Linking NO2 surface concentration and integrated content in the urban developed atmospheric boundary layer

Elsa Dieudonné (1, 2) , François Ravetta (2) , Jacques Pelon (2) , Florence Goutail (3) , Jean-Pierre Pommereau (3)

1 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
2 TROPO - LATMOS
3 STRATO - LATMOS

A statistical linear relationship between NO2 surface concentration and its integrated content in the atmospheric boundary layer (ABL) is established in urban conditions, using ABL depth as an ancillary parameter. This relationship relies on a unique data set including 20 months of observations from a ground-based UV-visible light spectrometer and from an aerosol lidar, both located in Paris inner city center. Measurements show that in all seasons, large vertical gradients of NO2 concentration exist in Paris developed ABL, explaining why the average concentration retrieved is only about 25% of NO2 surface concentration. This result shows that the commonly used hypothesis of constant mixing ratio in the ABL is not valid over urban areas, where large NOx emissions occur. Moreover, the relationship obtained is robust, and the studied area lacks of any particular orographic features, so that our results should be more widely applicable to pollution survey from space-borne observations.

Mots clés: Nitrogen dioxide; remote-sensing; vertical mixing

Domaines: Océan, Atmosphère; Physique Atmosphérique et Océanique [physics.ao-ph]

Elsa Dieudonné, François Ravetta, Jacques Pelon, Florence Goutail, Jean-Pierre Pommereau. Linking NO2 surface concentration and integrated content in the urban developed atmospheric boundary layer. Geophysical Research Letters, 2013, 40, pp.1247-1251. ⟨10.1002/GRL.50242⟩. ⟨hal-01058416⟩