Tropospheric ozone distributions over Europe during the heat wave in July 2007 observed from infrared nadir spectra recorded by IASI

Eremenko, Maxim; Dufour, G.; Forêt, Gilles; Keim, C.; Orphal, J.; Beekmann, Matthias; Bergametti, Gilles; Flaud, J.‐M.

doi:10.1029/2008gl034803

Cited by 129 publications

(168 citation statements)

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“…Kulawik et al (2006) first introduced altitude-dependent constraint matrices in regularisation schemes for the retrieval of trace gases vertical profiles. The regularisation method used in our simulator has been optimised for lower tropospheric ozone observations using IASI (Infrared Atmospheric Sounding Interferometer) measurements (Eremenko et al, 2008). This inversion algorithm uses seven spectral micro-windows in the range 975-1100 cm −1 to avoid carbon dioxide and water vapour impact on the ozone retrievals.…”

Section: Full Radiative Transfer Calculationsmentioning

confidence: 99%

“…This inversion algorithm uses seven spectral micro-windows in the range 975-1100 cm −1 to avoid carbon dioxide and water vapour impact on the ozone retrievals. This algorithm minimises a cost function calculated with the degrees of freedom of the signal (DOF) and the error in the lower troposphere, aimed at the maximisation of the sensitivity in the lower troposphere while retaining a reasonable error (Eremenko et al, 2008;Dufour et al, 2012). The KOPRAfit also provides the AKs, that can be used to derive the information on the vertical sensitivity of the observations to the "true" NR ozone profile.…”

Section: Full Radiative Transfer Calculationsmentioning

confidence: 99%

“…A radiative transfer model is then used to simulate the spectra observations for each scene. As the forward radiative transfer model we use the Karlsruhe Optimized and Precise Radiative transfer Algorithm (KOPRA) (Stiller et al, 2002), adapted to the nadir geometry (Eremenko et al, 2008). The MAGEAQ observing system is simulated taking into account its spectral resolution, radiometric noise and observation geometry.…”

Section: Full Radiative Transfer Calculationsmentioning

confidence: 99%

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The effect of using limited scene-dependent averaging kernels approximations for the implementation of fast observing system simulation experiments targeted on lower tropospheric ozone

et al. 2013

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Practical implementations of chemical OSSEs (Observing System Simulation Experiments) usually rely on approximations of the pseudo-observations by means of a predefined parametrization of the averaging kernels, which describe the sensitivity of the observing system to the target atmospheric species. This is intended to avoid the use of a computationally expensive pseudo-observations simulator, that relies on full radiative transfer calculations. Here we present an investigation on how no, or limited, scene dependent averaging kernels parametrizations may misrepresent the sensitivity of an observing system. We carried out the full radiative transfer calculation for a three-days period over Europe, to produce reference pseudo-observations of lower tropospheric ozone, as they would be observed by a concept geostationary observing system called MAGEAQ (Monitoring the Atmosphere from Geostationary orbit for European Air Quality). The selected spatio-temporal interval is characterised by an ozone pollution event. We then compared our reference with approximated pseudo-observations, following existing simulation exercises made for both the MAGEAQ and GEOstationary Coastal and Air Pollution Events (GEO-CAPE) missions. We found that approximated averaging kernels may fail to replicate the variability of the full radiative transfer calculations. In addition, we found that the approximations substantially overestimate the capability of MAGEAQ to follow the spatio-temporal variations of the lower tropospheric ozone in selected areas, during the mentioned pollution event. We conclude that such approximations may lead to false conclusions if used in an OSSE. Thus, we recommend to use comprehensive scene-dependent approximations of the averaging kernels, in cases where the full radiative transfer is computationally too costly for the OSSE being investigated

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Section: Full Radiative Transfer Calculationsmentioning

confidence: 99%

Section: Full Radiative Transfer Calculationsmentioning

confidence: 99%

Section: Full Radiative Transfer Calculationsmentioning

confidence: 99%

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The effect of using limited scene-dependent averaging kernels approximations for the implementation of fast observing system simulation experiments targeted on lower tropospheric ozone

et al. 2013

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“…Finally, we evaluated the modifications done to the algorithm with two case studies. In the first case study, we compared the operational and the modified retrievals of tropospheric ozone over Europe to the results presented in the paper by Eremenko et al (2008). 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.…”

