Faculdade de Meteorologia - FAMET/IG

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2798

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Agora exibindo 1 - 7 de 7

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Efeitos de um evento de friagem nas condições meteorológicas na Amazônia: um estudo de caso
(Instituto Nacional de Pesquisas da Amazônia, 2004-12) SOUZA, Paulo Jorge de Oliveira Ponte de; ROCHA, Edson José Paulino da; FISCH, Gilberto Fernando; KRUIJT, Bart; RIBEIRO, João Batista Miranda
Observations of the influence of a Cold Spell phenomena on meteorological variables and on energy and CO2 fluxes were made in a forest site near Ji-Paraná, Rondonia, during June 2001. Friagem caused a diminution of 35% at air temperature. A reduction of 75 W.m-2 from normal days (200 W.m-2) to cold days (125 W.m-2) in the mean incoming solar radiation was also observed. During the Cold Spell days, both sensible heat (H) and latent heat fluxes (LE) showed a decrease in their mean daily value, showing a difference from normal days of 8 e 34%, respectively. The CO2 concentration remained constant, without increase during the night, due to the windy condition of cold days. During normal days the mean diurnal CO2 flux (-2,44 mmol m-2 s-1) was lesser than that one at phenomena days (-5,78 mmol m-2 s-1), while the mean nocturnal fluxes were +1,77mmol m-2 s-1 e +2,83mmol m-2 s-1 during normal and cold days, respectively.
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Impactos do avanço da soja no balanço de radiação no leste da Amazônia
(Instituto Nacional de Pesquisas da Amazônia, 2013-06) SOUZA, Paulo Jorge de Oliveira Ponte de; ROCHA, Edson José Paulino da; RIBEIRO, Aristides
The deforestation of the Amazon, especially for pasture use, has been explored by several researchers who have pointed out as a consequence, serious environmental problems. The continuous expansion of agriculture on areas of cattle ranching in the Amazon, as well as on native areas, must be seen with caution since few studies have been conducted in order to investigate which probable environmental impacts can be generated due to the presence of soybean monoculture in the region. This study evaluates the local impacts of the replacement of forest by soybean (Glycine max (L.) Merrill) on radiation balance components in an area that represents the agricultural border advancement in Amazonia. A micrometeorological experiment was installed in an area of soybean cultivation in Paragominas-PA and data from forest ecosystems were collected in Caxiuanã forests located in Melgaço-PA both during 2006 and 2007. During the soybean growing season the mean impact found in net radiation represented a reduction of 17.9% of the value commonly observed in the forest. During the off-season the impact on net radiation was 15.5%. Principal mechanisms that control these impacts were associated with the high soybean albedo and high loss of long wave radiation. Although the greatest impact occurs during the crop growing season, the time of occurrence of this negative effect is restricted to only 1/3 of the year, which leads to a higher impact of the off-season on energy balance in cumulative terms.
Acesso aberto (Open Access)
Influência de variáveis meteorológicas na produção de liteira na Estação Científica Ferreira Penna, Caxiuanã, Pará
(Instituto Nacional de Pesquisas da Amazônia, 2009-09) SILVA, Rosecélia Moreira da; COSTA, José Maria Nogueira da; RUIVO, Maria de Lourdes Pinheiro; COSTA, Antonio Carlos Lôla da; ALMEIDA, Samuel Soares
The evaluation of the influence on the exclusion of rainfall on the variation of litter production was done in Caxiuanã Forest Reserve at Ferreira Penna Scientific Station (1º 42 ' S, 51º 31 ' W) during the period from March, 2001 to February, 2003 with the objective of identifying the main meteorological variables and the main components of the monthly water balance that affected the production and decomposition of litter. This work was part of the subproject EXPERIMENT OF DROUGHT IN THE FOREST (ESECAFLOR), that aimed to study the long term impacts of drought on the water, energy and carbon dioxide fluxes in the Amazon forest. The sazonality of total litter production and its components (leaves, brushwood and reproductive parts) was well established, with the occurrence of a greater litter production during the months with lower precipitation. The monthly litter production during the experimental period ranged from 294.78 kg.ha-1 to 1758.69 kg.ha-1, with an average of 777.70 kg.ha-1. The total litter production was partitioned in leaves (61.40 %), brushwoods (18.45 %) and reproductive parts (20.14 %). The results obtained in the undisturbed plot showed a higher litter production, about 25 %, compared to the litter production in the plot under the exclusion of water. The variables more strongly correlated with litter production and its components were wind speed, global solar radiation density flux, photosynthetic active radiation density flux, soil temperature at 5 cm depth, precipitation, soil water deficit and water surplus.
