Os efeitos causados pela presença de áreas urbanizadas da Região Metropolitana de São Paulo (RMSP), conhecidos por ilha de calor urbana, são estudados através da modelagem numérica e da análise de alguns dados observacionais, coletados no período de inverno de 1999 durante a 1ª Fase intensiva de medidas de campo do Projeto Temático FAPESP “Meteorologia e Poluição do Ar em São Paulo” e da rede automática da CETESB. Através da utilização de imagens do satélite LANDSAT-5, foi obtido um arquivo de ocupação do solo na RMSP numa resolução de aproximadamente 424 m. Foram definidos dois tipos de ocupação urbana que diferem principalmente na verticalização e espaçamento entre as construções. Simulações realizadas com uma parametrização adequada ao tratamento das propriedades da superfície em áreas urbanas, o modelo RAMS-TEB, mostraram que as fontes antropogênicas de calor de origem veicular são de grande importância no ciclo diurno de temperatura e umidade na RMSP. Uma comparação entre os dados simulados pelo modelo e dados observacionais de superfície apresentou coeficientes de correlações superiores a 0,9 para a temperatura e superiores a 0,8 para a umidade relativa. A interação entre a brisa marítima e a ilha de calor intensifica as zonas de convergência no centro da cidade, podendo ocasionar a re-circulação de poluentes nessa região. Simulações sobre o efeito da urbanização mostram que a ilha de calor urbana faz com que haja uma propagação mais rápida da frente de brisa até o centro da RMSP, que permanece estacionária por algum tempo nessa região. Os efeitos da topografia mostraram-se fundamentais na intensidade da brisa marítima e sua propagação sobre o continente. A presença de grandes corpos d’água, tais como a represa de Guarapiranga e Billings, contribui para a diminuição das amplitudes do ciclo diurno de temperatura na RMSP através das circulações do tipo brisa lacustre geradas pelos mesmos. O uso de um modelo de dispersão mostrou que, com a propagação da frente de brisa para o interior (na direção SE-NW), poluentes emitidos na RMSP são transportados para áreas remotas, diminuindo a concentração dos mesmos nas regiões emissoras. / The effects caused by urbanization in the Metropolitan Area of São Paulo (MASP), known as urban heat island, are studied through the use of numerical modeling and some observed data, collected in the 1999’s winter time during the first phase of intensive field measurements from the Thematic Project FAPESP “Meteorology and Air Pollution in São Paulo” and also from CETESB automatic network. A 424 m resolution land use file was created using LANDSAT-5 satellite pictures where two different kinds of urban regions were identified. The main differences between these regions are the vertical structure and spacing between buildings. Simulations performed with an appropriate parameterization for the treatment of surface properties in urban areas showed that anthropogenic sources due to traffic are of great importance to the temperature and humidity diurnal cycle in MASP. Comparisons between simulated and observed surface data had a correlation coefficient greater than 0.9 for temperature and greater than 0.8 for relative humidity. The interaction between the see breeze and the urban heat island intensify the convergence zones in the center of the city, eventually causing the re-circulation of pollutants in this region. Simulations of the urbanization effects showed that the urban heat island is responsible for a faster propagation of the sea breeze front up to the center of the MASP, remaining stationary in this region for some time. The topographic effects are fundamental in the intensity of the sea breeze and its inland propagation. The presence of large water bodies, as the Guarapiranga and Billings Dams, contribute to a decrease in the temperature diurnal cycle amplitudes because of the lake breeze circulations generated by them. The use of a simple dispersion model showed that with the propagation of the sea breeze front to the countryside (in the direction SE-NW), pollutants emitted in MASP are transported to remote areas, causing a decrease in the concentration of these pollutants in the source region.

This research paper was submitted to the Department of Geography in fulfilment of the requirements of Geography 4C6. / This research details the presence of the land/ sea breeze circulation system near Churchill, Manitoba. Data collected from June 6 to August 13, 1987 were analyzed with respect to wind direction, temperature and vapour pressure to determine the effects of the system on the climate. Results indicate that there is a seasonal progression in wind frequency from dominantly onshore (42% of the time) to dominantly mixed winds (75% of the time). The frequency of the land/ sea breeze increases across the season. Smaller wind velocities, colder temperatures and larger vapour pressures are associated with onshore winds, while offshore winds have greater velocities, higher temperatures, and smaller vapour pressures. Offshore winds are 5-7°C warmer than onshore winds. The sea breeze is larger than the land breeze by a 3:2 ratio. / Thesis / Bachelor of Arts (BA)

Eventos de brisa marítima (BM) são comuns na Região Metropolitana de São Paulo (RMSP). No verão, em particular, estão associados com tempestades, chuvas, rajadas de vento, granizo e descargas atmosféricas intensas na RMSP. Utilizou-se o método de OLIVEIRA e SILVA DIAS (1982) para identificar os eventos de BM. Todos os eventos de BM entre 2005 e 2008 foram analisados por meio de medições de superfície, altitude, radares meteorológicos, satélite e modelagem numérica da atmosfera. Em geral, a penetração da frente de BM na RMSP ocorre entre o meio e o fim da tarde com aumento da temperatura do ponto de orvalho. Ainda, o ambiente urbano mais aquecido tende a intensificar as tempestades que podem produzir enchentes, alagamentos, queda de árvores, entre outros impactos socioeconômicos muito significativos. A partição anual pluviométrica devido a BM foi estimado com o radar meteorológico de São Paulo. Os resultados indicam um núcleo de máxima precipitação acumulada com pico de 600 mm sobre a RMSP, muito maior que no entorno dessa. A modelagem com o ARPS permitiu simular condições médias espaciais em baixos, médios e altos níveis de diversas variáveis dos eventos analisados. As simulações de controle e específicas com ARPS sugerem um impacto significativo da cobertura do solo na distribuição espacial da precipitação. As análises foram complementadas com medições do radar meteorológico MXPOL e demonstram a importância desse tipo de sensoriamento remoto na detecção e previsão a curtíssimo prazo da penetração de BM, com alta resolução espaço-temporal. / Sea breeze events (SB) are common in Metropolitan area at São Paulo (MASP). Particularly, in the summer, SB triggers over MASP deep convection, heavy rainfall, wind gusts, hail and lightning. OLIVEIRA and SILVA DIAS (1982) method was used to identify the SB events. SB events between 2005 and 2008 were analysed by means of surface and upper air measurements, weather radar, satellite and numerical modelling. In general, the SB front penetrates in MASP between midafternoon and evening increasing dew point. Moreover, the warmer urban environment tends to intensify storms that produce flooding, falling trees, among other large socioeconomic impacts. The annual rainfall partition due to SB was estimated using the São Paulo weather radar. The results indicate a core of maximum rainfall accumulation of 600 mm over MASP, much larger than that in the vicinity. The modelling with ARPS allowed simulate conditions spatial average in low, medium and upper levels of several variables of the analysed events. Moreover, the ARPS system was used to simulate SB with control and specific runs. Results suggest significant impact of surface cover on rainfall distribution. MXPOL weather radar measurements of SB were important in detecting and nowcasting SB inflow at very high spatial and temporal resolution.

A Região Metropolitana de São Paulo (RMSP) conta com mais de 20 milhões de habitantes em 7958 km², o que a caracteriza como uma megacidade. Este fato ocasiona o efeito de ilha de calor que pode resultar em interações complexas com circulações de mesoescala, tais como a brisa marítima, podendo influenciar nos padrões de circulação local e afetar diretamente o tempo e o clima da região. Dessa forma, através da modelagem numérica com o modelo de mesoescala WRF este trabalho se propôs a analisar e avaliar os possíveis efeitos da expansão da mancha urbana - passada e futura - na modificação destes padrões em duas estações do ano de 2007: inverno (18/08) e verão (07/03). Para isto introduziu-se diferentes manchas urbanas no modelo, supondo nenhuma urbanização, urbanização observada em 1952 e em 2007, bem como uma suposta urbanização prevista para o ano de 2030. O acoplamento de um modelo de dossel urbano junto ao WRF também foi avaliado, e os resultados mostraram que para o inverno a inclusão do mesmo se mostrou dispensável, enquanto para o verão as simulações em que o módulo esteve ativo se mostraram mais coerentes à realidade. Para as duas estações observou-se a influência da expansão da mancha urbana nos eventos de brisa marítima, sendo que quanto maior a área urbanizada maior o tempo de deslocamento da frente de brisa continente adentro, podendo a diferença chegar a 2 horas. Diferenças na temperatura também puderam ser vistas, principalmente à noite no período de inverno, de forma que algumas regiões chegaram a apresentar 6 °C a mais em 2007. Observou- se uma frente de umidade acompanhando a frente de brisa marítima e quanto maior a urbanização, menor a quantidade de umidade associada, chegando a uma redução de 22% durante o inverno e de 33% durante o verão. No inverno não foram observadas grandes diferenças na precipitação, enquanto que no verão foram encontradas diferenças significativas em praticamente todo o domínio de simulação, chegando a 50 mm em determinadas regiões (a mais ou a menos). Tais diferenças na precipitação não se mostraram lineares com a expansão da mancha urbana. Cortes verticais não evidenciaram circulações bem definidas associadas à ilha de calor, nem para o inverno nem para o verão, no entanto, claramente pôde-se observar a influência que a expansão urbana tem sobre os episódios de brisa marítima, em quaisquer das variáveis meteorológicas analisadas. / The Metropolitan Area of São Paulo (MASP) has over 20 million inhabitants over a 7958 km² area, which characterizes a megacity. This fact causes the heat island effect that can result in complex interactions with mesoscale circulations such as the sea breeze and can influence the local circulation and directly affect the weather and climate of the region. Therefore, through numerical modeling of the atmosphere using the WRF mesoscale model this work analyses and evaluates the possible effects of urban expansion - past and future on the modification of these patterns in two days representatives of the winter and summer (18/08 and 07/03, respectively). For that purpose we introduced different types of urban areas in the model, assuming no urbanization, using the urbanization observed in 1952 and 2007 as well as a hypothetical urbanization numerically predicted for the year of 2030. The coupling of an urban canopy model (UCM) along with WRF was also evaluated and the results showed that the inclusion of UCM proved to be unnecessary during wintertime. However, in the summer, the simulations where the module was activated were more consistent with reality. For the two seasons we observed the influence of urban expansion in the events of sea breeze, and the higher the urbanized area more increased was the travel time of the sea breeze front inland, being the time difference as high as 2 hours. Differences in temperature were also observed, especially at night in the winter, so that some regions were as high as 6 °C hotter in 2007. A moisture front accompanying the sea breeze front and the higher the urbanization the lower the amount of moisture associated, reaching a reduction of 22% during winter and 33% during the summer. During the winter no major differences were observed in precipitation, while in the summer significant differences were found almost over all simulation domain, reaching 50 mm in certain regions (positive or negative). Such differences in precipitation were not linear with the expansion of urban area. Vertical sections did not show well-defined circulations associated with urban heat island, neither for the winter nor for summer, however, we can clearly observe the influence that urban area extension has on episodes of sea breeze in any of the weather variables.

