• drought index;
  • PDSI;
  • soil moisture;
  • soil water index (SWI);
  • regional climate models (RCMs);
  • Greece


This paper presents a framework for making use of drought indices in climate change impact assessment studies. To achieve this goal: (1) linear relationships between drought indices and satellite soil moisture information, derived from the ERS scatterometer [Soil Water Index, (SWI)] for the years 1992–2000, are developed by employing [analysis of covariance (ANCOVA)] and (2) the vulnerability of soil water content to climate change is assessed using regional climate model (RCM) projections. Several drought indices are evaluated for their abilities to monitor SWI, on a monthly basis, at nine locations in Greece. The original Palmer Drought Severity Index (Orig-PDSI) and its self-calibrated version (SC-PDSI) correlated best with SWI in three stations each and precipitation in two. The degree of agreement, however, varies substantially among the sites. Seasonality has a significant effect on the relationship between the SWI and the two aforementioned drought indices (Orig-PDSI, SC-PDSI), presenting a bimodal pattern that fluctuates markedly during the year. ANCOVA has proved to be a useful method for measuring the agreement between SWI and the drought indices (r2 ranged from 46.2% to 79.9%), implying that drought indices can be an important information source for detecting and monitoring drought. 11 different RCM runs are compared for their abilities to reproduce present climate mean and variability of temperature and precipitation. Orig-PDSI is not sensitive to the much warmer future climate change scenarios constructed and, therefore, is not suggested for climate change impacts assessment studies. SC-PDSI, on the other hand, has the potential to be used; however, its responses depend on the time period on which the climate characteristics and duration factors are computed from. Copyright © 2009 Royal Meteorological Society