Last edited Timestamp?

Direct Model Changes

---

Some modifications and additions are compulsory to integrate the Tangent and Adjoint Module to NEMO. They mainly consist in:

• changing subroutines or parameters declaration from Private to Public for:
  • initialization
  • re-use
• adding a subroutine to save the trajectory
• adding parameters
• updating namelist

1 - Non-Linear Trajectory

To evaluate the tangent and/or the adjoint at a time t, some actual parameters of the direct model are needed at the corresponding time t. To fulfill this purpose a subroutine, asm_trj_wri is added to write the trajectory. It is controlled with two logical parameters: lk_asminc and ln_trjwri. The trajectory is saved with a certain saving frequency and only both logical parameter are set to TRUE. Th

Subroutine: asm_trj_wri

A new subdirectory is created into /OPA/ named ASM. The file is asmtrj.F90. The purpose of this routine is to write to file the model state trajectory for use with 4DVar. It is called in opa_model routine to save the initial state needed for the TAM and at the end of the stp routine.

Currently the following parameters are saved:

Parameters	Associated ccp keys
emp
emps
un
vn
tn
sn
ta
sa
tb
sb
avmu
avmv
aeiu	lk_traldf_eiv
aeiv	lk_traldf_eiv
aeiw	lk_traldf_eiv
uslp	key_ldfslp
vslp	key_ldfslp
wslpi	key_ldfslp
wslpj	key_ldfslp
avs	key_zdfddm
strdmp	key_tradmp
hmlp	key_tradmp

note: is it worth to add why (and where) there will be a need of these variables later in TAM?

Specific management of the initial state

For the initial state of the model, some parameters need to be computed in asmtrj as they are not yet computed in opa.

note: we still have zero value in emp/emps parameters. It needs to be solved quickly.

Linear Interpollation

For efficiency matters, the whole trajectory is of course not saved. Only a predefined steptime frequency is saved. The frequency nittrjfreq is controlled by namelist. The intermediate steptime will be estimated in TAM by linear interpollation.

Namelist

Parameters related to the model state saving is controlled by the namelist nam_asminc with:

• ln_trjwri: Logical switch for writing out state trajectory
• nittrjfrq: frequency of the trajectory used in 4D-VAR

2 - Routine modification

• opa.F90:
  • include output trajectory fields (USE asmtrj and CALL asm_trj_wri)
• step.F90:
  • include output trajectory fields (CALL asm_trj_wri)
  • add temporary variables to save ta/sa (used as workspace in standard)

3 - Declaration Changes

The following table describes the change from PRIVATE to PUBLIC of some routines and parameters.

Modules	Routines	parameters
dynadv	dyn_adv_ctl
daymod	day_mth
		sec1jan000
eosbn2		neos_init
sbcmod		all from namelist namsbc
tradmp	cofdis, dtacof, dtacof_zoom
		strdmp, ttrdmp, resto
traqsr		nksr, gdsr

note: is it worth to add why (and where) there will be a need of these variables later in TAM?