Spatiotemporal variability of precipitation during 1961-2014 across the Mongolian Plateau

摘要

Precipitation is the dominant factor that controls vegetation growth and land-use practices in the arid and semiarid Mongolian Plateau (MP),so the spatiotemporal heterogeneity of precipitation change has been an important scientific question in the region.This study investigated the spatiotemporal characteristics of annual and seasonal precipitation across the entire MP based on monthly precipitation data from 136 meteorological stations during 1961-2014 by using a modified Mann-Kendall test,Sen's slope,Morlet Wavelet Transform,and geostatistical methods.Results show the following:1) Annual precipitation decreased slightly from 1961 to 2014.Stations with positive and negative trends were 41.9％ and 58.1％,respectively.Significant positive trends were mainly in the southwestern and northeastern regions of the plateau,whereas significant negative trends were in the northern and southeastern regions.2) Precipitation decreased at rates of-5.65 and-0.41 mm/deeade in summer and autumn,respectively,but increased at 1.91 and 0.51 mm/decade in spring and winter.The contribution of spring and winter precipitation to the annual amount increased significantly,but that of summer precipitation decreased significantly.3) A large majority of stations (80.2％) showed decreasing trends in summer,whereas 89.7％ and 83.1％ of stations showed increasing trends in spring and winter.The spatial distribution of trend magnitude in seasonal precipitation amount was strongly heterogeneous.4)By climatic zones,precipitation increased in humid and arid zones,but decreased in a semiarid zone.On the whole,the MP experienced a drying trend,with significant regional differentiation and seasonal variations.