Showing papers in "Tellus B in 1988"
TL;DR: Lidar measurements and airborne-particle collections were made during KOSARP 87 (KOSA) Research Program of Nagoya University; April-May 1987) at Nagoya (35°N, 137°E) to investigate the vertical distribution of Asian dust and the transport of these particles.
Abstract: Lidar measurements and airborne-particle collections were made during KOSARP 87 (‘KOSA’ Research Program of Nagoya University; April-May 1987) at Nagoya (35°N, 137°E) to investigate the vertical distribution of Asian dust (KOSA) particles and the transport of these particles. According to the lidar measurements, the highly concentrated particle layers with large depolarization ratio were frequently in the range from about 2 km to about 6 km. Electron microscope observations on the morphology of individual particles in the height range from near the ground to about 4400 m suggested that the particle layers contained many soil particles. It is reasonable to consider that KOSA particles were very frequently transported from Asian desert areas to the islands of Japan in the middle troposphere, even when the effect of the KOSA was not detected near the ground. This ‘background KOSA’ has concentrations of about 1.9 ~ 25 pg/m 3 at the layer peaks and one order of magnitude smaller than the values of severe KOSA. However, the contribution of the ‘weak KOSA’ to the global budget of soil particles is not negligible since the frequency of occurrence of ‘weak KOSA’ is high. The reaction of soil particles sampled on the vapour-deposited Ca thin-film suggested that some of the particles were coated by water or solution containing SO 2- 4 . Such particles can absorb various atmospheric gases, and therefore the KOSA particles can play an important role in the geochemical cycle of many chemical constituents, as chemical reaction sites in the atmosphere and as carriers of the chemical products. DOI: 10.1111/j.1600-0889.1988.tb00119.x
221 citations
TL;DR: In this paper, the carbon dioxide concentration has been measured in air samples collected approximately once per week at 22 globally distributed sites during 1981-84, and the selected data have been analyzed using an objective curve fitting method which enables improved estimation of uncertainties associated with derived parameters.
Abstract: The carbon dioxide concentration has been measured in air samples collected approximately once per week at 22 globally distributed sites during 1981-84. All samples were analyzed on the same non-dispersive infrared analyzer apparatus at the NOAA/GMCC laboratory in Boulder. The measured concentrations are directly traceable to the WMO primary C0 2 standards. Samples which do not contain well-mixed, regionally representative air or which have been contaminated during or subsequent to sampling, have been identified. The selected data have been analyzed using an objective curve fitting method which enables improved estimation of uncertainties associated with derived parameters. The latitudinal distribution of annual mean CO 2 concentration at the network sites shows significant interannual variability possibly related to the 1982-83 El Nino/Southern Oscillation event. No evidence was found for significant interannual variations or trends in the phase or amplitude of the seasonal cycle. Significant interannual and interstation variability in the CO 2 growth rate was observed. A growth rate minimum during 1982 was followed by a growth rate maximum in 1983, in association with the intense 1982-83 ENS0 event. The mean global growth rate for 1981-84 was 1.22 ppm yr -1 . DOI: 10.1111/j.1600-0889.1988.tb00214.x
180 citations
TL;DR: In this article, a general picture of the biogeochemical cycling of HCOOH and CH 3 COOH is beginning to emerge, and the similarity of concentrations in remote and impacted regions indicates that anthropogenic emissions of carboxylic acids or precursors are probably not important sources over broad geographic areas.
Abstract: Despite remaining uncertainties, a general picture of the biogeochemical cycling of HCOOH and CH 3 COOH is beginning to emerge. These acids are ubiquitous vapor- and aqueous-phase constituents of the global troposphere, contributing significant fractions of the natural acidity in precipitation and cloudwater, particularly in continental regions of the tropics and subtropics. The similarity of concentrations in remote and impacted regions indicates that anthropogenic emissions of carboxylic acids or precursors are probably not important sources over broad geographic areas. In continental regions, seasonally varying emissions of acids and hydrocarbon precursors from vegetation are thought to represent major sources for both acids. In marine areas, the seasonality of wet deposition and apparent lack of transport from continents support the hypothesis of a marine biogenic source. Ratios of total (aqueous + vapor) concentrations of HCOOH versus CH 3 COOH in clouds vary as a function of H + . This observation is consistent with the hypothesis of a pH-dependent aqueous-phase source and sink for HCOOH in clouds which may act to stabilize aqueous-phase ratios against shifts in solution Ht. Large die1 periodicities in the concentrations of vapor-phase species over continents, together with a lack of evidence for long-distance transport, suggest that HCOOH and CH 3 COOH experience short atmospheric lifetimes of several hours to a few (at most) days. Because they are important controllers of free acidity and represent a potentially large sink for aqueous-phase OH radicals, the cycling of the carboxylic acids is expected to interact directly and indirectly in the chemical cycling of other atmospheric constituents. DOI: 10.1111/j.1600-0889.1988.tb00106.x
173 citations
TL;DR: In this article, the influence of different atmospheric flow patterns on the composition of precipitation on the island of Bermuda was investigated using a cluster analysis of atmospherictrajectories to identify periods of similar transport.
