Andes Simulation Resolution Study

This page describes a set of numerical simulations at progressively coarser resolution to compare with the Andes07 results, which use 500 m isotropic mesh spacing. Four new simulations were conducted, having horizontal resolutions of 1000, 2000, 4000 and 8000 m.

This series utilizes an identical vertical mesh as the original Andes07 run.

Results Comparision with Previous Simulation Andes_Resolution

The vertical mesh is the only difference between these two simulations.
Andes_resolution is followed by the new results for each frame. These samples are for the 2km horizontal mesh siimulation.

u' in an x-y Plane at and Altitude of 70 km.

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u' in an x-z Plane at a Location y = -120 km.

Time = 7.5 hr

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Time = 9 hr

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Time = 12 hr

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Mesh Comparison

Horizontal Spacings

Each computational grid uses the same strategy as in Andes07 with uniform high resolution used over the Andes and then progressively coarser mesh in the horizontal directions when moving towards the lateral boundaries. The white lines in the image below show the region of uniform spacing and this is identical to what was used in the Andes07 simulation. The only difference is that the horizontal spacings in the high-resolution zone is increased from 500 m in the Andes07 simulation to 1000, 2000, 4000, and 8000 m here. The dotted white line in the image below indicates the location of the x-z views shown below.

surface
Region of uniform mesh (solid lines) and x-z plane location (dotted line). (Δ 4000 m case).

Vertical Spacing

Identical to Andes07.

Each computational domain extends to an altitude of 200 km and uses 500 m resolution at the surface to an altitude of 144 km. Very gentle stretching is used to the top of the domain.

Stretching

The the rate at which the mesh is stretched in all three directions is approximately equal ~1.6%, which is nearly identical to what was used in the Andes07 run.

Wind and Thermodynamic Profiles


Forcing

Forcing terms gradually introduce winds near the surface with the objective of achieving the wind profile within a twelve hour period. A hyperbolic tangent function is used in order to produce gentle acceleration of the wind near the beginning and end of the forcing period. The maximum forcing rate is equivalent to that of a linear ramp with a duration of four hours.

The wind profile and forcing strategy are idetical to what was done in the Andes07 run.
winds