The Response of a Stochastically Forced ENSO Model to Observed Off-Equatorial Wind Stress Forcing
Article
Article Title | The Response of a Stochastically Forced ENSO Model to Observed Off-Equatorial Wind Stress Forcing |
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ERA Journal ID | 1978 |
Article Category | Article |
Authors | McGregor, Shayne (Author), Holbrook, Neil J. (Author) and Power, Scott B. (Author) |
Journal Title | Journal of Climate |
Journal Citation | 22 (10), pp. 2512-2525 |
Number of Pages | 14 |
Year | 2009 |
Publisher | American Meteorological Society |
Place of Publication | United States |
ISSN | 0894-8755 |
1520-0442 | |
Digital Object Identifier (DOI) | https://doi.org/10.1175/2008JCLI2387.1 |
Web Address (URL) | https://journals.ametsoc.org/view/journals/clim/22/10/2008jcli2387.1.xml |
Abstract | This study investigates the response of a stochastically forced coupled atmosphere-ocean model of the equatorial Pacific to off-equatorial wind stress anomaly forcing. The intermediate-complexity coupled ENSO model comprises a linear, first baroclinic mode, ocean shallow water model with a steady-state, two-pressure level (250 and 750 mb) atmospheric component that has been linearized about a state of rest on the β plane. Estimates of observed equatorial region stochastic forcing are calculated from NCEP-NCAR reanalysis surface winds for the period 1950-2006 using singular value decomposition. The stochastic forcing is applied to the model both with and without off-equatorial region wind stress anomalies (i.e., poleward of 12.5° latitude). It is found that the multiyear changes in the equatorial Pacific thermocline depth 'background state' induced by off-equatorial forcing can affect the amplitude of modeled sea surface temperature anomalies by up to 1°C. Moreover, off-equatorial wind stress anomalies increased the modeled amplitude of the two biggest El Niño events in the twentieth century (1982/83 and 1997/98) by more than 0.5°C, resulting in a more realistic modeled response. These equatorial changes driven by off-equatorial region wind stress anomalies are highly predictable to two years in advance and may be useful as a physical basis to enhance multiyear probabilistic predictions of ENSO indices. © 2009 American Meteorological Society. |
Keywords | Probability Theory; Applied Mathematics; Inorganic Compounds; Organic Compounds; Ocean Engineering; Oceanography, General; Atmospheric Properties; Strength of Building Materials; Mechanical Properties; Buildings and Towers; Air-sea interaction; Air-sea interaction; THE ATMOSPHERE; Atmospheric components; Baroclinic mode; ENSO models; Equatorial forcing; Equatorial Pacific; Equatorial regions; Equatorial winds; Multiyear changes; Ocean model; Pressure level; Probabilistic prediction; Reanalysis; Sea surface temperature anomalies; Shallow water model; Stochastic forcing; Surface winds; Thermocline depth; Twentieth century; |
ANZSRC Field of Research 2020 | 370202. Climatology |
Byline Affiliations | Macquarie University |
Australian Bureau of Meteorology | |
Institution of Origin | University of Southern Queensland |
https://research.usq.edu.au/item/q66zw/the-response-of-a-stochastically-forced-enso-model-to-observed-off-equatorial-wind-stress-forcing
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