Sylvester Werczynski

Australian Nuclear Science and Technology Organisation

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Scott Chambers

Australian Nuclear Science and Technology Organisation

Alastair G. Williams

Australian Nuclear Science and Technology Organisation

W. Zahorowski

Australian Nuclear Science and Technology Organisation

Alan D. Griffiths

Australian Nuclear Science and Technology Organisation

A. Element

Commonwealth Scientific and Industrial Research Organisation

James Harnwell

CSIRO Oceans and Atmosphere

Brad Atkinson

Bureau of Meteorology

Peter F. Nelson

Macquarie University

A. L. Morrison

Macquarie University

Grant C. Edwards

Macquarie University

Cooperative Institutions

University of Wollongong

Australian Nuclear Science and Technology Organisation

CSIRO Oceans and Atmosphere

Commonwealth Scientific and Industrial Research Organisation

Centre National de la Recherche Scientifique

Commissariat à l'Énergie Atomique et aux Énergies Alternatives

Laboratoire des Sciences du Climat et de l'Environnement

Université Paris-Saclay

Queensland University of Technology

Université de Versailles Saint-Quentin-en-Yvelines

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Estimating the near-surface daily fine aerosol load using hourly Radon-222 observations

Atmospheric Pollution Research (2012)

Jagoda Crawford W. Zahorowski David D. Cohen Scott Chambers Eduard Stelcer

We investigate the extent to which hourly radon observations can be used to estimate daily PM2.5 loading near the ground. We formulate, test and apply a model that expresses the mean daily PM2.5 load as a linear combination of observed radon concentrations and differences on a given day. The model was developed using two consecutive years of observations (2007–2008) at four sites near Sydney, Australia, instrumented with aerosol samplers and radon detectors. Model performance was subsequently evaluated against observations in 2009. After successfully reproducing mean daily radon concentrations (r2≥0.98), we used the model to estimate daily PM2.5 mass, as well as that of selected elements (Si, K, Fe, Zn, H, S and Black Carbon). When parameterizing the model for elemental mass estimates the highest r2 values were generally obtained for H, BC, K and Si. Separating results by season, the r2 values for K and BC were higher in winter for all sites, a period of time where higher concentrations of these elements are seen and a rapid estimation tool would be of particular benefit. The best overall results were obtained in winter for H and BC [r2 = 0.50, 0.68, 0.70, 0.63 (H) and 0.57, 0.57, 0.78, 0.44 (BC)], respectively for Warrawong, Lucas Heights, Richmond and Muswellbrook. Evaluation of model PM2.5 estimates was most successful for days with typical aerosol loads; loads were usually underestimated for, the less frequent, high–to–extreme pollution days. The best elemental results were obtained for BC at Richmond in winter (r2 = 0.68). However, for Warrawong and Lucas Heights r2 values increased from 0.26 to 0.60, and from 0.33 to 0.73, respectively, when several particularly high concentration events were excluded from the analysis. The model performed best at Richmond, an inland site with relatively flat terrain. However, model parameters need to be evaluated for each site.

Mass concentration (chemistry)

10.5094/apr.2013.001

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Citations (10)

Supplementary material to "Biomass burning emissions in north Australia during the early dry season: an overview of the 2014 SAFIRED campaign"

Marc Mallet Maximilien Desservettaz Branka Miljevic Anđelija Milić Zoran Ristovski

Dry season

10.5194/acp-2016-866-supplement

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Citations (0)

A map of radon flux at the Australian land surface

Atmospheric chemistry and physics (2010)

Alan D. Griffiths W. Zahorowski A. Element Sylvester Werczynski

Abstract. A time-dependent map of radon-222 flux density at the Australian land surface has been constructed with a spatial resolution of 0.05° and temporal resolution of one month. Radon flux density was calculated from a simple model utilising data from national gamma-ray aerial surveys; modelled soil moisture, available from 1900 in near real-time; and maps of soil properties. The model was calibrated against a data set of accumulation chamber measurements, thereby constraining it with experimental data. A notable application of the map is in atmospheric mixing and transport studies which use radon as a tracer, where it is a clear improvement on the common assumption of uniform radon flux density.

