River Input

[Fatima]

Dear John,
I want to define a river in my idealized axisymmetric lake rather than as a point. I want to have distributed river input across the whole lake surface. Is it possible, or must I define it as source/sink points?

Best regards,
Fatima

[kate]

You have two choices: add a second field much like precipitation, or add a bunch of individual sources.

[wilkin]

I'm struggling to envision what geophysical problem it is you are trying to model, but if you want to add mass (volume) at some rate (cubic meters per second) distributed all across the surface of your lake, then you have to create all the point sources. It sounds like this is an idealized problem, so with a bit of careful thought it can probably be done through Functional ana_psource.h with nested loops over i and j, and automatic accounting of the appropriate Nsrc.

Using the existing precipitation forcing variable will convert the freshwater volume flux (precipitation is expressed as a velocity) to an equivalent salt flux, and will not add mass (volume). So that is probably not what you want. In fact, if surface salinity is exactly zero then I think precipitation does nothing at all. Check in Nonlinear/set_vbc.F to see.

[Fatima]

Dear John and Kate,
Thank you for your reply.
I added two rivers (using create_roms_rivers.m in COAWST m files) to my idealized ice-covered lake with a homogenous salinity of 14 psu. The surface temperature was set to freezing point temperature, with an initial linear stratification within the water column to a temperature of maximum density at the bottom. There were 45 km (500*500) of length and 150 m of depth (30 vertical layers) in my lake.
The river direction in both rivers is 0 (x-direction), and river transport is 1. The river temperature was set to freezing point temperature, and the salinity was equal to 0 psu.
I ran the model (LuvSrc was true). I found that one of the rivers had an inflow and the other had an outflow. It is difficult for me to understand how these rivers flow in different directions.

[kate]

Rivers can be tricky! Each uv-source is either a u-source or a v-source. Each u-source is either going to the east or to the west. You want one of each, so one is positive, one is negative. When following a realistic coastline, I have some Python code to figure this all out for each source (used to be Perl).

[Fatima]

Dear kate,
Thanks for getting back to me.
Are these phyton files on your GitHub?
I want to add some fresh water to my idealized lake. Adding several rivers is the best option. Can I add Qs? I cannot add a file like precipitation because it is an ice-covered lake.

[wilkin]

This is explained in WikiROMS:

For uv source you must be mindful of the placement of land and water to the "left" or "right" of the cell interface:
https://www.myroms.org/wiki/River_Runof ... _Eposition

You need to change the sign of the river entering the ocean in the negative coordinate direction:
https://www.myroms.org/wiki/River_Runof ... _transport

[kate]

My latest in Python rivers are at https://github.com/ESMG/pyroms/tree/pyt ... ill_runoff

[Fatima]

Hi all,
Thank you, John and Kate.
I run a model with two river inflows. I added solar radiation effects to this model (#define SOLAR_SOURCE).
I cannot run it because the model needs a forcing file (It works without river inflow).

I defined

#define ANA_SMFLUX
#define ANA_STFLUX
#define ANA_SSFLUX
#define ANA_BSFLUX
#define ANA_SPFLUX

How can I run my idealized model without a forcing file?

[wilkin]

You might need ...

** ANA_SRFLUX if analytical surface shortwave radiation flux **

[Fatima]

Thank you for your thoughtful response.
I added solar radiation effects to the model, but I couldn't keep the surface temperature at 0 degrees throughout the entire model run. Is there any way to achieve this?

[wilkin]

You say you want to keep the ocean surface temperature at 0 degrees ... so it freezes?

Please post a more detailed question and do so in a new thread because this no longer has anything to do with River Inputs.

[Fatima]

Dear John,
I want to run an idealized ice-covered lake with a homogenous salinity of 0 PSU (I did not add an ice model). The surface temperature was set to freezing point temperature, with an initial linear stratification within the water column to a temperature of maximum density at the bottom. My lake had 45 km (500*500) length and 150 m depth (30 vertical layers).
I want to model T_CML and H_CML (convectively mixed layer (CML)).
I added solar radiation effects to the model but couldn't keep the surface temperature at 0 degrees C throughout the entire model run. Is there any way to achieve this or at least reduce the speed of surface warming?

[wilkin]

Adding solar radiation will heat the ocean. An ice covered lake is insulated from solar heating.