Vol.8, NO.1, 1997

Display Method:
Design of a Global Gridpoint Multilevel Primitive Equation Difference Model with Variable Resolution
Liao Dongxian
1997, 8(1): 1-10.
Based upon an even gridpoint difference model, a global gridpoint multilevel primitive equation difference model with variable resolution has been designed. It is shown that in the adiabatic and inviscid case, if the former model satisfies certain conditions, and can be proved to be mass-and energy-conserving, and has consistent conversions between kinetic energy, potential energy and surface potential energy in the continuous case, the latter model also has similar properties. Furthermore, it is quite convenient to transform the former model into the latter one, and the amount of extra work is small.
Two Geometrical Problems in Cloud Motion Wind Algorithm
Xu Jianmin, Zhang Qisong, Wang Dachang, Fan Changyao
1997, 8(1): 11-18.
Mapping correction and wind vector calculation in cloud motion wind algorithm were discussed. If geographical matching between images is not accurate, mapping correction can amend systematic errors caused by satellite movement relative to the earth. Wind vector calculation based on an ellipsoidal earth was also described. The formulas for wind vector calculation are simple and accurate. Cloud motion wind calculation is essentially a geometrical issue. Careful consideration at geometric issue is an important approach to error reduction.
Potential Effects of Climatic Variation on Geographical Distribution of Wheat in China
Dai Xiaosu
1997, 8(1): 19-25.
The potential CO2-induced impacts on the geographical shifts of wheat growth zones in China were analyzed based on GCM outputs. It is shown that the wheat growth regions may move northward and westward under the condition of a doubled CO2 climate. The wheat cultivation features and variety types may also assume significant changes. Climatic warming would have a positive influence in Northeast China, but high temperature stress may be produced in some regions of central and southern China. Higher mean air temperatures during wheat growth, particularly during the reproductive stages, may increase the need for earlier-maturing and more heat-tolerant cultivars.
Research on Determination of Station Indexes and Division of Regional Flood/Drought Grades in China
Ju Xiaosheng, Yang Xianwei, Chen Lijuan, Wang Youmin
1997, 8(1): 26-33.
By use of the monthly precipitation data of eight sampling meteorological stations in China from 1951 to 1995, the three single indexes for flood and drought were tested and compared with each other. The Z-index was recognized to be optimum. On this basis, the 80 stations are selected in North China to discuss the regional indexes and grades which can reflect both the spatial and temporal distribution and intensity for regional floods and drought.
Calculation Method for Initial Value of Kalman Filter and Its Application
Lu Ruhua Xu Chuanyu Zhang Ling Mao Weixing, Zhang Ling, Mao Weixing
1997, 8(1): 34-43.
For the purpose of application in meteorology, the principal theory and calculating method of Kalman filter used in weather forecast operational system are discussed. Then the testing results in different seasons are described. Furthermore, its adaptability, stability and usability for various numerical models are analysed. The method is of great advantage for the weather forecast, and the prospects of application in the area of meteorology are very hopeful.
A Study on Numerical Simulation of Discontinuous Northerly Jump of an Onland Typhoon and Its Torrential Rain
Ding Zhiying, Chen Jiukang, Ma Guang
1997, 8(1): 44-52.
Using MM4 (PSU/NCAR) model, the torrential rain process of typhoon from 2000 BT. August 31 to 2000 BT. Sept. 1, 1992 was simulated and studied. The results show that the typhoon discontinuous northerly jump was related to the westerly trough and the feedback of cumulus convection latent heating, and the development of cumulus convection in the south rain area of inverted trough enhanced the transporting for the water vapor, momentum and heat from south to north. These processes would cause a great increasing of precipitation. The feedback of cumulus convection latent heating affects greatly the upper and lower level jets and the motion of the typhoon.
Observational Analysis of Surface O3、NOX and SO2 in China
1997, 8(1): 53-61.
From August 1994 to August 1995, the continuous in-site measurements of surface O3, NOX and SO2 have been made in three sites of China which are Lin’an, Longfengshan background stations, and Waliguan baseline observatory. The preliminary analysis of the data indicates that the average concentration, monthly and diurnal change of surface O3 mainly depend on geographic environment, sea level and weather conditions. During the priods of measurement, the average concentrations of surface O3 are 34.8×10-9 in Longfengshan, 39.1×10-9 in Lin’an and 49.3×10-9 in Waliguan, respectively. The monthly average concentrations of surface O3 are quite different in these sites, in Lin’an and Longfengshan, O3 concentrations show lower in December and January, and in June and July, respectively, and higher from the end of October to early November, while in Waliguan, the monthly variation of O3 concentration is much smaller, the lowest value in December, and the highest in June. The diurnal variation of surface O3 concentration shows an obvious diurnal cycle with a maximum in the afternoon and a minimum in the early morning in Longfengshan and Lin’an, but with a small diurnal variation in Waliguan. The distributions of NOX and SO2 show an obvious local characteristies, the average concentrations are 2.7×10-9 (NOX) and 0.7×10-9 (SO2), 8.1×10-9 (NOX) and 16.1×10-9 (SO2), 0.04×10-9 (NO2) and 0.15×10-9 (SO2), respectively in Longfengshan, Lin’an and Waliguan stations
Observation and Analysis of SO2 and NO2 in Clean Air of Western China
Yu Xiaolan, Tang Jie, Li Xingsheng, Li Baosheng
1997, 8(1): 62-68.
