Geostandards and Geoanalytical Research Bibliographic Review 2013     

Klaus Peter Jochum  Uwe Nohl  Beate Schwager  Brigitte Stoll  Philip Suesser  Ulrike Weis 《Geostandards and Geoanalytical Research》2014,38(4):513-515

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Investigation of the Stable Atmospheric Boundary Layer at Halley Antarctica   总被引：2，自引：2，他引：0  

Javier Sanz Rodrigo  Philip S. Anderson 《Boundary-Layer Meteorology》2013,148(3):517-539

Boundary-layer measurements from the Brunt Ice Shelf, Antarctica are analyzed to determine flux–profile relationships. Dimensionless quantities are derived in the standard approach from estimates of wind shear, potential temperature gradient, Richardson number, eddy diffusivities for momentum and heat, Prandtl number, mixing length and turbulent kinetic energy. Nieuwstadt local scaling theory for the stable atmospheric boundary-layer appears to work well departing only slightly from expressions found in mid-latitudes. An $E$ E – $l_{\mathrm{m}}$ l m single-column model of the stable boundary layer is implemented based on local scaling arguments. Simulations based on the first GEWEX Atmospheric Boundary-Layer Study case study are validated against ensemble-averaged profiles for various stability classes. A stability-dependent function of the dimensionless turbulent kinetic energy allows a better fit to the ensemble profiles.  相似文献   

What is at stake for Brazilian Amazonia in the climate negotiations     

Philip M. Fearnside 《Climatic change》2013,118(3-4):509-519

Issues left undecided at COP-18 in Doha in December 2012 are critical to containing the two greatest threats to Brazil’s Amazon forest: direct deforestation and forest loss through drought and fire provoked by climate change. Brazil’s diplomatic positions on the role of tropical forests in mitigating global warming currently call for receiving donations through a voluntary fund, but without generating carbon credit valid against emissions-reduction commitments by countries that accept limits on their national emissions (i.e., Annex I countries). Brazil has long rejected accepting a target (assigned amount), and has instead presented a non-binding “voluntary objective.” At COP-17 in Durban, Brazil expressed willingness to accept a commitment after 2020, but only if all of the rest of the world agreed to do the same. This author argues that Brazil’s national interests would be better served by accepting a target now and by supporting fully marketable carbon credit from Reducing Emissions from Deforestation and Degradation (REDD). The global goal of preventing mean temperature from increasing beyond 2 °C above pre-industrial levels would be much more likely to be achieved in practice with tropical forests fully included in a carbon market as part of an agreement for the period after 2012.  相似文献   

A high-pressure neutron diffraction study of the ferroelastic phase transition in RbCaF3     

Kevin S. Knight  William G. Marshall  Philip M. Hawkins 《Physics and Chemistry of Minerals》2014,41(6):461-472

The fluoroperovskite phase RbCaF₃ has been investigated using high-pressure neutron powder diffraction in the pressure range ~0–7.9 GPa at room temperature. It has been found to undergo a first-order high-pressure structural phase transition at ~2.8 GPa from the cubic aristotype phase to a hettotype phase in the tetragonal space group I4/mcm. This transition, which also occurs at ~200 K at ambient pressure, is characterised by a linear phase boundary and a Clapeyron slope of 2.96 × 10^?5 GPa K^?1, which is in excellent agreement with earlier, low-pressure EPR investigations. The bulk modulus of the high-pressure phase (49.1 GPa) is very close to that determined for the low-pressure phase (50.0 GPa), and both are comparable with those determined for the aristotype phases of CsCdF₃, TlCdF₃, RbCdF₃, and KCaF₃. The evolution of the order parameter with pressure is consistent with recent modifications to Landau theory and, in conjunction with polynomial approximations to the pressure dependence of the lattice parameters, permits the pressure variation of the bond lengths and angles to be predicted. On entering the high-pressure phase, the Rb–F bond lengths decrease from their extrapolated values based on a third-order Birch–Murnaghan fit to the aristotype equation of state. By contrast, the Ca–F bond lengths behave atypically by exhibiting an increase from their extrapolated magnitudes, resulting in the volume and the effective bulk modulus of the CaF₆ octahedron being larger than the cubic phase. The bulk moduli for the two component polyhedra in the tetragonal phase are comparable with those determined for the constituent binary fluorides, RbF and CaF₂.  相似文献   

Pacific Basin tsunami hazards associated with mass flows in the Aleutian arc of Alaska     

Christopher F. Waythomas  Philip Watts  Fengyan Shi  James T. Kirby 《Quaternary Science Reviews》2009,28(11-12):1006-1019

