To Monitor the Snow Distribution and Influencing Factors in Northern Tibet of China Using SSM/I and NOAA/AVHRR Data

Based on snow depth data of Special Sensor Microwave Imager (SSM/I), snow cover data of NOAA/AVHRR, and snow depth and snow cover data of six weather stations over Northern Tibet Plateau (NTP), we studied snow cover distribution in temporal and spatial scales, and analyzed the influencing factors of snow in the NTP region. The results shown that, in the seasonal cycle, the snow over extent increased rapidly in autumn and winter seasons in the NTP regions over past 40 years. In interannual cycle, the snow cover variation indicated a reducing-increasing -reducing dynamic process in the study area from 1960 to 2003. The wavelet analyses shown that there were oscillation periods of quasi-2~3 yr, quasi-9 yr, quasi-13 yr for temporal distributions of annual cumulative snow cover. In spatial scale, the snow cover (exceeded 15 ten-days over each half-year) mainly occurred in the east part of the NTP region. The greatest variance of snow cover was found in middle and eastern part of the NTP, i.e., Andu and Nierong regions. The analysis of snow cover influencing factors revealed that the temperature and precipitation are the main factors.