Tellus Series B-Chemical and Physical Meteorology最新文献

{"title":"Modelling cloud processing of aerosol during the ACE-2 HILLCLOUD experiment","authors":"M. Flynn, K. Bower, T. Choularton, W. Wobrock, J. Mäkelä, B. Martinsson, G. Frank, H. Hansson, Hans Karlsson, P. Laj","doi":"10.1034/J.1600-0889.2000.00029.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.00029.X","url":null,"abstract":"A numerical model has been used to simulate the conditions observed during the ACE-2 Hillcloud experiment and to study the processes which may be taking place. The model incorporates gas phase chemistry of sulphur and nitrogen compounds upstream of the cloud, and the interaction of aerosol, precursor trace gases and oxidants within the cloud. Gas phase and aerosol inputs to the model have been provided from measurements made in the field. Dynamics of the air flow over the hill consisted of simple prescribed dynamics based on wind speed measurements, and also for some cases modelled dynamics. In this modelling study, it was found that during clean case studies particles down to 40-55 nm diameter were activated to form cloud droplets, the total number of droplets formed ranging from 200 to 400 drops/cm(3) Significant modification of the aerosol spectra due to cloud processing was observed. In polluted cases particles down to 65-80 nm diameter were activated to form cloud droplets, the total number of droplets ranging from 800 to 2800 drops/cm(3). Modification of the aerosol spectra due to cloud processing was slight. In all cases, changes in the aerosol spectra were due to both the uptake of HNO3, HCl, NH3 and SO2 from the gas phase, (the SO2 being oxidised to sulphate) and the repartitioning of species such as HNO3, HCl, and NH3 from larger particles onto smaller ones. Modelling results have been compared with observations made. Modelled droplet numbers are typically within 20% of the best measured values. The mode of the droplet distribution typically around 10 20 mu m for clean cases and 4-8 mu m for polluted cases was found to be in good agreement with the measured values of 10-25 mu m for clean cases, but not in such good agreement for polluted cases. Measurements of upwind and interstitial aerosol distributions showed that the smallest particles activated were 30 and 50 nm for clean and polluted cases respectively, slightly smaller than the model values quoted above. Measured upwind and downwind aerosol spectra showed similar modification to that predicted by the model in eight out of the eleven model runs carried out. Chemistry measurements also give general evidence for both the uptake of species from the gas phase, and repartitioning of species from large particles onto smaller ones, though comparisons For individual cases are more difficult. From this modelling study, it can be concluded that in general, in the remote environment the exchange of hydrochloric acid, nitric acid and ammonia between aerosol particles and take up from the gas phase in the vicinity of cloud may be a very important mechanism in regulating the evolution of the aerosol spectrum. Further, the much more linear relationship between cloud droplet and accumulation mode aerosol number, which was observed in the measurements made during the ACE-2 HILLCLOUD project is supported by these modelling results. The implications of this for the indirect effect will be explored i","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85809624","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}

{"title":"Cloud optical thickness and albedo retrievals from bidirectional reflectance measurements of POLDER instruments during ACE‐2","authors":"F. Parol, J. Descloitres, Y. Fouquart","doi":"10.1034/J.1600-0889.2000.00026.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.00026.X","url":null,"abstract":"The POLDER instrument is devoted to global observations of the solar radiation reflected by the Earth–atmosphere system. The airborne version of the instrument was operated during the ACE-2 experiment, more particularly as a component of the CLOUDYCOLUMN project of ACE-2 that was conducted in summer 1997 over the subtropical northeastern Atlantic ocean. CLOUDYCOLUMN is a coordinated project specifically dedicated to the study of the indirect effect of aerosols. In this context, the airborne POLDER was assigned to remote measurements of the cloud optical and radiative properties, namely the cloud optical thickness and the cloud albedo. This paper presents the retrievals of those 2 cloud parameters for 2 golden days of the campaign 26 June and 9 July 1997. Coincident spaceborne ADEOS-POLDER data from 2 orbits over the ACE-2 area on 26 June are also analyzed. 26 June corresponds to a pure air marine case and 9 July is a polluted air case. The multidirectional viewing capability of airborne POLDER is here demonstrated to be very useful to estimate the effective radius of cloud droplet that characterizes the observed stratocumulus clouds. A 12 μm cloud droplet size distribution appears to be a suitable cloud droplet model in the pure marine cloud case study. For the polluted case the mean retrieved effective droplet radius is of the order of 6–10 μm. This only preliminary result can be interpreted as a confirmation of the indirect effect of aerosols. It is consistent with the significant increase in droplet concentration measured in polluted marine clouds compared to clean marine ones. Further investigations and comparisons to in-situ microphysical measurements are now needed.","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82583478","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}

