Month: May 2021

  • The ionospheric response to flux transfer events: the first few minutes

    first_imgWe utilise high-time resolution measurements from the PACE HF radar at Halley, Antarctica to explore the evolution of the ionospheric response during the first few minutes after enhanced reconnection occurs at the magnetopause. We show that the plasma velocity increases associated with flux transfer events (FTEs) occur first ∼100–200 km equatorward of the region to which magnetosheath (cusp) precipitation maps to the ionosphere. We suggest that these velocity variations start near the ionospheric footprint of the boundary between open and closed magnetic field lines. We show that these velocity variations have rise times ∼100 s and fall times of ∼10 s. When these velocity transients reach the latitude of the cusp precipitation, sometimes the equatorward boundary of the precipitation begins to move equatorward, the expected and previously reported ionospheric signature of enhanced reconnection. A hypothesis is proposed to explain the velocity variations. It involves the rapid outflow of magnetospheric electrons into the magnetosheath along the most recently reconnected field lines. Several predictions are made arising from the proposed explanation which could be tested with ground-based and space-based observations.last_img read more

  • Vertical migration strategies with respect to advection and stratification in a semi-enclosed lough: a comparison of mero- and holozooplankton

    first_imgPatterns of zooplankton vertical movement are often difficult to interpret because of multiple, complex and confounding environmental factors. Behavioural adaptations to these environmental variables are compared within and between the holo- and meroplankton constituents of a community. We used a nested design to analyse patterns at several scales in time; (semi-diel, diel, spring-neap tidal cycle and season) and two in space; (depth and site). To reduce complexity and aid interpretation we studied a semi-isolated community in a semi-enclosed, seasonally stratified sea lough (Lough Hyne Marine Nature Reserve, Ireland). In this, the main environmental gradient was water flow rate (or water residence time) caused by tidal currents. Vertical profiles of abundance showed that populations of the most abundant species of holo- and meroplankton in the lough have considerable behavioural plasticity, enabling them to switch between sedentary and migratory behaviour and patterns of migration. Some species migrate vertically in synchrony with diel cycles and others in response to semi-diel tidal currents; a few do both, but the majority did neither. It is suggested that water column structure and hydrographic discontinuities caused by flow rate and pycnocline dynamics are responsible for the variable patterns of vertical migration and distribution.last_img read more

  • Overlap of Karoo and Ferrar magma types in KwaZulu-Natal, South Africa

    first_imgA suite of mafic dykes from the Underberg region of southern KwaZulu-Natal (South Africa) were intruded at 178 Ma, coincident in age with the major Okavango Dyke Swarm of Botswana, and also coincident with minor Karoo-related intrusions of the northern and central Lebombo. The dykes are all low-Ti-Zr tholeiites, they trend NW-SE and are presumed to continue into the Karoo central area of the Lesotho Highlands. In many respects, the Underberg dykes are similar to the majority of the low-Ti-Zr volcanic and subvolcanic intrusions of the Karoo; however, their 87Sr/86Sr and Nd isotope ratios are either ‘Ferrar-like’ (87Sr/86Sr 0·710; Nd < -3) or transitional between Karoo low-Ti-Zr and Ferrar low-Ti magmas. A potential Ferrar source for at least some of the Underberg dykes is supported by anisotropy of magnetic susceptibility analyses of the dyke suite, which demonstrate absolute flow direction from the SE to the NW, consistent with Gondwana reconstructions. The role of crustal contamination and combined fractional crystallization is also demonstrated to have played a key role in the petrogenesis of the Underberg dykes, involving a local upper crust contaminant. However, the composition of the ‘Ferrar-like’ dykes cannot be easily explained by AFC processes, but they do demonstrate that melting of a lithospheric mantle source enriched to a small degree by subduction-derived fluid was also important.last_img read more

  • Drake Passage and Cenozoic climate: An open and shut case?

    first_imgDrake Passage opening has often been viewed as a single, discrete event, possibly associated with abrupt changes in global circulation and climate at or near the Eocene-Oligocene boundary. A new plate tectonic model, based on recent reinterpretations of the opening history of basins in the Scotia Sea, suggests that an effective ocean gateway may have developed even earlier, during the middle Eocene. This is consistent with a growing body of evidence from sediment core proxy data for Eocene changes in Southern Ocean circulation and biological productivity. The period between earliest opening after ∼50 Ma and the latest Eocene was characterized by the evolution of various current pathways across the subsiding continental shelves and intervening deep basins. This shallow opening may have caused important changes in Southern Ocean circulation, contributing to Eocene cooling and the growth of Antarctic ice sheets.last_img read more

