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.

Hail products are derived from the observed vertical profiles of radar reflectivity and the NWP vertical profiles of temperature. Three types of products are generated. poh : probability of hail of any size (larger than 0.5 cm diameter)expressed in %. posh : probability of severe hail(larger than 2cm)expressed in %. mesh : maximum expected size of hailexpressed in mm of hailstone diameter. All products are generated every 5 minutes. This product is not publically available yet.

The number of private households according to official statistics, per administrative unit (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.

Annual, summer and winter mean potential evapotranspiration given in respectively mm/year and mm/3 months and based on the Penman-Monteith definition. The potential evapotranspiration fields are available for the present target year 1975, which corresponds to the middle of the 30-year period 1961-1990.

The entities included in the dataset represent the physical network in the sense of the Inspire European directive. The dataset comprises several classes and is in accordance with the INSPIRE specifications. The Wetland class represents poorly drained or periodically flooded portions of land, the soil of which is saturated with water but where vegetation is nevertheless able to develop. The StandingWater class represents flooded areas that are, nevertheless, completely surrounded by land.

The DTM 1m, digital terrain model at 1m-resolution, is a homogeneous and regular point grid indicating the height of the ground level in order to model its surface, without taking into account objects on the surface such as buildings and vegetation. DTM 1m is achieved by interpolating in Lambert 2008 source data in Lambert 72 and at a 1m-resolution from the Flemish (2013-2015) and Brussels (2021) Regions, and by adding Lambert 2008 data at 1m-resolution from the Walloon Region (2021-2022).

UV Index derived from spectral measurements with a Brewer UV spectrophotometer. This product is not publically available yet.

This dataset comprises historical orthophotos from the 1950s to 1959, derived from aerial surveys carried out by the National Geographic Institute (NGI). The ground sample distance (GSD) of the images is 50 cm. The mosaics were created using aerial photography campaigns dating from 1951, 1952 and 1954. The original photographs were digitised and orthorectified in the Lambert 2008 coordinate system. The spatial coverage for each year corresponds to the areas for which photographs were available. High-resolution data can be ordered via https://shop.ngi.be/fr/photos-aeriennes/

Summer and winter mean wind speed given in m/s. The wind speed fields 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 95th percentiles of the change factors.