SummaryThe numerical regional model (Eta) coupled with the Simplified Simple Biosphere Model (SSiB) was used to investigate the impact of land cover changes on the regional climate in Amazonia. Four 13-month integrations were performed for the following scenarios: (a) no deforestation, (b) current conditions, (c) deforestation predicted for 2033, and (d) large scale deforestation. All initial and prescribed boundary conditions were kept identical for all integrations, except the land cover changes. The results show that during the dry season the post-deforestation decrease in root depth plays an important role in the energy budget, since there is less soil moisture available for evapotranspiration. In all scenarios there was a significant increase in the surface temperature, from 2.0 C in the first scenario, up to 2.8 C in the last one. In both the scenarios (b) and (c), the downward component of the surface solar radiation decreased due to an increase in the cloud cover over the deforested areas, which contributed to a further reduction of the net radiation absorbed at the surface. The cloud mechanism, where an increase in albedo is balanced by an increase in downward solar radiation, was not detected in any of these scenarios. In scenarios (a), (b) and (c), a negative feedback mechanism was observed in the hydrological cycle, with greater amounts of moisture being carried to the deforested areas. The increase in moisture convergence was greater than the reduction in evapotranspiration for both scenarios (b) and (c). This result, and the meso-scale thermodynamic processes caused an increase in precipitation. A different situation was observed in the large-scale deforestation scenario (d): a local increase of moisture convergence was observed, but not sufficiently intense to generate an increase in precipitation; the local evapotranspiration decrease was dominant in this scenario. Therefore, the partial deforestation in Amazonia can actually lead to an increase in precipitation locally. However, if the deforestation increases, this condition becomes unsustainable, leading to drier conditions and, consequently, to reduced precipitation in the region.

Este artigo traz uma perspectiva histórica da evolução do conhecimento sobre a reciclagem de precipitação e fornece uma visão crítica do estado da arte atual. São retratadas as principais fontes de umidade para a precipitação na Amazônia e o transporte de vapor d'água sobre a América do Sul. A quantificação do mecanismo de reciclagem é um indicador da importância dos processos de superfície e do clima no ciclo hidrológico, assim como da sensibilidade climática relacionada às alterações nesses processos. Os aspectos climatológicos da reciclagem na América do Sul mostram que a contribuição advectiva é mais importante para a precipitação sobre a Amazônia e o Nordeste do Brasil, ao passo que na região Centro-Sul a contribuição local tem importante papel na precipitação. Estima-se que a reciclagem de precipitação na Amazônia é da ordem de 20-35%. A advecção de umidade domina o fornecimento de vapor d'água em grande parte da região amazônica, entretanto, o papel da evapotranspiração local na reciclagem é mais importante no setor sul da bacia. Embora os estudos sobre reciclagem tenham produzido novos conhecimentos acerca da interação entre os processos de superfície e o ciclo hidrológico, os efeitos das mudanças climáticas globais nesse mecanismo ainda não estão completamente compreendidos.

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ResumoO objetivo desse trabalho é avaliar a distribuição dos componentes do balanço de água e da reciclagem de precipitação na bacia amazônica, abordando os mecanismos físicos associados ao processo de reciclagem. De forma geral, a bacia amazônica se comporta como um sumidouro de umidade da atmosfera, recebendo vapor d'água tanto do transporte de origem oceânica quanto da evaportranspiração da floresta por meio do processo de reciclagem de precipitação. Em escala regional, a Amazônia representa uma importante fonte de umidade para outras regiões da América do Sul, contribuindo para o regime da precipitação em outras áreas do continente. Na média, a reciclagem de precipitação é da ordem de 20% na bacia amazônica, com valores variando entre 15% na porção norte e 40% na porção sul. Dessa forma, do total da precipitação na bacia, aproximadamente, 20% é decorrente do processo de evapotranspiração local; indicando que, a contribuição local para a precipitação total representa um percentual significativo no balanço de água regional e desempenha um importante papel no ciclo hidrológico amazônico. Entretanto, as variabilidades e mudanças no sistema climático devido tanto às variações naturais quanto antropogênicas (aumento na emissão de gases estufa e desflorestamento) podem afetar a reciclagem e o ciclo hdrológico regional. Palavras-chave: Amazônia, reciclagem de precipitação, transporte de umidade, interação biosfera-atmosfera, reanálises Era-Interim. Precipitation Recycling in the Amazon Basin: The Role of Moisture Transport and Surface Evapotranspiration AbstractThe objective of this study is to evaluate the distribution of water budget components and precipitation recycling in the Amazon basin addressing the physical mechanisms involved in the recycling process. In general, the Amazon basin acts as a sink for atmospheric moisture, receiving water vapor transported from the ocean and from precipitation recycled from evapotranspiration by the forest. At the regional scale, the Amazon basin is an important source of water vapor, contributing to precipitation in other remote locations of South America. Here we show, on average, 20% of precipitation in the Amazon basin is recycled, varying between 15% in the northern portion and 40% in the southern portion. Thus, approximately 20% of the total rainfall in the basin is derived from local evapotranspiration processes indicating that the local contribution to the total precipitation represents a significant contribution to the regional water budget and plays an important role in the Amazon hydrological cycle. However, the variability and changes in the climate system due to both natural and anthropogenic forcings (such as the increase in the concentration of greenhouse gases in the atmosphere and changes in land use and land cover -deforestation) can affect the precipitation recycling and regional hydrologic cycle.

