Climatology of polar mesospheric clouds. II - Further analysis of Solar Mesosphere Explorer data

An analysis was performed of data on nine summer seasons (1981-1985) collected by the SME satellite to study large-scale geographical and temporal variability of polar mesospheric clouds (PMC). It was found that the PMC season begins at high latitude, and, within 10 to 20 days, propagates to the lowest latitude where PMC exist; this occurs at about 20 to 40 days before summer solstice. It was also found that both PMC and mesopause temperatures reach their extrema about 20 days after solstice, supporting the ice particle hypothesis of PMC. There was no indication of any influence of the location of the auroral oval on the spatial distribution of PMC.