20010122: GOES-7, GOES-10digital count

>From: Jason Allard <address@hidden>
>Organization: PSU
>Keywords: 200010240345.e9O3jC425238 McIDAS-X IMGREMAP MAG RES

Jason,

>All the help that you have given me in the past with IMGREMAP,
>RES, MAG, and everything else is really paying off... the results 
>are now rolling in and they look great.

Excellent!

>I do have another question... for some reason I seem to remember
>that I saw this somewhere, but I can't remember what command I
>used to find out.  I need to know the whether the GOES 7 images
>are a 6 or 8 bit digital count...

It depends on the band that you are using.  For GOES-7, the VIS images
were 6 bits and the IR 8 bits.

>and whether or not the GOES 8
>images are an 8 or 10 bit digital count.

The original images from GVAR (GOES-8, -9, -10, -11) are 10-bit.

>I need to know this
>for converting the vis brightness values to an albedo.

I just want to quickly add that the data you have GOES imagery
that has been broadcast in the Unidata-Wisconsin datastream has all
been converted to 8-bit.  For GOES-7 VIS the bits were shifted two
place to the right (so range goes to 255), and for GVAR the data
has been scaled (10 bits scaled down to 8 bits).

>Thanks for the help,

I hope that the above did help and not cloud the issue for you.

Tom

>From address@hidden Mon Jan 22 14:04:15 2001
>To: Jason Allard <address@hidden>
>Subject: 20010122: GOES-7, GOES-10digital count (cont.)

Jason,

Since I was't positive about the information I sent you in the last
eamil, I decided to check with folks at SSEC.  Here is the
real story:

GOES-7 VIS was 6-bit.

GOES-7 IR was either 9 or 10 bit depending on whether you were using
the imager or sounder (imager was 9 bit).

GVAR VIS is 10 bit, and imager IRs are 10 bit.  GVAR sounder IR channels
are 13 bit.

Sorry for the previous incorrect information.

Tom

>From address@hidden Tue Jan 23 02:11:10 2001
>Subject: 20010122: GOES-7, GOES-10digital count (cont.) 

Jason,

re: update
>Quite alright... does this negate the last bit of the previous e-mail:

>>I just want to quickly add that the data you have GOES imagery
>>that has been broadcast in the Unidata-Wisconsin datastream has all
>>been converted to 8-bit.  For GOES-7 VIS the bits were shifted two
>>place to the right (so range goes to 255), and for GVAR the data
>>has been scaled (10 bits scaled down to 8 bits).

No, it does negate the comment that the images broadcast in the
Unidata-Wisconsin datastream have been scaled to 8-bit.  By the way,
you can see how many byts are used to store pixel data in an image
from the IMGLIST output using the FORM=EXP keyword.  If the number
of bytes is 1 (one), then 9, 10, or 13 bit data has been scaled.  The
6-bit data from GOES-7 was simply right shifted by two places so that
the scale in BRITness would be the customary 0 - 255.

Tom