Extended Abstract (212K)13.4
Do gravity waves transport angular momentum away from hurricanes?
Yumin Moon, RSMAS/University of Miami, Miami, FL; and D. S. Nolan
Latent heat generated from the condensation in air parcel creates a localized departure in the atmosphere in hydrostatic and geostrophic balance. In response, hydrostatic and geostrophic adjustment processes gradually establish a new equilibrium in the atmosphere by dispersing the source of imbalance to the surroundings through means such as gravity waves.
The effect of convection on tropical cyclones has been examined extensively in the past but with different approaches for the representation of convection around the storm. Many studies used balanced potential vorticity perturbations to represent convection because they were considered to be the end product of a rapid adjustment process to strong localized convective heating. However, recent studies have shown the importance of capturing this rapid adjustment process (such as strong vertical acceleration and gravity wave radiation) to accurately compute the effect of convection on a tropical cyclone.
Although it has been shown that vortex-Rossby waves are dynamically more active in tropical cyclones, gravity waves certainly do exist there and may play a role which is not yet clearly defined. This study uses a three-dimensional, nonhydrostatic, but linear model to clarify the role of these gravity waves that are generated by active and asymmetric convection in the tropical cyclone core, with emphasis on angular momentum budget of the storm. In particular, gravity waves are shown to carry very little momentum away from the inner-core of the storm, in contrast with some previous results.
Session 13, Equatorial and Gravity Waves
Thursday, 28 June 2007, 10:30 AM-12:00 PM, Ballroom South
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