ANSTO :: Browsing by Author "Chambers, SD"

Browsing by Author "Chambers, SD"

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20 year Australian Antarctic strategic plan
(Australian Government Department of the Environment and Energy, 2014-07) Williams, AG; Chambers, SD; Smith, AM
Aerosol iron solubility: comparison between the Australian subtropics and Southern ocean
(Bureau of Meteorology and CSIRO Oceans and Atmosphere Flagship, 2014-11) Winton, H; Edwards, R; Bowie, A; Chambers, SD; Keywood, MD; Werczynski, S; Williams, AG
Past changes in the atmospheric deposition of soluble, or bioavailable, trace metals to high nutrient low chlorophyll (HNLC) and nitrogen replete tropical waters have been shown to modulate primary production, atmospheric CO2, and global climate. The deposition of soluble trace metals can also trigger toxic algal blooms, which impact Australia’s fisheries and coral reefs. An understanding of the sources (e.g. mineral dust and biomass emissions) and geochemistry of soluble trace metals in atmospheric aerosols is critical for determining the impact of trace metal deposition on ocean fertility in the past and the future. However, to date no trace metal solubility data exists for biomass emissions from Australian fires and there are very few estimates of soluble trace metal aerosols entering the Southern Ocean. Trace metal clean aerosols were collected during the early‐late dry season experiment at Gunn Point, Northern Territory to investigate the trace metal aerosol solubility associated with biomass burning. Previous studies have suggested that mineral dust is the dominant source of trace metal aerosol. However, mineral dust is relatively insoluble and a significant fraction of soluble trace metals in the atmosphere could originate from biomass burning rather than mineral dust. Here we use the combination of soluble aerosol chemistry, back trajectories and diurnal and advective radon components to identify trace metal source regions throughout the campaign duration. We compare aerosol iron solubility at Gunn Point in the subtropics, where biomass burning can dominate the aerosol load in the dry season, to iron solubility in baseline air at Cape Grim which is representative of the Southern Hemisphere background. In doing this we highlight the importance of aerosol source at different latitudes for the solubility and bioavailability of trace metals.
Analysis of a decade of Asian outflow of PM10 and TSP to Gosan, Korea: also incorporating Radon-222
(Elsevier B.V., 2015-05) Crawford, J; Chambers, SD; Kang, CH; Griffiths, AD; Kim, WH
Ten years of aerosol and Radon–222 (radon) data from Gosan, Korea, were analyzed. Seasonal cycles were strongly linked to changes in fetch and time of year. We estimated that 7.21 t/m y of PMio aerosol pass Gosan in the atmospheric boundary layer, increasing annually by 0.3 t/m y. Contributions to aerosol loading were characterized by fetch: South China, North China, Korea and Japan. While the highest, and most variable, contributions typically originated from South China, these air masses contributed to only 6% of the overall dataset. PM10 distributions were broader from South and North China than for Korea or Japan, reflecting differences in natural/anthropogenic soil sources, and number/distribution of large point sources. Employing radon to select air masses more representative of targeted fetch regions typically resulted in greater reported pollutant concentrations and rates of change over the decade. Estimated rates of PM10 increase from North China and Korea over the decade were 1.4 and 0.9 μg/m3 y, respectively. Total suspended particulate (TSP) elemental analysis indicated that the (non–sea–salt) nss–SO42− content of aerosols has been gradually increasing over the past decade and more recently an increase in NO3− was seen. However, on average, rates of increase in nss–SO42− have reduced since 2007, which were higher in South than North China. © 2020 Elsevier B.V.
ANSTO radon measurements at Cape Grim and other global atmospheric monitoring sites
(University of New South Wales and Australian Nuclear Science and Technology Organisation, 2015-07-09) Williams, AG; Chambers, SD
Not supplied to the ANSTO Library.
