История оледенения Арктического бассейна: взгляд из прошлого для оценки возможных изменений в будущем

The process of the sea ice formation in the Arctic Ocean is analyzed for the period of the last 65 million years, i.e. from the Paleocene to the present time. Appearance of sea ice in the high latitudes is demonstrated to be caused by the negative trend in global temperatures due to decreasing of the CO2 concentration in the ancient atmosphere. Formation of seasonal and perennial ice cover in the limited area near the Pole could take place during the mid-Neogene period, about 12–13 Ma ago. However, areas of the sea icing could be obviously changed for this time during periods of the climate warming and cooling. Permanent sea ice had been formed in the early Pleistocene, i.e. about 2.0–1.8 Ma ago only. Paleoclimatic reconstructions, based on the indirect data and modeling simulation for the Holocene optimum (10–6 ka ago) and for the Last Interglacial period (the isotopic substage in the marine cross-section 5e, about 125–127 ka ago) had shown that rising of global temperatures by 1.0–1.5 °C resulted in strong decreasing of the sea ice area, and the perennial ice cover became the seasonal one. Relatively small changes in the incoming solar radiation originating during the spring-summer time due to the orbital factors played the role of a trigger for onset of the melting process. Further on, the process could be enhanced owing to difference in the albedo between the ice cover and open water. Recently, the rapid shortening of the sea ice area is noted, and in some parts of the Arctic Ocean the area is twice cut down as compared with the normal. In 2015, the record low area of the winter sea ice was observed, and therewith the maximum of the ice area shifted to the earlier period (by 15 days) as compared with the period of 1981–2010. The winter fluctuations of the sea ice areas are as much important as the summer ones, since they are the best indicators of the present-day global warming. Thus, it can be supposed that some mechanism of replacing the perennial sea ice by the seasonal ones has been started up, that is the natural process of transition from seasonal ices to the next stage that is the ice-free Arctic. On the assumption that increasing of the CO2 concentration will continue despite the efforts to reduce emissions of greenhouse gases into the atmosphere, and the radiation forcing will approach to doubling of the CO2 content, one of the scenarios of the past can be realized now.Быстрое сокращение площади морских льдов в Арктике в последние десятилетия обусловлено их реакцией на повышение глобальной температуры. Морские льды – прекрасный индикатор состояния глобальной климатической системы как в историческое время, так и в отдалённом прошлом. Анализ исторических данных показывает, что современное сокращение площади и толщины морских льдов в Арктике беспрецедентно за последние 1450 лет. На основе синтеза морских, континентальных и других косвенных данных рассматривается история образования морского оледенения Арктики за последние 65 млн лет, от раннего палеогена до голоцена. Сокращение площади морских льдов в Арктике, уменьшение их толщины и увеличение площади одногодичного льда свидетельствуют, что запущен механизм замещения многолетних льдов сезонными. Это – естественное состояние перехода от сезонных льдов к следующему этапу – безлёдной Арктики

Two-qubit quantum photonic processor manufactured by femtosecond laser writing

We present an experimental implementation of a two-qubit photonic quantum processor fabricated using femtosecond laser writing technology. We employ femtosecond laser writing to create a low-loss reconfigurable photonic chip implementing precise single-qubit and two-qubit operations. The performance of single-qubit and two-qubit gates is characterized by full process tomography. An exemplary application of the processor to determining the ground state energy of an H2 molecule using the variational quantum eigensolver algorithm is demonstrated. Our results highlight the potential of femtosecond laser writing technology to deliver high quality small-scale quantum photonic processors.Comment: 20 pages, 15 figure

Морской лёд Арктического бассейна в свете современных и прошлых климатических изменений

