Iceberg calving is a natural process, occurring when a rift opens in the edge of a glacier, caused by wind or water erosion, melting ice, or other events, resulting in an iceberg breaking away and falling into the ocean. The rate at which icebergs calve from glaciers increases with increased air and water temperatures. Polar [...]

Illustration of a seismic survey with two ships, one with the sound source and the other with an array of hydrophones. Image Credit: DOSITS. At the bottom of the ocean, there are layers of sediments that contain information about the Earth’s history and below the sediment are layers of the ocean crust.  Seismic [...]

Background One of the ocean’s response to global climate change is a rise in average water temperature. Where in the ocean the warming occurs and the rate at which it occurs are of great interest to climatologists. Measuring ocean temperature to monitor and understand changes due to climate change presents some challenges because: • The [...]

Updated October 16, 2020 Introduction The novel coronavirus (COVID-19) has had a major impact on society around the globe. Shelter-in-place orders and non-essential travel bans have had significant effects at all levels, from local to national economies. There have been unexpected, wide-ranging, trickle-down effects from these changes, including shifts in local and regional underwater noise [...]

Decadal Decreases in the Frequency (Pitch) of Baleen Whale Vocalizations Blue whales are the largest living mammal species. Their long, slender bodies can reach lengths of 30.5 m (100 ft) and weigh up to 160 tons. Blue whales produce stereotyped calls, described as pulses, grunts, groans, and moans, which are typically in the 15-40 [...]

Earthquakes and other geologic events produce acoustic signals that can be measured and monitored on land and underwater. Seismic energy from submarine earthquakes is converted into acoustic energy at the seafloor-water boundary.  A Tertiary wave (or T-wave) is an acoustic signal associated with earthquakes. T-waves propagate efficiently in the ocean compared to seismic waves through [...]

Measuring and mitigating the potential impacts of vessel noise on endangered killer whales Underwater sound associated with commercial vessel traffic is one, recognized threat to the southern resident population of killer whales. Image credit: NOAA, NWFSC. Southern resident killer whales (SRKW) are an endangered marine mammal population found off the Pacific coasts of [...]

An engineer prepares to deploy a single airgun. The airgun will be suspended about 8 m below the water surface from the white float seen at the bottom of the image. Image courtesy of the National Science Foundation. An airgun is a tool used to examine layers of the seafloor and study the Earth’s [...]

Using Underwater Acoustics to Detect and Measure Global Ocean Methane Flux Close up imagery of methane hydrate. Scientists study methane hydrates as a potential natural gas source and for its potential role in releasing methane to the atmosphere during climate change events. Image courtesy of the NOAA Office of Ocean Exploration and Research. [...]

Hydrophone Provides Continuous, Live Stream of Deep Sea Sounds from Monterey Bay Location of the MARS hydrophone, on the Smooth Ridge, at the edge of Monterey Canyon, approximately 30 km (18 mi) from shore. Image credit: MBARI. The Monterey Accelerated Research System (MARS) cabled observatory, the first cabled oceanographic observatory on the U.S. [...]