Indirect phase height measurements of low frequency radio waves from 1959 to 2009 are analyzed in order to examine the long-term variability of the mesosphere (D layer, about 82 km altitude) above Europe. The concept of standard phase heights (SPH) guaranties the continuity of the series even in the case of slight frequency changes. Over 50 years field strength measurements of the broadcasting station Allouis (Central France) have been maintained at Kühlungsborn (54° N, 12° E, Mecklenburg, Northern Germany). A homogenized daily series was generated with coverage of 98 % of time for SPH and for plasma scale heights (PSH). Both are used to derive the thickness temperature change between stratopause and 82 km altitude, and in addition the temperature change at 82 km is estimated by the use PSH series alone. Due to enhanced downward transport of NO and subsequent photo-ionization the winter anomaly for SPH and PSH was found. The SPH-series are partially anti-correlated to the solar cycle because stronger photo-ionization is linked with higher number of electrons, which reduces the SPH. Further the statistical analysis of the SPH-series shows a significant overall trend with a decrease of 114 m per decade induced by a shrinking stratosphere due to global warming and mesospheric processes, but with strong intra-decadal variability in winter. Furthermore the PSH-series embraces no significant overall trend but a strong coherence with the 22 year-Hale cycle of the sun. The indicated temperature trends are discussed.