Seasonal and interannual variations in landfast ice mass balance between 2009–2018 in Prydz Bay, East Antarctica

Abstract

Landfast ice (LFI) is an indispensable component in the Antarctic coastal system, which is very important for coastal climate and ecological processes. However, the regional differences of LFI mass balance with respect to the seasonal and inter-annual variations and the impact factors responsible to those differences have not been investigated systematically in the Prydz Bay, i.e., the third largest bay along the Antarctic coast.  We analyzed the data measured by 11 ice mass balance buoys (IMBs) obtained in the coastal areas off the Chinese Zhongshan station (ZS) and Australian Davis station (DS), and covered 2009–2010, 2013–2016 and 2018 ice seasons. We identified the local spatial changes in LFI based on the data.  The observed annual maximum ice thickness for LFI off ZS (DS) was 1.59±0.17 m (1.64±0.08 m), with the dominant influencing factors of air temperature anomaly, snow depth atop, local topography and wind regime, and oceanic heat flux. Larger interannual and local spatial variabilities for the seasonality of LFI mass balance were observed at ZS than at DS because of the differences in local topography and katabatic wind regime. LFI at DS (0.6±0.2 cm d-1) grew faster in winter due to the relatively low air temperature and small oceanic heat flux compared to that at ZS (0.5±0.2 cm d-1). Snow ice contributes up to 26% of the observed LFI maximum ice thickness at the offshore site close to ground icebergs off ZS because of substantial snow accumulation. Oceanic heat flux would promote the LFI growth during winter at the sites nearby Dålk Glacier off ZS because of the supercooled meltwater. At interannual timescale, we find that variability of LFI properties across the study domain prevailed, over any trend during the recent decades. Our results suggests that increased understanding of local atmospheric and oceanic conditions, as well as surface morphology and coastal bathymetry, are required to improve Antarctic LFI modelling at local and regional scale.