White Ice Research Articles

The radiative and geometric properties of melting first-year landfast sea ice in the Arctic

Abstract. In polar regions, sea ice is a crucial mediator of the interaction between Earth's atmosphere and oceans. Its formation and breakup is intimately connected with large-scale climatic processes, local weather patterns, and the use of sea ice in coastal Arctic regions by Indigenous people. In order to investigate the physical phenomena at the heart of this process, a set of targeted, intensive observations were made over spring sea ice melt and breakup in Kotzebue Sound, Alaska. These observations were planned and executed through a collaborative effort in which an Indigenous Elder advisory council from Kotzebue and scientists participated in co-production of hypotheses and observational research, including a stronger understanding of the physical properties of sea ice during spring melt. Here we present the results of observations performed using high-endurance, fixed-wing uncrewed aerial vehicles (UAVs) containing custom-built scientific payloads. Repeated flights over the measurement period captured the early stages of the transition from a white, snow-covered state to a broken-up, bare blue-green state. We found that the reflectance of sea ice features depends strongly on their size. Snow patches get darker as they get smaller, an effect owed to the geometric relationship between the bright interior and the darker, melting feature edges. Conversely, bare patches get darker as they get larger. For the largest ice features observed, bare blue-green ice patches were found to be ≈ 20 % less reflective than average across all observational cases, while large snowy white ice patches were found to be ≈ 20 % more reflective than that same average.

Dynamic Thresholding Fully Automated sea ice extraction and classification methods based on multi-source remote-sensing data in the Yellow sea and Bohai sea regions

This paper presents the extraction and classification of sea ice in the Yellow and Bohai seas using multi-source remote sensing products, including Landsat 8, HY-1C, and MODIS. We propose a Dynamic Thresholding Fully Automated (DTFA) method for sea ice extraction and classification. The accuracy of sea ice extraction and classification is evaluated using four metrics: confusion matrix accuracy rate, overall accuracy, user accuracy, and kappa coefficient. The DTFA method showed higher extraction and classification accuracy compared to the SVM and k-means++ methods. HY-1C has the most effective extraction, followed by Landsat 8. Landsat 8 is able to extract new ice, grey ice, and grey-white ice with the best effect, while HY-1C has a better effect in extracting white ice. MODIS data has advantages in coverage and data updating. Finally, the fusion of multi-source remote sensing images was used to obtain the sea ice extent of the entire Chinese offshore. This method is also applicable to remote sensing monitoring of sea ice in other sea areas.

Assessment of Sea-Ice Classification Capabilities during Melting Period Using Airborne Multi-Frequency PolSAR Data

Sea-ice mapping using Synthetic Aperture Radar (SAR) in the melt season poses challenges, primarily due to meltwater complicating the distinguishability of sea-ice types. In response to this issue, this study introduces a novel method for classifying sea ice during the Bohai Sea’s melting period. The method categorizes sea ice into five types: open water (OW), gray ice (Gi), melting gray ice (GiW), gray–white Ice (Gw), and melting gray–white Ice (GwW). To achieve this classification, 51 polarimetric features are extracted from L-, S-, and C-band PolSAR data using various polarization decomposition methods. This study assesses the separability of these features among different combinations of sea-ice type by calculating the Euclidean distance (ED). The Support Vector Machine (SVM) classifier, when employed with single-frequency polarimetric feature sets, achieves the highest accuracy for OW and Gi in the C-band, GiW in the S-band, and Gw and GwW in the L-band. Remarkably, the C-band features exhibit the overall highest accuracy when compared to the L-band and S-band. Furthermore, employing a multi-dimensional polarimetric feature set significantly improves classification accuracy to 94.55%, representing a substantial enhancement of 9% to 22% compared to single-frequency classification. Benefiting from the performance advantages of Random Forest (RF) classifiers in handling large datasets, RF classifiers achieve the highest classification accuracy of 95.84%. The optimal multi-dimensional feature composition includes the following: L-band: SE, SEI, α¯, Span; S-band: SEI, SE, Span, PV-Freeman, λ1, λ2; C-band: SE, SEI, Span, λ3, PV-Freeman. The results of this study provide a reliable new method for future sea-ice monitoring during the melting season.

