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 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 Gas properties of winter lake ice in Northern Sweden: biogeochemical processes and implication for carbon gas release

2011 ◽  
Vol 8 (5) ◽  
pp. 9639-9669 ◽  
Author(s):  
T. Boereboom ◽  
M. Depoorter ◽  
S. Coppens ◽  
J.-L. Tison
Keyword(s):  
Ghg Emissions ◽  
Open Water ◽  
Ice Cover ◽  
Boreal Lakes ◽  
Gas Content ◽  
Lake Ice ◽  
Mixing Ratios ◽  
Discontinuous Permafrost ◽  
History Of ◽  
Gas Properties

Abstract. This paper describes gas composition, total gas content and bubbles characteristics in winter lake ice for four adjacent lakes in a discontinuous permafrost area. Our gas mixing ratios suggest that gas exchange occurs between the bubbles and the water before entrapment in the ice. Comparison between lakes enabled us to identify 2 major "bubbling events" shown to be related to a regional drop of atmospheric pressure. Further comparison demonstrates that winter lake gas content is strongly dependent on hydrological connections: according to their closed/open status with regards to water exchange, lakes build up more or less greenhouse gases (GHG) in their water and ice cover during the winter, and release it during spring melt. These discrepancies between lakes need to be taken into account when establishing a budget for permafrost regions. Our analysis allows us to present a new classification of bubbles, according to their gas properties. Our methane emission budget (from 6.52 10−5 to 12.7 mg CH4 m−2 d−1) for the three months of winter ice cover is complementary to the other budget estimates, taking into account the variability of the gas distribution in the ice and between the various types of lakes. Most available studies on boreal lakes have focused on quantifying GHG emissions from sediment by means of various systems collecting gases at the lake surface, and this mainly during the summer "open water" period. Only few of these have looked at the gas enclosed in the winter ice-cover itself. Our approach enables us to integrate, for the first time, the history of winter gas emission for this type of lakes.

scholarly journals Decay of a High Arctic lake-ice cover: observations and modelling

1994 ◽  
Vol 40 (135) ◽  
pp. 283-292 ◽  
Author(s):  
Richard Heron ◽  
Ming-Ko Woo
Keyword(s):  
Energy Balance ◽  
Ice Cover ◽  
High Arctic ◽  
Shortwave Radiation ◽  
Balance Model ◽  
Lake Ice ◽  
Ice Melt ◽  
Density Reduction ◽  
Ice Water ◽  
Lake Ice Cover

AbstractThe decay of a lake-ice cover in the Canadian High Arctic was studied for 2 years. Melt at the upper surface accounted for 75% of the decrease in ice thickness, while 25% occurred at the ice–water interface. An energy-balance model, incorporating density reduction due to internal ice melt, was used to simulate the decay of the ice cover. The overall performance of the model was satisfactory despite periods when computed results differed from the observed ice decay. Energy-balance calculations indicated that the absorption of shortwave radiation within the ice provided 52% of the melt energy while 33 and 15% came from the surface-energy balance and heat flux from the water.

Phenology of alpine zooplankton populations and the importance of lake ice-out

2020 ◽  
Author(s):  
Kelly A Loria ◽  
Kyle R Christianson ◽  
Pieter T J Johnson
Keyword(s):  
Open Water ◽  
Ice Cover ◽  
Lake Ice ◽  
Aquatic Life ◽  
Phenological Shifts ◽  
Hesperodiaptomus Shoshone ◽  
Term Data ◽  
Alpine Zooplankton ◽  
Observation Period

Abstract The prolonged ice cover inherent to alpine lakes incurs unique challenges for aquatic life, which are compounded by recent shifts in the timing and duration of ice cover. To understand the responses of alpine zooplankton, we analyzed a decade (2009–2019) of open-water samples of Daphnia pulicaria and Hesperodiaptomus shoshone for growth, reproduction and ultraviolet radiation tolerance. Due to reproductive differences between taxa, we expected clonal cladocerans to exhibit a more rapid response to ice-cover changes relative to copepods dependent on sexual reproduction. For D. pulicaria, biomass and melanization were lowest after ice clearance and increased through summer, whereas fecundity was highest shortly after ice-off. For H. shoshone, biomass and fecundity peaked later but were generally less variable through time. Among years, ice clearance date varied by 49 days; years with earlier ice-out and a longer growing season supported higher D. pulicaria biomass and clutch sizes along with greater H. shoshone fecundity. While these large-bodied, stress tolerant zooplankton taxa were relatively resilient to phenological shifts during the observation period, continued losses of ice cover may create unfavorably warm conditions and facilitate invasion by montane species, emphasizing the value of long-term data in assessing future changes to these sensitive ecosystems.

