Anelastic Convective Entities: formulation and properties DOI Open Access
Yi‐Hung Kuo, J. David Neelin

Authorea (Authorea), Journal Year: 2023, Volume and Issue: unknown

Published: Nov. 8, 2023

A formulation based on the anelastic approximation yields time-dependent simulations of convective updrafts, downdrafts and other aspects convection-such as stratiform layers-under reasonably flexible geometry assumptions. Termed entities (ACEs), such realizations can aid understanding processes, potentially provide building blocks for parameterization at a complexity between steady-plume models cloud-resolving simulations. Even cases deliberately formulated to comparison traditional plume, ACE behavior differs substantially because dynamic entrainment, detrainment nonhydrostatic perturbation pressure are consistently included. Entrainment varies with evolution entity but akin deep-inflow effects noted in observations emerges naturally. The magnitude mass flux nonlocal included is smaller than corresponding model. solutions do not necessarily approach steady state even fixed environment exhibit chains rising thermals, episodic deep convection. inclusion dynamics allows developing updraft tunnel through layers substantial inhibition (CIN). For nighttime continental convection using GoAmazon soundings, this found greatly reduce effect surface-inversion CIN. observed cold top seen an inherent property solution, both transient, phase persistent feature mature An embedded configuration cloud formation by modified feedbacks during grid-scale adjustment process. SIGNIFICANCE STATEMENT: Convective storms cause hazardous events flooding, often economic losses. Forecasting how they change warming climate mitigation planning hard. In modern numerical weather models, one issue standing out that model cannot satisfactorily simulate over land commonly over, instance, North American Great Plains or Amazon basin. Here, we propose new model-named (ACE)-with two purposes mind: (i) be useful improving models; (ii) help understand processes general. Preliminary results covered here promising, especially problem.

Language: Английский

Competition response of cloud supersaturation explains diminished Twomey effect for smoky aerosol in the tropical Atlantic DOI Creative Commons
Jeramy L. Dedrick,

Christian Pelayo,

Lynn M. Russell

et al.

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

Citations

0
Shallow Cumulus Properties as Captured by Adiabatic Fraction in High-Resolution LES Simulations DOI Creative Commons
Eshkol Eytan, А. Хаин,

Mark Pinsky

et al.

Journal of the Atmospheric Sciences, Journal Year: 2021, Volume and Issue: 79(2), P. 409 - 428

Published: Nov. 17, 2021

Abstract Shallow convective clouds are important players in Earth’s energy budget and hydrological cycle, abundant the tropical subtropical belts. They greatly contribute to uncertainty climate predictions due their unresolved, complex processes that include coupling between dynamics microphysics. Analysis of cloud structure can be simplified by considering motions as a combination moist adiabatic like updrafts turbulent leading deviation from adiabaticity. In this work, we study sizes occurrence regions shallow cumulus during growth mature stages, use fraction (AF) continuous metric describe properties core edge. To do so, simulate isolated trade wind different using System Atmospheric Modeling (SAM) model high resolution (10 m) with Hebrew University spectral bin microphysics (SBM). The fine features clouds’ microphysics, including small near-adiabatic volumes thin transition zone at edge (∼20–40 m width), captured. AF is shown an efficient measure for analyzing key determining droplet-size distribution formation shape evolution. Physical governing droplet size distributions (e.g., core, edge) analyzed relation AF. Significance Statement 1) This investigates evolution (Cu) 10-m-resolution LES 2) improves understanding mutual effects lateral entrainment mixing. 3) demonstrates existence nonprecipitating Cu. 4) Shapes closely related values. 5) Utilization reveals physically significant structure, such narrow interface volumes.

Language: Английский

Citations

27
Unveiling the effects of post-monsoon agricultural biomass burning on aerosols, clouds, and radiation in Northwest India DOI Creative Commons
Pradeep Khatri, Tadahiro Hayasaka, Prabir K. Patra

et al.

Progress in Earth and Planetary Science, Journal Year: 2025, Volume and Issue: 12(1)

Published: Feb. 5, 2025

Language: Английский

Citations

0
The Importance of Humidity in the Afternoon Local-Scale Precipitation Intensity over Eastern China and Its Impacts on the Aerosol Effects DOI Creative Commons

Xiaogang Tang,

Qian Chen, Jianping Guo

et al.