Gas dynamics within landfast sea ice of an Arctic fjord (NE Greenland) during the spring–summer transition

Sea ice is an active component of the Earth’s climate system, interacting with both the atmosphere and the ocean. Arctic sea ice is commonly covered by melt ponds during late spring and summer, strongly affecting sea ice physical and optical properties. How melt pond formation affects sea ice gas dynamics and exchanges between sea ice and the atmosphere, with potential feedbacks on climate, is not well known. Here we measured concentrations of N2, O2, and Ar, total alkalinity, and dissolved inorganic carbon within sea ice of Young Sound, NE Greenland, to examine how melt pond formation and meltwater drainage through the ice affect its physical properties and gas composition, including impacts on CO2 exchange with the atmosphere. Sea ice gas composition was controlled mainly by physical processes, with most of the gas initially in gaseous form in the upper ice layer. A minor contribution from biological processes was associated with positive estimates of net community production (up to 2.6 µmol Lice−1 d−1), indicating that the ice was net autotrophic. As the sea ice warmed, the upper ice gas concentrations decreased, suggesting a release of gas bubbles to the atmosphere. However, as melt ponds formed, the ice surface became strongly depleted in gases. Due to melt pond development, meltwater permeated through the ice, resulting in the formation of an underwater ice layer also depleted in gases. Sea ice, including brine, slush, and melt ponds, was undersaturated in CO2 compared to the atmosphere, supporting an uptake of up to −4.26 mmol m−2 d−1 of atmospheric CO2. As melt pond formation progressed, however, this uptake weakened in the strongly altered remaining ice surface (the “white ice”), averaging −0.04 mmol m−2 d−1. This study reveals the importance of melt pond formation and dynamics for sea ice gas composition.

Under‐ice plankton community response to snow removal experiment in bog lake

AbstractAlthough previously overlooked, winter is now seen as a period of significant biological activity in the annual cycle of north‐temperate lakes. Research suggests a future of reduced ice cover duration and altered snow conditions could significantly change the functioning of aquatic ecosystems. This study seeks to explore the possible repercussions of changing ice and snow dynamics on aquatic biological communities, particularly at lower trophic levels. To explore plankton community responses to changing under‐ice light conditions, we performed a whole‐lake manipulation by removing all of the snow from the surface of a north temperate bog lake in northern Wisconsin. Over three winters, samples were collected under ice in the study lake, South Sparkling Bog. The first winter, 2018–2019, served as a reference year during which snow was not removed from the lake and was followed by two subsequent winters of snow removal during 2019–2020 and 2020–2021. Data collected included phytoplankton and zooplankton abundances and taxa, chlorophyll a, dissolved organic carbon, light, Secchi depth, and ice and snow thickness. In our snow removal years, increased light availability in the water column shifted the phytoplankton community from low‐biomass, mixed community of potential mixotrophs, unicellular cyanobacteria and Chlorophytes to dominance by photoautotrophs, and rotifer zooplankton densities increased. Ice condition, specifically the thickness of white ice vs. black ice, was a major driver in the magnitude of change between years. This research improves our understanding of how plankton communities might respond to climate‐change driven shifts in winter dynamics for north temperate systems.

Spatial variability of characteristics of the ice cover of the Rybinsky reservoir in winter 2022

The paper presents the results and a brief analysis of in-situ measurements of thickness and other characteristics of the ice cover of the Rybinsky reservoir, which took place during two expeditions in February and April 2022. In expeditions, 49 ice cores were taken, which provide enough information to evaluate the heterogeneity of the ice cover. The most accurate data were obtained for two profiles, which cross the reservoir from the north to the south and from the southwest to the northeast and coincide with two tracks of the satellite altimeter Jason-3. In 2022 ice cover of the Rybinsky reservoir was heterogeneous and made up several different ice layers. Combination and thickness of these layers were distributed unevenly over the surface of the reservoir and were changing over time. The most uneven distribution was observed in the winter: near the shore and in the southwest part of the reservoir ice cover consisted of black ice, central part of the reservoir was made of black ice and frazil ice and east part of the reservoir was made up black ice and white ice. In the spring, ice cover became much more homogeneous and consisted of thick layers of white ice and black ice.

