Posts tagged meeting
CU Boulder research team finds massive crevasses and bendable ice affect stability of Antarctic ice shelf
Dec 7th
Gaping crevasses that penetrate upward from the bottom of the largest remaining ice shelf on the Antarctic Peninsula make it more susceptible to collapse, according to University of Colorado Boulder researchers who spent the last four Southern Hemisphere summers studying the massive floating sheet of ice that covers an area twice the size of Massachusetts.
But the scientists also found that ribbons running through the Larsen C Ice Shelf – made up of a mixture of ice types that, together, are more prone to bending than breaking – make the shelf more resilient than it otherwise would be.
The research team from CU-Boulder’s Cooperative Institute for Research in the Environmental Sciences presented the findings Dec. 6 at the American Geophysical Union’s annual meeting in San Francisco.
The Larsen C Ice Shelf is all that’s left of a series of ice shelves that once clung to the eastern edge of the Antarctic Peninsula and stretched into the Weddell Sea. When the other shelves disintegrated abruptly – including Larsen A in January 1995 and Larsen B in February 2002 – scientists were surprised by the speed of the breakup.
Researchers now believe that the catastrophic collapses of Larsen A and B were caused, at least in part, by rising temperatures in the region, where warming is increasing at six times the global average. The Antarctic Peninsula warmed 4.5 degrees Fahrenheit since the middle of the last century.
The warmer climate increased meltwater production, allowing more liquid to pool on top of the ice shelves. The water then drained into surface crevasses, wedging them open and cracking the shelf into individual icebergs, which resulted in rapid disintegration.
But while the meltwater may have been responsible for dealing the final blow to the shelves, researchers did not have the opportunity to study how the structure of the Larsen A and B shelves may have made them more vulnerable to drastic breakups – or protected the shelves from an even earlier demise.
CU-Boulder researchers did not want to miss the same opportunity on the Larsen C shelf, which covers more than 22,000 square miles of sea.
“It’s the perfect natural laboratory,” said Daniel McGrath, a doctoral student in the Department of Geography and part of the CIRES research team. “We wanted to study this shelf while it’s still stable in order to get a better understanding of the processes that affect ice shelf stability.”
McGrath worked with CIRES colleagues over the last four years to study the Larsen C shelf in order to better understand how the warming climate may have interacted with the shelf’s existing structure to increase its vulnerability to a catastrophic collapse.
McGrath presented two of the group’s key findings at the AGU meeting. The first was the role that long-existing crevasses that start at the base of the shelf and propagate upward – known as basal crevasses – play in making the shelf more vulnerable to disintegration. The second relates to the way a type of ice found in areas called suture zones may be protecting the shelf against a breakup.
The scientists used ground penetrating radar to map out the basal crevasses, which turn out to be massive. The yawning cracks can run for several miles in length and can penetrate upwards for more than 750 feet. While the basal crevasses have been a part of Larsen C for hundreds of years, the interaction between these features and a warming climate will likely make the shelf more susceptible to future disintegration. “They likely play a really important role in ice-shelf disintegration, both past and future,” McGrath said.
The research team also studied the impact of suture zones in the ice shelf. Larsen C is fed by 12 distinct glaciers, which dump a steady flow of thick ice into the shelf. But the promontories of land between the glacial outlets, where ice does not flow into the shelf, allow for the creation of ribbon-like suture zones, which knit the glacial inflows together and which turn out to be important to the ice shelf’s resilience. “The ice in these zones really holds the neighboring inflows together,” McGrath said.
The suture zones get their malleable characteristic from a combination of ice types. A key component of the suture zone mixture is formed when the bottoms of the 12 glacial inflows begin to melt. The resulting freshwater is more buoyant than the surrounding seawater, so it rises upward to the relatively thinner ice zones between the glacial inflows, where it refreezes on the underside of the shelf and contributes to the chaotic ice structure that makes suture zones more flexible than the surrounding ice.
It turns out that the resilient characteristics of the suture zones keep cracks, including the basal crevasses, from spreading across the ice shelf, even where the suture zone ice makes up a comparatively small amount of the total thickness of the shelf. The CIRES team found that at the shelf front, where the ice meets the open sea, suture zone ice constitutes only 20 percent of the total thickness of the shelf but was still able to limit the spread of rifts through the ice. “It’s a pretty small part of the total ice thickness, and yet, it still has this really important role of holding the ice shelf together,” McGrath said.
