Tropical cyclone formation, both in terms of mesoscale evolution and large-scale influences; Tropical cyclone intensity change; Role of vertical wind shear at all stages of tropical cyclones; Lightning in tropical disturbances; Equatorial wave modes in the tropics

Because so little is known about them, hurricanes remain one of the most challenging phenomena to study in meteorology. This makes them especially suitable for MS and PhD research projects, because many discoveries remain to be made! These are a list of some of the questions we are trying to answer on hurricanes:

• How exactly do hurricanes form? We know the large-scale requirements reasonably well, but how does nature evolve from a synoptic-scale disturbance to a mesoscale tropical depression? We know surprisingly little about this. We are examining interactions of multiple mesoscale vortices that often develop in convective regions as well as the evolution of convective stability (the latter measured in part by lightning frequency from the network developed by former Professor Richard Orville of our department).
• In a related question, what distinguishes tropical cyclones that develop from those that reach only depression stage and no more? We are using aircraft reconnaissance data, lightning, and various satellite-based datasets to address this.
• What characterizes the larger-scale environment around forming tropical cyclones? This work includes studies of interactions of upper tropospheric troughs with incipient hurricanes, as well as studies of equatorial wave modes. As part of the latter, we are doing synoptic studies of waves in the deep tropics. These fascinating disturbances, previously known primarily through their esoteric mathematics and bizarre structure (by midlatitude standards!) are now known to dramatically influence the weather in the regions where many tropical cyclones form.
• What is the role of vertical wind shear in incipient and mature tropical cyclones? Vertical shear is generally viewed as a negative factor, but we have found some examples in which the presence of vertical wind shear excites intense vortices on the "downshear" side of tropical depressions and marginal tropical storms, and might actually aid tropical cyclone growth in early stages. We are examining the detailed response of hurricanes at all stages to vertical wind shear.

Past and Present Thesis Topics

Jaclyn Frank, MS (in progress) Mesoscale studies of tropical cyclone formation.

Carl Schreck, MS Synoptic studies of equatorial Rossby waves and their role in tropical cyclogenesis.

Kay Shelton, MS Thermodynamic structure of tropical cyclones from aircraft reconnaissance.

Kristen Corbosiero, PhD The structure and evolution of a hurricane in vertical wind shear.

Kelly Lombardo, MS Influence of equatorial Rossby waves on tropical cyclogenesis in the western Pacific.

Anantha Aiyyer, PhD Evolution of Equatorial and Tropical Disturbances in Nonuniform Environments

Daniel Lipper, MS Regions of Intense Convection in the Core of Tropical Cyclones

Michael Dickinson, PhD Influence of Large-Scale Inhomogeneities on Tropical Wave Growth and Subsequent Tropical Cyclogenesis

Kristen Corbosiero, MS The Effects of Vertical Wind Shear and Storm Motion on the Distribution of Lightning in Tropical Cyclones

Deborah Hanley, PhD Composite Study of Hurricane-Trough Interactions (co-advisor D. Keyser)

Anantha Aiyyer, MS Numerical Modeling of the Interactions of Tropical Cyclones and Upper Tropospheric Troughs

Gretchen Heller M.S. Lightning Variations in Landfalling Tropical Cyclones.

Mike Turk M.S. Tropical Cyclogenesis in the Eastern Pacific.

Jeff Freedman M.S. Meteorological Factors Associated with Positive Lightning Flashes (jointly with Prof. Idone).

Steve Skubis Ph.D. Potential Vorticity Evolution During Convective Outbreaks.

Steve Skubis M.S. Evolution of the Surface Wind Field of an Intensifying Tropical Cyclone.

Mike Dudek Ph.D. Simulation of Convective Complexes Using a Three-Dimensional Mesoscale Model.

Dave Vollaro M.S. External Influences on Hurricane Intensity.

Frank Robasky M.S. Large-scale Forcing and Secondary Eyewall Formation in Hurricane Allen.

Dan Peterson M.S. Atlantic Hurricane Intensification Climatology.

Ron Morales M.S. Interaction of a Landfalling Hurricane with a Front (jointly with Prof. Bosart).

Frank Alsheimer M.S. Genesis of Hurricane Danny (1985) in the Gulf of Mexico.