Turnipseed_FluxData Instructions

Investigator: Andrew Turnipseed, NCAR/ACD
turnip@ucar.edu

Filename:  Turnipseed_ROMBAS_FluxData.csv (comma delimited)

Data Interval:  15 min. averages
Initial Start time of file:  July 1, 2011, 0:00:00  (MST)
Measurement height:  25.1 m (height of sonic anemometer and inlet for CO2/H2O)
Missing data = -9999

Columns:
Start_sec:	Beginning of 5 min. period  (seconds since July 1, 2011, 0:00:00 MST)
End_sec: 	End of 5 min. period  (seconds since July 1, 2011, 0:00:00 MST)
Mid_sec:	Midpoint of 5 min. period  (seconds since July 1, 2011, 0:00:00 MST)
Date:		MM/dd/YY, 
Time:		hh:mm:ss, Beginning of 5 min. period (MST)
Day of Year:	decimal day, Beginning of 5 min. period (MST)
Wspd:		Scalar-averaged Wind speed, units = m/s, z = 25.1 m
v-Wspd:		Vector-averaged Wind speed, units = m/s, z = 25.1 m
WD:		Wind Direction, units = degrees from North, z = 25.1 m
s(WD):		Standard deviation of the wind direction, units = degrees from North, z = 25.1 m
z/L:		Measurement height/Obukhov Length, unitless, measure of atm. stability, z = 25.1 m
u*:		Friction Velocity, units = m/s, z = 25.1 m
H:		Sensible Heat flux, units = W/m^2, z = 25.1 m
LE:		Latent Heat flux (water vapor), units = W/m^2, z = 25.1 m
w'q':		Water vapor flux, units = mmol m-2 s-1, z = 25.1 m
F(co2):		CO2 flux, units = micromol m-2 s-1, z = 25.1 m


Instrumentation:
Wind Velocities:		Campbell Scientific CSAT-3 sonic anemometer		
CO2/H2O:			Licor Li7000 IR gas analyzer
Logging:			Labview program  

Analysis Notes:
(1) Wind velocities were rotated into long-term mean streamline coordinates via the planar fit method
before computation of covariances (fluxes).
(2) All time series were linearly detrended and despiked prior to analysis.
(3) Lag times between scalar concentrations (CO2, H2O) and wind velocities were determined via
the peak of the cross correlation spectrum for each scalar and the time series were adjusted 
in time according to this lag before covaraince computation.
(4) CO2 fluxes were corrected for water vapor density fluctuations according to Webb et al., 1980 
(WPL corrections).