Tendencies of multi-year variability of the sea level at the coastal stations of the Аrctic оcean

2017 ◽  
pp. 51-66
Author(s):  
V. A. Merkulov ◽  
I. M. Ashik ◽  
L. А. Timokhov
Keyword(s):  
Sea Level ◽  
Climatic Conditions ◽  
The Arctic ◽  
Arctic Seas ◽  
Annual Average ◽  
Sea Level Fluctuations ◽  
Almost All ◽  
Freshwater River ◽  
Linear Trends

New estimates of linear trends in the position of the level surface were obtained as a result of analysis of the data of long-term observations of sea level fluctuations at the stations of the seas of the Arctic Ocean. A rise in sea level is observed at almost all stations. In multi-year fluctuations of the level, periods characterized by different values of linear trends are identified. The reasons for the variability of local linear trends in the level of the Arctic seas from the 1950-1980 stage to the 1990-2015 period are analyzed. It is shown that the presence of local trends during the annual average levels at coast stations is a consequence of changes in climatic conditions reflected in changes in atmospheric and hydrosphere climatic indices, as well as in freshwater river runoff.

Seasonal variability of tides in the Russian Arctic seas

2021 ◽  
Author(s):  
Mikhail Kulikov ◽  
Igor Medvedev
Keyword(s):  
Sea Level ◽  
Seasonal Variability ◽  
Arctic Region ◽  
The Arctic ◽  
Russian Arctic ◽  
Arctic Seas ◽  
Tidal Forces ◽  
Small Series ◽  
Tidal Characteristics

<p>In this research, the sea level variability in the Russian Arctic seas caused by the Moon and the Sun tidal forces is considered. For a long time, it was thought that the tides can be easily calculated based on a small series of observations made in summer, but as shown in a few recent publications, describing tides in the different parts of the Arctic Ocean, tidal characteristics change significantly during the year. The main attention is paid to their seasonal variability in the seas of the Russian Arctic. The most interesting results have been obtained for the east sector of the Russian Arctic seas, where the tides were poorly known, and the long-term data from the tide gauges have been processed for the first time. We have used the long-term hourly sea-level data from several stations in the White, Kara, Laptev and Chukchi seas. The temporary coverage for the White Sea stations includes rather continuous sea-level records from 2004 to 2014 yrs. The maximum length of records made from 1981 to 2005 at the stations of the east sector of the Arctic was found at the Tiksi station. In this work we also analysed unique data obtained from the bottom pressure loggers installed on the Laptev-sea shelf in the period 2018-2020. The results of this study allow us to conclude that the classical harmonic analysis applied to the precomputation of tides does not provide an accurate estimate of the tidal characteristics in individual water areas in the Arctic. Accounting of the seasonal variability in the tidal characteristics will make it possible to clarify tidal maps important for navigation and coastal construction in the Arctic Region.</p>

Diatoms and aquatic palynomorphs in the sediments of the Eurasian Arctic seas and their significance for paleooceanological investigations in the Arctic

2019 ◽  
pp. 246-251
Author(s):  
Yelena I. Polyakova ◽  
Yekaterina I. Novichkova ◽  
Tatiana S. Klyuvitkina ◽  
Elizaveta A. Agafonova ◽  
Irina M. Kryukova
Keyword(s):  
Bering Sea ◽  
Surface Sediments ◽  
Sea Water ◽  
The Arctic ◽  
Marginal Filter ◽  
Arctic Seas ◽  
Hydrological Parameters ◽  
The Arctic Ocean ◽  
Long Term Studies

Presented the results of long-term studies of diatoms and aquatic palynomorphs in surface sediments of the Arctic seas and the possibility of their use for the reconstructions of paleocirculation water masses, advection of Atlantic and Bering sea water into the Arctic ocean, changes in the river runoff to the seas, sedimentary processes in the marginal filter of the largest rivers, seasonal sea ice cover and other hydrological parameters.

