On Atmospheric Pressure Oscillations Along the Pacific Coast of North America, 1873–1963

Abstract

Abstract An analysis is made of 90-year sea level atmospheric pressure records along the Pacific coast of North America and in adjacent regions. An investigation of the power spectra of monthly mean and extreme pressure fluctuations in the frequency range between 0 and 6 cycles per year showed that significant periodicities were associated only with the annual and semiannual pressure oscillations, and that there have been no secular changes. The amplitude of the annual pressure oscillation varies between 1 and 7 mb, that of the semiannual one between 1 and 3 mb. Large amplitude changes over short distances are observed when proceeding from a maritime to a desert environment. The extreme pressure range at individual stations varies from 33 mb in Hawaii to 94 mb in Alaska. The mean duration of positive and negative pressure anomalies (from long term monthly means) is of the order of 2 or 3 months; the extreme duration of these anomalies varies between 10 and 20 months. The probability functions for the extr...