Navegação Periódicos - Artigos por autor "10204"

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  • IPEN-DOC 28656

    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.. Aerosol number fluxes and concentrations over a southern European urban area. Atmospheric Environment, v. 269, p. 1-10, 2022. DOI: 10.1016/j.atmosenv.2021.118849

    Abstract: 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.

    Palavras-Chave: urban areas; aerosols; concentration ratio; atmospheres; particles; eddy currents; data covariances

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  • IPEN-DOC 26404

    MOREIRA, GREGORI de A. ; LOPES, FABIO J. da S. ; GUERRERO-RASCADO, JUAN L.; SILVA, JONATAN J. da ; GOMES, ANTONIO A. ; LANDULFO, EDUARDO ; ALADOS-ARBOLEDAS, LUCAS. Analyzing the atmospheric boundary layer using high-order moments obtained from multiwavelength lidar data: impact of wavelength choice. Atmospheric Measurement Techniques, v. 12, n. 8, p. 4261-4276, 2019. DOI: 10.5194/amt-12-4261-2019

    Abstract: The lowest region of the troposphere is a turbulent layer known as the atmospheric boundary layer (ABL) and characterized by high daily variability due to the influence of surface forcings. This is the reason why detecting systems with high spatial and temporal resolution, such as lidar, have been widely applied for researching this region. In this paper, we present a comparative analysis on the use of lidar-backscattered signals at three wavelengths (355, 532 and 1064 nm) to study the ABL by investigating the highorder moments, which give us information about the ABL height (derived by the variance method), aerosol layer movement (skewness) and mixing conditions (kurtosis) at several heights. Previous studies have shown that the 1064 nm wavelength, due to the predominance of particle signature in the total backscattered atmospheric signal and practically null presence of molecular signal (which can represent noise in high-order moments), provides an appropriate description of the turbulence field, and thus in this study it was considered a reference. We analyze two case studies that show us that the backscattered signal at 355 nm, even after applying some corrections, has a limited applicability for turbulence studies using the proposed methodology due to the strong contribution of the molecular signature to the total backscatter signal. This increases the noise associated with the high-order profiles and, consequently, generates misinformation. On the other hand, the information on the turbulence field derived from the backscattered signal at 532 nm is similar to that obtained at 1064 nm due to the appropriate attenuation of the noise, generated by molecular component of backscattered signal by the application of the corrections proposed.

    Palavras-Chave: troposphere; optical radar; boundary layers; atmospheres; aerosols; turbulence; air quality; monitoring

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  • IPEN-DOC 29836

    MOREIRA, GREGORI de A. ; CACHEFFO, ALEXANDRE ; ANDRADE, IZABEL da S. ; LOPES, FABIO JULIANO da S. ; GOMES, ANTONIO A. ; LANDULFO, EDUARDO . Analyzing the influence of vehicular traffic on the concentration of pollutants in the city of São Paulo: an approach based on pandemic SARS-CoV-2 data and deep learning. Atmosphere, v. 14, n. 10, p. 1-16, 2023. DOI: 10.3390/atmos14101578

    Abstract: 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.

    Palavras-Chave: urban areas; air pollution; air quality; machine learning; vehicles; coronaviruses

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  • IPEN-DOC 25711

    MOREIRA, GREGORI de A. ; GUERRERO-RASCADO, JUAN L.; BENAVENT-OLTRA, JOSE A.; ORTIZ-AMEZCUA, PABLO; ROMAN, ROBERTO; BEDOYA-VELASQUEZ, ANDRES E.; BRAVO-ARANDA, JUAN A.; REYES, FRANCISCO J.O.; LANDULFO, EDUARDO ; ALADOS-ARBOLEDAS, LUCAS. Analyzing the turbulent planetary boundary layer by remote sensing systems: the Doppler wind lidar, aerosol elastic lidar and microwave radiometer. Atmospheric Chemistry and Physics, v. 19, n. 2, p. 1263-1280, 2019. DOI: 10.5194/acp-19-1263-2019

