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

Aerosol Effects on Water Cloud Properties in Different Atmospheric Regimes DOI Creative Commons
Pradeep Khatri, Kazuya Yoshida, Tadahiro Hayasaka

et al.

Journal of Geophysical Research Atmospheres, Journal Year: 2023, Volume and Issue: 128(24)

Published: Dec. 9, 2023

Abstract Aerosol‐cloud interaction remains one of the least understood processes in climate science arena, despite its profound impacts radiation and water budget perturbations. The aerosol effects on clouds largely depend characteristics. Here, we implemented 17‐year (2003–2020) data set aerosol, cloud, meteorological factors collected over East Asia—a highly polluted region with recent decreasing trend air pollution due to control measures—to elucidate atmospheric regime‐dependent cloud properties by simultaneously accessing response measures field. study found a very close relationship between loading modifications continental Asia significant further revealed that aerosols atmosphere affected micro‐ macro‐physics differently than clean maritime atmosphere: former, increased stability under base then enhanced droplet collision‐coalescence process, resulting increase size top height; whereas latter, decreased without notable influence thermodynamics height. This showed complex aerosol‐cloud process mixed effect atmospheres. In all regimes, fraction was loading.

Language: Английский

Citations

5
Impact of Cloud-Base Turbulence on CCN Activation: Single-Size CCN DOI
Wojciech W. Grabowski, Lois Thomas, Bipin Kumar

et al.

Journal of the Atmospheric Sciences, Journal Year: 2021, Volume and Issue: 79(2), P. 551 - 566

Published: Dec. 6, 2021

Abstract This paper examines the impact of cloud-base turbulence on activation cloud condensation nuclei (CCN). Following our previous studies, we contrast within a nonturbulent adiabatic parcel and an filled with turbulence. The latter is simulated by applying forced implicit large-eddy simulation triply periodic computational domain 64 3 m . We consider two monodisperse CCN. Small CCN have dry radius 0.01 μ corresponding (critical) critical supersaturation 0.6 1.3%, respectively. Large 0.2 feature 5.4 0.15%. are assumed in 200-cm −3 concentration all cases. Mean updraft velocities 0.33, 1, s −1 considered. In parcel, activated lead to droplet size distribution above base, practically same simulations. contrast, can only fraction nonzero spectral width order 1 m, especially case small weak mean ascent. compare results studies turbulent single-size Pi chamber. Sensitivity simulations that apply smaller intensity, domain, modified initial conditions document specific modeling assumptions. call for more realistic high-resolution activation.

Language: Английский

Citations

12
Supersaturation Variability from Scalar Mixing: Evaluation of a New Subgrid-Scale Model Using Direct Numerical Simulations of Turbulent Rayleigh–Bénard Convection DOI
Kamal Kant Chandrakar, Hugh Morrison, Wojciech W. Grabowski

et al.

Journal of the Atmospheric Sciences, Journal Year: 2022, Volume and Issue: 79(4), P. 1191 - 1210

Published: Jan. 28, 2022

Abstract Supersaturation fluctuations in the atmosphere are critical for cloud processes. A nonlinear dependence on two scalars—water vapor and temperature—leads to different behavior than single scalars turbulent convection. For modeling such multiscalar processes at subgrid scales (SGS) large-eddy simulations (LES) or convection-permitting models, a new SGS scheme is implemented CM1 that solves equations water temperature their covariance. The model evaluated using benchmark direct-numerical (DNS) of Rayleigh–Bénard convection with as Michigan Tech Pi Cloud Chamber. This idealized setup allows thorough evaluation without complications from other atmospheric DNS results compare favorably measurements chamber. Results LES well DNS, including profiles variances, covariance, supersaturation variance. scale appropriately changes grid spacing, magnitude decreasing relative those resolved spacing decreased. Sensitivities covariance statistics flux thermal also investigated by modifying sidewall conditions. Relative substantially decrease increase even away boundaries.

Language: Английский

Citations

8
Anelastic Convective Entities. Part 2: Adjustment processes and convective cold top DOI Open Access
Yi‐Hung Kuo, D. Jérôme

Authorea (Authorea), Journal Year: 2024, Volume and Issue: unknown

Published: June 10, 2024

Seeking a family of models filling the hierarchy between steady plumes and cloud-resolving simulations, Part I this study presented formulation termed anelastic convective entities (ACEs). The solution includes pressure-mediated nonlocal effects in both vertical horizontal thus yields time-dependent simulations updrafts, downdrafts other aspects convection even for single column interacting with fixed environment through dynamically determined inflow outflow. Here we show how straightforward iteration that can capture interactions among variety choices geometry interactions. Using an oceanic sounding to contrast land cases 1, first illustrate ACE exhibit ongoing evolution depending, e.g., on parameterized turbulence. For case which would yield near-steady deep-convective state, examine adjustment process multi-ACE prototype within climate model grid cell. This embedded configuration exhibits stratiform cloud expansion outflow modified by dynamic feedbacks. grid-scale not only traditional warming large-scale descent, but also captures spread cold top. illustrates possibility multi-hour time lag before transition deep convection, remote initiation small velocities grid-cell environment. Comparing 1-, 2-, 4-and 8-ACE instances suggests promise as potential convective-parameterization class traditional-and super-parameterization, while providing sandbox aid understanding processes.

