Separation Rate and Neighbor Diffusivit

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Science  22 Sep 1961:
Vol. 134, Issue 3482, pp. 837-838
DOI: 10.1126/science.134.3482.837


Separation rates of neighboring pieces of orange peel floating on the sea were measured under fresh breeze conditions. When Stommel's equation for neighbor diffusivity (F) was applied to the data it became apparent that the F value increased by an order of magnitude whenever the time adrift increased by this amount. This is a result of the fact that the increase in spacing distance is squared while the time adrift is not. It is recommended that a standard time of 1 second be used whenever Stommel's equation is applied in neighbor diffusivity problems. Recomputation of data from the literature showed that neighbor diffusivity varied between 0.08 and 1 cm2/sec while time adrift varied between 10 and 108 seconds. Further study of separation rates, as parameters of surface turbulence, is recommended.