Vol.4, NO.3, 1993

Display Method:
Climate Oscillation of the Summer Rainfall Anomaly Pattern for the Flood Season of 1991
Zhang Xiangong Wei Fengying
1993, 4(3): 310-319.
The distribution of summer rainfall anomalies in 1991 consists with the EOF expanded third eigenvector from the 《Yearly charts of dryness/wetness in China for the last 500-year period》. By analyzing the time coefficient of the third eigenvector it is found that the dryness/wetness pattern index in 1991 appears a Bruckner cycle with 37 years and is related to the SOI with the cycle of 36.7 years. It is also found that it has relation to the globe temperature change (the correlation coefficient between them is 0.41) and to the correlation distribution of SST in North Pacific, which is similar to the sea surface temperature anomalies pattern during the E1 Nino period. Therefore, the appearance of drought/flood pattern in 1991 may be related to the inherent climatic oscillation, such as the long-term variation for itself in the dryness/wetness pattern, the globe climate warming, and particularly, the intensification phase of the ENSO events.
Diagnosis and Numerical Simulation for the Genesis and Development of Mesoscale Systems with Heavy Rainfall Part II: Numerical Simulation
Cheng Linsheng Ying-Hwa Kuo Peng Xindong
1993, 4(3): 269-277.
Using a improved model of MM4, the genesis and development of the mesoscale systems with the heavy rainfall are further discussed based on the three typical heavy rainfall events (81.7, 81.8 and 91.7) in China. The principal findings are: It is important to the mesoscale systems that a cyclonic vorticity is generated and developed within an unstable and warm air with moist, while a persistently intensive ascending motion is maintained with whole vorticity column. The effect of the condensation latent release on the mesoscale systems development is significant. The various physical processes, model parameterization, the configulation of the Qinghai-Xizang Plateau forming the external forcing influence and the model spatial resolution and so on are all important to the simulative results concerning the structure, evolution and precipitation for the mesoscale systems producing heavy rainfall.
An Analysis of the Meso-convective Cloud Clusters in Mei–yu Front
Li Yulan Tao Shiyan Du Changxuan
1993, 4(3): 278-285.
By using the hourly GMS infrared imagery and conventional meteorological data, an analysis of the meso-convective cloud clusters in the Mei–yu front during the rainstorm period in the reaches of Yangtze and Huaihe Rivers in 1991 is made. It includes the basic characteristics of the meso-convective cloud clusters in the Mei–yu front (such as, source, life cycle, direction and velocity of their movements, and their types of genesis etc.). The importance of the environmental conditions, especially the interaction between the cloud systems of middle and low latitudes for the formation of the meso-convective cloud clusters is discussed. Finally, a cloud model and a conceptual model for the development of meso-convective cloud clusters in the Mei–yu front is given
The Mesoscale Analysis of the Mei–yu Front Cloud System in 1991
Xiang Xukang Ma Lan Wang Dachang
1993, 4(3): 286-292.
According to the analysis of the GMS digital stretched cloud image and conventional precipitation data, it shows that storm and heavy rainfall in the Changjiang-Huaihe River valley during Mei–yu period of 1991 is mainly produced by mesoscale cloud clusters. They are: vortex-warm front shear cloud clusters and cold front shear cloud clusters. Most of them are meso-β scale cloud clustets. The mean life time is 5—6 hours and the mean minium cloud top temperature is –69℃. It is seen that the vortex-warm front shear cloud clusters are created on the eastern side of the vortex center and in the left front of low level jet axis, while the cold front cloud clusters are located in the confluence site of the rear of Mei–yu front cloud system with the southwest monsoon. In addition, the relationship between cloud cluster top temperature and precipitation are estimated. It is found that the top temperature of 75% of cloud cluster with rainfall of 5mm/h and over is –64℃ or down.
The Characteristics of the Cloud System for Jiang-Huai Severe Rainfall in June of 1991
Ye Huiming Zhang Fengying Ran Maonong Zhu Xiaoxiang Li Guizhi
1993, 4(3): 293-300.
The mean cloudiness distribution of the severe rainfall over the Jiang-Huai area in summer of 1991 is described by processing the infrared data of GMS-4 geostationary satellite. In basis of the GMS-4 hourly image animations and 3-hour interval images for the six severe rainfall events in June of 1991, the evolutionary images of the three kinds of cloud types for the interaction of middle-low latitude cloud system during the Mei–yu period are presented. Also, the features of water-vapour transportation are studied based on the TOVS water-vapour retrievals processed and θse field in the lower troposphere for the severe rainfall.
The Characteristics of “OLR” for 1991 Mei–yu
Jiang Shangcheng Yang Xifeng Wei Ge Yang Wenbin
1993, 4(3): 301-309.
Using the mean pentad Outgoing Longwave Radiation (OLR) data observed from the NOAA satellites and the conventional weather observations for the 1991 Mei–yu season, the diagnostic study of the characteristics of the OLR is conducted. The paper describes the OLR and its anomalies pattern and the characteristics of propagation of the intraseasonal variation (ISV) of OLR during the 1991 flood Mei–yu periods. It is revealed that the variation of the ITCZ and the subtropical high are related to the evolution of the Mei–yu. The relationship between the anomalies of OLR over Tibet Plateau and the flood Mei–yu is also revealed. The results show that the earlier ITCZ occurrence in the western Pacific and the positive OLR anomalies (snow cover less than normal) over Tibet Plateau in winter are the important indications for the earlier onset date of the 1991 Mei–yu. Finally, by analyzing the features of the OLR pattern for the active and break phases of the 1991 Mei–yu and comparing with that of Indian monsoon, it is found that their onset dates are different from each other and their active phases either same or contrary. It is suggexted that the complication of the Mei–yu in China is mainly due to the interaction between the middle latitude cold air and two kinds (east Asia and south Asia) of monsoon events.
