scholarly journals Easy Volcanic Aerosol (EVA v1.0): An idealized forcing generator for climate simulations

2016 ◽  
Author(s):  
Matthew Toohey ◽  
Bjorn Stevens ◽  
Hauke Schmidt ◽  
Claudia Timmreck
Keyword(s):  
Time Scale ◽  
Climate Models ◽  
Single Scattering ◽  
Stratospheric Aerosol ◽  
Asymmetry Factor ◽  
Volcanic Aerosol ◽  
Climate Simulations ◽  
Simple Scaling ◽  
Millennial Time Scale ◽  
Aerosol Properties

Abstract. The Easy Volcanic Aerosol (EVA) forcing generator produces stratospheric aerosol optical properties as a function of time, latitude, height and wavelength for a given input list of volcanic eruption attributes. EVA is based on a parameterized three-box model of stratospheric transport, and simple scaling relationships used to derive mid-visible (550 nm) aerosol optical depth and aerosol effective radius from stratospheric sulfate mass. Pre-calculated look up tables computed from Mie theory are used to produce wavelength dependent aerosol extinction, single scattering albedo and scattering asymmetry factor values. The structural form of EVA, and the tuning of its parameters, are chosen to produce best agreement with the satellite-based reconstruction of stratospheric aerosol properties following the 1991 Pinatubo eruption, and with prior millennial-time scale forcing reconstructions including the 1815 eruption of Tambora. EVA can be used to produce volcanic forcing for climate models which is based on recent observations and physical understanding, but internally self-consistent over any time-scale of choice. In addition, EVA is constructed so as to allow for easy modification of different aspects of aerosol properties, in order to be used in model experiments to help advance understanding of what aspects of the volcanic aerosol are important for the climate system.

scholarly journals Easy Volcanic Aerosol (EVA v1.0): an idealized forcing generator for climate simulations

2016 ◽  
Vol 9 (11) ◽  
pp. 4049-4070 ◽  
Author(s):  
Matthew Toohey ◽  
Bjorn Stevens ◽  
Hauke Schmidt ◽  
Claudia Timmreck
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Volcanic Eruptions ◽  
Single Scattering ◽  
Stratospheric Aerosol ◽  
Asymmetry Factor ◽  
Volcanic Aerosol ◽  
Climate Model Simulations ◽  
Earth’S Climate ◽  
Aerosol Properties

Abstract. Stratospheric sulfate aerosols from volcanic eruptions have a significant impact on the Earth's climate. To include the effects of volcanic eruptions in climate model simulations, the Easy Volcanic Aerosol (EVA) forcing generator provides stratospheric aerosol optical properties as a function of time, latitude, height, and wavelength for a given input list of volcanic eruption attributes. EVA is based on a parameterized three-box model of stratospheric transport and simple scaling relationships used to derive mid-visible (550 nm) aerosol optical depth and aerosol effective radius from stratospheric sulfate mass. Precalculated look-up tables computed from Mie theory are used to produce wavelength-dependent aerosol extinction, single scattering albedo, and scattering asymmetry factor values. The structural form of EVA and the tuning of its parameters are chosen to produce best agreement with the satellite-based reconstruction of stratospheric aerosol properties following the 1991 Pinatubo eruption, and with prior millennial-timescale forcing reconstructions, including the 1815 eruption of Tambora. EVA can be used to produce volcanic forcing for climate models which is based on recent observations and physical understanding but internally self-consistent over any timescale of choice. In addition, EVA is constructed so as to allow for easy modification of different aspects of aerosol properties, in order to be used in model experiments to help advance understanding of what aspects of the volcanic aerosol are important for the climate system.

scholarly journals Impact of long-range transport over the Atlantic Ocean on Saharan dust optical and microphysical properties

2017 ◽  
Author(s):  
Cristian Velasco-Merino ◽  
David Mateos ◽  
Carlos Toledano ◽  
Joseph M. Prospero ◽  
Jack Molinie ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Size Distribution ◽  
Mineral Dust ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
West African ◽  
Asymmetry Factor ◽  
Caribbean Basin ◽  
Air Mass ◽  
Aerosol Properties

