Large solar flares and their ionospheric D region enhancements

first_imgOn 4 November 2003, the largest solar flare ever recorded saturated the GOES satellite X-ray detectors, making an assessment of its size difficult. However, VLF radio phase advances effectively recorded the lowering of the VLF reflection height and hence the lowest edge of the Earth’s ionosphere. Previously, these phase advances were used to extrapolate the GOES 0.1–0.8 nm (“XL”) fluxes from saturation at X17 to give a peak magnitude of X45 ± 5 for this great flare. Here it is shown that a similar extrapolation, but using the other GOES X-ray band, 0.05–0.4 nm (“XS”), is also consistent with a magnitude of X45. Also reported here are VLF phase measurements from two paths near dawn: “Omega Australia” to Dunedin, New Zealand (only just all sunlit) and NPM, Hawaii, to Ny Alesund, Svalbard (only partly sunlit), which also give remarkably good extrapolations of the flare flux, suggesting that VLF paths monitoring flares do not necessarily need to be in full daylight. D region electron densities are modeled as functions of X-ray flux up to the level of the great X45 flare by using flare-induced VLF amplitudes together with the VLF phase changes. During this great flare, the “Wait” reflection height, H′, was found to have been lowered to ∼53 km or ∼17 km below the normal midday value of ∼70 km. Finally, XL/XS ratios are examined during some large flares, including the great flare. Plots of such ratios against XL can give quite good estimates of the great flare’s size (X45) but without use of VLF measurements.last_img read more

The discovery of a natural whale fall in the Antarctic deep sea

first_imgLarge cetacean carcasses at the deep-sea floor, known as ‘whale falls’, provide a resource for generalist-scavenging species, chemosynthetic fauna related to those from hydrothermal vents and cold seeps, and remarkable bone-specialist species such as Osedax worms. Here we report the serendipitous discovery of a late-stage natural whale fall at a depth of 1444 m in the South Sandwich Arc. This discovery represents the first natural whale fall to be encountered in the Southern Ocean, where cetaceans are abundant. The skeleton was situated within a seafloor caldera, in close proximity (<250 m) to active hydrothermal vents. We used a DNA barcoding approach to identify the skeleton as that of an Antarctic minke whale (Balaenoptera bonaerensis). The carcass was in an advanced state of decomposition, and its exposed bones were occupied by a diverse assemblage of fauna including nine undescribed species. These bone fauna included an undescribed species of Lepetodrilus limpet that was also present at the nearby hydrothermal vents, suggesting the use of whale-fall habitats as stepping stones between chemosynthetic ecosystems. Using Remotely Operated Vehicle (ROV) videography, we have quantified the composition and abundance of fauna on the whale bones, and tested a hypothesis that varying concentrations of lipids in the bones of whales may influence the microdistribution of sulfophilic whale-fall fauna. Our data supported the hypothesis that more lipid-rich bones support a greater abundance of sulfophilic bacterial mats, which are also correlated with the abundance of grazing limpets (Pyropelta sp.). The abundance of Osedax sp. on bones however, showed a negative correlation with the bacterial-mat percentage cover, and hence greatest abundance on bones predicted to have lowest lipid content.last_img read more

Challenges of deep-sea biodiversity assessments in the Southern Ocean

first_imgDespite recent progress in deep-sea biodiversity assessments in the Southern Ocean (SO), there remain gaps in our knowledge that hamper effi cient deep-sea monitoring in times of rapid climate change. These include geographical sampling bias, depth and size-dependent faunal gaps in biology, ecology, distribution, and phylogeography, and the evolution of SO species. The phenomena of species patchiness and rarity are still not well understood, possibly because of our limited understanding of physiological adaptations and thresholds. Even though some shallow water species have been investigated physiologically, community scale studies on the effects of multiple stressors related to ongoing environmental change, including temperature rise, ocean acidification, and shifts in deposition of phytoplankton, are completely unknown for deep-sea organisms. Thus, the establishment of long-term and coordinated monitoring programs, such as those rapidly growing under the umbrella of the Southern Ocean Observing System (SOOS) or the Deep Ocean Observing Strategy (DOOS), may represent unique tools for measuring the status and trends of deep-sea and SO ecosystemslast_img read more

