Airborne Hurricane Research

The inner core of a tropical cyclone has a mesoscale characteristic horizontal dimension (~100 km), but rotational inertia of the vortex and forcing by the surrounding flow dictate a synoptic-scale characteristic time (~105 s). Consequently, this region of the storm is an ideal target for observation by instrumented aircraft and airborne radar. Since the pioneering scientific flights in the 1950s, airborne observations have defined present understanding of tropical-cyclone structure and dynamics. Nevertheless, challenging issues remain in the dynamics of intensity change, motion, and the convective or boundary-layer features that control damage patterns at landfall.

NOAA uses two WP-3D four-engine turboprop airplanes (N42RF and N43RF) to study hurricanes. Missions, which often last 9-10 h in cloud, heavy precipitation, and turbulence, produce detailed and accurate observations of every aspect of the hurricane's central vortex. The P-3s, commissioned in 1976 and 1977, carry a suite of meteorological instruments: sensors for flight-level temperature pressure, humidity, infrared and visible electromagnetic radiation, hydrometeor phase (ice or liquid) and size distribution, and chemical tracers; active and passive microwave sensors for surface wind; and airborne weather radar including Doppler wind finding. The two airplanes working together can generate true dual-Doppler wind analyses by flying along paths such that their radar beams intersect. The airplanes deploy dropwindsondes that carry a GPS (Global Positioning System) receiver, so that their motion can measure the wind below the airplane. The new sondes are far more accurate and can resolve more detail than the old ones. Starting with the 1997 hurricane season, NOAA's new Gulfstream IV SP jet (N49RF) has carried out dedicated dropsonde missions to improve track forecasts. Observations with these more sophisticated tools promise deeper physical understanding, greatly improved numerical models, and ultimately better forecasts.

Duration: 1954 through the present.