The Particle Environment Monitor (PEM) level 2 Medium-Energy Particle Spectrometer (MEPS) daily product contains the electron and proton high-resolution spectral data converted to number intensity units from the MEPS sensors mounted on both the zenith and nadir UARS booms. PEM was flown on the UARS spacecraft to measure the type, amount, energy, and distribution of charged particles injected into the Earth's thermosphere, mesosphere, and stratosphere.

The PEM MEPS data covers roughly the energy range from 1 eV - 5 eV to 32 keV, where the lower energy cutoff is determined by internal instrument protection potentials. There are five analyzers mounted in different directions on the zenith boom, each of which contains an electron and ion sensor. These analyzers are mounted at -23.7 deg, +6.3 deg, +21.3 deg, +36.3 deg, and +66.3 degrees with respect to the spacecraft -z axis and along the spacecraft +y axis. There are three analyzers mounted in different directions on the nadir boom, each of which contain only an electron sensor. These analyzers are mounted at -158.7 deg, +156.3 deg, and +126.3 deg, with respect to the spacecraft -z axis and along the spacecraft +y axis. All MEPS analyzers accumulate a spectrum in 2.046 sec.

There is one data file per day for the PEM MEPS product, and the temporal coverage is from Oct. 1, 1991 to Aug. 23, 2005. Spatial coverage for the MEPS product ranges between -57 and +57 degrees latitude. The MEPS data files are written in network binary format. For more information please review the PEM MEPS data format guide.