Understanding aerosol–cloud interactions through modeling the development of orographic cumulus congestus during IPHEx

Duan, Yajuan; Petters, M. D.; Barros, A. P.

doi:10.5194/acp-19-1413-2019

Cited by 8 publications

(14 citation statements)

References 113 publications

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“…The extent of CCN activation is determined based on a chosen slope parameter ( k ) of 0.62 for a moderately polluted cloud over Chennai suggested by Varghese et al (2016). Significantly higher numbers of aerosol droplets activate into cloud droplets (

N_{d}

~ 825 droplets cm −3 ) in the enhanced microphysics case when compared against the standard baseline case with only ~560 droplets cm −3 conforming to the Duan et al (2019) study showing higher cloud droplet numbers with lower values of

α

…”

Section: Resultssupporting

confidence: 71%

“…A recent estimate indicates a solubility range varying from 0.1–0.4 for aged black carbon particles (Ghosh et al, 2007; Yamasoe et al, 2000). A recent paper by Duan et al (2019) have undertaken sensitivity experiments on the effect of condensation coefficient on droplet activation and growth in polluted environments using a cloud parcel model. However, studies related to understanding additional microscale enhancements vis a vis solution non‐ideal consideration along with variable diffusivity values and their implications on cloud morphology are still scanty.…”

Section: Introductionmentioning

confidence: 99%

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An experimental and modelling analysis of cloud droplet growth from vehicular emissions with non‐ideal microphysics over an Asian mega‐city

Gumber

Ghosh

2022

Atmospheric Science Letters

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Large cities in the developing world have unregulated traffic with dysfunctional diesel operated vehicles spewing out copious amounts of micron to sub‐micron sized soot and black carbon particles. These particles mix with other aerosol particles as they are lifted by buoyant eddies. It is shown that the particles are rendered partly soluble as they get coated with soluble sulphate to activate into cloud droplets. This multi‐component aerosol mixture thus comprises of fully soluble as well as partially soluble components so that mass accommodation and diffusional mass transfer considerations need to be carefully quantified over small non‐planar surfaces of aerosol particles sourced from such emissions. The emitted soot and black carbon particles have number concentrations comparable to the sulphate mode and are small enough that the assumption of an infinitely dilute solution droplet is untenable. An X‐ray fluorescence spectrometry indicates the presence of inorganic ions confirming the validity of non‐ideal solution effects warranting a closer look at the osmotic coefficients. Additionally, laboratory values of the binary diffusion coefficients of water vapour cannot be applied to processes operating over the cloud base located several kilometres above where the pressure and temperature are different. A full Lennard‐Jones diffusivity model is used with an accounting of the dipole moment of water vapour which most models ignore. This first study, combining these micro‐scale enhancements are included in a Weather Research and Forecasting (WRF) case study over an Asian city. Not only are significant differences obtained in the cloud morphology when compared to a baseline case, but modelled cloud optical depths agree better with observations.

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N_{d}

α

…”

Section: Resultssupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

An experimental and modelling analysis of cloud droplet growth from vehicular emissions with non‐ideal microphysics over an Asian mega‐city

Gumber

Ghosh

2022

Atmospheric Science Letters

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“…There is no a priori assumption of the particle size distribution. Bin-scheme microphysics is widely used in cloud formation models of Earth's atmosphere and is able to reproduce the multimodal and broad distributions of cloud particles (e.g., Fan et al 2007;Duan et al 2019). Furthermore, CARMA is a non-equilibrium cloud model such that it simulates the time-dependent formation and evolution of cloud particles.…”

Section: Cloud Modelmentioning

confidence: 99%

Transit Signatures of Inhomogeneous Clouds on Hot Jupiters: Insights from Microphysical Cloud Modeling

