GOES Image Interpretation

In our last class we discussed the basic principles of remote sensing, the concept of viewing different portions of the electromagnetic spectrum with radiometers which measure radiance.  We discussed the reason for chosing selected wavelength bands, based on the radiative propterties of the sun/earth/atmosphere system.  Before we continue to develop the mathematical formulation of the radiative transfer which occurs, I wanted us to spend some time viewing some imagery.  In order to have a better understanding of what each channel can illustrate, we need to consider how these radiances measured on-board the satellite are displayed.

First we will go to a tutorial on the image enhancements, developed by NOAA/NESDIS.  Then we will go to a GOES Imager Tutorial, prepared as part of a COMET Satellite Meteorology Class.  

NOAA/NESDIS GOES Calibration Lookup Tables

GOES Calibration Lookup Tables [From the following location(http://orbit-net.nesdis.noaa.gov/arad/fpdt/goescal/goescal.html)]

Calibration tables convert the raw energy measurements made by a satellite scanning radiometer to temperatures (or albedo for the visible channel) and corresponding digital count values. The GOES Variable (GVAR) format permits a maximum of 10 bit (1024) count values in the four infrared channels and one visible channel. Many users (including the National Weather Service), reduce this to an 8 bit (256) count scale to speed transmission of the data. The infrared channels (2 through 5) are calibrated in orbit by viewing a blackbody of known temperature, then outer space. The visible detectors were calibrated prior to launch by viewing light intensities of known brightness, but are not calibrated in orbit, thus their output may diminish slowly with time.

Tables for the visible (VIS) and all infrared channels (CH2 - CH5) for both GOES-8 and GOES-9 are listed below. They were produced by Dr. Mike Weinreb and Joy Johnson of the Physics Branch of NESDIS. Each IR channel has 4 tables, 2 for each detector (a primary and a backup) times the 2 detectors per satellite.

GOES-8	GOES-9
Visible	Visible
CH2 IR	CH2 IR
CH3 WV	CH3 WV
CH4 IR	CH4 IR
CH5 IR	CH5 IR

GRAPHS are also available to show the square-root relationship between digital brightness counts and albdeo in the visible channel, and the bi-linear relationship between counts and brightness temperature in the infrared data.

NOAA/NESDIS Basics of Remote Sensing from Satellite: Enhancements

Sample GOES Enhancement Curves from NOAA/NESDIS (Images/Graphs/Descriptions)

CIRA GOES-8 Tutorial

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