scholarly journals Features of Seasonal Sea Level Oscillations in the Russian Arctic Seas

Oceanology ◽  
2021 ◽  
Author(s):  
I. P. Medvedev
Keyword(s):  
Sea Level ◽  
Barents Sea ◽  
Extreme Values ◽  
Mean Amplitude ◽  
Arctic Seas ◽  
Lena River ◽  
Sharp Maximum ◽  
Sea Level Oscillations ◽  
The Mean ◽  
Seasonal Oscillations

Abstract Based on the analysis of long series of monthly mean sea level values from the database of the PSMSL and ESIMO portals, we obtained estimates of the mean and extreme amplitudes of seasonal oscillations. The mean amplitude of annual sea level oscillations in the White Sea is 7 cm, in the Barents Sea is 9–10 cm, in the Kara Sea, is 8–9 cm, in the Laptev Sea, is 10–11 cm, in the East Siberian and Chukchi seas is 13–14 cm. In the estuarine areas of seas, the amplitude of annual oscillations increases, and the semiannual, third-annual, and quarter-annual components appear in the sea level spectra. They are formed due to the asymmetry of the seasonal sea level variation with a sharp maximum during the flood period in June. Interannual changes in the amplitude of seasonal oscillations were identified and estimates of their extreme values were obtained. In some years, the amplitude of seasonal oscillations reaches 50 cm in the Yenisei Gulf and Gulf of Ob, 60 cm near the mouth of the Lena River, and 75 cm at the mouth of the Olenek River.

scholarly journals Sea-level variations on the north and northwest coasts of Spain

2012 ◽  
Vol 69 (5) ◽  
pp. 720-727 ◽  
Author(s):  
María Jesús García ◽  
Elena Tel ◽  
Joaquín Molinero
Keyword(s):  
Sea Level ◽  
North Atlantic ◽  
Extreme Values ◽  
Mean Sea Level ◽  
Sea Levels ◽  
The North ◽  
Glacial Rebound ◽  
Sea Level Variations ◽  
The Mean ◽  
Range Of Variation

Abstract García, M. J., Tel, E., and Molinero, J. 2012. Sea-level variations on the north and northwest coasts of Spain. – ICES Journal of Marine Science, 69: 720–727. An exhaustive analysis of historical sea-level records at three stations located along the northern and northwestern Spanish coast has permitted a description of the mean sea-level trend over the past 67 years. The analysis also produced results on the type, amplitude, and propagation of tides, as well as on the range of variation in the sea level, extreme values, and return periods. Once corrected for the Post Glacial Rebound, the rise in the mean sea level was estimated at 2.38, 2.45, and 2.65 mm year−1 in Santander, A Coruña, and Vigo, respectively. The meteorological contribution is evaluated by the winter North Atlantic Oscillation index, producing a correlation of −0.658 with the empirical orthogonal function mode 1, which explained 81.86% of the total variance of winter (from December to March) mean sea levels. Harmonic analysis evidenced the semi-diurnal nature of the tide and showed that the amplitude and propagation of the M2 tidal wave followed the North Atlantic regional pattern, with decreasing amplitudes and phases from east to west. Hourly height levels were run through an extreme analysis and resulted in maximum sea-level values over the respective mean sea levels (datum): 2.55, 2.48, and 2.51 m in Santander, A Coruña, and Vigo, respectively. The estimated extreme levels for a 120-year return period exceeded the observed maxima in the three locations by 0.25, 015, and 0.10 m, respectively.

scholarly journals Surface currents in the Porsanger fjord in northern Norway

2016 ◽  
Vol 37 (3) ◽  
pp. 337-360 ◽  
Author(s):  
Malgorzata Stramska ◽  
Andrzej Jankowski ◽  
Agata Cieszyńska
Keyword(s):  
Sea Level ◽  
Barents Sea ◽  
Surface Current ◽  
Current Data ◽  
Tidal Range ◽  
Surface Currents ◽  
Tidal Component ◽  
Level Data ◽  
Sea Level Oscillations ◽  
Tidal Constituents

