Temperature and Salinity anomaly in GULF STREAM

[Keke]

Hello everyone,

I found big Temperature and Salinity anomaly in GULF STREAM in DOME ATLb200 (contour lines show the time-mean difference compared with WOA13) and GLBa0.08 (on page 13 about SSS anomaly). My queston is how to solve this problem. I try to modify blkdat.input following GLBa0.08 but in monthly ERA-15 forcing, big Temperature and Salinity anomaly in GULF STREAM still. I finally guess the resolution may be the key.

I would really appreciate any suggestions about the simulation around GULF STREAM.

Thank you very much.

[alan.wa...@hycom.org]

We distribute the ATLb2.00 test case because it is cheap to run, not because it gives good results.

You might want to look at the Atlantic in our new GLBt0.72 test case.

https://github.com/HYCOM/HYCOM-examples

It deliberately increases the viscosity and the diffusivity to shut down mid-latitude eddies, and may be about as good as you can do without resolving the Gulf Stream.

It should not be hard to setup a similar Atlantic-only region.  You can either subregion the GLBt0.72 domain (but it is curvilinear north of 40N), or define your own rectilinear region using  either grid_mercator or grid_latitude (use the latter to get 0.36 degree resolution at the equator, like GLBt0.72).

The Gulf Stream is a hard western boundary current to get right.  Even our 1/12 degree global model without data assimilation has some issues in this region.

See:

P. G. Thoppil, J. G. Richman and P. J. Hogan, 2011:
Energetics of a global ocean circulation model compared to observations
Geophysical Reseearch Letters vol 38 L15607 doi:10.1029/2011GL048347

and

H. E. Hurlburt, E. J. Metzger, J. G. Richman, E. P. Chassignet, Y. Drillet, M. W. Hecht, O. Le Galloudec, J. F. Shriver, X. Xu and L. Zamudio, 2011:
Dynamical Evaluation of Ocean Models Using the Gulf Stream as an Example
Operational Oceanography in the 21st Century Chapter 21

Alan.