Insights into the structure of the Wyville Thomson Ridge overflow current from a fine-scale numerical model     

Nataliya Stashchuk  Vasiliy Vlasenko  Toby J. Sherwin 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(10):1192-1205

One of the major pathways in the northern part of the Meridional Overturning Circulation (MOC) is that of the deep water in the Nordic Seas that runs through the Faroe-Shetland Channel (FSC) and Faroe Bank Channel (FBC), as well as crossing the Wyville Thomson Ridge (WTR), on its way into the Atlantic Ocean. The WTR overflow cascades down the southern side of the ridge via the narrow Ellett Gully to the Cirolana Deep (CD) which, at 1700 m, is the deepest hole in the extreme north of the Rockall Trough. The overflow accounts for nearly 1/10th of the total Faroe-Shetland Channel Bottom Water (FSCBW) discharged through the Faroese channels and is an important intermediate water mass in the Rockall Trough. Over a period of only seven days in April 2003 bottom water temperatures cooled dramatically, from 4.46 to 3.03 °C in the CD and from 3.93 to 2.54 °C in the Ymir Trough (YT). A numerical general circulation model (MITgcm) has been applied in order to reproduce the details of this dense water overflow event. Model results were consistent with the observed cooling and total water transport. It was found that the descending gravity current forms a pair of mesoscale eddies with cyclonic and anticyclonic vorticity at the exit to the CD. Analysis of mixing processes were obtained when a passive tracer was included in the model. It was found that downstream flow is characterized by an explosive detrainment regime in the CD. The model sensitivity runs revealed that the final depth to which the overflow descends depends on the initial upstream velocity of the overflow, as well as the buoyancy difference. It is argued that models of overflows need to have realistic representations of the density structure of the overflow, and sufficiently fine vertical resolution, for the subsequent fate of the overflow to be accurately represented.  相似文献   

The first magnetic chart     

Toby Clark FRAS  David Barraclough FRAS 《Astronomy& Geophysics》2001,42(1):1.23-1.25

Almost 300 years to the day since Edmond Halley's first magnetic chart, the RAS held a Discussion Meeting to commemorate this achievement and to consider Halley's work in navigation and geophysics. David Barraclough and Toby Clark report on the "300th anniversary of the first magnetic chart: Edmond Halley's work in geophysics and navigation".  相似文献   

Study of the velocity conditions in the earth's crust in the regions of the Bohemian massif and the carpathian system along international profiles VI and VII     

Břetislav Beránek  Reviewer V. Tobyáš 《Studia Geophysica et Geodaetica》1971,15(3-4):316-330

u¶rt;m n uu ¶rt;u m n u ma n¶rt;aa, nu m¶rt;u u ¶rt;uau. n nuu uu ¶rt;u m n ¶rt;a¶rt; nu NoNo VI, VII. u au u n m a (x, H), ¶rt;auu an¶rt;u ¶rt;u m ¶rt; m¶rt; nu, u mua m nuu (H), aamuu an¶rt;u m a mua ¶rt;¶rt; uu ¶rt;uua u a. u a ¶rt;u m (x, H) amm ¶rt;uuu (u) a m¶rt; nu. m¶rt; u, auuu aau, om aamuam muau an¶rt;u ¶rt;u m, uu , n m u m nu aamuu a nmu, am ma a¶rt;am aa uu ¶rt;u m. aa u a¶rt;u n nu NoNo VI u VII u umuu ¶rt;a. mua m nu (H) num m ¶rt;u amu aua u anam um, ¶rt;a amu ¶rt;aua u ¶rt;- nma (nu No VII). ma ¶rt; ¶rt; aua, maa numa nm m u numa nm ma¶rt;um, a unaa nuu umnmauu a¶rt;uu ¶rt;uau amu aua.  相似文献   

The constants of equivalent systems without feedback for computing the responses of electromagnetic seismographs with several galvanometers     

Vladimír Tobyáš  Reviewer J. Buben 《Studia Geophysica et Geodaetica》1976,20(2):133-148

Summary The amplitude and phase responses of electromagnetic seismographs with an arbitrary number of galvanometers, used to increase the dynamic range of the seismograph or to filter perturbing oscillations, are derived. The fundamental parameters of the system, i.e. the partial periods and the partial constants of damping of the seismometer and of the individual galvanometers, together with the coupling terms, are replaced by other constants. These enable the responses of each channel to be computed with the aid of a combination of elementary responses of the systems of the set with zero couplings between the galvanometers and a zero effect of the motion of the galvanometers on the motion of the seismometer. The elementary responses are defined by 2 types of substitute constants: equivalent constants, determined by the roots of the characteristic equation, or by the partial periods, and reduced damping constants. The possibilities of analysing a system with equivalent constants are demonstrated on the case of a seismograph with 2 galvanometers.  相似文献   

Correction of the level of magnification of the SVK vertical seismograph at the seismic station of průhonice (PRU)     

Vladimír Tobyáš  Reviewer J. Janský 《Studia Geophysica et Geodaetica》1981,25(1):99-103

Summary Drawing on the results of new measurements of the mechanical parameters of the SVK seismometer No. 5055, the level of magnification of the vertical seismograph used in the past, has been corrected. The amplitudes of the seismic waves from earthquakes in the period 1963–1978 have to be increased by 88% and the station correction for determining the magnitudes of earthquakes decreased by 0.274.  相似文献   

Spectra and polarization characteristics of geomagneticPc4 pulsations recorded at field station štrkovec     

Střeštík  Jaroslav  Tobyášová  Marta  Hvoždara  M. 《Studia Geophysica et Geodaetica》1983,27(3):248-256

ama nm u nmam nuau aamumuuaum nau muna Pc4 n ¶rt;a u mauu m, a¶rt; a m m anam ¶rt;u amu u¶rt;a umu. n¶rt;a auum nu¶rt;a u anum¶rt; nau u u nuau aamumu mu ¶rt; u m aum amumu, u au uu m¶rt; naam. mam auam mamau amu nau Pc3 u Pi2 n ¶rt;a u mau ¶rt; u u.  相似文献   

Dynamic properties and gravity meter sensitivity     

Vladimír Tobyáš  Karel Diviš  Reviewer Z. Šimon 《Studia Geophysica et Geodaetica》1983,27(1):1-8

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Seismic noise at some points of the gravimetric latitude base Hřensko — Dolní Dvořiště (CSSR)     

Vladimír Tobyáš  Karel Diviš  Reviewer Z. Šimon 《Studia Geophysica et Geodaetica》1975,19(1):89-95

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ОЦЕНКА ЭФФЕКТИВНОСТИ РЕГИСТРАЦИИ СЕЙСМИЧЕСКИХ СИГНАЛОВ     

Ю.Н Щтеменко  В.И Цибульский  Речензенm V. Tobyáš 《Studia Geophysica et Geodaetica》1974,18(3):238-247

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Calculation of constants of electromagnetic seismographs for recording velocity in case of non-negligible galvanometer reaction     

Vladimír Tobyáš 《Studia Geophysica et Geodaetica》1966,10(1):38-57

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