Annual variation of temperature and mass balance of first-year and second-year land-fast sea ice in Prydz Bay, East Antarctica

Abstract The evolution of the temperature and mass balance of first-year (FYI: Site S1) and second-year (SYI: Site S2) land-fast sea ice (LFSI) in May–November were investigated using high-resolution thermistor-string-based ice mass balance buoys, borehole measurements and a numerical sea ice model. In May, the growth rate of a 0.55 m FYI ice floe (9.2 mm day −1 ) was twice that of 1.08 m SYI (4.7 mm day −1 ) in snow-free conditions. After snow accumulation on 10 June, the growth slowed down and both reached 3.5 mm day −1 by 20 July. The observed/modelled ice thicknesses were 1.38/1.47 m for S1 (26 November) and 1.70/1.84 m for S2 (30 November). The correlation coefficients between the modelled and observed average ice temperature profiles were 0.8(vertical)/0.9(temporal) for S1 and 0.89/0.97 for S2. SYI had a higher winter cold content (32.78 MJ m −2 ) than FYI (21.01 MJ m −2 ). The modelled and observed snow depths were comparable when 50% ERA5 precipitation was used as the forcing. Snow–ice and superimposed ice formation were most sensitive to the precipitation pattern, followed by the initial snow depth and initial ice thickness. The net ice growth of both FYI and SYI were inversely related to the initial ice thickness and snow depth.