排序方式： 共有34条查询结果，搜索用时 68 毫秒
11.
M. B. Danard M. C. Rasmussen T. S. Murty R. F. Henry Z. Kowalik S. Venkatesh 《Natural Hazards》1989,2(2):153-171
Storm surges in the Beaufort Sea present a severe problem for navigation as well as for offshore oil drilling activities. Influence of ice cover on storm surges in the Beaufort Sea is examined making use of a numerical model as well as a set of observations. The automated shallow-water model of Henry has been modified to incorporate ice cover and is adapted to the Beaufort Sea. The leading edge of the permanent ice is calculated from the loci of identifiable points. Generalized similarity theory is employed to compute wind stresses. Simulations are made using model-predicted ice concentrations and observed ice concentrations. Ice motion is relatively small in units of model grid distance (approximately 18 km) during surges. Spherical effects are important and should be included in future adaptations of the model. Comparison of the computed surges with observed surges for eight different events showed reasonable agreement. 相似文献
12.
13.
Zygmunt Meyer 《Acta Geophysica》2011,59(2):317-333
The wind set-up of water level in a river is of great importance in many practical cases, notably in the river mouth section
where the slope of the free water table is very small (sometimes 10−5) and the wind shear stress acting at the water surface generates significant changes in the vertical velocity profile. If
the wind is blowing opposite to the main flow, an increase of water depth is observed. In the outlet area, the increase of
water depth can reach up to 0.5 m (Lower Odra River). The paper presents an analysis of wind set-up of water level based on
hydrodynamic principles. 相似文献
14.
Organochlorine pesticides in fish from the southern Baltic Sea: levels, bioaccumulation features and temporal trends during the 1995-2006 period 总被引：1，自引：0，他引：1
The levels of HCH isomers, HCB and summation DDTs were determined in five species of Baltic fish collected during 1995-2006. Some downward time trends of HCH isomer, pp'-DDE and pp'-DDD concentrations in Baltic fish were observed; in contrast, HCB and DDT concentrations did not exhibit any obvious trend. Concentrations of summation HCHs expressed on a lipid weight basis were very similar in all species studied. In contrast, concentrations of summation DDTs varied in tested species. The most abundant HCH isomer was beta-HCH and among DDT-related compounds, pp'-DDE prevailed. In our investigations the sampling sites were not a crucial factor for organochlorine pesticide concentrations and patterns observed in fish, but the occurrence of several inter-species differences in the bioaccumulation features of OC pesticides were observed. For cod there was a positive correlation between fish size (length) and summation DDT concentration. In herring, sprat and salmon samples, summation DDT concentrations were negatively correlated with fat content. 相似文献
15.
16.
17.
First, we investigated some aspects of tsunami–tide interactions based on idealized numerical experiments. Theoretically, by changing total ocean depth, tidal elevations influence the speed and magnitude of tsunami waves in shallow regions with dominating tidal signals. We tested this assumption by employing a simple 1-D model that describes propagation of tidal waves in a channel with gradually increasing depth and the interaction of the tidal waves with tsunamis generated at the channel's open boundary. Important conclusions from these studies are that computed elevations by simulating the tsunami and the tide together differ significantly from linear superposing of the sea surface heights obtained when simulating the tide and the tsunami separately, and that maximum tsunami–tide interaction depends on tidal amplitude and phase. The major cause of this tsunami–tide interaction is tidally induced ocean depth that changes the conditions of tsunami propagation, amplification, and dissipation. Interactions occur by means of momentum advection, bottom friction, and variable water flux due to changing total depth and velocity. We found the major cause of tsunami–tide interactions to be changing depth. Secondly, we investigate tsunami–tide interactions in Cook Inlet, Alaska, employing a high-resolution 2-D numerical model. Cook Inlet has high tides and a history of strong tsunamis and is a potential candidate for tsunami impacts in the future. In agreement with previous findings, we find that the impacts of tsunamis depend on basin bathymetries and coastline configurations, and they can, in particular, depend on tsunami–tide interactions. In regions with strong tides and tsunamis, these interactions can result in either intensification or damping of cumulative tsunami and tide impacts, depending on mean basin depth, which is regulated by tides. Thus, it is not possible to predict the effect of tsunami–tide interaction in regions with strong tides without making preliminary investigations of the area. One approach to reduce uncertainties in tsunami impact in regions with high tides is to simulate tsunamis together with tidal forcing. 相似文献
18.
19.
20.
The influence of industrial immissions on the magnetic susceptibility of soils in upper Silesia 总被引：4，自引：0，他引：4
Zygmunt Strzyszcz Tadeusz Magiera Friedrich Heller 《Studia Geophysica et Geodaetica》1996,40(3):276-286
Summary Samples of metallurgical dusts and fly ashes from coal power plants and iron works in Upper Silesia as well as soil profiles
in the close vicinity of these plants and in Ojcow National Park (ca. 25 km east of the industrial area) have been studied
magnetically and mineralogically. The metallurgical dusts and fly ashes are highly enriched in ferromagnetic minerals. The
topsoils from profiles collected near the plants have very high values of magnetic susceptibility while susceptibility in
the fermentation and humic subhorizons in soil profiles from Ojcow National Park is considerably increased. The magnetic properties
of the metallurgical dusts and fly ashes such as frequency dependence of susceptibility, saturation remanence or coercivity
are similar to those observed in the top horizons of the soils. They are mostly related to the occurrence of large (multidomain)
grains of non-stoichiometric magnetite ranging from 1 to 20 μm. The similarity of the magnetic particles in the soils is taken
as evidence of an anthropogenic origin. They are responsible for the high soil susceptibilities in Upper Silesia and in adjacent
areas. Some of the magnetic particles carry substantial quantitities of trace elements such as Pb, Ni, Zn and Cu. Field and
laboratory susceptibility measurements can therefore be used as a simple and costeffective method of detecting the presence
of heavy metals in the soils of this area. 相似文献