Temporal variability of precipitation over the Qinghai‐Tibetan Plateau and its surrounding areas in the last 40 years

Abstract

The Qinghai‐Tibet Plateau (QTP) plays a crucial role in regulating the climate and hydrology over Asia, and studies indicate that the QTP tends to be warm and humid as a whole. Although precipitation variability on the QTP has a great impact on floods, soil erosion, and droughts, it is poorly understood owing to sparse meteorological observations. This study has investigated the temporal variability of precipitation on the QTP and its surrounding areas on different time scales over the past 40 years using the standardized variability index (SVI) based on entropy as well as its changing trends. The results show that the variability of precipitation has different spatial patterns on different time scales. In general, the variability of both the precipitation days and amounts are low in the southeast and northwest corners of the plateau and high in the southwest and north. It was found that the number of light precipitation days in the high vegetation coverage area in the southeastern plateau decreased significantly, but increased greatly in the bare land and sparse vegetation coverage areas in the northern part of the plateau. Such changes are believed to be conducive for ecological restoration. Most importantly, in the southern foothills of the Himalayas, many light precipitation days have turned into moderate and heavy precipitation days, and a significant increase in annual precipitation has also been noted, which are likely to cause natural disasters considering the local topographical conditions, such as landslides and mudslides. Highlights In QTP, SVIME in May is closer to summer mode, indicating monsoon beginning have advanced to May. Extreme precipitation significantly influences precipitation variability. Daily SVIAE decreases in grassland/barren/sparsely vegetated land, good for ecology. Light rain days increased in bare land/sparse vegetation areas, benefiting vegetation restoration. In southern Himalayas, light rain changed to moderate/heavy rain, leading to natural disasters.