Observations Of Ice Cover Research Articles

Use of Landsat Satellite Images in the Assessment of the Variability in Ice Cover on Polish Lakes

Despite several decades of observations of ice cover in Polish lakes, researchers have not broadly applied satellite images to date. This paper presents a temporal and spatial analysis of the variability in the occurrence of ice cover on lakes in the Drawskie Lakeland in the hydrological years 1984–2022 based on satellite data from Landsat missions 4, 5, 7, 8, and 9. The range of occurrence of ice cover was determined based on the value of the Normalised Difference Snow Index (NDSI) and blue spectral band (ρλblue). The determination of ice cover extent adopted ρλblue values from 0.033 to 0.120 as the threshold values. The analysis covered 67 lakes with an area from 0.07 to 18.71 km2. A total of 53 images were analysed, 14 and 39 out of which showed full and partial ice cover, respectively. The cluster analysis permitted the designation of two groups of lakes characterised by an approximate range of ice cover. The obtained results were analysed in the context of the morphometric parameters of the lakes. It was evidenced that the range of the ice cover on lakes is determined by the surface area of the lakes; their mean and maximum depth, volume, length, and width; and the height of the location above sea level. The results of analyses of the spatial range of ice cover in subsequent scenes allowed for the preparation of maps of probability of ice cover occurrence that permit the complete determination of its variability within each of the lakes. Monitoring of the spatial variability in ice cover within individual lakes as well as in reference to lakes not subject to traditional observations offers new research possibilities in many scientific disciplines focused on these ecosystems.

The influence of treated wastewaterfrom the Lodz city agglomeration on the ice regime and water temperature of the Ner river

AbstractThe study attempts to answer the following question: Does human impact contribute to changes recorded in the Ner river ice regime? In replying to this question, data on water consumption in Lodz (Łódź) (a city in central Poland) in 1951–2017 were used, as well as observations of ice cover and all ice phenomena for the same period. The ice regime and water temperature of the river have changed over the past 70 years. The changes result not only from changes caused by global warming but also from additional fluctuations in this temperature as determined by changes in the quantity and quality of wastewater discharged into the river from the Lodz city agglomeration. The frequency of ice phenomena in the river decreased, and their duration dropped by almost half. This tendency was compounded by a decrease in number of days with ice phenomena, which in turn was caused by a rapid increase in the amount of waste and thermally polluted waters supplied from Lodz. The river water temperature has now stopped increasing. The course of the river ice regime now resembles that of a natural watercourse again.

Winter Water Properties and the Chukchi Polynya

AbstractWater properties from moored measurements (2010–2015) near Icy Cape on the eastern Chukchi shelf have been examined in relation to satellite observations of ice cover. Atlantic Water (AW), with temperature >−1°C and salinity >33.6, has been observed to upwell from deeper than 200 m in the Arctic Basin onto the Chukchi Shelf via Barrow Canyon. Most previous observations of AW on the Chukchi shelf have been in or near Barrow Canyon; observations of AW farther onto the shelf are rare. Despite mooring location on the shelf ∼225 km from the head of Barrow Canyon, five AW events have been observed at mooring C1 (70.8°N, 163.2°W) in 4 years of data. All but one of the events occurred under openings in the sea‐ice cover (either a polynya or the ice edge). No events were observed during the winter of 2011/2012, a year with little polynya activity in the region. In addition to changes in temperature and salinity, the AW events are typically associated with southwestward winds and currents, changes in sea‐ice cover, and increased nutrient concentrations in the bottom water. Estimates of heat content associated with the AW events suggest that the Chukchi Polynya can often be classified as a hybrid sensible heat/wind‐driven polynya.

Comparative evaluation and comparability of satellite and airborne data on the ice content of the Sea of Okhotsk

Information on the sea ice coverage is one of the most important for the development of the Sakhalin shelf. The paper deals with the evaluation of ice extent estimations in the Sea of Okhotsk based on data of the remote sensing and aerial observations in winter seasons 1970–1991. The analysis has revealed the average seasonal difference in satellite and aerial ice series is 120.2 thousand km² (7.5% of the sea area). Ranges of changes of average values of a difference for a season has made from 18.5 to 265.6 square kilometers. The satellite and aerial sea ice extent data are strongly correlated (R = 0.96) with high significance for all period considered. The results obtained suggest that the series of observations of ice cover of the Sea of Okhotsk, made by different methods, have good comparability and can be used together to complement each other and produce an integrated and refined sea ice maps.

The fate of lake ice in the North American Arctic

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.

Bootstrap-based tests for trends in hydrological time series, with application to ice phenology data

Summary Studying trends in ice freeze-up and break-up dates as well as ice cover duration on lakes, which are sensitive to the air temperature, provides us useful information about climate change and linkages to atmospheric teleconnection patterns. Such data, however, typically show a positive serial correlation, which implies that a high/low observation tends to be followed by a high/low observation in the future. Such serial correlation among data is known to lead to deflation of p -values and related inflation of significance levels of most statistical procedures and tests, making the obtained results unreliable. In particular, we show that the classical statistical approaches, e.g., Student’s t - and Mann–Kendall tests, which assume independence of data, are inappropriate when a serial correlation is present. To overcome the problem, we suggest sieve bootstrap approaches which take into account the serial correlation of data for trend tracking in order to obtain more accurate and reliable estimates. We compare and discuss the results on the classical and newly proposed statistical approaches for the trend analysis using freeze-up and break-up dates as well as ice cover observations from Lake Baikal for the period 1869–1996 and Lake Kallavesi freeze-up dates data from 1834 to 1996. Remarkably, some recent studies of the Kallavesi freeze-up and the Baikal break-up dates, performed under the assumption of independence, report p -values that are relatively close to the border of statistical significance and, hence, provide some doubts in existence of a linear trend. In contrast, after taking into account the dependence structure of the observed data, the newly derived p -values have raised to an insignificant level, which implies no sufficient evidence for existence of a linear trend. The new bootstrap-based approaches also yield substantially less significant results for the existence of a trend for freeze-up dates and ice cover duration for Lake Baikal than reported earlier.