O objetivo deste estudo é avaliar os efeitos da mudança do clima durante o século XXI sobre a precipitação na Amazônia, utilizando o modelo regional Eta forçado com o cenário de emissões RCP 8.5 proveniente do modelo do sistema terrestre HadGEM2-ES. As mudanças projetadas para o clima futuro mostram que, os impactos nos componentes do balanço de umidade foram mais significativos durante a estação chuvosa e no setor sul da bacia, principalmente, no final do século. O mecanismo de retroalimentação positivo é configurado durante o verão e na média anual, isto é, a redução da convergência de umidade e da evapotranspiração à superfície agiram no mesmo sentido para reduzir a precipitação total; no entanto, o mecanismo de retroalimentação negativo é dominante no inverno, em que a redução da evapotranspiração é parcialmente compensada pelo aumento da convergência de umidade, porém, não o suficiente para inibir a redução da precipitação. A redução da precipitação total na Amazônia foi decorrente tanto da redução da precipitação de origem local quanto advectiva, sendo que a advectiva teve papel predominante devido às mudanças na circulação regional e no transporte de umidade para a bacia. Esses resultados mostram que, a mudança do clima pode afetar de forma significativa os componentes do balanço de água na Amazônica, implicando em graves consequências ecológicas ao bioma, tais como: afetando a dinâmica dos ecossistemas, reduzindo a capacidade da floresta em absorver carbono, favorecendo a ocorrência de eventos extremos, aumentando a temperatura à superfície e, consequentemente, a frequência e intensidade das queimadas.  Assessment of the Effects of Climate Change on Precipitation in the Amazon Basin Using the RCP 8.5 Eta-HadGEM2-ES Model A B S T R A C TThe aim of this study is to evaluate the effects of climate change on precipitation in the Amazon basin during the 21st century using the Eta Regional Climate Model forced by RCP 8.5 emissions scenario from the HadGEM2-ES earth system model. The changes projected for future climate show that the impacts on the water budget components were more significant during the rainy season and southern basin sector, especially at the end of the 21st century. The positive feedback mechanism is configured during the summer and on average annually, i.e., the reduction of moisture convergence and surface evapotranspiration acted in the same way to reduce total precipitation. The negative feedback mechanism is seen during the winter, where the reduction of evapotranspiration is partially offset by the increase in moisture convergence, however, not sufficient to offset the reduction in precipitation. The reduction in total precipitation in the Amazon was due to both the decrease of local and advective precipitation, but the advective had a major role due to changes in the regional circulation and moisture transport over the basin. These results show that climate change can significantly affect the components of the water budget in the Amazon basin, resulting in serious ecological consequences for the biome, such as affecting ecosystem dynamics, reduction in the forest's ability to absorb carbon, causing the occurrence of extreme events, increasing the surface temperature, and hence, the frequency and intensity of fires.Keywords: Amazon basin, precipitation, water budget, Eta regional model, RCP 8.5 emissions scenario

We used climate models to assess the effects of 2 distinct anthropogenic forcings on the water budget in the Amazon basin: (1) increasing global greenhouse gases under the RCP8.5 scenario, and (2) land cover change caused by deforestation. The Eta regional climate model, driven by the Brazilian Earth System Model version 2.5 (BESM 2.5), was used to simulate the climate response under the RCP8.5 scenario and due to deforestation throughout the 21st century. Changes in energy and water budgets led to an increase in temperature that reached 5°C throughout the basin. In the RCP8.5 scenario, moisture convergence, precipitation and evapotranspiration all decreased. In this scenario, the positive feedback mechanism was predominant, as the reductions in evapotranspiration and moisture convergence acted in the same direction to reduce precipitation. In the future deforestation scenarios, reductions in precipitation were even stronger. In this case, the negative feedback mechanism predominated, in which the relative reduction in evapotranspiration was greater than the reduction in precipitation, leading to an increase in moisture convergence over the region. Changes in temperature and the water cycle were intensified in the future deforestation scenarios. These results show that the 2 anthropogenic factors can change the water budget and cause an imbalance in the climate-biome system in the Amazon basin, highlighting the need for public conservation policies to halt the increase in environmental degradation in the Amazon basin and to reduce greenhouse gases emissions due the burning of fossil fuels.

