Multivariate Time Series Analysis of Forty Years of Multidirectional Muon Observations

• Activity Number: 24
• Type: Topic Contributed
• Date/Time: Sunday, August 3, 2014 : 2:00 PM to 3:50 PM
• Sponsor: Section on Physical and Engineering Sciences
• Author(s): Charlotte Haley*+ and David J. Thomson
• Companies: Queen's University and Queen's University
• Keywords: Spectrum Analysis ; Time Series ; Multivariate Statistics ; Cosmic Rays ; Muon Monitoring

Abstract

Multidirectional surface and underground (Sakashita) muon telescopes at Nagoya, Japan have been measuring secondary cosmic ray intensity since 1970 and 1977, respectively. These multidirectional time series are used to study cosmic ray anisotropy for modeling and forecasting of geomagnetic storms. Previous studies have shown 27-day periods (corresponding to solar Carrington rotations) in data in 1982-1984 following Forbush decrease events from muon data collected on the surface as well as underground. In the frequency domain, multivariate spectral analysis can be used to determine the contribution of these solar frequencies to signal power, as well as phase and angle of incidence. In this study, spectral matrices are decomposed using the singular value decomposition, and the resulting singular values are investigated for solar signatures and other artifacts.