Recent developments on the homogenization of daily temperature in Canada

Long-term homogenized temperatures were prepared for the analysis of climate change in Canada. Non-climatic steps due to station relocation and changes in observing time were detected and adjusted in order to produce a more accurate assessment of climate trends. The homogenized temperatures have been used by many scientists working in the field of climate change studies.

A Second Generation of Homogenized Temperature is currently under development. It now includes 337 stations; more than 120 locations were added to the original datasets for a better spatial coverage. The series were also extended to cover the period 1900-2010 as much as possible by merging the observations of two or three nearby stations.

Recently, new procedures were developed to adjust daily temperatures for non-climatic variations. The redefinition of the climatological day in 1961 has generated a bias in the time series of the monthly and annual means of daily minimum temperatures. An approach based on hourly temperatures was applied to adjust the daily minimum temperatures. Newly developed techniques were considered as well for the detection of shifts in monthly mean temperature series due to station relocation. Different techniques for adjusting daily maximum and minimum temperatures were assessed using concurrent observations from nearby stations.

The presentation will discuss the challenges and difficulties encountered during the achievement of these tasks.