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Atmospheric Environment (v.40, #39)

Editorial board (pp. i).

Indoor microclimate, ozone and nitrogen oxides in two medieval churches in Cyprus by G. Loupa; E. Charpantidou; I. Kioutsioukis; S. Rapsomanikis (pp. 7457-7466).

A number of indoor atmosphere parameters that may affect the preservation of artefacts in two churches in Cyprus, were studied. Temperature, relative humidity (RH), total ultra-violet and total solar radiation, that were continuously recorded during two campaigns (summer and winter), exhibited large diurnal and seasonal variations. Indoor concentrations of nitrogen oxides, determined at the same periods, also exhibited diurnal dependence on air exchange rate (AER) and on their indoor sources from the burning of candles and oil lamps. Indoor concentrations of ozone exhibited dependence on the AER and on the concentration of other indoor pollutants. On a large number of occasions these concentrations exceeded the proposed air quality standards for the preservation of works of art in both churches.

Keywords: Indoor air quality; Church; Indoor climate; Ozone; Nitrogen oxides

Seasonal estimation of organic mass to organic carbon in PM_2.5 at rural and urban locations in New York state by M.-S. Min-Suk Bae; Kenneth L. Demerjian; James J. Schwab (pp. 7467-7479).

Estimates of the seasonality of the ratio of fine particulate organic matter (OM) to fine particulate organic carbon (OC) are determined for data collected at the Pinnacle State Park (PSP) in rural upstate New York and at Queens College (QC) in New York City over a 3 year period from 2002 through 2004. The reconstructed mass balance method, which assigns as organic matter all of the fine particulate matter mass that cannot be attributed to sulfate ion, nitrate ion, ammonium ion, elemental carbon, water and metal oxides, is used for estimating the OM/OC ratio and assessing the seasonal variations in OM/OC ratio. The organic mass concentrations measured by an Aerosol Mass Spectrometer (AMS) for a much shorter period are compared to organic mass by the reconstructed mass balance as a check on the method.The time series of the seasonal estimates for the OM/OC ratio indicates that the 3-year-average falls between 1.5 and 1.9 at the PSP site for this period. The warm season average OM/OC ratios of 2.1 are slightly higher than cold season. The urban site OM/OC ratio does not vary systematically with season and falls between 1.3 and 1.6.

Keywords: Carbonaceous aerosol; Elemental carbon; Fine particulate matter; Mass balance

Application of multiple wind-roses to improve the modelling of ground-level ozone in the UK by J. Strong; J.D. Whyatt; C.N. Hewitt (pp. 7480-7493).

The Edinburgh Lancaster Model for Ozone (ELMO) has been previously used to predict ground-level ozone concentrations in the UK. Here we make significant improvements to its modelling performance by the application of more representative meteorology. We find that when ELMO is used with a series of distance weighted (DW) wind-roses, distributed across the whole of the UK, it closely predicts the 98th percentile of the annual hourly ozone concentration typical of summertime ozone episodes as validated against observations at 15 rural monitoring sites. There is, however, still some over-prediction of this metric in urban and sub-urban areas impacted by large emissions of NO _x. We use ELMO with DW wind-roses to predict the effects of reductions of precursor emissions on ozone concentrations and demonstrate the extent to which the UK Air Quality Standard (AQS) for ozone is likely to be exceeded across the country in 2010.

Keywords: ELMO; Master Chemical Mechanism; Summertime peak ozone; Air Quality Standards

Effective doses in schools based on nanosize radon progeny aerosols by Vaupotic Janja Vaupoti�?; Ivan Kobal (pp. 7494-7507).

Indoor air concentrations of radon and radon short-lived decay products, equilibrium factors, unattached fractions of radon short-lived decay products ( f_un), relative humidity and temperature have been measured in Slovenian schools, with an emphasis on f_un as the crucial parameter in dose assessment. The following geometric mean and geometric standard deviation values, respectively, were obtained: C_Rn: 700Bqm⁻³ and 3.29; C_RnDP: 441Bqm⁻³ and 3.07; F: 0.59 and 1.30; and f_un: 0.12 and 1.43. Dose conversion factors, based on the measured f_un values were compared to epidemiology based value of 5mSv/WLM.

