Abstract:

Abstract:The factors of the generation and development of the mesoscale and Subsynoptical Scale Systems are Studied. Numerical experiments show that the interaction between the circulation of the typhoon outer region and middle latitude synoptical system can trigger off the local disturbance and result in the formation of the cloud cluster and rain belt and the large topographic forcing played an importantrole. The effect of the tropical cyclones and its lifting of the topographic convengence can cause mesoscale disturbance, propagating in the way such as gravity wave.

Abstract:Two three-dimensional sonic thermo-anemometer probes were used to measure velocities and temperatures above and within a pine forest near Chongqing city,Sichuan Province, in order to comprehend mass and energy exchange between atmosphere and forest. The turbulent fluxes of momentum and heat, and statistics and spectra of wind speed fluctuations were calculated from the digital data sampled at rate of both 1s~(-1) and 11s~(-1) , using eddy correlation and FFT method. The results show that above the canopy kinetic momentum was transported downwards, while within the canopy it was transported upwards. Within the canopy mean skewness of u was positive and that of w negative. Above the canopy both the dimensionless standard deviation of u and w and dimensionless turbulence, dissipation rate were functions of local Monin-Obukhov length, while within the canopy those variables did not show the correlations. The "—2/3" power rules, however, were existed at the inertial subrange of power spectra of wind speed either above the canopy or within it.

Abstract:The precipitation within a return current process over Northern China in May 24—25 1991 is analysed. It is considered that:(1) The structure of the return current process precipition, NE cold flow at low level and SW warm and wet flow above, form the warm front precipitation cloud system in favour of the weather modification cloud seeding; (2) The precipitation enhancement is closely related with the cold air action in the boundary layer; (3) The deep inversion layer is actually the transitional level of NE and SW wind. The vertical wind shear above and below the inversion layer is very strong. So that the Richardson number is less than 1.0 within all the layers,and it is a mechanism of precipitation enhancement.

Abstract:Based on observations and physical parameters calculated with a limited-area numerical prediction model,an analysis of a severe black storm on May 5,1993 is made. The results show that the temperature variation gradient,down-momentum and topography played important roles. The distribution of physical parameters,the formation conditions of the black storm and some criterions are given.

Abstract:The continentalities for Fujian Province with three continentality indices ,i. e. annual range of temperature (K index) ,daily range of temperature (T_D index),and dacade range of temperatureprecipitatition variability (L index), are calculated. The results show that the continentalities with the new index—L index—are more fit in with the climate in Fujian Province. The continentalities of the other provincial capitals in China are also calculated with three continentalily indices.

Abstract:A test simulating errors that a maxmum thermometer contracts With cold is made. The results show that the errors ranged from 0. 5 to 1.0℃. And anerror correction diagram is given.

Abstract:Statistical analysis shows that the frequency and fall of nocturnal heavy rains in Henan Province are both 21.6% more than that of the daytime ones,and the area of nocturnal heavy rainfall is 86. 6% larger than that of the daytime ones. The analysis also shows that much nocturnal rains would relate to thermodynamic ,dynamic and topographic factors.

Abstract:Serious drought occured in the central area of Xizang Autonomous Region in the early summer of 1992. Analyses show that the main circulation backgrounds are as the following. The subtropical high laid further south ,while its seasonal movement northward was much later. The circulation over the Qinghai-Xizang Plateau adjusted later from spring to summer. The India monsoon low deepened eruptively later, and its intensity was weaker. When the south Asia high first reached the Qihai-Xizang Plateau, it's delayed. The system of shear lines was weaker and laid to the north.

Abstract:Based on 184 cerebral accidents in Zhejiang Provincial People's Hospital and the meteorological data from 1985 to 1989 ,the relationship between cerebral accidents and weather processes is obtained with methods of statistical and composite analysis and from dynamic point of view. A conception model of forecasting the periods during which more cerebral, accidents would occur is given.