Abstract: In an effort to investigate the influence of different atmospheric flow patterns on thecomposition of precipitation on the island of Bermuda, a cluster analysis of atmospherictrajectories was performed to identify periods of similar transport. The cluster analysistechnique represents a relatively objective alternative to the more subjective method ofclassifying trajectories according to compass sector. Data were stratified into two broadseasons, defined as a warm (April-September) and a cool (October-March) season. Relative tothe cool season, significantly higher per event concentrations of non-seasalt sulfate and nitrateoccurred in the warm season on Bermuda. There was no significant difference in the per eventprecipitation amount between seasons; however, there was significantly higher per eventdeposition of warm season non-seasalt sulfate, and nitrate. Significant differences inprecipitation composition were also identified between flow patterns. It was found that thesource regions which contributed the largest fraction of hydrogen ion deposition and nonseasaltsulfate deposition on Bermuda differed by season. During the cool months, 40% of thedeposition occurred with transport from the west, off the East Coast of the US, implicatinganthropogenic sources. In the warm season, an equally large fraction of deposition wasassociated with flow from the Bahamas region, suggesting an oceanic source of biogenic sulfuras the precursor. DOI: 10.1111/j.1600-0889.1988.tb00117.x
147 citations
TL;DR: In this article, the analysis of high-volume aerosol filters sampled continuously for nearly 5 years, concentration records of the following aerosol components are presented: (a) major ions (sea-salt, sulfate, nitrate); (b) cosmogenic 7 Be and terrigeneous 210 Pb; (c) trace elements (crustal Mn, heavy metal Pb).
Abstract: At the German Antarctic research station (70°S, 8°W), long-term observations of the chemical and radio-chemical composition of atmospheric particulate matter were started in spring 1983. Based on the analysis of high-volume aerosol filters sampled continuously for nearly 5 years, concentration records of the following aerosol components are presented here : (a) major ions (sea-salt, sulfate, nitrate); (b) cosmogenic 7 Be and terrigeneous 210 Pb; (c) trace elements (crustal Mn, heavy metal Pb). All species mentioned, with the exception of stable and radioactive Pb, show annual cycles. The maximum occurs in austral summer for 7 Be, sulfate, and crustal Mn. For sea-salt, however, the maximum is found in local autumn, and for nitrate in local spring. In local summer, the enhanced 7 Be to 210 Pb ratio is attributed to intenser large scale vertical mixing. The pattern of total sulfate seems to be controlled by the nss-sulfate production from marine organo-sulfur species during local summer, whereas in polar night, nss-sulfate shows very low or even negative concentration. Crustal aerosol (indicated by Mn) shows a mean summer contribution of 16 ng/SCM which exceeds the mean winter level by more than a factor of two. Based on a mean wash-out ratio of 0.27.10 6 observed for 210 Pb bearing aerosol particles, a Pb snow concentration of 3.0 pg/g is deduced from the mean air concentration of 11 pg/SCM. DOI: 10.1111/j.1600-0889.1988.tb00114.x
140 citations
TL;DR: In this article, chlorinated pesticide residues and PCBs were measured in air vapour and particulate phases, snow, ice and dissolved and particulating seawater fractions collected from the Canadian Ice Island off Axel Heiberg Island (81°N) in 1986.
Abstract: Chlorinated pesticide residues and PCB’s were measured in air vapour and particulate phases, snow, ice and dissolved and particulate seawater fractions collected from the Canadian Ice Island off Axel Heiberg Island (81°N) in 1986. Concentrations of the most abundant compounds (hexachlorocyclohexanes, a and y-HCH) were higher in air vapour and snow during May than in August consistent with the inferred seasonal maximum of Arctic haze. Cyclodienes (dieldrin, heptachlor epoxide, cis and trans-chlordane) and PCB’s (quantified as Aroclor 1254) associated with particles in snow and seawater were also present in highest concentrations in late spring. p,p’-DDT and o,p’ and p,p-DDE were detected associated with particles in air, snow and seawater but concentrations were below levels for accurate quantification. Concentrations of dissolved HCH’s in seawater in the uniformly mixed upper 50 m (4-5 ng 1 -1 ) decreased by an order-of-magnitude to 280 m depth. There were no significant differences in vertical profiles for the two sampling periods. Similarities in ratios of HCH and chlordane isomers in air, snow and seawater above 100 m imply that these compounds are transferred between environmental compartments without transformations. Lower ratios below 100 m indicate a different source or selective conversion of specific isomers. DOI: 10.1111/j.1600-0889.1988.tb00118.x
118 citations
TL;DR: The mass-particle size distributions of Na, Al, Cd, and Pb were determined from 17, 1-5 day, high-volume cascade impactor samples collected throughout the Western Mediterranean atmosphere between 1980 and 1983 as discussed by the authors.
