Temporal variations of Antarctic blue ice extent: a possible mass balance indicator

Abstract

The mass balance of the Antarctic ice sheet has been one of the main interests of the scientific community because of its impact on sea level rise. Blue ice areas are areas of exposed ice where the surface mass balance is negative by sublimation. The relationship between surface mass balance and temporal variations of Antarctic blue ice extent is not clear. This study investigates the temporal variations of 33 sites of blue ice extent with regard to the rate of surface elevation change by employing Landsat TM/ETM+ as well as radar altimetry-based rates of elevation change. The correlations between extent of blue ice areas and surface mass balance are analysed. The correlation generally is not systematic (r = −0.245). It may not be appropriate to use temporal variations in extent of blue ice areas as indicators of mass balance of the Antarctic ice sheet because of large interannual variations in the extent of blue ice areas caused by short term events of accumulation/ablation. Blue ice areas that are located at low elevations (r = −0.120) and far from nearby nunataks (r = −0.194) show low correlations while blue ice areas located in stable environments, such as high elevations (r = −0.516) and close to nearby nunataks (r = −0.783) may be useful as mass balance indicators showing high correlations. Monitoring the expansion of blue ice areas with regard to negative change in elevation (r = −0.510) rather than monitoring the decrease of the extent of blue ice areas with regard to positive change in elevation (r = 0.108) is more useful as a mass balance indicator. There is probably a systematic linkage between temporal variations in extent of blue ice areas and changes of surface elevation for blue ice areas that are at high elevations, close to nearby nunataks, and experiencing expansion.