Subject: [IGSMAIL-3711]: IGS/Ionosphere Workshop, 17 and 18 January - Conclusions.
From: [email-masked]
To: [email-masked], [email-masked], [email-masked], [email-masked], [email-masked]
Date: Fri, 25 Jan 2002 16:42:44 +0100

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IGS Electronic Mail      25 Jan 07:43:14 PST 2002      Message Number 3711
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Author: Joachim Feltens
subject: IGS/Ionosphere Workshop, 17 and 18 January - Conclusions.

Dr. Joachim Feltens                            Darmstadt, 25 January 2002
IGS Ionosphere Working Group Chairman
EDS at ESOC-FDD
Robert-Bosch-Strasse 5
D-64293 Darmstadt
GERMANY
e-mail: [email-masked]

Subject: IGS/Ionosphere Workshop, 17 and 18 January - Conclusions.

Hallo Iono_WGlers, dear IGS colleagues,

please find attached the conclusions of the IGS/IAACs Ionosphere Workshop
17-18 January, 2002, here in Darmstadt. A collection of papers and foils
which were presented, will be prepared and circulated to the Iono_WG mem-
bers in the next weeks.

Best regards           Joachim Feltens

=========================================================================

                       IGS/IAACs Ionosphere Workshop

                                   ESOC

                  Darmstadt, Germany, January 17-18, 2002

                        * * * - Conclusions - * * *

1. The targets of this workshop were:

1.1 To bring Iono_WG members together.
1.2 Opportunity for each present Iono_WG member to give to the others an
    insight into his/hers work.
1.3 To talk about actions still needed to be undertaken before the routine
    delivery of a combined IGS ionosphere product can be started - this was
    the most essential part of the workshop.
1.4 Discussion of new research activities to be considered by the Iono_WG.
1.5 Discussion of points which are of vital interest for the Iono_WG within
    the IGS (e.g. enhancement of data availability from the IGS ground
    stations network).
1.6 Preparations for the IGS workshop in Ottawa, 8-11 April 2002.
1.7 To give possible Iono_WG products customers at ESOC the opportunity to
    present their wishes:
     - availability of Iono_WG products in real-time.
     - availability of predicted Iono_WG products (to prevent problems with
       the access of real-time products during ftp downtime).
     - Iono_WG products must be continuous in time, reliable and available;
       reliable TEC maps & reasonable RMS values.

2. Participants

2.1  J. Feltens (Iono_WG chairman), EDS at ESA/ESOC/Navigation Research
        Office, Darmstadt, Germany.
2.2  S. Schaer, Astronomical Institute, University of Berne (AIUB), Berne,
        Switzerland.
2.3  M. Hernandez-Pajares, Group of Astronomy & GEomatics, Polytechnical
        University of Catalonia (UPC), Barcelona, Spain.
2.4  R. Orus, Group of Astronomy & GEomatics, Polytechnical University of
        Catalonia (UPC), Barcelona, Spain.
2.5  N. Jakowski,Deutsches Zentrum fuer Luft- und Raumfahrt e.V. (DLR),
        Neustrelitz, Germany.
2.6  A. Moore (Deputy Director, IGS Central Bureau), JPL/Caltech, Pasadena,
        CA, U.S.A.
2.7  J. Cisak. (SCAR-WGGGI), Institute of Geodesy and Cartography,
        Jasna 2/4, Warszawa, Poland
2.8  N. Faehling, EDS at ESA/ESOC/Flight Dynamics Division/Interplanetary
        Group, Darmstadt, Germany.
2.9  J. Dow, ESA/ESOC/Navigation Research Office, Darmstadt, Germany.
2.10 N. Romero, GMV at ESA/ESOC/Navigation Research Office, Darmstadt,
        Germany.
2.11 C. Garcia-Martinez de Salinas, GMV at ESA/ESOC/Navigation Research
        Office, Darmstadt, Germany.

