1.

Ameriflux is a program designed to investigate the source of the unknown carbon sink of atmospheric carbon dioxide in the biosphere. To achieve this end, carbon dioxide and water vapor flow between flora and the atmosphere is measured and analyzed using sonic anemometers and infrared gas analyzers and the eddy-covariance method over the long-term.

Table 2. Recommended core and desired Meteorological and Flux Measurements to be carried out at each AmeriFlux site.

I. EDDY FLUX DENSITIES

    A. CORE MEASUREMENTS
1. sensible heat
2. latent heat (evapotranspiration)
3. CO2
4. momentum

    II. STORAGE FLUXES

A. CORE MEASUREMENTS
    1. CO2 storage in canopy air layer (CO2 profile)

B. DESIRED MEASUREMENTS
    1. heat storage in canopy air (temperature profile)

    III. SOIL FLUXES

A. CORE MEASUREMENTS
    1. CO2 flux
    2. heat flux

B. DESIRED MEASUREMENTS
    1. water vapor flux

    IV. METEOROLOGY

A. CORE MEASUREMENTS
    1. air temperature (ventilated shielded)
    2. net radiation
    3. global radiation or photosynthetically active photon flux density (PPFD)
    4. RH, or dewpoint temperature or wet bulb temperature
    5. precipitation
    6. wind speed and direction

B. DESIRED MEASUREMENTS
1. diffuse radiation or PPFD
2. absorbed PPFD
3. longwave radiation
4. canopy wetness
5. pressure
 

2) understand the biological and climatic processes that control canopy scale CO2 and water vapor exchange;

3) test carbon balance and hydrological models;

4) improve the ability of models to simulate seasonal dynamics (e.g., tune phenological switches that initiate budbreak, grow leaves and initiate leaf senescence);

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