Other CU researchers involved in the Larsen C project were Konrad Steffen, former director of CIRES; Ted Scambos, of CIRES and CU-Boulder’s National Snow and Ice Data Center; Harihar Rajaram, of the Department of Civil Engineering; and Waleed Abdalati, of CIRES.
Boulder Walker Ranch Management
Nov 8th
Boulder County, Colo. – The Boulder County Parks and Open Space Department will host a review of the Management Alternatives proposed by Parks and Open Space staff for the Walker Ranch Management Plan Update.
What: Walker Ranch Management Alternatives meeting
When: Tuesday, Nov. 13 at 6 p.m.
Where: Boulder County Transportation office, second floor 2525 13th St., Boulder
Staff will give a presentation of the management proposals followed by a question-and-answer period.
Ideas received at a public open house in 2011 have been incorporated into the proposals. Staff will present those proposals at this meeting and take public comments and questions. This will not be the last opportunity for public input.
Based on public responses to the alternatives and information gathered during alternatives review, staff will develop and update the plan and present a draft final management plan to the public in December. A 30-day comment period will follow the December presentation. The final proposal to the Parks and Open Space Advisory Committee and the Board of County Commissioners will be scheduled in early 2013.
For more information about the Walker Ranch Management Plan Update, visit www.bouldercounty.org/os/openspace/pages/walkerplan.aspx or contact Resource Planner Jesse Rounds at 303-678-6271 or jrounds@bouldercounty.org.
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CU Buff sports (not so) briefs
Sep 28th
Buffs Return To Prentup For Pac-12 Play
QUICKLY: The CU soccer team begins its home Pac-12 Conference schedule at Prentup Field this weekend. The Buffs are unbeaten through four games, losing only once so far this season. CU (6-1-3) takes on Washington and Wash ington State to begin a five-game homestand. The Buffs open against the 7-2-1 Huskies on Friday at 3 p.m. The weekend ends on Sunday as the Buffs take on the Cougars (6-2-1) at 2:30 p.m. Be sure to stick around after Sunday’s game for a special autograph session with the team!
COLORADO VS. WASHINGTON: This will be just the second meeting for the Buffs and Huskies. In their first season in the Pac-12, the Buffs fell 2-1 at Husky Soccer Complex. Anne Stuller scored an unassisted goal to put CU on the board in last year’s defeat.SCOUTING THE HUSKIES: The Huskies have lost two straight. They fell 3-1 to then-ranked No. 17 BYU and were upset by USC in their conference opener. Junior Lindsay Elston, who has six goals and four assists, is one of eight Huskies to score this season. Goalkeeper Kari Davidson leads the Pac-12 in saves.
COLORADO VS. WASHINGTON STATE: This will be the third time the Buffs and Cougars have met. In their first meeting in 2010, CU claimed a 2-1 overtime win. Last season, the Buffs fell 4-0 at Lowe Soccer Field in Pullman, Wash.
SCOUTING THE COUGARS: The Cougars shut out then-ranked No. 2 UCLA last Friday in a scoreless tie, but fell to Santa Clara on Sunday. In their two losses, the Cougars have been blanked 7-0. WSU is an offensive presence, scoring 21 goals this season, including eight by Micaela Castain.
LAST WEEK: CU opened Pac-12 Conference play last Friday at Oregon. Both teams went into the match-up un beaten through their previous three games, and a scoreless double overtime tie extended their streaks. CU goalkeeper Annie Brunner had four saves in her third straight shutout. BUFF BRIGADE: CU fans help give the Buffs a real home field advantage at Prentup. Colorado ranks third in the Pac-12 in attendance, averaging 1,117 fans per game. The Buffs are undefeated in three home games this season.
CU KNOWS NO DEFEAT: CU is currently on a four-game unbeaten streak. The Buffs have shut out their three previous opponents, and six total. CU goalkeeper Annie Brunner leads the Pac-12 in shutouts and is in a four-way tie for third on CU’s single season shutouts list.
