Conference Agenda

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Session Overview
AAS P5: Optical properties, remote sensing, black and brown carbon (Poster Session)
Tuesday, 31/Aug/2021:
2:10pm - 3:10pm


An overview of the modelling methods for the optical properties of internally mixed black carbon

Baseerat Romshoo, Thomas Müller, Alfred Wiedensohler

Leibniz Institute for Tropospheric Studies(TROPOS), Germany

Black carbon (BC) optical properties are required in global climate models in order to estimate the BC radiative forcing. The assumption of BC particles as spheres is widely used in global models, which has found to cause discrepancies in the optical results. Therefore, there has been an increase in the model-based studies that provide databases and parametrisation schemes for the optical properties of BC as more realistic fractal morphology. In this overview study, an up-to-date description of our knowledge on modeling the optical properties of internally mixed BC using fractal morphology is provided.

EAC2021_AAS P5-1_471_Romshoo_a.pdf

Brown carbon aerosol in an urban atmosphere in Karlsruhe, Germany: light absorption, chromophores, and chemical characteristics

Feng Jiang1,2, Harald Saathoff1, Junwei Song1,2, Linyu Gao1,2, Magdalena Vallon1, Thomas Leisner1,3, Stefan Norra2

1Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, 76344 Eggenstein–Leopoldshafen, Germany; 2Institute of Geography and Geoecology, Working Group for Environmental Mineralogy and Environmental System Analysis, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany; 3Institute of Environmental Physics, Heidelberg University, 69120 Heidelberg, Germany

A field campaign about brown carbon was conducted in downtown Karlsruhe, a city of 300000 inhabitants in southwest Germany. In this study, optical properties were measured by Aqualog and chemical characteristics were detected by the mass spectrometer. Parallel factor (PARAFAC) analysis allowed for the identification of four optically different types of methanol-soluble compounds. Humic-like substances and oxygenated organic species dominated in summer and biomass burning components dominated in winter. Furthermore, five nitroaromatic compounds contributed 0.2%-0.9% to total organic mass, but can explain 3%-6% of the absorption at 365nmn in winter.

EAC2021_AAS P5-2_426_Jiang_a.pdf
EAC2021_AAS P5-2_426_Jiang_b.pptx

The spatio-temporal evolution of black carbon in the North-West European ‘air pollution hotspot’: initial findings from a new long-term network

Kevin P. Wyche1, Rebecca L. Cordell2, Megan L. Smith1, Kirsty L. Smallbone1, Peter Lyons1, Sarkawt M. L. Hama2,3, Paul S. Monks2, Jeroen Staelens4, Jelle Hofman4,5, Chrisophe Stroobants4, Edward Roekens4, Gerard P. A. Kos6, Ernie P. Weijers7, Pavlos Panteliadis8, Marieke B. A. Dijkema8,9

1University of Brighton, United Kingdom; 2University of Leicester, United Kingdom; 3University of Surrey, United Kingdom; 4Flanders Environment Agency, Belgium; 5Holst Centre, the Netherlands; 6Netherlands Organisation for Applied Scientific Research, the Netherlands; 7National Institute for Public Health and the Environment, the Netherlands; 8Public Health Service of Amsterdam, the Netherlands; 9Institute for Risk Assessment Science, the Netherlands

Particulate black carbon has a range of negative impacts on health, environment and climate, however despite this there are relatively few long-term studies on its ambient distribution as an air pollutant. To address this lack of data, and to provide greater insight into the spatio-temporal distribution of black carbon and to assess potential influencing factors, a new, permanent monitoring network was established with sites in four northwest European cities: London, Leicester, Amsterdam, Antwerp. We report here an analysis of first measurements made by the network over a twenty-seven-month period, alongside data from pre-existing comparator urban roadside and rural background sites.

