Appendix A. EasyFlux DL CR6CP Process Flow
A-3
If using self-calibrating heat flux plates and a new calibration interval
has started, perform the auto calibration
⇩
If station variables have changed, save new values to memory
⇩
System power control (if needed, power down gas analyzer and pump)
⇩
Temp control for valve and scrub modules
⇩
If a zero/span has completed, save new gain and offset values and
store zero/span outputs to ZeroSpan_Check_Notes and EC100_config
_Notes tables
Every 5 Minutes
Do coordinate rotations and find the 5-minute covariances for u with w,
v with w, Ts with w,
CO
2
with w, and
H
2
O
with w (used later for steady
state test for quality grading; see Appendix F in
EasyFlux DL CR6OP
manual on Data Quality Grading for more details)
.
Every AVERAGING_INTERVAL (default 30 minutes)
Filter out data with diagnostic flags or signal strengths or
measurements outside of acceptable ranges.
⇩
Do coordinate rotations (use double coordinate rotation method unless
planar fit angles have been entered by user) to find rotated orthogonal
wind components,
u
,
v
, and
w.
Calculate sonic-related covariances
(e.g., wTs, wu, vw). (See
EasyFlux DL CR6OP
manual, Appendix B on
Double Coordinate Rotation and Appendix C on Planar Fit Rotation.)
⇩
Use rotated wind components to find turbulent kinetic energy, friction
velocity, and preliminary values of Obukhov length and stability.
⇩
Calculate frequency correction factors for wTs, wu, and vw to account
for block averaging and line averaging. If conditions are stable,
iteratively calculate Obukhov length, cospectral equations, and
correction factors until factors change by <0.0001 or until 10 iterations
have completed. (See in
EasyFlux DL CR6OP
manual, Appendix D on
Frequency Corrections.)