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Title: MJO simulation in CMIP5 climate models: MJO skill metrics and process-oriented diagnosis

The Madden-Julian Oscillation (MJO) simulation diagnostics developed by MJO Working Group and the process-oriented MJO simulation diagnostics developed by MJO Task Force are applied to 37 Coupled Model Intercomparison Project phase 5 (CMIP5) models in order to assess model skill in representing amplitude, period, and coherent eastward propagation of the MJO, and to establish a link between MJO simulation skill and parameterized physical processes. Process-oriented diagnostics include the Relative Humidity Composite based on Precipitation (RHCP), Normalized Gross Moist Stability (NGMS), and the Greenhouse Enhancement Factor (GEF). Numerous scalar metrics are developed to quantify the results. Most CMIP5 models underestimate MJO amplitude, especially when outgoing longwave radiation (OLR) is used in the evaluation, and exhibit too fast phase speed while lacking coherence between eastward propagation of precipitation/convection and the wind field. The RHCP-metric, indicative of the sensitivity of simulated convection to low-level environmental moisture, and the NGMS-metric, indicative of the efficiency of a convective atmosphere for exporting moist static energy out of the column, show robust correlations with a large number of MJO skill metrics. The GEF-metric, indicative of the strength of the column-integrated longwave radiative heating due to cloud-radiation interaction, is also correlated with the MJO skill metrics, but showsmore » relatively lower correlations compared to the RHCP- and NGMS-metrics. Our results suggest that modifications to processes associated with moisture-convection coupling and the gross moist stability might be the most fruitful for improving simulations of the MJO. Though the GEF-metric exhibits lower correlations with the MJO skill metrics, the longwave radiation feedback is highly relevant for simulating the weak precipitation anomaly regime that may be important for the establishment of shallow convection and the transition to deep convection.« less
 [1] ; ORCiD logo [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7]
  1. Seoul National Univ. (Korea, Republic of)
  2. Univ. of Washington, Seattle, WA (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Seoul National Univ. (Korea, Republic of); King Abdulaziz Univ., Jeddah (Saudi Arabia)
  5. Colorado State Univ., Fort Collins, CO (United States)
  6. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab.
  7. Centre for Australian Weather and Climate Research, Melbourne, VIC (Australia)
Publication Date:
Report Number(s):
Journal ID: ISSN 0930-7575
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Climate Dynamics
Additional Journal Information:
Journal Volume: 49; Journal Issue: 11-12; Journal ID: ISSN 0930-7575
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
Contributing Orgs:
on behalf of WGNE MJO Task Force
Country of Publication:
United States
OSTI Identifier: