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The present study provides a synoptic characterization of South Atlantic Convergence Zone (SACZ) episodes that caused heavy rainfall events (HRE) in the city of Rio de Janeiro (CRJ) between 2006 and 2016. A total of 77 SACZ episodes were identified in the CRJ (SCRJ), which represented 81% of the total SACZ events in Brazil. At least one day of HRE during the SACZ period (SHRE) was found in 37 SCRJ episodes, representing almost half (48%) of the SACZ events in the CRJ. In 68.6% of these cases, the heavy rainfall occurred on the first two days of the SHRE period. The mean synoptic pattern of SHRE showed a cold front in the Atlantic Ocean connected with a low-pressure system located near the coast of Rio de Janeiro state (RJ). The 850 hPa specific humidity showed a dipole pattern with positive anomalies in southeastern Brazil and negative anomalies in southern Brazil since the day before the occurrence of SHRE. An anomalous upper-level ridge in southeastern Brazil was relevant to intensifying the heavy rainfall in the CRJ. The synoptic classification showed four main surface synoptic patterns associated with SHRE. The two most frequent patterns were associated with a cold front close to the coast of RJ, and the other two were related to the presence of an anticyclone with blocking characteristics and to the presence of a weak extratropical cyclone near the coast of RJ.

This work aimed to identify the synoptic conditions associated with the Frontal Systems (FSs) passage that causes intense winds in the Santos Basin (SB). Furthermore, the atmospheric characteristics of the FSs, which generated intense (INTW) and moderate (MODW) winds in the studied area were identified. For this purpose, INTW and MODW composites of FSs episodes were elaborated. First, the INTW and MODW cases were selected from the 10 meters wind intensity (W10M) observed in the Santos buoy, belonging to Brazil's National Buoys Program. Satellite images and synoptic surface charts were analyzed to identify the synoptic systems responsible for INTW and MODW in the Santos buoy, keeping only the cases generated by FSs. From the comparison between the INTW and MODW composites, it was possible to observe in INTW: i) a stronger pressure gradient over the SB, which caused the intense winds registered in the buoy; ii) a baroclinic trough at medium and high levels reaching the SB region, and located westward of the surface system; iii) stronger 1000-500 hPa layer thickness and dew point temperature gradients over the continent, reaching the SB region, indicating the position of the FS and iv) a colder and drier air mass over southern Brazil. In large scale, the Rossby wave tracings were analyzed, where different wavenumbers were noticed for each composite. In INTW, the wavenumber was 2, while in MODW, it was 2 and 3. For case studies of INTW and MODW, the main characteristics found in the respective composites were observed.

Climate change can affect directly the hydrological cycle and influence groundwater availability due to the direct or indirect impact on recharge and discharge processes. The present investigation focuses on groundwater recharge processes in a fluvial-deltaic aquifer in the northern part of the Rio de Janeiro state (Brazil), a region that relies on groundwater resources and where meteorological data indicate a shift from tropical humid climatic conditions to semiarid. The main objective is to understand how groundwater resources respond to the consequences of climate change on groundwater recharge, in order to improve groundwater management practices and guarantee quantitative and qualitative good status. Climate models’ data and projections were used as a tool to provide a better understanding of how climate change can modify the dynamics in the studied groundwater system. The present climate indices for extreme temperature and precipitation (1961–1990) were examined in order to establish the current climatology for the study area, and the Thornthwaite−Mather hydrometeorological balance (TMHB) was used to calculate inputs to the aquifer. Projections for annual rainfall and air temperature for the period 2041–2070 obtained from Eta5km_HadGEM2-ES outputs for the Intergovernmental Panel on Climate Change scenarios RCP4.5 and RCP8.5 were used to estimate recharge to the aquifer using the hydrological code Visual Balan v2.0. Results revealed a tendency to air temperature increase and decrease in precipitation rate for the period of study. Consequently, there was a reduction of recharge in both IPCC scenarios used for the estimation, indicating a decrease in the groundwater resources stored in the region. These results place new challenges to guarantee sustainable groundwater management and the achievement of new aquifer system equilibrium to adapt to climate change impacts.

Sao Tome and Principe is a small insular African country extremely vulnerable to rising sea levels and impacts such as inundation, shore line change, and salt water intrusion into underground aquifers. Projections of climate change have considered coarse model resolutions. The objective of this work is to dynamically downscale the global model projections to 4-km resolution and to assess the climate change in the Sao Tome and Principe islands. The global climate projections are provided by the Canadian Earth System Model under two Representative Concentration Pathways greenhouse gas scenarios, RCP4.5 and RCP8.5. The downscaling is produced by the Eta regional climate model. The baseline period is taken between 1971 and 2000, and the future climate period is taken between 2041 and 2070. The 2-m temperature simulations show good agreement with station data. The model simulates temperature more accurately than precipitation. The precipitation simulations systematically show underestimation and delay of the rainy and the dry seasons by about 1 month, a feature inherited from the global climate model. In the middle of the 21st century, projections show the strongest warming in the elevated parts of the Sao Tome Island, especially in February under RCP8.5. Warmer nights and warmer days become more frequent in the islands when compared with those in the present. While under RCP4.5, precipitation increases in the islands; under RCP8.5, it decreases everywhere in both islands. Heavy precipitation rates should increase, especially in the south-southwestern parts of the Sao Tome islands. Detailed spatial variability of the temperature and precipitation changes in the islands can only be revealed at very high spatial model resolution. Implications for the potential energy production from two major river basins are assessed in this work.

