Science.gov

Sample records for substituting aerosol geoengineering

  1. The economics (or lack thereof) of aerosol geoengineering

    NASA Astrophysics Data System (ADS)

    Goes, M.; Keller, K.; Tuana, N.

    2009-04-01

    Anthropogenic greenhouse gas emissions are changing the Earth's climate and impose substantial risks for current and future generations. What are scientifically sound, economically viable, and ethically defendable strategies to manage these climate risks? Ratified international agreements call for a reduction of greenhouse gas emissions to avoid dangerous anthropogenic interference with the climate system. Recent proposals, however, call for the deployment of a different approach: to geoengineer climate by injecting aerosol precursors into the stratosphere. Published economic studies typically suggest that substituting aerosol geoengineering for abatement of carbon dioxide emissions results in large net monetary benefits. However, these studies neglect the risks of aerosol geoengineering due to (i) the potential for future geoengineering failures and (ii) the negative impacts associated with the aerosol forcing. Here we use a simple integrated assessment model of climate change to analyze potential economic impacts of aerosol geoengineering strategies over a wide range of uncertain parameters such as climate sensitivity, the economic damages due to climate change, and the economic damages due to aerosol geoengineering forcing. The simplicity of the model provides the advantages of parsimony and transparency, but it also imposes severe caveats on the interpretation of the results. For example, the analysis is based on a globally aggregated model and is hence silent on the question of intragenerational distribution of costs and benefits. In addition, the analysis neglects the effects of endogenous learning about the climate system. We show that the risks associated with a future geoengineering failure and negative impacts of aerosol forcings can cause geoenginering strategies to fail an economic cost-benefit test. One key to this finding is that a geoengineering failure would lead to dramatic and abrupt climatic changes. The monetary damages due to this failure can

  2. The economics and ethics of aerosol geoengineering strategies

    NASA Astrophysics Data System (ADS)

    Goes, Marlos; Keller, Klaus; Tuana, Nancy

    2010-05-01

    Anthropogenic greenhouse gas emissions are changing the Earth's climate and impose substantial risks for current and future generations. What are scientifically sound, economically viable, and ethically defendable strategies to manage these climate risks? Ratified international agreements call for a reduction of greenhouse gas emissions to avoid dangerous anthropogenic interference with the climate system. Recent proposals, however, call for a different approach: geoengineering climate by injecting aerosol precursors into the stratosphere. Published economic studies typically neglect the risks of aerosol geoengineering due to (i) a potential failure to sustain the aerosol forcing and (ii) due to potential negative impacts associated with aerosol forcings. Here we use a simple integrated assessment model of climate change to analyze potential economic impacts of aerosol geoengineering strategies over a wide range of uncertain parameters such as climate sensitivity, the economic damages due to climate change, and the economic damages due to aerosol geoengineering forcings. The simplicity of the model provides the advantages of parsimony and transparency, but it also imposes considerable caveats. For example, the analysis is based on a globally aggregated model and is hence silent on intragenerational distribution of costs and benefits. In addition, the analysis neglects the effects of future learning and is based on a simple representation of climate change impacts. We use this integrated assessment model to show three main points. First, substituting aerosol geoengineering for the reduction of greenhouse gas emissions can fail the test of economic efficiency. One key to this finding is that a failure to sustain the aerosol forcing can lead to sizeable and abrupt climatic changes. The monetary damages due to such a discontinuous aerosol geoengineering can dominate the cost-benefit analysis because the monetary damages of climate change are expected to increase with

  3. Stratospheric aerosol geoengineering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Robock, Alan

    2015-03-30

    The Geoengineering Model Intercomparison Project, conducting climate model experiments with standard stratospheric aerosol injection scenarios, has found that insolation reduction could keep the global average temperature constant, but global average precipitation would reduce, particularly in summer monsoon regions around the world. Temperature changes would also not be uniform; the tropics would cool, but high latitudes would warm, with continuing, but reduced sea ice and ice sheet melting. Temperature extremes would still increase, but not as much as without geoengineering. If geoengineering were halted all at once, there would be rapid temperature and precipitation increases at 5–10 times the rates frommore » gradual global warming. The prospect of geoengineering working may reduce the current drive toward reducing greenhouse gas emissions, and there are concerns about commercial or military control. Because geoengineering cannot safely address climate change, global efforts to reduce greenhouse gas emissions and to adapt are crucial to address anthropogenic global warming.« less

  4. Does Aerosol Geoengineering the Earth's Climate Pass a Cost-Benefit Test?

    NASA Astrophysics Data System (ADS)

    Keller, K.; Urban, N.; Tuana, N.

    2007-12-01

    Anthropogenic carbon dioxide (CO2) emissions are changing the Earth's climate with potentially dangerous consequences. Ratified international agreements call for a reduction of CO2 emissions to avoid dangerous anthropogenic interference with the climate system. Recent studies have, however, proposed an alternative strategy: to geoengineer Earth's climate by injecting aerosol precursors into the stratosphere. It is often claimed that aerosol geoengineering would provide net economic benefits because geoengineering requires far lower near-term investments compared to deep cuts in CO2 emissions. However, aerosol geoengineering projects can also cause nontrivial economic costs. This is because aerosol geoengineering hinges on successfully counterbalancing the forcing effects of CO2 emissions (which decay over centuries) with the forcing effects of aerosol emissions (which decay within years). A failure to maintain this delicate balance can lead to abrupt climatic changes, with potentially substantial economic damages. Deferring cuts in CO2 emissions in favor of aerosol geoengineering is hence a deeply uncertain gamble, as it requires so far unknown institutions to reliably control aerosol forcings over centuries. Here we use a simple economic model to evaluate potential costs and benefits of aerosol geoengineering for a wide range of the deeply uncertain parameters. We show that aerosol geoengineering projects may cause economic damages that can far exceed the benefits and may hence fail a cost-benefit test.

  5. Detecting sulphate aerosol geoengineering with different methods

    DOE PAGES

    Lo, Y. T. Eunice; Charlton-Perez, Andrew J.; Lott, Fraser C.; ...

    2016-12-15

    Sulphate aerosol injection has been widely discussed as a possible way to engineer future climate. Monitoring it would require detecting its effects amidst internal variability and in the presence of other external forcings. Here, we investigate how the use of different detection methods and filtering techniques affects the detectability of sulphate aerosol geoengineering in annual-mean global-mean near-surface air temperature. This is done by assuming a future scenario that injects 5 Tg yr -1 of sulphur dioxide into the stratosphere and cross-comparing simulations from 5 climate models. 64% of the studied comparisons would require 25 years or more for detection whenmore » no filter and the multi-variate method that has been extensively used for attributing climate change are used, while 66% of the same comparisons would require fewer than 10 years for detection using a trend-based filter. This then highlights the high sensitivity of sulphate aerosol geoengineering detectability to the choice of filter. With the same trend-based filter but a non-stationary method, 80% of the comparisons would require fewer than 10 years for detection. This does not imply sulphate aerosol geoengineering should be deployed, but suggests that both detection methods could be used for monitoring geoengineering in global, annual mean temperature should it be needed.« less

  6. A Risk-Based Framework for Assessing the Effectiveness of Stratospheric Aerosol Geoengineering

    PubMed Central

    Ferraro, Angus J.; Charlton-Perez, Andrew J.; Highwood, Eleanor J.

    2014-01-01

    Geoengineering by stratospheric aerosol injection has been proposed as a policy response to warming from human emissions of greenhouse gases, but it may produce unequal regional impacts. We present a simple, intuitive risk-based framework for classifying these impacts according to whether geoengineering increases or decreases the risk of substantial climate change, with further classification by the level of existing risk from climate change from increasing carbon dioxide concentrations. This framework is applied to two climate model simulations of geoengineering counterbalancing the surface warming produced by a quadrupling of carbon dioxide concentrations, with one using a layer of sulphate aerosol in the lower stratosphere, and the other a reduction in total solar irradiance. The solar dimming model simulation shows less regional inequality of impacts compared with the aerosol geoengineering simulation. In the solar dimming simulation, 10% of the Earth's surface area, containing 10% of its population and 11% of its gross domestic product, experiences greater risk of substantial precipitation changes under geoengineering than under enhanced carbon dioxide concentrations. In the aerosol geoengineering simulation the increased risk of substantial precipitation change is experienced by 42% of Earth's surface area, containing 36% of its population and 60% of its gross domestic product. PMID:24533155

  7. The Many Problems with Geoengineering Using Stratospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Robock, Alan

    2009-05-01

    In response to the global warming problem, there has been a recent renewed call for geoengineering ``solutions'' involving injecting particles into the stratosphere or blocking sunlight with satellites between the Sun and Earth. While volcanic eruptions have been suggested as innocuous examples of stratospheric aerosols cooling the planet, the volcano analog actually argues against geoengineering because of ozone depletion and regional hydrologic and temperature responses. In this talk, I consider the suggestion to create an artificial stratospheric aerosol layer. No systems to conduct geoengineering now exist, but a comparison of different proposed stratospheric injection schemes, airplanes, balloons, artillery, and a space elevator, shows that using airplanes would not be that expensive. We simulated the climate response to both tropical and Arctic stratospheric injection of sulfate aerosol precursors using a comprehensive atmosphere-ocean general circulation model, the National Aeronautics and Space Administration Goddard Institute for Space Studies ModelE. We simulated the injection of SO2 and the model converts it to sulfate aerosols, transports them and removes them through dry and wet deposition, and calculates the climate response to the radiative forcing from the aerosols. We conducted simulations of future climate with the Intergovernmental Panel on Climate Change A1B business-as-usual scenario both with and without geoengineering, and compare the results. We found that if there were a way to continuously inject SO2 into the lower stratosphere, it would produce global cooling. Acid deposition from the sulfate would not be enough to disturb most ecosystems. Tropical SO2 injection would produce sustained cooling over most of the world, with more cooling over continents. Arctic SO2 injection would not just cool the Arctic. But both tropical and Arctic SO2 injection would disrupt the Asian and African summer monsoons, reducing precipitation to the food supply

  8. An overview of geoengineering of climate using stratospheric sulphate aerosols

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rasch, Philip J.; Tilmes, S.; Turco, Richard P.

    2010-01-01

    We provide an overview of geoengineering by stratospheric sulphate aerosols. The state of understanding about this topic as of early 2008 is reviewed, summarizing the past 30 years of work in the area, highlighting some very recent studies using climate models, and discussing methods used to deliver sulphur species to the stratosphere. The studies reviewed here suggest that sulphate aerosols can counteract the globally averaged temperature increase associated with increasing greenhouse gases, and reduce changes to some other components of the Earth system. There are likely to be remaining regional climate changes after geoengineering, with some regions experiencing significant changesmore » in temperature or precipitation. The aerosols also serve as surfaces for heterogeneous chemistry resulting in increased ozone depletion. The delivery of sulphur species to the stratosphere in a way that will produce particles of the right size is shown to be a complex and potentially very difficult task. Two simple delivery scenarios are explored, but similar exercises will be needed for other suggested delivery mechanisms. While the introduction of the geoengineering source of sulphate aerosol will perturb the sulphur cycle of the stratosphere signicantly, it is a small perturbation to the total (stratosphere and troposphere) sulphur cycle. The geoengineering source would thus be a small contributor to the total global source of ‘acid rain’ that could be compensated for through improved pollution control of anthropogenic tropospheric sources. Some areas of research remain unexplored. Although ozone may be depleted, with a consequent increase to solar ultraviolet-B (UVB) energy reaching the surface and a potential impact on health and biological populations, the aerosols will also scatter and attenuate this part of the energy spectrum, and this may compensate the UVB enhancement associated with ozone depletion. The aerosol will also change the ratio of diffuse to direct

  9. An overview of geoengineering of climate using stratospheric sulphate aerosols.

    PubMed

    Rasch, Philip J; Tilmes, Simone; Turco, Richard P; Robock, Alan; Oman, Luke; Chen, Chih-Chieh; Stenchikov, Georgiy L; Garcia, Rolando R

    2008-11-13

    We provide an overview of geoengineering by stratospheric sulphate aerosols. The state of understanding about this topic as of early 2008 is reviewed, summarizing the past 30 years of work in the area, highlighting some very recent studies using climate models, and discussing methods used to deliver sulphur species to the stratosphere. The studies reviewed here suggest that sulphate aerosols can counteract the globally averaged temperature increase associated with increasing greenhouse gases, and reduce changes to some other components of the Earth system. There are likely to be remaining regional climate changes after geoengineering, with some regions experiencing significant changes in temperature or precipitation. The aerosols also serve as surfaces for heterogeneous chemistry resulting in increased ozone depletion. The delivery of sulphur species to the stratosphere in a way that will produce particles of the right size is shown to be a complex and potentially very difficult task. Two simple delivery scenarios are explored, but similar exercises will be needed for other suggested delivery mechanisms. While the introduction of the geoengineering source of sulphate aerosol will perturb the sulphur cycle of the stratosphere signicantly, it is a small perturbation to the total (stratosphere and troposphere) sulphur cycle. The geoengineering source would thus be a small contributor to the total global source of 'acid rain' that could be compensated for through improved pollution control of anthropogenic tropospheric sources. Some areas of research remain unexplored. Although ozone may be depleted, with a consequent increase to solar ultraviolet-B (UVB) energy reaching the surface and a potential impact on health and biological populations, the aerosols will also scatter and attenuate this part of the energy spectrum, and this may compensate the UVB enhancement associated with ozone depletion. The aerosol will also change the ratio of diffuse to direct energy

  10. Impact of geoengineered aerosols on the troposphere and stratosphere

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tilmes, S.; Garcia, Rolando R.; Kinnison, Douglas E.

    2009-06-27

    A coupled chemistry climate model, the Whole Atmosphere Community Climate Model was used to perform a transient climate simulation to quantify the impact of geoengineered aerosols on atmospheric processes. In contrast to previous model studies, the impact on stratospheric chemistry, including heterogeneous chemistry in the polar regions, is considered in this simulation. In the geoengineering simulation, a constant stratospheric distribution of volcanic-sized, liquid sulfate aerosols is imposed in the period 2020–2050, corresponding to an injection of 2 Tg S/a. The aerosol cools the troposphere compared to a baseline simulation. Assuming an Intergovernmental Panel on Climate Change A1B emission scenario, globalmore » warming is delayed by about 40 years in the troposphere with respect to the baseline scenario. Large local changes of precipitation and temperatures may occur as a result of geoengineering. Comparison with simulations carried out with the Community Atmosphere Model indicates the importance of stratospheric processes for estimating the impact of stratospheric aerosols on the Earth’s climate. Changes in stratospheric dynamics and chemistry, especially faster heterogeneous reactions, reduce the recovery of the ozone layer in middle and high latitudes for the Southern Hemisphere. In the geoengineering case, the recovery of the Antarctic ozone hole is delayed by about 30 years on the basis of this model simulation. For the Northern Hemisphere, a onefold to twofold increase of the chemical ozone depletion occurs owing to a simulated stronger polar vortex and colder temperatures compared to the baseline simulation, in agreement with observational estimates.« less

  11. An overview of the Earth system science of solar geoengineering: Overview of the earth system science of solar geoengineering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Irvine, Peter J.; Kravitz, Ben; Lawrence, Mark G.

    Solar geoengineering has been proposed as a means to cool the planet by increasing the reflection of sunlight back to space, for example by injecting reflective aerosol particles into the middle atmosphere. Such proposals are not able to physically substitute for mitigation of greenhouse gas emissions as a response to the risks of climate change, but might eventually be applied as a complementary approach to reduce climate risks. Thus, the Earth system consequences of solar geoengineering are central to understanding its potentials and risks. Here we review the state-of-the-art knowledge about geoengineering by stratospheric sulphate aerosol injection. We examine themore » common responses found in studies of an idealized form of solar geoengineering, in which the intensity of incoming sunlight is directly reduced in models. The studies reviewed are consistent in suggesting that solar geoengineering would generally reduce the differences in climate in comparison to future scenarios with elevated greenhouse gas concentrations and no solar geoengineering. However, it is clear that a solar geoengineered climate would be novel in some respects, for example a notable reduction in the intensity of the hydrological cycle. We provide an overview of the unique aspects of the response to stratospheric aerosol injection and the uncertainties around its consequences. We also consider the issues raised by the partial control over the climate that solar geoengineering would allow. Finally, this overview also highlights the key research gaps that will need to be resolved in order to effectively guide future decisions on the potential use of solar geoengineering.« less

  12. Stratospheric solar geoengineering without ozone loss.

    PubMed

    Keith, David W; Weisenstein, Debra K; Dykema, John A; Keutsch, Frank N

    2016-12-27

    Injecting sulfate aerosol into the stratosphere, the most frequently analyzed proposal for solar geoengineering, may reduce some climate risks, but it would also entail new risks, including ozone loss and heating of the lower tropical stratosphere, which, in turn, would increase water vapor concentration causing additional ozone loss and surface warming. We propose a method for stratospheric aerosol climate modification that uses a solid aerosol composed of alkaline metal salts that will convert hydrogen halides and nitric and sulfuric acids into stable salts to enable stratospheric geoengineering while reducing or reversing ozone depletion. Rather than minimizing reactive effects by reducing surface area using high refractive index materials, this method tailors the chemical reactivity. Specifically, we calculate that injection of calcite (CaCO 3 ) aerosol particles might reduce net radiative forcing while simultaneously increasing column ozone toward its preanthropogenic baseline. A radiative forcing of -1 W⋅m -2 , for example, might be achieved with a simultaneous 3.8% increase in column ozone using 2.1 Tg⋅y -1 of 275-nm radius calcite aerosol. Moreover, the radiative heating of the lower stratosphere would be roughly 10-fold less than if that same radiative forcing had been produced using sulfate aerosol. Although solar geoengineering cannot substitute for emissions cuts, it may supplement them by reducing some of the risks of climate change. Further research on this and similar methods could lead to reductions in risks and improved efficacy of solar geoengineering methods.

  13. Geoengineering with stratospheric aerosols: What do we not know after a decade of research?: GEOENGINEERING: WHAT DO WE NOT KNOW?

    DOE PAGES

    MacMartin, Douglas G.; Kravitz, Ben; Long, Jane C. S.; ...

    2016-11-17

    Any well-informed future decision on whether and how to deploy solar geoengineering requires balancing the impacts (both intended and unintended) of intervening in the climate against the impacts of not doing so. In spite of the tremendous progress in the last decade, the current state of knowledge remains insufficient to support an assessment of this balance, even for stratospheric aerosol geoengineering (SAG), arguably the best understood (practical) geoengineering method. We then articulate key unknowns associated with SAG, including both climate-science and design questions, as an essential step toward developing a future strategic research program that could address outstanding uncertainties.

  14. Effect of Sulfate Aerosol Geoengineering on Tropical cyclones

    NASA Astrophysics Data System (ADS)

    Wang, Q.; Moore, J.; Ji, D.

    2017-12-01

    Variation in tropical cyclone (TC) number and intensity is driven in part by changes in the thermodynamics that can be defined by ocean and atmospheric variables. Genesis Potential Index (GPI) and ventilation index (VI) are combinations of potential intensity, vertical wind shear, relative humidity, midlevel entropy deficit, and absolute vorticity that quantify thermodynamic forcing of TC activity under changed climates, and can be calculated from climate model output. Here we use five CMIP5 models running the RCP45 experiment the Geoengineering Model Intercomparison Project (GeoMIP) stratospheric aerosol injection G4 experiment to calculate the two indices over the 2020 to 2069 period. Globally, GPI under G4 is lower than under RCP45, though both have a slight increasing trend. Spatial patterns in the relative effectiveness of geoengineering show reductions in TC in all models in the North Atlantic basin, and northern Indian Ocean in all except NorESM1-M. In the North Pacific, most models also show relative reductions under G4. VI generally coincide with the GPI patterns. Most models project Potential intensity and Relative Humidity to be the dominant variable to affect genesis potential. Changes in vertical wind shear and vorticity are small with scatter across different models and ocean basins. We find that tropopause temperature maybe as important as sea surface temperature in effecting TC genesis. Thus stratospheric aerosol geoengineering impacts on potential intensity and hence TC intensity are reasonably consistent, but probably underestimated by statistical forecasts of Tropical North Atlantic hurricane activity driven by sea surface temperatures alone. However the impacts of geoengineering on other ocean basins are more difficult to assess, and require more complete understanding of their driving parameters under present day climates. Furthermore, the possible effects of stratospheric injection on chemical reactions in the stratosphere, such as ozone, are

  15. Sensitivity of Stratospheric Geoengineering with Black Carbon to Aerosol Size and Altitude of Injection

    NASA Technical Reports Server (NTRS)

    Kravitz, Ben; Robock, Alan; Shindell, Drew T.; Miller, Mark A.

    2012-01-01

    Simulations of stratospheric geoengineering with black carbon (BC) aerosols using a general circulation model with fixed sea surface temperatures show that the climate effects strongly depend on aerosol size and altitude of injection. 1 Tg BC/a injected into the lower stratosphere would cause little surface cooling for large radii but a large amount of surface cooling for small radii and stratospheric warming of over 60 C. With the exception of small particles, increasing the altitude of injection increases surface cooling and stratospheric warming. Stratospheric warming causes global ozone loss by up to 50% in the small radius case. The Antarctic shows less ozone loss due to reduction of polar stratospheric clouds, but strong circumpolar winds would enhance the Arctic ozone hole. Using diesel fuel to produce the aerosols is likely prohibitively expensive and infeasible. Although studying an absorbing aerosol is a useful counterpart to previous studies involving sulfate aerosols, black carbon geoengineering likely carries too many risks to make it a viable option for deployment.

  16. Atlantic hurricane response to geoengineering

    NASA Astrophysics Data System (ADS)

    Moore, John; Grinsted, Aslak; Ji, Duoying; Yu, Xiaoyong; Guo, Xiaoran

    2015-04-01

    Devastating Atlantic hurricanes are relatively rare events. However their intensity and frequency in a warming world may rapidly increase - perhaps by a factor of 5 for a 2°C mean global warming. Geoengineering by sulphate aerosol injection preferentially cools the tropics relative to the polar regions, including the hurricane main development region in the Atlantic, suggesting that geoengineering may be an effective method of controlling hurricanes. We examine this hypothesis using 6 Earth System Model simulations of climate under the GeoMIP G3 and G4 schemes that use aerosols to reduce the radiative forcing under the RCP4.5 scenario. We find that although temperatures are ameliorated by geoengineering, the numbers of storm surge events as big as that caused the 2005 Katrina hurricane are only slightly reduced compared with no geoengineering. As higher levels of sulphate aerosol injection produce diminishing returns in terms of cooling, but cause undesirable effects in various regions, it seems that stratospheric aerosol geoengineering is not an effective method of controlling hurricane damage.

  17. Glacier evolution in high-mountain Asia under stratospheric sulfate aerosol injection geoengineering

    NASA Astrophysics Data System (ADS)

    Zhao, Liyun; Yang, Yi; Cheng, Wei; Ji, Duoying; Moore, John C.

    2017-06-01

    Geoengineering by stratospheric sulfate aerosol injection may help preserve mountain glaciers by reducing summer temperatures. We examine this hypothesis for the glaciers in high-mountain Asia using a glacier mass balance model driven by climate simulations from the Geoengineering Model Intercomparison Project (GeoMIP). The G3 and G4 schemes specify use of stratospheric sulfate aerosols to reduce the radiative forcing under the Representative Concentration Pathway (RCP) 4.5 scenario for the 50 years between 2020 and 2069, and for a further 20 years after termination of geoengineering. We estimate and compare glacier volume loss for every glacier in the region using a glacier model based on surface mass balance parameterization under climate projections from three Earth system models under G3, five models under G4, and six models under RCP4.5 and RCP8.5. The ensemble projections suggest that glacier shrinkage over the period 2010-2069 is equivalent to sea-level rise of 9.0 ± 1.6 mm (G3), 9.8 ± 4.3 mm (G4), 15.5 ± 2.3 mm (RCP4.5), and 18.5 ± 1.7 mm (RCP8.5). Although G3 keeps the average temperature from increasing in the geoengineering period, G3 only slows glacier shrinkage by about 50 % relative to losses from RCP8.5. Approximately 72 % of glaciated area remains at 2069 under G3, as compared with about 30 % for RCP8.5. The widely reported reduction in mean precipitation expected for solar geoengineering is unlikely to be as important as the temperature-driven shift from solid to liquid precipitation for forcing Himalayan glacier change. The termination of geoengineering at 2069 under G3 leads to temperature rise of about 1.3 °C over the period 2070-2089 relative to the period 2050-2069 and corresponding increase in annual mean glacier volume loss rate from 0.17 to 1.1 % yr-1, which is higher than the 0.66 % yr-1 under RCP8.5 during 2070-2089.

  18. Comparative climate response of using three different aerosol geoengineering techniques to transfer from RCP8.5 to RCP4.5

    NASA Astrophysics Data System (ADS)

    Muri, Helene; Tjiputra, Jerry; Grini, Alf; Helge Otterå, Odd; Lauvset, Siv K.; Schulz, Michael; Egill Kristjánsson, Jón

    2017-04-01

    Considering the ambitious climate targets of the Paris Agreement to limit global warming to 2°C, with aspirations of even 1.5°C, questions regarding how to achieve this arise. Geoengineering has been proposed as potential tool in such efforts to minimise global harm from anthropogenic climate change. An Earth system model is here used to evaluate the feasibility of transferring from the high CO2 concentrations scenario RCP8.5 to a middle-of-road scenario, RCP4.5, using geoengineering. Three different atmospheric aerosol - based geoengineering techniques are considered: stratospheric aerosol injections (SAI), marine sky brightening (MSB) and cirrus cloud thinning (CCT). We furthermore assess the climate response to these three methods. The climate of the geoengineered cases are for the most much closer to that of RCP4.5 than RCP8.5 and many anthropogenic global warming symptoms are alleviated. All three techniques result in comparatively the same global temperature evolution. Though there are some notable differences in other climate variables due to the nature of the forcings applied. CCT acts mainly on the longwave part of the radiation budget, as opposed to MSB and SAI acting in the shortwave, yielding a difference in the response, particularly for the hydrological cycle. Finally, the effects of a sudden cessation of large-scale aerosol geoengineering deployment is explored. The climate very rapidly, within few years, reverts back to the path of RCP8.5 post-termination, urging the need for simultaneous mitigation and possibly carbon removal from the atmosphere, even if one would dare to enter into any such form of geoengineering.

  19. The risks and efficacy of solar geoengineering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Keith, David

    2012-12-05

    Solar geoengineering may enable a significant reduction in climate risks by partially offsetting climate change due to increasing greenhouse gases, however this emerging technology entails novel risks and uncertainties along with serious challenges to global governance. I will attempt a rough summary of the physics of solar geoengineering and present recent findings regarding (a) the climate's response to radiative forcing by stratospheric aerosols, (b) methods of producing appropriate aerosol distributions, and (c) risks. In closing I will discuss the trade-off between solar geoengineering, emissions reductions and adaptation in climate policy.

  20. Geo-Engineering Climate Change with Sulfate Aerosol

    NASA Astrophysics Data System (ADS)

    Rasch, P. J.; Crutzen, P. J.

    2006-12-01

    We explore the impact of injecting a precursor of sulfate aerosols into the middle atmosphere where they would act to increase the planetary albedo and thus counter some of the effects of greenhouse gase forcing. We use an atmospheric general circulation model (CAM, the Community Atmosphere Model) coupled to a slab ocean model for this study. Only physical effects are examined, that is we ignore the biogeochemical and chemical implications of changes to greenhouse gases and aerosols, and do not explore the important ethical, legal, and moral issues that are associated with deliberate geo-engineering efforts. The simulations suggest that the sulfate aerosol produced from the SO2 source in the stratosphere is sufficient to counterbalance most of the warming associated with the greenhouse gas forcing. Surface temperatures return to within a few tenths of a degree(K) of present day levels. Sea ice and precipitation distributions are also much closer to their present day values. The polar region surface temperatures remain 1-3 degrees warm in the winter hemisphere than present day values. This study is very preliminary. Only a subset of the relevant effects have been explored. The effect of such an injection of aerosols on middle atmospheric chemistry, and the effect on cirrus clouds are obvious missing components that merit scrutiny. There are probably others that should be considered. The injection of such aerosols cannot help in ameliorating the effects of CO2 changes on ocean PH, or other effects on the biogeochemistry of the earth system.

  1. SPICE Work Package 3: Modelling the Effects of Stratospheric Aerosol Geoengineering

    NASA Astrophysics Data System (ADS)

    Driscoll, Simon

    2015-04-01

    This talk presents the results of the SPICE Work Package 3. There is an obvious need for methods to verify the accuracy of geoengineering given no observations of a geoengineering programme. Accordingly, model ability in reproducing the observed dynamical response to volcanic eruptions is discussed using analysis of CMIP5 data and different configurations of the HadGEM2 model. With the HadGEM2-L60 model shown to be substantially better in reproducing the observed dynamical response to volcanic eruptions, simulations of GeoMIP's G4 scenario are performed. Simulated impacts of geoengineering are described, and asymmetries between the immediate onset and immediate cessation ('termination') of geoengineering are analysed. Whilst a rapid large increase in stratospheric sulphate aerosols (such as from volcanic eruptions) can cause substantial damage, most volcanic eruptions in general are not catastrophic. One may therefore suspect that an 'equal but opposite' change in radiative forcing from termination may therefore not be catastrophic, if the climatic response is simulated to be symmetric. HadGEM2 simulations reveal a substantially more rapid change in variables such as near-surface temperature and precipitation following termination than the onset, indicating that termination may be substantially more damaging and even catastrophic. Some suggestions for hemispherically asymmetric geoengineering have been proposed as a way to reduce Northern Hemisphere sea ice, for example, with lesser impacts on the rest of the climate. However, HadGEM2 simulations are performed and observations analysed following volcanic eruptions. Both indicate substantial averse consequences from hemispherically asymmetric loading of stratospheric loading on precipitation in the Sahelian region - a vulnerable region where drought has caused hundreds of thousands of deaths and created millions of refugees in the past.

  2. Future Directions in Simulating Solar Geoengineering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kravitz, Benjamin S.; Robock, Alan; Boucher, Olivier

    2014-08-05

    Solar geoengineering is a proposed set of technologies to temporarily alleviate some of the consequences of anthropogenic greenhouse gas emissions. The Geoengineering Model Intercomparison Project (GeoMIP) created a framework of geoengineering simulations in climate models that have been performed by modeling centers throughout the world (B. Kravitz et al., The Geoengineering Model Intercomparison Project (GeoMIP), Atmospheric Science Letters, 12(2), 162-167, doi:10.1002/asl.316, 2011). These experiments use state-of-the-art climate models to simulate solar geoengineering via uniform solar reduction, creation of stratospheric sulfate aerosol layers, or injecting sea spray into the marine boundary layer. GeoMIP has been quite successful in its mission ofmore » revealing robust features and key uncertainties of the modeled effects of solar geoengineering.« less

  3. First Simulations of Designing Stratospheric Sulfate Aerosol Geoengineering to Meet Multiple Simultaneous Climate Objectives: DESIGNING STRATOSPHERIC GEOENGINEERING

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kravitz, Ben; MacMartin, Douglas G.; Mills, Michael J.

    We describe the first simulations of stratospheric sulfate aerosol geoengineering using multiple injection locations to meet multiple simultaneous surface temperature objectives. Simulations were performed using CESM1(WACCM), a coupled atmosphere-ocean general circulation model with fully interactive stratospheric chemistry, dynamics (including an internally generated quasi-biennial oscillation), and a sophisticated treatment of sulfate aerosol formation, microphysical growth, and deposition. The objectives are defined as maintaining three temperature features at their 2020 levels against a background of the RCP8.5 scenario over the period 2020-2099. These objectives are met using a feedback mechanism in which the rate of sulfur dioxide injection at each of themore » four locations is adjusted independently every year of simulation. Even in the presence of uncertainties, nonlinearities, and variability, the objectives are met, predominantly by SO2 injection at 30°N and 30°S. By the last year of simulation, the feedback algorithm calls for a total injection rate of 51 Tg SO2 per year. The injections are not in the tropics, which results in a greater degree of linearity of the surface climate response with injection amount than has been found in many previous studies using injection at the equator. Because the objectives are defined in terms of annual mean temperature, the required geeongineering results in "overcooling" during summer and "undercooling" during winter. The hydrological cycle is also suppressed as compared to the reference values corresponding to the year 2020. The demonstration we describe in this study is an important step toward understanding what geoengineering can do and what it cannot do.« less

  4. The Impact of Geoengineering Aerosols on Stratospheric Temperature and Ozone

    NASA Technical Reports Server (NTRS)

    Heckendorn, P.; Weisenstein, D.; Fueglistaler, S.; Luo, B. P.; Rozanov, E.; Schraner, M.; Peter, T.; Thomason, L. W.

    2009-01-01

    Anthropogenic greenhouse gas emissions are warming the global climate at an unprecedented rate. Significant emission reductions will be required soon to avoid a rapid temperature rise. As a potential interim measure to avoid extreme temperature increase, it has been suggested that Earth's albedo be increased by artificially enhancing stratospheric sulfate aerosols. We use a 3D chemistry climate model, fed by aerosol size distributions from a zonal mean aerosol model, to simulate continuous injection of 1-10 Mt/a into the lower tropical stratosphere. In contrast to the case for all previous work, the particles are predicted to grow to larger sizes than are observed after volcanic eruptions. The reason is the continuous supply of sulfuric acid and hence freshly formed small aerosol particles, which enhance the formation of large aerosol particles by coagulation and, to a lesser extent, by condensation. Owing to their large size, these particles have a reduced albedo. Furthermore, their sedimentation results in a non-linear relationship between stratospheric aerosol burden and annual injection, leading to a reduction of the targeted cooling. More importantly, the sedimenting particles heat the tropical cold point tropopause and, hence, the stratospheric entry mixing ratio of H2O increases. Therefore, geoengineering by means of sulfate aerosols is predicted to accelerate the hydroxyl catalyzed ozone destruction cycles and cause a significant depletion of the ozone layer even though future halogen concentrations will be significantly reduced.

  5. The Impact of Geoengineering Aerosols on Stratospheric Temperature and Ozone

    NASA Technical Reports Server (NTRS)

    Heckendorn, P.; Weisenstein, D.; Fueglistaler, S.; Luo, B. P.; Rozanov, E.; Schraner, M.; Thomason, L. W.; Peter, T.

    2011-01-01

    Anthropogenic greenhouse gas emissions are warming the global climate at an unprecedented rate. Significant emission reductions will be required soon to avoid a rapid temperature rise. As a potential interim measure to avoid extreme temperature increase, it has been suggested that Earth's albedo be increased by artificially enhancing stratospheric sulfate aerosols. We use a 3D chemistry climate model, fed by aerosol size distributions from a zonal mean aerosol model. to simulate continuous injection of 1-10 Mt/a into the lower tropical stratosphere. In contrast to the case for all previous work, the particles are predicted to grow to larger sizes than are observed after volcanic eruptions. The reason is the continuous supply of sulfuric acid and hence freshly formed small aerosol particles, which enhance the formation of large aerosol particles by coagulation and, to a lesser extent, by condensation. Owing to their large size, these particles have a reduced albedo. Furthermore, their sedimentation results in a non-linear relationship between stratospheric aerosol burden and annual injection, leading to a reduction of the targeted cooling. More importantly, the sedimenting particles heat the tropical cold point tropopause and, hence, the stratospheric entry mixing ratio of H2O increases. Therefore, geoengineering by means of sulfate aerosols is predicted to accelerate the hydroxyl catalyzed ozone destruction cycles and cause a significant depletion of the ozone layer even though future halogen concentrations will he significantly reduced.

  6. Detecting the global and regional effects of sulphate aerosol geoengineering

    NASA Astrophysics Data System (ADS)

    Lo, Eunice; Charlton-Perez, Andrew; Highwood, Ellie

    2017-04-01

    Climate warming is unequivocal. In addition to carbon dioxide emission mitigation, some geoengineering ideas have been proposed to reduce future surface temperature rise. One of these proposals involves injecting sulphate aerosols into the stratosphere to increase the planet's albedo. Monitoring the effectiveness of sulphate aerosol injection (SAI) would require us to be able to distinguish and detect its cooling effect from the climate system's internal variability and other externally forced temperature changes. This research uses optimal fingerprinting techniques together with simulations from the GeoMIP data base to estimate the number of years of observations that would be needed to detect SAI's cooling signal in near-surface air temperature, should 5 Tg of sulphur dioxide be injected into the stratosphere per year on top of RCP4.5 from 2020-2070. The first part of the research compares the application of two detection methods that have different null hypotheses to SAI detection in global mean near-surface temperature. The first method assumes climate noise to be dominated by unforced climate variability and attempts to detect the SAI cooling signal and greenhouse gas driven warming signal in the "observations" simultaneously against this noise. The second method considers greenhouse gas driven warming to be a non-stationary background climate and attempts to detect the net cooling effect of SAI against this background. Results from this part of the research show that the conventional multi-variate detection method that has been extensively used to attribute climate warming to anthropogenic sources could also be applied for geoengineering detection. The second part of the research investigates detection of geoengineering effects on the regional scale. The globe is divided into various sub-continental scale regions and the cooling effect of SAI is looked for in the temperature time series in each of these regions using total least squares multi

  7. Atlantic hurricane surge response to geoengineering

    PubMed Central

    Moore, John C.; Grinsted, Aslak; Guo, Xiaoran; Yu, Xiaoyong; Jevrejeva, Svetlana; Rinke, Annette; Cui, Xuefeng; Kravitz, Ben; Lenton, Andrew; Watanabe, Shingo; Ji, Duoying

    2015-01-01

    Devastating floods due to Atlantic hurricanes are relatively rare events. However, the frequency of the most intense storms is likely to increase with rises in sea surface temperatures. Geoengineering by stratospheric sulfate aerosol injection cools the tropics relative to the polar regions, including the hurricane Main Development Region in the Atlantic, suggesting that geoengineering may mitigate hurricanes. We examine this hypothesis using eight earth system model simulations of climate under the Geoengineering Model Intercomparison Project (GeoMIP) G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the Representative Concentration Pathway (RCP) 4.5 scenario. Global mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those temperature increases in the RCP4.5. However, sulfate injection would have to double (to nearly 10 teragrams of SO2 per year) between 2020 and 2070 to balance the RCP4.5, approximately the equivalent of a 1991 Pinatubo eruption every 2 y, with consequent implications for stratospheric ozone. We project changes in storm frequencies using a temperature-dependent generalized extreme value statistical model calibrated by historical storm surges and observed temperatures since 1923. The number of storm surge events as big as the one caused by the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this reduction is only marginally statistically significant. Nevertheless, when sea level rise differences in 2070 between the RCP4.5 and geoengineering are factored into coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5-y events and about halved for 50-y surges. PMID:26504210

  8. Atlantic hurricane surge response to geoengineering.

    PubMed

    Moore, John C; Grinsted, Aslak; Guo, Xiaoran; Yu, Xiaoyong; Jevrejeva, Svetlana; Rinke, Annette; Cui, Xuefeng; Kravitz, Ben; Lenton, Andrew; Watanabe, Shingo; Ji, Duoying

    2015-11-10

    Devastating floods due to Atlantic hurricanes are relatively rare events. However, the frequency of the most intense storms is likely to increase with rises in sea surface temperatures. Geoengineering by stratospheric sulfate aerosol injection cools the tropics relative to the polar regions, including the hurricane Main Development Region in the Atlantic, suggesting that geoengineering may mitigate hurricanes. We examine this hypothesis using eight earth system model simulations of climate under the Geoengineering Model Intercomparison Project (GeoMIP) G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the Representative Concentration Pathway (RCP) 4.5 scenario. Global mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those temperature increases in the RCP4.5. However, sulfate injection would have to double (to nearly 10 teragrams of SO2 per year) between 2020 and 2070 to balance the RCP4.5, approximately the equivalent of a 1991 Pinatubo eruption every 2 y, with consequent implications for stratospheric ozone. We project changes in storm frequencies using a temperature-dependent generalized extreme value statistical model calibrated by historical storm surges and observed temperatures since 1923. The number of storm surge events as big as the one caused by the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this reduction is only marginally statistically significant. Nevertheless, when sea level rise differences in 2070 between the RCP4.5 and geoengineering are factored into coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5-y events and about halved for 50-y surges.

  9. In Brief: Geoengineering draft statement

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2009-04-01

    The American Meteorological Society (AMS) has prepared a draft policy statement on geoengineering the climate system, which the AMS Council is considering for approval. The statement notes, “Geoengineering will not substitute for either aggressive mitigation or proactive adaptation. It could contribute to a comprehensive risk management strategy to slow climate change and alleviate its negative impacts, but the potential for adverse and unintended consequences implies a need for adequate research, appropriate regulation, and transparent consideration.” The statement, if adopted, indicates that AMS recommends enhanced research on the scientific and technological potential for geoengineering the climate system; additional study of the historical, ethical, legal, political, and societal aspects of the geoengineering issues; and the development and analysis of policy options to promote transparency and international cooperation in exploring geoengineering options along with restrictions on reckless efforts to manipulate the climate system. AMS is accepting comments on the draft statement until 23 April. For more information, visit http://ametsoc.org/policy/draftstatements/index.html#draft.

  10. Effects of Arctic geoengineering on precipitation in the tropical monsoon regions

    NASA Astrophysics Data System (ADS)

    Nalam, Aditya; Bala, Govindasamy; Modak, Angshuman

    2017-07-01

    Arctic geoengineering wherein sunlight absorption is reduced only in the Arctic has been suggested as a remedial measure to counteract the on-going rapid climate change in the Arctic. Several modeling studies have shown that Arctic geoengineering can minimize Arctic warming but will shift the Inter-tropical Convergence Zone (ITCZ) southward, unless offset by comparable geoengineering in the Southern Hemisphere. In this study, we investigate and quantify the implications of this ITCZ shift due to Arctic geoengineering for the global monsoon regions using the Community Atmosphere Model version 4 coupled to a slab ocean model. A doubling of CO2 from pre-industrial levels leads to a warming of 6 K in the Arctic region and precipitation in the monsoon regions increases by up to 15%. In our Arctic geoengineering simulation which illustrates a plausible latitudinal distribution of the reduction in sunlight, an addition of sulfate aerosols (11 Mt) in the Arctic stratosphere nearly offsets the Arctic warming due to CO2 doubling but this shifts the ITCZ southward by 1.5° relative to the pre-industrial climate. The combined effect from this shift and the residual CO2-induced climate change in the tropics is a decrease/increase in annual mean precipitation in the Northern Hemisphere/Southern Hemisphere monsoon regions by up to -12/+17%. Polar geoengineering where sulfate aerosols are prescribed in both the Arctic (10 Mt) and Antarctic (8 Mt) nearly offsets the ITCZ shift due to Arctic geoengineering, but there is still a residual precipitation increase (up to 7%) in most monsoon regions associated with the residual CO2 induced warming in the tropics. The ITCZ shift due to our Global geoengineering simulation, where aerosols (20 Mt) are prescribed uniformly around the globe, is much smaller and the precipitation changes in most monsoon regions are within ±2% as the residual CO2-induced warming in the tropics is also much less than in Arctic and Polar geoengineering. Further

  11. Arctic climate response to geoengineering with stratospheric sulfate aerosols

    NASA Astrophysics Data System (ADS)

    McCusker, K. E.; Battisti, D. S.; Bitz, C. M.

    2010-12-01

    Recent warming and record summer sea-ice area minimums have spurred expressions of concern for arctic ecosystems, permafrost, and polar bear populations, among other things. Geoengineering by stratospheric sulfate aerosol injections to deliberately cancel the anthropogenic temperature rise has been put forth as a possible solution to restoring Arctic (and global) climate to modern conditions. However, climate is particularly sensitive in the northern high latitudes, responding easily to radiative forcing changes. To that end, we explore the extent to which tropical injections of stratospheric sulfate aerosol can accomplish regional cancellation in the Arctic. We use the Community Climate System Model version 3 global climate model to execute simulations with combinations of doubled CO2 and imposed stratospheric sulfate burdens to investigate the effects on high latitude climate. We further explore the sensitivity of the polar climate to ocean dynamics by running a suite of simulations with and without ocean dynamics, transiently and to equilibrium respectively. We find that, although annual, global mean temperature cancellation is accomplished, there is over-cooling on land in Arctic summer, but residual warming in Arctic winter, which is largely due to atmospheric circulation changes. Furthermore, the spatial extent of these features and their concurrent impacts on sea-ice properties are modified by the inclusion of ocean dynamical feedbacks.

  12. Atlantic hurricane surge response to geoengineering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moore, John C.; Grinsted, Aslak; Guo, Xiaoran

    Devastating Atlantic hurricanes are relatively rare events. However their intensity and frequency in a warming world may rapidly increase by a factor of 2-7 for each degree of increase in mean global temperature. Geoengineering by stratospheric sulphate aerosol injection cools the tropics relative to the polar regions, including the hurricane main development region in the Atlantic, suggesting that geoengineering may be an effective method of controlling hurricanes. We examine this hypothesis using 8 Earth System Model simulations of climate under the GeoMIP G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the RCP4.5 scenario. Globalmore » mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those in RCP4.5, but sulphate injection would have to double between 2020 and 2070 to balance RCP 4.5 to nearly 10 Tg SO2 yr-1, with consequent implications for damage to stratospheric ozone. We project changes in storm frequencies using a temperature-dependent Generalized Extreme Value statistical model calibrated by historical storm surges from 1923 and observed temperatures. The numbers of storm surge events as big as the one that caused the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this is only marginally statistically significant. Furthermore, when sea level rise differences at 2070 between RCP4.5 and geoengineering are factored in to coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5 year events and perhaps halved for 50 year surges.« less

  13. Atlantic hurricane surge response to geoengineering

    DOE PAGES

    Moore, John C.; Grinsted, Aslak; Guo, Xiaoran; ...

    2015-10-26

    Devastating Atlantic hurricanes are relatively rare events. However their intensity and frequency in a warming world may rapidly increase by a factor of 2-7 for each degree of increase in mean global temperature. Geoengineering by stratospheric sulphate aerosol injection cools the tropics relative to the polar regions, including the hurricane main development region in the Atlantic, suggesting that geoengineering may be an effective method of controlling hurricanes. We examine this hypothesis using 8 Earth System Model simulations of climate under the GeoMIP G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the RCP4.5 scenario. Globalmore » mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those in RCP4.5, but sulphate injection would have to double between 2020 and 2070 to balance RCP 4.5 to nearly 10 Tg SO2 yr-1, with consequent implications for damage to stratospheric ozone. We project changes in storm frequencies using a temperature-dependent Generalized Extreme Value statistical model calibrated by historical storm surges from 1923 and observed temperatures. The numbers of storm surge events as big as the one that caused the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this is only marginally statistically significant. Furthermore, when sea level rise differences at 2070 between RCP4.5 and geoengineering are factored in to coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5 year events and perhaps halved for 50 year surges.« less

  14. Atlantic hurricane surge response to geoengineering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moore, John C.; Grinsted, Aslak; Guo, Xiaoran

    2015-10-26

    Devastating Atlantic hurricanes are relatively rare events. However their intensity and frequency in a warming world may rapidly increase by a factor of 2-7 for each degree of increase in mean global temperature. Geoengineering by stratospheric sulphate aerosol injection cools the tropics relative to the polar regions, including the hurricane main development region in the Atlantic, suggesting that geoengineering may be an effective method of controlling hurricanes. We examine this hypothesis using 8 Earth System Model simulations of climate under the GeoMIP G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the RCP4.5 scenario. Globalmore » mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those in RCP4.5, but sulphate injection would have to double between 2020 and 2070 to balance RCP 4.5 to nearly 10 Tg SO2 yr-1, with consequent implications for damage to stratospheric ozone. We project changes in storm frequencies using a temperature-dependent Generalized Extreme Value statistical model calibrated by historical storm surges from 1923 and observed temperatures. The numbers of storm surge events as big as the one that caused the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this is only marginally statistically significant. However, when sea level rise differences at 2070 between RCP4.5 and geoengineering are factored in to coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5 year events and perhaps halved for 50 year surges.« less

  15. We Don't Need a "Geoengineering" Research Program

    NASA Astrophysics Data System (ADS)

    Caldeira, K.

    2011-12-01

    Most approaches commonly labeled as 'geoengineering' can be divided into two categories: approaches that attempt to reduce the change in atmospheric composition caused by anthropogenic emissions (commonly labeled CDR, for Carbon Dioxide Removal), and approaches that attempt to reduce the change in climate caused by changes in atmospheric composition (commonly labeled SRM, for Sunlight Reflection Methods or Solar Radiation Management). CDR is relatively uncontroversial (apart from ocean fertilization), and the primary issues are typically cost, effectiveness, local environmental consequences, and verification. In contrast, SRM has provoked much controversy, because large-scale SRM deployments necessarily would affect everyone on this planet. Several proposals have been tabled for SRM-specific or geoengineering-specific research and governance structures, treating SRM or geoengineering research as a thing apart. We should instead view CDR and SRM research as part of a broader continuum of activities aimed at understanding Earth system dynamics and reducing risks associated with climate change. The scope of existing research efforts should be broadened so that CDR and SRM approaches are, at this stage in development, treated as an extension of what we are already doing. What is 'geoengineering research'? A primary need at this time is for expansion of scope of and funding for existing climate-related research efforts. For examples: Scientists studying the role of aerosols in clouds or stratospheric processes can expand the domain of concern to consider effects of intentionally introduced aerosols (and not just natural aerosols and aerosols we introduce as a byproduct of civilization's normal functioning). Scientists studying effects of land-surface change on global and regional climates can expand the domain of concern beyond inadvertent effects to consider effects of land-surface changes undertaken with the intent to affect these climates. Research programs aimed at

  16. Simultaneous stabilization of global temperature and precipitation through cocktail geoengineering

    NASA Astrophysics Data System (ADS)

    Cao, Long; Duan, Lei; Bala, Govindasamy; Caldeira, Ken

    2017-07-01

    Solar geoengineering has been proposed as a backup plan to offset some aspects of anthropogenic climate change if timely CO2 emission reductions fail to materialize. Modeling studies have shown that there are trade-offs between changes in temperature and hydrological cycle in response to solar geoengineering. Here we investigate the possibility of stabilizing both global mean temperature and precipitation simultaneously by combining two geoengineering approaches: stratospheric sulfate aerosol increase (SAI) that deflects sunlight to space and cirrus cloud thinning (CCT) that enables more longwave radiation to escape to space. Using the slab ocean configuration of National Center for Atmospheric Research Community Earth System Model, we simulate SAI by uniformly adding sulfate aerosol in the upper stratosphere and CCT by uniformly increasing cirrus cloud ice particle falling speed. Under an idealized warming scenario of abrupt quadrupling of atmospheric CO2, we show that by combining appropriate amounts of SAI and CCT geoengineering, global mean (or land mean) temperature and precipitation can be restored simultaneously to preindustrial levels. However, compared to SAI, cocktail geoengineering by mixing SAI and CCT does not markedly improve the overall similarity between geoengineered climate and preindustrial climate on regional scales. Some optimal spatially nonuniform mixture of SAI with CCT might have the potential to better mitigate climate change at both the global and regional scales.

  17. A new Geoengineering Model Intercomparison Project (GeoMIP) experiment designed for climate and chemistry models

    DOE PAGES

    Tilmes, S.; Mills, Mike; Niemeier, Ulrike; ...

    2015-01-15

    A new Geoengineering Model Intercomparison Project (GeoMIP) experiment "G4 specified stratospheric aerosols" (short name: G4SSA) is proposed to investigate the impact of stratospheric aerosol geoengineering on atmosphere, chemistry, dynamics, climate, and the environment. In contrast to the earlier G4 GeoMIP experiment, which requires an emission of sulfur dioxide (SO₂) into the model, a prescribed aerosol forcing file is provided to the community, to be consistently applied to future model experiments between 2020 and 2100. This stratospheric aerosol distribution, with a total burden of about 2 Tg S has been derived using the ECHAM5-HAM microphysical model, based on a continuous annualmore » tropical emission of 8 Tg SO₂ yr⁻¹. A ramp-up of geoengineering in 2020 and a ramp-down in 2070 over a period of 2 years are included in the distribution, while a background aerosol burden should be used for the last 3 decades of the experiment. The performance of this experiment using climate and chemistry models in a multi-model comparison framework will allow us to better understand the impact of geoengineering and its abrupt termination after 50 years in a changing environment. The zonal and monthly mean stratospheric aerosol input data set is available at https://www2.acd.ucar.edu/gcm/geomip-g4-specified-stratospheric-aerosol-data-set.« less

  18. Quantifying the risks of solid aerosol geoengineering: the role of fundamental material properties

    NASA Astrophysics Data System (ADS)

    Dykema, J. A.; Keutsch, F. N.; Keith, D.

    2017-12-01

    Solid aerosols have been considered as an alternative to sulfate aerosols for solar geoengineering due to their optical and chemical properties, which lead to different and possibly more attractive risk profiles. Solid aerosols can achieve higher solar scattering efficiency due to their higher refractive index, and in some cases may also be less effective absorbers of thermal infrared radiation. The optical properties of solid aerosols are however sensitive functions of the detailed physical properties of solid materials in question. The relevant details include the exact crystalline structure of the aerosols, the physical size of the particles, and interactions with background stratospheric molecular and particulate constituents. In this work, we examine the impact of these detailed physical properties on the radiative properties of calcite (CaCO3) solid aerosols. We examine how crystal morphology, size, chemical reactions, and interaction with background stratospheric aerosol may alter the scattering and absorption properties of calcite aerosols for solar and thermal infrared radiation. For example, in small particles, crystal lattice vibrations associated with the particle surface may lead to substantially different infrared absorption properties than bulk materials. We examine the wavelength dependence of absorption by the particles, which may lead to altered patterns of stratospheric radiative heating and equilibrium temperatures. Such temperature changes can lead to dynamical changes, with consequences for both stratospheric composition and tropospheric climate. We identify important uncertainties in the current state of understanding, investigate risks associated with these uncertainties, and survey potential approaches to quantitatively improving our knowledge of the relevant material properties.

  19. First Simulations of Designing Stratospheric Sulfate Aerosol Geoengineering to Meet Multiple Simultaneous Climate Objectives

    NASA Astrophysics Data System (ADS)

    Kravitz, Ben; MacMartin, Douglas G.; Mills, Michael J.; Richter, Jadwiga H.; Tilmes, Simone; Lamarque, Jean-Francois; Tribbia, Joseph J.; Vitt, Francis

    2017-12-01

    We describe the first simulations of stratospheric sulfate aerosol geoengineering using multiple injection locations to meet multiple simultaneous surface temperature objectives. Simulations were performed using CESM1(WACCM), a coupled atmosphere-ocean general circulation model with fully interactive stratospheric chemistry, dynamics (including an internally generated quasi-biennial oscillation), and a sophisticated treatment of sulfate aerosol formation, microphysical growth, and deposition. The objectives are defined as maintaining three temperature features at their 2020 levels against a background of the RCP8.5 scenario over the period 2020-2099. These objectives are met using a feedback mechanism in which the rate of sulfur dioxide injection at each of the four locations is adjusted independently every year of simulation. Even in the presence of uncertainties, nonlinearities, and variability, the objectives are met, predominantly by SO2 injection at 30°N and 30°S. By the last year of simulation, the feedback algorithm calls for a total injection rate of 51 Tg SO2 per year. The injections are not in the tropics, which results in a greater degree of linearity of the surface climate response with injection amount than has been found in many previous studies using injection at the equator. Because the objectives are defined in terms of annual mean temperature, the required geongineering results in "overcooling" during summer and "undercooling" during winter. The hydrological cycle is also suppressed as compared to the reference values corresponding to the year 2020. The demonstration we describe in this study is an important step toward understanding what geoengineering can do and what it cannot do.

  20. Modifications of the Quasi-biennial Oscillation by a Geoengineering Perturbation of the Stratospheric Aerosol Layer

    NASA Technical Reports Server (NTRS)

    Aquila, V.; Garfinkel, C. I.; Newman, P. A.; Oman, L. D.; Waugh, D. W.

    2014-01-01

    This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System (GEOS-5) Chemistry Climate Model. We performed four 30-year simulations with a continuous injection of sulfur dioxide on the equator at 0 degree longitude. The four simulations differ by the amount of sulfur dioxide injected (5Tg per year and 2.5 Tg per year) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. In the case of maximum perturbation, i.e. highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase. This locked QBO westerly phase is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere.

  1. Climate Curriculum Modules on Volcanic Eruptions, Geoengineering, and Nuclear Winter

    NASA Astrophysics Data System (ADS)

    Robock, A.

    2016-12-01

    To support a climate dynamics multidisciplinary curriculum for graduate and senior university students, I will describe proposed on-line modules on volcanic eruptions and climate, geoengineering, and nuclear winter. Each of these topics involves aerosols in the stratosphere and the response of the climate system, but each is distinct, and each is evolving as more research becomes available. While nature can load the stratosphere with sulfate aerosols for several years from large volcanic eruptions, humans could also put sulfate aerosols into the stratosphere on purpose through geoengineering or soot as a result of the fires from a nuclear war. As reported for the first time in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, volcanic eruptions are a natural analog for the climate impacts of potential anthropogenic aerosol injections into the stratosphere, either sulfates from potential attempts to cool the climate to counteract global warming, or smoke that would be produced from fires in cities and industrial targets in a nuclear war. Stratospheric aerosols would change the temperature, precipitation, total insolation, and fraction of diffuse radiation due to their radiative impacts, and could produce more ultraviolet radiation by ozone destruction. Surface ozone concentration could also change by changed transport from the stratosphere as well as changed tropospheric chemistry. There would be two options: 1) Each module would stand alone and could be taught independently, or 2) The volcanic eruptions module would stand alone, and would also serve as a prerequisite for each of the other two modules, which could be taught independently of each other. Each module includes consideration of the physical climate system as well as impacts of the resulting climate change. Geoengineering includes both solar radiation management and carbon dioxide reduction. The geoengineering and nuclear winter modules also include consideration of policy and

  2. Benefits, risks, and costs of stratospheric geoengineering

    NASA Astrophysics Data System (ADS)

    Robock, Alan; Marquardt, Allison; Kravitz, Ben; Stenchikov, Georgiy

    2009-10-01

    Injecting sulfate aerosol precursors into the stratosphere has been suggested as a means of geoengineering to cool the planet and reduce global warming. The decision to implement such a scheme would require a comparison of its benefits, dangers, and costs to those of other responses to global warming, including doing nothing. Here we evaluate those factors for stratospheric geoengineering with sulfate aerosols. Using existing U.S. military fighter and tanker planes, the annual costs of injecting aerosol precursors into the lower stratosphere would be several billion dollars. Using artillery or balloons to loft the gas would be much more expensive. We do not have enough information to evaluate more exotic techniques, such as pumping the gas up through a hose attached to a tower or balloon system. Anthropogenic stratospheric aerosol injection would cool the planet, stop the melting of sea ice and land-based glaciers, slow sea level rise, and increase the terrestrial carbon sink, but produce regional drought, ozone depletion, less sunlight for solar power, and make skies less blue. Furthermore it would hamper Earth-based optical astronomy, do nothing to stop ocean acidification, and present many ethical and moral issues. Further work is needed to quantify many of these factors to allow informed decision-making.

  3. The Climate Response to Stratospheric Aerosol Geoengineering Can Be Tailored Using Multiple Injection Locations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    MacMartin, Douglas G.; Kravitz, Ben; Tilmes, Simone

    The climate response to geoengineering with stratospheric aerosols has the potential to be designed to achieve some chosen objectives. By injecting different amounts of SO2 at multiple different latitudes, the spatial pattern of aerosol optical depth (AOD) can be partially controlled. We use simulations from the fully-coupled whole-atmosphere chemistry-climate model CESM1(WACCM), to demonstrate that three spatial degrees of freedom of AOD can be achieved by appropriately combining injection at different locations: an approximately spatially-uniform AOD distribution, the relative difference in AOD between Northern and Southern hemispheres, and the relative AOD in high versus low latitudes. For forcing levels that yieldmore » 1–2°C cooling, the AOD and surface temperature response are sufficiently linear in this model so that many climate effects can be predicted from single-latitude injection simulations. Optimized injection at multiple locations is predicted to improve compensation of CO2-forced climate change, relative to a case using only equatorial aerosol injection. The additional degrees of freedom can be used, for example, to balance interhemispheric temperature differences and the equator to pole temperature difference in addition to the global mean temperature; this is projected in this model to reduce the mean-square error in temperature compensation by 30%.« less

  4. Lifting options for stratospheric aerosol geoengineering: advantages of tethered balloon systems.

    PubMed

    Davidson, Peter; Burgoyne, Chris; Hunt, Hugh; Causier, Matt

    2012-09-13

    The Royal Society report 'Geoengineering the Climate' identified solar radiation management using albedo-enhancing aerosols injected into the stratosphere as the most affordable and effective option for geoengineering, but did not consider in any detail the options for delivery. This paper provides outline engineering analyses of the options, both for batch-delivery processes, following up on previous work for artillery shells, missiles, aircraft and free-flying balloons, as well as a more lengthy analysis of continuous-delivery systems that require a pipe connected to the ground and supported at a height of 20 km, either by a tower or by a tethered balloon. Towers are shown not to be practical, but a tethered balloon delivery system, with high-pressure pumping, appears to have much lower operating and capital costs than all other delivery options. Instead of transporting sulphuric acid mist precursors, such a system could also be used to transport slurries of high refractive index particles such as coated titanium dioxide. The use of such particles would allow useful experiments on opacity, coagulation and atmospheric chemistry at modest rates so as not to perturb regional or global climatic conditions, thus reducing scale-up risks. Criteria for particle choice are discussed, including the need to minimize or prevent ozone destruction. The paper estimates the time scales and relatively modest costs required if a tethered balloon system were to be introduced in a measured way with testing and development work proceeding over three decades, rather than in an emergency. The manufacture of a tether capable of sustaining the high tensions and internal pressures needed, as well as strong winds, is a significant challenge, as is the development of the necessary pumping and dispersion technologies. The greatest challenge may be the manufacture and launch of very large balloons, but means have been identified to significantly reduce the size of such balloons or aerostats.

  5. New AgMIP Scenarios: Impacts of Volcanic Eruptions, Geoengineering, or Nuclear War on Agriculture

    NASA Astrophysics Data System (ADS)

    Robock, A.; Xia, L.

    2016-12-01

    Climate is one of the most important factors determining crop yields and world food supplies. To be well prepared for possible futures, it is necessary to study yield changes of major crops in response to different climate forcings. Previous studies mainly focus on the impact from global warming. Here we propose that the AgMIP community also study the impacts of stratospheric aerosols on agriculture. While nature can load the stratosphere with sulfate aerosols for several years from large volcanic eruptions, humans could also put sulfate aerosols into the stratosphere on purpose through geoengineering or soot as a result of the fires from a nuclear war. Stratospheric aerosols would change the temperature, precipitation, total insolation, and fraction of diffuse radiation due to their radiative impacts, and could produce more ultraviolet radiation by ozone destruction. Surface ozone concentration could also change by changed transport from the stratosphere as well as changed tropospheric chemistry. As a demonstration of these effects, using the crop model in the NCAR Community Land Model (CLM-crop), we have studied sulfate injection geoengineering and nuclear war impacts on global agriculture in response to temperature, precipitation and radiation changes, and found significant changes in patterns of global food production. With the new ozone module in CLM-crop, we simulated how surface ozone concentration change under sulfate injection geoengineering would change the agriculture response. Agriculture would benefit from less surface ozone concentration associated with the specific geoengineering scenario comparing with the global warming scenario. Here, we would like to encourage more crop modelers to improve crop models in terms of crop responses to ozone, ultraviolet radiation, and diffuse radiation. We also invite more global crop modeling groups to use the climate forcing we would be happy to provide to gain a better understanding of global agriculture responses

  6. Impact of geoengineering on cirrus clouds

    NASA Astrophysics Data System (ADS)

    Cirisan, Ana; Spichtinger, Peter; Weisenstein, Debra; Lohmann, Ulrike; Wernli, Heini; Peter, Thomas

    2010-05-01

    Inspite of the framework convention agreement, climate warming is still an actual and very important issue society has to deal with. This has motivated some scientist to start thinking about implementation of artificial methods that could change the climate and weather patterns in order to stop or reverse the global warming effects. Nowadays, there is a consortium of politicians, scientists and engineers interested in evaluating different geoengineering schemes as a way to mitigate global warming, discount rates, and risk aversion (Polborn S. and Tintelnot F., 2009). The geoengineering proposal attracting the most attention and having considerably lower expected deployment costs than conventional emissions abatement approaches (Nordhaus, 2007) is stratospheric aerosol injection. This method, proposed by Budyko (1977) and Crutzen (2006), relies on the fact that large amounts of sulphur aerosols injected into the lower stratosphere enhance the Earth's albedo and lead to cooling of the globe. This proposal is currently discussed in the climate community and possible side effects are investigated. However, the investigations concentrate almost exclusively on the impact on chemistry and stratospheric circulation, whereas the impact on cirrus clouds in the underlying tropopause and upper troposphere region was not taken into account up to now. In this contribution we investigated the impact of artificially produced sulphate aerosol concentrations, modeled with the AER 2D aerosol model (Weisenstein et al., 2007), on the formation and evolution of cirrus clouds in the mid-latitudes. For large injections of SO2 some sulphate aerosol particles grow to large sizes that they can sediment to lower altitudes and eventually reach the troposphere, where they can influence ice crystal formation. Investigations are carried out using a bulk microphysical box model (Spichtinger and Gierens, 2009, Spichtinger and Cziczo, 2009), concentrating on moderate constant updrafts with different

  7. Solar Geoengineering and the Modulation of North Atlantic Tropical Cyclone Frequency

    NASA Astrophysics Data System (ADS)

    Jones, A. C.; Haywood, J. M.; Hawcroft, M.; Jones, A.; Dunstone, N. J.; Hodges, K.

    2017-12-01

    Solar geoengineering (SG) refers to a wide range of proposed methods for counteracting global warming by artificially reducing solar insolation at Earth's surface. The most widely known SG proposal is stratospheric aerosol injection (SAI) which has impacts analogous to those from large-scale volcanic eruptions. Observations following major volcanic eruptions indicate that aerosol enhancements confined to a single hemisphere effectively modulate North Atlantic tropical cyclone (TC) activity in the following years. Here we investigate the effects of both single-hemisphere and global SAI scenarios on North Atlantic TC activity using the HadGEM2-ES general circulation model (GCM). We show that a 5 Tg y-1 injection of sulphur dioxide (SO2) into the northern hemisphere (NH) stratosphere would produce a global-mean cooling of 1 K and simultaneously reduce TC activity (to 8 TCs y-1), while the same injection in the southern hemisphere (SH) would enhance TC activity (to 14 TCs y-1), relative to a recent historical period (1950-2000, 10 TCs y-1). Our results reemphasize the risks of regional geoengineering and should motivate policymakers to regulate large-scale unilateral geoengineering deployments.

  8. Stratospheric sulfate geoengineering could enhance the terrestrial photosynthesis rate

    DOE PAGES

    Xia, L.; Robock, A.; Tilmes, S.; ...

    2016-02-10

    Stratospheric sulfate geoengineering could impact the terrestrial carbon cycle by enhancing the carbon sink. With an 8 Tg yr -1 injection of SO 2 to produce a stratospheric aerosol cloud to balance anthropogenic radiative forcing from the Representative Concentration Pathway 6.0 (RCP6.0) scenario, we conducted climate model simulations with the Community Earth System Model – the Community Atmospheric Model 4 fully coupled to tropospheric and stratospheric chemistry (CAM4–chem). During the geoengineering period, as compared to RCP6.0, land-averaged downward visible (300–700 nm) diffuse radiation increased 3.2 W m -2 (11%). The enhanced diffuse radiation combined with the cooling increased plant photosynthesismore » by 0.07±0.02 µmol C m -2 s -1, which could contribute to an additional 3.8±1.1 Gt C yr -1 global gross primary productivity without explicit nutrient limitation. This increase could potentially increase the land carbon sink. Suppressed plant and soil respiration due to the cooling would reduce natural land carbon emission and therefore further enhance the terrestrial carbon sink during the geoengineering period. In conclusion, this potentially beneficial impact of stratospheric sulfate geoengineering would need to be balanced by a large number of potential risks in any future decisions about the implementation of geoengineering.« less

  9. Dangerous Climate Velocities from Geoengineering Termination: Potential Biodiversity Impacts

    NASA Astrophysics Data System (ADS)

    Trisos, C.; Gurevitch, J.; Zambri, B.; Xia, L.; Amatulli, G.; Robock, A.

    2016-12-01

    Geoengineering has been suggested as a potential societal response to the impacts of ongoing global warming. If ongoing mitigation and adaptation measures do not prevent the most dangerous consequences of climate change, it is important to study whether solar radiation management would make the world less dangerous. While impacts of albedo modification on temperature, precipitation, and agriculture have been studied before, here for the first time we investigate its potential ecological impacts. We estimate the speeds marine and terrestrial ecosystems will need to move to remain in their current climate conditions (i.e., climate velocities) in response to the implementation and subsequent termination of geoengineering. We take advantage of climate model simulations conducted using the G4 scenario of the Geoengineering Model Intercomparison Project, in which increased radiative forcing from the RCP4.5 scenario is balanced by a stratospheric aerosol cloud produced by an injection of 5 Tg of SO2 per year into the lower stratosphere for 50 years, and then stopped. The termination of geoengineering is projected to produce a very rapid warming of the climate, resulting in climate velocities much faster than those that will be produced from anthropogenic global warming. Should ongoing geoengineering be terminated abruptly due to society losing the means or will to continue, the resulting ecological impacts, as measured by climate velocities, could be severe for many terrestrial and marine biodiversity hotspots. Thus, the implementation of solar geoengineering represents a potential danger not just to humans, but also to biodiversity globally.

  10. The Climate Response to Stratospheric Aerosol Geoengineering Can Be Tailored Using Multiple Injection Locations

    NASA Astrophysics Data System (ADS)

    MacMartin, Douglas G.; Kravitz, Ben; Tilmes, Simone; Richter, Jadwiga H.; Mills, Michael J.; Lamarque, Jean-Francois; Tribbia, Joseph J.; Vitt, Francis

    2017-12-01

    By injecting different amounts of SO2 at multiple different latitudes, the spatial pattern of aerosol optical depth (AOD) can be partially controlled. This leads to the ability to influence the climate response to geoengineering with stratospheric aerosols, providing the potential for design. We use simulations from the fully coupled whole-atmosphere chemistry climate model CESM1(WACCM) to demonstrate that by appropriately combining injection at just four different locations, 30°S, 15°S, 15°N, and 30°N, then three spatial degrees of freedom of AOD can be achieved: an approximately spatially uniform AOD distribution, the relative difference in AOD between Northern and Southern Hemispheres, and the relative AOD in high versus low latitudes. For forcing levels that yield 1-2°C cooling, the AOD and surface temperature response are sufficiently linear in this model so that the response to different combinations of injection at different latitudes can be estimated from single-latitude injection simulations; nonlinearities associated with both aerosol growth and changes to stratospheric circulation will be increasingly important at higher forcing levels. Optimized injection at multiple locations is predicted to improve compensation of CO2-forced climate change relative to a case using only equatorial aerosol injection (which overcools the tropics relative to high latitudes). The additional degrees of freedom can be used, for example, to balance the interhemispheric temperature gradient and the equator to pole temperature gradient in addition to the global mean temperature. Further research is needed to better quantify the impacts of these strategies on changes to long-term temperature, precipitation, and other climate parameters.

  11. Geoengineering on exoplanets

    NASA Astrophysics Data System (ADS)

    Lockley, Andrew

    2015-04-01

    Solar radiation management (SRM) geoengineering can be used to deliberately alter the Earth's radiation budget, by reflecting sunlight to space. SRM has been suggested as a response to Anthropogenic Global Warming (AGW), to partly or fully balance radiative forcing from AGW [1]. Approximately 22% of sun-like stars have Earth-like exoplanets[2]. Advanced civilisations may exist on these, and may use geoengineering for positive or negative radiative forcing. Additionally, terraforming projects [e.g. 3], may be used to expand alien habitable territory, or for resource management or military operations on non-home planets. Potential observations of alien geoengineering and terraforming may enable detection of technologically advanced alien civilisations, and may help identify widely-used and stable geoengineering technologies. This knowledge may assist the development of safe and stable geoengineering methods for Earth. The potential risks and benefits of possible alien detection of Earth-bound geoengineering schemes must be considered before deployment of terrestrial geoengineering schemes.

  12. Stratospheric changes caused by geoengineering applications: potential repercussions and uncertainties

    NASA Astrophysics Data System (ADS)

    Kenzelmann, P.; Weisenstein, D.; Peter, T.; Luo, B. P.; Rozanov, E.; Fueglistaler, S.; Thomason, L. W.

    2009-04-01

    Anthropogenic greenhouse gas emissions tend to warm the global climate, calling for significant rapid emission reductions. As potential support measures various ideas for geoengineering are currently being discussed. The assessment of the possible manifold and as yet substantially unexplored repercussions of implementing geoengineering ideas to ameliorate climate change poses enormous challenges not least in the realm of aerosol-cloud-climate interactions. Sulphur aerosols cool the Earth's surface by reflecting short wave radiation. By increasing the amount of sulphur aerosols in the stratosphere, for example by sulphur dioxide injections, part of the anthropogenic climate warming might be compensated due to enhanced albedo. However, we are only at the beginning of understanding possible side effects. One such effect that such aerosol might have is the warming of the tropical tropopause and consequently the increase of the amount of stratospheric water vapour. Using the 2D AER Aerosol Model we calculated the aerosol distributions for yearly injections of 1, 2, 5 and 10 Mt sulphur into the lower tropical stratosphere. The results serve as input for the 3D chemistry-climate model SOCOL, which allows calculating the aerosol effect on stratospheric temperatures and chemistry. In the injection region the continuously formed sulphuric acid condensates rapidly on sulphate aerosol, which eventually grow to such extent that they sediment down to the tropical tropopause region. The growth of the aerosol particles depends on non-linear processes: the more sulphur is emitted the faster the particles grow. As a consequence for the scenario with continuous sulphur injection of totally 10 Mt per year, only 6 Mt sulphur are in the stratosphere if equilibrium is reached. According to our model calculations this amount of sulphate aerosols leads to a net surface forcing of -3.4 W/m2, which is less then expected radiative forcing by doubling of carbon dioxide concentration. Hence

  13. Climate Curriculum Modules on Volcanic Eruptions, Geoengineering, and Nuclear Winter

    NASA Astrophysics Data System (ADS)

    Robock, A.

    2014-12-01

    To support a climate dynamics multidisciplinary curriculum for graduate and senior university students, I will describe on-line modules on volcanic eruptions and climate, geoengineering, and nuclear winter. Each of these topics involves aerosols in the stratosphere and the response of the climate system, but each is distinct, and each is evolving as more research becomes available. As reported for the first time in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, volcanic eruptions are a natural analog for the climate impacts of potential anthropogenic aerosol injections into the stratosphere, either sulfates from potential attempts to cool the climate to counteract global warming, or smoke that would be produced from fires in cities and industrial targets in a nuclear war. The volcanic eruptions module would stand alone, and would also serve as a prerequisite for each of the other two modules, which could be taught independently of each other. Each module includes consideration of the physical climate system as well as impacts of the resulting climate change. Geoengineering includes both solar radiation management and carbon dioxide reduction. The geoengineering and nuclear winter modules also include consideration of policy and governance issues. Each module includes a slide set for use in lecturing, links to related resources, and student exercises. The modules will be regularly updated.

  14. Geoengineering to Avoid Overshoot: An Analysis of Uncertainty

    NASA Astrophysics Data System (ADS)

    Tanaka, Katsumasa; Cho, Cheolhung; Krey, Volker; Patt, Anthony; Rafaj, Peter; Rao-Skirbekk, Shilpa; Wagner, Fabian

    2010-05-01

    Even if a drastic 50% CO2-equivalent emissions reduction is achieved by year 2050, the chances of exceeding a 2°C warming are still substantial due to the uncertainty in the climate system (Meinshausen et al., 2009). Moreover, a strong mitigation is accompanied by overshoot, in which the global-mean temperature temporarily exceeds the target before arriving there. We are motivated by the question as to how much geoengineering would be considered if it were to be used to avoid overshoot even combined with a strong mitigation? How serious would the side effects be expected? This study focuses on stratospheric sulfur injections among other geoengineering proposals, the idea of which has been put forward by Crutzen (2006) and reviewed by Rasch et al. (2008). There are a number of concerns over geoengineering (e.g. Robock, 2008). But the concept of geoengineering requires further research (AMS, 2009). Studying geoengineering may be instructive to revisit the importance of mainstream mitigation strategies. The motivations above led to the following two closely linked studies: 1) Mitigation and Geoengineering The first study investigates the magnitude and start year of geoengineering intervention with the intent to avoid overshoot. This study explores the sensitivity of geoengineering profile to associated uncertainties in the climate system (climate sensitivity, tropospheric aerosol forcing, and ocean diffusivity) and in mitigation scenarios (target uncertainty (450ppm CO2-eq and 400ppm CO2-eq) and baseline uncertainty (A2, B1, and B2)). This study builds on Wigley's premise that demonstrated a basic potential of such a combined mitigation/geoengineering approach (Wigley, 2006) - however it did not examine the sensitivity of the climate response to any underlying uncertainties. This study uses a set of GGI low mitigation scenarios generated from the MESSAGE model (Riahi et al., 2007). The reduced-complexity climate and carbon cycle model ACC2 (Tanaka, 2008; Tanaka et al

  15. Upper tropospheric ice sensitivity to sulfate geoengineering

    NASA Astrophysics Data System (ADS)

    Visioni, Daniele; Pitari, Giovanni; Mancini, Eva

    2017-04-01

    In light of the Paris Agreement which aims to keep global warming under 2 °C in the next century and considering the emission scenarios produced by the IPCC for the same time span, it is likely that to remain below that threshold some kind of geoengineering technique will have to be deployed. Amongst the different methods, the injection of sulfur into the stratosphere has received much attention considering its effectiveness and affordability. Aside from the rather well established surface cooling sulfate geoengineering (SG) would produce, the investigation on possible side-effects of this method is still ongoing. For instance, some recent studies have investigated the effect SG would have on upper tropospheric cirrus clouds, expecially on the homogenous freezing mechanisms that produces the ice particles (Kuebbeler et al., 2012). The goal of the present study is to better understand the effect of thermal and dynamical anomalies caused by SG on the formation of ice crystals via homogeneous freezing by comparing a complete SG simulation with a RCP4.5 reference case and with a number of sensitivity studies where atmospheric temperature changes in the upper tropospheric region are specified in a schematic way as a function of the aerosol driven stratospheric warming and mid-lower tropospheric cooling. These changes in the temperature profile tend to increase atmospheric stabilization, thus decreasing updraft and with it the amount of water vapor available for homogeneous freezing in the upper troposphere. However, what still needs to be assessed is the interaction between this dynamical effect and the thermal effects of tropospheric cooling (which would increase ice nucleation rates) and stratospheric warming (which would probably extend to the uppermost troposphere via SG aerosol gravitational settling, thus reducing ice nucleation rates), in order to understand how they combine together. Changes in ice clouds coverage could be important for SG, because cirrus ice

  16. The radiative forcing potential of different climate geoengineering options

    NASA Astrophysics Data System (ADS)

    Lenton, T. M.; Vaughan, N. E.

    2009-01-01

    Climate geoengineering proposals seek to rectify the Earth's current radiative imbalance, either by reducing the absorption of incoming solar (shortwave) radiation, or by removing CO2 from the atmosphere and transferring it to long-lived reservoirs, thus increasing outgoing longwave radiation. A fundamental criterion for evaluating geoengineering options is their climate cooling effectiveness, which we quantify here in terms of radiative forcing potential. We use a simple analytical approach, based on the global energy balance and pulse response functions for the decay of CO2 perturbations. This aids transparency compared to calculations with complex numerical models, but is not intended to be definitive. Already it reveals some significant errors in existing calculations, and it allows us to compare the relative effectiveness of a range of proposals. By 2050, only stratospheric aerosol injections or sunshades in space have the potential to cool the climate back toward its pre-industrial state, but some land carbon cycle geoengineering options are of comparable magnitude to mitigation "wedges". Strong mitigation, i.e. large reductions in CO2 emissions, combined with global-scale air capture and storage, afforestation, and bio-char production, i.e. enhanced CO2 sinks, might be able to bring CO2 back to its pre-industrial level by 2100, thus removing the need for other geoengineering. Alternatively, strong mitigation stabilising CO2 at 500 ppm, combined with geoengineered increases in the albedo of marine stratiform clouds, grasslands, croplands and human settlements might achieve a patchy cancellation of radiative forcing. Ocean fertilisation options are only worthwhile if sustained on a millennial timescale and phosphorus addition probably has greater long-term potential than iron or nitrogen fertilisation. Enhancing ocean upwelling or downwelling have trivial effects on any meaningful timescale. Our approach provides a common framework for the evaluation of

  17. Sulfur deposition changes under sulfate geoengineering conditions: quasi-biennial oscillation effects on the transport and lifetime of stratospheric aerosols

    NASA Astrophysics Data System (ADS)

    Visioni, Daniele; Pitari, Giovanni; Tuccella, Paolo; Curci, Gabriele

    2018-02-01

    Sustained injection of sulfur dioxide (SO2) in the tropical lower stratosphere has been proposed as a climate engineering technique for the coming decades. Among several possible environmental side effects, the increase in sulfur deposition deserves additional investigation. In this study we present results from a composition-climate coupled model (University of L'Aquila Composition-Chemistry Model, ULAQ-CCM) and a chemistry-transport model (Goddard Earth Observing System Chemistry-Transport Model, GEOS-Chem), assuming a sustained lower-stratospheric equatorial injection of 8 Tg SO2 yr-1. Total S deposition is found to globally increase by 5.2 % when sulfate geoengineering is deployed, with a clear interhemispheric asymmetry (+3.8 and +10.3 % in the Northern Hemisphere (NH) and the Southern Hemisphere (SH), due to +2.2 and +1.8 Tg S yr-1, respectively). The two models show good consistency, both globally and on a regional scale under background and geoengineering conditions, except for S-deposition changes over Africa and the Arctic. The consistency exists with regard to time-averaged values but also with regard to monthly and interannual deposition changes. The latter is driven essentially by the variability in stratospheric large-scale transport associated with the quasi-biennial oscillation (QBO). Using an externally nudged QBO, it is shown how a zonal wind E shear favors aerosol confinement in the tropical pipe and a significant increase in their effective radius (+13 % with respect to W shear conditions). The net result is an increase in the downward cross-tropopause S flux over the tropics with dominant E shear conditions with respect to W shear periods (+0.61 Tg S yr-1, +42 %, mostly due to enhanced aerosol gravitational settling) and a decrease over the extratropics (-0.86 Tg S yr-1, -35 %, mostly due to decreased large-scale stratosphere-troposphere exchange of geoengineering sulfate). This translates into S-deposition changes that are significantly

  18. A geophysiologist's thoughts on geoengineering.

    PubMed

    Lovelock, James

    2008-11-13

    The Earth is now recognized as a self-regulating system that includes a reactive biosphere; the system maintains a long-term steady-state climate and surface chemical composition favourable for life. We are perturbing the steady state by changing the land surface from mainly forests to farm land and by adding greenhouse gases and aerosol pollutants to the air. We appear to have exceeded the natural capacity to counter our perturbation and consequently the system is changing to a new and as yet unknown but probably adverse state. I suggest here that we regard the Earth as a physiological system and consider amelioration techniques, geoengineering, as comparable to nineteenth century medicine.

