Propagation of Coronal Mass Ejections Observed During the Rising Phase of Solar Cycle 24     

M. Syed Ibrahim  P. K. Manoharan  A. Shanmugaraju 《Solar physics》2017,292(9):133

In this study, we investigate the interplanetary consequences and travel time details of 58 coronal mass ejections (CMEs) in the Sun–Earth distance. The CMEs considered are halo and partial halo events of width \({>}\,120\)°. These CMEs occurred during 2009?–?2013, in the ascending phase of the Solar Cycle 24. Moreover, they are Earth-directed events that originated close to the centre of the solar disk (within about \(\pm30\)° from the Sun’s centre) and propagated approximately along the Sun–Earth line. For each CME, the onset time and the initial speed have been estimated from the white-light images observed by the LASCO coronagraphs onboard the SOHO space mission. These CMEs cover an initial speed range of \({\sim}\,260\,\mbox{--}\,2700~\mbox{km}\,\mbox{s}^{-1}\). For these CMEs, the associated interplanetary shocks (IP shocks) and interplanetary CMEs (ICMEs) at the near-Earth environment have been identified from in-situ solar wind measurements available at the OMNI data base. Most of these events have been associated with moderate to intense IP shocks. However, these events have caused only weak to moderate geomagnetic storms in the Earth’s magnetosphere. The relationship of the travel time with the initial speed of the CME has been compared with the observations made in the previous Cycle 23, during 1996?–?2004. In the present study, for a given initial speed of the CME, the travel time and the speed at 1 AU suggest that the CME was most likely not much affected by the drag caused by the slow-speed dominated heliosphere. Additionally, the weak geomagnetic storms and moderate IP shocks associated with the current set of Earth-directed CMEs indicate magnetically weak CME events of Cycle 24. The magnetic energy that is available to propagate CME and cause geomagnetic storm could be significantly low.  相似文献   

Decrease in the clear air transmission at Helwan Observatory site     

J. S. Mikhail  B. B. Baghos  M. Y. Tawadrous  Y. E. Helali  H. Awad  KH. I. Khalil  M. El-Saftawe  M. Ibrahim 《Earth, Moon, and Planets》1995,70(1-3):143-149

Clear air atmospheric transparency of eight nights at Helwan Observatory site during autumn period of 1987 have been determined using the yellow filter GG5. The prevailing atmospheric transmission extends to 58%. A comparison with previous values obtained with the same filter and site during autumn period of 1963 shows a considerable decrease at the present years in the clear air transmission of the site of Helwan. This can be attributed to the aerosol pollution of the site caused mainly by the increase of the industrial centers at Helwan Zone. Clear air atmospheric transparency values at the beginning of winter season and at spring season are also given.  相似文献   

Interpretation of magnetic anomalies of dikes using correlation factors   总被引：1，自引：0，他引：1  

Ibrahim Kara  Mustafa Özdemir  F. Ahmet Yüksel 《Pure and Applied Geophysics》1996,147(4):777-788

The magnetic anomaly due to a buried dike consists of the sum of two easily separated elementary functions. These functions, which have simple symmetry, are called even and odd functions. The correlation factors (r _0,1 for the even andr _0,2 for the odd function) between least-squares residual anomalies from even and odd functions are computed. Correlation values are used to determine the depth to the top and the half-width of the dike. The method also includes the determination of the index parameter and the amplitude coefficient. The validity of the method is tested against a theoretical and a field example where the parameters of the latter were determined by other investigators in comparing the results.  相似文献   

Lunar electric fields,surface Potential and Associated Plasma Sheaths   总被引：1，自引：0，他引：1  

J. W. Freeman  M. Ibrahim 《Earth, Moon, and Planets》1975,14(1):103-114

This paper reviews the electric field environment of the Moon. Lunar surface electric potentials are reported as follows: Solar Wind - Dayside: ø_o + 10 to + 18 V Solar Wind - Terminator: ø_o ç ? 10 to ? 100 V Electron and ion densities in the plasma sheath adjacent to each surface potential regime are evaluated and the corresponding Debye length estimated. The electric fields are then approximated by the surface potential over the Debye length. The results are: Solar Wind - Dayside: E_o ? 10 V m^?1 outward Solar Wind - Terminator: E_o ç 1 to 10 V m^?1 inward These fields are all at least 3 orders of magnitude higher than the pervasive solar wind electric field; however they are confined to within a few tens of meters of the lunar surface.  相似文献   

Energy consumption,CO2 emissions and GDP in Nigeria     

Sulaiman Chindo  Abdulsamad Abdulrahim  Salisu Ibrahim Waziri  Wong M. Huong  Abdulfatah Abubakar Ahmad 《GeoJournal》2015,80(3):315-322

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Simulated watershed responses to land cover changes using the Regional Hydro‐Ecological Simulation System          下载免费PDF全文

