Pub Date : 2001-11-01DOI: 10.1034/J.1600-0889.2001.530501.X
G. Whiting, J. Chanton
{"title":"Greenhouse carbon balance of wetlands: methane emission versus carbon sequestration: Greenhouse carbon balance of wetlands","authors":"G. Whiting, J. Chanton","doi":"10.1034/J.1600-0889.2001.530501.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2001.530501.X","url":null,"abstract":"","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":"428 1","pages":"521-528"},"PeriodicalIF":2.3,"publicationDate":"2001-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76489233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-09-01DOI: 10.1034/J.1600-0889.2000.00099.X
H. G. Wallraff, M. Andreae
Numerous experiments with homing pigeons and other birds strongly suggest that birds displaced to unfamiliar remote areas are able to determine their position relative to home by deducing relevant information from atmospheric trace gases perceived by olfaction. These findings induced the hypothesis that ratios between several airborne compounds show roughly monotonic spatial gradients, differently in different directions, over distances of some hundreds of kilometres. To test this hypothesis, 192 air samples were collected, successively in 3 summers, at 96 sites regularly distributed over an area covering a radius of 200 km around Wurzburg, Germany. Statistical analysis of the gas chromatographic measurements on these samples revealed that such gradients in the ratios between a number of omnipresent hydrocarbons do in fact exist. The gradients are noisy, but not beyond the range that is compatible with the homing behaviour of pigeons which is noisy as well. The directions of the gradients are remarkably robust against changes of weather, especially of winds. Winds, however, shift the levels of ratios in the whole area without dramatically changing the directional relationships. A systematic angular correlation between variations in space and variations caused by winds could theoretically be utilized by birds for navigational purposes. Our analysis dealt mainly with the most abundant anthropogenic hydrocarbons, which are the best-suited tracers to detect spatio-temporal distribution patterns. It is very likely that equivalent patterns exist in naturally emitted volatile compounds as well, given that they are subject to similar variability in the distribution of sources and sinks and similar transport patterns. DOI: 10.1034/j.1600-0889.2000.00099.x
{"title":"Spatial gradients in ratios of atmospheric trace gases : a study stimulated by experiments on bird navigation","authors":"H. G. Wallraff, M. Andreae","doi":"10.1034/J.1600-0889.2000.00099.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.00099.X","url":null,"abstract":"Numerous experiments with homing pigeons and other birds strongly suggest that birds displaced to unfamiliar remote areas are able to determine their position relative to home by deducing relevant information from atmospheric trace gases perceived by olfaction. These findings induced the hypothesis that ratios between several airborne compounds show roughly monotonic spatial gradients, differently in different directions, over distances of some hundreds of kilometres. To test this hypothesis, 192 air samples were collected, successively in 3 summers, at 96 sites regularly distributed over an area covering a radius of 200 km around Wurzburg, Germany. Statistical analysis of the gas chromatographic measurements on these samples revealed that such gradients in the ratios between a number of omnipresent hydrocarbons do in fact exist. The gradients are noisy, but not beyond the range that is compatible with the homing behaviour of pigeons which is noisy as well. The directions of the gradients are remarkably robust against changes of weather, especially of winds. Winds, however, shift the levels of ratios in the whole area without dramatically changing the directional relationships. A systematic angular correlation between variations in space and variations caused by winds could theoretically be utilized by birds for navigational purposes. Our analysis dealt mainly with the most abundant anthropogenic hydrocarbons, which are the best-suited tracers to detect spatio-temporal distribution patterns. It is very likely that equivalent patterns exist in naturally emitted volatile compounds as well, given that they are subject to similar variability in the distribution of sources and sinks and similar transport patterns. DOI: 10.1034/j.1600-0889.2000.00099.x","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":"20 1","pages":"1138-1157"},"PeriodicalIF":2.3,"publicationDate":"2000-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85905814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-06-01DOI: 10.1034/J.1600-0889.2000.D01-1.X
