Polar thermosphere-stratosphere photochemical coupling experiment: Two rocket measurements in polar winter at 69°N

Abstract

Two rocket experiments were carried out just before and after the polar night at Andoya (69°N), Norway to investigate transport of nitric oxide produced by auroral processes into the middle atmosphere and its influence on the ozone chemistry. Nitric oxide densities of (2-5) × 10⁸ cm^-3 found in the 70-90 km region are one to two orders of magnitude larger than those at middle latitudes. The measured density profiles appear to agree semiquantitatively with model simulations which includes auroral processes. The influence on ozone densities in the 70-90 km region due to such enhanced nitric oxide abundance is found to be still insignificant as compared to that due to transport in the middle of February, one month after the end of polar night and one month before the spring equinox. The larger ozone densities found in February (in spite of longer sunlit duration) than in November in the 40-60 km region again support predominance of transport over photochemical destruction.