Tidal Frequencies in the Time Series Measurements of Atmospheric Muon   Flux from Cosmic Rays
  Tidal frequencies are detected in time series muon flux measurements performed over a period of eight years. Meson production and subsequent decay produce the muons that are observed at ground level. We interpret the periodic behavior as a consequence of high altitude density variations at the point of meson production. These variations are driven by solar thermal cycles. The detected frequencies are in good agreement with published tidal frequencies and suggest that muons can be a complementary probe to the study of atmospheric tides at altitudes between 20 to 60 km. 
H. Takai, C. Feldman, M. Minelli, J. Sundermier, G. Winters, M. K.   Russ, J. Dodaro, A. Varshney, C. J. McIlwaine, T. Tomas...
astro-ph.HE astro-ph.IM