The distribution of sea-salt aerosol in the global troposphere

Murphy, D. M.; Froyd, K. D.; Bian, Huisheng; Brock, C. A.; Dibb, Jack E.; DiGangi, J. P.; Diskin, G. S.; Dollner, Maximilian; Kupc, Agnieszka; Scheuer, Eric; Schill, G. P.; Weinzierl, Bernadett; Williamson, Christina; Yu, Pengfei

doi:10.5194/acp-2018-1013

Cited by 21 publications

(26 citation statements)

References 36 publications

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“…The benchmark VSL halogen setup includes also the contribution of sea‐salt aerosol (SSA) recycling. Sea‐salt aerosols are generated by breaking waves on the ocean surface (Monahan et al, ; Smith et al, ) and can be transported well above the MBL where their washout efficiency decreases (Murphy et al, ). Heterogeneous halogen reactions taking place on the surface of SSA have previously been included in CAM‐Chem for HX, HOX, and XONO 2 species (Fernandez et al, ; Ordóñez et al, ), based on the assumption that the rate‐limiting step for the heterogeneous recycling reaction is the uptake of the inorganic halogen species on the aerosol surface (McFiggans et al, ).…”

Section: Methodsmentioning

confidence: 99%

Modeling the Sources and Chemistry of Polar Tropospheric Halogens (Cl, Br, and I) Using the CAM‐Chem Global Chemistry‐Climate Model

Fernández

Carmona-Balea

Cuevas

et al. 2019

J Adv Model Earth Syst

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Current chemistry climate models do not include polar emissions and chemistry of halogens.This work presents the first implementation of an interactive polar module into the very short-lived (VSL) halogen version of the Community Atmosphere Model with Chemistry (CAM-Chem) model. The polar module includes photochemical release of molecular bromine, chlorine, and interhalogens from the sea-ice surface, and brine diffusion of iodine biologically produced underneath and within porous sea-ice. It also includes heterogeneous recycling of inorganic halogen reservoirs deposited over fresh sea-ice surfaces and snow-covered regions. The polar emission of chlorine, bromine, and iodine reach approximately 32, 250, and 39 Gg/year for Antarctica and 33, 271, and 4 Gg/year for the Arctic, respectively, with a marked seasonal cycle mainly driven by sunlight and sea-ice coverage. Model results are validated against polar boundary layer measurements of ClO, BrO, and IO, and satellite BrO and IO columns. This validation includes satellite observations of IO over inner Antarctica for which an iodine "leapfrog" mechanism is proposed to transport active iodine from coastal source regions to the interior of the continent. The modeled chlorine and bromine polar sources represent up to 45% and 80% of the global biogenic VSL Cl and VSL Br emissions, respectively, while the Antarctic sea-ice iodine flux is~10 times larger than that from the Southern Ocean. We present the first estimate of the contribution of polar halogen emissions to the global tropospheric halogen budget. CAM-Chem includes now a complete representation of halogen sources and chemistry from pole-to-pole and from the Earth's surface up to the stratopause. Key Points:• The contribution of polar sea-ice sources to the global tropospheric halogen budget has been computed using the CAM-Chem model • The annual halogen flux from the sea-ice surface represents between 45% and 80% of the global chloro-and bromo-carbon oceanic VSL emissions • In Antarctica, the annual iodine sea-ice flux is~10 times larger than the oceanic inorganic iodine sourceSupporting Information:• Supporting Information S1

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Section: Methodsmentioning

confidence: 99%

Modeling the Sources and Chemistry of Polar Tropospheric Halogens (Cl, Br, and I) Using the CAM‐Chem Global Chemistry‐Climate Model

Fernández

Carmona-Balea

Cuevas

et al. 2019

J Adv Model Earth Syst

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“…Sa is the wet aerosol surface area on which IEPOX can be taken up (cm 2 cm -3 ), ra is the wet aerosol radius (cm), Dg is gas-phase diffusion coefficient of IEPOX (cm 2 s -1 ), and vmms is the mean molecular speed (cm s -1 ) of gas-phase IEPOX. 145 Second, we calculate the submicron aerosol pH without sea salt based on the results from previous studies (Noble and Prather, 1996;Middlebrook et al, 2003;Hatch et al, 2011;Allen et al, 2015;Guo et al, 2016;Bondy et al, 2018;Murphy et al, 2018), which showed that sea salt aerosols were dominantly externally mixed with sulfate-nitrate-ammonium rather than internally mixed. Therefore, sea salt is not expected to impact submicron aerosol pH significantly in the real atmosphere.…”

Section: Update To the Full Mechanism Of Iepox-soa Uptakementioning

confidence: 99%

A simplified parameterization of isoprene-epoxydiol-derived secondary organic aerosol (IEPOX-SOA) for global chemistry and climate models

