Addison Alford-April 26

Integrated Ground-Based Radar, Aircraft, and In Situ Obs. of Hurricanes Hermine and Matthew

Asymmetric dynamical processes in TCs that lead to intensification or weakening have been diagnosed mostly through aircraft observations and numerical modeling. Oftentimes, aircraft-based radar measurements must be smoothed temporally and spatially, limiting the retrieval of convective and mesoscale processes. Modeling studies have shown that coherent eddies and vortex Rossby waves can lead to the intensification of the tangential wind, at least locally. In addition, sheared, outward propagating rainbands has been shown via modeling studies to be a result of excitation of vortex Rossby waves in the eyewall. Previous observations from the Shared Mobile Atmospheric Research and Teaching (SMART) radars have shown that vortex Rossby waves are likely tied to trailing, inner core spiral rainbands. These observations represented the first high-resolution, dual-Doppler retrievals of such processes and were qualitatively similar to previous modeling studies.

In 2016, two additional TCs were observed with SMART radar 2 (SR2), Hurricanes Hermine and Matthew. Integrated observations from ground-based radar, disdrometer measurements, and aircraft-based dropsondes are presented. SR2 and WSR-88D dual-Doppler measurements were available for 18-24 hours in each case. The Portable Integrated Precipitation Sensors (PIPS) were also deployed, located approximately 10 km from SR2. A Parsivel² disdrometer on each of the four PIPS collected drop size distribution (DSD) information that can be quantitatively compared to radar measurements. Finally, the NASA Global Hawk and the NOAA P-3 aircraft released multiple dropsondes into each storm, providing thermodynamic measurements in the inner core.

In this study, initial kinematic observations of asymmetric, convective features in the eyewall of Hurricane Hermine and in the inner core (i.e. radially outward of the eyewall) region of Hurricane Matthew are presented. Particular attention will be paid to differences between vortex Rossby wave structures observed by the SMART radars in Hurricane Isabel (2003) and Hurricane Isaac (2012). In addition, thermodynamic observations collected by the NOAA P-3 dropsondes performed in Hurricane Matthew will be related to the kinematic structure of the observed asymmetric convection. As these features propagate onshore, the microphysics of the rainbands will be examined briefly using the PIPS and the dual-polarimetric variables of SR2 and the corresponding WSR-88D for each case. Time will also be given to summarizing the next steps of this project as a result of the observations presented.