Download or read book Investigation of Aerosol Optical Properties on Regional Climate Forcing and Spatial and Temporal Distributions of Aerosol and Ozone Associated with the Antarctic Polar Vortex Processes written by Jung-Sun Im and published by . This book was released on 2002 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: aerosol, hygroscopic growth factor, black carbon, ozone depletion, polar stratospheric clouds.
Download or read book Investigation of Aerosol Optical Properties on Regional Climate Forcing and Spatial and Temporal Distributions of Aerosol and Ozone Associated with the Antarctic Polar Vortex Processes written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosols influence Earth's heat budget both directly by scattering and absorbing sunlight, and indirectly by acting as nuclei for cloud droplets. To reduce the uncertainties of current estimates of aerosol climate forcing, aerosol optical properties relevant to the computation of direct radiative forcing were measured at a regionally representative site near Mount Mitchell, North Carolina. On the basis of these measurements and model calculations, we have studied (1) the effects of relative humidity (RH) on aerosol optical properties and direct aerosol radiative forcing and (2) the influence of long-range transport on black carbon (BC) concentrations, its seasonal and weekly patterns, and the effects of BC on the regional climate of the southeastern US. The light scattering of aerosol is strongly dependent on RH at which it is measured, due to hygroscopic growth nature of most atmospheric aerosols. In this study, the hygroscopic growth factor (ratio of total scattering coefficient at RH=80% to that at RH=30%) was calculated to be almost constant value of 1.60 +/- 0.01 for polluted, marine, and continental air masses. In addition, it was found that as the RH increased from 30% to 80%, the backscatter fraction decreased by 23%. The patterns of direct radiative climate forcing by aerosols for various values of RH were similar for the three air masses, but the magnitudes of the forcing were larger for polluted air masses than for marine and continental air masses by a factor of nearly 2 due to higher sulfate concentration in polluted air masses. The averaged forcing for all the observed ambient RHs was -2.9 W m^( -2) (the negative forcing of -3.2 by aerosol scattering plus the positive forcing of +0.3 by aerosol absorption) for polluted air masses, -1.4 W m^( -2) ( -1.5 plus +0.1) for marine air masses, and -1.5 W m^( -2) ( -1.6 plus +0.1) for continental air masses. The BC mass concentration of the southeastern US showed the highest average concentration in polluted air mas.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2003 with total page 860 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Atmospheric Aerosols written by Hayder Abdul-Razzak and published by BoD – Books on Demand. This book was released on 2012-09-12 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book is divided into two sections. The first section presents characterization of atmospheric aerosols and their impact on regional climate from East Asia to the Pacific. Ground-based, air-born, and satellite data were collected and analyzed. Detailed information about measurement techniques and atmospheric conditions were provided as well. In the second section, authors provide detailed information about the organic and inorganic constituents of atmospheric aerosols. They discuss the chemical and physical processes, temporal and spatial distribution, emissions, formation, and transportation of aerosol particles. In addition, new measurement techniques are introduced. This book hopes to serve as a useful resource to resolve some of the issues associated with the complex nature of the interaction between atmospheric aerosols and climatology.
