Advanced Composition Explorer (ACE) Solar Wind Electron, Proton, and Alpha Monitor (SWEPAM) Level 2 Data

The Solar Wind Electron, Proton, and Alpha Monitor (SWEPAM) measures
the solar wind plasma electron and ion fluxes (rates of particle flow)
as functions of direction and energy. These data provide detailed
knowledge of the solar wind conditions and internal state every
minute. SWEPAM also provides real-time solar wind observations which
are continuously telemetered to the ground for space weather purposes.

Electron and ion measurements are made with separate sensors. The ion
sensor measures particle energies between about 0.26 and 36 KeV, and
the electron sensor's energy range is between 1 and 1350 eV. Both
sensors use electrostatic analyzers with fan-shaped
fields-of-view. The electrostatic analyzers measure the energy per
charge of each particle by bending their flight paths through the
system. The fields-of-view are swept across all solar wind directions
by the rotation of the spacecraft.

WEPAM level 2 data is organized into 27-day time periods (Bartels
Rotations - roughly one solar rotation period). For each Bartels
Rotation, the level 2 data contains time averages of solar wind
parameters over the following time periods:

- 64 seconds (ion data only)
- 128 seconds (electron data only)
- hourly
- (all data) daily
- (all data) 27 days (1 Bartels rotation) (all data)

SWEPAM level 2 data consists of the following data items:

- Ion data
o Proton Density (np in cm -3)
o Radial Component of the Proton Temperature (TP,rr in o Kelvin)
o Ratio of Alpha Density to proton Density (nHe/nP)
o Proton Speed (VP in km/s)
o Proton Velocity Vector in GSE coordinates (in km/s)
o Proton Velocity Vector in RTN coordinates (in km/s)
o Proton Velocity Vector in GSM coordinates (in km/s)

- Electron data
o Electron Temperature (in o Kelvin) (not yet available)

See:
http://www.srl.caltech.edu/ACE/ASC/level2/swepam_l2desc.html