Martin:
Discussion with our Image Navigation and Registration lead (Dr. Jim Carr) reveals that the EUMETSAT GEOS projection is not the same as the GOES-R projection (i.e. the ABI fixed grid).
The reason has to do with the gimbaling characteristics of the two imagers. Both of the imagers are dual gimballed. In the case of the GEOS imager, the inner gimbal axis is in the N/S axis (i.e. the x-axis) and the outer gimbal axis is in the E/W axis (i.e. the y-axis). In the case of the GOES-R imager, this is reversed.
The implication is that the order of applying the x and y rotation matrices is reversed when data points are projected, and geodetic lat/lon coordinates calculated. As a result, the location of the data points on the Earth are different between GEOS and GOES-R for specific radian values associated with the same N/S and E/W scan angles.
As a result, the order in which the rotation matrices are applied must also be captured.
Feel free to contact me for additional details.
very respectfully,
randy
Re: [cf-satellite] Ang.: Making a proposal for the addition of the geos projection
To: <cf-satellite at xxxxxxxxxxxxxxxx>
Subject: Re: [cf-satellite] Ang.: Making a proposal for the addition of the geos projection
From: Martin Raspaud <martin.raspaud at xxxxxxx>
Date: Thu, 24 Nov 2011 09:08:12 +0100
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On 23/11/11 21:03, Tom Rink wrote:
> Hi Martin,
Hi Tom,
[...]
>> short x(x);
>> :standard_name = "projection_x_coordinate";
>> :add_offset = 1856
>> :scale_factor = -208.16554260253906
>> :units = "rad"
[...]
> This is a neat idea, that way different conventions for north-to-south
> (GOES)
> south-to-north (SEVIRI) could be handled, ie. if I'm understanding your
> suggestion?
Yes exactly. Putting negative scaling factors allows to reverse the
scanning direction so to say :)
Best regards,
Martin
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Received on Mon Nov 28 2011 - 16:24:07 GMT