Este trabalho analisa as climatologias da temperatura do ar e da precipitacao da Bacia do rio Paraiba do Sul (BRPS), localizada na Regiao Sudeste do Brasil. A precipitacao anual varia entre 1000 mm no norte do estado do Rio de Janeiro e 2000 mm sobre a Serra da Mantiqueira. Aproximadamente 80% da precipitacao da bacia concentra-se nos meses de outubro a marco, sugerindo um regime monconico na regiao. A media anual da temperatura media diaria varia entre 16°C no extremo sudoeste e 22°C no extremo norte da BRPS. Essa grande variacao se deve a localizacao da BRPS na regiao de transicao entre latitudes medias e tropicais. O efeito da passagem de frentes frias sobre a temperatura e o efeito da atuacao da Zona de Convergencia do Atlântico Sul sobre a precipitacao podem ser observados na distribuicao espacial e temporal das variaveis estudadas.

The main objective of this article is to describe the factors and issues responsible for the evolution of the weather forecast in Brazil.This is done based on a historical review of the formation and evolution of the national meteorological services in the last 170 yearsand on the development of weather forecasting methods. Changes in the routines of weather forecasting services in two centenaryBrazilian institutions, the National Institute of Meteorology and the Brazilian Navy, since the creation of the first subjective forecaststo the present day, are highlighted. Information about the 14 undergraduate courses in Meteorology in Brazil is given, which supportthe technological development of this science, through scientific research and training of human resources. The introduction ofmeteorological radar in the 1970s, and its current networks, as well as the elaboration of the first numerical weather predictions (NWP)by the Center for Weather Forecasting and Climate Studies (Centro de Previsão do Tempo e Estudos Climáticos do Instituto Nacionalde Pesquisas Espaciais – CPTEC/INPE), in 1995, are also described. To complement, a survey is presented, showing the currentworking conditions of weather forecasters. The survey results reveal that 45% of the 102 meteorologists interviewed use the CzechRepublic Windy application to prepare their weather forecasts operationally and almost 60% use the Wyoming University website toobtain data from radiosondes launched in Brazil. It is important to highlight that, since the introduction of NWP by CPTEC/INPE, at theend of the 1990s, there has been a great advance in the field of weather forecasting. Moreover, observational networks have undergonea great expansion, with a significant increase in the number of weather stations in recent decades. Despite all the progress achieved,there is still a need for the integration of observational networks and databases of various institutions. Finally, the development ofapplications that meet the demand of young meteorologists in the operational centers is advisable.

The objective of this work is to describe the climate of Espirito Santo and the northern part of the Campos Basin (i.e., the Espirito Santo geographical area - ESGA), which is located in southeastern Brazil. The observed data from the Floating, Production, Storage and Offloading-Brazil platform, operated by Petrobras during the period 2004-2013, are used in this work. The results show that the 10-m wind over the ESGA blows predominantly from the northeast, north and east directions during the year, with moderate intensity (between 4.0 and 7.0 m s -1 ). The north wind is more intense than the south quadrant wind, which occurs during the passage of the transient systems. The average wind speed depends on the South Atlantic subtropical anticyclone position, which influences the surface pressure gradient over the study area. The wind is weaker during autumn; it reaches a monthly average of 5.3 m s -1 in April and is stronger in September and January (7.3 and 7.1 m s -1 , respectively). The mean sea level pressure oscillates between 1012.3 hPa in the summer and 1019.5 hPa in the winter; the 2-m air temperature varies between 23.2°C in September and 27.4°C in March, and the 2-m relative humidity exhibits a minimum of 72.7% in May and a maximum of 84.2% in December. With regard to the frontal systems frequency, an average of 30.2 systems reach the southern ESGA each year, with a maximum in September (3.9 systems) and a minimum in February (0.8 system).

