Maryland Shared Open Access Repository
MD-SOAR is a shared digital repository platform for twelve colleges and universities in Maryland. It is currently funded by the University System of Maryland and Affiliated Institutions (USMAI) Library Consortium (usmai.org) and other participating partner institutions. MD-SOAR is jointly governed by all participating libraries, who have agreed to share policies and practices that are necessary and appropriate for the shared platform. Within this broad framework, each library provides customized repository services and collections that meet local institutional needs. Please follow the links below to learn more about each library's repository services and collections.
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Urban influence on the concentration and composition of submicron particulate matter in central Amazonia
(EGU, 2018-08-23) de Sá, Suzane S.; Palm, Brett B.; Campuzano-Jost, Pedro; Day, Douglas A.; Hu, Weiwei; Isaacman-VanWertz, Gabriel; Yee, Lindsay D.; Brito, Joel; Carbone, Samara; Ribeiro, Igor O.; Cirino, Glauber G.; Liu, Yingjun; Thalman, Ryan; Sedlacek, Arthur; Funk, Aaron; Schumacher, Courtney; Shilling, John E.; Schneider, Johannes; Artaxo, Paulo; Goldstein, Allen H.; Souza, Rodrigo A. F.; Wang, Jian; McKinney, Karena A.; Barbosa, H. M. J.; Alexander, M. Lizabeth; Jimenez, Jose L.; Martin, Scot T.
An understanding of how anthropogenic emissions affect the concentrations and composition of airborne particulate matter (PM) is fundamental to quantifying the influence of human activities on climate and air quality. The central Amazon Basin, especially around the city of Manaus, Brazil, has experienced rapid changes in the past decades due to ongoing urbanization. Herein, changes in the concentration and composition of submicron PM due to pollution downwind of the Manaus metropolitan region are reported as part of the GoAmazon2014/5 experiment. A high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a suite of other gas- and particle-phase instruments were deployed at the “T3” research site, 70 km downwind of Manaus, during the wet season. At this site, organic components represented 79±7 % of the non-refractory PM1 mass concentration on average, which was in the same range as several upwind sites. However, the organic PM1 was considerably more oxidized at T3 compared to upwind measurements. Positive-matrix factorization (PMF) was applied to the time series of organic mass spectra collected at the T3 site, yielding three factors representing secondary processes (73±15 % of total organic mass concentration) and three factors representing primary anthropogenic emissions (27±15 %). Fuzzy c-means clustering (FCM) was applied to the afternoon time series of concentrations of NOy, ozone, total particle number, black carbon, and sulfate. Four clusters were identified and characterized by distinct air mass origins and particle compositions. Two clusters, Bkgd-1 and Bkgd-2, were associated with background conditions. Bkgd-1 appeared to represent near-field atmospheric PM production and oxidation of a day or less. Bkgd-2 appeared to represent material transported and oxidized for two or more days, often with out-of-basin contributions. Two other clusters, Pol-1 and Pol-2, represented the Manaus influence, one apparently associated with the northern region of Manaus and the other with the southern region of the city. A composite of the PMF and FCM analyses provided insights into the anthropogenic effects on PM concentration and composition. The increase in mass concentration of submicron PM ranged from 25 % to 200 % under polluted compared with background conditions, including contributions from both primary and secondary PM. Furthermore, a comparison of PMF factor loadings for different clusters suggested a shift in the pathways of PM production under polluted conditions. Nitrogen oxides may have played a critical role in these shifts. Increased concentrations of nitrogen oxides can shift pathways of PM production from HO2-dominant to NO-dominant as well as increase the concentrations of oxidants in the atmosphere. Consequently, the oxidation of biogenic and anthropogenic precursor gases as well as the oxidative processing of preexisting atmospheric PM can be accelerated. This combined set of results demonstrates the susceptibility of atmospheric chemistry, air quality, and associated climate forcing to anthropogenic perturbations over tropical forests.
Observations of Manaus urban plume evolution and interaction with biogenic emissions in GoAmazon 2014/5
(Elsevier, 2018-08-25) Cirino, Glauber; Brito, Joel; Barbosa, H. M. J.; Rizzo, Luciana V.; Tunved, Peter; de Sá, Suzane S.; Jimenez, Jose L.; Palm, Brett B.; Carbone, Samara; Lavric, Jost V.; Souza, Rodrigo A. F.; Wolff, Stefan; Walter, David; Tota, Júlio; Oliveira, Maria B. L.; Martin, Scot T.; Artaxo, Paulo
As part of the Observations and Modeling of the Green Ocean Amazon (GoAmazon 2014/5) Experiment, detailed aerosol and trace gas measurements were conducted near Manaus, a metropolis located in the central Amazon Basin. Measurements of aerosol particles and trace gases were done downwind Manaus at the sites T2 (Tiwa Hotel) and T3 (Manacapuru), at a distance of 8 and 70?km from Manaus, respectively. Based on in-plume measurements closer to Manaus (site T2), the chemical signatures of city emissions were used to improve the interpretation of pollutant levels at the T3 site. We derived chemical and physical properties for the city's atmospheric emission ensemble, taking into account only air masses impacted by the Manaus plume at both sites, during the wet and dry season Intensive Operating Periods (IOPs). At T2, average concentrations of aerosol number (CN), CO and SO2 were 5500?cm?3 (between 10 and 490?nm), 145?ppb and 0.60?ppb, respectively, with a typical ratio ?CN/?CO of 60–130 particles cm?3?ppb?1. The aerosol scattering (at RH?