3. Conclusions

The following topics about the WG's activities were subject of discussion
between the present Iono_WG members:

1) Improvement of the weekly comparisons report:
 - The weekly report and daily short summary should be in ASCII format
   (uncompressed); a PDF version might be attached too - but the ASCII
   version should be maintained.
 - The weekly report and daily short summary should be reduced to the
   presentation of the essential parameters: systematic offsets & standard
   deviations & RMS values obtained from the external validations & the
   finally used weights - as derived from external validations RMS values -
   for the comparison/combination.
 - The weekly report and daily short summary should provide information
   about the points of best and of worst RMS-level and the RMS-values for
   different areas with GPS data (Europe, North America, Australia).
   => Action: J. Feltens (getting detailed input from the others, e.g.
   S. Schaer).

2) Further Iono_WG products validation and test methods (ionosondes,
   Envisat, IRI, ... others?):
 - Enivsat (once launched) altimeter data might be used for validations on
   routine basis in the same way as TOPEX; the ESA data policy concerning
   the availability of Envisat data has to be confirmed. => Action:
   J. Feltens.
 - Jason data might be used for validations on routine basis in the same
   way as TOPEX; the Genesis data center policy concerning the availability
   of Jason data has to be cleared up. => Action: A. Moore.
 - The test runs with an external Iono model (e.g. IRI) are important and
   not much effort and would be an easy way to verify how good the different
   IAACs ionosphere models are able to recover such an external Iono model
   => Action: all IAACs to indicate when they could perform this test.
 - ionosondes. => see under point 7).

3) Start with the routine delivery of a combined IGS ionosphere product:
 - The routine validations with TOPEX since July 2001 show an agreement of
   the "combined" IGS TEC maps with the TOPEX data on the same order as the
   best IAACs TEC maps. In the tradition of IGS products, the combined IGS
   ionosphere products will provide reliability and stability over the
   individual IAACs TEC maps & DCB values.
 - The RMS computation of the "combined" TEC has still to be improved
   slightly. => Action: J. Feltens & S. Schaer.
 - S. Schaer proposes to keep the weights computation with the external
   validation methods of UPC and EMR, but prefers to compute these weights
   globally, since the relative ratios of the weights between the IAACs
   are very similar for all latitudes, and "chessboard"-like structures,
   especially in the RMS maps of the combined TEC, could be avoided in this
   way. => must be agreed upon by all IAACs => see table below.
 - The combined IGS TEC maps should be produced with an overlap of one TEC
   map before the current day and one TEC map after the current day to
   avoid jumps in interpolated TEC when transiting from the IONEX file of
   one day to the next. => Action: J. Feltens, all IAACs as far as
   necessary.
 - The time resolution in the IONEX files might be reduced from 2 hours to
   1 hour. For a test, COD, JPL and UPC should provide 1 hours TEC maps,
   and corresponding comparisons and TOPEX validations shall be run with
   these 1 hour maps. If the comparisons and TOPEX validations indicate
   significant improvements, the time resolution should be set down to 1
   hour. - EMR and ESA are advised to enhance their time resolution!
   => Action: all IAACs & J. Feltens for corresponding comparison upgrades
   and test runs.
 - Global IAAC TEC maps should cover all parts of the world.
 - The UPC and EMR validation values should be rescaled to an equivalent
   level, before being used for combination weights computation.
   => Action: J. Feltens.
 - The interpolation scheme currently used to interpolate IAAC TEC values
   in the TOPEX validations is referred to the geographic reference frame
   and shall be replaced by an interpolation in the geomagnetic reference
   frame. => Action: J. Feltens and S. Schaer.
 - In the IONEX files the geographic latitude should be replaced by the
   geocentric latitude as reference. => must be agreed upon by all IAACs =>
   see table below.
** These proposals shall be brought to the knowledge of - and discussed
   with those IAACs, which were not present at Darmstadt (JPL and EMR) at
   the IGS Workshop in Ottawa (8-11 April 2002) and then finally be
   confirmed. If agreement is achieved, the Iono_WG shall start with the
   routine delivery of an official IGS Ionosphere Product. To realize this,
   the IAACs must support:
    + the routine delivery of Iono products,
    + the usage of global or regional weights (CODE supports global ones,
      the other IAACs must agree => see table below),
    + when the new IGS Iono product is announced, a simple measure of the
      quality should be available,
    + stations DCB values should be included.

