2010 Chile earthquake - NOAA buoy 34142 - water column height short

Deep-ocean Assessment and Reporting of Tsunamis (DART) is a component of an enhanced

tsunami warning system A tsunami warning system (TWS) is used to detect tsunamis in advance and issue the warnings to prevent loss of life and damage to property. It is made up of two equally important components: a network of sensors to detect tsunamis and a communica ...

. By logging changes in seafloor temperature and pressure, and transmitting the data via a surface buoy to a ground station by satellite, DART enables instant, accurate tsunami forecasts. In Standard Mode, the system logs the data at 15-minute intervals, and in Event Mode, every 15 seconds. A 2-way communication system allows the ground station to switch DART into Event Mode whenever detailed reports are needed.

Stations

Each DART station consists of a surface

buoy A buoy () is a floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with ocean currents. Types Navigational buoys * Race course marker buoys are used for buoy racing, the most prevalent form of yac ...

and a

seafloor The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth an ...

bottom pressure recording (BPR) package that detects water

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...

changes caused by

tsunamis A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater expl ...

. The surface buoy receives transmitted information from the BPR via an acoustic link and then transmits data to a satellite, which retransmits the data to ground stations for immediate dissemination to NOAA's Tsunami Warning Centers, NOAA's National Data Buoy Center, and NOAA's

Pacific Marine Environmental Laboratory The Pacific Marine Environmental Laboratory (PMEL) is a federal laboratory in the National Oceanic and Atmospheric Administration (NOAA) Office of Oceanic and Atmospheric Research (OAR). It is one of seven NOAA Research Laboratories (RLs). The PM ...

(PMEL). The

Iridium Iridium is a chemical element with the symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, it is considered the second-densest naturally occurring metal (after osmium) with a density of ...

commercial satellite phone network is used for communication with 31 of the buoys. When on-board software identifies a possible tsunami, the station leaves standard mode and begins transmitting in event mode. In standard mode, the station reports water temperature and pressure (which are converted to sea-surface height, not unlike a

depth gauge A depth gauge is an instrument for measuring depth below a reference surface. They include depth gauges for underwater diving and similar applications, and engineering instruments used to measure the depth of holes and indentations from a refer ...

or a pressure

tide gauge A tide gauge is a device for measuring the change in sea level relative to a vertical datum. It its also known as mareograph, marigraph, sea-level recorder and limnimeter. When applied to freshwater continental water bodies, the instrument may ...

) every At the start of event mode, the buoy reports measurements every for several minutes, followed by 1-minute averages for The first-generation DART I stations had one-way communication ability, and relied solely on the software's ability to detect a tsunami to trigger event mode and rapid data transmission. In order to avoid false positives, the detection threshold was set relatively high, presenting the possibility that a tsunami with a low amplitude could fail to trigger the station. The second-generation DART II is equipped for two-way communication, allowing tsunami forecasters to place the station in event mode in anticipation of a tsunami's arrival. Deep-ocean Assessment and Reporting of Tsunamis is officially abbreviated and trademarked as DART.

Background

National Oceanic and Atmospheric Administration’s

NOAA The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...

have placed Deep-ocean Assessment and Reporting of Tsunami stations in particular areas, areas with a history of generating large tsunamis, to be completely positive that the detection of tsunamis are to be as fast as possible. The year of 2001 was the completion of the first six tsunami detection buoys placed along the northern Pacific Ocean coast. In 2005 the United States president George W. Bush announced a two-year, $3.5 million, plan to install tsunami detecting buoys in the Atlantic and the Caribbean ocean in order to expand the nation’s capabilities to detect tsunamis. With the Pacific Ocean creating 85 percent of the world’s tsunamis(January 15, 2005 Saturday). Tsunami Detection To Expand; More Protection for U.S. Coastal Areas. The Washington Post, Retrieved from www.lexisnexis.com/hottopics/lnacademic , the majority of new tsunami detecting buoy equipment will be installed around the

pacific rim The Pacific Rim comprises the lands around the rim of the Pacific Ocean. The ''Pacific Basin'' includes the Pacific Rim and the islands in the Pacific Ocean. The Pacific Rim roughly overlaps with the geologic Pacific Ring of Fire. List of co ...

, while only seven buoys will be placed along the Atlantic and Caribbean coast because even though tsunamis are rare in the Atlantic, there have been records of deadly tsunamis being reported in the Atlantic. Roughly $13.8 million of the governments funding was used to procure and install exactly 32 pressure

sensor A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...

s on the ocean bottom to detect tsunamis and collect data such as the height and speed of the approaching tsunami. This proposed system, stated by the John H. Marburger the White House’s Office of Science and Technology Policy, should provide the United States’ Tsunami Warning Centers with nearly one hundred percent coverage for any approaching tsunamis as well as decline all false alarms to just about zero. During all these improvements and upgrades of the current system, roughly three fourths of the tsunami warnings were discovered to be unnecessary and a waste of money. A few years later in 2008 there are now roughly 40 tsunami detection buoys placed in the Pacific Ocean by NOAA. The upgraded DART buoys were originally developed to maintain but to mostly improve the timing of detection of a tsunami. With an improved detection time for tsunamis, that is more time to save lives, warning guidance and international coordination.

History

The DART buoy technology was developed at PMEL, with the first prototype deployed off the coast of

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

in 1995. In 2004, the DART® stations were transitioned from research at PMEL to operational service at the

National Data Buoy Center The National Data Buoy Center (NDBC) is a part of the National Oceanic and Atmospheric Administration's (NOAA) National Weather Service (NWS). NDBC designs, develops, operates, and maintains a network of data collecting buoys and coastal statio ...

