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41.
We present the finalized catalog of solar energetic proton events detected by the Wind/EPACT instrument over the period 1996?–?2016. Onset times, peak times, peak proton intensity and onset-to-peak proton fluence are evaluated for the two available energy channels, at about 25 and 50 MeV. We describe the procedure utilized to identify the proton events and to relate them to their solar origin (in terms of flares and coronal mass ejections). The statistical relationships between the energetic protons and their origin (linear and partial correlation analysis) are reported and discussed in view of earlier findings. Finally, the different trends found in the first 8 years of Solar Cycles 23 and 24 are discussed. 相似文献
42.
In 2007, the CNA Military Advisory Board (MAB), an expert panel composed of 11 retired admirals and generals from the United
States, identified climate change as a “threat multiplier” for instability in some of the most volatile regions of the world.
(CNA MAB National security and the threat of climate change
2007)The Department of Defense reached a similar conclusion in last year’s Quadrennial Defense Review–a legislatively mandated
analysis of the Defense Department’s strategy and priorities. This document frames the long-term course for policy decision-making
at the highest levels. The reports demonstrate that climate change and energy are now mainstream elements of national security
planning, and can be assessed within the frameworks used to evaluate other threats, risks, and responses. However, the exact
magnitude of the threat posed by climate change is difficult to calibrate in part because the language used by scientists
to predict uncertainty and the confidence levels of judgments is not sufficiently clear. The defense community has a vast
amount of experience exploring and dealing with uncertainty. Scientists trying to better describe the effects of climate change
may be able to draw lessons from the defense community’s approach to uncertainty including how to better communicate findings
to wide audiences including policy-makers. 相似文献
43.
Brent V. Alloway David J. Lowe David J. A. Barrell Rewi M. Newnham Peter C. Almond Paul C. Augustinus Nancy A. N. Bertler Lionel Carter Nicola J. Litchfield Matt S. McGlone Jamie Shulmeister Marcus J. Vandergoes Paul W. Williams NZ‐INTIMATE members 《第四纪科学杂志》2007,22(1):9-35
It is widely recognised that the acquisition of high‐resolution palaeoclimate records from southern mid‐latitude sites is essential for establishing a coherent picture of inter‐hemispheric climate change and for better understanding of the role of Antarctic climate dynamics in the global climate system. New Zealand is considered to be a sensitive monitor of climate change because it is one of a few sizeable landmasses in the Southern Hemisphere westerly circulation zone, a critical transition zone between subtropical and Antarctic influences. New Zealand has mountainous axial ranges that amplify the climate signals and, consequently, the environmental gradients are highly sensitive to subtle changes in atmospheric and oceanic conditions. Since 1995, INTIMATE has, through a series of international workshops, sought ways to improve procedures for establishing the precise ages of climate events, and to correlate them with high precision, for the last 30 000 calendar years. The NZ‐INTIMATE project commenced in late 2003, and has involved virtually the entire New Zealand palaeoclimate community. Its aim is to develop an event stratigraphy for the New Zealand region over the past 30 000 years, and to reconcile these events against the established climatostratigraphy of the last glacial cycle which has largely been developed from Northern Hemisphere records (e.g. Last Glacial Maximum (LGM), Termination I, Younger Dryas). An initial outcome of NZ‐INTIMATE has been the identification of a series of well‐dated, high‐resolution onshore and offshore proxy records from a variety of latitudes and elevations on a common calendar timescale from 30 000 cal. yr BP to the present day. High‐resolution records for the last glacial coldest period (LGCP) (including the LGM sensu stricto) and last glacial–interglacial transition (LGIT) from Auckland maars, Kaipo and Otamangakau wetlands on eastern and central North Island, marine core MD97‐2121 east of southern North Island, speleothems on northwest South Island, Okarito wetland on southwestern South Island, are presented. Discontinuous (fragmentary) records comprising compilations of glacial sequences, fluvial sequences, loess accumulation, and aeolian quartz accumulation in an andesitic terrain are described. Comparisons with ice‐core records from Antarctica (EPICA Dome C) and Greenland (GISP2) are discussed. A