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    <h1 style="font-family: monospace;">Description of Environmental
      File</h1>
    <h3 style="margin-left: 40px; font-family: monospace;"><o:p><a
          href="#1_-_Title">1. Title</a></o:p></h3>
    <h3 style="margin-left: 40px; font-family: monospace;"><o:p><a
          href="#2_-_Frequency">2. Frequency</a></o:p></h3>
    <h3 style="margin-left: 40px; font-family: monospace;"><o:p><a
          href="#3_-_Number_of_Media_">3. Number of Media</a></o:p></h3>
    <h3 style="margin-left: 40px; font-family: monospace;"><o:p><a
          href="#4_-_Options">4. Top Option</a></o:p></h3>
    <h4 style="margin-left: 80px; font-family: monospace;"><a
        href="#4a_-_Top_Halfspace_Properties_">Top Halfspace Properties</a></h4>
    <h4 style="margin-left: 80px; font-family: monospace;"><a
        href="#4b_-_Top_Reflection_Coefficient_">Top Reflection
        Coefficient</a></h4>
    <h4 style="margin-left: 80px; font-family: monospace;"><a
        href="#4c_-_Twersky_Scatter_Parameters_">Twersky Scatter
        Parameters</a></h4>
    <h3 style="margin-left: 40px; font-family: monospace;"><o:p><a
          href="#5a_-_Sound_Speed_Profile_">5. Sound Speed Profile<br>
        </a></o:p></h3>
    <h3 style="margin-left: 40px; font-family: monospace;"><a
        href="#6_-_Bottom_Option_">6. Bottom Option</a></h3>
    <h4 style="margin-left: 80px; font-family: monospace;"><a
        href="#6a_-_Bottom_Halfspace_Properties_">Bottom Halfspace
        Properties</a></h4>
    <h4 style="margin-left: 80px; font-family: monospace;"><a
        href="#6b_-_Bottom_Reflection_Coefficient_">Bottom Reflection
        Coefficient</a></h4>
    <p style="font-family: monospace;" class="MsoPlainText"><o:p>&nbsp;</o:p></p>
    <p style="font-family: monospace;" class="MsoPlainText">The
      following can be repeated as many times as wanted in a single
      ENVFIL. KRAKEN and KRAKENC will generate a separate MODFIL for
      each case stopping when it detects an end-of-file.</p>
    <p style="font-family: monospace;" class="MsoPlainText"><o:p><br>
      </o:p></p>
    <h3 style="font-family: monospace;"><a name="1_-_Title"></a>(1) -
      Title</h3>
    <div style="margin-left: 40px; font-family: monospace;">Syntax:</div>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span><var>TITLE</var></p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Description:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>TITLE: Title of run
      enclosed in sinqle quotes.</p>
    <p style="font-family: monospace;" class="MsoPlainText"><o:p><br>
      </o:p></p>
    <h3 style="font-family: monospace;"><a name="2_-_Frequency"></a>(2)
      - Frequency</h3>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Syntax:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span><var>FREQ</var></p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Description:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>FREQ: Frequency in Hz.</p>
    <p style="font-family: monospace;" class="MsoPlainText"><o:p><br>
      </o:p></p>
    <h3 style="font-family: monospace;"><a name="3_-_Number_of_Media_"></a>(3)
-
Number







      of Media<br>
    </h3>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Syntax:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span><var>NMEDIA</var><br>
    </p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Description:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>NMEDIA: Number of
      media.</p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText">The problem is divided into media within
      which it is<span style=""> </span>assumed that the material
      properties vary smoothly. A new<span style=""> </span>medium
      should be used at fluid/elastic interfaces or at<span style=""> </span>interfaces
where
the







      density changes discontinuously. The<span style=""> </span>number
      of media in the problem is defined excluding the<span style=""> </span>upper







      and lower half-space.<br>
      <o:p></o:p></p>
    <div style="margin-left: 40px; font-family: monospace;">
      <p>BELLHOP is limited to one medium (NMEDIA=1) and actually
        ignores this parameter.</p>
    </div>
    <p style="font-family: monospace;" class="MsoPlainText"><o:p></o:p></p>
    <p style="font-family: monospace;" class="MsoPlainText"><o:p><br>
      </o:p></p>
    <h3 style="font-family: monospace;"><a name="4_-_Options"></a>(4) -
      Top Option</h3>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Syntax:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span><var>TOPOPT</var></p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Description:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>TOPOPT(1:1): Type of
      interpolation to be used for the SSP.</p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>'C' for C-linear,<br>
      <span style=""></span>'N' for N2-linear (n the index of
      refraction),<br>
      <span style=""></span>'S' for cubic Spline,<br>
      'Q' for Quadrilatteral 2D SSP (BELLHOP&nbsp;&nbsp; only; reads the
      SSP from a file)<br>
      'H' for Hexahedral&nbsp;&nbsp;&nbsp;&nbsp; 3D SSP (BELLHOP3D only;
      reads the SSP from a file)<br>
      'A' for Analytic.<span style=""></span><br>
      &nbsp;&nbsp;&nbsp; The user must modify the analytic formulas in
      ANALYT.FOR then re-compile and link. </p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText">If your not sure which option to take, I'd
      suggest<span style=""> </span>you use 'C'.<span style="">&nbsp;
        The 'N' option is virtually identical to 'C'. It's provided</span>
      <span style=""></span>to facilitate precise intermodel comparisons
      with codes that use a certain numerical technique that requires
      that type of interpolation.</p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Option 'S' is a little
      dangerous because splines<span style=""> </span>yield a poor fit
      to certain kinds of curves,<span style=""> </span>e.g. curves
      with sharp bends.<span style="">&nbsp; </span>If you insist<span
        style=""> </span>on splines, you can fix a bad fit by dividing
      the<span style=""> </span>water column into two 'media' at the
      bend.<br>
      <o:p></o:p><br>
      <span style=""></span>Run PLOTSSP to check that the SSP looks the
      way you<span style=""> </span>thought it should. Apart from
      potential typos,<span style=""> </span>this will also show up
      fit-problems.</p>
    <p style="font-family: monospace;" class="MsoPlainText"><o:p><br>
      </o:p></p>
    <div style="margin-left: 80px; font-family: monospace;">TOPOPT(2:2):
      Type of top boundary condition<br>
    </div>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText">'V' VACUUM above top<br>
      'A' ACOUSTO-ELASTIC half-space.<br>
      &nbsp;Requires another line with the halfspace parameters as
      described in block (4a).<br>
      'R' Perfectly RIGID<br>
      'F' <a href="ReflectionCoefficientFile.htm">Reflection
        coefficient from a FILE</a><br>
      <br>
      These files for complicated, multi-layered media can be generated
      using BOUNCE. (Available in KRAKENC, SCOOTER, and BELLHOP. Not
      available in KRAKEN and SPARC.) For a Top Reflection Coefficient,
      the file should have the extension '.TRC'. For KRAKEN/KRAKENC this
      option for tabulated reflection coefficients is <span style=""></span>somewhat
experimental
at







      this time. A complicated reflection coefficient may well cause <span
        style=""></span>problems for the mode-finder. Finally, a
      reflection coefficient <span style=""></span>tabulated only for
      real angles does not provide a good result <span style=""></span>for
complex
angles
of







      incidence. This happens when the sediment <span style=""></span>sound
speed
is
less







      than the water sound speed. In that case, the modes are evanescent
      in the upper part of the water column and therefore have a complex
      angle of incidence.</p>
    <div style="margin-left: 160px; font-family: monospace;"> </div>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>'S' for Soft-boss
      Twersky scatter.<br>
      'H' for Hard-boss Twersky scatter.<br>
      'T' for Soft-boss Twersky scatter, amplitude only.<br>
      'I' for Hard-boss Twersky scatter, amplitude<span style=""> </span>only.<br>
    </p>
    <div style="font-family: monospace;">
      <p style="margin-left: 120px;" class="MsoPlainText">The Twersky
        scatter options require<span style=""> </span>another line as
        described in block<span style=""></span>(4b). Mnemonically, T, I
        options are one letter after S, H in the alphabet. Current
        wisdom is that option T is most<span style=""> </span>appropriate






        for ice scatter.<br>
      </p>
    </div>
    <div style="margin-left: 120px; font-family: monospace;">
      <p class="MsoPlainText"><o:p></o:p><span style=""></span>For open
        ocean problems option 'V' should be used for the top BC.<span
          style="">&nbsp; </span>The Twersky options are intended for
        under-ice modeling.</p>
    </div>
    <div style="margin-left: 160px; font-family: monospace;"></div>
    <span style="font-family: monospace;"><br>
    </span>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>TOPOPT(3:3):
      Attenuation units.</p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>'N' Nepers/m.<br>
      <span style=""></span>'F' dB/(kmHz)<span style="">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;







