A quantitative assessment of changes in seasonal potential predictability for the twentieth century     

M. Azhar Ehsan  In-Sik Kang  Mansour Almazroui  M. Adnan Abid  Fred Kucharski 《Climate Dynamics》2013,41(9-10):2697-2709

Changes over the twentieth century in seasonal mean potential predictability (PP) of global precipitation, 200 hPa height and land surface temperature are examined by using 100-member ensemble. The ensemble simulations have been conducted by using an intermediate complexity atmospheric general circulation model of the International Center for Theoretical Physics, Italy. Using the Hadley Centre sea surface temperature (SST) dataset on a 1° grid, two 31 year periods of 1920–1950 and 1970–2000 are separated to distinguish the periods of low and high SST variability, respectively. The standard deviation values averaged for the (“Niño-3.4”; 5°S–5°N, 170°W–120°W) region are 0.71 and 1.15 °C, for the periods of low and high SST variability, respectively, with a percentage change of 62 % during December–January–February (DJF). The leading eigenvector and the associated principal component time series, also indicate that the amplitude of SST variations have positive trend since 1920s to recent years, particularly over the El Niño Southern Oscillation (ENSO) region. Our hypothesis states that the increase in SST variability has increased the PP for precipitation, 200 hPa height and land surface temperature during the DJF. The analysis of signal and noise shows that the signal-to-noise (S/N) ratio is much increased over most of the globe, particularly over the tropics and subtropics for DJF precipitation. This occurs because of a larger increase in the signal and at the same time a reduction in the noise, over most of the tropical areas. For 200 hPa height, the S/N ratio over the Pacific North American (PNA) region is increasing more than that for the other extratropical regions, because of a larger percentage increase in the signal and only a small increase in noise. It is also found that the increase in seasonal mean transient signal over the PNA region is 50 %, while increase in the noise is only 12 %, during the high SST variability period, which indicates that the increase in signal is more than the noise. For DJF land surface temperature, the perfect model notion is utilized to confirm the changes in PP during the low and high SST variability periods. The correlation between the perfect model and the other members clearly reveal that the seasonal mean PP changed. In particular, the PP for the 31 years period of 1970–2000 is higher than that for the 31 years period of 1920–1950. The land surface temperature PP is increased in northern and southern Africa, central Europe, southern South America, eastern United States and over Canada. The increase of the signal and hence the seasonal mean PP is coincides with an increase in tropical Pacific SST variability, particularly in the ENSO region.  相似文献   

The role of in situ stress in determining hydraulic connectivity in a fractured rock aquifer (Australia)     

Luke Mortimer  Adnan Aydin  Craig T. Simmons  Graham Heinson  Andrew J. Love 《Hydrogeology Journal》2011,19(7):1293-1312

Fracture network connectivity is a spatially variable property that is difficult to quantify from standard hydrogeological datasets. This critical property is related to the distributions of fracture density, orientation, dimensions, intersections, apertures and roughness. These features that determine the inherent connectivity of a fracture network can be modified by secondary processes including weathering, uplift and unloading and other mechanisms that lead to fracture deformation in response to in situ stress. This study focussed on a fractured rock aquifer in the Clare Valley, South Australia, and found that fracture network connectivity could be discriminated from several geological, geophysical and hydrogeological field datasets at various scales including single well and local- to regional-scale data. Representative hydromechanical models of the field site were not only consistent with field observations but also highlighted the strong influence of in situ stress in determining the distribution of fracture hydraulic apertures and the formation of hydraulic chokes that impede fluid flow. The results of this multi-disciplinary investigation support the notion that the hydraulic conductivity of a fracture network is limited to the least hydraulically conductive interconnected fractures, which imposes a physical limit on the bulk hydraulic conductivity of a fractured rock aquifer.  相似文献   

Re-appraisal of earthquake catalog in the Pamir―Hindu Kush region,emphasizing the early and modern instrumental earthquake events     

Rahman  Zahid  Rehman  Khaista  Ali  Wajid  Ali  Amir  Burton  Paul  Barkat  Adnan  Ali  Asghar  Qadri  S. M. Talha 《Journal of Seismology》2021,25(6):1461-1481

Journal of Seismology - The Pamir-Hindu Kush region is seismically the most dynamic and active zone that went through many devastating earthquakes. While much research is ongoing to produce seismic...  相似文献   

RETRACTED ARTICLE: Property market price response to flood-hazard     

Razali  Muhammad Najib  Zulkarnain  Siti Hafsah  Tarmidi  Zakri  Adi Maimun  Nurul Hana  Mohd. Adnan  Yasmin  Yuzir  Muhamad Ali 《Natural Hazards》2020,104(2):1955-1955

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Wheat Residue Management Options Affect Crop Productivity,Weed Growth,and Soil Properties in Direct‐Seeded Fine Aromatic Rice          下载免费PDF全文

Abdul Khaliq  Amar Matloob  Adnan Hussain  Saddam Hussain  Farhena Aslam  Shahid Ibni Zamir  Muhammad Umer Chattha 《洁净——土壤、空气、水》2015,43(8):1259-1265

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Landslide susceptibility mapping of vicinity of Yaka Landslide (Gelendost,Turkey) using conditional probability approach in GIS   总被引：4，自引：0，他引：4  

Adnan Ozdemir 《Environmental Geology》2009,57(7):1675-1686

On 19 February 2007, a landslide occurred on the Alaard?ç Slope, located 1.6 km south of the town of Yaka (Gelendost, Turkey.) Subsequently, the displaced materials transformed into a mud flow in E?lence Creek and continued 750 m downstream towards the town of Yaka. The mass poised for motion in the Yaka Landslide source area and its vicinity, which would be triggered to a kinetic state by trigger factors such as heavy or sustained rainfall and/or snowmelt, poise a danger in the form of loss of life and property to Yaka with its population of 3,000. This study was undertaken to construct a susceptibility mapping of the vicinity of the Yaka Landslide’s source area and to relate it to movement of the landslide mass with the goal of prevention or mitigation of loss of life and property. The landslide susceptibility map was formulated by designating the relationship of the effecting factors that cause landslides such as lithology, gradient, slope aspect, elevation, topographical moisture index, and stream power index to the landslide map, as determined by analysis of the terrain, through the implementation of the conditional probability method. It was determined that the surface area of the Goksogut formation, which has attained lithological characteristics of clayey limestone with a broken and separated base and where area landslides occur, possesses an elevation of 1,100–1,300 m, a slope gradient of 15 °–35 ° and a slope aspect between 0 °–67.5 ° and 157 °–247 °. Loss of life and property may be avoided by the construction of structures to check the debris mass in E?lence Creek, the cleaning of the canal which passes through Yaka, the broadening of the canal’s base area, elevating the protective edges along the canal and the establishment of a protective zone at least 10-m wide on each side of the canal to deter against damage from probable landslide occurrence and mud flow.  相似文献   

End bearing capacity comparison of screw pile with straight pipe pile under similar ground conditions     

Adnan Anwar Malik  Jiro Kuwano  Shinya Tachibana  Tadashi Maejima 《Acta Geotechnica》2017,12(2):415-428

In the present study, the end bearing capacity of screw and straight pipe pile under similar pile tip area and ground conditions were investigated. The effect of increasing overburden pressure was also considered in this research. Pile load tests on close-ended screw and straight pipe piles were conducted in the small scale. Dry Toyoura sand was used to develop the model ground. The sand was compacted at relative density of 70, 80 and 92 %. It was observed that in case of straight pipe pile, load settlement curve plunges downward without increase in load around settlement equals to 10 % of pile tip diameter, whereas in case of screw pile, the load settlement curve plunges around settlement equals to 15 % of pile tip diameter. Moreover, the screw piles having helix-to-shaft diameter ratio 2–4.1 showed 2–12 times higher end bearing capacity than straight pipe piles with similar pile shaft diameter. It was also observed from the test results that the end bearing capacity of single-helix screw pile was in average 16.25 % less than straight pipe pile with similar pile tip area and ground conditions irrespective of the effect of increasing overburden pressure.  相似文献   

