Air Quality: Nitrogen Dioxide

(Source: KNMI)

The trace gas NO2 is emitted into the atmosphere in large quantities due to human activities such as traffic and industry. The residence time of NOx in the lower troposphere is short. Therefore observations of tropospheric NO2 contain important information on the emissions of nitric oxide, and the trends in these emissions. In the maps of troposheric NO2 made from SCIAMCHY and OMI observations the industrialised areas in the world are clearly visible. But also phenomena as the weekly cycle of traffic and industry and the major shiptracks on the ocean can be observed in these maps from satellite observations.

Shiptracks visible in measured nitrogen dioxide from space

(shiptrack) Ship tracks seen in the troposheric NO2 concentrations retrieved from satellite obseravtions. This image shows an annual mean of SCIAMACHY observations in the year 2004. The shiptracks are clearly visible on the route from Taiwan to Singapore, then to Atjeh, from Atjeh to the South point of India, and in the Suez-canal and the Red sea.

Week cycle visible in measured air pollution over Europe

(sunday) (wednesday) When the NO2 concentrations are averaged per weekday, as is done in these two pictures for Sunday and Wednesday in the period 2005-2007 measured by OMI, the concentrations in Europe are much higher at the working days than on Sunday. A similar effect is found for Israel on Saturday and on Friday for Islamitic countries.

Maps of measured nitrogen dioxide from space

(world) World
The measured mean tropospheric NO2 for 2008 as measured with the satellite instrument SCIAMACHY. Hotspots on these world map are the industrialised area in Europe, China, the USA and South-Africa. A lot of other mega-cities can also be found as a localised spot with enhanced NO2 concentrations.
(europe) Europe
Within Europe the highest concentration are found in the Po-valley, Moscow and the region from London via the Netherlands/Belgium to the Ruhr area. All these areas have a high population and traffic density causing this pollution. (Image of 2007 from OMI)
(italy) Italy
In this map of Italy in 2004 a clear signature of the cities along the coast is visible, but the eye is immediately drawn to the red collored Po-Valley. The Po-Valley is surrounded by mountain ridges confining the emitted pollution to this region.
(netherlands) The Netherlands
The South of the Netherlands, Flemish Belgium and the Ruhr area are all suffering from a lot of traffic and industry. The image is an average over 2006 and has a linear scale contrary to the images above.

Further information


Ronald van der A, last modified: May 2009