The Cluster Ion Spectrometry (CIS) data products include three-dimensional ion distributions (about 0-40 keV/e) in 4-s spacecraft spin resolution and mass-per-charge composition distribution that are measured by the Hot Ion Analyzer (HIA) and Composition Distribution Function (CODIF) analyzer on board the Cluster II Tango spacecraft. Data products consist of processed raw data (Level 1 data), moments of the distribution functions (Level 2 data), and calibrated high-resolution data in a variety of physical units (Level 3 data). Furthermore, the calibration files and high-level processing software are also available.

CIS Level 1 data are decommutated, decompressed and time-tagged telemetry data in raw instrument units.

CIS Level 2 data are moments of the particle functions: ion density, velocity in the GSE reference frame, and temperature in parallel and perpendicular components (obtained by diagnolizing the pressure tensor). For CODIF, which has a higher upper energy limit than HIA, the pressure is also supplied in addition. They correspond to the Prime Parameters from the Cluster Science Data System: onboard calculated moments, then reprocessed on ground (total efficiency calibration adjustments, coordinate transformations etc.). Onboard calculated moments provide 1-spin time resolution, and are calculated from the full angular and energy resolution 3-D ion distributions.

In addition to the onboard calculated moments, CIS Level 2 data include also CODIF moments calculated on the ground from the 3-D ion distributions. These provide better calibration adjustments (per anode efficiency) and are thus more accurate, but have a reduced time and energy resolution. HIA on the ground calculated moments are not supplied, because the same anode calibrations would be used as for the onboard calculated ones, but with a degraded time, energy and angular resolution (no added value). A software package is available for download at the CAA web site, allowing the user to interactively calculate partial (or total) moments of the ion distributions, for selected energy and solid angle ranges: CODIF (all 4 ion species) and HIA data.

CIS Level 3 data are processed high-resolution 3-D ion distributions. They are produced by correcting the Level 1 data for detector efficiencies, geometric factors and other information available from the calibration tables, and give measurements in 5 physical units in separate files: (Differential) particle flux as ions cm−2s−1sr−1keV−1, (Differential) particle energy flux in keVcm−2s−1sr−1keV−1, particle phase space density in ions s3 km− 6, corrected-for-efficiency particle count rate as ions s**− 1, and raw particle counts in number of ions per counter bin. These Level 3 archival files are constructed by joining files from similar telemetry data products (same ion species, different angular, energy or time resolution). They are organized as a function of the instrument (HIA or CODIF), the operational mode (magnetospheric, solar wind, or RPA), the instrument sensitivity side (High Sensity or Low Sensity), and the 4 ion species of H+, He+, He++, and O+ with energies from ~25eV/e to 40 keV/e and with medium angular resolution of 22.5 deg (for CODIF only).

Two data processing software packages are available from CAA: the CIS_3D_MOM written in C to read the CIS Level 3 files, and another software written in IDL to read Level 1 data and calibrations files. The second software can read, in addition to CIS data, generic CDF and CEF data files for correlation studies.

The CIS data archive at CAA also includes experiment documentation, graphical products for browsing through the data, and data caveats.

For more details, see "The Cluster Active Archive: Studying the Earth's Space Plasma Environment", edited by Dr. Harri Laakso, Matthew G. T. T. Taylor, C. Philippe Escoubet, from which this information was obtained.