HR: 09:15h
AN: PP31A-06    [PDF]
TI: Simulated Changes in Extreme Temperature and Precipitation Events at 6 ka
AU: * Diffenbaugh, N S
EM: ndiffenbaugh@es.ucsc.edu
AF: Department of Earth Sciences, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Bell, J L
EM: jbell@es.ucsc.edu
AF: Department of Earth Sciences, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Sloan, L C
EM: lcsloan@es.ucsc.edu
AF: Department of Earth Sciences, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AB: Paleoenviromental archives record a range of information about past environments. Three key influences shaping paleoclimate records at a given time plane are the mean state of the climate system, interannual variability, and the frequency and seasonality of extreme climate events. We have employed a high resolution regional climate model (RCM) to test the sensitivity of extreme climate events to 6 ka orbital forcing, using western North America as a case study. Extreme precipitation and temperature events were defined by the distribution of daily precipitation and temperature values in the control simulation. Simulated anomalies (6 ka - control) in the number of extreme precipitation events per year were positive throughout the RCM domain, as were anomalies in the percent of annual precipitation delivered by extreme precipitation events. These annual-scale positive anomalies in extreme precipitation were driven by changes in the seasonality of extreme precipitation events at 6 ka, with January, October and November showing the greatest positive anomalies in percent of monthly precipitation delivered by extreme precipitation events. The frequency and length of extreme temperature events in the western United States was also sensitive to 6 ka orbital forcing. Positive anomalies in the frequency of extreme maximum daily temperature values occurred inland in the RCM domain, with peak anomalies of 24 days/year centered over the Great Basin. Likewise, the number of days/year in which the maximum daily temperature exceeded $32\deg$C increased over land by 24$%$, with the average heat-wave up to 12 days longer in the 6 ka simulation than in the control simulation. Finally, mean first and last freeze dates were later inland in the 6 ka simulation than in the control simulation.
DE: 1620 Climate dynamics (3309)
DE: 1833 Hydroclimatology
DE: 3309 Climatology (1620)
DE: 3344 Paleoclimatology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting