Publications (28)31.2 Total impact
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Article: Emissoes de queimadas em ecossistemas da America do Sul
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ABSTRACT: The vegetation fires in tropical arcas of the Earth are important sources of pollutants to the atmosphere. In South America, during the winter months, an area, mainly of cerrado and forest ecosystems, of approximately 40 thousand square kilometers is burned annually. The biomass burning occurs primarily in Amazon and Central of Brazil regions, but through atmospheric transport these emissions results in a spatial distribution of smoke over an extent arca, of about 4-5 millions of square kilometers, much higher than the arca where the fires are concentrated. During the combustion process are emitted to the atmosphere gases pollutants and aerosol particles that interact efficiendy with radiation, microphysics process, dynamic of cloud formation and the air quality. The effects of these emissions exceed, therefore, the local scale and affect regionally the composition and physical and chemical properties of the South America atmosphere and neighborhood oceanic arcas, with potential impact in a global scale. Resumo: As queimadas que ocorrem majoritariamente em áreas tropicais do planeta, são fontes importantes de poluentes para a atmosfera. Na América do Sul, durante os meses de inverno, uma área, principalmente de ecossistemas de cerrado e floresta, da ordem de 40 mil km2 é queimada anualmente. Estas queimadas ocorrem primariamente nas regiões Amazônica e do Brasil Central, porém, através do transporte atmosférico de suas emissões resulta uma distribuição espacial de fumaça sobre uma extensa área, ao redor de 4-5 milhões de km2, em muito superior a área onde estão concentradas as queimadas. Durante a combustão de biomassa são emitidos para a atmosfera gases poluentes e partículas de aerossol que interagem eficientemente com a radiação solar e afetam os processos de microfísica e dinâmica de formação de nuvens e a qualidade do ar. Os efeitos destas emissões excedem, portanto, a escala local e afetam regionalmente a composição e propriedades físicas e químicas da atmosfera na América do Sul e áreas oceânicas vizinhas, com potencial impacto em escala global. Pages: 167-18501/2005; -
Article: Smoking Rain Clouds over the Amazon
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ABSTRACT: Heavy smoke from forest fires in the Amazon was observed to reduce cloud droplet size and so delay the onset of precipitation from 1.5 kilometers above cloud base in pristine clouds to more than 5 kilometers in polluted clouds and more than 7 kilometers in pyro-clouds. Suppression of low-level rainout and aerosol washout allows transport of water and smoke to upper levels, where the clouds appear "smoking" as they detrain much of the pollution. Elevating the onset of precipitation allows invigoration of the updrafts, causing intense thunderstorms, large hail, and greater likelihood for overshooting cloud tops into the stratosphere. There, detrained pollutants and water vapor would have profound radiative impacts on the climate system. The invigorated storms release the latent heat higher in the atmosphere. This should substantially affect the regional and global circulation systems. Together, these processes affect the water cycle, the pollution burden of the atmosphere, and the dynamics of atmospheric circulation. Pages: 1337-1342Science 03/2004; · 31.20 Impact Factor -
Article: Nitrogen oxides measurements in an Amazon site and enhancements associated with a cold front
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ABSTRACT: An intensive atmospheric chemistry study was carried out in a pristine Amazonian forest site (Balbina), Amazonas state, Brazil during the 2001 wet season, as part of the LBA/CLAIRE 2001 (The Large Scale Biosphere Atmosphere Experiment in Amazonia/Cooperative LBA Airborne Regional Experiment) field campaign. Measurements of nitrogen oxide (NO), nitrogen dioxide (NO2) and ozone (O3) were performed simultaneously with aerosol particles and black carbon concentrations and meteorological parameters observations. Very low trace gases and aerosol concentrations are typically observed at this pristine tropical site. During the measurement period, there was a three-day episode of enhancement of NO2 and black carbon concentration. NO2 concentration reached a maximum value of 4 ppbv, which corresponds to three times the background concentration observed for this site. Black carbon concentration increased from the approximated 100 ng/m3 average value to a 200 ng/m3 maximum during the same period. Biomass burning spots were detected southward, between latitudes 15 to 10° S, 56 days before this episode from GOES-8 WF_ABBA (Wildfire Automated Biomass Burning Algorithm). An atmospheric numerical simulation of the whole measurement period was carried out using the RAMS model coupled to a biomass burning emission and transport model. The simulation results pictured a smoke transport event from Central Brazil associated to an approach of a mid-latitude cold front, reinforcing the hypothesis of biomass burning products being long-range transported from the South by the cold front and crossing the Equator. This transport event shows how the pristine atmosphere pattern in Amazonia is impacted by biomass burning emissions from sites very far away.. Pages: 2301-233101/2004; -
Article: Can the slowing of auto-conversion result in increasing precipitation?
