Tibet Institute of Plateau Atmospheric and Environmental Sciences, Lhasa, Tibet 850000, China;
Meteorolgical Bureau of Nagqu, Nagqu, Tibet 852000, China;
Department of Geography, University of Colorado, Boulder, Colorado 80309, U.S.A;
Meteorological Bureau of Shannan, Tsetang, Tibet 856000, China;
Tibet Institute of Plateau Atmospheric and Environmental Sciences, Lhasa, Tibet 850000, China;