US Coast Guard Cutter Research Articles

Arctic Freshwater Sources and Ocean Mixing Relationships Revealed With Seawater Isotopic Tracing

AbstractThe Arctic Ocean and adjacent seas are undergoing increased freshwater influx due to enhanced glacial and sea ice melt, precipitation, and runoff. Accurate delineation of these freshwater sources is vital as they critically modulate ocean composition and circulation with widespread and varied impacts. Despite this, the delineation of freshwater sources using physical oceanographic measurements (e.g., temperature, salinity) alone is challenging and there is a requirement to improve the partitioning of ocean water masses and their mixing relationships. Here, we complement traditional oceanographic measurements with continuous surface seawater isotopic analysis (δ18O and deuterium excess) across a transect extending from coastal Alaska to Baffin Bay and the Labrador Sea conducted from the US Coast Guard Cutter Healy in Autumn 2021. We find that the diverse isotopic signatures of Arctic freshwater sources, coupled with the high freshwater proportion in these marine systems, facilitates detailed fingerprinting and partitioning. We observe the highest freshwater composition in the Beaufort Sea and Amundsen Gulf regions, with heightened freshwater content in eastern Baffin Bay adjacent to West Greenland. We apply isotopic analysis to delineate freshwater sources, revealing that in the Western Arctic freshwater inputs are dominated by meteoric water inputs—specifically the Mackenzie River—with a smaller sea ice meltwater component and in Baffin Bay the primary sources are local precipitation and glacial meltwater discharge. We demonstrate that such freshwater partitioning cannot be achieved using temperature‐salinity relationships alone, and highlight the potential of seawater isotopic tracers to assess the roles and importance of these evolving freshwater sources.

Nonintrusive Ventilation System Diagnostics

Ventilation systems depend on periodic preventive maintenance. Unfortunately, mission critical systems, exposed to varying levels of particulates and other contaminants, may require unpredictable and highly variable maintenance intervals. Direct sensing for pressure drops or other condition metrics can provide prognostic indicators, but at the expense of the installation and maintenance burden of the sensors themselves. Rotor slot harmonics from motors have been observed for decades to track motor speed. This paper presents hardware instrumentation and a signal processing algorithm that can nonintrusively track the rotor slot harmonics of multiple fan motors in an aggregate electrical stream. Combined with a physics-based model of the motors under observation, this nonintrusive data can be used to track the maintenance condition of multiple fan motors on a single electrical service, minimizing the costs of installation and data analysis and reducing the total number of sensors necessary to track fan health. Results are demonstrated with experiments on-board a US Coast Guard Cutter.

Testing and Evaluating Low Altitude Unmanned Aircraft System Technology for Maritime Domain Awareness and Oil Spill Response in the Arctic

AbstractNational and international policies and treaties require the protection and exploration of the Arctic. The maritime services play a primary role in pursuing responsible Arctic stewardship by protecting the environment and the personnel conducting operations and research in this harsh environment. The National Oceanic and Atmospheric Administration (NOAA) is an important partner to the U.S. Coast Guard (USCG) in hazard response and mitigation (including oil spills and search and rescue). During Arctic Shield exercises, as part of the USCG Research and Development Center's Arctic Technology Evaluation, manned and unmanned systems including the AeroVironment Puma™ All Environment (AE) (Puma) Unmanned Aircraft System (UAS), were used to provide real-time information for maritime domain awareness and oil spill response in the Arctic. Real-time information distribution and maritime domain awareness are critical to prepare for and respond to potential environmental disasters in the Arctic. Additionally, the Puma was assessed for shipboard operations capabilities, Arctic air space coordination, deconfliction and safety issues, and real-time data visualization through the Arctic Environmental Response Management Application® as part of a larger data management plan. The results are provided from the successful Puma testing during the Arctic Shield 2013 and 2014 exercises aboard the USCG Cutter (USCGC; Icebreaker) Healy. An overview of these operations is given with recommendations for future testing and technology assessments of small UAS platforms for Arctic shipboard operational deployments. These findings are put into context for utilization in the field to support operations and decision making in the case of a real oil spill in the Arctic region.

