<Emphasis>H</Emphasis>ydrological variability of the <Emphasis>S</Emphasis>oummam watershed <Emphasis>(N</Emphasis>ortheastern <Emphasis>A</Emphasis>lgeria<Emphasis>)</Emphasis> and the possible links to climate fluctuations     

Imen?TurkiEmail author  Benoit?Laignel  Nicolas?Massei  Zeneddine?Nouaceur  Nadir?Benhamiche  Khodir?Madani 《Arabian Journal of Geosciences》2016,9(6):477

The long-term variability of rainfall in the Soummam watershed (NE Algeria) has been analysed over the past 108 years using continuous wavelet method in order to identify the interannual modes controlling the rainfall variability. Statistical analyses of rainfall timeseries have shown its distribution following five periods of time, limited by a series of discontinuities around 1935, 1950, 1970 and 1990. The continuous wavelet transform have demonstrated different low frequency modes: 2–4, 4–8, 8–16 and 16–32 years.The annual band is expanded during the full study period with some pics around 1905, 1920–1935 and 1960; it shows a negative long-term trend, in particular since the period 1970–1990 when a major change has been identified. Then, the relationships between climate patterns of North Atlantic Oscillation (NAO) and Southern Oscillation Index (SOI) and the hydrological variability in the frequency domain have been investigated; they have shown a mean explained variance of 40 and 24 %, respectively. Such variances are less obvious for the annual mode and increase for the interannual frequencies. The coherence suffer from high perturbations since the period 1970–1990 when the NAO (SOI) shifts from negative (positive) phases to positive (negative) ones. Such anomalies are responsible for significant changes of rainfall variability, emphasising the global warming effects.  相似文献   

Investigation of moment-rotation relation in different joint types and evaluation of their effects on segmental tunnel lining     

Abbas?Majdi  Hamed?Ajamzadeh  Siavash?NadimiEmail author 《Arabian Journal of Geosciences》2016,9(7):512

This paper presents the results of a numerical study that has been performed to investigate the different joint types that affect the moment-rotation relation and ultimate bending moment capacity of a joint. A 3D finite element method was adapted to establish elaborate numerical models of segments. To evaluate the possible differences in moment-rotation behavior between different joint types, 10 different joint types were simulated. Additionally, the effect of different joint types on behavior of a lining ring was investigated. The validity of the peridynamic simulation was tested by comparing results obtained in this paper against the results obtained in a study performed by Hordijk and Gijsbers. Observations of the results demonstrate that in a flat joint, the expanding of joint height increased the rotation stiffness of the joint in the linear branch, and accordingly, the ultimate bending moment of the joint increased. In the ring model, it was observed that the expanding of joint height led to the decreased of ring displacement and stress concentration in the joint. Whenever there were full surface contacts (contact two segment in total cross section) in the joints, the rotation stiffness of the joints in the linear branch became equal, and, as a result, the displacement in the ring model was the same in all joint types. In addition, it was observed that using a convex joint in the ring model increases the displacement of the ring. The ultimate bending moment of bolted joints was higher than that of joints without bolts, especially in the case of a negative moment.  相似文献   

Anomalous optical variations in the grossular garnet from the Eden Mills,Belvidere Mountain (Vermont,USA)     

Manzoor Ahmad Badar  Safdar Hussain  Shanawer Niaz  Saif ur Rehman 《Arabian Journal of Geosciences》2016,9(9):545

The optical anomalies, and surface and lamellar textures of a birefringent grossular garnet crystal from the Eden Mills, Belvidere Mountain, Vermont, USA, have been investigated by optical polarizing microscope, electron-probe micro-analyzer, back-scattered electron imaging, infrared spectroscopy, and single-crystal X-ray diffractometer from the standpoint of crystal growth. This grossular shows one-to-one correlation between natural surface features and its internal textures under crossed polarizers. Electron-probe micro-analyzer (EPMA) gave average chemical composition in (110) thin section, of bright lamella {Ca_2.97Mn_0.06}_∑3.03 [Al_1.59Fe_0.37Ti_0.01]_∑1.97(Si_3.00)_∑3.00 (Gros_79.5And_18.9Sps_1.6) and of dark host {Ca_2.99Mn _0.06}_∑3.05 [Al_1.73Fe_0.26 Ti_0.01]_∑2.00(Si_2.97OH_0.03)_∑3.00 (Gros_85.4And₁₃Sps_1.6). The correspondence of surface features and the internal textures with spiral or pyramidal growth mechanism suggest that the internal textures of the Eden Mills grossular are formed during growth process. The optical vibrational orientations and the growth steps inclination along [001] and \( \left[\overset{-}{1}10\right] \) directions predict monoclinic symmetry. With X-ray diffractometer (XRD) method, pseudocubic parameters are a = 11.839(2) Å, b = 11.855(1) Å, and c = 11.868(2) Å with interaxial angles α = 90.00(1)°, β = 89.99(1)°, and γ = 90.02(2)° that show orthorhombic symmetry of this crystal. Lamellar texture of Al³⁺-rich host with Fe³⁺-rich lamella infers cation ordering at octahedral site of the garnet structure. IR data favors the non-cubic orientation of [(OH) ₄] at tetrahedral position in this grossular structure.  相似文献   

