scholarly journals Implementing Gas-to-Particle Partitioning of Semi-Volatile Inorganic Compounds in UCLALES-SALSA

2020 ◽  
Author(s):  
Innocent Kudzotsa ◽  
Harri Kokkola ◽  
Juha Tonttila ◽  
Tomi Raatikainen ◽  
Sami Romakkaniemi
Keyword(s):  
Inorganic Compounds ◽  
Cloud Condensation Nuclei ◽  
Three Dimensional ◽  
Cloud Droplet ◽  
Dominant Factor ◽  
Cloud Droplets ◽  
Cloud Properties ◽  
Cloud Scavenging ◽  
Scavenging Efficiency ◽  
Ccn Activity

Abstract. We investigated the effect of inorganic semi-volatile compounds (SVC) HNO3 and NH3 on the cloud condensation nuclei (CCN) activity of aerosols and the subsequent changes in cloud properties. This was done by upgrading our state-of-the-art large eddy simulator – UCLALES-SALSA, which was modified to include the treatment of the condensation and dissolution of SVCs onto pre-existing aerosols and cloud droplets. The immediate effect of these SVCs on aerosols was to shift the aerosol dry size distribution towards larger sizes as a result of their co-condensation with water vapour. Since the dry size of a CCN is the dominant factor determining its CCN activity, a marked increase in cloud droplet number concentration(similar to the Twomey effect) was noted both in zero- and three-dimensional simulations when gas-phase concentrations of VCs were increased. As the overall amount of precipitation was small in the simulated stratocumulus case, the increase in droplet concentration led to a smaller mean size and reduced drizzle. Within clouds, the smaller droplets contain a relatively higher amount of nitrate than the larger ones, and as the drizzle is mainly formed through large droplets, the ammonium nitrate in-cloud scavenging is weaker than would be estimated based on average droplet composition. The model was also able to simulate the relatively more acidic interstitial particles than cloud droplets. However, below the cloud, condensation of gases on drizzling droplets quickly increases their overall wet scavenging efficiency compared to sulphate.

scholarly journals The single-particle mixing state and cloud scavenging of black carbon: a case study at a high-altitude mountain site in southern China

2017 ◽  
Vol 17 (24) ◽  
pp. 14975-14985 ◽  
Author(s):  
Guohua Zhang ◽  
Qinhao Lin ◽  
Long Peng ◽  
Xinhui Bi ◽  
Duohong Chen ◽  
...  
Keyword(s):  
Black Carbon ◽  
Single Particle ◽  
Southern China ◽  
Cloud Droplet ◽  
Mixing State ◽  
Cloud Droplets ◽  
Aerosol Mass ◽  
Mountain Site ◽  
Cloud Scavenging ◽  
Scavenging Efficiency

Abstract. In the present study, a ground-based counterflow virtual impactor (GCVI) was used to sample cloud droplet residual (cloud RES) particles, while a parallel PM2.5 inlet was used to sample cloud-free or cloud interstitial (cloud INT) particles. The mixing state of black carbon (BC)-containing particles and the mass concentrations of BC in the cloud-free, RES and INT particles were investigated using a single-particle aerosol mass spectrometer (SPAMS) and two aethalometers, respectively, at a mountain site (1690 m a. s. l. ) in southern China. The measured BC-containing particles were extensively internally mixed with sulfate and were scavenged into cloud droplets (with number fractions of 0.05–0.45) to a similar (or slightly lower) extent as all the measured particles (0.07–0.6) over the measured size range of 0.1–1.6 µm. The results indicate the preferential activation of larger particles and/or that the production of secondary compositions shifts the BC-containing particles towards larger sizes. BC-containing particles with an abundance of both sulfate and organics were scavenged less than those with sulfate but limited organics, implying the importance of the mixing state on the incorporation of BC-containing particles into cloud droplets. The mass scavenging efficiency of BC with an average of 33 % was similar for different cloud events independent of the air mass. This is the first time that both the mixing state and cloud scavenging of BC in China have been reported. Our results would improve the knowledge on the concentration, mixing state, and cloud scavenging of BC in the free troposphere.

scholarly journals The single-particle mixing state and cloud scavenging of black carbon at a high-altitude mountain site in southern China