W. Schüssler, R. Neubert, I. Levin, N. Fischer, C. Sonntag
The amounts of microbial and root-respired CO 2 in a maize/winter wheat agricultural system in south western Germany were investigated by measurements of the CO 2 mixing ratio and the 13 C/ 12 C ratio in soil air. CO 2 fluxes at the soil surface for the period of investigation (1993–1995) were also determined. Root respired CO 2 shows a strong correlation with the plant mass above ground surface of the respective vegetation (R 2 ≥0.88); the maximum CO 2 release from roots was in August for the maize (2.0±0.5 mmol m −2 h −1 ) and in June for winter wheat (1.5±0.5 mmol m −2 h −1 ). Maximum CO 2 production by roots correlate well with the maximum amount of plant root matter. Integrating the CO 2 production over the whole growing season and normalizing to the dry root matter yields, the CO 2 production per gram dry organic root matter (DORM) of maize was found to be 0.14±0.03 gC (g DORM) −1 . At the sites investigated, root-produced CO 2 contributed (16±4)% for maize, and (24±4)% for winter wheat, respectively, to the total annual CO 2 production in the soil (450±50 gC m −2 for maize, 210±30 gC m −2 for winter wheat). DOI: 10.1034/j.1600-0889.2000.d01-1.x
{"title":"Determination of microbial versus root-produced CO2 in an agricultural ecosystem by means of δ13CO2 measurements in soil air","authors":"W. Schüssler, R. Neubert, I. Levin, N. Fischer, C. Sonntag","doi":"10.1034/J.1600-0889.2000.D01-1.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.D01-1.X","url":null,"abstract":"The amounts of microbial and root-respired CO 2 in a maize/winter wheat agricultural system in south western Germany were investigated by measurements of the CO 2 mixing ratio and the 13 C/ 12 C ratio in soil air. CO 2 fluxes at the soil surface for the period of investigation (1993–1995) were also determined. Root respired CO 2 shows a strong correlation with the plant mass above ground surface of the respective vegetation (R 2 ≥0.88); the maximum CO 2 release from roots was in August for the maize (2.0±0.5 mmol m −2 h −1 ) and in June for winter wheat (1.5±0.5 mmol m −2 h −1 ). Maximum CO 2 production by roots correlate well with the maximum amount of plant root matter. Integrating the CO 2 production over the whole growing season and normalizing to the dry root matter yields, the CO 2 production per gram dry organic root matter (DORM) of maize was found to be 0.14±0.03 gC (g DORM) −1 . At the sites investigated, root-produced CO 2 contributed (16±4)% for maize, and (24±4)% for winter wheat, respectively, to the total annual CO 2 production in the soil (450±50 gC m −2 for maize, 210±30 gC m −2 for winter wheat). DOI: 10.1034/j.1600-0889.2000.d01-1.x","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":"59 1","pages":"909-918"},"PeriodicalIF":2.3,"publicationDate":"2000-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85529771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-04-01DOI: 10.1034/J.1600-0889.2000.00076.X
H. Pawłowska, J. Brenguier
Microphysical measurements performed during 8 flights of the CLOUDYCOLUMN component of ACE-2, with the Meteo-France Merlin-IV, are analyzed in terms of droplet number concentration and size. The droplet concentration is dependent upon the aerosol properties within the boundary layer. Its mean value over a flight varies from 55 cm−3, for the cleanest conditions, to 244 cm−3, for the most polluted one. For each flight, the variability of the concentration, in selected cloud regions that are not affected by mixing with dry air or drizzle scavenging, ranges from 0.5 to 1.5 of the mean value. The mean volume diameter increases with altitude above cloud base according to the adiabatic cloud model. The frequency distribution of mean droplet volume normalized by the adiabatic value, for the selected regions, shows the same dispersion as the distribution of normalized concentration. The values of droplet concentration versus mean volume diameter are then examined in sub-adiabatic samples to characterize the effects of mixing and drizzle scavenging. Finally, the ratio of mean volume diameter to effective diameter is analyzed and a simple relationship between these 2 crucial parameters is proposed.
