Publicações

This is an observational study of the large-scale moisture transport over South America, with some analyses on its relation to subtropical rainfall. The concept of aerial rivers is proposed as a framework: it is an analogy between the main pathways of moisture flow in the atmosphere and surface rivers. Opposite to surface rivers, aerial rivers gain (lose) water through evaporation (precipitation). The magnitude of the vertically integrated moisture transport is discharge, and precipitable water is like the mass of the liquid columnmultiplied by an equivalent speed it gives discharge. Trade wind flow into Amazonia, and the north/northwesterly flow to the subtropics, east of the Andes, are aerial rivers. Aerial lakes are the sections of a moisture pathway where the flow slows down and broadens, because of diffluence, and becomes deeper, with higher precipitable water. This is the case over Amazonia, downstream of the trade wind confluence. In the dry season, moisture from the aerial lake is transported northeastward, but weaker flow over southern Amazonia heads southward toward the subtropics. Southern Amazonia appears as a source of moisture to this flow. Aerial river discharge to the subtropics is comparable to that of the Amazon River. The variations of the amount of moisture coming from Amazonia have an important effect over the variability of discharge. Correlations between the flow from Amazonia and subtropical rainfall are not strong. However, some months within the set of dry seasons observed showed a strong increase (decrease) occurring together with an important increase (decrease) in subtropical rainfall.

A máxima de que um raio não cai duas vezes no mesmo lugar não vale para o Brasil. O país tem a maior incidência de raios no mundo: cerca de 50 milhões de descargas elétricas atmosféricas atingem o solo nacional por ano, causando estragos em cons­ truções, transtornos para o setor elé­ trico e mortes. Mas, felizmente, o país avança na pesquisa sobre raios e se­ diou este ano, pela primeira vez, o 14º Congresso Internacional de Eletri­ cidade Atmosférica (Icae, na sigla em inglês). No evento, que reuniu pes­ quisadores de 25 países, várias ini­ ciativas nacionais na área foram apre­ sentadas, entre elas o lançamento da Rede Brasileira de Detecção de Des­ cargas Atmosféricas (BrasilDat) e estudos sobre o monitoramento e a prevenção de raios e sua relação com a urbanização e o fenômeno do aquecimento global.

With the declining costs of flat plate and concentrating photovoltaic (PV) systems, solar PV generation in many sunny regions in Brazil will eventually become cost competitive with conventional and centralized power generation. Detailed knowledge of the local solar radiation resource becomes critical in assisting on the choice of the technology most suited for large-scale solar electricity generation. When assessing the energy generation potential of non-concentrating, fixed flat plate versus concentrating PV, sites with high levels of direct normal irradiation (DNI) can result in cost-competitive electricity generation with the use of high concentrating photovoltaic systems (HCPV). In large countries, where the transmission and distribution infrastructure costs and associated losses typical of centralized generation must be taken into account, the distributed nature of solar radiation should be perceived as a valuable asset. In this work we assess the potential of HCPV energy generation using satellite-derived DNI data for Brazil, a large and sunny country with a continental surface of 8.5 million km(2). The methodology used in the study involved the analysis of global horizontal, latitude-tilt, and direct normal solar irradiation data resulting from the Solar and Wind Energy Resource Assessment (SWERA) Project, and an estimate of the resulting electricity production potential, based on a review of HCPV generators operating at other sites. The satellite-derived solar irradiation data, with 10 km x 10 km spatial resolution, were analysed over the whole country, in order to identify the regions where HCPV might present a considerable advantage over fixed plate PV on an annual energy generation basis. Our results show that there is a considerable fraction of the national territory where the direct normal solar irradiation resource is up to 20% higher than the latitude-tilt irradiation availability. Furthermore, these sites are located in the most industrially-developed region of the country, and indicate that with the declining costs of this technology, distributed multi-megawatt HCPV can be a good choice of technology for solar energy generation at these sites in the near future.

