Mechanisms for the Influence from Ice Nucleus Aerosols on Clouds and Their Indirect Effects: Clous Modelling PDF Download
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Author: Deepak Waman
Publisher:
ISBN: 9789189187252
Category :
Languages : en
Pages : 0
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Book Description
The role of multiple groups of primary biological aerosol particles (PBAPs) as ice nucleating particles (INPs), and of ice formation processes such as time-dependent freezing of various INPs, and various secondary ice production (SIP) mechanisms in overall ice concentration has been evaluated in a range of cloud systems by simulating them numerically with the state-of-the-art 'Aerosol-Cloud' (AC) model in a 3D mesoscale domain. Also, the mechanisms of aerosol indirect effects (AIEs) arising from anthropogenic INPs, and the responses to these AIEs from time-dependent INP freezing and SIP processes are investigated in the simulated clouds. The cloud systems simulated with AC are: events of summertime deep convection observed over Oklahoma, USA during the Midlatitude Continental Convective Cloud Experiment (MC3E) in 2011 on 1) 11 May, and 2) 20 May, and wintertime 3) orographic clouds observed during the Atmospheric Radiation Measurement Cloud Aerosol Precipitation Experiment (ACAPEX) on 07 February 2015 over North California, and 4) supercooled layer clouds observed over Larkhill, UK, during the Aerosol Properties, Processes And Influences on the Earth's climate (APPRAISE) campaign on 18 February 2009. AC uses the dynamical core of the Weather Research and Forecasting (WRF) model, modified Geophysical Fluid Dynamic Laboratory (GFDL) radiation scheme, and hybrid bin-bulk microphysics scheme. AC is validated adequately with the coincident aircraft, ground-based, and satellite observations for all four cases. AC forms secondary ice through the Hallett-Mossop (HM) process of rime-splintering, and fragmentation during ice-ice collisions, raindrop freezing, and sublimation of dendritic snow and graupel. A measure of SIP is defined using the term 'ice enhancement' (IE) ratio which is the ratio between the number concentration of total ice particles and active INPs at cloud tops. For both cases in MC3E, overall, PBAPs have little effect (+1-6%) on the cloud-liquid (droplet mean sizes, number concentrations, and their water contents) properties, overall ice concentration, and on precipitation. AC predicts the activity of various INPs with an empirical parameterization (EP). The EP is modified to represent the time-dependent approach of INP freezing in light of our published laboratory observations. It is predicted that the time dependence of INP freezing is not the main cause for continuous ice nucleation and precipitation in all simulated cases. Rather, the main mechanism of precipitation formation is the combination of various SIP mechanisms (in convection) and recirculation-reactivation of dust particles (in APPRAISE layer cloud episode). Also, for all cases, the inclusion of time dependence of INP freezing causes little increase (about 10-20%) in the total ice concentration and ice from all SIP. Regarding SIP, in young developing convective clouds of MC3E (11 May), with tops > −15oC, the initial explosive growth is from the fast HM process, creating IE ratios as high as 103. By contrast, in mature convective clouds (tops
Author: Deepak Waman
Publisher:
ISBN: 9789189187252
Category :
Languages : en
Pages : 0
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Book Description
The role of multiple groups of primary biological aerosol particles (PBAPs) as ice nucleating particles (INPs), and of ice formation processes such as time-dependent freezing of various INPs, and various secondary ice production (SIP) mechanisms in overall ice concentration has been evaluated in a range of cloud systems by simulating them numerically with the state-of-the-art 'Aerosol-Cloud' (AC) model in a 3D mesoscale domain. Also, the mechanisms of aerosol indirect effects (AIEs) arising from anthropogenic INPs, and the responses to these AIEs from time-dependent INP freezing and SIP processes are investigated in the simulated clouds. The cloud systems simulated with AC are: events of summertime deep convection observed over Oklahoma, USA during the Midlatitude Continental Convective Cloud Experiment (MC3E) in 2011 on 1) 11 May, and 2) 20 May, and wintertime 3) orographic clouds observed during the Atmospheric Radiation Measurement Cloud Aerosol Precipitation Experiment (ACAPEX) on 07 February 2015 over North California, and 4) supercooled layer