Robert J. Zamora Co PI NOAA/ESRL/Physical Science Division 
March 24, 2006
Direct turbulent fluxes from the 2004 NAME site at Estacion Obispo, MX
Latitude: 24.280 N, Longitude: -107.16 W, Elevation 27.0 m (ASL)
Version 1 IDL Code by William Otto
The data file contains computations of fluxes derived by the Physical Sciences
Division of the NOAA Earth System Research Laboratory.
Direct (covariance) turbulent flux calculations are included in this data set.
The data file, NAME_2004_turbulent_flux_dat is a comma delimited ASCII file.
There are eight fields in each data record.

Field 1: Year, Julian day, and time (UTC) of the start of the averaging period.
Example: 41952100, Year=2004, Julian day=195, Time=2100 UTC.
Field 2: Mean wind direction for the averaging period from sonic anemometer (deg).
Field 3: Mean wind speed for the averaging period from sonic anemometer (m/s).
Field 4: Covariance streamwise uw, sonic anemometer (m^2/s^2).
Field 5: Covariance cross-stream vw, sonic anemometer (m^2/s^2).
Field 6: Sensible heat flux, sonic anemometer (W/m^2).
Field 7: Latent heat flux, (W/m^2) (includes Webb et al. correction)
Field 8: CO2 flux, (micatm m/s)

Missing data flag = -9999.99999

The data in this file comes from two sources: 
An Applied Technologies Inc. Sonic Anemometer/Thermometer Model SATI/3K sampled
at 20 Hz and a LICOR 7500 open path IR gas analyzer sampled at 20 Hz.
The sonic anemometer was mounted at the 9.2 meter level of the tower.
The LICOR 7500 was mounted at the 8.7 meter level of the tower.

Turbulent fluxes were computed from time series of fast sensor data. Covariance
latent heat fluxes were obtained by cross-correlating vertical velocity with
fast humidity fluctuations from the LICOR 7500.
The displacement vector between the midpoint of the LICOR 7500 open path 
and the midpoint of the ATI sonic anemometer z-axis was 51.0 cm.
No corrections for covariance loss were applied to the latent heat flux
calculations. CO2 fluxes were obtained by cross-correlating vertical velocity with
fast CO2 fluctuation from the LICOR 7500. Again, no covariance loss corrections 
were applied to the CO2 fluxes.

In general the flux calculations follow the steps described by:
Persson et al. Journal of Geophysical Research Vol. 107, NO. C10, 8045,
doi:10.1029/2002JC000705, 2002.

The latent heat fluxes measured at this site under certain conditions may be
influenced by evaporation from the surface of the Gulf of California which is
located 20 km to the southwest of the flux tower.