Space weather observations with four SREM radiation monitors

The ESA Standard Radiation Environment Monitor (SREM) is a particle detector developed with the main purpose of permanent monitoring of the space radiation environment and providing alerts of radiation related hazards to the spacecraft and its payload. Four SREM instruments are launched onboard of PROBA-I, ROSETTA, INTEGRAL and recently GIOVE-B satellites. SREM offers fair spectral and directional sensitivity thus allowing for precise quantitative studies of the radiation environment in the Solar system. This includes Sun transient events like Solar Energetic Particles with their propagation through the interplanetary space, long-term measurements of Cosmic Ray fluxes, as well as dynamic mapping of the Van Allen radiation belts. (authors)