Some references on the sphere:

Logically Rectangular Grids and Finite Volume Methods for
PDEs in Circular and Spherical Domains,
by Donna A. Calhoun, Christiane Helzel, and Randall J. LeVeque,
SIAM Review 50 (2008), 723752.

Talk at BIRS, 2008

Logically Rectangular Finite Volume Methods with
Adaptive Refinement on the Sphere,
by M. J. Berger and D. A. Calhoun, and C. Helzel, and R. J. LeVeque
Phil. Trans. R. Soc. A 2009 367, 44834496.
doi: 10.1098/rsta.2009.0168