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PostPosted: Wed Oct 07, 2015 1:14 pm 
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Joined: Tue Oct 08, 2013 4:46 pm
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Location: HongKong
Dear all,

I want to create an idealized warm ocean eddy (symmetric structure in terms of temperature). I used several temperature profiles to make the initial condition, but the structure was a square area as shown in following figure. Do you have any idea about how to create the initial condition to get a more realistic eddy (circular).

Thanks in advance.

Alex


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PostPosted: Wed Oct 07, 2015 5:17 pm 
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Location: IMS/UAF, USA
This solves a different problem but creates an initial shape with circular symmetry:
Code:
! Linear background
      DO k=1,N(ng)
        DO j=JstrT,JendT
          DO i=IstrT,IendT
            val1 = -0.02*z_r(i,j,k)
            t(i,j,k,1,itemp)=val1
            t(i,j,k,1,isalt)=0.0
          END DO
        END DO
      END DO
      DO k=1,N(ng)
        DO j=JstrT,JendT
            DO i=IstrT,IendT
            val1 = sqrt( ((xr(i,j)-40.e+3_r8)/10000.)**2 + &
     &                   ((yr(i,j)-40.e+3_r8)/10000.)**2 + &
     &                   ((z_r(i,j,k) + 500.)/200.)**2 )
            IF (val1 .le. 1) THEN
              t(i,j,k,1,itemp)=10.
              t(i,j,k,1,isalt)=1.0
            END IF
          END DO
        END DO
      END DO
Did you take geometry courses?


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PostPosted: Thu Oct 08, 2015 8:08 am 
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Joined: Fri Apr 30, 2004 6:41 pm
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Location: IRD, FRANCE
a square vortex is possible, but you need some resonant vortex Rossby waves. See this plot by Schubert et al. (1999). I also heard that G. Roullet (LPO, France) has presented some results at the Ocean Sciences meeting where he could make a square vortex using some flux-corrected advection schemes ...


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File comment: Fig.3 from Schubert et al., JAS, 1999
Schubert_etal_JAS1999_fig3.png
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PostPosted: Fri Oct 09, 2015 6:10 am 
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Joined: Fri Jan 08, 2010 7:22 pm
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Location: Theiss Research
I recall my undergrad adviser (physical oceanography) saying: I am sure you can find a square wave in the ocean. That actually makes sense if one thinks in terms of representing waves as a linear combination of trigonometric functions (Fourier series) -- you get a square with two step functions and you can approximate a step function by adding the right sines and cosines (i.e. the right waves) and in fact you don't even need too many terms in the series to get a decent convergence. Thus in physical ocean it is conceivable that if the right waves add up and you get a square. The question is how much will the square last?

That is a very interesting example Patrick, it proves my adviser right, and it looks like it lasted for about an hour or two ...


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PostPosted: Fri Oct 09, 2015 7:21 pm 
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Location: IMS/UAF, USA
Patrick's example is pretty cool, but Alex could try starting from his square and seeing what happens - might be fun!


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PostPosted: Tue Oct 13, 2015 7:43 am 
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Joined: Tue Oct 08, 2013 4:46 pm
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Location: HongKong
Guys, thanks very much for all your suggestions :D . I will try it.


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