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41.
Shorelines are recognized as unique features on Earth. They have valuable properties for a diverse user community. At present, photogrammetry is the most popular technique used to capture a shoreline. With improved resolution and accuracy, commercial high-resolution satellite imagery is demonstrating a great potential in the photogrammetry application domain. One example is the utilization of IKONOS satellite imagery in shoreline extraction. IKONOS panchromatic imagery has a resolution of approximately one meter as well as the capabilities of stereo imaging. This article presents the results of an experiment in which we attempted to improve IKONOS Rational Functions (RF) for a better ground accuracy and to employ the improved RF for 3-D shoreline extraction using 1-meter panchromatic stereo images in a Lake Erie coastal area. Two approaches were investigated. One was to rectify the ground coordinates derived from vendor-provided RF coefficients using ground control points (GCPs). The other was to refine the RF coefficients using the GCPs. We compare the results from these two approaches. An assessment of the shoreline extracted from IKONOS images compared with the existing shoreline is also conducted to demonstrate the potential of the IKONOS imagery for shoreline mapping. 相似文献
42.
Current observations taken at depths between 630 and 830 m from the west coast South Island continental slope exhibit one‐ to four‐weekly periodicities superimposed on the semi‐diurnal tide. These variable flows at 630 m and otter large, longer‐timescale events have a significart onshore/offshore component of flow which leads to a similar transport of alongshore momentum and heat. 相似文献
43.
Dissolved oxygen as an indicator of bioavailable dissolved organic carbon in groundwater 总被引:1,自引:0,他引:1
Concentrations of dissolved oxygen (DO) plotted vs. dissolved organic carbon (DOC) in groundwater samples taken from a coastal plain aquifer of South Carolina (SC) showed a statistically significant hyperbolic relationship. In contrast, DO-DOC plots of groundwater samples taken from the eastern San Joaquin Valley of California (CA) showed a random scatter. It was hypothesized that differences in the bioavailability of naturally occurring DOC might contribute to these observations. This hypothesis was examined by comparing nine different biochemical indicators of DOC bioavailability in groundwater sampled from these two systems. Concentrations of DOC, total hydrolysable neutral sugars (THNS), total hydrolysable amino acids (THAA), mole% glycine of THAA, initial bacterial cell counts, bacterial growth rates, and carbon dioxide production/consumption were greater in SC samples relative to CA samples. In contrast, the mole% glucose of THNS and the aromaticity (SUVA(254)) of DOC was greater in CA samples. Each of these indicator parameters were observed to change with depth in the SC system in a manner consistent with active biodegradation. These results are uniformly consistent with the hypothesis that the bioavailability of DOC is greater in SC relative to CA groundwater samples. This, in turn, suggests that the presence/absence of a hyperbolic DO-DOC relationship may be a qualitative indicator of relative DOC bioavailability in groundwater systems. 相似文献
44.
Kushendratno John S. Pallister Kristianto Farid Ruskanda Bina Wendy McCausland Simon Carn Nia Haerani Julia Griswold Ron Keeler 《Bulletin of Volcanology》2012,74(7):1581-1609
Soputan is a high-alumina basalt stratovolcano located in the active North Sulawesi-Sangihe Islands magmatic arc. Although immediately adjacent to the still geothermally active Quaternary Tondono Caldera, Soputan’s magmas are geochemically distinct from those of the caldera and from other magmas in the arc. Unusual for a basalt volcano, Soputan produces summit lava domes and explosive eruptions with high-altitude ash plumes and pyroclastic flows—eight explosive eruptions during the period 2003–2011. Our field observations, remote sensing, gas emission, seismic, and petrologic analyses indicate that Soputan is an open-vent-type volcano that taps basalt magma derived from the arc-mantle wedge, accumulated and fractionated in a deep-crustal reservoir and transported slowly or staged at shallow levels prior to eruption. A combination of high phenocryst content, extensive microlite crystallization and separation of a gas phase at shallow levels results in a highly viscous basalt magma and explosive eruptive style. The open-vent structure and frequent eruptions indicate that Soputan will likely erupt again in the next decade, perhaps repeatedly. Explosive eruptions in the Volcano Explosivity Index (VEI) 2–3 range and lava dome growth are most probable, with a small chance of larger VEI 4 eruptions. A rapid ramp up in seismicity preceding the recent eruptions suggests that future eruptions may have no more than a few days of seismic warning. Risk to population in the region is currently greatest for villages located on the southern and western flanks of the volcano where flow deposits are directed by topography. In addition, Soputan’s explosive eruptions produce high-altitude ash clouds that pose a risk to air traffic in the region. 相似文献
45.
Filiz Bilgili Hans-Jürgen Götze Roman Pašteka Sabine Schmidt Ron Hackney 《International Journal of Earth Sciences》2009,98(3):571-583
An unsolved problem of regional importance for both the evolution and structure of the Northwest German Basin is the existence
or non-existence of the so-called Bramsche Massif. Explaining the nature of this massif and the cause of a related strong,
positive Bouguer anomaly (Bramsche Anomaly) is critical. In the study described here, we tested an existing “intrusion model”
against a newer “inversion model” in the southern Northwest German Basin. In the intrusion model, the strongly-positive Bouguer
anomaly represents the gravity effect of an intrusion at depths between 6 and 10 km. More recent interpretations invoke tectonic
inversion rather than intrusion to explain increased burial and the low level of hydrocarbon maturity found in boreholes.
