LOADCOMB(1)

NAME
loadcomb - combines and scales load tide files

SYNOPSIS
loadcomb c [scale (amp) scale (phase)] [rotation]

loadcomb b [rotation]

loadcomb t [scale (amp) scale (phase)] [rotation]

loadcomb r [scale (amp) scale (phase)] [rotation]

DESCRIPTION

Loadcomb performs operations on load-tide files (as written by nloadf and concatenated), read from the standard input, and writes the results to the standard output. The options are:

c   takes two load files, concatenated together with the cat command, and adds the load values in them. The header lines from each file are included in the output, except that the ``station'' line is taken to be that from the first file. If two numerical arguments are given on the command line, they are taken to be the amplitude and phase of a (complex) scaling factor that is applied to the loads in the second file before doing the addition. If a single numerical argument is present, it is taken to be the amount by which the reference frame is rotated from the ``standard'' one; this is equivalent to giving the direction (clockwise from East) along which the loads are to be given. An argument of 0 would thus give the loads in the original system; for one of 90 [degrees] (for example) the displacements would be given, in order, as South, West, and Up. If three numerical arguments are given, they are taken to be the scaling (applied to the second file) followed by a rotation (applied to the sum). If a rotation or scaling is performed, additional ``header lines'' (with initial letter R) are written to the load file to indicate this.

r   takes a single load file and applies the scaling (and/or rotation) as specified for the previous option; additional header lines are added.

b   using the first two lines of the load file, gets the station location and tidal constituent, and from these computes the body tides at this location, assuming a spherical Earth with Love numbers h = 0.6114, k = 0.3040, and l = 0.0832, and the Cartwright-Tayler constituent amplitudes. The file output includes a ``model'' line which indicates that the tides given are the body tides. The results may be given rotated to be along any azimuth, as with the previous two cases; a header line is added to show this.

t   operates as with the b option, except that the load tides read in are added to the body tides to give the total tides. The load tide may be scaled, or the sum may be rotated, as with the previous cases; header lines are added to show this.

EXAMPLES

cat loadfile1 loadfile2 loadcomb c

cat loadfile1 loadfile2 | loadcomb c 1.3 -10

cat loadfile1 | loadcomb b

cat loadfile1 | loadcomb t 45

cat loadfile1 | loadcomb r 45

cat loadfile1 | loadcomb r 10 -5

The first line shows the most usual use: adding the results already computed in the two loadfiles. The second line shows the same, with the loads in the second loadfile being scaled by 1.3 in amplitude and shifted by -10° in phase. The third line will produce the body tides at the location given by loadfile1; the fourth line, the total (body and load) tides at the same location, in a reference frame rotated by 45° (so the 1-axis points SE). The fifth line will rotate the loads by 45°; the sixth line will scale the loads by a factor of 10, with a -5° phase shift.

SEE ALSO
harprp(1), which may be used to compute the strains and tilts at a particular azimuth.

AUTHOR
D. C. Agnew