Abstract
Two major droughts in the past decade had large impacts on carbon exchange in the Amazon. Recent analysis of vertical profile measurements of atmospheric CO2 and CO by Gatti et al. (2014) suggests that the 2010 drought turned the normally close-to-neutral annual Amazon carbon balance into a substantial source of nearly 0.5 PgC/yr, revealing a strong drought response. In this study, we revisit this hypothesis and interpret not only the same CO2/CO vertical profile measurements but also additional constraints on carbon exchange such as satellite observations of CO, burned area, and fire hot spots. The results from our CarbonTracker South America data assimilation system suggest that carbon uptake by vegetation was indeed reduced in 2010 but that the magnitude of the decrease strongly depends on the estimated 2010 and 2011 biomass burning emissions. We have used fire products based on burned area (Global Fire Emissions Database version 4), satellite-observed CO columns (Infrared Atmospheric Sounding Interferometer), fire radiative power (Global Fire Assimilation System version 1), and fire hot spots (Fire Inventory from NCAR version 1), and found an increase in biomass burning emissions in 2010 compared to 2011 of 0.16 to 0.24 PgC/yr. We derived a decrease of biospheric uptake ranging from 0.08 to 0.26 PgC/yr, with the range determined from a set of alternative inversions using different biomass burning estimates. Our numerical analysis of the 2010 Amazon drought results in a total reduction of carbon uptake of 0.24 to 0.50 PgC/yr and turns the balance from carbon sink to source. Our findings support the suggestion that the hydrological cycle will be an important driver of future changes in Amazonian carbon exchange.
Original language | English |
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Pages (from-to) | 1092-1108 |
Number of pages | 17 |
Journal | Global Biogeochemical Cycles |
Volume | 29 |
Issue number | 7 |
DOIs | |
Publication status | Published - Jul 2015 |
Funding
The authors would like to thank the contributing laboratories to the ObsPack data product prototype version 1.0.4 for their efforts in performing the high precision atmospheric CO<INF>2</INF> measurements at the various locations worldwide. We would specifically like to thank the contributing persons from the following laboratories of which we have assimilated the CO<INF>2</INF> observations in CT-SAM: Insituto de Pesquisas Energeticas e Nucleares (IPEN, Brazil), NOAA Earth System Research Laboratory (U.S.A.), Environment Canada (Canada), Commonwealth Scientific and Industrial Research Organization (Australia), Laboratoire des Sciences du Climat et de l'Environnement (LSCE, France) and the RAMCES team (Reseau Atmospherique de Mesure des Composes a Effet de Serre, France), National Center For Atmospheric Research (U.S.A.), University of Bern (Switzerland), Lawrence Berkeley National Laboratory (U.S.A.), Scripps Institution of Oceanography (U.S.A.), University of Groningen (the Netherlands), Finnish Meteorological Institute (Finland), Meteorological State Agency of Spain (Spain), and the Hungarian Meteorological Service (Hungary). Observations collected in the U.S. Southern Great Plains (SGP) were supported by the Office of Biological and Environmental Research of the US Department of Energy under contract DE-AC02-05CH11231 as part of the Atmospheric Radiation Measurement Program (ARM). The biomass burning data used for this study are available from the GFED4 (http://www.globalfiredata.org), GFASv1 (https://www.gmesatmosphere.eu/fire/), and FINNv1 (http://bai.acd.ucar.edu/Data/fire/) databases. IASI was developed and built under the responsibility of Centre National d'Etudes Spatiales (CNES) and flies onboard the MetOp satellite as part of the Eumetsat Polar system. The authors acknowledge the Ether French atmospheric database (http://ether.ipsl.jussieu.fr) for distributing the IASI L1C and L2-CO data. SiBCASA and CarbonTracker model results as presented in this paper are available upon request ([email protected]). This research has been financially supported by the GEOCARBON project (EU FP7 grant agreement: 283080) and a grant for computing time (SH-060-13) from the Netherlands Organization for Scientific Research (NWO). J. W. Kaiser is funded by the MACC-III project (EU H2020 grant agreement 633080). We furthermore acknowledge the AMAZONICA NERC grant NE/F005806/1 which funded a substantial part of the greenhouse gas measurements over the Amazon used in this paper. The authors would like to thank two anonymous reviewers for their comments.
Keywords
- carbon balance
- Amazon
- drought
- biomass burning
- net biome exchange
- CO2
- ENSEMBLE DATA ASSIMILATION
- GLOBAL FIRE EMISSIONS
- ATMOSPHERIC CO2
- RAIN-FOREST
- VERTICAL PROFILES
- MODEL TM5
- BIOMASS
- FLUXES
- VARIABILITY
- SENSITIVITY