Towards critical white ice conditions in lakes under global warming

The quality of lake ice is of uppermost importance for ice safety and under-ice ecology, but its temporal and spatial variability is largely unknown. Here we conducted a coordinated lake ice quality sampling campaign across the Northern Hemisphere during one of the warmest winters since 1880 and show that lake ice during 2020/2021 commonly consisted of unstable white ice, at times contributing up to 100% to the total ice thickness. We observed that white ice increased over the winter season, becoming thickest and constituting the largest proportion of the ice layer towards the end of the ice cover season when fatal winter drownings occur most often and light limits the growth and reproduction of primary producers. We attribute the dominance of white ice before ice-off to air temperatures varying around the freezing point, a condition which occurs more frequently during warmer winters. Thus, under continued global warming, the prevalence of white ice is likely to substantially increase during the critical period before ice-off, for which we adjusted commonly used equations for human ice safety and light transmittance through ice.

Features of Late Pleistocene massive ice formation in the central Yamal Peninsula based on isotopic signature (18O, 2H) of ice

On Yamal Peninsula massive ice is widespread cryogenic object, lying close to the surface in different sediments, often in a combination with ice wedges. This study is dedicated to tabular massive ground ice exposed in the outcrop of the thermocirque of the third sea terrace in the Central Yamal Peninsula to establish the mechanism of ice formation and the source of water based on the isotopic signature of ice. The tabular massive ground ice body was opened with visual thickness of 2.5 m and a length of 300 m. It had formed from 43 to 37 cal ka BP according to 14C AMS-data. A white ice body was found under the visible lower boundary of the studied tabular massive ground ice. Tabular massive ground ice yielded values of δ18О from −19.9 to −23.1‰ and δ2H from −151.8 to −164.7‰, with variations in deuterium excess from 6.5 to 20.4‰ (average dexc = 13‰). The δ18О and δ2H values of white ice vary from −17.5 to −22.5‰, and from −132.6 to −165.3‰ respectively. The δ2H-δ18О relationship for white ice indicating the injection of water and its freezing in a closed system condition. The study shows that the tabular massive ground ice is an intra-ground ice formed under sub-aquatic conditions from lake water. During syngenetic accumulation of segregated massive ice unstable freezing took place, widespread feature of cold regions, which led to intrusion of water under pressure and form injection ice.

SNICAR-ADv4: a physically based radiative transfer model to represent the spectral albedo of glacier ice

Abstract. Accurate modeling of cryospheric surface albedo is essential for our understanding of climate change as snow and ice surfaces regulate the global radiative budget and sea-level through their albedo and mass balance. Although significant progress has been made using physical principles to represent the dynamic albedo of snow, models of glacier ice albedo tend to be heavily parameterized and not explicitly connected with physical properties that govern albedo, such as the number and size of air bubbles, specific surface area (SSA), presence of abiotic and biotic light absorbing constituents (LACs), and characteristics of any overlying snow. Here, we introduce SNICAR-ADv4, an extension of the multi-layer two-stream delta-Eddington radiative transfer model with the adding–doubling solver that has been previously applied to represent snow and sea-ice spectral albedo. SNICAR-ADv4 treats spectrally resolved Fresnel reflectance and transmittance between overlying snow and higher-density glacier ice, scattering by air bubbles of varying sizes, and numerous types of LACs. SNICAR-ADv4 simulates a wide range of clean snow and ice broadband albedo (BBA), ranging from 0.88 for (30 µm) fine-grain snow to 0.03 for bare and bubble-free ice under direct light. Our results indicate that representing ice with a density of 650 kg m−3 as snow with no refractive Fresnel layer, as done previously, generally overestimates the BBA by an average of 0.058. However, because most naturally occurring ice surfaces are roughened “white ice”, we recommend modeling a thin snow layer over bare ice simulations. We find optimal agreement with measurements by representing cryospheric media with densities less than 650 kg m−3 as snow and larger-density media as bubbly ice with a Fresnel layer. SNICAR-ADv4 also simulates the non-linear albedo impacts from LACs with changing ice SSA, with peak impact per unit mass of LACs near SSAs of 0.1–0.01 m2 kg−1. For bare, bubble-free ice, LACs actually increase the albedo. SNICAR-ADv4 represents smooth transitions between snow, firn, and ice surfaces and accurately reproduces measured spectral albedos of a variety of glacier surfaces. This work paves the way for adapting SNICAR-ADv4 to be used in land ice model components of Earth system models.