{"title":"Microphysical properties of stratocumulus clouds during ACE‐2","authors":"H. Pawłowska, J. Brenguier","doi":"10.1034/J.1600-0889.2000.00076.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.00076.X","url":null,"abstract":"Microphysical measurements performed during 8 flights of the CLOUDYCOLUMN component of ACE-2, with the Meteo-France Merlin-IV, are analyzed in terms of droplet number concentration and size. The droplet concentration is dependent upon the aerosol properties within the boundary layer. Its mean value over a flight varies from 55 cm−3, for the cleanest conditions, to 244 cm−3, for the most polluted one. For each flight, the variability of the concentration, in selected cloud regions that are not affected by mixing with dry air or drizzle scavenging, ranges from 0.5 to 1.5 of the mean value. The mean volume diameter increases with altitude above cloud base according to the adiabatic cloud model. The frequency distribution of mean droplet volume normalized by the adiabatic value, for the selected regions, shows the same dispersion as the distribution of normalized concentration. The values of droplet concentration versus mean volume diameter are then examined in sub-adiabatic samples to characterize the effects of mixing and drizzle scavenging. Finally, the ratio of mean volume diameter to effective diameter is analyzed and a simple relationship between these 2 crucial parameters is proposed.","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":"50 1","pages":"868-887"},"PeriodicalIF":2.3,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81689164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-04-01DOI: 10.1034/J.1600-0889.2000.00047.X
J. Brenguier, P. Chuang, Y. Fouquart, Douglas W. Johnson, F. Parol, H. Pawłowska, J. Pelon, L. Schüller, F. Schroder, J. Snider
CLOUDYCOLUMN is one of the 6 ACE-2 projects which took place in June-July 1997, between Portugal and the Canary Islands. It was specifically dedicated to the study of changes of cloud radiative properties resulting from changes in the properties of those aerosols which act as cloud condensation nuclei. This process is also refered to as the aerosol indirect effect on climate. CLOUDYCOLUMN is focused on the contribution of stratocumulus clouds to that process. In addition to the basic aerosol measurements performed at the ground stations of the ACE-2 project, 5 instrumented aircraft carried out in situ characterization of aerosol physical, chemical and nucleation properties and cloud dynamical and microphysical properties. Cloud radiative properties were also measured remotely with radiometers and a lidar. 11 case studies have been documented, from pure marine to significantly polluted air masses. The simultaneity of the measurements with the multi-aircraft approach provides a unique data set for closure experiments on the aerosol indirect effect. In particular CLOUDYCOLUMN provided the 1st experimental evidence of the existence of the indirect effect in boundary layer clouds forming in polluted continental outbreacks. This paper describes the objectives of the project, the instrumental setup and the sampling strategy. Preliminary results published in additional papers are briefly summarized.
{"title":"An overview of the ACE2 CLOUDYCOLUMN closure experiment","authors":"J. Brenguier, P. Chuang, Y. Fouquart, Douglas W. Johnson, F. Parol, H. Pawłowska, J. Pelon, L. Schüller, F. Schroder, J. Snider","doi":"10.1034/J.1600-0889.2000.00047.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.00047.X","url":null,"abstract":"CLOUDYCOLUMN is one of the 6 ACE-2 projects which took place in June-July 1997, between Portugal and the Canary Islands. It was specifically dedicated to the study of changes of cloud radiative properties resulting from changes in the properties of those aerosols which act as cloud condensation nuclei. This process is also refered to as the aerosol indirect effect on climate. CLOUDYCOLUMN is focused on the contribution of stratocumulus clouds to that process. In addition to the basic aerosol measurements performed at the ground stations of the ACE-2 project, 5 instrumented aircraft carried out in situ characterization of aerosol physical, chemical and nucleation properties and cloud dynamical and microphysical properties. Cloud radiative properties were also measured remotely with radiometers and a lidar. 11 case studies have been documented, from pure marine to significantly polluted air masses. The simultaneity of the measurements with the multi-aircraft approach provides a unique data set for closure experiments on the aerosol indirect effect. In particular CLOUDYCOLUMN provided the 1st experimental evidence of the existence of the indirect effect in boundary layer clouds forming in polluted continental outbreacks. This paper describes the objectives of the project, the instrumental setup and the sampling strategy. Preliminary results published in additional papers are briefly summarized.","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":"17 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87338847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-04-01DOI: 10.1034/J.1600-0889.2000.00027.X
K. Bower, T. Choularton, M. Gallagher, K. Beswick, M. Flynn, A. G. Allen, B. Davison, J. James, L. Robertson, R. Harrison, C. Hewitt, J. Cape, G. G. McFadyen, C. Milford, M. Sutton, B. Martinsson, G. Frank, E. Swietlicki, Jingchuan Zhou, Olle H. Berg, B. Mentes, G. Papaspiropoulos, H. Hansson, C. Leck, M. Kulmala, P. Aalto, M. Väkevä, A. Berner, M. Bizjak, S. Fuzzi, P. Laj, M. Facchini, G. Orsi, Loretta Ricci, M. Nielsen, B. Allan, H. Coe, G. Mcfiggans, J. Plane, J. Collett, K. Moore, D. Sherman
