Changes in seasonal precipitation of East Central North America with connections to global climate.
2010-10
Loading...
View/Download File
Persistent link to this item
Statistics
View StatisticsJournal Title
Journal ISSN
Volume Title
Title
Changes in seasonal precipitation of East Central North America with connections to global climate.
Authors
Published Date
2010-10
Publisher
Type
Thesis or Dissertation
Abstract
Research on oxygen isotopes in stalagmites collected in West Virginia caves has yielded several new insights into regional climate. Oxygen isotopes most likely represent changes in the mean annual isotopic composition of precipitation, a parameter determined locally by the seasonal distribution of precipitation (Hardt et al., 2010). Holocene samples indicate that summer precipitation represented a greater proportion of annual totals, consistent with lake level results (Shuman and Donnelly, 2006) and climate models (Braconnot et al., 2007; Diffenbaugh et al., 2006). During the Pleistocene, seasonal precipitation varies on precessional timescales, although the phasing appears unusual in that it is in-phase with September insolation rather than June. This offset could be due to several processes, most likely in conjunction with each other. These processes include: changes in Gulf of Mexico sea surface temperatures, partially modulated by glacial meltwater routed through the Mississippi (Oglesby et al., 1989; H Wang et al., 2010); changes in the mean state of the tropical Pacific ocean between to El Nino- and La Nina-like conditions (Timmermann et al., 2007); and a seasonally-lagged sea surface temperature response in the subtropical North Atlantic, which would enhance the anticyclonic circulation of the Bermuda High. These same processes also appear to influence isotopic behavior over the last glacial Termination. During the last glacial maximum, oxygen isotopic composition is enriched, consistent with model results indicating wetter summers near the southern margin of the ice sheet (Bromwich et al., 2005), but inconsistent with a temperature control. Antiphasing in summer precipitation between West Virginia and Florida support a control on seasonal precipitation by changes in the position or size of the Bermuda High (Donders and de Boer et al., 2009). Comparison with speleothems from Northeast Brazil (Cruz et al, 2009) indicates a role for the El Nino Southern Oscillation due to its effect on the position of the Bermuda High (Seager et al., 2005).
Description
University of Minnesota Ph.D. dissertation. October 2010.Major: Geology. Advisor: Dr. R. Lawrence Edwards. 1 computer file (PDF); vi, 166 pages, appendices 1-3.
Related to
Replaces
License
Collections
Series/Report Number
Funding information
Isbn identifier
Doi identifier
Previously Published Citation
Suggested citation
Hardt, Benjamin Fulper. (2010). Changes in seasonal precipitation of East Central North America with connections to global climate.. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/117612.
Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.