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ABSTRACT: Pages: 30-33 -
Article: Monitoring the transport of biomass burning emissions in South America
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ABSTRACT: The atmospheric transport of biomass buming emissions in the South American and African continents is being monitored annually using a numerical simulation of air mass motions; we use a tracer transport capability developed within RAMS (Regional Atmospheric Modeling Sys- tem) coupled to an emission modelo Mass conservation equations are solved for carbon monoxide (CO) and particulate material (PM2.5). Source emissions of trace gases and particles associated with biomass buming activities in tropical forest, savanna and pasture have been parameterized and introduced into the modelo The sources are distributed spatially and temporally and assimilated daily using the biomass buming locations detected by remote sensing. Advection effects (at grid scale) and turbulent transport (at sub-grid scale) are provided by the RAMS parameterizations. A sub- grid transport parameterization associated with moist deep and shallow convection, not explicitly resolved by lhe modeldue to its low spatial resolution, has also been introduced. Sinks associated with lhe process of wet and dry removal of aerosol particles and chemical transformation of gases are parameterized and introduced in lhe mass conservation equation. An operational system has been implemented which produces daily 48-h numerical simulations (including 24-h forecasts) of CO and PM2.5, in addition to traditional meteorological fields. The good prediction skills of lhe model are demonstrated by comparisons with time series of PM2.5 measured at the surface. Pages: 135 - 167 -
Article: The Interaction of Clouds and Rain with the Biosphere
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ABSTRACT: In January and February of 1999 LBA launched its first Wet Season Atmospheric Mesoscale Campaign (WETAMC), organized jointly with the Tropical Rainfall Measuring Mission - TRMM - validation campaign (known as TRMM/LBA). Both campaigns took place in Rondônia, Brazils southwest Amazon (see Figure 1 for map of observation sites). Preliminary results indicate a picture of an intrinsically coupled rain producing system where different processes interact at different space and time scales and where the underlying surface, either forest or deforested, actively participates in several mechanisms of cloud formation. Pages: 8-11 -
Article: Airborne measurements of trace gas and aerosol particle emission from biomass burning in Amazonia
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ABSTRACT: As part of the LBA-SMOCC(Large-Scale Biosphere-Atmosphere Experiment in Amazonia-Smoke, Aerosols, Clouds, Rainfall, and Climate) 2002 campaingn, we studied the emission of carbon monoxide (CO), carbon dioxide (CO2), and aerosol particles from Amazonian deforestation fires using an instrumented aircraft, Emission ratios for aerosol number (CN) relative to CO (ERcn/co) fell in the range for most of the time, in agreement with values usually found from tropical savanna fires. The number of particles emitted per amount biomass burned was found to be dependant on the fire condition (combustion efficiency). Variability in the ERcn/co between fires was similar to the variability caused by variations in combustion behavior within each individual fire.Vertical transport of biomass-burning plumes from the boundary layer (BL) to the cloud detrainment layer (CDL) and the free troposphere (FT) was found to be a very common phenomenon. This small loss fraction sugggests that this mode of transport is very efficient in terms of particle released in the CDL and FT were larger due to coagulation. This smallloss fraction suggests cloud processing, atributable to in-cloud coagulation. This process may have significant may have significant atmospheric implications on a regional and larger scale. Pages: 2791-2831 -
Article: LBA-SMOCC: observations of interactions between aerosols and cloud microphysics over the Amazon
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Article: Aerosols impact clouds in the Amzon Basin
