Response of Fast Ice to Ground Penetrating Radar and Backscattering Coefficient from Scatterometer In Larsemann Hills, East Antarctica

The study presents inter-annual variations in the backscatter response of fast ice (sea ice attached to the coast) to C band Advanced Scatterometer (ASCAT) (2012–2016). It also analyses the Ground Penetrating Radar (GPR) observations collected during the 35th Indian Scientific Expedition to Antarctica (ISEA, 2015–16) for identification of different fast ice features and to measure fast ice depth in the Larsemann Hills area, East Antarctica. Apart from clear demarcation of features like melt water channels, frozen icebergs within fast ice and underlying topography near island, GPR provided fast ice depth information, which was used to understand backscatter response. The seasonal variations of C band backscatter were caused due to changes in snow thickness, time of freezing and sporadic melt/freeze events apart from summer melt. The backscatter response to NOAA high resolution blended daily sea surface temperature (SST) variations indicate that sudden rise/fall in backscatter during winter is probably due to sporadic melt/freeze events caused by rise/fall in SST. The results show volumetric contribution from sheet ice and domination of snow metamorphism towards increase in backscatter over fast ice. This study highlights the importance of monitoring backscatter response of fast ice to determine its state and condition. Depending on the characteristics of backscatter inter-annual curve, information about time of freeze up, melt season, ice build-up, and sporadic freeze/ thaw events can be inferred which play an important role in the energy budget of Antarctica.