This study aims to evaluate the performance of NDVI, EVI and LSWI in the Pantanal, considering the main types of land cover and seasonal rainfall. For this purpose, we used data from MODIS and TRMM monthly rainfall estimates. For the dry season, results varied between NDVI (0.4 and 0.8); LSWI (0.0 and 0.4); EVI (0.2 and 0.6). All indices also showed a poor correlation with rainfall, which was below 0.25. In the rainy season, NDVI presented the highest values, between 0.6 and 0.8. Only in some sections of the Evergreen Forest class, LSWI values were higher than the NDVI. The EVI showed values between 0.2 and 0.5 and the LSWI showed intermediate values between the NDVI and EVI from 0.2 to 0.7. Although alternating at times, the Savannah (Cerrado) and Deciduous Tropical Forest (Chaco) classes, LSWI and EVI were very similar. The NDVI and LSWI showed significant correlations with rainfall in all land cover classes. The LSWI showed the greatest amplitude, in all classes, and for both seasons, indicating to be most suitable for studies in the Pantanal, especially for the Savannah and Deciduous Tropical Forest classes during the rainy season, and Evergreen Forest class during the dry season.

This research aims to analyze two easterly wave disturbance events that reached the east coast of Northeast Brazil (NEB) on 15 May 2005 and 20 June 2006. The performance of the regional Eta Model was evaluated through four sets of experiments using different horizontal resolutions (10 and 40 km) and convective parameterization schemes [BettsMillerJanjic´ (BMJ) and KainFritsch (KF)]. Through analysis of 700-hPa wind fields, all experiments, with 40- and 10-km horizontal resolutions and using the BMJ and KF schemes, were shown to well represent a trough propagating westward from about 208Wto NEB, with a 5-day forecast range. When evaluating the model sensitivity to different convective parameterizations, all the experiments showed similar results and underestimated rainfall in most of the domain. The obtained results suggest the need to extend this analysis to a larger number of cases and to test other cumulus parameterizations in order to improve the rainfall forecast in eastern NEB.

Severe hydrological droughts in the Amazon have generally been associated with strong El Niño events. More than 100 years of stage record at Manaus harbour confirms that minimum water levels generally coincide with intense warming in the tropical Pacific sea waters. During 2005, however, the Amazon experienced a severe drought which was not associated with an El Niño event. Unless what usually occurs during strong El Niño events, when negative rainfall anomalies usually affect central and eastern Amazon drainage basin; rainfall deficiencies in the drought of 2005 were spatially constrained to the west and southwest of the basin. In spite of this, discharge stations at the main-stem recorded minimum water levels as low as those observed during the basin-wide 19961997 El Niño-related drought. The analysis of river discharges along the main-stem and major tributaries during the drought of 20042005 revealed that the recession on major tributaries began almost simultaneously. This was not the case in the 19961997 drought, when above-normal contribution of some tributaries for a short period during high water was crucial to partially counterbalance high discharge deficits of the other tributaries. Since time-lagged contributions of major tributaries are fundamental to damp the extremes in the main-stem, an almost coincident recession in almost all tributaries caused a rapid decrease in water discharges during the 2005 event.

In this study we developed a methodology to identify and quantify the relationships among determinants of land cover change using a regional case study in the Brazilian Amazon. The method is based on the application of fuzzy cognitive maps (FCMs), a semi-quantitative tool that provides a structured assessment of key feedbacks in sce- nario analysis. Novel to the application of FCMs is the use of spatial data-sets as the main input to build a cognitive map. Identification of interactions between land cover determinants and strengths is based on an empirical analysis of spatially explicit data and literature review. Expert knowledge is adopted to identify the strengths and weak- nesses of the method. Potential pitfalls, such as spatial autocorrelation and scale issues, identified are intrinsic to the empirical data analysis. The outputs of the resulting FCMs are compared to the outputs of spatially explicit models under similar scenarios of change. The proposed method is said to be robust and reproducible when compared with participatory approaches, and it can endorse the consistency between demand and allocation in scenario analysis to be used in spatially explicit models.

Este artigo apresenta um estudo de verificação das previsões de chuva de um sistema de previsão do tempo por ensemble regional. O conjunto é composto por seis membros, dos quais quatro utilizam o modelo RAMS 6.0 e dois usam o WRF 3.1, inicializados com dados dos modelos globais do CPTEC ou GFS e diferentes parametrizações de convecção. A verificação foca nas previsões de chuva de 24, 48 e 72 horas e nos limiares de precipitação de 1mm, 5mm e 10mm sobre o Estado do Ceará. Os membros do ensemble apresentaram resultados superiores à persistência em todo o domínio avaliado. O modelo RAMS apresenta maior índice de acerto, principalmente no litoral norte do Estado, porém um maior falso alarme em comparação com o modelo WRF. O sistema de previsão de chuva diminui sua qualidade com o aumento dos horizontes e a intensidade da chuva que se quer prever.

