This work aims to establish a relationship between the photosynthetically active radiation (PAR) and the global radiation (Rg) for Santa Rita do Passa Quatro (SP), during the period from February 2005 to February 2006 and evaluate its impact on gross primary production (GPP). Data of Rg (Wm-2) and PAR (μmols s-1m-2) were obtained from the mirometeorological tower located in Gleba Cerrado Giant Foot. Data analysis allowed the establishment of a linear equation to express the relationship between PAR (MJ m-2) and Rg (MJ m-2) as: PAR = 0.3787 Rg or PAR = 1.742 Rg, for PAR (μmols s-1m-2) and Rg (MJ m-2). This relationship is indicated for the GPP determination when there is no PAR measurements.
A radiação atmosférica de ondas prolongadas tem uma importância considerável nos estudos meteorológicos, bem como no aquecimento global. Por estar ligado aos gases atmosféricos e à temperatura do ar. Este artigo tem como objetivo avaliar o desempenho de doze modelos para a estimativa da radiação de onda longa atmosférica em Brasília-DF. Os dados meteorológicos utilizados neste estudo foram adquiridos a partir da rede de dados do Sistema de Organização de Dados Ambientais - SONDA. Neste estudo, os dados da temperatura do ar, umidade relativa, radiação global e radiação atmosférica de onda longa foram utilizados para os modelos avaliados. Os cálculos foram processados com médias horárias e diárias. A avaliação dos modelos e a comparação dos resultados estimados e medidos da radiação da onda longa atmosférica foram realizadas utilizando os métodos estatísticos do erro médio quadrado (RMSE), erro absoluto médio (MAE) e erro médio médio relativo (PMRE). O coeficiente de correlação de Pearson (r) e o coeficiente de determinação (R²) também foram aplicados. Os modelos que tiveram excelentes resultados foram Brunt (1932), Prata (1996), Berdahl e Martin (1984), Idso (1982) e Berger et al. (1984), uma vez que apresentaram um bom desempenho, devido aos menores valores de RMSE , MAE e PMRE
The ESECAFLOR Project artificially induces a prolonged drought period and studies the consequences on the flows of water and carbon dioxide in an Amazon Rainforest, assessing the impacts on the ecosystem in response to this exclusion of water in the soil, a fact similar to the influence of a event of El Niño. ESECAFLOR is located in the National Forest of Caxiuanã, in the municipality of Melgaço. The objective of this work is to study soil temperature and soil moisture variability in the Brazilian Amazon. The data used refer to a period of 3 years. The results indicated greater soil moisture variability in the control plot (A), when compared to the exclusion plot (B), due to the latter having water stress. In plot B, the soil moisture remained practically constant during the studied period. In relation to the soil temperature, the variations were small in both plots, but with higher values in plot B in relation to plot A, since much of the energy that reaches the surface is used as sensible heat for its heating. With the exclusion of water in the forest soil, the life cycle may suffer irreversible changes.
The Antarctic region has experienced recent climate and environmental variations due to climate change, such as ice sheets and ice shelves loss, and changes in the production, extension, and thickness of sea-ice. These processes mainly affect the freshwater supply to the Southern Ocean and its water masses formation and export, being crucial to changes in the global climate. Here, we review the infl uence of the glacial freshwater input on the Antarctic Peninsula adjacent ocean. We highlight each climate process' relevance on freshwater contribution to the sea and present a current overview of how these processes are being addressed and studied. The increase of freshwater input into the ocean carries several implications on climate, regionally and globally. Due to glacier melting, the intrusion of colder and lighter water into the ocean increases the stratifi cation of the water column, infl uencing the sea-ice increase and reducing oceanatmosphere exchanges, affecting the global water cycle. This study shows the role of each hydrological cycle processes and their contributions to the regional oceanography and potentially to climate.
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