Simulation of the initial phase of Holuhraun eruption using the ICON-ART model to investigate aerosol- cloud interaction 

2021 ◽  
Author(s):  
Fatemeh Zarei ◽  
Corinna Hoose ◽  
Heike Vogel
Keyword(s):  
Hydrological Cycle ◽  
Number Concentration ◽  
Cloud Formation ◽  
Volcanic Plume ◽  
Source Strength ◽  
Cloud Droplets ◽  
Aerosol Cloud ◽  
Low Emission ◽  
High Emission ◽  
Aerosol Number Concentration

<p>Clouds play a key role in the atmosphere by completing the hydrological cycle and transferring water from the atmosphere to the earth's surface on the one hand, and affecting terrestrial radiation and solar radiation on the other hand. Although cloud properties are primarily affected by atmospheric dynamics, cloud microphysical features, which themselves are influenced by the number and chemical composition of aerosols that act as cloud condensation nuclei (CCN) and ice nuclei (IN) within cloud droplets, also affect cloud formation.</p><p> </p><p>The extent and quality of aerosols impact on cloud formation is one of the important open question of climate science. Volcanoes, which are a rich source of various chemical compounds, can help to improve the understanding of the effects of aerosols on clouds by providing a natural laboratory with locally high aerosol conditions adjacent to an unperturbed environment.</p><p> </p><p>In the present study, the impacts of changing the aerosol number concentration on clouds are investigated using the ICON-ART model. For this purpose, the Holuhraun volcano, which erupted on the island of Iceland in 2014, was simulated. It emitted small amounts of volcanic ash, and large emissions of gases primarily sulfur dioxide (SO2), which formed sulfate particles serving as CCN. Three simulations representing low, control, and high emission conditions were conducted. For the control simulation, the source strength of SO2 was based on the estimate by Malavelle et al. (2017). This rate, then, was reduced to one-fifth for the low emission experiment and increased by a factor of 5 for the high emission experiment.</p><p>First results indicate that increasing the source strength of SO2 is associated with an enhancement of sulfate aerosol number concentration and thus an increase of the number of cloud droplets, but with strongly nonlinear effects. For clouds within the volcanic plume, droplet concentrations are already high in the low emission scenario and do not increase significantly with higher emission strengths, partly due to model limitations. In addition, the effect of aerosols on the formation of cloud droplets is strongly dependent on environmental factors such as updraft velocity and supersaturation.</p><p>Keywords: Aerosol, Cloud, ICON-ART Model, Holuhraun eruption</p>

The Effect of using a New Parameterization of Nucleation in the WRF-Chem model on the Cluster Formation Rate and Particle Number Concentration in a Passive Volcanic Plume

2021 ◽  
Author(s):  
Somayeh Arghavani ◽  
Clémence Rose ◽  
Sandra Banson ◽  
Céline Planche ◽  
Karine Sellegri
Keyword(s):  
Particle Number ◽  
Cluster Formation ◽  
Formation Rate ◽  
Number Concentration ◽  
Cloud Formation ◽  
Scale Model ◽  
Volcanic Plume ◽  
Particle Number Concentration ◽  
Microphysics Scheme ◽  
Volcanic Emission

