共查询到20条相似文献，搜索用时 46 毫秒
1.
ON THE VERTICAL DISCRETIZATION OF ATMOSPHERIC MODELS—PART I:EXISTING PROBLEMS,DATA PROCESSING AND CHOICE OF VERTICAL COORDINATE AND BASIS FUNCTIONS 
下载免费PDF全文
下载免费PDF全文 Discussions are carried out on the vertical discretization of current atmospheric models.It ispointed out that there exist problems in the integration of the hydrostatic equation and thecomputation of vertical advection,vertical diffusion and so on.Then some possible ways forsolving or alleviating them are suggested.Finally,the choice of vertical coordinate and basisfunctions is discussed. 相似文献
2.
By utilizing the denser upper-air observations from the Okinawa region and Japanese islands during August 17-23, 1975, the vertical transports of heat and moisture by cumulus convection in the typhoon No. 7507 have been calculated. It is found that there exist a large apparent heat source (Q1) and a moisture sink (Q2) in the southern part of the typhoon at the disturbance, growing and mature stages. The magnitudes of the apparent heat source and moisture sink are rather small, or turn into the apparent heat sink in the northern sector of the typhoon. In the southern part of the typhoon, the total cloud mass flux (Mc) is positive, whereas in the northern part of the typhoon Mc is negative. The above-mentioned distributions of Q1, Q2 and Mc agree well with the major cloud patterns.In the southern part of the typhoon, Q2 is positive because the drying effect is always larger than the evaporative cooling, whereas in the northern part of the typhoon, the opposite case is true because both the drying and evap 相似文献
3.
Vertical profiles of fine and coarse aerosol particles were determined by cascade impaetors at the meteorological tower in Beijing for three days and one night, July 18-23, 1980. Coarse mode aerosols showed a maximum concentration at 47 m when there was an inversion at about 140 m height, and a rather uniform distribution when there was no inversion. This may indicate a two-component origin of coarse particles at the tower site, one being surface dust and the other being tall stack emissions. Fine mode aerosols showed more complex vertical profiles. Median particle size distributions of most metals were bimodat, indicating distinct coarse particle dispersion and fine accumulation mode processes. A chemical thermodynamfc calculation indicates that fine mode Si can result from the reduction of silica to volatile SiO during coal combustion with limited air supply, a process which should release substantial amounts of carbon monoxide to the atmosphere. 相似文献
4.
In numerical weather prediction (NWP), the accuracy of vertical interpolation of the initial data is a problem which is greatly concerned by people. In this paper, we specify vertical distributions of the temperature and the geopotential height fields and examine three interpolation methods, i.e. the Lagrangian polynomial interpolation method (hereafter abbreviated to LP method), the linear interpolation method (LN method) and the local spline interpolation method (LS method) proposed by the author. The examination shows that when the vertical resolution of the initial data is high enough, for example, the number of the given data levels N is 10 or more, all the three methods get good accuracy of interpolation, especially, the LP and the LS methods have very little errors almost tending to zero, while the LN method has a little larger errors than the two formers and the errors at various levels have the same sign. When N is reduced to 5, the LP and the LS methods still have quite good accuracy and simil 相似文献
5.
Two kinds of observational data,fluctuation and mean profile measurements,from a 325 mmeteorological tower in Beijing,China,are used to evaluate local scales of velocity andtemperature for higher heights by flux-gradient mean profiles and eddy-correlation techniques.Acomparison of these methods each other was made in terms of vertical turbulence fluxes formomentum and beat at the same heigbt.The vertical profiles of non-dimensional second moments.such as vertical turbulent fluxes of momentum and heat.velocity and temperature standarddeviations,were derived by local similarity theory.The local similarity relations expressed that thevertical distributions of non-dimensional second moment variables were found to be functions ofz/Λ and z/h in the stable boundary layer and the function of z/Z_i for the convective boundarylayer,where A the local Monin Obukhov(M-O)length.h the height of stable boundary layer andZ_i the height of mixed-layer.These relations are shown to agree well with the observational data. 相似文献
6.
Two schemes for vertical discretization of the model are proposed,one with equal △lnσ andthe other in terms of Tschebyscheff polynomials.It is proved that in adiabatic and inviscid cases ifthe meteorological elements and related physical quantities are continuous in time and in thehorizontal,the total energy and total mass are conserved within a high approximation respectively,and there is a correct conversion between total kinetic and total potential energy.Numericalcomputations show that the schemes both have high accuracy.For example,in integrating thehydrostatic equation the computational errors of geopotential height resulting from the schemes aremuch less than those resulting from EC79 in a-coordinate. 相似文献
7.
