Research Summaries

Back The Rotating Convective Paradigm for Intensification: Studies in Eddy Dynamics and Lagrangian Coherent Structures

Fiscal Year 2017
Division Graduate School of Engineering & Applied Science
Department Meteorology
Investigator(s) Montgomery, Michael T.
Sponsor Office of Naval Research (Navy)
Summary The new conceptual paradigm for tropical-cyclone intensification recognizes the intrinsic fluid dynamics and thermodynamics of rotating deep convection as well as its collective effects in producing system-scale convergence of absolute angular momentum and amplification of the tangential wind field (Montgomery and Smith 2014, 2016). This study aims to further understand the role of non-axisymmetric 'eddy' structures in the intensification of tropical cyclone vortices. As part of this study, the commonly-assumed down-gradient mixing assumption for these eddy structures will be evaluated using both traditional Eulerian budget techniques and new Lagrangian flow techniques.
We will analyze simulations of relatively high horizontal resolution, starting first at 1 km horizontal grid spacing, and moving next to 300 m grid spacing. This project includes an increased spectrum of energy-containing, vortical convective phenomena relative to the foundation study of Persing et al. (2013). The target resolution will improve upon the representation of the vortical convective scales (of order 1 km) and capture a greater range of phenomena presently observed by intensive observation programs. In addition to traditional Eulerian analyses, we will also use Lagrangian coherent structures (LCSs) as a coordinate system to quantify transport. The analysis methodology of Rutherford et al. (2012) will be employed to study the LCSs found in the eyes and eyewalls of intensifying tropical cyclones.
The present approach using both traditional Eulerian and Lagrangian methods will provide a more complete understanding of the role of eddy structures in the transport of vorticity and local buoyancy in the evolution of 3D hurricanes.
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