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2. converted to brightness temperatures.With steps that are nonlinear, the scale factor offset doesn't work. If a coefficient is tweaked/corrected, then the entire variable would need to be rewritten.
Satellite data often use lookup tables to more easily and quickly convert from DN to whatever (radiance/temperature). Updates would then be made to calibration tables, rather than equations.
So I would propose something like the following CDL where variable /image/ has range from 0-255 and its attribute /lookup/ means that the table to convert to meaningful units is /table_1
/
dimensions:
lat = 100
lon = 100
num_bins = 256
int image(lat,lon)
image:long_name = "GOES Water vapor channel"
image:units = "digital number"
image:lookup = "table_1"
image:valid_range = 0, 255
float table_1(num_bins)
table_1:long_name = "Brightness temperature"
table_1:units = "Kelvin"
Thoughts? -Ken -- Ken Knapp Remote Sensing and Applications Division National Climatic Data Center 151 Patton Ave Asheville, NC 28801 828-271-4339 (voice) 828-271-4328 (fax) IBTrACS: http://www.ncdc.noaa.gov/oa/ibtracs/ ISCCP B1: http://www.ncdc.noaa.gov/oa/rsad/isccpb1/ HURSAT: http://www.ncdc.noaa.gov/oa/rsad/hursat/
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