scholarly journals Quantitative and qualitative constraints on hind-casting the formation of multiyear lake-ice covers at Lake El'gygytgyn

2013 ◽  
Vol 9 (3) ◽  
pp. 1253-1269 ◽  
Author(s):  
M. Nolan
Keyword(s):  
Water Exchange ◽  
Sediment Cores ◽  
Ice Cover ◽  
Lake Ice ◽  
Ice Growth ◽  
Temperature Reduction ◽  
Air Temperatures ◽  
Lake El’Gygytgyn ◽  
Oxygen Conditions ◽  
Multiyear Ice

Abstract. Analysis of the 3.6 Ma, 318 m long sediment core from Lake El'gygytgyn suggests that the lake was covered by ice for millennia at a time for much of its history and therefore this paper uses a suite of existing, simple, empirical degree-day models of lake-ice growth and decay to place quantitative constraints on air temperatures needed to maintain a permanent ice cover on the lake. We also provide an overview of the modern climatological and physical processes that relate to lake-ice growth and decay as a basis for evaluating past climate and environmental conditions. Our modeling results indicate that modern annual mean air temperature would only have to be reduced by 3.3 °C ± 0.9 °C to initiate a multiyear ice cover and a temperature reduction of at least 5.5 °C ± 1.0 °C is likely needed to completely eliminate direct air–water exchange of oxygen, conditions that have been inferred at Lake El'gygytgyn from the analysis of sediment cores. Once formed, a temperature reduction of only 1–3 °C relative to modern may be all that is required to maintain multiyear ice. We also found that formation of multiyear ice covers requires that positive degree days are reduced by about half the modern mean, from about +608 to +322. A multiyear ice cover can persist even with summer temperatures sufficient for a two-month long thawing period, including a month above +4 °C. Thus, it is likely that many summer biological processes and some lake-water warming and mixing may still occur beneath multiyear ice-covers even if air–water exchange of oxygen is severely restricted.

scholarly journals Analysis of local AWS and NCEP/NCAR reanalysis data at Lake El'gygtytgyn, and its implications for maintaining multi-year lake-ice covers

2012 ◽  
Vol 8 (2) ◽  
pp. 1443-1483 ◽  
Author(s):  
M. Nolan
Keyword(s):  
Full Range ◽  
Summer Rainfall ◽  
Barometric Pressure ◽  
Ice Cover ◽  
Warming Trend ◽  
Reanalysis Data ◽  
Lake Ice ◽  
Ice Dynamics ◽  
Air Temperatures ◽  
Perennial Ice

Abstract. We compared 7 years of local automated weather station (AWS) data to NCEP/NCAR reanalysis data to characterize the modern environment of Lake El'gygytgyn, in Chukotka Russia. We then used this comparison to estimate the air temperatures required to initiate and maintain multi-year lake-ice covers to aid in paleoclimate reconstructions of the 3.6 M years sediment record recovered from there. We present and describe data from our AWS from 2002–2008, which recorded air temperatures, relative humidity, precipitation, barometric pressure, and wind speed/direction, as well as subsurface soil moisture and temperature. Measured mean annual air temperature (MAAT) over this period was −10.4 °C with a slight warming trend during the measurement period. NCEP/NCAR reanalysis air temperatures compared well to this, with annual means within 0.1 to 2.0 °C of the AWS, with an overall mean 1.1 °C higher than the AWS, and daily temperature trends having a correlation of over 96% and capturing the full range of variation. After correcting for elevation differences, barometric pressure discrepancies occasionally reached as high as 20 mbar higher than the AWS particularly in winter, but the correlation in trends was high at 92%, indicating that synoptic-scale weather patterns driving local weather likely are being captured by the reanalysis data. AWS cumulative summer rainfall measurements ranged between 70–200 mm during the record. NCEP/NCAR reanalysis precipitation failed to predict daily events measured by the AWS, but largely captured the annual trends, though higher by a factor of 2–4. NCEP air temperatures showed a strong trend in MAAT over the 1961–2009 record, rising from a pre-1995 mean of −12.0 °C to a post-1994 mean of −9.8 °C. We found that nearly all of this change could be explained by changes in winter temperatures, with mean winter degree days (DD) rising from −5043 to −4340 after 1994 and a much smaller change in summer DD from +666 to +700. Thus, the NCEP record indicates that nearly all modern change in MAAT is driven by changes in winter (which promotes lake-ice growth) not summer (which promotes lake-ice melt). Whether this sensitivity is representative of paleo-conditions is unclear, but it is clear that the lake was unlikely to have initiated a multi-year ice cover since 1961 based on simple DD models of ice dynamics. Using these models we found that the NCEP/NCAR reanalysis mean MAAT over 1961–2009 would have to be at least 4 °C colder to initiate a multi-year ice cover, but more importantly that multi-year ice covers are largely controlled by summer melt rates at this location. Specifically we found that summer DD would have to drop by more than half the modern mean, from +640 to +280. Given that the reanalysis temperatures appears about 1 °C higher than reality, a MAAT cooling of 3 °C may be sufficient in the real world, but as described in the text we consider a cooling of −4°C ± 0.5 °C a reasonable requirement for multi-year ice covers. Also perhaps relevant to paleo-climate proxy interpretation, at temperatures cold enough to maintain a multi-year ice cover, the summer temperatures could still be sufficient for a two-month long thawing period, including a month at about +5 °C Thus it is likely that many summer biological processes and some lake-water warming and mixing may still have been occurring beneath perennial ice-covers; core proxies have already indicated that such perennial ice-covers may have persisted for tens of thousands of years at various times within the 3.6 M years record.

