The National Observing Network

There are five manned weather stations in operation, Casement Aerodrome, Cork Airport, Dublin Airport, Knock Airport and Shannon Airport . These stations record meteorological elements on an hourly basis. Data are gathered by a meteorological observer and immediately translated into synoptic coding (which is the numerical code for reporting weather observations) and sent via computer to Met Éireann Headquarters (HQ) in Glasnevin, Dublin. See Figure 1.

Figure 1: 7441 form used by a meteorological observer to record synoptic coding for each observation.

These data are immediately used in the production of up-to-date weather forecasts. The elements recorded are:

• • Air temperature
  • Rainfall
  • Wind speed and direction
  • Atmospheric pressure
  • Relative humidity
  • Soil and earth temperatures
  • Past and present weather
  • Cloud type and height-Visibility
  • Sunshine

There are 20 fully automatic weather stations across the country recording meteorological elements on a minute-by-minute basis. These data are transferred back at hourly intervals via PSTN/broadband line to Met Éireann HQ. They are then analysed by computer programs and an hourly observation is created and translated into synoptic code. These, like the manual observations, are put to immediate use in forecast model runs. The weather elements recorded are the same as those recorded at manned synoptic stations. Automatic weather stations.

Figure 2: Automatic Weather Station at Malin Head, Co. Donegal.

Data from manned and automatic weather stations are supplemented by daily observations made at climatological stations. There are currently over 60 climate stations scattered across Ireland. These stations are run by a combination of voluntary observers and state agencies who record one daily reading at 0900 UTC. This weather information is logged on a climate form, which is sent to Met Éireann HQ by post at the end of each month. These data are then inputted into the Met Éireann database and quality controlled by Met Éireann staff for use in climate analysis and meteorological research.

Figure 3: Stevenson screen. This shields the meteorological instruments inside against precipitation and direct heat radiation.

Contents of a Stevenson Screen at a climatological station

All climate stations report air temperature and rainfall and some also report:

• Grass temperature
• Soil and earth temperatures
• Sunshine-Cloud
• Wind speed and direction
• Visibility
• Present weather

Distribution of rainfall over Ireland is extremely variable so it is important to have countrywide coverage of rainfall instrumentation. Currently there are around 500 rainfall stations across the country, strategically located. These stations, like climate stations, are run by a combination of voluntary observers and state agencies. There are two types of rainfall station; daily and monthly. Daily rainfall stations record rainfall data once a day at 0900 UTC. Rainfall readings at monthly stations are taken once a month at 0900 UTC on the first day of the following month. Both daily and monthly station data are logged on a rainfall card, which is then sent into Met Éireann HQ via post at the end of each month. These data go through the same process as the weather data received from climate stations by being inputted into Met Éireann’s database and quality controlled before being used elsewhere.

Rainfall card for a daily rainfall station which is sent into Met Éireann at the beginning of the next month.

In the future, all stations will eventually become automatic, resulting in more data readings improving meteorological research and climate analysis.