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1.
In this paper,a relatively systematic climatological research on the onset of the Asian tropical summer monsoon(ATSM)was carried out.Based on a unified index of the ATSM onset,the advance of the whole ATSM was newly made and then the view that the ATSM firstly breaks out over the tropical eastern Indian Ocean and the middle and southern Indo-China Peninsula was further documented,which was in the 26th pentad(about May 10),then over the South China Sea(SCS)in the 28th pentad.It seems that the ATSM onset over the two regions belongs to the different stages of the same monsoon system.Then,the onset mechanism of ATSM was further investigated by the comprehensive analysis on the land-sea thermodynamic contrast,intraseasonal oscillation,and so on,and the several key factors which influence the ATSM onset were put forward.Based on these results,a possible climatological schematic map that the ATSM firstly breaks out over the tropical eastern Indian Ocean,the Indo-China Peninsula,and the SCS was also presented, namely seasonal evolution of the atmospheric circulation was the background of the monsoon onset;the enhancement and northward advance of the convections,the sensible heating and latent heating over the Indo-China Peninsula and its neighboring areas,the dramatic deepening of the India-Burma trough,and the westerly warm advection over the eastern Tibetan Plateau were the major driving forces of the summer monsoon onset,which made the meridional gradient of the temperature firstly reverse over this region and ascending motion develop.Then the tropical monsoon and precipitation rapidly developed and enhanced. The phase-lock of the 30-60-day and 10-20-day low frequency oscillations originated from different sources was another triggering factor for the summer monsoon onset.It was just the common effect of these factors that induced the ATSM earliest onset over this region. 相似文献
2.
New Reynolds' mean momentum equations including both turbulent viscosity and dispersion are used to analyze atmospheric balance motions of the planetary boundary layer. It is pointed out that turbulent dispersion with r 0 will increase depth of Ekman layer, reduce wind velocity in Ekman layer and produce a more satisfactory Ekman spiral lines fit the observed wind hodograph. The wind profile in the surface layer including tur-bulent dispersion is still logarithmic but the von Karman constant k is replaced by k1 = 1 -2/k, the wind increasesa little more rapidly with height. 相似文献
3.
Variational Principle of Instability of Atmospheric Motions 总被引：6，自引：4，他引：2
Problems of instability of rotating atmospheric motions are investigated by using nonlinear governing equations and the variational principle. The method suggested in this paper is universal for obtaining criteria of instability in all models with all possible basic flows. For example, the model can be barotropic or baroclinic, layer or continuous, quasi-geostrophic or primitive equations; the basic flow can be zonal or nonzonal, steady or unsteady.Although the basic flows possess a great deal of variety, they all are the stationary points in the functional space determined by an appropriate invariant functional. The basic flow is an unsteady one if the conservation of angular momentum is included in the associated functional.The second variation, linear or nonlinear, gives the criteria of instability. Especially, the general criteria of instability for unsteady basic flow, orographically disturbed flow as well as nongeostrophic flow are first obtained by the method described in this paper.It is also sh 相似文献
4.
Numerical models of trajectories of small aerosol spheres relative to oblate spheroids were used to determine ice crystal scavenging efficiencies. The models included the effects of aerodynamic flow about the ice particle, gravity, aerosol particle inertia and drag and electrostatic effects. Two electric configurations of the ice particle were investigated in detail. The first applied a net charge to the ice particle, of magnitude equal to the mean thunderstorm charge distribution, while the second applied a charge distribution, with no net charge, to the ice particle to model the electric multipole charge distribution. The results show that growing ice crystals with electric multipoles are better scavengers than single ice crystals with net thunderstorm charges, especially in the Greenfield gap (0.1 to 1.0 um), and that larger single crystals are better scavengers than smaller single crystals. The results also show that the low density ice crystals are more effective scavengers with net charges than th 相似文献
5.
Sun et al., (1983) have given some favourable environmental conditions and have shown that there are four common features in convective rainstorms. In this paper, an important process of evolution of cloud systems was revealed when heavy rainfall occurred based on the diagnostic analysis of heavy rainfall cases. When the different cloud systems merge into a large one, the mesoscale heavy rainfall occurs and enhances. In other words, the process of evolution of cloud systems emphasized in this paper is the process of interaction between two cloud systems when the heavy rainfall occurs. The favourable environmental condition is also investigated. 相似文献
6.
Approximations of the Scattering Phase Functions of Particles 总被引：1，自引：0，他引：1
Based on anomalous diffraction theory and the modified Rayleigh-Debye approximation, a physically realistic model in bridging form is described to approximate the scattering phase function of particles. When compared with the exact method, the bridging technique reported here provides a reasonable approximation to the Mie results over a broader range of angles and size parameters, and it demonstrates the advantage of being computationally economic. In addition, the new phase function model can be essentially extended to other shapes and conveniently used in more complicated scattering and emission problems related to the solutions of the radiative transfer equations. 相似文献
7.
