- Related Research Areas
While tropical storm track forecasting has improved significantly over the past two decades, improvement in intensity forecasting has been slow. Previous CAMEX, TCSP, and NAMMA field campaigns provided rich data sets to study rapid intensification (RI) of hurricanes. Many processes contribute to RI such as environmental and oceanic factors but their relative importance requires much further study. There are yet many controversies over whether hot towers and convective bursts are important in RI. NASA-funded research (involving Co-I Halverson) used satellite-based studies to survey these extreme convective events. A three-year global census of bursts revealed that 80% of tropical cyclones contain one or more bursts, that these are most frequent during the genesis and intensification phases of the storm lifecycle, and that 68% of bursts were associated with storm deepening. Another TRMM-based study showed that the probability of intensification scales linearly with hot tower height; storms with eyewall hot towers exceeding 14.5 km were associated with 71% probability of deepening. The physical processes involved in RI cover multiple scales ranging from the synoptic down to the convective and smaller scales. Investigations of these processes require use of a variety of data sets ranging from satellite observations, down to small scale aircraft in situ and remote sensing measurements. Previous studies by the investigators in this proposal dealt with multiscale observational studies of hot towers and convective bursts in Hurricane Bonnie (1998) and Tropical Storm Chantal (2001) from CAMEX-3 and CAMEX-4, respectively. These studies dealt with the detailed inner core structure of these storms from EDOP and other NASA remote sensing data sets. Ongoing studies of hot towers, convective bursts, and warm cores in hurricanes include Hurricane Emily (2005) from TCSP and Hurricane Bonnie (1998), as well as additional studies of tropical hot towers from the field campaign data sets. The proposed research will complete major case studies for: a) Hurricane Bonnie with a focus on warm core/convective burst interactions over the 4 days of data collection, and b) environmental and other factors responsible for the intense convective burst in Emily Hurricane during the ER-2 flights. The Emily case provides a very interesting paradox in that the storm underwent no intensification during the most intense hot tower ever observed by EDOP. The Bonnie case provides a unique, fine-scale series of snapshots documenting the four dimensional warm core structure and evolution. It is crucial to understand how the warm core evolves, including the sense of its growth (top-down vs. bottom-up), horizontal expansion, anomaly growth, asymmetry, the response of sea level pressure through hydrostatic adjustment, and coupling to deep convection in the eyewall. Studies will be performed on convective bursts present in other tropical cyclones studied during the NASA campaigns: Dennis (2005), Gert (2005), and Helene (2006). Our overarching goal is to discern the convective- and mesoscale processes involved in the maintenance of convective bursts, their energetics, and feedback onto the larger vortex, using all available combinations of satellite, aircraft radar, flight level in situ and dropsonde data. Additional case studies may be examined as time permits, and we anticipate that the critical evaluation of our hypotheses can be used to guide planning for future flight modules designed to intensively sample convective bursts.
Project PI: Gerald Heymsfield/NASA Goddard Space Flight Center
Code 912, Goddard Space Flight Center,Greenbelt, MD 20771
Phone: (301) 614-6369
Fax: (301) 614-5492
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