Improvements In The Parameterization Of The Turbulent Heat Flux Exchange Between Atmosphere And Sea Ice In Sea Ice Models

To improve the turbulent heat flux exchange between atmosphere and sea ice,two new parameterizations are incorporated into a sea ice model(CICE6.0)in this study,including a bulk heat flux(BF-SHEBA)parameterization based on the observation from Surface Heat Budget of the Arctic Ocean,and a maximum entropy production(MEP)parameterization.We use BF-SHEBA and MEP to simulate Arctic sea ice for both 1998 and 2015,and evaluate the performance of the two parameterizations.In the first part of the thesis,we use the in-situ observations from first year ice and multiyear ice to evaluate the results of BF-SHEBA and CICE's default parameterization(BF-CICE),the results show that the seasonal cycles of turbulent heat fluxes simulated by BF-SHEBA and BFCICE are similar,but they don't capture the observed evolution of turbulent heat fluxes on first year ice.On multiyear ice,both BF-SHEBA and BF-CICE have warming effect on the surface throughout the period,without simulating the observed cooling effect during the warm season.Moreover,the magnitude of the negative sensible heat flux of BF-CICE is much larger than that of the SHEBA observations during the cold season.The distribution pattern and magnitude of turbulent heat fluxes simulated by BF-SHEBA and BF-CICE are similar and close.And BFSHEBA leads to the sea ice mass budget as close as BF-CICE.In the second part of the thesis,we first assess how well the MEP captures the observed variations of turbulent heat fluxes over Arctic sea ice.It is found that the calculated heat fluxes by the MEP method are in good agreement with in-situ observations after considering the absorption of incoming radiation in a snow/ice surface layer with infinitesimal depth.We then investigate the effects of two different schemes(MEP vs.BF-CICE)in the sea ice model of CICE6 on simulated turbulent heat fluxes and sea ice processes in the Arctic Basin.MEP causes different distribution pattern and magnitude of turbulent heat fluxes from BF-CICE.The results show that the two different schemes give quite different representations of seasonal variations of heat fluxes,particularly for sensible heat fluxes in summer.The heat fluxes simulated by the MEP produce weak cooling effect on the ice surface in summer,whereas the BF-CICE generates a warming effect.As a result,compared to the BF-CICE,the MEP leads to a reduced seasonal cycle of Arctic sea ice mass flux by modulating snow-to-ice conversion,basal ice growth,surface ice melt and basal ice melt.