Keywords: Radon; Radon short-lived decay products; Unattached fraction; Equilibrium factor; Dose conversion factor; Schools

The first VOC intercomparison exercise within the Global Atmosphere Watch (GAW) by Rappengluck B. Rappenglück; E. Apel; M. Bauerfeind; J. Bottenheim; P. Brickell; Cavolka P. Čavolka; J. Cech; L. Gatti; H. Hakola; J. Honzak; R. Junek; D. Martin; C. Noone; Plass-Dulmer Ch. Plass-Dülmer; D. Travers; D. Wang (pp. 7508-7527).

In 2003 the World Calibration Centre for volatile organic compounds (WCC-VOC) which forms part of the Global Atmosphere Watch (GAW) program coordinated the first comprehensive intercomparison exercise among the GAW-VOC community. The intercomparison focused on a synthetic C₂–C₁₁ VOC standard mixture in nitrogen (N₂) and involved nine different stations/laboratories (10 instruments) from seven countries (Brazil, Canada [two labs], Czech Republic, Finland, Germany [two labs; three instruments], Ireland, and Slovakia), representing four measurement programs (GAW, EMEP, CAPMoN, LBA). These sites either run canister or online measurements. WCC-VOC provided each participant of the intercomparison exercise with standard gas canisters which contained 73 VOCs prepared and certified by the National Center for Atmospheric Research (NCAR), Boulder. The participating laboratories were expected to identify and quantify as many compounds of the WCC-VOC standard canister as possible based on their routine identification and calibration methods. The primary objective of this first intercomparison was to examine the current performance status of the analytical facilities of each laboratory and to check whether the results meet the Data Quality Objectives (DQO) developed by WCC-VOC. An additional objective was to establish a ranking of properly determined compounds among all laboratories in order to identify compounds which could be most accurately determined by all laboratories.Due to the variety of sampling and analytical methods among the participants both the number of identified species (16–150 VOCs) and their proper quantification differed largely. Focusing on a subset of 28 VOCs recognized as primary GAW target compounds the results show that the DQOs for repeatability are met in most cases. However for the deviation from the WCC-VOC reference values the picture is different. For some VOCs the concentrations differed significantly among the different laboratories. In terms of both uncertainty and repeatability a significant number of atmospherically relevant VOCs (e.g. propane, propylene, isoprene, and benzene) are properly determined by most labs. However, difficulties occur with other important VOCs (e.g. acetylene, i-pentane, toluene). From this subset of VOC results it appears imperative to strengthen harmonization procedures particular with regard to real air samplings. These processes have been initiated and include more frequent intercomparisons also covering ambient air samples, individual performance audits, and a future networkwide calibration standard.

Keywords: GAW; VOC; Intercomparison; Canister

Dry deposition and resuspension of particle-associated metals near a freeway in Los Angeles by Lisa D. Sabin; Jeong Hee Lim; Maria Teresa Venezia; Arthur M. Winer; Kenneth C. Schiff; Keith D. Stolzenbach (pp. 7528-7538).

Dry atmospheric deposition represents a potentially large source of pollutant metal contamination in urban stormwater runoff, yet there is a limited amount of research on the relationship between atmospheric emissions and water quality problems in urban areas. In Los Angeles, with air quality that ranks among the worst in the United States, significant quantities of toxic materials are released into the atmosphere every day, and paved road dust represents the largest source of particle-associated metal emissions to the atmosphere. In order to better understand the role of roadways as a source of localized metal deposition, we characterized the horizontal dry deposition patterns of chromium, copper, lead, nickel and zinc upwind and at increasing distances downwind of the I-405 Freeway in coastal Los Angeles. Dry deposition fluxes and atmospheric concentrations of these metals were highest at the site closest to the freeway, and reduced to approximately urban background concentrations between 10 and 150m downwind of the freeway. Compared with urban background, atmospheric particle size distributions indicated the freeway was a significant source of these metals on large particles >6μm in diameter, which deposit close to their source and account for the increased dry deposition flux rates observed near the freeway. The spatial pattern of measured deposition flux was well predicted by a relatively simple line-source Gaussian plume model modified to include particle deposition and resuspension. The model results indicated dilution by vertical dispersion of the plume was the most important mechanism regulating downwind concentrations and deposition.

Keywords: Atmospheric deposition; Large particles; Urban runoff; Paved road dust

Carbon isotopic characterization of dissolved organic carbon in rainwater: Terrestrial and marine influences by G.B. Avery Jr.; J.D. Willey; R.J. Kieber (pp. 7539-7545).

