Decadal Variations of Sea Ice Thickness in the Amundsen‐Bellingshausen and Weddell Seas Retrieved From ICESat and IceBridge Laser Altimetry, 2003–2017

Abstract

AbstractThe changing distributions of sea ice thickness in different regions around Antarctica are important metrics of climate variability, but estimates have large uncertainties. Here, we analyze laser altimetry data from ICESat and IceBridge to generate a record of total freeboard and sea ice thickness in the Amundsen‐Bellingshausen and Weddell seas during austral springs from 2003 to 2017. We improve the buoyancy approach (BOC) to estimate sea ice thickness from total freeboard without altimetry‐coincident measurements of snow depth. The sea ice thickness estimated by the improved BOC agrees well with field measurements and is slightly larger than those derived by previous approaches of zero ice freeboard and empirical relationship. The average sea ice thickness had large interannual variations with no significant trend in both seas from 2003 to 2017. Although sea ice thickness usually did not covary with sea ice extent in these regions, sea ice thickness showed a similar rapid decline with ice extents in the Weddell Sea during 2014–2017. The nearly continuous long‐term record of sea ice thickness is of great significance for the sea ice and global climatic model communities, especially given the future extension of the record using measurements from ICESat‐2 launched in late 2018.