{"title":"Cloud condensation nuclei and cloud droplet measurements during ACE-2","authors":"J. Snider, J. Brenguier","doi":"10.1034/J.1600-0889.2000.00044.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.00044.X","url":null,"abstract":"During the 2nd Aerosol Characterization Experiment (ACE-2), relationships between stratocumulus cloud properties and aerosols were examined. Here, the relevant measurements including the cloud condensation nuclei (CCN) activation spectrum, updraft velocity, cloud microphysical and aerosol properties are presented. It is shown that calculations of droplet concentration based on updraft velocity and the CCN activation spectrum are consistent with direct observations. Also discussed is an apparent disparity among measurements of the CCN activation spectrum, the accumulation mode size distribution, and the composition of the submicrometric aerosol. The observed consistency between CCN, updraft and cloud droplets is a necessary refinement; however, extended analyses of the ACE-2 data set are needed to guide improvements in model simulations of the interaction between aerosols and cloud microphysics. In particular, there is need for an examination of aerosol size spectra and chemical composition measurements with a view towards validating droplet activation schemes which relate the aerosol and cloud dynamical properties to cloud albedo.","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86437118","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}

{"title":"Validation of very high cloud droplet number concentrations in air masses transported thousands of kilometres over the ocean","authors":"B. Martinsson, G. Frank, S. Cederfelt, Olle H. Berg, B. Mentes, G. Papaspiropoulos, E. Swietlicki, Jingchuan Zhou, M. Flynn, K. Bower, T. Choularton, J. Mäkelä, A. Virkkula, R. Dingenen","doi":"10.1034/J.1600-0889.2000.00020.X","DOIUrl":"https://doi.org/10.1034/J.1600-0889.2000.00020.X","url":null,"abstract":"The microstructure of orographic clouds related to the aerosol present was studied during the second Aerosol Characterisation Experiment (ACE-2). Very high cloud droplet number concentrations (almost 3000 cm(-3)) were observed. These high concentrations occurred when clouds formed on a hill slope at Tenerife in polluted air masses originating in Europe that had transported the order of 1000 km over the Atlantic Ocean. The validity of the measured droplet number concentrations was investigated by comparing with measurements of the aerosol upstream of the cloud and cloud interstitial aerosol. Guided by distributions of the ratios between the measurements, three criteria of typically 30% in maximum deviation were applied to the measurements to test their validity. Agreement was found for 88% of the cases. The validated data set spans droplet number concentrations of 150 3000 cm(-3). The updraught velocity during the cloud formation was estimated to 2.2 m s(-1) by model calculations, which is typical of cumuliform clouds. The results of the present study are discussed in relation to cloud droplet number concentrations previously reported in the literature. The importance of promoting the mechanistic understanding of the aerosol/cloud interaction and the use of validation procedures of cloud microphysical parameters is stressed in relation to the assessment of the indirect climatic effect of aerosols.","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82690897","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}

{"title":"Terrestrial carbon sink in the Northern Hemisphere estimated from the atmospheric CO2 difference between Mauna Loa and the South Pole since 1959","authors":"S. Fan, T. Blaine, J. Sarmiento","doi":"10.3402/TELLUSB.V51I5.16499","DOIUrl":"https://doi.org/10.3402/TELLUSB.V51I5.16499","url":null,"abstract":"The diVerence between Mauna Loa and South Pole atmospheric CO 2 concentrations from 1959 to the present scales linearly with CO 2 emissions from fossil fuel burning and cement production (together called fossil CO 2 ). An extrapolation to zero fossil CO 2 emission has been used to suggest that the atmospheric CO 2 concentration at Mauna Loa was 0.8 ppm less than that at the South Pole before the industrial revolution, associated with a northward atmospheric transport of about 1 Gt C yr −1 (Keeling et al. 1989a). Mass conservation requires an equal southward transport in the ocean. However, our ocean general circulation and biogeochemistry model predicts a much smaller pre-industrial carbon transport. Here, we present a new analysis of the Mauna Loa and South Pole CO 2 data, using a general circulation model and a 2-box model of the atmosphere. It is suggested that the present CO 2 diVerence between Mauna Loa and the South Pole is caused by, in addition to fossil CO 2 sources and sinks, a pre-industrial interhemispheric flux of 0.5–0.7 Gt C yr −1 , and a terrestrial sink of 0.8–1.2 Gt C yr −1 in the mid-latitude Northern Hemisphere, balanced by a tropical deforestation source that has been operating continuously in the period from 1959 to the present. DOI: 10.1034/j.1600-0889.1999.t01-4-00001.x","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83504348","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}