Characterization of the Tertiary reservoir in Khabbaz Oil Field,Kirkuk area,Northern Iraq     

Dler?BabanEmail author  Hussein?Suad?Hussein 《Arabian Journal of Geosciences》2016,9(3):237

Tertiary reservoir represented by Jeribe, Anah, Azkand, and Azkand/Ibrahim formations has been studied from reservoir characterization point of view in Khabbaz Oil Field/Northern Iraq. Examined thin sections prepared from core rock samples which are selected from the wells Kz-8 and Kz-9 revealed the existence of different microfacies in which are varies types of porosity such as interparticle, intraparticle, moldic, vuggy, and fractures have been noticed. In addition to these different types of diagenetic features are represented mainly by cementation, dolomitization, recrystallization, and dissolution. The available log data for the wells Kz-11, Kz-14, and Kz-16 have been used in characterizing the reservoir properties of the studied formations. The detected lithologies from porosity logs showed domination of limestone, dolomitic limestone, and dolomites in addition to few thin beds of anhydrites in Jeribe Formation and thin beds of sand dominated lithologies in Azkand Formation. Clay content has been calculated from gamma ray log along the studied sections and appeared to be mostly of dispersed clay type as shown from density-neutron porosity crossplot of Thomas-Stieber. Correction from the effect of clay content has been done for all the measured sonic, density, and neutron porosities. The available porosity and permeability values which are measured from core tests in the well Kz-9 for the formations of Jeribe, Anah, and Azkand have been adapted to formalize the best equation for calculating permeability in the other studied wells which have no core test measurements but only log data (Kz-11, Kz-14, and Kz-16 wells). Depending on porosity, permeability, and shale content, the studied sections have been subdivided into seven reservoir units in the wells Kz-11 and Kz-16, and for eight reservoir units in the well Kz-14.  相似文献   

Sequence stratigraphic analysis of Eocene Rock Strata,Offshore Indus,southwest Pakistan     

Natasha Khan  Khaista Rehman  Sajjad Ahmad  Jamil Khokher  M. Iqbal Hajana  M. Hanif 《Marine Geophysical Researches》2016,37(3):207-228

In this study, seismic data from two wells (Pak G2-1 and Indus Marine-1C) and age diagnostic larger benthic foraminifera (LBF) within drill cuttings has been used for the first time to identify depositional sequences within the carbonates in the Offshore Indus Basin, Pakistan. The Offshore Indus is tectonically categorized as a passive continental margin where carbonates occur as shelf carbonates in the near offshore and on volcanic seamounts in deeper waters. Seismic data analysis has indicated the presence of minor faults and carbonate buildups above the igneous basement in the south. Patterns of the seismic reflections enabled definition of three seismic facies units identified as: Unit 1 basement, represented by chaotic, moderate amplitude reflection configuration; while parallel bedding and the drape of overlying strata is typical character of Unit 2, carbonate mound facies. The younger Miocene channels represent Unit 3. The diagnosis of Alveolina vredenburgi/cucumiformis biozone confirmed the Ilerdian (55–52 Ma) stage constituting a second order cycle of deposition for the Eocene carbonates (identified as Unit 2). The carbonate succession has been mainly attributed to an early highstand system tract (HST). The environmental conditions remained favorable leading to the development of keep-up carbonates similar to pinnacle buildups as a result of aggradation during late transgressive system tract and an early HST. The carbonate sequence in the south (Pak G2-1) is thicker and fossiliferous representing inner to middle shelf depths based on fauna compared to the Indus Marine-1C in the north, which is devoid of fossils. Three biozones (SBZ 5, SBZ 6 and SBZ 8) were identified based on the occurrence of LBF. The base of the SBZ 5 zone marks the larger foraminifera turnover and the Paleocene–Eocene (P–E) boundary. The LBF encountered in this study coincides with earlier findings for the P–E boundary. Our findings indicate that the entire Ilerdian stage ranges from 55.5 to 52 Ma that was the episode of warmer water conditions on the carbonate shelves leading to the diversification of K-strategist larger foraminifera. The larger foraminiferal assemblage encountered in this study confirms the findings. The possible indication of stratigraphic-combination traps, revealed as reflection terminations, make carbonate mounds in the south a potential exploration target.  相似文献   

