Ship-borne observations of sea fog and rain chemistry over the North and South Pacific Ocean

Kim, Hyun Jae; Lee, Taehyoung; Park, Taehyun; Park, Gyutae; Collett, Jeffrey L.; Park, Keyhong; Ahn, JaeKyoung; Ban, Jihee; Kang, Seok‐Won; Kim, Kyunghoon; Park, Seung-Myung; Jho, Eun Hea; Choi, Yongjoo

doi:10.1007/s10874-020-09403-8

Cited by 7 publications

(3 citation statements)

References 55 publications

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“…The model is driven by assimilated meteorological fields from the NASA Global Modeling and Assimilation Office's Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) system (Gelaro et al, 2017). These fields include in particular cloud water liquid and ice content, cloud volume fraction, and 3-D liquid and ice precipitation fluxes, updated every 3 h. GEOS-Chem includes detailed NO x -hydrocarbon-aerosol-halogen chemistry (Mao et al, 2013;Kim et al, 2015;Travis et al, 2016;Sherwen et al, 2016), and here we have added recent halogen updates (X. . The model distinguishes between fine and coarse aerosol but does not otherwise include aerosol microphysics.…”

Section: Model Descriptionmentioning

confidence: 99%

Global modeling of cloud water acidity, precipitation acidity, and acid inputs to ecosystems

et al. 2020

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Abstract. Cloud water acidity affects the atmospheric chemistry of sulfate and organic aerosol formation, halogen radical cycling, and trace metal speciation. Precipitation acidity including post-depositional inputs adversely affects soil and freshwater ecosystems. Here, we use the GEOS-Chem model of atmospheric chemistry to simulate the global distributions of cloud water and precipitation acidity as well as the total acid inputs to ecosystems from wet deposition. The model accounts for strong acids (H2SO4, HNO3, and HCl), weak acids (HCOOH, CH3COOH, CO2, and SO2), and weak bases (NH3 as well as dust and sea salt aerosol alkalinity). We compile a global data set of cloud water pH measurements for comparison with the model. The global mean observed cloud water pH is 5.2±0.9, compared to 5.0±0.8 in the model, with a range from 3 to 8 depending on the region. The lowest values are over East Asia, and the highest values are over deserts. Cloud water pH over East Asia is low because of large acid inputs (H2SO4 and HNO3), despite NH3 and dust neutralizing 70 % of these inputs. Cloud water pH is typically 4–5 over the US and Europe. Carboxylic acids account for less than 25 % of cloud water H+ in the Northern Hemisphere on an annual basis but 25 %–50 % in the Southern Hemisphere and over 50 % in the southern tropical continents, where they push the cloud water pH below 4.5. Anthropogenic emissions of SO2 and NOx (precursors of H2SO4 and HNO3) are decreasing at northern midlatitudes, but the effect on cloud water pH is strongly buffered by NH4+ and carboxylic acids. The global mean precipitation pH is 5.5 in GEOS-Chem, which is higher than the cloud water pH because of dilution and below-cloud scavenging of NH3 and dust. GEOS-Chem successfully reproduces the annual mean precipitation pH observations in North America, Europe, and eastern Asia. Carboxylic acids, which are undetected in routine observations due to biodegradation, lower the annual mean precipitation pH in these areas by 0.2 units. The acid wet deposition flux to terrestrial ecosystems taking into account the acidifying potential of NO3- and NH4+ in N-saturated ecosystems exceeds 50 meqm-2a-1 in East Asia and the Americas, which would affect sensitive ecosystems. NH4+ is the dominant acidifying species in wet deposition, contributing 41 % of the global acid flux to continents under N-saturated conditions.

