European climate in the late twenty-first century: regional simulations with two driving global models and two forcing scenarios   总被引：15，自引：2，他引：13  

J.?R?is?nenEmail author  U.?Hansson  A.?Ullerstig  R.?D?scher  L.?P.?Graham  C.?Jones  H.?E.?M.?Meier  P.?Samuelsson  U.?Willén 《Climate Dynamics》2004,22(1):13-31

A basic analysis is presented for a series of regional climate change simulations that were conducted by the Swedish Rossby Centre and contribute to the PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects) project. For each of the two driving global models HadAM3H and ECHAM4/OPYC3, a 30-year control run and two 30-year scenario runs (based on the SRES A2 and B2 emission scenarios) were made with the regional model. In this way, four realizations of climate change from 1961–1990 to 2071–2100 were obtained. The simulated changes are larger for the A2 than the B2 scenario (although with few qualitative differences) and in most cases in the ECHAM4/OPYC3-driven (RE) than in the HadAM3H-driven (RH) regional simulations. In all the scenario runs, the warming in northern Europe is largest in winter or late autumn. In central and southern Europe, the warming peaks in summer when it locally reaches 10 °C in the RE-A2 simulation and 6–7 °C in the RH-A2 and RE-B2 simulations. The four simulations agree on a general increase in precipitation in northern Europe especially in winter and on a general decrease in precipitation in southern and central Europe in summer, but the magnitude and the geographical patterns of the change differ markedly between RH and RE. This reflects very different changes in the atmospheric circulation during the winter half-year, which also lead to quite different simulated changes in windiness. All four simulations show a large increase in the lowest minimum temperatures in northern, central and eastern Europe, most likely due to reduced snow cover. Extreme daily precipitation increases even in most of those areas where the mean annual precipitation decreases.  相似文献   

Contact metamorphism and metasomatism at a dolerite-limestone contact in the Gebel Yelleq area, Northern Sinai, Egypt     

M. M. Abu El-Enen  M. Okrusch  T. M. Will 《Mineralogy and Petrology》2004,81(1-2):135-164

Summary At the northeastern flank of Gebel Yelleq, northern Sinai, pure limestones of Upper Cretaceous age were subjected to a thermal overprint, caused by a c. 80m thick Tertiary olivine dolerite sill. Metasomatic supply of Si, Al, Fe, Mg and Ti was greater to the c. 7m wide upper than to the c. 25m wide lower thermal aureole. The greater width of the lower aureole is possibly due to a longer duration of the thermal overprint at this contact. Mineral assemblages in both aureoles are (from the contact outward):(i) clinopyroxene + garnet ± wollastonite + calcite(ii) garnet ± wollastonite + calcite;(iii) wollastonite + calcite.In places, late stage xenoblasts of apophyllite and witherite overgrow these assemblages. Garnets are grandites to melanites with Grs_56–86Adr_14–42Sch_0–2Sps_0–0.2Prp₀ in the lower, and Grs_29–94Adr_5–64Sch_0–12Sps_0–0.2Prp_0–1.7 in the upper aureole. Close to the upper contact, clinopyroxene is virtually pure diopside with X _Mg = Mg/(Mg + Fe²⁺) = 0.97–1.0, whereas clinopyroxenes farther away from the upper contact and in the lower aureole have X _Mg-values of 0.49 and 0.53, respectively.The minimum temperatures reached during contact metamorphism in the upper and lower aureole are defined by the lower stability limit of wollastonite. The temperatures are inferred with a calculated T-X(CO₂) projection in the system CMASCH and are estimated at c. 290 °C and 380 °C for X(CO₂) values of 0.05 and 0.25, respectively. A pressure of roughly 100 bar is estimated for the lower dolerite-limestone contact. As indicated by one-dimensional thermal modelling, a maximum temperature of 695 °C was attained at this contact, assuming a magma temperature of 1150 °C. Further modelling results indicate (i) wollastonite, which occurs first 13 m away from the lower contact, formed at a maximum temperature of c. 575 °C, (ii) there, wollastonite formation lasted for approximately 170 years and, (iii) at the outer rim of the lower aureole, the maximum temperature reached was 480 °C, and temperatures sufficient for wollastonite formation lasted for about 140 years.  相似文献   

The 2dF Galaxy Redshift Survey: spectra and redshifts     

Matthew Colless  Gavin Dalton  Steve Maddox  Will Sutherland  Peder Norberg  Shaun Cole  Joss Bland-Hawthorn  Terry Bridges  Russell Cannon  Chris Collins  Warrick Couch  Nicholas Cross  Kathryn Deeley  Roberto De Propris  Simon P. Driver  George Efstathiou  Richard S. Ellis  Carlos S. Frenk  Karl Glazebrook  Carole Jackson  Ofer Lahav  Ian Lewis  Stuart Lumsden  Darren Madgwick  John A. Peacock  Bruce A. Peterson  Ian Price  Mark Seaborne  Keith Taylor 《Monthly notices of the Royal Astronomical Society》2001,328(4):1039-1063

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Development of modified flyash as a permeable reactive barrier medium for a former manufactured gas plant site, Northern Ireland     

R. Doherty  D.H. Phillips  K.L. McGeough  K.P. Walsh  R.M. Kalin 《Environmental Geology》2006,50(1):37-46

A sequential biological permeable reactive barrier (PRB) was determined to be the best option for remediating groundwater that has become contaminated with a wide range of organic contaminants (i.e., benzene, toluene, ethylbenzene, xylene and polyaromatic hydrocarbons), heavy metals (i.e., lead and arsenic), and cyanide at a former manufactured gas plant after 150 years of operation in Portadown, Northern Ireland. The objective of this study was to develop a modified flyash that could be used in the initial cell within a sequential biological PRB to filter complex contaminated groundwater containing ammonium. Flyash modified with lime (CaOH) and alum was subjected to a series of batch tests which investigated the modified cation exchange capacity (CEC) and rate of removal of anions and cations from the solution. These tests showed that a high flyash composition medium (80%) could remove 8.65 mol of ammonium contaminant for every kilogram of medium. The modified CEC procedure ruled out the possibility of cation exchange as the major removal mechanism. The medium could also adsorb anions as well as cations (i.e., Pb and Cr), but not with the same capacity. The initial mechanism for Pb and Cr removal is probably precipitation. This is followed by sorption, which is possibly the only mechanism for the removal of dichromate anions. Scanning electron microscopic analysis revealed very small (<1 μm) cubic highly crystalline precipitates on the flyash, although this new crystalline zeolite growth did not occur rapidly enough to enable productive zeolite formation. Surface area measurements showed that biofilm growth on the medium could be a major factor in the comparative reduction of surface area between real and synthetic contaminant groundwaters. The modified flyash was found to be a highly sorptive granular material that did not inhibit microbiological activity, however, leaching tests revealed that the medium would fail as a long-term barrier material.  相似文献   

PSDF: Particle Stream Data Format for N-body simulations     

Will M. Farr  Jeff AmesPiet Hut  Junichiro MakinoSteve McMillan  Takayuki MuranushiKoichi Nakamura  Keigo NitadoriSimon Portegies Zwart 《New Astronomy》2012,17(5):520-523

We present a data format for the output of general N-body simulations, allowing the presence of individual time steps. By specifying a standard, different N-body integrators and different visualization and analysis programs can all share the simulation data, independent of the type of programs used to produce the data. Our Particle Stream Data Format, PSDF, is specified in YAML, based on the same approach as XML but with a simpler syntax. Together with a specification of PSDF, we provide background and motivation, as well as specific examples in a variety of computer languages. We also offer a web site from which these examples can be retrieved, in order to make it easy to augment existing codes in order to give them the option to produce PSDF output.  相似文献   

Climate Change on Newfoundland and Labrador Shelves: Results From a Regional Downscaled Ocean and Sea-Ice Model Under an A1B Forcing Scenario 2011–2069     

Guoqi Han  Zhimin Ma  Zhenxia Long  Will Perrie  Joël Chassé 《大气与海洋》2019,57(1):3-17

Climate change may affect ocean and ice conditions in coastal oceans and thus have significant impacts on coastal infrastructure, marine navigation, and marine ecosystems. In this study a three-dimensional ice–ocean model is developed to examine likely changes of ocean and ice conditions over the Newfoundland and Labrador Shelves in response to climate change. The model is configured with a horizontal grid of approximately 7?km and a vertical grid of 46 levels and is run from 1979 to 2069. The projection period is 2011 to 2069 under a median emission scenario A1B used by the Intergovernmental Panel on Climate Change. For the projection period, the surface atmospheric forcing fields used are from the Canadian Regional Climate Model over the North Atlantic. The open boundary conditions come from the Canadian Global Climate Model, Version 3 (CGCM3), adjusted for the 1981–2010 mean of the Simple Ocean Data Assimilation model output. The simulated fields over the 1981–2010 period have patterns consistent with observations. Over the Newfoundland and Labrador Shelves during the projection period, the model shows general trends of warming, freshening, and decreasing ice. From 2011 to 2069, the model projects that under A1B sea surface temperature will increase by 1.4°C; bottom temperature will increase by 1.6°C; sea surface salinity will decrease by 0.7; bottom salinity will decrease by 0.3; and sea-ice extent will decrease by 70%. The sea level will rise by 0.11?m at the St. John's tide-gauge station because of oceanographic change, and the freshwater transport of the Labrador Current will double as a result of freshening. The regional ice–ocean model reproduces more realistic present climate conditions and projects considerably different future climate conditions than CGCM3.  相似文献   

Effect of particle size distribution on the bio-cementation of coarse aggregates   总被引：1，自引：0，他引：1  

Aamir Mahawish  Abdelmalek Bouazza  Will P. Gates 《Acta Geotechnica》2018,13(4):1019-1025

The effect of grain size distribution on the unconfined compressive strength (UCS) of bio-cemented granular columns is examined. Fine and coarse aggregates were mixed in various percentages to obtain five different grain size distributions. A four-phase percolation strategy was adopted where a bacterial suspension and a cementation solution (urea and calcium chloride) were percolated sequentially. The results show that a gap-graded particle size distribution can improve the UCS of bio-cemented coarser granular materials. A maximum UCS of approximately 575 kPa was achieved with a particle size distribution containing 75% coarse aggregate and 25% fine aggregate. Furthermore, the minimum UCS obtained has applications where mitigation of excessive bulging of stone/sand columns, and possible slumping that might occur during their installation, is needed. The finding also implies that the amount of biochemical treatments can be reduced by adding fine aggregate to coarse aggregate resulting in effective bio-cementation within the pore matrix of the coarse aggregate column as it could substantially reduce the cost associated with bio-cementation process. Scanning electron microscopy results confirm that adding fine aggregate to coarse aggregate provides more bridging contacts (connected by calcium carbonate precipitation) between coarse aggregate particles, and hence, the maximum UCS achieved was not necessarily associated with the maximum calcium carbonate precipitation.  相似文献   

Impact of peatland drainage and restoration on esker groundwater resources: modeling future scenarios for management   总被引：1，自引：0，他引：1  

Pekka M. Rossi  Pertti Ala-aho  John Doherty  Bjørn Kløve 《Hydrogeology Journal》2014,22(5):1131-1145

Esker aquifers are common groundwater bodies in Europe. Management of these aquifers should take account of the sustainability of groundwater-dependent ecosystems and land use in an integrated way. An unconfined esker aquifer in northern Finland was modelled with MODFLOW to determine how groundwater resources are impacted by the surrounding peatland drainage scheme and to simulate scenarios for possible drainage restoration. The impacts of groundwater abstraction and climate change were also simulated. A calibration-constrained Monte Carlo method was used to provide information on the uncertainties associated with model predictions. The results suggest that peatland drainage in the vicinity of eskers can have a significant role in lowering the water table, even though climate variability may mask these impacts. Drainage restoration by filling the ditches might have positive impacts on the aquifer water levels. Comparison of water-table changes caused by peatland drainage with the changes brought by water abstraction and climate variability helped to quantify impacts of different land-use scenarios and facilitated discussion with the local stakeholders. Based on this study, more attention should be devoted to peatland drainage schemes in integrated groundwater management of esker aquifers.  相似文献   

The Confrontation between General Relativity and Experiment     

Clifford M. Will 《Astrophysics and Space Science》2003,283(4):543-552

We review the experimental evidence for Einstein's general relativity. Tests of the Einstein Equivalence Principle support the postulates of curved spacetime and bound variations of fundamental constants in space and time, while solar-system experiments strongly confirm weak-field general relativity. The Binary Pulsar provides tests of gravitational-wave damping and of strong-field general relativity. Future experiments, such as the Gravity Probe B Gyroscope Experiment, a satellite test of the Equivalence principle, and tests of gravity at short distance to look for extra spatial dimensions could further constrain alternatives to general relativity. Laser interferometric gravitational-wave observatories on Earth and in space may provide new tests of scalar-tensor gravity and graviton-mass theories via the properties of gravitational waves. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

The 2dF Galaxy Redshift Survey: power-spectrum analysis of the final data set and cosmological implications     

Shaun Cole  Will J. Percival  John A. Peacock  Peder Norberg  Carlton M. Baugh  Carlos S. Frenk  Ivan Baldry  Joss Bland-Hawthorn  Terry Bridges  Russell Cannon  Matthew Colless  Chris Collins  Warrick Couch  Nicholas J. G. Cross  Gavin Dalton  Vincent R. Eke  Roberto De Propris  Simon P. Driver  George Efstathiou  Richard S. Ellis  Karl Glazebrook  Carole Jackson  Adrian Jenkins  Ofer Lahav  Ian Lewis  Stuart Lumsden  Steve Maddox  Darren Madgwick  Bruce A. Peterson  Will Sutherland  Keith Taylor 《Monthly notices of the Royal Astronomical Society》2005,362(2):505-534

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