Abstract. Mineral dust aerosol can be a major driver of aerosol climatology in regions distant from the sources. This study addresses the change of columnar aerosol properties when mineral dust arrives to the Caribbean Basin after transport from Africa over the Atlantic Ocean. We use data from NASA Aerosol Robotic Network (AERONET) sites in five Caribbean and two West African sites to characterize changes in aerosol properties: aerosol optical depth, size distribution, single scattering albedo, and refractive indexes. After obtaining local aerosol climatology in each area, the air mass connections between West Africa and Caribbean Basin have been investigated by means of air mass back trajectories. Over the period 1996–2014 we identify 3174 connection days, on average, 167 connection days per year. Among these, 1162 pairs of data present aerosol data in Caribbean sites with corresponding aerosol observations in Western Africa sites ~5–7 days before. Of these 1162 days, 484 meet the criteria to be characterized as mineral dust outbreaks. Based on these days we observe the following changes in aerosol-related properties in transiting the Atlantic: AOD decreases about 0.16 or −30 %; the volume particle size distribution shape shows no changes; single scattering albedo, refractive indexes, and asymmetry factor remain unchanged; the difference in the effective radius in West African area with respect to Caribbean Basin is between 0 and +0.3 µm; and half of the analyzed cases present predominance of non-spherical particles in both areas.

Recovered measurements of the 1960s stratospheric aerosol layer for new constraints for volcanic forcing in the years after 1963 Agung

2020 ◽  
Author(s):  
Graham Mann ◽  
Juan Carlos Antuna Marrero ◽  
Amanda Maycock ◽  
Christine McKenna ◽  
Sarah Shallcross ◽  
...  
Keyword(s):  
Aerosol Particle ◽  
Climate Models ◽  
Stratospheric Aerosol ◽  
Volcanic Plume ◽  
Aerosol Layer ◽  
Volcanic Aerosol ◽  
Surface Cooling ◽  
Aerosol Model ◽  
Volcanic Forcing ◽  
The 1960S

<p>The WCRP-SPARC initiative on stratospheric sulphur (SSiRC) has begun a new activity to recover past observational datasets of the stratospheric aerosol layer.</p><p>The data rescue activity aims to provide additional constraints for volcanic impacts on climate and is organised into three time-periods:</p><ol><li>The quiescent period prior to the major eruption 1963 Agung eruption,</li> <li>The period of strong volcanic activity during 1963-1969,</li> <li>The Jul-Dec 1991 period after Pinatubo when the SAGE-II signal was saturated.</li> </ol><p>A new page within the SSiRC website gives further information on the datasets within this activity ( http://www.sparc-ssirc.org  --> Activities --> Data Rescue).</p><p>In this presentation, we explain the 1963-1969 component of the data rescue, and compare the CMIP5 and CMIP6 volcanic aerosol datasets during this period, post-Agung interactive stratospheric aerosol model simulations and a preliminary analysis of 15-year global-mean surface temperature trends from CMIP6 historical integrations for 1950-1980.</p><p>The 1960s was a strongly volcanically active decade, with the major 1963 Agung eruption and tropical stratosphere-injecting eruptions in 1965 (Taal), 1966 (Awu) and 1968 (Fernandina) generating a prolonged period of strong natural surface cooling.</p><p>Less than a year after the Agung eruption, the first in-situ measurements of a major volcanic aerosol cloud were made with dust-sondes from Minneapolis measuring aerosol particle concentrations with 10 soundings between 1963 and 1965 (6 in 1963-4).</p><p>Global surveys with the U-2 aircraft were equipped with impactors to measure stratospheric aerosol particle size distribution and composition, for example detecting the presence of volcanic ash within the Agung volcanic plume.</p><p>Early ground-based active remote sensing measurements (lidar, searchlight) also measured the vertical profile of the Agung-enhanced stratospheric aerosol layer.</p><p>The main purpose of the SSiRC data rescue is to provide constraints for interactive stratospheric aerosol models, aligning with the ISA-MIP activity, which could potentially lead to new volcanic forcing datasets for climate models, ultimately thereby aiming to improve attribution of anthropogenic change and future projections.</p>

scholarly journals Comparing multiple model-derived aerosol optical properties to collocated ground-based and satellite measurements

