Vol.10, NO.2, 1999

Display Method:
Diagnostic Analysis on the Severe Drought/flood for the Beginning of Flood Season in Southern Part of the South of Yangtze River Valley and Northern South China
Gao Bo Chen Qianjin
1999, 10(2): 219-226.
Based on the precipitation data of 18 stations for the first summer rainfall (April–June) from 1951 to 1995 in northern South China and southern part of the south of Yangtze River valley, the Z-index is calculated, and the severe drought years including 1958, 1963, 1967, 1985 and 1991, as well as the severe flood years including 1954, 1962, 1968, 1973 and 1975 are defined in this region. The characteristics for the frequency distribution and spatial distribution of severe drought/flood are analysed, and the anomalies of SSTA and OLR for the most area of Indian Ocean and Pacific equatorial area are given. The results show that there are obvious differences for the SSTA and OLR anomalies in severe drought/flood years.
Real-time Forecast Experiments Using MM5 in National Meteorological Center
Cui Bo Wang Jianjie Guo Xiaorong
1999, 10(2): 129-140.
A mesoscale experimental forecast system has been established in the CRAY-C92 computer in National Meteorological Center (NMC) based on PSU/NCAR’s mesoscale model MM5 (version 2), to which the local real-time data resources are linked. In order to investigate the feasibility and the accuracy of the mesoscale system for real-time prediction service under the current conditions of computer resources and of the available real-time data in NMC, the real-time forecast experiments are conducted for one and half months during the flood season of northern China in 1996 and in the special weather service period of “Hongkong returning to China” in 1997 using the system with 30 km horizontal resolution. The real-time forecast and verification results show that the forecasts of the precipitation amounts and the heavy rain locations are improved by MM5 more obviously than those by operational model (HLAFS): The mesoscale system could be used as a supplement tool for the weather forecast of city and precipitation model forecasts in higher frequency (less than 6 hours) could not be successful under the current data and computer resources.
Renewed Study on the Warming Process of Shanghai During the Past 100 Years
Jiang Zhihong Ding Yuguo
1999, 10(2): 151-159.
The detailed investigation is carried out in terms of mean monthly, maximum and minimum temperature series of Shanghai from 1880 to 1992. The results indicate that minimum and mean temperatures have obvious increasing trend, especially for the former. From these results, it is known that minimum temperature would be more sensitive to monitor the intensity of greenhouse effect; and maximum temperature exhibited remarkable inflexion trend in the middle and late of 1940s. There were three abrupt warmings, i.e. 1910s, 1930s and the early of 1980s, of the which the first two occurred in daytime, only the last mainly in nighttime. These facts would contribute to renewed study on the warming process of shanghai, China or the globe.
Comparative Study on Two Kinds of Disaster Cloud Clusters over North China
Jiang Jixi
1999, 10(2): 199-206.
The cloud clusters of severe disaster thunderstorm and torrential rain occurring over North China during the summer in 1998 are studied using satellite cloud pictures, conventional data and NWP analysis products. The results show that there are obvious differences for the two kinds of cloud clusters in the environmental conditions of their formation, development and moving model; Satellite cloud pictures combined with other data should be the effective way to monitor and predict the two kinds of cloud clusters.
Synoptical and Climatological Analysis of Snowfall from 1980 to 1994 in Beijing Area
Yi Qingju Liu Yanying Xu Chenhai
1999, 10(2): 249-254.
Based on the data of snowfall from 1980 to 1994, the climatic characteristics of snowfall in Beijing area are investigated. The results show that the interannual variability of snowfall is quite, and the amount of snowfall in November, February and March are larger. Furthermore, There are two kinds of circulation patterns; trough (vortex) pattern, and trough of mid-Siberia and ridge-back of east Siberia pattern. Sufficient moisture and energy are the necessary conditions for snowfall in Beijing area.
Further Discussions on the Design of a Global Multilevel Primitive Equation Gridpoint Model with Variable Resolution
Liao Dongxian
1999, 10(2): 141-150.
Based on a modified MM4 and a limited-area variable resolution gridpoint model, a global multilevel primitive equation gridpoint model with variable resolution has been formulated. It can be proved that the model possesses the integral properties such as mass and energy conservation, and correct transformation between kinetic energy and complete potential energy. In order to overcome the difficulties caused by the fact that the time step chosen should be very small due to the confluent meridians in high-latitudes, a settlement of the problem without filtering waves is suggested, with which the integral properties could be preserved.
Observational Study of Black Carbon in Clean Air Area of Western China
Tang Jie, Wen Yupu, Zhou Lingxi, Qi Lindong, Zheng Ming
1999, 10(2): 160-170.
Black carbon which has a strong absorption in the visible and infrared range is an important component of aerosols, therefore it contributes significantly to the regional and global effects on aerosols. The observational results of black carbon from July 1994 to December 1995 at Mt. Waliguan Observatory are given. The characteristics of black carbon concentration variation are discussed combined with the meteorological observational data, and then the results were compared with the observational data of black carbon in eastern China. The mean monthly black carbon concentration at Mt. Waliguan varies in the range of 130—300 ng/m3, much lower than that of the eastern China. The variation of black carbon concentration shows an obvious episode pollution transportation under the influence of industrial and dense populated areas, and it varies obviously with the ground wind direction. The background concentrations of black carbon at Mt. Waliguan derived from the mode values of the most frequency statistics, are in the range of 50—120 ng/m3. Both the average concentrations and background concentration are lower in winter and higher in spring.
Relationship Between Tropical Circulation Intensity and Summer Precipitation Anomaly in China
He Min
1999, 10(2): 171-180.
