Novel Methods to Observe Heat and Ice in the High Latitudes Using PIES

该项目将开发和测试一种非传统的方法，使用配备压力传感器的反向回声测深仪（pie）来测量高纬度海域、大陆架和峡湾的时变热含量和垂直温度剖面。pie安装在破坏性冰山龙骨下方的海床上，为提高对峡湾动力学和大陆架峡湾相互作用的理解提供了一种有前途且廉价的方法，并将增加高纬度地区的长期监测能力，这些地区偏远和恶劣的条件阻碍了传统的原位观测技术。利用pie来表征高纬度地区的变化是对现有技术的一种新颖的重新利用，但其原理与传统的蓝色水域使用pie的原理相同：由于声速依赖于温度，与pie和海气界面之间反射相关的地底往返声传播时间是中间水柱中热量含量的极好代表。此外，当有冰存在时，海水-冰界面的反射也会被探测到，因此pie也提供了一种在高纬度系统中表征冰成分的方法。在格陵兰东部的Sermilik峡湾进行了为期1年的试验部署，收集了现有的pie数据，并在峡湾和附近的大陆架进行了为期2年的三个pie部署，收集了观测数据，pi建议利用这些数据来开发这些方法。

This project will develop and test a non-traditional method to measure the time-varying heat content and vertical temperature profile in high-latitude seas, shelves, and fjords using pressure-sensor-equipped inverted echo sounders (PIES). PIES, which are installed on the seafloor below the reach of destructive iceberg keels, present a promising and inexpensive way to improve understanding of fjord dynamics and shelf-fjord interactions and will increase long-term monitoring capabilities in high latitudes where remoteness and harsh conditions hamper traditional in situ observation techniques. The use of PIES to characterize variability at high latitudes is a novel repurposing of an existing technology, but rests on the same principle as the traditional blue-water uses for PIES: due to the dependence of sound speed on temperature, the surface-to-bottom round-trip acoustic-travel-time associated with reflections between the PIES and the air-sea interface is an excellent proxy for heat content in the intervening water column. Furthermore, since reflections from seawater-ice interfaces are also detected when ice is present, PIES also provide a means to characterize the ice component in high-latitude systems. The PIs propose to develop these methods with existing PIES data collected in a 1-year test deployment in Sermilik Fjord in eastern Greenland and with observations to be collected in a 2-year deployment of three PIES in the fjord and on the nearby shelf.