Download or read book Atmospheric Aerosol Properties and Climate Impacts written by and published by . This book was released on 2009 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterizing the Spatial and Temporal Distribution of Aerosol Optical Thickness Over the Atlantic Basin Utilizing Goes 8 Multispectral Data written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-09-14 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, modeling and analysis efforts have suggested that the direct and indirect radiative effects of both anthropogenic and natural aerosols play a major role in the radiative balance of the earth and are an important factor in climate change calculations. The direct effects of aerosols on radiation and indirect effects on cloud properties are not well understood at this time. In order to improve the characterization of aerosols within climate models it is important to accurately parameterize aerosol forcing mechanisms at the local, regional, and global scales. This includes gaining information on the spatial and temporal distribution of aerosols, transport regimes and mechanisms, aerosol optical thickness, and size distributions. Although there is an expanding global network of ground measurements of aerosol optical thickness and size distribution at specific locations, satellite data must be utilized to characterize the spatial and temporal extent of aerosols and transport regimes on regional and global scales. This study was part of a collaborative effort to characterize aerosol radiative forcing over the Atlantic basin associated with the following three major aerosol components in this region: urban/sulfate, Saharan dust, and biomass burning. In-situ ground measurements obtained by a network of sun photometers during the Smoke Clouds and Radiation Experiment in Brazil (SCAR-B) and the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) were utilized to develop, calibrate, and validate a Geostationary Operational Environmental Satellite (GOES)-8 aerosol optical thickness (AOT) product. Regional implementation of the GOES-8 AOT product was used to augment point source measurements to gain a better understanding of the spatial and temporal distributions of Atlantic basin aerosols during SCAR-B and TARFOX.Fox, Robert and Prins, Elaine Mae and Feltz, Joleen M.Goddard Space Flight CenterSIZE DISTRIBUTION; SPATIAL DISTRIBUTION; AEROSOLS
Download or read book Atmospheric Aerosol Properties and Climate Impacts written by Mian Chin and published by DIANE Publishing. This book was released on 2009-05 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Synthesis and Assessment Product (SAP) critically reviews current knowledge about global distributions and properties of atmospheric aerosols, as they relate to aerosol impacts on climate. It assesses possible next steps aimed at substantially reducing uncertainties in aerosol radiative forcing estimates. Current measurement techniques and modeling approaches are summarized, providing context. The objectives of this report are: (1) to promote a consensus about the knowledge base for climate change decision support; and (2) to provide a synthesis and integration of the current knowledge of the climate-relevant impacts of anthropogenic aerosols. Illustrations.
Download or read book Atmospheric Aerosols written by S Ramachandran and published by CRC Press. This book was released on 2018-09-03 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Atmospheric Aerosols Their Optical Properties and Effects written by and published by . This book was released on 1976 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Aerosol Optical and Chemical Properties Using Humidity Controlled Cavity Ring Down Spectroscopy written by and published by . This book was released on 2017 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientists have been observing a change in the climate since the beginning of the 20th century that cannot be attributed to any of the natural influences of the past. Natural and anthropogenic substances and processes perturb the Earth's energy budget, contributing to climate change. In particular, aerosols (particles suspended in air) have long been recognized to be important in processes throughout the atmosphere that affect climate. They directly influence the radiative balance of the Earth's atmosphere, affect cloud formation and properties, and are also key air pollutants that contribute to a variety of respiratory and cardiovascular diseases. Despite their importance, aerosol particles are less well-characterized than greenhouse gases with respect to their sources, temporal and spatial concentration distribution, and physical and chemical properties. This uncertainty is mainly caused by the variable and insufficiently understood sources, formation and transformation processes, and complex composition of atmospheric particles. Instruments that can precisely and accurately measure and characterize the aerosol physical and chemical properties are in great demand. Atmospheric relative humidity (RH) has a crucial impact on the particles' optical properties; the RH dependence of the particle extinction coefficient is an important parameter for radiative forcing and thus climate change modeling. In this work a Humidity-Controlled Cavity Ring-Down (HC-CRD) aerosol optical instrument is described and its ability to measure RH dependent extinction coefficients and related hygroscopicity parameters is characterized.
Download or read book The Stratospheric Aerosol Layer written by R.C. Whitten and published by Springer Science & Business Media. This book was released on 2013-03-07 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is now a quarter of a century since Junge and his coworkers recovered the first sample from the sulfate aerosol layer in the stratosphere. Since that time vast strides have been made in determining its physical properties and morphology. These investigations have been performed with instruments on board aircraft and balloon platforms as in the early days, with ground-based lidar (optical radar), and most recently with satellite-borne optical instruments. It will become evident in Chapter 2 that in situ measurements by aircI'aft and ,balloon sensors complement rather than duplicate the remote techniques (lidar and satellite). Hence future programs will probably continue to utilize direct as well as indirect experimental techniques. Concurrently, with the observations of the gross properties of the aerosol layer, la~oratory and theoretical studies have sought to elucidate the chemical and micro physical processes which influence the formation and growth of the aerosol par ticles. The laboratory investigations have included studies of gas phase chemistry, and particle nucleation and growth mechanisms. Theoretical studies have revolved mainly around a series of models developed by atmospheric scientists. The earliest of these models was constructed by Junge and his colleagues. With the advent of third- and fourth-generation computers, the capacity to solve the quite complex continuity equations whi~h govern particle formation, growth, and removal has ad vanced to the point where most of the particle properties can be simulated with reasonable confidence.
