The dynamics of auroral absorption parameters in the 22nd solar activity cycle

Examination of auroral absorption (AA) occurrence rate and AA meridional distribution versus local time and in the course of the solar cycle has been performed by riometer observations from 1985 to 1995 at the longitude of Yakutsk. Geomagnetic latitude of the region of absorption maximum occurrence changes in the course of the solar cycle from 66.5° to 64.4°. The largest displacement of this region to lower latitudes is observed during years of maximum solar activity. The half-width of the region is ~8° at solar minimum and ~10° at solar maximum. It has been also revealed that the region of AA is shifted to higher latitudes at daytime (1000-1400LT), and to lower ones in the evening (1800-2000LT), the displacement from the daily average position being ~1° and ~3° in the years of solar activity maximum and minimum, respectively. In all years at 2000-2100LT a short-term extension of the AA region by 1-4° is observed. The interpretation of the observationa is proposed.