The fifth session of the GLOSS Group of Experts was held at the Jet Propulsion Laboratory (JPL) 19-21 March 1997 at the invitation of Dr.Bill Melbourne and Dr.Ruth Neilan, Director of International GPS Service for Geodynamics (IGS) Central Bureau. This meeting was the first at which I had acted as GLOSS Chairman, having been Acting Chairman for the past year since the resignation of Dr.David Pugh. The meeting thanked Dr.Pugh and Dr.Albert Tolkatchev, the retiring GLOSS/GOOS Technical Secretary at IOC, for their many years of work for GLOSS.
This report is intended to provide a brief summary of some GLOSS-related activities since the GE5 meeting from my point of view. The list is an impressive one and I hope it will serve to stimulate consideration of further GLOSS products and projects (especially its regional activities) at the sixth session in Toulouse during 12-14 May.
POST-JPL PUBLICATIONS
Minutes of the fifth session of the group have been published (IOC, 1997) as has a comprehensive report on the IGS/PSMSL Workshop on GPS at tide gauges which preceded it (Neilan et al., 1998). Ruth and the IGS Central Bureau are to be thanked for producing excellent paper and web versions of this report. A draft report by the 'GPS Technical Committee' stemming from the Workshop has been prepared by the Chairman, Dr.Mike Bevis which will be debated and enhanced at the 11 May GPS at tide gauges meeting in Toulouse.
A particularly important task for the GE-5 meeting was a review of the draft new Implementation Plan for GLOSS prepared with contributions from many sea level scientists. This was endorsed by the meeting, subject to some recommended modifications, and was subsequently presented for endorsement by the 19th Session of the IOC Assembly at UNESCO House in Paris in July. The Assembly also endorsed the Plan, with minor modifications, and the final version has since been printed and circulated by IOC. It is also available on the web.
The Implementation Plan was also presented in June 1997 to international attendees at the First GOOS Forum meeting in Paris, and was discussed during the I-GOOS-III meeting following the Forum.
ACTIONS LIST
A large number of actions were generated by the GE5 meeting which can be inspected via
http://www.pol.ac.uk/psmsl/ge6/ge5actions (DEAD LINK)
I believe this was the first time such a comprehensive list was produced at a GE meeting and it has proved to be very useful in providing stimulus to activity in between meetings. Another list will be produced during GE6.
GLOSS STATUS FROM A PSMSL VIEWPOINT (OCTOBER 1998)
For the last few years, usually coinciding with a GLOSS GE meeting, the PSMSL has provided a summary of the status of GLOSS from its viewpoint. This summary has usually been made in October so as not to bias the statistics because of the seasonal cycle of data receipts.
An 'operational' station from a PSMSL viewpoint means that recent Mean Sea Level (MSL) monthly and annual values have been received at Bidston, have been checked as far as possible, and have been included in the databank. For each of the GLOSS stations, we have used the year of the last data entered into the databank, if any, to place the station into one of four categories:
Category 1: 'Operational' stations for which the latest data is 1994 or later;
Category 2: 'Probably operational' stations for which the latest data is within the period
1984-1993;
Category 3: 'Historical' stations for which the latest data is earlier than 1984;
Category 4: For which no PSMSL data exist.
Table 1 lists the numbers of stations which fall into each category for all stations. Also shown in Table 1 are the numbers in each category reported previously with the category definitions adjusted backwards one, two, three etc. years appropriately. Note that before 1993 we used the 'GLOSS90' definition of GLOSS (306 stations total), whereas 1993 onwards we have used 'GLOSS93' (308 stations total). We don't believe that change modified the statistics to a great extent. Also note that from 1997 we have used the 'GLOSS97' definition of GLOSS (287 stations total).
Overall, the statistics for 1998 are similar to those for 1997 indicating ongoing work is required to develop the network even further.