The ACE‐2 HILLCLOUD experiment was carried out on the island of Tenerife in June–July 1997 to investigate the interaction of the boundary layer aerosol with a hill cap cloud forming over a ridge to the north‐east of the island. The cloud was used as a natural flow through reactor to investigate the dependence of the cloud microphysics and chemistry on the characteristics of the aerosols and trace gases entering cloud, and to simultaneously study the influence of the physical and chemical processes occurring within the cloud on the size distribution, chemical and hygroscopic properties of the aerosol exiting cloud. 5 major ground base sites were used, measuring trace gases and aerosols upwind and downwind of the cloud, and cloud microphysics and chemistry and interstitial aerosol and gases within the cloud on the hill. 8 intensive measurement periods or runs were undertaken during cloud events, (nocturnally for seven of the eight runs) and were carried out in a wide range of airmass conditions from clean maritime to polluted continental. Polluted air was characterised by higher than average concentrations of ozone (>50 ppbv), fine and accumulation mode aerosols (>3000 and >1500 cm−3, respectively) and higher aerosol mass loadings. Cloud droplet number concentrations N, increased from 50 cm−3 in background maritime air to >2500 cm−3 in aged polluted continental air, a concentration much higher than had previously been detected. Surprisingly, N was seen to vary almost linearly with aerosol number across this range. The droplet aerosol analyser (DAA) measured higher droplet numbers than the corrected forward scattering spectrometer probe (FSSP) in the most polluted air, but at other times there was good agreement (FSSP=0.95 DAA with an r2=0.89 for N<1200 cm−3). Background ammonia gas concentrations were around 0.3 ppbv even in air originating over the ocean, another unexpected but important result for the region. NO2 was present in background concentrations of typically 15 pptv to 100 pptv and NO˙3 (the nitrate radical) was observed at night throughout. Calculations suggest NO˙3 losses were mainly by reaction with DMS to produce nitric acid. Low concentrations of SO2(∼30 pptv), HNO3 and HCl were always present. HNO3 concentrations were higher in polluted episodes and calculations implied that these exceeded those which could be accounted for by NO2 oxidation. It is presumed that nitric and hydrochloric acids were present as a result of outgassing from aerosol, the HNO3 from nitrate rich aerosol transported into the region from upwind of Tenerife, and HCl from sea salt aerosol newly formed at the sea surface. The oxidants hydrogen peroxide and ozone were abundant (i.e., were well in excess over SO2 throughout the experiment). Occasions of significant aerosol growth following cloud processing were observed, particularly in cleaner cases. Observations and modelling suggested this was due mainly to the take up of nitric acid, hydrochloric acid and ammoni
{"title":"ACE-2 HILLCLOUD. An overview of the ACE-2 ground-based cloud experiment","authors":"K. Bower, T. Choularton, M. Gallagher, K. Beswick, M. Flynn, A. G. Allen, B. Davison, J. James, L. Robertson, R. Harrison, C. Hewitt, J. Cape, G. G. McFadyen, C. Milford, M. Sutton, B. Martinsson, G. Frank, E. Swietlicki, Jingchuan Zhou, Olle H. Berg, B. Mentes, G. Papaspiropoulos, H. Hansson, C. Leck, M. Kulmala, P. Aalto, M. Väkevä, A. Berner, M. Bizjak, S. Fuzzi, P. Laj, M. Facchini, G. Orsi, Loretta Ricci, M. Nielsen, B. Allan, H. Coe, G. Mcfiggans, J. Plane, J. Collett, K. Moore, D. Sherman","doi":"10.1034/J.1600-0889.2000.00027.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.00027.X","url":null,"abstract":"The ACE‐2 HILLCLOUD experiment was carried out on the island of Tenerife in June–July 1997 to investigate the interaction of the boundary layer aerosol with a hill cap cloud forming over a ridge to the north‐east of the island. The cloud was used as a natural flow through reactor to investigate the dependence of the cloud microphysics and chemistry on the characteristics of the aerosols and trace gases entering cloud, and to simultaneously study the influence of the physical and chemical processes occurring within the cloud on the size distribution, chemical and hygroscopic properties of the aerosol exiting cloud. 5 major ground base sites were used, measuring trace gases and aerosols upwind and downwind of the cloud, and cloud microphysics and chemistry and interstitial aerosol and gases within the cloud on the hill. 8 intensive measurement periods or runs were undertaken during cloud events, (nocturnally for seven of the eight runs) and were carried out in a wide range of airmass conditions from clean maritime to polluted continental. Polluted air was characterised by higher than average concentrations of ozone (>50 ppbv), fine and accumulation mode aerosols (>3000 and >1500 cm−3, respectively) and higher aerosol mass loadings. Cloud droplet number concentrations N, increased from 50 cm−3 in background maritime air to >2500 cm−3 in aged polluted continental air, a concentration much higher than had previously been detected. Surprisingly, N was seen to vary almost linearly with aerosol number across this range. The droplet aerosol analyser (DAA) measured higher droplet numbers than the corrected forward scattering spectrometer probe (FSSP) in the most polluted air, but at other times there was good agreement (FSSP=0.95 DAA with an r2=0.89 for N<1200 cm−3). Background ammonia gas concentrations were around 0.3 ppbv even in air originating over the ocean, another unexpected but important result for the region. NO2 was present in background