scholarly journals Airborne surface profiling of glaciers: a case-study in Alaska

1996 ◽  
Vol 42 (142) ◽  
pp. 538-547 ◽  
Author(s):  
Κ. A. Echelmeyer ◽  
W. D. Harrison ◽  
C. F. Larsen ◽  
J. Sapiano ◽  
Mitchell J. E. ◽  
...  
Keyword(s):  
Time Intervals ◽  
Glacier Surface ◽  
Alaska Range ◽  
Thickness Change ◽  
Surface Profiling ◽  
Bear Lake ◽  
South Central ◽  
Short Time

AbstractA relatively lightweight and simple airborne system for surface elevation profiling of glaciers in narrow mountain valleys has been developed and tested. The aircraft position is determined by kinematic global positioning system (GPS) methods. The distance to the glacier surface is determined with a laser ranger. The accuracy is about 0.3 m, sufficient to permit future changes to be observed over short time intervals. Long-term changes can be estimated by comparison of profiles with existing maps. Elevation profiles obtained in 1993–94 from three glaciers in central and south-central Alaska are compared with maps made about 1950. The resulting area-averaged, seasonally corrected thickness changes during the interval are: Gulkana Glacier (central Alaska Range)–11 m, Worthington Glacier (central Chugach Mountains) +7 m, and Bear Lake Glacier (Kenai Mountains) −12 m. All three glaciers retreated during the interval of comparison. The estimated uncertainty in the average thickness change is ±5 m. which is mainly due to errors in the existing maps. Constraints on the accuracy of the maps are obtained by profiling in proglacial areas.

scholarly journals Airborne surface profiling of glaciers: a case-study in Alaska

1996 ◽  
Vol 42 (142) ◽  
pp. 538-547 ◽  
Author(s):  
Κ. A. Echelmeyer ◽  
W. D. Harrison ◽  
C. F. Larsen ◽  
J. Sapiano ◽  
Mitchell J. E. ◽  
...  
Keyword(s):  
Time Intervals ◽  
Glacier Surface ◽  
Alaska Range ◽  
Thickness Change ◽  
Surface Profiling ◽  
Bear Lake ◽  
South Central ◽  
Short Time

AbstractA relatively lightweight and simple airborne system for surface elevation profiling of glaciers in narrow mountain valleys has been developed and tested. The aircraft position is determined by kinematic global positioning system (GPS) methods. The distance to the glacier surface is determined with a laser ranger. The accuracy is about 0.3 m, sufficient to permit future changes to be observed over short time intervals. Long-term changes can be estimated by comparison of profiles with existing maps. Elevation profiles obtained in 1993–94 from three glaciers in central and south-central Alaska are compared with maps made about 1950. The resulting area-averaged, seasonally corrected thickness changes during the interval are: Gulkana Glacier (central Alaska Range)–11 m, Worthington Glacier (central Chugach Mountains) +7 m, and Bear Lake Glacier (Kenai Mountains) −12 m. All three glaciers retreated during the interval of comparison. The estimated uncertainty in the average thickness change is ±5 m. which is mainly due to errors in the existing maps. Constraints on the accuracy of the maps are obtained by profiling in proglacial areas.

scholarly journals Orbital pacing of carbon fluxes by a ∼9-My eccentricity cycle during the Mesozoic

2015 ◽  
Vol 112 (41) ◽  
pp. 12604-12609 ◽  
Author(s):  
Mathieu Martinez ◽  
Guillaume Dera
Keyword(s):  
Carbon Cycle ◽  
Orbital Forcing ◽  
Time Intervals ◽  
Sea Level Fluctuations ◽  
The Past ◽  
Paleoenvironmental Changes ◽  
Chaotic Diffusion ◽  
Orbital Cycles ◽  
Short Time

Eccentricity, obliquity, and precession are cyclic parameters of the Earth’s orbit whose climatic implications have been widely demonstrated on recent and short time intervals. Amplitude modulations of these parameters on million-year time scales induce ‟grand orbital cycles,” but the behavior and the paleoenvironmental consequences of these cycles remain debated for the Mesozoic owing to the chaotic diffusion of the solar system in the past. Here, we test for these cycles from the Jurassic to the Early Cretaceous by analyzing new stable isotope datasets reflecting fluctuations in the carbon cycle and seawater temperatures. Our results document a prominent cyclicity of ∼9 My in the carbon cycle paced by changes in the seasonal dynamics of hydrological processes and long-term sea level fluctuations. These paleoenvironmental changes are linked to a great eccentricity cycle consistent with astronomical solutions. The orbital forcing signal was mainly amplified by cumulative sequestration of organic matter in the boreal wetlands under greenhouse conditions. Finally, we show that the ∼9-My cycle faded during the Pliensbachian, which could either reflect major paleoenvironmental disturbances or a chaotic transition affecting this cycle.

