SPATIAL PATTERN OF TEMPORAL TRENDS IN MOISTURE CONDITIONS IN THE SOUTHEASTERN UNITED-STATES

Palmer's Drought Severity Index (PDSI) is used to represent moisture conditions in the southeastern United States. Temporal trends in annual PDSI for 53 climate divisions in the region are examined for the period 1895 to 1988. Spearman's rank correlation reveals that 19 climate divisions have increasing trends in annual PDSI at the 0.05 significance level, changing towards a wetter condition during the study period. There is no division with a significant decreasing trend. Such temporal changes also display a well-defined spatial pattern. All but one of the divisions with significant increasing trends are located in the southwestern part of the region, centered at Alabama. Climate divisions in Alabama have experienced the most consistent change towards a wetter condition. The increasing rates in the annual PDSI during the study period range from 0.021/year to 0.037/year. Further analysis indicates that the increases in annual PDSI are mostly the result of increasing annual precipitation.