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The Effect of Barotropic and Baroclinic Tides on Three‐Dimensional Coastal Dispersion
Author(s) -
Suanda Sutara H.,
Feddersen Falk,
Spydell Matthew S.,
Kumar Nirnimesh
Publication year - 2018
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 - 10.1029/2018gl079884
Subject(s) - baroclinity , barotropic fluid , drifter , dispersion (optics) , geology , internal tide , oceanography , ocean dynamics , mixing (physics) , ocean current , internal wave , physics , lagrangian , quantum mechanics , optics , mathematical physics
The effects of barotropic and baroclinic tides on three‐dimensional (3‐D) coastal dispersion are examined with realistic, 200‐m horizontal resolution simulations of the Central Californian continental shelf during upwelling. Over multiple tidal cycles, the horizontal relative dispersion and vertical dispersion of 3‐D drifters are similar between simulations with no tides and with barotropic tides. In contrast, baroclinic tides, which dissipate across the shelf and induce vertical mixing, result in a factor of 2–3 times larger horizontal and vertical dispersion. The increase in horizontal dispersion with vertical mixing is qualitatively consistent with weak‐mixing shear dispersion. Without shear dispersion, horizontal dispersion of surface‐trapped (2‐D) drifters was similar in all simulations. However, 2‐D drifter trajectory differences relative to no tide simulations are 3–4 times larger with baroclinic tides than barotropic tides alone. These results demonstrate the need to include baroclinic tides and 3‐D tracking for coastal passive tracer dispersion.