scholarly journals Ice-free valleys in the Neptune Range of the Pensacola Mountains, Antarctica: glacial geomorphology, geochronology and potential as palaeoenvironmental archives

2021 ◽  
pp. 1-28
Author(s):  
David Small ◽  
Michael J. Bentley ◽  
David J.A. Evans ◽  
Andrew S. Hein ◽  
Stewart P.H.T. Freeman
Keyword(s):  
Ice Sheet ◽  
The Arctic ◽  
Future Research ◽  
Geochronological Data ◽  
Glacial Geomorphology

Abstract We describe the glacial geomorphology and initial geochronology of two ice-free valley systems within the Neptune Range of the Pensacola Mountains, Antarctica. These valleys are characterized by landforms associated with formerly more expanded ice sheet(s) that were at least 200 m thicker than at present. The most conspicuous features are areas of supraglacial debris, discrete debris accumulations separated from modern-day ice and curvilinear ridges and mounds. The landsystem bears similarities to debris-rich cold-based glacial landsystems described elsewhere in Antarctica and the Arctic where buried ice is prevalent. Geochronological data demonstrate multiple phases of ice expansion. The oldest, occurring > 3 Ma, overtopped much of the landscape. Subsequent, less expansive advances into the valleys occurred > 2 Ma and > ~1 Ma. An expansion of some local glaciers occurred < 250 ka. This sequence of glacial stages is similar to that described from the northernmost massif of the Pensacola Mountains (Dufek Massif), suggesting that it represents a regional signal of ice-sheet evolution over the Plio-Pleistocene. The geomorphological record and its evolution over millions of years makes the Neptune Range valleys an area worthy of future research and we highlight potential avenues for this.

scholarly journals Using Saildrones to Validate Arctic Sea-Surface Salinity from the SMAP Satellite and from Ocean Models

2021 ◽  
Vol 13 (5) ◽  
pp. 831
Author(s):  
Jorge Vazquez-Cuervo ◽  
Chelle Gentemann ◽  
Wenqing Tang ◽  
Dustin Carroll ◽  
Hong Zhang ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
The Arctic ◽  
Future Research ◽  
Surface Salinity ◽  
Cold Temperatures ◽  
Yukon River ◽  
Arctic Sea ◽  
The Arctic Ocean

The Arctic Ocean is one of the most important and challenging regions to observe—it experiences the largest changes from climate warming, and at the same time is one of the most difficult to sample because of sea ice and extreme cold temperatures. Two NASA-sponsored deployments of the Saildrone vehicle provided a unique opportunity for validating sea-surface salinity (SSS) derived from three separate products that use data from the Soil Moisture Active Passive (SMAP) satellite. To examine possible issues in resolving mesoscale-to-submesoscale variability, comparisons were also made with two versions of the Estimating the Circulation and Climate of the Ocean (ECCO) model (Carroll, D; Menmenlis, D; Zhang, H.). The results indicate that the three SMAP products resolve the runoff signal associated with the Yukon River, with high correlation between SMAP products and Saildrone SSS. Spectral slopes, overall, replicate the −2.0 slopes associated with mesoscale-submesoscale variability. Statistically significant spatial coherences exist for all products, with peaks close to 100 km. Based on these encouraging results, future research should focus on improving derivations of satellite-derived SSS in the Arctic Ocean and integrating model results to complement remote sensing observations.

Profitability of the Northern Sea Route for liquid bulk shipping under post 2020 sulphur regulations

2020 ◽  
Vol 31 (2) ◽  
pp. 313-332
Author(s):  
Tuomo Keltto ◽  
Su-Han Woo
Keyword(s):  
Spot Market ◽  
The Arctic ◽  
Future Research ◽  
Estimation Model ◽  
Content Type ◽  
Freight Rates ◽  
Northern Sea Route ◽  
Financial Perspective ◽  
The Baltic ◽  
Regulation Compliance

PurposeThe purpose of this study is to evaluate the profitability of the Northern Sea Route (NSR) as a shipping lane from the financial perspective of shipping companies under post 2020 sulphur regulations.Design/methodology/approachThis study develops profit estimation model, and the profitability of the NSR is assessed for a Handymax Medium Range (MR) tanker vessel using scenarios in combination with spot market earning levels, the regulation compliance method and destination ports. The required freight rates are calculated to justify the decision of shipowners to transit a tanker from the Baltic spot market to the NSR navigation.FindingsResults suggest that the required freight rates from the Arctic trade to justify the transit to the NSR are higher than the actual agreed rates in the past, which implies low viability of the NSR as a regular shipping lane. It was also found that the required freight rates are affected by the spot market earning levels, compliance method and duration of the voyage.Research limitations/implicationsThis study takes a new approach on assessing the NSR viability by comprehensively assessing the annual profitability and including the spot market trade as an opportunity cost for the NSR shipping. Despite various scenarios used in this study, a sensitivity analysis would be useful for future research.Practical implicationsThis study suggests how much freight rates a shipping company would need to charge if it were to offer tanker shipping services to four major Asian ports while simultaneously operating at the Baltic Sea during the remainder of the year.Originality/valueThis study adopts a market-oriented approach by incorporating both earnings and costs (including opportunity costs) in the profitability model rather than merely analyzing the total cost of shipping via the NSR. This study also analyzes impact of IMO 2020 Sulphur regulation on the NSR profitability.

