Sedimentary basins on the east flank of the Antarctic Peninsula: proposed nomenclature

first_imgThe first fossils from Antarctica were collected from Seymour Island in December 1892, during the voyage of the Jason under Captain C.A. Larsen. The Swedish South Polar Expedition of 1901–1903, led by Otto Nordenskjöld, proved that there were extensive deposits of fossiliferous Cretaceous and Tertiary sedimentary rock in the James Ross Island area. This was confirmed by later geological mapping (Bibby 1966). Subsequent investigations have led to the establishment of various lithostratigraphic schemes (e.g. Ineson et al. 1986), and interpretation of the sedimentary history in terms of basin evolution (Elliot 1988, Macdonald et al. 1988). Unfortunately, different names have been proposed for the depositional basin, with consequent confusion. The purpose of this note is to review previous usage and propose a new consistent nomenclature for the sedimentary basins east of the Antarctic Peninsula.last_img read more

On the fractal nature of the magnetic field energy density in the solar wind

first_imgThe solar wind exhibits scaling typical of intermittent turbulence in the statistics of in situ fluctuations in both the magnetic and velocity fields. Intriguingly, quantities not directly accessed by theories of ideal, incompressible, MHD turbulence, such as magnetic energy density, B-2, nevertheless show evidence of simple fractal (self-affine) statistical scaling. We apply a novel statistical technique which is a sensitive discriminator of fractality to the B-2 timeseries from WIND and ACE. We show that robust fractal behaviour occurs at solar maximum and determine the scaling exponents. The probability density function (PDF) of fluctuations at solar maximum and minimum are distinct. Power law tails are seen at maximum, and the PDF is reminiscent of a Levy flight.last_img

Tropical daytime lower D-region dependence on sunspot number

first_imgObserved phases and amplitudes of VLF radio signals propagating on (near) tropical all-sea paths, both short, ∼300 km, and long, ∼10 Mm, are used to find daytime parameter changes for the lowest edge of the (D-region of the) Earth’s ionosphere as the solar cycle advanced from a very low sunspot number of ∼5 up to ∼60, in the period 2009–2011. The VLF phases, relative to GPS 1-s pulses, and amplitudes were measured ∼100 km from the transmitter, where the direct ground wave is very dominant, ∼300 km from the transmitter, near where the ionospherically reflected waves form a (modal) minimum with the ground wave, and ∼10 Mm away where the lowest order waveguide mode is fully dominant. Most of the signals came from the 19.8 kHz, 1-MW transmitter, NWC, North West Cape, Australia, propagating ENE, mainly over the sea, to the vicinity of Karratha and Dampier on the NW coast of Australia and then on to Kauai, Hawaii, ∼10.6 Mm from NWC. Observations from the 8.1-Mm path NPM (21.4 kHz, Hawaii) to Dunedin, NZ, are also used. The sunspot number increase from ∼5 to ∼60 was found to coincide with a decrease in the height, H′, of the midday tropical ionosphere by 0.75 ± 0.25 km (from H′ ≈ 70.5 km to H′ ≈ 69.7 km) while the sharpness, β increased by 0.025 ± 0.01 km−1 (from β ≈ 0.47 km−1 to β ≈ 0.49 km−1) where H′ and β are the traditional height and sharpness parameters used by Wait and by the U.S. Navy in their Earth-ionosphere VLF radio waveguide programs.last_img read more

Regional and seasonal differences in microplankton biomass, productivity, and structure across the Scotia Sea: Implications for the export of biogenic carbon

first_imgSurveys of the microplankton communities of the Scotia Sea, Southern Ocean, were carried out during three separate seasons of interest, spring, summer, and autumn of consecutive years. The surveys were conducted along a south to north transect and covered areas of low and high productivity, as well as crossing deep, open water and shallow, bathymetric features. During the summer and autumn cruises, cluster analysis revealed four distinct communities that were broadly consistent between cruises. From south to north the zones in which the communities fell were as follows: SOUTH, stations in the south Scotia Sea; MID, stations in the central Scotia Sea; SW-SG, stations southwest of the island of South Georgia; and NW-SG, stations northwest of South Georgia. Two main groups dominated the microplankton communities in all zones and all seasons; diatoms and naked, heterotrophic dinoflagellates. However, the proportion of these groups, and the species of diatom present, varied between zones and between seasons. In the SOUTH zone, a cryptophyte bloom was observed during summer. Spring and autumn communities showed similar levels of Chl a (0.6–1.5 mg m−3) but shifted to increasing numbers and biomass of heavily silicified diatoms (Fragilariopsis spp. and Corethron pennatum). Dense, spring blooms of the MID zone were dominated by a weakly silicified diatom, Thalassiosira spp. This contrasted with production 10 times lower (∼0.2 g C m−2 d−1) during the dinoflagellate composed, summer and autumn cruises. Closer to the island of South Georgia, lightly silicified diatoms became increasingly prevalent. In the SW-SG zone, such diatoms were found both in low Chl a (0.3 mg m−3) spring-time waters and in short-lived summer blooms. Autumn communities saw a switch to dinoflagellates co-inciding with decreasing light levels and depletion of macronutrients. Downstream of South Georgia, in the NW-SG zone, high productivity (up to 2.8 g C m−2 d−1) and long lasting blooms (3–6 months) were found on all seasons surveyed. The NW-SG microplankton consisted of a mixed community with both heavily and weakly silicified diatoms, but also significant amounts of heterotrophic dinoflagellates. Using bloom dynamics, microplankton structure and diatom speciation of our 4 Scotia Sea zones, we propose the following potential export regimes: (1) SOUTH – weak export of carbon, (2) MID – episodic, dense pulses of carbon may be exported, (3) SW-SG – modest pulses of carbon may be exported, and (4) NW-SG – high export of biogenic carbon likely to occur.last_img read more

