Close Window

CD-14 Abstract

CO2 Budget Regional Airborne Study (COBRA)-Brazil

Maria Assunção Faus da Silva Dias — IAG/USP (SA-PI)
Steven Charles Wofsy — Harvard University (US-PI)

Motivation. The Amazon Basin is a key component of the

global carbon


cycle, containing one-half of the world's undisturbed tropical forest


and accounting for ~10% of global terrestrial net primary


productivity.  Current estimates of carbon fluxes in Amazonia at the


regional and Basin scales are subject to large uncertainties that


propagate into the global carbon budget.  Regional and Basin scale


carbon exchanges fall into the "missing scale" in carbon cycle

science


due to a) dearth of CO2 observations over the continent to constrain


inverse models and b) lack of independently validated methodologies to


scale up local measurements. 



The proposed study will conduct in-situ airborne

measurements


of CO2 and CO in the lower- and mid-troposphere over the Amazon Basin.


The proposed strategy for observations and analysis will provide


direct estimates of carbon fluxes at the missing regional and Basin


scales.  We plan to conduct this study during both wet and dry seasons


to capture the seasonal variability and to complement LBA airborne


remote-sensing missions. 




Objectives



directly quantify regional and Basin-scale fluxes in

Amaztnia using


airborne measurements of CO2 and other tracers in and above the


planetary boundary layer (PBL);







  • establish the relationships

    between vertical concentration


    gradients and exchange fluxes observed at the eddy flux towers in LBA


    and over adjacent regions;





  • test hypotheses

    central to LBA that Amazonia is a major net


    source or sink for CO2;





  • characterize

    horizontal and vertical distributions of


    atmospheric CO2 over Amazonia for the purposes of planning remote


    sensing instrumentation






Approach



The proposed strategy has been successfully implemented

in a


pilot study (COBRA 2000) conducted over North America and consists of


the following complementary approaches:







  • Lagrangian regional experiments: diurnal airborne

    measurements of


    CO2, CO, and H2O within and above the PBL in an airmass-following


    framework which yields regional fluxes and their variations across


    different disturbance regimes. 





  • Eulerian experiments: vertical profiles at different

    times of the day


    over selected locations yield first-order estimates of carbon fluxes


    and define the diurnal variations for each region  





  • Large-scale surveys: sampling of large-scale CO2

    distribution along


    the synoptic flow pattern, combined with knowledge of diurnal


    variations from the Eulerian experiments, gives Basin-scale fluxes





  • Hemispheric-scale cross-sections: observations during

    transit flights


    between North Dakota and Brazil will enable construction of CO2


    cross-sections that span from the mid- to tropical latitudes








Deliverables



Direct estimates of CO2 fluxes at regional and Basin

scales to test


ideas about net sources or sinks of CO2 in Amazonia, and against which


methods for scaling up local measurements can be evaluated, including:







  • Regional scale (~200-300km) CO2 fluxes in disturbed and

    undisturbed


    regions of Amazonia





  • Basin scale flux estimates derived from large-scale

    horizontal and


    vertical gradients





Vertical and horizontal distributions of CO2 in the

troposphere over


Amazonia and between the American Midwest and Brazil that:







  • improve estimates from inverse studies by filling an

    observational


    gap





  • constrain CO2 fields generated by coupled

    atmosphere-biosphere models





  • assist in the development of space-borne sensors for

    measuring


    atmospheric CO2





  • evaluation of a simpler method to quantify carbon

    fluxes, using


    routine atmospheric profiling over the same location, which can be


    more widely adopted.



Close Window