Measurement of NOx and CO fluxes from a tall tower in Beijing

Squires, Freya Anne; Drysdale, William S.; Hamilton, Jacqueline; Lee, James L.; Vaughan, Adam Robert; Wild, Oliver; Mullinger, Neil ORCID: https://orcid.org/0000-0002-3148-6950; Nemitz, Eiko ORCID: https://orcid.org/0000-0002-1765-6298; Metzger, Stefan; Zhang, Qiang. 2017 Measurement of NOx and CO fluxes from a tall tower in Beijing. In: AGU Fall Meeting 2017, New Orleans, USA, 11-15 Dec 2017. (Unpublished)

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Abstract/Summary

China’s air quality problems are well publicised; in 2010, 1.2 million premature deaths were attributed to outdoor air pollution in China. One of the major air quality issues is high concentrations of nitrogen oxides (NOx). China is the largest NOx emitter, contributing an estimated 18 % to global NOx emissions. Beijing itself is reported to have NO2 concentrations 42 % higher than the annual national standard. Given the high levels of pollution, increased focus has been placed on improving emissions estimates which are typically developed using a ‘bottom-up’ approach where emissions are predicted from their sources. Emission inventories in China have large uncertainties and are rapidly changing with time in response to economic development, environmental regulation and new technologies. In fact, China is the largest contributor to the uncertainty in the source and the magnitude of air pollutants in air quality models. Recent studies have shown a discrepancy between NOx inventories and measured NOx emissions for UK cities, highlighting the limitations of bottom-up emissions inventories and the importance of accurate measurement data to improve the estimates. 5 Hz measurements of NOx and CO concentration were made as part of the Air Pollutants in Beijing (AIRPOLL-Beijing) project during two field campaigns in Nov-Dec 2016 and May-June 2017. Sampling took place from an inlet co-located with a sonic anemometer at 102 m on a meteorological tower in central Beijing. Analysis of the covariance between vertical wind speed and concentration enabled the calculation of emission flux, with an estimated footprint of between 2 – 5 km from the tower (which typically included some major ring roads and expressways). Fluxes were quantified using the continuous wavelet transformation (CWT) method, which enabled one minute resolved fluxes to be calculated. These data were compared to existing emissions estimates from the Multi-resolution Emission Inventory for China (MEIC). It is anticipated that this work will be used to evaluate the accuracy of emissions inventories for Beijing and to develop improved emissions estimates.

Item Type:	Publication - Conference Item (Paper)
UKCEH and CEH Sections/Science Areas:	Atmospheric Chemistry and Effects (Science Area 2017-)
NORA Subject Terms:	Atmospheric Sciences
Date made live:	23 May 2018 13:03 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/520017

Item Type:

Publication - Conference Item (Paper)

UKCEH and CEH Sections/Science Areas:

Atmospheric Chemistry and Effects (Science Area 2017-)

NORA Subject Terms:

Atmospheric Sciences

Date made live:

23 May 2018 13:03 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/520017