scholarly journals Past freeze and thaw cycling in the margin of the El'gygytgyn Crater deduced from a 141 m long permafrost record

2013 ◽  
Vol 9 (4) ◽  
pp. 3993-4034 ◽  
Author(s):  
G. Schwamborn ◽  
H. Meyer ◽  
L. Schirrmeister ◽  
G. Fedorov
Keyword(s):  
Lake Level ◽  
The Arctic ◽  
Ground Ice ◽  
Frozen Ground ◽  
Sediment Delivery ◽  
Near Surface ◽  
Lake Level Changes ◽  
Freeze And Thaw ◽  
Hydrochemical Composition ◽  
Core Depth

Abstract. Past permafrost thaw and freeze has destabilised the basin slopes of Lake El'gygytgyn in the northeastern Eurasian Arctic. This has probably promoted the release of mass movements from the lake edge to the deeper basin as known from frequently occurring turbidite layers in the lake sediment column. The continuous sediment record from the Arctic spans the last 3.6 Ma and for much of this time permafrost dynamics and lake level changes likely have played a crucial role for sediment delivery to the lake. Changes in the ground ice hydrochemical composition (pH, δ18O, δD, electrical conductivity, Na+, Mg2+, Ca2+, K+, HCO3−, Cl−, SO4−) of a 141 m long permafrost record from the western crater plain are examined to reconstruct repeated freeze and thaw cycles at the lake edge. Stable water isotope and major ion records of ground ice in the permafrost reflect both a synsedimentary palaeo-precipitation signal preserved in the near-surface permafrost (0.0 m to 9.1 m core depth) and a postdepositional record of talik thawing and refreezing in deeper layers of the core (9.1 to 141.0 m core depth). The lake marginal permafrost dynamics were controlled by lake level changes that episodically flooded the surfaces and induced thaw in the underlying frozen ground. At least three cycles of freeze and thaw during marine isotope stage (MIS) 7, possibly MIS 5, and the Allerød (AD) are identified and the hydrochemical data point to a vertical and horizontal talik refreezing through time.

scholarly journals Past freeze and thaw cycling in the margin of the El'gygytgyn crater deduced from a 141 m long permafrost record

2014 ◽  
Vol 10 (3) ◽  
pp. 1109-1123 ◽  
Author(s):  
G. Schwamborn ◽  
H. Meyer ◽  
L. Schirrmeister ◽  
G. Fedorov
Keyword(s):  
Lake Level ◽  
Ground Ice ◽  
Frozen Ground ◽  
Sediment Delivery ◽  
Near Surface ◽  
Lake Level Changes ◽  
Freeze And Thaw ◽  
Lake El’Gygytgyn ◽  
Hydrochemical Composition ◽  
Core Depth

Abstract. The continuous sediment record from Lake El'gygytgyn in the northeastern Eurasian Arctic spans the last 3.6 Ma and for much of this time permafrost dynamics and lake level changes have likely played a crucial role for sediment delivery to the lake. Changes in the ground-ice hydrochemical composition (δ18O, δD, pH, electrical conductivity, Na+, Mg2+, Ca2+, K+, HCO3-, Cl-, SO4-) of a 141 m long permafrost record from the western crater plain are examined to reconstruct repeated periods of freeze and thaw at the lake edge. Stable water isotope and major ion records of ground ice in the permafrost reflect both a synsedimentary palaeo-precipitation signal preserved in the near-surface permafrost (0.0–9.1 m core depth) and a post-depositional record of thawing and refreezing in deeper layers of the core (9.1–141.0 m core depth). These lake marginal permafrost dynamics were controlled by lake level changes that episodically flooded the surfaces and induced thaw in the underlying frozen ground. During times of lake level fall these layers froze over again. At least three cycles of freeze and thaw are identified and the hydrochemical data point to a vertical and horizontal talik refreezing through time. Past permafrost thaw and freeze may have destabilised the basin slopes of Lake El'gygytgyn and this has probably promoted the release of mass movements from the lake edge to the deeper basin as known from frequently occurring turbidite layers in the lake sediment column.

scholarly journals Geophysical imaging of permafrost in the SW Svalbard – the result of two high arctic expeditions to Spitsbergen

