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Title: The dynamical response to vertical heating structures in the tropics
Author: Taylor, James
Awarding Body: University of Reading
Current Institution: University of Reading
Date of Award: 2014
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The vertical profile of diabatic heating associated with convection is vitally important to the largescale tropical circulation. Systematic errors in diabatic heating distributions in models are considered to be a primary cause in their errors in representing the large-scale mean circulation and tropical variability in the Tropics. Much attention has been given to the vertical heating structure of the Madden-Julian Oscillation (MJO) in recent years to understand the fundamental physics of the MJO and why many general circulation models struggle to simulate a robust MJO. In this thesis, estimates of vertical diabatic heating structures from reanalysis datasets and Tropical Rainfall Measuring Mission (TRMM) latent heating algorithms are used to understand how variations in the detailed structure of the heating influence the structure in the dynamical response in the Tropics. As pan of this study, the role of the vertical structure of the heating of the MJO to the dynamical response is investigated by integrating a primitive equations model with vertical anomalous diabatic heating structures associated with the MJO. In particular, the role of a vertical tilt in the heating, which has been identified in three reanalysis datasets. is investigated in relation to the moisture convergence and energetics. An eastward phase shift of the moisture convergence of approximately 1 day directly associated with the vertical anomalous heating structure of the MJO was found for each of the reanalysis heatings. As a consequence of this phase shift, a surplus of moisture convergence over the anomalous heating was generated in regions ahead of the MIO convection centre indicating a pre-moistening of tlle atmosphere prior to deep convection. It was demonstrated that both a leading mid to shallow congestus heating and a lagging stratiform heating relative to the main MJO convection were important in contributing to the phase shift in the moisture convergence. Both these vertical heating structures may therefore be critical to the maintenance of the MJO through the warm pool region. The response to the two the heatings from the TRMM products showed no phase shift in the moisture convergence relating to the vertical heating structure of the MJO. This was due to no observable vertical tilt in the heating structure. There is increased generation of eddy entropic potential energy and conversion of that energy into eddy kinetic energy through the MJO cycle associated with the vertical anomalous heating structure of the MIO. This was related to stronger heating in the mid-troposphere generating stronger eddy potential energy (EPE) between 600 and 400 hPa, which exceeded the rcduction in generation of EPE in the planetary boundary layer (PBL).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available