This Automatic Weather Station logged various parameters of weather data and displayed the results in almost real time. The sensors measured: Air temperature, Ground temperature at 1 metre depth, Rainfall, Barometric pressure, Sunshine, Wind speed and wind direction.
Some of the instruments are highlighted below. The AWS provided data from 5th September 2001 at 12 noon until 5th July 2006 at 11am, except for the wind measurements, which began on 8th August 2001 at 11:33am and ended on 5th July 2006 at 11:08am. It was superseded by a new AWS some two weeks later; on 21st July 2006. Full dataset (climate.armagh.ac.uk)
Rainfall Sensor
The Rainfall Sensor was mounted in UV-stable plastic and was aerodynamically shaped to reduce the effects of wind. The rain was collected by a funnel having an outer diameter of 80mm, therefore, 5 ml of rain water represents 1 mm of rainfall.
The Rainfall Sensor measured the amount of rainfall passing through it by means of an infra-red optical system. This rain gauge has since been removed from the Met Enclosure and is missing from the line-up on the right.
Sunshine Sensor
The sensor was manufactured from anodised aluminium with a laboratory glass dome. The unit was fully sealed against the ingress of moisture and sturdily built to withstand the most adverse weather.
Comparing direct sunlight with shade the sensor produced a pulse every 36 seconds (0.01 hour) when the ratio exceeded a certain pre-set level ensuring that the output was independent of time of day or season, giving excellent results within a few minutes of dawn or dusk.
It was located on top of the sunshine tower, on a pole behind the Campbell-Stokes sunshine recorder, in front of the wind sensor.
Wind Sensor
The combined Wind Speed and Direction Sensor was manufactured from anodised aluminium alloy, UPVC and stainless steel with moulded polypropylene cups.
Wind Direction was sensed by a precision conductive plastic potentiometer which provided exceptional accuracy and high sensitivity.
Wind Speed was derived from a Hall Effect solid state magnetic switch activated by magnets in the cup rotor running in precision stainless steel ball race providing very high sensitivity.
Hardware and Software
The Automatic Weather Station was supplied by Instromet and the logging and display software was developed in-house using PERL programming language.
