SPRD6 Model Coefficients 
SPRD6 contains 3D models of shearwave velocity, compressionalwave velocity, and density within the mantle and 2D models of topography on the freesurface (dynamic), the 660km discontinuity, and the coremantle boundary. The 3D models are parameterised in terms of spherical harmonics laterally (up to degree 6) and Chebyshev polynomials radially (up to order 13).
There are two spherical harmonic conventions used. One is the fully normalised "complex" spherical harmonics (Edmonds, 1960) and the other is the "real" spherical harmonics in which most Harvard 3D model coefficients are given (e.g., Su & Dziewonski, 1997). Model coefficients are available in both conventions.
The model coefficients are given in relative perturbations (delta x/x).
For convenience, there is also a tar file (plot_sprd6.tar) which contains files of model coefficients, FORTRAN programs and a README file.
The files (except for those containing real spherical harmonic coefficients of 3D models) contain
k

l

m

model (real/cosine)

model (imaginary/sine)

where k is the order of the Chebyshev polynomial, l is the spherical angular degree and m is the angular order. For 2D models, the k values are not included.

FORTRAN Programs 
There are 5 FORTRAN source codes (which have to be compiled once they are transferred to your machine).
 plot.f
This program reads a model (either 3D or 2D) and outputs a file (with specified name) which contains longitude, latitude and value of the model. For 3D models, the values are in percentage, and for 2D models, the values are in kilometres. The increment of latitude/longitude can be changed by changing the value of parameter "block_size".
In order to run this program, one needs all the following subroutines and also 3D models (in real spherical harmonics  sprd6_s, sprd6_p, and sprd6_r) and 2D models (in complex spherical harmonics  sprd6_fs.XCS, sprd6_d660.XCS, and sprd6_dcmb.XCS).
 sub_chebyshev.f
This subroutine calculates the values of Chebyshev polynomials at a given depth (within the mantle) with appropriate normalisation as discussed in Su (1992).
 sub_kernel.f
This subroutine builds a matrix that contains values of (real) spherical harmonics at each latitude and longitude.
 sub_readModel.f
This subroutine reads a file containing model coefficients and converts them (if necessary) into appropriate spherical harmonics convention to be consistent with spherical harmonic convention used to create the matrix by the subprogram sub_kernel.f.
 sub_switchLatLon.f
This subroutine switches latitude and longitude of the data vector so that the output file (from plot.f) will contain values of longitude, latitude and model.
 Makefile
If one prefers, download this file and type
make plot
to compile plot.f with its subroutines (all the FORTRAN codes must be in the same directory). Then, typing
plot.ex
will run the program plot.f.

References 

Edmonds, A.R., 1960.
Angular Momentum in Quantum Mechanics,
Princeton Univ. Press, Princeton, N.J.

Ishii, M., and Tromp, J., 1999.
Normalmode and freeair gravity constraints on lateral variations in velocity and density of Earth's mantle.
Science 285, 12311236.

Ishii, M., and Tromp, J., 2001.
Evendegree lateral variations in the Earth's mantle constrained by free oscillations and the freeair gravity anomaly.
Geophys. J. Int., 145, 7796.

Su, W.J., 1992.
The ThreeDimensional ShearWave Velocity Structure of the Earth's Mantle.
Ph.D. Thesis, Harvard Univ.

Su, W.J., and Dziewoński, A.M., 1997.
Simultaneous inversion for 3D variations in shear and bulk velocity in the mantle.
Phys. Earth Plnet. Inter. 100, 135156.

Back to Downloads (ThreeDimensional Mantle Models)
Department of Earth and Planetary Sciences / Harvard University / 20 Oxford Street / Cambridge / MA 02138 / U.S.A. /
Telephone: +1 617 495 2350 / Fax: +1 617 496 1907 / Email: reilly@eps.hartvard.edu