Determining optimum number of geotechnical testing samples using Monte Carlo simulations     

Kerry Magner  Norbert Maerz  Ivan Guardiola  Adnan Aqeel 《Arabian Journal of Geosciences》2017,10(18):406

Knowing how many samples to test to adequately characterize soil and rock units is always challenging. A large number of tests decrease the uncertainty and increase the confidence in the resulting values of design parameters. Unfortunately, this large value also adds to project costs. This paper presents a method to determine the number of samples as a function of the coefficient of variation. If, as in the case of a reliability-based design, the resistance factors are a function of the coefficient of variation of the measurements, then lowering the coefficient of variation (COV) can result in lowering of the resistance factor resulting in a less conservative design. In this study, laboratory samples were isolated by specific unified soil classification system soil type and general site location. A distribution was fitted for each of the geotechnical parameters measured. For each scenario, groups of 2, 3, 4, 5, 10, 15, 20, 30, 50, and 100 random samples were generated by using Monte Carlo simulations from the fitted distributions. For each group, the variability was calculated in terms of the COV. In all cases, the COV decreased as the sample size increased. However, the rate of decrease for the COV was the greatest at a low number of samples; it becomes increasingly smaller at a higher number of samples.  相似文献   

Assessment and geospatial distribution mapping of fluoride concentrations in the groundwater of Al-Howban Basin,Taiz-Yemen     

Adnan Aqeel  Abdulmohsen Al-Amry  Omar Alharbi 《Arabian Journal of Geosciences》2017,10(14):312

Groundwater is one of the most important natural resources of drinking water on the earth planet. In rural areas of Yemen, groundwater is the main resource for drinking as well as for domestic purposes. According to the World Health Organization, one of the most important elements that has to be found in drinking water is fluorine (fluoride) but within the range of concentration of 0.5 up to 1.5 mg/l. Otherwise, any concentration of fluoride out of that range may cause serious diseases in human’s body such as fluorosis, kidney chronic disease, and/or nephrotoxicity. Taiz City, the third important and largest city in Yemen, has been suffering from dental fluorosis for a few decades. The main resource for drinking water in this city and adjacent areas is Al-Howban Basin (the study area) from where 33 groundwater samples were collected from 33 stations. These samples were preserved and then chemically analyzed according to the American Public Health Association Standards. The results reflected high levels of fluoride concentrations up to 3.6 mg/l in groundwater of many stations. GIS mapping was used to produce a geospatial distribution map of fluoride concentrations using ArcGIS-inverse distance weighted (IDW) tool. As a result, three zones of risks were identified in the study area: mild risk zone which covers the major part of the study area, moderate risk zone, and zone of no risk (optimum level zone). The last two zones occupy small portions of the study area. Consequently, dental and skeletal fluorosis, kidney, and/or nephrotoxic diseases are highly expected to be detected in the study area. Groundwater treatment measurements and health precautions are strongly recommended to be taken by local authorities in the near future.  相似文献   

A methodology for dynamic analysis of linear structure-foundation systems with local non-linearities     

Adnan Ibrahimbegovic  Edward L. Wilson 《地震工程与结构动力学》1990,19(8):1197-1208

An efficient computational technique is presented for the dynamic analysis of large linear structural systems with local non-linearities. The earthquake response evaluation for many practical structures belongs to this class of problems. The technique provides a rational approach to the earthquake-resistant design of structure-foundation systems with predetermined non-linearities occurring along the structure-foundation interface. Various possibilities for base isolation systems are naturally fitted within the proposed framework. In particular, we address uplifting of the structure as a natural base isolation concept. We use the dynamic substructuring technique and an efficient numerical algorithm which accommodates non-proportional damping as a consistent way to reduce significantly the computational effort, which is in sharp contrast to the vast majority of ad-hoc simplified models used for the same purpose. A numerical example which demonstrates the vibration isolation effect when the uplifting of the concrete gravity dam occurs is also presented.  相似文献