  • Feedbacks on climate in the Earth system: introduction

    first_imgIn the last century, the Earth has undergone a very fast and unusual change in the radiative forcing of its climate, resulting from human actions. This change in forcing has resulted not only mainly from rising concentrations of greenhouse gases, particularly carbon dioxide (CO2), but also from changes in the nature of the land surface and changes in the concentrations of aerosol particles in the atmosphere and of ozone-destroying chemicals in the stratosphere. If the changes in forcing continue on their current trajectory, then very substantial changes in climate are predicted by the end of the centurylast_img

  • Multi-spectral and multi-instrument observation of TIDs following the Total Solar Eclipse of August 21, 2017

    first_imgWave‐like structures in the upper atmospheric nightglow brightness were observed on the night of 22 August 2017, approximately 8 hr following a total solar eclipse. These wave‐like perturbations are signatures of atmospheric gravity waves and associated traveling ionospheric disturbances (TIDs). Observations were made in the red line (OI 630.0 nm) and the green line (OI 557.7 nm) from Carbondale, IL, at 2–10 UTC on 22 August 2017. Based on wavelet analyses, the dominant time period in both the red and green lines was around 1.5 hr. Differential total electron content data obtained from Global Positioning System total electron content measurements at Carbondale, IL, and ionospheric parameters from digisonde measurements at Idaho National Laboratory and Millstone Hill showed a similar dominant time period. Based on these observations and their correlation with geomagnetic indices, the TIDs appear to be associated with geomagnetic disturbances. In addition, by modeling the ionosphere‐thermosphere system’s response to the eclipse, it was seen that while the eclipse enhanced the O/N2 ratio and electron density (Ne) at 250 km during our observation period, it did not affect the TIDs. Vertical (7 m/s) and meridional (616 m/s) phase velocities of the TIDs were estimated using cross‐correlation analysis between red and green line brightness profiles and spectral analysis of the differential total electron content keogram, respectively. This provides a method to characterize the three‐dimensional wave properties of TIDs.last_img read more

  • David Ragland Joins USU Men’s Basketball Coaching Staff

    first_img Tags: Bowling Green Falcons/Craig Smith/David Ragland/Franklin Phiillips CC Plainsmen/Indiana State Sycamores/Northern Kentucky Norse/Richaun Holmes/Southern Indiana Screaming Eagles/USU Men’s Basketball/Valparaiso Crusaders/Vicennes Trailblazers Written by Brad James June 25, 2018 /Sports News – Local David Ragland Joins USU Men’s Basketball Coaching Staff FacebookTwitterLinkedInEmailLOGAN, Utah-Monday, Utah State men’s basketball coach Craig Smith announced the addition of David Ragland to his staff as an assistant coach.Ragland comes to the Aggies after a 2-year stint on the staff of the Valparaiso Crusaders of the Missouri Valley Conference.Last season, the Crusaders defeated the Aggies 72-65 during the Mountain West-Missouri Valley Challenge with Ragland on the staff.In 2017, he was instrumental in the Crusaders’ Horizon League regular season championship which saw them earn an at-large berth in the NIT.While at Valparaiso, Ragland’s primary responsibility was offense and he was successful as the Crusaders finished in the top five of the Missouri Valley Conference last season in both points per game and scoring margin, while finishing third in field goal percentage.Prior to his arrival at Valpariso, Ragland spent one season at Northern Kentucky (2015-16) and helped the Norse find their feet during their first season in the Horizon League.Ragland was on the Bowling Green staff in 2014-15, helping Falcons star Richaun Holmes earn first-team all-Mid American Conference honors, while the squad won 21 games that season.Before this, Ragland was at Indiana State from 2010-2014, helping the Sycamores to the NCAA Tournament in 2011, while they made the postseason all four years during his time at Terre Haute, Ind.During his playing days, Ragland was with Division II Southern Indiana and helped the Screaming Eagles win 47 games and leading the team in assists each year he was on the squad.He also played for the Division II Missouri Southern State Lions, helping the team to a 30-3 record and a place in the Division II Final Four.After his playing days, Ragland started his coaching career as an assistant at Franklin Phillips C.C. of Borger, Texas.After his time with the Plainsmen, he became the head coach at Vincennes after three years as an assistant with the Trailblazers.The highlight of his tenure was leading the squad to the NJCAA District Tournament finals during the 2009-10 season.Ragland and his wife have two children, Ava and Joshua.last_img read more

