A rocket-launched parachute-deployed chemiluminescence sensor measured the verticl profile of nitric oxide from Poker Flat, Alaska, latitude 65.13 degrees North, in August 1984 and in January and Febuary 1985. All data refer to daylight periods shortly after local noon and cover altitudes from a lower limit of 27--53 km. Between 35 and 45 km the results indicate a large seasonal variation, with wintertime mixing ratios being roughly a factor of two above summer values. The winder profiles contained sharp positive vertical gradients that persisted through the highest altitudes observed, and near 50 km the mixing ratio from the February flight exceeded that seen in summer by a factor of four. Above the stratopause the mixing ratio observed in February increased dramatically and between 52 and 53 km rached 148.9 ppbv, an order of magnitude greater than typical-latitude values measured with this instrument. Such behavior is consistent with the absence of photodissociation in winter and a downward flux of odd nitrogen arising from a source located significantly higher than the stratopause, almost surely in the lower thermosphere. These results clearly support the existence of a vertical coupling between diverse regions of the atmosphere in the high latitude winter.