Wyniki wyszukiwania - Biblioteka Nauki

1

Corretions to sea level anomalies data due to geocenter motion

100%

Kosek W. , Wnęk A. , Zbylut-Górska M.

Geomatics, Landmanagement and Landscape

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2015

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tom no. 2

33--44

EN

The objective of this paper is computation of the corrections to sea level anomaly data due to center of Earth mass variations. The geocenter motion model was computed from the center of mass coordinates data determined from observations of space geodetic techniques such as Satellite Laser Ranging (SLR), Global Navigation Satellite System (GNSS) and Doppler Orbitography and Radiopositionig Integrated on Satellite (DORIS). In order to compute the geocenter motion model the center of mass coordinates data were filtered using wavelet based semblance filtering which allows computing a common signal in two time series. Based on determined geocenter motion model a correction to sea level anomalies (SLA) data due to geocenter motion was determined. This kind of correction to sea level anomaly data is of the order of few millimetres and should be applied to altimetric measurements to refer them to the International Terrestrial Reference Frame (ITRF) Origin considered as the center of figure.

2

Studying the Sensitivity of Satellite Altimetry, Tide Gauge and GNSS Observations to Changes in Vertical Displacements

84%

Pająk K. , Kowalczyk K. , Kaminskis J. , Idzikowska M.

Geomatics and Environmental Engineering

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2021

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tom Vol. 15, no. 4

45--58

EN

Tide gauge observations provide sea level relative to the Earth’s crust, while satellite altimetry measures sea level variations relative to the centre of the Earth’s mass. Local vertical land motion can be a significant contribution to the measured sea level change. Satellite altimetry was traditionally used to study the open ocean, but this technology is now being used over inland seas too. The difference of both observations can be used to estimate vertical crustal movement velocities along the sea coast. In this paper, vertical crustal movement velocities were investigated at tide gauge sites along the Adriatic Sea coast by analyzing differences between Tide Gauge (TG) and Satellite Altimetry (SA) observations. Furthermore, the estimated vertical motion rates were compared with those from nearby GNSS measurements. The study determines the practical relationships between these vertical crustal movements and those determined from unrelated data acquired from the neighbouring GNSS stations. The results show general consistence with the present geodynamics in the Adriatic Sea coastal zone.

3

Foraminiferal Responses to Sea Level Changes Across the Mid-Carboniferous Boundary in Central Taurides (Turkey)

84%

Atakul-Özdemir A. , Altiner D. , Özkan-Altıner S.

Inżynieria Mineralna

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2024

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tom Vol. 1, no. 1

615--620

EN

The response of benthic foraminiferal assemblages to relative sea-level changes during the mid-Carboniferous succession of the Yarıcak Formation in the Central Taurides is assessed with respect to sedimentary cyclicity and sequence stratigraphy by quantitative analysis. The data derived from the relative abundances of foraminifera have critical significance in the understanding of cyclic patterns and sea level changes in carbonate deposits. Calcareous foraminiferal groups including archaediscids, eostaffellids, irregularly coiled bilocular forms, unilocular forms, paleotextularids, biseriamminids, endothyrids, and pseudoendothyrids have been counted and analysed in this study. The mid-Carboniferous boundary succession predominantly covering uniform lithology of carbonates alternated with sandstone layers involves shallowing upward cycles used for the revealing of sea-level fluctuations. The relative abundances of these foraminiferal groups reveal a striking response to cyclicity with the reductions in the abundances towards the upper part of the cycles. Conversely, the abundances of pseudoendothyrids and endothyrids do not exhibit any considerable variations within the studied interval.

4

Natural gamma radiation at the sea level around the Antarctic continent recorded south of the 62° parallel

84%

Długosz-Lisiecka M. , Krystek M. , Koper M. , Grala T. , Leniec-Koper H. , Barasiński M. , Talar M. , Kamiński I. , Kibart R. , Małecki W. , Kukliński P.

