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PCMDI > WCRP CMIP3 Model Output > Diagnostic Subprojects Printer Friendly Version
 
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El Nino/Southern Oscillation in General Circulation Models

PI: Krishna AchutaRao
Institution: Lawrence Livermore National Laboratory / PCMDI
Additional Investigators: Curt Covey, Kenneth R. Sperber
Abstract:
The simulation of the El Nino/Southern Oscillation has been the subject of numerous intercomparison studies over the last decade. Given that it is the dominant mode of variability on time scales of 2-7 years, this is a mode of ocean/atmosphere variability that is important to represent in coupled models. The study of AchutaRao and Sperber (2002, Climate Dynamics, 19, 191-209) provided a standard methodology for analyzing the space-time variability of ENSO in the Coupled Model Intercomparison Project 2 (CMIP 2) models. While difficulties remain in the simulation of ENSO (e.g., amplitude, seasonality, and periodicity), our subsequent analysis of revised models from CMIP 2+ indicates that improvement in the simulation of ENSO has been realized through model development (AchutaRao et al. 2004, An Appraisal of Coupled Climate Models, PCMDI Technical Report, UCRL-TR-202550). These studies will serve as a benchmark for evaluating the performance of the IPCC simulations.

In the control simulations the variance of sea surface temperature (SST) in the key "NINO" regions will be analyzed, and spectral analysis will be used to determine how well the models represent the broadband timescale observed. The relationship between the NINO SST indices and the Southern Oscillation Index will be explored, and used for compositing EL Nino/La Nina events to determine how well the model represent the space-time structure of ENSO. The climate change simulations will be analyzed to ascertain if anthropogenically forced changes to ENSO occur. Time permitting, extratropical teleconnections of ENSO in the control and perturbed runs will investigated, with emphasis on the response over North America. The ensembles will used to assess the robustness of the response, though with 4 members it may be necessary to use a multi-model approach.

Data Requirements:

Table A1a: Monthly mean 2-d atmosphere or land surface data
psl, pr, tas, tauu, tauv, hfls, hfss, ts, uas, vas, rlut

Table A1c: Monthly mean 3d atmosphere data
ta, ua, va, zg

Table O1c: Monthly mean 2-d ocean or sea-ice data
tos

Table O1d: Monthly mean 3-d ocean or sea-ice data
thetao, uo, vo, wo
Publications:
  • AchutaRao, Krishna and K. R. Sperber, 2006: ENSO Simulation in Coupled Ocean-Atmosphere Models: Are the Current Models Better?. Climate Dynamics, 10.1007/s00382-006-0119-7. Abstract. Full Article. Edit.

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