Coupled patterns of spatiotemporal variability in Northern Hemisphere sea level pressure and conterminous U.S. drought

[1] We apply the multitaper frequency domain–singular value decomposition signal detection method to the investigation of coherent patterns of variation in seasonal Northern Hemisphere sea level pressure and conterminous U.S. summer drought during the period 1895–1995. The analysis identifies statistically significant patterns of spatiotemporal variability on interannual and bidecadal timescales indicative of both cold-season and warm-season atmospheric influences on North American drought patterns. The most robust signal found appears to be associated with the influences of the El Niño–Southern Oscillation (ENSO) on North American summer drought. Evidence is also found to support the existence of a roughly bidecadal drought signal tied to warm-season atmospheric circulation changes. The ‘‘Dust Bowl’’ conditions of the 1930s appear to result from a combination of these bidecadal influences on drought conditions that coincide with a decrease in the amplitude of interannual ENSO-related variability during the 1930s.