2016 ◽  
Author(s):  
Ilissa B. Ocko ◽  
Paul A. Ginoux
Keyword(s):  
Climate Models ◽  
Climate Modeling ◽  
Global Climate ◽  
Measurement Techniques ◽  
Single Scattering ◽  
Global Climate Models ◽  
Multiple Model ◽  
Anthropogenic Aerosols ◽  
Earth’S Climate ◽  
Aerosol Properties

Abstract. Anthropogenic aerosols are a key factor governing Earth’s climate, and play a central role in human-caused climate change. However, because of aerosols’ complex physical, optical, and dynamical properties, aerosols are one of the most uncertain aspects of climate modeling. Fortunately, aerosol measurement networks over the past few decades have led to the establishment of long-term observations for numerous locations worldwide. Further, the availability of datasets from several different measurement techniques (such as ground-based and satellite instruments) can help scientists increasingly improve modeling efforts. This study explores the value of evaluating several model-simulated aerosol properties with data from collocated instruments. We compare optical depth (total, scattering, and absorption), single scattering albedo, Ångström exponent, and extinction vertical profiles in two prominent global climate models to seasonal observations from collocated instruments (AERONET and CALIOP) at seven polluted and biomass burning regions worldwide. We find that models may accurately reproduce one variable while totally failing at another; data from collocated instruments can reveal underlying aerosol-governing physics; column properties may wash out important vertical distinctions; and "improved" models does not mean all aspects are improved. We conclude that it is important to make use of all available data (parameters and instruments) when evaluating aerosol properties derived by models.

scholarly journals Impact of Aerosol on the Estimation Accuracy of Solar Radiation

2018 ◽  
Vol 60 (1) ◽  
pp. 97-103
Author(s):  
Calinoiu Delia-Gabriela ◽  
Paulescu Marius
Keyword(s):  
Solar Irradiance ◽  
Single Scattering ◽  
Empirical Models ◽  
Parametric Models ◽  
Surface Radiation ◽  
Estimation Accuracy ◽  
Asymmetry Factor ◽  
Clear Sky ◽  
Sky Conditions ◽  
Aerosol Properties

AbstractThe paper is focused on the solar irradiance estimation in clear-sky conditions and an aerosol-loaded atmosphere. Two parametric models developed by our group and three empirical models are tested. The estimates of the parametric models are based on three atmospheric parameters (ozone, nitrogen dioxide and water vapor column content) and the aerosol properties quantified by means of several specific parameters (Ångström turbidity coefficient, single scattering albedo, asymmetry factor). The empirical models contain no inputs for aerosol properties. Data collected from 10 stations were used to test the models. The inputs for the parametric models were retrieved from Aerosol Robotic Network - AERONET. Global and diffuse solar irradiance data at high-quality standards were retrieved from the Baseline Surface Radiation Network BSRN. A comparative analysis of the models’ accuracy in estimating clear-sky solar irradiance is discussed from the perspective of aerosol proprieties.

Aerosol Direct Radiative Effect Sensitivity Analysis

2020 ◽  
Vol 33 (14) ◽  
pp. 6119-6139 ◽  
Author(s):  
Tyler J. Thorsen ◽  
Richard A. Ferrare ◽  
Seiji Kato ◽  
David M. Winker
Keyword(s):  
Near Infrared ◽  
Single Scattering ◽  
Reanalysis Data ◽  
Asymmetry Factor ◽  
Radiative Effect ◽  
Cloud Optical Depth ◽  
Clear Sky ◽  
Crucial Component ◽  
Aerosol Scattering ◽  
Aerosol Properties

