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  • 1
    Online Resource
    Online Resource
    A production-tagged aerosol module for Earth system models, OsloAero5.3 – extensions and updates for CAM5.3-Oslo
    Copernicus GmbH ; 2018
    In:  Geoscientific Model Development Vol. 11, No. 10 ( 2018-10-01), p. 3945-3982
    Details
    In: Geoscientific Model Development, Copernicus GmbH, Vol. 11, No. 10 ( 2018-10-01), p. 3945-3982
    Abstract: Abstract. We document model updates and present and discuss modeling and validation results from a further developed production-tagged aerosol module, OsloAero5.3, for use in Earth system models. The aerosol module has in this study been implemented and applied in CAM5.3-Oslo. This model is based on CAM5.3–CESM1.2 and its own predecessor model version CAM4-Oslo. OsloAero5.3 has improved treatment of emissions, aerosol chemistry, particle life cycle, and aerosol–cloud interactions compared to its predecessor OsloAero4.0 in CAM4-Oslo. The main new features consist of improved aerosol sources; the module now explicitly accounts for aerosol particle nucleation and secondary organic aerosol production, with new emissions schemes also for sea salt, dimethyl sulfide (DMS), and marine primary organics. Mineral dust emissions are updated as well, adopting the formulation of CESM1.2. The improved model representation of aerosol–cloud interactions now resolves heterogeneous ice nucleation based on black carbon (BC) and mineral dust calculated by the model and treats the activation of cloud condensation nuclei (CCN) as in CAM5.3. Compared to OsloAero4.0 in CAM4-Oslo, the black carbon (BC) mass concentrations are less excessive aloft, with a better fit to observations. Near-surface mass concentrations of BC and sea salt aerosols are also less biased, while sulfate and mineral dust are slightly more biased. Although appearing quite similar for CAM5.3-Oslo and CAM4-Oslo, the validation results for organic matter (OM) are inconclusive, since both of the respective versions of OsloAero are equipped with a limited number of OM tracers for the sake of computational efficiency. Any information about the assumed mass ratios of OM to organic carbon (OC) for different types of OM sources is lost in the transport module. Assuming that observed OC concentrations scaled by 1.4 are representative for the modeled OM concentrations, CAM5.3-Oslo with OsloAero5.3 is slightly inferior for the very sparsely available observation data. Comparing clear-sky column-integrated optical properties with data from ground-based remote sensing, we find a negative bias in optical depth globally; however, it is not as strong as in CAM4-Oslo, but has positive biases in some areas typically dominated by mineral dust emissions. Aerosol absorption has a larger negative bias than the optical depth globally. This is reflected in a lower positive bias in areas where mineral dust is the main contributor to absorption. Globally, the low bias in absorption is smaller than in CAM4-Oslo. The Ångström parameter exhibits small biases both globally and regionally, suggesting that the aerosol particle sizes are reasonably well represented. Cloud-top droplet number concentrations over oceans are generally underestimated compared to satellite retrievals, but seem to be overestimated downwind of major emissions of dust and biomass burning sources. Finally, we find small changes in direct radiative forcing at the top of the atmosphere, while the cloud radiative forcing due to anthropogenic aerosols is now more negative than in CAM4-Oslo, being on the strong side compared to the multi-model estimate in IPCC AR5. Although not all validation results in this study show improvement for the present CAM5.3-Oslo version, the extended and updated aerosol module OsloAero5.3 is more advanced and applicable than its predecessor OsloAero4.0, as it includes new parameterizations that more readily facilitate sensitivity and process studies and use in climate and Earth system model studies in general.
