Parameterization Of Surface Energy Balance In A Typical Katabatic Wind Region,East Antarctica

The ice/snow-air interaction process on the Antarctica ice sheet surface is a key scientific issue which restricts our understanding of the surface mass balance and improvements on polar weather and climate prediction.Therefore,the parameterization of the ice and snow surface energy process in the east Antarctica region can help to predict the climate in Antarctica more accurately and even the global zone,as well as provide more reliable ground verification for satellite products and model evaluation.Based on long-term meteorogical observations and eddy experiment in typical katabatic wind regions,different simulation and calculation methods for key factors in surface energy balance?solar radiation,albedo,longwave radiation,sensible heat and ice/snow heat flux?are evaluated,and the optimal parameterization scheme in our region is also proposed.After that,we simulated each energy balance component,analyzed the varation characteristics and causes of each factor.In the end,we also discussed with other sites in Antarctica.The main conclusions are obtained:1.Parametric simulation of radiation flux show that,in this katabatic region,?1?Crawford and Laevastu schemes are suitable for the solar radiation simulation in clear and all sky,respectively.?2?Greuell scheme performs best in the albedo comparison,but it will be underestimated under the enhanced katabatic wind and low solar altitude in winter.?3?It reveals that the incoming shortwave radiation and net shortwave radiation are generally small due to the overestimation in the weakening effect of some atmospheric components.But the overall measured value is higher than the low altitude area.?4?After fitting coefficient was used to improve the parameterization accuracy,Dilley and Konzelmann schemes are the best performing schemes in the clear sky and all sky,respectively.However,the latter scheme may overestimate the ability of the Antarctic cloud cover to reflect longwave radiation in the case of large cloud cover.?5?Both simulations of longwave radiation show that the radiation is characterized by high summer and low winter.Because of more downward and less upward longwave radiation,net longwave radiation loss is less than at low altitudes,which is closer to the characteristics in inland plateau station.2.The parameterized simulation of turbulent flux show that,?1?We can calculate and obtain the momentum roughness length"_#is 2.1×10*).When the wind direction significantly changes,the presence of satrugi will significantly increase the surface momentum roughness magnitude.?2?Under stable atmospheric conditions,Businger scheme has the smallest overall error.However,Beljaars scheme can significantly reduce the underestimation of turbulence development in strong stable atmospheric conditions,and its physical significance is more reasonable than the former one.As for the unstable atmospheric conditions,the Lettau scheme has the best error performance.?3?Due to the strong cooling effect of ice sheet on air temperature in winter,the combined effect of large-scale pressure gradient and the gravity will lead to an enhanced katabatic wind and an obvious seasonal cycle of wind temperature.?4?The atmosphere in this study area generally transfers heat to the snow surface in the form of sensible heat.The sensible heat flux is higher in winter and lower in summer due to the enhanced gravity wind,the vertical mixing of wind and the heat compensation effect of the energy balance on the snow surface.3.Parameterized simulation of subsurface heat flux show that,?1?The low heat conductivity of snow can delay the variation and limit the amplitude of the snow temperature in the lower layer.From the perspective of snow temperature profile,the subsurface heat flux should be transferred to the snow surface except for November,December and January.?2?The simulations of effective thermal conductivity show that the results of empirical parameterization schemes ranged from 0.22 to 0.49 W?m0)?k0);The results of Fourier fitting phase difference scheme were 0.12 to 0.19 W?m0)?k0).The range of the iterative parameterization scheme is the largest,with the maximum reaching 0.24 W?m0)?k0) and the minimum as low as 0.0019W?m0)?k0).?3?According to the simplified one-dimensional thermal diffusion equation,we compared the simulated 10cm snow temperature with the measured temperature.It indicates that the iterative parameterized method performs best,but different time window periods will also make the simulated snow temperature behave differently.?4?By comparing the scatter plot of temperature variation,it shows that the parameterization scheme mostly overestimates the temperature variation range.The monthly and seasonal scale time window can significantly improve the simulation performance with the lowest error.?5?According to the comparison,the iteration scheme with monthly or seasonal scale window is optimal.When calculating the underground heat flux,it is found that not only the maximum heat flux time will be advanced or delayed,but also the calculated value can be different due to different time scales,which is very important for studies in the key areas of snowmelt.