The poleward edge of the mid-latitude trough—its formation, orientation and dynamics

first_imgData from the Advanced Ionospheric Sounder (AIS) deployed at Halley, Antarctica (76°S, 27°W; L = 4.2) and the Dynamics Explorer-2 spacecraft (DE-2) are used to investigate several aspects of the formation processes and dynamics of the poleward edge of the mid-latitude electron density trough. These include a study of the flux and energy of charged particles precipitating into the F-region as a function of Magnetic Local Time. It is found that local energetic electron precipitation is a major source of ionisation of the poleward edge in the evening sector, but after magnetic midnight transport processes become more important. Occasionally a significant increase in the flux of conjugate photo-electrons is co-located with the poleward edge of the trough in the morning sector. Some possible mechanisms are discussed but no firm conclusions are drawn. The combination of AIS and DE-2 data has allowed identification of significant longitudinal structure on the poleward edge of the trough that may be the result of substorm activity. It is found that the orientation of the poleward edge of the trough and the locus of the plasmapause predicted from the ‘tear-drop’ model vary in rather a similar manner with local time, though no close physical link between the two features is inferred from this coincidence. A comparison of the equatorward motion of the poleward edge on many nights is used to show that Kp is a poor index to use in any empirical model for predicting the temporal variations of the location of the trough. It is suggested that a more thorough understanding of the processes controlling the variability of the magnetospheric convection electric field is required before any significant improvement to the empirical models is likely to occur.last_img read more

Diel activity patterns of Carabidae, Staphylinidae and Perimylopidae (Coleoptera) at South Georgia, Sub-Antarctic

first_imgSix of the eight species of beetles at South Georgia, the southernmost beetles of the world, were investigated in outdoor arenas with pitfall traps for their diel patterns of locomotory activity. All of them were clearly nocturnal, the only exception being a small staphylinid which appeared to be active throughout the day and night. Activity of the other species was restricted to the dark period of the night, with little activity during twilight. Peak activity occurred before or at midnight. Activity was clearly correlated with temperature. Diurnal activity may involve a risk of overheating and desiccation, but could also have evolved in the past due to bird predation, which today is very low in the study arealast_img read more

No relationship between microsatellite variation and neonatal fitness in Antarctic fur seals, Arctocephalus gazella

first_imgPublished studies of wild vertebrate populations have almost universally reported positive associations between genetic variation measured at microsatellite loci and fitness, creating the impression of ubiquity both in terms of the species and the traits involved. However, there is concern that this picture may be misleading because negative results frequently go unpublished. Here, we analyse the relationship between genotypic variation at nine highly variable microsatellite loci and neonatal fitness in 1070 Antarctic fur seal pups born at Bird Island, South Georgia. Despite our relatively large sample size, we find no significant association between three different measures of heterozygosity and two fitness traits, birth weight and survival. Furthermore, increasing genetic resolution by calculating parental relatedness also yields no association between genetic variation and fitness. Our findings are consistent with necropsy data showing that most pups die from starvation or trauma, conditions that are unlikely to be influenced strongly by genetic factors, particularly if the benefits of high heterozygosity are linked to immune-related genes.last_img read more

Animated tectonic reconstruction of the Southern Pacific and alkaline volcanism at its convergent margins since Eocene times

first_imgAn animated reconstruction shows South Pacific plate kinematics, in the reference frame of West Antarctica, between 55 Ma and the present-day. The ocean floor in the region formed due to seafloor spreading between the Antarctic, Pacific, Phoenix and Nazca plates (a plate formed by fragmentation of the Farallon plate early in Oligocene times). The Pacific-Antarctic Ridge remained fairly stable throughout this time, migrating relatively northwestwards, by various mechanisms, behind the rapidly-moving Pacific plate. The Nazca and Phoenix plates also moved quickly, but relatively towards the cast or southeast, and were subducted in these directions beneath the South American and Antarctic plates. Segments of spreading centres forming at the trailing edges of the Nazca and Phoenix plates periodically collided with these subduction zones, resulting in the total destruction of the Nazca Phoenix spreading centre and the partial destruction of the Nazca-Antarctica spreading centre (the Chile Ridge) and Antarctic-Phoenix Ridge, which ceased to operate shortly before its northeasternmost three segments could collide with the Antarctic margin. Following collision of segments of the Chile Ridge, parts of the Antarctic plate underwent subduction at the Chile Trench. After these collisions, slab windows Should have formed beneath both the South American and Antarctic convergent margins, and the animation shows Occurrences of alkaline volcanism that have been, or can newly be, related to them. Further occurrences of alkali basalts, at the margins of the Powell Basin and, more speculatively, James Ross Island, can be related to the formation of a slab window beneath them following the collision of segments of the South America Antarctica spreading centre in the northwest Weddell Sea. (C) 2007 Elsevier B.V. All rights reserved.last_img read more