major advantage immediately evident from these records apart from the speleothem record, is that they are linked precisely by one or more tephra layers. Based on these New Zealand terrestrial and marine records, a reasonably coherent, regionally applicable, sequence of climatically linked stratigraphic events over the past 30 000 cal. yr is emerging. Three major climate events are recognised: (1) LGCP beginning at ca. 28 000 cal. yr BP, ending at Termination I, ca. 18 000 cal. yr BP, and including a warmer and more variable phase between ca. 27 000 and 21 000 cal. yr BP, (2) LGIT between ca. 18 000 and 11 600 cal. yr BP, including a Lateglacial warm period from ca. 14 800 to 13 500 cal. yr BP and a Lateglacial climate reversal between ca. 13 500 and 11 600 cal. yr BP, and (3) Holocene interglacial conditions, with two phases of greatest warmth between ca. 11 600 and 10 800 cal. yr BP and from ca. 6 800 to 6 500 cal. yr BP. Some key boundaries coincide with volcanic tephras. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
44.
Identifying slope processes over time and their imprint in soils of medium‐high mountains of Central Europe (the Karkonosze Mountains,Poland) 下载免费PDF全文
Jaroslaw Waroszewski Markus Egli Dagmar Brandová Marcus Christl Cezary Kabala Malgorzata Malkiewicz Jakub Kierczak Bartłomiej Glina Paweł Jezierski 《地球表面变化过程与地形》2018,43(6):1195-1212
Soils in mountainous areas are often polygenetic, developed in slope covers that relate to glacial and periglacial activities of the Pleistocene and Holocene and reflect climatic variations. Landscape development during the Holocene may have been influenced by erosion/solifluction that often started after the Holocene climatic optimum. To trace back soil evolution and its timing, we applied a multi‐methodological approach. This approach helped us to outline scenario of soil transformation. According to our results, some aeolian input must have occurred in the late Pleistocene. During that time and the early Holocene, the soils most likely had features of Cryosols or Leptosols. Physico‐chemical and mineralogical analyses have indicated that the material was denudated (between late Boreal to the Atlantic) from the ridge and upper‐slope positions forming a colluvium at mid‐slope positions. Later, during the Sub‐Boreal, mass wasting of the remains of silt material deposited at the end of the Pleistocene age on the ridge top seems to have occurred. In addition, the cool and moist conditions caused the deposition of a colluvium at the lower‐slope positions. The next phase was characterized by the transformation of Leptosols/Cambisols into Podzols at upper‐slope or shoulder positions and to Albic Cambisols at mid‐slope positions. During the Sub‐Boreal period, Stagnosols started to form at the lower part of the slope catena. Overall, the highest erosion rates were calculated at the upper‐slope position and the lowest rates at mid‐slope sites. Berylium‐10 (10Be) data showed that the Bs, BC/C were covered during the Holocene by a colluvium with a different geological composition which complicated the calculation of erosion or accumulation rates. The interpretation of erosion and accumulation rates in such multi‐layered materials may, therefore, be hampered. However, the multi‐methodological reconstruction we applied shed light on the soil and landscape evolution of the eastern Karkonosze Mountains. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
45.
AbstractSmall dams fragment river landscapes, disrupting channel connectivity and impacting water quality and quantity. Although they impound volumetrically less total water than large dams, the ubiquity of small dams suggests their cumulative impacts could be significant. Documenting the distribution and characteristics of small dams is necessary to understanding and mitigating their impacts. In this study, we compare datasets of small dams in Oregon, compile a new comprehensive dataset, and document geographic variations in small dam distributions between different ecoregions. We used Oregon Water Resources Department dam and Oregon Department of Fish and Wildlife fish passage barrier datasets to compare dam heights and contributing drainage areas between different ecoregions. Over 61% of Oregon’s land area is above one or more small dam. We highlight the location of Oregon’s small dams at valley margins, transition zones between flat plains and mountains, and areas of high population density. Given the hidden nature of small dams, evaluation of small dam impacts using public imagery is not effective. However, knowledge of small dam distributions given their association with landforms can aid in finding unrecorded dams, assessing approaches for evaluating their geomorphic impacts, and informing their management. 相似文献
46.
