# Improving Model–Observation Agreement: Adding Residual (Surge) to TPXO

**URL:** <https://opentelemac.org/forum/t/improving-model-observation-agreement-adding-residual-surge-to-tpxo/8053>\
**Category:** TELEMAC-2D\
**Created:** [September 17, 2025, 11:35am UTC](https://opentelemac.org/forum/t/improving-model-observation-agreement-adding-residual-surge-to-tpxo/8053 "2025-09-17T11:35:30Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![user\_11755](https://opentelemac.org/forum/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@user\_11755](https://opentelemac.org/forum/u/user_11755)\
**Post date:** [September 17, 2025, 11:35am UTC](https://opentelemac.org/forum/t/improving-model-observation-agreement-adding-residual-surge-to-tpxo/8053/1 "2025-09-17T11:35:30Z")

</div>

Dear [name removed],

I am currently running a test case for a coastal–estuarine region. I started with TELEMAC-2D and the results are quite good so far. The model is forced with TPXO09 tides at the open boundaries, as well as time-varying discharge and wind forcing.

 ![Figure_1.png](https://opentelemac.org/uploads/default/original/2X/4/411e6906e997ff421aa141298b86939b0be55f63.png)

As you can see, the observed signal still shows a residual component—most likely meteorological tides—that is not captured by the model.

My questions are:

Is there any way to improve the overall validation? I have tried adjusting various coefficients, but nothing seems to match the observations.

I am considering adding a residual signal extracted from offshore observational data to the TPXO-derived boundary values, so that the model would also account for meteorological tides. Is this approach recommended, and if so, how should it be implemented?

Best regards,

---

<div class="post-metadata">

**Author:** ![user\_63](https://opentelemac.org/forum/letter_avatar_proxy/v4/letter/u/c4cdca/32.png) [@user\_63](https://opentelemac.org/forum/u/user_63)\
**Post date:** [September 18, 2025, 7:05am UTC](https://opentelemac.org/forum/t/improving-model-observation-agreement-adding-residual-surge-to-tpxo/8053/2 "2025-09-18T07:05:15Z")

</div>

Hi

In addition to the wind forcing, I would recommend to also take in account the pressure effect.

There is an option to take in account the barometric effect at the tidal boundaries…

Regards

---

<div class="post-metadata">

**Author:** ![user\_11755](https://opentelemac.org/forum/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@user\_11755](https://opentelemac.org/forum/u/user_11755)\
**Post date:** [September 18, 2025, 3:16pm UTC](https://opentelemac.org/forum/t/improving-model-observation-agreement-adding-residual-surge-to-tpxo/8053/3 "2025-09-18T15:16:05Z")

</div>

Thank you [name removed].

I am gonna do that. I saw your merge request on the gitlab. Is it just a matter of keyword? ATMOSPHERIC PRESSURE ON TIDAL BOUNDARIES = YES?

Do you do that based on an ASCII ATMOSPHERIC FILE with the pressure values or BINARY ATMOSPHERIC FILE? Is it a V8P5 update? i am using now V8P4 version?

Best regards,

---

<div class="post-metadata">

**Author:** ![user\_63](https://opentelemac.org/forum/letter_avatar_proxy/v4/letter/u/c4cdca/32.png) [@user\_63](https://opentelemac.org/forum/u/user_63)\
**Post date:** [September 18, 2025, 3:38pm UTC](https://opentelemac.org/forum/t/improving-model-observation-agreement-adding-residual-surge-to-tpxo/8053/4 "2025-09-18T15:38:27Z")

</div>

Hi [name removed]

I developed this on my own version in v8p4 but this has been officially implemented in v8p5 so I think you should update your version.

In my case I work with Binary atmospheric file but i think this could work also with ascii atmospheric file…

Regards