A semi‐empirical low‐latitude ionospheric model

Since current empirical models specifying low-latitude electron density profiles severely underestimate the daytime plasma density scale-height and total electron content (TEC) values, a semi-empirical low-latitude ionospheric model (SLIM) has been developed which is not only computationally fast, but also more realistic. Electron density profiles (180–1800 km) are theoretically calculated as a function of latitude (every 2° between 24°N and 24°S dip latitude) and local time (every half hour, over 24 hours LT) by solving the time-dependent plasma continuity equation. Using simple exponential functions, sets of coefficients are then generated which reproduce these individual profiles. The coefficients themselves are easily stored, quickly retrieved and form the basis for a fast, portable, semi-empirical computer code. This paper describes briefly the input parameters used to theoretically calculate the profiles and the procedures used to generate the coefficients. The SLIM profiles are compared with the Chiu and Bent empirical models for equinox, solar maximum conditions, while calculated 6300 A airglow intensities and TEC values are compared with available observations. The SLIM profiles, their coefficients, TEC and 6300 A airglow intensities are available in tabular and computer formats.

[1]  P. Hays,et al.  Volume emission rate profiles of the 6300‐Å tropical nightglow obtained from the AE‐E satellite: Latitudinal and seasonal variations , 1982 .

[2]  Ronald F. Woodman,et al.  F region east‐west drifts at Jicamarca , 1981 .

[3]  J. Klobuchar,et al.  Modeling the total electron content observations above Ascension Island , 1983 .

[4]  D. Anderson.  Modeling the ambient, low latitude F-region ionosphere—a review , 1981 .

[5]  P. Kendall,et al.  Magnetoplasma diffusion at F2-region altitudes , 1967 .

[6]  Marsha R. Torr,et al.  The role of metastable species in the thermosphere , 1982 .

[7]  Y. Chiu.  An improved phenomenological model of ionospheric density , 1975 .

[8]  D. Anderson,et al.  Semi-empirical low-latitude ionospheric model. Environmental research papers , 1985 .

[9]  Jeffrey M. Forbes,et al.  Atmospheric tides: 1. Model description and results for the solar diurnal component , 1982 .

[10]  A. Hedin,et al.  A revised thermospheric model based on mass spectrometer and incoherent scatter data - MSIS-83 , 1983 .

[11]  M. Torr,et al.  Chemistry of the thermosphere and ionosphere , 1979 .

[12]  Jeffrey M. Forbes,et al.  Atmospheric tide: 2. The solar and lunar semidiurnal components , 1982 .

[13]  R. J. Moffett,et al.  lonization transport effects in the equatorial F region , 1966 .

[14]  L. McNamara.  Prediction of total electron content using the International Reference Ionosphere , 1984 .

[15]  K. Davies,et al.  ATS‐6 satellite radio beacon measurements at Ootacamund, India , 1979 .

[16]  Ronald F. Woodman,et al.  Vertical drift velocities and east‐west electric fields at the magnetic equator , 1970 .

[17]  R. Dickinson,et al.  Seasonal and solar cycle variations of the zonal mean circulation in the thermosphere , 1977 .

[18]  D. Anderson,et al.  A theoretical study of the ionospheric F region equatorial anomaly—II. results in the American and Asian sectors , 1973 .

[19]  Ronald F. Woodman,et al.  Dependence of equatorial F region vertical drifts on season and solar cycle , 1979 .

[20]  R. J. Moffett,et al.  The Equatorial Anomaly in the Electron Distribution of the Terrestrial F-Region , 1979 .