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

Abstract

Abstract. 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 Correspondence to: M. Eremenko (maxim.eremenko@lisa.univ-paris12.fr) 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 DobsonPublished by Copernicus Publications on behalf of the European Geosciences Union. C. Keim et al.: IASI tropospheric ozone validationUnits (DU) for the lower troposphere and less than 1 DU for the total troposphere. The comparison of the still preoperational EUMETSAT columns shows higher mean differences of about 5 DU.

Ozone climatology and its variability from ground based and satellite observations over Irene, South Africa (25.5º S; 28.1º E) – Part 2: Total column ozone variations

“…A validation exercise performed on IASI using balloonsonde measurements indicated that total column measurements and the retrieval errors are less than 5%. This is consistent with the standard deviation difference between the ozonesondes and IASI data (Keim et al, 2009). More details on IASI instrument can be found in http://www.ospo.…”

“…OMI provides data to derive ozone as well as to measure cloud pressure and coverage. OMI has high spectral capability, which improves the level of precision and accuracy of ToZ (Keim et al, 2009). It uses a linear fit algorithm for the retrieval of ToZ.…”

Extending the satellite data record of tropospheric ozone profiles from Aura-TES to MetOp-IASI: characterisation of optimal estimation retrievals

“…Validation with and comparison to independent measurements of other IASI products have been performed Keim et al, 2009;Pittman et al, 2009;Viatte et al, 2011;Dufour et al, 2012;Pommier et al, 2012;Scannell et al, 2012;Gazeaux et al, 2013) and also comparison to models (Parrington et al, 2012). In general, these studies focus on the determination of the bias and the correlation with respect to independent measurements and on the determination of the information content.…”

“…In general, these studies focus on the determination of the bias and the correlation with respect to independent measurements and on the determination of the information content. Only Keim et al (2009) and Dufour et al (2012) also studied the precision of the retrievals.…”

Towards the retrieval of tropospheric ozone with the Ozone Monitoring Instrument (OMI)

“…In their work, Eremenko et al (2008) used ozone profiles retrieved with an analytical altitude-dependent regularization method from the Infrared Atmospheric Sounding Interferometer (IASI; Clerbaux et al, 2009) data. IASI ozone profiles have been thoroughly validated for example by Keim et al (2009) and Dufour et al (2012). In the second case study, we compared the operational and modified ozone profiles against ozonesonde data from North America for AugustSeptember 2006.…”