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利用SSM/I微波亮温数据,结合地面站点实测资料,比较Chang算法和Che算法在前苏联、中国及蒙古境内6种不同积雪类型的反演精度,结果表明:被广泛应用于全球雪深反演的Chang算法低估了前苏联境内雪深7.6cm,相对误差为-24.3%,而分别高估中国及蒙古境内雪深9.2cm与11.4cm,相对误差分别为108.8%和180.9%,区域反演效果很差;针对中国境内积雪的Che算法严重低估前苏联境内雪深,整体低估21.3cm,相对误差为-68.6%,RMSE为31.4cm;在中国及蒙古境内反演效果有所改善。6个积雪类型中,植被较单一,地形较平坦的苔原型积雪和草原型积雪雪深的反演效果较好。随着纬度和积雪深度的增加被动微波雪深反演有由高估变为低估的趋势。Che算法反演的雪深大体以40°N为界,以北表现为低估,以南表现为高估,另一方面,整体上该算法在雪深低于6.7cm时表现为低高估,高于6.7cm表现为低估;因此,全球算法应用到局部地区需要进行修正,不同下垫面性质以和气候条件下形成的积雪的被动微波反演应区别对待。
Using the SSM / I microwave brightness temperature data, combined with the measured data from the ground stations, the retrieval accuracy of Chang and Che algorithms for six different snow types in the former Soviet Union, China and Mongolia was compared. The results show that the method is widely used in global snow depth The inverted Chang algorithm underestimated the snow depth of 7.6 cm and the relative error of -24.3% in the former Soviet Union, while overestimated the snow depths of 9.2cm and 11.4cm in China and Mongolia, respectively, with relative errors of 108.8% and 180.9% respectively. Regional inversion The Che algorithm for snow cover in China severely underestimated the snow depth in the former Soviet Union. The overall underestimation of snow depth was 21.3 cm with a relative error of -68.6% and RMSE of 31.4 cm. The inversion effect in China and Mongolia has been somewhat improved. Among the six types of snow cover, the inversion of tundra-type snow cover and snow depth of grassland type with single vegetation and flat terrain is better. With the increase of latitude and snow depth, passive microwave snow depth inversion tends to underestimate from over-estimation. The snow depth retrieved by Che algorithm is generally bounded by 40 ° N, underestimated in the north and overestimated in the south. On the other hand, the overall snow cover is underestimated when the snow depth is lower than 6.7 cm, Higher than 6.7cm is underestimated; therefore, global algorithms applied to the local area need to be revised, and the properties of different underlying surfaces should be treated differently from the passive microwave inversion of snow formed under climatic conditions.