Palmer Drought Severity Index (PDSI)

Dai, A., K. E. Trenberth, and T. Karl, 1998: Global variations in droughts and wet spells: 1900-1995. Geophys. Res. Lett., 25 , 3367-3370.

The Palmer Drought Severity Index (PDSI) is devised by Palmer (1965) to represent the severity of dry and wet spells over the U.S. based on monthly temperature and precipitation data as well as the soil-water holding capacity at that location. These data consist of the monthly PDSI over global land areas from 1860 to 1995 derived using monthly surface air temperature (from Hansen and Lebedeff, 1987 and updates) and precipitation (from Dai et al., 1997) data. Soil-holding capacity was fixed to climatological maps from Webb et al.(1993). More details can be found in Dai et. al. (1998).

The figure below shows the percentage areas in severe drought (PDSI< -3.0,dashed line), severe moisture surplus (PDSI > +3.0, thin solid line), and the sum of the two (thick solid line) over the regions where data are sufficient during the plotted periods (Dai et. el., 1998). The wet area is plotted on the rightside ordinate, while the dry and total are plotted on the leftside ordinate. Variations with periods less than 24 months were filtered out.

The PDSI data (50502Kb binary file) and the associated README file may be obtained from our anonymous ftp site.

Test ASCII files

REFERENCES:

  • Dai, A., I. Fung, and A. D. Del Genio, 1997: Surface observed global land precipitation variations during 1900-1988.
    J. Climate, 10 , 2943-2962.
  • Dai, A., K. E. Trenberth, and T. Karl, 1998: Global variations in droughts and wet spells: 1900-1995. Geophys. Res. Lett., 25 , 3367-3370.
  • Hansen, J. and S. Lebedeff, 1987: Global trends of measured surface air temperature. J. Geophys. Res., 92 , 13345-37.
  • Palmer, W. C, 1965: Meteorological Drought. Res. Paper No.45, 58pp., Dept. of Commerce, Washington, D.C.
  • Webb, R. S., C. E. Rosenzweig, and E. R. Levine, 1993: Specifying land surface characteristics in general circulation models: soil profile dataset and derived water-holding capacities. Global Biogeochem. Cycles, 7 , 97-108.