Christian Meinig

The NTHMP Tsunameter Network

A tsunameter (soo-NAHM-etter) network has been established in the Pacific by the National Oceanic and Atmospheric Administration. Named by analogy with seismometers, the NOAA tsunameters provide early detection and real-time measurements of deep-ocean tsunamis as they propagate toward coastal communities, enabling the rapid assessment of their destructive potential. Development and maintenance of this network supports a State-driven, high-priority goal of the U.S. National Tsunami Hazard Mitigation Program to improve the speed and reliability of tsunami warnings. The network is now operational, with excellent reliability and data quality, and has proven its worth to warning center decision-makers during potentially tsunamigenic earthquake events; the data have helped avoid issuance of a tsunami warning or have led to cancellation of a tsunami warning, thus averting potentially costly and hazardous evacuations. Optimizing the operational value of the network requires implementation of real-time tsunami forecasting capabilities that integrate tsunameter data with numerical modeling technology. Expansion to a global tsunameter network is needed to accelerate advances in tsunami research and hazard mitigation, and will require a cooperative and coordinated international effort.

Evidence for deformation associated with the 1998 eruption of Axial Volcano, Juan de Fuca Ridge, from acoustic extensometer measurements

Acoustic extensometer instruments capable of making precise daily measurements of horizontal distance were deployed across the north rift zone of Axial Volcano in June 1996 and were in place when a submarine eruption began on Axials south rift zone in January 1998. The instruments recorded a gradual 9-cm extension over a 405-m baseline leading up to the eruption, and then an abrupt, 4-cm contraction at the time of the eruption. An elastic point-source deformation model shows that deflation of Axials summit can explain both the 4-cm distance decrease at the extensometer array and a 3.2-m subsidence measured by another instrument in the caldera, if the pressure source is located at a depth of 3.8 km below the center of the caldera. The 9-cm distance increase may represent pre-eruption spreading across the rift zone.

ATLAS buoy-reengineered for the next decade

The ATLAS buoy system was developed under modest auspices in the early 1980s to measure upper ocean heat content and surface meteorological parameters in support of air-sea interaction studies in the eastern equatorial Pacific. Since that time, the array has been the centerpiece of an international climate study with nearly 70 surface buoys in the TAO array spanning the Pacific from approximately 8/spl deg/N to 8/spl deg/S from longitudes 137/spl deg/E to 95/spl deg/W. The moorings and data system have proven to be robust and reliable but have changed little from the original design, which was limited by the technology available at the time. An engineering effort to improve the system with enhanced sensor capabilities and modified cable telemetry has been implemented and several prototype moorings have been successfully deployed.

Robust Sensor for Extended Autonomous Measurements of Surface Ocean Dissolved Inorganic Carbon

Ocean carbon monitoring efforts have increased dramatically in the past few decades in response to the need for better marine carbon cycle characterization. Autonomous pH and carbon dioxide (CO2) sensors capable of yearlong deployments are now commercially available; however, due to their strong covariance, this is the least desirable pair of carbonate system parameters to measure for high-quality, in situ, carbon-cycle studies. To expand the number of tools available for autonomous carbonate system observations, we have developed a robust surface ocean dissolved inorganic carbon (DIC) sensor capable of extended (>year) field deployments with a laboratory determined uncertainty of ±5 μmol kg(-1). Results from the first two field tests of this prototype sensor indicate that measurements of DIC are ∼90% more accurate than estimates of DIC calculated from contemporaneous and collocated measurements of pH and CO2. The improved accuracy from directly measuring DIC gives rise to new opportunities for quantitative, autonomous carbon-cycle studies.

Tracking beaked whales with a passive acoustic profiler float.

Acoustic methods are frequently used to monitor endangered marine mammal species. Advantages of acoustic methods over visual ones include the ability to detect submerged animals, to work at night, and to work in any weather conditions. A relatively inexpensive and easy-to-use acoustic float, the QUEphone, was developed by converting a commercially available profiler float to a mobile platform, adding acoustic capability, and installing the ERMA cetacean click detection algorithm of Klinck and Mellinger [(2011). J. Acoust. Soc. Am. 129(4), 1807-1812] running on a high-power DSP. The QUEphone was tested at detecting Blainvilles beaked whales at the Atlantic Undersea Test and Evaluation Center (AUTEC), a Navy acoustic test range in the Bahamas, in June 2010. Beaked whale were present at AUTEC, and the performance of the QUEphone was compared with the Navys Marine Mammal Monitoring on Navy Ranges (M3R) system. The field tests provided data useful to evaluate the QUEphones operational capability as a tool to detect beaked whales and report their presence in near-real time. The range tests demonstrated that the QUEphones beaked whale detections were comparable to that of M3Rs, and that the float is effective at detecting beaked whales.

