Publication Date:
2022-05-25
Description:
Author Posting. © American Meteorological Society, 2012. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 25 (2012): 2622–2651, doi:10.1175/JCLI-D-11-00301.1.
Description:
This study presents an overview of the El Niño–Southern Oscillation (ENSO) phenomenon and Pacific decadal variability (PDV) simulated in a multicentury preindustrial control integration of the NCAR Community Climate System Model version 4 (CCSM4) at nominal 1° latitude–longitude resolution. Several aspects of ENSO are improved in CCSM4 compared to its predecessor CCSM3, including the lengthened period (3–6 yr), the larger range of amplitude and frequency of events, and the longer duration of La Niña compared to El Niño. However, the overall magnitude of ENSO in CCSM4 is overestimated by ~30%. The simulated ENSO exhibits characteristics consistent with the delayed/recharge oscillator paradigm, including correspondence between the lengthened period and increased latitudinal width of the anomalous equatorial zonal wind stress. Global seasonal atmospheric teleconnections with accompanying impacts on precipitation and temperature are generally well simulated, although the wintertime deepening of the Aleutian low erroneously persists into spring. The vertical structure of the upper-ocean temperature response to ENSO in the north and south Pacific displays a realistic seasonal evolution, with notable asymmetries between warm and cold events. The model shows evidence of atmospheric circulation precursors over the North Pacific associated with the “seasonal footprinting mechanism,” similar to observations. Simulated PDV exhibits a significant spectral peak around 15 yr, with generally realistic spatial pattern and magnitude. However, PDV linkages between the tropics and extratropics are weaker than observed.
Description:
M. Alexander, A. Capotondi, and J. Scott’s participation
was supported by a grant from the NSF Climate
and Large-scale Dynamics Program. Y.-O. Kwon gratefully
acknowledges support from a WHOI Heyman
fellowship and a grant from the NSF Climate and Largescale
Dynamics Program. The CESM project is supported
by the National Science Foundation and the
Office of Science (BER) of the U.S. Department of Energy.
Description:
2012-10-15
Keywords:
Atmosphere-ocean interaction
;
El Nino
;
ENSO
;
La Nina
;
Pacific decadal oscillation
;
Climate models
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
application/pdf
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