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The role of the mean state on MJO simulation in CESM2 ensemble simulation
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  • Daehyun Kang,
  • Daehyun Kim,
  • Min-Seop Ahn,
  • Richard Neale,
  • Jiwoo Lee,
  • Peter Glecker
Daehyun Kang
University of Washington
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Daehyun Kim
University of Washington

Corresponding Author:[email protected]

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Min-Seop Ahn
University of Washington
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Richard Neale
National Center for Atmospheric Research (UCAR)
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Jiwoo Lee
Lawrence Livermore National Laboratory, California, USA
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Peter Glecker
LLNL
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Abstract

This study examines the role of the mean state in the propagation of the Madden-Julian Oscillation (MJO) over the Maritime Continent (MC). We use an ensemble of simulations made with a single model - the Community Earth System Model version 2 (CESM2) – to assess the effect of the mean state that is unaffected by that of model components such as parameterization schemes. Results show that one ensemble member with an exceptionally stronger MJO propagation also exhibits a much steeper background meridional moisture gradient (MMG) over the southern MC region than the other ensemble members. The simulated mean state affects MJO via its impacts on moisture dynamics - a column water vapor budget reveals a greater advection of mean moisture by MJO wind in the southern MC is responsible for the anomalous MJO activity.
28 Dec 2020Published in Geophysical Research Letters volume 47 issue 24. 10.1029/2020GL089824