Key challenges for tropospheric chemistry in the Southern Hemisphere

Elementa Science of the Anthropocene, Journal Year: 2022, Volume and Issue: 10(1)

Published: Jan. 1, 2022

This commentary paper from the recently formed International Global Atmospheric Chemistry (IGAC) Southern Hemisphere Working Group outlines key issues in atmospheric composition research that particularly impact Hemisphere. In this article, we present a broad overview of many challenges for understanding chemistry Hemisphere, before focusing on most significant factors differentiate it Northern We sections importance biogenic emissions and fires showing these often dominate over anthropogenic regions. then describe how other influence air quality different parts Finally, role Ocean influencing conclude with description aims scope newly IGAC Group.

Language: Английский

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Multiple eco-regions contribute to the seasonal cycle of Antarctic aerosol size distributions

Atmospheric chemistry and physics, Journal Year: 2025, Volume and Issue: 25(2), P. 1145 - 1162

Published: Jan. 28, 2025

Abstract. In order to reduce the uncertainty of aerosol radiative forcing in global climate models, we need better understand natural sources which are important constrain current and pre-industrial climate. Here, analyse particle number size distributions (PNSDs) collected during a year (2015) across four coastal inland Antarctic research bases (Halley, Marambio, Dome C King Sejong). We utilise k-means cluster analysis separate PNSD data into six main categories. “Nucleation” “bursting” PNSDs occur 28 %–48 % time between sites, most commonly at sites Marambio Sejong where air masses mostly come from west travel over extensive regions sea ice, marginal ice open ocean likely arise new formation. “Aitken high”, low” “bimodal” 37 %–68 time, on Plateau, atmospheric transport ageing originating both boundary layer free troposphere. “Pristine” with low concentrations 12 %–45 Halley, located altitudes far melting influenced by west. Not only spray primary aerosols gas secondary sources, but also different impacting stations should be kept mind when deliberating upon precursor stations. infer that components pelagic sympagic strongly contribute annual seasonal cycle aerosols. Our simultaneous measurements stress importance variation biogeochemistry region.

Language: Английский

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Coalescence Scavenging Drives Droplet Number Concentration in Southern Ocean Low Clouds

Geophysical Research Letters, Journal Year: 2022, Volume and Issue: 49(7)

Published: March 27, 2022

Abstract Cloud droplet number concentration ( N d ) is a key microphysical property that largely controlled by the balance between sources and sinks of aerosols serve as cloud condensation nuclei (CCN). Despite being sink CCN, impact coalescence scavenging on Southern Ocean (SO) poorly known. We apply simple source‐and‐sink budget model based parameterizations to austral summer aircraft observations test behavior examine relative influence processes determine in SO stratocumulus clouds. The predicts with little bias correlation coefficient ∼0.7 compared observations. Coalescence found be an important CCN both liquid mixed‐phase precipitating reduces predicted much 90% depending precipitation rate. free tropospheric aerosol source controls more strongly than surface during summer.

Language: Английский

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Characterizing Ice Nucleating Particles Over the Southern Ocean Using Simultaneous Aircraft and Ship Observations

Journal of Geophysical Research Atmospheres, Journal Year: 2024, Volume and Issue: 129(2)

Published: Jan. 11, 2024

Abstract Supercooled liquid clouds are ubiquitous over the Southern Ocean (SO), even to temperatures below −20°C, and comprise a large fraction of marine boundary layer (MBL) clouds. Earth system models reanalysis products have struggled reproduce observed cloud phase distribution occurrence ice in region. Recent simulations found microphysical representation nucleation growth has impact on these properties, however, measurements SO nucleating particles (INPs) validate sparse. This study presents INPs from simultaneous aircraft ship campaigns conducted austral summer 2018, which include first situ observations above Our results confirm recent that INP concentrations uniformly lower than made late 1960s. While similar, higher efficiency supports model dominant composition varies with height. Model parameterizations based solely aerosol properties capture mean relationship between concentration temperature but not variability, is likely related only modest correlations environmental or metrics. Including wind speed addition activation parameterization reduces bias does explain range concentrations. Direct indirect inference size suggests MBL INPs, at least during Austral summer, dominated by diameters smaller 500 nm.

