Contribution of lidar observations to urban boundary layer NO2 analysis

Elsa Dieudonné 1, 2 François Ravetta 2 Jacques Pelon 2 Florence Goutail 3 Andrea Pazmino 3
2 TROPO - LATMOS
LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
3 STRATO - LATMOS
LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
Abstract : The Paris agglomeration is a major source of pollutants that can stay trapped in the atmospheric boundary layer (BL), making BL depth a crucial parameter that modulates pollutant concentrations and peak intensity. It is commonly assumed that pollutants, except very short-lived species, are well mixed in the BL, implying that the BL integrated content (column) can easily compare with ground-based in-situ measurements using BL depth. On a few day case study chosen during the MEGAPOLI field campaign, we analyze Airparif in-situ air quality measurements at ground level and at the Eiffel Tower summit and interpret the differences using BL observations from an elastic backscatter lidar located in Qualair station, in central Paris. NO2 concentrations are generally higher in the surface layer than in the mixed layer meaning NO2 is not well distributed in the BL. During the afternoons of pollution peak days, the gradient is around -41 μg/m3/km but when the morning BL is rising there is no gradient. Then we calculate NO2 integrated columns, first assuming a constant concentration in the mixed layer and no surface layer. These calculated columns reproduce the temporal structure of the columns measured by the Qualair UV-visible spectrometer (SAOZ) but they are 4 time higher in average. Columns calculated using a linearly decreasing concentration profile fit better with the SAOZ and confirm the existence of a vertical NO2 gradient.
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https://hal.archives-ouvertes.fr/hal-00832950
Contributor : Catherine Cardon <>
Submitted on : Tuesday, June 11, 2013 - 4:24:16 PM
Last modification on : Friday, January 10, 2020 - 3:42:33 PM

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  • HAL Id : hal-00832950, version 1

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Elsa Dieudonné, François Ravetta, Jacques Pelon, Florence Goutail, Andrea Pazmino. Contribution of lidar observations to urban boundary layer NO2 analysis. 25th International Laser Radar Conference (ILRC), Jul 2010, Nara, Japan. ⟨hal-00832950⟩

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