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
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.