Dear Pascal, Jim, Axel, Ron, unfortunately I was at a Workshop in Wettzell last week and in Switzerland for the weekend and the first two days of this week. Therefore I could not yet answer to the various e-mails floating around. I am glad to see quite some discussions going on and I would like to add my views as well. Actually, Daniela Thaller already prepared an e-mail last week with some clarifications concerning the question of Pascal Willis while I was away. Although some of the questions may have been answered by now, I send it here, because it might help to gain a common understanding, and I add some additional comments of mine at the end. I distribute this e-mail also to the groups that answered the CfP, so that they can give additional details where needed. ========================== Answer to Pascal's e-mail: ========================== Many thanks for your detailed comments and suggestions. I will try to answer the clarification requests concerning the summary table of the proposals. I would like to start with some general remarks: The summary tables were compiled (in a first step) according to the proposals, and, you are right, there are some proposals that might be assigned to another step than given in the proposal, e.g. USNO, GRGS, and probably AICAS. But these questions were already summarized in the attached 'clarification-file' (proposals_clarification.doc) and should be discussed within the working group. Concerning your question whether the proposals are available on the web: the link to the web-site was given in the email: http://www.iers.org/iers/about/wg/wg3/ There you will find all information concerning the IERS Working Group on Combination, including the Call for Participation for the Combination Pilot Project and all proposals summarized in one pdf-document. > In this summary table, it would be nice to see the name of a person > (person in charge, point of contact) and to know the name of the > software that they will be using. > We compiled two tables (that was probably a little bit confusing?): The first one (cpp_participants.pdf) should summarize the general information about the proposals (e.g. the participating institution/organization/service, participation in which step) and there you will find as well the name of the responsible person / the person of contact for the appropriate proposal. The second table (cpp_overview.pdf) gives a more technical overview and should describe the proposed contribution in more detail. Up to now, the name of the software that will be used was not given in all proposals (actually it was not requested in the Call for Participation), therefore it is not listed in the overview. But a report/summary file is requested for all contributions and the software package should be mentioned there. Now I come to the special topics about the proposals. > 1) step 1 > > I do not understand why AUSLIG, CNES, JCET are listed. I think (but I > may be wrong) that they are going to submit individual technique > solutions from their own analysis center and not really a new > intra-technique solution. > That's true, these institutions will submit their single-technique solutions and not an intra-technique combination. At the beginning of the CfP it was not clear, if we can get an intra-technique solution from each technique, i.e., if all technique services (or one institution instead of the service) are delivering an intra-technique combination. Therefore, it was allowed to deliver as well a single-technique solution that is not yet combined with other solutions of the same technique, but in the future, for a routine process, you are right, there should be only one combined solution for each technique and not more. Concerning CNES: they wrote in the proposal explicitly that they submit their DORIS solution directly to the CPP and, in addition, to IDS for an intra-technique combination. And they really proposed to deliver position+EOP, hopefully with the full covariance. > > Concerning the NCL proposal, will they do a combined GPS solution > (like IGS) and a combined SLR solution (like ILRS). this is my present > understanding. If it is the case, they should be stated twice in this > table in step 1 (1 for SLR and 1 for GPS). If they plan to combine > GPS+SLR at the raw data level, they should appear in step 4 (like > GRGS). If they plan to combine SLR + GPS sinex solutions, they should > appear in step 2. The current presentation in the table coule be > rather misleading. > It can be seen from the proposal that they will do an intra-technique combination for GPS (as they do every week as an IGS Global Network Associated Analysis Centre) and for SLR (as they contribute to the ILRS). But it is a good suggestion to list NCL twice, one for the GPS intra-technique combination and one for the SLR intra-technique combination. That would be more clear. In addition, NCL proposes to contribute to step 2 as well, at the beginning only with a combination of GPS+SLR (from SINEX, not on observation level) but later extended to all techniques. > > In the case of IGS (and maybe other techniques), is the > intra-technique combination only performed by 1 group or by several? > In the case of IGS one group (NRCan) is doing the combination, for the other services I think it is the same. The NCL proposals are additional intra-technique contributions for GPS and SLR and appear in the table, but how the IGS, ILRS etc. contributions are generated (which single solutions are combined), that must be described in the report/summary files of the contributed solutions. The table summarizes only the proposals received for the CfP. > > Furthermore, IDS, IGS, ILRS and IVS are not really "institute" as such > but very informal groups. Did you really received an answer from these > groups