% geophysical constants in SI units:
 omega = 2*pi/(3600*23+56*60);
 g=9.8;
 a = 6371e3;
 mperdeg = pi*a/180;
 mpernm  = mperdeg/60;  %1852;
 %tidal frequencies: in rad/s
 % in order of amplitude:
 % http://oceanworld.tamu.edu/resources/ocng_textbook/chapter17/chapter17_0
 % 4.htm
M2       = 2*pi/(3600*12.4206);
K1       = 2*pi/(3600*23.9344);
S2       = 2*pi/(3600*12);
O1       = 2*pi/(3600*25.8194);