concentrations of typically 15 pptv to 100 pptv and NO˙3 (the nitrate radical) was observed at night throughout. Calculations suggest NO˙3 losses were mainly by reaction with DMS to produce nitric acid. Low concentrations of SO2(∼30 pptv), HNO3 and HCl were always present. HNO3 concentrations were higher in polluted episodes and calculations implied that these exceeded those which could be accounted for by NO2 oxidation. It is presumed that nitric and hydrochloric acids were present as a result of outgassing from aerosol, the HNO3 from nitrate rich aerosol transported into the region from upwind of Tenerife, and HCl from sea salt aerosol newly formed at the sea surface. The oxidants hydrogen peroxide and ozone were abundant (i.e., were well in excess over SO2 throughout the experiment). Occasions of significant aerosol growth following cloud processing were observed, particularly in cleaner cases. Observations and modelling suggested this was due mainly to the take up of nitric acid, hydrochloric acid and ammoni","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":"7 1","pages":"750-778"},"PeriodicalIF":2.3,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78527324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-04-01DOI: 10.1034/J.1600-0889.2000.00006.X
P. Formenti, M. Andreae, J. Lelieveld
As part of the 2nd Aerosol Characterisation Experiment (ACE-2), conducted during summer 1997 in the North Atlantic region between the Canary Islands and Portugal, we measured aerosol optical depths (AOD) at a mid-tropospheric site, near the top of the volcanic mountain “El Teide”(28°16′N, 16°36′ W, 3570 m asl). Our instrument was located at the highest altitude in a network of sunphotometers that extended down to sea level. Clear conditions dominated the ACE-2 period, and, although suggested by back-trajectories at 300 hPa, no evidence of anthropogenic pollution was found in our data. Three distinct dust episodes were observed. Vertical soundings and back trajectories suggested mineral dust from the Sahel region as a source. During these episodes, AOD increased an order of magnitude with respect to background conditions (from 0.017 up to 0.19 at λ=500 nm). A shift towards neutrality of the extinction spectral dependence (Angstrom exponent α down to 0.13), indicated that the coarse mode (particle diameter >2 μm) dominated the aerosol size distribution. For 6 days during the episodes of mineral dust, a monomodal size distribution between 2 and 20 μm diameter was obtained from Mie based size distribution calculations. Estimates, at 500 nm, of the single scattering albedo ω0(0.87–0.96), and the aerosol asymmetry parameter g(0.72–0.73) suggest that the dust layer causes a net cooling forcing at the top of the atmosphere.
{"title":"Measurements of aerosol optical depth above 3570 m asl in the North Atlantic free troposphere: results from ACE‐2","authors":"P. Formenti, M. Andreae, J. Lelieveld","doi":"10.1034/J.1600-0889.2000.00006.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.00006.X","url":null,"abstract":"As part of the 2nd Aerosol Characterisation Experiment (ACE-2), conducted during summer 1997 in the North Atlantic region between the Canary Islands and Portugal, we measured aerosol optical depths (AOD) at a mid-tropospheric site, near the top of the volcanic mountain “El Teide”(28°16′N, 16°36′ W, 3570 m asl). Our instrument was located at the highest altitude in a network of sunphotometers that extended down to sea level. Clear conditions dominated the ACE-2 period, and, although suggested by back-trajectories at 300 hPa, no evidence of anthropogenic pollution was found in our data. Three distinct dust episodes were observed. Vertical soundings and back trajectories suggested mineral dust from the Sahel region as a source. During these episodes, AOD increased an order of magnitude with respect to background conditions (from 0.017 up to 0.19 at λ=500 nm). A shift towards neutrality of the extinction spectral dependence (Angstrom exponent α down to 0.13), indicated that the coarse mode (particle diameter >2 μm) dominated the aerosol size distribution. For 6 days during the episodes of mineral dust, a monomodal size distribution between 2 and 20 μm diameter was obtained from Mie based size distribution calculations. Estimates, at 500 nm, of the single scattering albedo ω0(0.87–0.96), and the aerosol asymmetry parameter g(0.72–0.73) suggest that the dust layer causes a net cooling forcing at the top of the atmosphere.","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":"211 1","pages":"678-693"},"PeriodicalIF":2.3,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77053982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-04-01DOI: 10.1034/J.1600-0889.2000.00028.X
V. Vitale, C. Tomasi, W. V. Hoyningen-Huene, U. Bonafè, S. Marani, A. Lupi, A. Cacciari, P. Ruggeri