      </span>(F as in Freq. dependent)<br>
      <span style=""></span>'M' dB/m<span style="">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;







      </span>(M as in per Meter)<br>
      'm' dB/m<span style="">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;







      </span>(m as in per Meter) Scaled with frequency; quadratically,
      then linearly above fT<br>
      <span style=""></span>'W' dB/wavelength<span style="">&nbsp;&nbsp;
      </span>(W as in per Wavelength)<br>
      <span style=""></span>'Q' quality factor<br>
      <span style=""></span>'L' Loss parameter (a.k.a. loss tangent)</p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><o:p></o:p><span style=""></span>KRAKEN
      ignores material attenuation<span style=""> </span>in elastic
      media. (KRAKENC treats<span style=""> </span>it properly).<br>
      The option 'm' for attenuation is a new one designed to capture a
      power-law frequency dependence. You provide an attenuation in dB/m
      at the frequency specified above (FREQ). Then in a broadband run,
      with multiple frequencies that attenuation as automatically scaled
      according to the power that you specify. If you use this without
      doing a broadband run, then 'M' and 'm' will do the same thing,
      i.e. interpret your attenuation as dB/m at the given frequency.<br>
    </p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>TOPOPT(4:4): Added
      volume attenuation.</p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>'T' Thorp attenuation
      formula.<br>
      'B' Biological layer (fish)<br>
    </p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText">If you invoke this option, Thorp attenuation
      is added to the explicitly specified attenuation (ap, as).<br>
    </p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><o:p>&nbsp;</o:p></p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>TOPOPT(5:5): Altimetry
      option; Slow/robust root-finder.</p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>'~' Read in a <a
        href="ATI_BTY_File.htm">*.ati file</a> containing the top
      altimetry. (BELLHOP only; '*' was used earlier and still works)<br>
      '_' Flat surface, i.e. no altimetry file. (BELLHOP only; this is
      the default if blank)<br>
      &nbsp;'.' As in: I want all the modes and I don't<span style=""> </span>care



      how long it takes. Period.<br>
    </p>
    <div style="margin-left: 120px; font-family: monospace;"> The '.'
      option works only with KRAKENC, which sometimes has trouble
      finding a complete set of modes in the complex plane.<br>
      <br>
      <br>
      <br>
    </div>
    <div style="margin-left: 80px; font-family: monospace;">TOPOPT(6:6):
      Single beam (BELLHOP only)
      <p style="margin-left: 120px; font-family: monospace;"
        class="MsoPlainText"><span style=""></span>'I' Calculate only a
        single beam from the specified fan.<br>
        &nbsp;&nbsp;&nbsp; The actual beam number is specified after
        NBEAMS, under<br>
        &nbsp;&nbsp;&nbsp; the section describing the beam fan.<br>
        ' ' Default: trace all beams<br>
      </p>
    </div>
    <div style="margin-left: 80px; font-family: monospace;">
      <div align="left">Broadband run (currently implemented in KRAKEN
        and SCOOTER)<br>
      </div>
      'B' Select a broadband run where multiple frequencies are
      specified<br>
    </div>
    <br>
    <div style="margin-left: 80px; font-family: monospace;">
      <div align="left">TOPOPT(7:7): Use 0 (zero) to disable stabilizing
        attenuation in SCOOTER </div>
    </div>
    <h4 style="font-family: monospace;"><a
        name="4a_-_Top_Halfspace_Properties_"></a>(4a) - Top Halfspace
      Properties<br>
    </h4>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Syntax:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span><var>ZT<span style="">&nbsp;







        </span>CPT<span style="">&nbsp; </span>CST<span style="">&nbsp;
        </span>RHOT<span style="">&nbsp; </span>APT<span style="">&nbsp;







        </span>AST</var></p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Description:</p>
    <div style="margin-left: 80px; font-family: monospace;">
      <p><span style=""></span>ZT:<span style="">&nbsp;&nbsp; </span>Depth







