Browsing by Author "Werczynski, S"
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- ItemAerosol 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, AGPast 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.
- ItemCave radon exposure, dose, dynamics and mitigation(National Speleological Society, 2021-03) Waring, CL; Hankin, SI; Solomon, SB; Long, S; Yule, A; Blackley, R; Werczynski, S; Baker, ACMany caves around the world have very high concentrations of naturally occurring 222Rn that may vary dramatically with seasonal and diurnal patterns. For most caves with a variable seasonal or diurnal pattern, 222Rn concentration is driven by bi-directional convective ventilation, which responds to external temperature contrast with cave temperature. Cavers and cave workers exposed to high 222Rn have an increased risk of contracting lung cancer. The International Commission on Radiological Protection (ICRP) has re-evaluated its estimates of lung cancer risk from inhalation of radon progeny (ICRP 115) and for cave workers the risk may now (ICRP 137) be 4–6 times higher than previously recognized. Cave Guides working underground in caves with annual average 222Rn activity > 1,000 Bq m⁻3 and default ICRP assumptions (2,000 workplace hours per year, equilibrium factor F ₌ 0.4, dose conversion factor DCF ₌ 14 µSv (kBq h m⁻3)⁻1 could now receive a dose of > 20 mSv y₋1 . Using multiple gas tracers (δ13C-CO2, Rn and N2O), linked weather, source gas flux chambers, and convective air flow measurements a previous study unequivocally identified the external soil above Chifley Cave as the source of cave 222Rn. If the source of 222Rn is external to the cave, a strategy to lower cave 222Rn by passively decreasing summer pattern convective ventilation, which draws 222Rn into caves, is possible without harming the cave environment. A small net annual average temperature difference (warmer cave air) due to geothermal heat flux produces a large net annual volumetric air flow bias (2–5:1) favoring a winter ventilation pattern that flushes Rn from caves with ambient air. Rapid anthropogenic climate change over decades may heat the average annual external temperature relative to the cave temperature that is stabilized by the thermal inertia of the large rock mass. Relative external temperature increases due to climate change (Jenolan Caves, 2008–2018, 0.17°C) reduces the winter pattern air flow bias and increases Rn concentration in caves. © The Authors
- ItemConstraining 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, SRadon 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.
- ItemEstimating the near-surface daily fine aerosol load using hourly Radon-222 observations(Atmospheric Pollution Research (APR), 2013-01-01) Crawford, J; Zahorowski, W; Cohen, DD; Chambers, SD; Stelcer, E; Werczynski, SWe 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 needto be evaluated for each site. © 2013, Atomospheric Pollution Research (APR).
- ItemImproved estimation of total boundary layer radon for budget studies and regional integrations.(European Geosciences Union, 2010-05-02) Williams, AG; Zahorowski, W; Chambers, SD; Element, A; Werczynski, S; Griffiths, ADEstimation 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. On cloudless days, a large drop in radon concentrations across the inversion is evident from the vertical radon profiles. This is a result of radon depletion in the free atmosphere by radioactive decay (radon’s half-life is 3.8 days), and the “top-down” diffusion process associated with entrainment of this radon-depleted air into the ABL results in a range of radon gradients observed in the upper part of the mixed layer. When actively coupled boundary layer clouds are present, the profiles indicate strongly enhanced vertical mixing and venting of radon from the sub-cloud layer into the cloud layer. Under these conditions, the proportion of total-column radon remaining in the sub-cloud layer can sometimes be as low as 30%. Based on the enhanced understanding of vertical radon distributions in daytime terrestrial boundary layers gained from these airborne studies, refinements are suggested to the traditional estimation of total column radon from datasets where only surface-based radon measurements are available. These refinements are shown to result in improved estimates of total boundary layer radon in both clear and cloudy conditions. © Author(s) 2010
- ItemInfluence of turbulent mixing and air circulation in the lower atmosphere on fetch areas of selected WMO Global Atmosphere Watch baseline air pollution stations.(World Meteorological Organization, 2008-06-09) Zahorowski, W; Chambers, SD; Kang, CH; Crawford, J; Werczynski, S; Williams, AGThe World Meteorological Organisation (WMO) established the Global Atmosphere Watch (GAW) Programme in 1989. The scientific goals of GAW relate to investigating the role of atmospheric chemistry in global climate change, and include: understanding the complex mechanisms with respect to natural and anthropogenic atmospheric change; and improving the understanding of interactions between the atmosphere, ocean, and biosphere.