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ABSTRACT: Most of the Amazon Basin has marked yearly cycle of rainfall with a short dry season, a long and shorttransitions between the dry and the wet seasons. In the dry seasonn and in the transition to the dry season, biomass burning takes place mainly at the southern and eastern sectors of the Amazon Basin and provides a ten-fold increase in the background number concentration of aerosols and cloud condensation nuclei. In the wet season, the main source of aerosols and fine mode particles from the gas-to-particle conversion from volatile organic compounds emissions. The main sources of aerosol particles in the coarse mode in Amazonia are soil dust and natural primary biogenic particles, where in the fine mode, secondary organic biogenic particles and biomass burning smoke predominate. Pages: 4-5 -
Article: Cloud and rain processes in a biosphere-atmosphere interaction context in the Amazon Region
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ABSTRACT: This paper presents an overview of the results from the first major mesoscale atmospheric campaign of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) Program. The campaign, collocated with a Tropical Rainfall Measuring Mission (TRMM) satellite validation campaigns, was conducted in southwest Rondonia in January and February 1999 during the wet season. Highlights on the interaction between clouds, rain, and the underlying landscape through biospheric processes are presented and discussed. Pages: art. no. 8072 -
Article: General aspects of the rebio-jaru Amazon forest micrometeorological tower LBA wet season campaign and preliminary results
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ABSTRACT: A description of the 60m height micrometeorological tower built at the Amazonian Forest Rebio-Jaru Reserve (10 04' S; 61 56' W) during the LBA (Large Scale Biosphere Atmosphere Experiment in Amazonia) wet season campaign (January to March 1999), in the Brazilian State of Rondonia, is presented. Also, some of the preliminary results obtained during the campaign are presented. The Amazonian forest canopy has a mean height of 35m; however, some of the higher tree branches have heights up to 45m. So, to start the turbulent exchange process studies in this site, it is important to admit that there is a thermodynamic canopy height of about 35m, and another aerodynamic of about 45m. These facts were considered to decide the appropriate height at which the instruments were placed on the tower. Fast response instruments (3D sonic-anemometers, thermometers and hygrometers), with a sampling rate of 16 Hz (except during three days, when the sampling rate was 60Hz), were installed. Also, slow response instruments, operated at a sampling rate of 0.1Hz, provided vertical profiles of the following meteorological variables: wind velocity, temperature, specific humidity, incoming solar radiation, net radiation and photosynthetically active radiation (PAR). One of the goals of this investigation was to analyse the dependence of the vertical eddy fluxes on the cutoff time scale, as well as on the flux averaging time scale. In this sense, graphs of composite averaged fluxes and their changes with increasing cutoff scale, for several hours in a typical convective day in Amazonia are presented. They are similar to the ones presented by Sun et al (1). The results show that the flux averaging scale needed to stabilize the flux calculation changes along the day, and reaches a value greater than 20min around noon time. Some typical patterns of the diurnal variability of the measured micrometeorological variables above and inside the forest canopy are also presented. These results explain some of the physical aspects of the time variability patterns in the Amazonian Forest on a wet day. -
Article: Dry to wet season LBA campaign in the Amazon radiation, clouds and climate interactions
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ABSTRACT: During the Iransilion fromthe dry to wet season in 2002 (Seplember and October). an atmospheric intensive field campaign was carried in the southwestern region of the Amazon Basin within the framework of. The Large Scale Biosphere Atmosphere Experiment in Amazonia -LBA. The specific objectives of the DRYTOWET/LBA campaign were 10 describe and analyze: the global and large scale conb"ols of the beginning of the rainy season in the Amazon Region; the impact of convection in the Amazon region on the global and regional clímate in the transition season; the transition season in terms of cloud patlem evolution and aerosol concentration; the weather systems and air mass evolution during the transitíon from the dry to wet season; the several convective features of the Ar1:1azon region in lhe transition season including fite cycle. rainfall intensíly, líghtning. dynamics and thermodynamics; the relationship between CCN and convective patterns; the temperature inversíon equilibrium ín the presence of a mixed I.ayer wilh aerosol and its evolution