AbstractBoth to reconcile the large range in satellite-based estimates of the aerosol direct radiative effect (DRE) and to optimize the design of future observing systems, this study builds a framework for assessing aerosol DRE uncertainty. Shortwave aerosol DRE radiative kernels (Jacobians) were derived using the MERRA-2 reanalysis data. These radiative kernels give the differential response of the aerosol DRE to perturbations in the aerosol extinction coefficient, aerosol single-scattering albedo, aerosol asymmetry factor, surface albedo, cloud fraction, and cloud optical depth. This comprehensive set of kernels provides a convenient way to consistently and accurately assess the aerosol DRE uncertainties that result from observational or model-based uncertainties. The aerosol DRE kernels were used to test the effect of simplifying the full vertical profile of aerosol scattering properties into column-integrated quantities. This analysis showed that, although the clear-sky aerosol DRE can be had fairly accurately, more significant errors occur for the all-sky DRE. The sensitivity in determining the broadband spectral dependencies of the aerosol scattering properties directly from a limited set of wavelengths was quantified. These spectral dependencies can be reasonably constrained using column-integrated aerosol scattering properties in the midvisible and near-infrared wavelengths. Separating the aerosol DRE and its kernels by scene type shows that accurate aerosol properties in the clear sky are the most crucial component of the global aerosol DRE. In cloudy skies, determining aerosol properties in the presence of optically thin cloud is more radiatively important than doing so when optically thick cloud is present.

scholarly journals Impact of Snow Grain Shape and Black Carbon–Snow Internal Mixing on Snow Optical Properties: Parameterizations for Climate Models

2017 ◽  
Vol 30 (24) ◽  
pp. 10019-10036 ◽  
Author(s):  
Cenlin He ◽  
Yoshi Takano ◽  
Kuo-Nan Liou ◽  
Ping Yang ◽  
Qinbin Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Optical Properties ◽  
Black Carbon ◽  
Size Effects ◽  
Climate Models ◽  
Grain Shape ◽  
Single Scattering ◽  
Asymmetry Factor ◽  
Grain Sizes ◽  
Internal Mixing

A set of parameterizations is developed for spectral single-scattering properties of clean and black carbon (BC)-contaminated snow based on geometric-optics surface wave (GOS) computations, which explicitly resolves BC–snow internal mixing and various snow grain shapes. GOS calculations show that, compared with nonspherical grains, volume-equivalent snow spheres show up to 20% larger asymmetry factors and hence stronger forward scattering, particularly at wavelengths <1 μm. In contrast, snow grain sizes have a rather small impact on the asymmetry factor at wavelengths <1 μm, whereas size effects are important at longer wavelengths. The snow asymmetry factor is parameterized as a function of effective size, aspect ratio, and shape factor and shows excellent agreement with GOS calculations. According to GOS calculations, the single-scattering coalbedo of pure snow is predominantly affected by grain sizes, rather than grain shapes, with higher values for larger grains. The snow single-scattering coalbedo is parameterized in terms of the effective size that combines shape and size effects, with an accuracy of >99%. Based on GOS calculations, BC–snow internal mixing enhances the snow single-scattering coalbedo at wavelengths <1 μm, but it does not alter the snow asymmetry factor. The BC-induced enhancement ratio of snow single-scattering coalbedo, independent of snow grain size and shape, is parameterized as a function of BC concentration with an accuracy of >99%. Overall, in addition to snow grain size, both BC–snow internal mixing and snow grain shape play critical roles in quantifying BC effects on snow optical properties. The present parameterizations can be conveniently applied to snow, land surface, and climate models including snowpack radiative transfer processes.

scholarly journals Differences in the Evolution of Pyrocumulonimbus and Volcanic Stratospheric Plumes as Observed by CATS and CALIOP Space-Based Lidars

Atmosphere ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1035
Author(s):  
Kenneth Christian ◽  
John Yorks ◽  
Sampa Das
Keyword(s):  
Pacific Northwest ◽  
Stratospheric Aerosol ◽  
Volcanic Aerosol ◽  
Volcanic Plumes ◽  
Size And Shape ◽  
Altitude Dependence ◽  
Volcanic Events ◽  
Spatial Propagation ◽  
Depolarization Ratios