Powell

Louden

Kreidberg

et al. 2019

ApJ

116

111

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We determine the observability in transmission of inhomogeneous cloud cover on the limbs of hot Jupiters through post processing a general circulation model to include cloud distributions computed using a cloud microphysics model. We find that both the east and west limb often form clouds, but that the different properties of these clouds enhances the limb to limb diffesrences compared to the clear case. Using JWST it should be possible to detect the presence of cloud inhomogeneities by comparing the shape of the transit lightcurve at multiple wavelengths because inhomogeneous clouds impart a characteristic, wavelength dependent signature. This method is statistically robust even with limited wavelength coverage, uncertainty on limb darkening coefficients, and imprecise transit times. We predict that the short wavelength slope varies strongly with temperature. The hot limb of the hottest planets form higher altitude clouds composed of smaller particles leading to a strong rayleigh slope. The near infrared spectral features of clouds are almost always detectable, even when no spectral slope is visible in the optical. In some of our models a spectral window between 5 and 9 microns can be used to probe through the clouds and detect chemical spectral features. Our cloud particle size distributions are not log-normal and differ from species to species. Using the area or mass weighted particle size significantly alters the relative strength of the cloud spectral features compared to using the predicted size distribution. Finally, the cloud content of a given planet is sensitive to a species' desorption energy and contact angle, two parameters that could be constrained experimentally in the future.

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“…The impacts of aerosol species on aerosol water content and CCN spectrum can be effectively predicted based on the revised 𝜅-Köhler theory (Duan et al, 2019;Petters & Kreidenweis, 2007):…”

Section: Methodsmentioning

confidence: 99%

“…It is believed that direct numerical simulation (DNS) is the most complete Eulerian-Lagrangian particle-by-particle-based small-scale model that represents turbulent cloud at the Kolmogorov length scale by considering all cloud particles individually (Bhowmik, Hazra, Rao, & Wang, 2023;Chen et al, 2020;Korolev, 1995). Therefore, it is important to examine the role of aerosol hygroscopicity (𝜅) effects by introducing the revised 𝜅-Köhler theory (Duan et al, 2019;Petters & Kreidenweis, 2007) in small-scale particle-based model. Kawecki and Steiner (2018) have shown the role of aerosol composition on precipitation intensity using the Weather and Research Forecasting (WRF) Model with Chemistry (WRF-Chem).…”

Section: Introductionmentioning

confidence: 99%

The influence of aerosol hygroscopicity on clouds and precipitation over Western Ghats, India

Ray,

Bhowmik,

Hazra

et al. 2024

Quart J Royal Meteoro Soc

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We examine the role of aerosol hygroscopicity (κ) on the formation of clouds and precipitation over the Western Ghats (WG) in India using various numerical model simulations (i.e., particle‐by‐particle‐based small‐scale, high‐resolution mesoscale model). For the diffusional growth of cloud droplets, the size‐dependent hygroscopicity is used in the κ‐Köhler equation of direct numerical simulation. The results of the small‐scale model reveal that the distribution of cloud drop size varies from the initial mixing state to the well‐mixed state due to variation in κ. The value of κ is obtained from Humidified Tandem Differential Mobility Analyzer (HTDMA) instruments at the High Altitude Cloud Physics Laboratory, India. The idealized and real simulations using the Weather and Research Forecasting (WRF) model with the aerosol‐aware Thompson microphysics scheme are conducted by changing κ values. Depending on the type of clouds (shallow or deep), different κ values determine the mass and number of cloud and rain droplets. Low hygroscopicity (organics) simulates more and smaller drops, as well as uplifts below freezing level, resulting in more ice‐phase hydrometeors. Organic aerosols have a significant impact on the formation of more snow and graupel hydrometeors. As compared to high κ, low hygroscopicity weakens updrafts at the intermediate level and strengthens them at the upper level in the deep cloud region. The intensity of precipitation varies due to low and high κ. The findings indicate that aerosol composition has a significant impact on the activation of cloud condensation nuclei. This study suggests that aerosol hygroscopicity is essential in weather prediction models to integrate aerosol chemical compositions.

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Understanding aerosol–cloud interactions through modeling the development of orographic cumulus congestus during IPHEx

Cited by 8 publications

References 113 publications

An experimental and modelling analysis of cloud droplet growth from vehicular emissions with non‐ideal microphysics over an Asian mega‐city

An experimental and modelling analysis of cloud droplet growth from vehicular emissions with non‐ideal microphysics over an Asian mega‐city

Transit Signatures of Inhomogeneous Clouds on Hot Jupiters: Insights from Microphysical Cloud Modeling

The influence of aerosol hygroscopicity on clouds and precipitation over Western Ghats, India

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