  • Disabled teen honored at World Series says he found inspiration in Jackie Robinson story

    first_img FacebookTwitterLinkedInEmailCourtesy Tracey Quist(BOSTON) — A high school sophomore from Wyoming recently had a “once-in-a-lifetime” experience, all thanks to an essay he’d written about baseball legend Jackie Robinson.Jesse Quist was recognized on Oct. 24 at Fenway Park, home of the Boston Red Sox, as one of two winners in Major League Baseball’s 2018 “Breaking Barriers: In Sports, In Life” essay contest.Quist, 15, of Cheyenne, Wyoming, is a Korean adoptee with two parents and seven siblings. He was born missing most of both of his arms. He has no hands but uses what he calls “nubbins” — two fingers on his left arm and one finger on his right.As part of his winnings, Quist was invited to attend Games 1 and 2 of the World Series between the Red Sox and Los Angeles Dodgers.“It was crazy,” Quist told ABC News about being at the game. “It was definitely one of the loudest baseball games that I’ve ever been to. … The crowd was wild.”The Red Sox defeated the Dodgers in the end, taking the series, 4-1, and winning the 2018 World Series. Quist, a Colorado Rockies fan, said he was just happy to be in the stands enjoying the moment.The contest — a joint effort by Jackie Robinson’s daughter, Sharon Robinson, the MLB, and children’s publisher Scholastic — asks students in grades 4 to 9 to discuss how they’d used values exemplified by Jackie Robinson to overcome “barriers or obstacles” in their lives.Quist’s essay was chosen among 13,000 essays submitted from around the U.S., Puerto Ric and Canada, according to the MLB.“It was just a shock to me. I didn’t think I was going to win,” he told ABC News. “I just wanted to get my story out there.”He told ABC News that when his mother found the essay contest, the topic really spoke to him, particularly because he’d seen the movie “42” about Jackie Robinson, an MLB Hall of Famer who broke baseball’s color barrier in 1947 when he became the first black athlete to play for the league.In his essay, Quist said in part, “I have pretty much learned how to do things differently and in my own unique way. … To learn how to write, eat and basically do everything needed for everyday life, I used determination, commitment, persistence and excellence.”He said that he had incredible respect for the baseball player.“It can be very frustrating knowing that everywhere you go, there will always be someone whispering about you. … There’s no doubt in my mind that Jackie Robinson experienced the same thing: the pointing and staring and whispering,” Quist wrote.“(Jackie Robinson) just went out and played baseball and, you know, showed the world that he deserved to be in the MLB,” Quist told ABC News. “I wanted to be like him. … I’ve got a book about Jackie Robinson sitting underneath my alarm clock in my room.”Quist, who attended high school last year but is now home-schooled, said an everyday challenge was people’s reactions to him.“Everywhere I go, I’m going to get, you know, stared at, pointed at. That’s always an everyday challenge, everywhere I go,” he said.Quist, who has run cross-country and track as well as played soccer and basketball, said he’d like to go to college and attend law school, or be an English teacher or professor.“I try not to let anything stop me,” he said. “Jackie Robinson definitely showed that you can do anything that you want to do as long as you’re driven to do it.”Copyright © 2018, ABC Radio. All rights reserved. November 2, 2018 /Sports News – National Disabled teen honored at World Series says he found inspiration in Jackie Robinson story Written bycenter_img Beau Lundlast_img read more

  • Four Utah Football Stars To Return For Senior Season

    first_imgAnae (the Pac-12’s sack leader with 8 sacks) and Fotu were named to the all-conference first team. The returning Utes include defensive end Bradlee Anae, defensive tackle Leki Fotu, running back Zack Moss and cornerback Julian Blackmon, all of whom were named as all Pac-12 performers in 2018. Written by Moss rushed for 1,092 yards and 11 touchdowns and Blackmon is a two-time All-Pac 12 defensive back out of Layton High School. January 7, 2019 /Sports News – Local Four Utah Football Stars To Return For Senior Seasoncenter_img Brad James FacebookTwitterLinkedInEmailSALT LAKE CITY-Monday, four Utah football star juniors announced they are returning for their senior campaigns in 2019. Tags: Bradlee Anae/Julian Blackmon/Layton High School/Leki Fotu/Utah Football/Zack Mosslast_img read more

  • Scoreboard roundup — 8/21/19

    first_img Written by August 22, 2019 /Sports News – National Scoreboard roundup — 8/21/19 Beau Lundcenter_img FacebookTwitterLinkedInEmailiStock(NEW YORK) — Here are the scores from Wednesday’s sports events:MAJOR LEAGUE BASEBALLINTERLEAGUENY Mets 4, Cleveland 3 Philadelphia 5, Boston 2LA Dodgers 2, Toronto 1AMERICAN LEAGUETampa Bay 7, Seattle 6Chi White Sox 4, Minnesota 0Baltimore 8, Kansas City 1Detroit 2, Houston 1Texas 8, LA Angels 7Oakland 6, NY Yankees 4 NATIONAL LEAGUECincinnati 4, San Diego 2Colorado 7, Arizona 2Washington 11, Pittsburgh 1Atlanta 5, Miami 0Chi Cubs 12, San Francisco 11Milwaukee 5, St. Louis 3MAJOR LEAGUE SOCCERNew York City FC 1, Columbus 0New York 2, D.C. United 1San Jose 0, Los Angeles FC 0Copyright © 2019, ABC Radio. All rights reserved.last_img read more