Anthony Lane
University of Maryland, Baltimore County (UMBC)
410-455-5793
alane@umbc.edu

Patrick Lynch
NASA Goddard Space Flight Center, Greenbelt, Md.
757-897-2047
patrick.lynch@nasa.gov

Katherine Leitzell
National Snow and Ice Data Center, Boulder, Colo.
University of Colorado
303-492-1497
leitzell@nsidc.org

GREENBELT, Md. -- An international team of researchers has combined data from multiple sources to provide the clearest account yet of how much glacial ice surges into the sea following the collapse of Antarctic ice shelves.

The work by researchers at the University of Maryland, Baltimore County (UMBC), the Laboratoire d'Etudes en Géophysique et Océanographie Spatiales, Centre National de la Recherche Scientifique at the University of Toulouse, France, and the University of Colorado's National Snow and Ice Data Center, Boulder, Colo. details recent ice losses while promising to sharpen future predictions of further ice loss and sea level rise likely to result from ongoing changes along the Antarctic Peninsula.

"Not only do you get an initial loss of glacial ice when adjacent ice shelves collapse, but you get continued ice losses for many years — even decades — to come," says Christopher Shuman, a researcher at UMBC's Joint Center for Earth Systems Technology (JCET) at the NASA Goddard Space Flight Center, Greenbelt, Md. "This further demonstrates how important ice shelves are to Antarctic glaciers."

Shuman is lead author of the study “2001–2009 elevation and mass losses in the Larsen A and B embayments, Antarctic Peninsula“ published online today in the Journal of Glaciology.

An ice shelf is a thick floating tongue of ice, fed by a tributary glacier, extending into the sea off a land mass. Previous research showed that the recent collapse of several ice shelves in Antarctica led to acceleration of the glaciers that feed into them. Combining satellite data from NASA and the French space agency CNES, along with measurements collected during aircraft missions similar to ongoing NASA IceBridge flights, Shuman, Etienne Berthier of the University of Toulouse and Ted Scambos of the University of Colorado produced detailed ice loss maps from 2001 to 2009 for the main tributary glaciers of the Larsen A and B ice shelves, which collapsed in 1995 and 2002, respectively.

"The approach we took drew on the strengths of each data source to produce the most complete picture yet of how these glaciers are changing," Berthier said, noting that the study relied on easy access to remote sensing information provided by NASA and CNES. The team used data from NASA sources including the MODerate Imaging Spectroradiometer (MODIS) instruments and the Ice, Cloud and land Elevation Satellite (ICESat).

The analysis reveals rapid elevation decreases of more than 500 feet for some glaciers, and it puts the total ice loss from 2001 to 2006 squarely between the widely varying and less certain estimates produced using an approach that relies on assumptions about a glacier's mass budget.

The authors’ analysis shows ice loss in the study area of at least 11.2 gigatons per year from 2001 to 2006. Their ongoing work shows ice loss from 2006 to 2010 was almost as large, averaging 10.2 gigatons per year.

“This study shows where the tracking of sea level rise is heading in terms of the level of detail possible and the instrumentation that can be brought to bear,” Scambos said. “We’re showing that glacier changes can start fast, with a single climate or ocean ‘bang’, but they have a long persistence.”

An animation showing ice edge changes for the Larsen B ice shelf and its adjacent tributary glaciers is available online, along with a larger version of the map below showing elevation changes of tributary glaciers.

A companion paper — “The triggering of sub glacial lake drainage during rapid glacier drawdown: Crane Glacier, Antarctic Peninsula” — by the same three authors, led by Scambos, is also available online in the Annals of Glaciology in the issue “Earth's Disappearing Ice: Drivers, Responses and Impacts.”