Abstract: The mass-particle size distributions (MSDs) of Na, Al, Cd, and Pb were determined from 17, 1–5 day, high-volume cascade impactor samples collected throughout the Western Mediterranean atmosphere between 1980 and 1983. As expected, the mass median diameter (MMD) was the largest for Na, representative of sea-salt aerosol, with a median value of 5.9 μm. The median value for the MMD for Al, representative of mineral aerosol, was 2.8 μm. The smallest values of the MMD were found for pollution-derived elements, Cd and Pb: 0.7 μm. In most cases, the MSDs, for each of the elements, were log-normal. Total dry deposition velocities were calculated from the two-layer deposition model of Slinn and Slinn (1980) using three approaches: (i) by characterizing the distribution as a MMD, (ii) by considering the size distribution as directly given by the cascade impactor, (iii) by fitting the assumed log-normal distribution and dividing it into 100 successive intervals. The first approach appeared to give underestimates. The two other approaches yielded similar results for Cd and Pb, of the order of 0.05 cms -1 . For these elements, however, more than 20% of the total dry deposition flux was due to particles with diameters of 7.2 μm or greater (collected by impactor stage 1). For Na and Al, the third approach yielded values at least one order of magnitude higher than when using the two others. This clearly underlines the major role played by large particles in controlling the dry deposition of sea-salt and mineral aerosol particles. Direct measurements of Al dry deposition, made in 1985–1986 on the northwestern coast of Corsica, agree best with the values predicted by the third approach (mean calculated and measured values of 1.8 and 3.0 cm s -1 respectively). Scanning electron microscopy examinations of samples confirm that mineral aerosol particles with diameters of 10 μm or greater dominate the dry deposition flux. Preliminary data indicate that for mineral aerosol particles, this flux is, on a yearly basis, about half of the wet deposition flux. However cascade impactor data are not adequate to retrieve true mass-particle size distribution in the size range which controls dry deposition ( D > 7 μm), and this is shown to be the source for one order of magnitude uncertainties in dry deposition calculations. DOI: 10.1111/j.1600-0889.1989.tb00315.x
105 citations
TL;DR: In this article, the authors evaluated the predictive capabilities of the models with direct eddy correlation measurements of SO 2 and O 3 fluxes to a deciduous forest for both well-watered and water-stressed conditions and found that by increasing the degree of detail of the exchange-governing physical processes from the simple single laye,: model to the more detailed multi-layer models, the predictions of the deposition rates improved by 40-50% as determined from the root mean square error (rmse).
Abstract: 4 canopy models, representing the various classes of models that are currently used to estimate gaseous deposition to plant canopies are presented. The predictive capabilities of the models are evaluated with direct eddy correlation measurements of SO 2 and O 3 fluxes to a deciduous forest for both well-watered and water-stressed conditions. By increasing the degree of detail of the exchange-governing physical processes from the more simple single laye,: model to the more detailed multi-layer models, the predictions of the deposition rates improved by 40-50% as determined from the root mean square error (rmse). We also found by including the effect of water stress in the stomatal resistance formulations, the rmse of the predictions were decreased by generally 50% for the models that were examined. DOI: 10.1111/j.1600-0889.1988.tb00297.x
93 citations
TL;DR: A detailed analysis of the history of land-use change in the Soviet Union that included tree cutting and regrowth, oxidation of woody debris, decay of wood products, and clearing of lands for agricultural expansion showed that the net carbon flux between the USSR and the atmosphere resulting from these activities was approximately zero in 1980; that is, there was only a small net flux of 0.037 x 10 15 g carbon from the land to the atmosphere in that year as mentioned in this paper.
Abstract: A detailed analysis of the history of land-use change in the Soviet Union that included tree cutting and regrowth, oxidation of woody debris, decay of wood products, and clearing of lands for agricultural expansion showed that the net carbon flux between the USSR and the atmosphere resulting from these activities was approximately zero in 1980; that is, there was only a small net flux of 0.037 x 10 15 g carbon from the land to the atmosphere in that year. These results are in contrast with previous analyses that found the USSR to be a net carbon sink. In our analysis, we found that regrowth of forest vegetation following harvest, when considered alone, was responsible for an annual net storage in the USSR of about 0.136 x 10 15 g C for the period 1955-1975. a value intermediate between estimates derived from a previous analysis. This storage was balanced by a net release to the atmosphere of about the same amount of carbon from a variety of processes, including the oxidation of woody debris and decay of wood products. In 1980, the carbon flux between the land and the atmosphere due to land-use change throughout the entire northern hemisphere’s temperate and boreal systems was also small, as these systems accumulated only 0.025 x 10 15 g C that year. DOI: 10.1111/j.1600-0889.1988.tb00215.x
87 citations
TL;DR: In this paper, the same authors reported that the organic acids in the Po Valley fall-winter conditions seem to originate from anthropogenic processes and that the bulk sample pH might not be representative of the acidity of individual droplets in equilibrium with the gas phase.
Abstract: Concurrent gas and liquid phase organic acid measurements during radiation fog episodes are reported. Gas phase concentrations of HCOOH and CH 3 COOH exhibit large variations from the detection limit (5 nmol m -3 0.1 ppb) to 150 nmol m -3 (3.5 ppb). Liquid phase concentration ranges of 11-175 and 10-269 μM were observed for HCOOH and CH 3 COOH, respectively. Large deviations from Henry’s law equilibrium were observed for HCOOH when the pH of fog droplet solutions was above 5. Our hypothesis is that in this range, the bulk sample pH might not be representative of the acidity of individual droplets in equilibrium with the gas phase. The organic acids in the Po Valley fall-winter conditions seem to originate from anthropogenic processes. DOI: 10.1111/j.1600-0889.1988.tb00109.x
82 citations
TL;DR: In this article, a particle dry deposition parameterization is applied to a general circulation model to carry out a diagnostic study of global scale dry deposition velocities of ambient aerosols.