Table 1
Number of Stations in Each Category (1989-1998)
Cat. 89 90 91 92 93 94 95 96 97 97 98
1 105 133 136 158 177 183 168 186 183 182 183
2 51 50 57 46 33 35 59 46 48 47 48
3 47 42 36 29 26 26 22 21 23 17 20
4 103 81 77 73 72 64 59 55 54 41 36
Total 306 306 306 306 308 308 308 308 308 287 287
using 'GLOSS Definition'
90 90 90 90 93 93 93 93 93 97 97
GLOSS OPERATIONAL AND NON-OPERATIONAL STATIONS SURVEY (DECEMBER 1998) In December, a detailed survey was conducted of the 287 stations of the 'GLOSS Core Network' (GCN) to determine which gauges were operational or not as of February, the deadline for receipts of questionnaire replies from national authorities as part of 'GLOSS Handbook' updating. The replies were supplemented by 'PSMSL general knowledge' in the case of non-replies.
Of the 287 sites in the GCN (defined by 'GLOSS97'), only 42 are claimed to non-operational. This set is listed in Appendix 1 below. It is clear that action must be taken by national authorities to instrument the sites in order to complete the network. If national resources are limited, the authorities should be endeavouring to install equipment through bi-lateral links or possibly by making requests for second-hand equipment through IOC (see 'ge5actions' file). Alternatively, if a site cannot feasibly be instrumented, perhaps owing to environmental conditions, then IOC should be notified so that it can be reviewed for removal from the definition of the GCN at the next revision of the network.
RECONCILIATION OF THE STATISTICS OF THE PREVIOUS TWO SECTIONS
It is clear that Appendix 1 presents a more optimistic view of GLOSS status than do the statistics compiled from the PSMSL, a situation which requires investigation. One reason is that at some 'operational' locations (e.g. Tristan da Cunha and some Antarctic sites), the gauges take the form of simple pressure transducers which provide useful information for oceanography (e.g. for the World Ocean Circulation Experiment) but which do not supply MSL data, as conventionally defined, which can subsequently be submitted to the PSMSL. This situation is understandable and tolerable if there are good environmental or technical reasons for such a choice of technology.
However, a second reason is that while an 'operational' gauge might exist and be providing data of some kind, the expertise or facilities or manpower do not exist in order to process those data routinely and deliver them to the international community. This situation is not an acceptable one, as it clearly requires some kind of investment in hardware, software or training. The job of IOC/GLOSS is to remedy such situations as far as possible.
IOC TRAINING COURSES
A number of IOC/GLOSS training courses have been held since GE5 or are in the planning stage.
A training course for eight sea level scientists from Mediterranean and Black Sea countries, and also attended by a number of local people, was held at the Proudman Oceanographic Laboratory (Bidston Observatory) during 16-27 June. This course was organised by Mr.Graham Alcock, who was responsible for the many previous successful GLOSS courses at POL during the 1980s. The main themes of the course concerned the background science, the need for related geodetic measurements, and 'hands on training sessions (HOTS)'. Invited external speakers included Drs.David Pugh and M.Tsimplis (Southampton Oceanography Centre), Dr.Albert Tolkatchev (IOC), Dr.A.Plater (Liverpool University), Dr.R.Bingley (Nottingham University) and Dr.D.Rosen (Israel Oceanographic and Limnological Research). A number of POL scientists also provided lectures and organised trips to nearby tide gauges. A presentation was made to Dr.Tolkatchev to mark his retirement.
The POL course was co-funded by the Commission Internationale pour l'Exploration Scientifique de la Mer Mediterranee (CIESM), and and was followed by a sea level summer school in Kos, Greece in July for Mediterranean scientists funded by the European Union. Mediterranean sea levels consequently received considerable attention in 1997.
A further, but larger GLOSS training course in a similar style to the Dehra Dun 1995 and POL 1997 courses was held at the University of Cape Town (UCT) during 16-27 November 1998 organised by Prof.Geoff Brundrit and Dr.Howard Waldron. This course had ten 'official' attendees from Africa, Yemen and Brazil and a large number of local participants. Invited external speakers included Drs.Philip Woodworth and Trevor Baker (POL) and Mme.Janice Trotte (IOC) with other lectures by UCT staff. The main themes of the course concerned background sea level science (climate change, oceanography), the need for related geodetic measurements, and HOTS. Visits to tide gauge and geological sea level sites were also provided as were exercises in geodetic levelling. The opportunity was taken to also discuss plans for action in east, south and west Africa as part of GLOSS and of the Global Ocean Observing System (GOOS) for Africa. This was a very successful course, for which a workshop report will shortly be available containing extensive reviews of status in each participating country.
