The Down-welling Long-wave Radiation (DLR) flux (W.m-2) is defined as the thermal irradiance reaching the surface in the thermal infrared spectrum (4 - 100 µm). It is determined by the radiation that originates from a shallow layer close to the surface, about one third being emitted by the lowest 10 meters and 80% by the 500-meter layer.

The DLR is derived from several sensors (METEOSAT, MSG) using various approaches, in the framework of projects :
  GEOLAND
  AMMA