This set of plasma data came from the Retarding Potential Analyzer and
Ion Drift Meter instruments that constituted the San Marco Ion Velocitiy
Investigation (IVI). The data were submitted by the PI team in ASCII
format with SFDU Voldesc and Format description files. The data are
provided as monthly files. Each data record contains the following
parameters deduced from the IVI measurements: ion temperature, spacecraft
potential, vertical and horizontal component of the ion velocity, total
ion density, H+ ion density, O+ ion density, and the density of molecular
ions. In addition the following parameters are included with each record:
date, time, dip latitude, altitude, geographic longitude and latitude,
solar local time, and solar zenith angle. The time resolution is
approximately 10 seconds. The data have been screened for errors due to
lack of appropriate vehicle orientation information or to failure of the
least-squares analysis routine. More information about the satellite
mission, the IVI experiment and the format of the data can be found in
the voldesc and format files. Both files are ASCII text files.

Further details about the San Marco spacecraft, experiment, and data sets can be found at the San Marco home page, http://crpsm.psm.uniroma1.it/