A further training course has been proposed at the University of Sao Paulo, Brazil in September 1999 following recommendations of the GE5 meeting and of the IOC Executive Council in 1998. Proposals for training courses therafter will be discussed at the GLOSS GE6 session and will of course be subject to available funding.
TRAINING MATERIALS
The two parts of the IOC Manuals and Guides No.14 are now showing their age and their updating or replacement needs to be discussed. A 'Part 3' on 'How to Operate GPS Near a Tide Gauge' is to be produced by the 'GPS Technical Committee' with the three parts of the overall Manual published together or separately as appropriate.
Several sets of tidal analysis software continue to be widely distributed and play a major role in improving data quality and timely delivery. The most used is that of Pat Caldwell from the University of Hawaii; this formed the basis of 'HOTS' at Dehra Dun 1995 for example. The TASK-2000 package from POL was used at the POL 1997 and UCT 1998 courses. Either the Caldwell package or local USP software will be used at the USP 1999 course. A further package is available from the Australian NTF.
A number of GLOSS-related CD-ROMS have been produced over the last few years, primarily by the British Oceanographic Data Centre (BODC) and the National Oceanic and Atmospheric Administration (NOAA), containing GLOSS Handbook and PSMSL data sets and the World Ocean Circulation Experiment (WOCE) Sea Level Centre files, together with scanned versions of the IOC Manuals which can be read with Adobe Acrobat software. The most recent version is that produced for the International WOCE Conference in Halifax, Canada in May 1998. In preparation for that conference, BODC and the PSMSL circulated all GLOSS Contacts with a request to update and extend the information in the current version of the Handbook and that exercise will be repeated in 1999. Most of the files on the CD-ROMs are also available on the web. The Handbook can be inspected at:
http://www.pol.ac.uk/bodc/glosshb/glosshb4.htm
and any scientist with updated information to provide, or comments to make on particular sites, is invited to contact the PSMSL.
NEWSLETTERS AND BROCHURE
There have been 6 issues of the GLOSS Bulletin on the web. The PSMSL has undertaken to produce a 7th in 1999, primarily using contributions from GE6. Thereafter, a volunteer organisation is required to take over production of the Bulletin. The Afro-American GLOSS News (AAGN) also continues to be produced regularly. This newsletter has articles mostly in Spanish and Portuguese, and is produced by the University of Sao Paulo on paper and on the web. A special GLOSS newsletter for Africa was suggested at the UCT training course.
All sea level centres (PSMSL, BODC, UHSCL, NTF) now have good web pages which serve to spread information to the public as well as the science community.
An updated two page brochure advertising GLOSS has been produced by Gillian Spencer and Robert Smith. Two thousand copies have been printed for circulation in the UK and we hope that others will be printed by UNESCO. We also hope that GLOSS National and Regional Contacts will arrange for printing in their own countries. Copies of the files which make up the brochure (Corel Draw files) may be sent to anyone interested who can edit and adapt them according to local interests.
GLOSS EMAIL SURVEY
All GLOSS Contacts can now be reached via electronic mail except for those from the following countries. If email addresses exist which we are not familiar with, we would be very grateful for the information:
Angola, Bangladesh, Cameroon, People's Republic of China, Congo, Djibouti, El Salvador, Fiji, Guinea, Haiti, Indonesia, Jamaica, North Korea, Madagascar, Mauritania, Mexico, Morocco, Myanmar (Burma), Panama, Sao Tome & Principe, Sierra Leone, Somalia, Sri Lanka, Tanzania, Thailand, Trinidad & Tobago, Uruguay and Yemen.
RELEVANT GLOSS-RELATED MEETINGS
Full meetings of the GLOSS Group of Experts (GGE) take place at approximately two-yearly intervals. However, it is our intention that international collaboration will be enhanced by holding regional meetings in intervening years whenever possible.
