| 摘要: |
| 作为中尺度过程与小尺度过程中的过渡，次中尺度过程[空间尺度为O（1~10） km，时间尺度为O（1）天]是海洋动力过程中重要的一环。海洋次中尺度过程具有明显的非地转特征，从而促进垂向热量和物质的输运，因此在海洋上层热量与物质垂直交换中肩负着极为重要的作用。黑潮作为全球最强的西边界流之一，是海洋能量的重要聚集区。针对黑潮流区大尺度环流和中尺度涡旋等动力过程的研究，受到海洋和气象学者的广泛关注，但对黑潮流区次中尺度过程的相关研究相对较少。本文基于高分辨率ROMS数值模式（空间分辨率为1公里），针对黑潮流区（25.5°~29.4°N，124.4°~131°E）次中尺度过程的空间分布特征及其诱导的热量输运特征进行了研究。模拟结果表明，黑潮流区存在着十分活跃的次中尺度过程，尤其是在黑潮流区及岛屿周边等地形变化剧烈的海区。相对涡度和垂直流速的分布特征表明，次中尺度相对涡度和垂向流速上表现出了明显的不对称性，正相对涡度强于负相对涡度，向下垂向流速强于向上垂向流速，而这主要是由惯性不稳定所导致。通过计算次中尺度引起的热量输运，结果表明次中尺度的水平热量通量为东北方向，从较低纬度朝较高纬度输运，这意味着次中尺度可以促进不同纬度的热量交换；而垂向热量通量则表现出向上输运的特征，即由深层往表层输运，这意味着次中尺度过程可以导致热量在垂直方向上的再分配，从而使得海洋趋于再分层。 |
| 关键词: 次中尺度 黑潮流区 热量输运 |
| DOI：10.11759/hykx20181220001 |
| 分类号:P733 |
| 基金项目:国家自然科学基金项目（41806025） |
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| Characteristics of submesoscale heat transport in the Kuroshio Current area: results of a case simulationin January 2013 |
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WU Di-xi1,2, DONG Ji-hai1,3, CHEN Zhi-jie2
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1.School of Marine Science, Nanjing University of Information Science and Technology, Nanjing 210044, China;2.Third Institution of Oceanography Ministry of Natural Resources, Xiamen 361000, China;3.Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai), Zhuhai 519000, China
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| Abstract: |
| In the transition between mesoscale and small-scale processes, the submesoscale process[spatial scale of O(1-10)km and time scale of O(1) days] is an important part of oceanic dynamics. Ocean submesoscale processes have obvious non-geostatic characteristics that can induce strong vertical motion, thereby promoting vertical heat and material transport. Therefore, it plays an extremely important role in the vertical exchange of heat and matter in the upper ocean. As one of the strongest western-boundary currents in the world, the Kuroshio is an important gathering area of oceanenergy. Dynamic processes such as largescale circulation and mesoscale eddies in the Kuroshio areas have been of interest to meteorologists and oceanographers. There are relatively few related studies on submesoscale processes in the Kuroshio area. This paper is based on the high-resolution ROMS numerical model (spatial resolution of 1 km). Spatial distribution characteristics of the submesoscale processes in the Kuroshio area and the induced heat transport characteristics were studied. Simulation results showed that there is a very active submesoscale process in the Kuroshio area, particularly in the sea and around the island and areas where the topography dramatically changes. Distribution characteristics of relative vorticity and vertical velocity indicated that the submesoscale was significantly asymmetrical with respect to relative vorticity and vertical velocity. Positive relative vorticity was stronger than negative relative vorticity, and downward vertical velocity was stronger than the upward. This phenomenon is mainly caused by inertial instability. Calculating the heat transport caused by the submesoscale showed that the horizontal submesoscale heat flux was in the northeast direction from the lower latitude to the higher latitude, indicating that the submesoscale can promote the exchange of heat across different latitudes. Vertical heat flux showed characteristics of upward transport from the deep water to the surface, indicating that submesoscale processes can lead to the redistribution of heat in the vertical direction. Hence, it makes the ocean tend to restratification. |
| Key words: submesoscale Kuroshio heat transport |