<p>Three different studies have been made; an analysis of the general weather situation at three weather stations in Svalbard, close to the main settlement Longyearbyen; an instrumental comparison between three weather stations operating at nearly the same place during a few days in October 2006; and a case study of a weather station at the mountain Breinosa compared to the station in the valley beneath.</p><p>The analysis of the general weather at the three stations, Adventdalen (data used from 2004-2006), Svalbard Airport (data used from 1994-2004) and Gruvefjellet (data used from 2002-2005) showed that it is clear that the local surroundings do contribute to a more locally produced weather. The mean wind speed in Adventdalen was shown to be 5.1 m/s and the wind direction was mostly from inland towards the coast. Channelling effects dominates the winds in the valley, resulting in high wind speeds. The channelled winds from Adventdalen often reach Svalbard Airport (average wind speed 4.8 m/s). At the Airport there is also a contribution of winds (mostly in summer) originating from the sea, e.g. sea breeze. In times when the weather at Svalbard Airport was more continental, Adventfjorden and Isfjorden were likely to be covered by ice. The higher location of Gruvefjellet most often contributes to low temperatures and an average wind speed of 3.9 m/s. However, the temperature at Adventdalen and the Airport are often colder than at Gruvefjellet due to the frequency of temperature inversions.</p><p>The instrumental comparison concerned three stations in Adventdalen. Data from the stationary weather station was compared with data from two temporarily stations during 4-7th October 2006. It is apparent that the stationary station needs calibration, at least when looking at the pressure measurements, where there clearly is an offset in the data.</p><p>The third study was a case study concerned data from a station at the mountain Breinosa and Adventdalen. A new weather station will be put up during 2007 and data (16th December 2005 until 12th January 2006) from a temporarily station was used when determining the differences from the station down in the valley (Adventdalen). The wind speed is often just as high in the valley as at Breinosa due to channelling effects. The temperature in Adventdalen seems to be affected by the temperature at Breinosa. The air is chilled and sinks down to be channelled through the valley. There are some occasions when the temperature at the mountain is higher than beneath. During those events the wind speed is low and a temperature inversion develops at the ground.</p> / <p>Tre olika studier genomförts; en analysering av data från tre väderstationer på Svalbard;en instrumentell jämförelse mellan tre väderstationer på Svalbard nära huvudorten Longyearbyen; en fallstudie av data från en väderstation på berget Breinosa jämfört med situationen i Adventdalen nedanför.</p><p>Undersökningen av generella vädersituationen vid de tre stationerna, Adventdalen (data från 2004-2006), Svalbard Flygplats (data från 1994-2004) och Gruvefjellet (data från 2002-2005) visade tydligt att den lokala omgivningen bidrar mycket till hur vädret formas. Medelvindhastigheten i Adventdalen var 5,1 m/s och vindriktningen mestadels längs dalen ut mot fjorden. Kanaliseringseffekter dominerar vindarna i dalen och bidrar till de höga vindhastigheterna. Kanaliserade vindar från Adventdalen når ofta Svalbard Flygplats (medel vindhastighet 4,8 m/s). Vid Flygplatsen finns också ett visst bidrag från vindar utifrån havet (mestadels under sommaren), d.v.s. sjöbris. I situationer då vädret vid flygplatsen varit mer kontinentalt så har Adventfjorden mest troligt varit täckt av is.</p><p>Gruvefjellets höga placering bidrar till låga temperaturer och en medelvindhastighet på 3.9 m/s. Dock är temperaturen är ofta lägre i Adventdalen och vid Flygplatsen på grund av att det ofta förekommer temperaturinversioner i marknivå.</p><p>Den instrumentella jämförelsen berörde tre stationer i Adventdalen. Data från den stationära stationen jämfördes under 4-7 oktober 2006 med data från två temporära stationer. Det är tydligt att den stationära stationen är i behov av kalibrering. I alla fall är det uppenbart vid studien av lufttrycket som tydligt är förskjutet och visar ett lägre tryck.</p><p>Tredje studien var en fallstudie och data undersöktes från berget Breinosa och Adventdalen. En ny väderstation kommer att monteras på Breinosa under 2007 och data (16 december 2005 till 12 januari 2006) från en temporär station användes i studien. Vindhastigheten är ofta lika hög i dalen som på berget på grund av kanaliseringseffekter. Temperaturen i dalen förefaller vara påverkad av temperatursituationen på berget. Avkyld luft sjunker och kanaliseras ner i dalen. Det finns några tillfällen då temperaturen på berget Breinosa är högre än nere i dalen. Under de situationerna avtar vindhastigheten och en temperaturinversion bildas i marknivå.</p>

