Burazer M.,Geophysical Institute |
Zitko V.,Geophysical Institute |
Radakovic D.,Geophysical Institute |
Parezanovic M.,Geophysical Institute
Journal of Applied Geophysics | Year: 2010
In the area near the village of Jazak (southern part of Fruška Gora mountain, Serbia), hydrogeological investigations were carried out for the purpose of finding a water supply source to provide an adequate volume of water for a mineral water bottling plant. The first exploratory borehole (IBJf-1) penetrated a water-bearing layer of Miocene organogenic limestones. This aquifer has a thickness of about 30. m and a yield of only 2.2. l/s, which falls short of the required water volume (5. l/s).The objective of further exploration was to define the attitude and extension of the aquifer and thus select a more favourable site for a new exploratory borehole that would secure the required volume of water. For this purpose, geophysical exploration was carried out in 2003 through vertical electrical sounding (VES) and high-resolution 3D reflection seismic methods. The VES measurements enabled determination of aquifer depth and indicated that the water-bearing strata extend over the entire area studied. However, because of the equivalence problem, it was not possible to determine the thickness of the water-bearing stratum based solely on the VES data. Thus, the 3D seismic method was used in the second stage of investigation. A low-cost 3D seismic survey was carried out with fixed receiver lines, using a vibrator as the source of the seismic waves.From the 3D seismic data it was possible to determine the aquifer thickness. The depth of the aquifer determined by interpretation of the 3D seismic data was in accordance with the depth determined by the VES method. Based on the assumption that the hydraulic conductivity of this formation is identical or similar over the entire area, as well as the fact that the first well showed the presence of a subartesian aquifer, we proposed drilling another borehole (IBJf-2) in the zone where the data indicated that the water-bearing stratum was much thicker. The data obtained by drilling and coring were in agreement with the predicted aquifer thickness. Pumping tests showed that the water discharge in borehole IBJf-2 was 6. l/s.The results show that the objective of delineating the groundwater body by combined application of two geophysical methods (VES and 3D seismic) was successfully performed. © 2010 Elsevier B.V.
Roy T.,French Climate and Environment Sciences Laboratory |
Bopp L.,French Climate and Environment Sciences Laboratory |
Gehlen M.,French Climate and Environment Sciences Laboratory |
Schneider B.,Institute of Geosciences |
And 7 more authors.
Journal of Climate | Year: 2011
The increase in atmospheric CO2 over this century depends on the evolution of the oceanic air-sea CO2 uptake, which will be driven by the combined response to rising atmospheric CO2 itself and climate change. Here, the future oceanic CO2 uptake is simulated using an ensemble of coupled climate-carbon cycle models. The models are driven by CO2 emissions from historical data and the Special Report on Emissions Scenarios (SRES) A2 high-emission scenario. A linear feedback analysis successfully separates the regional future (2010-2100) oceanic CO2 uptake into a CO2-induced component, due to rising atmospheric CO2 concentrations, and a climate-induced component, due to global warming. The models capture the observationbased magnitude and distribution of anthropogenic CO2 uptake. The distributions of the climate-induced component are broadly consistent between the models, with reduced CO2 uptake in the subpolar Southern Ocean and the equatorial regions, owing to decreased CO2 solubility; and reduced CO2 uptake in the midlatitudes, owing to decreased CO2 solubility and increased vertical stratification. The magnitude of the climate-induced component is sensitive to local warming in the southern extratropics, to large freshwater fluxes in the extratropical North Atlantic Ocean, and to small changes in the CO2 solubility in the equatorial regions. In key anthropogenic CO2 uptake regions, the climate-induced component offsets the CO2-induced component at a constant proportion up until the end of this century. This amounts to approximately 50% in the northern extratropics and 25% in the southern extratropics and equatorial regions. Consequently, the detection of climate change impacts on anthropogenic CO2 uptake may be difficult without monitoring additional tracers, such as oxygen. © 2011 American Meteorological Society.
