Articles | Volume 10, issue 4
Atmos. Meas. Tech., 10, 1281–1298, 2017
Atmos. Meas. Tech., 10, 1281–1298, 2017

Research article 03 Apr 2017

Research article | 03 Apr 2017

Potential of multispectral synergism for observing ozone pollution by combining IASI-NG and UVNS measurements from the EPS-SG satellite

Lorenzo Costantino1, Juan Cuesta1, Emanuele Emili2, Adriana Coman1, Gilles Foret1, Gaëlle Dufour1, Maxim Eremenko1, Yohann Chailleux1, Matthias Beekmann1, and Jean-Marie Flaud1 Lorenzo Costantino et al.
  • 1Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), CNRS UMR7583, Université Paris Est Créteil, Université Paris Diderot, Créteil, France
  • 2Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), Toulouse, France

Abstract. Present and future satellite observations offer great potential for monitoring air quality on a daily and global basis. However, measurements from currently orbiting satellites do not allow a single sensor to accurately probe surface concentrations of gaseous pollutants such as tropospheric ozone. Combining information from IASI (Infrared Atmospheric Sounding Interferometer) and GOME-2 (Global Ozone Monitoring Experiment-2) respectively in the TIR and UV spectra, a recent multispectral method (referred to as IASI+GOME-2) has shown enhanced sensitivity for probing ozone in the lowermost troposphere (LMT, below 3 km altitude) with maximum sensitivity down to 2.20 km a.s.l. over land, while sensitivity for IASI or GOME-2 alone only peaks at 3 to 4 km at the lowest.

In this work we develop a pseudo-observation simulator and evaluate the potential of future EPS-SG (EUMETSAT Polar System – Second Generation) satellite observations, from new-generation sensors IASI-NG (Infrared Atmospheric Sounding Interferometer – New Generation) and UVNS (Ultraviolet Visible Near-infrared Shortwave-infrared), to observe near-surface O3 through the IASI-NG+UVNS multispectral method. The pseudo-real state of the atmosphere is provided by the MOCAGE (MOdèle de Chimie Atmosphérique à Grande Échelle) chemical transport model. We perform full and accurate forward and inverse radiative transfer calculations for a period of 4 days (8–11 July 2010) over Europe.

In the LMT, there is a remarkable agreement in the geographical distribution of O3 partial columns between IASI-NG+UVNS pseudo-observations and the corresponding MOCAGE pseudo-reality. With respect to synthetic IASI+GOME-2 products, IASI-NG+UVNS shows a higher correlation between pseudo-observations and pseudo-reality, which is enhanced by about 12 %. The bias on high ozone retrieval is reduced and the average accuracy increases by 22 %. The sensitivity to LMT ozone is also enhanced. On average, the degree of freedom for signal is higher by 159 % over land (from 0.29 to 0.75) and 214 % over ocean (from 0.21 to 0.66). The mean height of maximum sensitivity for the LMT peaks at 1.43 km over land and 2.02 km over ocean, respectively 1.03 and 1.30 km below that of IASI+GOME-2. IASI-NG+UVNS also shows good retrieval skill in the surface–2 km altitude range. It is one of a kind for retrieving ozone layers of 2–3 km thickness, in the first 2–3 km of the atmosphere. IASI-NG+UVNS is expected to largely enhance the capacity to observe ozone pollution from space.

Short summary
Using current space-borne measurements from one spectral domain (TIR or UV), only ozone down to 3–4 km altitude may be observed with adequate vertical sensitivity. Here, we evaluate the potential of a new multispectral retrieval method that combines the information from TIR and UV measurements provided by the new-generation sensors IASI-NG and UVNS. Both are on board the upcoming EPS-SG satellite. This new IASI-NG+UVNS retrieval approach allows observations of ozone layers down to 2 km a.s.l.