NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header

Advanced Composition Explorer Level 2 SWEPAM 1-Hour Solar Wind Plasma, ASCII


Availability: Archived at NSSDC, accessible from elsewhere

Time span: 1998-01-23 to 2000-07-01


This data collection contains hourly Level 2 data in ASCII format from the Solar Wind Electron, Proton and Alpha Monitor (SWEPAM) experiment on the Advanced Composition Explorer (ACE) spacecraft. The single data file contains all solar wind data from SWEPAM through the present end date of this data set with individual records averaged over one hour of data. Each record 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.

Data are available online at

Alternate Names

  • SWEPAM Level-2 1-hr SW Plasma,ASC


  • Space Physics: Heliospheric Studies


  • 97-045A-07F

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
Mr. Robert M. CandeyGeneral ContactNASA Goddard Space Flight
[] NASA Logo -