Estimation of Tigris-Euphrates streamflow from regional paleoenvironmental proxy data     

Paul A. Kay  Douglas L. Johnson 《Climatic change》1981,3(3):251-263

A six thousand year history of streamflow in Mesopotamia is derived from a synthesis of regional paleoenvironmental proxy data. The proxy data are interpreted with consideration to the climatic signals represented in the records and to the temporal resolution of the records. A consideration of modern synoptic climatology suggests the spatial patterns of streamflow-generating precipitation in relation to atmospheric circulation. These patterns provide a framework for the interpretation of streamflow from the regional proxies. Given the nature of the data at hand, only a low frequency signal is reconstructed. Assessment of the role of small scale climatic fluctuations as a forcing function of population dynamics must await the availability of finer resolution environmental data.  相似文献   

How much water swept over the Lake Nyos dam during the 1986 gas disaster?     

S J Freeth  R L F Kay 《Bulletin of Volcanology》1991,53(2):147-150

The toxic aerosol of water and carbon dioxide which was released from Lake Nyos in August 1986 passed over the natural dam which confines the lake and devastated the valleys to the north. The gas release generated a wave of water which swept across the lake surface and damaged vegetation on the eastern and southern shore. However, the vegetation to either side of the spillway was undamaged and therefore, despite a recent suggestion to the contrary, any wave of water which passed over the dam could have been no more than a few centimetres high.  相似文献   

Artificial Recharge in Las Vegas Valley, Clark County, Nevada     

Terry Katzer  Kay Brothers 《Ground water》1989,27(1):50-56

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Numerical model studies on the generation and dissipation of the diurnal coastal-trapped waves over the Sakhalin shelf in the Sea of Okhotsk     

Jun Ono  Kay I. Ohshima 《Continental Shelf Research》2010

To clarify the generation and dissipation mechanisms of diurnal coastal-trapped waves (CTWs) over the Sakhalin shelf, a series of numerical experiments were conducted using a three-dimensional tidal model of the Okhotsk Sea with density stratification. The tidal model used has good reproduction owing to the careful fitting to the recent observations. The numerical experiments suggested that diurnal CTWs are primarily (~60%) generated by the conversion of tidal energy at the northern corner of the Sakhalin shelf, and further amplified by vorticity generation due to the water column oscillation from Sakhalin Bay and the influence of Kashevarov Bank. From the observations, it was found that diurnal CTWs are effectively dissipated by the strong spin-down due to bottom friction. The conventional turbulent closure model cannot reproduce the observed damping of diurnal CTWs, which raises a caution in modeling the tidal fields in high-latitude regions where diurnal CTWs exist. To resolve this underestimation of the damping, the vertical eddy viscosity was parameterized using its dependence on the observed major axis length of the diurnal tidal current ellipses, which improves the model reproduction on the damping of diurnal CTWs. The model also suggests that the spin-down effects due to friction associated with the sea-ice cover play an important role in the tidal current reduction in the region where diurnal CTWs exist, as the observations suggested.  相似文献   

An Early Pliocene lake and its surrounding vegetation in Zhejiang,East China   总被引：1，自引：0，他引：1  

Jin-Feng Li  Ya-Qin Hu  David Kay Ferguson  Yu-Fei Wang  Cheng-Sen Li 《Journal of Paleolimnology》2010,43(4):751-769

The palynomorph composition of an Early Pliocene assemblage from Du’ao Lake, Zhejiang Province, East China, including sporomorphs and algae, was analyzed to reconstruct the vegetation and climate around the lake, as well as the environmental conditions in the lake. A subtropical evergreen and deciduous broad-leaved mixed forest surrounding the lake is inferred from the pollen data. The composition of the green algae community indicates a clear, shallow (about 5–6 m deep), mesotrophic freshwater lake. The inferred pH was about 7.0–8.0 during the algae growing season. Applying the Coexistence Approach, the climatic conditions in Early Pliocene Du’ao were: (1) mean annual temperature ranged from 18.1 to 22.0°C, (2) difference in temperature between the coldest and warmest months ranged from 14.2 to 15.1°C, (3) mean temperature of the coldest month varied from 10.7 to 12.1°C, (4) mean temperature of the warmest month ranged from 23.5 to 25.4°C, (5) mean annual precipitation varied from about 994 to 1,255 mm, (6) minimum monthly precipitation ranged from about 9 to 11 mm, and (7) maximum monthly precipitation varied from approximately 219 to 245 mm. These values indicate that the Early Pliocene climate was subtropical.  相似文献   

The determination of minor and trace element associations in coal using a sequential microwave digestion procedure     

Kay L. Laban  Brian P. Atkin 《International Journal of Coal Geology》1999,41(4):817

A sequential extraction procedure, using acid digestion in a CEM MDS-81D® microwave system, is reported for the investigation of trace and minor element associations in coal in (1) mineral phases other than pyrite, (2) pyrite and (3) the organic matrix. The concentrations of sulphate, pyrite and organic sulphur can also be determined by this method. The extract solutions from each stage are rapidly analysed by ICP-AES. The association of major, minor and trace elements with mineral and organic phases is suggested for a suite of certified reference coal samples. In stage 1, a significant percentage of the total Ba, Co, Cr, Cu, Mn, Ni, Pb and Sr was extracted suggesting an association with silicate, carbonate, sulphate and phosphate minerals for these elements. In stage 2, a proportion of the Cu, Mn, Ni, Pb and Zn was dissolved implying the occurrence of these elements in pyrite. An association with the organic matrix is suggested for Cr and also for Ba and Sr in lower rank coals.  相似文献   

Seasonal Variations of Water Masses and Sea Level in the Southwestern Part of the Okhotsk Sea     

Motoyo Itoh  Kay I. Ohshima 《Journal of Oceanography》2000,56(6):643-654

A new grid data set for the southwestern part of the Okhotsk Sea was compiled by using all the available hydrographic data from the Japan Oceanographic Data Center, World Ocean Atlas 1994 and the other additional data sources with the resolution of about 10 km. We examine the seasonal variations of areas and volumes of Soya Warm Current Water (SWCW) and East Sakhalin Current Water (ESCW) and show that the exchanges of these water masses drastically occur in April and November. The peculiar variation of sea level in this region is also related with the water mass exchange. Sea level at the Hokkaido coast of the Okhotsk Sea reaches its minimum in April about two months later than in the case of ordinary mid-latitude ocean, and its maximum in December besides the summer peak. The winter peak of sea level in December is caused by the advent of fresh and cold ESCW which is accumulated at the subsurface layers (20–150 m) through the Ekman convergence by the prevailing northerly wind. Sea level minimum in April is caused by the release of the convergence and the recovery of dense SWCW that is saline and much colder than that in summer.  相似文献   

Local Extremes in the Lidar‐Derived Snow Cover of Alpine Glaciers          下载免费PDF全文

Kay Helfricht  Michael Lehning  Rudolf Sailer  Michael Kuhn 《Geografiska Annaler: Series A, Physical Geography》2015,97(4):721-736

Snow deposition and redistribution are major drivers of snow cover dynamics in mountainous terrain and contribute to the mass balance of alpine glaciers. The quantitative understanding of inhomogeneous snow distribution in mountains has recently benefited from advances in measuring technologies, such as airborne laser scanning (ALS). This contribution further advances the quantitative understanding of snow distribution by analysing the areas of maximum surface elevation changes in a mountain catchment with large and small glaciers. Using multi‐annual ALS observations, we found extreme surface elevation changes on rather thin borders along the glacier margins. While snow depth distribution patterns in less extreme terrain have presented high inter‐annual persistence, there is little persistence of those extreme glacier accumulations between winters. We therefore interpret the lack of persistence as the result of a predominance of gravity‐driven redistribution, which has an inherently higher random component because it does not occur with all conditions in all winters. In highly crevassed zones, the lidar‐derived surface elevation changes are caused by a complex interaction of ice flux divergence, the propagation of crevasses and snow accumulation. In general, the relative contribution of gravitational mass transport to glacier snow cover volume was found to decrease for glaciers larger than 5 km² in the investigated region. We therefore suggest that extreme accumulations caused by gravitational snow transport play a significant role in the glacier mass balance of small to medium‐size glaciers and that they may be successfully parameterized by simple mass redistribution algorithms, which have been presented in the literature.  相似文献   

Distribution, magnitude and characterization of the toxicity of Ukrainian estuarine sediments     

Burgess RM  Konovets IM  Kipnis LS  Lyashenko AV  Grintsov VA  Petrov AN  Terletskaya AV  Milyukin MV  Povolotskii MI  Demchenko VY  Bogoslovskaya TA  Topkin YV  Vorobyova TV  Portis LM  Ho KT 《Marine pollution bulletin》2011,62(11):2442-2462

During the Soviet era, Ukraine was an important industrial and agricultural region of the Soviet Union. This industrial and agricultural activity resulted in contamination of Ukraine’s estuaries with legacy anthropogenic pollutants. Investigations on the toxicological effects of this estuarine contamination have been limited. For this research, we measured the toxicity of contaminated sediments from four Ukrainian estuaries to several aquatic organisms over 3 years. Sediment chemical analyses and whole sediment toxicity identification evaluations (TIEs) were also performed to determine the classes of contaminants contributing to toxicity. Toxic sediments were observed in several of the Ukrainian estuaries and chemical analyses of the sediments demonstrated anthropogenic contaminants were widely distributed. Contaminants were also detected in macrobenthic organisms collected from the sediments. Several lines of evidence, including TIEs, indicated hydrophobic organic chemicals (HOCs) were contributing substantially to observed toxicity. This information can guide environmental managers to prioritize portions of the estuaries requiring remediation.  相似文献   

Can simulations reproduce the observed temperature–mass relation for clusters of galaxies?     

Peter A.Thomas  OrrarujeeMuanwong  Scott T.Kay  rew R.Liddle 《Monthly notices of the Royal Astronomical Society》2002,330(2):L48-L52

It has become increasingly apparent that traditional hydrodynamical simulations of galaxy clusters are unable to reproduce the observed properties of galaxy clusters, in particular overpredicting the mass corresponding to a given cluster temperature. Such overestimation may lead to systematic errors in results using galaxy clusters as cosmological probes, such as constraints on the density perturbation normalization σ ₈. In this paper we demonstrate that inclusion of additional gas physics, namely radiative cooling and a possible pre-heating of gas prior to cluster formation, is able to bring the temperature–mass relation in the innermost parts of clusters into good agreement with recent determinations by Allen, Schmidt & Fabian using Chandra data.  相似文献