    Type of Medium: Online Resource
    ISSN: 1991-9603
    URL: Article
    URL: Article
    DOI: 10.5194/gmd-11-3945-2018
    DOI: 10.5194/gmd-11-3945-2018-corrigendum
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2018
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  • 2
    Online Resource
    Online Resource
    Overview of the Norwegian Earth System Model (NorESM2) and key climate response of CMIP6 DECK, historical, and scenario simulations
    Copernicus GmbH ; 2020
    In:  Geoscientific Model Development Vol. 13, No. 12 ( 2020-12-04), p. 6165-6200
    Details
    In: Geoscientific Model Development, Copernicus GmbH, Vol. 13, No. 12 ( 2020-12-04), p. 6165-6200
    Abstract: Abstract. The second version of the coupled Norwegian Earth System Model (NorESM2) is presented and evaluated. NorESM2 is based on the second version of the Community Earth System Model (CESM2) and shares with CESM2 the computer code infrastructure and many Earth system model components. However, NorESM2 employs entirely different ocean and ocean biogeochemistry models. The atmosphere component of NorESM2 (CAM-Nor) includes a different module for aerosol physics and chemistry, including interactions with cloud and radiation; additionally, CAM-Nor includes improvements in the formulation of local dry and moist energy conservation, in local and global angular momentum conservation, and in the computations for deep convection and air–sea fluxes. The surface components of NorESM2 have minor changes in the albedo calculations and to land and sea-ice models. We present results from simulations with NorESM2 that were carried out for the sixth phase of the Coupled Model Intercomparison Project (CMIP6). Two versions of the model are used: one with lower (∼ 2∘) atmosphere–land resolution and one with medium (∼ 1∘) atmosphere–land resolution. The stability of the pre-industrial climate and the sensitivity of the model to abrupt and gradual quadrupling of CO2 are assessed, along with the ability of the model to simulate the historical climate under the CMIP6 forcings. Compared to observations and reanalyses, NorESM2 represents an improvement over previous versions of NorESM in most aspects. NorESM2 appears less sensitive to greenhouse gas forcing than its predecessors, with an estimated equilibrium climate sensitivity of 2.5 K in both resolutions on a 150-year time frame; however, this estimate increases with the time window and the climate sensitivity at equilibration is much higher. We also consider the model response to future scenarios as defined by selected Shared Socioeconomic Pathways (SSPs) from the Scenario Model Intercomparison Project defined under CMIP6. Under the four scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5), the warming in the period 2090–2099 compared to 1850–1879 reaches 1.3, 2.2, 3.0, and 3.9 K in NorESM2-LM, and 1.3, 2.1, 3.1, and 3.9 K in NorESM-MM, robustly similar in both resolutions. NorESM2-LM shows a rather satisfactory evolution of recent sea-ice area. In NorESM2-LM, an ice-free Arctic Ocean is only avoided in the SSP1-2.6 scenario.
    Type of Medium: Online Resource
    ISSN: 1991-9603
    URL: Article
    URL: Article
    DOI: 10.5194/gmd-13-6165-2020
    DOI: 10.5194/gmd-13-6165-2020-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2020
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  • 3
    Online Resource
    Online Resource
    Evaluation of global simulations of aerosol particle and cloud condensation nuclei number, with implications for cloud droplet formation
    Copernicus GmbH ; 2019
    In:  Atmospheric Chemistry and Physics Vol. 19, No. 13 ( 2019-07-08), p. 8591-8617
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 19, No. 13 ( 2019-07-08), p. 8591-8617
    Abstract: Abstract. A total of 16 global chemistry transport models and general circulation models have participated in this study; 14 models have been evaluated with regard to their ability to reproduce the near-surface observed number concentration of aerosol particles and cloud condensation nuclei (CCN), as well as derived cloud droplet number concentration (CDNC). Model results for the period 2011–2015 are compared with aerosol measurements (aerosol particle number, CCN and aerosol particle composition in the submicron fraction) from nine surface stations located in Europe and Japan. The evaluation focuses on the ability of models to simulate the average across time state in diverse environments and on the seasonal and short-term variability in the aerosol properties. There is no single model that systematically performs best across all environments represented by the observations. Models tend to underestimate the observed aerosol particle and CCN number concentrations, with average normalized mean bias (NMB) of all models and for all stations, where data are available, of −24 % and −35 % for particles with dry diameters 〉50 and 〉120 nm, as well as −36 % and −34 % for CCN at supersaturations of 0.2 % and 1.0 %, respectively. However, they seem to behave differently for particles