Trends and Possible Causes of Different Levels of Precipitation Variations in China during 1961–2020

Studies have shown that global warming has changed global precipitation patterns, with a general trend of light precipitation and a significantly increasing trend of intense precipitation in some regions. However, more systematic studies are required to examine precipitation variation at different levels, especially on the regional scale. Based on precipitation data from 838 meteorological stations in China, this report investigated the trends of light, moderate-intensity and extreme precipitation in China from 1961 to 2020 and the relationship between their interdecadal component and ocean oscillation factors. The result shows that China’s spatial distribution of precipitation variability varies considerably. Light precipitation predominantly increases in western northwest China and the Qinghai–Tibet Plateau, whereas it decreases substantially in southern China and southwest China. Precipitation of moderate intensity decreases considerably in the eastern part of southwest China and increases in the rest of China. Extreme precipitation increases in most regions, with decreasing trends only in the Beijing–Tianjin–Hebei region and parts of Chongqing. In most regions of China, light precipitation (light rainy days) contributes less to total precipitation than moderate-intensity and extreme precipitation. The contribution of extreme precipitation in each region exhibits an opposite interdecadal variation to the contribution of moderate-intensity precipitation and light precipitation. The changes in the number of light rainy days and moderate-intensity rainy days dominate the changes in total rainy days. Variations in moderate-intensity precipitation and extreme-intensity precipitation dominate variations in total precipitation. Furthermore, on the interdecadal scale, the correlation coefficients between precipitation at different levels and Pacific Interdecadal Oscillation (PDO) in most of China tend to be negative with increasing levels, while those with Atlantic Multidecadal Oscillation (AMO) tend to be positive with increasing levels. During the 1980s and 1990s, the correlation between precipitation at various levels and PDO/AMO in each region underwent abrupt interdecadal changes.