scholarly journals General overview: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) – integrating aerosol research from nano to global scales

2011 ◽  
Vol 11 (6) ◽  
pp. 17941-18160 ◽  
Author(s):  
M. Kulmala ◽  
A. Asmi ◽  
H. K. Lappalainen ◽  
U. Baltensperger ◽  
J.-L. Brenguier ◽  
...  
Keyword(s):  
Air Quality ◽  
Radiative Forcing ◽  
Climate Models ◽  
Global Climate ◽  
Global Scale ◽  
Global Climate Models ◽  
Modeling Tools ◽  
Emissions Inventory ◽  
Airborne Measurements ◽  
Aerosol Cloud

Abstract. In this paper we describe and summarize the main achievements of the European Aerosol Cloud Climate and Air Quality Interactions project (EUCAARI). EUCAARI started on 1 January 2007 and ended on 31 December 2010 leaving a rich legacy including: (a) a comprehensive database with a year of observations of the physical, chemical and optical properties of aerosol particles over Europe, (b) the first comprehensive aerosol measurements in four developing countries, (c) a database of airborne measurements of aerosols and clouds over Europe during May 2008, (d) comprehensive modeling tools to study aerosol processes fron nano to global scale and their effects on climate and air quality. In addition a new Pan-European aerosol emissions inventory was developed and evaluated, a new cluster spectrometer was built and tested in the field and several new aerosol parameterizations and computations modules for chemical transport and global climate models were developed and evaluated. This work enabled EUCAARI to improve our understanding of aerosol radiative forcing and air quality-climate interactions. The EUCAARI results can be utilized in European and global environmental policy to assess the aerosol impacts and the corresponding abatement strategies.

scholarly journals General overview: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) – integrating aerosol research from nano to global scales

2011 ◽  
Vol 11 (24) ◽  
pp. 13061-13143 ◽  
Author(s):  
M. Kulmala ◽  
A. Asmi ◽  
H. K. Lappalainen ◽  
U. Baltensperger ◽  
J.-L. Brenguier ◽  
...  
Keyword(s):  
Air Quality ◽  
Radiative Forcing ◽  
Climate Models ◽  
Global Climate ◽  
Global Scale ◽  
Global Climate Models ◽  
Modeling Tools ◽  
Emissions Inventory ◽  
Airborne Measurements ◽  
Aerosol Cloud

Abstract. In this paper we describe and summarize the main achievements of the European Aerosol Cloud Climate and Air Quality Interactions project (EUCAARI). EUCAARI started on 1 January 2007 and ended on 31 December 2010 leaving a rich legacy including: (a) a comprehensive database with a year of observations of the physical, chemical and optical properties of aerosol particles over Europe, (b) comprehensive aerosol measurements in four developing countries, (c) a database of airborne measurements of aerosols and clouds over Europe during May 2008, (d) comprehensive modeling tools to study aerosol processes fron nano to global scale and their effects on climate and air quality. In addition a new Pan-European aerosol emissions inventory was developed and evaluated, a new cluster spectrometer was built and tested in the field and several new aerosol parameterizations and computations modules for chemical transport and global climate models were developed and evaluated. These achievements and related studies have substantially improved our understanding and reduced the uncertainties of aerosol radiative forcing and air quality-climate interactions. The EUCAARI results can be utilized in European and global environmental policy to assess the aerosol impacts and the corresponding abatement strategies.

scholarly journals Machine learning uncovers aerosol size information from chemistry and meteorology to quantify potential cloud-forming particles

2021 ◽  
Author(s):  
Arshad Nair ◽  
Fangqun Yu ◽  
Pedro Campuzano Jost ◽  
Paul DeMott ◽  
Ezra Levin ◽  
...  
Keyword(s):  
Climate Change ◽  
Machine Learning ◽  
Radiative Forcing ◽  
Climate Models ◽  
Cloud Condensation Nuclei ◽  
Global Climate Models ◽  
Aerosol Composition ◽  
Airborne Measurements ◽  
Aerosol Cloud ◽  
Aerosol Cloud Interactions

