共查询到20条相似文献，搜索用时 15 毫秒
1.
The favourable synoptic situation and climate background for a sandstorm process,which occurred in theperiod 9—16 April 1988,have been studied through analyzing weather maps,meteorological elements,satellitecloud pictures and sandstorm trajectories.The sand dust origin area,the directions and the paths of sanddust transport,and the extent the sand dust reached are also investigated.The results of measurments andanalysis indicate that the concentration of sand dust particles is 10 times greater than the normal.It is also shownthat the elements in the sand dust are lithophylic and come from natural source through the chemical composi-tion analysis of the sand dust,so that the sand dust has not been polluted by human activities. 相似文献
2.
Downburst is a very dangerous weather phenomenon for aeroplane taking off or landing. Inorder to understand the initial formation and evolution of downburst and to study the effects of at-mospheric environment condition and the microstructure of cloud-precipitation particles on thedownburst development processes, we have designed and carried out a modeling scheme by makinguse of our own non-hydrostatic compressible mesoscale-γ model including necessary cloud-precipi-tation processes. The initial conditions of temperature, humidity and wind are from an observationcase in which the downburst occurred. The results of computations demonstrate the evolution ofdownburst and show the variation of various environmental and microphysical parameters. Some ofthe mechanisms about the downburst occurrence have been obtained. Computation results mayhelp airport forecasters to determine the occurrence of downburst better. 相似文献
3.
A nonlinear steady-state baroclinic primitive-equation numerical model of atmospheric forced stationarywaves is used to investigate the tropics-extratropics interactions.Newtonian cooling,Rayleigh friction andbiharmonic horizontal diffusion are included in the model.The Eliassen-Palm (EP) cross-section and three-dimensional wave activity flux,which was derived by Plumb (1985) for linear quasi-geostrophic stationarywaves on a zonal flow,are used as diagnostics for the vertical and horizontal propagation of the waves.Results of the numerical experiments and diagnostics analyses suggest that the extratropical influenceon the tropical large-scale motion is important.The mid-latitude orographic forcing,especially of the Qing-hai-Xizang Plateau,and the extratropical thermal forcing make substantial contribution to the main-tenance of the cyclonic circulation over the eastern tropical and subtropical Pacific as well as the inversecirculation over the western Pacific in the upper troposphere.In addition,the longitudinal variation ofdiabatic heating in tropics has a significant influence on the wintertime stationary waves at higher latitudes. 相似文献
4.
A three-dimensional fog model,suitable for precipitous and complex terrain,is designed contain-ing four prognostic variables—wind speed,potential temperature,specific humidity and mixing ratioof liquid water.The model considers turbulent exchange,the long-wave radiation on the ground sur-face and in the air.the short-wave solar radiation,the evaporation and condensation of moisture andthe surface heat budget and so on.In order to make the model run steadily on precipitous and complexterrain,we have improved the method of calculating horizontal pressure gradient force in the terraincoordinate system.The results coincide on the whole with the actual situation. 相似文献
5.
王会军 《Acta Meteorologica Sinica》1997,(1)
The major advances and achievements of recent studies on monsoon simulation are reviewed.Four aspects are included in the paper and they are simulation of general feature and seasonal tointerannual variation of monsoon.simulation of monsoon and ENSO relations,paleo-monsoonsimulation,and the predictability study of monsoon and monsoon climate.Concluding remarks aremade in the last section. 相似文献
6.
Zhao Shixiong 《Acta Meteorologica Sinica》1988,2(3):394-403
Five hailstones from two severe storms which occurred in the Qinghai area on 23 July and 6 August,1983 have been examined on their deuterium content and crystal structures,and an absolute temperaturescale against deuterium values is discussed.The deuterium concentration on 23 July had values rangingfrom—65.8 to—76.6‰ and on 6 August from—6.1 to—58.6‰,which correspond to the ambient tempera-tures of forming hailstones in the range—18—-23℃ (altitude 7.7—8.6km) and -1.3-27℃ (5.4-9.0 km),respectively.The hailstone embryos are of a type of conical graupel.The analysis of deuteriumvalues indicates that the graupel embryos were formed in the temperature ranges-16.8—-19.5℃(on 23July) and -11.8—-20℃ (on 6 August).It is found that hailstones grew at the middle or upper part ofthe cloud:some grew in the updraft on 23 July and some grew in an up and down motion on 6 August.In this paper,the updraft is calculated by two methods and the trajectory of hailstones is also discussed. 相似文献
7.
The water balance in C'hina is studied in this paper, which follows the papers on the radiation balance and the heat balance in China. Using the data from more than 200 meteorological stations for 1961-1970 and about 200 hydrometric stations bcforc1972, we, through the equation of water balance, have calculated the monthly and annual amounts of precipitation, evaporation, run-off and soil water variation. The water balance and the hydroclimatological characteristics of China arc given. 相似文献
8.
In this paper, the time-space variations of pH and electric conductivity are analyzed for anacid rainstorm during 10-11 August 1984 in Changchun, and the relationship between the pHvalue, meteorological factors, and microphysical characteristics of raindrops are discussed. In addition,the chemical composition of precipitation is also dealt with. 相似文献
9.
10.
