Real-Time Flux Density Measurements of the 2011 Draconid Meteor Outburst

During the 2011 outburst of the Draconid meteor shower, members of the Video Meteor Network of the International Meteor Organization provided, for the first time, fully automated flux density measurements in the optical domain. The data set revealed a primary maximum at 20:09 UT ± 5 min on 8 October 2011 (195.036° solar longitude) with an equivalent meteoroid flux density of (118 ± 10) × 10/km/h at a meteor limiting magnitude of +6.5, which is thought to be caused by the 1900 dust trail. We also find that the outburst had a full width at half maximum of 80 min, a mean radiant position of α = 262.2°, δ = +56.2° (±1.3°) and geocentric velocity of v = 17.4 km/s (±0.5 km/s). Finally, our data set appears to be consistent with a small sub-maximum at 19:34 UT ±7 min (195.036° solar longitude) which has earlier been reported by radio observations and may be attributed to the 1907 dust trail. We plan to implement automated real-time flux density measurements for all known meteor showers on a regular basis soon.Peer reviewedFinal Accepted Versio

Проектирование системы электроснабжения электротехнического завода

Проводя исследование, на основе исходных данных, произведен выбор метода расчета, осуществился расчет электрических нагрузок завода и рассматриваемого цеха, подбор электроприемников и их проверка в зависимости от режима работы. Итогом исследования является, спроектированная конкретная модель электроснабжения промышленного предприятия, показана безопасность для окружающей среды и экономическая целесообразность.Carrying out the research, based on the initial data, the choice of the calculation method was made, the calculation of the electrical loads of the plant and the shop in question, the selection of electrical receivers and their verification, depending on the operating mode, were carried out. The result of the research is, the projected specific model of power supply of an industrial enterprise, shows the safety for the environment and the economic feasibility

Impacts of different climate change regimes and extreme climatic events on an alpine meadow community

Climate variability is expected to increase in future but there exist very few experimental studies that apply different warming regimes on plant communities over several years. We studied an alpine meadow community under three warming regimes over three years. Treatments consisted of (a) a constant level of warming with open-top chambers (ca. 1.9 °C above ambient), (b) yearly stepwise increases in warming (increases of ca. 1.0, 1.9 and 3.5 °C), and (c) pulse warming, a single first-year pulse event of warming (increase of ca. 3.5 °C). Pulse warming and stepwise warming was hypothesised to cause distinct first-year and third-year effects, respectively. We found support for both hypotheses; however, the responses varied among measurement levels (whole community, canopy, bottom layer, and plant functional groups), treatments, and time. Our study revealed complex responses of the alpine plant community to the different experimentally imposed climate warming regimes. Plant cover, height and biomass frequently responded distinctly to the constant level of warming, the stepwise increase in warming and the extreme pulse-warming event. Notably, we found that stepwise warming had an accumulating effect on biomass, the responses to the different warming regimes varied among functional groups, and the short-term perturbations had negative effect on species richness and diversityNFR grant (B-AA/BU 08424) to UM

Community and species-specific responses of plant traits to 23 years of experimental warming across subarctic tundra plant communities

To improve understanding of how global warming may affect competitive interactions among plants, information on the responses of plant functional traits across species to long-term warming is needed. Here we report the effect of 23 years of experimental warming on plant traits across four different alpine subarctic plant communities: tussock tundra, Dryas heath, dry heath and wet meadow. Open-top chambers (OTCs) were used to passively warm the vegetation by 1.5–3 °C. Changes in leaf width, leaf length and plant height of 22 vascular plant species were measured. Long-term warming significantly affected all plant traits. Overall, plant species were taller, with longer and wider leaves, compared with control plots, indicating an increase in biomass in warmed plots, with 13 species having significant increases in at least one trait and only three species having negative responses. The response varied among species and plant community in which the species was sampled, indicating community-warming interactions. Thus, plant trait responses are both species- and community-specific. Importantly, we show that there is likely to be great variation between plant species in their ability to maintain positive growth responses over the longer term, which might cause shifts in their relative competitive ability.Scopu

