MAX‐DOAS O₄ measurements: A new technique to derive information on atmospheric aerosols: 2. Modeling studies

Abstract

[1] A new retrieval algorithm for the determination of aerosol properties using MultiAXis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements based on nonlinear optimal estimation is presented. Using simulated MAX-DOAS measurements of the optical depth of the collision complex of oxygen (O 4 ) as well as the variation of the intensity of diffuse skylight measured at different viewing directions and wavelengths, the capability of this measurement technique to derive the aerosol extinction profile as well as information on the phase function and single scattering albedo is demonstrated. The information content, vertical resolution and retrieval errors under various atmospheric conditions are discussed. Furthermore, it is demonstrated that the assumption of a smooth variation of the aerosol properties between successive measurements can be used to improve the quality of the retrieval by applying a Kalman smoother. The results of these model studies suggest that the achievable precision of MAX-DOAS measurements of the aerosol total optical depth is better than 0.01 and thus comparable with established methods of aerosol detection by Sun photometers (e.g., within the AERONET network) over a wide range of atmospheric conditions. Moreover, MAX-DOAS measurements contain information on the vertical profile of the aerosol extinction, and can be performed with relatively simple, robust and self-calibrating instruments.

Determination of aerosol properties from MAX-DOAS observations of the Ring effect

“…The observed radiance is most sensitive to properties of the scattering processes, but is almost independent of the atmospheric light path distribution. In contrast to observations of the O 4 absorption and the Ring effect, the radiance depends strongly on the aerosol absorbing properties (see also Frieß et al, 2006).…”

“…Thus, from the measured strength of the Ring effect, information on aerosols and clouds can be obtained (Park et al, 1986;Joiner et al, , 2002Joiner et al, , 2004de Beek et al, 2001;Wagner et al,496 T. Wagner et al: Determination of aerosol properties from MAX-DOAS observations of the Ring effect this study we focus on the potential to retrieve aerosol information from observations of the Ring effect using a ground based Multi-Axis-DOAS (MAX-DOAS) instrument. MAX-DOAS instruments observe scattered sun light under a variety of elevation angles (Hönninger and Platt, 2002;Leser et al, 2003;Bobrowski et al, 2003;van Roozendael et al, 2003;Wittrock et al, 2004;Hönninger et al, 2004;Heckel et al, 2005;Wagner et al, 2004Wagner et al, , 2007bFrieß et al, 2006;Fietkau et al, 2007;Theys et al, 2007). The MAX-DOAS observations used in this study make simultaneous measurements in three different azimuth directions.…”

Investigations of the Diurnal Variation of Vertical HCHO Profiles Based on MAX-DOAS Measurements in Beijing: Comparisons with OMI Vertical Column Data

“…Detailed descriptions of the error budget can be found in a previous study [41]. The errors in aerosol extinction coefficients at altitudes higher than 2 km were ~80% because the sensitivity of the measurements decreases with increasing tropospheric altitude [44,45].…”

The Heidelberg Airborne Imaging DOAS Instrument (HAIDI) – a novel imaging DOAS device for 2-D and 3-D imaging of trace gases and aerosols

“…Tech., 7, 3459-3485, 2014 www Baidar et al, 2013;Dix et al, 2013). This is usually done in a two-stage process using inverse modeling of the atmospheric radiative transfer (e.g., Sinreich et al, 2005;Wagner et al, 2004;Frieß et al, 2006;Irie et al, 2008;Clémer et al, 2010;Wagner et al, 2011). First, the aerosol extinction profile is retrieved from the absorption of the oxygen collision complex O 4 , which has a horizontally constant atmospheric concentration (apart from pressure variations) and therefore serves as a proxy of the light path which is affected by aerosols.…”