Comparison of decadal low-frequency ambient noise trends measured in the northern Pacific Ocean: ATOC and CTBTO systems

Trend estimates from 25 Hz to more than 50 Hz collected from 1994 to 2018 in the north Pacific Ocean are compared. The majority of trends derived from Acoustic Thermometry of Ocean Climate (ATOC) systems over nearly two decades, starting at roughly 1994, suggest a decrease in ambient noise levels of up to 1 dB/year. This is observed on both coastal and deep ocean systems. (Datasets from the remaining systems show either no change or an...