POLAR THERMOSPHERE-STRATOSPHERE PHOTOCHEMICAL COUPLING EXPERIMENT - 2ROCKET MEASUREMENTS IN POLAR WINTER AT 69-DEGREES-N

Two rocket experiments were carried out just before and after the pola r night at Andoya (69 degrees N), Norway to investigate transport of n itric oxide produced by auroral processes into the middle atmosphere a nd its influence on the ozone chemistry. Nitric oxide densities of (2- 5) x 10(8) cm(-3) found in the 70-90 km region are one to two orders o f magnitude larger than those at middle latitudes, The measured densit y profiles appear to agree semiquantitatively with model simulations w hich includes auroral processes. The influence on ozone densities in t he 70-90 km region due to such enhanced nitric oxide abundance is foun d to be still insignificant as compared to that due to transport in th e middle of February, one month after the end of polar night and one m onth before the spring equinox. The larger ozone densities found in Fe bruary (in spite of longer sunlit duration) than in November in the 40 -60 km region again support predominance of transport over photochemic al destruction.