Section: Introductionmentioning

confidence: 99%

“…In the first case study, we compared the operational and the modified retrievals of tropospheric ozone over Europe to the results presented in the paper by Eremenko et al (2008). 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).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2015

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Abstract.We have assessed the sensitivity of the operational Ozone Monitoring Instrument (OMI) ozone profile retrieval algorithm to a number of a priori and radiative transfer assumptions. We studied the effect of stray light correction, surface albedo assumptions and a priori ozone profiles on the retrieved ozone profile. Then, we studied how to modify the algorithm to improve the retrieval of tropospheric ozone. We found that stray light corrections have a significant effect on the retrieved ozone profile but mainly at high altitudes. Surface albedo assumptions, on the other hand, have the largest impact at the lowest layers. Choice of an ozone profile climatology which is used as a priori information has small effects on the retrievals at all altitudes. However, the usage of climatological a priori covariance matrix has a significant effect. Based on these sensitivity tests, we made several modifications to the retrieval algorithm: the a priori ozone climatology was replaced with a new tropopause-dependent climatology, the a priori covariance matrix was calculated from the climatological ozone variability values, and the surface albedo was assumed to be linearly dependent on wavelength in the 311.5-330 nm channel. As expected, we found that the a priori covariance matrix basically defines the vertical distribution of degrees of freedom for a retrieval. Moreover, our case study over Europe showed that the modified version produced over 10 % smaller ozone abundances in the troposphere which reduced the systematic overestimation of ozone in the retrieval algorithm and improved correspondence with Infrared Atmospheric Sounding Instrument (IASI) retrievals. The comparison with ozonesonde measurements over North America showed that the operational retrieval performed better in the upper troposphere/lower stratosphere (UTLS), whereas the modified version improved the retrievals in the lower troposphere and upper stratosphere. These comparisons showed that the systematic biases in the OMI ozone profile retrievals are not caused by the a priori information but by some still unidentified problem in the radiative transfer modelling. Instead, the a priori information pushes the systematically wrong ozone profiles towards the true values. The smaller weight of the a priori information in the modified retrieval leads to better visibility of tropospheric ozone structures, because it has a smaller tendency to damp the variability of the retrievals in the troposphere. In summary, the modified retrieval unmasks systematic problems in the radiative transfer/instrument model and is more sensitive to tropospheric ozone variation; that is, it is able to capture the tropospheric ozone morphology better.

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Ozone pollution: What can we see from space? A case study

Forêt

Eremenko

Cuesta

et al. 2014

J. Geophys. Res. Atmos.

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Due to its impact on environment, tropospheric ozone received particular attention since several decades. Ground-based networks associated with regional chemical transport models are used to monitor and forecast surface ozone concentrations, but coverage, representativeness, and accuracy issues remain important. Recent satellite observations have demonstrated the capacity to probe tropospheric ozone, but there has been no explicit attempt to quantify their ability to measure ozone pollution near ground. We propose here to assess the ability of ozone sounders to detect a photochemical ozone pollution event that is supposed to be a favorable situation for satellite detection. We have chosen ozone pollution event over Europe associated with a warm conveyor belt that efficiently transports photochemically produced ozone upward. Ozone satellite products from Global Ozone Monitoring Experiment-2, Infrared Atmospheric Sounding Interferometer (IASI), and Ozone Monitoring Instrument are analyzed here for their capacity to capture such an event. Also, in situ observations and regional chemical-transport models show increasing ozone concentrations in the continental and Mediterranean boundary layer and further transport to central Europe and Scandinavia associated with upward transport. Satellite observations do not detect high ozone concentrations within the boundary layer due the weak sensitivity near the surface. Nevertheless, we have shown that the IR sounder IASI was able to detect, qualitatively and quantitatively, the ozone plume transported upward by the warm conveyor belt, suggesting that a quantification of upward transport of ozone pollution could be possible using current satellite observations. This should encourage us to further explore approaches more sensitive to surface ozone (such as the multispectral approach) and to prepare the next generation of still more sensitive spaceborne instruments.

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Tropospheric ozone distributions over Europe during the heat wave in July 2007 observed from infrared nadir spectra recorded by IASI

Cited by 129 publications

References 20 publications

The effect of using limited scene-dependent averaging kernels approximations for the implementation of fast observing system simulation experiments targeted on lower tropospheric ozone

The effect of using limited scene-dependent averaging kernels approximations for the implementation of fast observing system simulation experiments targeted on lower tropospheric ozone

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

Ozone pollution: What can we see from space? A case study

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