Characterizing Sea Ice Modulations of Seismic Noise using the Alaska Transportable Array

The microseism background seismic wavefield is globally visible across the ≈5-30 s period range. Microseisms are primarily associated with ocean wave energy conversion into globally observable Rayleigh and other wave types within the longer portion of this period range. However, near-coastal ocean and large lake wave processes excite prominent regional shorter-period (≈1-5 Hz) seismic signals that are regionally notable. In polar regions, sea ice prominently modulates microseism power by attenuating ocean wave energy near coastlines across the microseism spectrum (e.g., Aster et al., 2008; Tsai and McNamara, 2011), with particularly strong effects at regionally observed shorter periods.

Using seismic data collected by the Alaska Transportable Array from 2013-2019 and daily sea ice concentration estimated from the Defense Meteorological Satellite Program's SSM/Is and SSMIS passive microwave data, we study the influence of sea ice concentration on seismic noise in northern Alaska, including quantifying and modeling sea ice modulation for stations at various distances from the coast.

We document a very strong anticorrelation between sea ice concentration and daily background noise power between 0.5 and 1 Hz. This frequency is more consistent with studies observing seismic noise in lakes and suggests modifications to traditional ocean microseism theory associated with much shorter period waves and their interactions with shallow water. This characterization and understanding of the mechanism controlling sea ice modulation could provide applications for ground-based remote monitoring of sea ice strength, concentration, stability, and wave energy impacting polar coastal regions.