Application for 222Rn in atmospheric research
(Australian Nuclear Science and Technology Organisation, 2012-10-16) Chambers, SD; Williams, AG; Zahorowski, W; Griffiths, AD
Radon-222 (radon) is a relatively short-lived (half-life 3.82 d), naturally occurring, radioactive gas, with a relatively consistent and well-defined terrestrial flux, and almost negligible oceanic flux. Being a noble, poorly-soluble gas that does not accumulate in the atmosphere, it is an ideal tracer of recent (<2-3 weeks) air mass contact with ice-free terrestrial regions. In conjunction with air mass back trajectory analysis, radon is thus a useful tool with which to perform fetch analyses for observed pollution events. Since radon’s half-life is much greater than the turbulent timescale in the atmospheric boundary layer (~1 hour), it can be considered a conservative tracer in such situations. Consequently, radon profiles or gradient measurements in the lower atmosphere also provide valuable insight into vertical mixing processes under a range of atmospheric conditions. This presentation will provide an overview of ANSTO’s radon measurement capabilities (including: standalone detectors, tall-tower gradient measurements, aircraft profile measurements and flux chambers), with recent examples of their recent application. Radon’s physical characteristics also make it ideal for the evaluation of transport and mixing schemes of weather, climate or chemical models. This presentation will also showcase a radon flux map of Australia, developed at ANSTO to improve the radon source function employed in regional models.
Assessing the impact of atmospheric stability on locally and remotely sourced aerosols at Richmond, Australia, using Radon-222
(Elsevier, 2015-12-13) Crawford, J; Chambers, SD; Cohen, DD; Williams, AG; Griffiths, AD; Stelcer, E
A flexible radon-based scheme for the classification of nocturnal stability regimes was used for the interpretation of daily-integrated PM2.5 aerosol observations collected at Richmond, Australia, between 2007 and 2011. Source fingerprint concentrations for the dominant locally and remotely sourced aerosols were analysed by nocturnal radon stability category to characterise the influences of day-to-day changes in daily integrated atmospheric mixing. The fingerprints analysed included: smoke, vehicle exhaust, secondary sulfate and aged industrial sulfur. The largest and most consistent stability influences were observed on the locally sourced pollutants. Based on a 5-year composite, daily integrated concentrations of smoke were almost a factor of 7 higher when nocturnal conditions were classed as “stable” than when they were “near neutral”. For vehicle emissions a factor of 4 was seen. However, when the winter months were considered in isolation, it was found that these factors increased to 11.5 (smoke) and 5.5 (vehicle emissions) for daily average concentrations. The changes in concentration of the remotely sourced pollutants with atmospheric stability were comparatively small and less consistent, probably as a result of the nocturnal inversion frequently isolating near-surface observations from non-local sources at night. A similar classification was performed using the commonly-adopted Pasquill–Gifford (PG) stability typing technique based on meteorological parameters. While concentrations of fingerprints associated with locally-sourced pollutants were also shown to be positively correlated with atmospheric stability using the PG classification, this technique was found to underestimate peak pollutant concentrations under stable atmospheric conditions by almost a factor of 2. © 2015, Elsevier Ltd.
Atmospheric stability effects on potential radiological releases at a nuclear research facility in Romania: characterising the atmospheric mixing state
(Elsevier, 2016-04-01) Chambers, SD; Galeriu, D; Williams, AG; Melintescu, A; Griffiths, AD; Crawford, J; Dyer, LL; Duma, M; Zorila, B
A radon-based nocturnal stability classification scheme is developed for a flat inland site near Bucharest, Romania, characterised by significant local surface roughness heterogeneity, and compared with traditional meteorologically-based techniques. Eight months of hourly meteorological and atmospheric radon observations from a 60 m tower at the IFIN-HH nuclear research facility are analysed. Heterogeneous surface roughness conditions in the 1 km radius exclusion zone around the site hinder accurate characterisation of nocturnal atmospheric mixing conditions using conventional meteorological techniques, so a radon-based scheme is trialled. When the nocturnal boundary layer is very stable, the Pasquill–Gifford “radiation” scheme overestimates the atmosphere's capacity to dilute pollutants with near-surface sources (such as tritiated water vapour) by 20% compared to the radon-based scheme. Under these conditions, near-surface wind speeds drop well below 1 m s−1 and nocturnal mixing depths vary from ∼25 m to less than 10 m above ground level (a.g.l.). Combining nocturnal radon with daytime ceilometer data, we were able to reconstruct the full diurnal cycle of mixing depths. Average daytime mixing depths at this flat inland site range from 1200 to 1800 m a.g.l. in summer, and 500–900 m a.g.l. in winter. Using tower observations to constrain the nocturnal radon-derived effective mixing depth, we were able to estimate the seasonal range in the Bucharest regional radon flux as: 12 mBq m−2 s−1 in winter to 14 mBq m−2 s−1 in summer. © 2016, Elsevier Ltd.
