bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transport and chemical transformations influenced by shallow cumulus over land
Authors: Vilà-Guerau de Arellano J. , Kim S.-W. , Barth M. C. , Patton E. G. 
Published: April 2010

Abstract. The distribution and evolution of reactive species in a boundary layer characterized by the presence of shallow cumulus over land is studied by means of two large-eddy simulation models: the NCAR and WUR codes. The study focuses on two physical processes that can influence the chemistry: the enhancement of the vertical transport by the buoyant convection associated with cloud formation and the perturbation of the photolysis rates below, in and above the clouds. It is shown that the dilution of the reactant mixing ratio caused by the deepening of the atmospheric boundary layer is an important process and that it can decrease reactant mixing ratios by 10 to 50 percent compared to very similar conditions but with no cloud formation. Additionally, clouds transport chemical species to higher elevations in the boundary layer compared to the case with no clouds which influences the reactant mixing ratios of the nocturnal residual layers following the collapse of the daytime boundary layer. Estimates of the rate of reactant transport based on the calculation of the integrated flux divergence range from to −0.2 ppb hr−1 to −1 ppb hr−1, indicating a net loss of sub-cloud layer air transported into the cloud layer. A comparison of this flux to a parameterized mass flux shows good agreement in mid-cloud, but at cloud base the parameterization underestimates the mass flux. Scattering of radiation by cloud drops perturbs photolysis rates. It is found that these perturbed photolysis rates substantially (10–40%) affect mixing ratios locally (spatially and temporally), but have little effect on mixing ratios averaged over space and time. We find that the ultraviolet radiance perturbation becomes more important for chemical transformations that react with a similar order time scale as the turbulent transport in clouds. Finally, the detailed intercomparison of the LES results shows very good agreement between the two codes when considering the evolution of the reactant mean, flux and (co-)variance vertical profiles.
SCIAMACHY Level1 data: Calibration concept and in-flight calibration
Authors: Lichtenberg G. , Kleipool Q. , Krijger J. M. , van Soest G. , van Hees R. , Tilstra L. G. , Acarreta J. R. , Aben I. , Ahlers B. , Bovensmann H. , Chance K. , Gloudemans A. M. S. , Hoogeveen R. W. M. , Jongma R. , Noël S. , Piters A. , Schrijver H. , Schrijvers C. , Sioris C. E. , Skupin J. , Slijkhuis S. , Stammes P. , Wuttke M. 
Published: April 2010

Abstract. This paper discusses the basic concept of the calibration of the SCIAMACHY instrument and remaining open issues. SCIAMACHY is a scanning Limb/Nadir spectrometer covering the wavelength range from 212 nm to 2386 nm. It was launched on-board ENVISAT in February 2002. In general the instrument performance is excellent: It performs as tested on ground and there is only very minor degradation in time. The only exception is the unexpected formation of water ice on the infrared channels 7 and 8 that attenuates the signal and a light leak in channel 7. Both effects will be discussed. In the paper we will explain all individual calibration steps needed to come to a wavelength calibrated spectrum of the Earth reflectance. Open points in the calibrations and latest improvements, such as the new radiometric calibration will also be treated.
Non-volatile residuals of newly formed atmospheric particles in the boreal forest
Authors: Ehn M. , Petäjä T. , Birmili W. , Junninen H. , Aalto P. , Kulmala M. 
Published: April 2010

Abstract. The volatility of sub-micrometer atmospheric aerosol particles was studied in a rural background environment in Finland using a combination of a heating tube and a scanning mobility particle sizer. The analysis focused on nano-particles formed from nucleation bursts which were subsequently observed during their growth in the diameter range between 5 and 60 nm. During the 6 days of new particle formation shown in detail, the concentrations of newly formed particles increased up to 10 000 cm−3. The number of nucleation mode particles measured after volatilization in the heating tube at 280°C was up to 90% of the total number under ambient conditions. Taking into account the absolute accuracy of the size distribution measurements, all ambient particles found in the rural atmosphere could have a non-volatile core after volatilization at 280°C. As the regional new particle formation events developed over time as a result of further vapor condensation, the newly formed particles grew at an average growth rate of 2.4±0.3 nm h−1. Importantly, the non-volatile cores of nucleation mode particles were also observed to grow over time, however, at a lower average growth rate of 0.6±0.3 nm h−1. One implication of the volatility analysis is that the newly formed particles, which have reached ambient diameters of 15 nm, are unlikely to consist of sulfuric acid, ammonium sulfate, and water alone. A relatively constant ratio between the growth rate of the ambient particles as well as their non-volatile cores indicates that non-volatile matter is formed only gradually in the growing particles. The non-volatile fraction of the particles showed some correlation with the ambient temperature. The composition and formation mechanism of this non-volatile material in nucleation mode particles are, to date, not known.
Extinction coefficients retrieved in deep tropical ice clouds from lidar observations using a CALIPSO-like algorithm compared to in-situ measurements from the Cloud Integrated Nephelometer during CRYSTAL-FACE
Authors: Noel V. , Winker D. M. , Garrett T. J. , McGill M. 
Published: April 2010

