scholarly journals Lifecycle of light-absorbing carbonaceous aerosols in the atmosphere

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Dantong Liu ◽  
Cenlin He ◽  
Joshua P. Schwarz ◽  
Xuan Wang
Keyword(s):  
Optical Properties ◽  
Radiative Forcing ◽  
Water Solubility ◽  
Model Performance ◽  
Global Scale ◽  
Climate Impacts ◽  
Carbonaceous Aerosols ◽  
Earth System ◽  
The Earth ◽  
Improved Model

Abstract Light-absorbing carbonaceous aerosols (LACs), including black carbon and light-absorbing organic carbon (brown carbon, BrC), have an important role in the Earth system via heating the atmosphere, dimming the surface, modifying the dynamics, reducing snow/ice albedo, and exerting positive radiative forcing. The lifecycle of LACs, from emission to atmospheric evolution further to deposition, is key to their overall climate impacts and uncertainties in determining their hygroscopic and optical properties, atmospheric burden, interactions with clouds, and deposition on the snowpack. At present, direct observations constraining some key processes during the lifecycle of LACs (e.g., interactions between LACs and hydrometeors) are rather limited. Large inconsistencies between directly measured LAC properties and those used for model evaluations also exist. Modern models are starting to incorporate detailed aerosol microphysics to evaluate transformation rates of water solubility, chemical composition, optical properties, and phases of LACs, which have shown improved model performance. However, process-level understanding and modeling are still poor particularly for BrC, and yet to be sufficiently assessed due to lack of global-scale direct measurements. Appropriate treatments of size- and composition-resolved processes that influence both LAC microphysics and aerosol–cloud interactions are expected to advance the quantification of aerosol light absorption and climate impacts in the Earth system. This review summarizes recent advances and up-to-date knowledge on key processes during the lifecycle of LACs, highlighting the essential issues where measurements and modeling need improvement.

scholarly journals The mixing state of carbonaceous aerosol particles in northern and southern California measured during CARES and CalNex 2010

2012 ◽  
Vol 12 (22) ◽  
pp. 10989-11002 ◽  
Author(s):  
J. F. Cahill ◽  
K. Suski ◽  
J. H. Seinfeld ◽  
R. A. Zaveri ◽  
K. A. Prather
Keyword(s):  
Optical Properties ◽  
Radiative Forcing ◽  
Southern California ◽  
Climate Impacts ◽  
Carbonaceous Aerosol ◽  
Carbonaceous Aerosols ◽  
Northern California ◽  
Mixing State ◽  
Carbonaceous Particles ◽  
Secondary Species

Abstract. Carbonaceous aerosols impact climate directly by scattering and absorbing radiation, and hence play a major, although highly uncertain, role in global radiative forcing. Commonly, ambient carbonaceous aerosols are internally mixed with secondary species such as nitrate, sulfate, and ammonium, which influences their optical properties, hygroscopicity, and atmospheric lifetime, thus impacting climate forcing. Aircraft-aerosol time-of-flight mass spectrometry (A-ATOFMS), which measures single-particle mixing state, was used to determine the fraction of organic and soot aerosols that are internally mixed and the variability of their mixing state in California during the Carbonaceous Aerosols and Radiative Effects Study (CARES) and the Research at the Nexus of Air Quality and Climate Change (CalNex) field campaigns in the late spring and early summer of 2010. Nearly 88% of all A-ATOFMS measured particles (100–1000 nm in diameter) were internally mixed with secondary species, with 96% and 75% of particles internally mixed with nitrate and/or sulfate in southern and northern California, respectively. Even though atmospheric particle composition in both regions was primarily influenced by urban sources, the mixing state was found to vary greatly, with nitrate and soot being the dominant species in southern California, and sulfate and organic carbon in northern California. Furthermore, mixing state varied temporally in northern California, with soot becoming the prevalent particle type towards the end of the study as regional pollution levels increased. The results from these studies demonstrate that the majority of ambient carbonaceous particles in California are internally mixed and are heavily influenced by secondary species that are most prevalent in the particular region. Based on these findings, considerations of regionally dominant sources and secondary species, as well as temporal variations of aerosol physical and optical properties, will be required to obtain more accurate predictions of the climate impacts of aerosol in California.

scholarly journals The mixing state of carbonaceous aerosol particles in Northern and Southern California measured during CARES and CalNex 2010