2020 ◽  
Author(s):  
Mariusz Majdanski ◽  
Artur Marciniak ◽  
Bartosz Owoc ◽  
Wojciech Dobiński ◽  
Tomasz Wawrzyniak ◽  
...  
Keyword(s):  
Surface Waves ◽  
Active Layer ◽  
High Arctic ◽  
The Arctic ◽  
Seismic Profiles ◽  
Frozen Ground ◽  
Near Surface ◽  
Seismic Processing ◽  
Reflection Seismic ◽  
Sea Coast

<p>The Arctic regions are the place of the fastest observed climate change. One of the indicators of such evolution are changes occurring in the glaciers and the subsurface in the permafrost. The active layer of the permafrost as the shallowest one is well measured by multiple geophysical techniques and in-situ measurements.</p><p>Two high arctic expeditions have been organized to use seismic methods to recognize the shape of the permafrost in two seasons: with the unfrozen ground (October 2017) and frozen ground (April 2018). Two seismic profiles have been designed to visualize the shape of permafrost between the sea coast and the slope of the mountain, and at the front of a retreating glacier. For measurements, a stand-alone seismic stations has been used with accelerated weight drop with in-house modifications and timing system. Seismic profiles were acquired in a time-lapse manner and were supported with GPR and ERT measurements, and continuous temperature monitoring in shallow boreholes.</p><p>Joint interpretation of seismic and auxiliary data using Multichannel analysis of surface waves, First arrival travel-time tomography and Reflection imaging show clear seasonal changes affecting the active layer where P-wave velocities are changing from 3500 to 5200 m/s. This confirms the laboratory measurements showing doubling the seismic velocity of water-filled high-porosity rocks when frozen. The same laboratory study shows significant (>10%) increase of velocity in frozen low porosity rocks, that should be easily visible in seismic.</p><p>In the reflection seismic processing, the most critical part was a detailed front mute to eliminate refracted arrivals spoiling wide-angle near-surface reflections. Those long offset refractions were however used to estimate near-surface velocities further used in reflection processing. In the reflection seismic image, a horizontal reflection was traced at the depth of 120 m at the sea coast deepening to the depth of 300 m near the mountain.</p><p>Additionally, an optimal set of seismic parameters has been established, clearly showing a significantly higher signal to noise ratio in case of frozen ground conditions even with the snow cover. Moreover, logistics in the frozen conditions are much easier and a lack of surface waves recorded in the snow buried geophones makes the seismic processing simpler.</p><p>Acknowledgements               </p><p>This research was funded by the National Science Centre, Poland (NCN) Grant UMO-2015/21/B/ST10/02509.</p>

Gradual and Abrupt Permafrost Thaw as Drivers of Rapid Geomorphic Change in Arctic Permafrost Regions

2020 ◽  
Author(s):  
Guido Grosse ◽  
Julia Boike ◽  
Louise Farquharson ◽  
Benjamin M. Jones ◽  
Moritz Langer ◽  
...  
Keyword(s):  
Large Scale ◽  
The Arctic ◽  
Ecosystem Change ◽  
Last Deglaciation ◽  
Ground Ice ◽  
Frozen Ground ◽  
Positive Feedbacks ◽  
Climate Conditions ◽  
Permafrost Thaw ◽  
Wide Range

<p>In this presentation, we will highlight some of the overarching geomorphic dynamics of gradual and abrupt permafrost thaw using examples from Siberia, Alaska, and Canada, their role in Arctic landscapes transitioning to a warmer world, and implications for the Earth System. Northern high latitude regions are particularly vulnerable to warming and changes in climatic patterns, which leads to the thaw of ice-rich permafrost across vast Arctic and sub-Arctic landscapes. Permafrost thaw and subsequent geomorphological change directly interact with hydrology, biogeochemistry, and biology and thus have been major agents of Arctic ecosystem change since the last deglaciation. The changes are also important contributors to cumulative impacts associated with historic and current development of the Arctic, including in association with infrastructure. Today, in a rapidly warming Arctic, permafrost thaw processes, both gradual and abrupt, are accelerating in a manner comparable to the Holocene Thermal Maximum. At the same time, other environmental forcing factors, such as wildfires, precipitation, and hydrological processes, are also changing, either further reinforcing thaw dynamics or enhancing drainage and stabilizing the ground. Many of the resulting gradual and abrupt thaw processes are non-linear. Their dynamics are still poorly understood and insufficiently quantified in large-scale models due to lacking or limited representation of water-ice phase transitions during freeze-thaw cycles, ground ice distribution and loss, and challenging implementation of sub-gridcell scale interactions between frozen ground and hydrology. Gradual thaw impacts are especially pronounced in regions with an abundance of ice wedge polygons, and include changes in microtopography and extensive ponding in natural landscapes and those adjacent to infrastructure, where soils are warmed due to increased dust, flooding, snowdrifts, and altered vegetation. Abrupt thaw processes such as thermokarst and thermo-erosion represent rapid dynamics that are widespread in Arctic lowlands but poorly represented in observations and models. Characteristic landforms that result from abrupt thaw include thermokarst lakes and basins, retrogressive thaw slumps, and steep coastal bluffs. These landscape changes may be triggered by climate-driven press disturbances such as sea ice loss or increases in precipitation, pulse disturbances such as wildfires, or by anthropogenic disturbances such as road construction. When loss of excess ground ice is involved, positive feedbacks can result in a decoupling of further geomorphological change from climate. Once initiated, this may lead to continued or even accelerated growth of such features under a wide range of climate conditions, including in the high Arctic. Most abrupt thaw processes produce lasting impacts on northern permafrost landscapes that are irreversible over millennial timescales and result in the short-term mobilization of large amounts of permafrost carbon that may further contribute to climate warming.</p>

