Polarization and kinematic studies of SS 433 indicate a continuous and decelerating jet     

A. M. Stirling  R. E. Spencer  T. V. Cawthorne  Z. Paragi 《Monthly notices of the Royal Astronomical Society》2004,354(4):1239-1254

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The role of hydrologic regimes on dissolved organic carbon composition in an agricultural watershed     

Peter J. Hernes  Robert G.M. Spencer  Brian A. Pellerin  Brian A. Bergamaschi 《Geochimica et cosmochimica acta》2008,72(21):5266-5277

Willow Slough, a seasonally irrigated agricultural watershed in the Sacramento River valley, California, was sampled weekly in 2006 in order to investigate seasonal concentrations and compositions of dissolved organic carbon (DOC). Average DOC concentrations nearly doubled from winter baseflow (2.75 mg L⁻¹) to summer irrigation (5.14 mg L⁻¹), while a concomitant increase in carbon-normalized vanillyl phenols (0.11 mg 100 mg OC⁻¹ increasing to 0.31 mg 100 mg OC⁻¹, on average) indicates that this additional carbon is likely vascular plant-derived. A strong linear relationship between lignin concentration and total suspended sediments (r² = 0.79) demonstrates that agricultural management practices that mobilize sediments will likely have a direct and significant impact on DOC composition. The original source of vascular plant-derived DOC to Willow Slough appears to be the same throughout the year as evidenced by similar syringyl to vanillyl and cinnamyl to vanillyl ratios. However, differing diagenetic pathways during winter baseflow as compared to the rest of the year are evident in acid to aldehyde ratios of both vanillyl and syringyl phenols. The chromophoric dissolved organic matter (CDOM) absorption coefficient at 350 nm showed a strong correlation with lignin concentration (r² = 0.83). Other CDOM measurements related to aromaticity and molecular weight also showed correlations with carbon-normalized yields (e.g. specific UV absorbance at 254 nm (r² = 0.57) and spectral slope (r² = 0.54)). Our overall findings suggest that irrigated agricultural watersheds like Willow Slough can potentially have a significant impact on mainstem DOC concentration and composition when scaled to the entire watershed of the main tributary.  相似文献   

Geomorphic evidence for active tectonic deformation in the coastal part of Eastern Black Sea,Eastern Pontides,Turkey     

Mustafa Softa  Tahir Emre  Hasan Sözbilir  Joel Q. G. Spencer  Mehmet Turan 《Geodinamica Acta》2018,30(1):249-264

The Eastern Pontides (EP), which is the under transpressional deformation zone, is an active mountain belt that has been rising rapidly since the Cenozoic era because of the Arabian-Eurasian convergence. Morphometric studies have been performed to investigate the tectonic activity of this region and better understand the characteristics of the faults geomorphologically; the faults control the mountain fronts in the drainage basin of the EP. The results show the Hypsometric Curve (HC)-Hypsometric Integral (0.37-HI-0.67), Basin-Shaped Analysis (1.2-B_s-7), Valley-Floor-Width to Height-Ratio (0.4-V_f-1.2) and Asymmetry Factor (35-AF-81) applied to 46 drainage basins together with 9 tectonically controlled geomorphic indices (1.2-S_mf-1.5) and a Stream Length Gradient (30-S_L-120) indicate that the EP is tectonically active, and when the areas are evaluated according to S_mf and V_f analyses, the tectonic level is relatively high. According to our conceptual model for the uplifting of the EP, with respect to field studies and morphometric analysis, (i) the EP is the active deformation zone and has a “push-up” geometry in conjunction with the North Anatolian Fault; (ii) the EP is progressively uplifting at a rate of more than 0.5 mm/yr in along with the thrust faults of the Black Sea Fault (BSF) and Borjomi-Kazbegi Fault (BKF).  相似文献   

Performance of multi-model ensembles for the simulation of temperature variability over Ontario,Canada     

Aly Al Samouly  Chanh Nien Luong  Zhong Li  Spencer Smith  Brian Baetz  Maysara Ghaith 《Environmental Earth Sciences》2018,77(13):524

Climate ensembles utilize outputs from multiple climate models to estimate future climate patterns. These multi-model ensembles generally outperform individual climate models. In this paper, the performance of seven global climate model and regional climate model combinations were evaluated for Ontario, Canada. Two multi-model ensembles were developed and tested, one based on the mean of the seven combinations and the other based on the median of the same seven models. The performance of the multi-model ensembles were evaluated on 12 meteorological stations, as well as for the entire domain of Ontario, using three temperature variables (average surface temperature, maximum surface temperature, and minimum surface temperature). Climate data for developing and validating the multi-model ensembles were collected from three major sources: the North American Coordinated Regional Downscaling Experiment, the Digital Archive of Canadian Climatological Data, and the Climactic Research Unit’s TS v4.00 dataset. The results showed that the climate ensemble based on the mean generally outperformed the one based on the median, as well as each of the individual models. Future predictions under the Representative Concentration Pathway 4.5 (RCP4.5) scenario were generated using the multi-model ensemble based on the mean. This study provides credible and useful information for climate change mitigation and adaption in Ontario.  相似文献   

Secular change in earth processes: Preface     

Richard M.Palin  Christopher J.Spencer 《地学前缘(英文版)》2018,9(4):965-966

正1.Introduction Uniformitarianism is a traditional approach used in many areas of geoscience that assumes the geologic processes observed today operated similarly throughout all of Earth history(Hutton,1788;Windley,1993),with such an ideology commonly encapsulated by the maxim"the present is the key to the past".This concept is closely associated with the philosophical principle of Occam’s razor,as discussed by Gould(1987)in his critique of its usage in the natural sciences:"we should try to explain the past by causes now in  相似文献   

Thermal inertia and bolometric Bond albedo values for Mimas, Enceladus, Tethys, Dione, Rhea and Iapetus as derived from Cassini/CIRS measurements     

C.J.A. Howett  J.R. Spencer  M. Segura 《Icarus》2010,206(2):573-593

Spectra taken by Cassini’s Composite Infrared Spectrometer (CIRS) between 10 and 600 cm⁻¹ (17-1000 μm) of surface thermal emission of Mimas, Enceladus, Tethys, Dione, Rhea and Iapetus have been used to derive the thermal inertia and bolometric Bond albedo values. Only an upper limit for the bolometric Bond albedo of Iapetus’ dark leading side could be determined due to the insensitivity of the thermal model to albedo when albedos are very low. The thermal inertia in this region however is better constrained. The CIRS coverage of Enceladus is extensive enough that the latitudinal variation in these values from 60°S to 70°N has been determined in 10° wide bins. The bolometric Bond albedos determined here are consistent with literature values which show the surface of the saturnian icy moons to be covered in ice contaminated to varying degrees. The thermal inertia of the moons is shown to be in the range 9-, approximately 2-6 times lower than that of the Galilean satellites, implying a less well consolidated and more porous surface. The thermal inertias of Iapetus and Phoebe are somewhat higher, suggesting that the very low thermal inertias of satellites from Rhea inwards may be related to their probable coating of E-ring material. Latitudinal variations on the surface of Enceladus show that the bolometric Bond albedo and thermal inertia increase towards the active plume source at the south pole.  相似文献   

Deposition and deformation of fluvial–lacustrine sediments of the Upper Triassic–Lower Jurassic Whitmore Point Member,Moenave Formation,northern Arizona     

Lawrence H. Tanner  Spencer G. Lucas 《Sedimentary Geology》2010,223(1-2):180-191

The stratigraphic section of the Upper Triassic–Lower Jurassic Whitmore Point Member of the Moenave Formation at Potter Canyon, Arizona, comprises c. 26 m of gray to black shales and red mudstones interbedded with mainly sheet-like siltstones and sandstones. These strata represent deposition from suspension and sheetflow processes in shallow, perennial meromictic to ephemeral lakes, and on dry mudflats of the terminal floodout of the northward-flowing Moenave stream system. The lakes were small, as indicated by the lack of shoreline features and limited evidence for deltas. Changes in base level, likely forced by climate change, drove the variations between mudflat and perennial lacustrine conditions. Lenticular sandstones that occur across the outcrop face in the same stratigraphic interval in the lower part of the sequence represent the bedload fill of channels incised into a coarsening-upward lacustrine sequence following a fall in base level. These sandstones are distinctive for the common presence of over-steepened bedding, dewatering structures, and less commonly, folding. Deformation of these sandstones is interpreted as aseismic due to the lack of features typically associated with seismicity, such as fault-graded bedding, diapirs, brecciated fabrics and clastic dikes. Rapid deposition of the sands on a fluid-rich substrate produced a reverse density gradient that destabilized, and potentially fluidized the underlying, finer-grained sediments. This destabilization allowed synsedimentary subsidence of most of the channel sands, accompanied by longitudinal rotation and/or ductile deformation of the sand bodies.  相似文献   

Chandrayaan-1 X-ray Spectrometer (C1XS)—Instrument design and technical details     

C.J. Howe  D. Drummond  B. Maddison  R. Parker  J. Spencer  M. Grande  J. Huovelin  J. Gow  L. d’Uston 《Planetary and Space Science》2009,57(7):735-743

The UK-built Chandrayaan-1 X-ray Spectrometer (C1XS) is flying as an ESA instrument on India's Chandrayaan-1 mission to the Moon. The Chandrayaan-1 mission launched on the 22nd October 2008 and entered a 100 km polar lunar orbit on the 12th November 2008. C1XS builds on experience gained with the earlier D-CIXS instrument on SMART-1, but will be a technically much more capable instrument. Here we describe the instrument design.  相似文献   

Astrometric radio source catalogs     

K. J. Johnston  J. H. Spencer  G. H. Kaplan  W. J. Klepczynski  D. D. McCarthy 《Celestial Mechanics and Dynamical Astronomy》1980,22(2):143-151

A review of the accuracy of radio interferometric positions of extragalactic sources is given. A mean catalog of radio positions is presented. With the accuracy currently attainable, radio observations can contribute significantly to the determination of astronomical constants.  相似文献   

Travel-time inversion for simultaneous earthquake location and velocity structure determination in laterally varying media   总被引：13，自引：0，他引：13  

Carl Spencer  David Gubbins 《Geophysical Journal International》1980,63(1):95-116

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