青藏高原FY-3C卫星积雪产品评估

The evaluation of FY-3C snow products in the Tibetan Plateau

选取2018年10月1日—2019年4月30日作为积雪研究期,利用青藏高原地区118个气象台站的积雪观测数据,对风云三号C星(FY-3C)多仪器融合的雪盖(multi-sensor synergy snow cover,MULSS_SNC)和微波成像仪的雪水当量(microwave radiation imager snow water equivalent,MWRIX_SWE)产品进行评估,以了解产品的区域可靠性。结果表明:MULSS_SNC和MWRIX_SWE雪盖判识准确率分别为87.18%和72.32%,召回率分别为66.67%和49.63%,误判率分别为12.81%和27.68%,漏判率分别为33.33%和50.37%;对于积雪混合像元或积雪深度不足0.5 cm的卫星像元,MULSS_SNC和MWRIX_SWE都倾向于无雪判识,1 cm以下雪盖漏判率高达60%以上;MULSS_SNC在积雪深度达2 cm以上时,召回率可达到89.09%,而MWRIX_SWE产品在积雪深度达5 cm以上时,积雪判识召回率才达到63.37%。MWRIX_SWE反演的青藏高原地区雪深与地面观测值误差很大,不存在线性正相关关系,不建议直接使用。

In order to understand the regional reliability of the Fengyun-3C(FY-3C)satellite snow products,the authors used the snow cover data of 118 meteorological stations in the Tibetan Plateau from October 1,2018 to April 30,2019 to evaluate the snow cover(MULSS_SNC)and snow water equivalent(MWRIX_SWE)products.The results show that,for snow cover pixels of MULSS_SNC and MWRIX_SWE,the accuracy rate is 87.18%and 72.32%respectively,the recall rate is 66.67%and 49.63%respectively,the false rate is 12.81%and 27.68%respectively,and the missing rate is 33.33%and 50.37%respectively.In terms of mixed pixels or pixels with snow depth less than 0.5 cm,both MULSS_SNC and MWRIX_SWE tend to identify with no snow,and the missing rate of snow depth less than 1cm is up to 60%.When the snow depth of MULSS_SNC is more than 2cm,the recall rate can reach 89.09%.However,for MWRIX_SWE,only when the snow depth is more than 5cm can the snow recall rate reach 63.37%.The snow depth in the Tibetan Plateau from MWRIX_SWE has a large error with ground observations,and there is no linear positive correlation,so it is not recommended to use it directly.