The central focus of this study was to better understand the environmental interference caused by the “Friagem” phenomenon in a forest region in the center of the Amazon, considering the micrometeorological and atmospheric chemistry aspects. In order to do so, we used data from the Amazon Tall Tower Observatory (ATTO) research site, which is part of the Large scale Biosphere-Atmosphere program in the Amazon (LBA), data from the surface stations of the international airports of Porto Velho-RO and Manaus-AM, in addition to the reanalysis of ECMWF Era-Interim (European Center for Medium-Range Weather Forecasts) and high-resolution numerical simulations designed by JULES-CCATT-BRAMS, we investigated the impacts of the advance of the Friagem in the environment of the Amazon basin scale through the ERA-interim reanalysis, with this information a cold and dry air wave was observed penetrating the Amazon region in the South/North direction, between the days 6 and 11 July, 2014. The reanalyses of day 11 showed that the south-west flow related to the coldness converged with the easterly winds in the central region of the Amazon, and the images of the infrared channel of the satellite GOES-13 showed that the interaction between these two distinct air masses generated strong convective activity in this region, when a precipitation of 21mm was also recorded in the ATTO site. The air temperature and wind direction near the surface in Porto Velho and Manaus and above the canopy in the ATTO site were analyzed, and the arrival of the “Friagem” caused a sudden fall in temperature and a predominance of winds in the South quadrant in these regions. three localities, and these effects were seen in Porto Velho between 7 and 8 July and in Manaus and ATTO site between 9 and 11 July. From this, the analyzes were concentrated in the records of the Instant tower at the ATTO site, where it was observed that the reduction of the incident radiation due to convective activity on July 11, implied a reduction in O3 concentrations from 15:00 UTC of this day, indicating an indirect interference of the “Friagem” in the chemistry of the atmosphere. Finally, the numerical simulations revealed that the cold-related flow is shallow and restricted to vertical levels of less than 500 m, in addition, the simulations also showed that the breeze circulations of the Balbina lake possibly did not influence the atmospheric chemistry in the region of the ATTO site at the time of the cold, although the center of the lake presented higher concentrations of NO2, CO and O3 in comparison to the surface of the forest in its surroundings.
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