关键词: 关键词：青海高原, 极端气温指数, 时空变化, 海拔效应, 纬度效应

Abstract: Based on the daily maximum and minimum temperature data from 49 observation stations over Qinghai plateau during 1961-2018, the eight extreme temperature indices were slected by using methods of linear regression, Mann-Kendall test, time scales separation and correlation analysis, and the spatiotemporal variations of extreme temperature indices over Qinghai plateau were analyzed. The results are as follows: (1) The extreme temperature warm indices had significant rising trends, while the extreme temperature cold indices decreased significantly. The indices in nights became warming faster than indices in daytime. (2) The abrupt change points for the warm days (TX90P), cold days (TX10P), warm spell duration (WSDI), the minimum value of daily maximum temperature (TXN) and the maximum value of daily minimum temperature (TNX) occurred before and after 1996. (3) There were 3 a, 5-6 a, 10-15 a, 24-31 a or longer quasi-cycle oscillations for extreme temperature indices during 1961-2018. Among them, the 3-year quasi-cycle oscillation was most significant, especially for WSDI and TXN that the amplitude of 3-year time-scale oscillation occupied a dominant position and the contribution rate to raw time series was above 50%. (4) The extreme warm (cold) indices increased (decreased) at the fastest rate in the Qaidam Basin and the eastern agricultural region. (5) The absolute values for most extreme temperature indices trends accelerated from high to low elevations and from low to high latitudes.

Key words: Key words: Qinghai plateau, extreme temperature indices, spatiotemporal variations, elevation effect, latitude effect