Surface Roughness In The Naqu Area Of ??the Qinghai-Tibet Plateau And Its Application In Land Surface Models

In this paper,the aerodynamic roughness length of the Nagqu area is calculated by using the Massman model and MODIS satellite data,and the inversion results of the satellite data are verified using the data of the site(Naqu station BJ,Namco station NAMC,NPAM).Then use Noah-MP's regional model HRLDAS,select the appropriate parameterization scheme as the control experiment,analyze the applicability of the model in the Qinghai-Tibet Plateau,and bring the aerodynamic roughness length obtained by satellite inversion into the model to set the sensitivity experiment,simulate A more accurate gas flux has been obtained,which has deepened the understanding of the interaction between the atmosphere and land on the Tibetan Plateau.Summarizes the primary coverage which this article studies as follows to show:(1)According to the characteristics of the aerodynamic roughness length variation inversion of satellite data,the underlying surface is divided into four categories, from large to small,namely urban,lush grassland,sparse grassland and ice and snow.Among them,lush grassland accounts for 62.49%,the aerodynamic roughness length can reach 6cm,sparse grassland accounts for 33.74%,the aerodynamic roughness length can reach up to 4cm,ice and snow account for 3.7%,and the aerodynamic roughness length does not exceed 1cm.(2)The results of the calculation of the aerodynamic roughness length and the measured data of the satellite data inversion are basically the same,which indicates that the overall the aerodynamic roughness length has continued to increase from February to August,and began to decrease after reaching the peak in August,to the next year.The lowest value was reached in February. Comparing the results of the two calculation methods,there is a significant positive correlation,and the satellite inversion results of the site have a good fit with the measured results.Among them,the satellite surface inversion results from February to May,the aerodynamic roughness length growth is slow,and its calculation results are smaller than the actual measurement results.This method can be used to calculate the aerodynamic roughness length results for a region and provide a true value for the model for simulation.(3)The simulation results after selecting the appropriate parameterization scheme show that the simulated sensible heat flux can better reflect the station actual sensible heat flux change during the day,the mode result is slightly larger than the observation result,and the nighttime is higher than the actual sense.The heat flux reaches about 50W/m~2.When simulating the latent heat flux,the simulation results are lower than the station actual latent heat flux during the day,the maximum value is not more than 400W/m~2,and the nighttime latent heat flux is consistent with the actual,all at around 0W/m~2.(4)The accuracy of the atmosphere and land flux simulation can be improved after improving the aerodynamic roughness length in the Nagqu area.After improving the aerodynamic roughness length of the model,the sensible heat flux has a better daytime improvement effect,about 20W/m~2.The night improvement effect is poor,about in 0.15W/m~2.After improving the aerodynamic roughness length in the Nagqu area,the improvement of the latent heat flux is not obvious.There is an improvement of about 15W/m~2 during the day and a poor change of 0.25W/m~2 at night.Through the study of the aerodynamic roughness length,it is beneficial to obtain the surface feature parameter values on the region,provide accurate surface parameters for the model input,improve the simulation level of the model in the Qinghai-Tibet Plateau,and deepen the understanding of the land-atmosphere interaction process.