Submesoscale transition from geostrophic flows to internal waves in the northwestern Pacific upper ocean

Type Article
Date 2017-01
Language English
Author(s) Qiu Bo1, Nakano Toshiya2, Chen Shuiming1, Klein Patrice3, 4, 5
Affiliation(s) 1 : Univ Hawaii Manoa, Dept Oceanog, 1000 Pope Rd, Honolulu, HI 96822 USA.
2 : Japan Meteorol Agcy, Global Environm & Marine Dept, Chiyoda Ku, 1-3-4 Otemachi, Tokyo 1008122, Japan.
3 : Ifremer CNRS UBO IRD, Lab Oceanog Phys & Spatiale, F-29280 Plouzane, France.
4 : CALTECH, Environm Sci & Engn, Pasadena, CA 91125 USA.
5 : NASA, JPL, Pasadena, CA USA.
Source Nature Communications (2041-1723) (Nature Publishing Group), 2017-01 , Vol. 8 , N. 14055 , P. 1-10
DOI 10.1038/ncomms14055
WOS© Times Cited 47
Abstract With radar interferometry, the next-generation Surface Water and Ocean Topography satellite mission will improve the measured sea surface height resolution down to 15 km, allowing us to investigate for the first time the global upper ocean variability at the submesoscale range. Here, by analysing shipboard Acoustic Doppler Current Profiler measurements along 137 degrees E in the northwest Pacific of 2004-2016, we show that the observed upper ocean velocities are comprised of balanced geostrophic flows and unbalanced internal waves. The transition length scale, L-t, separating these two motions, is found to depend strongly on the energy level of local mesoscale eddy variability. In the eddy-abundant western boundary current region of Kuroshio, L-t can be shorter than 15 km, whereas L-t exceeds 200 km along the path of relatively stable North Equatorial Current. Judicious separation between the geostrophic and internal wave signals represents both a challenge and an opportunity for the Surface Water and Ocean Topography mission.
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