Mass Spectrometer Incoherent Scatter (MSIS) Model

The Mass-Spectrometer-Incoherent-Scatter (MSIS) model describes the neutral temperature and densities in the Upper Atmosphere (above about 100 km). MSIS-86 constitutes the upper part of the COSPAR International Reference Atmosphere (CIRA) 1986. The MSIS model is based on the extensive data compilation and analysis work of A.E. Hedin (GSFC, code 614) and his colleagues. Data sources include measurements from several rockets, satellites (OGO-6, San Marco 3, AEROS-A, AE-C, AE-D, AE-E, ESRO 4, and DE-2), and incoherent scatter radars (Millstone Hill, St. Santin, Arecibo, Jicamarca, and Malvern). The model expects as input: year, day of year, universal time, altitude, geodetic latitude and longitude, local apparent solar time, solar F10.7 flux (for previous day and 3-month average), and magnetic Ap index (daily or Ap history for last 59 hours). For these conditions the following output parameters are calculated: number density of He, O, N2, O2, Ar, H and N, total mass density, neutral temperature and exospheric temperature. For diagnostic purposes the source code is equipped with 23 flags to turn on/off particular variations. The model software is available from NSSDC on magnetic tape, diskette for use on PCs, and online over SPAN. The MSIS model can also be run online interactively on NSSDC's NODIS account.