scholarly journals Decay of a High Arctic lake-ice cover: observations and modelling

1994 ◽  
Vol 40 (135) ◽  
pp. 283-292 ◽  
Author(s):  
Richard Heron ◽  
Ming-Ko Woo
Keyword(s):  
Energy Balance ◽  
Ice Cover ◽  
High Arctic ◽  
Shortwave Radiation ◽  
Balance Model ◽  
Lake Ice ◽  
Ice Melt ◽  
Density Reduction ◽  
Ice Water ◽  
Lake Ice Cover

AbstractThe decay of a lake-ice cover in the Canadian High Arctic was studied for 2 years. Melt at the upper surface accounted for 75% of the decrease in ice thickness, while 25% occurred at the ice–water interface. An energy-balance model, incorporating density reduction due to internal ice melt, was used to simulate the decay of the ice cover. The overall performance of the model was satisfactory despite periods when computed results differed from the observed ice decay. Energy-balance calculations indicated that the absorption of shortwave radiation within the ice provided 52% of the melt energy while 33 and 15% came from the surface-energy balance and heat flux from the water.

scholarly journals Water column gradients beneath the summer ice of a High Arctic freshwater lake as indicators of sensitivity to climate change

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paschale N. Bégin ◽  
Yukiko Tanabe ◽  
Milla Rautio ◽  
Maxime Wauthy ◽  
Isabelle Laurion ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Column ◽  
Microbial Mats ◽  
Green Light ◽  
Ice Cover ◽  
High Arctic ◽  
Freshwater Lake ◽  
Temperature Conductivity ◽  
Oxygen Nitrous Oxide ◽  
Future Loss

AbstractIce cover persists throughout summer over many lakes at extreme polar latitudes but is likely to become increasingly rare with ongoing climate change. Here we addressed the question of how summer ice-cover affects the underlying water column of Ward Hunt Lake, a freshwater lake in the Canadian High Arctic, with attention to its vertical gradients in limnological properties that would be disrupted by ice loss. Profiling in the deepest part of the lake under thick mid-summer ice revealed a high degree of vertical structure, with gradients in temperature, conductivity and dissolved gases. Dissolved oxygen, nitrous oxide, carbon dioxide and methane rose with depth to concentrations well above air-equilibrium, with oxygen values at > 150% saturation in a mid-water column layer of potential convective mixing. Fatty acid signatures of the seston also varied with depth. Benthic microbial mats were the dominant phototrophs, growing under a dim green light regime controlled by the ice cover, water itself and weakly colored dissolved organic matter that was mostly autochthonous in origin. In this and other polar lakes, future loss of mid-summer ice will completely change many water column properties and benthic light conditions, resulting in a markedly different ecosystem regime.

scholarly journals The influence of albedo parameterization for improved lake ice simulation

2020 ◽  
Author(s):  
Alexis L. Robinson ◽  
Sarah S. Ariano ◽  
Laura C. Brown
Keyword(s):  
Field Measurements ◽  
Time Lapse ◽  
Ice Cover ◽  
High Arctic ◽  
Arctic Lakes ◽  
Ice Thickness ◽  
Lake Ice ◽  
Temperate Region ◽  
Climate Conditions ◽  
Arctic Lake

Abstract. Lake ice models can be used to study the latitudinal differences of current and projected changes in ice covered lakes under a changing climate. The Canadian Lake Ice Model (CLIMo) is a one-dimensional freshwater ice cover model that simulates Arctic and sub-Arctic lake ice cover well. Modelling ice cover in temperate regions has presented challenges due to the differences in composition between northern and temperate ice. This study presents a comparison of measured and modelled ice regimes, with a focus on refining CLIMo for temperate regions. The study sites include two temperate region lakes (MacDonald Lake and Clear Lake, Central Ontario) and two High Arctic lakes (Resolute Lake and Small Lake, Nunavut) where climate and ice cover information have been recorded over three seasons. The ice cover simulations were validated with a combination of time lapse imagery, field measurements of snow depth, snow density, ice thickness and albedo data, and historical ice records from the Canadian Ice Database (for Resolute Lake). Simulations of the High Arctic ice cover show good agreement with previous studies for ice-on and ice-off dates (MAE 6 to 8 days). Unadjusted simulations for the temperate region lakes show both an underestimation in ice thickness (~ 4 to 18 cm) and ice-off timing (~ 25 to 30 days). Field measurements were used to adjust the albedo parameterization used in CLIMo, which resulted in improvements to both simulated ice thickness, within 0.1 cm to 10 cm of manual measurements, and ice-off timing, within 1 to 7 days of observations. These findings suggest regionally specific measurements of albedo can improve the accuracy of lake ice simulations. These results further our knowledge regarding of the response of temperate and High Arctic lake ice regimes to climate conditions.

