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NOAA satellite in orbit.

l km2 in

The width of the strip over which NOAA passes is 2800km and is often known as the 'swath width'. If the picture is l km square, then the track might be divided into 2800 squares and since NOAA's shadow takes 116.60 km S-' = 0.15 s to pass over l km, the instrumentation must record and store all the information required from that l km2 in 0.15s. If the resolution was to be improved to 0.1 km, then there would be a ten-fold increase in data transmission. Hence, the time taken to process the data would be required to be 10 times faster should the data transfer rate be fixed. The increased resolution can only be achieved by allowing the satellite to move more slowly across the Earth's surface (impractical since this is set by the radius or orbit) or by reducing the field of view of the satellite. This allows global coverage once every several days instead of once a day. Thus, there always has to be a balance between resolution and picture frequency!