Self-Calibrated Palmer Drought Severity Index (sc-PDSI)
Index name: Self-Calibrated Palmer Drought Severity Index (sc-PDSI).
Ease of use: Yellow.
Origins: Initial work was conducted at the University of Nebraska-Lincoln by Wells et al. in the early 2000s.
Characteristics: Accounts for all the constants contained in the PDSI and includes a methodology in which the constants are calculated dynamically based upon the characteristics present at each station location. The self-calibrating nature of sc-PDSI is developed for each station and changes based upon the climate regime of the location. It has wet and dry scales.
Input parameters: Monthly temperature and precipitation. Information on the water-holding capacity of soils can be used, but defaults are also available. A serially complete record of temperature and precipitation data is required.
Applications: Can be applied to meteorological, agricultural and hydrological drought situations. With the results being tied directly to station location, extreme events are rare, as they are related directly to that station’s information and not a constant.
Strengths: With the calculations for sc-PDSI accounting for each individual location, the index reflects what is happening at each site and allows for more accurate comparisons between regions. Different time steps can be calculated.
Weaknesses: As the methodology is not significantly different from PDSI, it has the same issues in terms of time lag and frozen precipitation and frozen soils.
Resources: The code can be obtained from the National Drought Mitigation Center (NDMC). The National Center for Atmospheric Research (NCAR) has developed the CRU SC-PDSI (Self-Calibrating PDSI) over Europe & North America tool.
Reference: Wells, N., S. Goddard and M.J. Hayes, 2004: A self-calibrating Palmer Drought Severity Index. Journal of Climate, 17: 2335–2351. DOI: 10.1175/1520-0442(2004)017<2335:ASPDSI>2.0.CO;2.