X-Sympa-To: ids.analysis.forum Received: from hector.cls.fr (osis.cls.fr [62.161.32.21]) by hermes.cls.fr (8.9.3/8.9.3) with ESMTP id NAA22334 for ; Fri, 24 Mar 2006 13:00:00 +0100 Received: by hector.cls.fr (Postfix) id 488978B4B7; Fri, 24 Mar 2006 11:01:53 +0000 (GMT) Delivered-To: ids.analysis.forum@cls.fr Received: from CLS-SOUDARIN.cls.fr (orange-102.cls.fr [62.161.32.13]) by hector.cls.fr (Postfix) with ESMTP id 054D920ABA for ; Fri, 24 Mar 2006 11:01:53 +0000 (GMT) Message-Id: <6.1.1.1.2.20060323112713.02171ec0@pop.cls.fr> X-Sender: lsoudarin@pop.cls.fr X-Mailer: QUALCOMM Windows Eudora Version 6.1.1.1 Date: Thu, 23 Mar 2006 11:27:49 +0100 To: ids.analysis.forum@cls.fr From: Pascal Willis (au lieu de Laurent Soudarin ) Subject: estimating DORIS pole motion rates? 1-week preliminary results Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed X-Validation-by: laurent.soudarin@cls.fr dear Laurent and Frank, here is a discussion that Frank could initiate at the next IDS meeting in Venice. Just to start the discussion, I recomputed the most recent week of DORIS data (Jan 1 to Jan 7, 2006) in 2 different ways: A) usual IGN/JPL: estimating daily pole motion + daily polar motion rate + daily UTC-UT1 rate B) usual LEGOS/CLS: estimating daily pole motion First, I don't see any change in the station coordinates results for both cases. To test for any improvement, I compute RMS of comparison for all stations with IGN04D02 solution (long-term solution) after a 7-parameter transformation. N(mm) E(mm) V(mm) case A 18.5 21.5 12.7 case B 18.4 21.1 13.0 However, I see some significant improvement in the polar motion itself. To test for improvement, I do daily difference of polar motion at 12:00 with JPL/GPS and compute a RMS of the 7 values without removing any bias. I use Bulletin B as a priori in my DORIS computations: XP(mas) YP(mas) sqrt((XP**2)+(YP**2)) case A 1.01 0.40 1.09 case B 0.68 0.54 0.87 it also removes the asymmetry I usually see between XP and YP and that Laurent does not see at all in his results. It could be related to the estimation of the daily polar motion rates that are not totally observable with DORIS. So, if we want to go from typically 1 mas polar motion results for DORIS to 0.5 mas that may be an easy way to go. The other possibility is also to add more smoothing to our daily results (imposing continuity or linearity at day boundary). Is any of these choices useful and desirable? I am ready to stop estimating polar motion rate for DORIS, but I would like to be 100% sure that nothing will be lost for IERS EOP, IERS CPP, future ITRF, IDS combination,... I would also like to be sure that all IDS groups will follow the same rules. Do you think I should do some additional tests on a longer time span to get a more reliable and convincing conclusion? Then it could make sense to enlarge the distribution list to the IDS Analysis Forum and ask for feed-back. What is your opinion? Thanks in advance Pascal -- Pascal Willis Jet Propulsion Laboratory, MS 238-646 Ph : 1-818-393-4748 4800 Oak Grove Drive FAX: 1-818-393-4965 Pasadena CA 91109 Em : Pascal.R.Willis@jpl.nasa.gov Click here to report this email as spam.