Scientists at the Naval Research Laboratory - Stennis Space Center (NRL-SSC) measured a record-size ocean wave when the eye of Hurricane Ivan passed over NRL moorings deployed last May in the Gulf of Mexico. The possibility of a super wave is often suggested by anecdotal evidence such as damage caused by Hurricane Ivan in September of 2004 to an offshore rig in the Gulf of Mexico that was nearly 80 feet above the ocean surface. Hence, some of the destruction done by Ivan has been attributed to a rogue wave. According to industry and national weather sources, the damage done by waves during Ivan has been on the extreme high end for a category 4 hurricane. Ivan has been the most expensive hurricane ever for the oil and gas industry in the Gulf. The Minerals Management Service (MMS) reported that Ivan amazingly forced evacuation of 75% of the manned platforms in the Gulf (574 platforms) and 59% of the drilling rigs (69 rigs), set adrift 5 rigs and sunk 7 rigs entirely. However, the damage by Hurricane Ivan in the oil fields in the Gulf cannot be measured by how many platforms or rigs were destroyed. The most costly damage is believed to have been made to the underwater pipelines. Aside from obvious leaks, some pipelines were reported to have moved 3000 ft while others were buried under 30 feet of mud and cannot be found. The most extensive damage to the pipelines is attributed to undersea mudslides (equivalent to a snow avalanche) and to extreme waves. The complete findings of this study are published in the August 5, 2005 issue of Science.
During NRL’s Slope to Shelf Energetics and Exchange Dynamics (SEED) field experiment, six current profiler moorings that also contained wave/tide gauges (Sea-Bird Electronics SBE 26) were deployed on the continental shelf at water depths ranging between 60 and 90 meters just west of the DeSoto Canyon, about 100 miles south of Mobile Bay, Alabama. An additional eight deep moorings were deployed down the shelf slope but did not contain wave/tide gauges. Fortuitously, between 8:00 pm CDST and midnight on September 15, the eye of Ivan passed through the center of the array, and almost directly over moorings 2, 5, 8, and 11. Historically, instruments in the ocean do not even survive near misses of such powerful storms, much less direct hits. Fortunately, all of the SEED moorings survived this powerful storm, and provided the best ocean measurements of currents and waves ever obtained directly under a major hurricane.
During the approach of Ivan, a moored buoy (ID 42040), deployed by the National Data Buoy Center (NDBC) near the west side of the SEED array, registered a significant wave height of 16.0 meters (53 ft). Unfortunately, the NDBC buoy broke loose and was set adrift on September 15 at 5:00 pm CDST, just before the arrival of the main force of the hurricane. According to a spokesman at NDBC, this wave height appears to be the largest ever reported by NDBC from a hurricane and comes within a few tenths of a meter of NDBC’s all-time record reported in the North Pacific. Note that the wave heights reported by the NDBC buoys are derived from wave spectra. Buoy measurements do not report time series of surface wave elevations, and hence, maximum individual wave heights can only be statistically postulated from spectrum-derived significant wave heights. The SEED wave/tide gauges, however, provided direct time series measurements of surface wave elevations. The maximum individual crest-to-trough wave heights can be reliably obtained. At mooring 3, located under the most intense winds, the maximum measured wave height was 27.7 meters (91 feet) which was part of a group of large waves with periods of approximately 10 seconds where several waves reached heights of about 20 meters (66 feet). These waves recorded by the NRL SEED gauges are by far the largest waves ever directly measured. Even larger waves could have been missed entirely on the shelf since the surface wave data from the SEED gauges were not closely sampled in time, but were instead sampled at 1 hertz over a 512 second data burst only every 8 hours. Analysis of the wave data with the winds suggests that the wave heights likely exceeded 130 feet near the eye wall of the hurricane. Orbital wave velocities generated by such large waves during Hurricane Ivan (not rogue waves) exceeded 2 meters/second at the ocean bottom (in addition to lower-frequency measured currents that exceeded 1 meter/second) and could certainly have caused much damage to underwater structures and pipelines. The measurement of "super waves" cannot be planned and are indeed very rare. These in-situ measurements made by NRL directly under a category 4 hurricane are very valuable since they can be used to provide an assessment of potential impacts to offshore structures and operations by energetic storm waves.
Donna McKinney | EurekAlert!
A promising target in the quest for a 1-million-year-old Antarctic ice core
24.05.2018 | University of Washington
Tropical Peat Swamps: Restoration of Endangered Carbon Reservoirs
24.05.2018 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)
The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.
Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
25.05.2018 | Event News
02.05.2018 | Event News
13.04.2018 | Event News
25.05.2018 | Event News
25.05.2018 | Machine Engineering
25.05.2018 | Life Sciences