<p>Volcanic eruption is one of the main natural sources of atmospheric particles. In particular, evidence of New Particle Formation (NPF) from volcanic emission is reported in previous studies (Boulon et al., 2011; Sahyoun et al., 2019), which also suggests an essential role of sulfuric acid in this process. In addition, Rose et al. (2019) highlighted a significant contribution of the particles formed in the volcanic plume of the piton de la Fournaise to the budget of potential CCN at the Maïdo observatory, located ~40 km from the vent of the volcano. Therefore, it is predicted that the number and size of the cloud droplets, cloud growing and precipitation processes might be affected by the frequency of occurrence and characteristics of volcanically induced NPF in both local and regional scales, because volcanic plumes can extend far from the vent and even lower heights under the influence of the wind field and atmospheric dispersion. </p><p>Following the study of Planche et al. (2020), the effect of using the New Parameterization of Nucleation (NPN) derived from the measurements performed in the passive volcanic emission plume of Etna (37.748˚ N, 14.99˚ E; Italy) (Sahyoun et al., 2019) in the WRF-Chem model (Weather Research and Forecasting Model coupled with Chemistry) is assessed, with a specific focus on the cluster formation rate and particle number concentration including CCN. In particular, results obtained with the NPN are compared to the predictions obtained with the default model settings, and further with observations.</p><p>In the next step, the resulting aerosol fields will be used to further evaluate the influence of the newly formed and grown particles on cloud formation and properties in a 3D cloud-scale model using a detailed microphysics scheme (DESCAM; Flossmann and Wobrock, 2010; Planche et al. 2010; 2014) . </p>

scholarly journals Microphysical processing of aerosol particles in orographic clouds

2015 ◽  
Vol 15 (16) ◽  
pp. 9217-9236 ◽  
Author(s):  
S. Pousse-Nottelmann ◽  
E. M. Zubler ◽  
U. Lohmann
Keyword(s):  
Cloud Droplet ◽  
Number Concentration ◽  
Mixed Phase ◽  
Cloud Formation ◽  
Small Scale ◽  
Cloud Droplets ◽  
Aerosol Mass ◽  
Aerosol Processing ◽  
Orographic Clouds ◽  
Aerosol Scavenging

Abstract. An explicit and detailed treatment of cloud-borne particles allowing for the consideration of aerosol cycling in clouds has been implemented into COSMO-Model, the regional weather forecast and climate model of the Consortium for Small-scale Modeling (COSMO). The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed us to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener–Bergeron–Findeisen (WBF) process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snowflakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snowflakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. Thereby, the processes impact the total aerosol number and mass and additionally alter the shape of the aerosol size distributions by enhancing the internally mixed/soluble Aitken and accumulation mode and generating coarse-mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases the cloud droplet number concentration with possible implications for the ice crystal number concentration.

scholarly journals Aerosol nucleation spikes in the planetary boundary layer

2010 ◽  
Vol 10 (11) ◽  
pp. 26931-26959
Author(s):  
J.-P. Chen ◽  
T.-S. Tsai ◽  
S.-C. Liu
Keyword(s):  
Boundary Layer ◽  
Particle Production ◽  
Number Concentration ◽  
Cloud Formation ◽  
Actinic Flux ◽  
Aerosol Model ◽  
Large Fluctuations ◽  
Aerosol Number Concentration ◽  
Plausible Mechanism ◽  
Turbulence Condition

Abstract. Photochemically driven nucleation bursts, which typically occur in a few hours after sunrise, often produce strong aerosol number concentration (ANC) fluctuations. The causes of such ANC spikes were investigated using a detailed aerosol model running in the parcel mode. Two potential mechanisms for the ANC spikes are proposed and simulated. The blocking of actinic flux by scattered clouds can significantly influence new particle production, but this does not cause strong fluctuations in the number of aerosols within sizes greater than the detection limit of our measurements. A more plausible mechanism is the turbulence eddy effect. Strong aerosol nucleation may occur in both updrafts and downdrafts, while the cloud formation at the boundary layer top strongly reduces the number of aerosols. As the number of aerosols is sensitive to turbulence eddy and cloud formation properties, a changing turbulence condition would result in large fluctuations in the evolution of ANC similar to that observed at the surface.

scholarly journals Aerosol nucleation spikes in the planetary boundary layer

2011 ◽  
Vol 11 (14) ◽  
pp. 7171-7184 ◽  
Author(s):  
J.-P. Chen ◽  
T.-S. Tsai ◽  
S.-C. Liu
Keyword(s):  
Boundary Layer ◽  
Particle Production ◽  
Number Concentration ◽  
Cloud Formation ◽  
Actinic Flux ◽  
Aerosol Model ◽  
Large Fluctuations ◽  
Aerosol Number Concentration ◽  
Plausible Mechanism ◽  
Turbulence Condition

