Summary: | This study analyzes periodic variations in the climate of the mid-Atlantic Region over the last 100 years and uses general circulation models (GCMs) to project major climate trends for the next hundred years. Historical data include the Palmer Drought Severity Index (PDSI) for the Susquehanna and Potomac River basins, as well as the Southern Oscillation Index (SOI) and North Atlantic Oscillation (NAO). NAO data include indices determined from surface climate data and tree-ring reconstructions. These data illustrate substantial seasonal and interannual variability in the PDSI, but a statistically significant trend of increasing moisture conditions during the past century. Co-spectral analyses comparing the time series of the PDSI, SOI, and NAO reaffirm previous findings. El Nino (La Nina) events are associated with wetter (drier) conditions in the Potomac Basin, while positive anomalies of the winter NAO are associated with wetter conditions in both basins. Statistical down scaling applied artificial neural network analysis to the Canadian Climate Centre's GCM to extend these results to the next century.
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