It is running fine till the adjoint run in the last inner loop. After the corresponding Descent Algorithm (in inner loop# 30) the values of free-surface, u and v-momentum component, potential temperature and salinity in the input tangent linear model initial conditions file (namely, *_itl.nc) increase abruptly as seen in the following log:

Code: Select all

```
TLM: GET_STATE - Read state initial conditions, t = 9710 00:00:00
(Grid 01, File: io_1x12_itl.nc, Rec=0001, Index=1)
- free-surface
(Min = -1.05473263E+03 Max = 8.77788746E+02)
- free-surface, open boundaries
(Min = -6.16861539E-01 Max = 2.13182573E-01)
- vertically integrated u-momentum component
(Min = 0.00000000E+00 Max = 0.00000000E+00)
- vertically integrated u-momentum component, open boundaries
(Min = 0.00000000E+00 Max = 0.00000000E+00)
- vertically integrated v-momentum component
(Min = 0.00000000E+00 Max = 0.00000000E+00)
- vertically integrated v-momentum component, open boundaries
(Min = 0.00000000E+00 Max = 0.00000000E+00)
- surface u-momentum stress, adjusted tl_ustr
(Min = -4.47085764E-01 Max = 8.82287023E-01)
- surface v-momentum stress, adjusted tl_vstr
(Min = -2.79389044E-01 Max = 3.06903690E-01)
- u-momentum component
(Min = -2.21421791E+06 Max = 1.21455456E+06)
- u-momentum component, open boundaries
(Min = -1.00039186E-01 Max = 3.04749362E-02)
- v-momentum component
(Min = -1.45533555E+06 Max = 1.45103002E+06)
- v-momentum component, open boundaries
(Min = -1.13609944E-01 Max = 4.29629471E-02)
- potential temperature
(Min = -4.40319194E+03 Max = 7.84010994E+04)
- salinity
(Min = -3.24198687E+04 Max = 4.41747228E+04)
- potential temperature, open boundaries
(Min = -6.09766327E-02 Max = 1.63820702E-01)
- salinity, open boundaries
(Min = -2.45726672E-02 Max = 4.26380653E-03)
- surface net heat flux, adjusted tl_tflux
(Min = -7.60638358E-07 Max = 1.92845377E-02)
- surface net salt flux, (E-P)*SALT, adjusted tl_tflux
(Min = -8.47218473E-07 Max = 9.61237175E-03)
WRT_INI - wrote initial fields (Iter=0032, Index=1,1, Rec=0001)
```

I have tried to locate the problem with increasing the friction, changing the decorrelation scales, increasing the # of the inner loop, enabling/disabling ADJUST_BOUNDARY, ADJUST_WSTRESS, ADJUST_STFLUX, and also with relaxing T and S. But the problem still persists.

I have attached the figures of tangent linear u and v-momentum component at the surface. I don't have any clue what causes this sudden increment of these values. Any kind of help or advice would be highly appreciated. Thanks in advance.