Abstract
Under the background of global warming, the trends and variabilities of different grades of precipitation have significant effects on the management of regional ecosystems and water resources. Based on a daily precipitation dataset collected from 148 meteorological stations in the Yangtze River Basin from 1960 to 2017, precipitation events were divided into four grades (small, moderate, large, and heavy precipitation events) according to the precipitation intensity to analyze the temporal and spatial change trends of different grades of precipitation amounts and frequencies, and the influence of different grades of precipitation on total precipitation was also discussed in this study. The results revealed that small precipitation amounts over the Yangtze River Basin decreased significantly, with a rate of −1.22%/10a, while heavy precipitation amounts showed a significant increasing trend (4.27%/10a) during the study period. The precipitation frequency of small and total events decreased significantly, with rates of −3.86%/10a and −2.97%/10a, respectively. Regionally, from the upper reaches to the lower reaches of the Yangtze River Basin, the contribution rate of small precipitation amounts and frequencies to the total precipitation gradually decreased, while heavy precipitation amounts and frequencies increased. The different grades of precipitation in region II showed a decreasing trend due to its unique geographical features. Furthermore, a Pearson correlation analysis was used to analyze the response of precipitation to long-term air temperature, demonstrating that small and moderate precipitation amounts and frequencies were mainly negatively correlated with long-term air temperature and that heavy precipitation amounts showed a stronger positive correlation with long-term air temperature (13.35%/K). Based on this, the rate of change in heavy precipitation in the Yangtze River Basin may be higher under the background of climate warming, which will lead to greater risks of extreme floods in the future. Evaluating and predicting the trends of different grades can provide a theoretical reference for agricultural production, flood control, and drought mitigation.
Highlights
In the context of global warming and frequent human activities, a series of changes have taken place in global and local precipitation patterns, resulting in changes in regional and global water cycles [1,2,3]
Our research indicates that small, moderate, and total precipitation amounts and frequencies were mainly negatively correlated with the long-term trend of air temperature, which is consistent with previous studies [30,32]
Ma et al [4] analyzed the dependence of precipitation changes for each grade in China on the global average temperature, and the results showed that the frequency of small rainfall events exhibited large changes per unit of global warming, with a significant sensitivity of −22.38%/K
Summary
In the context of global warming and frequent human activities, a series of changes have taken place in global and local precipitation patterns, resulting in changes in regional and global water cycles [1,2,3]. The precipitation characteristics (amount, frequency, and intensity) of different grades are expected to change [4]. Based on the data of 8326 highquality terrestrial observatories around the world, Westra et al [5] revealed that the trend of annual maximum daily precipitation time series from 1900 to 2009 showed a significant growth trend on a global scale, and nearly two-thirds of the stations showed an increase. Willems [6] observed that the precipitation extremes in Europe have an oscillating behavior on a time scale of several decades. Identifying changes in different grades of precipitation is imperative for exploring water management strategies, agricultural applications, and ecosystem characteristics
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