Abstract Cloud condensation nuclei (CCN) are mediators of aerosol–cloud interactions, which contribute to the largest uncertainty in climate change prediction. Here, we present a machine learning/artificial intelligence model that quantifies CCN from variables of aerosol composition, atmospheric trace gases, and meteorology. Comprehensive multi-campaign airborne measurements, covering varied physicochemical regimes in the troposphere, confirm the validity of and help probe the inner workings of this machine learning model: revealing for the first time that different ranges of atmospheric aerosol composition and mass correspond to distinct aerosol number size distributions. Machine learning extracts this information, important for accurate quantification of CCN, additionally from both chemistry and meteorology. This can provide a physicochemically explainable, computationally efficient, robust machine learning pathway in global climate models that only resolve aerosol composition; potentially mitigating the uncertainty of effective radiative forcing due to aerosol–cloud interactions (ERFaci) and improving confidence in assessment of anthropogenic contributions and climate change projections.

A synthesis of observations of aerosol-cloud interactions over the pristine, biologically active Southern Ocean and their implications for global climate model predictions

2021 ◽  
Author(s):  
Isabel L. McCoy ◽  
Daniel T. McCoy ◽  
Robert Wood ◽  
Christopher S. Bretherton ◽  
Leighton Regayre ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Radiative Forcing ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Model ◽  
Global Climate Models ◽  
Biologically Active ◽  
Aerosol Cloud ◽  
Aerosol Cloud Interactions ◽  
Industrial State

<div> <p>The change in planetary albedo due to aerosol-cloud interactions (aci) during the industrial era is the leading source of uncertainty in inferring Earth's climate sensitivity to increased greenhouse gases from the historical record. Examining pristine environments such as the Southern Ocean (SO) helps us to understand the pre-industrial state and constrain the change in cloud brightness over the industrial period associated with aci. This study presents two methods of utilizing observations of pristine environments to examine climate models and our understanding of the pre-industrial state.</p> </div><div> <p>First, cloud droplet number concentration (<em>N<sub>d</sub></em>) is used as an indicator of aci. Global climate models (GCMs) show that the hemispheric contrast in liquid cloud <em>N<sub>d</sub></em> between the pristine SO and the polluted Northern Hemisphere observed in the present-day can be used<strong> </strong>as a proxy for the increase in <em>N<sub>d</sub></em> from the pre-industrial. A hemispheric difference constraint developed from MODIS satellite observations indicates that pre-industrial <em>N<sub>d</sub></em> may have been higher than previously thought and provides an estimate of radiative forcing associated with aci between -1.2 and -0.6 Wm<sup>-2</sup>. Comparisons with MODIS <em>N<sub>d  </sub></em>highlight significant GCM discrepancies in pristine, biologically active regions.</p> </div><div> <p>Second, aerosol and cloud microphysical observations from a recent SO aircraft campaign are used to identify two potentially important mechanisms that are incomplete or missing in GCMs: i) production of new aerosol particles through synoptic uplift, and ii) buffering of <em>N<sub>d</sub></em> against precipitation removal by small, Aitken mode aerosols entrained from the free troposphere. The latter may significantly contribute to the high, summertime SO <em>N<sub>d</sub></em> levels which persist despite precipitation depletion associated with mid-latitude storm systems. Observational comparisons with nudged Community Atmosphere Model version 6 (CAM6) hindcasts show low-biased SO <em>N<sub>d  </sub></em>is linked to under-production of free-tropospheric Aitken aerosol which drives low-biases in cloud condensation nuclei number and likely discrepancies in composition. These results have important implications for the ability of current GCMs to capture aci in pristine environments.</p> </div>

scholarly journals Eastern Pacific Emitted Aerosol Cloud Experiment

2013 ◽  
Vol 94 (5) ◽  
pp. 709-729 ◽  
Author(s):  
Lynn M. Russell ◽  
Armin Sorooshian ◽  
John H. Seinfeld ◽  
Bruce A. Albrecht ◽  
Athanasios Nenes ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Climate Models ◽  
Climate Model ◽  
Global Climate ◽  
Cloud Microphysics ◽  
Global Climate Models ◽  
Eastern Pacific ◽  
Mass Composition ◽  
Aerosol Cloud ◽  
Embedded Modeling