Abstract: A particle dry deposition parameterization is applied to a general circulation model to carry out a diagnostic study of global scale dry deposition velocities of ambient aerosols. Bulk deposition velocities are calculated for observed nuclei, accumulation, and coarse modes using two models, one with a more complete description of surface processes. Seasonal as well as diurnal effects are analyzed. The spatial and temporal variability of deposition velocities depends in a complex fashion on both microphysical (particle size and characteristics of the surface elements) and meteorological (surface wind speed and atmospheric stability near the surface) variables. For individual snapshots, mass-average dry deposition velocities are found to lie in the range of 0.01-0.2 cm/s for the nuclei mode. 0.001-0.05 cm/s for the accumulation mode, and 1.25-5 cm/s for the coarse mode. When averaged over long-term simulations, the corresponding values are 0.015-O. I5 cm/s, 0.0024.03 cm/s, and 1.25-3.5 cm/s, respectively. Averaged deposition velocities are larger over vegetated areas than over snow, bare ground, and ocean surfaces by a factor of about 1.5-3 and seem also to be sensitive to different vegetation types. Over oceans, the deposition rates tend to mainly correlate with the surface wind speed patterns. Over land areas, however, the effect of the surface thermal response to insolation on convective mixing in the boundary layer becomes important, especially in conditions of small mean solar zenith angle. In this case, the deposition velocity shows a marked diurnal trend, being larger during daytime than during nighttime by a factor of 1.5- 2.5. The seasonal variation of surface wind speed and insolation, thus, affects the deposition patterns. Diffusiophoresis related to water evaporation over ocean surfaces is shown to possibly play an important rde in inhibiting deposition of accumulation-mode particles. DOI: 10.1111/j.1600-0889.1988.tb00210.x
TL;DR: In this article, it is shown that, except in urban areas andparticularly in tropical areas, these ants may be a significant source of the formic acid found insome parts of the continental troposphere.
Abstract: Formic acid is a ubiquitous constituent of the atmospheric gas and of precipitation, but itssources and their fluxes are poorly understood. One source not previously examined, emissionsfrom formicine ants, IS assessed in this work, and it is shown that, except in urban areas andparticularly in tropical areas, these ants may be a significant source of the formic acid found insome parts of the continental troposphere. This process could thus provide a new example of apotentially strong interaction linking the biosphere and the atmosphere. DOI: 10.1111/j.1600-0889.1988.tb00107.x
TL;DR: In this paper, the authors used teflon/nylon filter packs to measure concentrations of nitrate (aerosol plus vapor), sulfate, ammonium, and calcium at three locations in China during October of 1985.
Abstract: We used teflon/nylon filter packs to measure concentrations of nitrate (aerosol plus vapor),sulfate, ammonium, and calcium at three locations in China during October of 1985. On theaverage, molar sulfate concentrations were less than twice the total nitrate concentrations.This small ratio is somewhat surprising, in view of the large amount of coal burning in China.In Beijing, calcium was the dominant cation, but at both the Xinglong AstronomicalObservatory (a rural northern China site) and Changsha (the capital city of Hunan Province,in the south), there was more ammonium ion than calcium in the aerosol. During a period ofnortherly winds at Xinglong, the concentrations were comparable to reported backgroundvalues fiom North America and Europe, suggesting that this may be a good site for studying.4sian continental background air. DOI: 10.1111/j.1600-0889.1988.tb00296.x
TL;DR: In this paper, a mass-spectrometric method for determining N2O/CO2 partial pressure ratios is discussed, and the results are in good agreement with those of Mook and van der Hoek.
Abstract: If CO2 is cryogenically separated from atmospheric air for mass-spectrometric isotope analysis, the presence of N2O simultaneously condensed makes it necessary to correct the isotope results. The corrections were experimentally determined by analyzing N2O-CO2 gas mixtures. The results are in good agreement with those of Mook and van der Hoek. A mass-spectrometric method for determining N2O/CO2 partial pressure ratios is discussed. During our experiments, we found that N2O can be produced in a Penning cold cathode manometer.
TL;DR: In this article, the authors measured the partial pressure of surface seawater to clarify its time and space variation in the western North Pacific, eastern Indian and Southern Ocean south of Australia during the Southern Cross Cruise in 1968, the BIOMASS Cruise in 1983/84 and the Ryofu-maru Cruises in 1984 and 1987.