Florence Schubotz Julius S. Lipp Marcus Elvert Kai-Uwe Hinrichs 《Geochimica et cosmochimica acta》2011,75(16):4399-3574
Seepage of asphalt forms the basis of a cold seep system at 3000 m water depth at the Chapopote Knoll in the southern Gulf of Mexico. Anaerobic microbial communities are stimulated in the oil-impregnated sediments as evidenced by the presence of intact polar membrane lipids (IPLs) derived from archaea and Bacteria at depths up to 7 m below the seafloor. Detailed investigation of stable carbon isotope composition (δ13C) of alkyl and acyl moieties derived from a range of IPL precursors with distinct polar head groups resolved the complexity of carbon metabolisms and utilization of diverse carbon sources by uncultured microbial communities. In surface sediments most of the polar lipid-derived fatty acids with phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and diphosphatidylglycerol (DPG) head groups could be tentatively assigned to autotrophic sulfate-reducing bacteria, with a relatively small proportion involved in the anaerobic oxidation of methane. Derivatives of phosphatidyl-(N)-methylethanolamine (PME) were abundant and could be predominantly assigned to heterotrophic oil-degrading bacteria. Archaeal IPLs with phosphate-based hydroxyarchaeols and diglycosidic glyceroldibiphytanylglyceroltetraethers (GDGTs) were assigned to methanotrophic archaea of the ANME-2 and ANME-1 cluster, respectively, whereas δ13C values of phosphate-based archaeols and mixed phosphate-based and diglycosidic GDGTs point to methanogenic archaea. At a 7 m deep sulfate-methane transition zone that is linked to the upward movement of gas-laden petroleum, a distinct increase in abundance of archaeal IPLs such as phosphate-based hydroxyarchaeols and diglycosidic archaeol and GDGTs is observed; their δ13C values are consistent with their origin from both methanotrophic and methanogenic archaea. This study reveals previously hidden, highly complex patterns in the carbon-flow of versatile microbial communities involved in the degradation of heavy oil including hydrocarbon gases that would not have been evident from classical compound-specific isotope analyses of either bulk IPL or apolar lipid derivatives. 相似文献
47.
Marcus M. Key Jr. Kamil Zágoršek William P. Patterson 《International Journal of Earth Sciences》2013,102(1):305-318
Stable carbon and oxygen isotope values from single bryozoan colonies were used to reconstruct the paleoenvironments of the Early to Middle Miocene (Ottnangian to Badenian) sediments of the Central Paratethys. This approach utilizes a locally abundant allochem while avoiding matrix and multiple allochem contamination from bulk rock samples. Bryozoan colonies (and a few foraminifera and rock matrix samples) from 14 localities yielded 399 carbon and oxygen isotope values. Data from six of the localities (15 % of the total number of samples) were interpreted as having been diagenetically altered and were rejected. The remaining data indicate a primarily localized upwelling signal with lesser variation caused by global climatic and regional tectonic forcing of sea level, salinity, and temperature. Paleotemperatures were calculated to range from 12 to 21 °C. Despite potential taxonomic and diagenetic problems, bryozoan colonies are a powerful, underutilized source of paleoenvironmental carbon and oxygen isotope data. 相似文献
48.