activating at very low supersaturations (〈0.1 %) than at higher ones. A total of 15 models have been used to produce ensemble annual median distributions of relevant parameters. The model diversity (defined as the ratio of standard deviation to mean) is up to about 3 for simulated N3 (number concentration of particles with dry diameters larger than 3 nm) and up to about 1 for simulated CCN in the extra-polar regions. A global mean reduction of a factor of about 2 is found in the model diversity for CCN at a supersaturation of 0.2 % (CCN0.2) compared to that for N3, maximizing over regions where new particle formation is important. An additional model has been used to investigate potential causes of model diversity in CCN and bias compared to the observations by performing a perturbed parameter ensemble (PPE) accounting for uncertainties in 26 aerosol-related model input parameters. This PPE suggests that biogenic secondary organic aerosol formation and the hygroscopic properties of the organic material are likely to be the major sources of CCN uncertainty in summer, with dry deposition and cloud processing being dominant in winter. Models capture the relative amplitude of the seasonal variability of the aerosol particle number concentration for all studied particle sizes with available observations (dry diameters larger than 50, 80 and 120 nm). The short-term persistence time (on the order of a few days) of CCN concentrations, which is a measure of aerosol dynamic behavior in the models, is underestimated on average by the models by 40 % during winter and 20 % in summer. In contrast to the large spread in simulated aerosol particle and CCN number concentrations, the CDNC derived from simulated CCN spectra is less diverse and in better agreement with CDNC estimates consistently derived from the observations (average NMB −13 % and −22 % for updraft velocities 0.3 and 0.6 m s−1, respectively). In addition, simulated CDNC is in slightly better agreement with observationally derived values at lower than at higher updraft velocities (index of agreement 0.64 vs. 0.65). The reduced spread of CDNC compared to that of CCN is attributed to the sublinear response of CDNC to aerosol particle number variations and the negative correlation between the sensitivities of CDNC to aerosol particle number concentration (∂Nd/∂Na) and to updraft velocity (∂Nd/∂w). Overall, we find that while CCN is controlled by both aerosol particle number and composition, CDNC is sensitive to CCN at low and moderate CCN concentrations and to the updraft velocity when CCN levels are high. Discrepancies are found in sensitivities ∂Nd/∂Na and ∂Nd/∂w; models may be predisposed to be too “aerosol sensitive” or “aerosol insensitive” in aerosol–cloud–climate interaction studies, even if they may capture average droplet numbers well. This is a subtle but profound finding that only the sensitivities can clearly reveal and may explain inter-model biases on the aerosol indirect effect.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    URL: Article
    DOI: 10.5194/acp-19-8591-2019
    DOI: 10.5194/acp-19-8591-2019-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2019
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  • 4
    Online Resource
    Online Resource
    Strong impacts on aerosol indirect effects from historical oxidant changes
    Copernicus GmbH ; 2018
    In:  Atmospheric Chemistry and Physics Vol. 18, No. 10 ( 2018-06-01), p. 7669-7690
    Details
    In: Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 18, No. 10 ( 2018-06-01), p. 7669-7690
    Abstract: Abstract. Uncertainties in effective radiative forcings through aerosol–cloud interactions (ERFaci, also called aerosol indirect effects) contribute strongly to the uncertainty in the total preindustrial-to-present-day anthropogenic forcing. Some forcing estimates of the total aerosol indirect effect are so negative that they even offset the greenhouse gas forcing. This study highlights the role of oxidants in modeling of preindustrial-to-present-day aerosol indirect effects. We argue that the aerosol precursor gases should be exposed to oxidants of its era to get a more correct representation of secondary aerosol formation. Our model simulations show that the total aerosol indirect effect changes from −1.32 to −1.07 W m−2 when the precursor gases in the preindustrial simulation are exposed to preindustrial instead of present-day oxidants. This happens because of a brightening of the clouds in the preindustrial simulation, mainly due to large changes in the nitrate radical (NO3). The weaker oxidative power of the preindustrial atmosphere extends the lifetime of the precursor gases, enabling them to be transported higher up in the atmosphere and towards more remote areas where the susceptibility of the cloud albedo to aerosol changes is high. The oxidation changes also shift the importance of different chemical reactions and produce more condensate, thus increasing the size of the aerosols and making it easier for them to activate as cloud condensation nuclei.