2012 ◽  
Vol 12 (7) ◽  
pp. 18419-18457 ◽  
Author(s):  
J. F. Cahill ◽  
K. Suski ◽  
J. H. Seinfeld ◽  
R. A. Zaveri ◽  
K. A. Prather
Keyword(s):  
Optical Properties ◽  
Radiative Forcing ◽  
Southern California ◽  
Climate Impacts ◽  
Carbonaceous Aerosol ◽  
Carbonaceous Aerosols ◽  
Northern California ◽  
Mixing State ◽  
Carbonaceous Particles ◽  
Secondary Species

Abstract. Carbonaceous aerosols impact climate directly by scattering and absorbing radiation, and hence play a major, although highly uncertain, role in global radiative forcing. Commonly, ambient carbonaceous aerosols are internally mixed with secondary species such as nitrate, sulfate, and ammonium, which influences their optical properties, hygroscopicity, and atmospheric lifetime, thus impacting climate forcing. Aircraft-aerosol time-of-flight mass spectrometry (A-ATOFMS), which measures single-particle mixing state, was used to determine the fraction of organic and soot aerosols that are internally mixed and the variability of their mixing state in California during the Carbonaceous Aerosols and Radiative Effects Study (CARES) and the Research at the Nexus of Air Quality and Climate Change (CalNex) field campaigns in the late spring and early summer of 2010. Nearly 88% of all A-ATOFMS measured particles (100–1000 nm in diameter) were internally mixed with secondary species, with 96% and 75% of particles internally mixed with nitrate and/or sulfate in Southern and Northern California, respectively. Even though atmospheric particle composition in both regions was primarily influenced by urban sources, the mixing state was found to vary greatly, with nitrate and soot being the dominant species in Southern California, and sulfate and organic carbon in Northern California. Furthermore, mixing state varied temporally in Northern California, with soot becoming the prevalent particle type towards the end of the study as regional pollution levels increased. The results from these studies demonstrate that the majority of ambient carbonaceous particles in California are internally mixed and are heavily influenced by secondary species that are most prevalent in the particular region. Based on these findings, considerations of regionally dominant sources and secondary species, as well as temporal variations of aerosol physical and optical properties, will be required to obtain more accurate predictions of the climate impacts of aerosol in California.

scholarly journals Climate engineering and the ocean: effects on biogeochemistry and primary production

2017 ◽  
Author(s):  
Siv K. Lauvset ◽  
Jerry Tjiputra ◽  
Helene Muri
Keyword(s):  
Primary Production ◽  
Radiative Forcing ◽  
Large Scale ◽  
Stratospheric Aerosol ◽  
Climate Impacts ◽  
Environmental Drivers ◽  
Earth System ◽  
Climate Engineering ◽  
Mean Sea Surface ◽  
Radiation Management

Abstract. Here we use an Earth System Model with interactive biogeochemistry to project future ocean biogeochemistry impacts from large-scale deployment of three different radiation management (RM) climate engineering (also known as geoengineering) methods: stratospheric aerosol injection (SAI), marine sky brightening (MSB), and cirrus cloud thinning (CCT). We apply RM such that the change in radiative forcing in the RCP8.5 emission scenario is reduced to the change in radiative forcing in the RCP4.5 scenario. The resulting global mean sea surface temperatures in the RM experiments are comparable to those in RCP4.5, but there are regional differences. The forcing from MSB, for example, is applied over the oceans, so the cooling of the ocean is in some regions stronger for this method of RM than for the others. Changes in ocean primary production are much more variable, but SAI and MSB give a global decrease comparable to RCP4.5 (~ 6 % in 2100 relative to 1971–2000), while CCT give a much smaller global decrease of ~ 3 %. The spatially inhomogeneous changes in ocean primary production are partly linked to how the different RM methods affect the drivers of primary production (incoming radiation, temperature, availability of nutrients, and phytoplankton) in the model. The results of this work underscores the complexity of climate impacts on primary production, and highlights that changes are driven by an integrated effect of multiple environmental drivers, which all change in different ways. These results stress the uncertain changes to ocean productivity in the future and advocates caution at any deliberate attempt for large-scale perturbation of the Earth system.

scholarly journals Comparison of generalized non-data-driven lake and reservoir routing models for global-scale hydrologic forecasting of reservoir outflow at diurnal time steps

2020 ◽  
Vol 24 (5) ◽  
pp. 2711-2729 ◽  
Author(s):  
Joseph L. Gutenson ◽  
Ahmad A. Tavakoly ◽  
Mark D. Wahl ◽  
Michael L. Follum
Keyword(s):  
Large Scale ◽  
Spatial Scales ◽  
Model Performance ◽  
Global Scale ◽  
Army Corps ◽  
Time Step ◽  
Large Spatial Scale ◽  
Reservoir Routing ◽  
Routing Methods ◽  
Improved Model

