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1.
Based on the existing cumulus convective parameterization schemes,a mass flux scheme(MFS)for cumulus convective parameterization has been successfully developed by reference to thework of Chen et al.(1996).The MFS is a comprehensive scheme.In MFS,not only theimportance of the large-scale moisture convergence is taken into account,but also it includes thecumulus updrafts and downdrafts,cumulus-induced subsidence in the environmental air.entrainment,detrainment and evaporation.The interaction between the cumulus and theenvironment is described by using a one-dimensional bulk model.At the same time the schemeincludes the penetrative and shallow convections.The MFS has been successfully incorporated into the regional climate model RegCM2developed by NCAR.The new model has been applied to simulate summer monsoon characteristicsand their variations of heavy rainfall process in the Changjiang-Huaihe River Basins for threemonths from May to July 1991.The results show that the new model can successfully simulate thisrainfall prolonged process.By comparising the model outputs of RegCM2.using the Kuo schemeand the MFS.it is found that the MFS is better in simulating the surface temperature,rainfallposition and amount,and rainfall duration.  相似文献   

2.
By comparison of simulated cumulus convection processes in RegCM2,using the Kuo scheme,the Grell scheme and the mass flux scheme (MFS),it is found that the MFS can simulate thecumulus heating and moistening very well.A series of sensitivity tests show that the parametersfor specifying the conversion coefficient from cloud droplets to raindrops,the turbulententrainment and detrainment rates in updrafts anddowndrafts,and the intensity of thedowndraftshave different degrees of influence upon the cumulus convection.Therefore.it is quite importantfor cumulus parameterization scheme to define these parameters as accurately as possible.  相似文献   

3.
By comparison of simulated cumulus convection processes in RegCM2,using the Kuo scheme,the Grell scheme and the mass flux scheme (MFS),it is found that the MFS can simulate the cumulus heating and moistening very well.A series of sensitivity tests show that the parameters for specifying the conversion coefficient from cloud droplets to raindrops,the turbulent entrainment and detrainment rates in updrafts anddowndrafts,and the intensity of the downdrafts have different degrees of influence upon the cumulus convection.Therefore.it is quite important for cumulus parameterization scheme to define these parameters as accurately as possible.  相似文献   

4.
A 2-D global chemistry-transport model is set up in this paper.The model simulates theatmospheric ozone distributions well with specified dynamical conditions.The analysis of ozonevariation mechanism shows that ozone is chemically in quasi-equilibrium except for the polar nightregion where the variation of ozone concentration is under the control of dynamical processes,thatthe oxygen atoms which produce ozone are mainly provided by the photolysis of O_2 in the upperstratosphere and by the photolysis of NO_2 in the lower stratosphere and the troposphere.and thatthe ozone is destroyed mainly by NO_x:the reactions between NO_x and O_3 and the odd oxygen cyclecontribute 80% to more than 90% of the ozone destruction.  相似文献   

5.
A two-layer primitive equation model is developed in this paper. The capabilities of this model aretested by the use of multiyearly averaged January and July sea surface level pressure fields and windfields which can be diagnosed from the pressure fields. The results show that the ocean surface currentsand undercurrents in the second layer driven by the sea surface wind and the sea surface pressure areclose to the observation. The results are also compared with that of the IAP OGCM and the OSUOGCM.  相似文献   

6.
There is distinct difference in the tangential wind profile between different typhoons in the western North Pacific. At present, only two parameters, maximum wind and radius of maximum wind, are used in NCAR-AFWA bogus for MM5 mesoscale numerical model. As a result, sometimes the outer structure of typhoon cannot be described accurately. The tangential wind profile of NCAR-AFWA bogus is improved by introducing radii of 25.7 m/s and 15.4 m/s, and then the track and intensity of Typhoon Nockten (No.0425) are simulated. The results show that the simulations of track and intensity of typhoon both have been improved by simultaneously introducing the radii in the tangential wind profile of typhoon bogus. At the same time, there is improvement in the gale wind range of the typhoon simulated.  相似文献   

7.
The atmospheric intraseasonal oscillation(ISO)and its interannual variability are simulatedby the atmospheric general circulation model,which was developed at the Institute of AtmosphericPhysics.Two numerical experiments were performed,corresponding to the AMIP-Ⅰ and AMIP-Ⅱsimulations,respectively.The model reasonably reproduces the major aspects of the intraseasonaloscillation,including the propagating property and the seasonal differences in the tropics,thewavenumber structure of ISO in the globe,and the global coincidence in the interannual variationof ISO.Comparison of the results between the two experiments suggests that improvement of theboundary forcing or considering the air-sea interaction may help to improve the simulation on theISO and its interannual variability.  相似文献   

