大兴安岭中南段中生代成矿物质的深部来源与背景

大兴安岭是我国北方一个重要的多金属成矿带。本文从成矿的物质来源和构造作用两方面讨论大兴安岭的成矿系统。Sr、Nd、O、Pb同位素的研究显示大兴安岭成矿物质的深部来源,大兴安岭晚中生代壳幔混熔花岗质岩石组成及其构造环境的研究,表明它们是在板内非造山的伸展环境下形成的A型花岗岩。与南岭花岗岩及其成矿作用的对比研究,将加深对大兴安岭中生代成矿特征的认识。深部构造特征也进一步印证了大兴安岭的成岩-成矿的背景。     

Summer temperature variability across four urban neighborhoods in Knoxville,Tennessee, USA

The urban heat island (UHI) is a well-documented effect of urbanization on local climate, identified by higher temperatures compared to surrounding areas, especially at night and during the warm season. The details of a UHI are city-specific, and microclimates may even exist within a given city. Thus, investigating the spatiotemporal variability of a city’s UHI is an ongoing and critical research need. We deploy ten weather stations across Knoxville, Tennessee, to analyze the city’s UHI and its differential impacts across urban neighborhoods: two each in four neighborhoods, one in more dense tree cover and one in less dense tree cover, and one each in downtown Knoxville and Ijams Nature Center that serve as control locations. Three months of temperature data (beginning 2 July 2014) are analyzed using paired-sample t tests and a three-way analysis of variance. Major findings include the following: (1) Within a given neighborhood, tree cover helps negate daytime heat (resulting in up to 1.19 ^°C lower maximum temperature), but does not have as large of an influence on minimum temperature; (2) largest temperature differences between neighborhoods occur during the day (0.38–1.16 ^°C difference), but larger differences between neighborhoods and the downtown control occur at night (1.04–1.88 ^°C difference); (3) presiding weather (i.e., air mass type) has a significant, consistent impact on the temperature in a given city, and lacks the differential impacts found at a larger-scale in previous studies; (4) distance from city center does not impact temperature as much as land use factors. This is a preliminary step towards informing local planning with a scientific understanding of how mitigation strategies may help minimize the UHI and reduce the effects of extreme weather on public health and well-being.     

Palaeoecology and taxonomy of Pentoxylales from the Albian of Antarctica

Reproductive pentoxylalean material from the Albian Triton Point Formation, Fossil Bluff Group of Alexander Island, Antarctica is the youngest record of this group globally. Leaves are referred to Taeniopteris daintreei McCoy, ovulate reproductive organs to Carnoconites cranwelli Harris, and stem material to Pentoxylon sp. Occurring in leaf litter layers on palaeosol surfaces the sedimentology suggests that pentoxylalean plants grew upon areas of the floodplain distal to the river channel, where they covered the forest floor in a similar habit to modern brambles. The forest floor was shared with Equisetales and liverworts, an abundance of ferns [Cladophlebis Brongniart, Gleichenites Goeppert, Phyllopteroides Medwell, Sphenopteris (Brongniart) Sternberg], as well as angiosperms. Bennettitales, Ginkgoites Seward and Nilssonia Brongniart were rare within these communities, as were coniferous trees.     

Variations in solar sub-surface rotation from GONG data 1995–1998

We have completed an analysis of the first 35 GONG Months (1 GM = 36 days) covering the last solar minimum and the rising phase of cycle 23. The mode parameters have been estimated from 33 time series, each of 3-GM duration, with centers spaced by 1 GM. We report on the temporal evolution of the rotational splitting coefficients up to 15th order. The coefficients do not correlate well with any surface magnetic flux measure yet considered, but we find small but significant trends in their temporal evolution. Inverting the coefficients for two-dimensional rotation information and looking at deviations from the mean produces a picture of a systematic zonal flow migrating towards lower latitudes during the rising phase of the cycle. This flow is probably associated with the torsional oscillation. Similar trends are seen in the 1986–1990 BBSO data.     

Public perceptions of rainfall change in India

People’s perceptions of changes in local weather patterns are an important precursor to proactive adaptation to climate change. In this paper, we consider public perceptions of changes in average rainfall in India, analyzing the relationship between perceptions and the instrumental record. Using data from a national sample survey, we find that local instrumental records of precipitation are a strong predictor of perceived declines in rainfall. Perceptions of decreasing rainfall were also associated with perceptions of changes in extreme weather events, such as decreasing frequency of floods and severe storms, increasing frequency of droughts, and decreasing predictability of the monsoon. Higher social vulnerability—including low perceived adaptive capacity and greater food and livelihood dependence on local weather—was also associated with perceptions of decreasing rainfall. While both urban and rural respondents were likely to perceive local changes in precipitation, we show that rural respondents in general were more sensitive to actual changes in precipitation. Individual perceptions of changes in local climate may play an important role in shaping vulnerability to global climate change, adaptive behavior, and support for adaptation and mitigation policies. Awareness of local climate change is therefore particularly important in regions where much of the population is highly exposed and sensitive to the impacts of climate change.     

Ice caps existed throughout the Lateglacial Interstadial in northern Scotland

We constrain, in detail, fluctuations of two former ice caps in NW Scotland with multibeam seabed surveys, geomorphological mapping and cosmogenic ¹⁰Be isotope analyses. We map a continuous sequence of 40 recessional moraines stretching from ～10 km offshore to the Wester Ross mountains. Surface‐exposure ages from boulders on moraine ridges in Assynt and the Summer Isles region show that substantial, dynamic, ice caps existed in NW Scotland between 13 and 14 ka BP. We interpret this as strong evidence that large active glaciers probably survived throughout the Lateglacial Interstadial, and that during the Older Dryas period (ca. 14 ka BP) ice caps in NW Scotland were thicker and considerably more extensive than in the subsequent Younger Dryas Stadial. By inference, we suggest that Lateglacial ice‐cap oscillations in Scotland reflect the complex interplay between changing temperature and precipitation regimes during this climatically unstable period (ca. 15–11 ka BP). © Natural Environment Research Council (NERC) copyright 2008. Reproduced with the permission of NERC. Published by John Wiley & Sons, Ltd.     

Power system considerations for undersea observatories

Power systems for undersea observatories combine ideas from terrestrial power systems and switching power supplies with experience from undersea cable systems. Basic system tradeoffs for various design decisions are explored in this paper. First, design questions including whether the power delivery should be alternating or direct current and a parallel or series network are examined. This introduces the question of maximum power delivery capability, which is explored in depth. A separate issue, the negative incremental resistance presented to the delivery system by the use of constant-voltage converters, is examined, and the resulting dynamics explored by simulation