MS thesis defense

A Fast Fullchip Transient Response Estimation Technique

Sushmita K. Rao

11:00am Monday, 25 July 2011, ITE 346

Circuit Simulation has long been a dependable technique for design engineers for functional testing before a circuit is taken to silicon. But as we move into very deep sub-micron technologies, chips are becoming more complex and denser. The dense power grid adds to long simulation run time rendering fullchip simulations difficult and computationally expensive for larger designs. Some large designs may not be simulatable owing to system requirements. Even fast simulators like Cadence UltraSim fail to provide SPICE level accuracy. Dynamic solutions provide greater accuracy than statistical techniques but long simulation run time becomes the biggest tradeoff. Accurate measurement of dynamic currents is required for applications like power estimation, supply noise predictions and in verifying the power grid designs and testing. The research reported in this thesis is focussed on providing a current based method to estimate a fullchip's transient response without carrying out a fullchip simulation. Instead, a part of the chip is simulated and the power port currents thus measured are used to estimate the fullchip currents using the principle of superposition. This technique eliminates fullchip simulations that are complex and time consuming but the accuracy is maintained as the fullchip estimation is carried out on simulated data. A simple scaling method is also proposed to compensate for resistive variations in the test circuits. Experimental results reported demonstrate the effectiveness of the method.

Committee members:

• Dr. Chintan Patel (Chair)
• Dr. Ryan Robucci
• Dr. Tinoosh Mohsenin

Dr. Penny Rheingans, professor of computer science and electrical engineering, co-directs UMBC's VAnGOGH lab, where she uses her knowledge in data visualization to solve problems in a variety of application areas. “I think it’s a really cool area because it allows me to synthesize things from a number of areas,” says Rheingans of the field, which allows her to combine techniques from computer graphics, art and illustration, and knowledge of human perceptual and cognitive systems.

To read more about Dr. Rheingans' research pursuits, see her full research profile.

Dr. Tinoosh Mohsenin, professor of computer science and electrical engeineering, runs UMBC's Engergy Efficient High Performance Computing Lab, where she works to develop highly accurate, low-power communications and healthcare devices. Currently, Dr. Mohsenin is pursuing three distinct projects in conjunction with her lab that fall within the realm of digital signal processing (DSP) and VLSI implementation: 1) many-core architectures for DSP and secured trusted platforms, 2) low-power processors for portable healthcare devices, and 3)efficient error correction techniques for communication devices.

To read more about Dr. Mohsenin's research pursuits, see her full research profile.

Dr. Fow-Sen Choa, professor of computer science and electrical engineering, uses a Chemical Vapor Desposition System to grow semiconductors that are used for chemical detection and breath analysis using photo-acoustic (PA) effects. In addition, he has been working with undergraduate students at UMBC on projects dealing with flying robots, Fourier analysis of music instrument, x-ray scan of superlattice crystal growths, and brainwave measurement and analysis.

To read more about Dr. Choa's research pursuits, see his full research profile.

Photo courtesy of the New York Times.

Same sex marriage has historically been a political flash-point in the U.S.

That flash-point just got a little flashier this weekend when hundreds of couples joined in wedded bliss as New York became the sixth and largest U.S. state to recognize same sex marriages.

New York now joins Iowa, Vermont, New Hampshire, Massachusetts and Connecticut in recognizing same-sex unions.

The day was emotionally charged for many. Couples waited in the stifling July heat, and volunteers passed out water bottles. Steve Mulrooney and Jerome Van Wert traveled all the way from Missouri to be married.

Kitty Lambert and Cheryl Rudd were married at Luna Island immediately after midnight, making them the state’s first same-sex union. Ms. Lambert said,

“We’re achieving that real American dream to be treated like everybody else and be protected under all those laws.”

Others were less enthusiastic about the change. Rallies in New York, Albany, Buffalo, and Rochester drew crowds opposed to the change.

Crowds waved signs reading, “Marriage=Man and Woman,” and, “God Cannot Be Mocked.” Tre’ Staton, an organizer of the protest explained,

“We’re not against anybody, but we don’t want this imposed on us…We’re looking for a referendum, an opportunity to have our fair say.”

With the upcoming repeal of the Don’t Ask Don’t Tell policy, tempers, along with temperatures, seem likely to continue to climb.