        (m).<br>
        CPT:<span style="">&nbsp; </span>Top P-wave speed (m/s).<br>
        CST:<span style="">&nbsp; </span>Top S-wave speed (m/s).<br>
        RHOT: Top density (g/cm3).<br>
        APT:<span style="">&nbsp; </span>Top P-wave attenuation. (units
        as given by Option(3:3) )<br>
        AST:<span style="">&nbsp; </span>Top S-wave attenuation. (<span
          style="">&nbsp; </span>"<span style="">&nbsp;&nbsp; </span>"<span
          style="">&nbsp;&nbsp;&nbsp; </span>"<span style="">&nbsp;&nbsp;&nbsp;







        </span>"<span style="">&nbsp;&nbsp; </span>"<span style="">&nbsp;&nbsp;






        </span>"&nbsp;&nbsp;&nbsp;&nbsp; )</p>
      <br>
    </div>
    <div style="margin-left: 40px; font-family: monospace;"><span
        style=""></span>This line should only be included if
      TOPOPT(2:2)='A', i.e. if the user has specified a homogeneous
      halfspace for the top BC.</div>
    <div style="margin-left: 40px; font-family: monospace;"><span
        style=""></span></div>
    <h4 style="font-family: monospace;"><a
        name="4c_-_Twersky_Scatter_Parameters_"></a>(4b) - Twersky
      Scatter Parameters<br>
    </h4>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Syntax:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span><var>BUMDEN<span
          style="">&nbsp; </span>ETA<span style="">&nbsp; </span>XI</var></p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Description:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>BUMDEN: Bump density
      (ridges/km).<br>
      ETA:<span style="">&nbsp;&nbsp;&nbsp; </span>Principal radius 1
      (m).<br>
      XI:<span style="">&nbsp;&nbsp;&nbsp;&nbsp; </span>Principal
      radius 2 (m).</p>
    <p style="font-family: monospace;" class="MsoPlainText"><span
        style="">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>This line should
      only be included when one of the<span style=""> </span>Twersky-scatter
options
is







      selected. </p>
    <h4 style="font-family: monospace;"><a
        name="4c_-_Twersky_Scatter_Parameters_"></a>(4c) - Biological
      Layer Parameters (for attenuation due to fish)<br>
    </h4>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Syntax:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span><var>NBioLayers<br>
        Z1<span style="">(1)&nbsp; </span>Z2(1)<span style="">&nbsp; </span>f0(1)


        &nbsp; Q(1) &nbsp; a0(1)</var><br>
      <var><var>Z1<span style="">(2)&nbsp; </span>Z2(2)<span style="">&nbsp;


          </span>f0(2) &nbsp; Q(2) &nbsp; a0(2)</var><br>
        .<br>
        .<br>
        .<br>
        Z1<span style="">(NBioLayers)&nbsp; </span>Z2(</var><var><var><span
            style="">NBioLayers</span></var>)<span style="">&nbsp; </span>f0(</var><var><var><span
            style="">NBioLayers</span></var>) &nbsp; Q(</var><var><var><span
            style="">NBioLayers</span></var>) &nbsp; a0(</var><var><var><span
            style="">NBioLayers</span></var>)</var><br>
      <var><var></var></var></p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Description:<br>
    </p>
    <span style=""></span><span style=""></span>
    <p style="font-family: monospace;" class="MsoPlainText"><span
        style="">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; z1:
        Top&nbsp;&nbsp;&nbsp; of layer (m)<br>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; z2: Bottom of layer
        (m)<br>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; f0: Resonance
        frequency (Hz)<br>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Q:&nbsp; Quality
        factor<br>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; a0: Amplitude<br>
      </span></p>
    <h3 style="font-family: monospace;"><a
        name="5a_-_Sound_Speed_Profile_"></a>(5) - Sound Speed Profile<br>
    </h3>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Syntax:<br>
    </p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span><var>NMESH<span
          style="">&nbsp; </span>SIGMA<span style="">&nbsp; </span>Z(NSSP)<br>
        Z(1)<span style="">&nbsp;&nbsp;&nbsp;&nbsp; </span>CP(1)<span
          style="">&nbsp;&nbsp;&nbsp;&nbsp; </span>CS(1)<span style="">&nbsp;&nbsp;&nbsp;&nbsp;






