Improved Antarctic surface mass balance remote sensing using ASCAT
Alexander D. Fraser

Authors

Alexander D. Fraser
Antarctic Climate & Ecosystems Cooperative Research Centre,
University of Tasmania, Private Bag 80, Hobart, Tasmania, 7001, Australia

Simon Wotherspoon
Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, Tasmania 7001, Australia

Hiroyuki Enomoto
National Institute of Polar Research, 10-3 Midori-cho, Tachikawa-shi, Tokyo, 190-8518, Japan

Neal W. Young
Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia;
Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania, 7001, Australia

Abstract

Large scale distribution of Antarctic Surface Mass Balance (SMB) is currently poorly understood. High quality in situ measurements of SMB are sparse, particularly in the interior of the continent. Remote sensing can be used to guide interpolation between in situ measurements. Previously, passive microwave polarisation ratio, which is sensitive to the density of horizons of different dielectric properties in the upper snowpack (a proxy for SMB), has been used to guide interpolation of SMB points in Antarctica. We present evidence that maps of alternative parameters may be more suitable maps upon which to base interpolated fields. These maps come from the EUMETSAT Advanced Scatterometer (ASCAT) C-band scatterometer, which was launched in 2007. In particular, we use the "A" (isotropic component of backscatter, sensitive to grain size within the C-band penetration depth of ~ 20 m) and "B" (linear component of backscatter dependence on incidence angle, sensitive to grain size profile). Importantly, these maps are sensitive to recently-mapped extensive areas of surface wind glaze which are areas of near-zero net accumulation, and thus are less prone to overestimation of SMB compared with earlier large-scale SMB maps. A further focus of this work is a comparison of several statistical interpolation methods, including a careful consideration of the statistical treatment of negative SMB values. A primary output of this work is a new SMB map of the Antarctic continent based on these improved fields.