Qinghai-Tibet plateau is the world's highest and largest plateau which is surrounded by massive mountain ranges. There are plenty of lakes and glaciers covering this area, and the variation of lake area is closely related to the regional and global climate changes. This paper presents a method using MODIS observations to quantify lake area in each month in Qinghai-Tibet plateau for 14 years, and then analyzes the change of lake area at both monthly and annually scales. MODIS surface reflectance data (MOD09A1) acquired within the period of each month are retrieved and composited to produce the optimal and cloud-free SR data of the month, which are adopted as the input data. In order to achieve better accuracy on water detection, multiple water indices are combined, and then the DEM and summer season water maps are adopted to remove noisy pixels caused by cloud, shadow, snow and ice. With this approach, the monthly and annually lake area is derived for Qinghai-Tibet plateau from 2000 to 2013.Subsequently,the accuracy of these results are evaluated by correlation coefficient calculated with respect to the artificial interpreted Landsat products assigned as reference for Selin Co lake and Zhuonai lake, respectively. The comparisons show high consistency on both spatial and temporal aspects(R~2 is 0.99 and0.97). Finally, the variation tendency of lakes in Qinghai-Tibet plateau is analyzed, the results show:(1) a stable increase is obvious (R~2 is 0.96) for the lake area during the past 14 years with an average annual increase rate of490.98 km~2a~(-1); (2)monthly increment indicates lake expansion is unlikely due to seasonality in Qinghai-Tibet plateau. Stable increases (R~2> 0.78, increase rate > 400 km~2a~(-1)) are also found in every month of the year except February, March and April.
1.太原理工大学矿业工程学院, 资源与环境信息系统国家重点实验室, 太原, 山西 030024, 中国 2.Global Land Cover Facility, Department of Geographical Sciences, University of Maryland, College Park, MD, 20742, USA 3.中国科学院地理科学与资源研究所, 资源与环境信息系统国家重点实验室, 北京 100101, 中国 4.环境保护部卫星环境应用中心, 北京 100094, 中国 5.太原理工大学矿业工程学院, 太原, 山西 030024, 中国