[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[GEMPAK #QYA-206571]: Embarassing Simple GINI format question, how to convert 8bit raster to actual data

This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.

  • Subject: [GEMPAK #QYA-206571]: Embarassing Simple GINI format question, how to convert 8bit raster to actual data
  • Date: Fri, 21 Nov 2014 13:40:46 -0700
> Hi Michael,
> 
> Thanks, I should have been more specific that I was interested in the GINI
> GOES products on noaaport.  So I opened an example GOES EAST VIS file and
> octet 47 is 0 (Nav/Cal Information not include), sigh.
> 
> Any ideas what the 'default' tables are for the GOES GINI products?

I didn't before but I do now!

All IR bands except WV use the same standard calibration outlined at 
http://www.goes.noaa.gov/WCIR4.html

     T = 418 - B   (B>176 OR B=176)                                     
     T = 330 - (B / 2)    (B<176 OR B=176)                              
 Where:                                                                 
     T is the brightness temperature (degrees K).                       
     B is the pixel value (0 to 255). 

The water vapor channel, I'm told, uses a different calibration range, but the 
goes.noaa.gov site for WV mentions the same two-range formula 
(http://www.goes.noaa.gov/WCWV1.html)

-Michael



Ticket Details
===================
Ticket ID: QYA-206571
Department: Support GEMPAK
Priority: Normal
Status: Open