Science Icebreaker Activities: An Example from Gravitational Wave Astronomy

At the beginning of a class or meeting an icebreaker activity is often used to help loosen the group and get everyone talking. Our motivation is to develop activities that serve the purpose of an icebreaker, but are designed to enhance and supplement a science-oriented agenda. The subject of this article is an icebreaker activity related to gravitational wave astronomy. We first describe the unique gravitational wave signals from three distinct sources: monochromatic binaries, merging compact objects, and extreme mass ratio encounters. These signals form the basis of the activity where participants work to match an ideal gravitational wave signal with noisy detector output for each type of source.Comment: Accepted to The Physics Teacher. Original manuscript divided into two papers at the request of the referee. For a related paper on gravitational wave observatories see physics/050920

Underwater Noise from Arctic Shipping: Impacts, Regulations and Recommendations

Marine mammals, including whales, walrus, and seals, rely heavily on sounds for survival. The Arctic soundscape has long been shaped by their clicks and calls. The rapid loss of summer sea ice that's been observed in recent years is opening this once largely inaccessible region to ship traffic. The low-frequency sounds that ships generate propagate efficiently and travel vast distances in deep water marine environments. This means that the Arctic is becoming noisier, which could have a profound impact on marine mammals

The International Bathymetric Chart of the Arctic Ocean (IBCAO) Version 3.0

[1] The International Bathymetric Chart of the Arctic Ocean (IBCAO) released its first gridded bathymetric compilation in 1999. The IBCAO bathymetric portrayals have since supported a wide range of Arctic science activities, for example, by providing constraint for ocean circulation models and the means to define and formulate hypotheses about the geologic origin of Arctic undersea features. IBCAO Version 3.0 represents the largest improvement since 1999 taking advantage of new data sets collected by the circum-Arctic nations, opportunistic data collected from fishing vessels, data acquired from US Navy submarines and from research ships of various nations. Built using an improved gridding algorithm, this new grid is on a 500 meter spacing, revealing much greater details of the Arctic seafloor than IBCAO Version 1.0 (2.5 km) and Version 2.0 (2.0 km). The area covered by multibeam surveys has increased from ∼6% in Version 2.0 to ∼11% in Version 3.0

VHF downline communication system for SLAR data

A real time VHF downlink communication system is described for transmitting side-looking airborne radar (SLAR) data directly from an aircraft to a portable ground/shipboard receiving station. Use of this receiving station aboard the U.S. Coast Guard icebreaker Mackinaw for generating real-time photographic quality radar images is discussed. The system was developed and demonstrated in conjunction with the U.S Coast Guard and NOAA National Weather Service as part of the Project Icewarn all weather ice information system for the Great Lakes Winter Navigation Program

Expedition 302 geophysics: integrating past data with new results

In preparation for IODP Expedition 302, Arctic Coring Expedition (ACEX), a site survey database comprising geophysical and geological data from the Lomonosov Ridge was compiled. The accumulated database includes data collected from ice islands, icebreakers, and submarines from 1961 to 2001. In addition, seismic reflection profiles were collected during Expedition 302 that complement the existing seismic reflection data and facilitate integration between the acoustic stratigraphy and the Expedition 302 drill cores. An overview of these data is presented in this chapter.It is well recognized that collecting geophysical data in ice-covered seas, in particular the Arctic Ocean, is a challenging endeavor. This is because much of the Arctic Ocean is continuously covered with ice thicknesses that vary from 1 to 6 m. Over the continental shelves, sea ice can be absent during summer months, but it is present year-round in the central basins. This ice cover is the most dominant feature of the Arctic Ocean environment. It circulates in the ocean basin in two main circulation patterns: the Transpolar Drift and the Beaufort Gyre (see the "Expedition 302 summary" chapter; Rudels et al., 1996).Expedition 302 sites are located within the less severe of these two ice circulation systems, the Transpolar Drift, which primarily moves sea ice from the shelves where it is formed (the Laptev and East Siberian Seas) across the basin and exits through the Fram Strait. During late summer, concentrations of Arctic sea ice can be <100% (10/10 ice cover), making it possible for icebreakers to operate. Average ice concentrations in the central Arctic Ocean during summer months can locally vary from partially open water (6/10) to completely ice covered (10/10). This sea-ice cover can move at speeds up to 0.5 kt.Early Arctic Ocean geophysical exploration was performed from ice-drift stations (Weber and Roots, 1990). However, the tracks from these drifting ice stations were controlled "by the whims of nature" (Jackson et al., 1990), preventing detailed, systematic surveys of predetermined target areas. These ice-drift stations were set up on stable icebergs that were trapped in sea ice and moved generally with the large drift patterns, but locally they were erratic, so preselected locations could not be surveyed. In the late 1980s, single icebreakers began to be used for oceanographic survey work in the Arctic Ocean. Between 1991 and 2001, four scientific icebreaker expeditions to the Lomonosov Ridge took place. These cruises all experienced local sea-ice conditions varying between 8/10 and 10/10. During these expeditions, towed geophysical equipment was occasionally damaged or lost, either because of a rapidly closing wake caused by local ice pressure or because ice had cut the air gun array.Conventionally powered icebreakers reached as far as the North Pole for the first time during the 1991 Expedition (Andersen and Carlsonn, 1992; Fütterer, 1992). Geophysical results from this expedition collected two important reflection profiles, AWI-91090 and AWI-91091, that crossed the Lomonosov Ridge between 87° and 88°N. These profiles imaged a ~450 m thick, well-stratified and apparently undisturbed drape of sediments overlying a prominent acoustic unconformity (Jokat et al., 1992) that spawned the idea to conduct a paleoceanographic drilling expedition to this Ridge.The use of US Navy nuclear submarines for geophysical mapping was implemented through the Science Ice Exercise program (SCICEX) (Newton, 2000). The development of the Seafloor Characterization and Mapping Pods (SCAMP), which hold a Chirp subbottom profiler, swath bathymetric profiler, and side scan sonar, was an essential part of the SCICEX program (Chayes et al., 1996). In 1999, the Lomonosov Ridge geophysical database was augmented with acoustic data acquired during the SCICEX program using the SCAMP system mounted on the US nuclear submarine USS Hawkbill (Edwards and Coakley, 2003)

Towards a better use of arctic marine infrastructure: EU-PolarNet, EUROFLEETS2 and ARICE

The Polar Regions may seem remote, but the observed rapid changes now affecting both the Arctic and Antarctic regions have resulted in significant consequences for the weather and climate in lower latitudes, including Europe. Environmental changes being observed, particularly in the Arctic, are a clear indication of the impending shifts that will increasingly affect European environment, society and industry. Changes in the Polar Regions present societal challenges, but also economic opportunities for Europe and the world. Science is a vital tool in understanding what is driving the rapid changes being observed at high latitudes. Research is also necessary to make our climate models and forecasting more realistic by identifying and reducing important sources of uncertainty that may impair reliable prediction. However the scale of many of the questions being posed is now recognised as being beyond the capabilities of individual nations and strong international cooperation is needed to overcome these challenges. There is often a need to obtain data from geographically widely separated areas of the Polar Regions and these need complementary observational schemes to be implemented for valid inter-comparisons. Similarly the costs of operating infrastructure in Polar Regions are becoming increasingly challenging and there is a need therefore to cooperate on infrastructure access and shared costs to optimise the support of larger research programmes. The presentation will introduce three European projects: EU-PolarNet, EUROFLEETS2 and ARICE which actively work on improving infrastructure development and access in the Polar Regions in cooperation with international partners. The examples given are from the Arctic Ocean but similar models of transnational access and infrastructure sharing will apply for the Antarctic.Peer Reviewe

Underwater radiated noise levels of a research icebreaker in the central Arctic Ocean

U.S. Coast Guard Cutter Healy\u27s underwater radiated noise signature was characterized in the central Arctic Ocean during different types of ice-breaking operations. Propulsion modes included transit in variable ice cover, breaking heavy ice with backing-and-ramming maneuvers, and dynamic positioning with the bow thruster in operation. Compared to open-water transit, Healy\u27s noise signature increased approximately 10 dB between 20 Hz and 2 kHz when breaking ice. The highest noise levels resulted while the ship was engaged in backing-and-ramming maneuvers, owing to cavitation when operating the propellers astern or in opposing directions. In frequency bands centered near 10, 50, and 100 Hz, source levels reached 190–200 dB re: 1 μPa at 1 m (full octave band) during ice-breaking operations