Vol.6, NO.2, 1995

Display Method:
Tracking Features of the C-band Wind-finding Primary Radar and Its Prospect of Utilization
Huang Bingxun
1995, 6(2): 153-162.
Utilizing a vast amount of raw data obtained from the field test and flighting experiments in Chengdu and Zhengzhou for the first C-band wind-finding prototype radar in China, the static features of tracking a fixed target and the dynamic features of tracking a moving target have been analysed in detail. The results indicate that in the case of a fixed target to be tracked, this radar has a very high tracking accuracy. In the case of a moving target to be tracked, the discrepancy of the tracking data will increase still further. Fortunately, the rate of data collection of the radar is very high. Using suitable smoothed method and selecting suitable temperal interval for the calculation of wind aloft, the wind profile with high accuracy (e. g. 1 m/s) and moderate fineness of its stratification can be obtained
The Difference of the Heating Vertical Profile Between Cumulus Precipitation and Stratus-cumulus Mixing Precipitation
Zhu Tong, Wang Xiuqing, Zhu Rong
1995, 6(2): 171-176.
Two cases of heavy rainfall occurred in Jilin Province in July, 1991 are diagnosed and simulated by using MM2 and MM4 mesoscale models. The results of diagnostic analyses show that the case of 20th July is a mesoscale cumulus complex (MCC) developed in warm area. The vertical profile of the apparent heat source (Q1) for this heavy rain from the only cumulus cloud has two peaks. However, for case 21th to 22th July, MCCs embody in stable precipitation of cyclone with only one peak of Q1 apparent heat source vertical profile. This single peak is over about 550 hPa and is lower than the upper peak of the former case. The results from numerical simulation indicate that the heights of cumulus heating peaks for different weather systems are different and, this different of heating peak heights may cause different feedback to large scale environmental field.
The Phase Propagations and Geographical Features of the 10~20 Day Oscillation in Summer 1982/1983
Peng Ru, Wu Bingyi
1995, 6(2): 206-212.
By using CEOF, the phase propagations and geographical features of the 10~20 day low-frequency oscillations have been discussed using the data of daily 850 hPa and 360 hPa ECMWF zonal wind data from June to August, 1982/1983. The results show that (1) On 300hPa, the oscillations have a obvious region, it was to the south of 20°N from India to the east of the Philippines in 1982. On 850 hPa, the obvious regions of oscillation were in 5o~15°N, 75 o ~132.5E, and the southeast coast of China in 1982. However, only the obvious regions of oscillation were in the southeast coast areas of China, in the southeast of the Bay of Bengal, and to the north of Malaysia in 1983. (2) On 300 hPa, a source of the oscillation was in 30°~40°N, 85°~90°E in 1982, and the branch oscillation can propagate south ward to the north of the Bay of Bengal around 28°N. However, oscillations converged in 35°~40°N, 80°~90°E in 1983
A Triple Nested Mesoscale Model and the Numerical Simulation for Heavy Rain
Zheng Guoan, Cuo Xiaorong
1995, 6(2): 129-137.
A triple nested High resolution Limited Area Model (HLAM) is recently developed and runs on computer CYBER-992. The model’s domain, geographical location, lateral boundary width, especially horizontal resolution are highly flexible. A case of heavy rain is simulated using this model with horizontal resolution of 50 km. The results are encouraging: (1) The location of low pressure centers, the area of heavy rainfall and the trend of rain-band are more closer to those of analysis as compared with low resolution nested grid model. (2) Although the area of high resolution model’s simulation is reduced, the forecast effect is not influenced and 48 hour forecast still has high precision. Preliminary experiments show that HLAM can be developed into a regional high resolution model for mesoscale research and operational forecasts.
A Study of the Characteristic of Water Vapour Image for Severe Weather in North China
Zheng Xinjiang, Zhang Fengying, Lu jie, Huang Tao, Ding Haifang, Wang Feng
1995, 6(2): 138-145.
Based on NOAA TOVS infrared water vapour brightness temperature data for 37 times from 1991 to 1993, the four types of summer severe convective weather process and precipitation have been summarized by analyzing summer severe weather process over north China. It provides new basis for analyzing and forecasting such kind of weather.
Structure Evolution of Typhoon No. 9216 After Landing
Tao Zuyu, Wang Hongqing, Huang Wei, Tian Baijun
1995, 6(2): 146-152.
The GMS satellite data and diagnostic field are used to analyze the structure and evolution of the cloud system of landed Typhoon No. 9216. The analysis indicates that the structure and evolution of GMS satellite images reflect the close relationship between Typhoon No. 9216 and the upper and low level environmental currents. The exceptional strong storm tide and the extensive heavy rainfall region from Typhoon No. 9216 are caused by the effects of the strong divergent current on the right side of upper level jet entrance and the very strong low level jet with warm advection
The Numerical Experiments of Southwesterly Formation over the Nansha Sea Area with the Effects of Terrain and Heat Perturbation
Zhang Xiang, Zhou Xuequn
1995, 6(2): 163-170.
By using a five layer limited area primitive equations model, the terrain, heating perturbation over South Asia and a cooling perturbation over Australia are incorporated, respectively in the numerical model to discuss their effects on the southwesterly formation over the Nansha Sea area. The experiments of terrain show that the topographic effect is necessary on the southwesterly formation, but the topographic effect is not strong enough to make the southwest wind velocity reach 12 m/s. Furthermore, with the help of the effect of terrain, the experiment results including heating perturbation over the Philippines and the cooling perturbation over Australia, respectively, show that they can both make the southwesterly formation of above 12 m/s over the Nansha sea area. However, the heating perturbation over the Bay of Bengal has no effect on the formation of southwesterly over the Nansha Sea area
A Study of Formation for “Black Storm” Using GMS-4 Imagery
Jiang Jixi
1995, 6(2): 177-184.
The casue of formation for the black storm over the part regions of Gansu and Ningxia Provinces during late afternoon and early night on 5 May 1993 are investigated using GMS-4 S-VISSR data every hour and conventional data. The results show that it was mainly caused by mesoscale convective system with a squall line in advance of a cold front. It moved eastward and basically consorted with 700~500 hPa mean flow. The predictability of this “black storm” is discussed.
Fractal Based Image Coding Scheme
Gu Qijun, Yang Hailang, Xu Yumao
1995, 6(2): 185-191.
An image compression technique that incorporates Peano scan with a fractal-based coding scheme is described. The proposed approach is very simple and clear, and its implementation is easy, 1/10 compression rate is achieved. The reconstructed image retains original picture quality and has well psycho-visual effects. This scheme not only can be used in aerial photograph and remote sensing image processing, but also has wide application prospects in earth science, biology, medicine, military affairs and communication
The Parameter Study of a High-order Turbulence Model
Bian Huisheng, Yan Pen, Zhu Cuijuan, Li Xingsheng
1995, 6(2): 192-198.
A group of parameters which are proposed by using field observational data in the surface layer combined with second-order closure turbulence equations has been developed for a high-order turbulence model. Applying the parameters of this paper’s and Mellor’s which obtained from lab experiments to second-order closure equations respectively, the two groups of relative curves of ΦM(), ΦH () with have been maped out. The graphs show that the two groups of curves are almost overlapped and also fit the results of Businger’s field observational data very well. In the other two groups of relative curves of (w*)1/2 (), (θ*2) 1/2() with , the curves of this paper have far less deviation than that Mellor’s compared with the data of UTAH, but have a little greater error than that of Mellor’s compared with the data of KANSAS.
The T63 Four-dimensional Data Assimilation Experiments in National Meteorological Center (NMC)
Tu Weiming, Xie Shaocheng, Chen Weihong
1995, 6(2): 199-205.
