On the interactions of vorticity, divergence and deformation in a meso-α-scale vortex

Abstract

Vorticity, divergence and deformation are three differentiation properties of the air flow. In this paper, by deriving the tendency equations of squared vorticity (SV), squared divergence (SD) and squared deformation (SE), it is found that the three properties can interact with each other through the terms with opposite signs in the equations. These opposite-sign terms permit a quantitative discussion on the interactions between vorticity, divergence and deformation, and the role of these interactions on weather developments. The corresponding framework is first applied to investigate the development of an extratropical meso-α-scale cyclonic vortex in China. Through diagnosing the SV equation and the interactive terms in the vortex event, it is found that the interaction between SV and SD was the controlling factor for the evolution of the vortex. The transition of SD-SV can intensify the vortex, while the transition of SV-SD causes the vortex to die out. This is consistent with the relation between vorticity and divergence that has been obtained from the vertical vorticity equation. Apart from this, a new finding is that deformation also plays a role in influencing the vortex development. On one hand, deformation can interact with vorticity to affect the vortex directly. On the other hand, deformation interacts with divergence and influence the vortex development in an indirect way. These results provide a new insight on the vortex development which is worth further investigating in the future. D G J J D J J D G J J Land SeaPublisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.