Neste trabalho elaboram-se analises da variabilidade espacial das tendencias dos indicadores de extremos de precipitacao no estado do Espirito Santo (ES). Alem disso, sao analisadas as climatologias (1971-2010) de indicadores de tais extremos. O objetivo e detectar possiveis mudancas no comportamento da precipitacao, a fim de contribuir com medidas de mitigacao e adaptacao as mudancas climaticas. Para isso sao utilizadas series de chuva diaria, com mais de 40 anos de dados, coletados em 80 postos da Agencia Nacional de Aguas localizados no ES. Os 5 indicadores anuais analisados neste trabalho sao: total pluviometrico (PRCPTOT); percentil 95 da precipitacao diaria (R95p); maxima precipitacao em 5 dias consecutivos (RX5day); numero de dias do ano em que a precipitacao diaria e igual ou superior a 30 mm (R30mm) e numero maximo de dias secos consecutivos no ano (CDD). Os resultados referentes as climatologias dos indicadores mostram que os maximos de PRCPTOT se encontram a barlavento da Serra do Castelo (2097 mm) e sobre a Serra do Caparao (1890 mm). PRCPTOT e reduzida em direcao ao norte do estado, onde um minimo de 873 mm ocorre sobre o sul da mesorregiao Noroeste, uma area afastada do oceano e a sotavento da Serra do Castelo. A distribuicao espacial dos demais indices de precipitacao acompanham o padrao descrito para PRCPTOT, ou seja, maximos (minimos) de R95p, RX5day e R30mm e minimo (maximo) de CDD sobre as regioes serranas (mesorregioes Noroeste e Litoral Norte). A frequencia e intensidade dos dias chuvosos e da precipitacao diaria extrema estao aumentando no estado do Espirito Santo, principalmente na regiao sul. Alem disso, aumentos em CDD predominam no estado, indicando um prolongamento da estacao seca e, portanto, uma ma distribuicao da precipitacao ao longo do ano.

Resumo O objetivo deste estudo é avaliar o desempenho das simulações por conjunto do modelo Eta-5km do Instituto Nacional de Pesquisas Espaciais para um caso de chuva intensa ocorrido na Bacia do Rio Paraíba do Sul em janeiro de 2000, durante um evento de Zona de Convergência do Atlântico Sul. O conjunto de simulações é formado por 5 membros, denominados de acordo com suas parametrizações convectiva (Betts-Miller-Janjic - BMJ ou Kain-Fritsch - KF) e de microfísica (Ferrier ou Zhao): CNTRL (BMJ/Ferrier); KF (KF/Ferrier); KFMX (KF com fluxo de momentum/Ferrier); KFMXP (KF com fluxo de momentum e força do gradiente da perturbação da pressão/Ferrier) e ZHAO (BMJ/Zhao). As simulações são realizadas com horizontes de 24 até 120 h e condições de contorno inicial e lateral provenientes do “Climate Forecast System Reanalysis”. Os resultados indicam que todos os membros são capazes de posicionar a banda de chuva aproximadamente na mesma localização observada. O modelo, apesar de subestimar os valores das maiores pluviometrias diárias, simula uma frequência maior de eventos de chuva forte. Em geral, a média do conjunto apresenta melhor performance do que cada um dos membros isoladamente e as simulações com 48 h de antecedência são superiores às demais. Abstract The aim of this study is to evaluate the performance of simulations generated by the ensemble of the Eta-5km model from the National Institute for Space Research. The evaluation was performed over the Paraíba do Sul River Basin during an extreme rainfall event, occurred early in January 2000, in a South Atlantic Convergence Zone event. The 5-member ensemble is formed with different convective (Betts-Miller-Jancic - BMJ or Kain-Fritsch - KF) and microphysics (Ferrier or Zhao) parameterizations and are nominated respectively as: CNTRL (Betts-Miller-Janjic/Ferrier); KF (Kain-Fritsch/Ferrier); KFMX (Kain-Fritsch with inclusion of momentum flux/Ferrier); KFMXP (Kain-Fritsch with inclusion of momentum flux and force of the perturbation of pressure gradient/Ferrier) and ZHAO (Betts-Miller-Janjic/Zhao). The simulations are integrated up to 120 h and the initial and boundary conditions were taken from the Climate Forecast System Reanalysis. The results indicate that all members were able to position the rain band in about the same observed location. Although the model underestimates the highest daily precipitation amount, it simulates higher frequency of heavy rainfall events than it really occurs. In general, the ensemble mean simulation presents higher performance than each individual members and the 48-h simulations are better than the other forecast lead times.

In this work a survey of extreme rainfall events and their effects on the population of the city of Rio de Janeiro is carried out over a period of approximately 63 years, from 1881 to 1996. The objective is, to recover the main events of extreme rainfall from the 19th century by the assessment of heavy rainfall reports, and to evaluate the usefulness of meteorological information in order to alert the population against disasters caused by heavy rains. Initially, cases with daily rainfall of 100 mm or greater were pre-selected. From the total of 100 pre-selected events, 82 cases were considered extreme events due to the great damages caused to the population, including deaths, injuries, material damages, landslides, floods, among others. This means the occurrence of 1.3 extreme event per year on average (82 cases in 63 years). As expected, most cases occurred in summer and fall (40% in each season) and the remaining 20% were equally distributed during spring (10%) and winter (10%).Throughout the analyzed period it was verified that the weather forecasts in the newspapers were not sufficient to alert the population in cases of heavy rains. In addition, reasonable explanations of the meteorological causes of phenomena were only informed from the 1990s.