Three different studies have been made; an analysis of the general weather situation at three weather stations in Svalbard, close to the main settlement Longyearbyen; an instrumental comparison between three weather stations operating at nearly the same place during a few days in October 2006; and a case study of a weather station at the mountain Breinosa compared to the station in the valley beneath. The analysis of the general weather at the three stations, Adventdalen (data used from 2004-2006), Svalbard Airport (data used from 1994-2004) and Gruvefjellet (data used from 2002-2005) showed that it is clear that the local surroundings do contribute to a more locally produced weather. The mean wind speed in Adventdalen was shown to be 5.1 m/s and the wind direction was mostly from inland towards the coast. Channelling effects dominates the winds in the valley, resulting in high wind speeds. The channelled winds from Adventdalen often reach Svalbard Airport (average wind speed 4.8 m/s). At the Airport there is also a contribution of winds (mostly in summer) originating from the sea, e.g. sea breeze. In times when the weather at Svalbard Airport was more continental, Adventfjorden and Isfjorden were likely to be covered by ice. The higher location of Gruvefjellet most often contributes to low temperatures and an average wind speed of 3.9 m/s. However, the temperature at Adventdalen and the Airport are often colder than at Gruvefjellet due to the frequency of temperature inversions. The instrumental comparison concerned three stations in Adventdalen. Data from the stationary weather station was compared with data from two temporarily stations during 4-7th October 2006. It is apparent that the stationary station needs calibration, at least when looking at the pressure measurements, where there clearly is an offset in the data. The third study was a case study concerned data from a station at the mountain Breinosa and Adventdalen. A new weather station will be put up during 2007 and data (16th December 2005 until 12th January 2006) from a temporarily station was used when determining the differences from the station down in the valley (Adventdalen). The wind speed is often just as high in the valley as at Breinosa due to channelling effects. The temperature in Adventdalen seems to be affected by the temperature at Breinosa. The air is chilled and sinks down to be channelled through the valley. There are some occasions when the temperature at the mountain is higher than beneath. During those events the wind speed is low and a temperature inversion develops at the ground. / Tre olika studier genomförts; en analysering av data från tre väderstationer på Svalbard;en instrumentell jämförelse mellan tre väderstationer på Svalbard nära huvudorten Longyearbyen; en fallstudie av data från en väderstation på berget Breinosa jämfört med situationen i Adventdalen nedanför. Undersökningen av generella vädersituationen vid de tre stationerna, Adventdalen (data från 2004-2006), Svalbard Flygplats (data från 1994-2004) och Gruvefjellet (data från 2002-2005) visade tydligt att den lokala omgivningen bidrar mycket till hur vädret formas. Medelvindhastigheten i Adventdalen var 5,1 m/s och vindriktningen mestadels längs dalen ut mot fjorden. Kanaliseringseffekter dominerar vindarna i dalen och bidrar till de höga vindhastigheterna. Kanaliserade vindar från Adventdalen når ofta Svalbard Flygplats (medel vindhastighet 4,8 m/s). Vid Flygplatsen finns också ett visst bidrag från vindar utifrån havet (mestadels under sommaren), d.v.s. sjöbris. I situationer då vädret vid flygplatsen varit mer kontinentalt så har Adventfjorden mest troligt varit täckt av is. Gruvefjellets höga placering bidrar till låga temperaturer och en medelvindhastighet på 3.9 m/s. Dock är temperaturen är ofta lägre i Adventdalen och vid Flygplatsen på grund av att det ofta förekommer temperaturinversioner i marknivå. Den instrumentella jämförelsen berörde tre stationer i Adventdalen. Data från den stationära stationen jämfördes under 4-7 oktober 2006 med data från två temporära stationer. Det är tydligt att den stationära stationen är i behov av kalibrering. I alla fall är det uppenbart vid studien av lufttrycket som tydligt är förskjutet och visar ett lägre tryck. Tredje studien var en fallstudie och data undersöktes från berget Breinosa och Adventdalen. En ny väderstation kommer att monteras på Breinosa under 2007 och data (16 december 2005 till 12 januari 2006) från en temporär station användes i studien. Vindhastigheten är ofta lika hög i dalen som på berget på grund av kanaliseringseffekter. Temperaturen i dalen förefaller vara påverkad av temperatursituationen på berget. Avkyld luft sjunker och kanaliseras ner i dalen. Det finns några tillfällen då temperaturen på berget Breinosa är högre än nere i dalen. Under de situationerna avtar vindhastigheten och en temperaturinversion bildas i marknivå.