Abstract. Photochemically driven nucleation bursts, which typically occur within a few hours after sunrise, often produce strong aerosol number concentration (ANC) fluctuations. The causes of such ANC spikes were investigated using a detailed aerosol model running in the parcel mode. Two potential mechanisms for the ANC spikes were proposed and simulated. The blocking of actinic flux by scattered clouds can significantly influence new particle production, but this does not cause strong fluctuations in the number of aerosols within sizes greater than the detection limit of our measurements. A more plausible mechanism is the turbulence eddy effect. Strong aerosol nucleation may occur in both updrafts and downdrafts, while the cloud formation at the boundary layer top strongly reduces the number of aerosols. As the number of aerosols is sensitive to turbulence eddy and cloud formation properties, a changing turbulence condition would result in large fluctuations in the evolution of ANC similar to that observed at the surface.

scholarly journals A possible role of ground-based microorganisms on cloud formation in the atmosphere

2009 ◽  
Vol 6 (5) ◽  
pp. 10035-10056 ◽  
Author(s):  
S. Ekström ◽  
B. Nozière ◽  
M. Hultberg ◽  
T. Alsberg ◽  
J. Magnér ◽  
...  
Keyword(s):  
Surface Tension ◽  
Atmospheric Aerosols ◽  
Hydrological Cycle ◽  
Molecular Structures ◽  
Cloud Formation ◽  
Cloud Droplets ◽  
Organic Fractions ◽  
Earth’S System ◽  
Better Than

Abstract. The formation of clouds is an important process for the atmosphere, the hydrological cycle, and climate, but also a difficult one to predict because some aspects of the transformations of aerosol particles into cloud droplets are still not well understood. In this work, we show that microorganisms might affect cloud formation without leaving the Earth's surface by releasing biological surfactants (or biosurfactants) in the environment, that make their way into atmospheric aerosols and should significantly enhance their conversion into of cloud droplets. In the first part of this work, the cloud-nucleating efficiency (or "CCN" efficiency) of standard biosurfactants was characterized by osmolality and surface tension measurements and found to be better than for any aerosol material studied so far, including inorganic salts. These results identify molecular structures that give to organic compounds exceptional CCN properties. In the second part, atmospheric aerosols sampled at different locations (temperate & tropical, forested & marine ones) were found to all have a surface tension below 30 mN/m, which can only be accounted for by the presence of biosurfactants. The results also showed that these biosurfactants were concentrated enough to significantly affect the surface tension of these aerosols and enhance their CCN efficiency. The presence of such strong biosurfactants in aerosols would be consistent with the recent identification of organic fractions of higher CCN efficiency than ammonium sulfate in aerosols. And a role of microorganisms at the Earth's surface on clouds could also explain previously reported correlations between algae bloom and cloud cover. Our results also suggest that biosurfactants might be common in aerosols and thus of global relevance. If their impact on cloud formation is confirmed by future studies, this work would have identified a new role of microorganisms at the Earth's surface on the atmosphere, and a new component of the Earth's system and climate.

scholarly journals Earth System Model Aerosol-Cloud Diagnostics Package (ESMAC Diags) Version 1: Assessing E3SM Aerosol Predictions Using Aircraft, Ship, and Surface Measurements

2021 ◽  
Author(s):  
Shuaiqi Tang ◽  
Jerome D. Fast ◽  
Kai Zhang ◽  
Joseph C. Hardin ◽  
Adam C. Varble ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Size Distribution ◽  
Number Concentration ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Aerosol Cloud ◽  
Surface Measurements ◽  
Aerosol Number Concentration ◽  
Aerosol Properties