  19. Geoengineering: A humanitarian concern

    NASA Astrophysics Data System (ADS)

    Suarez, Pablo; van Aalst, Maarten K.

    2017-02-01

    The humanitarian sector is active at the global frontline of climate impacts, and has a track record in influencing the climate change policy agenda. Geoengineering is a humanitarian concern: the potential for deliberate large-scale intervention in the Earth's climate system has major implications in terms of impacts on the most vulnerable. Yet, so far the humanitarian community has largely been absent from geoengineering deliberations. Geoengineering may be perceived as too theoretical, too complex, and not imminent enough to merit attention. However, early engagement by the sector is imperative to ensure that humanitarian considerations are integrated into policy decisions. Those who can suffer the worst outcomes need to be involved; especially given the plausibility of "predatory geoengineering" where recklessly self-concerned actions may result in harmful consequences to others. This paper explores the humanitarian dimensions of geoengineering, specifically relating to solar radiation management (SRM). Drawing from the engagement of the Red Cross Red Crescent Climate Centre in SRM discussions, we discuss how to improve linkages between science, policy and humanitarian practice. We further propose the creation of a geoengineering risk management framework to ensure that the interests of the most vulnerable are considered and addressed - including the voices of all stakeholders.

  20. Stratospheric Ozone Response in Experiments G3 and G4 of the Geoengineering Model Intercomparison Project (GeoMIP)

    NASA Technical Reports Server (NTRS)

    Pitari, Giovanni; Aquila, Valentina; Kravitz, Ben; Watanabe, Shingo; Tilmes, Simone; Mancini, Eva; DeLuca, Natalia; DiGenova, Glauco

    2013-01-01

    Geoengineering with stratospheric sulfate aerosols has been proposed as a means of temporarily cooling the planet, alleviating some of the side effects of anthropogenic CO2 emissions. However, one of the known side effects of stratospheric injections of sulfate aerosols is a decrease in stratospheric ozone. Here we show results from two general circulation models and two coupled chemistry climate models that have simulated stratospheric sulfate aerosol geoengineering as part of the Geoengineering Model Intercomparison Project (GeoMIP). Changes in photolysis rates and upwelling of ozone-poor air in the tropics reduce stratospheric ozone, suppression of the NOx cycle increases stratospheric ozone, and an increase in available surfaces for heterogeneous chemistry modulates reductions in ozone. On average, the models show a factor 20-40 increase of the sulfate aerosol surface area density (SAD) at 50 hPa in the tropics with respect to unperturbed background conditions and a factor 3-10 increase at mid-high latitudes. The net effect for a tropical injection rate of 5 Tg SO2 per year is a decrease in globally averaged ozone by 1.1-2.1 DU in the years 2040-2050 for three models which include heterogeneous chemistry on the sulfate aerosol surfaces. GISS-E2-R, a fully coupled general circulation model, performed simulations with no heterogeneous chemistry and a smaller aerosol size; it showed a decrease in ozone by 9.7 DU. After the year 2050, suppression of the NOx cycle becomes more important than destruction of ozone by ClOx, causing an increase in total stratospheric ozone. Contribution of ozone changes in this experiment to radiative forcing is 0.23 W m-2 in GISS-E2-R and less than 0.1 W m-2 in the other three models. Polar ozone depletion, due to enhanced formation of both sulfate aerosol SAD and polar stratospheric clouds, results in an average 5 percent increase in calculated surface UV-B.

  1. Sulfate geoengineering impact on methane transport and lifetime: results from the Geoengineering Model Intercomparison Project (GeoMIP)

    NASA Astrophysics Data System (ADS)

    Visioni, Daniele; Pitari, Giovanni; Aquila, Valentina; Tilmes, Simone; Cionni, Irene; Di Genova, Glauco; Mancini, Eva

    2017-09-01

    Sulfate geoengineering (SG), made by sustained injection of SO2 in the tropical lower stratosphere, may impact the CH4 abundance through several photochemical mechanisms affecting tropospheric OH and hence the methane lifetime. (a) The reflection of incoming solar radiation increases the planetary albedo and cools the surface, with a tropospheric H2O decrease. (b) The tropospheric UV budget is upset by the additional aerosol scattering and stratospheric ozone changes: the net effect is meridionally not uniform, with a net decrease in the tropics, thus producing less tropospheric O(1D). (c) The extratropical downwelling motion from the lower stratosphere tends to increase the sulfate aerosol surface area density available for heterogeneous chemical reactions in the mid-to-upper troposphere, thus reducing the amount of NOx and O3 production. (d) The tropical lower stratosphere is warmed by solar and planetary radiation absorption by the aerosols. The heating rate perturbation is highly latitude dependent, producing a stronger meridional component of the Brewer-Dobson circulation. The net effect on tropospheric OH due to the enhanced stratosphere-troposphere exchange may be positive or negative depending on the net result of different superimposed species perturbations (CH4, NOy, O3, SO4) in the extratropical upper troposphere and lower stratosphere (UTLS). In addition, the atmospheric stabilization resulting from the tropospheric cooling and lower stratospheric warming favors an additional decrease of the UTLS extratropical CH4 by lowering the horizontal eddy mixing. Two climate-chemistry coupled models are used to explore the above radiative, chemical and dynamical mechanisms affecting CH4 transport and lifetime (ULAQ-CCM and GEOSCCM). The CH4 lifetime may become significantly longer (by approximately 16 %) with a sustained injection of 8 Tg-SO2 yr-1 starting in the year 2020, which implies an increase of tropospheric CH4 (200 ppbv) and a positive indirect radiative

  2. Geoengineering to Avoid Overshoot: An Uncertainty Analysis

    NASA Astrophysics Data System (ADS)

    Tanaka, K.

    2009-04-01

    mitigation scenarios having overshoot are formulated. Optimal injection profiles (start-year and magnitude) for capping temperature rise at 2.0°C are calculated for each mitigation scenario. The sensitivity of such results to the uncertain parameters (climate sensitivity, tropospheric aerosol forcing, and ocean diffusivity) is then examined - in particular, I account for the inter-dependency of the estimates of these parameters such that they are consistent with historical observations (e.g. temperature records) by using an inverse estimation approach. I use the simple climate model ACC2 (Tanaka and Kriegler et al., 2007; Tanaka, 2008) - which (unlike Wigley's MAGICC model (Wigley and Raper, 2001)) includes an inversion setup that allows for the exploration of parameter inter-dependency based on historical observational constraints. References Crutzen, P. J. (2006) Albedo enhancement by stratospheric sulfur injections: a contribution to resolve a policy dilemma? Climatic Change, 77, 211-219. Rao, S., K. Riahi, E. Stehfest, D. van Vuuren, C. Cho, M. den Elzen, M. Isaac, J. van Vliet (2008) IMAGE and MESSAGE scenarios limiting GHG concentration to low levels. Interim Report at International Institute for Applied Systems Analysis (IIASA) IR-08-020. 57 pp. http://www.iiasa.ac.at/Admin/PUB/Documents/IR-08-020.pdf Robock, A. (2008) 20 reasons why geoengineering may be a bad idea. Bulletin of the Atomic Scientists, 64, 14-18. Tanaka, K., E. Kriegler, T. Bruckner, G. Hooss, W. Knorr, T. Raddatz (2007) Aggregated Carbon Cycle, Atmospheric Chemistry, and Climate Model (ACC2): description of the forward and inverse modes. Reports on Earth System Science No. 40. Max Planck Institute for Meteorology, Hamburg, Germany. 188 pp. http://www.mpimet.mpg.de/wissenschaft/publikationen/erdsystemforschung.html Tanaka, K. (2008) Inverse estimation for the simple Earth system model ACC2 and its applications. Ph.D. dissertation. Hamburg, Germany: Hamburg Universität, International Max Planck

  3. Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO2injection studied with the LMDZ-S3A model

    NASA Astrophysics Data System (ADS)

    Kleinschmitt, Christoph; Boucher, Olivier; Platt, Ulrich

    2018-02-01

    The enhancement of the stratospheric sulfate aerosol layer has been proposed as a method of geoengineering to abate global warming. Previous modelling studies found that stratospheric aerosol geoengineering (SAG) could effectively compensate for the warming by greenhouse gases on the global scale, but also that the achievable cooling effect per sulfur mass unit, i.e. the forcing efficiency, decreases with increasing injection rate. In this study we use the atmospheric general circulation model LMDZ with the sectional aerosol module S3A to determine how the forcing efficiency depends on the injected amount of SO2, the injection height, and the spatio-temporal pattern of injection. We find that the forcing efficiency may decrease more drastically for larger SO2 injections than previously estimated. As a result, the net instantaneous radiative forcing does not exceed the limit of -2 W m-2 for continuous equatorial SO2 injections and it decreases (in absolute value) for injection rates larger than 20 Tg S yr-1. In contrast to other studies, the net radiative forcing in our experiments is fairly constant with injection height (in a range 17 to 23 km) for a given amount of SO2 injected. Also, spreading the SO2 injections between 30° S and 30° N or injecting only seasonally from varying latitudes does not result in a significantly larger (i.e. more negative) radiative forcing. Other key characteristics of our simulations include a consequent stratospheric heating, caused by the absorption of solar and infrared radiation by the aerosol, and changes in stratospheric dynamics, with a collapse of the quasi-biennial oscillation at larger injection rates, which has impacts on the resulting spatial aerosol distribution, size, and optical properties. But it has to be noted that the complexity and uncertainty of stratospheric processes cause considerable disagreement among different modelling studies of stratospheric aerosol geoengineering. This may be addressed through detailed

  4. On solar geoengineering and climate uncertainty

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    MacMartin, Douglas; Kravitz, Benjamin S.; Rasch, Philip J.

    2015-09-03

    Uncertainty in the climate system response has been raised as a concern regarding solar geoengineering. Here we show that model projections of regional climate change outcomes may have greater agreement under solar geoengineering than with CO2 alone. We explore the effects of geoengineering on one source of climate system uncertainty by evaluating the inter-model spread across 12 climate models participating in the Geoengineering Model Intercomparison project (GeoMIP). The model spread in regional temperature and precipitation changes is reduced with CO2 and a solar reduction, in comparison to the case with increased CO2 alone. That is, the intermodel spread in predictionsmore » of climate change and the model spread in the response to solar geoengineering are not additive but rather partially cancel. Furthermore, differences in efficacy explain most of the differences between models in their temperature response to an increase in CO2 that is offset by a solar reduction. These conclusions are important for clarifying geoengineering risks.« less

  5. Exploring early public responses to geoengineering.

    PubMed

    Pidgeon, Nick; Corner, Adam; Parkhill, Karen; Spence, Alexa; Butler, Catherine; Poortinga, Wouter

    2012-09-13

    Proposals for geoengineering the Earth's climate are prime examples of emerging or 'upstream' technologies, because many aspects of their effectiveness, cost and risks are yet to be researched, and in many cases are highly uncertain. This paper contributes to the emerging debate about the social acceptability of geoengineering technologies by presenting preliminary evidence on public responses to geoengineering from two of the very first UK studies of public perceptions and responses. The discussion draws upon two datasets: qualitative data (from an interview study conducted in 42 households in 2009), and quantitative data (from a subsequent nationwide survey (n=1822) of British public opinion). Unsurprisingly, baseline awareness of geoengineering was extremely low in both cases. The data from the survey indicate that, when briefly explained to people, carbon dioxide removal approaches were preferred to solar radiation management, while significant positive correlations were also found between concern about climate change and support for different geoengineering approaches. We discuss some of the wider considerations that are likely to shape public perceptions of geoengineering as it enters the media and public sphere, and conclude that, aside from technical considerations, public perceptions are likely to prove a key element influencing the debate over questions of the acceptability of geoengineering proposals.

  6. Impacts of Geoengineering and Nuclear War on Chinese Agriculture

    NASA Astrophysics Data System (ADS)

    Xia, L.; Robock, A.

    2011-12-01

    geoengineering and nuclear war simulations for different regions in China. Without changes of agricultural technology, we found that in both climate scenarios, the national crop production decreases, but different regions responded differently, indicating that the climate under which agriculture is conducted is a key factor to determine the impacts of geoengineering and nuclear war on agriculture. In southern China, the cooling helps the rice and maize grow. In northern China, the cooling makes the temperatures so cold that it hurts crop productivity, and in western China, the reduction of precipitation causes failed crop growth. To adapt to geoengineering and nuclear war scenarios, we could substitute crops that would grow better in the perturbed climate, increase fertilizer usage, irrigate agricultural land, change planting date, or change to seeds which are tolerant of cooler and drier climates.

  7. Geoengineering: An Idea Whose Time Has Come?

    PubMed Central

    Resnik, David B.; Vallero, Daniel A.

    2013-01-01

    Some engineers and scientists recently have suggested that it would be prudent to consider engaging in geoengineering to mitigate global warming. Geoengineering differs from other methods for mitigating global warming because it involves a deliberate effort to affect the climate at a global scale. Although geoengineering is not a new idea, it has taken on added significance as a result of difficulties with implementing other proposals to mitigate climate change. While proponents of geoengineering admit that it can have significant risks for the environment and public health, many maintain that it is worth pursuing, given the failure of other means of mitigating global warming. Some environmental groups have voiced strong opposition to all forms of geoengineering. In this article, we examine arguments for and against geoengineering and discuss some policy options. We argue that specific geoengineering proposals should not be implemented until there is good evidence concerning their safety, efficacy, and feasibility, as well as a plan for oversight. International cooperation and public input should also be sought. Other methods for mitigating global warming should be aggressively pursued while geoengineering is under consideration. The promise of an engineering solution to global warming should not be used as an excuse to abandon or cut back current, climate mitigation efforts. PMID:23502911

  8. Geoengineering: An Idea Whose Time Has Come?

    PubMed

    Resnik, David B; Vallero, Daniel A

    2011-12-17

    Some engineers and scientists recently have suggested that it would be prudent to consider engaging in geoengineering to mitigate global warming. Geoengineering differs from other methods for mitigating global warming because it involves a deliberate effort to affect the climate at a global scale. Although geoengineering is not a new idea, it has taken on added significance as a result of difficulties with implementing other proposals to mitigate climate change. While proponents of geoengineering admit that it can have significant risks for the environment and public health, many maintain that it is worth pursuing, given the failure of other means of mitigating global warming. Some environmental groups have voiced strong opposition to all forms of geoengineering. In this article, we examine arguments for and against geoengineering and discuss some policy options. We argue that specific geoengineering proposals should not be implemented until there is good evidence concerning their safety, efficacy, and feasibility, as well as a plan for oversight. International cooperation and public input should also be sought. Other methods for mitigating global warming should be aggressively pursued while geoengineering is under consideration. The promise of an engineering solution to global warming should not be used as an excuse to abandon or cut back current, climate mitigation efforts.

  9. Regional Climate Impacts of Stabilizing Global Warming at 1.5 K Using Solar Geoengineering

    NASA Astrophysics Data System (ADS)

    Jones, Anthony C.; Hawcroft, Matthew K.; Haywood, James M.; Jones, Andy; Guo, Xiaoran; Moore, John C.

    2018-02-01

    The 2015 Paris Agreement aims to limit global warming to well below 2 K above preindustrial levels, and to pursue efforts to limit global warming to 1.5 K, in order to avert dangerous climate change. However, current greenhouse gas emissions targets are more compatible with scenarios exhibiting end-of-century global warming of 2.6-3.1 K, in clear contradiction to the 1.5 K target. In this study, we use a global climate model to investigate the climatic impacts of using solar geoengineering by stratospheric aerosol injection to stabilize global-mean temperature at 1.5 K for the duration of the 21st century against three scenarios spanning the range of plausible greenhouse gas mitigation pathways (RCP2.6, RCP4.5, and RCP8.5). In addition to stabilizing global mean temperature and offsetting both Arctic sea-ice loss and thermosteric sea-level rise, we find that solar geoengineering could effectively counteract enhancements to the frequency of extreme storms in the North Atlantic and heatwaves in Europe, but would be less effective at counteracting hydrological changes in the Amazon basin and North Atlantic storm track displacement. In summary, solar geoengineering may reduce global mean impacts but is an imperfect solution at the regional level, where the effects of climate change are experienced. Our results should galvanize research into the regionality of climate responses to solar geoengineering.

  10. Geoengineering as an optimization problem

    NASA Astrophysics Data System (ADS)

    Ban-Weiss, George A.; Caldeira, Ken

    2010-07-01

    There is increasing evidence that Earth's climate is currently warming, primarily due to emissions of greenhouse gases from human activities, and Earth has been projected to continue warming throughout this century. Scientists have begun to investigate the potential for geoengineering options for reducing surface temperatures and whether such options could possibly contribute to environmental risk reduction. One proposed method involves deliberately increasing aerosol loading in the stratosphere to scatter additional sunlight to space. Previous modeling studies have attempted to predict the climate consequences of hypothetical aerosol additions to the stratosphere. These studies have shown that this method could potentially reduce surface temperatures, but could not recreate a low-CO2 climate in a high-CO2 world. In this study, we attempt to determine the latitudinal distribution of stratospheric aerosols that would most closely achieve a low-CO2 climate despite high CO2 levels. Using the NCAR CAM3.1 general circulation model, we find that having a stratospheric aerosol loading in polar regions higher than that in tropical regions leads to a temperature distribution that is more similar to the low-CO2 climate than that yielded by a globally uniform loading. However, such polar weighting of stratospheric sulfate tends to degrade the degree to which the hydrological cycle is restored, and thus does not markedly contribute to improved recovery of a low-CO2 climate. In the model, the optimal latitudinally varying aerosol distributions diminished the rms zonal mean land temperature change from a doubling of CO2 by 94% and the rms zonal mean land precipitation minus evaporation change by 74%. It is important to note that this idealized study represents a first attempt at optimizing the engineering of climate using a general circulation model; uncertainties are high and not all processes that are important in reality are modeled.

  11. Transient climate-carbon simulations of planetary geoengineering.

    PubMed

    Matthews, H Damon; Caldeira, Ken

    2007-06-12

    Geoengineering (the intentional modification of Earth's climate) has been proposed as a means of reducing CO2-induced climate warming while greenhouse gas emissions continue. Most proposals involve managing incoming solar radiation such that future greenhouse gas forcing is counteracted by reduced solar forcing. In this study, we assess the transient climate response to geoengineering under a business-as-usual CO2 emissions scenario by using an intermediate-complexity global climate model that includes an interactive carbon cycle. We find that the climate system responds quickly to artificially reduced insolation; hence, there may be little cost to delaying the deployment of geoengineering strategies until such a time as "dangerous" climate change is imminent. Spatial temperature patterns in the geoengineered simulation are comparable with preindustrial temperatures, although this is not true for precipitation. Carbon sinks in the model increase in response to geoengineering. Because geoengineering acts to mask climate warming, there is a direct CO2-driven increase in carbon uptake without an offsetting temperature-driven suppression of carbon sinks. However, this strengthening of carbon sinks, combined with the potential for rapid climate adjustment to changes in solar forcing, leads to serious consequences should geoengineering fail or be stopped abruptly. Such a scenario could lead to very rapid climate change, with warming rates up to 20 times greater than present-day rates. This warming rebound would be larger and more sustained should climate sensitivity prove to be higher than expected. Thus, employing geoengineering schemes with continued carbon emissions could lead to severe risks for the global climate system.

  12. Solar geoengineering as part of an overall strategy for meeting the 1.5°C Paris target.

    PubMed

    MacMartin, Douglas G; Ricke, Katharine L; Keith, David W

    2018-05-13

    Solar geoengineering refers to deliberately reducing net radiative forcing by reflecting some sunlight back to space, in order to reduce anthropogenic climate changes; a possible such approach would be adding aerosols to the stratosphere. If future mitigation proves insufficient to limit the rise in global mean temperature to less than 1.5°C above preindustrial, it is plausible that some additional and limited deployment of solar geoengineering could reduce climate damages. That is, these approaches could eventually be considered as part of an overall strategy to manage the risks of climate change, combining emissions reduction, net-negative emissions technologies and solar geoengineering to meet climate goals. We first provide a physical-science review of current research, research trends and some of the key gaps in knowledge that would need to be addressed to support informed decisions. Next, since few climate model simulations have considered these limited-deployment scenarios, we synthesize prior results to assess the projected response if solar geoengineering were used to limit global mean temperature to 1.5°C above preindustrial in an overshoot scenario that would otherwise peak near 3°C. While there are some important differences, the resulting climate is closer in many respects to a climate where the 1.5°C target is achieved through mitigation alone than either is to the 3°C climate with no geoengineering. This holds for both regional temperature and precipitation changes; indeed, there are no regions where a majority of models project that this moderate level of geoengineering would produce a statistically significant shift in precipitation further away from preindustrial levels.This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. © 2018 The Author(s).

  13. Solar geoengineering as part of an overall strategy for meeting the 1.5°C Paris target

    NASA Astrophysics Data System (ADS)

    MacMartin, Douglas G.; Ricke, Katharine L.; Keith, David W.

    2018-05-01

    Solar geoengineering refers to deliberately reducing net radiative forcing by reflecting some sunlight back to space, in order to reduce anthropogenic climate changes; a possible such approach would be adding aerosols to the stratosphere. If future mitigation proves insufficient to limit the rise in global mean temperature to less than 1.5°C above preindustrial, it is plausible that some additional and limited deployment of solar geoengineering could reduce climate damages. That is, these approaches could eventually be considered as part of an overall strategy to manage the risks of climate change, combining emissions reduction, net-negative emissions technologies and solar geoengineering to meet climate goals. We first provide a physical-science review of current research, research trends and some of the key gaps in knowledge that would need to be addressed to support informed decisions. Next, since few climate model simulations have considered these limited-deployment scenarios, we synthesize prior results to assess the projected response if solar geoengineering were used to limit global mean temperature to 1.5°C above preindustrial in an overshoot scenario that would otherwise peak near 3°C. While there are some important differences, the resulting climate is closer in many respects to a climate where the 1.5°C target is achieved through mitigation alone than either is to the 3°C climate with no geoengineering. This holds for both regional temperature and precipitation changes; indeed, there are no regions where a majority of models project that this moderate level of geoengineering would produce a statistically significant shift in precipitation further away from preindustrial levels. This article is part of the theme issue `The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.

  14. Tibetan Plateau glacier and hydrological change under stratospheric aerosol injection

    NASA Astrophysics Data System (ADS)

    Ji, D.

    2017-12-01

    As an important inland freshwater resource, mountain glaciers are highly related to human life, they provide water for many large rivers and play a very important role in regional water cycles. The response of mountain glaciers to future climate change is a topic of concern especially to the many people who rely on glacier-fed rivers for purposes such as irrigation. Geoengineering by stratospheric aerosol injection is a method of offsetting the global temperature rise from greenhouse gases. How the geoengineering by stratospheric aerosol injection affects the mass balance of mountain glaciers and adjacent river discharge is little understood. In this study, we use regional climate model WRF and catchment-based river model CaMa-Flood to study the impacts of stratospheric aerosol injection to Tibetan Plateau glacier mass balance and adjacent river discharge. To facilitate mountain glacier mass balance study, we improve the description of mountain glacier in the land surface scheme of WRF. The improvements include: (1) a fine mesh nested in WRF horizontal grid to match the highly non-uniform spatial distribution of the mountain glaciers, (2) revising the radiation flux at the glacier surface considering the surrounding terrain. We use the projections of five Earth system models for CMIP5 rcp45 and GeoMIP G4 scenarios to drive the WRF and CaMa-Flood models. The G4 scenario, which uses stratospheric aerosols to reduce the incoming shortwave while applying the rcp4.5 greenhouse gas forcing, starts stratospheric sulfate aerosol injection at a rate of 5 Tg per year over the period 2020-2069. The ensemble projections suggest relatively slower glacier mass loss rates and reduced river discharge at Tibetan Plateau and adjacent regions under geoengineering scenario by stratospheric aerosol injection.

  15. Geoengineering the climate: an overview and update.

    PubMed

    Shepherd, J G

    2012-09-13

    The climate change that we are experiencing now is caused by an increase in greenhouse gases due to human activities, including burning fossil fuels, agriculture and deforestation. There is now widespread belief that a global warming of greater than 2(°)C above pre-industrial levels would be dangerous and should therefore be avoided. However, despite growing concerns over climate change and numerous international attempts to agree on reductions of global CO(2) emissions, these have continued to climb. This has led some commentators to suggest more radical 'geoengineering' alternatives to conventional mitigation by reductions in CO(2) emissions. Geoengineering is deliberate intervention in the climate system to counteract man-made global warming. There are two main classes of geoengineering: direct carbon dioxide removal and solar radiation management that aims to cool the planet by reflecting more sunlight back to space. The findings of the review of geoengineering carried out by the UK Royal Society in 2009 are summarized here, including the climate effects, costs, risks and research and governance needs for various approaches. The possible role of geoengineering in a portfolio of responses to climate change is discussed, and various recent initiatives to establish good governance of research activity are reviewed. Key findings include the following.- Geoengineering is not a magic bullet and not an alternative to emissions reductions. - Cutting global greenhouse gas emissions must remain our highest priority. (i) But this is proving to be difficult, and geoengineering may be useful to support it. - Geoengineering is very likely to be technically possible. (i) However, there are major uncertainties and potential risks concerning effectiveness, costs and social and environmental impacts. - Much more research is needed, as well as public engagement and a system of regulation (for both deployment and for possible large-scale field tests). - The acceptability of

  16. Development of geopolitically relevant ranking criteria for geoengineering methods

    NASA Astrophysics Data System (ADS)

    Boyd, Philip W.

    2016-11-01

    A decade has passed since Paul Crutzen published his editorial essay on the potential for stratospheric geoengineering to cool the climate in the Anthropocene. He synthesized the effects of the 1991 Pinatubo eruption on the planet's radiative budget and used this large-scale event to broaden and deepen the debate on the challenges and opportunities of large-scale geoengineering. Pinatubo had pronounced effects, both in the short and longer term (months to years), on the ocean, land, and the atmosphere. This rich set of data on how a large-scale natural event influences many regional and global facets of the Earth System provides a comprehensive viewpoint to assess the wider ramifications of geoengineering. Here, I use the Pinatubo archives to develop a range of geopolitically relevant ranking criteria for a suite of different geoengineering approaches. The criteria focus on the spatial scales needed for geoengineering and whether large-scale dispersal is a necessary requirement for a technique to deliver significant cooling or carbon dioxide reductions. These categories in turn inform whether geoengineering approaches are amenable to participation (the "democracy of geoengineering") and whether they will lead to transboundary issues that could precipitate geopolitical conflicts. The criteria provide the requisite detail to demarcate different geoengineering approaches in the context of geopolitics. Hence, they offer another tool that can be used in the development of a more holistic approach to the debate on geoengineering.

  17. Photophoretic levitation of engineered aerosols for geoengineering

    PubMed Central

    Keith, David W.

    2010-01-01

    Aerosols could be injected into the upper atmosphere to engineer the climate by scattering incident sunlight so as to produce a cooling tendency that may mitigate the risks posed by the accumulation of greenhouse gases. Analysis of climate engineering has focused on sulfate aerosols. Here I examine the possibility that engineered nanoparticles could exploit photophoretic forces, enabling more control over particle distribution and lifetime than is possible with sulfates, perhaps allowing climate engineering to be accomplished with fewer side effects. The use of electrostatic or magnetic materials enables a class of photophoretic forces not found in nature. Photophoretic levitation could loft particles above the stratosphere, reducing their capacity to interfere with ozone chemistry; and, by increasing particle lifetimes, it would reduce the need for continual replenishment of the aerosol. Moreover, particles might be engineered to drift poleward enabling albedo modification to be tailored to counter polar warming while minimizing the impact on equatorial climates. PMID:20823254

  18. Photophoretic levitation of engineered aerosols for geoengineering.

    PubMed

    Keith, David W

    2010-09-21

    Aerosols could be injected into the upper atmosphere to engineer the climate by scattering incident sunlight so as to produce a cooling tendency that may mitigate the risks posed by the accumulation of greenhouse gases. Analysis of climate engineering has focused on sulfate aerosols. Here I examine the possibility that engineered nanoparticles could exploit photophoretic forces, enabling more control over particle distribution and lifetime than is possible with sulfates, perhaps allowing climate engineering to be accomplished with fewer side effects. The use of electrostatic or magnetic materials enables a class of photophoretic forces not found in nature. Photophoretic levitation could loft particles above the stratosphere, reducing their capacity to interfere with ozone chemistry; and, by increasing particle lifetimes, it would reduce the need for continual replenishment of the aerosol. Moreover, particles might be engineered to drift poleward enabling albedo modification to be tailored to counter polar warming while minimizing the impact on equatorial climates.

  19. Shortwave radiative forcing, rapid adjustment, and feedback to the surface by sulfate geoengineering: analysis of the Geoengineering Model Intercomparison Project G4 scenario

    DOE PAGES

    Kashimura, Hiroki; Abe, Manabu; Watanabe, Shingo; ...

    2017-03-08

    This paper evaluates the forcing, rapid adjustment, and feedback of net shortwave radiation at the surface in the G4 experiment of the Geoengineering Model Intercomparison Project by analysing outputs from six participating models. G4 involves injection of 5 Tg yr -1 of SO 2, a sulfate aerosol precursor, into the lower stratosphere from year 2020 to 2069 against a background scenario of RCP4.5. A single-layer atmospheric model for shortwave radiative transfer is used to estimate the direct forcing of solar radiation management (SRM), and rapid adjustment and feedbacks from changes in the water vapour amount, cloud amount, and surface albedo (compared with RCP4.5). The analysismore » shows that the globally and temporally averaged SRM forcing ranges from -3.6 to -1.6 W m -2, depending on the model. The sum of the rapid adjustments and feedback effects due to changes in the water vapour and cloud amounts increase the downwelling shortwave radiation at the surface by approximately 0.4 to 1.5 W m -2 and hence weaken the effect of SRM by around 50 %. The surface albedo changes decrease the net shortwave radiation at the surface; it is locally strong (~-4 W m -2) in snow and sea ice melting regions, but minor for the global average. The analyses show that the results of the G4 experiment, which simulates sulfate geoengineering, include large inter-model variability both in the direct SRM forcing and the shortwave rapid adjustment from change in the cloud amount, and imply a high uncertainty in modelled processes of sulfate aerosols and clouds.« less

  20. Geo-Engineering through Internet Informatics (GEMINI)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Doveton, John H.; Watney, W. Lynn

    The program, for development and methodologies, was a 3-year interdisciplinary effort to develop an interactive, integrated Internet Website named GEMINI (Geo-Engineering Modeling through Internet Informatics) that would build real-time geo-engineering reservoir models for the Internet using the latest technology in Web applications.

  1. Global change - Geoengineering and space exploration

    NASA Technical Reports Server (NTRS)

    Jenkins, Lyle M.

    1992-01-01

    Geoengineering options and alternatives are proposed for mitigating the effects of global climate change and depletion of the ozone layer. Geoengineering options were discussed by the National Academy of Science Panel on the Policy Implications of Greenhouse Warming. Several of the ideas conveyed in their published report are space-based or depend on space systems for implementation. Among the geoengineering options using space that are discussed include the use of space power systems as an alternative to fossil fuels for generating electricity, the use of lunar He-3 to aid in the development of fusion energy, and the establishment of a lunar power system for solar energy conversion and electric power beaming back to earth. Other geoengineering options are discussed. They include the space-based modulation of hurricane forces and two space-based approaches in dealing with ozone layer depletion. The engineering challenges and policy implementation issues are discussed for these geongineering options.

  2. Towards a comprehensive climate impacts assessment of solar geoengineering

    NASA Astrophysics Data System (ADS)

    Irvine, Peter J.; Kravitz, Ben; Lawrence, Mark G.; Gerten, Dieter; Caminade, Cyril; Gosling, Simon N.; Hendy, Erica J.; Kassie, Belay T.; Kissling, W. Daniel; Muri, Helene; Oschlies, Andreas; Smith, Steven J.

    2017-01-01

    Despite a growing literature on the climate response to solar geoengineering—proposals to cool the planet by increasing the planetary albedo—there has been little published on the impacts of solar geoengineering on natural and human systems such as agriculture, health, water resources, and ecosystems. An understanding of the impacts of different scenarios of solar geoengineering deployment will be crucial for informing decisions on whether and how to deploy it. Here we review the current state of knowledge about impacts of a solar-geoengineered climate and identify the major research gaps. We suggest that a thorough assessment of the climate impacts of a range of scenarios of solar geoengineering deployment is needed and can be built upon existing frameworks. However, solar geoengineering poses a novel challenge for climate impacts research as the manner of deployment could be tailored to pursue different objectives making possible a wide range of climate outcomes. We present a number of ideas for approaches to extend the survey of climate impacts beyond standard scenarios of solar geoengineering deployment to address this challenge. Reducing the impacts of climate change is the fundamental motivator for emissions reductions and for considering whether and how to deploy solar geoengineering. This means that the active engagement of the climate impacts research community will be important for improving the overall understanding of the opportunities, challenges, and risks presented by solar geoengineering.

  3. Cloud-Resolving Model Simulations of Aerosol-Cloud Interactions Triggered by Strong Aerosol Emissions in the Arctic

    NASA Astrophysics Data System (ADS)

    Wang, H.; Kravitz, B.; Rasch, P. J.; Morrison, H.; Solomon, A.

    2014-12-01

    Previous process-oriented modeling studies have highlighted the dependence of effectiveness of cloud brightening by aerosols on cloud regimes in warm marine boundary layer. Cloud microphysical processes in clouds that contain ice, and hence the mechanisms that drive aerosol-cloud interactions, are more complicated than in warm clouds. Interactions between ice particles and liquid drops add additional levels of complexity to aerosol effects. A cloud-resolving model is used to study aerosol-cloud interactions in the Arctic triggered by strong aerosol emissions, through either geoengineering injection or concentrated sources such as shipping and fires. An updated cloud microphysical scheme with prognostic aerosol and cloud particle numbers is employed. Model simulations are performed in pure super-cooled liquid and mixed-phase clouds, separately, with or without an injection of aerosols into either a clean or a more polluted Arctic boundary layer. Vertical mixing and cloud scavenging of particles injected from the surface is still quite efficient in the less turbulent cold environment. Overall, the injection of aerosols into the Arctic boundary layer can delay the collapse of the boundary layer and increase low-cloud albedo. The pure liquid clouds are more susceptible to the increase in aerosol number concentration than the mixed-phase clouds. Rain production processes are more effectively suppressed by aerosol injection, whereas ice precipitation (snow) is affected less; thus the effectiveness of brightening mixed-phase clouds is lower than for liquid-only clouds. Aerosol injection into a clean boundary layer results in a greater cloud albedo increase than injection into a polluted one, consistent with current knowledge about aerosol-cloud interactions. Unlike previous studies investigating warm clouds, the impact of dynamical feedback due to precipitation changes is small. According to these results, which are dependent upon the representation of ice nucleation

  4. Towards a comprehensive climate impacts assessment of solar geoengineering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Irvine, Peter J.; Kravitz, Ben; Lawrence, Mark G.

    Despite a growing literature on the climate response to solar geoengineering—proposals to cool the planet by increasing the planetary albedo—there has been little published on the impacts of solar geoengineering on natural and human systems such as agriculture, health, water resources, and ecosystems. An understanding of the impacts of different scenarios of solar geoengineering deployment will be crucial for informing decisions on whether and how to deploy it. Here we review the current state of knowledge about impacts of a solar-geoengineered climate and identify the major research gaps. We suggest that a thorough assessment of the climate impacts of amore » range of scenarios of solar geoengineering deployment is needed and can be built upon existing frameworks. However, solar geoengineering poses a novel challenge for climate impacts research as the manner of deployment could be tailored to pursue different objectives making possible a wide range of climate outcomes. We present a number of ideas for approaches to extend the survey of climate impacts beyond standard scenarios of solar geoengineering deployment to address this challenge. Reducing the impacts of climate change is the fundamental motivator for emissions reductions and for considering whether and how to deploy solar geoengineering. This means that the active engagement of the climate impacts research community will be important for improving the overall understanding of the opportunities, challenges, and risks presented by solar geoengineering.« less

  5. Towards a comprehensive climate impacts assessment of solar geoengineering

    DOE PAGES

    Irvine, Peter J.; Kravitz, Ben; Lawrence, Mark G.; ...

    2016-11-23

    Despite a growing literature on the climate response to solar geoengineering—proposals to cool the planet by increasing the planetary albedo—there has been little published on the impacts of solar geoengineering on natural and human systems such as agriculture, health, water resources, and ecosystems. An understanding of the impacts of different scenarios of solar geoengineering deployment will be crucial for informing decisions on whether and how to deploy it. Here we review the current state of knowledge about impacts of a solar-geoengineered climate and identify the major research gaps. We suggest that a thorough assessment of the climate impacts of amore » range of scenarios of solar geoengineering deployment is needed and can be built upon existing frameworks. However, solar geoengineering poses a novel challenge for climate impacts research as the manner of deployment could be tailored to pursue different objectives making possible a wide range of climate outcomes. We present a number of ideas for approaches to extend the survey of climate impacts beyond standard scenarios of solar geoengineering deployment to address this challenge. Reducing the impacts of climate change is the fundamental motivator for emissions reductions and for considering whether and how to deploy solar geoengineering. This means that the active engagement of the climate impacts research community will be important for improving the overall understanding of the opportunities, challenges, and risks presented by solar geoengineering.« less

  6. The Hydrological Impact of Geoengineering in the Geoengineering Model Intercomparison Project (GeoMIP)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tilmes, S.; Fasullo, John; Lamarque, J.-F.

    2013-10-14

    Abstract: The hydrologic impact of enhancing Earth’s albedo due to solar radiation management (SRM) is investigated using simulations from 12 models contributing to the Geoengineering Model Intercomparison Project (GeoMIP). An artificial experiment is investigated, where global mean temperature is preserved at pre-industrial conditions, while atmospheric carbon dioxide concentrations are quadrupled. The associated reduction of downwelling surface solar radiation in a high CO2 environment leads to a reduction of global evaporation of 10% and 4% and precipitation of 6.1% and 6.3% over land and ocean, respectively. An initial reduction of latent heat flux at the surface is largely driven by reducedmore » evapotranspiration over land with instantly increasing CO2 concentrations in both experiments. A warming surface associated with the transient adjustment in the 4xCO2 experiment further generates an increase of global precipitation, with considerable regional changes, such as a significant precipitation reduction of 7% for the North American summer monsoon. Reduced global precipitation persists in the geoengineered experiment where temperatures are stabilized, with considerable regional rainfall deficits. Precipitation reductions that are consistent in sign across models are identified in the geoengineered experiment over monsoonal land regions of East Asia (6%), North America (7%), South America (6%) and South Africa (5%). In contrast to the 4xCO2 experiment, where the frequency of months with heavy precipitation intensity is increased by over 50%, it is reduced by up to 20% in the geoengineering scenario . The reduction in heavy precipitation is more pronounced over land than over the ocean, and accompanies a stronger reduction in evaporation over land. For northern mid-latitudes, maximum precipitation reduction over land ranges from 1 to 16% for individual models. For 45-65°N, the frequency of median to high intensity precipitation in summer is strongly

  7. Sensitivity of Methane Lifetime and Transport to Sulfate Geoengineering

    NASA Astrophysics Data System (ADS)

    Aquila, V.; Pitari, G.; Tilmes, S.; Cionni, I.; de Luca, N.; Di Genova, G.; Iachetti, D.

    2014-12-01

    Sulfate geoengineering, made by sustained injection of SO2 in the tropical lower stratosphere, may impact the abundance of tropospheric methane through several photochemical mechanisms affecting the tropospheric OH abundance and hence the methane lifetime. Changes of the stratospheric Brewer-Dobson circulation also play a role in the upper tropospheric CH4 transport. Three mechanisms lead to lower OH concentrations and a longer CH4 lifetime: (a) solar radiation scattering increases the planetary albedo and cools the surface, with a tropospheric water vapor decrease as a response to this cooling. (b) The tropospheric UV budget is upset by the additional aerosol scattering and stratospheric ozone changes: the net effect is meridionally not uniform, with a net decrease in the tropics, thus producing less tropospheric O(1D). (c) The extra-tropical downwelling motion from the lower stratosphere tends to increase the sulfate aerosol surface area density available for heterogeneous chemical reactions in the mid-upper troposphere, thus reducing the amount of NOx and tropospheric O3 production. On the other hand, the tropical lower stratosphere is warmed by solar and planetary radiation absorption by the aerosols. The heating rates perturbation are strongly latitude dependent, producing a significant change of the pole-to-equator temperature gradient and mean zonal wind distribution, with a net increase of tropical upwelling. A stronger meridional component of the Brewer-Dobson circulation increases the extra-tropical stratosphere to troposphere transport of CH4 poorer air, resulting in less CH4 transported in the UTLS. The net effect on tropospheric OH may be positive or negative depending on the net result of different superimposed species perturbations in the UTLS, i.e. CH4 (negative), NOy and O3 (positive). Three climate-chemistry coupled models are used here to explore the above radiative, chemical and dynamical mechanisms affecting the methane lifetime (ULAQ

  8. New Results from the Geoengineering Model Intercomparison Project (GeoMIP)

    NASA Astrophysics Data System (ADS)

    Robock, A.; Kravitz, B.

    2013-12-01

    The Geoengineering Model Intercomparison Project (GeoMIP) was designed to determine robust climate system model responses to Solar Radiation Management (SRM). While mitigation (reducing greenhouse gases emissions) is the most effective way of reducing future climate change, SRM (the deliberate modification of incoming solar radiation) has been proposed as a means of temporarily alleviating some of the effects of global warming. For society to make informed decisions as to whether SRM should ever be implemented, information is needed on the benefits, risks, and side effects, and GeoMIP seeks to aid in that endeavor. GeoMIP has organized four standardized climate model simulations involving reduction of insolation or increased amounts of stratospheric sulfate aerosols to counteract increasing greenhouse gases. Thirteen comprehensive atmosphere-ocean general circulation models have participated in the project so far. GeoMIP is a 'CMIP Coordinated Experiment' as part of the Climate Model Intercomparison Project 5 (CMIP5) and has been endorsed by SPARC (Stratosphere-troposphere Processes And their Role in Climate). GeoMIP has held three international workshops and has produced a number of recent journal articles. GeoMIP has found that if increasing greenhouse gases could be counteracted with insolation reduction, the global average temperature could be kept constant, but global average precipitation would reduce, particularly in summer monsoon regions around the world. Temperature changes would also not be uniform. The tropics would cool, but high latitudes would warm, with continuing, but reduced sea ice and ice sheet melting. Temperature extremes would still increase, but not as much as without SRM. If SRM were halted all at once, there would be rapid temperature and precipitation increases at 5-10 times the rates from gradual global warming. SRM combined with CO2 fertilization would have small impacts on rice production in China, but would increase maize production

  9. Impact of sulphate geoengineering on rice yield in China

    NASA Astrophysics Data System (ADS)

    Zhan, Pei; Zhu, Wenquan; Zheng, Zhoutao; Zhang, Donghai; Li, Nan

    2017-04-01

    Sulphate geoengineering is one of the mostly discussed mitigation methods against global warming for its feasibility and inexpensiveness. With SO2 consistently injected into the stratosphere to balance the radiative force caused by anthropogenic emission, sulphate engineering will significantly influence the climate over the planet and moreover, affect agriculture productivity. In our study, BNU-ESM model was used to simulate the impact of sulphate engineering on climate and ORYZA(v3) model was used to simulate the impact of climate change on rice yield/production in China. Firstly, the ORYZA(v3) model was evaluated and calibrated using daily climate data, management data and county-level yield record during 1981-2010 in 19 provinces in China. Then climate anomalies of sulphate geoengineering simulated by BNU-ESM model was used to perturb the observed climate data over 318 stations evenly distribute in China during 1981-2010. In our study, a 30-year climate record of anomalies were extracted from BNU-ESM model to match the observed climate data, which consisted of a 15-year geoengineering record and a 15-year post-geoengineering record. Lastly, the perturbed climate data was used in calibrated-ORYZA(v3) model to simulate the rice yield over the 318 stations, which were later averaged into corresponding provincial yield. The results showed that (1) geoengineering would balance solar radiation for approximate 140 W ṡ m-2 per year (about 0.9 K per year in temperature), which would meet the pre-concerted goal of geoengineering but it would take only about 3 years for temperature to recover after the termination of geoengineering. In spite of this, there would be a declining of vapour pressure for about 0.12 KPa per year during geoengineering period, and it would take about 15 years to recover during post-geoengineering period. The simulation showed that geoengineering would have a little declining impact on average precipitation and would not have much impact on wind

  10. Ethics as an Integral Component of Geoengineering Analysis

    NASA Astrophysics Data System (ADS)

    Haqq-Misra, J.; Tuana, N.; Keller, K.; Sriver, R. L.; Svoboda, T.; Tonkonojenkov, R.; Irvine, P. J.

    2011-12-01

    Concerns about the risks of unmitigated greenhouse gas emissions are growing. At the same time, confidence is declining that international policy agreements will succeed in considerably lowering anthropogenic greenhouse gas emissions. Perhaps as a result, various geoengineering solutions are gaining attention and credibility as a way to manage climate change. Serious consideration is currently being given to proposals to cool the planet through solar-radiation management (SRM). Here we analyze how the unique and nontrivial risks of geoengineering strategies pose fundamental questions at the interface between science and ethics. We define key open questions to analyze SRM geoengineering proposals, which include whether SRM can be tested, how quickly learning could occur, normative decisions embedded in how different climate trajectories are valued, and justice issues regarding distribution of the harms and benefits of geoengineering. To ensure that ethical analyses are coupled with scientific analyses of this form of geoengineering, we advocate that funding agencies recognize the essential nature of this coupled research by establishing an Ethical, Legal, and Social Implications (ELSI) program for SRM.

  11. Towards legitimacy of the solar geoengineering research enterprise

    NASA Astrophysics Data System (ADS)

    Frumhoff, Peter C.; Stephens, Jennie C.

    2018-05-01

    Mounting evidence that even aggressive reductions in net emissions of greenhouse gases will be insufficient to limit global climate risks is increasing calls for atmospheric experiments to better understand the risks and implications of also deploying solar geoengineering technologies to reflect sunlight and rapidly lower surface temperatures. But solar geoengineering research itself poses significant environmental and geopolitical risks. Given limited societal awareness and public dialogue about this climate response option, conducting such experiments without meaningful societal engagement could galvanize opposition to solar geoengineering research from civil society, including the most climate vulnerable communities who are among its intended beneficiaries. Here, we explore whether and how a solar geoengineering research enterprise might be developed in a way that promotes legitimacy as well as scientific credibility and policy relevance. We highlight the distinctive responsibilities of researchers and research funders to ensure that solar geoengineering research proposals are subject to legitimate societal review and scrutiny, recommend steps they can take to strive towards legitimacy and call on them to be explicitly open to multiple potential outcomes, including the societal rejection or considerable alteration of the solar geoengineering research enterprise. This article is part of the theme issue `The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.

  12. Towards legitimacy of the solar geoengineering research enterprise

    PubMed Central

    Stephens, Jennie C.

    2018-01-01

    Mounting evidence that even aggressive reductions in net emissions of greenhouse gases will be insufficient to limit global climate risks is increasing calls for atmospheric experiments to better understand the risks and implications of also deploying solar geoengineering technologies to reflect sunlight and rapidly lower surface temperatures. But solar geoengineering research itself poses significant environmental and geopolitical risks. Given limited societal awareness and public dialogue about this climate response option, conducting such experiments without meaningful societal engagement could galvanize opposition to solar geoengineering research from civil society, including the most climate vulnerable communities who are among its intended beneficiaries. Here, we explore whether and how a solar geoengineering research enterprise might be developed in a way that promotes legitimacy as well as scientific credibility and policy relevance. We highlight the distinctive responsibilities of researchers and research funders to ensure that solar geoengineering research proposals are subject to legitimate societal review and scrutiny, recommend steps they can take to strive towards legitimacy and call on them to be explicitly open to multiple potential outcomes, including the societal rejection or considerable alteration of the solar geoengineering research enterprise. This article is part of the theme issue ‘The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. PMID:29610369

  13. Towards legitimacy of the solar geoengineering research enterprise.

    PubMed

    Frumhoff, Peter C; Stephens, Jennie C

    2018-05-13

    Mounting evidence that even aggressive reductions in net emissions of greenhouse gases will be insufficient to limit global climate risks is increasing calls for atmospheric experiments to better understand the risks and implications of also deploying solar geoengineering technologies to reflect sunlight and rapidly lower surface temperatures. But solar geoengineering research itself poses significant environmental and geopolitical risks. Given limited societal awareness and public dialogue about this climate response option, conducting such experiments without meaningful societal engagement could galvanize opposition to solar geoengineering research from civil society, including the most climate vulnerable communities who are among its intended beneficiaries. Here, we explore whether and how a solar geoengineering research enterprise might be developed in a way that promotes legitimacy as well as scientific credibility and policy relevance. We highlight the distinctive responsibilities of researchers and research funders to ensure that solar geoengineering research proposals are subject to legitimate societal review and scrutiny, recommend steps they can take to strive towards legitimacy and call on them to be explicitly open to multiple potential outcomes, including the societal rejection or considerable alteration of the solar geoengineering research enterprise.This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. © 2018 The Authors.

  14. Solar geoengineering to limit the rate of temperature change.

    PubMed

    MacMartin, Douglas G; Caldeira, Ken; Keith, David W

    2014-12-28

    Solar geoengineering has been suggested as a tool that might reduce damage from anthropogenic climate change. Analysis often assumes that geoengineering would be used to maintain a constant global mean temperature. Under this scenario, geoengineering would be required either indefinitely (on societal time scales) or until atmospheric CO2 concentrations were sufficiently reduced. Impacts of climate change, however, are related to the rate of change as well as its magnitude. We thus describe an alternative scenario in which solar geoengineering is used only to constrain the rate of change of global mean temperature; this leads to a finite deployment period for any emissions pathway that stabilizes global mean temperature. The length of deployment and amount of geoengineering required depends on the emissions pathway and allowable rate of change, e.g. in our simulations, reducing the maximum approximately 0.3°C per decade rate of change in an RCP 4.5 pathway to 0.1°C per decade would require geoengineering for 160 years; under RCP 6.0, the required time nearly doubles. We demonstrate that feedback control can limit rates of change in a climate model. Finally, we note that a decision to terminate use of solar geoengineering does not automatically imply rapid temperature increases: feedback could be used to limit rates of change in a gradual phase-out. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  15. Geoengineering: re-making climate for profit or humanitarian intervention?

    PubMed

    Buck, Holly Jean

    2012-01-01

    Climate engineering, or geoengineering, refers to large-scale climate interventions to lower the earth's temperature, either by blocking incoming sunlight or removing carbon dioxide from the biosphere. Regarded as ‘technofixes’ by critics, these strategies have evoked concern that they would extend the shelf life of fossil-fuel driven socio-ecological systems for far longer than they otherwise would, or should, endure. A critical reading views geoengineering as a class project that is designed to keep the climate system stable enough for existing production systems to continue operating. This article first examines these concerns, and then goes on to envision a regime driven by humanitarian agendas and concern for vulnerable populations, implemented through international development and aid institutions. The motivations of those who fund research and implement geoengineering techniques are important, as the rationale for developing geoengineering strategies will determine which techniques are pursued, and hence which ecologies are produced. The logic that shapes the geoengineering research process could potentially influence social ecologies centuries from now.

  16. SOLAS Science and the Environmental Impacts of Geoengineering

    NASA Astrophysics Data System (ADS)

    Boyd, P.; Law, C. S.

    2016-02-01

    SOLAS (Surface Ocean Lower Atmosphere Study) has played a major role in establishing the elemental and ecosystem responses in the in situ mesoscale iron addition experiments. The outcomes of these experiments have included a Summary for Policymakers and an amendment on ocean fertilisation in the London Convention on marine dumping, which have informed both the debate and international regulation on this potential geoengineering approach. As part of Future Earth the next ten years of SOLAS Science will develop understanding and fundamental science in 5 major themes, including Greenhouse Gases and the Ocean, Interconnections between Aerosol, Clouds and Ecosystems, and Ocean Biogeochemical Controls on Atmospheric Chemistry. This poster will review the SOLAS science areas that provide fundamental knowledge on processes and ecosystem impacts, which is required for the robust assessment of potential Solar Radiation Management and Carbon Dioxide Removal techniques.

  17. Solar Geoengineering: Questioning the 'Winners and Losers' Paradigm (Invited)

    NASA Astrophysics Data System (ADS)

    Ricke, K.

    2013-12-01

    Concerns that greenhouse gas emissions reductions could be 'too little, too late' have led to increased dialogue within the scientific community regarding potential strategies for counteracting global warming through solar geoengineering - approaches which aim to counteract the effects of global warning by deflecting sunlight to space. Such approaches seek to reduce the amount of climate damage by intentional intervention in the climate system rather than by eliminating the inadvertent intervention causing the damage in the first place. Counteracting greenhouse gas-driven warming by blocking sunlight inevitably results in heterogeneous regional effects and one critique of solar geoengineering technologies is the supposed production of 'winners and losers.' It has become something of a meme to assert that any solar geoengineering deployment would result in 'winners' and 'losers'. However, the evidence underlying this assertion is weak. If Earth's climate system functions as represented in the current generation of climate models, at some level of solar geoengineering, everybody could be a 'winner'. If the models systematically fail to predict highly adverse, yet unanticipated, outcomes, then everybody could be a 'loser' In this talk, I will examine modeling studies analyzing the heterogeneous regional effects of solar geoengineering, presenting data from previously published studies reanalyzed in the context of what it means to 'win' or 'lose' when solar geoengineering is implemented. In particular, I will examine question of appropriate baselines for analysis and the importance of strategic versus absolute gains from implementation. I will conclude by proposing some more critical shortcomings of solar geoengineering than the 'winners and losers' problem and suggest how these shortcomings tie into other 'cutting-edge challenges in climate change science.'

  18. Efficient Formation of Stratospheric Aerosol for Climate Engineering by Emission of Condensible Vapor from Aircraft

    NASA Technical Reports Server (NTRS)

    Pierce, Jeffrey R.; Weisenstein, Debra K.; Heckendorn, Patricia; Peter. Thomas; Keith, David W.

    2010-01-01

    Recent analysis suggests that the effectiveness of stratospheric aerosol climate engineering through emission of non-condensable vapors such as SO2 is limited because the slow conversion to H2SO4 tends to produce aerosol particles that are too large; SO2 injection may be so inefficient that it is difficult to counteract the radiative forcing due to a CO2 doubling. Here we describe an alternate method in which aerosol is formed rapidly in the plume following injection of H2SO4, a condensable vapor, from an aircraft. This method gives better control of particle size and can produce larger radiative forcing with lower sulfur loadings than SO2 injection. Relative to SO2 injection, it may reduce some of the adverse effects of geoengineering such as radiative heating of the lower stratosphere. This method does not, however, alter the fact that such a geoengineered radiative forcing can, at best, only partially compensate for the climate changes produced by CO2.

  19. Regional Climate Variability Under Model Simulations of Solar Geoengineering

    NASA Astrophysics Data System (ADS)

    Dagon, Katherine; Schrag, Daniel P.

    2017-11-01

    Solar geoengineering has been shown in modeling studies to successfully mitigate global mean surface temperature changes from greenhouse warming. Changes in land surface hydrology are complicated by the direct effect of carbon dioxide (CO2) on vegetation, which alters the flux of water from the land surface to the atmosphere. Here we investigate changes in boreal summer climate variability under solar geoengineering using multiple ensembles of model simulations. We find that spatially uniform solar geoengineering creates a strong meridional gradient in the Northern Hemisphere temperature response, with less consistent patterns in precipitation, evapotranspiration, and soil moisture. Using regional summertime temperature and precipitation results across 31-member ensembles, we show a decrease in the frequency of heat waves and consecutive dry days under solar geoengineering relative to a high-CO2 world. However in some regions solar geoengineering of this amount does not completely reduce summer heat extremes relative to present day climate. In western Russia and Siberia, an increase in heat waves is connected to a decrease in surface soil moisture that favors persistent high temperatures. Heat waves decrease in the central United States and the Sahel, while the hydrologic response increases terrestrial water storage. Regional changes in soil moisture exhibit trends over time as the model adjusts to solar geoengineering, particularly in Siberia and the Sahel, leading to robust shifts in climate variance. These results suggest potential benefits and complications of large-scale uniform climate intervention schemes.

  20. Solar geoengineering, atmospheric water vapor transport, and land plants

    NASA Astrophysics Data System (ADS)

    Caldeira, Ken; Cao, Long

    2015-04-01

    This work, using the GeoMIP database supplemented by additional simulations, discusses how solar geoengineering, as projected by the climate models, affects temperature and the hydrological cycle, and how this in turn is related to projected changes in net primary productivity (NPP). Solar geoengineering simulations typically exhibit reduced precipitation. Solar geoengineering reduces precipitation because solar geoengineering reduces evaporation. Evaporation precedes precipitation, and, globally, evaporation equals precipitation. CO2 tends to reduce evaporation through two main mechanisms: (1) CO2 tends to stabilize the atmosphere especially over the ocean, leading to a moister atmospheric boundary layer over the ocean. This moistening of the boundary layer suppresses evaporation. (2) CO2 tends to diminish evapotranspiration, at least in most land-surface models, because higher atmospheric CO2 concentrations allow leaves to close their stomata and avoid water loss. In most high-CO2 simulations, these effects of CO2 which tend to suppress evaporation are masked by the tendency of CO2-warming effect to increase evaporation. In a geoengineering simulation, with the warming effect of CO2 largely offset by the solar geoengineering, the evaporation suppressing characteristics of CO2 are no longer masked and are clearly exhibited. Decreased precipitation in solar geoengineering simulations is a bit like ocean acidification - an effect of high CO2 concentrations that is not offset by solar geoengineering. Locally, precipitation ultimately either evaporates (much of that through the leaves of plants) or runs off through groundwater to streams and rivers. On long time scales, runoff equals precipitation minus evaporation, and thus, water runoff generated at a location is equal to the net atmospheric transport of water to that location. Runoff typically occurs where there is substantial soil moisture, at least seasonally. Locations where there is enough water to maintain

  1. Effects of geoengineering on crop yields

    NASA Astrophysics Data System (ADS)

    Pongratz, J.; Lobell, D. B.; Cao, L.; Caldeira, K.

    2011-12-01

    The potential of "solar radiation management" (SRM) to reduce future climate change and associated risks has been receiving significant attention in scientific and policy circles. SRM schemes aim to reduce global warming despite increasing atmospheric CO2 concentrations by diminishing the amount of solar insolation absorbed by the Earth, for example, by injecting scattering aerosols into the atmosphere. Climate models predict that SRM could fully compensate warming at the global mean in a high-CO2 world. While reduction of global warming may offset a part of the predicted negative effects of future climate change on crop yields, SRM schemes are expected to alter regional climate and to have substantial effects on climate variables other than temperature, such as precipitation. It has therefore been warned that, overall, SRM may pose a risk to food security. Assessments of benefits and risks of geoengineering are imperative, yet such assessments are only beginning to emerge; in particular, effects on global food security have not previously been assessed. Here, for the first time, we combine climate model simulations with models of crop yield responses to climate to assess large-scale changes in yields and food production under SRM. In most crop-growing regions, we find that yield losses caused by climate changes are substantially reduced under SRM as compared with a non-geoengineered doubling of atmospheric CO2. Substantial yield losses with SRM are only found for rice in high latitudes, where the limits of low temperatures are no longer alleviated. At the same time, the beneficial effect of CO2-fertilization on plant productivity remains active. Overall therefore, SRM in our models causes global crop yields to increase. We estimate the direct effects of climate and CO2 changes on crop production, and do not quantify effects of market dynamics and management changes. We note, however, that an SRM deployment would be unlikely to maintain the economic status quo, as

  2. Effects of Solar Geoengineering on Vegetation: Implications for Biodiversity and Conservation

    NASA Astrophysics Data System (ADS)

    Dagon, K.; Schrag, D. P.

    2017-12-01

    Climate change will have significant impacts on vegetation and biodiversity. Solar geoengineering has potential to reduce the climate effects of greenhouse gas emissions through albedo modification, yet more research is needed to better understand how these techniques might impact terrestrial ecosystems. Here we utilize the fully coupled version of the Community Earth System Model to run transient solar geoengineering simulations designed to stabilize radiative forcing starting mid-century, relative to the Representative Concentration Pathway 6 (RCP6) scenario. Using results from 100-year simulations, we analyze model output through the lens of ecosystem-relevant metrics. We find that solar geoengineering improves the conservation outlook under climate change, but there are still potential impacts on biodiversity. Two commonly used climate classification systems show shifts in vegetation under solar geoengineering relative to RCP6, though we acknowledge the associated uncertainties with these systems. We also show that rates of warming and the climate velocity are minimized globally under solar geoengineering by the end of the century, while trends persist over land in the Northern Hemisphere. Shifts in the amplitude of temperature and precipitation seasonal cycles are observed in the results, and have implications for vegetation phenology. Different metrics for vegetation productivity also show decreases under solar geoengineering relative to RCP6, but could be related to the model parameterization of nutrient cycling. Vegetation water cycling is found to be an important mechanism for understanding changes in ecosystems under solar geoengineering.

  3. Towards a comprehensive climate impacts assessment of solar geoengineering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Irvine, Peter J.; Kravitz, Ben; Lawrence, Mark G.

    Here, despite a growing literature on the projected physical climate responses to solar geoengineering — i.e. proposals to cool the planet by increasing the planetary albedo — there is no clear picture of the subsequent impacts of such a modified climate on natural and human systems such as agriculture, health, water resources, and ecosystems. Here we argue that engaging the climate impacts research community is necessary to evaluate and communicate how solar geoengineering might reduce some risks, exacerbate others, and give rise to novel risks. We review the current state of knowledge on consequences of solar geoengineering and conclude thatmore » a thorough assessment of its impacts can proceed by building upon the frameworks developed for assessing impacts of climate change. However, the climate response to solar geoengineering will depend on the form under consideration and the manner in which it is deployed, presenting a novel challenge for the climate impacts research community.« less

  4. Towards a comprehensive climate impacts assessment of solar geoengineering

    DOE PAGES

    Irvine, Peter J.; Kravitz, Ben; Lawrence, Mark G.; ...

    2016-11-23

    Here, despite a growing literature on the projected physical climate responses to solar geoengineering — i.e. proposals to cool the planet by increasing the planetary albedo — there is no clear picture of the subsequent impacts of such a modified climate on natural and human systems such as agriculture, health, water resources, and ecosystems. Here we argue that engaging the climate impacts research community is necessary to evaluate and communicate how solar geoengineering might reduce some risks, exacerbate others, and give rise to novel risks. We review the current state of knowledge on consequences of solar geoengineering and conclude thatmore » a thorough assessment of its impacts can proceed by building upon the frameworks developed for assessing impacts of climate change. However, the climate response to solar geoengineering will depend on the form under consideration and the manner in which it is deployed, presenting a novel challenge for the climate impacts research community.« less

  5. Additional risk of end-of-the-pipe geoengineering technologies

    NASA Astrophysics Data System (ADS)

    Bohle, Martin

    2014-05-01

    Humans are engineers, even the artists who engineer the surface of the globe. Should humans endeavour to engineer the Earth to counter climate change hazards? Striving towards 'global sustainability' will require to adjust the current production and consumption patterns. Contrary to an approach of global sustainability, 'geoengineering' deploys a 'technology fix' for the same purpose. Humans are much inclined to look for technological fixes for problems because well engineered technological methods have created modern societies. Thus, it seems obvious to apply an engineering solution to climate change issues too. In particular, as air pollution causing acid rains has been reduced by cleaner combustion processes or ozone destructing chemical coolants have been replaced by other substances. Common to these approaches was to reduce inputs into global or regional systems by withholding emission, replacing substances or limiting use cases for certain substances. Thus, the selected approach was a technological fix or regulatory measure targeting the 'start of the pipe'. However applying a 'start of the pipe' approach to climate change faces the issue that mankind should reduce inputs were its hurts, namely reducing radically energy that is produced from burning fossil fuels. Capping burning of fossil fuels would be disruptive for the economic structures or the consumption pattern of the developed and developing industrialised societies. Facing that dilemma, affordable geoengineering looks tempting for some. However geoengineering technologies, which counter climate change by other means than carbon capture at combustion, are of a different nature than the technological fixes and negotiated regulatory actions, which so far have been applied to limit threats to regional and global systems. Most of the proposed technologies target other parts of the climate system but the carbon-dioxide input into the atmosphere. Therefore, many geoengineering technologies differ

  6. Potential negative consequences of geoengineering on crop production: A study of Indian groundnut.

    PubMed

    Yang, Huiyi; Dobbie, Steven; Ramirez-Villegas, Julian; Feng, Kuishuang; Challinor, Andrew J; Chen, Bing; Gao, Yao; Lee, Lindsay; Yin, Yan; Sun, Laixiang; Watson, James; Koehler, Ann-Kristin; Fan, Tingting; Ghosh, Sat

    2016-11-28

    Geoengineering has been proposed to stabilize global temperature, but its impacts on crop production and stability are not fully understood. A few case studies suggest that certain crops are likely to benefit from solar dimming geoengineering, yet we show that geoengineering is projected to have detrimental effects for groundnut. Using an ensemble of crop-climate model simulations, we illustrate that groundnut yields in India undergo a statistically significant decrease of up to 20% as a result of solar dimming geoengineering relative to RCP4.5. It is somewhat reassuring, however, to find that after a sustained period of 50 years of geoengineering crop yields return to the nongeoengineered values within a few years once the intervention is ceased.

  7. Potential negative consequences of geoengineering on crop production: A study of Indian groundnut

    NASA Astrophysics Data System (ADS)

    Yang, Huiyi; Dobbie, Steven; Ramirez-Villegas, Julian; Feng, Kuishuang; Challinor, Andrew J.; Chen, Bing; Gao, Yao; Lee, Lindsay; Yin, Yan; Sun, Laixiang; Watson, James; Koehler, Ann-Kristin; Fan, Tingting; Ghosh, Sat

    2016-11-01

    Geoengineering has been proposed to stabilize global temperature, but its impacts on crop production and stability are not fully understood. A few case studies suggest that certain crops are likely to benefit from solar dimming geoengineering, yet we show that geoengineering is projected to have detrimental effects for groundnut. Using an ensemble of crop-climate model simulations, we illustrate that groundnut yields in India undergo a statistically significant decrease of up to 20% as a result of solar dimming geoengineering relative to RCP4.5. It is somewhat reassuring, however, to find that after a sustained period of 50 years of geoengineering crop yields return to the nongeoengineered values within a few years once the intervention is ceased.

  8. No fudging on geoengineering

    NASA Astrophysics Data System (ADS)

    Parker, Andy; Geden, Oliver

    2016-12-01

    The Intergovernmental Panel on Climate Change is preparing a report on keeping global warming below 1.5 °C. How the panel chooses to deal with the option of solar geoengineering will test the integrity of scientific climate policy advice.

  9. Climate impacts of geoengineering in a delayed mitigation scenario

    NASA Astrophysics Data System (ADS)

    Tilmes, S.; Sanderson, B. M.; O'Neill, B. C.

    2016-08-01

    Decarbonization in the immediate future is required to limit global mean temperature (GMT) increase to 2°C relative to preindustrial conditions, if geoengineering is not considered. Here we use the Community Earth System Model (CESM) to investigate climate outcomes if no mitigation is undertaken until GMT has reached 2°C. We find that late decarbonization in CESM without applying stratospheric sulfur injection (SSI) leads to a peak temperature increase of 3°C and GMT remains above 2° for 160 years. An additional gradual increase and then decrease of SSI over this period reaching about 1.5 times the aerosol burden resulting from the Mount Pinatubo eruption in 1992 would limit the increase in GMT to 2.0° for the specific pathway and model. SSI produces mean and extreme temperatures in CESM comparable to an early decarbonization pathway, but aridity is not mitigated to the same extent.

  10. Potential negative consequences of geoengineering on crop production: A study of Indian groundnut

    PubMed Central

    Dobbie, Steven; Ramirez‐Villegas, Julian; Feng, Kuishuang; Challinor, Andrew J.; Chen, Bing; Gao, Yao; Lee, Lindsay; Yin, Yan; Sun, Laixiang; Watson, James; Koehler, Ann‐Kristin; Fan, Tingting; Ghosh, Sat

    2016-01-01

    Abstract Geoengineering has been proposed to stabilize global temperature, but its impacts on crop production and stability are not fully understood. A few case studies suggest that certain crops are likely to benefit from solar dimming geoengineering, yet we show that geoengineering is projected to have detrimental effects for groundnut. Using an ensemble of crop‐climate model simulations, we illustrate that groundnut yields in India undergo a statistically significant decrease of up to 20% as a result of solar dimming geoengineering relative to RCP4.5. It is somewhat reassuring, however, to find that after a sustained period of 50 years of geoengineering crop yields return to the nongeoengineered values within a few years once the intervention is ceased. PMID:28190903

  11. Impacts of Stratospheric Sulfate Geoengineering on Chinese Agricultural Production

    NASA Astrophysics Data System (ADS)

    Xia, L.; Robock, A.

    2012-12-01

    Possible food supply change is one of the most important concerns in the discussion of stratospheric sulfate geoengineering. In China, the high population density and strong summer monsoon influence on agriculture make this region sensitive to climate changes, such as reductions of precipitation, temperature, and solar radiation spurred by stratospheric sulfate injection. We used results from the Geoengineering Model Intercomparison Project G2 scenario to force the Decision Support System for Agrotechnology Transfer (DSSAT) crop model to predict crop yield changes from rice, maize, and winter wheat. We first evaluated the DSSAT model by forcing it with daily observed weather data and management practices for the period 1978-2008 for all the provinces in China, and compared the results to observations of the yields of the three major crops in China. We then created two 50-year sets of climate anomalies using the results from eight climate models, for 1%/year increase of CO2 and for G2 (1%/year increase of CO2 balanced by insolation reduction), and compared the resulting agricultural responses. Considering that geoengineering could happen in the future, we used two geoengineering starting years, 2020 and 2060. For 2020, we increased the mean temperature by 1°C and started the CO2 concentration at 410 ppm. For 2060, we increased temperature by 2°C and started the CO2 concentration at 550 ppm. Without changing agriculture technology, we find that compared to the control run, geoengineering with the G2 scenario starting in 2020 or 2060 would both moderately increase rice and winter wheat production due to the CO2 fertilization effect, but the increasing rates are different. However, as a C4 crop, without a significant CO2 fertilization effect, maize production would decrease slightly because of regional drought. Compared to the reference run, the three crops all have less heat stress in southern China and their yields increase, but in northern China cooler

  12. Simulated Effect of Carbon Cycle Feedback on Climate Response to Solar Geoengineering

    NASA Astrophysics Data System (ADS)

    Cao, Long; Jiang, Jiu

    2017-12-01

    Most modeling studies investigate climate effects of solar geoengineering under prescribed atmospheric CO2, thereby neglecting potential climate feedbacks from the carbon cycle. Here we use an Earth system model to investigate interactive feedbacks between solar geoengineering, global carbon cycle, and climate change. We design idealized sunshade geoengineering simulations to prevent global warming from exceeding 2°C above preindustrial under a CO2 emission scenario with emission mitigation starting from middle of century. By year 2100, solar geoengineering reduces the burden of atmospheric CO2 by 47 PgC with enhanced carbon storage in the terrestrial biosphere. As a result of reduced atmospheric CO2, consideration of the carbon cycle feedback reduces required insolation reduction in 2100 from 2.0 to 1.7 W m-2. With higher climate sensitivity the effect from carbon cycle feedback becomes more important. Our study demonstrates the importance of carbon cycle feedback in climate response to solar geoengineering.

  13. Climate Impacts of Geoengineering in a Delayed Mitigation Scenario

    NASA Astrophysics Data System (ADS)

    Tilmes, S.; Sanderson, B. M.; O'Neill, B. C.

    2016-12-01

    Decarbonization in the immediate future is required to limit global mean temperature (GMT) increase to 2 degrees C relative to pre-industrial conditions, if geoengineering is not considered. Here we use the Community Earth System Model (CESM) to investigate climate outcomes if no mitigation is undertaken until GMT has reached 2 degree C. We find that late decarbonization (LD) in CESM without applying stratospheric sulfur injection (SSI) leads to a peak temperature increase of 3 degree C and GMT remains above 2 degrees for 160 years. An additional gradual increase and then decrease of SSI over this period reaching about 1.5 times the aerosol burden resulting from the Mt Pinatubo eruption in 1992 would limit the increase in GMT to 2.0 degrees for the specific pathway and model. SSI produces mean and extreme temperatures in CESM comparable to an early decarbonization pathway, but aridity is not mitigated to the same extent.

  14. The Risk of Termination Shock From Solar Geoengineering

    NASA Astrophysics Data System (ADS)

    Parker, Andy; Irvine, Peter J.

    2018-03-01

    If solar geoengineering were to be deployed so as to mask a high level of global warming, and then stopped suddenly, there would be a rapid and damaging rise in temperatures. This effect is often referred to as termination shock, and it is an influential concept. Based on studies of its potential impacts, commentators often cite termination shock as one of the greatest risks of solar geoengineering. However, there has been little consideration of the likelihood of termination shock, so that conclusions about its risk are premature. This paper explores the physical characteristics of termination shock, then uses simple scenario analysis to plot out the pathways by which different driver events (such as terrorist attacks, natural disasters, or political action) could lead to termination. It then considers where timely policies could intervene to avert termination shock. We conclude that some relatively simple policies could protect a solar geoengineering system against most of the plausible drivers. If backup deployment hardware were maintained and if solar geoengineering were implemented by agreement among just a few powerful countries, then the system should be resilient against all but the most extreme catastrophes. If this analysis is correct, then termination shock should be much less likely, and therefore much less of a risk, than has previously been assumed. Much more sophisticated scenario analysis—going beyond simulations purely of worst-case scenarios—will be needed to allow for more insightful policy conclusions.

  15. Geoengineering, climate change scepticism and the 'moral hazard' argument: an experimental study of UK public perceptions.

    PubMed

    Corner, Adam; Pidgeon, Nick

    2014-12-28

    Many commentators have expressed concerns that researching and/or developing geoengineering technologies may undermine support for existing climate policies-the so-called moral hazard argument. This argument plays a central role in policy debates about geoengineering. However, there has not yet been a systematic investigation of how members of the public view the moral hazard argument, or whether it impacts on people's beliefs about geoengineering and climate change. In this paper, we describe an online experiment with a representative sample of the UK public, in which participants read one of two arguments (either endorsing or rejecting the idea that geoengineering poses a moral hazard). The argument endorsing the idea of geoengineering as a moral hazard was perceived as more convincing overall. However, people with more sceptical views and those who endorsed 'self-enhancing' values were more likely to agree that the prospect of geoengineering would reduce their motivation to make changes in their own behaviour in response to climate change. The findings suggest that geoengineering is likely to pose a moral hazard for some people more than others, and the implications for engaging the public are discussed.

  16. Modeling the Climatic Consequences of Geoengineering

    NASA Astrophysics Data System (ADS)

    Somerville, R. C.

    2005-12-01

    The last half-century has seen the development of physically comprehensive computer models of the climate system. These models are the primary tool for making predictions of climate change due to human activities, such as emitting greenhouse gases into the atmosphere. Because scientific understanding of the climate system is incomplete, however, any climate model will necessarily have imperfections. The inevitable uncertainties associated with these models have sometimes been cited as reasons for not taking action to reduce such emissions. Climate models could certainly be employed to predict the results of various attempts at geoengineering, but many questions would arise. For example, in considering proposals to increase the planetary reflectivity by brightening parts of the land surface or by orbiting mirrors, can models be used to bound the results and to warm of unintended consequences? How could confidence limits be placed on such model results? How can climate changes due to proposed geoengineering be distinguished from natural variability? There are historical parallels on smaller scales, in which models have been employed to predict the results of attempts to alter the weather, such as the use of cloud seeding for precipitation enhancement, hail suppression and hurricane modification. However, there are also many lessons to be learned from the recent record of using models to simulate the effects of the great unintended geoengineering experiment involving greenhouse gases, now in progress. In this major research effort, the same types of questions have been studied at length. The best modern models have demonstrated an impressive ability to predict some aspects of climate change. A large body of evidence has already accumulated through comparing model predictions to many observed aspects of recent climate change, ranging from increases in ocean heat content to changes in atmospheric water vapor to reductions in glacier extent. The preponderance of expert

  17. Geoengineering, climate change scepticism and the ‘moral hazard’ argument: an experimental study of UK public perceptions

    PubMed Central

    Corner, Adam; Pidgeon, Nick

    2014-01-01

    Many commentators have expressed concerns that researching and/or developing geoengineering technologies may undermine support for existing climate policies—the so-called moral hazard argument. This argument plays a central role in policy debates about geoengineering. However, there has not yet been a systematic investigation of how members of the public view the moral hazard argument, or whether it impacts on people's beliefs about geoengineering and climate change. In this paper, we describe an online experiment with a representative sample of the UK public, in which participants read one of two arguments (either endorsing or rejecting the idea that geoengineering poses a moral hazard). The argument endorsing the idea of geoengineering as a moral hazard was perceived as more convincing overall. However, people with more sceptical views and those who endorsed ‘self-enhancing’ values were more likely to agree that the prospect of geoengineering would reduce their motivation to make changes in their own behaviour in response to climate change. The findings suggest that geoengineering is likely to pose a moral hazard for some people more than others, and the implications for engaging the public are discussed. PMID:25404680

  18. Geoengineering the climate

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    MacCracken, M.C.

    1991-06-18

    Although much can be done to limit greenhouse gas emissions by conservation, improvements in efficiency, and use of alternative technologies, the use of fossil fuels at rates even sharply reduced from US per capita values will lead to rapidly increasing global concentrations of greenhouse gases. The available alternatives then become adapting to the changes, switching to alternative energy sources (e.g., solar, nuclear), or actively taking control of atmospheric composition and/or the climate. This note reviews options for geoengineering the climate. 18 refs., 1 tab.

  19. Constraining Upper Troposphere/Lower Stratosphere Aerosol Physical Processes with High-Altitude Aircraft Measurements

    NASA Technical Reports Server (NTRS)

    Jensen, Eric; Rosenlof, Karen H.; Thornberry, Troy

    2018-01-01

    Interest in a more complete understanding of the sources, composition and microphysics of stratospheric aerosol particles has intensified during recent years for several reasons: (1) small volcanic eruptions have been recognized as a driver of short-term changes in climate forcing; (2) emissions of sulfur dioxide (SO2) and other aerosol precursors have shifted to south Asia and other low latitude regions with intense vertical transport; (3) organic material has been recognized as a key contributor to lower stratospheric aerosol mass; and (4) interest in possible solar radiation management (geoengineering) through significant enhancements in stratospheric aerosols has intensified. To address stratospheric aerosol science issues, we are proposing a NASA Earth Ventures mission to NASA to provide extensive high-altitude aircraft measurements of critical gas-phase and aerosol properties at multiple locations across the planet. In this presentation, we will discuss the objectives of the proposed campaign, the measurements provided, the sampling strategy, and the modeling and analysis approaches that would be used to address specific science questions.

  20. Quantifying the equilibrium partitioning of substituted polycyclic aromatic hydrocarbons in aerosols and clouds using COSMOtherm.

    PubMed

    Awonaike, Boluwatife; Wang, Chen; Goss, Kai-Uwe; Wania, Frank

    2017-03-22

    Functional groups attached to polycyclic aromatic hydrocarbons (PAHs) can significantly modify the environmental fate of the parent compound. Equilibrium partition coefficients, which are essential for describing the environmental phase distribution of a compound, are largely unavailable for substituted PAHs (SPAHs). Here, COSMOtherm, a software based on quantum-chemical calculations is used to estimate the atmospherically relevant partition coefficients between the gas phase, the aqueous bulk phase, the water surface and the water insoluble organic matter phase, as well as the salting-out coefficients, for naphthalene, anthracene, phenanthrene, benz(a)anthracene, benzo(a)pyrene and dibenz(a,h)anthracene and 62 of their substituted counterparts. They serve as input parameters for the calculation of equilibrium phase distribution of these compounds in aerosols and clouds. Our results, which were compared with available experimental data, show that the effect of salts, the adsorption to the water surface and the dissolution in a bulk aqueous phase can be safely neglected when estimating the gas-particle partitioning of SPAHs in aerosols. However, for small PAHs with more than one polar functional group the aqueous phase can be the dominant reservoir in a cloud.

  1. Geoengineering the Climate: Approaches to Counterbalancing Global Warming

    NASA Astrophysics Data System (ADS)

    MacCracken, M. C.

    2005-12-01

    For the past two hundred years, the inadvertent release of carbon dioxide and other radiatively active gases and aerosols, particularly as a result of combustion of fossil fuels and changes in land cover, have been contributing to global climate change. Global warming to date is approaching 1°C, and this is being accompanied by reduced sea ice, rising sea level, shifting ecosystems and more. Rather than sharply curtailing use of fossil fuels in order to reduce CO2 emissions and eventually eliminate the net human influence on global climate, a number of approaches have been suggested that are intended to advertently modify the climate in a manner to counter-balance the warming influence of greenhouse gas emissions. One general type of approach is carbon sequestration, which focuses on capturing the CO2 and then sequestering it underground or in the ocean. This can be done at the source of emission, by pulling the CO2 out of the atmosphere through some chemical process, or by enhancing the natural processes that remove CO2 from the atmosphere, for example by fertilizing the oceans with iron. A second general approach to geoengineering the climate is to lower the warming influence of the incoming solar radiation by an amount equivalent to the energy captured by the CO2-induced enhancement of the greenhouse effect. Proposals have been made to do this by locating a deflector at the Earth-Sun Lagrange point, lofting many thousands of near-Earth mirrors, injecting aerosols into the stratosphere, or by increasing the surface albedo. A third general approach is to alter natural Earth system processes in ways that would counterbalance the effects of the warming. Among suggested approaches are constructing dams to block various ocean passages, oceanic films to limit evaporation and water vapor feedback, and even, at small scale, to insulate mountain glaciers to prevent melting. Each of these approaches has its advantages, ranging from simplicity to reversibility, and

  2. Solar Geoengineering as part of an overall strategy for meeting the 1.5C Paris target

    NASA Astrophysics Data System (ADS)

    Ricke, K.; MacMartin, D. G.; Keith, D.