Seasonal rainfall forecasts generated with regional Eta model for the rainy season of the São Francisco River Basin, upstream Hydroeletric Power Plant (HPP) Três Marias in Minas Gerais are evaluated in this work. The use of such forecasts as an input in energy planning models, represent a better management in the generation, transmission and distribution of electricity. However, it is well known that most of the globe, seasonal climate predictability is much reduced, since the effects of boundary conditions to determine the evolution of the average state of the atmosphere compete with internal variability associated with the chaotic instabilities and nonlinear interactions of the atmospheric flow. The forecasts of the Eta-Seasonal-15km model are initiated on days 13 to 17 October, extending until February 28, during the years 2001-2010. The evaluation results indicate that the noise (inter members variability) is higher than the signal (interannual variability), suggesting low reliability of the forecasts for the region during the rainy season. Forecasts of precipitation are underestimated and the Root Mean Square Error of 77.03 mm / month is high, almost twice its standard deviation. Note A high spatial variability of rainfall due to very steep topography, which further reduces the performance of numerical models. A hit rating category of precipitation (IACP), based on the distribution of tertiles, was applied to account for the number of times that the forecasts point to the same category of observed rainfall: rainfall below, within or above the normal range. The IACP for the whole area and during the ten years was low (mean 29%), however in the southern Basin IACP is a bit higher, around 50% to 70% in the Southeast region. The annual review of the forecasts for the entire area indicated that the best model performance occurred in 2005, when conditions ATMS negative in Pacific, near the coast of Peru were persisted in October 2005 and in fact such anomalies occurred through the month of February 2006.

In this paper, we evaluate temperature and precipitation trends over South America (SA), simulated by the regional Eta model with 20-km horizontal resolution nested to three global models: The Canadian Earth System Model Second Generation (CanESM2-ES), The Met Office Hadley Centre Global Environmental Model - Earth System (HadGEM2-ES) and the Model for Interdisciplinary Research on Climate version 5 (MIROC5). The simulated trends are compared to observed trends (OBS) using six (four) extreme temperature (precipitation) indices recommended by the Expert Team on Climate Change Detection and Indices. In both simulations and OBS, extreme temperature trends over Amazon (AMZ) and Northeast Brazil (NEB) are higher than over South East SA (SESA) and West SA (WSA). Also, trends based on maximum temperatures are, in general, smaller than those based on minimum temperatures. The three downscaling simulations reproduce these features. The temperature simulations of the Eta-CanESM2 (Eta-MIROC5) show the largest (smallest) trends among the three simulations. The Eta-MIROC5, performs better than the other two simulations, reproducing the signals and the magnitudes of the extreme temperature trends, and some cooling trends over SESA, as shown in the observation. Precipitation trends from the three simulations do not compare well with observations, such as temperature trends. However, Eta-MIROC5 presents the best simulations, showing increase in the magnitude of the precipitation extremes over most of SA. The results from the three simulations presented here will be further used for the assessment of climate change projections in the SA region.

In this study, we document the air temperature and precipitation changes between present-day conditions and those projected for the period 2041-2070 in the state of Rio de Janeiro (Brazil) by means of Eta driven by HadCM3 climate model output, considering the variation among its four ensemble members. The main purpose is to support studies of vulnerability and adaptation policy to climate change. In relation to future projections of temperature extremes, the model indicates an increase in average minimum (maximum) temperature of between +1.1°C and +1.4°C (+1.0°C and +1.5°C) in the state by 2070, and it could reach maximum values of between +2.0°C and +3.5°C (+2.5°C and +4.5°C). The model projections also indicate that cold nights and days will be much less frequent in Rio de Janeiro by 2070, while there will be significant increases in warm nights and days. With respect to annual total rainfall, the Northern Region of Rio de Janeiro displays the greatest variation among members, indicating changes ranging from a decrease of -350 mm to an increase of +300 mm during the 21st century. The southern portion of the state has the largest increase in annual total rainfall occurring due to heavy rains, ranging from +50 to +300 mm in the period 2041-2070. Consecutive dry days will increase, which indicates poorly time distributed rainfall, with increased rainfall concentrated over shorter time periods.

A Climate Change Index (CCI) was designed to assess the degree of susceptibility to the climatic extremes projected for the future. Climate projections for the period 2041-2070 are extracted from the numerical integrations of INPE’s Eta-HadCM3 model, using the SRES A1B emissions scenario. Five indicators were chosen to represent the climatic extremes: Total annual precipitation, precipitation on the days of heavy rain, the maximum number of consecutive dry days in the year and the annual mean maximum and mean minimum temperatures. The methodology was applied to the state of Parana. The results point to a very strong warming in 99% of the municipalities, with temperature increases between 6 and 8 times greater than the variance observed in the present climate. On the other hand, projections of precipitation do not indicate major changes in relation to present behavior.

