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  • richardmitnick 9:30 am on September 27, 2019 Permalink | Reply
    Tags: "Distant Quake Triggered Slow Slip on Southern San Andreas", AGU/Eos, , , ,   

    From Eos: “Distant Quake Triggered Slow Slip on Southern San Andreas” 

    From AGU
    Eos news bloc

    From Eos

    23 September 2019
    Terri Cook

    A high-resolution map of surface displacements indicates that the 2017 Chiapas earthquake caused substantial creep along a segment of the San Andreas Fault, located 3,000 kilometers away.

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    The 2017 magnitude 8.3 Chiapas earthquake caused up to 15 millimeters of creep on the segment of the San Andreas Fault that runs along the northeastern edge of California’s Salton Sea. Credit: USGS/NASA’s Earth Observatory

    In the traditional model of the earthquake cycle, a seismic event occurs when an active fault abruptly releases strain that has built up over time. About 20 years ago, however, seismologists began finding that some faults, or sections of faults, can experience slow earthquakes—a gradual type of aseismic slip, or “creep,” that can last for months. Because both types of events release pent-up energy, determining the proportion of seismic versus aseismic slip along active faults is crucial for estimating their potential hazard.

    Although conventional interpretations predict that aseismic slip should occur at a roughly constant rate, geodetic observations have shown that at some locations fault creep is anything but steady. Measurements along the southern San Andreas Fault in California, one of the most studied examples of a creeping fault, have shown that this section often experiences bouts of accelerated creep and that these events can be spontaneous or triggered by seismic events. But the underlying conditions and mechanisms that cause slow slip are still poorly understood.

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    San Andreas Fault. Temblor

    Now Tymofyeyeva et al. [JGR Solid Earth] report detailed observations of a slow-slip event that occurred along the southern San Andreas Fault following the magnitude 8.3 earthquake that hit offshore Chiapas, Mexico, in September 2017. The team combined the results of field mapping with creepmeter and Sentinel-1 interferometric synthetic aperture radar observations to create a high-resolution map of surface displacements near the Salton Sea. The researchers then entered the results into numerical models to constrain the crustal properties that could generate the observed behavior.

    The results indicated that surface slip along the 40-kilometer-long section between Bombay Beach and the Mecca Hills accelerated within minutes of the Chiapas earthquake and continued for more than a year. The event resulted in total surface offsets that averaged 5-10 millimeters, comparable to the slow slip triggered by the 2010 magnitude 7.2 El Mayor-Cucapah (Baja) earthquake, even though the stress changes along the southern San Andreas due to the Chiapas earthquake were several orders of magnitude lower.

    The findings offer compelling evidence that the Chiapas earthquake triggered the 2017 slow-slip event along the southern San Andreas Fault, according to the researchers, and show that although shallow creep near the Salton Sea is roughly constant on decadal timescales, it can vary significantly over shorter periods of time. The authors conclude that the response of the southern San Andreas, and potentially other major faults, to different seismic events is complex and likely reflects crustal conditions as well as local creep history.

    See the full article here .

    Earthquake Alert

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    Earthquake Alert

    Earthquake Network projectEarthquake Network is a research project which aims at developing and maintaining a crowdsourced smartphone-based earthquake warning system at a global level. Smartphones made available by the population are used to detect the earthquake waves using the on-board accelerometers. When an earthquake is detected, an earthquake warning is issued in order to alert the population not yet reached by the damaging waves of the earthquake.

    The project started on January 1, 2013 with the release of the homonymous Android application Earthquake Network. The author of the research project and developer of the smartphone application is Francesco Finazzi of the University of Bergamo, Italy.

    Get the app in the Google Play store.

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    Smartphone network spatial distribution (green and red dots) on December 4, 2015

    Meet The Quake-Catcher Network

    QCN bloc

    Quake-Catcher Network

    The Quake-Catcher Network is a collaborative initiative for developing the world’s largest, low-cost strong-motion seismic network by utilizing sensors in and attached to internet-connected computers. With your help, the Quake-Catcher Network can provide better understanding of earthquakes, give early warning to schools, emergency response systems, and others. The Quake-Catcher Network also provides educational software designed to help teach about earthquakes and earthquake hazards.

    After almost eight years at Stanford, and a year at CalTech, the QCN project is moving to the University of Southern California Dept. of Earth Sciences. QCN will be sponsored by the Incorporated Research Institutions for Seismology (IRIS) and the Southern California Earthquake Center (SCEC).

    The Quake-Catcher Network is a distributed computing network that links volunteer hosted computers into a real-time motion sensing network. QCN is one of many scientific computing projects that runs on the world-renowned distributed computing platform Berkeley Open Infrastructure for Network Computing (BOINC).

    The volunteer computers monitor vibrational sensors called MEMS accelerometers, and digitally transmit “triggers” to QCN’s servers whenever strong new motions are observed. QCN’s servers sift through these signals, and determine which ones represent earthquakes, and which ones represent cultural noise (like doors slamming, or trucks driving by).

    There are two categories of sensors used by QCN: 1) internal mobile device sensors, and 2) external USB sensors.

    Mobile Devices: MEMS sensors are often included in laptops, games, cell phones, and other electronic devices for hardware protection, navigation, and game control. When these devices are still and connected to QCN, QCN software monitors the internal accelerometer for strong new shaking. Unfortunately, these devices are rarely secured to the floor, so they may bounce around when a large earthquake occurs. While this is less than ideal for characterizing the regional ground shaking, many such sensors can still provide useful information about earthquake locations and magnitudes.

    USB Sensors: MEMS sensors can be mounted to the floor and connected to a desktop computer via a USB cable. These sensors have several advantages over mobile device sensors. 1) By mounting them to the floor, they measure more reliable shaking than mobile devices. 2) These sensors typically have lower noise and better resolution of 3D motion. 3) Desktops are often left on and do not move. 4) The USB sensor is physically removed from the game, phone, or laptop, so human interaction with the device doesn’t reduce the sensors’ performance. 5) USB sensors can be aligned to North, so we know what direction the horizontal “X” and “Y” axes correspond to.

    If you are a science teacher at a K-12 school, please apply for a free USB sensor and accompanying QCN software. QCN has been able to purchase sensors to donate to schools in need. If you are interested in donating to the program or requesting a sensor, click here.

    BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

    Earthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the worlds largest strong-motion seismic network.

    Below, the QCN Quake Catcher Network map
    QCN Quake Catcher Network map

    ShakeAlert: An Earthquake Early Warning System for the West Coast of the United States

    The U. S. Geological Survey (USGS) along with a coalition of State and university partners is developing and testing an earthquake early warning (EEW) system called ShakeAlert for the west coast of the United States. Long term funding must be secured before the system can begin sending general public notifications, however, some limited pilot projects are active and more are being developed. The USGS has set the goal of beginning limited public notifications in 2018.

    Watch a video describing how ShakeAlert works in English or Spanish.

    The primary project partners include:

    United States Geological Survey
    California Governor’s Office of Emergency Services (CalOES)
    California Geological Survey
    California Institute of Technology
    University of California Berkeley
    University of Washington
    University of Oregon
    Gordon and Betty Moore Foundation

    The Earthquake Threat

    Earthquakes pose a national challenge because more than 143 million Americans live in areas of significant seismic risk across 39 states. Most of our Nation’s earthquake risk is concentrated on the West Coast of the United States. The Federal Emergency Management Agency (FEMA) has estimated the average annualized loss from earthquakes, nationwide, to be $5.3 billion, with 77 percent of that figure ($4.1 billion) coming from California, Washington, and Oregon, and 66 percent ($3.5 billion) from California alone. In the next 30 years, California has a 99.7 percent chance of a magnitude 6.7 or larger earthquake and the Pacific Northwest has a 10 percent chance of a magnitude 8 to 9 megathrust earthquake on the Cascadia subduction zone.

    Part of the Solution

    Today, the technology exists to detect earthquakes, so quickly, that an alert can reach some areas before strong shaking arrives. The purpose of the ShakeAlert system is to identify and characterize an earthquake a few seconds after it begins, calculate the likely intensity of ground shaking that will result, and deliver warnings to people and infrastructure in harm’s way. This can be done by detecting the first energy to radiate from an earthquake, the P-wave energy, which rarely causes damage. Using P-wave information, we first estimate the location and the magnitude of the earthquake. Then, the anticipated ground shaking across the region to be affected is estimated and a warning is provided to local populations. The method can provide warning before the S-wave arrives, bringing the strong shaking that usually causes most of the damage.

    Studies of earthquake early warning methods in California have shown that the warning time would range from a few seconds to a few tens of seconds. ShakeAlert can give enough time to slow trains and taxiing planes, to prevent cars from entering bridges and tunnels, to move away from dangerous machines or chemicals in work environments and to take cover under a desk, or to automatically shut down and isolate industrial systems. Taking such actions before shaking starts can reduce damage and casualties during an earthquake. It can also prevent cascading failures in the aftermath of an event. For example, isolating utilities before shaking starts can reduce the number of fire initiations.

    System Goal

    The USGS will issue public warnings of potentially damaging earthquakes and provide warning parameter data to government agencies and private users on a region-by-region basis, as soon as the ShakeAlert system, its products, and its parametric data meet minimum quality and reliability standards in those geographic regions. The USGS has set the goal of beginning limited public notifications in 2018. Product availability will expand geographically via ANSS regional seismic networks, such that ShakeAlert products and warnings become available for all regions with dense seismic instrumentation.

    Current Status

    The West Coast ShakeAlert system is being developed by expanding and upgrading the infrastructure of regional seismic networks that are part of the Advanced National Seismic System (ANSS); the California Integrated Seismic Network (CISN) is made up of the Southern California Seismic Network, SCSN) and the Northern California Seismic System, NCSS and the Pacific Northwest Seismic Network (PNSN). This enables the USGS and ANSS to leverage their substantial investment in sensor networks, data telemetry systems, data processing centers, and software for earthquake monitoring activities residing in these network centers. The ShakeAlert system has been sending live alerts to “beta” users in California since January of 2012 and in the Pacific Northwest since February of 2015.