afterthe first major rains; the evolution of the PBL during the transition season as a function of soil moísture and of evapotranspiration; the surface and PBL radíatíve budgel before, during and after the beginning of the rainy season. over forest and over pasture; the impact of land cover heterogeneity on PBL and surface layer turbulence during the transition season; the evolution of surface energy. momentum. water and CO2 budgets in pasture and forest and íts seasonal and interannual variabílity; the radíative transfer processes in the presence of aerosol and to what extent they modify the processes associated to water vapor seasonality; the microphysics processes with different aerosol concentration and to improve the ability to model the different processes in an integrated view of clímate and regional weather. -
Article: The convective boundary layer over pasture and forest in Amazonia
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ABSTRACT: The coupling between different types of surface (tropical forest or grass) and the Convective Boundary Layer (CBL) has been investigated using observational (rawinsoundings) data collected over Rondônia in southwest Amazonia. The data reported here support the notion that deforestation may modify the dynamics of the boundary layer, in particular during the dry season. In this period the sensible heat fluxes are very high over pasture, creating a CBL around 550m deeper compared to that over the forest. The measurements showed the height of the fully developed CBL for pasture to be 1650m, compared to around 1100m for forest. During the wet season the height of the CBL is lower than during the dry season and has the same height (around 1000m) for forest and pasture sites. The CBL over pasture is hotter and drier than over forest during the dry season, but during the wet season the air temperatures and humidities are similar. Comparing the CBL growth during the dry and wet season, there is evidence that the CBL properties over the forest are not dependent on the surface characteristics, but over the pasture they are. Pages: 47-59 -
Article: Monitoring the transport of biomass burning emissions in South America
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ABSTRACT: The atmospheric transport of biomass burning emissions in the South American and African continents is monitored with the aid of numerical simulation of air mass motions using the tracer transport capability of the atmospheric model RAMS (Regional Atmospheric Modeling System) coupled to an emission model. In this application, the mass conservation equation is solved for carbon monoxide (CO) and particulate material (PM2.5). Source emissions of trace gases and particles associated with biomass burning activities in tropical forest, savanna and pasture are parameterized and introduced into the model. The sources are distributed spatially and temporally and assimilated daily according to the biomass burning locations detected by remote sensing. Advection at grid scale, and turbulent transport at sub-grid scale, are provided by the RAMS parameterizations. A sub-grid transport parameterization associated with moist deep and shallow convection, not explicitly resolved by the model due to its low spatial resolution, is also introduced. Sinks associated with wet and dry removal of aerosol particles and chemical transformation of gases are parameterized and introduced into the mass conservation equation. An operational system was implemented producing daily 48-hour numerical simulations (24-hour forecast) of the mass concentrations for CO and PM2.5, in addition to traditional meteorological fields. Time series of PM2.5 measured at the surface are compared with the model results and demonstrate the good forecasting ability of the model. -
Article: The convective boundary layer over pasture in Amazonia during the LBA Dry-to-Wet Experiment 2002
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ABSTRACT: The coupling between a typical ranchland and the Convective Boundary Layer (CBL) has been investigated using radiosoundings at 8, 11, 14 and 17 Local Time (- 4 hours from GMT), as a part of LBA/DRY-TO-WET 2002 experiment. The field campaign held from Sept 15 up to Oct 30, 2002, extending from the end of the dry season (Sept) to the onset of the wet period (Oct). The profiles of potential temperature and specific humidity have been used to compute the mean properties of the CBL, as well as the height of the CBL. The CBL height varied from a typical value around 2000-2200 m during the end of the dry season (Sept 18-20,2002) to a figure around 