Over the last decade efforts by NOAA and cooperating federal agencies have provided observations during progressively earlier stages of the hurricane life cycle. Tropical storms (TS, which are named systems possessing sustained wind speeds of 17-32 m/s) have thus been more frequently observed via a combination of in-situ airborne sensors, Global Positioning System (GPS) dropwindsondes, and airborne conventional and Doppler radar. Existing data archives maintained by NOAA, NASA and the USAF Hurricane Reconnaissance Squadron represent key sources of information for this study, and their further exploitation is offers a desirably economical approach. Persistent uncertainties concerning mechanisms of TS formation and subsequent rapid intensification represent an impediment to more accurate forecasts and warnings; more complete examination of aforementioned datasets may provide insights into TS formation, the subsequent evolution of these warm-core storms, and ultimately those processes responsible for development of higher-category hurricanes. Detailed atmospheric profiles obtained by arrays of GPS sondes will be objectively combined flight-level and volumetric radar data within 200 km of the center of developing TS events with a focus on lower tropospheric structures and near-surface storm inflow. Serial reconnaissance flights by the USAF offer desirable temporal resolution (viz. snapshots very 6-12 hours). Global reanalysis datasets will be used to describe the large-scale environment of the storms. Together these fields will reveal further details re: the influence of environmental factors such as the deep layer vertical shear of the horizontal wind and midlevel dry air upon internal storm features including the developing circular eyewall and enclosed eye region, spiral rainbands, and associated energy inputs into the atmospheric boundary layer.
The Intellectual Merit of this study rests in attaining more comprehensive descriptions of: reflectivity, kinematic and thermodynamic structures within developing tropical storms; the source of increased equivalent potential temperature near the storm core and its role in the formation process; the disposition of warm, moist low-level inflow directed toward the developing core; and the role of the mesoscale convectively generated vortex in TS development. Competing theories of TS formation (viz. so-called "top-down" or "bottom-up" mechanisms) will be critically evaluated using these previously untapped observations, and conditions differentiating tropical storms that attain hurricane status and those that do not will be explored. Derived fields will serve as a benchmark for detailed numerical simulations of tropical storms.
Broader Impacts of this work will be derived through the training of graduate students and the continued development of classes in tropical meteorology offered at the University of Hawaii, by enhancement of a existing partnerships between the University of Hawaii and NOAA's Hurricane Research Division, and ultimately through improved ability to better anticipate hurricane development and issue accurate warnings to the public.
