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

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dc.contributor.authorChambers, SDen_AU
dc.contributor.authorWilliams, AGen_AU
dc.contributor.authorZahorowski, Wen_AU
dc.contributor.authorGriffiths, ADen_AU
dc.contributor.authorCrawford, Jen_AU
dc.date.accessioned2012-05-01T01:56:55Zen_AU
dc.date.available2012-05-01T01:56:55Zen_AU
dc.date.issued2011-11-01en_AU
dc.date.statistics2012-05-01en_AU
dc.description.abstractTwo-point radon gradients provide a direct, unambiguous measure of near-surface atmospheric mixing. A 31-month data set of hourly radon measurements at 2 and 50 m is used to characterize the seasonality and diurnal variability of radon concentrations and gradients at a site near Sydney. Vertical differencing allows separation of remote (fetch-related) effects on measured radon concentrations from those due to diurnal variations in the strength and extent of vertical mixing. Diurnal composites, grouped according to the maximum nocturnal radon gradient (Delta C(max)), reveal strong connections between radon, wind, temperature and mixing depth on subdiurnal timescales. Comparison of the bulk Richardson Number (Ri(B)) and the turbulence kinetic energy (TKE) with the radon-derived bulk diffusivity (K(B)) helps to elucidate the relationship between thermal stability, turbulence intensity and the resultant mixing. On nights with large Delta C(max), K(B) and TKE levels are low and Ri(B) is well above the 'critical' value. Conversely, when Delta C(max) is small, K(B) and TKE levels are high and Ri(B) is near zero. For intermediate Delta C(max), however, Ri(B) remains small whereas TKE and K(B) both indicate significantly reduced mixing. The relationship between stability and turbulence is therefore non-linear, with even mildly stable conditions being sufficient to suppress mixing. © 2011, Wiley-Blackwell.en_AU
dc.identifier.citationChambers, S., Williams, A. G., Zahorowski, W., Griffiths, A., & Crawford, J. (2011). Separating remote fetch and local mixing influences on vertical radon measurements in the lower atmosphere. Tellus B: Chemical and Physical Meteorology, 63(5), 843-859. doi:10.1111/j.1600-0889.2011.00565.xen_AU
dc.identifier.govdoc4081en_AU
dc.identifier.issn0280-6509en_AU
dc.identifier.issue5en_AU
dc.identifier.journaltitleTellus B: Chemical and Physical Meteorologyen_AU
dc.identifier.pagination843-859en_AU
dc.identifier.urihttp://dx.doi.org/10.1111/j.1600-0889.2011.00565.xen_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/4200en_AU
dc.identifier.volume63en_AU
dc.language.isoenen_AU
dc.publisherWiley-Blackwellen_AU
dc.subjectRadonen_AU
dc.subjectAtmospheresen_AU
dc.subjectRadon 220en_AU
dc.subjectDaughter productsen_AU
dc.subjectDiffusionen_AU
dc.subjectRadon 222en_AU
dc.titleSeparating remote fetch and local mixing influences on vertical radon measurements in the lower atmosphereen_AU
dc.typeJournal Articleen_AU
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