We tested these different interpretations by constructing 3D forward density models to 15 km depth. The intrusion model was
updated and adjusted to incorporate recent data and we also modelled pre-Zechstein structures using different scenarios. The
final model has a very good fit between measured and modelled gravity fields. Based on currently available seismic and structural
models, as well as borehole density measurements, we show that the positive Bouguer anomaly cannot be modeled without a high-density,
intrusive-like body at depth. However, further in-sight into the crustal structures of the Bramsche region requires more detailed
investigations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
46.
The applicability of the horizontal-to-vertical (H/V) ambient-noise spectral ratio for characterizing earthquake site effects caused by near-surface topography and velocity structures was evaluated at sites underlain by thick (i.e. >100 m) sediment deposits near the southern-end of the New Madrid seismic zone in the central United States. Three-component ambient-noise and velocity models derived from seismic (shear-wave) refraction/reflection surveys showed that a relatively horizontal, sharp shear-wave velocity interface in the soil column resulted in an H/V spectral ratio with a single well-defined peak. Observations at sites with more than one sharp shear-wave velocity contrast and horizontally arranged soil layers resulted in at least two well-defined H/V spectral ratio peaks. Furthermore, at sites where there were sharp shear-wave velocity contrasts in nonhorizontal, near-surface soil layers, the H/V spectra exhibited a broad-bandwidth, relatively low-amplitude signal instead of a single well-defined peak. 相似文献
47.
Differential developmental toxicity of naphthoic acid isomers in medaka (Oryzias latipes) embryos 总被引:1,自引:0,他引:1
Michael W. Carney Kyle Erwin Ron Hardman Bonny Yuen David C. Volz David E. Hinton Seth W. Kullman 《Marine pollution bulletin》2008,57(6-12):255
Polycyclic aromatic hydrocarbons (PAHs) are widespread persistent pollutants that readily undergo biotic and abiotic conversion to numerous transformation products in rivers, lakes and estuarine sediments. Here we characterize the developmental toxicity of four PAH transformation products each structural isomers of hydroxynaphthoic acid: 1H2NA, 2H1NA, 2H3NA, and 6H2NA. Medaka fish (Oryzias latipes) embryos and eleutheroembryos were used to determine toxicity. A 96-well micro-plate format was used to establish a robust, statistically significant platform for assessment of early life stages. Individual naphthoic acid isomers demonstrated a rank order of toxicity with 1H2NA > 2H1NA > 2H3NA > 6H2NA being more toxic. Abnormalities of circulatory system were most pronounced including pericardial edema and tube heart. To determine if HNA isomers were AhR ligands, spatial-temporal expression and activity of CYP1A was measured via in vivo EROD assessments. qPCR measurement of CYP1A induction proved different between isomers dosed at respective concentrations affecting 50% of exposed individuals (EC50s). In vitro, all ANH isomers transactivated mouse AhR using a medaka CYP1A promoter specific reporter assay. Circulatory abnormalities followed P450 induction and response was consistent with PAH toxicity. A 96-well micro-plates proved suitable as exposure chambers and provided statistically sound evaluations as well as efficient toxicity screens. Our results demonstrate the use of medaka embryos for toxicity analysis thereby achieving REACH objectives for the reduction of adult animal testing in toxicity evaluations. 相似文献
48.
49.
Michael J. Hollaway Keith J. Beven Clare Mc W. H. Benskin Adrian L. Collins Robert Evans Peter D. Falloon Kirsty J. Forber Kevin M. Hiscock Ron Kahana Christopher J. A. Macleod Mary C. Ockenden Martha L. Villamizar Catherine Wearing Paul J. A. Withers Jian G. Zhou Nicholas J. Barber Philip M. Haygarth 《水文研究》2018,32(17):2779-2787
River discharge and nutrient measurements are subject to aleatory and epistemic uncertainties. In this study, we present a novel method for estimating these uncertainties in colocated discharge and phosphorus (P) measurements. The “voting point”‐based method constrains the derived stage‐discharge rating curve both on the fit to available gaugings and to the catchment water balance. This helps reduce the uncertainty beyond the range of available gaugings and during out of bank situations. In the example presented here, for the top 5% of flows, uncertainties are shown to be 139% using a traditional power law fit, compared with 40% when using our updated “voting point” method. Furthermore, the method is extended to in situ and lab analysed nutrient concentration data pairings, with lower uncertainties (81%) shown for high concentrations (top 5%) than when a traditional regression is applied (102%). Overall, for both discharge and nutrient data, the method presented goes some way to accounting for epistemic uncertainties associated with nonstationary physical characteristics of the monitoring site. 相似文献
50.
Ron Johnston Derek Gregory Geraldine Pratt Michael Watts Sarah Whatmore 《Geoforum》2008,39(3):1105-1107
A reply to a recent paper by Setten. 相似文献