Multiple re‐advances of a Lake Vättern outlet glacier during Fennoscandian Ice Sheet retreat,south‐central Sweden          下载免费PDF全文

Sarah L. Greenwood  Matt O'Regan  Henrik Swärd  Tom Flodén  Roman Ananyev  Denis Chernykh  Martin Jakobsson 《Boreas: An International Journal of Quaternary Research》2015,44(4):619-637

Lake Vättern represents a critical region geographically and dynamically in the deglaciation of the Fennoscandian Ice Sheet. The outlet glacier that occupied the basin and its behaviour during ice‐sheet retreat were key to the development and drainage of the Baltic Ice Lake, dammed just west of the basin, yet its geometry, extent, thickness, margin dynamics, timing and sensitivity to regional retreat forcing are rather poorly known. The submerged sediment archives of Lake Vättern represent a missing component of the regional Swedish deglaciation history. Newly collected geophysical data, including high‐resolution multibeam bathymetry of the lake floor and seismic reflection profiles of southern Lake Vättern, are used here together with a unique 74‐m sediment record recently acquired by drill coring, and with onshore LiDAR‐based geomorphological analysis, to investigate the deglacial environments and dynamics in the basin and its terrestrial environs. Five stratigraphical units comprise a thick subglacial package attributed to the last glacial period (and probably earlier), and an overlying >120‐m deglacial sequence. Three distinct retreat–re‐advance episodes occurred in southern Lake Vättern between the initial deglaciation and the Younger Dryas. In the most recent of these, ice overrode proglacial lake sediments and re‐advanced from north of Visingsö to the southern reaches of the lake, where ice up to 400 m thick encroached on land in a lobate fashion, moulding crag‐and‐tail lineations and depositing till above earlier glacifluvial sediments. This event precedes the Younger Dryas, which our data reveal was probably restricted to north‐central sectors of the basin. These dynamics, and their position within the regional retreat chronology, indicate a highly active ice margin during deglaciation, with retreat rates on average 175 m a^?1. The pronounced topography of the Vättern basin and its deep proglacial‐dammed lake are likely to have encouraged the dynamic behaviour of this major Fennoscandian outlet glacier.  相似文献   

Geogas transport in fractured hard rock – Correlations with mining seismicity at 3.54 km depth, TauTona gold mine, South Africa     

Johanna Lippmann-Pipke  Jörg Erzinger  Martin Zimmer  Christian Kujawa  Margaret Boettcher  Esta Van Heerden  Armand Bester  Hannes Moller  Nicole A. Stroncik  Zeev Reches 《Applied Geochemistry》2011,26(12):2134-2146

An on-site gas monitoring study has been conducted in the framework of an earthquake laboratory (The International NELSAM–DAFGAS projects) at the TauTona gold mine, South Africa. Five boreholes up to 60 m long were drilled at 3.54 km depth into the highly fractured Pretorius Fault Zone and instruments for chemical and seismic monitoring installed therein. Over the span of 4 years sensitive gas monitoring devices were continuously improved to enable the direct observation of geogas concentration variations in the DAFGAS borehole. The major gas concentrations are constant and air-like with about 78% N₂, 21% O₂, 1% Ar. The geogas components CO₂, CH₄, He and H₂ show the most interesting trends and variations on the minute-by-minute basis and significantly correlate with seismic data, while the ²²²Rn activity remains constant. Time series and cross correlation analysis allow the identification of different gas components (geogas and tunnel air) and the identification of two processes influencing the borehole gas composition: (1) pumping-induced tunnel air breakthrough through networks of initially water-saturated fault fractures; and (2) seismicity induced permeability enhancement of fault fractures to above ∼5 × 10^-10 m². The current set-up of the gas monitoring system is sensitive enough to quantify the resulting geogas transport during periods of intense blasting activities (including recorded blasts with seismic moment ?1 × 10⁹ Nm, located within 1000 m of the cubby) and, it is suggested, also during induced earthquakes, a final goal of the project.  相似文献   

Erratum to: Cosmogenic 10Be-derived denudation rates of the Eastern and Southern European Alps     

Kevin P. Norton  Friedhelm von Blanckenburg  Roman DiBiase  Fritz Schlunegger  Peter W. Kubik 《International Journal of Earth Sciences》2011,100(5):1225-1226

