ALEXANDRE CACHEFFO

ALEXANDRE CACHEFFO

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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.
Study of aerosol optical properties on South America using AERONET data analysis
2021 - JESUS, ESTER O. de; ROSARIO, NILTON M.E. do; YOSHIDA, ALEXANDRE C.; CACHEFFO, ALEXANDRE; GUERRERO-RASCADO, JUAN L.; LANDULFO, EDUARDO; LOPES, FABIO J.S.
In the last decade, a new generation of satellite missions have been developed using advanced lidar systems capable to retrieve several cloud and aerosol optical properties and distinguish different aerosol types by applying a polarization sensitive high spectral resolution lidar (HSRL) technique, as is the case of the Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) mission, developed by the European Space Agency (ESA) together with the Japan Aerospace Exploration Agency (JAXA). The EarthCARE payload will be compound by four main instruments, a cloud profiling radar, with Doppler capability, the HSRL system, a multispectral imager and a broadband radiometer, enabling the retrieval of global profiles of clouds, aerosols, precipitation and radiation field properties. The Atmospheric Lidar system (ATLID) on board of EarthCARE will operate at 355 nm and will use the cross and co-polarized components of Mie and Rayleigh scattering to derive aerosol properties. An important task to be developed by ground-based research groups is the data validation process. In this context, the Latin American LIdar NETwork (LALINET) has been playing a key role in the cloud and aerosol studies by using lidar and/or the AERONET sunphotometers data. In order to prepare the most suitable strategy for calibration and validation (CAL/VAL) processes of the EarthCARE mission, we have employed an extensive study of aerosol optical properties derived from 21 AERONET sunphotometer stations all over South America, from a period of at least 20 year. The aim of this work is to present preliminary results of columnar aerosol optical properties, such as AOD, lidar ratio, scattering and absorption Angstrom Exponent, single-scaterring albedo and aerosol fine-mode fraction, in order to select cluster-zones by aerosol types to guide the validation methodology for ATLID system products, since the continent is dominated by high spatial and temporal variability of aerosol systems.
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.
AEOLUS calibration and validation activities at SPU Lidar Station - Brazil
2020 - YOSHIDA, A.C.; LOPES, F.J.S.; CACHEFFO, A.; MOREIRA, G.A.; SILVA, J.J. da; LANDULFO, E.
Validation of AEOLUS L2A products using a multiwavelength lidar system at SPU Lidar Station - Brazil
2020 - LOPES, FABIO; YOSHIDA, ALEXANDRE; CACHEFFO, ALEXANDRE; SILVA, JONATAN; MOREIRA, GREGORI; LANDULFO, EDUARDO
Overview of the 2019 Sentinel-5p TROpomi vaLIdation eXperiment (TROLIX)
2020 - APITULEY, ARNOUD; KREHER, KARIN; PITERS, ANKIE; SULLIVAN, JOHN; VAN ROOZENDAEL, MICHEL; VLEMMIX, TIM; DEN HOED, MIRJAM; FRUMAU, ARNOUD; HENZING, BAS; SPEET, BART; VONK, JAN; VEEFKIND, PEPIJN; ALVES, DIEGO; CACHEFFO, ALEXANDRE; STEIN-ZWEERS, DEBORAH; ALLAART, MARC; ESKES, HENK; VAN DER ENT, FLORIS; SALEEB, GEORGE; MCGEE, TOM; TWIGG, LARRY; SUMNICHT, GRANT; HENDRICK, FRANCOIS; MERLAUD, ALEXIS; FAYT, CAROLINE; HERMANS, CHRISTIAN; PINARDI, GAIA; DORNER, STEFFEN; WAGNER, THOMAS; LAUSTER, BIANCA; UBELE, ALMA; MENDES, ALEX; LOPES, FABIO; LANDULFO, EDUARDO; SPINEI, ELENA; QUEREL, RICHARD; KARAGKIOZIDIS, DIMITRIS; BAIS, ALKIS; HUTJES, RONALD
For the validation of Sentinel-5p/TROPOMI the TROpomi vaLIdation eXperiment (TROLIX) was held in the Netherlands based at the Cabauw Experimental Site for Atmospheric Research during September 2019. TROLIX consisted of active and passive remote sensing platforms in conjunction with several balloon-borne and surface measurements. The intensive observations will serve to establish the quality of TROPOMI L2 main data products (UVAI, Aerosol Layer Height, NO2, O3, HCHO, Clouds) under realistic conditions with varying cloud cover and a wide range of atmospheric conditions. Since TROPOMI is a hyperspectral imager with a very high spatial resolution of 3.6 x 5.6 