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Gualtiero Badin Jörn Behrens Christian Franzke Jens Rademacher 《地球物理与天体物理流体动力学》2019,113(5-6):425-427
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Organized spatial distribution of plants (plant zonation) in salt marshes has been linked to the soil aeration condition in the rhizosphere through simplistic tidal inundation parameters. Here, a soil saturation index (ratio of saturation period to tidal period at a soil depth) is introduced to describe the soil aeration condition. This new index captures the effects of not only the tidal inundation period and frequency but also the flow dynamics of groundwater in the marsh soil. One‐dimensional numerical models based on saturated flow with the Boussinesq approximations and a two‐dimensional variably saturated flow model were developed to explore the behaviour of this new soil aeration variable under the influence of spring‐neap tides. Simulations revealed two characteristic zones of soil aeration across the salt marsh: a relatively well aerated near‐creek zone and a poorly aerated interior zone. In the near‐creek zone, soils undergo periodic wetting and drying as the groundwater table fluctuates throughout the spring‐neap cycle. In the interior, the soil remains largely water saturated except for neap tide periods when limited drainage occurs. Although such a change of soil aeration condition has been observed in previous numerical simulations, the soil saturation index provides a clear delineation of the zones that are separated by an ‘inflexion point’ on the averaged index curve. The results show how the saturation index represents the effects of soil properties, tidal parameters and marsh platform elevation on marsh soil aeration. Simulations of these combined effects have not been possible with traditional tidal inundation parameters. The saturation index can be easily derived using relatively simple models based on five non‐dimensional variables. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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V. V. Alpatov V. I. Badin I. A. Grebnev M. G. Deminov D. S. Faermak 《Geomagnetism and Aeronomy》2012,52(6):793-796
The results of a theoretical analysis of the radial distribution of electron temperature T e in the area of heating of the lower ionosphere by intense shortwave radiation are presented. It was established that effective radius r eff of heating at a certain height may differ significantly from the characteristic radius of illumination of the ionosphere (a) by radiation at this height. At the boundary of the heating area (r = r eff ), the characteristic radial scale of T e changes is less than the corresponding scale of changes in the squared amplitude of the radiation electric field, and it is almost independent of the amplitude value; i.e., the formation of a relatively strong T e gradient at such a boundary is a common feature of heating of the lower ionosphere by intense shortwave radiation. 相似文献
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V. I. Badin 《Geomagnetism and Aeronomy》2011,51(2):178-186
A method for detecting discrete equidistant spectra in high-latitude magnetic observations is proposed. The method finds approximate
solutions of the classical Schuster problem, which finds a hidden periodicity in observations with considerable noise. The
usage of difference signals makes it possible to increase the latitudinal resolution of the magnetometric diagnostics. The
equidistant spectra of two different types have been detected based on the proposed method. The spectra of the first type
are interpreted as frequencies of coupled compressional-transverse magnetohydrodyncompressionalamic oscillations in the magnetospheric
cavity. The origin of the second type of spectra can be related to a rotating source, i.e., a small-scale vortex of magnetospheric
convection. Such an interpretation takes into consideration the Doppler frequency shift caused by entrainment of the ionospheric
neutral gas by magnetospheric convection. The results confirm the conclusion that discrete auroral frequencies are stable
under disturbed conditions. 相似文献
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Influence of leaf and canopy characteristics on rainfall interception and urban hydrology 总被引：2，自引：1，他引：1
Considering the rapid expansion of urban populations and the corresponding urbanization of landscapes, a dearth of knowledge exists regarding the role of urban vegetation in modulating urban ecosystem functioning. In response to the need for the development of new approaches to quantify ecohydrological processes along urban-to-rural gradients at alternate scales, this study explores the relationship between individual plant selection choices in landscaping and changes in urban hydrological functioning. This research examines differences in the variation of rainfall interception, leaf hydrophobicity, canopy structure, and water storage, between 13 species in an urban, semi-arid location. The species studied were selected based on resident preferences, and hence this research considers the role that urban residents play, through individual choices, in modifying the ecohydrology of an urban watershed. Rainfall interception, canopy surface storage, leaf hydrophobicity, and water droplet retention were significantly different between species. Results indicate that individual choice in plant selection for landscaping may influence urban hydrology. 相似文献
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G. Badin 《地球物理与天体物理流体动力学》2013,107(5):526-540
The surface quasi-geostrophic approximation is re-written in an oceanic context using the two-dimensional semi-geostrophic approximation. The new formulation allows to take into account the presence of out-of-balance flow features at scales comparable to or smaller than the Rossby radius of deformation and for small bulk Richardson numbers. Analytical solutions show that, while the surface quasi-geostrophic approximation tends to underestimate the buoyancy anomaly, the inclusion of finite Rossby number allows for larger values of the buoyancy anomaly at depth. The projection of the surface semi-geostrophic solution on the first baroclinic modes is calculated. The result of the projection is a functional form that decreases with the values of the Rossby number and toward smaller scales. Solutions for constant and exponential profile for the background potential vorticity are compared. Results of the comparison show that, in agreement with the results found for balanced flows, even for large Rossby number the exponential profile for the background potential vorticity retains smaller values for the buoyancy anomaly at depth than the solution found using a constant potential vorticity profile. 相似文献
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Geomagnetism and Aeronomy - A new foE model for the auroral region is constructed; the model is based on an analysis of the models of auroral electron precipitations, the boundaries of the discrete... 相似文献
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V. I. Badin 《Geomagnetism and Aeronomy》2016,56(1):87-94
Maps for standard deviations of the drift velocity of E layer ionosphere electrons in the radar field of vision were constructed with the aid of narrowband and low-pass filtering based on STARE Doppler data. In these maps, narrowband filtering reveals the geometric configurations of the excitation of particular ultralow-frequency (ULF) oscillations. Such a configuration indicates nonresonant origins of these oscillations. Low-pass filtering of the Doppler data revealed specific absorption of background ULF signals; this absorption is attributed to the resonance of magnetic field lines. Quantitative estimates for minimum frequencies of the resonant ULF absorption occurring in the eigenfrequency continuum of magnetic field lines were found. 相似文献