Remote Sensing, Journal Year: 2025, Volume and Issue: 17(5), P. 778 - 778

Published: Feb. 23, 2025

Thermally driven local-scale precipitation (LSP) is an important type of summer over China, but the prestorm environmental conditions remain unclear. In order to investigate major factors controlling LSP intensity, meteorological parameters preceding occurrence light and heavy afternoon Eastern China during 2018–2022 are examined using rain gauge, radiosonde sounding, satellite observations. The temperature differences between events relatively small, exhibit larger water vapor mixing ratios (Qv) below a 5 km altitude than LSP. With almost identical vertical distribution, increment in Qv increases relative humidity (RH) lower troposphere. Furthermore, large eddy simulations with spectral bin microphysics performed impacts aerosols on intensity. Increased low-level RH leads mass concentrations graupel at expense cloud droplets due enhanced drop collisions riming ice particles, respectively, thereby reinforcing However, increased aerosol concentration more reduced content, resulting mainly from suppressed collisions. ratio exhibits non-monotonic trend aerosols, mostly contributed by riming. As result, intensity first then decreases both dry humid air. Moreover, lead humidification surrounding air evaporation droplets, particularly under lower-RH conditions. These findings provide understanding effects covariations China.

Language: Английский

Citations

0
Are turbulence effects on droplet collision–coalescence a key to understanding observed rain formation in clouds? DOI Creative Commons
Kamal Kant Chandrakar, Hugh Morrison, Wojciech W. Grabowski

et al.

Proceedings of the National Academy of Sciences, Journal Year: 2024, Volume and Issue: 121(27)

Published: June 25, 2024

Rain formation is a critical factor governing the lifecycle and radiative forcing of clouds therefore it key element weather climate. Cloud microphysics–turbulence interactions occur across wide range scales are challenging to represent in atmospheric models with limited resolution. Based on past experiments idealized numerical simulations, has been postulated that cloud turbulence accelerates rain by enhancing drop collision–coalescence. We provide substantial evidence for significant impacts evolution droplet size distributions comparing high-resolution observations cumulus congestus state-of-the-art large-eddy simulations coupled Lagrangian particle-based microphysics scheme. Turbulent coalescence must be included model accurately observed distributions, especially drizzle sizes at lower heights cloud. Turbulence causes earlier greater accumulation compared gravitational only. The distribution tail just above base follows power law scaling deviates from theoretical scalings considering either purely gravitation collision kernel or turbulent neglecting inertial effects, providing additional clouds. In contrast, large aerosols acting as condensation nuclei (“giant CCN”) do not significantly impact owing their long timescale reach equilibrium wet relative lifetime rising thermals. Overall, exerts dominant influence initiation warm clouds, giant CCN.

Language: Английский

Citations

3
Observed and Simulated Variability of Droplet Spectral Dispersion in Convective Clouds Over the Amazon DOI
Lianet Hernández Pardo, Luiz A. T. Machado, Hugh Morrison

et al.

Journal of Geophysical Research Atmospheres, Journal Year: 2021, Volume and Issue: 126(20)

Published: Sept. 23, 2021

Abstract In this study, the variability of spectral dispersion droplet size distributions (DSDs) in convective clouds is investigated. Analyses are based on aircraft measurements growing cumuli near Amazon basin, and numerical simulations an idealized ice‐free cumulus. cleaner clouds, relative , defined as ratio standard deviation to mean value diameter, negatively correlated with cloud water content ( ) adiabatic liquid ), while no strong correlation between seen polluted clouds. Bin microphysics suggest that these contrasting behaviors associated effect collision‐coalescence secondary activation addition turbulent mixing parcels experienced different paths within cloud. Collision‐coalescence simultaneously broadens DSDs decreases explaining inverse relationship Secondary but has little direct impact . The combination a rather modest DSD broadening due weak enhanced both diluted highly undiluted regions may contribute maintain relatively uniform These findings can be useful for parameterizing shape parameter gamma bulk cloud‐resolving models. It shown emulating observed improves estimation rate compared bin simulations.

Language: Английский

Citations

16
Increased aerosols can reverse Twomey effect in water clouds through radiative pathway DOI Creative Commons
Pradeep Khatri, Tadahiro Hayasaka, B. N. Holben

et al.

