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ESA
     
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A new global climatology of different types of aerosols in the stratosphere by GOMOS-Envisat data treated with the LPC2E processor

Veronica Salazar(1) and Jean Baptiste Renard(1)

(1) CNRS, 3A Avenue de la Recherche Scientifique, 45071, France

Abstract

The Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument onboard the satellite ENVISAT, in orbit since March 2002, is an UV-Visible-Near IR spectrometer which works in occultation mode measuring the transmission of light from stars that are setting below the Earth´s horizon. Only the products from night observations are treated here for stars of all magnitudes, and a data selection on each individual profile is made concerning standard deviation of the aerosol extinction. We present the study of the wavelength dependence over the 2002-2006 period for stratospheric aerosols using both, the official ESA algorithm and the one developed at LPC2E, in the 400-675 nm spectral range, from the tropopause up to an altitude of around 70 km. The LPC2E processor is an improved algorithm derived from those commonly used for balloon instruments that allows us to retrieve more accurately the dependence of aerosol extinction because of minimizing the effect of chromatic scintillation and because of remote sensing measurements in the UV-Visible. The values of aerosol extinction at 500 nm, as well as the “color index”, magnitude which varies with spectral dependence, and the wavelength of the maximum extinction at each altitude have been used to establish a global climatology of aerosol content by latitude ranges. By these results we propose a vertical distribution of different types of aerosols in the stratosphere, allowing us to conclude unambiguously about the presence of solid particles above 30 km at all latitudes. The presence of soot and interplanetary material is discussed, as well as their spatial variability and the transport of solid aerosols related to specific events. The layer of liquid aerosols can be observed in the lower stratosphere where the value of extinction is greater in blue, as it is typical for small droplets.

 

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