8.
n this paper,using NCEP dataset and the Wei's method,we calculate the exchange of massacross the thermal tropopause during 1998 over the Tibetan Plateau and its surroundings.Theresults indicate that:(1)There is strong air transport from troposphere to stratosphere in summerover the Tibetan Plateau and its surroundings.The air transport reaches the summit in midsummerwith three large value centers among which the Bay of Bengal is the largest and the other two largecenters lie in the east and northwest of the Tibetan Plateau,respectively.In May and October thecross-tropopause mass exchange reaches balance.In other months the mass transport is fromstratosphere to troposphere.(2)As far as the cross-tropopause mass exchange from June toSeptember in 1998 is concerned,the net mass transport is 13.7×10~(18) kg from troposphere tostratosphere,So the area from Tibetan Plateau to the Bay of Bengal is a channel through which airmass gets into stratosphere from troposphere.  相似文献   

9.
Based on the existing land-surface schemes and models,an improved Land-surface ProcessModel(LPM-ZD)has been developed.It has the following major characteristics:(1)Thecombination of physical equations and empirical analytical formulae are used to construct thegoverning equations of soil temperature and moisture.Higher resolution of model level andphysical equations are adopted for the upper soil layers,and for the lower soil layers,lowerresolution of model level is adopted and empirical analytical formulae are used.(2)In land surfacehydrological process,the sub-grid distribution of rainfall and its effects are taken into account.(3)A simple snow cover submodel has been used,which includes effects of snow cover on soilthermodynamics and hydrology,as well as albedo.By use of this model and three groups of point observation data,a series of“off-line”testshave been carried out.The simulation results indicate that land-surface process model has goodperformance and can well simulate diurnal and seasonal variation of land surface processes for manykinds of land surface covers(forest,grass,crops and desert)in different climate zone.The resultssimulated by the model are consistent with the observations.Later,by use of one group ofobservation data and the model,a series of sensitivity experiments have been done.It is shownthat the model is much sensitive to some parameters,such as initial soil moisture,vegetationphysical parameters as well as the proportion of the grid covered with rain.Therefore it is muchimportant for land-surface process model to define these parameters as accurately as possible.  相似文献   

10.
Based on the existing land-surface schemes and models,an improved Land-surface Process Model(LPM-ZD)has been developed.It has the following major characteristics:(1)The combination of physical equations and empirical analytical formulae are used to construct the governing equations of soil temperature and moisture.Higher resolution of model level and physical equations are adopted for the upper soil layers,and for the lower soil layers,lower resolution of model level is adopted and empirical analytical formulae are used.(2)In land surface hydrological process,the sub-grid distribution of rainfall and its effects are taken into account.(3)A simple snow cover submodel has been used,which includes effects of snow cover on soil thermodynamics and hydrology,as well as albedo.By use of this model and three groups of point observation data,a series of "off-line" tests have been carried out.The simulation results indicate that land-surface process model has good performance and can well simulate diurnal and seasonal variation of land surface processes for many kinds of land surface covers(forest,grass,crops and desert) in different climate zone.The results simulated by the model are consistent with the observations.Later,by use of one group of observation data and the model,a series of sensitivity experiments have been done.It is shown that the model is much sensitive to some parameters,such as initial soil moisture,vegetation physical parameters as well as the proportion of the grid covered with rain.Therefore it is much important for land-surface process model to define these parameters as accurately as possible.  相似文献   

11.
A series of data assimilation and forecast test have been carried out with a hemispheric spectralmodel(T42L9H).It is found that the numerical scheme for determining hemispheric initial wind isimportant to data assimilation and forecast.An inappropriate scheme may cause computationalsources of divergence near the equator,which are responsible for the spurious strong precipitationand corresponding latent heat release.Obviously,this problem differs from either thehemispheric/global domain effect or the tropical data effect pointed by Dalley et al.(1981).Basedon the previous studies,the new scheme of divergence and vorticity correction is presented,andthe difference with other schemes and its effects on the data assimilation are discussed against thecontrol test.Preliminary tests have shown that the new divergence correction scheme proposed in thispaper may be a preferable choice to overcome the initial computational errors in the hemisphericdata assimilation.  相似文献   

12.
A coupled regional air-sea model is developed by using the regional climate model (P-σ RCM)and the regional ocean model (POM),which is used to simulate East Asian monsoon and oceanicelements in East Asian coastal waters.The simulated surface layer oceanic elements are basicallyconsistent with the reality and can reflect the interaction between the monsoon and the surfacelayer currents.The great difference with the reality is “cold drift” of the simulated surfacetemperature.The coupled model has certain ability to simulate the atmosphere geopotential heightfields,precipitation and low-level southwest wind from May to August in 1998.It can display theprocess of summer monsoon onset during the third dekad of May and the evolution features afterthe onset.The differences between the simulation results of the coupled model and that of thesingle P-a RCM are shown mainly in the low-level atmosphere and the model internal regions.  相似文献   