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2021

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nr 20

7-12

PL

W pracy przedstawiono wyniki dozymetrycznych pomiarów promieniowania, przeprowadzonych przez załogę jachtu Katharsis II, w trakcie 72-dniowego rejsu wokół Antarktydy. Podczas rejsu trwającego od stycznia do marca 2018 roku, za pomocą przenośnego radiometru Gamma Scout Online rejestrowano dawki promieniowania na poziomie morza w odstępach 10-minutowych. Po wstępnej analizie statystycznej uzyskano dane w postaci 2 200 rekordów, które wykorzystano do wnioskowania o rozkładzie promieniowania w rejonie Antarktyki. Średnia zmierzona moc dawki promieniowania wyniosła 0,091 μSvh-1 i wahała się od 0,052 do 0,193 μSvh-1. Wyniki te są powyżej średniej globalnej mocy dawki promieniowania na poziomie morza (0,031 μSvh-1) i często wyższe niż te zarejestrowane bezpośrednio na Antarktydzie. Jednak, generalnie zarejestrowane przez nas dawki promieniowania mieszczą się w dobrze rozpoznanym równoleżnikowym trendzie, w którym promieniowanie jest wyższe w kierunku biegunów. Związane jest to z cieńszą warstwą troposfery w rejonach biegunowych w porównaniu z niższymi, równikowymi szerokościami geograficznymi. Ogólnie pochodzenie tego promieniowania jest naturalne i związane z silniejszą penetracją troposfery przez promieniowanie kosmiczne oraz obecnością promieniowania wtórnego indukowanego w atmosferze. Obecność radionuklidów naziemnych w środowisku Antarktyki ma lokalny, wtórny wpływ na mierzone wartości promieniowania. Teoretycznie obliczony roczny ekwiwalent dawki dla ludzi, w różnych miejscach Antarktydy, może przekraczać limit 1 mSv, natomiast nasze wyniki (0,772 mSv rocznie) tego nie potwierdzają.

EN

This study presents the results of dosimetry radiation measurement performed in the Antarctic region at the surface of the sea which was conducted between January and March 2018. Over 2 200 records were collected using a portable Gamma Scout Online radiometer during a 72-day voyage circumnavigating the continent of Antarctica. The mean average of the measured radiation dose rate was 0.091 μSvh-1 and varied from 0.052 to 0.193 μSvh-1. These result are above global average dose rate of radiation at sea level (0.031 μSvh-1) and often higher than those recorded on the Antarctic continent. Yet generally our records fall within well recognized latitudinal trend of radiation being higher toward poles. This is results of troposphere begins at lower altitude in Antarctic in comparison to lower latitudes. The origin of this radiation is natural and results from the presence of higher cosmic rays and secondary radiation induced in the atmosphere. The presence of terrestrial radionuclides in the Antarctic environment has a local, secondary influence on the measured values of radiation. The theoretical calculated annual dose equivalent for humans present in Antarctica could often exceed the limit of 1 mSv as recorded for other Antarctic locations yet our results (0.772 mSv per year) do not confirm that.

5

Sea level prediction using climatic variables: a comparative study of SVM and hybrid wavelet SVM approaches

84%

Sithara S. , Pramada S. K. , Thampi S. G.

Acta Geophysica

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2020

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tom Vol. 68, no. 6

1779--1790

EN

Climate change is expected to adversely afect the coastal ecosystem in many ways. One of the major consequences of climate change in coastal areas is sea level rise. In order to manage this problem efciently, it is essential to obtain reasonably accurate estimates of future sea level. This study focuses essentially on the identifcation of climatic variables infuencing sea level and sea level prediction. Correlation analysis and wavelet coherence diagrams were used for identifying the infuencing variables, and support vector machine (SVM) and hybrid wavelet support vector machine (WSVM) techniques were used for sea level prediction. Sea surface temperature, sea surface salinity, and mean sea level pressure were observed to be the major local climatic variables infuencing sea level. Halosteric efect is found to have a major impact on the sea level. The variables identifed were subsequently used as predictors in both SVM and WSVM. WSVM employs discrete wavelet transform to decompose the variables before being input to the SVM model. The performance of both the models was compared using statistical measures such as root mean square error (RMSE), correlation coefcient (r), coefcient of determination (r 2 ), average squared error, Nash–Sutclife efciency, and percentage bias along with graphical indicators such as Taylor diagrams and regression error characteristic curves. Results indicate that the WSVM model predicted sea level with an RMSE of 0.029 m during the training and 0.040 m during the testing phases. The corresponding values for SVM are 0.043 m and 0.069 m, respectively. Also, the other statistical measures and graphical indicators suggest that WSVM technique outperforms the SVM approach in the prediction of sea level.

6

Recent Worldwide Tsunamis (2020-2023) - Comparisons Between Modeling and Measurements

84%

Partheniu R. , Tiganescu A. , Placinta A. O.