Four sets of downscaling simulations based on the Eta Regional Climate Model forced by two global climate models, the HadGEM2-ES and the MIROC5, and two RCP scenarios—8.5 and 4.5, have been carried out. The objective of this work is to assess the climate change over South America based on the Eta simulations. The future changes are shown in timeslices of 30 years: 2011-2040; 2041-2070 and 2071-2100. The climate change response of the Eta simulations nested in HadGEM2-ES is larger than the Eta nested in MIROC5. Major warming area is located in the central part of Brazil. In austral summer, the reduction of precipitation in the central part and the increase in the southeastern part of the continent are common changes in these simulations, while the EtaHadGEM2-ES intensifies the decrease of precipitation in central Brazil, the Eta-MIROC5 expands the area of increase of precipitation in southern Brazil toward the end of the century. In austral winter, precipitation decrease is found in the northern part of South America and in most of Central America, whereas the reduction in southeastern South America is limited to near coastal region. The time series of temperatures show that warming trends are larger in the Eta-HadGEM2-ES than in the Eta-MIROC5 simulations. Heavier precipitation rates are projected in the Central-South of Brazil toward the end of the century. Increase in the length of consecutive dry days (CDD) in Northeast of Brazil and the decrease of consecutive wet days (CWD) in the Amazon region are common features in these simulations.

To provide long-term simulations of climate change at higher resolution, Regional Climate Models (RCMs) are nested in global climate models (GCMs). The objective of this work is to evaluate the Eta RCM simulations driven by three global models, the HadGEM2-ES, BESM, and MIROC5, for the present period, 1961-1990. The RCM domain covers South America, Central America, and Caribbean. These simulations will be used for assessment of climate change projections in the region. Maximum temperatures are generally underestimated in the domain, in particular by MIROC5 driven simulations, in summer and winter seasons. Larger spread among the simulations was found in the minimum temperatures, which showed mixed signs of errors. The spatial correlations of temperature simulations against the CRU observations show better agreement for the MIROC5 driven simulations. The nested simulations underestimate precipitation in large areas over the continent in austral summer, whereas in winter overestimate occurs in southern Amazonia, and underestimate in southern Brazil and eastern coast of Northeast Brazil. The annual cycle of the near-surface temperature is underestimated in all model simulations, in all regions in Brazil, and in most of the year. The temperature and precipitation frequency distributions reveal that the RCM and GCM simulations contain more extreme values than the CRU observations. Evaluations of the climatic extreme indicators show that in general hot days, warm nights, and heat waves are increasing in the period, in agreement with observations. The Eta simulations driven by HadGEM2-ES show wet trends in the period, whereas the Eta driven by BESM and by MIROC5 show trends for drier conditions.

This chapter presents a description of the meteorology of the Campos Basin Region, including temperature and relative humidity 2 m from the surface, mean sea level atmospheric pressure (MSLP) and winds 10 m from the surface. The chapter starts with a general description of the climatology of the Brazilian Southeast Region and its adjoining ocean. A characterization of the Campos Basin climate ensues, followed by an underscoring of the systems which may cause strong winds in the basin. A summary of all elements covered in previous sections is presented at the end of the chapter.

A study on the detection and future projection of climate change in the city of Rio de Janeiro is here presented, based on the analysis of indices of temperature and precipitation extremes. The aim of this study is to provide information on observed and projected extremes in support of studies on impacts and vulnerability assessments required for adaptation strategies to climate change. Observational data from INMET’s weather stations and projections from INPE’s Eta- HadCM3 regional model are used. The observational analyses indicate that rainfall amount associated with heavy rain events is increasing in recent years in the forest region of Rio de Janeiro. An increase in both the frequency of occurrence and in the rainfall amount associated with heavy precipitation are projected until the end of the 21st Century, as are longer dry periods and shorter wet seasons. In regards to temperature, a warming trend is noted (both in past observations and future projections), with higher maximum air temperature and extremes. The average change in annual maximum (minimum) air temperatures may range between 2℃and 5℃(2℃and 4℃) above the current weather values in the late 21st Century. The warm (cold) days and nights are becoming more (less) frequent each year, and for the future climate (2100) it has been projected that about 40% to 70% of the days and 55% to 85% of the nights will be hot. Additionally, it can be foreseen that there will be no longer cold days and nights.

