HR: 08:00h
AN: PP51A-01 INVITED     [Abstracts]
TI: Large Scale Dynamics and High Frequency Forcing of El Niño/Southern Oscillation Variability
AU: * McPhaden, M J
EM: michael.j.mcphaden@noaa.gov
AF: NOAA Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle, WA 98115, United States
AU: Zhang, X
EM: xuebin.zhang@noaa.gov
AF: NOAA Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle, WA 98115, United States
AU: Zhang, X
EM: xuebin.zhang@noaa.gov
AF: University of Washington, School of Oceanography, Seattle, WA 98105, United States
AU: Hendon, H
EM: H.Hendon@bom.gov.au
AF: Bureau of Meteorology, Research Center, Melbourne, VIC , Australia
AU: Wheeler, M
EM: M.Wheeler@bom.gov.au
AF: Bureau of Meteorology, Research Center, Melbourne, VIC , Australia
AB: Year-to-year variability associated with the El Niño/Southern Oscillation (ENSO) is governed by large-scale ocean dynamics and coupled ocean-atmosphere interactions. However, the cycle between warm and cold phase ENSO conditions exhibits considerable irregularity in terms of amplitude, duration, and spatial and temporal patterns of development. One factor contributing to this irregularity is stochastic forcing in the form of weather noise, a prominent source of which is the Madden-Julian Oscillation (MJO). A simple two-predictor regression model is developed to estimate the relative influence of large-scale low frequency deterministic ocean- atmosphere dynamics and stochastic forcing on peak sea surface temperature (SST) anomalies associated with ENSO for the period 1980-2005. One predictor is equatorial warm water volume, which is an index for the role that upper ocean heat content plays in regulating ENSO variability. The other predictor characterizes stochastic forcing in the western Pacific in the form of an MJO activity index. The two-predictor model accounts for about 65% of peak Nino3.4 SST anomaly variance at 2-3 season lead times and suggests about equal influence (on average) of stochastic and deterministic processes affecting peak ENSO SST anomalies over the past 25 years. The implications of these results for ENSO prediction are discussed.
DE: 4215 Climate and interannual variability (1616, 1635, 3305, 3309, 4513)
DE: 4231 Equatorial oceanography
DE: 4522 ENSO (4922)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Joint Assembly