Abstract: The partial pressure of carbon dioxide (pCO 2 ) in surface seawater was measured to clarify its time and space variation in the western North Pacific, eastern Indian and Southern Ocean south of Australia during the Southern Cross Cruise in 1968169, the BIOMASS Cruise in 1983/84 and the Ryofu-maru Cruises in 1984 and 1987. The pCO 2 in surface seawater was high in high latitudes, coastal and equatorial regions and low in the subtropics. The spatial variation of pCO 2 clearly reflects the general circulation of seawater, i.e., vertical mixing of seawater plays an important rijle in determining the pCO 2 in surface seawater. Two kinds of periodicities during the annual cycle, which are caused by the variations in seawater temperature, vertical mixing and biological activities, were found off Japan's coast. The pCO 2 in surface seawater obtained in the boreal winters of 1969 and 1984 suggests an increase due to the enhancement of CO 2 flux from air to sea. The apparent increase was 20.0 f 10.6 ppm in the western North Pacific, and 24.4 8.3 ppm in the Southern Ocean, south of Australia. DOI: 10.1111/j.1600-0889.1988.tb00300.x
TL;DR: A model for the isotopic composition of water vapor above the atmospheric boundary layer is presented in this article, which includes the effects of isotope fractionation and vertical turbulent transport of vapor.
Abstract: A model for the isotopic composition of water vapor above the atmospheric boundary layer ispresented. The model includes the effects of isotope fractionation and vertical turbulenttransport of vapor. It utilizes an assumed air trajectory in which an air parcel initially acquireswater vapor over the ocean, rises dry and then moist adiabatically. and finally sinks to theobserved conditions of height, temperature and dew point temperature. Discrepanciesbetween model predictions and actual profiles are shown to have characteristic signatureswhich render the isotopic composition of water vapor of potential value as a dynamic tracer ofatmospheric processes and motions. DOI: 10.1111/j.1600-0889.1988.tb00217.x
TL;DR: In this paper, the authors used a multichannel spectrometric detector to record the tropospheric hydroxyl (OH) absorption spectra, which can be used for registration and correction of overlapping absorption features of interfering trace gases.
Abstract: Tropospheric hydroxyl (OH) radical concentrations were measured in summer 1987 in Jiilich by broadband laser long-path absorption (laser-LPA) spectroscopy observing the Q 1 (2), Q 2 1 (2).Q 1 (3).Q 2 1 (3). and P 1 (1) rotational absorption lines around 308 nm. The measurement technique was improved using a multichannel spectrometric detector to record the OH absorption spectra. Now a much wider spectral interval can be observed at high resolution; thus, registration and correction of overlapping absorption features of interfering trace gases is improved. Simultaneous to the OH measurements, the concentrations of nitrogen dioxide (NO 2 ), formaldehyde (HCHO), and sulfur dioxide (SO 2 ) were monitored by a second LPA spectrometer. Ozone (O 3 aerosol concentrations, meteorological parameters, and absolutely calibrated photolysis frequencies of O 3 and NO 2 were also recorded. Carbon monoxide (CO), methane (CH 4 ), and light hydrocarbons were determined by gas chromatographic analysis. OH concentrations ranged up to 6.8.10 6 molecules/cm 3 . At one day in July, an 'asymmetric' diurnal profile of the OH concentration was observed, which could be qualitatively explained by a strong decrease in the NO 2 concentration during the morning hours. DOI: 10.1111/j.1600-0889.1988.tb00115.x
TL;DR: In this paper, the authors present a first application of a hemispheric transport model to quantitatively evaluate the spreading of the radioactive debris following the Chernobyl nuclear accident, which is essentially a simplified version of the Eulerian LRTAP Model described in Pudykiewicz et al. (1985).
Abstract: In this paper we present a first application of a hemispheric transport model to quantitatively evaluate the spreading of the radioactive debris following the Chernobyl nuclear accident. The model employed in the simulation is essentially a simplified version of the Eulerian LRTAP Model described in Pudykiewicz et al. (1985). Meteorological data driving the model were obtained from the standard CMC analysis. The accident scenario was estimated using general guidelines approved for analysis of nuclear emergencies. Results of the model simulation were verified against measurements for Stockholm, Helsinki, Halifax and Vancouver and indicate a relatively high level of agreement considering the simplicity of the approach.
TL;DR: The atmospheric behavior of PAN at locations well-removed from major urban areas has been studied over extended periods using highly sensitive, automated gas chromatographic techniques at two sites in eastern Canada; Longwoods in southern Ontario (February-actober 1983), and Kejimkujik in Nova Scotia (May 1984 onwards).
