A micrometeorological study was carried out during the COBRA-PARÁ experiment from October 30 to November 15, 2006. The aim was to determine the radiation use efficiency (EUR) indices in the forest ecosystem and to examine the influence of variables meteorological conditions in the oscillation of the magnitudes of these indices, besides establishing linear relations between the radiative parameters and the CO2 flows. An automatic weather station was installed at a height of 52 m to continuously record meteorological parameters, such as Tar and Tsolo, UR, direction and wind speed, PRP and RSG ePARin. Eddy Correlation was used to measure CO2 flows, water vapor and sensible heat using the LI-7500 open path system. AEUR was calculated by the ratio between the CO2 flows and the radiative indexes (PARin and RNet).
