Thursday, December 9, 2010
Scripps News at 2010 AGU Fall Meeting
Scripps Institution of Oceanography / University of California, San DiegoDroughts in the West
H12D-04 · Monday, Dec. 13, 11:05 a.m. · 3020 Moscone West
As the climate warms over the next several decades, the southwest U.S. could experience more severe dry spells according to a new climate study from a Scripps Institution of Oceanography at UC San Diego research team.
Scripps scientist Dan Cayan and colleagues will present results from a study that investigated climate change effects on the hydrology of the southwest. The climate model study showed more intense and prolonged drought events for the U.S. southwest by the second half of the 21st century. The study exposes the risk of sustaining water supplies as snowpack disappears and soil dries in response to global warming.
The study reinforces previous investigations of climate-induced dryness in the 21st century to suggest that drought symptoms may be stronger in the interior southwest than in California. The researchers used improved hydrological characteristics of future dryness than previous drought projections studies have used in the past.
PRESENTATION TITLE: "FUTURE DRY SPELLS IN THE SOUTHWEST US AGGRAVATED BY CLIMATE WARMING"
NH13A-1142 · Monday, Dec. 13, 1:40 - 6:00 p.m. · Poster Hall, Moscone South
Researchers at Scripps Institution of Oceanography at UC San Diego used seismic data to compare two equally powerful hurricanes - Katrina and Ioke. The study reveals striking differences in how energy is dispersed from hurricanes and offers a new source of information to help understand how tropical storms spend their energy.
Using ocean bottom seismometer (OBS) sites in the Pacific, set up as part of the Hawaiian PLUME project, Scripps scientists Shi Sim and Gabi Laske analyzed the seismic signature of super typhoon Ioke, a category-five storm that made landfall over the Wake Islands on Aug. 31, 2006. Ioke was the strongest hurricane ever recorded in the Central Pacific. The study compared Ioke's seismic signature with data collected nearly one year earlier in the Atlantic as Hurricane Katrina made landfall in Louisiana.
Hurricane Katrina as it approaches landfall near New Orleans on August 26, 2010. Photo: NOAA
The team will present results that show that Katrina's seismic energy peaked as it made landfall as compared to hurricane Ioke, which built up as it developed in the open ocean and peaked long before making landfall. The researchers suggest that differences in ocean floor shape and the proximity to large landmasses, as well as the interference of hurricane-generated ocean waves, may have contributed to the storms' unique seismic signatures.
PRESENTATION TITLE: "COMPARISON OF THE MICROSEISMIC SIGNATURE OF HURRICANES KATRINA (2005) AND IOKE (2006)"
T14B-07 · Monday, Dec. 13, 5:30 p.m. · 2020 Moscone West
The slow creeping motion of seismic faults could hold the key to predicting earthquake patterns, according to a new study by Scripps Institution of Oceanography at UC San Diego postdoctoral scholar Yoshihiro Kaneko and colleagues at California Institute of Technology.
Kaneko will discuss a new earthquake simulation model developed by the research team that produced scenarios of earthquake rupture patterns and showed how a creeping section impedes rupturing and is often a permanent barrier to large earthquakes.
Many faults around the world, including California's most famous seismic landmark, the San Andreas Fault, have locked regions and sections that slowly and continuously creep. The plates at the central portion of the San Andreas Fault, from San Juan Bautista to Parkfield, Calif., are gradually moving past each other three centimeters per year and produce only minor quakes. The north and south sections are firmly locked in place and release stress in the form of large earthquakes.
Kaneko simulation shows an earthquake rupture pattern as it passes through a 'creeping' fault section.
In one of the simulations, an earthquake ruptures through both the two locked segments and a central creeping patch. A subsequent earthquake at the same site 29 years later starts at the same location but is stopped by the central creeping patch.
"This simulation illustrates that the central creeping patch creates a complexity for large earthquakes in the model, acting as an occasional barrier to earthquakes and causing clustering of large events," said Kaneko.
