Measurement of the solar irradiance
Responsible person: Didier Gillotay
Measurement of solar irradiance is essential in the Sun-Earth interaction with the atmosphere.
We exploit 6 ground stations covering Belgium and Luxemburg. They have been fully integrated in the UV-Visible monitoring network. The stations (Uccle, Redu, Oostende, Virton, Mol, Diekirch) provide UV-B, UV-A, and Visible sets of data of the solar irradiance reaching the Earth's surface. Their data are offered as a service 24/7.
It is crucially important to know the solar irradiance that reaches the top of the atmosphere. The Sun's electromagnetic radiation activates photo-processes (dissociation, absorption, ionization) that are wavelength dependent. These interactions are main drivers in terms of composition, thermal structure and dynamics of the atmosphere. BIRA-IASB is therefore participating in space-based irradiance measurements. SOLSPEC and LYRA are space qualified spectrometer and filters radiometers especially dedicated to these measurements from space. SOLSPEC was developed by the CNRS SA (France), IASB and the Observatory of Heidelberg (RFA). LYRA was developed by ROB. After 5 flights in space during the 80's and 90's, SOLSPEC was completely refurbished at IASB with new electronics, revised optics, and new mechanical interface. It was launched in Februrary 2008 as part of the SOLAR payload of the COLUMBUS European module on ISS. The aim is to publish a highly accurate solar spectrum in radiometric units, from the UV (165 nm) to the IR (3.09 µm), and to establish its variation during a solar cycle.
We will continue/expand its activities concerning irradiance measurements, both from the ground and in space.