    2017-12-01

    If future mitigation proves insufficient to limit the rise in global mean temperature to less than 1.5C above preindustrial, it is plausible that some additional and limited deployment of solar geoengineering could reduce climate damages. That is, these approaches could eventually be considered as part of an overall strategy to manage the risks of climate change, combining emissions reduction, net-negative emissions technologies, and solar geoengineering to meet climate goals. Since few climate model simulations have considered these limited deployment scenarios, we use a climate emulator trained from GeoMIP output to assess the projected response if solar geoengineering were used to limit global mean temperature to 1.5C above preindustrial in an overshoot scenario that would otherwise peak near 3C. The resulting climate is much closer in many respects to a climate where the 1.5C target is achieved through mitigation alone than either is to the 3C climate with no geoengineering, although there are some important differences. In this limited deployment scenario, there is no "over-compensation" of global-mean precipitation changes, nor are there any regions where a majority of models project that the use of geoengineering would lead to a statistically-significant change in precipitation further away from preindustrial than would have occurred without using geoengineering. This highlights the importance of evaluating geoengineering impacts in the context of specific policy-relevant scenarios.

  3. Constraining the long-term climate reponse to stratospheric sulfate aerosols injection by the short-term volcanic climate response

    NASA Astrophysics Data System (ADS)

    Plazzotta, M.; Seferian, R.; Douville, H.; Kravitz, B.; Tilmes, S.; Tjiputra, J.

    2016-12-01

    Rising greenhouse gas emissions are leading to global warming and climate change, which will have multiple impacts on human society. Geoengineering methods like solar radiation management by stratospheric sulfate aerosols injection (SSA-SRM) aim at treating the symptoms of climate change by reducing the global temperature. Since a real-world testing cannot be implemented, Earth System Models (ESMs) are useful tools to assess the climate impacts of such geoengineering methods. However, coordinated simulations performed with the Geoengineering Model Intercomparison Project (GeoMIP) have shown that climate cooling in response to a continuous injection of 5Tg of SO2 per year under RCP45 future projection (the so-called G4 experiment) differs substantially between ESMs. Here, we employ a volcano analog approach to constrain the climate response in SSA-SRM geoengineering simulations across an ensemble of 10 ESMs. We identify an emergent relationship between the long-term cooling in responses to the mitigation of the clear-sky surface downwelling shortwave radiation (RSDSCS), and the short-term cooling related to the change in RSDSCS during the major tropical volcanic eruptions observed over the historical period (1850-2005). This relationship explains almost 80% of the multi-model spread. Combined with contemporary observations of the latest volcanic eruptions (satellite observations and model reanalyzes), this relationship provides a tight constraint on the climate impacts of SSA-SRM. We estimate that a continuous injection of SO2 aerosols into the stratosphere will reduce the global average temperature of continental land surface by 0.47 K per W m-2, impacting both hydrological and carbon cycles. Compared with the unconstrained ESMs ensemble (range from 0.32 to 0.92 K per W m-2 ), our estimate represents much higher confidence ways to assess the impacts of SSA-SRM on the climate while ruling the most extreme projections of the unconstrained ensemble extremely unlikely.

  4. Unintended consequences of atmospheric injection of sulphate aerosols.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brady, Patrick Vane; Kobos, Peter Holmes; Goldstein, Barry

    2010-10-01

    Most climate scientists believe that climate geoengineering is best considered as a potential complement to the mitigation of CO{sub 2} emissions, rather than as an alternative to it. Strong mitigation could achieve the equivalent of up to -4Wm{sup -2} radiative forcing on the century timescale, relative to a worst case scenario for rising CO{sub 2}. However, to tackle the remaining 3Wm{sup -2}, which are likely even in a best case scenario of strongly mitigated CO{sub 2} releases, a number of geoengineering options show promise. Injecting stratospheric aerosols is one of the least expensive and, potentially, most effective approaches and formore » that reason an examination of the possible unintended consequences of the implementation of atmospheric injections of sulphate aerosols was made. Chief among these are: reductions in rainfall, slowing of atmospheric ozone rebound, and differential changes in weather patterns. At the same time, there will be an increase in plant productivity. Lastly, because atmospheric sulphate injection would not mitigate ocean acidification, another side effect of fossil fuel burning, it would provide only a partial solution. Future research should aim at ameliorating the possible negative unintended consequences of atmospheric injections of sulphate injection. This might include modeling the optimum rate and particle type and size of aerosol injection, as well as the latitudinal, longitudinal and altitude of injection sites, to balance radiative forcing to decrease negative regional impacts. Similarly, future research might include modeling the optimum rate of decrease and location of injection sites to be closed to reduce or slow rapid warming upon aerosol injection cessation. A fruitful area for future research might be system modeling to enhance the possible positive increases in agricultural productivity. All such modeling must be supported by data collection and laboratory and field testing to enable iterative modeling to

  5. Biogeochemical carbon coupling influences global precipitation in geoengineering experiments

    NASA Astrophysics Data System (ADS)

    Fyfe, J. C.; Cole, J. N. S.; Arora, V. K.; Scinocca, J. F.

