Vol.1, NO.2, 1990

Display Method:
The Meso– and Small–Scale Structure and Potential for Cloud Seeding of Wintertime Snowfall in the Zhungeer Basin
1990, 1(2): 113-122.
In this paper, the radar echoes, intensive soundings, microphysical observations both on ground and in clouds of four precipitation processes in winter of 1984 and the data obtained from aircraft reports in several processes in 1983 are analysed. It is shown that the meso– and small–scale systems play a great role in the precipitation processes. Snowband radar echoes can be divided into two kinds, orographic snowband and systematic snowband. The structure, evolution characteristics, formation mechanisms and the potential for artificial seeding of various types of snowbands in the Zhungeer Basin are also discussed. It is indicated that the snowbands which are produced from dynamical action such as shallow convection, waves and orographic lifting are favorable to be seeded, and that stratocumulus without disturbance or with weak natural seeding of cirri aloft is also suitable for seeding.
Numerical Experiments of Poisson Equation Zero-Boundary with Dual-CPU Parallel Algorithm
1990, 1(2): 123-134.
In this paper, Liebmann method (point iterative) and Local Green Function method (local point iterative) which are usually used in traditional atmospheric/oceanic calculating problems are modified to parallel algorithms adapting to the dual-CPU in IBM-4381 (P03) to solve the Poisson equation for zero-boundary value. The numerical experimental results show that the calculation speed of parallel algorithm is 1.8 or 1.9 times as much as serial algorithm for the same calculating problems. However, when expanding the areas, parallel iterative speed of Local Green Function can reach 2.8 time which exceeds the best speedup (1.7 times for P01) declared by IBM Company. The paper also points out that the data array can be shared by the IBM-4381 (P03) CPU when running parallel calculations
The Comparison Among Several ω–diagnostic Models
1990, 1(2): 315-141.
In this paper, three models which are used to solve theω–field are discussed respectively. The model A is a multi-layer nonlinearω–diagnostic models, model B is a diabatic one and model C is a meso– scale one. They are applied to diagnose a mei-yu front heavy rain process. The differences from each other are analysed. The results show that the model C or model A is better for diagnosing the mesoscaleω field and the difference between twoω fields obtained from the two models is small. Model B is not generally used, but it can be used if the precision requirements are not high in order to save the calculation amount
A Numerical Experiment of Cloud Seeding in Cumulonimbus
1990, 1(2): 142-152.
A Cumulonimbus cloud with moderate intensity and a warm cloud base has been simulated by sing a dual-parameter cumulonimbus cloud model in the rainy season in Fujian. It is shown that the cloud precipitation process has two phases, the first one is a warm-rain process and the second with ice phase process. A series of numerical experiments of cloud seeding show that iceseeding or large droplet seeding cloud enhance the precipitation in the second phase. The effect of precipitation enhancement is concerned with the seeding pattern, the maximum can reach 24% of the total precipitation. In this paper, the mechanism of precipitation enhancement is also discussed.
A Case Study of Mesoscale Systems for A Heavy Rain Storm
1990, 1(2): 153-161.
Three types of mesoscale systems developed within 24 hours and caused heavy rainfall of more than 200 mm in a large domain and 469 mm in some local districts of Beijing. Tianjin and Tangshan area during July 29—30, 1975 are presented resectively. They are meso–βscale complex cell, rainbands and meso– scale vortex. In this paper, the features of movement, propagation, development of radar echoes of precipitation and ambient field associated with these systems are analysed. Also, the thermodynamical mechanisms responsible for the systems are briefly discussed
The Observations of the Huanghai Sea, Bohai Sea and the Sea of Japan Highs and the Heavy Rain in North China Summer
1990, 1(2): 162-168.
In this paper, utilizing day-to-day 500 hPa circulation charts during June–August from 1966 to 1987, the high processes occurred in the region of 30o—50oN, 110o—140oE have been classified into five patterns in light of their forming properties. They are westerlies high, plateau high, subtropical high, the combinative pattern of westerlies high with subtropical high and the combinative pattern of plateau high with subtropical high. The climatic characteristics of the temporal and geographical distributions for the above five patterns have also been analysed. It is shown that the heavy rain weather processes occurred in north China, especially in the east of north China and in the south of northeast China are in close relatiopship with these stable high situations
A Preliminary Study of 3—5 Year Cycle over 500 hPa Height Field in the Northern Hemisphere
1990, 1(2): 169-176.
In the paper, the time series of 500 hPa height departure field from Jannary 1951 to December 1986 are calculated by using a band-pass filter at all grid points in the northern Hemisphere. The preliminary results are as follows: ① There exists a 3—5 year cycle for 500 hPa height field in the northern Hemisphere. The relative variance are over 30% in the northern Hemisphere and 50% to the south of 35oN latitude. The maximun relative variances in the Pacific, Atlantic and Eurasia low latitute area are more than 70%. ② The 3—5 year cycle is provided with more obvious construction of wavetrain than wallace’s teleconnection types. The atmospheric encrgy is transferred by dispersing from low latitude to high latitude along ray path of the wavetrains. ③ From the filtered 500 hPa height departure field during 1982/1983 El Nino event, it is found that in response of atmospheric circulation to the tropical Pacific SST anomaly forcing, there may be another path, in addition to the PNA teleconnection type.