This study presents the first published¹⁴C and¹³C isotopic data for dissolved organic carbon (DOC) in rainwater. The¹⁴C fraction modern ( Fm) values for rain DOC ranged from 0.9051 to 1.0569. Between 4% and 24% of the rainwater DOC was of fossil fuel origin based on a two end member calculation assuming biogenic carbon has the same¹⁴C content as the contemporary atmosphere ( Fm=1.11–1.19) and fossil fuel carbon is devoid of¹⁴C. The δ¹³C content of rain DOC ranged from −21.8‰ to −28.2‰ spanning the terrestrial and fossil fuels average (∼−26‰) to marine (−18‰ to −20‰) values. Rain events with more continental influences had δ¹³C values closer to the terrestrial and fossil fuels signal and higher concentrations of fossil fuel derived DOC. Rain events with stronger oceanic influences had δ¹³C values shifting towards those typical of marine systems and had lower concentrations of fossil fuel derived DOC. The influence air mass back trajectory has on the terrestrial and marine characteristics of rainwater DOC identifies air mass recent history as an important factor controlling the sources of DOC in precipitation. It also indicates water soluble volatile organic carbon (VOC's) have relatively short residence times on the order of days with minimal global transport. However, residence times of days, and the presence of both marine and terrestrial DOC in rainwater, suggests that precipitation represents an important exchange of carbon between land and the oceans especially in coastal regions.

Keywords: Rain precipitation; Dissolved organic carbon; Isotopes; ¹³; C; ¹⁴; C

Linear regression techniques for use in the EC tracer method of secondary organic aerosol estimation by Rick D. Saylor; Eric S. Edgerton; Benjamin E. Hartsell (pp. 7546-7556).

A variety of linear regression techniques and simple slope estimators are evaluated for use in the elemental carbon (EC) tracer method of secondary organic carbon (OC) estimation. Linear regression techniques based on ordinary least squares are not suitable for situations where measurement uncertainties exist in both regressed variables. In the past, regression based on the method of Deming [1943. Statistical Adjustment of Data. Wiley, London] has been the preferred choice for EC tracer method parameter estimation. In agreement with Chu [2005. Stable estimate of primary OC/EC ratios in the EC tracer method. Atmospheric Environment 39, 1383–1392], we find that in the limited case where primary non-combustion OC (OC_non-comb) is assumed to be zero, the ratio of averages (ROA) approach provides a stable and reliable estimate of the primary OC–EC ratio, (OC/EC)_pri. In contrast with Chu [2005. Stable estimate of primary OC/EC ratios in the EC tracer method. Atmospheric Environment 39, 1383–1392], however, we find that the optimal use of Deming regression (and the more general York et al. [2004. Unified equations for the slope, intercept, and standard errors of the best straight line. American Journal of Physics 72, 367–375] regression) provides excellent results as well.For the more typical case where OC_non-comb is allowed to obtain a non-zero value, we find that regression based on the method of York is the preferred choice for EC tracer method parameter estimation. In the York regression technique, detailed information on uncertainties in the measurement of OC and EC is used to improve the linear best fit to the given data. If only limited information is available on the relative uncertainties of OC and EC, then Deming regression should be used. On the other hand, use of ROA in the estimation of secondary OC, and thus the assumption of a zero OC_non-comb value, generally leads to an overestimation of the contribution of secondary OC to total measured OC.

Keywords: Deming; York; Least-squares; Ordinary linear regression; Organic carbon

Deposition velocity of O₃ and SO₂ in the dry and wet season above a tropical forest in northern Thailand by Kazuhide Matsuda; Ichiro Watanabe; Vitsanu Wingpud; Phunsak Theramongkol; Tsuyoshi Ohizumi (pp. 7557-7564).

