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Date: Thu, 05 Jul 2007 17:26:44 +0000
Subject:  Jason DORIS version 2 data (from John Ries)
From: "Frank G. Lemoine" <flemoine@puuoo.gsfc.nasa.gov>
To: <ids.analysis.forum@cls.fr>
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------ Forwarded Message
From: ries@csr.utexas.edu
Date: Wed,  4 Jul 2007 16:24:30 -0500
To: Cerri Luca <luca.cerri@cnes.fr>
Cc: Nikita Zelensky <nzelensky@sgt-inc.com>, "Frank G. Lemoine"
<flemoine@puuoo.gsfc.nasa.gov>, jean-paul.berthias@cnes.fr, Pascal Willis
<willis@ipgp.jussieu.fr>, sluthcke@puuoo.gsfc.nasa.gov, Perrachon Pascal
<Pascal.Perrachon@EXCHANGE.CST.CNES.FR>, Houry Sabine
<Sabine.Houry@cnes.fr>, Mercier Flavien <flavien.mercier@cnes.fr>
Subject: Re: RE : Jason DORIS version 2 data

Hi Everyone,

I think it can be confusing to characterize the effects on the orbit as a
Z-drift, since it suggests something secular, whereas the plots show the
main
problem is a sequence of 'jumps' during the interval between cycles 60 and
90.
The rather precipitous change around cycle 80 is particularly interesting,
since
the slowly increasing data loss does not seem to have a huge change at that
point. 

Anyway, I think we want to be careful about talking about drifts (which can
lead
to confusion with the ITRF2000-2005 change) when this is clearly a sequence
of
discontinuities. The cycles before about 63 seem quite consistent with the
cycles after 90, so the puzzle resides in the cycles between 63 and 90.

Best regards,
John

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