Publicações

Satellite tracked drifters were deployed in order to study the horizontal transport and dispersion in the epilimnion of a large hydroelectric reservoir. Our study was motivated by the dispersion implications on the reservoir surface process, such as larval dispersion, turbulent mixing, point-source fertilizer, dispersion of pollutants, and many others. Our results have demonstrated the effectiveness of the drifter in estimating differential kinematic properties and horizontal dispersion. A discussion of how these parameters can be useful for the safe and efficient management of the waterway is carried out. The diffusivity observed in this study was comparable with those observed in others lakes. The average value of diffusivity coefficient (K = 2 m2s-1) was very close to the mean value observed by Stocker and Imberger (2003) (K = 2.5 m2s-1) in the Lake Kinneret. Comparing the diffusivity coefficient for the identical releases of drifters at the same time but from two slightly different locations a pronounced difference is observed. This indicates that the dispersion is sensitive to the location of the release.

Para depreender os processos de emissão, transformação e contaminação da atmosfera urbana por poluentes é de suma relevância observar diferentes parâmetros de qualidade para identificar e quantificar espécies químicas, principalmente em áreas com forte influência antropogênicas, pois a atividade industrial e a frota de veículos automotores são os principais responsáveis pela emissão de gases e particulados na atmosfera. Em meio a outros poluentes atmosféricos, o material particulado inalável em suspensão (com diâmetro aerodinâmico menor que 10 μm) tem grande importância devido à sua composição química complexa, suas propriedades físicas e os impactos nocivos na saúde humana. Neste estudo de caso, a composição química do material particulado inalável (MP10) foi determinada dosando-se os ânions (cloreto, nitrato e sulfato) e os cátions (sódio, amônio, potássio, cálcio e magnésio) maiores no extrato aquoso. O MP10 foi obtido em períodos de 24 horas no Instituto Nacional de Pesquisas Espaciais (INPE) de São José dos Campos-SP entre Março de 2010 a Fevereiro de 2011 abrangendo os períodos seco e chuvoso. As coletas foram realizadas com o auxílio de um amostrador dicotômico instalado a cerca de 20 m acima do solo no edifício CEA, tendo como substrato de coleta filtros de policarbonato. Através de análise gravimétrica estabeleceu-se a massa das frações do MP10 e para a análise dos íons no extrato aquoso utilizou-se da técnica de cromatografia a líquido de íons . A comparação entre o período chuvoso e seco para a fração grossa (MP2,5-10) aponta uma relação inversa entre a precipitação anual (P) e a concentração média anual de MP2,5-10, pois para o período seco temos: P= 114,2 mm ; MP2,5-10= 8,42 μg.m-3 e para o período chuvoso P=1104,6 mm; MP2,5-10=5,44 μg.m-3, já para a fração fina (MP2,5) a concentração média anual não apresentou alterações significativas entre o período seco: P=114,2 mm; MP2,5= 3,95 μg.m-3 e chuvoso: P= 1104,6 mm; MP2,5= 3,63μg.m-3. Quanto à concentração média dos íons maiores verificou-se que para o MP2, 5-10 a ordem decrescente dos íons é: nitrato, cálcio, sulfato, sódio, cloreto, potássio, amônio e magnésio e para o MP2,5 a ordem de predominância é: sulfato, sódio, nitrato, cálcio, potássio, cloreto, magnésio e amônio.

Extreme weather continues to preoccupy society as a formidable public safety concern bearing huge economic costs. While attention has focused on global climate change and how it could intensify key elements of the water cycle such as precipitation and river discharge, it is the conjunction of geophysical and socioeconomic forces that shapes human sensitivity and risks to weather extremes. We demonstrate here the use of high-resolution geophysical and population datasets together with documentary reports of rainfall-induced damage across South America over a multi-decadal, retrospective time domain (1960-2000). We define and map extreme precipitation hazard, exposure, affected populations, vulnerability and risk, and use these variables to analyse the impact of floods as a water security issue. Geospatial experiments uncover major sources of risk from natural climate variability and population growth, with change in climate extremes bearing a minor role. While rural populations display greatest relative sensitivity to extreme rainfall, urban settings show the highest rates of increasing risk. In the coming decades, rapid urbanization will make South American cities the focal point of future climate threats but also an opportunity for reducing vulnerability, protecting lives and sustaining economic development through both traditional and ecosystem-based disaster risk management systems.

This study analyzes the inter-annual variability (IAV) of simulations of 21 different land surface model formulations, driven by meteorological conditions measured at 8 flux towers, located in rain forest, forest-savanna ecotone and pasture sites in Amazonia, and one in savanna site in Southeastern Brazil. Annual totals of net ecosystem exchange (NEE) of carbon and evapotranspiration (ET), measured and simulated by each model for each site-year, were compared in terms of year-to-year variability and possible relation to climate drivers. Results have shown that most of models simulations for annual totals of NEE and ET, and IAV of these fluxes, are frequently different from measurements. The average of the model simulations of annual fluxes tend to respond to climatic drivers similarly to the observations, but with noticeable discrepancies. Annual measurements of NEE are negatively correlated to annual rainfall in the forest sites group. Although the ensemble of all models yields a similar result, only three model formulations reproduce a significant negative correlation of simulated NEE with rainfall. For the IAV of ET, tower measurements are controlled by annual variations of radiation and this feature is captured by the ensemble of the models, both at individual sites and when all forest sites are grouped. However, simulated ET values are also significantly correlated to the amount of precipitation in many models and in the model ensemble, while there is no significant correlation in the observations. In general, the surface models are able to reproduce the responses of fluxes to climatic drivers, but improvements are still needed to better capture their inter-annual variability.

