The University of Innsbruck explains that ozone is not directly measured on the ground-level, it is rather deduced from the levels of nitrogen oxides.
The deduction is based on models which have now been found to render wrong results, overestimating ground-level ozone by up to 50%.
Ozone science is one big joke.
Air quality: doctrine needs to be revised
https://idw-online.de/de/news807693
"dr Christian Flatz
Public Relations Office at the
Long-term measurements in the city of Innsbruck show that the proportion of ground-level ozone in atmospheric models tends to be overestimated. As a consequence, a fundamental doctrine for air quality prognosis has to be reinterpreted for urban areas. The measurements by an international team led by atmospheric researcher Thomas Karl from the University of Innsbruck also show that direct nitrogen dioxide emissions are overestimated.
The 40 meter high measuring tower of the Innsbruck Atmospheric Observatory at the university crossing in the city of Innsbruck continuously supplies data on the composition of the atmosphere near the ground. 36,000 data points are recorded per hour. With a special measuring method - the so-called eddy covariance method - the concentration of air components can be continuously monitored. An international team led by Thomas Karl from the Institute for Atmospheric and Cryosphere Sciences at the University of Innsbruck has now used this data to study the chemistry of ozone, nitrogen monoxide and nitrogen dioxide in urban areas in detail. The high proportion of diesel vehicles in European cities leads to high concentrations of nitrogen monoxide. This reacts with ozone, producing nitrogen dioxide.
doctrine needs to be specified
This chemical cycle was mathematically described in Philip Leighton's first textbook on air pollution over 60 years ago. The relationship between the two processes has since been referred to as the Leighton relationship. Computer models of atmospheric chemistry use the Leighton relationship to minimize complexity by deriving the concentrations of ozone, nitric oxide, and nitrogen dioxide from the concentrations of the other two. In practice, this is used, for example, to derive the ozone concentration in areas polluted by nitrogen oxides.The data from the Innsbruck atmospheric researchers now show that when there are high nitrogen monoxide emissions, the simplified calculations made by Leighton lead to incorrect results. "In cities with high nitrogen monoxide emissions, this ratio is overestimated by up to 50 percent," warns Thomas Karl. “As a result, model calculations overestimate the concentration of ground-level ozone in urban areas. This is also reflected in the air quality forecasts.” This effect should not be neglected when modeling the lowest layer of the atmosphere, up to 200 meters above the ground.
Responsible for the effect investigated by the Innsbruck scientists are, in addition to the presence of high nitrogen monoxide emissions, the stronger turbulence in urban areas. The mixing of the gases combined with the relatively rapid chemical processes mean that more ozone is converted into nitrogen dioxide. The researchers' data also show that the direct emission of nitrogen dioxide from urban traffic is largely negligible in comparison. "It is important to note that environmental policy regulations do not refer to model calculations, but rather come into force depending on the concentrations of pollutants actually measured," emphasizes Thomas Karl."
Environmental policy regulations rely on direct measurements instead of model calculations - maybe, maybe not. This would need to be checked.
The University of Innsbruck explains that ozone is not directly measured on the ground-level, it is rather deduced from the levels of nitrogen oxides.
The deduction is based on models which have now been found to render wrong results, overestimating ground-level ozone by up to 50%.
"dr Christian Flatz
Public Relations Office at the
Long-term measurements in the city of Innsbruck show that the proportion of ground-level ozone in atmospheric models tends to be overestimated. As a consequence, a fundamental doctrine for air quality prognosis has to be reinterpreted for urban areas. The measurements by an international team led by atmospheric researcher Thomas Karl from the University of Innsbruck also show that direct nitrogen dioxide emissions are overestimated.
The 40 meter high measuring tower of the Innsbruck Atmospheric Observatory at the university crossing in the city of Innsbruck continuously supplies data on the composition of the atmosphere near the ground. 36,000 data points are recorded per hour. With a special measuring method - the so-called eddy covariance method - the concentration of air components can be continuously monitored. An international team led by Thomas Karl from the Institute for Atmospheric and Cryosphere Sciences at the University of Innsbruck has now used this data to study the chemistry of ozone, nitrogen monoxide and nitrogen dioxide in urban areas in detail. The high proportion of diesel vehicles in European cities leads to high concentrations of nitrogen monoxide. This reacts with ozone, producing nitrogen dioxide.
doctrine needs to be specified
This chemical cycle was mathematically described in Philip Leighton's first textbook on air pollution over 60 years ago. The relationship between the two processes has since been referred to as the Leighton relationship. Computer models of atmospheric chemistry use the Leighton relationship to minimize complexity by deriving the concentrations of ozone, nitric oxide, and nitrogen dioxide from the concentrations of the other two. In practice, this is used, for example, to derive the ozone concentration in areas polluted by nitrogen oxides.The data from the Innsbruck atmospheric researchers now show that when there are high nitrogen monoxide emissions, the simplified calculations made by Leighton lead to incorrect results. "In cities with high nitrogen monoxide emissions, this ratio is overestimated by up to 50 percent," warns Thomas Karl. “As a result, model calculations overestimate the concentration of ground-level ozone in urban areas. This is also reflected in the air quality forecasts.” This effect should not be neglected when modeling the lowest layer of the atmosphere, up to 200 meters above the ground.
Responsible for the effect investigated by the Innsbruck scientists are, in addition to the presence of high nitrogen monoxide emissions, the stronger turbulence in urban areas. The mixing of the gases combined with the relatively rapid chemical processes mean that more ozone is converted into nitrogen dioxide. The researchers' data also show that the direct emission of nitrogen dioxide from urban traffic is largely negligible in comparison. "It is important to note that environmental policy regulations do not refer to model calculations, but rather come into force depending on the concentrations of pollutants actually measured," emphasizes Thomas Karl."
Environmental policy regulations rely on direct measurements instead of model calculations - maybe, maybe not. This would need to be checked.
