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Published in:
2021 | OriginalPaper | Chapter
Urban Atmospheric Composition Processes
Author : William Bloss
Published in: Air Pollution Sources, Statistics and Health Effects
Publisher: Springer US
Excerpt
Boundary layer
The lowermost layer of the atmosphere, in contact with the surface and well mixed. Extending from 100 to 200 m at night, up to 1–2 km during the day.
Mixing ratio
The fraction of the air which a given species comprises, typically parts per million (10
6), billion (10
9) or trillion (10
12), by volume.
NO x
The sum of nitric oxide (NO) and nitrogen dioxide (NO
2).
NO x limited
The ozone production regime in which VOCs are (relatively) plentiful, and ozone production is limited by the availability of NO
x.
Photostationary steady state
The rapid chemical/photochemical balance between a number of reactants, usually applied to NO, NO
2 and O
3.
PM 10
Suspended airborne particulate matter, with an aerodynamic diameter of 10 μm or less.
Primary pollutants
Those emitted directly to the atmosphere, typically from mechanical or combustion processes.
Secondary pollutants
Those formed within the atmosphere by chemical reactions.
Street canyon
The semi-isolated atmospheric compartment formed by adjacent rows of multi-story buildings.
Temperature inversion
An increase in temperature with increasing altitude, which usually isolates ground-level air from the overlying atmosphere, resulting in increased (primary) pollutant concentrations.
Transboundary pollution
The transport of long-lived chemical species, such as O
3 and CO, across national boundaries.
VOC
Volatile Organic Compound, one commonly found overwhelmingly in the gas phase.
VOC limited
The ozone production regime where NO
x is plentiful, and ozone production is limited by the availability of hydrocarbons.