Characterizing Atmospheric Transport Pathways to Antarctica and the Remote Southern Ocean Using Radon-222

Chambers, Scott D.; Preunkert, Susanne; Weller, Rolf; Hong, Sang-Bum; Humphries, Ruhi S.; Tositti, Laura; Angot, Hélène; Legrand, Michel; Williams, Alastair G.; Griffiths, Alan D.; Crawford, Jagoda; Simmons, Jack B.; Choi, Taejin; Krummel, P. B.; Molloy, Suzie; Loh, Zoë; Galbally, Ian E.; Wilson, Stephen R.; Magand, Olivier; Sprovieri, Francesca; Pirrone, Nicola; Dommergue, Aurélien

doi:10.3389/feart.2018.00190

Cited by 41 publications

(38 citation statements)

References 107 publications

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“…Here we select radon levels below 200 mBq m −3 to reflect oceanic air. This threshold is double that commonly utilised at Cape Grim for identifying clean marine air [58,59] and four times higher than that of pristine oceanic air [60], but much less than the several thousand mBq m −3 observed in continental air. Note that the sampled marine air will have accumulated minor amounts of radon during the overland transport from the coast to the ANSTO monitoring site (approximately 3 km inland).…”

Section: Identifying Episodes Of Clean Marine Air At the Mumba Sitementioning

confidence: 71%

Composition of Clean Marine Air and Biogenic Influences on VOCs during the MUMBA Campaign

et al. 2019

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Volatile organic compounds (VOCs) are important precursors to the formation of ozone and fine particulate matter, the two pollutants of most concern in Sydney, Australia. Despite this importance, there are very few published measurements of ambient VOC concentrations in Australia. In this paper, we present mole fractions of several important VOCs measured during the campaign known as MUMBA (Measurements of Urban, Marine and Biogenic Air) in the Australian city of Wollongong (34°S). We particularly focus on measurements made during periods when clean marine air impacted the measurement site and on VOCs of biogenic origin. Typical unpolluted marine air mole fractions during austral summer 2012-2013 at latitude 34°S were established for CO2 (391.0 ± 0.6 ppm), CH4 (1760.1 ± 0.4 ppb), N2O (325.04 ± 0.08 ppb), CO (52.4 ± 1.7 ppb), O3 (20.5 ± 1.1 ppb), acetaldehyde (190 ± 40 ppt), acetone (260 ± 30 ppt), dimethyl sulphide (50 ± 10 ppt), benzene (20 ± 10 ppt), toluene (30 ± 20 ppt), C8H10 aromatics (23 ± 6 ppt) and C9H12 aromatics (36 ± 7 ppt). The MUMBA site was frequently influenced by VOCs of biogenic origin from a nearby strip of forested parkland to the east due to the dominant north-easterly afternoon sea breeze. VOCs from the more distant densely forested escarpment to the west also impacted the site, especially during two days of extreme heat and strong westerly winds. The relative amounts of different biogenic VOCs observed for these two biomes differed, with much larger increases of isoprene than of monoterpenes or methanol during the hot westerly winds from the escarpment than with cooler winds from the east. However, whether this was due to different vegetation types or was solely the result of the extreme temperatures is not entirely clear. We conclude that the clean marine air and biogenic signatures measured during the MUMBA campaign provide useful information about the typical abundance of several key VOCs and can be used to constrain chemical transport model simulations of the atmosphere in this poorly sampled region of the world.

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Section: Identifying Episodes Of Clean Marine Air At the Mumba Sitementioning

confidence: 71%

Composition of Clean Marine Air and Biogenic Influences on VOCs during the MUMBA Campaign

et al. 2019

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“…Its half-life of T 1/2 = 3.82 days is comparable to the air masses' transit time across the major continents. Outdoor radon monitoring serves also on earthquake forecasting, geological faults identifications or ore exploration, and environmental reprocessing in mining [4][5][6][7]. Some researchers have reported a positive correlation between outdoor radon concentration and radon exhalation rate from the ground [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Long-Term Measurements of Radon and Thoron Exhalation Rates from the Ground Using the Vertical Distributions of Their Activity Concentrations