Abstract. An Earth System Model (ESM) aerosol-cloud diagnostics package is developed to facilitate the routine evaluation of aerosols, clouds and aerosol-cloud interactions simulated by the Department of Energy’s (DOE) Energy Exascale Earth System Model (E3SM). The first version focuses on comparing simulated aerosol properties with aircraft, ship, and surface measurements, most of them are measured in-situ. The diagnostics currently covers six field campaigns in four geographical regions: Eastern North Atlantic (ENA), Central U.S. (CUS), Northeastern Pacific (NEP) and Southern Ocean (SO). These regions produce frequent liquid or mixed-phase clouds with extensive measurements available from the Atmospheric Radiation Measurement (ARM) program and other agencies. Various types of diagnostics and metrics are performed for aerosol number, size distribution, chemical composition, CCN concentration and various meteorological quantities to assess how well E3SM represents observed aerosol properties across spatial scales. Overall, E3SM qualitatively reproduces the observed aerosol number concentration, size distribution and chemical composition reasonably well, but underestimates Aitken mode and overestimates accumulation mode aerosols over the CUS region, and underestimates aerosol number concentration over the SO region. The current version of E3SM struggles to reproduce new particle formation events frequently observed over both the CUS and ENA regions, indicating missing processes in current parameterizations. The diagnostics package is coded and organized in a way that can be easily extended to other field campaign datasets and adapted to higher-resolution model simulations. Future releases will include comprehensive cloud and aerosol-cloud interaction diagnostics.

scholarly journals A possible role of ground-based microorganisms on cloud formation in the atmosphere

2010 ◽  
Vol 7 (1) ◽  
pp. 387-394 ◽  
Author(s):  
S. Ekström ◽  
B. Nozière ◽  
M. Hultberg ◽  
T. Alsberg ◽  
J. Magnér ◽  
...  
Keyword(s):  
Surface Tension ◽  
Atmospheric Aerosols ◽  
Hydrological Cycle ◽  
Molecular Structures ◽  
Cloud Formation ◽  
Cloud Droplets ◽  
Natural Substances ◽  
Marine Site ◽  
Better Than

Abstract. The formation of clouds is an important process for the atmosphere, the hydrological cycle, and climate, but some aspects of it are not completely understood. In this work, we show that microorganisms might affect cloud formation without leaving the Earth's surface by releasing biological surfactants (or biosurfactants) in the environment, that make their way into atmospheric aerosols and could significantly enhance their activation into cloud droplets. In the first part of this work, the cloud-nucleating efficiency of standard biosurfactants was characterized and found to be better than that of any aerosol material studied so far, including inorganic salts. These results identify molecular structures that give organic compounds exceptional cloud-nucleating properties. In the second part, atmospheric aerosols were sampled at different locations: a temperate coastal site, a marine site, a temperate forest, and a tropical forest. Their surface tension was measured and found to be below 30 mN/m, the lowest reported for aerosols, to our knowledge. This very low surface tension was attributed to the presence of biosurfactants, the only natural substances able to reach to such low values. The presence of strong microbial surfactants in aerosols would be consistent with the organic fractions of exceptional cloud-nucleating efficiency recently found in aerosols, and with the correlations between algae bloom and cloud cover reported in the Southern Ocean. The results of this work also suggest that biosurfactants might be common in aerosols and thus of global relevance. If this is confirmed, a new role for microorganisms on the atmosphere and climate could be identified.

scholarly journals Influence of aerosols on the formation and development of radiation fog

2009 ◽  
Vol 9 (5) ◽  
pp. 17963-18019 ◽  
Author(s):  
J. Rangognio ◽  
P. Tulet ◽  
T. Bergot ◽  
L. Gomes ◽  
O. Thouron ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Chemical Properties ◽  
Cloud Droplet ◽  
Critical Value ◽  
Number Concentration ◽  
Cloud Droplets ◽  
Radiation Fog ◽  
Cloud Water Content ◽  
Aerosol Number Concentration ◽  
The Impact

