The Particle Environment Monitor (PEM) on NASA's Upper Atmosphere
Research Satellite (UARS) measures the type, amount, energy, and
distribution of charged particles injected into the Earth's
thermosphere, mesosphere, and stratosphere. PEM consists of four
instruments: the ... Atmospheric X-Ray Imaging Spectrometer (AXIS),
the High Energy Particle Spectrometer (HEPS), the Medium Energy
Spectrometer (MEPS), and the Vector Magnetometer (VMAG).
The UARS PEM level 2 MEPS daily product (UARPE2MEPS) 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. MEPS data covers the rough 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 deg 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 deg latitude.
The MEPS data files are written in network binary format. For more
information please review the PEM MEPS data format guide.