Determination of Methane Emissions in the Amazon Basin

Abstract

This project aims to determine the Methane (CH4) flux in Amazon Basin, using aircraft vertical profiles with small aircrafts, through the Column Integration Technique, and is inserted in other three projects: a Thematic Project, Carbon Tracker, financed by FAPESP (08/58120-3); the AMAZONICA project, financed by NERC; and the GEOCARBON project scheduled to start in September 2011, with european financing of the FP7 program of European Community. These projects finance vertical profiles studies in four sites distributed in Brazilian Amazon Basin, forming a large rectangle, to represent entire basin. The concentrations found in the vertical profiles reflect the resultant of all process that occurs between the Brazilian coast and the sampling site. The four sites where the vertical profiles are made in the Amazon Basin are: Santarém (SAN - 2,86ºS; 54,95ºW), in Pará State, over the Floresta Nacional do Tapajós; Tabatinga (TAB - 5,96ºS, 70,06ºW), in the Amazonas State; Rio Branco (RBA - 9,38ºS, 67,62ºW), in the Acre State; and in the Alta Floresta (ALF - 8,80ºS, 56,75ºW), in Mato Grosso State, with CH4 measurements having a range of altitudes being 300m minimum and 4420m maximum, between the years 2010 until 2013. The samples are made fortnightly and analyzed in Atmospheric Chemistry Laboratory of IPEN. To determine the CH4 flux, will be used the Column Integration Technique, where the background concentrations are subtracted from the CH4 concentrations obtained in each sampling site, to determine the real contribution of the Amazon Basin on the CH4 flux. To estimate these background concentrations, air fractions will be calculated in air masses which arrive in the study sites, using the SF6 gas concentrations as a tracer of these masses. These concentrations will be related with the concentrations of two NOAA Global Monitoring Stations, the Ascension Island and Barbados. Back trajectories will be simulated through HYSPLIT model for each profile, each 500m of altitude to determine the time that these air masses which arrive in each study site take to travel between the Brazilian coast until each site where are made the aircraft vertical profiles. Through these back trajectories will be defined the representative areas of each study site. Will be calculate too, the CH4 emission from biomass burning using Carbon Monoxide (CO) as a forest fire tracer, from CO/CH4 ratio to the Amazon Forest, and will be also possible determine the biogenic CH4 emission. From the analyses of the results obtained in each of the four study sites will be determined the CH4 emission of the Brazilian Amazon Basin, observing the flux variations obtained for each region of the Basin, corresponding the representative area to each study site, as well as the flux seasonality during all the years and during each year. Considering the air masses back trajectories, will be possible indicate the CH4 sources present in these regions for interpretation of the observed flux in the study sites.