Artigos Científicos - FAMET/IG
URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2799
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Navegando Artigos Científicos - FAMET/IG por Afiliação "ROCHA, E. J. P. Universidade Federal do Pará"
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Item Acesso aberto (Open Access) 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 MirandaObservations 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.Item Acesso aberto (Open Access) 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, AristidesThe 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.