Instruction manual

3-1
SECTION 3. SAMPLE 21X PROGRAM
This section provides a sample program that may be used to measure the eddy covariance sensors and
the auxiliary sensors. The CA27, 127, and KH20 are measured in Table 1 at 5 Hz. The meteorological
sensors and the energy balance sensors are measured in Table 2 at 0.5 Hz. The meteorological
sensors include wind speed, wind direction, air temperature, and vapor pressure. The energy balance
sensors include net radiation, soil heat flux soil temperature, soil water content, and change in soil
temperature. Note that even if this exact installation is used, the correct multipliers must be entered for
the net radiometer and soil heat flux plate.
The execution interval in Table 1 may be changed to 0.1 (10 Hz). For most flux studies the increased
sample rate does not add any significant statistical information about the turbulent fluxes. It does,
however, increase the current drain of the datalogger and cause Table 1 to overrun every ten minutes
when the subinterval averages are calculated. If the execution interval is changed to 0.1, the seventh
parameter in the twelfth instruction (P62) must be changed to 6000.
To conserve battery power and extend the life of the krypton hygrometer tubes, disconnect the CA27
and KH20 from the battery when measurements are not being made, e.g., during a rain shower. During
a rain shower or other inclement weather, shut down and cover the eddy correction system with plastic
bags (see Section 1.3.1 for details).
Set flag 1 high to disable averaging while cleaning the KH20 windows and performing other station
maintenance. Set flag 1 low to resume averaging.
;{21X}
;
;c:\dl\ec\ecsep96.csi
;5 September 1996
;
*Table 1 Program
01: 0.2 Execution Interval (seconds)
01: If Flag/Port (P91)
1: 22 Do if Flag 2 is Low
2: 2 Call Subroutine 2
02: Volt (Diff) (P2)
1: 3 Reps
2: 15 5000 mV Fast Range
3: 1 In Chan
4: 1 Loc [ w ]
5: 1 Mult
6: 0 Offset
03: Z=X*F (P37)
1: 1 X Loc [ w ]
2: .001 F
3: 1 Z Loc [ w ]
04: Z=X*F (P37)
1: 2 X Loc [ T ]
2: .004 F
3: 2 Z Loc [ T ]
;Move new signal before natural log.