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

对沿海沿着水位进行准确和无缝的监测，可以改善风暴潮预报，为应急反应提供信息，促进安全航行，并改善绘图和制图工作，从而带来经济和社会效益。然而，只有有限数量的验潮仪位于沿着阿拉斯加的西部和北方海岸线。验潮仪的稀缺主要是由于安装和维护的恶劣天气条件以及海冰的季节性存在。与此同时，对沿海海冰的例行监测也不够，尽管这对沿海社区捕获海洋野生生物和安全航行至关重要。该项目的目的是制定一项切实有效的战略，通过探测海冰的存在、陆地坚冰的形成和脱落以及测量全年的水位，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新技术，通过在最先进的全球导航卫星系统反射计（称为GNSS-R水冰观测系统）上建立技术创新，全年监测水位和海冰。已经广泛用于通过测量反射表面的几何变化来监测水位。然而，迄今为止探索使用全球导航卫星系统R监测海冰的研究相对较少。该项目将利用GNSS-R技术的能力，该技术不仅可以测量反射器高度，还可以计算反射器的粗糙度，例如，检索的置信水平（confidence level of retrieval，简称CRE）。该项目将研究如何最佳地利用海冰来确定海冰和陆固冰的存在。将根据实地观测和海冰雷达系统和卫星图像收集的其他数据对探测到的冰进行交叉验证，以区分陆地固定冰和公海冰或漂流冰。此外，GRWIS将监测海冰的垂直和水平运动，另一种新的冰监测技术，伽马便携式雷达干涉仪（GPRI）将促进这种冰监测方法。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的观测用于评估陆地固定冰稳定性的可行性。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

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.