In order to investigate ozone (O₃) and sulfur dioxide (SO₂) dry deposition above a forest in a tropical savanna climate in Southeast Asia, field experiments were performed in a teak deciduous forest in Mea Moh, Lampang Province, located in northern Thailand. O₃ and SO₂ fluxes were observed on the basis of the aerodynamic gradient method. The experimental period from January to August in 2004 covered the dry (Jan–Apr) and wet (May–Aug) seasons. Both gas concentrations increased in the dry season and decreased in the wet season. Interval estimation of average with a confidence interval of 95% on the deposition velocity data between 25 and 75 percentiles was performed. The intervals of average O₃ deposition velocity were estimated to be 0.37–0.39cms⁻¹ (daytime) and 0.12–0.13cms⁻¹ (nighttime) in the dry season; and 0.62–0.65cms⁻¹ (daytime) and 0.25–0.27cms⁻¹ (nighttime) in the wet season. The intervals of average SO₂ deposition velocity were estimated to be 0.10–0.31cms⁻¹ (daytime) and 0.08–0.11cms⁻¹ (nighttime) in the dry season; and 0.95–1.39cms⁻¹ (daytime) and 0.26–0.42cms⁻¹ (nighttime) in the wet season. SO₂ deposition velocity in the rain period was significantly higher than that in the no-rain period. Higher deposition velocities in the wet season were mainly caused by non-stomatal uptake of wet canopy due to a lot of wet days, especially in the case of SO₂. Much higher daytime deposition velocities in the wet season were additionally caused by stomatal uptake of leafy trees. The applicability of Wesely's parameterization of deposition velocity to a tropical savanna climate was examined. In both gases, the input resistance of transitional spring to the dry season and that of midsummer to the wet season could be applied as a first approximation, although strictly the parameterization of O₃ non-stomatal resistance needs modification in the dry-season daytime. The applicability of some other parameterizations was also considered. Including the enhanced effect of wet canopy uptake in the non-stomatal resistance was essential in parameterizing SO₂ deposition velocity in the wet season of the region.

Keywords: Dry deposition; Deposition velocity; Ozone; Sulfur dioxide; Southeast Asia

Flow characteristics and particle mass and number concentration variability within a busy urban street canyon by Stephan Weber; Wilhelm Kuttler; Konradin Weber (pp. 7565-7578).

Mean and turbulent flow characteristics together with particle concentrations were measured in a busy urban street canyon in Essen, Germany, at five (flow characteristics) and three heights (particles) above ground, respectively. Particle mass and number concentrations were sampled in the size range 0.3< D_p<10μm. The flow characteristics within the canyon were significantly influenced by canyon geometry and were shown to have significant impact on particle concentrations. During flow being directed perpendicular to the canyon a vortex circulation leads to a doubling of ambient particles when the measurement site is situated upwind to ambient flow. The vertical profiles of fine particles have maximum vertical differences of 12% between measurement levels. In the upper part of the canyon, concentrations decrease due to enhanced turbulence and mixing. Significant differences in the dynamics of particle number concentration for different size ranges are analysed. While submicron particles are inversely related to turbulence parameters, i.e. lower concentrations during enhanced turbulence, coarser particles (1< D_p<10μm) are positively correlated to mixing within the canyon.

Keywords: Fine particles; Turbulence; Mean flow; Vertical profile; Urban street canyon

Role of the binary H₂SO₄–H₂O homogeneous nucleation in the formation of volatile nanoparticles in the vehicular exhaust by Hua Du; Fangqun Yu (pp. 7579-7588).

High concentration of volatile nanoparticles (NPs) formed in vehicular exhaust may lead to adverse health effects, and a clear understanding of the nucleation mechanisms of these particles remains to be achieved. We investigate the role of H₂SO₄–H₂O binary homogeneous nucleation (BHN) in the formation of NPs in the diluting vehicular exhaust, using a recently developed kinetic H₂SO₄–H₂O BHN model suitable for studying the nucleation process in rapidly diluting exhaust. For the vehicles running on the fuel with fuel sulfur content (FSC) of ∼330ppm we found that BHN may significantly contribute to the NP formation, especially when the ambient temperature is low and the relative humidity is high. Our simulations show that BHN rate is very sensitive to FSC and sulfur to sulfuric acid conversion efficiency ( ε_s). For ε_s value of 1%, BHN is negligible under typical conditions when FSC is <∼100ppm. However, NP formation via BHN may still be significant if ε_s >∼4% even after FSC is reduced to below ∼50ppm. The sensitivities of NP formation via BHN to key factors (including ambient temperature and relative humidity, FSC, ε_s and the soot number concentration) are presented.

Keywords: Nanoparticles; Fuel sulfur content; Vehicle exhaust; Kinetic quasi-unary nucleation model

Characteristics of polycyclic aromatic hydrocarbon (PAH) emissions from a UH-1H helicopter engine and its impact on the ambient environment by Y.-C. Yu-Cheng Chen; W.-J. Wen-Jhy Lee; S.-N. Shi-Nian Uang; S.-H. Su-Hsing Lee; P.-J. Perng-Jy Tsai (pp. 7589-7597).

