More Like this

1. Modelling the effects of atmospheric alkylamines on the properties of sea salt aerosols using the extended aerosols and inorganics model (E-AIM)

   Chen, K.; Zhang, K.; Qiu, C. (August 2021, The 262nd American Chemical Society National Meeting & Exposition)

   Sea salt aerosols contribute significantly to the mass loading of ambient aerosol, which may serve as cloud condensation nuclei and can contribute to light scattering in the atmosphere. Two major chemical components commonly found in sea salts are ammonium sulfate (AS) and sodium chloride (NaCl). It has been shown that alkylamines, derivatives of ammonia, can react with ammonium salts in the particle-phase to displace ammonia and likely change the particle properties. This study investigated the effects of atmospheric alkylamines on the composition and properties of sea salt aerosols using a chemical system of methylamine (MA, as a proxy of alkylamines), AS and NaCl (as a proxy of sea salt aerosol). The concentrations of ammonia and MA in aqueous/gas phases at the thermodynamic equilibrium were determined using the Extended Aerosols and Inorganics Model (E-AIM) under varying initial inputs, along with the deliquescence relative humidity (DRH) and the corresponding particle water content. Our findings indicated a notable negative relationship between MA concentration and the DRH for both AS and NaCl while the effect of MA on NaCl is smaller than that on AS. The salt of MA in the particle phase may absorb water vapor and may lead to the displacement reaction between AS and NaCl due to the low solubility of sodium sulfate. The acidity in the particle phase also played a significant role in affecting the DRH of sea salt aerosols. Since both sea salt aerosol and alkylamines are emitted into the atmosphere from the ocean in large quantities, our study suggested the potential impact of alkylamines on the environment and the climate via the modification of sea salt aerosol properties. 

   more » « less
2. Effects of particle phase acidity and gaseous ammonia on the heterogenous interactions between amines and ambient aerosol

   Hang, Y.-J.; Newberry, C.; DeMayo, R.; Qiu, C. (August 2021, The 262nd American Chemical Society National Meeting & Exposition)

   Recent research in atmospheric chemistry suggested that gaseous amines may rapidly react with the acidic components in the aerosol to be incorporated in the particle phase. However, laboratory experiments suggested that these heterogeneous processes may be sensitive to the reaction conditions, such as relative humidity (RH), the initial aerosol acidity and the initial concentration of gaseous ammonia which is ubiquitous in the atmosphere. We studied the heterogenous reactions between several amines and ammonium sulfate using a series of thermodynamic simulations under varying initial conditions, including RH, particle-phase acidity and gaseous amine and ammonia concentrations. Several distinctively different trends in the particle-phase ammonium, amines and water content were observed, depending significantly on the particle-phase acidity and the initial amine to ammonia mole ratio. One notable observation was that alkylamines may facilitate the water uptake of ammonium sulfate even in the presence of 1000 times more ammonia gas. Such change in aerosol water content may alter the surface tension, uptake coefficient and could formation properties of aerosol and influence the radiative forcing of the particles. 

   more » « less
3. Efficient In‐Cloud Removal of Aerosols by Deep Convection

   https://doi.org/10.1029/2018GL080544  

   Yu, Pengfei; Froyd, Karl D.; Portmann, Robert W.; Toon, Owen B.; Freitas, Saulo R.; Bardeen, Charles G.; Brock, Charles; Fan, Tianyi; Gao, Ru‐Shan; Katich, Joseph M.; et al (January 2019, Geophysical Research Letters)

   Abstract Convective systems dominate the vertical transport of aerosols and trace gases. The most recent in situ aerosol measurements presented here show that the concentrations of primary aerosols including sea salt and black carbon drop by factors of 10 to 10,000 from the surface to the upper troposphere. In this study we show that the default convective transport scheme in the National Science Foundation/Department of Energy Community Earth System Model results in a high bias of 10–1,000 times the measured aerosol mass for black carbon and sea salt in the middle and upper troposphere. A modified transport scheme, which considers aerosol activation from entrained air above the cloud base and aerosol‐cloud interaction associated with convection, dramatically improves model agreement with in situ measurements suggesting that deep convection can efficiently remove primary aerosols. We suggest that models that fail to consider secondary activation may overestimate black carbon's radiative forcing by a factor of 2. 