An excellent GLOSS-related workshop on different aspects of sea level studies, concentrating especially on climate and oceanographic interests, took place at the University of Hawaii, Honolulu, USA during 10-11 June 1997. This workshop considered the roles of remotely sensed and in situ systems for monitoring different aspects of the ocean/climate system which result in observable sea level signals. A workshop report, edited by Dr.N.Smith (Chairman of the Ocean Observing Panel on Climate, OOPC), and a study of the global network by Dr.V.Gornitz (Goddard Institute for Space Studies), was published in 1998.
One recommendation of the meeting relates to the possibility of establishing a scientific sea level advisory group jointly between IOC/GLOSS and other bodies (such as CLIVAR and the OOPC) to provide ongoing scientific advice to the wider GLOSS group. This will be discussed at GE6.
A regional GLOSS meeting was held on 20 July 1998 at the Academia Sinica, Taiwan hosted by Prof.Shui-Beih Yu, in association with a meeting of the sea level group of the Asia Pacific Space Geodynamics project led by Prof.C.K.Shum from Ohio State University. The meeting benefitted from the attendance of many scientists at the Western Pacific Geophysics Meeting in Taiwan the following week. Further information on the GLOSS meeting can be found at:
http://www.pol.ac.uk/psmsl/gb6/pcs.html
This meeting followed hot on the heels of an Asia Pacific Space Geodynamics meeting in Tahiti at which C.K.Shum also took the opportunity to stimulate GLOSS-relevant activities. A report on that meeting is now available.
We also intend that there will be a GLOSS meeting at the IUGG in Birmingham in July 1999, probably held in association with the IAPSO Commission on MSL and Tides. I will be a co-convenor for one of the two main sea level sessions at the Birmingham conference.
TIDE GAUGE HARDWARE PROVISION
Four OTT tide-gauges provided by Sweden were sent by Germany to Nigeria, Guinee, Gambia and Cote d'Ivoire in 1996. A report is anticipated from Larry Awosika, the IOCEA GLOSS Regional Coordinator, on this matter. Latest news, however, is not encouraging with regard to their installation (see the 'ge5actions' list). This stresses that the provision of training courses and/or hardware is not necessarily enough to make progress.
A request for second-hand, but serviceable, tide gauge hardware was circulated by the PSMSL in 1998, and relayed to the correspondence list of the International Hydrographic Organisation (IHO). This resulted in the offer of 4 good Ott R20 gauges from Singapore, and the possibility of offers of others. This single kind donation from Singapore to GLOSS will result in at least two African countries (Madagascar, Ghana and one or two others) having 'new' gauges in 1999. The PSMSL and IHO intend to repeat the request in the near future. At the present time, POL intends to add shaft encoder data loggers to at least two of the Singapore gauges. However, in general, is second hand equipment worth the effort? Experiments at POL and in South Africa suggest that the Ott encoders may be a very cost effective option (less than 2K$) for many locations as a stand-alone system and, of course, they would be new, modern equipment with a guarantee. We hope that further information will be available at GE6.
TIDE GAUGE SCIENCE (E.G. IPCC)
As normal, there have been many science meetings at which sea level changes have been discussed. All relevant sea level meetings which I attend each year are summarised in the PSMSL Annual Reports (http://www.pol.ac.uk/psmsl/psmsl.info.html).
Numerous papers have been published using GLOSS (and sea level in general) data. The IPCC Second (1995) Scientific Assessment published in 1996 was most important in stressing the continued need for sea level measurements. The Third Assessment has now started with a sea level chapter led by Drs.John Church and Jonathan Gregory which all GLOSS Experts should provide input to.
CONTINUED DEVELOPMENT OF GLOSS-GOOS
Evidence that GLOSS objectives are being met (slowly maybe) can be obtained from the data holdings of the PSMSL and other centres (UHSLC, NTF/SOSLC etc.). Statistics such as those described above have been compiled each year and are given in the PSMSL Annual Reports. Discussions at meetings in Sydney and Paris of the Interim Implementation Advisory Group (IIAG) for GOOS, which includes GLOSS, during 1998 have demonstrated the need for a whole new range of sea level measurements for coastal applications, additional to the areas normally discussed in a GLOSS context. Consequently, there is likely to be a considerably enhanced requirement for training, advice and collaborative measurement activities in the future. How the resources for such work will be found is a major issue for discussion at GE6.
