Balanced
and unbalanced aspects of secondary eyewall formation
Sergio Abarca
Naval Post Graduate School
1 pm in Room 2155
Abstract:
Secondary eyewall formation (SEF) is widely recognized as an important
research problem in the dynamics of mature tropical cyclones, but as of
yet there is not a consensus on the phenomenon’s fundamental physics.
Recent research suggests that, from a system scale perspective, both
balanced and unbalanced dynamics play an important role in SEF.
However, there is no complete quantification of the extent to which the
evolution of the fields during SEF deviate from those diagnosed
assuming balanced dynamics.
To address this question, we solve the Eliassen balanced
equation using the vortex structure and forcing functions (diabatic
heating rate and tangential momentum source) diagnosed from
convection-permitting models undergoing SEF. The resulting secondary
circulation and tangential wind tendency is compared with the azimuthal
averages of the three-dimensional simulations. In this presentation, we
show such comparisons and describe to what extent, and in which parts
of the storm, the evolution of azimuthally-averaged fields departs from
balanced dynamics.