Periodically forced self-organization in the long-term evolution of planktic foraminifera

2001 ◽  
Vol 38 (2) ◽  
pp. 293-308 ◽  
Author(s):  
Andreas Prokoph ◽  
Anthony D Fowler ◽  
R Timothy Patterson
Keyword(s):  
Sea Level ◽  
Logistic Map ◽  
Late Eocene ◽  
Self Organization ◽  
Extinction Data ◽  
Sea Level Fluctuations ◽  
Global Sea Level ◽  
Extinction Events ◽  
The Impact

Wavelet transform and other signal analysis techniques suggest that the planktic foraminiferal (PF) long-term evolutionary record of the last 127 Ma can be attributed to complex periodic and nonlinear patterns. Correlation of the PF extinction pattern with other geological series favors an origin of the ~30 Ma periodicity and self-organization by quasi-periodic mantle-plume cycles that in turn drive episodic volcanism, CO2-degassing, oceanic anoxic conditions, and sea-level fluctuations. Stationary ~30 Ma periodicity and a weak secular trend of ~100 Ma period are evident in the PF record, even without consideration of the mass extinction at the K–T boundary. The 27–32 Ma periodicity in the impact crater record and lows in the global sea-level curve, respectively, are ~6.5 Ma and ~2.3 Ma out of phase with PF-extinction data, although major PF-extinction events correspond to the bolide impacts at the K–T boundary and in late Eocene. Another six extinction events correspond to abrupt global sea-level falls between the late Albian and early Oligocene. Self-organization in the PF record is characterized by increased radiation rates after major extinction events and a steady number of baseline species. Our computer model of long-term PF evolution replicates this SO pattern. The model consists of output from the logistic map, which is forced at 30 Ma and 100 Ma frequencies. The model has significant correlations with the relative PF-extinction data. In particular, it replicates singularities, such as the K–T event, nonstationary 2.5–10 Ma periodicities, and phase shifts in the ~30 Ma periodicity of the PF record.

Revising key parameters for long-term carbon cycle models

2021 ◽  
Author(s):  
Chloé M. Marcilly ◽  
Trond H. Torsvik ◽  
Mathew Domeier ◽  
Dana L. Royer
Keyword(s):  
Sea Level ◽  
Age Distribution ◽  
Silicate Weathering ◽  
Geological Time ◽  
Sea Levels ◽  
Climate Fluctuations ◽  
Climate Gradients ◽  
Sea Level Fluctuations ◽  
Temperature And Precipitation

<p>CO<sub>2</sub> is the most important greenhouse gas in the Earth’s atmosphere and has fluctuated considerably over geological time. However, proxies for past CO<sub>2 </sub>concentrations have large uncertainties and are mostly limited to Devonian and younger times. Consequently, CO<sub>2</sub> modelling plays a key role in reconstructing past climate fluctuations. Facing the limitations with the current CO<sub>2</sub> models, we aim to refine two important forcings for CO<sub>2</sub> levels over the Phanerozoic, namely carbon degassing and silicate weathering.</p><p>Silicate weathering and carbonate deposition is widely recognized as a primary sink of carbon on geological timescales and is largely influenced by changes in climate, which in turn is linked to changes in paleogeography. The role of paleogeography on silicate weathering fluxes has been the focus of several studies in recent years. Their aims were mostly to constrain climatic parameters such as temperature and precipitation affecting weathering rates through time. However, constraining the availability of exposed land is crucial in assessing the theoretical amount of weathering on geological time scales. Associated with changes in climatic zones, the fluctuation of sea-level is critical for defining the amount of land exposed to weathering. The current reconstructions used in<sub></sub>models tend to overestimate the amount of exposed land to weathering at periods with high sea levels. Through the construction of continental flooding maps, we constrain the effective land area undergoing silicate weathering for the past 520 million years. Our maps not only reflect sea-level fluctuations but also contain climate-sensitive indicators such as coal (since the Early Devonian) and evaporites to evaluate climate gradients and potential weatherablity through time. This is particularly important after the Pangea supercontinent formed but also for some time after its break-up.</p><p>Whilst silicate weathering is an important CO<sub>2</sub> sink, volcanic carbon degassing is a major source but one of the least constrained climate forcing parameters. There is no clear consensus on the history of degassing through geological time as there are no direct proxies for reconstructing carbon degassing, but various proxy methods have been postulated. We propose new estimates of plate tectonic degassing for the Phanerozoic using both subduction flux from full-plate models and zircon age distribution from arcs (arc-activity) as proxies.</p><p>The effect of revised modelling parameters for weathering and degassing was tested in the well-known long-term models GEOCARBSULF and COPSE. They revealed the high influence of degassing on CO<sub>2</sub> levels using those models, highlighting the need for enhanced research in this direction. The use of arc-activity as a proxy for carbon degassing leads to interesting responses in the Mesozoic and brings model estimates closer to CO<sub>2 </sub> proxy values. However, from simulations using simultaneously the revised input parameters (i.e weathering and degassing) large model-proxy discrepancies remain and notably for the Triassic and Jurassic.</p><p> </p>

scholarly journals Amplified bioproductivity during Transition IV (332 000–342 000 yr ago): evidence from the geochemical record of Lake El'gygytgyn