Load Segmentation for Convergence of Distribution Automation and Advanced Metering Infrastructure Systems

2014 ◽  
Vol 15 (6) ◽  
pp. 607-619 ◽  
Author(s):  
Balakrishna Pamulaparthy ◽  
Swarup KS ◽  
Rajagopal Kommu
Keyword(s):  
Low Voltage ◽  
Distribution Automation ◽  
Advanced Metering Infrastructure ◽  
Distribution Grid ◽  
Smart Meters ◽  
Time Intervals ◽  
Power Restoration ◽  
Advanced Metering ◽  
Short Time

Abstract Distribution automation (DA) applications are limited to feeder level today and have zero visibility outside of the substation feeder and reaching down to the low-voltage distribution network level. This has become a major obstacle in realizing many automated functions and enhancing existing DA capabilities. Advanced metering infrastructure (AMI) systems are being widely deployed by utilities across the world creating system-wide communications access to every monitoring and service point, which collects data from smart meters and sensors in short time intervals, in response to utility needs. DA and AMI systems convergence provides unique opportunities and capabilities for distribution grid modernization with the DA system acting as a controller and AMI system acting as feedback to DA system, for which DA applications have to understand and use the AMI data selectively and effectively. In this paper, we propose a load segmentation method that helps the DA system to accurately understand and use the AMI data for various automation applications with a suitable case study on power restoration.

Strong anthropogenic signals in historic forest fire regime: a detailed spatiotemporal case study from south-central Norway

2013 ◽  
Vol 43 (9) ◽  
pp. 836-845 ◽  
Author(s):  
Ken Olaf Storaunet ◽  
Jørund Rolstad ◽  
Målfrid Toeneiet ◽  
Ylva-li Blanck
Keyword(s):  
Forest Fires ◽  
Boreal Forests ◽  
Fire Regime ◽  
Fire Severity ◽  
Fire Regimes ◽  
Fire Scars ◽  
Time Intervals ◽  
Slash And Burn ◽  
South Central

To better understand the historic range of variability in the fire regime of Fennoscandian boreal forests we cross-dated 736 fire scars of remnant Scots pine (Pinus sylvestris L.) wood samples in a 3.6 km2 section of the Trillemarka-Rollagsfjell Reserve of south-central Norway. Using a kernel range application in GIS we spatially delineated 57 individual forest fires between 1350 and the present. We found a strong anthropogenic signal in the fire regime from 1600 and onwards: (i) infrequent variably sized fires prior to 1600 shifted to frequent fires gradually decreasing in size during the 1600s and 1700s, with only a few small fires after 1800; (ii) time intervals between fires and the hazard of burning showed substantial differences pre- and post-1600; (iii) fire seasonality changed from late- to early-season fires from the 1626 fire and onwards; and (iv) fire severity decreased gradually over time. Written sources corroborated our results, narrating a history where anthropogenic forest fires and slash-and-burn cultivation expanded with the increasing population from the late 1500s. Concurrently, timber resources increased in value, gradually forcing slash-and-burn cultivators to abandon fires on forest land. Our results strengthen and expand previous Fennoscandian findings on the anthropogenic influence of historic fire regimes.

scholarly journals Geodetic mass balance of Abramov Glacier from 1975 to 2015

2021 ◽  
pp. 1-12
Author(s):  
Florian Denzinger ◽  
Horst Machguth ◽  
Martina Barandun ◽  
Etienne Berthier ◽  
Luc Girod ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Central Asia ◽  
Aerial Imagery ◽  
Time Intervals ◽  
Thickness Change ◽  
Time Period ◽  
Stereo Imagery ◽  
Geodetic Mass Balance