Abstract We describe surface currents in the Porsanger fjord (Porsangerfjorden) located in the European Arctic in the vicinity of the Barents Sea. Our analysis is based on surface current data collected in the summer of 2014 using High Frequency (WERA, Helzel Messtechnik GmbH) radar system. One of our objectives was to separate out the tidal from the nontidal components of the currents and to determine the most important tidal constituents. Tides in the Porsanger fjord are substantial, with tidal range on the order of about 3 m. Tidal analysis attributes to tides about 99% of variance in sea level time series recorded in Honningsvaag. The most important tidal component in sea level data is the M2 component, with amplitude of ~90 cm. The S2 and N2 constituents (amplitude of ~20 cm) also play a significant role in the semidiurnal sea level oscillations. The most important diurnal component is K1 with amplitude of about 8 cm. The most important tidal component in analyzed surface currents records is the M2 component. The second most important component is the S2. Our results indicate that in contrast to sea level, only about 10-30% of variance in surface currents can be attributed to tidal currents. This means that about 70-90% of variance is due to wind-induced and geostrophic currents.

Long-term dynamics and destruction of marsh vegetation in the Kolokolkova Bay of the Barents Sea

2012 ◽  
pp. 66-77 ◽  
Author(s):  
I. A. Lavrinenko ◽  
O. V. Lavrinenko ◽  
D. V. Dobrynin
Keyword(s):  
Species Composition ◽  
Plant Communities ◽  
Barents Sea ◽  
Mean Value ◽  
Marsh Vegetation ◽  
Composition And Structure ◽  
The Mean ◽  
Species Composition And Structure

The satellite images show that the area of marshes in the Kolokolkova bay was notstable during the period from 1973 up to 2011. Until 2010 it varied from 357 to 636 ha. After a severe storm happened on July 24–25, 2010 the total area of marshes was reduced up to 43–50 ha. The mean value of NDVI for studied marshes, reflecting the green biomass, varied from 0.13 to 0.32 before the storm in 2010, after the storm the NDVI decreased to 0.10, in 2011 — 0.03. A comparative analysis of species composition and structure of plant communities described in 2002 and 2011, allowed to evaluate the vegetation changes of marshes of the different topographic levels. They are fol­lowing: a total destruction of plant communities of the ass. Puccinellietum phryganodis and ass. Caricetum subspathaceae on low and middle marches; increasing role of halophytic species in plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. typicum on middle marches; some changes in species composition and structure of plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. festucetosum rubrae on high marches and ass. Parnassio palustris–Salicetum reptantis in transition zone between marches and tundra without changes of their syntaxonomy; a death of moss cover in plant communities of the ass. Caricetum mackenziei var. Warnstorfia exannulata on brackish coastal bogs. The possible reasons of dramatic vegetation dynamics are discussed. The dating of the storm makes it possible to observe the directions and rates of the succession of marches vegetation.

NUMERICAL MODELING OF STORM SURGES, WIND WAVES AND FLOODING IN THE TAGANROG BAY

2017 ◽  
Author(s):  
Vladimir Fomin ◽  
Vladimir Fomin ◽  
Dmitrii Alekseev ◽  
Dmitrii Alekseev ◽  
Dmitrii Lazorenko ◽  
...  
Keyword(s):  
Sea Level ◽  
Wind Waves ◽  
Storm Surges ◽  
Atmospheric Model ◽  
Extreme Storm ◽  
Regional Atmospheric Model ◽  
Sea Level Oscillations ◽  
Flooding And Drying ◽  
Flooded Area ◽  
Taganrog Bay

Storm surges and wind waves are ones of the most important hydrological characteristics, which determine dynamics of the Sea of Azov. Extreme storm surges in Taganrog Bay and flooding in the Don Delta can be formed under the effect of strong western winds. In this work the sea level oscillations and wind waves in the Taganrog Bay were simulated by means of the coupled SWAN+ADCIRC numerical model, taking into account the flooding and drying mechanisms. The calculations were carried out on an unstructured mesh with high resolution. The wind and atmospheric pressure fields for the extreme storm from 20 to 28 of September, 2014 obtained from WRF regional atmospheric model were used as forcing. The analysis of simulation results showed the following. The western and northern parts of the Don Delta were the most flood-prone during the storm. The size of the flooded area of the Don Delta exceeded 50%. Interaction of storm surge and wind wave accelerated the flooding process, increased the size of the flooded area and led to the intensification of wind waves in the upper of Taganrog Bay due to the general rise of the sea level.

