Western Channel Observatory

NERC National Capability of the Plymouth Marine Laboratory and Marine Biological Association


L4 Autonomous Buoy

As part of the NERC Oceans 2025 programme in 2007, PML were awarded a capital grant to build autonomous buoys for the long-term stations at L4 and E1. The L4 buoy is equipped with an array of sensors to look at both atmospheric and marine parameters. These include sea surface temperature, salinity, oxygen, turbidity, fluorescence (WetLabs WQM); air temperature, humidity, windspeed and direction and atmospheric pressure (AirMar); CDOM fluorescence (WetLabs); nitrate (Satlantic ISUS) and a hyperspectral radiometer (Satlantic). All these are controlled using a Satlantic StorX logger. An onboard Linux PC104 system controls dataflow and transmission to shore using a radiomodem link back to Rame Head. The current data rate is once per hour and data is transmitted every three hours to save on power. The buoys automatically report their position using AIS. The latest in-field data, which is strongly limited by data transmission volumes, are shown in the table below.

The L4 buoy is available to use as a platform for technological development. Recent collaborations have been with Witt Energy and Peak Design Ltd (Delta-T instruments). Data from the SPN1 Sunshine Pyranometer, which measures Global (Total) and Diffuse solar radiation from 400-2700 nm, can be seen below. The instrument is being evaluated for its suitability for use at sea.

Webcam L4

Webcam L4 image

Latest Buoy Position

Latest L4 data readings (50°15.0'N; 4°13.0'W)

Buoy automatic position given as DD.MMm where:

DD degrees, MM minutes, m decimal minutes

Latitude: 0.000 °Longitude: 0.000 °
Wind direction: 35.1 °Sea temperature: 0.0 °C
Wind speed: 2.5 ms-1Salinity: 0.00
Pressure: 15 mb Oxygen: 0.0 μM
PAR: 0 W m-2Chlorophyll: 0.00 mg m-3
Air temperature: 24.9 °CTurbidity: 0.00 NTU

Last Reading taken at: 0.00 GMT on 0/0/0

* Readings of -10 indicate missing data

Click here to download preliminary data and view latest systems log. Final, quality controlled data are available on request. The meteorological parameters for this buoy (6200030) are validated by Meteo France

Last 7 days met data

Windspeed and direction

Windspeed and direction chart


Pressure chart

Air temperature and PAR

Air temperature and PAR chart

Global and Diffuse radiation

Global and diffuse irradiance chart

Temperature and Salinity

Temperature and Salinity chart

Fluorescence and Turbidity

Oxygen, Fluorescence and Turbidity chart

Oxygen, CDOM and Nitrate

Nitrate and CDOM chart

About Us

The WCO is a partnership between the Plymouth Marine Laboratory and the Marine Biological Association.

How are we funded?

The core work of the WCO is funded as part of the UK Natural Environment Research Council's National Capability.

Contact Information

For more details about the WCO please contact:

Dr Tim Smyth
Western Channel Observatory
Plymouth Marine Laboratory
Prospect Place
email: tjsm@pml.ac.uk