Spatial variation in shallow sediment methane sources and cycling on the Alaskan Beaufort Sea Shelf/Slope

The MITAS (Methane in the Arctic Shelf/Slope) expedition was conducted during September, 2009 onboard the U.S. Coast Guard Cutter (USCGC) Polar Sea (WAGB-11), on the Alaskan Shelf/Slope of the Beaufort Sea. Expedition goals were to investigate spatial variations in methane source(s), vertical methane flux in shallow sediments (<10 mbsf), and methane contributions to shallow sediment carbon cycling. Three nearshore to offshore transects were conducted across the slope at locations approximately 200 km apart in water column depths from 20 to 2100 m. Shallow sediments were collected by piston cores and vibracores and samples were analyzed for sediment headspace methane (CH4), porewater sulfate (SO42−), chloride (Cl−), and dissolved inorganic carbon (DIC) concentrations, and CH4 and DIC stable carbon isotope ratios (δ13C). Downward SO42− diffusion rates estimated from sediment porewater SO42− profiles were between −15.4 and −154.8 mmol m−2 a−1 and imply a large spatial variation in vertical CH4 flux between transects in the study region. Lowest inferred CH4 fluxes were estimated along the easternmost transect. Higher inferred CH4 flux rates were observed in the western transects. Sediment headspace δ13CCH4 values ranged from −138 to −48‰, suggesting strong differences in shallow sediment CH4 cycling within and among sample locations. Measured porewater DIC concentrations ranged from 2.53 mM to 79.39 mM with δ13CDIC values ranging from −36.4‰ to 5.1‰. Higher down-core DIC concentrations were observed to occur with lower δ13C where an increase in δ13CCH4 was measured, indicating locations with active anaerobic oxidation of methane. Shallow core CH4 production was inferred at the two western most transects (i.e. Thetis Island and Halkett) through observations of low δ13CCH4 coupled with elevated DIC concentrations. At the easternmost Hammerhead transect and offshore locations, δ13CCH4 and DIC concentrations were not coupled suggesting less rapid methane cycling. Results from the MITAS expedition represent one of the most comprehensive studies of methane source(s) and vertical methane flux in shallow sediments of the U.S. Alaskan Beaufort Shelf to date and show geospatially variable sediment methane flux that is highly influenced by the local geophysical environment.

Collecting winter data on U.S. Coast Guard icebreakers

Winter research and monitoring of icebound rivers, lakes, and coastal seas to date has usually involved seagoing civilian scientists leading survey efforts. However, because of poor weather conditions and a lack of safe research platforms, scientists collecting data during winter face some difficult and often insurmountable problems. To solve these problems and to further research and environmental monitoring goals, new partnerships can be formed through integrating efforts of the U.S. Coast Guard (USCG) with citizen science initiatives. USCG and a research group at Ohio's Bowling Green State University are entering the third year of such a partnership, in which icebreaking operations in Lake Erie using USCG Cutter Neah Bay support volunteer data collection. With two additional USCG vessels joining the program this winter season, the partnership serves as a timely and useful model for worldwide environmental research and monitoring through citizen science and government collaboration.

Improvement of Propeller Hydrodynamic Drag and Efficiency on USCG Cutters Operating in Trailshaft Mode

AbstractLarge US Coast Guard cutters spend much of their underway time with only one of two propellers operating. The offline propeller is “trailed,” often creating a significant amount of hydrodynamic drag. Operators from the fleet do not appear to have any specific guidance on how best to reduce this drag. Using the propeller analysis tools PSF‐3 and PSF‐10, propeller thrust coefficient values versus advance coefficient values were created for the propellers of the USCG 270′ cutters. These values—and the associated drag—vary significantly in magnitude based on the trailed propeller pitch. Based upon sea trial measurements, expected magnitudes of this drag versus pitch setting were predicted. Minimum drag pitch settings were identified for an operational 270′ cutter at 8 knots. RPM and pitch settings for maximum hydrodynamic efficiency for the online shaft are sometimes developed during ship acquisition. In the current work, a methodology for conducting such a study is discussed to demonstrate to ship operators the relative ease with which they could perform this analysis on board, if effective power and propeller thrust coefficient values are available. Consideration of prime mover specific fuel consumption rates together with propeller hydrodynamic efficiencies is discussed.

