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It is well known that most of the severe droughts in Amazonia, such as that of 1997, are El Nio-related. However, in 2005, the Amazon was affected by a severe drought that was not El Nio-related, as most of the rainfall anomalies that have happened in southwestern Amazonia are driven by sea surface temperature anomalies in the tropical North Atlantic. Earlier studies have analyzed both droughts in terms of their meteorological causes and impacts in terra firme (non-flooded) forests. This study compares the hydrological effects of both droughts on the Amazonian floodplain and discusses their potential ecological and human impacts based on an extensive literature review. The results revealed that the effects of the 2005 drought were exacerbated because rainfall was lower and evaporation rates were higher at the peak of the dry season compared to the 1997 drought. This induced a more acute depletion of water levels in floodplain lakes and was most likely associated with higher fish mortality rates. Based on the fact that the stem growth of many floodplain species is related to the length of the non-flooded period, it is hypothesized that the 1997 drought had more positive effects on floodplain forest growth than the 2005 drought. The fishing community of Silves in central Amazonia considered both droughts to have been equally severe. However, the 2005 drought was widely broadcasted by the press; therefore, the governmental mitigation efforts were more comprehensive. It is suggested that the availability of new communication technology and greater public awareness regarding environmental issues, combined with the new legal framework for assessing the severity of calamities in Brazil, are among the primary factors that explain the difference in societal response between the two droughts.

Este documento apresenta as principais contribuições do Volume 2 do Primeiro Relatório de Avaliação Nacional – RAN1, do Painel Brasileiro de Mudanças Climáticas, que foi estruturado de acordo com o escopo previamente definido pelos Coordenadores e Autores Principais dos capítulos do Grupo de Trabalho 2 (GT2). Os levantamentos aqui sintetizados resultam de uma extensa avaliação da literatura disponível no Brasil nos últimos anos, onde foram considerados os principais resultados do Grupo de Trabalho 2 do Quarto Relatório de Avaliação (AR4) do Painel Intergovernamental de Mudanças Climáticas (IPCC, em Inglês). Na elaboração do Volume 2 procurou-se: (i) identificar as vulnerabilidades do País frente ao aquecimento global; (ii) avaliar os diferentes impactos nos principais setores da economia e na sociedade de acordo com as projeções do clima até o final do século; e (iii) identificar estudos e medidas de adaptação às mudanças climáticas no Brasil até o ano de 2012.

Positive flashes correspond to approximately only 10\% of the total number of flashes produced by a thunderstorm. However, strokes with high peak currents and long continuing currents are usually present in positive flashes. Therefore, positive flashes are responsible for more intense damage than the negative ones. Positive flashes often are preceded by significant and long duration intracloud (IC) discharge activity. We observe in detail the electric field variations produced by 80 cloud-to-ground lightning flashes in 9 different storms in S. Paulo, Brazil during the summers of 2009-2011. Intracloud discharges preceding the positive cloud-to-ground flashes and some characteristics of the electric field changes produced by the return stroke that occurred at ranges of 3-80 km from the site of the electric field measurements were analyzed. All flashes presented breakdown pulses prior to the return stroke. The mean time interval between the preliminary breakdown pulse (PBP) and return stroke was 157 ms. The pulse train duration have a mean value of 3.1 ms. Only 6 out of 80 cases analyzed did not present pulse trains but only one single bipolar breakdown pulse before the return stroke. In 95\% of cases the initial breakdown pulse presented the same initial polarity of the succeeding return stroke. Time interval between pulses in a pulse train had a mean value of 280 mu s. The mean values of pulse width is 25.2 mu s. The mean values of zero-to-peak risetimes and of the 10-90\% risetimes for 72 return strokes electric field waveforms are 9.5 and 5.7 mu s respectively. The AM value of peak amplitudes of the positive return strokes fields normalized to 100 km is 17.0 V/m.

Brazils wind energy production has escalated up recently. However, the long-term wind projects do not include the yet unknown impacts of climate changes on wind power. This work is an assessment of these impacts by applying forecasts of a climate model and trend analysis over climatological time series from selected ground sites. Findings indicate a favourable scenario for wind power exploitation in Brazil on the long run.

Temos o prazer de apresentar o 3º Relatório de Atividades do Instituto Nacional de Ciência e Tecnologia para Mudanças Climáticas (INCT para MC), que resume os destaques científicos de seus 26 sub-projetos de pesquisa, no período de setembro de 2011 a março de 2013. O documento traz ainda uma descrição resumida dos objetivos, da organização, da infraestrutura e do processo de formação de recursos humanos desta que constitui a maior e mais abrangente rede interdisciplinar de instituições de pesquisa em meio ambiente no Brasil.

Quando visitou o Reino Unido em março de 2006, o presidente Lula firmou um acordo de trabalho conjunto entre Reino Unido e Brasil sobre questões relativas às mudanças climáticas. Atualmente os dois países ainda continuam trabalhando juntos, com o mesmo senso de urgência que a visita do presidente inspirou, para avaliar os impactos das mudanças climáticas e os efeitos do desmatamento sobre o clima do Brasil. Este relatório destaca o que se conseguiu até agora por meio da cooperação e da engenhosidade do INPE e o Met Office Hadley Centre (MOHC).

