Aerosol nucleation over oceans and the role of galactic cosmic rays

Kazil, J.; Lovejoy, Edward R.; Barth, M. C.; O’Brien, K.

doi:10.5194/acp-6-4905-2006

Cited by 89 publications

(68 citation statements)

References 78 publications

(100 reference statements)

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“…Other nucleation mechanisms may also contribute to boundary layer nucleation: for example iodinedriven nucleation can be a significant source of new particles in coastal areas (O'Dowd and de Leeuw, 2007). We have represented nucleation in the upper troposphere with neutral binary homogeneous nucleation of sulfuric acid and water, but it is possible that ion-induced nucleation can be the dominant source in UT and possibly significantly contributes to boundary layer nucleation as well (Lovejoy et al, 2004;Kazil et al, 2006;Yu et al, 2008). Uncertainties are also related to the yield of condensing secondary organic vapor, which can modify the obtained aerosol size distributions considerably and enhance the particle growth rates to CCN sizes.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…While work is in progress to better quantify different aerosol processes, global models including detailed microphysics have contributed greatly to the knowledge of mechanisms controlling particle concentrations in different regions. Pierce and Adams (2006), Kazil et al (2006) and Spracklen et al (2007) showed that remote marine boundary layer CCN concentrations can be largely explained by the primary sea salt flux and entrainment of free tropospheric particles, as originally proposed by Raes (1995). In a subsequent study Korhonen et al (2008) used a global aerosol model to explain the seasonal cycle of CCN at Cape Grim based on emissions of sea spray and nucleation of sulfuric acid aerosol in the free troposphere, and estimated that over 90% of the non-sea spray CCN were generated above the boundary layer by nucleation.…”

Section: Introductionmentioning

confidence: 99%

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Impact of nucleation on global CCN

et al. 2009

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Abstract. Cloud condensation nuclei (CCN) are derived from particles emitted directly into the atmosphere (primary emissions) or from the growth of nanometer-sized particles nucleated in the atmosphere. It is important to separate these two sources because they respond in different ways to gas and particle emission control strategies and environmental changes. Here, we use a global aerosol microphysics model to quantify the contribution of primary and nucleated particles to global CCN. The model considers primary emissions of sea spray, sulfate and carbonaceous particles, and nucleation processes appropriate for the free troposphere and boundary layer. We estimate that 45% of global low-level cloud CCN at 0.2% supersaturation are secondary aerosol derived from nucleation (ranging between 31-49% taking into account uncertainties in primary emissions and nucleation rates), with the remainder from primary emissions. The model suggests that 35% of CCN (0.2%) in global low-level clouds were created in the free and upper troposphere. In the marine boundary layer 55% of CCN (0.2%) are from nucleation, with 45% entrained from the free troposphere and 10% nucleated directly in the boundary layer. Combinations of model runs show that primary and nucleated CCN are non-linearly coupled. In particular, boundary layer nucleated CCN are strongly suppressed by both primary emissions and entrainment of particles nucleated in the free troposphere. Elimination of all primary emissions reduces global CCN (0.2%) by only 20% and elimination of upper tropospheric nucleation reduces CCN (0.2%) by only 12% because of the increased contribution from boundary layer nucleation.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of nucleation on global CCN

et al. 2009

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“…Hence, this supports a direct effect of GCRs rather than irradiance changes. It is expected that any effect would be more significant in clean maritime air where there is a shortage of CCNs for water vapour to condense on, and air ions generated by GCRs may be more significant factor (Kazil et al 2006;Laken et al 2009). …”

Section: Cosmic Ray Modulation Of Cloudsmentioning

confidence: 99%

Solar Influence on Global and Regional Climates

Lockwood

2012

Surv Geophys

152

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The literature relevant to how solar variability influences climate is vast-but much has been based on inadequate statistics and non-robust procedures. The common pitfalls are outlined in this review. The best estimates of the solar influence on the global mean air surface temperature show relatively small effects, compared with the response to anthropogenic changes (and broadly in line with their respective radiative forcings). However, the situation is more interesting when one looks at regional and season variations around the global means. In particular, recent research indicates that winters in Eurasia may have some dependence on the Sun, with more cold winters occurring when the solar activity is low. Advances in modelling ''top-down'' mechanisms, whereby stratospheric changes influence the underlying troposphere, offer promising explanations of the observed phenomena. In contrast, the suggested modulation of low-altitude clouds by galactic cosmic rays provides an increasingly inadequate explanation of observations.

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“…These mechanisms include: binary nucleation in which sulfuric acid vapor and water vapor condense to form the new particles (Jacker-Voirol and Mirabel, 1989;Kulmala et al, 1998;Vehkamäki et al, 2002), ternary nucleation in which sulfuric acid vapor, ammonia and water vapor condense to form the new particles Anttila et al, 2005;Yu, 2006b) and ion-induced nucleation in which gas-phase ions aid in either binary or ternary nucleation (Yu and Turco, 2001;Laakso et al, 2002;Kazil and Lovejoy, 2004;Lovejoy et al, 2004;Kazil et al, 2006;Yu, 2006a). Additionally, cluster activation theory has been proposed to explain the dependence of nucleation rate on sulfuric acid concentrations in the boundary layer Sihto et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Uncertainty in global CCN concentrations from uncertain aerosol nucleation and primary emission rates

2009

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Abstract. The indirect effect of aerosols on climate is highly uncertain and limits our ability to assess anthropogenic climate change. The foundation of this uncertainty is uncertainty in the number of cloud condensation nuclei (CCN), which itself stems from uncertainty in aerosol nucleation, primary emission and growth rates. In this paper, we use a global general circulation model with aerosol microphysics to assess how the uncertainties in aerosol nucleation, emission and growth rates affect our prediction of CCN(0.2%) concentrations. Using several nucleation rate parameterizations that span six orders of magnitude of globally averaged nucleation rates, the tropospheric average CCN(0.2%) concentrations vary by 17% and the boundary layer average vary by 12%. This sensitivity of tropospheric average CCN(0.2%) to the nucleation parameterizations increases to 33% and 20% when the total primary emissions are reduced by a factor of 3 and the SOA condensation rates are increased by a factor of 3.5, respectively. These results show that it is necessary to better understand global nucleation rates when determining CCN concentrations. When primary emissions rates are varied by a factor of 3 while using a binary nucleation parameterization, tropospheric average CCN(0.2%) concentrations also vary by 17%, but boundary layer average vary by 40%. Using the fastest nucleation rate parameterization, these changes drop to 3% and 22%, respectively. These results show the importance of reducing uncertainties in primary emissions, which appear from these results to be somewhat more important for CCN than the much larger uncertainties in nucleation. These results also show that uncertainties in nucleation and primary emissions are more important when sufficient condensable material is available to Correspondence to: J. R. Pierce (jeffrey.robert.pierce@gmail.com) grow them to CCN sizes. The percent change in CCN(0.2%) concentration between pre-industrial times and present day does not depend greatly on the nucleation rate parameterization used for our base case scenarios; however, because other factors, such as primary emissions and SOA, are uncertain in both time periods, this may be a coincidence.

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Aerosol nucleation over oceans and the role of galactic cosmic rays

Cited by 89 publications

References 78 publications

Impact of nucleation on global CCN

Impact of nucleation on global CCN

Solar Influence on Global and Regional Climates

Uncertainty in global CCN concentrations from uncertain aerosol nucleation and primary emission rates

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