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Horizontal dispersion in the sea caused by recurring changes of the depth of the wind drift
Author(s) -
Nerheim Signild,
Stigebrandt Anders
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl026212
Subject(s) - advection , geology , wind speed , dispersion (optics) , mode (computer interface) , tracer , surface layer , meteorology , atmospheric sciences , mechanics , physics , layer (electronics) , optics , oceanography , materials science , computer science , nuclear physics , composite material , thermodynamics , operating system
This paper explores a new horizontal dispersion mechanism due to recurrent changes of the depth of the wind drift. In the shallow mode, the wind drift moves the upper part of the surface layer relative to the lower part, giving an increased horizontal area being covered by a tracer present in the layer. When returning to the deep mode, the accompanying vertical mixing increases the volume of the cloud. The rate of increase of the tracer cloud area is proportional to the wind drift velocity in the shallow mode and the area itself, and therefore proportional to the elapsed time squared t 2 . The t 2 ‐law is demonstrated by a numerical experiment and supported by published experimental results. The quadratic dependence is explained by the larger and larger exposure to wind driven advection and not by larger and larger scales of motions taking part in the process known from eddy dispersion.