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951.
Donald T. Resio Nancy J. Powell Mary A. Cialone Himangshu S. Das Joannes J. Westerink 《Natural Hazards》2017,88(3):1423-1449
In this paper, we propose a framework for quantifying risks, including (1) the effects of forecast errors, (2) the ability to resolve critical grid features that are important to accurate site-specific forecasts, and (3) a framework that can move us toward performance-based/cost-based decisions, within an extremely fast execution time. A key element presently lacking in previous studies is the interrelationship between the effects of combined random errors and bias in numerical weather prediction (NWP) models and bias and random errors in surge models. This approach examines the number of degrees of freedom in present forecasts and develops an equation for the quantification of these types of errors within a unified system, given the number of degrees of freedom in the NWP forecasts. It is shown that the methodology can be used to provide information on the forecasts and along with the combined uncertainty due to all of the individual contributions. A potential important benefit from studies using this approach would be the ability to estimate financial and other trade-offs between higher-cost “rapid” evacuation methods and lower-cost “slower” evacuation methods. Analyses here show that uncertainty inherent in these decisions depends strongly on forecast time and geographic location. Methods based on sets of surge maxima do not capture this uncertainty and would be difficult to use for this purpose. In particular, it is shown that surge model bias can play a dominant role in distorting the forecast probabilities. 相似文献
952.
Sorin Mihai Donald A. McFarlane 《Proceedings of the Geologists' Association. Geologists' Association》2010,121(3):319-325
Tens of thousands of palaeontological and archaeological remains were collected by William Pengelly during 19th century excavations of Kents Cavern, but are now widely dispersed between museums. This has previously precluded spatial analysis. We have now assembled available museum records into a single database, and, using our previously-reconstructed Pengelly excavation map as a base, we have been able to exploit the unique Pengelly location code to set up a GIS mapping system. This allows, for the first time, the analysis of spatial patterns. In addition, the GIS serves to highlight potential problems of recording or curation in the original data. Here we report on the construction of the GIS system and its first use in the analysis of spatial distribution of bear remains. The maps demonstrate that Ursus deningeri entered the cave through a now-sealed High Level Chamber entrance at the back of the cave in the middle Pleistocene, whereas Ursus arctos accessed the cave in the late Pleistocene through the now-sealed Northeast Gallery entrance. The denning areas are reconstructed as Labyrinth/Bear's Den for U. deningeri and Vestibule/Great Chamber for U. arctos. Considerable post-mortem re-distribution of the remains of both species is indicated. 相似文献
953.
Aggregation Methodology for the Circum-Arctic Resource Appraisal 总被引:1,自引:0,他引:1
This paper presents a methodology that intends to aggregate the results of a recent assessment of undiscovered conventional
oil and gas resources of the Arctic by the U.S. Geological Survey. The assessment occurred in 48 geologically defined regions
called assessment units. The methodology includes using assessor specified pair-wise correlations as the basis to construct
a correlation matrix. Sampling from this matrix generates more realistic uncertainty estimates of aggregated resources than
if assumptions of total independence or total dependence are made. The latter two assumptions result in overly narrow or overly
broad estimates. Aggregation results for resources in regions north of the Arctic Circle are presented. 相似文献
954.
Leif Kristensen Donald H. Lenschow David Gurarie Niels Otto Jensen 《Boundary-Layer Meteorology》2010,134(2):195-221
We have developed a simple, steady-state, one-dimensional second-order closure model to obtain continuous profiles of turbulent
fluxes and mean concentrations of non-conserved scalars in a convective boundary layer without shear. As a basic tool we first
set up a model for conserved species with standard parameterizations. This leads to formulations for profiles of the turbulent
diffusivity and the ratio of temperature-scalar covariance to the flux of the passive scalar. The model is then extended to
solving, in terms of profiles of mean concentrations and fluxes, the NO
x
–O3 triad problem. The chemical reactions involve one first-order reaction, the destruction of NO2 with decay time τ, and one second-order reaction, the destruction of NO and O3 with the reaction constant k. Since the fluxes of the sum concentrations of NO
x
= NO + NO2 and O3 + NO2 turn out to be constant throughout the boundary layer, the problem reduces to solving two differential equations for the
concentration and the flux of NO2. The boundary conditions are the three surface fluxes and the fluxes at the top of the boundary layer, the last obtained
from the entrainment velocity, and the concentration differences between the free troposphere and the top of the boundary
layer. The equations are solved in a dimensionless form by using 1/(kτ) as the concentration unit, the depth h of the boundary layer as the length unit, the convective velocity scale w
* as the velocity unit, and the surface temperature flux divided by w
* as the temperature unit. Special care has been devoted to the inclusion of the scalar–scalar covariance between the concentrations
of O3 and NO. Sample calculations show that the fluxes of the reactive species deviate significantly from those of non-reactive
species. Further, the diffusivities, defined by minus the flux divided by the concentration gradient may become negative for
reactive species in contrast to those of non-reactive species, which in the present model are never negative. 相似文献
955.
