THE SPECTRUM OF DAILY TEMPERATURES AS A CLIMATIC INDICATOR

Abstract

After removal of the annual variation, daily temperatures at 17 North American stations were subjected to spectrum analysis. Winter spectra at west coast maritime stations were characterized by energy mostly at periods of the order of 2 weeks, whereas at east coast stations, most of the variance was produced with periods of the order of a week, with intermediate spectra in the center of the continent. In summer, the spectra were flatter and maxima less distinct; still, the shorter periods predominated at the northeast coast. From the spectra, a ?rhythm? index was defined which quantitatively characterizes the rhythm of the temperature variation in the various regions of North America. The variance of temperature deviations from normal was also computed and appears to be an index of continentality.