The impacts of stratospheric initial conditions and vertical resolution on the stratosphere by raising the model top, refining the vertical resolution, and the assimilation of operationally available observations, including conventional and satellite observations, on continental U.S. winter short-range weather forecasting, were investigated in this study. The initial and predicted wind and temperature profiles were analyzed against conventional observations. Generally, the initial wind and temperature bias profiles were better adjusted when a higher model top and refined vertical resolution were used. Negative impacts were also observed in both the initial wind and temperature profiles, over the lower troposphere. Different from the results by only raising the model top, the assimilation of operationally available observations led to significant improvements in both the troposphere and stratosphere initial conditions when a higher top was used.
Predictions made with the adjusted stratospheric initial conditions and refined vertical resolutions showed generally better forecasting skill. The major improvements caused by raising the model top with refined vertical resolution, as well as those caused by data assimilation, were in both cases located in the tropopause and lower stratosphere. Negative impacts were also observed, in the predicted near surface wind and lower-tropospheric temperature. These negative impacts were related to the uncertainties caused by more stratospheric information, as well as to some physical processes. A case study shows that when we raise the model top, put more vertical layers in stratosphere and apply data assimilation, the precipitation scores can be slightly improved. However, more analysis are needed due to uncertainties brought by data assimilation. 相似文献
8.
In this paper, an equation of the vertical velocity at the top of PBL is derived by use of a PBL model which is based on an analytic and actual form of K. Results show that the vertical velocity is a function of geostrophic vorticity, geostrophic wind speed, Coriolis parameter and the roughness of the ground, thus improving Charney-Eliassen's formula. The order of magnitude of the vertical velocity computed from our equation is in agreement with that from the latter, but more factors affecting the vertical velocity are included. 相似文献
9.
Considering the observational error, the truncation error and the requirements of numerical weather prediction, three formulas for determining the distance between two adjacent stations d1, the observational vertical increment △p1 and the observational time interval △t1 in optimum sense, have been derived. Since they depend on the shortest wavelength concerned and the ratio of maximum observational error to wave amplitude, the results are quite different for different scale systems.For the filtered model the values of d1, △p1,, and △t1 in general come near those required in the MANUAL on the GOS published in 1980 by WMO. But for the primitive equation model the estimated value of △t1 is much less than those required in the filtered model case.Therefore, it is improper to study the fast moving and developing processes of the atmospheric motion only on the basis of the conventional observations. It seems to be necessary to establish an optimum composite observational system including the surface-base 相似文献
10.
The absorption, attenuation, and baekseattering of hailstones with various structures are investigated by the model calculations of four kinds of spherical hailstones: pure ice spheres, liquid water-coated ice spheres, spongy ice-coated ice spheres, and all spongy ice spheres. Alt the results for the wavelength 5,56 cm, including the radar reflectivity factor, absorption factor, and attenuation factor of hailstones with different size distributions are given and discussed in this paper. The possible applications of these characteristics in radar monitoring of hailstones are also discussed, It is shown that in certain conditions, a microwave radiometer simultaneously operating with a radar witt be helpful to the identification of the hail-bearing area. Finally, the possible influence of hailfall area on the accuracy of the measurements of the rainfall distribution by using a radar-radiometer is simply discussed. 相似文献
11.
COMPARISON OF AEROSOL CHARACTERISTICS OVER MAINLAND OF CHINA AND WESTERN PACIFIC AND ITS LONG-RANGE TRANSPORT 下载免费PDF全文
下载免费PDF全文 Wen Yupu Yang Shaojin Yang Yinan Chen Bingru Zhou Mingyu Zheng Yueming Zhang Ziyu Yu Hongjian 《Acta Meteorologica Sinica》1991,5(2):160-170
Based on the aerosol data obtained at Shangdianzi regional background monitoring station together withthe air trajectory analysis,the chemical constituents of the aerosol from the different sources are discussed andcompared with the aerosol samples collected over the western Pacific.The results show that the relative massconcentrations of the crustal and pollutant elements in the aerosol collected over the ocean are higher than thosebeing observed at Shangdianzi in particle size above 4.7 μm and below 0.65μm in diameter.The variationsof the enrichment factors of these elements in marine aerosol with particle size are different from those in shang-dianzi's samples.The former enrichment factors are evidently higher than the latter above 1.1 μm in diameter.On the basis of the comparative research,the long-range transport processes of aerosol particles are discussed. 相似文献
12.
A numerical experiment has been carried out to study the mechanism of cyclogenesis and the development of disturbances. First, an idealized field of temperature and pressure is designed, which is very similar to the actual synoptic situation, consisting of the jet-like zonal circulation with some nonzonal waves superimposed on it. Prediction is made by using a six-level splitting primitive model with the idealized field as an initial one. The results show that if a disturbance like a frontal zone in the lower troposphere is superimposed on the zonal circulation, a frontal cyclone will quickly develop and then gradually become an occluded one. Its life cycle is similar to that of the actual frontal cyclone on the synoptic map. However, if there is a disturbance superimposed on the zonal circulation in the middle troposphere, the cyclone with weaker intensity will be slowly formed near the surface. Finally, if the initial disturbance is located at the high-level, a situation like a cut-off low rather than 相似文献
13.
Using the turbulent statistical form of the vertical vortex diffusion coefficient K2, in the planetary boundary layer (PBL) and Ekman spiral wind profile, the three-dimensional diffusion equation is solved by the numerical method. The influences of vertical shear of both wind direction and wind speed on pollution trajectory and horizontal diffusion parameters σy are numerically analysed. The expressions of both pollution trajectory and σy, including the factor of wind shear, are obtained. The results show that the vertical shear of wind is important among all factors affecting the mesoscale dispersion. Specifically, from neutral to stable atmospheric conditions, vertical shear of wind makes greater contribution to σy than turbulence, thus it is the most important factor. In this paper, we have compared horizontal dispersion pattern with both Pasquill's dispersion pattern considering wind direction shear, and experimental data collected at 9 different sites ranging from 10 to 100 km, and the results show that our dispersion pattern is closer to the experimental values than Pasquill's results, and his correction to shear of wind direction is too large under the stable conditions. 相似文献
14.
STUDYING THE SKY RADIANCE AND DEGREE OF POLARIZATION AND SOUNDING THE OPTICAL CHARACTERISTICS OF ATMOSPHERIC AEROSOL 下载免费PDF全文
下载免费PDF全文 The sky radiance and degree of polarization with multiple scattering process considered were calculated inthis paper by solving vector form radiative transfer equation iteratively. Numerical experiment for simultaneouslyretriving the size distribution (SD) and the complex refractive index (CRI) of aerosol particle was conductedwith the degree of polarization of skylight (DPS) and the library method used. It is shown from the resultsthat the real part of CRI is always sensitive to DPS. But situation is somewhat complicated for the imaginarypart of CRI. Therefore, it is expected that the real part of CRI can be retrieved from DPS and its imaginarypart should be retrieved as the particle is large in size. In this paper, seven sets of DPS measurements on 6 January,1990 in Beijing were given and the optical characteristics of aerosol were retrieved. 相似文献
15.
1 INTRODUCTIONMeteorological factors, especially precipitation,have close links with geological calamities. Accordingto the statistics, more than 70% of the geologicalcalamities in China occur in rainy seasons. Manyresearchers are thus motivated to study … 相似文献
16.
Jin Yi''e 《Acta Meteorologica Sinica》1990,4(1):106-112
A simple method of determining emissivity of surface using Eppley pyrgeometer in situ is presented toevaluate surface temperature exactly.The indicated temperature of radiometer needs corrections for actualsky thermal radiance and for true surface emissivities.Comparisons between radiation temperature andsurface mercury-thermometer temperature at Nagqu,northern Tibet during December 1985—January 1986have shown that their differences are mostly within 2—4℃ 相似文献
17.
In this paper,the local potential of nondivergent flow on beta plane is derived from the motion equa-tion.The conservation principle for vorticity is obtained when the local potential tends to be minimumwith the variational technique.Some other properties st,ch as Lagrangian of vorticity equation,energyetc.are also discussed briefly in the paper. 相似文献
18.
Wang Xingbao 《Acta Meteorologica Sinica》1995,9(4):488-500
Effects of topography on the propagation and development of inertia gravity waves areinvestigated by means of WKBJ method.The equation of wave action conservation is obtained.It isfound that the inertia gravity wave tends to propagate to the higher elevation area,meanwhile theamplitudes of the waves increase.While the inertia gravity waves propagate to a lower elevation area,their amplitudes decrease. 相似文献
19.
Monte-Carlo method is applied to simulate the intensities and degrees of polarization in twilight sky after the eruption of the El Chichon volcano and during the 1977 volcanically quiet period, respectively. The results coincide well with the observations. It is found that the significance of multiple scattering is completely different in these two periods; the background concentration of stratospheric aerosols has probably increased since the 1960's. It is necessary to study the cause of the increase and its impact on climate. 相似文献
20.
By using the low-spectral model simplified from quasi-geostrophic approximation two-levelmodel,we obtained the result that the equivalent barotropic state is an equilibrium state of theatmosphere in that model,and discussed the conditions needed for existing the Rossby wavepossessing the equivalent barotropic structure.And then we derived the oscillation equation reflectingthe phase change of Rossby wave between higher and lower levels from the basic state of equivalentbarotropic stationary Rossby wave,indicating the relations between the change of difference of phaseat higher and lower levels and the disturbance of vertical shear,the amplitude disturbance of the partof waves of stream function and thermal wind stream function on the average level (A′ and B′).It isconcluded that the inter-transformation exists between Rossby waves possessing the equivalentbarotropic and baroclinic structure. 相似文献