Acesso aberto (Open Access)
Interações entre nuvens, chuvas e a biosfera na Amazônia
(Instituto Nacional de Pesquisas da Amazônia, 2005-06) DIAS, Maria Assunção Faus da Silva; COHEN, Júlia Clarinda Paiva; GANDU, Adilson Wagner
A review of results obtained within the Physical Climate component of LBA with respect to the interaction between the biosphere and cloud and rain formation in the Amazon Basin, in different seasons and different regions within the Basin is presented. The deforestation effect and the effect of biomass burning are discussed and the physical processes highlighted based on the data collected in several LBA intensive field campaigns. The complex interactions and the progress in the understanding their evolution based on the new datasets is presented.
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Mecanismos de controle da variação sazonal da transpiração de uma floresta tropical no Nordeste da Amazônia
(Instituto Nacional de Pesquisas da Amazônia, 2005-06) SOUZA FILHO, José Danilo da Costa; RIBEIRO, Aristides; COSTA, Marcos Heil; COHEN, Júlia Clarinda Paiva
In the present work we study the seasonal variation of the transpiration of a tropical forest, and its dependence on biotic and abiótic factors. We used data of the project CARBOPARÁ, part of The Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA), collected in the National Forest of Caxiuanã, northeastern Amazonia. The average transpiration in a 39-day period during the rainy season was 2.9 mm day-1. In a 29-day period during dry season, the average transpiration was 4.3 mm day-1. The maximum values of the surface conductivity (Cs) are 0.060 m s-1 and 0.045 m s-1 for the rainy and dry period, respectively, observed at 08:00 h local time. The aerodynamic conductance averages (Ca) 0.164 m s-1 and 0.210 m s-1, for the rainy and dry periods, respectively, while the maximum values of Ca are 0.220 and 0.375 m s-1, for the same periods, respectively. It was verified that Cs presents an inverse exponential relationship with the deficit of atmospheric water vapor, for different intervals of global solar irradiance. The hourly analysis of the decoupling factor suggests that the morning transpiration is mainly controlled by the availability of energy. During the afternoon, on the other hand, for both periods studied, the forest becomes progressively coupled to the atmosphere, denoting larger superficial control on the transpiration process.
Acesso aberto (Open Access)
Precipitação efetiva e interceptação em Caxiuanã, na Amazônia Oriental
(Instituto Nacional de Pesquisas da Amazônia, 2008-12) OLIVEIRA, Leidiane Leão de; COSTA, Rafael Ferreira da; SOUSA, Francisco de Assis Salviano de; COSTA, Antonio Carlos Lôla da; BRAGA, Alan Pantoja
The present work was carried out at the Ferreira Penna Scientific Station, in the Caxiuanã National Forest, Melgaço, Pará, Brazil (01º 42" 30"S; 51º 31" 45"W; 60 m a.s.l.). The studied region is an upland forest with closed vegetation and a mean canopy height of 35 m although some trees can be 50 m high. The species density is between 450 and 550 plants per hectare. The aim was to quantify the net precipitation, throughfall, stemflow and rain interception by vegetation, from March to December of 2004. For the throughfall measurements 25 rain gauges were randomly distributed in an one hectare area subdivided in one hundred parcels of 10 x 10 m, while the stemflow was measured on seven trees with a stem diameter at breast height representative of the area. The results showed values of net precipitation of 905.4 mm, throughfall of 885.4 mm, stemflow 20 mm and rain interception of 248 mm,corresponding respectively to 78.5%, 76.8%, 1.7% e 21.5% of the total precipitation above the canopy which was 1,153.4 mm for the study period.
Acesso aberto (Open Access)
Variação espacial e temporal da precipitação no estado do Pará
(Instituto Nacional de Pesquisas da Amazônia, 2005-06) MORAES, Bergson Cavalcanti de; COSTA, José Maria Nogueira da; COSTA, Antonio Carlos Lôla da; COSTA, Marcos Heil
Studies about the climatology of precipitation in the State of Pará are essential for the planning of agricultural activities. The variation of annual and seasonal precipitation in Pará was analysed based on a historic series of 23 years (1976 1998) of daily rainfall data. The analysis was made for 31 locations in Pará, using geographic information systems techniques, with the results presented in maps. The variability of annual and seasonal precipitation was characterized based on the coefficient of variation and the index of relative interanual variability. The variation of these coefficients for the annual precipitation in Pará was 15 to 30 %. The monthly characteristics of the wet season, in terms of beginning, end and duration, were determined using a criteria proposed by KASSAM (1979). The variation between early planting dates and late planting dates were identified by the periods of julian days of 309 319 and 353 363, respectively.

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