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291.
Julie A. Winkler Logan Soldo Ying Tang Todd Forbush David S. Douches Chris M. Long Courtney P. Leisner C. Robin Buell 《Climatic change》2018,151(2):275-287
Climate change is anticipated to influence all parts of agricultural production systems. However, the potential impacts on crop storage have rarely been assessed, even though storage is an important component of a grower’s marketing strategy and is essential for the continuous supply of a commodity for processors, exporters, and consumers. The Michigan chip-processing potato industry provides an example of the importance of crop storage. Michigan is the largest producer of chip-processing potatoes in the USA, and potatoes are stored on farms from September to June. We use an ensemble of climate projections developed for three future time slices (early, mid, and late century) from 16 climate models forced by three greenhouse gas concentration pathways to assess future changes in potato storage conditions. Our findings indicate an increased future demand for ventilation and/or refrigeration immediately after harvest and again in spring and early summer, even for the early-century time slice. Furthermore, the period of reliably cold storage temperatures during winter is anticipated, when averaged across all models, to shorten by 11–17 days in Michigan’s primary production area and 14–20 days in the more southern secondary area by mid-century, and by 15–29 days and 31–35 days, respectively, for the northern and southern production areas by late century. The level of uncertainty, as indicated by the ensemble range, is large, although the sign of the projected changes in storage parameters is consistent. This case study provides an example of the potentially large effects of climate change on the storage conditions for agricultural commodities. 相似文献
292.
Magmatic Differentiation at an Island-arc Caldera: Okmok Volcano, Aleutian Islands, Alaska 总被引:1,自引:0,他引:1
Finney Benjamin; Turner Simon; Hawkesworth Chris; Larsen Jessica; Nye Chris; George Rhiannon; Bindeman Ilya; Eichelberger John 《Journal of Petrology》2008,49(5):857-884
Okmok volcano is situated on oceanic crust in the central Aleutianarc and experienced large (15 km3) caldera-forming eruptionsat 12 000 years BP and 2050 years BP. Each caldera-forming eruptionbegan with a small Plinian rhyodacite event followed by theemplacement of a dominantly andesitic ash-flow unit, whereaseffusive inter- and post-caldera lavas have been more basaltic.Phenocryst assemblages are composed of olivine + pyroxene +plagioclase ± Fe–Ti oxides and indicate crystallizationat 1000–1100°C at 0·1–0·2 GPain the presence of 0–4% H2O. The erupted products followa tholeiitic evolutionary trend and calculated liquid compositionsrange from 52 to 68 wt % SiO2 with 0·8–3·3wt % K2O. Major and trace element models suggest that the moreevolved magmas were produced by 50–60% in situ fractionalcrystallization around the margins of the shallow magma chamber.Oxygen and strontium isotope data (18O 4·4–4·9,87Sr/ 86Sr 0·7032–0·7034) indicate interactionwith a hydrothermally altered crustal component, which led toelevated thorium isotope ratios in some caldera-forming magmas.This compromises the use of uranium–thorium disequilibria[(230Th/ 238U) = 0·849–0·964] to constrainthe time scales of magma differentiation but instead suggeststhat the age of the hydrothermal system is 100 ka. Modellingof the diffusion of strontium in plagioclase indicates thatmany evolved crystal rims formed less than 200 years prior toeruption. This addition of rim material probably reflects theremobilization of crystals from the chamber margins followingreplenishment. Basaltic recharge led to the expansion of themagma chamber, which was responsible for the most recent caldera-formingevent. KEY WORDS: Okmok; caldera; U-series isotopes; Sr-diffusion; time scales; Aleutian arc 相似文献
293.
William T. Kenny Gil Bohrer Timothy H. Morin Chris S. Vogel Ashley M. Matheny Ankur R. Desai 《Boundary-Layer Meteorology》2017,163(2):311-326
The CASES-99 experimental data are used to analyze turbulence behaviour under a range of stable conditions using an adaptive method based on Hilbert spectral analysis. The characteristic scales of intrinsic mode functions vary between different stratifications. The second-order Hilbert marginal spectra display clear separation between fine-scale turbulence and large-scale motions. After removing the large-scale motions, the statistical characteristics of the reconstructed signals confirm the distinction of different stratifications in the fine-scale range. The correlation coefficient analyses reveal that the Hilbert spectral analysis method separates turbulence from large-scale motions in the stable boundary layer. 相似文献
294.
Syn‐kinematic sedimentation at a releasing splay in the northern Minwun Ranges,Sagaing Fault zone,Myanmar: significance for fault timing and displacement
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Chris K. Morley 《Basin Research》2017,29(Z1):684-700
The Sagaing Fault zone is the largest active fault in SE Asia, whose current displacement rate of around 1.8 cm year?1 is well‐established from GPS data. Yet determining the timing of initiation and total displacement on the fault zone has proven controversial. The timing problem can potentially be resolved through a newly identified syn‐kinematic sedimentary section directly related to displacement on the Sagaing Fault in the northern Minwun Ranges. The northern part of the western strand of the Sagaing Fault has a releasing splay geometry that sets up a syn‐kinematic oblique‐extensional basin in its hangingwall, here called the North Minwun Basin. A series of thick ridges probably composed of alluvial fan and fluvial sandstones dipping between 20 and 70° to the north, and younging northwards comprise the basin fill over a distance of 40 km. Total stratigraphic thickness (not vertical thickness) is estimated at 25 km. The basin in terms of depositional geometries, large displacements, and large stratigraphic thickness and appearance on satellite images has parallels with the extensional Hornelen basin, Norway and the strike‐slip Ridge Basin, California. Minimum likely displacement on the fault strand is 40 km, and may possibly be in excess of 100 km. The remote and inaccessible basin has yet to be properly dated, likely ages range between Eocene and Miocene. When dated the basin will provide an important constraint on the timing of deformation. The potential for this basin to constrain the timing and displacement along the northern part of the Sagaing Fault has not been previously recognised. 相似文献
295.
