Spectral analysis of extinguished sunlight

✍ Scribed by Frédéric Zagury; Florence Goutail

• Book ID: 104426483
• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 283 KB
• Volume: 8
• Category: Article
• ISSN: 1384-1076
• DOI: 10.1016/s1384-1076(03)00047-2

✦ Synopsis

ŚAOZ (Systeme d'Analyse par Observation Zenitale) is a balloon-borne experiment which determines the column density of several molecular species from the visible spectrum of sunlight. We will use sequence of spectra collected during a sunset to discuss atmospheric extinction, and the nature of the radiation field in the atmosphere. The radiation field in the atmosphere is, from daylight to sunset, and with a clear sky, dominated by light coming from the direction of the sun. This light is composed of direct sunlight (extinguished by the gas), and of sunlight forward-scattered by aerosols. As the sun sets, aerosol scattering is first perceived towards the UV. It progressively replaces direct sunlight over all of the spectrum. Our analysis permits fixing the main parameters of each component of the radiation field at any time. The fits we find for the extinction of sunlight in the atmosphere must also apply to starlight. Thus, the present work can be used in astronomy to correct ground-based spectral observations for extinction in the atmosphere.