50 r 



45- 



40 



25 



20 L 



J L 



145 140 135 130 125 120 



LONGITUDE, DEGREES W 



CANA DA 

 USA 



J L 



□ o 



1-10 

 11-20 



15 110 



^ 100 



20 



S 



\r^ 



A L 



JAN APRIL JULY OCT 

 1950 1950 



TIME OF YEAR 



Figure S- Time space distribution of data used ! 



trface temperature comparisons 



46 