scholarly journals A warm jet in a cold ocean

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jennifer A. MacKinnon ◽  
Harper L. Simmons ◽  
John Hargrove ◽  
Jim Thomson ◽  
Thomas Peacock ◽  
...  
Keyword(s):  
The Arctic ◽  
Bering Strait ◽  
Near Surface ◽  
Ice Melt ◽  
Beaufort Gyre ◽  
The Pacific ◽  
Climate Simulations ◽  
Initial Evolution ◽  
Forecast Models

AbstractUnprecedented quantities of heat are entering the Pacific sector of the Arctic Ocean through Bering Strait, particularly during summer months. Though some heat is lost to the atmosphere during autumn cooling, a significant fraction of the incoming warm, salty water subducts (dives beneath) below a cooler fresher layer of near-surface water, subsequently extending hundreds of kilometers into the Beaufort Gyre. Upward turbulent mixing of these sub-surface pockets of heat is likely accelerating sea ice melt in the region. This Pacific-origin water brings both heat and unique biogeochemical properties, contributing to a changing Arctic ecosystem. However, our ability to understand or forecast the role of this incoming water mass has been hampered by lack of understanding of the physical processes controlling subduction and evolution of this this warm water. Crucially, the processes seen here occur at small horizontal scales not resolved by regional forecast models or climate simulations; new parameterizations must be developed that accurately represent the physics. Here we present novel high resolution observations showing the detailed process of subduction and initial evolution of warm Pacific-origin water in the southern Beaufort Gyre.

Effective and Ecological Technologies of Application of Structured Materials for Roadbed in the Permafrost Regions

2018 ◽  
Vol 284 ◽  
pp. 950-955
Author(s):  
V.G. Merzlikin ◽  
G.I. Bolkina ◽  
L.N. Ignatova
Keyword(s):  
Thermal State ◽  
Toxic Waste ◽  
The Arctic ◽  
Radiative Heat Exchange ◽  
High Mountain ◽  
Frozen Ground ◽  
Structured Materials ◽  
Environmental Measures ◽  
Soil Foundation ◽  
Support Engineering

The work is devoted to effective and ecological technologies for the application of functional structured materials for roads, railways, airfields on permafrost with forced cooling of the sub-soil foundation. The physical and mathematical simulation of the thermal state of frozen ground with single and double-layer coatings was performed. The temperature profiles of a model combine roadbed on the longstanding permafrost have been calculated at winter conditions of the Northern Hemisphere. This roadbed include an upper surface coating with low thermal conductivity and high emissivity in the long-wavelength IR range at convective-radiative heat exchange. The second high-conductive subsurface coating is laid on the underlying sub-soil and ensures its cooling as the “heat pump”. The efficiency of the proposed technology of roadbed construction based on the use of non-toxic waste of numerous industrial productions. The carried out research will be in demand for the specialists of transport support, engineering glaciology, in the field of climatology, oceanology, construction, environmental measures, and also in the presentation of financial and economic forecasts of the prospects for the development of polar and subpolar regions, the Arctic and the Antarctic, and high-mountain.

scholarly journals Ground ice in the Northern Foothills, northern Victoria Land, Antarctica

