关键词: 生长状况, 生长状况

Abstract: For a comprehensive, in-depth understanding of the characteristics and distribution of Tibetan hail trends relevant for the government and society to provide a scientific basis for disaster prevention and mitigation. The author used the method of Empirical Orthogonal Function (EOF), the characteristics of spatial-temporal distribution about hail days were analyzed based on the daily hail records of 38 stations over Tibet during 1981 to 2010. Results showed that hail days over Tibet increased from southeast to northwest part of Tibet, and the area with annual average hail days more than 10 days was distributed in Langkazi and north region of the Tibet Plateau above 4000 m sea level. There were 2 spatial distribution characteristics about hail days: unitary consistency, difference between south and north in Tibet. The hail occurred frequently at 12-21 o’clock, especially during afternoon to dusk and often occurs in June to September especially in summer with 60% hail occurrence, but in winter not enough 1 days in Tibet. The annual hail days decreased significantly with the rate of 7.7 d/10 a.