TRACER

10.5194/acp-10-8969-2010

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Citations (84)

Improved estimation of total boundary layer radon for budget studies and regional integrations

EGU General Assembly Conference Abstracts (2010)

Alastair G. Williams W. Zahorowski Scott Chambers A. Element Sylvester Werczynski

Estimation of the total amount of the natural radioactive tracer radon-222 (radon) in a vertical column through the troposphere is a critical step in the process of calculating regionally integrated emissions of important greenhouse gases using radon-calibrated budget techniques. As continuous long-term radon time series used for such calculations are typically gathered at sites located at or near the surface, a rigorous column radon estimate would require knowledge of the vertical distribution of radon through the atmospheric boundary layer (ABL). The most frequent approach to addressing this issue is to assume a uniform radon profile within the ABL, and no radon in the free atmosphere above. This study aims at refining these traditional assumptions by presenting vertical integrations of high-resolution radon profiles, gathered using a motorised glider in and above daytime boundary layers over rural inland Australia under a range of stability and cloud conditions.

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Inter-comparison study of atmospheric <sup>222</sup>Rn and <sup>222</sup>Rn progeny monitors

Claudia Grossi Olivier Llido Felix Vogel Victor Kazan Alessandro Capuana

Abstract. The use of the noble gas radon (222Rn) as tracer for different research studies, for example observation-based estimation of greenhouse gas (GHG) fluxes, has led to the need of high-quality 222Rn activity concentration observations with high spatial and temporal resolution. So far a robust metrology chain for these measurements is not yet available. A 3-month inter-comparison campaign of atmospheric 222Rn and 222Rn progeny monitors based on different measurement techniques was realized during the fall and winter of 2016-2017 to evaluate: i) calibration and correction factors between monitors necessary to harmonize the atmospheric radon observations; and ii) the dependence of each monitor’s response in relation to the sampling height, meteorological and atmospheric aerosol conditions. Results of this study have shown that: i) all monitors were able to reproduce the atmospheric radon variability on daily basis; ii) linear regression fits between the monitors exhibited slopes between 0.62 and 1.17 and offsets ranging between −0.85 Bq m−3 and −0.23 Bq m−3 when sampling 2 m above ground level (a.g.l.). Corresponding results at 100 m a.g.l. exhibited slopes of 0.94 and 1.03 with offsets of −0.13 Bq m−3 and 0.01 Bq m−3, respectively; iii) no influence of atmospheric temperature and relative humidity on monitor responses was observed for unsaturated conditions; and iv) changes of the ratio between radon progeny and radon monitor responses were observed under very high atmospheric humidity and under very low atmospheric aerosol concentrations. However, a more statistically robust evaluation of these last influences based on a longer dataset should be conducted to improve the harmonization of the data.

TRACER

10.5194/amt-2019-378

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Atmospheric mercury in the southern hemisphere tropics: seasonal and diurnal variations and influence of inter-hemispheric transport

Dean Howard Peter F. Nelson Grant C. Edwards A. L. Morrison Jenny A. Fisher

Abstract. Mercury is a toxic element of serious concern for human and environmental health. Understanding its natural cycling in the environment is an important goal towards assessing its impacts and the effectiveness of mitigation strategies. Due to the unique chemical and physical properties of mercury, the atmosphere is the dominant transport pathway for this heavy metal, with the consequence that regions far removed from sources can be impacted. However, there exists a dearth of long-term monitoring of atmospheric mercury, particularly in the tropics and southern hemisphere. This paper presents the first two years of gaseous elemental mercury (GEM) measurements taken at the Australian Tropical Atmospheric Research Station (ATARS) in northern Australia, as part of the Global Mercury Observation System (GMOS). Annual mean GEM concentrations determined at ATARS (0.95 ± 0.12 ng m−3) are consistent with recent observations at other sites in the southern hemisphere. Comparison with GEM data from other Australian monitoring sites suggests a concentration gradient that decreases with increasing latitude. Seasonal analysis shows that GEM concentrations at ATARS are significantly lower in the distinct wet monsoon season than in the dry season. This result provides insight into alterations of natural mercury cycling processes as a result of changes in atmospheric humidity, oceanic/terrestrial fetch and convective mixing, and invites future investigation using wet mercury deposition measurements. Due to its location relative to the atmospheric equator, ATARS intermittently samples air originating from the northern hemisphere, allowing an opportunity to gain greater understanding of inter-hemispheric transport of mercury and other atmospheric species. Diurnal cycles of GEM at ATARS show distinct nocturnal depletion events that are attributed to dry deposition under stable boundary layer conditions. These cycles provide strong further evidence for the multi-hop model of global GEM cycling, whereby long-range transport is characterised by multiple surface depositions and re-emissions, rather than continuous transport over long distances.