Kasatkina E.,Novosibirsk State University |
Koulakov I.,Novosibirsk State University |
West M.,Geophysical Institute |
Izbekov P.,Geophysical Institute
Journal of Geophysical Research: Solid Earth | Year: 2014
We present seismic velocity models of the area beneath Redoubt Volcano (Alaska) corresponding to two time periods, before and after the strong eruption that occurred in March 2009. The calculations were based on tomographic inversion of P and S arrival time data recorded by 19 stations using the local earthquake tomography code LOTOS. We performed thorough analysis of the results based on synthetic tests in each of the time periods that allow real-time variations in structure to be distinguished from artifacts caused by changes in the observation system configurations. In the resulting images corresponding to the period before the eruption, the summit area is characterized by higher values of both P and S velocities and moderate values of the Vp/Vs ratio. This may correspond to the rigid igneous rocks composing the body of the volcano that lack significant liquid content. In the second episode corresponding to the time of the eruption, the P velocity remained high, whereas the S velocity became very low. The anticorrelation of P and S anomalies in the summit area produced a Vp/Vs ratio as high as 2.2, which is seen down to 2-3km depth. This indicates presence of mobile phase at shallow depth beneath the volcano, which can be either in the form of partial melt or fluid-saturated rocks. Key Points Redoubt Volcano structure is studied using the local earthquake tomography Areas of high Vp/Vs ratio represent magma or fluid conduits beneath the volcano Vp/Vs ratio strongly increases during the eruption of Redoubt in March 2009 ©2014. American Geophysical Union. All Rights Reserved.
Tran T.T.,University of Alaska Fairbanks |
Molders N.,University of Alaska Fairbanks |
Molders N.,Geophysical Institute
Atmospheric Environment | Year: 2012
The Alaska-adapted WRF/Chem was used to examine the benefits of the proposed North American Emission Control Area (ECA) for air quality along the Alaska coasts. Simulations were performed alternatively assuming the emissions of 2000, and the emissions of 2000 reduced by the proposed ECA-reductions. In response to the emission reductions, reductions in sulfur (nitrogen) compounds reached up to 9km (2km) height. Reductions of sulfate- and nitrate-in-clouds were highest at the top of the atmospheric boundary layer. The strongest reductions occurred over the ECA and the international sea-lanes for sulfur- and nitrogen-compounds, respectively. Along the Gulf of Alaska, sulfur- and nitrogen-compound concentrations decreased significantly in response to the reduced ship-emissions. They decreased over Alaska despite of unchanged emissions in Alaska. PM 2.5-speciation only marginally changed in response to the reduced ship-emissions. © 2011 Elsevier Ltd.
News Article | February 22, 2017
In the middle of a snow-draped forest in Alaska, a long four-hour drive east from Anchorage, sits a cleared 30-acre field where 180 silver poles sprout from the ground and reach 22 meters into the air. During four nights this week the poles—actually interconnected radio antennae—will spring to life after three years of dormancy, and heat the highest wisps of our atmosphere directly above. The antennas belong to the High Frequency Active Auroral Research Program (HAARP), a former U.S. military facility near the hamlet of Gakona. The array will beam 2.1 megawatts of radio energy into the ionosphere—the region that starts at 100 kilometers above the ground, where solar photons and charged particles crash into Earth’s atmosphere. There the radio signals will excite electrons and turn them into waves of relatively hot ionized gas, or plasma, in a narrow slice of sky. The hope is to better understand activity that hampers satellites as well as some elusive features of radio wave physics. The antenna forest was originally funded by the U.S. Navy and Air Force to improve their navigation and communication signals bouncing around the planet. Since its first transmissions in 1999, however, it has been accused of doing much more. Iran blamed HAARP operations for floods, the late Venezuelan leader Hugo Chavez charged it with triggering 2010’s devastating Haiti earthquake and legions of other conspiracy theorists have accused it of everything from mind control to stealing souls. In fact the only thing the military was interested in controlling was the hot plasma, says Bill Bristow of the University of Alaska Fairbanks, who is HAARP’s chief scientist. The plasma can distort or delay satellite transmissions and GPS signals. The armed services wanted to know whether those perturbations could be manipulated from the ground to eliminate such problems, and perhaps enable new communications and radar technologies. So they built HAARP, the world’s most powerful ionosphere heater. More than a decade of experiments, however, failed to produce any major breakthroughs. Eventually the military threw in the towel. In 2014 David Walker, then deputy assistant secretary of the Air Force for Science, Technology and Engineering, told a Senate committee, “If there is not somebody who wants to take over the management and the funding of the site…we plan to do a dismantle of the system.” The pending demise caught the attention of scientists at U.A. Fairbanks’s Geophysical Institute. “We felt that there was a large investment of public money that should not just be destroyed,” Bristow says. “There’s a lot of scientific work yet to be done, so we wanted to give it a go.” The Air Force officially handed over HAARP’s keys to the institute in 2015. Now after years of repairs, upgrades and fund-raising, HAARP is about