    In February of 2016 the USGS, along with its partners, rolled-out the next-generation ShakeAlert early warning test system in California joined by Oregon and Washington in April 2017. This West Coast-wide “production prototype” has been designed for redundant, reliable operations. The system includes geographically distributed servers, and allows for automatic fail-over if connection is lost.

    This next-generation system will not yet support public warnings but does allow selected early adopters to develop and deploy pilot implementations that take protective actions triggered by the ShakeAlert notifications in areas with sufficient sensor coverage.

    Authorities

    The USGS will develop and operate the ShakeAlert system, and issue public notifications under collaborative authorities with FEMA, as part of the National Earthquake Hazard Reduction Program, as enacted by the Earthquake Hazards Reduction Act of 1977, 42 U.S.C. §§ 7704 SEC. 2.

    For More Information

    Robert de Groot, ShakeAlert National Coordinator for Communication, Education, and Outreach
    rdegroot@usgs.gov
    626-583-7225

    Learn more about EEW Research

    ShakeAlert Fact Sheet

    ShakeAlert Implementation Plan

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
    • Skyscapes for the Soul 2:40 pm on September 27, 2019 Permalink | Reply

      Very interesting that there is slow aseismic slip on my local part of the San Andreas. Explains why that fault hardly ever pops like the Borrego fault does.

      Like

  • richardmitnick 9:50 am on September 18, 2019 Permalink | Reply
    Tags: AGU/Eos, , , , , , , Provide a literal toehold for marine life like barnacles; coral; macroalgae; and mollusks., Pumice spewed out from an undersea volcano,   

    From EarthSky and Eos: “Volcanic Eruption Creates Temporary Islands of Pumice” 

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    From EarthSky

    From AGU
    Eos news bloc

    From Eos

    6 September 2019
    Katherine Kornei, Eos
    Eleanor Imster, EarthSky

    Sailing through rocks is anything but quiet. Last month, vessels in the South Pacific clinked and clanked their way through pumice spewed out from an undersea volcano. These temporary islands of volcanic rock, shaped and propelled by ocean currents, wind, and waves, provide a literal toehold for marine life like barnacles, coral, macroalgae, and mollusks.

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    Last month, rafts of pumice, spewed from an undersea volcano and spanning an area about the size of Washington, D.C., appeared in the South Pacific. Satellite image of a pumice raft floating near the Kingdom of Tonga. Image via NASA Earth Observatory.

    In early August, an unnamed volcano near the Kingdom of Tonga erupted roughly 40 meters underwater. The eruption sent pieces of gray pumice—porous rock filled with gas bubbles—floating to the surface. This volcanic debris, some fragments as large as beach balls, then aggregated into pumice “rafts” spanning roughly 200 square kilometers.

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    August 13, 2019. See detail below. Image via NASA Earth Observatory.

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    Detail of above image, taken August 13, 2019. Image via NASA Earth Observatory.

    Several sailing crews have encountered the rocks.

    “We were in a large area surrounded as far as the eye could see,” said Rachel Mackie, the purser and chef of Olive, a private vessel that sailed into a raft on 9 August near Late Island. There was a strong smell of sulfur, said Mackie, and Olive took a beating. “When the larger rocks hit the steel hull, it reverberated.”

    Several sailing crews have encountered the rocks.

    “We were in a large area surrounded as far as the eye could see,” said Rachel Mackie, the purser and chef of Olive, a private vessel that sailed into a raft on 9 August near Late Island. There was a strong smell of sulfur, said Mackie, and Olive took a beating. “When the larger rocks hit the steel hull, it reverberated.”

    Pumice rafts aren’t that common, said Martin Jutzeler, a volcanologist at the University of Tasmania in Hobart. “We see about two per decade.”

    Not all undersea eruptions produce them, but the rafts that do form tend to stick around. They can last for months or years until the pumice abrades itself into dust or finally sinks. And floating pumice can traverse long distances—when the same unnamed volcano near Tonga erupted in 2001, the pumice raft it created eventually arrived in Queensland, Australia, said Jutzeler.

    These transient, movable islands play an important role in marine ecosystems, scientists agree. Barnacles, coral, and macroalgae have all been found clinging to pumice, riding the waves en route to a new home.

    “It’s a perfect little substrate,” said Jutzeler.

    In 2012, Scott Bryan, a geologist at the Queensland University of Technology in Australia, and his colleagues showed that pumice rafts can significantly increase the dispersal of marine organisms. Bryan and his team found that more than 80 species traveled thousands of kilometers aboard pumice following the 2006 eruption of Home Reef Volcano in Tonga. “Pumice is an extremely effective rafting agent that can…connect isolated shallow marine and coastal ecosystems,” the researchers wrote in PLoS ONE.