PRESENTATION TITLE: "TOWARDS INFERRING EARTHQUAKE PATTERNS FROM GEODETIC OBSERVATIONS OF INTERSEISMIC COUPLING"
Deep Carbon Cycle
U21A-0005 · Tuesday, Dec. 14, 8:00 a.m. - 12:20 p.m. · Poster Hall, Moscone South
An unknown amount of carbon is trapped inside Earth and is occasionally released as CO2 by erupting volcanoes. By unlocking this mystery of the deep, scientists hope to understand the planet's global carbon cycle from surface to core.
Scripps Institution of Oceanography at UC San Diego professor of geochemistry David Hilton will present results from isotope analysis of geothermal fluids collected in submarine seeps in Costa Rica and throughout Central America.
Using data derived from CO2 and helium isotopes, Hilton analyzes the earth's deep carbon budget. The study compares the carbon input from the Cocos tectonic plate, which is subducting into the earth's mantle beneath the Pacific Ocean, and the carbon output from volcanoes in Central America and submarine seeps along the seafloor.
Scripps researchers descend Costa Rica's Poas volcano to collect water and fluid samples.
Subduction zones, such as the Central America convergent margin, where tectonic plates collide and slip back inside Earth, provide an important pathway for input of carbon from Earth's external reservoirs - crust, sediments, oceans - to the mantle. This along with outputs from volcanoes comprises the deep carbon cycle.
"A significant amount of carbon is locked away in minerals in Earth's mantle and core," said Hilton.
Scientists are working to estimate crust- and mantle-derived and deep microbial carbon sources and sinks in order to better understand how they are linked to terrestrial carbon reservoirs and contribute to the global carbon cycle.
PRESENTATION TITLE: "TOWARDS UNDERSTANDING CARBON RECYCLING AT SUBDUCTION ZONES - LESSONS FROM CENTRAL AMERICA"
A32A-03 · Wednesday, Dec. 15, 10:50 a.m. · 3002 Moscone West
Recent climate studies have shown a widening of the tropics during the past several decades results in a poleward shift of the jet stream and storm tracks. Joel Norris of Scripps Institution of Oceanography at UC San Diego is using data from observational research studies and climate models to determine if a corresponding shift in storm track cloudiness occurs.
Norris will discuss how this shift of strongly reflective clouds to higher latitudes could amplify man-made global warming by causing more solar radiation to be absorbed by the climate system.
Clouds in the tropical Pacific. Photo: NASA
The role of clouds in climate change has been a major question for decades. As the earth warms under increasing greenhouse gases, it is not known whether clouds will dissipate, letting in more of the sun's heat energy and making the earth warm even faster, or whether cloud cover will increase, blocking the sun's rays and actually slowing down global warming.
Norris compared the observed changes with those produced by 20th Century climate model simulations and found that the observed changes were larger than what most models predicted.
PRESENTATION TITLE: "OBSERVED LATITUDINAL SHIFT IN STORM TRACK CLOUDINESS DURING RECENT DECADES"
U34A-02 · Wednesday, Dec. 15, 4:30 p.m. · 104 Moscone South
Helen Amanda Fricker, associate professor at Scripps Institution of Oceanography at UC San Diego, will discuss NASA's Ice, Cloud, and land Elevation (ICESat) satellite mission, which recently completed a nearly seven-year scientific mission that began in 2003. The laser altimeter affixed to the ICESat satellite acquired surface elevations along repeated ground tracks providing scientists with a new tool to study ice sheet processes.
One of ICESat's most significant and unexpected discoveries was related to Antarctica's subglacial hydrology. In the Feb. 15, 2007 issue of the journal Science, Fricker and co-authors detailed a previously unknown region of subglacial lakes lying under two fast-flowing ice streams about one kilometer (3,280 feet) thick ice sheet. The study provided the first evidence that subglacial water is stored in a linked system of reservoirs underneath the ice and can move quickly into and out of those reservoirs.
A subglacial lake in the western Antarctic detected by ICESat.
