王冑2006-08-232018-06-282006-08-232018-06-282002http://ntur.lib.ntu.edu.tw//handle/246246/29329這幾年來我們分別在恆春海脊、恆春半島東側、高台石海脊等處設置了海流、水位等的長期錨碇觀測站，另外也藉航次之便順道執行了網狀水文觀測。歷年觀測資料顯示恆春半島東側海域下層海流多為向南，而上層海流在東北風作用後往往亦由北轉為向南，ADCP錨碇觀測資料則顯示：在蘭嶼與屏東間黑潮流動海域之低頻海流會隨著深度增加其流向呈反鐘向迴轉趨勢，表示中、下層海流具有向岸(恆春半島東側)分量。這些觀測事實說明沿著台灣東南陸棚上存有南向之反流，反流東側則為北上之黑潮支流，故在台灣與蘭嶼、綠島間的南縱海槽內海洋上層會呈現氣旋型環流，而由呂宋海峽北上之黑潮支流中、下層海水則在接近海槽南側時向東偏轉，再沿蘭嶼、綠島間海脊東側北上。這種流況是經由海流與地形交互作用所造成的，中、下層海流在南縱海槽內發生流線分離，而上層海流仍沿台灣東南海岸北上，後項海流西側之氣旋型流速水平切變則對本地中、下層海水透過Ekman pumping造成拉升效應，促成南縱海槽內形成持續性之低壓型環流。此機制可以合理解釋台東外海為何會出現持續性的反流。During past years, we have deployed current-meters and water level recorders at several prescribed strategic locations, such as Heng-Chuen Ridge, east of Heng-Chuen, and Gordi Rock. In addition to these works, extensive CTD surveys had been conducted in the region too. These data show that the principal direction of flows at the lower layer offshore the eastern Heng-Chuen peninsula is mainly southward, same behavior was found for flows at the upper layer under prevailing northeastly winds. Aside from this, measurements from ADCP moorings, between Lan-Yu and Ping-Tung, show sub-inertial flows deflecting counter clockwisely with the increment of depth, this characteristic implies the lower currents possessing an on-shore component which should induce upwelling motions in the adjacent of continental margin. All of these suggest flow-topographic interactions are principal mechanisms to the flow pattern. The basin between Taiwan, Lan-Yu and Lu-Tao, blocking the lower northward flows, forms a flow-separation region to the inflow waters, which deflects to the east when approach to the basin. Upper layer flows could pass the basin and the cyclonically horizontal current shear associated with the current favors the emergence of a cyclonic circulation pattern along the southeast coast of Taiwan. The mechanism can interpret the occurrence of a steady counter current offshore Taitung coast, readily.application/pdf114213 bytesapplication/pdfzh-TW國立臺灣大學海洋研究所黑潮反流低壓環流current-metersflow-topographic interactionscounter currentcyclonic circulationreporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/29329/1/902611M002017OP2.pdf