Colorado State University Tropical Weather and Climate Research

Research

TC Structure

Check the publication list of the related research

How does CD influence TC intensification?

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Group Members: Eleanor Casas , Michael M. Bell

We developed a new, simplified conceptual model that relates TC boundary layer structural quantities---the maximum tangential wind, its radius, its height, its underlying vertical gradient, and its underlying drag coefficient---to the TC’s potential for further intensification. In addition, the new conceptual model is also able to be inverted and be used to retrieve values of interest, namely the drag coefficient under the maximum tangential wind.

What separates developing and nondeveloping disturbances?

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Group Members: C. Chelsea Nam , Dandan Tao , Michael M. Bell

To be, or not to be, that is the question of tropical cyclogenesis. Only about 15-20 % of African Easterly Waves develop into tropical cyclones (TCs). A WRF ensemble was created with multiple TC simulations spanning the relevant parameter space for three variables; 1) the VWS magnitude, 2) the environmental humidity, and 3) the initial vortex intensity. Unmeasurable random perturbations result in widely diverging scenarios in TC genesis in moderately sheared and dry environments. Here we hypothesize that the combination of moderate shear and dry air makes an unstable condition for a vortex to intensify or decay, which implifies that TC genesis in such environments may be intrinsically unpredictable in deterministic sense. We are currently looking at the link between the deep convection and the realignment of mid-level and low-level vortices comparing the developing and non-developing ensemble members.