基于FY-3微波成像仪的长时间序列高空间分辨率土壤水分反演算法机理研究

长时间序列高分辨率的土壤水分信息对洪涝干旱监测、农作物估产、水文建模等有着重要意义。风云三号卫星（FY-3B/C/D）可提供被动微波土壤水分产品，但由于X波段对地表的穿透能力有限，其土壤水分产品精度在植被区还有待进一步提高。此外，FY-3土壤水分产品的空间分辨率为25km，难以满足区域尺度对高空间分辨率的应用需求，限制了FY-3土壤水分产品的推广使用。L波段微波传感器在反演土壤水分中具有较大的潜力与应用前景。为了更好的推广国产卫星数据的使用，提高国产卫星数据的应用潜力，本项目拟通过微波机理模型分析，结合L波段SMAP卫星反演土壤水分的优势，校正和改进FY-3被动微波土壤水分反演算法，进一步提高FY-3土壤水分反演精度。综合利用光学/热红外遥感数据的高空间分辨率和被动微波数据不受云干扰的特点，发展时空连续的FY-3土壤水分降尺度算法，提高算法适用性，为高分辨率土壤水分应用需求提供数据支撑。

Long-term and high-resolution soil moisture information is of great significance for flood forecasting, drought monitoring, agriculture yield assessment and hydrological modeling. FY-3B/C/D can provide passive microwave soil moisture products. However, due to the limited penetration of X-band to the surface, the accuracy of soil moisture products needs to be further improved in vegetation areas. Moreover, the spatial resolution of FY-3 passive microwave soil moisture products is coarse with 25km and it is difficult to meet the application requirements of high spatial resolution at the regional scale, which limits the popularization and use of FY-3 soil moisture products. L-band microwave sensors have greater potential and application prospects than C and X-band microwave sensors in soil moisture retrieval. In order to better promote the use of domestic satellite data and improve the application potential of domestic satellite data, this project mainly focuses on FY-3 microwave radiometer imager to carry out the research on the mechanism of long-term and high-resolution soil moisture retrieval algorithm. Based on the analysis of the microwave mechanism model, the FY-3 passive microwave soil moisture retrieval algorithm was corrected and improved by the L-band SMAP passive microwave data, which further improve the accuracy of FY-3 soil moisture product. In addition, the project plans to develop FY-3 soil moisture downscaling algorithm with spatial-temporal continuity by making comprehensive use of the high spatial resolution of optical / thermal infrared remote sensing data and the characteristics of passive microwave data free from cloud interference. This method can improve the feasibility and applicability of the soil moisture downscaling algorithm and provide more accurate data support for the application requirements of long-term and high-spatial resolution soil moisture.