km2, understanding local effects such as inhomogeneous sources of pollution, sub-pixel clouds and variations in ground albedo is important to interpret TROPOMI results. Therefore, the campaign included sub-pixel resolution local networks of sensors, involving MAXDOAS and Pandora instruments, around Cabauw (rural) and within the city of Rotterdam (urban). Utilising its comprehensive in-situ and remote sensing observation program in and around the 213 m meteorological tower, Cabauw was the main site of the campaign with focus on vertical profiling using lidar instruments for aerosols, clouds, water vapor, tropospheric and stratospheric ozone, as well as balloon-borne sensors for NO2 and ozone. The data set collected can be directly compared to the TROPOMI L2 data products, while measurements of parameters related to a-priori data and auxiliary parameters that infuence the quality of the L2 products such as aerosol and cloud profiles and in-situ aerosol and atmospheric chemistry were also collected.
COVID-19 outbreak and air quality
2021 - MOREIRA, GREGORI de A.; ANDRADE, IZABEL da S.; CACHEFFO, ALEXANDRE; YOSHIDA, ALEXANDRE C.; GOMES, ANTONIO A.; SILVA, JONATAN J. da; LOPES, FABIO J. da S.; LANDULFO, EDUARDO
This work compares variations in the concentrations and air quality indexes of the pollutants PM10, PM2.5, CO, and NO2, during the COVID-19 outbreak in São Paulo Municipality. Such comparisons considered the period of physical distancing (autumn) and the three first months of economic activities’ resumption (winter). The concentrations and indexes observed in 2020 were compared with their correspondent values measured in the three preceding years. Also, from a supervised machine learning algorithm, the correspondent 2020 expected values were predicted and used in these comparisons. In order to analyze the influence of meteorological conditions, the seasons studied were characterized using remote sensing and surface data. The pollutants predominantly emitted by the vehicle fleet (CO and NO2) had reductions in their concentrations, with values always below the predictions and good air quality indexes. However, the pollutants whose concentration is less dependent on automotive emissions (PM10 and PM2.5) had high proximity to the predictions during the autumn and lower values during some periods in winter. This reduction was not enough to avoid days with a moderate air quality index. The approximation of the average concentrations of PM10, PM2.5, and CO to the prediction, from the second-half August 2020, indicates the influence of activities’ resumption in air quality.
Influence of a biomass-burning event in PM2.5 concentration and air quality
2021 - MOREIRA, GREGORI de A.; ANDRADE, IZABEL da S.; CACHEFFO, ALEXANDRE; LOPES, FABIO J. da S.; YOSHIDA, ALEXANDRE C.; GOMES, ANTONIO A.; SILVA, JONATAN J. da; LANDULFO, EDUARDO
Severe biomass burning (BB) events have become increasingly common in South America in the last few years, mainly due to the high number of wildfires observed recently. Such incidents can negatively influence the air quality index associated with PM2.5 (particulate matter, which is harmful to human health). A study performed in the Metropolitan Area of São Paulo (MASP) took place on selected days of July 2019, evaluated the influence of a BB event on air quality. Use of combined remote sensing, a surface monitoring system and data modeling and enabled detection of the BB plume arrival (light detection and ranging (lidar) ratio of (50 ± 34) sr at 532 nm, and (72 ± 45) sr at 355 nm) and how it affected the Ångström exponent (>1.3), atmospheric optical depth (>0.7), PM2.5 concentrations (>25 µg.m−3), and air quality classification. The utilization of high-order statistical moments, obtained from elastic lidar, provided a new way to observe the entrainment process, allowing understanding of how a decoupled aerosol layer influences the local urban area. This new novel approach enables a lidar system to obtain the same results as a more complex set of instruments and verify how BB events contribute from air masses aloft towards near ground ones.

ALEXANDRE CACHEFFO

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