Abstract: The atmospheric behaviour of PAN at locations well-removed from major urban areas has been studied over extended periods using highly sensitive, automated gas chromatographic techniques at two sites in eastern Canada; Longwoods in southern Ontario (Februaryactober 1983), and Kejimkujik in Nova Scotia (May 1984 onwards). In addition, data have also been obtained from more limited measurement programs in northern Ontario at Chalk River (November-December 1983) and North Bay (January-February 1984). The variations in PAN mixing ratios observed at these sites have been examined with reference to available data for other atmospheric components, such as O 3 , HNO 3 , particulate nitrate and sulphate. Air mass back-trajectory calculations have been performed for Kejimkujik to relate observed periods of elevated PAN mixing ratio to specific source regions for precursor NMHC and NO x . For the sites studied, periods of enhanced PAN mixing ratio are observed to be possible throughout the yearly cycle, indicating that significant photochemical activity can occur even during wintertime. This contrasts with the available data for ozone, where photochemical formation in polluted air masses appears to be suppressed in winter. Seasonal patterns of PAN behaviour are probably sitedependent, but the observations suggest that the highest PAN maxima are favoured during fall and late winter/early spring. The long-term data from Kejimkujik also reveal an underlying seasonal variation in the typical background value of PAN observed at this site; this background value maximizes in late winter/early spring and minimizes in summer. In general, the magnitude of the observed PAN maxima appears to decrease with distance from the source region of influence. PAN accounts for a significant fraction of the observed oxidized nitrogen species at all the sites studied, and appears to make an increasing contribution as the transport time from the source region increases. In background tropospheric air, the contribution of PAN may be as high as 80-90%. DOI: 10.1111/j.1600-0889.1988.tb00113.x
TL;DR: In this article, a review of available precipitation sulfate data from the North Atlantic and adjacent coastal regions yields a concentration field which is consistent with known source distributions and meteorological factors.
Abstract: This paper examines the transport of North American sulfur emissions across the North Atlantic Ocean to Europe. A review of available precipitation sulfate data from the North Atlantic and adjacent coastal regions yields a concentration field which is consistent with known source distributions and meteorological factors. The marine background precipitation excess sulfate concentration is found to be 6-8 μeq 1 -1 and [SO 4 = ] to decrease from >50 μeq 1 -1 with offshore flows at the North American east coast to 8-15 μeq 1 -1 with onshore flows at the European west coast. This decay is consistent with a distance constant of 2400 km and a residence time of ~80 h, and in turn, corresponds to a transatlantic flux of anthropogenic sulfur of 0.3-0.4 Tg a -1 . A second independent estimate, based on the application of a climatological dispersion model, which accounts for long-term average diffusion, wet and dry deposition, and SO 2 to SO 4 = transformation, yields a flux of North American anthropogenic sulfur at the European west coast of 0.2 Tg a -1 , in agreement with the first estimate. At the distance of the European west coast, North American anthropogenic emissions account for ca. 4 μeq S 1 -1 in precipitation-less than the marine background of 6-8 μeq 1 -1 , and much less than the annual average [SO 4 = ] value of ca. 30 μeq S 1 -1 appropriate for much of the coastal region. It is concluded that, on average, the amount of North American anthropogenic sulfur reaching Europe is small compared to that from other sources. DOI: 10.1111/j.1600-0889.1988.tb00208.x
TL;DR: The relative importance of dry and wet deposition of sulphate and nitrate over southeastern Canada is examined using daily air and precipitation chemistry observations made at 6 rural stations of the Air and Precipitation Monitoring Network (APN) during the period 1979 to 1982 as discussed by the authors.
Abstract: The relative importance of dry and wet deposition of sulphate and nitrate over southeastern Canada is examined using daily air and precipitation chemistry observations made at 6 rural stations of the Air and Precipitation Monitoring Network (APN) during the period 1979 to 1982 Dry deposition was calculated from these air concentrations using deposition velocity information on land-use types, on atmospheric wind speed and stability and on dry deposition rates from over 80 published studies Despite the large uncertainty in dry deposition estimates which is associated with the complexity of the process, valuable conclusions emerge It is estimated that total annual deposition varies between 10 to 86 mmole m −2 and 13 to 62 mmole m −2 for SO = 4 and NO - 3 , respectively To eastern Canada 22% and 30% of the total SO=4 and NO−3 deposition is dry deposited, respectively Depending on location, the contribution of SO2 to the dry deposition of sulphur ranges from 37% to 78% It tends to decrease with increasing distance from major sources In eastern Canada, the best estimate of the fraction of the total dry deposition of nitrogen contributed by NO2 and HNO3 is in the range 50% to 60% and 31 % to 45%, respectively, depending on location The uncertainty in the NO2 estimate is large, approaching a factor of 35 Even if PAN dry deposition velocities are equal to that of NO 2 (they are expected to be lower), the contribution of PAN to total nitrate deposition is negligibly small Both dry and wet deposition are episodic in nature It is estimated that the top-20% deposition events yield 47% to 70% of the total deposition DOI: 101111/j1600-08891988tb00213x
TL;DR: In this paper, the authors show that following this type of analysis procedure can lead to the interpretation of coefficients as being physically significant, when they are purely noise, and several checks to avoid such a pitfall are suggested.
Abstract: Owing to the complex nature of eigenanalysis programming algorithms, most atmospheric science research utilizing empirical orthogonal functions (EOFs), principal component analysis (PCA), or common-factor analysis (CFA) use the “canned” computer programs on statistical packages such as EISPACK, IMSL, SAS, BMDP, etc. These programs usually encourage truncation of the eigenvector series according to some criterion to exclude noise and facilitate data reduction; the EOFs/PCs/CFs retained are then often physically interpreted (with or without further linear transformations) according to which variables have salient magnitudes. Results presented here illustrate that following this type of analysis procedure can lead to the interpretation of coefficients as being physically significant, when they are purely noise. Several checks to avoid such a pitfall are suggested.