Atmospheric transport and chemistry of trace gases in LMDz5B
(Copernicus Publications, 2015-02-03) Locatelli, R; Bousquet, P; Hourdin, F; Saunois, M; Cozic, A; Couvreux, F; Grandpeix, JY; Lefebvre, MP; Rio, C; Bergamaschi, P; Chambers, SD; Karstens, U; Kazan, V; van der Laan, S; Meijer, HAJ; Moncrieff, J; Ramonet, M; Scheeren, HA; Schlosser, C; Schmidt, M; Vermeulen, AT; Williams, AG
Representation of atmospheric transport is a major source of error in the estimation of greenhouse gas sources and sinks by inverse modelling. Here we assess the impact on trace gas mole fractions of the new physical parameterizations recently implemented in the atmospheric global climate model LMDz to improve vertical diffusion, mesoscale mixing by thermal plumes in the planetary boundary layer (PBL), and deep convection in the troposphere. At the same time, the horizontal and vertical resolution of the model used in the inverse system has been increased. The aim of this paper is to evaluate the impact of these developments on the representation of trace gas transport and chemistry, and to anticipate the implications for inversions of greenhouse gas emissions using such an updated model. © Author(s, 2015.
Background level of atmospheric radon-222 concentrations at Gosan Station, Jeju Island, Korea in 2011
(Korea Science, 2014-04-20) Kim, WH; Ko, HJ; Hu, CG; Lee, HY; Lee, CK; Chambers, SD; Williams, AG; Kang, CH
Real-time monitoring of hourly atmospheric radon (Rn-222) concentration was performed throughout 2011 at Gosan station, Jeju Island, one of the least polluted regions in Korea, in order to characterize the background levels, and temporal variations on diurnal to seasonal time-scales. The annual mean radon concentration for 2011 was mBq , and the seasonal cycle was characterized by a broad winter maximum, and narrow summer minimum. Mean monthly radon concentrations, in descending order of magnitude, were Oct > Sep > Feb > Nov > Jan > Dec > Mar > Aug > Apr > Jun > May > Jul. The maximum monthly mean value (3595 mBq , October), exceeded the minimum value (1243 mBq , July), by almost a factor of three. Diurnal composite hourly concentrations increased throughout the night to reach their maximum (2956 mBq ) at around 7 a.m., after which they decreased to their minimum value (2259 mBq ) at around 3 p.m. Back trajectory analyses indicated that the highest radon events typically exhibited long-term continental fetch over Asia before arriving at Jeju. In contrast, low radon events were generally correlated with air mass fetch over the North Pacific Ocean. Radon concentrations typical of predominantly continental, and predominantly oceanic fetch, differed by a factor of 3.8. (C) KISTI. All Rights Reserved.
Baseline characterisation of source contributions to daily-integrated PM2.5 observations at Cape Grim using Radon-222
(Elsevier, 2018-08-20) Crawford, J; Chambers, SD; Cohen, DD; Williams, AG; Atanacio, AJ
We discuss 15 years (2000–2015) of daily-integrated PM2.5 samples from the Cape Grim Station. Ion beam analysis and positive matrix factorisation are used to identify six source-type fingerprints: fresh sea salt (57%); secondary sulfate (14%); smoke (13%); aged sea salt (12%); soil dust (2.4%); and industrial metals (1.5%). An existing hourly radon-only baseline selection technique is modified for use with the daily-integrated observations. Results were not significantly different for days on which >20 hours were below the baseline radon threshold compared with days when all 24 hours satisfied the baseline criteria. This relaxed daily baseline criteria increased the number of samples for analysis by almost a factor of two. Two radon baseline thresholds were tested: historic (100 mBq m−3), and revised (50 mBq m−3). Median aerosol concentrations were similar for both radon thresholds, but maximum values were higher for the 100 mBq m−3 threshold. Back trajectories indicated more interaction with southern Australia and the Antarctic coastline for air masses selected with the 100 mBq m−3 threshold. Radon-only baseline selection using the 50 mBq m−3 threshold was more selective of minimal terrestrial influence than a similar recent study using wind direction and back trajectories. The ratio of concentrations between terrestrial and baseline days for the primary sources soil, smoke and industrial metals was 3.4, 2.6, and 5.5, respectively. Seasonal cycles of soil dust had a summer maximum and winter minimum. Seasonal cycles of smoke were of similar amplitude for terrestrial and baseline events, but of completely different shape: peaking in autumn and spring for terrestrial events, compared to summer for baseline conditions. Seasonal cycles of industrial metals had a summer maximum and winter minimum. A significant fraction of the Cape Grim baseline smoke and industrial metal contributions appeared to be derived from long-term transport (>3 weeks since last terrestrial influence). Crown Copyright © 2018 Published by Elsevier Ltd.
