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91.
Daniela ez
ov Marek Kapar Miloslav Müller Zbynk Sokol Vilibald Kakos David Hanslian Petr Peice 《Atmospheric Research》2005,77(1-4):354
The hydro-meteorological characteristics of the flood from August 2002, which affected a great part of the Czech territory, particularly the Vltava and Labe river basin, were compared with corresponding conditions during similar flood events in the summer seasons of 1997, 1890, 1897 and 1903. The comparison shows analogies in synoptic conditions and causal precipitation heights. The heaviest precipitation fell in the area of a considerable horizontal pressure gradient on the rearward side of the cyclone which advanced very slowly to the north-east across Central Europe and created conditions for the transport of moist air as well as for an organized long-term updraft enhanced in orographically exposed regions. The varying features of the individual events were based on the spatial–temporal distribution of causal precipitation and also on the very different saturation of the catchments. It was chiefly the extraordinary time concentration of precipitation together with the highest catchment saturation that made the flood in 2002 the most extreme.The extremeness of meteorological fields during two episodes in July 1997 was compared with two episodes in August 2002 with the aid of the reanalysis data from ECMWF. The first episode in 1997 and the second episode in 2002 were the most similar and more extreme in terms of the large-scale fields of basic meteorological quantities. The similar features of these episodes are specifically an intensive influx of moisture into Central Europe and intensive upward motions in the precipitation area. The extremeness of upper- and low-level potential vorticity fields was evaluated to diagnose the behavior of the cyclone and frontal precipitation bands accompanying it. The suitable spatial configuration of positive upper- and low-level potential vorticity anomalies induced an additional amplification of upward motions in the precipitation area that apparently contributed to triggering the heavy precipitation over Central Europe. On the whole, quantities reached more extreme values during the second episode in 2002. 相似文献
92.
Groundwater ‐ the disregarded component in lake water and nutrient budgets. Part 1: effects of groundwater on hydrology 下载免费PDF全文
Lake eutrophication is a large and growing problem in many parts of the world, commonly due to anthropogenic sources of nutrients. Improved quantification of nutrient inputs is required to address this problem, including better determination of exchanges between groundwater and lakes. This first of a two‐part review provides a brief history of the evolution of the study of groundwater exchange with lakes, followed by a listing of the most commonly used methods for quantifying this exchange. Rates of exchange between lakes and groundwater compiled from the literature are statistically summarized for both exfiltration (flow from groundwater to a lake) and infiltration (flow from a lake to groundwater), including per cent contribution of groundwater to lake‐water budgets. Reported rates of exchange between groundwater and lakes span more than five orders of magnitude. Median exfiltration is 0.74 cm/day, and median infiltration is 0.60 cm/day. Exfiltration ranges from near 0% to 94% of input terms in lake‐water budgets, and infiltration ranges from near 0% to 91% of loss terms. Median values for exfiltration and infiltration as percentages of input and loss terms of lake‐water budgets are 25% and 35%, respectively. Quantification of the groundwater term is somewhat method dependent, indicating that calculating the groundwater component with multiple methods can provide a better understanding of the accuracy of estimates. The importance of exfiltration to a lake budget ranges widely for lakes less than about 100 ha in area but generally decreases with increasing lake area, particularly for lakes that exceed 100 ha in area. No such relation is evident for lakes where infiltration occurs, perhaps because of the smaller sample size. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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94.
Karel Šilhán Rudolf Brázdil Tomáš Pánek Petr Dobrovolný Lucie Kašičková Radim Tolasz Ondřej Turský Marek Václavek 《地球表面变化过程与地形》2011,36(14):1898-1909
Rockfall is an important process in the final sculpturing of escarpments and scree slopes that originate in bedrock landslides in the Flysch Carpathians. The spatio‐temporal characteristics of rockfall activity were studied at four localities representative of old landslides in the highest part of the Czech Flysch Carpathians (Moravskoslezské Beskydy Mountains). Historical activity, chronology, and spatial context of rockfall activity were reconstructed using dendrogeomorphic techniques and rockfall rate index (RR). A total of 1132 increment cores from 283 trees growing in the rockfall transport and accumulation zones enabled the dating of 989 rockfall events. Reconstruction of a 78‐year‐long RR chronology suggests similar rockfall histories and trends at all study sites, indicating the existence of major common factors driving rockfall dynamics in the region. Temporal analysis and correlation of the RR series obtained with monthly mean temperatures, numbers of days with temperature transitions through 0 °C and monthly precipitation totals show that meteorological characteristics have evident but variable influence on rockfall activity. The most important factor is the effect of freeze–thaw cycles throughout the year, supplemented by low temperatures, especially during autumn. The influence of precipitation totals is of lesser importance. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
95.
David L. McCollum Volker Krey Keywan Riahi Peter Kolp Arnulf Grubler Marek Makowski Nebojsa Nakicenovic 《Climatic change》2013,119(2):479-494
This paper assesses three key energy sustainability objectives: energy security improvement, climate change mitigation, and the reduction of air pollution and its human health impacts. We explain how the common practice of narrowly focusing on singular issues ignores potentially enormous synergies, highlighting the need for a paradigm shift toward more holistic policy approaches. Our analysis of a large ensemble of alternate energy-climate futures, developed using MESSAGE, an integrated assessment model, shows that stringent climate change policy offers a strategic entry point along the path to energy sustainability in several dimensions. Concerted decarbonization efforts can lead to improved air quality, thereby reducing energy-related health impacts worldwide: upwards of 2–32 million fewer disability-adjusted life years in 2030, depending on the aggressiveness of the air pollution policies foreseen in the baseline. At the same time, low-carbon technologies and energy-efficiency improvements can help to further the energy security goals of individual countries and regions by promoting a more dependable, resilient, and diversified energy portfolio. The cost savings of these climate policy synergies are potentially enormous: $100–600 billion annually by 2030 in reduced pollution control and energy security expenditures (0.1–0.7 % of GDP). Novel aspects of this paper include an explicit quantification of the health-related co-benefits of present and future air pollution control policies; an analysis of how future constraints on regional trade could influence energy security; a detailed assessment of energy expenditures showing where financing needs to flow in order to achieve the multiple energy sustainability objectives; and a quantification of the relationships between different fulfillment levels for energy security and air pollution goals and the probability of reaching the 2 °C climate target. 相似文献
96.
97.
Nonstandard theories of fundamental interactions typically predict the existence of new kinds of weakly interacting particles.
These can escape freely from stellar interiors and act as additional source of cooling. Considerable agreement of a variety
of astrophysical observations with standard physics can serve as a source of constraints on non-standard ideas. In this paper
we consider G117-B15A pulsating white dwarf for which the secular rate, at which the period of its fundamental mode increases,
has been accurately measured. This star has been claimed the most stable oscillator ever recorded in the optical band. Because
an additional channel of energy loss would speedup the cooling rate, one is able to use this stability to derive a bound on
axion mass and on theories with large extra dimensions. We also point to the possibility of using similar arguments to constrain
supersymmetric paticles.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
98.
Pavel Mayer Marek Wolf P. G. Niarchos K. D. Gazeas V. N. Manimanis Drahomír Chochol 《Astrophysics and Space Science》2006,304(1-4):39-41
New precise times of minimum light for several early-type eclipsing binaries were obtained at three observatories. The changes of period of the following measured binaries are discussed: V1182 Aql, LY Aur, SZ Cam, FZ CMa, QZ Car, LZ Cen, V606 Cen, AH Cep and TU~Mus. 相似文献
99.
100.