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81.
提出内蕴大地边值问题,使得有可能利用重力场边界观测研究地球重力场的内蕴结构。文中构造了椭球问题的迭代逼近求解程式,并给出了具体解式。 相似文献
82.
The gradient of CO_2 concentration, photosynthetically active radiation (PAR). net radiation.soil heat flux, profiles of wind speed, and air temperature and humidity were measured above awheat field during May and June 1985 at Beijing Agro-Ecosystems Experimental Station. Beijing,China. Fluxes of carbon dioxide, sensible heat, latent heat and momentum were calculated byusing the aerodynamic method. The observation site. equipment, calibration techniques, theerrors associated with the measurement, and the computational procedures are described. Theresults show that the diurnal variations of amplitude of CO_2 concentrations were 103.8 to 27. 0. 86.3 to 22.8 and 69.8 to 11.6 ppm: the average CO_2 concentrations were 331.5. 339.9 and 364.6 ppmfor the photosynthesis type, and 369.6. 364.0 and 375.2 ppm for the respiration type at 1. 2 and10 m above surface, respectively, from May 14 to June 15. In the daytime, transfer direction ofthe CO_2 fluxes and gradients is from air to crop canopy, and at noon (1100 to 1300 BT (BeijingTime)) the transfer rate reaches negative maximum value. At night, transfer of CO_2 fluxes andgradients is in the reversed direction and reaches positive maximum in the early morning (0400 to0600 BT). There are strong negative correlations between CO_2 flux and the net radiation (Rn),available energy (H LE). photosynthetically active radiation (PAR) and momentum flux (τ). 相似文献
83.
Ramesh V. Godbole 《Pure and Applied Geophysics》1977,115(5-6):1373-1381
A diagnostie method of cumulus parameterization is suggested in which vertical transport of horizontal momentum by cumulus-scale is derived by making use of large-scale vorticity as well as divergence budget equations. Data for composite monsoon depression over India available from our earlier studies used to test the method. As a first approximation, the results are obtained using only the vorticity budget equation.The results show that in the southwest sector of the monsoon depression, which is characterized by maximum cloudiness and precipitation, there is an excess of cyclonic vorticity in the lower troposphere and anticyclonic vorticity in the upper troposphere associated with the large-scale motion. The distribution of eddy vertical transport of horizontal momentum is such that anticyclonic vorticity is generated in the lower troposphere and cyclonic vorticity aloft. Cumulus-scale eddies thus work against the large-scale system and tend to off-set the large-scale imbalance in vorticity. 相似文献
84.
The balance conditions of relative angular momentum and time-mean kinetic energy and their annual variations are studied for the Northern Hemisphere tropical belt. The belt is divided into two roughly equal size parts, the monsoon and the extramonsoon regions. The data used consist of all available daily rawinsonde reports from the world areological network for the two 5-year periods 1958–63 and 1968–73.In winter, the trade winds in the monsoon and extramonsoon regions are both sources of westerly relative angular momentum for the middle latitude circulation. However, it is found that the angular momentum gained in the extramonsoon region of the Tropics is mostly destroyed by a net southward flow of mass in that region, and becomes regenerated in the monsoon region by a net northward flow of mass there. This excess of angular momentum together with the angular momentum picked up locally in the monsoon region is almost all exported across its northern boundary. It is further found that in winter the Tropics are also an important source of mean kinetic energy for middle latitudes. Again almost all export of kinetic energy was found to take place across the northern boundary of the monsoon sector. Most of this energy must be generated through the pressure gradient term inside the monsoon region itself, the transformation from transient eddy kinetic energy being very small. The proper evaluation of the pressure gradient appears to be the main stumbling block in the present study, preventing us from estimating the generation and thereby, as a residual, the frictional dissipation in the two regions.In summer, the extramonsoon region remains a source of angular momentum, but the monsoon region with its surface westerlies acts as a sink, leading to a sharp reduction (and even a midsummer reversal) of the export into middle latitudes. Also the export of mean kinetic energy almost vanishes in summer, except for a small southward transfer across the equator. The calculations for two 5-year periods give very similar estimates and thereby show the reliability of the results.Parts of this paper were presented at the International Symposium on Monsoons, March 7–12, 1977 in New Delhi, India. 相似文献
85.
86.
87.
The reflection and transmission phenomena of elastic waves incident at a corrugated interface between two dissimilar fibre‐reinforced elastic half‐spaces have been analysed. Using Rayleigh method of approximation, the expressions of the reflection and transmission coefficients are obtained in closed form for the plane interface as well as for the first order approximation of the periodic interface ζ = d cos px. All these reflection and transmission coefficients of regular and irregular waves are found to be the functions of angle of incidence and elastic parameters of the media. Moreover, the coefficients of irregularly reflected and transmitted waves are found to be proportional to the amplitude of the corrugated interface and are functions of the frequency of the incident wave. Numerical computations have been performed for a specific model to compute these coefficients and results obtained are shown graphically. The results of Singh and Singh (Sadhana 2004; 29 :249–257) and Ben‐Menahem and Singh (Seismic Waves and Sources. Springer: New York) have been derived from our analysis as particular cases. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
88.
J. Bhattacharjee 《Ocean Engineering》2009,36(11):831-841
In the present study, the effect of shear current on the propagation of flexural gravity waves is analyzed under the assumptions of linearized shallow-water theory. Explicit expressions for the reflection and transmission coefficients associated with flexural gravity wave scattering by a step discontinuity in both water depth and current speed are derived. Further, trapping and scattering of flexural gravity waves by a jet-like shear current with a top-hat profile are examined and certain limiting conditions for the waves to exist are derived. The effects of change in water depth, current speed, incident wavelength and the angle of incidence on the group and phase velocities as well as on the reflection and transmission characteristics are analyzed through different numerical results. 相似文献
89.
90.
In this paper, we delve into the dynamics of a barothropic relaxing medium under pressure perturbations originating from blast wave explosions in the milieu. Analyzing the problem within the viewpoint of the Lyakhov formalism of geodynamic systems, we derive a complex-valued nonlinear evolution equation which models the wave propagation of the pressure perturbations within the barothropic medium. As a result, we find that the previous system can be circularly polarized and hence support traveling rotating pressure excitations which profiles strongly depend upon their angular momenta. In the wake of these results, we address some physical implications of the findings alongside their potential applications. 相似文献