Anticyclonic precession of a plume in a rotating environment
Geophysical Research Letters
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Frank, D., Landel, J., Dalziel, S., & Linden, P. (2017). Anticyclonic precession of a plume in a rotating environment. Geophysical Research Letters, 44 (18), 9400-9407. https://doi.org/10.1002/2017GL074191
Motivated by potential effects of the Earth's rotation on the Deepwater Horizon oil plume, we conducted laboratory experiments on salt-water point plumes in a homogeneous rotating environment across a wide range of Rossby numbers $0.02<Ro<1.3$. We report a striking physical instability in the plume dynamics near the source: after approximately one rotation period, the plume tilts laterally and starts to precess anticyclonically. The mean precession frequency $\bar\omega$ scales linearly with the rotation rate $\Omega$ as $\bar\omega\approx0.4\Omega$. We find no evidence of a critical Rossby number above which precession ceases. We infer that a conventionally defined Rossby number is not an appropriate parameter when the plume is maintained over a long time: provided $\Omega \neq 0$, rotation is always important to the dynamics. This indicates that precession may occur in persistent oceanic or atmospheric plumes even at low latitudes.
Consortium for Ocean Leadership (via University of Miami) (S1540-664390)
External DOI: https://doi.org/10.1002/2017GL074191
This record's URL: https://www.repository.cam.ac.uk/handle/1810/274640