Abstract. This paper presents a comparison of lidar ratios and volume extinction coefficients in tropical ice clouds, retrieved using observations from two instruments: the 532-nm Cloud Physics Lidar (CPL), and the in-situ Cloud Integrating Nephelometer (CIN) probe. Both instruments were mounted on airborne platforms during the CRYSTAL-FACE campaign and took measurements up to 17 km. Coincident observations from two cases of ice clouds located on top of deep convective systems are compared. First, lidar ratios are retrieved from CPL observations of attenuated backscatter, using a retrieval algorithm for opaque cloud similar to one used in the soon-to-be launched CALIPSO mission, and compared to results from the regular CPL algorithm. These lidar ratios are used to retrieve extinction coefficient profiles, which are compared to actual observations from the CIN in-situ probe, putting the emphasis on their vertical variability. When observations coincide, retrievals from both instruments are very similar. Differences are generally variations around the average profiles, and general trends on larger spatial scales are usually well reproduced. The two instruments agree well, with an average difference of less than 11% on optical depth retrievals. Results suggest the CALIPSO Deep Convection algorithm can be trusted to deliver realistic estimates of the lidar ratio, leading to good retrievals of extinction coefficients.
MIPAS Level 1B algorithms overview: operational processing and characterization
Authors: Kleinert A. , Aubertin G. , Perron G. , Birk M. , Wagner G. , Hase F. , Nett H. , Poulin R. 
Published: April 2010

Abstract. This paper gives an overview of the MIPAS Level 1B (L1B) processor whose main objective is to calibrate atmospheric measurements radiometrically, spectrally and geo-located. It presents also the results of instrument characterization done during the first years in-flight. MIPAS has shown very good performance and stability.
Source apportionment of submicron organic aerosols at an urban site by linear unmixing of aerosol mass spectra
Authors: Lanz V. A. , Alfarra M. R. , Baltensperger U. , Buchmann B. , Hueglin C. , Prévôt A. S. H. 
Published: April 2010

Abstract. Submicron ambient aerosol was characterized in summer 2005 at an urban background site in Zurich, Switzerland, during a three-week measurement campaign. Highly time-resolved samples of non-refractory aerosol components were analyzed with an Aerodyne aerosol mass spectrometer (AMS). Positive matrix factorization (PMF) was used for the first time for AMS data to identify the main components of the total organic aerosol and their sources. The PMF retrieved factors were compared to measured reference mass spectra and were correlated with tracer species of the aerosol and gas phase measurements from collocated instruments. Six factors were found to explain virtually all variance in the data and could be assigned either to sources or to aerosol components such as oxygenated organic aerosol (OOA). Our analysis suggests that at the measurement site only a small (<10%) fraction of organic PM1 originates from freshly emitted fossil fuel combustion. Other primary sources identified to be of similar or even higher importance are charbroiling (10–15%) and wood burning (~10%), along with a minor source interpreted to be influenced by food cooking (6%). The fraction of all identified primary sources is considered as primary organic aerosol (POA). This interpretation is supported by calculated ratios of the modelled POA and measured primary pollutants such as elemental carbon (EC), NOx, and CO, which are in good agreement to literature values. A high fraction (60–69%) of the measured organic aerosol mass is OOA which is interpreted mostly as secondary organic aerosol (SOA). This oxygenated organic aerosol can be separated into a highly aged fraction, OOA I, (40–50%) with low volatility and a mass spectrum similar to fulvic acid, and a more volatile and probably less processed fraction, OOA II (on average 20%). This is the first publication of a multiple component analysis technique to AMS organic spectral data and also the first report of the OOA II component.
The quantitative infrared and NIR spectrum of CH2I2 vapor: vibrational assignments and potential for atmospheric monitoring
Authors: Johnson T. J. , Masiello T. , Sharpe S. W. 
Published: April 2010