    2013-02-01

    Abstract Climate model studies in which CO2-induced global warming is offset by engineered decreases of incoming solar radiation are generally robust in their prediction of reduced amounts of global precipitation. While this precipitation response has been explained on the basis of changes in net radiation controlling evaporative processes at the surface, there has been relatively little consideration of the relative role of biogeochemical carbon-cycle interactions. To address this issue, we employ an Earth System Model that includes oceanic and terrestrial carbon components to isolate the impact of biogeochemical carbon coupling on the precipitation response in <span class="hlt">geoengineering</span> experiments for two types of solar radiation management. We show that carbon coupling is responsible for a large fraction of the global precipitation reduction in such <span class="hlt">geoengineering</span> experiments and that the primary effect comes from reduced transpiration through the leaves of plants and trees in the terrestrial component of the carbon cycle due to elevated CO2. Our results suggest that biogeochemical interactions are as important as changes in net radiation and that climate models that do not account for such carbon coupling may significantly underestimate precipitation reductions in a <span class="hlt">geoengineered</span> world.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..DFD.A1007S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..DFD.A1007S"><span>Experimental Characterization of Radiation Forcing due to Atmospheric <span class="hlt">Aerosols</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sreenivas, K. R.; Singh, D. K.; Ponnulakshmi, V. K.; Subramanian, G.</p> <p>2011-11-01</p> <p>Micro-meteorological processes in the nocturnal atmospheric boundary layer (NBL) including the formation of radiation-fog and the development of inversion layers are controlled by heat transfer and the vertical temperature distribution close to the ground. In a recent study, it has been shown that the temperature profile close to the ground in stably-stratified, NBL is controlled by the radiative forcing due to suspended <span class="hlt">aerosols</span>. Estimating <span class="hlt">aerosol</span> forcing is also important in <span class="hlt">geo-engineering</span> applications to evaluate the use of <span class="hlt">aerosols</span> to mitigate greenhouse effects. Modeling capability in the above scenarios is limited by our knowledge of this forcing. Here, the design of an experimental setup is presented which can be used for evaluating the IR-radiation forcing on <span class="hlt">aerosols</span> under either Rayleigh-Benard condition or under conditions corresponding to the NBL. We present results indicating the effect of surface emissivities of the top and bottom boundaries and the <span class="hlt">aerosol</span> concentration on the temperature profiles. In order to understand the observed enhancement of the convection-threshold, we have determined the conduction-radiation time constant of an <span class="hlt">aerosol</span> laden air layer. Our results help to explain observed temperature profiles in the NBL, the apparent stability of such profiles and indicate the need to account for the effect of <span class="hlt">aerosols</span> in climatic/weather models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGC33A1089X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGC33A1089X"><span>Impacts on Chinese Agriculture of <span class="hlt">Geoengineering</span> and Smoke from Fires Ignited by Nuclear War</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xia, L.; Robock, A.</p> <p>2013-12-01</p> <p>Climate is one of the most important factors determining crop yields and world food supplies. To be well prepared for possible futures, it is necessary to study yield changes of major crops under different climate scenarios. Here we consider two situations: stratospheric sulfate <span class="hlt">geoengineering</span> and nuclear war. Although we certainly do not advocate either scenario, we cannot exclude the possibilities: if global warming is getting worse, society might consider deliberately manipulating global temperature; if nuclear weapons still exist, we might face a nuclear war catastrophe. Since in both scenarios there would be reductions of temperature, precipitation, and insolation, which are three controlling factors on crop growth, it is important to study food supply changes under the two cases. We conducted our simulations for China, because it has the highest population and crop production in the world and it is under the strong influence of the summer monsoon, which would be altered in <span class="hlt">geoengineering</span> and nuclear war scenarios. To examine the effects of climate changes induced by <span class="hlt">geoengineering</span> and nuclear war on Chinese agriculture, we use the Decision Support System for Agrotechnology Transfer (DSSAT) crop model. We first evaluated the model by forcing it with daily weather data and management practices for the period 1978-2008 for 24 provinces in China, and compared the results to observations of the yields of major crops in China (middle season rice, winter wheat, and maize). Then we perturbed observed weather data using climate anomalies for <span class="hlt">geoengineering</span> and nuclear war simulations. For <span class="hlt">geoengineering</span>, we consider the G2 scenario of the <span class="hlt">Geoengineering</span> Model Intercomparison Project (GeoMIP), which prescribes an insolation reduction to balance a 1% per year increase in CO2 concentration (1pctCO2). We used results from ten climate models participating in G2. For the nuclear war scenario, we consider the effects of 5 Tg of soot that could be injected into the upper</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGC31I..06I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGC31I..06I"><span>Precipitation response to solar <span class="hlt">geoengineering</span> in a high-resolution tropical-cyclone permitting coupled general circulation model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Irvine, P. J.; Keith, D.; Dykema, J. A.; Vecchi, G. A.; Horowitz, L. W.</p> <p>2016-12-01</p> <p>Solar <span class="hlt">geoengineering</span> may limit or even halt the rise in global-average surface temperatures. Evidence from the geoMIP model intercomparison project shows that idealized <span class="hlt">geoengineering</span> can greatly reduce temperature changes on a region-by-region basis. If solar <span class="hlt">geoengineering</span> is used to hold radiative forcing or surface temperatures constant in the face of rising CO2, then the global evaporation and precipitation rates will be reduced below pre-industrial. The spartial and frequency distribution of the precipitation response is, however, much less well understood. There is limited evidence that solar <span class="hlt">geoengineering</span> may reduce extreme precipitation events more that it reduces mean precipitation, but that evidence is based on relatively course resolution models that may to a poor job representing the distribution of extreme precipitation in the current climate. The response of global and regional climate, as well as tropical cyclone (TC) activity, to increasing solar <span class="hlt">geoengineering</span> is explored through experiments with climate models spanning a broad range of atmospheric resolutions. Solar <span class="hlt">geoengineering</span> is represented by an idealized adjustment of the solar constant that roughly halves the rate of increase in radiative forcing in a scenario with increasing CO2 concentration. The coarsest resolution model has approximately a 2-degree global resolution, representative of the typical resolution of past GCMs used to explore global response to CO2 increase, and its response is compared to that of two tropical cyclone permitting GCMs of approximately 0.5 and 0.25 degree resolution (FLOR and HiFLOR). The models have exactly the same ocean and sea-ice components, as well as the same parameterizations and parameter settings. These high-resolution models are used for real-time seasonal prediction, providing a unified framework for seasonal-to-multidecadal climate modeling. We assess the extreme precipitation response, comparing the frequency distribution of extreme events with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5069533','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5069533"><span>Developing a test-bed for robust research governance of <span class="hlt">geoengineering</span>: the contribution of ocean iron biogeochemistry</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bressac, Matthieu</p> <p>2016-01-01</p> <p><span class="hlt">Geoengineering</span> to mitigate climate change has long been proposed, but remains nebulous. Exploration of the feasibility of <span class="hlt">geoengineering</span> first requires the development of research governance to move beyond the conceptual towards scientifically designed pilot studies. Fortuitously, 12 mesoscale (approx. 1000 km2) iron enrichments, funded to investigate how ocean iron biogeochemistry altered Earth's carbon cycle in the geological past, provide proxies to better understand the benefits and drawbacks of <span class="hlt">geoengineering</span>. The utility of these iron enrichments in the <span class="hlt">geoengineering</span> debate is enhanced by the GEOTRACES global survey. Here, we outline how GEOTRACES surveys and process studies can provide invaluable insights into <span class="hlt">geoengineering</span>. Surveys inform key unknowns including the regional influence and magnitude of modes of iron supply, and stimulate iron biogeochemical modelling. These advances will enable quantification of interannual variability of iron supply to assess whether any future purposeful multi-year iron-fertilization meets the principle of ‘additionality’ (sensu Kyoto protocol). Process studies address issues including upscaling of <span class="hlt">geoengineering</span>, and how differing iron-enrichment strategies could stimulate wide-ranging biogeochemical outcomes. In summary, the availability of databases on both mesoscale iron-enrichment studies and the GEOTRACES survey, along with modelling, policy initiatives and legislation have positioned the iron-enrichment approach as a robust multifaceted test-bed to assess proposed research into climate intervention. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’. PMID:29035263</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29035263','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29035263"><span>Developing a test-bed for robust research governance of <span class="hlt">geoengineering</span>: the contribution of ocean iron biogeochemistry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Boyd, Philip W; Bressac, Matthieu</p> <p>2016-11-28</p> <p><span class="hlt">Geoengineering</span> to mitigate climate change has long been proposed, but remains nebulous. Exploration of the feasibility of <span class="hlt">geoengineering</span> first requires the development of research governance to move beyond the conceptual towards scientifically designed pilot studies. Fortuitously, 12 mesoscale (approx. 1000 km 2 ) iron enrichments, funded to investigate how ocean iron biogeochemistry altered Earth's carbon cycle in the geological past, provide proxies to better understand the benefits and drawbacks of <span class="hlt">geoengineering</span>. The utility of these iron enrichments in the <span class="hlt">geoengineering</span> debate is enhanced by the GEOTRACES global survey. Here, we outline how GEOTRACES surveys and process studies can provide invaluable insights into <span class="hlt">geoengineering</span>. Surveys inform key unknowns including the regional influence and magnitude of modes of iron supply, and stimulate iron biogeochemical modelling. These advances will enable quantification of interannual variability of iron supply to assess whether any future purposeful multi-year iron-fertilization meets the principle of 'additionality' ( sensu Kyoto protocol). Process studies address issues including upscaling of <span class="hlt">geoengineering</span>, and how differing iron-enrichment strategies could stimulate wide-ranging biogeochemical outcomes. In summary, the availability of databases on both mesoscale iron-enrichment studies and the GEOTRACES survey, along with modelling, policy initiatives and legislation have positioned the iron-enrichment approach as a robust multifaceted test-bed to assess proposed research into climate intervention.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'. © 2016 The Author(s).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GMD....10.3359K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GMD....10.3359K"><span>The Sectional Stratospheric Sulfate <span class="hlt">Aerosol</span> module (S3A-v1) within the LMDZ general circulation model: description and evaluation against stratospheric <span class="hlt">aerosol</span> observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kleinschmitt, Christoph; Boucher, Olivier; Bekki, Slimane; Lott, François; Platt, Ulrich</p> <p>2017-09-01</p> <p>Stratospheric <span class="hlt">aerosols</span> play an important role in the climate system by affecting the Earth's radiative budget as well as atmospheric chemistry, and the capabilities to simulate them interactively within global models are continuously improving. It is important to represent accurately both <span class="hlt">aerosol</span> microphysical and atmospheric dynamical processes because together they affect the size distribution and the residence time of the <span class="hlt">aerosol</span> particles in the stratosphere. The newly developed LMDZ-S3A model presented in this article uses a sectional approach for sulfate particles in the stratosphere and includes the relevant microphysical processes. It allows full interaction between <span class="hlt">aerosol</span> radiative effects (e.g. radiative heating) and atmospheric dynamics, including e.g. an internally generated quasi-biennial oscillation (QBO) in the stratosphere. Sulfur chemistry is semi-prescribed via climatological lifetimes. LMDZ-S3A reasonably reproduces <span class="hlt">aerosol</span> observations in periods of low (background) and high (volcanic) stratospheric sulfate loading, but tends to overestimate the number of small particles and to underestimate the number of large particles. Thus, it may serve as a tool to study the climate impacts of volcanic eruptions, as well as the deliberate anthropogenic injection of <span class="hlt">aerosols</span> into the stratosphere, which has been proposed as a method of <span class="hlt">geoengineering</span> to abate global warming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25404677','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25404677"><span>Process-model simulations of cloud albedo enhancement by <span class="hlt">aerosols</span> in the Arctic.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kravitz, Ben; Wang, Hailong; Rasch, Philip J; Morrison, Hugh; Solomon, Amy B</p> <p>2014-12-28</p> <p>A cloud-resolving model is used to simulate the effectiveness of Arctic marine cloud brightening via injection of cloud condensation nuclei (CCN), either through <span class="hlt">geoengineering</span> or other increased sources of Arctic <span class="hlt">aerosols</span>. An updated cloud microphysical scheme is employed, with prognostic CCN and cloud particle numbers in both liquid and mixed-phase marine low clouds. Injection of CCN into the marine boundary layer can delay the collapse of the boundary layer and increase low-cloud albedo. Albedo increases are stronger for pure liquid clouds than mixed-phase clouds. Liquid precipitation can be suppressed by CCN injection, whereas ice precipitation (snow) is affected less; thus, the effectiveness of brightening mixed-phase clouds is lower than for liquid-only clouds. CCN injection into a clean regime results in a greater albedo increase than injection into a polluted regime, consistent with current knowledge about <span class="hlt">aerosol</span>-cloud interactions. Unlike previous studies investigating warm clouds, dynamical changes in circulation owing to precipitation changes are small. According to these results, which are dependent upon the representation of ice nucleation processes in the employed microphysical scheme, Arctic <span class="hlt">geoengineering</span> is unlikely to be effective as the sole means of altering the global radiation budget but could have substantial local radiative effects. © 2014 The Author(s) Published by the Royal Society. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26270671','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26270671"><span>Evidence of Coal-Fly-Ash Toxic Chemical <span class="hlt">Geoengineering</span> in the Troposphere: Consequences for Public Health.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Herndon, J Marvin</p> <p>2015-08-11</p> <p>The widespread, intentional and increasingly frequent chemical emplacement in the troposphere has gone unidentified and unremarked in the scientific literature for years. The author presents evidence that toxic coal combustion fly ash is the most likely <span class="hlt">aerosolized</span> particulate sprayed by tanker-jets for <span class="hlt">geoengineering</span>, weather-modification and climate-modification purposes and describes some of the multifold consequences on public health. Two methods are employed: (1) Comparison of 8 elements analyzed in rainwater, leached from <span class="hlt">aerosolized</span> particulates, with corresponding elements leached into water from coal fly ash in published laboratory experiments, and (2) Comparison of 14 elements analyzed in dust collected outdoors on a high-efficiency particulate air (HEPA) filter with corresponding elements analyzed in un-leached coal fly ash material. The results show: (1) the assemblage of elements in rainwater and in the corresponding experimental leachate are essentially identical. At a 99% confidence interval, they have identical means (T-test) and identical variances (F-test); and (2) the assemblage of elements in the HEPA dust and in the corresponding average un-leached coal fly ash are likewise essentially identical. The consequences on public health are profound, including exposure to a variety of toxic heavy metals, radioactive elements, and neurologically-implicated chemically mobile aluminum released by body moisture in situ after inhalation or through transdermal induction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1344653-dynamic-climate-emulators-solar-geoengineering','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1344653-dynamic-climate-emulators-solar-geoengineering"><span>Dynamic climate emulators for solar <span class="hlt">geoengineering</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>MacMartin, Douglas G.; Kravitz, Ben</p> <p>2016-12-22</p> <p>Climate emulators trained on existing simulations can be used to project project the climate effects that result from different possible future pathways of anthropogenic forcing, without further relying on general circulation model (GCM) simulations. We extend this idea to include different amounts of solar <span class="hlt">geoengineering</span> in addition to different pathways of greenhouse gas concentrations, by training emulators from a multi-model ensemble of simulations from the <span class="hlt">Geoengineering</span> Model Intercomparison Project (GeoMIP). The emulator is trained on the abrupt 4 × CO 2 and a compensating solar reduction simulation (G1), and evaluated by comparing predictions against a simulated 1 % per yearmore » CO 2 increase and a similarly smaller solar reduction (G2). We find reasonable agreement in most models for predicting changes in temperature and precipitation (including regional effects), and annual-mean Northern Hemisphere sea ice extent, with the difference between simulation and prediction typically being smaller than natural variability. This verifies that the linearity assumption used in constructing the emulator is sufficient for these variables over the range of forcing considered. Annual-minimum Northern Hemisphere sea ice extent is less well predicted, indicating a limit to the linearity assumption.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45.1030D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45.1030D"><span>Tailoring Meridional and Seasonal Radiative Forcing by Sulfate <span class="hlt">Aerosol</span> Solar <span class="hlt">Geoengineering</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dai, Z.; Weisenstein, D. K.; Keith, D. W.</p> <p>2018-01-01</p> <p>We study the possibility of designing solar radiation management schemes to achieve a desired meridional radiative forcing (RF) profile using a two-dimensional chemistry-transport-<span class="hlt">aerosol</span> model. Varying SO2 or H2SO4 injection latitude, altitude, and season, we compute RF response functions for a broad range of possible injection schemes, finding that linear combinations of these injection cases can roughly achieve RF profiles that have been proposed to accomplish various climate objectives. Globally averaged RF normalized by the sulfur injection rate (the radiative efficacy) is largest for injections at high altitudes, near the equator, and using emission of H2SO4 vapor into an aircraft wake to produce accumulation-mode particles. There is a trade-off between radiative efficacy and control as temporal and spatial control is best achieved with injections at lower altitudes and higher latitudes. These results may inform studies using more realistic models that couple <span class="hlt">aerosol</span> microphysics, chemistry, and stratospheric dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017isms.confEFA11K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017isms.confEFA11K"><span>Photochemical Formation of Sulfur-Containing <span class="hlt">Aerosols</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kroll, Jay A.; Vaida, Veronica</p> <p>2017-06-01</p> <p>In order to understand planetary climate systems, modeling the properties of atmospheric <span class="hlt">aerosols</span> is vital. <span class="hlt">Aerosol</span> formation plays an important role in planetary climates and is tied to feedback loops that can either warm or cool a planet. Sulfur compounds are known to play an important role in new particle <span class="hlt">aerosol</span> formation and have been observed in a number of planetary atmospheres throughout our solar system. Our current understanding of sulfur chemistry explains much of what we observe in Earth's atmosphere; however, several discrepancies arise when comparing observations of the Venusian atmosphere with model predictions. This suggests that there are still problems in our fundamental understanding of sulfur chemistry. This is concerning given recent renewed interest in sulfate injections in the stratosphere for solar radiation management <span class="hlt">geo-engineering</span> schemes. We investigate the role of sunlight as a potential driver of the formation of sulfur-containing <span class="hlt">aerosols</span>. I will present recent work investigating the generation of large quantities of <span class="hlt">aerosol</span> from the irradiation of mixtures of SO_2 with water and organic species, using a solar simulator that mimics the light that is available in the Earth's troposphere and the Venusian middle atmosphere. I will present on recent work done in our lab suggesting the formation of sulfurous acid, H_2SO_3, and describe experimental work that supports this proposed mechanism. Additionally I will present on new work showing the highly reactive nature of electronically excited SO_2 with saturated alkane species. The implications of this photochemically induced sulfur <span class="hlt">aerosol</span> formation in the atmosphere of Earth and other planetary atmospheres will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25224904','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25224904"><span>Deliberative Mapping of options for tackling climate change: Citizens and specialists 'open up' appraisal of <span class="hlt">geoengineering</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bellamy, Rob; Chilvers, Jason; Vaughan, Naomi E</p> <p>2016-04-01</p> <p>Appraisals of deliberate, large-scale interventions in the earth's climate system, known collectively as '<span class="hlt">geoengineering</span>', have largely taken the form of narrowly framed and exclusive expert analyses that prematurely 'close down' upon particular proposals. Here, we present the findings from the first 'upstream' appraisal of <span class="hlt">geoengineering</span> to deliberately 'open up' to a broader diversity of framings, knowledges and future pathways. We report on the citizen strand of an innovative analytic-deliberative participatory appraisal process called Deliberative Mapping. A select but diverse group of sociodemographically representative citizens from Norfolk (United Kingdom) were engaged in a deliberative multi-criteria appraisal of <span class="hlt">geoengineering</span> proposals relative to other options for tackling climate change, in parallel to symmetrical appraisals by diverse experts and stakeholders. Despite seeking to map divergent perspectives, a remarkably consistent view of option performance emerged across both the citizens' and the specialists' deliberations, where <span class="hlt">geoengineering</span> proposals were outperformed by mitigation alternatives. © The Author(s) 2014.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRD..11811036T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRD..11811036T"><span>The hydrological impact of <span class="hlt">geoengineering</span> in the <span class="hlt">Geoengineering</span> Model Intercomparison Project (GeoMIP)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tilmes, Simone; Fasullo, John; Lamarque, Jean-Francois; Marsh, Daniel R.; Mills, Michael; Alterskjær, Kari; Muri, Helene; Kristjánsson, Jón E.; Boucher, Olivier; Schulz, Michael; Cole, Jason N. S.; Curry, Charles L.; Jones, Andy; Haywood, Jim; Irvine, Peter J.; Ji, Duoying; Moore, John C.; Karam, Diana B.; Kravitz, Ben; Rasch, Philip J.; Singh, Balwinder; Yoon, Jin-Ho; Niemeier, Ulrike; Schmidt, Hauke; Robock, Alan; Yang, Shuting; Watanabe, Shingo</p> <p>2013-10-01</p> <p>The hydrological impact of enhancing Earth's albedo by solar radiation management is investigated using simulations from 12 Earth System models contributing to the <span class="hlt">Geoengineering</span> Model Intercomparison Project (GeoMIP). We contrast an idealized experiment, G1, where the global mean radiative forcing is kept at preindustrial conditions by reducing insolation while the CO2 concentration is quadrupled to a 4×CO2 experiment. The reduction of evapotranspiration over land with instantaneously increasing CO2 concentrations in both experiments largely contributes to an initial reduction in evaporation. A warming surface associated with the transient adjustment in 4×CO2 generates an increase of global precipitation by around 6.9% with large zonal and regional changes in both directions, including a precipitation increase of 10% over Asia and a reduction of 7% for the North American summer monsoon. Reduced global evaporation persists in G1 with temperatures close to preindustrial conditions. Global precipitation is reduced by around 4.5%, and significant reductions occur over monsoonal land regions: East Asia (6%), South Africa (5%), North America (7%), and South America (6%). The general precipitation performance in models is discussed in comparison to observations. In contrast to the 4×CO2 experiment, where the frequency of months with heavy precipitation intensity is increased by over 50% in comparison to the control, a reduction of up to 20% is simulated in G1. These changes in precipitation in both total amount and frequency of extremes point to a considerable weakening of the hydrological cycle in a <span class="hlt">geoengineered</span> world.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1439705-radiative-chemical-response-interactive-stratospheric-sulfate-aerosols-fully-coupled-cesm1-waccm-stratospheric-aerosols-cesm1-waccm','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1439705-radiative-chemical-response-interactive-stratospheric-sulfate-aerosols-fully-coupled-cesm1-waccm-stratospheric-aerosols-cesm1-waccm"><span>Radiative and Chemical Response to Interactive Stratospheric Sulfate <span class="hlt">Aerosols</span> in Fully Coupled CESM1(WACCM): Stratospheric <span class="hlt">Aerosols</span> in CESM1(WACCM)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Mills, Michael J.; Richter, Jadwiga H.; Tilmes, Simone</p> <p></p> <p>We present a new version of the Community Earth System Model, version 1 (CESM1) with the Whole Atmosphere Community Climate Model (WACCM) featuring numerous improvements that are unique among earth system models. Improved horizontal resolution, dynamics, and chemistry now provide the development of an internally generated quasi-biennial oscillation, and significant improvements to temperatures and ozone throughout the stratosphere. The prognostic treatment of stratospheric sulfate <span class="hlt">aerosols</span> is shown to represent well the evolution of stratospheric <span class="hlt">aerosol</span> optical depth and perturbations to solar and longwave radiation following volcanic eruptions. We identify the inclusion of interactive OH chemistry as crucial to the studymore » of <span class="hlt">aerosol</span> formation following large inputs of SO2 to the stratosphere. We show that depletion of OH levels within the dense SO2 cloud in the first weeks following the June 1991 eruption of Mt. Pinatubo significantly prolonged the e-folding decay time for SO2 oxidation to 47 days. Previous observational and model studies showing a 30-day decay time have not accounted for the large initial losses of SO2 on ash and ice in the first 7-9 days following the eruption, and have not correctly accounted for OH depletion. The completeness of the chemistry, dynamics, and <span class="hlt">aerosol</span> microphysics in WACCM uniquely qualify it for studies of stratospheric sulfate <span class="hlt">aerosol</span> <span class="hlt">geoengineering</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ACP....1711913X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ACP....1711913X"><span>Impacts of stratospheric sulfate <span class="hlt">geoengineering</span> on tropospheric ozone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xia, Lili; Nowack, Peer J.; Tilmes, Simone; Robock, Alan</p> <p>2017-10-01</p> <p>A range of solar radiation management (SRM) techniques has been proposed to counter anthropogenic climate change. Here, we examine the potential effects of stratospheric sulfate <span class="hlt">aerosols</span> and solar insolation reduction on tropospheric ozone and ozone at Earth's surface. Ozone is a key air pollutant, which can produce respiratory diseases and crop damage. Using a version of the Community Earth System Model from the National Center for Atmospheric Research that includes comprehensive tropospheric and stratospheric chemistry, we model both stratospheric sulfur injection and solar irradiance reduction schemes, with the aim of achieving equal levels of surface cooling relative to the Representative Concentration Pathway 6.0 scenario. This allows us to compare the impacts of sulfate <span class="hlt">aerosols</span> and solar dimming on atmospheric ozone concentrations. Despite nearly identical global mean surface temperatures for the two SRM approaches, solar insolation reduction increases global average surface ozone concentrations, while sulfate injection decreases it. A fundamental difference between the two <span class="hlt">geoengineering</span> schemes is the importance of heterogeneous reactions in the photochemical ozone balance with larger stratospheric sulfate abundance, resulting in increased ozone depletion in mid- and high latitudes. This reduces the net transport of stratospheric ozone into the troposphere and thus is a key driver of the overall decrease in surface ozone. At the same time, the change in stratospheric ozone alters the tropospheric photochemical environment due to enhanced ultraviolet radiation. A shared factor among both SRM scenarios is decreased chemical ozone loss due to reduced tropospheric humidity. Under insolation reduction, this is the dominant factor giving rise to the global surface ozone increase. Regionally, both surface ozone increases and decreases are found for both scenarios; that is, SRM would affect regions of the world differently in terms of air pollution. In conclusion</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGC41B0562H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGC41B0562H"><span>A Consideration of the Health and Environmental Risks/Effects of <span class="hlt">Geoengineering</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hemming, B. L.; Felgenhauer, T. N.; Miller, C. A.</p> <p>2014-12-01</p> <p>The views expressed in this abstract are those of the authors and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency. A number of <span class="hlt">geoengineering</span> strategies have been proposed and, to date, a few are being seriously investigated as possible approaches to reducing the degree of climate change. Whether under the broad rubrics of solar radiation management (SRM) or carbon dioxide removal (CDR), these projects would involve major, intentional intervention in the world's climate. Even if successful in off-setting the global radiative imbalance induced by human activities, it is not at all clear how well humans and the ecosystems upon which they depend will weather the climate system perturbations induced by the implementation of a large-scale <span class="hlt">geoengineering</span> program. It is reasonable to expect that such perturbations could exacerbate the existing health and environmental consequences of anthropogenic climate change at large and small scales, or create entirely new ones. An accounting of the derivative physical and biological effects of consequence to human health and ecosystems welfare that may result from the use of <span class="hlt">geoengineering</span> is a necessary part of any policy-relevant analysis. However, the scientific understanding required to quantitatively assess these potential impacts is absent in most cases, and still nascent in others. Furthermore, current discussions and existing literature lack the fully integrated "systems" approach required for adequately assessing the short- and long-term impacts of <span class="hlt">geoengineering</span> strategies on ecosystems and human populations. We present an overview of critical science questions, including broad questions concerning the potential response of the complex earth system to further human interference and those concerning potential impacts to local environmental metrics such as air and water quality and ecosystem viability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4555286','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4555286"><span>Evidence of Coal-Fly-Ash Toxic Chemical <span class="hlt">Geoengineering</span> in the Troposphere: Consequences for Public Health</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Herndon, J. Marvin</p> <p>2015-01-01</p> <p>The widespread, intentional and increasingly frequent chemical emplacement in the troposphere has gone unidentified and unremarked in the scientific literature for years. The author presents evidence that toxic coal combustion fly ash is the most likely <span class="hlt">aerosolized</span> particulate sprayed by tanker-jets for <span class="hlt">geoengineering</span>, weather-modification and climate-modification purposes and describes some of the multifold consequences on public health. Two methods are employed: (1) Comparison of 8 elements analyzed in rainwater, leached from <span class="hlt">aerosolized</span> particulates, with corresponding elements leached into water from coal fly ash in published laboratory experiments, and (2) Comparison of 14 elements analyzed in dust collected outdoors on a high-efficiency particulate air (HEPA) filter with corresponding elements analyzed in un-leached coal fly ash material. The results show: (1) the assemblage of elements in rainwater and in the corresponding experimental leachate are essentially identical. At a 99% confidence interval, they have identical means (T-test) and identical variances (F-test); and (2) the assemblage of elements in the HEPA dust and in the corresponding average un-leached coal fly ash are likewise essentially identical. The consequences on public health are profound, including exposure to a variety of toxic heavy metals, radioactive elements, and neurologically-implicated chemically mobile aluminum released by body moisture in situ after inhalation or through transdermal induction. PMID:26270671</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1910394W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1910394W"><span><span class="hlt">Geoengineering</span> Outlet Glaciers and Ice Streams</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wolovick, Michael</p> <p>2017-04-01</p> <p>Mass loss from Greenland and Antarctica is highly sensitive to the presence of warm ocean water that drives melting of ice shelves and marine terminated glaciers. This warm water resides offshore at depth and accesses the grounding line through deep but narrow troughs and fjords. Here, we investigate the possibility of blocking warm water transport through these choke points with an artificial sill. Using a simple width-averaged model of ice stream flow coupled to a buoyant-plume model of submarine melt, we find that grounding line retreat and sea level rise can be delayed or reversed for hundreds of years if warm water is prevented from accessing outlet glaciers and ice-shelf cavities. Glaciers with a floating shelf exhibit a strong response to the presence of the artificial sill regardless of our choice of calving law, while tidewater glaciers require a strong linkage between submarine melt and iceberg calving for the artificial sill to have an effect. As a result of this difference and as a result of differing degrees of overdeepening in the basal topography, Antarctica and Greenland present very different societal cost-benefit analyses. Intervention in Greenland would be low-cost and low-reward: the volume of the artificial sill is comparable to existing large public works projects such as the Dubai Islands or the Suez Canal, but the magnitude of averted sea-level rise is small, the success of the intervention depends on the choice of calving law, and the glaciers return to their non-<span class="hlt">geoengineered</span> trajectories within one to two centuries. Intervention in Antarctica, on the other hand, would be high-cost and high-reward: the volume of the artificial sill is one to two orders of magnitude greater, but the averted sea level rise is much larger, the intervention is successful regardless of the choice of calving law, and the ice streams remain far from their non-<span class="hlt">geoengineered</span> trajectories throughout the 1000 year duration of our model runs. In both cases, an</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NatCC...3..660H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NatCC...3..660H"><span>Asymmetric forcing from stratospheric <span class="hlt">aerosols</span> impacts Sahelian rainfall</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haywood, Jim M.; Jones, Andy; Bellouin, Nicolas; Stephenson, David</p> <p>2013-07-01</p> <p>The Sahelian drought of the 1970s-1990s was one of the largest humanitarian disasters of the past 50 years, causing up to 250,000 deaths and creating 10 million refugees. It has been attributed to natural variability, over-grazing and the impact of industrial emissions of sulphur dioxide. Each mechanism can influence the Atlantic sea surface temperature gradient, which is strongly coupled to Sahelian precipitation. We suggest that sporadic volcanic eruptions in the Northern Hemisphere also strongly influence this gradient and cause Sahelian drought. Using de-trended observations from 1900 to 2010, we show that three of the four driest Sahelian summers were preceded by substantial Northern Hemisphere volcanic eruptions. We use a state-of-the-art coupled global atmosphere-ocean model to simulate both episodic volcanic eruptions and <span class="hlt">geoengineering</span> by continuous deliberate injection into the stratosphere. In either case, large asymmetric stratospheric <span class="hlt">aerosol</span> loadings concentrated in the Northern Hemisphere are a harbinger of Sahelian drought whereas those concentrated in the Southern Hemisphere induce a greening of the Sahel. Further studies of the detailed regional impacts on the Sahel and other vulnerable areas are required to inform policymakers in developing careful consensual global governance before any practical solar radiation management <span class="hlt">geoengineering</span> scheme is implemented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/987121','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/987121"><span><span class="hlt">Geoengineering</span> the Earth's Climate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Google Tech Talks</p> <p>2008-01-08</p> <p>Emergency preparedness is generally considered to be a good thing, yet there is no plan regarding what we might do should we be faced with a climate emergency. Such an emergency could take the form of a rapid shift in precipitation patterns, a collapse of the great ice sheets, the imminent triggering of strong climate system feedbacks, or perhaps the loss of valuable ecosystems. Over the past decade, we have used climate models to investigate the potential to reverse some of the effects of greenhouse gases in the atmosphere by deflecting some incoming sunlight back to space. This would probablymore » be most cost-effectively achieved with the placement of small particles in or above the stratosphere. Our model simulations indicate that such <span class="hlt">geoengineering</span> approaches could potentially bring our climate closer to the state is was in prior to the introduction of greenhouse gases. This talk will present much of what is known about such <span class="hlt">geoengineering</span> approaches, and raise a range of issues likely to stimulate lively discussion. Speaker: Ken Caldeira Ken Caldeira is a scientist at the Carnegie Institution Department of Global Ecology and a Professor (by courtesy) at the Stanford University Department of Environmental and Earth System Sciences. Previously, he worked for 12 years in the Energy and Environment Directorate at the Lawrence Livermore National Laboratory (Department of Energy). His research interests include the numerical simulation of Earth's climate, carbon, and biogeochemistry; ocean acidification; climate emergency response systems; evaluating approaches to supplying environmentally-friendly energy services; ocean carbon sequestration; long-term evolution of climate and geochemical cycles; and marine biogeochemical cycles. Caldeira has a B.A. in Philosophy from Rutgers College and an M.S. and Ph.D. in Atmospheric Sciences from New York University.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/sciencecinema/biblio/987121','SCIGOVIMAGE-SCICINEMA'); return false;" href="http://www.osti.gov/sciencecinema/biblio/987121"><span><span class="hlt">Geoengineering</span> the Earth's Climate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/sciencecinema/">ScienceCinema</a></p> <p>Google Tech Talks</p> <p>2017-12-09</p> <p>Emergency preparedness is generally considered to be a good thing, yet there is no plan regarding what we might do should we be faced with a climate emergency. Such an emergency could take the form of a rapid shift in precipitation patterns, a collapse of the great ice sheets, the imminent triggering of strong climate system feedbacks, or perhaps the loss of valuable ecosystems. Over the past decade, we have used climate models to investigate the potential to reverse some of the effects of greenhouse gases in the atmosphere by deflecting some incoming sunlight back to space. This would probably be most cost-effectively achieved with the placement of small particles in or above the stratosphere. Our model simulations indicate that such <span class="hlt">geoengineering</span> approaches could potentially bring our climate closer to the state is was in prior to the introduction of greenhouse gases. This talk will present much of what is known about such <span class="hlt">geoengineering</span> approaches, and raise a range of issues likely to stimulate lively discussion. Speaker: Ken Caldeira Ken Caldeira is a scientist at the Carnegie Institution Department of Global Ecology and a Professor (by courtesy) at the Stanford University Department of Environmental and Earth System Sciences. Previously, he worked for 12 years in the Energy and Environment Directorate at the Lawrence Livermore National Laboratory (Department of Energy). His research interests include the numerical simulation of Earth's climate, carbon, and biogeochemistry; ocean acidification; climate emergency response systems; evaluating approaches to supplying environmentally-friendly energy services; ocean carbon sequestration; long-term evolution of climate and geochemical cycles; and marine biogeochemical cycles. Caldeira has a B.A. in Philosophy from Rutgers College and an M.S. and Ph.D. in Atmospheric Sciences from New York University.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.A33L..04J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.A33L..04J"><span>Simulation of how a <span class="hlt">geo-engineering</span> intervention to restore arctic sea ice might work in practice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jackson, L. S.; Crook, J. A.; Forster, P.; Jarvis, A.; Leedal, D.; Ridgwell, A. J.; Vaughan, N.</p> <p>2013-12-01</p> <p>The declining trend in annual minimum Arctic sea ice coverage and years of more pronounced drops like 2007 and 2012 raise the prospect of an Arctic Ocean largely free of sea ice in late summer and the potential for a climate crisis or emergency. In a novel computer simulation, we treated one realisation of a climate model (HadGEM2) as the real world and tried to restore its Arctic sea ice by the rapid deployment of <span class="hlt">geo-engineering</span> with emission of SO2 into the Arctic stratosphere. The objective was to restore the annual minimum Arctic sea ice coverage to levels seen in the late twentieth century using as little <span class="hlt">geo-engineering</span> as possible. We took intervention decisions as one might do in the real world: by committee, using a limited set of uncertain 'observations' from our simulated world and using models and control theory to plan the best intervention strategy for the coming year - so learning as we went and being thrown off course by future volcanoes and technological breakdowns. Uncertainties in real world observations were simulated by applying noise to emerging results from the climate model. Volcanic forcing of twenty-first century climate was included with the timing and magnitude of the simulated eruptions unknown by the '<span class="hlt">geo-engineers</span>' until after the year of the eruption. Monitoring of Arctic sea ice with the option to intervene with SO2 emissions started from 2018 and continued to 2075. Simulated SO2 emissions were made in January-May each year at a latitude of 79o N and an altitude within the range of contemporary tanker aircraft. The magnitude of emissions was chosen annually using a model predictive control process calibrated using results from CMIP5 models (excluding HadGEM2), using the simplified climate model MAGICC and assimilation of emerging annual results from the HadGEM2 'real world'. We found that doubts in the minds of the '<span class="hlt">geo-engineers</span>' of the effectiveness and the side effects of their past intervention, and the veracity of the models</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28418005','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28418005"><span>Simulated climate effects of desert irrigation <span class="hlt">geoengineering</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheng, Wei; Moore, John C; Cao, Long; Ji, Duoying; Zhao, Liyun</p> <p>2017-04-18</p> <p><span class="hlt">Geoengineering</span>, the deliberate large-scale manipulation of earth's energy balance to counteract global warming, is an attractive proposition for sparsely populated deserts. We use the BNU and UVic Earth system models to simulate the effects of irrigating deserts under the RCP8.5 scenario. Previous studies focused on increasing desert albedo to reduce global warming; in contrast we examine how extending afforestation and ecological projects, that successfully improve regional environments, fair for <span class="hlt">geoengineering</span> purposes. As expected desert irrigation allows vegetation to grow, with bare soil or grass gradually becoming shrub or tree covered, with increases in terrestrial carbon storage of 90.3 Pg C (UVic-ESCM) - 143.9 Pg C (BNU-ESM). Irrigating global deserts makes the land surface temperature decrease by 0.48 °C and land precipitation increase by 100 mm yr -1 . In the irrigated areas, BNU-ESM simulates significant cooling of up to 4.2 °C owing to the increases in low cloud and latent heat which counteract the warming effect due to decreased surface albedo. Large volumes of water would be required to maintain global desert irrigation, equivalent 10 mm/year of global sea level (BNU-ESM) compensate for evapotranspiration losses. Differences in climate responses between the deserts prompt research into tailored albedo-irrigation schemes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGC33B1226R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGC33B1226R"><span>Effects of Solar <span class="hlt">Geoengineering</span> on Meridional Energy Transport and the ITCZ</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Russotto, R. D.; Ackerman, T. P.; Frierson, D. M.</p> <p>2016-12-01</p> <p>The polar amplification of warming and the ability of the intertropical convergence zone (ITCZ) to shift to the north or south are two very important problems in climate science. Examining these behaviors in global climate models (GCMs) running solar <span class="hlt">geoengineering</span> experiments is helpful not only for predicting the effects of solar <span class="hlt">geoengineering</span>, but also for understanding how these processes work under increased CO2. Both polar amplification and ITCZ shifts are closely related to the meridional transport of moist static energy (MSE) by the atmosphere. In this study we examine changes in MSE transport in 10 fully coupled GCMs in Experiment G1 of the <span class="hlt">Geoengineering</span> Model Intercomparison Project, in which the solar constant is reduced to compensate for abruptly quadrupled CO2 concentrations. In this experiment, poleward MSE transport decreases relative to preindustrial conditions in all models, in contrast to the CMIP5 abrupt4xCO2 experiment, in which poleward MSE transport increases. The increase in poleward MSE transport under increased CO2 is due to latent heat transport, as specific humidity increases faster in the tropics than at the poles; this mechanism is not present under G1 conditions, so the reduction in dry static energy transport due to a weakened equator-to-pole temperature gradient leads to weaker energy transport overall. Changes in cross-equatorial MSE transport in G1, meanwhile, are anticorrelated with shifts in the ITCZ. The northward ITCZ shift in G1 is 0.14 degrees in the multi-model mean and ranges from -0.33 to 0.89 degrees between the models. We examine the specific forcing and feedback terms responsible for changes in MSE transport in G1 by running experiments with a moist energy balance model. This work will help identify the largest sources of uncertainty regarding ITCZ shifts under solar <span class="hlt">geoengineering</span>, and will help improve our understanding of the reasons for the residual polar amplification that occurs in the G1 experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMGC43H1160I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMGC43H1160I"><span>Moderate solar <span class="hlt">geoengineering</span> greatly reduces the largest changes in climate whilst modestly increasing the changes in climate over a small fraction of the Earth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Irvine, P. J.; Keith, D.; He, J.; Vecchi, G.; Horowitz, L. W.</p> <p>2017-12-01</p> <p>Whilst solar <span class="hlt">geoengineering</span> reduces global temperature it cannot perfectly offset the climate effects of elevated CO2 concentrations. Solar <span class="hlt">geoengineering</span> has been shown to have a greater effect on the global hydrological cycle than CO2 and substantial differences in regional precipitation relative to a scenario without elevated CO2­ concentrations have been noted. In this study we evaluate a moderate scenario of solar <span class="hlt">geoengineering</span>, one which offsets 50% of the forcing from elevated CO2 concentrations, using a 25 Km resolution global climate model and verify these results using the <span class="hlt">Geoengineering</span> model Intercomparison project ensemble. We calculate the fraction of regions that would be better or worse off after solar <span class="hlt">geoengineering</span> deployment, defining those which see greater absolute change as worse off and vice versa. We find that 51% of the land area would be statistically significantly better off for precipitation, 33% for Precipitation minus evaporation (P-E), and that less than 3% would be worse off for precipitation, and 1% for P-E. We find that the fraction of the land area experiencing the largest changes in climate, defined as the upper quartile of the CO2 minus control anomaly, is greatly reduced for precipitation, P-E and 5-day maximum precipitation, and eliminated for mean and max annual temperature. The regions which are made worse off in precipitation or P-E by solar <span class="hlt">geoengineering</span> typically saw relatively little to no CO2 induced climate change and see relatively little to moderate change in the solar <span class="hlt">geoengineering</span> scenario. There is little overlap between the regions made worse off in terms of precipitation and P-E. In fact, whilst precipitation is reduced in almost all regions made worse off by solar <span class="hlt">geoengineering</span>, P-E is increased in the majority of regions made worse off. Overall, we find that for each variable considered solar <span class="hlt">geoengineering</span> greatly reduces the fraction of the world experiencing relatively large change and that those</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.3014G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.3014G"><span>A simple, physically-based method for evaluating the economic costs of <span class="hlt">geo-engineering</span> schemes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garrett, T. J.</p> <p>2009-04-01</p> <p>The consumption of primary energy (e.g coal, oil, uranium) by the global economy is done in expectation of a return on investment. For <span class="hlt">geo-engineering</span> schemes, however, the relationship between the primary energy consumption required and the economic return is, at first glance, quite different. The energy costs of a given scheme represent a removal of economically productive available energy to do work in the normal global economy. What are the economic implications of the energy consumption associated with <span class="hlt">geo-engineering</span> techniques? I will present a simple thermodynamic argument that, in general, real (inflation-adjusted) economic value has a fixed relationship to the rate of global primary energy consumption. This hypothesis will be shown to be supported by 36 years of available energy statistics and a two millennia period of statistics for global economic production. What is found from this analysis is that the value in any given inflation-adjusted 1990 dollar is sustained by a constant 9.7 +/- 0.3 milliwatts of global primary energy consumption. Thus, insofar as <span class="hlt">geo-engineering</span> is concerned, any scheme that requires some nominal fraction of continuous global primary energy output necessitates a corresponding inflationary loss of real global economic value. For example, if 1% of global energy output is required, at today's consumption rates of 15 TW this corresponds to an inflationary loss of 15 trillion 1990 dollars of real value. The loss will be less, however, if the <span class="hlt">geo-engineering</span> scheme also enables a demonstrable enhancement to global economic production capacity through climate modification.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1092643-climate-model-response-from-geoengineering-model-intercomparison-project-geomip','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1092643-climate-model-response-from-geoengineering-model-intercomparison-project-geomip"><span>Climate Model Response from the <span class="hlt">Geoengineering</span> Model Intercomparison Project (GeoMIP)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kravitz, Benjamin S.; Caldeira, Ken; Boucher, Olivier</p> <p>2013-08-09</p> <p>Solar geoengineering—deliberate reduction in the amount of solar radiation retained by the Earth—has been proposed as a means of counteracting some of the climatic effects of anthropogenic greenhouse gas emissions. We present results from Experiment G1 of the <span class="hlt">Geoengineering</span> Model Intercomparison Project, in which 12 climate models have simulated the climate response to an abrupt quadrupling of CO2 from preindustrial concentrations brought into radiative balance via a globally uniform reduction in insolation. Models show this reduction largely offsets global mean surface temperature increases due to quadrupled CO2 concentrations and prevents 97% of the Arctic sea ice loss that would otherwisemore » occur under high CO2 levels but, compared to the preindustrial climate, leaves the tropics cooler (-0.3 K) and the poles warmer (+0.8 K). Annual mean precipitation minus evaporation anomalies for G1 are less than 0.2mmday-1 in magnitude over 92% of the globe, but some tropical regions receive less precipitation, in part due to increased moist static stability and suppression of convection. Global average net primary productivity increases by 120% in G1 over simulated preindustrial levels, primarily from CO2 fertilization, but also in part due to reduced plant heat stress compared to a high CO2 world with no <span class="hlt">geoengineering</span>. All models show that uniform solar <span class="hlt">geoengineering</span> in G1 cannot simultaneously return regional and global temperature and hydrologic cycle intensity to preindustrial levels.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRD..118.8320K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRD..118.8320K"><span>Climate model response from the <span class="hlt">Geoengineering</span> Model Intercomparison Project (GeoMIP)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kravitz, Ben; Caldeira, Ken; Boucher, Olivier; Robock, Alan; Rasch, Philip J.; Alterskjær, Kari; Karam, Diana Bou; Cole, Jason N. S.; Curry, Charles L.; Haywood, James M.; Irvine, Peter J.; Ji, Duoying; Jones, Andy; Kristjánsson, Jón Egill; Lunt, Daniel J.; Moore, John C.; Niemeier, Ulrike; Schmidt, Hauke; Schulz, Michael; Singh, Balwinder; Tilmes, Simone; Watanabe, Shingo; Yang, Shuting; Yoon, Jin-Ho</p> <p>2013-08-01</p> <p>geoengineering—deliberate reduction in the amount of solar radiation retained by the Earth—has been proposed as a means of counteracting some of the climatic effects of anthropogenic greenhouse gas emissions. We present results from Experiment G1 of the <span class="hlt">Geoengineering</span> Model Intercomparison Project, in which 12 climate models have simulated the climate response to an abrupt quadrupling of CO2 from preindustrial concentrations brought into radiative balance via a globally uniform reduction in insolation. Models show this reduction largely offsets global mean surface temperature increases due to quadrupled CO2 concentrations and prevents 97% of the Arctic sea ice loss that would otherwise occur under high CO2 levels but, compared to the preindustrial climate, leaves the tropics cooler (-0.3 K) and the poles warmer (+0.8 K). Annual mean precipitation minus evaporation anomalies for G1 are less than 0.2 mm day-1 in magnitude over 92% of the globe, but some tropical regions receive less precipitation, in part due to increased moist static stability and suppression of convection. Global average net primary productivity increases by 120% in G1 over simulated preindustrial levels, primarily from CO2 fertilization, but also in part due to reduced plant heat stress compared to a high CO2 world with no <span class="hlt">geoengineering</span>. All models show that uniform solar <span class="hlt">geoengineering</span> in G1 cannot simultaneously return regional and global temperature and hydrologic cycle intensity to preindustrial levels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5394461','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5394461"><span>Simulated climate effects of desert irrigation <span class="hlt">geoengineering</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cheng, Wei; Moore, John C.; Cao, Long; Ji, Duoying; Zhao, Liyun</p> <p>2017-01-01</p> <p><span class="hlt">Geoengineering</span>, the deliberate large-scale manipulation of earth’s energy balance to counteract global warming, is an attractive proposition for sparsely populated deserts. We use the BNU and UVic Earth system models to simulate the effects of irrigating deserts under the RCP8.5 scenario. Previous studies focused on increasing desert albedo to reduce global warming; in contrast we examine how extending afforestation and ecological projects, that successfully improve regional environments, fair for <span class="hlt">geoengineering</span> purposes. As expected desert irrigation allows vegetation to grow, with bare soil or grass gradually becoming shrub or tree covered, with increases in terrestrial carbon storage of 90.3 Pg C (UVic-ESCM) – 143.9 Pg C (BNU-ESM). Irrigating global deserts makes the land surface temperature decrease by 0.48 °C and land precipitation increase by 100 mm yr−1. In the irrigated areas, BNU-ESM simulates significant cooling of up to 4.2 °C owing to the increases in low cloud and latent heat which counteract the warming effect due to decreased surface albedo. Large volumes of water would be required to maintain global desert irrigation, equivalent 10 mm/year of global sea level (BNU-ESM) compensate for evapotranspiration losses. Differences in climate responses between the deserts prompt research into tailored albedo-irrigation schemes. PMID:28418005</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGC41B0563J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGC41B0563J"><span><span class="hlt">Geoengineering</span>, Climate Harm, and Business as Usual</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jankunis, F. J.; Peacock, K.</p> <p>2014-12-01</p> <p>We define <span class="hlt">geoengineering</span> (GE) as the intentional use of technology to change the planet's climate. Many people believe GE is different in kind rather than degree from any other organized activity in human history. In fact, humans caused changes in the planet's climate long before the industrial age, and all organisms engineer their environments directly or indirectly. The relevant difference between this cumulative and generally inadvertent activity and GE is the presence of intention. Now that science has revealed the extent to which humans can change the climate, however, even the continuance of Business as Usual (BAU) is, in effect, a form of intentional GE, albeit one that will cause significant climate harm, defined as effects such as sea level rise that will impact human well-being. But as with all forms of engineering, the devil is in the details: what forms of GE should be tried first? Some methods, such as large-scale afforestation, are low risk but have long-term payoffs; others, such as <span class="hlt">aerosol</span> injection into the stratosphere, could help buy time in a warming crisis but have unknown side-effects and little long-term future. Climate change is a world-wide, inter-generational tragedy of the commons. Rational choice theory, the spatial and temporal extension of the problem, poorly fitted moral frameworks, and political maneuvering are all factors that inhibit solutions to the climate tragedy of the commons. The longer that such factors are allowed to dominate decision-making (or the lack thereof) the more likely it is that humanity will be forced to resort to riskier and more drastic forms of GE. We argue that this fact brings an additional measure of urgency to the search for ways to engineer the climate differently so as to avoid climate harm in the most lasting and least risky way.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ERL....12c4009H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ERL....12c4009H"><span>Impact of the GeoMIP G1 sunshade <span class="hlt">geoengineering</span> experiment on the Atlantic meridional overturning circulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hong, Yu; Moore, John C.; Jevrejeva, Svetlana; Ji, Duoying; Phipps, Steven J.; Lenton, Andrew; Tilmes, Simone; Watanabe, Shingo; Zhao, Liyun</p> <p>2017-03-01</p> <p>We analyze the multi-earth system model responses of ocean temperatures and the Atlantic Meridional Overturning Circulation (AMOC) under an idealized solar radiation management scenario (G1) from the <span class="hlt">Geoengineering</span> Model Intercomparison Project. All models simulate warming of the northern North Atlantic relative to no <span class="hlt">geoengineering</span>, despite <span class="hlt">geoengineering</span> substantially offsetting the increases in mean global ocean temperatures. Increases in the temperature of the North Atlantic Ocean at the surface (˜0.25 K) and at a depth of 500 m (˜0.10 K) are mainly due to a 10 Wm-2 reduction of total heat flux from ocean to atmosphere. Although the AMOC is slightly reduced under the solar dimming scenario, G1, relative to piControl, it is about 37% stronger than under abrupt4 × CO2 . The reduction of the AMOC under G1 is mainly a response to the heat flux change at the northern North Atlantic rather than to changes in the water flux and the wind stress. The AMOC transfers heat from tropics to high latitudes, helping to warm the high latitudes, and its strength is maintained under solar dimming rather than weakened by greenhouse gas forcing acting alone. Hence the relative reduction in high latitude ocean temperatures provided by solar radiation <span class="hlt">geoengineering</span>, would tend to be counteracted by the correspondingly active AMOC circulation which furthermore transports warm surface waters towards the Greenland ice sheet, warming Arctic sea ice and permafrost.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1042535-ecosystem-impacts-geoengineering-review-developing-science-plan','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1042535-ecosystem-impacts-geoengineering-review-developing-science-plan"><span>ECOSYSTEM IMPACTS OF <span class="hlt">GEOENGINEERING</span>: A Review for Developing a Science Plan</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Russell, Lynn M.; Rasch, Philip J.; Mace, Georgina</p> <p>2012-06-01</p> <p><span class="hlt">Geoengineering</span> methods are intended to reduce the magnitude of climate change. Climate change in some regions is already having demonstrable effects on ecosystem structure and functioning. Two different types of <span class="hlt">geoengineering</span> activities have been proposed: carbon dioxide removal (CDR), which includes a range of engineered and biological processes to remove carbon dioxide (CO2) from the atmosphere, and solar radiation management (SRM, or sunlight reflection methods), whereby a small percentage of sunlight is reflected back into space to offset warming from greenhouse gases. In this review, we evaluate some of the possible impacts of CDR and SRM on the physical climatemore » and their subsequent influence on ecosystems, including the risks and uncertainties associated with new kinds of purposeful perturbations to Earth. Specifically, we find evidence that, if implemented successfully, some CDR methods and continue use of some SRM methods) could alleviate some of the deleterious ecosystem impacts associated with climate changes that might occur in the foreseeable future.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeoRL..40.1799C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeoRL..40.1799C"><span>Tropical coral reef habitat in a <span class="hlt">geoengineered</span>, high-CO2 world</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Couce, E.; Irvine, P. J.; Gregorie, L. J.; Ridgwell, A.; Hendy, E. J.</p> <p>2013-05-01</p> <p>Continued anthropogenic CO2 emissions are expected to impact tropical coral reefs by further raising sea surface temperatures (SST) and intensifying ocean acidification (OA). Although <span class="hlt">geoengineering</span> by means of solar radiation management (SRM) may mitigate temperature increases, OA will persist, raising important questions regarding the impact of different stressor combinations. We apply statistical Bioclimatic Envelope Models to project changes in shallow water tropical coral reef habitat as a single niche (without resolving biodiversity or community composition) under various representative concentration pathway and SRM scenarios, until 2070. We predict substantial reductions in habitat suitability centered on the Indo-Pacific Warm Pool under net anthropogenic radiative forcing of ≥3.0 W/m2. The near-term dominant risk to coral reefs is increasing SSTs; below 3 W/m2 reasonably favorable conditions are maintained, even when achieved by SRM with persisting OA. "Optimal" mitigation occurs at 1.5 W/m2 because tropical SSTs overcool in a fully <span class="hlt">geoengineered</span> (i.e., preindustrial global mean temperature) world.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4819797','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4819797"><span>Deliberative Mapping of options for tackling climate change: Citizens and specialists ‘open up’ appraisal of <span class="hlt">geoengineering</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bellamy, Rob; Chilvers, Jason; Vaughan, Naomi E.</p> <p>2014-01-01</p> <p>Appraisals of deliberate, large-scale interventions in the earth’s climate system, known collectively as ‘geoengineering’, have largely taken the form of narrowly framed and exclusive expert analyses that prematurely ‘close down’ upon particular proposals. Here, we present the findings from the first ‘upstream’ appraisal of <span class="hlt">geoengineering</span> to deliberately ‘open up’ to a broader diversity of framings, knowledges and future pathways. We report on the citizen strand of an innovative analytic–deliberative participatory appraisal process called Deliberative Mapping. A select but diverse group of sociodemographically representative citizens from Norfolk (United Kingdom) were engaged in a deliberative multi-criteria appraisal of <span class="hlt">geoengineering</span> proposals relative to other options for tackling climate change, in parallel to symmetrical appraisals by diverse experts and stakeholders. Despite seeking to map divergent perspectives, a remarkably consistent view of option performance emerged across both the citizens’ and the specialists’ deliberations, where <span class="hlt">geoengineering</span> proposals were outperformed by mitigation alternatives. PMID:25224904</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4240951','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4240951"><span>Process-model simulations of cloud albedo enhancement by <span class="hlt">aerosols</span> in the Arctic</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kravitz, Ben; Wang, Hailong; Rasch, Philip J.; Morrison, Hugh; Solomon, Amy B.</p> <p>2014-01-01</p> <p>A cloud-resolving model is used to simulate the effectiveness of Arctic marine cloud brightening via injection of cloud condensation nuclei (CCN), either through <span class="hlt">geoengineering</span> or other increased sources of Arctic <span class="hlt">aerosols</span>. An updated cloud microphysical scheme is employed, with prognostic CCN and cloud particle numbers in both liquid and mixed-phase marine low clouds. Injection of CCN into the marine boundary layer can delay the collapse of the boundary layer and increase low-cloud albedo. Albedo increases are stronger for pure liquid clouds than mixed-phase clouds. Liquid precipitation can be suppressed by CCN injection, whereas ice precipitation (snow) is affected less; thus, the effectiveness of brightening mixed-phase clouds is lower than for liquid-only clouds. CCN injection into a clean regime results in a greater albedo increase than injection into a polluted regime, consistent with current knowledge about aerosol–cloud interactions. Unlike previous studies investigating warm clouds, dynamical changes in circulation owing to precipitation changes are small. According to these results, which are dependent upon the representation of ice nucleation processes in the employed microphysical scheme, Arctic <span class="hlt">geoengineering</span> is unlikely to be effective as the sole means of altering the global radiation budget but could have substantial local radiative effects. PMID:25404677</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27593289','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27593289"><span>Characterization of particulate products for aging of ethylbenzene secondary organic <span class="hlt">aerosol</span> in the presence of ammonium sulfate seed <span class="hlt">aerosol</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Mingqiang; Zhang, Jiahui; Cai, Shunyou; Liao, Yingmin; Zhao, Weixiong; Hu, Changjin; Gu, Xuejun; Fang, Li; Zhang, Weijun</p> <p>2016-09-01</p> <p>Aging of secondary organic <span class="hlt">aerosol</span> (SOA) particles formed from OH- initiated oxidation of ethylbenzene in the presence of high mass (100-300μg/m(3)) concentrations of (NH4)2SO4 seed <span class="hlt">aerosol</span> was investigated in a home-made smog chamber in this study. The chemical composition of aged ethylbenzene SOA particles was measured using an <span class="hlt">aerosol</span> laser time-of-flight mass spectrometer (ALTOFMS) coupled with a Fuzzy C-Means (FCM) clustering algorithm. Experimental results showed that nitrophenol, ethyl-nitrophenol, 2,4-dinitrophenol, methyl glyoxylic acid, 5-ethyl-6-oxo-2,4-hexadienoic acid, 2-ethyl-2,4-hexadiendioic acid, 2,3-dihydroxy-5-ethyl-6-oxo-4-hexenoic acid, 1H-imidazole, hydrated N-glyoxal <span class="hlt">substituted</span> 1H-imidazole, hydrated glyoxal dimer <span class="hlt">substituted</span> imidazole, 1H-imidazole-2-carbaldehyde, N-glyoxal <span class="hlt">substituted</span> hydrated 1H-imidazole-2-carbaldehyde and high-molecular-weight (HMW) components were the predominant products in the aged particles. Compared to the previous aromatic SOA aging studies, imidazole compounds, which can absorb solar radiation effectively, were newly detected in aged ethylbenzene SOA in the presence of high concentrations of (NH4)2SO4 seed <span class="hlt">aerosol</span>. These findings provide new information for discussing aromatic SOA aging mechanisms. Copyright © 2016. Published by Elsevier B.V.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRD..12213061M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRD..12213061M"><span>Radiative and Chemical Response to Interactive Stratospheric Sulfate <span class="hlt">Aerosols</span> in Fully Coupled CESM1(WACCM)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mills, Michael J.; Richter, Jadwiga H.; Tilmes, Simone; Kravitz, Ben; MacMartin, Douglas G.; Glanville, Anne A.; Tribbia, Joseph J.; Lamarque, Jean-François; Vitt, Francis; Schmidt, Anja; Gettelman, Andrew; Hannay, Cecile; Bacmeister, Julio T.; Kinnison, Douglas E.</p> <p>2017-12-01</p> <p>We present new insights into the evolution and interactions of stratospheric <span class="hlt">aerosol</span> using an updated version of the Whole Atmosphere Community Climate Model (WACCM). Improved horizontal resolution, dynamics, and chemistry now produce an internally generated quasi-biennial oscillation and significant improvements to stratospheric temperatures and ozone compared to observations. We present a validation of WACCM column ozone and climate calculations against observations. The prognostic treatment of stratospheric sulfate <span class="hlt">aerosols</span> accurately represents the evolution of stratospheric <span class="hlt">aerosol</span> optical depth and perturbations to solar and longwave radiation following the June 1991 eruption of Mount Pinatubo. We confirm the inclusion of interactive OH chemistry as an important factor in the formation and initial distribution of <span class="hlt">aerosol</span> following large inputs of sulfur dioxide (SO2) to the stratosphere. We calculate that depletion of OH levels within the dense SO2 cloud in the first weeks following the Pinatubo eruption significantly prolonged the average initial e-folding decay time for SO2 oxidation to 47 days. Previous observational and model studies showing a 30 day decay time have not accounted for the large (30-55%) losses of SO2 on ash and ice within 7-9 days posteruption and have not correctly accounted for OH depletion. We examine the variability of <span class="hlt">aerosol</span> evolution in free-running climate simulations due to meteorology, with comparison to simulations nudged with specified dynamics. We assess calculated impacts of volcanic <span class="hlt">aerosols</span> on ozone loss with comparisons to observations. The completeness of the chemistry, dynamics, and <span class="hlt">aerosol</span> microphysics in WACCM qualify it for studies of stratospheric sulfate <span class="hlt">aerosol</span> <span class="hlt">geoengineering</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1038638-evaluating-wrf-chem-aerosol-indirect-effects-southeast-pacific-marine-stratocumulus-during-vocals-rex','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1038638-evaluating-wrf-chem-aerosol-indirect-effects-southeast-pacific-marine-stratocumulus-during-vocals-rex"><span>Evaluating WRF-Chem <span class="hlt">aerosol</span> indirect effects in Southeast Pacific marine stratocumulus during VOCALS-REx</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Saide, Pablo; Spak, S. N.; Carmichael, Gregory</p> <p>2012-03-30</p> <p>We evaluate a regional-scale simulation with the WRF-Chem model for the VAMOS (Variability of the American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx), which sampled the Southeast Pacific's persistent stratocumulus deck. Evaluation of VOCALS-REx ship-based and aircraft observations focuses on analyzing how <span class="hlt">aerosol</span> loading affects marine boundary layer (MBL) dynamics and cloud microphysics. We compare local time series and campaign averaged longitudinal gradients, and highlight differences in model simulations with (W) and without wet (NW) deposition processes. The higher <span class="hlt">aerosol</span> loadings in the NW case produce considerable changes in MBL dynamics and cloud microphysics, in accordance with the established conceptualmore » model of <span class="hlt">aerosol</span> indirect effects. These include increase in cloud albedo, increase in MBL and cloud heights, drizzle suppression, increase in liquid water content, and increase in cloud lifetime. Moreover, better statistical representation of <span class="hlt">aerosol</span> mass and number concentration improves model fidelity in reproducing observed spatial and temporal variability in cloud properties, including top and base height, droplet concentration, water content, rain rate, optical depth (COD) and liquid water path (LWP). Together, these help to quantify confidence in WRF-Chem's modeled <span class="hlt">aerosol</span>-cloud interactions, while identifying structural and parametric uncertainties including: irreversibility in rain wet removal; overestimation of marine DMS and sea salt emissions and accelerated aqueous sulfate conversion. Our findings suggest that WRF-Chem simulates marine cloud-<span class="hlt">aerosol</span> interactions at a level sufficient for applications in forecasting weather and air quality and studying <span class="hlt">aerosol</span> climate forcing, including the reliability required for policy analysis and <span class="hlt">geo-engineering</span> applications.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1439705-radiative-chemical-response-interactive-stratospheric-sulfate-aerosols-fully-coupled-cesm1-waccm','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1439705-radiative-chemical-response-interactive-stratospheric-sulfate-aerosols-fully-coupled-cesm1-waccm"><span>Radiative and Chemical Response to Interactive Stratospheric Sulfate <span class="hlt">Aerosols</span> in Fully Coupled CESM1(WACCM)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Mills, Mike; Richter, Jadwiga; Tilmes, S.</p> <p>2017-11-06</p> <p>We present a new version of the Community Earth System Model, version 1 (CESM1) with the Whole Atmosphere Community Climate Model (WACCM) featuring numerous improvements that are unique among earth system models. Improved horizontal resolution, dynamics, and chemistry now provide the development of an internally generated quasi-biennial oscillation, and significant improvements to temperatures and ozone throughout the stratosphere. The prognostic treatment of stratospheric sulfate <span class="hlt">aerosols</span> is shown to represent well the evolution of stratospheric <span class="hlt">aerosol</span> optical depth and perturbations to solar and longwave radiation following volcanic eruptions. We identify the inclusion of interactive OH chemistry as crucial to the studymore » of <span class="hlt">aerosol</span> formation following large inputs of SO2 to the stratosphere. We show that depletion of OH levels within the dense SO2 cloud in the first weeks following the June 1991 eruption of Mt. Pinatubo significantly prolonged the e-folding decay time for SO2 oxidation to 47 days. Previous observational and model studies showing a 30-day decay time have not accounted for the large initial losses of SO2 on ash and ice in the first 7-9 days following the eruption, and have not correctly accounted for OH depletion. The completeness of the chemistry, dynamics, and <span class="hlt">aerosol</span> microphysics in WACCM uniquely qualify it for studies of stratospheric sulfate <span class="hlt">aerosol</span> <span class="hlt">geoengineering</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24132201','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24132201"><span>Impacts of light shading and nutrient enrichment <span class="hlt">geo-engineering</span> approaches on the productivity of a stratified, oligotrophic ocean ecosystem.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hardman-Mountford, Nick J; Polimene, Luca; Hirata, Takafumi; Brewin, Robert J W; Aiken, Jim</p> <p>2013-12-06</p> <p><span class="hlt">Geo-engineering</span> proposals to mitigate global warming have focused either on methods of carbon dioxide removal, particularly nutrient fertilization of plant growth, or on cooling the Earth's surface by reducing incoming solar radiation (shading). Marine phytoplankton contribute half the Earth's biological carbon fixation and carbon export in the ocean is modulated by the actions of microbes and grazing communities in recycling nutrients. Both nutrients and light are essential for photosynthesis, so understanding the relative influence of both these <span class="hlt">geo-engineering</span> approaches on ocean ecosystem production and processes is critical to the evaluation of their effectiveness. In this paper, we investigate the relationship between light and nutrient availability on productivity in a stratified, oligotrophic subtropical ocean ecosystem using a one-dimensional water column model coupled to a multi-plankton ecosystem model, with the goal of elucidating potential impacts of these <span class="hlt">geo-engineering</span> approaches on ecosystem production. We find that solar shading approaches can redistribute productivity in the water column but do not change total production. Macronutrient enrichment is able to enhance the export of carbon, although heterotrophic recycling reduces the efficiency of carbon export substantially over time. Our results highlight the requirement for a fuller consideration of marine ecosystem interactions and feedbacks, beyond simply the stimulation of surface blooms, in the evaluation of putative <span class="hlt">geo-engineering</span> approaches.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3808547','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3808547"><span>Impacts of light shading and nutrient enrichment <span class="hlt">geo-engineering</span> approaches on the productivity of a stratified, oligotrophic ocean ecosystem</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hardman-Mountford, Nick J.; Polimene, Luca; Hirata, Takafumi; Brewin, Robert J. W.; Aiken, Jim</p> <p>2013-01-01</p> <p><span class="hlt">Geo-engineering</span> proposals to mitigate global warming have focused either on methods of carbon dioxide removal, particularly nutrient fertilization of plant growth, or on cooling the Earth's surface by reducing incoming solar radiation (shading). Marine phytoplankton contribute half the Earth's biological carbon fixation and carbon export in the ocean is modulated by the actions of microbes and grazing communities in recycling nutrients. Both nutrients and light are essential for photosynthesis, so understanding the relative influence of both these <span class="hlt">geo-engineering</span> approaches on ocean ecosystem production and processes is critical to the evaluation of their effectiveness. In this paper, we investigate the relationship between light and nutrient availability on productivity in a stratified, oligotrophic subtropical ocean ecosystem using a one-dimensional water column model coupled to a multi-plankton ecosystem model, with the goal of elucidating potential impacts of these <span class="hlt">geo-engineering</span> approaches on ecosystem production. We find that solar shading approaches can redistribute productivity in the water column but do not change total production. Macronutrient enrichment is able to enhance the export of carbon, although heterotrophic recycling reduces the efficiency of carbon export substantially over time. Our results highlight the requirement for a fuller consideration of marine ecosystem interactions and feedbacks, beyond simply the stimulation of surface blooms, in the evaluation of putative <span class="hlt">geo-engineering</span> approaches. PMID:24132201</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27039034','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27039034"><span>Editorial - A critical perspective on <span class="hlt">geo-engineering</span> for eutrophication management in lakes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lürling, Miquel; Mackay, Eleanor; Reitzel, Kasper; Spears, Bryan M</p> <p>2016-06-15</p> <p>Eutrophication is the primary worldwide water quality issue. Reducing excessive external nutrient loading is the most straightforward action in mitigating eutrophication, but lakes, ponds and reservoirs often show little, if any, signs of recovery in the years following external load reduction. This is due to internal cycling of phosphorus (P). <span class="hlt">Geo-engineering</span>, which we can here define as activities intervening with biogeochemical cycles to control eutrophication in inland waters, represents a promising approach, under appropriate conditions, to reduce P release from bed sediments and cyanobacteria accumulation in surface waters, thereby speeding up recovery. In this overview, we draw on evidence from this special issue <span class="hlt">Geoengineering</span> in Lakes, and on supporting literature to provide a critical perspective on the approach. We demonstrate that many of the strong P sorbents in the literature will not be applicable in the field because of costs and other constraints. Aluminium and lanthanum modified compounds are among the most effective compounds for targeting P. Flocculants and ballast compounds can be used to sink cyanobacteria, in the short term. We emphasize that the first step in managing eutrophication is a system analysis that will reveal the main water and P flows and the biological structure of the waterbody. These site specific traits can be significant confounding factors dictating successful eutrophication management. <span class="hlt">Geo-engineering</span> techniques, considered collectively, as part of a tool kit, may ensure successful management of eutrophication through a range of target effects. In addition, novel developments in modified zeolites offer simultaneous P and nitrogen control. To facilitate research and reduce the delay from concept to market a multi-national centre of excellence is required. Copyright © 2016 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1390443-could-geoengineering-research-help-answer-one-biggest-questions-climate-science-geoengineering-research','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1390443-could-geoengineering-research-help-answer-one-biggest-questions-climate-science-geoengineering-research"><span>Could <span class="hlt">geoengineering</span> research help answer one of the biggest questions in climate science?: <span class="hlt">GEOENGINEERING</span> RESEARCH</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Wood, Robert; Ackerman, Thomas; Rasch, Philip J.; ...</p> <p>2017-06-22</p> <p>Anthropogenic <span class="hlt">aerosol</span> impacts on clouds constitute the largest source of uncertainty in quantifying the radiative forcing of climate, and hinders our ability to determine Earth's climate sensitivity to greenhouse gas increases. Representation of aerosol–cloud interactions in global models is particularly challenging because these interactions occur on typically unresolved scales. Observational studies show influences of <span class="hlt">aerosol</span> on clouds, but correlations between <span class="hlt">aerosol</span> and clouds are insufficient to constrain <span class="hlt">aerosol</span> forcing because of the difficulty in separating <span class="hlt">aerosol</span> and meteorological impacts. In this commentary, we argue that this current impasse may be overcome with the development of approaches to conduct control experimentsmore » whereby <span class="hlt">aerosol</span> particle perturbations can be introduced into patches of marine low clouds in a systematic manner. Such cloud perturbation experiments constitute a fresh approach to climate science and would provide unprecedented data to untangle the effects of <span class="hlt">aerosol</span> particles on cloud microphysics and the resulting reflection of solar radiation by clouds. Here, the control experiments would provide a critical test of high-resolution models that are used to develop an improved representation aerosol–cloud interactions needed to better constrain <span class="hlt">aerosol</span> forcing in global climate models.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1390443','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1390443"><span>Could <span class="hlt">geoengineering</span> research help answer one of the biggest questions in climate science?: <span class="hlt">GEOENGINEERING</span> RESEARCH</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Wood, Robert; Ackerman, Thomas; Rasch, Philip J.</p> <p></p> <p>Anthropogenic <span class="hlt">aerosol</span> impacts on clouds constitute the largest source of uncertainty in quantifying the radiative forcing of climate, and hinders our ability to determine Earth's climate sensitivity to greenhouse gas increases. Representation of aerosol–cloud interactions in global models is particularly challenging because these interactions occur on typically unresolved scales. Observational studies show influences of <span class="hlt">aerosol</span> on clouds, but correlations between <span class="hlt">aerosol</span> and clouds are insufficient to constrain <span class="hlt">aerosol</span> forcing because of the difficulty in separating <span class="hlt">aerosol</span> and meteorological impacts. In this commentary, we argue that this current impasse may be overcome with the development of approaches to conduct control experimentsmore » whereby <span class="hlt">aerosol</span> particle perturbations can be introduced into patches of marine low clouds in a systematic manner. Such cloud perturbation experiments constitute a fresh approach to climate science and would provide unprecedented data to untangle the effects of <span class="hlt">aerosol</span> particles on cloud microphysics and the resulting reflection of solar radiation by clouds. Here, the control experiments would provide a critical test of high-resolution models that are used to develop an improved representation aerosol–cloud interactions needed to better constrain <span class="hlt">aerosol</span> forcing in global climate models.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1818403O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1818403O"><span>Fractals for <span class="hlt">Geoengineering</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oleshko, Klaudia; de Jesús Correa López, María; Romero, Alejandro; Ramírez, Victor; Pérez, Olga</p> <p>2016-04-01</p> <p>The effectiveness of fractal toolbox to capture the scaling or fractal probability distribution, and simply fractal statistics of main hydrocarbon reservoir attributes, was highlighted by Mandelbrot (1995) and confirmed by several researchers (Zhao et al., 2015). Notwithstanding, after more than twenty years, it's still common the opinion that fractals are not useful for the petroleum engineers and especially for <span class="hlt">Geoengineering</span> (Corbett, 2012). In spite of this negative background, we have successfully applied the fractal and multifractal techniques to our project entitled "Petroleum Reservoir as a Fractal Reactor" (2013 up to now). The distinguishable feature of Fractal Reservoir is the irregular shapes and rough pore/solid distributions (Siler, 2007), observed across a broad range of scales (from SEM to seismic). At the beginning, we have accomplished the detailed analysis of Nelson and Kibler (2003) Catalog of Porosity and Permeability, created for the core plugs of siliciclastic rocks (around ten thousand data were compared). We enriched this Catalog by more than two thousand data extracted from the last ten years publications on PoroPerm (Corbett, 2012) in carbonates deposits, as well as by our own data from one of the PEMEX, Mexico, oil fields. The strong power law scaling behavior was documented for the major part of these data from the geological deposits of contrasting genesis. Based on these results and taking into account the basic principles and models of the Physics of Fractals, introduced by Per Back and Kan Chen (1989), we have developed new software (Muukíl Kaab), useful to process the multiscale geological and geophysical information and to integrate the static geological and petrophysical reservoir models to dynamic ones. The new type of fractal numerical model with dynamical power law relations among the shapes and sizes of mesh' cells was designed and calibrated in the studied area. The statistically sound power law relations were established</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A52E..01D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A52E..01D"><span>Links Between the Oxidation of Glyoxal and Sulfur Dioxide, the Production of Brown Carbon, and <span class="hlt">Geoengineering</span> Schemes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Haan, D. O.; Sueme, W. R.; Rynaski, A.; Torkelson, A.; Czer, E. T.</p> <p>2012-12-01</p> <p>A correlation between oxalic acid and sulfate in atmospheric <span class="hlt">aerosol</span> was reported by J. Z. Yu et al. in 2005. It was suggested that this correlation could be explained by the dominance of in-cloud oxidation pathways forming both species from their major precursors, SO2 and glyoxal. The chemistry of these two precursors is linked via the rapid, reversible formation of an adduct molecule reported by Olson and Hoffmann in 1988. We show that at pH > 4, the oxidation of solutions containing both sulfite ions and glyoxal generates a series of redox-active quinones that absorb visible light. Using LCMS in negative ion mode, we quantify the formation of the colored compounds tetrahydroquinone, rhodizonic acid, and croconic acid (CrA) in glyoxal + bisulfite aqueous reaction mixtures as a function of pH. Of these three compounds, CrA would be expected to have the longest lifetime in the atmosphere. Ultimately, the same oxidation products are formed as when SO2 and glyoxal are oxidized separately (e.g. sulfate, oxalate, malonic acid). There are no other reported colored compounds in the oxidation series after CrA. However, comparisons between LCMS and UV-Vis absorbance measurements indicate that even after the three known colored compounds have oxidized, glyoxal / bisulfite reaction samples remain yellow for many days. This suggests the production of additional, unknown compounds that absorb visible light. These experiments show that the linked oxidation of glyoxal and SO2 in clouds and aqueous <span class="hlt">aerosol</span> is capable of producing brown carbon. This process has the potential to reduce the effectiveness of proposed <span class="hlt">geoengineering</span> schemes where SO2 would be intentionally added to the atmosphere in order to cool the planet by increasing the planetary albedo through sulfate <span class="hlt">aerosol</span> formation. The presence of glyoxal in the atmosphere (produced from the oxidation of biogenic gases) could partially cancel the desired cooling effect due to the unintended production of brown carbon</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ACPD...10.7421J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ACPD...10.7421J"><span><span class="hlt">Geoengineering</span> by stratospheric SO2 injection: results from the Met Office HadGEM2 climate model and comparison with the Goddard Institute for Space Studies ModelE</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jones, A.; Haywood, J.; Boucher, O.; Kravitz, B.; Robock, A.</p> <p>2010-03-01</p> <p>We examine the response of the Met Office Hadley Centre's HadGEM2-AO climate model to simulated <span class="hlt">geoengineering</span> by continuous injection of SO2 into the lower stratosphere, and compare the results with those from the Goddard Institute for Space Studies ModelE. The HadGEM2 simulations suggest that the SO2 injection rate considered here (5 Tg[SO2] yr-1) could defer the amount of global warming predicted under the Intergovernmental Panel on Climate Change's A1B scenario by approximately 30-35 years, although both models indicate rapid warming if <span class="hlt">geoengineering</span> is not sustained. We find a broadly similar geographic distribution of the response to <span class="hlt">geoengineering</span> in both models in terms of near-surface air temperature and mean June-August precipitation. The simulations also suggest that significant changes in regional climate would be experienced even if <span class="hlt">geoengineering</span> was successful in maintaining global-mean temperature near current values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5753843','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5753843"><span>The international politics of <span class="hlt">geoengineering</span>: The feasibility of Plan B for tackling climate change</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Corry, Olaf</p> <p>2017-01-01</p> <p><span class="hlt">Geoengineering</span> technologies aim to make large-scale and deliberate interventions in the climate system possible. A typical framing is that researchers are exploring a ‘Plan B’ in case mitigation fails to avert dangerous climate change. Some options are thought to have the potential to alter the politics of climate change dramatically, yet in evaluating whether they might ultimately reduce climate risks, their political and security implications have so far not been given adequate prominence. This article puts forward what it calls the ‘security hazard’ and argues that this could be a crucial factor in determining whether a technology is able, ultimately, to reduce climate risks. Ideas about global governance of <span class="hlt">geoengineering</span> rely on heroic assumptions about state rationality and a generally pacific international system. Moreover, if in a climate engineered world weather events become something certain states can be made directly responsible for, this may also negatively affect prospects for ‘Plan A’, i.e. an effective global agreement on mitigation. PMID:29386754</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMGC21I..06S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMGC21I..06S"><span>Modelling Potential Consequences of Different <span class="hlt">Geo-Engineering</span> Treatments for the Baltic Sea Ecosystem</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schrum, C.; Daewel, U.</p> <p>2017-12-01</p> <p>From 1950 onwards, the Baltic Sea ecosystem suffered increasingly from eutrophication. The most obvious reason for the eutrophication is the huge amount of nutrients (nitrogen and phosphorus) reaching the Baltic Sea from human activities. However, although nutrient loads have been decreasing since 1980, the hypoxic areas have not decreased accordingly. Thus, <span class="hlt">geo-engineering</span> projects were discussed and evaluated to artificially ventilate the Baltic Sea deep water and suppress nutrient release from the sediments. Here, we aim at understanding the consequences of proposed <span class="hlt">geo-engineering</span> projects in the Baltic Sea using long-term scenario modelling. For that purpose, we utilize a 3d coupled ecosystem model ECOSMO E2E, a novel NPZD-Fish model approach that resolves hydrodynamics, biogeochemical cycling and lower and higher trophic level dynamics. We performed scenario modelling that consider proposed <span class="hlt">geo-engineering</span> projects such as artificial ventilation of Baltic Sea deep waters and phosphorus binding in sediments with polyaluminium chlorides. The model indicates that deep-water ventilation indeed suppresses phosphorus release in the first 1-4 years of treatment. Thereafter macrobenthos repopulates the formerly anoxic bottom regions and nutrients are increasingly recycled in the food web. Consequently, overall system productivity and fish biomass increases and toxic algae blooms decrease. However, deep-water ventilation has no long-lasting effect on the ecosystem: soon after completion of the ventilation process, the system turns back into its original state. Artificial phosphorus binding in sediments in contrast decreases overall ecosystem productivity through permanent removal of phosphorus. As expected it decreases bacterial production and toxic algae blooms, but it also decreases fish production substantially. Contrastingly to deep water ventilation, artificial phosphorus binding show a long-lasting effect over decades after termination of the treatment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27312332','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27312332"><span>Influence of sediment resuspension on the efficacy of <span class="hlt">geoengineering</span> materials in the control of internal phosphorous loading from shallow eutrophic lakes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yin, Hongbin; Kong, Ming; Han, Meixiang; Fan, Chengxin</p> <p>2016-12-01</p> <p>Modified clay-based solid-phase phosphorous (P) sorbents are increasingly used as lake <span class="hlt">geoengineering</span> materials for lake eutrophication control. However, some still dispute the feasibility of using these materials to control internal P loading from shallow eutrophic lakes. The lack of information about P behavior while undergoing frequent sediment resuspension greatly inhibits the modified minerals' use. In this study, a sediment resuspension generating system was used to simulate the effect of both moderate winds (5.1 m/s) and strong winds (8.7 m/s) on the stability of sediment treated by two <span class="hlt">geoengineering</span> materials, Phoslock ® (a lanthanum modified bentonite) and thermally-treated calcium-rich attapulgite. This study also presents an analysis of the P dynamics across the sediment-water interface of two shallow eutrophic lakes. In addition, the effect of wind velocity on P forms and P supply from the treated sediment were studied using chemical extraction and diffusive gradients in thin films (DGT) technique, respectively. Results showed that adding <span class="hlt">geoengineering</span> materials can enhance the stability of surface sediment and reduce the erosion depth caused by wind accordingly. All treatments can effectively reduce soluble reactive phosphorus (SRP) concentration in overlying water when sediment is capped with thermally-treated calcium-rich attapulgite, which performs better than sediment mixed with modified attapulgite but not as well as sediment treated with Phoslock ® . However, their efficiency decreased with the increase in occurrences of sediment resuspension. The addition of the selected <span class="hlt">geoengineering</span> materials effectively reduced the P fluxes across sediment-water interface and lowered P supply ability from the treated sediment during sediment resuspension. The reduction of mobile P and enhancement of calcium bound P and residual P fraction in the treated sediment was beneficial to the long-term lake internal P loading management. All of the results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/59558-geoengineering-properties-potential-repository-units-yucca-mountain-southern-nevada','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/59558-geoengineering-properties-potential-repository-units-yucca-mountain-southern-nevada"><span><span class="hlt">Geoengineering</span> properties of potential repository units at Yucca Mountain, southern Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Tillerson, J.R.; Nimick, F.B.</p> <p>1984-12-01</p> <p>The Nevada Nuclear Waste Storage Investigations (NNWSI) Project is currently evaluating volcanic tuffs at the Yucca Mountain site, located on and adjacent to the Nevada Test Site, for possible use as a host rock for a radioactive waste repository. The behavior of tuff as an engineering material must be understood to design, license, construct, and operate a repository. <span class="hlt">Geoengineering</span> evaluations and measurements are being made to develop confidence in both the analysis techniques for thermal, mechanical, and hydrothermal effects and the supporting data base of rock properties. The analysis techniques and the data base are currently used for repository design,more » waste package design, and performance assessment analyses. This report documents the data base of <span class="hlt">geoengineering</span> properties used in the analyses that aided the selection of the waste emplacement horizon and in analyses synopsized in the Environmental Assessment Report prepared for the Yucca Mountain site. The strategy used for the development of the data base relies primarily on data obtained in laboratory tests that are then confirmed in field tests. Average thermal and mechanical properties (and their anticipated variations) are presented. Based upon these data, analyses completed to date, and previous excavation experience in tuff, it is anticipated that existing mining technology can be used to develop stable underground openings and that repository operations can be carried out safely.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AMT....11.2085M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AMT....11.2085M"><span><span class="hlt">Aerosol</span> particle size distribution in the stratosphere retrieved from SCIAMACHY limb measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Malinina, Elizaveta; Rozanov, Alexei; Rozanov, Vladimir; Liebing, Patricia; Bovensmann, Heinrich; Burrows, John P.</p> <p>2018-04-01</p> <p><Information about <span class="hlt">aerosols</span> in the Earth's atmosphere is of a great importance in the scientific community. While tropospheric <span class="hlt">aerosol</span> influences the radiative balance of the troposphere and affects human health, stratospheric <span class="hlt">aerosol</span> plays an important role in atmospheric chemistry and climate change. In particular, information about the amount and distribution of stratospheric <span class="hlt">aerosols</span> is required to initialize climate models, as well as validate <span class="hlt">aerosol</span> microphysics models and investigate <span class="hlt">geoengineering</span>. In addition, good knowledge of stratospheric <span class="hlt">aerosol</span> loading is needed to increase the retrieval accuracy of key trace gases (e.g. ozone or water vapour) when interpreting remote sensing measurements of the scattered solar light. The most commonly used characteristics to describe stratospheric <span class="hlt">aerosols</span> are the <span class="hlt">aerosol</span> extinction coefficient and Ångström coefficient. However, the use of particle size distribution parameters along with the <span class="hlt">aerosol</span> number density is a more optimal approach. In this paper we present a new retrieval algorithm to obtain the particle size distribution of stratospheric <span class="hlt">aerosol</span> from space-borne observations of the scattered solar light in the limb-viewing geometry. While the mode radius and width of the <span class="hlt">aerosol</span> particle size distribution are retrieved, the <span class="hlt">aerosol</span> particle number density profile remains unchanged. The latter is justified by a lower sensitivity of the limb-scattering measurements to changes in this parameter. To our knowledge this is the first data set providing two parameters of the particle size distribution of stratospheric <span class="hlt">aerosol</span> from space-borne measurements of scattered solar light. Typically, the mode radius and w can be retrieved with an uncertainty of less than 20 %. The algorithm was successfully applied to the tropical region (20° N-20° S) for 10 years (2002-2012) of SCIAMACHY observations in limb-viewing geometry, establishing a unique data set. Analysis of this new climatology for the particle size</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EaFut...5..577L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EaFut...5..577L"><span>Relevant climate response tests for stratospheric <span class="hlt">aerosol</span> injection: A combined ethical and scientific analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lenferna, Georges Alexandre; Russotto, Rick D.; Tan, Amanda; Gardiner, Stephen M.; Ackerman, Thomas P.</p> <p>2017-06-01</p> <p>In this paper, we focus on stratospheric sulfate injection as a <span class="hlt">geoengineering</span> scheme, and provide a combined scientific and ethical analysis of climate response tests, which are a subset of outdoor tests that would seek to impose detectable and attributable changes to climate variables on global or regional scales. We assess the current state of scientific understanding on the plausibility and scalability of climate response tests. Then, we delineate a minimal baseline against which to consider whether certain climate response tests would be relevant for a deployment scenario. Our analysis shows that some climate response tests, such as those attempting to detect changes in regional climate impacts, may not be deployable in time periods relevant to realistic <span class="hlt">geoengineering</span> scenarios. This might pose significant challenges for justifying stratospheric sulfate <span class="hlt">aerosol</span> injection deployment overall. We then survey some of the major ethical challenges that proposed climate response tests face. We consider what levels of confidence would be required to ethically justify approving a proposed test; whether the consequences of tests are subject to similar questions of justice, compensation, and informed consent as full-scale deployment; and whether questions of intent and hubris are morally relevant for climate response tests. We suggest further research into laboratory-based work and modeling may help to narrow the scientific uncertainties related to climate response tests, and help inform future ethical debate. However, even if such work is pursued, the ethical issues raised by proposed climate response tests are significant and manifold.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/59518-geoengineering-characterization-welded-tuffs-from-laboratory-field-investigations','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/59518-geoengineering-characterization-welded-tuffs-from-laboratory-field-investigations"><span><span class="hlt">Geoengineering</span> characterization of welded tuffs from laboratory and field investigations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Zimmerman, R.M.; Nimick, F.B.; Board, M.P.</p> <p>1984-12-31</p> <p>Welded tuff beneath Yucca Mountain adjacent to the Nevada Test Site (NTS) is being considered for development as a high-level radioactive waste repository by the Nevada Nuclear Waste Storage Investigations (NNWSI) Project. Because access into Yucca Mountain has been limited to borehole explorations, early <span class="hlt">geoengineering</span> materials characterizations have been derived from laboratory tests on cores from Yucca Mountain and from laboratory and field tests on welded tuffs located in G-Tunnel on the NTS. G-Tunnel contains welded tuffs that have similar properties and stress states to those at Yucca Mountain and has been the location for in situ rock mechanics testing.more » The purpose of this paper is to summarize the <span class="hlt">geoengineering</span> material property data obtained to date and to compare appropriate laboratory and field data from G-Tunnel to findings from Yucca Mountain. Geomechanical and thermal data are provided and are augmented by limited geological and hydrological data. A comparison of results of laboratory measurements on tuffs from Yucca Mountain and G-Tunnel indicates good agreement between the bulk densities, saturations, moduli of elasticity, Poisson`s ratios, and P-wave velocities. The G-Tunnel tuff has slightly lower thermal conductivity, tensile strength, compressive strength and slightly higher matrix permeability than does the welded tuff near the proposed repository horizon at Yucca Mountain. From a laboratory-to-field scaling perspective, the modulus of deformation shows the most sensitivity to field conditions because of the presence of the joints found in the field. 14 references, 1 table.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/59883-geoengineering-characterization-welded-tuffs-from-laboratory-field-investigations','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/59883-geoengineering-characterization-welded-tuffs-from-laboratory-field-investigations"><span><span class="hlt">Geoengineering</span> characterization of welded tuffs from laboratory and field investigations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Zimmerman, R.M.; Nimick, F.B.; Board, M.P.</p> <p>1984-12-31</p> <p>Welded tuff beneath Yucca Mountain adjacent to the Nevada Test Site (NTS) is being considered for development as a high-level radioactive waste repository by the Nevada Nuclear Waste Storage Investigations (NNWSI) Project. Because access into Yucca Mountain has been limited to borehole explorations, early <span class="hlt">geoengineering</span> materials characterizations have been derived from laboratory tests on cores from Yucca Mountain and from laboratory and field tests on welded tuffs located in G-Tunnel on the NTS. G-Tunnel contains welded tuffs that have similar properties and stress states to those at Yucca Mountain and has been the location for in situ rock mechanics testing.more » The purpose of this paper is to summarize the <span class="hlt">geoengineering</span> material property data obtained to date and to compare appropriate laboratory and field data from G-Tunnel to findings from Yucca Mountain. Geomechanical and thermal data are provided and are augmented by limited geological and hydrological data. A comparison of results of laboratory measurements on tuffs from Yucca Mountain and G-Tunnel indicates good agreement between the bulk densities, saturations, moduli of elasticity, Poisson`s ratios, and P-wave velocities. The G-Tunnel tuff has slightly lower thermal conductivity, tensile strength, compressive strength and slightly higher matrix permeability than does the welded tuff near the proposed repository horizon at Yucca Mountain. From a laboratory-to-field scaling perspective, the modulus of deformation shows the most sensitivity to field conditions because of the presence of joints found in the field. 14 refs., 1 tab.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1347870','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1347870"><span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>MacMartin, Douglas G.; Kravitz, Ben; Long, Jane C. S.</p> <p></p> <p>Any well-informed future decision on whether and how to deploy solar <span class="hlt">geoengineering</span> requires balancing the impacts (both intended and unintended) of intervening in the climate against the impacts of not doing so. In spite of the tremendous progress in the last decade, the current state of knowledge remains insufficient to support an assessment of this balance, even for stratospheric <span class="hlt">aerosol</span> <span class="hlt">geoengineering</span> (SAG), arguably the best understood (practical) <span class="hlt">geoengineering</span> method. We then articulate key unknowns associated with SAG, including both climate-science and design questions, as an essential step toward developing a future strategic research program that could address outstanding uncertainties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1326137-geoengineering-design-problem','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1326137-geoengineering-design-problem"><span><span class="hlt">Geoengineering</span> as a design problem</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kravitz, Ben; MacMartin, Douglas G.; Wang, Hailong</p> <p>2016-01-01</p> <p>Understanding the climate impacts of solar <span class="hlt">geoengineering</span> is essential for evaluating its benefits and risks. Most previous simulations have prescribed a particular strategy and evaluated its modeled effects. Here we turn this approach around by first choosing example climate objectives and then designing a strategy to meet those objectives in climate models. There are four essential criteria for designing a strategy: (i) an explicit specification of the objectives, (ii) defining what climate forcing agents to modify so the objectives are met, (iii) a method for managing uncertainties, and (iv) independent verification of the strategy in an evaluation model. We demonstrate this design perspective throughmore » two multi-objective examples. First, changes in Arctic temperature and the position of tropical precipitation due to CO 2 increases are offset by adjusting high-latitude insolation in each hemisphere independently. Second, three different latitude-dependent patterns of insolation are modified to offset CO 2-induced changes in global mean temperature, interhemispheric temperature asymmetry, and the Equator-to-pole temperature gradient. In both examples, the "design" and "evaluation" models are state-of-the-art fully coupled atmosphere–ocean general circulation models.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EaFut...4..569H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EaFut...4..569H"><span>Solar <span class="hlt">geoengineering</span> economics: From incredible to inevitable and half-way back</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harding, Anthony; Moreno-Cruz, Juan B.