Campbell CPEC300, Руководство по эксплуатации продукта

Страница: 88 / 175

CPEC300/306/310 Closed-Path Eddy-Covariance Systems
79
TABLE 6-14. Data Field in the System_Operatn_Notes Output Table
Data Field Name Units Description Data Field Included
Message
Text
string
A message describing a change of system
status
Always
Current Value
Text
string
Additional information corresponding to the
Message
Always
Previous Value
Text
String
Additional information corresponding to the
Message
Always
6.6 Program Sequence of Measurement and Corrections
The main correction procedures and algorithms implemented into the program
are listed below. For a more detailed, stepwise description of measurements
made and corrections applied, refer to Appendix A , EasyFlux DL CR6CP
Process Flow
(p. A-1)
.
1. Despike and filter raw time series data using sonic and gas analyzer
diagnostic codes, and signal strength and measurement output range
thresholds.
2. Coordinate rotations with an option to use the double rotation method
(Tanner and Thurtell 1969), or planar fit method (Wilczak et al.
2001).
3. Lag CO
2
and H
2
O measurements relative to sonic wind measurements
for maximization of CO
2
and H
2
O covariances (Horst and Lenschow
2009, Foken et al. 2012), with additional constraints to ensure lags are
physically possible.
4. Frequency corrections using commonly used cospectra (Moore 1986,
van Dijk 2002a, Moncrieff et al. 1997) and transfer functions of block
averaging (Kaimal et al. 1989), line/volume averaging (Moore 1986,
Moncrieff et al. 1997, Foken et al. 2012, van Dijk 2002a), time
constants (Montgomery 1947, Shapland et al. 2014, Geankoplis
1993), sensor separation (Horst and Lenschow 2009, Foken et al.
2012), and tube attenuation (Ibrom et al. 2007, Burgon et al. 2016).
5. A modified SND correction (Schotanus et al. 1983) to derive sensible
heat flux from sonic sensible heat flux following the implementation
as outlined in van Dijk 2002b. Additionally, fully corrected real
sensible heat flux computed from fine-wire thermometry may be
provided.
6. Data quality qualifications based on steady state conditions, surface-
layer turbulence characteristics, and wind directions following Foken
et al. 2012 (or Foken et al. 2004 for the Flux_AmeriFluxFormat
output table).
7. If energy balance sensors are used, calculation of energy closure based
on energy balance measurements and corrected sensible and latent
heat fluxes.