- Original Caption Released with Image:
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Figure 1
The image at the top of figure 1 is from a geostationary imager. The
colors relate to the temperature of the clouds. The higher the clouds, the
lower the temperature. The highest, coldest clouds are located near the
center of the hurricane. The line from A to B represents the orbit track
of CloudSat across the hurricane on 12 July. Notice that CloudSat very
nearly flew over the center of the hurricane, but at this early stage of
the storm the eye is very small and not well developed. Unlike the imager
used by the geostationary satellite, CloudSat has a only single footprint
view directly below and along the track of the orbit. However, CloudSat
can see the vertical dimension of the clouds that the geostationary imager
is unable to see, ie CloudSat "sees inside" the clouds directly under the
orbit track. This is displayed in the bottom panel of figure 1. CloudSat
sends pulses of microwave energy through the clouds, and some of the
energy in the pulses is reflected back to the spacecraft. The time delay
between when the pulse is sent and when the reflected energy is received
back at the spacecraft is mapped into a distance of the cloud from the
surface of the Earth, and the strength of the energy received is related
to how much water or ice is contained in the cloud. The colors in the
bottom panel are an indication of the strength of the returned signal,
termed the reflectivity. The red and purple areas indicate large amounts
of cloud water or precipitation. Slightly to the left of center of the
bottom panel, there is an indication of intense precipitation. We know
this because the radar signal is attenuated near the ground (notice that
the solid line along the bottom of the panel, which is the ground,
disappears in this area of intense precipitation). It is likely that in
the area the precipitation rate exceeds 30mm/hr based on previous studies.
The scale from left to right is approximately 1300 km, and the vertical
scale from top to bottom is approximately 30km.The CloudSat data indicate
that the cloud heights may be near 20km.
- Image Credit:
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NASA/JPL/The Cooperative Institute for Research in the Atmosphere (CIRA),
Colorado State University
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