scholarly journals Air Bubble Stratigraphy of Lake Ice Covers

1983 ◽  
Vol 4 ◽  
pp. 299
Author(s):  
Richard Heron
Keyword(s):  
Bubble Formation ◽  
Ice Cover ◽  
Air Bubbles ◽  
Lake Ice ◽  
Daily Growth ◽  
Local Conditions ◽  
Small Lake ◽  
Ice Growth ◽  
Bubble Characteristics ◽  
Bubble Layers

Lake ice often has inclusions of air bubbles and their presence affects the thermal, mechanical, optical and other physical properties of the ice cover. Vertical variation in the characteristics of the bubbles suggests that their characteristics should be related to the rate of ice growth at the time of formation and therefore reflect past meteorological conditions.The laboratory studies of Carte (1961) and Bari and Hallett (1974) demonstrated that the rate of ice growth affects the size, shape and distribution of bubbles and the porosity of the ice. Their results were generally supported by the field study of Gow and Langston (1977), but Swinzow (1966) found no relationship between bubble characteristics and the rate of ice growth.Freeze-up and initial ice growth were monitored at Small Lake, Resolute, NWT, Canada, in 1978 to determine what diagnostic information night he obtained fror,) the inclusion stratigraphy of the ice cover. Additional samples were collected from five other lakes in the Resolute area, a shallow lake near Hamilton, Ontario, and two lakes near Huntsville, Ontario. Daily ice samples were removed from the ice cover of Small Lake and the inclusion stratigraphy was mapped. A typical ice sample shows diurnal sequences of bubbly and bubble-free ice. The inclusion layers, 1 to 5 mm thick, were formed near midday and were separated by 10 to 15 mm of clear, bubble-free ice. All samples were missing at least one inclusion stratum. There was a wide variety of bubble types and sizes, and non-gaseous inclusions, believed to be algae, were noted in some of the bubble layers. The hourly rate of ice growth was calculated using a modified Stefan equation. No relationship between the bubble characteristics and the rate of ice growth was obtained. The influence of the algae and the absorption of solar radiation by the water are probably responsible for the diurnal cycle of bubble formation by influencing nucleation. The absorbed radiation will warm the water and decrease the amount of air that the water can dissolve, thus making more air available for bubble growth. The algae will also change the concentrations of dissolved gases and act as nucleating agents.Cores taken from Small Lake in spring showed large cylindrical bubbles in the lower meter of the ice cover which had a thickness of 2.4 m. An inverse relationship between porosity and rate of ice growth was observed for these bubbles.Ice samples taken from the other lakes in the Resolute area either showed no inclusions at all or exhibited fewer diurnal inclusion sequences. Using a general bubble stratigraphy obtained from Small Lake it is possible to correlate some inclusion layers in samples taken from lakes that are 15 km apart.The samples from Hamilton also showed diurnal stratigraphie sequences except that the spacing between the bubble layers was more variable due to a larger range of daily growth rates. However, the two lakes near Huntsville had a detailed bubble stratigraphy, with little clear ice and no evidence of diurnal variation. The bubble layers in the ice from the two lakes could be easily matched, although they are 15 km apart.This study shows that bubble layers formed in a growing ice cover may be used to reveal some aspects of the history of the growth of the ice cover, although the applicability depends greatly on local conditions. Additional studies are required to understand the mechanisms by which air bubbles and algae are incorporated into lake ice.

