How we measure meteo factors
The various meteorological elements are derived from observations made by a meteorologist located in the control tower and from instrumental measurements made near the runways or at the airport's weather park.
Wind speed and direction are measured by four anemometers located near the runway threshold. Due to wind fluctuations, instantaneous values have no operational significance so we use the average values in combination with the extreme values measured over the last ten minutes: maximum "instantaneous" speed (gusts) and extreme directions (minimum and maximum heading). Wind forecasts are based on digital prediction models, analysed and validated by a meteorologist from skeyes’ meteorological prediction centre at Brussels Airport (MET Office EBBR).
The air temperature (in °C), dew point temperature (in °C) and atmospheric pressure (in hPa) are measured at the weather park, located near landing zone 25L.
The relative humidity (expressed in %) is calculated on the basis of air temperature and dew point measurements.
Visibility is estimated by the meteorologist who has a 360° panoramic view in the control tower and visibility sensors located along the runways.
Frequency of the different observations
- Air temperature: 1 minute
- Pressure: 1 minute
- Humidity: 10 minutes
- Dew point: 1 minute (per calculation)
- Wind: "continuous" measurement but:
- Calculation of the 10-minute average wind speed: 1 minute
- Calculation of gusts: 1 minute
- Visibility: continuous human observation, report of a new value every 30 minutes and when visibility changes and exceeds certain specified thresholds.