Global column density retrievals of mesospheric and thermospheric Mg I and Mg II from SCIAMACHY limb and nadir radiance data

• Published in: Journal of Geophysical Research: Atmospheres 2008-07, Vol.113 (D13), p.n/a
• Main Authors: Scharringhausen, Marco, Aikin, Arthur C., Burrows, John P., Sinnhuber, Miriam
• Format: Article
• Language: English
• Subjects: airglow; Algorithms; Atmospheres; Density; Earth sciences; Earth, ocean, space; Exact sciences and technology; Limbs; Magnesium; Mesosphere; Radiance; Thermosphere
• ISSN: 0148-0227; 2169-897X; 2156-2202; 2169-8996
• DOI: 10.1029/2007JD009043

The Scanning Imaging Absorption Spectrometer for Atmospheric Chartography instrument (SCIAMACHY) instrument exhibits useful observational abilities to separate meteoric metal total content within different levels of the atmosphere. In this work, we present an algorithm to give the total content and to separate the total column into two partial columns in the thermosphere and the mesosphere, using measurements of resonant radiation by the SCIAMACHY instrument. Limb and nadir measurements are used. The results presented here constitute the first simultaneous measurements of mesospheric and thermospheric column densities including the successful separation of same. We present column density measurements of Mg II and Mg I in the mesosphere and the thermosphere and the total content. The data set considered here covers the latitude range from 80°S to 80°N and covers the time range from 2002 to 2006. Measurements are taken on a global scale to investigate seasonal and spatial variations. Total columns range from 107 to 1010 cm−2, in good agreement with previous satellite measurements and model calculations. The temporal evolution of both Mg I species is investigated over the time range from mid‐2002 until the end of 2006. A pronounced minimum in 2003 and a subsequent increase until 2006 are observed for the ionized species. The global distribution of both Mg I and Mg II is found to be seasonally varying, exhibiting maximum column densities within the summer hemisphere. No significant correlation with the solar activity is found. Increased abundances of Mg II are observed within regions of high geomagnetic activity (i.e., the northern and southern auroral ovals) only if the background abundance of Mg II is low. It is concluded that the increase of Mg II due to particle impact is a minor effect.