</p> <p>2016-12-01</p> <p>Solar <span class="hlt">geoengineering</span> technologies are unique in many ways, and the economic incentives they could unleash are just as interesting. Since their introduction as a potential alternative, economists have been intrigued by the potential of these technologies to dramatically alter the way we think about climate policy. As our scientific understanding of the technologies evolve, so does the way economists think about them. In this paper, we document the evolution of economic thinking around these technologies since before Crutzen (2006) until today and provide some fruitful areas for further research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EaFut...4..549K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EaFut...4..549K"><span>Solar <span class="hlt">geoengineering</span> could substantially reduce climate risks—A research hypothesis for the next decade</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keith, David W.; Irvine, Peter J.</p> <p>2016-11-01</p> <p>We offer a hypothesis that if solar <span class="hlt">geoengineering</span> (SG) were deployed to offset half of the increase in global-mean temperature from the date of deployment using a technology and deployment method chosen to approximate a reduction in the solar constant then, over the 21st century, it would (a) substantially reduce the global aggregate risks of climate change, (b) without making any country worse off, and (c) with the aggregate risks from side-effects being small in comparison to the reduction in climate risks. We do not set out to demonstrate this hypothesis; rather we propose it with the goal of stimulating a strategic engagement of the SG research community with policy-relevant questions. We elaborate seven sub-hypotheses on the effects of our scenario for key risks of climate change that could be assessed in future modeling work. As an example, we provide a defence of one of our sub-hypotheses, that our scenario of SG would reduce the risk of drought in dry regions, but also identify issues that may undermine this sub-hypothesis and how future work could resolve this question. SG cannot <span class="hlt">substitute</span> for emissions mitigation but it may be a useful supplement. It is our hope that scientific and technical research over the next decade focuses more closely on well-articulated variants of the key policy-relevant question: could SG be designed and deployed in such a way that it could substantially and equitably reduce climate risks?</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1511300W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1511300W"><span>Global <span class="hlt">aerosol</span> effects on convective clouds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wagner, Till; Stier, Philip</p> <p>2013-04-01</p> <p>Atmospheric <span class="hlt">aerosols</span> affect cloud properties, and thereby the radiation balance of the planet and the water cycle. The influence of <span class="hlt">aerosols</span> on clouds is dominated by increase of cloud droplet and ice crystal numbers (CDNC/ICNC) due to enhanced <span class="hlt">aerosols</span> acting as cloud condensation and ice nuclei. In deep convective clouds this increase in CDNC/ICNC is hypothesised to increase precipitation because of cloud invigoration through enhanced freezing and associated increased latent heat release caused by delayed warm rain formation. Satellite studies robustly show an increase of cloud top height (CTH) and precipitation with increasing <span class="hlt">aerosol</span> optical depth (AOD, as proxy for <span class="hlt">aerosol</span> amount). To represent <span class="hlt">aerosol</span> effects and study their influence on convective clouds in the global climate <span class="hlt">aerosol</span> model ECHAM-HAM, we <span class="hlt">substitute</span> the standard convection parameterisation, which uses one mean convective cloud for each grid column, with the convective cloud field model (CCFM), which simulates a spectrum of convective clouds, each with distinct values of radius, mixing ratios, vertical velocity, height and en/detrainment. <span class="hlt">Aerosol</span> activation and droplet nucleation in convective updrafts at cloud base is the primary driver for microphysical <span class="hlt">aerosol</span> effects. To produce realistic estimates for vertical velocity at cloud base we use an entraining dry parcel sub cloud model which is triggered by perturbations of sensible and latent heat at the surface. <span class="hlt">Aerosol</span> activation at cloud base is modelled with a mechanistic, Köhler theory based, scheme, which couples the <span class="hlt">aerosols</span> to the convective microphysics. Comparison of relationships between CTH and AOD, and precipitation and AOD produced by this novel model and satellite based estimates show general agreement. Through model experiments and analysis of the model cloud processes we are able to investigate the main drivers for the relationship between CTH / precipitation and AOD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1130690-impact-abrupt-suspension-solar-radiation-management-termination-effect-experiment-g2-geoengineering-model-intercomparison-project-geomip','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1130690-impact-abrupt-suspension-solar-radiation-management-termination-effect-experiment-g2-geoengineering-model-intercomparison-project-geomip"><span>The Impact of Abrupt Suspension of Solar Radiation Management (Termination Effect) in Experiment G2 of the <span class="hlt">Geoengineering</span> Model Intercomparison Project (GeoMIP)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Jones, Andrew; Haywood, J.; Alterskjaer, Kari</p> <p>2013-09-11</p> <p>We have examined changes in climate which result from the sudden termination of <span class="hlt">geoengineering</span> after 50 years of offsetting a 1% per annum increase in CO2 concentra- tions as simulated by 11 different climate models in experiment G2 of the <span class="hlt">Geoengineering</span> Model Intercomparison Project. The models agree on a rapid rate of global-mean warming following termination, accompanied by increases in global-mean precipitation rate and in plant net primary productivity, and decreases in sea-ice cover. While there is a considerable degree of consensus for the geographical distribution of warming, there is much less of an agreement regarding the patterns of changemore » in the other quantities.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/971893-geoengineering-cloud-seeding-influence-sea-ice-climate-system','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/971893-geoengineering-cloud-seeding-influence-sea-ice-climate-system"><span><span class="hlt">Geoengineering</span> by cloud seeding: influence on sea ice and climate system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Rasch, Philip J.; Latham, John; Chen, Chih-Chieh</p> <p>2009-12-18</p> <p>GCM computations using a fully coupled ocean atmosphere model indicate that increasing cloud reflectivity by seeding maritime boundary layer clouds with particles made from seawater may compensate for some of the effects on climate of increasing greenhouse gas concentrations. The chosen seeding strategy (one of many possible scenarios) can restore global averages of temperature, precipitation and sea ice to present day values, but not simultaneously. The response varies nonlinearly with extent of the seeding, and <span class="hlt">geoengineering</span> generates local changes to important climatic features. The global tradeoffs of restoring ice cover and cooling the planet must be assessed alongside the localmore » changes to climate features.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1228343-geoengineering-model-intercomparison-project-phase-geomip6-simulation-design-preliminary-results','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1228343-geoengineering-model-intercomparison-project-phase-geomip6-simulation-design-preliminary-results"><span>The <span class="hlt">Geoengineering</span> Model Intercomparison Project Phase 6 (GeoMIP6): Simulation design and preliminary results</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Kravitz, Benjamin S.; Robock, Alan; Tilmes, S.; ...</p> <p>2015-10-27</p> <p>We present a suite of new climate model experiment designs for the <span class="hlt">Geoengineering</span> Model Intercomparison Project (GeoMIP). This set of experiments, named GeoMIP6 (to be consistent with the Coupled Model Intercomparison Project Phase 6), builds on the previous GeoMIP project simulations, and has been expanded to address several further important topics, including key uncertainties in extreme events, the use of <span class="hlt">geoengineering</span> as part of a portfolio of responses to climate change, and the relatively new idea of cirrus cloud thinning to allow more long wave radiation to escape to space. We discuss experiment designs, as well as the rationale formore » those designs, showing preliminary results from individual models when available. We also introduce a new feature, called the GeoMIP Testbed, which provides a platform for simulations that will be performed with a few models and subsequently assessed to determine whether the proposed experiment designs will be adopted as core (Tier 1) GeoMIP experiments. In conclusion, this is meant to encourage various stakeholders to propose new targeted experiments that address their key open science questions, with the goal of making GeoMIP more relevant to a broader set of communities.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.U43A0039R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.U43A0039R"><span>Ozone Depletion Caused by Rocket Engine Emissions: A Fundamental Limit on the Scale and Viability of Space-Based <span class="hlt">Geoengineering</span> Schemes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ross, M. N.; Toohey, D.</p> <p>2008-12-01</p> <p>Emissions from solid and liquid propellant rocket engines reduce global stratospheric ozone levels. Currently ~ one kiloton of payloads are launched into earth orbit annually by the global space industry. Stratospheric ozone depletion from present day launches is a small fraction of the ~ 4% globally averaged ozone loss caused by halogen gases. Thus rocket engine emissions are currently considered a minor, if poorly understood, contributor to ozone depletion. Proposed space-based <span class="hlt">geoengineering</span> projects designed to mitigate climate change would require order of magnitude increases in the amount of material launched into earth orbit. The increased launches would result in comparable increases in the global ozone depletion caused by rocket emissions. We estimate global ozone loss caused by three space-based <span class="hlt">geoengineering</span> proposals to mitigate climate change: (1) mirrors, (2) sunshade, and (3) space-based solar power (SSP). The SSP concept does not directly engineer climate, but is touted as a mitigation strategy in that SSP would reduce CO2 emissions. We show that launching the mirrors or sunshade would cause global ozone loss between 2% and 20%. Ozone loss associated with an economically viable SSP system would be at least 0.4% and possibly as large as 3%. It is not clear which, if any, of these levels of ozone loss would be acceptable under the Montreal Protocol. The large uncertainties are mainly caused by a lack of data or validated models regarding liquid propellant rocket engine emissions. Our results offer four main conclusions. (1) The viability of space-based <span class="hlt">geoengineering</span> schemes could well be undermined by the relatively large ozone depletion that would be caused by the required rocket launches. (2) Analysis of space- based <span class="hlt">geoengineering</span> schemes should include the difficult tradeoff between the gain of long-term (~ decades) climate control and the loss of short-term (~ years) deep ozone loss. (3) The trade can be properly evaluated only if our</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1041421-ecosystem-impacts-geoengineering-review-developing-science-plan','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1041421-ecosystem-impacts-geoengineering-review-developing-science-plan"><span>ECOSYSTEM IMPACTS OF <span class="hlt">GEOENGINEERING</span>: A Review for Developing a Science Plan</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Russell, Lynn M; Jackson, Robert B; Norby, Richard J</p> <p>2012-01-01</p> <p><span class="hlt">Geoengineering</span> methods are intended to reduce the magnitude of climate change, which is already having demonstrable effects on ecosystem structure and functioning. Two different types of activities have been proposed: solar radiation management (SRM), or sunlight reflection methods, which involves reflecting a small percentage of solar light back into space to offset the warming due to greenhouse gases, and carbon dioxide removal (CDR), which includes a range of engineered and biological processes to remove carbon dioxide (CO2) from the atmosphere. This report evaluates some of the possible impacts of CDR and SRM on the physical climate and their subsequent influencemore » on ecosystems, which include the risks and uncertainties associated with new kinds of purposeful perturbations to the Earth. Therefore, the question considered in this review is whether CDR and SRM methods would exacerbate or alleviate the deleterious impacts on ecosystems associated with climate changes that might occur in the foreseeable future.<span class="hlt">Geoengineering</span> methods are intended to reduce the magnitude of climate change, which is already having demonstrable effects on ecosystem structure and functioning. Two different types of activities have been proposed: solar radiation management (SRM), or sunlight reflection methods, which involves reflecting a small percentage of solar light back into space to offset the warming due to greenhouse gases, and carbon dioxide removal (CDR), which includes a range of engineered and biological processes to remove carbon dioxide (CO2) from the atmosphere. This report evaluates some of the possible impacts of CDR and SRM on the physical climate and their subsequent influence on ecosystems, which include the risks and uncertainties associated with new kinds of purposeful perturbations to the Earth. Therefore, the question considered in this review is whether CDR and SRM methods would exacerbate or alleviate the deleterious impacts on ecosystems associated with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGC33B1239L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGC33B1239L"><span><span class="hlt">Geoengineering</span> and the blockchain: a near-complete solution to greenhouse emissions?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lockley, A.; Coffman, D.</p> <p>2016-12-01</p> <p><span class="hlt">Geoengineering</span> has been proposed to deal partially with the consequences ofanthropogenic global warming. This is composed of two strands - fast acting,incomplete but inexpensive solar radiation management; and carbon dioxide removal,which (if enacted quickly) has the potential to be a complete solution. We propose asystem of smart contracts, executed and made transparent by the blockchain, toprovide an economically and environmentally complete solution to carbon emissions atthe point of combustion. This will integrate CDR futures contracts and SRM carboncredits to ensure that all emissions are fully and transactionally disposed of at themoment of release. Specifically, we suggest use of an SRM 'bridge' contract, tocounter the warming caused between CDR economic activity being undertaken, andthe resultant drawdown of carbon occurring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3405667','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3405667"><span>Ocean acidification in a <span class="hlt">geoengineering</span> context</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Williamson, Phillip; Turley, Carol</p> <p>2012-01-01</p> <p>Fundamental changes to marine chemistry are occurring because of increasing carbon dioxide (CO2) in the atmosphere. Ocean acidity (H+ concentration) and bicarbonate ion concentrations are increasing, whereas carbonate ion concentrations are decreasing. There has already been an average pH decrease of 0.1 in the upper ocean, and continued unconstrained carbon emissions would further reduce average upper ocean pH by approximately 0.3 by 2100. Laboratory experiments, observations and projections indicate that such ocean acidification may have ecological and biogeochemical impacts that last for many thousands of years. The future magnitude of such effects will be very closely linked to atmospheric CO2; they will, therefore, depend on the success of emission reduction, and could also be constrained by <span class="hlt">geoengineering</span> based on most carbon dioxide removal (CDR) techniques. However, some ocean-based CDR approaches would (if deployed on a climatically significant scale) re-locate acidification from the upper ocean to the seafloor or elsewhere in the ocean interior. If solar radiation management were to be the main policy response to counteract global warming, ocean acidification would continue to be driven by increases in atmospheric CO2, although with additional temperature-related effects on CO2 and CaCO3 solubility and terrestrial carbon sequestration. PMID:22869801</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19850527','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19850527"><span>Modelling effects of <span class="hlt">geoengineering</span> options in response to climate change and global warming: implications for coral reefs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Crabbe, M J C</p> <p>2009-12-01</p> <p>Climate change will have serious effects on the planet and on its ecosystems. Currently, mitigation efforts are proving ineffectual in reducing anthropogenic CO2 emissions. Coral reefs are the most sensitive ecosystems on the planet to climate change, and here we review modelling a number of <span class="hlt">geoengineering</span> options, and their potential influence on coral reefs. There are two categories of <span class="hlt">geoengineering</span>, shortwave solar radiation management and longwave carbon dioxide removal. The first set of techniques only reduce some, but not all, effects of climate change, while possibly creating other problems. They also do not affect CO2 levels and therefore fail to address the wider effects of rising CO2, including ocean acidification, important for coral reefs. Solar radiation is important to coral growth and survival, and solar radiation management is not in general appropriate for this ecosystem. Longwave carbon dioxide removal techniques address the root cause of climate change, rising CO2 concentrations, they have relatively low uncertainties and risks. They are worthy of further research and potential implementation, particularly carbon capture and storage, biochar, and afforestation methods, alongside increased mitigation of atmospheric CO2 concentrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22869797','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22869797"><span>The runaway greenhouse: implications for future climate change, <span class="hlt">geoengineering</span> and planetary atmospheres.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Goldblatt, Colin; Watson, Andrew J</p> <p>2012-09-13</p> <p>The ultimate climate emergency is a 'runaway greenhouse': a hot and water-vapour-rich atmosphere limits the emission of thermal radiation to space, causing runaway warming. Warming ceases only after the surface reaches approximately 1400 K and emits radiation in the near-infrared, where water is not a good greenhouse gas. This would evaporate the entire ocean and exterminate all planetary life. Venus experienced a runaway greenhouse in the past, and we expect that the Earth will in around 2 billion years as solar luminosity increases. But could we bring on such a catastrophe prematurely, by our current climate-altering activities? Here, we review what is known about the runaway greenhouse to answer this question, describing the various limits on outgoing radiation and how climate will evolve between these. The good news is that almost all lines of evidence lead us to believe that is unlikely to be possible, even in principle, to trigger full a runaway greenhouse by addition of non-condensible greenhouse gases such as carbon dioxide to the atmosphere. However, our understanding of the dynamics, thermodynamics, radiative transfer and cloud physics of hot and steamy atmospheres is weak. We cannot therefore completely rule out the possibility that human actions might cause a transition, if not to full runaway, then at least to a much warmer climate state than the present one. High climate sensitivity might provide a warning. If we, or more likely our remote descendants, are threatened with a runaway greenhouse, then <span class="hlt">geoengineering</span> to reflect sunlight might be life's only hope. Injecting reflective <span class="hlt">aerosols</span> into the stratosphere would be too short-lived, and even sunshades in space might require excessive maintenance. In the distant future, modifying Earth's orbit might provide a sustainable solution. The runaway greenhouse also remains relevant in planetary sciences and astrobiology: as extrasolar planets smaller and nearer to their stars are detected, some will be in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMGC43H1162K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMGC43H1162K"><span>Stratospheric controlled perturbation experiment (SCoPEx): overview, status, and results from related laboratory experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keith, D.; Dykema, J. A.; Keutsch, F. N.</p> <p>2017-12-01</p> <p>Stratospheric Controlled Perturbation Experiment (SCoPEx), is a scientific experiment to advance understanding of stratospheric <span class="hlt">aerosols</span>. It aims to make quantitative measurements of <span class="hlt">aerosol</span> microphysics and atmospheric chemistry to improve large-scale models used to assess the risks and benefits of solar <span class="hlt">geoengineering</span>. A perturbative experiment requires: (a) means to create a well-mixed, small perturbed volume, and (b) observation of time evolution of chemistry and <span class="hlt">aerosols</span> in the volume. SCoPEx will used a propelled balloon gondola containing all instruments and drive system. The propeller wake forms a well-mixed volume (roughly 1 km long and 100 meters in diameter) that serves as an experimental `beaker' into which <span class="hlt">aerosols</span> (e.g., < 1 kg of 0.3 µm radius CaCO3 particles) at can be injected; while, the propellers allow the gondola to move at speeds up to 3 m/sec relative to the local air mass driving the gondola back forth through the volume to measure properties of the perturbed air mass. This presentation will provide an overview of the experiment including (a) a systems engineering perspective from high-level scientific questions through instrument selection, mission design, and proposed operations and data analysis; (b) instruments, include current status of integration testing; (c) payload engineering including structure, power and mass budget, etc; (d) results from CFD simulation of propeller wake and simulation of chemistry and <span class="hlt">aerosol</span> microphysics; and finally (e) proposed concept of operations and schedule. We will also provide an overview of the plans for governance including management of health safety and environmental risks, transparency, public engagement, and larger questions about governance of solar <span class="hlt">geoengineering</span> experiments. Finally, we will briefly present results of laboratory experiments of the interaction of chemical such as ClONO2 and HCl on particle surfaces relevant for stratospheric solar <span class="hlt">geoengineering</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1253481','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1253481"><span>How well could existing sensors detect the deployment of a solar radiation management (SRM) <span class="hlt">geoengineering</span> effort?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Hurd, Alan J.</p> <p>2016-04-29</p> <p>While the stated reason for asking this question is “to understand better our ability to warn policy makers in the unlikely event of an unanticipated SRM <span class="hlt">geoengineering</span> deployment or large-scale field experiment”, my colleagues and I felt that motives would be important context because the scale of any meaningful SRM deployment would be so large that covert deployment seems impossible. However, several motives emerged that suggest a less-than-global effort might be important.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.2808E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.2808E"><span>A New Approach to <span class="hlt">Geoengineering</span>: Manna From Heaven</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ellery, Alex</p> <p>2015-04-01</p> <p><span class="hlt">Geo-engineering</span>, although controversial, has become an emerging factor in coping with climate change. Although most are terrestrial-based technologies, I focus on a space-based approach implemented through a solar shield system. I present several new elements that essentially render the high-cost criticism moot. Of special relevance are two seemingly unrelated technologies - the Resource Prospector Mission (RPM) to the Moon in 2018 that shall implement a technology demonstration of simple material resource extraction from lunar regolith, and the emergence of multi-material 3D printing technology that promises unprecedented robotic manufacturing capabilities. My research group has begun theoretical and experimentation work in developing the concept of a 3D printed electric motor system from lunar-type resources. The electric motor underlies every universal mechanical machine. Together with 3D printed electronics, I submit that this would enable self-replicating machines to be realised. A detailed exposition on how this may be achieved will be outlined. Such self-replicating machines could construct the spacecraft required to implement a solar shield and solar power satellites in large numbers from lunar resources with the same underlying technologies at extremely low cost.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRD..12010196G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRD..12010196G"><span>The impact of <span class="hlt">geoengineering</span> on vegetation in experiment G1 of the GeoMIP</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Glienke, Susanne; Irvine, Peter J.; Lawrence, Mark G.</p> <p>2015-10-01</p> <p>Solar Radiation Management (SRM) has been proposed as a mean to partly counteract global warming. The <span class="hlt">Geoengineering</span> Model Intercomparison Project (GeoMIP) has simulated the climate consequences of a number of SRM techniques. Thus far, the effects on vegetation have not yet been thoroughly analyzed. Here the vegetation response to the idealized GeoMIP G1 experiment from eight fully coupled Earth system models (ESMs) is analyzed, in which a reduction of the solar constant counterbalances the radiative effects of quadrupled atmospheric CO2 concentrations (abrupt4 × CO2). For most models and regions, changes in net primary productivity (NPP) are dominated by the increase in CO2, via the CO2 fertilization effect. As SRM will reduce temperatures relative to abrupt4 × CO2, in high latitudes this will offset increases in NPP. In low latitudes, this cooling relative to the abrupt4 × CO2 simulation decreases plant respiration while having little effect on gross primary productivity, thus increasing NPP. In Central America and the Mediterranean, generally dry regions which are expected to experience increased water stress with global warming, NPP is highest in the G1 experiment for all models due to the easing of water limitations from increased water use efficiency at high-CO2 concentrations and the reduced evaporative demand in a <span class="hlt">geoengineered</span> climate. The largest differences in the vegetation response are between models with and without a nitrogen cycle, with a much smaller CO2 fertilization effect for the former. These results suggest that until key vegetation processes are integrated into ESM predictions, the vegetation response to SRM will remain highly uncertain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMGC53H..01A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMGC53H..01A"><span>Why We Need to Have Broad-Based Societal Discussions of the Governance of <span class="hlt">Geoengineering</span>, at national and international levels, starting with scientists and increasingly with policy makers?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anbar, A. D.; Rowan, L. R.; Field, L. A.; Keith, D.; Robock, A.; Anbar, A. D.; van der Pluijm, B.; Pasztor, J.</p> <p>2017-12-01</p> <p>The Paris Agreement aims to limit the global temperature rise to 1.5 to 2°C above preindustrial temperature, but achieving this goal requires much higher levels of mitigation than currently planned. This challenge has focused greater attention on climate <span class="hlt">geoengineering</span> approaches, as part of an overall response starting with radical mitigation. <span class="hlt">Geoengineering</span> cannot address climate change on its own, but some scientists say that it could delay or reduce the overshoot. In so doing, we may expose the world to other serious risks. There is , however, no comprehensive international framework for governing these emerging technologies. Carbon dioxide removal technologies can have serious environmental, social and economic impacts, which need to be addressed. The largest immediate risk, however, could be the unilateral deployment of solar engineering by one country, a small group of countries, or a wealthy individual. The real or perceived impacts of deployment, including geopolitical reactions, could further destabilize a world already going through rapid change. Effective global governance frameworks could reduce this risk. SRM research is in its infancy. The real challenges are not technical, but pertain to ethics and governance. Should there be a strategic research programme, coupled with a global agreement to prohibit deployment unless and until certain risks and governance questions are adequately addressed? How would the world's governments determine if the potential global benefit of <span class="hlt">geoengineering</span> is worth the risks to certain regions? How should trans-border and trans-generational issues be addressed? How would governance frameworks withstand geopolitical changes over decades or more of deployment? How might such technologies be developed and deployed without undermining political will to cut emissions? The world is heading to an increasingly risky future and is unprepared to address the institutional and governance challenges posed by these technologies</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGC53H..01A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGC53H..01A"><span>Why We Need to Have Broad-Based Societal Discussions of the Governance of <span class="hlt">Geoengineering</span>, at national and international levels, starting with scientists and increasingly with policy makers?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anbar, A. D.; Rowan, L. R.; Field, L. A.; Keith, D.; Robock, A.; Anbar, A. D.; van der Pluijm, B.; Pasztor, J.</p> <p>2016-12-01</p> <p>The Paris Agreement aims to limit the global temperature rise to 1.5 to 2°C above preindustrial temperature, but achieving this goal requires much higher levels of mitigation than currently planned. This challenge has focused greater attention on climate <span class="hlt">geoengineering</span> approaches, as part of an overall response starting with radical mitigation. <span class="hlt">Geoengineering</span> cannot address climate change on its own, but some scientists say that it could delay or reduce the overshoot. In so doing, we may expose the world to other serious risks. There is , however, no comprehensive international framework for governing these emerging technologies. Carbon dioxide removal technologies can have serious environmental, social and economic impacts, which need to be addressed. The largest immediate risk, however, could be the unilateral deployment of solar engineering by one country, a small group of countries, or a wealthy individual. The real or perceived impacts of deployment, including geopolitical reactions, could further destabilize a world already going through rapid change. Effective global governance frameworks could reduce this risk. SRM research is in its infancy. The real challenges are not technical, but pertain to ethics and governance. Should there be a strategic research programme, coupled with a global agreement to prohibit deployment unless and until certain risks and governance questions are adequately addressed? How would the world's governments determine if the potential global benefit of <span class="hlt">geoengineering</span> is worth the risks to certain regions? How should trans-border and trans-generational issues be addressed? How would governance frameworks withstand geopolitical changes over decades or more of deployment? How might such technologies be developed and deployed without undermining political will to cut emissions? The world is heading to an increasingly risky future and is unprepared to address the institutional and governance challenges posed by these technologies</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5719884','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5719884"><span>The Role of Sulfur Dioxide in Stratospheric <span class="hlt">Aerosol</span> Formation Evaluated Using In-Situ Measurements in the Tropical Lower Stratosphere</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rollins, A. W.; Thornberry, T. D.; Watts, L. A.; Yu, P.; Rosenlof, K. H.; Mills, M.; Baumann, E.; Giorgetta, F. R.; Bui, T. V.; Höpfner, M.; Walker, K. A.; Boone, C.; Bernath, P. F.; Colarco, P. R.; Newman, P. A.; Fahey, D. W.; Gao, R. S.</p> <p>2017-01-01</p> <p>Stratospheric <span class="hlt">aerosols</span> (SAs) are a variable component of the Earth's albedo that may be intentionally enhanced in the future to offset greenhouse gases (<span class="hlt">geoengineering</span>). The role of tropospheric-sourced sulfur dioxide (SO2) in maintaining background SAs has been debated for decades without in-situ measurements of SO2 at the tropical tropopause to inform this issue. Here we clarify the role of SO2 in maintaining SAs by using new in-situ SO2 measurements to evaluate climate models and satellite retrievals. We then use the observed tropical tropopause SO2 mixing ratios to estimate the global flux of SO2 across the tropical tropopause. These analyses show that the tropopause background SO2 is about 5 times smaller than reported by the average satellite observations that have been used recently to test atmospheric models. This shifts the view of SO2 as a dominant source of SAs to a near-negligible one, possibly revealing a significant gap in the SA budget. PMID:29225384</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170010427','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170010427"><span>The Role of Sulfur Dioxide in Stratospheric <span class="hlt">Aerosol</span> Formation Evaluated Using In Situ Measurements in the Tropical Lower Stratosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rollins, A. W.; Thornberry, T. D.; Watts, L. A.; Yu, P.; Rosenlof, K. H.; Mills, M.; Baumann, E.; Girogetta, F. R.; Bui, T. V.; Hopfner, M.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170010427'); toggleEditAbsImage('author_20170010427_show'); toggleEditAbsImage('author_20170010427_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170010427_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170010427_hide"></p> <p>2017-01-01</p> <p>Stratospheric <span class="hlt">aerosols</span> (SAs) are a variable component of the Earth's albedo that may be intentionally enhanced in the future to offset greenhouse gases (<span class="hlt">geoengineering</span>). The role of tropospheric-sourced sulfur dioxide (SO2) in maintaining background SAs has been debated for decades without in-situ measurements of SO2 at the tropical tropopause to inform this issue. Here we clarify the role of SO2 in maintaining SAs by using new in-situ SO2 measurements to evaluate climate models and satellite retrievals. We then use the observed tropical tropopause SO2 mixing ratios to estimate the global flux of SO2 across the tropical tropopause. These analyses show that the tropopause background SO2 is about 5 times smaller than reported by the average satellite observations that have been used recently to test atmospheric models. This shifts the view of SO2 as a dominant source of SAs to a near-negligible one, possibly revealing a significant gap in the SA budget.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29225384','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29225384"><span>The Role of Sulfur Dioxide in Stratospheric <span class="hlt">Aerosol</span> Formation Evaluated Using In-Situ Measurements in the Tropical Lower Stratosphere.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rollins, A W; Thornberry, T D; Watts, L A; Yu, P; Rosenlof, K H; Mills, M; Baumann, E; Giorgetta, F R; Bui, T V; Höpfner, M; Walker, K A; Boone, C; Bernath, P F; Colarco, P R; Newman, P A; Fahey, D W; Gao, R S</p> <p>2017-05-16</p> <p>Stratospheric <span class="hlt">aerosols</span> (SAs) are a variable component of the Earth's albedo that may be intentionally enhanced in the future to offset greenhouse gases (<span class="hlt">geoengineering</span>). The role of tropospheric-sourced sulfur dioxide (SO 2 ) in maintaining background SAs has been debated for decades without in-situ measurements of SO 2 at the tropical tropopause to inform this issue. Here we clarify the role of SO 2 in maintaining SAs by using new in-situ SO 2 measurements to evaluate climate models and satellite retrievals. We then use the observed tropical tropopause SO 2 mixing ratios to estimate the global flux of SO 2 across the tropical tropopause. These analyses show that the tropopause background SO 2 is about 5 times smaller than reported by the average satellite observations that have been used recently to test atmospheric models. This shifts the view of SO 2 as a dominant source of SAs to a near-negligible one, possibly revealing a significant gap in the SA budget.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ERL.....8a4009K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ERL.....8a4009K"><span><span class="hlt">Geoengineering</span> impact of open ocean dissolution of olivine on atmospheric CO2, surface ocean pH and marine biology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Köhler, Peter; Abrams, Jesse F.; Völker, Christoph; Hauck, Judith; Wolf-Gladrow, Dieter A.</p> <p>2013-03-01</p> <p>Ongoing global warming induced by anthropogenic emissions has opened the debate as to whether <span class="hlt">geoengineering</span> is a ‘quick fix’ option. Here we analyse the intended and unintended effects of one specific <span class="hlt">geoengineering</span> approach, which is enhanced weathering via the open ocean dissolution of the silicate-containing mineral olivine. This approach would not only reduce atmospheric CO2 and oppose surface ocean acidification, but would also impact on marine biology. If dissolved in the surface ocean, olivine sequesters 0.28 g carbon per g of olivine dissolved, similar to land-based enhanced weathering. Silicic acid input, a byproduct of the olivine dissolution, alters marine biology because silicate is in certain areas the limiting nutrient for diatoms. As a consequence, our model predicts a shift in phytoplankton species composition towards diatoms, altering the biological carbon pumps. Enhanced olivine dissolution, both on land and in the ocean, therefore needs to be considered as ocean fertilization. From dissolution kinetics we calculate that only olivine particles with a grain size of the order of 1 μm sink slowly enough to enable a nearly complete dissolution. The energy consumption for grinding to this small size might reduce the carbon sequestration efficiency by ˜30%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EaFut...4..644R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EaFut...4..644R"><span>Albedo enhancement by stratospheric sulfur injections: More research needed</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robock, Alan</p> <p>2016-12-01</p> <p>Research on albedo enhancement by stratospheric sulfur injection inspired by Paul Crutzen's paper a decade ago has made clear that it may present serious risks and concerns as well as benefits if used to address the global warming problem. While volcanic eruptions were suggested as innocuous examples of stratospheric <span class="hlt">aerosols</span> cooling the planet, the volcano analog also argues against stratospheric <span class="hlt">geoengineering</span> because of ozone depletion and regional hydrologic responses. Continuous injection of SO2 into the lower stratosphere would reduce global warming and some of its negative impacts, and would increasing the uptake of CO2 by plants, but research in the past decade has pointed out a number of potential negative impacts of stratospheric <span class="hlt">geoengineering</span>. More research is needed to better quantify the potential benefits and risks so that if society is tempted to implement <span class="hlt">geoengineering</span> in the future it will be able to make an informed decision.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMED11B..03F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMED11B..03F"><span>Space <span class="hlt">Geoengineering</span>: James A. Van Allen's Role in Detecting and Disrupting the Magnetosphere, 1958-1962 (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fleming, J. R.</p> <p>2010-12-01</p> <p>James A. Van Allen’s celebrated discovery of Earth’s radiation belts in 1958 using Explorer 1 and 3 satellites was immediately followed by his agreement to monitor tests of nuclear weapons in space aimed at disrupting the magnetosphere. This is “space geoengineering” on a planetary scale. “Space is radioactive,” noted Van Allen’s colleague Eric Ray, and the military wanted to make it even more radioactive by nuclear detonations that, in time of war might disrupt enemy radio communications from half a world away and damage or destroy enemy intercontinental ballistic missiles. This study of Van Allen’s participation in Project Argus (1958) and Project Starfish (1962) is based on new posthumous accessions to the Van Allen Papers. At the time radio astronomers protested that, “No government has the right to change the environment in any significant way without prior international study and agreement.” Van Allen later regretted his participation in experiments that disrupted the natural magnetosphere. In a larger policy framework, the history of these space interventions and the protests they generated serve as a cautionary tale for today’s <span class="hlt">geoengineers</span> who are proposing heavy-handed manipulation of the planetary environment as a response to future climate warming. Anyone claiming that <span class="hlt">geoengineering</span> has not yet been attempted should be reminded of the planetary-scale engineering of these nukes in space. N. Christofilos describing the intended effect of the Argus nuclear explosions on the magnetosphere, which would direct a stream of radioactive particles along magnetic lines of force half a world away.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27433467','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27433467"><span>Human and Environmental Dangers Posed by Ongoing Global Tropospheric <span class="hlt">Aerosolized</span> Particulates for Weather Modification.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Herndon, J Marvin</p> <p>2016-01-01</p> <p>U.S. military perception of nuclear warfare led to countless unethical nuclear experiments performed on unsuspecting individuals without their informed consent. As evidenced here, subsequent perception of weather warfare has led to exposing millions of unsuspecting individuals to toxic coal fly ash with no public disclosure, no informed consent, and no health warnings. Three methods were used: (1) comparison of eight elements analyzed in rainwater samples, thought to have leached from <span class="hlt">aerosolized</span> coal fly ash, with corresponding coal fly ash laboratory leachate; (2) comparison of 14 elements analyzed in air filter dust with corresponding elements in coal fly ash; and (3) comparison of 23 elements analyzed in fibrous mesh found after snow melted with corresponding elements in coal fly ash. The rainwater element ratios show that the aerial particulate matter has essentially the same water-leach characteristics as coal fly ash. The air filter dust element ratios occur in the same range of compositions as coal fly ash, as do element ratios in fibrous mesh found on grass after snow melted. The fibrous mesh provides an inferred direct connection with the <span class="hlt">aerosolizing</span> jet aircraft via coal fly ash association with the jet combustion environment. Strong evidence for the correctness of the hypothesis: coal fly ash is likely the <span class="hlt">aerosolized</span> particulate emplaced in the troposphere for <span class="hlt">geoengineering</span>, weather modification, and/or climate alteration purposes. The documented public health associations for ≤2.5 μm particulate pollution are also applicable to <span class="hlt">aerosolized</span> coal fly ash. The ability of coal fly ash to release aluminum in a chemically mobile form upon exposure to water or body moisture has potentially grave human and environmental consequences over a broad spectrum, including implications for neurological diseases and biota debilitation. The ability of coal fly ash to release heavy metals and radioactive elements upon exposure to body moisture has potentially</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EaFut...5..659W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EaFut...5..659W"><span>Could <span class="hlt">geoengineering</span> research help answer one of the biggest questions in climate science?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wood, Robert; Ackerman, Thomas; Rasch, Philip; Wanser, Kelly</p> <p>2017-07-01</p> <p>Anthropogenic <span class="hlt">aerosol</span> impacts on clouds constitute the largest source of uncertainty in quantifying the radiative forcing of climate, and hinders our ability to determine Earth's climate sensitivity to greenhouse gas increases. Representation of <span class="hlt">aerosol</span>-cloud interactions in global models is particularly challenging because these interactions occur on typically unresolved scales. Observational studies show influences of <span class="hlt">aerosol</span> on clouds, but correlations between <span class="hlt">aerosol</span> and clouds are insufficient to constrain <span class="hlt">aerosol</span> forcing because of the difficulty in separating <span class="hlt">aerosol</span> and meteorological impacts. In this commentary, we argue that this current impasse may be overcome with the development of approaches to conduct control experiments whereby <span class="hlt">aerosol</span> particle perturbations can be introduced into patches of marine low clouds in a systematic manner. Such cloud perturbation experiments constitute a fresh approach to climate science and would provide unprecedented data to untangle the effects of <span class="hlt">aerosol</span> particles on cloud microphysics and the resulting reflection of solar radiation by clouds. The control experiments would provide a critical test of high-resolution models that are used to develop an improved representation <span class="hlt">aerosol</span>-cloud interactions needed to better constrain <span class="hlt">aerosol</span> forcing in global climate models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMGC13C1103M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMGC13C1103M"><span>Coalitions to engineer the climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moreno-Cruz, J. B.; Ricke, K.; Caldeira, K.</p> <p>2012-12-01</p> <p>Solar <span class="hlt">geoengineering</span> is the deliberate reduction of the amount of incoming solar radiation absorbed by Earth's climate system with the aim of reducing impacts of anthropogenic climate change. The international politics of solar <span class="hlt">geoengineering</span> differ markedly from those of greenhouse-gas emissions reductions. A central question is who will decide whether and how much solar <span class="hlt">geoengineering</span> will be deployed. It is unlikely that a single small actor could implement and sustain global-scale <span class="hlt">geoengineering</span> that harms much of the world without intervention from harmed world powers. Thus, in practice, some minimum amount of aggregate power would be needed to successfully impose will upon the rest of the world. Here we formulate a series of games, calibrated with physical and economic models of climate change, to evaluate how international coalitions to implement <span class="hlt">geoengineering</span> may form. In the scenarios examined, climate models are assumed to correctly predict the future and damage is parameterized in terms of regional temperature and precipitation changes only, and do not consider other, possibly formidable, risks. The coalitions set the "global thermostat" to maximize benefit to coalition members. As a result, non-members would be better off under a global optimum solution, but would be worse off with no <span class="hlt">geoengineering</span> at all. Nonetheless, it appears unlikely that solar <span class="hlt">geoengineering</span> could be implemented by actors who are perceived in advance to be harming the interests of a majority of the world's powers.; Comparison of results under a globally optimal versus >50% military-spending power coalition over 6 decades of solar <span class="hlt">geoengineering</span> implementation. (a) shows how the amount of solar <span class="hlt">geoengineering</span> (in units of stratospheric <span class="hlt">aerosol</span> optical depth, AOD) implemented by a Power Proportionate Distribution coalition under a military-spending-weighted power scheme (dotted), compared to the amount that minimizes net global damages (thick grey) (the population and GDP</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ERL.....4d5101.','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ERL.....4d5101."><span>INTRODUCTION: Focus on Climate Engineering: Intentional Intervention in the Climate System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p></p> <p>2009-12-01</p> <p><span class="hlt">Geoengineering</span> techniques for countering climate change have been receiving much press recently as a `Plan B' if a global deal to tackle climate change is not agreed at the COP15 negotiations in Copenhagen this December. However, the field is controversial as the methods may have unforeseen consequences, potentially making temperatures rise in some regions or reducing rainfall, and many aspects remain under-researched. This focus issue of Environmental Research Letters is a collection of research articles, invited by David Keith, University of Calgary, and Ken Caldeira, Carnegie Institution, that present and evaluate different methods for engineering the Earth's climate. Not only do the letters in this issue highlight various methods of climate engineering but they also detail the arguments for and against climate engineering as a concept. Further reading Focus on <span class="hlt">Geoengineering</span> at http://environmentalresearchweb.org/cws/subject/tag=<span class="hlt">geoengineering</span> IOP Conference Series: Earth and Environmental Science is an open-access proceedings service available at www.iop.org/EJ/journal/ees Focus on Climate Engineering: Intentional Intervention in the Climate System Contents Modification of cirrus clouds to reduce global warming David L Mitchell and William Finnegan Climate engineering and the risk of rapid climate change Andrew Ross and H Damon Matthews Researching <span class="hlt">geoengineering</span>: should not or could not? Martin Bunzl Of mongooses and mitigation: ecological analogues to <span class="hlt">geoengineering</span> H Damon Matthews and Sarah E Turner Toward ethical norms and institutions for climate engineering research David R Morrow, Robert E Kopp and Michael Oppenheimer On the possible use of <span class="hlt">geoengineering</span> to moderate specific climate change impacts Michael C MacCracken The impact of <span class="hlt">geoengineering</span> <span class="hlt">aerosols</span> on stratospheric temperature and ozone P Heckendorn, D Weisenstein, S Fueglistaler, B P Luo, E Rozanov, M Schraner, L W Thomason and T Peter The fate of the Greenland Ice Sheet in a <span class="hlt">geoengineered</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMGC43H1154W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMGC43H1154W"><span>Can <span class="hlt">Geoengineering</span> Effectively Reduce the Land Warming?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, W.; MacMartin, D.; Moore, J. C.; Ji, D.</p> <p>2017-12-01</p> <p>Permafrost, defined as ground that remains at or below 0 C for two or more consecutive years, underlies 24% of the land in the Northern Hemisphere. Under recent climate warming, permafrost has begun to thaw, causing changes in ecosystems and impacting northern communities. Using the multiple land model output from the Permafrost Carbon Network and applying 5 commonly used permafrost diagnostic methods, we assess the projected Northern Hemisphere permafrost area under RCP 8.5 scenario. Both the air and soil relative warming change is compared to highlight the soil warming pattern and intensity. Using the multiple Earth System Models output under abrupt 4×CO2, G1, PI-control, G3, G4, and RCP4.5 experiments, a preliminary attempt is also performed to examine the effectiveness of <span class="hlt">geoengineering</span> schemes on reducing the land warming. Although there is uncertainty in the projected results due to model and method difference, the soil temperature based methods derived permafrost all present an intense decrease by 48% - 68% until 2100. The projected soil temperature by the more physically complicated model shows a different warming pattern compared with the air, which indicates that some potential land process intervene with the land response to atmospheric change. The simulated soil temperature can be effectively cooled down by 2 - 9 degree under G1 compared with abrupt 4×CO2, and by less than 4 degree under G3 and G4 compared with RCP4.5.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1815332M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1815332M"><span><span class="hlt">Aerosol</span> typing - key information from <span class="hlt">aerosol</span> studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mona, Lucia; Kahn, Ralph; Papagiannopoulos, Nikolaos; Holzer-Popp, Thomas; Pappalardo, Gelsomina</p> <p>2016-04-01</p> <p><span class="hlt">Aerosol</span> typing is a key source of <span class="hlt">aerosol</span> information from ground-based and satellite-borne instruments. Depending on the specific measurement technique, <span class="hlt">aerosol</span> typing can be used as input for retrievals or represents an output for other applications. Typically <span class="hlt">aerosol</span> retrievals require some a priori or external <span class="hlt">aerosol</span> type information. The accuracy of the derived <span class="hlt">aerosol</span> products strongly depends on the reliability of these assumptions. Different sensors can make use of different <span class="hlt">aerosol</span> type inputs. A critical review and harmonization of these procedures could significantly reduce related uncertainties. On the other hand, satellite measurements in recent years are providing valuable information about the global distribution of <span class="hlt">aerosol</span> types, showing for example the main source regions and typical transport paths. Climatological studies of <span class="hlt">aerosol</span> load at global and regional scales often rely on inferred <span class="hlt">aerosol</span> type. There is still a high degree of inhomogeneity among satellite <span class="hlt">aerosol</span> typing schemes, which makes the use different sensor datasets in a consistent way difficult. Knowledge of the 4d <span class="hlt">aerosol</span> type distribution at these scales is essential for understanding the impact of different <span class="hlt">aerosol</span> sources on climate, precipitation and air quality. All this information is needed for planning upcoming <span class="hlt">aerosol</span> emissions policies. The exchange of expertise and the communication among satellite and ground-based measurement communities is fundamental for improving long-term dataset consistency, and for reducing <span class="hlt">aerosol</span> type distribution uncertainties. <span class="hlt">Aerosol</span> typing has been recognized as one of its high-priority activities of the AEROSAT (International Satellite <span class="hlt">Aerosol</span> Science Network, http://aero-sat.org/) initiative. In the AEROSAT framework, a first critical review of <span class="hlt">aerosol</span> typing procedures has been carried out. The review underlines the high heterogeneity in many aspects: approach, nomenclature, assumed number of components and parameters used for the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1184927-hydrological-sensitivity-global-warming-solar-geoengineering-derived-from-thermodynamic-constraints','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1184927-hydrological-sensitivity-global-warming-solar-geoengineering-derived-from-thermodynamic-constraints"><span>The Hydrological Sensitivity to Global Warming and Solar <span class="hlt">Geoengineering</span> Derived from Thermodynamic Constraints</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kleidon, Alex; Kravitz, Benjamin S.; Renner, Maik</p> <p>2015-01-16</p> <p>We derive analytic expressions of the transient response of the hydrological cycle to surface warming from an extremely simple energy balance model in which turbulent heat fluxes are constrained by the thermodynamic limit of maximum power. For a given magnitude of steady-state temperature change, this approach predicts the transient response as well as the steady-state change in surface energy partitioning and the hydrologic cycle. We show that the transient behavior of the simple model as well as the steady state hydrological sensitivities to greenhouse warming and solar <span class="hlt">geoengineering</span> are comparable to results from simulations using highly complex models. Many ofmore » the global-scale hydrological cycle changes can be understood from a surface energy balance perspective, and our thermodynamically-constrained approach provides a physically robust way of estimating global hydrological changes in response to altered radiative forcing.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24601011','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24601011"><span>Aqueous <span class="hlt">aerosol</span> SOA formation: impact on <span class="hlt">aerosol</span> physical properties.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Woo, Joseph L; Kim, Derek D; Schwier, Allison N; Li, Ruizhi; McNeill, V Faye</p> <p>2013-01-01</p> <p>Organic chemistry in <span class="hlt">aerosol</span> water has recently been recognized as a potentially important source of secondary organic <span class="hlt">aerosol</span> (SOA) material. This SOA material may be surface-active, therefore potentially affecting <span class="hlt">aerosol</span> heterogeneous activity, ice nucleation, and CCN activity. Aqueous <span class="hlt">aerosol</span> chemistry has also been shown to be a potential source of light-absorbing products ("brown carbon"). We present results on the formation of secondary organic <span class="hlt">aerosol</span> material in <span class="hlt">aerosol</span> water and the associated changes in <span class="hlt">aerosol</span> physical properties from GAMMA (Gas-<span class="hlt">Aerosol</span> Model for Mechanism Analysis), a photochemical box model with coupled gas and detailed aqueous <span class="hlt">aerosol</span> chemistry. The detailed <span class="hlt">aerosol</span> composition output from GAMMA was coupled with two recently developed modules for predicting a) <span class="hlt">aerosol</span> surface tension and b) the UV-Vis absorption spectrum of the <span class="hlt">aerosol</span>, based on our previous laboratory observations. The simulation results suggest that the formation of oligomers and organic acids in bulk <span class="hlt">aerosol</span> water is unlikely to perturb <span class="hlt">aerosol</span> surface tension significantly. Isoprene-derived organosulfates are formed in high concentrations in acidic <span class="hlt">aerosols</span> under low-NO(x) conditions, but more experimental data are needed before the potential impact of these species on <span class="hlt">aerosol</span> surface tension may be evaluated. Adsorption of surfactants from the gas phase may further suppress <span class="hlt">aerosol</span> surface tension. Light absorption by aqueous <span class="hlt">aerosol</span> SOA material is driven by dark glyoxal chemistry and is highest under high-NO(x) conditions, at high relative humidity, in the early morning hours. The wavelength dependence of the predicted absorption spectra is comparable to field observations and the predicted mass absorption efficiencies suggest that aqueous <span class="hlt">aerosol</span> chemistry can be a significant source of <span class="hlt">aerosol</span> brown carbon under urban conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E1492K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E1492K"><span><span class="hlt">Aerosol</span> algorithm evaluation within <span class="hlt">aerosol</span>-CCI</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kinne, Stefan; Schulz, Michael; Griesfeller, Jan</p> <p></p> <p>Properties of <span class="hlt">aerosol</span> retrievals from space are difficult. Even data from dedicated satellite sensors face contaminations which limit the accuracy of <span class="hlt">aerosol</span> retrieval products. Issues are the identification of complete cloud-free scenes, the need to assume <span class="hlt">aerosol</span> compositional features in an underdetermined solution space and the requirement to characterize the background at high accuracy. Usually the development of <span class="hlt">aerosol</span> is a slow process, requiring continuous feedback from evaluations. To demonstrate maturity, these evaluations need to cover different regions and seasons and many different <span class="hlt">aerosol</span> properties, because <span class="hlt">aerosol</span> composition is quite diverse and highly variable in space and time, as atmospheric <span class="hlt">aerosol</span> lifetimes are only a few days. Three years ago the ESA Climate Change Initiative started to support <span class="hlt">aerosol</span> retrieval efforts in order to develop <span class="hlt">aerosol</span> retrieval products for the climate community from underutilized ESA satellite sensors. The initial focus was on retrievals of AOD (a measure for the atmospheric column amount) and of Angstrom (a proxy for <span class="hlt">aerosol</span> size) from the ATSR and MERIS sensors on ENVISAT. The goal was to offer retrieval products that are comparable or better in accuracy than commonly used NASA products of MODIS or MISR. Fortunately, accurate reference data of ground based sun-/sky-photometry networks exist. Thus, retrieval assessments could and were conducted independently by different evaluation groups. Here, results of these evaluations for the year 2008 are summarized. The capability of these newly developed retrievals is analyzed and quantified in scores. These scores allowed a ranking of competing efforts and also allow skill comparisons of these new retrievals against existing and commonly used retrievals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EaFut...4..562R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EaFut...4..562R"><span>Five solar <span class="hlt">geoengineering</span> tropes that have outstayed their welcome</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reynolds, Jesse L.; Parker, Andy; Irvine, Peter</p> <p>2016-12-01</p> <p>In the last decade, solar <span class="hlt">geoengineering</span> (solar radiation management, or SRM) has received increasing consideration as a potential means to reduce risks of anthropogenic climate change. Some ideas regarding SRM that have been proposed have receded after being appropriately scrutinized, while others have strengthened through testing and critique. This process has improved the understanding of SRM's potential and limitations. However, several claims are frequently made in the academic and popular SRM discourses and, despite evidence to the contrary, pose the risk of hardening into accepted facts. Here, in order to foster a more productive and honest debate, we identify, describe, and refute five of the most problematic claims that are unsupported by existing evidence, unlikely to occur, or greatly exaggerated. These are: (A) once started, SRM cannot be stopped; (B) SRM is a right-wing project; (C) SRM would cost only a few billion dollars per year; (D) modeling studies indicate that SRM would disrupt monsoon precipitation; and (E) there is an international prohibition on outdoors research. SRM is a controversial proposed set of technologies that could prove to be very helpful or very harmful, and it warrants vigorous and informed public debate. By highlighting and debunking some persistent but unsupported claims, this paper hopes to bring rigor to such discussions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22869805','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22869805"><span>Peatland <span class="hlt">geoengineering</span>: an alternative approach to terrestrial carbon sequestration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Freeman, Christopher; Fenner, Nathalie; Shirsat, Anil H</p> <p>2012-09-13</p> <p>Terrestrial and oceanic ecosystems contribute almost equally to the sequestration of ca 50 per cent of anthropogenic CO(2) emissions, and already play a role in minimizing our impact on Earth's climate. On land, the majority of the sequestered carbon enters soil carbon stores. Almost one-third of that soil carbon can be found in peatlands, an area covering just 2-3% of the Earth's landmass. Peatlands are thus well established as powerful agents of carbon capture and storage; the preservation of archaeological artefacts, such as ancient bog bodies, further attest to their exceptional preservative properties. Peatlands have higher carbon storage densities per unit ecosystem area than either the oceans or dry terrestrial systems. However, despite attempts over a number of years at enhancing carbon capture in the oceans or in land-based afforestation schemes, no attempt has yet been made to optimize peatland carbon storage capacity or even to harness peatlands to store externally captured carbon. Recent studies suggest that peatland carbon sequestration is due to the inhibitory effects of phenolic compounds that create an 'enzymic latch' on decomposition. Here, we propose to harness that mechanism in a series of peatland <span class="hlt">geoengineering</span> strategies whereby molecular, biogeochemical, agronomical and afforestation approaches increase carbon capture and long-term sequestration in peat-forming terrestrial ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26293204','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26293204"><span>Enhanced marine sulphur emissions offset global warming and impact rainfall.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grandey, B S; Wang, C</p> <p>2015-08-21</p> <p>Artificial fertilisation of the ocean has been proposed as a possible <span class="hlt">geoengineering</span> method for removing carbon dioxide from the atmosphere. The associated increase in marine primary productivity may lead to an increase in emissions of dimethyl sulphide (DMS), the primary source of sulphate <span class="hlt">aerosol</span> over remote ocean regions, potentially causing direct and cloud-related indirect <span class="hlt">aerosol</span> effects on climate. This pathway from ocean fertilisation to <span class="hlt">aerosol</span> induced cooling of the climate may provide a basis for solar radiation management (SRM) <span class="hlt">geoengineering</span>. In this study, we investigate the transient climate impacts of two emissions scenarios: an RCP4.5 (Representative Concentration Pathway 4.5) control; and an idealised scenario, based on RCP4.5, in which DMS emissions are substantially enhanced over ocean areas. We use mini-ensembles of a coupled atmosphere-ocean configuration of CESM1(CAM5) (Community Earth System Model version 1, with the Community Atmosphere Model version 5). We find that the cooling effect associated with enhanced DMS emissions beneficially offsets greenhouse gas induced warming across most of the world. However, the rainfall response may adversely affect water resources, potentially impacting human livelihoods. These results demonstrate that changes in marine phytoplankton activity may lead to a mixture of positive and negative impacts on the climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4543957','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4543957"><span>Enhanced marine sulphur emissions offset global warming and impact rainfall</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Grandey, B. S.; Wang, C.</p> <p>2015-01-01</p> <p>Artificial fertilisation of the ocean has been proposed as a possible <span class="hlt">geoengineering</span> method for removing carbon dioxide from the atmosphere. The associated increase in marine primary productivity may lead to an increase in emissions of dimethyl sulphide (DMS), the primary source of sulphate <span class="hlt">aerosol</span> over remote ocean regions, potentially causing direct and cloud-related indirect <span class="hlt">aerosol</span> effects on climate. This pathway from ocean fertilisation to <span class="hlt">aerosol</span> induced cooling of the climate may provide a basis for solar radiation management (SRM) <span class="hlt">geoengineering</span>. In this study, we investigate the transient climate impacts of two emissions scenarios: an RCP4.5 (Representative Concentration Pathway 4.5) control; and an idealised scenario, based on RCP4.5, in which DMS emissions are substantially enhanced over ocean areas. We use mini-ensembles of a coupled atmosphere-ocean configuration of CESM1(CAM5) (Community Earth System Model version 1, with the Community Atmosphere Model version 5). We find that the cooling effect associated with enhanced DMS emissions beneficially offsets greenhouse gas induced warming across most of the world. However, the rainfall response may adversely affect water resources, potentially impacting human livelihoods. These results demonstrate that changes in marine phytoplankton activity may lead to a mixture of positive and negative impacts on the climate. PMID:26293204</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...513055G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...513055G"><span>Enhanced marine sulphur emissions offset global warming and impact rainfall</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grandey, B. S.; Wang, C.</p> <p>2015-08-01</p> <p>Artificial fertilisation of the ocean has been proposed as a possible <span class="hlt">geoengineering</span> method for removing carbon dioxide from the atmosphere. The associated increase in marine primary productivity may lead to an increase in emissions of dimethyl sulphide (DMS), the primary source of sulphate <span class="hlt">aerosol</span> over remote ocean regions, potentially causing direct and cloud-related indirect <span class="hlt">aerosol</span> effects on climate. This pathway from ocean fertilisation to <span class="hlt">aerosol</span> induced cooling of the climate may provide a basis for solar radiation management (SRM) <span class="hlt">geoengineering</span>. In this study, we investigate the transient climate impacts of two emissions scenarios: an RCP4.5 (Representative Concentration Pathway 4.5) control; and an idealised scenario, based on RCP4.5, in which DMS emissions are substantially enhanced over ocean areas. We use mini-ensembles of a coupled atmosphere-ocean configuration of CESM1(CAM5) (Community Earth System Model version 1, with the Community Atmosphere Model version 5). We find that the cooling effect associated with enhanced DMS emissions beneficially offsets greenhouse gas induced warming across most of the world. However, the rainfall response may adversely affect water resources, potentially impacting human livelihoods. These results demonstrate that changes in marine phytoplankton activity may lead to a mixture of positive and negative impacts on the climate.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ACPD...1531973N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ACPD...1531973N"><span>Ozone changes under solar <span class="hlt">geoengineering</span>: implications for UV exposure and air quality</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nowack, P. J.; Abraham, N. L.; Braesicke, P.; Pyle, J. A.</p> <p>2015-11-01</p> <p>Various forms of <span class="hlt">geoengineering</span> have been proposed to counter anthropogenic climate change. Methods which aim to modify the Earth's energy balance by reducing insolation are often subsumed under the term Solar Radiation Management (SRM). Here, we present results of a standard SRM modelling experiment in which the incoming solar irradiance is reduced to offset the global mean warming induced by a quadrupling of atmospheric carbon dioxide. For the first time in an atmosphere-ocean coupled climate model, we include atmospheric composition feedbacks such as ozone changes under this scenario. Including the composition changes, we find large reductions in surface UV-B irradiance, with implications for vitamin D production, and increases in surface ozone concentrations, both of which could be important for human health. We highlight that both tropospheric and stratospheric ozone changes should be considered in the assessment of any SRM scheme, due to their important roles in regulating UV exposure and air quality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29882781','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29882781"><span><span class="hlt">Aerosol</span> Synthesis of N and N-S Doped and Crumpled Graphene Nanostructures.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carraro, Francesco; Cattelan, Mattia; Favaro, Marco; Calvillo, Laura</p> <p>2018-06-06</p> <p>Chemically modified graphene⁻based materials (CMG) are currently attracting a vast interest in their application in different fields. In particular, heteroatom-doped graphenes have revealed great potentialities in the field of electrocatalysis as <span class="hlt">substitutes</span> of fuel cell noble metal⁻based catalysts. In this work, we investigate an innovative process for doping graphene nanostructures. We optimize a novel synthetic route based on <span class="hlt">aerosol</span> preparation, which allows the simultaneous doping, crumpling, and reduction of graphene oxide (GO). Starting from aqueous solutions containing GO and the dopant precursors, we synthesize N- and N,S-dual-doped 3D graphene nanostructures (N-cGO and N,S-cGO). In the <span class="hlt">aerosol</span> process, every <span class="hlt">aerosol</span> droplet can be considered as a microreactor where dopant precursors undergo thermal decomposition and react with the GO flakes. Simultaneously, thanks to the relatively high temperature, GO undergoes crumpling and partial reduction. Using a combination of spectroscopic and microscopic characterization techniques, we investigate the morphology of the obtained materials and the chemical nature of the dopants within the crumpled graphene sheets. This study highlights the versatility of the <span class="hlt">aerosol</span> process for the design of new CMG materials with tailored electrocatalytic properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSHI14A1762H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSHI14A1762H"><span>Saving Humanity from Catastrophic Cooling with <span class="hlt">Geo-Engineering</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haapala, K.; Singer, S. F.</p> <p>2016-02-01</p> <p>There are two kinds of ice ages; they are fundamentally different and therefore require different methods of mitigation: (i) Major (Milankovitch-style) glaciations occur on a 100,000-year time-scale and are controlled astronomically. (ii) "Little" ice ages were discovered in ice cores; they have been occurring on an approx. 1000-1500-yr cycle and are likely controlled by the Sun [Ref: Singer & Avery 2007. Unstoppable Global Warming: Every 1500 years]. The current cycle's cooling phase may be imminent - hence there may be urgent need for action. To stop onset of a major (Milankovitch) glaciation 1. Locate a "trigger" - a growing perennial snow/ice field - using satellites 2. Spread soot, to lower the albedo, and use Sun to melt 3. How much soot? How to apply soot? Learn by experimentation To lessen (regional, intermittent) cooling of DOB (Dansgaard-Oeschger-Bond) cycles1. Use greenhouse effect of manmade cirrus (ice particles) [Ref: Singer 1988. Meteorology and Atmospheric Physics 38:228 - 239]2. Inject water droplets (mist) near tropopause 3. Trace dispersion of cirrus cloud by satellite and observe warming at surface 4. How much water; over what area? How often to inject? Learn by experimentation Many scientific questions remain. While certainly interesting and important, there is really no need to delay the crucial and urgent tests of <span class="hlt">geo-engineering</span>, designed to validate schemes of mitigation. Such proposed tests involve only minor costs and present negligible risks to the environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ACP....1712097S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ACP....1712097S"><span>Classifying <span class="hlt">aerosol</span> type using in situ surface spectral <span class="hlt">aerosol</span> optical properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmeisser, Lauren; Andrews, Elisabeth; Ogren, John A.; Sheridan, Patrick; Jefferson, Anne; Sharma, Sangeeta; Kim, Jeong Eun; Sherman, James P.; Sorribas, Mar; Kalapov, Ivo; Arsov, Todor; Angelov, Christo; Mayol-Bracero, Olga L.; Labuschagne, Casper; Kim, Sang-Woo; Hoffer, András; Lin, Neng-Huei; Chia, Hao-Ping; Bergin, Michael; Sun, Junying; Liu, Peng; Wu, Hao</p> <p>2017-10-01</p> <p>Knowledge of <span class="hlt">aerosol</span> size and composition is important for determining radiative forcing effects of <span class="hlt">aerosols</span>, identifying <span class="hlt">aerosol</span> sources and improving <span class="hlt">aerosol</span> satellite retrieval algorithms. The ability to extrapolate <span class="hlt">aerosol</span> size and composition, or type, from intensive <span class="hlt">aerosol</span> optical properties can help expand the current knowledge of spatiotemporal variability in <span class="hlt">aerosol</span> type globally, particularly where chemical composition measurements do not exist concurrently with optical property measurements. This study uses medians of the scattering Ångström exponent (SAE), absorption Ångström exponent (AAE) and single scattering albedo (SSA) from 24 stations within the NOAA/ESRL Federated <span class="hlt">Aerosol</span> Monitoring Network to infer <span class="hlt">aerosol</span> type using previously published <span class="hlt">aerosol</span> classification schemes.Three methods are implemented to obtain a best estimate of dominant <span class="hlt">aerosol</span> type at each station using <span class="hlt">aerosol</span> optical properties. The first method plots station medians into an AAE vs. SAE plot space, so that a unique combination of intensive properties corresponds with an <span class="hlt">aerosol</span> type. The second typing method expands on the first by introducing a multivariate cluster analysis, which aims to group stations with similar optical characteristics and thus similar dominant <span class="hlt">aerosol</span> type. The third and final classification method pairs 3-day backward air mass trajectories with median <span class="hlt">aerosol</span> optical properties to explore the relationship between trajectory origin (proxy for likely <span class="hlt">aerosol</span> type) and <span class="hlt">aerosol</span> intensive parameters, while allowing for multiple dominant <span class="hlt">aerosol</span> types at each station.The three <span class="hlt">aerosol</span> classification methods have some common, and thus robust, results. In general, estimating dominant <span class="hlt">aerosol</span> type using optical properties is best suited for site locations with a stable and homogenous <span class="hlt">aerosol</span> population, particularly continental polluted (carbonaceous <span class="hlt">aerosol</span>), marine polluted (carbonaceous <span class="hlt">aerosol</span> mixed with sea salt) and continental dust/biomass sites</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol31/pdf/CFR-2014-title40-vol31-sec721-981.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol31/pdf/CFR-2014-title40-vol31-sec721-981.pdf"><span>40 CFR 721.981 - <span class="hlt">Substituted</span> naphtholoazo-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex. 721.981 Section 721.981 Protection of Environment...-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex. (a) Chemical substance and significant new... naphtholoazo-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex (PMN P-93-1631) is subject to...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol32/pdf/CFR-2013-title40-vol32-sec721-981.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol32/pdf/CFR-2013-title40-vol32-sec721-981.pdf"><span>40 CFR 721.981 - <span class="hlt">Substituted</span> naphtholoazo-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex. 721.981 Section 721.981 Protection of Environment...-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex. (a) Chemical substance and significant new... naphtholoazo-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex (PMN P-93-1631) is subject to...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol32/pdf/CFR-2012-title40-vol32-sec721-981.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol32/pdf/CFR-2012-title40-vol32-sec721-981.pdf"><span>40 CFR 721.981 - <span class="hlt">Substituted</span> naphtholoazo-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex. 721.981 Section 721.981 Protection of Environment...-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex. (a) Chemical substance and significant new... naphtholoazo-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex (PMN P-93-1631) is subject to...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol31/pdf/CFR-2011-title40-vol31-sec721-981.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol31/pdf/CFR-2011-title40-vol31-sec721-981.pdf"><span>40 CFR 721.981 - <span class="hlt">Substituted</span> naphtholoazo-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex. 721.981 Section 721.981 Protection of Environment...-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex. (a) Chemical substance and significant new... naphtholoazo-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex (PMN P-93-1631) is subject to...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRG..121....2T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRG..121....2T"><span>Impact of idealized future stratospheric <span class="hlt">aerosol</span> injection on the large-scale ocean and land carbon cycles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tjiputra, J. F.; Grini, A.; Lee, H.</p> <p>2016-01-01</p> <p>Using an Earth system model, we simulate stratospheric <span class="hlt">aerosol</span> injection (SAI) on top of the Representative Concentration Pathways 8.5 future scenario. Our idealized method prescribes <span class="hlt">aerosol</span> concentration, linearly increasing from 2020 to 2100, and thereafter remaining constant until 2200. In the aggressive scenario, the model projects a cooling trend toward 2100 despite warming that persists in the high latitudes. Following SAI termination in 2100, a rapid global warming of 0.35 K yr-1 is simulated in the subsequent 10 years, and the global mean temperature returns to levels close to the reference state, though roughly 0.5 K cooler. In contrast to earlier findings, we show a weak response in the terrestrial carbon sink during SAI implementation in the 21st century, which we attribute to nitrogen limitation. The SAI increases the land carbon uptake in the temperate forest-, grassland-, and shrub-dominated regions. The resultant lower temperatures lead to a reduction in the heterotrophic respiration rate and increase soil carbon retention. Changes in precipitation patterns are key drivers for variability in vegetation carbon. Upon SAI termination, the level of vegetation carbon storage returns to the reference case, whereas the soil carbon remains high. The ocean absorbs nearly 10% more carbon in the <span class="hlt">geoengineered</span> simulation than in the reference simulation, leading to a ˜15 ppm lower atmospheric CO2 concentration in 2100. The largest enhancement in uptake occurs in the North Atlantic. In both hemispheres' polar regions, SAI delays the sea ice melting and, consequently, export production remains low. In the deep water of North Atlantic, SAI-induced circulation changes accelerate the ocean acidification rate and broaden the affected area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1198289-multiday-production-condensing-organic-aerosol-mass-urban-forest-outflow','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1198289-multiday-production-condensing-organic-aerosol-mass-urban-forest-outflow"><span>Multiday production of condensing organic <span class="hlt">aerosol</span> mass in urban and forest outflow</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Lee-Taylor, J.; Hodzic, A.; Madronich, S.; ...</p> <p>2014-07-03</p> <p>Secondary organic <span class="hlt">aerosol</span> (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for several days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (∼50%) and of shorter duration (1–2 days). The production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction products ofmore » both aromatics and alkanes. In particular we find large contributions from <span class="hlt">substituted</span> maleic anhydrides and multi-<span class="hlt">substituted</span> peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic <span class="hlt">aerosol</span> precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26726845','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26726845"><span>First Quantification of Imidazoles in Ambient <span class="hlt">Aerosol</span> Particles: Potential Photosensitizers, Brown Carbon Constituents, and Hazardous Components.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Teich, Monique; van Pinxteren, Dominik; Kecorius, Simonas; Wang, Zhibin; Herrmann, Hartmut</p> <p>2016-02-02</p> <p>Imidazoles are widely discussed in recent literature. They have been studied as a secondary product of the reaction of dicarbonyls with nitrogen containing compounds in a number of laboratory studies, potentially acting as photosensitizers triggering secondary organic <span class="hlt">aerosol</span> growth and are forming constituents of light absorbing brown carbon. Despite the knowledge from laboratory studies, no quantitative information about imidazoles in ambient <span class="hlt">aerosol</span> particles is available. Within the present study, five imidazoles (1-butylimidazole, 1-ethylimidazole, 2-ethylimidazole, imidazol-2-carboxaldehyde, and 4(5)-methylimidazole) were successfully identified and quantified for the first time in ambient <span class="hlt">aerosol</span> samples from different environments in Europe and China. Their concentrations range between 0.2 and 14 ng/m(3). 4(5)-Methylimidazole was found to be the most abundant imidazole. The occurrence of imidazoles seems to be favored at sites with strong biomass burning influence or connected to more polluted air masses. No connection was found between <span class="hlt">aerosol</span> particle pH and imidazole concentration. Our work corroborates the laboratory studies by showing that imidazoles are present in ambient <span class="hlt">aerosol</span> samples in measurable amounts. Moreover, it further motivates to explore the potential photosensitizing properties of small alkyl-<span class="hlt">substituted</span> imidazoles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ERL.....5c1001R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ERL.....5c1001R"><span>PERSPECTIVE: Technical fixes and climate change: optimizing for risks and consequences</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rasch, Philip J.</p> <p>2010-09-01</p> <p>-day values. There is a tradeoff between cooling the planet and consequences to the hydrologic cycle and sea ice cover in the Arctic. Ban-Weiss and Caldeira (2010) have taken another step in this exploration. They have treated <span class="hlt">geoengineering</span> as an optimization problem and searched for an optimal solution by varying one aspect of a <span class="hlt">geoengineering</span> methodology, imposing differences in the spatial location of the geoengineering—contrasting changes concentrated in polar regions with spatially uniform <span class="hlt">aerosol</span> distributions (i.e. shielding the poles to protect the sea ice may have a different impact on the planet than shielding an equatorial region). They measured the impact by looking at the root mean square difference between the <span class="hlt">geoengineered</span> world and present-day precipitation and temperature (as opposed to the global averaged changes in the Rasch et al study). They found that broad fixed location <span class="hlt">geoengineering</span> is quite a crude mechanism for control of temperature and precipitation. Differences between uniform and optimal <span class="hlt">geoengineering</span> distributions are quite modest, and the tradeoffs found in earlier studies are also found here. Solutions that minimize differences from present-day temperatures are not the best solutions in terms of differences in present-day precipitation. The study is simple and idealized. The measures of desirability of climate to optimize for can be made more comprehensive, including other variables or measures, for example, of transient variability (seasonal, diurnal variability, or frequency of extreme events), and it is easy to identify ways to make the <span class="hlt">geoengineering</span> strategy much more complex. The study is thought provoking, delivers clear and useful messages, outlines a methodology and helps to clarify ways to think about <span class="hlt">geoengineering</span> consequences. References Ban-Weiss G A and Caldeira K 2010 <span class="hlt">Geoengineering</span> as an optimization problem Environ. Res. Lett. 5 034009 Crutzen P J 2006 Albedo enhancement by stratospheric sulfur injections: a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ACPD...1432177B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ACPD...1432177B"><span>Using the OMI <span class="hlt">Aerosol</span> Index and Absorption <span class="hlt">Aerosol</span> Optical Depth to evaluate the NASA MERRA <span class="hlt">Aerosol</span> Reanalysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buchard, V.; da Silva, A. M.; Colarco, P. R.; Darmenov, A.; Randles, C. A.; Govindaraju, R.; Torres, O.; Campbell, J.; Spurr, R.</p> <p>2014-12-01</p> <p>A radiative transfer interface has been developed to simulate the UV <span class="hlt">Aerosol</span> Index (AI) from the NASA Goddard Earth Observing System version 5 (GEOS-5) <span class="hlt">aerosol</span> assimilated fields. The purpose of this work is to use the AI and <span class="hlt">Aerosol</span> Absorption Optical Depth (AAOD) derived from the Ozone Monitoring Instrument (OMI) measurements as independent validation for the Modern Era Retrospective analysis for Research and Applications <span class="hlt">Aerosol</span> Reanalysis (MERRAero). MERRAero is based on a version of the GEOS-5 model that is radiatively coupled to the Goddard Chemistry, <span class="hlt">Aerosol</span>, Radiation, and Transport (GOCART) <span class="hlt">aerosol</span> module and includes assimilation of <span class="hlt">Aerosol</span> Optical Depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Since AI is dependent on <span class="hlt">aerosol</span> concentration, optical properties and altitude of the <span class="hlt">aerosol</span> layer, we make use of complementary observations to fully diagnose the model, including AOD from the Multi-angle Imaging SpectroRadiometer (MISR), <span class="hlt">aerosol</span> retrievals from the <span class="hlt">Aerosol</span> Robotic Network (AERONET) and attenuated backscatter coefficients from the Cloud-<span class="hlt">Aerosol</span> Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission to ascertain potential misplacement of plume height by the model. By sampling dust, biomass burning and pollution events in 2007 we have compared model produced AI and AAOD with the corresponding OMI products, identifying regions where the model representation of absorbing <span class="hlt">aerosols</span> was deficient. As a result of this study over the Saharan dust region, we have obtained a new set of dust <span class="hlt">aerosol</span> optical properties that retains consistency with the MODIS AOD data that were assimilated, while resulting in better agreement with <span class="hlt">aerosol</span> absorption measurements from OMI. The analysis conducted over the South African and South American biomass burning regions indicates that revising the spectrally-dependent <span class="hlt">aerosol</span> absorption properties in the near-UV region improves the modeled-observed AI comparisons</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ACP....15.5743B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ACP....15.5743B"><span>Using the OMI <span class="hlt">aerosol</span> index and absorption <span class="hlt">aerosol</span> optical depth to evaluate the NASA MERRA <span class="hlt">Aerosol</span> Reanalysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buchard, V.; da Silva, A. M.; Colarco, P. R.; Darmenov, A.; Randles, C. A.; Govindaraju, R.; Torres, O.; Campbell, J.; Spurr, R.</p> <p>2015-05-01</p> <p>A radiative transfer interface has been developed to simulate the UV <span class="hlt">aerosol</span> index (AI) from the NASA Goddard Earth Observing System version 5 (GEOS-5) <span class="hlt">aerosol</span> assimilated fields. The purpose of this work is to use the AI and <span class="hlt">aerosol</span> absorption optical depth (AAOD) derived from the Ozone Monitoring Instrument (OMI) measurements as independent validation for the Modern Era Retrospective analysis for Research and Applications <span class="hlt">Aerosol</span> Reanalysis (MERRAero). MERRAero is based on a version of the GEOS-5 model that is radiatively coupled to the Goddard Chemistry, <span class="hlt">Aerosol</span>, Radiation, and Transport (GOCART) <span class="hlt">aerosol</span> module and includes assimilation of <span class="hlt">aerosol</span> optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Since AI is dependent on <span class="hlt">aerosol</span> concentration, optical properties and altitude of the <span class="hlt">aerosol</span> layer, we make use of complementary observations to fully diagnose the model, including AOD from the Multi-angle Imaging SpectroRadiometer (MISR), <span class="hlt">aerosol</span> retrievals from the <span class="hlt">AErosol</span> RObotic NETwork (AERONET) and attenuated backscatter coefficients from the Cloud-<span class="hlt">Aerosol</span> Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission to ascertain potential misplacement of plume height by the model. By sampling dust, biomass burning and pollution events in 2007 we have compared model-produced AI and AAOD with the corresponding OMI products, identifying regions where the model representation of absorbing <span class="hlt">aerosols</span> was deficient. As a result of this study over the Saharan dust region, we have obtained a new set of dust <span class="hlt">aerosol</span> optical properties that retains consistency with the MODIS AOD data that were assimilated, while resulting in better agreement with <span class="hlt">aerosol</span> absorption measurements from OMI. The analysis conducted over the southern African and South American biomass burning regions indicates that revising the spectrally dependent <span class="hlt">aerosol</span> absorption properties in the near-UV region improves the modeled-observed AI comparisons</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120003705','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120003705"><span>Informing <span class="hlt">Aerosol</span> Transport Models With Satellite Multi-Angle <span class="hlt">Aerosol</span> Measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Limbacher, J.; Patadia, F.; Petrenko, M.; Martin, M. Val; Chin, M.; Gaitley, B.; Garay, M.; Kalashnikova, O.; Nelson, D.; Scollo, S.</p> <p>2011-01-01</p> <p>As the <span class="hlt">aerosol</span> products from the NASA Earth Observing System's Multi-angle Imaging SpectroRadiometer (MISR) mature, we are placing greater focus on ways of using the <span class="hlt">aerosol</span> amount and type data products, and <span class="hlt">aerosol</span> plume heights, to constrain <span class="hlt">aerosol</span> transport models. We have demonstrated the ability to map <span class="hlt">aerosol</span> air-mass-types regionally, and have identified product upgrades required to apply them globally, including the need for a quality flag indicating the <span class="hlt">aerosol</span> type information content, that varies depending upon retrieval conditions. We have shown that MISR <span class="hlt">aerosol</span> type can distinguish smoke from dust, volcanic ash from sulfate and water particles, and can identify qualitative differences in mixtures of smoke, dust, and pollution <span class="hlt">aerosol</span> components in urban settings. We demonstrated the use of stereo imaging to map smoke, dust, and volcanic effluent plume injection height, and the combination of MISR and MODIS <span class="hlt">aerosol</span> optical depth maps to constrain wildfire smoke source strength. This talk will briefly highlight where we stand on these application, with emphasis on the steps we are taking toward applying the capabilities toward constraining <span class="hlt">aerosol</span> transport models, planet-wide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A23F0399D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A23F0399D"><span>Biology of the Coarse <span class="hlt">Aerosol</span> Mode: Insights Into Urban <span class="hlt">Aerosol</span> Ecology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dueker, E.; O'Mullan, G. D.; Montero, A.</p> <p>2015-12-01</p> <p>Microbial <span class="hlt">aerosols</span> have been understudied, despite implications for climate studies, public health, and biogeochemical cycling. Because viable bacterial <span class="hlt">aerosols</span> are often associated with coarse <span class="hlt">aerosol</span> particles, our limited understanding of the coarse <span class="hlt">aerosol</span> mode further impedes our ability to develop models of viable bacterial <span class="hlt">aerosol</span> production, transport, and fate in the outdoor environment, particularly in crowded urban centers. To address this knowledge gap, we studied <span class="hlt">aerosol</span> particle biology and size distributions in a broad range of urban and rural settings. Our previously published findings suggest a link between microbial viability and local production of coarse <span class="hlt">aerosols</span> from waterways, waste treatment facilities, and terrestrial systems in urban and rural environments. Both in coastal Maine and in New York Harbor, coarse <span class="hlt">aerosols</span> and viable bacterial <span class="hlt">aerosols</span> increased with increasing wind speeds above 4 m s-1, a dynamic that was observed over time scales ranging from minutes to hours. At a New York City superfund-designated waterway regularly contaminated with raw sewage, aeration remediation efforts resulted in significant increases of coarse <span class="hlt">aerosols</span> and bacterial <span class="hlt">aerosols</span> above that waterway. Our current research indicates that bacterial communities in <span class="hlt">aerosols</span> at this superfund site have a greater similarity to bacterial communities in the contaminated waterway with wind speeds above 4 m s-1. Size-fractionated sampling of viable microbial <span class="hlt">aerosols</span> along the urban waterfront has also revealed significant shifts in bacterial <span class="hlt">aerosols</span>, and specifically bacteria associated with coarse <span class="hlt">aerosols</span>, when wind direction changes from onshore to offshore. This research highlights the key connections between bacterial <span class="hlt">aerosol</span> viability and the coarse <span class="hlt">aerosol</span> fraction, which is important in assessments of production, transport, and fate of bacterial contamination in the urban environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.A13A0179K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.A13A0179K"><span>Measurements of Semi-volatile <span class="hlt">Aerosol</span> and Its Effect on <span class="hlt">Aerosol</span> Optical Properties During Southern Oxidant and <span class="hlt">Aerosol</span> Study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khlystov, A.; Grieshop, A. P.; Saha, P.; Subramanian, R.</p> <p>2013-12-01</p> <p>Semi-volatile compounds, including particle-bound water, comprise a large part of <span class="hlt">aerosol</span> mass and have a significant influence on <span class="hlt">aerosol</span> lifecycle and its optical properties. Understanding the properties of semi-volatile compounds, especially those pertaining to gas/<span class="hlt">aerosol</span> partitioning, is of critical importance for our ability to predict concentrations and properties of ambient <span class="hlt">aerosol</span>. A set of state-of-the-art instruments was deployed at the SEARCH site near Centerville, AL during the Southern Oxidant and <span class="hlt">Aerosol</span> Study (SOAS) campaign in summer 2013 to measure the effect of temperature and relative humidity on <span class="hlt">aerosol</span> size distribution, composition and optical properties. Light scattering and absorption by temperature- and humidity-conditioned <span class="hlt">aerosols</span> was measured using three photo-acoustic extinctiometers (PAX) at three wavelengths (405 nm, 532 nm, and 870 nm). In parallel to these measurements, a long residence time temperature-stepping thermodenuder and a variable residence time constant temperature thermodenuder in combination with three SMPS systems and an <span class="hlt">Aerosol</span> Chemical Speciation Monitor (ACSM) were used to assess <span class="hlt">aerosol</span> volatility and kinetics of <span class="hlt">aerosol</span> evaporation. It was found that both temperature and relative humidity have a strong effect on <span class="hlt">aerosol</span> optical properties. The variable residence time thermodenuder data suggest that <span class="hlt">aerosol</span> equilibrated fairly quickly, within 2 s, in contrast to other ambient observations. Preliminary analysis show that approximately 50% and 90% of total <span class="hlt">aerosol</span> mass evaporated at temperatures of 100 C and 180C, respectively. Evaporation varied substantially with ambient <span class="hlt">aerosol</span> loading and composition and meteorology. During course of this study, T50 (temperatures at which 50% <span class="hlt">aerosol</span> mass evaporates) varied from 60 C to more than 120 C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.U41E..01T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.U41E..01T"><span>Terraforming the Planets and Climate Change Mitigation on Earth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Toon, O. B.</p> <p>2008-12-01</p> <p>Hopefully, purposeful <span class="hlt">geo-engineering</span> of the Earth will remain a theoretical concept. Of course, we have already inadvertently changed the Earth, and over geologic history life has left an indelible imprint on our planet. We can learn about <span class="hlt">geo-engineering</span> schemes by reference to Earth history, for example climate changes after volcanic eruptions provide important clues to using sulfates to modify the climate. The terrestrial planets and Titan offer additional insights. For instance, Mars and Venus both have carbon dioxide dominated greenhouses. Both have more than 10 times as much carbon dioxide in their atmospheres as Earth, and both absorb less sunlight than Earth, yet one is much colder than Earth and one is much hotter. These facts provide important insights into carbon dioxide greenhouses that I will review. Mars cools dramatically following planet wide dust storms, and Titan has what is referred to as an anti- greenhouse climate driven by <span class="hlt">aerosols</span>. These data can be used to reassure us that we can model <span class="hlt">aerosol</span> caused changes to the climate of a planet, and also provide examples of <span class="hlt">aerosols</span> offsetting a gas-driven greenhouse effect. People have long considered whether we might make the other planets habitable. While most of the schemes considered belong in the realm of science fiction, it is possible that some schemes might be practical. Terraforming brings to mind a number of issues that are thought provoking, but not so politically charged as <span class="hlt">geo-engineering</span>. For example: What criteria define habitability, is it enough for people to live in isolated glass enclosures, or do we need to walk freely on the planet? Different creatures have different needs. Is a planet habitable if plants can thrive in the open, or do animals also need to be free? Are the raw materials present on any planet to make it habitable? If not, can we make the materials, or do we have to import them? Is it ethical to change a planetary climate? What if there are already primitive</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGC33C1131P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGC33C1131P"><span>Microbially mediated carbon mineralization: <span class="hlt">Geoengineering</span> a carbon-neutral mine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Power, I. M.; McCutcheon, J.; Harrison, A. L.; Wilson, S. A.; Dipple, G. M.; Southam, G.</p> <p>2013-12-01</p> <p>Ultramafic and mafic mine tailings are a potentially valuable feedstock for carbon mineralization, affording the mining industry an opportunity to completely offset their carbon emissions. Passive carbon mineralization has previously been documented at the abandoned Clinton Creek asbestos mine, and the active Diavik diamond mine and Mount Keith nickel mine, yet the majority of tailings remain unreacted. Examples of microbe-carbonate interactions at each mine suggest that biological pathways could be harnessed to promote carbon mineralization. In suitable environmental conditions, microbes can mediate geochemical processes to accelerate mineral dissolution, increase the supply of carbon dioxide (CO2), and induce carbonate precipitation, all of which may accelerate carbon mineralization. Tailings mineralogy and the availability of a CO2 point source are key considerations in designing tailings storage facilities (TSF) for optimizing carbon mineralization. We evaluate the efficacy of acceleration strategies including bioleaching, biologically induced carbonate precipitation, and heterotrophic oxidation of waste organics, as well as abiotic strategies including enhancing passive carbonation through modifying tailings management practices and use of CO2 point sources (Fig. 1). With the aim of developing carbon-neutral mines, implementation of carbon mineralization strategies into TSF design will be driven by economic incentives and public pressure for environmental sustainability in the mining industry. Figure 1. Schematic illustrating <span class="hlt">geoengineered</span> scenarios for carbon mineralization of ultramafic mine tailings. Scenarios A and B are based on non-point and point sources of CO2, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A33C3201K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A33C3201K"><span>The Effect of <span class="hlt">Aerosol</span> Hygroscopicity and Volatility on <span class="hlt">Aerosol</span> Optical Properties During Southern Oxidant and <span class="hlt">Aerosol</span> Study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khlystov, A.; Grieshop, A. P.; Saha, P.; Subramanian, R.</p> <p>2014-12-01</p> <p>Secondary organic <span class="hlt">aerosol</span> (SOA) from biogenic sources can influence optical properties of ambient <span class="hlt">aerosol</span> by altering its hygroscopicity and contributing to light absorption directly via formation of brown carbon and indirectly by enhancing light absorption by black carbon ("lensing effect"). The magnitude of these effects remains highly uncertain. A set of state-of-the-art instruments was deployed at the SEARCH site near Centerville, AL during the Southern Oxidant and <span class="hlt">Aerosol</span> Study (SOAS) campaign in summer 2013 to measure the effect of relative humidity and temperature on <span class="hlt">aerosol</span> size distribution, composition and optical properties. Light scattering and absorption by temperature- and humidity-conditioned <span class="hlt">aerosols</span> was measured using three photo-acoustic extinctiometers (PAX) at three wavelengths (405 nm, 532 nm, and 870 nm). The sample-conditioning system provided measurements at ambient RH, 10%RH ("dry"), 85%RH ("wet"), and 200 C ("TD"). In parallel to these measurements, a long residence time temperature-stepping thermodenuder (TD) and a variable residence time constant temperature TD in combination with three SMPS systems and an <span class="hlt">Aerosol</span> Chemical Speciation Monitor (ACSM) were used to assess <span class="hlt">aerosol</span> volatility and kinetics of <span class="hlt">aerosol</span> evaporation. We will present results of the on-going analysis of the collected data set. We will show that both temperature and relative humidity have a strong effect on <span class="hlt">aerosol</span> optical properties. SOA appears to increase <span class="hlt">aerosol</span> light absorption by about 10%. TD measurements suggest that <span class="hlt">aerosol</span> equilibrated fairly quickly, within 2 s. Evaporation varied substantially with ambient <span class="hlt">aerosol</span> loading and composition and meteorology.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ACP....12.8223C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ACP....12.8223C"><span>Occurrence of lower cloud albedo in ship tracks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Y.-C.; Christensen, M. W.; Xue, L.; Sorooshian, A.; Stephens, G. L.; Rasmussen, R. M.; Seinfeld, J. H.</p> <p>2012-09-01</p> <p>The concept of <span class="hlt">geoengineering</span> by marine cloud brightening is based on seeding marine stratocumulus clouds with sub-micrometer sea-salt particles to enhance the cloud droplet number concentration and cloud albedo, thereby producing a climate cooling effect. The efficacy of this as a strategy for global cooling rests on the extent to which <span class="hlt">aerosol</span>-perturbed marine clouds will respond with increased albedo. Ship tracks, quasi-linear cloud features prevalent in oceanic regions impacted by ship exhaust, are a well-known manifestation of the effect of <span class="hlt">aerosol</span> injection on marine clouds. We present here an analysis of the albedo responses in ship tracks, based on in situ aircraft measurements and three years of satellite observations of 589 individual ship tracks. It is found that the sign (increase or decrease) and magnitude of the albedo response in ship tracks depends on the mesoscale cloud structure, the free tropospheric humidity, and cloud top height. In a closed cell structure (cloud cells ringed by a perimeter of clear air), nearly 30% of ship tracks exhibited a decreased albedo. Detailed cloud responses must be accounted for in global studies of the potential efficacy of sea-spray <span class="hlt">geoengineering</span> as a means to counteract global warming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4734356','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4734356"><span>Efficacy of Face Shields Against Cough <span class="hlt">Aerosol</span> Droplets from a Cough Simulator</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lindsley, William G.; Noti, John D.; Blachere, Francoise M.; Szalajda, Jonathan V.; Beezhold, Donald H.</p> <p>2016-01-01</p> <p>Health care workers are exposed to potentially infectious airborne particles while providing routine care to coughing patients. However, much is not understood about the behavior of these <span class="hlt">aerosols</span> and the risks they pose. We used a coughing patient simulator and a breathing worker simulator to investigate the exposure of health care workers to cough <span class="hlt">aerosol</span> droplets, and to examine the efficacy of face shields in reducing this exposure. Our results showed that 0.9% of the initial burst of <span class="hlt">aerosol</span> from a cough can be inhaled by a worker 46 cm (18 inches) from the patient. During testing of an influenza-laden cough <span class="hlt">aerosol</span> with a volume median diameter (VMD) of 8.5 μm, wearing a face shield reduced the inhalational exposure of the worker by 96% in the period immediately after a cough. The face shield also reduced the surface contamination of a respirator by 97%. When a smaller cough <span class="hlt">aerosol</span> was used (VMD = 3.4 μm), the face shield was less effective, blocking only 68% of the cough and 76% of the surface contamination. In the period from 1 to 30 minutes after a cough, during which the <span class="hlt">aerosol</span> had dispersed throughout the room and larger particles had settled, the face shield reduced <span class="hlt">aerosol</span> inhalation by only 23%. Increasing the distance between the patient and worker to 183 cm (72 inches) reduced the exposure to influenza that occurred immediately after a cough by 92%. Our results show that health care workers can inhale infectious airborne particles while treating a coughing patient. Face shields can substantially reduce the short-term exposure of health care workers to large infectious <span class="hlt">aerosol</span> particles, but smaller particles can remain airborne longer and flow around the face shield more easily to be inhaled. Thus, face shields provide a useful adjunct to respiratory protection for workers caring for patients with respiratory infections. However, they cannot be used as a <span class="hlt">substitute</span> for respiratory protection when it is needed. PMID:24467190</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A53C0293L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A53C0293L"><span>Constructing An Event Based <span class="hlt">Aerosol</span> Product Under High <span class="hlt">Aerosol</span> Loading Conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Levy, R. C.; Shi, Y.; Mattoo, S.; Remer, L. A.; Zhang, J.</p> <p>2016-12-01</p> <p>High <span class="hlt">aerosol</span> loading events, such as the Indonesia's forest fire in Fall 2015 or the persistent wintertime haze near Beijing, gain tremendous interests due to their large impact on regional visibility and air quality. Understanding the optical properties of these events and further being able to simulate and predict these events are beneficial. However, it is a great challenge to consistently identify and then retrieve <span class="hlt">aerosol</span> optical depth (AOD) from passive sensors during heavy <span class="hlt">aerosol</span> events. Some reasons include:1). large differences between optical properties of high-loading <span class="hlt">aerosols</span> and those under normal conditions, 2) spectral signals of optically thick <span class="hlt">aerosols</span> can be mistaken with surface depending on <span class="hlt">aerosol</span> types, and 3) Extremely optically thick <span class="hlt">aerosol</span> plumes can also be misidentified as clouds due to its high optical thickness. Thus, even under clear-sky conditions, the global distribution of extreme <span class="hlt">aerosol</span> events is not well captured in datasets such as the MODIS Dark-Target (DT) <span class="hlt">aerosol</span> product. In this study, with the synthetic use of OMI <span class="hlt">Aerosol</span> Index, MODIS cloud product, and operational DT product, the heavy smoke events over the seven sea region are identified and retrieved over the dry season. An event based <span class="hlt">aerosol</span> product that would compensate the standard "global" <span class="hlt">aerosol</span> retrieval will be created and evaluated. The impact of missing high AOD retrievals on the regional <span class="hlt">aerosol</span> climatology will be studied using this newly developed research product.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1197838-multiday-production-condensing-organic-aerosol-mass-urban-forest-outflow','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1197838-multiday-production-condensing-organic-aerosol-mass-urban-forest-outflow"><span>Multiday production of condensing organic <span class="hlt">aerosol</span> mass in urban and forest outflow</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Lee-Taylor, J.; Hodzic, A.; Madronich, S.</p> <p>2015-01-16</p> <p>Secondary organic <span class="hlt">aerosol</span> (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for multiple days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (~50%) and of shorter duration (1–2 days). The multiday production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction productsmore » of both aromatics and alkanes, especially those with relatively low carbon numbers (C4–15). In particular we find large contributions from <span class="hlt">substituted</span> maleic anhydrides and multi-<span class="hlt">substituted</span> peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions and different vapor pressure schemes, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic <span class="hlt">aerosol</span> precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1197838-multiday-production-condensing-organic-aerosol-mass-urban-forest-outflow','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1197838-multiday-production-condensing-organic-aerosol-mass-urban-forest-outflow"><span>Multiday production of condensing organic <span class="hlt">aerosol</span> mass in urban and forest outflow</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Lee-Taylor, J.; Hodzic, A.; Madronich, S.; ...