Publication Date:
2015-11-25
Description:
The Amazon Basin is an important region for global CH 4 emissions. It hosts the largest area of humid tropical forests, and around 20% of this area is seasonally flooded. In a warming climate it is possible that CH 4 emissions from the Amazon will increase both as a result of increased temperatures and precipitation. To examine if there are indications of first signs of such changes we present here a 13-year (2000-2013) record of regularly measured vertical CH 4 mole fraction profiles above the eastern Brazilian Amazon, sensitive to fluxes from the region upwind of Santarém (SAN), between SAN and the Atlantic coast. Using a simple mass balance approach, we find substantial CH 4 emissions with an annual average flux of 52.8±6.8 mg CH 4 m -2 day -1 over an area of approximately 1 million km 2 . Fluxes are highest in two periods of the year: in the beginning of the wet season and during the dry season. Using a CO:CH 4 emission factor estimated from the profile data, we estimated an influence of biomass burning around 15% of the total flux in dry season, indicating that biogenic emissions dominate the CH 4 flux. This 13-year record shows that CH 4 emissions upwind of SAN varied over the years, with highest emissions in 2008 (around 25% higher than in 2007), mainly during the wet season, representing 19% of the observed global increase.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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