The interpretation of sunspot magnetic field observations     

M. G. Adam 《Solar physics》1985,96(1):27-34

Magnetic field strengths and directions of the lines of force have been measured over two large sunspots in 1975 and 1976 using Treanor's method. Further refinements in observational technique reduce the effects of instrumental polarization to a small phase change, and the reduction procedure has been made more objective. The new observations confirm the existence of differences between the polarization states of the red and violet Zeeman -components in some regions of the spots. These differences, which are especially associated with light bridges and streamers, are attributed to magneto-optical effects, coupled with Doppler shifts, in extraneous material lying over the spots.  相似文献   

Storylines: an alternative approach to representing uncertainty in physical aspects of climate change     

Theodore G. Shepherd  Emily Boyd  Raphael A. Calel  Sandra C. Chapman  Suraje Dessai  Ioana M. Dima-West  Hayley J. Fowler  Rachel James  Douglas Maraun  Olivia Martius  Catherine A. Senior  Adam H. Sobel  David A. Stainforth  Simon F. B. Tett  Kevin E. Trenberth  Bart J. J. M. van den Hurk  Nicholas W. Watkins  Dimitri A. Zenghelis 《Climatic change》2018,147(3-4):555-569

Investigating the relationships between climate extremes and crop yield can help us understand how unfavourable climatic conditions affect crop production. In this study, two statistical models, multiple linear regression and random forest, were used to identify rainfall extremes indices affecting wheat yield in three different regions of the New South Wales wheat belt. The results show that the random forest model explained 41–67% of the year-to-year yield variation, whereas the multiple linear regression model explained 34–58%. In the two models, 3-month timescale standardized precipitation index of Jun.–Aug. (SPI_JJA), Sep.–Nov. (SPI_SON), and consecutive dry days (CDDs) were identified as the three most important indices which can explain yield variability for most of the wheat belt. Our results indicated that the inter-annual variability of rainfall in winter and spring was largely responsible for wheat yield variation, and pre-growing season rainfall played a secondary role. Frequent shortages of rainfall posed a greater threat to crop growth than excessive rainfall in eastern Australia. We concluded that the comparison between multiple linear regression and machine learning algorithm proposed in the present study would be useful to provide robust prediction of yields and new insights of the effects of various rainfall extremes, when suitable climate and yield datasets are available.  相似文献   

Predictable and Unpredictable Components of the Summer East Asia–Pacific Teleconnection Pattern     

Xiaozhen LIN  Chaofan LI  Riyu LU  Adam A.SCAIFE 《大气科学进展》2018,35(11):1372-1380

The East Asia–Pacific(EAP) teleconnection pattern is the dominant mode of circulation variability during boreal summer over the western North Pacific and East Asia, extending from the tropics to high latitudes. However, much of this pattern is absent in multi-model ensemble mean forecasts, characterized by very weak circulation anomalies in the mid and high latitudes. This study focuses on the absence of the EAP pattern in the extratropics, using state-of-the-art coupled seasonal forecast systems. The results indicate that the extratropical circulation is much less predictable, and lies in the large spread among different ensemble members, implying a large contribution from atmospheric internal variability. However,the tropical–mid-latitude teleconnections are also relatively weaker in models than observations, which also contributes to the failure of prediction of the extratropical circulation. Further results indicate that the extratropical EAP pattern varies closely with the anomalous surface temperatures in eastern Russia, which also show low predictability. This unpredictable circulation–surface temperature connection associated with the EAP pattern can also modulate the East Asian rainband.  相似文献   

Navigating through SPASE to heliospheric and magnetospheric data   总被引：1，自引：1，他引：0  

Jan Merka  Thomas W. Narock  Adam Szabo 《Earth Science Informatics》2008,1(1):35-42

Virtual observatories have been introduced by the astrophysics community as an environment connecting distributed data sources with a unified interface. The heliophysics community soon recognized that they faced a similar problem of many distributed data sets with varying amount of information about them and several discipline specific virtual observatories have been established. Two of them, the virtual heliospheric observatory (VHO) and the virtual magnetospheric observatory (VMO), share a common architecture design with development efforts oriented towards a structured data search. This paper describes the VHO/VMO middleware and its components from metadata preparation and processing to the user interface.  相似文献   

Deriving incline values for street networks from voluntarily collected GPS traces   总被引：1，自引：0，他引：1  