Aerosol optical depth retrievals in central Amazonia from a multi-filter rotating shadow-band radiometer calibrated on-site
(EGU, 2019-02-11) Rosário, Nilton E.; Sauini, Thamara; Pauliquevis, Theotonio; Barbosa, H. M. J.; Yamasoe, Marcia A.; Barja, Boris
Extraterrestrial spectral response calibration of a multi-filter rotating shadow band radiometer (MFRSR) under pristine Amazonian Forest atmosphere conditions was performed using the Langley plot method. The MFRSR is installed in central Amazonia as part of a long-term monitoring site, which was used in the context of the GoAmazon2014/5 experiment. It has been operating continuously since 2011 without regular extraterrestrial calibration, preventing its application to accurate monitoring of aerosol particles. Once calibrated, the MFRSR measurements were applied to retrieve aerosol particle columnar optical properties, specifically aerosol optical depth (AOD?) and Ångström exponent (AE), which were evaluated against retrievals from a collocated Cimel Sun photometer belonging to the AErosol RObotic NETwork (AERONET). Results obtained revealed that pristine Amazonian conditions are able to provide MFRSR extraterrestrial spectral response with relative uncertainty lower than 1.0 % in visible channels. The worst estimate (air mass =1) for absolute uncertainty in AOD? retrieval varied from ?0.02 to ?0.03, depending on the assumption regarding uncertainty for MFRSR direct normal irradiance measured at the surface. The obtained root mean square error (RMSE ?0.025) from the evaluation of MFRSR retrievals against AERONET AOD? was, in general, lower than estimated MFRSR AOD? uncertainty, and close to the uncertainty of AERONET field Sun photometers (?0.02).
Extracting first science measurements from the southern detector of the Pierre Auger observatory
(ELSEVIER, 2007-03-01) Wiencke, L.; Pierre Auger Collaboration; Barbosa, H. M. J.
The world's largest cosmic-ray detector is nearing completion in the remote Pampas of Argentina. This instrument measures extensive air-showers with energies from 1018 to 1020eV and beyond. A surface detector array of area 3000km2 records the lateral distribution of charged particles at ground level. A fluorescence detector overlooking the surface detector records the longitudinal light profiles of showers in the atmosphere to make a calorimetric energy measurement. A “test beam” for the fluorescence detector is generated by a calibrated laser near the array center. This talk will focus on detector characterizations essential to the first science results that have been reported from the observatory. Plans to construct a larger instrument in the northern hemisphere will also be outlined.
Urban pollution greatly enhances formation of natural aerosols over the Amazon rainforest
(Nature, 2019-03-05) Shrivastava, Manish; Andreae, Meinrat O.; Artaxo, Paulo; Barbosa, H. M. J.; Berg, Larry K.; Brito, Joel; Ching, Joseph; Easter, Richard C.; Fan, Jiwen; Fast, Jerome D.; Feng, Zhe; Fuentes, Jose D.; Glasius, Marianne; Goldstein, Allen H.; Alves, Eliane Gomes; Gomes, Helber; Gu, Dasa; Guenther, Alex; Jathar, Shantanu H.; Kim, Saewung; Liu, Ying; Lou, Sijia; Martin, Scot T.; McNeill, V. Faye; Medeiros, Adan; de Sá, Suzane S.; Shilling, John E.; Springston, Stephen R.; Souza, R. a F.; Thornton, Joel A.; Isaacman-VanWertz, Gabriel; Yee, Lindsay D.; Ynoue, Rita; Zaveri, Rahul A.; Zelenyuk, Alla; Zhao, Chun
One of the least understood aspects in atmospheric chemistry is how urban emissions influence the formation of natural organic aerosols, which affect Earth’s energy budget. The Amazon rainforest, during its wet season, is one of the few remaining places on Earth where atmospheric chemistry transitions between preindustrial and urban-influenced conditions. Here, we integrate insights from several laboratory measurements and simulate the formation of secondary organic aerosols (SOA) in the Amazon using a high-resolution chemical transport model. Simulations show that emissions of nitrogen-oxides from Manaus, a city of ~2 million people, greatly enhance production of biogenic SOA by 60–200% on average with peak enhancements of 400%, through the increased oxidation of gas-phase organic carbon emitted by the forests. Simulated enhancements agree with aircraft measurements, and are much larger than those reported over other locations. The implication is that increasing anthropogenic emissions in the future might substantially enhance biogenic SOA in pristine locations like the Amazon.