        </span>RHO(1)<span style="">&nbsp;&nbsp;&nbsp;&nbsp; </span>AP(1)<span
          style="">&nbsp;&nbsp;&nbsp;&nbsp; </span>AS(1)<br>
        <span style=""></span>Z(2)<span style="">&nbsp;&nbsp;&nbsp;&nbsp;







        </span>CP(2)<span style="">&nbsp;&nbsp;&nbsp;&nbsp; </span>CS(2)<span
          style="">&nbsp;&nbsp;&nbsp;&nbsp; </span>RHO(2)<span style="">&nbsp;&nbsp;&nbsp;&nbsp;






        </span>AP(2)<span style="">&nbsp;&nbsp;&nbsp;&nbsp; </span>AS(2)<br>
        <span style=""></span>.<br>
        <span style=""></span>.<br>
        <span style=""></span>.<br>
        <span style=""></span>Z(NSSP)<span style="">&nbsp; </span>CP(NSSP)<span
          style="">&nbsp; </span>CS(NSSP)<span style="">&nbsp; </span>RHO(NSSP)<span
          style="">&nbsp; </span>AP(NSSP)<span style="">&nbsp; </span>AS(NSSP)</var></p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Description:<br>
    </p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>NMESH:<span style="">&nbsp;&nbsp;







      </span>Number of mesh points used in the internal discretization.<br>
    </p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>The number of mesh
      points should be about 10<span style=""> </span>per vertical
      wavelength in acoustic media. In<span style=""> </span>elastic
      media, the number needed can vary quite<span style=""> </span>a
      bit; 20 per wavelength is a reasonable<span style=""> </span>starting







      point.</p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>The number of mesh<span
        style=""> </span><span style=""></span>points used depends on
      the initial mesh and the<span style=""> </span>number of times it
      is refined (doubled).<span style="">&nbsp; </span>The <span
        style=""></span>number of mesh doublings can vary from 1 to 5<span
        style=""> </span>depending on the parameter RMAX described<span
        style=""> </span><span style=""></span>below.</p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>If you type 0 for the
      number of mesh points,<span style=""> </span>the code will
      calculated NMESH automatically.<br>
    </p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText">BELLHOP ignores this parameter as it's not
      relevant to its numerical technique.<br>
    </p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>SIGMA:<span style="">&nbsp;&nbsp;







      </span>RMS roughness at the interface (ignored by BELLHOP and
      SPARC)<br>
    </p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><o:p></o:p>Z(NSSP): Depth at bottom of medium
      (m).<br>
      &nbsp;&nbsp; This value is used to detect the last SSP point<span
        style=""> </span>when reading in the profile that follows/<br>
    </p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Z():<span style="">&nbsp;&nbsp;&nbsp;&nbsp;







      </span>Depth (m).<br>
      &nbsp;&nbsp; The surface starts at the first depth point
      specified. Thus if you have say, XBT data which starts at 50 m
      below the surface, then you'll need to put in some SSP point at 0
      m, otherwise the free-surface would be placed at 50 m giving
      erroneous results. The points Z(1) and Z(NSSP) MUST correspond to
      the depths of interfaces between media.<br>
    </p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText">If the attenuation units were specified with
      option letter 'm' and a broadband run is selected, then the
      attenuation is scaled with frequency. The scaling is based on the
      frequency to a power beta, up to a transition frequency, fT. Above
      fT, the scaling is linear with frequency. The parameters that
      control this are specified in the first line of this block using
      the syntax:<br>
      <span style=""></span><var>NMESH<span style="">&nbsp; </span>SIGMA<span
          style="">&nbsp; </span>Z(NSSP) beta fT<br>
      </var></p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>CP():<span style="">&nbsp;&nbsp;&nbsp;







      </span>P-wave speed (m/s).<br>
      CS():<span style="">&nbsp;&nbsp;&nbsp; </span>S-wave speed (m/s).<br>
      RHO():<span style="">&nbsp;&nbsp; </span>Density (g/cm3).<br>
      &nbsp;&nbsp; Density variations within an acoustic medium<span
        style=""> </span>are at present ignored.<br>
    </p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText">AP():<span style="">&nbsp;&nbsp;&nbsp; </span>P-wave
attenuation
(units







      as given in Block 2)<br>
      AS():<span style="">&nbsp;&nbsp;&nbsp; </span>S-wave attenuation
      ( <span style="">&nbsp;</span>"<span style="">&nbsp;&nbsp; </span>"<span
        style="">&nbsp;&nbsp;&nbsp; </span>"<span style="">&nbsp;&nbsp;&nbsp;