A study was performed to evaluate the surface soil moisture derived from Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) sensor observations over South America. Other soil moisture and rainfall datasets were also used for the analysis. The information for the soil data came from the Eta regional climate model, and for the rainfall data from the Tropical Rainfall Microwave Mission (TRMM) satellite. Statistical analysis was used to evaluate the quality of the soil moisture and rainfall products, with estimates of the correlation coefficient (R), χ2 and Cramer’s phi (φc). The results show high correlations (R > 0.8) of the AMSR-E soil moisture products with the Eta model for different regions of South America. Comparison of soil moisture products with rainfall datasets showed that the AMSR-E C-band soil moisture product was highly correlated with the TRMM satellite rainfall datasets, with the highest values of χ2 and φ. The results show that the AMSR-E C-band soil moisture products contain important information that can be used for various purposes, such as monitoring floods or droughts in arid areas or as input within the framework of an assimilation scheme of numerical weather prediction models.

O estudo trata da caracterização morfológica do aerossol Black Carbon (BC) coletado durante os meses de março a novembro de 2008 num ponto de monitoramento em São José dos Campos-SP. O aerossol BC é um particulado inerte na atmosfera, porém, devido à sua porosidade e natureza adsortiva, atua como superfície ativa de algumas reações químicas heterogêneas, podendo estar saturado com espécies tóxicas ou carcinogênicas. Assim, aerossóis de BC podem representar um perigo para a saúde pública, além de serem considerados o segundo maior contribuinte para o aquecimento global, em termos de sua forçante radiativa direta. A técnica utilizada foi a Microscopia Eletrônica de Varredura (MEV) associada à Espectroscopia de Energia Dispersiva de raios X (EDX). Essa técnica também permite a análise qualitativa da composição elementar das partículas. A partir de classificação, por semelhança morfológica, foram identificados 6 grupos distintos de partículas: um grupo de partículas produzidas por combustão de motores; outro de partículas procedentes da ressuspensão do solo; grupo de partículas da queima de biomassa; de partículas de fuligem industrial e mais dois grupos com morfologia e composição química semelhantes e específicos da região. As principais fontes identificadas foram de combustão de motores e ressuspensão do solo, porém com influências de outras fontes naturais e antrópicas.

Seahorses (Hippocampus spp.) are globally threatened by overexploitation and habitat destruction; they are also regarded as susceptible to heavy exploitation due to some of their life-history traits. From an economic perspective, they are fishes with high monetary value and marketability. Seahorses are now listed in Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora), to ensure that the international trade is not detrimental to the survival of wild populations; the effectiveness evaluation of these international controls needs comparable monitoring data, including evaluation of spatial and temporal trends. This study assesses the seahorse trade in Brazil, aiming to detect trends in catch levels, volumes and prices. Our main findings were: the dried trade was unregulated, without formal records, and primarily domestic, although records of unreported exports existed; it was primarily sustained by incidental captures in trawl nets. The live seahorse trade was mainly destined for exports, and regulated through national quotas. Between 2002 and 2009, mean prices for dried seahorses ranged from US$1.06 +/- 0.46 (level 1 traders) to US$2.78 +/- 0.68 (end-sellers) each, while mean prices for each live seahorse traded on the domestic market (1997-2009) ranged from US$1.13 +/- 0.02 (level 1 traders) to US$10.08 +/- 1.71 (retailers). Mean declared export price (2006-2008) was 15.57 +/- 10.87. Enhanced implementation of the CITES listing in Brazil will require further research, and additional measures to address both direct and indirect fishing pressure on seahorse populations.

Os raios podem interferir e até comprometer temporariamente o sucesso de qualquer programa espacial. Acidentes com raios no setor aeroespacial, atualmente, são raros, em função das precauções tomadas nos centros de lançamento.