Modelling the annual cycle of landfast ice near Zhongshan Station,East Antarctica

摘要

A high resolution one-dimensional thermodynamic snow and ice(HIGHTSI)model was used to model the annual cycle of landfast ice mass and heat balance near Zhongshan Station,East Antarctica.The model was forced and initialized by meteorological and sea ice in situ observations from April 2015 to April 2016.HIGHTSI produced a reasonable snow and ice evolution in the validation experiments,with a negligible mean ice thickness bias of(0.003±0.06)m compared to in situ observations.To further examine the impact of different snow conditions on annual evolution of first-year ice(FYI),four sensitivity experiments with different precipitation schemes(0,half,normal,and double)were performed.The results showed that compared to the snow-free case,the insulation effect of snow cover decreased bottom freezing in the winter,leading to 15%–26%reduction of maximum ice thickness.Thick snow cover caused negative freeboard and flooding,and then snow ice formation,which contributed 12%–49%to the maximum ice thickness.In early summer,snow cover delayed the onset of ice melting for about one month,while the melting of snow cover led to the formation of superimposed ice,accounting for 5%–10%of the ice thickness.Internal ice melting was a significant contributor in summer whether snow cover existed or not,accounting for 35%–56%of the total summer ice loss.The multi-year ice(MYI)simulations suggested that when snow-covered ice persisted from FYI to the 10th MYI,winter congelation ice percentage decreased from 80%to 44%(snow ice and superimposed ice increased),while the contribution of internal ice melting in the summer decreased from 45%to 5%(bottom ice melting dominated).