During the CLEARCOLUMN campaign which took place at Sagres (Portugal) from 16 June to 25 July 1997, more than 2000 spectral measurements of direct solar irradiance were performed at thirteen window-wavelengths in the 0.4–3.7 μm range, on 27 days. The measurements were performed using the IR-RAD sun-radiometer designed and manufactured at the Institute ISAO (FISBAT), Bologna (Italy), and carefully calibrated by applying the Langley plot method to the measurements performed on 24 October 1996, at the Schneefernerhaus Observatory on the Zugspitze (Germany). From these measurements, the values of the total atmospheric optical depth were obtained at the various wavelengths, from which the corresponding spectral values of aerosol optical depth were determined through accurate corrections for Rayleigh scattering and gaseous absorption. Such values were found to be mostly smaller than 0.1 during June and early July, presenting almost neutral spectral dependence characteristics, closely related to the prevailing oceanic origins of particulate matter. Higher values of aerosol optical thickness, mainly ranging between 0.1 and 0.5 at visible wavelengths and sharply decreasing with wavelength, were found during the rest of July in the presence of predominant contents of continental and anthropogenic aerosol particles arriving from polluted European regions. The King inversion method was applied to the spectral series of aerosol optical depth to determine the particle size-distribution curves in the 0.2–20 μm diameter range. For 2 of these cases (one chosen for a low atmospheric loading of marine aerosols and the other for a mean content of continental/anthropogenic aerosols), the changes in the outgoing solar radiation flux produced by aerosol particles were calculated, considering different surface albedo conditions. The results obtained in the second case show that changes of opposite sign can be caused by the same atmospheric aerosol loading when passing from oceanic to continental areas.
{"title":"Spectral measurements of aerosol particle extinction in the 0.4–3.7 μm wavelength range, performed at Sagres with the IR‐RAD sun‐radiometer","authors":"V. Vitale, C. Tomasi, W. V. Hoyningen-Huene, U. Bonafè, S. Marani, A. Lupi, A. Cacciari, P. Ruggeri","doi":"10.1034/J.1600-0889.2000.00028.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.00028.X","url":null,"abstract":"During the CLEARCOLUMN campaign which took place at Sagres (Portugal) from 16 June to 25 July 1997, more than 2000 spectral measurements of direct solar irradiance were performed at thirteen window-wavelengths in the 0.4–3.7 μm range, on 27 days. The measurements were performed using the IR-RAD sun-radiometer designed and manufactured at the Institute ISAO (FISBAT), Bologna (Italy), and carefully calibrated by applying the Langley plot method to the measurements performed on 24 October 1996, at the Schneefernerhaus Observatory on the Zugspitze (Germany). From these measurements, the values of the total atmospheric optical depth were obtained at the various wavelengths, from which the corresponding spectral values of aerosol optical depth were determined through accurate corrections for Rayleigh scattering and gaseous absorption. Such values were found to be mostly smaller than 0.1 during June and early July, presenting almost neutral spectral dependence characteristics, closely related to the prevailing oceanic origins of particulate matter. Higher values of aerosol optical thickness, mainly ranging between 0.1 and 0.5 at visible wavelengths and sharply decreasing with wavelength, were found during the rest of July in the presence of predominant contents of continental and anthropogenic aerosol particles arriving from polluted European regions. The King inversion method was applied to the spectral series of aerosol optical depth to determine the particle size-distribution curves in the 0.2–20 μm diameter range. For 2 of these cases (one chosen for a low atmospheric loading of marine aerosols and the other for a mean content of continental/anthropogenic aerosols), the changes in the outgoing solar radiation flux produced by aerosol particles were calculated, considering different surface albedo conditions. The results obtained in the second case show that changes of opposite sign can be caused by the same atmospheric aerosol loading when passing from oceanic to continental areas.","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":"36 1","pages":"716-733"},"PeriodicalIF":2.3,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83126802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-04-01DOI: 10.1034/J.1600-0889.2000.00032.X
C. Tomasi, S. Marani, V. Vitale, F. Wagner, A. Cacciari, A. Lupi
Measurements of direct solar irradiance were taken employing 4 different sun-photometers at near infrared wavelengths, suitable for use in atmospheric hygrometry. This technique utilising a set of spectral ratios, in and out of selected water vapour absorption bands, was applied to the measurements to obtain accurate evaluations of precipitable water. For all the hygrometric ratios given by the 4 sun-photometers used at the 3 stations of Sagres, Monchique and Mt. Foia, during the CLEARCOLUMN experiment, we determined the calibration curves by correcting them for the Rayleigh scattering effects and, then, plotting the natural logarithms of such corrected ratios versus the square root of the water vapour mass present along the atmospheric slant path. The regression lines drawn for the various scatter diagrams were estimated to give evaluations of precipitable water with an uncertainty of less than 5%, 3% and 10% at the 3 stations, respectively. The calibration curves of the sun-photometer located at the Sagres station were determined using the precipitable water evaluations obtained from the local radiosounding measurements taken on 5 clear-sky days. Those of the sun-photometers used at the Monchique and Mt. Foia stations were instead determined through intercomparison between subsets of measurements simultaneously taken with various instruments at Sagres and Mt. Foia. Using these calibration curves, we examined all the field measurements determining the time-patterns of precipitable water at the 3 stations. During the period from 16 June to 25 July 1997, precipitable water was found to vary between 1.1 and 3.7 g cm−2 at the Sagres station (with an accuracy within ±13%), between 1.0 and 2.8 g cm−2 at Monchique (±11%) and between 0.8 and 3.0 g cm−2 at the top of Mt. Foia (±26%).
