Observations of Clouds, Aerosols, Precipitation, and Surface Radiation over the Southern Ocean: An Overview of CAPRICORN, MARCUS, MICRE, and SOCRATES

Bulletin of the American Meteorological Society, Journal Year: 2020, Volume and Issue: 102(4), P. E894 - E928

Published: Nov. 30, 2020

Abstract Weather and climate models are challenged by uncertainties biases in simulating Southern Ocean (SO) radiative fluxes that trace to a poor understanding of cloud, aerosol, precipitation, processes, their interactions. Projects between 2016 2018 used situ probes, radar, lidar, other instruments make comprehensive measurements thermodynamics, surface radiation, cloud condensation nuclei (CCN), ice nucleating particles over the SO cold waters, ubiquitous liquid mixed-phase clouds common this pristine environment. Data including soundings were collected from NSF–NCAR G-V aircraft flying north–south gradients south Tasmania, at Macquarie Island, on R/V Investigator RSV Aurora Australis . Synergistically these data characterize boundary layer free troposphere environmental properties, represent most type available oceanic polar front, sector cyclones, across seasons. Results show largely environments with numerous small few large aerosols above suggesting new particle formation limited long-range transport continents, high variability CCN droplet concentrations, supercooled water thin, multilayered clouds, often small-scale generating cells near top. These observations demonstrate how properties depend while highlighting importance dynamics turbulence likely drive heterogeneity phase. Satellite retrievals confirmed low responsible for radiation biases. The combination is examining meteorology couple control energy budgets.

Language: Английский

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Ice‐Nucleating Particles That Impact Clouds and Climate: Observational and Modeling Research Needs

Reviews of Geophysics, Journal Year: 2022, Volume and Issue: 60(2)

Published: April 21, 2022

Abstract Atmospheric ice‐nucleating particles (INPs) play a critical role in cloud freezing processes, with important implications for precipitation formation and radiative properties, thus weather climate. Additionally, INP emissions respond to changes the Earth System climate, example, desertification, agricultural practices, fires, therefore may introduce climate feedbacks that are still poorly understood. As knowledge of nature origins INPs has advanced, regional global weather, system models have increasingly begun link ice processes model‐simulated aerosol abundance types. While these recent advances exciting, coupling simulated also makes physics simulations susceptible uncertainties simulation INPs, which constrained by observations. Advancing predictability reasonable spatiotemporal resolution will require an increased focus on research bridges measurement modeling communities. This review summarizes current state identifies gaps from both observational perspectives. In particular, we emphasize needs two key areas: (a) closure between quantities (b) skillful within existing models. We discuss various particle types briefly challenges faced understanding impacts present‐day Finally, identify priority directions observations improve their interactions System.

Language: Английский

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Influences of Recent Particle Formation on Southern Ocean Aerosol Variability and Low Cloud Properties

Journal of Geophysical Research Atmospheres, Journal Year: 2021, Volume and Issue: 126(8)

Published: March 26, 2021

Abstract Controls on pristine aerosol over the Southern Ocean (SO) are critical for constraining strength of global indirect forcing. Observations summertime SO clouds and aerosols in synoptically varied conditions during 2018 SOCRATES aircraft campaign reveal novel mechanisms influencing aerosol‐cloud interactions. The free troposphere (3–6 km) is characterized by widespread, frequent new particle formation events contributing to much larger concentrations (≥1,000 mg −1 ) condensation nuclei (diameters > 0.01 μm) than typical sub‐tropical regions. Synoptic‐scale uplift warm conveyor belts sub‐polar vortices lifts marine biogenic sulfur‐containing gases free‐tropospheric environments favorable generating Aitken‐mode particles (0.01–0.1 μm). Free‐tropospheric Aitken subside into boundary layer, where they grow size dominate sulfur‐based cloud (CCN) driving droplet number ( N d ∼ 60–100 cm −3 ). Evidence presented a hypothesized ‐ buffering mechanism which maintains persistently high against precipitation removal through CCN replenishment from activation growth layer particles. Nudged hindcasts Community Atmosphere Model (CAM6) found underpredict accumulation mode , impacting brightness interactions indicating incomplete representations associated with ocean biology.

Language: Английский

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Measurement report: Cloud processes and the transport of biological emissions affect southern ocean particle and cloud condensation nuclei concentrations

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(5), P. 3427 - 3446

Published: March 5, 2021

Abstract. Long-range transport of biogenic emissions from the coast Antarctica, precipitation scavenging, and cloud processing are main processes that influence observed variability in Southern Ocean (SO) marine boundary layer (MBL) condensation nuclei (CN) (CCN) concentrations during austral summer. Airborne particle measurements on HIAPER GV north–south transects between Hobart, Tasmania, 62∘ S Clouds, Radiation Aerosol Transport Experimental Study (SOCRATES) were separated into four regimes comprising combinations high low CCN CN. In 5 d HYSPLIT back trajectories, air parcels with elevated almost always shown to have crossed Antarctic coast, a location phytoplankton relative rest SO region south Australia. The presence was also consistent fractions over their trajectory, suggesting there substantial growth biogenically formed particles through processing. Cases fraction, due cumulus clouds, had CN concentrations, previously reported new formation outflow regions. Measurements associated previous 1.5 trajectory indicating effectively scavenged by precipitation. A coarse-mode fitting algorithm used determine primary aerosol (PMA) contribution, which accounted for <20 % (at 0.3 supersaturation) droplet number concentrations. Vertical profiles large (Dp>0.07 µm) indicated occurs more frequently above MBL; however, recently typically MBL, volatile compound oxidation products. R/V Investigator as part second Aerosols, Precipitation, atmospheric Composition Over southeRn (CAPRICORN-2) campaign conducted same period SOCRATES study. near Australia, likely continental coastal emissions. source south, sources midlatitudes, enhanced sink cyclonic circulation Ferrel polar cells (around 60∘ S) create opposing latitudinal gradients concentration an minimum 55 S. airborne not influenced Australian but still show evidence S, addition, gradient composition, Tasmanian coasts, is apparent hygroscopicity derived spectra size distribution. hygroscopic north, greater fraction sea salt PMA, less sulfate organic originating Antarctica.

