From MarineBiotech Infopages
Radiation stress is the flux of momentum, which is carried by the ocean waves. When these waves break, that momentum is transferred to the water column, forcing nearshore currents. Forcing due to these radiation stress gradients is commonly several orders of magnitude greater than forcing due to wind of other wave nonlinearities.
For a more detailed explanation, see Shallow-water wave theory#Radiation Stress (Momentum Flux).
- wikipedia