NO₂ lidar profile measurements for satellite interpretation and validation

Abstract

[1] Satellite instruments are efficient detectors of air pollutants such as NO 2 . However, the interpretation of satellite retrievals is not a trivial matter. We describe a novel instrument, the RIVM NO 2 mobile lidar, to measure tropospheric NO 2 profiles for the interpretation and validation of satellite data. During the DANDELIONS campaign in 2006 we obtained an extensive collection of lidar NO 2 profiles, coinciding with OMI and SCIAMACHY overpasses. On clear days and early mornings a comparison between lidar and in situ measurements showed excellent agreement. At other times the in situ monitors with molybdenum converters suffered from NO y interference. The lidar NO 2 profiles indicated a well-mixed boundary layer, with high NO 2 concentrations in the boundary layer and concentrations above not differing significantly from zero. The boundary layer concentrations spanned a wide range, which likely depends on the wind directions and on the intensity of local (rush hour) traffic which varies with the day of the week. Large diurnal differences were mainly driven by the height of the boundary layer, although direct photolysis or photochemical processes also contribute. Small-scale temporal and spatial variations in the NO 2 concentrations of the order of 20-50% were measured, probably indicative of small-scale eddies. A preliminary comparison between satellite and lidar data shows that the satellite data tend to overestimate the amount of NO 2 in the troposphere compared to the lidar data.

DOAS measurements of NO<sub>2</sub> from an ultralight aircraft during the Earth Challenge expedition

“…Boersma et al (2009) also assumed a homogeneous boundary layer to compare in-situ surface NO 2 concentrations with SCIAMACHY (SCanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY) and OMI columns. This is also confirmed by the few tropospheric NO 2 lidar measurements available (Volten et al, 2009). Considering aerosol extinction, the many lidar profiles available in polluted zones (e.g.…”

Field test of available methods to measure remotely SO<sub>x</sub> and NO<sub>x</sub> emissions from ships

“…Schlager et al, 2008;Eyring et al, 2010;Lack et al, 2011), including a study performed subsequently on Stena Hollandica (Moldanová et al, 2013) and seems thus to be a commonly observed phenomenon. Partially this can be caused by the fact that also SO 3 and sulphuric acid are formed by the combustion of sulphur containing fuels.…”

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

“…No measurements are available for this site for the same period as for De Bilt. In 2005 and 2006 the DANDELIONS (Dutch Aerosol and Nitrogen Dioxide Experiments for vaLIdation of OMI and SCIAMACHY) campaigns (Brinksma et al, 2008;Volten et al, 2009) were held here, and in 2009 the CINDI (Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments) campaign (Piters et al, 2012). During both campaigns there were indications at Cabauw of aged air coming from, e.g., the Ruhr area.…”

“…It is assumed here that NO 2 is homogeneously distributed in the boundary layer, and that no NO 2 is present above the boundary layer. Lidar observations of NO 2 profiles show that this is often the case; see e.g., Volten et al (2009). The boundary layer height (H b ) is taken from ECMWF forecasts.…”