Precipitation has been considered to be a critical water source for both human livelihoods and ecosystems in Central Asia. Using observational data and gridded datasets, we studied the regional and seasonal differences of precipitation climate characteristics and variations in precipitation over Central Asia. Using observational data obtained from the China Meteorological Administration, Global Historical Climatology Network (V3.02), we divided Central Asia into four subregions (North, Center, Southwest, and Southeast) based on the differences in seasonal cycles of precipitation. ‘Single peaks’ were detected as types of seasonal cycles over the North and the Southeast, while ‘two peaks’ was the type that occurred in the Southwest. For the Center, the zone of transition between the North and the Southwest, each monthly precipitation value was higher than the Southwest’s and less than the North’s. GPCC (R² of 0.89, RMSE of 64.5 mm/year) was proven to be the most suitable dataset of the four datasets (CRU, GPCC, MERRA, and TRMM) to describe precipitation in Central Asia, based on validation against observational data, and used to detect the spatial and temporal trend of precipitation in Central Asia and four subregions during 1960–2013. No significant trends were observed for annual precipitation in Central Asia, while precipitation in winter displayed a significant increase (0.11 mm/year). Additionally, significantly increasing trends (0.16, 0.27, 0.13, and 0.13 mm/year) were detected in spring, summer, autumn, and winter over the Southeast during 1960–2013.

In this work, we examined spatial and temporal trends for light rain days based on daily precipitation measurements, obtained from 1960 to 2014, from 590 meteorological stations in China. For the analyzed time interval, light rain days over eastern China were determined to decrease by 0.23 days·year⁻¹. In western China, they increased by 0.3 days·year⁻¹. To detect underlying causes for changes in light rain days, lower-tropospheric relative humidity was set as a proxy for light rain days. We then calculated the respective impacts of lower-tropospheric temperature and specific humidity on changes in light rain days. A comparison of the contributions of temperature and specific humidity resulted in the identification of the main cause of changes. Our results indicated that increases in lower-tropospheric temperatures reduced light rain days over the entire country, while variations in specific humidity dominated regional differences for light rain day trends.

In this work, rain totals from 1960–2014, obtained during the warm season (May to October) from 52 meteorological stations, over Xinjiang, China were classified as either light, moderate, or heavy rain in two sub-regions (northern and southern). Spatial and temporal trends for rain amounts and days for the three rain classes were determined. All light, moderate, and heavy rain amounts displayed increasing trends over the two sub-regions. Furthermore, heavy rain amounts contributed the most to changes in total rain amounts. Light rain days in northern Xinjiang significantly decreased, in contrast to increasing light rain days in southern Xinjiang and moderate and heavy rain days within two sub-regions. Results obtained from correlation and relative weights analyses implied that lower-tropospheric specific humidity was the main factor responsible for light rain day trends in Xinjiang. Increasing temperatures were not found to have a significant effect.