全极化微波辐射计参数化前向模型研究

The retrievals of oceanic and atmospheric parameters from fully polarimetric microwave radiometer data depend on an accurate and reliable forward model. The forward model developed based on physical theories could meet the challenge, but its expensive computation makes it is very difficult to achieve near-real-time application. In order to resolving the problem, this project will parameterize the ocean-atmosphere microwave radiative transfer model developed based on related physical theories for rapid computation. The details of our research are as follows, . (a) The numerical models for sea surface microwave emissivity and atmosphere microwave radiative transfer simulation will be developed. The former will be developed and improved based on two-scale theory, research result of calculation method of threshold value of small and large ocean surface wave and analysis of applicability of related empirical models. The later will be performed based on microwave radiative transfer model.. (b) Parameterizing the numerical models founded in our research. For parameterize the numerical model of sea surface microwave emissivity, the structure of parameterized model will be designed based on analysis of numerical simulation, and the mathematical models in which will be developed. Incorporating with the parameterized result of atmosphere microwave radiative transfer simulation, a parameterized forward model for satellite-born fully polarimetric microwave radiometer will be achieved. .The parameterized forward model for fully polarimetric microwave radiometer developed in this project could be applied to on-orbit calibration, retrieval algorithm development et al., and it also meet the needs of near-real-time applications. The achievement of this project would be valuable for related science research of fully polarimetric microwave radiometer.

全极化微波辐射计海洋大气参数的反演依赖于精确可靠的辐射传输模型，即前向模型。基于物理理论的前向模型可靠准确，但其计算速度不能满足近实时反演等应用的需要。本项目拟基于海洋大气微波辐射传输数值模拟建立参数化前向模型的途径解决这一问题。研究包括：(a)利用模拟结果和观测数据对海面长短波划分阈值kd计算方法及相关经验模型适用性进行分析，完善基于双尺度模型的海面全极化微波辐射模拟；基于微波辐射传输理论完成大气微波辐射传输模拟。(b) 通过分析双尺度模型模拟过程，重新构建参数化模型，并设计其中的数学模型，以所有海面参数及入射角作为输入参数实现海面全极化微波辐射数值模拟的参数化；结合大气微波辐射传输模拟的参数化结果，建立新的全极化微波辐射计参数化前向模型。研究成果可应用于星载全极化微波辐射计在轨定标、反演算法开发等研究，同时满足近实时应用的需要，对全极化微波辐射计研究的发展具有一定的科学意义和应用价值。

我国星载全极化微波辐射计已经在设计和研究中，计划于2020年发射。全极化微波辐射计海洋大气参数的反演依赖于精确可靠的辐射传输模型，即前向模型。基于物理理论的前向模型可靠准确，但其计算速度不能满足近实时反演等应用的需要。本项目研究中基于双尺度海面辐射理论实现了海面全极化微波辐射的模拟，并对其进行参数化建立了可以快速计算的参数化海面全极化辐射模型。利用IGRA全球探空数据建立了参数化的大气微波辐射传递模型。研究中利用WindSat数据建立了可以计算海面泡沫全极化微波辐射的统计模型。基于参数化海面全极化辐射模型、大气微波辐射传递模型和海面泡沫辐射模型组成了全极化微波辐射计参数化前向模型。该全极化微波辐射计参数化前向模型可用于星载全极化微波辐射计的观测模拟、亮温数据定标和环境数据产品算法的开发等应用。