A real-time model-observation comparison of F₂ peak electron densities during the Upper Atmospheric Research Collaboratory campaign of October 1997

The first-principles, time-dependent Thermosphere-Ionosphere Nested Grid (TING) Model has been run automatically in real time to support the Upper Atmospheric Research Collaboratory (UARC) campaigns. This real-time modeling capability is the first published description of the running of a comprehensive model of the coupled thermosphere-ionosphere system that successfully performs real-time nowcasts and short-term forecasts of the upper atmosphere. These nowcasts and forecasts use observed real-time geophysical parameters as model input. Real-time modeling also provides an opportunity to evaluate rigorously the accuracy of the model for space weather purposes by comparing model outputs with observations. Digisonde-derived F₂ peak electron densities from three sites (Millstone Hill, Tromsø, and Sondre Stromfjord) were compared with the corresponding TING model outputs during the October 14-29, 1997, UARC campaign. It is found that under solar minimum, equinox, geomagnetically quiet conditions, the F₂ peak electron densities simulated by the model were in good agreement with those observed by the Digisondes. At both midlatitudes and high latitudes the TING Model almost reproduced the observed diurnal variations of F₂ peak electron densities. There were, however, short-period variations of F₂ peak electron densities during both day and night that were not simulated by the model.