Held-Suarez simulation with idealized Andes

These figures show some results from testing the adaptive-grid dynamics core using the Held-Suarez (1994, BAMS) test case. All runs shown here use a static stretched grid that has 3x longitudinal resolution and 2x latitudinal resolution near the mountain (versus a uniform grid with the same number of grid points). Resolution is correspondingly lower far from the mountain.

The mountain is given by 

     z=(5000 m) exp{-R**4}

            (x-x0)**2     (y-y0)**2
     R**2 = ---------  +  ---------
             sigx**2       sigy**2

     sigx =  5 deg
     sigy = 20 deg
       x0 = 180 deg
       y0 = -20 deg
The mountain is thus long, narrow and located primarily in the southern hemisphere. The only geographical feature in the simulation is the mountain, so the specific location in longitude is irrelevant.

Total vorticity

These two figures show the magnitude of the total vorticity vector for the lowest model layer. It is dominated by the terms involving the vertical shear of the horizontal wind (du/dz and dv/dz) that appear in the two horizontal components of the vector. Since the vector's magnitude is plotted the field is positive everywhere. Contour shading gets lighter with increasing magnitude, so low vorticity regions are dark.


(Download Quicktime animation for a 30-day period.)

Vertical component of vorticity

These two figures show the more familiar (to meteorologists) vertical component of the vorticity vector, at roughly 5 km above the surface. For these figures, positive vorticity has lighter shades, and negative vorticity has darker shades, with vorticity extremes appearing as the lightest and darkest shades, respectively.

Download Quicktime "Andes" region animation for a 30-day period:
  1. .zip file
  2. Stuffit .sit file
  3. Stuffit .sitx file

"Andes" wake flow

The animations show a fairly persistent region of low total vorticity in the near-surface flow at about (-25 deg latitude, 220 deg longitude). This region at 5 km tends to have a quasi-stationary maximum in the vertical component of vorticity. The same features appears at other levels, suggesting a cut-off vorticity max is occurring.

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