Data from satellite observations (1979–2020) showed that over the last 40 years, years with a decrease in the area of summer ice extent and their thickness have prevail. Over 10 years, negative trends in anomalies of ice area and thickness of the ice are −13 and −15%, respectively. There is also a rapid reduction in the area of old ice (> 4 year-old): while in 1985 it was estimated at 2.7 million km2 while in March 2010 it was 0.34 million km2 . The paper analyses paleo-sea ice extent during the Holocene (the last 12,000 years) based on empirical biomarkers IP25 (a sea ice proxy with 25 carbon atoms synthesized by the specific Arctic sea ice diatoms Haslea spp. which have been proven to be a suitable proxy for paleo-sea ice reconstructions) obtained from deep-sea cores from the North Atlantic. The data obtained showed that during the warm periods of the Early and Middle Holocene, the area of summer sea ice was reduced to a minimum. This confirms the conclusion made earlier in [28] that the current trend of reducing the area and thickness of ice is unprecedented over the past 1,500 years. There is no complete analogue of the climate in the past corresponding to the current level of the CO2 concentration in the atmosphere. The closest time interval in terms of CO2 content is the warming of the Middle Pliocene between 3 and 4 million years ago, when the CO2 content in the atmosphere was 450–500 ppm against approximately 420 ppm at present. Paleo-climate reconstructions for this period estimate the global temperature to be 3.0–3.5±0.5 °C higher than at the end of the 19th century. Summer air temperatures in the high latitudes of the Northern Hemisphere exceeded the current ones by 8–10 °C, and the sea ice in the Arctic shelf seas was completely absent in the summer. Empirical data and model simulations have shown that presently the main driver of the reduction of the Arctic sea ice area is the increase in concentration of CO2 in the atmosphere. At the present time old sea ice tends to be replaced by seasonal ice demonstrating natural shift from predominance of permanent ice to the ice-free Arctic. In case of continuous increase in CO2 concentration in the atmosphere despite the emission control measures, one of the scenarios, which had happened in the past, may come true.За период спутниковых наблюдений (1979–2020 гг.) происходит постоянное уменьшение площади летних льдов и их толщины со скоростью 13 и 15% за 10 лет соответственно. Отмечается быстрое сокращение площади льдов старше четырёх лет и увеличение площади однолетних льдов. Анализ данных о состоянии морских льдов в Арктике за голоцен, за тёплую стадию последнего межледниковья и середину плиоцена показал, что в тёплые эпохи прошлого площадь летних льдов сокращалась до минимальных значений. Эмпирические данные и результаты моделирования показывают, что в настоящее время запущен механизм замещения многолетних льдов сезонными, что является естественным состоянием перехода от этапа преобладания сезонных льдов к безлёдной Арктики. Основной драйвер современного сокращения морских льдов  – рост содержания СО2. Если концентрация СО2 в атмосфере будет увеличиваться, то может сработать один из сценариев, имевший место в прошлом

Холодный эпизод около 8200 лет назад в Северной Европе: анализ эмпирических данных и возможных причин