Scientific Reports, Journal Year: 2022, Volume and Issue: 12(1)

Published: Nov. 30, 2022

Abstract Aerosols play important roles in modulations of cloud properties and hydrological cycle by decreasing the size droplets with increase aerosols under condition fixed liquid water path, which is known as first aerosol indirect effect or Twomey-effect microphysical effect. Using high-quality data from surface observations statistically decoupling influence meteorological factors, we show that highly loaded can counter this through radiative to result both decrease droplet depending on path clouds. The due increased reduces moisture content, but increases atmospheric stability at higher altitudes, generating conditions favorable for top entrainment coalescence. Such radiatively driven coalescence process relatively stronger thicker clouds weaker effect, resulting loading; vice-versa thinner Overall, study suggests prevalence negative positive relationships between loading polluted regions.

Language: Английский

Citations

11
Between Broadening and Narrowing: How Mixing Affects the Width of the Droplet Size Distribution DOI Creative Commons
Jung‐Sub Lim, Fabian Hoffmann

Journal of Geophysical Research Atmospheres, Journal Year: 2023, Volume and Issue: 128(8)

Published: March 31, 2023

Abstract Entrainment and mixing play an essential role in shaping the droplet size distribution (DSD), with commensurate effects on cloud radiative properties or precipitation formation. In this paper, we use a model that considers all relevant scales related to entrainment by employing linear eddy (LEM) as subgrid‐scale (SGS) model, coupled large‐eddy simulation Lagrangian (LCM) for single cumulus congestus cloud. We confirm DSD is broadened toward small‐size droplets during homogeneous mixing. During inhomogeneous mixing, width remains almost unchanged. The can also be narrowed after show happens when droplets, which evaporate rapidly, while larger are unaffected. addition, ascend narrowing caused adiabatic increase supersaturation slower than average evaporation, allowing only largest benefit from newly produced supersaturation. scenario prevents clouds having too broad DSDs causes relative dispersion converge around 0.2 0.4. As more frequent LEM SGS used, our results indicate adequately modeling turbulent necessary represent realistic shape.

Language: Английский

Citations

6
Modulation of fluid temperature fluctuations by particles in turbulence DOI Creative Commons
Izumi Saito, Takeshi Watanabe, Toshiyuki Gotoh

et al.

Journal of Fluid Mechanics, Journal Year: 2021, Volume and Issue: 931

Published: Nov. 22, 2021

Modulation of fluid temperature fluctuations by particles due to thermal interaction in homogeneous isotropic turbulence is studied. For simplicity, only coupling between the and considered, momentum neglected. Application statistical theory used cloud research leads prediction that modulation intensity expressed as a function Damköhler number, which defined ratio large-eddy turnover time relaxation time. Direct numerical simulations are conducted for two-way field point turbulence. The simulation results shown agree well with theoretical predictions.

Language: Английский

Citations

13
Observed and Bin Model Simulated Evolution of Drop Size Distributions in High‐Based Cumulus Congestus Over the United Arab Emirates DOI
Hugh Morrison, R. Paul Lawson, Kamal Kant Chandrakar

et al.

Journal of Geophysical Research Atmospheres, Journal Year: 2022, Volume and Issue: 127(3)

Published: Jan. 7, 2022

Abstract This study examines microphysical processes in developing high‐based cumulus congestus over the United Arab Emirates using aircraft observations and a large‐eddy‐simulation model with bin microphysics. A notable feature of this case is lack mm‐sized drops despite having liquid cloud layer km deep, contrasting copious large observed maritime tropical similar vertical extent. Modeled drop size distributions are to at various temperatures between 9.5 −12°C, including drops. Cloud dilution leads low‐to‐moderate water contents (∼0.5–1.5 g m −3 ) most core, several times smaller than adiabatic values. Dilution enhanced inflowing branch toroidal circulations associated individual thermals, which favored regions for secondary droplet activation (activation above base). Secondary general contributes substantially population. Turning it off sharp decrease concentration increase mean aloft, but does little rain production. Warm generation (or thereof) therefore determined more by sub‐cloud aerosol base distribution (DSD) DSD evolution aloft from activation. Decreasing factor 10 greatly increases production via collision‐coalescence. Thus, its high (low temperatures) substantial dilution, simulated thermodynamically dynamically capable rapidly producing collision‐coalescence under pristine conditions.

Language: Английский

Citations

9