Striations in Marginal Seas and the Mediterranean Sea

• Published in: Geophysical research letters 2019-03, Vol.46 (5), p.2726-2733
• Main Authors: Zhang, Y., Guan, Y. P.
• Format: Article
• Language: English
• Subjects: Banded structure; Barotropic mode; Basins; Cloud bands; Clouds; Cut off wavelength; Earth; Earth atmosphere; filter parameters; Fluid dynamics; Fluid flow; Furrows; Jet stream; Jet streams (meteorology); Jupiter; Jupiter atmosphere; Marginal seas; Ocean basins; Oceans; Planetary rotation; Ridges; Rotating fluids; spatial distribution; Striations; Structures; the Mediterranean sea; Universe; Wavelength; Zonal flow; Zonal flow (meteorology)
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2018GL081050

Striations, which are jet‐like structures comprising alternating ridges and furrows within large‐scale circulations, are widely studied in the open ocean, although it is unclear whether they exist in marginal or semiclosed seas. Based on an appropriate choice of averaging time scale and cutoff wavelength, our analysis reveals striations in marginal seas, including the South China Sea (SCS), Sea of Japan, and Gulf of Mexico, and in the Mediterranean Sea (MS). Compared with the open ocean, these striations have a narrower bandwidth (about 60 km in marginal seas and 100 km in the MS), fewer zonal orientations, stronger baroclinic structure, and deeper intensification. Striations in the open ocean are usually barotropic; however, within the South China Sea and MS, they are baroclinic in the upper 1,000 m and intensified at depths greater than 3,000 m. Plain Language Summary Striped structures are common in the universe, especially in a rotating fluid from atomic to planetary scales. Examples include zonal flow in plasma, the jet stream in Earth's atmosphere, and cloud bands on Jupiter. Comprising quasi‐parallel symmetrical bands, these stripes are a kind of organized structure in complex multiscale and chaotic turbulent flows. In this study, we focus on flow stripes in the ocean that comprise striations; that is, two adjacent flows moving in opposite directions. We consider smaller sea basins such as the South China Sea, the Sea of Japan, the Gulf of Mexico, and the Mediterranean Sea. Compared with the open ocean, we find that striations in these basins are narrower and more complex in their directions. This result can help us understand the diverse structures of ocean striations. Key Points The time scale and cutoff wavelength for detecting striations show clear differences between marginal seas and the open ocean Horizontal and vertical distributions of ocean striations in marginal seas and the Mediterranean sea are presented Striations in marginal seas show a relatively narrow bandwidth, fewer zonal directions, stronger baroclinic structures, and deeper intensification