The Caledonian mountains. Northern Europe, and their changing ecosystems

With the exception of solar conditions, the climate of the Caledonian Mountains, Northern Europe, is influenced more by the nearness to the Atlantic Ocean and the Gulf Stream than by altitude and latitude. The length of the photoperiod during the growing season increases with latitude, although the total solar influx decreases. Heaths composed of species with a boreal distribution are particularly characteristic at low altitudes and latitudes, whereas species with an arctic and arctic-alpine distribution dominate at high altitudes and latitudes. Periodic events in the population dynamics of certain plant and animal species distinguish the ecosystems at high latitudes from those at low latitude. The effects of global change are likely to become most pronounced in the north since the rate at which the ultraviolet-B (UV-B) absorbing ozone layer is being reduced and the increase in concentration of «greenhouse gases» in the atmosphere are both higher in the arctic than in regions further south. Changes in the ecosystems due to increased direct human impacts are also likely to occur in some areas.[fr] À l'exception des conditions solaires, le climat des montagnes dites «Caledonian», au Nord de l'Europe, est beaucoup plus influencé par la proximité de l'Océan Atlantique et le Goulf Stream que par l'altitude ou la latitude. La durée de la photopériode pendant la saison de végétation augmente avec la latitude, tandis que la radiation solaire total s'abaisse. À des altitudes et latitudes basses, les landes riches en espèces à distribution boréale deviennent caractéristiques, tandis que les espèces arctiques et artico-alpines dominent dans les hautes altitudes ou latitudes. Des événements périodiques dans la dynamique de la population de certains animaux ou plantes peuvent distinguer les écosystèmes des hautes latitudes de ceux de basse latitude. Les effets du changement climatique global seraient bien sûr plus prononcés au nord, car d'une part le taux d'absortion de Vultraviolet-B (UV-B) par la couche d'ozone devient plus bas et d'autre part la concentration de gaz à effet de serre est plus forte dans les régions arctiques que plus au sud. De plus, dans certaines régions, il y a de changements dans les écosystèmes dûs à un impact direct croissant des activités humaines. [es] Condiciones solares aparte, el clima de las montañas caledonianas, situadas en el N de Europa, viene condicionado por la cercanía del Océano Atlántico y la corriente del Golfo, más que por la latitud y la altitud. Es sabido que la duración del fotoperíodo en el período de crecimiento vegetativo se incrementa con la latitud, aunque el flujo total solar descienda. Los brezales en cuya composición entran especies de distribución boreal son muy característicos de las bajas altitudes y latitudes. Ahora bien, las perturbaciones periódicas que tienen lugar en la dinámica poblacional de ciertas plantas o animales distinguen los ecosistemas de latitudes elevadas de los que están situados a baja latitud. Sin duda, los efectos del cambio global serán más intensos en el Norte, por cuanto la tasa de absorción de rayos ultravioleta B (UV-B) por parte de la capa de ozono se aminora y el incremento de la concentración de los «gases-invernadero» es consecuentemente mayor en el Ártico que en las zonas más meridionales. Además, en los ecosistemas también se están notando cambios por causa de los crecientes impactos directos de las actividades humanas en ciertas áreas

Meteor light curves: the relevant parameters

We investigate a uniform sample of 113 light curves (LCs) of meteors collected at the Wise Observatory in November 2002 while observing the Leonid meteor shower. We use previously defined descriptors such as the skewness F and a recently defined pointedness parameter along with a number of other measurable or derived quantities to explore the parameter space in search of meaningful LC descriptors. We make extensive use of statistical techniques to reveal links among the variables and to understand their relative importance. In particular, we show that meteors with long-duration trails rise slowly to their maximal brightness and also decay slowly from there while showing milder flaring than other meteors. Early skewed LCs show a fast rise to the peak. We show that the duration of te luminous phase of the meteor is th emost important variable differentiating among the 2002 LCs. The skewness parameter F appears only as the 2nd or 3rd in explaining the LC variance. We suggest that the pointedness parameter P could possibly be useful to discriminate among meteors from different showers, or to compare observations and model predictions.Comment: 10 pages (2 figures) in press with MNRA

Effects of Warming on Shrub Abundance and Chemistry Drive Ecosystem-Level Changes in a Forest-Tundra Ecotone

