Spring and Summer Spatial Evolution of Blue Ice Areas in Antarctica

Abstract

Blue ice areas (BIAs) are relevant ablation surfaces present on the Antarctic continent, mainly located in proximity of the coast or mountainous zones, in sloping areas. Featuring negative values of surface mass balance, in a continent where this parameter is averagely positive, their study gains of importance, in particular regarding their evolution in time and space and the reasons of their variations. Therefore, taking advantage of remote sensing techniques and satellite products, we analysed the intra-annual BIA variation in 2000-2021 spring-summer periods. Basing the detection on topographic slope and albedo values from MCD43A3 product of Moderate Resolution Imaging Spectroradiometer (MODIS), trends are detected for all the analysed seasons, showing a steady and significant increase from the spring to the summer and only in half of the cases a final decrease in early autumn. Comparing these areal patterns with meteorological parameters (i.e., air temperature and wind speed) acquired by an automatic weather station located on the Amery Ice Shelf (Eastern Antarctica), a relation between positive temperatures and BIA increase was found (R = 0.60), possibly due to snow melting or sublimation processes, which expose the beneath bare blue ice. In addition, weak relations between area increase and high and steady wind speed conditions are detected. Finally, the areal decrease in early autumn observed in a certain number of seasons could be explained with intense phenomena of melting, as a result of continuing days of positive air temperatures, which lead to the formation of drainage systems, or with extreme solid precipitation events. In both the cases, water and snow cover the BIAs, making them impossible to be detected from remote techniques.