RETRACTED ARTICLE: Elevated water level from strong wind along the Gulf of Thailand     

Cherdvong?SaengsupavanichEmail author 《Journal of Oceanography》2016,72(5):817-817

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Preface     

Makio?C.?HondaEmail author  Hiroaki?Saito  Eitarou?Oka  Toshi?Nagata 《Journal of Oceanography》2016,72(3):339-339

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Microstructure observations in the upper layer of the South China Sea   总被引：1，自引：1，他引：0  

Hui?Sun  Qingye?WangEmail author 《Journal of Oceanography》2016,72(5):777-786

A general pattern for turbulent mixing in the upper layer of the South China Sea (SCS) is presented based on TurboMAP measurements in April and May 2010. The turbulence level decreased significantly overall from north to south, and weakened from east to west in the northern SCS. The average dissipation rate north of 18°N reaches 1.69 × 10^?8 W/kg, approximately six times larger than that south of 18°N. The mean mixing efficiency in the SCS is 0.2, with a maximum of 0.31 near the Luzon Strait. At one repeatedly occupied station located in the central deep basin, the dissipation rate varies diurnally in the mixed layer and pycnocline due to diurnal heating and cooling by solar radiation and local barotropic tide, respectively.  相似文献   

AMSR-E sea surface temperature (SST) charts enhancement     

Anatoly?AleksaninEmail author  Vladimir?Kim  Vasily?Kachur 《Journal of Oceanography》2016,72(5):801-810

Microwave satellite images used for retrieving sea surface temperatures often have such distortions as noise and blurring of the thermal fronts. An image processing approach based on the Mumford-Shah model of optimal image approximation is considered for the solution to this problem. We divide images into flat areas and frontal zones, and then process these areas separately. Image fragmentation is based on automatic detection of the thermal front lines. SST enhancement in frontal zones is achieved by using image deconvolution methods. It has been shown that SST errors in high gradient areas reach 1–3 °C. The proposed approach can decrease this discrepancy.  相似文献   

Seasonal variations in the nitrogen isotopic composition of settling particles at station K2 in the western subarctic North Pacific     

Yoshihisa?MinoEmail author  Chiho?Sukigara  Makio?C.?Honda  Hajime?Kawakami  Kazuhiko?Matsumoto  Masahide?Wakita  Minoru?Kitamura  Tetsuichi?Fujiki  Kosei?Sasaoka  Osamu?Abe  Jan?Kaiser  Toshiro?Saino 《Journal of Oceanography》2016,72(6):819-836

Intensive observations using hydrographical cruises and moored sediment trap deployments during 2010 and 2012 at station K2 in the North Pacific Western Subarctic Gyre (WSG) revealed seasonal changes in δ ¹⁵N of both suspended and settling particles. Suspended particles (SUS) were collected from depths between the surface and 200 m; settling particles by drifting sediment traps (DST; 100–200 m) and moored sediment traps (MST; 200 and 500 m). All particles showed higher δ ¹⁵N values in winter and lower in summer, contrary to the expected by isotopic fractionation during phytoplankton nitrate consumption. We suggest that these observed isotopic patterns are due to ammonium consumption via light-controlled nitrification, which could induce variations in δ ¹⁵N(SUS) of 0.4–3.1 ‰ in the euphotic zone (EZ). The δ ¹⁵N(SUS) signature was reflected by δ ¹⁵N(DST) despite modifications during biogenic transformation from suspended particles in the EZ. δ ¹⁵N enrichment (average: 3.6 ‰) and the increase in C:N ratio (by 1.6) in settling particles suggests year-round contributions of metabolites from herbivorous zooplankton as well as TEPs produced by diatoms. Accordingly, seasonal δ ¹⁵N(DST) variations of 2.4–7.0 ‰ showed a significant correlation with primary productivity (PP) at K2. By applying the observed δ ¹⁵N(DST) vs. PP regression to δ ¹⁵N(MST) of 1.9–8.0 ‰, we constructed the first annual time-series of PP changes in the WSG. This new approach to estimate productivity can be a powerful tool for further understanding of the biological pump in the WSG, even though its validity needs to be examined carefully.  相似文献