NASA's Multi-angle Imaging SpectroRadiometer (MISR) captured these images
and cloud-top height retrievals of Hurricane Frances on September 4, 2004,
when the eye sat just off the coast of eastern Florida, and Hurricane Ivan
on September 5th, after this cyclone had devastated Grenada and was heading
toward the central and western Caribbean. Hurricane Frances made landfall
in the early hours of September 5, and was downgraded to Tropical Storm
status as it swept inland through the Florida panhandle and continued
northward. On the heels of Frances is Hurricane Ivan, which is on record as
the strongest tropical cyclone to form at such a low latitude in the
Atlantic, and was the most powerful hurricane to have hit the Caribbean in
nearly a decade.
The ability of forecasters to predict the intensity and amount of rainfall
associated with hurricanes still requires improvement, especially on the 24
to 48 hour timescale vital for disaster planning. To improve the
operational models used to make hurricane forecasts, scientists need to
better understand the multi-scale interactions at the cloud, mesoscale and
synoptic scales that lead to hurricane intensification and dissipation, and
the various physical processes that affect hurricane intensity and rainfall
distributions. Because these uncertainties with regard to how to represent
cloud processes still exist, it is vital that the model findings be
evaluated against hurricane observations whenever possible. Two-dimensional
maps of cloud height such as those shown here offer an unprecedented
opportunity for comparing simulated cloud fields against actual hurricane
observations.
The left-hand panel in each image pair is a natural color view from MISR's
nadir camera. The right-hand panels are cloud-top height retrievals
produced by automated computer recognition of the distinctive spatial
features between images acquired at different view angles. These results
indicate that at the time that these images were acquired, clouds within
Frances and Ivan had attained altitudes of 15 kilometers and 16 kilometers
above sea level, respectively. The height fields pictured here are
uncorrected for the effects of cloud motion. Wind-corrected heights (which
have higher accuracy but sparser spatial coverage) are within about 1
kilometer of the heights shown here.
The Multi-angle Imaging SpectroRadiometer observes the daylit Earth
continuously and every 9 days views the entire globe between 82° north and
82° south latitude. These data products were generated from a portion of the
imagery acquired during Terra orbits 25081 and 25094. The panels cover an
area of 380 kilometers x 924 kilometers, and utilize data from within
blocks 65 to 87 within World Reference System-2 paths 14 and 222,
respectively.
MISR was built and is managed by NASA's Jet Propulsion Laboratory,
Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra
satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD.
JPL is a division of the California In