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 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 Effects of loss of perennial lake ice on mixing and phytoplankton dynamics: insights from High Arctic Canada

2010 ◽  
Vol 51 (56) ◽  
pp. 56-70 ◽  
Author(s):  
Julie Veillette ◽  
Marie-Josée Martineau ◽  
Dermot Antoniades ◽  
Denis Sarrazin ◽  
Warwick F. Vincent
Keyword(s):  
Water Column ◽  
Open Water ◽  
Fold Increase ◽  
Ice Cover ◽  
High Arctic ◽  
Meromictic Lakes ◽  
Lake Ice ◽  
Wind Speeds ◽  
Arctic Climate Change ◽  
Perennial Ice

AbstractPerennially ice-covered lakes are well known from Antarctica and also occur in the extreme High Arctic. Climate change has many implications for these lakes, including the thinning and disappearance of their perennial ice cover. The goal of this study was to consider the effects of transition to seasonal ice cover by way of limnological observations on a series of meromictic lakes along the northern coastline of Ellesmere Island, Nunavut, Canada. Conductivity-temperature profiles during a rare period of ice-free conditions (August 2008) in these lakes suggested effects of wind-induced mixing of their surface freshwater layers and the onset of entrainment of water at the halocline. Sampling of the mixed layer of one of these meromictic lakes in May and August 2008 revealed a pronounced vertical structure in phytoplankton pigments and species composition, with dominance by cyanobacteria, green algae, chrysophytes, cryptophytes and dinoflagellates, and a conspicuous absence of diatoms. The loss of ice cover resulted in an 80-fold increase in water column irradiance and apparent mixing of the upper water column during a period of higher wind speeds. Zeaxanthin, a pigment found in cyanobacteria, was entirely restricted to the <3μm cell fraction at all depths and increased by a factor of 2–17, with the greatest increases in the upper halocline region subject to mixing. Consistent with the pigment data, picocyanobacterial populations increased by a factor of 3, with the highest concentration (1.65 × 108 cells L−1) in the upper halocline. Chlorophyll a concentrations and the relative importance of phytoplankton groups differed among the four lakes during the open-water period, implying lake-specific differences in phytoplankton community structure under ice-free conditions.

scholarly journals The fate of lake ice in the North American Arctic

2011 ◽  
Vol 5 (4) ◽  
pp. 869-892 ◽  
Author(s):  
L. C. Brown ◽  
C. R. Duguay
Keyword(s):  
Snow Cover ◽  
North American ◽  
Climate Model ◽  
Regional Climate ◽  
Ice Cover ◽  
Lake Ice ◽  
The North ◽  
North American Arctic ◽  
Break Up ◽  
Perennial Ice

Abstract. Lakes comprise a large portion of the surface cover in northern North America, forming an important part of the cryosphere. The timing of lake ice phenological events (e.g. break-up/freeze-up) is a useful indicator of climate variability and change, which is of particular relevance in environmentally sensitive areas such as the North American Arctic. Further alterations to the present day ice regime could result in major ecosystem changes, such as species shifts and the disappearance of perennial ice cover. The Canadian Lake Ice Model (CLIMo) was used to simulate lake ice phenology across the North American Arctic from 1961–2100 using two climate scenarios produced by the Canadian Regional Climate Model (CRCM). Results from the 1961–1990 time period were validated using 15 locations across the Canadian Arctic, with both in situ ice cover observations from the Canadian Ice Database as well as additional ice cover simulations using nearby weather station data. Projected changes to the ice cover using the 30-year mean data between 1961–1990 and 2041–2070 suggest a shift in break-up and freeze-up dates for most areas ranging from 10–25 days earlier (break-up) and 0–15 days later (freeze-up). The resulting ice cover durations show mainly a 10–25 day reduction for the shallower lakes (3 and 10 m) and 10–30 day reduction for the deeper lakes (30 m). More extreme reductions of up to 60 days (excluding the loss of perennial ice cover) were shown in the coastal regions compared to the interior continental areas. The mean maximum ice thickness was shown to decrease by 10–60 cm with no snow cover and 5–50 cm with snow cover on the ice. Snow ice was also shown to increase through most of the study area with the exception of the Alaskan coastal areas.

