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Synoptic Scale Atmospheric Circulation and Summer Drought Variability of the Past Three Centuries, Boreal Canada

  • Author(s) / Creator(s)
  • Five independent multicentury reconstructions of the July Canadian Drought Code and one reconstruction of the mean July-August temperature were developed using a network of 120 well-replicated tree-ring chronologies covering the area of the eastern Boreal Plains to the eastern Boreal Shield of Canada. The reconstructions were performed using 54 time-varying reconstruction submodels that explained up to 50% of the regional drought variance during the period of 1919-84. Spatial correlation fields on the six reconstructions revealed that the meridional component of the climate system from central to eastern Canada increased since the mid-nineteenth century. The most obvious change was observed in the decadal scale of variability. Using 500-hPa geopotential height and wind composites, this zonal to meridional transition was interpreted as a response to an amplification of long waves flowing over the eastern North Pacific into boreal Canada, from approximately 1851 to 1940. Composites with NOAA Extended Reconstructed SSTs indicated a coupling between the meridional component and tropical and North Pacific SST for a period covering at least the past 150 yr, supporting previous findings of a summertime global ocean-atmosphere-land surface coupling. This change in the global atmospheric circulation could be a key element toward understanding the observed temporal changes in the Canadian boreal forest fire regimes over the past 150 yr.

  • Date created
    2006
  • Subjects / Keywords
  • Type of Item
    Article (Published)
  • DOI
    https://doi.org/10.7939/R3TM7215V
  • License
    © 2006 American Meteorological Society. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.
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  • Citation for previous publication
    • Girardin, M-P., Tardif, J.C.,Flannigan, M.D. and Bergeron, Y. (2006). Synoptic Scale Atmospheric Circulation and Summer Drought Variability of the Past Three Centuries, Boreal Canada. Journal of Climate, 19, 1922-1947. DOI: 10.1175/JCLI3716.1.