Direct shortwave forcing of climate by the anthropogenic sulfate aerosol: Sensitivity to particle size, composition, and relative humidity

Nemesure, S.; Wagener, R.; Schwartz, Stephen E.

doi:10.1029/95jd02897

Cited by 159 publications

(108 citation statements)

References 24 publications

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“…Figure 5 shows an example of this feature. Hygroscopic growth of aerosols and the consequent effects on aerosol light scattering can be assumed to be essentially negligible under such dry conditions (Nemesure et al, 1995;Baumgardner and Clarke, 1998;Im et al, 2001;Redemann et al, 2001;Carrico et al, 2003;Markowicz et al, 2003). Thus, the optical properties of aerosols measured near the surface are likely to be similar to those aloft in a well-mixed boundary layer, which is advantageous for some radiative closure analyses.…”

Section: Instrumentsmentioning

confidence: 99%

The T1-T2 study: evolution of aerosol properties downwind of Mexico City

et al. 2007

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Abstract. As part of a major atmospheric chemistry and aerosol field program carried out in March 2006, a study was conducted in the area to the north and northeast of Mexico City to investigate the evolution of aerosols and their associated optical properties in the first few hours after their emission. The focus of the T1-T2 aerosol study was to investigate changes in the specific absorption α ABS (absorption per unit mass, with unit of m 2 g −1 ) of black carbon as it aged and became coated with compounds such as sulfate and organic carbon, evolving from an external to an internal mixture. Such evolution has been reported in previous studies. The T1 site was located just to the north of the Mexico City metropolitan area; the T2 site was situated approximately 35 km farther to the northeast. Nephelometers, particle soot absorption photometers, photoacoustic absorption spectrometers, and organic and elemental carbon analyzers were used to measure the optical properties of the aerosols and the carbon concentrations at each of the sites. Radar wind profilers and radiosonde systems helped to characterize the meteorology and to identify periods when transport from Mexico City over T1 and T2 occurred. Organic and elemental carbon concentrations at T1 showed diurnal cycles reflecting the nocturnal and early morning buildup from nearby sources, while concentrations at T2 appeared to be more affected by transport from Mexico City. Specific absorption during transport periods was lower than during other times, consistent with the likelihood of fresher emissions being found when the winds blew from Mexico City over T1 and T2. The speCorrespondence to: J. C. Doran (christopher.doran@pnl.gov) cific absorption at T2 was larger than at T1, which is also consistent with the expectation of more aged particles with encapsulated black carbon being found at the more distant location. In situ measurements of single scattering albedo with an aircraft and a ground station showed general agreement with column-averaged values derived from rotating shadowband radiometer data, although some differences were found that may be related to boundary-layer evolution.

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Section: Instrumentsmentioning

confidence: 99%

The T1-T2 study: evolution of aerosol properties downwind of Mexico City

et al. 2007

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“…The forcing mechanisms always depend on the physical properties of the particles, such as their hygroscopic properties and phase states. As humidity cycles, hygroscopic particles can interact with water vapor and change in size, concentration and even chemical composition, all of which can influence light absorption and scattering (Horvath 1993;Nemesure et al 1995;Pilinis et al 1995), cloud condensation nuclei (CCN) activity (Svenningsson et al 1997;Kreidenweis et al 2005) as well as chemical reactivity (Herrmann 2003;Seinfeld and Pandis 2006). The transitions between the solid and aqueous phases at certain points (or in certain ranges) of relative humidity (RH) are described by the deliquescence relative humidity (DRH) where dry particles absorb water and dissolve and the crystallization relative humidity (CRH) at which solution droplets crystallize.…”

Section: Introductionmentioning

confidence: 99%

Water Content and Phase Transitions in Particles of Inorganic and Organic Species and their Mixtures Using Micro-Raman Spectroscopy

Yeung

Chan

2010

Aerosol Science and Technology

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Hygroscopicity and phase transitions were measured with deposited particles of ammonium sulfate (AS), ammonium nitrate (AN), malonic acid (MA), glutaric acid (GA), glyoxylic acid (GlyA), as well as two mixed particle systems AS-MA and AS-GA using micro-Raman spectroscopy. Hygroscopicity was presented in terms of water-to-solute mass ratios, which were obtained from the integrated area ratios of the Raman water band to a distinct solute peak. Deliquescence and crystallization were confirmed by abrupt changes in the Raman peak positions and the full-widthhalf-heights of distinct solute peaks. The results for AS, AN, MA, and GA agreed well with literature reports and model predictions. For GlyA, we detected the Raman water band at near 0% RH, indicating that the spectral technique is sensitive for hygroscopic measurements at very low RH. Additional spectral feature at ∼0% RH was also observed. In the case of more complicated ASdicarboxylic acid mixed systems, the partial phase transitions of the organic components were identified using the intensity ratios of aqueous to solid C=O peaks. AS-MA particles did not completely crystallize and gradual water uptake with increasing RH from 3% was observed. Moreover, it was found that AS-GA particles showed step-wise crystallization in which the AS fraction crystallized prior to the GA fraction. The measured water content and complete DRH of both mixed systems were consistent with the published values. The results show the utility of micro-Raman spectroscopic analysis in studying hygroscopicity and phase characterizations of the chemical species in mixed particles.

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“…Therefore a change of a few watts per square meter in the radiative forcing may produce significant temperature changes in the climate system. Nemesure et al [1995].…”

Section: Introductionmentioning

confidence: 99%

Uncertainty analysis of direct radiative forcing by anthropogenic sulfate aerosols

Pan¹,

Tatang²,

McRae³

et al. 1997

J. Geophys. Res.

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Abstract. Uncertainty in the direct radiative forcing by anthropogenic sulfate aerosols is analyzed for four different aerosol model structures with 13 uncertain parameters using a second-order probabilistic collocation method. The resulting probability density functions agree well with those determined here by a computationally much more expensive 10,000-point Monte Carlo method. The structural difference, measured by the range of the mean responses in models with different approximations, is-0.28 to-1.3 W m -•, and the parametric uncertainty, induced by the uncertainties in the model parameters, is-0.1 to-4.2 W m -•, both with 95% confidence. Th•s implies that refining uncertain input parameters may be more important than improving models in order to minimize the overall uncertainty in the direct radiative forcing by anthropogenic sulfate aerosols in these four models. The variance analysis indicates that the parametric uncertainty comes mainly from sulfate yield, sulfate lifetime, and ambient relative humidity. Variance contributions from aerosol size parameters are much smaller, and this finding agrees with the sensitivity analysis by Boucher and Anderson [1995]. Note that the conclusions reached here are dependent on the chosen model structures and parameter distributions. This study presents a computationally efficient framework for assessing uncertainty in aerosol radiative forcing which could be used to address an even wider range of structures and parameters in the future.

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Direct shortwave forcing of climate by the anthropogenic sulfate aerosol: Sensitivity to particle size, composition, and relative humidity

Cited by 159 publications

References 24 publications

The T1-T2 study: evolution of aerosol properties downwind of Mexico City

The T1-T2 study: evolution of aerosol properties downwind of Mexico City

Water Content and Phase Transitions in Particles of Inorganic and Organic Species and their Mixtures Using Micro-Raman Spectroscopy

Uncertainty analysis of direct radiative forcing by anthropogenic sulfate aerosols

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