A.Bandyopadhyay 《大气科学进展》1992,(1)
The split-explicit version of a limited area primitive equation barotropic model is formulated and tested for the prediction of movement of monsoon depressions. The model is integrated upto 48 hours with split-explicit time integration scheme (Gadd, 1978a) using input of four synoptic cases. The model is also integrated explicitly. The forecast results obtained from both the versions are compared and discussed. The computational time in former version is less than half of the computational time needed in explicit version. 相似文献
8.
Effect of the Interaction of Different Scale Vortices on the Structure and Motion of Typhoons 总被引：13，自引：1，他引：13
ＥｆｆｅｃｔｏｆｔｈｅＩｎｔｅｒａｃｔｉｏｎｏｆＤｉｆｆｅｒｅｎｔＳｃａｌｅＶｏｒｔｉｃｅｓｏｎｔｈｅＳｔｒｕｃｔｕｒｅａｎｄＭｏｔｉｏｎｏｆＴｙｐｈｏｏｎｓＣｈｅｎＬｉａｎｓｈｏｕ（陈联寿）（ＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＭｅｔ６ｏｒｏｌｏｇｉｃ... 相似文献
9.
ＩｎｔｅｒｎａｌＤｙｎａｍｉｃｓｏｆｔｈｅＧｅｎｅｒａｔｉｏｎｏｆＡｔｍｏｓｐｈｅｒｉｃＴｅｌｅｃｏｎｎｅｃｔｉｏｎＰａｔｔｅｒｎｓＬｉＺｈｉｊｉｎ（李志锦）ａｎｄＪｉＬｉｒｅｎ（纪立人）（ＩｎｓｔｉｔｕｔｅｏｆＡｔｍｏｓｐｈｅｒｉｃＰｈｙｓｉｃｓ，... 相似文献
10.
Ice nuclei-supersaturation spectra in the form of a Power Law ( Ni=RSir; B and y are empirical constants) have been expressed since 1973 when the curve was first introduced independentally by Gagin and Huffman. Experiments performed with a thermal gradient diffusion chamber in order to investigate the validity of the power curve. The results show that a linear curve fit to the data is as good as the power curve. The linear curve has the coefficients of correlation between 0.75 and 0.93 whereas the power curve fit to the same data has the coefficients between 0.82 and 0.93. The data reported by other workers, Zamurs and Jiusto and Zamurs et al., exhibit the same trend. 相似文献
11.
12.
Progresses in the research on physical processes of lightning discharge and electric structure of thunderstorm in the last decade in China have been reviewed. By using the self-developed lightning detecting and locating techniques with high temporal and spatial resolution, the characteristics and parameters of lightning discharge in some representative areas in China have been obtained. Observations on lightning activity were conducted for the first time in the Qinghai-Tibetan Plateau in 2002-2005, and the special characteristics of the thunderstorm and lightning activity in the plateau were revealed. The lightning spectra in the band of visible light were recorded, and the spectral lines were identified in detail with introduction of modern theories of atomic structure. The techniques on artificially altitude triggered lightning and related measurements under a harsh electromagnetic environment have been well developed. Evidences of bi-directional leader propagation were observed by means of optics and VHF radiation during the triggered lightning discharges. Some lightning protection devices have been tested using the artificial lightning triggering techniques. In addition, the correlation between lightning activities and weather and climate was preliminarily studied. 相似文献
13.
Luo Zhexian 《大气科学进展》1994,11(4):391-398
The effects of the Beta term on the typhoon structure are examined within the linear framework in terms of an analytical method of 2-D Fourier representation and numerical experiments by a Beta-plane quasi-geostrophic barotropic model. Results show that the joint effects of the difference of Rossby phase velocities and the dispersion of typhoon energy keep the maximum wind velocity reasonably evolving rather than irrestrictively increasing. On the one hand, the nonlinear advection accelerates typhoon vortex damping, and on the other, the high pressure system formed downstream due to energy dispersion makes it easy to maintain. 相似文献
14.
The 1970-1985 day to day averaged pressure dataset of Shanghai and the extension method in phase space are used to calculate the correlation dimension D and the second-order Renyi entropy K2 of the approximation of Kolmogorov's entropy, the fractional dimension D = 7.7-7.9 and the positive value K2 - 0.1 are obtained. This shows that the attractor for the short-term weather evolution in the monsoon region of China exhibits a chaotic motion. The estimate of K2 yields a predictable time scale of about ten days. This result is in agreement with that obtained earlier by the dynamic-statistical approach.The effects of the lag time i on the estimate of D and K2 are investigated. The results show that D and K2 are convergent with respect to i. The day to day averaged pressure series used in this paper are treated for the extensive phase space with T = 5, the coordinate components are independent of each other; therefore, the dynamical character quantities of the system are stable and reliable. 相似文献
15.
