first_imgAs the accuracy and sensitivity of remote-sensing satellites improve, there is an increasing demand for more accurate and updated base datasets for surveying and monitoring. However, differentiating rock outcrop from snow and ice is a particular problem in Antarctica, where extensive cloud cover and widespread shaded regions lead to classification errors. The existing rock outcrop dataset has significant georeferencing issues as well as overestimation and generalisation of rock exposure areas. The most commonly used method for automated rock and snow differentiation, the normalised difference snow index (NDSI), has difficulty differentiating rock and snow in Antarctica due to misclassification of shaded pixels and is not able to differentiate illuminated rock from clouds. This study presents a new method for identifying rock exposures using Landsat 8 data. This is the first automated methodology for snow and rock differentiation that excludes areas of snow (both illuminated and shaded), clouds and liquid water whilst identifying both sunlit and shaded rock, achieving higher and more consistent accuracies than alternative data and methods such as the NDSI. The new methodology has been applied to the whole Antarctic continent (north of 82°40′ S) using Landsat 8 data to produce a new rock outcrop dataset for Antarctica. The new data (merged with existing data where Landsat 8 tiles are unavailable; most extensively south of 82°40′ S) reveal that exposed rock forms 0.18 % (21 745 km2) of the total land area of Antarctica: half of previous estimates.last_img read more

first_imgThe Victory Bell rang loud and often on Saturday night, as USC lost its third straight game to the crosstown rival UCLA Bruins and ended its Pac-12 title aspirations this season.Losing control · Redshirt junior quarterback Cody Kessler and the Trojans fell to UCLA for the third straight time on Saturday night. Kessler went 22-of-34 for 214 yards and one touchdown in a losing effort. – Ralf Cheung | Daily TrojanThe Bruins (9-2, 6-2 Pac-12) sacked redshirt junior quarterback Cody Kessler six times en route to their 38-20 win over the Trojans (7-4, 6-3) at the Rose Bowl. USC’s young offensive linemen appeared completely incapable of protecting Kessler, who finished the game with 214 yards and one touchdown and one interception.“It’s hard to get through progressions when guys are in the backfield,” Kessler said. “I tried to make some plays on the run and make some stuff happen, but they did a good job all around.”While Kessler and the Trojans struggled with execution, UCLA quarterback Brett Hundley threw for 326 yards and three touchdowns and became UCLA’s all-time leader in total offense.Hundley made one early mistake but ran the offense efficiently from there on out. On UCLA’s second offensive play of the game, Hundley forced a pass into tight coverage, and USC redshirt junior linebacker Anthony Sarao picked it off and ran in back for a 17-yard touchdown to give USC its only lead of the game.After stalling on the ensuing drive, UCLA punted to junior wideout Agholor, who fumbled the ball and allowed the Bruins to take over on the 8-yard line. UCLA made good on its nation’s-best 97.4 percent conversion rate in the red zone, and evened the score at 7-7. Agholor’s mistake shifted the momentum back toward the Bruins, and they never looked back.Agholor, who was recently named a finalist for the Biletnikoff Award, severely disappointed after posting two straight games with more than 200 receiving yards. The Tampa, Florida, native dropped one potential touchdown and finished the game with just 24 yards on three catches.USC head coach Steve Sarkisian noted that the offense couldn’t execute when Kessler forced it to Agholor.“Sometimes when you throw the ball so much to one guy — not necessarily out of design, but that’s what happened the last couple weeks — you can potentially fall into a little trap of, ‘That’s where it should always go,’” Sarkisian said. “We’ve got other really good players. We’re at our best when the ball is getting deployed to a variety of people.”The Trojans went into halftime down 24-14 following a touchdown reception by sophomore tailback Justin Davis and three Hundley touchdowns to Devin Lucien, Thomas Duarte and Eldridge Massington, but the floodgates opened as soon as the second half began. The Bruins drove 84 yards down the field, capped off by a 10-yard touchdown run by Paul Perkins, who surpassed USC redshirt junior tailback Javorius “Buck” Allen for the most rushing yards in the Pac-12.Allen, who averaged 118.4 yards per game coming into the matchup, finished with just 60 yards behind the shaky offensive line.Redshirt sophomore offensive lineman Zach Banner, who started at right tackle, felt his individual effort could have changed the course of the game.“I feel like I let my team down,” Banner said. “But, like Coach [Sarkisian] said, people make mistakes. Everybody’s gonna have mistakes. I just expect myself to be perfect.”The Trojans were far from perfect, though, converting just eight of 17 attempts on third down. UCLA wasn’t much better on third down, going just nine-for-16, but still looked dominant on both sides of the ball. Hundley, who has been hailed for his dual-threat capabilities, scampered into the end zone midway through the third quarter to give UCLA its biggest lead of the game, at 38-14.Despite being down by 24, Sarkisian said his team never let up.“I will say this: I am proud of our guys — their effort, their willingness to compete late in the game and battle,” Sarkisian said. “They came right together as a team, which is a hard thing to do through disappointment, through adversity, but again, I’ve been praising these guys for that all along.”The Trojans demonstrated their resolve late in the game by stringing together their longest drive: a 15-play, 91-yard sequence that resulted in an Allen rushing touchdown. But it was a thankless score, as a failed two-point conversion made it an 18-point game.Though it was a crushing defeat for the Trojans, Sarkisian insists the team will bounce back for its final home game of the season.“We’re not dead,” Sarkisian said. “We lost a football game.”last_img read more