Car routing solutions are omnipresent and solutions for pedestrians also exist.Furthermore,public or commercial buildings are getting bigger and the complexity of their internal structure has increased.Consequently,the need for indoor routing solutions has emerged.Some prototypes are available,but they still lack semantically-enriched modelling (e.g.,access constraints,labels,etc.) and are not suitable for providing user-adaptive length-optimal routing in complex buildings.Previous approaches consider simple rooms,concave rooms,and corridors,but important characteristics such as distinct areas in huge rooms and solid obstacles inside rooms are not considered at all,although such details can increase navigation accuracy.By formally defining a weighted indoor routing graph,it is possible to create a detailed and user-adaptive model for route computation.The defined graph also contains semantic information such as room labels,door accessibility constraints,etc.Furthermore,one-way paths inside buildings are considered,as well as three-dimensional building parts,e.g.,elevators or stairways.A hierarchical structure is also possible with the presented graph model. 相似文献
49.
Rebecca Hummels Marcus Dengler Peter Brandt Michael Schlundt 《Climate Dynamics》2014,43(11):3179-3199
Sea surface temperatures (SSTs) in the eastern tropical Atlantic are crucial for climate variability within the tropical belt. Despite this importance, state-of-the-art climate models show a large SST warm bias in this region. Knowledge about the seasonal mixed layer (ML) heat budget is a prerequisite for understanding SST mean state and its variability. Within this study all contributions to the seasonal ML heat budget are estimated at four locations within the Atlantic cold tongue (ACT) that are representative for the western (0°N, 23°W), central (0°N, 10°W) and eastern (0°N, 0°E) equatorial as well as the southern (10°S, 10°W) ACT. To estimate the contribution of the diapycnal heat flux due to turbulence an extensive data set of microstructure observations collected during ten research cruises between 2005 and 2012 is analyzed. The results for the equatorial ACT indicate that with the inclusion of the diapycnal heat flux the seasonal ML heat budget is balanced. Within the equatorial region, the diapycnal heat flux is essential for the development of the ACT. It dominates over all other cooling terms in the central and eastern equatorial ACT, while it is of similar size as the zonal advection in the western equatorial ACT. In contrast, the SST evolution in the southern ACT region can be explained entirely by air-sea heat fluxes. 相似文献
50.
Henning Tarp Jensen Marcus R. Keogh-Brown Richard D. Smith Zaid Chalabi Alan D. Dangour Mike Davies Phil Edwards Tara Garnett Moshe Givoni Ulla Griffiths Ian Hamilton James Jarrett Ian Roberts Paul Wilkinson James Woodcock Andy Haines 《Climatic change》2013,119(2):223-237
We employ a single-country dynamically-recursive Computable General Equilibrium model to make health-focussed macroeconomic assessments of three contingent UK Greenhouse Gas (GHG) mitigation strategies, designed to achieve 2030 emission targets as suggested by the UK Committee on Climate Change. In contrast to previous assessment studies, our main focus is on health co-benefits additional to those from reduced local air pollution. We employ a conservative cost-effectiveness methodology with a zero net cost threshold. Our urban transport strategy (with cleaner vehicles and increased active travel) brings important health co-benefits and is likely to be strongly cost-effective; our food and agriculture strategy (based on abatement technologies and reduction in livestock production) brings worthwhile health co-benefits, but is unlikely to eliminate net costs unless new technological measures are included; our household energy efficiency strategy is likely to breakeven only over the long term after the investment programme has ceased (beyond our 20 year time horizon). We conclude that UK policy makers will, most likely, have to adopt elements which involve initial net societal costs in order to achieve future emission targets and longer-term benefits from GHG reduction. Cost-effectiveness of GHG strategies is likely to require technological mitigation interventions and/or demand-constraining interventions with important health co-benefits and other efficiency-enhancing policies that promote internalization of externalities. Health co-benefits can play a crucial role in bringing down net costs, but our results also suggest the need for adopting holistic assessment methodologies which give proper consideration to welfare-improving health co-benefits with potentially negative economic repercussions (such as increased longevity). 相似文献