Estimating Surface Albedo of Arctic Sea Ice Using an Ensemble Back-Propagation Neural Network: Toward a Better Consideration of Reflectance Anisotropy and Melt Ponds

The surface albedo of Arctic sea ice is a critical variable in the Earth’s energy budget, and various Arctic sea ice albedo datasets have been derived from remote sensing data. However, the influences of reflectance anisotropy and melt ponds were not well considered in previous studies. To improve the estimation accuracy and calculation efficiency, we developed a method for estimating the surface albedo of Arctic sea ice using an ensemble back-propagation neural network (EBPNN) model. A bidirectional reflectance distribution function (BRDF)/albedo dataset of snow, white ice, and melt ponds was constructed using the asymptotic analytical radiative transfer (AART) model, and the nonlinear relationships between the surface reflectance of Moderate Resolution Imaging Spectroradiometer (MODIS) and surface albedo were established using the EBPNN model (prediction correlation coefficient (R) = 0.996, and root mean square error (RMSE) = 0.023). Our results are consistent with the in situ measurements and the Medium Resolution Imaging Spectrometer (MERIS) product (R = 0.916, RMSE = 0.085, and bias = 0.001), in which the reflectance anisotropy of the snow/ice and the influence of melt ponds were fully considered, and the calculation efficiency was significantly improved by using the EBPNN model. The results of this study provide new insights for estimating the Arctic sea ice albedo from satellite observations, and the proposed EBPNN method can be used to generate a long-term Arctic sea ice albedo dataset with a superior estimation accuracy and calculation efficiency.

A novel method for detecting lake ice cover using optical satellite data

Seasonal lake ice is sensitive to temperature fluctuations and long-term temperature trends. It is therefore a good indicator of climate warming, which will likely have dramatic impacts on lake ice phenology in northern latitudes. Beside the climate change aspect, lake ice data are important regarding transport and safety issues. In addition, changes in ice cover affect the ecology of the lake and water quality.A new method for accessing lake ice extent (LIE) using optical satellite data was developed at the Finnish Environment Institute. The resulting ICEmod method is based on multidimensional Gaussian distributions calculated for training data using several reflectance and thermal bands and their-related indices. Three alternative classes are provided for a lake ice pixel: (i) open water, (ii) ice cover, and (iii) cloud. The main advantages of ICEmod are the utilization of several spectral bands, inclusion of simultaneous cloud detection, definition of statistical probability for each pixel, the simplicity of processing and easy transition between different satellite sensors. This novel method is applied in the provision of the Sentinel-3 Sea and Land Surface Temperature Radiometer (SLSTR) -based 0.005° Lake Ice Extent product (LIE-NH) for the Northern Hemisphere under the Global Land Service, a component of the Copernicus Land Service.The 0.005° resolution LIE products based on ICEmod applied to SLSTR (an extensive subset corresponding to LIE-NH) were validated against high-resolution Sentinel-2 Multispectral Instrument -images covering lakes in the different parts of the Northern Hemisphere, most of them representing both open water and ice pixels. The gained overall classification accuracy is 96%. The resulting omission error for ice is 6% and omission mainly occurs in lakes where the ice is very dark and fragmented. The ICEmod method is not always able to separate dark ice from open water if there is water on the top of the dark ice, while misclassifications do not occur if the water layer is on white ice. The commission error for ice is 2.5% and is mostly related to the ambiguity in the definition of a ice-pixel: i.e. whether a 0.005° LIE pixel should be classified as ice or open water when the area within the pixel is partially ice-covered. When the lake is completely ice-covered or ice-free, the overall accuracy is 100%. According to the tentative qualitative comparison with European Space Agency Climate Change Initiative Lake Ice Cover (LIC) product, LIE-NH may provide more accurate lake ice information, and it also provides lake ice data for more than 13 000 lakes while LIC operates for 250 lakes only.

Parameterization of Solar Radiation Absorption by Snow–ice Cover in the Thermodynamic Sea Ice Model of the Sea of Azov

Purpose. The work is aimed at assessing the influence of choice of the parameterization scheme of the snow and ice radiation features upon reproduction of seasonal evolution of the snow–ice cover thickness and temperature distribution in it in the Taganrog Bay top part. Methods and Results. Thermal seasonal dynamics of the snow–ice cover thickness in the northeastern part of the Taganrog Bay was studied using a non-stationary thermodynamic model of sea ice. The model reproduces formation of ice and accumulation of snow on its surface, spatial-temporal change in their thermophysical characteristics, melting of the snow–ice cover, vertical distribution of temperature, and solar radiation absorbed in its thickness at a preset timed data on the meteorological parameters. In the numerical solution of the heat conductivity equation for snow and ice including a radiation source, a computational grid permitting to maintain spatial resolution of the temperature profiles in the snow–ice cover during its melting and growth was applied. Two variants of parameterization of solar radiation transfer in the sea ice were considered. The first version assumed exponential decay of radiation with the constant transmittance and extinction coefficients. In the second one, a two-layer scheme of the solar radiation penetration into ice was used; it simulated the near-surface transition layer. Attenuation of intensity of solar radiation in the snow thickness was described by the Bouguer–Lambert law with the extinction coefficient both as independent of the snow thermophysical characteristics and as represented by the function of its density. The numerical experiments with the purpose to reproduce seasonal evolution of the snow–ice cover thickness and its vertical temperature profile in the Taganrog Bay top part were performed for the winter season, 2016/17. Comparative analysis of the simulation results and the sea ice thickness values taken from the ESIMO ice maps made it possible to choose a combination of the model parameters that provides the best correspondence between the calculated and actual values. Conclusions. It is shown that in reproducing the seasonal changes in the ice cover thickness in the Taganrog Bay top part in winter, 2016/17, the choice of the transmittance and extinction coefficients for white ice represented by the cloudiness functions, on the one hand, and the thickness of the layer with the most intense absorption of short-wave radiation ~ 4 cm, on the other, turned out to be the most justified.

Parametrizatsiya pogloshcheniya solnechnoy radiatsii snezhno-ledyanym pokrovom v termodinamicheskoy modeli l'da Azovskogo morya

Purpose. The work is aimed at assessing the influence of choice of the parameterization scheme of the snow and ice radiation features upon reproduction of seasonal evolution of the snow-ice cover thickness and temperature distribution in it in the Taganrog Bay top part. Methods and Results. Thermal seasonal dynamics of the snow-ice cover thickness in the northeastern part of the Taganrog Bay was studied using a non-stationary thermodynamic model of sea ice. The model reproduces formation of ice and accumulation of snow on its surface, spatial-temporal change in their thermophysical characteristics, melting of the snow-ice cover, vertical distribution of temperature, and solar radiation absorbed in its thickness at a preset timed data on the meteorological parameters. In the numerical solution of the heat conductivity equation for snow and ice including a radiation source, a computational grid permitting to maintain spatial resolution of the temperature profiles in the snowice cover during its melting and growth was applied. Two variants of parameterization of solar radiation transfer in the sea ice were considered. The first version assumed exponential decay of radiation with the constant transmittance and attenuation coefficients. In the second one, a two-layer scheme of the solar radiation penetration into ice was used; it simulated the near-surface transition layer. Attenuation of intensity of solar radiation in the snow thickness was described by the Bouguer – Lambert law with the attenuation coefficient both as independent of the snow thermophysical characteristics and as represented by the function of its density. The numerical experiments with the purpose to reproduce seasonal evolution of the snow-ice cover thickness and its vertical temperature profile in the Taganrog Bay top part were performed for the winter season, 2016/17. Comparative analysis of the simulation results and the sea ice thickness values taken from the ESIMO ice maps made it possible to choose a combination of the model parameters that provides the best correspondence between the calculated and actual values. Conclusions. It is shown that in reproducing the seasonal changes in the ice cover thickness in the Taganrog Bay top part in winter, 2016/17, the choice of the transmittance and attenuation coefficients for white ice represented by the cloudiness functions, on the one hand, and the thickness of the layer with the most intense absorption of short-wave radiation ∼ 4 cm, on the other, turned out to be the most justified.

Skating on Thin White Ice: Imagining a Queer Futurity in Hockey

(Queer) women’s hockey and (men’s) hockey culture often exist in a recursive relationship whereby (queer) women’s hockey is complicit with the problematic associations of hockey and its culture in the present, while also producing an alternate vision of hockey that is feminist, communal, loving, and egalitarian, and extends into a future that is becoming. In this article, the term hockeynormativity communicates how hockey normalizes a white, heterosexual nationalism, and I also posit that Judith Alguire’s overlooked 1995 women’s hockey novel, Iced, is a work of queer futurity that envisions queer women’s hockey as a potentiality that reaches beyond the here and now (of hockey and nationhood) and towards utopia. This article ultimately proposes that thinking through queer (women’s) hockey as a utopian process, rather than simply a variation of men’s hockey, could allow for queerness rather than hockey culture to construct new possibilities for the (women’s) game in the here and now that extend into potential futures.

Spectral attenuation coefficients from measurements of light transmission in bare ice on the Greenland Ice Sheet

Abstract. Light transmission into bare glacial ice affects surface energy balance, biophotochemistry, and light detection and ranging (lidar) laser elevation measurements but has not previously been reported for the Greenland Ice Sheet. We present measurements of spectral transmittance at 350–900 nm in bare glacial ice collected at a field site in the western Greenland ablation zone (67.15∘ N, 50.02∘ W). Empirical irradiance attenuation coefficients at 350–750 nm are ∼ 0.9–8.0 m−1 for ice at 12–124 cm depth. The absorption minimum is at ∼ 390–397 nm, in agreement with snow transmission measurements in Antarctica and optical mapping of deep ice at the South Pole. From 350–530 nm, our empirical attenuation coefficients are nearly 1 order of magnitude larger than theoretical values for optically pure ice. The estimated absorption coefficient at 400 nm suggests the ice volume contained a light-absorbing particle concentration equivalent to ∼ 1–2 parts per billion (ppb) of black carbon, which is similar to pre-industrial values found in remote polar snow. The equivalent mineral dust concentration is ∼ 300–600 ppb, which is similar to values for Northern Hemisphere warm periods with low aeolian activity inferred from ice cores. For a layer of quasi-granular white ice (weathering crust) extending from the surface to ∼ 10 cm depth, attenuation coefficients are 1.5 to 4 times larger than for deeper bubbly ice. Owing to higher attenuation in this layer of near-surface granular ice, optical penetration depth at 532 nm is 14 cm (20 %) lower than asymptotic attenuation lengths for optically pure bubbly ice. In addition to the traditional concept of light scattering on air bubbles, our results imply that the granular near-surface ice microstructure of weathering crust is an important control on radiative transfer in bare ice on the Greenland Ice Sheet ablation zone, and we provide new values of flux attenuation, absorption, and scattering coefficients to support model development and validation.

Brown skin, white ice: South Asian specific ice hockey programming in Canada

ABSTRACT Ice hockey is traditionally known as a ‘white man’s sport’; however, this is a fabricated history that has erased Black and Indigenous contributions to the game. With changing demographics in settler nations such as Canada, racialized citizens are starting to challenge who is allowed to participate and speak about traditionally white-dominated cultural practices. This study uses interview data, media analysis, and reflective vignettes to examine the work that Apna Hockey does to unsettle the whiteness of ice hockey culture in Canada by amplifying the voices and experiences of South Asian hockey participants. Apna Hockey challenges dominant stereotypes about South Asian athletes and bodies through its networking opportunities and social media platforms. We argue that, even though Apna Hockey cannot undo racism in hockey by itself, it does important work with respect to creating and taking space that has never previously been afforded to racialized participants.

