A thermosphere-ionosphere nested grid (TING) model.
Wenbin Wang · Deep Blue (University of Michigan) · 1998
A three-dimensional, time dependent, nested grid model has been developed to study mesoscale processes in the coupled thermosphere-ionosphere system. This new Thermosphere-Ionosphere Nested Grid (TING) Model, which builds up on the existing and well proven NCAR-TIGCM, calculates simultaneously global (coarse resolution) and local (high resolution) distributions of the neutral and plasma winds, temperatures, and composition. It is comprised of two coupled codes--a global coarse grid (TIGCM) and a local nested grid that uses the same solvers as the coarse grid, but has higher spatial and temporal resolution. The size, location and level of nesting of the high resolution grid is adjustable to suit the specific application. Large scale, long term variations simulated by the coarse grid can propagate into the interior of the nested grid through a one-way interaction scheme and influence the calculations there. The TING Model has been used to study the ionospheric mid-latitude electron density trough. It is found that mid-latitude troughs have significant solar cycle, seasonal, UT, geomagnetic activity and IMF B$\sb{\rm y}$ component variations. Auroral images from satellite observations have also been used to specify the time varying geometry and structures of the auroral oval. It is found that the TING Model nested grid can reproduce almost all the fine structures seen in the images, while the coarse grid tends to smear out these fine structures. Compared to results obtained by using the auroral statistical models that are usually applied, the TING Model also predicts quite different structures and values of E-region electron densities and Joule heating when auroral images are used. A diagnostic package has been developed to perform post processing of the TING Model outputs to investigate important processes that are responsible for the simulated perturbations in neutral and plasma fields. This term by term analysis tool is applied to study the momentum forcings at high latitudes and the mid-latitude post sunrise F-region electron temperature enhancement. An automatic procedure has also been designed for the TING Model to perform real-time modeling for UARC campaigns. Comparisons of the model outputs with incoherent scatter radar and digisonde observations are made in these campaigns. It is found that TING Model predictions of the F$\sb2$ peak electron densities are in good agreement with those observed by digisondes at both mid- and high latitudes.