utas.edu.au/86068
Description
Summary:The Antarctic Ice Sheet exhibits a strong anisotropy in microwave backscatter, both as a function of azimuth angle and incidenceangle. This anisotropy arises as a result of i) the alignment of roughness elements and other wind-related surface and sub-surfacefeatures, as well as ii) internal layers and snow grain size gradient within the snowpack. As a result of its antenna configuration, theEuropean Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Advanced SCATterometer (ASCAT) satelliteinstrument is able to observe much of the continent with a large azimuth and incidence angle diversity. A lack of azimuth and incidencediversity has restricted previous backscatter parameterisations to relatively simple bi-sinusoidal (azimuth angle) and linear (incidenceangle) parameterisations. Using ASCAT, we show that a better fit can be obtained using a cubic incidence angle function and a Fourierseries of up to four terms for parameterisation of the azimuth angle anisotropy. Scatterometer instruments have previously been usedin Greenland to retrieve accumulation rate by observing the change in backscatter as a function of incidence angle. Here we presentpreliminary results of an empirical study linking the isotropic component and incidence angle dependence to snow accumulation ratein Antarctica, using snow stake measurements as ground truthing.

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