ISO 16457:2022 pdf – Space environment (natural and artificial) — The Earth’s ionosphere model — International reference ionosphere (IRI) model and extensions to the plasmasphere.
1 Scope This document provides guidance to potential users for the specification of the global distribution of ionosphere densities and temperatures, as well as the total content of electrons in the height interval from 50 km to 1 500 km. It includes and explains several options for a plasmaspheric extension of the model, embracing the geographical area between latitudes of 80°S and 80°N and longitudes of 0°E to 360°E, for any time of day, any day of year, and various solar and magnetic activity conditions. A brief introduction to ionospheric and plasmaspheric physics is given in Annex A. Annex B provides an overview over physical models, because they are important for understanding and modelling the physical processes that produce the ionospheric plasma. 2 Normative references There are no normative references in this document. 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminology databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https:// www .iso .org/ obp — IEC Electropedia: available at https:// www .electropedia .org/ 3.1 ionosphere region of the Earth’s atmosphere in the height interval from 50 km to 1 500 km containing weakly ionized cold plasma 3.2 plasmasphere torus of cold, relatively dense (> 10 cm −3 ) plasma of mostly H + in the inner magnetosphere, which is trapped on the Earth’s magnetic field lines and co-rotates with the Earth Note 1 to entry: Cold plasma is considered to have an energy of between a few electronvolts and a few dozen electronvolts. 3.3 plasmapause outward boundary of the plasmasphere (3.2) located at between two and six Earth radii from the centre of the Earth and formed by geomagnetic field lines where the plasma density drops by a factor of 10 or more across a range of L-shells of as little as 0,1
3.4 solar activity series of processes occurring in the Sun’s atmosphere which affect the interplanetary space and the Earth Note 1 to entry: The level of solar activity is characterized by indices. 3.5 ionospheric storm storm lasting about a day, documented by depressions and/or enhancements of the ionospheric electron density during various phases of the storm Note 1 to entry: Ionospheric storms are the ultimate result of solar flares or coronal mass ejections, which produce large variations in the particle and electromagnetic radiation that hit Earth’s magnetosphere and ionosphere (3.1), as well as large-scale changes in the global neutral wind, composition and temperature. 3.6 sunspot number R daily index of sunspot activity defined as k(10 g + s) where s is the number of individual spots, g is the number of sunspot groups, and k is an observatory factor Note 1 to entry: R is alternatively called Ri or Rz or SSN. Note 2 to entry: R12 is 12-month running mean of monthly sunspot number. Note 3 to entry: In 2014 the calculation scheme for the officially distributed sunspot number was changed  with the result that the new sunspot number (SSN2) is about a factor of 1,45 larger than the old one (SSN1). 3.7 F10.7 solar radio flux at 10,7 cm wavelength measured at the ground daily at noon Note 1 to entry: Besides this ‘observed’ F10.7 index there is also an ‘adjusted’ F10.7 index that is adjusted to 1AU. Often used averages are the 81-day (3 solar rotations) running mean and the 12-month running mean. 3.8 Lyman-α index solar activity (3.4) index based on daily measured solar emission at 121,6 nm (H Lyman-α line) 3.9 MGII index solar activity (3.4) index based on core-to-wing ratio of the magnesium ion h and k lines at 279,56 nm and 280,27 nm 3.10 Kp index planetary three-hour index of geomagnetic activity characterizing the disturbance in the Earth’s magnetic field over three-hour universal time (UT) intervals