High genetic diversity and connectivity in a common mesopelagic fish of the Southern Ocean

first_imgMany marine pelagic fish species are characterized by subtle but complex genetic structures and dynamics, depending on the balance between current-mediated larval dispersal and adult active homing behavior. The circumantarctic continuous hydrodynamics of the Southern Ocean is a prime example of a system with a potentially great homogenizing effect among distant populations. We tested this hypothesis by analyzing the contemporary genetic relatedness among populations of a common and endemic mesopelagic fish of the Southern Ocean, Electrona antarctica. Seven newly developed species-specific microsatellite markers were used to investigate patterns of neutral genetic variation in 11 geographically widespread samples (n=400) collected between 2006 and 2007. We detected a very high level of genetic diversity, but a striking lack of genetic differentiation on a circumantarctic scale, indicating large effective population sizes complemented with high levels of admixture. These findings underscore the large scale homogenizing effect of the Southern Coastal Current, leading to a high level of connectivity of our model species in the Southern Ocean, which is congruent with its huge biomass and central role in marine food webs. As an important Antarctic marine living resource this species may as such be managed on a circumantarctic level, although the demographic stability of this stock should be estimated urgently.last_img read more

Bedmap2: improved ice bed, surface and thickness datasets for Antarctica

first_imgWe present Bedmap2, a new suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60° S. We derived these products using data from a variety of sources, including many substantial surveys completed since the original Bedmap compilation (Bedmap1) in 2001. In particular, the Bedmap2 ice thickness grid is made from 25 million measurements, over two orders of magnitude more than were used in Bedmap1. In most parts of Antarctica the subglacial landscape is visible in much greater detail than was previously available and the improved data-coverage has in many areas revealed the full scale of mountain ranges, valleys, basins and troughs, only fragments of which were previously indicated in local surveys. The derived statistics for Bedmap2 show that the volume of ice contained in the Antarctic ice sheet (27 million km3) and its potential contribution to sea-level rise (58 m) are similar to those of Bedmap1, but the mean thickness of the ice sheet is 4.6% greater, the mean depth of the bed beneath the grounded ice sheet is 72 m lower and the area of ice sheet grounded on bed below sea level is increased by 10%. The Bedmap2 compilation highlights several areas beneath the ice sheet where the bed elevation is substantially lower than the deepest bed indicated by Bedmap1. These products, along with grids of data coverage and uncertainty, provide new opportunities for detailed modelling of the past and future evolution of the Antarctic ice sheets.last_img read more

Remote control of Filchner‐Ronne Ice Shelf melt rates by the Antarctic Slope Current

first_imgRecent work on the Filchner‐Ronne Ice Shelf (FRIS) system has shown that a redirection of the coastal current in the southeastern Weddell Sea could lead to a regime change in which an intrusion of warm Modified Circumpolar Deep Water results in large increases in the basal melt rate. Work to date has mostly focused on how increases in the Modified Circumpolar Deep Water crossing the continental shelf break leads directly to heat driven changes in melting in the ice‐shelf cavity. In this study, we introduce a Weddell Sea regional ocean model configuration with static ice shelves. We evaluate a reference simulation against radar observations of melting, and find good agreement between the simulated and observed mean melt rates. We analyse 28 sensitivity experiments that simulate the influence of changes in remote water properties of the Antarctic Slope Current on basal melting in the FRIS. We find that remote changes in salinity quasi‐linearly modulate the mean FRIS net melt rate. Changes in remote temperature quadratically vary the FRIS net melt rate. In both salinity and temperature perturbations, the response is rapid and transient, with a recovery time‐scale of 5‐15 years dependent on the size/type of perturbation. We show that the two types of perturbations lead to different changes on the continental shelf, and that ultimately different factors modulate the melt rates in the FRIS cavity. We discuss how these results are relevant for ocean hindcast simulations, sea level, and melt rate projections of the FRIS.last_img read more

