AURORAL HEIGHTS OVER WEST-CENTRAL CANADA

Abstract

A complete analysis of the parallactic photographs of aurora taken at Chesterfield, N.W.T., (63.3°N., 90.7°W.) in 1933 show (a) a marked maximum in the heights of the lower limits of both homogeneous arcs and bands and auroral structures with rays between 100 and 110 km., (b) a mean height of the lower limit of arcs and bands of 108.2 km., (c) a mean height of the lower limit of auroral structures with rays of 113.4 km., (d) a decrease of height with increasing intensity, and (e) no definite evidence of a change of height with time after sunset. The results suggest that heights of aurora as observed from Northern Canada are slightly higher than of aurora observed from Norway. This may be due to the locations of the two regions relative to the zone of maximum auroral occurrence. No exceptionally low heights were observed at Chesterfield. Remeasurements of the 1933 photographs for Saskatoon (52.1°N., 106.6°W.) indicate that one arc was definitely below the 70-km. level, and possibly below the 60-km. level.