Changes in agriculture related indices based on adjusted / homogenized daily temperature and precipitation observations in Canada

The recently updated homogenized daily surface minimum and maximum temperatures and adjusted daily rainfall and snowfall observations are used to address changes in a few indices related to agriculture.

The second generation homogenized temperature dataset contains 337 stations. New procedures have been recently developed to address the changes in observing time at airport stations in 1961 and new adjustments have been applied as result of homogeneity testing. The second generation adjusted precipitation datasets consist of the best quality rainfall and snowfall manual observations for over 460 locations across Canada. Adjustments were applied for all known issues related to daily rain gauge and snow ruler observations. Adjustments needed for merging station observations to produce longer time series were obtained either from overlapping periods or standardized ratio homogeneity tests using surrounding stations.

Trends are examined for several agricultural indices including growing season, growing degree-days, frost-free period, seasonal percent of long-term average precipitation, number of days with precipitation and standardized precipitation index. Seasonal maximum 1-day precipitation and consecutive 10-day precipitation are used to represent extreme precipitation conditions. The trends in indices will be presented for the periods 1900-2010 and 1950-2010, along with examples at specific locations in agricultural sectors.