Temperature Change and Its Elevation Dependency on the Tibetan Plateau and Its Vicinity from 1971 to 2012

Elevation dependency is a focus of global climate change research. The Tibetan Plateau is often called the roof of the world and analyzing the relationship between climate warming and altitudinal variation for this Plateau is of great significance to global climate change research.Based on monthly mean temperature from 123 national meteorological stations across the Tibetan Plateau and surrounding areas from 1971 to 2012,spatio-temporal characteristics of temperature change and elevation dependency were examined using Mann-Kendall(M-K)tests and moving t-tests. We found that annual,seasonal,coldest month and hottest month mean temperatures,for most stations,displayed an increasing tendency. However,the increasing ranges show a very different spatial pattern with strong warming distributed in central,eastern and northeastern regions of the plateau and weak warming in the southeast. Temperature trend coefficients,except for spring,follow an increasing tendency with increasing elevation,especially on the Tibetan Plateau;however,these displayed different patterns at different elevation gradients. In the zone between2 000~3 000 m,the trend coefficients were more sensitive to altitude than for 3 000~4 000m;the trend coefficients above 4000 m displayed a slight decrease with elevation rise. We found a linear relationship between the timing of annual mean temperature abrupt changes and elevation whereby the time of abrupt change was delayed 1.1~1.2 a per 1km increase in elevation. Lastly,trend coefficients for temperature and elevation dependency across the Tibetan Plateau are sensitive to beginning and end dates.