A day in the life of winter plankton: under-ice community dynamics during 24 h in a eutrophic lake

2021 ◽  
Author(s):  
Ariana M Chiapella ◽  
Haley Grigel ◽  
Hannah Lister ◽  
Allison Hrycik ◽  
Brian P O’Malley ◽  
...  
Keyword(s):  
Surface Waters ◽  
Community Dynamics ◽  
Sampling Period ◽  
Eutrophic Lake ◽  
Ice Cover ◽  
Lake Ice ◽  
Ice Dynamics ◽  
Upward Migration ◽  
And Function ◽  
Lipid Stores

Abstract Although diel vertical migration (DVM) in aquatic systems may account for the largest daily migration of biomass globally, our understanding of this process under ice cover is limited, particularly in fresh water. The date of lake ice onset and duration of ice cover is declining globally, therefore determining the extent of plankton migrations under ice is imperative to inform our baseline understanding of seasonal differences in community structure and function, and how conditions may change over time. We investigated whether plankton exhibit DVM under ice and explored interactions between phytoplankton and zooplankton at highly resolved space–time scales across 24 h in a eutrophic system. Despite the dominance of motile taxa, phytoplankton remained vertically segregated based on morpho-functional groups throughout the sampling period. Daphnia mendotae exhibited size-structured DVM with an upward migration at sunset and sunrise, and midnight sinking, presumably to avoid the rise of predatory Chaoborus. We hypothesize that because overwintering daphnids require rich lipid stores, D. mendotae migrated to access small, lipid-rich phytoplankton that were limited to surface waters. Given our study took place during an unusually warm winter in a eutrophic system, our results may represent future under-ice dynamics under increasing eutrophication pressure and climate warming in shallow lakes.

scholarly journals USING REANALYSIS DATA FOR RESEARCHING THE ICE COVER OF THE SEA OF AZOV

2020 ◽  
Vol 2 (5) ◽  
pp. 37-42
Author(s):  
A.A. Magaeva ◽  
◽  
Keyword(s):  
Winter Season ◽  
Ice Cover ◽  
Reanalysis Data ◽  
Sea Of Azov ◽  
Climate Data ◽  
Alternative Source ◽  
Sea Ice Concentration ◽  
The Sea Of Azov ◽  
Air Temperatures

The article presents an analysis of the results of the OSI-450 reanalysis as an alternative data source for the study of the ice cover of the Azov Sea. OSI-450 is the second major version of the OSI SAF Global Sea Ice Concentration Climate Data Record (CDR). The OSI-450 product is available for the period 1979 to 2015.Using licensed software ArcGIS 10.*, a model for data processing was created. The average long-term value of the ice cover for the period 2000–2015 according to the OSI-450 reanalysis data is 23.3 %, according to GIS data – 37.2 %; the maximum and minimum values are 43 % / 69.4 % and 8.2 % / 8 %, respectively. The correlation coefficient with the sum of average monthly air temperatures is minus 0.87 (air temperature for the winter season is a main factor that determines the ice conditions of the Sea of Azov). It is shown that the OSI-450 reanalysis data underestimate the ice extent for the season, but on the whole reproduces the long-term dynamics of the ice cover for the period under consideration. Based on the study, it was concluded that the OSI-450 reanalysis can act as an alternative source of data on the state of the ice cover, but taking into account correction factors.

Atmospheric teleconnection patterns associated with severe and mild ice cover on the Great Lakes, 1963–2011

2012 ◽  
Vol 47 (3-4) ◽  
pp. 421-435 ◽  
Author(s):  
Xuezhi Bai ◽  
Jia Wang
Keyword(s):  
North America ◽  
Great Lakes ◽  
El Niño ◽  
El Nino ◽  
Ice Cover ◽  
Reanalysis Data ◽  
Teleconnection Pattern ◽  
La Niña ◽  
Atmospheric Teleconnection ◽  
La Nina

Atmospheric teleconnection circulation patterns associated with severe and mild ice cover over the Great Lakes are investigated using the composite analysis of lake ice data and National Center of Environmental Prediction (NCEP) reanalysis data for the period 1963–2011. The teleconnection pattern associated with the severe ice cover is the combination of a negative North Atlantic Oscillation (NAO) or Arctic Oscillation (AO) and negative phase of Pacific/North America (PNA) pattern, while the pattern associated with the mild ice cover is the combination of a positive PNA (or an El Niño) and a positive phase of the NAO/AO. These two extreme ice conditions are associated with the North American ridge–trough variations. The intensified ridge–trough system produces a strong northwest-to-southeast tilted ridge and trough and increases the anomalous northwesterly wind, advecting cold, dry Arctic air to the Great Lakes. The weakened ridge–trough system produces a flattened ridge and trough, and promotes a climatological westerly wind, advecting warm, dry air from western North America to the Great Lakes. Although ice cover for all the individual lakes responds roughly linearly and symmetrically to both phases of the NAO/AO, and roughly nonlinearly and asymmetrically to El Niño and La Niña events, the overall ice cover response to individual NAO/AO or Niño3.4 index is not statistically significant. The combined NAO/AO and Niño3.4 indices can be used to reliably project severe ice cover during the simultaneous –NAO/AO and La Niña events, and mild ice cover during the simultaneous +NAO/AO and El Niño events.

