Tomographic mapping of a coastal upwelling and the associated diurnal internal tides in Hiroshima Bay, Japan
Tomographic mapping of a coastal upwelling and the associated diurnal internal tides in Hiroshima Bay, Japan
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日本广岛湾沿海上升流和相关的日内潮汐的层析测绘
DOI：
10.1002/2014jc010676
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发表时间：
2015-06-01
影响因子：
3.6
通讯作者：
Gohda, Noriaki
中科院分区：
文献类型：
--
作者：
Zhang, Chuanzheng;Kaneko, Arata;Gohda, Noriaki
通过四个沿海声学断层扫描（CAT）系统测量了广岛湾北部由台风引起的温度变化。 2013年9月11日至25日期间，每隔10分钟绘制了0至8 m深度平均温度的水平分布。利用沿5条成功的声传输线的单向走时数据，通过基于网格分段方法的正则化反演，很好地重建了沿海上升流和相关的日内潮汐的水平分布。站到站范围以这样一种方式进行校正，即声速（根据单向传播时间数据确定）等于根据每条传输线上的几个 CTD（电导率-温度深度）数据集计算出的声速。此外，所有站的位置都进行了调整，以使焦点位于换能器的地理位置上。这些修正提高了温度测量的准确性，使温度误差小至 0.073–0.079°C。高精度使得绘制变化范围小于0.5°C的温度结构成为可能。 9 月 16 日至 17 日，由于台风引发的偏北风，上升流有所增加。日间内潮与半日外潮产生共振，半日外潮在上升流衰减后（9 月 18 日）即大潮发生前后明显。配制上升流和混合级分。随着上升流的增加，这些分数不断增加。在上升流的成熟阶段观察到完全混合。
Temperature variations caused by a typhoon were measured in the northern part of Hiroshima Bay by four coastal acoustic tomography (CAT) systems. The horizontal distributions of depth-averaged temperature from 0 to 8 m were mapped at 10 min intervals between the 11 and 25 September 2013. The horizontal distributions of a coastal upwelling and the associated diurnal internal tides were reconstructed well by regularized inversion based on the grid segmented method, using one-way travel time data along five successful sound transmission lines. Station-to-station ranges were corrected in such a way that sound speed (determined from one-way travel time data) was equal to sound speed calculated from a couple of CTD (conductivity-temperature-depth) data sets on each transmission line. In addition, all station positions were adjusted to make focal points at the geographical positions of the transducers. The corrections increased the accuracy of temperature measurements to make temperature errors as small as 0.073–0.079°C. The high accuracy made it possible to map the temperature structure with a variation range of less than 0.5°C. An upwelling grew from 16 to 17 September, due to a typhoon-derived northerly wind. The diurnal internal tide resonated with the semidiurnal external tide, which was pronounced after the upwelling decayed (18 September), around the time the spring tide occurred. The upwelling and mixing fractions were formulated. These fractions increased continuously as the upwelling grew. Complete mixing was observed during the upwelling's mature phase.