# Spherical Coordinates¶

## Input for Spherical mode¶

All input parameters, except the following grid information, are the same as for the Cartesian code.

• Lon_West: longitude (degrees) of west boundary.
• Lat_South: latitude (degrees) of south boundary.
• Dphi: $$d\phi$$ (degrees)
• Dtheta: $$d\theta$$ (degrees)

In addition, it is not necessary to specify Gamma2 (for nonlinear dispersive terms) in the spherical code.

Another feature of the spherical code is that a computational grid can be a stretched grid. For a stretched grid, a user should set StretchGrid = T and provide grid files for DX and DY and a file for Coriolis parameters at each grid point. For example,

DX_FILE = dx_str.txt

DY_FILE = dy_str.txt

CORIOLIS_FILE = cori_str.txt

However, use of a stretched grid is not recommended in terms of decrease in numerical accuracy for higher order numerical schemes.