Seasonal and interannual variability of the landfast ice mass balance between 2009 and 2018 in Prydz Bay, East Antarctica

Abstract

Abstract. Landfast ice (LFI) plays a crucial role for both the climate and the ecosystem of the Antarctic coastal regions. We investigate the snow and LFI mass balance in Prydz Bay using observations from 11 sea ice mass balance buoys (IMBs). The buoys were deployed offshore from the Chinese Zhongshan Station (ZS) and Australian Davis Station (DS), with the measurements covering the ice seasons of 2009–2010, 2013–2016, and 2018. The observed annual maximum ice thickness and snow depth were 1.59 ± 0.17 and 0.11–0.76 m off ZS and 1.64 ± 0.08 and 0.11–0.38 m off DS, respectively. Early in the ice growth season (May–September), the LFI basal growth rate near DS (0.6 ± 0.2 cm d−1) was larger than that around ZS (0.5 ± 0.2 cm d−1). This is attributed to cooler air temperature (AT) and lower oceanic heat flux at that time in the DS region. Air temperature anomalies were more important in regulating the LFI growth rate at that time because of thinner sea ice having a weaker thermal inertia relative to thick ice in later seasons. Interannual and local spatial variabilities for the seasonality of LFI mass balance identified at ZS are larger than at DS due to local differences in topography and katabatic wind regime. Snow ice contributed up to 27 % of the LFI total ice thickness at the offshore site close to ground icebergs off ZS because of the substantial snow accumulation. Offshore from ZS, the supercooled water was observed at the sites close to the Dålk Glacier from July to October, which reduced the oceanic heat flux and promoted the LFI growth. During late austral spring and summer, the increased oceanic heat flux led to a reduction of LFI growth at all investigated sites. The variability of LFI properties across the study domain prevailed at interannual timescales, over any trend during the recent decades. Based on the results derived from this study, we argue that an increased understanding of snow (on LFI) processes, local atmospheric and oceanic conditions, as well as coastal morphology and bathymetry, are required to improve the Antarctic LFI modeling.

Annual evolution of the ice–ocean interaction beneath landfast ice in Prydz Bay, East Antarctica

“…Bulk A u * 0 = u w 2 + v w 2 1/4 (8) Sirevaag ( 2009) 1.6 cm d −1 on 10 May 2021. The monthly mean growth rate was largest in May (0.8 ± 0.4 cm d −1 ) and smallest in October (0.1 ± 0.2 cm d −1 ), which is similar to the nearshore observations at Zhongshan Station in 2006 (Lei et al, 2010) and in 2012 (Zhao et al, 2019) but different to the offshore cases around this region, especially when grounded icebergs existed (Li et al, 2023).…”

A new sea ice concentration product in the polar regions derived from the FengYun-3 MWRI sensors

“…The increase in snow wetness usually leads to an increase in TB of about 10-60 K, while the increase in snow grain size, which would cause the geophysical properties of snow cover to be very close to the surface scattering layer of sea ice, typically leads to a decrease in TB of about 15-35 K, resulting in large uncertainty of SIC (Kern et al, 2016). With the increase in snow depth, e.g., >0.4 m, the corresponding increased snow load may lead to a negative ice freeboard, especially for the thin ice in the Antarctic, resulting in the slush layer appearing between the snow cover and the ice layer (Li et al, 2023). However, such a slush layer is often thin, and the surface covered with thick snow will generally stay dry.…”

Modeling the Trooz Glacier’s movement using air temperature data and satellite SAR observations in 2015–2022

“…This is associated with the significant length of the coastline (18.000 km) as well as gaps in our knowledge about the current rates of ice cover change. In particular, this is caused by spatiotemporal changes in the velocity of glaciers, even for relatively small areas (within 100 km 2 ) (Tretyak, 2016;Li et al, 2023;Miles et al, 2023).…”