Separating remote fetch and local mixing influences on vertical radon
                        measurements in the lower atmosphere

Chambers, Scott D.; Williams, Alastair G.; Zahorowski, W.; Griffiths, Alan D.

doi:10.1111/j.1600-0889.2011.00565.x

Cited by 90 publications

(92 citation statements)

References 52 publications

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“…The use of radon to characterise boundary layer mixing (Chambers et al, 2011) is likely to be especially useful for testing air quality models due to the challenges of modelling within the complex topography of coastal areas. The locations of all of the sites used in the MUMBA campaign are marked on the satellite view of the region shown in Fig.…”

Section: Measurement Sitesmentioning

confidence: 99%

The MUMBA campaign: measurements of urban, marine and biogenic air

Paton-Walsh

Guérette

Kubistin

et al. 2017

Earth Syst. Sci. Data

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Abstract. The Measurements of Urban, Marine and Biogenic Air (MUMBA) campaign took place in Wollongong, New South Wales (a small coastal city approximately 80 km south of Sydney, Australia) from 21 December 2012 to 15 February 2013. Like many Australian cities, Wollongong is surrounded by dense eucalyptus forest, so the urban airshed is heavily influenced by biogenic emissions. Instruments were deployed during MUMBA to measure the gaseous and aerosol composition of the atmosphere with the aim of providing a detailed characterisation of the complex environment of the ocean–forest–urban interface that could be used to test the skill of atmospheric models. The gases measured included ozone, oxides of nitrogen, carbon monoxide, carbon dioxide, methane and many of the most abundant volatile organic compounds. The aerosol characterisation included total particle counts above 3 nm, total cloud condensation nuclei counts, mass concentration, number concentration size distribution, aerosol chemical analyses and elemental analysis.The campaign captured varied meteorological conditions, including two extreme heat events, providing a potentially valuable test for models of future air quality in a warmer climate. There was also an episode when the site sampled clean marine air for many hours, providing a useful additional measure of the background concentrations of these trace gases within this poorly sampled region of the globe. In this paper we describe the campaign, the meteorology and the resulting observations of atmospheric composition in general terms in order to equip the reader with a sufficient understanding of the Wollongong regional influences to use the MUMBA datasets as a case study for testing a chemical transport model. The data are available from PANGAEA (http://doi.pangaea.de/10.1594/PANGAEA.871982).

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Section: Measurement Sitesmentioning

confidence: 99%

The MUMBA campaign: measurements of urban, marine and biogenic air

Paton-Walsh

Guérette

Kubistin

et al. 2017

Earth Syst. Sci. Data

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“…10). Overall, well-mixed conditions were typically associated with nocturnal wind speeds of 1.4Á 3.3 m s (2006) and Chambers et al (2011Chambers et al ( , 2015a, who each associated stable nocturnal conditions (including morning haze events) with wind speeds less than 1Á1.5 m s (1 .…”

Section: Meteorological Characterisation Of Radon-derived Stability Cmentioning

confidence: 99%

“…concentrations of the ubiquitous surface-emitted passive tracer radon (e.g. Allegrini et al, 1994;Duenas et al, 1996;Perrino, 2001Perrino, , 2012Avino et al, 2003;Galmarini, 2006;Sesana et al, 2006;Chambers et al, 2011Chambers et al, , 2015aChambers et al, , 2015bChambers et al, , 2016Wang et al, 2013;Williams et al, 2013;Kondo et al, 2014;Pitari et al, 2014;Omori and Nagahama, 2016). Radon-derived measures of atmospheric stability, based on accumulation/dilution patterns of radon near the surface, are rapidly gaining acceptance because they are better suited to the analysis of mixing-related changes in nocturnal urban air pollution concentrations than the more traditional techniques based on climatological or turbulence measurements.…”

Section: Radon-based Atmospheric Stability Classificationmentioning

confidence: 99%

See 1 more Smart Citation

Radon as a tracer of atmospheric influences on traffic-related air pollution in a small inland city