Abstract. Diiodomethane (CH2I2) photolysis in the presence of ozone is a suggested precursor to new particle aerosol formation, particularly in coastal areas. As part of the PNNL database of gas-phase infrared spectra, the quantitative absorption spectrum of CH2I2 has been acquired at 0.1 cm−1 resolution. Two strong b2 symmetry A-type bands at 584 and 1114 cm−1 are observed, but are not resolved at 760 Torr and appear as B-type. In contrast, the b1 symmetry C-type bands near 5953, 4426 and 3073 cm−1 are resolved with rotational structure, including Q-branches with widths ≤1 cm−1. The quantitative infrared and near-infrared vapor-phase spectra (600–10 000 cm−1) are reported for the first time and discussed in terms of atmospheric monitoring. FT-Raman spectra and ab initio calculations are used to complete vibrational assignments in the C2v point group.
Evaluated kinetic and photochemical data for atmospheric chemistry: Volume III – reactions of inorganic halogens
Authors: Atkinson R. , Baulch D. L. , Cox R. A. , Crowley J. N. , Hampson R. F. , Hynes R. G. , Jenkin M. E. , Rossi M. J. , Troe J. 
Published: April 2010

Abstract. This article, the third in the series, presents kinetic and photochemical data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of inorganic halogen species, which were last published in J. Phys. Chem. Ref. Data in 2000 (Atkinson et al., 2000), and were updated on the IUPAC website in 2003. The article consists of a summary sheet, containing the recommended kinetic parameters for the evaluated reactions, and five appendices containing the data sheets, which provide information upon which the recommendations are made.
Combined observational and modeling based study of the aerosol indirect effect
Authors: Storelvmo T. , Kristjansson J. E. , Myhre G. , Johnsrud M. , Stordal F. 
Published: April 2010

Abstract. The indirect effect of aerosols via liquid clouds is investigated by comparing aerosol and cloud characteristics from the Global Climate Model CAM-Oslo to those observed by the MODIS instrument onboard the TERRA and AQUA satellites (http://modis.gsfc.nasa.gov). The comparison is carried out for 15 selected regions ranging from remote and clean to densely populated and polluted. For each region, the regression coefficient and correlation coefficient for the following parameters are calculated: Aerosol Optical Depth vs. Liquid Cloud Optical Thickness, Aerosol Optical Depth vs. Liquid Cloud Droplet Effective Radius and Aerosol Optical Depth vs. Cloud Liquid Water Path. Modeled and observed correlation coefficients and regression coefficients are then compared for a 3-year period starting in January 2001. Additionally, global maps for a number of aerosol and cloud parameters crucial for the understanding of the aerosol indirect effect are compared for the same period of time. Significant differences are found between MODIS and CAM-Oslo both in the regional and global comparison. However, both the model and the observations show a positive correlation between Aerosol Optical Depth and Cloud Optical Depth in practically all regions and for all seasons, in agreement with the current understanding of aerosol-cloud interactions. The correlation between Aerosol Optical Depth and Liquid Cloud Droplet Effective Radius is variable both in the model and the observations. However, the model reports the expected negative correlation more often than the MODIS data. Aerosol Optical Depth is overall positively correlated to Cloud Liquid Water Path both in the model and the observations, with a few regional exceptions.
The water vapour distribution in the Arctic lowermost stratosphere during LAUTLOS campaign and related transport processes including stratosphere-troposphere exchange
Authors: Karpechko A. , Lukyanov A. , Kyrö E. , Khaikin S. , Korshunov L. , Kivi R. , Vömel H. 
Published: April 2010

