HR: 0800h
AN: PP51E-0641    [Abstracts]
TI: Coupled Model Simulations of Mid-Holocene ENSO With Standard and Perturbed Physics Versions of HadCM3
AU: * Brown, J
EM: josephine.brown@reading.ac.uk
AF: Centre for Global Atmospheric Modelling, Department of Meteorology, University of Reading, Reading, RG6 6BB United Kingdom
AU: Collins, M
EM: matthew.collins@metoffice.gov.uk
AF: Hadley Centre for Climate Prediction and Research, Met Office, FitzRoy Road, Exeter, EX1 3PB United Kingdom
AU: Tudhope, A
EM: Sandy.Tudhope@ed.ac.uk
AF: School of Geosciences, Edinburgh University, West Mains Road, Edinburgh, EH9 3JW United Kingdom
AB: The sensitivity of ENSO to changes in background climate is investigated in simulations of mid-Holocene, present day and future conditions with the Hadley Centre coupled ocean-atmosphere model, HadCM3. In the mid-Holocene, orbitally forced changes in insolation produced changes in seasonality which may have altered ENSO amplitude and frequency. The model simulations are compared with coral isotopic records from the western Pacific Warm Pool which appear to show a substantial reduction in ENSO amplitude in the mid-Holocene. The model simulates a modest reduction in ENSO amplitude and frequency in the mid-Holocene, with a damping of SST anomalies from late boreal summer onwards in response to enhanced easterly trade winds in the central and western Pacific. We make comparisons of simulated changes in interannual central Pacific SST variability with changes in local precipitation variability over the western Pacific. This allows us to examine the extent to which western Pacific proxies may be interpreted as recording basin-scale ENSO behavior. As the response of ENSO to climate forcing may be influenced by the representation of physical processes in the model, we carry out additional simulations of mid-Holocene, present day and future climate with versions of the model in which selected physical parameters are perturbed from their standard values. Thus we present a method whereby model predictions of future ENSO behavior may be constrained by simulations of paleo conditions.
DE: 1626 Global climate models (3337, 4928)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4522 ENSO (4922)
DE: 4922 El Nino (4522)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005