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111.
Galateia Terti Isabelle Ruin Sandrine Anquetin Jonathan J. Gourley 《Natural Hazards》2015,79(3):1481-1497
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Decadal‐Scale Changes of the Ödenwinkelkees,Central Austria,Suggest Increasing Control of Topography and Evolution Towards Steady State 下载免费PDF全文
Jonathan L. Carrivick Katie Berry Martin Geilhausen William H.M. James Christopher Williams Lee E. Brown David M. Rippin Steve J. Carver 《Geografiska Annaler: Series A, Physical Geography》2015,97(3):543-562
Small mountain glaciers have short mass balance response times to climate change and are consequently very important for short‐term contributions to sea level. However, a distinct research and knowledge gap exists between (1) wider regional studies that produce overview patterns and trends in glacier changes, and (2) in situ local scale studies that emphasise spatial heterogeneity and complexity in glacier responses to climate. This study of a small glacier in central Austria presents a spatiotemporally detailed analysis of changes in glacier geometry and changes in glaciological behaviour. It integrates geomorphological surveys, historical maps, aerial photographs, airborne LiDAR data, ground‐based differential global positioning surveys and Ground Penetrating Radar surveys to produce three‐dimensional glacier geometry at 13 time increments spanning from 1850 to 2013. Glacier length, area and volume parameters all generally showed reductions with time. The glacier equilibrium line altitude increased by 90 m between 1850 and 2008. Calculations of the mean bed shear stress rapidly approaching less than 100 kPA, of the volume–area ratio fast approaching 1.458, and comparison of the geometric reconstructions with a 1D theoretical model could together be interpreted to suggest evolution of the glacier geometry towards steady state. If the present linear trend in declining ice volume continues, then the Ödenwinkelkees will disappear by the year 2040, but we conceptualise that non‐linear effects of bed overdeepenings on ice dynamics, of supraglacial debris cover on the surface energy balance, and of local topographically driven controls, namely wind‐redistributed snow deposition, avalanching and solar shading, will become proportionally more important factors in the glacier net balance. 相似文献
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Julien?LeutholdEmail author Jonathan?D.?Blundy Richard?A.?Brooker 《Contributions to Mineralogy and Petrology》2015,169(2):12
The 176Lu–176Hf and 147Sm–143Nd decay systems are routinely used to determine garnet (Grt)–whole-rock (WR) ages; however, the 176Lu–176Hf age of garnet is typically older than the 147Sm–143Nd age determined from the same aliquots. Here we present experimental data for Lu3+ and Hf4+ diffusion in garnet as functions of temperature, pressure and oxygen fugacity and show that the diffusivity of Hf4+ in almandine/spessartine garnet is significantly slower than that of Lu3+. The diffusive closure temperature (T C) of Hf4+ is significantly higher than that of Nd3+, and although this property is partly responsible for the observed 176Lu–176Hf and 147Sm–143Nd Grt–WR age discrepancies, the difference between the T C-s of Lu3+ and Hf4+ could lead to apparent Grt–WR 176Lu–176Hf ages that are skewed from the age of Hf4+ closure in garnet. In addition, the slow diffusivity of Hf4+ indicates that the bulk of metamorphic garnets retain a substantial fraction of prograde radiogenic 176Hf throughout peak metamorphic conditions, a phenomenon that further complicates the interpretation of 176Lu–176Hf garnet ages and invalidates the use of analytical T C expressions. We argue that the diffusion of trivalent rare earth elements in garnet becomes much faster when their concentration level falls below a few hundred ppm, as in the experiments of Tirone et al. (Geochim Cosmochim Acta 69: 2385–2398, 2005), and further argue that this low-concentration mechanism is appropriate for modeling the susceptibility of 147Sm–143Nd garnet ages to diffusive resetting. 相似文献
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Kristie L. Ebi Elisabet Lindgren Jonathan E. Suk Jan C. Semenza 《Climatic change》2013,118(2):355-365
Climate change has the potential to increase the challenge of preventing and controlling outbreaks of infectious diseases. An adaptation assessment is an important aspect of designing and implementing policies and measures to avoid, prepare for, and effectively respond to infectious diseases outbreaks. The main steps in conducting an adaptation assessment include: 1) evaluating the effectiveness of policies and measures that address the burden of climate-sensitive infectious diseases; 2) identifying options to manage the health risks of current and projected climate change; 3) evaluating and prioritizing the options; 4) identifying human and financial resources needs, and possible barriers, constraints, and limits to implementation; and 5) developing monitoring and evaluation programs to ensure continued effectiveness of policies and measures in a changing climate. Optimally, relevant stakeholders are optimally included throughout the adaptation assessment. Although the process of conducting an assessment is similar across nations and regions, the context and content will vary depending on local circumstances, socioeconomic conditions, legal and regulatory frameworks, and other factors. The European Centers for Disease Prevention and Control developed guidelines for conducting assessments, with sufficient consistency to facilitate learning lessons across assessments. 相似文献
118.