Comparações entre as previsões do modelo Eta-5km e observações nas Plataformas de Coleta de Dados meteorológicas em Cunha, Curucutu, Itanhaém, Paraibuna, Picinguaba, Santa Virgínia e São José dos Campos, localizadas na região da Serra do Mar (SP), são realizadas para o ano de 2008. A temperatura a 2 m, pressão atmosférica ao nível da estação, ventos a 10 m e precipitação são avaliados para as previsões de 24, 48 e 72 horas. Os resultados mostraram que a pressão atmosférica ao nível da estação foi subestimada (superestimada) em Paraibuna e Picinguaba (Cunha e Curucutu), devido a diferenças entre a altitude do modelo e a altitude real da estação, porém os ciclos diurnos foram bem previstos, apresentando dois máximos (0 e 12 Z) e dois mínimos (6 e 18 Z), como observados. Para a pressão atmosférica a performance do modelo é superior na previsão de 48-h. O ciclo diurno da temperatura do ar foi muito bem previsto em todas as localidades. Os valores de correlação temporal entre as previsões e observações foram bem elevados, oscilando entre 73 e 91%. Para algumas localidades verificou-se que ocorre superestimativa da temperatura do ar (cerca de 3ºC em Curucutu e Santa Virgínia e 2ºC em Itanhaém), e que tal erro é sistemático. A previsão de temperatura do ar com 24-h de antecedência foi superior às demais. De forma geral o modelo apresentou uma tendência de subestimar (superestimar) a freqüência de ocorrência de ventos calmos cuja velocidade é inferior a 1 m.s-1 (fortes – superior a 7 m.s-1). A direção dos ventos é a variável mais difícil de prever devido provavelmente às diferenças entre a topografia do modelo e a topografia real, contudo nota-se que o modelo produz o giro característico na direção ao longo do dia, provocado pelo aquecimento diurno. Os totais pluviométricos mensais são bem previstos para a maior parte das localidades, contudo em Itanhaém, Paraibuna e principalmente em Picinguaba os totais mensais foram superestimados. Da análise da precipitação diária conclui-se que em geral o modelo superestima a frequência de ocorrência de eventos de chuva (valores diários maiores ou iguais a 0,3 mm). Por outro lado, o modelo apresenta a melhor performance também para prever tais eventos, com maiores valores de ETS, BIAS e índice de acerto (cerca de 90%). As análises mostram que uma das fontes de erro do modelo está relacionada à sua topografia.

A turbulência em ar claro (Clear Air Turbulence - CAT), que ocorre freqüentemente próximo à região de corrente de jato, geralmente em altitudes entre 10.000 e 12.000 m, pode provocar sérios riscos para a aviação. Desta forma, previsões acuradas desse fenômeno contribuem na prevenção de acidentes aéreos e desconforto durante o vôo. Indicadores capazes de detectar esse fenômeno, como turbulência Brown (fim), Ellrod (ETI) e o de número de Richardson (Ri) foram calculados a partir das saídas do modelo regional ETA. As previsões de tais indicadores são avaliadas para 2 eventos de 24 de junho de 2003 e de 17 de agosto de 2006, e confrontadas com as informações contidas nas cartas de tempo significativo SIGWX. Os resultados mostram que os três indicadores de turbulência apresentaram boa correlação com as cartas SIGWX. O estudo mostrou a utilidade das previsões do modelo ETA para ajudar a entender o mecanismo da turbulência e para indicar a ocorrência do fenômeno com maior antecedência, por exemplo: 48h ou 72h comparado às 24h de antecedência das cartas SIGWX. The Clear Air Turbulence (CAT) which is frequently observed near jet stream regions, usually in the layer between 10,000 and 12,000 m, may cause serious damages to aviation, reaching airplanes without warning. Therefore, predictions of this phenomenon can help to prevent physical damages and discomfort for the crew and passengers. Numerical weather prediction models have been used as powerful tools for operational forecasts of this phenomenon, by application of some indices in the determination of the turbulence areas. In this work, the Brown, Ellrod and Richardson number indices, calculated from ETA model outputs, are used to detect turbulence. The verification was accomplished for 2 events on 24 June 2003 and 17 August 2006 and was based on SIGWX charts. The results show that the three indices correlated well with SIGWX charts. This study showed that the use of ETA model forecasts could help to understand the mechanism of turbulence and to increase the forecast lead time to about 48h or 72h, as compared to 24-h forecast SIGWX maps.

We compared forecasts of the Center for Weather Prediction and Climate Studies (Centro de Previsão de Tempo e Estudos Climáticos - CPTEC) General Circulation Model (GCM) and the mesoscale Eta Model with observations undertaken at the Rondonia Coordinated Enhanced Observing Period (CEOP) reference site, Brazil, for the dry period between 1 July and 1 September 2001. The Rondonia site is located in the Jaru Biological Reserve Area in the state of Rondonia within the Amazon region. The site is forested and is one of the Reference Sites of the Large-Scale Biosphere-Atmosphere Experiment in the Amazon Basin (LBA) Continental-Scale Experiment (CSE). Time series and mean diurnal cycles of precipitation, near-surface temperature, latent and sensible heat fluxes, surface incoming shortwave and net radiation fluxes are shown for 24-h and 48-h forecasts. In the global model, the predicted incoming shortwave radiation and net radiation are similar to observed values; however, this is accompanied by large overestimate of deep clouds and precipitation. Partition of the available energy results in an over-estimate of the sensible heat fluxes and an underestimate of the latent heat fluxes. The latent heat fluxes are large shortly after rain, but decay quickly. No clear improvement is noted in the 48-h forecasts compared with the 24-h forecasts. The Eta Model is a grid-point limited-area model. Its precipitation forecasts are similar to observations; however, the model overestimates the incoming shortwave radiation, resulting in excessive net radiation. The Eta sensible and latent heat fluxes are both overestimated, and 48-h forecasts produce small improvements over the 24-h forecasts. Near-surface temperatures are overestimated by both models. The global model requires a reduction in precipitation production, and both models require a reduction in incoming short-wave radiation at the surface. © 2007, Meteorological Society of Japan.

