基于AMSR-E的北疆地区积雪深度反演

利用北疆地区2007/2008-2009/2010年度积雪季(12月至次年2月)的AMSR-E降轨19 GHz与37 GHz波段的水平极化亮温数据, 结合北疆地区45个气象台站的实测雪深数据, 建立了北疆地区基于AMSR-E亮度温度数据的雪深反演模型, 并对模型的精度进行评价. 结果显示: 雪深在3~10 cm时, 模型反演的雪深值负向平均误差为-5.1 cm, RMSE值为6.1 cm; 雪深在11~30 cm时, 模型反演雪深值的平均误差仅为2.6 cm, RMSE、 正向平均误差、 绝对平均误差均较小; 雪深大于30 cm时, 模型反演的各项误差较大. 用合成方法反演北疆地区2006/2007-2010/2011年度5个积雪季的平均雪深分布和最大雪深分布, 结果显示北疆地区积雪主要分布于北部阿尔泰山和南部天山一带, 其中阿勒泰地区所占比重最大, 中部的准噶尔盆地腹地、 克拉玛依地区雪层较浅.

Snow Depth Retrieval Based on AMSR-E Data in Northern Xinjiang Region, China

Combining brightness temperature data at 19 GHz and 37 GHz vertical and horizontal polarization channel of AMSR-E data and measured snow depth data from 45 meteorological stations in Northern Xinjiang Region in 2007-2009 snow season (December-February), a snow depth retrieval model was established based on AMSR-E brightness temperature data. The accuracy of the model was evaluated. The result shows the negative average error of retrieval snow depth is -5.1 cm and RMSE is only 6.1 cm for snow depth ranging from 3 to 10 cm. When snow depth is between 11 and 30 cm, the average error of retrieval snow depth is 2.6 cm only, and its RMSE, positive average error and absolute average error are all less. When snow depth is larger than 30 cm, the errors of retrieval snow depth are larger. Comparing the retrieval snow depth with the observed data, it is found that the simulations show a great agreement with the observations at meteorological stations in Northern Xinjiang Region. This basically reflects the snow depth distribution in Northern Xinjiang Region. Comparing Chang algorithm with the retrieval model in this study reveals that the latter is superior to the former and can describe snow depth variation characteristics well in Northern Xinjiang Region. Meanwhile, an average snow depth distribution map and a most heavy snow depth map are drawn by using synthetic method from five snow seasons (2006-2010). The maps show that snow cover is mainly distributed in the Altay Mountains in the north and the Tianshan Mountains in the south, with a maximum in the Altay Mountains. The snow cover is thin in the hinterland of Junggar basin and Karamay area.