2017 ◽  
Author(s):  
Guohua Zhang ◽  
Qinhao Lin ◽  
Long Peng ◽  
Xinhui Bi ◽  
Duohong Chen ◽  
...  
Keyword(s):  
Black Carbon ◽  
Single Particle ◽  
Southern China ◽  
Climate Impacts ◽  
Limited Information ◽  
Mixing State ◽  
Cloud Droplets ◽  
Mountain Site ◽  
Cloud Scavenging ◽  
Scavenging Efficiency

Abstract. In the present study, a ground-based counterflow virtual impactor (GCVI) was used to sample cloud droplet residual (cloud RES) particles, while a parallel PM2.5 inlet was used to sample cloud-free or cloud interstitial (cloud INT) particles. The mixing state of black carbon (BC)-containing particles in a size range of 0.1–1.6 µm and the mass concentrations of BC in the cloud-free, RES and INT particles were investigated using a single particle aerosol mass spectrometer (SPAMS) and two aethalometers, respectively, at a mountain site (1690 m a.s.l.) in southern China. The measured BC-containing particles were internally mixed extensively with sulfate, and were activated into cloud droplets to the same extent as all the measured particles. The results indicate the preferential activation of larger particles and/or that the production of secondary compositions shifts the BC-containing particles towards larger sizes. BC-containing particles with an abundance of both sulfate and organics were activated less than those with sulfate but limited organics, implying the importance of the mixing state on the incorporation of BC-containing particles into cloud droplets. The mass scavenging efficiency of BC with an average of 33 % was similar for different cloud events independent of the air mass. This is the first time that both the mixing state and cloud scavenging of BC in China have been reported. Since limited information on BC-containing particles in the free troposphere is available, the results also provide an important reference for the representation of BC concentrations, properties, and climate impacts in modeling studies.

scholarly journals Thermodynamic properties and cloud droplet activation of a series of oxo-acids

2010 ◽  
Vol 10 (13) ◽  
pp. 5873-5890 ◽  
Author(s):  
M. Frosch ◽  
A. A. Zardini ◽  
S. M. Platt ◽  
L. Müller ◽  
M.-C. Reinnig ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Thermodynamic Properties ◽  
Vapor Pressure ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Dicarboxylic Acids ◽  
Atmospheric Particulate Matter ◽  
Flow Tube ◽  
Order Of Magnitude ◽  
Ccn Activity

Abstract. We have investigated the thermodynamic properties of four aliphatic oxo-dicarboyxlic acids identified or thought to be present in atmospheric particulate matter: oxosuccinic acid, 2-oxoglutaric acid, 3-oxoglutaric acid, and 4-oxopimelic acid. The compounds were characterized in terms of their cloud condensation nuclei (CCN) activity, vapor pressure, density, and tendency to decarboxylate in aqueous solution. We deployed a variety of experimental techniques and instruments: a CCN counter, a Tandem Differential Mobililty Analyzer (TDMA) coupled with a laminar flow-tube, and liquid chromatography/mass spectrometry (LC/MS). The presence of the oxo functional group in the α-position causes the vapor pressure of the compounds to diminish by an order of magnitude with respect to the parent dicarboxylic acid, while the CCN activity is similar or increased. Dicarboxylic acids with an oxo-group in the β-position decarboxylate in aqueous solution. We studied the effects of this process on our measurements and findings.

scholarly journals Sensitivity to deliberate sea salt seeding of marine clouds – observations and model simulations

2011 ◽  
Vol 11 (10) ◽  
pp. 29527-29559 ◽  
Author(s):  
K. Alterskjær ◽  
J. E. Kristjánsson ◽  
Ø. Seland
Keyword(s):  
Cloud Droplet ◽  
Sea Salt ◽  
Maximum Effect ◽  
Cloud Droplets ◽  
Cloud Optical Depth ◽  
Susceptibility Function ◽  
Cloud Properties ◽  
The Pacific ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Modal Radius

