Abstract:In this paper, the fluctuated radar signals caused by precipitation have been simulated. In order to obtaiⁿ nearly real radar signals, a certain quantity of homogeneous white noise is put in.The purpose of the simulated test, based on the fluctuated signals measured by a conventional radar, is to verify the following two points which are closely related to turbulence characteristics: (1) whether the value of the video-frequency-fluctuation-speetrum variance δ_F² is approximately twice as much as that of the Doppler frequency spectrum variance δ_f² (i. e. δ_F²=2δ_f²), (2) whether the sum of the fluctuated signals from two adjacent pulse volumes (V₁ and V₂) can be substituted for the fluctuated signal of the bigger volume V₃ which equals to V₁+V₂ and be used to evaluate the fluctuated spectrum variance of volumeThe result of the simulation shows that the two points mentioned above are essentially practical. In addition, errors in the simulation are also anal ysed.

Abstract:The tropical circulation induced by the nouthern-hemisphere winter tropical pacific SST warm anomaly and its quasi-biweekly oscillation anomaly are simulatcd in terms of the p-σ mixed coordinate five layered primitive equation global band model with the surface temperature governed by the heat balance euqation. The results are summarized as follows: The SST warm anomaly can produce several rainfall centers in the low latitude convergence zone that are about 25-30 longitudes apart. This phenomenon may well be caused by the westward dissipation of the disturbance energy in the anomalous warmth while the phase velocity of the disturbance is eastward. The greater the SST warm anomaly is, the more intense are the resulting precipitation, the cross equatorial upper and low level streams, the westerlies in the northern hemisphere subtropics, the anti-Walker circulation on the west side of the disturbance and the anomalous upper-level easterlies, and the usual Walker circulation on the east side and the anomalous upper-level westerlies. When the SST warm anomaly is observed in the eastern Pacific, the resulting anomalies are all found farther east and are generally weak in strength. With the decay of the quasi biweekly oscillation,the difference between the anomalies of circulation and rainfall produced by different SST warm anomalies are also small.

Abstract:Theoretical expressions are derived for the distribution function of as well as the mathematical expectation and variance of the total amount of precipitation and the daily maximum precipitation occurring in an N-day period based on the one-order Markov Chain and the Gamma probability model of daily rainfall. By using the data from five representative stations over China, we find that the model has a good fitting effect and can thus be used to estimate the probability of the total amount of precipitation and the daily maximum precipitation in any N-day period.

Abstract:contrast experiments are performed by diagnostic analysis on the effect of the southern hemisphere cold air activity on the northernhemisphere summer monsoon in terms of Kuo-Qian p-σ incorporated coordinate five-layered primitive equation spheric band model.Emphasis is laid on analysis of the different responses of the flow, pressure and rainfall fields as well as the dibatic heating in the Asian monsoon area, especially in East Asia, to the presence and absence of the cold air activity in the Australian area .Results suggest that the Australian cold air can make the East Asian summer monsoon enhanced and move northward, but the Indian monsoon may become weakened or interrupted. In the process the meridional wind disturbance exhibits a south north pro pagation with a time lag of ten to fifteen days.

Abstract:A dynamic analysis is made of the occurrence of a low-level jet stream with emphasis placed on the circulation structure in the jet region as well as the effect of the cumulus convection on its formation and evolution. It is found that a Couple of transversal ageostrophic secondary circulations in the low-level jet region plays a significant dynamic role. The static instability field coupling caused by the strong dispersive Iowlevle jet and the cumulus convection induces unstable mesoseale gravitational inertia waves which trigger the development of the jet stream and secondary circulation through Wave-CISK mechanism. Both the ageostrophie characteristics and the secondary circulation in the evolution of the jet are the products of the development of the gravitational inertia waves.

Abstract:The precipitation fluctuation in convective clouds was further observed by radar in June 1984. Through the maximum entro Py method the radar data are analysed, showing that precipitation in warm convective clouds has 0nly one fluctuation in the period of about 20 minutes while that in the cold convective clouds comprises two oscillations with the bigger one in a 20-30 minute period and the smaller in an 11-15 period. The conclusions given in this, paper need more observational data to support.

Abstract:A low resolution global circulation spectrum model, using primitive equations, which can be appliedto climate simulations and sensitivity tests is described in this paper. The model has three levels in its vertical direction and a spherical harmonics representation with a ten-wave rhomboidal truncation in its horizontal direction.Some physical processes, such as radiation,convectiye adjustment, large-scale condensation and surface fluxes are also included. Global distribution of climates for January and July are simulated by using the actual zonal average field as the initial field. The simulated monsoon rain belt is especially close to the observation in the model. Therefore,the model is useful in the investigation of the climatic changes and the formation and maintenence mechanism of monsoon in China.

Abstract:Mainly based on the theory on apparent temperature initiated by the famous American biometeorologist R.G.Steadman, the monthly mean apparent temperatures in the four seasons (Jan., April, Jul. and Oct.) have been calculated and their distributions plotted herein. Preliminary conclusions are thus reached by analysis on the synoptic and climatic features in different climatic regions over China and their effects on human activities.

Abstract:The SO₂ instantaneous Concentration in the Dachangdistrict of Nanjing under neutral conditions is calculated by using the Gaussian (normal) model, the Egan model, the SCIM model and the GCEM model. The re suits from calculation are compared with the observational data. It is found that the GCEM model for which the terms of topography revision and chemical decay have been taken into account works well and its calculated values are consistent with recorded concentrations.

Abstract:In this paper errors from the temperature measurement on the 50m meteorological tower in the Nanjing Institute of Meteorology are analysed. It is pointed out that the error is less than 0.1℃, quite coincident with the appraisal granted by the state Meteorological Administration.

Abstract:In this paper the parameterization used by K. Fraedrich is adopted to discuss the characteristics in the equilibrium state of the zerodimensional model, and thereafter the stochastic model for the global temperature changes is reviewed and revised. And then the revised model is checked with the 1881-1981 northern hemisphere temperature anomaly series.

Abstract:Chao’s cloud model is introduced into the large scale potential vorticity equation in this paper. The apparent potential vorticity source in the ITCZ area is calculated by using FGGEⅢ_b data and its distribution analysed. Results show that Chao’s model can well represent the vertical transport of potential vorticity due to cumulus convection.