Cold episode in Northern Europe happened about 8200 years ago was known for a relatively long time, mainly due to paleobotanical (palynological) data obtained from analysis of lake and peat sediments. Detailed analysis of ice cores from the Greenland holes GRIP, GISP2, and NGRIP with a time resolution of about 10 years made possible to refine the duration and characteristics of the time structure of this cold period. This cooling lasted for approximately 160 yr. Spore-pollen analysis of lake sediments in Northern Europe (Sweden, Finland, Denmark, Germany, the North and North-West of Russia) and deep-sea cores of the North Atlantic showed that the mean annual air temperature during the maximum stage of the cooling was reduced by 1–2 °C, and in some areas by more than 3 °C. The cold spread from the coast of the North Atlantic into the European continent and manifested itself mostly in Sweden, Finland, the Baltic States, and to a lesser extent in the North-West and West of the Russian Federation. In the central Russia and North of 70°N the cooling was weak or absent. The question about a nature of this cold event and other cold spells in Late Glaciation, known as the cold of the early, middle and late Dryas, is widely discussed in the scientific literature. Most of scientists accept a hypothesis proposed more than 20 years ago, that the reduction of air temperatures in regions immediately adjacent to the North Atlantic was caused by the large volume of melt water discharged into the ocean as a result of disintegration and melting of ice-sheets. Climate models that take into account these effects allow estimating a decrease in the air and sea surface temperature due to freshening (desalination) of the upper ocean layer, and this confirms that the greatest decrease in temperature should be observed in the regions directly adjacent to the ocean. The increase in global temperature over the last 30 years is estimated to be 0.8 ± 0.2 °C, which is already reflected in a noticeable increase in precipitation in high latitudes. In addition, the melting of mountain glaciers and sea ice in the Arctic basin promotes freshening of the upper ocean, and as a result of these processes one can expect a certain decrease in the air temperature in the high latitudes if the present-day climate warming will continue. On the basis of paleoclimatic data, it can be assumed that such a decrease in air temperature can be relatively small and occur only in areas directly adjacent to the North Atlantic.Уже более 20 лет в Северной Европе известен холодный эпизод около 8200 лет назад. Похолодание продолжалось около 160 лет, температуры воздуха снижались на 1–2 °С, а в отдельных районах – более чем на 3 °С. Предполагается, что снижение температур воздуха было связано с поступлением больших объёмов пресной воды в Северную Атлантику в результате распада и таяния ледников. Подобный механизм имеет прямое отношение к оценкам будущего климата при развитии современного глобального потепления. Поскольку таяние горных ледников и морских льдов в Полярном бассейне способствует опреснению верхнего слоя океана, при развитии потепления в районах, непосредственно прилегающих к Северной Атлантике, можно ожидать некоторого снижения температуры воздуха в высоких широтах

The atmospheric role in the Arctic water cycle: A review on processes, past and future changes, and their impacts

This is the final version of the article. Available from the publisher via the DOI in this record.Atmospheric humidity, clouds, precipitation, and evapotranspiration are essential components of the Arctic climate system. During recent decades, specific humidity and precipitation have generally increased in the Arctic, but changes in evapotranspiration are poorly known. Trends in clouds vary depending on the region and season. Climate model experiments suggest that increases in precipitation are related to global warming. In turn, feedbacks associated with the increase in atmospheric moisture and decrease in sea ice and snow cover have contributed to the Arctic amplification of global warming. Climate models have captured the overall wetting trend but have limited success in reproducing regional details. For the rest of the 21st century, climate models project strong warming and increasing precipitation, but different models yield different results for changes in cloud cover. The model differences are largest in months of minimum sea ice cover. Evapotranspiration is projected to increase in winter but in summer to decrease over the oceans and increase over land. Increasing net precipitation increases river discharge to the Arctic Ocean. Over sea ice in summer, projected increase in rain and decrease in snowfall decrease the surface albedo and, hence, further amplify snow/ice surface melt. With reducing sea ice, wind forcing on the Arctic Ocean increases with impacts on ocean currents and freshwater transport out of the Arctic. Improvements in observations, process understanding, and modeling capabilities are needed to better quantify the atmospheric role in the Arctic water cycle and its changes.We thank all colleagues involved in the Arctic Freshwater Synthesis (AFS) for fruitful discussions. In particular, John Walsh is acknowledged for his constructive comments on the manuscript. AFS has been sponsored by the World Climate Research Programme’s Climate and the Cryosphere project (WCRP-CliC), the International Arctic Science Committee (IASC), and the Arctic Monitoring and Assessment Programme (AMAP). The work for this paper has been supported by the Academy of Finland (contracts 259537 and 283101), the UK Natural Environment Research Council (grant NE/J019585/1), the US National Science Foundation grant ARC-1023592 and the Program “Arctic” and the Basic Research Program of the Presidium Russian Academy of Sciences. NCAR is supported by the U.S. National Science Foundation. We gratefully acknowledge the project coordination and meeting support of Jenny Baeseman and Gwenaelle Hamon at the CliC International Project Office. No new data were applied in the manuscript. Data applied for Figures 2 and 3 are available from the JRA-55 archive at http://jra. kishou.go.jp/JRA-55/index_en. html#usage

Влияние снежного покрова на промерзание и протаивание грунта на Западном Шпицбергене

