基于变分法的FY-3C土壤水分产品适用性分析

FY-3C作为我国风云三号首颗业务卫星,其上搭载的微波成像仪(MWRI)可提供全天候土壤水分数据。【目的】获取高质量土壤水分数据可以对合理利用土壤水资源提供参考,为农田干旱监控和预报提供基础参数。【方法】选取山东省农业气象站土壤水分数据对FY-3C土壤水分产品进行检验,为获取更高质量FY-3C土壤水分产品,选用变分订正方法对FY-3C土壤水分产品进行偏差订正。【结果】FY-3C升降轨土壤水分产品与地面站土壤水分相关系数R分别为0.481 6和0.408 2,RMSE分别为0.099 6和0.091 0 cm~3/cm~3。订正后FY-3C升降轨土壤水分产品与地面站土壤水分R分别为0.701 4和0.892 4,RMSE分别为0.021 7和0.011 cm~3/cm~3。对2016年3—4月山东省干旱过程订正前、后FY-3C土壤水分变化情况进行对比,订正后FY-3C土壤水分更准确地反映出此次干旱过程。【结论】FY-3C土壤水分产品可以准确反映土壤水分随时间的变化趋势,订正后FY-3C土壤水分产品与地面站土壤水分间误差减小、相关性提高。

Applicability Analysis of FY-3C's Soil Moisture Based on Variational Correction Method

As the first operational satellite of Fengyun-3 in China, FY-3C can provide all-weather soil moisture data by Microwave Radiation Imager(MWRI).【Objective】Obtaining high-quality soil moisture data can provide reference for rational use of soil water resources and provide basic parameters for farmland drought monitoring and forecasting.【Method】This paper selected the soil moisture data of Shandong Agricultural Meteorological Stations to evaluate the soil moisture products of FY-3C. In order to obtain higher quality FY-3C soil moisture products, this paper selected the variation correction method to correct the deviation of FY-3C's soil moisture products.【Result】The RMSE and R of the FY-3C's ascending and descending pass soil moisture products with in-situ soil moisture data was 0.021 7 and 0.011 cm~3/cm~3, 0.701 4 and 0.892 4 respectively. After correction, the R of FY-3C's soil moisture and in-situ soil moisture was 0.701 4 and 0.892 4 respectively, and the RMSE was 0.021 7 cm~3/cm~3 and 0.011 cm~3/cm~3 respectively. In this paper, the soil moisture changes of FY-3C before and after the revision correction of the drought process in Shandong Province in March-April 2016 were compared. After revision correction, the soil moisture of FY-3C more accurately reflected the drought process.【Conclusion】FY-3C soil moisture products can accurately reflect the trend of soil moisture with time. After correction, the error between FY-3C soil moisture products and ground stations' soil moisture decreases and the R had improved.