1600-1800 m in the beginning of the wet period (20-28,Oct). The potential temperature and humidity profiles did not changed remarkable during this period, oscillating from 307 - 308 K and 12 - 14 g/kg. During the beginning of the wet season, some local showers have occurred and produced a remarkable change in the structure of the CBL. Some events have been analyzed. For instance, on Sept 28,2002, the height of the CBL was around 1400-1500 m at 14 LT with a average potential temperature (q) around 306 K and specific humidity (q) of 13.5 g/kg. After a very strong rainfall (38 mm/3 hours) at afternoon, the CBL has been destroyed (height around 500 m) with q of 300 K and q around 15-16 g/kg. There was also a nocturnal jet case (night from Sept 23-24) with strong wind of 11 m/s at 500 m. This strong windshear created an unexpected shallow mixed layer (height of 400 m) during the night instead of the nocturnal/stable pattern. This data-set will provide opportunity for modeling studies of the growing of the CBL and coupling with aerosols and/or clouds. -
Article: Smoke Aerosols, Clouds, Rain and Climate
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ABSTRACT: Research over the past decade has confirmed and highlighted the importance of a number of aerosol effects on climate, both through direct interaction of the aerosol with solar and terrestrial radiation, and via perturbations of cloud properties and convective dynamics. In this presentation, I will highlight recent results from a study of the effect of biomass smoke on tropical clouds and the consequences for regional and global climate. We investigated the emission of smoke from biomass burning, its regional distribution, and its effects on cloud microphysics during the LBA-SMOCC experiment in Amazonia, September-October 2002. The campaign consisted of airborne, ground-based, remote-sensing, and modeling components. Two instrumented aircraft investigated trace gases, aerosol properties and cloud microphysics across a large region that comprised highly polluted and essentially pristine airmasses. At a ground site, we made continuous measurements of trace gases and a large suite of aerosol properties, and collected samples for laboratory analysis. Measurements spanned from the peak of the burning season, with high smoke concentrations, to fairly clean conditions in the early rainy season. We found high loadings of smoke particles and pyrogenic trace gases in the boundary layer over vast reaches of Amazonia, and evidence for efficient vertical transport of smoke into the free troposphere. Smoke aerosols had pronounced effects on the radiation budget, cloud microphysics and precipitation formation over Amazonia, as show by in-situ measurements and remote sensing data. These effects are likely to perturb convective dynamics, radiative flux, and atmospheric composition on regional to global scales. -
Article: Detection of real time influence regions on the eddy flux and concentration measurements as a support for aircraft measurements during FIRE
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ABSTRACT: This work describes a methodology which determines the most significant regions to have measures token with instrumented aircrafts. This methodology is based on the influence functions theory, and will be used during the FIRE campaign, which will take place in the end of 2004 dry season in Mato Grosso area. At the first stage, high-resolution numeric weather forecasts will be run with BRAMS model. Before the campaign, the mean squared error (MSE) between the forecasts and the radiosonde measurements of wind velocity will be estimated. From these forecasts, considering the error, the STILT lagrangean model, which allows the time-inverted integration, will be applied. STILT will be run from the 72-hour forecast at fixed points chosen from the concentration and flux measurement sites. This model outputs a trajectory plume as well as influence functions. Preliminary sensitivity tests have been developed in order to verify how adequate this framework is to the FIRE region. A simulation over Mato Grosso in October 15th to 17th, 2002 will be presented. During this period, widespread convection was observed over the focused area. Results show that the air particles behaviour within the mixing layer and the vertical displacement due to the convective activity are well reproduced. When the MSE is considered, the influence function field becomes suggests a larger area, which is desirable when the flight over significant regions is planned. -
Article: Perfis de aquecimento diabatico na Regiao Amazonica
