Re: Negative rivers

[Alan Wallcraft]

Luana,

Negative rivers should work.  Note that positive rivers add freshwater to the water column, which reduces its salinity but this can never get below zero.  On the other hand, negative rivers remove freshwater from the water column which increases the salinity of the remaining water and this is unbounded, i.e. for strong forcing the salinity could get a 1000 psu (say).

I suggest setting itest,jtest to a negative river point, because the arch*.txt file includes  E-P (from atmosphere),  sssE-P (from SSS relaxation) and rivE-P (from rivers).  So you can monitor its progress.  I suggest using epmass=0 (virtual salt flux) or epmass=2 (water flux only at rivers), because epmass=1 (water flux everywhere) might swamp your negative river with a basin-wide correction (sssbal=1) or cause a large drift in SSH.

Alan

On Wed, Aug 13, 2025 at 7:50 AM Luana F. Bueno <lufer...@hotmail.com> wrote:

Hi Alan,

I'm currently using river inputs with negative transport values to simulate an increase in salinity in a specific region. The forcing.rivers.[ab] files appear to be correctly configured, and the model runs successfully with them.

However, after two months of integration, I haven’t observed any noticeable difference compared to the control run. I'm wondering whether this is simply due to the short simulation period, or if the negative river inputs might not be properly accounted for by the model.

What are your thoughts on it? 
I thought about maybe forcing the rivers more frequent than monthly. I also tried to run away of touching the evaporation itself. 

Best wishes, 
Luana 

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