Seasonal variations of magnesium atoms in the mesosphere-thermosphere

摘要

UV radiances from the Global Ozone Monitoring Experiment (GOME) spectrometer on the ERS-2 satellite are used to determine long-term dayside temporal variations of the total vertical column density below 795 km of the meteoric metal species Mg and Mg+ in the upper atmosphere. The GOME instrument has the ability to observe the ground state transition lines of Mg I at 285.2 nm and resolve the Mg II at 280 nm. A retrieval algorithm has been developed to determine column densities and applied to the years 1996-1997. Results show the middle latitude dayside Mg+ peaks in total vertical content during the summer, while neutral Mg demonstrates a much more subtle maximum in summer. Dayside trends are opposite previous midlatitude nighttime lidar observations, with the exception of calcium. The Mg+/Mg ratio has a seasonal variation, reaching a maximum in the summer. The total content of Mg+ is twice that of neutral Mg.