Abstract. Sea salt seeding of marine clouds to increase their albedo is a proposed technique to counteract or slow global warming. In this study, we first investigate the susceptibility of marine clouds to sea salt injections, using observational data of cloud droplet number concentration, cloud optical depth, and liquid cloud fraction from the MODIS (Moderate Resolution Imaging Spectroradiometer) instruments on board the Aqua and Terra satellites. We then compare the derived susceptibility function to a corresponding estimate from the Norwegian Earth System Model (NorESM). Results compare well between simulations and observations, showing that stratocumulus regions off the west coast of the major continents along with large regions in the Pacific and the Indian Oceans are susceptible. We then carry out geo-engineering experiments with a uniform increase of 10−9 kg m−2 s−1 in emissions of sea salt particles with a modal radius of 0.13 μm. The increased sea salt concentrations and the resulting change in marine cloud properties lead to a globally averaged forcing of −4.8 W m−2 at the top of the atmosphere, more than cancelling a doubling of CO2 concentrations. The forcing is large in areas found to be sensitive by using the susceptibility function, confirming its usefulness as an indicator of where to inject sea salt for maximum effect. Results also show that the effectiveness of sea salt seeding is reduced because the injected sea salt provide a large surface area for water vapor and gaseous sulphuric acid to condense on, thereby lowering the maximum supersaturation and suppressing the formation and lifetime of sulphate particles. In some areas, our simulations show an overall reduction in the CCN concentration and the number of activated cloud droplets decreases, resulting in a positive globally averaged forcing.

scholarly journals LIMA (v1.0): a two-moment microphysical scheme driven by a multimodal population of cloud condensation and ice freezing nuclei

2015 ◽  
Vol 8 (9) ◽  
pp. 7767-7820 ◽  
Author(s):  
B. Vié ◽  
J.-P. Pinty ◽  
S. Berthet ◽  
M. Leriche
Keyword(s):  
Mesoscale Model ◽  
Cloud Condensation Nuclei ◽  
Three Dimensional ◽  
Single Equation ◽  
Ice Crystals ◽  
Growth Mode ◽  
Squall Line ◽  
Complex Nature ◽  
Cloud Droplets ◽  
Ice Clouds

Abstract. The paper describes the 2-moment microphysical scheme LIMA (Liquid Ice Multiple Aerosols), which relies on the prognostic evolution of a three-dimensional (3-D) aerosol population, and the careful description of the nucleating properties that enable cloud droplets and pristine ice crystals to form. LIMA uses the aerosol nucleating properties to form cloud droplets and pristine ice crystals. Several modes of Cloud Condensation Nuclei (CCN) and Ice Freezing Nuclei (IFN) are considered individually. A special class of partially soluble IFN is also introduced. These "aged" IFN act first as CCN and then as IFN by immersion nucleation at low temperatures. All the CCN modes are in competition with each other, as expressed by the single equation of maximum supersaturation. The IFN are insoluble aerosols that nucleate ice in several ways (condensation, deposition and immersion freezing) assuming the singular hypothesis. The scheme also includes the homogeneous freezing of cloud droplets, the Hallett–Mossop ice multiplication process and the freezing of haze at very low temperature. LIMA assumes that water vapour is in thermodynamic equilibrium with the population of cloud droplets (adjustment to saturation in warm clouds). In ice clouds, the prediction of the number concentration of the pristine ice crystals is used to compute explicit deposition and sublimation rates (leading to free under/supersaturation over ice). The formation of hydrometeors is standard. The autoconversion, accretion and self-collection processes shape the raindrop spectra. The initiation of the large crystals and aggregates category is the result of the depositional growth of large crystals beyond a critical size. Aggregation and riming are computed explicitly. Heavily rimed crystals (graupel) can experience a dry or wet growth mode. An advanced version of the scheme includes a separate hail category of particles forming and growing exclusively in the wet growth mode. The sedimentation of all particle types is included. The LIMA scheme is inserted in the cloud-resolving mesoscale model Meso-NH. The flexibility of LIMA is illustrated by two 2-D experiments. The first one highlights the sensitivity of orographic ice clouds to IFN types and IFN concentrations. Then a squall line case discusses the microstructure of a mixed-phase cloud and the impacts of pure CCN and IFN polluting plumes. The experiments show that LIMA captures the complex nature of aerosol-cloud interactions leading to different pathways for cloud and precipitation formation.

scholarly journals Impact of isolated atmospheric aging processes on the cloud condensation nuclei activation of soot particles

2019 ◽  
Vol 19 (24) ◽  
pp. 15545-15567 ◽  
Author(s):  
Franz Friebel ◽  
Prem Lobo ◽  
David Neubauer ◽  
Ulrike Lohmann ◽  
Saskia Drossaart van Dusseldorp ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Climate Model ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Cloud Droplet ◽  
High Sensitivity ◽  
Condensation Nuclei ◽  
Soot Particles ◽  
Atmospheric Aging ◽  
Ccn Activity