Mercury

10.5194/acp-2017-307

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Citations (5)

Increasing the accuracy and temporal resolution of two-filter radon–222 measurements by correcting for the instrument response

Atmospheric measurement techniques (2016)

Alan D. Griffiths Scott Chambers Alastair G. Williams Sylvester Werczynski

Abstract. Dual-flow-loop two-filter radon detectors have a slow time response, which can affect the interpretation of their output when making continuous observations of near-surface atmospheric radon concentrations. While concentrations are routinely reported hourly, a calibrated model of detector performance shows that ∼ 40 % of the signal arrives more than an hour after a radon pulse is delivered. After investigating several possible ways to correct for the detector's slow time response, we show that a Bayesian approach using a Markov chain Monte Carlo sampler is an effective method. After deconvolution, the detector's output is redistributed into the appropriate counting interval and a 10 min temporal resolution can be achieved under test conditions when the radon concentration is controlled. In the case of existing archived observations, collected under less ideal conditions, the data can be retrospectively reprocessed at 30 min resolution. In one case study, we demonstrate that a deconvolved radon time series was consistent with the following: measurements from a fast-response carbon dioxide monitor; grab samples from an aircraft; and a simple mixing height model. In another case study, during a period of stable nights and days with well-developed convective boundary layers, a bias of 18 % in the mean daily minimum radon concentration was eliminated by correcting for the instrument response.

10.5194/amt-9-2689-2016

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Citations (35)

Radon-222 in boundary layer and free tropospheric continental outflow events at three ACE-Asia sites

Tellus B (2005)

W. Zahorowski Scott Chambers Tao Wang Chang‐Hee Kang Itsushi Uno

A 1-year record of hourly atmospheric radon-222 concentration observations at three ACE-Asia network sites—Hok Tsui (Hong Kong), Gosan (Jeju Island) and Mauna Loa Observatory (Hawaii)—is presented and discussed. The observations include the spring 2001 ACE-Asia intensive operation period. Site locations were chosen for the experimental characterization of both boundary layer (Hok Tsui, Gosan) and free tropospheric (Mauna Loa) continental outflow to the Pacific. A significant seasonal variability in background radon concentration is quantified at each site with the ratios of winter maximum to summer minimum background of 96, 15 and 3 for Hok Tsui, Gosan and Mauna Loa, respectively. Only during summer were background radon concentrations directly comparable with unperturbed marine values (~20 mBq m−3). The variability in radon signal was characterized at each site on diurnal to seasonal timescales. The seasonal variability in fetch regions for air masses experiencing the greatest and smallest terrestrial influence was characterized using 10-day back trajectories of air masses corresponding to radon concentrations higher (lower) than the 90th (10th) percentile value. The trajectory analyses for Hok Tsui and Gosan, as well as a direct analysis of the experimental results, further supports the previously postulated existence of a strong spatial heterogeneity in the radon source strength in East Asia. Back trajectories of free tropospheric air masses reaching Mauna Loa indicated source regions deep within the Asian continent primarily between 20 and 40°N. This fetch region is different from that influencing the Hok Tsui and Gosan sites. The radon concentration of air masses reaching Mauna Loa was shown to vary seasonally as well as with latitude of the predominant fetch region. Possible mechanisms of this phenomenon have been identified and include (a) seasonal variation in the radon source, (b) seasonal variation in the strength, frequency and/or efficiency of mechanisms that lift boundary layer air to the mid troposphere and (c) seasonal variation in the latitudinal axis of convection.

