Conductivity-Temperature-Depth (CTD) Survey in Wolstenholme Fjord, Greenland, April 2017

The principal investigators of this project propose to design and develop an integrated underwater acoustic sensor network for ice-covered seas. The sensor and communication network will support 1) long-term, intelligent distributed Arctic observing systems, 2) assimilation of remote-sensing and in-situ under-ice measurements, and 3) regional and global climate modeling with real-time measurements. Such a network holds the promise to revolutionize under-ice ocean sampling in polar regions. Ocean water properties in Wolstenholme Fjord adjacent to Thule Air Base (TAB) in Greenland were profiled at 68 discrete stations in April 2017. The fjord was covered by land-fast sea ice and thus provided a stable platform from which to test, deploy, and recover a range of oceanographic and acoustic sensor systems via snowmobiles during day-light hours in April when air temperatures are generally above -25 °C. We collected about 4-7 stations per section at ~10 sections that crossed bathymetric features such as entrance channels, basins, and sills. Sections with 1-2 km station spacing were also placed across Moltke, Knud Rasmussen, and Chamberlin Glaciers.本项目首席研究员拟设计并开发一套面向冰覆盖海域的集成化水下声学传感器网络。该传感器与通信网络将支撑三大应用方向：1）长期智能分布式北极观测系统；2）遥感与冰下原位测量数据的同化融合；3）基于实时测量数据的区域及全球气候模式模拟。此类网络有望彻底革新极地地区的冰下海洋采样工作。 2017年4月，研究团队于毗邻格陵兰图勒空军基地（TAB）的沃尔斯特霍姆峡湾（Wolstenholme Fjord）的68个离散测点完成了海水物性剖面观测。该峡湾被固定海冰覆盖，为测试、布放与回收多套海洋学及声学传感器系统提供了稳定平台：研究团队可在4月白天气温普遍高于-25℃的时段，借助雪地摩托开展相关作业。 研究团队在跨越入口水道、海盆与海槛等海底地形特征的约10条测线上，每条测线布设4至7个测点。此外，在莫尔特克冰川（Moltke Glaciers）、克努兹·拉斯穆森冰川（Knud Rasmussen Glaciers）与张伯伦冰川（Chamberlin Glaciers）沿线，还布设了测点间距为1至2公里的测线。