Short-Period Kinetic Energy Cycles in the Atmosphere

Short-period cycles in the large-scale atmospheric circulation were investigated with time series of kinetic energy, its generation and outflow, which were computed twice a day for a 5-year period over the North American Continent. The spectra were computed from the autocorrelation curves, and were compared with the red noise spectra to evaluate the statistical significance of the energy cycles. The maxima of time spectra of different energy parameters show frequent agreement. The commonly reported kinetic energy cycles with periods of one to two weeks are observed; however, they are not statistically significant and also show very high year-to-year irregularity. Significant cycles with periods around 40 days and 2–4 days are also noted.