HR: 0800h
AN: PP11B-0522    [Abstracts]
TI: Pacific And Atlantic SST Influences On Medieval Drought In North America Simulated By Community Atmospheric Model
AU: * Feng, S
EM: sfeng2@unl.edu
AF: School of Natural Resources, University of Nebraska-Lincoln, 718 Hardin Hall, 3310 Holdrege Street, Lincoln, NE 68583-0987,
AU: Oglesby, R
EM: roglesby2@unl.edu
AF: Department of Geosciences, University of Nebraska-Lincoln, 214 Bessey Hall, Lincoln, NE 68588-0340,
AU: Rowe, C
EM: crowe1@unl.edu
AF: Department of Geosciences, University of Nebraska-Lincoln, 214 Bessey Hall, Lincoln, NE 68588-0340,
AU: Loope, D
EM: dloope1@unl.edu
AF: Department of Geosciences, University of Nebraska-Lincoln, 214 Bessey Hall, Lincoln, NE 68588-0340,
AU: Hu, Q
EM: qhu2@unl.edu
AF: School of Natural Resources, University of Nebraska-Lincoln, 718 Hardin Hall, 3310 Holdrege Street, Lincoln, NE 68583-0987,
AB: Terrestrial late Holocene proxy records suggest that during medieval times (800-1300 AD) North America experienced severe centennial-scale drought. In this study, the Community Atmospheric Model (CAM) is used to investigate the role of sea surface temperatures (SSTs) anomalies from the tropical Pacific and the North Atlantic Ocean on this mega-drought. These anomalies are obtained from proxy reconstructions of SST. Four model experiments with prescribed SST anomalies in the tropical Pacific and/or North Atlantic Ocean were made. The CAM results captured the major dry features that occurred during medieval times in North America. The cold tropical Pacific alone can simulate essentially the entire drought area extent, while the warm North Atlantic alone can simulate the drought in the High Plains and the western U.S. The two working together can explain the severity and longevity of the drought. During the spring and summer rainy season, each model experiment simulated less moisture transport to the High Plains and a 15-40% decrease in rainfall there. The model results also show that changes in North America monsoon are primarily due to SST anomalies in the Atlantic Ocean. The importance of the Atlantic Ocean on medieval drought in North America suggests that attention should be paid not only to the tropical Pacific Ocean, but also to the North Atlantic Ocean in understanding the North America drought variability and predictability, both at present and during the past.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1626 Global climate models (3337, 4928)
DE: 3344 Paleoclimatology (0473, 4900)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting