GREGORI DE ARRUDA MOREIRA

GREGORI DE ARRUDA MOREIRA

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Pollutant levels in São Paulo’s Metropolitan Region and the SARS-CoV-2 pandemic
2024 - MOREIRA, GREGORI de A.; CACHEFFO, ALEXANDRE; ANDRADE, IZABEL da S.; LOPES, FABIO J. da S.; GOMES, ANTONIO A.; LANDULFO, EDUARDO
In this work, we demonstrate how the variation in vehicular traffic due to the SARS-CoV-2 pandemic and the resumption of activities affected the concentrations of some pollutants (CO, NO2, PM2.5, andvPM10) in the Metropolitan Region of São Paulo. For this purpose, we estimate the convective boundary layer (CBL) height from lidar measurements and radiosonde retrievals and calculate the ventilation coefficient, an essential parameter to evaluate the air pollutants’ dispersion level. In addition, it was observed the variation of some meteorological variables (air surface temperature, humidity, and rainfall rate) to identify the occurrence of conditions that can favor pollutant dispersion. Finally, based on the time series of the pollutants previously mentioned, we created an Artificial Neural Network (ANN) to identify what will be the concentration of thesepollutants in normal conditions (no pandemic period). The results demonstrated that during the pandemic period, there was no significant change in the meteorological variables studied. However, there was a significant reduction in the concentration of pollutants whose main source is vehicular traffic (CO and NO2) and a significant increase with the resumption of activities, with the pre-pandemic level having already been reached within a few weeks. The findings here shown indicate that integrating remote sensing tools, surface data, and artificial intelligence techniques significantly enhances understanding of pollutant dynamics. Properly trained ANN algorithms offer the potential for applying this methodology in other regions.
Analyzing the influence of the planetary boundary layer height, ventilation coefficient, thermal inversions, and aerosol optical Depth on the concentration of PM2.5 in the city of São Paulo
2024 - MOREIRA, GREGORI de A.; MARQUES, MARCIA T.A.; LOPES, FABIO J. da S.; ANDRADE, MARIA de F.; LANDULFO, EDUARDO
Cases of intense air pollution have been a recurring problem in most of urban centers in different regions of the world. Although actions to mitigate pollutant emissions are fundamental, it is also necessary to understand which factors can favor their dispersion process. In this scenario, this paper presents, for the first time, a long-term analysis of the Planetary Boundary Layer Height (PBLH), estimated through lidar and radiosounding data, Ventilation Coefficient (VC), Thermal Inversions (TI), and Aerosol Optical Depth (AOD), for the city of São Paulo, demonstrating how these variables are related with PM2.5 concentration. The analyzes showed that PBLH and VC have a seasonal cycle, with higher values in summer and lower ones in winter. Furthermore, PBLH is affected by one local factor, the sea-breeze, which reduces the concentration of aerosols in the late afternoon, resulting in an underestimated PBLH obtained from lidar data. Furthermore, from AERONET data, a predominance of Black Carbon and small particles was observed in all seasons, which are associated with the feedback effect observed in winter. Such effect attenuates the increase of PBLH and VC in cases of high concentrations of PM2.5. Finally, it was presented a Generalized Linear Model, which combines VC, AOD and TI information as input and can estimate the PM2.5 concentration with a R2 = 0.93.
Impact of extreme wildfires from the Brazilian Forests and sugarcane burning on the air quality of the biggest megacity on South America
2023 - SOUTO-OLIVEIRA, CARLOS E.; MARQUES, MARCIA T.A.; NOGUEIRA, THIAGO; LOPES, FABIO J.S.; MEDEIROS, JOSE A.G.; MEDEIROS, ILCA M.M.A.; MOREIRA, GREGORI A.; DIAS, PEDRO L. da S.; LANDULFO, EDUARDO; ANDRADE, MARIA de F.
Recently, extreme wildfires have damaged important ecosystems worldwide and have affected urban areas miles away due to long-range transport of smoke plumes. We performed a comprehensive analysis to clarify how smoke plumes from Pantanal and Amazon forests wildfires and sugarcane harvest burning also from interior of the state of São Paulo (ISSP) were transported and injected into the atmosphere of the Metropolitan Area of São Paulo (MASP), where they worsened air quality and increased greenhouse gas (GHG) levels. To classify event days, multiple biomass burning fingerprints as carbon isotopes, Lidar ratio and specific compounds ratios were combined with back trajectories modeling. During smoke plume event days in the MASP fine particulate matter concentrations exceeded the WHO standard (>25 μg m−3 ), at 99 % of the air quality monitoring stations, and peak CO2 excess were 100 % to 1178 % higher than non-event days. We demonstrated how external pollution events such as wildfires pose an additional challenge for cities, regarding public health threats associated to air quality, and reinforces the importance of GHG monitoring networks to track local and remote GHG emissions and sources in urban areas.
Analyzing the influence of vehicular traffic on the concentration of pollutants in the city of São Paulo
2023 - MOREIRA, GREGORI de A.; CACHEFFO, ALEXANDRE; ANDRADE, IZABEL da S.; LOPES, FABIO JULIANO da S.; GOMES, ANTONIO A.; LANDULFO, EDUARDO
This study employs surface and remote sensing data jointly with deep learning techniques to examine the influence of vehicular traffic in the seasonal patterns of CO, NO2 , PM2.5, and PM10 concentrations in the São Paulo municipality, as the period of physical distancing (March 2020 to December 2021), due to SARS-CoV-2 pandemic and the resumption of activities, made it possible to observe significant variations in the flow of vehicles in the city of São Paulo. Firstly, an analysis of the planetary boundary layer height and ventilation coefficient was performed to identify the seasons’ patterns of pollution dispersion. Then, the variations (from 2018 to 2021) of the seasonal average values of air temperature, relative humidity, precipitation, and thermal inversion occurrence/position were compared to identify possible variations in the patterns of such variables that would justify (or deny) the occurrence of more favorable conditions for pollutants dispersion. However, no significant variations were found. Finally, the seasonal average concentrations of the previously mentioned pollutants were compared from 2018 to 2021, and the daily concentrations observed during the pandemic period were compared with a model based on an artificial neural network. Regarding the concentration of pollutants, the primarily sourced from vehicular traffic (CO and NO2 ) exhibited substantial variations, demonstrating an inverse relationship with the rate of social distancing. In addition, the measured concentrations deviated from the predictive model during periods of significant social isolation. Conversely, pollutants that were not primarily linked to vehicular sources (PM2.5 and PM10) exhibited minimal variation from 2018 to 2021; thus, their measured concentration remained consistent with the prediction model.
Comparing lidar and ceilometer backscattering measurements for the detection of aerosol layers in the PBL over São Paulo, Brazil
2021 - SANTOS, AMANDA V.; LANDULFO, EDUARDO; MOREIRA, GREGORI A.; MARQUES, MARCIA T.A.; ANDRADE, MARIA F.
The Planetary Boundary Layer (PBL) is the lowest part of the troposphere and it is directly influenced by the Earth’s surface and anthropogenic activities. The concentration of aerosol in the PBL is typically much higher than in the free troposphere. Given that most of the air pollution in the troposphere is capped by this layer, obtaining the PBL height (PBLH) and its evolution during the day can assist in monitoring and studying aerosol concentrations and properties and its impact on air quality. Multi-instrument monitoring of the PBLH can assist in identifying the arrival of different air masses and tracking the evolution of aerosol layers during the day. Due to their lower cost, ceilometers can be powerful tools to enhance these measurements, although such an instrument has a few limitations when compared to lidars. The weaker laser light source used in ceilometers can limit the detection of aerosol layers to a few kilometers in height, depending on the presence and distribution of clouds and aerosols in the atmosphere. Given that some methods to estimate the PBLH need strong gradients in the concentration of aerosols to identify it correctly, the improper identification of the aerosol layers can become problematic for obtaining the PBLH. We compared lidar and ceilometer data from two instruments located in the city of São Paulo, Brazil, approximately 15 km from each other. We found that, in clear sky conditions, it is possible to correctly identify aerosol layers in the PBL with data from both instruments. The presence of clouds, signal attenuation and noise can sometimes cause errors in the identification of aerosol layers, especially when using ceilometer data. We found that, despite not being co-located, both instruments show similar profiles, up to a few kilometers in height.
Performance assessment of aerosol-lidar remote sensing skills to retrieve the time evolution of the urban boundary layer height in the Metropolitan Region of São Paulo City, Brazil
2022 - MOREIRA, GREGORI de A.; OLIVEIRA, AMAURI P. de; SANCHEZ, MACIEL P.; CODATO, GEORGIA; LOPES, FABIO J. da S.; LANDULFO, EDUARDO; MARQUES FILHO, EDSON P.
This paper investigates the performance of seven methods of retrieving the planetary boundary layer height (PBLH) from lidar measurements carried out in the Metropolitan Region of S˜ao Paulo (MRSP) during two MCITY-BRAZIL field campaigns of 2013. The performance is objectively assessed considering as reference the PBLH retrieved from rawinsonde carried out every 3 h during these campaigns. The role of clouds and aerosol load in the performance of the seven methods is analysed considering three case study scenarios representative of typical atmospheric conditions in the MRSP: (a) winter clean atmosphere, (b) summer low clouds and aerosol multilayers, (c) summer sea-breeze intrusion. Corroborating the case study results, the objective analysis indicated that most of the lidar methods retrieved PBLH closer to the top of the entrainment zone than the mixed layer, contradicting their definition. During daytime, the Wavelet Covariance Transform Method performs better than all the other six methods. The Inflexion Point Method performed better to estimate the Residual Layer height during night-time. In average, the diurnal evolution of the PBLH and its local rate of change based on lidar and rawinsonde measurements are in agreement.
Assessing spatial variation of PBL height and aerosol layer aloft in São Paulo Megacity using simultaneously two lidar during winter 2019
2022 - MOREIRA, GREGORI de A.; OLIVEIRA, AMAURI P. de; CODATO, GEORGIA; SANCHEZ, MACIEL P.; TITO, JANET V.; SILVA, LEONARDO A.H. e; SILVEIRA, LUCAS C. da; SILVA, JONATAN J. da; LOPES, FABIO J. da S.; LANDULFO, EDUARDO
This work presents the use of two elastic lidar systems to assess the horizontal variation of the PBL height (PBLH) and aerosol layer aloft in the São Paulo Megacity. These two lidars performed simultaneous measurements 10.7 km apart in a highly urbanized and relatively flat area of São Paulo for two winter months of 2019. The results showed that the PBLH differences display diurnal variation that depends on the PBL during daytime growth phases. Cloud and sea breeze effects control most of PBLH variation. In the absence of cloud and sea breeze, the maximum difference (~300 m) occurs in the rapid development stage and is due to topographic effects. When the PBL approaches its maximum daily value, it tends to level off with respect to the topography. In addition, it was presented a method that combines elastic lidar (to detect an aerosol layer) and satellite data (to classify such a layer from Aerosol Optical Depth (AOD) and Aerosol Index (AI) information) for the detection of biomass burning events. This methodology demonstrated that the variations caused by Biomass Burning in AOD and AI enable both the detection of aerosol plumes originating from biomass burning and the identification of their origin.
Aerosol number fluxes and concentrations over a southern European urban area
2022 - CASQUERO-VERA, J.A.; LYAMANI, H.; TITOS, G.; MOREIRA, G. de A.; BENAVENT-OLTRA, J.A.; CONTE, M.; CONTINI, D.; JARVI, L.; OLMO-REYES, F.J.; ALADOS-ARBOLEDAS, L.
Although cities are an important source of aerosol particles, aerosol number flux measurements over urban areas are scarce. These measurements are however important as they can allow us to identify the different sources/sinks of aerosol particles and quantify their emission contributions. Therefore, they can help us to understand the aerosol impacts on human health and climate, and to design effective mitigation strategies through the reduction of urban aerosol emissions. In this work we analyze the aerosol number concentrations and fluxes for particles with diameters larger than 2.5 nm measured by eddy covariance technique at an urban area (Granada city, Spain) from November 2016 to April 2018. This is the first study of particle number flux in an urban area in the Iberian Peninsula and is one of the few current studies that report long-term aerosol number flux measurements. The results suggest that, on average, Granada urban area acted as a net source for atmospheric aerosol particles with median particle number flux of 150 × 106 m−2 s−1. Downward negative fluxes were observed in only 12% of the analyzed data, and most of them were observed during high aerosol load conditions. Both aerosol number fluxes and concentrations were maximum in winter and 50% larger than those measured in summer due to the increased emissions from domestic heating, burning of residual agricultural waste in the agricultural area surrounding the site, as well as to the lower aerosol dilution effects during winter. The analysis of the seasonal diurnal variability of the aerosol number concentration revealed the significant impact of traffic emissions on aerosol population over Granada urban area in all seasons. It also shows the impact of domestic heating and agricultural waste burning emissions in winter as well as the influence of new particle formation processes in summer and spring seasons. Closer analysis by wind sector demonstrated that both aerosol concentrations and fluxes from urban sector (where high density of anthropogenic sources is located) were lower than those from rural sector (which includes agricultural area but also the main highway of the city). This evidences the strong impact of aerosol emissions from traffic circulating on the highway on aerosol population over our measurement site.
Lidar observations in South America
2021 - LANDULFO, EDUARDO; CACHEFFO, ALEXANDRE; YOSHIDA, ALEXANDRE C.; GOMES, ANTONIO A.; LOPES, FABIO J. da S.; MOREIRA, GREGORI de A.; SILVA, JONATAN J. da; ANDRIOLI, VANIA; PIMENTA, ALEXANDRE; WANG, CHI; XU, JIYAO; MARTINS, MARIA P.P.; BATISTA, PAULO; BARBOSA, HENRIQUE de M.J.; GOUVEIA, DIEGO A.; GONZALEZ, BORIS B.; ZAMORANO, FELIX; QUEL, EDUARDO; PEREIRA, CLODOMYRA; WOLFRAM, ELIAN; CASASOLA, FACUNDO I.; ORTE, FACUNDO; SALVADOR, JACOBO O.; PALLOTTA, JUAN V.; OTERO, LIDIA A.; PRIETO, MARIA; RISTORI, PABLO R.; BRUSCA, SILVINA; ESTUPINAN, JOHN H.R.; BARRERA, ESTIVEN S.; ANTUNA-MARRERO, JUAN C.; FORNO, RICARDO; ANDRADE, MARCOS; HOELZEMANN, JUDITH J.; GUEDES, ANDERSON G.; SOUSA, CRISTINA T.; OLIVEIRA, DANIEL C.F. dos S.; DUARTE, EDICLE de S.F.; SILVA, MARCOS P.A. da; SANTOS, RENATA S. da S.
In Part II of this chapter, we intend to show the significant advances and results concerning aerosols’ tropospheric monitoring in South America. The tropospheric lidar monitoring is also supported by the Latin American Lidar Network (LALINET). It is concerned about aerosols originating from urban pollution, biomass burning, desert dust, sea spray, and other primary sources. Cloud studies and their impact on radiative transfer using tropospheric lidar measurements are also presented.
Lidar observations in South America
2021 - LANDULFO, EDUARDO; CACHEFFO, ALEXANDRE; YOSHIDA, ALEXANDRE C.; GOMES, ANTONIO A.; LOPES, FABIO J. da S.; MOREIRA, GREGORI de A.; SILVA, JONATAN J. da; ANDRIOLI, VANIA; PIMENTA, ALEXANDRE; WANG, CHI; XU, JIYAO; MARTINS, MARIA P.P.; BATISTA, PAULO; BARBOSA, HENRIQUE de M.J.; GOUVEIA, DIEGO A.; GONZALEZ, BORIS B.; ZAMORANO, FELIX; QUEL, EDUARDO; PEREIRA, CLODOMYRA; WOLFRAM, ELIAN; CASASOLA, FACUNDO I.; ORTE, FACUNDO; SALVADOR, JACOBO O.; PALLOTTA, JUAN V.; OTERO, LIDIA A.; PRIETO, MARIA; RISTORI, PABLO R.; BRUSCA, SILVINA; ESTUPINAN, JOHN H.R.; BARRERA, ESTIVEN S.; ANTUNA-MARRERO, JUAN C.; FORNO, RICARDO; ANDRADE, MARCOS; HOELZEMANN, JUDITH J.; GUEDES, ANDERSON G.; SOUSA, CRISTINA T.; OLIVEIRA, DANIEL C.F. dos S.; DUARTE, EDICLE de S.F.; SILVA, MARCOS P.A. da; SANTOS, RENATA S. da S.
South America covers a large area of the globe and plays a fundamental function in its climate change, geographical features, and natural resources. However, it still is a developing area, and natural resource management and energy production are far from a sustainable framework, impacting the air quality of the area and needs much improvement in monitoring. There are significant activities regarding laser remote sensing of the atmosphere at different levels for different purposes. Among these activities, we can mention the mesospheric probing of sodium measurements and stratospheric monitoring of ozone, and the study of wind and gravity waves. Some of these activities are long-lasting and count on the support from the Latin American Lidar Network (LALINET). We intend to pinpoint the most significant scientific achievements and show the potential of carrying out remote sensing activities in the continent and show its correlations with other earth science connections and synergies. In Part I of this chapter, we will present an overview and significant results of lidar observations in the mesosphere and stratosphere. Part II will be dedicated to tropospheric observations.