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 NAA22350 for ; Fri, 24 Mar 2006 13:00:01 +0100 Received: by hector.cls.fr (Postfix) id 34084D9994; Fri, 24 Mar 2006 11:01:54 +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 EEF3E20ABA for ; Fri, 24 Mar 2006 11:01:53 +0000 (GMT) Message-Id: <6.1.1.1.2.20060323113004.021f0f68@pop.cls.fr> X-Sender: lsoudarin@pop.cls.fr X-Mailer: QUALCOMM Windows Eudora Version 6.1.1.1 Date: Thu, 23 Mar 2006 11:30:09 +0100 To: ids.analysis.forum@cls.fr From: Pascal Willis (au lieu de Laurent Soudarin ) Subject: estimating EOP rates for DORIS or not / IDS and IERS goals Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed X-Validation-by: laurent.soudarin@cls.fr Dear colleagues, thanks to all those who participated in the discussion. I reprocessed 1 year of DORIS data without estimating polar motion rates and I confirm the first results: EOP RMS towards JPL/GPS solution (no bias, no drift removed) go down to 0.2 - 0.8 mas, leading to a factor of 2 improvement, as expected. I also agree with Markus that if we don't estimate EOP rate, it will create problems when further computations are done, this is exactly why we estime polar motion and rate, per day, using 24 hours of data and no additional constrain at JPL. * Markus you will have to talk to the ILRS groups who decided some time ago not to estimate these parameters anymore. I don't think that Analysis Centers are ready to submit 2 solutions (1 for IDS to show best results and 1 for IDS with complete estimation) unless one can be derived directly from the other (no reprocessing) adding some type of constrains. It may be obvious, but people analysis these results have the possibility to use both polar motion and polar rate and fix the rate to an known series before analysis the polar motion results. This would allow distribution of complete SINEX results (polar motion and rate) but showing better polar motion results, if the technique (DORIS or SLR) does not have the data strength to really estimate the polar motion rate per day. Concerning the DORIS LCA solution, none of the hypothesis that I proposed seem to be correct (see complete answer from Jean-Michel Lemoine). However, I think that connecting the EOP estimation every 6 hours and forcing some smoothing (imposing condition on the rate) may add some rather tight constrains. * In my opinion, if the improvement does not come from this smoothing, the LCA group has to explain how they can get a factor of 2 improvements from their last solution. Not estimating the rate would be one way (see above), but it is not the case. Some tests could be conducted to show if the constrain used by LCA is tight or not. At least, we have something to discuss at the Venice meeting, and maybe also to better explain in the Position paper from Frank Lemoine, so that people can understand the consequences of these choices. Best regards 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.