The role of boundary layer aerosol particles for the development of deep convective clouds: A high-resolution 3D model with detailed (bin) microphysics applied to CRYSTAL-FACE

2009 ◽  
Vol 91 (1) ◽  
pp. 62-78 ◽  
Author(s):  
Delphine Leroy ◽  
Wolfram Wobrock ◽  
Andrea I. Flossmann
Keyword(s):  
Boundary Layer ◽  
High Resolution ◽  
3D Model ◽  
Aerosol Particles ◽  
Crystal Face ◽  
Convective Clouds ◽  
Deep Convective Clouds ◽  
Bin Microphysics

scholarly journals Aerosol characteristics and particle production in the upper troposphere over the Amazon Basin

2018 ◽  
Vol 18 (2) ◽  
pp. 921-961 ◽  
Author(s):  
Meinrat O. Andreae ◽  
Armin Afchine ◽  
Rachel Albrecht ◽  
Bruna Amorim Holanda ◽  
Paulo Artaxo ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Amazon Basin ◽  
Deep Convection ◽  
Aerosol Particles ◽  
Condensation Nuclei ◽  
Upper Troposphere ◽  
Convective Clouds ◽  
Tropospheric Aerosol ◽  
Volatile Organic ◽  
Deep Convective Clouds

Abstract. Airborne observations over the Amazon Basin showed high aerosol particle concentrations in the upper troposphere (UT) between 8 and 15 km altitude, with number densities (normalized to standard temperature and pressure) often exceeding those in the planetary boundary layer (PBL) by 1 or 2 orders of magnitude. The measurements were made during the German–Brazilian cooperative aircraft campaign ACRIDICON–CHUVA, where ACRIDICON stands for Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems and CHUVA is the acronym for Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modeling and to the GPM (global precipitation measurement), on the German High Altitude and Long Range Research Aircraft (HALO). The campaign took place in September–October 2014, with the objective of studying tropical deep convective clouds over the Amazon rainforest and their interactions with atmospheric trace gases, aerosol particles, and atmospheric radiation. Aerosol enhancements were observed consistently on all flights during which the UT was probed, using several aerosol metrics, including condensation nuclei (CN) and cloud condensation nuclei (CCN) number concentrations and chemical species mass concentrations. The UT particles differed sharply in their chemical composition and size distribution from those in the PBL, ruling out convective transport of combustion-derived particles from the boundary layer (BL) as a source. The air in the immediate outflow of deep convective clouds was depleted of aerosol particles, whereas strongly enhanced number concentrations of small particles (< 90 nm diameter) were found in UT regions that had experienced outflow from deep convection in the preceding 5–72 h. We also found elevated concentrations of larger (> 90 nm) particles in the UT, which consisted mostly of organic matter and nitrate and were very effective CCN. Our findings suggest a conceptual model, where production of new aerosol particles takes place in the continental UT from biogenic volatile organic material brought up by deep convection and converted to condensable species in the UT. Subsequently, downward mixing and transport of upper tropospheric aerosol can be a source of particles to the PBL, where they increase in size by the condensation of biogenic volatile organic compound (BVOC) oxidation products. This may be an important source of aerosol particles for the Amazonian PBL, where aerosol nucleation and new particle formation have not been observed. We propose that this may have been the dominant process supplying secondary aerosol particles in the pristine atmosphere, making clouds the dominant control of both removal and production of atmospheric particles.

scholarly journals Theoretical basis for convective invigoration due to increased aerosol concentration

2011 ◽  
Vol 11 (11) ◽  
pp. 5407-5429 ◽  
Author(s):  
Z. J. Lebo ◽  
J. H. Seinfeld
Keyword(s):  
Number Concentration ◽  
Latent Heating ◽  
Heating Rates ◽  
Microphysics Scheme ◽  
Convective Clouds ◽  
Aerosol Loading ◽  
Significant Difference ◽  
Deep Convective Clouds ◽  
Bin Microphysics ◽  
Cumulative Precipitation

Abstract. The potential effects of increased aerosol loading on the development of deep convective clouds and resulting precipitation amounts are studied by employing the Weather Research and Forecasting (WRF) model as a detailed high-resolution cloud resolving model (CRM) with both detailed bulk and bin microphysics schemes. Both models include a physically-based activation scheme that incorporates a size-resolved aerosol population. We demonstrate that the aerosol-induced effect is controlled by the balance between latent heating and the increase in condensed water aloft, each having opposing effects on buoyancy. It is also shown that under polluted conditions, increases in the CCN number concentration reduce the cumulative precipitation due to the competition between the sedimentation and evaporation/sublimation timescales. The effect of an increase in the IN number concentration on the dynamics of deep convective clouds is small and the resulting decrease in domain-averaged cumulative precipitation is shown not to be statistically significant, but may act to suppress precipitation. It is also shown that even in the presence of a decrease in the domain-averaged cumulative precipitation, an increase in the precipitation variance, or in other words, andincrease in rainfall intensity, may be expected in more polluted environments, especially in moist environments. A significant difference exists between the predictions based on the bin and bulk microphysics schemes of precipitation and the influence of aerosol perturbations on updraft velocity within the convective core. The bulk microphysics scheme shows little change in the latent heating rates due to an increase in the CCN number concentration, while the bin microphysics scheme demonstrates significant increases in the latent heating aloft with increasing CCN number concentration. This suggests that even a detailed two-bulk microphysics scheme, coupled to a detailed activation scheme, may not be sufficient to predict small changes that result from perturbations in aerosol loading.