Abstract. This paper assesses the impact of aerosol properties on the formation and the development of radiation fog. Simulations were performed using the Meso-NH meteorological model including the ORILAM aerosol scheme coupled with a two-moment microphysical cloud scheme (number concentration of cloud droplets and cloud water content). The activation scheme used was taken from the work of Abdul-Razzak and Ghan (2004). "Off-line" sensitivity analysis of CCN (Cloud Condensation Nuclei) activation was performed on number, median diameter and chemical compounds of aerosols. During this "off-line" study, the interactions with the other physical processes (e.g. radiative) were not taken into account since the cooling rate was imposed. Different regimes of CCN activation and a critical value of aerosol number concentration were found. This critical aerosol number corresponds to the maximum of activated cloud droplets for a given cooling rate and given aerosol chemical properties. As long as the aerosol number concentration is below this critical value, the cloud droplet number increases when the aerosol number increases. But when the aerosol number concentration exceeds this critical value, the cloud droplet number decreases when aerosol number increases. A sensitivity study on aerosol chemical composition showed that the CCN activation was limited in the case of hydrophilic aerosol composed of material with a solubility in the 10% range. An event observed during the ParisFOG field experiment was simulated. This case took place in the polluted sub-urban area of Paris (France) characterized by particle concentrations of 17 000 aerosols per cm3. 1D simulations successfully reproduced the observed temporal evolution of the fog layer. Beyond the initial fog formation at the surface, cloud droplet formation occurred at the top of the fog layer where the cooling rate was maximum, reaching more than −10 K h−1. These simulations confirm that the aerosol particle number concentration is a key parameter for the accurate prediction of the microphysical properties of a fog layer and also influences the vertical development of fog. The important of the interaction between microphysical and radiative processes is illustrated, showing how the life cycle of a fog layer is determined by the CCN number concentration and chemical properties.

scholarly journals Heterogeneous nucleation of water vapor on different types of black carbon particles

2020 ◽  
Author(s):  
Ari Laaksonen ◽  
Jussi Malila ◽  
Athanasios Nenes
Keyword(s):  
Water Vapor ◽  
Black Carbon ◽  
Heterogeneous Nucleation ◽  
Hydrological Cycle ◽  
Quantitative Description ◽  
Nucleation Theory ◽  
Cloud Formation ◽  
Cloud Droplets ◽  
Carbon Particles ◽  
Different Types

Abstract. Heterogeneous nucleation of water vapor on insoluble particles affects cloud formation, precipitation, the hydrological cycle and climate. Despite its importance, heterogeneous nucleation remains a poorly understood phenomenon that relies heavily on empirical information for its quantitative description. Here, we examine heterogeneous nucleation of water vapor on and cloud drop activation of different types of soots, both pure black carbon particles, and black carbon particles mixed with secondary organic matter. We show that the recently developed adsorption nucleation theory quantitatively predicts the nucleation of water and droplet formation upon particles of the various soot types. A surprising consequence of this new understanding is that, with sufficient adsorption site density, soot particles can activate into cloud droplets – even when completely lacking any soluble material.

scholarly journals Microphysical processing of aerosol particles in orographic clouds

2015 ◽  
Vol 15 (2) ◽  
pp. 2405-2458
Author(s):  
S. Pousse-Nottelmann ◽  
E. M. Zubler ◽  
U. Lohmann
Keyword(s):  
Climate Model ◽  
Cloud Droplet ◽  
Number Concentration ◽  
Mixed Phase ◽  
Cloud Formation ◽  
Cloud Droplets ◽  
Aerosol Mass ◽  
Aerosol Processing ◽  
Orographic Clouds ◽  
Aerosol Scavenging

Abstract. An explicit and detailed treatment of cloud-borne particles allowing for the consideration of aerosol cycling in clouds has been implemented in the regional weather forecast and climate model COSMO. The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener-Bergeron-Findeisen process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snow flakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snow flakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. However, the processes not only impact the total aerosol number and mass, but also the shape of the aerosol size distributions by enhancing the internally mixed/soluble accumulation mode and generating coarse mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases the cloud droplet number concentration with possible implications for the ice crystal number concentration.

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