Impact of different sources of precursors on an ozone pollution outbreak over Europe analysed with IASI+GOME2 multispectral satellite observations and model simulations

We examine the impact of different sources of ozone precursors on the daily evolution of successive ozone pollution outbreaks across Europe in July 2017 by using a multispectral satellite approach called IASI+GOME2 and a tropospheric chemistry reanalysis named TCR-2. IASI+GOME2, combining IASI (Infrared Atmospheric Sounding Interferometer) and GOME-2 (Global Ozone Monitoring Experiment-2) measurements respectively in the infrared and the ultraviolet, allows the observation of the daily horizontal distribution of ozone in the lowermost troposphere (defined here as the atmospheric layer between the surface and 3 km above sea level). IASI+GOME2 observations show a fair capacity to depict near-surface ozone evolution as compared to surface measurements from 188 European stations for the period 15–27 July 2017. At the beginning of this event (on 16 July), an ozone outbreak is initially formed over the Iberian Peninsula likely linked with high temperature-induced enhancements of biogenic volatile organic compound concentrations and collocated anthropogenic emissions. In the following days, the ozone plume splits into two branches, one being transported eastward across the western Mediterranean and Italy and the other one over western and Central Europe. The southern branch encounters ozone precursors emitted over the Balkan Peninsula by wildfires along the coast of the Adriatic Sea and biogenic sources in the inland region of the peninsula. Ozone concentrations of the northern plume are enhanced by photochemical production associated with anthropogenic sources of ozone precursors over Central Europe and by mixing with an ozone plume arriving from the North Sea that was originally produced over North America. Finally, both ozone branches are transported eastwards and mix gradually as they reach the northern coast of the Black Sea. There, emissions from agricultural fires after harvesting clearly favour photochemical production of ozone within the pollution plume, which is advected eastwards in the following days. Based on satellite analysis, this paper shows the interplay of various ozone precursor sources to sustain a 2-week-long ozone pollution event over different parts of Europe.</p

The 2015 edition of the GEISA spectroscopic database

The GEISA database (Gestion et Etude des Informations Spectroscopiques Atmosphériques: Management and Study of Atmospheric Spectroscopic Information) has been developed and maintained by the ARA/ABC(t) group at LMD since 1974. GEISA is constantly evolving, taking into account the best available spectroscopic data. This paper presents the 2015 release of GEISA (GEISA-2015), which updates the last edition of 2011 and celebrates the 40th anniversary of the database. Significant updates and additions have been implemented in the three following independent databases of GEISA. The “line parameters database” contains 52 molecular species (118 isotopologues) and transitions in the spectral range from 10−6 to 35,877.031 cm−1, representing 5,067,351 entries, against 3,794,297 in GEISA-2011. Among the previously existing molecules, 20 molecular species have been updated. A new molecule (SO3) has been added. HDO, isotopologue of H2O, is now identified as an independent molecular species. Seven new isotopologues have been added to the GEISA-2015 database. The “cross section sub-database” has been enriched by the addition of 43 new molecular species in its infrared part, 4 molecules (ethane, propane, acetone, acetonitrile) are also updated; they represent 3% of the update. A new section is added, in the near-infrared spectral region, involving 7 molecular species: CH3CN, CH3I, CH3O2, H2CO, HO2, HONO, NH3. The “microphysical and optical properties of atmospheric aerosols sub-database” has been updated for the first time since 2003. It contains more than 40 species originating from NCAR and 20 from the ARIA archive of Oxford University. As for the previous versions, this new release of GEISA and associated management software facilities are implemented and freely accessible on the AERIS/ESPRI atmospheric chemistry data center website

TAPAS, a web-based service of atmospheric transmission computation for astronomy

Context. Spectra of astronomical targets acquired from ground-based instruments are affected by the atmospheric transmission. Aims. The authors and their institutes are developing a web-based service, TAPAS (Transmissions Atmosphériques Personnalisées pour l’AStronomie, or Transmissions of the AtmosPhere for AStromomical data). This service, freely available, is developed and maintained within the atmospheric ETHER data center. Methods. TAPAS computes the atmospheric transmission in the line-of-sight (LOS) to the target indicated by the user. The user files a request indicating the time, ground location, and either the equatorial coordinates of the target or the zenith angle of the LOS. The actual atmospheric profile (temperature, pressure, humidity, ozone content) at that time and place is retrieved from the ETHER atmospheric database (from a combination of ECMWF meteorological field and other information), and the atmospheric transmission is computed from LBLRTM software and HITRAN database for a number of gases: O2, H2O, O3, CO2, CH4, N2O, and Rayleigh extinction. The first purpose of TAPAS output is to allow identifying observed spectral features having an atmospheric or astrophysical origin. The returned transmission may also serve for characterizing the spectrometer on the wavelength scale and instrument line spectral function (ILSF) by comparing one observed spectrum of an atmospheric feature to the transmission. Finally, the top of atmosphere (TOA) spectrum may be obtained either by division of the observed spectrum by the computed transmission or other techniques developed on purpose. The obtention of transmissions for individual species allows more potentialities and better adjustments to the data. Results. In this paper, we briefly describe the mechanism of computation of the atmospheric transmissions, and we show some results for O2 and H2O atmospheric absorption. The wavelength range is presently 500–2500 nm, but may be extended in the future. Conclusions. It is hoped that this service will help many astronomers in their research. The user may also contribute to the general knowledge of the atmospheric transmission, if he/she finds systematic discrepancies between synthetic transmissions and the observed spectra. This has already happened in the recent past

The IASI/AERIS portal: dissemination of atmospheric data in open access

International audienc

The IASI/AERIS portal: dissemination of atmospheric data in open access

International audienc

The IASI/AERIS portal: dissemination of atmospheric data in open access

International audienc

The IASI/AERIS portal: dissemination of atmospheric data in open access

International audienc

The IASI/AERIS portal: dissemination of atmospheric data in open access

International audienc