2004 ◽  
Vol 39 ◽  
pp. 495-500 ◽  
Author(s):  
Mauro Guglielmin ◽  
Hugh M. French
Keyword(s):  
Oxygen Isotope ◽  
Ross Sea ◽  
Progress Report ◽  
Ground Ice ◽  
Lake Ice ◽  
Near Surface ◽  
Victoria Land ◽  
Different Types ◽  
Glacier Ice ◽  
Surface Ice

AbstractThis progress report classifies the different types of ground-ice bodies that occur in the Northern Foothills, northern Victoria Land, Antarctica. Oxygen isotope variations are presented, but interpretation is kept to a minimum pending further investigations. Surface ice, as distinct from moving glacier ice, occurs in the form of widespread buried (‘dead’) glacier ice lying beneath ablation (sublimation) till, together with perennial lake ice, snow banks and icing-blister ice.’Dry’ permafrost is uncommon, and interstitial ice is usually present at the base of the active layer and in the near-surface permafrost. This probably reflects the supply of moisture from the Ross Sea and limited sublimation under today’s climate. Intrusive ice occurs as layers within perennial lake-ice covers and gives rise to small icing blisters. Small ice wedges found beneath the furrows of high-centered polygons appear to agree with the model of sublimation-till development proposed by Marchant and others (2002).

scholarly journals An Evaluation of Surface Atmospheric Changes over the Arctic Ocean for 2000–09 Using Recent Reanalyses

2015 ◽  
Vol 19 (2) ◽  
pp. 1-18 ◽  
Author(s):  
Ayan H. Chaudhuri ◽  
Rui M. Ponte
Keyword(s):  
Arctic Ocean ◽  
Extreme Event ◽  
Longwave Radiation ◽  
Remotely Sensed ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
The Arctic ◽  
Near Surface ◽  
The Arctic Ocean ◽  
Ice Retreat

Abstract The authors examine five recent reanalysis products [NCEP Climate Forecast System Reanalysis (CFSR), Modern-Era Retrospective Analysis for Research and Applications (MERRA), Japanese 25-year Reanalysis Project (JRA-25), Interim ECMWF Re-Analysis (ERA-Interim), and Arctic System Reanalysis (ASR)] for 1) trends in near-surface radiation fluxes, air temperature, and humidity, which are important indicators of changes within the Arctic Ocean and also influence sea ice and ocean conditions, and 2) fidelity of these atmospheric fields and effects for an extreme event: namely, the 2007 ice retreat. An analysis of trends over the Arctic for the past decade (2000–09) shows that reanalysis solutions have large spreads, particularly for downwelling shortwave radiation. In many cases, the differences in significant trends between the five reanalysis products are comparable to the estimated trend within a particular product. These discrepancies make it difficult to establish a consensus on likely changes occurring in the Arctic solely based on results from reanalyses fields. Regarding the 2007 ice retreat event, comparisons with remotely sensed estimates of downwelling radiation observations against these reanalysis products present an ambiguity. Remotely sensed observations from a study cited herewith suggest a large increase in downwelling summertime shortwave radiation and decrease in downwelling summertime longwave radiation from 2006 and 2007. On the contrary, the reanalysis products show only small gains in summertime shortwave radiation, if any; however, all the products show increases in downwelling longwave radiation. Thus, agreement within reanalysis fields needs to be further checked against observations to assess possible biases common to all products.

scholarly journals Mapping the Distribution of Buried Glacier Ice – An Example From Lago Delle Locce, Monte Rosa, Italian Alps

1986 ◽  
Vol 8 ◽  
pp. 78-81 ◽  
Author(s):  
W. Haeberli ◽  
F. Epifani
Keyword(s):  
Snow Cover ◽  
Seismic Refraction ◽  
Italian Alps ◽  
Frozen Ground ◽  
Near Surface ◽  
Winter Snow ◽  
Glacier Ice ◽  
Geoelectrical Resistivity ◽  
Monte Rosa

Techniques for mapping the distribution of buried glacier ice are discussed and the results, from a study carried out within the framework of flood protection work in the Italian Alps, are presented. Bottom temperatures of the winter snow cover (BTS) primarily indicate the heat flow conditions in the underlying ground and mainly depend on the presence or absence of an ice layer beneath the surface. Determination of BTS values is therefore an inexpensive method for quickly mapping the near-surface underground ice in areas where there is 1 m or more of winter snow cover. At greater depths, and/or when more detail is required, geoelectrical resistivity soundings and seismic refraction soundings are most commonly used to investigate underground ice. A combination of the two sounding techniques allows the vertical extent and the main characteristics (frozen ground, dead glacier ice) to be determined in at least a semi-quantitative way. Complications mainly arise from irregularity in the horizontal extension of the studied underground ice bodies, and they may have to be overcome by expensive core drillings and borehole measurements. Widespread occurrence of buried glacier ice was observed in morainic deposits, surrounding an ice-dammed lake near Macugnaga, Italy.

