Movement of oil on the sea surface

The physical processes whereby momentum is transferred from the atmosphere to the sea is discussed in relation to the transport of oil by sea surface motions. It is shown that, in agreement with theory, drift values obtained by small free surface floats exceed that of oil by an amount consistent with the wave transport of typically short crested seas. Oil moves in the direction of the geo strophic wind, ie along the isobar and at 2.75 to 2.3% of the wind speed at 10 m over the sea. The recommended variation of this ratio with wind speed is given. There is some evidence that capillary wave growth commencing at a friction velocity of 23 cms-1 and a surf ace drift near 15 cms-1 is critical to both the aerodynamic roughness and to the dynamic roughness of the water flow. It must be concluded that pollution by surface active agents add yet another variable to the interpretation of stress-wind relationships determined in enclosed or near city coastal waters.