Can aerosol decrease cloud lifetime?

Griswold, Jennifer D. Small; Chuang, P. Y.; Feingold, Graham; Jiang, Hongli

doi:10.1029/2009gl038888

Cited by 197 publications

(246 citation statements)

References 45 publications

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“…Such an effect would lead to deeper clouds, and more intense precipitation, although Rosenfeld et al (2008) pointed out that effects of aerosols might be not linear on storm invigoration. There is a large variety of processes "buffering" such aerosol effects on clouds (Stevens and Feingold, 2009), such as a larger evaporation rate of smaller droplets (Small et al, 2009), or increased droplet spectrum dispersion (Liu and Daum, 2002). If anthropogenic aerosols are strongly absorbing sunlight, they may alter the thermodynamic structure of the troposphere.…”

Section: Brief Summary Of Direct and Indirect Aerosol Effectsmentioning

confidence: 99%

Assessing large-scale weekly cycles in meteorological variables: a review

Sánchez-Lorenzo¹,

Laux

Franssen³

et al. 2012

Atmos. Chem. Phys.

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Abstract. Several studies have claimed to have found significant weekly cycles of meteorological variables appearing over large domains, which can hardly be related to urban effects exclusively. Nevertheless, there is still an ongoing scientific debate whether these large-scale weekly cycles exist or not, and some other studies fail to reproduce them with statistical significance. In addition to the lack of the positive proof for the existence of these cycles, their possible physical explanations have been controversially discussed during the last years. In this work we review the main results about this topic published during the recent two decades, including a summary of the existence or non-existence of significant weekly weather cycles across different regions of the world, mainly over the US, Europe and Asia. In addition, some shortcomings of common statistical methods for analyzing weekly cycles are listed. Finally, a brief summary of supposed causes of the weekly cycles, focusing on the aerosol-cloud-radiation interactions and their impact on meteorological variables as a result of the weekly cycles of anthropogenic activities, and possible directions for future research, is presented.

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Section: Brief Summary Of Direct and Indirect Aerosol Effectsmentioning

confidence: 99%

Assessing large-scale weekly cycles in meteorological variables: a review

Sánchez-Lorenzo¹,

Laux

Franssen³

et al. 2012

Atmos. Chem. Phys.

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“…More cloud droplets increase the total droplet surface area by which the cloud albedo is enhanced; an effect which was put into the general context of anthropogenic pollution by Twomey (1974). Other AIE-hypotheses include effects on cloud lifetime (Albrecht, 1989;Small et al, 2009) or cloud top height (Koren et al,…”

Section: Introductionmentioning

confidence: 99%

Aerosol indirect effects from shipping emissions: sensitivity studies with the global aerosol-climate model ECHAM-HAM

et al. 2012

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Abstract. In this study, we employ the global aerosol-climate model ECHAM-HAM to globally assess aerosol indirect effects (AIEs) resulting from shipping emissions of aerosols and aerosol precursor gases. We implement shipping emissions of sulphur dioxide (SO 2 ), black carbon (BC) and particulate organic matter (POM) for the year 2000 into the model and quantify the model's sensitivity towards uncertainties associated with the emission parameterisation as well as with the shipping emissions themselves. Sensitivity experiments are designed to investigate (i) the uncertainty in the size distribution of emitted particles, (ii) the uncertainty associated with the total amount of emissions, and (iii) the impact of reducing carbonaceous emissions from ships.We use the results from one sensitivity experiment for a detailed discussion of shipping-induced changes in the global aerosol system as well as the resulting impact on cloud properties. From all sensitivity experiments, we find AIEs from shipping emissions to range from −0.32 ± 0.01 W m −2 to −0.07 ± 0.01 W m −2 (global mean value and inter-annual variability as a standard deviation). The magnitude of the AIEs depends much more on the assumed emission size distribution and subsequent aerosol microphysical interactions than on the magnitude of the emissions themselves. It is important to note that although the strongest estimate of AIEs from shipping emissions in this study is relatively large, still much larger estimates have been reported in the literature before on the basis of modelling studies. We find that omitting just carbonaceous particle emissions from ships favours new particle formation in the boundary layer. These newly formed particles contribute just about as much to the CCN budget as the carbonaceous particles would, leaving the globally averaged AIEs nearly unaltered compared to a simulation including carbonaceous particle emissions from ships.

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“…Aerosol-radiation interactions may lead to cloud changes, especially via local heating due to absorption of sunlight [Ackerman et al, 2000]. Aerosol-cloud interactions imply changes in microphysical [Albrecht, 1989;Pincus and Baker, 1994;Lohmann, 2002;Fan et al, 2013] and dynamical [Ackerman et al, 2004;Small et al, 2009] cloud processes. The hypothesis that with suppression of rain formation in the liquid phase in convective clouds, lifting of additional water to the freezing level that might lead to enhanced buoyancy has been called "thermodynamic effect" [Denman et al, 2007] or also "convective invigoration" [Koren et al, 2005] and is considered in our nomenclature part of the cloud microphysical adjustments.…”

Section: Introductionmentioning

confidence: 99%

Assessment of simulated aerosol effective radiative forcings in the terrestrial spectrum

Heyn

Block

Mülmenstädt

et al. 2017

Geophysical Research Letters

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In its fifth assessment report (AR5), the Intergovernmental Panel on Climate Change provides a best estimate of the effective radiative forcing (ERF) due to anthropogenic aerosol at −0.9 W m−2. This value is considerably weaker than the estimate of −1.2 W m−2 in AR4. A part of the difference can be explained by an offset of +0.2 W m−2 which AR5 added to all published estimates that only considered the solar spectrum, in order to account for adjustments in the terrestrial spectrum. We find that, in the CMIP5 multimodel median, the ERF in the terrestrial spectrum is small, unless microphysical effects on ice‐ and mixed‐phase clouds are parameterized. In the latter case it is large but accompanied by a very strong ERF in the solar spectrum. The total adjustments can be separated into microphysical adjustments (aerosol “effects”) and thermodynamic adjustments. Using a kernel technique, we quantify the latter and find that the rapid thermodynamic adjustments of water vapor and temperature profiles are small. Observation‐based constraints on these model results are urgently needed.

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Can aerosol decrease cloud lifetime?

Cited by 197 publications

References 45 publications

Assessing large-scale weekly cycles in meteorological variables: a review

Assessing large-scale weekly cycles in meteorological variables: a review

Aerosol indirect effects from shipping emissions: sensitivity studies with the global aerosol-climate model ECHAM-HAM

Assessment of simulated aerosol effective radiative forcings in the terrestrial spectrum

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