{"title":"CO emissions from degrading plant matter (II).: Estimate of a global source strength","authors":"G. Schade, P. Crutzen","doi":"10.3402/TELLUSB.V51I5.16503","DOIUrl":"https://doi.org/10.3402/TELLUSB.V51I5.16503","url":null,"abstract":"From relationships between integrated daily CO emissions and received solar radiation obtained for different standing dead grasses in field experiments in a savanna region in South Africa, and making use of ecosystem and solar irradiation databases, we derive estimates on global CO production and seasonality from photochemical decay of dry grasses and litter. The photochemical CO source strength from standing dead plant material and litter in various grassland ecosystems and deciduous forests ranges from 20 to 65 Tg CO per year (1 Tg = 10 12 g). Accounting for potentially CO emitting ecosystems not included in the data set, we estimate that 60 ± 30 Tg of CO are annually emitted by photochemical degradation of decaying plant matter, mostly in the tropics. We further estimate thermal CO production from the global topsoil non-woody litter pool on the basis of global climate data and measured Arrhenius parameters to add another 40 Tg CO per year, much depending on the chosen parameters, and probably uncertain by a factor of 2. The total global source of CO by these mechanisms may thus be in the range 100 +70 −50 Tg CO per year. Although the estimated CO source strength is a relatively small contribution to the global CO budget (2–8%), CO emissions may significantly compensate for CO deposition on soils in the tropics during certain times of the year. Currently, modelling studies mostly impose a constant CO deposition velocity from the atmosphere to the soil surface, based generally on measurements on bare soil. Future modelling efforts may need to include geographical and photochemical factors which play a role in CO exchange in tropical ecosystems. DOI: 10.1034/j.1600-0889.1999.t01-4-00004.x","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91378971","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}

{"title":"CO emissions from degrading plant matter.","authors":"G. Schade, Rolf Hofmann, P. Crutzen","doi":"10.3402/TELLUSB.V51I5.16501","DOIUrl":"https://doi.org/10.3402/TELLUSB.V51I5.16501","url":null,"abstract":"CO emissions from degrading deciduous leaf and grass matter have been investigated in laboratory and field measurements. CO emissions are induced both photochemically and thermally. Photochemical CO production can be described by a 2nd-order polynomial in light intensity and exhibits a hysteresis effect, not previously reported. Humid material showed higher CO emissions than dry material. A preliminary, relative action spectrum for the photochemically induced CO emissions is presented. Although UV irradiation caused most of the CO production, visible light also caused up to 40% of the emissions. We propose a cleavage of the cellulose chain as the important step prior to CO production. Thermal CO emissions from degrading plant material obey an Arrhenius type equation (presented for several species in this paper), but emissions are lower than those induced photochemically. During our field measurements on dry grasses in a South African savanna we found a strong influence of incident radiation intensity and temperature on measured CO fluxes. Solely photochemical CO production from the grasses is calculated by subtraction of soil fluxes and thermally induced grass CO emissions from the total CO emissions. CO emissions and hysteresis differ between the grasses investigated and may be interpreted by the grass' colour and their architecture. Deposition of CO on the soils was much lower than CO emission from the dry grasses during daytime. Nighttime data show that possible thermal CO production from the grasses may partially compensate for CO deposition on the soils for several hours after sunset depending on temperature. DOI: 10.1034/j.1600-0889.1999.t01-4-00003.x","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90165303","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}

