Study on permafrost distribution in Qinghai-Tibet Plateau based on MODIS data

摘要

It's one of the important issues to identify the ground boundary of permafrost in the permafrost study. Mean annual ground temperature (MAGT) is the ground temperature at the depth of zero annual amplitude in permafrost layers and it is one of the main indicators for permafrost division in Qinghai-Tibet Plateau. In this paper selecting Qinghai-Tibet highway as a study area and surface temperature, elevation, equivalent latitude, soil moisture, albedo, normalized difference vegetation index (NDVI) as model factors. According to relativity analysis on MAGT and model factors mentioned above to build a ground temperature retrieval model based on MODIS data. Considering the equivalent latitude in section, the coefficient of determination increased from 0.598 to 0.617 and 0.826, the model stability and prediction is improved. Compared to permafrost map, it is found that the simulated result can effectively describe the distribution features of permafrost along the Qinghai-Tibet highway, only in the middle there are a small number of melting districts. The melting districts are mainly distributed nearby the Tuotuo river, where is a perennial river and has a large flows, appear melting district can be considered reasonable, conform to the actual distribution law of the permafrost. Although there are still some differences in individual areas, it may be improved by increasing sample points.