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Weather Help

Automatic Weather Station (AWS)

As a millennium project, Dún Laoghaire Harbour re-commissioned the anemometer (wind speed and direction instrument) which is situated on the East Pier. The original building and anemometer date back to 1852 and it was in working order until April 1981 when recording paper became obsolete. An "Automatic Weather Station" (AWS) was established in the original building in 2000 to combine old with new under the theme of the "millennium". This AWS will also has the facility to read and display pressure and temperature readings.

AWS Close Up of instruments
Close up of the AWS weather instruments.

Since the AWS was established an additional visual display has been set up on the Marina East Breakwater and data is also received by the Royal National Lifeboat Institution, the RIYC and the Marina.

The project had a fourfold effect, namely:

  • Re-instate building to its original purpose.
  • To allow the general walking public on the pier to read the wind speed and direction and other data from a visual display.
  • To allow the Meteorological Service to have direct access to the AWS through a modem
  • To allow other users (Harbour Office, Stena Line etc.) to have direct access to the AWS.
Quote from Peter Pearson's 1981 book "Dún Laoghaire-Kingstown"
Automated Weather Station East Pier Dun Laoghaire Harbour
Anemometer on the East Pier

"The anemometer on the East Pier is yet another example of excellent masonry work. By monitoring wind and speed and direction, it made a significant contribution to safety at sea".

"The design was perfected by Professor Robinson of Trinity College, Dublin, and when built in 1852 was one of the first in the world. The little granite building which adopts a severe Greco-Egytian style is reminiscent of a family mausoleum".

It is also shown in cardinal points as follows:

The direction of the wind is the true bearing in degrees of the point from which it blows.

The wind speed is given in Nautical miles per hour - knots:

  • 1 knot = 1.853 kilometres per hour (km/h)
  • 1 knot = 1.152 miles per hour (mph)
  • 1 knot = 0.515 metres per second (m/s)

East Pier Automatic Weather Station

  1. The air temperature is given in degrees centigrade (°C).
  2. Humidity is the percentage of water vapour in the air.
  3. Relative humidity is the amount of moisture in the atmosphere as compared with that of complete      saturation ' given as a percentage.
  4. Dewpoint is the temperature to which the air can be cooled without causing condensation.
  5. The air pressure is expressed in hectopascals (hpa). Previously millibars (mb).
  6. Rainfall is expressed in millimetres (mm) and is automatically reset to zero at midnight.
  7. The geographical position is expressed in latitude and longitude.
  8. The wind gust is the highest recorded gust over a 15 second period.

The installation of the automatic weather station was a millennium project and was wholly funded by Dún Laoghaire Harbour Company.

Additional Information

Beaufort Wind Scale

Wind speed is given in miles per hour, or kilometers per hour, but you may often hear it referred to as a 'Force', with a number between 0 and 12. This is the Beaufort Scale, devised for sailing ships of the Royal Navy in 1806 by Admiral Sir Francis Beaufort, (1774 - 1857 ), and now an internationally recognised standard. Admiral Beaufort defined force 0 as 'calm' and force 12 as "that which no canvas could withstand". View the Beaufort Scale here with links to other resources.