Department of Earth Sciences. Iowa State University, Ames 5001
The finite Fourier transform method of cross-spectral analysis is used to investigate the relationship between the Zurich annual sunspot number and state monthly mean temperature and precipitation derived from the Climatological Observation Network data for most of the continuous United States. Both the single (11 year) and the double (21 year) sunspot cycles are investigated. Our analyses show statistically significant relationships between the double sunspot cycle and the “January thaw” phenomenon along the East Coast and between the double sunspot cycle and “drought” (June temperature and precipitation) in the Midwest.