Altimetry or Bathymetry File
The format is the same for top altimetry or bottom bathymetry. Only
BELLHOP and SimplePE use these files. (SimplePE allows bathymetry
variations, but not altimetry variations.)
Syntax:
TYPE
NPOINTS
R(1) Z(1)
R(2) Z(2)
.
.
.
R(NPOINTS) Z(NPOINTS)
Description:
TYPE(1:1)
'L' for piecewise linear
'C' for curvilinear
TYPE(2:2)
'S' Short format (bathymetry only) (default)
'L' Long format (bathymetry and geoacoustic
parameters)
NPOINTS: Number of r-z
points to follow.
R():
Range (km)
Z():
Depth (m).
Example (bathymetry only):
'L'
5
0 3000
10 3000
20 500
30 3000
100 3000
Example (bathymetry and geoacoustics):
'LL'
3
0 100 1700 0.0 1.2 0.5 0
2.5 100 1550 0.0 1.2 0.5 0
5.0 100 1550 0.0 1.2 0.5 0
Generally the piecewise linear option should be selected. However,
if the boundaries are sampled on a very fine scale (a few
wavelengths) then the curvilinear option produces a smoother fit.
That in turn improves the results obtained with geometric ray
tracing. The curvilinear option was implemented to treat effects of
fine-scale scattering.
Note that depths, z, are positive downward,
following a convention used throughout the models. This
is a bit counter-intuitive for altimetry; however, a
different convention for that would also have been
counter-intuitive for others.
The vector of range values must increase strictly
monotonically.
The second letter of the TYPE string is used to select a
range-dependent bottom type. If you set it 'L'
additional entries will be read with that geoacoustic
information given in the same format as used for
halfspaces in the environmental file (compressional wave
speed, compressional wave attenuation, density,
shear wave speed, shear wave attenuation).