Spatial Heterogeneity as a Key Variable Influencing Spring-Summer Progression in UVR and PAR Transmission Through Arctic Sea Ice

The transmission of ultraviolet (UVR) and photosynthetically available radiation (PAR) through sea ice is a key factor controlling under-ice phytoplankton growth in seasonally ice-covered waters. The increase towards sufficient light levels for positive net photosynthesis occurs concurrently with the sea ice melt progression in late spring when ice surface conditions shift from a relatively homogeneous high-albedo snow cover to a less reflective mosaic of bare ice and melt ponds. Here, we present a detailed dataset on the spatial and temporal progression of transmitted UVR and PAR in relation to changing quantities of snow, sea ice and melt ponds. Data were collected with a remotely operated vehicle (ROV) during the GreenEdge landfast sea ice campaign in June-July 2016 in southwestern Baffin Bay. Over the course of melt progression, there was a 10-fold increase in spatially averaged UVR and PAR transmission through the sea ice cover, reaching a maximum transmission of 31% for PAR, 7% for UVB and 26% for UVA radiation. The depth under the sea ice experiencing spatial variability in light levels due to the influence of surface heterogeneity in snow, white ice and melt pond distributions increased from 7 +/- 4 to 20 +/- 6 m over our study. Phytoplankton drifting in under-ice surface waters were thus exposed to variations in PAR availability of up to 43%, highlighting the importance to account for spatial heterogeneity in light transmission through melting sea ice. Consequently, we demonstrate that spatial averages of PAR transmission provided more representative light availability estimates to explain under-ice bloom progression relative to single point irradiance measurements during the sea ice melt season. Encouragingly, the strong dichotomy between white ice and melt pond PAR transmittance and surface albedo permitted a very good estimate of spatially averaged light transmission from drone imagery of the surface and point transmittance measurements beneath different ice surface types.

A MORE DEVASTATING VERSION OF THE RAVEN PARADOX

Hempel's famous Raven Paradox derives from Nicod's criteria for confirmation and the Equivalence Condition, the unintuitive conclusion that things like white roses, green T-shirts and ice cubes confirm the raven hypothesis ‘All ravens are black.’ By a small rearrangement of the Equivalence Condition, I show that we can also derive the conclusion, which sounds even more intuitively intolerable, that observation of black ravens fails to confirm the raven hypothesis. We are left with the contradictory result that black ravens both confirm and do not confirm the raven hypothesis.

Ice processes on medium‐sized north‐temperate lakes

AbstractLake ice supports a range of socio‐economic and cultural activities including transportation and winter recreational actives. The influence of weather patterns on ice‐cover dynamics of temperate lakes requires further understanding for determining how changes in ice composition will impact ice safety and the range of ecosystem services provided by seasonal ice cover. An investigation of lake ice formation and decay for three lakes in Central Ontario, Canada, took place over the course of two winters, 2015–2016 and 2016–2017, through the use of outdoor digital cameras, a Shallow Water Ice Profiler (upward‐looking sonar), and weekly field measurements. Temperature fluctuations across 0°C promoted substantial early season white ice growth, with lesser amounts of black ice forming later in the season. Ice thickening processes observed were mainly through meltwater, or midwinter rain, refreezing on the ice surface. Snow redistribution was limited, with frequent melt events limiting the duration of fresh snow on the ice, leading to a fairly uniform distribution of white ice across the lakes in 2015–2016 (standard deviations week to week ranging from 3 to 5 cm), but with slightly more variability in 2016–2017 when more snow accumulated over the season (5 to 11 cm). White ice dominated the end‐of‐season ice composition for both seasons representing more than 70% of the total ice thickness, which is a stark contrast to Arctic lake ice that is composed mainly of black ice. This research has provided the first detailed lake ice processes and conditions from medium‐sized north‐temperate lakes and provided important information on temperate region lake ice characteristics that will enhance the understanding of the response of temperate lake ice to climate and provide insight on potential changes to more northern ice regimes under continued climate warming.

Skating on White ice: the US media’s representation of Asian/American and Asian female skaters from the mid-2000s to the early 2010s

This article examines how some in the American media covered the emergence of Asian and Asian American athletes in the historically White-dominated sport of figure skating. Utilizing McDonald and Birrell’s Reading Sport Critically approach, we analyzed a variety of major national newspapers, news magazines, sports magazines and periodicals to determine what narratives and beliefs were conveyed to explain the successes of Asian and Asian/American skaters, and the subsequent decline of American skaters. Our results show that some American media members struggled in describing this phenomenon, in that they utilized an essentialist racial lens and viewed the sport as a White space that was experiencing an ‘Asian Invasion’. The findings of this paper add to the race and gender discrimination in sport literature by describing the process that a historically dominant power group (Whites) employed as Asian and Asian American figure skaters started to dominate their White space.