    The long-distance journeys of pumice rafts are “definitely a way to get organisms to disperse widely,” said Erik Klemetti, a volcanologist at Denison University in Granville, Ohio, not involved in the research. But the idea that the stowaways aboard pumice rafts might replenish the Great Barrier Reef’s corals is wishful thinking, said Klemetti. “That’s probably an oversell.”

    Jutzeler and his colleagues are planning to study pumice from last month’s eruption. They’ve been in touch with several vessels that passed through the rafts, and they’ve arranged to analyze some of the rocks. (But the samples they’ve been promised are currently stuck in transit in Fiji, said Jutzeler.)

    By analyzing the chemistry of the pumice, Jutzeler and his colleagues hope to learn about the properties of the underwater volcanic eruption. For instance, was it eruptive or effusive?

    Studying the rocks’ surfaces will also reveal how quickly they’re being abraded, which will shed light on how rapidly volcanic dust is being deposited into the ocean. That’s important because some plankton feed on this volcanic debris, which can result in phytoplankton blooms, said Jutzeler.

    Jutzeler and other researchers are keeping a close watch on how the rafts are moving. Satellite imagery—from Terra, Aqua, Sentinel, and Landsat satellites, for instance—provides nearly daily updates. Ocean currents, wind, and waves sculpt and power the rafts, which now number in the hundreds.

    NASA Terra satellite

    ESA Sentinels (Copernicus)

    NASA/Landsat 8

    They’ll likely arrive in Fiji in a few weeks, Jutzeler predicts.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 11:23 am on June 18, 2019 Permalink | Reply
    Tags: "Ancient Water Underlies Arid Egypt", A hidden trove of groundwater is left over from the last ice age., AGU/Eos, Communities and agricultural operations in the Eastern Desert have an almost unlimited supply of groundwater without having to drill very deep., It’s a gorgeous supply of water clean not salty. You can drink it without any filtration or treatment., The Nubian Sandstone Aquifer System is the largest known fossil water aquifer in the world, The researchers used the radioactive isotope chlorine-36 which has a half-life of 300000 years to date groundwater samples collected from 29 wells scattered around the Eastern Desert., The water in the Nubian aquifer dates back to the Pleistocene epoch when Earth weathered periodic deep freezes., To date Libya is the only country to tap into the vast water reserves of the Nubian aquifer on a large scale., Vast quantities of groundwater fill an underground aquifer that spans four countries., We expected the water in the shallow aquifers to be less than 100 years old but some of the water samples were more than a thousand times that age.   

    From Eos: “Ancient Water Underlies Arid Egypt” 

    From AGU
    Eos news bloc

    From Eos

    6.18.19
    Mary Caperton Morton

    A hidden trove of groundwater is left over from the last ice age.

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    Many Egyptian wells are located in oases, where groundwater is close to the surface, creating a lush green habitat surrounded by desert. Credit: Mahmoud Sherif

    Aside from the Nile River’s green corridor, much of northeastern Africa is desert. But the arid landscape hides a secret: Vast quantities of groundwater fill an underground aquifer that spans four countries.

    A new study using chloride isotopes to date the groundwater under Egypt’s Eastern Desert has found that the water in smaller, shallower aquifers is refilled by the larger, deeper aquifer, where vast quantities of groundwater date to the last ice age.

    Most Egyptians live along the Nile and get their drinking and irrigation water from the river. Currently, just 7% of the country’s water usage is supplied by groundwater, but that number is expected to rise, said Mahmoud Sherif, a hydrogeochemist at the University of Delaware and lead author of the new study, published in Earth and Planetary Science Letters. “In the future, as Egypt’s population and agriculture expand, groundwater will become a more important resource.”

    The research team set out to date the age of the groundwater under the Eastern Desert to determine the aquifers’ responses to climate conditions and the recharge rates of shallower formations called alluvial aquifers. “These aquifers are closer to the surface and easier to access than the deeper Nubian aquifer,” Sherif told Eos.

    “We expected the water in the shallow aquifers to be less than 100 years old,” Sherif said, with the clock starting when the rainwater falls from the atmosphere onto Earth. Instead, some of the water samples were more than a thousand times that age.

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    Mahmoud Sherif, lead author of a new study on aquifers in Egypt’s Eastern Desert, collects a water sample from a groundwater pipe. Credit: Mahmoud Sherif

    The researchers used the radioactive isotope chlorine-36, which has a half-life of 300,000 years, to date groundwater samples collected from 29 wells scattered around the Eastern Desert. They found that the oldest samples in the alluvial aquifers were more than 200,000 years old. “This was really surprising,” Sherif said.

    Mixing with the Nubian aquifer helps explain the age: “This region is tectonically active and has a lot of deep-seated faults. Groundwater from the Nubian aquifer is making its way up along these faults and recharging the alluvial aquifers,” Sherif said.

