The SEM-2 instrument is one of the non-meteorological instruments on Metop. It has been added to the set of American instruments in order to guarantee NASA/NOAA a continuity in the determination of auroral activity — intensities of charged particle radiation within the Earth's atmosphere that can degrade radio communications (occasionally making short wave radio communication impossible in the polar regions); occasionally disrupt the proper operation of satellite systems, and, when intensities are high, increase the radiation dose to astronauts in space.

The Space Environment Center (SEC) processes the particle counts received from Metop and monitors solar activity and the state of the Earth's near space environment. Warnings are issued to advisories and forecasts of conditions are relayed to customers whose systems are affected.