Solar cycle and long-period variations of mesospheric temperatures

Evidence for a temperature variation above about 55 km between years of high and low solar activity is found in rocket data of Volgograd (49 degrees N, 44 degrees E) 1969-83, reaching a solar-cycle amplitude of 6K, whereas below 55 km no statistically significant cycle effect is detected. This mesospheric temperature variation is in qualitative agreement with a pressure variation at 80 km derived from lower ionosphere radio reflection heights near 51 degrees N, 13 degrees E, measured at Kuhlunsborn/GDR, covering almost two solar cycles. When the solar cycle variation is removed from these 80 km pressure data by means of a regression analysis, there remains a quasi-cycle of about 20 yr, which agrees well with observations of a general cooling of the northern mid-latitude stratosphere between 1965 and 1977, reported by other authors.