Climate Estimates and Plant-Climate Relationships
New Algorithms Used For Some Derived Variables

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April 28, 2010 Update: The original algorithms for the following four derived variables:

  • fday — Julian date of the first freezing date of autumn
  • ffp — Length of the frost-free period (days)
  • sday — Julian date of the last freezing date of spring
  • gsdd5 — Degree-days >5 degrees C accumulating within the frost-free period


    • produced non-continuous predictions along a continuous gradient for mean monthly minimum temperature (mmin) and have been replaced. The poor behavior affected predictions where (1) winters are warm (January or December mmin greater than 2 C) and (2) where summers are cool (July or August mmin less than 5.5 C). The former was evident largely for predictions at low elevation at latitudes below 32 N and locations immediately along the Pacific Coast to latitudes of 50 N. The latter affected predictions at latitudes greater than 58 N and elevations over 2800 m in Mexico, over 2000 m in the Southwest and Great Basin of USA, over 1500 m in Northwest USA, and over 1000 m in western Canada. AsciiGrid maps of these variables have been deleted until they can be replaced with new calculations.

    The algorithms have been replaced with with non parametric regressions. The new algorithms will result in small differences in predictions even for areas not affected. Values from the following pages are being computed using the new algorithms:

  • Custom Climate Data Requests
  • Climate-FVS (Forest Vegetation Simulator) Ready Data