</p> <p>2015-01-16</p> <p>Secondary organic <span class="hlt">aerosol</span> (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for multiple days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (~50%) and of shorter duration (1–2 days). The multiday production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction productsmore » of both aromatics and alkanes, especially those with relatively low carbon numbers (C4–15). In particular we find large contributions from <span class="hlt">substituted</span> maleic anhydrides and multi-<span class="hlt">substituted</span> peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions and different vapor pressure schemes, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. Here, the results imply that anthropogenic <span class="hlt">aerosol</span> precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1913909P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1913909P"><span>Imaging <span class="hlt">aerosol</span> viscosity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pope, Francis; Athanasiadis, Thanos; Botchway, Stan; Davdison, Nicholas; Fitzgerald, Clare; Gallimore, Peter; Hosny, Neveen; Kalberer, Markus; Kuimova, Marina; Vysniauskas, Aurimas; Ward, Andy</p> <p>2017-04-01</p> <p>Organic <span class="hlt">aerosol</span> particles play major roles in atmospheric chemistry, climate, and public health. <span class="hlt">Aerosol</span> particle viscosity is important since it can determine the ability of chemical species such as oxidants, organics or water to diffuse into the particle bulk. Recent measurements indicate that OA may be present in highly viscous states; however, diffusion rates of small molecules such as water appear not to be limited by these high viscosities. We have developed a technique for measuring viscosity that allows for the imaging of <span class="hlt">aerosol</span> viscosity in micron sized <span class="hlt">aerosols</span> through use of fluorescence lifetime imaging of viscosity sensitive dyes which are also known as 'molecular rotors'. These rotors can be introduced into laboratory generated <span class="hlt">aerosol</span> by adding minute quantities of the rotor to <span class="hlt">aerosol</span> precursor prior to <span class="hlt">aerosolization</span>. Real world <span class="hlt">aerosols</span> can also be studied by doping them in situ with the rotors. The doping is achieved through generation of ultrafine <span class="hlt">aerosol</span> particles that contain the rotors; the ultrafine <span class="hlt">aerosol</span> particles deliver the rotors to the <span class="hlt">aerosol</span> of interest via impaction and coagulation. This work has been conducted both on <span class="hlt">aerosols</span> deposited on microscope coverslips and on particles that are levitated in their true <span class="hlt">aerosol</span> phase through the use of a bespoke optical trap developed at the Central Laser Facility. The technique allows for the direct observation of kinetic barriers caused by high viscosity and low diffusivity in <span class="hlt">aerosol</span> particles. The technique is non-destructive thereby allowing for multiple experiments to be carried out on the same sample. It can dynamically quantify and track viscosity changes during atmospherically relevant processes such oxidation and hygroscopic growth (1). This presentation will focus on the oxidation of <span class="hlt">aerosol</span> particles composed of unsaturated and saturated organic species. It will discuss how the type of oxidant, oxidation rate and the composition of the oxidized products affect the time</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110015299','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110015299"><span>Identifying <span class="hlt">Aerosol</span> Type/Mixture from <span class="hlt">Aerosol</span> Absorption Properties Using AERONET</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Giles, D. M.; Holben, B. N.; Eck, T. F.; Sinyuk, A.; Dickerson, R. R.; Thompson, A. M.; Slutsker, I.; Li, Z.; Tripathi, S. N.; Singh, R. P.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20110015299'); toggleEditAbsImage('author_20110015299_show'); toggleEditAbsImage('author_20110015299_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20110015299_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20110015299_hide"></p> <p>2010-01-01</p> <p><span class="hlt">Aerosols</span> are generated in the atmosphere through anthropogenic and natural mechanisms. These sources have signatures in the <span class="hlt">aerosol</span> optical and microphysical properties that can be used to identify the <span class="hlt">aerosol</span> type/mixture. Spectral <span class="hlt">aerosol</span> absorption information (absorption Angstrom exponent; AAE) used in conjunction with the particle size parameterization (extinction Angstrom exponent; EAE) can only identify the dominant absorbing <span class="hlt">aerosol</span> type in the sample volume (e.g., black carbon vs. iron oxides in dust). This AAE/EAE relationship can be expanded to also identify non-absorbing <span class="hlt">aerosol</span> types/mixtures by applying an absorption weighting. This new relationship provides improved <span class="hlt">aerosol</span> type distinction when the magnitude of absorption is not equal (e.g, black carbon vs. sulfates). The <span class="hlt">Aerosol</span> Robotic Network (AERONET) data provide spectral <span class="hlt">aerosol</span> optical depth and single scattering albedo - key parameters used to determine EAE and AAE. The proposed <span class="hlt">aerosol</span> type/mixture relationship is demonstrated using the long-term data archive acquired at AERONET sites within various source regions. The preliminary analysis has found that dust, sulfate, organic carbon, and black carbon <span class="hlt">aerosol</span> types/mixtures can be determined from this AAE/EAE relationship when applying the absorption weighting for each available wavelength (Le., 440, 675, 870nm). Large, non-spherical dust particles absorb in the shorter wavelengths and the application of 440nm wavelength absorption weighting produced the best particle type definition. Sulfate particles scatter light efficiently and organic carbon particles are small near the source and aggregate over time to form larger less absorbing particles. Both sulfates and organic carbon showed generally better definition using the 870nm wavelength absorption weighting. Black carbon generation results from varying combustion rates from a number of sources including industrial processes and biomass burning. Cases with primarily black carbon showed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/919902','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/919902"><span><span class="hlt">Aerosol</span> mobility size spectrometer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Wang, Jian; Kulkarni, Pramod</p> <p>2007-11-20</p> <p>A device for measuring <span class="hlt">aerosol</span> size distribution within a sample containing <span class="hlt">aerosol</span> particles. The device generally includes a spectrometer housing defining an interior chamber and a camera for recording <span class="hlt">aerosol</span> size streams exiting the chamber. The housing includes an inlet for introducing a flow medium into the chamber in a flow direction, an <span class="hlt">aerosol</span> injection port adjacent the inlet for introducing a charged <span class="hlt">aerosol</span> sample into the chamber, a separation section for applying an electric field to the <span class="hlt">aerosol</span> sample across the flow direction and an outlet opposite the inlet. In the separation section, the <span class="hlt">aerosol</span> sample becomes entrained in the flow medium and the <span class="hlt">aerosol</span> particles within the <span class="hlt">aerosol</span> sample are separated by size into a plurality of <span class="hlt">aerosol</span> flow streams under the influence of the electric field. The camera is disposed adjacent the housing outlet for optically detecting a relative position of at least one <span class="hlt">aerosol</span> flow stream exiting the outlet and for optically detecting the number of <span class="hlt">aerosol</span> particles within the at least one <span class="hlt">aerosol</span> flow stream.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003TrGeo...4...91B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003TrGeo...4...91B"><span>Tropospheric <span class="hlt">Aerosols</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buseck, P. R.; Schwartz, S. E.</p> <p>2003-12-01</p> <p>It is widely believed that "On a clear day you can see forever," as proclaimed in the 1965 Broadway musical of the same name. While an admittedly beautiful thought, we all know that this concept is only figurative. Aside from Earth's curvature and Rayleigh scattering by air molecules, <span class="hlt">aerosols</span> - colloidal suspensions of solid or liquid particles in a gas - limit our vision. Even on the clearest day, there are billions of <span class="hlt">aerosol</span> particles per cubic meter of air.Atmospheric <span class="hlt">aerosols</span> are commonly referred to as smoke, dust, haze, and smog, terms that are loosely reflective of their origin and composition. <span class="hlt">Aerosol</span> particles have arisen naturally for eons from sea spray, volcanic emissions, wind entrainment of mineral dust, wildfires, and gas-to-particle conversion of hydrocarbons from plants and dimethylsulfide from the oceans. However, over the industrial period, the natural background <span class="hlt">aerosol</span> has been greatly augmented by anthropogenic contributions, i.e., those produced by human activities. One manifestation of this impact is reduced visibility (Figure 1). Thus, perhaps more than in other realms of geochemistry, when considering the composition of the troposphere one must consider the effects of these activities. The atmosphere has become a reservoir for vast quantities of anthropogenic emissions that exert important perturbations on it and on the planetary ecosystem in general. Consequently, much recent research focuses on the effects of human activities on the atmosphere and, through them, on the environment and Earth's climate. For these reasons consideration of the geochemistry of the atmosphere, and of atmospheric <span class="hlt">aerosols</span> in particular, must include the effects of human activities. (201K)Figure 1. Impairment of visibility by <span class="hlt">aerosols</span>. Photographs at Yosemite National Park, California, USA. (a) Low <span class="hlt">aerosol</span> concentration (particulate matter of aerodynamic diameter less than 2.5 μm, PM2.5=0.3 μg m-3; particulate matter of aerodynamic diameter less than 10 </p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol30/pdf/CFR-2010-title40-vol30-sec721-981.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol30/pdf/CFR-2010-title40-vol30-sec721-981.pdf"><span>40 CFR 721.981 - <span class="hlt">Substituted</span> naphtholoazo-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.981 <span class="hlt">Substituted</span> naphtholoazo-<span class="hlt">substituted</span> naphthalenyl-<span class="hlt">substituted</span> azonaphthol chromium complex. (a) Chemical substance and significant new...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ACPD...1114991M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ACPD...1114991M"><span>Black carbon <span class="hlt">aerosol</span> mixing state, organic <span class="hlt">aerosols</span> and <span class="hlt">aerosol</span> optical properties over the UK</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McMeeking, G. R.; Morgan, W. T.; Flynn, M.; Highwood, E. J.; Turnbull, K.; Haywood, J.; Coe, H.</p> <p>2011-05-01</p> <p>Black carbon (BC) <span class="hlt">aerosols</span> absorb sunlight thereby leading to a positive radiative forcing and a warming of climate and can also impact human health through their impact on the respiratory system. The state of mixing of BC with other <span class="hlt">aerosol</span> species, particularly the degree of internal/external mixing, has been highlighted as a major uncertainty in assessing its radiative forcing and hence its climate impact, but few in situ observations of mixing state exist. We present airborne single particle soot photometer (SP2) measurements of refractory BC (rBC) mass concentrations and mixing state coupled with <span class="hlt">aerosol</span> composition and optical properties measured in urban plumes and regional pollution over the UK. All data were obtained using instrumentation flown on the UK's BAe-146-301 large Atmospheric Research Aircraft (ARA) operated by the Facility for Airborne Atmospheric Measurements (FAAM). We measured sub-micron <span class="hlt">aerosol</span> composition using an <span class="hlt">aerosol</span> mass spectrometer (AMS) and used positive matrix factorization to separate hydrocarbon-like (HOA) and oxygenated organic <span class="hlt">aerosols</span> (OOA). We found a higher number fraction of thickly coated rBC particles in air masses with large OOA relative to HOA, higher ozone-to-nitrogen oxides (NOx) ratios and large concentrations of total sub-micron <span class="hlt">aerosol</span> mass relative to rBC mass concentrations. The more ozone- and OOA-rich air masses were associated with transport from continental Europe, while plumes from UK cities had higher HOA and NOx and fewer thickly coated rBC particles. We did not observe any significant change in the rBC mass absorption efficiency calculated from rBC mass and light absorption coefficients measured by a particle soot absorption photometer despite observing significant changes in <span class="hlt">aerosol</span> composition and rBC mixing state. The contributions of light scattering and absorption to total extinction (quantified by the single scattering albedo; SSA) did change for different air masses, with lower SSA observed in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.5441M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.5441M"><span>Atmosphere <span class="hlt">aerosol</span> satellite project <span class="hlt">Aerosol</span>-UA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Milinevsky, Gennadi; Yatskiv, Yaroslav; Syniavskyi, Ivan; Bovchaliuk, Andrii; Degtyaryov, Oleksandr; Sosonkin, Mikhail; Mishchenko, Michael; Danylevsky, Vassyl; Ivanov, Yury; Oberemok, Yevgeny; Masley, Volodymyr; Rosenbush, Vera; Moskalev, Sergii</p> <p>2017-04-01</p> <p>The experiment <span class="hlt">Aerosol</span>-UA is Ukrainian space mission aimed to the terrestrial atmospheric <span class="hlt">aerosol</span> spatial distribution and microphysics investigations. The experiment concept is based on idea of Glory/APS mission of precise orbital measurements of polarization and intensity of the sunlight scattered by the atmosphere, <span class="hlt">aerosol</span> and the surface the multichannel Scanning Polarimeter (ScanPol) with narrow field-of-view. ScanPol measurements will be accompanied by the wide-angle MultiSpectral Imager-Polarimeter (MSIP). The ScanPol is designed to measure Stokes parameters I, Q, U within the spectral range from the UV to the SWIR in a wide range of phase angles along satellite ground path. Expected ScanPol polarimetric accuracy is 0.15%. A high accuracy measurement of the degree of linear polarization is provided by on-board calibration of the ScanPol polarimeter. On-board calibration is performed for each scan of the mirror scanning system. A set of calibrators is viewed during the part of the scan range when the ScanPol polarimeter looks in the direction opposite to the Earth's surface. These reference assemblies provide calibration of the zero of the polarimetric scale (unpolarized reference assembly) and the scale factor for the polarimetric scale (polarized reference assembly). The zero of the radiometric scale is provided by the dark reference assembly.The spectral channels of the ScanPol are used to estimate the tropospheric <span class="hlt">aerosol</span> absorption, the <span class="hlt">aerosol</span> over the ocean and the land surface, the signals from cirrus clouds, stratospheric <span class="hlt">aerosols</span> caused by major volcanic eruptions, and the contribution of the Earth's surface. The imager-polarimeter MSIP will collect 60°x60° field-of-view images on the state of the atmosphere and surface in the area, where the ScanPol polarimeter will measure, to retrieve <span class="hlt">aerosol</span> optical depth and polarization properties of <span class="hlt">aerosol</span> by registration of three Stokes parameters simultaneously in three spectral channels. The two more</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20060047785','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060047785"><span><span class="hlt">Aerosol</span> Lidar and MODIS Satellite Comparisons for Future <span class="hlt">Aerosol</span> Loading Forecast</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>DeYoung, Russell; Szykman, James; Severance, Kurt; Chu, D. Allen; Rosen, Rebecca; Al-Saadi, Jassim</p> <p>2006-01-01</p> <p>Knowledge of the concentration and distribution of atmospheric <span class="hlt">aerosols</span> using both airborne lidar and satellite instruments is a field of active research. An aircraft based <span class="hlt">aerosol</span> lidar has been used to study the distribution of atmospheric <span class="hlt">aerosols</span> in the California Central Valley and eastern US coast. Concurrently, satellite <span class="hlt">aerosol</span> retrievals, from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Terra and Aqua satellites, were take over the Central Valley. The MODIS Level 2 <span class="hlt">aerosol</span> data product provides retrieved ambient <span class="hlt">aerosol</span> optical properties (e.g., optical depth (AOD) and size distribution) globally over ocean and land at a spatial resolution of 10 km. The Central Valley topography was overlaid with MODIS AOD (5x5 sq km resolution) and the <span class="hlt">aerosol</span> scattering vertical profiles from a lidar flight. Backward air parcel trajectories for the lidar data show that air from the Pacific and northern part of the Central Valley converge confining the <span class="hlt">aerosols</span> to the lower valley region and below the mixed layer. Below an altitude of 1 km, the lidar <span class="hlt">aerosol</span> and MODIS AOD exhibit good agreement. Both data sets indicate a high presence of <span class="hlt">aerosols</span> near Bakersfield and the Tehachapi Mountains. These and other results to be presented indicate that the majority of the <span class="hlt">aerosols</span> are below the mixed layer such that the MODIS AOD should correspond well with surface measurements. Lidar measurements will help interpret satellite AOD retrievals so that one day they can be used on a routine basis for prediction of boundary layer <span class="hlt">aerosol</span> pollution events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A24D..05K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A24D..05K"><span>The MAC <span class="hlt">aerosol</span> climatology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kinne, S.</p> <p>2015-12-01</p> <p><span class="hlt">Aerosol</span> is highly diverse in space and time. And many different <span class="hlt">aerosol</span> optical properties are needed (consistent to each other) for the determination of radiative effects. To sidestep a complex (and uncertain) <span class="hlt">aerosol</span> treatment (emission to mass to optics) a monthly gridded climatology for <span class="hlt">aerosol</span> properties has been developed. This MPI <span class="hlt">Aerosol</span> Climatology (MAC) is strongly tied to observational statistics for <span class="hlt">aerosol</span> column optical properties by AERONET (over land) and by MAN (over oceans). To fill spatial gaps, to address decadal change and to address vertical variability, these sparsely distributed local data are extended with central data of an ensemble of output from global models with complex <span class="hlt">aerosol</span> modules. This data merging in performed for <span class="hlt">aerosol</span> column amount (AOD), for <span class="hlt">aerosol</span> size (AOD,fine) and for <span class="hlt">aerosol</span> absorption (AAOD). The resulting MAC <span class="hlt">aerosol</span> climatology is an example for the combination of high quality local observations with spatial, temporal and vertical context from model simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010089249&hterms=causes+absorption+window&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DWhat%2Bcauses%2Babsorption%2Bwindow','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010089249&hterms=causes+absorption+window&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DWhat%2Bcauses%2Babsorption%2Bwindow"><span>Remote Sensing of <span class="hlt">Aerosol</span> and Non-<span class="hlt">Aerosol</span> Absorption</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kaufman, Y. J.; Dubovik, O.; Holben, B. N.; Remer, L. A.; Tanre, D.; Lau, William K. M. (Technical Monitor)</p> <p>2001-01-01</p> <p>Remote sensing of <span class="hlt">aerosol</span> from the new satellite instruments (e.g. MODIS from Terra) and ground based radiometers (e.g. the AERONET) provides the opportunity to measure the absorption characteristics of the ambient undisturbed <span class="hlt">aerosol</span> in the entire atmospheric column. For example Landsat and AERONET data are used to measure spectral absorption of sunlight by dust from West Africa. Both Application of the Landsat and AERONET data demonstrate that Saharan dust absorption of solar radiation is several times smaller than the current international standards. This is due to difficulties of measuring dust absorption in situ, and due to the often contamination of dust properties by the presence of air pollution or smoke. We use the remotely sensed <span class="hlt">aerosol</span> absorption properties described by the spectral sin le scattering albedo, together with statistics of the monthly optical thickness for the fine and coarse <span class="hlt">aerosol</span> derived from the MODIS data. The result is an estimate of the flux of solar radiation absorbed by the <span class="hlt">aerosol</span> layer in different regions around the globe where <span class="hlt">aerosol</span> is prevalent. If this <span class="hlt">aerosol</span> forcing through absorption is not included in global circulation models, it may be interpreted as anomalous absorption in these regions. In a preliminary exercise we also use the absorption measurements by AERONET, to derive the non-<span class="hlt">aerosol</span> absorption of the atmosphere in cloud free conditions. The results are obtained for the atmospheric windows: 0.44 microns, 0.66 microns, 0.86 microns and 1.05 microns. In all the locations over the land and ocean that were tested no anomalous absorption in these wavelengths, was found within absorption optical thickness of +/- 0.005.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24467190','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24467190"><span>Efficacy of face shields against cough <span class="hlt">aerosol</span> droplets from a cough simulator.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lindsley, William G; Noti, John D; Blachere, Francoise M; Szalajda, Jonathan V; Beezhold, Donald H</p> <p>2014-01-01</p> <p>Health care workers are exposed to potentially infectious airborne particles while providing routine care to coughing patients. However, much is not understood about the behavior of these <span class="hlt">aerosols</span> and the risks they pose. We used a coughing patient simulator and a breathing worker simulator to investigate the exposure of health care workers to cough <span class="hlt">aerosol</span> droplets, and to examine the efficacy of face shields in reducing this exposure. Our results showed that 0.9% of the initial burst of <span class="hlt">aerosol</span> from a cough can be inhaled by a worker 46 cm (18 inches) from the patient. During testing of an influenza-laden cough <span class="hlt">aerosol</span> with a volume median diameter (VMD) of 8.5 μm, wearing a face shield reduced the inhalational exposure of the worker by 96% in the period immediately after a cough. The face shield also reduced the surface contamination of a respirator by 97%. When a smaller cough <span class="hlt">aerosol</span> was used (VMD = 3.4 μm), the face shield was less effective, blocking only 68% of the cough and 76% of the surface contamination. In the period from 1 to 30 minutes after a cough, during which the <span class="hlt">aerosol</span> had dispersed throughout the room and larger particles had settled, the face shield reduced <span class="hlt">aerosol</span> inhalation by only 23%. Increasing the distance between the patient and worker to 183 cm (72 inches) reduced the exposure to influenza that occurred immediately after a cough by 92%. Our results show that health care workers can inhale infectious airborne particles while treating a coughing patient. Face shields can substantially reduce the short-term exposure of health care workers to large infectious <span class="hlt">aerosol</span> particles, but smaller particles can remain airborne longer and flow around the face shield more easily to be inhaled. Thus, face shields provide a useful adjunct to respiratory protection for workers caring for patients with respiratory infections. However, they cannot be used as a <span class="hlt">substitute</span> for respiratory protection when it is needed. [Supplementary materials are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/15003527-impact-aerosol-size-representation-modeling-aerosol-cloud-interactions','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/15003527-impact-aerosol-size-representation-modeling-aerosol-cloud-interactions"><span>Impact of <span class="hlt">aerosol</span> size representation on modeling <span class="hlt">aerosol</span>-cloud interactions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Zhang, Y.; Easter, R. C.; Ghan, S. J.; ...</p> <p>2002-11-07</p> <p>In this study, we use a 1-D version of a climate-<span class="hlt">aerosol</span>-chemistry model with both modal and sectional <span class="hlt">aerosol</span> size representations to evaluate the impact of <span class="hlt">aerosol</span> size representation on modeling <span class="hlt">aerosol</span>-cloud interactions in shallow stratiform clouds observed during the 2nd <span class="hlt">Aerosol</span> Characterization Experiment. Both the modal (with prognostic <span class="hlt">aerosol</span> number and mass or prognostic <span class="hlt">aerosol</span> number, surface area and mass, referred to as the Modal-NM and Modal-NSM) and the sectional approaches (with 12 and 36 sections) predict total number and mass for interstitial and activated particles that are generally within several percent of references from a high resolution 108-section approach.more » The modal approach with prognostic <span class="hlt">aerosol</span> mass but diagnostic number (referred to as the Modal-M) cannot accurately predict the total particle number and surface areas, with deviations from the references ranging from 7-161%. The particle size distributions are sensitive to size representations, with normalized absolute differences of up to 12% and 37% for the 36- and 12-section approaches, and 30%, 39%, and 179% for the Modal-NSM, Modal-NM, and Modal-M, respectively. For the Modal-NSM and Modal-NM, differences from the references are primarily due to the inherent assumptions and limitations of the modal approach. In particular, they cannot resolve the abrupt size transition between the interstitial and activated <span class="hlt">aerosol</span> fractions. For the 12- and 36-section approaches, differences are largely due to limitations of the parameterized activation for non-log-normal size distributions, plus the coarse resolution for the 12-section case. Differences are larger both with higher <span class="hlt">aerosol</span> (i.e., less complete activation) and higher SO2 concentrations (i.e., greater modification of the initial <span class="hlt">aerosol</span> distribution).« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21428387','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21428387"><span>Climate impact of biofuels in shipping: global model studies of the <span class="hlt">aerosol</span> indirect effect.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Righi, Mattia; Klinger, Carolin; Eyring, Veronika; Hendricks, Johannes; Lauer, Axel; Petzold, Andreas</p> <p>2011-04-15</p> <p><span class="hlt">Aerosol</span> emissions from international shipping are recognized to have a large impact on the Earth's radiation budget, directly by scattering and absorbing solar radiation and indirectly by altering cloud properties. New regulations have recently been approved by the International Maritime Organization (IMO) aiming at progressive reductions of the maximum sulfur content allowed in marine fuels from current 4.5% by mass down to 0.5% in 2020, with more restrictive limits already applied in some coastal regions. In this context, we use a global bottom-up algorithm to calculate geographically resolved emission inventories of gaseous (NO(x), CO, SO(2)) and <span class="hlt">aerosol</span> (black carbon, organic matter, sulfate) species for different kinds of low-sulfur fuels in shipping. We apply these inventories to study the resulting changes in radiative forcing, attributed to particles from shipping, with the global <span class="hlt">aerosol</span>-climate model EMAC-MADE. The emission factors for the different fuels are based on measurements at a test bed of a large diesel engine. We consider both fossil fuel (marine gas oil) and biofuels (palm and soy bean oil) as a <span class="hlt">substitute</span> for heavy fuel oil in the current (2006) fleet and compare their climate impact to that resulting from heavy fuel oil use. Our simulations suggest that ship-induced surface level concentrations of sulfate <span class="hlt">aerosol</span> are strongly reduced, up to about 40-60% in the high-traffic regions. This clearly has positive consequences for pollution reduction in the vicinity of major harbors. Additionally, such reductions in the <span class="hlt">aerosol</span> loading lead to a decrease of a factor of 3-4 in the indirect global <span class="hlt">aerosol</span> effect induced by emissions from international shipping.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ACP....11.9037M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ACP....11.9037M"><span>Black carbon <span class="hlt">aerosol</span> mixing state, organic <span class="hlt">aerosols</span> and <span class="hlt">aerosol</span> optical properties over the United Kingdom</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McMeeking, G. R.; Morgan, W. T.; Flynn, M.; Highwood, E. J.; Turnbull, K.; Haywood, J.; Coe, H.</p> <p>2011-09-01</p> <p>Black carbon (BC) <span class="hlt">aerosols</span> absorb sunlight thereby leading to a positive radiative forcing and a warming of climate and can also impact human health through their impact on the respiratory system. The state of mixing of BC with other <span class="hlt">aerosol</span> species, particularly the degree of internal/external mixing, has been highlighted as a major uncertainty in assessing its radiative forcing and hence its climate impact, but few in situ observations of mixing state exist. We present airborne single particle soot photometer (SP2) measurements of refractory BC (rBC) mass concentrations and mixing state coupled with <span class="hlt">aerosol</span> composition and optical properties measured in urban plumes and regional pollution over the United Kingdom. All data were obtained using instrumentation flown on the UK's BAe-146-301 large Atmospheric Research Aircraft (ARA) operated by the Facility for Airborne Atmospheric Measurements (FAAM). We measured sub-micron <span class="hlt">aerosol</span> composition using an <span class="hlt">aerosol</span> mass spectrometer (AMS) and used positive matrix factorization to separate hydrocarbon-like (HOA) and oxygenated organic <span class="hlt">aerosols</span> (OOA). We found a higher number fraction of thickly coated rBC particles in air masses with large OOA relative to HOA, higher ozone-to-nitrogen oxides (NOx) ratios and large concentrations of total sub-micron <span class="hlt">aerosol</span> mass relative to rBC mass concentrations. The more ozone- and OOA-rich air masses were associated with transport from continental Europe, while plumes from UK cities had higher HOA and NOx and fewer thickly coated rBC particles. We did not observe any significant change in the rBC mass absorption efficiency calculated from rBC mass and light absorption coefficients measured by a particle soot absorption photometer despite observing significant changes in <span class="hlt">aerosol</span> composition and rBC mixing state. The contributions of light scattering and absorption to total extinction (quantified by the single scattering albedo; SSA) did change for different air masses, with lower SSA</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ACP....13.4997D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ACP....13.4997D"><span>Characterization of urban <span class="hlt">aerosol</span> in Cork city (Ireland) using <span class="hlt">aerosol</span> mass spectrometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dall'Osto, M.; Ovadnevaite, J.; Ceburnis, D.; Martin, D.; Healy, R. M.; O'Connor, I. P.; Kourtchev, I.; Sodeau, J. R.; Wenger, J. C.; O'Dowd, C.</p> <p>2013-05-01</p> <p>Ambient wintertime background urban <span class="hlt">aerosol</span> in Cork city, Ireland, was characterized using <span class="hlt">aerosol</span> mass spectrometry. During the three-week measurement study in 2009, 93% of the ca. 1 350 000 single particles characterized by an <span class="hlt">Aerosol</span> Time-of-Flight Mass Spectrometer (TSI ATOFMS) were classified into five organic-rich particle types, internally mixed to different proportions with elemental carbon (EC), sulphate and nitrate, while the remaining 7% was predominantly inorganic in nature. Non-refractory PM1 <span class="hlt">aerosol</span> was characterized using a High Resolution Time-of-Flight <span class="hlt">Aerosol</span> Mass Spectrometer (Aerodyne HR-ToF-AMS) and was also found to comprise organic <span class="hlt">aerosol</span> as the most abundant species (62%), followed by nitrate (15%), sulphate (9%) and ammonium (9%), and chloride (5%). Positive matrix factorization (PMF) was applied to the HR-ToF-AMS organic matrix, and a five-factor solution was found to describe the variance in the data well. Specifically, "hydrocarbon-like" organic <span class="hlt">aerosol</span> (HOA) comprised 20% of the mass, "low-volatility" oxygenated organic <span class="hlt">aerosol</span> (LV-OOA) comprised 18%, "biomass burning" organic <span class="hlt">aerosol</span> (BBOA) comprised 23%, non-wood solid-fuel combustion "peat and coal" organic <span class="hlt">aerosol</span> (PCOA) comprised 21%, and finally a species type characterized by primary {m/z} peaks at 41 and 55, similar to previously reported "cooking" organic <span class="hlt">aerosol</span> (COA), but possessing different diurnal variations to what would be expected for cooking activities, contributed 18%. Correlations between the different particle types obtained by the two <span class="hlt">aerosol</span> mass spectrometers are also discussed. Despite wood, coal and peat being minor fuel types used for domestic space heating in urban areas, their relatively low combustion efficiencies result in a significant contribution to PM1 <span class="hlt">aerosol</span> mass (44% and 28% of the total organic <span class="hlt">aerosol</span> mass and non-refractory total PM1, respectively).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120017003','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120017003"><span>Estimating Marine <span class="hlt">Aerosol</span> Particle Volume and Number from Maritime <span class="hlt">Aerosol</span> Network Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sayer, A. M.; Smirnov, A.; Hsu, N. C.; Munchak, L. A.; Holben, B. N.</p> <p>2012-01-01</p> <p>As well as spectral <span class="hlt">aerosol</span> optical depth (AOD), <span class="hlt">aerosol</span> composition and concentration (number, volume, or mass) are of interest for a variety of applications. However, remote sensing of these quantities is more difficult than for AOD, as it is more sensitive to assumptions relating to <span class="hlt">aerosol</span> composition. This study uses spectral AOD measured on Maritime <span class="hlt">Aerosol</span> Network (MAN) cruises, with the additional constraint of a microphysical model for unpolluted maritime <span class="hlt">aerosol</span> based on analysis of <span class="hlt">Aerosol</span> Robotic Network (AERONET) inversions, to estimate these quantities over open ocean. When the MAN data are subset to those likely to be comprised of maritime <span class="hlt">aerosol</span>, number and volume concentrations obtained are physically reasonable. Attempts to estimate surface concentration from columnar abundance, however, are shown to be limited by uncertainties in vertical distribution. Columnar AOD at 550 nm and <span class="hlt">aerosol</span> number for unpolluted maritime cases are also compared with Moderate Resolution Imaging Spectroradiometer (MODIS) data, for both the present Collection 5.1 and forthcoming Collection 6. MODIS provides a best-fitting retrieval solution, as well as the average for several different solutions, with different <span class="hlt">aerosol</span> microphysical models. The average solution MODIS dataset agrees more closely with MAN than the best solution dataset. Terra tends to retrieve lower <span class="hlt">aerosol</span> number than MAN, and Aqua higher, linked with differences in the <span class="hlt">aerosol</span> models commonly chosen. Collection 6 AOD is likely to agree more closely with MAN over open ocean than Collection 5.1. In situations where spectral AOD is measured accurately, and <span class="hlt">aerosol</span> microphysical properties are reasonably well-constrained, estimates of <span class="hlt">aerosol</span> number and volume using MAN or similar data would provide for a greater variety of potential comparisons with <span class="hlt">aerosol</span> properties derived from satellite or chemistry transport model data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eosweb.larc.nasa.gov/project/misr/gallery/aerosols_europe','SCIGOV-ASDC'); return false;" href="https://eosweb.larc.nasa.gov/project/misr/gallery/aerosols_europe"><span><span class="hlt">Aerosols</span></span></a></p> <p><a target="_blank" href="http://eosweb.larc.nasa.gov/">Atmospheric Science Data Center </a></p> <p></p> <p>2013-04-17</p> <p>... depth. A color scale is used to represent this quantity, and high <span class="hlt">aerosol</span> amount is indicated by yellow or green pixels, and clearer skies ... out most clearly, whereas MISR's oblique cameras enhance sensitivity to even thin layers of <span class="hlt">aerosols</span>. In the March image, the only ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMGC43H1153T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMGC43H1153T"><span>Impact of Idealized Stratospheric <span class="hlt">Aerosol</span> Injection on the Future Ocean and Land Carbon Cycles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tjiputra, J.; Lauvset, S.</p> <p>2017-12-01</p> <p>Using a state-of-the-art Earth system model, we simulate stratospheric <span class="hlt">aerosol</span> injection (SAI) on top of the Representative Concentration Pathways 8.5 future scenario. Our idealized method prescribes <span class="hlt">aerosol</span> concentration, linearly increasing from 2020 to 2100, and thereafter remaining constant until 2200. In one of the scenarios, the model able to project future warming below 2 degree toward 2100, despite greatier warming persists in the high latitudes. When SAI is terminated in 2100, a rapid global warming of 0.35 K yr-1 (as compared to 0.05 K yr-1 under RCP8.5) is simulated in the subsequent 10 years, and the global mean temperature rapidly returns to levels close to the reference state. In contrast to earlier findings, we show a weak response in the terrestrial carbon sink during SAI implementation in the 21st century, which we attribute to nitrogen limitation. The SAI increases the land carbon uptake in the temperate forest-, grassland-, and shrub-dominated regions. The resultant lower temperatures lead to a reduction in the heterotrophic respiration rate and increase soil carbon retention. Changes in precipitation patterns are key drivers for variability in vegetation carbon. Upon SAI termination, the level of vegetation carbon storage returns to the reference case, whereas the soil carbon remains high. The ocean absorbs nearly 10% more carbon in the <span class="hlt">geoengineered</span> simulation than in the reference simulation, leading to a ˜15 ppm lower atmospheric CO2 concentration in 2100. The largest enhancement in uptake occurs in the North Atlantic. In both hemispheres' polar regions, SAI delays the sea ice melting and, consequently, export production remains low. Despite inducing little impact on surface acidification, in the deep water of North Atlantic, SAI-induced circulation changes accelerate the ocean acidification rate and broaden the affected area. Since the deep ocean provides vital ecosystem function and services, e.g., fish stocks, this accelerated changes</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.A11A0851J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.A11A0851J"><span>Modeling the SOA Forming Potential of <span class="hlt">Substituted</span> Dihydrofurans from Alkane + OH Reactions in the Atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jordan, C. E.; Griffin, R. J.; Lim, Y. B.; Ziemann, P. J.; Atkinson, R.; Arey, J.</p> <p>2005-12-01</p> <p>Recent laboratory studies show that δ-hydroxycarbonyls formed in the atmosphere via OH-initiated reactions with alkanes can cyclize then dehydrate to form <span class="hlt">substituted</span> dihydrofurans. These dihydrofurans are highly reactive, with lifetimes in the atmosphere of 1.3 h (OH), 24 s (NO3), and 7 min (O3). The ability of the δ-hydroxycarbonyls to cyclize and dehydrate has been shown to increase with increasing carbon number. Recent laboratory results show that the secondary organic <span class="hlt">aerosol</span> (SOA) yields from alkanes also increase with carbon number reaching ~53% for C15. The reaction mechanism proposed based on the chamber results is the basis of the modeling study presented here. We have incorporated this proposed mechanism into the Caltech Atmospheric Chemistry Mechanism (CACM). For computational reasons, similar compounds are lumped together and represented by a single suitable compound. In the present case, alkanes are lumped into 3 groups: short chains (≤C6), medium chains (C7 - C12), and long chains (≥C13). SOA yields obtained in chamber studies increase dramatically from 0.5% for C8 to 25% for C12. The most dramatic increase is observed from C11 (8%) to C13 (~50%). This is attributed to the low volatility of first generation products contributing to the SOA from longer chain alkanes. Here we have studied OH reactions with the <span class="hlt">substituted</span> dihydrofurans for medium (represented by C10) and long (represented by C16) chain alkanes using CACM along with the <span class="hlt">aerosol</span> partitioning module MPMPO (Model to Predict the Multi-phase Partitioning of Organics). We will present the results of this modeling study, characterizing the influence of <span class="hlt">substituted</span> dihydrofurans on the SOA forming potential of alkanes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ACP....18.2329D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ACP....18.2329D"><span>Evaluating the mutagenic potential of <span class="hlt">aerosol</span> organic compounds using informatics-based screening</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Decesari, Stefano; Kovarich, Simona; Pavan, Manuela; Bassan, Arianna; Ciacci, Andrea; Topping, David</p> <p>2018-02-01</p> <p>Whilst general policy objectives to reduce airborne particulate matter (PM) health effects are to reduce exposure to PM as a whole, emerging evidence suggests that more detailed metrics associating impacts with different <span class="hlt">aerosol</span> components might be needed. Since it is impossible to conduct toxicological screening on all possible molecular species expected to occur in <span class="hlt">aerosol</span>, in this study we perform a proof-of-concept evaluation on the information retrieved from in silico toxicological predictions, in which a subset (N = 104) of secondary organic <span class="hlt">aerosol</span> (SOA) compounds were screened for their mutagenicity potential. An extensive database search showed that experimental data are available for 13 % of the compounds, while reliable predictions were obtained for 82 %. A multivariate statistical analysis of the compounds based on their physico-chemical, structural, and mechanistic properties showed that 80 % of the compounds predicted as mutagenic were grouped into six clusters, three of which (five-membered lactones from monoterpene oxidation, oxygenated multifunctional compounds from <span class="hlt">substituted</span> benzene oxidation, and hydroperoxides from several precursors) represent new candidate groups of compounds for future toxicological screenings. These results demonstrate that coupling model-generated compositions to in silico toxicological screening might enable more comprehensive exploration of the mutagenic potential of specific SOA components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A51E2119L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A51E2119L"><span>Sources and Variability of <span class="hlt">Aerosols</span> and <span class="hlt">Aerosol</span>-Cloud Interactions in the Arctic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, H.; Zhang, B.; Taylor, P. C.; Moore, R.; Barahona, D.; Fairlie, T. D.; Chen, G.; Ham, S. H.; Kato, S.</p> <p>2017-12-01</p> <p>Arctic sea ice in recent decades has significantly declined. This requires understanding of the Arctic surface energy balance, of which clouds are a major driver. However, the mechanisms for the formation and evolution of clouds in the Arctic and the roles of <span class="hlt">aerosols</span> therein are highly uncertain. Here we conduct data analysis and global model simulations to examine the sources and variability of <span class="hlt">aerosols</span> and <span class="hlt">aerosol</span>-cloud interactions in the Arctic. We use the MERRA-2 reanalysis data (2006-present) from the NASA Global Modeling and Assimilation Office (GMAO) to (1) quantify contributions of different <span class="hlt">aerosol</span> types to the <span class="hlt">aerosol</span> budget and <span class="hlt">aerosol</span> optical depths in the Arctic, (2) ­examine <span class="hlt">aerosol</span> distributions and variability and diagnose the major pathways for mid-latitude pollution transport to the Arctic, including their seasonal and interannual variability, and (3) characterize the distribution and variability of clouds (cloud optical depth, cloud fraction, cloud liquid and ice water path, cloud top height) in the Arctic. We compare MERRA-2 <span class="hlt">aerosol</span> and cloud properties with those from C3M, a 3-D <span class="hlt">aerosol</span> and cloud data product developed at NASA Langley Research Center and merged from multiple A-Train satellite (CERES, CloudSat, CALIPSO, and MODIS) observations. We also conduct perturbation experiments using the NASA GEOS-5 chemistry-climate model (with GOCART <span class="hlt">aerosol</span> module coupled with two-moment cloud microphysics), and discuss the roles of various types of <span class="hlt">aerosols</span> in the formation and evolution of clouds in the Arctic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/943811','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/943811"><span>Impact of <span class="hlt">Geoengineering</span> Schemes on the Global Hydrological Cycle</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Bala, G; Duffy, P; Taylor, K</p> <p>2007-12-07</p> <p>The rapidly rising CO{sub 2} level in the atmosphere has led to proposals of climate stabilization via '<span class="hlt">Geoengineering</span>' schemes that would mitigate climate change by intentionally reducing the solar radiation incident on earth's surface. In this paper, we address the impact of these climate stabilization schemes on the global hydrological cycle, using equilibrium simulations from an atmospheric general circulation model coupled to a slab ocean model. We show that insolation reductions sufficient to offset global-scale temperature increases lead to a decrease in the intensity of the global hydrologic cycle. This occurs because solar forcing is more effective in driving changesmore » in global mean evaporation than is CO{sub 2} forcing of a similar magnitude. In the model used here, the hydrologic sensitivity, defined as the percentage change in global mean precipitation per degree warming, is 2.4% for solar forcing, but only 1.5% for CO{sub 2} forcing. Although other models and the climate system itself may differ quantitatively from this result, the conclusion can be understood based on simple considerations of the surface energy budget and thus is likely to be robust. Compared to changing temperature by altering greenhouse gas concentrations, changing temperature by varying insolation results in larger changes in net radiative fluxes at the surface; these are compensated by larger changes in latent and sensible heat fluxes. Hence the hydrological cycle is more sensitive to temperature adjustment via changes in insolation than changes in greenhouse gases. This implies that an alteration in solar forcing might offset temperature changes or hydrological changes from greenhouse warming, but could not cancel both at once.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A52D..07L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A52D..07L"><span><span class="hlt">Aerosol</span> Indirect Effects on Cirrus Clouds in Global <span class="hlt">Aerosol</span>-Climate Models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, X.; Zhang, K.; Wang, Y.; Neubauer, D.; Lohmann, U.; Ferrachat, S.; Zhou, C.; Penner, J.; Barahona, D.; Shi, X.</p> <p>2015-12-01</p> <p>Cirrus clouds play an important role in regulating the Earth's radiative budget and water vapor distribution in the upper troposphere. <span class="hlt">Aerosols</span> can act as solution droplets or ice nuclei that promote ice nucleation in cirrus clouds. Anthropogenic emissions from fossil fuel and biomass burning activities have substantially perturbed and enhanced concentrations of <span class="hlt">aerosol</span> particles in the atmosphere. Global <span class="hlt">aerosol</span>-climate models (GCMs) have now been used to quantify the radiative forcing and effects of <span class="hlt">aerosols</span> on cirrus clouds (IPCC AR5). However, the estimate uncertainty is very large due to the different representation of ice cloud formation and evolution processes in GCMs. In addition, large discrepancies have been found between model simulations in terms of the spatial distribution of ice-nucleating <span class="hlt">aerosols</span>, relative humidity, and temperature fluctuations, which contribute to different estimates of the <span class="hlt">aerosol</span> indirect effect through cirrus clouds. In this presentation, four GCMs with the start-of-the art representations of cloud microphysics and <span class="hlt">aerosol</span>-cloud interactions are used to estimate the <span class="hlt">aerosol</span> indirect effects on cirrus clouds and to identify the causes of the discrepancies. The estimated global and annual mean anthropogenic <span class="hlt">aerosol</span> indirect effect through cirrus clouds ranges from 0.1 W m-2 to 0.3 W m-2 in terms of the top-of-the-atmosphere (TOA) net radiation flux, and 0.5-0.6 W m-2 for the TOA longwave flux. Despite the good agreement on global mean, large discrepancies are found at the regional scale. The physics behind the <span class="hlt">aerosol</span> indirect effect is dramatically different. Our analysis suggests that burden of ice-nucleating <span class="hlt">aerosols</span> in the upper troposphere, ice nucleation frequency, and relative role of ice formation processes (i.e., homogeneous versus heterogeneous nucleation) play key roles in determining the characteristics of the simulated <span class="hlt">aerosol</span> indirect effects. In addition to the indirect effect estimate, we also use field campaign</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ACPD...1229657D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ACPD...1229657D"><span>Characterization of urban <span class="hlt">aerosol</span> in Cork City (Ireland) using <span class="hlt">aerosol</span> mass spectrometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dall'Osto, M.; Ovadnevaite, J.; Ceburnis, D.; Martin, D.; Healy, R. M.; O'Connor, I. P.; Sodeau, J. R.; Wenger, J. C.; O'Dowd, C.</p> <p>2012-11-01</p> <p>Ambient wintertime background urban <span class="hlt">aerosol</span> in Cork City, Ireland, was characterized using <span class="hlt">aerosol</span> mass spectrometry. During the three-week measurement study in 2009, 93% of the 1 200 000 single particles characterized by an <span class="hlt">Aerosol</span> Time-Of-Flight Mass Spectrometer (TSI ATOFMS) were classified into five organic-rich particle types, internally-mixed to different proportions with Elemental Carbon (EC), sulphate and nitrate while the remaining 7% was predominantly inorganic in nature. Non-refractory PM1 <span class="hlt">aerosol</span> was also characterized using a High Resolution Time-Of-Flight Aerodyne <span class="hlt">Aerosol</span> Mass Spectrometer (HR-ToF-AMS) and was also found to comprise organic matter as the most abundant species (62%), followed by nitrate (15%), sulphate (9%) and ammonium (9%), and then chloride (5%). Positive matrix factorization (PMF) was applied to the HR-ToF-AMS organic matrix and a five-factor solution was found to describe the variance in the data well. Specifically, "Hydrocarbon-like" Organic <span class="hlt">Aerosol</span> (HOA) comprised 19% of the mass, "Oxygenated low volatility" Organic <span class="hlt">Aerosols</span> (LV-OOA) comprised 19%, "Biomass wood Burning" Organic <span class="hlt">Aerosol</span> (BBOA) comprised 23%, non-wood solid-fuel combustion "Peat and Coal" Organic <span class="hlt">Aerosol</span> (PCOA) comprised 21%, and finally, a species type characterized by primary m/z peaks at 41 and 55, similar to previously-reported "Cooking" Organic <span class="hlt">Aerosol</span> (COA) but possessing different diurnal variations to what would be expected for cooking activities, contributed 18%. Despite wood, cool and peat being minor fuel types used for domestic space heating in urban areas, their relatively low combustion efficiencies result in a significant contribution to PM1 <span class="hlt">aerosol</span> mass (44% and 28% of the total organic <span class="hlt">aerosols</span> mass and non refractory PM1, respectively).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.4254P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.4254P"><span><span class="hlt">Aerosol</span> Climate Time Series in ESA <span class="hlt">Aerosol</span>_cci</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Popp, Thomas; de Leeuw, Gerrit; Pinnock, Simon</p> <p>2016-04-01</p> <p>Within the ESA Climate Change Initiative (CCI) <span class="hlt">Aerosol</span>_cci (2010 - 2017) conducts intensive work to improve algorithms for the retrieval of <span class="hlt">aerosol</span> information from European sensors. Meanwhile, full mission time series of 2 GCOS-required <span class="hlt">aerosol</span> parameters are completely validated and released: <span class="hlt">Aerosol</span> Optical Depth (AOD) from dual view ATSR-2 / AATSR radiometers (3 algorithms, 1995 - 2012), and stratospheric extinction profiles from star occultation GOMOS spectrometer (2002 - 2012). Additionally, a 35-year multi-sensor time series of the qualitative Absorbing <span class="hlt">Aerosol</span> Index (AAI) together with sensitivity information and an AAI model simulator is available. Complementary <span class="hlt">aerosol</span> properties requested by GCOS are in a "round robin" phase, where various algorithms are inter-compared: fine mode AOD, mineral dust AOD (from the thermal IASI spectrometer, but also from ATSR instruments and the POLDER sensor), absorption information and <span class="hlt">aerosol</span> layer height. As a quasi-reference for validation in few selected regions with sparse ground-based observations the multi-pixel GRASP algorithm for the POLDER instrument is used. Validation of first dataset versions (vs. AERONET, MAN) and inter-comparison to other satellite datasets (MODIS, MISR, SeaWIFS) proved the high quality of the available datasets comparable to other satellite retrievals and revealed needs for algorithm improvement (for example for higher AOD values) which were taken into account for a reprocessing. The datasets contain pixel level uncertainty estimates which were also validated and improved in the reprocessing. For the three ATSR algorithms the use of an ensemble method was tested. The paper will summarize and discuss the status of dataset reprocessing and validation. The focus will be on the ATSR, GOMOS and IASI datasets. Pixel level uncertainties validation will be summarized and discussed including unknown components and their potential usefulness and limitations. Opportunities for time series extension</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19879288','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19879288"><span>Characterization of Florida red tide <span class="hlt">aerosol</span> and the temporal profile of <span class="hlt">aerosol</span> concentration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheng, Yung Sung; Zhou, Yue; Pierce, Richard H; Henry, Mike; Baden, Daniel G</p> <p>2010-05-01</p> <p>Red tide <span class="hlt">aerosols</span> containing <span class="hlt">aerosolized</span> brevetoxins are produced during the red tide bloom and transported by wind to coastal areas of Florida. This study reports the characterization of Florida red tide <span class="hlt">aerosols</span> in human volunteer studies, in which an asthma cohort spent 1h on Siesta Beach (Sarasota, Florida) during <span class="hlt">aerosolized</span> red tide events and non-exposure periods. <span class="hlt">Aerosol</span> concentrations, brevetoxin levels, and particle size distribution were measured. Hourly filter samples were taken and analyzed for brevetoxin and NaCl concentrations. In addition, the <span class="hlt">aerosol</span> mass concentration was monitored in real time. The results indicated that during a non-exposure period in October 2004, no brevetoxin was detected in the water, resulting in non-detectable levels of brevetoxin in the <span class="hlt">aerosol</span>. In March 2005, the time-averaged concentrations of brevetoxins in water samples were moderate, in the range of 5-10 microg/L, and the corresponding brevetoxin level of Florida red tide <span class="hlt">aerosol</span> ranged between 21 and 39 ng/m(3). The temporal profiles of red tide <span class="hlt">aerosol</span> concentration in terms of mass, NaCl, and brevetoxin were in good agreement, indicating that NaCl and brevetoxins are components of the red tide <span class="hlt">aerosol</span>. By continuously monitoring the marine <span class="hlt">aerosol</span> and wind direction at Siesta Beach, we observed that the marine <span class="hlt">aerosol</span> concentration varied as the wind direction changed. The temporal profile of the Florida red tide <span class="hlt">aerosol</span> during a sampling period could be explained generally with the variation of wind direction. Copyright 2009 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JQSRT.125...93C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JQSRT.125...93C"><span>The optical properties of absorbing <span class="hlt">aerosols</span> with fractal soot aggregates: Implications for <span class="hlt">aerosol</span> remote sensing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cheng, Tianhai; Gu, Xingfa; Wu, Yu; Chen, Hao; Yu, Tao</p> <p>2013-08-01</p> <p>Applying sphere <span class="hlt">aerosol</span> models to replace the absorbing fine-sized dominated <span class="hlt">aerosols</span> can potentially result in significant errors in the climate models and <span class="hlt">aerosol</span> remote sensing retrieval. In this paper, the optical properties of absorbing fine-sized dominated <span class="hlt">aerosol</span> were modeled, which are taking into account the fresh emitted soot particles (agglomerates of primary spherules), aged soot particles (semi-externally mixed with other weakly absorbing <span class="hlt">aerosols</span>), and coarse <span class="hlt">aerosol</span> particles (dust particles). The optical properties of the individual fresh and aged soot aggregates are calculated using the superposition T-matrix method. In order to quantify the morphology effect of absorbing <span class="hlt">aerosol</span> models on the <span class="hlt">aerosol</span> remote sensing retrieval, the ensemble averaged optical properties of absorbing fine-sized dominated <span class="hlt">aerosols</span> are calculated based on the size distribution of fine <span class="hlt">aerosols</span> (fresh and aged soot) and coarse <span class="hlt">aerosols</span>. The corresponding optical properties of sphere absorbing <span class="hlt">aerosol</span> models using Lorenz-Mie solutions were presented for comparison. The comparison study demonstrates that the sphere absorbing <span class="hlt">aerosol</span> models underestimate the absorption ability of the fine-sized dominated <span class="hlt">aerosol</span> particles. The morphology effect of absorbing fine-sized dominated <span class="hlt">aerosols</span> on the TOA radiances and polarized radiances is also investigated. It is found that the sphere <span class="hlt">aerosol</span> models overestimate the TOA reflectance and polarized reflectance by approximately a factor of 3 at wavelength of 0.865 μm. In other words, the fine-sized dominated <span class="hlt">aerosol</span> models can cause large errors in the retrieved <span class="hlt">aerosol</span> properties if satellite reflectance measurements are analyzed using the conventional Mie theory for spherical particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150023480','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150023480"><span>MATRIX-VBS Condensing Organic <span class="hlt">Aerosols</span> in an <span class="hlt">Aerosol</span> Microphysics Model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gao, Chloe Y.; Tsigaridis, Konstas; Bauer, Susanne E.</p> <p>2015-01-01</p> <p>The condensation of organic <span class="hlt">aerosols</span> is represented in a newly developed box-model scheme, where its effect on the growth and composition of particles are examined. We implemented the volatility-basis set (VBS) framework into the <span class="hlt">aerosol</span> mixing state resolving microphysical scheme Multiconfiguration <span class="hlt">Aerosol</span> TRacker of mIXing state (MATRIX). This new scheme is unique and advances the representation of organic <span class="hlt">aerosols</span> in models in that, contrary to the traditional treatment of organic <span class="hlt">aerosols</span> as non-volatile in most climate models and in the original version of MATRIX, this new scheme treats them as semi-volatile. Such treatment is important because low-volatility organics contribute significantly to the growth of particles. The new scheme includes several classes of semi-volatile organic compounds from the VBS framework that can partition among <span class="hlt">aerosol</span> populations in MATRIX, thus representing the growth of particles via condensation of low volatility organic vapors. Results from test cases representing Mexico City and a Finish forrest condistions show good representation of the time evolutions of concentration for VBS species in the gas phase and in the condensed particulate phase. Emitted semi-volatile primary organic <span class="hlt">aerosols</span> evaporate almost completely in the high volatile range, and they condense more efficiently in the low volatility range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/7033854-relationship-between-fluid-bed-aerosol-generator-operation-aerosol-produced','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/7033854-relationship-between-fluid-bed-aerosol-generator-operation-aerosol-produced"><span>Relationship between fluid bed <span class="hlt">aerosol</span> generator operation and the <span class="hlt">aerosol</span> produced</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Carpenter, R.L.; Yerkes, K.</p> <p>1980-12-01</p> <p>The relationships between bed operation in a fluid bed <span class="hlt">aerosol</span> generator and <span class="hlt">aerosol</span> output were studied. A two-inch diameter fluid bed <span class="hlt">aerosol</span> generator (FBG) was constructed using stainless steel powder as a fluidizing medium. Fly ash from coal combustion was <span class="hlt">aerosolized</span> and the influence of FBG operating parameters on <span class="hlt">aerosol</span> mass median aerodynamic diameter (MMAD), geometric standard deviation (sigma/sub g/) and concentration was examined. In an effort to extend observations on large fluid beds to small beds using fine bed particles, minimum fluidizing velocities and elutriation constant were computed. Although FBG minimum fluidizing velocity agreed well with calculations, FBG elutriationmore » constant did not. The results of this study show that the properties of <span class="hlt">aerosols</span> produced by a FBG depend on fluid bed height and air flow through the bed after the minimum fluidizing velocity is exceeded.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120011689','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120011689"><span>Global Atmospheric <span class="hlt">Aerosol</span> Modeling</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hendricks, Johannes; Aquila, Valentina; Righi, Mattia</p> <p>2012-01-01</p> <p>Global <span class="hlt">aerosol</span> models are used to study the distribution and properties of atmospheric <span class="hlt">aerosol</span> particles as well as their effects on clouds, atmospheric chemistry, radiation, and climate. The present article provides an overview of the basic concepts of global atmospheric <span class="hlt">aerosol</span> modeling and shows some examples from a global <span class="hlt">aerosol</span> simulation. Particular emphasis is placed on the simulation of <span class="hlt">aerosol</span> particles and their effects within global climate models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A23L..03P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A23L..03P"><span><span class="hlt">Aerosol</span> Climate Time Series Evaluation In ESA <span class="hlt">Aerosol</span>_cci</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Popp, T.; de Leeuw, G.; Pinnock, S.</p> <p>2015-12-01</p> <p>Within the ESA Climate Change Initiative (CCI) <span class="hlt">Aerosol</span>_cci (2010 - 2017) conducts intensive work to improve algorithms for the retrieval of <span class="hlt">aerosol</span> information from European sensors. By the end of 2015 full mission time series of 2 GCOS-required <span class="hlt">aerosol</span> parameters are completely validated and released: <span class="hlt">Aerosol</span> Optical Depth (AOD) from dual view ATSR-2 / AATSR radiometers (3 algorithms, 1995 - 2012), and stratospheric extinction profiles from star occultation GOMOS spectrometer (2002 - 2012). Additionally, a 35-year multi-sensor time series of the qualitative Absorbing <span class="hlt">Aerosol</span> Index (AAI) together with sensitivity information and an AAI model simulator is available. Complementary <span class="hlt">aerosol</span> properties requested by GCOS are in a "round robin" phase, where various algorithms are inter-compared: fine mode AOD, mineral dust AOD (from the thermal IASI spectrometer), absorption information and <span class="hlt">aerosol</span> layer height. As a quasi-reference for validation in few selected regions with sparse ground-based observations the multi-pixel GRASP algorithm for the POLDER instrument is used. Validation of first dataset versions (vs. AERONET, MAN) and inter-comparison to other satellite datasets (MODIS, MISR, SeaWIFS) proved the high quality of the available datasets comparable to other satellite retrievals and revealed needs for algorithm improvement (for example for higher AOD values) which were taken into account for a reprocessing. The datasets contain pixel level uncertainty estimates which are also validated. The paper will summarize and discuss the results of major reprocessing and validation conducted in 2015. The focus will be on the ATSR, GOMOS and IASI datasets. Pixel level uncertainties validation will be summarized and discussed including unknown components and their potential usefulness and limitations. Opportunities for time series extension with successor instruments of the Sentinel family will be described and the complementarity of the different satellite <span class="hlt">aerosol</span> products</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A41K..01F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A41K..01F"><span>Evaluating <span class="hlt">Aerosol</span> Process Modules within the Framework of the <span class="hlt">Aerosol</span> Modeling Testbed</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fast, J. D.; Velu, V.; Gustafson, W. I.; Chapman, E.; Easter, R. C.; Shrivastava, M.; Singh, B.</p> <p>2012-12-01</p> <p>Factors that influence predictions of <span class="hlt">aerosol</span> direct and indirect forcing, such as <span class="hlt">aerosol</span> mass, composition, size distribution, hygroscopicity, and optical properties, still contain large uncertainties in both regional and global models. New <span class="hlt">aerosol</span> treatments are usually implemented into a 3-D atmospheric model and evaluated using a limited number of measurements from a specific case study. Under this modeling paradigm, the performance and computational efficiency of several treatments for a specific <span class="hlt">aerosol</span> process cannot be adequately quantified because many other processes among various modeling studies (e.g. grid configuration, meteorology, emission rates) are different as well. The scientific community needs to know the advantages and disadvantages of specific <span class="hlt">aerosol</span> treatments when the meteorology, chemistry, and other <span class="hlt">aerosol</span> processes are identical in order to reduce the uncertainties associated with <span class="hlt">aerosols</span> predictions. To address these issues, an <span class="hlt">Aerosol</span> Modeling Testbed (AMT) has been developed that systematically and objectively evaluates new <span class="hlt">aerosol</span> treatments for use in regional and global models. The AMT consists of the modular Weather Research and Forecasting (WRF) model, a series testbed cases for which extensive in situ and remote sensing measurements of meteorological, trace gas, and <span class="hlt">aerosol</span> properties are available, and a suite of tools to evaluate the performance of meteorological, chemical, <span class="hlt">aerosol</span> process modules. WRF contains various parameterizations of meteorological, chemical, and <span class="hlt">aerosol</span> processes and includes interactive <span class="hlt">aerosol</span>-cloud-radiation treatments similar to those employed by climate models. In addition, the physics suite from the Community Atmosphere Model version 5 (CAM5) have also been ported to WRF so that they can be tested at various spatial scales and compared directly with field campaign data and other parameterizations commonly used by the mesoscale modeling community. Data from several campaigns, including the 2006</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15..196L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15..196L"><span>Uncertainties of <span class="hlt">aerosol</span> retrieval from neglecting non-sphericity of dust <span class="hlt">aerosols</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Chi; Xue, Yong; Yang, Leiku; Guang, Jie</p> <p>2013-04-01</p> <p>The Mie theory is conventionally applied to calculate <span class="hlt">aerosol</span> optical properties in satellite remote sensing applications, while dust <span class="hlt">aerosols</span> cannot be well modeled by the Mie calculation for their non-sphericity. It has been cited in Mishchenko et al. (1995; 1997) that neglecting non-sphericity can severely influence <span class="hlt">aerosol</span> optical depth (AOD, ?) retrieval in case of dust <span class="hlt">aerosols</span> because of large difference of phase functions under spherical and non-spherical assumptions, whereas this uncertainty has not been thoroughly studied. This paper aims at a better understanding of uncertainties on AOD retrieval caused by <span class="hlt">aerosol</span> non-sphericity. A dust <span class="hlt">aerosol</span> model with known refractive index and size distribution is generated from long-term AERONET observations since 1999 over China. Then <span class="hlt">aerosol</span> optical properties, such as the extinction, phase function, single scattering albedo (SSA) are calculated respectively in the assumption of spherical and non-spherical <span class="hlt">aerosols</span>. Mie calculation is carried out for spherical assumption, meanwhile for non-spherical <span class="hlt">aerosol</span> modeling, we adopt the pre-calculated scattering kernels and software package presented by Dubovik et al. (2002; 2006), which describes dust as a shape mixture of randomly oriented polydisperse spheroids. Consequently we generate two lookup tables (LUTspheric and LUTspheroid) from simulated satellite received reflectance at top of atmosphere (TOA) under varieties of observing conditions and <span class="hlt">aerosol</span> loadings using Second Simulation of a Satellite Signal in the Solar Spectrum - Vector (6SV) code. All the simulations are made at 550 nm, and for simplicity the Lambertian surface is assumed. Using the obtained LUTs we examine the differences of TOA reflectance (Δ?TOA = ?spheric - ?spheroid) under different surface reflectance and <span class="hlt">aerosol</span> loadings. Afterwards AOD is retrieved using LUTspheric from the simulated TOA reflectance by LUTspheroid in order to detect the retrieval errors (Δ? = ?retreived -?input) induced</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRD..11619205S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRD..11619205S"><span>An <span class="hlt">aerosol</span> climatology for a rapidly growing arid region (southern Arizona): Major <span class="hlt">aerosol</span> species and remotely sensed <span class="hlt">aerosol</span> properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sorooshian, Armin; Wonaschütz, Anna; Jarjour, Elias G.; Hashimoto, Bryce I.; Schichtel, Bret A.; Betterton, Eric A.</p> <p>2011-10-01</p> <p>This study reports a comprehensive characterization of atmospheric <span class="hlt">aerosol</span> particle properties in relation to meteorological and back trajectory data in the southern Arizona region, which includes two of the fastest growing metropolitan areas in the United States (Phoenix and Tucson). Multiple data sets (MODIS, AERONET, OMI/TOMS, MISR, GOCART, ground-based <span class="hlt">aerosol</span> measurements) are used to examine monthly trends in <span class="hlt">aerosol</span> composition, <span class="hlt">aerosol</span> optical depth (AOD), and <span class="hlt">aerosol</span> size. Fine soil, sulfate, and organics dominate PM2.5 mass in the region. Dust strongly influences the region between March and July owing to the dry and hot meteorological conditions and back trajectory patterns. Because monsoon precipitation begins typically in July, dust levels decrease, while AOD, sulfate, and organic <span class="hlt">aerosol</span> reach their maximum levels because of summertime photochemistry and monsoon moisture. Evidence points to biogenic volatile organic compounds being a significant source of secondary organic <span class="hlt">aerosol</span> in this region. Biomass burning also is shown to be a major contributor to the carbonaceous <span class="hlt">aerosol</span> budget in the region, leading to enhanced organic and elemental carbon levels aloft at a sky-island site north of Tucson (Mt. Lemmon). Phoenix exhibits different monthly trends for <span class="hlt">aerosol</span> components in comparison with the other sites owing to the strong influence of fossil carbon and anthropogenic dust. Trend analyses between 1988 and 2009 indicate that the strongest statistically significant trends are reductions in sulfate, elemental carbon, and organic carbon, and increases in fine soil during the spring (March-May) at select sites. These results can be explained by population growth, land-use changes, and improved source controls.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AtmRe.182..243P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AtmRe.182..243P"><span><span class="hlt">Aerosols</span> and lightning activity: The effect of vertical profile and <span class="hlt">aerosol</span> type</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Proestakis, E.; Kazadzis, S.; Lagouvardos, K.; Kotroni, V.; Amiridis, V.; Marinou, E.; Price, C.; Kazantzidis, A.</p> <p>2016-12-01</p> <p>The Cloud-<span class="hlt">Aerosol</span> Lidar with Orthogonal Polarization (CALIOP) instrument on board the Cloud-<span class="hlt">Aerosol</span> Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite has been utilized for the first time in a study regarding lightning activity modulation due to <span class="hlt">aerosols</span>. Lightning activity observations, obtained by the ZEUS long range Lightning Detection Network, European Centre for Medium range Weather Forecasts (ECMWF) Convective Available Potential Energy (CAPE) data and Cloud Fraction (CF) retrieved by MODIS on board Aqua satellite have been combined with CALIPSO CALIOP data over the Mediterranean basin and for the period March to November, from 2007 to 2014. The results indicate that lightning activity is enhanced during days characterized by higher <span class="hlt">Aerosol</span> Optical Depth (AOD) values, compared to days with no lightning. This study contributes to existing studies on the link between lightning activity and <span class="hlt">aerosols</span>, which have been based just on columnar AOD satellite retrievals, by performing a deeper analysis into the effect of <span class="hlt">aerosol</span> profiles and <span class="hlt">aerosol</span> types. Correlation coefficients of R = 0.73 between the CALIPSO AOD and the number of lightning strikes detected by ZEUS and of R = 0.93 between ECMWF CAPE and lightning activity are obtained. The analysis of extinction coefficient values at 532 nm indicates that at an altitudinal range exists, between 1.1 km and 2.9 km, where the values for extinction coefficient of lightning-active and non-lightning-active cases are statistically significantly different. Finally, based on the CALIPSO <span class="hlt">aerosol</span> subtype classification, we have investigated the <span class="hlt">aerosol</span> conditions of lightning-active and non-lightning-active cases. According to the results polluted dust <span class="hlt">aerosols</span> are more frequently observed during non-lightning-active days, while dust and smoke <span class="hlt">aerosols</span> are more abundant in the atmosphere during the lightning-active days.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007ACPD....7.6357K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007ACPD....7.6357K"><span><span class="hlt">Aerosol</span> climatology: on the discrimination of <span class="hlt">aerosol</span> types over four AERONET sites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaskaoutis, D. G.; Kambezidis, H. D.; Hatzianastassiou, N.; Kosmopoulos, P. G.; Badarinath, K. V. S.</p> <p>2007-05-01</p> <p><span class="hlt">Aerosols</span> have a significant regional and global effect on climate, which is about equal in magnitude but opposite in sign to that of greenhouse gases. Nevertheless, the <span class="hlt">aerosol</span> climatic effect changes strongly with space and time because of the large variability of <span class="hlt">aerosol</span> physical and optical properties, which is due to the variety of their sources, which are natural, and anthropogenic, and their dependence on the prevailing meteorological and atmospheric conditions. Characterization of <span class="hlt">aerosol</span> properties is of major importance for the assessment of their role for climate. In the present study, 3-year <span class="hlt">AErosol</span> RObotic NETwork (AERONET) data from ground-based sunphotometer measurements are used to establish climatologies of <span class="hlt">aerosol</span> optical depth (AOD) and Ångström exponent α in several key locations of the world, characteristic of different atmospheric environments. Using daily mean values of AOD at 500 nm (AOD500) and Ångström exponent at the pair of wavelengths 440 and 870 nm (α 440-870), a discrimination of the different <span class="hlt">aerosol</span> types occurring in each location is achieved. For this discrimination, appropriate thresholds for AOD500 and α 440-870 are applied. The discrimination of <span class="hlt">aerosol</span> types in each location is made on an annual and seasonal basis. It is shown that a single <span class="hlt">aerosol</span> type in a given location can exist only under specific conditions (e.g. intense forest fires or dust outbreaks), while the presence of well-mixed <span class="hlt">aerosols</span> is the accustomed situation. Background clean <span class="hlt">aerosol</span> conditions (AOD500<0.06) are mostly found over remote oceanic surfaces occurring on average in ~56.7% of total cases, while this situation is quite rare over land (occurrence of 3.8-13.7%). Our analysis indicates that these percentages change significantly from season to season. The spectral dependence of AOD exhibits large differences between the examined locations, while it exhibits a strong annual cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AMT.....6.1919H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AMT.....6.1919H"><span><span class="hlt">Aerosol</span> retrieval experiments in the ESA <span class="hlt">Aerosol</span>_cci project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holzer-Popp, T.; de Leeuw, G.; Griesfeller, J.; Martynenko, D.; Klüser, L.; Bevan, S.; Davies, W.; Ducos, F.; Deuzé, J. L.; Graigner, R. G.; Heckel, A.; von Hoyningen-Hüne, W.; Kolmonen, P.; Litvinov, P.; North, P.; Poulsen, C. A.; Ramon, D.; Siddans, R.; Sogacheva, L.; Tanre, D.; Thomas, G. E.; Vountas, M.; Descloitres, J.; Griesfeller, J.; Kinne, S.; Schulz, M.; Pinnock, S.</p> <p>2013-08-01</p> <p>Within the ESA Climate Change Initiative (CCI) project <span class="hlt">Aerosol</span>_cci (2010-2013), algorithms for the production of long-term total column <span class="hlt">aerosol</span> optical depth (AOD) datasets from European Earth Observation sensors are developed. Starting with eight existing pre-cursor algorithms three analysis steps are conducted to improve and qualify the algorithms: (1) a series of experiments applied to one month of global data to understand several major sensitivities to assumptions needed due to the ill-posed nature of the underlying inversion problem, (2) a round robin exercise of "best" versions of each of these algorithms (defined using the step 1 outcome) applied to four months of global data to identify mature algorithms, and (3) a comprehensive validation exercise applied to one complete year of global data produced by the algorithms selected as mature based on the round robin exercise. The algorithms tested included four using AATSR, three using MERIS and one using PARASOL. This paper summarizes the first step. Three experiments were conducted to assess the potential impact of major assumptions in the various <span class="hlt">aerosol</span> retrieval algorithms. In the first experiment a common set of four <span class="hlt">aerosol</span> components was used to provide all algorithms with the same assumptions. The second experiment introduced an <span class="hlt">aerosol</span> property climatology, derived from a combination of model and sun photometer observations, as a priori information in the retrievals on the occurrence of the common <span class="hlt">aerosol</span> components. The third experiment assessed the impact of using a common nadir cloud mask for AATSR and MERIS algorithms in order to characterize the sensitivity to remaining cloud contamination in the retrievals against the baseline dataset versions. The impact of the algorithm changes was assessed for one month (September 2008) of data: qualitatively by inspection of monthly mean AOD maps and quantitatively by comparing daily gridded satellite data against daily averaged AERONET sun photometer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1239469-two-column-aerosol-project-phase-overview-impact-elevated-aerosol-layers-aerosol-optical-depth','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1239469-two-column-aerosol-project-phase-overview-impact-elevated-aerosol-layers-aerosol-optical-depth"><span>The Two-Column <span class="hlt">Aerosol</span> Project: Phase I - Overview and Impact of Elevated <span class="hlt">Aerosol</span> Layers on <span class="hlt">Aerosol</span> Optical Depth</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Berg, Larry K.; Fast, Jerome D.; Barnard, James C.</p> <p>2016-01-08</p> <p>The Two-Column <span class="hlt">Aerosol</span> Project (TCAP), which was conducted from June 2012 through June 2013, was a unique field study that was designed to provide a comprehensive data set that can be used to investigate a number of important climate science questions, including those related to <span class="hlt">aerosol</span> mixing state and <span class="hlt">aerosol</span> radiative forcing. The study was designed to sample the atmosphere at a number of altitudes, from near the surface to as high as 8 km, within two atmospheric columns; one located near the coast of North America (over Cape Cod, MA) and a second over the Atlantic Ocean several hundredmore » kilometers from the coast. TCAP included the yearlong deployment of the U.S. Department of Energy’s (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) that was located at the base of the Cape Cod column, as well as summer and winter aircraft intensive observation periods of the ARM Aerial Facility. One important finding from TCAP is the relatively common occurrence (on four of six nearly cloud-free flights) of elevated <span class="hlt">aerosol</span> layers in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA high-spectral resolution lidar (HSRL-2). These layers contributed up to 60% of the total <span class="hlt">aerosol</span> optical depth (AOD) observed in the column. Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the <span class="hlt">aerosol</span> in the layers was found to have increased amounts of biomass burning <span class="hlt">aerosol</span> and nitrate compared to the <span class="hlt">aerosol</span> found near the surface.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1336066-two-column-aerosol-project-phase-overview-impact-elevated-aerosol-layers-aerosol-optical-depth','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1336066-two-column-aerosol-project-phase-overview-impact-elevated-aerosol-layers-aerosol-optical-depth"><span>The Two-Column <span class="hlt">Aerosol</span> Project: Phase I-Overview and impact of elevated <span class="hlt">aerosol</span> layers on <span class="hlt">aerosol</span> optical depth</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Berg, Larry K.; Fast, Jerome D.; Barnard, James C.; ...</p> <p>2016-01-08</p> <p>The Two-Column <span class="hlt">Aerosol</span> Project (TCAP), conducted from June 2012 through June 2013, was a unique study designed to provide a comprehensive data set that can be used to investigate a number of important climate science questions, including those related to <span class="hlt">aerosol</span> mixing state and <span class="hlt">aerosol</span> radiative forcing. The study was designed to sample the atmosphere between and within two atmospheric columns; one fixed near the coast of North America (over Cape Cod, MA) and a second moveable column over the Atlantic Ocean several hundred kilometers from the coast. The U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facilitymore » (AMF) was deployed at the base of the Cape Cod column, and the ARM Aerial Facility was utilized for the summer and winter intensive observation periods. One important finding from TCAP is that four of six nearly cloud-free flight days had <span class="hlt">aerosol</span> layers aloft in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA high-spectral resolution lidar (HSRL-2). In addition, these layers contributed up to 60% of the total observed <span class="hlt">aerosol</span> optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the <span class="hlt">aerosol</span> in the layers was found to have increased amounts of biomass burning material and nitrate compared to <span class="hlt">aerosol</span> found near the surface. Lastly, while there was a great deal of spatial and day-to-day variability in the <span class="hlt">aerosol</span> chemical composition and optical properties, no systematic differences between the two columns were observed.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20180000133&hterms=layer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dlayer','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20180000133&hterms=layer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dlayer"><span>The Two-Column <span class="hlt">Aerosol</span> Project: Phase I - Overview and Impact of Elevated <span class="hlt">Aerosol</span> Layers on <span class="hlt">Aerosol</span> Optical Depth</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Berg, Larry K.; Fast, Jerome D.; Barnard, James C.; Burton, Sharon P.; Cairns, Brian; Chand, Duli; Comstock, Jennifer M.; Dunagan, Stephen; Ferrare, Richard A.; Flynn, Connor J.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20180000133'); toggleEditAbsImage('author_20180000133_show'); toggleEditAbsImage('author_20180000133_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20180000133_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20180000133_hide"></p> <p>2015-01-01</p> <p>The Two-Column <span class="hlt">Aerosol</span> Project (TCAP), conducted from June 2012 through June 2013, was a unique study designed to provide a comprehensive data set that can be used to investigate a number of important climate science questions, including those related to <span class="hlt">aerosol</span> mixing state and <span class="hlt">aerosol</span> radiative forcing. The study was designed to sample the atmosphere be tween and within two atmospheric columns; one fixed near the coast of North America (over Cape Cod, MA) and a second moveable column over the Atlantic Ocean several hundred kilometers from the coast. The U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) was deployed at the base of the Cape Cod column, and the ARM Aerial Facility was utilized for the summer and winter intensive observation periods. One important finding from TCAP is that four of six nearly cloud-free flight days had <span class="hlt">aerosol</span> layers aloft in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA high-spectral resolution lidar (HSRL-2).These layer s contributed up to 60 of the total observed <span class="hlt">aerosol</span> optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the <span class="hlt">aerosol</span> in the layers was found to have increased amounts of biomass burning material and nitrate compared to <span class="hlt">aerosol</span> found near the surface. In addition, while there was a great deal of spatial and day-to-day variability in the <span class="hlt">aerosol</span> chemical composition and optical properties, no systematic differences between the two columns were observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRD..121..336B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRD..121..336B"><span>The Two-Column <span class="hlt">Aerosol</span> Project: Phase I—Overview and impact of elevated <span class="hlt">aerosol</span> layers on <span class="hlt">aerosol</span> optical depth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berg, Larry K.; Fast, Jerome D.; Barnard, James C.; Burton, Sharon P.; Cairns, Brian; Chand, Duli; Comstock, Jennifer M.; Dunagan, Stephen; Ferrare, Richard A.; Flynn, Connor J.; Hair, Johnathan W.; Hostetler, Chris A.; Hubbe, John; Jefferson, Anne; Johnson, Roy; Kassianov, Evgueni I.; Kluzek, Celine D.; Kollias, Pavlos; Lamer, Katia; Lantz, Kathleen; Mei, Fan; Miller, Mark A.; Michalsky, Joseph; Ortega, Ivan; Pekour, Mikhail; Rogers, Ray R.; Russell, Philip B.; Redemann, Jens; Sedlacek, Arthur J.; Segal-Rosenheimer, Michal; Schmid, Beat; Shilling, John E.; Shinozuka, Yohei; Springston, Stephen R.; Tomlinson, Jason M.; Tyrrell, Megan; Wilson, Jacqueline M.; Volkamer, Rainer; Zelenyuk, Alla; Berkowitz, Carl M.</p> <p>2016-01-01</p> <p>The Two-Column <span class="hlt">Aerosol</span> Project (TCAP), conducted from June 2012 through June 2013, was a unique study designed to provide a comprehensive data set that can be used to investigate a number of important climate science questions, including those related to <span class="hlt">aerosol</span> mixing state and <span class="hlt">aerosol</span> radiative forcing. The study was designed to sample the atmosphere between and within two atmospheric columns; one fixed near the coast of North America (over Cape Cod, MA) and a second moveable column over the Atlantic Ocean several hundred kilometers from the coast. The U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) was deployed at the base of the Cape Cod column, and the ARM Aerial Facility was utilized for the summer and winter intensive observation periods. One important finding from TCAP is that four of six nearly cloud-free flight days had <span class="hlt">aerosol</span> layers aloft in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA high-spectral resolution lidar (HSRL-2). These layers contributed up to 60% of the total observed <span class="hlt">aerosol</span> optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the <span class="hlt">aerosol</span> in the layers was found to have increased amounts of biomass burning material and nitrate compared to <span class="hlt">aerosol</span> found near the surface. In addition, while there was a great deal of spatial and day-to-day variability in the <span class="hlt">aerosol</span> chemical composition and optical properties, no systematic differences between the two columns were observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17119596','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17119596"><span><span class="hlt">Aerosol</span> polarization effects on atmospheric correction and <span class="hlt">aerosol</span> retrievals in ocean color remote sensing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Menghua</p> <p>2006-12-10</p> <p>The current ocean color data processing system for the Sea-viewing Wide Field-of-View Sensor (SeaWiFS) and the moderate resolution imaging spectroradiometer (MODIS) uses the Rayleigh lookup tables that were generated using the vector radiative transfer theory with inclusion of the polarization effects. The polarization effects, however, are not accounted for in the <span class="hlt">aerosol</span> lookup tables for the ocean color data processing. I describe a study of the <span class="hlt">aerosol</span> polarization effects on the atmospheric correction and <span class="hlt">aerosol</span> retrieval algorithms in the ocean color remote sensing. Using an efficient method for the multiple vector radiative transfer computations, <span class="hlt">aerosol</span> lookup tables that include polarization effects are generated. Simulations have been carried out to evaluate the <span class="hlt">aerosol</span> polarization effects on the derived ocean color and <span class="hlt">aerosol</span> products for all possible solar-sensor geometries and the various <span class="hlt">aerosol</span> optical properties. Furthermore, the new <span class="hlt">aerosol</span> lookup tables have been implemented in the SeaWiFS data processing system and extensively tested and evaluated with SeaWiFS regional and global measurements. Results show that in open oceans (maritime environment), the <span class="hlt">aerosol</span> polarization effects on the ocean color and <span class="hlt">aerosol</span> products are usually negligible, while there are some noticeable effects on the derived products in the coastal regions with nonmaritime <span class="hlt">aerosols</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://familydoctor.org/sugar-substitutes/?adfree=true','NIH-MEDLINEPLUS'); return false;" href="https://familydoctor.org/sugar-substitutes/?adfree=true"><span>Sugar <span class="hlt">Substitutes</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... <span class="hlt">Substitutes</span> Share Print Sugar <span class="hlt">substitutes</span> are chemical or plant-based substances used to sweeten or enhance the ... made with saccharin. Stevia sweeteners Stevia is a plant-based sugar <span class="hlt">substitute</span> that has no calories. The ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.1535B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.1535B"><span>The effect of organic <span class="hlt">aerosol</span> material on <span class="hlt">aerosol</span> reactivity towards ozone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Batenburg, Anneke; Gaston, Cassandra; Thornton, Joel; Virtanen, Annele</p> <p>2015-04-01</p> <p>After <span class="hlt">aerosol</span> particles are formed or emitted into the atmosphere, heterogeneous reactions with gaseous oxidants cause them to 'age'. Aging can change <span class="hlt">aerosol</span> properties, such as the hygroscopicity, which is an important parameter in how the particles scatter radiation and form clouds. Conversely, heterogeneous reactions on <span class="hlt">aerosol</span> particles play a significant role in the cycles of various atmospheric trace gases. Organic compounds, a large part of the total global <span class="hlt">aerosol</span> matter, can exist in liquid or amorphous (semi)solid physical phases. Different groups have shown that reactions with ozone (O3) can be limited by bulk diffusion in organic <span class="hlt">aerosol</span>, particularly in viscous, (semi)solid materials, and that organic coatings alter the surface interactions between gas and <span class="hlt">aerosol</span> particles. We aim to better understand and quantify how the viscosity and phase of organic <span class="hlt">aerosol</span> matter affect gas-particle interactions. We have chosen the reaction of O3 with particles composed of a potassium iodide (KI) core and a variable organic coating as a model system. The reaction is studied in an <span class="hlt">aerosol</span> flow reactor that consists of a laminar flow tube and a movable, axial injector for the injection of O3. The <span class="hlt">aerosol</span>-containing air is inserted at the tube's top. The interaction length (and therefore time), between the particles and the O3 can be varied by moving the injector. Alternatively, the production of <span class="hlt">aerosol</span> particles can be modulated. The remaining O3 concentration is monitored from the bottom of the tube and particle concentrations are measured simultaneously, which allows us to calculate the reactive uptake coefficient γ. We performed exploratory experiments with internally mixed KI and polyethylene glycol (PEG) particles at the University of Washington (UW) in a setup with a residence time around 50 s. <span class="hlt">Aerosol</span> particles were generated in an atomizer from solutions with varying concentrations of KI and PEG and inserted into the flow tube after they were diluted and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRD..11612205S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRD..11612205S"><span>Direct and semidirect <span class="hlt">aerosol</span> effects of southern African biomass burning <span class="hlt">aerosol</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sakaeda, Naoko; Wood, Robert; Rasch, Philip J.</p> <p>2011-06-01</p> <p>Direct and semidirect radiative effects of biomass burning <span class="hlt">aerosols</span> from southern African fires during July-October are investigated using 20 year runs of the Community Atmospheric Model (CAM) coupled to a slab ocean model. <span class="hlt">Aerosol</span> optical depth is constrained using observations in clear skies from Moderate Resolution Imaging Spectroradiometer (MODIS) and for <span class="hlt">aerosol</span> layers above clouds from Cloud <span class="hlt">Aerosol</span> Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). Over the ocean, where the <span class="hlt">aerosol</span> layers are primarily located above cloud, negative top of atmosphere (TOA) semidirect radiative effects associated with increased low cloud cover dominate over a weaker positive all-sky direct radiative effect (DRE). In contrast, over the land where the <span class="hlt">aerosols</span> are often below or within cloud layers, reductions in cloud liquid water path (LWP) lead to a positive semidirect radiative effect that dominates over a near-zero DRE. Over the ocean, the cloud response can be understood as a response to increased lower tropospheric stability (LTS) which is caused both by radiative heating in overlying layers and surface cooling in response to direct <span class="hlt">aerosol</span> forcing. The marine cloud changes are robust to changes in the cloud parameterization (removal of the hard-wired dependence of clouds on LTS), suggesting that they are physically realistic. Over land, decreased LWP is consistent with weaker convection driven by increased static stability. Over the entire region the overall TOA radiative effect from the biomass burning <span class="hlt">aerosols</span> is almost zero due to opposing effects over the land and ocean. However, the surface forcing is strongly negative, which leads to a reduction in precipitation and also a reduction in sensible heat flux. The former is primarily realized through reductions in convective precipitation on both the southern and northern flanks of the convective precipitation region spanning the equatorial rain forest and the Intertropical Convergence Zone (ITCZ) in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/868192','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/868192"><span>Solid <span class="hlt">aerosol</span> generator</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Prescott, Donald S.; Schober, Robert K.; Beller, John</p> <p>1992-01-01</p> <p>An improved solid <span class="hlt">aerosol</span> generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid <span class="hlt">aerosol</span> generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated <span class="hlt">aerosol</span> in a grounded, conical heating chamber, achieving high recovery and flow rates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5271142','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/5271142"><span><span class="hlt">Aerosol</span> distribution apparatus</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Hanson, W.D.</p> <p></p> <p>An apparatus for uniformly distributing an <span class="hlt">aerosol</span> to a plurality of filters mounted in a plenum, wherein the <span class="hlt">aerosol</span> and air are forced through a manifold system by means of a jet pump and released into the plenum through orifices in the manifold. The apparatus allows for the simultaneous <span class="hlt">aerosol</span>-testing of all the filters in the plenum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.4472K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.4472K"><span>simplified <span class="hlt">aerosol</span> representations in global modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kinne, Stefan; Peters, Karsten; Stevens, Bjorn; Rast, Sebastian; Schutgens, Nick; Stier, Philip</p> <p>2015-04-01</p> <p>The detailed treatment of <span class="hlt">aerosol</span> in global modeling is complex and time-consuming. Thus simplified approaches are investigated, which prescribe 4D (space and time) distributions of <span class="hlt">aerosol</span> optical properties and of <span class="hlt">aerosol</span> microphysical properties. <span class="hlt">Aerosol</span> optical properties are required to assess <span class="hlt">aerosol</span> direct radiative effects and <span class="hlt">aerosol</span> microphysical properties (in terms of their ability as <span class="hlt">aerosol</span> nuclei to modify cloud droplet concentrations) are needed to address the indirect <span class="hlt">aerosol</span> impact on cloud properties. Following the simplifying concept of the monthly gridded (1x1 lat/lon) <span class="hlt">aerosol</span> climatology (MAC), new approaches are presented and evaluated against more detailed methods, including comparisons to detailed simulations with complex <span class="hlt">aerosol</span> component modules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070016619','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070016619"><span>Global <span class="hlt">Aerosol</span> Optical Models and Lookup Tables for the New MODIS <span class="hlt">Aerosol</span> Retrieval over Land</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Levy, Robert C.; Remer, Loraine A.; Dubovik, Oleg</p> <p>2007-01-01</p> <p>Since 2000, MODIS has been deriving <span class="hlt">aerosol</span> properties over land from MODIS observed spectral reflectance, by matching the observed reflectance with that simulated for selected <span class="hlt">aerosol</span> optical models, <span class="hlt">aerosol</span> loadings, wavelengths and geometrical conditions (that are contained in a lookup table or 'LUT'). Validation exercises have showed that MODIS tends to under-predict <span class="hlt">aerosol</span> optical depth (tau) in cases of large tau (tau greater than 1.0), signaling errors in the assumed <span class="hlt">aerosol</span> optical properties. Using the climatology of almucantur retrievals from the hundreds of global AERONET sunphotometer sites, we found that three spherical-derived models (describing fine-sized dominated <span class="hlt">aerosol</span>), and one spheroid-derived model (describing coarse-sized dominated <span class="hlt">aerosol</span>, presumably dust) generally described the range of observed global <span class="hlt">aerosol</span> properties. The fine dominated models were separated mainly by their single scattering albedo (omega(sub 0)), ranging from non-absorbing <span class="hlt">aerosol</span> (omega(sub 0) approx. 0.95) in developed urban/industrial regions, to neutrally absorbing <span class="hlt">aerosol</span> (omega(sub 0) approx.90) in forest fire burning and developing industrial regions, to absorbing <span class="hlt">aerosol</span> (omega(sub 0) approx. 0.85) in regions of savanna/grassland burning. We determined the dominant model type in each region and season, to create a 1 deg. x 1 deg. grid of assumed <span class="hlt">aerosol</span> type. We used vector radiative transfer code to create a new LUT, simulating the four <span class="hlt">aerosol</span> models, in four MODIS channels. Independent AERONET observations of spectral tau agree with the new models, indicating that the new models are suitable for use by the MODIS <span class="hlt">aerosol</span> retrieval.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ACP....16.4191N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ACP....16.4191N"><span>Stratospheric ozone changes under solar <span class="hlt">geoengineering</span>: implications for UV exposure and air quality</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nowack, Peer Johannes; Abraham, Nathan Luke; Braesicke, Peter; Pyle, John Adrian</p> <p>2016-03-01</p> <p>Various forms of <span class="hlt">geoengineering</span> have been proposed to counter anthropogenic climate change. Methods which aim to modify the Earth's energy balance by reducing insolation are often subsumed under the term solar radiation management (SRM). Here, we present results of a standard SRM modelling experiment in which the incoming solar irradiance is reduced to offset the global mean warming induced by a quadrupling of atmospheric carbon dioxide. For the first time in an atmosphere-ocean coupled climate model, we include atmospheric composition feedbacks for this experiment. While the SRM scheme considered here could offset greenhouse gas induced global mean surface warming, it leads to important changes in atmospheric composition. We find large stratospheric ozone increases that induce significant reductions in surface UV-B irradiance, which would have implications for vitamin D production. In addition, the higher stratospheric ozone levels lead to decreased ozone photolysis in the troposphere. In combination with lower atmospheric specific humidity under SRM, this results in overall surface ozone concentration increases in the idealized G1 experiment. Both UV-B and surface ozone changes are important for human health. We therefore highlight that both stratospheric and tropospheric ozone changes must be considered in the assessment of any SRM scheme, due to their important roles in regulating UV exposure and air quality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17034300','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17034300"><span>Generating monodisperse pharmacological <span class="hlt">aerosols</span> using the spinning-top <span class="hlt">aerosol</span> generator.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Biddiscombe, Martyn F; Barnes, Peter J; Usmani, Omar S</p> <p>2006-01-01</p> <p>Pharmacological <span class="hlt">aerosols</span> of precisely controlled particle size and narrow dispersity can be generated using the spinning-top <span class="hlt">aerosol</span> generator (STAG). The ability of the STAG to generate monodisperse <span class="hlt">aerosols</span> from solutions of raw drug compounds makes it a valuable research instrument. In this paper, the versatility of this instrument has been further demonstrated by <span class="hlt">aerosolizing</span> a range of commercially available nebulized pulmonary therapy preparations. Nebules of Flixotide (fluticasone propionate), Pulmicort (budesonide), Combivent (salbutamol sulphate and ipratropium bromide), Bricanyl (terbutaline sulphate), Atrovent(ipratropium bromide), and Salamol (salbutamol sulphate) were each mixed with ethanol and delivered to the STAG. Monodisperse drug <span class="hlt">aerosol</span> distributions were generated with MMADs of 0.95-6.7 microm. To achieve larger particle sizes from the nebulizer drug suspensions, the STAG formed compound particle agglomerates derived from the smaller insoluble drug particles. These compound agglomerates behaved aerodynamically as a single particle, and this was verified using an aerodynamic particle sizer and an Andersen Cascade Impactor. Scanning electron microscope images demonstrated their physical structure. On the other hand using the nebulizer drug solutions, spherical particles proportional to the original droplet diameter were generated. The <span class="hlt">aerosols</span> generated by the STAG can allow investigators to study the scientific principles of inhaled drug deposition and lung physiology for a range of therapeutic agents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A33H0339G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A33H0339G"><span>A Monte-Carlo Analysis of Organic <span class="hlt">Aerosol</span> Volatility with <span class="hlt">Aerosol</span> Microphysics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gao, C. Y.; Tsigaridis, K.; Bauer, S. E.</p> <p>2016-12-01</p> <p>A newly developed box model scheme, MATRIX-VBS, includes the volatility-basis set (VBS) framework in an <span class="hlt">aerosol</span> microphysical scheme MATRIX (Multiconfiguration <span class="hlt">Aerosol</span> TRacker of mIXing state), which resolves <span class="hlt">aerosol</span> mass and number concentrations and <span class="hlt">aerosol</span> mixing state. The new scheme advanced the representation of organic <span class="hlt">aerosols</span> in Earth system models by improving the traditional and simplistic treatment of organic <span class="hlt">aerosols</span> as non-volatile and with a fixed size distribution. Further development includes adding the condensation of organics on coarse mode <span class="hlt">aerosols</span> - dust and sea salt, thus making all organics in the system semi-volatile. To test and simplify the model, a Monte-Carlo analysis is performed to pin point which processes affect organics the most under which chemical and meteorological conditions. Since the model's parameterizations have the ability to capture a very wide range of conditions, from very clean to very polluted and for a wide range of meteorological conditions, all possible scenarios on Earth across the whole parameter space, including temperature, location, emissions and oxidant levels, are examined. The Monte-Carlo simulations provide quantitative information on the sensitivity of the newly developed model and help us understand how organics are affecting the size distribution, mixing state and volatility distribution at varying levels of meteorological conditions and pollution levels. In addition, these simulations give information on which parameters play a critical role in the <span class="hlt">aerosol</span> distribution and evolution in the atmosphere and which do not, that will facilitate the simplification of the box model, an important step in its implementation in the global model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/7273153','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/7273153"><span>Solid <span class="hlt">aerosol</span> generator</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Prescott, D.S.; Schober, R.K.; Beller, J.</p> <p>1992-03-17</p> <p>An improved solid <span class="hlt">aerosol</span> generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration is disclosed. The improved solid <span class="hlt">aerosol</span> generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated <span class="hlt">aerosol</span> in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988RvGeo..26...89S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988RvGeo..26...89S"><span>Antarctic <span class="hlt">aerosols</span> - A review</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shaw, Glenn E.</p> <p>1988-02-01</p> <p>Tropospheric <span class="hlt">aerosols</span> with the diameter range of half a micron reside in the atmosphere for tens of days and teleconnect Antarctica with other regions by transport that reaches planetary scales of distances; thus, the <span class="hlt">aerosol</span> on the Antarctic ice represents 'memory modules' of events that took place at regions separated from Antarctica by tens of thousands of kilometers. In terms of <span class="hlt">aerosol</span> mass, the <span class="hlt">aerosol</span> species include insoluble crustal products (less than 5 percent), transported sea-salt residues (highly variable but averaging about 10 percent), Ni-rich meteoric material, and anomalously enriched material with an unknown origin. Most (70-90 percent by mass) of the <span class="hlt">aerosol</span> over the Antarctic ice shield, however, is the 'natural acid sulfate <span class="hlt">aerosol</span>', apparently deriving from biological processes taking place in the surrounding oceans.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AtmEn..54..511C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AtmEn..54..511C"><span>Characterization of urban <span class="hlt">aerosol</span> using <span class="hlt">aerosol</span> mass spectrometry and proton nuclear magnetic resonance spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cleveland, M. J.; Ziemba, L. D.; Griffin, R. J.; Dibb, J. E.; Anderson, C. H.; Lefer, B.; Rappenglück, B.</p> <p>2012-07-01</p> <p>Particulate matter was measured during August and September of 2006 in Houston as part of the Texas Air Quality Study II Radical and <span class="hlt">Aerosol</span> Measurement Project. <span class="hlt">Aerosol</span> size and composition were determined using an Aerodyne quadrupole <span class="hlt">aerosol</span> mass spectrometer. <span class="hlt">Aerosol</span> was dominated by sulfate (4.1 ± 2.6 μg m-3) and organic material (5.5 ± 4.0 μg m-3), with contributions of organic material from both primary (˜32%) and secondary (˜68%) sources. Secondary organic <span class="hlt">aerosol</span> appears to be formed locally. In addition, 29 <span class="hlt">aerosol</span> filter samples were analyzed using proton nuclear magnetic resonance (1H NMR) spectroscopy to determine relative concentrations of organic functional groups. Houston <span class="hlt">aerosols</span> are less oxidized than those observed elsewhere, with smaller relative contributions of carbon-oxygen double bonds. These particles do not fit 1H NMR source apportionment fingerprints for identification of secondary, marine, and biomass burning organic <span class="hlt">aerosol</span>, suggesting that a new fingerprint for highly urbanized and industrially influenced locations be established.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JChPh.147v0901B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JChPh.147v0901B"><span>Perspective: <span class="hlt">Aerosol</span> microphysics: From molecules to the chemical physics of <span class="hlt">aerosols</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bzdek, Bryan R.; Reid, Jonathan P.</p> <p>2017-12-01</p> <p><span class="hlt">Aerosols</span> are found in a wide diversity of contexts and applications, including the atmosphere, pharmaceutics, and industry. <span class="hlt">Aerosols</span> are dispersions of particles in a gas, and the coupling of the two phases results in highly dynamic systems where chemical and physical properties like size, composition, phase, and refractive index change rapidly in response to environmental perturbations. <span class="hlt">Aerosol</span> particles span a wide range of sizes from 1 nm to tens of micrometres or from small molecular clusters that may more closely resemble gas phase molecules to large particles that can have similar qualities to bulk materials. However, even large particles with finite volumes exhibit distinct properties from the bulk condensed phase, due in part to their higher surface-to-volume ratio and their ability to easily access supersaturated solute states inaccessible in the bulk. <span class="hlt">Aerosols</span> represent a major challenge for study because of the facile coupling between the particle and gas, the small amounts of sample available for analysis, and the sheer breadth of operative processes. Time scales of <span class="hlt">aerosol</span> processes can be as short as nanoseconds or as long as years. Despite their very different impacts and applications, fundamental chemical physics processes serve as a common theme that underpins our understanding of <span class="hlt">aerosols</span>. This perspective article discusses challenges in the study of <span class="hlt">aerosols</span> and highlights recent chemical physics advancements that have enabled improved understanding of these complex systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020008666','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020008666"><span><span class="hlt">Aerosol</span> Radiative Forcing Derived From SeaWIFS - Retrieved <span class="hlt">Aerosol</span> Optical Properties</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chou, Mong-Dah; Chan, Pui-King; Wang, Menghua; Einaudi, Franco (Technical Monitor)</p> <p>2000-01-01</p> <p>To understand climatic implications of <span class="hlt">aerosols</span> over global oceans, the <span class="hlt">aerosol</span> optical properties retrieved from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) are analyzed, and the effects of the <span class="hlt">aerosols</span> on the Earth's radiation budgets (<span class="hlt">aerosol</span> radiative forcing, ARF) are computed using a radiative transfer model. It is found that the distribution of the SeaWiFS-retrieved <span class="hlt">aerosol</span> optical thickness is distinctively zonal. The maximum in the equatorial region coincides with the Intertropical Convergence Zone, and the maximum in the Southern Hemispheric high latitudes coincides with the region of prevailing westerlies. The minimum <span class="hlt">aerosol</span> optical thickness is found in the subtropical high pressure regions, especially in the Southern Hemisphere. These zonal patterns clearly demonstrate the influence of atmospheric circulation on the oceanic <span class="hlt">aerosol</span> distribution. Over global oceans, <span class="hlt">aerosols</span> reduce the annual mean net downward solar flux by 5.4 W m-2 at the top of the atmosphere and by 6.1 W m-2 at the surface. The largest ARF is found in the tropical Atlantic, Arabian Sea, Bay of Bengal, the coastal regions of Southeast and East Asia, and the Southern Hemispheric high latitudes. During the period of the Indonesian big fires (September-December 1997), the cooling due to <span class="hlt">aerosols</span> is greater than 15 W m-2 at the top of the atmosphere and greater than 30 W m(exp -1) at the surface in the vicinity of the maritime continents. The atmosphere receives extra solar radiation by greater than 15 W m(exp -1) over a large area. These large changes in radiative fluxes are expected to have enhanced the atmospheric stability, weakened the atmospheric circulation, and augmented the drought condition during that period. It would be very instructive to simulate the regional climatic. The model-calculated clear sky solar flux at the top of the atmosphere is compared with that derived from the Clouds and the Earth's Radiant Energy System (CERES). The net downward solar flux of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790031093&hterms=pollution+climate+change&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dpollution%2Bclimate%2Bchange','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790031093&hterms=pollution+climate+change&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dpollution%2Bclimate%2Bchange"><span>Stratospheric <span class="hlt">aerosols</span> and climatic change</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Toon, O. B.; Pollack, J. B.