    Type of Medium: Online Resource
    ISSN: 1680-7324
    URL: Article
    DOI: 10.5194/acp-18-7669-2018
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2018
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  • 5
    Online Resource
    Online Resource
    Evaluation of the aerosol vertical distribution in global aerosol models through comparison against CALIOP measurements: AeroCom phase II results
    American Geophysical Union (AGU) ; 2016
    In:  Journal of Geophysical Research: Atmospheres Vol. 121, No. 12 ( 2016-06-27), p. 7254-7283
    Details
    In: Journal of Geophysical Research: Atmospheres, American Geophysical Union (AGU), Vol. 121, No. 12 ( 2016-06-27), p. 7254-7283
    Abstract: The ability of 11 global models in simulating the aerosol vertical distribution is assessed Hypotheses for the models performance and evolution and for the inter‐model diversity are discussed An analysis of CALIOP limitations and uncertainties contributing to the discrepancies is provided
    Type of Medium: Online Resource
    ISSN: 2169-897X , 2169-8996
    URL: Issue
    URL: Article
    DOI: 10.1002/jgrd.v121.12
    DOI: 10.1002/2015JD024639
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2016
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    SSG: 16,13
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  • 6
    Online Resource
    Online Resource
    Remote sensing of aerosols in the Arctic for an evaluation of global climate model simulations
    American Geophysical Union (AGU) ; 2014
    In:  Journal of Geophysical Research: Atmospheres Vol. 119, No. 13 ( 2014-07-16), p. 8169-8188
    Details
    In: Journal of Geophysical Research: Atmospheres, American Geophysical Union (AGU), Vol. 119, No. 13 ( 2014-07-16), p. 8169-8188
    Type of Medium: Online Resource
    ISSN: 2169-897X , 2169-8996
    URL: Issue
    URL: Article
    DOI: 10.1002/jgrd.v119.13
    DOI: 10.1002/2013JD021279
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2014
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    SSG: 16,13
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  • 7
    Online Resource
    Online Resource
    On the additivity of climate response to anthropogenic aerosols and CO〈sub〉2〈/sub〉, and the enhancement of future global warming by carbonaceous aerosols
    Stockholm University Press ; 2008
    In:  Tellus A: Dynamic Meteorology and Oceanography Vol. 60, No. 3 ( 2008-01-01), p. 513-
    Details
    In: Tellus A: Dynamic Meteorology and Oceanography, Stockholm University Press, Vol. 60, No. 3 ( 2008-01-01), p. 513-
    Type of Medium: Online Resource
    ISSN: 1600-0870
    URL: Article
    DOI: 10.1111/j.1600-0870.2007.00308.x
    Language: Unknown
    Publisher: Stockholm University Press
    Publication Date: 2008
    detail.hit.zdb_id: 2026987-0
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  • 8
    Online Resource
    Online Resource
    Aerosol-climate interactions in the CAM-Oslo atmospheric GCM and investigation of associated basic shortcomings
    Stockholm University Press ; 2008
    In:  Tellus A: Dynamic Meteorology and Oceanography Vol. 60, No. 3 ( 2008-01-01), p. 459-
    Details
    In: Tellus A: Dynamic Meteorology and Oceanography, Stockholm University Press, Vol. 60, No. 3 ( 2008-01-01), p. 459-
    Type of Medium: Online Resource
    ISSN: 1600-0870
    URL: Article
    DOI: 10.1111/j.1600-0870.2007.00318.x
    Language: Unknown
    Publisher: Stockholm University Press
    Publication Date: 2008
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  • 9
    Online Resource
    Online Resource
    Absorbing aerosols over Asia – an inter-model and model-observation comparison study using CAM5.3-Oslo
    Stockholm University Press ; 2021
    In:  Tellus B: Chemical and Physical Meteorology Vol. 73, No. 1 ( 2021-01-01), p. 1909815-
    Details
    In: Tellus B: Chemical and Physical Meteorology, Stockholm University Press, Vol. 73, No. 1 ( 2021-01-01), p. 1909815-
    Type of Medium: Online Resource
    ISSN: 1600-0889 , 0280-6509
    URL: Article
    DOI: 10.1080/16000889.2021.1909815
    RVK:
    RA 1000
    RVK:
    UA 8382.2
    Language: Unknown
    Publisher: Stockholm University Press
    Publication Date: 2021
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    SSG: 16,13
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  • 10
    Online Resource
    Online Resource
    Global direct radiative forcing by process-parameterized aerosol optical properties
    American Geophysical Union (AGU) ; 2002
    In:  Journal of Geophysical Research Vol. 107, No. D20 ( 2002)
    Details
    In: Journal of Geophysical Research, American Geophysical Union (AGU), Vol. 107, No. D20 ( 2002)
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/2001JD000886
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2002
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