Numerical modeling of the impact of hurricanes on ocean dynamics: sensitivity of the Gulf Stream response to storm’s track     

Ezer  Tal 《Ocean Dynamics》2019,69(9):1053-1066

Ocean Dynamics - The study is focused on the disruption that a storm can cause to ocean stratification and ocean currents in a region dominated by a western boundary current and meso-scale...  相似文献   

The vertical hydraulic conductivity of an aquitard at two spatial scales   总被引：4，自引：0，他引：4  

Hart DJ  Bradbury KR  Feinstein DT 《Ground water》2006,44(2):201-211

Aquitards protect underlying aquifers from contaminants and limit recharge to those aquifers. Understanding the mechanisms and quantity of ground water flow across aquitards to underlying aquifers is essential for ground water planning and assessment. We present results of laboratory testing for shale hydraulic conductivities, a methodology for determining the vertical hydraulic conductivity (K(v)) of aquitards at regional scales and demonstrate the importance of discrete flow pathways across aquitards. A regional shale aquitard in southeastern Wisconsin, the Maquoketa Formation, was studied to define the role that an aquitard plays in a regional ground water flow system. Calibration of a regional ground water flow model for southeastern Wisconsin using both predevelopment steady-state and transient targets suggested that the regional K(v) of the Maquoketa Formation is 1.8 x 10(-11) m/s. The core-scale measurements of the K(v) of the Maquoketa Formation range from 1.8 x 10(-14) to 4.1 x 10(-12) m/s. Flow through some additional pathways in the shale, potential fractures or open boreholes, can explain the apparent increase of the regional-scale K(v). Based on well logs, erosional windows or high-conductivity zones seem unlikely pathways. Fractures cutting through the entire thickness of the shale spaced 5 km apart with an aperture of 50 microns could provide enough flow across the aquitard to match that provided by an equivalent bulk K(v) of 1.8 x 10(-11) m/s. In a similar fashion, only 50 wells of 0.1 m radius open to aquifers above and below the shale and evenly spaced 10 km apart across southeastern Wisconsin can match the model K(v).  相似文献   

Imaging study of NGC 3372, the Carina nebula – I. UBVRIJHK photometry of Tr 14, Tr 15, Tr 16 and Car I     

Mauricio Tapia  Miguel Roth  Rubén A. Vázquez  Alejandro Feinstein 《Monthly notices of the Royal Astronomical Society》2003,339(1):44-62

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Spectral Ratio Estimates for Site Effects on the Horst–Graben System in West Turkey     

Nİhal Akyol  Tevfİk Özgür Kurtulmuş  Murat Çamyildiz  Talİp Güngör 《Pure and Applied Geophysics》2013,170(12):2107-2125

Recordings of micro- and moderate-size local earthquakes have been used to quantify site effects in the central-west Turkey which contains one of the world’s best examples of a rapid intra-continental extension with its high population and industrial potential. We analyzed 436 earthquakes with local magnitudes ranging between 2.0 and 5.6 using three component digital recordings from 32 stations. Site functions were obtained using two different spectral ratio approaches (horizontal to vertical spectral ratio, HVSR, and standard spectral ratio, SSR). HVSR estimates of transverse and radial S-waves were compared with one another. Epicentral distance, magnitude and back-azimuth dependencies of site functions were also evaluated. In general, HVSR values from transverse and radial S-waves are similar within a factor of 2. The back-azimuth dependencies of transverse S-wave HVSR results are more significant than distance and magnitude dependencies. On the other hand, averaging of transverse and radial S-wave HVSR results eliminates systematic back-azimuth dependencies caused by source radiation effects. Distributions of HVSR estimates along ~N–S linear array, which traversed main grabens in the region with a station spacing of 3–4 km, reflect subsurface geological complexities in the region. The sites located near the basin edges are characterized by broader HVSR curves. Broad HVSR peaks could be attributed to the complexity of wave propagation related to significant 2D/3D velocity variations at the sediment–bedrock interface near the basin edges. The results also show that, even if the site is located on a horst, the presence of weathered zones along the surface could cause moderate frequency dependent site effects. Comparison of HVSR and SSR estimates for the stations on the graben sites showed that SSR estimates give larger values at lower frequencies which could be attributed to lateral variations in regional velocity and attenuation values caused by basin geometry and edge effects.  相似文献   