The differences between mean monthly zonal wind anomalies at 850 hPa and 200hPa are defined as the South China Sea Tropical Monsoon Index (STMI), the Walker Circulation Index (WKCI) and the Tropical Circulation Intensity Index (TCIX), and the significance of these indexes for synoptic climatology is discussed. TCIX, which is the difference between STMI and WKCI, has a close relation with the summer precipitation in China, especially in the Yangtze River basin. Based on the correlation analysis between TCIX and 500 hPa height fields, SLP, SST and OLR for winter, spring and summer, the possible influence of TCIX on the summer precipitation in China is revealed. The interseasonal variation of TCIX and the correlation with the ambient field of earlier stage are usefull for the forecast of summer rain belts.
Comparison Between Observational Data and Grid Data of Precipitation for the Last One hundred Years in China
Jia Pengqun
1999, 10(2): 181-189.
The global grid data of land precipitation are compared with observational data in China. It is shown that the grid data are good to describe the large-scale features of rainfall field. More than 40 grid datasets which have higher spatial and temporal coverage can represent the data about 200 stations. When using grid data to analyse the precipitation in China, it is necessary to modify the grid series near the border and coastal area in China in order to have a better representativeness for data.
Analysis of the Microphysical Precipitation Mechanism for a Cold Vortex Process
Chen Wenxuan Wang Jun Liu Wen
1999, 10(2): 190-198.
The distribution characteristics of microphysical elements, growing mechanism of precipitation particle and evaporation effects of subcloud raindrop in a cold vortex process are analysed. The results show that the cloud system consists of two vertical lavers, lower warm stratocumulus and principal cool altostratus. The altostratus base is 2 km high, and cloud top is higher than 5 km. The supercooled water exists abundantly in the cloud, the maximum is up to 0.21 g · m – 3 at – 11.20℃, but its distribution is not homogeneous, 87% of continuous distribution width are less than 2.4 km, which is disadvantage to the rime increasing of ice crystal in the cloud. Meanwhile, the evaporation effect of subcloud raindrop is very big, the diameter of raindrops which could not arrive the ground is less than 1 mm. Therefore, the cold vortex process produces the weak precipitation.
Observation and Instrument of Visibility
1999, 10(2): 207-212.
The operational principles of several popular visibility sensors are described and their advantages and disadvantages are compared. Furthermore, the disparity in obserration and instrument of visibility between China and other countries is set forth, and the suggestions that our country should pay attention to the research of visibility sensor are proposed.
Analysis of Circulation Field During the Abnormal Frequency of the Tropical Cyclone Affecting East China in the Flood Season
Wu Daming Lei Xiaotu
1999, 10(2): 213-218.
Before forecasting the frequency of the tropical cyclones affecting East China in the flood season by using statistical interpretation forecasting method, a series of earlier stage researches are made. It’s found that: (1) Abnormal frequency variation of the tropical cyclone affecting East China is caused by the adjustment of mean monthly circulation of the Northern Hemisphere in flood season; (2) The long wave reflecting the characteristics of mean monthly circulation has a good relation to the abnormal frequency variation, especially in abnormal years the weather system and the correlation area are stable; (3) Using the correlation analysis the statistical forecast equation for the frequency variation of the tropical cyclone is set up. Based on the correct short-range numerical forecast for climatic situation the accuracy is about 70% using statistical interpretation forecast method, and if the abnormal variation of mean monthly circulation could be predicted, the trend of abnormal frequency variation could be predicted.
Application of Atmospheric Diffusion Factor in the Bay of East Liaoning
Yang Hongbin, Liu Wanjun, Ma Yanjun, Zhao Guozhen
1999, 10(2): 227-231.
The characteristics of atmospheric diffusion factor in the Bay of East Liaoning are studied using the data obtained from meteorological tower-based sensors at the site located about 800 m from the coast. The results show that the nuclear power station emits pollutants as a high source during its operation. Furthermore, it is found that the lifting level of plume is lower than 30 m when wind speed is greater.
The Monitoring Method and Model of Deep Soil Layer Moistures by Remotely Sensed Data
Chen Huailiang, Feng Dingyuan, Zou Chunhui, Guan Wenya
1999, 10(2): 231-237.
By using NOAA/AVHRR remotely sensed data, the monitoring method and model of deep soil layer moisture with GIS technology based on thermal inertia are developed. The results show that the effects of the deep soil layer moistures calculated from soil surface moistures obtained by remote sensing are better than those in establishing a statistical model directly by distinguishing soil layers, a good nonlinear relation exists between the soil surface layer moisture and deep soil layer moisture.
The Impacts of Low Temperature on Corn Seedling Physiological Response
Gao Suhua, Guo Jianping, Zhang Guomin, Wang Lianmin, Wang Lizhi
1999, 10(2): 238-242.
Putting the 3rd—leaf stage seedling of late variety of corn, Jidan 159 in the low temperature of 6℃ and 10℃ to treat for 3 and 6 days, it is shown that the proline content is increased obviously, and the electric conductance is also raised. The content of solubility protein is increased firstly and then decreased with the prolongment of treatment time. The SPAD value of chlorophyll is decreased, and the photosynthetic rate is decreased.
Monitoring Rice growth Trends Using NIAA /AVHRR Data
Shi Yuhong, Piao Ying, Zhang Jing, Li Guochun
1999, 10(2): 243-248.
NOAA/AVHRR data (1992—1996) combined with the observations of agronomic parameters of crop growth were used to analyse the patterns of normalized vegetation index (NDVI) for rice from transplanting to harvest in order to monitor the rice growth trends dynamically in Shenyang.