Download or read book Aerosol Surface and Cloud Retrieval Using Passive Remote Sensing Over the Arctic written by Soheila Jafariserajehlou and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The lack knowledge of aerosol optical properties is one of the sources of uncertainty in assessment and projections of the evolution of climate change and the phenomenon of Arctic Amplification. The spatial and temporal change of microphysical, chemical and optical properties of aerosols in the Arctic and the induced effects through direct and indirect radiative forcing of aerosols remain an open question. The cause of this gap in our understanding and therefore in the global aerosol optical thickness (AOT) maps is associated with the difficulty of retrieving aerosol properties over bright surfaces covered with snow and ice. Decoupling a strong surface signal from that of aerosol in the measured top-of-atmosphere reflectance is challenging and still hampered due to remaining unresolved issues in state-of-the-art algorithms. Despite the promising performance of previously-developed methods and ongoing research, there is no published long-term AOT product over polar regions (over land and ocean) to be used for climate studies. In this work, to extend our knowledge about the open issues and improve the existing algorithms, first we focus on the two major obstacles in the retrieval of AOT over snow/ice surfaces: i) cloud identification, and ii) surface properties; Second, we apply the outcome of studying the two mentioned prerequisites to improve the previously-developed aerosol retrieval algorithm called AEROSNOW and create a long-term data record for aerosol optical thickness over the Arctic circle. In the framework of this work, a new cloud identification algorithm called the AATSR/SLSTR Cloud Identification Algorithm (ASCIA) has been developed to screen cloudy scenes in observations of Advanced Along-Track Scanning Radiometer (AATSR) on-board ENVISAT as well as its successor Sea and Land Surface Temperature Radiometer (SLSTR) on-board Sentinel-3. The cloud detection results are verified by comparing them with available cloud products over the Arctic. Furthermore, the cloud product from ASCIA is validated using the ground-based measurements SYNOP, resulting in a promising agreement. In general, ASCIA shows an improved performance in comparison with other algorithms applied to AATSR measurements over snow/ice. For the study of snow surface properties, the reflectance is simulated in a snow-atmosphere system, using the SCIATRAN radiative transfer model, and the results are compared with those of airborne measurements. A sensitivity study is conducted to highlight the importance of having a priori knowledge about snow morphology (size and shape) and atmospheric parameters to minimise the difference between simulated and real world reflectance. The absolute difference between the modelled results and measurements in off-glint regions is generally small and promising. In the final step, we apply the outcome of previous steps in the AEROSNOW algorithm as far as possible within the scope of this work and retrieve AOT over the Arctic circle for the 2002-2012 period with the spatial resolution of 1 km2. The retrieved AOT is validated using ground-based measurements AErosol RObotic NETwork (AERONET). The results of validation are promising and show the successful performance of the algorithm especially during haze episodes. However, in some cases large differences exist between the retrieved AOT and AERONET measurements for which more statistical and physical analysis are necessary to better understand the cause. Nevertheless, the long-term data record and validation produced hold significant value as are the first attempt to better understand the role of aerosols in the Arctic Amplification over land and ocean on the full Arctic scale.
Download or read book Meteorology of the Southern Hemisphere written by David Karoly and published by Springer. This book was released on 2015-04-03 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book looks at the circulation features of the Southern Hemisphere, both for the atmosphere and oceans. It includes observational techniques based on satellites, anchored and drifting buoys, and the research carried out at research stations in the Southern Hemisphere. The book was originally published in 1972 by the American Meteorological Society. It has been revised and updated in 1999, following the expansion of research bases and the development of research in the region at the time.