to embark on its first scientific campaign under civilian control. Much of the work is a continuation of studies that began under the military. Plasma scientists, for example, will hunt for an elusive phenomenon called two-plasma decay instability. This involves an electromagnetic signal decaying into two electron plasma waves. Understanding this instability is key to some experimental nuclear fusion reactions but it has never been observed for high-frequency radio waves. The facility is also going to be generating artificial aurorae. At full power, HAARP’s transmitter can produce a glowing plasma high in the sky that, although not as bright as the natural aurora borealis, is visible to the naked eye. Producing artificial aurorae has taught scientists unexpected lessons about how gases are ionized in the ionosphere, a process that helps protect Earth from harmful ultraviolet solar radiation. “Understanding how energy from the sun flows into the upper atmosphere is important for understanding the effect on Earth from extreme solar events,” Bristow says. And the military could not quite let go of HAARP altogether. The Naval Research Laboratory thinks it can use the ionosphere to improve spy satellite operations. The lab will be running an experiment where it bounces radio signals off the ionosphere and then back down to the sea, hundreds of kilometers over the horizon. Satellites overhead will then try to use the radio reflections from the ocean surface to detect ships or ice. Because the satellites will rely on the facility’s signals, and not their own, this method could enable them to stay cloaked from prying eyes and conserve their own energy. The success of these initial experiments will be critical in demonstrating the long-term viability of HAARP to the agencies funding the efforts along with the navy: the National Science Foundation and U.S. Department of Energy. “This beauty of HAARP is that it’s a way to turn the ionosphere into a plasma lab where we can control the knobs and timing,” says Mark Moldwin, a professor of space sciences at the University of Michigan who is not involved with the current research. “It has essentially come back from the dead and the community is hopeful that its continued operation will enable education and research opportunities.” U.A. Fairbanks says it will support the facility for about two more years. Then it could pull the plug if more sponsors are not forthcoming. But for the week ahead the biggest risk is nature itself, Bristow says: “If it’s cloudy, we won’t see the auroras, and a solar storm could wipe out our ability to do any heating at all.” There is nothing the facility can do about clouds and storms. Despite the rumors, Bristow says, HAARP has never been able to control the weather.
News Article | December 10, 2015
The likelihood of El Niño shaping up to be as disastrous as in 1997-98 is now "very low," said Ken Takahashi, the lead El Niño investigator at Peru's Geophysical Institute. "During the anomaly of 1997, coastal temperatures in Peru were almost double what they are now, so it would be very difficult to reach those levels," Takahashi said. Enfen, the Peruvian bureau tasked with forecasting El Niño, had previously forecast a 50 percent chance of a "strong" El Niño in the summer, which spans from December to March in the Southern Hemisphere. It now sees a 35 percent chance it will be strong and a 50 percent chance it will become moderate. However, Takahashi said El Niño could still bring heavy rains, especially to Peru's northern coast, and may cause a drought in Andean regions. Australia has also said that the event has shown signs of easing. A naturally occurring phenomenon, which can have widespread effects on agriculture, fisheries, water and health, El Niño is driven by warm surface water in the eastern Pacific Ocean. The World Meteorological Organization said last month that the current El Niño was already "strong and mature" and the biggest in more than 15 years.
News Article | March 28, 2016
The Pavlof Volcano spews ash in the Aleutian Islands of Alaska in this handout photo released to Reuters on March 28, 2016 by Alaska Volcano Observatory. The Pavlof Volcano spews ash in the Aleutian Islands of Alaska in this U.S. Coast Guard photo taken March 28, 2016. Picture taken March 28, 2016. Mount Pavlof, one of the most active volcanoes on the peninsula, began erupting shortly after 4:00 p.m. Alaska Daylight Time on Sunday, said Jessica Larsen, coordinating scientist with the University of Alaska Geophysical Institute. "Pavlof is known to us for having a pretty quick onset to eruptions, it doesn't always give us long precursory signals," Larsen said. "If you look at some of the seismic data that we have, the intensity really ramped up pretty fast. It was quite abrupt," she said. Photos on the Alaska Volcano Observatory website showed the plume towering over the icy slopes of Mount Pavlof and drifting to the northwest. The Federal Aviation Administration issued a "red" aviation alert in response to the 20,000-foot-high ash cloud, which required that flights to be re-routed. The alert could affect local and regional air traffic, as well polar routes and cargo flights from Anchorage. Larsen said the eruption did not pose any immediate danger to nearby communities on the peninsula, which were monitoring the ash fall. The closest residential area is Cold Bay, located 37 miles (60 km) southwest of Pavlof. There have been more than 40 eruptions from Pavlof, including between May and November of 2014, when ash plumes also triggered aviation warnings. Such events can last weeks or months. "This 20,000-foot ash cloud is not unusual for Pavlof at all," Larsen said, adding that the highest recorded plume from the volcano was 49,000 feet.
