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Timely information on lake ice cover conditions is critical in support of commercial shipping, winter-road transportation, and winter leisure activities such as snowmobiling and ice fishing. Monito...

Spectral albedo and light transmittance through snow, ice, and water were measured in Lake Wuliangsuhai (40 degrees 36 '-41 degrees 30 ' N, 108 degrees 43 '-108 degrees 70 ' E), Inner Mongolia, China, during winter 2016. Data on the weather, structure of lake ice, and geochemistry of water were also collected during the 60-day field program. The study lake is shallow (mean depth 1.0-1.5 m) with a large wetland area. Compared with polar lakes, solar elevation is higher, snow accumulation is much lower, and the ice has more sediment. The ice was all congelation ice with a mean thickness of 36.6 cm, corresponding to a mean air temperature of -9.6 degrees C. The mean daily broadband albedo and photosynthetically active radiation (PAR) band transmittance were 0.54 and 0.08 (bare ice), 0.74 and 0.04 (new snow), and 0.30 and 0.12 (melting period), respectively. The level of light allowed photosynthesis to occur to the bottom of the lake. The ice acted as a grey filter for the sunlight with a mean attenuation coefficient of 2.1 m(-1). These results expand our knowledge of the evolution of light transfer through ice and snow cover and its role in the ecology of lakes in temperate and arid areas.

Changes in climate, warming temperatures and increased precipitation are impacting surface water resources in the Northwest Territories, Canada. Satellite remote sensing is an important tool to mon...

The Tibetan Plateau houses numerous lakes, the phenology and duration of lake ice in this region are sensitive to regional and global climate change, and as such are used as key indicators in climate change research, particularly in environment change comparison studies for the Earth three poles. However, due to its harsh natural environment and sparse population, there is a lack of conventional in situ measurement on lake ice phenology. The Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Snow Index (NDSI) data, which can be traced back 20 years with a 500 m spatial resolution, were used to monitor lake ice for filling the observation gaps. Daily lake ice extent and coverage under clear-sky conditions was examined by employing the conventional SNOWMAP algorithm, and those under cloud cover conditions were re-determined using the temporal and spatial continuity of lake surface conditions through a series of steps. Through time series analysis of every single lake with size greater than 3 km2 in size, 308 lakes within the Tibetan Plateau were identified as the effective records of lake ice extent and coverage to form the Daily Lake Ice Extent and Coverage dataset, including 216 lakes that can be further retrieved with four determinable lake ice parameters: Freeze-up Start (FUS), Freeze-up End (FUE), Break-up Start (BUS), and Break-up End (BUE), and 92 lakes with two parameters, FUS and BUE. Six lakes of different sizes and locations were selected for verification against the published datasets by passive microwave remote sensing. The lake ice phenology information obtained in this paper was highly consistent with that from passive microwave data at an average correlation coefficient of 0.91 and an RMSE value varying from 0.07 to 0.13. The present dataset is more effective at detecting lake ice parameters for smaller lakes than the coarse resolution passive microwave remote sensing observations. The published data are available in https://data.4tu.nl/repository/uuid:fdfd8c76-6b7c-4bbf-aec8-98ab199d9093 and http://www.sciencedb.cn/dataSet/handle/744.

Optical remote sensing images with high temporal resolution can be used to monitor lake ice phenology, a periodic freezing and thawing cycle of ice resulting from seasonal and inter-annual climate ...

In this study, we assess the effect of the lake size on the accuracy of a threshold-based classification of ground-fast and floating lake ice from Sentinel-1 Synthetic Aperture Radar (SAR) imagery. For that purpose, two new methods (flood-fill and watershed method) are introduced and the results between the three classification approaches are compared regarding different lake size classes for a study area covering most of the Yamal Peninsula in Western Siberia. The focus is on April, the stage of maximum lake ice thickness, for the years 2016 and 2017. The results indicate that the largest lakes are likely most prone to errors by the threshold classification. The newly introduced methods seem to improve classification results. The results also show differences in fractions of ground-fast lake ice between 2016 and 2017, which might reflect differences in temperatures between the winters with severe impact on wildlife and freshwater fish resources in the region. Patterns of low backscatter responsible for the classification errors in the centre of the lakes were investigated and compared to the optical Sentinel-2 imagery of late-winter. Strong similarities between some patterns in the optical and SAR data were identified. They might be zones of thin ice, but further research is required for clarification of this phenomenon and its causes.

