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INTERPRETATION OF NOAA IMAGES
Compiled by Col Paull Senior Extension Officer, QDPI September
1994
National Oceanographic and Atmospheric Administration (NOAA)
is a government agency of the United States of America.
Density of green vegetation
The monthly images provide a composite big picture of the greenness of vegetation
as 'seen' from the NOAA 14 satellite over a 14-day period. In their current
form, the maps offer a purely relative measure of the density of healthy vegetation,
and hence the quality of feed on pastoral areas.
No account has been taken of differences in vegetation or soil
types, so the use must have a reasonable level of local knowledge to separate
seasonal differences from those due to different land types.
Vegetation health classes
The vegetation health classes shown on the maps span the entire range of climatic
types from arid to wet tropical coast, so many areas will only move through
a limited range of the chosen classes. For specific uses more detailed classes
can be used down to the limit of resolution of the data, which currently has
a range of approximately 100 values.
Hayed-off pasture will sometimes show as only slightly better
than bare areas, even if there is a good body of feed. Examination of a series
of maps will often provide enough information about the length of the growing
season to adequately determine the quantity of dry feed.
Other features
Permanent water such as the ocean, lakes and large dams, is shown in white.
Floodwater and bare areas in a watercourse are coloured red.
After water spreads over a flood plain, new growth shows up as green, which
turns to yellow in subsequent images as the pasture hays off.
Grey areas indicate missing data, usually resulting from cloud
cover interfering with the collection of measurements.
Within these limitations, the maps provide a useful and
reliable contribution towards gaining an up-to-date picture of seasonal conditions.
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