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Section: Model Descriptionmentioning

confidence: 99%

Global modeling of cloud water acidity, precipitation acidity, and acid inputs to ecosystems

et al. 2020

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“…Marine cloud water can also form Na and OC coatings on phyllosilicate particles because Na and OCs are dominant components in marine cloud water (Straub et al, 2007). Given that 500 nm of phyllosilicate particles with a 100 nm-thick water layer at pH 1.0 was incorporated into typical marine cloud water (diameter 10 µm, pH 4.0, Boris et al, 2016;Kim et al, 2019;Shah et al, 2020), the pH of aerosol particles was 3.97. The increase in aerosol pH by cloud processes decreases Fe sol % because of the precipitation of nano-ferrihydrite, with the sole consideration of inorganic Fe chemistry (Spokes et al, 1994;Shi et al, 2015;Maters et al, 2016).…”

Section: Reconstruction Alteration Processes Of Fe Based On Ph Ppd An...mentioning

confidence: 99%

Iron (Fe) speciation in size-fractionated aerosol particles in the Pacific Ocean: The role of organic complexation of Fe with humic-like substances in controlling Fe solubility

et al. 2022

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Abstract. Atmospheric deposition is one of the main sources of dissolved iron (Fe) in the ocean surfaces. Atmospheric processes are recognized as controlling fractional Fe solubility (Fesol%) in marine aerosol particles. However, the impact of these processes on Fesol% remains unclear. One of the reasons for this is the lack of field observations focusing on the relationship between Fesol% and Fe species in marine aerosol particles. In particular, the effects of organic ligands on Fesol% have not been thoroughly investigated in observational studies. In this study, Fe species in size-fractionated aerosol particles in the Pacific Ocean were determined using X-ray absorption fine structure (XAFS) spectroscopy. The internal mixing states of Fe and organic carbon were investigated using scanning transmission X-ray microscopy (STXM). The effects of atmospheric processes on Fesol% in marine aerosol particles were investigated based on the speciation results. Iron in size-fractionated aerosol particles was mainly derived from mineral dust, regardless of aerosol diameter, because the enrichment factor of Fe was almost 1 in both coarse (PM>1.3) and fine aerosol particles (PM1.3). Approximately 80 % of the total Fe (insoluble + labile Fe) was present in PM>1.3, whereas labile Fe was mainly present in PM1.3. The Fesol% in PM>1.3 was not significantly increased (2.56±2.53 %, 0.00 %–8.50 %, n=20) by the atmospheric processes because mineral dust was not acidified beyond the buffer capacity of calcite. In contrast, mineral dust in PM1.3 was acidified beyond the buffer capacity of calcite. As a result, Fesol% in PM1.3 (0.202 %–64.7 %, n=10) was an order of magnitude higher than that in PM>1.3. The PM1.3 contained ferric organic complexes with humic-like substances (Fe(III)-HULIS, but not Fe-oxalate complexes), and the abundance correlated with Fesol%. Iron(III)-HULIS was formed during transport in the Pacific Ocean because Fe(III)-HULIS was not found in aerosol particles in Beijing and Japan. The pH estimations of mineral dust in PM1.3 established that Fe was solubilized by proton-promoted dissolution under highly acidic conditions (pH < 3.0), whereas Fe(III)-HULIS was stabilized under moderately acidic conditions (pH 3.0–6.0). Since the observed labile Fe concentration could not be reproduced by proton-promoted dissolution under moderately acidic conditions, the pH of mineral dust increased after proton-promoted dissolution. The cloud process in the marine atmosphere increases the mineral dust pH because the dust particles are covered with organic carbon and Na. The precipitation of ferrihydrite was suppressed by Fe(III)-HULIS owing to its high water solubility. Thus, the organic complexation of Fe with HULIS plays a significant role in the stabilization of Fe that was initially solubilized by proton-promoted dissolution.

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“…1). More specifically, TOC concentrations are reported to be higher in fog water relative to rain water (Kim et al, 2020), while cloud water solute concentrations exceed those in rain water (Decesari et al, 2005;Gioda et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Total organic carbon and contribution from speciated organics in cloud water: Airborne data analysis from the CAMP<sup>2</sup>Ex field campaign

