Subject: [IGSMAIL-3370]: GPS Tide Gauge Benchmark Monitoring Pilot Project / Call for Participation
From: Tilo Schoene <[email-masked]>
To: IGS Mail Administrator <[email-masked]>, Hans Peter Plag <[email-masked]>, [email-masked], Astrid Sudau <[email-masked]>
Date: Wed, 06 Jun 2001 17:25:04 +0200

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IGS Electronic Mail      06 Jun 08:30:38 PDT 2001      Message Number 3370
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Author: Tilo Schoene, GFZ Potsdam

Dear colleagues,

please find attached a Call for Participation for the GPS Tide Gauge
Benchmark Monitoring Pilot Project. You may download a pdf-version of
the document at http://op.gfz-potsdam.de/staff/schoene/TIGA_CfP.pdf .

Sincerely,
Tilo Schoene
Chair TIGA Pilot Project Committee

              INTERNATIONAL GPS SERVICE

               CALL FOR PARTICIPATION

    GPS Tide Gauge Benchmark Monitoring Pilot Project
                     (TIGA - PP)

* Letter from Chair on behalf of WG

Dear Colleague:

The IGS plays a significant role in promoting, establishing 
and the densification of a global reference system. More-
over, coordinates published and distributed by the IGS are 
used in numerous scientific applications, ranging from plate
tectonic studies to atmospheric sounding. In contrast, since
the beginning of the GPS era several studies have revealed 
the uncertainty in the GPS height component. Especially when
studying sea level changes, where the GPS height of the 
benchmark is used for defining an absolute sea level datum,
problems occur when correcting the time series for height 
changes of the benchmark.

Addressing the height component in routine computation and 
establishing and maintaining new geodetic ties to tide 
gauge systems will be further an important contribution to 
climate change studies. With the TIGA Pilot Project as 
described in the attached Call for Participation the IGS 
will again provide its expertise to a new field of 
scientific application.

For the first time it is not the intention of the IGS to 
provide results with a very low latency, but to have as 
much as possible stations included. The Pilot Project 
committee hopes that through this strategy new scientific 
applications will be driven.

Participation in this IGS activity is open to governmental 
agencies, educational and research institutions and other 
organizations whose financial resources allow a firm 
commitment to be made in support of TIGA. Proposals may be 
submitted at any time during the period ending on August 1, 
2001.

The enclosed document provides information on the 
participation solicited, where existing components will 
assume expanded roles and functions, and where new groups 
or components may be interested in contributing. Proposals 
may address single or multiple aspects of TIGA for which 
the proposing organization has the capability and capacity 
to support.

Organizations interested in participating in the TIGA 
activities should submit a Letter of Intent by July 1, 
2001, expressing their interest. IGS will offer full 
cooperation to groups involved in the development of 
support capabilities for TIGA. Participants in current 
activities are also strongly encouraged to respond to this 
solicitation.

Your interest and cooperation in participating in this 
international effort are welcomed and highly appreciated. 
Please feel free to contact the IGS Central Bureau or 
myself with questions or comments regarding this Call.

Sincerely Yours,
Tilo Schoene

                 Description of the Proposal

* Background

The GPS Tide Gauge Benchmark Monitoring - Pilot Project 
(TIGA-PP) is a pilot study of the International GPS Service 
(IGS) for establishing a service to analyze GPS data from 
stations at or near tide gauges (TG) on a continuous basis 
(CGPS @ TG). It was approved by the IGS Governing Board at 
its 16th meeting (March 25, 2001). The primary product of 
the service is time series of coordinates for analyzing 
vertical motions of Tide Gauges and Tide Gauge Benchmarks 
(TGBM). All products are made public to support and 
encourage other applications, e.g. sea level studies. In 
particular, the products of the service facilitate the 
distinction between absolute and relative sea level changes 
by accounting for the vertical uplift of the station, and 
are, therefore, an important contribution to climate change 
studies. The service may further contribute to the 
calibration of satellite altimeters and other oceanographic 
activities. The pilot project will operate for a period up 
to three years, from 2001 to 2004. After this period the 
IGS Governing Board will evaluate the project and decide 
whether or not this activity should become a regular IGS 
service function.

* Goals

The IGS has the experience and infrastructure as well as a 
stated interest to become involved in the activities for 
GPS continuous monitoring of tide gauge benchmarks. With 
its global distribution, the IGS network at tide gauges may 
become the frame for regional activities, too, like 
European Sea Level Service (ESEAS) or other regional 
networks.

