Optical Model of Atmospheric Aerosols in Russian Siberia for Correction of Satellite Data

Atmospheric components (aerosols and molecules) scatter and absorb solar radiation. They significantly influence the contrast and apparent resolution of satellite images of the Earth's surface taken in the visible and near infrared spectral channels. For accurate interpretation of satellite signals, remote sensing data have to be corrected for atmospheric effects. This requires knowledge of atmospheric spectral optical characteristics. Aerosol components of the atmosphere vary in space and time. Accordingly to recent investigations, there can be a significant error in interpretation of optical satellite images when the spectral behavior of aerosol optical depth used in atmospheric correction procedures does not correspond to reality. In this paper, an aerosol optical model that examines spectral optical depth and phase function for Siberia is presented. It is based on experimental measurements of the intensity of direct solar radiation, and on the microphysical parameters of aerosol s..

Validation of Odin/OSIRIS stratospheric NO₂ profiles

This paper presents the validation study of stratospheric NO2 profiles retrieved from Odin/OSIRIS measurements of limb-scattered sunlight (version 2.4). The Optical Spectrograph and Infrared Imager System (OSIRIS) NO2 data set is compared to coincident solar occultation measurements by the Halogen Occultation Experiment (HALOE), Stratospheric Aerosol and Gas Experiment (SAGE) II, SAGE III, and Polar Ozone and Aerosol Measurement (POAM) III during the 2002–2004 period. Comparisons with seven Systeme d'Analyse par Observation Zenithal (SAOZ) balloon measurements are also presented. All comparisons show good agreement, with differences, both random and systematic, of less than 20% between 25 km and 35 km. Inconsistencies with SAGE III below 25 km are found to be caused primarily by diurnal effects from varying NO2 concentrations along the SAGE III line-of-sight. On the basis of the differences, the OSIRIS random uncertainty is estimated to be 16% between 15 km and 25 km, 6% between 25 km and 35 km, and 9% between 35 km and 40 km. The estimated systematic uncertainty is about 22% between 15 and 25 km, 11–21% between 25 km and 35 km, and 11–31% between 35 km and 40 km. The uncertainties for AM (sunrise) profiles are generally largest and systematic deviations are found to be larger at equatorial latitudes. The results of this validation study show that the OSIRIS NO2 profiles are well behaved, with reasonable uncertainty estimates between 15 km and 40 km. This unique NO2 data set, with more than hemispheric coverage and high vertical resolution will be of particular interest for studies of nitrogen chemistry in the middle atmosphere, which is closely linked to ozone depletion