13.
SUN-PHOTOMETER CALIBRATION AND ITS APPLICATION   总被引：6，自引：1，他引：6       下载免费PDF全文
Sun-photometer has been widely used to investigate various optical properties of the atmosphere.In order to derivean accurate atmospheric optical depth,great care in the sun-photometer calibration is required.In this paper,the fea-ture of a new sun-photometer is described.Calibration results based on the Langley method at Mt.Huangshan are re-ported.Effect of the atmospheric instability on retrieving the calibration values is discussed and errors in calibration atMt.Huangshan due to temporal variation of aerosol concentration are estimated.It is shown that the calibratedsun-photometer can be used to derive the atmospheric optical depth to an accuracy of 5%.As one of its applications,examples of determination of turbidity parameters and columnar aerosol size distribution are presented.  相似文献   

14.
The Land-surface Process Model(LPM-ZD)has been successfully coupled with the regionalclimate model RegCM2 of NCAR.Then thus-obtained coupled model(CRegCM)has been appliedto simulate the climate characteristics of heavy rain in middle and East China for three months fromMay to July 1991.and compared with model output of NCAR-RegCM2 using BATS as land-surface process scheme,abbreviated as NRegCM.The results show that CRegCM has good abilityand performance.CRegCM successfully simulates the extreme precipitation event and thesimulations of CRegCM for surface temperature and some physical variables related to land surfaceprocess are more reasonable than those of NRegCM.  相似文献   

15.
In this paper,the development of the studies on the weather-yield simulation and forecasting model inChina is briefly reviewed,and the main features of the current development stage are presented.Moreover,through examples the technical characters,approaches and experimental results are detailedly described anddiscussed of several major statistical forecasting models,dynamic crop growth simulation and the satelliteremote sensing methods to estimate crop yield.Finally,the line of further development and the applied fieldare pointed out.At the present time,in particular,using the above-mentioned modelling techniques to simu-late and evaluate the possible impact of climatic variation on agricultural production and further on man'ssurvival and activities are of a very practical significance as well as socioeconomic benefits.  相似文献   

16.
In this paper,by using measurements in micrometeorology and radiation balance in the surface layer(Yamanouchiet al.,1981;Wada et al.,1981;Ishikawa et al.,1982;Ohata et al.,1983),we have analyzed the diurnal and annual varia-tion characteristics of radiation balance in spring,summer,autumn and winter,and calculated the momentum flux andsensible heat flux with the aerodynamic method and profile gradient alternate method in different seasons.We have alsoobtained the diurnal variation characters of the latent heat flux from the equation for energy balance.The results fromthe calculation are compared.Finally,the relationship between the turbulent heat and momentum exchange coefficientand the diurnal variation of the Richardson number is discussed.  相似文献   

17.
In this study the results from a boundary layer experiment,conducted in autumn 1991 over a flat,build-up urbanarea in Southeast Sofia,together with some models for mixed layer growth rates are used to investigate the layered struc-ture of the vertical atmospheric stability distribution in the Sofia Valley.Lidar measurements of aerosol layer heightsand morning boundary layer development are combined with surface eddy correlation measurements of kinematic heatand moisture fluxes,profiles of temperature and humidity,wind speed and wind direction.A diagnostic method is pres-ented for determining vertical lapse rates using surface meteorological measurements and lidar returns observed duringthe transition from nighttime stable stratification to daytime convective boundary layer after the sunrise.  相似文献   

18.
The sustained rainfall process on May 13-22, 2004 was one of the pre-summer rainy periods in the south of China. It was related with the genesis and development of a SW monsoon surge over the Bay of Bengal. From the synoptic analysis it is found that the genesis and development of the SW monsoon surge may be divided approximately into the initial, developing and decaying stages. During the rainfall the Southern Hemisphere cross-equatorial flow over the Indian Ocean plays a triggering role.  相似文献   

19.
ＳＨＯＲＴ－ＴＥＲＭＣＬＩＭＡＴＥＣＨＡＮＧＥＡＮＤＩＴＳＣＡＵＳＥＡＮＤＣＬＩＭＡＴＥＰＲＥＤＩＣＴＩＯＮＩＮＣＨＩＮＡ￥ＷｅｉＦｅｎｇｙｉｎｇ（魏凤英）（ＩｎｓｔｉｔｕｔｅｏｆＳｙｎｏｐｔｉｃａｎｄＤｙｎａｍｉｃＭｅｔｅｏｒｏｌｏｇｙ．）Ｂｅｉｊ...  相似文献   

20.
The limited area analysis and forecast system(LAFS)was developed and has been put intooperational use at National Meteorological Center since January 1991.This system can be regardedas a branch system attached to the global assimilation and medium-range forecast system which isbased on a spectral model T42L9.The main advancements as an upgrade operational system are asfollows:the use of a regional fine mesh optimum interpolation(OI)analysis scheme:the realiza-tion of the nonlinear normal mode initialization for the regional model:the development of a 15L-spherical grid primitive equation model(with real topography and enstrophy conservation)and itsnesting forecast with the spectral model T42L9.  相似文献   

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