flux_YYYY.txt - computed fluxes, -999.000 for missing
  Year - year
  MO - two digit month
  DD - two digit day of month
  HH - two digit hour of day (most are UTC, except prefnee in CST)
  DOY - Day of Year (1-366)
  fDOY - Day of year fraction (1.0-366.958)
  NEE_30 - Net Ecosystem Exchange at 30 m in umol m-2 s-1
  LE_30 - Latent heat flux at 30 m in W m-2
  H_30 - Sensible heat flux at 30 m in W m-2
  u*_30 - Friction velocity at 30 m in m s-1
  same for _122 at 122 m
  same for _396 at 396 m

cal_YYY.txt - calibration coefficients - don't worry about this file for now
  B and M are intercept and slope for calibration fits for CO2 (C) and H2O (Q) signals, for the 5 levels (30m, 122m, 396m trailer, 
and 122m and 396m in situ)

diag_YYYY.txt - diagnostics - again don't worry for the moment, but lots of variables that could be useful for sleuthing, 
including storage fluxes, lag times, spectral corrections, mixing ratios, air densities, etc...  e.g:
  FLAG1-5 not used at the moment
  Cstor_30 = storage of CO2 below flux sensor at 30 m in ppm m s-1
  Qmix - mixing ratio

met_YYYY.txt - hourly average meteorological data (there is also one minute average data in another directory if we need it)
Year, MO, DD, HH, DOY, fDOY - same as flux_YYYY
CO2_xx = CO2 concentration in ppm at 30,122,396 m
Uxx = mean wind speed in m s-1 at 30,122,396 m
Udirxx = mean wind direction in degrees
Txx = mean air temperature in degrees C
RHxx = mean relative humidity in percent
Qxx = mean water vapor mixing ratio in g kg-1
Patm = atmospheric pressure at tower base in kPa
Precip = total hourly precipitation in mm
PAR = incoming photosynthetic active radiation (PAR) in umol m-2 s-1

prefnee_YYYY.txt - first cut preferred/gap filled NEE (we combine the three levels using an algorithm and fill using regression)
Year, MO, DD, HH, DOY, fDOY - same as flux_YYYY
prefNEE - preferred NEE in umol m-2 s-1
prefLE - latent heat flux W m-2
prefH - sensible heat flux W m-2
prefflag - -1.0 for missing data, else which height are we using
fillNEE - gap-filled NEE based on u* screening and Cook-Desai gap-filling method
GPP - model estimate of gross primary productivity in umol m-2 s-1
RE - model estimate of ecosystem respiration
modNEE - model estimate of NEE used in fillNEE
Temp - gap-filled temperature used in model regression (usually 30 m)
PAR - gap-filled PAR used in model regression
Precip - total precipitation
CO2 - mean CO2 concentration at 30 m
U - wind speed in m s-1 at 30 m
Udir - wind direction in degrees at 30 m