Seismic Ambient Noise in Ocean Bottom Seismometer One-year Records from Gakkel Ridge Deep in Arctic Ocean

• Main Author: Li, Shuquan
• Format: Thesis
• Language: unknown
• Published: 2022
• Subjects: Arctic; Arctic Ocean; Laptev Sea; Gakkel Ridge; laptev; Sea ice
• Online Access: https://epic.awi.de/id/eprint/56290/; https://hdl.handle.net/10013/epic.ae021f67-18ac-45cf-9496-36f12a6afad6

Ambient seismic noises exist everywhere on Earth. The interaction of ocean waves generates microseism noise in the 2-20 s period band. Strong sea ice prevents large ocean waves from forming, but sea ice can also be broken into small floes by bigger waves due to the increased fetch, which occurs usually in autumn. I quantify and analyze one-year seismic noise observations from a network of four ocean bottom seismometers underneath the arctic sea ice in the Gakkel Ridge Deep, and I use the modeled wave and wind data and sea ice concentration from satellite for correlation to characterize ambient seismic noise sources and to understand how climate factors impact variability of microseismic power. A high-frequency (3-60 Hz) noise that only occurs in the presence of sea ice and is most likely connected to wind speed and direction, suggested sea ice movements on a local scale. Reduced sea ice and increased wave regional activity result in dramatically increasing short-period secondary microseism power levels during summer and autumn in a greater area up to a thousand kilometers from the seismic network or in the Laptev Sea. Storms in the marginal ice zone in October are associated with a noticeable rise in the amplitude of noises at several frequencies. The link between the atmosphere, sea ice, and ocean wave climate in the Arctic Ocean is extensively revealed in this thesis using the recording of the first deep water OBS in the Arctic Ocean.