Spatial patterns and possible mechanisms of precipitation changes in
recent decades over the Tibetan Plateau in the context of intense
warming and weakening winds
Abstract
The Tibetan Plateau (TP) significantly affects its surroundings and the
global climate through thermal and dynamic processes. Precipitation is a
key driver of hydrological, meteorological, and ecological processes. In
general, the precipitation over the TP displays a wetting trend over the
past half century, with large spatial heterogeneity. However, the causes
of such spatially variable trends in TP precipitation and the driving
forces have not been well quantified. Here we investigate the spatial
variations in precipitation trends and their possible mechanisms, using
ground-based observations from 132 CMA (China Meteorological
Administration) stations (1970–2016) and CMFD (China Meteorological
Forcing Dataset) reanalysis data (1980–2016) over the TP. The major
findings are: (1) Pronounced spatial patterns of precipitation changes
(increasing on the inner TP and decreasing for regions around the TP)
are observed in both CMA and CMFD data. (2) Maximum precipitation
decreases generally occurred in stations that experienced a
southwesterly daily maximum wind speed (Ws). (3)
Positive correlations between mean precipitation amount and
corresponding temperature (or Ws) are obtained in
directions of maximum precipitation increase (decrease), which are
further verified by the qualitative and quantitative analysis of the
CMFD dataset. Therefore, we suggest that intensified local recycling in
a warming and hydrologically unbalanced environment has led to
precipitation increases on the central TP, whereas precipitation
decreases in areas bordering the TP may be the result of a weakening
Indian monsoon.