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        Hello everyone!
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        I'm trying to simulate the ocean circulation under a zonally-symmetric surface temperature forcing in a 2D domain (x-z).
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        Surface temperature is relaxed to a prescribed distribution with a timescale of 20000 s, and Ts ranges from 50 K at the east/west boundaries (±120°) to 3000 K at the substellar point (0°).
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        <strong>But not sure why, the snapshot temperature and other fields (u, SSH, w) always show asymmetric pattern around the substellar point (Figure 1 attached).</strong>
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        <strong>I checked the codes and results, and find that the asymmetric results occur after the rbcs package is included and a condition is added in the </strong><span class="ke-content-forecolor" style="color:#E53333;"><strong>rbcs_add_tendency.F</strong></span><strong>,this condition is added to reduce the velocity to zero when T<1700 K.</strong>
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              IF ( tracerNum.EQ.-2 .AND. useRBCvVel ) THEN<br>
        rec_tauRlx = rbcsVanishingFac/tauRelaxV<br>
        DO j=0,sNy+1<br>
         DO i=0,sNx+1<br>
        <span class="ke-content-forecolor" style="color:#E53333;">IF (theta(i,j,k,bi,bj) .LE. 1700) THEN</span><br>
          gTendency(i,j) = gTendency(i,j)<br>
     &       - RBC_maskV(i,j,k,bi,bj)*rec_tauRlx<br>
     &        *( vVel(i,j,k,bi,bj)- RBCvVel(i,j,k,bi,bj) )<br>
        <span class="ke-content-forecolor" style="color:#E53333;">ENDIF</span><br>
         ENDDO<br>
        ENDDO<br>
      ENDIF<br>
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        And there is no asymmetry when rbcs is Off or rbcs is On and the condition is not included under the same thermal forcing.
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        Actually I can't understand the asymmetry in surface temperature, because it should be the same to the prescribed surface forcing, which should not be affected even by the rbcs package?
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        Do you know how to solve this problem? Any suggestions are welcomed!
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        <span style="font-family:SimSun;text-wrap:wrap;">By the way, there are <strong>large negative vertical velocity in the west and east boundaries (top right panel; w; Figure 1</strong></span><span style="font-family:SimSun;text-wrap:wrap;"><strong>)</strong>, I guess it might be induced by numerical problem.If you know the reason please tell me.</span>
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        T<span style="font-family:SimSun;text-wrap:wrap;">hanks very much in advance!</span>
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        And the data.rbcs and data files I used are listed as below:
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                %%%%%%%%%%%%%%%%%%%% <span class="ke-content-forecolor" style="color:#E53333;">data.rbcs</span>
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                # RBCS package parameters:<br>
 &RBCS_PARM01<br>
 useRBCuVel=.TRUE.,<br>
 useRBCvVel=.TRUE.,<br>
 tauRelaxU=4000.,<br>
 tauRelaxV=4000.,<br>
 relaxMaskUFile='U_relax_mask.bin'<br>
 relaxMaskVFile='V_relax_mask.bin'<br>
 relaxUFile='U_relax.bin',<br>
 relaxVFile='V_relax.bin'
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# Note that U/V_relax_mask = 1.0 everywhere, and U/V_relax = 0.0 everywhere.

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        %%%%%%%%%%%%%%%% some codes in <span class="ke-content-forecolor" style="color:#E53333;">data</span>
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         &PARM01<br>
 tRef=43*50.,<br>
 sRef= 43*34.7,<br>
 cosPower=1.,<br>
 viscAr=1.E-3,<br>
 viscAh=12.E5,<br>
 no_slip_sides=.TRUE.,<br>
 no_slip_bottom=.TRUE.,<br>
 bottomDragLinear=1.E-3,<br>
 diffKhT=1.E3,<br>
 diffKrNrT=43*1.E-3,<br>
 ivdc_kappa=100.,<br>
 implicitDiffusion=.TRUE.,
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        <span style="font-family:SimSun;"> &PARM04</span><br>
<span style="font-family:SimSun;"> usingSphericalPolarGrid=.TRUE.,</span><br>
<span style="font-family:SimSun;"> delRc = 40, 40, 40, 40, 40, 40, 40, 50, 50, 50, 50, 50, 50, 50, 50, 50, 60, 60, 60, 80, 80, 80, 100, 100,</span><br>
<span style="font-family:SimSun;">    100, 100, 100, 100, 100, 100, 150, 150, 150, 200, 200, 200, 200, 200, 300, 300, 300, 300, 400, 400,</span><br>
<span style="font-family:SimSun;"> rSphere=9E6,</span><br>
<span style="font-family:SimSun;"> xgOrigin=-120.,</span><br>
<span style="font-family:SimSun;"> delY=1*2.5,</span><br>
<span style="font-family:SimSun;"> delX=96*2.5,</span><br>
<span style="font-family:SimSun;"> &</span><br>
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<span style="font-family:SimSun;"># Input datasets</span><br>
<span style="font-family:SimSun;"> &PARM05</span><br>
<span style="font-family:SimSun;"> bathyFile='topo_nx96ny1_5km.bin',</span><br>
<span style="font-family:SimSun;"> thetaClimFile='sst_Tm3000K.bin',</span><br>
<span style="font-family:SimSun;"> &</span>
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        <span style="font-family:SimSun;">Best regards,</span>
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        <span style="font-family:SimSun;">Yanhong </span>
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