Improved Parameterization of Cloud Droplet Spectral Dispersion Expected to Reduce Uncertainty in Evaluating Aerosol Indirect Effects

Geophysical Research Letters, Journal Year: 2025, Volume and Issue: 52(7)

Published: March 31, 2025

Abstract Relative dispersion ( ε ), as a parameter characterizing droplet spectral shape, exerts considerable impact on cloud radiation and precipitation processes, its accurate parameterization is urgently needed in models. Current parameterizations, which are based number concentration or simply set constants, inadequate to satisfy the demand. This study shows, utilizing in‐situ fog observations from five underlying surface regions (urban, suburban, mountainous, coastal rainforest) of China, that uniformly stably manifests initially increasing then decreasing volume‐mean diameter increases across these regions. Based this relationship, established, exhibits improved predictive capabilities evaluating both albedo effect lifetime effect. The expected enhance simulation accuracy minimize discrepancy between observed simulated precipitation, particularly for weather climate models commonly use double‐moment microphysical schemes.

Language: Английский

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Aircraft Observations Reveal the Relationship Between Cumulus Entrainment Rate and Aerosol Loading

Geophysical Research Letters, Journal Year: 2024, Volume and Issue: 51(19)

Published: Oct. 1, 2024

Abstract The influence of entrainment, a key process characterized by the entrainment rate in cumulus parameterization, on aerosol‐cloud interactions has been widely recognized. However, despite qualitative links established between and aerosol loading, quantitative relationship based observational evidence remains elusive. This study utilizes aircraft observations clouds during two field campaigns to determine loading. In both campaigns, is negatively correlated with It speculated that increased loading enhances cloud edge droplet evaporation, which leads buoyancy vertical velocity within cloud, thereby reducing rate. Further analysis shows response perturbations more significant smaller weak less pronounced under opposite conditions. These findings shed new light improving description parameterizations.

Language: Английский

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Do aerosols induce the differences in low cloud frequency between eastern China and eastern United States?

Atmospheric Research, Journal Year: 2025, Volume and Issue: unknown, P. 107994 - 107994

Published: Feb. 1, 2025

Language: Английский

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Competition response of cloud supersaturation explains diminished Twomey effect for smoky aerosol in the tropical Atlantic

Proceedings of the National Academy of Sciences, Journal Year: 2025, Volume and Issue: 122(13)

Published: March 24, 2025

The Twomey effect brightens clouds by increasing aerosol concentrations, which activates more droplets and decreases cloud supersaturation in response to competition for water vapor. To quantify this response, we used marine low observations clean smoky conditions at Ascension Island the tropical South Atlantic during Layered Aerosol Smoke Interactions with Cloud (LASIC) campaign. These show similar increases droplet number increased accumulation-mode particles from surface-based satellite retrievals, demonstrating importance of below-cloud measurements retrieving aerosol–cloud interactions (ACI) conditions. Four methods estimating were compared, scene-based parcel-based showing sufficient variability a strong dependence on both accumulation concentration cloud-base updraft velocities. Decomposing aerosol-related changes albedo optical depth shows calculated accounts dampening activation 12 35%, explaining diminished high concentrations observed LASIC previously around world. This result was consistent independent retrievals condensation nuclei multimode size-resolving Lagrangian methods. Translating effects local radiative forcing as proxy preindustrial present-day showed that reduces cooling providing an essential process-specific constraint improving representation climate model simulation indirect forcing.

Language: Английский

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Study on the Characteristics and the Parameterization of Effective Radius in Stratiform Precipitation Warm Cloud of Southeastern China Based on WRF‐SBM Simulation

Journal of Geophysical Research Atmospheres, Journal Year: 2024, Volume and Issue: 129(17)

Published: Sept. 4, 2024

Abstract The study on the characteristic and parameterization of cloud droplet effective radius ( r e ) is important for optimization warm microphysical schemes in numerical models. Based simulations combined with four aircraft observations stratiform clouds Jiangxi, China, this work investigated their properties, focusing evolutionary pattern , as well correlation between number concentration N c liquid water path (LWP). It found that there a negative rate decrease could be increased by 2–4 times strengthening collision‐coalescence process. What's more, direct introduction conducted based existing schemes, results show it can perform most intensities. also LWP positively correlated when less than 12 μm, after which relationship changes to due impact rainfall intensity.

Language: Английский

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Numerical simulation of aerosol concentration effects on cloud droplet size spectrum evolutions of warm stratiform clouds in Jiangxi, China

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(23), P. 13525 - 13540

Published: Dec. 9, 2024

Abstract. Changes in aerosol amount and size distribution significantly impact cloud droplet distribution, as aerosols act condensation nuclei (CCNs) influence the relative dispersion (ε) of spectra. Relative plays a key role parameterizing processes general circulation models (GCMs) microphysical schemes, affecting precipitation estimates climate predictions. However, effects varying modes on microphysics remain debated, depending thermodynamic conditions type. This study simulates warm stratiform Jiangxi, China, using Weather Research Forecasting (WRF) Spectra–Bin Microphysics scheme (SBM-FAST) from 18:00 24 December 2014 to 06:00 25 (UTC). Satellite aircraft observations were used validate simulation, showing good agreement structure. Sensitivity experiments conducted by increasing nucleation, accumulation, coarse-mode 5-fold reducing total concentration 1/5 control. Results show that higher concentrations enhance formation broaden spectra, while lower suppress development. Accumulation-mode increase small-droplet concentrations, nucleation- favor larger droplets. The correlation between ε volume-weighted radius (Rv) shifts positive negative Rv increases. transition is driven collision–coalescence, condensation, activation. Increased accumulation-mode shift ε–Rv range 4.5–8 µm, reduced strengthen correlation. Regardless different coalescence intensities, converges with number droplets (Nc).

Language: Английский

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Assessment of the corrected CCN activation parameterizations in simulating shallow cumulus using large-eddy simulations

Atmospheric Research, Journal Year: 2024, Volume and Issue: 315, P. 107881 - 107881

Published: Dec. 22, 2024

Language: Английский

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Aerosol radiation characteristics based on Himawari-8 and AERONET in Beijing city

Journal of Atmospheric and Solar-Terrestrial Physics, Journal Year: 2024, Volume and Issue: unknown, P. 106411 - 106411

Published: Dec. 1, 2024

Language: Английский

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