Aerosol–cloud–radiation interactions are widely held to be the largest single source of uncertainty in climate model projections of future radiative forcing due to increasing anthropogenic emissions. The underlying causes of this uncertainty among modeled predictions of climate are the gaps in our fundamental understanding of cloud processes. There has been significant progress with both observations and models in addressing these important questions but quantifying them correctly is nontrivial, thus limiting our ability to represent them in global climate models. The Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE) 2011 was a targeted aircraft campaign with embedded modeling studies, using the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft and the research vessel Point Sur in July and August 2011 off the central coast of California, with a full payload of instruments to measure particle and cloud number, mass, composition, and water uptake distributions. EPEACE used three emitted particle sources to separate particle-induced feedbacks from dynamical variability, namely 1) shipboard smoke-generated particles with 0.05–1-μm diameters (which produced tracks measured by satellite and had drop composition characteristic of organic smoke), 2) combustion particles from container ships with 0.05–0.2-μm diameters (which were measured in a variety of conditions with droplets containing both organic and sulfate components), and 3) aircraft-based milled salt particles with 3–5-μm diameters (which showed enhanced drizzle rates in some clouds). The aircraft observations were consistent with past large-eddy simulations of deeper clouds in ship tracks and aerosol– cloud parcel modeling of cloud drop number and composition, providing quantitative constraints on aerosol effects on warm-cloud microphysics.

scholarly journals Global Potato Yields Increase Under Climate Change With Adaptation and CO2 Fertilisation

2020 ◽  
Vol 4 ◽  
Author(s):  
Stewart A. Jennings ◽  
Ann-Kristin Koehler ◽  
Kathryn J. Nicklin ◽  
Chetan Deva ◽  
Steven M. Sait ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Global Climate ◽  
Climate Change Impacts ◽  
Global Scale ◽  
Global Climate Models ◽  
Adaptation To Climate Change ◽  
National Scale ◽  
Modeling Studies ◽  
Potato Yields

The contribution of potatoes to the global food supply is increasing—consumption more than doubled in developing countries between 1960 and 2005. Understanding climate change impacts on global potato yields is therefore important for future food security. Analyses of climate change impacts on potato compared to other major crops are rare, especially at the global scale. Of two global gridded potato modeling studies published at the time of this analysis, one simulated the impacts of temperature increases on potential potato yields; the other did not simulate the impacts of farmer adaptation to climate change, which may offset negative climate change impacts on yield. These studies may therefore overestimate negative climate change impacts on yields as they do not simultaneously include CO2 fertilisation and adaptation to climate change. Here we simulate the abiotic impacts of climate change on potato to 2050 using the GLAM crop model and the ISI-MIP ensemble of global climate models. Simulations include adaptations to climate change through varying planting windows and varieties and CO2 fertilisation, unlike previous global potato modeling studies. Results show significant skill in reproducing observed national scale yields in Europe. Elsewhere, correlations are generally positive but low, primarily due to poor relationships between national scale observed yields and climate. Future climate simulations including adaptation to climate change through changing planting windows and crop varieties show that yields are expected to increase in most cases as a result of longer growing seasons and CO2 fertilisation. Average global yield increases range from 9 to 20% when including adaptation. The global average yield benefits of adaptation to climate change range from 10 to 17% across climate models. Potato agriculture is associated with lower green house gas emissions relative to other major crops and therefore can be seen as a climate smart option given projected yield increases with adaptation.

scholarly journals An evaluation of the importance of spatial resolution in a global climate and hydrological model based on the Rhine and Mississippi basin

2017 ◽  
Author(s):  
Imme Benedict ◽  
Chiel C. van Heerwaarden ◽  
Albrecht H. Weerts ◽  
Wilco Hazeleger
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Large Scale ◽  
Climate Models ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Scale ◽  
Global Climate Models ◽  
Convective Processes ◽  
Parameter Values

