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CD-01 Abstract

Spatial Integration of Regional Carbon Balance in Amazonia

Allan Scott Denning — Colorado State University (US-PI)
Pedro Leite Silva Dias — USP - Universidade de Sao Paulo (SA-PI)

Under the new Cooperative Agreement, we will perform the

following specific tasks in very active collaboration with our colleagues at USP.









  1. Evaluate

    the new SiB3 model for a series of Amazon flux sites. This will entail

    producing or obtaining from collaborators filled micrometeorological

    timeseries data (no missing values in any “driver” variable) from the

    three Tapajos sites, and from as many other sites as possible. We will then

    run multiyear simulations of latent and sensible heat and net ecosystem

    exchange of CO2 at each site with SiB3 using local site meteorlogy and

    vegetation parameters. We will compare the simulated and observed

    seasonality in the three fluxes among sites near Santarem, Manaus, Rondonia,

    and possibly others. We will investigate the influence of seasonal drought

    on gross photosynthesis and respiration, and evaluate model simulation of

    the seasonality of net carbon flux along regional gradients of vegetation

    and of timing, severity, and duration of the dry season.









  1. Analyze

    the two-way interaction between drought and physiological stress in

    Amazonian ecosystems and the implications for possible amplification and

    persistence of regional drought as simulated in the “Amazon catastrophe”

    experiment of Cox et al (2000). Coupled simulations with SiB2 in the CSU GCM

    can reproduce this phenomenon for current climate. We will investigate the

    cause of this phenomenon in the current model, and explore what must be done

    in fully coupled climate simulations to produce such a catastrophe, and what

    model changes are required to avoid it. This work will include local-scale

    simulations and comparison to drought stress observed in the field, as well

    as a range of fully coupled experiments with climate models.









  1. Perform

    a detailed analysis and forward simulation of the Santarém mesoscale

    campaign of July-August 2001 using SiB3/RAMS5. We will compare simulated to

    observed meteorology and tower fluxes at the three Tapajos towers. We will

    focus on the diurnal cycle of sensible and latent heat fluxes and CO2 flux

    at the three towers, diurnal development of the planetary boundary

    layer, its interaction with the regional trade wind circulation, and on

    mesoscale circulations in the presence of topography and rivers. We will

    also compare the time-varying vertical structure of CO2 in and just above

    PBL, and river-land contrasts of mid-morning CO2 on the two days during

    which we collected these data.









  1. Participate

    in a major campaign to be organized in the Tapajos region in 2003 or 2004 to

    investigate the Richey et al hypothesis of major fluxes of CO2 by evasion

    from inundated lands and open waters. We will provide modeling support using

    SiB3 and RAMS to simulate “background” fluxes from terre firme forests

    and pastures, and will also specify evasion fluxes from input obtained from

    collaborators. Our simulations will be used to interpret airborne and

    surface-based continuous measurements of CO2 and other tracers. This

    campaign will be coordinated with members of the Fitzjarrald, Saleska,

    Ehleringer, Bakwin, Melack, and Richey teams.









  1. Perform

    regional inversion analyses of data collected by the COBRA-Brazil field

    campaigns, using SiB3-RAMS and the Lagrangian Particle Dispersion Model

    developed under the previous Cooperative Agreement. This will be carefully

    coordinated with other investigators, and is contingent on the approval of

    the field campaigns in 2003.









  1. Produce

    improved estimates of monthly Basin-wide carbon balance using a global

    atmospheric inversion method similar to the TransCom experiments. This will

    be improved by the inclusion of d13C of CO2 and CO as additional tracers to

    distinguish among biomass burning, C3 photosynthesis from forests and C4

    photosynthesis in pastures and cerrados. The new inversions will also make

    use of new data collected by airborne sampling (Bakwin/Artaxo team),

    continuous surface-based measurements of trace gases by the Saleska and

    Fitzjarrald teams, and isotopic measurements made by the Ehleringer/Ometto

    team.



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