Aerosol Activation in Radiation Fog at the Atmospheric Radiation Program Southern Great Plains Site

Wainwright, Charlotte E.; Chang, Rachel Y.-­W.; Richter, David H.

doi:10.1029/2021jd035358

Cited by 6 publications

(4 citation statements)

References 72 publications

(173 reference statements)

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“…The evolutions of estimated supersaturations during the fog episode on 11‐04 are also shown in Figure 2b, indicating that supersaturation reached a peak of approximately 0.034% after about 2 hr of fog initiation, remained steady for approximately 1 hr, and then gradually decreased until fog dissipation. The estimated peak supersaturation of 0.034% is in line with values reported in Europe (Boutle et al., 2018; Hammer et al., 2014; Mazoyer et al., 2019), China (Shen et al., 2018), and North America (Wainwright et al., 2021), further confirming the low supersaturation characteristics of fogs globally.…”

Section: Resultssupporting

confidence: 84%

“…Lower supersaturation values correspond to larger critical activation diameters. Previous research on fog activation has revealed the typically low supersaturation conditions of fogs, often below 0.1% (Boutle et al., 2018; Shen et al., 2018; Wainwright et al., 2021). This low supersaturation environment makes it challenging to clearly differentiate between activated and non‐activated aerosols.…”

Section: Field Measurements and Methodsmentioning

confidence: 99%

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Divergent Impacts of Biomass Burning and Fossil Fuel Combustion Aerosols on Fog‐Cloud Microphysics and Chemistry: Novel Insights From Advanced Aerosol‐Fog Sampling

Kuang,

Xu,

Tao

et al. 2024

Geophysical Research Letters

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Activation of biomass burning aerosols (BBA) and fossil fuel combustion aerosols (FFA) in fogs and clouds significantly impact regional air quality through aqueous chemistry and climate by affecting cloud microphysics. However, we lack direct observations of how these aerosols behave in fogs and clouds. Using a newly developed aerosol‐cloud sampling system, we conducted observations during fog events and found that BBA, despite their high organic content, effectively contributed to super‐micron interstitial aerosols and fog droplets in low supersaturation fogs. In contrast, FFA, predominantly externally mixed organic, did not grow beyond the super‐micron size in fogs due to their near‐hydrophobic nature. Measurements conducted under supersaturations relevant for cloud formation revealed that portions of FFA could serve as cloud condensation nuclei, but only when supersaturation exceeded ∼0.14%. These findings have broad implications for future investigations into the influence of BBA and FFA on fog and cloud chemistry and their interactions with clouds.

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Section: Resultssupporting

confidence: 84%

Section: Field Measurements and Methodsmentioning

confidence: 99%

Divergent Impacts of Biomass Burning and Fossil Fuel Combustion Aerosols on Fog‐Cloud Microphysics and Chemistry: Novel Insights From Advanced Aerosol‐Fog Sampling

Kuang,

Xu,

Tao

et al. 2024

Geophysical Research Letters

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“…Considering the shattered particles and interstitial aerosols (i.e., unactivated particles), fog droplets were identified to be greater than 2 μm in diameter, and fog with N f

{\ge}

10 cm −3 and LWC

{\ge}

1 mg m −3 was identified (Lu et al., 2020; Wang, Niu, et al., 2021), which is the same as the criterion of cloud identification (e.g., Deng et al., 2009; Yang et al., 2019; Zhao et al., 2019). It should be noted that interstitial aerosols could still be present in the FDSD, particularly in the small droplet size (Shen et al., 2018; Mazoyer et al., 2019; Wainwright et al., 2021). As shown in Table 1, eight fog cases with 88,962 FDSDs were identified.…”

Section: Methodsmentioning

confidence: 99%

Diverse Dispersion Effects and Parameterization of Relative Dispersion in Urban Fog in Eastern China

