Kropacek, J*; Feng, C; Alle, M; Kang, S; Hochschild, V: Analysis of snow distribution in the Nam Co basin on the Tibetan Plateau from MODIS data
Vortrag, Cryospheric change and its influences, Lijiang, China: 12.08.2010 - 14.08.2010

Snow cover distribution in Nam Co Basin in central part of the Tibetan Plateau was analyzed using MODIS snow product. MODIS (Moderate Resolution Imaging Spectroradiometer) is an optical remote sensing instrument aboard the Terra and Aqua satellites. We developed a comprehensive technique for the visualization of the annual snow cover distribution. This method is based on grouping of 8-day composite snow-cover data into three distinct seasons which are then represented in RGB display. The period of dominant snow cover for each pixel is given by color shade and the duration of the snow cover by the image intensity. The RGB syntheses were generated for the Nam Co Basin for each year in the period 2002 - 2009. Data from both MODIS/Terra (morning flyover) and MODIS/Aqua (afternoon flyover) have been used. The differences between the two resulting sets of snow RGB composites can be attributed to snow and cloud cover dynamics between Terra and Aqua acquisitions. Two seasonal effects on the snow cover distribution were analyzed: summer monsoon and ‘lake effect’, which is a snow fall induced by passing of dry and cold westerlies over the lake surface during winter months. The extent of these two effects were quantified by segmentation of the RGB images. Inter-annual changes of permanent snow cover have also been analyzed. The curve of average snow extent during the year has been calculated directly from 8-day composite snow-cover data for the examined period of 8 years and matches well with ground measurements. The presented method of visualization of the snow cover distribution enables examination of various factors which influence the snow cover in an effective and straightforward way. This method can provide valuable area wide information, especially in the regions with little or no ground data.

Letzte Änderung 17.02.2011