Permanent Service for Mean Sea Level | National Oceanography Centre

What is the Permanent Service for Mean Sea Level?

Permanent Service for Mean Sea Level (PSMSL) is the world's main hub for monthly mean sea level data. It provides the international sea level community with essential data, a range of derived products, and expert advice.

Elizabeth Bradshaw

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PSMSL is based at the National Oceanography Centre's (NOC) site in Liverpool, and we're committed to supporting its vital work for the long term. NOC is an independent, self-governing organisation, a charitable company funded by UK Research and Innovation to carry out National Capability programmes.

Visit the PSMSL website for more information

What are PSMSL's main activities?

PSMSL doesn't work in a bubble. It draws on the wide range of expertise we have here at the NOC, like the deep technical knowledge of our engineering teams.

PSMSL's work focuses on a few key areas:

Providing Data

Offering free access to mean sea level and delayed-mode datasets online, along with all the supporting information you might need.

Training and Development

Creating training materials and run courses for tide gauge operators and the people who use their data.

Sharing Information

Responding to requests for information from a wide range of people, including national tide gauge agencies, decision-makers in government, the media, and the public.

What is PSMSL's role in the global community today?

PSMSL continues to be a vital part of the international scientific community. It's a permanent service of two of the IUGG's unions (for Oceanography and Geodesy) and serves as a key data centre for UNESCO's Intergovernmental Oceanographic Commission's (IOC) Global Sea Level Observing System (GLOSS). It is also a regular member of the World Data System (WDS).

Get the Data

Looking for global sea level data or training on tide gauge operations? Visit psmsl.org explore datasets, find training resources, and see all the services supporting the international sea level community.

The history of the PSMSL

The story of PSMSL goes all the way back to 1933, at the International Union of Geodesy and Geophysics (IUGG) General Assembly in Lisbon. It was there that Professor R. Witting highlighted the need for international cooperation, stating:

"For the study of the tides and the tidal currents, of other movements of the sea surface and of currents of different origin, continual observations of sea level are the sole or a most valuable basis. For the solution of a complex of geophysical problems, data regarding sea level and its changes are of great importance."

Following this call to action, Joseph Proudman, who became PSMSL's first director, was tasked with the important job of collecting and publishing mean sea level data from sites all around the world.