The use of Saildrones to examine spring conditions in the Bering sea

New technologies can help scientists measure and understand Arctic warming, sea ice loss and ecosystem change. NOAA has worked with Saildrone, Inc., to develop an unmanned surface vehicle (USV)-Saildrone-to make ocean surface measurements autonomously, even in challenging high-latitude conditions. USVs augment traditional research ship cruises, mitigate ship risk in high seas and shallow water, and make lower cost measurements. Under remote control, USV sampling strategy can be adapted to meet changing needs. Two Saildrones conducted 97-day missions in the Bering Sea in spring-summer 2015, reliably measuring atmospheric and oceanic parameters. Measurements were validated against shipboard values. Following that, the Saildrone sampling strategies were modified, first to measure the effects of sea-ice melt on surface cooling and freshening, and then to study the Yukon River plume.

The use of Saildrones to examine spring conditions in the Bering Sea: Vehicle specification and mission performance

During recent decades the US Arctic is experiencing a rapid loss of sea ice and subsequently increasingly warmer water temperatures. To better study this economically and culturally important marine ecosystem and the changes that are occurring, the use of new technologies is being explored to supplement traditional ship, satellite and mooring based data collection techniques. Unmanned surface vehicles (USV) are a rapidly advancing technology that has the potential to meet the requirement for long duration and economical scientific data collection with the ability for real-time data and adaptive sampling. In 2015, the National Oceanic and Atmospheric Administrations Pacific Marine Environmental Laboratory (NOAA-PMEL), the University of Washington (UW) and Saildrone Inc. (Alameda, California) explored the use of a novel USV technology in the Bering Sea and Norton Sound. Two Saildrones, wind and solar powered unmanned surface vehicles that can be used for extended research missions in challenging environments, were equipped with a suite of meteorological and oceanographic sensors. During the >3 month mission, the vehicles each traveled over 4100 nm, successfully completing several scientific survey assignments. This mission demonstrated the capability of the Saildrone vehicle to be launched from a dock to conduct autonomous and adaptive oceanographic research in a harsh, high-latitude environment.

The PRAWLER, a vertical profiler powered by wave energy

We describe a new, wave-powered profiling instrument designed as one part of a low cost, easily deployed, open ocean mooring system. The PRAWLER (PRofiling crAWLER) is a small, 15 kg instrument that uses the motion from an ordinary surface buoy to traverse the upper 500 meters of mooring line by rectifying the vertical motion with a pair of cam cleats. After climbing up to a commanded depth, it free falls and obtains a continuous ocean data profile at a terminal speed of ~30 cm/s. In Pacific and Atlantic Ocean deployments we easily obtain 20 to 30 profiles per day. Two sets of opposing cam cleats permit two additional modes: fixed and climbing down. When fixed to the line, the instrument can obtain a continuous Eulerian time series identical to a discrete instrument, or can park at depth to avoid unnecessary profiles to save power and protect from bio-fouling. It is also able to climb down the wire, needed when equatorial currents pull a mooring over so far such that the drag vector overcomes the instrument net weight. These four positions of the cam cleats are controlled by an ultra-low power microcontroller and a motor that uses about 5 joules per profile. The PRAWLER is presently equipped with a Seabird pumped CTD and an Aanderaa Dissolved Oxygen Optode. PRAWLER data and commands are transmitted via an inductive modem to the surface buoy, and sent along with buoy meteorological data by Iridium/RUDICS to shore. Powered by lithium batteries the endurance with 8 profiles per day is about one year. Deployment results and engineering observations are presented.

A Real-time Acoustic Observing System (RAOS) for killer whales

A prototype real-time, passive-acoustic observing system for killer whales was developed and tested off the coast of Newport, Oregon, USA. The system consists of two modules: 1) the passive-acoustic monitoring (PAM) module, which sits on the seafloor and continuously monitors the underwater soundscape for killer whale calls, and 2) a surface buoy, which receives information on acoustics detections from the PAM module via an underwater acoustic modem link and relays the information to shore via an Iridium™ satellite connection. The system was deployed in ~65 m deep water off Oregon in September 2015 for five days, during which the real-time detection capability was tested. A high rate of false positive detections was observed. Later analysis revealed that Dolphin clicks and impulsive sounds by invertebrate caused detection errors. During the experiment, killer whale sounds were projected with an underwater playback system to validate the detection algorithm.

Deployment and recovery of a full-ocean depth mooring at Challenger Deep, Mariana Trench

We present the details of a unique deep-ocean instrument package and mooring that was deployed at Challenger Deep (10,984 m) in the Marianas Trench. The mooring is 45 m in length and consists of a hydrophone, RBRTM pressure and temperature loggers, nine Vitrovex® glass spheres and a mast with a satellite beacon for recovery. The mooring was deployed in January and recovered in March 2015 using the USCG Cutter Sequoia. The pressure logger recorded a maximum pressure of 10,956.8 decibars, for a depth of 10,646.1 m. To our knowledge, this is only the fourth in situ measurement of depth ever made at Challenger Deep. The hydrophone recorded for ~1 hour and stopped shortly after descending to a depth of 1,785 m (temperature of 2.4°C). The record at this depth is dominated by the sound of the Sequoias engines and propellers.