Abstract Multi-decadal mass loss estimates are available for few glaciers of Central Asia. On Abramov Glacier (Pamir-Alay, Kyrgyzstan), comprehensive long-term glaciological measurements have been carried out from 1968 to 1999 and re-initiated in 2011. A climatological interpretation of this benchmark glacier in Central Asia requires bridging the gap between historical and renewed measurements. This is achieved here by computing the geodetic mass balance from 1975 to 2015 using previously unreleased Soviet aerial imagery and Pléaides stereo-imagery. During 1975–2015, Abramov Glacier lost 2.2 km2 (8.2%) of its area. The mean annual thickness change was − 0.43 ± 0.14 m a−1 for the period 1975–2015, corresponding to a volume change of − 0.45 ± 0.15 km3. The average specific geodetic mass balance amounts to − 0.38 ± 0.12 m w.e. a−1. The 1975–2015 glacier mass loss lies within the range of glaciological and geodetic mass-balance estimates that were previously published for disparate and shorter time intervals since 1968. This study covers a much longer time period than earlier geodetic estimates and demonstrates the capacity to geodetically constrain glacier change at high spatial resolution in Central Asia using historic aerial imagery and Structure from Motion techniques. Therefore, it could serve as a benchmark for future studies of regional mass change.

scholarly journals Gamma-Ray Orbital Modulation of the Transitioning Millisecond Pulsar Binary XSS J12270–4859

2022 ◽  
Vol 924 (2) ◽  
pp. 91
Author(s):  
Hongjun An
Keyword(s):  
Gamma Ray ◽  
Optical Data ◽  
Large Area ◽  
Time Intervals ◽  
Optical Telescope ◽  
X Ray ◽  
Low Mass ◽  
Orbital Modulation ◽  
Short Time

Abstract We report on gamma-ray orbital modulation of the transitioning MSP binary XSS J12270–4859 detected in the Fermi Large Area Telescope (LAT) data. We use long-term optical data taken with the XMM-Newton OM and the Swift UltraViolet Optical Telescope to inspect radio timing solutions that are limited to relatively short time intervals and find that extrapolation of the solutions aligns well with the phasing of the optical data over 15 yr. The Fermi-LAT data folded on the timing solutions exhibit significant modulation (p = 5 × 10−6) with a gamma-ray minimum at the inferior conjunction of the pulsar. Intriguingly, the source seems to show similar modulation in both the low-mass X-ray binary and the MSP states, implying that mechanisms for gamma-ray emission in the two states are similar. We discuss these findings and their implications using an intrabinary shock scenario.

Distribution and behavior of ice worms (Mesenchytraeus solifugus) in south-central Alaska

2001 ◽  
Vol 79 (10) ◽  
pp. 1813-1821 ◽  
Author(s):  
Daniel H Shain ◽  
Tarin A Mason ◽  
Angela H Farrell ◽  
Lisa A Michalewicz
Keyword(s):  
Diurnal Cycle ◽  
Visible Spectrum ◽  
Gulf Of Alaska ◽  
Lateral Movement ◽  
Glacier Surface ◽  
Alaska Range ◽  
South Central ◽  
Glacier Ice ◽  
And Behavior

The ice worm, Mesenchytraeus solifugus ssp. rainierensis, is the only known annelid that survives in glacier ice. We report the locations of eight ice worm populations in south-central Alaska, including the northern- and western-most extent of known ice worm habitation. All ice worms identified in this study inhabit coastal glaciers proximal to the Gulf of Alaska. They were found in a variety of habitats including level snowfields, steep avalanche cones, crevasse walls, glacial rivers and pools, and hard glacier ice. Ice worms were not found on all coastal glaciers nor were they found in Alaska's interior (the Alaska Range). Ice worms on Byron Glacier, Alaska, totaled ~30 million and were distributed on seven distinct avalanche cones. They displayed a diurnal cycle, appearing on the glacier surface several hours before sunset and penetrating back into the glacier shortly after sunrise. Experiments suggest that ice worms preferentially penetrate the glacier beneath surface algae, Chlamydomonas nivalis, to a depth between 15 and 100 cm and resurface at a proximal location. Lateral movement of ice worms on the glacier surface can reach speeds of ~3 m/h. Ice worms on Byron Glacier avoided light, but did not respond preferentially to different wavelengths in the visible spectrum. Finally, ice worms displayed an unexpected attraction to heat.

scholarly journals Capitalizing on short-term collaborative projects: A special collections case study

2019 ◽  
Vol 80 (8) ◽  
pp. 452
Author(s):  
Erin Passehl-Stoddart ◽  
Ashlyn Velte
Keyword(s):  
Science Fiction ◽  
Short Term ◽  
Special Collections ◽  
Cross Training ◽  
Student Employees ◽  
Available Technology ◽  
The University ◽  
Short Time

