Observations of the seasonality of the Antarctic microseismic signal, and its association to sea ice variability

Mélanie Grob (1) , Alessia Maggi (2) , Eléonore Stutzmann (3)

1 IPGS-GE - Géophysique expérimentale (IPGS)
2 IPGS-Sismologie - Sismologie (IPGS)
3 IPGP - Institut de Physique du Globe de Paris

Seismic noise spectra at all seismic stations display two peaks in the 1-20 s period band, called primary and secondary microseisms. They are caused by the coupling of ocean waves into Rayleigh waves. At most locations, microseismic power is greater during local winter (when nearby oceans are stormier) than local summer. This tendency is reversed for stations in Antarctica, where growth of local winter sea ice seems to impede microseism generation in near coastal areas. A decade of continuous data from coastal seismic stations in Antarctica show systematic seasonality in microseismic signal levels, and demonstrate associations with both broad‐ scale and local sea‐ice conditions. Primary microseisms are known to be generated at the coast and the modulation that we observe can be associated with sea‐ice variations both in the vicinity of the station and along other Antarctic coasts. The similar modulation of short‐period secondary microseisms corroborates their mostly near‐coastal origin, while the con- tinued presence of long‐period secondary microseisms sug- gests more distant source regions. These observations could be used to extend the monitoring of climate variability prior to the availability of satellite‐derived climate indicators.

Domaines: Géophysique [physics.geo-ph]; Géophysique [physics.geo-ph]; Milieux et Changements globaux

Mélanie Grob, Alessia Maggi, Eléonore Stutzmann. Observations of the seasonality of the Antarctic microseismic signal, and its association to sea ice variability. Geophysical Research Letters, 2011, 38, pp.L11302. ⟨10.1029/2011GL047525⟩. ⟨hal-00679388⟩