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On westward transport processes off central California revealed by RAFOS floats
Author(s) -
Ivanov L. M.,
Collins C. A.,
Margolina T. M.,
Piterbarg L. I.,
Eremeev V. N.
Publication year - 2008
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 - 10.1029/2008gl034689
Subject(s) - geology , geostrophic wind , submarine pipeline , advection , shore , upwelling , eddy diffusion , diffusion , eddy , power law , turbulence , oceanography , geodesy , climatology , meteorology , geography , physics , statistics , mathematics , thermodynamics
Westward transport processes off central California are quantified by exit time statistics for RAFOS floats launched at mid‐depths (275–375 m). The random displacement model in the diffusion limit was used to interpret results. The alongshore‐averaged westward motion of floats represented inhomogeneous eddy diffusion interspersed with short‐duration advective motions. The across‐shore diffusion coefficient grew as a power law with distance from the coastline (the power exponent was close to one). This is evidence for offshore growth of eddy kinetic energy and may be explained through flow barotropization accompanied by a quasi‐geostrophic turbulent regime. Typical values of the float drift velocity were about 1.8–2 cm/s but, offshore, drift velocities were as high as 4–6 cm/s during the upwelling season. Between 150 and 250 km from shore, a transition zone between nearshore and offshore was clearly identified in spring but was either very narrow or undetectable in other seasons.