Hodžić

Emmons

et al. 2019

Preprint

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Secondary organic aerosol derived from isoprene epoxydiols (IEPOX-SOA) is thought to contribute the dominant fraction of total isoprene SOA, but the current volatility-based lumped SOA parameterizations are not appropriate to represent the reactive uptake of IEPOX onto acidified aerosols. A full explicit modelling of this chemistry is however computationally expensive owing to the many species and reactions tracked, which makes it difficult to include it in chemistry climate models for long-15 term studies. Here we present three simplified parameterizations for IEPOX-SOA simulation, based on an approximate analytical / fitting solution of the IEPOX-SOA yield and formation timescale. The yield and timescale can then be directly calculated using the global model fields of oxidants, NO, aerosol pH and other key properties, and dry deposition rates. The advantage of the proposed parameterizations is that they do not require the simulation of the intermediates while retaining the key physico-chemical 20 dependencies. We have implemented the new parameterizations into the GEOS-Chem v11-02-rc chemical transport model, which has two empirical treatments for isoprene SOA (the volatility basis set (VBS) approach and a fixed 3% yield parameterization) and compared all of them to the case with detailed full chemistry. The best parameterization (PAR3) captures the global tropospheric burden of IEPOX-SOA and its spatio-temporal distribution (R 2 = 0.93) vs. those simulated by the full chemistry, while being 25 more computationally efficient (~5 times faster), and accurately captures the response to changes on NOx and SO2 emissions. On the other hand, the constant 3% yield that is now default in GEOS-Chem deviates strongly (R 2 = 0.65, 63% underestimation), as does the VBS (R 2 = 0.45, 78% underestimation), with neither parameterization capturing the response to emission changes. With the advent of new mass spectrometry instrumentation, many detailed SOA mechanisms are being developed, which will challenge 30 global and especially climate models with their computational cost. The methods developed in this study can be applied to other SOA pathways, which can allow including accurate SOA simulations in climate and global modeling studies in the future. Geosci. Model Dev. Discuss., https://doi.3 non-linear chemistry by various factors. The IEPOX-SOA yield from IEPOX are 17.3% (3.7/21.4) and 25.3% (1.9/7.5), respectively for (a) Amazon and (b) Beijing based on GEOS-Chem model calculations, which can be mainly explained by the higher available aerosol surface area in Beijing compared to Amazon. 65

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“…Our choice of 0.50 µm is based on the statistics of particle composition reported by the PALMS instrument. These measurements showed that non-volatile sea-salt and dust particles dominated the number and mass concentrations for particles with Dp ≥ 0.50 µm (Murphy et al, 2019;Froyd et al, manuscript in preparation, 2019). Defining 0.50 µm as the upper limit of the accumulation mode effectively separates particles that are mostly secondary in origin (the nucleation, Aitken, and accumulation modes) from the coarse mode that contains mostly primary particles in the ATom dataset.…”

Section: Integral Parametersmentioning

confidence: 99%

Aerosol size distributions during the Atmospheric Tomography (ATom) mission: methods, uncertainties, and data products

Brock¹,

Williamson²,

Kupc³

et al. 2019

Preprint

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Abstract. From 2016–2018 a DC-8 aircraft operated by the U.S. National Aeronautics and Space Administration (NASA) made four series of flights, profiling the atmosphere from 150 m to ~ 12 km above sea level from the Arctic to the Antarctic over both the Pacific and Atlantic Oceans. This program, the Atmospheric Tomography (ATom) mission, sought to sample the troposphere in a representative manner, making measurements of atmospheric composition in each season. This paper describes the aerosol microphysical measurements and derived quantities obtained during this mission. Dry size distributions from 2.7 nm to 4.8 µm in diameter were measured in-situ at 1 Hz using a battery of instruments: 10 condensation particle counters with different nucleation diameters, two ultra-high sensitivity aerosol size spectrometers (UHSAS), one of which measured particles surviving heating to 300 °C, and a laser aerosol spectrometer (LAS). The dry aerosol measurements were complemented by size distribution measurements from 0.5–930 µm diameter at near-ambient conditions using a cloud, aerosol, and precipitation spectrometer (CAPS) mounted under the wing of the DC-8. Dry aerosol number, surface area, and volume, and optical scattering and asymmetry parameter at several wavelengths from the near-UV to the near-IR were calculated from the measured dry size distributions (2.7 nm to 4.8 µm). Dry aerosol mass was estimated by combining the size distribution data with particle density estimated from independent measurements of aerosol composition with a high-resolution aerosol mass spectrometer and a single particle soot photometer. This paper briefly describes the instrumentation and fully documents the aircraft inlet and flow distribution system, the derivation of uncertainties, and the calculation of data products from combined size distributions. Comparisons between the instruments and direct measurements of some aerosol properties confirm that in-flight performance was consistent with calibrations and within stated uncertainties for the two deployments analyzed. The unique ATom dataset contains accurate, precise, high-resolution in-situ measurements of dry aerosol size distributions, and integral parameters, and estimates and measurements of optical properties, for particles

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The distribution of sea-salt aerosol in the global troposphere

Cited by 21 publications

References 36 publications

Modeling the Sources and Chemistry of Polar Tropospheric Halogens (Cl, Br, and I) Using the CAM‐Chem Global Chemistry‐Climate Model

Modeling the Sources and Chemistry of Polar Tropospheric Halogens (Cl, Br, and I) Using the CAM‐Chem Global Chemistry‐Climate Model

A simplified parameterization of isoprene-epoxydiol-derived secondary organic aerosol (IEPOX-SOA) for global chemistry and climate models

Aerosol size distributions during the Atmospheric Tomography (ATom) mission: methods, uncertainties, and data products

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