After the University of Idaho (UI) Library Special Collections and Archives (SPEC) received an unexpected bequest of approximately 340 boxes of science fiction books and manuscript materials, faculty and staff had to think creatively about how to appraise, clean, preserve, and provide basic access to the collection within a short time frame.Embracing the idea that short-term collaborative projects require less formality, which makes them “low-hanging fruit” and more likely to succeed than long-term collaborative projects, SPEC implemented successful strategies such as cross-training library student employees from other units, applying for use of temporary space on campus, and creative use of available technology. Short-term projects require different approaches and resources than a long-term project. Lessons about flexibility, student learning, and using available technology can be used by other academic libraries facing short-term projects that can at first seem overwhelming.

scholarly journals MODERN PENSION TRACKING SYSTEM – THE CASE OF SLOVAK ORANGE ENVELOPE PLATFORM

2021 ◽  
Author(s):  
Daniela Danková ◽  
◽  
Ján Šebo ◽  
Ivan Králik ◽  
◽  
...  
Keyword(s):  
Tracking System ◽  
Good Practice ◽  
Research Front ◽  
Tracking Systems ◽  
Eu Member States ◽  
Key Aspects ◽  
Short Time ◽  
Term Objective

European Commission has a long-term objective of tackling the demographic issues of EU member states by creating a network of national pension tracking systems. The initiative launched in 2021 aims to present good practices in building modern pension tracking systems. The paper examines key aspects of a modern, consumer-driven non-governmental platform providing users with the features of pension entitlements across all pension pillars in Slovakia. The methodology is built on the case-study where governance, research, front-end and data management issues are elaborated. The paper presents in-depth steps and robustness of microsimulation model applied for the pension tracking platform. The results could serve for other countries and modern PensionTech providers as a good practice and a guideline to create a comprehensive integrated pension tracking system with minimum development and operational costs and extremely short time-to-market duration.

A review of analogues of alkaline alteration with regard to long-term barrier performance

2011 ◽  
Vol 75 (4) ◽  
pp. 2401-2418 ◽  
Author(s):  
D. Savage
Keyword(s):  
Mineral Dissolution ◽  
Time Intervals ◽  
Barrier Materials ◽  
Disturbed Zone ◽  
Natural Analogues ◽  
Zeolite Formation ◽  
Hydraulic Gradients ◽  
Short Time

AbstractCement and concrete will be used as fracture grouts, shotcrete, tunnel and borehole seals, and as matrices for waste encapsulationinter aliain geological repositories for radioactive wastes. Alteration of the host rock and/or swelling clay in waste package buffers and tunnel backfills by hyperalkaline solutions from cement/concrete may be deleterious to system performance through changes in the physicochemical properties of these barrier materials.Analogue systems (and timescales) relevant to the understanding of the alkaline disturbed zone include: industrial analogues, such as alkaline flooding of hydrocarbon reservoirs (up to 30 y), cement-aggregate reactions (up to 100 y) and the Tournemire tunnel (up to 125 y); and natural analogues, including the hyperalkaline springs at Maqarin, Jordan (more than 100,000 y), saline, alkaline lakes (more than 1,000,000 y) and certain fracture fillings in granites (more than 1,000,000 y).These systems show that alkaline alteration can be observed for thousands of years over distance scales of hundreds of metres under extreme conditions of hydraulic gradients in fractured rocks (Maqarin), but may be limited to a few centimetres over tens to a hundred years in mudstone (Tournemire). Important reaction mechanisms for retardation of alkaline fluids include: fluid mixing (alkaline oil floods, Maqarin), ion exchange (alkaline oil floods, Tournemire) and kinetic mineral dissolution-precipitation reactions (all systems studied). Qualitative and quantitative kinetic data for mineral reactions are available from cement aggregate reactions and the Searles Lake analogue, respectively. Short-term alteration observed in cement-aggregates is characterized by calcium silicate hydrate (C-S-H) minerals and incipient zeolite formation, whereas evidence from the Tournemire tunnel shows the growth of K-feldspar after relatively short time intervals (tens to a hundred years). There is a tendency for alkaline alteration to result in porosity decreases, but locally, porosity may be enhanced (e.g. near-injection well interactions in alkaline oil floods, or at fracture margins at Maqarin, Jordan). Data from industrial and natural analogues may thus supply some key data for bridging time and space scales between laboratory andin situexperiments on one hand and the requirements for safety assessment on the other.

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