Unusually loud ambient noise in tidewater glacier fjords: A signal of ice melt

作者：Pettit Erin Christine; Lee Kevin Michael; Brann Joel Palmer; Nystuen Jeffrey Aaron; Wilson Preston Scot; O' Neel Shad

来源：Geophysical Research Letters, 2015, 42(7): 2309-2316.

DOI：10.1002/2014GL062950

• ice-ocean interactions
• fjord circulation
• tidewater glaciers
• passive acoustics
• marine mammal behavior
• glacier change

In glacierized fjords, the ice-ocean boundary is a physically and biologically dynamic environment that is sensitive to both glacier flow and ocean circulation. Ocean ambient noise offers insight into processes and change at the ice-ocean boundary. Here we characterize fjord ambient noise and show that the average noise levels are louder than nearly all measured natural oceanic environments (significantly louder than sea ice and nonglacierized fjords). Icy Bay, Alaska, has an annual average sound pressure level of 120dB (referenced to 1Pa) with a broad peak between 1000 and 3000Hz. Bubble formation in the water column as glacier ice melts is the noise source, with variability driven by fjord circulation patterns. Measurements from two additional fjords, in Alaska and Antarctica, support that this unusually loud ambient noise in Icy Bay is representative of glacierized fjords. These high noise levels likely alter the behavior of marine mammals.

• 出版日期2015-4-16