Luni‐solar 18.6‐ and 10—11‐year solar cycle signals in H. H. lamb's dust veil index

Abstract

AbstractMaximum entropy and Yule‐Walker methods of spectrum analysis applied to Lamb's dust veil indices (dvi) for the Northern Hemisphere (1500–1968) show two strong peaks, with periods of 18.6±0.5 and 10.8±0.3 years. They are identified as the 18.6‐year luni‐solar Mn and 10–11‐year solar cycle Sc signals, which have recently been reported in a wide variety of climate and economic time series. The signals were transformed into the time domain by band‐pass filters, their wavetrains summed, and the sum superimposed on trend‐like components of the dvi; it is found that they account for 48 per cent of variance in the index.