WINNING: The Buffs began the 2012 season with an unprecidented five-game unbeaten streak, including three straight shutouts in their opening games, both program firsts. CU has only lost once this season, 4-1 to Denver at the DU
Invitational. The 6-1-2 non-conference start marks just the the fifth time in program history that CU won at least six regular-season non-conference games. The most recent was a 7-1-1 start in 2008.
COLORADO CONNECTIONS: Washington and Washington State have a combined four players from Colorado. UW’s Berkley Gamble and CU’s Anne Stuller and Nikola Machalek are all Boulder natives who attended Fairview. WSU freshman Susie White attended Mountain Vista in Highlands Ranch, as did CU junior Hayley Hughes. Mesa Owsley and Kourtney Guetlein of WSU are from Fort Collins and Monument, respectively.
RECORD BREAKERS: Juniors Annie Brunner and Anne Stuller continue to make their names known in Pac-12 soccer. Brunner leads the Pac-12 with six shutouts and is tied for third with 34 saves this season. She is in a four-way tie for third on CU’s single season shutouts list, and with 13 shutouts in her career, holds down the third spot for most all-time by a Buff. It took Stuller just 106 shots (landing her in a three-way tie on CU’s career list) to also break into CU’s top 10 for shots on goal. She ties Gianna DeSaverio (2007-08) with 50 shots on goal. With seven goals this season, Stuller ties Melissa Cartmell (1999) for fifth on CU’s list of most goals by a junior.
ALL-STAR ATHLETES: Three Buffs have received major honors this season.
Sept. 10-16: Annie Brunner, CU Athlete of the Week
vs. Wyoming W 2-0 0 goals allowed 4 saves
vs. Air Force W 2-0 0 goals allowed 4 saves
Brunner has recorded 131 saves all-time, moving past Kara Linder (2006-09) for sixth most for the Buffs. She notched back-to-back shutouts to hold down the sixth spot twice with five shutouts in two different seasons (2010 was her first).
Aug. 27-Sept. 2: Madison Krauser, CU Athlete of the Week
vs. Northwestern T 2-2 3 shots 1 goal 2 points
Krauser’s first goal of the season came just minutes after captain Amy Barczuk scored in the second half. She is the only freshman to have started every game.
Aug. 20-27: Anne Stuller, Pac-12 Conference Offensive Player of the Week, CU Athlete of the Week, Soccer America Women’s Team of the Week
vs. LIU W 2-0 6 shots 2 goals 4 points
vs. Wright State W 2-1 5 shots 2 goals 4 points
Stuller joined Nikki Marshall (2006) and Katie Griffin (2005) to become only the third player in CU history to have three multiple goal games in a single season, with her other two-goal game happening at Northern Colorado.
Aug. 13-19: Annie Brunner, Pac-12 Conference Defensive Player of the Week
vs. Northern Colorado W 3-0 0 goals allowed 3 saves
vs. Colorado College T 0-0 0 goals allowed 5 saves
Brunner shut out both teams in the Colorado Cup and also shut out LIU in the Omni Hotels Colorado Women’s Soccer Classic. It was the first time in CU history the Buffs started their season with three shutouts and the first time since 2008 the team had three shutouts in a row.
Anne Stuller, CU Athlete of the Week
vs. Northern Colorado W 3-0 3 shots 2 goals 4 points
vs. Colorado College T 0-0 2 shots
PAC-12 COACHES POLL: Colorado was picked to finish 11th in this year’s Pac-12 Coaches Poll. Stanford, the reigning NCAA Champion, received nine out of 11 possible first-place votes. UCLA, Cal, Oregon State and Washington rounded out the top five. Arizona State and USC followed, with Utah and Washington State tied for eighth. Oregon and Arizona were chosen as 10th and 12th.
COMING UP: Remember the Buffs are also at home next weekend with two big conference matchups. On Friday, Oct. 5, the Buffs take on California at 4 p.m. Crocs will be hosting a shoe donation drop box at the game in conjunction with their Crocs Cares program. The first 100 fans who donate a pair of shoes will receive a $50 Crocs gift card! CU Soccer will play No. 2 Stanford on Sunday, Oct. 7 at 1 p.m. Make sure to arrive early for a special pregame appearance and run by Ralphie!
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