1990, 10(1): 50-60.
doi: 10.11728/cjss1990.01.050
Abstract:
The purpose of the paper is to give a brief introduction to the atmospheric and ionospheric models of MSIS-86 and IRI-86 and to deduce the thermospheric wind system, the spacial distribution and temporal variation of collision frequencies and ionospheric conductivities, which are important parameters in the research of thermosphere-ionosphere coupling. The model parameters used are different from that of the old models in many cases. For instance, the maximum temperature at 300km altitude is nearly to 80°Nfor winter solstice condition according the MSIS-86 model, while it appears at 23.5°Nin the Jacchia-77 model. Since a lot of new data from DE-Bsatellite flying across polar region are involved in the new model, the temperature distribution presented here is more reliable, especially at high latitudes.The main results from the model calculations given in this paper are the following:1. Generally, the thermospheric wind flows from daylit hemisphere to night side. The air flows longitudewards at noon-midnight meridian (northward at noon and southward at midnight) during the year of sunspot minimum, but is across the longitude at other meridians. At sunspot maximum, however, the wind blowing along a longitude line occurs at 2:00-14:00 LTmeridian, i.e. 30° degree of longitude from the location of maximum heating by solar radiation.2. Strong southward component of the wind velocity appears at high latitudes during magnetic disturbed days as a result of particle precipitation and Joule heating.3. On cursory examination, the conductivity distribution calculated from MISI-86 and IRI-86 is similar to that got by Maeda et al., nevertheless various important details are added. Therefore, recalculation of the conductivity for different special conditions (i.e. time, place, solar and geomagnetic activity etc.) is necessary for the further study of the thermosphere-ionosphere coupling.In brief, this work tries to set up a link between the model based on observations and the study based on theory. Since thte models only present the average situation, the application confined to the macroscopic research and analysis of the phenomena of large scale.