    Abstract: The planetary boundary layer (PBL) is the lowermost region of troposphere and is endowed with turbulent characteristics, which can have mechanical and/or thermodynamic origins. This behavior gives this layer great importance, mainly in studies about pollutant dispersion and weather forecasting. However, the instruments usually applied in studies of turbulence in the PBL have limitations in spatial resolution (anemometer towers) or temporal resolution (instrumentation aboard an aircraft). Ground-based remote sensing, both active and passive, offers an alternative for studying the PBL. In this study we show the capabilities of combining different remote sensing systems (microwave radiometer – MWR, Doppler lidar – DL – and elastic lidar – EL) for retrieving a detailed picture on the PBL turbulent features. The statistical moments of the high frequency distributions of the vertical wind velocity, derived from DL, and of the backscattered coefficient, derived from EL, are corrected by two methodologies, namely first lag correction and 􀀀2=3 law correction. The corrected profiles, obtained from DL data, present small differences when compared with the uncorrected profiles, showing the low influence of noise and the viability of the proposed methodology. Concerning EL, in addition to analyzing the influence of noise, we explore the use of different wavelengths that usually include EL systems operated in extended networks, like the European Aerosol Research Lidar Network (EARLINET), Latin American Lidar Network (LALINET), NASA Micro-Pulse Lidar Network (MPLNET) or Skyradiometer Network (SKYNET). In this way we want to show the feasibility of extending the capability of existing monitoring networks without strong investments or changes in their measurements protocols. Two case studies were analyzed in detail, one corresponding to a well-defined PBL and another corresponding to a situation with presence of a Saharan dust lofted aerosol layer and clouds. In both cases we discuss results provided by the different instruments showing their complementarity and the precautions to be applied in the data interpretation. Our study shows that the use of EL at 532 nm requires a careful correction of the signal using the first lag time correction in order to get reliable turbulence information on the PBL.

    Palavras-Chave: boundary layers; troposphere; planetary atmospheres; doppler effect; wind; optical radar; monitoring; microwave radiation; radiometers; aerosols; elastic scattering; remote sensing

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  • IPEN-DOC 28812

    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 . Assessing spatial variation of PBL height and aerosol layer aloft in São Paulo Megacity using simultaneously two lidar during winter 2019. Atmosphere, v. 13, n. 4, p. 1-16, 2022. DOI: 10.3390/atmos13040611

    Abstract: 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.

    Palavras-Chave: boundary layers; earth atmosphere; biomass; burns; urban areas; optical radar

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  • IPEN-DOC 27244

    MOREIRA, GREGORI de A. ; LOPES, FABIO J. da S. ; GUERRERO-RASCADO, JUAN L.; ORTIZ-AMEZCUA, PABLO; CAZORLA, ALBERTO; OLIVEIRA, AMAURI P. de; LANDULFO, EDUARDO ; ALADOS-ARBOLEDAS, LUCAS. Comparison among the atmospheric boundary layer height estimated from three different tracers. EPJ Web of Conferences, v. 237, p. 1-4, 2020. DOI: 10.1051/epjconf/202023703009

    Abstract: The Atmospheric Boundary Layer (ABL) is the lowermost part of the troposphere. In this work, we analysed the combination of ABL height estimated continuously by three different remote sensing systems: a ceilometer, a Doppler lidar and a passive Microwave Radiometer, during a summer campaign, which was held in Granada from June to August 2016. This study demonstrates as the combined utilization of remote sensing systems, based on different tracers, can provide detailed information about the height of ABL and their sublayers.

    Palavras-Chave: atmospheres; doppler effect; boundary layers; troposphere; optical radar; microwave radiation; radiometers

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  • IPEN-DOC 27830

    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 . COVID-19 outbreak and air quality: analyzing the influence of physical distancing and the resumption of activities in São Paulo municipality. Urban Climate, v. 37, p. 1-15, 2021. DOI: 10.1016/j.uclim.2021.100813

    Abstract: 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.

