An Observation of Antarctic Marginal Subglacial Lake using Cryosat-2 SARin mode

Abstract:

The surface height above active subglacial lake (SGL) varies in accordance with the water storage of lake beneath ice-sheet. Thus, satellite altimeters accurately measuring the ice surface height have discovered numbers of SGLs. In this study, we detect Antarctic SGLs using Cryosat-2 without any auxiliary data. The SARin mode of Cyrosat-2 is designed to retrieve the elevation over steep slope regions, such as margin of ice-sheet or ice-stream. The high-resolution processing of SARin mode yielding the elevation change rate (=Δh/Δt) enables us to verify the specific 2-D boundary of lake and even the small-scale uncategorized lakes. In the Whillans and Mercer Ice Streams (WIS and MIS), drainage or refilling events of 9 SGLs are apparent in Cyrosat-2 era, and one of those is likely an uncategorized lake. In addition, the ice thickening upstream of WIS and MIS, which might be provoked by the deceleration downstream of WIS, alternates between high and low rate. It might be associated with massive drainage event of lake “Conway”. In the Kamb Ice Stream (KIS), most of previously known SGLs are not observed except for only one (Kamb trunk1) due to the limited spatial coverage of SARin mode operation. However, two additional lakes (located in 82.304S/147.980W and 82.477S/150.585W, respectively) are discovered at the downstream of Kamb trunk 1 lake. Similar approach is applied at slightly rugged terrain, which is located on the upstream of David Glacier. The drainage event of David 1 SGL is apparent, but the precise location of the lake is significantly (about twenty kilometers) different from previous ICESat measurement. Since ICESat measurements have limited temporal/spatial resolutions, we expect that Cryosat-2 have more optimal performance for measuring Antarctic Marginal SGLs.