The Relationship Between Low Frequency Oscillation over Asia Monsoon Region and Continuous Heavy Rain in the Lower Reaches of Yangtze River Valley
Yang Qiuming
1993, 4(3): 320-326.
By using the principal component analysis and the power spectral analysis with nonintegral waves, the characteristics of the spatial distribution and low frequency oscillation for 500 hPa circulation over Asia monsoon region during the early summer in 1991 are investigated. The results show that the first five major spatial patterns from the principal component analysis respond to the influence of different monsoon systems, respectively, and time coefficients have the remarkable periods of 12―22, 28―31, 43―65 days. The variation of oscillations is related to the heavy rain in the lower reaches of Yangtze River valley. It is important to the occurrence of continuous heavy rain that interactions between the low frequency waves which are forced by the diabatic heating anomalies and the continent-ocean heat contrast at the low latitude in Asia will lead to the anomalies of energy dispersions toward extratropical atmosphere
Some Features of Walker and Hadley Circulations During the Period of Torrential Rain in 1991
Zhang Guangzhi
1993, 4(3): 327-332.
In this paper, a study on Walker and Hadley circulations over the Yangtze and Huaihe River Valleys in 1991 has been made. The areas for Walker and Hadley circulation analyses are in the Equatorial Pacific and along 115°E, respectively. It is found that the torrential rain and flood in 1991 correspondings to the situations of the weakening easterlies and the strengthening westerlies. An anti-Hadley circulation (i. e. the eastern-Asia monsoon circulation) can also be seen and strengthened over the eastern China. Analyses of divergence wind field indicate that a cross-equatorial current of divergence wind is found in the lower troposphere and out-flow current in the upper troposphere during the torrential rain period
Verification of Quantitative Forecasts for Storm Rainfall During the Period of Changjiang-Huaihe Mei–yu in 1991
Dong Liqing
1993, 4(3): 333-340.
Threat Score is employed to verify the quantitative forecasts for the storm rainfall in the Changjiang-Huaihe region in the periods of June 12―15 and June 29―July 12,1991. The results suggest that the subjective forecast for the heavy rain and torrential rain is better than the objective ones; numerical prediction has achieved significant improvement in some aspects of forecasting precipitation
Experiments of Initial Values Effect on Numerical Weather Forecast for Heavy Rain
Zhu Zongshen Zheng Guoan
1993, 4(3): 341-348.
In basis of statistical interpolation, the objective analysis initial values from different data sources and horizontal resolutions have been obtained by using the two heavy rain processes during 7―9 November of 1990 and 27―29 July 1991. The influence of these initial values on the 48-hour heavy rain forecast in the eastern China has been discussed by using the numerical simulation of triple nested grid model
An Analysis of Three Cases of Heavy Rains in Jing-Jin-Ji Area of China in 1990
Liu Yanying Xu Chenhai Wu Baojun
1993, 4(3): 349-355.
In this article, three cases of heavy rains which occurred in the Jing-Jin-Ji area of China have been analysed. The results show: 1. These heavy rains are affected by the upper trough with cold front. 2. Ten hours before the rains there exist high energy tongues of moist available energy in the southwest of the rain area and the convergence of energy and vapor in the north and west of the high tongues. 3. The frontgenesis of the lower troposphere and the lifting role of the mountain are the direct triggering mechanisms.
Numerical Study of Influence of the Qinghai-Xizang Plateau on the Late Spring Cold Spell Event South of the Changjiang River
Zheng Qinglin Song Qingli Jiang Ping
1993, 4(3): 356-361.
By employing the improved T42L5 spectral model and utilizing the ECMWF data of 12 UTC 25 March 1985 as the initial field, a numerical study of the effect of the Qinghai-Xizang Plateau on the formation of the cold spell in the late spring south of the Changjiang River has been made. The results show that the dynamic effect of the Plateau can help the cold air move along the east of the Plateau from the north to south and the south trough with generation and maintenance on the southeast side of the Plateau. Due to the dynamic effect of the lee wave east of the Plateau, sough trough becomes deeper and moves towards the east, with the result that the low temperature process can remain in the south of the lower reaches of the Changjiang River.
The Technique for Determining Tropical Cyclone Intensity with Enhanced Satellite Cloud Imagery
Li Xiufang Fan Huijun Yan Fangjie Hu Zhibo
1993, 4(3): 362-369.
This paper develops a new technique for determining the tropical cyclone intensity, which is based on the statistical relationships of cloud intensity index in EIR imagery with the maximum velocity and the minimum sea level pressure of tropical cyclones in the period of 1983―1988. A flow diagram of this technique in a man-computer interface structure is designed for operational use in NMC of China. This technique is more objective and quantitative than those used in the NMC
Chemical Composition and Origin of a Duststorm over Beijing
Wen Yupu Yang Dongzhen
1993, 4(3): 370-378.
In this paper, the origin of aerosol particle for a severe duststorm process, which occurred in the period of 25—26 April 1990 over Beijing, is discussed based on the analyses of the weather situation concerning the duststorm and data of the chemical elements, as well as the rare-earth element distribution of the aerosol particles collected in Beijing. The results show that the aerosol particles of the duststorm was made of the sand soil originated from the areas where the strong wind was appeared
A Preliminary Investigation of the Floods in 1823 and Their Socioeconomic Impacts in China
Zhang Jiacheng
1993, 4(3): 379-384.
The article gives a tentative description of the serious floods and their socioeconomic impacts in North China and Lower reach Yangtze River basin during the third year of Emperor Dao–guang’s reign (1823) in Qing Dynasty. Also, the article makes effort to analyse this example in causes and mechanism of the disaster formation process, which would be of interest in formulating the disaster mitigation strategies for China