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11.
Ramzi?TouchanEmail author Gary?Funkhouser Malcolm?K.?Hughes Nesat?Erkan 《Climatic change》2005,72(3):339-353
May–July Standardized Precipitation Index (SPI) for the land area of most of Turkey and some adjoining regions are reconstructed
from tree rings for the period 1251–1998. The reconstruction was developed from principal components analysis (PCA) of four
Juniperus excelsa chronologies from southwestern and south-central Turkey and is based on reliable and replicable statistical relationships
between climate and tree ring growth. The SPI reconstruction shows climate variability on both interannual and interdecadal
time scales. The longest period of consecutive drought years in the reconstruction (SPI threshold ≤−1) is 2 yr. These occur
in 1607–1608, 1675–1676, and 1907–1908. There are five wet events (SPI threshold ≥+1) of two consecutive years each (1330–1331,
1428–1429, 1503–1504, 1629–1630, and 1913–1914). A 5-yr moving average of the reconstructed SPI shows that two sustained drought
periods occurred from the mid to late 1300s and the early to mid 1900s. Both episodes are characterized by low variability. 相似文献
12.
Geotectonics - Tunisia had been the place of various tectonic episodes which have drawn the actual structural map of the country. The Neogene period was the most active period in which the... 相似文献
13.
May-June precipitation reconstruction of southwestern Anatolia, Turkey during the last 900 years from tree rings 总被引：1，自引：0，他引：1
A May-June precipitation reconstruction (AD 1097-2000) has been developed for southwestern Anatolia in Turkey, the longest reported to date in this region. The reconstruction was derived from a regional Juniperus excelsa chronology that was built from material sampled at four sites in the Antalya and Mersin Districts. The regional tree-ring chronology accounts for 51% of the variance of instrumentally observed May-June precipitation. The years AD 1518 to 1587 are the most humid period in the reconstruction, coinciding with a major shift in European climate. The driest 70-year period in the reconstruction is AD 1195 to 1264. The period AD 1591-1660 represents the third driest and was characterized by instability climatically, politically, and socially in Anatolia. 相似文献
14.
Yahia E.-A. Mohamedzein Mohammed Y. Al-Aghbari Ramzi A. Taha 《Geotechnical and Geological Engineering》2006,24(6):1767-1780
This paper presents experimental results on the use of incinerator ash in stabilizing desert sands for possible use in geotechnical
engineering applications. The incinerator ash was added in percentages of 2, 4, 8, 10 and 12%, by dry weight of sand. Laboratory
tests such as compaction, unconfined compression, shear box and hydraulic conductivity were performed to measure the engineering
characteristics of the stabilized material. The results showed substantial improvements in unconfined compressive strength
and shear strength parameters (c and φ). Thus, incinerator ash can be used to improve the shear strength characteristics of desert sands. The permeability of the
sand–incinerator ash mixture was relatively low. 相似文献
15.
International Journal of Earth Sciences - New field observations carried out in northeastern Tunisia (Kechabta Neogene basin) allowed us to clarify and pinpoint the chronology of the folding phases... 相似文献
16.
Niklas Höhne Christopher Taylor Ramzi Elias Michel Den Elzen Keywan Riahi Claudine Chen 《Climate Policy》2013,13(3):356-377
This article provides further detail on expected global GHG emission levels in 2020, based on the Emissions Gap Report (United Nations Environment Programme, December 2010), assuming the emission reduction proposals in the Copenhagen Accord and Cancun Agreements are met. Large differences are found in the results of individual groups owing to uncertainties in current and projected emission estimates and in the interpretation of the reduction proposals. Regardless of these uncertainties, the pledges for 2020 are expected to deliver emission levels above those that are consistent with a 2°C limit. This emissions gap could be narrowed through implementing the more stringent conditional pledges, minimizing the use of ‘lenient’ credits from forests and surplus emission units, avoiding double-counting of offsets and implementing measures beyond current pledges. Conversely, emission reduction gains from countries moving from their low to high ambition pledges could be more than offset by the use of ‘lenient’ land use, land-use change and forestry (LULUCF) credits and surplus emissions units, if these were used to the maximum. Laying the groundwork for faster emission reduction rates after 2020 appears to be crucial in any case. 相似文献
17.
Analysis of the traveltime sensitivity kernels for an acoustic transversely isotropic medium with a vertical axis of symmetry 
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下载免费PDF全文 In anisotropic media, several parameters govern the propagation of the compressional waves. To correctly invert surface recorded seismic data in anisotropic media, a multi‐parameter inversion is required. However, a tradeoff between parameters exists because several models can explain the same dataset. To understand these tradeoffs, diffraction/reflection and transmission‐type sensitivity‐kernels analyses are carried out. Such analyses can help us to choose the appropriate parameterization for inversion. In tomography, the sensitivity kernels represent the effect of a parameter along the wave path between a source and a receiver. At a given illumination angle, similarities between sensitivity kernels highlight the tradeoff between the parameters. To discuss the parameterization choice in the context of finite‐frequency tomography, we compute the sensitivity kernels of the instantaneous traveltimes derived from the seismic data traces. We consider the transmission case with no encounter of an interface between a source and a receiver; with surface seismic data, this corresponds to a diving wave path. We also consider the diffraction/reflection case when the wave path is formed by two parts: one from the source to a sub‐surface point and the other from the sub‐surface point to the receiver. We illustrate the different parameter sensitivities for an acoustic transversely isotropic medium with a vertical axis of symmetry. The sensitivity kernels depend on the parameterization choice. By comparing different parameterizations, we explain why the parameterization with the normal moveout velocity, the anellipitic parameter η, and the δ parameter is attractive when we invert diving and reflected events recorded in an active surface seismic experiment. 相似文献