as such or directly from the groups within IGS, ILRS,... doing > this type of intra-technique combination? > We received the proposals for the services via the Analysis Coordinators on behalf of IGS, IDS, ... > > 2) step 0 > > In my opinion, you should put also in this table, at least for > information, the individual techniques solutions (GFZ/GPS, Bern/GPS, > IGN-JPL/DORIS,...) that will really follow the rules given for this > specific campaign and that can really be used for this campaign in the > other steps. These individual solutions are going to be inputs for > step 1 and step 2, and maybe for 4, so we should have an explicit > list, at least for information. > As already mentioned above, the actual summary lists only the proposals received for this pilot project, and the detailed description of the intra-technique solutions should be given in the reports that must be delivered together with the solution itself. > > 3) step 2 > > It seems to me that JCET and NCL propose to do SLR+GPS at the data > measurement (and not combining sinex results per technique). I don't > understand why they are not in step 4 as GRGS is. > For NCL see the comments some paragraphs above. Concerning JCET, it is true that the proposal for step 2 looks like a combination of SLR+GPS on observation level using the co-location at the satellites and on the ground. According to the CfP a combination on the observation level, as proposed by GRGS, belongs to step 1: "In addition to the Technique Services, also institutions that perform a combination on the observation level may answer this CfP, if they are ready to routinely submit weekly solutions, where the data of at least two of the space geodetic techniques have been combined." Whether that is reasonable could be questioned, but I think that it is not really crucial for the IERS CPP to which step these solutions belong. More important is, that groups are ready to work on combinations on the observation level. These solutions should be compared and validated similarly to other solutions. > Is USNO really doing a step 2 analysis (combining of sinex solution to > derive position, EOP and quasars)? Isn't this a sort of validation > (step 3) or a special combination type (step 4). > As already mentioned in the attached topics for clarification, the USNO proposal for step 2 is limited to EOPs and therefore it should be considered as a special product or for the validation in step 3. > > 4) step 4 > > As far as know, GRGS and USNO are providing special combined products > and really both belong in this "step 4" part of your table for > different reasons. I am not so sure about AICAS and JCET. I would need > to see their original proposals to understand if they really belong in > this part of the table or not. > GRGS and USNO are discussed above. JCET will include orbits, that was probably the reason for the proposal as a special product. And from the AICAS proposal it is not yet clear where it should belong. ==================== Additional Comments: ==================== 1) Solutions from individual techniques: I think that most of the arguments for and against the submission of individual solutions have been given already. In my opinion it is very important, that the technique services develop their expertise in combining the solutions of their ACs. Therefore, the IERS should try to make sure, that these developments take place and I think that the CfP already created quite some activities within the technique services to achieve this goal and that's really good to see happening. I don't think, on the other hand, that it is a problem, if individual solutions are submitted during a transition period. It can even be very helpful to start the IERS CPP activities. We should all have the consensus, however, that the solution we aim at is, that each technique service produces its own intra-technique solution in the best possible way. After an initial phase, where individual and combined products might coexist in the IERS CPP, I hope that we will very soon achieve this status. The progress made by the technique services looks promising to me ... 2) Tomorrow I will send out a message to all the participants of the IERS CPP to inform them about - the answers to the CfP - the questions that were raised - the meeting in Nice If you agree, I will write a "letter of acceptance" to all the contributions and just ask for some clarifications (e.g. concerning the step number; that single-solutions from individual techniques are expected to disappear eventually, etc.). We will modify the tables according to the additional information we get. Tomorrow or after tomorrow we will also send out a message to the participants to inform them about how their solutions/reports/products can be included into the IERS database on a routine basis. In addition, I will ask Wolfgang Schwegmann to install an e-mail exploder for the IERS CPP, so that the e-mail discussions reach all the interested groups. Can I consider the second proposal for the naming convention accepted by the IERS WG on Combination or are there any reservations ? I think that the proposals that were sent in so far are a very good start and I expect that more will follow -- a new proposal from china that just arrived will be added to the list by tomorrow. For each of the steps we have some participants. It is clear that it will take some time to converge towards the status we are finally looking for ... With best regards, Markus -------------------------------------------------------------------------------- Prof. Dr. Markus Rothacher Phone : ++49-89-289-23191 Forschungseinrichtung Satellitengeodaesie Fax : ++49-89-289-23178 Technische Universitaet Muenchen E-mail: markus.rothacher@bv.tum.de Arcisstrasse 21 D-80290 Muenchen / Germany