Glacial melt under a porous debris layer

first_imgIn this paper we undertake a quantitative analysis of the dynamic process by which ice underneath a dry porous debris layer melts. We show that the incorporation of debris-layer airflow into a theoretical model of glacial melting can capture the empirically observed features of the so-called Østrem curve (a plot of the melt rate as a function of debris depth). Specifically, we show that the turning point in the Østrem curve can be caused by two distinct mechanisms: the increase in the proportion of ice that is debris-covered and/or a reduction in the evaporative heat flux as the debris layer thickens. This second effect causes an increased melt rate because the reduction in (latent) energy used for evaporation increases the amount of energy available for melting. Our model provides an explicit prediction for the melt rate and the temperature distribution within the debris layer, and provides insight into the relative importance of the two effects responsible for the maximum in the Østrem curve. We use the data of Nicholson and Benn (2006) to show that our model is consistent with existing empirical measurements.last_img read more

Sequence of events from the onset to the demise of the Last Interglacial: evaluating strengths and limitations of chronologies used in climatic archives

first_imgThe Last Interglacial (LIG) represents an invaluable case study to investigate the response of components of the Earth system to global warming. However, the scarcity of absolute age constraints in most archives leads to extensive use of various stratigraphic alignments to different reference chronologies. This feature sets limitations to the accuracy of the stratigraphic assignment of the climatic sequence of events across the globe during the LIG. Here, we review the strengths and limitations of the methods that are commonly used to date or develop chronologies in various climatic archives for the time span (∼140–100 ka) encompassing the penultimate deglaciation, the LIG and the glacial inception. Climatic hypotheses underlying record alignment strategies and the interpretation of tracers are explicitly described. Quantitative estimates of the associated absolute and relative age uncertainties are provided. Recommendations are subsequently formulated on how best to define absolute and relative chronologies. Future climato-stratigraphic alignments should provide (1) a clear statement of climate hypotheses involved, (2) a detailed understanding of environmental parameters controlling selected tracers and (3) a careful evaluation of the synchronicity of aligned paleoclimatic records. We underscore the need to (1) systematically report quantitative estimates of relative and absolute age uncertainties, (2) assess the coherence of chronologies when comparing different records, and (3) integrate these uncertainties in paleoclimatic interpretations and comparisons with climate simulations. Finally, we provide a sequence of major climatic events with associated age uncertainties for the period 140–105 ka, which should serve as a new benchmark to disentangle mechanisms of the Earth system’s response to orbital forcing and evaluate transient climate simulations.last_img read more

Comparison of elevation change detection methods from ICESat altimetry over the Greenland Ice Sheet

first_imgEstimation of the surface elevation change of the Greenland Ice Sheet (GrIS) is essential for understanding its response to recent and future climate change. Laser measurements from the NASA’s Ice, Cloud, and land Elevation Satellite (ICESat) created altimetric surveys of GrIS surface elevations over the 2003-2009 operational period of the mission. This paper compares four change detection methods using Release 634 ICESat laser altimetry data: repeat tracks (RTs), crossovers (XOs), overlapping footprints (OFPs), and triangulated irregular networks (TINs). All four methods begin with a consistently edited data set and yield estimates of volumetric loss of ice from the GrIS ranging from -193 to -269 km³/yr. Using a uniform approach for quantifying uncertainties, we find that volume change rates at the drainage system scale from the four methods can be reconciled within 1-σ uncertainties in just 5 of 19 drainage systems. Ice-sheet-wide volume change estimates from the four methods cannot be reconciled within 1-σ uncertainties. Our volume change estimates lie within the range of previously published estimates, highlighting that the choice of method plays a dominant role in the scatter of volume change estimates. We find that for much of the GrIS, the OFP and TIN methods yield the lowest volume change uncertainties because of their superior spatial distribution of elevation change rate estimates. However, the RT and XO methods offer inherent advantages, and the future work to combine the elevation change detection methods to produce better estimates is warranted.last_img read more

