The thermodynamics of pollutant removal as an indicator of possible source areas for arctic haze

Bowling, Sue Ann; Shaw, Glenn E.

doi:10.1016/0960-1686(92)90287-u

Cited by 17 publications

(10 citation statements)

References 19 publications

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“…Previous studies using the same host chemical transport model (TOMCAT) have not revealed any major global discrepancy in wet deposition [Giannakopoulos et al, 1999;Rasch et al, 2000], but the Arctic appears to present a particularly severe test of the model wet removal scheme because it is remote from strong aerosol sources so aerosol abundance becomes dominated by removal processes. Bowling and Shaw [1992] discussed the difficulty of reconciling basic thermodynamic changes in air transported to the Arctic with the survival of air pollutants. They showed that the observed temperature and humidity of polluted Arctic air could only be explained if precipitation occurred during transport or if pollutants were injected high into dry layers at source.…”

Section: Discussionmentioning

confidence: 99%

A global model study of processes controlling aerosol size distributions in the Arctic spring and summer

Korhonen¹,

Carslaw²,

Spracklen³

et al. 2008

J. Geophys. Res.

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[1] We use a global chemical transport model (CTM) with size-resolved aerosol microphysics to evaluate our understanding of the processes that control Arctic aerosol, focussing on the seasonal changes in the particle size distribution during the transition from Arctic haze in spring to cleaner conditions in summer. This period presents several challenges for a global model simulation because of changes in meteorology, which affect transport pathways and precipitation scavenging rates, changes in the ocean-atmosphere flux of trace gases and particulates associated with sea ice break-up and increased biological activity, and changes in photolysis and oxidation rates which can affect particle nucleation and growth rates. Observations show that these changes result in a transition from an accumulation mode-dominated aerosol in spring to one dominated by Aitken and nucleation mode particles in summer. We find that remote Arctic aerosol size distribution is very sensitive to the model treatment of wet removal. In order to simulate the high accumulation mode concentrations typical of winter and spring it was necessary to substantially reduce the scavenging of these particles during transport. The resulting increases in accumulation mode lead to improvement in the modeled Aitken mode particle concentrations (which fall, due to increased scavenging in the free troposphere) and produce aerosol optical depths in good agreement with observations. The summertime increase in nucleation and Aitken mode particles is consistent with changes in local aerosol nucleation rates driven mainly by increased photochemical production of sulphuric acid vapor and, to a lesser extent, by decreases in the condensation sink as Arctic haze decreases. Alternatively, to explain the observed summertime Aitken mode particle concentrations in terms of ultrafine sea spray particles requires a sea-air flux a factor 5-25 greater than predicted by current wind speed and sea surface temperature dependent flux parameterizations. The enhanced total flux is clearly higher than measured in the Arctic and cannot explain the observed nucleation mode in the high Arctic. The model suggests that the summertime source of Aitken particles has very little effect on the accumulation mode and aerosol optical depth but they may contribute to cloud condensation nuclei in clouds with updraught velocities greater than about 15 cm/s. From a global aerosol modeling perspective, our understanding of Arctic aerosol is poor. We suggest several processes that currently limit our ability to simulate this challenging environment.

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Section: Discussionmentioning

confidence: 99%

A global model study of processes controlling aerosol size distributions in the Arctic spring and summer

Korhonen¹,

Carslaw²,

Spracklen³

et al. 2008

J. Geophys. Res.

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“…During transport from the source regions to the Arctic, the pollutant‐containing air masses have a high probability of reaching saturation and nucleating and precipitating clouds. It is not understood how so much material gets through a strongly scavenging system (Bowling and Shaw, 1992).…”

Section: The Arctic Haze Phenomenonmentioning

confidence: 99%

Comparison of the radiative properties and direct radiative effect of aerosols from a global aerosol model and remote sensing data over ocean

