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LANL 2002 Magnetospheric Plasma Analyzer (MPA) at 87 sec Resolution in Spacecraft Coordinates

Metadata Updated: August 30, 2025

The LANL 02A MPA data set contains numerical moments computed from measurements of the Los Alamos Magnetospheric Plasma Analyzer (MPA) [Bame et al., Rev. Sci. Inst., in press 1993]. The moments are presented in s/c coordinates: the z-axis is aligned with the spin axis, which points radially toward the center of the Earth; the x-axis is in the plane containing the spacecraft spin axis and the spin axis of the Earth, with +X generally northward; and the y-axis points generally eastward. Polar angles are measured relative to the spin axis (+Z), and azimuthal angles are measured around the z-axis, with zero along the +X direction. The moments are computed for three 'species': lop (low-ener. ions, ~1eV/e-~130eV/e); hip (hi-ener. ions, ~130eV/e-~45keV/e); alle (electrons, ~30eV - ~45keV ). The electron measurements are obtained 21.5 secs after the ion measurements. Epoch is the measurement time appropriate for the ions. The moments are computed after the fluxes are corrected for background and s/c potential. Algorithms for these corrections are relatively unsophisticated, so the moments are suspect during times of high background and/or high spacecraft potential. Because the determined spacecraft potential is not very precise, the magnitude of the low-energy ion flow velocity is probably not accurate, but the flow direction is well determined. Tperp and Tpara are obtained from diagonalization of the 3-dimensional temperature matrix, with the parallel direction assigned to the eigenvalue which is most different from the other two. The corresponding eigenvector is the symmetry axis of the distribution and should be equivalent to the magnetic field direction. The eigenvalue ratio Tperp/Tmid, which is provided for each species, is a measure of the symmetry of the distribution and should be ~1.0 for a good determination. Several of the parameters have a fairly high daily dynamic range and for survey purposes are best displayed logarithmically. These parameters are indicated by non-zero 'SCALEMIN' values in this file. A quality flag value of 1 indicates that the values are suspect because of unreliable location info.

Access & Use Information

Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Dates

Metadata Created Date April 11, 2025
Metadata Updated Date August 30, 2025

Metadata Source

Harvested from NASA Data.json

Additional Metadata

Resource Type Dataset
Metadata Created Date April 11, 2025
Metadata Updated Date August 30, 2025
Publisher NASA Space Physics Data Facility (SPDF) Coordinated Data Analysis Web (CDAWeb) Data Services
Maintainer
Identifier https://doi.org/10.48322/z6y7-r007
Data Last Modified 2025-08-27
Category Heliophysics
Public Access Level public
Bureau Code 026:00
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id 7e17b5d1-8000-41d1-aaba-a82a3f9190ff
Harvest Source Id 58f92550-7a01-4f00-b1b2-8dc953bd598f
Harvest Source Title NASA Data.json
Homepage URL https://doi.org/10.48322/z6y7-r007
Program Code 026:000
Source Datajson Identifier True
Source Hash f3cf36522918e7309347bbcf87844d3d16671ba7618630c9ba8a261d37064be9
Source Schema Version 1.1
Temporal 2003-10-29/2008-01-03

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