A Study Of The Near-surface Atmospheric Water Vapor In Qilian Mountains Region Based On MODIS And NCEP/NCAR Data

Water vapor is an important indicator for evaluating cloud water resources.Research on water vapor changes is of great significance to the nature of aerosols,radiation equilibrium,moisture cycle,energy transportation and global climate change.The use of satellite remote sensing atmospheric water vapor content technology and NCEP/NCAR reanalysis data have solved the problem of water vapor data record discontinuities to some extent,and it has been widely used in the estimation of water vapor.The Qilian Mountain region is one of the worst water shortages in China.In order to solve the problem of regional water shortages,scientific researchers have conducted many artificial precipitation tests.The content of their studies face the scientific and technological needs of China's water supply security.The near-surface atmospheric vapor analysis carried out in this paper in the Qilian Mountains provide support for the near-surface artificial rainfall and snowfall technoligy.Combining the advantages of MODIS data and NCEP/NCAR reanalysis data,this paper presents an innovative approach that based on the inversion of total column atmospheric water vapor content using data from MODIS,combined with data from NCEP/NCAR to calculate nearsurface atmospheric water vapor content.The calculation results have the advantages of highresolution and continuity.This method overcomes the shortcomings that water vapor pressure from the meteorological station was used to calculate the near-surface atmospheric vapor content in the past,so that the station has a greater impact on the results and the obtained vapor data are not continuous.The main research work of this paper are as follows:1)Bying using the three-channel ratio inversion model to derive the total column water vapor content based on MODIS data.2)Analyzing specific humidity data and the local pressure from NCEP/NCAR,the research area is divided into mountain area and placid area.This paper defines the altitude layer of nearsurface and calculate the subsurface atmospheric water vapor of mountain areaand placid area.3)The near-surface atmospheric water vapor of Qilian mountain area were got by calculating the total column water vapor from MODIS and the subsurface atmospheric water vapor from NCEP/NCAR.The results of the surface atmospheric water vapor and the slope factor(slope,aspect,landform type)based on DEM were analyzed by correlation.