MAX-DOAS tropospheric nitrogen dioxide column measurements compared with the Lotos-Euros air quality model

T. Vlemmix, H. J. Eskes, A. J. M. Piters, H. Kelder, P. F. Levelt
2011 Atmospheric Chemistry and Physics Discussions  
A 14-month data set of MAX-DOAS (Multi-Axis Differential Optical Absorption Spectroscopy) tropospheric NO 2 column observations in De Bilt, the Netherlands, has been compared with the regional air quality model Lotos-Euros. The model was run on a 7×7 km 2 grid, the same resolution as the emission inventory used. A study was performed to assess the effect of clouds on the retrieval accuracy of the MAX-DOAS observations. Good agreement was found between modeled and measured tropospheric NO 2
more » ... pospheric NO 2 columns, with an average difference of less than 1 % of the average tropospheric column (14.5·10 15 molec cm −2 ). The comparisons show little cloud cover dependence after cloud corrections for which ceilometer data were used. Hourly differences between observations and model show a Gaussian behavior with a standard deviation (σ ) of 5.5 · 10 15 molec cm −2 . For daily averages of tropospheric NO 2 columns, a correlation of 0.72 was found for all observations, and 0.79 for cloud free conditions. The measured and modeled tropospheric NO 2 columns have an almost identical distribution over the wind direction. A significant difference between model and measurements was found for the average weekly cycle, which shows a much stronger decrease during the weekend for the observations; for the diurnal cycle, the observed range is about twice as large as the modeled range. The results of the comparison demonstrate that averaged over a long time period, the tropospheric NO 2 column observations are representative for a large spatial area despite the fact that they were obtained in an urban region. This makes the MAX-DOAS technique especially suitable for validation of satellite observations and air quality models in urban regions. Published by Copernicus Publications on behalf of the European Geosciences Union. Atmos. Chem. Phys., 15, 1313-1330, 2015
doi:10.5194/acpd-11-28895-2011 fatcat:bocp2avsjncprmxd7is2tii33i