Comparative Study Of Two Land Surface Model In The Hinterland Of Taklimakan Desert

The land surface is a complex system,which is an important way to connect the atmosphere,the hydrosphere and the biosphere.The land surface process is an indispensable link in the process of material and energy exchange of the earth,and the simulation ability of the land surface model directly affects the accuracy of climate simulation and prediction.In recent years,different experimental bases have carried out land surface process research one after another,obtained a large number of observation data,and made a large number of basic observation analysis and parameterization scheme research,which greatly promoted the formation and development of land surface model.Although the study of land surface model is more and more in-depth,the simulation ability of different land surface model is different in different regions.Therefore,it is necessary to combine different land surface models for simulation analysis to evaluate the simulation ability of different land surface models in the area.Based on the observation data of Tazhong Station in Taklimakan Desert,we uses Noah and Noah-MP land surface models to modify the parameters or parameterization schemes of these two land surface models: land surface temperature,surface emissivity,surface albedo,radiative transfer scheme,sensible heat exchange coefficient and soil moisture factor stomatal impedance.Combined with the observation data of Tazhong Station in 2017 and SMAP satellite data,the simulation capabilities of two land surface models at Tazhong Station are compared and analyzed.It is concluded that in the simulation process of different physical quantities,the simulation capabilities of Noah and Noah-MP land surface models are different.The main conclusions are as follows:(1)Based on the conventional meteorological data measured by the gradient observation system of Tazhong station,the atmospheric forcing data needed by the land surface model are made.In the Noah land surface model,the parameters of land surface temperature and surface albedo are modified from the original default values to303.6909 K and 0.905 respectively.According to the surface albedo,solar altitude angle and soil moisture data of Tazhong station,the two-factor parameterization scheme of surface albedo is calculated.Combined with MOD09 GA data,the estimation equation of wide-band surface albedo is established,and the monthly mean of surface albedo is modified by these two parameterization schemes.In the Noah-MP land surface model,the radiative transfer scheme chooses the full grid two-flow approximation radiative transfer scheme,the sensible heat exchange coefficient chooses the Chen97 parameterization scheme,and the soil water stomatal impedance selects the CLM soil matrix potential scheme.(2)The two land surface models are simulated and compared according to the measured data of Tazhong station.In the comparative analysis of land surface temperature,5cm soil heat flux and net radiation,the simulation ability of Noah land surface model is better than that of Noah-MP land surface model.The simulated values of 0.1m soil temperature of the two land surface models are close to the measured values,but they still need to be further improved.The ability of Noah-MP land surface model to simulate sensible heat flux is better than Noah land surface model.The simulation ability of the two land surface models is different in different weather,and the simulation ability of the land surface model is better in sunny weather.(3)Compared with SMAP satellite,except for land surface temperature,the simulation ability of Noah land surface model is better than that of SMAP satellite data.The ability of Noah-MP land surface model to simulate sensible heat flux and net radiation is better than that of SMAP satellite data.The modification and selection of parameters and parameterization schemes affect the simulation results of the land surface model to some extent.In the 5cm land surface model,the parameters of land surface emissivity,surface albedo and land surface temperature are modified to improve the ability of the land surface model to simulate land surface temperature,5cm soil heat flux and net radiation.In the Noah-MP land surface model,the sensible heat exchange coefficient Chen97 parameterization scheme is used to improve the ability of the land surface model to simulate the sensible heat flux.In the two land surface models,the parameter of soil thermal conductivity is not modified,and the simulation accuracy of 0.1m soil temperature needs to be further improved.