Vol.10, NO.4, 1999

Display Method:
The Climatic from Troposphere to Lower Stratosphere at Mid-latitude Along 120° E and Its Relation with Ozone Variation
Ge Ling Zhao Yuandong
1999, 10(4): 445-452.
Using the mean monthly temperature data of Nanjing, Shenyang and Hailar from surface to 30 hPa during 1958 to 1995, the variable features on the climatic variability of the regions along 120° E from 30° N to 50° N with altitude-latitude-season are studied, and the relations with ozone variation in East Asia, adjacent area of same latitude and Eurasia key areas of high-latitude are also discussed.
Forecast Experiment for Operational Application of Water Loading Prediction Model
Yan Zhihui Guo Xiaorong Zhao Junying
1999, 10(4): 453-461.
This paper is based on the operational limited area prediction model run in National Meteorological Center. The horizontal resolution was increased from 1°×1° to 0.5°×0.5° grid in latitude and longitude. The vertical layer was increased from 15 to 20, and the explicit precipitation scheme was introduced into the model physical processes. Using the improved model, a case of forecast experiment on heavy rainfall caused by a landing typhoon in August, 1997 was made, and the results are reasonable.
Regionalized Weighted Method of Consensus Forecast for Rainfall During Flood Season
Zhou Jiabin, Zhang Haifu, Yang Guiying, Peng Yao
1999, 10(4): 428-435.
A regionalized weighted method of consensus forecast is proposed which is not confined by the number of sample. The assemble forecast is got based on the score data of different forecast in Previous Periods. 16 kinds of schemes are designed. The results indicate that the method possesses certain accuracy and is able to be used in operational forecast.
Regional Consensus Forecast Method with Dynamic Weighting for Summer Precipitation over China
Wei Fengying
1999, 10(4): 402-409.
The regional consensus forcast with dynamic weighting for summer precipitation over China is described. Dynamic and normalized weighting coefficients are to forecasting model for each region of China in accordance with the predictive skill of several individual models for past records. Here, dynamic weighting means that the closer the record is from forecasting origin time, the greater the weighting coefficient is. And the forecast of the precipitation over China is composed of the consensus forecast of 10 regions. The experiments for the independent sample of 1990—1998 show that the predictive skill of the consensus forecast is better and steadier than that of individual forecasting.
The Influence of Soil Temperature Abnormality over the Tibetan Plateau in Spring on Summer Flooding of the Mid and Lower Reaches of the Changjiang River in 1998
Bai Jingyu Xu Xiangde
1999, 10(4): 478-485.
The relationship was investigated between the torrential rain in the mid and lower reaches of the Changjiang River in summer 1998 and the thermal abnormality of the Tibetan Plateau in spring 1998. The statistics show that the 3-D thermal structure of 1998 with positive abnormality in the southern part and negative abnormality in the northern part is Just like that of 1991 and 1993 which are flood years. Meanwhile, the sensitivity experiment also verified that the 3-D thermal. Abnormality of the Tibetan Plateau in spring was the one of key consequences of the subsequent summer precipitation abnormality in 1998
The Experiment of Extraseasonal Prediction During the Rainy Season in China by OSU/NCC GCM
Gao Xuejie Zhao Zongci
1999, 10(4): 462-469.
By using the ensemble prediction method, the experiment for extraseasonal prediction of precipitation during the rainy season in China from 1982 to 1995 was made by GCM/mixed-layer ocean and sea ice model (OSU/NCC). The results show that the model has certain ability in the prediction of precipitation during the rainy season in China. It is indicated that the prediction is especially acceptable in some areas.
Predicting Regional Climate with Self-memorial Model and Its Results
Feng Guolin, Cao Hongxiong, Wei Fengying
1999, 10(4): 470-477.
A self-memorial model for regional climate prediction is derived on the basis of the self-memorization principle of atmosphere. It is composed of difference-integration equations with variables of surface temperature, precipitation and height at 500 hPa. The hindcasts of the temperature and precipitation in summer for the lead time form 1951 to 1992 are made. It is shown that the prediction skill of the model is quite well, nevertheless, a new approach of the climate prediction is demonstrated.
