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1.
A. Hruška 《Astrophysics and Space Science》1977,50(1):153-161
One component of a three-fluid adiabatic plasma is under certain conditions contained in a restricted region of space by a large-scale electrostatic field generated within the plasma. The containment is discussed here for plasma consisting of ions and two populations of electrons characterized by different pitch angle distribution functions.The bouncing motion of electrons along open fieldlines between a magnetic mirror and an electrostatic mirror produces a velocity distribution function similar to that generated by bouncing particles on closed fieldlines. 相似文献
2.
3.
Jakub T. Szmigielski S. Lee Barbour Sean K. Carey John Kurylo A. F. McClymont M. Jim Hendry 《Hydrogeology Journal》2018,26(7):2341-2356
Steelmaking-coal waste rock placed in mountain catchments in the Elk Valley, British Columbia, Canada, drain constituents of interest (CIs) to surface water downgradient of the waste rock dumps. The role of groundwater in transporting CIs in the headwaters of mountain catchments is not well understood. This study characterizes the physical hydrogeology of a portion of a 10-km2 headwater catchment (West Line Creek) downgradient of a 2.7-km2 waste rock dump placed over a natural headwater valley-bottom groundwater system. The study site was instrumented with 13 monitoring wells. Drill core samples were collected to determine subsurface lithology and geotechnical properties. The groundwater system was characterized using field testing and water-level monitoring. The valley-bottom sediments were composed of unconsolidated glacial and meltwater successions (<64 m thick) deposited as a series of cut and fill structures overlying shale bedrock. An unconfined basal alluvial aquifer located above fractured bedrock was identified as the primary conduit for groundwater flow toward Line Creek (650 m from the toe of the dump). Discharge through the basal alluvial aquifer was estimated using the geometric mean hydraulic conductivity (±1 standard deviation). These calculations suggest groundwater discharge could account for approximately 15% (ranging from 2 to 60%) of the total water discharged from the watershed. The residence time from the base of the waste rock dump to Line Creek was estimated at <3 years. The groundwater system was defined as a snowmelt (i.e., nival) regime dominated by direct recharge (percolation of precipitation) across the catchment. 相似文献
4.
5.
A. Hruška 《Astrophysics and Space Science》1980,71(2):459-474
Stationary convection of an isotropic, infinitely conducting plasma in a magnetic field with non-trivial geometry is discussed under the assumption that the inertial term in the equation of motion may be ignored. The energy gained or lost by a volume element of plasma per unit time does not vary along the field-lines. Simple relations between the components of the current density, depending on the field-line geometry, exist. Similar relations hold for the components of the plasma velocity.The theoretical analysis is applied to the geomagnetically-quiet plasma sheet and a qualitative physical picture of the sheet is suggested. The observed structure of the sheet is compatible with Axford-Hines type of convection perhaps combined with a low-speed flow from a distant neutral point. The magnetic-field-aligned currents are driven by the deformations of the closed field-lines which are enforced by the solar wind. 相似文献
6.
Wenjuan Zheng Anna Lamačová Xuan Yu Pavel Krám Jakub Hruška Pavel Zahradníček Petr Štěpánek Aleš Farda 《水文研究》2021,35(9):e14281
Climate warming is having profound effects on the hydrological cycle by increasing atmospheric demand, changing water availability, and snow seasonality. Europe suffered three distinct heat waves in 2019, and 11 of the 12 hottest years ever recorded took place in the past two decades, which will potentially change seasonal streamflow patterns and long-term trends. Central Europe exhibited six dry years in a row since 2014. This study uses data from a well-documented headwater catchment in Central Europe (Lysina) to explore hydrological responses to a warming climate. We applied a lumped parameter hydrologic model Brook90 and a distributed model Penn State Integrated Hydrologic Model (PIHM) to simulate long-term hydrological change under future climate scenarios. Both models performed well on historic streamflow and in agreement with each other according to the catchment water budget. In addition, PIHM was able to simulate lateral groundwater redistribution within the catchment validated by the groundwater table dynamics. The long-term trends in runoff and low flow were captured by PIHM only. We applied different EURO-CORDEX models with two emission scenarios (Representative Concentration Pathways RCP 4.5, 8.5) and found significant impacts on runoff and evapotranspiration (ET) for the period of 2071–2100. Results from both models suggested reduced runoff and increased ET, while the monthly distribution of runoff was different. We used this catchment study to understand the importance of subsurface processes in projection of hydrologic response to a warming climate. 相似文献
7.
Réka?LukácsEmail author Szabolcs?Harangi Olivier?Bachmann Marcel?Guillong Martin?Dani?ík Yannick?Buret Albrecht?von?Quadt István?Dunkl László?Fodor Jakub?Sliwinski Ildikó?Soós János?Szepesi 《Contributions to Mineralogy and Petrology》2015,170(5-6):52
A silicic ignimbrite flare-up episode occurred in the Pannonian Basin during the Miocene, coeval with the syn-extensional period in the region. It produced important correlation horizons in the regional stratigraphy; however, they lacked precise and accurate geochronology. Here, we used U–Pb (LA-ICP-MS and ID-TIMS) and (U–Th)/He dating of zircons to determine the eruption ages of the youngest stage of this volcanic activity and constrain the longevity of the magma storage in crustal reservoirs. Reliability of the U–Pb data is supported by (U–Th)/He zircon dating and magnetostratigraphic constraints. We distinguish four eruptive phases from 15.9 ± 0.3 to 14.1 ± 0.3 Ma, each of which possibly includes multiple eruptive events. Among these, at least two large volume eruptions (>10 km3) occurred at 14.8 ± 0.3 Ma (Demjén ignimbrite) and 14.1 ± 0.3 Ma (Harsány ignimbrite). The in situ U–Pb zircon dating shows wide age ranges (up to 700 kyr) in most of the crystal-poor pyroclastic units, containing few to no xenocrysts, which implies efficient recycling of antecrysts. We propose that long-lived silicic magma reservoirs, mostly kept as high-crystallinity mushes, have existed in the Pannonian Basin during the 16–14 Ma period. Small but significant differences in zircon, bulk rock and glass shard composition among units suggest the presence of spatially separated reservoirs, sometimes existing contemporaneously. Our results also better constrain the time frame of the main tectonic events that occurred in the Northern Pannonian Basin: We refined the upper temporal boundary (15 Ma) of the youngest counterclockwise block rotation and the beginning of a new deformation phase, which structurally characterized the onset of the youngest volcanic and sedimentary phase. 相似文献
8.
