冬季大风过程下渤黄海水位低频波动及黄海暖流机制研究
发布时间：2018-11-10 18:50
【摘要】：本文基于观测获得的北黄海水位低频波动和海流震荡现象，结合渤海三个海洋站余水位长期资料和ROMS数值模式，建立了一个能够精确刻画渤黄海冬季水位低频波动和海流震荡现象的数值模型。通过多年份10次水位低频波动过程的模拟和验证，证实了冬季渤黄海水位低频波动并非偶发，而是渤、黄海冬季一种较为常见的水文现象，其减水极值范围最南可达31°N。相对于海表气压、热通量等因素，风应力是造成冬季渤黄海海区水位低频波动主要原因。渤黄海海域（29°N以北，130°以西）的局地风的影响是产生水位波动的必要条件。通过对风向和风区的讨论，沿岸风应力分量最大的西北风对形成渤黄海减水现象更为有利，北风次之，东北风几乎不能形成水位下降。从风区方面来看，渤海、北黄海局地风的影响较小，水位下降的主要原因是南黄海风应力引起的海面变化导致的压强梯度差对海水的抽吸作用。南黄海减水现象主要由局地风的影响控制。渤黄海海域的减水现象同时也受临近黄海的东海上空的风应力的影响。定常风无法激发水位低频波动和海流震荡现象,时变的经向风的影响是极其重要的。 冬季渤黄海水位低频波动是经向风应力引起的海面倾斜与北风松弛后压强梯度力激发的开尔文波共同作用的结果。北风增强的阶段，表现为海面倾斜占优。而在北风松弛的阶段，开尔文波的影响占优，沿西（东）边界向南（北）传播的开尔文波是造成水位变化的主要原因。纬度方向上水深的变化无法改变波动的本质，只对波动的振幅起作用。 海流震荡的本质机制是大风影响下的风海流和大风松弛后激发的沿西（东）岸向南（北）传播的开尔文波的共同作用。海流震荡与水位低频波动被同一机制控制，观测和模拟中水位低频波动和海流震荡耦合发生的现象是由其本质决定的必然结果。作为同种机制的不同表现形式，两者的极值影响范围类似，水位低频波动可以作为海流震荡现象的佐证，这对研究冬季渤黄海环流系统具有十分积极的作用。 冬季黄海暖流并不是北风松弛引起的间歇补偿流，而是具有“稳定模态”和“正压模态”两个模态的较为稳定的流动。在无剧烈的大风过程时，黄海暖流表现为“稳定模态”，而在冬季剧烈的偏北风影响下，“稳定模态”的黄海暖流消失，海流表现为强北风控制表底一致的南向流。大风松弛阶段，黄海暖流表现为表底一致且流速增强的“正压模态”。通过正压模型的分析，海流震荡对边界区高纬度水体的南向移动和中心区低纬度水体的北向移动是有利的。 通过对渤海断面和南、北黄海分界线断面的水通量和盐通量的研究可知，，在发生水位低频波动时，渤海水位下降主要是由水量流失造成的，开尔文波的影响十分微弱。而在水位恢复的过程，盐通量的变化证明高盐的黄海水进入渤海。海流震荡对渤海水交换有显著影响。通过对渤海海洋站多年余水位资料的分析及上文水位低频波动可以作为海流震荡佐证的结论，本文首次以水交换为着眼点进行渤海盐度年变化的分析并作出渤黄海冬季水位低频波动是影响渤海盐度变化的重要因子的推断。
[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 掳 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 掳 N and west of 130 掳) 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
本文编号：2323308
[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 掳 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 掳 N and west of 130 掳) 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
本文编号：2323308
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