We analyze mass-flow tsunami generation for selected areas within the Aleutian arc of Alaska using results from numerical simulation of hypothetical but plausible mass-flow sources such as submarine landslides and volcanic debris avalanches. The Aleutian arc consists of a chain of volcanic mountains, volcanic islands, and submarine canyons, surrounded by a low-relief continental shelf above about 1000–2000 m water depth. Parts of the arc are fragmented into a series of fault-bounded blocks, tens to hundreds of kilometers in length, and separated from one another by distinctive fault-controlled canyons that are roughly normal to the arc axis. The canyons are natural regions for the accumulation and conveyance of sediment derived from glacial and volcanic processes. The volcanic islands in the region include a number of historically active volcanoes and some possess geological evidence for large-scale sector collapse into the sea. Large scale mass-flow deposits have not been mapped on the seafloor south of the Aleutian Islands, in part because most of the area has never been examined at the resolution required to identify such features, and in part because of the complex nature of erosional and depositional processes. Extensive submarine landslide deposits and debris flows are known on the north side of the arc and are common in similar settings elsewhere and thus they likely exist on the trench slope south of the Aleutian Islands. Because the Aleutian arc is surrounded by deep, open ocean, mass flows of unconsolidated debris that originate either as submarine landslides or as volcanic debris avalanches entering the sea may be potential tsunami sources.To test this hypothesis we present a series of numerical simulations of submarine mass-flow initiated tsunamis from eight different source areas. We consider four submarine mass flows originating in submarine canyons and four flows that evolve from submarine landslides on the trench slope. The flows have lengths that range from 40 to 80 km, maximum thicknesses of 400–800 m, and maximum widths of 10–40 km. We also evaluate tsunami generation by volcanic debris avalanches associated with flank collapse, at four locations (Makushin, Cleveland, Seguam and Yunaska SW volcanoes), which represent large to moderate sized events in this region. We calculate tsunami sources using the numerical model TOPICS and simulate wave propagation across the Pacific using a spherical Boussinesq model, which is a modified version of the public domain code FUNWAVE. Our numerical simulations indicate that geologically plausible mass flows originating in the North Pacific near the Aleutian Islands can indeed generate large local tsunamis as well as large transoceanic tsunamis. These waves may be several meters in elevation at distal locations, such as Japan, Hawaii, and along the North and South American coastlines where they would constitute significant hazards.  相似文献   

Win-win scenarios at the climate–development interface: Challenges and opportunities for stove replacement programs through carbon finance     

Gregory L. Simon  Adam G. Bumpus  Philip Mann 《Global Environmental Change》2012,22(1):275-287

Achieving win-win outcomes in environment–development programs is a laudable goal, but frequently difficult to realize. In this paper we review the possibilities for win-win climate and development outcomes in programs that distribute improved cookstoves with the use of carbon finance. We show that improved cookstove technologies form an important, if asymmetrical, environment–development interface, and illustrate the mutually supported local (development) and global (climate change) benefits of continued improved stoves use—where success in one program area is directly tied to benefits in the other. We also describe how program results are highly contextual and that, in practice, there are a number of challenges to achieving effective ‘win-win’ outcomes—including cultural, financial, governance and technological barriers. While carbon finance provides an opportunity to fund scaleable and enforceable stove programs, it may also introduce mutually supported impediments—where progress towards one set of program objectives, directly compromises progress towards other objectives. Drawing on development debates for improved cookstove use, scientific reports on stove-based greenhouse gas reductions, and preexisting case studies of carbon and non-carbon financed cookstoves in Peru, Uganda and Cambodia, we conclude that the challenge for future carbon financed improved cookstove projects will be to leverage inherent symbioses between climate and development arenas in order to overcome mutually supported impediments. Achieving substantive win-win conditions will require further scholarly and practical engagement to tackle the many outstanding challenges and uncertainties reviewed in this essay.  相似文献   

Towards a comprehensive distal andesitic tephrostratigraphic framework for New Zealand based on eruptions from Egmont volcano     

Phil Shane 《第四纪科学杂志》2005,20(1):45-57

The chronology and glass composition of 43 andesitic tephra layers in palaeolake sediments in northern New Zealand provide the basis for a fine‐resolution tephrostratigraphy of the interval 10–70 cal. ka. Their ages are constrained by 14 interbedded, (mostly) well‐dated rhyolitic tephra layers. The andesitic tephra have the potential to subdivide time intervals (1–5 kyr) bracketed by well known rhyolitic layers, including periods of rapid climate change such as the last glacial–interglacial transition and the Younger Dryas. The source of the distal andesitic tephra is identified as Egmont volcano (some 270 km S‐SW) on the basis of glass shard composition. The tephra contain high‐K₂O (3–6 wt%) andesitic‐dacitic (SiO₂ = 60–73 wt%) glass, with commonly heterogeneous shard populations (2–10 wt% SiO₂). Within stratigraphic intervals of < 10 kyr, individual tephra layers can be distinguished on the basis of their SiO₂ and K₂O contents, and variability in these contents can also be a distinguishing characteristic. The tephra record greatly extends the dated pyroclastic and geochemical record of Egmont volcano, and demonstrates that the volcano has frequently produced widely dispersed tephra over the last 70 kyr at a generally constant rate. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Predictions for the frequency and orbital radii of massive extrasolar planets     

