Accessibility navigation

The convection connection: how ocean feedbacks affect tropical mean moisture and MJO propagation

Demott, C. A., Klingaman, N., Tseng, W.-L., Burt, M. A., Gao, Y. and Randall, D. A. (2019) The convection connection: how ocean feedbacks affect tropical mean moisture and MJO propagation. Journal of Geophysical Research, 124 (22). pp. 11910-11931. ISSN 0148-0227

Text - Accepted Version
· Please see our End User Agreement before downloading.


It is advisable to refer to the publisher's version if you intend to cite from this work. See Guidance on citing.

To link to this item DOI: 10.1029/2019JD031015


The response of the Madden-Julian oscillation (MJO) to ocean feedbacks is studied with coupled and uncoupled simulations of four general circulation models (GCMs). Monthly mean SST from each coupled model is prescribed to its respective uncoupled simulation, to ensure identical SST mean state and low-frequency variability between simulation pairs. Consistent with previous studies, coupling improves each model's ability to propagation MJO convection beyond the Maritime Continent. Analysis of the MJO moist static energy budget reveals that improved MJO eastward propagation in all four coupled models arises from enhanced meridional advection of column water vapor (CWV). Despite the identical mean state SST in each coupled and uncoupled simulation pair, coupling increases mean-state CWV near the Equator, sharpening equatorial moisture gradients and enhancing meridional moisture advection and MJO propagation. CWV composites during MJO and non-MJO periods demonstrate that the MJO itself does not cause enhanced moisture gradients. Instead, analysis of low-level subgrid-scale moistening conditioned by rainfall rate (R) and SST anomaly reveals that coupling enhances low-level convective moistening for R > 5 mm/day; this enhancement is most prominent near the Equator. The low-level moistening process varies among the four models, which we interpret in terms of their ocean model configurations, cumulus parameterizations, and the sensitivity of convection to column relative humidity.

Item Type:Article
Divisions:Science > School of Mathematical, Physical and Computational Sciences > NCAS
Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
ID Code:86867
Publisher:American Geophysical Union


Downloads per month over past year

University Staff: Request a correction | Centaur Editors: Update this record

Page navigation