Classification of 2007 Winter Mist and Fog in São Paulo City, Brazil

Mist and fog observed at the Meteorological Station of the Institute of Astronomy, Geophysics and Atmospheric Sciences of the University of São Paulo (EM/IAG) in the southeastern part of São Paulo city in the winter of 2007 were classified according to its formation processes: advection or radiation. Meteorological data from EM/IAG, Congonhas Airport and reanalysis from the European Center for Medium-Range Weather Forecast, as well as radiosondes from Campo de Marte Airport were used. In the 1981-2015 climatology, it was observed that these phenomena are more frequent in the winter, with an average of 11 events per month. For the winter of 2007, 21 advection and 28 radiation events were detected, with radiation fog occurring more frequently in June (13) and advection fog, in August (12). The South Atlantic Subtropical High favored the formation of radiation events in 24 cases; 15 of which had the contribution of humidity advected by the sea breeze. Post-frontal anticyclone was associated with the remaining 25 cases, of which 15 were classified as advection. Four cases were chosen for a more detailed analysis. On July 2, 2007, radiation mist occurred, with the injection of moisture by the sea breeze; the next day, there was also radiation mist, however, with no sea breeze. On the 20th of July, fog was caused by advection of humidity with north/northeast winds coming from the Serra da Cantareira and on the 27th, advection mist developed due to the intensification of winds associated with the movement of a post-frontal anticyclone

Mesoscale Cyclonic Vortices Embedded in the South Atlantic Convergence Zone Associated with Natural Disasters in the State of São Paulo, Brazil

Natural disasters (NDs) have been observed more frequently and with increasing intensities in Brazil. The South Atlantic Convergence Zone (SACZ) is identified as one of the main meteorological systems responsible for the NDs, however, intense rainfall does not occur along its entire length but is restricted to some locations within the band of cloudiness that defines it. Thus, the objective of this study is to analyze occurrences of mesoscale cyclonic vortices (MCV) in SACZ events that were associated with NDs in the state of São Paulo from 2013 to 2017 using data from the ERA5 Reanalysis, as well as to analyze one case study. To account for SACZ events, surface synoptic charts, observed and estimated precipitation data were used. ND events were selected from the Integrated Disaster Information System (S2ID) database. The methodology used by Quadro (2012) was adapted to identify MCV. The results showed 62 SACZ events, of which 28 were associated with NDs, and, of these, 10 presented MCV. The MCVs were separated into two groups: 1) MCVs in the SACZ events that showed precipitation at the location of the MCV and NDs and 2) MCVs in the SACZ events that did not show precipitation at the location of the MCV and NDs. Group 1 events were characterized by convergence at low levels and divergence at high levels of the atmosphere, vorticity values lower than -8 x 10-4 s-1 predominating at low levels (850–900 hPa), demonstrating a relationship with the highest precipitation accumulations and possibly with the occurrence of NDs. In the events of group 2, there was a predominance of negative values of vorticity in medium and high levels, the lack of a pattern in the field of divergence in the atmospheric levels, as well as lower values in the accumulated precipitation compared to the events of group 1. The case study was from January 11 to 15, 2016, associated with NDs in 8 cities. As a result, it was obtained that MCV was coupled in the atmosphere and the precipitation associated with it represented more than 37% of all the precipitation of the SACZ event, making it possible to attribute to the MCV a contribution in the occurrence of NDs caused by precipitation.

Climate projections for South America: RegCM3 driven by HadCM3 and ECHAM5

This study shows climate projections of air temperature and precipitation over South America (SA) from the Regional Climate\ud Model version 3 (RegCM3) nested in ECHAM5 and HadCM3 global models. The projections consider the A1B scenario from\ud Intergovernmental Panel on Climate Change (IPCC) and three time-slices: present (1960–1990), near- (2010–2040), and far-future\ud (2070–2100) climates. In the future, RegCM3 projections indicate general warming throughout all SA and seasons, which is more\ud pronounced in the far-future period. In this late period the RegCM3 projections indicate that the negative trend of precipitation\ud over northern SA is also higher. In addition, a precipitation increase over southeastern SA is projected, mainly during summer\ud and spring. The lifecycle of the South American monsoon (SAM) was also investigated in the present and future climates. In the\ud near-future, the projections show a slight delay (one pentad) of the beginning of the rainy season, resulting in a small reduction of\ud the SAM length. In the far-future, there is no agreement between projections related to the SAM featuresCNPq - 307202/2011-9FAPESP - 2011/51016-9FAPEMIG - APQ-00251-11CAPESEuropean Community’s Seventh Framework Programme - FP7/2007–2013 - agreement n. 212492 (CLARIS LPB

Transporte de Poluentes pela Brisa Marítima em São Paulo sob a Alta do Atlântico Su