Atmospheric SO2 and NO2 were sampled during the period from August 1994 to July 1995 by using filter packs (FP) method, and the concentrations of these gases were analysed with ion chromatography (IC) at Waliguan background baseline station (3810 m asl, 100o54’E, 36o17’N) of Qinghai Province, western China. It is found that the average concentrations of SO2 and NO2 are 0.147×10-9 and 0.055×10-9 ,respectively. There is a good correlation between SO2 and NO2 concentrations with a coefficient of 0.87, the ratio of SO2 to NO2 derived from the linear regression is about 2.6. Furthermore, the concentrations of SO2 to NO2 vary with seasons and wind directions. Higher concentrations are from easterly, and lower from westerly. The concentrations of SO2 and NO2 are lower in winter season and higher in summer.
A Study of Drought/Flood Type in Eastern China
1997, 8(1): 69-77.
Spatial pattern of drought/flood was studied based on the drought/flood level time series of 524-year (1470~1993) in 25 stations of eastern China. Due to the differences between EOF and REOF methods, the improvement on the old six drought/flood types was demonstrated by using REOF analysis. It is better to show the factual drought/flood pattern and easier to study temporal characteristics by six key area. Also, the main characteristics of drought/flood in eastern China were described for last five hundred years or so.
A Mathematical Model for Searching Analogue Weather Process
Liu Jingtao, Gao Tao, Kang Ling
1997, 8(1): 78-84.
A new mathematical model is developed for searching the analogue weather process, in which the discriminant matrix is made by means of Saaty method. By using the matrix to discriminate, the analogue order and analogue degree are calculated. This mathematical method has been proved to be very useful in the operational weather forecast for the past 3 years
Climate Noise and Estimating the Dimensions of Climate Attractor
Xin Guojun
1997, 8(1): 85-91.
The dimensions of climate attractor are estimated from phase space trajectories of observed climate variables (Southern and Northern Hemisphere surface air temperature) based on the method estimating the fractal dimensions given by Grassberger and Procaccia. The results show that the fractal dimensions of climate attractor are 3.3~3.7 for the Southern Hemisphere, and 3.2~3.7 for the Northern Hemisphere. They provide the primary information for the descriptions of selt-similar properties of the climate attractor, and the four independent variables are needed at least for simulated climate system. Also, the effects of the noise on estimating dimensions of climate attractor are discussed
A Study on Effect of Topography on the Stability of Gravitational Inertial Mode in Geostrophic Flow
Zhong Zhong
1997, 8(1): 92-98.
By using a two-layer homogeneous fluid linear model with topography, including the influence of nonuniformity of lower fluid mean depth, the propagation and stability of geostrophic flow at low levels were studied.
Semi-lagrangian Scheme and Its Application in Numerical Simulation and Prediction
Dong Min
1997, 8(1): 99-108.
The basic principle and numerical techniques of the semi-Lagrangian scheme are described. The main advantages and some problems are pointed out. The recent applications of this scheme in numerical simulation and prediction and the research activities are reviewed.
Application of Reference Atmosphere to the NMC’S Spectral Model
Yang Xuesheng, Chen Jiabin, Sun Lijuan
1997, 8(1): 109-113.
The reference atmosphere scheme, which is a function of space and time, was presented and introduced into the medium-range forecast model T63L16. The results indicate the forecast quality and the threat-score for precipitation were improved to some extent
The Interaction of Synoptic and Subsynoptic Scale Systems in a Torrential Rain Process
Xue Qiufang, Liu Jinliang, Ding Yihui
1997, 8(1): 114-118.
On the basis of synoptic analysis, the terms of synoptic and subsynoptic scale kinetic energy and the nonlinear kinetic energy interaction terms were calculated, respectively, in order to analyze the main dynamical process of interactions between their kinetic energies of synoptic and subsynoptic scale systems in the precipition process. The results show that the kinetic energy interactions between synoptic and subsynoptic scales exist in the torrential rain system, and the motion of subsynoptic scales increases kinetic energy of synoptic scale, and so as to support the torrential rain system
A New Method of Analysing Climate Jump and Its Application
1997, 8(1): 119-123.
On the basis of approaching the current methods of climate jump, being aimed at the faults of those methods, Fisher optimum separation method is introduced and combined with the statistic test of those, thus a new method is produced. By using this method, the climate jumps about drought/flood series for Xi’an, Baoji and Hanzhong areas are studied, respectively. The results show that there exist local and non-local climate jumps in eastern Northwest China
The Contrast and Analysis of Echo Depths Between Two Types of Weather Radar
Hu Mingbao, Fan Guangsheng, Qi Yong
1997, 8(1): 124-128.
By means of the contrast and analysis between the data of 712 and 716 radars, it is shown that there are great differences of the echo depth and echo intensity between the two radars, and the method in operation for 716 radar is put forward