--------------------------------------------------------------------
The files contain phase- and group-velocity maps generated from
the Global Dispersion Model GDM52.

The data set and the model are described in the GDM52 paper:
Ekstrom, G., A global model of Love and Rayleigh 
surface-wave dispersion and anisotropy, 25-250 s,
Geophy. J. Int., doi:10.1111/j.1365-246X.2011.05225.x

There is a separate file for phase and group velocity at
each period and for each wave type (L or R).

Files whose names start with a 'G' contain maps of
group velocity; those whose names start with 'R' or 'L'
contain maps of phase velocity.

Each file contains a line close to the beginning that looks
like 
#GVEL0: xxx.xx
or
#PVEL0: xxx.xx
This line gives the reference phase or group velocity
for the percent-anomaly values that follow.

The files contain values of phase or group velocity,
evaluated from the splined model GDM52 at discrete points on
a one-degree grid.

For Love waves, isotropic variations are given in percent.
The format of the data is 
latitude, longitude, pixel size in degrees, isotropic deviation

For Rayleigh waves, isotropic and anisotropic variations are given
in percent.
The format of the data is
latitude, longitude, pixel size in degrees, isotropic variation,
cosine component of 2-zeta variation, 
sine component of 2-zeta variation (where zeta is the azimuth
of propagation measured from North).

The pixel map is referenced to geocentric coordinates.
--------------------------------------------------------------------
GE 2011-10-25
--------------------------------------------------------------------