Climate change in Eurasian Arctic shelf seas: centennial ice cover observations

Arctic sea ice as an element of the global climate system.- Long-term changes in Arctic Seas ice extent during the twentieth century.- Variability of sea ice thickness and concentration in the twentieth century.- Consistency among sea ice extent and atmospheric and hydrospheric processes.- Possible causes of changes in climate and in Arctic Seas ice extent.- Assessment of possible changes in air temperature and sea-ice extent in the Arctic Seas in the twenty-first century.- Conclusions.

Perspectives of Northern Sea Route and Northwest Passage in the twenty-first century

The ability of modern climate models to simulate ice season length in the Arctic, its recent changes and navigation season on Arctic marine routes along the Eurasian and the North American coastlines is evaluated using satellite ice cover observations for 1979–2007. Simulated mean sea ice season duration fits remarkably well to satellite observations and so do the simulated 20th century changes using historical forcing. This provides confidence to extend the analysis to projections for the twenty-first century. The navigation season for the Northern Sea Route (NSR) and Northwest Passage (NWP), alternative sea routes from the North Atlantic to Asia, will considerably increase during this century. The models predict prolongation of the season with a free passage from 3 to 6 months for the NSR and from 2 to 4 months for the NWP by the end of twenty-first century according to A1B scenario of the IPCC. This suggests that transit through the NSR from Western Europe to the Far East may be up to 15% more profitable in comparison to Suez Canal transit by the end of the twenty-first century.

Observations of Lake Baikal ice from satellite altimetry and radiometry

We demonstrate the potential of combining satellite altimetry and radiometry for lake ice studies using the example of Lake Baikal in Siberia. We show the synergy using active and passive microwave observations available from the recent satellite altimetry missions (TOPEX/Poseidon, Jason-1, ENVISAT and Geosat Follow-On), complemented by the SSM/I passive data. We assess the applicability of altimetric and radiometric data for ice/water discrimination, and discuss the drawbacks and benefits of each type of sensor. An ice discrimination method, based on the combined use of the data from the four altimetric missions and SSM/I, is proposed and validated using available in situ observations and MODIS imagery. The method is applied to the entire satellite data set and used to define specific dates of ice events (first appearance of ice, formation of stable ice cover, first appearance of open water, complete disappearance of ice) and associated uncertainties. Using these satellite-derived estimates, we can extend the existing time series of ice events in the Southern Baikal up to 2004 and provide new information on the Middle and Northern Baikal, regions where no recent in situ ice cover observations are available. Our data show that over the last 10–15 years, trends towards earlier ice formation and later ice break-up result in a tendency for longer fast ice duration over the whole Lake Baikal. The methods proposed here have been tested for Lake Baikal, but they are applicable for other lakes and water bodies with seasonal ice cover.

Ice cover as an indicator of winter air temperature changes: case study of the Polish Lowland lakes

Observations of ice cover and winter air temperature measurements were carried out on six lakes in northern Poland during the period 1961–2000. Detailed analyses of the dates of formation and termination of the ice cover, the duration of maximum thickness and ice-free period during winter were carried out. Various tendencies were found in the time series of the earliest freeze-up dates, whereas the latest ice break-up dates were recorded to occur much earlier than in the past on all the lakes, with time advance being on average from 0.6 to 0.8 day year−1. The period with ice cover has been getting shorter at the rate of 0.8 to 0.9 day year−1, with the exception of Lake Hañcza, the deepest lake in the European Lowland, where the rate of 0.4 day year−1 was recorded. Similarly, there was a decreasing tendency in the maximum thickness of the ice cover, at the rate of 0.26 to 0.60 cm year−1. Despite similar tendencies, all those changes showed diverse dynamics in particular lakes. The proposed indicator of the ice cover stability confirms the above statements, and thus, the undergoing climatic changes.

Variability of physical and chemical characteristics along the 70-m isobath of the southeastern Bering Sea

From observations of ice cover, temperature, salinity, currents and nitrate, it is evident that along-shelf variability was significant over the middle shelf of the eastern Bering Sea, but less distinct than that observed in the cross-shelf domains. Along the 70-m isobath, three zones were evident in the summer: the southeastern cold pool (centered at ∼57°N); an intermediate zone, consisting of warmer water, with weaker stratification; and the northern cold pool, extending northward from 58°N. Small-scale (∼20 km) horizontal features that persisted for months were common. Nutrient concentrations were related to salinity and were replenished more uniformly over the southern shelf, than north of the Pribilof Islands. Although mean currents were weak (∼1 cm s −1 ), short energetic advective events impacted the temperature and salinity structure.