地球物理模式函数（GMF）在星载微波散射计海面风场反演中具有关键作用。本文以C波段MetOp/ASCAT散射计风场数据为参考数据，通过改进现有Ku波段NSCAT-4 GMF中后向散射系数对海面风速和风向的依赖关系，以及增加海表温度（SST）因子项，构建了适用于HY-2卫星微波散射计海面风场反演的NSCAT-5.HY-2 GMF。研究结果表明，相比NSCAT-4 GMF，采用NSCAT-5.HY-2 GMF反演得到的HY-2散射计海面风速与ASCAT散射计风速的一致性提高了约11%，特别是风速反演误差不再依赖于SST变化、不再呈现显著经向分布特点。本论文研究结果对进一步提升国内外其他Ku波段星载微波散射计数据的海面风场遥感应用具有重要参考价值。

(Objective) The Geophysical model function (GMF) is necessarily important in space-born scatterometer wind retrieval data processing, and is a main factor that dominates the error characteristics of retrieved winds. In this study, a new Ku-band GMF (named NSCAT-5.HY-2), which includes sea surface temperature (SST) dependence, is developed for improved HY-2 satellite scatterometer (HSCAT) wind retrieval. Based on the existing NSCAT-4 GMF, the dependence of σ0 on wind speed and direction will be refined, and then add the dependence of σ0 on SST. (Method) It has been shown that sea surface winds from the C-band advanced scatterometer (ASCAT) onboard the MetOp-B and C satellites are of good quality and have no dependence on SST; thus the ASCAT winds are used as reference for developing the NSCAT-5.HY-2 GMF. Since the HY-2C and HY-2D are in non-sun-synchronous orbits with 66.0° inclination and their equator crossing times shift each orbit. As such, HY-2C or HY-2D scatterometer represents a unique opportunity to acquire closely collocated HSCAT and ASCAT scatterometer winds at different times of day. In this study, wind vector cells (WVCs) between HSCAT and ASCAT are matched by limiting spatial distance within 25/√2 km, and time differences within 45 min. The close collocations of HSCAT and ASCAT winds allow accurate attribution of the different correlated residual geophysical effects of wind speed bias and distribution, SST, sea state, rain, wind variability, and geographical sampling biases. Here, we explore the opportunity of close collocations of HSCAT-C and ASCAT, and develop an SST-dependent Ku-band GMF for HY-2 scatterometers. (Result) Utilizing the probability density function (PDF) of ASCAT wind speed as reference, the wind speed corrections as a function of wind speed can be calculated by using the cumulative distribution function (CDF) matching technique, which in principle aligning the PDF of HSCAT wind speeds with the referenced PDF. For wind direction modulations, five terms of the Fourier series are used and the harmonic coefficients are derived using ASCAT wind direction as reference. The variations of σ0 as a function of SST are given as a polynomial expansion for each given wind speed, and the polynomial coefficients are obtained from both observed and simulated radar cross sections, using closely collocated ASCAT winds, of either vertical or horizontal polarizations. (Conclusion) Validation of the new HSCAT wind products retrieved using NSCAT-5.HY-2 GMF shows clear improvements over those obtained with NSCAT-4 GMF. Especially, the consistency between HSCAT and ASCAT winds is much improved by at least 10%, and wind speed differences no longer depend on SST.