scholarly journals A new bedrock and surface elevation dataset for modelling the Greenland ice sheet

2003 ◽  
Vol 37 ◽  
pp. 351-356 ◽  
Author(s):  
Jonathan L. Bamber ◽  
Duncan J. Baldwin ◽  
S. Prasad Gogineni
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Detailed Comparison ◽  
Radar Data ◽  
The Arctic ◽  
Small Scale ◽  
Surface Model ◽  
Rock Outcrops ◽  
Bed Topography ◽  
Elevation Model

AbstractA new digital elevation model of the surface of the Greenland ice sheet and surrounding rock outcrops has been produced from a comprehensive suite of satellite and airborne remote-sensing and cartographic datasets. The surface model has been regridded to a resolution of 5 km, and combined with a new ice-thickness grid derived from ice-penetrating radar data collected in the 1970s and 1990s. A further dataset, the International Bathymetric Chart of the Arctic Ocean, was used to extend the bed elevations to include the continental shelf. The new bed topography was compared with a previous version used for ice-sheet modelling. Near the margins of the ice sheet and, in particular, in the vicinity of small-scale features associated with outlet glaciers and rapid ice motion, significant differences were noted. This was highlighted by a detailed comparison of the bed topography around the northeast Greenland ice stream.

Advanced Weathervaning in Ice

2011 ◽  
Author(s):  
William Hidding ◽  
Guillaume Bonnaffoux ◽  
Mamoun Naciri
Keyword(s):  
Rapid Change ◽  
Ice Sheet ◽  
Model Tests ◽  
The Arctic ◽  
Mooring System ◽  
Sudden Increase ◽  
Time Step ◽  
Ice Loads ◽  
Level Ice ◽  
Drift Direction

The reported presence of one third of remaining fossil reserves in the Arctic has sparked a lot of interest from energy companies. This has raised the necessity of developing specific engineering tools to design safely and accurately arctic-compliant offshore structures. The mooring system design of a turret-moored vessel in ice-infested waters is a clear example of such a key engineering tool. In the arctic region, a turret-moored vessel shall be designed to face many ice features: level ice, ice ridges or even icebergs. Regarding specifically level ice, a turret-moored vessel will tend to align her heading (to weather vane) with the ice sheet drift direction in order to decrease the mooring loads applied by this ice sheet. For a vessel already embedded in an ice sheet, a rapid change in the ice drift direction will suddenly increase the ice loads before the weathervaning occurs. This sudden increase in mooring loads may be a governing event for the turret-mooring system and should therefore be understood and simulated properly to ensure a safe design. The paper presents ADWICE (Advanced Weathervaning in ICE), an engineering tool dedicated to the calculation of the weathervaning of ship-shaped vessels in level ice. In ADWICE, the ice load formulation relies on the Croasdale model. Ice loads are calculated and applied to the vessel quasi-statically at each time step. The software also updates the hull waterline contour at each time step in order to calculate precisely the locations of contact between the hull and the ice sheet. Model tests of a turret-moored vessel have been performed in an ice basin. Validation of the simulated response is performed by comparison with model tests results in terms of weathervaning time, maximum mooring loads, and vessel motions.

Early Holocene ocean conditions off the Zachariæ Isstrøm, Northeast Greenland

2021 ◽  
Author(s):  
Joanna Davies ◽  
Anders Møller Mathiasen ◽  
Kristiane Kristensen ◽  
Christof Pearce ◽  
Marit-Solveig Seidenkrantz
Keyword(s):  
Climate Change ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Atlantic Water ◽  
The Arctic ◽  
Future Climate Change ◽  
Polar Regions ◽  
Ice Shelf ◽  
Outlet Glacier ◽  
The Impact