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Carbon production and export from Biscayne Bay,Florida. II. Episodic export of organic carbon     

Michael L. Incze  M.R. Roman 《Estuarine, Coastal and Shelf Science》1983,17(1):61-72

Seasonal meteorological events of high wind energy are important in the export of organic carbon from Biscayne Bay, Florida, by altering circulation and tidal flushing patterns coincident with increased resuspension. The accumulation of detrital organic carbon in the bay during productive summer months with light south-east breezes is reversed by the onset of the winter season and associated weekly cold fronts with sustained 15 knot northerly winds. The reversal of Biscayne Bay circulation patterns and increased discharge at Caesar's Creek result in an outwelling of dissolved organic carbon and particulate organic carbon. Southward advection at the seaward extremes of exchange channels prevents reintroduction of exported organic carbon by tidal currents.  相似文献   

The directional characteristics of lunar infrared radiation     

Roman U. Sexl  Hannelore Sexl  Hanns Stremnitzer  Donald G. Burkhard 《Earth, Moon, and Planets》1971,3(2):189-213

A theory of the directional characteristics of the lunar infrared radiation measured by Saari and Shorthill has been derived. This theory is in excellent agreement with experiment at all angles of observation and at all phase angles. The radiation law used to describe the angular dependence of the infrared radiation emitted by a flat element of the lunar surface is 0.85 cos + 0.22 cos², where is the angle between the surface normal and the direction of observation. This radiation law is subsequently modified by taking into account lunar surface roughness. We assume a surface covered in part with spherical craters of various depth to diameter ratios as a model for the lunar soil. Re-radiation within the craters has been accounted for. Extensive use is made of group theoretical and invariant tensor methods which enable us to show that most of the details of the radiation pattern do not depend on the detailed nature of the surface features assumed, but only on the average surface slope. A best fit to the Saari-Shorthill data has been obtained by assuming 50% of the lunar surface to be covered with craters with a depth to diameter ratio of 1:3, while the remainder of the surface is essentially flat. The mean deviation between theory and experiment is 4K.This work has been supported by the National Aeronautics and Space Administration under Contracts No. NAS8-20 385 and NAS8-25 585, Marshall Space Flight Center, Alabama.Receipt delayed due to postal strike in Great Britain.  相似文献   

LusTRE: a framework of linked environmental thesauri for metadata management     

Riccardo Albertoni  Monica De Martino  Paola Podestà  Andreas Abecker  Roman Wössner  Karsten Schnitter 《Earth Science Informatics》2018,11(4):525-544

The paper illustrates a Linked Thesaurus Framework for the Environment, named LusTRE, to facilitate data sharing across different environmental disciplines. It provides a knowledge infrastructure of multilingual thesauri and code lists, interlinking them so that they can be used as one integrated linked data source. This multilingual thesaurus is published according to the Linked Data Best Practices and supports metadata compilation and data discovery for describing and finding Environmental geodata. A human readable web interface is provided for the exploitation of LusTRE as well as a set of web services for programmatic access to the knowledge infrastructure. LusTRE has been exploited within the European directive INSPIRE and SEIS piloting testbeds implemented within the EU project eENVplus in order to support cross-border and cross-domain data sharing. It is aimed at supporting multilingual data search and query refinement. In order to show how interlinked content can help users to more easily express metadata within Spatial Data Infrastructures (SDI), LusTRE web services have been integrated within existing metadata editors and geoportals.  相似文献   

The death spiral of coal in the U.S.: will changes in U.S. Policy turn the tide?     

Roman Mendelevitch  Christian Hauenstein  Franziska Holz 《Climate Policy》2013,13(10):1310-1324

ABSTRACT

The administration of U.S. President Donald Trump has promised to stop the ongoing spiralling down of the U.S. coal industry. We discuss the origins of the decline and assess the effects of policy interventions by the Trump administration. We find that, with fierce competition from natural gas and renewables, a further decrease of coal consumption must be expected by the old and inefficient U.S. coal-fired electricity generation fleet. By contrast, we consider the overly optimistic (for coal producers) view of the U.S. Energy Information Agency, and test whether the tide for the U.S. coal industry could turn as a result of three potential support measures: (i) revoking the Clean Power Plan (CPP); (ii) facilitating access to the booming Asian market; and (iii) enhanced support for Carbon Capture, Transport and Storage (CCTS) technology. We investigate the short-term and long-term effects on U.S. coal production using a comprehensive partial equilibrium model of the world steam coal market, COALMOD-World (Holz, Haftendorn, Mendelevitch, & von Hirschhausen, 2016). We find that revoking the CPP could stop the downward trend of steam coal consumption in the U.S., but even allowing for additional exports, will not lead to a return of U.S. coal production to the levels of the 2000s, that is, over 900?Mt per year. When global steam coal use is aligned with the 2°C climate target, U.S. steam coal production drops to around 100?Mt per year by 2030 and below 50?Mt by 2050, even if CCTS is available and exports via the U.S. West Coast is possible.

