COHERENS forum

Hi,
Although I know that this post will take long time to be replied by sb. but there is a serious problem in the test case rhone. it doesn't run for more than 2.5 months (or less). it's 3months that I'm dealing with this problem but it seems that only the developers can remove it.
Please consider it as it's just wasting of my time working on coherens...(unfortunately I can't switch to another model at the moment)._
Thank you,
Sue

Dear Sue,

Firstly, I must apologise for the late reply. I have run the test case Rhone for three months. It crashed after about two weeks. Looking at the setup I found that the switch iopt_dens_grad which sets the scheme for the baroclinic pressure gradient was set to 2 (z-level scheme). I found in other applications that this scheme is not fully reliable, so I changed its value to 3 (Shchepetkin & Mc Williams algorithm). This previous crash no longer occurred but the run still crashed now after abound two months due to instabilities generated at the (southern) open boundary. This could be improved by extending the boundary or changing the type of open boundary condition or imposing a realistic surface (wind) forcing. Note that the setup of the Rhone test case is very idealistic. Currents are very small in the absence of additional forcing and therefore prone to instabilites in the absence of external forcings.

Let me know if you like further information. If needed, I could make some additional tests.

Patrick

Hello Patrick,
Thank you. But I spent 4months on this problem and fixed the problem by changing these switches and obc, about 3 weeks ago.
Thank you very much and I appreciate you and other developer's effort but I really hope to have more active forum for saving the time....
Sue