Abstract. Large-scale hydrologic forecasts should account for attenuation through lakes and reservoirs when flow regulation is present. Globally generalized methods for approximating outflow are required but must contend with operational complexity and a dearth of information on dam characteristics at global spatial scales. There is currently no consensus on the best approach for approximating reservoir release rates in large spatial scale hydrologic forecasting, particularly at diurnal time steps. This research compares two parsimonious reservoir routing methods at daily steps: Döll et al. (2003) and Hanasaki et al. (2006). These reservoir routing methods have been previously implemented in large-scale hydrologic modeling applications and have been typically evaluated seasonally. These routing methods are compared across 60 reservoirs operated by the U.S. Army Corps of Engineers. The authors vary empirical coefficients for both reservoir routing methods as part of a sensitivity analysis. The method proposed by Döll et al. (2003) outperformed that presented by Hanasaki et al. (2006) at a daily time step and improved model skill over most run-of-the-river conditions. The temporal resolution of the model influences model performances. The optimal model coefficients varied across the reservoirs in this study and model performance fluctuates between wet years and dry years, and for different configurations such as dams in series. Overall, the method proposed by Döll et al. (2003) could enhance large-scale hydrologic forecasting, but can be subject to instability under certain conditions.

Paleoclimate science for the 21st century: a wishlist

2020 ◽  
Author(s):  
Kim M. Cobb
Keyword(s):  
Climate Change ◽  
Climate Impacts ◽  
Decision Makers ◽  
Earth System ◽  
Climate Trends ◽  
Multi Scale ◽  
The Earth ◽  
Key Stakeholders ◽  
Paleoclimate Records ◽  
Paleoclimate Data

<p>The study of past climate trends, variability, and extremes has yielded unique insights into Earth’s changing climate, yet paleoclimate science must overcome a number of key challenges to maximize its utility in a century defined by accelerating climate change. First, the paleoclimate archive itself is at grave risk, given that i) many records end in the late 20<sup>th</sup> century, and no concerted efforts exist to extend them to the present-day, and ii) many paleoclimate archives are disappearing under continued climate change and other forms of human disturbance. Second, many paleoclimate records are comprised of oxygen isotopes, yet the coordinated, multi-scale observational and modeling infrastructures required to unravel the mechanisms governing water isotope variability are as yet underdeveloped. Lastly, in part owing to the aforementioned deficiencies, paleoclimate data assimilation efforts remain fraught with large uncertainties, despite their promise in constraining many aspects of future climate impacts, including extreme events and hydrological trends and variability. Paleoclimate science for the 21<sup>st</sup> century requires deep investments in the full integration of paleoclimate data and approaches into frameworks for climate risk and hazard assessments. In that sense, paleoclimate scientists will continue to play a key role in the communication of climate change science to key stakeholders, including the general public. Their understanding of the Earth system also equips them to contribute valuable insights to teams comprised of researchers, practitioners, and  decision-makers charged with leveraging science to inform solutions, in service to society.</p>

Derivation of Optical Properties of Carbonaceous Aerosols by Monochromated Electron Energy-Loss Spectroscopy

2014 ◽  
Vol 20 (3) ◽  
pp. 748-759 ◽  
Author(s):  
Jiangtao Zhu ◽  
Peter A. Crozier ◽  
Peter Ercius ◽  
James R. Anderson
Keyword(s):  
Optical Properties ◽  
Energy Loss ◽  
Electron Energy ◽  
Amorphous Carbon ◽  
Electron Energy Loss Spectroscopy ◽  
Radiative Forcing ◽  
Accurate Determination ◽  
Carbonaceous Aerosols ◽  
Carbonaceous Particles ◽  
Electron Energy Loss

AbstractMonochromated electron energy-loss spectroscopy (EELS) is employed to determine the optical properties of carbonaceous aerosols from the infrared to the ultraviolet region of the spectrum. It is essential to determine their optical properties to understand their accurate contribution to radiative forcing for climate change. The influence of surface and interface plasmon effects on the accuracy of dielectric data determined from EELS is discussed. Our measurements show that the standard thin film formulation of Kramers−Kronig analysis can be employed to make accurate determination of the dielectric function for carbonaceous particles down to about 40 nm in size. The complex refractive indices of graphitic and amorphous carbon spherules found in the atmosphere were determined over the wavelength range 200–1,200 nm. The graphitic carbon was strongly absorbing black carbon, whereas the amorphous carbon shows a more weakly absorbing brown carbon profile. The EELS approach provides an important tool for exploring the variation in optical properties of atmospheric carbon.