&lt;p&gt;The polar regions exhibit some of the most visible signs of climate change globally; annual mass loss from the Greenland Ice Sheet (GrIS) has quadrupled in recent decades, from 51 &amp;#177; 65 Gt yr&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; (1992-2001) to 211 &amp;#177; 37 Gt yr&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; (2002-2011). This can partly be attributed to the widespread retreat and speed-up of marine-terminating glaciers. The Zachariae Isstr&amp;#248;m (ZI) is an outlet glacier of the Northeast Greenland Ice Steam (NEGIS), one of the largest ice streams of the GrIS (700km), draining approximately 12% of the ice sheet interior. Observations show that the ZI began accelerating in 2000, resulting in the collapse of the floating ice shelf between 2002 and 2003. By 2014, the ice shelf extended over an area of 52km&lt;sup&gt;2&lt;/sup&gt;, a 95% decrease in area since 2002, where it extended over 1040km&lt;sup&gt;2&lt;/sup&gt;. Paleo-reconstructions provide an opportunity to extend observational records in order to understand the oceanic and climatic processes governing the position of the grounding zone of marine terminating glaciers and the extent of floating ice shelves. Such datasets are thus necessary if we are to constrain the impact of future climate change projections on the Arctic cryosphere.&lt;/p&gt;&lt;p&gt;A multi-proxy approach, involving grain size, geochemical, foraminiferal and sedimentary analysis was applied to marine sediment core DA17-NG-ST8-92G, collected offshore of the ZI, on &amp;#160;the Northeast Greenland Shelf. The aim was to reconstruct changes in the extent of the ZI and the palaeoceanographic conditions throughout the Early to Mid Holocene (c.a. 12,500-5,000 cal. yrs. BP). Evidence from the analysis of these datasets indicates that whilst there has been no grounded ice at the site over the last 12,500 years, the ice shelf of the ZI extended as a floating ice shelf over the site between 12,500 and 9,200 cal. yrs. BP, with the grounding line further inland from our study site. This was followed by a retreat in the ice shelf extent during the Holocene Thermal Maximum; this was likely to have been governed, in part, by basal melting driven by Atlantic Water (AW) recirculated from Svalbard or from the Arctic Ocean. Evidence from benthic foraminifera suggest that there was a shift from the dominance of AW to Polar Water at around 7,500 cal. yrs. BP, although the ice shelf did not expand again despite of this cooling of subsurface waters.&lt;/p&gt;

Natural variability and recent warming in central Greenland ice cores

2021 ◽  
Author(s):  
Maria Hoerhold ◽  
Thomas Münch ◽  
Stefanie Weißbach ◽  
Sepp Kipfstuhl ◽  
Bo Vinther ◽  
...  
Keyword(s):  
Climate Variability ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Cores ◽  
Natural Variability ◽  
The Arctic ◽  
Last Millennium ◽  
Recent Warming ◽  
Temperature Reconstructions ◽  
Firn Core

&lt;p&gt;Climate variability of the Arctic region has been investigated by means of temperature reconstructions based on proxies from various climate archives around the Arctic, compiled over the last 2000a in the so called Arctic2k record. However, the representativeness of the Arctic2k reconstruction for central Greenland remains unclear, since only a few ice cores have been included in the reconstruction, and observations from the Greenland Ice Sheet (GIC) report ambiguous warming trends for the end of the 20th and the beginning of the 21st century which are not displayed by Arctic2k. Today, the GIC experiences periods with temperatures close to or above the freezing point at high elevations, area-wide melting and mass loss. In order to assess the recent warming as signature of global climate change, records of past climate changes with appropriate temporal and spatial coverage can serve as a benchmark for naturally driven climate variability. Instrumental records for Greenland are short and geographically sparse, and existing temperature reconstructions from single ice cores are noisy, leading to an inconclusive assessment of the recent warming for Greenland.&lt;/p&gt;&lt;p&gt;Here, we provide a Greenland firn-core stack covering the time span of the last millennium until the first decade of the 21&lt;sup&gt;st &lt;/sup&gt;century in unprecedented quality by re-drilling as well as analyzing 16 existing firn core sites. We find a strong decadal to bi-decadal natural variability in the record, and, while the record exhibits several warming events with trends that show a similar amplitude as the recent one, we find that the recent absolute values of stable oxygen isotope composition are unprecedented for the last 1000 years.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Comparing our Greenland record with the Arctic 2k temperature reconstruction shows that the correlation between the two records changes throughout the last millennium. While in the periods of 1200-1300 and 1400-1650 CE the records correlate positively, between 1300 and 1400 and 1650-1700 CE shorter periods with negative correlation are found. Since then the correlation is characterized by alternation between positive and zero correlation, with a drop towards negative values at the end of the 20&lt;sup&gt;th&lt;/sup&gt; century. Including re-analysis data, we hypothesize that the climate on top of the GIC was decoupled from the surrounding Arctic for the last decades, leading to the observed mismatch in observations of warming trends.&lt;/p&gt;&lt;p&gt;We suggest that the recently observed Greenland temperatures are a superposition of a strong natural variability with an anthropogenic long-term trend. Our findings illustrate that global warming has reached the interior of the Greenland ice sheet, which will have implications for its surface mass balance and Greenland&amp;#8217;s future contribution to sea level rise.&lt;/p&gt;&lt;p&gt;Our record complements the Arctic 2k record to a profound view on the Arctic climate variability, where regional compilations may not be representative for specific areas.&lt;/p&gt;

scholarly journals Contribution to the Movement and the form of Ice Sheets in the Arctic and Antarctic

