INSTRUMENTATION

The eddy covariance system consisted of a fast-response closed-path infra-red gas analyser to measure carbon dioxide and water vapour (Li 6262, Li-Cor, Lincoln, Nebraska); a 3-dimensional sonic anemometer to measure the vertical component of wind (Solent A1002R, Gill Instruments, Lymington, UK); a pumping unit to draw air through 5m of 5.5 mm diameter tubing (Dekabon 1300, Deane & Co., Glasgow, UK); and a 386 laptop' computer with software EDDYSOL' to enable the flux calculations to be made as half-hour averages in real time (Moncrieff et al. 1996, Grace et al. 1995)

The data columns are as follows:

Year

Day number

Local Time (hours)

Local Time (minutes)

N.B. Local Time = GMT-4 hours. The time stated is the time at the END of each half-hour period

Sensible Heat Flux (W/m2)

Evaporation (mmol/m2/s)

N.B. These H and E fluxes have been compared with those of the coincident micrometeorology system (Wright et al 1996) and used in deriving the agreed fluxes which are contained in FORSTM3.DAT and FORSTM45.DAT (FORST.EXE). Therefore, the fluxes given here should only be considered as raw output from this system, and only the FORST' files should be used as the best estimate of latent and sensible heat flux from this site.

CO2 turbulent flux (mmol/m2/s)

Friction velocity (m/s)

Standard deviation of u-component of wind velocity

Standard deviation of v-component of wind velocity

Standard deviation of w-component of wind velocity

Mean value of u (m/s)

u positive is wind GOING IN the direction 224 degrees

Mean value of v (m/s)

v positive is wind GOING IN the direction 314 degrees

Mean value of w (m/s)

w positive is wind GOING UPWARDS

Mean virtual temperature from sonic anemometer (K)

Mean CO2 concentration (parts per million)

Mean H2O concentration (parts per thousand)

Mean tube lag on CO2 measurements

(in units of 1/20.8 secs)

Mean tube lag on H2O measurements

(in units of 1/20.8 secs)

The following 4 columns appear in AB-ROND93.DAT only

Mean within-canopy CO2 concentration

Mean within-canopy CO2 storage flux

(positive = flux OUT of canopy)

Mean above-canopy wind speed

Mean Monin-Obukhov length, L

REFERENCES

Grace, J., Lloyd, J., McIntyre, J., Miranda, A.C., Meir, P., Miranda, H.S., Moncrieff, J., Massheder, J., Wright, I.R. and Gash, J.H.C., 1995. Fluxes of carbon dioxide and water vapour over an undisturbed tropical rain forest in south-west Amazonia. Global Climate Change, 1: 1-12.

Moncrieff, J.B., Massheder, J.M., Verhoeh, A., Elbers, J., Heusinkveld, B., Scott, S., de Bruin, H., Kabat, P. and Jarvis, P.G., 1995. A system to measure surface fluxes of energy momentum and carbon dioxide. J. Hydrol. In Press.

Wright, I.R., Gash, J.H.C.G., da Rocha, H.R. and Roberts, J.M., 1995. Modelling surface conductance for Amazonian pasture and forest. In Amazon Deforestation and Climate (Eds. J.H.C. Gash, C.A. Nobre, J.M. Roberts and R.L. Victoria), John Wiley,Chichester. pp 437-458.