7 research outputs found
Dynamics of polynya in the River Ob Bay and predicting of its location
Get PDFDynamics of the ice edge of (flaw lead) a large polynya in the River Ob Bay was investigated over the period 1997–2016 on the basis of satellite data. More than 800 satellite images were analyzed during the investigation. Relationship between the obtained time series of changing latitude of the ice edge and time series of air temperature, wind and indices of Wangenheim–Girs, the Arctic Oscillation (AO), and North Atlantic Oscillation (NAO) was studied by means of the correlation analysis. The statistical analysis made it possible to reveal that southern position of the ice edge in autumn indicated to warmer winter months. Boundaries of the polynya during every next decade were identically determined by its position during the preceding period, and therewith the pronounced trend of the ice edge shift to south was noticed in 1997–2012. In addition, periodic fluctuations with two different periods were found against the background of trend. During 1996– 2006 the fluctuations were quasi-biennial while after 2006 the period of fluctuations increased up to 4–5 years. Effort to predict the ice edge position aimed at determination of the polynya boundaries in January-February of 2016 was undertaken; data on the air temperature and latitude of the ice edge position for preceding period were used as the predictors. The difference between the prediction and actual data was equal to 0.01 ÷ −0.43 of latitude with the average value for six decades equal to 0.11°. Analysis of inter-annual variability of the edge position indicated that the most close relationship took place with the Vangenheim–Girs index E in May (coefficient of correlation r = −0.73). Maximal values of r exceeding ±0.7 were calculated for the Arctic Oscillation indices in February with a positive shift of one year. When investigating long-term large-scale changes of climatic parameters, analysis of anomalies of average latitude values of the polynya southern boundary had been performed. This allowed to reveal that period of 2005–2006 was a point of inflection. This substantiates the known thesis (conclusion) that a well developed polynya exerts the warming effect on adjacent territories
Long-term changes in ice coverage in the area of the Svalbard (Spitsbergen) and Franz Josef Land archipelagos
Get PDFA comparative analysis of inter-annual changes in ice coverage and time scales of its variability in the waters surrounding the Svalbard and Franz Josef Land archipelagos has been performed. The analysis was carried out for the selected quasi-homogeneous regions. Open sources of information (satellite observations) collected by the Arctic and Antarctic Research Institute were used. Seasonal and inter-annual changes in ice coverage were studied over the period 1979–2019, since the uniform series of the satellite data were available for this period. The change of a relatively stable type of ice regime to a regime with a high level of inter-annual variability, which occurred in 2004–2006, was established. A significant negative trend in the change in ice coverage, characteristic of the waters surrounding both archipelagos, was revealed. Correlation and spectral analyses were used to estimate possible periods of cyclic fluctuations in ice coverage (taking into account the limited duration of the observation series), which amounted about 5–6 years. An efforts were made to establish possible relationships between the ice coverage fluctuations and the main atmospheric and oceanic indices. Essentially, no statistical connection with the main atmospheric indices (Arctic and North Atlantic Oscillations) was found, but the feedback with the Atlantic Multi-decadal Oscillation index had been established. The maximum correlation coefficients for Spitsbergen are observed in the winter season, while in the area of Franz-Joseph Land this takes place in summer, which may be attributed to the final velocity of the Atlantic Multidecadal Oscillation signal
Characteristics of Symmetric and Asymmetric Fission Modes as a Function of the Compound Nucleus Excitation in the Proton-Induced Fission of Pa, Np and Am
No full textInternational audienceAverage preequilibrium average statistical prescission and postscission neutron multiplicities as well as average gamma-ray multiplicity , average energy emitted by gamma-rays and average energy per one gamma quantum as a function of mass and total kinetic energy (TKE) of fission fragments were measured in the proton-induced reactions p+^{232}Th \to ^{233}Pa, p+^{238}U \to ^{239}Np and p+^{242}Pu \to ^{243}Am (at proton energy E_p=13, 20, 40 and 55 MeV). The fragment mass and energy distributions (MEDs) have been analyzed in terms of the multimodal fission. The decomposition of the experimental MEDs onto the MEDs of the distinct modes has been fulfilled in the framework of a method that is free from any parameterization of the distinct fission mode mass distribution shapes. The main characteristics for symmetric and asymmetric modes have been studied in their dependence on the compound nucleus composition and proton energy. The manifestation of multimodal fission in average gamma-ray multiplicities of fission fragments was also studied in this work
Динамика кромки заприпайной полыньи в Обской губе и прогноз её широтного положения