Myhre

Bellouin

Berglen

et al. 2007

Tellus B: Chemical and Physical Meteorology

303

194

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T E L L U SComparison of the radiative properties and direct radiative effect of aerosols from a global aerosol model and remote sensing data over ocean A B S T R A C T A global aerosol transport model (Oslo CTM2) with main aerosol components included is compared to five satellite retrievals of aerosol optical depth (AOD) and one data set of the satellite-derived radiative effect of aerosols. The model is driven with meteorological data for the period November 1996 to June 1997 which is the time period investigated in this study. The modelled AOD is within the range of the AOD from the various satellite retrievals over oceanic regions. The direct radiative effect of the aerosols as well as the atmospheric absorption by aerosols are in both cases found to be of the order of 20 Wm −2 in certain regions in both the satellite-derived and the modelled estimates as a mean over the period studied. Satellite and model data exhibit similar patterns of aerosol optical depth, radiative effect of aerosols, and atmospheric absorption of the aerosols. Recently published results show that global aerosol models have a tendency to underestimate the magnitude of the clear-sky direct radiative effect of aerosols over ocean compared to satellite-derived estimates. However, this is only to a small extent the case with the Oslo CTM2. The global mean direct radiative effect of aerosols over ocean is modelled with the Oslo CTM2 to be -5.5 Wm −2 and the atmospheric aerosol absorption 1.5 Wm −2 .

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“…The range of Pb isotope composition defined by our high‐Pb points and by most of the data of Rosman et al [1993, 1994] is instead very similar to the mean composition of 1990 Arctic haze aerosols sampled in Barrow, Alaska [ Sturges et al , 1993] (Figure 5) and to aerosols collected in 1983–1984 for two Canadian high Arctic stations ( 206 Pb/ 207 Pb only [ Sturges and Barrie , 1989]). Chemical evidence [ Lowenthal and Rahn , 1985; Maenhaut et al , 1989; Nriagu , 1989a; Rahn , 1985] and meteorological investigations [ Bowling and Shaw , 1992; Iversen and Joranger , 1985; Raatz , 1991] point to the former Soviet Union as the dominant contributor to low‐altitude pollution in the Arctic vortex, with a lesser fraction from western European sources and negligible Canadian and U.S. contributions. For Pb in particular, a chemical transport model for 1979–1980 concluded that Pb flux to the Arctic during that year was split roughly equally between western European, eastern European, and former Soviet emissions sources (North American sources were not considered [ Akeredolu et al , 1994]).…”

Section: Sources Of Trace Metals In Central Greenlandmentioning

confidence: 99%

Temporal variability of Cd, Pb, and Pb isotope deposition in central Greenland snow

Sherrell

Boyle

Falkner

et al. 2000

Geochem Geophys Geosyst

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[1] We present a decade-long (1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990) high-resolution (subseasonal) record of Pb and Cd concentrations and Pb isotopic composition in a series of 119 snow samples from a 6-m snow pit at Summit, Greenland. Both metals show order of magnitude seasonal variability, with maxima in spring of every year, coinciding with sulfate peaks. These short-term features complicate attempts to quantify secular decadal-scale trends associated with anthropogenic source changes (e.g., phasing out of leaded gasoline). A small (<50%) decrease during the decade is estimated for Pb, but no significant trend is observed for Cd. Mean concentrations for the snow pit (Pb = 216, Cd = 11 pmol kg À1 ) are indistinguishable from mean values for nearly continuous samples of the 1-6 m section of a firn core drilled 1 km away, suggesting freedom from contamination artifact. An evaluation of potential sources confirms that Pb and Cd are dominated by anthropogenic inputs. Isotopic ratios ( 206 Pb/ 207 Pb and 208 Pb/ 207 Pb) determined on a subset of snow pit samples of varying ages within the decade indicate that springtime Pb concentration maxima are consistent with a mixture of eastern European, former Soviet Union, and western European sources, while seasonal Pb minima, especially from the early portion of the decade, plot along a different mixing line, suggesting a mixture of U.S. and European sources. The combination of Pb concentration and isotopic composition are consistent with an estimated decrease in U.S. Pb contributions of about twofold over the decade, which predicts a decadal concentration decrease in the snow of $30%. However, the secular trends in both concentration and isotopes are barely detectable against seasonal and interannual variability. The evidence for seasonally distinct source regions may be useful for interpretation of high-resolution records of other chemical species in Greenland snow and ice. Analyses of two deep core sections dated at 1699-1700 and 1780-1788, compared to the snow pit data, indicate that both Pb and Cd deposition in central Greenland roughly doubled during the eighteenth century, then doubled again by the 1980s.

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The thermodynamics of pollutant removal as an indicator of possible source areas for arctic haze

Cited by 17 publications

References 19 publications

A global model study of processes controlling aerosol size distributions in the Arctic spring and summer

A global model study of processes controlling aerosol size distributions in the Arctic spring and summer

Comparison of the radiative properties and direct radiative effect of aerosols from a global aerosol model and remote sensing data over ocean

Temporal variability of Cd, Pb, and Pb isotope deposition in central Greenland snow

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