Benchmarks for chemical transport models based on radon-derived stability assessment of urban air pollution
(University of New South Wales and Australian Nuclear Science and Technology Organisation, 2015-07-09) Chambers, SD; Williams, AG
Not provided to the ANSTO Library.
Bulk mixing and decoupling of the nocturnal boundary layer characterised using a ubiquitous natural tracer
(Springer, 2013-12-01) Williams, AG; Chambers, SD; Griffiths, AD
Vertical mixing of the nocturnal stable boundary layer (SBL) over a complex land surface is investigated for a range of stabilities, using a decoupling index () based on the 2-50 m bulk gradient of the ubiquitous natural trace gas radon-222. The relationship between and the bulk Richardson number () exhibits three broad regions: (1) a well-mixed region () in weakly stable conditions (); (2) a steeply increasing region () for "transitional" stabilities (); and (3) a decoupled region (-1.0) in very stable conditions (). exhibits a large variability within individual bins, however, due to a range of competing processes influencing bulk mixing under different conditions. To explore these processes in - space, we perform a bivariate analysis of the bulk thermodynamic gradients, various indicators of external influences, and key turbulence quantities at 10 and 50 m. Strong and consistent patterns are found, and five distinct regions in - space are identified and associated with archetypal stable boundary-layer regimes. Results demonstrate that the introduction of a scalar decoupling index yields valuable information about turbulent mixing in the SBL that cannot be gained directly from a single bulk thermodynamic stability parameter. A significant part of the high variability observed in turbulence statistics during very stable conditions is attributable to changes in the degree of decoupling of the SBL from the residual layer above. When examined in - space, it is seen that very different turbulence regimes can occur for the same value of , depending on the particular combination of values for the bulk temperature gradient and wind shear, together with external factors. Extremely low turbulent variances and fluxes are found at 50 m height when and (fully decoupled). These "quiescent" cases tend to occur when geostrophic forcing is very weak and subsidence is present, but are not associated with the largest bulk temperature gradients. Humidity and net radiation data indicate the presence of low cloud, patchy fog or dew, any of which may aid decoupling in these cases by preventing temperature gradients from increasing sufficiently to favour gravity wave activity. The largest temperature gradients in our dataset are actually associated with smaller values of the decoupling index (), indicating the presence of mixing. Strong evidence is seen from enhanced turbulence levels, fluxes and submeso activity at 50 m, as well as high temperature variances and heat flux intermittencies at 10 m, suggesting this region of the - distribution can be identified as a top-down mixing regime. This may indicate an important role for gravity waves and other wave-like phenomena in providing the energy required for sporadic mixing at this complex terrain site. © 2013, Springer.
Characterisation of mixing processes in the lower atmosphere using Rn-222 and climate-sensitive gases
(Australian Nuclear Science and Technology Organisation, 2007-08) Schelander, P; Griffiths, AD; Williams, AG; Chambers, SD; Zahorowski, W
Characterising diurnal & synoptic timescale changes in urban air quality using Radon-222
(Europenan Geosciences Union, 2020-05-01) Chambers, SD; Kikaj, D; Podstawczyńska, A; Williams, AG; Crawford, J; Griffiths, AD
Urban air quality is strongly influenced by the atmosphere’s ability to disperse primary emissions and opportunities for secondary pollution formation. In mid- to high-latitude regions that experience enduring winter snow cover or soil freezing, regional subsidence and stagnation associated with persistent anti-cyclonic conditions such as the “Siberian High” can lead to “cold pool” or “persistent inversion” events. These events can result in life-threatening pollution episodes that last for weeks. While often associated with complex topography [1,2], persistent inversion events can also influence the air quality of urban centres in flat, inland regions [3]. This presentation will describe a recently-developed radon-based technique for identifying and characterising synoptic-timescale persistent inversion events, which is proving to be a simple and economical alternative to contemporary meteorological approaches that require regular sonde profiles [1]. Furthermore, key assumptions of the radon-based technique to characterise diurnaltimescale changes in the atmospheric mixing state described by Chambers et al. [4] are violated during persistent inversion conditions. Here we demonstrate how atmospheric class-typing, through successive application of radon-based techniques for identifying synoptic- and diurnaltimescale changes in the atmospheric mixing state, improves understanding of atmospheric controls on urban air quality in non-summer months across the full diurnal cycle. This knowledge translates directly to statistically-robust techniques for assessing public exposure to pollution, and for evaluating the efficacy of pollution mitigation measures. Lastly, we show how atmospheric class-typing can be used to enhance the evaluation of chemical transport models. © Author(s) 2020