Key policy insights

• Declining U.S. coal use is primarily caused by competition from natural gas and renewables not by environmental regulation of the coal sector.

• Without substantial policy support, U.S. coal-fired generation capacity will continue to decline rapidly.

• Revoking the Clean Power Plan will lead to about one eighth higher U.S. coal production in the next years.

• Carbon Capture, Transport and Storage does not prevent the rapid decline of coal use required under stringent climate policy.

• Even in the most extreme pro-coal scenarios with additional export possibilities, U.S. coal production will not return to its pre-2010 levels.

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A low order dynamical model for runoff predictability     

Olson  Roman  Timmermann  Axel  Lee  June-Yi  An  Soon-Il 《Climate Dynamics》2021,56(1-2):399-422

Climate Dynamics - Recent work has identified potential multi-year predictability in soil moisture (Chikamoto et al. in Clim Dyn 45(7–8):2213–2235, 2015). Whether this long-term...  相似文献   

Redshift evolution of angular diameters and surface brightness: how rigid are galactic measuring rods?     

Roman Tomaschitz 《Astrophysics and Space Science》2011,331(2):397-408

The effect of a cosmic time variation of Newton’s constant on galactic angular diameters, linear size, apparent magnitude, and surface brightness is investigated. The redshift scaling of the gravitational constant is proportional to the Hubble parameter, derived from the constancy of a moderate dimensionless ratio of fundamental constants, and manifested in galactic linear-size evolution. The latter is demonstrated by fitting the angular size–redshift relation to spectroscopically and photometrically selected samples of high-redshift rotators. The intrinsic luminosity evolution of the rotators and their magnitude–redshift and surface brightness–redshift relations are studied. The galactic luminosity scales with a power of the Hubble parameter, and the scaling exponent is inferred from a moderate dimensionless ratio involving the gravitational constant, the Galactic luminosity, and the velocity of the Galaxy in the microwave background. The fits are performed with a cosmic expansion factor derived from paleoplanetary surface temperatures. This expansion factor is tested by comparing the corresponding redshift evolution of the angular-size distance to the distance estimates of two samples of galaxy clusters.  相似文献   

Orbital structure of the GJ876 extrasolar planetary system based on the latest Keck and HARPS radial velocity data     

Roman V. Baluev 《Celestial Mechanics and Dynamical Astronomy》2011,111(1-2):235-266

We use full available array of radial velocity data, including recently published HARPS and Keck observatory sets, to characterize the orbital configuration of the planetary system orbiting GJ876. First, we propose and describe in detail a fast method to fit perturbed orbital configuration, based on the integration of the sensitivity equations inferred by the equations of the original N-body problem. Further, we find that it is unsatisfactory to treat the available radial velocity data for GJ876 in the traditional white noise model, because the actual noise appears autocorrelated (and demonstrates non-white frequency spectrum). The time scale of this correlation is about a few days, and the contribution of the correlated noise is about 2 m/s (i.e., similar to the level of internal errors in the Keck data). We propose a variation of the maximum-likelihood algorithm to estimate the orbital configuration of the system, taking into account the red noise effects. We show, in particular, that the non-zero orbital eccentricity of the innermost planet d, obtained in previous studies, is likely a result of misinterpreted red noise in the data. In addition to offsets in some orbital parameters, the red noise also makes the fit uncertainties systematically underestimated (while they are treated in the traditional white noise model). Also, we show that the orbital eccentricity of the outermost planet is actually ill-determined, although bounded by ~0.2. Finally, we investigate possible orbital non-coplanarity of the system, and limit the mutual inclination between the planets b and c orbits by 5°?C15°, depending on the angular position of the mutual orbital nodes.  相似文献