The expansivity of supercooled diopside liquid has been determined using techniques of container-based dilatometry. Two thermal
strategies have been employed, one in which the sample is brought to volumetric equilibrium by long-duration dwells at low
temperatures (817 °C) and one in which scanning dilatometry of the sample has been performed at somewhat higher temperatures
(890–913 °C). The results of both experiments yield a supercooled liquid expansivity for diopside liquid in the temperature
range of 817–913 °C of 84.4 ± 2.8 × 10−4 cm3/mol K. The expansivity is 65% higher than that obtained for diopside melt obtained at superliquidus temperatures using the
double bob Archimedean method. Combined fitting of the new low temperature, volume–temperature data from the present study
and the superliquidus data from the literature has been performed. The combined fit yields the following equations for the
volume–temperature relationship of diopside liquid (T=temperature in °C):
The standard error of the fit using both equations reproduces the volume–temperature data for diopside liquid within experimental
error. This result reconciles the disparate values of expansivity measured at low temperatures in the supercooled state and
at superliquidus temperatures and confirms the temperature-dependence of the expansivity of diopside liquid. Comparison with
previous low temperature estimates of melt volume and expansivity are discussed in light of these new results.
Received: 18 November 1999 / Accepted: 24 January 2000 相似文献
956.
Donald Cameron Watt 《Marine Policy》1979,3(3):211-224
The movement to establish coastalstate jurisdiction over a distance of 200 miles has its origins in President Truman's proclamation of September 1945 on the resources of the continental shelf and ‘certain high seas fisheries’. The author analyses the processes and motives which led to the proclamation, the US justification of its revolutionary policy statements, the reactions of other nations (in particular the warning of the UK and the parallel declaration of Mexico), and the subsequent assessment of the consequences of the action in the USA. 相似文献
957.
Donald F. Neidig 《Solar physics》1980,66(2):205-211
The solar rotation rate during 1967–1974 was measured from photographic observations of sunspots. The rates derived from isolated single spots and from bipolar groups were 14.38 ±0.02 and 14.71±0.05 deg per day equatorial sidereal, respectively. Year-to-year fluctuations in the bipolar group rates correlate with fluctuations in the Mt. Wilson spectroscopic rotation rates, while the isolated single spots show smaller, uncorrelated variations. A possible explanation for the fluctuations in the bipolar rates is year-to-year changes in the separation rates of the bipolar groups, rather than changes in the global solar rotation rate. The latter interpretation requires caution because (1) the sunspot rotation rates were derived from a limited amount of data (one month per year), and (2) the rotation rates were reduced to equatorial values assuming a differential rotation law {ie205-01}.Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation. 相似文献
958.
Craig Stroud Sasha Madronich Elliot Atlas Christopher Cantrell Alan Fried Brian Wert Brian Ridley Fred Eisele Lee Mauldin Richard Shetter Barry Lefer Frank Flocke Andy Weinheimer Mike Coffey Brian Heikes Robert Talbot Donald Blake 《Journal of Atmospheric Chemistry》2004,47(2):107-138
Local ozone production and loss rates for the arctic free troposphere (58–85° N, 1–6 km, February–May) during the TroposphericOzone Production about the Spring Equinox (TOPSE) campaign were calculated using a constrained photochemical box model. Estimates were made to assess the importance of local photochemical ozone production relative to transport in accounting for the springtime maximum in arctic free tropospheric ozone. Ozone production and loss rates from our diel steady-state box model constrained by median observations were first compared to two point box models, one run to instantaneous steady-state and the other run to diel steady-state. A consistent picture of local ozone photochemistry was derived by all three box models suggesting that differences between the approaches were not critical. Our model-derived ozone production rates increased by a factor of 28 in the 1–3 km layer and a factor of 7 in the 3–6 kmlayer between February and May. The arctic ozone budget required net import of ozone into the arctic free troposphere throughout the campaign; however, the transport term exceeded the photochemical production only in the lower free troposphere (1–3 km) between February and March. Gross ozone production rates were calculated to increase linearly with NOx mixing ratiosup to 300 pptv in February and for NOx mixing ratios up to 500 pptv in May. These NOx limits are an order of magnitude higher thanmedian NOx levels observed, illustrating the strong dependence ofgross ozone production rates on NOx mixing ratios for the majority of theobservations. The threshold NOx mixing ratio needed for netpositive ozone production was also calculated to increase from NOx 10pptv in February to 25 pptv in May, suggesting that the NOx levels needed to sustain net ozone production are lower in winter than spring. This lower NOx threshold explains how wintertime photochemical ozone production can impact the build-up of ozone over winter and early spring. There is also an altitude dependence as the threshold NOx neededto produce net ozone shifts to higher values at lower altitudes. This partly explains the calculation of net ozone destruction for the 1–3 km layerand net ozone production for the 3–6 km layer throughout the campaign. 相似文献
959.
Ethan?F.?BaxterEmail author Donald?J.?DePaolo 《Contributions to Mineralogy and Petrology》2004,146(6):657-670
Available constraints on metamorphic reaction rates derived from the study of natural systems are similar to, or slightly lower than, the bulk strain rates measured in the same rocks. Here, we explore whether this apparent relationship is merely coincidence or due to a more fundamental mechanistic link between reaction and strain. Grain boundary migration accommodated dislocation creep (GBMDC) or grain boundary diffusion creep (GBDC) (i.e. pressure solution), both of which involve dissolution-precipitation as we define it, will occur simultaneously with mineral reactions involving dissolution-precipitation in the presence of a non-zero deviatoric stress. The exact relationships between reaction and strain are different depending on whether GBMDC or GBDC is controlling strain, but the mechanistic link exists in both cases. We present theoretical arguments which show that bulk strain by GBMDC or GBDC, which may additionally be accommodated by processes not involving dissolution-precipitation, such as dislocation glide and climb or grain boundary sliding, should in most cases be somewhat faster than the bulk reaction rates as observed. With few exceptions, for natural metamorphic systems undergoing plastic deformation, strain rates provide an upper limit for bulk reaction rates occurring simultaneously in the same rocks. The data suggest that mineral reaction rates may typically be within one order of magnitude of the strain rate.Editorial responsibility: T.L. Grove 相似文献
960.
Peter B. Sak Donald M. Fisher Katherine Murphy 《Geochimica et cosmochimica acta》2004,68(7):1453-1472
Weathering rind thicknesses were measured on ∼ 200 basaltic clasts collected from three regionally extensive alluvial fill terraces (Qt 1, Qt 2, and Qt 3) preserved along the Pacific coast of Costa Rica. Mass balance calculations suggest that conversion of unweathered basaltic core minerals (plagioclase and augite) to authigenic minerals in the porous rind (kaolinite, allophane, gibbsite, Fe oxyhydroxides) is iso-volumetric and Ti and Zr are relatively immobile. The hierarchy of cation mobility (Ca ≈ Na > K ≈ Mg > Si > Al > Fe ≈ P) is similar to other tropical weathering profiles and is indicative of differential rates of mineral weathering (anorthite > albite ≈ hypersthene > orthoclase ? apatite). Alteration profiles across the cm-thick rinds document dissolution of plagioclase and augite and the growth of kaolinite, with subsequent dissolution of kaolinite and precipitation of gibbsite as weathering rinds age. The rate of weathering rind advance is evaluated using a diffusion-limited model which predicts a parabolic rate law for weathering rind thickness, rr, as a function of time, t(rr =), and an interface-limited model which predicts a linear rate law for weathering rind thickness as a function of time (rr = kappt). In these rate laws, κ is a diffusion parameter and kapp is an apparent rate constant. The rate of advance is best fit by the interface model.Terrace exposures are confined to the lower reaches of streams draining the Pacific slope near the coast where the stream gradient is less than ∼3 m/km, and terrace deposition is influenced by eustatic sea level fluctuations. Geomorphological evidence is consistent with terrace deposition coincident with sea level maxima when the stream gradient would be lowest. Assigning the most weathered regionally extensive terrace Qt 1 (mean rind thickness 6.9 ± 0. 6cm) to oxygen isotope stage (OIS) 7 (ca. 240 ka), and assuming that at time = 0 rind thickness = 0, it is inferred that terrace Qt 2 (rr = 2.9 ± 0.1 cm) is coincident with stage 5e (ca. 125 ka) and that Qt 3 (rr = 0.9 ± 0.1 cm) is consistent with OIS 3 (ca. 37 ka). These assignments yield a value of kapp of 8.6 × 10−13 cm s−1 (R2 = 0.99). Only this value satisfies both the existing age controls and yields ages coincident with sea level maxima. Using this value, elemental weathering release fluxes across a weathering rind from Qt 2 range from 6.0 × 10−9 mol Si m−2 s−1 to 2.5 × 10−11 mol K m−2 s−1. The rate of rind advance for the Costa Rican terraces is 2.8 × 10−7 m yr−1. Basalt rind formation rates in lower temperature settings described in the literature are also consistent with interface-controlled weathering with an apparent activation energy of about 50 kJ mol−1. Rates of rind formation in Costa Rica are an order of magnitude slower than reported for global averages of soil formation rates. 相似文献