Evidence is growing that the surface water temperature increases and the duration of ice cover has decreased in many lakes worldwide during the past few decades. Here, we present changes in surface water temperature and ice-cover duration of Lake Lunz from 1921 to 2015 and evaluate how fast these changes occur over time, in particular with respect to other lakes with similar long-term data series. Since 1921, the surface water temperature of this Austrian subalpine lake has increased by 0.8 °C, with the most intense increase recorded during the spring and summer months (~1–2 °C) and less during fall (~0.3 °C). The duration of full lake ice cover has decreased significantly since 1921. During the 1921–2015 study period, Lake Lunz was ice covered for 92 of 94 winters, with ice-free winters in 2006 and 2013. The interannual decrease of the lake ice cover corresponds to 0.36 days less ice cover per year from 1921 to 2015. Freeze dates now occur 17.4 d/100 yr later, and the ice breakup date change is s...

Canada's RADARSAT Constellation Mission (RCM) will have the capacity to acquire C-band compact polarimetry (CP) data in all imaging modes over swaths up to 500 km wide. Our study aimed to assess and develop the utility of RCM CP data for the purpose of lake ice breakup monitoring. The breaking ice and open water information content of RADARSAT-2 (R2) polarimetric data and simulated RCM CP data was compared. Despite relative losses in terms of polarization diversity and radiometric sensitivity, RCM-type CP data were concluded to make a good source of information in support lake ice breakup monitoring. For that reason, a CP-based approach, called CP_LakeIceBC, to classify breaking ice and open water for the purpose of lake ice breakup monitoring was developed. CP_LakeIceBC is driven by incidence angle information, uses five CP backscatter variables (RH, RR, RV/RH, RR/RL, and conformity), and is compatible with high- and medium-resolution RCM-type CP products. Application of CP_LakeIceBC to represe...

Polarimetric and nonpolarimetric C-band SAR parameters were assessed for their potential to discriminate open water versus lake ice. Analysis was done for incidence angles between 18° and 50°. Open water was sampled and modelled at wind speeds of 2–24 m/s, from various directions. Lake ice samples were for new ice, less than two months old. Low-quality data, caused by low-wind slicks and ice slicks, were identified using polarimetric data. Nonparametric testing was used to initially identify parameters with discrimination potential. These parameters were then evaluated throughout the incidence angle range; bounds and thresholds were statistically estimated to provide robust discrimination potential. Classified images were both qualitatively and quantitatively assessed. For single-polarized data, the VV polarization is recommended over HH. Cross-polarized data were limited by sensor noise floors, and are not recommended. Dual co-polarized data, using the co-polarized ratio, were useful discriminators at in...

In this article, we describe a technique to determine dry snow grain size from optical observations. The method is based on analysis of the snow reflectance in the near-infrared region, in particular, the Medium Resolution Imaging Spectrometer MERIS band at 865 nm, which is common to many spaceborne optical sensors, is used. In addition, the algorithm is applied to the Moderate Resolution Imaging Spectroradiometer MODIS 1240 nm band. It is found that bands located at 1020 and 1240 nm are the most suitable for snow grain size remote-sensing applications. The developed method is validated using MODIS observations over flat snow deposited on a lake ice in Hokkaido, Japan.