Download or read book Investigation of Aerosol Sources Lifetime and Radiative Forcing Through Multi Instrument Data Assimilation written by Juli Irene Rubin and published by . This book was released on 2012 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: Global-scale atmospheric models play an important role in predicting atmospheric aerosol and the corresponding radiative forcing. Although atmospheric models are important tools, there is large uncertainty associated with aerosol predictions due to uncertainty in aerosol representation within the models. As a result, aerosols and their influence on the Earth's energy balance are considered one of the largest uncertainties in understanding climate change. Given the importance of simulating aerosol for understanding global climate change, it is evident that alternative methods are needed to reduce the effect of the uncertainties associated with aerosol representation and enhance the fidelity of the aerosol models. The goal of this research is to produce aerosol fields with reduced uncertainty by constraining model predictions with observations, using a technique known as data assimilation. The results from the aerosol assimilation are used to investigate aerosol sources, lifetime, and shortwave radiative forcing. Two new aerosol data assimilations are presented as part of this work with both assimilations making use of an Ensemble Kalman Filter (EnKF) and the National Center for Atmospheric Research's (NCAR) community atmosphere model (CAM) with 60 ensemble members. The first assimilation involves the joint adjustment of the amount of atmospheric aerosol and the relative amount of fine and coarse aerosol using observations of aerosol optical depth (AOD) and angstrom exponent from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS). Both the amount and relative contribution of fine and coarse aerosol were identified as key parameters for determining aerosol radiative forcing and, therefore, accurately determining these parameters is desirable. The second assimilation presented as part of this work is similar to the first with the addition of a vertical redistribution of coarse aerosol using vertical extinction observations from NASA's Cloud-Aerosol LIDAR and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. Studies have shown that the atmospheric lifetime of aerosol is tightly coupled to the vertical profile, therefore, it is expected that vertical adjustments will further reduce aerosol uncertainty, especially in coarse aerosol. Similar to aerosol amount and size, lifetime is important for properly quantifying radiative forcing as it determines the time an aerosol has to impact the climate and influences the horizontal distribution of aerosol that is highly heterogenous in space and time. The two presented assimilations are run for the year 2007 and results are compared against a control run simulation as well observations of AOD, angstrom exponent, and fine aerosol contributions from MODIS and NASA's Aerosol Robotic Network (AERONET). Through the comparison, it is demonstrated that the presented assimilations are able to reduce the model bias with an increase in the predicted aerosol optical depth. The globally averaged control run AOD prediction for 2007 is 0.086(± 0.06). The globally average AOD predictions for the amount and size assimilation and vertical assimilation are 0.115(± 0.05), 0.140(± 0.05), respectively. This is compared to globally averaged MODIS observations of 0.161(± 0.09). Over-ocean averaged angstrom exponent predictions from the control run are 0.65(± 0.35) while the size and amount and vertical assimilation predictions are 0.68 (± 0.15) and 0.66 (± 0.15), respectively. This is compared to globally averaged MODIS observations of 0.65(± 0.30). While it is difficult to determine improvements in angstrom exponent predictions based on the global average, clear reductions in regional biases were observed. Aerosol predictions are also compared to ground-based AERONET observations by site category, including desert dust, biomass burning, rural, industrial pollution, polluted marine, and dirty pollution. While the rural sites have statistically similar averaged AOD values across simulations, improvements are found for the other site categories in the assimilation runs with higher average AOD values and greater temporal variability. In addition to AOD comparison, the predicted amount of AOD due to fine aerosol is compared to AERONET observations by site category. The greatest reduction in bias is observed for polluted marine sites with the assimilation runs predicting a smaller fine aerosol contribution than the control simulation. Size-related observations are concentrated over ocean regions, therefore, the greatest impact of the assimilation with respect to size is expected for marine sites. Additionally, the positive bias in fine aerosol contribution predicted at dusty sites is reduced the most in