    Palavras-Chave: coronaviruses; urban areas; urban populations; emergency plans; air quality; air pollution monitors; pollution sources; optical radar

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  • IPEN-DOC 26653

    BENAVENT-OLTRA, JOSE A.; ROMAN, ROBERTO; CASQUERO-VERA, JUAN A.; PEREZ-RAMIREZ, DANIEL; LYAMANI, HASSAN; ORTIZ-AMEZCUA, PABLO; BEDOYA-VELASQUEZ, ANDRES E.; MOREIRA, GREGORI de A. ; BARRETO, AFRICA; LOPATIN, ANTON; FUERTES, DAVID; HERRERA, MILAGROS; TORRES, BENJAMIN; DUBOVIK, OLEG; GUERRERO-RASCADO, JUAN L.; GOLOUB, PHILIPPE; OLMO-REYES, FRANCISCO J.; ALADOS-ARBOLEDAS, LUCAS. Different strategies to retrieve aerosol properties at night-time with the GRASP algorithm. Atmospheric Chemistry and Physics, v. 19, n. 22, p. 14149-14171, 2019. DOI: 10.5194/acp-19-14149-2019

    Abstract: This study evaluates the potential of the GRASP algorithm (Generalized Retrieval of Aerosol and Surface Properties) to retrieve continuous day-to-night aerosol properties, both column-integrated and vertically resolved. The study is focused on the evaluation of GRASP retrievals during an intense Saharan dust event that occurred during the Sierra Nevada Lidar aerOsol Profiling Experiment I (SLOPE I) field campaign. For daytime aerosol retrievals, we combined the measurements of the ground-based lidar from EARLINET (European Aerosol Research Lidar Network) station and sun–sky photometer from AERONET (Aerosol Robotic Network), both instruments co-located in Granada (Spain). However, for night-time retrievals three different combinations of active and passive remote-sensing measurements are proposed. The first scheme (N0) uses lidar night-time measurements in combination with the interpolation of sun–sky daytime measurements. The other two schemes combine lidar night-time measurements with nighttime aerosol optical depth obtained by lunar photometry either using intensive properties of the aerosol retrieved during sun–sky daytime measurements (N1) or using the Moon aureole radiance obtained by sky camera images (N2). Evaluations of the columnar aerosol properties retrieved by GRASP are done versus standard AERONET retrievals. The coherence of day-to-night evolutions of the different aerosol properties retrieved by GRASP is also studied. The extinction coefficient vertical profiles retrieved by GRASP are compared with the profiles calculated by the Raman technique at night-time with differences below 30% for all schemes at 355, 532 and 1064 nm. Finally, the volume concentration and scattering coefficient retrieved by GRASP at 2500ma.s.l. are evaluated by in situ measurements at this height at Sierra Nevada Station. The differences between GRASP and in situ measurements are similar for the different schemes, with differences below 30% for both volume concentration and scattering coefficient. In general, for the scattering coefficient, the GRASP N0 and N1 show better results than the GRASP N2 schemes, while for volume concentration, GRASP N2 shows the lowest differences against in situ measurements (around 10 %) for high aerosol optical depth values.

    Palavras-Chave: algorithms; aerosol monitoring; surface properties; dusts; optical properties; optical radar; deserts; aerosol wastes; raman effect

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  • IPEN-DOC 27251

    SILVA, JONATAN da ; MORAIS, FERNANDO G. ; FRANCO, MARCO A.; LOPES, FABIO J.S. ; ARRUDA, GREGORI de A. ; YOSHIDA, ALEXANDRE C. ; CORREIA, ALEXANDRE; LANDULFO, EDUARDO . Exploring the twilight zone: a multi-sensor approach. EPJ Web of Conferences, v. 237, p. 1-4, 2020. DOI: 10.1051/epjconf/202023707015

    Abstract: This study shows a set of analysis of measurements from ground-based and satellite instruments to characterize the twilight zone (TLZ) between clouds and aerosols in São Paulo, Brazil. In the vicinity of clouds turbulence measurements showed an intense upward movement of aerosol layers, while sunphotometer results showed an increase in aerosol optical depth, and lidar measurements showed an increase in the backscatter vertical profile signal.

