An Assessment of Sea Ice Motion Products in the Robeson Channel Using Daily Sentinel-1 Images

Sea ice motion is an essential parameter when determining sea ice deformation, regional advection, and the outflow of ice from the Arctic Ocean. The Robeson Channel, which is located between Ellesmere Island and northwest Greenland, is a narrow but crucial channel for ice outflow. Only three Eulerian sea ice motion products derived from ocean/sea ice reanalysis are available: GLORYS12V1, PSY4V3, and TOPAZ4. In this study, we used Lagrangian ice motion in the Robeson Channel derived from Sentinel-1 images to assess GLORYS12V1, PSY4V3, and TOPAZ4. The influence of the presence of ice arches, and wind and tidal forcing on the accuracies of the reanalysis products was also investigated. The results show that the PSY4V3 product performs the best as it underestimates the motion the least, whereas TOPAZ4 grossly underestimates the motion. This is particularly true in regimes of free drift after the formation of the northern arch. In areas with slow ice motion or grounded ice floes, the GLORYS12V1 and TOPAZ4 products offer a better estimation. The spatial distribution of the deviation between the products and ice floe drift is also presented and shows a better agreement in the Robeson Channel compared to the packed ice regime north of the Robeson Channel.

Summer coastal rookeries and perspectives of the Baikal seal (Pusa sibirica) population in the conditions of the global warming

Based on the secondary literature, a retrospective characterization of the climate in the Baikal region, starting from the end of the Pleistocene, is given. According to satellite monitoring data, the characteristics of the ice regime of the Lake Baikal in the conditions of climate warming are presented. Moreover, we briefly discuss the impact of climate change on the ecology and biology of the Baikal seal (Pusa sibirica Gm.). Using video materials obtained online at one of the main island coastal rookeries of seals (on the island of Tonkyi, the archipelago of the Ushkany Islands, Lake Baikal) in 2011–2017, the dependence of the number of seals hauled out on the lake level and the peculiarities of the fishing regime was determined (the survey was conducted from May–June to October). A direct relationship was determined between the relative number of animals that had a moulting delay and the ice regime of a given year: the longer the floating ice in the northern part of Lake Baikal remained, the more numerous were the first approaches of seals to the studied rookery and the greater was the proportion of moulting individuals. It is reasonable to assume that the main reason for the Baikal seal to come ashore is not prolongued moulting time, but a physiological need for sunlight, which has a healing effect on the body of animals that lack solar radiation in winter. In general, climate warming has a negative impact on the state of the Baikal seal population. The available paleoclimatic reconstructions of the Holocene indicate that the population of the Baikal seal has experienced a lot of climate changes in its history. Nevertheless, if the current trends of climatic changes persist until the end of the 21st century, the ecology and biology of the seal will drastically change (up to the beginning of terrestrial reproduction), and the population will significantly decrease. However, the Baikal seal as a species would remain.

Analysis of ice conditions of year-round navigation of Arc7 vessels in the southwestern part of the Kara Sea

Since 2006, a new generation of reinforced ice class Arc7 vessels has been operating on the Northern Sea Route. Safe and efficient sailing of this type of vessels in sea ice demands a detailed study of ice conditions. Accumulation and analysis of data on ice and hydrometeorological conditions for the entire Arctic in comparison with ice conditions along the route of vessels is an essential part of the development of optimal variants and optimal routes for ice navigation.The main aim of the study was to generalize the conditions of ice navigation of Norilskiy Nickel vessels along the optimal navigational routes in the south-western part of the Kara Sea. Based on the reports on sailing obtained from vessels of the “Norilskiy Nickel” type for the 2006–2014 period, we calculated the probability of choosing the optimal route along the Murmansk – Dudinka passage: through the Kara Gate Strait (seaward, central or coastal route) or the north of Cape Zhelaniya. During the year, vessels move predominantly through the Kara Gate. However, for three month per year, from April to June, the most appropriate route lies to the north of the Zhelaniya Cape. In April – May it is, on average, every second navigation, and in June – more than 80 % of all navigation. The features of the ice regime determining the choice of the specific navigation route, are described. The speeds of vessels of the “Norilskiy Nickel” type along various navigation routes in drifting sea ice of the Kara Sea are calculated. The fastest speed in drifting ice was recorded in the winter navigations of 2007–2008 and 2011–2012, in the January-May of these years the average speed was 10.2 and 11.2, correspondingly. The minimum speed in these years, even during the months of maximum ice cover growth, was not less than 4.8 knots. In other years, the average speeds were in the range of 9.2–9.8 knots. During the whole period of study, ice conditions that were extremely difficult for navigation formed three times: at the end of May 2009, at the end of March 2010 and in the middle of March 2011, these are considered in more detail in the present article.

