A global perspective on propagation from meteorological drought to hydrological drought during 1902–2014

Meteorological drought is generally regarded as the cause of other types of droughts. This study firstly analyzed the characteristics of meteorological drought and hydrological drought in different climate regions all over the world during a long time period (1902–2014); then, the maximum Pearson correlation coefficients (MPCC) of meteorological drought and hydrological drought at different time scales were calculated to determine the drought response time (DRT) in each climate region. The results revealed that: 1) meteorological drought in most climate regions intensified during 1902–1958 but showed a wetting trend during 1959–2014. Compared with the characteristics of meteorological drought, the change of hydrological drought was slightly different. Hydrological drought weakened during 1902–1958 but intensified slightly during 1959–2014; however, the magnitude of the changing rate was relatively small. 2) The drought response relationship in the Cf (i.e., continental wet warm) climate region was the strongest, and that in the E (i.e., polar) climate region was the weakest. 3) Globally, the DRTs in various climate regions were mainly 5–10 months, which were mainly related to the climate type. The outcomes of this study can provide a reference for further revealing the propagation mechanism from meteorological drought to hydrological drought in different climate regions.