Another Mission Launched From Costa Rica

NASA's ER-2 high-altitude weather research plane and the National Oceanic and Atmospheric Administration's (NOAA) P3-Orion research aircraft flew several missions July 14, 15 and 16 into the turbulent tropical atmosphere over the eastern Pacific.

The flights were intended to investigate a breeding ground of tropical cyclones -- one of the core goals of NASA's Tropical Cloud Systems and Processes (TCSP) mission, which is being conducted throughout July from San Jose, Costa Rica.

The eastern Pacific is the most concentrated spawning ground of tropical cyclones, otherwise known as hurricanes, on the planet, averaging 10-12 a year. The NOAA's P3 aircraft flew five successive missions, each about eight hours in duration. Two were flown in coordination with the ER-2. The missions commenced July 14 because large-scale conditions in the region suggested birth of a hurricane was imminent.

Just days later, on July 18, Tropical Storm Eugene developed on the far western edge of the TCSP flight zone.

The NOAA's P3 provided data on winds in the lower and middle atmosphere, while the ER-2 supplied data on the entire vertical structure of cloud, precipitation and atmospheric temperature features. During several flights, numerous small-scale circulations were documented within the "Inter-Tropical Convergence Zone," a narrow region where northeasterly and southeasterly winds converge to form thunderstorms. When the vortices coincide with strong thunderstorms, and other large-scale oceanic and atmospheric conditions are favorable, a hurricane can be generated.

Much analysis will be needed to determine if the roots of Eugene's spin can be traced to one of the vortices measured during this intensive period. The ER-2 and NOAA's P3 will provide valuable data on precursor conditions within the broader region where Tropical Storm Eugene developed.

There are different theories on why hurricanes develop in the eastern Pacific. One theory suggests disturbances that perturb the flow in the eastern Pacific arrive in the form of tropical waves from Africa, while another theory suggests the initial source of spin is essentially "homegrown" -- rotation arising from local perturbations in the regional atmosphere.

By combining the rich datasets obtained from the ER-2 and P3 aircraft with data from the unpiloted Aerosonde aircraft -- which also has been flying surveillance missions over the eastern Pacific -- and with numerical prediction models, some answers to the crucial questions of hurricane genesis soon may be forthcoming.

FMI: www.nasa.gov/vision/earth/lookingatearth/hurricane_2005.html