Language: Английский

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Circum-Antarctic abundance and properties of CCN and INPs

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(14), P. 9721 - 9745

Published: July 29, 2022

Abstract. Aerosol particles acting as cloud condensation nuclei (CCN) or ice-nucleating (INPs) play a major role in the formation and glaciation of clouds. Thereby they exert strong impact on radiation budget Earth. Data abundance properties both types are sparse, especially for remote areas world, such Southern Ocean (SO). In this work, we present unique results from ship-borne aerosol-particle-related situ measurements filter sampling SO region, carried out during Antarctic Circumnavigation Expedition (ACE) austral summer 2016–2017. An overview CCN INP concentrations over is provided and, using additional quantities, insights regarding possible sources origins presented. number spanned 2 orders magnitude, e.g. supersaturation 0.3 % values ranged roughly 3 to 590 cm−3. showed variable contributions organic inorganic material (inter-quartile range hygroscopicity parameter κ 0.2 0.9). No distinct size dependence was apparent, indicating homogeneous composition across sizes (critical dry diameter average between 30 110 nm). The contribution sea spray aerosol (SSA) concentration small. Ambient were measured temperature −5 −27 ∘C an immersion freezing method. Concentrations up at −16 100 m−3. Elevated (above 10 m−3 ∘C) when research vessel vicinity land (excluding Antarctica), with lower more constant sea. This, along backward-trajectory analyses, hints towards terrestrial and/or coastal being dominant close ice-free (non-Antarctic) land. pristine marine INPs may originate oceanic long-range transport. Sampled (PM10) analysed sodium methanesulfonic acid (MSA). Resulting mass used tracers primary secondary particles, respectively. Sodium, around 2.8 µg m−3, found dominate sampled, identified particle mass. MSA highly SO, 0.5 near ice edge. A correlation analysis yielded correlations coarse mode, unsurprisingly significant SSA that mode. correlated Aitken accumulation mode particles. together lack concentrations, underlines important non-SSA, probably secondarily formed population. did not significantly correlate any other physico-chemical parameter.

Language: Английский

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Ocean-atmosphere interactions: Different organic components across Pacific and Southern Oceans

The Science of The Total Environment, Journal Year: 2023, Volume and Issue: 878, P. 162969 - 162969

Published: March 22, 2023

Sea spray aerosol (SSA) particles strongly influence clouds and climate but the potential impact of ocean microbiota on SSA fluxes is still a matter active research. Here-by means in situ ship-borne measurements-we explore simultaneously molecular-level chemical properties organic (OM) oceans, sea ice, ambient PM2.5 aerosols along transect 15,000 km from western Pacific Ocean (36°13'N) to Southern (75°15'S). By orbitrap mass spectrometry optical characteristics, lignin-like material (24 ± 5 %) humic (57 8 were found dominate pelagic surface, while intermediate conditions observed Pacific-Southern waters. In marine atmosphere, we gradient features aerosol: (31 9 dominating coastal areas Ocean, whereas lipid-like (23 16 protein-like (11 10 OM controlled sympagic (sea ice-influence). The results this study showed that composition ocean, which changes with latitude, affects compositions atmosphere. This highlights importance global-scale monitoring close interaction between Sympagic primary polar regions must be treated differently other pelagic-type oceans.