Agreement for the UK and Brazil to work together on climate-change issues was reached when President Lula visited the UK in March 2006. Today, our two countries still work together, with the same sense of urgency his visit inspired, to assess the impacts of climate change on Brazil and the effects of deforestation on the Brazilian climate. This report highlights what has been achieved so far through the cooperation and expertise of INPE and the Met Office.

The fast increase in importance of the solar energy resource as viable and promising source of renewable energy has boosted research in methods to evaluate the short-term forecasts of the solar energy resource. There is an increase on demand from the energy sector for accurate short-term forecasts of solar energy resources in order to support the planning and management of the electricity generation and distribution systems. The Eta model is the mesoscale model running at CPTEC/INPE for weather forecasts and climate studies. It provides outputs for solar radiation flux at the surface, but these solar radiation forecasts are greatly overestimated. In order to achieve more reliable information, Artificial Neural Networks (ANN) were used to refine short-term forecast for the downward solar radiation flux at the surfaceprovided by Eta/CPTEC model. Ground measurements of downward solar radiation flux acquired in two SONDA sites located in Southern region of Brazil (Florianópolis and São Martinho da Serra) were used for ANN training and validation. The short-term forecasts produced by ANN have presented higher correlation coefficients and lower deviations. The ANN removed the bias observed in solar radiation forecasts provided by Eta/CPTEC model. The skill improvement in RMSE was higher than 30%when ANN was used to provide short-term forecasts of solar radiation at the surface in both measurement sites.

Brazil suffers yearly from extreme weather and climate events, which can be exacerbated in a warmer climate. Although several studies have analyzed the projections of climate change in Brazil, little attention has been paid to defining the locations that can be most affected, and consequently have a more vulnerable population, in a spatially-explicit form. This study presents a spatial analysis of summarized climate change data and a joint investigation combining these possible climate changes and social vulnerability indicators in Brazil. The Regional Climate Change Index (RCCI), which can synthesize a large number of climate model projections, is used for the climate analysis, and the Socio-Climatic Vulnerability Index (SCVI) is proposed to aggregate local population vulnerabilities to the climate change information. The RCCI results show climatic hotspots emerging in Brazil, covering the western portion of the Northeast (NE), northwestern Minas Gerais state and centerwestern (CW) and northern regions (N), except northeast Pará and Amapá states. The SCVI analysis reveals major socio-climatic hotspots in the NE and several localized hotspots in some of the major Brazilian metropolitan regions, namely Manaus, Belo Horizonte, Brasília, Salvador, Rio de Janeiro and São Paulo. The two novelties of this study are a spatially detailed analysis of the RCCI in Brazil and the development of an index that can summarize the large amount of climate model information available today with social vulnerability indicators. Both indices may be important tools for improving the dialogue between climate and social scientists and for communicating climate change to policymakers in a more synthetic and socially relevant form.

The study estimated, for the first time, the greenhouse gas emissions associated with cattle raising in Brazil, focusing on the period from 2003 to 2008 and the three principal sources: 1) portion of deforestation resulting in pasture establishment and subsequent burning of felled vegetation; 2) pasture burning; and 3) bovine enteric fermentation. Deforestation for pasture establishment was only considered for the Amazon and Cerrado. Emissions from pasture burning and enteric fermentation were accounted for the entire country. The consolidated emissions estimate lies between approximately 813 Mt CO2eq in 2008 (smallest value) and approximately 1,090 Mt CO2eq in 2003 (greatest value). The total emissions associated with Amazon cattle ranching ranged from 499 to 775 Mt CO2eq, that of the Cerrado from 229 to 231 Mt CO2eq, and that of the rest of the country between 84 and 87 Mt CO2eq. The full set of emissions originating from cattle raising is responsible for approximately half of all Brazilian emissions (estimated to be approximately 1,055 Mt CO2eq in 2005), even without considering cattle related sources not explicitly estimated in this study, such as energy use for transport and refrigeration along the beef and derivatives supply chain. The potential for reduction of greenhouse gas emissions offered by the Brazilian cattle industry is very high and might constitute Brazils most important opportunity for emissions mitigation. The study offers a series of policy recommendations for mitigation that can be implemented by public and private administrators at a low cost relative to other greenhouse gas reduction options.

On average, negative cloud-to-ground (CG) lightning flashes produce 3 to 5 return strokes, and a new ground termination is produced when any stroke after the first strikes the ground in a different place. In order to understand better the physical factors that affect the formation of new ground terminations, high-speed digital video cameras with time-resolutions and exposure times ranging from 125 μs (8000 frames per second) to 2 ms (500 frames per second) were used to record images of cloud-to-ground lightning in southern and southeastern Brazil and southern Arizona (USA), between February 2003 and September 2007. Some relevant information regarding the formation of new channels was obtained from the analysis of the previous interstroke time intervals and the number of previous strokes following the same path to ground. Although most of the subsequent strokes tend to follow the previously formed channel, this tendency is not observed in the second stroke (that is, the first subsequent stroke). 52% of the new channels occur in the second stroke. Contrary to what it was generally assumed in some past studies (Kitagawa et al., 1962; Malan, 1956; Rakov and Uman, 1990; Rakov et al., 1994; Winn et al., 1973), the formation of a new channel stroke is not clearly dependent on the interstroke interval that precedes it. In general, most of the new channels occur after a single usage of the channel and in these cases the previous interstroke time interval is not an important parameter. However, when the channel is used more than once, a new channel occurs mostly after a long interstroke interval.