Ibrahim Nourein Mohammed  David G. Tarboton 《水文研究》2014,28(15):4511-4528

In this work, we used the Regional Hydro‐Ecological Simulation System (RHESSys) model to examine runoff sensitivity to land cover changes in a mountain environment. Two independent experiments were evaluated where we conducted simulations with multiple vegetation cover changes that include conversion to grass, no vegetation cover and deciduous/coniferous cover scenarios. The model experiments were performed at two hillslopes within the Weber River near Oakley, Utah watershed (USGS gauge # 10128500). Daily precipitation, air temperature and wind speed data as well as spatial data that include a digital elevation model with 30 m grid resolution, soil texture map and vegetation and land use maps were processed to drive RHESSys simulations. Observed runoff data at the watershed outlet were used for calibration and verification. Our runoff sensitivity results suggest that during winter, reduced leaf area index (LAI) decreases canopy interception resulting in increased snow accumulations and hence snow available for runoff during the early spring melt season. Increased LAI during the spring melt season tends to delay the snow melting process. This delay in snow melting process is due to reduced radiation beneath high LAI surfaces relative to low LAI surfaces. The model results suggest that annual runoff yield after removing deciduous vegetation is on average about 7% higher than with deciduous vegetation cover, while annual runoff yield after removing coniferous vegetation is on average as about 2% higher than that produced with coniferous vegetation cover. These simulations thus help quantify the sensitivity of water yield to vegetation change. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Correlations of SPT,CPT and DPL Data for Sandy Soil in Tanzania     

Mwajuma Ibrahim Lingwanda  Stefan Larsson  Dalmas L. Nyaoro 《Geotechnical and Geological Engineering》2015,33(5):1221-1233

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Geology and geochemistry of the granitic rocks and associated dykes, East Gabal Nuqra, South Eastern Desert, Egypt     

Ibrahim H.Ibrahim  Mostafa E.Darwish 《中国地球化学学报》2012,31(4):376-389

A crescent-shape granitic stock and associated dykes is located to the East Gabal Nuqra at the extreme western part of Wadi Natash,South Eastern Desert,Egypt.The examined granites are classified as alkali-feldspar granites and mainly consist of quartz,potash feldspars,plagioclases,and aegirine-augite.Xenotime,zircon,apatite and allanite are accessories representing the source of Y,U,Th and REEs in these rocks.These granites are characterized by high K2O,Na2O and Zn contents and Rb/Sr ratio.Also,they are highly enriched in high field strength elements(HFSE),especially Zr(1529×10-6),Nb(100×10-6),Hf(91×10-6) and Y(624×10-6) and light rare-earth elements(LREE,141×10-6) concentrations and strongly depleted in Ca,Mg,Sr and Eu contents.These features suggest that they are similar to A-type granites(type-2).The rhyolite dykes and granites have similar geochemical characteristics whereas the chondrite-normalized REE patterns show a LREE enriched feature with strong negative Eu-anomaly,whereas the REE pattern of trachydacites show slightly fractionated pattern with no Eu-anomaly.It is suggested that the trachydacites were generated by small degree of partial-melting deep-seated basic source.Such liquid,when subjected to fractional crystallization involving separation of plagioclases as residue,generated the alkali-feldspar granites.And further fractional crystallization gave rise to the alkali rhyolites.The igneous rock suite originated from metaluminous to alkaline trachytic magma,and was developed in a within-plate tectonic environment.The extension caused by NW-SE right-lateral shear in area led to the emplacement of the alkali-feldspar granites.The later extrusion of the alkali rhyolite and trachydacite dykes was due to cauldron subsidence.  相似文献   

Opaque mineralogy and magnetic investigation of some basaltic occurrences, Sinai, Egypt     

Nadia Wassif  Ibrahim El-Hemaly  Emad Henery  Hatem Odah 《Arabian Journal of Geosciences》2012,5(4):769-779

Ore microscopic investigation of the Fe?CTi oxide minerals was carried out on samples from three Oligo-Miocene basaltic occurrences from Sinai, Egypt. These occurrences are Gebel Maghara (north Sinai), Rageibet Naama (central Sinai), and Wadi Matulla (west Sinai). The results and correlations of magnetic parameters such as NRM intensity and susceptibility, coercive force H _c, and the ratio M _r/M _s, H _c and Q value, the ratio M _r/M _s, saturation magnetization M _s, and K are discussed in light of opaque mineralogical studies. It has been found that the variations in the magnetic properties of the basaltic occurrences are strongly dependent on the crystallite size and nature and style of exsolution textures and fabrics. The latter are controlled by the cooling conditions, being most sensitive to the partial pressure of oxygen in the melt.  相似文献   

Effect of soil hydraulic properties model on slope stability analysis based on strength reduction method   总被引：2，自引：0，他引：2  

Muhammad Mukhlisin  Marlin Ramadhan Baidillah  Aniza Ibrahim  Mohd. Raihan Taha 《Journal of the Geological Society of India》2014,83(5):586-594

Soil hydraulic properties models which have been proposed were derived based on the empirical fitting curve such as Brooks-Corey model (BC) and Van Genuchten model (VG), or based on soil pore radius distribution such as Lognormal model (LN). Each model has different accuracy for predicting soil moisture distribution. In the analysis of rainfall-induced slope failure, the soil hydraulic properties model was needed to describe the physical phenomena of behavior characteristic of water in unsaturated soil. As moisture content has an effect on soil strength, it is vital to select the suitable soil hydraulic properties model for predicting Factor of Safety (FOS) especially in forecasting landslide hazard. In this study, a numerical model of seepage finite element analysis using BC, VG, and LN model were used and compared in order to analyze the soil moisture distribution, water movement phenomenon, and slope stability characteristic in unsaturated soil slope based on the strength reduction method (SRM). The results showed that the variations of the parameters predicting the moisture content of soil leads to differences of FOS in some cases. The parametric study showed that for the unsaturated soil condition, BC model has the greatest FOS value than the other model, while VG model has the lowest. On the other hand, the FOS of all models have the same result for the saturated condition. Other than that, it was found that the increasing of ESP value in the surface layer has significant effect in the sub-surface layer.  相似文献