2013 ◽  
Vol 9 (2) ◽  
pp. 679-686 ◽  
Author(s):  
L. Cunningham ◽  
H. Vogel ◽  
V. Wennrich ◽  
O. Juschus ◽  
N. Nowaczyk ◽  
...  
Keyword(s):  
Sharp Increase ◽  
Biogenic Silica ◽  
Ice Cores ◽  
Climatic Conditions ◽  
The Arctic ◽  
Significant Shift ◽  
Geochemical Parameters ◽  
Lake El’Gygytgyn ◽  
Arctic Russia

Abstract. To date, terrestrial archives of long-term climatic change within the Arctic have widely been restricted to ice cores from Greenland and, more recently, sediments from Lake El'gygytgyn in northeast Arctic Russia. Sediments from this lake contain a paleoclimate record of glacial-interglacial cycles during the last three million years. Low-resolution studies at this lake have suggested that changes observed during Transition IV (the transition from marine isotope stage (MIS) 10 to MIS 9) are of greater amplitude than any observed since. In this study, geochemical parameters are used to infer past climatic conditions thus providing the first high-resolution analyses of Transition IV from a terrestrial Arctic setting. These results demonstrate that a significant shift in climate was subsequently followed by a rapid increase in biogenic silica (BSi) production. Following this sharp increase, bioproductivity remained high, but variable, for over a thousand years. This study reveals differences in the timing and magnitude of change within the ratio of silica to titanium (Si/Ti) and BSi records that would not be apparent in lower resolution studies. This has significant implications for the increasingly common use of Si/Ti data as an alternative to traditional BSi measurements.

scholarly journals An introduction to causes and consequences of Cretaceous sea-level changes (IGCP 609)

2019 ◽  
Vol 498 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Michael Wagreich ◽  
Benjamin Sames ◽  
Malcolm Hart ◽  
Ismail O. Yilmaz
Keyword(s):  
Sea Level ◽  
Sea Level Changes ◽  
Short Term ◽  
Sea Level Fluctuations ◽  
Groundwater Aquifer ◽  
Sea Level Oscillations ◽  
Short And Long Term ◽  
Geological Timescale ◽  
Land Water

AbstractThe International Geoscience Programme Project IGCP 609 addressed correlation, causes and consequences of short-term sea-level fluctuations during the Cretaceous. Processes causing several ka to several Ma (third- to fourth-order) sea-level oscillations during the Cretaceous are so far poorly understood. IGCP 609 proved the existence of sea-level cycles during potential ice sheet-free greenhouse to hothouse climate phases. These sea-level fluctuations were most probably controlled by aquifer-eustasy that is altering land-water storage owing to groundwater aquifer charge and discharge. The project investigated Cretaceous sea-level cycles in detail in order to differentiate and quantify both short- and long-term records based on orbital cyclicity. High-resolution sea-level records were correlated to the geological timescale resulting in a hierarchy of sea-level cycles in the longer Milankovitch band, especially in the 100 ka, 405 ka, 1.2 Ma and 2.4 Ma range. The relation of sea-level highs and lows to palaeoclimate events, palaeoenvironments and biota was also investigated using multiproxy studies. For a hothouse Earth such as the mid-Cretaceous, humid–arid climate cycles controlling groundwater-related sea-level change were evidenced by stable isotope data, correlation to continental lake-level records and humid–arid weathering cycles.

Ample and recurrent sea-level fluctuations during the Bajocian: A hint towards middle Jurassic glacio-eustatism

2020 ◽  
Author(s):  
Stéphane Bodin ◽  
Jan Danisch ◽  
Malte Mau ◽  
Francois-Nicolas Krencker ◽  
Alexis Nutz ◽  
...  
Keyword(s):  
Sea Level ◽  
Middle Jurassic ◽  
Sediment Supply ◽  
Medium Term ◽  
High Atlas ◽  
Sea Level Fluctuations ◽  
R Packages ◽  
Central High ◽  
Central High Atlas