A global forecast model is used to examine various sensitivities of numerical predictions of three extreme winter storms that occurred near the eastern continental margin of North America: the Ohio Valley blizzard of January 1978, the New England blizzard of February 1978, and the Mid-Atlantic cyclone of February 1979. While medium-resolution simulations capture much of the intensification, the forecasts of the precise timing and intensity levels suffer from various degrees of error. The coastal cyclones show a 5-10 hPa dependence on the western North Atlantic sea surface temperature, which is varied within a range (± 2.5℃) compatible with interannual fluctuations. The associated vertical velocities and precipitation rates show proportionately stronger dependences on the ocean temperature perturbations. The Ohio Valley blizzard, which intensified along a track 700-800 km from the coast, shows little sensitivity to ocean temperature. The effect of a shift of - 10?latitude in the position of the snow bo 相似文献
16.
A photochemical model of the atmosphere constitutes a non–linear, non–autonomous dynamical system, enforced by the Earth’s rotation. Some studies have shown that the region of the mesopause tends towards non–linear responses such as period-doubling cascades and chaos. In these studies, simple approximations for the diurnal variations of the photolysis rates are assumed. The goal of this article is to investigate what happens if the more realistic, calculated photolysis rates are introduced. It is found that, if the usual approximations—sinusoidal and step fiunctions—are assumed, the responses of the system are similar: it converges to a 2–day periodic solution. If the more realistic, calculated diurnal cycle is introduced, a new 4–day subharmonic appear. 相似文献
17.
In Search of Warmer Climates? The Impact of Climate Change on Flows of British Tourists 总被引：10，自引：1，他引：9
David Maddison 《Climatic change》2001,49(1-2):193-208
This paper investigates the impact of climate change on the chosendestinations of Britishtourists. Destinations are characterised in terms of attractors includingclimate variables, traveland accommodation costs. These variables are used to explain the currentobserved pattern ofoverseas travel in terms of a model based upon the idea of utilitymaximisation. The approachpermits the trade-offs between climate and holiday expenditure to be analysedand effectivelyidentifies the optimal climate for generating tourism. The findings are usedto predict the impactof various climate change scenarios on popular tourist destinations. 相似文献
18.
This paper studies correlations between the spatial structure character of thermal forcing and deformation and the amplitude of rays of meridional wave train. It is shown that if thermal forcing appears a meridional linear variation the rays of quasi-stationary planetary wave may propagate along oblique lines and if the meridional variability of heat source has second order term the rays show distinct deformation as a great circular route. Additionally, the inhomogeneous distribution may cause lower frequency oscillations in mid- and low-latitudes. The combination of zonal and meridional wave numbers and distributive character of heat source may form an inverse mechanism of variational trend of generized wave energy, reflecting in some degree the physical process of transition between meridional and zonal flow patterns. 相似文献
19.
An ICSED (Improved Cluster Shade Edge-Detection) algorithm and a series of post-processing technique are discussed for automatic delineation of mesoscale structure of the ocean on digital IR images. The popular derivative-based edge operators are shown to be too sensitive to edge fine-structure and to weak gradients. The new edge-detection algorithm is ICSED (Improved Cluster Shade Edge-detection) method and it is found to be an excel lent edge detector that exhibits the characteristic of fine-structure rejection while retaining edge sharpness. This char acteristic is highly desirable for analyzing oceanographic satellite images. A sorting technique for separating clouds or land well from ocean at both day and night is described in order to obtain high quality mesoscale features on the IR image This procedure is evaluated on an AVHRR (Advanced Very High Resolution Radiometer) image with Kuroshio. Results and analyses show that the mesoscale features can be well identified by using ICSED algorithm. 相似文献
20.
B. I. Gartsman L. I. Mezentseva T. S. Menovshchikova N. Yu. Popova O. V. Sokolov 《Russian Meteorology and Hydrology》2014,39(4):260-270
Analyzed are the synoptic and hydrological conditions of the generation of extremely high water content of Primorye rivers in the autumn of 2012. Revealed are the general features of atmospheric circulation, precipitation, water content, and hydrological regime of rivers. Presented are quantitative parameters characterizing the extremity of observed events. The expert assessment of the probability of such combination of events demonstrates that its return period is about 500–1000 years if there is assumption on the stationarity of processes. Taking into account the revealed facts and available assessments of climate changes it can be supposed that the analyzed event rather indicates real changes in the hydrological regime of the region than represents a rare random phenomenon. 相似文献