scholarly journals Recent changes in pan-Arctic sea ice, lake ice, and snow-on/off timing

2021 ◽  
Vol 15 (10) ◽  
pp. 4781-4805
Author(s):  
Alicia A. Dauginis ◽  
Laura C. Brown
Keyword(s):  
Sea Ice ◽  
Climatic Change ◽  
Open Water ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Regional Variability ◽  
Lake Ice ◽  
The North ◽  
Snow And Ice

Abstract. Arctic snow and ice cover are vital indicators of climate variability and change, yet while the Arctic shows overall warming and dramatic changes in snow and ice cover, the response of these high-latitude regions to recent climatic change varies regionally. Although previous studies have examined changing snow and ice separately, examining phenology changes across multiple components of the cryosphere together is important for understanding how these components and their response to climate forcing are interconnected. In this work, we examine recent changes in sea ice, lake ice, and snow together at the pan-Arctic scale using the Interactive Multisensor Snow and Ice Mapping System 24 km product from 1997–2019, with a more detailed regional examination from 2004–2019 using the 4 km product. We show overall that for sea ice, trends toward earlier open water (−7.7 d per decade, p<0.05) and later final freeze (10.6 d per decade, p<0.05) are evident. Trends toward earlier first snow-off (−4.9 d per decade, p<0.05), combined with trends toward earlier first snow-on (−2.8 d per decade, p<0.05), lead to almost no change in the length of the snow-free season, despite shifting earlier in the year. Sea ice-off, lake ice-off, and snow-off parameters were significantly correlated, with stronger correlations during the snow-off and ice-off season compared to the snow-on and ice-on season. Regionally, the Bering and Chukchi seas show the most pronounced response to warming, with the strongest trends identified toward earlier ice-off and later ice-on. This is consistent with earlier snow-off and lake ice-off and later snow-on and lake ice-on in west and southwest Alaska. In contrast to this, significant clustering between sea ice, lake ice, and snow-on trends in the eastern portion of the North American Arctic shows an earlier return of snow and ice. The marked regional variability in snow and ice phenology across the pan-Arctic highlights the complex relationships between snow and ice, as well as their response to climatic change, and warrants detailed monitoring to understand how different regions of the Arctic are responding to ongoing changes.

scholarly journals Exceptional summer warming leads to contrasting outcomes for methane cycling in small Arctic lakes of Greenland

2017 ◽  
Vol 14 (3) ◽  
pp. 559-574 ◽  
Author(s):  
Sarah B. Cadieux ◽  
Jeffrey R. White ◽  
Lisa M. Pratt
Keyword(s):  
Water Column ◽  
Thermal Stratification ◽  
Open Water ◽  
Methane Flux ◽  
Ice Cover ◽  
Arctic Lakes ◽  
Stratified Lakes ◽  
Water Conditions ◽  
Methane Concentrations ◽  
Methane Dynamics

Abstract. In thermally stratified lakes, the greatest annual methane emissions typically occur during thermal overturn events. In July of 2012, Greenland experienced significant warming that resulted in substantial melting of the Greenland Ice Sheet and enhanced runoff events. This unusual climate phenomenon provided an opportunity to examine the effects of short-term natural heating on lake thermal structure and methane dynamics and compare these observations with those from the following year, when temperatures were normal. Here, we focus on methane concentrations within the water column of five adjacent small lakes on the ice-free margin of southwestern Greenland under open-water and ice-covered conditions from 2012–2014. Enhanced warming of the epilimnion in the lakes under open-water conditions in 2012 led to strong thermal stability and the development of anoxic hypolimnia in each of the lakes. As a result, during open-water conditions, mean dissolved methane concentrations in the water column were significantly (p < 0.0001) greater in 2012 than in 2013. In all of the lakes, mean methane concentrations under ice-covered conditions were significantly (p < 0.0001) greater than under open-water conditions, suggesting spring overturn is currently the largest annual methane flux to the atmosphere. As the climate continues to warm, shorter ice cover durations are expected, which may reduce the winter inventory of methane and lead to a decrease in total methane flux during ice melt. Under open-water conditions, greater heat income and warming of lake surface waters will lead to increased thermal stratification and hypolimnetic anoxia, which will consequently result in increased water column inventories of methane. This stored methane will be susceptible to emissions during fall overturn, which may result in a shift in greatest annual efflux of methane from spring melt to fall overturn. The results of this study suggest that interannual variation in ground-level air temperatures may be the primary driver of changes in methane dynamics because it controls both the duration of ice cover and the strength of thermal stratification.

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.

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