The goals of the TIGA-PP are identified as follows:

1. Establish, maintain and expand a global CGPS @ TG network
     - Select a set of GPS-equipped tide gauges with a long 
       and reliable history practicable for both sea level 
       change studies and satellite altimeter calibrations.
     - Apply IGS network operation standards.
     - Promote the establishment of more continuously 
       operating GPS stations in particular in the southern 
       hemisphere.
     - Promote the establishment of links to other sites 
       which may contribute to vertical motion determination, 
       e.g., DORIS, SLR, VLBI, and/or absolute gravity 
       stations.
     - Develop recommendations for a minimum technical 
       standard of the whole tide gauge system to be included 
       into the Pilot Study, e.g., sensor types, the nature 
       of the leveling program, and metadata documentation.

2. Contribute to the procedures in which IGS realizes a 
   global reference frame in order to improve its utility 
   for global vertical geodesy. This may involve 
   reprocessing a significant subset of the (past and 
   present) IGS global tracking data set.

3. Compute precise station coordinates and velocities for 
   the CGPS @ TG stations using a processing stream that 
   runs months behind real-time in order to include the 
   largest possible number of stations. This effort will 
   incorporate all previously collected GPS data at each 
   CGPS @ TG station. Later on the combined solution will 
   have a maximum latency of one year.

4. Establish a secondary processing stream with much reduced 
   latency in order to support operational activities that 
   cannot tolerate large processing delays.

5. Monitor the stability of the network.

* Objectives

Since the success of TIGA-PP depends on two different 
sensors, GPS and tide gauges, the accuracy of both have to 
be evaluated. A total system error budget, including 
various TG instrumentations, will be explored and defined 
within the project period.

Currently a wide range of different tide gauge systems are 
in operation, ranging from traditional floating gauges to 
advanced acoustic and pressure systems. Often scientific 
applications can only be run by using data 'as they are 
provided'. However, it is expected that the IAG Special 
Commission 8 (CGPS @ TG) will recommend standards for the 
scientific implementation of GPS-equipped tide gauge 
systems. The TIGA-PP Committee will promote such efforts 
and will take actions to popularize such recommendations.

Although a new IGS site log file is currently under 
development, the information herein is insufficient for sea 
level related studies. The TIGA-PP Committee in cooperation 
with the appropriate bodies of the TG community will 
develop an augmented version of the site log to overcome 
certain limitations.

According to studies by, e.g., Guy Woppelmann, for certain 
tide gauges no ties exist to nearby GPS stations. The Pilot 
Project Committee will identify such stations and also take 
action to encourage and help with local ties.

GPS and other space geodetic techniques are only one tool 
for the determination of vertical motion rates. A strong 
preference is given to CGPS @ TG stations near absolute 
gravity sites, if possible equipped with superconducting 
gravity meters to account for short-term variations. If 
such points are available in the vicinity, ties will be 
encouraged.

Tide Gauge Data Centers (e.g. PSMSL, UHSLC, NTF) will be 
requested to support the establishment of a common tide 
gauge data format for stations participating in the TIGA-
PP. The data centers will further be requested to store and 
make available the additional meteorological data provided 
by participating stations.

* Organizational Aspects

The Call for Participation is released to enlist the 
participation of current IGS network stations, Analysis 
Centers, and Data Centers, as well as to solicit the 
participation of new stations and Analysis Centers. The IGS 
Central Bureau is asked to accept the increased 
responsibility resulting from the inclusion of the pilot 
service within the IGS. The Pilot Project will include 
stations that meet IGS network requirements. The timeliness 
for collecting data will be less stringent compared to 
standard IGS operations to allow remote stations to 
participate. The Pilot Project Committee, the IAG Special 
Commission 8 (CGPS @ TG) and the PSMSL are responsible for 
selecting the final set of stations.

