Interaction between dynamics and thermodynamics during tropical cyclogenesis Physics Department and Geophysical Research Center, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, USA
27 Mar 2014
Received: 26 April 2013 – Published in Atmos. Chem. Phys. Discuss.: 16 July 2013 Abstract. Observational data of tropical disturbances are analyzed in order to
investigate tropical cyclogenesis. Data from 37 cases observed during three
field campaigns are used to investigate possible correlations between various
dynamic and thermodynamic variables. The results show that a strong mid-level
vortex is necessary to promote spin up of the low-level vortex in a tropical
cyclone. This paper presents a theory on the mechanism of this process. The
mid-level vortex creates a thermodynamic environment conducive to convection
with a more bottom-heavy mass flux profile that exhibits a strong positive
vertical gradient in a shallow layer near the surface. Mass continuity then
implies that the strongest horizontal mass and vorticity convergence occurs
near the surface. This results in low-level vortex intensification.
Revised: 25 January 2014 – Accepted: 17 February 2014 – Published: 27 March 2014
For two of the disturbances that were observed during several consecutive
days, evolution of the dynamics and thermodynamics is documented. One of
these disturbances, Karl, was observed in the period before it intensified
into a tropical storm; the other one, Gaston, was observed after it
unexpectedly decayed from a tropical storm to a tropical disturbance. A
hypothesis on its decay is presented.
Citation: Gjorgjievska, S. and Raymond, D. J.: Interaction between dynamics and thermodynamics during tropical cyclogenesis, Atmos. Chem. Phys., 14, 3065-3082, doi:10.5194/acp-14-3065-2014, 2014.