Nucleation in the equatorial free troposphere: Favorable environments during PEM‐Tropics

Clarke, A. D.; Eisele, F. L.; Kapustin, V. N.; Moore, K.; Tanner, David J.; Mauldin, L.; Litchy, M.; Lienert, Barry R.; Carroll, Mary Anne; Albercook, George M.

doi:10.1029/98jd02303

Cited by 124 publications

(133 citation statements)

References 34 publications

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“…11), with maximum concentrations simulated in the upper troposphere (UT), as has been observed in recent field campaigns (e.g., Clarke et al, 1999) and simulated in models (Adams and Seinfeld, 2002). Simulated UT concentrations in the tropics peak at higher concentrations and at higher altitudes than at mid latitudes.…”

Section: Global Cn and Ccn Distributionsmentioning

confidence: 68%

A global off-line model of size-resolved aerosol microphysics: I. Model development and prediction of aerosol properties

et al. 2005

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Abstract.A GLObal Model of Aerosol Processes (GLOMAP) has been developed as an extension to the TOMCAT 3-D Eulerian off-line chemical transport model. GLOMAP simulates the evolution of the global aerosol size distribution using a sectional two-moment scheme and includes the processes of aerosol nucleation, condensation, growth, coagulation, wet and dry deposition and cloud processing. We describe the results of a global simulation of sulfuric acid and sea spray aerosol. The model captures features of the aerosol size distribution that are well established from observations in the marine boundary layer and free troposphere. Modelled condensation nuclei (CN >3 nm) vary between about 250-500 cm −3 in remote marine boundary layer regions and are generally in good agreement with observations. Modelled continental CN concentrations are lower than observed, which may be due to lack of some primary aerosol sources or the neglect of nucleation mechanisms other than binary homogeneous nucleation of sulfuric acidwater particles. Remote marine CN concentrations increase to around 2000-10 000 cm −3 (at standard temperature and pressure) in the upper troposphere, which agrees with typical observed vertical profiles. Cloud condensation nuclei (CCN) at 0.2% supersaturation vary between about 1000 cm −3 in polluted regions and between 10 and 500 cm −3 in the remote marine boundary layer. New particle formation through sulfuric acid-water binary nucleation occurs predominantly in the upper troposphere, but the model results show that these particles contribute greatly to aerosol concentrations in the marine boundary layer. For this sulfur-sea salt system it is estimated that sea spray emissions account for only ∼10% of CCN in the tropical marine boundary layer, but between 20 and 75% in the mid-latitude Southern Ocean. In a run with only natural sulfate and sea salt emissions the global mean surface CN concentration is more than 60% of that from a run Correspondence to: D. V. Spracklen (dominick@env.leeds.ac.uk) with 1985 anthropogenic sulfur emissions, although the natural emissions comprise only 27% of total sulfur emissions. Southern hemisphere marine boundary layer CN are more than 90% natural in origin, while polluted continental CN are more than 90% anthropogenic in origin, although these numbers will change when other anthropogenic CN sources are included in the model.

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Section: Global Cn and Ccn Distributionsmentioning

confidence: 68%

A global off-line model of size-resolved aerosol microphysics: I. Model development and prediction of aerosol properties

et al. 2005

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“…The entrainment of aerosols from the FT into the MBL may provide a source of aerosols in the MBL (Raes, 1995;Clarke et al, 1998b;Raes et al, 2000). Clarke (1992) and Clarke et al (1998bClarke et al ( , 1999 reported, based on the experiments on the upper-tropospheric aerosol, new particles and sulfuric acid concentrations in the FT. Weber and McMurry (1996) also reported aerosol size distribution in the FT based on the observations at Mauna Loa Observatory. Their results suggest that the aerosol concentration in the FT shows a consistent shape.…”

Section: Mbl-ft Exchangementioning

confidence: 99%

Modelling the contribution of sea salt and dimethyl sulfide derived aerosol to marine CCN

Yoon

Brimblecombe

2002

Atmos. Chem. Phys.

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Abstract. The concentration of cloud condensation nuclei (CCN) in the marine boundary layer (MBL) was estimated from dimethyl sulfide (DMS) flux, sea salt (SS) emission, and aerosols entrained from the free troposphere (FT). Only under clean air conditions, did the nucleation of DMS derived sulfur (DMS CCN) contribute significantly to the MBL CCN. The accommodation coefficient for sulfuric acid mass transfer was found to be a very important parameter in the modeling the contribution of DMS to MBL CCN. The relationship between seawater DMS and MBL CCN was found to be non-linear mainly due to the transfer processes of sulfuric acid onto aerosols. In addition, sea salt derived CCN (SS CCN) and entrained aerosol from the FT (FT CCN) affected the MBL CCN directly, by supplying CCN, and indirectly, by behaving as an efficient sink for sulfuric acid. The SS CCN explained more than 50% of the total predicted MBL CCN when wind speeds were moderate and high. Sea salt and FT aerosol may often be more efficient sources of MBL CCN than DMS.

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“…Dickerson et al, 1987;Poulida et al, 1996). Since outflow of larger convective clouds has recently been suggested as a source for new particles, UCN measurements have been widely used to detect convective outflow (de Reus et al, 2001;Clarke et al, 1999;Wang et al, 2000). Three events during which the trace gas signatures indicate transport of boundary layer air into or above the tropopause region are marked in grey in Figs.…”

Section: Meteorological Situationmentioning

confidence: 99%

Deep convective injection of boundary layer air into the lowermost stratosphere at midlatitudes

et al. 2003

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Abstract.On 22 August 2001 a measurement flight was performed with the German research aircraft FALCON from Sardinia to Crete as part of the Mediterranean Oxidant Study (MINOS). Cruising at 8.2 km, the aircraft was forced to climb to 11.2 km over the southern tip of Italy to stay clear of the anvil of a large cumulonimbus tower. During ascent into the lowermost stratosphere in-situ measurements onboard the FALCON indicated several sharp increases in the concentrations of tropospheric trace gases, e.g. CO, acetone, methanol, benzene and acetonitrile, above the anvil. During one particular event deep in the stratosphere, at O 3 concentrations exceeding 200 ppv, CO increased from about 60 to 90 ppv, while the concentration of acetone and methanol increased by more than a factor of 2 (0.7 to 1.8 ppv for acetone; 0.4 to 1.4 ppv for methanol). Enhancements for the short lived species benzene are even higher, increasing from 20 pptv in the stratosphere to approx. 130 pptv. The concentrations during the event were higher than background concentrations in the upper troposphere, indicating that polluted boundary layer air was directly mixed into the lowermost stratosphere.

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Nucleation in the equatorial free troposphere: Favorable environments during PEM‐Tropics

Cited by 124 publications

References 34 publications

A global off-line model of size-resolved aerosol microphysics: I. Model development and prediction of aerosol properties

A global off-line model of size-resolved aerosol microphysics: I. Model development and prediction of aerosol properties

Modelling the contribution of sea salt and dimethyl sulfide derived aerosol to marine CCN

Deep convective injection of boundary layer air into the lowermost stratosphere at midlatitudes

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