Methane measurements over lake Tämnaren show a pronounced diurnal variation with high values at night and low values during daytime. The atmosphere over the lake and its surroundings is simulated with two different settings and resolutions of the WRF model during a period of eight days in May 2011 to investigate if a lake/land breeze circulation could be the cause of the observed methane variation. A night time land breeze can give rise to convergence over Tämnaren of the natural methane emissions from the lake which possibly could explain the diurnal variation. Analysis show that although Tämnaren is large enough to initiate a fully closed circulation these events are likely going to be rare because of the strong dependence of the background wind speed and cannot therefore be the cause of the pronounced diurnal variation. A fairly moderate wind speed will dominate over the thermodynamical forcing necessary to create a lake breeze. Even so, it is possible that a closed or nearly closed circulation could enhance the diurnal pattern with an increase of methane concentration at night and a decrease during the day. The reason for the high night time methane concentration is more likely due to the accumulation in a shallow internal boundary layer that develops over the lake combined with high night time methane flux caused by waterside convection. / Mätningar av metankoncentrationen över Tämnaren visar en tydlig dygnsvariation med höga värden på natten och låga under dagtid. Atmosfären över sjön med omgivning modelleras med två olika inställningar och upplösningar av WRF modellen under en åttadagarsperiod i Maj 2011 för att undersöka om en sjö- och landbriscirkulation kan vara orsaken till den observerade metanvariationen. På natten kan en landbris ge upphov till konvergens över Tämnaren av de naturliga metanutsläppen vilket skulle kunna vara en möjlig förklaring till dygnsvariationen. Vidare analys visar att Tämnaren är tillräckligt stor för att initiera en sluten cirkulation men dessa händelser är troligtvis sällsynta på grund av det starka inflytandet av bakgrundsvinden och kan därför inte vara orsaken till den uttalade metanvariationen. En relativt måttlig vind kommer dominera över den termodynamiska effekt som är drivande för skapandet av sjö- och landbris. Trots detta är det möjligt att en sluten eller nästan sluten cirkulation kan förstärka metanhaltens dygnsvariation med en ökning på natten och minskning under dagen. Orsaken till den observerade höga metankoncentrationen på natten är troligare en ackumulering i ett grunt internt ytskikt som bildas över Tämnaren kombinerat med höga nattliga metanflöden till följd av konvektion i sjön.