Characterising terrestrial influences on Antarctic air masses using Radon-222 measurements at King George Island
(European Geosciences Union, 2014-09-18) Chambers, SD; Hong, SB; Williams, AG; Crawford, J; Griffiths, AD; Park, SJ
We report on one year of high-precision direct hourly radon observations at King Sejong Station (King George Island) beginning in February 2013. Findings are compared with historic and ongoing radon measurements from other Antarctic sites. Monthly median concentrations reduced from 72 mBq m−3 in late-summer to 44 mBq m−3 in late winter and early spring. Monthly 10th percentiles, ranging from 29 to 49 mBq m−3, were typical of oceanic baseline values. Diurnal cycles were rarely evident and local influences were minor, consistent with regional radon flux estimates one tenth of the global average for ice-free land. The predominant fetch region for terrestrially influenced air masses was South America (47–53° S), with minor influences also attributed to aged Australian air masses and local sources. Plume dilution factors of 2.8–4.0 were estimated for the most terrestrially influenced (South American) air masses, and a seasonal cycle in terrestrial influence on tropospheric air descending at the pole was identified and characterised. © Author(s) 2014
The citical role of observations in developing numerical representations of ice nucleating particles for southern ocean mixed phased clouds
(American Meterological Society, 2020-01-31) McCluskey, CS; DeMott, PJ; Hill, TCJ; Kreidenweis, SM; Ovadnevaite, J; Rinaldi, M; Atkinson, J; Belosi, F; Ceburnis, D; Marullo, S; Lohmann, U; Kanji, ZA; O'Dowd, C; Humphries, R; Rauker, AM; Moreau, S; Strutton, PG; Chambers, SD; Williams, AG; McRobert, I; Ward, J; Keywood, MD; Harnwell, J; Pronsonby, W; Loh, Z; Krummell, P; Protat, A; Gettelman, A; Bardeen, CG; Twohy, CH; MA, PL; Burrows, SM
The abundance of supercooled liquid clouds over the remote Southern Ocean (SO) region challenges the aerosol-cloud microphysical interactions that are currently represented in global climate models. In particular, most global climate models simulate SO clouds that are over-glaciated compared to satellite observations, leading to large radiative biases. Primary ice formation initiated by atmospheric ice nucleating particles (INPs) is a critical process in cloud glaciation and is augmented by additional processes, such as secondary ice production. Due to extremely high winds and large distances from land, the INP sources are likely dominated by locally produced sea spray aerosol (SSA) and long-range transported terrestrial aerosol (e.g., dust and pollution). However, a dearth of aerosol and INP observations in the remote SO have limited our ability to advance numerical representations of freezing processes until recent years. In this study, we demonstrate ways in which recent INP observations have improved our understanding of SO INP populations and how modeling studies can aid in developing hypotheses that can be tested by future observational studies. Coastal and ship observations were used to 1) characterize remote INP populations and 2) develop and test numerical representations of INPs relevant for remote oceanic regions. These observations revealed that INPs associated with SSA are up to a factor of 1000 less ice nucleation active compared to mineral dust. Extremely low INP concentrations observed over the SO support the prevalence of supercooled liquid clouds known to dominate the SO region. In a series of nudged simulations with the Community Earth System Model, Versions 1 and 2, we demonstrated that observed INP number concentrations in the marine boundary layer are successfully predicted using an approach that considers only SSA and dust INPs. This predictive tool was further used to estimate INP populations at higher altitudes over the SO study region, revealing that while SSA dominates the INP population below 3-5 km, mineral dust INPs may be critical for INP populations present above 5 km. Finally, an evaluation of model-estimated INPs present at higher altitudes using recent airborne measurements of INPs from the 2018 Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study will be presented.