Icebreaker expedition collects key Arctic seafloor and ice data

The recently completed Healy‐Oden Trans‐Arctic Expedition 2005 (HOTRAX′05) retrieved 29 piston cores averaging nearly 12 meters in length from a complete transect across the central Arctic Ocean (Figure 1). These cores provide a critically‐needed sample cache for both a pan‐Arctic stratigraphy and a long‐awaited paleoclimate record that it is hoped will greatly improve the understanding of how deepwater is exchanged between Arctic basins, how the climate system in the Arctic works over longer time intervals, and how the Arctic system interacts with global systems. The coring was done from the U.S. Coast Guard Cutter (USCGC) Healy, while oceanographic measurements were made from the Swedish icebreaker Oden.In addition to coring and oceanography, HOTRAX mapped the seafloor with multibeam bathymetry and collected chirp sonar profiles that not only mapped the strata to a sub‐bottom depth of 50–100 meters, but also provided detailed information on the geologic context of the core sites.

Crystalline structure and physical properties of ship superstructure spray ice

In February and March 1990 the US Army Corps of Engineers Cold Regions Research and Engineering Laboratory (CRREL) made measurements of superstructure ice on a US Coast Guard cutter in the Bering Sea. Twenty–three ice samples were removed from bulkheads, decks and icicles during two icing events. Ice crystal measurements included crystal size, shape, orientation, brine–pocket location, size and shape, internal layering, and air–bubble sizes. Ice property measurements included salinity, density and temperature, with computed estimates of air and brine volume. This paper describes crystal and physical properties of the accreted ice and their relationship to ice sample position on the ship. Texturally, accreted ice resembled frazil ice that forms from the consolidation of freely nucleated ice crystals in sea water. This resemblance is also reflected in bulk salinities, ranging from 24‰ to 7‰, compared with frazil formed during the initial stages of freezing of sea water, where bulk salinities can exceed 10‰. Crystalline structures of accreted ice ranged from rounded to polygonal. Generally, rounded crystals would be expected for ice formed from sea–spray droplets, polygonal crystals may be attributed to thermally driven modification. No trend towards reorientation of crystallographic c–axes in either freshly accreted or thermally modified ice was observed. Mean crystal sizes ranged from 0.56 mm to 1.15 mm, with even larger crystals in icicles. Ice salinity averaged ca .12‰ on bulkheads and ca .21‰ on decks. Ice densities ranged from 0.69 to 0.92 Mg m −3 and were generally higher on decks. Bulkhead ice had larger computed total porosity and air volume and lower brine volume than deck ice. Samples taken from decks and bulkheads generally compared well with Russian and Japanese measurements.

Pharmacy Officer Support of U.S. Coast Guard Cutters

U.S. Public Health Service commissioned officers serve in 16 pharmacy billets with the U.S. Coast Guard (USCG). Thirteen of these billets involve serving as points of contact for, and providing logistical, materiel, and educational support to, USCG cutters. USCG instructions have solidified the role of pharmacy officers in the support of USCG afloat units. This article describes one USCG pharmacy officer's experience in providing pharmacy service support to USCG cutters based in Alameda, California, Yerba Buena Island (San Francisco), California, and Honolulu, Hawaii.

Hailing and boarding: the psychological impact of US coast guard boardings

Measures the impact of armed US Coast Guard boardings on those aboard boarded vessels. A sample of fifty subjects (half members of a graduate class on “Maritime Crime and its Prevention”, half others), completed questionnaires after experiencing a (pre‐arranged but undisclosed) interception and boarding by a US Coast Guard Cutter of the vessel on which they were traveling. Subjects reported satisfaction with the conduct of the boarding, but experienced different anxiety levels during the encounter, ranging from low levels (one third), medium levels (one third) to relatively high levels of anxiety. Boarding parties should be concerned with the latter group. Training and sensitivity to deal with that group needs to be emphasized.

An intelligent system for US Coast Guard cutter scheduling

A software system developed for the United States Coast Guard for producing a day to day schedule for a fleet of ships over a one year period is presented. The development process from knowledge elicitation through model building to the analysis of computational performance is addressed and the position of scheduling within a taxonomy of decision problems is discussed with reference to appropriate methodology. A schedule generator and a discrete optimisation model lie at the heart of the system and a diagnostic analyzer is incorporated to deal with various subjective and objective issues. The design philosophy and the integration in a database information support system is discussed. In addition to its tactical uses the system is increasingly used as a strategic investigative tool.