Planetary topography data archive

These files are in ascii format, with each line containing l, m, Clm, Slm where l is the spherical harmonic degree, m is the spherical harmonic order, and Clm and Slm are the real spherical harmonic cosine and sine coefficients, respectively. Alternatively, using the notation where the sine coefficients are assigned to negative angular orders, each line corresponds to l, m, Clm, Cl, -m. The spherical harmonic coefficients are to be used with the "geodesy" 4π normalized spherical harmonics (excluding the Condon-Shortley phase) and are expressed in units of meters. All models were constructed by first obtaining an N x 2N equally spaced grid of global planetary radii in planetocentric coordinates, and then using the sampling theorem of Driscoll and Healy (1994) to compute the spherical harmonic coefficients. These grids include the north pole and 0° longitude, but not the south pole and 360° longitude. When N is even, the spherical harmonic transform is exact if the function is bandlimited to degree N/2-1. These calculations were performed using the SHTOOLS routine SHExpandDH. Details specific to each model are given below and in Wieczorek (2007).