微波辐射计反演大气折射率剖面技术研究

Technology for retrieving atmospheric refractivity profiles using radiometer

温度变化引起的干空气和水汽对23.8GHz和31.65GHz双通道微波辐射计的观测亮温变化的贡献表明,干空气对观测亮温的变化可以忽略。在此基础上,提出了将折射率的干项和湿项分别反演的方法,并且将径向基神经网络(RBF网络)方法应用于折射率剖面反演中。基于青岛历史探空数据和实验数据,对线性回归、非线性回归和Hopfield模型反演折射率干项剖面的精度进行了比较,并对利用线性回归、非线性回归、BP网络和RBF网络方法反演折射率湿项剖面的精度进行分析,结果表明:反演折射率干项和湿项剖面分别采用线性回归方法和RBF网络方法可提高反演精度。

By analyzing the variation of brightness temperature induced by water vapor and dry air due to change of temperature for the ground-based dual-channel radiometer operating at 23.8 GHz and 31.65 GHz ,it is indicated that variation of brightness temperature induced by dry air can be ignored. The method to retrieve dry and wet refractivity profiles respectively is proposed,and the radial basis function method (RBF network) is first applied to retrieve refractivity profile. Based on historical radiosonde data,t...