EAGER: Collaborative Research: Monitoring Nearshore Ice and Closing the Arctic Tide-gauge Gap with GNSS-Reflectometry (MONICA)

对沿海水位的准确和无缝监测可以通过改进风暴潮预报、为应急反应提供信息、促进安全航行以及改进测绘和制图工作，从而产生经济和社会效益。然而，阿拉斯加西部和北部海岸线上只有有限数量的验潮仪。潮汐测量仪短缺的主要原因是安装和维护的天气条件具有挑战性，以及海冰的季节性存在。与此同时，对沿海海冰的常规监测也是不够的，尽管它在沿海社区捕捞海洋生物和安全航行方面发挥着至关重要的作用。该项目的目的是制定一项高效率和有效的战略，通过检测海冰的存在、陆地冰的开始和脱离以及全年测量水位，来持续监测北极沿海海洋环境。为实现这一目标，该项目打算开发一种全年监测水位和海冰的新技术，方法是对最先进的全球导航卫星系统(GNSS-R)水冰观测系统(GRWIS)进行技术创新。GNSS-R利用GNSS多路径信号，已广泛用于通过测量反射面的几何变化来监测水位。然而，迄今为止探索利用全球导航卫星系统监测海冰的研究相对较少。该项目将利用GNSS-R技术的能力，该技术不仅能够测量反射器高度，而且还可以计算反射器的粗糙度，例如取回的置信度。该项目将研究CLR的优化使用，以确定海冰和陆冰的存在。探测到的冰将通过与实地观测和海冰雷达系统和卫星图像收集的其他数据进行交叉验证来区分陆地冰和公海冰或漂浮冰。此外，GRWIS将监测海冰的垂直和水平运动，而另一项新的冰层监测技术--伽马便携式雷达干涉仪(GPRI)将促进这种冰层监测方法的实施。GPRI将评估和验证GRWIS测量对海冰水平运动的敏感性，这将有助于了解对水位测量的潜在影响，并确定基于GNSS的观测用于评估陆冰稳定性的可行性。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Accurate and seamless monitoring of water levels along the coast can lead to economic and societal benefits by improving storm-surge forecasting, informing emergency responses, promoting safe navigation, and improving mapping and charting efforts. However, only a limited number of tide gauges are located along Alaska’s western and northern coastline. This scarcity of tide gauges is primarily attributed to the challenging weather conditions for installation and maintenance, as well as the seasonal presence of sea ice. Simultaneously, routine monitoring of coastal sea ice is also insufficient, despite its crucial role among coastal communities for harvesting marine wildlife and for safe navigation. The aim of the project is to develop an efficient and effective strategy for continuously monitoring the Arctic coastal marine environment by detecting the presence of sea ice, the onset and detachment of landfast ice, and measuring the water level throughout the year. To achieve this goal, the project intends to develop a novel technology to monitor water level and sea ice year-round by building technical innovations on the state-of-the-art Global Navigation Satellite System (GNSS) Reflectometry, referred to as a GNSS-R Water-Ice observation System (GRWIS).GNSS-R, which utilizes GNSS multipath signals, has become widely employed for monitoring water levels by measuring the geometric variation of reflecting surfaces. However, relatively few studies to date have explored the use of GNSS-R for monitoring sea ice. This project will leverage the capabilities of GNSS-R technique, which not only enables measurements of the reflector heights but also calculates the roughness of the reflector, e.g., the confidence level of retrieval (CLR). This project will investigate an optimized use of CLR to determine the presence of sea ice and landfast ice. The detected ice will be differentiated between landfast from open ocean or drifting ice by cross validating them against field observations and other data collected by sea ice radar systems and satellite imagery. Moreover, the GRWIS will monitor both the vertical and horizontal motion of the sea ice and this ice monitoring method will be facilitated by another novel ice monitoring technology, the Gamma portable radar interferometer (GPRI). The GPRI will assess and validate the sensitivity of GRWIS measurements to horizontal motion of sea ice that will aid in understanding the potential impact on water level measurements and determining the feasibility of GNSS-based observations for assessing the stability of landfast ice.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.