The findings were made by precise repeated elevation measurements acquired by ICESat from 2003 to 2006 collected over the Whillans and Mercer ice streams in West Antarctica. The two ice streams are major feeders of ice to the Ross Ice Shelf, Antarctica's largest ice shelf covering an area of the ocean about the size of France with ice several hundred meters thick.
PRESENTATION TITLE: "ICESAT'S CONTRIBUTION TO ADVANCING OUR UNDERSTANDING OF ICE SHEET PROCESSES" (Invited)
C43A-0519 · Thursday, Dec. 16, 1:40 - 6:00 p.m. · Poster Hall, Moscone South
A panoramic view of Alpine glaciers in Gornergletscher, Switzerland. Photo: Simo Räsänen
Scientists are using seismometers to record icequake activity near glacier-dammed lakes in an effort to determine the connection between increased icequake activity and lake drainage events.
Debi Kilb, a seismologist at Scripps Institution of Oceanography at UC San Diego, will discuss their findings from over 100,000 icequakes, events similar to earthquakes but in ice, that were recorded by seismometers installed at the glacier surface during three summers in Gornergletscher, Switzerland. The researchers recorded up to several thousand icequakes per day during each field season.
Scientists are interested in understanding whether icequakes yield a unique signal indicating when lake drainage will occur. Understanding interactions between lakes and quakes is important since these natural lake drainage events are difficult to predict and often pose a serious threat to human life and infrastructure near glaciated regions.
The study showed a significant increase in icequake productivity coincident during lake drainage events during two of the three seasons studied. However, the seismic data analysis did not reveal a warning signal that an upcoming drainage will occur.
PRESENTATION TITLE: "SPATIAL AND TEMPORAL ASPECTS OF ALPINE ICEQUAKES DURING THREE SEASONS OF GLACIER-DAMMED LAKE DRAINAGES: GORNERGLETSCHER, SWITZERLAND"
Beach Pollutant Study
OS51B-1306 · Friday, Dec. 17, 8:00 a.m. - 12:20 p.m. · Poster Hall, Moscone South OS53D-03 · Friday, Dec. 17, 2:10 p.m. · 3007 Moscone West
Scripps Institution of Oceanography at UC San Diego researchers Falk Feddersen, David Clark and Bob Guza have created new tools to estimate the transport and dilution of surf zone pollutants. The Scripps scientists will discuss results from the month-long 2006 Huntington Beach Nearshore experiment, or HB06, in a two-part oral and poster presentation.
Using buoys, moorings, a novel high-tech jet ski and non-toxic dye tracers, the researchers monitored dye plumes to better understand the physical processes involved in the transport and mixing in the surf zone. The study's results, which will be published in an upcoming issue of AGU's Journal of Geophysical Research, can help inform decisions on when and where to close beaches.
A GPS-equipped Jet Ski was used during the 2006 Huntington Beach Nearshore Experiment.
The new technique combines the regional wave network developed by Scripps' Coastal Data Information Program (CDIP) to provide predictions of offshore waves with a model describing how waves break across the surf zone and create currents that move surfzone pollutants.
The scientists are hoping to provide a more complete picture of how pollution moves and mixes in three dimensions: along the coast, offshore and vertically. This information is important to improve water quality forecasts and minimize beachgoers' exposure to health risks.
PRESENTATION TITLES: "BOUSSINESQ MODELING OF HB06 TRACER RELEASES PART 1: WAVE AND CURRENT MODEL-DATA" AND "COMPARISONS BOUSSINESQ MODELING OF HB06 TRACER RELEASES PART 2: TRACER PLUMES"
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Scripps Institution of Oceanography, at University of California, San Diego, is one of the oldest, largest and most important centers for global science research and education in the world. Now in its second century of discovery, the scientific scope of the institution has grown to include biological, physical, chemical, geological, geophysical and atmospheric studies of the earth as a system. Hundreds of research programs covering a wide range of scientific areas are under way today in 65 countries. The institution has a staff of about 1,300, and annual expenditures of approximately $155 million from federal, state and private sources. Scripps operates one of the largest U.S. academic fleets with four oceanographic research ships and one research platform for worldwide exploration.
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