Figure 2
The 1870-77 Civil War drought. Top left: the tree ring reconstructed Palmer Drought Severity Index (PDSI, a measure of summer drought severity). Top right: the soil moisture anomaly as simulated by the climate model forced by tropical Pacific SSTs alone. Middle row: the observed from rain gauges (left) and modeled (right) global precipitation anomaly. Bottom left: the observed SST anomaly during the drought is shown. Bottom right: the SST anomaly in the POGA-ML model which is the observed SST anomaly in the tropical Pacific and that computed by a simple ocean model elsewhere. Units are mm per month for precipitation and deg C for temperature.