The ceilometer CL51 employs a pulsed diode laser LIDAR technology, where short, powerful laser pulses are sent out in a vertical or near-vertical direction. The reflection of light (backscatter) caused by clouds, precipitation or other obscuration is analysed and used to determine the cloud base height, the cloud layer height and the amount of clouds (in octas) in different layers.

An hillshade is a homogeneous and regular points grid, indicating the grey tone deriving from their orientation relative to the chosen fictitious light source. The Hillshade DTM 1m is a representation of the hillshading of the DTM 1m.

Hourly forecasts for each belgian commune, from current hour up to the next 5 days. This product is not publically available.

The composite is produced every 5 minutes using the reflectivity data from the Wideumont and Jabbeke weather radars. This product is not publicly available yet.

Bird density profiles are derived from weather radar volume data in real time, by the vol2bird algorithm as described in Dokter et al. (2011, 2019). The vol2bird algorithm exploits the radar reflectivity characteristics of different scatterers in the atmosphere, in order to distinguish biological from non-biological radar echoes. Once biological scatterers are isolated in the volume files, the reflectivity of these scatterers is converted in an estimate of the bird density per vertical layer of 200m, using a mean cross section of 11 cm2. The vbird profiles are provided for the following radars, with the radar owner in parentheses: Jabbeke (RMI), Wideumont (RMI), Helchteren (VMM), Zaventem (Skeyes), Herwijnen (KNMI), Den Helder (KNMI), Neuheilenbach (DWD), Essen (DWD), Abbeville (Météo-France) and Avesnois (Météo-France). References: - Dokter A.M., Liechti F., Stark H., Delobbe L., Tabary P., Holleman I., Bird migration flight altitudes studied by a network of operational weather radars, J. R. Soc. Interface, 8, 30–43, 2011, DOI 10.1098/rsif.2010.0116 - Dokter A.M., Desmet P., Spaaks J.H., van Hoey S., Veen L., Verlinden L., Nilsson C., Haase G., Leijnse H., Farnsworth A., Bouten W., Shamoun-Baranes J., bioRad: biological analysis and visualization of weather radar data, Ecography, 42, 852-860, 2019, DOI 10.1111/ecog.04028

Annual and seasonal precipitation indices given in number of days: 1/ Wet days: Number of days with precipitation > 0.1 mm/day for winter, autumn, spring, summer; 2/ Dry days: Number of days with precipitation < 0.1 mm/day for winter, autumn, spring, summer; 3/ Average length of dry spells: Mean duration of minimum three consecutive days with precipitation < 0.1 mm/day; 4/ Maximum length of dry spells: Longest period of minimum three consecutive days with precipitation < 0.1 mm/day, occurring once in 20 years. The precipitation indices are available for the future target year 2085, which corresponds to the middle of the 30-year period 2071-2100, and for mean and high impact scenarios corresponding respectively to the 50th, and 5th or 95th percentiles of the change factors.

The average household size of private households, by administrative unit (region, province, arrondissement and municipality) for Flanders

Govroam is a " wifi roaming " solution. This service offers to the users a simple and secure access to the wireless network of their institution, but also to networks of other participating institutions. A user from an organization that participates in govroam will be able to connect to any wireless access point broadcasting govroam. The data provided here makes it possible to locate these access points.

The number of inhabitants according to official statistics per age group of 5 years and gender by administrative entity (region, province, district and municipality) for Wallonia.

A climate normal is an average over a 30-years period. The period 1981-2010 is the current reference period recommended by the World Meteorological Organization (WMO). Recent climate normals are available for any locations in Belgium and several parameters including air temperature, precipitations and solar radiation. Climate normals for the reference period 1981-2010 are available for air temperature, precipitation and derived parameters (e.g., annual number of summer days, annual number of precipitation days, etc.). For solar radiation, the reference period had to be adjusted to 1984-2013 because of data availability. These climate normals are available as maps and as table for each Belgian municipality.