LI-COR LI7200RS, Инструкция по эксплуатации

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About Data Files
Eddy covariance data files (.ghg extension) are ASCII text files with a header and
tab-delimited rows of data. When paired with the metadata file, the data file header
is ignored by EddyPro, which uses the metadata file to interpret the data columns
and to retrieve the appropriate meta-information needed to calculate fluxes. The
metadata information is stored as plain text, and can be retrieved and edited as
desired. Typical metadata includes information such as site and setup, the instru-
ments, and the variable definitions, including physical units.
About File Compression (USB Logging Only)
CO
2
/H
2
O measurements, wind speed measurements, CH
4
measurements (with the
LI-7700), Biomet measurements (with the Biomet System) and site metadata are
logged in a compressed archive if you click the ‘Compress files (.ghg)’ check box.
Files are typically compressed at a ratio of about 4:1 (can be as high as 10:1, depend-
ing on file attributes). As an example, if the LI-7500DS, LI-7200RS or LI-7500RS
and LI-7700 CH
4
Analyzer are both logging data at 20 HZ, with 53 columns of
data, a one hour file would be approximately 30 MB uncompressed, and 7 MB com-
pressed, for an approximate 4x compression ratio.
File compression is essential to log .ghg files that are processed in EddyPro software
or the SmartFlux System. The .ghg file contains an archive consisting of the data
file (.data extension), a metadata file (.metadata extension), and an optional LI-7700
status file (.status extension).
When file compression is enabled, an archive is created and the file name is appen-
ded with a .ghg file extension. To view the contents of a .ghg file, you can change
the file extension to .zip and unzip it with the extraction tool included with Win-
dows® or unzip the .ghg file using a program such as 7-zip.
Files are saved and compressed after the
File Duration
interval has elapsed. If the file
duration is set to 15 minutes, the first .data file will be collected for 15 minutes (or
some part thereof), after which it will be compressed, and the second data file will
commence for 15 minutes, after which it is compressed, and so on.
Note: If the file duration is set to
Continuous
, files will not be compressed.
Section 3. Operation
3-45 About Data Files