Prof. Ruo-shan Tseng
Prof. Ruo-shan Tseng
National Sun Yat-sen University, Chinese Taipei
Title: Response of ocean-mixed layer current to global typhoons of different intensities
Global data from drifters of Surface Velocity Program and tropical cyclones (TCs) were analyzed to demonstrate strong ocean currents and their characteristics under various storm intensities in the Northern Hemisphere (NH) and in the Southern Hemisphere (SH). Mean TC's translation speed (Uh) is faster in the NH (~4.7 m/s) than in the SH (~4.0 m/s), owing to the fact that TCs are more intense in the NH than in the SH. The rightward (leftward) bias of ocean mixed-layer (OML) velocity occurs in the NH (SH). As a result of this slower Uh and thus a smaller Froude number in the SH, the flow patterns in the SH under the same intensity levels of TCs are more symmetric relative to the TC center and the OML velocities are stronger. This study provides the first characterization of the near-surface OML velocity response to all recorded TCs in the SH from direct velocity measurements.
We also analyzed data from satellite altimeter measurements, satellite-tracked surface drifters and global typhoons from 1993 to 2015 to investigate mesoscale cyclonic eddies induced by slow-moving super typhoons, defined as that the translation speed of typhoon is less than the phase speed of first baroclinic mode in that ocean. Our results show that among 22 slow-moving super typhoons found globally in this period, only seven typhoons produced or strengthened cyclonic eddies (3 in Northern Hemisphere, and 4 in Southern Hemisphere). Comparing to the averaged characteristics of eddies in open oceans, these typhoon-induced eddies had stronger intensity and longer lifespan, especially for the Northwestern Pacific and South Pacific Oceans. Take TC-Nida-eddy for instance, maximum current speeds of over 2 m/s, lifespan of 8 month, temperature drop of 4.5oC and formation of upwelling were observed. A negative correlation is also found between eddy’s EKE and TC’s translation speed.

Ph. D. University of Delaware, USA, Physical Oceanography June 1987
M. S. National Taiwan University, Taiwan, Physical Oceanography June 1978
B.S. National Cheng-Kung University, Taiwan, Naval Architecture and Marine Engineering
June 1976
2013-present: Professor, Department of Oceanography, National Sun Yat-sen University, Taiwan
2004-2013: Professor, Department of Marine Resources, National Sun Yat-sen University, Taiwan
1992-2004: Associate Professor, Department of Marine Resources, National Sun Yat-sen University,
Kaohsiung, Taiwan
1989-1991: Research Associate, RSMAS, University of Miami, USA
1987-1989: Post-doctor, Department of Aerospace Engineering, University of Southern California,
1983-1987: Research Assistant, College of Marine Studies, University of Delaware, USA
1980-1983: Associate Researcher, Energy Research Laboratories, Industrial Technology Research
Institute, Taiwan