This paper describes an experimental scheme of the four-dimensional data assimilation system in NMC and its experimental results. The results indicate that this assimilation scheme is stable on computation. Using the initial condition provided by the scheme, the 7-day global forecasts were produced by T63L16 medium-range numerical weather prediction spectral model. Comparison of T63L16 prediction system with T42L9 operational one shows that T63 is better than T42.
Application of Tschebyscheff Functions to the Vertical Discretization of Atmospheric Models
Liao Dongxian
1995, 6(2): 213-219.
Discussions are made on the vertical discretization of current global spectral atmospheric model. Based upon Tschebyscheff functions methods are given for integrating the hydrostatic equation and the continuity equation and for computing vertical advection and vertical diffusion. Furthermore, in the case that the vertical derivative of a meteorological element is discontinuous, the measures to be taken are discussed and suggested
Solitary Rossby Waves with the Beta Parameter and Dipole Blocking
Luo Dehai
1995, 6(2): 220-227.
Using a generalized beta-plane approximation f =fo+βoy -(δ0 /2)y2 , a kind of the solitary Rossby waves excited by theδ0 term excluding effects of shearing basic flow and topography et al is mainly investigated. The computational results show that the obtained solitary Rossby wave with meridional wavenumber 1 has a dipole structure with a high pressure in the north and a low in the south, which mainly exists in the weak westerly wind. On the other hand, the energy of dipole easily accumulates with the latitude. Thus, the beta parameter with the change of latitude may be one reason of producing dipole blocking in the mid-high latitudes.
A Review of the Study on Simulation of Regional Climate
Liu Yongqian, Ding Yihui
1995, 6(2): 228-239.
Regional climate modeling is one of the methods developed in recent years to study the climate and climate change on regional basis. Owing to better description of terrain features and underlying surface condition, and incorporating of detailed land-surface process, the regional climate model can be used to capture regional-scale temperature and precipitation distributions as well as features of soil moisture variation, which are difficult to be resolved by GCMs. In addition, the regional climate simulation is important for understanding regional response of global warming and effect of ecology and environment caused by greenhouse gasses forcing. The present paper makes an attempt to summarize the state of the art of regional climate model and numerical simulation results, and addresses the problems to be further studied.
A Study of the Distribution and Evolution Characteristics of Stratospheric Ozone over China Using SAGE II Data
Chen Hongbin, Wang Pucai
1995, 6(2): 240-245.
On the basis of SAGE Ⅱ observation data from October 1984 to March 1992, the retrieval of the stratospheric ozone (O3) is perfomed. The distribution and evolution characteristics of the stratospheric O3 varying with seasons and the vertical profiles for four months (January, April, July and October) are given
Numerical Simulation of Air Motion Associated with Forest Fire
Zhou Guangyuan, Liu Gongbo, Hu Zhijin
1995, 6(2): 246-251.
A Study of the interaction between the behaviour of forest fire and associated air motion is very important for extinguishing the fire. A two-dimensional non-linear quasielastic model of air motion associated with severe temperature disturbance was developed. The structure and evolution of air motion and temperature fields associated with forest fire under three kinds of conditions were simulated, which are calm atmosphere, vertically sheared wind and spreading fire with surface wind. The results were reasonable. Differences of air motion and heat transfer under these conditions were investigated and the surface reverse wind was analyzed.
The Principal Component Analysis for Corn Yield in Gansu Province
Han Yongxiang, Ge Bingjiun
1995, 6(2): 252-256.
The tendency corn yield term (Yt) and climatic corn yield term (Yw) of Gansu province are expanded by means of EOF. Their first characteristic vectors show that general tendency is consistent with the tendency yields of Gansu. The centers of large values is the large variabilities. By means of correlation analysis between Yt time coefficients and Yt for station, and the same method to Yw, eight stations for predicting corn yield are chosen, which represent basically yield levels and growing conditions under various kinds of agroclimatic regions of Gansu Province.