scholarly journals Thinner Sea Ice Contribution to the Remarkable Polynya Formation North of Greenland in August 2018

2021 ◽  
Author(s):  
Xiaoyi Shen ◽  
Chang-Qing Ke ◽  
Bin Cheng ◽  
Wentao Xia ◽  
Mengmeng Li ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ice Cover ◽  
Reanalysis Data ◽  
Mean Value ◽  
Ocean Model ◽  
North Coast ◽  
Average Value ◽  
The North ◽  
Wind Sea ◽  
The One

AbstractIn August 2018, a remarkable polynya was observed off the north coast of Greenland, a perennial ice zone where thick sea ice cover persists. In order to investigate the formation process of this polynya, satellite observations, a coupled ice-ocean model, ocean profiling data, and atmosphere reanalysis data were applied. We found that the thinnest sea ice cover in August since 1978 (mean value of 1.1 m, compared to the average value of 2.8 m during 1978–2017) and the modest southerly wind caused by a positive North Atlantic Oscillation (mean value of 0.82, compared to the climatological value of −0.02) were responsible for the formation and maintenance of this polynya. The opening mechanism of this polynya differs from the one formed in February 2018 in the same area caused by persistent anomalously high wind. Sea ice drift patterns have become more responsive to the atmospheric forcing due to thinning of sea ice cover in this region.

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).

Comparison of field data with theories on ice cover progression in large rivers

1984 ◽  
Vol 11 (4) ◽  
pp. 798-814 ◽  
Author(s):  
Bernard Michel
Keyword(s):  
Quantitative Determination ◽  
Key Words ◽  
Field Data ◽  
Ice Cover ◽  
Large Rivers ◽  
Ice Dynamics ◽  
Physical Mechanisms ◽  
Flow Parameters ◽  
Existing Data ◽  
St Lawrence River

There are many theories pertaining to the progression of ice covers in rivers fed by frazil slush and floes but very few have been examined critically by comparing them with field data. In this paper the existing theories on dynamic ice cover progression are reviewed, an additional one is proposed, and they are classified according to the physical mechanisms that are involved. Finally, they are compared with some existing field data for large rivers. The data are extremely scarce and difficult to obtain because of the costs involved and the dangers in traveling over thin ice when the ice cover is being formed.It is usually easier to get only the critical values of parameters giving the limits of ice cover progression. In this paper, complete data were taken from the St. Lawrence River, the Beauharnois Canal, and the La Grande Rivière where the ice thicknesses along with the flow parameters have been measured.In these cases the existing data are adequate, so they could be grouped to explain the various mechanisms involved and to obtain numerical values for their quantitative determination. Key words: glaciology, river ice, ice dynamics, fluvial processes, ice hydraulics.

scholarly journals Correlation and trend studies of the sea-ice cover and surface temperatures in the Arctic

2002 ◽  
Vol 34 ◽  
pp. 420-428 ◽  
Author(s):  
Josefino C. Comiso
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Ice Cover ◽  
The Arctic ◽  
Temperature Anomalies ◽  
Ice Concentration ◽  
Arctic Ice ◽  
Highly Correlated ◽  
Surface Ice ◽  
Perennial Ice

AbstractCo-registered and continuous satellite data of sea-ice concentrations and surface ice temperatures from 1981 to 2000 are analyzed to evaluate relationships between these two critical climate parameters and what they reveal in tandem about the changing Arctic environment. During the 19 year period, the Arctic ice extent and actual ice area are shown to be declining at a rate of –2.0±0.3% dec –1 and 3.1 ±0.4% dec–1, respectively, while the surface ice temperature has been increasing at 0.4 ±0.2 K dec–1, where dec is decade. The extent and area of the perennial ice cover, estimated from summer minimum values, have been declining at a much faster rate of –6.7±2.4% dec–1 and –8.3±2.4% dec–1, respectively, while the surface ice temperature has been increasing at 0.9 ±0.6K dec–1. This unusual rate of decline is accompanied by a very variable summer ice cover in the 1990s compared to the 1980s, suggesting increases in the fraction of the relatively thin second-year, and hence a thinning in the perennial, ice cover during the last two decades. Yearly anomaly maps show that the ice-concentration anomalies are predominantly positive in the 1980s and negative in the 1990s, while surface temperature anomalies were mainly negative in the 1980s and positive in the 1990s. The yearly ice-concentration and surface temperature anomalies are highly correlated, indicating a strong link especially in the seasonal region and around the periphery of the perennial ice cover. The surface temperature anomalies also reveal the spatial scope of each warming (or cooling) phenomenon that usually extends beyond the boundaries of the sea-ice cover.

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