Language: Английский

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Physical and Chemical Properties of Cloud Droplet Residuals and Aerosol Particles During the Arctic Ocean 2018 Expedition

Journal of Geophysical Research Atmospheres, Journal Year: 2022, Volume and Issue: 127(11)

Published: May 25, 2022

Detailed knowledge of the physical and chemical properties sources particles that form clouds is especially important in pristine areas like Arctic, where particle concentrations are often low observations sparse. Here, we present situ cloud aerosol measurements from central Arctic Ocean August-September 2018 combined with air parcel source analysis. We provide direct experimental evidence Aitken mode (particles diameters ≲70 nm) significantly contribute to condensation nuclei (CCN) or droplet residuals, after freeze-up sea ice transition toward fall. These were associated spent more time over pack ice, while size distributions dominated by accumulation ≳70 showed a stronger contribution oceanic slightly different regions. This was accompanied changes average composition an increased relative organic material Addition mass due aqueous-phase chemistry during in-cloud processing probably small given fact observed very similar both whole-air residual data. aerosol-cloud interaction valuable insight into origin CCN Ocean.

Language: Английский

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The biogeochemistry of marine dimethylsulfide

Nature Reviews Earth & Environment, Journal Year: 2023, Volume and Issue: 4(6), P. 361 - 376

Published: June 7, 2023

Language: Английский

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The Puy de Dôme ICe Nucleation Intercomparison Campaign (PICNIC): comparison between online and offline methods in ambient air

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(4), P. 2651 - 2678

Published: Feb. 29, 2024

Abstract. Ice crystal formation in mixed-phase clouds is initiated by specific aerosol particles, termed ice-nucleating particles (INPs). Only a tiny fraction of all are INPs, providing challenge for contemporary INP measurement techniques. Models have shown that the presence INPs can impact their radiative properties and induce precipitation formation. However, qualified implementation models, techniques able to accurately detect temperature-dependent concentration needed. Here we present measurements concentrations ambient air under conditions relevant from total 10 methods over 2 weeks October 2018 at Puy de Dôme observatory central France. A special focus this intercomparison campaign was placed on having overlapping sampling periods. Although variety different principles were used, majority data show within factor 5 one another, demonstrating suitability instruments derive model-relevant data. Lower values comparability likely due instrument-specific features such as lamina spreading continuous-flow diffusion chambers, need account phenomena when interpreting online instruments. Moreover, consistently higher observed filters collected rooftop station without use an inlet.

Language: Английский

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Southern Ocean latitudinal gradients of cloud condensation nuclei

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(16), P. 12757 - 12782

Published: Aug. 30, 2021

Abstract. The Southern Ocean region is one of the most pristine in world and serves as an important proxy for pre-industrial atmosphere. Improving our understanding natural processes this likely to result largest reductions uncertainty climate earth system models. While remoteness from anthropogenic continental sources responsible its clean atmosphere, also results dearth atmospheric observations region. Here we present a statistical summary latitudinal gradient aerosol (condensation nuclei larger than 10 nm, CN10) cloud condensation (CCN at various supersaturations) concentrations obtained five voyages spanning between Australia Antarctica late spring early autumn (October March) 2017/18 austral seasons. Three main regions influence were identified: northern sector (40–45∘ S), where coexisted with background marine populations; mid-latitude (45–65∘ populations reflected mixture biogenic sea-salt aerosol; southern (65–70∘ south polar front, greatly reduced primarily biologically derived sulfur species significant history Antarctic free troposphere. showed highest number median (25th 75th percentiles) CN10 CCN0.5 681 (388–839) cm−3 322 (105–443) cm−3, respectively. Concentrations mid-latitudes typically around 350 160 CCN0.5, In sector, rose markedly, reaching 447 (298–446) 232 (186–271) composition was marked by distinct drop sea salt increase both sulfate fraction absolute concentrations, resulting substantially higher CCN0.5/CN10 activation ratio 0.8 compared 0.4 mid-latitudes. Long-term measurements land-based research stations surrounding found be good representations their respective latitudes; however study highlighted need more long-term CCN Cape Grim (40∘39′ S) corresponded sectors, while only sector. Measurements simultaneous 2-year campaign Macquarie Island (54∘30′ represent all well. southernmost latitudes differed significantly these stations, previous work suggests that on East coastline do not sea-ice Further are needed capture long-term, seasonal longitudinal variability across Ocean.

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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Ocean flux of salt, sulfate, and organic components to atmospheric aerosol

Earth-Science Reviews, Journal Year: 2023, Volume and Issue: 239, P. 104364 - 104364

Published: March 10, 2023

Language: Английский

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