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 Experimental Image Mapping System 

CONUS Images - NOAA-14 (available) - NOAA-15 (unavailable)

This page presents a demonstration of new mapping capabilities the Land Surface group is developing. NOAA-14 and NOAA-15 AVHRR 1B HRPT orbital datasets will be mapped over regions covering the Contintental United States (CONUS). Channels 1 - 5, and a Three Channel (1,2,4) Composite are currently being mapped.

Channels 1 and 2 have been scaled to to give a rough estimate of their albedos, or the amount of reflected sunlight (or solar radiation) over the amount of incoming solar radiation. The albedo is derived by dividing the digital count values by the largest possible digital count value for those channels. Note that channels 1 and 2 use slightly different wavelength ranges, and thus have different albedos. Channel 3 is unitless; the calibrated digital counts are shown. Channels 4 and 5 have been scaled to show temperatures. The 'sfc temp' version of channels 4 and 5 have been adjusted to emphasize the surface temperature. Note that channel 5 is more sensitive to water vapor than channel 4, and so the temperatures will differ especially in areas with a high water vapor concentration.

The Three Channel Composite is comprised of the AVHRR channels 1 and 2 in the range of 0 to 20 percent albedo and Channel 4 in the range of 0 to 30 Centigrade. The values for each channel are scaled from 0-255 and applied to the Red (channel 1), Green (channel 2) and Blue (channel 4) color guns, and a JPEG image produced. One may note the disconitnuities in the orbital swaths which make up the image. The polar orbiters are approximately 500 miles above the earth and as such it takes 3 or 4 orbits to completely cover the CONUS. In our scheme, warm, low clouds are slightly yellow, dry desert areas are light green to yellow, and cold clear land areas may appear blue. NOTE:NOAA-14 has drifted, and now passes overhead at approximately 4:30 local time. In the late afternoon there is less available light for the visible channels, and the Three Channel Composite appears darker and bluer.

This work was initiated by Leon Thomas (thomas@visidel.cau.edu), a summer intern from Clark Atlanta University. The Land Surface Project Area is very appreciative of his excellent work.

NOTE: Sector Images are typically 200kB.