Figure 1
NASA's new CloudSat satellite captured its first tropical storm, Alberto,
as it spun over the Gulf of Mexico the morning of June 12, 2006. This
image comparison shows how CloudSat "sees" such storms differently than
conventional weather satellites. The CloudSat image (top of this page and
bottom of figure 1) is compared with images obtained at nearly the same time
from two National Oceanic and Atmospheric Administration National Weather
Service tools that are mainstays for monitoring the development and
movement of tropical cyclones: the NEXRAD storm detection radar, which
maps out precipitation patterns for that portion of the storm that comes into
its range, and the GOES-12 (Geostationary Operational Environmental
Satellite) infrared imager, which is presented here to indicate the scale of
the storm and the location where CloudSat overflies it. CloudSat sees the
storm outside the range of NEXRAD and provides significantly greater vertical
detail compared to the GOES satellite. NEXRAD, for example, can only see
out to about 402 kilometers (250 nautical miles), and so could not see the
portion of the storm that CloudSat was flying over at the time. GOES-12
only sees the very top of the clouds, and cannot provide any detail about
what is being seen beneath the cloud tops.
The CloudSat data show a storm that reaches about 16 kilometers (10 miles)
in height and extends perhaps 1,000 kilometers (621 miles) in scale. The
green line at the bottom of the CloudSat image is the radar echo of the
Earth's surface. Where this line starts to disappear (change color) under
the storm is where the rainfall is heaviest. Very heavy rainfall can be
seen over about 400 kilometers (249 miles) of the satellite track. Cirrus
clouds can also been seen out ahead of the storm (near letter A) -- this
is also evident in the GOES-12 image. A smaller thunderstorm is visible in
the CloudSat image under that cirrus cloud cover near the letter A. That
storm is completely hidden from view in the GOES infrared image.