Forty years of noctilucent cloud observations near Moscow: Database and simple statistics

The observation procedure and relevant database of Moscow (56°N, 37°E) noctilucent cloud (NLC) systematic observations (1962-2001) are described. The long-term series of Moscow NLC data are analyzed and compared to the observations in western Europe. Statistical analysis of seasonally averaged parameters of the NLCs is carried out. Characteristic periods in interannual variability of the integral NLC brightness fluctuation are extracted. Particular attention is paid to decadal (∼10 years) periodicity in the NLC occurrence and their brightness. A distinct difference between decadal periodicity in NLC parameters and solar activity is found and its possible origin is discussed.