clouds observed over Larkhill, UK, during the Aerosol Properties, Processes And Influences on the Earth's climate (APPRAISE) campaign on 18 February 2009. AC uses the dynamical core of the Weather Research and Forecasting (WRF) model, modified Geophysical Fluid Dynamic Laboratory (GFDL) radiation scheme, and hybrid bin-bulk microphysics scheme. AC is validated adequately with the coincident aircraft, ground-based, and satellite observations for all four cases. AC forms secondary ice through the Hallett-Mossop (HM) process of rime-splintering, and fragmentation during ice-ice collisions, raindrop freezing, and sublimation of dendritic snow and graupel. A measure of SIP is defined using the term 'ice enhancement' (IE) ratio which is the ratio between the number concentration of total ice particles and active INPs at cloud tops. For both cases in MC3E, overall, PBAPs have little effect (+1-6%) on the cloud-liquid (droplet mean sizes, number concentrations, and their water contents) properties, overall ice concentration, and on precipitation. AC predicts the activity of various INPs with an empirical parameterization (EP). The EP is modified to represent the time-dependent approach of INP freezing in light of our published laboratory observations. It is predicted that the time dependence of INP freezing is not the main cause for continuous ice nucleation and precipitation in all simulated cases. Rather, the main mechanism of precipitation formation is the combination of various SIP mechanisms (in convection) and recirculation-reactivation of dust particles (in APPRAISE layer cloud episode). Also, for all cases, the inclusion of time dependence of INP freezing causes little increase (about 10-20%) in the total ice concentration and ice from all SIP. Regarding SIP, in young developing convective clouds of MC3E (11 May), with tops > −15oC, the initial explosive growth is from the fast HM process, creating IE ratios as high as 103. By contrast, in mature convective clouds (tops
Author: Deepak Waman
Publisher:
ISBN: 9789189187269
Category :
Languages : en
Pages : 0
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Book Description
The role of multiple groups of primary biological aerosol particles (PBAPs) as ice nucleating particles (INPs), and of ice formation processes such as time-dependent freezing of various INPs, and various secondary ice production (SIP) mechanisms in overall ice concentration has been evaluated in a range of cloud systems by simulating them numerically with the state-of-the-art 'Aerosol-Cloud' (AC) model in a 3D mesoscale domain. Also, the mechanisms of aerosol indirect effects (AIEs) arising from anthropogenic INPs, and the responses to these AIEs from time-dependent INP freezing and SIP processes are investigated in the simulated clouds. The cloud systems simulated with AC are: events of summertime deep convection observed over Oklahoma, USA during the Midlatitude Continental Convective Cloud Experiment (MC3E) in 2011 on 1) 11 May, and 2) 20 May, and wintertime 3) orographic clouds observed during the Atmospheric Radiation Measurement Cloud Aerosol Precipitation Experiment (ACAPEX) on 07 February 2015 over North California, and 4) supercooled layer clouds observed over Larkhill, UK, during the Aerosol Properties, Processes And Influences on the Earth's climate (APPRAISE) campaign on 18 February 2009. AC uses the dynamical core of the Weather Research and Forecasting (WRF) model, modified Geophysical Fluid Dynamic Laboratory (GFDL) radiation scheme, and hybrid bin-bulk microphysics scheme. AC is validated adequately with the coincident aircraft, ground-based, and satellite observations for all four cases. AC forms secondary ice through the Hallett-Mossop (HM) process of rime-splintering, and fragmentation during ice-ice collisions, raindrop freezing, and sublimation of dendritic snow and graupel. A measure of SIP is defined using the term 'ice enhancement' (IE) ratio which is the ratio between the number concentration of total ice particles and active INPs at cloud tops. For both cases in MC3E, overall, PBAPs have little effect (+1-6%) on the cloud-liquid (droplet mean sizes, number concentrations, and their water contents) properties, overall ice concentration, and on precipitation. AC predicts the activity of various INPs with an empirical parameterization (EP). The EP is modified to represent the time-dependent approach of INP freezing in light of our published laboratory observations. It is predicted that the time dependence of INP freezing is not the main cause for continuous ice nucleation and precipitation in all simulated cases. Rather, the main mechanism of precipitation formation is the combination of various SIP mechanisms (in convection) and recirculation-reactivation of dust particles (in APPRAISE layer cloud episode). Also, for all cases, the inclusion of time dependence of INP freezing causes little increase (about 10-20%) in the total ice concentration and ice from all SIP. Regarding SIP, in young developing convective clouds of MC3E (11 May), with tops > −15oC, the initial explosive growth is from the fast HM process, creating IE ratios as high as 103. By contrast, in mature convective clouds (tops