    Palavras-Chave: atmospheres; clouds; earth atmosphere; aerosols; optical radar; satellites; urban areas; radiations; meteorology

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  • IPEN-DOC 29945

    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.. Impact of extreme wildfires from the Brazilian Forests and sugarcane burning on the air quality of the biggest megacity on South America. Science of the Total Environment, v. 888, p. 1-10, 2023. DOI: 10.1016/j.scitotenv.2023.163439

    Abstract: 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.

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  • IPEN-DOC 27755

    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 . Influence of a biomass-burning event in PM2.5 concentration and air quality: a case study in the Metropolitan Area of São Paulo. Sensors, v. 21, n. 2, p. 1-19, 2021. DOI: 10.3390/s21020425

    Abstract: 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.

    Palavras-Chave: air quality; biomass; burns; particulates; remote sensing; moments method; statistics; nature reserves; optical radar

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  • IPEN-DOC 27253

    LANDULFO, EDUARDO ; VEGA, ALBEHT R.; YOSHIDA, ALEXANDRE C. ; BASTIDAS, ALVARO; SANTOS, AMANDA V. dos; SILVA, ANTONIETA; GOMES, ANTONIO A. ; GONZALEZ, BORIS B.; MELO-LUNA, CARLOS A.; HOYOS, CARLOS D.; RAE, CRISTINA T. de S.; CAMILO, DANIEL; VIVAS, DAVID; GOUVEIA, DIEGO A.; WOLFRAM, ELIAN; COLLINI, ESTELA; LOPES, FABIO J.S. ; MOREIRA, GREGORI de A. ; BARBOSA, HENRIQUE de M.J.; CIMINARI, HERNAN; REINA, JOHN H.; SILVA, JONATAN J. da ; CESPEDES, JONNATHAN; MARRERO, JUAN C.A.; RASCADO, JUAN L.G.; PALLOTTA, JUAN; HOELZEMANN, JUDITH; ARBOLEDAS, LUCAS A.; SALLES, M.ALEJANDRA; SILVA, MARCOS P.A. da; SAMMARA, RENATA; FORNO, RICARDO N.; PAPANDREA, SEBASTIAN. LALINET network status. EPJ Web of Conferences, v. 237, p. 1-4, 2020. DOI: 10.1051/epjconf/202023705008

    Abstract: LALINET (Latin American Lidar Network) follows its goal to consolidation as a federative lidar network to provide regional coverage over Latin America in providing aerosol and greenhouse gas profiles following QA/QC protocols and promoting the development of researchers and students in atmopheric science field. We show recent results on different approaches for studying the optical properties of the atmosphere regarding aerosols at tropospheric and stratospheric level and greenhouse gas mixing ratio profiles followed by our recent support and validation efforts towards present and future satellite missions.

    Palavras-Chave: computer networks; optical radar; inventories; monitoring; optical properties; distribution

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  • IPEN-DOC 28813

    MOREIRA, GREGORI de A. ; OLIVEIRA, AMAURI P. de; SANCHEZ, MACIEL P.; CODATO, GEORGIA; LOPES, FABIO J. da S. ; LANDULFO, EDUARDO ; MARQUES FILHO, EDSON P.. 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. Atmospheric Research, v. 277, p. 1-16, 2022. DOI: 10.1016/j.atmosres.2022.106290

    Abstract: 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.

    Palavras-Chave: aerosols; remote sensing; optical radar; urban areas; boundary layers

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  • IPEN-DOC 26501

    SOUPIONA, O.; SAMARAS, S.; ORTIZ-AMEZCUA, P.; BOCKMANN, C.; PAPAYANNIS, A.; MOREIRA, G.A. ; BENAVENT-OLTRA, J.A.; GUERRERO-RASCADO, J.L.; BEDOYA-VELASQUEZ, A.E.; OLMO, F.J.; ROMAN, R.; KOKKALIS, P.; MYLONAKI, M.; ALADOS-ARBOLEDAS, L.; PAPANIKOLAOU, C.A.; FOSKINIS, R.. Retrieval of optical and microphysical properties of transported Saharan dust over Athens and Granada based on multi-wavelength Raman lidar measurements: study of the mixing processes. Atmospheric Environment, v. 214, p. 1-15, 2019. DOI: 10.1016/j.atmosenv.2019.116824

