Urban air quality in a coastal city: Wollongong during the MUMBA campaign

We present findings from the Measurements of Urban, Marine and Biogenic Air (MUMBA) campaign, which took place in the coastal city of Wollongong in New SouthWales, Australia. We focus on a few key air quality indicators, along with a comparison to regional scale chemical transport model predictions at a spatial resolution of 1 km by 1 km. We find that the CSIRO chemical transport model provides accurate simulations of ozone concentrations at most times, but underestimates the ozone enhancements that occur during extreme temperature events. Themodel alsomeets previously published performance standards for fine particulate matter less than 2.5 microns in diameter (PM2.5), and the larger aerosol fraction (PM10). We explore the observed composition of the atmosphere within this urban air-shed during the MUMBA campaign and discuss the different influences on air quality in the city. Our findings suggest that further improvements to our ability to simulate air quality in this coastal city can be made through more accurate anthropogenic and biogenic emissions inventories and better understanding of the impact of extreme temperatures on air quality. The challenges in modelling air quality within the urban air-shed ofWollongong, including difficulties in accurate simulation of the local meteorology, are likely to be replicated in many other coastal cities in the Southern Hemisphere

Oceanic phytoplankton are a potentially important source of benzenoids to the remote marine atmosphere

International audienceAbstract Benzene, toluene, ethylbenzene and xylenes can contribute to hydroxyl reactivity and secondary aerosol formation in the atmosphere. These aromatic hydrocarbons are typically classified as anthropogenic air pollutants, but there is growing evidence of biogenic sources, such as emissions from plants and phytoplankton. Here we use a series of shipborne measurements of the remote marine atmosphere, seawater mesocosm incubation experiments and phytoplankton laboratory cultures to investigate potential marine biogenic sources of these compounds in the oceanic atmosphere. Laboratory culture experiments confirmed marine phytoplankton are a source of benzene, toluene, ethylbenzene, xylenes and in mesocosm experiments their sea-air fluxes varied between seawater samples containing differing phytoplankton communities. These fluxes were of a similar magnitude or greater than the fluxes of dimethyl sulfide, which is considered to be the key reactive organic species in the marine atmosphere. Benzene, toluene, ethylbenzene, xylenes fluxes were observed to increase under elevated headspace ozone concentration in the mesocosm incubation experiments, indicating that phytoplankton produce these compounds in response to oxidative stress. Our findings suggest that biogenic sources of these gases may be sufficiently strong to influence atmospheric chemistry in some remote ocean regions

Comprehensive aerosol and gas data set from the Sydney Particle Study

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, line https://doi.org/10.4225/08/57903B83D6A5D \u3ehttps://doi.org/10.4225/08/57903B83D6A5D) and Keywood et al. (2016b, line https://doi.org/10.4225/08/5791B5528BD63 \u3ehttps://doi.org/10.4225/08/5791B5528BD63)

Urban Air Quality in a Coastal City: Wollongong during the MUMBA Campaign

We present findings from the Measurements of Urban, Marine and Biogenic Air (MUMBA) campaign, which took place in the coastal city of Wollongong in New South Wales, Australia. We focus on a few key air quality indicators, along with a comparison to regional scale chemical transport model predictions at a spatial resolution of 1 km by 1 km. We find that the CSIRO chemical transport model provides accurate simulations of ozone concentrations at most times, but underestimates the ozone enhancements that occur during extreme temperature events. The model also meets previously published performance standards for fine particulate matter less than 2.5 microns in diameter (PM2.5), and the larger aerosol fraction (PM10). We explore the observed composition of the atmosphere within this urban air-shed during the MUMBA campaign and discuss the different influences on air quality in the city. Our findings suggest that further improvements to our ability to simulate air quality in this coastal city can be made through more accurate anthropogenic and biogenic emissions inventories and better understanding of the impact of extreme temperatures on air quality. The challenges in modelling air quality within the urban air-shed of Wollongong, including difficulties in accurate simulation of the local meteorology, are likely to be replicated in many other coastal cities in the Southern Hemisphere

Sea2Cloud: from biogenic emission fluxes to cloud properties in the South West Pacific

International audienceThe goal of the Sea2Cloud project is to study the interplay between surface oceanbiogeochemical and physical properties, fluxes to the atmosphere and ultimately their impacton cloud formation under minimal direct anthropogenic influence. Here we present aninterdisciplinary approach, combining atmospheric physics and chemistry with marinebiogeochemistry, during a voyage between 41 and 47°S in March 2020. In parallel to ambientmeasurements of atmospheric composition and seawater biogeochemical properties, wedescribe semi-controlled experiments to characterize nascent sea spray properties andnucleation from gas-phase biogenic emissions. The experimental framework for studying theimpact of the predicted evolution of ozone concentration in the Southern Hemisphere is alsodetailed. After describing the experimental strategy, we present the oceanic and meteorologicalcontext including provisional results on atmospheric thermodynamics, composition, and fluxmeasurements. In situ measurements and flux studies were carried out on different biologicalcommunities by sampling surface seawater from subantarctic, subtropical and frontal watermasses. Air-Sea-Tanks (ASIT) were used to quantify biogenic emissions of trace gases underrealistic environmental conditions, with nucleation observed in association with biogenicseawater emissions. Sea spray continuously generated produced sea spray fluxes of 34% oforganic matter by mass, of which 4% particles had fluorescent properties, and which sizedistribution ressembled the one found in clean sectors of the Southern Ocean. The goal ofSea2Cloud is to generate realistic parameterizations of emission flux dependences of tracegases and nucleation precursors, sea spray, cloud condensation nuclei and ice nuclei usingseawater biogeochemistry, for implementation in regional atmospheric model