TL;DR: In this paper, it was shown that high local wind speeds prove to be a major determinant of data quality: extremely high seasalt loadings (average rainwater sodium and chloride concentrations in the low millimolar range) make estimation of excess sulfate impossible against a background sulfate concentration of about 150 μ eq/l derived from sea-salt.
Abstract: Rainwater composition data resulting from monthly, wet-only collections of maritime rain at Cape Grim, Australia, in the period April 1977 to March 1985 have been critically appraised. High local wind speeds prove to be a major determinant of data quality: extremely high seasalt loadings (average rainwater sodium and chloride concentrations in the low millimolar range) make estimation of excess sulfate impossible against a background sulfate concentration of about 150 μeq/l derived from sea-salt. The extreme wind speeds also cause considerable erosion of the Cape surface, leading to the ubiquitous presence of local soil components in collected rainwater. Both the rainwater data and data from the analysis of local soil samples show that these soil components significantly elevate rainwater pH (observed mean 6.01) and the concentrations of potassium and calcium. Effects upon other ions appear to be minimal, but cannot be ruled out. Calculation of pH for rainwater having the long-term mean composition, but with the effects of local contamination excluded, yielded a value of 5.10. Further calculations in which sea-salt content of the rainwater was varied over the range observed at Cape Grim indicated that at this site, sea-salt alkalinity may be a major determinant of rainwater pH, leading to pH variations from 6. DOI: 10.1111/j.1600-0889.1988.tb00299.x
TL;DR: In this article, the acid content of aerosol particles was characterized by buffer capacity titrations, and organic acids were determined by HPLC, with the highest concentrations occurring during a winter-time smog period.
Abstract: During fall and winter 1986/87, aerosol samples were collected with a 5-stage impactor in an urban, a suburban, and a rural area in Central Europe. The weak acid content of aerosol particles was characterized by buffer capacity titrations, and organic acids were determined by HPLC. C 4 -C 6 dicarboxylic acids were found to be the main constituents of aerosol organic acids, with the highest concentrations occurring during a winter-time smog period. Size distributions of single species showed a maximum in the accumulation mode, indicating that these compounds have gaseous precursors. It is suggested that these precursors are of anthropogenic origin. DOI: 10.1111/j.1600-0889.1988.tb00108.x
TL;DR: In this article, an explicit chemical reaction mechanism developed for use in tropospheric photochemical models was used to study the formation of organic nitrate species in an urban setting for a range of hydrocarbon to NO x ratios.
Abstract: The transformation of nitrogen oxide was investigated using an explicit chemical reaction mechanism developed for use in tropospheric photochemical models. Through box-model simulations, the mechanism was first used to study the formation of organic nitrate species in an urban setting for a range of hydrocarbon to NO x ratios. Next, several changes to the basic mechanism were incorporated to study their effect on organic nitrate formation. The results show organic nitrates are present and their amounts depend on the ratio of hydrocarbons to NO x . At high HC/NO x ratios, as much as 24% of the nitrogen emitted into an urban area may be transformed to organic nitrates. Experimental evidence on the yields and rates of some reactions is scarce. DOI: 10.1111/j.1600-0889.1988.tb00111.x
TL;DR: In this paper, aluminum and sea salt aerosol samples were collected for 6 months from 25 November 1984 at Okushiri Island in the Japan Sea and analyzed for aluminum and salt.
Abstract: Daily aerosol samples were collected for 6 months from 25 November 1984 at Okushiri Island in the Japan Sea. The samples were analyzed for aluminum (an indicator of mineral aerosol) and sodium (an indicator of sea salt aerosol), and the following results and conclusions were obtained. The atmospheric concentration of aluminum was higher in spring than winter, while the concentration of sodium in winter decreased toward spring. The concentration of sodium was positively correlated with westerly wind force but the concentration of aluminum was not correlated with the wind force. According to a harmonic analysis of the observed data, the Concentration of aluminum showed a 4-day periodicity, but we could not find any remarkable periodicity for sodium. These results suggest that the mineral aerosols in the surface air over the Japan Sea were transported across a long distance, probably from the arid regions of the Asian continent with continental air masses changing its direction gradually, and that a large amount of sea salt aerosol is produced in the Japan Sea during the winter monsoon and transported directly to the coastal area along the Japan Sea. DOI: 10.1111/j.1600-0889.1988.tb00211.x
TL;DR: In this paper, a three-dimensional, Eulerian modeling system was used to study transport of chemical species from North America and Europe to the Atlantic Ocean, where plumes were intermittently found moving out over the ocean from the continental source region.