Philip J. Armitage  Mario Livio  S. H. Lubow  J. E. Pringle 《Monthly notices of the Royal Astronomical Society》2002,334(1):248-256

We investigate the migration of massive extrasolar planets caused by gravitational interaction with a viscous protoplanetary disc. We show that a model in which planets form at 5 au at a constant rate, before migrating, leads to a predicted distribution of planets that is a steeply rising function of log( a ), where a is the orbital radius. Between 1 and 3 au, the expected number of planets per logarithmic interval in a roughly doubles. We demonstrate that, once selection effects are accounted for, this is consistent with current data, and then extrapolate the observed planet fraction to masses and radii that are inaccessible to current observations. In total, approximately 15 per cent of stars targeted by existing radial velocity searches are predicted to possess planets with masses  0.3< M _p sin( i )<10 M _J  and radii  0.1< a <5 au  . A third of these planets (around 5 per cent of the target stars) lie at the radii most amenable to detection via microlensing. A further  5–10  per cent of stars could have planets at radii of  5< a <8 au  that have migrated outwards. We discuss the probability of forming a system (akin to the Solar system) in which significant radial migration of the most massive planet does not occur. Approximately  10–15  per cent of systems with a surviving massive planet are estimated to fall into this class. Finally, we note that a smaller fraction of low-mass planets than high-mass planets is expected to survive without being consumed by the star. The initial mass function for planets is thus predicted to rise more steeply towards small masses than the observed mass function.  相似文献   

Ground‐based lidar measurements of aerosols during ACE‐2: instrument description, results, and comparisons with other ground‐based and airborne measurements     

Ellsworth J. Welton  Kenneth J. Voss  Howard R. Gordon  Hal Maring  Alexander Smirnov  Brent Holben  Beat Schmid  John M. Livingston  Philip B. Russell  Philip A. Durkee  Paola Formenti  Meinrat O. Andreae 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):636-651

A micro‐pulse lidar system (MPL) was used to measure the vertical and horizontal distribution of aerosols during the Aerosol Characterization Experiment 2 (ACE‐2) in June and July of 1997. The MPL measurements were made at the Izaña observatory (IZO), a weather station located on a mountain ridge (28°18' N, 16°30' W, 2367 m asl) near the center of the island of Tenerife, Canary Islands. The MPL was used to acquire aerosol backscatter, extinction, and optical depth profiles for normal background periods and periods influenced by Saharan dust from North Africa. System tests and calibration procedures are discussed, and an analysis of aerosol optical profiles acquired during ACE‐2 is presented. MPL data taken during normal IZO conditions (no dust) showed that upslope aerosols appeared during the day and dissipated at night and that the layers were mostly confined to altitudes a few hundred meters above IZO. MPL data taken during a Saharan dust episode on 17 July showed that peak aerosol extinction values were an order of magnitude greater than molecular scattering over IZO, and that the dust layers extended to 5 km asl. The value of the dust backscatter–extinction ratio was determined to be 0.027±0.007 sr⁻¹. Comparisons of the MPL data with data from other co‐located instruments showed good agreement during the dust episode.  相似文献   

Searching for the source regions of martian meteorites using MGS TES: Integrating martian meteorites into the global distribution of igneous materials on Mars     

Victoria E. HAMILTON  Philip R. CHRISTENSEN  Harry Y. McSWEEN  Joshua L. BANDFIELD 《Meteoritics & planetary science》2003,38(6):871-885

Abstract— The objective of this study was to identify and map possible source regions for all 5 known martian meteorite lithologies (basalt, lherzolite, clinopyroxenite, orthopyroxenite, and dunite) using data from the Mars Global Surveyor Thermal Emission Spectrometer (MGS TES). We deconvolved the TES data set using laboratory spectra of 6 martian meteorites (Los Angeles, Zagami, ALH A77005, Nakhla, ALH 84001, and Chassigny) as end members, along with atmospheric and surface spectra previously derived from TES data. Global maps (16 pixels/degree) of the distribution of each meteorite end member show that meteorite‐like compositions are not present at or above TES detectability limits over most of the planet's dust‐free regions. However, we have confidently identified local‐scale (100s‐1000s km²) concentrations of olivine‐ and orthopyroxene‐bearing materials similar to ALH A77005, Chassigny, and ALH 84001 in Nili Fossae, in and near Ganges Chasma, in the Argyre and Hellas basin rims, and in Eos Chasma. Nakhla‐like materials are identified near the detection limit throughout the eastern Valles Marineris region and portions of Syrtis Major. Basaltic shergottites were not detected in any spatially coherent areas at the scale of this study. Martian meteorite‐like lithologies represent only a minor portion of the dust‐free surface and, thus, are not representative of the bulk composition of the ancient crust. Meteorite‐like spectral signatures identified above TES detectability limits in more spatially restricted areas (<tens of km) are targets of ongoing analysis.  相似文献