Retrieval of stratospheric aerosol size information from OSIRIS limb scattered sunlight spectra

摘要

Recent work has shown that the retrieval of stratospheric aerosolvertical profiles is possible using limb scattered sunlightmeasurements at optical wavelengths. The aerosol number densityprofile is retrieved for an assumed particle size distribution andcomposition. This result can be used to derive the extinction atthe measured wavelength. However, large systematic error can resultfrom the uncertainty in the assumed size distribution when theresult is used to estimate the extinction at other wavelengths. Itis shown in this work that the addition of information obtained fromthe near infrared limb radiance profile at 1530 nm measured by theimaging module of the OSIRIS instrument yields an indication of theaerosol size distribution profile that can be used to improve thefidelity of the retrievals. A comparison of the estimatedextinction profile at 1020 nm with two coincident occultationmeasurements demonstrates agreement to within approximately 15%from 12 to 27 km altitude.