{"title":"Modelling the production and cycling of dimethylsulphide during the vernal bloom in the Barents Sea","authors":"A. Gabric, P. Matrai, M. Vernet","doi":"10.3402/TELLUSB.V51I5.16505","DOIUrl":"https://doi.org/10.3402/TELLUSB.V51I5.16505","url":null,"abstract":"Recent field work suggests an important ro^le for the Arctic Ocean in the global budget of dimethylsulphide (DMS), a climatically active volatile sulphur compound. Here, we have used an existing DMS production model and local field data to examine the temporal dynamics of the DMS cycle during the spring bloom in the Arctic shelf of the Barents Sea. The timing and duration of the spring phytoplankton bloom has been shown to be a key determinant of the flux of DMS to the atmosphere. Particular oceanic conditions due to the retreating ice-edge (e.g., a shallow mixed layer) can have an important effect on the timing of the phytoplankton bloom and thus the effux of DMS in this region. Model simulations support the view that algal taxonomy is not the most important factor determining DMS production in these waters. The mean vernal DMS flux is predicted to be 0.063 mg S m −2 d −1 which is in general agreement with previous summer season averages in the Arctic. DOI: 10.1034/j.1600-0889.1999.t01-4-00005.x","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81402614","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}

{"title":"Modelling forest growth and carbon storage in response to increasing CO 2 and temperature","authors":"M. Kirschbaum","doi":"10.3402/TELLUSB.V51I5.16500","DOIUrl":"https://doi.org/10.3402/TELLUSB.V51I5.16500","url":null,"abstract":"The response of plant growth to increasing climate change remains one of the unresolved issues in understanding the future of the terrestrial biosphere. It was investigated here by using the comprehensive forest growth model CenW 1.0.5 which integrates routines for the fluxes of carbon and water, interception of radiation and the cycling of nutrients. It was run with water and/or nutrient limitations on a background of naturally observed climate at Canberra, Australia. It was parameterised for Pinus radiata , the commercially most important plantation species in Australia. The simulations showed that under water-limited conditions, forest growth was highly sensitive to doubling CO 2 ,with growth increases of over 50% on average and even greater increases in dry years. In contrast, when water supply was adequate, but nutrients were limiting, growth increases were smaller, with an initial increase of about 15% during the first year after CO 2 was doubled. This growth increase diminished further over subsequent years so that after 20 years, there was virtually no remaining effect. This diminishing response was due to developing nutrient limitations caused by extra carbon input which immobilised nutrients in the soil. When both water and nutrients were adequate, growth was increased by about 15–20% with no decrease over time. Increasing ambient temperature had a positive effect on growth under nutrient limited conditions by stimulating nitrogen mineralisation rates, but had very little effect when nutrients were non-limiting. Responses were qualitatively similar when conditions were changed gradually. In response to increasing CO 2 by 2 µ mol mol −1 year −1 over 50 years, growth was increased by only 1% under nutrient-limited condition but by 16% under water-limited conditions. When temperature and CO 2 were both changed to emulate conditions between 1950 and 2030, growth was enhanced between 5 and 15% over the 80-year period due to the effect of CO 2 on photosynthesis and water economy especially under water-limited conditions, and due to the effect of increasing temperature in mineralising greater amounts of nutrients. These results show that there is not one universally applicable biological growth response to increasing temperature and CO 2 , but that they interact in complex ways with a number of other growth limiting factors. Any response factor of plants to CO 2 can only be quantified if the important interacting factors can be independently characterized for different situations. DOI: 10.1034/j.1600-0889.1999.t01-4-00002.x","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77088441","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}

{"title":"Anthropogenic versus natural sources of atmospheric sulphate from an Alpine ice core","authors":"M. Schwikowski, A. Döscher, H. Gäggeler, U. Schotterer","doi":"10.3402/TELLUSB.V51I5.16506","DOIUrl":"https://doi.org/10.3402/TELLUSB.V51I5.16506","url":null,"abstract":"Opposite to greenhouse gases, sulphate aerosol particles are expected to cause climate cooling, but uncertainties exist about source variability and strength. We analysed an ice core from a European glacier to quantify source strengths of aerosol-borne sulphate over a 200-year period. Sulphate from emissions of SO 2 increased by more than an order of magnitude during this century. This anthropogenic source is responsible for about 80% of total sulphate in the industrial period, and reflects emissions of west European countries. In the pre-industrial period mineral dust was the dominant contributor, followed by sulphate from SO 2 emissions with volcanoes or biomass burning as possible sources. DOI: 10.1034/j.1600-0889.1999.t01-4-00006.x","PeriodicalId":54432,"journal":{"name":"Tellus Series B-Chemical and Physical Meteorology","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85324143","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}