scholarly journals Late Quaternary lake-level changes of Lake El'gygytgyn, NE Siberia

2011 ◽  
Vol 76 (3) ◽  
pp. 441-451 ◽  
Author(s):  
Olaf Juschus ◽  
Maksim Pavlov ◽  
Georg Schwamborn ◽  
Frank Preusser ◽  
Grigory Fedorov ◽  
...  
Keyword(s):  
Water Level ◽  
Lake Level ◽  
Late Quaternary ◽  
Sediment Cores ◽  
Lake Ice ◽  
Oxygen Isotope Stage ◽  
Northeastern Siberia ◽  
Lake El’Gygytgyn ◽  
High Lake Level ◽  
High Lake Levels

AbstractLake El'gygytgyn is situated in a 3.6 Ma old impact crater in northeastern Siberia. Presented here is a reconstruction of the Quaternary lake-level history as derived from sediment cores from the southern lake shelf. There, a cliff-like bench 10 m below the modern water level has been investigated. Deep-water sediments on the shelf indicate high lake levels during a warm Mid-Pleistocene period. One period with low lake level prior to Marine Oxygen Isotope Stage (MIS) 3 has been identified, followed by a period of high lake level (10 m above present). In the course of MIS 2 the lake level dropped to − 10 m. At the end of MIS 2 the bench was formed and coarse beach sedimentation occurred. Subsequently, the lake level rose rapidly to the Holocene level. Changes in water level are likely linked to climate variability. During relatively temperate periods the lake becomes free of ice in summer. Strong wave actions transport sediment parallel to the coast and towards the outlet, where the material tends to accumulate, resulting in lake level rise. During cold periods the perennial lake ice cover hampers any wave activity and pebble-transport, keeping the outlet open and causing the lake level to drop.

scholarly journals Air Bubble Stratigraphy of Lake Ice Covers

1983 ◽  
Vol 4 ◽  
pp. 299-299
Author(s):  
Richard Heron
Keyword(s):  
Bubble Formation ◽  
Ice Cover ◽  
Air Bubbles ◽  
Lake Ice ◽  
Daily Growth ◽  
Local Conditions ◽  
Small Lake ◽  
Ice Growth ◽  
Bubble Characteristics ◽  
Bubble Layers

