Land- and Sea-surface Temperatures
AVHRR data has been used for many years to provide estimates of sea
surface temperature (SST). The potential exists to supplement AVHRR SST
by using GOES data. This is because GOES can observe an area as
frequently as once every 15-to-30 minutes, providing a greater probability of
cloud free observations than the AVHRR, which may view that same
area only twice a day. During daylight, the GOES 10.7 and 12 um
channels can be used to correct surface radiance temperatures that
have been corrupted by low-level water vapor absorption. At night-time,
information from the 3.9 um channel can be added to that from 10.7
and 12 um to improve the SST product. At 3.9 um, moisture contamination is
less since it is a cleaner window; diffraction is less, which
effectively means higher resolution; and cloud sensitivity is less.
This night-time image example is an average of five consecutive half-hourly
images from the 3.9 um channel. Cold land areas are purple and white,
lakes and water along the coast are warmer than the land (light green and
blue) but cooler than the warmer waters in the Gulf Stream, which are red
and yellow. By averaging the images, noise is greatly reduced and the
sharp temperature gradients over the water are easier to see.
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Image Applications summary page.
