考虑气压的晴空大气下行长波辐射参数化方案及其适用性分析

基于Prata晴空大气下行长波辐射参数化方案,针对其在高原地区及可降水量较小地区理论精度较差的缺点,考虑不同高度的大气柱发射的长波辐射量不同,提出了三种考虑气压的大气下行长波辐射参数化方案,通过全球ERA-5再分析数据进行最小二乘拟合确定经验常数并在全球不同区域对其适用性进行了分析.模拟结果表明,考虑气压的参数化方案有...

Parameterizations of Downward Longwave Radiation in Clear Sky Considering Air Pressure and Their Applicability Analysis

Based on Prata parameterization of clear sky downward longwave radiation and in view of its poor theoretical accuracy in plateau areas and areas with small precipitable water vapor,three new parameterizations of clear sky downward longwave radiation are proposed in this paper,in which air pressure is considered because longwave radiation from different length of atmosphere column is different.Empirical constants are obtained by least square fitting of global ERA-5 reanalysis data and their applicability is analyzed in different regions of the world.The simulation results show that parameterizations with consideration of air pressure can effectively improve the convergence of atmospheric emissivity of Prata scheme when the precipitable water vapor can be reduced.The mean bias errors and the root mean square errors of the simulation values of the downward longwave radiation of the new schemes in Amdo Area and San Luis from the observation values are obviously smaller than that of Prata’s parameterization scheme.Compared with Prata’s scheme,the simulation accuracies of the new schemes are improved and the applicabilities are better.