Changing structure of wet periods across southwest China during 1961-2012

Using homogenized daily precipitation observations during 1961 to 2012, changes in duration-based structure of precipitation over southwest China under drought conditions were investigated. The results reveal a distinct regrouping of wet periods of different length. Wet days and precipitation related to long wet periods (>3 d) decreased significantly. Such decreases resulted in significantly fewer fractional contributions of long wet periods to total wet days and annual precipitation totals. In contrast, contributions from short wet periods (<3 d) showed significant ascending trends. Substantial decreases in precipitation of long wet periods after 2000 accounted for most reductions in annual precipitation totals and resultant drought tendency. A more specific analysis on seasonal timescales highlights the significance of changes in autumn precipitation structure in causing the drying tendency across southwest China.