Microseismic Remote Sensing of Sea Ice: Exploratory Study on the
Potential Uses of the EarthScope Transportable Array in the Detection of
Sea Ice Dynamics
Abstract
Over recent years, remote sensing of sea ice has advanced at a rapid
pace. However, there are inherent limitations in the ability of existing
space and airborne sensors to observe changes in the properties of
near-shore sea ice, especially over short (hourly) time scales. This
information is of critical importance to the livelihood of local
communities and to meteorologists who depend on knowledge of near-shore
ice conditions for weather prediction. The use of near-real-time data
from coastal seismic arrays promises to advance coastal ice observations
by measuring the amplitude of background seismic noise, known as
microseism. The microseism signal is generated by interactions between
oceanic waves, the ocean floor, and the shoreline. Previous studies have
shown that along polar coastlines the microseism is modulated by the
presence of sea ice. In this feasibility study, we explore the use of
power spectral density (PSD) measurements from the Utqiagvik station of
the EarthScope Transportable Array (TA) to provide information about sea
ice conditions off the northern coast of Alaska. PSD signals are
compared with daily estimates of near-shore ice extent and concentration
within the Beaufort and Chukchi seas. These are derived from satellite
passive microwave radiometer data as well as visible and short-wave
infrared imagery from the Moderate Resolution Imaging Spectroradiometer
(MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS)
instruments. The amplitude of microseism at a frequency near 1 Hz is
statistically correlated with ice coverage to determine if microseismic
signals from a coastal station can be used to reliably identify
particular ice events, including the onset date of summer melt, fast-ice
breakup and formation, and the development of near-shore flaw-leads and
polynas. Data from the Utqiagvik TA station is compared with
observations from other northern coastal stations to determine if sea
ice related microseismic signals are consistent across a range of
geological and topographical environments. The expansion of the
EarthScope TA seismic network to the Arctic coastline since 2011
presents a developing approach to sea ice observation. In the future it
may complement established remote sensing techniques to provide a more
complete picture of coastal ice conditions as they evolve.