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SUMMARY:Direct measurements of urban pollutant emissions - Eiko Nemitz\, C
 EH
DTSTART:20181203T141500Z
DTEND:20181203T151500Z
UID:TALK115504@talks.cam.ac.uk
CONTACT:Dr Olalekan Popoola
DESCRIPTION:Predictions of air quality and air pollution impacts typically
  rely on numerical atmospheric chemistry and transport models. The perform
 ance of such model is never better than the underlying estimates of the em
 issions. Diffuse sources such as represented by urban areas are usually es
 timated through bottom-up emission inventories\, where activity figures (e
 .g.: vehicle kilometres driven in each 1 km2 grid cell) are combined with 
 emission factors (e.g.: grams of NO2 emitted per vehicle kilometre driven)
 \, which are often derived under non-representative (laboratory) condition
 s. As a result emission inventories are subject to considerable uncertaint
 y.\nIndependent verification of such emission inventories is difficult and
  usually done indirectly by assessing how well the models reproduce measur
 ed concentrations using a given estimate of emissions. This relies on good
  model performance and an accurate characterisation of background concentr
 ations.\nInstead\, we have pioneered the use of micrometeorological flux m
 easurement techniques\, more commonly applied to measure the pollutant exc
 hange with vegetation\, to quantify directly the vertical flux above the c
 ity. For this we mount fast-response chemical sensors on city flux towers\
 ; depending on the measurement height such flux measurements integrate the
  emission from several km2.\nThis talk will introduce the concept and intr
 oduce examples of flux measurements of a range of pollutants (including gr
 eenhouse gases\, aerosols\, NH3\, VOCs\, CO\, O3\, …) from a number of c
 ities\, with focus on Edinburgh\, London and Beijing\, together with some 
 of the sometimes surprising results.
LOCATION:Pfizer Lecture Theatre\, Department of Chemistry
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