The Global Sea Level Observing System (GLOSS) is a programme coordinated by the Intergovernmental Oceanographic Commission (IOC) for the establishment of global and regional sea level networks. The main component of GLOSS is the 'Global Core Network' of 287 stations around the world for long term climate change and oceanographic sea level monitoring.

The Figure below shows sites in Africa in the GCN (ignore the various symbols for the moment). It can be seen that major sites were identified by GLOSS working groups, with approximately 500 km spacing between them and with locations of oceanographic interest (e.g. Straits of Gibraltar) included. This set of stations is clearly not enough to satisfy the complete set of scientific and practical requirements. However, it is at least a starting baseline around which proposals for regional densification can take place. Two examples of densification include the network of island stations in the Western Indian Ocean, and plans for stations on the North African coast as part of the MedGLOSS programme of IOC and the International Commission for the Scientific Exploration of the Mediterranean Sea (CIESM).  

Category 1: 'Operational' stations for which the latest data is 1996 or later;
Category 2: 'Probably operational' stations for which the latest data is within the period 1986-1995;
Category 3: 'Historical' stations for which the latest data is earlier than 1986;
Category 4: For which no PSMSL data exist.

It can be seen that there are only four Category 1 stations outside of East and Southern Africa and Indian and Atlantic islands, in spite of GLOSS being a mature programme commencing in the mid-1980s. Two of these (Ceuta and Las Palmas, Canary Islands) are in full operation. A third is in operation at Dakar, Senegal. However, there is some doubt as to the quality of its long-term maintenance. The gauge at Lagos, Nigeria was destroyed by a recent storm.

The figure does not provide the only test of 'operational status' and other assessments can be found in GLOSS documentation (e.g. in the report of the 6th GLOSS Experts meeting in 1999, see above PSMSL training page). However, we do believe that it gives a reliable general impression of the status of sea level recording in Africa.

A further indicator of the status of the programme concerns the availability of Global Positioning System (GPS) receivers at or near gauges to monitor vertical land movements, and thereby to identify the separate contributions of land and 'real' sea level changes in the gauge records. An up-to-date survey of GPS installations at gauges can be found at http://sonel.ensg.ign.fr/stations/cgps/surv_update.html.

This shows that an encouraging start has been made, with stations in, for example, South Africa (several locations), Egypt, Cape Verde Is. and Ceuta (Spain) (one station each). However, many more are required.

From these various assessments of programme status in Africa, it is clear that much work remains to be done.