A number of indicators of climatic trends in the Queen Charlotte Islands are examined in this report. The purpose of the analysis is to determine extent of climatic influence on recent increases in the incidence of slope failures and stream channel enlargement. Winter (October to April) total rainfall, precipitation, and snowfall; winter mean temperature; water-year (October to September) total stream run off; and the exceedance of daily precipitation amounts were studied using a variety of trend and data homogeneity analysis techniques.
Although there was considerable lack of homogeneity foundin the various long-term data sets available from the Queen Charlotte Islands, and a low regional coherence between the data sets, several consistent climatic fluctuations were evident. The most notable are the periods of generally above-average winter rainfall and temperatures, 1923 to 1946, 1957 to 1964, and 1974 to 1984, with intervening periods of generally below-average winter rainfall and temperature, from 1946 to 1957 and 1964 to 1974. The most recent of these fluctuations (since 1946) appear to correspond with general changes in synoptic-scale circulation patterns across the northeastern Pacific Ocean area. The period since 1974, particularly significant to the Fish/Forestry Interaction Program, includes 7 years of exceptionally high precipitation in at least some portion of the Queen Charlotte Islands.
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Updated December 16, 2008