Quantitative analysis of static equilibrium in women after mastectomy

2014 ◽  
Vol 14 (1) ◽  
pp. 81-87
Author(s):  
Maciej Rachwał ◽  
Justyna Drzał-Grabiec ◽  
Katarzyna Walicka-Cupryś ◽  
Aleksandra Truszczyńska
Keyword(s):  
Mean Amplitude ◽  
Control Group ◽  
Foot Pressure ◽  
Locomotor System ◽  
Center Of Foot Pressure ◽  
The Mean ◽  
Almost All ◽  
Posture Stability ◽  
Mastectomy Group ◽  
Better Than

Abstract Background: The post-mastectomy changes to the locomotor system are related to the scar and adhesion or to the lymphatic edema after amputation which, in turn, lead to local and global distraction of the work of the muscles. These changes lead to body statics disturbance that changes the projection of the center of gravity and worsens motor response due to changing of the muscle sensitivity. Objective: The aim of the study was to evaluate the static balance of women after undergoing mastectomy. Methods: The study included 150 women, including 75 who underwent mastectomy (mean age: 60±7.6) years, mean body mass index (BMI): 26 (±3.6) kg/m2) and 75 who were placed in the control group with matched age and BMI. The study was conducted using a tensometric platform. Results: Statistically significant differences were found for almost all parameters between the post-mastectomy group and group of healthy women, regarding center of foot pressure (COP) path length in the Y and X axes and the mean amplitude of COP. Conclusions: First, the findings revealed that balance in post-mastectomy women is significantly better than in the control group. Second, physiotherapeutic treatment of post-mastectomy women may have improved their posture stability compared with their peers.

Growth of fingers at an unstable diffusing interface in a porous medium or Hele-Shaw cell

1969 ◽  
Vol 39 (3) ◽  
pp. 477-495 ◽  
Author(s):  
R. A. Wooding
Keyword(s):  
Porous Medium ◽  
Numerical Solutions ◽  
Hyperbolic Equations ◽  
Saturated Porous Medium ◽  
Mean Amplitude ◽  
Wave Number ◽  
Two Fluids ◽  
Averaged Equations ◽  
The Mean ◽  
Hele Shaw Cell

Waves at an unstable horizontal interface between two fluids moving vertically through a saturated porous medium are observed to grow rapidly to become fingers (i.e. the amplitude greatly exceeds the wavelength). For a diffusing interface, in experiments using a Hele-Shaw cell, the mean amplitude taken over many fingers grows approximately as (time)2, followed by a transition to a growth proportional to time. Correspondingly, the mean wave-number decreases approximately as (time)−½. Because of the rapid increase in amplitude, longitudinal dispersion ultimately becomes negligible relative to wave growth. To represent the observed quantities at large time, the transport equation is suitably weighted and averaged over the horizontal plane. Hyperbolic equations result, and the ascending and descending zones containing the fronts of the fingers are replaced by discontinuities. These averaged equations form an unclosed set, but closure is achieved by assuming a law for the mean wave-number based on similarity. It is found that the mean amplitude is fairly insensitive to changes in wave-number. Numerical solutions of the averaged equations give more detailed information about the growth behaviour, in excellent agreement with the similarity results and with the Hele-Shaw experiments.

scholarly journals Map-based methods for estimating glacier equilibrium-line altitudes

2003 ◽  
Vol 49 (166) ◽  
pp. 329-336 ◽  
Author(s):  
Katherine C. Leonard ◽  
Andrew G. Fountain
Keyword(s):  
Mass Balance ◽  
Sea Level ◽  
Equilibrium Line ◽  
Topographic Maps ◽  
Kinematic Waves ◽  
The Mean

AbstractWe examine the validity of two methods for estimating glacier equilibrium-line altitudes (ELAs) from topographic maps. The ELA determined by contour inflection (the kinematic ELA) and the mean elevation of the glacier correlate extremely well with the ELA determined from mass-balance data (observed ELA). However, the range in glacier elevations above sea level is much larger than the variation in ELA, making this correlation unhelpful. The data were normalized and a reasonable correlation (r2 = 0.59) was found between observed and kinematic ELA.The average of the normalized kinematic ELAs was consistently located down-glacier from the observed ELA, consistent with theory. The normalized mean elevation of the glacier exhibited no correlation and suggests that the toe–headwall altitude ratio is not a good approximation for the ELA. Kinematic waves had no effect on the position of the kinematic ELA. Therefore, topographic maps of glacier surfaces can be used to infer the position of the ELA and provide a method for estimating past ELAs from historic topographic maps.