Author: Hsiang-He Lee
Publisher:
ISBN: 9781321363142
Category :
Languages : en
Pages :
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Book Description
The source-oriented Weather Research and Forecasting chemistry model (SOWC) was modified to include warm/cold cloud processes and applied to investigate 1) how source-oriented aerosols influence fog formation and optical properties in the atmosphere, 2) how aerosol mixing state influences cloud and ice formation and atmospheric optical properties during a winter storm, and 3) the direct, semi-direct, and indirect effects of long-range transport dust on severe weather over California and the Eastern Pacific. SOWC tracks 6-dimensional chemical variables (X, Z, Y, Size Bins, Source Types, Species) through an explicit simulation of atmospheric chemistry and physics. In this study, all aerosol source types can activate to form cloud condensation nuclei (CCN) based on the Köhler theory, but the dust is the only source of ice nuclei (IN). Furthermore, a new source-oriented cloud module in the two-moment Purdue Lin microphysics scheme, and a new module with all source-oriented hydrometeors (cloud, ice, rain, snow and graupel) in the Morrison two-moment microphysics scheme were implemented into the SOWC model to study fog events and winter storm cases, respectively. In Chapter 2, the enhanced SOWC model was used to study a fog event that occurred on January 17th, 2011, in the Central Valley of California. The SOWC reasonably portrays the spatial distribution and duration of the fog event consistent with observations. The source-oriented mixture representation of particles reduced cloud droplet number relative to the internal mixture approach that artificially coats hydrophobic particles with hygroscopic components. The fraction of aerosols activating into CCN at a supersaturation of 0.5% in the Central Valley decreased from 86% in the internal mixture model to 68% in the source-oriented model. This increased the surface energy flux by 3-5 W m-2 and surface temperature by as much as 0.15 K. In Chapter 3, the enhanced SOWC model was used to study a winter storm that occurred on March 6th, 2011, in California. Compared to ground based observations, SOWC with the modified Morrison microphysics scheme and modified Goddard radiation schemes predicted reasonable precipitation, but the onset of precipitation is delayed by 5 hours. Immersion freezing was the main mechanism for ice nuclei formation. Secondary coatings on dust particles increased IN from immersion freezing but decreased IN from contact freezing. Increasing CCN and IN in the internal mixing experiment produced more ice crystals and cloud droplets but did not significantly alter total perception under the conditions studied. However, because of the reducing riming efficiency from snow to graupel in the source-oriented mixing experiment, it resulted more snowfall (less rainfall) on the ground, especially over the mountain area. In Chapter 4, the SOWC model was used to understand the direct, semi-direct, and indirect effects of long-range transport dust on severe weather over Eastern Pacific Ocean. The maximum averaged IN nucleation rate increased 36% after adding long-range transport dust. Because clouds in mid-latitude originate precipitately via the ice phase, an increase in IN can enhance ice formation from supercooled water by heterogenetic freezing (mainly contact freezing) and then to alter hydrometer water amount. Adding long-range transport dust increased the mixing ratio and number concentration for almost all hydrometers. However, the changes of adding local dust in local+LR_dust from LR_dust is more complicated due to the importance of hydrometers in the cumulus scheme. The change in the strength of convection after adding long-range transport dust (or local dust) also produces a noticeable distinction in the precipitation pattern, but the total precipitation did not have major difference after adding long-range transport dust (or local dust).
