These images, taken over northern Europe on July 20, 2002, depict a few
of the different views of Earth and its atmosphere that are produced by
the Atmospheric Infrared Sounder experiment system operating on NASA's
Aqua spacecraft.
The image in Figure 1 is from an infrared channel from the AIRS instrument
that measures the surface temperature in clear areas and cloud top
temperatures in cloudy areas. The image reveals very warm conditions in
France and a storm off the east coast of the United Kingdom.
The image in Figure 2 represents a microwave channel from the
Advanced Microwave Sounding Unit instrument that sees through most
clouds and observes surface conditions everywhere.
The image in Figure 3 is a microwave channel from the Humidity
Sounder for Brazil instrument that is very sensitive to humidity and
does not see the surface at all, but instead reveals the structure of
moisture streams in the troposphere.
The infrared and microwave data from the AIRS experiment are integrated
to retrieve a single set of temperature, moisture, and cloud values.
These three channels represent only a small portion of the 2,400-channel
multispectral experiment, whose primary objectives are to improve the
accuracy of weather forecasts and to study climate change.
The AIRS experiment system also takes pictures of the Earth at four
visible and near-infrared wavelengths that can be combined into a color
picture. This image shows a swirling low-pressure system over England,
clear skies over much of France, and frontal systems in the North
Atlantic. Because AIRS is sensitive to different wavelengths than your
eye, the colors shown are different from what you would see. For example,
plants appear very red to AIRS. There are also subtle color differences
in the clouds that relate to their altitude and thickness (compare the
white clouds over England with the slightly grey-green ones near Iceland).
These images are used in conjunction with other AIRS, AMSU-A, and HSB
measurements to get a full 3-D view of the atmosphere.
The Atmospheric Infrared Sounder is an instrument onboard NASA's Aqua
satellite under the space agency's Earth Observing System. The sounding
system is making highly accurate measurements of air temperature,
humidity, clouds and surface temperature. Data will be used to better
understand weather and climate. It will also be used by the National
Weather Service and the National Oceanic and Atmospheric Administration
to improve the accuracy of their weather and climate models.
The instrument was designed and built by Lockheed Infrared Imaging
Systems (recently acquired by British Aerospace) under contract with JPL.
The Aqua satellite mission is managed by NASA's Goddard Space Flight
Center.
