Tropospheric ozone from IASI: comparison of different inversion algorithms and validation with ozone sondes in the northern middle latitudes

C. Keim (1) , M. Eremenko (1) , J. Orphal (1) , G. Dufour (1) , J.-M. Flaud (1) , M. Höpfner (2) , Anne Boynard (3) , Cathy Clerbaux (3) , Sébastien Payan (4) , Pierre-François Coheur (5) , Daniel Hurtmans (5) , H. Claude (6) , H. Dier (7) , B. Johnson (8) , H. Kelder (9) , R. Kivi (10) , T. Koide (11) , M. López Bartolomé (12) , K. Lambkin (13) , D. Moore (14) , F. J. Schmidlin (15) , R. Stübi (16)

1 LISA (UMR_7583) - Laboratoire Interuniversitaire des Systèmes Atmosphériques
2 IMK - Institute for Meteorology and Climate Research
3 TROPO - LATMOS
4 LPMAA - Laboratoire de Physique Moleculaire pour l'Atmosphere et l'Astrophysique
5 Spectroscopie de l'atmosphère, Service de Chimie Quantique et Photophysique
6 Meteorological Observatory Hohenpeissenberg (MOHp)
7 MOL-RAO - Lindenberg Meteorological Observatory - Richard Assmann Observatory
8 ESRL - NOAA Earth System Research Laboratory
9 Department of Applied Physics [Eindhoven]
10 FMI - Finnish Meteorological Institute
11 JMA - Japan Meteorological Agency
12 AEMet - Agencia Estatal de Meteorología
13 Irish Meteorological Service
14 United Kingdom Met Office [Exeter]
15 GSFC - NASA Goddard Space Flight Center
16 Federal Office of Meteorology and Climatology MeteoSwiss

This paper presents a first statistical validation of tropospheric ozone products derived from measurements of the IASI satellite instrument. Since the end of 2006, IASI (Infrared Atmospheric Sounding Interferometer) aboard the polar orbiter Metop-A measures infrared spectra of the Earth's atmosphere in nadir geometry. This validation covers the northern mid-latitudes and the period from July 2007 to August 2008. Retrieval results from four different sources are presented: three are from scientific products (LATMOS, LISA, LPMAA) and the fourth one is the pre-operational product distributed by EUMETSAT (version 4.2). The different products are derived from different algorithms with different approaches. The difference and their implications for the retrieved products are discussed. In order to evaluate the quality and the performance of each product, comparisons with the vertical ozone concentration profiles measured by balloon sondes are performed and lead to estimates of the systematic and random errors in the IASI ozone products (profiles and partial columns). A first comparison is performed on the given profiles; a second comparison takes into account the altitude dependent sensitivity of the retrievals. Tropospheric columnar amounts are compared to the sonde for a lower tropospheric column (surface to about 6 km) and a "total" tropospheric column (surface to about 11 km). On average both tropospheric columns have small biases for the scientific products, less than 2 Dobson Units (DU) for the lower troposphere and less than 1 DU for the total troposphere. The comparison of the still pre-operational EUMETSAT columns shows higher mean differences of about 5 DU.

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]

C. Keim, M. Eremenko, J. Orphal, G. Dufour, J.-M. Flaud, et al.. Tropospheric ozone from IASI: comparison of different inversion algorithms and validation with ozone sondes in the northern middle latitudes. Atmospheric Chemistry and Physics, 2009, 9 (24), pp.9329-9347. ⟨10.5194/acp-9-9329-2009⟩. ⟨hal-00382538⟩