RESUMO Este capitulo apresenta uma descricao da meteorologia da regiao da Bacia de Campos, incluindo a temperatura e a umidade relativa do ar a 2 m da superficie, a pressao atmosferica ao nivel medio do mar (NMM) e os ventos a 10 m. Inicialmente, e feita uma descricao geral da climatologia da Regiao Sudeste do Brasil e do oceano adjacente. Em seguida e apresentada uma caracterizacao do clima da Bacia de Campos e na sequencia destacam-se os sistemas responsaveis pela ocorrencia de ventos fortes na Bacia de Campos. Finalmente, e apresentada uma sintese considerando todos os elementos abordados no texto.

The objective of this work is to assess changes in three metropolitan regions of Southeast Brazil (Rio de Janeiro, Sao Paulo, and Santos) based on the projections produced by the Eta Regional Climate Model (RCM) at very high spatial resolution, 5 km. The region, which is densely populated and extremely active economically, is frequently affected by intense rainfall events that trigger floods and landslides during the austral summer. The analyses are carried out for the period between 1961 and 2100. The 5-km simulations are results from a second downscaling nesting in the HadGEM2-ES RCP4.5 and RCP8.5 simulations. Prior to the assessment of the projections, the higher resolution simulations were evaluated for the historical period (1961–1990). The comparison between the 5-km and the coarser driver model simulations shows that the spatial patterns of precipitation and temperature of the 5-km Eta simulations are in good agreement with the observations. The simulated frequency distribution of the precipitation and temperature extremes from the 5-km Eta RCM is consistent with the observed structure and extreme values. Projections of future climate change using the 5-km Eta runs show stronger warming in the region, primarily during the summer season, while precipitation is strongly reduced. Projected temperature extremes show widespread heating with maximum temperatures increasing by approximately 9 °C in the three metropolitan regions by the end of the century in the RCP8.5 scenario. A trend of drier climate is also projected using indices based on daily precipitation, which reaches annual rainfall reductions of more than 50 % in the state of Rio de Janeiro and between 40 and 45 % in Sao Paulo and Santos. The magnitude of these changes has negative implications to the population health conditions, energy security, and economy.

The Smoke, Clouds, and Radiation-Brazil (SCAR-B) field experiment was conducted in central Brazil and southern Amazonia during the period August 15 to September 20, 1995. This paper presents an overview of atmospheric conditions during the SCAR-B period. A meteorological office was established in Brasilia to support the mission flights and field activities. All the meteorological data collected during the SCAR-B have been archived and are available to the scientific community. The meteorological conditions throughout the SCAR-B period of August and September 1995 were near climatological conditions. Few synoptic-scale waves traveling from southeastern Pacific reached Brazil, therefore the SCAR-B period was characterized by long periods of low humidity, dryness, little cloudiness, or rain, and haze events. The stable situation was interrupted due to the penetration of a frontal system on September 20, 1995, and a second and more rain-producing one on September 28, 1995. Those two frontal systems in a period of 10 days brought an end to the dry season. Air particle trajectories show that most of the smoke below 4 km from Amazonia was transported to the south and then to the east exiting the continent at 25°S–30°S. Radiative transfer calculations carried out for the clear sky gaseous and aerosol atmosphere show the decrease of the solar radiation absorption in the atmosphere-surface system due to smoke aerosol loading at the value from 5 to 50 W m−2 depending on the aerosol optical thickness, single-scattering albedo, and solar zenith angle.

In this work, the CPTEC/INPE's Eta model (8 km and 40 km) forecasts, with 72 hours in advance, are evaluate for 25 intense rainfall cases, occurred in the period 2005-2012, at São Francisco River Basin, upstream Três Marias Hydroelectric Power Plant, in Minas Gerais. The objective is to contribute to the improvement of intense rainfall forecasts in the studied area. Evaluation of rainfall forecasts is made objectively and subjectively, comparing them with observational data. Moreover, synoptic fields forecasts for several variables are compared with the same fields of ERA-Interim Reanalysis (ECMWF). The Eta model forecasts for 25 intense rainfall cases were generated initially nesting Eta-40km model to the CPTEC/INPE's Global model (T126L28). Finally, the Eta-8km model is integrated using as initial conditions the NCEP analysis and as lateral boundary conditions the Eta-40km model forecasts, updated every 6 hours. Considering the 25 intense rainfall cases, evaluating objetively the rain, Eta-8km has better (worst) performance compared to Eta-40km, to predict daily moderate to strong (weak) precipitation. Based on the subjective evaluation, it is noted that when CPTEC/INPE's Global model fails in positioning the active meteorological system, both versions of Eta model are affected. In cases where meteorological systems are more pronounced, as in the 25 case, it increases the accuracy of both Eta model versions, with Eta-8km showing better results than Eta-40km. Neste trabalho, as previsões do modelo Eta do CPTEC/INPE, em duas resoluções espaciais (8 km e 40 km), com 72 h de antecedência, são avaliadas em 25 casos de chuvas intensas ocorridos no período de 2005 a 2012 na Bacia do Rio São Francisco, à montante da Usina Hidrelétrica de Três Marias, em Minas Gerais. O objetivo do trabalho é contribuir para a melhoria das previsões de chuva na área em estudo. A avaliação das previsões de precipitação é feita objetivamente e subjetivamente, confrontando-as com dados observacionais coletados em 35 postos pluviométricos na área em estudo. Além disso, os campos sinóticos previstos para algumas variáveis são comparados com os mesmos campos da Reanálise ERA-Interim do ECMWF. As previsões do modelo Eta para os 25 casos de chuvas intensas selecionados são geradas inicialmente aninhando-se o modelo Eta-40km ao modelo Global do CPTEC/INPE (T126L28). Finalmente o modelo Eta-8km é integrado recebendo como condições iniciais as análises do NCEP e como condições de contorno lateral as previsões do modelo Eta-40km, atualizadas a cada 6 horas. Considerando-se os 25 eventos de chuvas intensas, avaliando-se a chuva objetivamente, o Eta-8km apresenta melhor performance comparado ao Eta-40km, para prever a chuva diária moderada a forte e pior performance para prever chuva fraca. Baseado na avaliação subjetiva, nota-se que quando o modelo Global do CPTEC/INPE erra o posicionamento do sistema meteorológico atuante, ambas as versões do modelo Eta são afetadas. Nos casos em que os sistemas meteorológicos são mais pronunciados, como no caso 25, aumenta o grau de acerto das versões do modelo, com o Eta-8km apresentando melhores resultados do que o Eta-40km.

