HR: 0800h
AN: GC11A-0128    [Abstracts]
TI: More than Just Hurricanes: The Atlantic Multidecadal Oscillation and Extreme Precipitation over the US and Mexico from August to October
AU: * Curtis, S
EM: curtisw@ecu.edu
AF: East Carolina University, Department of Geography Brewster A232, Greenville, NC 27858, United States
AB: The tail of the distribution of daily precipitation for August-September-October was examined over the United States and Mexico in relation to the Atlantic Multidecadal Oscillation (AMO). As expected from previous studies linking the AMO to hurricane activity, Florida and the coastal Southeast U.S. showed an increase in precipitation intensity when the Atlantic was in a warm phase (AMO+). Also during AMO+ Northwest Mexico was dry and exhibited a reduction of extreme events and the Mid-Atlantic Appalachian Mountains showed evidence of an increase in heavy precipitation compared to when the Atlantic was cool. It is proposed that the aforementioned decadal variations in extreme rainfall are forced by changes in the large-scale surface winds and air temperature in conjunction with the AMO. Namely, an anomalous cyclonic circulation is observed off the Southeast coast, leading to a reduction of moisture flux into the decaying North American monsoon, and an increase in moisture flux into the Mid-Atlantic. Further, the Mid-Atlantic shows a relatively strong increase in the mid-tropospheric lapse rate. Thus, the unique combination of low-level humidity, potential instability, and elevated topography are consistent with an enhanced risk of intense rainfall during AMO+.
UR: http://dx.doi.org/10.1007/s00382- 007-0295-0
DE: 1620 Climate dynamics (0429, 3309)
DE: 1807 Climate impacts
DE: 1817 Extreme events
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3354 Precipitation (1854)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting