Bias correction of the observed daily precipitation and re‐division of climatic zones in China

Abstract

Using accurate precipitation data is critical to climate and hydrology research, but current studies have found that the precipitation measured by various standard precipitation gauges (P m) is much smaller than actual precipitation and there is a necessity to conduct bias correction before using the gauge‐measured precipitation (P m) data. Using the daily P m, wind speed and temperature data from 553 weather stations in China over 1961–2015, the wind‐induced error ( ∆PDL), trace precipitation (ΔP t) and wetting loss (ΔP w) and the corrected precipitation (P c) were systematically estimated. Consequently, the originally P m‐based climate zone division changed after the precipitation bias correction. The climate zone re‐division was conducted using four P c‐based indices, that is, annual mean precipitation Erinc's index I m, Sahin's index Ish and the United Nations Environment Programme (UNEP) aridity index I A. The results showed that annual mean correction amounts () over 1961–2015 varied between 40.5 and 600.2 mm with the average value of 146.2 mm in China. The ranges of annual mean values of was 11.6–35.3 mm with an average of 24.8 mm, of was 3.6–74.2 mm with an average of 34.07 mm and of was 1.4–525.7 mm with an average of 87.3 mm, respectively. The spatial distribution of decreased from the northwest to the southeast. Annual was generally smaller than 100 mm in northwestern China, but greater than 150 mm in southeastern China. By climate zone re‐division, the areas of severe arid decreased but the areas of severe humid areas increased, which indicated that actual climate conditions of China should be wetter than present assessment results. In conclusion, the bias correction indicated that a corrected climate zone division should be referred in future climatic change research.