Relative influence upon microwave emissivity of fine-scale stratigraphy,internal scattering,and dielectric properties     

Anthony W. England 《Pure and Applied Geophysics》1976,114(2):287-299

Summary The microwave emissivity of relatively low-loss media such as snow, ice, frozen ground, and lunar soil is strongly influenced by fine-scale layering and by internal scattering. Radiometric data, however, are commonly interpreted using a model of emission from a homogeneous, dielectric halfspace whose emissivity derives exclusively from dielectric properties. Conclusions based upon these simple interpretations can be erroneous. Examples are presented showing that the emission from fresh or hardpacked snow over either frozen or moist soil is governed dominantly by the size distribution of ice grains in the snowpack. Similarly, the thickness of seasonally frozen soil and the concentration of rock clasts in lunar soil noticeably affect, respectively, the emissivities of northern latitude soils in winter and of the lunar regolith. Petrophysical data accumulated in support of the geophysical interpretation of microwave data must include measurements of not only dielectric properties, but also of geometric factors such as finescale layering and size distributions of grains, inclusions, and voids.  相似文献   

A unified approach to a fragmental problem: Petrological and geochemical studies of lithic fragments from Apollo 15 soils     

Michael J. Drake  Judy W. Stoeser  Gordon G. Goles 《Earth and Planetary Science Letters》1973,20(3):425-439

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Local and regional components of western Aegean deformation extracted from 100 years of geodetic displacement measurements     

Andrew Curtis  Philip England  Robert Davies 《Geophysical Journal International》1997,130(3):623-639

Our objectives are as follows. First, we wish to develop a methodology to recover the long-term component of deformation from any set of distributed, time-averaged geodetic strain measurements that were subject to seismic disturbance, given a catalogue of local seismicity that occurred during the measurement period. Second, using seismic and geodetic data sets that span approximately 100 years, we apply this technique in the western Aegean to assess the role of local seismicity in regional deformation. The methodology is developed using a model for crustal deformation constructed from a long-term, smooth regional strain field combined with instantaneous, local perturbations from upper-crustal earthquakes approximated by static elastic dislocations. By inverting geodetic displacements for the smooth field while simultaneously floating influential but uncertain earthquake source parameters, an estimate of the regional component of deformation that is approximately independent of the seismicity can be made. In the western Aegean we find that the horizontal component of regional deformation can be described with minor inaccuracy by a quadratic relative displacement field. The principal horizontal extensional axes calculated from the regionally smooth displacement field agree in orientation with the T-axes of earthquakes in the region. These observations indicate that the instantaneous elastic strain of the 10 km thick seismogenic layer is driven by a stress field that is smooth on the scale of the geodetic network as a whole, 200-300 km.  相似文献   

The seismic signature of the Iapetus Suture beneath the North Sea     

Richard W. England 《Studia Geophysica et Geodaetica》1995,39(3):235-240

Summary Deep seismic reflection profiles across the Mid-North Sea High and the Anglo-Dutch basin record a number of intra-crustal and mantle events. When combined with interpretations of potential field data and surface geology, these can be attributed to the Iapetus Suture, beneath the Mid-North Sea High, and the remains of an Ordovician subduction zone, beneath the concealed Caledonide basement of eastern England.  相似文献   

The Younger Dryas and the Sea of Ancient Ice     

Raymond S. Bradley  John H. England 《Quaternary Research》2008,70(1):1-10

We propose that prior to the Younger Dryas period, the Arctic Ocean supported extremely thick multi-year fast ice overlain by superimposed ice and firn. We re-introduce the historical term paleocrystic ice to describe this. The ice was independent of continental (glacier) ice and formed a massive floating body trapped within the almost closed Arctic Basin, when sea-level was lower during the last glacial maximum. As sea-level rose and the Barents Sea Shelf became deglaciated, the volume of warm Atlantic water entering the Arctic Ocean increased, as did the corresponding egress, driving the paleocrystic ice towards Fram Strait. New evidence shows that Bering Strait was resubmerged around the same time, providing further dynamical forcing of the ice as the Transpolar Drift became established. Additional freshwater entered the Arctic Basin from Siberia and North America, from proglacial lakes and meltwater derived from the Laurentide Ice Sheet. Collectively, these forces drove large volumes of thick paleocrystic ice and relatively fresh water from the Arctic Ocean into the Greenland Sea, shutting down deepwater formation and creating conditions conducive for extensive sea-ice to form and persist as far south as 60°N. We propose that the forcing responsible for the Younger Dryas cold episode was thus the result of extremely thick sea-ice being driven from the Arctic Ocean, dampening or shutting off the thermohaline circulation, as sea-level rose and Atlantic and Pacific waters entered the Arctic Basin. This hypothesis focuses attention on the potential role of Arctic sea-ice in causing the Younger Dryas episode, but does not preclude other factors that may also have played a role.  相似文献   

