12B.4 Retrieved Thermodynamic Structure of Hurricane Rita (2005) from Airborne Multi-Doppler Data

Tuesday, 29 August 2017: 11:15 AM
Vevey (Swissotel Chicago)
Annette M. Foerster, Colorado State Univ., Fort Collins, CO; and M. M. Bell

High-resolution three-dimensional thermodynamic fields are highly desired observations in mesoscale weather systems, but are some of the most difficult to obtain. Direct in situ measurements of pressure and temperature above the surface are limited to the paths of aircraft, radiosondes, and dropsondes. A new indirect retrieval approach, called SAMURAI-TR, will be presented, which allows estimation of three-dimensional temperature and pressure perturbations in rapidly rotating vortices such as tropical cyclones using airborne radar observations. SAMURAI-TR advances existing thermodynamic retrieval methods by allowing for a horizontal variation in the mean thermodynamic state definition, and representing the retrieved quantities as three-dimensional functions consisting of a series of finite element cubic B-splines.

SAMURAI-TR has been applied to multi-Doppler data from the Hurricane Rainband and Intensity Change Experiment (RAINEX) field campaign to analyze the structure of the eyewall convection in Hurricane Rita (2005) on 23 September. The results of the RAINEX data analysis suggest that vertical wind shear results in a wavenumber one asymmetry in both temperature and pressure that is consistent with the theoretical response of a tilted vortex by shear. Higher-order wavenumbers are connected to unbalanced motions and convective cells within the eyewall. These new insights into the observed structure of a sheared hurricane and the impact on intensity change will be discussed.

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