scholarly journals Numerical investigation of the Arctic ice-ocean boundary layer; implications for air-sea gas fluxes

2016 ◽  
Author(s):  
A. Bigdeli ◽  
B. Loose ◽  
S. T. Cole
Keyword(s):  
Sea Ice ◽  
Water Column ◽  
Mixed Layer ◽  
Mixed Layer Depth ◽  
The Arctic ◽  
Layer Depth ◽  
Near Surface ◽  
Resolution Model ◽  
Simplifying Assumptions ◽  
Vertical Spacing

Abstract. In ice-covered regions it can be challenging to determine air-sea exchange – for heat and momentum, but also for gases like carbon dioxide and methane. The harsh environment and relative data scarcity make it difficult to characterize even the physical properties of the ocean surface. Here, we seek a mechanistic interpretation for the rate of air-sea gas exchange (k) derived from radon-deficits. These require an estimate of the water column history extending 30 days prior to sampling. We used coarse resolution (36 km) regional configuration of the MITgcm with fine near surface vertical spacing (2 m) to evaluate the capability of the model to reproduce conditions prior to sampling. The model is used to estimate sea-ice velocity, concentration and mixed-layer depth experienced by the water column. We then compared the model results to existing field data including satellite, moorings and Ice-tethered profilers. We found that model-derived sea-ice coverage is 88 to 98 % accurate averaged over Beaufort Gyre, sea-ice velocities have 78 % correlation which resulted in 2 km/day error in 30 day trajectory of sea-ice. The model demonstrated the capacity to capture the broad trends in the mixed layer although with a bias and model water velocities showed only 29 % correlation with actual data. Overall, we find the course resolution model to be an inadequate surrogate for sparse data, however the simulation results are a slight improvement over several of the simplifying assumptions that are often made when surface ocean geochemistry, including the use of a constant mixed layer depth and a velocity profile that is purely wind-driven.

scholarly journals Tropospheric BrO column densities in the Arctic derived from satellite: retrieval and comparison to ground-based measurements

2012 ◽  
Vol 5 (11) ◽  
pp. 2779-2807 ◽  
Author(s):  
H. Sihler ◽  
U. Platt ◽  
S. Beirle ◽  
T. Marbach ◽  
S. Kühl ◽  
...  
Keyword(s):  
Boundary Layer ◽  
The Arctic ◽  
Trace Gas ◽  
Natural Phenomenon ◽  
Satellite Measurements ◽  
Surface Layers ◽  
Vertical Column ◽  
Near Surface ◽  
The Vertical Distribution ◽  
Good Agreement

Abstract. During polar spring, halogen radicals like bromine monoxide (BrO) play an important role in the chemistry of tropospheric ozone destruction. Satellite measurements of the BrO distribution have become a particularly useful tool to investigate this probably natural phenomenon, but the separation of stratospheric and tropospheric partial columns of BrO is challenging. In this study, an algorithm was developed to retrieve tropospheric vertical column densities of BrO from data of high-resolution spectroscopic satellite instruments such as the second Global Ozone Monitoring Experiment (GOME-2). Unlike recently published approaches, the presented algorithm is capable of separating the fraction of BrO in the activated troposphere from the total BrO column solely based on remotely measured properties. The presented algorithm furthermore allows to estimate a realistic measurement error of the tropospheric BrO column. The sensitivity of each satellite pixel to BrO in the boundary layer is quantified using the measured UV radiance and the column density of the oxygen collision complex O4. A comparison of the sensitivities with CALIPSO LIDAR observations demonstrates that clouds shielding near-surface trace-gas columns can be reliably detected even over ice and snow. Retrieved tropospheric BrO columns are then compared to ground-based BrO measurements from two Arctic field campaigns in the Amundsen Gulf and at Barrow in 2008 and 2009, respectively. Our algorithm was found to be capable of retrieving enhanced near-surface BrO during both campaigns in good agreement with ground-based data. Some differences between ground-based and satellite measurements observed at Barrow can be explained by both elevated and shallow surface layers of BrO. The observations strongly suggest that surface release processes are the dominating source of BrO and that boundary layer meteorology influences the vertical distribution.

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