A Região Metropolitana de São Paulo (RMSP) conta com mais de 20 milhões de habitantes em 7958 km², o que a caracteriza como uma megacidade. Este fato ocasiona o efeito de ilha de calor que pode resultar em interações complexas com circulações de mesoescala, tais como a brisa marítima, podendo influenciar nos padrões de circulação local e afetar diretamente o tempo e o clima da região. Dessa forma, através da modelagem numérica com o modelo de mesoescala WRF este trabalho se propôs a analisar e avaliar os possíveis efeitos da expansão da mancha urbana - passada e futura - na modificação destes padrões em duas estações do ano de 2007: inverno (18/08) e verão (07/03). Para isto introduziu-se diferentes manchas urbanas no modelo, supondo nenhuma urbanização, urbanização observada em 1952 e em 2007, bem como uma suposta urbanização prevista para o ano de 2030. O acoplamento de um modelo de dossel urbano junto ao WRF também foi avaliado, e os resultados mostraram que para o inverno a inclusão do mesmo se mostrou dispensável, enquanto para o verão as simulações em que o módulo esteve ativo se mostraram mais coerentes à realidade. Para as duas estações observou-se a influência da expansão da mancha urbana nos eventos de brisa marítima, sendo que quanto maior a área urbanizada maior o tempo de deslocamento da frente de brisa continente adentro, podendo a diferença chegar a 2 horas. Diferenças na temperatura também puderam ser vistas, principalmente à noite no período de inverno, de forma que algumas regiões chegaram a apresentar 6 °C a mais em 2007. Observou- se uma frente de umidade acompanhando a frente de brisa marítima e quanto maior a urbanização, menor a quantidade de umidade associada, chegando a uma redução de 22% durante o inverno e de 33% durante o verão. No inverno não foram observadas grandes diferenças na precipitação, enquanto que no verão foram encontradas diferenças significativas em praticamente todo o domínio de simulação, chegando a 50 mm em determinadas regiões (a mais ou a menos). Tais diferenças na precipitação não se mostraram lineares com a expansão da mancha urbana. Cortes verticais não evidenciaram circulações bem definidas associadas à ilha de calor, nem para o inverno nem para o verão, no entanto, claramente pôde-se observar a influência que a expansão urbana tem sobre os episódios de brisa marítima, em quaisquer das variáveis meteorológicas analisadas. / The Metropolitan Area of São Paulo (MASP) has over 20 million inhabitants over a 7958 km² area, which characterizes a megacity. This fact causes the heat island effect that can result in complex interactions with mesoscale circulations such as the sea breeze and can influence the local circulation and directly affect the weather and climate of the region. Therefore, through numerical modeling of the atmosphere using the WRF mesoscale model this work analyses and evaluates the possible effects of urban expansion - past and future on the modification of these patterns in two days representatives of the winter and summer (18/08 and 07/03, respectively). For that purpose we introduced different types of urban areas in the model, assuming no urbanization, using the urbanization observed in 1952 and 2007 as well as a hypothetical urbanization numerically predicted for the year of 2030. The coupling of an urban canopy model (UCM) along with WRF was also evaluated and the results showed that the inclusion of UCM proved to be unnecessary during wintertime. However, in the summer, the simulations where the module was activated were more consistent with reality. For the two seasons we observed the influence of urban expansion in the events of sea breeze, and the higher the urbanized area more increased was the travel time of the sea breeze front inland, being the time difference as high as 2 hours. Differences in temperature were also observed, especially at night in the winter, so that some regions were as high as 6 °C hotter in 2007. A moisture front accompanying the sea breeze front and the higher the urbanization the lower the amount of moisture associated, reaching a reduction of 22% during winter and 33% during the summer. During the winter no major differences were observed in precipitation, while in the summer significant differences were found almost over all simulation domain, reaching 50 mm in certain regions (positive or negative). Such differences in precipitation were not linear with the expansion of urban area. Vertical sections did not show well-defined circulations associated with urban heat island, neither for the winter nor for summer, however, we can clearly observe the influence that urban area extension has on episodes of sea breeze in any of the weather variables.