(NDBC), and PMEL and NDBC received the Department of Commerce

Gold Medal A gold medal is a medal awarded for highest achievement in a non-military field. Its name derives from the use of at least a fraction of gold in form of plating or alloying in its manufacture. Since the eighteenth century, gold medals have bee ...

''"for the creation and use of a new moored buoy system to provide accurate and timely warning information on tsunamis"''. In the wake of the

2004 Indian Ocean earthquake An earthquake and a tsunami, known as the Boxing Day Tsunami and, by the scientific community, the Sumatra–Andaman earthquake, occurred at 07:58:53 local time (UTC+7) on 26 December 2004, with an epicentre off the west coast of northern Suma ...

and its subsequent

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explo ...

s, plans were announced to deploy an additional 32 DART II buoys around the world. These would include stations in the

Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...

and

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

for the first time. The United States' array was completed in 2008 totaling 39 stations in the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

, and

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

. The international community has also taken an interest in DART buoys and as of 2009

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

and

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...

have deployed DART buoys to use as part of each country's tsunami warning system. In the 2018 budget justification for NOAA, the

Trump Trump most commonly refers to: * Donald Trump (born 1946), 45th president of the United States (2017–2021) * Trump (card games), any playing card given an ad-hoc high rank Trump may also refer to: Businesses and organizations * Donald J. T ...

administration proposed eliminating the DART system as part of a 56% cut to the tsunami warning program.

Overview

Deep-ocean Assessment and Reporting of Tsunami (DART) buoy systems are made up of three parts. There is a bottom pressure recorder (BPR) anchored to the bottom of the sea floor. A moored surface buoy connects to the bottom pressure recorder via an acoustic transmission link. The link sends data from the anchored pressure recorder to the surface buoy. The surface buoy sends the data by radio to satellites such as the Iridium system. From the satellites, the data travels by radio to the ground, then to the system office by conventional telecommunications.(2015). Deep Ocean Tsunami Detection Buoys. Australian Government; Bureau of Meteorology. http://www.bom.gov.au/tsunami/about/detection_buoys.shtml The surface buoy has a two and a half meter diameter

fiberglass Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...

disk covered with foam and has a gross displacement of 4000 kg.Meinig, C., S.E. Stalin, A.I. Nakamura, H.B. Milburn (2005), Real-Time Deep-Ocean Tsunami Measuring, Monitoring, and Reporting System: The NOAA DART II Description and Disclosure. The

mooring line A mooring is any permanent structure to which a vessel may be secured. Examples include quays, wharfs, jetties, piers, anchor buoys, and mooring buoys. A ship is secured to a mooring to forestall free movement of the ship on the water. An ''an ...

connecting the surface buoy and the pressure recorder is a nineteen millimeter

nylon Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic. Nylon is a silk-like thermoplastic, generally made from petro ...

line that has a

tensile strength Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials t ...

of 7100 kg. The data sent from the anchored bottom pressure recorder to the surface buoy consists of the temperature and pressure of the surrounding sea water. It retrieves and releases data every 15 seconds to get an average reading of the current weather conditions. A very stable, long lived, very high resolution

pressure sensor A pressure sensor is a device for pressure measurement of gases or liquids. Pressure is an expression of the force required to stop a fluid from expanding, and is usually stated in terms of force per unit area. A pressure sensor usually act ...

is a critical enabling technology for DART's bottom pressure recorder. It is a resonant

quartz crystal Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

strain gauge A strain gauge (also spelled strain gage) is a device used to measure strain on an object. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an insulating flexible backing which supports ...

with a

bourdon tube Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressure ...

force collector. When compensated for temperature, this sensor has a pressure resolution of approximately 1mm of water when measuring pressure at a depth of several kilometers. Once the data reaches the surface buoy, the pressure data is converted to an average height of the waves surrounding the buoy. The temperature of the surrounding sea water is important to the calculations because temperature affects the water's density, thus the pressure, and therefore the sea temperature is required to accurately measure the height of the ocean swells. Because the swell sizes of the ocean vary constantly, the system has two modes of reporting data, standard mode and event mode.Deep-ocean Assessment and Reporting of Tsunamis (DART®) Description. (2011, July 27). Retrieved April 21, 2015, from http://www.ndbc.noaa.gov/dart/dart.shtml Standard mode is the more common mode. Every 15 minutes, it sends the estimated sea surface height and the time of the measurement. If the software receives data that is not within the recent data averages, the system automatically switches to event mode. Event mode transmits data every 15 seconds and calculates the average sea surface height and the time when data being recorded every minute. If no further data is received that is not out of the averages being calculated at the time, it switches back to standard mode after four hours. When NOAA released the first six DART buoys, their system only had a one way communication system. It was not until 2005 when the first generation of the DART buoy was upgraded to the second generation of the DART buoy. After 2005 the Dart buoys started using Iridium communication satellites that abled you to not only retrieved information but to also send information to a DART.Mungov, G., Eblé, M., & Bouchard, R. (2013). DART Tsunameter Retrospective and Real-Time Data: A Reflection on 10 Years of Processing in Support of Tsunami Research and Operations. Pure & Applied Geophysics, 170(9/10), 1369-1384. doi:10.1007/s00024-012-0477-5 The two-way communications between Tsunami Warning Centers and the pressure recorder made it possible to manually set DART buoys in event mode in case of any suspicion of a possible in-coming tsunamis. To make sure communications are always in contact and secure, the DART buoys have two communication systems; two independent and a redundant communication system. With these updated and reliable communicating systems, data can now be sent where it needs to be sent around the world.

References

External links

NOAA NDBC Deep-ocean Assessment and Reporting of Tsunamis (DART)
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br>Deep-ocean Assessment and Reporting of Tsunamis (DART)

Realtime DART buoy data
from the