National Ecological Framework (18 of 23)

Canadian Ecodistrict Climate Normals 1961-1990 - Overview

Appendix 1

Andrew Bootsma, Research Branch, Agriculture and Agri-Food Canada, Ottawa


Michael Ballard, Polestar Geomatics Inc., Ottawa

Monthly climatic normals for the 1961-1990 normals period were compiled for the 1022 Ecodistricts in Canada. The climate normals information originated from point-based weather station data obtained from Environment Canada (1994). The average monthly and annual climate variables were estimated from monthly and annual climatic normals for each ecodistrict. In the source data, monthly normals were provided for each month plus an annual normal. Each of the 13 values were aggregated to the ecodistrict spatial framework independently. In some cases this results in the annual value for an ecodistrict not equaling the sum of the 12 monthly values. The annual values for an ecodistrict were not calculated as the sum of the 12 monthly values, but as an area weighted average of the annual values from source weather stations. Only data for Temperature, Precipitation and Growing Degree Days was provided for for the higher levels in the framework (ecozone, ecoprovince and ecoregion).

In a few cases where no representative climate stations were available, data for the Ecodistrict is indicated as missing (data field is filled with -999's). The amount of missing data varies with the variable and month, but 16 out of the 1022 Ecodistricts are affected (9, 98, 104, 105, 125, 267, 300, 858, 861, 872, 879, 907, 908, 912, 922 and 927).

Although each step of the development of the database was carefully validated, the authors cannot guarantee that there are no 'glitches' to be found in the data and would appreciate being informed of any data users come across where the procedures appear to have generated unreasonable results. Users of the data are cautioned that reliability of the interpolated data may be lower in areas of the country where climate stations are relatively sparse, e.g. in some regions of the north.


The Canadian Ecodistricts Climate Normals Database was developed by Andrew Bootsma, AAFC, Eastern Cereals and Oilseeds Research Centre, Ottawa and the GIS/data analysis work was done by Michael Ballard, Pole Star Geomatics Inc., Ottawa under contract to Agriculture and Agri-Food Canada, Research Branch and Environment Canada, Ecosystems Science Directorate.

The modified procedures for calculating EGDD were developed and tested by Andy Bootsma, AAFC, Eastern Cereals and Oilseeds Research Centre.

Dr. R. de Jong, AAFC, Eastern Cereals and Oilseeds Research Centre, assisted in formulating the procedures for calculating Penman PE and day length, and validating the Penman calculations.


Environment Canada. 1994. Canadian Monthly Climate Data and 1961-1990 Normals on CD-ROM. Environment Canada, Atmospheric Environment Service, Downsview, Ontario.


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Thornthwaite, C.W. and Mather, J.R. 1957. Instructions and tables for computing potential evapotranspiration and the water balance. Drexel Institute of Technology, Publications in Climatology Vol X, No. 3, Centerton, New Jersey. 311 pp.

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