News Article | December 16, 2015
San Diego's city council unanimously voted Tuesday to adopt a plan to power the city entirely with renewable energy by 2035, joining cities like San Francisco, Paris and Vancouver, Canada, in setting ambitious targets for reducing greenhouse gas emissions over the next several decades. Spearheaded by Republican Mayor Kevin Faulconer, who took office last year, San Diego's Climate Action Plan puts the city on track to halve its greenhouse gas emissions by 2035. The city is the largest in the U.S. to adopt a 100 percent renewable energy plan. The blueprint also goes beyond California's statewide goal of 50 percent clean energy in the next 15 years. Bloomberg: Solar, Wind Shares Jump as U.S. Nears Deal on Tax Credits Shares of U.S. clean-energy companies jumped Tuesday as Congress neared a deal that would revive or extend tax credits for the wind and solar industries. SunEdison Inc., the world’s biggest renewable-energy developer, rose 13 percent at the close in New York while rooftop solar provider Sunrun Inc. gained 4.3 percent. Wind-farm builder Pattern Energy Group Inc. climbed 4 percent. While a deal still isn’t certain, Republicans and Democrats are discussing five-year renewals of the two chief clean-energy subsidies in exchange for an end to the 40-year-old ban on U.S. oil exports, two energy lobbyists familiar with the negotiations told Bloomberg. Climate Progress: After Paris Climate Agreement, Countries ‘Are Not Going Back,' Says Todd Stern Speaking just days after the announcement of a historic climate deal in Paris, Todd Stern, U.S. Special Envoy for Climate Change, seemed pretty pleased with the international agreement that came out of the talks. “We got an awful lot of what we wanted,” Stern told ThinkProgress. “When we sat down and read through the agreement, we were sort of shaking our head a little bit.” Shaking them in disbelief, perhaps, that the deal had shaken out in a way that gave the United States practically everything it wanted, from ambitious five-year review cycles and global goals to a restructuring of the requirements demanded of developed and developing nations. SolarCity Corp. confirmed funding a group that has taken actions over the past year to discredit Arizona utility regulators, often related to their decisions about solar power. The news angered regulators, including Bob Stump, who has been a target of an extensive public-records battle. The Washington, D.C.-area based Checks and Balances Project took a deep interest in Arizona Corporation Commission members early this year, filing a number of public records requests in an attempt to highlight close relationships between regulators and the companies that they regulate. New projections of permafrost change in northern Alaska suggest far-reaching effects will come sooner than expected, scientists reported this week at the fall meeting of the American Geophysical Union. "The temperature of permafrost is rapidly changing," said Vladimir Romanovsky, head of the Permafrost Laboratory at the University of Alaska Fairbanks Geophysical Institute. "For the last 30 years, the mean annual ground temperature at the top of permafrost on the North Slope has been rising," Romanovsky said. The mean annual ground temperature -- an average of all of the years' highs and lows at the Deadhorse research site -- was 17.6 degrees Fahrenheit (minus 8 degrees Celsius) in 1988, and now it's 28.5 F (minus 2 C). Researchers expect the average annual ground temperature to reach 32 F (0 C), the melting point of ice, in many areas.
News Article | December 14, 2016
SAN FRANCISCO — Though they appear to be frozen giants, glaciers and ice sheets can move and change in unexpected ways over time, according to a new database that is now tracking the movement of ice, including the extent of its melt and slow creep into the sea. With imagery and data from Landsat 8, an Earth-monitoring satellite, scientists at NASA and the U.S. Geological Survey (USGS) are tracking the speed of glaciers' movement and melt. These observations are in"near real time" and help to better predict how global sea levels will be affected by climate change, the researchers said. The so-called Global Land Ice Velocity Extraction (GoLIVE) project uses observations from Landsat 8, as well as historical data from older Landsat satellites. By comparing data from Landsat 8, which images the Earth's entire surface every 16 days, the GoLIVE team can track subtle changes in the glacier, such as bumps and dunes, the researchers said. Ted Scambos, a senior research scientist at the National Snow and Ice Data Center at the University of Colorado Boulder and the Colorado lead for the GoLIVE project, said Landsat 8 can even capture changes in a glacier's "skin." [Photo Gallery: Life Inside a Glacier] "Not only are we able to map the glacier chunks where there are large crevices and high-contrast features, but [we can] also [map] the surface of the ice sheet even where it's smooth, down to these snow-dune features," Scambos said here Monday (Dec. 12) in a news briefing at the annual meeting of the American Geophysical Union. "By being able to track with higher precision what the surface texture looks like, we can actually map the flowing skin of the ice sheet." Such observations were previously extremely difficult, if not impossible, for researchers to make. The first time scientists studied a surging glacier in detail, they did so via annual field research, said Mark Fahnestock, a