Building Capacity to Measure and Assess Offshore, Full-frequency Water Level Fluctuations to Support Coastal Hazard Observation and Prediction

High-frequency water level fluctuations (HFWLF), such as infragravity waves, meteotsunamis, and wind-generated waves, are significant coastal hazards for the Great Lakes and coastal communities. These fluctuations occur over periods of 30 seconds to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{1 2}$</tex> minutes and impact infrastructure, navigation, and public safety. Current observational networks struggle to capture these events, especially in the infragravity frequency band (30 seconds to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{5}$</tex> minutes), due to limitations in monitoring systems and numerical models. To address this gap, we deployed an innovative network of Sofar Ocean's Spotter buoys with bottom-mounted pressure sensors, sampling at 2 Hz. This network provides high-resolution data across Lake Michigan, Lake Huron, and Lake Superior, enabling detailed analysis of HFWLF. By detecting water level oscillations at unprecedented frequencies, we identify infragravity waves, meteotsunamis, and wind waves, often overlooked in previous efforts. Our analysis focuses on multiple Great Lakes locations, examining temporal and spatial characteristics of these fluctuations. We study event persistence, amplitude, duration, and frequency, linking them with local meteorological conditions and coastal processes. This data enhances risk assessment and forecasting of coastal hazards like erosion, flooding, and structural damage. Ultimately, integrating high-frequency data into operational models improves early detection and mitigation of HFWLF events, supporting infrastructure resilience and public safety in the Great Lakes region.