Author: Constantin Andronache
Publisher: Elsevier
ISBN: 012810550X
Category : Science
Languages : en
Pages : 302
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Book Description
Mixed-Phase Clouds: Observations and Modeling presents advanced research topics on mixed-phase clouds. As the societal impacts of extreme weather and its forecasting grow, there is a continuous need to refine atmospheric observations, techniques and numerical models. Understanding the role of clouds in the atmosphere is increasingly vital for current applications, such as prediction and prevention of aircraft icing, weather modification, and the assessment of the effects of cloud phase partition in climate models. This book provides the essential information needed to address these problems with a focus on current observations, simulations and applications. Provides in-depth knowledge and simulation of mixed-phase clouds over many regions of Earth, explaining their role in weather and climate Features current research examples and case studies, including those on advanced research methods from authors with experience in both academia and the industry Discusses the latest advances in this subject area, providing the reader with access to best practices for remote sensing and numerical modeling
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
This 3-year project has studied how aerosol pollution influences glaciated clouds. The tool applied has been an 'aerosol-cloud model'. It is a type of Cloud-System Resolving Model (CSRM) modified to include 2-moment bulk microphysics and 7 aerosol species, as described by Phillips et al. (2009, 2013). The study has been done by, first, improving the model and then performing sensitivity studies with validated simulations of a couple of observed cases from ARM. These are namely the Tropical Warm Pool International Cloud Experiment (TWP-ICE) over the tropical west Pacific and the Cloud and Land Surface Interaction Campaign (CLASIC) over Oklahoma. During the project, sensitivity tests with the model showed that in continental clouds, extra liquid aerosols (soluble aerosol material) from pollution inhibited warm rain processes for precipitation production. This promoted homogeneous freezing of cloud droplets and aerosols. Mass and number concentrations of cloud-ice particles were boosted. The mean sizes of cloud-ice particles were reduced by the pollution. Hence, the lifetime of glaciated clouds, especially ice-only clouds, was augmented due to inhibition of sedimentation and ice-ice aggregation. Latent heat released from extra homogeneous freezing invigorated convective updrafts, and raised their maximum cloud-tops, when aerosol pollution was included. In the particular cases simulated in the project, the aerosol indirect effect of glaciated clouds was twice than of (warm) water clouds. This was because glaciated clouds are higher in the troposphere than water clouds and have the first interaction with incoming solar radiation. Ice-only clouds caused solar cooling by becoming more extensive as a result of aerosol pollution. This 'lifetime indirect effect' of ice-only clouds was due to higher numbers of homogeneously nucleated ice crystals causing a reduction in their mean size, slowing the ice-crystal process of snow production and slowing sedimentation. In addition to the known indirect effects (glaciation, riming and thermodynamic), new indirect effects were discovered and quantified due to responses of sedimentation, aggregation and coalescence in glaciated clouds to changing aerosol conditions. In summary, the change in horizontal extent of the glaciated clouds ('lifetime indirect effects'), especially of ice-only clouds, was seen to be of higher importance in regulating aerosol indirect effects than changes in cloud properties ('cloud albedo indirect effects').
Author: Partha Sarathi Bhattacharjee
Publisher:
ISBN:
Category : Atmospheric aerosols
Languages : en
Pages : 0
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Book Description
Increasing human population and rapid urbanization in the last two decades have caused a sharp rise in anthropogenic aerosols particularly over South and East Asia. Numerous studies have shown that aerosols play an important role in climate change through their interaction with the global water and energy cycles. Thus Aerosol-cloud-radiation-monsoon interaction related droughts and floods are two of the most serious environmental hazards confronting more than 60% of the population of the world living in the Asian monsoon countries. General circulation models (GCMs) are an important tool for understanding the climate response to changes in the amounts and composition of aerosols due to evolving use of fossil and biomass fuels. This dissertation attempt to get an insight into the aerosol-cloud interaction and study impacts of aerosol forcing, with particular emphasis on the interaction of aerosol with monsoon water cycle. NASA Goddard Earth Observing System (GEOS) version 4 General Circulation Model (called GEOS4-GCM) with moist convection of Relaxed Arakawa-Schubert Scheme (McRAS) clouds and state-of-the-art parameterization of cloud microphysical process is used this study. A Single Column version (SCM) of the model is used to evaluate various parameterization schemes by comparing against in-situ and satellite observations. The model simulated realistic annual mean and annual cycles of cloud water, cloud optical thickness, cloud drop number concentration and effective radius without showing any systematic biases. GCM version of the model is used to study aerosol induced anomalies during summer months (June-August) particularly focusing over Indian monsoon. The individual aerosol effects (direct and indirect) and their combination show different impacts on radiation as well as on cloud microphysics, precipitation and circulation. However, complexities of nucleation of ice clouds in the model result not enough aerosols were acting as ice nuclei, which led to incomplete understanding of indirect effect in the atmosphere.
