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Advanced Composition Explorer Level 2 SWEPAM 27-Day Solar Wind Plasma, HDF


Availability: At NSSDC, Ready for Offline Distribution (or Staging if Digital)

Time span: 1998-01-23 to 2000-07-01


This data collection contains 27-day (Bartels) averaged Level 2 data in NCSA Hierarchical Data Format (HDF) from the Solar Wind Electron, Proton and Alpha Monitor (SWEPAM) experiment on the Advanced Composition Explorer (ACE) spacecraft. All data are included in one HDF file with a filename including the first and last Bartels intervals. Each data record for consecutive 27-day intervals contains solar wind proton density (cm-3), radial component of the proton temperature (Kelvin), alpha/proton density ratio, and proton speed (km/s). Electron temperature will later be included but is not yet available. The proton velocity vector components (km/s) are given in Geocentric Solar Ecliptic (GSE), Heliographic (RTN), and Geocentric Solar Magnetospheric (GSM) coordinates. The ACE spacecraft position is included in GSE and GSM coordinates. A data value of -9999.9 indicates bad or missing data for the given time period. Release notes on Level 2 processing are given in the text file swepam_release_notes.txt.

This collection is available on-line at:

Alternate Names

  • SWEPAM Level-2 27dy SW Plasma,HDF


  • Space Physics: Heliospheric Studies


  • 97-045A-07D

Additional Information



Questions and comments about this data collection can be directed to: Dr. John F. Cooper



NameRoleOriginal AffiliationE-mail
Dr. Andrew J. DavisGeneral ContactCalifornia Institute of
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