EAC2021_AAS P5-3_126_Wyche.pdf

Aerosol measurements during EUREC4A campaign

Niccolò Losi1, Luca Ferrero1, Claudia Pasquero1,2, Alessandra Bigogno1, Amedeo Manuel Cefalì1, Lorenzo Scibetta1, Ezio Bolzacchini1

1Department of Environmental Sciences, University of Milano Bicocca, Milano, 20126, Italy; 2Institute of Atmospheric and Climate Sciences, CNR, Bologna, Italy

EUREC4A campaign (20 January - 23 February 2020) took place in the downstream winter trades of the North Atlantic, eastward and south-eastward of Barbados. The main purpose of EUREC4A is to improve our understanding of the factors that influence clouds in the trades at different scales. On the particle scale, aerosol properties imprint themselves on the cloud microstructure and atmospheric heating rate of light-absorbing aerosol species acts on the available energy for cloud formation and dynamics. Therefore measurements were performed to characterize aerosols and a new methodology was applied to experimentally determine the HR induced by LAA during EUREC4A campaign.

EAC2021_AAS P5-4_513_Losi.pdf

The Red Sky: investigating the hurricane Ophelia Saharan dust and biomass burning aerosol event

Kevin P. Wyche1, Hugo Ricketts2,3, Matthew Brolly1, Kirsty L. Smallbone1

1University of Brighton, United Kingdom; 2University of Manchester, United Kingdom; 33National Centre for Atmospheric Science, United Kingdom

On 16th October 2017 ex-hurricane Ophelia passed over the UK, bringing with it a unique aerosol loading which caused the Sun and sky to turn dramatically red. Here we use an ensemble of modelling and remote sensing techniques in a ‘top-down, bottom-up’ approach comprising instruments onboard orbital platforms and a ground-based lidar, to interrogate Opelia's aerosol-cloud matrix to determine its composition and origins. Satellite observations were employed to provide a detailed, holistic ‘snapshot’ with high spatial coverage but low temporal resolution and a ground-based lidar was used to provide complementary, near real-time information on the types of entrained particles.

EAC2021_AAS P5-5_127_Wyche.pdf

Modelling depolarisation and lidar ratios of dried sea salt aerosol particles

Franz Kanngießer1, Michael Kahnert1,2

1Chalmers University of Technology, Sweden; 2Swedish Meteorological and Hydrological Institute

Linear backscattering depolarisation ratio and lidar ratio of dried sea salt aerosol were modelled simultaneously with cube-like superellipsoids. The impact of non-ideal shape deviations and changes in refractive index on the optical properties were studied. To investigate random shape deviations two types of random geometries, convex polyhedra and Gaussian random cubes were employed. The former resulted in depolarisation ratio scattered around values for cubical reference shapes. The latter type introduced a bias. Changes in refractive index impact both depolarisation ratios and lidar ratios. The convex polyhedra are currently used as a basis to study moistened sea salt aerosol.

EAC2021_AAS P5-6_388_Kanngießer.pdf

Global spatial distribution of the combined effect of aerosols and water vapour on solar radiation

Mª Ángeles Obregón1,2, Antonio Serrano1, Maria João Costa2,3,4, Ana Maria Silva2

1Department of Physics, University of Extremadura, Badajoz, 06006, Spain; 2Institute of Earth Sciences, Institute for Advanced Studies and Research, University of Évora, Évora, 7000-671, Portugal; 3Department of Physics, School of Sciences and Technology, University of Évora, Évora, 7000-671, Portugal; 4EaRSLab – Earth Remote Sensing Laboratory, University of Évora, Évora, 7000-671, Portugal

This study aims to calculate combined and individual effects of the aerosol optical thickness (AOT) and precipitable water vapour (PWV) on the solar radiation reaching the Earth's surface, and to analyse their global spatial variation. For that purpose, a novel and validated methodology is applied to CERES-SYN1deg products for the period 2000-2019. Spatial distributions of AOT and PWV effects, both individually and combined, show a close link with the spatial distributions of AOT and PWV. The global average AOT-PWV effect is more negative (-13.9%), while the average AOT effect is -2.3% and the average PWV effect is -12.1%.

EAC2021_AAS P5-7_480_Obregón.pdf