IRI 86 and MSIS 86 models updated

The International Reference Ionosphere (IRI) is the empirical standard model of ionospheric plasma densities and temperatures, sponsored by the Union Radio Scientifique Internationale (URSI)/Committee on Space Research (COSPAR). An international task group is in charge of updating the model, incorporating new measurements, and releasing improved editions. IRI 86 is based on the decisions made at the Louvain‐la‐Neuve workshop (see the “International Reference Ionosphere Status 1985–1986” issue of Advances in Space Research, vol. 5, no. 10, 1985) and was released at the Toulouse (France) COSPAR meeting (to be published in an upcoming issue of Advances in Space Research, 1987). The Mass Spectrometer Incoherent Scatter (MSIS) neutral atmosphere model was developed and updated by Hedin et al. [1977] and Hedin [1983, 1987]. The model describes the global and temporal variations of neutral densities and temperatures in the upper atmosphere. Its data sources include measurements from several rockets, satellites, and incoherent scatter radars. MSIS 86 will also constitute the upper part of the COSPAR International Reference Atmosphere (CIRA), following the decisions made at last year's COSPAR meeting in Toulouse.