In this paper it is elaborated a climatology of air temperature and precipitation and an analysis of trends in climate extremes of such variables for the State of Rio de Janeiro, using observational data between 1961 and 2012. The climatology shows average minimum temperatures ranging between 9.5 and 11ºC (15.5 to 17ºC) in winter (summer) in the mountainous region. Higher values occur mainly on the coast, where the average minimum temperature ranges between 17 and 18.5ºC (21.5 to 23ºC) in winter (summer). The lowest average maximum temperatures range between 21.5 and 23ºC (26 and 27.5ºC) in winter (summer) in the mountainous region. The highest values are in the Metropolitan Region and in the North/Northwest area, ranging between 26 and 27.5ºC (32 and 33.5ºC) in winter (summer). The annual rainfall shows maxima in higher areas (about 2500 - 2800 mm per year) and minima in the regions of marshland and coastline (between 700 and 1300 mm per year). For the observed trends in climate extremes of temperature, the Metropolitan Region and the North and Northwest Region of the State indicate statistically significant increases in mean maximum temperature (between +0.01 and +0.08ºC/year). It is also noted significant rise trends in the percentage of warm nights and days in almost the entire State (between +0.1 and +0.6 %days/year). As for rain, it is observed that there is a statistically significant upward trend in the annual rainfall totals in the Baixadas Litorâneas (between +4.0 and +32.0 mm/year). Also, it is verified a significant increase in rainfall totals of more heavy rains in the year in the Baixadas Litorâneas and in part of the Metropolitan Region, with magnitudes between +2.0 and +20 mm/year. Neste trabalho elabora-se uma climatologia da temperatura do ar e da precipitação e uma análise das tendências nos extremos climáticos de tais variáveis para o estado do Rio de Janeiro, a partir de dados observacionais entre 1961 e 2012. Os resultados da climatologia mostram temperaturas mínimas médias oscilando entre 9,5 e 11ºC (15,5 e 17ºC) no inverno (verão) na região Serrana. Valores mais elevados ocorrem principalmente no litoral, onde as médias de temperatura mínima variam entre 17 e 18,5ºC (21,5 e 23ºC) no inverno (verão). As menores temperaturas máximas médias oscilam entre 21,5 e 23ºC (26 e 27,5ºC) no inverno (verão) na região Serrana e os valores mais elevados encontram-se na região Metropolitana e no Norte/Noroeste Fluminense, oscilando entre 26 e 27,5ºC (32 e 33,5ºC) no inverno (verão). A precipitação anual apresenta máximos em áreas elevadas (cerca de 2500 a 2800 mm ao ano) e mínimos sobre as regiões de baixada e de costa (entre 700 e 1300 mm ao ano). Para as tendências observadas nos extremos climáticos de temperatura, a região Metropolitana e a região Norte e Noroeste do estado apontam para aumentos estatisticamente significativos da temperatura máxima média (entre +0,01 e +0,08ºC/ano). Notam-se também tendências estatisticamente significativas de elevação na porcentagem de noites e de dias quentes em quase todo o estado (entre +0,1 e +0,6 %dias/ano). Quanto à chuva, observa-se que há uma tendência estatisticamente significativa de aumento dos totais pluviométricos anuais nas Baixadas Litorâneas (entre +4,0 e +32,0 mm/ano). Também verifica-se uma elevação significativa dos totais pluviométricos das chuvas mais fortes do ano nas Baixadas Litorâneas e em parte da região Metropolitana, com magnitudes entre +2,0 e +20,0 mm/ano.