High spatial resolution measurements of NO2 applying Topographic Target Light scattering-Differential Optical Absorption Spectroscopy (ToTaL-DOAS) E. Frins1, U. Platt2, and T. Wagner3 1Instituto de Física, Facultad de Ingeniería, J. Herrera y Reissig 565, 11300 Montevideo, Uruguay 2Institut für Umweltphysik, University of Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany 3Max-Planck-Institut für Chemie, Becherweg 27, 55128 Mainz, Germany
Abstract. Topographic Target Light scattering – Differential Optical Absorption
Spectroscopy (ToTaL-DOAS), also called Target-DOAS, is a novel experimental
procedure to retrieve trace gas concentrations present in the low
atmosphere. Scattered sunlight (diffuse or specular) reflected from natural
or artificial targets located at different distances are analyzed to
retrieve the spatial distribution of the concentration of different trace
gases like NO2, SO2 and others. We report high spatial resolution
measurements of NO2 mixing ratios in the city of Montevideo
(Uruguay) observing three buildings as targets with a Mini-DOAS instrument.
Our instrument was 146 m, 196 m, and 280 m apart from three different
buildings located along a main Avenue. We obtain temporal variation of
NO2 mixing ratios between 30 ppb and 65 ppb from measurements of
November 2007 and mixing ratios up to 50 ppb from measurements of August and
September 2008. Our measurements demonstrate that ToTaL-DOAS observations
can be made over relative short distances. In polluted air masses, the
retrieved absorption signal was found to be sufficiently strong to allow
measurements over distances in the range of several tens of meters.
Citation: Frins, E., Platt, U., and Wagner, T.: High spatial resolution measurements of NO2 applying Topographic Target Light scattering-Differential Optical Absorption Spectroscopy (ToTaL-DOAS), Atmos. Chem. Phys., 8, 7595-7601, doi:10.5194/acp-8-7595-2008, 2008.