A Prediction of the Peak Sunspot Number for Solar Cycle 23     

Bounar  Khaled H.  Cliver  Edward W.  Boriakoff  Valentín 《Solar physics》1997,176(1):211-216

We use a precursor technique based on the geomagneticaa index during the decline (last 30%) of solar cycle 22 to predict a peak sunspot number of 158 (± 18) for cycle 23, under the assumption that solar minimum occurred in May 1996. This method appears to be as reliable as those that require a year of data surrounding the geomagnetic minimum, which typically follows the smoothed sunspot minimum by about six months.  相似文献   

Spectral reflectance‐compositional properties of spinels and chromites: Implications for planetary remote sensing and geothermometry     

Edward A. Cloutis  J. M. Sunshine  R. V. Morris 《Meteoritics & planetary science》2004,39(4):545-565

Abstract— Reflectance spectra of spinels and chromites have been studied as a function of composition. These two groups of minerals are spectrally distinct, which relates largely to differences in the types of major cations present. Both exhibit a number of absorption features in the 0.3–26 μm region that show systematic variations with composition and can be used to quantify or constrain certain compositional parameters, such as cation abundances, and site occupancies. For spinels, the best correlations exist between Fe²⁺ content and wavelength positions of the 0.46, 0.93, 2.8, Restrahelen, 12.3, 16.2, and 17.5 μm absorption features, Al and Fe³⁺ content with the wavelength position of the 0.93 μm absorption feature, and Cr content from the depth of the absorption band near 0.55 μm. For chromites, the best correlations exist between Cr content and wavelength positions of the 0.49, 0.59, 2, 17.5, and 23 μm absorption features, Fe²⁺ and Mg contents with the wavelength position of the 1.3 μm absorption feature, and Al content with the wavelength position of the 2 μm absorption feature. At shorter wavelengths, spinels and chromites are most readily distinguished by the wavelength position of the absorption band in the 2 μm region (<2.1 μm for spinels, >2.1 μm for chromite), while at longer wavelengths, spectral differences are more pronounced. The importance of being able to derive compositional information for spinels and chromites from spectral analysis stems from the relationship between composition and petrogenetic conditions (pressure, temperature, oxygen fugacity) and the widespread presence of spinels and chromites in the inner solar system. When coupled with the ability to derive compositional information for mafic silicates from spectral analysis, this opens up the possibility of deriving petrogenetic information for remote spinel‐ and chromite‐bearing targets from analysis of their reflectance spectra.  相似文献   

Breaking the 'redshift deadlock'– II. The redshift distribution for the submillimetre population of galaxies     

Itziar Aretxaga  David H. Hughes  Edward L. Chapin  Enrique Gaztañaga  James S. Dunlop  Rob J. Ivison 《Monthly notices of the Royal Astronomical Society》2003,342(3):759-801

  相似文献   

Mafic silicate mapping on Mars: effects of palagonitic material, multiple mafic silicates, and spectral resolution     

Edward A. Cloutis  James F. Bell III 《Icarus》2004,172(1):233-254

The visible to near-infrared spectral reflectance properties of intimate and areal pyroxene?+?palagonitic material mixtures as well as pure mafic silicates (low-calcium pyroxene, high-calcium pyroxene, pigeonite, olivine) and mixtures of these minerals were analyzed at high spectral resolution (5 nm) as well as with non-contiguous band passes equivalent to recent HST observations and the Pathfinder IMP in order to determine the quality and quantity of mineralogical information (end member compositions, abundances, and grain sizes) derivable in the presence of palagonitic material. In the case of pyroxene?+?palagonitic material mixtures, pyroxene is detectable at abundances as low as 10 wt%, and its composition can be constrained because (a) its diagnostic absorption feature (located near 1000 nm) persists even for high palagonitic material abundances, and (b) palagonitic material does not appreciably alter the wavelength position of this band (<4 nm variation). For broad band data (such as Pathfinder IMP band passes), different mafic silicates can be discriminated and palagonitic material abundances constrained using a variety of reflectance ratios and three-point “absorption band depths.” However, other properties of mafic silicate?±?palagonitic material assemblages, such as mafic silicate major element compositions, grain sizes, and end member abundances, generally cannot be rigorously quantified. The use of multiple reflectance ratios can, however, be used to identify relative changes in these properties, as most changes in mafic silicate?±?palagonitic material assemblage properties are characterized by a unique corresponding set of reflectance ratio variations. The observed spectral-assemblage property trends are consistent with those expected from the known spectral properties of the end members.  相似文献   

Micromechanically inspired investigation of cemented granular materials: part I—from X-ray micro tomography to measurable model variables     

Tengattini  Alessandro  Andò  Edward  Einav  Itai  Viggiani  Gioacchino 《Acta Geotechnica》2023,18(1):35-55

Acta Geotechnica - Cemented granular materials are abundant in nature and are often artificially produced. Their macroscopic behaviour is driven by small-scale material processes, which are...  相似文献   

A micro-investigation of unsaturated sand in mini-triaxial compression based on micro-CT image analysis     