</p> <p>1978-01-01</p> <p>Stratospht1ic sulfuric acid particles scatter and absorb sunlight and they scatter, absorb and emit terrestrial thermal radiation. These interactions play a role in the earth's radiation balance and therefore affect climate. The stratospheric <span class="hlt">aerosols</span> are perturbed by volcanic injection of SO2 and ash, by aircraft injection of SO2, by rocket exhaust of Al2O3 and by tropospheric mixing of particles and pollutant SO2 and COS. In order to assess the effects of these perturbations on climate, the effects of the <span class="hlt">aerosols</span> on the radiation balance must be understood and in order to understand the radiation effects the properties of the <span class="hlt">aerosols</span> must be known. The discussion covers the <span class="hlt">aerosols</span>' effect on the radiation balance. It is shown that the <span class="hlt">aerosol</span> size distribution controls whether the <span class="hlt">aerosols</span> will tend to warm or cool the earth's surface. Calculations of <span class="hlt">aerosol</span> properties, including size distribution, for various perturbation sources are carried out on the basis of an <span class="hlt">aerosol</span> model. Calculations are also presented of the climatic impact of perturbed <span class="hlt">aerosols</span> due to volcanic eruptions and Space Shuttle flights.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020041485&hterms=air+asia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dair%2Basia','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020041485&hterms=air+asia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dair%2Basia"><span>Overview of ACE-Asia Spring 2001 Investigations on <span class="hlt">Aerosol</span> Radiative Effects and Related <span class="hlt">Aerosol</span> Properties</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, Philip B.; Valero, F. P. J.; Flatau, P. J.; Bergin, M.; Holben, B.; Nakajima, T.; Pilewskie, P.; Bergstrom, R.; Hipskind, R. Stephen (Technical Monitor)</p> <p>2001-01-01</p> <p>A primary, ACE-Asia objective was to quantify the interactions between <span class="hlt">aerosols</span> and radiation in the Asia-Pacific region. Toward this end, radiometric and related <span class="hlt">aerosol</span> measurements were made from ocean, land, air and space platforms. Models that predict <span class="hlt">aerosol</span> fields guided the measurements and are helping integrate and interpret results. Companion overview's survey these measurement and modeling components. Here we illustrate how these components were combined to determine <span class="hlt">aerosol</span> radiative. impacts and their relation to <span class="hlt">aerosol</span> properties. Because clouds can obscure or change <span class="hlt">aerosol</span> direct radiative effects, aircraft and ship sorties to measure these effects depended on predicting and finding cloud-free areas and times with interesting <span class="hlt">aerosols</span> present. Pre-experiment satellite cloud climatologies, pre-flight <span class="hlt">aerosol</span> and cloud forecasts, and in-flight guidance from satellite imagery all helped achieve this. Assessments of <span class="hlt">aerosol</span> regional radiative impacts benefit from the spatiotemporal coverage of satellites, provided satellite-retrieved <span class="hlt">aerosol</span> properties are accurate. Therefore, ACE-Asia included satellite retrieval tests, as part of many comparisons to judge the consistency (closure) among, diverse measurements. Early results include: (1) Solar spectrally resolved and broadband irradiances and optical depth measurements from the C-130 aircraft and at Kosan, Korea yielded <span class="hlt">aerosol</span> radiative forcing efficiencies, permitting comparisons between efficiencies of ACE-Asia and INDOEX <span class="hlt">aerosols</span>, and between dust and "pollution" <span class="hlt">aerosols</span>. Detailed results will be presented in separate papers. (2) Based on measurements of wavelength dependent <span class="hlt">aerosol</span> optical depth (AOD) and single scattering albedo the estimated 24-h a average <span class="hlt">aerosol</span> radiative forcing efficiency at the surface for photosynthetically active radiation (400 - 700 nm) in Yulin, China is approx. 30 W sq m per AOD(500 nm). (3) The R/V Brown cruise from Honolulu to Sea of Japan sampled an <span class="hlt">aerosol</span> optical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A13K..02Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A13K..02Z"><span>Observational evidence for the <span class="hlt">aerosol</span> impact on ice cloud properties regulated by cloud/<span class="hlt">aerosol</span> types</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, B.; Gu, Y.; Liou, K. N.; Jiang, J. H.; Li, Q.; Liu, X.; Huang, L.; Wang, Y.; Su, H.</p> <p>2016-12-01</p> <p>The interactions between <span class="hlt">aerosols</span> and ice clouds (consisting only of ice) represent one of the largest uncertainties in global radiative forcing from pre-industrial time to the present. The observational evidence for the <span class="hlt">aerosol</span> impact on ice cloud properties has been quite limited and showed conflicting results, partly because previous observational studies did not consider the distinct features of different ice cloud and <span class="hlt">aerosol</span> types. Using 9-year satellite observations, we find that, for ice clouds generated from deep convection, cloud thickness, cloud optical thickness (COT), and ice cloud fraction increase and decrease with small-to-moderate and high <span class="hlt">aerosol</span> loadings, respectively. For in-situ formed ice clouds, however, the preceding cloud properties increase monotonically and more sharply with <span class="hlt">aerosol</span> loadings. The case is more complicated for ice crystal effective radius (Rei). For both convection-generated and in-situ ice clouds, the responses of Rei to <span class="hlt">aerosol</span> loadings are modulated by water vapor amount in conjunction with several other meteorological parameters, but the sensitivities of Rei to <span class="hlt">aerosols</span> under the same water vapor amount differ remarkably between the two ice cloud types. As a result, overall Rei slightly increases with <span class="hlt">aerosol</span> loading for convection-generated ice clouds, but decreases for in-situ ice clouds. When <span class="hlt">aerosols</span> are decomposed into different types, an increase in the loading of smoke <span class="hlt">aerosols</span> generally leads to a decrease in COT of convection-generated ice clouds, while the reverse is true for dust and anthropogenic pollution. In contrast, an increase in the loading of any <span class="hlt">aerosol</span> type can significantly enhance COT of in-situ ice clouds. The modulation of the <span class="hlt">aerosol</span> impacts by cloud/<span class="hlt">aerosol</span> types is demonstrated and reproduced by simulations using the Weather Research and Forecasting (WRF) model. Adequate and accurate representations of the impact of different cloud/<span class="hlt">aerosol</span> types in climate models are crucial for reducing the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A13K..02Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A13K..02Z"><span>Observational evidence for the <span class="hlt">aerosol</span> impact on ice cloud properties regulated by cloud/<span class="hlt">aerosol</span> types</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, B.; Gu, Y.; Liou, K. N.; Jiang, J. H.; Li, Q.; Liu, X.; Huang, L.; Wang, Y.; Su, H.</p> <p>2017-12-01</p> <p>The interactions between <span class="hlt">aerosols</span> and ice clouds (consisting only of ice) represent one of the largest uncertainties in global radiative forcing from pre-industrial time to the present. The observational evidence for the <span class="hlt">aerosol</span> impact on ice cloud properties has been quite limited and showed conflicting results, partly because previous observational studies did not consider the distinct features of different ice cloud and <span class="hlt">aerosol</span> types. Using 9-year satellite observations, we find that, for ice clouds generated from deep convection, cloud thickness, cloud optical thickness (COT), and ice cloud fraction increase and decrease with small-to-moderate and high <span class="hlt">aerosol</span> loadings, respectively. For in-situ formed ice clouds, however, the preceding cloud properties increase monotonically and more sharply with <span class="hlt">aerosol</span> loadings. The case is more complicated for ice crystal effective radius (Rei). For both convection-generated and in-situ ice clouds, the responses of Rei to <span class="hlt">aerosol</span> loadings are modulated by water vapor amount in conjunction with several other meteorological parameters, but the sensitivities of Rei to <span class="hlt">aerosols</span> under the same water vapor amount differ remarkably between the two ice cloud types. As a result, overall Rei slightly increases with <span class="hlt">aerosol</span> loading for convection-generated ice clouds, but decreases for in-situ ice clouds. When <span class="hlt">aerosols</span> are decomposed into different types, an increase in the loading of smoke <span class="hlt">aerosols</span> generally leads to a decrease in COT of convection-generated ice clouds, while the reverse is true for dust and anthropogenic pollution. In contrast, an increase in the loading of any <span class="hlt">aerosol</span> type can significantly enhance COT of in-situ ice clouds. The modulation of the <span class="hlt">aerosol</span> impacts by cloud/<span class="hlt">aerosol</span> types is demonstrated and reproduced by simulations using the Weather Research and Forecasting (WRF) model. Adequate and accurate representations of the impact of different cloud/<span class="hlt">aerosol</span> types in climate models are crucial for reducing the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.6996K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.6996K"><span>Ensembles of satellite <span class="hlt">aerosol</span> retrievals based on three AATSR algorithms within <span class="hlt">aerosol</span>_cci</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kosmale, Miriam; Popp, Thomas</p> <p>2016-04-01</p> <p>Ensemble techniques are widely used in the modelling community, combining different modelling results in order to reduce uncertainties. This approach could be also adapted to satellite measurements. <span class="hlt">Aerosol</span>_cci is an ESA funded project, where most of the European <span class="hlt">aerosol</span> retrieval groups work together. The different algorithms are homogenized as far as it makes sense, but remain essentially different. Datasets are compared with ground based measurements and between each other. Three AATSR algorithms (Swansea university <span class="hlt">aerosol</span> retrieval, ADV <span class="hlt">aerosol</span> retrieval by FMI and Oxford <span class="hlt">aerosol</span> retrieval ORAC) provide within this project 17 year global <span class="hlt">aerosol</span> records. Each of these algorithms provides also uncertainty information on pixel level. Within the presented work, an ensembles of the three AATSR algorithms is performed. The advantage over each single algorithm is the higher spatial coverage due to more measurement pixels per gridbox. A validation to ground based AERONET measurements shows still a good correlation of the ensemble, compared to the single algorithms. Annual mean maps show the global <span class="hlt">aerosol</span> distribution, based on a combination of the three <span class="hlt">aerosol</span> algorithms. In addition, pixel level uncertainties of each algorithm are used for weighting the contributions, in order to reduce the uncertainty of the ensemble. Results of different versions of the ensembles for <span class="hlt">aerosol</span> optical depth will be presented and discussed. The results are validated against ground based AERONET measurements. A higher spatial coverage on daily basis allows better results in annual mean maps. The benefit of using pixel level uncertainties is analysed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110013260','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110013260"><span>Using OMI Observations to Measure <span class="hlt">Aerosol</span> Absorption of Biomass Burning <span class="hlt">Aerosols</span> Above Clouds</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Torres, Omar; Bhartia, P. K.; Jethva, Hiren</p> <p>2011-01-01</p> <p>The presence of absorbing <span class="hlt">aerosol</span> layers above clouds is unambiguously detected by the TOMS/OMI UV <span class="hlt">Aerosol</span> Index (AI) that uses satellite observations at two near-UV channels. A sensitivity study using radiative transfer calculations shows that the AI signal of resulting from the presence of <span class="hlt">aerosols</span> above clouds is mainly driven by the <span class="hlt">aerosol</span> absorption optical depth and the optical depth of the underlying cloud. Based on these results, an inversion algorithm has been developed to retrieve the <span class="hlt">aerosol</span> optical depth (AOD) of <span class="hlt">aerosol</span> layers above clouds. In this presentation we will discuss the sensitivity analysis, describe the retrieval approach, and present results of applications of the retrieval method to OMI observations over the South Atlantic Ocean. Preliminary error analyses, to be discussed, indicate that the AOD can be underestimated (up to -30%) or overestimated (up to 60%) depending on algorithmic assumptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29029576','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29029576"><span>Marine <span class="hlt">Aerosols</span> and Clouds.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brooks, Sarah D; Thornton, Daniel C O</p> <p>2018-01-03</p> <p>The role of marine bioaerosols in cloud formation and climate is currently so uncertain that even the sign of the climate forcing is unclear. Marine <span class="hlt">aerosols</span> form through direct emissions and through the conversion of gas-phase emissions to <span class="hlt">aerosols</span> in the atmosphere. The composition and size of <span class="hlt">aerosols</span> determine how effective they are in catalyzing the formation of water droplets and ice crystals in clouds by acting as cloud condensation nuclei and ice nucleating particles, respectively. Marine organic <span class="hlt">aerosols</span> may be sourced both from recent regional phytoplankton blooms that add labile organic matter to the surface ocean and from long-term global processes, such as the upwelling of old refractory dissolved organic matter from the deep ocean. Understanding the formation of marine <span class="hlt">aerosols</span> and their propensity to catalyze cloud formation processes are challenges that must be addressed given the major uncertainties associated with <span class="hlt">aerosols</span> in climate models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970001690','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970001690"><span>Radiative Effects of <span class="hlt">Aerosols</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Valero, Francisco P. J.</p> <p>1996-01-01</p> <p>During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in <span class="hlt">aerosol</span> optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size-resolved <span class="hlt">aerosol</span> microphysics and chemistry. Both profiles included a pollution haze from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) <span class="hlt">aerosol</span> were determined and thermal analysis of the pollution haze indicated that the fine <span class="hlt">aerosol</span> was composed primarily of a sulfate/water mixture with a refractory soot-like core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate <span class="hlt">aerosol</span> but had significantly less effect at higher humidities. A 3 km descent through a boundary layer air mass dominated by pollutant <span class="hlt">aerosol</span> with relative humidities (RH) 10-77% yielded a close agreement between the measured and calculated <span class="hlt">aerosol</span> optical depths (550 nm) of 0.160 (+/- 0.07) and 0. 157 (+/- 0.034) respectively. During descent the <span class="hlt">aerosol</span> mass scattering coefficient per unit sulfate mass varied from about 5 to 16 m(exp 2)/g and primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4+/- 0.7 m(exp 2)/g. A subsequent descent through a Saharan dust layer located above the pollution <span class="hlt">aerosol</span> layer revealed that both layers contributed similarly to <span class="hlt">aerosol</span> optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 +/- 0.2 m(exp 2)/g. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080033606&hterms=indices+diversity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dindices%2Bdiversity','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080033606&hterms=indices+diversity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dindices%2Bdiversity"><span><span class="hlt">Aerosol</span> Absorption and Radiative Forcing</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stier, Philip; Seinfeld, J. H.; Kinne, Stefan; Boucher, Olivier</p> <p>2007-01-01</p> <p>We present a comprehensive examination of <span class="hlt">aerosol</span> absorption with a focus on evaluating the sensitivity of the global distribution of <span class="hlt">aerosol</span> absorption to key uncertainties in the process representation. For this purpose we extended the comprehensive <span class="hlt">aerosol</span>-climate model ECHAM5-HAM by effective medium approximations for the calculation of <span class="hlt">aerosol</span> effective refractive indices, updated black carbon refractive indices, new cloud radiative properties considering the effect of <span class="hlt">aerosol</span> inclusions, as well as by modules for the calculation of long-wave <span class="hlt">aerosol</span> radiative properties and instantaneous <span class="hlt">aerosol</span> forcing. The evaluation of the simulated <span class="hlt">aerosol</span> absorption optical depth with the AERONET sun-photometer network shows a good agreement in the large scale global patterns. On a regional basis it becomes evident that the update of the BC refractive indices to Bond and Bergstrom (2006) significantly improves the previous underestimation of the <span class="hlt">aerosol</span> absorption optical depth. In the global annual-mean, absorption acts to reduce the shortwave anthropogenic <span class="hlt">aerosol</span> top-of-atmosphere (TOA) radiative forcing clear-sky from -0.79 to -0.53 W m(sup -2) (33%) and all-sky from -0.47 to -0.13W m(sup -2 (72%). Our results confirm that basic assumptions about the BC refractive index play a key role for <span class="hlt">aerosol</span> absorption and radiative forcing. The effect of the usage of more accurate effective medium approximations is comparably small. We demonstrate that the diversity in the AeroCom land-surface albedo fields contributes to the uncertainty in the simulated anthropogenic <span class="hlt">aerosol</span> radiative forcings: the usage of an upper versus lower bound of the AeroCom land albedos introduces a global annual-mean TOA forcing range of 0.19W m(sup -2) (36%) clear-sky and of 0.12W m(sup -2) (92%) all-sky. The consideration of black carbon inclusions on cloud radiative properties results in a small global annual-mean all-sky absorption of 0.05W m(sup -2) and a positive TOA forcing perturbation of 0</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.A23D1572L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.A23D1572L"><span><span class="hlt">Aerosol</span> Chemical Composition and its Effects on Cloud-<span class="hlt">Aerosol</span> Interactions during the 2007 CHAPS Experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Y.; Alexander, L.; Newburn, M.; Jayne, J.; Hubbe, J.; Springston, S.; Senum, G.; Andrews, B.; Ogren, J.; Kleinman, L.; Daum, P.; Berg, L.; Berkowitz, C.</p> <p>2007-12-01</p> <p>Chemical composition of submicron <span class="hlt">aerosol</span> particles was determined using an Aerodyne Time-of-Flight <span class="hlt">Aerosol</span> Mass Spectrometer (AMS) outfitted on the DOE G-1 aircraft during the Cumulus Humilis <span class="hlt">Aerosol</span> Processing Study (CHAPS) conducted in Oklahoma City area in June 2007. The primary objective of CHAPS was to investigate the effects of urban emissions on cloud <span class="hlt">aerosol</span> interactions as a function of processing of the emissions. <span class="hlt">Aerosol</span> composition was typically determined at three different altitudes: below, in, and above cloud, in both upwind and downwind regions of the urban area. <span class="hlt">Aerosols</span> were sampled from an isokinetic inlet with an upper size cut-off of ~1.5 micrometer. During cloud passages, the AMS also sampled particles that were dried from cloud droplets collected using a counter-flow virtual impactor (CVI) sampler. The <span class="hlt">aerosol</span> mass concentrations were typically below 10 microgram per cubic meter, and were dominated by organics and sulfate. Ammonium was often less than required for complete neutralization of sulfate. <span class="hlt">Aerosol</span> nitrate levels were very low. We noted that nitrate levels were significantly enhanced in cloud droplets compared to <span class="hlt">aerosols</span>, most likely resulting from dissolution of gaseous nitric acid. Organic to sulfate ratios appeared to be lower in cloud droplets than in <span class="hlt">aerosols</span>, suggesting cloud condensation nuclei properties of <span class="hlt">aerosol</span> particles might be affected by loading and nature of the organic components in <span class="hlt">aerosols</span>. In-cloud formation of sulfate was considered unimportant because of the very low SO2 concentration in the region. A detailed examination of the sources of the <span class="hlt">aerosol</span> organic components (based on hydrocarbons determined using a proton transfer reaction mass spectrometer) and their effects on cloud formation as a function of atmospheric processing (based on the degree of oxidation of the organic components) will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A24B..01A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A24B..01A"><span><span class="hlt">Aerosol</span> Enhancements in the Upper Troposphere Over The Amazon Forest: Do Amazonian Clouds Produce <span class="hlt">Aerosols</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andreae, M. O.; Afchine, A.; Albrecht, R. I.; Artaxo, P.; Borrmann, S.; Cecchini, M. A.; Costa, A.; Dollner, M.; Fütterer, D.; Järvinen, E.; Klimach, T.; Konemann, T.; Kraemer, M.; Krüger, M. L.; Machado, L.; Mertes, S.; Pöhlker, C.; Poeschl, U.; Sauer, D. N.; Schnaiter, M.; Schneider, J.; Schulz, C.; Spanu, A.; Walser, A.; Weinzierl, B.; Wendisch, M.</p> <p>2015-12-01</p> <p>The German-Brazilian cooperative aircraft campaign ACRIDICON-CHUVA (<span class="hlt">Aerosol</span>, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems) on the German research aircraft HALO took place over the Amazon Basin in September/October 2014, with the objective of studying tropical deep convective clouds over the Amazon rainforest and their interactions with trace gases, <span class="hlt">aerosol</span> particles, and atmospheric radiation. The aircraft was equipped with about 30 remote sensing and in-situ instruments for meteorological, trace gas, <span class="hlt">aerosol</span>, cloud, precipitation, and solar radiation measurements. Fourteen research flights were conducted during this campaign. Observations during ACRIDICON-CHUVA showed high <span class="hlt">aerosol</span> concentrations in the upper troposphere (UT) over the Amazon Basin, with concentrations after normalization to standard conditions often exceeding those in the boundary layer (BL). This behavior was consistent between several <span class="hlt">aerosol</span> metrics, including condensation nuclei (CN), cloud condensation nuclei (CCN), and chemical species mass concentrations. These UT <span class="hlt">aerosols</span> were different in their composition and size distribution from the <span class="hlt">aerosol</span> in the BL, making convective transport of particles unlikely as a source. The regions in the immediate outflow of deep convective clouds were found to be depleted in <span class="hlt">aerosol</span> particles, whereas enhanced <span class="hlt">aerosol</span> number and mass concentrations were found in UT regions that had experienced outflow from deep convection in the preceding 24-48 hours. This suggests that <span class="hlt">aerosol</span> production takes place in the UT based on volatile and condensable material brought up by deep convection. Subsequently, downward mixing and transport of upper tropospheric <span class="hlt">aerosol</span> may be a source of particles to the BL, where they increase in size by the condensation of biogenic volatile organic carbon (BVOC) oxidation products. This may be an important source of <span class="hlt">aerosol</span> particles in the Amazonian BL, where <span class="hlt">aerosol</span> nucleation and new</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011rstc.book..259D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011rstc.book..259D"><span>Retrieval of <span class="hlt">Aerosol</span> Properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Leeuw, Gerrit; Kinne, Stefan; Léon, Jean-Francois; Pelon, Jacques; Rosenfeld, Daniel; Schaap, Martijn; Veefkind, Pepijn J.; Veihelmann, Ben; Winker, David M.; von Hoyningen-Huene, Wolfgang</p> <p></p> <p>Atmospheric <span class="hlt">aerosol</span> is a suspension of liquid and solid particles in air, i.e. the <span class="hlt">aerosol</span> includes both particles and its surrounding medium; in practice <span class="hlt">aerosol</span> is usually referred to as the suspended matter, i.e. the particles or the droplets, depending on their aggregation state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050177048&hterms=kaufman&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dkaufman','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050177048&hterms=kaufman&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dkaufman"><span>Overview of <span class="hlt">Aerosol</span> Distribution</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kaufman, Yoram</p> <p>2005-01-01</p> <p>Our knowledge of atmospheric <span class="hlt">aerosols</span> (smoke, pollution, dust or sea salt particles, small enough to be suspended in the air), their evolution, composition, variability in space and time and interaction with clouds and precipitation is still lacking despite decades of research. Understanding the global <span class="hlt">aerosol</span> system is fundamental for progress in climate change and hydrological cycle research. While a single instrument was used to demonstrate 50 years ago that the global CO2 levels are rising, posing threat of global warming, we need an array of satellites and field measurements coupled with chemical transport models to understand the global <span class="hlt">aerosol</span> system. This complexity of the <span class="hlt">aerosol</span> problem results from their short lifetime (1 week) and variable chemical composition. A new generation of satellites provides exciting opportunities to measure the global distribution of <span class="hlt">aerosols</span>, distinguishing natural from anthropogenic <span class="hlt">aerosol</span> and measuring their interaction with clouds and climate. I shall discuss these topics and application of the data to air quality monitoring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGC13I0780J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGC13I0780J"><span>Where Next for Marine Cloud Brightening Research?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jenkins, A. K. L.; Forster, P.</p> <p>2014-12-01</p> <p>Realistic estimates of <span class="hlt">geoengineering</span> effectiveness will be central to informed decision-making on its possible role in addressing climate change. Over the last decade, global-scale computer climate modelling of <span class="hlt">geoengineering</span> has been developing. While these developments have allowed quantitative estimates of <span class="hlt">geoengineering</span> effectiveness to be produced, the relative coarseness of the grid of these models (tens of kilometres) means that key practical details of the proposed <span class="hlt">geoengineering</span> is not always realistically captured. This is particularly true for marine cloud brightening (MCB), where both the clouds, as well as the tens-of-meters scale sea-going implementation vessels cannot be captured in detail. Previous research using cloud resolving modelling has shown that neglecting such details may lead to MCB effectiveness being overestimated by up to half. Realism of MCB effectiveness will likely improve from ongoing developments in the understanding and modelling of clouds. We also propose that realism can be increased via more specific improvements (see figure). A readily achievable example would be the reframing of previous MCB effectiveness estimates in light of the cloud resolving scale findings. Incorporation of implementation details could also be made - via parameterisation - into future global-scale modelling of MCB. However, as significant unknowns regarding the design of the MCB <span class="hlt">aerosol</span> production technique remain, resource-intensive cloud resolving computer modelling of MCB may be premature unless of broader benefit to the wider understanding of clouds. One of the most essential recommendations is for enhanced communication between climate scientists and MCB designers. This would facilitate the identification of potentially important design aspects necessary for realistic computer simulations. Such relationships could be mutually beneficial, with computer modelling potentially informing more efficient designs of the MCB implementation technique</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1036220','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1036220"><span>Evaluating Global <span class="hlt">Aerosol</span> Models and <span class="hlt">Aerosol</span> and Water Vapor Properties Near Clouds</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Richard A. Ferrare; David D. Turner</p> <p></p> <p>Project goals: (1) Use the routine surface and airborne measurements at the ARM SGP site, and the routine surface measurements at the NSA site, to continue our evaluations of model <span class="hlt">aerosol</span> simulations; (2) Determine the degree to which the Raman lidar measurements of water vapor and <span class="hlt">aerosol</span> scattering and extinction can be used to remotely characterize the <span class="hlt">aerosol</span> humidification factor; (3) Use the high temporal resolution CARL data to examine how <span class="hlt">aerosol</span> properties vary near clouds; and (4) Use the high temporal resolution CARL and Atmospheric Emitted Radiance Interferometer (AERI) data to quantify entrainment in optically thin continental cumulus clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080023335','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080023335"><span>The Time Series Technique for <span class="hlt">Aerosol</span> Retrievals over Land from MODIS: Algorithm MAIAC</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lyapustin, Alexei; Wang, Yujie</p> <p>2008-01-01</p> <p> 2.1 m channel (B7) for the purpose of <span class="hlt">aerosol</span> retrieval. Obviously, the subsequent atmospheric correction will produce the same SR in the red and blue bands as predicted, i.e. an empirical function of 2.1. In other words, the spectral, spatial and temporal variability of surface reflectance in the Blue and Red bands appears borrowed from band B7. This may have certain implications for the vegetation and global carbon analysis because the chlorophyll-sensing bands B1, B3 are effectively <span class="hlt">substituted</span> in terms of variability by band B7, which is sensitive to the plant liquid water. This chapter describes a new recently developed generic <span class="hlt">aerosol</span>-surface retrieval algorithm for MODIS. The Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm simultaneously retrieves AOT and surface bi-directional reflection factor (BRF) using the time series of MODIS measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AMTD....6.2353H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AMTD....6.2353H"><span><span class="hlt">Aerosol</span> retrieval experiments in the ESA <span class="hlt">Aerosol</span>_cci project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holzer-Popp, T.; de Leeuw, G.; Martynenko, D.; Klüser, L.; Bevan, S.; Davies, W.; Ducos, F.; Deuzé, J. L.; Graigner, R. G.; Heckel, A.; von Hoyningen-Hüne, W.; Kolmonen, P.; Litvinov, P.; North, P.; Poulsen, C. A.; Ramon, D.; Siddans, R.; Sogacheva, L.; Tanre, D.; Thomas, G. E.; Vountas, M.; Descloitres, J.; Griesfeller, J.; Kinne, S.; Schulz, M.; Pinnock, S.</p> <p>2013-03-01</p> <p>Within the ESA Climate Change Initiative (CCI) project <span class="hlt">Aerosol</span>_cci (2010-2013) algorithms for the production of long-term total column <span class="hlt">aerosol</span> optical depth (AOD) datasets from European Earth Observation sensors are developed. Starting with eight existing pre-cursor algorithms three analysis steps are conducted to improve and qualify the algorithms: (1) a series of experiments applied to one month of global data to understand several major sensitivities to assumptions needed due to the ill-posed nature of the underlying inversion problem, (2) a round robin exercise of "best" versions of each of these algorithms (defined using the step 1 outcome) applied to four months of global data to identify mature algorithms, and (3) a comprehensive validation exercise applied to one complete year of global data produced by the algorithms selected as mature based on the round robin exercise. The algorithms tested included four using AATSR, three using MERIS and one using PARASOL. This paper summarizes the first step. Three experiments were conducted to assess the potential impact of major assumptions in the various <span class="hlt">aerosol</span> retrieval algorithms. In the first experiment a common set of four <span class="hlt">aerosol</span> components was used to provide all algorithms with the same assumptions. The second experiment introduced an <span class="hlt">aerosol</span> property climatology, derived from a combination of model and sun photometer observations, as a priori information in the retrievals on the occurrence of the common <span class="hlt">aerosol</span> components and their mixing ratios. The third experiment assessed the impact of using a common nadir cloud mask for AATSR and MERIS algorithms in order to characterize the sensitivity to remaining cloud contamination in the retrievals against the baseline dataset versions. The impact of the algorithm changes was assessed for one month (September 2008) of data qualitatively by visible analysis of monthly mean AOD maps and quantitatively by comparing global daily gridded satellite data against daily</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010097737','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010097737"><span>GCM Simulations of the <span class="hlt">Aerosol</span> Indirect Effect: Sensitivity to Cloud Parameterization and <span class="hlt">Aerosol</span> Burden</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Menon, Surabi; DelGenio, Anthony D.; Koch, Dorothy; Tselioudis, George; Hansen, James E. (Technical Monitor)</p> <p>2001-01-01</p> <p>We describe the coupling of the Goddard Institute for Space Studies (GISS) general circulation model (GCM) to an online sulfur chemistry model and source models for organic matter and sea-salt that is used to estimate the <span class="hlt">aerosol</span> indirect effect. The cloud droplet number concentration is diagnosed empirically from field experiment datasets over land and ocean that observe droplet number and all three <span class="hlt">aerosol</span> types simultaneously; corrections are made for implied variations in cloud turbulence levels. The resulting cloud droplet number is used to calculate variations in droplet effective radius, which in turn allows us to predict <span class="hlt">aerosol</span> effects on cloud optical thickness and microphysical process rates. We calculate the <span class="hlt">aerosol</span> indirect effect by differencing the top-of-the-atmosphere net cloud radiative forcing for simulations with present-day vs. pre-industrial emissions. Both the first (radiative) and second (microphysical) indirect effects are explored. We test the sensitivity of our results to cloud parameterization assumptions that control the vertical distribution of cloud occurrence, the autoconversion rate, and the <span class="hlt">aerosol</span> scavenging rate, each of which feeds back significantly on the model <span class="hlt">aerosol</span> burden. The global mean <span class="hlt">aerosol</span> indirect effect for all three <span class="hlt">aerosol</span> types ranges from -1.55 to -4.36 W m(exp -2) in our simulations. The results are quite sensitive to the pre-industrial background <span class="hlt">aerosol</span> burden, with low pre-industrial burdens giving strong indirect effects, and to a lesser extent to the anthropogenic <span class="hlt">aerosol</span> burden, with large burdens giving somewhat larger indirect effects. Because of this dependence on the background <span class="hlt">aerosol</span>, model diagnostics such as albedo-particle size correlations and column cloud susceptibility, for which satellite validation products are available, are not good predictors of the resulting indirect effect.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010071589','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010071589"><span>GCM Simulations of the <span class="hlt">Aerosol</span> Indirect Effect: Sensitivity to Cloud Parameterization and <span class="hlt">Aerosol</span> Burden</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Menon, Surabi; DelGenio, Anthony D.; Koch, Dorothy; Tselioudis, George; Hansen, James E. (Technical Monitor)</p> <p>2001-01-01</p> <p>We describe the coupling of the Goddard Institute for Space Studies (GISS) general circulation model (GCM) to an online sulfur chemistry model and source models for organic matter and sea-salt that is used to estimate the <span class="hlt">aerosol</span> indirect effect. The cloud droplet number concentration is diagnosed empirically from field experiment datasets over land and ocean that observe droplet number and all three <span class="hlt">aerosol</span> types simultaneously; corrections are made for implied variations in cloud turbulence levels. The resulting cloud droplet number is used to calculate variations in droplet effective radius, which in turn allows us to predict <span class="hlt">aerosol</span> effects on cloud optical thickness and microphysical process rates. We calculate the <span class="hlt">aerosol</span> indirect effect by differencing the top-of-the-atmosphere net cloud radiative forcing for simulations with present-day vs. pre-industrial emissions. Both the first (radiative) and second (microphysical) indirect effects are explored. We test the sensitivity of our results to cloud parameterization assumptions that control the vertical distribution of cloud occurrence, the autoconversion rate, and the <span class="hlt">aerosol</span> scavenging rate, each of which feeds back significantly on the model <span class="hlt">aerosol</span> burden. The global mean <span class="hlt">aerosol</span> indirect effect for all three <span class="hlt">aerosol</span> types ranges from -1.55 to -4.36 W/sq m in our simulations. The results are quite sensitive to the pre-industrial background <span class="hlt">aerosol</span> burden, with low pre-industrial burdens giving strong indirect effects, and to a lesser extent to the anthropogenic <span class="hlt">aerosol</span> burden, with large burdens giving somewhat larger indirect effects. Because of this dependence on the background <span class="hlt">aerosol</span>, model diagnostics such as albedo-particle size correlations and column cloud susceptibility, for which satellite validation products are available, are not good predictors of the resulting indirect effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110015539','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110015539"><span>International Cooperative for <span class="hlt">Aerosol</span> Prediction Workshop on <span class="hlt">Aerosol</span> Forecast Verification</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Benedetti, Angela; Reid, Jeffrey S.; Colarco, Peter R.</p> <p>2011-01-01</p> <p>The purpose of this workshop was to reinforce the working partnership between centers who are actively involved in global <span class="hlt">aerosol</span> forecasting, and to discuss issues related to forecast verification. Participants included representatives from operational centers with global <span class="hlt">aerosol</span> forecasting requirements, a panel of experts on Numerical Weather Prediction and Air Quality forecast verification, data providers, and several observers from the research community. The presentations centered on a review of current NWP and AQ practices with subsequent discussion focused on the challenges in defining appropriate verification measures for the next generation of <span class="hlt">aerosol</span> forecast systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17375556','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17375556"><span>Nanotechnology and pharmaceutical inhalation <span class="hlt">aerosols</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Patel, A R; Vavia, P R</p> <p>2007-02-01</p> <p>Pharmaceutical inhalation <span class="hlt">aerosols</span> have been playing a crucial role in the health and well being of millions of people throughout the world for many years. The technology's continual advancement, the ease of use and the more desirable pulmonary-rather-than-needle delivery for systemic drugs has increased the attraction for the pharmaceutical <span class="hlt">aerosol</span> in recent years. But administration of drugs by the pulmonary route is technically challenging because oral deposition can be high, and variations in inhalation technique can affect the quantity of drug delivered to the lungs. Recent advances in nanotechnology, particularly drug delivery field have encouraged formulation scientists to expand their reach in solving tricky problems related to drug delivery. Moreover, application of nanotechnology to <span class="hlt">aerosol</span> science has opened up a new category of pharmaceutical <span class="hlt">aerosols</span> (collectively known as nanoenabled-<span class="hlt">aerosols</span>) with added advantages and effectiveness. In this review, some of the latest approaches of nano-enabled <span class="hlt">aerosol</span> drug delivery system (including nano-suspension, trojan particles, bioadhesive nanoparticles and smart particle <span class="hlt">aerosols</span>) that can be employed successfully to overcome problems of conventional <span class="hlt">aerosol</span> systems have been introduced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70035438','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70035438"><span><span class="hlt">Geoengineering</span> and seismological aspects of the Niigata-Ken Chuetsu-Oki earthquake of 16 July 2007</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kayen, R.; Brandenberg, S.J.; CoIlins, B.D.; Dickenson, S.; Ashford, S.; Kawamata, Y.; Tanaka, Y.; Koumoto, H.; Abrahamson, N.; Cluff, L.; Tokimatsu, K.</p> <p>2009-01-01</p> <p>The M6.6 Niigata-Ken Chuetsu-Oki earthquake of 16 July 2007 occurred off the west coast of Japan with a focal depth of 10 km, immediately west of Kashiwazaki City and Kariwa Village in southern Niigata Prefecture. Peak horizontal ground accelerations of 0.68 g were measured in Kashiwazaki City, as well as at the reactor floor level of the world's largest nuclear reactor, located on the coast at Kariwa Village. Liquefaction of historic and modern river deposits, aeolian dune sand, and manmade fill was widespread in the coastal region nearest the epicenter and caused ground deformations that damaged bridges, embankments, roadways, buildings, ports, railways and utilities. Landslides along the coast of southern Niigata Prefecture and in mountainous regions inland of Kashiwazaki were also widespread affecting transportation infrastructure. Liquefaction and a landslide also damaged the nuclear power plant sites. This paper, along with a companion digital map database available at http://walrus.wr.usgs.gOv/infobank/n/nii07jp/html/n-ii-07-jp.sites.kmz, describes the seismological and <span class="hlt">geo-engineering</span> aspects of the event. ?? 2009, Earthquake Engineering Research Institute.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol32/pdf/CFR-2013-title40-vol32-sec721-10214.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol32/pdf/CFR-2013-title40-vol32-sec721-10214.pdf"><span>40 CFR 721.10214 - Poly(oxyalkylenediyl),.alpha.-<span class="hlt">substituted</span> carbomonocycle-.omega.-<span class="hlt">substituted</span> carbomonocycle...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Poly(oxyalkylenediyl),.alpha... Poly(oxyalkylenediyl),.alpha.-<span class="hlt">substituted</span> carbomonocycle-.omega.-<span class="hlt">substituted</span> carbomonocycle (generic... identified generically as poly(oxyalkylenediyl),.alpha.-<span class="hlt">substituted</span> carbomonocycle-.omega.-<span class="hlt">substituted</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol31/pdf/CFR-2011-title40-vol31-sec721-10214.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol31/pdf/CFR-2011-title40-vol31-sec721-10214.pdf"><span>40 CFR 721.10214 - Poly(oxyalkylenediyl),.alpha.-<span class="hlt">substituted</span> carbomonocycle-.omega.-<span class="hlt">substituted</span> carbomonocycle...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Poly(oxyalkylenediyl),.alpha... Poly(oxyalkylenediyl),.alpha.-<span class="hlt">substituted</span> carbomonocycle-.omega.-<span class="hlt">substituted</span> carbomonocycle (generic... identified generically as poly(oxyalkylenediyl),.alpha.-<span class="hlt">substituted</span> carbomonocycle-.omega.-<span class="hlt">substituted</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol31/pdf/CFR-2014-title40-vol31-sec721-10214.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol31/pdf/CFR-2014-title40-vol31-sec721-10214.pdf"><span>40 CFR 721.10214 - Poly(oxyalkylenediyl),.alpha.-<span class="hlt">substituted</span> carbomonocycle-.omega.-<span class="hlt">substituted</span> carbomonocycle...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Poly(oxyalkylenediyl),.alpha... Poly(oxyalkylenediyl),.alpha.-<span class="hlt">substituted</span> carbomonocycle-.omega.-<span class="hlt">substituted</span> carbomonocycle (generic... identified generically as poly(oxyalkylenediyl),.alpha.-<span class="hlt">substituted</span> carbomonocycle-.omega.-<span class="hlt">substituted</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol32/pdf/CFR-2012-title40-vol32-sec721-10214.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol32/pdf/CFR-2012-title40-vol32-sec721-10214.pdf"><span>40 CFR 721.10214 - Poly(oxyalkylenediyl),.alpha.-<span class="hlt">substituted</span> carbomonocycle-.omega.-<span class="hlt">substituted</span> carbomonocycle...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Poly(oxyalkylenediyl),.alpha... Poly(oxyalkylenediyl),.alpha.-<span class="hlt">substituted</span> carbomonocycle-.omega.-<span class="hlt">substituted</span> carbomonocycle (generic... identified generically as poly(oxyalkylenediyl),.alpha.-<span class="hlt">substituted</span> carbomonocycle-.omega.-<span class="hlt">substituted</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1253673-indirect-semi-direct-aerosol-campaign-impact-arctic-aerosols-clouds','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1253673-indirect-semi-direct-aerosol-campaign-impact-arctic-aerosols-clouds"><span>Indirect and semi-direct <span class="hlt">aerosol</span> campaign: The impact of Arctic <span class="hlt">aerosols</span> on clouds</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>McFarquhar, Greg M.; Ghan, Steven; Verlinde, Johannes; ...</p> <p>2011-02-01</p> <p>A comprehensive dataset of microphysical and radiative properties of <span class="hlt">aerosols</span> and clouds in the boundary layer in the vicinity of Barrow, Alaska, was collected in April 2008 during the Indirect and Semi-Direct <span class="hlt">Aerosol</span> Campaign (ISDAC). ISDAC's primary aim was to examine the effects of <span class="hlt">aerosols</span>, including those generated by Asian wildfires, on clouds that contain both liquid and ice. ISDAC utilized the Atmospheric Radiation Measurement Pro- gram's permanent observational facilities at Barrow and specially deployed instruments measuring <span class="hlt">aerosol</span>, ice fog, precipitation, and radiation. The National Research Council of Canada Convair-580 flew 27 sorties and collected data using an unprecedented 41more » stateof- the-art cloud and <span class="hlt">aerosol</span> instruments for more than 100 h on 12 different days. <span class="hlt">Aerosol</span> compositions, including fresh and processed sea salt, biomassburning particles, organics, and sulfates mixed with organics, varied between flights. Observations in a dense arctic haze on 19 April and above, within, and below the single-layer stratocumulus on 8 and 26 April are enabling a process-oriented understanding of how <span class="hlt">aerosols</span> affect arctic clouds. Inhomogeneities in reflectivity, a close coupling of upward and downward Doppler motion, and a nearly constant ice profile in the single-layer stratocumulus suggests that vertical mixing is responsible for its longevity observed during ISDAC. Data acquired in cirrus on flights between Barrow and Fairbanks, Alaska, are improving the understanding of the performance of cloud probes in ice. Furthermore, ISDAC data will improve the representation of cloud and <span class="hlt">aerosol</span> processes in models covering a variety of spatial and temporal scales, and determine the extent to which surface measurements can provide retrievals of <span class="hlt">aerosols</span>, clouds, precipitation, and radiative heating.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1130692-aerosol-properties-radiative-forcing-over-kanpur-during-severe-aerosol-loading-conditions','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1130692-aerosol-properties-radiative-forcing-over-kanpur-during-severe-aerosol-loading-conditions"><span><span class="hlt">Aerosol</span> Properties and Radiative Forcing over Kanpur during Severe <span class="hlt">Aerosol</span> Loading Conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kaskaoutis, D. G.; Sinha, P. R.; Vinoj, V.</p> <p>2013-11-01</p> <p>Atmospheric <span class="hlt">aerosols</span> over India exhibit large spatio-temporal fluctuation driven by the local monsoon system, emission rates and seasonally-changed air masses. The northern part of India is well-known for its high <span class="hlt">aerosol</span> loading throughout the year due to anthropogenic emissions, dust influence and biomass burning. On certain circumstances and, under favorable weather conditions, the <span class="hlt">aerosol</span> load can be severe, causing significant health concerns and climate implications. The present work analyzes the <span class="hlt">aerosol</span> episode (AE) days and examines the modification in <span class="hlt">aerosol</span> properties and radiative forcing during the period 2001-2010 based on Kanpur-AERONET sun photometer data. As AEs are considered the daysmore » having daily-mean <span class="hlt">aerosol</span> optical depth (AOD) above the decadal mean + 1 STD (standard deviation); the threshold value is defined at 0.928. The results identify 277 out of 2095 days (13.2%) of AEs over Kanpur, which are most frequently observed during post-monsoon (78 cases, 18.6%) and monsoon (76, 14.7%) seasons due to biomass-burning episodes and dust influence, respectively. On the other hand, the AEs in winter and pre-monsoon are lower in both absolute and percentage values (65, 12.5% and 58, 9.1%, respectively). The modification in <span class="hlt">aerosol</span> properties on the AE days is strongly related to season. Thus, in post-monsoon and winter the AEs are associated with enhanced presence of fine-mode <span class="hlt">aerosols</span> and Black Carbon from anthropogenic pollution and any kind of burning, while in pre-monsoon and monsoon seasons they are mostly associated with transported dust. <span class="hlt">Aerosol</span> radiative forcing (ARF) calculated using SBDART shows much more surface (~-69 to -97 Wm-2) and Top of Atmosphere cooling (-20 to -30 Wm-2) as well as atmospheric heating (~43 to 71 Wm-2) during the AE days compared to seasonal means. These forcing values are mainly controlled by the higher AODs and the modified <span class="hlt">aerosol</span> characteristics (Angstrom α, SSA) during the AE days in each season and may</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRD..116.5208B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRD..116.5208B"><span>Quantifying the response of the ORAC <span class="hlt">aerosol</span> optical depth retrieval for MSG SEVIRI to <span class="hlt">aerosol</span> model assumptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bulgin, Claire E.; Palmer, Paul I.; Merchant, Christopher J.; Siddans, Richard; Gonzi, Siegfried; Poulsen, Caroline A.; Thomas, Gareth E.; Sayer, Andrew M.; Carboni, Elisa; Grainger, Roy G.; Highwood, Eleanor J.; Ryder, Claire L.</p> <p>2011-03-01</p> <p>We test the response of the Oxford-RAL <span class="hlt">Aerosol</span> and Cloud (ORAC) retrieval algorithm for Meteosat Second Generation Spinning Enhanced Visible and InfraRed Imager (MSG SEVIRI) to changes in the <span class="hlt">aerosol</span> properties used in the dust <span class="hlt">aerosol</span> model, using data from the Dust Outflow and Deposition to the Ocean (DODO) flight campaign in August 2006. We find that using the observed DODO free tropospheric <span class="hlt">aerosol</span> size distribution and refractive index increases simulated top of the atmosphere radiance at 0.55 μm assuming a fixed <span class="hlt">aerosol</span> optical depth of 0.5 by 10-15%, reaching a maximum difference at low solar zenith angles. We test the sensitivity of the retrieval to the vertical distribution of the <span class="hlt">aerosol</span> and find that this is unimportant in determining simulated radiance at 0.55 μm. We also test the ability of the ORAC retrieval when used to produce the Glob<span class="hlt">Aerosol</span> data set to correctly identify continental <span class="hlt">aerosol</span> outflow from the African continent, and we find that it poorly constrains <span class="hlt">aerosol</span> speciation. We develop spatially and temporally resolved prior distributions of <span class="hlt">aerosols</span> to inform the retrieval which incorporates five <span class="hlt">aerosol</span> models: desert dust, maritime, biomass burning, urban, and continental. We use a Saharan Dust Index and the GEOS-Chem chemistry transport model to describe dust and biomass burning <span class="hlt">aerosol</span> outflow and compare AOD using our speciation against the Glob<span class="hlt">Aerosol</span> retrieval during January and July 2006. We find AOD discrepancies of 0.2-1 over regions of intense biomass burning outflow, where AOD from our <span class="hlt">aerosol</span> speciation and Glob<span class="hlt">Aerosol</span> speciation can differ by as much as 50-70%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A51G..08A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A51G..08A"><span>Simulating <span class="hlt">Aerosol</span> Optical Properties With the <span class="hlt">Aerosol</span> Simulation Program (ASP): Closure Studies Using ARCTAS Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alvarado, M. J.; Macintyre, H. L.; Bian, H.; Chin, M.; Wang, C.</p> <p>2012-12-01</p> <p>The scattering and absorption of ultraviolet and visible radiation by <span class="hlt">aerosols</span> can significantly alter actinic fluxes and photolysis rates. Accurate modeling of <span class="hlt">aerosol</span> optical properties is thus essential to simulating atmospheric chemistry, air quality, and climate. Here we evaluate the <span class="hlt">aerosol</span> optical property predictions of the <span class="hlt">Aerosol</span> Simulation Program (ASP) with in situ data on <span class="hlt">aerosol</span> scattering and absorption gathered during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. The model simulations are initialized with in situ data on the <span class="hlt">aerosol</span> size distribution and composition. We perform a set of sensitivity studies (e.g., internal vs. external mixture, core-in-shell versus Maxwell-Garnett, fraction of the organic carbon mass that is light-absorbing "brown carbon," etc.) to determine the model framework and parameters most consistent with the observations. We compare the ASP results to the <span class="hlt">aerosol</span> optical property lookup tables in FAST-JX and suggest improvements that will better enable FAST-JX to simulate the impact of <span class="hlt">aerosols</span> on photolysis rates and atmospheric chemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.A14C..07B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.A14C..07B"><span>Radiative Effects of <span class="hlt">Aerosol</span> in the Marine Environment: Tales from the Two-Column <span class="hlt">Aerosol</span> Project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berg, L. K.; Fast, J. D.; Barnard, J.; Chand, D.; Chapman, E. G.; Comstock, J. M.; Ferrare, R. A.; Flynn, C. J.; Hair, J. W.; Hostetler, C. A.; Hubbe, J.; Johnson, R.; Kassianov, E.; Kluzek, C.; Laskin, A.; Lee, Y.; Mei, F.; Michalsky, J. J.; Redemann, J.; Rogers, R. R.; Russell, P. B.; Sedlacek, A. J.; Schmid, B.; Shilling, J. E.; Shinozuka, Y.; Springston, S. R.; Tomlinson, J. M.; Wilson, J. M.; Zelenyuk, A.; Berkowitz, C. M.</p> <p>2013-12-01</p> <p>There is still uncertainty associated with the direct radiative forcing by atmospheric <span class="hlt">aerosol</span> and its representation in atmospheric models. This is particularly true in marine environments near the coast where the <span class="hlt">aerosol</span> loading is a function of both naturally occurring and anthropogenic <span class="hlt">aerosol</span>. These regions are also subject to variable synoptic and thermally driven flows (land-sea breezes) that transport <span class="hlt">aerosol</span> between the continental and marine environments. The situation is made more complicated due to seasonal changes in <span class="hlt">aerosol</span> emissions. Given these differences in emissions, we expect significant differences in the <span class="hlt">aerosol</span> intensive and extensive properties between summer and winter and data is needed to evaluate models over the wide range of conditions. To address this issue, the recently completed Two Column <span class="hlt">Aerosol</span> Project (TCAP) was designed to measure the key <span class="hlt">aerosol</span> parameters in two atmospheric columns, one located over Cape Cod, Massachusetts and another approximately 200 km from the coast over the Atlantic Ocean. Measurements included <span class="hlt">aerosol</span> size distribution, chemical composition, optical properties and vertical distribution. Several aspects make TCAP unique, including the year-long deployment of a suite of surface-based instruments by the US Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility and two aircraft intensive operations periods supported by the ARM Airborne Facility, one conducted in July 2012 and a second in February 2013. The presentation will include a discussion of the impact of the <span class="hlt">aerosol</span> optical properties and their uncertainty on simulations of the radiation budget within the TCAP domain in the context of both single column and regional scale models. Data from TCAP will be used to highlight a number of important factors, including diurnal variation in <span class="hlt">aerosol</span> optical depth measured at the surface site, systematic changes in <span class="hlt">aerosol</span> optical properties (including scattering, absorption, and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://medlineplus.gov/ency/patientinstructions/000746.htm','NIH-MEDLINEPLUS'); return false;" href="https://medlineplus.gov/ency/patientinstructions/000746.htm"><span>Simple, heart-smart <span class="hlt">substitutions</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>Coronary artery disease - heart smart <span class="hlt">substitutions</span>; Atherosclerosis - heart smart <span class="hlt">substitutions</span>; Cholesterol - heart smart <span class="hlt">substitutions</span>; Coronary heart disease - heart smart <span class="hlt">substitutions</span>; Healthy diet - heart ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27162963','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27162963"><span>The Impact of <span class="hlt">Aerosol</span> Particle Mixing State on the Hygroscopicity of Sea Spray <span class="hlt">Aerosol</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schill, Steven R; Collins, Douglas B; Lee, Christopher; Morris, Holly S; Novak, Gordon A; Prather, Kimberly A; Quinn, Patricia K; Sultana, Camille M; Tivanski, Alexei V; Zimmermann, Kathryn; Cappa, Christopher D; Bertram, Timothy H</p> <p>2015-06-24</p> <p><span class="hlt">Aerosol</span> particles influence global climate by determining cloud droplet number concentrations, brightness, and lifetime. Primary <span class="hlt">aerosol</span> particles, such as those produced from breaking waves in the ocean, display large particle-particle variability in chemical composition, morphology, and physical phase state, all of which affect the ability of individual particles to accommodate water and grow into cloud droplets. Despite such diversity in molecular composition, there is a paucity of methods available to assess how particle-particle variability in chemistry translates to corresponding differences in <span class="hlt">aerosol</span> hygroscopicity. Here, an approach has been developed that allows for characterization of the distribution of <span class="hlt">aerosol</span> hygroscopicity within a chemically complex population of atmospheric particles. This methodology, when applied to the interpretation of nascent sea spray <span class="hlt">aerosol</span>, provides a quantitative framework for connecting results obtained using molecular mimics generated in the laboratory with chemically complex ambient <span class="hlt">aerosol</span>. We show that nascent sea spray <span class="hlt">aerosol</span>, generated in situ in the Atlantic Ocean, displays a broad distribution of particle hygroscopicities, indicative of a correspondingly broad distribution of particle chemical compositions. Molecular mimics of sea spray <span class="hlt">aerosol</span> organic material were used in the laboratory to assess the volume fractions and molecular functionality required to suppress sea spray <span class="hlt">aerosol</span> hygroscopicity to the extent indicated by field observations. We show that proper accounting for the distribution and diversity in particle hygroscopicity and composition are important to the assessment of particle impacts on clouds and global climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120009492','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120009492"><span>Retrieving <span class="hlt">Aerosol</span> in a Cloudy Environment: <span class="hlt">Aerosol</span> Availability as a Function of Spatial and Temporal Resolution</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Remer, Lorraine A.; Mattoo, Shana; Levy, Robert C.; Heidinger, Andrew; Pierce, R. Bradley; Chin, Mian</p> <p>2011-01-01</p> <p>The challenge of using satellite observations to retrieve <span class="hlt">aerosol</span> properties in a cloudy environment is to prevent contamination of the <span class="hlt">aerosol</span> signal from clouds, while maintaining sufficient <span class="hlt">aerosol</span> product yield to satisfy specific applications. We investigate <span class="hlt">aerosol</span> retrieval availability at different instrument pixel resolutions, using the standard MODIS <span class="hlt">aerosol</span> cloud mask applied to MODIS data and a new GOES-R cloud mask applied to GOES data for a domain covering North America and surrounding oceans. <span class="hlt">Aerosol</span> availability is not the same as the cloud free fraction and takes into account the technqiues used in the MODIS algorithm to avoid clouds, reduce noise and maintain sufficient numbers of <span class="hlt">aerosol</span> retrievals. The inherent spatial resolution of each instrument, 0.5x0.5 km for MODIS and 1x1 km for GOES, is systematically degraded to 1x1 km, 2x2 km, 4x4 km and 8x8 km resolutions and then analyzed as to how that degradation would affect the availability of an <span class="hlt">aerosol</span> retrieval, assuming an <span class="hlt">aerosol</span> product resolution at 8x8 km. The results show that as pixel size increases, availability decreases until at 8x8 km 70% to 85% of the retrievals available at 0.5 km have been lost. The diurnal pattern of <span class="hlt">aerosol</span> retrieval availability examined for one day in the summer suggests that coarse resolution sensors (i.e., 4x4 km or 8x8 km) may be able to retrieve <span class="hlt">aerosol</span> early in the morning that would otherwise be missed at the time of current polar orbiting satellites, but not the diurnal <span class="hlt">aerosol</span> properties due to cloud cover developed during the day. In contrast finer resolution sensors (i.e., 1x1 km or 2x2 km) have much better opportunity to retrieve <span class="hlt">aerosols</span> in the partly cloudy scenes and better chance of returning the diurnal <span class="hlt">aerosol</span> properties. Large differences in the results of the two cloud masks designed for MODIS <span class="hlt">aerosol</span> and GOES cloud products strongly reinforce that cloud masks must be developed with specific purposes in mind and that a generic cloud mask</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ACP....18.4911G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ACP....18.4911G"><span>Primary <span class="hlt">aerosol</span> and secondary inorganic <span class="hlt">aerosol</span> budget over the Mediterranean Basin during 2012 and 2013</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guth, Jonathan; Marécal, Virginie; Josse, Béatrice; Arteta, Joaquim; Hamer, Paul</p> <p>2018-04-01</p> <p>In the frame of the Chemistry-<span class="hlt">Aerosol</span> Mediterranean Experiment (ChArMEx), we analyse the budget of primary <span class="hlt">aerosols</span> and secondary inorganic <span class="hlt">aerosols</span> over the Mediterranean Basin during the years 2012 and 2013. To do this, we use two year-long numerical simulations with the chemistry-transport model MOCAGE validated against satellite- and ground-based measurements. The budget is presented on an annual and a monthly basis on a domain covering 29 to 47° N latitude and 10° W to 38° E longitude. The years 2012 and 2013 show similar seasonal variations. The desert dust is the main contributor to the annual <span class="hlt">aerosol</span> burden in the Mediterranean region with a peak in spring, and sea salt being the second most important contributor. The secondary inorganic <span class="hlt">aerosols</span>, taken as a whole, contribute a similar level to sea salt. The results show that all of the considered <span class="hlt">aerosol</span> types, except for sea salt <span class="hlt">aerosols</span>, experience net export out of our Mediterranean Basin model domain, and thus this area should be considered as a source region for <span class="hlt">aerosols</span> globally. Our study showed that 11 % of the desert dust, 22.8 to 39.5 % of the carbonaceous <span class="hlt">aerosols</span>, 35 % of the sulfate and 9 % of the ammonium emitted or produced into the study domain are exported. The main sources of variability for <span class="hlt">aerosols</span> between 2012 and 2013 are weather-related variations, acting on emissions processes, and the episodic import of <span class="hlt">aerosols</span> from North American fires. In order to assess the importance of the anthropogenic emissions of the marine and the coastal areas which are central for the economy of the Mediterranean Basin, we made a sensitivity test simulation. This simulation is similar to the reference simulation but with the removal of the international shipping emissions and the anthropogenic emissions over a 50 km wide band inland along the coast. We showed that around 30 % of the emissions of carbonaceous <span class="hlt">aerosols</span> and 35 to 60 % of the exported carbonaceous <span class="hlt">aerosols</span> originates from the marine and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AtmEn..92..250G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AtmEn..92..250G"><span>WRF-Chem simulations of <span class="hlt">aerosols</span> and anthropogenic <span class="hlt">aerosol</span> radiative forcing in East Asia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gao, Yi; Zhao, Chun; Liu, Xiaohong; Zhang, Meigen; Leung, L. Ruby</p> <p>2014-08-01</p> <p>This study aims to provide a first comprehensive evaluation of WRF-Chem for modeling <span class="hlt">aerosols</span> and anthropogenic <span class="hlt">aerosol</span> radiative forcing (RF, including direct, semi-direct and indirect forcing) over East Asia. Several numerical experiments were conducted from November 2007 to December 2008. Comparison between model results and observations shows that the model can generally reproduce the observed spatial distributions of <span class="hlt">aerosol</span> concentration, <span class="hlt">aerosol</span> optical depth (AOD) and single scattering albedo (SSA) from measurements at many sites, including the relatively higher <span class="hlt">aerosol</span> concentration and AOD over East China and the relatively lower AOD over Southeast Asia, Korea, and Japan. The model also depicts the seasonal variation and transport of pollutions over East Asia. Particulate matter of 10 μm or less in the aerodynamic diameter (PM10), black carbon (BC), sulfate (SO42-), nitrate (NO3-) and ammonium (NH4+) concentrations are higher in spring than other seasons in Japan, which indicates the possible influence of pollutant transport from polluted area of East Asia. The model underestimates SO42- and organic carbon (OC) concentrations over mainland China by about a factor of 2, while overestimates NO3- concentration in autumn along the Yangtze River. The model captures the dust events at the Zhangye site in the semi-arid region of China. AOD is high over Southwest and Central China in winter and spring and over North China in winter, spring and summer while is low over South China in summer due to monsoon precipitation. SSA is lowest in winter and highest in summer. Anthropogenic <span class="hlt">aerosol</span> RF is estimated to range from -5 to -20 W m-2 over land and -20 to -40 W m-2 over adjacent oceans at the top of atmosphere (TOA), 5-30 W m-2 in the atmosphere (ATM) and -15 to -40 W m-2 at the bottom (BOT). The warming effect of anthropogenic <span class="hlt">aerosol</span> in ATM results from BC <span class="hlt">aerosol</span> while the negative <span class="hlt">aerosol</span> RF at TOA is caused by scattering <span class="hlt">aerosols</span> such as SO42-, NO3- and NH4</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A21K2300M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A21K2300M"><span>Sensitivity of <span class="hlt">aerosol</span> radiative forcing efficiency to the coarse mode contributions across <span class="hlt">aerosol</span> regimes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McComiskey, A. C.; Telg, H.; Sheridan, P. J.; Kassianov, E.</p> <p>2017-12-01</p> <p>The coarse mode contribution to the <span class="hlt">aerosol</span> radiative effect in a range of clean and turbid <span class="hlt">aerosol</span> regimes has not been well quantified. While the coarse-mode radiative effect in turbid conditions is generally assumed to be consequential, the effect in clean conditions has likely been underestimated. We survey ground-based in situ measurements of the coarse mode fraction of <span class="hlt">aerosol</span> optical properties measured around the globe over the past 20 years by the DOE Atmospheric Radiation Measurement Facility and the NOAA Global Monitoring Division. The <span class="hlt">aerosol</span> forcing efficiency is presented, allowing an evaluation of where the <span class="hlt">aerosol</span> coarse mode might be climatologically significant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1028128','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1028128"><span>RACORO <span class="hlt">aerosol</span> data processing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Elisabeth Andrews</p> <p>2011-10-31</p> <p>The RACORO <span class="hlt">aerosol</span> data (cloud condensation nuclei (CCN), condensation nuclei (CN) and <span class="hlt">aerosol</span> size distributions) need further processing to be useful for model evaluation (e.g., GCM droplet nucleation parameterizations) and other investigations. These tasks include: (1) Identification and flagging of 'splash' contaminated Twin Otter <span class="hlt">aerosol</span> data. (2) Calculation of actual supersaturation (SS) values in the two CCN columns flown on the Twin Otter. (3) Interpolation of CCN spectra from SGP and Twin Otter to 0.2% SS. (4) Process data for spatial variability studies. (5) Provide calculated light scattering from measured <span class="hlt">aerosol</span> size distributions. Below we first briefly describe the measurementsmore » and then describe the results of several data processing tasks that which have been completed, paving the way for the scientific analyses for which the campaign was designed. The end result of this research will be several <span class="hlt">aerosol</span> data sets which can be used to achieve some of the goals of the RACORO mission including the enhanced understanding of cloud-<span class="hlt">aerosol</span> interactions and improved cloud simulations in climate models.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16131063','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16131063"><span><span class="hlt">Aerosol</span> counterflow two-jets unit for continuous measurement of the soluble fraction of atmospheric <span class="hlt">aerosols</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mikuska, Pavel; Vecera, Zbynek</p> <p>2005-09-01</p> <p>A new type of <span class="hlt">aerosol</span> collector employing a liquid at laboratory temperature for continuous sampling of atmospheric particles is described. The collector operates on the principle of a Venturi scrubber. Sampled air flows at high linear velocity through two Venturi nozzles "atomizing" the liquid to form two jets of a polydisperse <span class="hlt">aerosol</span> of fine droplets situated against each other. Counterflow jets of droplets collide, and within this process, the <span class="hlt">aerosol</span> particles are captured into dispersed liquid. Under optimum conditions (air flow rate of 5 L/min and water flow rate of 2 mL/min), <span class="hlt">aerosol</span> particles down to 0.3 microm in diameter are quantitatively collected in the collector into deionized water while the collection efficiency of smaller particles decreases. There is very little loss of fine <span class="hlt">aerosol</span> within the <span class="hlt">aerosol</span> counterflow two-jets unit (ACTJU). Coupling of the <span class="hlt">aerosol</span> collector with an annular diffusion denuder located upstream of the collector ensures an artifact-free sampling of atmospheric <span class="hlt">aerosols</span>. Operation of the ACTJU in combination with on-line detection devices allows in situ automated analysis of water-soluble <span class="hlt">aerosol</span> species (e.g., NO2-, NO3-)with high time resolution (as high as 1 s). Under the optimum conditions, the limit of detection for particulate nitrite and nitrate is 28 and 77 ng/m(3), respectively. The instrument is sufficiently rugged for its application at routine monitoring of <span class="hlt">aerosol</span> composition in the real time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GMDD....6.4207K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GMDD....6.4207K"><span>Reallocation in modal <span class="hlt">aerosol</span> models: impacts on predicting <span class="hlt">aerosol</span> radiative effects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Korhola, T.; Kokkola, H.; Korhonen, H.; Partanen, A.-I.; Laaksonen, A.; Lehtinen, K. E. J.; Romakkaniemi, S.</p> <p>2013-08-01</p> <p>In atmospheric modelling applications the <span class="hlt">aerosol</span> particle size distribution is commonly represented by modal approach, in which particles in different size ranges are described with log-normal modes within predetermined size ranges. Such method includes numerical reallocation of particles from a mode to another for example during particle growth, leading to potentially artificial changes in the <span class="hlt">aerosol</span> size distribution. In this study we analysed how this reallocation affects climatologically relevant parameters: cloud droplet number concentration, <span class="hlt">aerosol</span>-cloud interaction coefficient and light extinction coefficient. We compared these parameters between a modal model with and without reallocation routines, and a high resolution sectional model that was considered as a reference model. We analysed the relative differences of the parameters in different experiments that were designed to cover a wide range of dynamic <span class="hlt">aerosol</span> processes occurring in the atmosphere. According to our results, limiting the allowed size ranges of the modes and the following numerical remapping of the distribution by reallocation, leads on average to underestimation of cloud droplet number concentration (up to 100%) and overestimation of light extinction (up to 20%). The analysis of <span class="hlt">aerosol</span> first indirect effect is more complicated as the ACI parameter can be either over- or underestimated by the reallocating model, depending on the conditions. However, for example in the case of atmospheric new particle formation events followed by rapid particle growth, the reallocation can cause around average 10% overestimation of the ACI parameter. Thus it is shown that the reallocation affects the ability of a model to estimate <span class="hlt">aerosol</span> climate effects accurately, and this should be taken into account when using and developing <span class="hlt">aerosol</span> models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20160009531&hterms=Remote+sensing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DRemote%2Bsensing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20160009531&hterms=Remote+sensing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DRemote%2Bsensing"><span>New Satellite Project <span class="hlt">Aerosol</span>-UA: Remote Sensing of <span class="hlt">Aerosols</span> in the Terrestrial Atmosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Milinevsky, G.; Yatskiv, Ya.; Degtyaryov, O.; Syniavskyi, I.; Mishchenko, Michael I.; Rosenbush, V.; Ivanov, Yu.; Makarov, A.; Bovchaliuk, A.; Danylevsky, V.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20160009531'); toggleEditAbsImage('author_20160009531_show'); toggleEditAbsImage('author_20160009531_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20160009531_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20160009531_hide"></p> <p>2016-01-01</p> <p>We discuss the development of the Ukrainian space project <span class="hlt">Aerosol</span>-UA which has the following three main objectives: (1) to monitor the spatial distribution of key characteristics of terrestrial tropospheric and stratospheric <span class="hlt">aerosols</span>; (2) to provide a comprehensive observational database enabling accurate quantitative estimates of the <span class="hlt">aerosol</span> contribution to the energy budget of the climate system; and (3) quantify the contribution of anthropogenic <span class="hlt">aerosols</span> to climate and ecological processes. The remote sensing concept of the project is based on precise orbital measurements of the intensity and polarization of sunlight scattered by the atmosphere and the surface with a scanning polarimeter accompanied by a wide-angle multispectral imager-polarimeter. Preparations have already been made for the development of the instrument suite for the <span class="hlt">Aerosol</span>-UA project, in particular, of the multi-channel scanning polarimeter (ScanPol) designed for remote sensing studies of the global distribution of <span class="hlt">aerosol</span> and cloud properties (such as particle size, morphology, and composition) in the terrestrial atmosphere by polarimetric and spectrophotometric measurements of the scattered sunlight in a wide range of wavelengths and viewing directions from which a scene location is observed. ScanPol is accompanied by multispectral wide-angle imager-polarimeter (MSIP) that serves to collect information on cloud conditions and Earths surface image. Various components of the polarimeter ScanPol have been prototyped, including the opto-mechanical and electronic assemblies and the scanning mirror controller. Preliminary synthetic data simulations for the retrieval of <span class="hlt">aerosol</span> parameters over land surfaces have been performed using the Generalized Retrieval of <span class="hlt">Aerosol</span> and Surface Properties (GRASP) algorithm. Methods for the validation of satellite data using ground-based observations of <span class="hlt">aerosol</span> properties are also discussed. We assume that designing, building, and launching into orbit a multi</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16139453','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16139453"><span>Stability and characterization of perphenazine <span class="hlt">aerosols</span> generated using the capillary <span class="hlt">aerosol</span> generator.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Xihao; Blondino, Frank E; Hindle, Michael; Soine, William H; Byron, Peter R</p> <p>2005-10-13</p> <p>Perphenazine (a potent antiemetic) was <span class="hlt">aerosolized</span> using capillary <span class="hlt">aerosol</span> generator to generate respirable condensation <span class="hlt">aerosols</span> from drug in propylene glycol (PG) solutions, by pumping the liquids through a heated capillary tube. The study characterized the stability of perphenazine during and following <span class="hlt">aerosol</span> generation. The stability-indicating HPLC method (C-8 column with a mobile phase of 52% 0.01 M pH 3.0 acetate buffer+48% acetonitrile) also enabled the study of perphenazine stability in solution under acidic, basic, oxidizing and photolysing conditions. An LC-MS (ESI+) method was used to characterize the degradation products. Perphenazine was found to be stable in acidic and basic conditions, while perphenazine sulfoxide was the major product formed in dilute peroxide solutions. Two photo-degradation products were formed in PG that were tentatively identified by LC-MS; one of these was synthesized and confirmed to be 2-[4-(3-phenothiazin-10-yl-propyl)-piperazino]-ethanol. Both photolysis products showed that aromatic dechlorination had occurred and one appeared to also result from interaction with the solvent. Within an <span class="hlt">aerosolization</span> energy window of 84-95 J, fine particle <span class="hlt">aerosols</span> were generated from perphenazine PG formulations with no significant degradation. Small amounts of degradation products were produced in all samples during <span class="hlt">aerosolization</span> at elevated (non-optimal) energies. These were largely consistent with those seen to result from oxidation and photolysis in solution, showing that oxidation and dehalogenation appeared to be the main degradation pathways followed when the CAG system was overheated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5389461','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5389461"><span>Development of Portable <span class="hlt">Aerosol</span> Mobility Spectrometer for Personal and Mobile <span class="hlt">Aerosol</span> Measurement</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kulkarni, Pramod; Qi, Chaolong; Fukushima, Nobuhiko</p> <p>2017-01-01</p> <p>We describe development of a Portable <span class="hlt">Aerosol</span> Mobility Spectrometer (PAMS) for size distribution measurement of submicrometer <span class="hlt">aerosol</span>. The spectrometer is designed for use in personal or mobile <span class="hlt">aerosol</span> characterization studies and measures approximately 22.5 × 22.5 × 15 cm and weighs about 4.5 kg including the battery. PAMS uses electrical mobility technique to measure number-weighted particle size distribution of <span class="hlt">aerosol</span> in the 10–855 nm range. <span class="hlt">Aerosol</span> particles are electrically charged using a dual-corona bipolar corona charger, followed by classification in a cylindrical miniature differential mobility analyzer. A condensation particle counter is used to detect and count particles. The mobility classifier was operated at an <span class="hlt">aerosol</span> flow rate of 0.05 L/min, and at two different user-selectable sheath flows of 0.2 L/min (for wider size range 15–855 nm) and 0.4 L/min (for higher size resolution over the size range of 10.6–436 nm). The instrument was operated in voltage stepping mode to retrieve the size distribution, which took approximately 1–2 minutes, depending on the configuration. Sizing accuracy and resolution were probed and found to be within the 25% limit of NIOSH criterion for direct-reading instruments (NIOSH 2012). Comparison of size distribution measurements from PAMS and other commercial mobility spectrometers showed good agreement. The instrument offers unique measurement capability for on-person or mobile size distribution measurements of ultrafine and nanoparticle <span class="hlt">aerosol</span>. PMID:28413241</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1169526','SCIGOV-DOEDE'); return false;" href="https://www.osti.gov/servlets/purl/1169526"><span>Direct <span class="hlt">Aerosol</span> Forcing Uncertainty</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Mccomiskey, Allison</p> <p>2008-01-15</p> <p>Understanding sources of uncertainty in <span class="hlt">aerosol</span> direct radiative forcing (DRF), the difference in a given radiative flux component with and without <span class="hlt">aerosol</span>, is essential to quantifying changes in Earth's radiation budget. We examine the uncertainty in DRF due to measurement uncertainty in the quantities on which it depends: <span class="hlt">aerosol</span> optical depth, single scattering albedo, asymmetry parameter, solar geometry, and surface albedo. Direct radiative forcing at the top of the atmosphere and at the surface as well as sensitivities, the changes in DRF in response to unit changes in individual <span class="hlt">aerosol</span> or surface properties, are calculated at three locations representing distinct <span class="hlt">aerosol</span> types and radiative environments. The uncertainty in DRF associated with a given property is computed as the product of the sensitivity and typical measurement uncertainty in the respective <span class="hlt">aerosol</span> or surface property. Sensitivity and uncertainty values permit estimation of total uncertainty in calculated DRF and identification of properties that most limit accuracy in estimating forcing. Total uncertainties in modeled local diurnally averaged forcing range from 0.2 to 1.3 W m-2 (42 to 20%) depending on location (from tropical to polar sites), solar zenith angle, surface reflectance, <span class="hlt">aerosol</span> type, and <span class="hlt">aerosol</span> optical depth. The largest contributor to total uncertainty in DRF is usually single scattering albedo; however decreasing measurement uncertainties for any property would increase accuracy in DRF. Comparison of two radiative transfer models suggests the contribution of modeling error is small compared to the total uncertainty although comparable to uncertainty arising from some individual properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900002762','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900002762"><span><span class="hlt">Aerosol</span> in the Pacific troposphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Clarke, Antony D.</p> <p>1989-01-01</p> <p>The use of near real-time optical techniques is emphasized for the measurement of mid-tropospheric <span class="hlt">aerosol</span> over the Central Pacific. The primary focus is on measurement of the <span class="hlt">aerosol</span> size distribution over the range of particle diameters from 0.15 to 5.0 microns that are essential for modeling CO2 backscatter values in support of the laser atmospheric wind sounder (LAWS) program. The measurement system employs a LAS-X (Laser <span class="hlt">Aerosol</span> Spectrometer-PMS, Boulder, CO) with a custom 256 channel pulse height analyzer and software for detailed measurement and analysis of <span class="hlt">aerosol</span> size distributions. A thermal preheater system (Thermo Optic <span class="hlt">Aerosol</span> Descriminator (TOAD) conditions the <span class="hlt">aerosol</span> in a manner that allows the discrimination of the size distribution of individual <span class="hlt">aerosol</span> components such as sulfuric acid, sulfates and refractory species. This allows assessment of the relative contribution of each component to the BCO2 signal. This is necessary since the different components have different sources, exhibit independent variability and provide different BCO2 signals for a given mass and particle size. Field activities involve experiments designed to examine both temporal and spatial variability of these <span class="hlt">aerosol</span> components from ground based and aircraft platforms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGC21H1180L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGC21H1180L"><span>Background <span class="hlt">aerosol</span> over the Himalayas and Tibetan Plateau: observed characteristics of <span class="hlt">aerosol</span> mass loading</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, B.; Cong, Z.; Wang, Y.; Xin, J.; Wan, X.; Pan, Y.; Liu, Z.; Wang, Y.; Zhang, G.; Kang, S.</p> <p>2016-12-01</p> <p>To investigate the atmospheric <span class="hlt">aerosols</span> of the Himalayas and Tibetan Plateau (HTP), an observation network was established within the region's various ecosystems, including at Ngari, Qomolangma (QOMS), Nam Co, and SouthEastern Tibetan (SET) stations. In this paper we illustrate <span class="hlt">aerosol</span> mass loadings by integrating in situ measurements with satellite and ground-based remote sensing datasets for the 2011-2013 period, on both local and large scales. Mass concentrations of these surface atmospheric <span class="hlt">aerosols</span> were relatively low and varied with land cover, showing a general tendency of Ngari and QOMS (barren sites) > Nam Co (grassland site) > SET (forest site). Bimodal mass distributions of size-segregated particles were found at all sites, with a relatively small peak in accumulation mode and a more notable peak in coarse mode. Diurnal variations in fine <span class="hlt">aerosol</span> masses generally displayed a bi-peak pattern at the QOMS, Nam Co and SET stations and a single-peak pattern at the Ngari station, controlled by the effects of local geomorphology, mountain-valley breeze circulation and <span class="hlt">aerosol</span> emissions. Combining surface <span class="hlt">aerosols</span> data and atmospheric-column <span class="hlt">aerosol</span> optical properties, the TSP mass and <span class="hlt">aerosol</span> optical depth (AOD) of the Multi-angle Imaging Spectroradiometer (MISR) generally decreased as land cover changed from barren to forest, in inverse relation to the PM2.5 ratios. The seasonality of <span class="hlt">aerosol</span> mass parameters was land-cover dependent. Over forest and grassland areas, TSP mass, PM2.5 mass, MISR-AOD and fine-mode AOD were higher in spring and summer, followed by relatively lower values in autumn and winter. At the barren site (the QOMS station), there were inconsistent seasonal variations between surface TSP mass (PM2.5 mass) and atmospheric column AOD (fine-mode AOD). Our findings implicate that, HTP <span class="hlt">aerosol</span> masses (especially their reginal characteristics and fine particle emissions) need to be treated sensitively in relation to assessments of their climatic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120010646','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120010646"><span>An Analysis of AERONET <span class="hlt">Aerosol</span> Absorption Properties and Classifications Representative of <span class="hlt">Aerosol</span> Source Regions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Giles, David M.; Holben, Brent N.; Eck, Thomas F.; Sinyuk, Aliaksandr; Smirnov, Alexander; Slutsker, Ilya; Dickerson, R. R.; Thompson, A. M.; Schafer, J. S.</p> <p>2012-01-01</p> <p>Partitioning of mineral dust, pollution, smoke, and mixtures using remote sensing techniques can help improve accuracy of satellite retrievals and assessments of the <span class="hlt">aerosol</span> radiative impact on climate. Spectral <span class="hlt">aerosol</span> optical depth (tau) and single scattering albedo (omega (sub 0) ) from <span class="hlt">Aerosol</span> Robotic Network (AERONET) measurements are used to form absorption [i.e., omega (sub 0) and absorption Angstrom exponent (alpha(sub abs))] and size [i.e., extinction Angstrom exponent (alpha(sub ext)) and fine mode fraction of tau] relationships to infer dominant <span class="hlt">aerosol</span> types. Using the long-term AERONET data set (1999-2010), 19 sites are grouped by <span class="hlt">aerosol</span> type based on known source regions to: (1) determine the average omega (sub 0) and alpha(sub abs) at each site (expanding upon previous work); (2) perform a sensitivity study on alpha(sub abs) by varying the spectral omega (sub 0); and (3) test the ability of each absorption and size relationship to distinguish <span class="hlt">aerosol</span> types. The spectral omega (sub 0) averages indicate slightly more <span class="hlt">aerosol</span> absorption (i.e., a 0.0 < delta omega (sub 0) <= 0.02 decrease) than in previous work and optical mixtures of pollution and smoke with dust show stronger absorption than dust alone. Frequency distributions of alpha(sub abs) show significant overlap among <span class="hlt">aerosol</span> type categories and at least 10% of the alpha(sub abs) retrievals in each category are below 1.0. Perturbing the spectral omega (sub 0) by +/- 0.03 induces significant alpha(sub abs) changes from the unperturbed value by at least approx. +/- 0.6 for Dust, approx. +/-0.2 for Mixed, and approx. +/-0.1 for Urban/Industrial and Biomass Burning. The omega (sub 0)440nm and alpha(sub ext) 440-870nm relationship shows the best separation among <span class="hlt">aerosol</span> type clusters, providing a simple technique for determining <span class="hlt">aerosol</span> type from surface- and future space-based instrumentation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000094520&hterms=pollution+climate+change&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dpollution%2Bclimate%2Bchange','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000094520&hterms=pollution+climate+change&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dpollution%2Bclimate%2Bchange"><span>Remote Sensing of <span class="hlt">Aerosol</span> and <span class="hlt">Aerosol</span> Radiative Forcing of Climate from EOS Terra MODIS Instrument</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kaufman, Yoram; Tanre, Didier; Remer, Lorraine; Einaudi, Franco (Technical Monitor)</p> <p>2000-01-01</p> <p>The recent launch of EOS-Terra into polar orbit has begun to revolutionize remote sensing of <span class="hlt">aerosol</span> and their effect on climate. Terra has five instruments, two of them,Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging Spectro-Radiometer (MISR) are designed to monitor global <span class="hlt">aerosol</span> in two different complementary ways. Here we shall discuss the use of the multispectral measurements of MODIS to derive: (1) the global distribution of <span class="hlt">aerosol</span> load (and optical thickness) over ocean and land; (2) to measure the impact of <span class="hlt">aerosol</span> on reflection of sunlight to space; and (3) to measure the ability of <span class="hlt">aerosol</span> to absorb solar radiation. These measurements have direct applications on the understanding of the effect of <span class="hlt">aerosol</span> on climate, the ability to predict climate change, and on the monitoring of dust episodes and man-made pollution. Principles of remote sensing of <span class="hlt">aerosol</span> from MODIS will be discussed and first examples of measurements from MODIS will be provided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AtmEn.118..135B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AtmEn.118..135B"><span>Sugars in Antarctic <span class="hlt">aerosol</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barbaro, Elena; Kirchgeorg, Torben; Zangrando, Roberta; Vecchiato, Marco; Piazza, Rossano; Barbante, Carlo; Gambaro, Andrea</p> <p>2015-10-01</p> <p>The processes and transformations occurring in the Antarctic <span class="hlt">aerosol</span> during atmospheric transport were described using selected sugars as source tracers. Monosaccharides (arabinose, fructose, galactose, glucose, mannose, ribose, xylose), disaccharides (sucrose, lactose, maltose, lactulose), alcohol-sugars (erythritol, mannitol, ribitol, sorbitol, xylitol, maltitol, galactitol) and anhydrosugars (levoglucosan, mannosan and galactosan) were measured in the Antarctic <span class="hlt">aerosol</span> collected during four different sampling campaigns. For quantification, a sensitive high-pressure anion exchange chromatography was coupled with a single quadrupole mass spectrometer. The method was validated, showing good accuracy and low method quantification limits. This study describes the first determination of sugars in the Antarctic <span class="hlt">aerosol</span>. The total mean concentration of sugars in the <span class="hlt">aerosol</span> collected at the ;Mario Zucchelli; coastal station was 140 pg m-3; as for the <span class="hlt">aerosol</span> collected over the Antarctic plateau during two consecutive sampling campaigns, the concentration amounted to 440 and 438 pg m-3. The study of particle-size distribution allowed us to identify the natural emission from spores or from sea-spray as the main sources of sugars in the coastal area. The enrichment of sugars in the fine fraction of the <span class="hlt">aerosol</span> collected on the Antarctic plateau is due to the degradation of particles during long-range atmospheric transport. The composition of sugars in the coarse fraction was also investigated in the <span class="hlt">aerosol</span> collected during the oceanographic cruise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000013616&hterms=four+seasons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dfour%2Bseasons','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000013616&hterms=four+seasons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dfour%2Bseasons"><span>Global <span class="hlt">Aerosol</span> Radiative Forcing Derived from Sea WiFS-Inferred <span class="hlt">Aerosol</span> Optical Properties</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chou, Ming-Dah; Chan, Pui-King; Wang, Menghua</p> <p>1999-01-01</p> <p><span class="hlt">Aerosol</span> optical properties inferred from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) radiance measurements are used to compute the <span class="hlt">aerosol</span> shortwave radiative forcing using a radiative transfer model. The <span class="hlt">aerosol</span> optical thickness at the wavelength of 865-nm is taken from the SeaWIFS archive. It is found that the nominal optical thickness over oceans ranges from 0.1 to 0.2. Using a maritime <span class="hlt">aerosol</span> model and the radiances measured at the various SeaWiFS channels, the Angstrom exponent is determined to be 0.2174, the single-scattering albedo to be 0.995, and the asymmetry factor to be 0.786. The radiative transfer model has eight bands in the visible and ultraviolet spectral regions and three bands in the near infrared. It includes the absorption due to <span class="hlt">aerosols</span>, water vapor, carbon dioxide, and oxygen, and the scattering due to <span class="hlt">aerosols</span> and gases (Rayleigh scattering). The radiative forcing is computed over global oceans for four months (January, April, July, and October, 1998) to represent four seasons. It is found that the <span class="hlt">aerosol</span> radiative forcing is large and changes significantly with seasons near the continents with large-scale forest fires and desert dust. Averaged over oceans and the four months, the <span class="hlt">aerosol</span> radiative forcing is approximately 7 W/sq m at the top of the atmosphere. This large radiative forcing is expected to have a significant cooling effect on the Earth's climate as implied from simulations of a number of general circulation models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/965630-modeling-atmospheric-aerosols-wrf-chem','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/965630-modeling-atmospheric-aerosols-wrf-chem"><span>Modeling Atmospheric <span class="hlt">Aerosols</span> in WRF/Chem</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Zhang, Yang; Hu, X.-M.; Howell, G.</p> <p>2005-06-01</p> <p>In this study, three <span class="hlt">aerosol</span> modules are tested and compared. The first module is the Modal <span class="hlt">Aerosol</span> Dynamics Model for Europe (MADE) with the secondary organic <span class="hlt">aerosol</span> model (SORGAM) (referred to as MADE/SORGAM). The second module is the Model for Simulating <span class="hlt">Aerosol</span> Interactions and Chemistry (MOSAIC). The third module is the Model of <span class="hlt">Aerosol</span> Dynamics, Reaction, Ionization and Dissolution (MADRID). The three modules differ in terms of size representation used, chemical species treated, assumptions and numerical algorithms used. Table 1 compares the major processes among the three <span class="hlt">aerosol</span> modules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6283819','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/6283819"><span>Improved solid <span class="hlt">aerosol</span> generator</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Prescott, D.S.; Schober, R.K.; Beller, J.</p> <p>1988-07-19</p> <p>An improved solid <span class="hlt">aerosol</span> generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid <span class="hlt">aerosol</span> generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated <span class="hlt">aerosol</span> in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=System+AND+automated&pg=7&id=EJ965919','ERIC'); return false;" href="https://eric.ed.gov/?q=System+AND+automated&pg=7&id=EJ965919"><span>How Do <span class="hlt">Substitute</span> Teachers <span class="hlt">Substitute</span>? An Empirical Study of <span class="hlt">Substitute</span>-Teacher Labor Supply</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Gershenson, Seth</p> <p>2012-01-01</p> <p>This paper examines the daily labor supply of a potentially important, but often overlooked, source of instruction in U.S. public schools: <span class="hlt">substitute</span> teachers. I estimate a sequential binary-choice model of <span class="hlt">substitute</span> teachers' job-offer acceptance decisions using data on job offers made by a randomized automated calling system. Importantly, this…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.7648K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.7648K"><span>Comparison of MADE3-simulated and observed <span class="hlt">aerosol</span> distributions with a focus on <span class="hlt">aerosol</span> vertical profiles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaiser, Christopher; Hendricks, Johannes; Righi, Mattia; Jöckel, Patrick</p> <p>2016-04-01</p> <p>The reliability of <span class="hlt">aerosol</span> radiative forcing estimates from climate models depends on the accuracy of simulated global <span class="hlt">aerosol</span> distribution and composition, as well as on the models' representation of the <span class="hlt">aerosol</span>-cloud and <span class="hlt">aerosol</span>-radiation interactions. To help improve on previous modeling studies, we recently developed the new <span class="hlt">aerosol</span> microphysics submodel MADE3 that explicitly tracks particle mixing state in the Aitken, accumulation, and coarse mode size ranges. We implemented MADE3 into the global atmospheric chemistry general circulation model EMAC and evaluated it by comparison of simulated <span class="hlt">aerosol</span> properties to observations. Compared properties include continental near-surface <span class="hlt">aerosol</span> component concentrations and size distributions, continental and marine <span class="hlt">aerosol</span> vertical profiles, and nearly global <span class="hlt">aerosol</span> optical depth. Recent studies have shown the specific importance of <span class="hlt">aerosol</span> vertical profiles for determination of the <span class="hlt">aerosol</span> radiative forcing. Therefore, our focus here is on the evaluation of simulated vertical profiles. The observational data is taken from campaigns between 1990 and 2011 over the Pacific Ocean, over North and South America, and over Europe. The datasets include black carbon and total <span class="hlt">aerosol</span> mass mixing ratios, as well as <span class="hlt">aerosol</span> particle number concentrations. Compared to other models, EMAC with MADE3 yields good agreement with the observations - despite a general high bias of the simulated mass mixing ratio profiles. However, BC concentrations are generally overestimated by many models in the upper troposphere. With MADE3 in EMAC, we find better agreement of the simulated BC profiles with HIPPO data than the multi-model average of the models that took part in the AeroCom project. There is an interesting difference between the profiles from individual campaigns and more "climatological" datasets. For instance, compared to spatially and temporally localized campaigns, the model simulates a more continuous decline in both total</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eosweb.larc.nasa.gov/project/misr/gallery/global_aerosol_observations','SCIGOV-ASDC'); return false;" href="https://eosweb.larc.nasa.gov/project/misr/gallery/global_aerosol_observations"><span>Global <span class="hlt">Aerosol</span> Observations</span></a></p> <p><a target="_blank" href="http://eosweb.larc.nasa.gov/">Atmospheric Science Data Center </a></p> <p></p> <p>2013-04-19</p> <p>... atmosphere, directly influencing global climate and human health. Ground-based networks that accurately measure column <span class="hlt">aerosol</span> amount and ... being used to improve Air Quality Models and for regional health studies. To assess the human-health impact of chronic <span class="hlt">aerosol</span> exposure, ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990064611&hterms=How+get+human+cloud&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DHow%2Bget%2Bhuman%2Bcloud%253F','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990064611&hterms=How+get+human+cloud&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DHow%2Bget%2Bhuman%2Bcloud%253F"><span>Radiative Importance of <span class="hlt">Aerosol</span>-Cloud Interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tsay, Si-Chee</p> <p>1999-01-01</p> <p><span class="hlt">Aerosol</span> particles are input into the troposphere by biomass burning, among other sources. These <span class="hlt">aerosol</span> palls cover large expanses of the earth's surface. <span class="hlt">Aerosols</span> may directly scatter solar radiation back to space, thus increasing the earth's albedo and act to cool the earth's surface and atmosphere. <span class="hlt">Aerosols</span> also contribute to the earth's energy balance indirectly. Hygroscopic <span class="hlt">aerosol</span> act as cloud condensation nuclei (CCN) and thus affects cloud properties. In 1977, Twomey theorized that additional available CCN would create smaller but more numerous cloud droplets in a cloud with a given amount of liquid water. This in turn would increase the cloud albedo which would scatter additional radiation back to space and create a similar cooling pattern as the direct <span class="hlt">aerosol</span> effect. Estimates of the magnitude of the <span class="hlt">aerosol</span> indirect effect on a global scale range from 0.0 to -4.8 W/sq m. Thus the indirect effect can be of comparable magnitude and opposite in sign to the estimates of global greenhouse gas forcing <span class="hlt">Aerosol</span>-cloud interaction is not a one-way process. Just as <span class="hlt">aerosols</span> have an influence on clouds through the cloud microphysics, clouds have an influence on <span class="hlt">aerosols</span>. Cloud droplets are solutions of liquid water and CCN, now dissolved. When the cloud droplet evaporates it leaves behind an <span class="hlt">aerosol</span> particle. This new particle does not have to have the same properties as the original CCN. In fact, studies show that <span class="hlt">aerosol</span> particles that result from cloud processing are larger in size than the original CCN. Optical properties of <span class="hlt">aerosol</span> particles are dependent on the size of the particles. Larger particles have a smaller backscattering fraction, and thus less incoming solar radiation will be backscattered to space if the <span class="hlt">aerosol</span> particles are larger. Therefore, we see that <span class="hlt">aerosols</span> and clouds modify each other to influence the radiative balance of the earth. Understanding and quantifying the spatial and seasonal patterns of the <span class="hlt">aerosol</span> indirect forcing may have</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ACP....18.3119M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ACP....18.3119M"><span><span class="hlt">Aerosol</span>-cloud interactions in mixed-phase convective clouds - Part 1: <span class="hlt">Aerosol</span> perturbations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miltenberger, Annette K.; Field, Paul R.; Hill, Adrian A.; Rosenberg, Phil; Shipway, Ben J.; Wilkinson, Jonathan M.; Scovell, Robert; Blyth, Alan M.</p> <p>2018-03-01</p> <p>Changes induced by perturbed <span class="hlt">aerosol</span> conditions in moderately deep mixed-phase convective clouds (cloud top height ˜ 5 km) developing along sea-breeze convergence lines are investigated with high-resolution numerical model simulations. The simulations utilise the newly developed Cloud-AeroSol Interacting Microphysics (CASIM) module for the Unified Model (UM), which allows for the representation of the two-way interaction between cloud and <span class="hlt">aerosol</span> fields. Simulations are evaluated against observations collected during the COnvective Precipitation Experiment (COPE) field campaign over the southwestern peninsula of the UK in 2013. The simulations compare favourably with observed thermodynamic profiles, cloud base cloud droplet number concentrations (CDNC), cloud depth, and radar reflectivity statistics. Including the modification of <span class="hlt">aerosol</span> fields by cloud microphysical processes improves the correspondence with observed CDNC values and spatial variability, but reduces the agreement with observations for average cloud size and cloud top height. Accumulated precipitation is suppressed for higher-<span class="hlt">aerosol</span> conditions before clouds become organised along the sea-breeze convergence lines. Changes in precipitation are smaller in simulations with <span class="hlt">aerosol</span> processing. The precipitation suppression is due to less efficient precipitation production by warm-phase microphysics, consistent with parcel model predictions. In contrast, after convective cells organise along the sea-breeze convergence zone, accumulated precipitation increases with <span class="hlt">aerosol</span> concentrations. Condensate production increases with the <span class="hlt">aerosol</span> concentrations due to higher vertical velocities in the convective cores and higher cloud top heights. However, for the highest-<span class="hlt">aerosol</span> scenarios, no further increase in the condensate production occurs, as clouds grow into an upper-level stable layer. In these cases, the reduced precipitation efficiency (PE) dominates the precipitation response and no further</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ACP....1713151C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ACP....1713151C"><span>Unveiling <span class="hlt">aerosol</span>-cloud interactions - Part 1: Cloud contamination in satellite products enhances the <span class="hlt">aerosol</span> indirect forcing estimate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Christensen, Matthew W.; Neubauer, David; Poulsen, Caroline A.; Thomas, Gareth E.; McGarragh, Gregory R.; Povey, Adam C.; Proud, Simon R.; Grainger, Roy G.</p> <p>2017-11-01</p> <p>Increased concentrations of <span class="hlt">aerosol</span> can enhance the albedo of warm low-level cloud. Accurately quantifying this relationship from space is challenging due in part to contamination of <span class="hlt">aerosol</span> statistics near clouds. <span class="hlt">Aerosol</span> retrievals near clouds can be influenced by stray cloud particles in areas assumed to be cloud-free, particle swelling by humidification, shadows and enhanced scattering into the <span class="hlt">aerosol</span> field from (3-D radiative transfer) clouds. To screen for this contamination we have developed a new cloud-<span class="hlt">aerosol</span> pairing algorithm (CAPA) to link cloud observations to the nearest <span class="hlt">aerosol</span> retrieval within the satellite image. The distance between each <span class="hlt">aerosol</span> retrieval and nearest cloud is also computed in CAPA. Results from two independent satellite imagers, the Advanced Along-Track Scanning Radiometer (AATSR) and Moderate Resolution Imaging Spectroradiometer (MODIS), show a marked reduction in the strength of the intrinsic <span class="hlt">aerosol</span> indirect radiative forcing when selecting <span class="hlt">aerosol</span> pairs that are located farther away from the clouds (-0.28±0.26 W m-2) compared to those including pairs that are within 15 km of the nearest cloud (-0.49±0.18 W m-2). The larger <span class="hlt">aerosol</span> optical depths in closer proximity to cloud artificially enhance the relationship between <span class="hlt">aerosol</span>-loading, cloud albedo, and cloud fraction. These results suggest that previous satellite-based radiative forcing estimates represented in key climate reports may be exaggerated due to the inclusion of retrieval artefacts in the <span class="hlt">aerosol</span> located near clouds.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120000825','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120000825"><span>In Situ <span class="hlt">Aerosol</span> Detector</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vakhtin, Andrei; Krasnoperov, Lev</p> <p>2011-01-01</p> <p>An affordable technology designed to facilitate extensive global atmospheric <span class="hlt">aerosol</span> measurements has been developed. This lightweight instrument is compatible with newly developed platforms such as tethered balloons, blimps, kites, and even disposable instruments such as dropsondes. This technology is based on detection of light scattered by <span class="hlt">aerosol</span> particles where an optical layout is used to enhance the performance of the laboratory prototype instrument, which allows detection of smaller <span class="hlt">aerosol</span> particles and improves the accuracy of <span class="hlt">aerosol</span> particle size measurement. It has been determined that using focused illumination geometry without any apertures is advantageous over using the originally proposed collimated beam/slit geometry (that is supposed to produce uniform illumination over the beam cross-section). The illumination source is used more efficiently, which allows detection of smaller <span class="hlt">aerosol</span> particles. Second, the obtained integral scattered light intensity measured for the particle can be corrected for the beam intensity profile inhomogeneity based on the measured beam intensity profile and measured particle location. The particle location (coordinates) in the illuminated sample volume is determined based on the information contained in the image frame. The procedure considerably improves the accuracy of determination of the <span class="hlt">aerosol</span> particle size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AMT.....2..679T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AMT.....2..679T"><span>The GRAPE <span class="hlt">aerosol</span> retrieval algorithm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thomas, G. E.; Poulsen, C. A.; Sayer, A. M.; Marsh, S. H.; Dean, S. M.; Carboni, E.; Siddans, R.; Grainger, R. G.; Lawrence, B. N.