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View MPA Spectrograms and MomentsMPA Data Description
- Geosynchronous Plasma Regimes
Ion and Electron Spectrograms
Moments- Permissions
Geosynchronous Plasma Regimes
The MPA instruments sample many types of plasma at geosynchronous orbit. These plasma environments include the plasmasphere, the plasmasheet, the trough, the magnetosheath, the low latitude boundary layer, and the lobe. Here is a plot of the occurence frequency of MPA observations of these different plasma regimes as a function of local time (from McComas et al., 1993).
Ion and Electron Spectrograms
MPA electron and ion fluxes are displayed in three different spectrogram formats:
This 24-hour sample spectrogram shows the different plasma environments encountered at geosynchronous orbit on February 25, 1992. The top four panels show the color-coded log of the ion count rate measured in each of the four azimuth quadrants, and the bottom panel provides the electron count rate averaged over a complete spin. Time is displayed along the x-axis and the log of the particle energy is displayed along the y-axis (~1 eV - 40 keV).
view MPA spectrograms and momentsMoments
The three-dimensional count matrices are converted to electron and ion distribution functions f(v). From these functions high- and low-energy electron and ion moments are calculated. For ions the ranges are ~1 eV - 100 eV and ~100 eV - 40 keV; and for electrons the ranges are ~1 eV - 30 eV and ~30 eV - 40 keV. In addition to density and temperature, the direction of the magnetic field can be determined from the symmetry axis of the particle distributions. The polar angle theta is measured between the symmetry axis and the spacecraft spin axis, and the azimuth angle phi is measured about the spin axis (relative to geographic north). The moments plots also include a measure of the penetrating background.
view MPA spectrograms and momentsPermissions
The MPA data should not be used for publication or public presentation without the express permission from the MPA team. For such permission or for additional information regarding the instrument or data, contact Michelle Thomsen (mthomsen@lanl.gov).
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