<p><span>Mesozoic sea-level fluctuations have been a matter of debate for several decades, especially the extend and origin of sea-level cycles that have a periodicity of about 1 Myr or less. The debate lies in the main driving mechanism for sequence development (global sea-level or sediment flux variations) as well as the reason behind water exchanges between the continents and the oceans (glacio- or aquifer-eustatism). In this study, we focus on the carbonate-dominated sedimentary record of the Bajocian (Middle Jurassic) in the Central High Atlas Basin of Morocco. Several aspects make this basin an appropriate location for discussing Middle Jurassic sea-level changes. Firstly, the outstanding exposures of the High Atlas Mountains, with continuous exposures for 10s of kilometres, allow to describe and track sedimentary packages and their bounding surfaces from proximal to distal settings. Moreover, a combination of ammonite and brachiopod biostratigraphy with carbon-isotopes chemostratigraphy allows to temporarily constrain their development, which permits to correlate and compare the Central High Atlas sedimentary record to other basins. Finally, due to high-subsidence rates, thick Bajocian sedimentary sequences have accumulated, minimizing condensation and hiatus that might prevail in other basins due to a lack of accommodation space creation. Two Bajocian long-term transgressive-regressive (T-R) packages are observed throughout the basin. They are modulated by several medium-term T-R packages, that have each an approximate duration of 1 Myr. These sequences can also be correlated on a basinwide scale. Combined with sedimentological and facies analyses, architectural evidence along proximal-to-distal transect illustrates that several of the medium-term sequences are characterized by the presence of a falling stage and lowstand systems tracts, demonstrating that medium-term T-R stacking patterns are not solely linked to fluctuation in sediment supply, but also to episodes of relative sea-level fall of at least 30m of amplitude. This is confirmed by backstripping analysis performed in a composite section from the center of the Basin. Comparison with Bajocian deposits from France and Scotland, where good biostratigraphic dating is also available, shows that similar contemporaneous sea-level fall can be observed, highlighting their potential global character. The two long-term Bajocian sequences are more difficult to correlate on a global scale, suggesting that they are rather primarily linked to fluctuation in regional sediment supply or dynamic topography processes. The exact cause of the Bajocian medium-term sea-level falls is currently unknown, but it is here interesting to note that a relatively cool globate climate has been postulated for the Middle Jurassic, suggesting that glacio-eustasy was their most likely driver.</span></p>

scholarly journals Long-term variability of dust events in Iceland (1949–2011)

2014 ◽  
Vol 14 (11) ◽  
pp. 17331-17358 ◽  
Author(s):  
P. Dagsson-Waldhauserova ◽  
O. Arnalds ◽  
H. Olafsson
Keyword(s):  
Sea Level ◽  
Dust Storms ◽  
The Arctic ◽  
Atmospheric Dust ◽  
Sea Level Pressure ◽  
Term Frequency ◽  
The World ◽  
Dust Events ◽  
The 1960S

Abstract. Long-term frequency of atmospheric dust observations was investigated for the southern part of Iceland and merged with results obtained from the Northeast Iceland (Dagsson-Waldhauserova et al., 2013). In total, over 34 dust days per year on average occurred in Iceland based on conventionally used synoptic codes for dust. Including codes 04–06 into the criteria for dust observations, the frequency was 135 dust days annually. The Sea Level Pressure (SLP) oscillation controlled whether dust events occurred in NE (16.4 dust days annually) or in southern part of Iceland (about 18 dust days annually). The most dust-frequent decade in S Iceland was the 1960s while the most frequent decade in NE Iceland was the 2000s. A total of 32 severe dust storms (visibility < 500 m) was observed in Iceland with the highest frequency during the 2000s in S Iceland. The Arctic dust events (NE Iceland) were typically warm and during summer/autumn (May–September) while the Sub-Arctic dust events (S Iceland) were mainly cold and during winter/spring (March–May). About half of dust events in S Iceland occurred in winter or at sub-zero temperatures. A good correlation was found between PM10 concentrations and visibility during dust observations at the stations Vik and Storhofdi. This study shows that Iceland is among the dustiest areas of the world and dust is emitted the year-round.

Chapter 5 Expansion South of the Arctic Seas, c. 1776-c. 1808

2004 ◽  
pp. 81-104
Author(s):  
Gordon Jackson
Keyword(s):  
Eighteenth Century ◽  
New England ◽  
American Revolution ◽  
The Arctic ◽  
Arctic Seas ◽  
Whale Oil ◽  
To Come ◽  
Almost All ◽  
New England Colonies ◽  
British People

For most people in the eighteenth century, and for most British people to this day, the whaling trade was synonymous with the Arctic voyages about which almost all the British whaling histories have been written. It is, however, important to remember that, despite its dramatic potential and home-spun quality, the Northern trade was no more than a subsidiary source of whale oil in the eighteenth century. Before 1770 it was rare for more than a tenth of peace-time imports to come from Greenland, and until the American Revolution the bulk of supplies came from the New England colonies. Imports from there averaged 3696 tuns in the years 1764-1775 compared with only 1168 tuns from Greenland....

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