Abstract. Balloon-borne water vapour measurements during January and February 2004, which were obtained as part of the LAUTLOS campaign at Sodankylä, Finland, 67° N, were used to analyse the water vapour distribution in the wintertime Arctic lowermost stratosphere. A 2.5 km thick layer (or 30 K in the potential temperature scale) above the local tropopause is characterized by a significant water vapour variability on a synoptic timescale with values between stratospheric and tropospheric, which is in good agreement with previously reported measurements. A cross-correlation analysis of ozone and water vapour confirms that this layer contains a mixture of stratospheric and tropospheric air masses. Some of the flights sampled laminae of enhanced water vapour above the tropopause. Meteorological analyses and backward trajectory calculations show that these features are related to filaments that had developed along the flanks of cut-off anticyclones, which had been active at this time over the Northern Atlantic. Cross-tropopause mass fluxes calculated following the Wei method are used to identify regions and processes that are important for stratosphere-troposphere exchange (STE) in high-latitudes. Intensive STE occurs around cut-off anticyclones in regions of strong winds, where calculations suggest the presence of developed clear-air turbulence. The decay of the filaments is also shown to be important for STE.
A global emission inventory of carbonaceous aerosol from historic records of fossil fuel and biofuel consumption for the period 1860–1997
Authors: Junker C. , Liousse C. 
Published: April 2010

Abstract. Country by country emission inventories for carbonaceous aerosol for the period 1860 to 1997 have been constructed on the basis of historic fuel production, use and trade data sets published by the United Nation's Statistical Division UNSTAT (1997), Etemad et al. (1991) and Mitchell (1992, 1993, 1995). The inventories use emission factors variable over time, which have been determined according to changes in technological development. The results indicate that the industrialisation period since 1860 was accompanied by a steady increase in black carbon (BC) and organic carbon (OC) emissions up to 1910. The calculations show a moderate decrease of carbonaceous aerosol emissions between 1920 and 1930, followed by an increase up to 1990, the year when emissions began to decrease again. Changes in BC and OC emissions prior to the year 1950 are essentially driven by the USA, Germany and the UK. The USSR, China and India become substantial contributors to carbonaceous aerosol emissions after 1950. Emission maps have been generated with a 1°×1° resolution based on the relative population density in each country. They will provide a helpful tool for assessing the effect of carbonaceous aerosol emissions on observed climate changes of the past.
The atmospheric cycling of radiomethane and the ''fossil fraction'' of the methane source
Authors: Lassey K. R. , Lowe D. C. , Smith A. M. 
Published: April 2010

Abstract. The cycling of 14CH4 (''radiomethane'') through the atmosphere has been strongly perturbed in the industrial era by the release of 14C-free methane from geologic reservoirs (''fossil methane'' emissions), and in the nuclear era, especially since ca 1970, by the direct release of nucleogenic radiomethane from nuclear power facilities. Contemporary measurements of atmospheric radiomethane have been used to estimate the proportion of fossil methane in the global methane source (the ''fossil fraction''), but such estimates carry high uncertainty due to the ill-determined nuclear-power source. We exploit an analysis in a companion paper of the global radiomethane budget through the nuclear era, using contemporary measurements of atmospheric radiomethane since 1986 to quantify both the fossil fraction and the strength of the nuclear power source. We deduce that 28.6±1.9% (1 s.d.) of the global methane source has fossil origin, a fraction which may include some 14C-depleted refractory carbon fraction such as in aged peat deposits. The co-estimated strength of the global nuclear-power source of radiomethane is consistent with values inferred independently from local nuclear facilities.
Water-side turbulence enhancement of ozone deposition to the ocean
Authors: Fairall C. W. , Helmig D. , Ganzeveld L. , Hare J. 
Published: April 2010

Abstract. A parameterization for the deposition velocity of an ocean-reactive atmospheric gas (such as ozone) is developed. The parameterization is based on integration of the turbulent-molecular transport equation (with a chemical source term) in the ocean. It extends previous work that only considered reactions within the oceanic molecular sublayer. The sensitivity of the ocean-side transport to reaction rate and wind forcing is examined. A more complicated case with a much more reactive thin surfactant layer is also considered. The full atmosphere-ocean deposition velocity is obtained by matching boundary conditions at the interface. For an assumed ocean reaction rate of 103 s-1, the enhancement for ozone deposition by oceanic turbulence is found to be up to a factor of three for meteorological data obtained in a recent cruise off the East Coast of the U.S.
Formation of secondary organic aerosol and oligomers from the ozonolysis of enol ethers
Authors: Sadezky A. , Chaimbault P. , Mellouki A. , Römpp A. , Winterhalter R. , Le Bras G. , Moortgat G. K. 
Published: April 2010