Abstract.Emissions of gases and particulates in urban areas are associated with a mixture of various sources, both natural and anthropogenic. Understanding and quantifying these emissions is necessary in studies of climate change, local air pollution issues and weather modification. Studies have highlighted that the transport sector is key to closing the world's emissions gap. 15Vehicles contribute substantially with the emission of carbon dioxide (CO 2 ), carbon monoxide (CO), nitrogen oxides (NO x ), nonmethane hydrocarbon (NMHC), particulate matter (PM), methane (CH 4 ), hydrofluorocarbon (HFC) and nitrous oxide (N 2 O).Several studies show that vehicle emission inventories are an important approach to providing a baseline estimate of on-road emissions in several scales, mainly in urban areas. This approach is essential to areas with incomplete or non-existent monitoring networks as well as for air quality models. Conversely, the direct downscale of global emission inventories in chemical transport 20and air quality models may not be able to reproduce the observed evolution of atmospheric pollution processes at finer spatial scales. To address this caveat, we developed a bottom-up vehicular emission inventory along the 258 main traffic routes from Manaus, based on local vehicle fleet data and emission factors (EFs). The results show that the light vehicles are responsible for the largest fraction of the pollutants, contributing 2.6, 0.87, 0.32, 0.03, 456 and 0.8 ton/h of CO, NO x , CH 4 , PM, CO 2 and NMHC, respectively. Including the emissions of motorcycles, buses and trucks, our total estimation of the emissions is 4.1, 1.0 , 25 0.37, 0.07, 63.5 and 2.56 ton/h, respectively. We also noted that light vehicles accounted for about 62.8%, 84.7%, 87.9%, 45.1%, 71.8%, and 33.9% and motorcycles in the order of 32.3 %, 6.5 %, 12.1 %, 6.2 %, 14.8 %, 8.7 %, respectively. Nevertheless, we can highlight the bus emissions which are around 35.7% and 45.3 % for NMHC and PM. Our results indicate a better distribution over the domain reflecting the influences of standard behavior of traffic distribution per vehicle category. Finally, this inventory provides more detailed information to improving the current understanding of how vehicle emissions contribute to the ambient 30 pollutant concentrations in Manaus and their impacts on regional climate changes. This work will also contribute to improved air quality numerical simulations, provide more accurate scenarios for policymakers and regulatory agencies to develop strategies for controlling the vehicular emissions, and, consequently, mitigate associated impacts on local and regional scales of the Amazon ecosystems. 35Key words: Vehicle emission inventories, bottom-up approach, urban air pollution, Amazon forest Geosci. Model Dev. Discuss., https://doi

ResumoO cálculo de indicadores climáticos a partir de dados observados e de modelos climáticos é uma maneira eficiente de identificar possíveis variações climáticas sobre a bacia Amazônica. Embora seja frequente a avaliação de desempenho de modelos climáticos a partir de dados de precipitação e temperatura, a avaliação de suas performances utilizando-se indicadores climáticos ainda é pouco explorada, principalmente para a bacia Amazônica. Dessa forma, o presente trabalho teve como objetivo principal quantificar e avaliar a destreza dos modelos HadGEM2-ES e Eta na representação de oito indicadores climáticos. Os indicadores foram determinados a partir do total diário de precipitação proveniente do Climatate Prediction Center. Para quantificar o desempenho de ambos modelos, foram calculados o viés e o erro médio quadrático. Estes métodos foram aplicados com base na média anual dos indicadores climáticos para o período de 1981 a 1990. Os resultados mostram que o viés dos modelos HadGEM2-ES e Eta apresenta semelhança na maioria dos indicadores climáticos. Em relação ao erro médio quadrático, observou-se que nem todos os indicadores de extremos climáticos baseados em dados de precipitação são bem representados por ambos modelos, porém o Eta apresentou melhor performance em relação ao HadGEM2-ES. Palavras-chave: indicadores de extremos climáticos, bacia Amazônica, precipitação. AbstractThe calculation of climate index from observed data and climate models is an efficient way of identifying possible climatic variations on the Amazon basin. Although it is frequent to evaluate the performance of climate models from precipitation and temperature data, the evaluation of their performances using climate index is still little explored, mainly for the Amazon basin. Thus, the present work main objective was to quantify and evaluate the dexterity of the Had-GEM2-ES and Eta models in the representation of eight climate index. The climate index was determined from the daily precipitation from the Climate Prediction Center. To quantify the performance of both models, the bias and mean square error were calculated. These methods were applied on the basis of the annual average of the climate index for the period 1981 to 1990. The results show that the bias of HadGEM2-ES and Eta models is similar in the most climate index. Regarding the mean square error, it was observed that not all climatic extremes indicators based on precipitation data are well represented by both models, but Eta presented better performance in relation to HadGEM2-ES.