professor in the Geophysical Institute at the University of Alaska Fairbanks. Scientists visited that glacier every year for 15 years, putting down stakes during each visit. They then surveyed those stakes to determine any changes in the glacier. But these very large, remote glacial systems in Alaska could experience sped-up melt events for months without scientists taking notice, Fahnestock said. "We've entered an era where instead of a pilot telling us a glacier is changing, or instead of a field party recognizing a change in one of the 242 glaciers followed, we are actually following on a month-by-month basis with Landsat 8," Fahnestock said. "We are now watching all of the outlet glaciers on Earth change in near real time." Twila Moon, a research scientist at the University of Bristol in the United Kingdom, joked that rather than researching several glaciers over hundreds of years, the GoLIVE project allows for the study of hundreds of glaciers over several years. The project could also "launch a thousand ships" in terms of international research into glaciers, Scambos said. As a public database, the project will allow for scientists around the world to conduct more effective field research, according to the GoLIVE time, because scientists will have better "situational awareness" of a given glacier before researching it in person. One other important implication, Scambos said, is that the data makes it clear that the glaciers are melting. "By presenting the data in an easy-to-understand way, it makes it obvious what's going on in the world's eyes, and that the world is changing and that there's no attempt to hide it at all," Scambos said. "It makes it plain as day that we have a changing Earth."
News Article | October 31, 2016
Based on a unique dataset collected during a research cruise to the Irminger Sea in April 2015, a new paper reveals a strong link between atmospheric forcing, deep convection, ocean ventilation and anthropogenic carbon sequestration. The Irminger Sea, a small ocean basin between Greenland and Iceland, is known for its harsh and extreme weather conditions during winter. Research cruises that take measurements in the subpolar North Atlantic almost exclusively do so in summer, although the area is particularly interesting in the convectively active winter season. Wintertime on-board ship measurements in the Irminger Sea were collected in April 2015 by scientists from the Bjerknes Centre for Climate research, as part of the SNACS project funded by the Norwegian Research Council. The results are now published in Nature Communications by Friederike Fröb, a PhD student at the Geophysical Institute of the University of Bergen and the Bjerknes Centre for Climate Research, with colleagues from the University of Bergen, Uni Research Bergen, the University of Toronto and the Bedford Institute of Oceanography, both in Canada. Compared to the far more famous Labrador Sea where deep convection is observed almost every year, convection in the Irminger Sea is more rare, and more variable in extent and strength. The 2015 data show record winter mixed layers of 1,400m depth -- usually observed are 400m. The last time winter mixing had been that deep was probably in the mid-1990s, however, there is only indirect evidence for that; no direct measurements are available from that time. In the late 2000s, during the winters 2007/08 and 2011/12, convection down to between 800m and 1,000m was observed by ARGO floats. With the newly collected data in 2015, oxygen and carbon concentrations during active convection have been determined as well. These data show that oxygen and anthropogenic CO2 concentrations were both almost saturated with respect to the atmosphere in the upper water column. This resulted in a replenishment of depleted oxygen levels at mid-depth as well as a sequestration of large amounts of anthropogenic carbon to the deep ocean. Compared to historic cruise data in 1997 and 2003 covering the same transect as the 2015 cruise, the anthropogenic carbon storage rate almost tripled in response to the large variability in the physical climate system. The main driver for that extreme convective event in 2015 was the strong heat flux from the water column, a consequence of exceptionally strong winds that developed that winter around the southern tip of Greenland. The winter 2014-2015 was also the coldest on record in the North Atlantic, a phenomenon known as the 'cold-blob'. This cold-blob has been tied to a reduced Atlantic Meridional Overturning Circulation as a consequence of increased freshwater runoff from the melting Greenland Ice Sheet and the Arctic, which increases ocean stratification. Although observations of one extreme event during winter can not be used to reject a hypothesis that is based on long-term trends, global climate model predictions are definitely challenged. The ability or lack of such to resolve small scale atmospheric phenomena like the ones in the Irminger Sea might be of greater relevance to simulate convective processes in the North Atlantic than anticipated. Overall, the cruise observations reveal the strong, direct link between atmospheric forcing, oceanic heat loss, ventilation, and anthropogenic carbon storage in the Irminger Sea. Further, the cruise data shows the necessity of ongoing, continuous data collection in remote areas also during harsh seasons, allowing to study highly variable natural processes as well as the impact of anthropogenic climate change on ocean biogeochemistry.