Composition of clean marine air and biogenic influences on VOCs during the MUMBA campaign
(MDPI AG, 2019-07-10) Guérette, ÉA; Paton-Walsh, C; Galbally, IE; Molloy, SB; Lawson, S; Kubistin, D; Buchholz, R; Griffith, DWT; Langenfelds, RL; Krummel, PB; Loh, Z; Chambers, SD; Griffiths, AD; Keywood, MD; Selleck, PW; Dorminick, D; Humphries, R; Wilson, SR
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. © 2019 The Authors
Comprehensive aerosol and gas data set from the Sydney Particle Study
(Copernicus Publications, 2019-12-02) Keywood, MD; Selleck, PW; Reisen, F; Cohen, DD; Chambers, SD; Cheng, M; Cope, M; Crumeyrolle, S; Dunne, E; Emmerson, K; Fedele, R; Galbally, IE; Gillett, R; Griffiths, AD; Guerette, EA; Harnwell, J; Humphries, R; Lawson, S; Miljevic, B; Molloy, SB; Powell, J; Simmons, J; Ristovksi, Z; Ward, J
The Sydney Particle Study involved the comprehensive measurement of meteorology, particles and gases at a location in western Sydney during February–March 2011 and April–May 2012. The aim of this study was to increase scientific understanding of particle formation and transformations in the Sydney airshed. In this paper we describe the methods used to collect and analyse particle and gaseous samples, as well as the methods employed for the continuous measurement of particle concentrations, particle microphysical properties, and gaseous concentrations. This paper also provides a description of the data collected and is a metadata record for the data sets published in Keywood et al. (2016a, https://doi.org/10.4225/08/57903B83D6A5D) and Keywood et al. (2016b, https://doi.org/10.4225/08/5791B5528BD63). © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 Licence.
Concentration variability of atmospheric radon and gaseous pollutants at background area of Korea between 2017 and 2018
(Korea Institute of Science and Technology Information, 2022-02-25) Kim, WH; Yang, HS; Bu, JO; Kang, CH; Song, JM; Chambers, SD
The concentrations of radon in the atmosphere were measured at the Gosan site of Jeju Island during 2017-2018, in order to investigate the time-series variation characteristics and the dependency of airflow transport pathways. The mean 222Rn concentration was 2,480 mBq m-3, and its monthly concentration in November was 3,262 mBq m-3, more than twice as that in July (1,459 mBq m-3). The diurnal radon concentrations increased throughout the nighttime to the maximum (2,862 mBq m-3) at around 7 a.m., then gradually decreased throughout the daytime by the minimum (1,997 mBq m-3) at around 3 p.m. The seasonal and monthly variations of CO, NO2, O3 showed a roughly similar pattern to that of radon for the same period, as high in winter and low in summer. The cluster back trajectory analysis described that about 60 % of overall airflow pathways was influenced by the airflow from China. The concentrations of radon and gaseous pollutants were relatively high as the airflow was influenced by China continent, but comparatively much lower as influenced by the northern Pacific Ocean. © The Authors - open access article distributed under the terms of the Creative Commons Attribution Non-Commercial Licence.
Constraining annual and seasonal radon-222 flux density from the Southern Ocean using radon-222 concentrations in the boundary layer at Cape Grim
(Taylor & Francis Group, 2013-02-14) Zahorowski, W; Griffiths, AD; Chambers, SD; Williams, AG; Law, RM; Crawford, J; Werczynski, S
Radon concentrations measured between 2001 and 2008 in marine air at Cape Grim, a baseline site in northwestern Tasmania, are used to constrain the radon flux density from the Southern Ocean. A method is described for selecting hourly radon concentrations that are least perturbed by land emissions and dilution by the free troposphere. The distribution of subsequent radon flux density estimates is representative of a large area of the Southern Ocean, an important fetch region for Southern Hemisphere climate and air pollution studies. The annual mean flux density (0.27 mBq m 2 s 1) compares well with the mean of the limited number of spot measurements previously conducted in the Southern Ocean (0.24 mBq m 2 s 1), and to some spot measurements made in other oceanic regions. However, a number of spot measurements in other oceanic regions, as well as most oceanic radon flux density values assumed for modelling studies and intercomparisons, are considerably lower than the mean reported here. The reported radon flux varies with seasons and, in summer, with latitude. It also shows a quadratic dependence on wind speed and significant wave height, as postulated and measured by others, which seems to support our assumption that the selected least perturbed radon concentrations were in equilibrium with the oceanic radon source. By comparing the least perturbed radon observations in 2002 2003 with corresponding ‘TransCom’ model intercomparison results, the best agreement is found when assuming a normally distributed radon flux density with s 0.075 mBq m 2 s 1. © 2013, W. Zahorowski et al.

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