Sustainable observations of landfast sea ice in the cryosphere:a case study at the Liaodong Bay,Bohai Sea,North China

Sustainable monitoring of sea ice is crucial for better understanding air-ice-ocean interactions and identifying new processes. However, it is an expensive process particularly for the polar cryosphere environment. The seasonal ice-covered sea area can be used as a test bed for cryosphere-related process studies due to convenient access and conduction of field work, and the seasonal regime variation of the Arctic sea ice resulting from climate changes. In this paper, a small landfast sea ice monitoring program has been carried out for four consecutive seasons at Jiangjunshi Port, the Bohai Sea, North China, analyzing the temperature and salinity of air, ice and ocean and discussing the influence on mechanical properties. The effect of air temperature on sea ice temperature is focused. During low-temperature periods, the maximum correlation coefficient between air temperature and ice temperature, along with temperature fluctuation within ice, decreases as ice depth increases. Ice salinity was measured using ice core sampling and ice crumb sampling, with ice crumb salinity twice larger compared to ice core sampling when the ice temperature is-3 ℃. Ice salinity variations with ice temperature and the salinity profiles were fitted. Analysis of the profiles of under-ice seawater salinity reveals the presence of a high-salinity layer near the bottom of sea ice during the initial stage of sea ice growth. Based on the dynamic changes in sea ice temperature and sea ice salinity, this study evaluates the mechanical properties of sea ice, with the fitting determination coefficients of the obtained parameterized formulas significantly better than those reported in current research.