基于Landsat-8 OLI的青藏高原IMS 4 km雪冰产品精度评价

Accuracy Assessment of IMS 4 km Snow and Ice Products on the Tibetan Plateau based on Landsat-8 OLI Images

IMS雪冰产品是多源数据的融合产品,提供北半球逐日无云的雪冰覆盖范围,在青藏高原积雪遥感监测和研究中具有广阔的应用前景。利用Landsat-8 OLI积雪覆盖数据对IMS 4km分辨率雪冰产品在青藏高原积雪监测中的精度进行了评估验证。研究结果表明:(1)IMS 4km雪冰产品的平均总精度为76.0%,平均制图和无雪分类精度分别是88.3%和84.9%,利用IMS 4km雪冰产品监测青藏高原积雪具有较好的精度,可以用于青藏高原大尺度积雪覆盖监测;(2)平均多测率为45.4%,漏测率11.7%,IMS 4km雪冰产品高估了实际积雪面积,且积雪面积比例越高,IMS的积雪判识能力越强,同时出现误判几率越高,而漏判几率越低;(3)IMS 4km积雪监测精度在青藏高原总体上呈现海拔较高地段积雪的制图精度较高,随着海拔的降低,积雪监测的漏测和多测呈增加趋势;(4)相比地面观测数据的区域代表性不足问题,基于高分辨率遥感数据的地面积雪分布特征更为详细,得到更为准确可靠的验证结果。

NOAA IMS(Interactive Multisensor Snow and Ice Mapping System)is a blended snow and ice product based on active and passive satellite sensors,ground observation and other auxiliary information,and it is most widely used for large-scale snow cover detection and relevant climate research,providing daily cloudfree snow cover extent in the northern hemisphere and having promising application prospects in snow cover monitoring and research in the Tibetan Plateau(TP).In this study,Landsat-8 OLI images are used to evaluate and validate the accuracy of IMS 4 km-resolution snow and ice product in snow cover monitoring on the TP.The results show that(1)average overall accuracy of IMS 4 km snow and ice products is 76.0%and average produce’s accuracy is 88.3%,which presents that IMS 4 km snow-ice product has good accuracy in snow cover monitoring and can be used for large-scale snow cover detection on the TP.(2)The average commission rate is45.4%and omission rate is 11.7%,which shows that IMS 4 km products overestimate the actual snow area,and the higher the proportion of snow-covered area,the lower the probability of omission rate and the higher the probability of commission rate.(3)The mapping accuracy of IMS 4 km snow cover on the TP generally is higher in the high altitudes,and the commission and omission errors of snow cover monitoring increase with the decrease of elevation.(4)Compared with less regional representativeness of ground observation data,the spatial characteristics of snow cover based on high-resolution remote sensing data are much more detailed,and more accurate verification results can be obtained.The study also shows that overall accuracy and produce’s accuracy based on the reference image instead of classified image can better reflect the overall monitoring accuracy of IMS 4 km snow-cover product on the TP in comparison with other assessment indicators.