Microplastics in the Southern Ocean

first_imgThe Southern Ocean has the lowest densities of floating macroplastic litter in the world. It was thought that the region was relatively free of microplastic contamination. However, recent studies and citizen science projects have reported microplastics in deep-sea and shallow sediments and surface waters. Microplastics have been shown, in both laboratory experiments and field-based studies elsewhere in the world, to negatively impact a range of marine species including pelagic and benthic organisms. After reviewing available information on microplastics (including macroplastics as a source of microplastics) in the Southern Ocean, we present estimated microplastic concentrations, and identify potential sources and routes of transmission into the region. Estimates suggest that the amounts of microplastic pollution released into the region from ships and scientific research stations are likely to be negligible at the scale of the Southern Ocean, but may be significant on a local scale. Furthermore, predictions of microplastic concentrations from local sources are several orders of magnitude lower than levels reported in published sampling surveys. Sea surface transfer from lower latitudes is a likely contributor to Southern Ocean plastic concentrations.last_img read more

A review on the biodiversity, distribution and trophic role of cephalopods in the Arctic and Antarctic marine ecosystems under a changing ocean

first_imgCephalopods play an important role in polar marine ecosystems. In this review, we compare the biodiversity, distribution and trophic role of cephalopods in the Arctic and in the Antarctic. Thirty-two species have been reported from the Arctic, 62 if the Pacific Subarctic is included, with only two species distributed across both these Arctic areas. In comparison, 54 species are known from the Antarctic. These polar regions share 15 families and 13 genera of cephalopods, with the giant squid Architeuthis dux the only species confirmed to occur in both the Arctic and Antarctic. Polar cephalopods prey on crustaceans, fish, and other cephalopods (including cannibalism), whereas predators include fish, other cephalopods, seabirds, seals and whales. In terms of differences between the cephalopod predators in the polar regions, more Antarctic seabird species feed on cephalopods than Arctic seabirds species, whereas more Arctic mammal species feed on cephalopods than Antarctic mammal species. Cephalopods from these regions are likely to be more influenced by climate change than those from the rest of the World: Arctic fauna is more subjected to increasing temperatures per se, with these changes leading to increased species ranges and probably abundance. Antarctic species are likely to be influenced by changes in (1) mesoscale oceanography (2) the position of oceanic fronts (3) sea ice extent, and (4) ocean acidification. Polar cephalopods may have the capacity to adapt to changes in their environment, but more studies are required on taxonomy, distribution, ocean acidification and ecology.last_img read more

The Iceland Greenland Seas Project

first_imgA coordinated atmosphere-ocean research project, centered on a rare wintertime field campaign to the Iceland and Greenland Seas, seeks to determine the location and causes of dense water formation by cold-air outbreaks. The Iceland Greenland Seas Project (IGP) is a coordinated atmosphere-ocean research program investigating climate processes in the source region of the densest waters of the Atlantic Meridional Overturning Circulation. During February and March 2018, a field campaign was executed over the Iceland and southern Greenland Seas that utilized a range of observing platforms to investigate critical processes in the region – including a research vessel, a research aircraft, moorings, sea gliders, floats and a meteorological buoy. A remarkable feature of the field campaign was the highly-coordinated deployment of the observing platforms, whereby the research vessel and aircraft tracks were planned in concert to allow simultaneous sampling of the atmosphere, the ocean and their interactions. This joint planning was supported by tailor-made convection-permitting weather forecasts and novel diagnostics from an ensemble prediction system. The scientific aims of the IGP are to characterize the atmospheric forcing and the ocean response of coupled processes; in particular, cold-air outbreaks in the vicinity of the marginal-ice zone and their triggering of oceanic heat loss, and the role of freshwater in the generation of dense water masses. The campaign observed the lifecycle of a long-lasting cold-air outbreak over the Iceland Sea and the development of a cold-air outbreak over the Greenland Sea. Repeated profiling revealed the immediate impact on the ocean, while a comprehensive hydrographic survey provided a rare picture of these subpolar seas in winter. A joint atmosphere-ocean approach is also being used in the analysis phase, with coupled observational analysis and coordinated numerical modelling activities underway.last_img read more