ＡＤＶＡＮＣＥＳＩＮＳＴＵＤＹＯＦＩＮＴＥＲＡＣＴＩＯＮＳＡＳＳＯＣＩＡＴＥＤＷＩＴＨＲＡＩＮＳＴＯＲＭ￥ＭａＳｎｕｆｅｎ（马淑芬）（ＩｎｓｔｉｔｕｔｅｏｆＳｙｎｏｐｔｉｃａｎｄＤｙｎａｍｉｃＭｅｔｅｏｒｏｌｏｇｙ）Ｂｅｉｊｉｎｇ１０００８１ａｎｄＤ... 相似文献
11.
1 INTRODUCTIONLightning is a phenomenon of atmosphericelectricity with convective storms. Since the 1960’s, itscharacteristics during weather processes of torrentialrain, hails and tornadoes have been widely studied anda lot of attempts made to probe into the mechanismsresponsible for the formation of lightning[1], giving riseto two theories explaining the lightning genesis, fromthe points of convection and ice-phase precipitation,respectively. In addition, some studies[2-9] show, fromvar… 相似文献
12.
《大气科学进展》1986,(1)
In this paper, a second-order model is proposed for the study of the evolution of the nocturnal boundary layer (NBL). The model is tested against the Wangara data on atmospheric boundary layer. The computer results show that the model can simulate some important characters observed in the NBL, and that a kind of sudden change may occur in the developing process of NBL. 相似文献
13.
By using a P-σ incorporated coordinate five-layer primitive equation spherical band model with surfacetemperature controlled by the heat balance equation,a simulation is done of disturbance formation in ananomalously warm SST area and of the quasi-biweekly oscillation(QBWO)of the disturbance,and associatedrainfall and SST with SST being 1/3 period of oscillational phase ahead of rainfall.The study shows that theoscillation is produced by cloud-radiation interaction.Initial anomalously warm SST in the mid-western Pa-cific causes stronger oscillation than in the eastern.Hence the oscillation gets attenuated during the eastwardmovement of the disturbance. 相似文献
14.
A possible mechanism is put forward in this paper for El Nino events from the viewpoint of plate tec-tonics and oceanic geology.A number of the data are cited to illustrate the views that sea-bottom volcanic ac-tivities and hot springs may cause El Nino events. 相似文献
15.
Based on turbulence theory,a 1.5-order closure turbulence model is established.The model incorporating with theground surface energy budget equation is constructed by means of a vertical one-dimensional(1-D)40-levelgrid-mesh.The numerical results reveal the 24-h evolution of the clear planetary boundary layer comparing with theWangara boundary layer data of days 33—34.The model also takes into account some physical processes of radiativetransfer and baroclinicity,revealing some important characteristics observed in the boundary layer,especially for theevolution of the mixed layer and low-level jet.The calculated results are in good agreement with the observational data.On the other hand,we also run the high-resolution model of the planetary boundary layer in the Mesoscale Model Ver-sion 4(MM4)with the same physical processes and initial conditions.The results show that the high-resolution modelcan not reveal those important characteristics as the 1.5-order closure model did.In general,it is shown that the 1.5-or-der closure turbulence model based on turbulence theory is better in rationality and reality. 相似文献
16.
In order to improve the accuracy of the rainfall measurement, a radar-radiometer system has been devel-oped. It could be used to measure the distribution of the rainfall intensity aLld the variation of area rainfall.In field experiment, the accuracy of the rainfall measurement was imporved. In this paper, the error of rainfallmeasurement by radar will be evaluated and the methods to improve the accuracy of the rainfall measurementwill be discussed. 相似文献
17.
Results of our aerosol study, performed during 1983-1984 in Beijing, demonstrate that ambient carbonaceous aerosols are derived mainly from coal combustion. Different SO, oxidation processes have been observed in summer and winter. The winter sulfate appears to be produced locally and associated with products of incomplete combustion. 相似文献
18.
Orographic effects on monthly-and seasonal-scale low frequency oscillation are investiged in terms of a five-level global spectral model with a triangle truncation at wavenumber 10 that contains relatively full physical parameterization, followed by analysis and comparison of the lowpass filtered data separately obtained from models with and without orography. Results show that remarkable seasonal characteristics are displayed in the orographic forcing-generated low frequency wavetrain on monthly and seasonal scales. It is found that the Northern Hemisphere summer orography-produced tropical heating acts as source of the low-frequency wavetrain for both hemispheres. Besides, the simulations indicate that the orographic wavetrain perturbation can give rise to the anomaly in the equatorial zonal flow, whose transient forcing will cause a new wavetrain in the Southern Hemisphere, thus completing the cross-equatorial propagation of the northern wave in interhemispheric action. 相似文献
19.
THE SENSITIVITY TEST STUDY OF AIR-SEA SURFACE FLUX MODEL 总被引：2，自引：0，他引：2
In this article, a sensitivity test of air-sea surface flux model was carried out with the field observation data of Project “South China Sea Air-Sea Flux Measurement in 2000”. The results show that sensible heat fluxes are sensitive to observation errors, increasing the error of model calculation; In contrast, the latent heat flux and momentum flux are not as sensitive to observation errors as the sensible heat, and their calculated results are reliable. The test result also verifies… 相似文献
20.
Typhoon Maggie (1999) interacted with another tropical depression system and moved along a
west-southwest track that is somewhat abnormal during its pre-landing stage. Two numerical experiments are
carried out in this paper to study the effect of the interaction on the track of typhoon Maggie using the mesoscale
numerical weather prediction model system with a tropical cyclone bogusing scheme developed by Center for
Coastal and Atmospheric Research, the Hong Kong University of Science and Technology. Results show that the
cyclone system interacting with Maggie is the main factor for the abnormal track of Maggie. 相似文献