Abstract. The hydrological cycle of river basins can be simulated by combining global climate models (GCMs) and global hydrological models (GHMs). The spatial resolution of these models is restricted by computational resources and therefore limits the processes and level of detail that can be resolved. To further improve simulations of precipitation and river-runoff on a global scale, we assess and compare the benefits of an increased resolution for a GCM and a GHM. We focus on the Rhine and Mississippi basin. Increasing the resolution of a GCM (1.125° to 0.25°) results in more realistic large-scale circulation patterns over the Rhine and an improved precipitation budget. These improvements with increased resolution are not found for the Mississippi basin, most likely because precipitation is strongly dependent on the representation of still unresolved convective processes. Increasing the resolution of vegetation and orography in the high resolution GHM (from 0.5° to 0.05°) shows no significant differences in discharge for both basins, because the hydrological processes depend highly on other parameter values that are not readily available at high resolution. Therefore, increasing the resolution of the GCM provides the most straightforward route to better results. This route works best for basins driven by large-scale precipitation, such as the Rhine basin. For basins driven by convective processes, such as the Mississippi basin, improvements are expected with even higher resolution convection permitting models.

scholarly journals Modeled Arctic sea ice evolution through 2300 in CMIP5 extended RCPs

2014 ◽  
Vol 8 (1) ◽  
pp. 1383-1406 ◽  
Author(s):  
P. J. Hezel ◽  
T. Fichefet ◽  
F. Massonnet
Keyword(s):  
Sea Ice ◽  
Radiative Forcing ◽  
Climate Models ◽  
Global Climate ◽  
Arctic Sea Ice ◽  
Global Climate Models ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Arctic Sea ◽  
Arctic Sea Ice Extent

Abstract. Almost all global climate models and Earth system models that participated in the Coupled Model Intercomparison Project 5 (CMIP5) show strong declines in Arctic sea ice extent and volume under the highest forcing scenario of the Radiative Concentration Pathways (RCPs) through 2100, including a transition from perennial to seasonal ice cover. Extended RCP simulations through 2300 were completed for a~subset of models, and here we examine the time evolution of Arctic sea ice in these simulations. In RCP2.6, the summer Arctic sea ice extent increases compared to its minimum following the peak radiative forcing in 2044 in all 9 models. RCP4.5 demonstrates continued summer Arctic sea ice decline due to continued warming on longer time scales. These two scenarios imply that summer sea ice extent could begin to recover if and when radiative forcing from greenhouse gas concentrations were to decrease. In RCP8.5 the Arctic Ocean reaches annually ice-free conditions in 7 of 9 models. The ensemble of simulations completed under the extended RCPs provide insight into the global temperature increase at which sea ice disappears in the Arctic and reversibility of declines in seasonal sea ice extent.

scholarly journals An Equatorial Ocean Bottleneck in Global Climate Models

2012 ◽  
Vol 25 (1) ◽  
pp. 343-349 ◽  
Author(s):  
Kristopher B. Karnauskas ◽  
Gregory C. Johnson ◽  
Raghu Murtugudde
Keyword(s):  
Ocean Circulation ◽  
Radiative Forcing ◽  
Climate Models ◽  
Global Climate ◽  
Critical Role ◽  
Tropical Pacific ◽  
Global Climate Models ◽  
Momentum Balance ◽  
Equatorial Ocean ◽  
The Tropical Pacific

Abstract The Equatorial Undercurrent (EUC) is a major component of the tropical Pacific Ocean circulation. EUC velocity in most global climate models is sluggish relative to observations. Insufficient ocean resolution slows the EUC in the eastern Pacific where nonlinear terms should dominate the zonal momentum balance. A slow EUC in the east creates a bottleneck for the EUC to the west. However, this bottleneck does not impair other major components of the tropical circulation, including upwelling and poleward transport. In most models, upwelling velocity and poleward transport divergence fall within directly estimated uncertainties. Both of these transports play a critical role in a theory for how the tropical Pacific may change under increased radiative forcing, that is, the ocean dynamical thermostat mechanism. These findings suggest that, in the mean, global climate models may not underrepresent the role of equatorial ocean circulation, nor perhaps bias the balance between competing mechanisms for how the tropical Pacific might change in the future. Implications for model improvement under higher resolution are also discussed.

