Spatiotemporal Variation in Precipitation over Gansu Province from 1961 to 2018

Abstract

【Background】 Spatiotemporal variation in precipitation is the consequence of a combined impact of regional climate and ecological environment. Global climate change over the past few decades has resulted in a change in precipitation pattern in many regions including Gansu, a province in China characterized by co-existence of arid climate in the west, monsoon climate in the east and alpine climate in the Qinghai-Tibet plateau. This combination makes the ecological and environment systems in Gansu fragile and susceptible to climate change. 【Objective】 The purpose of this work is to analyze the spatial change in precipitation over the province since 1961 as sell as the underlying mechanisms, especially the impact of global warming and anthropogenic activities. 【Method】 Precipitation measured from 59 meteorological stations from 1961 to 2018 across the province was analyzed using the PCI index, the wavelet analysis, MK test and other methods, from which we calculated its characteristics including period of precipitation, abnormal changes as well as trends in its spatiotemporal variation using the sliding t test. 【Result】 The annual precipitation decreased from the east to the west across the province. The intra-annual variation in the precipitation had increased from 1961 to 2018. We identified five periods in the precipitation: 28 years, 22 years, 12 years and 5 years, with the 28 year period most identifiable. Abrupt change in precipitation occurred in the middle 1960s, the early 1970s, the middle 1980s and the early 1990s. Precipitation in the west of the province had been increasing at 0.45 mm/a, while that in the central, south and east parts of the province had been in decline at 0.82 mm/a, 0.81 mm/a and 0.93 mm/a, respectively, until 1990s. But since the 1990s, the precipitation in all regions over the province has been in increase, especially in the east area where the precipitation has been increasing at 3.74 mm/a. 【Conclusion】 The precipitation in Gansu province over the past 60 years showed periodic and had witnessed both extreme rainfalls and droughts. There is a distinguishable difference in temporal change in precipitation between the west and central-east. Since the 1990s, the precipitation in the province has increased significantly. Our results have important implications for improving ecosystem services and alleviating disasters induced by climate changes, apart from providing a baseline database for meteorological, ecohydrological researches in this region and beyond.

Keywords

• gansu province
• precipitation
• spatiotemporal variation
• trend analysis