On the dynamics of strait flows: an ocean model study of the Aleutian passages and the Bering Strait     

Tal Ezer  Lie-Yauw Oey 《Ocean Dynamics》2013,63(2-3):243-263

A high-resolution numerical ocean circulation model of the Bering Sea (BS) is used to study the natural variability of the BS straits. Three distinct categories of strait dynamics have been identified: (1) Shallow passages such as the Bering Strait and the Unimak Passage have northward, near barotropic flow with periodic pulses of larger transports; (2) wide passages such as Near Straits, Amukta Pass, and Buldir Pass have complex flow patterns driven by the passage of mesoscale eddies across the strait; and (3) deep passages such as Amchitka Pass and Kamchatka Strait have persistent deep return flows opposite in direction to major surface currents; the deep flows persist independent of the local wind. Empirical orthogonal function analyses reveal the spatial structure and the temporal variability of strait flows and demonstrate how mesoscale variations in the Aleutian passages influence the Bering Strait flow toward the Arctic Ocean. The study suggests a general relation between the barotropic and baroclinic Rossby radii of deformations in each strait, and the level of flow variability through the strait, independent of geographical location. The mesoscale variability in the BS seems to originate from two different sources: a remote origin from variability in the Alaskan Stream that enters the BS through the Aleutian passages and a local origin from the interaction of currents with the Bowers Ridge in the Aleutian Basin. Comparisons between the flow in the Aleutian passages and flow in other straits, such as the Yucatan Channel and the Faroe Bank Channel, suggest some universal topographically induced dynamics in strait flows.  相似文献   

Genetic characterization of gas shows in the east Mediterranean offshore of southwestern Israel     

S Feinstein  Z Aizenshtat  I Miloslavski  P Gerling  J Slager  J McQuilken 《Organic Geochemistry》2002,33(12)

Drilling in the eastern continental margin of the Levant Basin (southeastern Mediterranean), offshore southwestern Israel encountered light oil shows, numerous vertically stacked gas pockets and, more recently, commercial gas discoveries. Chemical and stable isotopic compositions obtained for 24 gas samples from Middle Jurassic to Pliocene reservoir rocks suggest that they represent a few genetic systems which are distributed vertically in the section in accordance with the stratigraphy. These groups include bacterial gas in the Pliocene, a mixture of bacterial and thermogenic gas in the Lower Cretaceous, and thermogenic gas in the Jurassic section. The bacterial gases in the Pliocene and the Lower Cretaceous appear not to be cogenetic, and likewise the thermogenic gas in the Lower Cretaceous and the Jurassic sections. Excluding one case, where the thermogenic gas appears to represent phase separation from a probably cogenetic light oil, the relationship of either the bacterial or other thermogenic gas samples to particular potential source rocks in the section or to light oil shows encountered in the Middle Jurassic section is at this stage inconclusive.  相似文献   

Interactive Effects of UV-B Radiation and Chemical Contamination on Physiological Parameters in the Lichen Ramalina lacera     

Jacob Garty  Tal Levin  Haya Lehr  Sharon Tomer  Ayala Hochman 《Journal of Atmospheric Chemistry》2004,49(1-3):267-289

To assess the impact of ultraviolet B (UV-B) radiation under laboratory conditions on lichens from different biomonitoring sites, thalli of the lichen Ramalina lacera were transplanted from a clean air site to nine different polluted sites in Israel. Our objective was to determine the probability of synergistic/antagonistic effects on physiological parameters by considering two stressors: chemical contamination and UV-B. Exposure to both airborne pollutants in the field and subsequent UV-B radiation in the laboratory which led to a severe disintegration of cell membranes, followed by electrolyte leakage, indicate the probability of a synergistic effect. The impairment of the potential quantum yield of electron transfer through photosystem II (PSII) of photosynthesis indicated by a significant decrease of the ratio F_v/F_m, further demonstrated the synergistic effect of both chemical contamination and UV-B radiation. Besides enlarged amounts of stress-ethylene in lichens at contaminated sites, the reduced levels of ethylene production upon UV-B radiation in the present study suggest the likelihood of an antagonistic effect of xenobiotic elements and UV-B radiation as a result of an impaired ethylene-producing system.  相似文献   

