Abrupt Holocene climate change and potential response to solar forcing in western Canada

Several abrupt climate events during the Holocene, including the widely documented oscillation at 8.2 thousand years before present (ka), are attributed to changes in the North Atlantic thermohaline circulation. Additional mechanisms, such as interactions between atmospheric circulation, ice-sheet dynamics, and the influence of solar irradiance, also have been proposed to explain abrupt climatic events, but evidence remains elusive. This study presents evidence from multi-proxy analyses on the Holocene sediments of Eleanor Lake, interior British Columbia. Climatic inferences from our decadal-resolution record of biogenic silica (BSi) abundance are supported by changes in diatom and pollen assemblages from the same core and correlations with existing regional climate records. The BSi record reveals abrupt and persistent climatic shifts at 10.2, 9.3, and 8.5 ka, the latter two of which are coeval with major collapses of the Laurentide Ice Sheet. The record also reveals a short-term cooling at 8.2 ka that is distinct from the 8.5 ka event and similar in magnitude to several other late-Holocene coolings. BSi is correlated with solar-irradiance indices (r = 0.43–0.61), but the correlation is opposite in sign to that expected from direct solar forcing and weakens after 8 ka. Possible mechanisms causing the abrupt and persistent climate changes of the early Holocene include 1) sudden losses of ice and proglacial lake extent, causing a shift in the meridional structure of atmospheric circulation, 2) a possible link between solar minima and El Niño-like conditions that are correlated with warm spring temperature in interior British Columbia, and 3) the influence of solar irradiance variability on the position of the polar jet, possibly via effects on the strength of the glacial anticyclone.     

National-level factors affecting planned,public adaptation to health impacts of climate change

Our understanding of whether adaptive capacity on a national level is being translated into adaptation policies, programs, and projects is limited. Focusing on health adaptation in Annex I Parties to the UNFCCC, we examine whether statistically significant relationships exist between regulatory, institutional, financial, and normative aspects of national-level adaptive capacity and systematically measured adaptation. Specifically, we (i) quantify adaptation actions in Annex I nations, (ii) identify potential factors that might impact progress on adaptation and select measures for these factors, and (iii) calculate statistical relationships between factors and adaptation actions across countries. Statistically significant relationships are found between progress on adaptation and engagement in international environmental governance, national environmental governance, perception of corruption in the public sector, population size, and national wealth, as well as between responsiveness to health vulnerabilities, population size and national wealth. This analysis contributes two key early empirical findings to the growing literature concerning factors facilitating or constraining adaptation. While country size and wealth are necessary for driving higher levels of adaptation, they may be insufficient in the absence of policy commitments to environmental governance. Furthermore, governance and/or incentive frameworks for environmental governance at the national level may be an important indicator of the strength of national commitments to addressing health impacts of climate change.     

瓜德鲁普统(Guadalupian)-乐平统(Lopingian)全球界线层型剖面和点(GSSP)

乐平统底界全球界线层型(GSSP)已经被确定在中国广西来宾县的蓬莱滩剖面,这一界线以牙形类化石Clarkina postbitteri postbitteri Mei&Wardlaw的首次出现为标志,位于蓬莱滩剖面的茅口组顶部来宾灰岩的6k层之底,层型剖面点位于C.postbitter hongshuiensis至C.dukouensis的演化谱系内,大致与阿布萨罗卡巨层序(Absaroka Megasequenses)的中部与上部之间的界线相当。层型剖面点位所在的来宾灰岩代表了一套界于茅口组和合山组之间的低水位沉积,在这一界线附近,类、腕足类、珊瑚类和菊石类等动物群均发生了重大更替;同时,δ13C值和87Sr/86Sr同位素比值也有一个明显的降低。从瓜德鲁普世晚期的磁性正常极性带向吴家坪早期反向极性带的转变也发生在这一界线附近,因此,这一界线可以很好地用于进行全球海陆相地层的对比。     

Predicting site-specific storm wave run-up

Natural Hazards - Storm wave run-up causes beach erosion, wave overtopping, and street flooding. Extreme runup estimates may be improved, relative to predictions from general empirical formulae...     