Eventos de brisa marítima (BM) são comuns na Região Metropolitana de São Paulo (RMSP). No verão, em particular, estão associados com tempestades, chuvas, rajadas de vento, granizo e descargas atmosféricas intensas na RMSP. Utilizou-se o método de OLIVEIRA e SILVA DIAS (1982) para identificar os eventos de BM. Todos os eventos de BM entre 2005 e 2008 foram analisados por meio de medições de superfície, altitude, radares meteorológicos, satélite e modelagem numérica da atmosfera. Em geral, a penetração da frente de BM na RMSP ocorre entre o meio e o fim da tarde com aumento da temperatura do ponto de orvalho. Ainda, o ambiente urbano mais aquecido tende a intensificar as tempestades que podem produzir enchentes, alagamentos, queda de árvores, entre outros impactos socioeconômicos muito significativos. A partição anual pluviométrica devido a BM foi estimado com o radar meteorológico de São Paulo. Os resultados indicam um núcleo de máxima precipitação acumulada com pico de 600 mm sobre a RMSP, muito maior que no entorno dessa. A modelagem com o ARPS permitiu simular condições médias espaciais em baixos, médios e altos níveis de diversas variáveis dos eventos analisados. As simulações de controle e específicas com ARPS sugerem um impacto significativo da cobertura do solo na distribuição espacial da precipitação. As análises foram complementadas com medições do radar meteorológico MXPOL e demonstram a importância desse tipo de sensoriamento remoto na detecção e previsão a curtíssimo prazo da penetração de BM, com alta resolução espaço-temporal. / Sea breeze events (SB) are common in Metropolitan area at São Paulo (MASP). Particularly, in the summer, SB triggers over MASP deep convection, heavy rainfall, wind gusts, hail and lightning. OLIVEIRA and SILVA DIAS (1982) method was used to identify the SB events. SB events between 2005 and 2008 were analysed by means of surface and upper air measurements, weather radar, satellite and numerical modelling. In general, the SB front penetrates in MASP between midafternoon and evening increasing dew point. Moreover, the warmer urban environment tends to intensify storms that produce flooding, falling trees, among other large socioeconomic impacts. The annual rainfall partition due to SB was estimated using the São Paulo weather radar. The results indicate a core of maximum rainfall accumulation of 600 mm over MASP, much larger than that in the vicinity. The modelling with ARPS allowed simulate conditions spatial average in low, medium and upper levels of several variables of the analysed events. Moreover, the ARPS system was used to simulate SB with control and specific runs. Results suggest significant impact of surface cover on rainfall distribution. MXPOL weather radar measurements of SB were important in detecting and nowcasting SB inflow at very high spatial and temporal resolution.

Longshore sediment transport rate was measured during energetic sea breeze activity, on intermediate-to-reflective sandy beaches in Southwestern Australia. Estimates of suspended load were obtained using backscatter sensors, current meters and streamer traps. Total load was determined using fluorescent tracer sand and an impoundment study. The measurementsw ere cross-compareda nd usedt o evaluates everalw idely-used longshore transport equations. The streamer trap measurement revealed an exponential distribution of the suspended sediment flux with vertical mixing decreasing in the onshore direction. A continuous time series of the longshore suspended sediment flux across the surf zone was obtained by combining the streamer trap measurements with data collected using surf zone instruments. Comparison of the suspended longshore flux with the total longshore flux derived from the dispersal of the sand tracer indicated that the relative contribution of the suspendedlo ad to the total load was at least 59 %. The movement of sandt racer on four different beaches demonstrated that nearshore sediments were transported obliquely across the surf zone, challenging our conventional view of dividing nearshore sediment transport into cross-shore and longshore components. Furthermore, tracer was found to move from the outer surf zone to the swash zone and vice versa, indicating a cross-shore sediment exchange. The contribution of the swash zone to the total longshore flux was estimated around 30-40 %. Despite large differences in the temporal and spatial scales of the measurement techniques, the littoral drift rates are comparable, suggesting a northward transport rate of 138,000-200,000 m3 year-1. Longshore sediment transport during sea breezes is mainly the result of a high longshore energy flux exerted by wind waves. This is accurately predicted by the equations of Inman and Bagnold (1963) and CERC (1984). The bimodal wave field, characteristic of Southwestern Australia, renders the Kamphuis (1991b) formula unsuitable in this instance.