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Subsections

• General
• Data

IRM Prime Parameter Database

General

Processed data from IRM were originally stored at the UK Geophysical Data Facility at RAL, under a propriatary database system (R-EXEC). These data have subsequently been converted into Common Data Format (CDF) files, whose detailed design structure matches closely those intended for the Cluster mission and defined in DS-QMW-TN-0003 (available from http://www.space-plasma.qmw..ac.uk/). The database team decided to implement a faithful archive of the original GDF data. This has resulted in some anomalies, of which the most important, perhaps, is the interpretation of the timetags for the data. The GDF database labelled each datum with the start time of the data integration period, placed on exact $0, 5, 10, \ldots$ second boundaries. The Cluster specification is based on centred timetags, so that newly deposited data has a different definition of the timetags. Users should consult the Data Caveats page for accurate information, and may need to adjust the timetags for some purposes. Additionally, there are also differences in the way the IRM timetags were generated, including both mission operational and database generation aspects. In particular, the IRM data were calculated as spin averages. These were then forced onto uniform 5 second tags by averaging all (usually one) data within a 5-second interval. The consequence was to shift the timetags of many data points by a considerable fraction of a spin period. The original spin-averaged data are no longer available. These and other aspects of the IRM data are also detailed in the Data Caveats page.

The CDHF has not maintained the various catalogues used in conjunction with the GDF. An Appendix to this document describes all the IRM data variables.

IRM Prime Parameter data may be accessed using a WWW interface at http://XXX.XXX.XXXX/ and also through the client-server X-Chooser system available through the same WWW location.

Data

The databases contain files derived from all IRM instruments as outlined below. This product also contains a variety of house-keeping and ephemeris information. Vectors are stored in geocentric-solar-ecliptic (GSE) coordinates. Time tags on data records denote the start of a 5-second interval. Details of units, instrument modes, and other ``metadata'' information is held within the CDF files. Some of this information is repeated in an Appendix to this document.

• Magnetometer. 5 second mean values of the magnetic field
• Plasma instrument. 5 second samples of various moments of the ion distribution:
  • protons: total number density, number density for energies > 8 keV, temperature and velocity (in polar form: magnitude, flow latitude and flow longitude). The temperature, flow latitude and flow longitude are not available (set to null values) in the solar wind. The number density at high energies is not available at times when the instrument was operated in the so-called half-sweep mode.
  • electrons: total number density, number density for energies > 2 keV, and temperature. The number density and temperature are not available (set to null values) in the tail lobes.

• Wave spectrometer. 5 second mean and peak values of the power spectral density for both electric and magnetic waves at a variety of frequencies.
• Suleica. Fluxes of a variety of suprathermal ion species. These are available at an integration time of about 70 seconds but are stored as a 5 second time-series, i.e., typically 1 data value is followed by about 13 null values.

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