Ute C. Herzfeld Craig S. Lingle Cecily Freeman Chris A. Higginson Michael P. Lambert Li-Her Lee Vera A. Voronina 《Mathematical Geology》1997,29(6):859-890
The Antarctic Ice Sheet plays a major role in the global system, and the large ice streams discharging into the circumpolar
sea represent its gateways to the world’s oceans. Satellite radar altimeter data provide an opportunity for mapping surface
elevation at kilometerresolution with meteraccuracy. Geostaristical methods have been developed for the analysis of these
data. Applications to Seasat data and data from the Geosat Exact Repeat Mission indicate that the grounding line of Lambert
Glacier/Amery Ice Shelf, the largest ice stream in East Antarctica, has advanced 10–12 km between 1978 and 1987–89. The objectives
of this paper are to explore possibilities and limitations of satellite-altimetry-based mapping to capture changes for shorter
time windows and for smaller areas, and to investigate some methodological aspects of the data analysis. We establish that
one season of radar altimeter data is sufficient for constructing a map. This allows study of interannual variation and is
the key for a limeseries analysis approach to study changes in ice streams. Maps of the lower Lambert Glacier and the entire
Amery Ice Shelf are presented for austral winters 1978, 1987, 1988, and 1989. As a first step toward understanding the dynamics
of the ice-stream/iceshelf system, elevation changes are calculated for grounded ice, the grounding zone, and floating ice.
In the absence of (sufficient) surface gravity control for the Lambert Glacier/Amery Ice Shelf area, altimetry-based maps
may facilitate improvement of geoid models as they provide constraints on the terrain correction in the inverse gravimetric
problem. 相似文献
296.
Chris O. Hunt 《GeoJournal》1997,41(2):101-109
The Quaternary deposits of the Mediterranean countries provide clear evidence of past environments, and of environmental change. Modern work enables the reinterpretation of these deposits and shows arid glacial stages and humid interglacial stages, with the Holocene characterised by considerable human impact, mostly resulting from agricultural activity. In this paper, examples of typical Mediterranean Quaternary lithofacies, including tufa and slope, fluvial, coastal, aeolian and cave deposits are described from the Maltese Islands. The deposits are correlated and their climatic signal is interpreted to provide a first modern assessment of Quaternary environmental change in the Maltese Islands. 相似文献
297.
298.
Anthony H. McDaniel Chris A. Cantrell James A. Davidson Richard E. Shetter Jack G. Calvert 《Journal of Atmospheric Chemistry》1991,12(3):211-227
The infrared absorption cross-sections for eight commonly used halogenated methanes and ethanes have been measured as a function of temperature from 203 to 293 K. High resolution spectra (0.03 cm-1) have been used to derive integrated band strengths and peak cross-sections associated with the spectral features in the infrared region from 600 to 1500 cm-2. The values obtained in this study are compared to those from previous reports, and recommendations are made for uses in atmospheric sensing and radiative energy transfer models. The observed temperature dependence in the spectral features is also discussed. 相似文献
299.
Chris Harris Brian R Watters P Bruce Groenewald 《Contributions to Mineralogy and Petrology》1991,107(1):100-111
Regional dolerite dykes of Mesozoic age in western Dronning Maud Land are variable in both major and trace element composition
and include picritic types (MgO>18 wt%). The range in incompatible element concentrations is considerable (e.g. Zr 40–478
ppm) and shows little correlation with MgO content. Both high-and low-Ti, Zr (HTZ and LTZ) magma types are present and there
is a spread of compositions between these types. Major element oxide variations in dykes having MgO>10 wt% indicate that olivine
and orthoyproxene fractionation occurred, presumably at an early high-pressure stage of magma evolution. Major element oxide
variations in dykes having MgO<10 wt% indicate control by olivine and clinopyroxene. A minority of the more evolved dykes
are compositionally similar to the nearby Kirwan basalts, but the majority cannot be related to the Kirwan basalts by any
simple petrogenetic process as they contain higher concentrations of incompatible elements and have higher Mg-numbers. The
HTZ Dronning Maud Land dolerites have incompatible trace element concentrations which are very similar to the HTZ basalt magma
types of the Karoo of southern Africa with the exception of lower K and Rb in DML dolerites. The HTZ dolerites occur in the
part of Dronning Maud Land which appears to have been tectonically stable since the Archaean and are not found to intrude
the surrounding high-grade (about 1000 Ma) metamorphic rocks of the Sverdrup Group. These data provide qualified support for
models which seek to relate spatially the HTZ Mesozoic basalt types of Gondwana to sources beneath stable Archaean cratons. 相似文献
300.