    The Nubian Sandstone Aquifer System is the largest known fossil water aquifer in the world. Spanning more than 2 million square kilometers across Sudan, Chad, Libya, and Egypt, it contains more than 150,000 cubic kilometers of groundwater—more water than the Nile River discharges in 500 years.

    The water in the Nubian aquifer dates back to the Pleistocene epoch, when Earth weathered periodic deep freezes.

    “During the Ice Age, what is now desert was a lot greener and wetter,” said Cliff Voss, a hydrogeologist with the U.S. Geological Survey in Menlo Park, Calif., who was not involved in the new study. Today, the Nubian aquifer may receive a little water during flash flood season, but the recharge rate is “effectively zero,” Voss said.

    The new study offers new data on the little-studied Eastern Desert, and the findings match up well with previous studies of the Western Desert and the rest of the region underlain by the Nubian aquifer, said Voss.

    “In 2014, we mapped out the Nubian aquifer in the hopes that the four countries wouldn’t have to compete over their share of the water,” Voss said of his 2014 study published in the Hydrogeology Journal. “Fortunately, all four countries essentially have water forever, especially Egypt and Libya.”

    To date, Libya is the only country to tap into the vast water reserves of the Nubian aquifer on a large scale. The pipelines known as the Great Man-Made River carry water from 1,300 wells more than 2,800 kilometers inland across the desert to the coastal cities of Tripoli, Benghazi, and Sirte.

    The connection between the alluvial aquifers and the Nubian aquifer means that communities and agricultural operations in the Eastern Desert have an almost unlimited supply of groundwater without having to drill very deep.

    “It’s a gorgeous supply of water, clean, not salty,” Voss says. “You can drink it without any filtration or treatment.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 9:16 am on May 10, 2019 Permalink | Reply
    Tags: AGU/Eos, Marine Virus Survey Reveals Biodiversity Hot Spots", Ocean samples collected from around the world produced a twelvefold increase in the number of marine viruses known., , Tara Oceans expedition   

    From Eos: “Marine Virus Survey Reveals Biodiversity Hot Spots” 

    From AGU
    Eos news bloc

    From Eos

    3 May 2019
    Kimberly M. S. Cartier

    Ocean samples collected from around the world produced a twelvefold increase in the number of marine viruses known. A portion of the Arctic Ocean has “surprisingly high diversity.”

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    The research ship Tara, seen here, sailed around the world for 3 years. Hundreds of experts collected ocean samples that researchers have used to vastly expand the number of known marine viral populations. Credit: Tara Foundation

    Microbes are the foundation of marine ecosystems, and marine viruses shape the biodiversity, life span, and evolution of microbial communities. A recent study in Cell presented the most extensive catalog of marine viruses to date, genetically identifying more than 180,000 new viral populations around the world.

    “Marine viruses infect and lyse about one third of cells per day, transfer genes from one host to another, and metabolically reprogram their hosts,” Matthew Sullivan, principal investigator on the project and a microbiologist at The Ohio State University in Columbus, told Eos. “Cataloging them helps us understand how viruses modulate the microbial processes that underpin the marine ecosystem.”

    The researchers also identified five distinct ecological zones for marine viruses, including two subzones in the Arctic Circle. Advanced genetic sequencing showed that viral populations in the Arctic, the region most affected by climate change, are among the most biodiverse in the world.

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    Experts collect water samples during the Tara Oceans expedition. Credit: A. Deniaud/Fondation Tara Ocean

    The researchers analyzed water samples collected by the Tara Oceans expedition*, a global oceanographic research and survey effort that involved dozens of labs and hundreds of researchers, Sullivan said. The samples represent 145 ocean locations around the world, including 41 new samples from the Arctic Ocean. Each water sample hosts a unique virus habitat, or virome.

    *The expedition has enjoyed the support of France’s National Centre for Scientific Research (CNRS), the European Molecular Biology Laboratory (EMBL), France’s Alternative Energies and Atomic Energy Commission (CEA) and many public and private organizations.

    The team had analyzed some of these viromes [Nature] previously and identified around 15,000 viral populations “using state-of-the-art [techniques] at the time,” Sullivan said. “This new paper then builds upon this to take advantage of deeper sequencing, new assembly algorithms, and new virus identification algorithms, which all added quite a bit to this current data set.”

    By using more advanced gene sequencing methods, the team identified nearly 200,000 marine viral populations. This is a roughly twelvefold increase in the number of known marine viruses.

    Ninety-two percent of the viruses the team identified were new discoveries, and about half of those new marine viruses came from the Arctic.

    “This is a truly impressive data set,” said viral ecologist Joanne Emerson, who was not involved with this research. “At nearly 200,000 viral populations, the scale is astounding.” Emerson is an assistant professor at the University of California, Davis.

    Defining Populations

    Viral ecologists have struggled with defining the boundaries of viral species because RNA viruses and single-strand DNA viruses evolve very quickly. They typically group viruses into “populations” along a common genetic lineage, but this process requires extensive data sets of deep genetic sequencing and has been done for only a few subgroups of viruses.

    With the new catalog, the researchers were able to test whether this approach to viral populations applies more generally. They found that, yes, it does.

    “The research supports a prior definition of viral populations,” Jennifer Brum, an oceanographer and marine viral ecologist at Louisiana State University in Baton Rouge, told Eos. “This is exciting because our field has been struggling for some time with the problem of how to count different types of viruses—something that is necessary to quantitatively compare viral assemblages in various locations.”

    “Without a definition for viral populations,” Brum said, “we cannot begin to assess the environmental conditions that drive their distribution, dynamics, and effects on Earth’s ecosystem.” Blum was not involved with this research.

    “This work includes the strongest evidence thus far for a robust, broadly applicable, sequence-based definition of a viral ‘species,’ providing the currency to probe viral impacts on and responses to ecosystem processes,” Emerson said.

    Surprising Arctic Biodiversity

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    The Tara Oceans expedition collected 41 new samples from the Arctic Circle, from which the researchers identified more than 75,000 new marine viral populations. Credit: Tara Foundation

    The researchers also found that virus populations were grouped into five distinct ecologic zones: Arctic, Antarctic, deep sea, temperate-tropical midlevel, and temperate-tropical near surface. This grouping suggests that water temperature is a major driver in structuring viral ecologic zones, according to the researchers, which matches their earlier virus research as well as global microbial surveys.

    The team then calculated the biodiversity of viral populations within each ecologic zone. They found that the Antarctic and midlevel zones had the lowest biodiversity. The near-surface zone and part of the Arctic zone were biodiversity hot spots.

    The Arctic biodiversity surprised the team because current conventions assume that biodiversity decreases closer to Earth’s poles.

    “Half of the oxygen we breathe comes from the oceans,” Sullivan said, “and half of the carbon dioxide that we humans release into the atmosphere is absorbed by the oceans and its marine microbes.” This marine virus catalog provides a baseline that scientists can use when evaluating the ecosystem changes caused by rising Arctic sea temperatures, he said.

    “The finding from this paper that the Arctic Ocean has surprisingly high diversity of viruses is very interesting,” Brum said, “especially because that region is being significantly impacted by climate change.”

    “There are a number of dots yet to be connected,” Emerson said, but the connection between sea temperature and viral biodiversity “suggests the potential for climate effects on viral communities that could ricochet through ocean food webs.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 11:07 am on May 3, 2019 Permalink | Reply
    Tags: "Untangling a Web of Interactions Where Surf Meets Coastal Ocean", AGU/Eos, ,   

    From Eos: “Untangling a Web of Interactions Where Surf Meets Coastal Ocean” 

    From AGU
    Eos news bloc

    From Eos

    2 May 2019
    James Lerczak, John A. Barth, Sean Celona, Chris Chickadel, John Colosi, Falk Feddersen, Merrick Haller, Sean Haney, Luc Lenain, Jennifer MacKinnon, James MacMahan, Ken Melville, Annika O’Dea, Pieter Smit, and Amy Waterhouse

    In 2017, an ocean research team launched an unprecedented effort to understand what drives ocean currents in the overlap regions between surf zones and continental shelves.

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    Point Sal protrudes from the California coastline in this aerial view of the study site for the 2017 Inner Shelf Dynamics Experiment. A wide variety of instruments, situated aboard ships, boats, and satellites and deployed in the ocean and on land, collected massive amounts of data on the characteristics and movements of ocean water in this region where sea and shore interact. Credit: Gordon Farquharson

    Winds and waves drive the coastal ocean’s waters to flow and mix. So do differences in temperature, salinity, the topography of the seafloor, and a host of other factors. All these factors overlap and interact in complex patterns that influence where ocean creatures make their homes and where waterborne materials, both natural and human made, are dispersed along our coasts. The coastal physical oceanography community has made great strides in understanding the dynamics that drive water motions and density distributions in the coastal ocean. They have also worked to demonstrate the importance of these dynamics to coastal communities and ecosystems.

    Over the past several decades, oceanographers have undertaken large field experiments to quantify coastal dynamics and their impacts. Often, these studies have been partitioned into specific regions of the coastal ocean and focused on specific processes: wind effects over the continental shelf or wave effects close to shore, for example. However, in the inner shelf region, where the continental shelf and shore regions overlap and their processes interact, challenges to our understanding persist [Lentz and Fewings, 2012 Annual Review of Marine Science ].

    In the summer and fall of 2017, a group of researchers sponsored by the U.S. Office of Naval Research (ONR) undertook an unprecedented seagoing and numerical ocean modeling experiment. The Inner Shelf Dynamics Experiment investigated the nonlinear, interacting processes that drive currents and transport in this important coastal region.

    Studying Sea and Shore and Where They Overlap

    The Coastal Ocean Dynamics Experiment [(CODE) Journal of Geophysical Research] of the early 1980s was a major collaborative effort to explore wind-driven circulation on the continental shelf in northern California [Beardsley and Lentz, 1987 (see link at CODE above)]. These experiments produced a data set unprecedented for its time, and they inspired and motivated many field and numerical experiments on stratified wind-driven flows over midcontinental shelves (water depths around 50–100 meters).

