.nd file format: Introduction

The .nd file format is based on the named discontinuity format used by the TauP Toolkit (Crotwell et al., 1999). It is a human readable ASCII format which defines velocity, density and Q factor at discrete depths.

For TTBOX, the format has been extended a little: it is now possible to store the planetary radius, the model name, and the year in which the model was published.

The Routines MKREADND and MKWRITEND read and write .nd-files from disk.

The Format consists of the following elementary building blocks:

  1. data lines to specify velocity, density and Q factor at depth
  2. discontinuity name lines to specify the depth of prominent 1st order discontinuities
  3. Unnamed Discontinuities
  4. comments to give arbitrary additional information (which is not evaluated during file reading)
  5. keyword lines to specify planet radius, model name, and year of model publication

Here comes a simple example of a .nd file, which demonstrates all features:

  
/* Simple sample Model */
!name simplesample
!year 2002
!radius 6375 // The Radius!
0.0  5.0  3.0  2.7 // Qp and Qs undefined
20   5.0  3.0  2.7 100 // Qs undefined
20   6.5  3.7  2.9	200	300 // Qp and Qs defined
33   6.5  3.7  2.9 -1 -1 // Q factors undefined!
mantle # this is the Moho
33   7.8  4.4  3.3
410  8.9  4.7  3.5 # here is an unnamed discontinuity!
410  9.1  4.9  3.7 // some parms in here # and complicated comment
670  10.2 5.5  4.0
670  10.7 5.9  4.4 # some complicated comment // after the parms
2891 13.7 7.2  5.6
outer-core // here begins the outer core
2891 8.0  0.0  9.9
5149.5 10.3 0.0 12.2
inner-core
5149.5 11 3.5 12.7
6371 11.3  -1  13 // vs undefined!
  

As you see, there are different (but equivalent) ways to define a comment. Comments may start right in the middle of a line. Undefined Parameters may simply be omitted, or declared to be -1, what is a physically meaningless value for all quantities.

The following sections describe the building blocks of .nd-files in detail:


eof.