ICE REGIME IMPACT ON THE COASTAL ZONE OF THE AZOV SEA

Azov is freezing sea it means that forecast of the time of the beginning and the end of ice fields formation needs. The ice condition limited of maritime safety. Modern condition of ice regime in the Azov Sea has been considered. The navigation of the Ukrainian ports Berdjansk and Mariupol depends on ice regime, duration and ice cover thickness. For the passage of vessels along the sea approach channels and recommended courses in the winter, the use of icebreakers is required. The demolition of confining buoys by ice fields and their restoration is reflected in the economic opportunities of the ports. Purpose of the article is to establish the characteristic winter periods of the last decade, taking into account the climatic changes for the rational using of the results of the impact on the economic activity of the marine infrastructure and hydrographic services. The specific purpose of this publication is to evaluate the displacement of the means of navigation equipment – buoys in the winter, taking into account meteorological factors. The authors set the following tasks: 1) to identify periods and vectors of buoys; 2) to define wind and ice characteristics in separate periods; 3) to reveal the basic meteorological cause of the movement of the buoys. It is important to note that there are no similar publications concerning this region. It became very actual after the climate change period was marked. The reserach is based on the data of direct and remote observations, the dates of ice formation in the area of seaports of Ukraine (Berdyansk and Mariupol) the characteristics of ice, the end of freezing, the opening and clearing of ice from the water areas of ports and bays and using the information from NAVTEX warning system, the archival materials of the weather site meteo.ua. The features of the physicochemical properties of sea water during ice formation and the general circulation of the waters of the Azov Sea are examined, which is linked with the influence of fresh runoff of Don and Kuban rivers. In the period 2013–2021 the observations were made on the displacement of navigation aids (buoys) during the winter periods from the approach channels of the port of Mariupol and Berdjansk as well as noticed buoys from the Azov-Don Marine Channel (Russian Federation). The characteristic of winter periods and conditions during the last decade are considered taking into account the influence of climatic changes. It is noted that the ice regime of the Sea of Azov is closely related with the sum of average daily air tem peratures over the sea for the season and wind power. According to this criterion, winters are usually divided into three types: severe, moderate and mild. Over the past 30 years, there were only two severe winters in the Azov Sea in 2005–2006 and 2011–2012. During these winters, the Azov Sea was completely ice covered. The influence of the ice regime to the coastal zone was examined, because it is very important for the industrial and economic needs of state building. To maintain the safety of navigation and reduce economic losses, it is necessary to consider the possibility of removing buoys, which are most often displaced by ice drift. Long-term average observations indicate the beginning of ice formation in Mariupol on December 14, and in Berdyansk on December 20. The Taganrog Bay and the ice accumulation areas are cleared of ice most recently – March 20–28. Under modern climatic changes (increasing the frequency of mild winters, actual costs for the operation of ships, hydrographic, icebreakers, etc.) are expected to be an order of magnitude lower than standard indicators.

The air temperature variability during the cold period on the Kola Peninsula as modification factor of the ice regime

The paper considers the long-term spatial and temporal air temperature variability on the Kola Peninsula according to 26 hydro-meteorological stations and the ice regime of rivers according to 13 hydrological stations for 1950—2018 (base period 1950—1980, and control period 1981—2018). The cold season of the year on the Kola Peninsula lasts from October to the first decade of May, the average temperature for the season is –6.2°C. The average increase in air temperature during the cold season was 1.1 °C.

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

The 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.

Changes in the Thickness of Ice Cover on Water Bodies Subject to Human Pressure (Silesian Upland, Southern Poland)

The paper discusses the reasons behind the variation in the thickness of ice on 39 anthropogenic water bodies located in the Silesian Upland (southern Poland). The studies were conducted over the course of three consecutive winter seasons. The measurements and observations were scheduled every 2 days during the freezing and ablation of the ice, and every 4 days when ice cover was present. Each time the thickness of the ice cover and the snow layer covering it were measured. The results show that the 35 water bodies studied are characterized by a similar—quasi-natural—ice regime, in which ice thickness variation depends mostly on the air temperature and the thickness of the snow layer covering the ice. The ice thickness on those water bodies does not significantly differ from that observed on lakes located in northern Poland, measuring on average from circa 4 to 21 cm, and with maximum thicknesses ranging from circa 14 to 40 cm, depending on the season. Four water bodies are characterized by different ice conditions; in their case the average and maximum ice thickness was significantly lower. In the Niezdara N water body this was caused by the inflow of warmer potamic water (quasi-natural regime), whereas in Pod Borem, Sośnicka, and Somerek it was caused by discharges of warm mine water (anthropogenic regime).

The potential of using Sentinel-1 and ALOS PALSAR-2 data for characterizing West Siberian lake ice backscatter anomalies

<p>Millions of lakes and ponds occupy large areas of the Arctic discontinuous and continuous permafrost zones. During most of the year, the surfaces of these lakes remain covered by a thick layer of ice. Synthetic Aperture Radar (SAR) data have shown to be useful for studying the ice on Arctic lakes, especially for monitoring lake ice phenology and the grounding state of the ice (ice frozen to the lakebed versus floating lake ice). Significant backscatter is often observed from the floating ice regime in C-band due to scattering on a rough ice-water interface.</p><p>Recent research has revealed features of anomalously low backscatter in Sentinel-1 C-band SAR imagery on some of the West Siberian lakes that likely belong to the floating ice regime. These anomalies are characterized by prominent shapes and sizes and seem to expand throughout late winter and/or spring. It is currently assumed that some of these features are related to strong emissions of natural gas (methane from hydrocarbon reservoirs), making it important to assess their origin in detail and understand the associated mechanisms. However, in-situ data are still missing.</p><p>Here, we assess the potential of the combined use of C-band Sentinel-1 (freely available) and L-band ALOS PALSAR-2 data  (available through JAXA PI agreement #3068002) to study the backscatter anomalies. We highlight the differences between observed backscatter from the two sensors with respect to different surface types (ground-fast lake ice, floating lake ice and anomalies) and investigate backscatter differences between frozen and melting conditions. Further, polarimetric classification is performed on L-band PALSAR-2 imagery, which reveals differences in scattering mechanisms between anomalies and floating lake ice.</p>