Lake ice often has inclusions of air bubbles and their presence affects the thermal, mechanical, optical and other physical properties of the ice cover. Vertical variation in the characteristics of the bubbles suggests that their characteristics should be related to the rate of ice growth at the time of formation and therefore reflect past meteorological conditions.The laboratory studies of Carte (1961) and Bari and Hallett (1974) demonstrated that the rate of ice growth affects the size, shape and distribution of bubbles and the porosity of the ice. Their results were generally supported by the field study of Gow and Langston (1977), but Swinzow (1966) found no relationship between bubble characteristics and the rate of ice growth.Freeze-up and initial ice growth were monitored at Small Lake, Resolute, NWT, Canada, in 1978 to determine what diagnostic information night he obtained fror,) the inclusion stratigraphy of the ice cover. Additional samples were collected from five other lakes in the Resolute area, a shallow lake near Hamilton, Ontario, and two lakes near Huntsville, Ontario. Daily ice samples were removed from the ice cover of Small Lake and the inclusion stratigraphy was mapped. A typical ice sample shows diurnal sequences of bubbly and bubble-free ice. The inclusion layers, 1 to 5 mm thick, were formed near midday and were separated by 10 to 15 mm of clear, bubble-free ice. All samples were missing at least one inclusion stratum. There was a wide variety of bubble types and sizes, and non-gaseous inclusions, believed to be algae, were noted in some of the bubble layers. The hourly rate of ice growth was calculated using a modified Stefan equation. No relationship between the bubble characteristics and the rate of ice growth was obtained. The influence of the algae and the absorption of solar radiation by the water are probably responsible for the diurnal cycle of bubble formation by influencing nucleation. The absorbed radiation will warm the water and decrease the amount of air that the water can dissolve, thus making more air available for bubble growth. The algae will also change the concentrations of dissolved gases and act as nucleating agents.Cores taken from Small Lake in spring showed large cylindrical bubbles in the lower meter of the ice cover which had a thickness of 2.4 m. An inverse relationship between porosity and rate of ice growth was observed for these bubbles.Ice samples taken from the other lakes in the Resolute area either showed no inclusions at all or exhibited fewer diurnal inclusion sequences. Using a general bubble stratigraphy obtained from Small Lake it is possible to correlate some inclusion layers in samples taken from lakes that are 15 km apart.The samples from Hamilton also showed diurnal stratigraphie sequences except that the spacing between the bubble layers was more variable due to a larger range of daily growth rates. However, the two lakes near Huntsville had a detailed bubble stratigraphy, with little clear ice and no evidence of diurnal variation. The bubble layers in the ice from the two lakes could be easily matched, although they are 15 km apart.This study shows that bubble layers formed in a growing ice cover may be used to reveal some aspects of the history of the growth of the ice cover, although the applicability depends greatly on local conditions. Additional studies are required to understand the mechanisms by which air bubbles and algae are incorporated into lake ice.

scholarly journals Terms and conditions of high-mountain lake ice-cover chemistry (Carpathians, Poland)

2015 ◽  
Vol 61 (230) ◽  
pp. 1207-1212 ◽  
Author(s):  
Iwona Kurzyca ◽  
Adam Choiński ◽  
Joanna Pociask-Karteczka ◽  
Agnieszka Lawniczak ◽  
Marcin Frankowski
Keyword(s):  
Water Body ◽  
Ice Cover ◽  
Multilayered Structure ◽  
Mountain Lake ◽  
High Mountain ◽  
Lake Ice ◽  
High Mountain Lake ◽  
Spatial Diversification ◽  
The Tatra Mountains

AbstractWe discuss the results of an investigation of the chemical composition of the ice cover on the high-mountain lake Morskie Oko in the Tatra Mountains, Carpathians, Poland. In the years 2007–13, the ice cover was characterized by an average duration of 6 months, a thickness range of 0.40–1.14 m, and a multilayered structure with water or slush inclusion. In water from the melted ice cover, chloride (max. 69%) and sulphate (max. 51%) anions and ammonium (max. 66%) and calcium (max. 78%) cations predominated. Different concentrations of ions (F−, Cl−, NO3−, SO42−, Na+, K+, Mg2+, Ca2+, NH4+) in the upper, middle and bottom layers of ice were observed, along with long-term variability and spatial diversification within the ice layer over the lake. Snowpack lying on the ice and the water body under the ice were also investigated, and the influence on the ice cover of certain ions in elevated concentrations was observed (e.g. Cl− in the upper ice cover and the snowpack, and Ca2+ in the bottom ice cover and water body).

Increasing Multiyear Sea Ice Loss in the Beaufort Sea: A New Export Pathway for the Diminishing Multiyear Ice Cover of the Arctic Ocean

2021 ◽  
Author(s):  
David Gareth Babb ◽  
Ryan J. Galley ◽  
Stephen E. L. Howell ◽  
Jack Christopher Landy ◽  
Julienne Christine Stroeve ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Beaufort Sea ◽  
Ice Cover ◽  
The Arctic ◽  
Export Pathway ◽  
The Arctic Ocean ◽  
Multiyear Ice

Remote sensing of multiyear ice in the Antarctic

2021 ◽  
Author(s):  
Christian Melsheimer ◽  
Gunnar Spreen
Keyword(s):  
Time Series ◽  
Sea Ice ◽  
Global Climate ◽  
Ice Cover ◽  
Cold Season ◽  
Arctic Sea Ice ◽  
Weddell Sea ◽  
Detailed Knowledge ◽  
The Antarctic ◽  
Multiyear Ice

