The relative importance of ocean advection and surface heat fluxes during the Madden-Julian oscillation in a coupled ocean-atmosphere model

Karlowska, E. ORCID: https://orcid.org/0000-0003-2401-0871, Matthews, A. J., Webber, B. G. M., Graham, T. and Xavier, P. (2024) The relative importance of ocean advection and surface heat fluxes during the Madden-Julian oscillation in a coupled ocean-atmosphere model. Journal of Geophysical Research: Oceans, 129 (11). e2024JC021515. ISSN 2169-9291 doi: 10.1029/2024JC021515

Abstract/Summary

Intraseasonal variability of ocean surface mixed layer temperature (MLT) in the tropics can be linked to the Madden-Julian Oscillation (MJO), the main source of intraseasonal atmospheric variability in the tropics. Here, we conduct a boreal winter mixed layer heat budget using 10-day forecast composites of a coupled ocean-atmosphere Numerical Weather Prediction model of the UK Met Office to reveal that ocean advection plays a major role in modulating intraseasonal anomalies of MLT over the tropical Indian Ocean and the Maritime Continent. Large scale (~10◦) intraseasonal anomalies of MLT (∼0.1◦C) are driven by net surface heat flux. Ocean advection dominates at smaller horizontal scales (~1◦), contributing up to 0.5◦C to the intraseasonal MLT anomaly. Prior to the development of the enhanced MJO convection in the western Indian Ocean (phases 8 and 1), ocean advection reinforces the net heat flux warming in this region. However, ocean advection opposes the net heat flux warming in the Maritime Continent prior to the development of suppressed MJO convection in this region. When the MJO convection develops over the central Indian Ocean (phase 3), ocean advection (net surface heat flux) drives the intraseasonal MLT anomalies in the western Indian Ocean (central Indian Ocean and the Maritime Continent). Our results demonstrate the importance of ocean dynamics during the initiation and growth of the MJO, and raise implications for models that do not resolve these processes.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/119896
Identification Number/DOI	10.1029/2024JC021515
Refereed	Yes
Divisions	No Reading authors. Back catalogue items Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	American Geophysical Union
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