Fetch

Outflow

Annual cycle

Box model

10.3402/tellusb.v57i2.16776

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Citations (27)

Radon-222 in boundary layer and free tropospheric continental outflow events at three ACE-Asia sites

Tellus B (2005)

W. Zahorowski Scott Chambers Tao Wang Chang-Hee Kang Itsushi Uno

A 1-year record of hourly atmospheric radon-222 concentration observations at three ACE-Asia network sites—Hok Tsui (Hong Kong), Gosan (Jeju Island) and Mauna Loa Observatory (Hawaii)—is presented and discussed. The observations include the spring 2001 ACE-Asia intensive operation period. Site locations were chosen for the experimental characterization of both boundary layer (Hok Tsui, Gosan) and free tropospheric (Mauna Loa) continental outflow to the Pacific. A significant seasonal variability in background radon concentration is quantified at each site with the ratios of winter maximum to summer minimum background of 96, 15 and 3 for Hok Tsui, Gosan and Mauna Loa, respectively. Only during summer were background radon concentrations directly comparable with unperturbed marine values (∼20 mBq m −3 ). The variability in radon signal was characterized at each site on diurnal to seasonal timescales. The seasonal variability in fetch regions for air masses experiencing the greatest and smallest terrestrial influence was characterized using 10-day back trajectories of air masses corresponding to radon concentrations higher (lower) than the 90th (10th) percentile value. The trajectory analyses for Hok Tsui and Gosan, as well as a direct analysis of the experimental results, further supports the previously postulated existence of a strong spatial heterogeneity in the radon source strength in East Asia. Back trajectories of free tropospheric air masses reaching Mauna Loa indicated source regions deep within the Asian continent primarily between 20 and 40°N. This fetch region is different from that influencing the Hok Tsui and Gosan sites. The radon concentration of air masses reaching Mauna Loa was shown to vary seasonally as well as with latitude of the predominant fetch region. Possible mechanisms of this phenomenon have been identified and include (a) seasonal variation in the radon source, (b) seasonal variation in the strength, frequency and/or efficiency of mechanisms that lift boundary layer air to the mid troposphere and (c) seasonal variation in the latitudinal axis of convection. DOI: 10.1111/j.1600-0889.2005.00133.x

Outflow

10.1111/j.1600-0889.2005.00133.x

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Citations (61)

Biomass burning emissions in north Australia during the early dry season: an overview of the 2014 SAFIRED campaign

Marc Mallet Maximilien Desservettaz Branka Miljevic Anđelija Milić Zoran Ristovski

Abstract. The SAFIRED (Savannah Fires in the Early Dry Season) campaign took place from 29th of May, 2014 until the 30th June, 2014 at the Australian Tropical Atmospheric Research Station (ATARS) in the Northern Territory, Australia. The purpose of this campaign was to investigate emissions from fires in the early dry season in northern Australia. Measurements were made of biomass burning aerosols, volatile organic compounds, polycyclic aromatic carbons, greenhouse gases, radon, mercury cycle, and trace metals. Aspects of the biomass burning aerosol emissions investigated included; emission factors of various emitted species, physical and chemical aerosol properties, aerosol aging, micronutrient supply to the ocean, nucleation, and aerosol water uptake. Over the course of the month-long campaign, biomass burning signals were prevalent and emissions from several large single burning events were observed at ATARS. Biomass burning emissions dominated the gas and aerosol concentrations in this region. Nine major biomass burning events were identified and associated with intense or close individual smoke plumes. Dry season fires are extremely frequent and widespread across the northern region of Australia, which suggests that the measured aerosol and gaseous emissions at ATARS are likely representative of signals across the entire region of north Australia. Air mass forward trajectories show that these biomass burning emissions are carried north west over the Timor Sea and could influence the atmosphere over Indonesia and the tropical atmosphere over the Indian Ocean. The outcomes of this campaign will be numerous. This region is an environment with little human impact and provides a unique look into the characteristics of biomass burning aerosol without the influence of other significant emission sources. Relationships between the aerosol physical and chemical properties, gas concentrations and meteorological data for the entire month will provide fundamental knowledge required to understand the influence of early dry season burning in this tropical region on the atmosphere. In this paper we present characteristics of the biomass burning observed at the sampling site and provide an overview of the more specific outcomes of the SAFIRED campaign.

Trace gas

Dry season

10.5194/acp-2016-866

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Citations (5)