Analysis and Interpretation of Long-Term Climatic Variability Along the West Coast of North America

  1. David H. Peterson
  1. Gunnar I. Roden

Published Online: 23 MAR 2013

DOI: 10.1029/GM055p0093

Aspects of Climate Variability in the Pacific and the Western Americas

Aspects of Climate Variability in the Pacific and the Western Americas

How to Cite

Roden, G. I. (1989) Analysis and Interpretation of Long-Term Climatic Variability Along the West Coast of North America, in Aspects of Climate Variability in the Pacific and the Western Americas (ed D. H. Peterson), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM055p0093

Author Information

  1. School of Oceanography, Wb-10, University Of Washingtonseattle, Wa

Publication History

  1. Published Online: 23 MAR 2013
  2. Published Print: 1 JAN 1989

ISBN Information

Print ISBN: 9780875900728

Online ISBN: 9781118664285

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Keywords:

  • Climatic changes—Pacific Area.;
  • Paleoclimatology—Pacific Area.;
  • Climatic changes—West (U.S.);
  • Paleoclimatology—West (U.S.);
  • Atmospheric carbon dioxide.

Summary

Aspects of climatic variability along the west coast of North America are investigated on the basis of instrumental oceanic and meteoro-logical records taken since 1827. The records indicate both year-to-year and decadal scale fluctuations. By applying modern statistical techniques the fluctuations are described in terms of spectral composition, durations, extreme values, trends, and coherences. In the low frequency range between O and 6 cycles per year the only statistically significant peaks occur at the annual and semiannual frequencies; the amplitudes of these peaks have not changed significantly during the past century. Mean durations of nonseasonal temperature fluctuations above and below the zero level vary between 2 and 4 months. Extreme durations of nonseasonal temperature variations vary between 10 and 20 months. Significant positive trends of air temperature and sea level are found at big city locations, but not at nearby rural locations, suggesting that some of the trends are affected by manmade activities. The areal coherence of fluctuations for a given variable and the coherence among the fluctuations of different variables depends on the dynamics of the ocean-atmosphere system. For sea and air temperatures and for atmospheric pressure and sea level, good coherence is found over distances of the order of the dimension of planetary weather disturbances. Fluctuations between sea and air temperature and between sea level and atmospheric pressure are strongly correlated at well exposed coastal stations.

Examples are given of noteworthy climatic events during the last century and a half, such as the unusual winter of 1862 (extreme cold in the Pacific Northwest, extreme floods in California), the warm winters of 1926, 1931, 1941, 1958 and 1983 (El Niño related), and the cold winters of 1937, 1950, 1957 and 1969 (related to polar type atmospheric disturbances). The records indicate also extended cold periods during 1857–1863 and 1948–1956, and warm periods during 1864–1870, 1940–1945, and 1977–1984; the cause for these long-term scale fluctuations is not known.