Kryštof Verner Jiří Žák Jaroslava Pertoldová Josef Šrámek Jiří Sedlák Jakub Trubač Patricie Týcová 《International Journal of Earth Sciences》2009,98(3):517-532
The Plechy pluton, southwestern Bohemian Massif, represents a late-Variscan, complexly zoned intrusive center emplaced near
the crustal-scale Pfahl shear zone; the pluton thus provides an opportunity to examine the interplay among successive emplacement
of large magma batches, magmatic fabric acquisition, and the late-Variscan stress field associated with strike-slip shearing.
The magmatic history of the pluton started with the emplacement of the porphyritic Plechy and Haidmühler granites. Based on
gravity and structural data, we interpret that the Plechy and Haidmühler granites were emplaced as a deeply rooted, ∼NE–SW
elongated body; its gross shape and internal fabric (steep ∼NE–SW magmatic foliation) may have been controlled by the late-Variscan
stress field. The steep magmatic foliation changes into flat-lying foliation (particularly recorded by AMS) presumably as
a result of divergent flow. Magnetic lineations correspond to a sub-horizontal ∼NE–SW finite stretch associated with the divergent
flow. Subsequently, the Třístoličník granite, characterized by steep margin-parallel magmatic foliation, was emplaced as a
crescent-shaped body in the central part of the pluton. The otherwise inward-younging intrusive sequence was completed by
the emplacement of the outermost and the most evolved garnet-bearing granite (the Marginal granite) along the southeastern
margin of the pluton.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
9.
A. Hruška 《Planetary and Space Science》1982,30(7):701-709
A mathematical formalism describing the relation between the structure of a one-fluid, collisionless plasma and the topological features of the vector lines of the magnetic, velocity and electric fields is suggested and a rigorous approach to the problem of determining the local features of the plasma from the properties of the velocity field v, observed at a chosen point of space, is developed. The limits to drawing conclusions from the observational data (such as encountered in magnetospheric physics) are outlined in Section 2.Energization of a plasma during a stationary convection is an example of a process characterized by the properties of the tensor . In particular, if the plasma density and the velocity and pressure components in a volume element of the plasma are known, then the time rates of change of the kinetic and internal energies are described by stretchings of the element and by its shearing in the surface defined by the vectors of magnetic field and perpendicular velocity. Criteria according to which plasma gains or loses kinetic and internal energies are derived. 相似文献
10.
Filip Oulehle Milan Fischer Jakub Hruška Tomáš Chuman Pavel Krám Tomáš Navrátil Miroslav Tesař Miroslav Trnka 《水文研究》2021,35(5):e14204
In 1994, a network of small catchments (GEOMON) was established in the Czech Republic to determine input–output element fluxes in semi-natural forest ecosystems recovering from anthropogenic acidification. The network consists from 16 catchments and the primary observations of elements fluxes were complemented by monitoring of biomass stock, element pools in soil and vegetation, and the main water balance components. Over last three decades, reductions of SO2, NOx and NH3 emissions were followed by sulphur (S) and nitrogen (N) deposition reductions of 75% and 30%, respectively. Steeper declines of strong acid anion concentrations compared to cations (Ca, Mg, Na, K, NH4) in precipitation resulted in precipitation pH increase from 4.5 to 5.2 in bulk precipitation and from 4.0 to 5.1 in spruce throughfall. Stream chemistry responded to changes in deposition: S leaching declined. However at majority of catchments soils acted as a net source of S to runoff, delaying recovery. Stream pH increased at acidic streams (pH < 6) and aluminium concentration decreased. Stream nitrate (NO3) concentration declined by 60%, considerably more than N deposition. Stream NO3 concentration was tightly positively related to stream total dissolved nitrogen to total phosphorus (P) ratio, suggesting the role of P availability on N retention. Trends in dissolved organic carbon fluxes responded to both acidification recovery and to runoff temporal variation. An exceptional drought occurred between 2014 and 2019. Over this recent period, streamflow decreased by ≈ 40% on average compared to 1990s, due to the increases of soil evaporation and vegetation transpiration by ≈ 30% and declines in precipitation by ≈ 15% on average across the elevational gradient. Sharp decreases of stream runoff at catchments <650 m a.s.l. corresponded to areas of recent forest decline caused by bark beetle infestation on drought stressed spruce forests. Understanding of the interactions among legacies of acidification and eutrophication, drought effects on the water cycle and forest disturbance dynamics is requisite for effective management of forested ecosystems under anthropogenic influence. 相似文献