The objective of this study is to characterize the emissions of polycyclic aromatic hydrocarbons (PAHs) from a UH-1H helicopter turboshaft engine and its impact on the ambient environment. Five power settings of the ground idle (GI), fly idle (FI), beed band check (BBC), inlet guide vane (IGV), and take off (TO) were selected and samples were collected from the exhaust by using an isokinetic sampling system. Twenty-two PAH compounds were analyzed by gas chromatograph (GC)/MS. We found the mean total PAH concentration in the exhaust of the UH-1H engine (843μgm⁻³) is 1.05−51.7 times in magnitude higher than those of the heavy-duty diesel (HDD) engine, motor vehicle engine, and F101 aircraft engine. Two- and three-ringed PAHs account for 97.5% of total PAH emissions from the UH-1H engine. The mean total PAH and total BaP_eq emission factors for the UH-1H engine (63.4 and 0.309mgL⁻¹·fuel) is 1.65−23.4 and 1.30−7.54 times in magnitude higher than those for the motor vehicle engine, HDD engine, and F101 aircraft engine. The total emission level of the single PAH compound, BaP, for the UH-1H engine (EL_BaP) during one landing and take off (LTO) cycle (2.19mgLTO⁻¹) was higher than the European Commission standard (1.24mgLTO⁻¹) suggesting that appropriate measures should be taken to reduce PAH emissions from UH-1H engines in the future.

Keywords: Helicopter engine; Polycyclic aromatic hydrocarbons; Emissions factor; Emission characteristic

Ozone photochemistry and elevated isoprene during the UK heatwave of august 2003 by James D. Lee; Alastair C. Lewis; Paul S. Monks; Mark Jacob; Jacqueline F. Hamilton; James R. Hopkins; Nicola M. Watson; Julie E. Saxton; Christopher Ennis; Lucy J. Carpenter; Nicola Carslaw; Zoe Fleming; Brian J. Bandy; David E. Oram; Stuart A. Penkett; Jana Slemr; Emily Norton; Andrew R. Rickard; Lisa K Whalley; Dwayne E. Heard; William J. Bloss; Thomas Gravestock; Shona C. Smith; Jenny Stanton; Michael J. Pilling; Michael E. Jenkin (pp. 7598-7613).

A wide range of chemical and physical parameters has been observed over the course of a severe Europe-wide air pollution episode in August 2003. Detailed surface observations made at the rural perimeter edge of London, UK, indicated significantly elevated levels of primary volatile organic compounds (VOCs), ozone (>110ppbV), other photochemical by-products such as PAN, HCHO, and oxygenates but not NO _x. Reactive tracers in combination with Doppler wind radar and back trajectories have been used to establish that initial morning rises in O₃ during the episode were caused by entrainment of air from aloft, polluted on regional scales from mainland Europe. Total VOC reactivity to OH approximately doubled during this episode, with similar distribution between functional groups, but showing a temperature dependent contribution from biogenic isoprene (maximum 1.2ppbv). Under episodic conditions total peroxy radicals in excess of 60pptv were observed in late afternoon with strong correlation to a later and higher peak in ozone. Episodic alkyl peroxy radicals were calculated to be substantially influenced by peroxy acetyl, via the thermal dissociation of PAN at high temperatures.

Keywords: Ozone; Isoprene; Pan; Air quality; Peroxyradicals; Non-methane hydrocarbons; Regional transport

Chemical characterisation of single airborne particles in Athens (Greece) by ATOFMS by Manuel Dall’Osto; Roy M. Harrison (pp. 7614-7631).