Former USA Gymnastics head invokes Fifth Amendment rights at hearing about Nassar

first_img Written by — The former president of USA Gymnastics, Steve Penny, who resigned last month, appeared before a Senate Commerce subcommittee Tuesday after being subpoenaed, but he did not answer questions.Shortly after he responded to a series of queries by invoking his Fifth Amendment rights against self-incrimination, he was dismissed.As Penny exited, a woman stood up and shouted, “Shame!”The former USA Gymnastics head resigned in March 2017 amid allegations of sexual abuse against the national team’s former doctor, Larry Nassar. Nassar pleaded guilty to seven counts of child molestation later that year, but more than 130 women and girls, including Olympic gold medalists, had accused him of assaulting them. He was sentenced to up to 175 years in prison in January of this year.Rhonda Faehn, who served as Penny’s deputy at USA Gymnastics for only 37 days, also testified before the committee. She said she had brought up several allegations of misconduct to Penny, and each time had been told to keep quiet.“Each time I reported these incidents, I was told by Penny not to say anything to anyone for fear of possibly impeding any investigation of Nassar. I was not aware of any delay in contacting authorities or any efforts to misinform anyone of his departure,” Faehn said, as Penny sat next to her at the witness table.Faehn appeared along with former Michigan State University president Lou Anna Simon, who was also subpoenaed. Nassar was also an employee at MSU.“I want to say to all the survivors that I am really truly sorry for the abuse you suffered,” Simon said during her opening remarks. Simon resigned from MSU hours after Nassar’s sentencing in January.Before the hearing, several female gymnasts who were victims of Nassar spoke at a press conference, slamming USA Gymnastics for failing to protect them from predators.“If Steve Penny cannot be convicted in the court of justice, he should be convicted in the court of public opinion,” gymnast and survivor Jeanette Antolin said.In a statement released Monday, USA Gymnastics president and CEO Kerry Perry noted that the organization is implementing steps to prevent athletes from being abused in the future, including revamping its safety policies and procedures and providing financial assistance for counseling to athletes who have been abused.“We want all of our members to know that gymnastics is an incredible sport for young women and men, and one that is taught by individuals who have their athletes’ best interests at heart,” Perry said.Faehn also noted that teams are beginning to bring adult chaperones on trips when young athletes compete in overseas competitions.Copyright © 2018, ABC Radio. All rights reserved. June 5, 2018 /Sports News – National Former USA Gymnastics head invokes Fifth Amendment rights at hearing about Nassarcenter_img Beau Lundlast_img read more

USU Cross Country Commences Fall Camp Monday

first_imgAugust 20, 2018 /Sports News – Local USU Cross Country Commences Fall Camp Monday FacebookTwitterLinkedInEmailLOGAN, Utah-Monday, Utah State cross country commenced its fall camp at Altamont, Utah in preparation for their first meet of the season September 1.Both the Aggies’ men and women are coming off their best seasons in school history, with each program advancing to the NCAA championships last November.The women will be led by returning star, Alyssa Snyder, a junior out of Coalville, Utah. Last year, she finished 25th at the NCAA championships, posting a time of 20:03.39, while she also became an All-American for her heroics.The men will be looking to replace legendary runner Dillon Maggard and junior Luke Beattie of Woodstock, Ill. seems to be the one who can be up to the task. Tags: Altamont/Alyssa Snyder/Dillon Maggard/Luke Beattie/USU Cross Country Written by Brad Jameslast_img read more

SUU Cross Country Prepares For Idaho State Invitational

first_img FacebookTwitterLinkedInEmailCEDAR CITY, Utah-Coming off of a win at UC Riverside last Saturday, Southern Utah’s men’s and women’s cross country squads prepare to compete at Pocatello, Idaho at the Idaho State Invitational September 22.The men’s squad will seek to build upon its current #15 position in the national polls.The men’s projected lineup at this meet is Mark Bennett, Sage Ducote, Michael Finch, Jacob Francis, Thomas Grant, Jason Quinn, Jiree Riding and Max Spence.The women’s projected lineup consists of Danielle Beckstead, Josie Bushar, Brighton Glassman, Sarah Sargent, Haley Tanne and Samantha Taylor. Tags: Brighton Glassman/Danielle Beckstead/Haley Tanne/Idaho State Invitational/Jacob Francis/Jason Quinn/Jiree Riding/Josie Bushar/Mark Bennett/Max Spence/Michael Finch/Sage Ducote/Samantha Taylor/Sarah Sargent/Southern Utah/Thomas Grant/UC Riverside September 20, 2018 /Sports News – Local SUU Cross Country Prepares For Idaho State Invitational Written by Brad Jameslast_img read more