In the following diagrams we show air quality measurements from different stations in the same region in Germany for the days May 17th + 18th 2007. We compare three different places, one in the vicinity to a busy street (Koblenz), one in a commercial and industrial area next to a medium-sized town (Neuwied) and one in the forest not too far from settlements (Neuhäusel).
Where are the stations located?
We show Google Earth satellite images of the surroundings. Click on them in order to make them larger.
1. a + b) Koblenz, Friedrich Ebert Ring. The station is indicted by the red circle. It is located not far from the city centre. Image left: Google Earth Image right: Peter Jansen, licenced for Panoramio.com
2. Neuwied, commercial and industrial park next to the Rhine river. Image: Google Earth
3. Station Neuhäusel forest. Image: Google Earth
Nitric oxide and ozone
We compare nitric oxide (= nitrogen monoxide) and ozone values in Koblenz and Neuwied. At the forest station Neuhäusel nitric oxide is not detectable, because it can be found only close to the sources and is afterwards oxidised in the air. In particular in the morning nitric oxide increases with the emerging traffic (Koblenz). But as soon as the amount of ozone formed increases as well, it disappears again.
4. a + b NO and O3 concentrations in Koblenz and Neuwied.
Source: All graphs are taken from the website of the air measurement network Rheinland-Pfalz
Nitrogen dioxide and ozone
We compare nitrogen dioxide and ozone at the three stations.
5. a - c) NO2 and O3 measurements in Koblenz ...
... Neuwied ...
... and Neuhäusel.
6. Wind direction and temperature curves are shown for Neuwied. The second day is warmer.
Nitrogen dioxide concentrations are higher in the towns. But for ozone this is not the case. Ozone formation and depletion depends on several factors. They can favour formation in the countryside and depletion in the city. Ozone is also transported with the wind.
Direct comparison of the stations
We compare nitrogen dioxide and ozone for the three stations in one graph: Koblenz = blue, Neuwied = red, Neuhäusel = green
7. NO2 comparison of all stations.
8. O3 comparisons of all stations.
9. NO comparison of Koblenz and Neuwied.
We can see that ozone is clearly going down in the city and next to the town of Neuwied during the night. This is not the case at the station in the forest. Therefore we can conclude, that ozone is more subject to depleting reactions in cities and in the urban environment.
We can see that NO levels are higher in the city (Koblenz) than around the city (Neuwied).
