Beta Effect

The beta effect is the variation of the Coriolis parameter f with latitude, beta = df/dy = 2 Omega cos(phi)/R, where Omega is Earth’s rotation rate, phi latitude, and R Earth’s radius. At midlatitudes beta is about 2 times 10^-11 per meter per second. This planetary vorticity gradient is the restoring mechanism for Rossby waves, forces the westward intensification of ocean gyres (Stommel and Munk theory), and sets the Munk boundary-layer width as (A_h/beta)^(1/3). Without beta, western boundary currents like the Gulf Stream and Kuroshio would not exist.