2011-05-102011-05-102004-12OLIVEIRA, Paulo Jorge de et al. Efeitos de um evento de friagem nas condições meteorológicas na Amazônia: um estudo de caso. Acta Amazonica, online, v. 34, n. 4, p. 613-619, dez. 2004. DOI: http://dx.doi.org/10.1590/S0044-59672004000400013. Disponível em: http://www.repositorio.ufpa.br/jspui/handle/2011/2174. Acesso em:.1809-4392http://www.repositorio.ufpa.br/jspui/handle/2011/2174Observations 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.porAcesso AbertoAmazôniaFriagemClimaFluxo de CarbonoAmazonian rain forestClimateCarbon budgetArtigo de Periódico10.1590/S0044-59672004000400013