Abstract. Formation of secondary organic aerosol has been observed in the gas phase ozonolysis of a series of enol ethers, among them several alkyl vinyl ethers (AVE, ROCH=CH2), such as ethyl, propyl, n-butyl, iso-butyl, t-butyl vinyl ether, and ethyl propenyl ether (EPE, C2H5OCH=CHCH3). The ozonolysis has been studied in a 570 l spherical glass reactor at atmospheric pressure (730 Torr) and temperature (296 K). Gas phase reaction products were investigated by in-situ FTIR spectroscopy, and secondary organic aerosol (SOA) formation was monitored by a scanning mobility particle sizer (SMPS). The chemical composition of the formed SOA was analysed by a hybrid mass spectrometer using electrospray ionization (ESI). The main stable gas phase reaction product is the respective alkyl formate ROC(O)H, formed with yields of 60 to 80%, implying that similar yields of the corresponding Criegee Intermediates (CI) CH2O2 for the AVE and CH3CHO2 for EPE are generated. Measured SOA yields are between 2 to 4% for all enol ethers. Furthermore, SOA formation is strongly reduced or suppressed by the presence of an excess of formic acid, which acts as an efficient CI scavenger. Chemical analysis of the formed SOA by ESI(+)/MS-TOF allows to identify oligomeric compounds in the mass range 200 to 800 u as its major constituents. Repetitive chain units are identified as CH2O2 (mass 46) for the AVE and C2H4O2 (mass 60) for EPE and thus have the same chemical compositions as the respective major Criegee Intermediates formed during ozonolysis of these ethers. The oligomeric structure and chain unit identity are confirmed by HPLC/ESI(+)/MS-TOF and ESI(+)/MS/MS-TOF experiments, whereby successive and systematic loss of a fragment with mass 46 for the AVE (and mass 60 for EPE) is observed. It is proposed that the oligomer has the following basic structure of an oligoperoxide, -[CH(R)-O-O]n-, where R=H for the AVE and R=CH3 for the EPE. Oligoperoxide formation is thus suggested to be another, so far unknown reaction of stabilized Criegee Intermediates in the gas phase ozonolysis of oxygen-containing alkenes leading to SOA formation.
Radiocarbon analysis in an Alpine ice core: record of anthropogenic and biogenic contributions to carbonaceous aerosols in the past (1650–1940)
Authors: Jenk T. M. , Szidat S. , Schwikowski M. , Gäggeler H. W. , Brütsch S. , Wacker L. , Synal H.-A. , Saurer M. 
Published: April 2010

Abstract. Long-term concentration records of carbonaceous particles (CP) are of increasing interest in climate research due to their not yet completely understood effects on climate. Nevertheless, only poor data on their concentrations and sources in the past is available. We present a first long-term record of organic carbon (OC) and elemental carbon (EC) concentrations - the two main fractions of CP – along with the corresponding fraction of modern carbon (fM) derived from radiocarbon (14C) analysis. The combination of concentration measurements with 14C analysis of CP allows a distinction and quantification of natural, biogenic and anthropogenic fossil sources in the past. CP were extracted from an ice archive, with resulting carbon quantities in the microgram range. Analysis of 14C by accelerator mass spectrometry (AMS) was therefore highly demanding. We analysed 33 samples of 0.4 to 1 kg ice from a 150.5 m long ice core retrieved at Fiescherhorn glacier in December 2002 (46°33'3.2" N, 08°04'0.4'' E; 3900 m a.s.l.). Samples were taken from below the firn/ice transition down to bedrock, covering the time period 1650–1940 and thus the transition from the pre-industrial to the industrial era. Before 1800, OC was of pure biogenic origin with a mean concentration of 21±2 μg kg−1}. In 1940, OC concentration was more than a factor of 3 higher than this biogenic background, almost half of it originating from anthropogenic sources, i.e. from combustion of fossil fuels. The biogenic EC concentration was nearly constant over the examined time period with 6±1 μg kg−1. In 1940, the additional anthropogenic input of atmospheric EC was about 50 μg kg−1.