教師著作

Permanent URI for this collectionhttp://rportal.lib.ntnu.edu.tw/handle/20.500.12235/37078

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Author: search.filters.author.L.-Y. OeySubject: search.filters.subject.Kuroshio

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    Air-sea interaction between Tropical Cyclone Nari and Kuroshio
    (American Geophysical Union (AGU), 2008-06-01) Wu, C.-R.; Y.-L. Chang; L.-Y. Oey; C.-W.J. Chang; Y.-C. Hsin
    The air-sea interaction between tropical cyclone Nari (Sep/6 – 16/2001) and Kuroshio is studied using satellite observations and an ocean model. Nari crossed the Kuroshio several times, which caused variations in typhoon intensity. Nari weakened when it was over the shelf north of Kuroshio where cooling took place due to mixing of the shallow thermocline. The cyclonic circulation penetrated much deeper for the slowly-moving storm, regardless of Nari’s intensity. Near-inertial oscillations are simulated by the model in terms of the vertical displacement of isotherms. The SST cooling caused by upwelling and vertical mixing is effective in cooling the upper ocean several days after the storm had passed. At certain locations, surface chlorophyll-a concentration increases significantly after Nari’s departure. Upwelling and mixing bring nutrient-rich subsurface water to the sea surface, causing enhancement of phytoplankton bloom.
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    Bimodal Behavior of the Seasonal Upwelling off the northeastern coast of Taiwan
    (American Geophysical Union (AGU), 2009-03-01) Chang Y.-L.; C.-R. Wu; L.-Y. Oey
    Observations over the outer shelf and shelf break off the northeastern coast of Taiwan indicate a curious seasonal variability of upwelling. At deeper levels 100 m below the surface, upwelling is most intense in summer but weaker in winter. Nearer the surface at approximately 30 m below the surface, the opposite is true and the upwelling is stronger in winter than in summer. Results from a high-resolution numerical model together with observations and simple Ekman models are used to explain the phenomenon. It is shown that the upwelling at deeper levels (∼100 m) is primarily induced by offshore (summer) and onshore (winter) migrations of the Kuroshio, while monsoonal change in the wind stress curl, positive in winter and negative in summer, is responsible for the reversal in the seasonal variation of the upwelling near the surface (∼30 m). This mechanism reconciles previous upwelling data.