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Environment Reporting
Wildfires burning in Oregon, as viewed from NASA’s Aqua satellite on August 12, 2002,
using data from the MODIS instrument. The fire was sparked by lightning and by
August 14 had consumed over 375,000 acres in Oregon and northern California. Original
image in color, courtesy of Jacques Descloitres, MODIS Land Rapid Response Team.
results, it can look like a 15-year decrease,
whereas if someone else presents
only the 1980 and 1995 results, it
can look like a 15-year increase. In
cases like this, to show a more complete
picture, it’s often extremely useful
to present satellite-derived time
Finding Environmental Satellite Images on the Web
Claire Parkinson compiled a list of Web sites where reporters can find a wide selection of
satellite imagery relevant to environmental topics. They include the following:
www.nnvl.noaa.gov/
www.osei.noaa.gov
www.jpl.nasa.gov/earth
www.spot.com
http://visibleearth.nasa.gov
http://earthobservatory.nasa.gov/Newsroom
http://edcwww.cr.usgs.gov/earthshots/slow/tableofcontents ■
series in addition to the satellite imagery.
The time series, if available, can be
presented as an insert in the corner of
an image.
Similarly to the case of images and
the options for color scales, time series
can be made more or less informative
and understandable depending on the
choice of averaging interval. For example:
Satellite-derived time series of
northern hemisphere and southern
hemisphere monthly average sea-ice
concentrations from the late 1970’s to
the end of the 20th century provide a
great deal of information, but the only
signal that comes through well in the
monthly average plots is the well known
and totally unsurprising fact that much
more ice exists in winter than in summer.
The seasonal cycle so dominates
the picture that the long-term change
is not visible. By simplifying the plots
to show only yearly averages, however,
it becomes clear that the northern hemisphere
ice cover decreased overall,
while the southern hemisphere ice increased,
although neither uniformly.
The northern hemisphere case of
decreasing sea ice coverage has received
considerable attention because
of its possible connection with global
warming. Without the satellite record,
which provides global sea ice coverage
every few days, evidence of the changes
would be far less comprehensive or
convincing. The satellite-derived plots
give a much more complete picture of
overall changes than any individual
image could and show the reader much
better than most verbal descriptions
both the direction of the changes and
the considerable fluctuations.
Understood well and used properly,
satellite-derived imagery and plots
can add substantially to the information
relayed through articles about
environmental issues and environmental
change. ■
Claire Parkinson is a climatologist
at the NASA Goddard Space Flight
Center, using satellite data to examine
global climate and climate
change, with a focus on polar sea
ice. She is also project scientist for
the Aqua spacecraft, launched on
May 4, 2002, and author of the book
“Earth From Above: Using Color-
Coded Satellite Images to Examine
the Global Environment,” published
by University Science Books.
claire.parkinson@gsfc.nasa.gov
Nieman Reports / Winter 2002 89