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

The Small-Scale Mixing of Clouds with their Environment: Impacts on Micro-and Macroscale Cloud Properties DOI Open Access
Fabian Hoffmann

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

Published: Feb. 14, 2023

The small-scale mixing of clouds with their environment is an essential cloud process. Following entrainment event, turbulent breaks down the entrained air and homogenizes it cloud, covering multiple orders magnitude in lengthscales from entraining eddies (∼ 100 m) to Kolmogorov length 1 mm). character this process, traditionally categorized into homogeneous inhomogeneous scenarios, can affect microphysical composition clouds, commensurate impacts on large-scale properties such as albedo lifetime. Based current physical understanding cloudy cloud-free air, chapter will summarize basic theories describing By considering wide range involved scales, we outline different observational numerical approaches used investigate process well methods parameterize models. Finally, review focusing microscale changes droplet size distribution macroscale effects relevant our climate system.

Language: Английский

Citations

2
Impact of aerosol processing in the transition of a stratocumulus cloud system to open cells: A comparison of Lagrangian and bin microphysics schemes in LES DOI Open Access
Kamal Kant Chandrakar, Hugh Morrison

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

Published: March 5, 2024

Stratocumulus clouds, a key component of global climate, are sensitive to aerosol properties. Aerosol-cloud-precipitation interactions in these clouds influence their closed-to-open cell dynamical transition and hence cloud cover radiative forcing. This study uses large-eddy simulations with Lagrangian super-particle bin microphysics schemes investigate impacts scavenging physical processing by on drizzle initiation the cellular process. The simulation using explicit representation cloud-borne shows significant that precipitation generation consequently transition. Sensitivity scheme comparison suggest reduced concentration due is primary microphysical catalyst for enhanced scheme. However, changes distribution shape through also contribute appreciably differences rate. Thus, both drive earlier rain formation open cells microphysics. highlights shortcoming Eulerian producing smaller mean drop radius water mixing ratios owing numerical diffusion. Initially larger induce faster development compared A positive feedback turn accelerates removal further production and, consequently, droplet number, increased size, spectral width.

Language: Английский

Citations

0
Adiabatic Evolution of Cloud Droplet Spectral Width: A New Look at an Old Problem DOI Creative Commons
Wojciech W. Grabowski, Hanna Pawłowska

Geophysical Research Letters, Journal Year: 2023, Volume and Issue: 50(3)

Published: Jan. 9, 2023

Abstract Spectral width of the cloud droplet spectrum is important for radiative properties and drizzle/rain development in warm ice‐free clouds. We use an adiabatic rising parcel model to study activation diffusional growth droplets, focusing on spectral evolution, contrasting clean polluted environments. A comprehensive equation used that includes kinetic, solute, surface tension effects. show those effects have appreciable impact evolution above base. Without effects, area standard deviation should not change once completed. In contrast, simulation results does increase with height, especially weak updrafts Implications modeling, applying conventional bin microphysics, are discussed.

Language: Английский

Citations

1
Paths From Aerosol Particles to Activation and Cloud Droplets in Shallow Cumulus Clouds: The Roles of Entrainment and Supersaturation Fluctuations DOI
Donggun Oh, Yign Noh, Fabian Hoffmann

et al.

Journal of Geophysical Research Atmospheres, Journal Year: 2023, Volume and Issue: 128(16)

Published: Aug. 7, 2023

Abstract The activation of aerosol particles and its contribution to cloud droplet size distributions in shallow cumulus clouds are investigated by analyzing the field simulation results using a Lagrangian model coupled with large eddy simulation, which allows explicit simulations tracking each super‐droplet. Analysis is focused on differences activations for following central updraft from base (CB) entrained above (EA). Time series various variables individual confirm distinctive nature CB EA activation. Strong supersaturation fluctuations induced entrainment turbulent mixing at edges cause most be deactivated soon after activation, substantially limiting their lifetime growth relative particles. Most net activation—the difference between deactivation—occurs vanishes aloft. Cloud spectra follow theoretical prediction high conditions, although proportional constant smaller because particle deactivation. deviate low conditions since they affected transport activated elsewhere.

Language: Английский

Citations

1
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

Citations

1