Bassett Christopher, Lavery Andone C, Lyons Anthony P, Wilkinson Jeremy P, Maksym Ted
Applied Physics Laboratory, University of Washington, 1013 Northeast 40th Street, Seattle, Washington 98105, USA.
Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
J Acoust Soc Am. 2020 Feb;147(2):824. doi: 10.1121/10.0000619.
Accurate measurements of sea ice thickness are critical to better understand climate change, to provide situational awareness in ice-covered waters, and to reduce risks for communities that rely on sea ice. Nonetheless, remotely measuring the thickness of sea ice is difficult. The only regularly employed technique that accurately measures the full ice thickness involves drilling a hole through the ice. Other presently used methods are either embedded in or through the ice (e.g., ice mass balance buoys) or calculate thickness from indirect measurements (e.g., ice freeboard from altimetry; ice draft using sonars; total snow and ice thickness using electromagnetic techniques). Acoustic techniques, however, may provide an alternative approach to measure the total ice thickness. Here laboratory-grown sea ice thicknesses, estimated by inverting the time delay between echoes from the water-ice and ice-air interfaces, are compared to those measured using ice cores. A time-domain model capturing the dominant scattering mechanisms is developed to explore the viability of broadband acoustic techniques for measuring sea ice thickness, to compare with experimental measurements, and to investigate optimal frequencies for in situ applications. This approach decouples ice thickness estimates from water column properties and does not preclude ice draft measurements using the same data.
准确测量海冰厚度对于更好地理解气候变化、在冰封海域提供态势感知以及降低依赖海冰的社区面临的风险至关重要。然而，远程测量海冰厚度却很困难。唯一能准确测量整个冰厚的常规技术是在冰上钻孔。目前使用的其他方法要么是嵌入冰中或穿过冰（例如冰质量平衡浮标），要么是通过间接测量来计算厚度（例如利用测高法测量冰面干舷；使用声纳测量冰下深度；使用电磁技术测量积雪和冰的总厚度）。然而，声学技术可能提供一种测量冰总厚度的替代方法。在此，通过对来自水 - 冰界面和冰 - 空气界面回声之间的时间延迟进行反演来估计实验室培育的海冰厚度，并将其与使用冰芯测量的厚度进行比较。开发了一个捕捉主要散射机制的时域模型，以探索宽带声学技术测量海冰厚度的可行性，与实验测量结果进行比较，并研究现场应用的最佳频率。这种方法将冰厚度估计与水柱特性解耦，并且不排除使用相同数据进行冰下深度测量。