Costing the Earth: A Numbers Game or a Moral Imperative?

2013 ◽  
Vol 5 (4) ◽  
pp. 378-380 ◽  
Author(s):  
Gerard Roe
Keyword(s):  
Climate Change ◽  
Regional Climate ◽  
Relative Weight ◽  
Global Scale ◽  
Climate Impacts ◽  
Economic Consequences ◽  
Economic Costs ◽  
Policy Makers ◽  
The Earth ◽  
Moral Arguments

Abstract It is a simple truism that public policy must be guided by an objective analysis of the physical and economic consequences of climate change. It is equally true that policy making is an inherently value-laden endeavor. While these two threads are interconnected, the relative weight given to each depends on the certainty that the technical analyses can deliver. For climate change, the envelope of uncertainty is best understood at the global scale, and there are some well known and formidable challenges to reducing it. This uncertainty must in turn be compounded with much more poorly constrained uncertainties in regional climate, climate impacts, and future economic costs. The case can be made that technical analyses have reached the point of diminishing returns. Should meaningful action on climate change await greater analytical certainty? This paper argues that policy makers should give greater weight to moral arguments, in no small part because that is where the heart of the debate really lies.

scholarly journals The effect of optically thin cirrus clouds on solar radiation in Camagüey, Cuba

2011 ◽  
Vol 11 (3) ◽  
pp. 8777-8799
Author(s):  
B. Barja ◽  
J. C. Antuña
Keyword(s):  
Solar Radiation ◽  
Radiative Forcing ◽  
Near Infrared ◽  
Local Heating ◽  
Spectral Band ◽  
Solar Spectrum ◽  
Cirrus Clouds ◽  
Radiation Budget ◽  
Earth System ◽  
The Earth

Abstract. Cirrus clouds play a key role in the radiation budget of the Earth system. They are an important aspect in the climate system, as they interact with the atmospheric radiation field. They control both the solar radiation that reaches the Earth surface and the longwave radiation that leaves the Earth system. The feedback produced by cirrus clouds in climate is not well understood. Therefore it is necessary to improve the understanding and characterization of the radiative forcing of cirrus clouds. We analyze the effect of optically thin cirrus clouds characterized with the lidar technique in Camagüey, Cuba, on solar radiation, by numerical simulation. Nature and amplitude of the effect of cirrus clouds on solar radiation is evaluated. Cirrus clouds have a cooling effect in the solar spectrum at the Top of the Atmosphere (TOA) and at the surface (SFC). The daily mean value of solar cirrus cloud radiative forcing (SCRF) has an average value of −9.1 W m−2 at TOA and −5.6 W m−2 at SFC. The cirrus clouds also have a local heating effect on the atmospheric layer where they are located. Cirrus clouds have mean daily values of heating rates of 0.63 K day−1 with a range between 0.35 K day−1 and 1.24 K day−1. The principal effect is in the near infrared spectral band of the solar spectrum. There is a linear relation between SCRF and cirrus clouds optical depth (COD), with −30 W m−2 COD−1 and −26 W m−2 COD−1, values for the slopes of the fits at the TOA and SFC, respectively in the broadband solar spectrum. Also there is a relation between the solar zenith angle and cirrus clouds radiative forcing displayed in the diurnal cycle.

scholarly journals Biogeochemical Consequences of Ocean Acidification and Feedbacks to the Earth System

2011 ◽  
Author(s):  
Marion Gehlen ◽  
Nicolas Gruber
Keyword(s):  
Ocean Acidification ◽  
Radiative Forcing ◽  
Biogeochemical Cycles ◽  
Biological Pump ◽  
Earth System ◽  
Carbonate Chemistry ◽  
Emission Pathway ◽  
The Earth ◽  
Indirect Impacts ◽  
Active Substances