Steffen John  Adam Rousell  Marc-O. Löwner  Alexander Zipf 《制图学和地理信息科学》2017,44(2):152-169

ABSTRACT

When producing optimal routes through an environment, considering the incline of surfaces can be of great benefit in a number of use cases. For instance, steep segments need to be avoided for energy-efficient routes and for routes that are suitable for mobility-restricted people. Such incline information may be derived from digital elevation models (DEMs). However, the corresponding data capturing methods (e.g. airborne LiDAR, photogrammetry, and terrestrial surveying) are expensive. Current low-cost and open-licensed DEM (e.g. Shuttle Radar Topography Mission [SRTM] and Advanced Spaceborne Thermal Emission and Reflection Radiometer [ASTER]) generally do not have sufficient horizontal resolution or vertical accuracy, and lack a global coverage. Therefore, we have investigated an alternative low-cost approach which derives street incline values from GPS traces that have been voluntarily collected by the OpenStreetMap contributors. Despite the poor absolute accuracy of this data, the relative accuracy of traces seems to be sufficient enough to compute incline values with reasonable accuracy. A validation shows that the accuracy of incline values calculated from GPS traces slightly outperforms incline values derived from SRTM-1 DEM, though results depend on how many traces per street segment are used for computation.  相似文献   

Effect of hot dry summer tropical climate on forage intake and milk yield in Holstein–Friesian and indigenous zebu cows in Sudan     

Muna Mahjoub M Ahmed  Adam Ibrahim El Amin 《Journal of Arid Environments》1997,35(4):737-746

The effects of dry summer ambient temperature on some physiological and productive responses were studied in an exotic European breed (Holstein–Friesian) and a local zebu breed (Butana ecotype) of cattle in Sudan. Rectal temperature and respiration rate were positively correlated, and dry matter intake and milk yield were negatively correlated with variation in ambient temperature. However, significant adverse effects on high ambient temperature were only observed in the exotic breed.  相似文献   

Book reviews     

Adam E. Sieminski  Michael E. Hohn 《Natural Resources Research》1997,6(3):237-238

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Trace element partitioning between silicate minerals and carbonatite at 25 kbar and application to mantle metasomatism     

T. H. Green  J. Adam  S. H. Siel 《Mineralogy and Petrology》1992,46(3):179-184

Summary Experiments at 25 kbar and 1000°C, on a model trace element-enriched carbonatite-eridotite mix, produced augite + pargasite ± garnet ± dolomite coexisting with a carbonatite melt. Proton microprobe analysis of the phases showed that key trace elements (Rb, Ba, Sr, Nb, Ta, Zr, Y and REE) all partitioned strongly into the melt (with the exception of Y, Ho and Lu in garnet), verifying that carbonatite is potentially a highly effective metasomatizing agent. The data also indicate that carbonatitic metasomatism will impart higher Ba/Rb, Ba/Nb, Nb/Ta, Sr/Ta, La/Ta, and lower Zr/Y, with little change to Sr/Nb, in affected mantle.

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Spurenelementverteilung zwischen Silikatmineralen und Karbonatit bei 25 kbar: Anwendung für die Mantel-Metasomatose

Zusammenfassung Experimente mit einer Modell-mischung von Karbonatit-Peridotit, angereichert mit Spurenelementen, produzierten bei 25 kbar und 1000°C Augit + Pargasit ± Granat ±Dolomit coexistierend mit einer Karbonatitschmelze. Protonmikrosonden-Analyse der Phasen zeigte, dass alle Schlüsselspurenelemente (Rb, Ba, Sr, Nb, Ta, Zr, Y and REE) stark in der Schmelze angereichert werden (mit der Ausnahme von Y, Ho und Lu in Granat), was beweist, dass Karbonatit potentiell ein sehr effektives Agens für Metasomatose ist. Die Daten zeigen weiterhin, dass karbonatitische Metasomatose in betroffenen Mantel höhere Ba/Rb, Ba/Nb, Nb/Ta, Sr/Ta, La/Ta und niedrigere Zr/Y produziert, mit geringen Äderungen für Sr/Nb.

