Acoustical survey of methane plumes using the quantitative echo sounder in the eastern margin of the Sea of Japan
Acoustical survey of methane plumes using the quantitative echo sounder in the eastern margin of the Sea of Japan
复制标题
使用日本海东缘定量回声测深仪对甲烷羽流进行声学调查
DOI：
10.1109/oceans.2004.1405646
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Y. Kawada
中科院分区：
文献类型：
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作者：
C. Aoyama;R. Matsumoto;Y. Okuda;Y. Ishida;A. Hiruta;M. Sunamura;H. Numamani;H. Tomaru;G. Snyder;J. Komatsubara;R. Takeuchi;M. Hiromatsu;D. Aoyama;Y. Koike;S. Takeda;T. Hayashi;H. Hamada;Y. Kawada
研究和培训车Umitaka-Maru于2004年7月至8月航行到日本海东部边缘一个小山脊上的甲烷渗漏区，使用定量回声测深仪调查海底甲烷水合物和甲烷羽流的相关声学特征[C.Ayama等人，(2004年)]。我们使用定量回声测深仪和来自GPS的定位数据进行了高分辨率的甲烷羽流测绘，并通过回波积分器测量了每100米距离和每一分钟的甲烷羽流的平均回波强度。我们从目前的回声测深仪调查中得到了一些有趣的结果。我们在超声图像上记录了36个甲烷羽流，直径约100m，高度200~700m，到达海平面以下300~600m，并测量了每个甲烷羽流的积分体积后向散射强度(SV)。羽流中最强的SV为-33dB，强于鱼群的SV。平均Sv在羽流底部和中部附近有最大值，而在羽流顶部则相对较低。我们在观察到甲烷羽流的区域通过活塞取芯找到了几块拳头大小的甲烷水合物。在两米长的活塞岩心区间内发现了甲烷水合物，这表明甲烷水合物沉积在甲烷羽流附近的浅层沉积物中。作为后续项目，我们计划通过在大型水箱中进行实验研究，测量漂浮在水柱中的甲烷气泡和甲烷水合物的SV。
Research and training vehicle Umitaka-maru sailed to the methane seep area on a small ridge in the eastern margin of the Sea of Japan on July to August 2004 to survey the ocean floor methane hydrate and related acoustic signatures of methane plumes using a quantitative echo sounder [C. Aoyama et al., (2004)]. We carried out high-resolution mapping of methane plumes using a quantitative echo sounder with positioning data from GPS and also measured averaged echo intensity from the methane plumes both in every 100 m range and every one minute by the echo integrator. We obtained a number of interesting results from the present echo-sounder survey. We registered 36 plumes on echogram, ranging about 100m in diameter and 200 m to 700 m in height, reaching up to 300 m to 600 m below sea level and measured the integrated volume backscattering strength (SV) of each methane plume. The strongest SV, -33 dB, of the plumes was stronger than SV of fish school. Averaged SV tend to show the highest values around the bottom and the middle of plumes, whereas the SVs are relatively low at the top of plumes. We recovered several fist-sized chunks of methane hydrate by piston coring at the area where we observed methane plumes. Methane hydrate was recovered throughout two meters-long piston core interval, indicating thick hydrate deposits in shallow sediments near the methane plumes. A follow-up project, we are planning to measure SV of methane bubbles and methane hydrate floating in water columns through an experimental study in a large water tanks.