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971.
972.
973.
胡连英 《地球科学与环境学报》1988,(3)
本文论述了中国强震迁移与现代地壳波浪运动间的关系,指出了中国强震时空分布上的波浪性、方向性及丛集性特征,并将中国强震运动划分为天平式运动、单波系波浪运动、双波系波浪运动、多波系波浪运动等类型,进而对强震机制进行了探讨,指出强震波带和强震丛集区仍是今后强震活动的主要场所。 相似文献
974.
Summary The geology and structure of the Mexico Basin are discussed and hypotheses developed to explain the magnification of wave amplitudes during the 1985 earthquake. 相似文献
975.
976.
在远场正演计算的基础上,运用30°~90°的四个不同深源远震记录波形,通过试错法选取台站下方的结构,借助波场反向重建算法,反演确定宜昌台站下方的速度结构。这一算法的实现有助于提高用试错法所得结果的可靠性和精确度,对于利用天然地震资料研究地球深部构造有一定的实用价值。 相似文献
977.
N. Kontopoulos 《Mathematical Geology》1984,16(2):207-211
Grain-size spectra maps of sands from beaches of the western Peloponnese are related to statistical parameters and can be used to infer characteristics of the sedimentation process involved which were unresolved by previous statistical analysis. On the basis of similarities in spectral patterns, the studied beaches fall into four groups: A, B, C, and D. The periodicity observed on the sinuous pattern of the spectra map of groups A and B is interpreted as indicating edge-wave activity. Regarding group D, the gradual W—E increase of particle size along the coast suggests a W—E increase of wave energy, which is also reflected by the inclined trend of the spectra map. Lack of periodicity on the contour pattern of group C probably reflects intensive sample-to-sample sorting variation. 相似文献
978.
G. D. Hess 《Boundary-Layer Meteorology》2004,110(3):319-355
The presence of a low-level, capping inversion layer will affect the height and structure of the planetary boundary layer (PBL). Results from models of varying levels of sophistication, including analytical, turbulent kinetic energy (TKE), second-order closure (SOC), large-eddy simulation (LES) and direct numerical simulation (DNS) models, are used to investigate this influence for the neutral, barotropic PBL. Predicted and observed profiles of stress and geostrophic departure components, and integral measures, such as the parameters of Rossby-number similarity theory, are compared for the KONTUR, Marine Stratocumulus, JASIN, Leipzig, Pre-Wangara and Upavon field experiments.Analytical models of the equilibrium value of inversion height zi, which depend on the surface friction velocity u*, and both the Coriolis parameter f and the free-flow Brunt-Väisälä frequency N, are found to give reasonable estimates of the PBL height. They also indicate that only the KONTUR and Marine Stratocumulus experiments were strongly influenced by N. More quantitative comparisons would require larger, more comprehensive datasets. The effects of the presence of a capping inversion on the profile structure were found to be insignificant for h* = |f|zi/u* > 0.15.The simple analytical model performed quite well over all values of h*; it predicted the profiles of the longitudinal stress component (in the direction of the surface stress) better than the lateral component. The more advanced models performed well for small values of h* (for flow over the sea), but systematically underestimated the cross-isobaric angle for flow over land. These models predicted the profiles of the lateral stress component better than the longitudinal component. The profiles of the analytical model agreed with those of the advanced models when the constant eddy viscosity of the outer layer was increased.Agreement with DNS was achieved by increasing the eddyviscosity of the analytical model by a factor of 5.Zilitinkevich and Esau(2002, Boundary-Layer Meteorology, 104, 371–379)suggest that the neutral, barotropic values of A and B of Rossby-numbersimilarity theory are not universal constants, but depend on the ratio N/|f|. The dependence for A and B is calculated using the analytical model and TKE models. Over the sea (h* 0.1; N/|f| 100, where we have used the Zilitinkevich-Esau relation to convert between h* and N/|f|) there is agreement between the model predictions and observations; however over land where the equilibrium boundary-layer height is greater (h* 0.35; N/|f| 10) the inconsistency between the advanced model predictions (TKE, SOC, LES, and DNS) and observations, as noted previously by Hess and Garratt, still exists. We attribute this disagreement to violations of the strict assumptions of steady, horizontally homogeneous, neutral, barotropic conditions implicit in the observations. At small values of zi and a strongly stable background stratification (h* 0.04; N/|f| 1000) both the TKE and analytical models predict that A and B depend significantly on h*, however observations are unavailable to confirm these predictions. Zilitinkevich and Esau call this case the `long-lived near-neutral PBL', and state that it is found in cold weather at high latitudes. 相似文献
979.
信号的时频分布具有比时间尺度分布更高的描述和刻画非稳态地震波信号的能力,进一步提高信号的时频聚集性和尽可能减小交叉项干扰是时频分析发展的方向。基于高阶矩时频分布理论,本首次提出了将其应用于数字化地震波形资料分析和处理的技术途径和方法。通过对仿真信号的Choi-Willams各阶矩时频分布与Wigner各阶矩时频分布的对比和交叉项干扰的理论分析,认为Choi-willams高阶矩时频分布具有时频聚集性高和交叉干扰项小的特点,在提高处理数字化地震波特性参数精度和地震应急技术系统的智能化程度等方面具有潜在应用前景。 相似文献
980.
INFLUENCE OF THE SURFACE AIR TEMPERATURE OVER ASIAN-PACIFIC REGION ON THE SUMMERTIME NORTHEASTERN ASIAN BLOCKING HIGH* 下载免费PDF全文
Synthesis analysis and singular value decomposition (SVD) methods were used to study the impact of surface air temperature (SAT) over Asian-Pacific region on the summertime northeastern Asian blocking high (NABH) with NCEP/NCAR Reanalysis Data.The results showed that 500 hPa geopotential height and SAT fields over Asian-Pacific region shared the similar pattern of East Asian Pacific (EAP) wave train;there was steady remote response relationship between the EAP wave train in summer and the "+-+" pattern of tropical SAT in zonal direction from former winter to summer;there were two relative negative(positive) Walker circulations over the tropical Indian Ocean and Pacific when being more(less) summertime NABH. The influence of sea surface temperature anomaly (SSTA) on the summertime NABH was possibly as follows.The special distribution of SSTA in tropical zonal direction continuously forced the tropical convection and zonal circulation from former winter to summer,and led them to act anomaly.Finally the abnormal conditions were transported to middle-high latitudes through EAP wave train and yielded the advantageous or disadvantageous atmospheric circulation background for the summertime NABH. 相似文献