About

AOS 270 Seminars

WHEN:

Wednesday, June 6

WHO:

 Gilbert Brunet

TIME:

 1:00pm

WHERE:  

Math Science 7124
TOPIC: "The importance of Vortex Rossby wave breaking and radiation for angular momentum transport in hurricanes"

Abstract:

Despite the fact that asymmetries in hurricanes, such as spiral rainbands, polygonal eyewalls and mesovortices, have long been observed in radar imagery, many aspects of their dynamics still remain unsolved, particularly in the formation of the secondary eyewall. To fill this gap, a simple 2D barotropic model and the high-resolution PSU-NCAR non-hydrostatic mesoscale model (MM5) are used to study hurricane asymmetries. The Empirical Normal Mode (ENM) diagnostics together with the Eliassen-Palm (EP) flux calculations are used to isolate wave modes from the model datasets to investigate their impact on the changes in the structure and intensity of the simulated hurricanes. The role of internal dynamics on concentric eyewall genesis is further evaluated using the full physics MM5 simulation. The leading modes of the ST-ENM diagnostics exhibit mainly characteristics of VRWs and their contribution to the EP flux divergence induced two regions of maximum tangential wind acceleration; one inside the primary eyewall which accounts for eyewall contraction and the other outside the primary eyewall which explains the development of the secondary eyewall. We will point out the expected implication of these results in the context of numerical weather prediction at different space-time resolutions for intensifying and mature hurricanes of different strengths.