    Abstract: In this paper we extract the aerosol microphysical properties for a collection of mineral dust cases measured by multi-wavelength depolarization Raman lidar systems located at the National Technical University of Athens (NTUA, Athens, Greece) and the Andalusian Institute for Earth System Research (IISTA-CEAMA, Granada, Spain). The lidar-based retrievals were carried out with the Spheroidal Inversion eXperiments software tool (SphInX) developed at the University of Potsdam (Germany). The software uses regularized inversion of a two-dimensional enhancement of the Mie model based on the spheroid-particle approximation with the aspect ratio determining the particle shape. The selection of the cases was based on the transport time from the source regions to the measuring sites. The aerosol optical depth as measured by AERONET ranged from 0.27 to 0.54 (at 500 nm) depending on the intensity of each event. Our analysis showed the hourly mean particle linear depolarization ratio and particle lidar ratio values at 532 nm ranging from 11 to 34% and from 42 to 79 sr respectively, depending on the mixing status, the corresponding air mass pathways and their transport time. Cases with shorter transport time showed good agreement in terms of the optical and SphInXretrieved microphysical properties between Athens and Granada providing a complex refractive index value equal to 1.4 + 0.004i. On the other hand, the results for cases with higher transport time deviated from the aforementioned ones as well as from each other, providing, in particular, an imaginary part of the refractive index ranging from 0.002 to 0.005. Reconstructions of two-dimensional shape-size distributions for each selected layer showed that the dominant effective particle shape was prolate with diverse spherical contributions. The retrieved volume concentrations reflect overall the intensity of the episodes.

    Palavras-Chave: aerosols; minerals; dusts; aerial monitoring; deserts; optical radar; depolarization; computer codes; aerosol monitoring

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  • IPEN-DOC 25822

    BEDOYA-VELASQUEZ, ANDRES E.; NAVAS-GUZMAN, FRANCISCO; MOREIRA, GREGORI de A. ; ROMAN, ROBERTO; CAZORLA, ALBERTO; ORTIZ-AMEZCUA, PABLO; BENAVENT-OLTRA, JOSE A.; ALADOS-ARBOLEDAS, LUCAS; OLMO-REYES, FRANCISCO J.; FOYO-MORENO, INMACULADA; MONTILLA-ROSERO, ELENA; HOYOS, CARLOS D.; GUERRERO-RASCADO, JUAN L.. Seasonal analysis of the atmosphere during five years by using microwave radiometry over a mid-latitude site. Atmospheric Research, v. 218, p. 78-89, 2019. DOI: 10.1016/j.atmosres.2018.11.014