Inżynieria Mineralna

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2024

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tom Vol. 1, no. 1

681--689

EN

Few high magnitude earthquakes were generated worldwide in the last three and a half years, some of which triggered tsunami waves. We took into account all the events during the interval January 2020 - June 2023. There was a total of 15 earthquakes (5 in 2020, 5 in 2021, 2 in 2022, 2 in 2023) which lead to moderate and/or small tsunami waves (above 0.1 m), having magnitudes higher than 7, but also one earthquake with magnitude below 7 (6.8) which lead to very small tsunami waves generation. Not all the high magnitude earthquakes resulted in tsunami waves, depending on the depth, focal mechanism and / or other parameters (distance to shore, local conditions, etc.). From tsunami measurements point of view, we considered the most relevant ones and studied only the events that lead to measured waves higher than 0.5 m. The most significant ones are 5 events: 23rd of June 2020 (15:29 UTC), Near Coast of Oaxaca Mexico, M7.4 (maximum waves 0.68 m); 19th of October 2020 (20:55 UTC) South of Alaska M7.4 (maximum waves 0.76 m); 10th of February 2021 (13:20 UTC) Southeast of Loyalty Island, M7.7 (maximum waves 0.78 m); 4th of March 2021 (19:28 UTC) Kermadec Island region, M8.1 (maximum waves 0.56 m) and 19th of September 2022 (18:05 UTC), Coast of Michoacan Mexico M7.6 (maximum waves 0.79 m). We compared, in this paper, the values of sea level measurements with the results of the tsunami simulations, using the parameters of each earthquake (latitude, longitude, magnitude, depth, focal mechanism). The modeling simulations were accomplished using TRIDEC Cloud software, provided by the German Research Centre for Geosciences (GFZ), Potsdam, Germany. When comparing the values between the two types of data (measured vs. computed), the results show that some simulations overestimate the measured values, others underestimate it. More studies are necessary for a better numerical assessment of sea level, in order to be more precise and closer to the real measurements. Future work might include using two or three different modeling software, for the same earthquake parameters, and comparing the results.

7

Litostratygrafia dolnego syluru w odsłonięciu Bardo Stawy (południowa część Gór Świętokrzyskich) - związek ze zmianami poziomu morza i cyrkulacją oceaniczną

67%

Trela W. , Salwa S.

Przegląd Geologiczny

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2007

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tom Vol. 55, nr 11

971-978

EN

The lower Llandovery black radiolarian cherts and shales of the Bardo Formation are interpreted as transgressive to highstand deposits produced by the marine flooding initiated in latest Ordovician time (persculptus graptolite zone). This formation was divided into the Rembów radiolarian chert Member and Zbrza shale Member. The sedimentary record of the Rembów Member was folded due to the late Caledonian tectonic activity. The accumulation of the radiolarian cherts was influenced by an upwelling system generated by the SE trade winds, which were active along the southern margin of the southern Holy Cross Mountains.

8

A unique fossil record from neptunian sills: the world's most extreme example of stratigraphic condensation (Jurassic, western Sicily)

67%

Wendt J.

Acta Geologica Polonica

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2017

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tom Vol. 67, no. 2

163--199, [6]

EN

Neptunian sills at Rocca Busambra, a fragment of the Trapanese/Saccense Domain in western Sicily, host the most abundant ammonite and gastropod fauna which has ever been recorded from the Jurassic of the western Tethys. The fauna is dominated by parautochthonous organisms which were swept into the sills by gentle transport. Ammonites are characterized by perfect preservation and small size, a feature which is due to the predominance of microconchs but also of stunting. The most complete sill is 0.7 m thick and could be separated into 17 levels which range in age from the early Toarcian into the late Kimmeridgian, thus representing the most extreme case of palaeontologically and depositionally documented stratigraphic condensation in Earth history. The unique feature of the Rocca Busambra sills is due to the interaction of three processes: extreme stratigraphic condensation on the sea floor, weak tectonic fracturing of the host rock and repeated reopening on top of already existing sills. Contrasting percentages of gastropods in individual levels reflect sea-level oscillations which correspond to long known low- and highstands during the Jurassic of the western Tethys. Comparisons with other ammonite-bearing sill faunas reveal several similarities, but represent only short-timed phases of tectonic pulses and deposition.