Author: Alexander P. Khain
Publisher: Cambridge University Press
ISBN: 1108646956
Category : Science
Languages : en
Pages : 644
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Book Description
This book presents the most comprehensive and systematic description currently available of both classical and novel theories of cloud processes, providing a much-needed link between cloud theory, observation, experimental results, and cloud modeling. This volume shows why and how modern models serve as a major tool of investigation of cloud processes responsible for atmospheric phenomena, including climate change. It systematically describes classical as well as recent advancements in cloud physics, including cloud-aerosol interaction; collisions of particles in turbulent clouds; and the formation of multiphase cloud particles. As the first of its kind to serve as a practical guide for using state-of-the-art numerical cloud models, major emphasis is placed on explaining how microphysical processes are treated in modern numerical cloud resolving models. The book will be a valuable resource for advanced students, researchers and numerical model designers in cloud physics, atmospheric science, meteorology, and environmental science.
Author: S Ramachandran
Publisher: CRC Press
ISBN: 1498750745
Category : Science
Languages : en
Pages : 295
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Book Description
This book includes basic knowledge and understanding on the characteristics of aerosols over the continent and oceanic regions, their composition, residence times, sinks and size distributions, and their effects in the radiative transfer and climate of Earth.
Author: PRUPPACHER
Publisher: Birkhäuser
ISBN:
Category : Juvenile Nonfiction
Languages : en
Pages : 386
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Book Description
Author: Daniel Alexander Rothenberg
Publisher:
ISBN:
Category :
Languages : en
Pages : 189
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Book Description
The influence of anthropogenic aerosol emissions on the optical properties of clouds and the radiative forcing arising from these interactions, known as the aerosol indirect effect on climate, constitutes a fundamental uncertainty in our understanding of 2 0 th century climate change. In this dissertation, we investigate the role of a keystone physical process, droplet activation, in contributing to this uncertainty. The first half of the ensuing work focuses on the parameterization of this process in global model, assessing both existing schemes and developing a novel one. The second half then quantifies the influence of activation by using a suite of aerosol-climate models which include a complete description of the physics which give rise to the indirect effect. Parameterizations of droplet activation perform well for idealized single-mode aerosol populations, but show systematic biases in high-pollution, weak-updraft regimes. These are exacerbated when the aerosol in question is a complex mixture. We show that estimates of droplet nucleation are highly sensitive to changes in the accumulation mode size and number concentration; this mode is itself sensitive to anthropogenic aerosol emissions, which potentially further biases modeled cloud droplet number. Using a model emulation technique, we develop a framework for building efficient metamodels of activation, which greatly reduce the mean error in droplet number predicted across regimes. The biases in these parameterizations raise questions the influence of activation on the indirect effect. Using different schemes, we calculate a spread of 1 W m- 2 in the indirect effect, which we show is equal to the spread computed from an independent suite of global models with different aerosol and physics modules. The estimated indirect effect scales more strongly with the baseline cloud droplet number concentration simulated by each model than by its change from pre-industrial to present day, indicating a strong saturation effect. While present-day estimates of aerosol-cloud interactions derived from satellite-based instruments are inadequate at constraining the pre-industrial cloud droplet burden, we show that process-based measurements could overcome this problem.
