Changes of temperature and precipitation extremes in a typical arid and semiarid zone: Observations and multi‐model ensemble projections

Abstract

AbstractThe spatiotemporal changes of temperature and precipitation extremes in a typical arid and semiarid zone (Gansu Province, China) were investigated, including the latest observations (1960–2016) and the National Aeronautics and Space Administration Earth Exchange Global Daily Downscaled Projections (NEX‐GDDP) dataset that provides statistically downscaled Coupled Model Inter‐comparison Project Phase 5 (CMIP5) future climate projections (2017–2099) based on the Mann–Kendall test, linear regression, 5‐year smoothed average and Bayesian model average (BMA) methods. The results show the following: (a) Apart from a slight decrease of diurnal temperature range (DTR), other temperature extreme indices presented significant trends over 1960–2016. Annual regional nighttime temperature increased at a faster rate than daytime temperature. In the seasonal series, cool nights (TN10p) and cool days (TX10p) showed significant decreases and warm nights (TN90p) and warm days (TX90p) significantly increased in all seasons. (b) Precipitation extreme indices showed decreasing trends, except for the max 1‐day precipitation (RX1DAY) and simple daily intensity index (SDII) with a weaker coherence of spatial patterns. From the perspective of spatial characteristics, the western area had an increasing trend of total precipitation while the east had a significant decreasing trend. In the seasonal series, a significant increase of RX1DAY and the max 5‐day precipitation (RX5DAY) was found in winter, as compared with spring, summer and autumn. (c) Positive trends in warm indices (i.e., summer days, tropical days, warm nights and warm days) and negative trends in cold indices (i.e., frost days, ice days, cool nights and cool days) can be observed in the 21st century. A slightly decreasing consecutive dry days (CDD), together with obviously increasing heavy precipitation days (R10), extremely wet days (R99p), RX5DAY and SDII, suggests more extreme precipitation for 2017–2099. The results are of practical use in improving regional strategies for water resources and eco‐environment management, especially for arid and semiarid regions.