WhatIs: The tracer.def input file

The tracer.def input file

This file contains information on the tracers that will be advected in the dynamics. It should be used instead of the now depreciated traceur.def input file.

Simple example of a tracer.def file

&version=1.0
&lmdz
default    type=tracer  phases=g    hadv=10   vadv=10   parent=air
H2O                                 hadv=14   vadv=14
H2O                     phases=ls
Aga

• The mandatory first line &version is there to handle (potential) versioning of these file and their format
• The mandatory second line &lmdz is there to specify the scope of the following lines, i.e. that all that follow is relevant for the LMDZ lon-lat dynamical core.
• The mandatory third line starting with default specifies the default attributes for all the tracers. In this example that they are of type tracer (as opposed to type tag for tagging), that there phase is g (gas), that they are advected using advection schemes hadv and vadv 10 (Van Leer advection scheme) and that their parent (i.e. carrier fluid) is air.
• Then one should specify on successive lines the tracer names and optionally their properties such as phases (g: gas, l: liquid, s:solid). Note that one may condense information about phases using a mix of letters g/l/s rather than specifying the information for each on a separate line. In practice the lines

H2O                                 hadv=14   vadv=14
H2O                     phases=ls

From the example above which specifies there are 3 H2O phases (gas, liquid and solid), where the gas phase is advected with the hadv and vadv 14 dedicated scheme could also be written more explicitly as:

H2O                     phases=g    hadv=14   vadv=14
H2O                     phases=l
H2O                     phases=s

A more advanced example of a tracer.def file

The following example includes water isotopes (identified by the fact that their parent is not air but the tracer H2O) with two tags (con and oce)

&version=1.0
&lmdz
default hadv=10 vadv=10 phases=g parent=air type=tracer
H2O hadv=14 vadv=14
H2O phases=ls
RN,PB
H2[18]O,H[2]HO,H2[16]O phases=gls parent=H2O
con,oce phases=gls parent=H2[18]O,H[2]HO,H2[16]O type=tag

03/01/2023