4) Reduction of products delivery time lines, near real time & real time
   service:
 - The current combination with a 11-days delay should be maintained as
   "final" product, a new "rapid" product could be introduced.
 - Short-term processing could principally be done, and a pilot project
   should be initiated soon. The most critical point is the availability
   of a sufficient number of ground stations for short-term GPS observa-
   tion data delivery => see 10). => Action: all IAACs which are inte-
   rested and which feel to be in a position to run short-term processing
   in a pilot project.

Questionnaire for each IAAC for 3) + 4): Each IAAC shall fill up its column
in the below table either with
y ... yes, n ... no, asap ... as soon as possible, ? ... to be tried out,
glo. ... global, reg. ... regional.

IAAC                         |  COD   |  EMR   |  ESA   |  JPL   |  UPC
=============================|========|========|========|========|========
rapid                        |   y    |        |   y    |        |
ultra-rapid                  |  asap  |        |   ?    |        |
predictions                  |   y    |        |  asap  |        |
real-time                    |   n    |        |  asap  |        |
geocentric latitude in IONEX |   y    |        |   y    |        |   y
global or regional weights   |  glo.  |        |   ?    |  reg.  |

5) Identification of possible new working areas & products (occultation,
   scintillation, ... others?):
 - The WG should at the current time focus on global products.
 - Several IAACs use (or intend to use) such non-TEC data as complements to
   their GPS-derived TEC observations data.

6) Possibilities of cooperation with the SCAR/WG-GGI project:
 - Cooperation might be possible by running high-rate campaigns in the
   Antarctica (similar to HIRAC/SolarMax in April 2001) and also in the
   evaluation of old data for ionosphere studies, i.e. to use such data as
   an archive. - Before concrete actions are decided, it must be cleared up
   with the ionosphere community (COST 271), how big the interest at the
   ionosphere people is to have such data. IGS might be the node to help,
   e.g. in providing contact addresses and giving support for interested
   users. In the polar regions very interesting ionospheric phenomena can
   be observed. => Action: N. Jakowski.

7) Extension to the usage of other than GPS data (Champ, Galileo,
   ionosonde/digisonde ... others?):
 - The pure GPS-based product should be maintained.
 - A new product including other than GPS data might be an interesting opt-
   ion; it remains the question in how far such mixed products can be com-
   bined to a common IGS ionosphere product. If realized, it must be clearly
   stated which kind of observation data will be inherent in such a combined
   product.
 - The inclusion of ionosonde data might be an interesting option, and could
   at the same way also be used for routine validations through computation
   and analysis of slab thickness values => point 2). (The inclusion of
   non-GPS data might require a principal decision by the IGS Governing Board
   on whether such an inclusion conforms to the IGS terms of reference).
8) Implementation of an Iono_WG Web page:
 - Very important thing, should be done as soon as possible and could be
   realized by an extension of the IGS CB web page for the Iono_WG.
   => Action: A. Moore & S. Schaer.

9) Extended IONEX version for 3-d models:
 - Has not the highest priority at the moment.
 - The inclusion of vertical profiles should be considered.
 - UPC proposes the possibility to provide the TEC in such format. The user
   reconstruction of the STEC from 3-D models can improve using a multishell
   ionex file.

10) Stations:
 - The available ground stations distribution and data latency should be
   improved as far as possible. => Action: A. Moore.

11) Inclusion of external ionosphere models data:
 - External Iono models (e.g. IRI) are helpful in assisting to improve
   GPS-derived Iono models.