中国稳定积雪区IMS雪冰产品精度评价

IMS雪冰产品由多种光学与微波传感器数据融合而成，提供北半球每日无云的积雪范围，在积雪遥感研究中具有广阔的前景. 以气象站实测雪深数据为真值，检验了2009-2010年IMS雪冰产品在中国三大稳定积雪区北疆、东北、青藏高原地区每月、积雪季以及全年的误判率、漏判率和总体准确率，并分析了IMS雪冰产品的准确率与雪深之间的关系. 结果显示：IMS雪冰产品的年总体准确率在三大积雪区均超过了92%，积雪季总体准确率均超过了88%，利用IMS雪冰产品监测积雪范围是可靠的. 然而，IMS雪冰产品精度具有区域差异性，北疆地区在1月和2月误判率偏高，青藏高原地区积雪季有严重的漏判现象. IMS雪冰产品的准确率在东北地区和北疆地区随着雪深的增加而升高，当东北地区雪深超过6 cm，北疆地区超过13 cm时，准确率接近100%，但是，青藏高原地区两者基本没有关系. 通过在青藏高原地区与同时相的4景MODIS积雪产品对比分析发现，实际上IMS雪冰产品相对地高估了积雪面积，青藏高原地区漏判率高其原因是IMS对零碎积雪的识别能力不足并且气象站分布不均匀.

Accuracy evaluation of the IMS snow and ice products in stable snow covers regions in China

The interactive multisensor snow and ice mapping system (IMS), which is composed of various optics and microwave sensor data, provides daily cloud-free snow extent of Northern Hemisphere, and shows great prospects in the remote sensing research of snow and ice. Using snow depth data measured at s as true value, snow cover seasonal and annual omission error rates, misjudgment rates and overall accuracy rates of IMS snow and ice products in Northern Xinjiang, Northeast China and Tibetan Plateau were examined monthly from 2009 to 2010, and the relationships between the accuracy rates of IMS products and snow depths in these three stable snow cover regions in China was analyzed. Results indicate that the annual overall accuracy rate of IMS products is over 92%, snow cover season overall accuracy is over 88% in all regions, so it is to monitor snow cover with IMS products. However, the accuracy rate of IMS products varies from region to regions. Omission error in Northern Xinjiang is high during January and February, whereas misjudgment rate is significant in an in snow cover season. The accuracy of IMS products in Northeast China and Northern Xinjiang increases with the adding snow depth, which is close to 100% when snow depth is more than 6 cm and 13 cm, respectively, for these two regions. But it is found that the accuracy of IMS products in the has no any relation with snow depth. A comparative analysis between four IMS and MODIS images of the same phase in Tibetan Plateau shows that IMS products actually overestimate the snow cover area due to its poor identification of fractal snow cover and the uneven distribution of meteorological stations.