A numerical study of deep convection in tropical cyclones. (14th October 2016)

• Record Type: Journal Article
• Authors: Kilroy, Gerard; Smith, Roger K.
• Is Part Of: Quarterly journal of the Royal Meteorological Society. Volume 142:Number 701(2016)
• Page Start: 3138
• Page End: 3151
• Publication Date: 2016-10-14
• Subjects: tropical cyclones -- rotating deep convection -- vortical hot towers; Meteorology -- Periodicals; 551.5
• DOI: 10.1002/qj.2895
• Languages: English
• ISSNs: 0035-9009

Abstract

Abstract : Idealized numerical model simulations are used to investigate the generation and evolution of vertical vorticity by deep convection in a warm‐cored vortex of near‐tropical‐storm strength. Deep convective updraughts are initiated by thermal perturbations located at different radii from the vortex axis. It is found that, as the location of the thermal perturbation is moved away from the axis of rotation, the updraught that results becomes stronger, the cyclonic vorticity anomaly generated by the updraught becomes weaker, the structure of the vorticity anomaly changes markedly and the depth of the anomaly increases. For an updraught along or near the vortex axis, the vorticity anomaly has the structure of a monopole and little or no anticyclonic vorticity is generated in the core. Vorticity dipoles are generated in updraughts near or beyond the radius of maximum tangential wind speed and this structure reverses in sign with height. In all cases, the vorticity anomalies persist long after the initial updraught has decayed. Implications of the results for understanding the vorticity consolidation during tropical cyclogenesis are discussed. The effects of eddy momentum fluxes associated with a single updraught on the tangential‐mean velocity tendency are investigated and a conceptual framework for the interpretation of these eddy fluxes is given. The simulations are used to appraise long‐standing ideas suggesting that latent heat release in deep convection occurring in the high inertial stability region of a vortex core is 'more efficient' than deep convection outside the core in producing temperature rise in the updraught.