Estimating contribution of high-frequency sea-level oscillations to the extreme sea levels in the Adriatic Sea

2021 ◽  
Author(s):  
Krešimir Ruić ◽  
Jadranka Šepić ◽  
Maja Karlović ◽  
Iva Međugorac
Keyword(s):  
Time Series ◽  
Sea Level ◽  
High Frequency ◽  
Adriatic Sea ◽  
Tide Gauge ◽  
Data Series ◽  
Sea Levels ◽  
Short Period ◽  
Extreme Sea Levels ◽  
Sea Level Oscillations

<p>Extreme sea levels are known to hit the Adriatic Sea and to occasionally cause floods that produce severe material damage. Whereas the contribution of longer-period (T > 2 h) sea-level oscillations to the phenomena has been well researched, the contribution of the shorter period (T < 2 h) oscillations is yet to be determined. With this aim, data of 1-min sampling resolution were collected for 20 tide gauges, 10 located at the Italian (north and west) and 10 at the Croatian (east) Adriatic coast. Analyses were done on time series of 3 to 15 years length, with the latest data coming from 2020, and with longer data series available for the Croatian coast. Sea level data were thoroughly checked, and spurious data were removed. </p><p>For each station, extreme sea levels were defined as events during which sea level surpasses its 99.9 percentile value. The contribution of short-period oscillations to extremes was then estimated from corresponding high-frequency (T < 2 h) series. Additionally, for four Croatian tide gauge stations (Rovinj, Bakar, Split, and Dubrovnik), for period of 1956-2004, extreme sea levels were also determined from the hourly sea level time series, with the contribution of short-period oscillations visually estimated from the original tide gauge charts.  </p><p>Spatial and temporal distribution of contribution of short-period sea-level oscillations to the extreme sea level in the Adriatic were estimated. It was shown that short-period sea-level oscillation can significantly contribute to the overall extremes and should be considered when estimating flooding levels. </p>

Analysis of the eastern Adriatic sea-level extremes

2021 ◽  
Author(s):  
Marija Pervan ◽  
Jadranka Šepić
Keyword(s):  
Sea Level ◽  
Adriatic Sea ◽  
Hot Spot ◽  
Storm Surges ◽  
Low Pressure ◽  
Long Period ◽  
Short Period ◽  
Sea Level Oscillations ◽  
Low Pass ◽  
Level Height

<p>The Adriatic Sea is known to be under a high flooding risk due to both storm surges and meteorological tsunamis, with the latter defined as short-period sea-level oscillations alike to tsunamis but generated by atmospheric processes. In June 2017, a tide-gauge station with a 1-min sampling resolution has been installed at Stari Grad (middle Adriatic Sea), the well-known meteotsunami hot-spot, which is, also, often hit by storm surges. </p><p>Three years of corresponding sea-level measurements were analyzed, and 10 strongest episodes of each of the following extreme types were extracted from the residual series: (1) positive long-period (T > 210 min) extremes; (2) negative long-period (T > 210 min) extremes; (3) short-period (T < 210) extremes. Long-period extremes were defined as situations during which sea level surpasses (is lower than) 99.7 (i.e. 2) percentile of sea level height, and short-period extremes as situations during which variance of short-period sea-level oscillations is higher than 99.4 percentile of total variance[J1]  of short-period series. A strong seasonal signal was detected for all extremes, with most of the positive long-period extremes appearing during November to February, and most of the negative long-period extremes during January to February. As for the short-period extremes, these appear evenly throughout the year, but strongest events seem to appear during May to July.</p><p>All events were associated to characteristic atmospheric situations, using both local measurements of the atmospheric variables, and ERA5 Reanalysis dataset. It was shown that positive low-pass extremes commonly appear during presence of low pressure over the Adriatic associated with strong SE winds (“sirocco”), and negative low-pass extremes are associated to the high atmospheric pressure over the area associated with either strong NE winds (“bora”), or no winds at all. On the other hand, high-pass sea level extremes are noticed during two distinct types of atmospheric situations corresponding to both “bad” (low pressure, strong SE wind) and “nice” (high pressure, no wind) weather.</p><p>It is particularly interesting that short-period extremes, of which strongest are meteotsunamis, are occasionally coincident with positive long-period extremes contributing with up to 50 percent to total sea level height – thus implying existence of a double danger phenomena (meteotsunami + storm surge). </p>

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