A TSI Model 3800 aerosol time-of-flight mass spectrometer (ATOFMS) was deployed for single-particle analysis to Athens (Greece) during August 2003. It has revealed particle types not previously reported in urban air, as well as adding appreciably to the knowledge of aerosol in the Athens atmosphere. Sampling was carried out on a minor road in the city centre and the mass spectra of 166,603 particles were recorded, with 128,290 presenting both positive and negative spectra. The ART-2a neural network algorithm was applied and five main classes of particle were characterised: sea salt, dust, carbon, inorganic and K-rich, with sub-classes within each. Dust (with five sub-classes) was the main class, accounting for up to 49.5% of the particles characterised. Oxygenated organic particles feature heavily in the dataset and some are internally mixed with nitrate and sulphate. Most of the carbon-containing particles appeared to be a secondary product of atmospheric chemistry and one specific class (C-SEC_2) peaked every night at 22:00, when temperature and RH values favoured condensation. The secondary particles showed clear internal mixing of organic and inorganic constituents in contrast to their common theoretical treatment as external mixtures. The apparent semi-volatility of one class was striking. Compared with measurements in northern Europe, the abundance of relatively coarse dust particles and of secondary organic particles is notable. The particle classes derived from analysis of the ATOFMS data were compared with published data on the composition of aerosol in Athens. The latter is largely restricted to major water-soluble ions, and the two measurement techniques proved to be highly complementary.

Keywords: ATOFMS; Single-particle analysis; Athens; Dust; Secondary aerosol

Odour emission factors for the prediction of odour emissions from plants for the mechanical and biological treatment of MSW by Selena Sironi; Laura Capelli; Centola Paolo Céntola; Renato Del Rosso; Massimiliano Il Grande (pp. 7632-7643).

In this study, the results of odour concentration measurements sampled from the principal odour sources of 40 dimensionally different and representative Italian waste mechanical and biological treatment (MBT) plants are presented. Experimental data are then used to estimate the odour emission factors (OEFs) relevant to single-process steps. An OEF is a representative value that relates the quantity of odour released to the atmosphere to a specific activity index, which may be for example the waste treatment capacity, the gross weight production, the site surface or a time unit. In this study, the OEFs were calculated as a function of the plant capacity, and expressed in ou_Et⁻¹, because of the existence of a proportionality between plant capacity and odour emissions. The results show that the major odour source of a waste MBT plant is represented by the aerobic biological treatment (with an OEF equal to 1.40×10⁸ou_Et⁻¹). In general, the OEFs calculated according to this approach represent a model for a rough prediction of odour emissions independently from the specific characteristics of the different plants.

Keywords: Mechanical biological treatment; Composting; Specific odour emission rate; Odour emission factors; Odour prediction

Quantifying the ozone “weekend effect�? at various locations in Phoenix, Arizona by Carol M. Atkinson-Palombo; James A. Miller; Robert C. Balling Jr. (pp. 7644-7658).

Analysis of pollution data from a network of monitors in Maricopa County, Arizona, reveals considerable variation in the magnitude of the ozone “weekend effect�? depending on how and where it is measured. We used four separate methods to calculate the weekend effect, all of which showed that the phenomenon is stronger in the urban core, where ozone is produced. Spatial linear regressions show that the magnitude of the weekend effect and the goodness of fit of weekly harmonic cycles in ozone is a function of urbanization, described quantitatively using an index of traffic counts, population, and employment within a 4km buffer zone of monitoring sites. Analysis of diurnal patterns of ozone as well as oxides of nitrogen (NO _x) at a representative site in the urban core supports the hypothesis that lower levels of NO _x on Sundays reduce the degree to which ozone is titrated, resulting in a higher minimum and hence mean for that day of the week (DOW). Fringe sites, where ozone concentrations are higher in absolute terms than in the urban core, show almost no “weekend effect,�? regardless of which of the four individual methods we used. Alternative quantification methods show statistically significant DOW differences in ozone levels in urban fringe locations, albeit out of phase with the weekly cycling of ozone in the urban core. Our findings suggest that multiple metrics need to be used to test for the weekend effect and that the causes of DOW differences in ozone concentrations may be location specific.

Keywords: Atmospheric pollution; Ozone precursors; Weekend/weekday effects; Temporal variation; Harmonic analysis

Erratum to “Continuous weeklong measurements of personal exposures and indoor concentrations of fine particles for 37 health-impaired North Carolina residents for up to four seasons�? by Lance Wallace; Ron Williams; Anne Rea; Carry Groghan (pp. 7659-7660).

Corrigendum to “Source apportionment of PM2.5 in Beijing by positive matrix factorization�? by Yu Song; Yuanhang Zhang; Shaodong Xie; Limin Zeng; Mei Zheng; Lynn G. Salmon; Min Shao; Sjaak Slanina (pp. 7661-7662).

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Atmospheric Environment (v.40, #39)