Variations and trends of the freezing and thawing index along the Qinghai-Xizang Railway for 1966-2004
1966-2004年青藏铁路沿线年冻结与融化指数的变化趋势

Annual freezing and thawing index of 7 meteorological stations along the Qing-hai-Xizang Railway were calculated based on daily maximum and minimum temperature records for 1966–2004. Trends of annual freezing and thawing index were analyzed using the Mann-Kendall test and a simple linear regression method. The results show that: 1) The mean annual freezing indices range from 95 to 2300°C·d and the mean annual thawing indices range from 630 to 3250°C·d. The mean annual freezing index of the 7 stations exhibited decreasing trends with decreasing rate of 16.6— 59.1°C·d /10a. The mean annual thawing index of these 7 stations showed increasing trends with the related decreasing rate is 19.83–45.6°C·d /10a. 2) The MK trend test indicated the significant decreasing trends (significant at < 0.05 significant level) in the annual freezing index for most stations except for Golmud. The significant increasing trends can be observed in the annual thawing index for 4 stations except Golmud and Tuotuohe. Golmud was the only station with no trends in both annual freezing and annual thawing index. Foundation: Knowledge Innovation Program of Xinjiang Institute of Ecology and Geography, CAS, No.0571041 Author: Jiang Fengqing (1963–), Ph.D and Associate Professor, specialized in regional climatic and environmental changes.