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Validation of satellite total ozone and NO2 data with ground-based SAOZ network

Florence Goutail(1,1)

(1) LATMOS/CNRS, Route de Verrieres, 91370 Verrieres le Buisson, France

Abstract

F. Goutail1, D. Ionov1,2, A. Pazmino1, J.-P. Pommereau1, F. Hendrick3, M. van Roozendael3, M. Pastel1, A. Griesfeller1

1 LATMOS (ex SA), CNRS, UVSQ, Verrières-le-Buisson, France 2 St. Petersburg State University, St. Petersburg, Russia 3 Belgian Institute for Space Aeronomy, Brussels, Belgium

SAOZ (Systeme d’Analyse par Observations Zenithales) is a ground-based UV-Visible zenith-sky spectrometer deployed between 1988 and 1995 at a number of NDACC stations at all latitudes on the globe. The instrument is providing ozone and NO2 total columns at sunrise and sunset using the Differential Optical Absorption Spectroscopy (DOAS) technique in the visible spectral range. SAOZ observations have been used extensively to validate various atmospheric chemistry satellite instru-ments such as nadir viewing TOMS, GOME, SCIAMACHY and OMI satellite spectrometers.

In the frame of the NDACC (Network for the Detection of Atmospheric Composition Change) UV-Visible working group, a tentative homogenization of ozone and NO2 processing of all UV-Vis zenith sky spectrometers has been initiated. The first recommendation is concerning the total ozone retrieval. A significant change for the SAOZ (Système d’Analyse par Observation Zénithale) network is the use of different cross-sections (O3, H2O, O4, and ring calculations) and a different spectral window fitting which leads to a recalculation of the slant columns. In addition it is recommended to use a climatological air mass factor (AMF) for O3 instead of an annual AMF usually used in standard SAOZ processing.

Here we present the results of comparisons between TOMS (since1988), GOME (since1995), SCIAMACHY (since2002), OMI (since2004) and ground-based SAOZ at all latitudes – tropics, mid-latitudes and polar regions - in both hemispheres. For ozone, the results show the impact of the NDACC recommendations on the differences between ground-based SAOZ and UV-Visible measurements from space.