【摘要】：本文基于觀測獲得的北黃海水位低頻波動和海流震蕩現(xiàn)象，結合渤海三個海洋站余水位長期資料和ROMS數值模式，建立了一個能夠精確刻畫渤黃海冬季水位低頻波動和海流震蕩現(xiàn)象的數值模型。通過多年份10次水位低頻波動過程的模擬和驗證，證實了冬季渤黃海水位低頻波動并非偶發(fā)，而是渤、黃海冬季一種較為常見的水文現(xiàn)象，其減水極值范圍最南可達31°N。相對于海表氣壓、熱通量等因素，風應力是造成冬季渤黃海海區(qū)水位低頻波動主要原因。渤黃海海域（29°N以北，130°以西）的局地風的影響是產生水位波動的必要條件。通過對風向和風區(qū)的討論，沿岸風應力分量最大的西北風對形成渤黃海減水現(xiàn)象更為有利，北風次之，東北風幾乎不能形成水位下降。從風區(qū)方面來看，渤海、北黃海局地風的影響較小，水位下降的主要原因是南黃海風應力引起的海面變化導致的壓強梯度差對海水的抽吸作用。南黃海減水現(xiàn)象主要由局地風的影響控制。渤黃海海域的減水現(xiàn)象同時也受臨近黃海的東海上空的風應力的影響。定常風無法激發(fā)水位低頻波動和海流震蕩現(xiàn)象,時變的經向風的影響是極其重要的。 冬季渤黃海水位低頻波動是經向風應力引起的海面傾斜與北風松弛后壓強梯度力激發(fā)的開爾文波共同作用的結果。北風增強的階段，表現(xiàn)為海面傾斜占優(yōu)。而在北風松弛的階段，開爾文波的影響占優(yōu)，沿西（東）邊界向南（北）傳播的開爾文波是造成水位變化的主要原因。緯度方向上水深的變化無法改變波動的本質，只對波動的振幅起作用。 海流震蕩的本質機制是大風影響下的風海流和大風松弛后激發(fā)的沿西（東）岸向南（北）傳播的開爾文波的共同作用。海流震蕩與水位低頻波動被同一機制控制，觀測和模擬中水位低頻波動和海流震蕩耦合發(fā)生的現(xiàn)象是由其本質決定的必然結果。作為同種機制的不同表現(xiàn)形式，兩者的極值影響范圍類似，水位低頻波動可以作為海流震蕩現(xiàn)象的佐證，這對研究冬季渤黃海環(huán)流系統(tǒng)具有十分積極的作用。 冬季黃海暖流并不是北風松弛引起的間歇補償流，而是具有“穩(wěn)定模態(tài)”和“正壓模態(tài)”兩個模態(tài)的較為穩(wěn)定的流動。在無劇烈的大風過程時，黃海暖流表現(xiàn)為“穩(wěn)定模態(tài)”，而在冬季劇烈的偏北風影響下，“穩(wěn)定模態(tài)”的黃海暖流消失，海流表現(xiàn)為強北風控制表底一致的南向流。大風松弛階段，黃海暖流表現(xiàn)為表底一致且流速增強的“正壓模態(tài)”。通過正壓模型的分析，海流震蕩對邊界區(qū)高緯度水體的南向移動和中心區(qū)低緯度水體的北向移動是有利的。 通過對渤海斷面和南、北黃海分界線斷面的水通量和鹽通量的研究可知，，在發(fā)生水位低頻波動時，渤海水位下降主要是由水量流失造成的，開爾文波的影響十分微弱。而在水位恢復的過程，鹽通量的變化證明高鹽的黃海水進入渤海。海流震蕩對渤海水交換有顯著影響。通過對渤海海洋站多年余水位資料的分析及上文水位低頻波動可以作為海流震蕩佐證的結論，本文首次以水交換為著眼點進行渤海鹽度年變化的分析并作出渤黃海冬季水位低頻波動是影響渤海鹽度變化的重要因子的推斷。
[Abstract]:Based on the observation of the low-frequency fluctuation of the water level in the North Yellow Sea and the phenomenon of current oscillation, the numerical model of the low-frequency fluctuation and the current oscillation in the winter water level in the Yellow Sea is established by combining the long-term data and the ROMS numerical model of the three marine stations in the Bohai Sea. Through the simulation and verification of the low-frequency fluctuation of the water level in the multi-year period, it is proved that the low-frequency fluctuation of the water level in the Yellow Sea during the winter is not an accident, but a more common hydrological phenomenon in the Yellow Sea and the Yellow Sea. The extreme range of the water-reducing extreme value can reach 31 擄 N. Relative to the air pressure and heat flux of the sea surface, The wind stress is the main cause of the low-frequency fluctuation of the water level in the Yellow Sea area during the winter. The effect of local wind on the sea area of the Yellow Sea (north of 29 擄 N and west of 130 擄) is the necessary condition for water level fluctuation. Through the discussion of the wind direction and the wind area, the northwest wind with the largest coastal wind stress component is more favorable to the formation of the Yellow Sea water-reducing phenomenon, the north wind is the second, and the northeast wind can hardly form a water level drop. From the aspect of the wind, the influence of the local wind of the Bohai Sea and the North Yellow Sea is small, and the main reason for the decrease of the water level is the pressure gradient caused by the wind stress in the South Yellow Sea and the pumping action of the sea water. The water-reducing phenomenon of the South Yellow Sea is mainly controlled by the local wind. The water-reducing phenomenon in the sea area of the Yellow Sea is also affected by the wind stress above the East China Sea in the Yellow Sea. The steady wind can not stimulate the low-frequency fluctuation of the water level and the current oscillation phenomenon, and the influence of the time-varying wind on the wind is extremely important. The low-frequency fluctuation of the water level in the Yellow Sea during the winter is co-acting with the Kelvin wave excited by the pressure gradient after the wind stress is induced by the wind stress and the relaxation of the north wind As a result, the north wind enhanced stage, manifested as a sea-surface tilt. In the stage of the north wind relaxation, the influence of the Kelvin wave is dominant, and the Kelvin wave which is spread to the south (north) along the west (east) boundary is the main cause of the change of the water level Cause. The change in water depth in the latitudinal direction cannot change the nature of the wave, only to the amplitude of the wave. The essential mechanism of the current oscillation is the wind current under the influence of strong wind and the Kelvin wave which is excited by the wind current and the strong wind in the west (east) to the south (north). The co-action of the current oscillation and the low-frequency fluctuation of the water level is controlled by the same mechanism, and the phenomenon of low-frequency fluctuation of the water level in the observation and simulation and the coupling of the current oscillation is determined by its nature As a result of the different expression of the same mechanism, the extreme influence range of the two is similar, and the low-frequency fluctuation of the water level can be used as the proof of the current oscillation phenomenon, which is very important to the study of the Huanghai Huanghai circulation system in winter The warm current of the Yellow Sea in winter is not the intermittent compensation flow caused by the relaxation of the north wind, but it has two modes of 鈥渟table mode鈥

本文編號：2323308