MODIS和VEGETATION雪盖产品在北疆的验证及比较

雪盖产品的准确性评估对于水文模型中的遥感应用具有重要的意义,利用北疆47个气象站实测雪深资料,并将气象站根据海拔和下垫面进行分类,对我国可使用的3种光学遥感雪盖产品MOD10A1、MOD10A2和VGT-S10雪盖产品进行验证。研究表明,MOD10A1、MOD10A2和VGT-S10雪盖产品识别总体精度分别为91.3%、90.6%和87.9%,3种产品在农田、草地、城镇和建筑用地总体精度更高 |在稀疏灌木林、裸地与稀疏植被识别总体精度较低,特别是在山区,3种产品识别精度均较低,分别为66.3%、75.7%和61.9%。进一步统计3种雪盖产品的错分误差、漏分误差,发现3种产品错分误差都比较小,但在山区站的漏分误差比较严重,分别为32.4%、21.7%和36.3%,3种产品在山区都低估了雪盖面积。3种不同时间分辨率的雪盖产品云影响率分别为61.8%、7.6%和1.8%。最后将MODIS合成与VGT-S10时间分辨率相同的雪盖产品,并对两种产品在积雪积累期和消融期进行相互比较,比较发现MODIS识别精度要优于VGT-S10雪盖产品,3种产品中VGT-S10由于合成天数最多,所以雪盖产品受云的影响最小。

Evaluation and Comparison of MODIS and VEGETATION Snow Cover Products in Northern Xinjiang,China

Snow is an important component of the Earth's surface. The accuracy of satellite-derived snow-cover area products is important for water management and for modeling hydrological and climatic processes. In the paper,the accuracy of MODIS snow cover products (MOD10A1 and MOD102) and VEGETATION snow cover products (VGT-S10 snow cover products) algorithm under varied terrain and land cover types were analyzed using in situ observation data at 47 climatic stations in northern Xinjiang area,China, during the five snow seasons including January 1 to March 31 of 2001 and each November 1 to March 31 of 2001 to 2005. The research result indicates that the overall accuracy of MOD10A1, MOD10A2 and VGT-S10 snow cover products in all climatic stations is high at 91. 3%,90. 6% and 87. 9% respectively. However, the overall accuracy of the snow cover products in mountain regions is low. The snow omission of three products is 32. A,21. 7% and 36. 3% respectively in mountain climatic stations. The cloud limitation ratio of MOD10A1 reaches to 61. 8%,but that of the MOD10A2 and VGT-S10 are only 7. 6% and 1. 8%. The comparison result of user-defined 10-day MODIS products and VGT-S10 products shows that the snow identification ability of MODIS is more accuracy than VGT-S10 snow cover products. However, the VGT-S10 snow cover products are little affected by cloud than MODIS snow cover products.