Subject: Jason DORIS version 2 data (from Luca Cerri)
From: "Frank G. Lemoine" <[email-masked]>
To: <[email-masked]>
Date: Thu, 05 Jul 2007 17:26:14 +0000

------ Forwarded Message
From: "Cerri Luca" <[email-masked]>
Date: Wed, 4 Jul 2007 18:41:02 +0200
To: "Nikita Zelensky" <[email-masked]>, "Frank G. Lemoine"
<[email-masked]>, "jries" <[email-masked]>,
<[email-masked]>, "Pascal Willis" <[email-masked]>
Cc: <[email-masked]>, "Perrachon Pascal"
<[email-masked]>, "Houry Sabine"
<[email-masked]>, "Mercier Flavien" <[email-masked]>
Subject: RE : Jason DORIS version 2 data

Hi Nikita, Hi Everyone
 
The difference in Z between orbits obtained with the old and new
measurements files are due to the fact that there is more data in the new
files. 
In particular, this extra data before cycle 91 often belongs to SAA beacons
that were absent in old files , and that now are back in.
The following plot shows the percentage of extra measurements added back in
the new files. 
You will notice a good correlation between the total number of extra
measurements (blue curve) and your Z difference.

 

If you compared the orbits using the same mesurements you would not see that
difference. 
I agree with the fact  that the increase in the Z-bias relative to the
independent SLR/Xover reference is of concern.
That might mean that we should keep downweighting SAA stations for Jason
POD, even if the SAA corrective model is applied.
 
Best regards
 
Luca