Airborne measurements indicate large methane emissions from the eastern Amazon basin

Abstract

[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 Amazônia. Air samples collected on aircraft near Santarém (2.9°S, 55.

Drought sensitivity of Amazonian carbon balance revealed by atmospheric measurements

“…Background CO 2 values are calculated using a linear mixing model and smoothed representations of the CO 2 (or CO) time series at RPB and ASC (Extended Data Fig. 8b) 18 as …”

“…to 4.4 km a.s.l. determined by air-mass back-trajectories calculated separately for each of (typically) 12 air samples per profile [18][19][20] in 2011. Riverine carbon outgassing 13 is included in these fluxes but contributes minimally because the riverine organic carbon loop is very nearly closed within the Amazon basin 23 , and fossil fuel emissions in the basin are negligibly small (,0.02 Pg C yr…”

“…This background represents the composition of air entering the Amazon basin from the Atlantic and is estimated as a weighted average of CO 2 at Ascension Island (ASC) and Ragged Point, Barbados (RPB) using a linear mixing model based on ASC and RPB SF 6 with weights determined from SF 6 measured at the site [18][19][20] (Methods). SF 6 is well suited for this purpose (that is, to estimate the fractional contributions of Northern and Southern Hemispheric air entering the basin) because it has a large inter-hemispheric difference (Extended Data Figure 8) and virtually no Amazonian emissions 21 .…”

Large tundra methane burst during onset of freezing

“…Northern high-latitude wetlands contribute significantly to the overall methane emissions from wetlands, but the relative source distribution between tropical and high-latitude wetlands remains uncertain 2,3 . As a result, not all the observed spatial and seasonal patterns of atmospheric methane concentrations can be satisfactorily explained, particularly for high northern latitudes.…”

Methane and carbon dioxide fluxes and their regional scalability for the European Arctic wetlands during the MAMM project in summer 2012

“…Currently, there is a lack of flux measurements at the same spatial scale as the resolution of global land surface models (typically 0.5 • ), which has been identified as a key reason why models are not able to confidently simulate the wetland CH 4 flux (Melton et al, 2013). Airborne measurements have been shown to be a powerful tool in reducing these uncertainties (Desjardins et al, 1997;Miller et al, 2007;Peischl et al, 2012), where the greater spatial coverage afforded may be an advantage over ground-based measurements under appropriate conditions, especially when testing the scalability of fluxes derived for local scales across wider areas.…”