Recent fire seasons have featured volcanic-sized injections of smoke aerosols into the stratosphere where they persist for many months. Unfortunately, the aging and transport of these aerosols are not well understood. Using space-based lidar, the vertical and spatial propagation of these aerosols can be tracked and inferences can be made as to their size and shape. In this study, space-based CATS and CALIOP lidar were used to track the evolution of the stratospheric aerosol plumes resulting from the 2019–2020 Australian bushfire and 2017 Pacific Northwest pyrocumulonimbus events and were compared to two volcanic events: Calbuco (2015) and Puyehue (2011). The pyrocumulonimbus and volcanic aerosol plumes evolved distinctly, with pyrocumulonimbus plumes rising upwards of 10 km after injection to altitudes of 30 km or more, compared to small to modest altitude increases in the volcanic plumes. We also show that layer-integrated depolarization ratios in these large pyrocumulonimbus plumes have a strong altitude dependence with more irregularly shaped particles in the higher altitude plumes, unlike the volcanic events studied.

Aerosol Properties and Processes: A Path from Field and Laboratory Measurements to Global Climate Models

2007 ◽  
Vol 88 (7) ◽  
pp. 1059-1084 ◽  
Author(s):  
Steven J. Ghan ◽  
Stephen E. Schwartz
Keyword(s):  
Climate Models ◽  
Global Climate ◽  
Field Measurements ◽  
Substantial Improvement ◽  
Global Climate Models ◽  
Department Of Energy ◽  
Lower Atmosphere ◽  
Laboratory Measurements ◽  
Successive Generations ◽  
Aerosol Properties

Aerosol particles in the lower atmosphere exert a substantial influence on climate and climate change through a variety of complex mechanisms. Consequently, there is a need to represent these influences in global climate models, and models have begun to include representations of these influences. However, the present treatment of aerosols in global climate models is highly simplified, omitting many processes and feedbacks that are thought to be climatically important. Thus, there is need for substantial improvement. Here we describe the strategy of the U.S. Department of Energy for improving representation of the properties, processes, and effects of tropospheric aerosols in global climate models. The strategy begins with a foundation of field and laboratory measurements that provide the basis for modules describing specific aerosol properties and processes. These modules are then integrated into regional aerosol models, which are evaluated by comparison with field measurements. Issues of scale are then addressed so that the modules can be applied to global aerosol models, which are evaluated by comparison with satellite retrievals and other observations. Finally, the validated set of modules is applied in global climate models for multicentury simulations. This strategy is expected to be applied to successive generations of global climate models.

scholarly journals Comparing multiple model-derived aerosol optical properties to spatially collocated ground-based and satellite measurements

2017 ◽  
Vol 17 (7) ◽  
pp. 4451-4475 ◽  
Author(s):  
Ilissa B. Ocko ◽  
Paul A. Ginoux
Keyword(s):  
Climate Models ◽  
Climate Modeling ◽  
Global Climate ◽  
Measurement Techniques ◽  
Global Climate Models ◽  
Orthogonal Polarization ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Multiple Model ◽  
Anthropogenic Aerosols ◽  
Aerosol Properties

Abstract. Anthropogenic aerosols are a key factor governing Earth's climate and play a central role in human-caused climate change. However, because of aerosols' complex physical, optical, and dynamical properties, aerosols are one of the most uncertain aspects of climate modeling. Fortunately, aerosol measurement networks over the past few decades have led to the establishment of long-term observations for numerous locations worldwide. Further, the availability of datasets from several different measurement techniques (such as ground-based and satellite instruments) can help scientists increasingly improve modeling efforts. This study explores the value of evaluating several model-simulated aerosol properties with data from spatially collocated instruments. We compare aerosol optical depth (AOD; total, scattering, and absorption), single-scattering albedo (SSA), Ångström exponent (α), and extinction vertical profiles in two prominent global climate models (Geophysical Fluid Dynamics Laboratory, GFDL, CM2.1 and CM3) to seasonal observations from collocated instruments (AErosol RObotic NETwork, AERONET, and Cloud–Aerosol Lidar with Orthogonal Polarization, CALIOP) at seven polluted and biomass burning regions worldwide. We find that a multi-parameter evaluation provides key insights on model biases, data from collocated instruments can reveal underlying aerosol-governing physics, column properties wash out important vertical distinctions, and improved models does not mean all aspects are improved. We conclude that it is important to make use of all available data (parameters and instruments) when evaluating aerosol properties derived by models.

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