Wang

Niu

et al. 2023

JGR Atmospheres

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Understanding cloud droplet relative dispersion is critical for mitigating the confounding effect of aerosol‐cloud interactions in the simulation of the global climatic patterns. Diverse dispersion effects, meaning that the correlation between relative dispersion (ε) and fog droplet number concentration (Nf) changes from positive to negative as Nf increases at a fixed liquid water content (LWC) condition, were found in the urban fog observed during the winters of 2017 and 2018 in Nanjing, China. The dominant microphysical processes driving the diverse dispersion effects were found to be activation, condensation, deactivation, evaporation, and sedimentation. The critical first bin (diameter range of 2–4 μm) strength and volume‐mean diameter (Dv) for classifying the diverse dispersion effects are 0.3–0.4 and 10–12 μm, respectively. The mean dispersion offset (DO) was −27.6% for weakening the Twomey effect and 27.5% for enhancing it. Assuming the Gamma distribution for the fog droplet number size distribution, the mean dispersion effect was significantly underestimated at DO < 0. Based on the measured nonmonotonic relationship between ε and Dv, we establish ε parameterization using a Nelder function, which can be applied to the diverse dispersion effects. The mean deviation for diagnosing DO was less than 10% for DO > 0 and less than 50% for DO < 0. These results could shed new light on understanding the diverse dispersion effects, which cloud help reduce the uncertainties in the simulation of aerosol‐cloud interactions.

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“…Thereto, CCN could activate into fog droplets, leading to an increase in N, especially for the small droplets. It should be noted that the interstitial aerosols could contribute significantly to N (Shen et al, 2018;Mazoyer et al, 2019;Wainwright et al, 2021), because of the generally low supersaturation in fogs and relatively high aerosol loading in this region. After 5:15 a.m. (beginning of the mature phase), the continuous activation (Devenish et al, 2012) and condensation processes caused a significant fog droplets number concentration at each stage.…”

Section: Fog Scavenging Effectsmentioning

confidence: 99%

Chemical characteristics of three-stage fog water in an agricultural city in China

Fan

Wang

et al. 2022

Front. Environ. Sci.

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To investigate the relationships among the chemical compositions of fog droplets, atmospheric pollutants, and the fog microphysical characteristics, four fog cases were sampled in a comprehensive field experiment conducted at the Donghai site in an agricultural city, China, in the winter of 2020. The pH, electrical conductivity (EC), total ion concentration (TIC), and chemical compositions of the fog water were all size-dependent. High concentrations of non-sea-salt calcium (nssCa2+) and NH4+ led to the alkaline pH of 6.13–7.32. The TIC of fog water was relatively high, especially in small droplets of diameter within 4–16 μm (463527.9 μeq/L). The relatively high NO2− concentration was also found in the fog water, dominated by the non-homogeneous chemical reaction between NO2 and fog droplets. An interesting finding is that the TIC of fog water measured on December 12 was much higher than that measured on December 11. Compared to the first fog, the stronger thermal inversion and local emissions led to the higher concentration of atmospheric particles in the second fog. Generally, the relatively high concentration of atmospheric particles resulted in a large number of small-sized droplets, which had fast liquid-phase oxidation reaction rates and high gas-liquid conversion efficiencies, leading to a higher TIC in the fog water during the second fog.

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Aerosol Activation in Radiation Fog at the Atmospheric Radiation Program Southern Great Plains Site

Cited by 6 publications

References 72 publications

Divergent Impacts of Biomass Burning and Fossil Fuel Combustion Aerosols on Fog‐Cloud Microphysics and Chemistry: Novel Insights From Advanced Aerosol‐Fog Sampling

Divergent Impacts of Biomass Burning and Fossil Fuel Combustion Aerosols on Fog‐Cloud Microphysics and Chemistry: Novel Insights From Advanced Aerosol‐Fog Sampling

Diverse Dispersion Effects and Parameterization of Relative Dispersion in Urban Fog in Eastern China

Chemical characteristics of three-stage fog water in an agricultural city in China

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