178 A Climate Analysis Of The Great American Dust Bowl 1932–1936

Monday, 7 July 2014
Manuscript (1.5 MB)

The Dust Bowl of the 1930s consisted of a period of extreme drought and dust storms that significantly impacted the ecology and agriculture of the U.S. and Canadian prairies. The antecedent forcings, anthropogenic in nature, occurred during the previous decade in which temperate biome type farming methods were implemented within a grassland type biome ultimately resulting in severe desiccation and erosion of the topsoil due, in part to aeolian processes. At its maximum, the drought area covered 400,000 sq km centered on the Texas panhandle. This anomalous event was, in turn, greatly exacerbated by climatic forcings including a persistently negative PDO in the Pacific basin coupled with an ONI signal in the tropical Pacific resulting in high return frequency La Nina events. The downstream effect (typical of La Nina) resulted in anticyclonic ridging across the eastern Pacific basin and western North America resulting in a poleward displacement of the mean polar and subtropical jet stream positions. Hence associated synoptic scale cyclones coupled with both jet streams shifted to the north of the drought epicenter resulting in extreme negative precipitation anomalies. Additionally, positive SST anomalies in the North Atlantic basin diminished the magnitude of the Azores-Bermuda anticyclone thus precluding the warm, moist anticyclonically curved meridional return flow into the southern Great Plains. Also, positive anomalies within the barometric in the Caribbean basin likely contributed toward the blocking of moist meridional flows into the drought regions. This paper will be an investigation into both synoptic and mesoscale forcings within the context of biospheric interrelationships that will include signals such as the NAO, AO, PNA, MJO and their associated teleconnections, solar variability and their role in what many historians consider to have been one of the greatest agricultural disasters of the modern era.
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