Tundra vegetation is responding rapidly to on-going climate warming. The changes in plant abundance and chemistry might have cascading effects on tundra food webs, but an integrated understanding of how the responses vary between habitats and across environmental gradients is lacking. We assessed responses in plant abundance and plant chemistry to warmer climate, both at species and community levels, in two different habitats. We used a long-term and multisite warming (OTC) experiment in the Scandinavian forest–tundra ecotone to investigate (i) changes in plant community composition and (ii) responses in foliar nitrogen, phosphorus, and carbon-based secondary compound concentrations in two dominant evergreen dwarf-shrubs (Empetrum hermaphroditum and Vaccinium vitis-idaea) and two deciduous shrubs (Vaccinium myrtillus and Betula nana). We found that initial plant community composition, and the functional traits of these plants, will determine the responsiveness of the community composition, and thus community traits, to experimental warming. Although changes in plant chemistry within species were minor, alterations in plant community composition drive changes in community-level nutrient concentrations. In view of projected climate change, our results suggest that plant abundance will increase in the future, but nutrient concentrations in the tundra field layer vegetation will decrease. These effects are large enough to have knock-on consequences for major ecosystem processes like herbivory and nutrient cycling. The reduced food quality could lead to weaker trophic cascades and weaker top down control of plant community biomass and composition in the future. However, the opposite effects in forest indicate that these changes might be obscured by advancing treeline forests

The challenge to detect and attribute effects of climate change on human and natural systems

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Climatic Change 121 (2013): 381-395, doi:10.1007/s10584-013-0873-6.Anthropogenic climate change has triggered impacts on natural and human systems world-wide, yet the formal scientific method of detection and attribution has been only insufficiently described. Detection and attribution of impacts of climate change is a fundamentally cross-disciplinary issue, involving concepts, terms, and standards spanning the varied requirements of the various disciplines. Key problems for current assessments include the limited availability of long-term observations, the limited knowledge on processes and mechanisms involved in changing environmental systems, and the widely different concepts applied in the scientific literature. In order to facilitate current and future assessments, this paper describes the current conceptual framework of the field and outlines a number of conceptual challenges. Based on this, it proposes workable cross-disciplinary definitions, concepts, and standards. The paper is specifically intended to serve as a baseline for continued development of a consistent cross-disciplinary framework that will facilitate integrated assessment of the detection and attribution of climate change impacts.Modeling Program of the Office of Biological and Environmental Research in the Department of Energy Office of Science under contract number DE-AC02-05CH11231. GH was supported by a grant from the German Ministry for Education and Research

Dominance hierarchies, diversity and species richness of vascular plants in an alpine meadow: contrasting short and medium term responses to simulated global change

We studied the impact of simulated global change on a high alpine meadow plant community. Specifically, we examined whether short-term (5 years) responses are good predictors for medium-term (7 years) changes in the system by applying a factorial warming and nutrient manipulation to 20 plots in Latnjajaure, subarctic Sweden. Seven years of experimental warming and nutrient enhancement caused dramatic shifts in dominance hierarchies in response to the nutrient and the combined warming and nutrient enhancement treatments. Dominance hierarchies in the meadow moved from a community being dominated by cushion plants, deciduous, and evergreen shrubs to a community being dominated by grasses, sedges, and forbs. Short-term responses were shown to be inconsistent in their ability to predict medium-term responses for most functional groups, however, grasses showed a consistent and very substantial increase in response to nutrient addition over the seven years. The non-linear responses over time point out the importance of longer-term studies with repeated measurements to be able to better predict future changes. Forecasted changes to temperature and nutrient availability have implications for trophic interactions, and may ultimately influence the access to and palatability of the forage for grazers. Depending on what anthropogenic change will be most pronounced in the future (increase in nutrient deposits, warming, or a combination of them both), different shifts in community dominance hierarchies may occur. Generally, this study supports the productivity–diversity relationship found across arctic habitats, with community diversity peaking in mid-productivity systems and degrading as nutrient availability increases further. This is likely due the increasing competition in plant–plant interactions and the shifting dominance structure with grasses taking over the experimental plots, suggesting that global change could have high costs to biodiversity in the Arctic