Abstract: A three-dimensional, Eulerian modeling system was used to study transport of chemical species from North America and Europe to the Atlantic Ocean. A mesoscale meteorological model simulated April 1982 with 10 consecutive 3-day runs. This simulated meteorology drove a chemical model with 24 predicted and transported species, and 11 non-transported (photochemical equilibrium) species. We used artificially clean initial and boundary conditions to investigate the effect of anthropogenic emissions on ozone. Two weeks were needed to “spin up” the chemical model. At individual times, plumes were intermittently found moving out over the ocean from the continental source region. In the planetary boundary layer, the time-average plumes were significantly weakened by vertical transport and aqueous chemistry in clouds. The continental plume of Europe was often more persistent than that from North America. The simulated total fluxes of sulfur (S) and nitrogen (N) from North America to the Atlantic Ocean, in a layer from the surface to 5.5 km high, were in reasonable agreement with data analyses. The eastward, atmospheric flux of S was 4.8 Tg/yr and that of N was 1.8 Tg/yr. DOI: 10.1111/j.1600-0889.1988.tb00110.x
TL;DR: In this paper, the trace elemental composition of atmospheric aerosols was investigated at three rural locations in eastern Canada during the autumn of 1984 using air parcel back-trajectories, multivariate analysis, and lead isotope ratios.
Abstract: Measurements of the trace elemental composition of atmospheric aerosols were undertaken at three rural locations in eastern Canada during the autumn of 1984. One aim was to investigate differences in anthropogenic elemental composition between aerosols of regional eastern North American origin and “background” aerosols in air masses moving into the region. Another aim was to identify the origin of aerosol trace elements with the use of air parcel back-trajectories, multivariate analysis, and lead isotope ratios. Daily aerosol samples taken at Dorset Ontario, For& Montmorency Quebec, and Kejimkujik Nova Scotia, were analyzed by instrumental neutron activation analysis and inductively-coupled plasma mass spectrometry for Ti, Br, Mn, In, Na, V, Al, Ca, Se, As, Sb, Pb, Cd, and Pb-206/207 isotope ratios. Average concentrations of Na and V showed the greatest regional diversity and were 8.0 and 5.4 times higher at Kejimkujik than at Dorset, respectively. Factor analysis revealed the presence of a soil, a marine, and a general pollution component in the aerosols, plus additional components specific for a few elements of anthropogenic origin. Cornparison of mean concentrations in samples grouped by similarity of the associated back-trajectories showed that In and As were excellent tracers of non-ferrous smelter emissions. Trajectories from prominent coal-burning areas were also enriched in As but were associated with low In concentrations. Groups of trajectories originating from background areas, i.e., without major anthropogenic sources of aerosols, formed a significant fraction of the samples and accounted for 20%-25% of the classified aerosol samples at each site. Comparison of the mean concentrations in the background groups with each other and with similar aerosol data from the Arctic showed that both local influences, such as the composition of soils in the immediate area, and long-range transport of aerosols can affect the apparent local composition of the background aerosol. Using recent findings by Sturges and Barrie that there is a significant difference between the Pb isotope ratio in aerosols from smelters, Canadian auto exhaust and American sources, the fraction of Pb originating from each source was estimated for each location. During the 3-month period studied, it is estimated that Pb from automotive emissions in the US accounted for 46%, 28%, and 44% of the atmospheric Pb at Dorset, For& Montmorency, and Kejimkujik, respectively, versus 52%, 67%, and 51% from Canadian auto exhaust. DOI: 10.1111/j.1600-0889.1988.tb00116.x
TL;DR: In this paper, a simple model is advanced to explain Junge's empirical result relating the residence times of trace gases in the troposphere to a coefficient of deviation of their concentrations, which can be derived from a peculiar definition for the concentration variations inspace, based only on the spatial variation of the mean concentration.
Abstract: A simple model is advanced to explain Junge’s empirical result relating the residence times oftrace gases in the troposphere to a coefficient of deviation of their concentrations. It is shownthat Junge’s result can be derived from a peculiar definition for the concentration variations inspace, based only on the spatial variation of the mean concentration. Nevertheless, forsufficiently uniform sources and sinks of the gases, the result can be used to estimatetropospheric residence-times of gases, if account is taken for the interval sampled. DOI: 10.1111/j.1600-0889.1988.tb00292.x
TL;DR: In this article, the authors used 2 years of data on the composition of precipitation at two locations on Bermuda, and found that enrichments of sea-salt in Bermuda precipitation, relative to open ocean precipitation, can occur due to ocean-island turbulence.
Abstract: The understanding of atmospheric biogeochemical cycles in marine areas depends heavily on the collection and analysis of precipitation samples. However, collection of marine precipitation is difficult due to constraints on sampling locations. For example, the island of Bermuda has been used to characterize the composition of precipitation over the western north Atlantic Ocean. However, Bermuda is a small, heavily populated island and the possibility exists that local processes can influence the composition of precipitation. Using 2 years of data on the composition of precipitation at 2 locations on Bermuda, this paper documents that enrichments of sea-salt in Bermuda precipitation, relative to open ocean precipitation, can occur due to ocean-island turbulence. Smaller enrichments of non-sea-salt (nss) Ca ++ , nss SO = 4 , NH + 4 and H + are also observed. At present it is not possible to determine whether the enrichments are due to island sources or spatial variability in the precipitation scavenging process. By assuming the latter effect to be negligible, the upper limits of the effect of island sources on the concentrations of the nss components (Ca ++ , SO = 4 , NO - 3 , H + ) are ~ 5-30%, depending on the species. Precipitation associated with westerly airflow is the least affected by local sources. DOI: 10.1111/j.1600-0889.1988.tb00288.x