High spatial resolution measurements of NO₂ applying Topographic Target Light scattering-Differential Optical Absorption Spectroscopy (ToTaL-DOAS)

E. Frins (1) , U. Platt (2) , T. Wagner (3)

1 Instituto de Física
2 Institut für Umweltphysik [Heidelberg]
3 MPIC - Max-Planck-Institut für Chemie

Tomographic 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 (partially or totally) reflected from natural or artificial targets of similar albedo located at different distances is analyzed to retrieve 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 apart from the first building, 196 m from the second and 286 m from the third one. All three buildings are located along a main Avenue. We obtain temporal variation of NO₂ mixing ratios between 30 ppb and 65 ppb (±2 ppb). Our measurements demonstrate that ToTaL-DOAS measurements can be made over very short distances. In polluted air masses, the retrieved absorption signal was found to be strong enough to allow measurements over distances in the range of several ten meters, and achieve a spatial resolution of 50 m approximately.

Domaines: Océan, Atmosphère

E. Frins, U. Platt, T. Wagner. High spatial resolution measurements of NO₂ applying Topographic Target Light scattering-Differential Optical Absorption Spectroscopy (ToTaL-DOAS). Atmospheric Chemistry and Physics Discussions, 2008, 8 (3), pp.10257-10273. ⟨hal-00304216⟩