Abstract. The largest contributors to the uncertainty in assessing the anthropogenic contribution in radiative forcing are the direct and indirect effects of aerosol particles on the Earth's radiative budget. Soot particles are of special interest since their properties can change significantly due to aging processes once they are emitted into the atmosphere. Probably the largest obstacle for the investigation of these processes in the laboratory is the long atmospheric lifetime of 1 week, requiring tailored experiments that cover this time span. This work presents results on the ability of two types of soot, obtained using a miniCAST soot generator, to act as cloud condensation nuclei (CCN) after exposure to atmospherically relevant levels of ozone (O3) and humidity. Aging times of up to 12 h were achieved by successful application of the continuous-flow stirred tank reactor (CSTR) concept while allowing for size selection of particles prior to the aging step. Particles of 100 nm diameter and rich in organic carbon (OC) that were initially CCN inactive showed significant CCN activity at supersaturations (SS) down to 0.3 % after 10 h of exposure to 200 ppb of O3. While this process was not affected by different levels of relative humidity in the range of 5 %–75 %, a high sensitivity towards the ambient/reaction temperature was observed. Soot particles with a lower OC content required an approximately 4-fold longer aging duration to show CCN activity at the same SS. Prior to the slow change in the CCN activity, a rapid increase in the particle diameter was detected which occurred within several minutes. This study highlights the applicability of the CSTR approach for the simulation of atmospheric aging processes, as aging durations beyond 12 h can be achieved in comparably small aerosol chamber volumes (<3 m3). Implementation of our measurement results in a global aerosol-climate model, ECHAM6.3-HAM2.3, showed a statistically significant increase in the regional and global CCN burden and cloud droplet number concentration.

scholarly journals Retrieval of optical thickness and droplet effective radius of inhomogeneous clouds using deep learning

2017 ◽  
Author(s):  
Rintaro Okamura ◽  
Hironobu Iwabuchi ◽  
K. Sebastian Schmidt
Keyword(s):  
Deep Learning ◽  
Radiative Transfer ◽  
Optical Thickness ◽  
Three Dimensional ◽  
Cloud Droplet ◽  
Effective Radius ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Transfer Effects ◽  
Cloud Properties

Abstract. Three-dimensional (3D) radiative transfer effects are a major source of retrieval errors in satellite-based optical re- mote sensing of clouds. In this study, we present two retrieval methods based on deep learning. We use deep neural networks (DNNs) to retrieve multipixel estimates of cloud optical thickness and column-mean cloud droplet effective radius simultane- ously from multispectral, multipixel radiances. Cloud field data are obtained from large-eddy simulations, and a 3D radiative transfer model is employed to simulate upward radiances from clouds. The cloud and radiance data are used to train and test the DNNs. The proposed DNN-based retrieval is shown to be more accurate than the existing look-up table approach that assumes plane-parallel, homogeneous clouds. By using convolutional layers, the DNN method estimates cloud properties robustly, even for optically thick clouds, and can correct the 3D radiative transfer effects that would otherwise affect the radiance values.

scholarly journals Improving aerosol interaction with clouds and precipitation in a regional chemical weather modeling system

2015 ◽  
Vol 15 (11) ◽  
pp. 15755-15790
Author(s):  
C. Zhou ◽  
X. Zhang ◽  
S. Gong ◽  
Y. Wang ◽  
M. Xue
Keyword(s):  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Liquid Water Content ◽  
Time Step ◽  
Cloud Droplets ◽  
Weather Model ◽  
Weather Modeling ◽  
Almost All ◽  
Aerosol Activation ◽  
Precipitation Events