Development and Real Time Application of Nonhydrostatic Mesoscale NWP System for Beijing Area
Wang Jianjie, Wang Yingchun, Cui Bo, Lu Duanjun, Yu Wei, Guo Xiaorong, Chen Dehui
1999, 10(4): 384-393.
A big progress has been made on the development of the mesoscale numerical weather prediction (NWP) system for Beijing area, a joint project of National Meteorological Center (NMC) and Beijing Meteorological Bureau (BMB). The basin of the PSU/NCAR’s nonhydrostatic mesoscale model version 5 (MM 5), an experimental mesoscale NWP system for Beijing area (BJ-MM 5 V.1) was created, in which the model is two-way nested with 45 and 15 km horizontal resolution for coarse and fine mesh, respectively, and 23 σ layers in vertical; and it is run on the parallel environment of IBM/SP2 with 24 nodes for 36 h prediction, while 2 h and 20 min in computing time is able to meet the time requirement for real time operational application. The BJ-MM5 V. 1 is linked with the data resources of the NMC as well as the data set of intensive surface observation over Beijing area. And encouragingly, it was run stably in real time and its products were referenced by the weather office of BMB for weather forecasts during the whole summer of 1997. The verification results indicate that the model can predict reasonably the spatial and temporal distribution of precipitation.
Numerical Study on the Effects of Underlying Surface Forcing on Torrential Rain Process over Beijing-Tianjin-Hebei Region
1999, 10(4): 436-444.
The torrential rain process on July 23, 1992 over Beijing-Tianjin-Hebei region is simulated by using the model MM4. With the model products of high temporal and spatial resolution, some kinds of numerical experiments employing numerical models Mass & MM4 are designed here to demonstrate the effects of underlying surface mechanical and thermal forcing on the torrential rain process. It is pointed out that the strong upward motion associated with surface convergence forced by underlying surface is the trigger mechanism of the torrential rain process.
Diagnosis on the Impact of Middle Troposphere Circulation Pattern over the Qinghai-Xizang Plateau on the Track of Typhoon over West Pacific
Xu Jing, Chen Lianshou, Xu Xiangde
1999, 10(4): 410-420.
There is a close relation between the variation of middle troposphere synoptic system over the Qinghai-Xizang Plateau and movement of typhoon over West Pacific, and the relation is studied with the observation study and dynamical diagnosis from the point of view of downstream development and interaction between mid-latitude and low latitude. 25-year statistics results from 1970 to 1995 indicate that the relations between middle troposphere circulation patten over the Plateau and the track of typhoon over West Pacific are as follows: When low-pressure system on 500 hPa isobaric surface occupies middle troposphere over the Plateau, it is beneficial to typhoon’s Westward movement; on the contrary, high-pressure system on 500 hPa isobaric surface is always beneficial to typhoon recurvature. The results of dynamical diagnosis show the physical mechanism of impact of synoptic system over the Plateau on downstream synoptic system, that is, the transport of disturbance kinetic energy over the upstream Plateau makes the downstream trough developed. And then it affects the steering flow of typhoon. Because of existence of the ridge over the Plateau, the eddy kinetic energy transport channel moves to the north. On the contrary, trough exists over the Plateau, so the eddy kinetic energy transport channel moves to the south. The southerly wind in front of the trough over the Plateau together with the southerly wind at the east part of typhoon transports low potential vorticity of low latitude into subtropical high. That is beneficial to development of subtropical high, and then subtropical high affects typhoon’ s movement. These results fully reflect the impact of interaction between mid-latitude and low latitude on synoptic system
Estimation of Albedo and Net Radiation for Maize Canopy
Lu Houquan, Yu Guirui, Nakayam a Keiich
1999, 10(4): 421-427.
