On-line Floats trajectories (FLO) (key_ floats)

!-----------------------------------------------------------------------
&namflo       !   float parameters                                      ("key_float")
!-----------------------------------------------------------------------
   jpnfl         = 1          !  total number of floats during the run
   jpnnewflo     = 0          !  number of floats for the restart
   ln_rstflo     = .false.    !  float restart (T) or not (F)
   nn_writefl    =      75    !  frequency of writing in float output file
   nn_stockfl    =    5475    !  frequency of creation of the float restart file
   ln_argo       = .false.    !  Argo type floats (stay at the surface each 10 days)
   ln_flork4     = .false.    !  trajectories computed with a 4th order Runge-Kutta (T)
                              !  or computed with Blanke' scheme (F)
   ln_ariane     = .true.     !  Input with Ariane tool convention(T)
   ln_flo_ascii  = .true.     !  Output with Ariane tool netcdf convention(F) or ascii file (T)
/

The on-line computation of floats advected either by the three dimensional velocity field or constraint to remain at a given depth ($w = 0$ in the computation) have been introduced in the system during the CLIPPER project. Options are defined by namflo namelis variables. The algorithm used is based either on the work of Blanke and Raynaud [1997] (default option), or on a $4^th$ Runge-Hutta algorithm (ln_flork4=true). Note that the Blanke and Raynaud [1997] algorithm have the advantage of providing trajectories which are consistent with the numeric of the code, so that the trajectories never intercept the bathymetry.

Input data: initial coordinates

Initial coordinates can be given with Ariane Tools convention ( IJK coordinates ,(ln_ariane=true) ) or with longitude and latitude.

In case of Ariane convention, input filename is init_float_ariane. Its format is:

I J K nisobfl itrash itrash

with:

- I,J,K : indexes of initial position

- nisobfl: 0 for an isobar float, 1 for a float following the w velocity

- itrash : set to zero; it is a dummy variable to respect Ariane Tools convention

- itrash :set to zero; it is a dummy variable to respect Ariane Tools convention

Example:
100.00000 90.00000 -1.50000 1.00000 0.00000
102.00000 90.00000 -1.50000 1.00000 0.00000
104.00000 90.00000 -1.50000 1.00000 0.00000
106.00000 90.00000 -1.50000 1.00000 0.00000
108.00000 90.00000 -1.50000 1.00000 0.00000

In the other case ( longitude and latitude ), input filename is init_float. Its format is:

Long Lat depth nisobfl ngrpfl itrash

with:

- Long, Lat, depth : Longitude, latitude, depth

- nisobfl: 0 for an isobar float, 1 for a float following the w velocity

- ngrpfl : number to identify searcher group

- itrash :set to 1; it is a dummy variable.

Example:

20.0 0.0 0.0 0 1 1
-21.0 0.0 0.0 0 1 1
-22.0 0.0 0.0 0 1 1
-23.0 0.0 0.0 0 1 1
-24.0 0.0 0.0 0 1 1

jpnfl is the total number of floats during the run. When initial positions are read in a restart file ( ln_rstflo= .TRUE. ), jpnflnewflo can be added in the initialization file.

Output data

nn_writefl is the frequency of writing in float output file and nn_stockfl is the frequency of creation of the float restart file.

Output data can be written in ascii files (ln_flo_ascii = .TRUE. ). In that case, output filename is trajec_float.

Another possiblity of writing format is Netcdf (ln_flo_ascii = .FALSE. ). There are 2 possibilities:

- if (key_ iomput) is used, outputs are selected in iodef.xml. Here it is an example of specification to put in files description section:

  

     <group id="1d\_grid\_T" name="auto" description="ocean T grid variables" >   }

       <file id="floats"  description="floats variables"> }\\

           <field ref="traj\_lon"   name="floats\_longitude"   freq\_op="86400" />}

           <field ref="traj\_lat"   name="floats\_latitude"    freq\_op="86400" />}

           <field ref="traj\_dep"   name="floats\_depth"       freq\_op="86400" />}

           <field ref="traj\_temp"  name="floats\_temperature" freq\_op="86400" />}

           <field ref="traj\_salt"  name="floats\_salinity"    freq\_op="86400" />}

           <field ref="traj\_dens"  name="floats\_density"     freq\_op="86400" />}

           <field ref="traj\_group" name="floats\_group"       freq\_op="86400" />}

       </file>}

  </group>}

- if (key_ iomput) is not used, a file called trajec_float.nc will be created by IOIPSL library.

See also here the web site describing the off-line use of this marvellous diagnostic tool.