Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/nhessd-3-4919-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
19 Aug 2015
Review status
This discussion paper is a preprint. It has been under review for the journal Natural Hazards and Earth System Sciences (NHESS). The manuscript was not accepted for further review after discussion.
A numerical study of the early stages of a tropical cyclogenesis in relation to the MJO
J. Guerbette1,2, M. Plu1,2, C. Barthe1, and J.-F. Mahfouf2 1Laboratoire de l'Atmosphère et des Cyclones, Unité Mixte CNRS/Météo-France/Université de La Réunion, La Réunion, France
2CNRM-GAME, Météo-France/CNRS, Toulouse, France
Abstract. The role of an active phase of the Madden–Julian Oscillation (MJO) on the evolution of a mesoscale convective systems (MCS) leading to a tropical depression is investigated in the South-West Indian Ocean during the Dynamics of the Madden–Julian Oscillation (DYNAMO) field experiment, with a numerical limited-area atmospheric model. A mesoscale vortex is followed in the low-troposphere from the initiation of the active MJO phase. It is shown that the interaction of the vortex with the Equatorial jet associated with the MJO plays an important role on the vortex development. As the vortex encounters the southern part of the low-level jet, it undergoes intensification that is explained by the barotropic conversion of kinetic energy from the low-level jet to the vortex.

Citation: Guerbette, J., Plu, M., Barthe, C., and Mahfouf, J.-F.: A numerical study of the early stages of a tropical cyclogenesis in relation to the MJO, Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhessd-3-4919-2015, 2015.
J. Guerbette et al.
J. Guerbette et al.

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Short summary
Active phases of the Madden-Julian Oscillation (MJO) are known to favour the formation of tropical cyclones in the South-West Indian Ocean. A meso-scale numerical simulation of a tropical cyclogenesis during such an event is investigated. A large-scale Equatorial jet that is associated with the active phase of the MJO is shown to play a major role on the early stage of the cyclogenesis, through a transfer of kinetic energy from the jet to the cyclone.
Active phases of the Madden-Julian Oscillation (MJO) are known to favour the formation of...
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