Growing Degree Days (GDD)

Interpolated GDD contours

This map shows GDD contours which have been interpolated using a distance weighted method from the valid stations, which are indicated by grey crosses.

GDD layer generated from a linear regression

This layer is a growing degree day layer which has been generated by doing a linear regression on the following variables:

UTM easting
UTM northing
elevation
slope
aspect
proximity to Lake Ontario
proximity to Lake Erie

with growing degree days as the dependent variable.

The regression formula looks like this:
gdd_regressed=(0.192834441*niagara_250.dem)+(2.651092866*lake_ontario.proximity)+ (27.81441585*niagara_250.slope)+(-0.635415489*niagara_250.aspect)+ (-0.093517573*lake_erie.proximity)+(0.004503886*(579648.35152722+ (cols*58.43425725)))+(0.017223864*(4736857.55262194+((864-rows)*78.79681987))) -82834.37401

The results of this regression:

I think this regression works quite well because when the contours from the interpolated layer are overlayed on the regression, the similarity between the two layers can be seen.