Length-weight and otolith size to standard length relationships in 12 species of Southern Ocean Myctophidae: a tool for predator diet studies

first_imgFish morphometric relationships are key tools for fisheries science and studies of food web dynamics and predator foraging behaviour, but parameterisations are limited for Southern Ocean myctophids (Family Myctophidae). New standard length (LS) to total mass (MT) relationships are therefore described for the 12 biomass‐dominant myctophid fish species living in the Scotia Sea, Southern Ocean, using the most comprehensive data collected in the region to date. New linear regressions for otolith size (length; OL and width; OW) and LS are also described. Significant (p < .01) LS–MT relationships were established for all species using simple non‐linear regression. Significant (p < .01) relationships between LS and both OL and OW were also determined for all species, with OW being the best predictor of LS in all but one species. Our study provides a comprehensive tool for reconstructing the myctophid component of marine predator diets that will improve future food web, predator behaviour and ecosystem studies in the Scotia Sea.last_img read more

Utah Baseball Visits Washington For Last Road Series of Season

first_img FacebookTwitterLinkedInEmailSEATTLE-Friday through Sunday, Utah baseball (12-28, 4-20 in Pac-12 play) plays its final road series of the season against the Washington Huskies (23-19, 9-12 in Pac-12 play). Sophomore right-handed pitcher Jack Enger leads the Huskies with a 3-0 record and a 2.52 ERA. The Huskies are led in batting average by junior catcher Nick Kahle (.352). He also leads Washington in RBI with 42. Sophomore right hander Josh Burgmann has 89 strikeouts to lead Washington in that statistic. Written by The Utes’ leading pitcher is senior left-hander Joshua Tedeschi (5-4) and he also leads the staff with 41 strikeouts. Senior right-handed pitcher/designated hitter Joe Wainhouse as nine home runs to lead Washington, while junior outfielder Connor Blair has eight homers. The Huskies lead the Utes 18-8 all-time. Tags: Connor Blair/Erick Migueles/Jack Enger/Joe Wainhouse/Josh Burgmann/Joshua Tedeschi/Nick Kahle/Oliver Dunn/Utah Baseball/Washington Baseball May 8, 2019 /Sports News – Local Utah Baseball Visits Washington For Last Road Series of Season Brad James The Utes are led on the season by junior outfielder Oliver Dunn in batting average (.350). Utah’s leader in home runs and RBI is senior outfielder Erick Migueles with 6 and 35, respectively.last_img read more

Bees Dump Aviators

first_img FacebookTwitterLinkedInEmail (Salt Lake City, UT)  —  Dustin Garneau homered twice as the Bees dumped the Las Vegas Aviators 9-6 in Salt Lake City.  Tags: PCL/Salt Lake Bees The Bees travel to face the Sacramento Rivercats today. Written by Garneau launched a three-run shot in the second inning and added a solo shot in the fifth.  Jarrett Parker added a solo shot and Jose Rojas launched a grand slam in the seventh.  May 21, 2019 /Sports News – Local Bees Dump Aviators Robert Lovelllast_img read more

Scoreboard roundup — 9/1/20

first_imgSeptember 2, 2020 /Sports News – National Scoreboard roundup — 9/1/20 Beau Lund Written bycenter_img FacebookTwitterLinkedInEmailiStockBy ABC News(NEW YORK) — Here are the scores from Tuesday’s sports events:MAJOR LEAGUE BASEBALLINTERLEAGUEMiami 3, Toronto 2Baltimore 9, NY Mets 5Atlanta 10, Boston 3Detroit 12, Milwaukee 1AMERICAN LEAGUENY Yankees 5, Tampa Bay 3Cleveland 10, Kansas City 1Minnesota 3, Chicago White Sox 2Texas 6, Houston 5Oakland at Seattle (Postponed)NATIONAL LEAGUESt. Louis 16, Cincinnati 2Philadelphia 6, Washington 0Chicago Cubs 8, Pittsburgh 7LA Dodgers 6, Arizona 3San Francisco 23, Colorado 5NATIONAL BASKETBALL ASSOCIATION PLAYOFFSBoston 102, Toronto 99 (Boston leads 2-0)Denver 80, Utah 78 (Denver wins series 4-3)NATIONAL HOCKEY LEAGUE PLAYOFFSPhiladelphia 4, NY Islanders 3 (OT) (NY leads 3-2)Vancouver 2, Vegas 1 (Vegas leads 3-2)WOMEN’S NATIONAL BASKETBALL ASSOCIATIONConnecticut 70, New York 65Atlanta 102, Indiana 90Phoenix 92, Las Vegas 85MAJOR LEAGUE SOCCERMontreal 1, Toronto FC 0Copyright © 2020, ABC Audio. All rights reserved.last_img read more