Seismic Ocean Thermometry Using CTBTO Hydrophones
Seismic Ocean Thermometry Using CTBTO Hydrophones
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DOI：
10.1029/2023jb026687
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发表时间：
2023-09
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影响因子：
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通讯作者：
Wenbo Wu;Zhichao Shen;Shirui Peng;Z. Zhan;J. Callies
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作者：
Wenbo Wu;Zhichao Shen;Shirui Peng;Z. Zhan;J. Callies
由于观测范围有限，监测全球海洋，特别是深海的变暖仍然是一个具有挑战性的采样问题。地震海洋测温（SOT）通过使用海底地震产生的声波（称为T波）推断大尺度平均海洋温度变化，补充了现有的点测量。我们在这里证明，与以前使用的陆基T波站相比，全面禁止核试验条约组织（CTBTO）水听器可以以更高的信噪比记录T波。这使我们能够使用小地震（震级<4.0），它发生的频率比大地震高得多，大大提高了SOT的时间分辨率。我们还发现，陆基T波站和CTBTO水听器的T波走时变化显示出很小但系统的差异，尽管这两个站相距仅约20 km。我们将此特征归因于它们对海洋不同部分进行采样的不同声学模式分量。将SOT应用于东印度洋的两个CTBTO水听器，揭示了十年变暖，季节变化和中尺度涡旋的信号，其中一些在以前可用的温度重建中丢失或低估。这一应用证明了水听器台站在全球SOT中的巨大优势，特别是在地震活动水平较低的地区。
Due to limited observational coverage, monitoring the warming of the global ocean, especially the deep ocean, remains a challenging sampling problem. Seismic ocean thermometry (SOT) complements existing point measurements by inferring large‐scale averaged ocean temperature changes using the sound waves generated by submarine earthquakes, called T waves. We demonstrate here that Comprehensive Nuclear‐Test‐Ban Treaty Organization (CTBTO) hydrophones can record T waves with a higher signal‐to‐noise ratio compared to a previously used land‐based T‐wave station. This allows us to use small earthquakes (magnitude <4.0), which occur much more frequently than large events, dramatically improving the resulting temporal resolution of SOT. We also find that the travel time changes of T waves at the land‐based T‐wave station and the CTBTO hydrophone show small but systematic differences, although the two stations are only about 20 km apart. We attribute this feature to their different acoustic mode components sampling different parts of the ocean. Applying SOT to two CTBTO hydrophones in the East Indian Ocean reveals signals from decadal warming, seasonal variations, and mesoscale eddies, some of which are missing or underestimated in previously available temperature reconstructions. This application demonstrates the great advantage of hydrophone stations for global SOT, especially in regions with a low seismicity level.