scholarly journals Exploring aerosol–cloud interaction using VOCALS-REx aircraft measurements

2019 ◽  
Vol 19 (12) ◽  
pp. 7955-7971 ◽  
Author(s):  
Hailing Jia ◽  
Xiaoyan Ma ◽  
Yangang Liu
Keyword(s):  
Climate Models ◽  
Global Climate ◽  
Cloud Droplet ◽  
Global Climate Models ◽  
Relative Dispersion ◽  
Aircraft Measurements ◽  
Aerosol Cloud ◽  
Dispersion Effects ◽  
Entrainment Zone ◽  
Entrainment Mixing

Abstract. In situ aircraft measurements obtained during the VAMOS (Variability of the American Monsoons) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) field campaign are analyzed to study the aerosol–cloud interactions in the stratocumulus clouds over the southeastern Pacific Ocean (SEP), with a focus on three understudied topics (separation of aerosol effects from dynamic effects, dispersion effects, and turbulent entrainment-mixing processes). Our analysis suggests that an increase in aerosol concentration tends to simultaneously increase both cloud droplet number concentration (Nd) and relative dispersion (ε), while an increase in vertical velocity (w) often increases Nd but decreases ε. After constraining the differences of cloud dynamics, the positive correlation between ε and Nd becomes stronger, implying that perturbations of w could weaken the aerosol influence on ε and hence result in an underestimation of dispersion effect. A comparative analysis of the difference of cloud microphysical properties between the entrainment and non-entrainment zones suggests that the entrainment-mixing mechanism is predominantly extremely inhomogeneous in the stratocumulus that capped by a sharp inversion, whereby the variation in liquid water content (25 %) is similar to that of Nd (29 %) and the droplet size remains approximately constant. In entrainment zone, drier air entrained from the top induces fewer cloud droplets with respect to total in-cloud particles (0.56±0.22) than the case in the non-entrainment zone (0.73±0.13) by promoting cloud droplet evaporation. This study is helpful in reducing uncertainties in dispersion effects and entrainment mixing for stratocumulus, and the results of this study may benefit cloud parameterizations in global climate models to more accurately assess aerosol indirect effects.

scholarly journals Evaluating Climate Model Simulations of the Radiative Forcing and Radiative Response at Earth’s Surface

2019 ◽  
Vol 32 (13) ◽  
pp. 4089-4102 ◽  
Author(s):  
Ryan J. Kramer ◽  
Brian J. Soden ◽  
Angeline G. Pendergrass
Keyword(s):  
Radiative Forcing ◽  
Climate Models ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Models ◽  
Lapse Rate ◽  
Radiation Budget ◽  
Model Simulations ◽  
Climate Model Simulations

Abstract We analyze the radiative forcing and radiative response at Earth’s surface, where perturbations in the radiation budget regulate the atmospheric hydrological cycle. By applying a radiative kernel-regression technique to CMIP5 climate model simulations where CO2 is instantaneously quadrupled, we evaluate the intermodel spread in surface instantaneous radiative forcing, radiative adjustments to this forcing, and radiative responses to surface warming. The cloud radiative adjustment to CO2 forcing and the temperature-mediated cloud radiative response exhibit significant intermodel spread. In contrast to its counterpart at the top of the atmosphere, the temperature-mediated cloud radiative response at the surface is found to be positive in some models and negative in others. Also, the compensation between the temperature-mediated lapse rate and water vapor radiative responses found in top-of-atmosphere calculations is not present for surface radiative flux changes. Instantaneous radiative forcing at the surface is rarely reported for model simulations; as a result, intermodel differences have not previously been evaluated in global climate models. We demonstrate that the instantaneous radiative forcing is the largest contributor to intermodel spread in effective radiative forcing at the surface. We also find evidence of differences in radiative parameterizations in current models and argue that this is a significant, but largely overlooked, source of bias in climate change simulations.

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