Editorial comment: Simplicity     

Dennis Lindley 《Mathematical Geosciences》1997,29(2):183-184

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A multi-dimensional assessment of urban vulnerability to climate change in Sub-Saharan Africa     

Herslund  Lise Byskov  Jalayer  Fatemeh  Jean-Baptiste  Nathalie  J&#;rgensen  Gertrud  Kabisch  Sigrun  Kombe  Wilbard  Lindley  Sarah  Nyed  Patrik Karlsson  Pauleit  Stephan  Printz  Andreas  Vedeld  Trond 《Natural Hazards》2015,82(2):149-172

In this paper, we develop and apply a multi-dimensional vulnerability assessment framework for understanding the impacts of climate change-induced hazards in Sub-Saharan African cities. The research was carried out within the European/African FP7 project CLimate change and Urban Vulnerability in Africa, which investigated climate change-induced risks, assessed vulnerability and proposed policy initiatives in five African cities. Dar es Salaam (Tanzania) was used as a main case with a particular focus on urban flooding. The multi-dimensional assessment covered the physical, institutional, attitudinal and asset factors influencing urban vulnerability. Multiple methods were applied to cover the full range of vulnerabilities and to identify potential response strategies, including: model-based forecasts, spatial analyses, document studies, interviews and stakeholder workshops. We demonstrate the potential of the approach to assessing several dimensions of vulnerability and illustrate the complexity of urban vulnerability at different scales: households (e.g., lacking assets); communities (e.g., situated in low-lying areas, lacking urban services and green areas); and entire cities (e.g., facing encroachment on green and flood-prone land). Scenario modeling suggests that vulnerability will continue to increase strongly due to the expected loss of agricultural land at the urban fringes and loss of green space within the city. However, weak institutional commitment and capacity limit the potential for strategic coordination and action. To better adapt to urban flooding and thereby reduce vulnerability and build resilience, we suggest working across dimensions and scales, integrating climate change issues in city-level plans and strategies and enabling local actions to initiate a ‘learning-by-doing’ process of adaptation.

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Scientific exploration of near‐Earth objects via the Orion Crew Exploration Vehicle     

Paul A. Abell  David J. Korsmeyer  Rob R. Landis  Thomas D. Jones  Daniel R. Adamo  David D. Morrison  Lawrence G. Lemke  Andrew A. Gonzales  Robert Gershman  Theodore H. Sweetser  Lindley L. Johnson  Ed Lu 《Meteoritics & planetary science》2009,44(12):1825-1836

Abstract— A study in late 2006 was sponsored by the Advanced Projects Office within NASA's Constellation Program to examine the feasibility of sending the Orion Crew Exploration Vehicle (CEV) to a near‐Earth object (NEO). The ideal mission profile would involve two or three astronauts on a 90 to 180 day flight, which would include a 7 to 14 day stay for proximity operations at the target NEO. This mission would be the first human expedition to an interplanetary body beyond the Earth‐Moon system and would prove useful for testing technologies required for human missions to Mars and other solar system destinations. Piloted missions to NEOs using the CEV would undoubtedly provide a great deal of technical and engineering data on spacecraft operations for future human space exploration while conducting in‐depth scientific investigations of these primitive objects. The main scientific advantage of sending piloted missions to NEOs would be the flexibility of the crew to perform tasks and to adapt to situations in real time. A crewed vehicle would be able to test several different sample collection techniques and target specific areas of interest via extra‐vehicular activities (EVAs) more efficiently than robotic spacecraft. Such capabilities greatly enhance the scientific return from these missions to NEOs, destinations vital to understanding the evolution and thermal histories of primitive bodies during the formation of the early solar system. Data collected from these missions would help constrain the suite of materials possibly delivered to the early Earth, and would identify potential source regions from which NEOs originate. In addition, the resulting scientific investigations would refine designs for future extraterrestrial resource extraction and utilization, and assist in the development of hazard mitigation techniques for planetary defense.  相似文献   

Mid Pleistocene climate instability in the subtropical northwestern Atlantic     

K. Billups  C. Lindley  J. Fisler  P. Martin 《Global and Planetary Change》2006,54(3-4):251-262

We present Globigerinoides ruber, G. sacculifer and Neogloboquadrina dutertrei oxygen isotope records from northwestern subtropical Atlantic Site 1058 spanning the mid Pleistocene ( 600 to 400 ka). The high temporal resolution of these records ( 800 yr) allows us to compare millennial-scale climate signals during one of the most extreme glacial periods of the Pleistocene (Marine Isotope Stage (MIS) 12) to an earlier, less extreme glacial (MIS 14), as well as to two full interglacial intervals (MIS 13 and MIS 15). We observe excellent agreement in the timing and amplitude of variations between the surface-most dwelling species G. ruber and Northern Hemisphere insolation during the two interglacial periods. There is some expression of Northern Hemisphere insolation during glacial MIS 14; however, during the more extreme glacial MIS 12 Northern Hemisphere insolation patterns are not apparent in any of the planktonic foraminiferal δ¹⁸O records. Insolation remains relatively high, but δ¹⁸O values increase toward the characteristic δ¹⁸O maximum of MIS 12 in all three of the records. On the millennial-scale, all three species display their highest amplitude δ¹⁸O variations (with a period between 4–6 kyr) during glacial MIS 12. Suborbital-scale variability is also statistically significant during glacial MIS 14, but the amplitude is smaller. These results support hypotheses linking millennial-scale climate fluctuations to the extent of continental glaciation. We propose that the relatively high degree of sea surface instability during one of the most extreme glacial periods of the Pleistocene arises from the competing effects of strong atmospheric winds related to the presence of a large ice sheet to the north and persistently high incident solar radiation during this interval of time.  相似文献   

Fine-scale spatial temperature patterns across a UK conurbation     

Claire L. Smith  A. Webb  G. J. Levermore  S. J. Lindley  K. Beswick 《Climatic change》2011,109(3-4):269-286

The public health implications of a warming urban environment mean that appropriate action by planners, designers and health workers will be necessary to minimise risk under future climate scenarios. Data at an appropriate spatial scale are required by user groups in order to identify key areas of vulnerability. Thermal mapping of a UK urban conurbation was carried out during the summers of 2007 and 2008 with the aim of providing high spatial resolution temperature data. The air temperature results showed an average daytime (night time) urban?Crural thermal contrast of 3°C (5°C) on summer days (nights) with ideal urban heat island (UHI) conditions. The intensity of the daytime surface temperature heat island was found to exceed 10°C. The measured data were used to derive an empirical model of spatial temperature patterns based upon characteristics of land use, distance from urban centre and building geometry. This model can be used to provide sub-kilometre resolution temperature data which are required by decision makers and can provide a mechanism for downscaling climate model output.  相似文献   

Stratigraphy, palaeomagnetism and age of volcanics in the upper regions of ÞJórsárdalur valley, central southern Iceland     

LEÓ KRISTJÁNSSON  ROBERT A. DUNCAN  ÁGÚST GUÐMUNDSSON 《Boreas: An International Journal of Quaternary Research》1998,27(1):1-13

The 'Hreppar Formation' of southern Iceland is a succession mostly composed of basalt lavas and clastic material, with a slight anticlinal structure. It may represent a crustal fragment left in place by eastwards movement of the active spreading zone during the past 2–3 Ma. Evidence of several cycles of alternating glacial-interglacial conditions is seen in this succession. The first systematic stratigraphic study within the succession which is combined with K-Ar age determinations and laboratory palaeomagnetic measurements on oriented cores has yielded encouraging results. The age determinations confirm earlier estimates by Icelandic geologists on the age range spanned by the Hreppar succession. Units from the Jaramillo geomagnetic subchron are present in its upper part, and at least one polarity reversal event in the lower Matuyama chron is also recorded.  相似文献   

Nature, origin and classification of peritidal tepee structures and related breccias   总被引：4，自引：0，他引：4  

RICCARDO L. A. M. ASSERETO  CHRISTOPHER G. ST C.  KENDALL† 《Sedimentology》1977,24(2):153-210

Distinctive peritidal tepee antiform structures, buckled margins of saucer-like megapolygons are common in marine vadose fenestral and pisolitic limestones and/or dolomites of carbonate platform sequences and occur in intertidal and supratidal carbonates ranging in age from Silurian to Holocene. These megapolygons commonly form and are sometimes truncated before the deposition of the next sedimentary layer. The megapolygons result from the expansion of surface sediments by as much as 15%. The expansion is caused by the following continuously repeated sequence of processes: (1) Desiccation and thermal contraction causing small fractures; (2) phases of wetting causing enlargement of fractures; (3) phases of crystallization of calcium carbonate and other minerals causing the enlargement, fill and cementation of the fractures. Precipitation is from brines and meteoric waters; (4) hydration of minerals, thermal expansion, breaking waves and faulting may add to this disruption. The development of the tepee fabric can be traced from an initially cemented subaerial fenestral crust, exhibiting expansion and compressional structures, to a completely disrupted and brecciated sediment riddled by a labyrinth of fractures and solution cavities. These spaces are filled by numerous phases of internal marine and fresh-water cement and sediment, the latter containing penecontemporaneous or younger marine faunas. Peritidal tepees are useful tools for geologic reconstruction and provide evidence of subaerial exposure; a tropical to subtropical climate; and back-beach or back-barrier deposition. Proper identification of tepees is of economic importance, because they provide good early porosity and permeability for petroleum entrapment and a site for mineralization. Aesthetically, tepee rocks are a fine kaleidoscopic decorative stone.  相似文献   

A wind-tunnel investigation of the wind speed and turbulence characteristics close to the ground over various escarpment shapes   总被引：1，自引：1，他引：0  

A. J. Bowen  D. Lindley 《Boundary-Layer Meteorology》1977,12(3):259-271

A wind-tunnel investigation of the wind flow over two-dimensional forward-facing escarpments is reported as part of a continuing research programme into the effects of local topography on the wind flow close to the ground. Four sharp-edged escarpments with their slopes varying between a cliff and a 4:1 gradient, were placed normal to a simulated neutrally-stable rural boundary layer which was modelled to a scale of 1:300. The resulting flows close to the surfaces of the escarpments were measured with a hot-wire anemometer. The modifications to the mean wind speed, turbulence intensity and energy spectra over the escarpments are described. The results indicate the extent and magnitude of the modification to the flow and suggest that significant changes in turbulence characteristics only occur in the wake region close behind the crest, where a shift of energy to higher frequencies is evident.  相似文献   

A wind tunnel boundary-layer simulation of wind flow over complex terrain: Effect of terrain and model construction     

D. Neal  D. C. Stevenson  D. Lindley 《Boundary-Layer Meteorology》1981,21(3):271-293

The report presents the results of a wind-tunnel study of the flow of the natural wind over complex terrain. A 1:4000 undistorted scale model of Gebbies Pass in the South Island of New Zealand was prepared and tested in the boundary-layer wind tunnel in the Department of Mechanical Engineering at the University of Canterbury.Three forms of construction, viz., terraced, contoured and roughness-added, were compared. Velocity and turbulence profiles, Reynolds stresses and spectra were measured, and correlation of results between different types of construction was calculated. The terraced form was much simpler to construct but was found to be unsatisfactory. The correlation between the contoured and roughness-added models was as high as 0.94, although the roughness-added model made a significant difference to the results in the lower 20%; of the boundary layer. The results of these tests will be compared with results from the field in a future report.  相似文献   

Subsolidus Phase Relations in the System MgO--SiO2--Gr--O in Equilibrium with Metallic Cr, and their Significance for the Petrochemistry of Chromium     

LI  JIAN-PING; O'NEIL  HUGH ST C.; SEIFERT  FRIEDRICH 《Journal of Petrology》1995,36(1):107-132

Subsolidus phase relations have been determined in the systemsSiO₂-Cr-0 and MgO-SiO₂-Cr-O in equilibrium with metallic Cr,at 1100–1500C and 0–288 kbar. There are no ternaryphases in the SiO₂-Cr-O system at these conditions, ie. onlythe assemblage eskolaite + Cr-metal + SiO₂ is found. However,in the MgO-containing system, extensive substitution of Cr²⁺for Mg is observed in (Mg,Cr²⁺)₂SiO₄ olivine, (Mg,Cr²⁺)₂Si₂O₆pyroxene, and (Mg,Cr²⁺)Cr³⁺₂0₄ spinel. Cr ³⁺ levels in olivineand pyroxene are below detection limits. The pyroxene is orthorhombicat monoclinic at higher . The structure of the spinels becomestetragonally distorted at is limited by the breakdown of olivine to pyroxene + spinel+ metal. This maximum amount increases strongly with increasingtemperature, reaching >0.2 at 1500C and 48 kbar. Increasing pressure reduces the maximum. Increasing temperature also increases the maximum amounts of Cr²⁺ which substitute intopyroxene and spinel, indicating that end-member Cr₂Si₂0₆ andCr₃O₄ may become stable above 1650C if melting does not intervene.Powder X-ray diffraction analysis of selected runs has beenused to extract molar volumes of the Mg-Cr²⁺ solid solutionsas a function of composition, which may be extrapolated to predictmolar volumes for Cr₂SiO₄ (olivine), Cr₂Si₂O₆ (ortho- and clino-pyroxene)and Cr₂O₄ (cubic spinel) of 477, 680 and 449 cm³, respectively.The experimental data have been fitted to a thermodynamic model,including free energies of formation for end member Cr₂SiO₄,Cr₂Si₂O₆ and Cr₃O₄. This model is then used to predict the amountsof Cr²⁺ which can be expected in olivine in equilibrium withCr-bearing spinel as a function of T, P and fo₂. This amountincreases strongly with temperature along standard T-fo₂ buffercurves, and is sufficient to explain the observed high Cr contentsof olivine from komatiites and diamond inclusions at reasonableterrestrial fo, values. The lower fo₂ of the lunar environmentresults in significant Cr²⁺ in olivine being stable to muchlower temperatures. The tendency for the oxidation state ofCr, and hence its geochemical properties, to change with temperaturerelative to other redox reactions makes it a potentially usefulmonitor of the temperatures of uppermantle processes, and isa significant factor in the differing styles of igneous differentiationin the Earth and Moon. Corresponding author  相似文献