   more » « less
4. Arctic warming by abundant fine sea salt aerosols from blowing snow

   https://doi.org/10.1038/s41561-023-01254-8  

   Gong, Xianda; Zhang, Jiaoshi; Croft, Betty; Yang, Xin; Frey, Markus M.; Bergner, Nora; Chang, Rachel Y. -W.; Creamean, Jessie M.; Kuang, Chongai; Martin, Randall V.; et al (September 2023, Nature Geoscience)

   Abstract The Arctic warms nearly four times faster than the global average, and aerosols play an increasingly important role in Arctic climate change. In the Arctic, sea salt is a major aerosol component in terms of mass concentration during winter and spring. However, the mechanisms of sea salt aerosol production remain unclear. Sea salt aerosols are typically thought to be relatively large in size but low in number concentration, implying that their influence on cloud condensation nuclei population and cloud properties is generally minor. Here we present observational evidence of abundant sea salt aerosol production from blowing snow in the central Arctic. Blowing snow was observed more than 20% of the time from November to April. The sublimation of blowing snow generates high concentrations of fine-mode sea salt aerosol (diameter below 300 nm), enhancing cloud condensation nuclei concentrations up to tenfold above background levels. Using a global chemical transport model, we estimate that from November to April north of 70° N, sea salt aerosol produced from blowing snow accounts for about 27.6% of the total particle number, and the sea salt aerosol increases the longwave emissivity of clouds, leading to a calculated surface warming of +2.30 W m⁻²under cloudy sky conditions. 

   more » « less
5. Organic Acids In Cloud Water, Aerosols And Cloud Droplet Residuals at the Summit Of Whiteface Mountain (WFM)

   Tripathy, A; Lawrence, C; Casson, P; Lombardo, S; Patel, R; Hammond, L; Brandt, R; McKim, S; Schlemmer, J; Khwaja, H; et al (October 2024, American Association for Aerosol Research)

   Organic compounds in the atmosphere play a pivotal role in atmospheric chemistry, and clouds are significant in the genesis and alteration of these compounds. Di-carboxylic organic anions such as oxalate serve as tracers for aqueous processing. This poster details our findings from summer measurements of three major organic acids (formic acid, acetic acid, oxalic acid), as well as inorganic anions (sulfate, chloride, nitrate) and cations (sodium, potassium, ammonium, calcium, magnesium) in cloud water, aerosol, and cloud droplet residual samples collected at the summit of Whiteface Mountain (WFM) in the Adirondack Mountains, northern New York State. We also evaluate the contribution of these organic acids to water-soluble organic carbon (WSOC) concentrations. Previous studies have explored the oxalate: WSOC ratio with ozone levels, aiming to deduce the influence of biogenic Volatile Organic Compounds (VOCs) on Secondary Organic Aerosol (SOA) formation from nearby forest ecosystems. Our poster presents new observations that significantly broaden this understanding by comparing to diverse global environments and analyzing both cloud water and aerosol phases. Additionally, we introduce oxalate: sulfate ratios from our dataset, proposed by other researchers as a key indicator of aqueous processing due to the enhanced production rates of these ions by liquid water content (sulfate ion) or droplet surface area (oxalate ion). We compare the observed range of oxalate: sulfate ratios with those from field campaigns conducted in other regions. Moreover, for the first time, we examine the relationship between ammonium and organic acids across cloud water, aerosol, and droplet residual samples collected in 2023, and discuss the influence of wildfire smoke on these dynamics. 

   more » « less