      </span>"<span style="">&nbsp;&nbsp; </span>"<span style="">&nbsp;&nbsp;






      </span>")</p>
    <div style="margin-left: 80px; font-family: monospace;"><span
        style=""></span>These lines giving the SSP should be omitted
      when the 'A' option is used (indicating that an analytic profile
      is supplied by a user written subroutine).</div>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>The '/' character
      signals that the remaining data on the<span style=""> </span>line
      is the same as in the previous line of SSP data. For <span
        style=""></span>the very first line the default or 'previous'
      line is:</p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>0.0 1500.0 0.0 1.0 0.0
      0.0</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>This block should be
      repeated for each subsequent medium.<br>
    </p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText">Only KRAKEN, SCOOTER, and BOUNCE can use the
      shear wave information. SPARC and BELLHOP ignore it.<br>
    </p>
    <p style="font-family: monospace;" class="MsoPlainText"><o:p><br>
        &nbsp;</o:p></p>
    <h3 style="font-family: monospace;"><a name="6_-_Bottom_Option_"></a>(6)
-
Bottom







      Option<br>
    </h3>
    <p style="font-family: monospace;" class="MsoPlainText"><span
        style="">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>Syntax:</p>
    <p style="font-family: monospace;" class="MsoPlainText"><span
        style="">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span><var>BOTOPT<span
          style="">&nbsp; </span>SIGMA</var></p>
    <p style="font-family: monospace;" class="MsoPlainText"><span
        style="">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>Description:</p>
    <p style="font-family: monospace;" class="MsoPlainText"><span
        style="">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span>BOTOPT(1:1):







      Type of bottom boundary condition.</p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>'V' VACUUM below
      bottom.<br>
      <span style=""></span>'A' ACOUSTO-ELASTIC half-space.<br>
      &nbsp;&nbsp;&nbsp; Requires another line with the half-space
      parameters as described in Block (6a).<span style=""></span><br>
    </p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>'R' Perfectly RIGID.<br>
      'G' Grain size<br>
      'F' <a href="ReflectionCoefficientFile.htm">Reflection
        coefficient from a FILE</a><br>
      <br>
      These files for complicated, multi-layered media can be generated
      using BOUNCE. (Available in KRAKENC, SCOOTER, and BELLHOP. Not
      available in KRAKEN and SPARC.) For a Bottom Reflection
      Coefficient, the file should have the extension '.BRC'. For
      KRAKEN/KRAKENC this option for tabulated reflection coefficients
      is <span style=""></span>somewhat experimental at this time. A
      complicated reflection coefficient may well cause <span style=""></span>problems






      for the mode-finder. Finally, a reflection coefficient <span
        style=""></span>tabulated only for real angles does not provide
      a good result <span style=""></span>for complex angles of
      incidence. This happens when the sediment <span style=""></span>sound
speed
is
less







      than the water sound speed. In that case, the modes are evanescent
      in the upper part of the water column and therefore have a complex
      angle of incidence. </p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText"><br>
      'P' Precaculated internal reflection coefficient from a FILE
      (available in KRAKENC and SCOOTER, not KRAKEN).<br>
      &nbsp;&nbsp;&nbsp; These files are generated using BOUNCE.<br>
    </p>
    <p style="margin-left: 120px; font-family: monospace;"
      class="MsoPlainText">Option 'A' is generally used for ocean bottom
      modeling.<br>
    </p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText">BOTOPT(2:2):<br>
      &nbsp;&nbsp;&nbsp; '~' Read in a <a
        href="file:///Users/michaelporter/Desktop/at/doc/ATI_BTY_File.htm">*.bty






        file</a> containing the bottom bathymetry. (BELLHOP only; '*'
      was used earlier and still works)<br>
      &nbsp;&nbsp;&nbsp; '_' Flat surface, i.e. no bathymetry file.
      (BELLHOP only; this is the default if blank)<br>
    </p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>SIGMA:<span style="">&nbsp;