* Project Committee

The TIGA-PP Committee is responsible for establishing and 
managing the service during the pilot period. The members 
are:

   - Trevor Baker, POL
   - Mike Bevis, University of Hawaii (Chair CGPS @ TG)
   - Claude Boucher, IGN
   - Remi Ferland, NRCan
   - Bruce Haines, JPL
   - John Manning, AUSLIG
   - Gary Mitchum, University of South Florida
   - Angelyn Moore, IGS Central Bureau (Network)
   - Ruth Neilan, IGS Central Bureau, Director (ex officio)
   - Steve Nerem, University of Colorado
   - Christoph Reigber, GFZ Potsdam, (Chairman IGS GB)
   - Wolfgang Scherer, NTF
   - Tilo Schoene, GFZ Potsdam (chair of TIGA-PP)
   - C.K. Shum, Ohio State University
   - Guy Woppelmann, University La Rochelle
   - Philip Woodworth, PSMSL

The Committee may ask other bodies or individuals to 
provide their expertise and to review proposals throughout 
the whole project.

The TIGA-PP Committee will evaluate, review and approve 
proposals solicited in terms of science applications for 
stations to be included, Analysis Centers and Data Centers 
taking appropriate actions as necessary. The descriptions 
and responsibilities of these fundamental IGS components 
are defined in the Terms of Reference 
(http://igscb.jpl.nasa.gov/organization/bylaws.html). 
Technical specifications for stations, Analysis Centers and 
Data Centers are included in the Call for Participation. 
The Committee will develop operational guidelines for 
incorporating the TGBM monitoring into the IGS. Links to 
the International Association of Geodesy (IAG), the 
International Association for the Physical Sciences of the 
Ocean (IAPSO), the Global Sea Level Observing System 
(GLOSS), the Permanent Service for Mean Seal Level (PSMSL), 
the European Sea Level Service (ESEAS), the APSG Seal Level 
Working Group, NOAA/NOS and other international and 
national agencies will be incorporated, as appropriate.

* Call for Participation

The TIGA Pilot Project Committee is seeking participation 
in the following categories:
   - TIGA Observing Stations
   - TIGA Data Centers
   - TIGA Analysis Centers
   - TIGA Associate Analysis Centers

In addition a Call is issued for a search for historical 
GPS and tide gauge data.

# TIGA Observing Stations

The Call goes to individual stations and organizations 
operating GPS-equipped tide gauge stations or GPS receivers 
near tide gauge stations. Stations not belonging to the IGS 
network are also welcome to answer this Call. However, only 
stations which maintain an open data policy for both GPS 
and TG data can participate. Observing stations which can 
provide support in the categories: satellite altimetry 
calibration, long-term sea level trend analysis, and global 
isostatic adjustment / uplift studies are asked to 
participate. Participating stations should have been in 
operation for several years for both GPS and tide gauges or 
the long-term deployment of a GPS-equipped tide gauge 
system should be under way.

GPS sites participating in the TIGA-PP will have to observe 
the same guidelines and rules as official IGS sites, except 
the rules for data upload and timeliness. At 
(http://igscb.jpl.nasa.gov/guide_igs.html) and 
(http://igscb.jpl.nasa.gov/join_igs.html) the guidelines 
can be found..

The primary goal of TIGA is to provide height coordinates 
and velocities of the vertical motion of the participating 
CGPS @ TG stations, but with much higher latency. This Call 
specifically targets on areas with uneven geographical 
distribution of GPS-equipped tide gauge systems, most 
notably due to the lack of communications or stations in 
coastal areas of Africa, Asia, China, India, Russia, 
Southeast Asia, South America and the polar regions.

Regular service of the TIGA Analysis Centers will have a 
latency of one year. GPS data are accepted at any date 
before. To address as many as possible science 
applications, storage of hourly data for the tide gauges is 
necessary. For sea level studies additional information 
about, e.g., air pressure and temperature, wind speed, 
direction or gust are desirable. Station owners are 
encouraged to provide these parameters together with the 
tide gauge data.

Local ties between the GPS antenna reference point and 
collocated instrumentation (e.g. DORIS, SLR, VLBI, gravity 
sites) should be known within an accuracy of about 1mm for 
the height component. In order to maintain the long-term 
stability, all TGMB's and additional BM's, including the 
GARP, should be re-leveled by a first order leveling on a 
routine basis. The repetition period depends on the local 
geographical/geological situation. For leveling between the 
TGBM and the TG within the frame of the TIGA-PP, 
responsibility shall be assumed by the TG 
owner/hydrographic office and efforts will be made to 
assess the accuracy of data. TG owner participate by 
providing the needed information and committing themselves 
to perform the leveling. Copies of the leveling log sheets 
and sketch maps should be send to TIGA Data Centers as 
well. A contact person should be identified in the 
Proposal.