the vertical assimilation with dust being mostly coarse in size. The adjustments to the vertical profile of coarse aerosol in the vertical assimilation further reduce bias for coarse dominated sites. The results of the assimilation are used to quantify the contribution of anthropogenic aerosol to AOD. Globally averaged, the anthropogenic contribution to AOD is 38.8 percent for the control simulation, 47.6 percent for the amount and size assimilation and 49.5 percent from the vertical assimilation. These results are comparable to previously published anthropogenic AOD percentages which range from 41 to 72 percent (IPCC 2007). Additionally, aerosol loss processes and lifetime are analyzed. The dominant loss processes are condensational growth for nucleation mode aerosol (fine, 1 & mum). The longest aerosol lifetimes are found in the vertical assimilation with most aerosol species showing better comparison to reported AEROCOM lifetimes, except for sulfate. In particular, the lifetimes of coarse mode dust and sea salt increased in the vertical adjustment assimilation, reducing the negative aerosol optical depth bias, especially in dusty regions. The predicted sulfate lifetime is double the reported AEROCOM value and may be the cause of some positive AOD bias regions in the Northern hemisphere predicted in the model runs. The solar direct radiative forcing (DRE) is calculated using the predicted aerosol fields with the DRE including the effects of both anthropogenic and natural aerosol. Uncertainties in DRE for the assimilation runs are determined using the 60 member ensemble spread. Globally averaged DRE values are -1.9 W/m2, -5.2(± 0.51) W/m2, and -7.2(± 0.94) W/m2, for the control, amount and size and vertical assimilation, respectively. The predicted DRE from the amount and size assimilation compares the best to previously published estimates. Additionally, the calculated anthropogenic contribution to AOD is used in conjunction with the DRE estimates to calculate shortwave anthropogenic direct radiative forcing estimates with predicted values of -0.77, -2.3(± 0.64) and -3.2(± 0.7) W/m2 for the control, amount and size assimilation and vertical assimilation, respectively.
Download or read book The Ocean and Cryosphere in a Changing Climate written by Intergovernmental Panel on Climate Change (IPCC) and published by Cambridge University Press. This book was released on 2022-04-30 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.
Download or read book Thriving on Our Changing Planet A Decadal Strategy for Earth Observation from Space written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2019-06-18 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: We live on a dynamic Earth shaped by both natural processes and the impacts of humans on their environment. It is in our collective interest to observe and understand our planet, and to predict future behavior to the extent possible, in order to effectively manage resources, successfully respond to threats from natural and human-induced environmental change, and capitalize on the opportunities â€" social, economic, security, and more â€" that such knowledge can bring. By continuously monitoring and exploring Earth, developing a deep understanding of its evolving behavior, and characterizing the processes that shape and reshape the environment in which we live, we not only advance knowledge and basic discovery about our planet, but we further develop the foundation upon which benefits to society are built. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space (National Academies Press, 2018) provides detailed guidance on how relevant federal agencies can ensure that the United States receives the maximum benefit from its investments in Earth observations from space, while operating within realistic cost constraints. This short booklet, designed to be accessible to the general public, provides a summary of the key ideas and recommendations from the full decadal survey report.
Download or read book Aerosol Cloud Climate Interactions written by Peter V. Hobbs and published by Academic Press. This book was released on 1993-07-22 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosol and clouds play important roles in determining the earth's climate, in ways that we are only beginning to comprehend. In conjunction with molecular scattering from gases, aerosol and clouds determine in part what fraction of solar radiation reaches the earth's surface, and what fraction of the longwave radiation from the earth escapes to space. This book provides an overview of the latest research on atmospheric aerosol and clouds and their effects on global climate. Subjects reviewed include the direct and indirect effects of aerosol on climate, the radiative properties of clouds and their effects on the Earth's radiation balance, the incorporation of cloud effects in numerical weather prediction models, and stratospheric aerosol and clouds.
