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Ocean response and feedback to tropical cyclones in the South Pacific: processes and climatology

Swen Jullien 1 
1 ECOLA - Echanges Côte-Large
LEGOS - Laboratoire d'études en Géophysique et océanographie spatiales
Abstract : Tropical cyclone (TC)-ocean interactions are essential for cyclone formation and evolution. Surface cooling is observed in the cyclone wake and is expected to exert a negative feedback to the storm intensity. This thesis provide a quantification of the ocean response and its feedback using a coupled regional model of the southwest Pacific developed for present climate long-term simulations at mesoscale resolution which are requested to separate robust features from anecdotic effects. The results highlight the neglected role of three-dimensional dynamics in the ocean and the atmosphere and tend to contradict the extreme estimations made from simple theoretical models. Previous estimates that neglect the upwelling process and ocean warm anomaly re-emergence by winter entrainment overestimate the local heat uptake by the ocean. The intensity distribution of TCs is significantly affected by the cold wake but the feedback of SST cooling to storm intensity is of moderate amplitude, compared with theoretical models based on thermodynamic arguments. Actually, our analyses contradict the direct thermodynamic control of TC intensification by surface moisture fluxes in favor of a storm-scale dynamic control. In addition, regional oceanography has a large impact on coupling. It is stronger in the Coral Sea that has shallow mixed layer and numerous eddies but extremely weak in the warm pool that has deep mixed layer, thick barrier layer and no mesoscale activity.
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Submitted on : Friday, February 7, 2014 - 4:44:33 PM
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  • HAL Id : tel-00943495, version 1

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Swen Jullien. Ocean response and feedback to tropical cyclones in the South Pacific: processes and climatology. Ocean, Atmosphere. Université Paul Sabatier - Toulouse III, 2013. English. ⟨tel-00943495⟩

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