</p> <p>2009-11-01</p> <p>The <span class="hlt">aerosol</span> component of the Oxford-Rutherford <span class="hlt">Aerosol</span> and Cloud (ORAC) combined cloud and <span class="hlt">aerosol</span> retrieval scheme is described and the theoretical performance of the algorithm is analysed. ORAC is an optimal estimation retrieval scheme for deriving cloud and <span class="hlt">aerosol</span> properties from measurements made by imaging satellite radiometers and, when applied to cloud free radiances, provides estimates of <span class="hlt">aerosol</span> optical depth at a wavelength of 550 nm, <span class="hlt">aerosol</span> effective radius and surface reflectance at 550 nm. The <span class="hlt">aerosol</span> retrieval component of ORAC has several incarnations - this paper addresses the version which operates in conjunction with the cloud retrieval component of ORAC (described by Watts et al., 1998), as applied in producing the Global Retrieval of ATSR Cloud Parameters and Evaluation (GRAPE) data-set. The algorithm is described in detail and its performance examined. This includes a discussion of errors resulting from the formulation of the forward model, sensitivity of the retrieval to the measurements and a priori constraints, and errors resulting from assumptions made about the atmospheric/surface state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AMTD....2..981T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AMTD....2..981T"><span>The GRAPE <span class="hlt">aerosol</span> retrieval algorithm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thomas, G. E.; Poulsen, C. A.; Sayer, A. M.; Marsh, S. H.; Dean, S. M.; Carboni, E.; Siddans, R.; Grainger, R. G.; Lawrence, B. N.</p> <p>2009-04-01</p> <p>The <span class="hlt">aerosol</span> component of the Oxford-Rutherford <span class="hlt">Aerosol</span> and Cloud (ORAC) combined cloud and <span class="hlt">aerosol</span> retrieval scheme is described and the theoretical performance of the algorithm is analysed. ORAC is an optimal estimation retrieval scheme for deriving cloud and <span class="hlt">aerosol</span> properties from measurements made by imaging satellite radiometers and, when applied to cloud free radiances, provides estimates of <span class="hlt">aerosol</span> optical depth at a wavelength of 550 nm, <span class="hlt">aerosol</span> effective radius and surface reflectance at 550 nm. The <span class="hlt">aerosol</span> retrieval component of ORAC has several incarnations - this paper addresses the version which operates in conjunction with the cloud retrieval component of ORAC (described by Watts et al., 1998), as applied in producing the Global Retrieval of ATSR Cloud Parameters and Evaluation (GRAPE) data-set. The algorithm is described in detail and its performance examined. This includes a discussion of errors resulting from the formulation of the forward model, sensitivity of the retrieval to the measurements and a priori constraints, and errors resulting from assumptions made about the atmospheric/surface state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A31A3012K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A31A3012K"><span>The Mpi-M <span class="hlt">Aerosol</span> Climatology (MAC)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kinne, S.</p> <p>2014-12-01</p> <p>Monthly gridded global data-sets for <span class="hlt">aerosol</span> optical properties (AOD, SSA and g) and for <span class="hlt">aerosol</span> microphysical properties (CCN and IN) offer a (less complex) alternate path to include <span class="hlt">aerosol</span> radiative effects and <span class="hlt">aerosol</span> impacts on cloud-microphysics in global simulations. Based on merging AERONET sun-/sky-photometer data onto background maps provided by AeroCom phase 1 modeling output and AERONET sun-/the MPI-M <span class="hlt">Aerosol</span> Climatology (MAC) version 1 was developed and applied in IPCC simulations with ECHAM and as ancillary data-set in satellite-based global data-sets. An updated version 2 of this climatology will be presented now applying central values from the more recent AeroCom phase 2 modeling and utilizing the better global coverage of trusted sun-photometer data - including statistics from the Marine <span class="hlt">Aerosol</span> network (MAN). Applications include spatial distributions of estimates for <span class="hlt">aerosol</span> direct and <span class="hlt">aerosol</span> indirect radiative effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170002305','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170002305"><span>CATS <span class="hlt">Aerosol</span> Typing and Future Directions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McGill, Matt; Yorks, John; Scott, Stan; Palm, Stephen; Hlavka, Dennis; Hart, William; Nowottnick, Ed; Selmer, Patrick; Kupchock, Andrew; Midzak, Natalie; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170002305'); toggleEditAbsImage('author_20170002305_show'); toggleEditAbsImage('author_20170002305_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170002305_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170002305_hide"></p> <p>2016-01-01</p> <p>The Cloud <span class="hlt">Aerosol</span> Transport System (CATS), launched in January of 2015, is a lidar remote sensing instrument that will provide range-resolved profile measurements of atmospheric <span class="hlt">aerosols</span> and clouds from the International Space Station (ISS). CATS is intended to operate on-orbit for at least six months, and up to three years. Status of CATS Level 2 and Plans for the Future:Version. 1. <span class="hlt">Aerosol</span> Typing (ongoing): Mode 1: L1B data released later this summer; L2 data released shortly after; Identify algorithm biases (ex. striping, FOV (field of view) biases). Mode 2: Processed Released Currently working on correcting algorithm issues. Version 2 <span class="hlt">Aerosol</span> Typing (Fall, 2016): Implementation of version 1 modifications Integrate GEOS-5 <span class="hlt">aerosols</span> for typing guidance for non spherical <span class="hlt">aerosols</span>. Version 3 <span class="hlt">Aerosol</span> Typing (2017): Implementation of 1-D Var Assimilation into GEOS-5 Dynamic lidar ratio that will evolve in conjunction with simulated <span class="hlt">aerosol</span> mixtures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020065565&hterms=monogram&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmonogram','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020065565&hterms=monogram&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmonogram"><span>Stratospheric <span class="hlt">Aerosol</span> Measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pueschel, Rudolf, F.; Gore, Warren J. (Technical Monitor)</p> <p>1998-01-01</p> <p>Stratospheric <span class="hlt">aerosols</span> affect the atmospheric energy balance by scattering and absorbing solar and terrestrial radiation. They also can alter stratospheric chemical cycles by catalyzing heterogeneous reactions which markedly perturb odd nitrogen, chlorine and ozone levels. <span class="hlt">Aerosol</span> measurements by satellites began in NASA in 1975 with the Stratospheric <span class="hlt">Aerosol</span> Measurement (SAM) program, to be followed by the Stratospheric <span class="hlt">Aerosol</span> and Gas Experiment (SAGE) starting in 1979. Both programs employ the solar occultation, or Earth limb extinction, techniques. Major results of these activities include the discovery of polar stratospheric clouds (PSCs) in both hemispheres in winter, illustrations of the impacts of major (El Chichon 1982 and Pinatubo 1991) eruptions, and detection of a negative global trend in lower stratospheric/upper tropospheric <span class="hlt">aerosol</span> extinction. This latter result can be considered a triumph of successful worldwide sulfur emission controls. The SAGE record will be continued and improved by SAGE III, currently scheduled for multiple launches beginning in 2000 as part of the Earth Observing System (EOS). The satellite program has been supplemented by in situ measurements aboard the ER-2 (20 km ceiling) since 1974, and from the DC-8 (13 km ceiling) aircraft beginning in 1989. Collection by wire impactors and subsequent electron microscopic and X-ray energy-dispersive analyses, and optical particle spectrometry have been the principle techniques. Major findings are: (1) The stratospheric background <span class="hlt">aerosol</span> consists of dilute sulfuric acid droplets of around 0.1 micrometer modal diameter at concentration of tens to hundreds of monograms per cubic meter; (2) Soot from aircraft amounts to a fraction of one percent of the background total <span class="hlt">aerosol</span>; (3) Volcanic eruptions perturb the sulfuric acid, but not the soot, <span class="hlt">aerosol</span> abundance by several orders of magnitude; (4) PSCs contain nitric acid at temperatures below 195K, supporting chemical hypotheses</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....13384B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....13384B"><span>The Global Atmosphere Watch <span class="hlt">Aerosol</span> Programme</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baltensperger, U.</p> <p>2003-04-01</p> <p>The Global Atmosphere Watch (GAW) programme is a WMO sponsored activity and currently supported by about 80 WMO member countries. It is the goal of GAW to develop and maintain long-term measurements of atmospheric constituents in order to detect trends, develop <span class="hlt">aerosol</span> predictive capabilities and understand proc- esses. With respect to <span class="hlt">aerosols</span>, the objective of GAW is to support a global network determining the spatio-temporal distribution of <span class="hlt">aerosol</span> properties related to climate forcing and air quality up to multi-decadal time scales. The GAW network consists of 22 Global stations and some 300 Regional stations. The Scientific Advisory Group (SAG) for <span class="hlt">Aerosols</span> will soon publish their recommendations for <span class="hlt">aerosol</span> measurements. Each site should have an acceptable <span class="hlt">aerosol</span> sampling inlet. Regional stations measure <span class="hlt">aerosol</span> optical depth, as well as the <span class="hlt">aerosol</span> light scattering and absorption coefficient. If possible these should be complemented by routine mass concentration and composition measurements in two <span class="hlt">aerosol</span> size fractions. At Global stations, a larger number of measurements are desirable. These include the Regional parameters list above as well as the light scattering, hemispheric backscat- tering, and absorption coefficients at various wavelengths, <span class="hlt">aerosol</span> number concen- tration, cloud condensation nuclei (CCN) concentration at 0.5% supersaturation, and diffuse, global and direct solar radiation. Additional parameters such as the <span class="hlt">aerosol</span> size distribution, detailed size fractionated chemical composition, dependence of <span class="hlt">aerosol</span> properties on relative humidity, CCN concentration at various supersatura- tions, and the vertical distribution of <span class="hlt">aerosol</span> properties should be measured intermit- tently at Global stations. Examples from the Jungfraujoch (Swiss Alps, 3580 m asl) will be given, where many of the parameters listed above are measured. Data are delivered to and made available by the World Data Centre for <span class="hlt">Aerosols</span> (WDCA, located in Ispra, Italy http</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol30/pdf/CFR-2010-title40-vol30-sec721-10126.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol30/pdf/CFR-2010-title40-vol30-sec721-10126.pdf"><span>40 CFR 721.10126 - Alkyl amino <span class="hlt">substituted</span> triazine amino <span class="hlt">substituted</span> benezenesulfonic acid reaction product with...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... <span class="hlt">substituted</span> benezenesulfonic acid reaction product with naphthalenesulfonato azo <span class="hlt">substituted</span> phenyl azo... <span class="hlt">substituted</span> triazine amino <span class="hlt">substituted</span> benezenesulfonic acid reaction product with naphthalenesulfonato azo... <span class="hlt">substituted</span> triazine amino <span class="hlt">substituted</span> benezenesulfonic acid reaction product with naphthalenesulfonato azo...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol31/pdf/CFR-2011-title40-vol31-sec721-10126.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol31/pdf/CFR-2011-title40-vol31-sec721-10126.pdf"><span>40 CFR 721.10126 - Alkyl amino <span class="hlt">substituted</span> triazine amino <span class="hlt">substituted</span> benezenesulfonic acid reaction product with...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... <span class="hlt">substituted</span> benezenesulfonic acid reaction product with naphthalenesulfonato azo <span class="hlt">substituted</span> phenyl azo... <span class="hlt">substituted</span> triazine amino <span class="hlt">substituted</span> benezenesulfonic acid reaction product with naphthalenesulfonato azo... <span class="hlt">substituted</span> triazine amino <span class="hlt">substituted</span> benezenesulfonic acid reaction product with naphthalenesulfonato azo...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A21M..05F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A21M..05F"><span>Lidar characterizations of atmospheric <span class="hlt">aerosols</span> and clouds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Burton, S. P.</p> <p>2017-12-01</p> <p>Knowledge of the vertical profile, composition, concentration, and size distribution of <span class="hlt">aerosols</span> is required to quantify the impacts of <span class="hlt">aerosols</span> on human health, global and regional climate, clouds and precipitation. In particular, radiative forcing due to anthropogenic <span class="hlt">aerosols</span> is the most uncertain part of anthropogenic radiative forcing, with <span class="hlt">aerosol</span>-cloud interactions (ACI) as the largest source of uncertainty in current estimates of global radiative forcing. Improving <span class="hlt">aerosol</span> transport model predictions of the vertical profile of <span class="hlt">aerosol</span> optical and microphysical characteristics is crucial for improving assessments of <span class="hlt">aerosol</span> radiative forcing. Understanding how <span class="hlt">aerosols</span> and clouds interact is essential for investigating the <span class="hlt">aerosol</span> indirect effect and ACI. Through its ability to provide vertical profiles of <span class="hlt">aerosol</span> and cloud distributions as well as important information regarding the optical and physical properties of <span class="hlt">aerosols</span> and clouds, lidar is a crucial tool for addressing these science questions. This presentation describes how surface, airborne, and satellite lidar measurements have been used to address these questions, and in particular how High Spectral Resolution Lidar (HSRL) measurements provide profiles of <span class="hlt">aerosol</span> properties (backscatter, extinction, depolarization, concentration, size) important for characterizing radiative forcing. By providing a direct measurement of <span class="hlt">aerosol</span> extinction, HSRL provides more accurate <span class="hlt">aerosol</span> measurement profiles and more accurate constraints for models than standard retrievals from elastic backscatter lidar, which loses accuracy and precision at lower altitudes due to attenuation from overlying layers. Information regarding particle size and abundance from advanced lidar retrievals provides better proxies for cloud-condensation-nuclei (CCN), which are required for assessing <span class="hlt">aerosol</span>-cloud interactions. When combined with data from other sensors, advanced lidar measurements can provide information on <span class="hlt">aerosol</span> and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.A33B0979H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.A33B0979H"><span>Seasonality of Forcing by Carbonaceous <span class="hlt">Aerosols</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Habib, G.; Bond, T.; Rasch, P. J.; Coleman, D.</p> <p>2006-12-01</p> <p><span class="hlt">Aerosols</span> can influence the energy balance of Earth-Atmosphere system with profound effect on regional climate. Atmospheric processes, such as convection, scavenging, wet and dry deposition, govern the lifetime and location of <span class="hlt">aerosol</span>; emissions affect its quantity and location. Both affect climate forcing. Here we investigate the effect of seasonality in emissions and atmospheric processes on radiative forcing by carbonaceous <span class="hlt">aerosols</span>, focusing on <span class="hlt">aerosol</span> from fossil fuel and biofuel. Because <span class="hlt">aerosol</span> lifetime is seasonal, ignoring the seasonality of sources such as residential biofuel may introduce a bias in <span class="hlt">aerosol</span> burden and therefore in predicted climate forcing. We present a global emission inventory of carbonaceous <span class="hlt">aerosols</span> with seasonality, and simulate atmospheric concentrations using the Community Atmosphere Model (CAM). We discuss where and when the seasonality of emissions and atmospheric processes has strong effects on atmospheric burden, lifetime, climate forcing and <span class="hlt">aerosol</span> optical depth (AOD). Previous work has shown that <span class="hlt">aerosol</span> forcing is higher in summer than in winter, and has identified the importance of <span class="hlt">aerosol</span> above cloud in determining black carbon forcing. We show that predicted cloud height is a very important factor in determining normalized radiative forcing (forcing per mass), especially in summer. This can affect the average summer radiative forcing by nearly 50%. Removal by cloud droplets is the dominant atmospheric cleansing mechanism for carbonaceous <span class="hlt">aerosols</span>. We demonstrate the modeled seasonality of removal processes and compare the importance of scavenging by warm and cold clouds. Both types of clouds contribute significantly to <span class="hlt">aerosol</span> removal. We estimate uncertainty in direct radiative forcing due to scavenging by tagging the <span class="hlt">aerosol</span> which has experienced cloud interactions. Finally, seasonal variations offer an opportunity to assess modeled processes when a single process dominates variability. We identify regions where <span class="hlt">aerosol</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140005810','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140005810"><span>Concentration Effects and Ion Properties Controlling the Fractionation of Halides during <span class="hlt">Aerosol</span> Formation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Guzman, Marcelo I.; Athalye, Richa R.; Rodriguez, Jose M.</p> <p>2012-01-01</p> <p>During the <span class="hlt">aerosolization</span> process at the sea surface, halides are incorporated into <span class="hlt">aerosol</span> droplets, where they may play an important role in tropospheric ozone chemistry. Although this process may significantly contribute to the formation of reactive gas phase molecular halogens, little is known about the environmental factors that control how halides selectively accumulate at the air-water interface. In this study, the production of sea spray <span class="hlt">aerosol</span> is simulated using electrospray ionization (ESI) of 100 nM equimolar solutions of NaCl, NaBr, NaI, NaNO2, NaNO3, NaClO4, and NaIO4. The microdroplets generated are analyzed by mass spectrometry to study the comparative enrichment of anions (f (Isub x-)) and their correlation with ion properties. Although no correlation exists between f (sub x-) and the limiting equivalent ionic conductivity, the correlation coefficient of the linear fit with the size of the anions R(sub x-), dehydration free-energy ?Gdehyd, and polarizability alpha, follows the order: (R(sub x-)(exp -2)) > (R(sub x-)(exp -1)) >(R(sub x-) > delta G(sub dehyd) > alpha. The same pure physical process is observed in H2O and D2O. The factor f (sub x-) does not change with pH (6.8-8.6), counterion (Li+, Na+, K+, and Cs+) <span class="hlt">substitution</span> effects, or solvent polarity changes in methanol - and ethanol-water mixtures (0 <= xH2O <= 1). Sodium polysorbate 20 surfactant is used to modify the structure of the interface. Despite the observed enrichment of I- on the air-water interface of equimolar solutions, our results of seawater mimic samples agree with a model in which the interfacial composition is increasingly enriched in I- < Br- < Cl- over the oceanic boundary layer due to concentration effects in sea spray <span class="hlt">aerosol</span> formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29755508','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29755508"><span>Spatiotemporal variability and contribution of different <span class="hlt">aerosol</span> types to the <span class="hlt">Aerosol</span> Optical Depth over the Eastern Mediterranean.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Georgoulias, Aristeidis K; Alexandri, Georgia; Kourtidis, Konstantinos A; Lelieveld, Jos; Zanis, Prodromos; Pöschl, Ulrich; Levy, Robert; Amiridis, Vassilis; Marinou, Eleni; Tsikerdekis, Athanasios</p> <p>2016-01-01</p> <p>This study characterizes the spatiotemporal variability and relative contribution of different types of <span class="hlt">aerosols</span> to the <span class="hlt">Aerosol</span> Optical Depth (AOD) over the Eastern Mediterranean as derived from MODIS Terra (3/2000-12/2012) and Aqua (7/2002-12/2012) satellite instruments. For this purpose, a 0.1° × 0.1° gridded MODIS dataset was compiled and validated against sunphotometric observations from the <span class="hlt">AErosol</span> RObotic NETwork (AERONET). The high spatial resolution and long temporal coverage of the dataset allows for the determination of local hot spots like megacities, medium sized cities, industrial zones, and power plant complexes, seasonal variabilities, and decadal averages. The average AOD at 550 nm (AOD 550 ) for the entire region is ~ 0.22 ± 0.19 with maximum values in summer and seasonal variabilities that can be attributed to precipitation, photochemical production of secondary organic <span class="hlt">aerosols</span>, transport of pollution and smoke from biomass burning in Central and Eastern Europe, and transport of dust from the Sahara Desert and the Middle East. The MODIS data were analyzed together with data from other satellite sensors, reanalysis projects and a chemistry-<span class="hlt">aerosol</span>-transport model using an optimized algorithm tailored for the region and capable of estimating the contribution of different <span class="hlt">aerosol</span> types to the total AOD 550 . The spatial and temporal variability of anthropogenic, dust and fine mode natural <span class="hlt">aerosols</span> over land and anthropogenic, dust and marine <span class="hlt">aerosols</span> over the sea is examined. The relative contribution of the different <span class="hlt">aerosol</span> types to the total AOD 550 exhibits a low/high seasonal variability over land/sea areas, respectively. Overall, anthropogenic <span class="hlt">aerosols</span>, dust and fine mode natural <span class="hlt">aerosols</span> account for ~ 51 %, ~ 34 % and ~ 15 % of the total AOD 550 over land, while, anthropogenic <span class="hlt">aerosols</span>, dust and marine <span class="hlt">aerosols</span> account ~ 40 %, ~ 34 % and ~ 26 % of the total AOD 550 over the sea, based on MODIS Terra and Aqua observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160014678','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160014678"><span>Direct <span class="hlt">Aerosol</span> Radiative Forcing Based on Combined A-Train Observations: Towards All-sky Estimates and Attribution to <span class="hlt">Aerosol</span> Type</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Redemann, Jens; Shinozuka, Y.; Kacenelenbogen, M.; Russell, P.; Vaughan, M.; Ferrare, R.; Hostetler, C.; Rogers, R.; Burton, S.; Livingston, J.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20160014678'); toggleEditAbsImage('author_20160014678_show'); toggleEditAbsImage('author_20160014678_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20160014678_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20160014678_hide"></p> <p>2014-01-01</p> <p>We describe a technique for combining CALIOP <span class="hlt">aerosol</span> backscatter, MODIS spectral AOD (<span class="hlt">aerosol</span> optical depth), and OMI AAOD (absorption <span class="hlt">aerosol</span> optical depth) measurements for the purpose of estimating full spectral sets of <span class="hlt">aerosol</span> radiative properties, and ultimately for calculating the 3-D distribution of direct <span class="hlt">aerosol</span> radiative forcing. We present results using one year of data collected in 2007 and show comparisons of the <span class="hlt">aerosol</span> radiative property estimates to collocated AERONET retrievals. Initial calculations of seasonal clear-sky <span class="hlt">aerosol</span> radiative forcing based on our multi-sensor <span class="hlt">aerosol</span> retrievals compare well with over-ocean and top of the atmosphere IPCC-2007 model-based results, and with more recent assessments in the "Climate Change Science Program Report: Atmospheric <span class="hlt">Aerosol</span> Properties and Climate Impacts" (2009). We discuss some of the challenges that exist in extending our clear-sky results to all-sky conditions. On the basis of comparisons to suborbital measurements, we present some of the limitations of the MODIS and CALIOP retrievals in the presence of adjacent or underlying clouds. Strategies for meeting these challenges are discussed. We also discuss a methodology for using the multi-sensor <span class="hlt">aerosol</span> retrievals for <span class="hlt">aerosol</span> type classification based on advanced clustering techniques. The combination of research results permits conclusions regarding the attribution of <span class="hlt">aerosol</span> radiative forcing to <span class="hlt">aerosol</span> type.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4529366','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4529366"><span>Production of Highly Charged Pharmaceutical <span class="hlt">Aerosols</span> Using a New <span class="hlt">Aerosol</span> Induction Charger</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Golshahi, Laleh; Longest, P. Worth; Holbrook, Landon; Snead, Jessica; Hindle, Michael</p> <p>2015-01-01</p> <p>Purpose Properly charged particles can be used for effective lung targeting of pharmaceutical <span class="hlt">aerosols</span>. The objective of this study was to characterize the performance of a new induction charger that operates with a mesh nebulizer for the production of highly charged submicrometer <span class="hlt">aerosols</span> to bypass the mouth-throat and deliver clinically relevant doses of medications to the lungs. Methods Variables of interest included combinations of model drug (i.e. albuterol sulfate) and charging excipient (NaCl) as well as strength of the charging field (1–5 kV/cm). <span class="hlt">Aerosol</span> charge and size were measured using a modified electrical low pressure impactor system combined with high performance liquid chromatography. Results At the approximate mass median aerodynamic diameter (MMAD) of the <span class="hlt">aerosol</span> (~ 0.4 μm), the induction charge on the particles was an order of magnitude above the field and diffusion charge limit. The nebulization rate was 439.3 ± 42.9 μl/min, which with a 0.1 % w/v solution delivered 419.5 ± 34.2 μg of medication per minute. A new correlation was developed to predict particle charge produced by the induction charger. Conclusions The combination of the <span class="hlt">aerosol</span> induction charger and predictive correlations will allow for the practical generation and control of charged submicrometer <span class="hlt">aerosols</span> for targeting deposition within the lungs. PMID:25823649</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.U21B..01B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.U21B..01B"><span>Importance of Anthropogenic <span class="hlt">Aerosols</span> for Climate Prediction: a Study on East Asian Sulfate <span class="hlt">Aerosols</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bartlett, R. E.; Bollasina, M. A.</p> <p>2017-12-01</p> <p>Climate prediction is vital to ensure that we are able to adapt to our changing climate. Understandably, the main focus for such prediction is greenhouse gas forcing, as this will be the main anthropogenic driver of long-term global climate change; however, other forcings could still be important. Atmospheric <span class="hlt">aerosols</span> represent one such forcing, especially in regions with high present-day <span class="hlt">aerosol</span> loading such as Asia; yet, uncertainty in their future emissions are under-sampled by commonly used climate forcing projections, such as the Representative Concentration Pathways (RCPs). Globally, anthropogenic <span class="hlt">aerosols</span> exert a net cooling, but their effects show large variation at regional scales. Studies have shown that <span class="hlt">aerosols</span> impact locally upon temperature, precipitation and hydroclimate, and also upon larger scale atmospheric circulation (for example, the Asian monsoon) with implications for climate remote from <span class="hlt">aerosol</span> sources. We investigate how future climate could evolve differently given the same greenhouse gas forcing pathway but differing <span class="hlt">aerosol</span> emissions. Specifically, we use climate modelling experiments (using HadGEM2-ES) of two scenarios based upon RCP2.6 greenhouse gas forcing but with large differences in sulfur dioxide emissions over East Asia. Results show that increased sulfate <span class="hlt">aerosols</span> (associated with increased sulfur dioxide) lead to large regional cooling through <span class="hlt">aerosol</span>-radiation and <span class="hlt">aerosol</span>-cloud interactions. Focussing on dynamical mechanisms, we explore the consequences of this cooling for the Asian summer and winter monsoons. In addition to local temperature and precipitation changes, we find significant changes to large scale atmospheric circulation. Wave-like responses to upper-level atmospheric changes propagate across the northern hemisphere with far-reaching effects on surface climate, for example, cooling over Europe. Within the tropics, we find alterations to zonal circulation (notably, shifts in the Pacific Walker cell) and monsoon</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1089860','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1089860"><span>Geometrical Optics of Dense <span class="hlt">Aerosols</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Hay, Michael J.; Valeo, Ernest J.; Fisch, Nathaniel J.</p> <p>2013-04-24</p> <p>Assembling a free-standing, sharp-edged slab of homogeneous material that is much denser than gas, but much more rare ed than a solid, is an outstanding technological challenge. The solution may lie in focusing a dense <span class="hlt">aerosol</span> to assume this geometry. However, whereas the geometrical optics of dilute <span class="hlt">aerosols</span> is a well-developed fi eld, the dense <span class="hlt">aerosol</span> limit is mostly unexplored. Yet controlling the geometrical optics of dense <span class="hlt">aerosols</span> is necessary in preparing such a material slab. Focusing dense <span class="hlt">aerosols</span> is shown here to be possible, but the nite particle density reduces the eff ective Stokes number of the flow, amore » critical result for controlled focusing. __________________________________________________« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EOSTr..91....3K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EOSTr..91....3K"><span><span class="hlt">Aerosol</span> Remote Sensing From Space</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kokhanovsky, A.; Kinne, S.</p> <p>2010-01-01</p> <p>Determination of Atmospheric <span class="hlt">Aerosol</span> Properties Using Satellite Measurements;Bad Honnef, Germany, 16-19 August 2009; <span class="hlt">Aerosol</span> optical depth (AOD), a measure of how much light is attenuated by <span class="hlt">aerosol</span> particles, provides scientists information about the amount and type of <span class="hlt">aerosols</span> in the atmosphere. Recent developments in <span class="hlt">aerosol</span> remote sensing was the theme of a workshop held in Germany. The workshop was sponsored by the Wilhelm and Else Heraeus Foundation and attracted 67 participants from 12 countries. The workshop focused on the determination (retrieval) of AOD and its spectral dependence using measurements of changes to the solar radiation back-scattered to space. The midvisible AOD is usually applied to define <span class="hlt">aerosol</span> amount, while the size of <span class="hlt">aerosol</span> particles is indicated by the AOD spectral dependence and is commonly expressed by the Angstrom parameter. Identical properties retrieved by different sensors, however, display significant diversity, especially over continents. A major reason for this is that the derivation of AOD requires more accurate determination of nonaerosol contributions to the sensed satellite signal than is usually available. In particular, surface reflectance data as a function of the viewing geometry and robust cloud-clearing methods are essential retrieval elements. In addition, the often needed assumptions about <span class="hlt">aerosol</span> properties in terms of absorption and size are more reasons for the discrepancy between different AOD measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010087128&hterms=Russell&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26Nf%3DPublication-Date%257CBTWN%2B20000101%2B20001231%26N%3D0%26No%3D20%26Ntt%3DRussell','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010087128&hterms=Russell&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26Nf%3DPublication-Date%257CBTWN%2B20000101%2B20001231%26N%3D0%26No%3D20%26Ntt%3DRussell"><span>On the Feasibility of Studying Shortwave <span class="hlt">Aerosol</span> Radiative Forcing of Climate Using Dual-Wavelength <span class="hlt">Aerosol</span> Backscatter Lidar</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Redemann, Jens; Russell, Philip B.; Winker, David M.; McCormick, M. Patrick; Hipskind, R. Stephen (Technical Monitor)</p> <p>2000-01-01</p> <p>The current low confidence in the estimates of <span class="hlt">aerosol</span>-induced perturbations of Earth's radiation balance is caused by the highly non-uniform compositional, spatial and temporal distributions of tropospheric <span class="hlt">aerosols</span> on a global scale owing to their heterogeneous sources and short lifetimes. Nevertheless, recent studies have shown that the inclusion of <span class="hlt">aerosol</span> effects in climate model calculations can improve agreement with observed spatial and temporal temperature distributions. In light of the short lifetimes of <span class="hlt">aerosols</span>, determination of their global distribution with space-borne sensors seems to be a necessary approach. Until recently, satellite measurements of tropospheric <span class="hlt">aerosols</span> have been approximate and did not provide the full set of information required to determine their radiative effects. With the advent of active <span class="hlt">aerosol</span> remote sensing from space (e.g., PICASSO-CENA), the applicability fo lidar-derived <span class="hlt">aerosol</span> 180 deg -backscatter data to radiative flux calculations and hence studies of <span class="hlt">aerosol</span> effects on climate needs to be investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ERL.....7c1001P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ERL.....7c1001P"><span>Small volcanic eruptions and the stratospheric sulfate <span class="hlt">aerosol</span> burden</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pyle, David M.</p> <p>2012-09-01</p> <p> (Rampino and Self 1984, Pyle et al 1996, Self and Rampino 2012). But as yet, there is little evidence for the consequences of this scale of eruption for the climate system (Miles et al 2004), and few data against which to test simulations of stratospheric sulfur-injection '<span class="hlt">geoengineering</span>' scenarios of a similar scale and frequency (e.g. English et al 2012). A hint of the new volcano-observing capability came during the eruption of Eyjafjallajökull, Iceland. For a few days in April 2010 meteorological conditions, coupled with a dramatic increase in volcanic ash production, led to the wide dispersal of fine volcanic particles across northern Europe; an event which was widely tracked by ground-based and satellite-borne instruments, augmented by in situ measurements from balloons and aircraft (Bennett et al 2010, Flentje et al 2010, Harrison et al 2010, Stohl et al 2011). Despite the interest in Eyjafjallajökull at the time, this was, geologically, only a very modest eruption with limited sulfur emissions and an impact restricted mainly to the regional troposphere (e.g. Thomas and Prata 2011, Walker et al 2012). Then, in June 2011, a previously dormant volcano in north-east Africa began to erupt violently. Little is known about Nabro, which is a partially collapsed volcano that straddles the Eritrea-Ethiopia border, and has had no known historical activity (Wiart and Oppenheimer 2005). Despite the remote location, and lack of prior warning, the event and its aftermath were remarkably well captured by remote-sensing instruments, as demonstrated in the new letter by Sawamura et al (2012). Using both ground-based and satellite-borne laser-ranging (lidar) data, Sawamura et al (2012) were able to extract detailed information about the nature of the volcanic <span class="hlt">aerosol</span> layer, and its spread around the globe. The eruption started strongly, with substantial ash plumes for the first 48 h, rising to 9-14 km altitude (Smithsonian Institution 2011, Bourassa et al 2012), that carried at</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110023005&hterms=EFFECTS+BLACK+CARBON&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DEFFECTS%2BOF%2BBLACK%2BCARBON','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110023005&hterms=EFFECTS+BLACK+CARBON&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DEFFECTS%2BOF%2BBLACK%2BCARBON"><span>Cloud Cover Increase with Increasing <span class="hlt">Aerosol</span> Absorptivity: A Counterexample to the Conventional Semidirect <span class="hlt">Aerosol</span> Effect</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Perlwitz, Jan; Miller, Ron L.</p> <p>2010-01-01</p> <p>We reexamine the <span class="hlt">aerosol</span> semidirect effect using a general circulation model and four cases of the single-scattering albedo of dust <span class="hlt">aerosols</span>. Contrary to the expected decrease in low cloud cover due to heating by tropospheric <span class="hlt">aerosols</span>, we find a significant increase with increasing absorptivity of soil dust particles in regions with high dust load, except during Northern Hemisphere winter. The strongest sensitivity of cloud cover to dust absorption is found over land during Northern Hemisphere summer. Here even medium and high cloud cover increase where the dust load is highest. The cloud cover change is directly linked to the change in relative humidity in the troposphere as a result of contrasting changes in specific humidity and temperature. More absorption by <span class="hlt">aerosols</span> leads to larger diabatic heating and increased warming of the column, decreasing relative humidity. However, a corresponding increase in the specific humidity exceeds the temperature effect on relative humidity. The net effect is more low cloud cover with increasing <span class="hlt">aerosol</span> absorption. The higher specific humidity where cloud cover strongly increases is attributed to an enhanced convergence of moisture driven by dust radiative heating. Although in some areas our model exhibits a reduction of low cloud cover due to <span class="hlt">aerosol</span> heating consistent with the conventional description of the semidirect effect, we conclude that the link between <span class="hlt">aerosols</span> and clouds is more varied, depending also on changes in the atmospheric circulation and the specific humidity induced by the <span class="hlt">aerosols</span>. Other absorbing <span class="hlt">aerosols</span> such as black carbon are expected to have a similar effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1012285-indirect-semi-direct-aerosol-campaign-impact-arctic-aerosols-clouds','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1012285-indirect-semi-direct-aerosol-campaign-impact-arctic-aerosols-clouds"><span>Indirect and Semi-Direct <span class="hlt">Aerosol</span> Campaign: The Impact of Arctic <span class="hlt">Aerosols</span> on Clouds</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>McFarquhar, Greg; Ghan, Steven J.; Verlinde, J.</p> <p>2011-02-01</p> <p>A comprehensive dataset of microphysical and radiative properties of <span class="hlt">aerosols</span> and clouds in the arctic boundary layer in the vicinity of Barrow, Alaska was collected in April 2008 during the Indirect and Semi-Direct <span class="hlt">Aerosol</span> Campaign (ISDAC) sponsored by the Department of Energy Atmospheric Radiation Measurement (ARM) and Atmospheric Science Programs. The primary aim of ISDAC was to examine indirect effects of <span class="hlt">aerosols</span> on clouds that contain both liquid and ice water. The experiment utilized the ARM permanent observational facilities at the North Slope of Alaska (NSA) in Barrow. These include a cloud radar, a polarized micropulse lidar, and an atmosphericmore » emitted radiance interferometer as well as instruments specially deployed for ISDAC measuring <span class="hlt">aerosol</span>, ice fog, precipitation and spectral shortwave radiation. The National Research Council of Canada Convair-580 flew 27 sorties during ISDAC, collecting data using an unprecedented 42 cloud and <span class="hlt">aerosol</span> instruments for more than 100 hours on 12 different days. Data were obtained above, below and within single-layer stratus on 8 April and 26 April 2008. These data enable a process-oriented understanding of how <span class="hlt">aerosols</span> affect the microphysical and radiative properties of arctic clouds influenced by different surface conditions. Observations acquired on a heavily polluted day, 19 April 2008, are enhancing this understanding. Data acquired in cirrus on transit flights between Fairbanks and Barrow are improving our understanding of the performance of cloud probes in ice. Ultimately the ISDAC data will be used to improve the representation of cloud and <span class="hlt">aerosol</span> processes in models covering a variety of spatial and temporal scales, and to determine the extent to which long-term surface-based measurements can provide retrievals of <span class="hlt">aerosols</span>, clouds, precipitation and radiative heating in the Arctic.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A43N..06N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A43N..06N"><span>Reconciling the <span class="hlt">aerosol</span>-liquid water path relationship in the ECHAM6-HAM GCM and the <span class="hlt">Aerosol</span>_cci/Cloud_cci (A)ATSR dataset by minimizing the effect of <span class="hlt">aerosol</span> swelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neubauer, D.; Christensen, M.; Lohmann, U.; Poulsen, C. A.</p> <p>2016-12-01</p> <p>Studies using present day variability to assess statistical relationships between <span class="hlt">aerosol</span> and cloud properties find different strengths of these relationships between satellite data and general circulation model (GCM) data. This discrepancy can be explained by structural uncertainties due to differences in the analysis/observational scale and the process scale or spurious relationships between <span class="hlt">aerosol</span> and cloud properties. Such spurious relationships are the growth of <span class="hlt">aerosol</span> particles in the humid environment surrounding clouds, misclassification of partly cloudy satellite pixels as cloud free pixels, brightening of <span class="hlt">aerosol</span> particles by sunlight reflected at cloud edges, or effects of clouds on <span class="hlt">aerosol</span> like processing of <span class="hlt">aerosol</span> particles in clouds by nucleation or impact scavenging and subsequent growth by heterogeneous chemistry and release by cloud droplet evaporation or wet scavenging of <span class="hlt">aerosol</span> particles. To minimize the effects of spatial aggregation and spurious relationships we apply a new nearest neighbour approach to high resolution (A)ATSR datasets from the <span class="hlt">Aerosol</span>_cci and Cloud_cci projects of the Climate Change Initiative (CCI) programme of ESA. For the ECHAM6-HAM GCM we quantify the impact of using dry <span class="hlt">aerosol</span> (without <span class="hlt">aerosol</span> water) in the analysis to mimic the effect of the nearest neighbour approach. The <span class="hlt">aerosol</span>-liquid water path relationship in ECHAM6-HAM is systematically stronger than in (A)ATSR data and cannot be explained by an overestimation of autoconversion when using diagnostic precipitation but rather by <span class="hlt">aerosol</span> swelling in regions where humidity is high and clouds are present. When <span class="hlt">aerosol</span> water is removed from the analysis in ECHAM6-HAM the strength of the <span class="hlt">aerosol</span>-liquid water path relationship agrees much better with the ones of (A)ATSR or MODIS. We further find that while the observed relationships of different satellite sensors ((A)ATSR vs. MODIS) are not always consistent for tested environmental conditions the relationships in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170005837','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170005837"><span>Relationship Between <span class="hlt">Aerosol</span> Optical Depth and Particulate Matter Over Singapore: Effects of <span class="hlt">Aerosol</span> Vertical Distributions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chew, Boo Ning; Campbell, James; Hyer, Edward J.; Salinas, Santo V.; Reid, Jeffrey S.; Welton, Ellsworth J.; Holben, Brent N.; Liew, Soo Chin</p> <p>2016-01-01</p> <p>As part of the Seven Southeast Asian Studies (7SEAS) program, an <span class="hlt">Aerosol</span> Robotic Network (AERONET) sun photometer and a Micro-Pulse Lidar Network (MPLNET) instrument have been deployed at Singapore to study the regional <span class="hlt">aerosol</span> environment of the Maritime Continent (MC). In addition, the Navy <span class="hlt">Aerosol</span> Analysis and Prediction System (NAAPS) is used to model <span class="hlt">aerosol</span> transport over the region. From 24 September 2009 to 31 March 2011, the relationships between ground-, satellite- and model-based <span class="hlt">aerosol</span> optical depth (AOD) and particulate matter with aerodynamic equivalent diameters less than 2.5 microns (PM2.5) for air quality applications are investigated. When MPLNET-derived <span class="hlt">aerosol</span> scale heights are applied to normalize AOD for comparison with surface PM2.5 data, the empirical relationships are shown to improve with an increased 11%, 10% and 5% in explained variances, for AERONET, MODIS and NAAPS respectively. The ratios of root mean square errors to standard deviations for the relationships also show corresponding improvements of 8%, 6% and 2%. <span class="hlt">Aerosol</span> scale heights are observed to be bimodal with a mode below and another above the strongly-capped/deep near-surface layer (SCD; 0-1.35 km). <span class="hlt">Aerosol</span> extinctions within the SCD layer are well-correlated with surface PM2.5 concentrations, possibly due to strong vertical mixing in the region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3390382','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3390382"><span>Effect of Dust and Anthropogenic <span class="hlt">Aerosols</span> on Columnar <span class="hlt">Aerosol</span> Optical Properties over Darjeeling (2200 m asl), Eastern Himalayas, India</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chatterjee, Abhijit; Ghosh, Sanjay K.; Adak, Anandamay; Singh, Ajay K.; Devara, Panuganti C. S.; Raha, Sibaji</p> <p>2012-01-01</p> <p>Background The loading of atmospheric particulate matter (<span class="hlt">aerosol</span>) in the eastern Himalaya is mainly regulated by the locally generated anthropogenic <span class="hlt">aerosols</span> from the biomass burning and by the <span class="hlt">aerosols</span> transported from the distance sources. These different types of <span class="hlt">aerosol</span> loading not only affect the <span class="hlt">aerosol</span> chemistry but also produce consequent signature on the radiative properties of <span class="hlt">aerosol</span>. Methodology/Principal Findings An extensive study has been made to study the seasonal variations in <span class="hlt">aerosol</span> components of fine and coarse mode <span class="hlt">aerosols</span> and black carbon along with the simultaneous measurements of <span class="hlt">aerosol</span> optical depth on clear sky days over Darjeeling, a high altitude station (2200 masl) at eastern Himalayas during the year 2008. We observed a heavy loading of fine mode dust component (Ca2+) during pre-monsoon (Apr – May) which was higher by 162% than its annual mean whereas during winter (Dec – Feb), the loading of anthropogenic <span class="hlt">aerosol</span> components mainly from biomass burning (fine mode SO4 2− and black carbon) were higher (76% for black carbon and 96% for fine mode SO4 2−) from their annual means. These high increases in dust <span class="hlt">aerosols</span> during pre-monsoon and anthropogenic <span class="hlt">aerosols</span> during winter enhanced the <span class="hlt">aerosol</span> optical depth by 25 and 40%, respectively. We observed that for every 1% increase in anthropogenic <span class="hlt">aerosols</span>, AOD increased by 0.55% during winter whereas for every 1% increase in dust <span class="hlt">aerosols</span>, AOD increased by 0.46% during pre-monsoon. Conclusion/Significance The natural dust transport process (during pre-monsoon) plays as important a role in the radiation effects as the anthropogenic biomass burning (during winter) and their differential effects (rate of increase of the AOD with that of the <span class="hlt">aerosol</span> concentration) are also very similar. This should be taken into account in proper modeling of the atmospheric environment over eastern Himalayas. PMID:22792264</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22792264','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22792264"><span>Effect of dust and anthropogenic <span class="hlt">aerosols</span> on columnar <span class="hlt">aerosol</span> optical properties over Darjeeling (2200 m asl), eastern Himalayas, India.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chatterjee, Abhijit; Ghosh, Sanjay K; Adak, Anandamay; Singh, Ajay K; Devara, Panuganti C S; Raha, Sibaji</p> <p>2012-01-01</p> <p>The loading of atmospheric particulate matter (<span class="hlt">aerosol</span>) in the eastern Himalaya is mainly regulated by the locally generated anthropogenic <span class="hlt">aerosols</span> from the biomass burning and by the <span class="hlt">aerosols</span> transported from the distance sources. These different types of <span class="hlt">aerosol</span> loading not only affect the <span class="hlt">aerosol</span> chemistry but also produce consequent signature on the radiative properties of <span class="hlt">aerosol</span>. An extensive study has been made to study the seasonal variations in <span class="hlt">aerosol</span> components of fine and coarse mode <span class="hlt">aerosols</span> and black carbon along with the simultaneous measurements of <span class="hlt">aerosol</span> optical depth on clear sky days over Darjeeling, a high altitude station (2200 masl) at eastern Himalayas during the year 2008. We observed a heavy loading of fine mode dust component (Ca(2+)) during pre-monsoon (Apr-May) which was higher by 162% than its annual mean whereas during winter (Dec-Feb), the loading of anthropogenic <span class="hlt">aerosol</span> components mainly from biomass burning (fine mode SO(4)(2-) and black carbon) were higher (76% for black carbon and 96% for fine mode SO(4)(2-)) from their annual means. These high increases in dust <span class="hlt">aerosols</span> during pre-monsoon and anthropogenic <span class="hlt">aerosols</span> during winter enhanced the <span class="hlt">aerosol</span> optical depth by 25 and 40%, respectively. We observed that for every 1% increase in anthropogenic <span class="hlt">aerosols</span>, AOD increased by 0.55% during winter whereas for every 1% increase in dust <span class="hlt">aerosols</span>, AOD increased by 0.46% during pre-monsoon. The natural dust transport process (during pre-monsoon) plays as important a role in the radiation effects as the anthropogenic biomass burning (during winter) and their differential effects (rate of increase of the AOD with that of the <span class="hlt">aerosol</span> concentration) are also very similar. This should be taken into account in proper modeling of the atmospheric environment over eastern Himalayas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A13F2162L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A13F2162L"><span>The physico-chemical evolution of atmospheric <span class="hlt">aerosols</span> and the gas-particle partitioning of inorganic <span class="hlt">aerosol</span> during KORUS-AQ</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, T.; Park, T.; Lee, J. B.; Lim, Y. J.; Ahn, J.; Park, J. S.; Soo, C. J.; Desyaterik, Y.; Collett, J. L., Jr.</p> <p>2017-12-01</p> <p><span class="hlt">Aerosols</span> influence climate change directly by scattering and absorption and indirectly by acting as cloud condensation nuclei and some of the effects of <span class="hlt">aerosols</span> are reduction in visibility, deterioration of human health, and deposition of pollutants to ecosystems. Urban area is large source of <span class="hlt">aerosols</span> and <span class="hlt">aerosol</span> precursors. <span class="hlt">Aerosol</span> sources are both local and from long-range transport. Long-range transport processed <span class="hlt">aerosol</span> are often dominant sources of <span class="hlt">aerosol</span> pollution in Korea. To improve our knowledge of <span class="hlt">aerosol</span> chemistry, Korea and U.S-Air Quality (KORUS-AQ) of Aircraft-based <span class="hlt">aerosol</span> measurement took place in and around Seoul, Korea during May and June 2016. KORUS-AQ campaigns were conducted to study the chemical characterization and processes of pollutants in the Seoul Metropolitan area to regional scales of Korean peninsula. Aerodyne High Resolution Time of Flight <span class="hlt">Aerosol</span> Mass Spectrometer (HR-ToF-AMS) was deployed on aircraft platforms on-board DC-8 (NASA) aircraft. We characterized <span class="hlt">aerosol</span> chemical properties and mass concentrations of sulfate, nitrate, ammonium and organics in polluted air plumes and investigate the spatial and vertical distribution of the species. The results of studies show that organics is predominant in <span class="hlt">Aerosol</span> and a significant fraction of the organics is oxygenated organic <span class="hlt">aerosol</span> (OOA) at the high altitude. Both Nitrate and sulfate can partition between the gas and particle phases. The ratios for HNO3/(N(V) (=gaseous HNO3 + particulate Nitrate) and SO2/(SO2+Sulfate) were found to exhibit quite different distributions between the particles and gas phase for the locations during KORUS-AQ campaign, representing potential for formation of additional particulate nitrate and sulfate. The results of those studies can provide highly resolved temporal and spatial air pollutant, which are valuable for air quality model input parameters for <span class="hlt">aerosol</span> behaviour.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.6560T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.6560T"><span>Easy Volcanic <span class="hlt">Aerosol</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Toohey, Matthew; Stevens, Bjorn; Schmidt, Hauke; Timmreck, Claudia</p> <p>2016-04-01</p> <p>Radiative forcing by stratospheric sulfate <span class="hlt">aerosol</span> of volcanic origin is one of the strongest drivers of natural climate variability. Transient model simulations attempting to match observed climate variability, such as the CMIP historical simulations, rely on volcanic forcing reconstructions based on observations of a small sample of recent eruptions and coarse proxy data for eruptions before the satellite era. Volcanic forcing data sets used in CMIP5 were provided either in terms of optical properties, or in terms of sulfate <span class="hlt">aerosol</span> mass, leading to significant inter-model spread in the actual volcanic radiative forcing produced by models and in their resulting climate responses. It remains therefore unclear to what degree inter-model spread in response to volcanic forcing represents model differences or variations in the forcing. In order to isolate model differences, Easy Volcanic <span class="hlt">Aerosol</span> (EVA) provides an analytic representation of volcanic stratospheric <span class="hlt">aerosol</span> forcing, based on available observations and <span class="hlt">aerosol</span> model results, prescribing the <span class="hlt">aerosol</span>'s radiative properties and primary modes of spatial and temporal variability. In contrast to regriddings of observational data, EVA allows for the production of physically consistent forcing for historic and hypothetical eruptions of varying magnitude, source latitude, and season. Within CMIP6, EVA will be used to reconstruct volcanic forcing over the past 2000 years for use in the Paleo-Modeling Intercomparison Project (PMIP), and will provide forcing sets for VolMIP experiments aiming to quantify model uncertainty in the response to volcanic forcing. Here, the functional form of EVA will be introduced, along with illustrative examples including the EVA-based reconstruction of volcanic forcing over the historical period, and that of the 1815 Tambora eruption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.6238W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.6238W"><span>Development the EarthCARE <span class="hlt">aerosol</span> classification scheme</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wandinger, Ulla; Baars, Holger; Hünerbein, Anja; Donovan, Dave; van Zadelhoff, Gerd-Jan; Fischer, Jürgen; von Bismarck, Jonas; Eisinger, Michael; Lajas, Dulce; Wehr, Tobias</p> <p>2015-04-01</p> <p>The Earth Clouds, <span class="hlt">Aerosols</span> and Radiation Explorer (EarthCARE) mission is a joint ESA/JAXA mission planned to be launched in 2018. The multi-sensor platform carries a cloud-profiling radar (CPR), a high-spectral-resolution cloud/<span class="hlt">aerosol</span> lidar (ATLID), a cloud/<span class="hlt">aerosol</span> multi-spectral imager (MSI), and a three-view broad-band radiometer (BBR). Three out of the four instruments (ATLID, MSI, and BBR) will be able to sense the global <span class="hlt">aerosol</span> distribution and contribute to the overarching EarthCARE goals of sensor synergy and radiation closure with respect to <span class="hlt">aerosols</span>. The high-spectral-resolution lidar ATLID obtains profiles of particle extinction and backscatter coefficients, lidar ratio, and linear depolarization ratio as well as the <span class="hlt">aerosol</span> optical thickness (AOT) at 355 nm. MSI provides AOT at 670 nm (over land and ocean) and 865 nm (over ocean). Next to these primary observables the <span class="hlt">aerosol</span> type is one of the required products to be derived from both lidar stand-alone and ATLID-MSI synergistic retrievals. ATLID measurements of the <span class="hlt">aerosol</span> intensive properties (lidar ratio, depolarization ratio) and ATLID-MSI observations of the spectral AOT will provide the basic input for <span class="hlt">aerosol</span>-type determination. <span class="hlt">Aerosol</span> typing is needed for the quantification of anthropogenic versus natural <span class="hlt">aerosol</span> loadings of the atmosphere, the investigation of <span class="hlt">aerosol</span>-cloud interaction, assimilation purposes, and the validation of atmospheric transport models which carry components like dust, sea salt, smoke and pollution. Furthermore, <span class="hlt">aerosol</span> classification is a prerequisite for the estimation of direct <span class="hlt">aerosol</span> radiative forcing and radiative closure studies. With an appropriate underlying microphysical particle description, the categorization of <span class="hlt">aerosol</span> observations into predefined <span class="hlt">aerosol</span> types allows us to infer information needed for the calculation of shortwave radiative effects, such as mean particle size, single-scattering albedo, and spectral conversion factors. In order to ensure</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020081319&hterms=usher&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dusher','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020081319&hterms=usher&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dusher"><span>Global <span class="hlt">Aerosol</span> Remote Sensing from MODIS</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ichoku, Charles; Kaufman, Yoram J.; Remer, Lorraine A.; Chu, D. Allen; Mattoo, Shana; Tanre, Didier; Levy, Robert; Li, Rong-Rong; Martins, Jose V.; Lau, William K. M. (Technical Monitor)</p> <p>2002-01-01</p> <p>The physical characteristics, composition, abundance, spatial distribution and dynamics of global <span class="hlt">aerosols</span> are still very poorly known, and new data from satellite sensors have long been awaited to improve current understanding and to give a boost to the effort in future climate predictions. The derivation of <span class="hlt">aerosol</span> parameters from the MODerate resolution Imaging Spectro-radiometer (MODIS) sensors aboard the Earth Observing System (EOS) Terra and Aqua polar-orbiting satellites ushers in a new era in <span class="hlt">aerosol</span> remote sensing from space. Terra and Aqua were launched on December 18, 1999 and May 4, 2002 respectively, with daytime equator crossing times of approximately 10:30 am and 1:30 pm respectively. Several <span class="hlt">aerosol</span> parameters are retrieved at 10-km spatial resolution (level 2) from MODIS daytime data. The MODIS <span class="hlt">aerosol</span> algorithm employs different approaches to retrieve parameters over land and ocean surfaces, because of the inherent differences in the solar spectral radiance interaction with these surfaces. The parameters retrieved include: <span class="hlt">aerosol</span> optical thickness (AOT) at 0.47, 0.55 and 0.66 micron wavelengths over land, and at 0.47, 0.55, 0.66, 0.87, 1.2, 1.6, and 2.1 micron over ocean; Angstrom exponent over land and ocean; and effective radii, and the proportion of AOT contributed by the small mode <span class="hlt">aerosols</span> over ocean. To ensure the quality of these parameters, a substantial part of the Terra-MODIS <span class="hlt">aerosol</span> products were validated globally and regionally, based on cross correlation with corresponding parameters derived from ground-based measurements from AERONET (<span class="hlt">AErosol</span> RObotic NETwork) sun photometers. Similar validation efforts are planned for the Aqua-MODIS <span class="hlt">aerosol</span> products. The MODIS level 2 <span class="hlt">aerosol</span> products are operationally aggregated to generate global daily, eight-day (weekly), and monthly products at one-degree spatial resolution (level 3). MODIS <span class="hlt">aerosol</span> data are used for the detailed study of local, regional, and global <span class="hlt">aerosol</span> concentration</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A42B..08K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A42B..08K"><span>AERONET derived (BC) <span class="hlt">aerosol</span> absorption</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kinne, S.</p> <p>2015-12-01</p> <p>AERONET is a ground-based sun-/sky-photometer network with good annual statistics at more than 400 sites worldwide. Inversion methods applied to these data define all relevant column <span class="hlt">aerosol</span> optical properties and reveal even microphysical detail. The extracted data include estimates for <span class="hlt">aerosol</span> size-distributions and for <span class="hlt">aerosol</span> refractive indices at four different solar wavelengths. Hereby, the imaginary parts of the refractive indices define the <span class="hlt">aerosol</span> column absorption. For regional and global averages and radiative impact assessment with off-line radiative transfer, these local data have been extended with distribution patterns offered by AeroCom modeling experiments. Annual and seasonal absorption distributions for total <span class="hlt">aerosol</span> and estimates for component contributions (such as BC) are presented and associated direct forcing impacts are quantified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.5435H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.5435H"><span>Development and first application of an <span class="hlt">Aerosol</span> Collection Module (ACM) for quasi online compound specific <span class="hlt">aerosol</span> measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hohaus, Thorsten; Kiendler-Scharr, Astrid; Trimborn, Dagmar; Jayne, John; Wahner, Andreas; Worsnop, Doug</p> <p>2010-05-01</p> <p>Atmospheric <span class="hlt">aerosols</span> influence climate and human health on regional and global scales (IPCC, 2007). In many environments organics are a major fraction of the <span class="hlt">aerosol</span> influencing its properties. Due to the huge variety of organic compounds present in atmospheric <span class="hlt">aerosol</span> current measurement techniques are far from providing a full speciation of organic <span class="hlt">aerosol</span> (Hallquist et al., 2009). The development of new techniques for compound specific measurements with high time resolution is a timely issue in organic <span class="hlt">aerosol</span> research. Here we present first laboratory characterisations of an <span class="hlt">aerosol</span> collection module (ACM) which was developed to allow for the sampling and transfer of atmospheric PM1 <span class="hlt">aerosol</span>. The system consists of an aerodynamic lens system focussing particles on a beam. This beam is directed to a 3.4 mm in diameter surface which is cooled to -30 °C with liquid nitrogen. After collection the <span class="hlt">aerosol</span> sample can be evaporated from the surface by heating it to up to 270 °C. The sample is transferred through a 60cm long line with a carrier gas. In order to test the ACM for linearity and sensitivity we combined it with a GC-MS system. The tests were performed with octadecane <span class="hlt">aerosol</span>. The octadecane mass as measured with the ACM-GC-MS was compared versus the mass as calculated from SMPS derived total volume. The data correlate well (R2 0.99, slope of linear fit 1.1) indicating 100 % collection efficiency. From 150 °C to 270 °C no effect of desorption temperature on transfer efficiency could be observed. The ACM-GC-MS system was proven to be linear over the mass range 2-100 ng and has a detection limit of ~ 2 ng. First experiments applying the ACM-GC-MS system were conducted at the Jülich <span class="hlt">Aerosol</span> Chamber. Secondary organic <span class="hlt">aerosol</span> (SOA) was formed from ozonolysis of 600 ppbv of b-pinene. The major oxidation product nopinone was detected in the <span class="hlt">aerosol</span> and could be shown to decrease from 2 % of the total <span class="hlt">aerosol</span> to 0.5 % of the <span class="hlt">aerosol</span> over the 48 hours of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E.628D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E.628D"><span>Assessment of <span class="hlt">aerosol</span> indirect effects over Indian subcontinent using long term MODIS <span class="hlt">aerosol</span> and cloud data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Das, Saurabh; Maitra, Animesh; Saha, Upal; De, Arijit</p> <p></p> <p><span class="hlt">Aerosols</span> have direct consequences on climate research and in climate change study due to its role in radiative forcing. The modulation of cloud properties due to the presence of <span class="hlt">aerosol</span> is another important factor in understanding of the climate change scenario. However, the relationship between these two is mostly indirect as the meteorological conditions have a strong impact on the relationship. Cloud effective radius and decreases in precipitation efficiency are interlinked with the increase of <span class="hlt">aerosols</span>. The net effect is that the cloud liquid water path and cloud lifetime increase with AOD. Though these facts are included in the global climate models (GCM), the quantitative estimation of <span class="hlt">aerosol</span> indirect efficiency (AIE) varied widely. Some recent studies indicate an increasing trend of the <span class="hlt">aerosol</span> optical depth over the Indian landmass. The anthropogenic activities are linked with this increase in <span class="hlt">aerosols</span>. In general, <span class="hlt">aerosol</span> increase can affect the cloud radius and leads to formation of non-precipitating cloud. However, the chemical composition of <span class="hlt">aerosols</span> may also be an important factor. It is therefore necessary to have better understanding of the relationship for predicting the future climate which may be affected by such human activities. In this paper, the relation of <span class="hlt">aerosol</span> optical depth (AOD) with cloud effective radius (CER) has been investigated over the Indian subcontinent using the long term MODIS observations. MODIS can able to provide reliable AOD information over the land surface. It also able to provide information of the cloud effective radius of the same observation point. A grid-wise correlation analysis can thus be performed to estimate the relation between AOD and CER. Result indicates both positive and negative AIE of AOD on CER. To identify the possible reason for such variability in the AIE, the role of anthropogenic <span class="hlt">aerosols</span> and water vapor is investigated. The study on the efficiency of <span class="hlt">aerosol</span> indirect effect indicates that a large</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A12G..05E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A12G..05E"><span>Contrasting Secondary Organic <span class="hlt">Aerosol</span> Formation in <span class="hlt">Aerosol</span> Liquid Water During Summer and Winter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>El-Sayed, M.; Hennigan, C. J.</p> <p>2017-12-01</p> <p>In this study, we characterize the formation of aqueous secondary organic <span class="hlt">aerosols</span> (aqSOA) in the eastern United States during summer and winter. The aim was to identify the main factors affecting the reversible and irreversible uptake of water-soluble organic gases to <span class="hlt">aerosol</span> liquid water under variable influence from biogenic and anthropogenic sources. The reversible and irreversible uptake of water-soluble organic gases to <span class="hlt">aerosol</span> water was measured in Baltimore, MD using a recently developed on-line method. The formation of aqSOA was observed during the summer and the winter; however, the amount of aqSOA varied significantly between the two seasons, as did the reversible and irreversible nature of the uptake. While the availability of <span class="hlt">aerosol</span> liquid water (ALW) predominantly controlled aqSOA formation in the summer, wintertime aqSOA formation was limited by precursor VOCs as well. During the summer, aqSOA formation was tightly linked with isoprene oxidation, while the aqSOA formed in the winter was associated with biomass burning. Irreversible aqSOA was formed in both seasons; however, reversible aqSOA was only observed in the summer. Overall, these results demonstrate the importance of multi-phase chemistry in <span class="hlt">aerosol</span> formation and underscore the significance of soluble organic gases partitioning to <span class="hlt">aerosol</span> water both reversibly and irreversibly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RvGeo..54..866L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RvGeo..54..866L"><span><span class="hlt">Aerosol</span> and monsoon climate interactions over Asia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Zhanqing; Lau, W. K.-M.; Ramanathan, V.; Wu, G.; Ding, Y.; Manoj, M. G.; Liu, J.; Qian, Y.; Li, J.; Zhou, T.; Fan, J.; Rosenfeld, D.; Ming, Y.; Wang, Y.; Huang, J.; Wang, B.; Xu, X.; Lee, S.-S.; Cribb, M.; Zhang, F.; Yang, X.; Zhao, C.; Takemura, T.; Wang, K.; Xia, X.; Yin, Y.; Zhang, H.; Guo, J.; Zhai, P. M.; Sugimoto, N.; Babu, S. S.; Brasseur, G. P.</p> <p>2016-12-01</p> <p>The increasing severity of droughts/floods and worsening air quality from increasing <span class="hlt">aerosols</span> in Asia monsoon regions are the two gravest threats facing over 60% of the world population living in Asian monsoon regions. These dual threats have fueled a large body of research in the last decade on the roles of <span class="hlt">aerosols</span> in impacting Asian monsoon weather and climate. This paper provides a comprehensive review of studies on Asian <span class="hlt">aerosols</span>, monsoons, and their interactions. The Asian monsoon region is a primary source of emissions of diverse species of <span class="hlt">aerosols</span> from both anthropogenic and natural origins. The distributions of <span class="hlt">aerosol</span> loading are strongly influenced by distinct weather and climatic regimes, which are, in turn, modulated by <span class="hlt">aerosol</span> effects. On a continental scale, <span class="hlt">aerosols</span> reduce surface insolation and weaken the land-ocean thermal contrast, thus inhibiting the development of monsoons. Locally, <span class="hlt">aerosol</span> radiative effects alter the thermodynamic stability and convective potential of the lower atmosphere leading to reduced temperatures, increased atmospheric stability, and weakened wind and atmospheric circulations. The atmospheric thermodynamic state, which determines the formation of clouds, convection, and precipitation, may also be altered by <span class="hlt">aerosols</span> serving as cloud condensation nuclei or ice nuclei. Absorbing <span class="hlt">aerosols</span> such as black carbon and desert dust in Asian monsoon regions may also induce dynamical feedback processes, leading to a strengthening of the early monsoon and affecting the subsequent evolution of the monsoon. Many mechanisms have been put forth regarding how <span class="hlt">aerosols</span> modulate the amplitude, frequency, intensity, and phase of different monsoon climate variables. A wide range of theoretical, observational, and modeling findings on the Asian monsoon, <span class="hlt">aerosols</span>, and their interactions are synthesized. A new paradigm is proposed on investigating <span class="hlt">aerosol</span>-monsoon interactions, in which natural <span class="hlt">aerosols</span> such as desert dust, black carbon from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080023775','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080023775"><span>The <span class="hlt">Aerosol</span>/Cloud/Ecosystems Mission (ACE)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schoeberl, Mark</p> <p>2008-01-01</p> <p>The goals and measurement strategy of the <span class="hlt">Aerosol</span>/Cloud/Ecosystems Mission (ACE) are described. ACE will help to answer fundamental science questions associated with <span class="hlt">aerosols</span>, clouds, air quality and global ocean ecosystems. Specifically, the goals of ACE are: 1) to quantify <span class="hlt">aerosol</span>-cloud interactions and to assess the impact of <span class="hlt">aerosols</span> on the hydrological cycle and 2) determine Ocean Carbon Cycling and other ocean biological processes. It is expected that ACE will: narrow the uncertainty in <span class="hlt">aerosol</span>-cloud-precipitation interaction and quantify the role of <span class="hlt">aerosols</span> in climate change; measure the ocean ecosystem changes and precisely quantify ocean carbon uptake; and, improve air quality forecasting by determining the height and type of <span class="hlt">aerosols</span> being transported long distances. Overviews are provided of the <span class="hlt">aerosol</span>-cloud community measurement strategy, <span class="hlt">aerosol</span> and cloud observations over South Asia, and ocean biology research goals. Instruments used in the measurement strategy of the ACE mission are also highlighted, including: multi-beam lidar, multiwavelength high spectra resolution lidar, the ocean color instrument (ORCA)--a spectroradiometer for ocean remote sensing, dual frequency cloud radar and high- and low-frequency micron-wave radiometer. Future steps for the ACE mission include refining measurement requirements and carrying out additional instrument and payload studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AtmEn.158..236C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AtmEn.158..236C"><span>Time-resolved analysis of primary volatile emissions and secondary <span class="hlt">aerosol</span> formation potential from a small-scale pellet boiler</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Czech, Hendryk; Pieber, Simone M.; Tiitta, Petri; Sippula, Olli; Kortelainen, Miika; Lamberg, Heikki; Grigonyte, Julija; Streibel, Thorsten; Prévôt, André S. H.; Jokiniemi, Jorma; Zimmermann, Ralf</p> <p>2017-06-01</p> <p>Small-scale pellet boilers and stoves became popular as a wood combustion appliance for domestic heating in Europe, North America and Asia due to economic and environmental aspects. Therefore, an increasing contribution of pellet boilers to air pollution is expected despite their general high combustion efficiency. As emissions of primary organic <span class="hlt">aerosol</span> (POA) and permanent gases of pellet boilers are well investigated, the scope of this study was to investigate the volatile organic emissions and the formation potential of secondary <span class="hlt">aerosols</span> for this type of appliance. Fresh and aged emissions were analysed by a soot-particle <span class="hlt">aerosol</span> time-of-flight mass spectrometry (SP-AMS) and the molecular composition of the volatile precursors with single-photon ionisation time-of-flight mass spectrometry (SPI-TOFMS) at different pellet boiler operation conditions. Organic emissions in the gas phase were dominated by unsaturated hydrocarbons while wood-specific VOCs, e.g. phenolic species or <span class="hlt">substituted</span> furans, were only detected during the starting phase. Furthermore, organic emissions in the gas phase were found to correlate with fuel grade and combustion technology in terms of secondary air supply. Secondary organic <span class="hlt">aerosols</span> of optimised pellet boiler conditions (OPT, state-of-the-art combustion appliance) and reduced secondary air supply (RSA, used as a proxy for pellet boilers of older type) were studied by simulating atmospheric ageing in a Potential <span class="hlt">Aerosol</span> Mass (PAM) flow reactor. Different increases in OA mass (55% for OPT, 102% for RSA), associated with higher average carbon oxidation state and O:C, could be observed in a PAM chamber experiment. Finally, it was found that derived SOA yields and emission factors were distinctly lower than reported for log wood stoves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5020605','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5020605"><span>Evaluations of tropospheric <span class="hlt">aerosol</span> properties simulated by the community earth system model with a sectional <span class="hlt">aerosol</span> microphysics scheme</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Toon, Owen B.; Bardeen, Charles G.; Mills, Michael J.; Fan, Tianyi; English, Jason M.; Neely, Ryan R.</p> <p>2015-01-01</p> <p>Abstract A sectional <span class="hlt">aerosol</span> model (CARMA) has been developed and coupled with the Community Earth System Model (CESM1). <span class="hlt">Aerosol</span> microphysics, radiative properties, and interactions with clouds are simulated in the size‐resolving model. The model described here uses 20 particle size bins for each <span class="hlt">aerosol</span> component including freshly nucleated sulfate particles, as well as mixed particles containing sulfate, primary organics, black carbon, dust, and sea salt. The model also includes five types of bulk secondary organic <span class="hlt">aerosols</span> with four volatility bins. The overall cost of CESM1‐CARMA is approximately ∼2.6 times as much computer time as the standard three‐mode <span class="hlt">aerosol</span> model in CESM1 (CESM1‐MAM3) and twice as much computer time as the seven‐mode <span class="hlt">aerosol</span> model in CESM1 (CESM1‐MAM7) using similar gas phase chemistry codes. <span class="hlt">Aerosol</span> spatial‐temporal distributions are simulated and compared with a large set of observations from satellites, ground‐based measurements, and airborne field campaigns. Simulated annual average <span class="hlt">aerosol</span> optical depths are lower than MODIS/MISR satellite observations and AERONET observations by ∼32%. This difference is within the uncertainty of the satellite observations. CESM1/CARMA reproduces sulfate <span class="hlt">aerosol</span> mass within 8%, organic <span class="hlt">aerosol</span> mass within 20%, and black carbon <span class="hlt">aerosol</span> mass within 50% compared with a multiyear average of the IMPROVE/EPA data over United States, but differences vary considerably at individual locations. Other data sets show similar levels of comparison with model simulations. The model suggests that in addition to sulfate, organic <span class="hlt">aerosols</span> also significantly contribute to <span class="hlt">aerosol</span> mass in the tropical UTLS, which is consistent with limited data. PMID:27668039</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5946319','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5946319"><span>Spatiotemporal variability and contribution of different <span class="hlt">aerosol</span> types to the <span class="hlt">Aerosol</span> Optical Depth over the Eastern Mediterranean</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Georgoulias, Aristeidis K.; Alexandri, Georgia; Kourtidis, Konstantinos A.; Lelieveld, Jos; Zanis, Prodromos; Pöschl, Ulrich; Levy, Robert; Amiridis, Vassilis; Marinou, Eleni; Tsikerdekis, Athanasios</p> <p>2018-01-01</p> <p>This study characterizes the spatiotemporal variability and relative contribution of different types of <span class="hlt">aerosols</span> to the <span class="hlt">Aerosol</span> Optical Depth (AOD) over the Eastern Mediterranean as derived from MODIS Terra (3/2000–12/2012) and Aqua (7/2002–12/2012) satellite instruments. For this purpose, a 0.1° × 0.1° gridded MODIS dataset was compiled and validated against sunphotometric observations from the <span class="hlt">AErosol</span> RObotic NETwork (AERONET). The high spatial resolution and long temporal coverage of the dataset allows for the determination of local hot spots like megacities, medium sized cities, industrial zones, and power plant complexes, seasonal variabilities, and decadal averages. The average AOD at 550 nm (AOD550) for the entire region is ~ 0.22 ± 0.19 with maximum values in summer and seasonal variabilities that can be attributed to precipitation, photochemical production of secondary organic <span class="hlt">aerosols</span>, transport of pollution and smoke from biomass burning in Central and Eastern Europe, and transport of dust from the Sahara Desert and the Middle East. The MODIS data were analyzed together with data from other satellite sensors, reanalysis projects and a chemistry-<span class="hlt">aerosol</span>-transport model using an optimized algorithm tailored for the region and capable of estimating the contribution of different <span class="hlt">aerosol</span> types to the total AOD550. The spatial and temporal variability of anthropogenic, dust and fine mode natural <span class="hlt">aerosols</span> over land and anthropogenic, dust and marine <span class="hlt">aerosols</span> over the sea is examined. The relative contribution of the different <span class="hlt">aerosol</span> types to the total AOD550 exhibits a low/high seasonal variability over land/sea areas, respectively. Overall, anthropogenic <span class="hlt">aerosols</span>, dust and fine mode natural <span class="hlt">aerosols</span> account for ~ 51 %, ~ 34 % and ~ 15 % of the total AOD550 over land, while, anthropogenic <span class="hlt">aerosols</span>, dust and marine <span class="hlt">aerosols</span> account ~ 40 %, ~ 34 % and ~ 26 % of the total AOD550 over the sea, based on MODIS Terra and Aqua observations. PMID:29755508</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ACP....1613853G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ACP....1613853G"><span>Spatiotemporal variability and contribution of different <span class="hlt">aerosol</span> types to the <span class="hlt">aerosol</span> optical depth over the Eastern Mediterranean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Georgoulias, Aristeidis K.; Alexandri, Georgia; Kourtidis, Konstantinos A.; Lelieveld, Jos; Zanis, Prodromos; Pöschl, Ulrich; Levy, Robert; Amiridis, Vassilis; Marinou, Eleni; Tsikerdekis, Athanasios</p> <p>2016-11-01</p> <p>This study characterizes the spatiotemporal variability and relative contribution of different types of <span class="hlt">aerosols</span> to the <span class="hlt">aerosol</span> optical depth (AOD) over the Eastern Mediterranean as derived from MODIS (Moderate Resolution Imaging Spectroradiometer) Terra (March 2000-December 2012) and Aqua (July 2002-December 2012) satellite instruments. For this purpose, a 0.1° × 0.1° gridded MODIS dataset was compiled and validated against sun photometric observations from the <span class="hlt">AErosol</span> RObotic NETwork (AERONET). The high spatial resolution and long temporal coverage of the dataset allows for the determination of local hot spots like megacities, medium-sized cities, industrial zones and power plant complexes, seasonal variabilities and decadal averages. The average AOD at 550 nm (AOD550) for the entire region is ˜ 0.22 ± 0.19, with maximum values in summer and seasonal variabilities that can be attributed to precipitation, photochemical production of secondary organic <span class="hlt">aerosols</span>, transport of pollution and smoke from biomass burning in central and eastern Europe and transport of dust from the Sahara and the Middle East. The MODIS data were analyzed together with data from other satellite sensors, reanalysis projects and a chemistry-<span class="hlt">aerosol</span>-transport model using an optimized algorithm tailored for the region and capable of estimating the contribution of different <span class="hlt">aerosol</span> types to the total AOD550. The spatial and temporal variability of anthropogenic, dust and fine-mode natural <span class="hlt">aerosols</span> over land and anthropogenic, dust and marine <span class="hlt">aerosols</span> over the sea is examined. The relative contribution of the different <span class="hlt">aerosol</span> types to the total AOD550 exhibits a low/high seasonal variability over land/sea areas, respectively. Overall, anthropogenic <span class="hlt">aerosols</span>, dust and fine-mode natural <span class="hlt">aerosols</span> account for ˜ 51, ˜ 34 and ˜ 15 % of the total AOD550 over land, while, anthropogenic <span class="hlt">aerosols</span>, dust and marine <span class="hlt">aerosols</span> account ˜ 40, ˜ 34 and ˜ 26 % of the total AOD550 over the sea, based on</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170010207','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170010207"><span>Spatiotemporal Variability and Contribution of Different <span class="hlt">Aerosol</span> Types to the <span class="hlt">Aerosol</span> Optical Depth over the Eastern Mediterranean</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Georgoulias, Aristeidis K.; Alexandri, Georgia; Kourtidis, Konstantinos A.; Lelieveld, Jos; Zanis, Prodromos; Poeschl, Ulrich; Levy, Robert; Amiridis, Vassilis; Marinou, Eleni; Tsikerdekis, Athanasios</p> <p>2016-01-01</p> <p>This study characterizes the spatiotemporal variability and relative contribution of different types of <span class="hlt">aerosols</span> to the <span class="hlt">aerosol</span> optical depth (AOD) over the Eastern Mediterranean as derived from MODIS (Moderate Resolution Imaging Spectroradiometer) Terra (March 2000-December 2012) and Aqua (July 2002-December 2012) satellite instruments. For this purpose, a 0.1deg × 0.1deg gridded MODIS dataset was compiled and validated against sun photometric observations from the <span class="hlt">AErosol</span> RObotic NETwork (AERONET). The high spatial resolution and long temporal coverage of the dataset allows for the determination of local hot spots like megacities, medium-sized cities, industrial zones and power plant complexes, seasonal variabilities and decadal averages. The average AOD at 550 nm (AOD550) for the entire region is approx. 0.22 +/- 0.19, with maximum values in summer and seasonal variabilities that can be attributed to precipitation, photochemical production of secondary organic <span class="hlt">aerosols</span>, transport of pollution and smoke from biomass burning in central and eastern Europe and transport of dust from the Sahara and the Middle East. The MODIS data were analyzed together with data from other satellite sensors, reanalysis projects and a chemistry-<span class="hlt">aerosol</span>-transport model using an optimized algorithm tailored for the region and capable of estimating the contribution of different <span class="hlt">aerosol</span> types to the total AOD550. The spatial and temporal variability of anthropogenic, dust and fine-mode natural <span class="hlt">aerosols</span> over land and anthropogenic, dust and marine <span class="hlt">aerosols</span> over the sea is examined. The relative contribution of the different <span class="hlt">aerosol</span> types to the total AOD550 exhibits a low/high seasonal variability over land/sea areas, respectively. Overall, anthropogenic <span class="hlt">aerosols</span>, dust and fine-mode natural <span class="hlt">aerosols</span> account for approx. 51, approx. 34 and approx. 15 % of the total AOD550 over land, while, anthropogenic <span class="hlt">aerosols</span>, dust and marine <span class="hlt">aerosols</span> account approx. 40, approx. 34 and approx. 26 % of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760014655','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760014655"><span>A thermoluminescent method for <span class="hlt">aerosol</span> characterization</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Long, E. R., Jr.; Rogowski, R. S.</p> <p>1976-01-01</p> <p>A thermoluminescent method has been used to study the interactions of <span class="hlt">aerosols</span> with ozone. The preliminary results show that ozone reacts with many compounds found in <span class="hlt">aerosols</span>, and that the thermoluminescence curves obtained from ozonated <span class="hlt">aerosols</span> are characteristic of the <span class="hlt">aerosol</span>. The results suggest several important applications of the thermoluminescent method: development of a detector for identification of effluent sources; a sensitive experimental tool for study of heterogeneous chemistry; evaluation of importance of <span class="hlt">aerosols</span> in atmospheric chemistry; and study of formation of toxic, electronically excited species in airborne particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930010913','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930010913"><span><span class="hlt">Aerosol</span> chemistry in GLOBE</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Clarke, Antony D.; Rothermel, Jeffry; Jarzembski, Maurice A.</p> <p>1993-01-01</p> <p>This task addresses the measurement and understanding of the physical and chemical properties of <span class="hlt">aerosol</span> in remote regions that are responsible for <span class="hlt">aerosol</span> backscatter at infrared wavelengths. Because it is representative of other clean areas, the remote Pacific is of extreme interest. Emphasis is on the determination size dependent <span class="hlt">aerosol</span> properties that are required for modeling backscatter at various wavelengths and upon those features that may be used to help understand the nature, origin, cycling and climatology of these <span class="hlt">aerosols</span> in the remote troposphere. Empirical relationships will be established between lidar measurements and backscatter derived from the <span class="hlt">aerosol</span> microphysics as required by the NASA Doppler Lidar Program. This will include the analysis of results from the NASA GLOBE Survey Mission Flight Program. Additional instrument development and deployment will be carried out in order to extend and refine this data base. Identified activities include participation in groundbased and airborne experiments. Progress to date includes participation in, analysis of, and publication of results from Mauna Loa Backscatter Intercomparison Experiment (MABIE) and Global Backscatter Experiment (GLOBE).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110015434','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110015434"><span>Workshop Summary: International Cooperative for <span class="hlt">Aerosol</span> Prediction Workshop On <span class="hlt">Aerosol</span> Forecast Verification</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Benedetti, Angela; Reid, Jeffrey S.; Colarco, Peter R.</p> <p>2011-01-01</p> <p>The purpose of this workshop was to reinforce the working partnership between centers who are actively involved in global <span class="hlt">aerosol</span> forecasting, and to discuss issues related to forecast verification. Participants included representatives from operational centers with global <span class="hlt">aerosol</span> forecasting requirements, a panel of experts on Numerical Weather Prediction and Air Quality forecast verification, data providers, and several observers from the research community. The presentations centered on a review of current NWP and AQ practices with subsequent discussion focused on the challenges in defining appropriate verification measures for the next generation of <span class="hlt">aerosol</span> forecast systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170002033&hterms=Organic+Chemical&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DOrganic%2BChemical','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170002033&hterms=Organic+Chemical&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DOrganic%2BChemical"><span>MATRIX-VBS (v1.0): Implementing an Evolving Organic <span class="hlt">Aerosol</span> Volatility in an <span class="hlt">Aerosol</span> Microphysics Model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gao, Chloe Y.; Tsigaridis, Kostas; Bauer, Susanne E.</p> <p>2017-01-01</p> <p>The gas-particle partitioning and chemical aging of semi-volatile organic <span class="hlt">aerosol</span> are presented in a newly developed box model scheme, where its effect on the growth, composition, and mixing state of particles is examined. The volatility-basis set (VBS) framework is implemented into the <span class="hlt">aerosol</span> microphysical scheme MATRIX (Multiconfiguration <span class="hlt">Aerosol</span> TRacker of mIXing state), which resolves mass and number <span class="hlt">aerosol</span> concentrations and in multiple mixing-state classes. The new scheme, MATRIX-VBS, has the potential to significantly advance the representation of organic <span class="hlt">aerosols</span> in Earth system models by improving upon the conventional representation as non-volatile particulate organic matter, often also with an assumed fixed size distribution. We present results from idealized cases representing Beijing, Mexico City, a Finnish forest, and a southeastern US forest, and investigate the evolution of mass concentrations and volatility distributions for organic species across the gas and particle phases, as well as assessing their mixing state among <span class="hlt">aerosol</span> populations. Emitted semi-volatile primary organic <span class="hlt">aerosols</span> evaporate almost completely in the intermediate-volatility range, while they remain in the particle phase in the low-volatility range. Their volatility distribution at any point in time depends on the applied emission factors, oxidation by OH radicals, and temperature. We also compare against parallel simulations with the original scheme, which represented only the particulate and non-volatile component of the organic <span class="hlt">aerosol</span>, examining how differently the condensed-phase organic matter is distributed across the mixing states in the model. The results demonstrate the importance of representing organic <span class="hlt">aerosol</span> as a semi-volatile <span class="hlt">aerosol</span>, and explicitly calculating the partitioning of organic species between the gas and particulate phases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/993659-spatial-temporal-variations-aerosols-around-beijing-summer-local-column-aerosol-optical-properties','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/993659-spatial-temporal-variations-aerosols-around-beijing-summer-local-column-aerosol-optical-properties"><span>Spatial and temporal variations of <span class="hlt">aerosols</span> around Beijing in summer 2006: 2. Local and column <span class="hlt">aerosol</span> optical properties</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Matsui, Hitoshi; Koike, Makoto; Kondo, Yutaka</p> <p></p> <p>Weather Research and Forecasting (WRF)-chem model calculations were conducted to study <span class="hlt">aerosol</span> optical properties around Beijing, China, during the Campaign of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing-2006) period. In this paper, we interpret <span class="hlt">aerosol</span> optical properties in terms of <span class="hlt">aerosol</span> mass concentrations and their chemical compositions by linking model calculations with measurements. In general, model calculations reproduced observed features of spatial and temporal variations of various surface and column <span class="hlt">aerosol</span> optical parameters in and around Beijing. Spatial and temporal variations of <span class="hlt">aerosol</span> absorption, scattering, and extinction coefficient corresponded well to those of elemental carbon (primary <span class="hlt">aerosol</span>),more » sulfate (secondary <span class="hlt">aerosol</span>), and the total <span class="hlt">aerosol</span> mass concentration, respectively. These results show that spatial and temporal variations of the absorption coefficient are controlled by local emissions (within 100 km around Beijing during the preceding 24 h), while those of the scattering coefficient are controlled by regional-scale emissions (within 500 km around Beijing during the preceding 3 days) under synoptic-scale meteorological conditions, as discussed in our previous study of <span class="hlt">aerosol</span> mass concentration. Vertical profiles of <span class="hlt">aerosol</span> extinction revealed that the contribution of secondary <span class="hlt">aerosols</span> and their water uptake increased with altitude within the planetary boundary layer, leading to a considerable increase in column <span class="hlt">aerosol</span> optical depth (AOD) around Beijing. These effects are the main factors causing differences in regional and temporal variations between particulate matter (PM) mass concentration at the surface and column AOD over a wide region in the northern part of the Great North China Plain.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A41F3114A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A41F3114A"><span>The <span class="hlt">Aerosol</span> Coarse Mode Initiative</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arnott, W. P.; Adhikari, N.; Air, D.; Kassianov, E.; Barnard, J.</p> <p>2014-12-01</p> <p>Many areas of the world show an <span class="hlt">aerosol</span> volume distribution with a significant coarse mode and sometimes a dominant coarse mode. The large coarse mode is usually due to dust, but sea salt <span class="hlt">aerosol</span> can also play an important role. However, in many field campaigns, the coarse mode tends to be ignored, because it is difficult to measure. This lack of measurements leads directly to a concomitant "lack of analysis" of this mode. Because, coarse mode <span class="hlt">aerosols</span> can have significant effects on radiative forcing, both in the shortwave and longwave spectrum, the coarse mode -- and these forcings -- should be accounted for in atmospheric models. Forcings based only on fine mode <span class="hlt">aerosols</span> have the potential to be misleading. In this paper we describe examples of large coarse modes that occur in areas of large <span class="hlt">aerosol</span> loading (Mexico City, Barnard et al., 2010) as well as small loadings (Sacramento, CA; Kassianov et al., 2012; and Reno, NV). We then demonstrate that: (1) the coarse mode can contribute significantly to radiative forcing, relative to the fine mode, and (2) neglecting the coarse mode may result in poor comparisons between measurements and models. Next we describe -- in general terms -- the limitations of instrumentation to measure the coarse mode. Finally, we suggest a new initiative aimed at examining coarse mode <span class="hlt">aerosol</span> generation mechanisms; transport and deposition; chemical composition; visible and thermal IR refractive indices; morphology; microphysical behavior when deposited on snow and ice; and specific instrumentation needs. Barnard, J. C., J. D. Fast, G. Paredes-Miranda, W. P. Arnott, and A. Laskin, 2010: Technical Note: Evaluation of the WRF-Chem "<span class="hlt">Aerosol</span> Chemical to <span class="hlt">Aerosol</span> Optical Properties" Module using data from the MILAGRO campaign, Atmospheric Chemistry and Physics, 10, 7325-7340. Kassianov, E. I., M. S. Pekour, and J. C. Barnard, 2012: <span class="hlt">Aerosols</span> in Central California: Unexpectedly large contribution of coarse mode to <span class="hlt">aerosol</span> radiative forcing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3204795','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3204795"><span><span class="hlt">Aerosol</span> Therapy for Obstructive Lung Diseases</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2011-01-01</p> <p>Inhaled <span class="hlt">aerosol</span> therapies are the mainstay of treatment of obstructive lung diseases. <span class="hlt">Aerosol</span> devices deliver drugs rapidly and directly into the airways, allowing high local drug concentrations while limiting systemic toxicity. While numerous clinical trials, literature reviews, and expert panel guidelines inform the choice of inhalational drugs, deciding which <span class="hlt">aerosol</span> device (ie, metered-dose inhaler, nebulizer, or dry powder inhaler) best suits a given patient and clinical setting can seem arbitrary and confusing. Similar confusion regarding Current Procedural Terminology (CPT) coding for administration of <span class="hlt">aerosol</span> therapies can lead to lost revenue from underbilling and wasted administrative effort handling denied claims. This article reviews the <span class="hlt">aerosol</span> devices currently available, discusses their relative merits in various clinical settings, and summarizes appropriate CPT coding for <span class="hlt">aerosol</span> therapy. PMID:21896522</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7670700','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7670700"><span>A novel ultrasonic <span class="hlt">aerosol</span> generator.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Davies, A; Hudson, N; Pirie, L</p> <p>1995-07-01</p> <p>An ultrasonic <span class="hlt">aerosol</span> generator constructed from a domestic humidifier is described which has been used to produce liquid <span class="hlt">aerosols</span> for physiological investigations. The instrument was constructed from a Pifco domestic humidifier modified to include an energy guide to direct the oscillations of the transducer through the coupling water, which would normally be <span class="hlt">aerosolized</span>, onto a small membrane based sample chamber containing the liquid to be <span class="hlt">aerosolized</span>. The size distribution of the <span class="hlt">aerosol</span> produced was found to be between 2 and 6 mm, optimum for diffuse intrapulmonary deposition. Up to 4 ml/min of aqueous liquid was used; however the sample chamber could be made small enough to contain economic amounts of expensive material to administer by inhalation. The instrument has proved to be reliable over a period of three years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020039742&hterms=extinction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dextinction','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020039742&hterms=extinction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dextinction"><span>In Situ Measurement of <span class="hlt">Aerosol</span> Extinction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Strawa, Anthony W.; Castaneda, R.; Owano, T. G.; Bear, D.; Gore, Warren J. (Technical Monitor)</p> <p>2001-01-01</p> <p><span class="hlt">Aerosols</span> are important contributors to the radiative forcing in the atmosphere. Much of the uncertainty in our knowledge of climate forcing is due to uncertainties in the radiative forcing due to <span class="hlt">aerosols</span> as illustrated in the IPCC reports of the last ten years. Improved measurement of <span class="hlt">aerosol</span> optical properties, therefore, is critical to an improved understanding of atmospheric radiative forcing. Additionally, attempts to reconcile in situ and remote measurements of <span class="hlt">aerosol</span> radiative properties have generally not been successful. This is due in part to the fact that it has been impossible to measure <span class="hlt">aerosol</span> extinction in situ in the past. In this presentation we introduce a new instrument that employs the techniques used in cavity ringdown spectroscopy to measure the <span class="hlt">aerosol</span> extinction and scattering coefficients in situ. A prototype instrument has been designed and tested in the lab and the field. It is capable of measuring <span class="hlt">aerosol</span> extinction coefficient to 2x10(exp -6) per meter. This prototype instrument is described and results are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A51G2147F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A51G2147F"><span>What is the impact of natural variability and <span class="hlt">aerosol</span>-cloud interaction on the effective radiative forcing of anthropogenic <span class="hlt">aerosol</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fiedler, S.; Stevens, B.; Mauritsen, T.</p> <p>2017-12-01</p> <p>State-of-the-art climate models have persistently shown a spread in estimates of the effective radiative forcing (ERF) associated with anthropogenic <span class="hlt">aerosol</span>. Different reasons for the spread are known, but their relative importance is poorly understood. In this presentation we investigate the role of natural atmospheric variability, global patterns of <span class="hlt">aerosol</span> radiative effects, and magnitudes of <span class="hlt">aerosol</span>-cloud interaction in controlling the ERF of anthropogenic <span class="hlt">aerosol</span> (Fiedler et al., 2017). We use the Earth system model MPI-ESM1.2 for conducting ensembles of atmosphere-only simulations and calculate the shortwave ERF of anthropogenic <span class="hlt">aerosol</span> at the top of the atmosphere. The radiative effects are induced with the new parameterisation MACv2-SP (Stevens et al., 2017) that prescribes observationally constrained anthropogenic <span class="hlt">aerosol</span> optical properties and an associated Twomey effect. Firstly, we compare the ERF of global patterns of anthropogenic <span class="hlt">aerosol</span> from the mid-1970s and today. Our results suggest that such a substantial pattern difference has a negligible impact on the global mean ERF, when the natural variability of the atmosphere is considered. The clouds herein efficiently mask the clear-sky contributions to the forcing and reduce the detectability of significant anthropogenic <span class="hlt">aerosol</span> radiative effects in all-sky conditions. Secondly, we strengthen the forcing magnitude through increasing the effect of <span class="hlt">aerosol</span>-cloud interaction by prescribing an enhanced Twomey effect. In that case, the different spatial pattern of <span class="hlt">aerosol</span> radiative effects from the mid-1970s and today causes a moderate change (15%) in the ERF of anthropogenic <span class="hlt">aerosol</span> in our model. This finding lets us speculate that models with strong <span class="hlt">aerosol</span>-cloud interactions would show a stronger ERF change with anthropogenic <span class="hlt">aerosol</span> patterns. Testing whether the anthropogenic <span class="hlt">aerosol</span> radiative forcing is model-dependent under prescribed <span class="hlt">aerosol</span> conditions is currently ongoing work using MACv2-SP in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130013402','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130013402"><span>Satellite Remote Sensing: <span class="hlt">Aerosol</span> Measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kahn, Ralph A.</p> <p>2013-01-01</p> <p><span class="hlt">Aerosols</span> are solid or liquid particles suspended in the air, and those observed by satellite remote sensing are typically between about 0.05 and 10 microns in size. (Note that in traditional <span class="hlt">aerosol</span> science, the term "<span class="hlt">aerosol</span>" refers to both the particles and the medium in which they reside, whereas for remote sensing, the term commonly refers to the particles only. In this article, we adopt the remote-sensing definition.) They originate from a great diversity of sources, such as wildfires, volcanoes, soils and desert sands, breaking waves, natural biological activity, agricultural burning, cement production, and fossil fuel combustion. They typically remain in the atmosphere from several days to a week or more, and some travel great distances before returning to Earth's surface via gravitational settling or washout by precipitation. Many <span class="hlt">aerosol</span> sources exhibit strong seasonal variability, and most experience inter-annual fluctuations. As such, the frequent, global coverage that space-based <span class="hlt">aerosol</span> remote-sensing instruments can provide is making increasingly important contributions to regional and larger-scale <span class="hlt">aerosol</span> studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120003903','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120003903"><span>Multi-Sensor <span class="hlt">Aerosol</span> Products Sampling System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Petrenko, M.; Ichoku, C.; Leptoukh, G.</p> <p>2011-01-01</p> <p>Global and local properties of atmospheric <span class="hlt">aerosols</span> have been extensively observed and measured using both spaceborne and ground-based instruments, especially during the last decade. Unique properties retrieved by the different instruments contribute to an unprecedented availability of the most complete set of complimentary <span class="hlt">aerosol</span> measurements ever acquired. However, some of these measurements remain underutilized, largely due to the complexities involved in analyzing them synergistically. To characterize the inconsistencies and bridge the gap that exists between the sensors, we have established a Multi-sensor <span class="hlt">Aerosol</span> Products Sampling System (MAPSS), which consistently samples and generates the spatial statistics (mean, standard deviation, direction and rate of spatial variation, and spatial correlation coefficient) of <span class="hlt">aerosol</span> products from multiple spacebome sensors, including MODIS (on Terra and Aqua), MISR, OMI, POLDER, CALIOP, and SeaWiFS. Samples of satellite <span class="hlt">aerosol</span> products are extracted over <span class="hlt">Aerosol</span> Robotic Network (AERONET) locations as well as over other locations of interest such as those with available ground-based <span class="hlt">aerosol</span> observations. In this way, MAPSS enables a direct cross-characterization and data integration between Level-2 <span class="hlt">aerosol</span> observations from multiple sensors. In addition, the available well-characterized co-located ground-based data provides the basis for the integrated validation of these products. This paper explains the sampling methodology and concepts used in MAPSS, and demonstrates specific examples of using MAPSS for an integrated analysis of multiple <span class="hlt">aerosol</span> products.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1259759','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1259759"><span>Unique DNA-barcoded <span class="hlt">aerosol</span> test particles for studying <span class="hlt">aerosol</span> transport</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Harding, Ruth N.; Hara, Christine A.; Hall, Sara B.</p> <p></p> <p>Data are presented for the first use of novel DNA-barcoded <span class="hlt">aerosol</span> test particles that have been developed to track the fate of airborne contaminants in populated environments. Until DNATrax (DNA Tagged Reagents for <span class="hlt">Aerosol</span> eXperiments) particles were developed, there was no way to rapidly validate air transport models with realistic particles in the respirable range of 1–10 μm in diameter. The DNATrax particles, developed at Lawrence Livermore National Laboratory (LLNL) and tested with the assistance of the Pentagon Force Protection Agency, are the first safe and effective materials for <span class="hlt">aerosol</span> transport studies that are identified by DNA molecules. The usemore » of unique synthetic DNA barcodes overcomes the challenges of discerning the test material from pre-existing environmental or background contaminants (either naturally occurring or previously released). The DNATrax particle properties are demonstrated to have appropriate size range (approximately 1–4.5 μm in diameter) to accurately simulate bacterial spore transport. As a result, we describe details of the first field test of the DNATrax <span class="hlt">aerosol</span> test particles in a large indoor facility.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1259759-unique-dna-barcoded-aerosol-test-particles-studying-aerosol-transport','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1259759-unique-dna-barcoded-aerosol-test-particles-studying-aerosol-transport"><span>Unique DNA-barcoded <span class="hlt">aerosol</span> test particles for studying <span class="hlt">aerosol</span> transport</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Harding, Ruth N.; Hara, Christine A.; Hall, Sara B.; ...</p> <p>2016-03-22</p> <p>Data are presented for the first use of novel DNA-barcoded <span class="hlt">aerosol</span> test particles that have been developed to track the fate of airborne contaminants in populated environments. Until DNATrax (DNA Tagged Reagents for <span class="hlt">Aerosol</span> eXperiments) particles were developed, there was no way to rapidly validate air transport models with realistic particles in the respirable range of 1–10 μm in diameter. The DNATrax particles, developed at Lawrence Livermore National Laboratory (LLNL) and tested with the assistance of the Pentagon Force Protection Agency, are the first safe and effective materials for <span class="hlt">aerosol</span> transport studies that are identified by DNA molecules. The usemore » of unique synthetic DNA barcodes overcomes the challenges of discerning the test material from pre-existing environmental or background contaminants (either naturally occurring or previously released). The DNATrax particle properties are demonstrated to have appropriate size range (approximately 1–4.5 μm in diameter) to accurately simulate bacterial spore transport. As a result, we describe details of the first field test of the DNATrax <span class="hlt">aerosol</span> test particles in a large indoor facility.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.A23C0973K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.A23C0973K"><span>Introduction of the new concept: Potential <span class="hlt">Aerosol</span> Mass (PAM) for Inorganic and Organic Secondary <span class="hlt">Aerosol</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kang, E.; Root, M. J.; Brune, W. H.</p> <p>2006-12-01</p> <p>A new concept, the Potential <span class="hlt">Aerosol</span> Mass (PAM), is being developed and tested in the laboratory with the goal of deploying instruments to measure PAM in the atmosphere. PAM can be defined as the maximum <span class="hlt">aerosol</span> mass that precursor gases can be oxidized to form. In the PAM concept, all precursor gases are oxidized to low volatile compounds with excessive amount of oxidants in a small continuous-flow Teflon cylinder, resulting in <span class="hlt">aerosol</span> formation. Excessive amounts of OH and O3 are produced by a UV light that shines into the Teflon chamber. For our studies, the <span class="hlt">aerosol</span> mass is then detected with a real-time <span class="hlt">aerosol</span> mass measurement instrument, the Rupprecht and Patashnick Tapered Element Oscillating Microbalance (TEOM) and Filter Dynamic Measurement System (FDMS). As a test of the system, SO2 was oxidized to sulfate; the measured and calculated conversion ratios of sulfate <span class="hlt">aerosol</span> mass to SO2 mass agree to within 10%. We will discuss the results of a series of laboratory tests that have been conducted with α-pinene to determine the variables that most affect its Secondary Organic <span class="hlt">Aerosol</span> (SOA) yield. We will also discuss the results of some atmospheric measurement tests made at a site on the Penn State University campus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A23K0393K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A23K0393K"><span>The Chemical Composition and Mixing State of Sea Spray <span class="hlt">Aerosol</span> and Organic <span class="hlt">Aerosol</span> in the Winter-Spring Arctic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kirpes, R.; Bondy, A. L.; Bonanno, D.; Moffet, R.; Wang, B.; Laskin, A.; Ault, A. P.; Pratt, K.</p> <p>2016-12-01</p> <p>The Arctic region is undergoing rapid transformations and loss of sea ice due to climate change. With increased sea ice fracturing resulting in greater open ocean surface, winter emissions of sea spray <span class="hlt">aerosol</span> (SSA) are expected to be increasing. Additionally, during the winter-spring transition, Arctic haze contributes to the Arctic <span class="hlt">aerosol</span> budget. The magnitude of <span class="hlt">aerosol</span> climate effects depends on the <span class="hlt">aerosol</span> composition and mixing state (distribution of chemical species within and between particles). However, few studies of <span class="hlt">aerosol</span> chemistry have been conducted in the winter Arctic, despite it being