A circulação de brisa marítima e continental tem importância expressiva na Região Metropolitana de São Paulo (RMSP), influenciando a direção predominante do vento na escala diurna e podendo ocasionar transporte de poluentes. No verão de 2014, o ozônio ultrapassou os Padrões de Qualidade do Ar da CETESB durante 43 dias, quando a Alta Subtropical do Atlântico Sul se fortaleceu sobre a região Sudeste do Brasil. Buscou-se compreender como a brisa marítima e continental influenciaram o transporte dos poluentes CO, NO, NO2 e O3 na área de estudo, utilizando o modelo WRF/Chem, no período 28/01-01/02/2014. Foram construídos dois cenários: CTRL – emissões veiculares baseadas em inventários atuais de emissão de poluentes, e SENS – retirada de cerca de 75% das emissões na RMSP. A análise dos resultados, por meio de mapas com a distribuição espacial dos poluentes no domínio, demonstrou a importância da circulação de brisa para o transporte de poluição. A análise do campo de divergência mostrou-se útil para a identificação das frentes de brisa. Concentrações de O3 mais altas foram simuladas na região pré-frontal devido à estagnação e acúmulo de poluentes trazidos das áreas mais poluídas por onde a frente de brisa passou, ocasionando o transporte de ozônio para áreas distantes a noroeste durante a tarde. Ocorre também transporte de poluentes para sul durante o início da manhã com a brisa continental. O movimento ascendente do ar na região pré-frontal ocasionado pela convergência propicia o transporte vertical de ozônio durante a tarde.The land-sea breeze circulation is important for the Metropolitan Region of São Paulo (MRSP), influencing predominant wind direction during the night and day, and so, the transport of pollution in the local scale. In the summer of 2014, there were 43 exceedances of the state air quality by ozone, when the South Atlantic Subtropical High strengthened over southeast Brazil. We aimed to study how the land-sea breeze circulation influenced the transport of the pollutants CO, NO, NO2 and O3 in the study area using the WRF/Chem model in the period 28/01-01/02/2014. Two scenarios were considered: CTRL – vehicular emissions based on current emission inventories and SENS – removing 75% of emissions in the MRSP. Results were analysed through maps with the spatial distribution of pollutants in the domain and showed the importance of the land-sea breeze circulation for the transport of pollution. Analysis of the divergence field proved useful for identifying the sea breeze front. Higher O3 concentrations were simulated in the prefrontal convergence line, due to stagnation and accumulation of pollutants brought by the passage of the sea breeze over polluted areas, resulting in the transport of ozone and other pollutants to distant areas northwest during the afternoon and evening. There was also transport of pollutants to the south in the early morning caused by the land breeze. Upward air motion due to the convergence in the prefrontal region caused vertical transport of ozone during the afternoon

Formação e Transporte das Partículas Finas Inorgânicas em uma Atmosfera Urbana: O Exemplo de São Paulo

Formação e transporte das partículas finas inorgânicas emuma atmosfera urbana: o exemplo de São Paul

Physical–chemical characterisation of the particulate matter inside\ud two road tunnels in the São Paulo Metropolitan Area

The notable increase in biofuel usage by the road\ud transportation sector in Brazil during recent years has significantly\ud altered the vehicular fuel composition. Consequently,\ud many uncertainties are currently found in particulate\ud matter vehicular emission profiles. In an effort to better\ud characterise the emitted particulate matter, measurements\ud of aerosol physical and chemical properties were undertaken\ud inside two tunnels located in the São Paulo Metropolitan\ud Area (SPMA). The tunnels show very distinct fleet profiles:\ud in the Jânio Quadros (JQ) tunnel, the vast majority\ud of the circulating fleet are light duty vehicles (LDVs), fuelled\ud on average with the same amount of ethanol as gasoline.\ud In the Rodoanel (RA) tunnel, the particulate emission\ud is dominated by heavy duty vehicles (HDVs) fuelled with\ud diesel (5% biodiesel). In the JQ tunnel, PM2.5 concentration\ud was on average 52 μgm−3, with the largest contribution\ud of organic mass (OM, 42 %), followed by elemental carbon\ud (EC, 17 %) and crustal elements (13 %). Sulphate accounted\ud for 7% of PM2.5 and the sum of other trace elements\ud was 10%. In the RA tunnel, PM2.5 was on average\ud 233 μgm−3, mostly composed of EC (52 %) and OM\ud (39 %). Sulphate, crustal and the trace elements showed a\ud minor contribution with 5 %, 1 %, and 1 %, respectively. The\ud average OC: EC ratio in the JQ tunnel was 1.59±0.09, indicating\ud an important contribution of EC despite the high\ud ethanol fraction in the fuel composition. In the RA tunnel,\ud the OC: EC ratio was 0.49±0.12, consistent with previous\ud measurements of diesel-fuelled HDVs. Besides bulk carbonaceous\ud aerosol measurement, polycyclic aromatic hydrocarbons\ud (PAHs) were quantified. The sum of the PAHs concentration\ud was 56±5 ngm−3 and 45±9 ngm−3 in the RA\ud and JQ tunnel, respectively. In the JQ tunnel, benzo(a)pyrene\ud (BaP) ranged from 0.9 to 6.7 ngm−3 (0.02–0. 1‰of PM2.5)\ud whereas in the RA tunnel BaP ranged from 0.9 to 4.9 ngm−3\ud (0.004–0. 02‰ of PM2.5), indicating an important relative\ud contribution of LDVs emission to atmospheric BaP.\ud Real-time measurements performed in both tunnels provided\ud aerosol size distributions and optical properties. The\ud average particle count yielded 73 000 cm−3 in the JQ tunnel\ud and 366 000 cm−3 in the RA tunnel, with an average diameter\ud of 48 nm in the former and 39 nm in the latter. Aerosol single\ud scattering albedo, calculated from scattering and absorption\ud observations in the JQ tunnel, indicates a value of 0.5 associated\ud with LDVs. Such single scattering albedo is 20–50%\ud higher than observed in previous tunnel studies, possibly as a\ud result of the large biofuel usage. Given the exceedingly high\ud equivalent black carbon loadings in the RA tunnel, real time\ud light absorption measurements were possible only in the JQ\ud tunnel. Nevertheless, using EC measured from the filters, a\ud single scattering albedo of 0.31 for the RA tunnel has been\ud estimated. The results presented here characterise particulate\ud matter emitted from nearly 1 million vehicles fuelled with a\ud considerable amount of biofuel, providing a unique experimental\ud site worldwideFAPESP - 2008/58104-8CNPq - 402383/2009-

