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Ann. Geophys., 21, 797-804, 2003
www.ann-geophys.net/21/797/2003/
© European Geosciences Union 2003
A new regularized inversion method for the retrieval of stratospheric aerosol size distributions applied to 16 years of SAGE II data (1984–2000): method, results and validation
C. Bingen, F. Vanhellemont, and D. Fussen
Belgian Institute for Space Aeronomy, Brussels, Belgium
Abstract. We apply a regularization
method for the optical inversion of SAGE II aerosol extinction profiles and
derive the particle number density N, the mode radius r
and width s of an effective lognormal aerosol size
distribution. The constraint applied to the inversion scheme allows us to
appreciably enhance the stability of the solution. Therefore, because of the
disposal of a more stable inversion scheme and of the wide extend of SAGE II
data in time and space, we were able to improve the estimation of the aerosol
parameter profiles with respect to previous published retrievals and, hence,
our knowledge of the aerosol distribution characteristics in space and time.
After presenting the inversion method and retrieved profiles concerning the
particle number density profile over the time period 1984–2000, we validate
our results by means of data derived from both in situ and remote spectral
measurements. We also discuss the limits of the comparison between the various
types of measurements due to their respective particularities. The validation
gives a satisfying agreement with other data sources for N and r
as long as the mode radius is not too small compared to the shortest SAGE II
wavelength, whereas s appears to be less easily
retrieved with a good accuracy.
Key words. Atmospheric composition
and structure (aerosols and particles; middle atmosphere – composition and
chemistry; volcanic effects)
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