Southern Utah Football Faces North Alabama To Open Season Saturday

first_img Brad James Written by Tags: Big Sky Conference/Demario Warren/North Alabama Lions/SUU Football August 30, 2018 /Sports News – Local Southern Utah Football Faces North Alabama To Open Season Saturday FacebookTwitterLinkedInEmailCEDAR CITY, Utah-Southern Utah football commences the 2018 season Saturday by hosting North Alabama at Eccles Coliseum.Over the course of the past three seasons, the Thunderbirds sport a 14-2 (.875) record at home.The Thunderbirds are also part of history Saturday as their opponent, the North Alabama Lions, a traditional Division II power, are playing their first game at the Division I level.Under Demario Warren, who became the Thunderbirds’ head coach in 2015, SUU has won two Big Sky Conference titles in his three seasons and has amassed a record of 23-12 (.657).Last February, Warren signed a contract extension which will keep him at Cedar City through 2022.last_img read more

Kalin Bennett becomes first athlete with autism to sign letter of intent to play D1 basketball

first_img Written by FacebookTwitterLinkedInEmailLink Hoops(BRANSON, Mo.) — The inspiring story of the week comes out of Kent State, and the team’s 2019 incoming basketball class.Kalin Bennett, 18, from Little Rock, Arkansas, is the first person with autism ever to sign a letter of intent with a Division 1 university. But the young man wants to be known for much more than just that.While Bennett knows his basketball skills made him the first student-athlete with autism to potentially compete at this level, he knows people will be cheering him on for other reasons as well.“I want to make an impact not just on the court, but with kids that are struggling with the same things I am,” he told Cleveland.com. “I want to use this platform to inspire other kids with autism and non-autism. I want to let them know, ‘Hey, if I can do this, you can do it, too.’ A lot of times they feel alone and by themselves, and I felt that same way growing up.”Bennett didn’t get to where he is now without his share of struggles. He didn’t walk until he was 4 years old, and didn’t talk until he was 7.But he graduated from high school with solid grades this past spring, and is now attending Link Year Prep in Branson, Missouri, a move many high-level athletes make before launching into D1 play.By signing Bennett, Kent State might be creating a precedent that other top schools may want to follow. The school works with the Autism Initiative for Research, Education, and Outreach (AIREO), and Partnering for Achievement and Learning Success (P.A.L.S.) — programs aimed at helping young adults with autism adjust to college life.Kent State currently has several dozen registered students living with autism, but there could be many more unregistered students, according to Gina Campana, the assistant director of the Office of Faculty Success and Inclusion. She added that the school is dedicated to raising awareness about autism and supporting anyone on the spectrum.Kalin will be joined at Kent State by his mother, Sonja Bennett, who has been a rock for him all his life.“I talked to [Kent State] coach [Rob Senderoff], and I was like, ‘Unless my mom comes, I ain’t comin’,” Bennett told Cleveland.com. “The separation anxiety really doesn’t upset me no more. But at the same time, I still like that support. Even when I have the best day of my life, I still want to make sure I see my mom’s face.”The college agreed, and Senderoff said the team is ready to make the proper adjustments on and off the court to make sure Bennett thrives both academically and athletically.But Bennett wants to make one thing clear — he wasn’t recruited because he has autism.“I just want to say one thing I had offers before Kent State and before prep school but the reason Kent and others recruited me isn’t because of my Autism and don’t get me wrong it’s cool to make history but they wanted me because I CAN HOOP AND I LOVE PLAYING BASKETBALL,” he tweeted on Tuesday as his story went viral.Copyright © 2018, ABC Radio. All rights reserved. Beau Lundcenter_img November 28, 2018 /Sports News – National Kalin Bennett becomes first athlete with autism to sign letter of intent to play D1 basketballlast_img read more

Scoreboard roundup — 1/10/19

first_img Written by January 11, 2019 /Sports News – National Scoreboard roundup — 1/10/19 Beau Lundcenter_img FacebookTwitterLinkedInEmailiStock(NEW YORK) — Here are the scores from Thursday’s sports events:NATIONAL BASKETBALL ASSOCIATIONMiami 115, Boston 99Denver 121, L.A. Clippers 1002OT San Antonio 154, Oklahoma City 147Sacramento 112, Detroit 102NATIONAL HOCKEY LEAGUEOT Columbus 4, Nashville 3NY Islanders 4, NY Rangers 3Washington 4, Boston 2Toronto 4, New Jersey 2Philadelphia 2, Dallas 1Tampa Bay 3, Carolina 1St. Louis 4, Montreal 1Minnesota 3, Winnipeg 2SO Edmonton 4, Florida 3OT Arizona 4, Vancouver 3San Jose 3, Vegas 2Ottawa 4, L.A. Kings 1TOP-25 COLLEGE BASKETBALL(2) Michigan 79, Illinois 69(5) Gonzaga 67, Pacific 36Copyright © 2019, ABC Radio. All rights reserved.last_img read more