Language: Английский

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Insight into global climatology of melting layer: latitudinal dependence and orographic relief

Theoretical and Applied Climatology, Journal Year: 2024, Volume and Issue: 155(6), P. 4863 - 4873

Published: March 13, 2024

Language: Английский

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Natural marine cloud brightening in the Southern Ocean

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(2), P. 1677 - 1685

Published: Feb. 1, 2023

Abstract. The number of cloud droplets per unit volume (Nd) is a fundamentally important property marine boundary layer (MBL) liquid clouds that, at constant water path, exerts considerable controls on albedo. Past work has shown that regional Nd direct correlation to primary productivity (PP) because the role seasonally varying, biogenically derived precursor gases in modulating secondary aerosol properties. These linkages are thought be observable over high-latitude oceans, where strong seasonal variability and meteorology covary mostly pristine environments. Here, we examine from 5 years MODIS Level 2-derived properties broad region summer eastern Southern Ocean adjacent marginal seas. We demonstrate latitudinal, longitudinal temporal gradients strongly correlated with passage air masses high-PP waters concentrated along Antarctic Shelf poleward 60∘ S. find albedo MBL latitudes south S significantly higher than similar path (LWP) north this latitude.

Language: Английский

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Measurement report: Understanding the seasonal cycle of Southern Ocean aerosols

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(6), P. 3749 - 3777

Published: March 29, 2023

Abstract. The remoteness and extreme conditions of the Southern Ocean Antarctic region have meant that observations in this are rare, typically restricted to summertime during research or resupply voyages. Observations aerosols outside summer season limited long-term stations, such as Kennaook / Cape Grim (KCG; 40.7∘ S, 144.7∘ E), which is situated northern latitudes Ocean, Japanese operated Syowa (SYO; 69.0∘ 39.6∘ E). Measurements midlatitudes important, particularly light recent highlighted latitudinal gradient exists across summertime. Here we present 2 years (March 2016–March 2018) from Macquarie Island (MQI; 54.5∘ 159.0∘ E) aerosol (condensation nuclei larger than 10 nm, CN10) cloud condensation (CCN at various supersaturations) concentrations. This important multi-year data set characterised, its features compared with sets KCG SYO together those recent, regionally relevant CN10 concentrations were highest by a factor ∼50 % all non-winter seasons other two similar (summer medians 530, 426 468 cm−3 KCG, MQI SYO, respectively). In wintertime, seasonal minima (142 152 cm−3, respectively), being distinctly lower (87 cm−3), likely result reduction sea spray generation due ice ocean cover around site. maxima observed stations different times year, exhibiting January having distinct February high. Comparison CCN0.5 between showed overall trends wintertime minima; however, exhibited slightly (∼10 %) higher (medians 158 145 whereas ∼40 winter 57 92 Spatial temporal analysed further contrasting coincident occurred aboard several voyages RSV Aurora Australis RV Investigator. Results study for validating improving our models highlight heterogeneity pristine need capture cycles.

Language: Английский

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Simulating Southern Ocean Aerosol and Ice Nucleating Particles in the Community Earth System Model Version 2

Journal of Geophysical Research Atmospheres, Journal Year: 2023, Volume and Issue: 128(8)

Published: March 21, 2023

Abstract Southern Ocean (SO) low‐level mixed phase clouds have been a long‐standing challenge for Earth system models to accurately represent. While improvements the Community System Model version 2 (CESM2) resulted in increased supercooled liquid SO and improved model radiative biases, simulated CESM2 now contain too little ice. Previous observational studies indicated that marine particles are major contributor cloud heterogeneous ice nucleation, process initiates number of processes govern properties. In this study, we utilize detailed aerosol nucleating particle (INP) measurements from two recent measurement campaigns assess abundance, size distributions, composition INP parameterizations use CESM2. Our results indicate has positive bias surface‐level total surface area at latitudes north 58°S. Measured populations were dominated by INPs present evidence refractory over assumed here be mineral dust INPs. Results highlight critical need distributions order adequately represent their response long‐term changes atmospheric transport patterns land change. We also discuss important cautions limitations applying commonly used parameterization remote regions like pristine SO.

Language: Английский

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