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ABSTRACT: A liberação de calor latente associada à intensa precipitação que ocorre nas regiões tropicais é um importante fator na determinação das características das circulações atmosféricas em diversas escalas espaciais e temporais. Este trabalho tem como objetivo realizar uma comparação da estrutura vertical do aquecimento diabático em diferentes regiões da Floresta Amazônica. O aquecimento foi calculado como resíduo da equação da termodinâmica. Os dados utilizados são da re-análise do NCEP, para os meses de janeiro e fevereiro de 1994 a 2004. Foram feitas também análises para períodos com diferentes regimes de vento. O nível de máximo aquecimento diabático está associado à situação que o gerou. Em uma região com pouca convecção, a superfície funciona como fonte de calor sensível e os máximos se localizam nos níveis mais baixos da troposfera, invertendo-se a noite, quando a superfície torna-se mais fria. Já uma fonte localizada em níveis mais altos está associada à liberação de calor latente podendo estar associada à convecção rasa ou profunda, dependendo dos níveis de máximo aquecimento. De uma forma geral, as regiões no Hemisfério Norte apresentam um perfil de atmosfera seca, enquanto as do Hemisfério Sul, em sua maioria, apresentam maior liberaçaõ de calor latente em níveis mais altos. -
Article: Microphysical evidence of the transition between predominant convective/stratiform rainfall associated to the large-scale variability of precipitation in Southwest Amazon
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ABSTRACT: The distinction between convective and stratiform precipitation profiles around various precipitating systems existent in tropical regions is very important to the global atmospheric circulation, which is extremely sensitive to vertical latent heating distribution. In South America, the convective activity responds to the Intraseasonal Oscillation (OIS). This work analyzes data from a disdrometer, a radar profiler and a polarimetric radar, installed in the Ji-Paraná airport, RO, Brazil, for the field experiment WETAMC/LBA & TRMM/LBA, in January and February of 1999. The methodology is based on the partion of the precipitation into convective and stratiform, and the classification of hydometeors by fuzzy logic systems. The microphysical analysis of the periods with the presence or the absence of the South Atlantic Convergence Zone (ZCAS), associated to the IOS, showed a large difference in type, size and microphysical processes of hydrometeor growth in each wind regime: periods without a ZCAS presented more intense convection, leading strong processes of the precipitation growth in both convective and stratiform types; during periods with a well stabilished ZCAS, there were small precipitating systems, with a less convective feature, similary to those from monsoon regions in their ative phase. -
Article: Numerical modelling of the biomass-burning aerosol direct radiative effects on the thermodynamic structure of the atmosphere and convective precipitation
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ABSTRACT: The atmospheric transport of biomass burning emissions in South America and the direct radiative effects of the aerosol particles of the regional haze are addressed in this work. This study is carried out through a numerical simulation of the atmospheric motions using the Coupled Aerosol Tracer Transport to the Brazilian Regional Atmospheric Modeling System CATT-BRAMS. A radiative code that includes the aerosol particle absorption and scattering is fully coupled to the CATT-BRAMS allowing atmospheric model feedback studies. The atmospheric model responds to the presence in the atmosphere of this highly absorber aerosol particles, from the direct radiative point of view, cooling the atmosphere in the lower levels and heating it in the upper levels of the boundary layer. Temperature gradients associated with the presence of the biomass-burning aerosol can reach 2 Celcius degrees over very polluted areas. Consequently, the atmospheric model responds with a reduction of the kinetic turbulent energy, stabilizing the atmosphere and suppressing the convective precipitation.
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- Science (1)
Institutions
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2004
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Universidade de São Paulo
- Instituto de Física (IF) (São Paulo)
São Paulo, Estado de Sao Paulo, Brazil -
Max Planck Institute for Chemistry
München, Bavaria, Germany
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