Process-oriented MJO simulation diagnostic: Moisture sensitivity of simulated convection

Daehyun Kim, Prince Xavier, Eric Maloney, Matthew Wheeler, Duane Waliser, Kenneth Sperber, Harry Hendon, Chidong Zhang, Richard Neale, Yen Ting Hwang, Haibo Liu

Research output: Contribution to journalArticle

69 Scopus citations

Abstract

Process-oriented diagnostics for Madden-Julian oscillation (MJO) simulations are being developed to facilitate improvements in the representation of the MJO in weather and climate models. These processoriented diagnostics are intended to provide insights into how parameterizations of physical processes in climate models should be improved for a better MJO simulation. This paper proposes one such processoriented diagnostic, which is designed to represent sensitivity of simulated convection to environmental moisture: composites of a relative humidity (RH) profile based on precipitation percentiles. The ability of the RH composite diagnostic to represent the diversity of MJO simulation skill is demonstrated using a group of climate model simulations participating in phases 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5). A set of scalar process metrics that captures the key physical attributes of the RH diagnostic is derived and their statistical relationship with indices that quantify the fidelity of the MJO simulation is tested. It is found that a process metric that represents the amount of lower-tropospheric humidity increase required for a transition from weak to strong rain regimes has a robust statistical relationship with MJO simulation skill. The results herein suggest that moisture sensitivity of convection is closely related to a GCM's ability to simulate the MJO.

Original languageEnglish (US)
Pages (from-to)5379-5395
Number of pages17
JournalJournal of Climate
Volume27
Issue number14
DOIs
StatePublished - Jul 2014

Keywords

  • Climate models
  • Convective clouds
  • Convective parameterization
  • Diagnostics
  • Intraseasonal variability
  • Madden-Julian oscillation

ASJC Scopus subject areas

  • Atmospheric Science

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    Kim, D., Xavier, P., Maloney, E., Wheeler, M., Waliser, D., Sperber, K., Hendon, H., Zhang, C., Neale, R., Hwang, Y. T., & Liu, H. (2014). Process-oriented MJO simulation diagnostic: Moisture sensitivity of simulated convection. Journal of Climate, 27(14), 5379-5395. https://doi.org/10.1175/JCLI-D-13-00497.1