Abstract. A comprehensive aerosol–cloud–precipitation interaction (ACI) scheme has been developed under CMA chemical weather modeling system GRAPES/CUACE. Calculated by a sectional aerosol activation scheme based on the information of size and mass from CUACE and the thermal-dynamic and humid states from the weather model GRAPES at each time step, the cloud condensation nuclei (CCN) is fed online interactively into a two-moment cloud scheme (WDM6) and a convective parameterization to drive the cloud physics and precipitation formation processes. The modeling system has been applied to study the ACI for January 2013 when several persistent haze-fog events and eight precipitation events occurred. The results show that interactive aerosols with the WDM6 in GRAPES/CUACE obviously increase the total cloud water, liquid water content and cloud droplet number concentrations while decrease the mean diameter of cloud droplets with varying magnitudes of the changes in each case and region. These interactive micro-physical properties of clouds improve the calculation of their collection growth rates in some regions and hence the precipitation rate and distributions in the model, showing 24 to 48% enhancements of TS scoring for 6 h precipitation in almost all regions. The interactive aerosols with the WDM6 also reduce the regional mean bias of temperature by 3 °C during certain precipitation events, but the monthly means bias is only reduced by about 0.3 °C.

scholarly journals Thermodynamic properties and cloud droplet activation of a series of oxo-acids

2010 ◽  
Vol 10 (2) ◽  
pp. 3755-3805 ◽  
Author(s):  
M. Frosch ◽  
A. A. Zardini ◽  
S. M. Platt ◽  
L. Müller ◽  
M.-C. Reinnig ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Thermodynamic Properties ◽  
Vapor Pressure ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Dicarboxylic Acids ◽  
Atmospheric Particulate Matter ◽  
Flow Tube ◽  
Order Of Magnitude ◽  
Ccn Activity

Abstract. We have investigated the thermodynamic properties of four aliphatic oxo-dicarboyxlic acids identified or thought to be present in atmospheric particulate matter: oxosuccinic acid, 2-oxoglutaric acid, 3-oxoglutaric acid, and 4-oxopimelic acid. The compounds were characterized in terms of their cloud condensation nuclei (CCN) activity, vapor pressure, density, and tendency to decarboxylate in aqueous solution. We deployed a variety of experimental techniques and instruments: a CCN counter, a Tandem Differential Mobililty Analyzer (TDMA) coupled with a laminar flow-tube, and liquid chromatography/mass spectrometry (LC/MS). The presence of the oxo functional group in the α-position causes the vapor pressure of the compounds to diminish by an order of magnitude with respect to the parent dicarboxylic acid, while the CCN activity is similar or increased. Dicarboxylic acids with an oxo-group in the β-position were found to decarboxylate in aqueous solution.

scholarly journals Relationships between particles, cloud condensation nuclei and cloud droplet activation during the third Pallas Cloud Experiment

2012 ◽  
Vol 12 (6) ◽  
pp. 13691-13732
Author(s):  
T. Anttila ◽  
D. Brus ◽  
A. Jaatinen ◽  
A.-P. Hyvärinen ◽  
N. Kivekäs ◽  
...  
Keyword(s):  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Droplet Surface ◽  
The Arctic ◽  
Condensation Nuclei ◽  
Cloud Droplets ◽  
The Third ◽  
Droplet Activation ◽  
Experimental Values

Abstract. Concurrent measurement of aerosols, cloud condensation nuclei (CCN) and cloud droplet activation were carried out as a part of the third Pallas Cloud Experiment (PaCE-3) which took place at a ground based site located on northern Finland during the autumn of 2009. In this study, we investigate relationships between the aerosol properties, CCN and size resolved cloud droplet activation. During the investigated cloudy periods, the inferred number of cloud droplets (CDNC) varied typically between 50 and 150 cm−3 and displayed a linear correlation both with the number of particles having sizes over 100 nm and with the CCN concentrations at 0.4% supersaturation. Furthermore, the diameter corresponding to the 50% activation fraction, D50, was generally in the range of 80 to 120 nm. The measured CCN concentrations were compared with predictions of a numerical model which used the measured size distribution and size resolved hygroscopicity as input. Assuming that the droplet surface tension is equal to that of water, the measured and predicted CCN concentrations were generally within 30%. We also simulated size dependent cloud droplet activation with a previously developed air parcel model. By forcing the model to reproduce the experimental values of CDNC, adiabatic estimates for the updraft velocity and the maximum supersaturation reached in the clouds were derived. Performed sensitivity studies showed further that the observed variability in CDNC was driven mainly by changes in the particle size distribution while the variations in the updraft velocity and hygroscopicity contributed to a lesser extent. The results of the study corroborate conclusions of previous studies according to which the number of cloud droplets formed in clean air masses close to the Arctic is determined mainly by the number of available CCN.

Sign in / Sign up

Export Citation Format

Share Document