Campbell EC155, Руководство по эксплуатации продукта

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EC155 CO
2
and H
2
O Closed-Path Gas Analyzer
48
For the CSAT3A, refer to the CSAT3A instruction manual for information on
recalibration.
10. Data Collection and Data Processing
Data from the EC155 is collected through the EC100 and then archived onto a
datalogger. A common instrument configuration is to program a datalogger to
retrieve and collect raw data from the EC155, to be used for post processing,
for which various programs have been developed.
More recently, programs have been developed that efficiently record and
correctly process data from instruments such as the EC155, as well as compile
them with data from other, complementary instruments. Campbell Scientific
has developed a program, EasyFlux™ DL, that both records and processes raw
data from the EC155 to provide useful measurements immediately. An
overview of both approaches is given in the sections below.
10.1 Data Collection and Processing with
EasyFlux DL
EasyFlux DL is an open source CRBasic program that allows a CR6 or
CR3000 datalogger to collect fully corrected measurements from an EC155
instrument. The program is compatible with other GPS and energy balance
sensors which, in combination, can report corrected fluxes for CO
2
, latent heat
(H
2
O), sensible heat, ground surface heat flux, and momentum. The program
processes the EC data using commonly used corrections in the scientific
literature. For detailed information about downloading, installing, and
configuring the free program, refer to the
EasyFlux DL
manual located at
www.campbellsci.com/easyflux-dl .
Of particular note is the manner in which EasyFlux DL processes information
from the sonic anemometer and is useful to understand when considering how
to situate the analyzer and anemometer at a given site.
EasyFlux DL reports the wind direction in both the sonic coordinate system (a
right-handed coordinate system, FIGURE 10-1 ) and in the compass coordinate
system (a left-handed coordinate system, FIGURE 10-2 ). To report the wind
direction in the compass coordinate system, the orientation of the sonic must be
known. The sonic coordinate system is relative to the sonic itself and does not
depend on the sonic’s orientation. The compass coordinate system is fixed to
Earth. For the EasyFlux DL program to compute the correct compass wind
direction, the azimuth of the sonic negative x-axis must be entered into the
program. The output value for the compass coordinate system is WD and the
output value for the sonic coordinate system is WD_Sonic . The program
default value for the variable sonic_azimuth is 0 . To report a true compass
wind direction, an appropriate value for sonic_azimuth must be entered into
the program. The default is appropriate only if the sonic is mounted such that
the negative x-axis points to the north.
Remember to account for magnetic declination at the installation
site. See Appendix D , CSAT3A Orientation
(p. D-1)
for details.
The variable sonic_azimuth can be changed in LoggerNet or by using a
CR100KD keypad. It can be changed in LoggerNet by connecting the
datalogger to a computer, opening
LoggerNet
, and going into the Public data
NOTE