Permanent Services

Permanent Service for Mean Sea Level

The Permanent Service for Mean Sea Level (PSMSL) is the internationally recognised global sea level data bank for long term sea level change information from tide gauges and also provides a wider Service to the sea level community.
The PSMSL was established in 1933 by Joseph Proudman who became its first Secretary. Since then, the PSMSL continues to be responsible for the collection, publication, analysis and interpretation of sea level data. It is hosted by the National Oceanography Centre (NOC), Liverpool with funding provided by the UK Natural Environment Research Council. PSMSL operates under the auspices of the International Council for Science (ICSU).

Director: Elizabeth Bradshaw, National Oceanography Centre, British Oceanographic Data Centre, UK

previous Director: Lesley J. Rickards, Proudman Oceanographic Laboratory, UK

IAPSO Liaison: Philip L. Woodworth, National Oceanography Centre, UK




  1. Activities Report 1991 - 1995
  2. Activities Report 1999-2003
  3. 2004 Annual Report
  4. 2006 Annual Report
  5. Activities Report 2003-2007
  6. Activities Report 2007-2011
  7. Activities Report 2011-2015
  8. Activities Report 2015-2017
  9. Activities Report 2017-2019
  10. PSMSL Update, Presentation of Andy Matthew to the GBM, Montreal July 2019
  11. Activities Report 2019-2022

IAPSO Standard Seawater Service

The IAPSO Standard Sea-Water Service is the only internationally recognized standard for the calibration of salinity measurement devices. Its widespread use over 100 years of IAPSO history has been of great importance to the quality and comparability of salinity data worldwide. IAPSO continues to oversee the preparation of standard sea water and to encourage its use by all laboratories involved in salinity measurement. Demand for this service continues to grow.
Initially, the standard sea-water was prepared under the guidance of the International Council for Exploration of the Seas, Copenhagen. In the early 1970's the operation was transferred to the Institute of Oceanographic Sciences (IOS) in England. In 1989, with IAPSO's concurrence, a private company (Ocean Scientific International Limited) was set up with space and facilities provided by IOS. As a result, ampoules of standard sea-water continue to be available to the oceanographic community thorough this IAPSO service.

Director: Richard Williams

Contact: IAPSO Standard Seawater Service, OSIL
Havant, United Kingdom
E-mail: osil(at)



  1. Activities Report 1991-1995 
  2. Activities Report 2009-2013
  3. Activities Report 2013-2017
  4. Activities Report 2017-2019
  5. Activities Report 2019-2023




To promote the study of the oceans and the interactions that take place at its boundaries with the sea floor, coastal environment and atmosphere, through the use of physics, chemistry, mathematics and biogeochemisty.


IAPSO gives importance to involving scientists and students from developing countries in oceanographic activities.


  • Biennial scientific assemblies
  • Working groups
  • Committees, commissions and services
  • Website information

© Copyright © 2022 IAPSO. All Rights Reserved.

We use cookies
This website uses only technical cookies to ensure optimal navigation. See the cookie policy for more information.