GSM TIP Model Research Articles

Numerical modeling of ionospheric effects in the middle‐ and low‐latitude F region during geomagnetic storm sequence of 9–14 September 2005

This study presents the Global Self‐Consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) numerical simulations of the 9–14 September 2005 geomagnetic storm effects in the middle‐ and low‐latitude ionosphere. Recent modifications to the GSM TIP model include adding an empirical model of high‐energy electron precipitation and introducing a high‐resolution (1 min) calculation of region 2 field‐aligned currents and a cross‐cap potential difference. These modifications resulted in better representation of such effects as penetration of the magnetospheric convection electric field to lower latitudes and the overshielding. The model also includes simulation of solar flare effects. Comparison of model results with observational data at Millstone Hill (42.6°N, 71.5°W, USA), Arecibo (18.3°N, 66.8°W, Puerto Rico), Jicamarca (11.9°S, 76.9°W, Peru), Palmas (10.2°S, 48.2°W, Brazil), and San Jose Campos (23.2°S, 45.9°W, Brazil) shows good agreement of ionospheric disturbances caused by this storm sequence. In this paper we consider in detail the formation mechanism of the additional layers in an equatorial ionosphere during geomagnetic storms. During geomagnetic storms, the nonuniform in height zonal electric field is generated at the geomagnetic equator. This electric field forms the additional layers in the F region of equatorial ionosphere.

Sensitivity of GSM TIP model to the variability of the UV and EUV solar radiation

A self-consistent numerical global model of the coupled thermosphere, ionosphere and protonosphere (GSM TIP) has been used to examine the variations of the upper atmospheric parameters with respect to the changes of the solar extreme ultraviolet/ultraviolet (EUV/UV) flux from solar minimum to solar maximum conditions. Two model runs were executed for equinox and quiet geomagnetic periods for the same initial conditions. In the first case for the given UV flux the amplitude of the EUV flux was changed, whereas in the second case the UV flux was increased at a constant level of the EUV flux. For these cases only the global dynamical structure of the thermosphere has been studied. The model results have shown that in the first case the diurnal mode of the neutral wind increased at an altitude of 300 km and the semidiurnal mode increased at 120 km. In the second case the variation of the neutral wind circulation was opposite. Amplitudes of the variation were 15 m/s at 300 km and 5 m/s at 120 km.

Calculated and observed ionospheric parameters for a Magion 2 passage and EISCAT data on July 31, 1990

Ionospheric parameters, calculated by using a global numerically self‐consistent model of the thermosphere, ionosphere, and protonosphere (GSM TIP), are compared with experimental data. For July 31, 1990, there are ground‐based Common Programme 1 observations from the European Incoherent Scatter (EISCAT) radar station below about 600‐km height and simultaneous satellite data obtained onboard Magion 2 of the Active mission which passed near the EISCAT station around 1540 UT at an altitude of about 2500 km. The main goal of this paper is to estimate the ability of the first‐principles mathematical GSM TIP model to reproduce the real ionospheric situation in a wide altitude/latitude range. Numerical calculations were performed with the complete theoretical thermosphere‐ionosphere‐protonosphere model. The results presented show good agreement between the incoherent scatter radar measurements (Ne, Te, Ti, and ) and model calculations under certain model assumptions. Model runs were performed to study the influence of additional local and nonlocal heating sources, the role of vibrationally excited molecular nitrogen, and different convection patterns for the conditions under study. There is relatively good agreement between model results and experimental electron concentration data along the Magion 2 satellite orbit. It was found that the best fit results are achieved with an additional plasmaspheric heat source, while the importance of vibrationally excited molecular nitrogen has not yet been firmly established.