Stahl¹,

Crosbie²,

Bañaga³

et al. 2021

Preprint

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Abstract. This work focuses on total organic carbon (TOC) and contributing species in cloud water over Southeast Asia using a rare airborne dataset collected during NASA’s Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP2Ex), in which a wide variety of maritime clouds were studied, including cumulus congestus, altocumulus, altostratus, and cumulus. Knowledge of TOC levels and their contributing species is needed for improved modeling of cloud processing of organics and to understand how aerosols and gases impact and are impacted by clouds. This work relies on 159 samples collected with an Axial Cyclone Cloud water Collector at altitudes of 0.2–6.8 km that had sufficient volume for both TOC and speciated organic composition analysis. Species included monocarboxylic acids (glycolate, acetate, formate, and pyruvate), dicarboxylic acids (glutarate, adipate, succinate, maleate, and oxalate), methanesulfonate (MSA), and dimethylamine (DMA). TOC values range between 0.018–13.660 ppm C with a mean of 0.902 ppm C. The highest TOC values are observed below 2 km with a general reduction aloft. An exception is samples impacted by biomass burning for which TOC remains enhanced as high as 6.5 km (7.048 ppm C). Estimated total organic matter derived from TOC contributes a mean of 30.7 % to total measured mass (inorganics + organics). Speciated organics contribute (on carbon mass basis) an average of 30.0 % to TOC in the study region, and account for an average of 10.3 % to total measured mass. The order of the average contribution of species to TOC, in decreasing contribution of carbon mass, is as follows: acetate (14.7 ± 20.5 %), formate (5.4 ± 9.3 %), oxalate (2.8 ± 4.3 %), DMA (1.7 ± 6.3 %), succinate (1.6 ± 2.4 %), pyruvate (1.3 ± 4.5 %), glycolate (1.3 ± 3.7 %), adipate (1.0 ± 3.6 %), MSA (0.1 ± 0.1 %), glutarate (0.1 ± 0.2 %), maleate (< 0.1 ± 0.1 %). Approximately 70 % of TOC remains unaccounted for, thus highlighting the complex nature of organics in the study region; samples collected in biomass burning plumes have up to 95.6 % of unaccounted TOC mass based on the species detected. Consistent with other regions, monocarboxylic acids dominate the speciated organic mass (~75 %) and are about four times in greater abundance than dicarboxylic acids. Samples are categorized into four cases based on back-trajectory history revealing source-independent similarity between the bulk contributions of monocarboxylic and dicarboxylic acids to TOC (16.03 %–23.66 % and 3.70 %–8.75 %, respectively). Furthermore, acetate, formate, succinate, glutarate, pyruvate, oxalate, and MSA are especially enhanced during biomass burning periods, attributed to peat emissions transported from Sumatra and Borneo. Lastly, dust (Ca2+) and sea salt (Na+/Cl−) tracers exhibit strong correlations with speciated organics, thus supporting how coarse aerosol surfaces interact with these water-soluble organics.

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Ship-borne observations of sea fog and rain chemistry over the North and South Pacific Ocean

Cited by 7 publications

References 55 publications

Global modeling of cloud water acidity, precipitation acidity, and acid inputs to ecosystems

Global modeling of cloud water acidity, precipitation acidity, and acid inputs to ecosystems

Iron (Fe) speciation in size-fractionated aerosol particles in the Pacific Ocean: The role of organic complexation of Fe with humic-like substances in controlling Fe solubility

Total organic carbon and contribution from speciated organics in cloud water: Airborne data analysis from the CAMP<sup>2</sup>Ex field campaign

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Ship-borne observations of sea fog and rain chemistry over the North and South Pacific Ocean

Cited by 7 publications

References 55 publications

Global modeling of cloud water acidity, precipitation acidity, and acid inputs to ecosystems

Global modeling of cloud water acidity, precipitation acidity, and acid inputs to ecosystems

Iron (Fe) speciation in size-fractionated aerosol particles in the Pacific Ocean: The role of organic complexation of Fe with humic-like substances in controlling Fe solubility

Total organic carbon and contribution from speciated organics in cloud water: Airborne data analysis from the CAMP&lt;sup&gt;2&lt;/sup&gt;Ex field campaign

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Total organic carbon and contribution from speciated organics in cloud water: Airborne data analysis from the CAMP<sup>2</sup>Ex field campaign