Wang  Ji-Peng  Luan  Ji-Yuan  Gao  Xu-Guang  Liu  Tai-Heng  Andò  Edward  François  Bertrand 《Acta Geotechnica》2022,17(11):4799-4821

Acta Geotechnica - The mechanical behaviours of unsaturated soils are highly related to the water content and pore water and air distributions. Under the context of climate change, geo-disasters...  相似文献   

Comparison between scarp and dip-slope rivers of the Cotswold Hills,UK     

Jonathan D. Paul  Nick Watson  Edward Tuckwell 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(1):57-69

The Cotswold Hills, southwest UK, are properly described as a cuesta, with a steep, west-facing scarp slope and a plateau-like dip slope. Drainage reflects this surface morphology, with most rivers flowing southeast along topographic and stratigraphic dip. Here, we compare two superficially highly similar rivers – the Frome and Churn – whose sources are nearly coincident, but whose behaviour dramatically diverges thereafter. We examine longitudinal profiles, channel steepness, predicted discharge, and valley shapes, using digital topographic data. River discharge and water hardness/temperature values were obtained at seven sites on the Churn and nine on the Frome over a two-year sampling campaign, delineated into summer and winter phases. Nearly 100 borehole records were interrogated from the two catchments in order to assess groundwater level variations. The Frome, flowing west against regional dips, develops a steep course and has carved a deep and wide valley that exposes the full sequence of Cotswold Jurassic stratigraphy. On the other hand, discharge and channel gradients are lower for the dip-slope Churn, whose valley exposes less stratigraphy and fewer springs. Our measurements of river water hardness and temperature suggest that a greater proportion of groundwater flows into the Frome, regulating discharge and maintaining baseflow over summer. We suggest that flank uplift of the Cotswolds is at least part of the reason for the higher incision rates of the River Frome, leading to its intersecting a greater number of highly transmissive fractures that contribute to its discharge. In turn, the increased discharge could positively impact local incision rates.  相似文献   

Employing Internet GIS Surveys to Characterize Recreational Boating Travel Patterns          下载免费PDF全文

Yue Cui  Edward Mahoney 《Transactions in GIS》2015,19(1):42-62

Spatial factors are fundamental features of the tourism and recreation phenomenon. In terms of recreational boating, scholars are interested both in boaters' spatial distribution and movement patterns and in the factors associated with their movements, e.g. travel costs, environmental impacts, and social impacts of the movements. Spatial factors are also key to policymakers' decisions about where to establish new boating facilities, how protected areas are used by boaters and in crafting policy that minimizes conflict between recreational boating and other waterway uses. However, systematic studies regarding the recreationist movement are scant, especially at the fine geographic level. One reason for the lack of research is that gathering spatial data presents significant practical problems. In the Florida Saltwater Fishing Study, we integrated Google Map APIs into the online survey instrument to collect spatially‐referenced data regarding boaters' movement on water. Results appear to be accurate, highly cost effective, and easily integrated with other survey information such as angler catch, effort, expenditures and attitudes.  相似文献   

Modal abundances of pyroxene,olivine, and mesostasis in nakhlites: Heterogeneity,variation, and implications for nakhlite emplacement          下载免费PDF全文

Catherine M. Corrigan  Michael A. Velbel  Edward P. Vicenzi 《Meteoritics & planetary science》2015,50(9):1497-1511

Nakhlites, clinopyroxenite meteorites from Mars, share common crystallization and ejection ages, suggesting that they might have been ejected from the same place on Mars by the same ejection event (impact) and are different samples of the same thick volcanic flow unit or shallow sill. Mean modal abundances and abundance ranges of pyroxene, olivine, and mesostasis vary widely among different thin‐sections of an individual nakhlite. Lithologic heterogeneity is the main factor contributing to the observed modal‐abundance variations measured in thin‐sections prepared from different fragments of the same stone. Two groups of nakhlites are distinguished from one another by which major constituent varies the least and the abundance of that constituent. The group consisting of Nakhla, Lafayette, Governador Valadares, and the Yamato nakhlite pairing group is characterized by low modal mesostasis and pyroxene‐olivine covariance, whereas the group consisting of the Miller Range nakhlite pairing group and Northwest Africa 5790 is characterized by low modal olivine and pyroxene‐mesostasis covariance. These two groups sample the slowest‐cooled interior portion and the chilled margin, respectively, of the nakhlite emplacement body as presently understood, and appear to be also related to recently proposed nakhlite groups independently established using compositional rather than petrographic observations. Phenocryst modal abundances vary with inferred depth in the nakhlite igneous body in a manner consistent with solidification of the nakhlite stack from dynamically sorted phenocryst‐rich magmatic crystal‐liquid mush.  相似文献   

Cosmogenic dating of Late Pleistocene glaciation,southern tropical Andes,Peru          下载免费PDF全文

Jeremy D. Shakun  Peter U. Clark  Shaun A. Marcott  Edward J. Brook  Nathaniel A. Lifton  Marc Caffee  William R. Shakun 《第四纪科学杂志》2015,30(8):841-847

  相似文献