Ken Kobayashi Jonathan Cirtain Amy R. Winebarger Kelly Korreck Leon Golub Robert W. Walsh Bart De Pontieu Craig DeForest Alan Title Sergey Kuzin Sabrina Savage Dyana Beabout Brent Beabout William Podgorski David Caldwell Kenneth McCracken Mark Ordway Henry Bergner Richard Gates Sean McKillop Peter Cheimets Simon Platt Nick Mitchell David Windt 《Solar physics》2014,289(11):4393-4412
The High-Resolution Coronal Imager (Hi-C) was flown on a NASA sounding rocket on 11 July 2012. The goal of the Hi-C mission was to obtain high-resolution (≈?0.3?–?0.4′′), high-cadence (≈?5 seconds) images of a solar active region to investigate the dynamics of solar coronal structures at small spatial scales. The instrument consists of a normal-incidence telescope with the optics coated with multilayers to reflect a narrow wavelength range around 19.3 nm (including the Fe xii 19.5-nm spectral line) and a 4096×4096 camera with a plate scale of 0.1′′?pixel?1. The target of the Hi-C rocket flight was Active Region 11520. Hi-C obtained 37 full-frame images and 86 partial-frame images during the rocket flight. Analysis of the Hi-C data indicates the corona is structured on scales smaller than currently resolved by existing satellite missions. 相似文献
119.
Ronan Higgins David Teyssier Colin Borys Jonathan Braine Claudia Comito Bertrand Delforge Frank Helmich Michael Olberg Volker Ossenkopf John Pearson Russell Shipman 《Experimental Astronomy》2014,37(2):433-452
The Heterodyne Instrument for the Far Infrared (HIFI) on board the Herschel Space Observatory is composed of a set of fourteen double sideband mixers. We discuss the general problem of the sideband ratio (SBR) determination and the impact of an imbalanced sideband ratio on the line calibration in double sideband heterodyne receivers. The HIFI SBR is determined from a combination of data taken during pre-launch gas cell tests and in-flight. The results and some of the calibration artefacts discovered in the gas cell test data are presented here along with some examples of how these effects appear in science data taken in orbit. 相似文献
120.
Jonathan A. Tedds Peter W. J. L. Brand Michael G. Burton Antonio Chrysostomou Amadeu J. L. Fernandes 《Astrophysics and Space Science》1995,224(1-2):139-142
Recent near-IR imaging of the Orion molecular cloud has revealed a complex of dense bullets, visible as [FeII] emitting HH-objects at the tips of H2 wakes, ejected explosively from the cloud core. Having resolved individual bow-shock structures for the first time in this bright source, we have observed [FeII] 1.644µm velocity profiles of selected bullets and H2 1-0 S(1), 2.122µm velocity profiles for a series of positions along and across the corresponding bow-shock wakes. We present observed profiles for the bullet M42 HH1 and its associated wake and compare with theoretical bow-shock models. 相似文献