Do gravity waves transport angular momentum away from tropical cyclones?

Abstract

Previous studies have suggested that gravity waves can transport a significantly large amount of angular momentum away from tropical cyclones, as much as 10% of the core angular momentum per hour. These previous studies used the shallow-water equations to model gravity waves radiating outward from rapidly rotating inner-core asymmetries. This issue is reinvestigated with a three-dimensional, nonhydrostatic, linear model of the vortex-anelastic equations. The response of balanced, axisymmetric vortices modeled after tropical cyclones to rotating asymmetric heat sources is examined to assess angular momentum transport by gravity waves radiating away from the core region of the vortices. Calculations show that gravity waves do transport angular momentum away from the vortex core; however, the amount transported is several orders of magnitude smaller than recent estimates. © 2010 American Meteorological Society.