<p>The changing sea ice cover of polar seas is of key importance for the exchange of heat and moisture between atmosphere and ocean and hence for weather and climate, and in addition, the sea ice and its long-term changes are  an indicator for global change.  In order to properly understand and model the evolution of the sea ice cover and its interaction with the global climate system, we need detailed knowledge about sea ice, i.e., not only its extent, but also, e.g., its thickness and its type.</p> <p>We can broadly distinguish a few different sea ice types that have different dynamic and thermodynamic properties, namely: young ice (YI, thin/smooth new ice), first-year ice (FYI, formed during one cold season), and multiyear ice (MYI, which has survived at least one melt season). The  latter is of particular interest as it is usually thicker than other ice types (thus, takes more time to melt), much less saline, and may accommodate a unique ecosystem. Sea ice types in the Antarctic, until recently, have not been monitored much because of the lack of appropriate remote  sensing methods. While the Antarctic sea ice is greatly dominated by FYI, there are, nevertheless, considerable amounts of MYI, in particular in the Weddell Sea.</p> <p>We have recently adapted an algorithm for the detection of Arctic sea ice types for application in the Antarctic. The algorithm uses data from space-borne microwave radiometers and scatterometers as input. So far we have compiled a time series of daily Antarctic MYI data (and also an estimate of YI and FYI) data at a spatial resolution of 12.5 km, starting in 2013, but excluding the melt seasons when the algorithm does not work. Here give an overview of the data, showing, e.g., the quite large interannual variability of MYI and its evolution in the Weddell Sea, and discuss shortcomings of the algorithm and possible ways forward. The time series of daily Antarctic MYI data can in principle be extended backwards to the year 2000, when the used satellite data first became available, and with planned future satellite missions, it can be continued for years to come.</p>

scholarly journals Contrasting the ecological effects of decreasing ice cover versus accelerated glacial melt on the High Arctic's largest lake

2020 ◽  
Vol 287 (1929) ◽  
pp. 20201185
Author(s):  
Neal Michelutti ◽  
Marianne S. V. Douglas ◽  
Dermot Antoniades ◽  
Igor Lehnherr ◽  
Vincent L. St. Louis ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Fold Increase ◽  
Mass Gain ◽  
Ecological Change ◽  
Diatom Assemblages ◽  
Lake Ice ◽  
Glacial Meltwater ◽  
Glacial Runoff ◽  
Common Era ◽  
Ecological Functioning

Lake Hazen, the High Arctic's largest lake, has received an approximately 10-fold increase in glacial meltwater since its catchment glaciers shifted from net mass gain to net mass loss in 2007 common era (CE), concurrent with recent warming. Increased glacial meltwater can alter the ecological functioning of recipient aquatic ecosystems via changes to nutrient budgets, turbidity and thermal regimes. Here, we examine a rare set of five high-resolution sediment cores collected in Lake Hazen between 1990 and 2017 CE to investigate the influence of increased glacial meltwater versus alterations to lake ice phenology on ecological change. Subfossil diatom assemblages in all cores show two major shifts over the past approximately 200 years including: (i) a proliferation of pioneering, benthic taxa at approximately 1900 CE from previously depauperate populations; and (ii) a rise in planktonic taxa beginning at approximately 1980 CE to present-day dominance. The topmost intervals from each sequentially collected core provide exact dates and demonstrate that diatom regime shifts occurred decades prior to accelerated glacial inputs. These data show that diatom assemblages in Lake Hazen are responding primarily to intrinsic lake factors linked to decreasing duration of lake ice and snow cover rather than to limnological impacts associated with increased glacial runoff.

scholarly journals Big Questions, Few Answers About What Happens Under Lake Ice

Eos ◽  
2020 ◽  
Vol 101 ◽  
Author(s):  
Stephanie Hampton ◽  
Stephen Powers ◽  
Shawn Devlin ◽  
Diane McKnight
Keyword(s):  
Ice Cover ◽  
Lake Ice ◽  
Cold Temperatures

Scientists long eschewed studying lakes in winter, expecting that cold temperatures and ice cover limited activity below the surface. Recent findings to the contrary are changing limnologists’ views.

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