The age of the Lugar sill and a discussion of the Late-Carboniferous/Early-Permian sill complex of S.W. Scotland

The incremental heating ⁴⁰Ar/³⁹Ar method has been used to date a kaersutite separate from the main theralite-picrite unit of the Lugar sill. Ar-release spectra show discordance mainly due to the presence of excess Ar in alteration phases intimately associated with the primary kaersutite. Plateaus in the spectra allow an emplacement age of 288 ± 6 Ma (2γ) to be assigned to the sill. The results are used to discuss the age relations of the alkaline Permo-Carboniferous sill complex of southwest Scotland. It is concluded that these sills could have been emplaced over a shorter period of time than implied by the available conventional K/Ar data. The classification of the alkaline sills into kylite and teschenite types has little petrogenetic significance.     

The Morpheus ultramodular autonomous underwater vehicle

The Advanced Marine Systems Lab at Florida Atlantic University has developed a new ultramodular plastic mini autonomous underwater vehicle (AUV), called the Morpheus, for littoral military and coastal oceanographic sampling, survey, and mapping. The name Morpheus was chosen because the Greek god Morpheus could change shape or "morph." The higher degree of modularity of the Morpheus AUV allows it to "morph" or change its size and components for different applications. This vehicle is composed of modular injection-molded plastic pressure vessels and a cabling system that allow the modules to be rearranged without rewiring bulkheads. The plastic pressure vessels are inexpensive, inherently mass-producible, extremely corrosion-resistant, and have low magnetic signatures. The pressure vessels are small but are sized to fit most standard electronic board standards. The mini AUV can be anywhere from 4 to 10 ft in length, depending on its mission. The vehicle architecture is an adaptation of the Ocean Explorer AUV system and uses an ANSI 709.1 (LonTalk) distributed control network for connecting all sensors and actuator subsystems as smart nodes. The modularity in containers, control, and power makes this vehicle rapidly reconfigurable and easy to repair or upgrade. This paper will present details of the motivation, design, and construction of the new mini AUV. The Morpheus was deployed during the summer of 2000 in field exercises for very shallow and shallow water mine counter measures. Some results from these tests will be presented     

THE DEL RIO ATAXITE,TEXAS

Del Rio is a new ataxite from Texas that is not related to either Monahans or Nordheim, the only previously known ataxites from Texas. Del Rio has a nickel content of approximately 12.9 weight percent, apparently has been shocked prior to its fall, and contains minor inclusions of daubreelite, schreibersite and troilite.     

Wideband monopulse sonar performance: cylindrical target simulationusing an acoustic scattering center model

A time-domain simulation that lends itself to the study of complex ocean environments, including complex seafloor shapes and suspended objects, has been developed. This simulation is used to study the response of a monopulse sonar to the presence of rigid cylinders near the seafloor. An acoustic-scattering-center model is developed to represent the cylinders, and several examples are presented and discussed     

Structure-composition relations and Raman spectroscopy of high-pressure sodium silicates

?-Na₂Si₂O₅, ζ-Na₂Si₂O₅, Na₂Si[Si₂O₇], and Na₆Si₃[Si₉O₂₇] have been synthesized using an MA6/8 superpress. Densification in high-pressure sodium silicates is effected largely by changes in packing. In the relaxed (1 bar) structures, cation polyhedra and thermal/displacement parameters are similar to those of low-pressure silicates, but the extra-framework cation positions are oversized. The two mixed ^[4]Si and ^[6]Si framework silicates of known structure (Na₂Si[Si₂O₇] and Na₆Si₃[Si₉O₂₇]) belong to the limited homologous series Na_2mSi_m[Si_n–mO_2n+m], with m<n. The structure-composition relationships of wadeite-type, A₂Ge₄O₉-type, and Na₆Si₃[Si₉O₂₇] silicates and germanates depend on T-O distance and size of the large extra-framework cation. Characteristic features of the SiO₄ tetrahedral units are present in micro-Raman spectra of mixed ^[4]Si and ^[6]Si framework silicates, but bands uniquely attributable to SiO₆ octahedra are weak or obscured. However, ^[6]Si has a profound indirect influence on the Raman spectra, resulting in intense and complex low-frequency bands, assigned to symmetric bending modes with coupled displacements at both bridging oxygens and nonbridging oxygens bonded to ^[6]Si, and a shift to higher frequency and reduction in intensity of the high-frequency bands assigned to symmetric ^[4]Si-O_nbr stretching vibrations. Raman spectroscopy does not appear to be a useful structural probe for small amounts of ^[6]Si in silicate glasses and melts.