Global Observation of Coastal Waves Using ICESat-2 Photon-Counting LiDAR Data

Abstract

Coastal waves play a vital role in shaping nearshore environments. However, there are still challenges in global wave observation, due to the scarcity of in situ data and the imaging constraints of radar-based remote sensing in coastal areas. Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2’s) photon-counting laser altimeter provides a groundbreaking approach, delivering high-resolution along-track sea surface elevation data to characterize waves globally. We propose a new workflow that infers reliable wave directions by combining cross-track correlation analysis with frequency-based statistical aggregation, and separates wind sea and swell using generalized Fourier transform (GFT) and surface wind data. The results obtained across nine diverse coastal sites show that this new ICESat-2 workflow reliably captures wave directions, significant wave heights, and periods. The method also identifies regional variations in wave spectra and quantifies wind effects on observed signals. This study demonstrates the potential of ICESat-2 for global coastal wave monitoring and fills the critical gaps in the existing observational frameworks.