Changes in Precipitation and Drought Extremes over the Past Half Century in China

Abstract

Changes in climate extremes have become a hot issue in the research field of climate change recently. Many studies have reported that climate extremes have occurred more frequently and with increasing intensity in recent decades. In this study, thresholds of precipitation and drought extremes were determined by the cumulative distribution function, and their spatiotemporal changes over the past half-century in China were analyzed by relative change rate. The results show that: (1) precipitation extremes increased in all regions except North China, while increasing trends of drought extremes were detected in all regions except Northwest China and the Qing–Tibet Plateau; (2) the maximum change rates in frequency of precipitation extremes were found in Northwest China and the Qing–Tibet Plateau, with values of 16.13% and 8.12%, and the maximum change rates in frequency of drought extremes were in Southwest and Southeast China, whose increases in intensity of drought extremes were also the maximum; (3) variation in precipitation extremes showed a relatively mixed pattern with higher heterogeneity compared to that of drought extremes; and (4) changes in precipitation and drought extremes relate to mid-intensity, lower-intensity, and annual precipitation.

Change-Point Analysis of Precipitation and Drought Extremes in China over the Past 50 Years

“…In the threshold determination of DEs [36], a supposed level of consecutive dry days (CDD) was determined as the DE threshold for each meteorological station. That is, if an observed CDD is longer than the supposed CDD, it can be called a DE event.…”

“…In the past two decades, there have been more and more studies [14,24,27,[30][31][32][33][34][35][43][44][45][46][47][48] in this field, in China since 1999, the researcher Zhai et al [6] published their article about the changes of climate extremes in China. Regionally in precipitation extremes, in Southeast China, an increasing frequency trend was detected [30,32,34,36,45,46], especially in the middle and lower reaches of the Yangtze River [14,30,45] and in the coastal areas [34]. While PEs in Northeast China was also detected a decreasing trend [45,49].…”

“…In Southwest China, a decreasing trend in PEs was reported by Wang et al (2009) [32], while in Hengduan Mountains of this region, Li et al (2011) [46] found a nonsignificant increasing trend for 1960-2008. In North China, PE was identified as a decreasing trend by many researchers [32,36,45], while Li et al (2010) [33] found a not significant increasing trend in Loess Plateau of China. In studies concentrated on DE trends, increasing tendency was reported in North China, Southwest China, and Southeast China, by indices of short or long dry days [44], daily precipitation [24], and consecutive dry days [36].…”

“…In North China, PE was identified as a decreasing trend by many researchers [32,36,45], while Li et al (2010) [33] found a not significant increasing trend in Loess Plateau of China. In studies concentrated on DE trends, increasing tendency was reported in North China, Southwest China, and Southeast China, by indices of short or long dry days [44], daily precipitation [24], and consecutive dry days [36]. However, the DE trend in Northeast China was in dispute, Wang et al (2013) [48] found the consecutive dry days decreased while Liang et al (2016) [49] reported an increase in consecutive dry days.…”

“…More, there were more contributions in regional while less in the whole China. Besides, most of studies were focused on the changing trend while few were focused on the change-point analysis and the concrete change process of the PE and DE series.The objective of this study is: 1) to calculate the accurate change-point years of PEs and DEs at each meteorological station across China, based on the time series of the frequency and intensity of PEs and DEs in our previous paper [36]; 2) to then investigate the spatial distribution of their increasing change-point years of PEs and DEs by dividing the whole China into six climatic regions; and 3) in the end, nine typical stations were selected based on the regions and the spatial distribution pattern of the change-point years to demonstrate the concrete temporal change processes of the frequency and intensity of PEs and DEs by the cumulative deviation. The expected results would provide data for risk management of climate changes.…”