GOAMAZONSACWAC

Observations and Modeling of the Green Ocean Amazon: Scaling Amazon Carbon Water Couplings (SACWaC)

1 May 2014 - 31 December 2015

Lead Scientist: Manvendra Dubey

Observatory: AMF , MAO

Forests soak up 25% of the carbon dioxide (CO2) emitted by anthropogenic fossil energy use (10 Gt C y-1) moderating its atmospheric accumulation. How this terrestrial CO2 uptake will evolve with climate change in the 21st century is largely unknown. Rainforests are the most active ecosystems with the Amazon basin storing 120 Gt C as biomass and exchanging 18 Gt C y-1 of CO2 via photosynthesis and respiration and fixing carbon at 2-3 kg C m-2 y-1. Furthermore, the intense hydrologic and carbon cycles are tightly coupled in the Amazon where about half of the water is recycled by evapotranspiration and the other half imported from the ocean by Northeasterly trade winds. Climate models predict a drying in the Amazon with reduced carbon uptake while observationally guided assessments indicate sustained uptake. We will resolve this huge discrepancy in the size and sign of the future Amazon carbon cycle by performing the first simultaneous regional scale high frequency measurements of atmospheric CO2, H2O, HOD, CH4, N2O and CO at Manacupuru T3 site as part of DOE's GoAmazon project. Our data will be used to inform and develop DOE's CLM on the tropical carbon-water couplings at the appropriate grid scale (10-50km). Our measurements will also validate the CO2 data from Japan's GOSAT and NASA's imminent OCO-2 satellite (launch date July 2014). Our data will be used to address the following science questions 1. How does ecosystem heterogeneity and climate variability influence the rainforest’s carbon cycle response? 2. How much (or less) does nitrogen deposition (from Manaus plume) influence the rainforest carbon cycle? 3. How well do current tropical ecosystem models (e.g., CASA, CLM, etc.) carbon cycle models do at simulating the observed regional carbon cycle and its variability? The proposal is currently supported by TES (Dan Stover PM) and integrated with GoAmazon and a detailed summary is at http://campaign.arm.gov/goamazon2014/documents/AmzonSolarFTS-Science-abstract.pdf?id=61