How to adjust temperature mix, salinity advection and overall vertical mixing in roms

[azamocndu]

Hi

Model output shows SST is about 3 to 4 degrees high only during March and April (highest heating season); other months are not bad . subsurface/thermocline temperature is lower than World Ocean Atlas data. Surface salinity is also not bad but very low near river estuary. My domain is the Bay of Bengal, part of Indian ocean.

I'm using MY2.5 scheme for mixing. Used COADS climatology atmospheric forcing (#define QCORRECTION; #define TCORRECTION)
I have used ( TNU2 == 5.0d0 5.0d0 & AKT_BAK == 1.0d-6 1.0d-6 ! m2/s; AKV_BAK == 1.0d-4 ; AKK_BAK == 5.0d-5 ; AKP_BAK == 5.0d-5 ) before

I guess (to solve those problems):
1) I need to increase temperature mixing (AKT_BAK == 1.0d-4 (temperature) 1.0d-6 (salinity) )??
2) need to increase salinity advection ( TNU2 == 5.0d0 (temperature) 30.0d0 (salinity) ) ??
3) need to increase overall mixing (AKV_BAK == 1.0d-3 ; AKK_BAK == 5.0d-4 ; AKP_BAK == 5.0d-4) ??

Am I doing right? or I actually new in ROMS. Please give me some easy way to solve it.

I will be very glad hearing from any kind person.

Thanks

Azam
Email: azam_oceanographer.ocn@du.ac.bd

[c.drinkorn]

Hi Azam,

just an idea: Did you try switching between Laplacian and biharmonic horizontal diffusion? I.e., define either TS_DIF2 or TS_DIF4. I don't know whether the issue is too less horizontal or vertical mixing but I guess if your subsurface temperature AND salinity is too low you need more vertical convection? I am not familiar with the Bay of Bengal but if you have a lot of precipitation and river runoff you need more efficient convection in order to obtain a warmer and more saline subsurface. Maybe also try another vertical tracer advection scheme...

[kate]

I've heard it's a difficult problem. We also have too little vertical mixing from all the fresh water input into the Gulf of Alaska. One idea is that we need to couple to a wave model and enable the wind-wave surface mixing in COAWST. Easier said than done; we haven't tried it yet.

[azamocndu]

Hi, c.drinkorn

Thanks for your reply. I didn't try it before. yes Surface T is higher but in 50 to 300 meters depth it is 2-3 degrees low. salinity is less problematic than temperature. Surface salinity is very fresh near river mouth.
Thanks again



Hi Kate

Thanks for your comments