Wild-fires release huge amounts of aerosol and hazardous trace gases in the atmosphere. The residence time and the dispersion of fire pollutants in the atmosphere can range from hours to days and from local to continental scales. These various scenario shighly depend on the injection height of smoke plumes. The altitude at which fire products are injected in the atmosphere is controlled by fire characteristics and meteorological conditions. Injection height however is still poorly accounted in chemistry transport models for which fires are sub-grid scale processes which need to be parametrised. Only recently, physically-based approaches for estimating the fire injection heights have been developed which consider both the convective updrafts induced by the release of fire sensible heat and the impact of background meteorological environment on the fire convection dynamics. In this work, two different models are used to simulate fire injection heights in contrasted meteorological scenarios: a Mediterranean arson fire and two Amazonian deforestation fires. A Eddy-Diffusivity/Mass-Flux approach, for merly developed to reproduce convective boundary layer in the non-hydrostatic meteorological model Meso-NH, is compared to the 1-D Plume Rise Model. For both models, radiosonde data and re-analyses from the European Center for Medium-Range Weather Forecasts (ECMWF) have been used as initial conditions to explore the sensitivity of the models responses to different meteorological forcings. The two models predict injection heights for the Mediterranean fire between 1.7 and 3.3 km with the Meso-NH/EDMF model systematically higher than the 1-D PRM model. Both models show a limited sensitivity to the meteorological forcings with a 2030 % difference in the injection height between radiosondes and ECMWF data for this case. Injection heights calculated for the two Amazonian fires ranges from 5 to 6.5 km for the 1-D PRM model and from 2 to 4 km for the Meso-NH/EDMF model. The difference of smoke plume heights between the two models can reach 34 km. A large difference is obtained for the windy-wet Amazonian fire by the 1-D PRM model with a injection height 1.5 km higher when ECMWF re-analyses are used compared to the run with the radiosonde forcing. For the Mediterranean case, both models forecast a plume injection height above the boundary layer, although there are evidences that this particular fire propagated near the surface, highlighting the current limitations of the two approaches.

Cloud cover is a key feature in Earth images acquired from space. Cloud cover data play a significant role in the weather forecast and climate knowledge, as well as in several human activities. Several studies have been conducted to establish a methodology and experimental setup in order to acquire reliable cloud cover data from remote sense observations performed on the surface. This research aimed at comparing ground data acquired by different systems for the same atmospheric scenario regarding cloud cover. Solar radiation data and sky images acquired at SONDA station located in Florianópolis, in 2002, were used to evaluate cloud cover. Also, cloud cover data collected at the international airport meteorological station distant 7,700 m from the SONDA station were used. This work compares these two sets of data acquired for sky scenarios with only one type of cloud. The results show good agreement in clear and completely overcast sky conditions. Future studies using longer time series will be developed in order to evaluate the influence of seasonal variability and atmospheric scenarios with several cloud types (low, medium and high clouds).

O primeiro passo para o gerenciamento participativo das Bacias hidrográficas é identificar os diferentesprotagonistas sociais que atuam na gestão dos recursos hídricos. Para que em seguida, os atores sociais, atravésdo processo de educação ambiental, na capacitação de gestores públicos, técnicos, agentes de desenvolvimentolocal, educadores, professores e lideranças em geral, saibam avaliar as demandas dos demais usuários e tomemdecisões conscientes no âmbito do Comitê de Bacia hidrográfica. A escolha da Bacia hidrográfica do Rio Munin,foi devido aos problemas ambientais e o baixo grau de instrução sobre educação ambiental na região. Assim essetrabalho teve como objetivo sistematizar os dados secundários sobre os aspectos políticos, ambientais e sociaisem toda área de abrangência da Bacia, demonstrando os passos para iniciar o processo de capilaridade efortalecimento da educação ambiental, voltados para a instrumentalização e fortalecimento do Comitê dessaBacia hidrográfica. Este trabalho baseou-se no Projeto União Pró-Águas do Alto e Médio Munin, seguindo asinformações obtidas da Rede de Monitoramento da Qualidade e Quantidade da Água, implantada peloPNMAII/MMA. Foram identificadas na Bacia do Munin 114 organizações da sociedade civil, 101 usuários, 28instituições ligadas ao governo municipal, 21 ao estadual e 2 federais que participam da implantação desseComitê. De acordo com a percepção dos moradores, uma das ações mais perturbadoras detectadas na Bacia é adevastação da mata ciliar por desmatamentos e queimadas, que causa o assoreamento do rio. O que se pôdeconstatar é que o grau de desinformação sobre a gestão das águas nos da a certeza que a implantação de umarede de educação ambiental contribuirá de forma eficaz não só na implantação do Comitê da Bacia, como paraimplantação de políticas públicas no desenvolvimento regional.