Analyzing ENSO teleconnections in CMIP models as a measure of model fidelity in simulating precipitation

Baird Langenbrunner and J. David Neelin J. Climate, 26, 4431-4446, doi:10.1175/JCLI-D-12-00542.1.

Paper (PDF 3.3 KB).


Abstract The accurate representation of precipitation is a recurring issue in climate models. El Niņo-Southern Oscillation (ENSO) precipitation teleconnections provide a testbed for comparison of modeled to observed precipitation. We assess the simulation quality for the atmospheric component of models in the Coupled Model Intercomparison Project Phase 5 (CMIP5), using the ensemble of runs driven by observed sea surface temperatures. Simulated seasonal precipitation teleconnection patterns are compared to observations during 1979-2005 and to the CMIP3 ensemble. Within regions of strong observed teleconnections (equatorial South America, the western equatorial Pacific, and a southern section of North America), there is little improvement in the CMIP5 ensemble relative to CMIP3 in amplitude and spatial correlation metrics of precipitation. Spatial patterns within each region exhibit substantial departures from observations, with spatial correlation coefficients typically less than 0.5. However, the atmospheric models do considerably better in other measures. First, the amplitude of the precipitation response (root mean square deviation over each region) is well estimated by the mean of the amplitudes from the individual models. This is in contrast with the amplitude of the multi-model ensemble mean, which is systematically smaller (by about 30-40%) in the selected teleconnection regions. Second, high intermodel agreement on teleconnection sign provides a good predictor for high model agreement with observed teleconnections. The ability of the model ensemble to yield amplitude and sign measures that agree with the observed signal for ENSO precipitation teleconnections lends supporting evidence for the use of the corresponding measures in global warming projections.

Citation Langenbrunner, B. and J. D. Neelin, 2012: Analyzing ENSO teleconnections in CMIP models as a measure of model fidelity in simulating precipitation. J. Climate, 26, 4431-4446, doi:10.1175/JCLI-D-12-00542.1. .

Acknowledgments. This work was supported in part by the NOAA Climate Program Office Modeling, Analysis, Predictions and Projections (MAPP) Program under grant NA11OAR4310099 as part of the CMIP5 Task Force and National Science Foundation grant AGS-1102838. We thank M. Munnich for insights into the behavior of rank correlation estimates of teleconnections. CMAP precipitation data and NOAA_ERSST_V3 SST data are provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their website at http://www.esrl.noaa.gov/psd/. We acknowledge the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modeling groups for producing and making available their model output. For CMIP, the U.S. Department of Energy's Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. Finally, we thank J. Meyerson for her significant help in data analysis and plotting.
NOAA_ERSST_V3 data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd/
CMAP Precipitation data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd/

© Copyright. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work.