Combined analysis of field and model data: A case study of the phosphate dynamics in the German Bight in summer 1994     

Th. Pohlmann  Th. Raabe  R. Doerffer  S. Beddig  U. Brockmann  S. Dick  M. Engel  K. -J. Hesse  P. König  B. Mayer  A. Moll  D. Murphy  W. Puls  H. -J. Rick  R. Schmidt-Nia  W. Schönfeld  J. Sündermann 《Ocean Dynamics》1999,51(2-3):331-353

  相似文献   

A geophysical survey of the De Gerlache Seamounts: preliminary results     

Rick A. Hagen  Karsten Gohl  Rainer Gersonde  Gehard Kuhn  David Völker  V. N. Kodagali 《Geo-Marine Letters》1998,18(1):19-25

 The De Gerlache Seamounts actually consist of two medium-sized guyots, with summits at depths of 350–600 m. Acoustic profiler data show no significant sediment on these guyots. Alkaline basalts dredged from the summit of the eastern guyot yield K/Ar ages between 20.1±1.0 and 23.2±1.2 Ma. Basement ridges and sediment-filled troughs between the guyots are associated with the prominent gravity anomaly extending north from the Antarctic margin. This structure possibly played a role in the guyot formation, however, the question of how the De Gerlache Seamounts are related to this gravity anomaly remains uncertain. Received: 13 February 1997 / Revision received: 30 September 1997  相似文献   

Atom Probe Tomography: Development and Application to the Geosciences     

Steven M. Reddy  David W. Saxey  William D. A. Rickard  Denis Fougerouse  Stephanie D. Montalvo  Rick Verberne  Arie van Riessen 《Geostandards and Geoanalytical Research》2020,44(1):5-50

Atom probe tomography (APT) is an analytical technique that provides quantitative three‐dimensional elemental and isotopic analyses at sub‐nanometre resolution across the whole periodic table. Although developed and mostly used in the materials science and semiconductor fields, recent years have seen increasing development and application in the geoscience and planetary science disciplines. Atom probe studies demonstrate compositional complexity at the nanoscale and provide fundamental new insights into the atom‐scale mechanisms taking place in minerals over geological time. Here, we provide an overview of APT, including the historical development and technical aspects of the instrumentation, and the fundamentals of data acquisition, data processing and data reconstruction. We also review previous studies and highlight the potential future applications of nanoscale geochemical studies of natural materials.  相似文献   

A protocol for coordinating post-tsunami field reconnaissance efforts in the USA     

Rick Wilson  Nathan Wood  Laura Kong  Mike Shulters  Kevin Richards  Paula Dunbar  Gen Tamura  Ed Young 《Natural Hazards》2015,75(3):2153-2165

  相似文献   

Effects of alumina refinery wastewater and signature metal constituents at the upper thermal tolerance of: 2. The early life stages of the coral Acropora tenuis     

Negri AP  Harford AJ  Parry DL  van Dam RA 《Marine pollution bulletin》2011,62(3):474-482

The success of early life history transitions of the coral Acropora tenuis were used as endpoints to evaluate thermal stress and the effects of wastewater discharged to a tropical marine environment. The studies assessed the effects of: (i) temperature; (ii) three signature metals of the wastewater, aluminium (Al), vanadium (V) and gallium (Ga); and (iii) the wastewater (at 27 °C and 32 °C) on fertilisation and larval metamorphosis. The median inhibition temperatures for fertilisation and metamorphosis were 32.8 °C and 33.0 °C, respectively. Fertilisation IC₅₀s for Al, V and Ga were 2997, 2884 and 3430 μg L⁻¹, respectively. Metamorphosis IC₅₀s for Al, V and Ga were 1945, 675 and 3566 μg L⁻¹, respectively. The wastewater only affected fertilisation and metamorphosis at moderate concentrations (IC₅₀s = 63% and 67%, v/v, respectively, at 27 °C), posing a low risk to this species in the field. The effects of wastewater and temperature on fertilisation and metamorphosis were additive.  相似文献   

Evaluation of TRIGRS (transient rainfall infiltration and grid-based regional slope-stability analysis)’s predictive skill for hurricane-triggered landslides: a case study in Macon County,North Carolina   总被引：2，自引：0，他引：2  

Zonghu Liao  Yang Hong  Dalia Kirschbaum  Robert F. Adler  Jonathan J. Gourley  Rick Wooten 《Natural Hazards》2011,58(1):325-339

The key to advancing the predictability of rainfall-triggered landslides is to use physically based slope-stability models that simulate the transient dynamical response of the subsurface moisture to spatiotemporal variability of rainfall in complex terrains. TRIGRS (transient rainfall infiltration and grid-based regional slope-stability analysis) is a USGS landslide prediction model, coded in Fortran, that accounts for the influences of hydrology, topography, and soil physics on slope stability. In this study, we quantitatively evaluate the spatiotemporal predictability of a Matlab version of TRIGRS (MaTRIGRS) in the Blue Ridge Mountains of Macon County, North Carolina where Hurricanes Ivan triggered widespread landslides in the 2004 hurricane season. High resolution digital elevation model (DEM) data (6-m LiDAR), USGS STATSGO soil database, and NOAA/NWS combined radar and gauge precipitation are used as inputs to the model. A local landslide inventory database from North Carolina Geological Survey is used to evaluate the MaTRIGRS’ predictive skill for the landslide locations and timing, identifying predictions within a 120-m radius of observed landslides over the 30-h period of Hurricane Ivan’s passage in September 2004. Results show that within a radius of 24 m from the landslide location about 67% of the landslide, observations could be successfully predicted but with a high false alarm ratio (90%). If the radius of observation is extended to 120 m, 98% of the landslides are detected with an 18% false alarm ratio. This study shows that MaTRIGRS demonstrates acceptable spatiotemporal predictive skill for landslide occurrences within a 120-m radius in space and a hurricane-event-duration (h) in time, offering the potential to serve as a landslide warning system in areas where accurate rainfall forecasts and detailed field data are available. The validation can be further improved with additional landslide information including the exact time of failure for each landslide and the landslide’s extent and run out length.  相似文献   