- ItemMap of radon flux at the Australian land surface.(European Geosciences Union, 2010-06-09) Griffiths, AD; Zahorowski, W; Element, A; Werczynski, SA 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, and maps of soil properties. The model was calibrated against a large 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. © Author(s) 2010
- ItemNIWA’s δ13C-CO2 measurement programme: twenty years of monitoring in New Zealand and Antarctica, including the performance assessment of an in-situ analyser at Baring Head(American Geophysical Union, 2018-12-13) Moss, RC; Brailsford, GW; Martin, R; Nankivell, C; Nicol, S; Trans, PP; Mikaloff-Fletcher, SE; Michel, S; Keeling, RF; Werczynski, S; Gorjan, P; Sperlich, PNIWA is monitoring atmospheric trace gas species at multiple locations in New Zealand and Antarctica. NIWA’s main monitoring sites include i) Baring Head (BHD), a coastal site at the Southern tip of New Zealand’s North Island, ii) Lauder (LAU), an inland site in the central South Island of New Zealand and iii) Arrival Heights (ARH), an observatory on Ross Island in McMurdo Sound in Antarctica. Stable carbon isotopes in atmospheric carbon dioxide (δ13C-CO2) are measured at all three sites and represent a tracer to constrain CO2 fluxes. NIWA’s δ13C-CO2 measurements started in 1997 at BHD and ARH, while it commenced in 2009 at LAU. At all three sites, air is sampled in flasks during specific meteorological conditions, i.e. during Southerly events at BHD to sample Southern Ocean background air, or during mid-afternoon at LAU when the atmospheric boundary layer is well mixed. All flasks are analysed for δ13C-CO2 at the main gaslab in Wellington, using the same Gas Chromatography coupled Isotope Ratio Mass Spectrometry (GC-IRMS) system, ensuring optimal internal data consistency. Our instrument comprises a purpose-built GC unit and a commercial IRMS (MAT 252, Thermo Fisher, Bremen, Germany). In the last 20 years, the δ13C-CO2 monitoring programme has generated 1,708 measurements, with about 1182 from BHD, 158 from ARH, 368 from LAU. BHD is also sampled for δ13C-CO2 analysis within the NOAA and the Scripps flask networks, providing continuous intercomparison time series. In collaboration with the Australian Nuclear Science and Technology Organisation (ANSTO), we monitor Radon at BHD since 2015. Radon indicates if the sampled air has been in contact with terrestrial air masses, highlighting the potential for contamination with CO2 from terrestrial sources, which would impact on δ13C-CO2 observations. We also collaborate with Thermo Fisher (Bremen, Germany) and deployed Delta Ray – an in-situ analyser for δ13C and δ18O in atmospheric CO2 – at BHD. We compare the Delta Ray time series of δ13C and δ18O to δ13C-CO2 measurements in co-located flask samples as well as to continuous CO2 mole fractions, Radon and meteorological data from BHD.
- ItemRadon tracer flux measurements of CO2, N2O and CH4 at Wagga Wagga: OASIS revisited?(Australian Government Bureau of Meteorology, 2017-11-12) Griffith, DWT; Wilson, SR; Griffiths, AD; Chambers, SD; Williams, AG; Werczynski, S; Sisoutham, O; Howitt, JA; Reardon, D; Leuning, RVertical profiles and suitably-conditioned surface time histories of the natural radioactive noble gas radon-222 (radon) have long been demonstrated to be useful as quantitative indicators of diurnal- to synoptic-scale mixing processes within the continental lower troposphere. Radon’s well-characterised and slowly-varying source function over (ice-free)terrestrial surfaces, together with its short half-life of 3.8 days, makes it a particularly suitable passive scalar for the evaluation of boundary layer and convective mixing parameterisation schemes in a range of regional and global climate and pollution transport models. We provide a brief overview of ANSTO measurement programs using radon to characterise vertical mixing in the lower atmosphere, together with examples of their applications in modelling and pollution studies. We then present preliminary results from recent field campaigns collecting high resolution vertical radon profiles in the terrestrial boundary layer over rural New South Wales, using a radon sampler mounted on an instrumented motor-glider. The flights were conducted in the lowest 1000m of the atmosphere and, together with simultaneous ground-based and tower measurements, document the dispersion of radon emissions accumulated below the nocturnal stable inversion into the developing daytime convective boundary layer during the important morning transition period.
- ItemVertical radon-222 profiles in the atmospheric boundary layer(CSIRO and the Bureau of Meteorology, 2011-11-15) Zahorowski, W; Williams, AG; Chambers, SD; Griffiths, AD; Crawford, J; Werczynski, S; Element, ARadon-222 (radon) is a naturally occurring radioactive tracer of air mass transport on different time and space scales. In particular, the vertical distribution of radon has been demonstrated to be useful for characterisation of exchange and mixing processes within the atmospheric boundary layer. In 2006 we started a program of research, using radon-222 to advance our understanding of these processes as part of a broader goal to improve parameterisation schemes for vertical mixing in the lower atmosphere. Two types of experiments have been conducted. The first is based on continuous hourly estimates of radon-222 concentration gradients at two meteorological towers, one focussing on near-surface gradients (2-50m) recorded on a 50m tower at Lucas Heights in New South Wales (34.05ºS, 150.98ºE), and the other on boundary layer gradients (20-200 m) measured on a 213m tower at the Cabauw Experimental Site for Atmospheric Research in the Netherlands (51.971ºN, 4.927ºE). The second experiment type relies on the collection of high resolution radon-222 vertical profiles up to 4,000 m above ground level using radon samplers mounted on an instrumented motorised research glider. In this presentation, we discuss selected results from a unique set of high resolution vertical radon profiles measured in 2007-2010 in clear and cloudy daytime terrestrial boundary layers over rural New South Wales. The profile examples reveal the characteristic structure and variability of three major types of daytime boundary layer: 1) dry convective boundary layers, 2) mixed layers topped with residual layers, and 3) convective boundary layers topped with coupled non-precipitating clouds. We demonstrate that important boundary layer processes are identifiable in the observed radon profiles, including ‘‘top down’’ mixing associated with entrainment in clear-sky cases and strongly enhanced venting and sub-cloud layer mixing when substantial active cumulus are present. A related presentation (Chambers et al. 2011) outlines some recent results based on our radon gradient measurements at the Lucas Heights tower. © 2011 CSIRO and the Bureau of Meteorology.