Abstract ID: 704

Airborne measurements reveal large and seasonal CH4 fluxes for eastern and central Amazonia

Using CH4 observations made aboard aircraft above Santarem (SAN) and Manaus (MAN) between 2000 - 2008 and 2004 - 2008, respectively, we calculate surface fluxes at the regional scale for eastern and central Amazonia. Our basic method is to use a column budgeting technique with our aircraft vertical profile measurements referenced to a baseline calculated from a weighted average of NOAA/ESRL observations in the tropical Atlantic. Results from seven years of data reveal a seasonality with very high methane fluxes in the early part of the wet season (January and February) and slightly lower fluxes through the rest of the wet season. The lowest fluxes of the year appear at the beginning of the dry season (September and October). Fluxes during November and December exhibit an increase relative to the earlier part of the dry season. The atmospheric ratio of CO:CH4 reveals that dry season fluxes result from biomass burning, and that fluxes from the rest of the year have a small or negligible burning contribution. An analysis of possible emission sources suggest that wetland emissions are the dominant contribution to observed methane fluxes. However, our calculated CH4 fluxes remain significantly larger than any single source estimate or even any combination of estimates for eastern and central Amazonia.

Session:  Carbon - Scaling carbon fluxes to the region from measurements in plots, towers, and aircraft.

Presentation Type:  Poster