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.

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 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.

Points Of Interest - patrimonial elements contains point elements relating to the patrimony, namely (water and wind)mill, (historic, commemoration, fortified) building, historic mound, ice house, castle, kiosk, shoring, non-religious monument, monumental stairs in Belgium.

Annual temperature extremes given in number of days: 1/ Total number of heatwaves occurring once in 20 years; 2/ Maximum length of the heatwaves occurring once in 20 years; 3/ Hot days: Mean annual number of days with maximum temperature > 25°C; 4/ Tropical days: Mean annual number of days with maximum temperature > 30°C; 5/ Frost days: Mean annual number of days with minimum temperature < 0°C. Heatwaves are defined according to the Royal Meteorological Institute of Belgium when the maximum temperature in Uccle is >= 25°C during at least 5 consecutive days, during which at least 3 days the maximum temperature is >= 30°C. The temperature extremes are available for the present target year 1975, which corresponds to the middle of the 30-year period 1961-1990.

RADCLIM is a historical dataset based on weather radar observations that provides gridded accumulated precipitation composites over Belgium and surrounding regions. The data are distributed in ODIM_H5 version 2.2 format. The reported quantity is accumulated precipitation (ACRR) for 5-minute and 1-hour accumulation periods. UTC is used as the time reference, and the timestamp in the filename corresponds to the end of the accumulation period. The dataset is produced on a 700 × 700 grid with 1 km spatial resolution in the Belgian Lambert 2008 projection (Lambert Conformal Conic).