Read an RBR rsk or txt file, e.g. as produced by an RBR logger, producing an
object of class
1 2 3 4 5 6 7 8 9 10 11
a connection or a character string giving the name of the file to
load. Note that
indication of the first datum to read. This can a positive integer
to indicate sequence number, the POSIX time of the first datum, or a character
string that can be converted to a POSIX time. (For POSIX times, be careful
an indication of the last datum to be read, in the same format as
an indication of the stride length to use while walking through the
file. If this is an integer, then
optional file type, presently can be
time zone. The value
controls the handling of atmospheric pressure, an important issue for RBR instruments that record absolute pressure; see “Details”.
if provided, the action item to be stored in the log. This is typically only provided for internal calls; the default that it provides is better for normal calls by a user.
a flag that can be set to
This can read files produced by several RBR instruments. At the moment, five
styles are understood: (1) text file produced as an export of an RBR
rsk file; (2) text file with columns for temperature and pressure
(with sampling times indicated in the header); (3) text file with four columns,
in which the date the time of day are given in the first two columns, followed
by the temperature, and pressure; (4) text file with five columns, in which
depth in the water column is given after the pressure; (5) an SQLite-based
database format. The first four options are provided mainly for historical
reasons, since RBR instruments at the date of writing commonly use the SQLite
format, though the first option is common for all instruments that produce a
hex file that can be read using Ruskin.
Options 2-4 are mostly obsolete, and will be removed from future versions.
A note on conductivity. RBR devices record conductivity in mS/cm, and it
is this value that is stored in the object returned by
read.rsk. This can
be converted to conductivity ratio (which is what many other instruments report)
by dividing by 42.914 (see Culkin and Smith, 1980) which will be necessary in
any seawater-related function that takes conductivity ratio as an argument (see
A note on pressure. RBR devices tend to record absolute pressure (i.e.
sea pressure plus atmospheric pressure), unlike most oceanographic instruments
that record sea pressure (or an estimate thereof). The handling of pressure
is controlled with the
patm argument, for which there are three
possibilities. (1) If
FALSE (the default), then
pressure read from the data file is stored in the
data slot of return
value, and the
pressureType is set to the string
"absolute". (2) If
TRUE, then an estimate of
atmospheric pressure is subtracted from the raw data. For data files in the
SQLite format (i.e.
*.rsk files), this estimate will be the value read
from the file, or the “standard atmosphere” value 10.1325 dbar, if the file
lacks this information. (3) If
patm is a numerical value (or list of
values, one for each sampling time), then 'patm' is subtracted from the
raw data. In cases 2 and 3, an additional column named
'pressureOriginal' is added to the 'data' slot to store the value
contained in the data file, and 'pressureType' is set to a string
starting with '"sea"'. See
as.ctd() for details of how this
setup facilitates the conversion of rsk objects to
An rsk object.
Dan Kelley and Clark Richards
Culkin, F., and Norman D. Smith, 1980. Determination of the concentration of potassium chloride solution having the same electrical conductivity, at 15 C and infinite frequency, as standard seawater of salinity 35.0000 ppt (Chlorinity 19.37394 ppt). IEEE Journal of Oceanic Engineering, 5, pp 22-23.
The documentation for rsk explains the structure of
rsk objects, and also outlines other functions dealing with them. Since
RBR has a wide variety of instruments,
rsk datasets can be quite general,
and it is common to coerce
rsk objects to other forms for specialized
as.ctd() can be used to create CTD object, so that the
generic plot obeys the CTD format.
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