Modibo

Tamakuma

Suzuki

et al. 2021

IJERPH

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A long-term measurement technique of radon exhalation rate was previously developed using a passive type radon and thoron discriminative monitor and a ventilated type accumulation chamber. In the present study, this technique was applied to evaluate the thoron exhalation rate as well, and long-term measurements of radon and thoron exhalation rates were conducted for four years in Gifu Prefecture. The ventilated type accumulation chamber (0.8 × 0.8 × 1.0 m3) with an open bottom was embedded 15 cm into the ground. The vertical distributions of radon and thoron activity concentrations from the ground were obtained using passive type radon-thoron discriminative monitors (RADUETs). The RADUETs were placed at 1, 3, 10, 30, and 80 cm above the ground inside the accumulation chamber. The measurements were conducted from autumn 2014 to autumn 2018. These long-term results were found to be in good agreement with the values obtained by another methodology. The radon exhalation rates from the ground showed a clearly seasonal variation. Similar to findings of previous studies, radon exhalation rates from summer to autumn were relatively higher than those from winter to spring. In contrast, thoron exhalation rates were not found to show seasonal variation.

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“…This nss-SO 4 production depends significantly on precursor concentrations and favourable meteorological conditions (Bianchi et al, 2016), while the resulting size distribution of nss-SO 4 aerosol is affected by the surface area concentration of other aerosols that can act as condensation sinks (O'Dowd and de Leeuw, 2007). In both the tropics and the Southern Ocean, cloud-based convective transport of air masses into the free troposphere has been shown to result in new particle formation (NPF) (Clarke et al, 1998;Williamson et al, 2019). The colder air temperatures of the free troposphere promote partitioning into the aerosol phase, while the in-cloud wet scavenging of CCN removes competing condensation sinks.…”

Section: Introductionmentioning

confidence: 99%

Marine productivity and synoptic meteorology drive summer-time variability in Southern Ocean aerosols

et al. 2020

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Abstract. Cloud–radiation interactions over the Southern Ocean are not well constrained in climate models, in part due to uncertainties in the sources, concentrations, and cloud-forming potential of aerosol in this region. To date, most studies in this region have reported measurements from fixed terrestrial stations or a limited set of instrumentation and often present findings as broad seasonal or latitudinal trends. Here, we present an extensive set of aerosol and meteorological observations obtained during an austral summer cruise across the full width of the Southern Ocean south of Australia. Three episodes of continental-influenced air masses were identified, including an apparent transition between the Ferrel atmospheric cell and the polar cell at approximately 64∘ S, and accompanied by the highest median cloud condensation nuclei (CCN) concentrations, at 252 cm−3. During the other two episodes, synoptic-scale weather patterns diverted air masses across distances greater than 1000 km from the Australian and Antarctic coastlines, respectively, indicating that a large proportion of the Southern Ocean may be periodically influenced by continental air masses. In all three cases, a highly cloud-active accumulation mode dominated the size distribution, with up to 93 % of the total number concentration activating as CCN. Frequent cyclonic weather conditions were observed at high latitudes and the associated strong wind speeds led to predictions of high concentrations of sea spray aerosol. However, these modelled concentrations were not achieved due to increased aerosol scavenging rates from precipitation and convective transport into the free troposphere, which decoupled the air mass from the sea spray flux at the ocean surface. CCN concentrations were more strongly impacted by high concentrations of large-diameter Aitken mode aerosol in air masses which passed over regions of elevated marine biological productivity, potentially contributing up to 56 % of the cloud condensation nuclei concentration. Weather systems were vital for aerosol growth in biologically influenced air masses and in their absence ultrafine aerosol diameters were less than 30 nm. These results demonstrate that air mass meteorological history must be considered when modelling sea spray concentrations and highlight the potential importance of sub-grid-scale variability when modelling atmospheric conditions in the remote Southern Ocean.

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Characterizing Atmospheric Transport Pathways to Antarctica and the Remote Southern Ocean Using Radon-222

Cited by 41 publications

References 107 publications

Composition of Clean Marine Air and Biogenic Influences on VOCs during the MUMBA Campaign

Composition of Clean Marine Air and Biogenic Influences on VOCs during the MUMBA Campaign

Long-Term Measurements of Radon and Thoron Exhalation Rates from the Ground Using the Vertical Distributions of Their Activity Concentrations

Marine productivity and synoptic meteorology drive summer-time variability in Southern Ocean aerosols

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