This paper presents the results of experimental research of snow cover influence on ground freezing/thawing in Svalbard. Observations show that even before the snow disappearance ground thaws for dozens of centimeters that increases the thaw depth later in the season. Under the snow cover of 40 cm the thaw depth can reach 35–50 cm. The thawing can be caused by melt water with slightly positive temperature, percolating under the snow cover near the ground surface. The data on ground temperature regime during a year under various snow depths are given. Under a shallow snow cover the ground cools significantly, and this process causes the slowing down subsequent thawing.Рассматриваются результаты натурных измерений и расчётов влияния снежного покрова на промерзание и протаивание грунта на Западном Шпицбергене. Установлено, что ещё до схода снежного покрова грунт протаивает на десятки сантиметров, в результате чего увеличивается толщина талого слоя. Так, под снегом, толщиной 40 см, глубина протаивания грунта составляет 35–50 см. По мнению авторов, это может быть вызвано талой водой с небольшой положительной температурой, фильтрующейся под снежным покровом в приповерхностной части грунта

History of sea ice in the Arctic basin: Lessons from the past for future

The process of the sea ice formation in the Arctic Ocean is analyzed for the period of the last 65 million years, i.e. from the Paleocene to the present time. Appearance of sea ice in the high latitudes is demonstrated to be caused by the negative trend in global temperatures due to decreasing of the CO2 concentration in the ancient atmosphere. Formation of seasonal and perennial ice cover in the limited area near the Pole could take place during the mid-Neogene period, about 12–13 Ma ago. However, areas of the sea icing could be obviously changed for this time during periods of the climate warming and cooling. Permanent sea ice had been formed in the early Pleistocene, i.e. about 2.0–1.8 Ma ago only. Paleoclimatic reconstructions, based on the indirect data and modeling simulation for the Holocene optimum (10–6 ka ago) and for the Last Interglacial period (the isotopic substage in the marine cross-section 5e, about 125–127 ka ago) had shown that rising of global temperatures by 1.0–1.5 °C resulted in strong decreasing of the sea ice area, and the perennial ice cover became the seasonal one. Relatively small changes in the incoming solar radiation originating during the spring-summer time due to the orbital factors played the role of a trigger for onset of the melting process. Further on, the process could be enhanced owing to difference in the albedo between the ice cover and open water. Recently, the rapid shortening of the sea ice area is noted, and in some parts of the Arctic Ocean the area is twice cut down as compared with the normal. In 2015, the record low area of the winter sea ice was observed, and therewith the maximum of the ice area shifted to the earlier period (by 15 days) as compared with the period of 1981–2010. The winter fluctuations of the sea ice areas are as much important as the summer ones, since they are the best indicators of the present-day global warming. Thus, it can be supposed that some mechanism of replacing the perennial sea ice by the seasonal ones has been started up, that is the natural process of transition from seasonal ices to the next stage that is the ice-free Arctic. On the assumption that increasing of the CO2 concentration will continue despite the efforts to reduce emissions of greenhouse gases into the atmosphere, and the radiation forcing will approach to doubling of the CO2 content, one of the scenarios of the past can be realized now

The History of Punctuation Marks in Spanish

This article is devoted to the history of the evolution of punctuation marks in the Spanish language. Punctuation is one of the fundamental tools for the organization of written language. At the same time this system causes many difficulties in learning both in the mother tongue and in foreign language. Moreover, this aspect of the language system is often omitted in Russia. The authors of this article have the objective to show the stages in the development of punctuation, which emerged from the Greek interpunction and punctuation system in Latin, in the Spanish language. Basing its arguments on this assumption, the article also names the background of these changes (including extra-linguistic factors). The key moment in the history of the punctuation was the foundation of the Royal Spanish Academy that went into the codification of Spanish (Castilian) language. As a result, the punctuation norm was for the first time ever fixed and described for the whole Spanish country. For the same reason a lot of attention in the article is paid to the detailed analysis of the Orthography of the Spanish language starting with the edition of 1741 and finishing with the edition of 2010. The authors are confident that this article will be interesting for language experts, translators, teachers and for those who want to take an exam of DELE of C1 and C2 levels