Calculation of stresses in concrete ocean structures subjected to steady and time-varying temperatures,as influenced by creep     

G.L. England 《Applied Ocean Research》1979,1(1):33-41

The stress redistribution brought about by differential thermal creep in non-uniformly heated concrete structures is considered. Theory is presented which permits stresses to be evaluated in both the transient creep phase and in the limiting steady-state condition, from direct procedures, when temperatures are either time-invariant or vary cyclically in time. Illustrative numerical examples are presented and these reflect the dominant behaviour of flexurally restrained sections as occur in the walls of concrete oil containment structures. They are used also, to highlight some of the influential parameters on the stresses, e.g. magnitude of temperature crossfall through wall, ratio of maximum to minimum temperatures, and the nature of the cyclic variations of temperature with time.It is concluded that creep, coupled with non-uniform temperature, causes significant time-dependent variations of the stresses to occur. The theory presented forms a useful means of making stress predictions for specified states of temperature and helps to assess the probability of possible cracking in sections which might otherwise be assumed to be ‘safe’ from a conventional elastic calculation.The analyses relate to prestressed sections where cracking does not dominate, and to stress levels in the ‘working’ range for which creep is linearly related to stress.  相似文献   

Marine research in Israel     

Judy Carr 《Marine Policy》1977,1(4):343-344

A note on the main projects and concerns of the Israel Oceanographic and Limnological Research Institute at Haifa.  相似文献   

Textural and isotopic development of marble assemblages during the Barrovian-style M2 metamorphic event,Naxos, Greece     

Judy Baker  Alan Matthews 《Contributions to Mineralogy and Petrology》1994,116(1-2):130-144

A detailed petrological analysis of the marble assemblages observed within the M2 metamorphic complex on Naxos is presented. Two distinct periods of mineral growth are documented; the first is associated with prograde M2 metamorphism and the second with retrograde M2 metamorphism occurring during ductile extensional thinning of the complex. The textural and miner-alogical characteristics and the carbon and oxygen isotope compositions of each generation are described, and the P-T-X _{CO 2} conditions at which these two mineral generations were stable, and the compositions of the fluids present during metamorphism are characterised. Whereas the low variance and stable isotope compositions of prograde siliceous dolomite assemblages are consistent with internally buffered fluid evolution, the retrograde mineral generation is shown to have grown as a result of the infiltration of a water-rich fluid phase that transported silica, Al₂O₃, Na₂O and FeO into the host rocks. This observation, together with the stable isotope compositions of the retrograde calcite, and the fact that occurrences of veins of this type are limited to marbles in the highest grade areas (T>600° C) of the metamorphic complex, suggests that the fluids responsible for vein formation were generated during the crystallisation of melts as the metamorphic complex cooled from peak temperatures. The existence of this second generation of minerals has significant implications for previous studies of heat transport by fluid flow on Naxos, because many of the unusually low ¹⁸O compositions of pelites at high grades may be ascribable to the effects of interaction with retrograde M2 fluids, rather than with prograde fluids.  相似文献   

A forefin of Leptonectes solei from the Lower Jurassic (Pliensbachian) of Dorset,UK     

Dean R. Lomax  Judy A. Massare 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(6):770-773

An incomplete forefin in the collections of the National Museum of Wales, Cardiff, is herein assigned to the rare leptonectid species, Leptonectes solei, known only from the west Dorset coast. It is only the third specimen of the species and is smaller than both the holotype and referred specimen. The new specimen is from the Lower Jurassic (lower Pliensbachian, Charmouth Mudstone Formation, Tragophylloceras ibex Ammonite Zone, Acanthopleuroceras valdani Ammonite Subzone) of Seatown, Dorset, UK. It confirms that all three species of Leptonectes were present in the Pliensbachian and expands the known diversity of ichthyosaurs for that time period. We show that isolated forefins of Leptonectes can be assigned to a species with a high degree of confidence.  相似文献   

BAVARIAN LEAVENWORTH AND THE SYMBOLIC ECONOMY OF A THEME TOWN     

Stephen Frenkel  Judy Walton 《Geographical review》2000,90(4):559-584

ABSTRACT. Theme towns are an often‐overlooked but significant form of tourism in rural areas. Many a small town across the United States, faced with a declining resource‐based economy, has turned to “theming” as an economic‐development strategy. In hopes of creating an alluring landscape, the built environment is radically transformed, and a variety of invented traditions are instituted. This article explores one such place‐Leavenworth, Washington‐that “went Bavarian” in the 1960s and is widely viewed as a success story. We examine four interrelated concepts that produce the symbolic economy of Leavenworth: emulation of other theme towns, authenticity, visual difference, and place marketing. After discussing each, we turn to the questions of how residents are affected by tourism and what it is like to live in Leavenworth.  相似文献