多频率多极化地表辐射参数化模型

发展了针对对地观测系统被动微波辐射计AMSR-E应用的裸露地表辐射模型。首先，利用1993年法国INRA地面试验数据对AIEM在宽波段高频率和大角度的辐射信号模拟能力进行评价。验证结果表明，AIEM模型模拟值与地面实测数据吻合很好，说明AIEM模型能很好模拟宽波段和大角度的辐射信号。在此基础上，用AIEM模型建立了一个针对AMSR-E传感器参数配置．包含各种地表粗糙度和介电特性的裸露地表辐射模拟数据库。利用AIEM模拟数据和地面实测数据对目前人们使用的半经验地表模型进行了比较和分析，发展了多频率多极化的地表辐射参数化模型——Qp模型。该模型中，地表粗糙度对辐射信号的影响通过粗糙度参数Qp来表示。参数Qp可简单表示为均方根高度与相关长度的比值（s／l）。从Qp模型与AIEM模型模拟的发射率比较结果来看，它们之间的绝对误差很小，不超过10^-3因而，本文发展的参数化模型可用作模拟地表辐射的前向模型，如用于估算AMSR-E传感器的亮温值，同时模型的发展有利于提高人们对辐射机制的理解和认识。

A Parameterized Multi-Frequency-Polarization Surface Emission Model

This study develops a parameterized bare surface emission model for the applications in analyses of the passive microwave satellite measurements from the Advanced Microwave Scanning Radiometer-Earth Observing System(AMSR-E).We first evaluated the capability of the Advanced Integral Equation Model(AIEM) in simulating wide band and high incidence surface emission signals in comparison with the INRA's field experimental data obtained in 1993.The evaluation results showed a very good agreement.With the confirmed confidence,we generated a bare surface emission database for a wide range of surface dielectric and roughness properties under AMSR-E sensor configurations using the AIEM model.Through the evaluations of the commonly used semi-empirical models with both the AIEM simulated and the field experimental data,we developed a parameterized multi-frequency-polarization surface emission model-the Q_p model.This model relates the effects of the surface roughness on the emission signals through the roughness variable Q_p at the polarization p.The Q_p can be simply described as a single surface roughness property-the ratio of the surface rms.height and the correlation length.The comparison of the emissivity simulations by the Q_p and AIEM models indicated that the absolute error is extremely small at the magnitude of 10~(-3).The newly developed surface emission model should be very useful in modeling,improving our understanding,analyses,and predictions of the AMSR-E measurements.