There have been a number of GLOSS regional activities started over the past decade (see Chapters 8 and 9 of the GLOSS Implementation Plan for short descriptions). However, there have not been enough of them and there is a major need for regional stimulation of GLOSS activities (see GE6 agenda). In my opinion, this is the single most important thing which would boost GLOSS, if a sufficient number of energetic regional activists can be found.
REQUESTS FOR NEW RESOURCES FOR GLOSS
IOC funds for GLOSS are extremely limited and tend to be devoted to the costs of meetings (e.g. those of the GLOSS Group of Experts), training courses (e.g. the University of Cape Town course) and sea level products (e.g. data and training CD-ROMs). There are virtually no funds for new gauges or geodetic equipment.
A course of action was initiated in 1998 in order to try to find new resources for GLOSS. Letters have been written to international companies (e.g. oil companies, tide gauge manufacturers) with interests in certain parts of the world for which GLOSS developments are required. The letters asked if interest exists in the companies to sponsor the training and/or provision of hardware to a young scientist, perhaps via a master's course. At the time of writing, it is too early to judge the success of such appeals. Suggestions have been made for investigating the foreign aid budgets of various countries. Other suggestions are welcome.
GLOSS FORWARD LOOK
It is interesting that during the two years under review that the most senior of the world's politicians were evidently doing good work on our behalf. At the Fourth Session of the 'UN Framework Convention on Climate Change, Conference of the Parties' in Buenos Aires 2-13 November, the following recommendations of the Subsidiary Body for Scientific and Technological Advice were approved (amongst others). Such recommendations could have been written with the PSMSL and GLOSS in mind, and give the highest possible lead to national authorities to provide the international community with the sea level and other data sets which it needs for research. When considered alongside the approval of the new GLOSS Implementation Plan by the IOC Assembly in 1997, GLOSS can be seen to, in principle, have the highest level backing in which to perform its work in coming years:
Following the retirement of Dr.Tolkatchev from IOC in 1997, and the reorganisation of the GOOS Office in Paris following the appointment of new Director, Dr.Colin Summerhayes, the role of GLOSS Technical Secretary has been occupied part-time until the end of 1998 by Mme.Janice Trotte from the Directoria de Hidrografia e Navegacao (DHN) in Brazil. Janice's work for GLOSS is very much appreciated by the Group of Experts. From January 1999, the position will be filled by Dr.Thorkild Aarup from Denmark, although contact with Janice will be maintained through her ongoing work for GOOS.
Relevant References
TSIMPLIS, M.N. & SPENCER, N.E. 1997. Collection and analysis of monthly mean sea level data in the Mediterranean and the Black Sea. Journal of Coastal Research, 13(2), 534-544.
IOC. 1997. IOC group of experts on the Global Sea Level Observing System (GLOSS), fifth session, Pasadena, California, USA, 19-21 March 1997. Intergovernmental Oceanographic Commission, Reports of Meetings of Experts and Equivalent Bodies, IOC/GE-GLOSS-V/3, 9pp. & annexes.
WOODWORTH, P.L. 1997. The Global Sea Level Observing System (GLOSS). GOOS News No.4, November 1997, pp.7-8. Published by the Intergovernmental Oceanographic Commission.
WOODWORTH, P.L. 1997. The Permanent Service for Mean Sea Level and the Global Sea Level Observing System. pp.55-62 in, Science Services. International Association of Geodesy (IAG) & Federation of Astronomical and Geophysical Services (FAGS). Presented at the IAG Scientific Assembly, Rio de Janeiro, Brazil, September 3-9, 1997. Published jointly by the Department of Civil and Environmental Engineering and Geodetic Science, The Ohio State University, Columbus, Ohio and the IAG Central Bureau, Department of Geophysics, University of Copenhagen, Denmark.