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With 1 Figure  相似文献   

Back-arc rifting in the Izu-Bonin Island Arc: Structural evolution of Hachijo and Aoga Shima Rifts   总被引：1，自引：0，他引：1  

Adam  Klaus Brian  Taylor Gregory F.  Moore Fumitoshi  Murakami Yukinobu  Okamura 《Island Arc》1992,1(1):16-31

Abstract Multi- and single-channel seismic profiles are used to investigate the structural evolution of back-arc rifting in the intra-oceanic Izu-Bonin Arc. Hachijo and Aoga Shima Rifts, located west of the Izu-Bonin frontal arc, are bounded along-strike by structural and volcanic highs west of Kurose Hole, North Aoga Shima Caldera and Myojin Sho arc volcanoes. Zig-zag and curvilinear faults subdivide the rifts longitudinally into an arc margin (AM), inner rift, outer rift and proto-remnant arc margin (PRA). Hachijo Rift is 65 km long and 20–40 km wide. Aoga Shima Rift is 70 km long and up to 45 km wide. Large-offset border fault zones, with convex and concave dip slopes and uplifted rift flanks, occur along the east (AM) side of the Hachijo Rift and along the west (PRA) side of the Aoga Shima Rift. No cross-rift structures are observed at the transfer zone between these two regions; differential strain may be accommodated by interdigitating rift-parallel faults rather than by strike- or oblique-slip faults. In the Aoga Shima Rift, a 12 km long flank uplift, facing the flank uplift of the PRA, extends northeast from beneath the Myojin Knoll Caldera. Fore-arc sedimentary sequences onlap this uplift creating an unconformity that constrains rift onset to ～1-2Ma. Estimates of extension (～3km) and inferred age suggest that these rifts are in the early syn-rift stage of back-arc formation. A two-stage evolution of early back-arc structural evolution is proposed: initially, half-graben form with synthetically faulted, structural rollovers (ramping side of the half-graben) dipping towards zig-zagging large-offset border fault zones. The half-graben asymmetry alternates sides along-strike. The present ‘full-graben’ stage is dominated by rift-parallel hanging wall collapse and by antithetic faulting that concentrates subsidence in an inner rift. Structurally controlled back-arc magmatism occurs within the rift and PRA during both stages. Significant complications to this simple model occur in the Aoga Shima Rift where the east-dipping half-graben dips away from the flank uplift along the PRA. A linear zone of weakness caused by the greater temperatures and crustal thickness along the arc volcanic line controls the initial locus of rifting. Rifts are better developed between the arc edifices; intrusions may be accommodating extensional strain adjacent to the arc volcanoes. Pre-existing structures have little influence on rift evolution; the rifts cut across large structural and volcanic highs west of the North Aoga Shima Caldera and Aoga Shima. Large, rift-elongate volcanic ridges, usually extruded within the most extended inner rift between arc volcanoes, may be the precursors of sea floor spreading. As extension continues, the fissure ridges may become spreading cells and propagate toward the ends of the rifts (adjacent to the arc volcanoes), eventually coalescing with those in adjacent rift basins to form a continuous spreading centre. Analysis of the rift fault patterns suggests an extension direction of N80°E ± 10° that is orthogonal to the trend of the active volcanic arc (N10°W). The zig-zag pattern of border faults may indicate orthorhombic fault formation in response to this extension. Elongation of arc volcanic constructs may also be developed along one set of the possible orthorhombic orientations. Border fault formation may modify the regional stress field locally within the rift basin resulting in the formation of rift-parallel faults and emplacement of rift-parallel volcanic ridges. The border faults dip 45–55° near the surface and the majority of the basin subsidence is accommodated by only a few of these faults. Distinct border fault reflections decreases dips to only 30° at 2.5 km below the sea floor (possibly flattening to near horizontal at 2.8 km although the overlying rollover geometry shows a deeper detachment) suggesting that these rifting structures may be detached at extremely shallow crustal levels.  相似文献   

Ethno‐Territoriality and Ethnic Conflict          下载免费PDF全文

Adam Moore 《Geographical review》2016,106(1):92-108

Ethno‐territoriality is an increasingly invoked term by those doing research on nationalism and ethnic conflict. Despite this, it has not been subject to detailed definitional and conceptual examination. This article develops a conceptual framework for thinking about ethno‐territoriality and ethnic conflict. It begins by briefly describing the relationship between territoriality, state sovereignty, and nationalist politics. I then provide a definition of ethno‐territoriality and outline a four‐part typology of the key elements of ethno‐territorial practice. Following this I discuss the role that ethno‐territoriality plays in the making of ethnic conflict.  相似文献