东北典型林区雪深反演算法的验证与分析

摘要 积雪对自然环境和人类活动都有极其重要的影响。积雪参数（雪面积、雪深和雪水当量）反演对水文模型和气候变化研究有着实际的意义。然而，目前森林区的雪深遥感反演精度一直有待于进一步提高。东北地区是我国最大的天然林区和重要的季节性积雪区之一，本文利用FY3B卫星微波成像仪（MWRI）L1级亮温数据和L2级雪水当量数据，以及东北典型林区野外实测雪深数据，对Chang算法、NASA 96算法和FY3B雪深业务化反演算法进行了验证与分析。结果表明：在东北典型林区的雪深反演中，Chang算法和NASA 96算法反演的雪深波动都比较大，当森林覆盖度f≤0.6时，NASA 96算法表现比较好，均方根误差值在3种算法中较小，但当f >0.6时，NASA 96算法失真严重。当考虑纯森林像元（f=1）时，Chang算法低估了雪深47%。当f≤0.3时，FY3B业务化算法始终优于Chang算法。整体上，FY3B业务化算法相对稳定，具有较高的精度。

关键词： 积雪   微波遥感   雪深反演   FY3B-MWRI 

Abstract： Snow cover is one of the active components of the cryosphere. Snow cover has a very important impact on the natural environment and human activities. Snow parameters (snow area, snow depth and snow water equivalent) inversion has practical significance to hydrological models and climate change research. However, the accuracy of snow depth inversion of remote sensing in the forest area should be further improved at present. Northeast is one of China's largest natural forest areas and important seasonal snow areas. This paper used L1 level brightness temperature data and L2 level snow water equivalent data of Microwave Radiation Imager (MWRI) mounted on FY3B satellite, and used field snow depth data in Northeast typical forest regions. Chang algorithm, NASA 96 algorithm and FY3B operational inversion algorithm were validated and analyzed. The results showed that, in Northeast typical forest regions, the retrieved snow depth of Chang algorithm and NASA 96 algorithm had large fluctuations. The performance of NASA 96 algorithm was better than Chang algorithm and FY3B operational inversion algorithm when fractional forest cover (f) was 0.6 or less, because the root mean square error value of NASA 96 algorithm was smaller than the other two algorithms. However, NASA96 algorithm had serious distortion when f was bigger than 0.6. Considering the pure forest pixel (f=1), Chang algorithm underestimated the snow depth of 47%. When f was 0.3 or less, FY3B operational inversion algorithm is better than Chang algorithm. On the whole, FY3B operational algorithm was relatively stable, and FY3B operational algorithm had higher accuracy compared with Chang algorithm and NASA 96 algorithm.

Keywords： snow cover   microwave remote sensing   snow depth inversion   FY3B-MWRI