Intercomparison of air quality models in a megacity: Towards an operational ensemble forecasting system for São Paulo

An intercomparison of four air quality models is performed in the tropical megacity of Sao Paulo with the perspective of developing an air quality forecasting system based on a regional model ensemble. During three contrasting periods marked by different types of pollution events, we analyze the concentrations of the main regulated pollutants (Ozone, CO, SO2, NOx, PM2.5 and PM10) compared to observations of a dense air quality monitoring network. The modeled concentrations of CO, PM and NOx are in good agreement with the observations for the temporal variability and the range of variation. However, the transport of pollutants due to biomass burning pollution events can strongly affect the air quality in the metropolitan area of Sao Paulo with increases of CO, PM2.5 and PM10, and is associated with an important inter-model variability. Our results show that each model has periods and pollutants for which it has the best agreement. The observed day-to-day variability of ozone concentration is well reproduced by the models, as well as the average diurnal cycle in terms of timing. Overall the performance for ozone of the median of the regional model ensemble is the best in terms of time and magnitude because it takes advantage of the capabilities of each model. Therefore, an ensemble prediction of regional models is promising for an operational air quality forecasting system for the megacity of Sao Paulo.This article is a direct contribution to the research themes of the Klimapolis Lab-836 oratory (klimapolis.net), which is funded by the German Federal Ministry of Education837 and Research (BMBF)

New directions: From biofuels to wood stoves: The modern and ancient air quality challenges in the megacity of São Paulo

A megacity typically refers to a metropolitan area with more than 10 million people. The number of megacities worldwide has increased from 8 in 1970 to 34 in 2016 with their total population exceeding 650 million (City Population, 2016). Air pollution, a consequence of increased population and urbanisation, is a common concern in megacities. Here we focus on the Metropolitan Area of São Paulo (MASP), which is the 5th most populous urban region in the world and the second most populated region in Latin America (UN, 2014), making up ~10% of the total population of Brazil. With 21 million inhabitants and 8511 km2 area (Fig. 1a), the MASP includes 38 metropolitan areas surrounding the city of São Paulo that has a population of 12 million (IBGE, 2016). What makes São Paulo distinctly different from all other megacities in the world is that its vehicle fleet operates exclusively on biofuel blends (sugarcane ethanol and soya diesel) in diesel, making it a unique biofuel-driven megacity. Yet, São Paulo’s air quality face challenges to meet its national standards, which are relatively relaxed compared with the megacities of Asia (e.g., Delhi) or Europe (e.g., London). While the events of highly elevated concentrations of particulate matter (PM) are similarly common as in other megacities, the underlining factors responsible for them are unique to São Paulo and the questions are: - (i) how can the air quality be improved considering that numerous interventions have already been taken in controlling emissions from vehicular fleet? - (ii) how can the transportation system be transformed to make it emission-neutral? - (iii) how the emissions from the main emitters such as the diesel trucks and buses can be reduced? and; - (iv) how the changes in the content of biofuel in diesel have influenced the exceedances and ozone formation? The aim of this paper is to propose answers to the above questions in the context of distinctness in the vehicle fleet, hitherto overlooked sources, underlining causes for pollution exceedances, and to suggest future directions and research needs to better understand and manage air quality of this unique megacity