Observations of the variations of thermospheric winds in Northern Scandinavia between 1980 and 1986: A study of geomagnetic activity effects during the last solar cycle

Abstract

Since late 1980, a ground-based Fabry-Perot interferometer has been in operation near Kiruna, Sweden (20.4° E, 67.8° N). This instrument has recorded upper thermospheric neutral winds under a wide range of geophysical conditions which have occurred during six observing winters. These data cover the period from the time of maximum geomagnetic activity during the last solar cycle, 1980/82, to the 1985/86 period of generally quiet geomagnetic activity near sunspot minimum. A statistical analysis of the data from about 400 nights of observation provides a graphic description of the generally rapid time-dependence of upper thermospheric winds in the vicinity of the mean auroral oval to individual geomagnetic disturbances. The data also provide an excellent data base describing the auroral oval. The data describe ion convection patterns as they respond to variable geomagnetic activity, and also the mean distribution of OI 630 nm emission as a function of local time, latitude and geomagnetic activity. These results can be used to examine the geomagnetic input parameters to a global thermospheric model (for example the semi-empirical global models of magnetospheric convection) as required to bring the simulations of thermospheric circulation into overall improved agreement with the observations.