By the year 2008, the ocean had taken up approximately 140 Gt carbon corresponding to about a third of the total anthropogenic CO2 emitted to the atmosphere since the onset of industrialization (Khatiwala et al. 2009 ). As the weak acid CO2 invades the ocean, it triggers changes in ocean carbonate chemistry and ocean pH (see Chapter 1). The pH of modern ocean surface waters is already 0.1 units lower than in pre-industrial times and a decrease by 0.4 units is projected by the year 2100 in response to a business-as- usual emission pathway (Caldeira and Wickett 2003). These changes in ocean carbonate chemistry are likely to affect major ocean biogeochemical cycles, either through direct pH effects or indirect impacts on the structure and functioning of marine ecosystems. This chapter addresses the potential biogeochemical consequences of ocean acidification and associated feedbacks to the earth system, with focus on the alteration of element fluxes at the scale of the global ocean. The view taken here is on how the different effects interact and ultimately alter the atmospheric concentration of radiatively active substances, i.e. primarily greenhouse gases such as CO2 and nitrous oxide (N2O). Changes in carbonate chemistry have the potential for interacting with ocean biogeochemical cycles and creating feedbacks to climate in a myriad of ways (Box 12.1). In order to provide some structure to the discussion, direct and indirect feedbacks of ocean acidification on the earth system are distinguished. Direct feedbacks are those which directly affect radiative forcing in the atmosphere by altering the air–sea flux of radiatively active substances. Indirect feedbacks are those that first alter a biogeochemical process in the ocean, and through this change then affect the air–sea flux and ultimately the radiative forcing in the atmosphere. For example, when ocean acidification alters the production and export of organic matter by the biological pump, then this is an indirect feedback. This is because a change in the biological pump alters radiative forcing in the atmosphere indirectly by first changing the nearsurface concentrations of dissolved inorganic carbon and total alkalinity.

Reduced effective radiative forcing from cloud-aerosol interactions with improved modelling of early aerosol growth in an Earth System Model

2021 ◽  
Author(s):  
Sara Marie Blichner ◽  
Moa Kristina Sporre ◽  
Terje Koren Berntsen
Keyword(s):  
Radiative Forcing ◽  
Particle Growth ◽  
Particle Formation ◽  
Climate Impacts ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
New Particle Formation ◽  
Secondary Aerosol ◽  
Effective Radiative Forcing

<p>Cloud-aerosol interactions are responsible for much of the uncertainty in forcing estimates from pre-industrial times and thus also climate sensitivity and future projections. Maybe the most important factor in this is our lack of knowledge about pre-industrial aerosols, their sources and their ability to act as cloud condensation nuclei (CCN). The number of CCN is highly dependent on secondary aerosol formation and in particular how much of this secondary aerosol mass that goes to new particle formation (NPF) and early particle growth, versus growing already large particles even larger. <br>Earth system models which seek to model this, face a challenge because we need to represent processes at a very fine scale (nanometers) to a sufficient accuracy, while simultaneously keeping computational costs low. A common approach is to use log-normal modes to represent the sizedistribution, while more computationally expensive sectional schemes are considered closer to first principles. </p><p>In this study, we investigate the effect of a newly developed scheme for early particle growth on the effective radiative forcing from cloud-aerosol interactions (ERF<sub>aci</sub>)  in the Norwegian Earth System Model v2 (NorESMv2). The new scheme, referred to as OsloAeroSec, presented in  Blichner et al. (2020), combines a sectional scheme for the growth of the smallest particles (5 - 39.6 nm), with the original semi-modal aerosol scheme which would simply parameterize the growth up to the smallest mode with Lehtinen et al. (2007). This was shown to to improve the representation of CCN relevant particle concentrations, when compared to measurement data.  </p><p>We find that ERF<sub>aci</sub> is weakened by approximately 10 % with the new scheme (from -1.29  to -1.16 Wm<sup>-2</sup>). The weakening originates from OsloAeroSec (the new scheme) reducing particle formation in regions with high aerosol concentrations while increasing it in very pristine regions. We find, perhaps surprisingly, that an important factor for the overall forcing, is that  NPF inhibits aerosol activation into cloud droplets in high-aerosol-concentration regions, while the opposite is true in pristine regions. <br>This is because the NPF particles act as a condensation sink, and if they cannot activate directly themselves, they may reduce the growth of the larger particles which would otherwise activate. <br>Furthermore, we find that the increase in particle hygroscopicity with present day emissions of sulphate pre-cursors, decreases the size of the activated particles, and thus makes NPF particles more relevant for cloud droplet activation. </p><p><strong>References: </strong></p><p>Lehtinen, Kari E. J., Miikka Dal Maso, Markku Kulmala, and Veli-Matti Kerminen. “Estimating Nucleation Rates from Apparent Particle Formation Rates and Vice Versa: Revised Formulation of the Kerminen–Kulmala Equation.” Journal of Aerosol Science (2007): https://doi.org/10.1016/j.jaerosci.2007.06.009.</p><p>Blichner, Sara M., Moa K. Sporre, Risto Makkonen, and Terje K. Berntsen. “Implementing a sectional scheme for early aerosol growth from new particle formation in the Norwegian Earth System Model v2: comparison to observations and climate impacts.” Geoscientific Model Development Discussions (2020): https://doi.org/10.5194/gmd-2020-357</p>

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