Satellite data and geographic information systems for fire and resource management in the Canadian arctic     

Helmut Epp  Rick Lanoville 《国际地球制图》2013,28(2):97-103

Abstract

A method of analyzing remotely sensed data, a geographic information system, and an intelligent fire management system have been developed to provide integrated resource data for fire and other resources management. Natural and cultural features were digitized from 1:50,000 topographic maps using a geographic information system (GIS) to cover the 29 communities below the tree line in the western Canadian Arctic. Landsat Thematic Mapper data covering the same area were classified into land cover or fuel types. Detailed information on each fire such as location, area burned, date of discovery, fire number, fire zone, fire class and source of ignition was obtained and added to each map sheet as attribute data. A generalized vegetation cover map using NOAA AVHRR data was also obtained. The Intelligent Fire Management Information System (IFMIS) integrates relational data bases, geographic information display, and expert systems. It also has a spatial analysis procedure for forest fire preparedness planning. Linking the weather to the forest fuels through the Fire Weather Index system (FWI) and the Fire Behaviour Prediction System (FBPS), fire danger and fire behaviour are calculated and displayed, cell‐by‐cell. Values‐at‐risk and fire suppression resources are used in the dispatching and planning component of the system. The planning component allows the user to evaluate the coverage of fire suppression resources under the prevalent forecast fire behaviour conditions. Through the integration of data from the above systems, a set of maps were created which were used to analyze fire behaviour potential, identify fire hazards, and provide a basis for settlement protection strategies within the context of other land use activities such as wildlife harvesting and recreational activities.  相似文献   

Radio Intra-Day Variability: Answers and Questions     

David L. Jauncey  Lucyna Kedziora-Chudczer  James E.J. Lovell  Jean-Pierre Macquart  George D. Nicolson  Rick A. Perley  John E. Reynolds  Anastasios K. Tzioumis  Mark H. Wieringa  Hayley E. Bignall 《Astrophysics and Space Science》2001,278(1-2):87-92

Intra-day variability (IDV) of active galactic nuclei (AGN) has been detected from gamma-ray energies to radio wavelengths. At high energies, such variability appears to be intrinsic to the sources themselves. However, at radio wavelengths, brightness temperatures as high as10¹⁸ to 10²¹ K are encountered if the IDV is intrinsic to the source. We discuss here the accumulating evidence showing that, at radio wavelengths where the highest brightness temperatures are encountered, interstellar scintillation (ISS) is the principal mechanism causing IDV. While ISS reduces the implied brightness temperatures, they still remain uncomfortably high. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Structural controls on sulphide deposition at the dyke–lava boundary, slow-spreading ocean crust, Macquarie Island     

Garry J. Davidson  Rick Varne  Anthony V. Brown  Robert Connell 《地学学报》2004,16(1):9-15

Ocean Drilling Program hole 504B revealed an ocean crust hydrothermal sulphur anomaly on the dyke–lava transition, with implications for global sulphur sinks. Here we confirm the presence of the anomaly sporadically along 7.5 km of dyke–basalt contact on the Macquarie Ridge at Macquarie Island, a 39–9.7 Ma slow‐spreading setting. Background contact‐zone pyrite S contents average 1845 p.p.m. across ～50 m. However, zones of small‐scale brittle faulting that commonly occur on and above the dyke–basalt contact average between 5000 and 11 000 p.p.m. S (20–30 m widths). These consist of steep ridge‐parallel faults and fault splays on the contact, overlain by up to 50 m of linked pyritic fault trellis. The contact zone faults are haloed by disseminated pyrite–chlorite, cross‐cut by quartz–chlorite–sphalerite and epidote‐cemented breccias, containing evidence of turbulent flow. The structural control on sulphur deposition is attributed to the active extensional slow spreading setting. With increasing extension, diffuse mixing across the contact was replaced by channellized flow and dynamic mixing in fault arrays. The magnitude of the dyke–lava transition sulphur sink must be reassessed to take account of this heterogeneity.  相似文献   

A discrete element model to link the microseismic energies recorded in caprock to geomechanics   总被引：1，自引：0，他引：1  

Cyrus Khazaei  Jim Hazzard  Rick Chalaturnyk 《Acta Geotechnica》2016,11(6):1351-1367

A discrete element model is presented to study slip-induced microseismic events along weak planes and crack-induced microseismic events within the intact rock for a representative elementary volume, REV, in the caprock of Weyburn reservoir. Also, the effect of varying factors such as orientation, coefficient of friction and elasticity of the weak plane on release of microseismic energies is studied. According to the results, for the conditions studied in this paper, the magnitudes of slip-induced events range from ~?1 to ?6, while crack-induced events range from ~?7 to ?11. Considering the capability of geophones, this suggests that events “recorded” in the caprock are more likely to have slip origins along weak planes than having crack origins within the intact rock. In order to show the applicability of the model in practice, the events recorded in the caprock of Weyburn from September to November of 2010 are analyzed. Also, a simple model is presented that correlates the amount of consumed energy per volume of the REV with the seismic energy released due to stick–slips along a weak plane. The results show that weak planes can be emissive even long before the failure of their surrounding is reached, and therefore, there can be a level of tolerance for the observed microseismic events in the caprock.  相似文献