Get PDFDynamics of the ice edge of (flaw lead) a large polynya in the River Ob Bay was investigated over the period 1997–2016 on the basis of satellite data. More than 800 satellite images were analyzed during the investigation. Relationship between the obtained time series of changing latitude of the ice edge and time series of air temperature, wind and indices of Wangenheim–Girs, the Arctic Oscillation (AO), and North Atlantic Oscillation (NAO) was studied by means of the correlation analysis. The statistical analysis made it possible to reveal that southern position of the ice edge in autumn indicated to warmer winter months. Boundaries of the polynya during every next decade were identically determined by its position during the preceding period, and therewith the pronounced trend of the ice edge shift to south was noticed in 1997–2012. In addition, periodic fluctuations with two different periods were found against the background of trend. During 1996– 2006 the fluctuations were quasi-biennial while after 2006 the period of fluctuations increased up to 4–5 years. Effort to predict the ice edge position aimed at determination of the polynya boundaries in January-February of 2016 was undertaken; data on the air temperature and latitude of the ice edge position for preceding period were used as the predictors. The difference between the prediction and actual data was equal to 0.01 ÷ −0.43 of latitude with the average value for six decades equal to 0.11°. Analysis of inter-annual variability of the edge position indicated that the most close relationship took place with the Vangenheim–Girs index E in May (coefficient of correlation r = −0.73). Maximal values of r exceeding ±0.7 were calculated for the Arctic Oscillation indices in February with a positive shift of one year. When investigating long-term large-scale changes of climatic parameters, analysis of anomalies of average latitude values of the polynya southern boundary had been performed. This allowed to reveal that period of 2005–2006 was a point of inflection. This substantiates the known thesis (conclusion) that a well developed polynya exerts the warming effect on adjacent territories.На основе спутниковых данных рассматривается динамика кромки заприпайной полыньи в Обской губе за период 1997–2016 гг. Граница полыньи в каждую последующую декаду почти однозначно определялась её положением в предшествующий период. Анализ межгодовой изменчивости положения кромки показал, что наибольшая связь прослеживается с индексом Вангенгейма–Гирса Е в мае. Максимальные значения r, превышающие ±0,7, получены для февральских индексов Арктической осцилляции со сдвигом на один год
Многолетние изменения ледовитости в районе архипелагов Шпицберген и Земля Франца-Иосифа
Get PDFA comparative analysis of inter-annual changes in ice coverage and time scales of its variability in the waters surrounding the Svalbard and Franz Josef Land archipelagos has been performed. The analysis was carried out for the selected quasi-homogeneous regions. Open sources of information (satellite observations) collected by the Arctic and Antarctic Research Institute were used. Seasonal and inter-annual changes in ice coverage were studied over the period 1979–2019, since the uniform series of the satellite data were available for this period. The change of a relatively stable type of ice regime to a regime with a high level of inter-annual variability, which occurred in 2004–2006, was established. A significant negative trend in the change in ice coverage, characteristic of the waters surrounding both archipelagos, was revealed. Correlation and spectral analyses were used to estimate possible periods of cyclic fluctuations in ice coverage (taking into account the limited duration of the observation series), which amounted about 5–6 years. An efforts were made to establish possible relationships between the ice coverage fluctuations and the main atmospheric and oceanic indices. Essentially, no statistical connection with the main atmospheric indices (Arctic and North Atlantic Oscillations) was found, but the feedback with the Atlantic Multi-decadal Oscillation index had been established. The maximum correlation coefficients for Spitsbergen are observed in the winter season, while in the area of Franz-Joseph Land this takes place in summer, which may be attributed to the final velocity of the Atlantic Multidecadal Oscillation signal.На основе спутниковых данных выполнен сравнительный анализ ледовых условий в водах, омывающих архипелаги Земля Франца-Иосифа и Шпицберген. Исследуются сезонная и многолетняя изменчивость ледовых условий, изменение ледовой обстановки, а также связь ледовых условий с основными океаническими и атмосферными индексами за 1979–2019 гг
КЛИМАТИЧЕСКИЕ ПОСЛЕДСТВИЯ ЭКСПАНСИИ ПРЕСНЫХ ВОД В ГРЕНЛАНДСКОЕ МОРЕ И СЕВЕРНУЮ АТЛАНТИКУ
No full textIn second part of XX century there are three valuable salinity anomalies in North Atlantic, so-called «The Great Salinity Anomaly» (GSA), which can be characterized as a large, near-surface pool of fresher water [31–33, 36, 37]. There are GSA’70s, GSA’80s and GSA’90s. Dickson [37] described this event as one of dramatic and prolonged changes in ocean’s climate in XX century. In this paper, we have shown genesis of GSA’70s connected with ice production in Arctic flaw leads. Formation of GSAs’ in 1980s and 1990s has, at least, two main reasons. First is fresh water pools and huge amounts of ice carried out fromArcticBasin. The second one is recirculation of previous salinity anomaly inSubarcticBasin. Phenomenological model of climate change formation in polar and subpolar zone of North Hemisphere is presented in the paper. Examination conditions of previous GSA’s appearance and analysis of valuable fresh water intrusions in North Atlantic allow us to conclude that conditions for GSA’2010s are formed already and started to propagate inNorth Atlantic. For the first time we described GSA during its appearance, not post factum. Thus, we are standing at the break point of relatively long cooling inArctic.Во второй половине ХХ в. в Северной Атлантике отмечено три значимых аномалии распреснения поверхностных вод. В иностранной литературе они получили собственное имя – Великая соленосная аномалия (ВСА) [31–33, 36, 37]. Выделяют ВСА-1970-х, ВСА-1980-х и ВСА-1990-х годов. Р. Диксон [37] описал это явление как одно из наиболее резко и продолжительно влияющих на изменения климата океана в ХХ в. По мнению авторов настоящей статьи, генезис ВСА-1970-х связан с ледопродуктивностью арктических заприпайных полыней. В этой статье даётся феноменологическая модель формирования климатических изменений в зоне полярных и умеренных широт Северного полушария, обусловленных периодическими выбросами в Северную Атлантику аномально больших объёмов распреснённых вод из Северного Ледовитого океана. Делается вывод, что в настоящий момент уже сформировалась ВСА-2010-х и началось её распространение в Северной Атлантике. Впервые аномалия описывается не постфактум, а в момент зарождения. Таким образом, мы стоим на пороге достаточно длительного периода похолодания
