MB-System Unix Manual Page: mbm_bpr

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    mbm_bpr
    Section:  MB\-System 5.0  (1)
    Updated:  3 June 2013
    Index

    NAME

    mbm_bpr - MB-System macro to process data from a Seabird SBE53 pressure
    sensor into a tidal model for use by mbprocess.

    VERSION

    Version 5.0

    SYNOPSIS

    mbm_bpr -Ibprfile -Otidefile [-Doffset Rlon/lat -T -H -V]

    DESCRIPTION

    mbm_bpr is a perl shellscript used to translate pressure data from a Seabird SBE53 pressure
    sensor used as a Bottom Pressure Recorder (BPR) into tidal data that can be used to correct
    swath bathymetry data. The user specifies an input BPR data file in the *.tid format produced
    by Seabird software and the output path for the resulting tidefile.

    By default, the output
    tidefile will be in the form of a text file with two columns:

          time_d tide.

    Here time_d are time values in decimal epoch seconds (seconds since 1970 Jan 1 00:00:00) and the tide values
    are in meters. In this case, the tidefile is in format 1 as supported by mbprocess, so to make use of this
    tide data to correct swath bathymetry, use mbset as follows:

          mbset -Idatalist.mb-1 -PTIDEFILE:tidefilename -PTIDEFORMAT:1

    where datalist.mb-1 is the datalist referring to the data files to be processed. After using mbset to
    turn on tide correction, run mbprocess:

          mbprocess -Idatalist.mb-1

    If the -T option is specified, then the output file will have the form of:

          year month day hour min sec tide

    In this case, the tidefile is in format 2 as supported by mbprocess, so to make use of this
    tide data to correct swath bathymetry, use mbset as follows:

          mbset -Idatalist.mb-1 -PTIDEFILE:tidefilename -PTIDEFORMAT:2

    where datalist.mb-1 is the datalist referring to the data files to be processed. After using mbset to
    turn on tide correction, run mbprocess.

    The macro mbm_bpr calculates depth from pressure and latitude using the empirical formula for seawater in:

            N. P. Fofonoff and R. C. Millard, Jr., Algorithms for computation of fundamental

            properties of seawater, Unesco Tech. Papers in Mar. Sci., No. 44 1983.

    and then calculates tidal data as the difference between the observed depth and a vertical
    reference depth. If a location is supplied using the -R option,
    mbm_bpr uses the latitude in the depth calculation and also extracts a tidal model
    corresponding the to BPR deployment site and timespan using the program mbotps. The vertical
    reference is then the average difference between the tidal model and the observed depths.
    If the user does not supply a location using the -R option,
    a location on the equator is assumed for the depth calculation and the vertical reference is
    the mean depth of the middle half of the depth time series (i.e. depths from 1/4 to 3/4 of the total time span).
    The user can specify an additional offset to apply to the tide data using the -Doffset option.

    If the -T option is not used, then mbm_bpr will also output a shellscript that will, if
    executed, generate a GMT postscript plot of the tide data output. If a location has been specified so that
    a tidal model was also generated, the model will be plotted with the tide data.

    AUTHORSHIP

    David W. Caress (caress@mbari.org)

      Monterey Bay Aquarium Research Institute

    Dale N. Chayes (dale@ldeo.columbia.edu)

      Lamont-Doherty Earth Observatory

    Suzanne H. O'Hara (sohara@ldeo.columbia.edu)

      Lamont-Doherty Earth Observatory

    OPTIONS

    -D

    offset

    An offset to be added to the calculated tidal data, in meters. Default: offset=0.
    -H

    This "help" flag cause the program to print out a description
    of its operation and then exit immediately.
    -I

    bprfile

    Input pressure data from the SBE53 pressure sensor in the Sea-Bird *.tid format.
    -O

    tidefile

    Output tide data file path. The format of the tide data controlled by the use (or not) of the -T option.
    -R

    longitude/latitude

    Sets the location of the BPR deployment. Here longitude and latitude are in decimal
    degrees.
    -T

    Changes the tide data format output. The format of the tide data are normally
    in the form of a text file with two columns:

          time_d tide

    where time_d are time values in decimal epoch seconds (seconds since 1970 Jan 1 00:00:00) and the tide values
    are in meters.
    If the -T option is specified, then the output file will instead have the form of:

          year month day hour min sec tide
    -V

    Causes mbm_bpr to operate in "verbose" mode so that it outputs
    more information than usual.

    Examples

    Suppose one has deployed an SBE53 at 110 deg 40.92220'W 26deg 27.18960'N at about 1200 m depth.
    The Sea-Bird processing software outputs data in *.tid files with output something like:

         1   03/14/2012 16:27:21 99999.9999    20.2731

         2   03/14/2012 16:28:21 99999.9999    20.2696

         3   03/14/2012 16:29:21 99999.9999    20.2589

         4   03/14/2012 16:30:21 99999.9999    20.2537

         5   03/14/2012 16:31:21 99999.9999    20.2448

         6   03/14/2012 16:32:21 99999.9999    20.2322

         7   03/14/2012 16:33:21 99999.9999    20.2188

         8   03/14/2012 16:34:21 99999.9999    20.2656

         9   03/14/2012 16:35:21 99999.9999    20.3567

        10   03/14/2012 16:36:21 99999.9999    20.4316

        11   03/14/2012 16:37:21 99999.9999    20.4929

        12   03/14/2012 16:38:21 99999.9999    20.5661

        13   03/14/2012 16:39:21 99999.9999    20.6242

        14   03/14/2012 16:40:21 99999.9999    20.6891

        15   03/14/2012 16:41:21 99999.9999    20.7590

        16   03/14/2012 16:42:21 99999.9999    19.8901

        17   03/14/2012 16:43:21 99999.9999    18.1037

        18   03/14/2012 16:44:21 99999.9999    17.2487

        19   03/14/2012 16:45:21 99999.9999    15.9275

        20   03/14/2012 16:46:21 99999.9999    14.7406

        21   03/14/2012 16:47:21 99999.9999    13.7798

        22   03/14/2012 16:48:21 99999.9999    13.0540

        23   03/14/2012 16:49:21 99999.9999    12.3869

        24   03/14/2012 16:50:21 99999.9999    11.8464

        25   03/14/2012 16:51:21 99999.9999    11.1999

        26   03/14/2012 16:52:21   528.8065    10.5061

        27   03/14/2012 16:53:21   583.2633     9.9686

        28   03/14/2012 16:54:21   637.7951     9.3547

        29   03/14/2012 16:55:21   693.5947     8.8287

        30   03/14/2012 16:56:21   748.5921     8.3998

        31   03/14/2012 16:57:21   804.0302     8.0251

        32   03/14/2012 16:58:21   859.5471     7.6560

        33   03/14/2012 16:59:21   914.8043     7.3006

        34   03/14/2012 17:00:21   969.7692     7.0322

        35   03/14/2012 17:01:21  1023.0636     6.6673

        36   03/14/2012 17:02:21  1077.7238     6.3327

        37   03/14/2012 17:03:21  1132.0991     6.0528

        38   03/14/2012 17:04:21  1186.9391     5.8203

        39   03/14/2012 17:05:21  1241.4040     5.6089

        40   03/14/2012 17:06:21  1295.6002     5.4167

        41   03/14/2012 17:07:21  1350.1353     5.2188

        42   03/14/2012 17:08:21  1404.8882     5.0195

        43   03/14/2012 17:09:21  1460.2095     4.9215

        44   03/14/2012 17:10:21  1514.6683     4.7630

        45   03/14/2012 17:11:21  1568.9270     4.5651

        46   03/14/2012 17:12:21  1623.3903     4.4452

        47   03/14/2012 17:13:21  1678.6771     4.3075

        48   03/14/2012 17:14:21  1733.7411     4.1910

        49   03/14/2012 17:15:21  1789.1549     4.0284

        50   03/14/2012 17:16:21  1844.5557     3.8760

        51   03/14/2012 17:17:21  1869.8892     3.7976

        52   03/14/2012 17:18:21  1869.8176     3.7534

        53   03/14/2012 17:19:21  1869.8197     3.7088

        54   03/14/2012 17:20:21  1869.8224     3.6828

        55   03/14/2012 17:21:21  1869.8241     3.6682

    where the third column is the pressure in dbar and the fourth column is temperature in degrees C.
    The pressure increases and the temperature decreases as the sensor sinks to the seafloor following
    deployment off a ship. Once the sensor is on the seafloor, pressure variations reflect the tides.

    To extract a tidal model, use mbm_bpr as follows:

        mbm_bpr -I BPR.tid -OBPR.tde -R-110.682037/27.453160 -V

    The output to the shell looks like:

        Program  Status:

          1771 pressure values read from BPR.tid

          Vertical reference to tidal model for position -110.682037 27.453160

          Tide will be output as <time_d tide> values

          A plot will be generated

          Executing: mbotps -A1 -D1200 -R-110.682037/27.453160 -B2012/03/14/16/52/21 -E2012/03/15/22/22/21 -OBPR.tid_tidemodel.txt

          Results are really in BPR.tid_tidemodel.txt

          1690 pressure values output to BPR.tde

          Vertical reference: 1267.31678290355 m

          Executing mbm_xyplot -R1331743941.000000/1331850141.000000/-0.5071/0.5071 -IW0/0/0:BPR.tde -IW255/0/0:BPR.tid_tidemodel.txt -OBPR.tde_tideplot -L"Tide Data from BPR <BPR.tde> (black) & Tide Model (red):Seconds:Tide (meters)" -V

          Executing <BPR.tde_tideplot.cmd> also invokes gv to view the plot on the screen.

    The output tidal data file BPR.tde has the form:

        1331745441.000000 -0.0803109226781089

        1331745501.000000 -0.129052283649798

        1331745561.000000 -0.127622718432121

        1331745621.000000 -0.125784706023751

        1331745681.000000 -0.124627438960488

        1331745741.000000 -0.123334022838208

        1331745801.000000 -0.12285750111073

        1331745861.000000 -0.121768308595847

    where the first column is time in seconds since January 1, 1970 (epoch seconds, aka unix
    seconds, aka time_d values within MB-System), and the second column is the tidal signal
    in meters. In this case the reference tidal model is provided by mbotps, and the
    plot created by running the output shellscript BPR.tde_tideplot.cmd plots both the tidal data
    calculated by mbm_bpr and the tidal model extracted using mbotps.

    SEE ALSO

    mbsystem(1), mbprocess(1), mbset(1)

    REFERENCES

    N. P. Fofonoff and R. C. Millard, Jr., Algorithms for computation of fundamental
    properties of seawater, Unesco Tech. Papers in Mar. Sci., No. 44 1983.

    BUGS

    Lobsters, really.

     Index

    NAME
    VERSION
    SYNOPSIS
    DESCRIPTION
    AUTHORSHIP
    OPTIONS
    Examples
    SEE ALSO
    REFERENCES
    BUGS

Last Updated: 3 June 2013

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