On the dynamics of low latitude,wide and shallow coastal system: numerical simulations of the Upper Gulf of Thailand   总被引：1，自引：1，他引：0  

Suriyan Saramul  Tal Ezer 《Ocean Dynamics》2014,64(4):557-571

A high-resolution (～1 km horizontal grid and 21 vertical layers) numerical model based on the Princeton Ocean Model (POM) has been used to study the 3D dynamics of the Upper Gulf of Thailand (UGOT). While influenced by tides and rivers like other estuarine systems, the UGOT is unique because it is wide (～100 km?×?100 km), it is shallow (average depth of only ～15 m), it is located in low latitudes (～12.5°N–13.5°N), and it is influenced by the seasonal monsoon. Sensitivity studies were thus conducted to evaluate the impact that surface heat fluxes, monsoonal winds, river runoffs, and the low latitude may have on the dynamics; the latter has been evaluated by modifying the Coriolis parameter and comparing simulations representing low and mid latitudes. The circulation in the UGOT changes seasonally from counter-clockwise during the northeast monsoon (dry season) to clockwise during the southwest monsoon (wet season). River discharges generate coastal jets, whereas river plumes tend to be more symmetric near the river mouth and remain closer to the coast in low latitudes, compared with mid-latitude simulations. River plumes are also dispersed along the coast in different directions during different stages of the monsoonal winds. The model results are compared favorably with a simple wind-driven analytical estuarine model. Comparisons between an El Niño year (1998) and a La Niña year (2000) suggest that water temperatures, warmer by as much as 2 °C in 1998 relative to 2000, are largely driven by decrease cloudiness during the El Niño year. The developed model of the UGOT could be used in the future to address various environmental problems affecting the region.  相似文献   

Editorial—International Workshop on Modeling the Ocean (IWMO) special issue part 2 in ocean dynamics     

Lie-Yauw Oey  Tal Ezer  Yasumasa Miyazawa  Chau-Ron Wu 《Ocean Dynamics》2010,60(5):1271-1272

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The transition region and coronal explorer   总被引：5，自引：0，他引：5  

Handy  B.N.  Acton  L.W.  Kankelborg  C.C.  Wolfson  C.J.  Akin  D.J.  Bruner  M.E.  Caravalho  R.  Catura  R.C.  Chevalier  R.  Duncan  D.W.  Edwards  C.G.  Feinstein  C.N.  Freeland  S.L.  Friedlaender  F.M.  Hoffmann  C.H.  Hurlburt  N.E.  Jurcevich  B.K.  Katz  N.L.  Kelly  G.A.  Lemen  J.R.  Levay  M.  Lindgren  R.W.  Mathur  D.P.  Meyer  S.B.  Morrison  S.J.  Morrison  M.D.  Nightingale  R.W.  Pope  T.P.  Rehse  R.A.  Schrijver  C.J.  Shine  R.A.  Shing  L.  Strong  K.T.  Tarbell  T.D.  Title  A.M.  Torgerson  D.D.  Golub  L.  Bookbinder  J.A.  Caldwell  D.  Cheimets  P.N.  Davis  W.N.  Deluca  E.E.  McMullen  R.A.  Warren  H.P.  Amato  D.  Fisher  R.  Maldonado  H.  Parkinson  C. 《Solar physics》1999,187(2):229-260

The Transition Region and Coronal Explorer (TRACE) satellite, launched 2 April 1998, is a NASA Small Explorer (SMEX) that images the solar photosphere, transition region and corona with unprecedented spatial resolution and temporal continuity. To provide continuous coverage of solar phenomena, TRACE is located in a sun-synchronous polar orbit. The ∼700 Mbytes of data which are collected daily are made available for unrestricted use within a few days of observation. The instrument features a 30-cm Cassegrain telescope with a field of view of 8.5×.5 arc min and a spatial resolution of 1 arc sec (0.5 arc sec pixels). TRACE contains multilayer optics and a lumogen-coated CCD detector to record three EUV wavelengths and several UV wavelengths. It observes plasmas at selected temperatures from 6000 K to 10 MK with a typical temporal resolution of less than 1 min.  相似文献