使用四种不同的近红外波长太阳光度计测量太阳直接辐照度，适合用于大气湿度测量。这项技术利用一组光谱比，在选定的水蒸气吸收带内和外，应用于测量，以获得可降水量的准确评估。在CLEARCOLUMN实验期间，我们对Sagres、Monchique和Foia山3个站点使用的4台太阳光度计给出的所有湿度计比，通过校正瑞利散射效应来确定校准曲线，然后绘制校正后的比率与沿大气倾斜路径存在的水蒸气质量的平方根的自然对数。估计各散点图的回归线对3个站点的可降水量的不确定度分别小于5%、3%和10%。位于Sagres站的太阳光度计的校正曲线是根据当地5个晴天的无线电测深测量所得的可降水量值来确定的。Monchique站和Foia山站使用的太阳光度计的测量值是通过在Sagres和Foia山用各种仪器同时测量的子集之间的相互比较确定的。利用这些校准曲线，我们检查了所有野外测量结果，确定了3个站点的可降水量的时间模式。1997年6月16日至7月25日期间，Sagres站的可降水量在1.1 - 3.7 g cm - 2之间变化(精度在±13%以内)，Monchique站的可降水量在1.0 - 2.8 g cm - 2之间变化(±11%)，Foia山顶的可降水量在0.8 - 3.0 g cm - 2之间变化(±26%)。
{"title":"Precipitable water evaluations from infrared sun‐photometric measurements analyzed using the atmospheric hygrometry technique","authors":"C. Tomasi, S. Marani, V. Vitale, F. Wagner, A. Cacciari, A. Lupi","doi":"10.1034/J.1600-0889.2000.00032.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.00032.X","url":null,"abstract":"Measurements of direct solar irradiance were taken employing 4 different sun-photometers at near infrared wavelengths, suitable for use in atmospheric hygrometry. This technique utilising a set of spectral ratios, in and out of selected water vapour absorption bands, was applied to the measurements to obtain accurate evaluations of precipitable water. For all the hygrometric ratios given by the 4 sun-photometers used at the 3 stations of Sagres, Monchique and Mt. Foia, during the CLEARCOLUMN experiment, we determined the calibration curves by correcting them for the Rayleigh scattering effects and, then, plotting the natural logarithms of such corrected ratios versus the square root of the water vapour mass present along the atmospheric slant path. The regression lines drawn for the various scatter diagrams were estimated to give evaluations of precipitable water with an uncertainty of less than 5%, 3% and 10% at the 3 stations, respectively. The calibration curves of the sun-photometer located at the Sagres station were determined using the precipitable water evaluations obtained from the local radiosounding measurements taken on 5 clear-sky days. Those of the sun-photometers used at the Monchique and Mt. Foia stations were instead determined through intercomparison between subsets of measurements simultaneously taken with various instruments at Sagres and Mt. Foia. Using these calibration curves, we examined all the field measurements determining the time-patterns of precipitable water at the 3 stations. During the period from 16 June to 25 July 1997, precipitable water was found to vary between 1.1 and 3.7 g cm−2 at the Sagres station (with an accuracy within ±13%), between 1.0 and 2.8 g cm−2 at Monchique (±11%) and between 0.8 and 3.0 g cm−2 at the top of Mt. Foia (±26%).","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":"20 1","pages":"734-749"},"PeriodicalIF":2.3,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80893073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-04-01DOI: 10.1034/J.1600-0889.2000.00049.X
C. Carrico, M. Rood, J. Ogren, C. Neusüß, A. Wiedensohler, J. Heintzenberg
Aerosol light scattering and absorption properties relevant to climate change were measured as part of the Aerosol Characterization Experiment 2 (ACE-2, 15 June to 25 July 1997) at Sagres, Portugal, a site receiving anthropogenically perturbed air masses from Europe. A controlled relative humidity (RH) nephelometry system measured the dependence of the total light scattering and backscattering coefficients by particles (σsp and σbsp , respectively) upon increasing and decreasing controlled RH, maximum particle diameter (Dp) size cut, and wavelength of scattered light (λ). An aethalometer was used to measure black carbon concentrations ([BC]) to yield estimates of light absorption by particles (σap) and single scattering albedo (ω). Parameters derived from the measurements include the dependence of σsp and σbsp on RH (f(RH)), the hemispheric backscatter fraction (b), and