Williams¹,

Chambers²,

Conen³

et al. 2016

Tellus B: Chemical and Physical Meteorology

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A B S T R A C T One year of radon, benzene and carbon monoxide (CO) concentrations were analysed to characterise the combined influences of variations in traffic density and meteorological conditions on urban air quality in Bern, Switzerland. A recently developed radon-based stability categorisation technique was adapted to account for seasonal changes in day length and reduction in the local radon flux due to snow/ice cover and high soil moisture. Diurnal pollutant cycles were shown to result from an interplay between variations in surface emissions (traffic density), the depth of the nocturnal atmospheric mixing layer (dilution) and local horizontal advection of cleaner air from outside the central urban/industrial area of this small compact inland city. Substantial seasonal differences in the timing and duration of peak pollutant concentrations in the diurnal cycle were attributable to changes in day length and the switching to/from daylight-savings time in relation to traffic patterns. In summer, average peak benzene concentrations (0.62 ppb) occurred in the morning and remained above 0.5 ppb for 2 hours, whereas in winter average peak concentrations (0.85 ppb) occurred in the evening and remained above 0.5 ppb for 9 hours. Under stable conditions in winter, average peak benzene concentrations (1.1 ppb) were 120% higher than for well-mixed conditions (0.5 ppb). By comparison, summertime peak benzene concentrations increased by 53% from well-mixed (0.45 ppb) to stable nocturnal conditions (0.7 ppb). An idealised box model incorporating a simple advection term was used to derive a nocturnal mixing length scale based on radon, and then inverted to simulate diurnal benzene and CO emission variations at the city centre. This method effectively removes the influences of local horizontal advection and stability-related vertical dilution from the emissions signal, enabling a direct comparison with hourly traffic density. With the advection term calibrated appropriately, excellent results were obtained, with high regression coefficients in spring and summer for both benzene (r 2 Â0.90Á0.96) and CO (r 2 Â0.88Á0.98) in the two highest stability categories. Weaker regressions in winter likely indicate additional contributions from combustion sources unrelated to vehicular emissions. Average vehicular emissions during daylight hours were estimated to be around 0.503 (542) kg km (2 h (1 for benzene (CO) in the Bern city centre.

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“…The boundary layer is assumed to be well mixed at this time because vertical gradients are negligible compared with the nocturnal peak, e.g. 0.2 Bq m −3 between 2 and 50 m (Moses et al, 1960;Chambers et al, 2011). The first estimate of nightly average surface emissions (30 mBq m 2 s −1 ) is taken from Griffiths et al (2010), although we refine this later, as described in Sect.…”

Section: The Radon-based Equivalent Mixing Heightmentioning

confidence: 99%

Improved mixing height monitoring through a combination of lidar and radon measurements

et al. 2013

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Surface-based radon (<sup>222</sup>Rn) measurements can be combined with lidar backscatter to obtain a higher quality time series of mixing height within the planetary boundary layer (PBL) than is possible from lidar alone, and a more quantitative measure of mixing height than is possible from only radon. The reason why lidar measurements are improved is that there are times when lidar signals are ambiguous, and reliably attributing the mixing height to the correct aerosol layer presents a challenge. By combining lidar with a mixing length scale derived from a time series of radon concentration, automated and robust attribution is possible during the morning transition. <br><br> Radon measurements provide mixing information during the night, but concentrations also depend on the strength of surface emissions. After processing radon in combination with lidar, we obtain nightly measurements of radon emissions and are able to normalise the mixing length scale for changing emissions. After calibration with lidar, the radon-derived equivalent mixing height agrees with other measures of mixing on daily and hourly timescales and is a potential method for studying intermittent mixing in nocturnal boundary layers

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Separating remote fetch and local mixing influences on vertical radon measurements in the lower atmosphere

Cited by 90 publications

References 52 publications

The MUMBA campaign: measurements of urban, marine and biogenic air

The MUMBA campaign: measurements of urban, marine and biogenic air

Radon as a tracer of atmospheric influences on traffic-related air pollution in a small inland city

Improved mixing height monitoring through a combination of lidar and radon measurements

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