HR: 0800h
AN: GC21A-0129    [Abstracts]
TI: Downscaling ENSO Events in Nested Regional Climate Models
AU: * Arritt, R
EM: rwarritt@bruce.agron.iastate.edu
AF: Iowa State University, Department of Agronomy, Ames, IA 50011, United States
AU: Team, N
AB: We have examined the ability of an ensemble of nested regional climate models (RCMs) to provide regional detail from large-scale information during El Nino-Southern Oscillation events. This research is a component of the North American Regional Climate Change Assessment Program (NARCCAP), which is evaluating propagation of uncertainty when nested regional climate models (RCMs) are used to dynamically downscale climate projections from atmosphere-ocean general circulation models (AOGCMs). In the present application, RCM uncertainty is isolated by nesting the six NARCCAP RCMs within reanalyses of observations (the NCEP- DOE Reanalysis-2) for the period 1979-2004. The period contains two strong El Nino events (1982-83 and 1997- 98) and several other El Nino and La Nina episodes. Results show that the ENSO signal in precipitation is well represented for the west coast of North America in all of the RCMs. In that region the timing of both onset and withdrawal of ENSO-induced precipitation anomalies corresponded closely with observations, as did the spatial distribution of precipitation. ENSO-induced precipitation anomalies in the southern and eastern United States were depicted less accurately and varied more from model to model. Taking these results together with other recent findings which show that some AOGCMs can produce realistic representations of the El Nino-Southern Oscillation (ENSO), we propose that a coupled AOGCM-RCM system may provide useful projections of ENSO and its regional effects in future climates.
UR: http://www.narccap.ucar.edu/
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3355 Regional modeling
DE: 4522 ENSO (4922)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting