Near-surface environmentally forced changes in the Ross Ice Shelf observed with ambient seismic noise

Continuous seismic observations across the Ross Ice Shelf reveal ubiquitous ambient res-
onances at frequencies >5 Hz. These firn-trapped surface wave signals arise through wind
and snow bedform interactions coupled with very low velocity structures. Progressive and long-term spectral changes are associated with surface snow redistribution by wind
and with a January 2016 regional melt event. Modeling demonstrates high spectral sen-
sitivity to near-surface (top several m) elastic parameters. We propose that spectral peak changes arise from surface snow redistribution in wind events, and to velocity drops re-
flecting snow lattice weakening near 0◦C for the melt event. Percolation-related refrozen
layers and layer thinning may also contribute to long-term spectral changes after the melt
event. Single-station observations are inverted for elastic structure for multiple stations across the ice shelf. High-frequency ambient noise seismology presents opportunities for
continuous assessment of near surface ice shelf or other firn environments.