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Even though satellites were only available relatively
recently, they provide a more detailed view
of the wind field than that possible from ships and/or buoys. This information
is essential for estimating the uncertainty of the reconstructed wind fields.
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At some times in the past, observations from ships are too
sparse to use even with advanced statistical techniques. An understanding
of the modern wind field obtained from satellites helps identify these
times and locations.
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Wind fields measured from satellites can be used to test
methods and possible improvements.
Here is an example of how satellites can help us make
decisions which will improve the quality of our wind reconstructions...
This image shows the number of observations needed to obtain
a good estimate of the east-west (left panel) and north-south (right panel)
components of the monthly averaged wind field in 4 degree latitude by 4
degree longitude areas. Regions colored in white require many observations
to obtain a good estimate of the monthly average. This figure is
based on satellite data collected during January 1997 and is representative
of winter conditions in the northern hemisphere and summer conditions in
the southern hemisphere.
In regions where the wind is steady, and varies little
over the month, a good estimate of the monthly average can be obtained
from only a few observations. In regions where the wind is more variable,
more observations are needed to estimate the monthly average.
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Why are so many observations needed to estimate the monthly
average in the North Atlantic and North Pacific oceans?
Storms cause variations in the wind field. The
North Atlantic and North Pacific are particularly stormy in January, so
many observations are needed to estimate the monthly average of the wind.
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Do you think winds in the tropical region (near the equator)
are steady or variable in January?
Fairly steady. The blue and black shades on the
map show that a good estimate of the monthly average can be obtained from
only a few observations.
