This work was funded by the National Oceanographic and Atmospheric Administration's Climate and Global Change Postdoctoral Fellowship Program. CB acknowledges additional support from the National Science Foundation (NSF) Center for Multiscale Modeling of Atmospheric Processes (CMMAP; Grant ATM0425247). This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by NSF Grant OCI-1053575. Thanks to Tom Ackerman, Zhiming Kuang, Dargan Frierson, Peter Blossey, Roj Marchand, and Dale Durran for feedback that was critical to this work. Special thanks to Eric Maloney and an anonymous reviewer for great feedback that helped improve an earlier draft of this manuscript and to Marat Khairoutdinov for developing, tuning, and distributing SPCAM3.0 through CMMAP.
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The tropical mean TOA radiation in SPCAM3.0 is remarkably realistic, owing to judicious tuning of unconstrained CRM microphysics parameters (M. Khairoutdinov 2012, personal communication). This time-consuming process has not been repeated for newer versions of SPCAM.
It could also be argued that time variations of GMS related to the MJO itself are more critical than mean-state conditions in regulating MJO amplitude in our simulations. A detailed analysis of MJO-related GMS fluctuations in the model would be necessary to further investigate this issue.
However, our configuration of SPCAM3.0 that uses unusually tiny cloud resolving model (CRM) arrays has not been as thoroughly validated. It would be interesting to verify that its behavior is fully representative of the model's baseline behavior using the more typical multiscale modeling configuration with large CRMs.