    Closer to shore, wave dynamics and wave-driven transport have been studied in great detail by the nearshore science community. In particular, a suite of experiments, including Duck94 and SandyDuck, at the U.S. Army Corps of Engineers Field Research Facility in Duck, N.C., was seminal in expanding knowledge of surf zone dynamics [e.g., Long and Sallenger, 1995].

    The less explored inner shelf, with typical water depths ranging from 5 to 50 meters, is the region where the surf zone meets and interacts with the coastal ocean. Within the surf zone, breaking waves dominate the dynamics and can drive large wave-averaged flows, such as rip currents. On the density-stratified continental shelf, several mechanisms compete to drive currents, including wind forcing, bathymetric influences, tides, submesoscale eddies, and shoaling and breaking nonlinear internal bores and waves.

    At the inner shelf, the dynamics that typify both the nearshore and continental shelf are in play. These overlapping dynamics lead to highly nonlinear, interacting processes that regulate the alongshore and across-shore transport of water, water properties (e.g., temperature), and waterborne materials (e.g., sediment, dissolved gases, plankton, and contaminants). These inner shelf processes vary over a wide range of spatial and temporal scales, and their interactions are poorly understood. In addition, interactions between currents and variable coastal bathymetric features (e.g., headlands) enhance the complexity of transport.

    The Inner Shelf Dynamics Experiment aims to understand the interacting nonlinear dynamics of the inner shelf and identify and quantify the processes that drive the exchange of water properties and waterborne materials across this region over a range of temporal and spatial scales.

    This ONR Departmental Research Initiative is centered around an extensive, multi-institutional field experiment coordinated with numerical modeling efforts to study a 50-kilometer stretch of the central California coast that straddles Point Sal and includes the region offshore of Vandenberg Air Force Base (Figure 1).

    2
    Fig. 1. (a) Map of the Inner Shelf Dynamics Experiment study site, showing locations of moorings and bottom landers and measurement footprints of coastal X band and coherent radar systems. Contour lines represent water depth in meters. (b) Composite image of X band radar ocean surface measurements (time averaged to remove surface gravity waves) showing surface signatures of inner shelf processes, including coherent internal bore fronts and high-frequency internal waves. Credit: (a) Jim Lerczak; (b) Sean Celona

    Our overarching goals are the following:

    improving our understanding of inner shelf hydrodynamics;
    developing and improving the predictive capability of a range of numerical models to simulate the three-dimensional circulation, density, and surface wave field across the inner shelf;
    coupling a suite of remote sensing platforms with in situ measurement arrays to produce a synoptic description of inner shelf processes across the study region.

    Sensors at Sea and in the Sky

    During the field component of the experiment, which took place from late August to November 2017, we obtained a diverse and unprecedented suite of in situ and remote sensing measurements.

    Moorings and Landers. We installed a broad array of 176 mooring and bottom lander platforms to make in situ time series measurements that spanned the continental shelf to the nearshore in water depths ranging from 150 to 6 meters (Figures 1a and 2). These measurements included temperature, salinity, velocity, surface wave, turbulence, and meteorological measurements. The array focused on three regions with different bathymetric features: a region with a fairly straight, planar beach (Oceano); a coastal headland (Point Sal); and a region between two coastal capes (Vandenberg).

    2
    Fig. 2. Twelve-hour time series of density anomaly (observed density minus 1,000 kilograms per cubic meter; contoured) and cross-shore current (color shaded) as a function of depth from the mooring-lander pair at a water depth of 50 meters at the Oceano array. A sharp internal bore front arrives at this location at 14:30 Coordinated Universal Time (UTC). A packet of high-frequency internal waves arrives at 22:00 UTC. Credit: Jim Lerczak

    Shipboard Surveys. We conducted coordinated shipboard surveys during three intensive operation periods. We used three ships: R/Vs Sally Ride, Oceanus, and R. G. Sproul (the Sproul was funded with University of California Ship Funds). We also used four boats: R/Vs Kalipi, Sally Ann, Sounder, and Sand Crab.

    3
    Rapid profiling with a conductivity, temperature, depth (CTD) package across an internal bore front (long foam line) near the Oceano array on the small boat R/V Kalipi (Oregon State University). Credit: Jim Lerczak

    Instruments deployed from the vessels included acoustic Doppler current profilers (ADCPs); profiling conductivity, temperature, depth (CTD) packages; towed undulating vehicles; echo sounders; and a profiling turbulence sensor package. We deployed a bow chain to obtain highly spatially resolved temperature, salinity, and turbulence measurements in the upper 20 meters of the water column (Figures 3 and 4). In addition, we installed marine X band radars on two of the ships to measure surface gravity waves and wave-averaged surface currents.

