ATMOCHEM - Integrated analysis of long-range pollution transport to mid- and high-latitudes over Europe using model simulations, satellite observations, and aircraft measurements (INTAS)
Final Report Abstract
In this project, satellite observations of nitrogen dioxide in the atmosphere have been used to investigate the occurrence of long range transport of pollution over the oceans. Such export of pollution is important as it affects air quality in clean regions, changes background levels of pollutants in large parts of the world and is relevant for international conventions such as LRTAP. Nitrogen dioxide is a tracer of pollution which is mainly produced in the combustion of fossil fuels but also by biomass burning and lightning. As the atmospheric lifetime of NO2 is short, long range transport is only possible at high wind speed, preferably at low solar irradiation (mid and high latitudes in fall and winter). In standard satellite products of tropospheric NO2 there is little evidence for long range transport. This is due to the fact that such transport is often linked to the presence of clouds, and cloudy data is usually excluded from the satellite data sets as in such cases, the instrument does not have an unobstructed view to the surface where most of the pollution is located. Therefore, in this study all NO2 data from the European GOME-2 satellite instrument have been used and a simplified treatment of the effect of clouds on the detection sensitivity has been developed. It assumes that in long range transport events in the presence of clouds, the NO2 is well mixed within the cloud. This assumption is supported by some case studies on CO measurements in the atmosphere and NO2 data from atmospheric models. Using measurements from several days, long range transport events can be identified in the satellite data using image processing techniques and the assumptions that a) NO2 plumes from transport are short lived and can therefore be identified by evaluating deviations from the mean values and b) that they are contiguous in space and c) that they can be traced back to regions with elevated NO2 values. An algorithm based on these principles has been developed and implemented, and a multi-annual data set of GOME-2 measurements has been evaluated, identifying nearly 4000 individual NO2 transport events over oceans. Using this data set, a statistical evaluation of NO2 long range transport events could be performed. The results show, that the main regions affected by NO2 from long range transport are between the US and Europe, in the outflow of China and East of South America and South Africa. In all regions, most events are observed in fall and winter. For Europe and China, mainly short lived events are observed as NO2 plumes are often rapidly transported back over the continent where they cannot be detected by the algorithm. While from South Africa and the Eastern US many well defined transport events can be traced in the satellite data, the quantitative NO2 export is largest from China, followed by Europe. In total, an NO2 outflow of 50 GgN/a is computed for the four main NO2 export regions which is small in comparison to total NOx emissions but significant for atmospheric chemistry downwind of the US, Europe, China and South Africa. The data set created provides a first estimate of global NO2 transport over the oceans and can be used to evaluate the ability of current atmospheric models to simulate pollution export from the continents. Further refinements with data from other satellite instruments and more detailed modelling of measurement sensitivity in cloudy situations could reduce the uncertainties of the estimates made.
Publications
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Cloud effects on tropospheric NO2 measurements from satellite, A. Zien, DPG Spring meeting, Hannover, Germany, March 2010
Zien, A., Richter, A., Hilboll, A., Burrows, J.P.
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GOME-2 satellite observations of NOx emissions from ships, DPG Spring meeting, Hannover, Germany, March 2010
Richter, A., Hilboll, A., Zien, A., Burrows, J.P.
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GOME-2 satellite observations of NOx emissions from ships, EGU General Assembly 2010, Vienna, Austria, 2nd to 7th May 2010
Richter, A., Hilboll, A., Zien, A., Burrows, J.P.
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Sensitivity of satellite observations over bright and cloudy scenes, COSPAR 38th scientific assembly, Bremen, Germany, 18 - 25 July 2010
Zien, A., Richter, A., Hilboll, A., Burrows, J.P.
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Aerosol Effects on Satellite Observations of NO2 Pollution, 3rd Urbino Sympsium, Urbino, Italy, 13 - 16 September 2011
Leitão, J., Hilboll, A., Richter, A., Zien, A., Burrows, J.P.
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Cloud effects in satellite observed tropospheric NO2, EGU General Assembly, Vienna, Austria, April 2011
Richter, A., Hilboll, A., Zien, A., Burrows, J.P.
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Long-term observations of pollution from space, IUGG 2011, Melbourne, Australia, 28 June - 7 July 2011
Richter, A., Wittrock, F., Hilboll, A., Leitão, J, Zien, A., Vrekoussis, M., Burrows, J.P.
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Remote sensing trace gas observations by satellite instruments over bright surfaces, DPG Spring meeting, Dresden, Germany, March 2011
Zien, A., Richter, A., Hilboll, A., Burrows, J.P.
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Satellite observations of biomass burning NO2, DPG Spring meeting, Dresden, Germany, March 2011
Richter, A., Leitão, J., Hilboll, A., Zien, A., Burrows, J.P.
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Comparison of NO2 long-range transport events in GOME-2 observations and CTM simulations, EGU General Assembly, Vienna, Austria, April 2012
Zien, A., Richter, A., Hilboll, A., Burrows, J.P.
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Systematic quantitative analysis of NO2 long-range transport events and comparison to model data, AGU Fall meeting, San Francisco, USA, December 2012
Zien, A.; Richter, A.; Hilboll, A., Burrows, J.P.
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Systematic analysis of tropospheric NO2 long-range transport events detected in GOME-2 satellite data, Atmos. Chem. Phys., 14, 7367-7396, 2014
Zien, A. W., Richter, A., Hilboll, A., Blechschmidt, A.-M., and Burrows, J. P.
