REMOTE SENSING OF STRATOSPHERIC AND UPPER TROPOSPHERIC AEROSOLS BY MEANS OF GROUND-BASED TWILIGHT SKY SPECTRAL PHOTOMETRY

摘要

The presence of aerosol in the stratosphere – upper troposphere essentially disturbs twilight sky brightness, especially in red – near infrared wavelengths. In this wavelength domain, the stratospheric aerosol layer causes a prominent “hump” on a curve of the twilight sky spectral brightness as a function of the solar zenith angle. Stratospheric and upper tropospheric aerosol extinction profiles over Caucasus region were retrieved at the measurement wavelength 780 nm. The twilight sky brightnesses were modeled in spherical atmosphere approximation using Monte-Carlo technique to represent correctly multiple scattering. The retrieved stratospheric aerosol was in a background condition from October 2009 to June 2011 with the optical depth varying in the range 0.01 - 0.02. A sharp increase (up to 0.08-0.1) in July-August 2011 was observed after the Nabro eruption (June 2011, Eritrea).