    3
    Fig. 3. High-resolution temperature cross-shore section of a sharp front in the upper water column at the Oceano array of the Inner Shelf Dynamics Experiment study site at a water depth of 40 meters, obtained from the bow chain attached to the R/V Sally Ride. Credit: Sean Haney and Jennifer MacKinnon

    4
    Fig. 4. This longwave infrared image of sea surface temperature near Point Sal on 11 September 2017 at 10:41 UTC shows a curving wake (indicated by the white dashed line) caused by flow separation in the lee of Point Sal. Black squares are locations of ADCP landers, and black and gray vectors show near-surface and near-bottom currents, respectively (10-minute averages). Gray dash-dotted lines indicate repeated transect lines of the small boats R/V Sally Ann (Scripps Institution of Oceanography) and R/V Sounder (Applied Physics Laboratory, University of Washington). Credit: Mike Kovatch, Ken Melville, and Luc Lenain

    The coordinated surveys were designed to resolve shoaling nonlinear internal waves, wind-driven circulation, flow separation at headlands, and interactions between internal waves, headland flows, and rip currents ejected from the surf zone (Figure 5).

    5
    Fig. 5. Time-averaged X band radar images showing an internal bore front approaching the surf zone east of the Oceano array and interacting with an ejecting rip current. Credit: Annika O’Dea

    Drifters. We deployed more than 50 real-time tracking, GPS-equipped drifters from small boats on daily missions throughout the intensive operation periods. Drifters were released in coordinated patterns to measure surface transport pathways, dispersion, and vorticity across various spatial scales. Several of the drifters were integrated with additional instrumentation, including Doppler profilers for turbulence measurements, conductivity and temperature probes, and meteorological sensors.

    Remote Sensing. Several remote sensing platforms incorporated a range of sensors to measure surface signatures of inner shelf processes. Two aircraft were equipped with optical and thermal infrared cameras (Figure 6), lidar, and interferometric synthetic aperture radar (SAR) sensors.

    Four coastal X band radar systems had sampling footprints that spanned the entire study site (Figures 1 and 5). They measured surface gravity waves; tracked internal waves; and identified buoyant fronts, eddies, and small-scale instabilities. We also acquired more than 50 satellite SAR and optical images. In addition, we used small aerial drones with both optical and infrared cameras to characterize smaller-scale features of interest.

    6
    Fig. 6. Aerial photographs of an internal bore front propagating toward Mussel Point. The photo on the right shows instabilities developing on the internal bore front. Credit: Nick Statom

    State-of-the-Art Instrumentation. The cutting-edge technology used in this experiment, which included off-the-shelf sensors as well as highly integrated, in-house instrumentation, allowed us to take novel measurements and approaches. Moored instrumentation (e.g., fast-response thermistors and five-beam ADCPs) collected time series data for the 2.5-month duration of the experiment with sampling frequencies as high as 100 data points per second.

    We used satellite telemetry to transmit many of the observations, allowing us to incorporate real-time data acquisition directly into multiscale forecast models. For example, observations from Spoondrift Spotter directional wave buoys were transmitted to a computational back end to reconstruct a data-driven, real-time regional surface wave nowcast.

    GusT, a new turbulence probe, was developed and constructed under this project by Jim Moum of Oregon State University. This probe has sensors to measure turbulent temperature and current fluctuations as well as absolute speed. Approximately 80 GusTs were deployed on bottom landers, mooring lines, profiling sensor packages, and the bow chain. They provided turbulence measurements over a range of locations, within the upper and bottom boundary layers as well as within the interior of the water column.

    Coupled, Multiscale Forecast and Hindcast Simulations. We also developed a multiscale ocean modeling system for the experiment region. We used regional ocean, atmosphere, and wave models to prescribe open boundary conditions and atmospheric forcing. We are using nested multigrid simulations with horizontal resolutions ranging from 3 kilometers to 22 meters to simulate observed ocean variability at the experiment study site and provide an integrated model-observation platform to address the key science questions.

    Putting the Data to Use

    The Inner Shelf Dynamics Experiment is unprecedented in the scope of processes sampled in the coastal ocean, the number of instruments used, and the diversity of measurement and modeling platforms used.
    The Inner Shelf Dynamics Experiment is unprecedented in the scope of processes sampled in the coastal ocean, the number of instruments used, and the diversity of measurement and modeling platforms used. We have used this experiment to collect an unparalleled data set, which we are analyzing to quantify the dominant and interacting physical processes at work in the inner shelf and to determine the spatial scales and temporal variability of transport pathways in the region.

    The observations from this new field experiment will test and improve model predictions and quantify remotely sensed measurements, encompassing a broad range of mechanisms, including surface gravity and internal waves, Stokes drift and rip currents, submesoscale eddies, and wind-driven flows. The experiment and the data set it produced will keep coastal physical oceanographers busy in the decades to come.

    More information about the experiment is available at http://www.apl.washington.edu/innershelf and scripps.ucsd.edu/projects/innershelf.

    See the full article here .

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