NEILAN, R., VAN SCOY, P.A. & WOODWORTH, P.L. (eds). 1998. Proceedings of the Workshop on methods for monitoring sea level: GPS and tide gauge benchmark monitoring, GPS altimeter calibration Workshop organised by the IGS and PSMSL, Jet Propulsion Laboratory, 17-18 March 1997. 202pp.
WOODWORTH, P.L. (ed.) 1998. Global Sea Level Observing System (GLOSS) Implementation Plan 1997. Intergovernmental Oceanographic Commission, Technical Series, No. 50, 91pp. & Annexes.
ALCOCK, G.A. & WOODWORTH, P.L. (organisers). 1998. Joint IOC-CIESM training workshop on sea-level observations and analysis for the countries of the Mediterranean and Black Seas. Proudman Oceanographic Laboratory, 16-27 June, 1997. Intergovernmental Oceanographic Commission Workshop Report No.133.
INTERNATIONAL SEA LEVEL WORKSHOP. 1998. Proceedings of the International Sea Level Workshop held at the University of Hawaii, 10-11 June, 1997. Published by the National Oceanic and Atmospheric Administration. 133pp.
WOODWORTH, P.L. & TROTTE, J. 1998. Sea level observing systems. Tiempo, Issue 30 (December 1998), 17-22.
SHUM, C.K, WOODWORTH, P. & SCHERER, W. 1998. Impact of sea level variations in the Asia-Pacific region, Science Working Group Report. pp.41-54 in, Proceedings of the Second International Meeting of the Asia-Pacific Space Geodynamics (APSG) Program, Tahiti, French Polynesia, 12-16 May, 1998.
BRUNDRIT, G.B. & WALDRON, H. 1999. IOC/GLOSS-GOOS training workshop on sea-level data analysis. University of Cape Town, 16-27 November, 1999. Intergovernmental Oceanographic Commission Workshop Report (in press).
Appendix 1: Non-Operational GLOSS Sites
GLOSS No. GLOSS Station Responsible Country 262 LOBITO ANGOLA 190 PUERTO DESEADO ARGENTINA 47 CHRISTMAS IS. AUSTRALIA 197 PORTO DE NATAL BRAZIL 153 LITTLE CORNWALLIS IS. CANADA 224 NAIN CANADA 261 POINTE NOIRE CONGO 166 I. DEL COCO COSTA RICA 227 DANMARKSHAVN, GREENLAND DENMARK 315 ITTOQQORTOORMIIT, GREENLAND DENMARK 2 DJIBOUTI DJIBOUTI 182 ACAJUTLA EL SALVADOR 165 CLIPPERTON IS. FRANCE 21 CROZET IS. FRANCE 131 DUMONT D'URVILLE FRANCE 204 LE ROBERT, MARTINIQUE FRANCE 24 ST. PAUL IS. FRANCE 209 PORT-AU-PRINCE/LES GAYES HAITI 41 NICOBAR INDIA 67 SORONG INDONESIA 240 CASTLETOWNSEND IRELAND 252 NOUADHIBOU (CAP BLANC) MAURITANIA 160 ISLA GUADALUPE MEXICO 282 TAN TAN MOROCCO 141 MOULMEIN MYANMAR 128 CHATHAM IS. NEW ZEALAND 134 SCOTT BASE NEW ZEALAND 232 BJORNOYA (BEAR ISLAND) NORWAY 295 GWADAR PAKISTAN 272 DARU PAPUA NEW GUINEA 64 VANIMO PAPUA NEW GUINEA 25 MIRNY (ANTARCTICA) RUSSIA 260 SAO TOME SAO TOME/PRINCIPE 256 ABERDEEN POINT SIERRA LEONE 6 HAFUN (DANTE) SOMALIA 7 MOGADISHU SOMALIA 20 MARION IS. SOUTH AFRICA 9 MTWARA TANZANIA 303 MASSACRE BAY,ATTU IS.,ALASKA U.S.A. 218 MIAMI (HAULOVER PIER) U.S.A. 3 ADEN YEMEN, P.D.R. 304 SOCOTRA IS. YEMEN, P.D.R.