scholarly journals The role of urban boundary layer investigated by high resolution models and ground based observations in Rome area: a step for understanding parameterizations potentialities

2013 ◽  
Vol 6 (3) ◽  
pp. 5297-5344
Author(s):  
E. Pichelli ◽  
R. Ferretti ◽  
M. Cacciani ◽  
A. M. Siani ◽  
V. Ciardini ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Resolution ◽  
Urban Areas ◽  
Prediction Models ◽  
Weather Prediction ◽  
Sonic Anemometer ◽  
Lower Atmosphere ◽  
Area Of Interest ◽  
The Impact

Abstract. The urban forcing on thermo-dynamical conditions can largely influences local evolution of the atmospheric boundary layer. Urban heat storage can produce noteworthy mesoscale perturbations of the lower atmosphere. The new generations of high-resolution numerical weather prediction models (NWP) is nowadays largely applied also to urban areas. It is therefore critical to reproduce correctly the urban forcing which turns in variations of wind, temperature and water vapor content of the planetary boundary layer (PBL). WRF-ARW, a new model generation, has been used to reproduce the circulation in the urban area of Rome. A sensitivity study is performed using different PBL and surface schemes. The significant role of the surface forcing in the PBL evolution has been verified by comparing model results with observations coming from many instruments (LiDAR, SODAR, sonic anemometer and surface stations). The crucial role of a correct urban representation has been demonstrated by testing the impact of different urban canopy models (UCM) on the forecast. Only one of three meteorological events studied will be presented, chosen as statistically relevant for the area of interest. The WRF-ARW model shows a tendency to overestimate vertical transmission of horizontal momentum from upper levels to low atmosphere, that is partially corrected by local PBL scheme coupled with an advanced UCM. Depending on background meteorological scenario, WRF-ARW shows an opposite behavior in correctly representing canopy layer and upper levels when local and non local PBL are compared. Moreover a tendency of the model in largely underestimating vertical motions has been verified.

New MESSy scavenging subroutine to treat aerosol particles gas-phase partitioning in convective clouds

2021 ◽  
Author(s):  
Giorgio Taverna ◽  
Marc Barra ◽  
Holger Tost
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Aerosol Particles ◽  
Phase Partitioning ◽  
Convective Clouds ◽  
Terrestrial Atmosphere ◽  
Deep Convective Clouds ◽  
High Level

&lt;p&gt;The Modular Earth Submodel System (MESSy) has been proven to be successful in the understanding of several processes which characterize the terrestrial atmosphere and climate.&lt;/p&gt;&lt;p&gt;However, the complexity of aerosol particles/gas phase partitioning of species in deep convective clouds together with the inherent problems of modelling sub-grid scale processes, make MESSy results significant underestimated, especially in case of SO&lt;sub&gt;2&lt;/sub&gt;, when compared with available flight observations. For this reason, the subroutine which reproduce the scavenging of these species has been updated to include a more realistic treatment of liquid/phase partitioning of aerosol induced species in high level clouds.&lt;/p&gt;&lt;p&gt;Results obtained are shown in this poster.&lt;/p&gt;

Deep convective clouds as aerosol production engines: Role of insoluble organics

2006 ◽  
Vol 111 (D17) ◽  
Author(s):  
Markku Kulmala ◽  
Anni Reissell ◽  
Mikko Sipilä ◽  
Boris Bonn ◽  
Taina M. Ruuskanen ◽  
...  
Keyword(s):  
Convective Clouds ◽  
Deep Convective Clouds

scholarly journals Revisiting adiabatic fraction estimations in cumulus clouds: high-resolution simulations with a passive tracer

2021 ◽  
Vol 21 (21) ◽  
pp. 16203-16217
Author(s):  
Eshkol Eytan ◽  
Ilan Koren ◽  
Orit Altaratz ◽  
Mark Pinsky ◽  
Alexander Khain
Keyword(s):  
High Resolution ◽  
Accurate Description ◽  
Cloud Base ◽  
Passive Tracer ◽  
Cumulus Clouds ◽  
Microphysics Scheme ◽  
Convective Clouds ◽  
Open Questions ◽  
Bin Microphysics ◽  
Normalized Concentration

Abstract. The process of mixing in warm convective clouds and its effects on microphysics are crucial for an accurate description of cloud fields, weather, and climate. Still, they remain open questions in the field of cloud physics. Adiabatic regions in the cloud could be considered non-mixed areas and therefore serve as an important reference to mixing. For this reason, the adiabatic fraction (AF) is an important parameter that estimates the mixing level in the cloud in a simple way. Here, we test different methods of AF calculations using high-resolution (10 m) simulations of isolated warm cumulus clouds. The calculated AFs are compared with a normalized concentration of a passive tracer, which is a measure of dilution by mixing. This comparison enables the examination of how well the AF parameter can determine mixing effects and the estimation of the accuracy of different approaches used to calculate it. Comparison of three different methods to derive AF, with the passive tracer, shows that one method is much more robust than the others. Moreover, this method's equation structure also allows for the isolation of different assumptions that are often practiced when calculating AF such as vertical profiles, cloud-base height, and the linearity of AF with height. The use of a detailed spectral bin microphysics scheme allows an accurate description of the supersaturation field and demonstrates that the accuracy of the saturation adjustment assumption depends on aerosol concentration, leading to an underestimation of AF in pristine environments.

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