      </span>Interfacial roughness (m).</p>
    <p style="font-family: monospace;" class="MsoPlainText"><o:p>&nbsp;</o:p></p>
    <h4 style="font-family: monospace;"><a
        name="6a_-_Bottom_Halfspace_Properties_"></a>(6a) - Bottom
      Halfspace Properties from geoacoustic values<br>
    </h4>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Syntax:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span><var>ZB<span style="">&nbsp;







        </span>CPB<span style="">&nbsp; </span>CSB<span style="">&nbsp;
        </span>RHOB<span style="">&nbsp; </span>APB<span style="">&nbsp;







        </span>ASB</var></p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Description:</p>
    <div style="margin-left: 80px; font-family: monospace;">
      <p><span style=""></span>ZB:<span style="">&nbsp;&nbsp; </span>Depth







        (m).<br>
        CPB:<span style="">&nbsp; </span>Bottom P-wave speed (m/s).<br>
        CSB:<span style="">&nbsp; </span>Bottom S-wave speed (m/s).<br>
        RHOB: Bottom density (g/cm3).<br>
        APB:<span style="">&nbsp; </span>Bottom P-wave attenuation.
        (units as given by TOPOPT(3:3) )<br>
        ASB:<span style="">&nbsp; </span>Bottom S-wave attenuation. (<span
          style="">&nbsp; </span>"<span style="">&nbsp;&nbsp; </span>"<span
          style="">&nbsp;&nbsp;&nbsp; </span>"<span style="">&nbsp;&nbsp;&nbsp;







        </span>"<span style="">&nbsp;&nbsp; </span>"<span style="">&nbsp;&nbsp;






        </span>"&nbsp;&nbsp;&nbsp;&nbsp; )</p>
      <br>
    </div>
    <div style="margin-left: 40px; font-family: monospace;"><span
        style=""></span>This line should only be included if
      BOTOPT(1:1)='A', i.e. if the user has specified a homogeneous
      halfspace for the bottom BC.<o:p><br>
        &nbsp;</o:p><br>
    </div>
    <div style="margin-left: 40px; font-family: monospace;"><span
        style=""></span>These lines should be contained in a separate
      '.BRC' file. This file is only required if BOTOPT(2:2)='F', i.e.
      if the user has specified that the bottom BC is read from a '.BRC'
      (Bottom Reflection Coefficient) file. </div>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>For KRAKEN/KRAKENC this
      option for tabulated reflection coefficients is <span style=""></span>somewhat
experimental
at







      this time. A complicated reflection coefficient may well cause <span
        style=""></span>problems for the mode-finder. Finally, a
      reflection coefficient <span style=""></span>tabulated only for
      real angles does not provide a good result <span style=""></span>for
complex
angles
of







      incidence. This happens when the sediment <span style=""></span>sound
speed
is
less







      than the water sound speed. In that case, the modes are evanescent
      in the upper part of the water column and therefore have a complex
      angle of incidence.<br>
    </p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><br>
    </p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"> </p>
    <h4 style="font-family: monospace;"><a
        name="6a_-_Bottom_Halfspace_Properties_"></a>(6b) - Bottom
      Halfspace Properties from grain size<br>
    </h4>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Syntax:</p>
    <p style="margin-left: 80px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span><var>ZB<span style="">&nbsp;
        </span>MZ<span style=""></span><span style=""></span><span
          style=""></span><span style=""><br>
        </span></var></p>
    <p style="margin-left: 40px; font-family: monospace;"
      class="MsoPlainText"><span style=""></span>Description:</p>
    <div style="margin-left: 80px; font-family: monospace;">
      <p><span style=""></span>ZB:<span style="">&nbsp; </span>Depth
        (m).<br>
        MZ:<span style="">&nbsp; </span>Grain size (phi units).<br>
        <br>
      </p>
      <br>
    </div>
    <div style="margin-left: 40px; font-family: monospace;"><span
        style=""></span>This line should only be included if
      BOTOPT(1:1)='G', i.e. if the user has specified a homogeneous
      halfspace for the bottom BC defined by grain size. The bottom
      sound speed, attenuation, and density is calculated using formulas
      from the UW_APL High-Frequency handbook.<o:p><br>
        &nbsp;</o:p><br>
    </div>
    <div style="margin-left: 40px; font-family: monospace;"><span
        style=""></span><br>
    </div>
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