WhatIs: The traceur.def input file

The traceur.def input file tells LMDZ about the tracers to advect

The traceur.def is a plain text file that is read at run time by LMDZ. Its format is quite strict:

• The first line contains the number n of tracers to advect in the dynamics
• The n following lines contain the following set ( two integer numbers and a string): hadv , vadv, tname . hadv and vadv are traceur advection scheme numbers and tname is the tracer name

Tracer advection schemes

A few are coded, but not for the parallel case, so we only present the important (i.e. operational) ones here:

• 0 : no advection. This tracer will not be advected by the dynamics
• 10: advection using a Van Leer scheme. This is the standard advection scheme to use for tracers.
• 14: a specific advection scheme for the water vapor tracer (i.e. "H2Ov")

Illustrative example

In practice a "traceur.def" file will look like this:

4
14 14 H2Ov
10 10 H2Ol
10 10 H2Oi
00 00 Aga

In this example, there are 4 tracers, the first one is "H2Ov" (water vapor) and advected using scheme number 14, the second and third are "H2Ol" (liquid water) and "H2Oi" (water ice), and the last is called "Aga" and completely passive (i.e. untouched by the dynamics).

The tracer.def input file

Note that the use of a traceur.def file as described above is now depreciated (but should still work fine as the code is retro-compatible) and that it is recommended to now use a tracer.def as described here.

03/01/2023