According to the characteristics of maize canopy, the plant, characteristics values including height of plant, mean leaf density and the rate of farmland coverage were chosen as the plant parameters, i. e. the multiple coefficient of vegetation to describe the feature of maize canopy based on the experiments in the maize fields for three summers from 1994 to 1996. By using the multiple coefficient of vegetation as a factor, an estimation method for albedo and net radiation of maize canopy was proposed, and the good results were obtained.
The Score Skill and Interpretation of Monthly Dynamic Extended Range Forecast
Chen Lijuan Li Weijing
1999, 10(4): 486-490.
Using monthly dynamic extended range forecast (DERF), the 500hPa geopotential height fields are evaluated with three kinds of scores. The skill of momthly DERF is generally better than that of persistence and climate forecast. The products of DERF can be used as a reference in prediction, but still do not meet the demands of the operational system. Further analyzing 500 hPa geopotential height, it is found that some circulation characteristics are well predicted, their forecasting skills are higher than that of 500 hPa. Some studying results and experiences show that there are better correlations between circulation characteristics and element forecast which could be used in operational prediction. This provides another way for interpretation of DERF Products.
Controlling of the Photochemical Smog
Ji Fei, Su Wenying, Qin Yu
1999, 10(4): 491-497.
Three experiments of emission sources cutting down were carried out to find out the best way for controlling the photochemical pollution by using the coupling model of MM 5 and RADM. The results show that when the ratio of NMHC/NOx is large, the cutting down of surface NOx source emission is the most efficient way to decrease O3 in atmosphere while the cutting down of NMHC is most efficient way to decrease PAN in atmosphere, and cutting down of NMHC and NOx at the same time is best way to control the atmospheric photochemical pollution.
Research on Railway Flood Disasters and Assessment Models in China
Zhang Qing Huang Chaoying
1999, 10(4): 498-502.
The characteristics of railway flood disasters in China are analyzed, and the statistical models of the whole country and four main railway bureaus (Chengdu, Zhengzhou, Harbin and Shenyang) are established, respectively by using line break time and frequency from 1980 to 1995 and total days of heavy rain and torrential rain at the same periods. All these efforts would lay the base for assessing the impacts of abnormal climate quantitatively on railway transportation.
EOF Model for Drought Prediction in Northwest China
Zhang Cunjie, Dong Anxiang, Guo Hui
1999, 10(4): 503-508.
Based on empirical orthogonal function (EOF) analysis, an EOF model suitable for drought prediction in Northwest China was designed. Forecast experiment based on EOF model was carried out using the mean generating function method, multiple regression method and canonical correlation analysis (CCA) method. The results show that there is a specified predictive capability for the drought in Northwest China.
Diagnostic Study on Impact of Sea Surface Temperature Anomalies over Tropical and Mid-latitude Pacific on Summer Low Temperature Cool Damage in Northeast China
Zheng Weizhong
1999, 10(4): 394-401.
By using the data set of the surface air temperature of 23 stations in Northeast China during the period of 1951—1997, mean monthly sea surface temperature (SST) in Pacific from 1950 to 1996 and global mean monthly wind fields from 1980 to 1994, the spatial and temporal features and its variations for summer low temperature cool damage in Northeast China are analyzed. The possible relationship and the mechanism of impact between SST anomalies in the regions of Pacific and the low temperature cool damage are also studied. The results show that the first three eigenvalues obtained by the EOF analysis (84.28% of the total variance) can basically explain the summer temperature anomalies in Northeast China. The temperature anomalies reconstructed by those three eigenvalues have three dominant scales on 3—4 years, 6—8 years and quasi-16 years. Among them, 6—8 years’ oscillation is the strongest. On inter-decadescale, three appears a jump of the temperature from cooler to warmer around 1997. The warm pool of tropical West Pacific (140° E—180°, 10° S—10° N) is a key area that affects the summer low temperature in Northeast China. The SST anomalies in last winter over that is a strong signal which could be used to predict the summer low temperature cool damage. Another key area is mid-latitude West Pacific (130° E—180°, 10°—30° N) where the SST anomalies in last spring are also closely related with summer low temperature in Northeast China.