TIGA Observing Station operators have the responsibility to 
coordinate their activities fully with the appropriate 
corresponding national tide gauge data authorities with 
regard to the provision of tide gauge information to the 
Pilot Project. A minimum requirement is the provision of 
monthly mean sea level values to the PSMSL. In addition, in 
accord with the requirements of the GLOSS Implementation 
Plan, hourly (or similar) 'delayed mode' raw tide gauge 
data must be made available, as soon as possible and free 
of charge, to one of the GLOSS centers (i.e. either the 
PSMSL itself, or to the University of Hawaii Sea Level 
Center (UHSLC) or to the Australian National Tidal Facility 
(NTF)), from where it will be provided to the TIGA-PP. In 
the case that such data cannot be made freely in this way, 
there should be explanation of the national tide gauge data 
policy and of any other factor which inhibits ready 
provision of the data. (Authorities which in addition are 
capable of providing data in 'fast mode', e.g. for the use 
of radar altimeter calibration, may send their data to the 
GLOSS Fast Data Center at UHSLC.)

# TIGA Data Centers

The Pilot Project will support other research activities 
incorporating tide gauge data. A prerequisite is the 
storage of additional metadata, e.g. repeated local ties 
between the GARP and the primary TGBM, as well as between 
all additional TGMB's. All archived data should be 
available by anonymous FTP for GPS data and (at least) as 
hardcopies for metadata.

Data Centers are solicited to fulfill three functions:

1. Store GPS data sent by different media (FTP, computer 
   tapes, CD-ROM, diskettes, etc.) with high and changing 
   latency.
2. Store Metadata (e.g. leveling data, sketch maps of the 
   TG) of any kind (e.g. computerized, handwritten, 
   microfiches, etc.)
3. Establish links to Tide Gauge Data Centers for easy 
   and convenient data access.

Repositories of tide gauge data for stations participating 
in the Pilot Project are in the sole responsibility of the 
appropriate national or international data centers, e.g. 
PSMSL, UHSLC, or NTF. TIGA Data Centers will not store or 
duplicate tide gauge data.

# TIGA Analysis Centers (TAC)

Analysis Centers will process tracking data of the CGPS @ 
TG network in order to calculate and make available station 
coordinates with special emphasis on the height component 
and rates of their vertical motions. All TAC's will include 
a common subset of IGS permanent stations for a common 
reference frame. To achieve a homogeneous spatial network, 
they will also agree upon the inclusion of non-CGPS @ TG 
stations. TAC's will follow recommendations given in the 
IERS Standards as far as possible.

Refer to 
(ftp://igscb.jpl.nasa.gov/igscb/resource/accharter.txt) for 
a general charter on establishing an AC.

Three types of TAC's are defined in this Call for 
Participation. Type I centers are preferred.

+ Type I  TAC's will re-compute a selected subset of the 
    IGS network data (including a retro-processing of IGS 
    station data for CGPS @ TG) for improved long-term 
    stability of the reference frame since the inception of 
    the IGS and process current and future data with a 
    latency of at least one year.

+ Type II  TAC's will process current and future data with a 
    latency of at least one year

+ Type III  TAC's will process data with reduced latency 
    in order to support operational activities that cannot 
    tolerate large processing delays.

A combination of the above is of course acceptable.
Moreover, TIGA AC's are encouraged to study the vertical 
accuracy of the GPS coordinates and to provide advice on 
their improvement. Studies of the tropospheric effects on 
the height determination, ocean loading and reference frame 
issues may also be worked out.

# TIGA Associate Analysis Centers (TAAC)

The TIGA-PP is seeking groups to perform independent 
routine analyses and evaluations of the vertical motion 
rates including:
  - Comparisons of results obtained by the TAC's similar to 
    those routinely performed by the IGS
  - Evaluations based on independent techniques, e.g., 
    DORIS, SLR, VLBI, and absolute gravity observations. 
    Proposals from those groups are encouraged.
  - TAAC's should explore and assess potential improvement 
    of the suite of IGS classical and other products, e.g., 
    PWV or vertical motions.
  - TAAC's should provide general contributions to improve 
    the processing strategy, and provide an independent but 
    critical review.

Refer to 
(ftp://igscb.jpl.nasa.gov/igscb/resource/accharter.txt) for 
a general charter on establishing an AAC.

