Airborne measurements indicate large methane emissions from the eastern Amazon basin

[1] Recent results from laboratory, field and remote sensing measurements suggest the presence of large methane emissions from the Amazon basin. Here we present regionally integrative, direct trace gas observations from two sites that confirm the presence of large fluxes of methane in eastern Amazonia. Air samples collected on aircraft near Santarem (2.9 degrees S, 55.0 degrees W) and Manaus (2.6 degrees S, 60.0 degrees W) in eastern and central Amazonia show large enhancements of CH4 that are not seen at the NOAA/ESRL background sites in the tropical Atlantic Ocean. From the surface to about four km, enhancements averaging 34 ppb and up to 200 ppb occur throughout the year and we calculate emissions averaging 27 mg CH4/m(2)/day from upwind sources.