Language: Английский

Citations

1
Life Cycle Evolution of Mixing in Shallow Cumulus Clouds DOI Creative Commons
Jung‐Sub Lim, Fabian Hoffmann

Journal of Geophysical Research Atmospheres, Journal Year: 2024, Volume and Issue: 129(10)

Published: May 18, 2024

Abstract Understanding how entrainment and mixing shape the cloud droplet size distribution (DSD) is crucial for understanding optical properties precipitation efficiency of clouds. Different scenarios, mainly homogeneous inhomogeneous, DSD in a distinct way alter cloud's impact on climate. However, prevalence these scenarios they vary space time still uncertain, as underlying processes are commonly unresolved by conventional numerical models. To overcome this challenge, we employ L 3 model, which considers supersaturation fluctuations turbulent down to finest relevant lengthscales, making it possible represent different realistically. We investigate spatial temporal evolution over life cycle shallow cumulus clouds varying boundary layer humidities aerosol concentrations. Our findings suggest generally predominant clouds, while occur concurrently same cloud. Notably, inhomogeneous increases across all analyzed cases. The mean standard deviation found be most capable indicators evolution, providing comprehensive insight into characteristics scenarios. Finally, show more prevalent drier layers higher concentrations, underscoring need investigation dynamics evolve changing

Language: Английский

Citations

1
What Controls Crystal Diversity and Microphysical Variability in Cirrus Clouds? DOI Creative Commons
Kamal Kant Chandrakar, Hugh Morrison, Jerry Y. Harrington

et al.

Geophysical Research Letters, Journal Year: 2024, Volume and Issue: 51(11)

Published: June 5, 2024

Abstract Variability of ice microphysical properties like crystal size and density in cirrus clouds is important for climate through its impact on radiative forcing, but challenging to represent models. For the first time, recent laboratory experiments particle growth (tied morphology via deposition density) are combined with a state‐of‐the‐art Lagrangian particle‐based microphysics model large‐eddy simulations examine sources variability cirrus. Simulated distributions compare well against balloon‐borne observations. Overall, dominated by particles' thermodynamic histories. However, diversity notably increases spatial mean density, especially at mid‐levels cloud. Little correlation between instantaneous supersaturation occurs even though modeled directly tied based measurements. Thus, individual paths each particle, not conditions, control evolution properties.

Language: Английский

Citations

1
Entrainment rates in the cloud zones of continental shallow cumulus DOI
Neelam Malap,

Thara V. Prabha

Atmospheric Research, Journal Year: 2023, Volume and Issue: 286, P. 106679 - 106679

Published: Feb. 26, 2023

Language: Английский

Citations

3
Breakups are complicated: an efficient representation of collisional breakup in the superdroplet method DOI Creative Commons
Emily de Jong, John Ben Mackay, Oleksii Bulenok

et al.

Geoscientific model development, Journal Year: 2023, Volume and Issue: 16(14), P. 4193 - 4211

Published: July 26, 2023

Abstract. A key constraint of particle-based methods for modeling cloud microphysics is the conservation total particle number, which required computational tractability. The process collisional breakup poses a particular challenge to this framework, as events often produce many droplet fragments varying sizes, would require creating new particles in system. This work introduces representation so-called “superdroplet” method conserves number superdroplets extends an existing stochastic collisional-coalescence scheme and samples from fragment size distribution additional Monte Carlo step. demonstrated set idealized box model single-column warm-rain simulations. We further discuss effects dynamic on distribution, hydrometeor population, microphysical rates. Box experiments serve characterize impacts properties such coalescence efficiency fragmentation function relative roles coalescence. results demonstrate that can stationary rates are approximately equal, it recovers expected behavior reduction precipitate-sized column model. algorithm presented here contributes open-source pythonic implementation superdroplet method, PySDM, will facilitate future research using microphysics.

Language: Английский

Citations

3
The Small‐Scale Mixing of Clouds With Their Environment: Impacts on Micro‐ and Macroscale Cloud Properties DOI
Fabian Hoffmann

Geophysical monograph, Journal Year: 2023, Volume and Issue: unknown, P. 255 - 270

Published: Dec. 15, 2023

Language: Английский

Citations

2
Quantifying the mixing of trade‐wind cumulus during the NEPHELAE‐EUREC4A field campaign with remotely piloted aircraft DOI
Nicolas Maury, Greg Roberts, Fleur Couvreux

et al.

Quarterly Journal of the Royal Meteorological Society, Journal Year: 2023, Volume and Issue: 149(752), P. 809 - 829

Published: Jan. 26, 2023

Abstract During the Network for studying Entrainment and microPHysics of cLouds using Adaptive Exploration (NEPHELAE)–ElUcidating RolE Cloud–Circulation Coupling in ClimAte (EUREC4A) field campaign January February 2020 Barbados, remotely piloted aircraft (RPA) were implemented to characterise structures trade‐wind cumulus a total 40 flights. Two observation methods tested: one making racetracks get statistics on clouds new sampling strategy sensor‐driven adaptive track an individual cloud autonomously throughout its lifetime. It appears from that there are two types cohabiting population, with small‐diameter (transect lengths less than 500 m) being buoyant larger greater m). Also, this statistical study shows do not have adiabatic core. These results compared tracked by sampling, which also show core is diluted environment. A comparison high‐resolution large‐eddy simulations these numerical studies tend underestimate mixing whole cloud.

Language: Английский

Citations

2