# Survey for historical GPS and tide gauge data 

With TIGA-PP also CGPS @ TG stations can be (re)-processed, 
which where not available before due to latency or other 
reasons. This Call will encourage station owners to provide 
their archived GPS and tide gauge data to the TIGA Data 
Centers and Tide Gauge Data Centers. The only requirement 
is to observe the same guidelines such as TIGA Observing 
Stations. A Letter of Intent should be submitted.

* LETTER OF INTENT

Those organizations interested in submitting a proposal in 
response to this Call for Participation should send a one-
page non-binding Letter of Intent due by August 1, 2001. 
The Letter of Intent should state that you intend to submit 
a proposal. The letter should be sent to the IGS Central 
Bureau with a copy to the chair of the TIGA-PP:

Ruth Neilan, Director
IGS Central Bureau
Jet Propulsion Laboratory
M/S 238-540
4800 Oak Grove Drive
Pasadena, CA 91109 USA
Telephone Number: (818) 354-8330
Fax Number:       (818) 393-6686
Email:            [email-masked]

Tilo Schoene
GeoForschungsZentrum Potsdam (GFZ)
c/o DLR Oberpfaffenhofen
82234 Wessling
Telephone Number: +49-8153-281391
Fax Number:       +49-8153-281207
Email:            [email-masked]

The letter should include the following information:

  - Organization name and address
  - Name, address, and telephone and fax numbers of the 
    principal point of contact
  - Specific areas of support which will be addressed in 
    the proposal.

Letters of Intent must be received on or before July 1, 
2001. Material in these letters is for information purposes 
only and is not binding on the signatories. Those 
organizations responding will receive additional 
documentation and information in the future.

* GENERAL PROPOSAL INFORMATION

Proposals submitted in response to the Call for 
Participation must include specific details on the 
technical support that will be offered by the organization 
and a management plan. These two main proposal sections 
will be used for proposal evaluation and to facilitate 
comparative analysis. Proposals must be signed by an 
official authorized to certify institutional support, 
sponsorship and management of the proposed activities. 

Proposals are due on or before August 1, 2001, at the 
addresses provided above. To start with the Pilot Project 
activities and the coordination of the Project a very 
stringent schedule is set. Due to the importance of the 
project, groups may join at any time afterwards during the 
time of the Pilot Project. However, a Letter of Intent will 
be necessary for groups willing to join later.

* PROPOSAL EVALUATION AND SELECTION

The principal criteria considered in evaluating the 
proposal are their relevance to the IGS and TIGA-PP 
objectives, their intrinsic merit, and overall contribution 
to the service when compared to contributions available 
through other proposals. In addition to these criteria, 
management factors will be considered in the selection.

If the TIGA-PP decides to accept only a portion of the 
proposal, the submitting organization will be given the 
opportunity to accept or decline such partial acceptance.

Organizations responding to this Call for Participation 
will be notified by the Chairman of the Pilot Project 
committee of the outcome of the proposal selection process 
in September 2001.

* SCHEDULE OF IGS TIGA ACTIVITY

July 1, 2001     Letters of Intent due
August 1, 2001   Proposals due
August/September Evaluation/Selection
September 2001   Responses and Letters of Acceptance 
                 sent after the IAG General Assembly 
                 (Sep 3-7, 2001)

* PROPOSAL PREPARATION DETAILS

The Proposal should be structured as follows: 

- Cover Page (details below)
- Proposal Summary
- Description of Proposed Activities
- Management Proposal
- Financial Arrangements.

The Cover Page should contain the following information: 

- IGS TIGA component referred to
- parent/funding organization
- name and title of authorizing official 
- name and title of primary point of contact
- mailing address
- phone/fax/email
- cooperating organizations/institutes
- signatures (the cover page should be signed both by the 
  Authorizing Official committing the 
  organization/institution to the IGS activity and the 
  primary point of contact involved).

Please send your proposal via postal mail to the IGS 
Central Bureau at the above address. For easier 
distribution to the reviewers, an additional e-mail version 
should be made available (in ASCII or attached Word file). 
Please send the email version to [email-masked] and 
[email-masked].

Proposals should not exceed 15 pages.

-- 
Tilo Schoene
GeoForschungsZentrum Potsdam (GFZ), Division 1, Section 1.2

c/o DLR Oberpfaffenhofen,         D-82234 Wessling, Germany
mailto:[email-masked]    Tel: +49-(0)8153-28 1391
http://op.gfz-potsdam.de/         Fax: +49-(0)8153-28 1207