1961 ◽  
Vol 3 (30) ◽  
pp. 1133-1151 ◽  
Author(s):  
R. Haefeli
Keyword(s):  
Average Rate ◽  
Ice Sheet ◽  
Surface Profile ◽  
Greenland Ice Sheet ◽  
Present Theory ◽  
The Arctic ◽  
Small Influence ◽  
Horizontal Velocity Component ◽  
Flow Law ◽  
Set Up

AbstractStarting from Glen’s flow law for ice and from a series of assumptions based in part on observations in Greenland and in the Jungfraujoch, the velocity distribution (horizontal velocity component) and surface configuration is derived for a strip-shaped ice sheet in a stationary state. For the choice n = 3 − 4 of the exponent in the power-law flow relation, there is extensive agreement between the theoretically calculated surface profile and the east-west profile measured through “Station Centrale” by Expéditions Polaires Françaises. The corresponding theoretical solution for a circular ice sheet is also given. As a first application of this theory, an attempt is made to calculate the average rate of accumulation in Antarctica from its surface profile (assumed circular in plan) and from the flow-law parameters derived from the Greenland Ice Sheet. It is also shown that a change in accumulation has only a small influence on the total ice thickness of an ice sheet. A method of calculating approximately the age of ice in an ice sheet, based on the foregoing theory, is illustrated by applying it to the Greenland Ice Sheet. After comparing the present theory with that of Nye, a general expression for the surface profile of an ice sheet with constant accumulation is set up and discussed by means of comparison with two profiles through Antarctica.

scholarly journals Sodankylä manual snow survey program

2016 ◽  
Vol 5 (1) ◽  
pp. 163-179 ◽  
Author(s):  
Leena Leppänen ◽  
Anna Kontu ◽  
Henna-Reetta Hannula ◽  
Heidi Sjöblom ◽  
Jouni Pulliainen
Keyword(s):  
Snow Water Equivalent ◽  
Measurement Techniques ◽  
Liquid Water Content ◽  
The Arctic ◽  
Research Centre ◽  
Future Research ◽  
Forest Zone ◽  
Finnish Meteorological Institute ◽  
Snow Properties ◽  
Snow Water

Abstract. The manual snow survey program of the Arctic Research Centre of the Finnish Meteorological Institute (FMI-ARC) consists of numerous observations of natural seasonal taiga snowpack in Sodankylä, northern Finland. The easily accessible measurement areas represent the typical forest and soil types in the boreal forest zone. Systematic snow measurements began in 1909 with snow depth (HS) and snow water equivalent (SWE). In 2006 the manual snow survey program expanded to cover snow macro- and microstructure from regular snow pits at several sites using both traditional and novel measurement techniques. Present-day snow pit measurements include observations of HS, SWE, temperature, density, stratigraphy, grain size, specific surface area (SSA) and liquid water content (LWC). Regular snow pit measurements are performed weekly during the snow season. Extensive time series of manual snow measurements are important for the monitoring of temporal and spatial changes in seasonal snowpack. This snow survey program is an excellent base for the future research of snow properties.

scholarly journals Arabis alpina: a perennial model plant for ecological genomics and life-history evolution

2021 ◽  
Author(s):  
Stefan Wötzel ◽  
Marco Andrello ◽  
Maria Albani ◽  
Marcus Koch ◽  
George Coupland ◽  
...  
Keyword(s):  
Life History ◽  
Life History Evolution ◽  
The Arctic ◽  
Model Organisms ◽  
Future Research ◽  
Ecological Genomics ◽  
Open Questions ◽  
Arabis Alpina ◽  
History Evolution ◽  
Plant Families

Many model organisms have obtained a prominent status due to an advantageous combination of their life-history characteristics, genetic properties and also practical considerations. In non-crop plants, Arabidopsis thaliana is the most renowned model and has been used as study system to elucidate numerous biological processes at the molecular level. Once a complete genome sequence was available, research has markedly accelerated and further established A. thaliana as the reference to stimulate studies in other species with different biology. Within the Brassicaceae family, the arctic-alpine perennial Arabis alpina has become a model complementary to A. thaliana to study life-history evolution and ecological genomics in harsh environments. In this review, we provide an overview of the properties that facilitated the rapid emergence of A. alpina as a plant model. We summarize the evolutionary history of A. alpina, including the diversification of its mating system, and discuss recent progress in the molecular dissection of developmental traits that are related to its perennial life history and environmental adaptation. We indicate open questions from which future research might be developed in other Brassicaceae species or more distantly related plant families.

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