Parameterized Ionospheric Model (PIM)

ars_thumb The Parameterized Ionospheric Model (PIM) is a fast global ionospheric and plasmaspheric model based on a combination of the parameterized output of several regional theoretical ionosphere models and anempirical plasmaspheric model. It represents the climatological portion of the Parameterized Real-time Ionospheric Specification Model (PRISM), currently the operational model for specifying the current state of the ionospheric weather. The development of PRISM and PIM was funded by the Battlespace Environment Division within the Space Vehicles Directorate of the Air Force Research Laboratory (AFRL).

PIM consists of portable FORTRAN 77 source code and a large database of coefficients for an orthogonal function expansion. For user specified geophysical conditions and spatial coordinates, PIM produces electron density profiles (EDPs) between 90 and 25,000 km altitudes, corresponding critical frequencies and heights for the ionospheric E and F2 regions, and Total Electron Content (TEC).

The ionospheric portion of PIM is a parameterization of the results of several regional theoretical ionospheric models. This allows PIM to be computationally fast while retaining the physics of the theoretical ionospheric models. The parameterization compresses the output from the theoretical ionospheric models while preserving important characteristics such as density peaks and scale heights. The large base of data used by PIM contains coefficients from the parameterization. This constitutes PIM as described in Daniell et al., Radio Sci., 30, 1499-1510, 1995. In 1997 we incorporated the Gallagher plasmaspheric model (Gallagher et al., Adv. Space Res., 8(8), 15-24, 1988), a fast empirical model of plasmaspheric H+, into PIM.

Although the PIM FORTRAN code is fully portable to any system with a FORTRAN 77 compiler (with common extensions), the installation process is slightly different for Microsoft Windows and Unix systems, so there are two different downloadable versions of PIM. If you wish to learn more about PIM before downloading the code itself, you may obtain the PIM 1.7 User Guide separately.

Total electron content (TEC) on September 22 at 1:39 UT (Universal Time) for a solar activity index (F10.7) of 200. F10.7 is the solar radio flux at a wavelength of 10.7 cm (2800 MHz) in units of 10-22 W/m²/Hz as observed at Penticton, British Columbia, and adjusted to a distance of 1 Astronomical Unit (AU). The AU is the mean earth-sun distance. The TEC unit (TECu) is 1016 m^-2.

References
Daniell, R. E., Jr., L. D. Brown, D. N. Anderson, M. W. Fox, P. H. Doherty, D. T. Decker, J. J. Sojka, and R. W. Schunk (1995), Parameterized ionospheric model: A global ionospheric parameterization based on first principles models, Radio Sci., 30(5), 1499–1510, doi:10.1029/95RS01826

Gallagher, D. L., P. D. Craven, R. H. Comfort (1988), An empirical model of the earth's plasmasphere, Adv. Space Res., 8(8), 15-24, doi: 10.1016/0273-1177(88)90258-X.