Numerical Simulation of the Wind Field over the Beilun-Zhenhai Area
1990, 1(2): 177-184.
A three-dimensional diagnostic model by Mark A Yocke is mainly introduced in this paper. Using the model, the wind fields over the Beilun-Zhenhai area are simulated. As far as the grid length and boundary condition selected is concerned, the simulative results are conformed with the observations
The Latest Test Results of Photosynthetically Active Radiation
1990, 1(2): 185-190.
In light of the long term continuous automatic synchronous observations of global solar radiation (Q) and the photosynthetically active radiation (QPAR) during the growth seasons in Chengdu, Kuming and Guangzhou, it is found that the QPAR/Q ratio based on hourly accumulative radiation is almost a constant and that the season, cloud amount and diurnal variation of sun’s altitude have not any obvious influence on the ratio. This result is consistent with the previous research conclusion drawn from that in the North China Plain. It seems that the ratio would increase with the latitude getting low
Raindrop Particle Size Distribution in the Lower Troposphere
1990, 1(2): 191-198.
In the Paper, Γ–distribution [n(D)=ADea-λD] parameters (A, a, λ) are obtained by the ratio k1=D1/D2, k2=D2/D3 and linear regression method, where D1, D2 and D3 are diameters for average, root mean square and root mean cube, respectively. The statistical data analysis of raindrop size distribution measured with OAP–2D–P show that the parameter 1 is usually close to 2 obtained from k1 and k2, respectively, so, value between 1 and 2 can be used to approach to it. We have chosen =2, n(D)= AD2e-λD are used to fit into observational raindrop spectra, which is more accuracy than Marshal-Palmer formular (=0). Thus, the regression coefficients (R), characteristic diameters (D1, D2, D3), number concentrations (N), rain rates (I ) and radar echo reflectivity (Z) are all more approximate to observational raindrop spectra than those from the two parameters
The Characteristics of Synoptic and Subsynoptic Scale Environmental Field in the Period of Typhoon Unusual Northward Movement
1990, 1(2): 199-204.
A spatial filter is used to separate the typhoon environmental flow into a synoptic and a subsynopticscale components. Two unusual typhoon paths (Cecil (1982) and Abby (1983)) traviling towards are diagnosted. The results show that the anomalous path occurs in the period of synopticscale circulation adjustment from 500 hPa height field. This kind of typhoons has a tendency moving along the propagation direction of subsynoptic scale disturbance center when the typhoon travels unusually northwards. This is an interesting process, which may be responsible for the unusual typhoon path when the synoptic scale circulation is evidently weak. In light of kinetic energy field, typhoon movement is in accordance with the extending direction of the positive area of GKE (the generation of subsynoptic scale kinetic energy) during this period
Quality of the Weather Forecasting and the Predictive Evaluation in the United States
1990, 1(2): 205-213.
The quality and effect of the weather forecasting and the predictive evaluation in the United States are introduced in this paper. It is shown that the present forecasting level is higher than that 15—20 years ago according to the test for the qualities of the day-to-day weather forecasts (1967—1985) in the U. S. National Weather Service. Especially. It is worth to notice that the level of the objective weather forecasts has been raised significantly, it is worth to notice that the level of the objective weather forecasts has been raised significantly. It is a complex problem with the predictive evaluations. The gain-loss value in response to ‘Yes’ or ‘No’ for weather forecasts and its economic evaluation to the U. S. are summarized and discussed
Cold Surges over the Nansha Sea Area During the Spring of 1988
1990, 1(2): 214-216.
In the paper, the ship observation data over the Nansha Island sea area during February—April 1988 are analysed. It is shown that there are 16 cold surge processes over the area. Also, the influence of cold surges on the weather over the sea surface are presented.
A Statistical Forecasting Model for the High Temperature Disastrous Weather
1990, 1(2): 217-221.
In this paper, using empirical orthogonal function (EOF) expansion method, the temporal and spatial distribution features of high temperature weather causing disaster during the winter wheat milk-filling and milking maturity phases in North China and Weihe River reaches are analysed. Based on this analysis, the optimal regression model for high temperature weather forecasting have been developed by using the principal component reverse selecting method combined with multiple correlation coefficient criteria.
The Outgoing Longwave Radiation Seasonal Variation over the Global Various Areas
1990, 1(2): 222-224.
The Outgoing Longwave Radiation (OLR) monthly mean data within 60oN—60oS (grid length 5o×5o) during June 1974 to August 1983 are used in the paper. It is focused on the OLR seasonal variation over the global various area.