The 155 grid point PDSI field was separated into eight relatively
homogenous regions of summer drought through a cluster analysis.
For complete details on the analysis see the full data set description. The data can also be found at that site.
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| Values for 1700 - 1894 are reconstructed.
Data for 1895 to 1978 are instrumental data from Cook et al 1999. |
Click on a region number on the map below to get a PDSI time series for that region, or click on link below to view a time series averaged from the entire grid. |