Identification and evolution characteristics of drought field in the Pearl River Basin based on REOF-ESMD

Abstract

The traditional drought field studies are inadequate to study drought field characteristics from the perspective of trend and periodicity at the same time, especially to compare the interannual and interdecadal variations of different drought types in the drought field to reveal their similarity and difference patterns. The drought field in Pearl River Basin (PRB) was determined in this paper using the standardized precipitation evapotranspiration index (SPEI) and the empirical orthogonal function (EOF)/rotated empirical orthogonal function (REOF). Periodic characteristics and trend features of the drought field were recognized by extreme-point symmetric mode decomposition (ESMD) and other methods. The results showed that from the perspective of regional characteristics five different spatial modes may be used to categorize the interannual drought field of the PRB; there were interannual cycles associated with the southwest-type drought and the northwest-type drought. The central-south-, north-central- and eastern-type droughts had both interannual and interdecadal cycles; during the study period, the PRB's five types of drought revealed a changing tendency as opposed to a straightforward linear trend; from the interannual variation, the southwest-type drought was consistent with the northwest-type drought prior to 2000, and the north-central-type drought was consistent with the eastern-type drought before 2010. HIGHLIGHTS The spatial characteristics and periodic properties of the watershed were identified.; There are five spatial modes in the Pearl River Basin.; Southwestern and northwestern droughts have interannual cycles.; Five types of droughts in the Pearl River Basin showed a fluctuating trend.; The interannual similarity and variability of the five droughts were studied.;

Keywords

• drought field
• eof/reof
• esmd
• interannual variation
• interdecadal variation
• pearl river basin