Multipolarized RADARSAT-2 SAR imagery is used to monitor lake ice during the spring melt period. The study area is Old Crow Flats, Yukon, in the Canadian Arctic. HH and HV backscatter from lake ice is shown to have significant temporal variability and interlake diversity. Backscatter thresholds are statistically estimated to discriminate decaying lake ice from open water. A classification methodology is described that uses a HH backscatter threshold to identify initial break-up and a HV backscatter threshold for the main period of break-up. Classification accuracies are >81% ( = 0.189) prior to initial break-up and 66%–97% ( = 0.353–0.868) during break-up. This study demonstrates the potential of RADARSAT-2 imagery and, by extension, other C-band SAR satellites, to provide lake ice break-up information in support of monitoring and reporting requirements, subsequent decision-making, and scientific tasks for the Government of Canada.

Lake ice records are important in studies of climate (AsSEL& ROBERTSON1995) and aquatic ecosystems (MAGNUSONet aI. 1997). Further analysis of historicallake ice records is needed to improve knowledge of global cryospheric trends (FITZHARRIS1996). An International Workshop on Lake Ice and Climate was held at the University of Wisconsin in 1996 (MAGNUSONet al. 2000) with the general goal of establishing a lake ice database and using it to analyze and interpret long-term ice data for their climatic and ecological content. The analysis described here is made under the auspices of an international "Lake Ice Analysis Group" (LIAG) established at that workshop. In this paper we present a preliminary analysis of 1) variations of long-term average ice-on, ice-off, and ice duration with latitude, and 2) an index of the coherence of ice event dates among five sites over the Northern Hemisphere with relatively continuous records from 1850 to 1995. Our objective is to provide information useful for the assessment and analysis of climate variability, climate change, and aquatic systems.

(2000). Large-scale climatic forcing detected in historical observations of lake ice break-up. SIL Proceedings, 1922-2010: Vol. 27, No. 5, pp. 2775-2783.

Measurements and observations of lake ice movements and lacustrine shore modifications were made in 1986 and 1987 on Lake Kussharo in eastern Hokkaido, Japan. The survey results of lake ice movemen...

Worsley, P. 1975. Some observations on lake ice-push features, Grasvatn, northern Scandinavia. Norsk geogr. Tidsskr. 29, 11–19. A range of ice-push phenomena, including boulder concentrations along the strandline, trails, ramparts, and planed moraine-ridge crests, is described. These phenomena were exposed following the artificial lowering of the level of a sub-Arctic lake. The dominant mechanism for their formation is considered to be the grounding of wind-powered ice floes. The available evidence suggests that the shore profiles were generally adapted to the activity of lake ice, with the result that the current rate of material transport and erosion by ice is low. In the past it seems to have been much more effective.

The morphology, physics, and chemistry of Lake Miers (78° 07′ S, 163° 54′ E), a warm freshwater Antarctic lake, are discussed. The presence of rock debris on the floating lake ice has led to the formation of dirt cones and melt pools. Fossil levels of these pools show that the annual ablation is 15–20 cm. Despite a mean annual air temperature of − 20 ° c, the bottom waters of the lake are at + 5 ° C. This is shown to be a natural example of solar heat storage and the observed temperature profile is satisfactorily accounted for. Chemical evidence suggests that the lake has been filled by freshwater containing K, Na, Cl, and O2 , and that it is now stagnant below the 4° C depth. In this lower zone Ca, Mg, CO2, and SiO2 are diffusing upwards from the lake bed, possibly partly released by anaerobic biological activity.

The variability in ice conditions over a lake and between lakes is studied. The effect of snow and snow drift on ice growth is theoretically discussed and quantified. Heat flow from the lake water to the underside of the ice and melting from the upper surface are also discussed quantitatively. Observations of spatial variability in late February and early March are reported from eleven lakes in central Sweden. The standard deviation of total ice thickness for many of the lakes is only 1 cm. The highest deviation reported is 5 cm. However, the distribution between white ice and black ice shows a larger variation. White ice tends to form more extensively near shores and black ice more extensively in central parts of lakes. When ice thickness over four years on five lakes in a river basin is compared, it seems that the total ice thickness from one single lake is fairly representative of lake ice cover in a region.