    Abstract: This work focuses on the analysis of the seasonal cycle of temperature and relative humidity (RH) profiles and integrated water vapor (IWV) obtained from microwave radiometer (MWR) measurements over the mid-latitude city of Granada, southern Spain. For completeness the study, the maximum atmospheric boundary layer height (ABLHmax) is also included. To this end, we have firstly characterized the HATPRO-RPG MWR errors using 55 colocated radiosondes (RS) by means of the mean-bias (bias) profile and the standard deviation (SDbias) profile classified under all-weather conditions and cloud-free conditions. This characterization pointed out that temperature from HATPRO-MWR presents a very low bias respects RS mostly below 2.0 km agl, ranging from positive to negative values under all-weather conditions (from 1.7 to −0.4 K with SDbias up to 3.0 K). Under cloud-free conditions, the bias was very similar to that found under allweather conditions (1.8 to −0.4 K) but with smaller SDbias (up to 1.1 K). The same behavior is also seen in this lower part (ground to 2.0 km agl) for RH. Under all-weather conditions, the mean RH bias ranged from 3.0 to −4.0% with SDbias between 10 and 16.3% while under cloud-free conditions the bias ranged from 2.0 to −0.4% with SDbias from 0.5 to 13.3%. Above 2.0 km agl, the SDbias error increases considerably up to 4 km agl (up to −20%), and then decreases slightly above 7.0 km agl (up to−5%). In addition, IWV values from MWR were also compared with the values obtained from the integration of RS profiles, showing a better linear fit under cloudfree conditions (R2=0.96) than under all-weather conditions (R2=0.82). The mean bias under cloud-free conditions was −0.80 kg/m2 while for all-weather conditions it was −1.25 kg/m2. Thus, the SDbiasfor all the statistics (temperature, RH and IWV) of the comparison between MWR and RS presented higher values for allweather conditions than for cloud-free conditions ones. It points out that the presence of clouds is a key factor to take into account when MWR products are used. The second part of this work is devoted to a seasonal variability analysis over five years, leading us to characterize thermodynamically the troposphere over our site. This city atmosphere presents a clear seasonal cycle where temperature, ABLHmax and IWV increase from winter to summer and decrease in autumn, meanwhile RH decreases along the warmer seasons. This city presents cold winters (mean daily maximum temperature: 10.6 ± 1.1 °C) and dry/hot summers (mean daily maximum temperature of 28.8 ± 0.9 °C and mean daily maximum of surface RH up to 55.0 ± 6.0%) at surface (680m asl). Moreover, considering temporal trends, our study pointed out that only temperature and RH showed a linear increase in winters with a mean-rate of (0.5 ± 0.1) °C/year and (3.4 ± 1.7) %/year, respectively, from ground to 2.0 km agl, meanwhile IWV presented a linear increase of 1.0 kg·m−2/year in winters, 0.78 kg·m−2/year in summers and a linear decrease in autumns of −0.75 kg·m−2/year.

    Palavras-Chave: microwave radiation; atmospheres; seasonal variations; remote sensing; thermodynamic properties; boundary layers; radiometers

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  • IPEN-DOC 27123

    MOREIRA, GREGORI de A. ; GUERRERO-RASCADO, JUAN L.; BRAVO-ARANDA, JUAN A.; FOYO-MORENO, INMACULADA; CAZORLA, ALBERTO; ALADOS, INMACULADA; LYAMANI, HASSAN; LANDULFO, EDUARDO ; ALADOS-ARBOLEDAS, LUCAS. Study of the planetary boundary layer height in an urban environment using a combination of microwave radiometer and ceilometer. Atmospheric Research, v. 240, p. 1-15, 2020. DOI: 10.1016/j.atmosres.2020.104932

    Abstract: The Planetary Boundary Layer (PBL) is an important part of the atmosphere that is relevant in different atmospheric fields like pollutant dispersion, and weather forecasting. In this study, we analyze four and five-year datasets of measurements gathered with a ceilometer and a microwave radiometer to study the PBL structure respectively, in the mid-latitude urban area of Granada (Spain). The methodologies applied for the PBL Height (PBLH) detection (gradient method for ceilometer and the combination of parcel method and temperature gradient method for microwave radiometer) provided a description in agreement with the literature about the PBL structure under simple scenarios. Then, the PBLH behavior is characterized by a statistical study of the convective and stable situations, so that the PBLH was obtained from microwave radiometer measurements. The analysis of the PBLH statistical study shows some agreement with other PBLH studies such as daily pattern and yearly cycle, and the discrepancies were explained in terms of distinct latitudes, topography and climate conditions. Finally, it was performed a joint long-term analysis of the residual layer (RL) provided by ceilometer and the stable and convective layer heights determined by microwave radiometer, offering a complete picture of the PBL evolution by synergetic combination of remote sensing techniques. The PBL behavior has been used for explaining the daily cycle of Black Carbon (BC) concentration, used as tracer of the pollutants emissions associated to traffic.

    Palavras-Chave: boundary layers; urban areas; atmospheres; clouds; microwave radiation; radiometers; weather; cloud cover; remote sensing; climates; monitoring

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