the Angstrom exponent (A), all as functions of λ and particle Dp size cut. During polluted periods, for Dp≤10 μm, and at λ=550 nm, means and standard deviations of aerosol parameters included σsp=75.1±30.5 Mm−1 at controlled RH=27%, f(RH=82%)=1.46±0.10 and 1.22±0.06 for σsp and σbsp , respectively, and b=0.113±0.017 and 0.094±0.015 at controlled RH=27% and 82%, respectively. Transition from “clean” to polluted periods was characterized by a mean increase in σsp and σbsp by a factor of 4 to 7, increased wavelength dependence evident from an increase in A from 0.57 to 1.48, shift from 0.32 to 0.56 of the fraction of σsp from sub-micrometer Dp particles, and suppression of f(RH) by 14 to 20%. Onset of polluted periods and aerosol hygroscopic growth each resulted in ∼1% increases in ω, and an estimated range for ω at Sagres during ACE-2 was 0.91<ω< 0.97 considering uncertainty of ±0.02, aerosol hygroscopic growth, and air mass influences. Evidence for the influence of hysteresis in f(RH) was greatest at RH=65% with mean increases of 20% during “clean” periods and 10% during polluted periods. These measurements contribute to characterizing ground-level aerosol optical properties for a site that receives “clean” and anthropogenically perturbed aerosol.
{"title":"Aerosol Optical properties at Sagres, Portugal during ACE‐2","authors":"C. Carrico, M. Rood, J. Ogren, C. Neusüß, A. Wiedensohler, J. Heintzenberg","doi":"10.1034/J.1600-0889.2000.00049.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.00049.X","url":null,"abstract":"Aerosol light scattering and absorption properties relevant to climate change were measured as part of the Aerosol Characterization Experiment 2 (ACE-2, 15 June to 25 July 1997) at Sagres, Portugal, a site receiving anthropogenically perturbed air masses from Europe. A controlled relative humidity (RH) nephelometry system measured the dependence of the total light scattering and backscattering coefficients by particles (σsp and σbsp , respectively) upon increasing and decreasing controlled RH, maximum particle diameter (Dp) size cut, and wavelength of scattered light (λ). An aethalometer was used to measure black carbon concentrations ([BC]) to yield estimates of light absorption by particles (σap) and single scattering albedo (ω). Parameters derived from the measurements include the dependence of σsp and σbsp on RH (f(RH)), the hemispheric backscatter fraction (b), and the Angstrom exponent (A), all as functions of λ and particle Dp size cut. During polluted periods, for Dp≤10 μm, and at λ=550 nm, means and standard deviations of aerosol parameters included σsp=75.1±30.5 Mm−1 at controlled RH=27%, f(RH=82%)=1.46±0.10 and 1.22±0.06 for σsp and σbsp , respectively, and b=0.113±0.017 and 0.094±0.015 at controlled RH=27% and 82%, respectively. Transition from “clean” to polluted periods was characterized by a mean increase in σsp and σbsp by a factor of 4 to 7, increased wavelength dependence evident from an increase in A from 0.57 to 1.48, shift from 0.32 to 0.56 of the fraction of σsp from sub-micrometer Dp particles, and suppression of f(RH) by 14 to 20%. Onset of polluted periods and aerosol hygroscopic growth each resulted in ∼1% increases in ω, and an estimated range for ω at Sagres during ACE-2 was 0.91<ω< 0.97 considering uncertainty of ±0.02, aerosol hygroscopic growth, and air mass influences. Evidence for the influence of hysteresis in f(RH) was greatest at RH=65% with mean increases of 20% during “clean” periods and 10% during polluted periods. These measurements contribute to characterizing ground-level aerosol optical properties for a site that receives “clean” and anthropogenically perturbed aerosol.","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":"7 1","pages":"694-715"},"PeriodicalIF":2.3,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83983047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：