Vol.13, NO.2, 2002

Display Method:
MODELINGOF ENERGY BUDGET USING SIMPLE BIOSPHERE MODEL VERSION 2(SiB2) OVER TIBETAN NAQU PRAIRIE
Gao Zhiqiu, Bian Lingen, Cheng Yanjie, Zhang Yabin, Wang Jinxing
2002, 13(2): 129-141.
Abstract:
SiB2 (Simple Biosphere model version 2) is adopted to simulate surface energy budget in offline mode with certain atmospheric forcing values measured in the near surface observations taken over in the Tibetan short grass prairie as a part of the GAME/Tibet (DEWEX Asian Monsoon Experiment/Tibet) experiment. On the condition that all parameters are reasonably fixed, the simulated net radiation, latent heat flux and soil heat flux are shown to be basically in agreement with observations with their relative errors being 8% (underestimated), 6% (underestimated), and 3% (underestimated), respectively; in meantime, SiB2 overestimates sensible heat flux by 40%. The detail analysis about energy components is conducted.
CONVECTIVE ACTIVITIES IN THE ATMOSPHERIC BOUNDARY LAYER OVER THE PLATEAU IN WESTERN CHINA
Chen Zhi, Zhou Mingyu, Qian Fenlan, Li Shiming, Su Lirong, Xu Xiangde, Chen Lianshou, Wang Jizhi
2002, 13(2): 142-155.
Abstract:
The convective phenomena in the atmospheric boundary layer on the Tibetan plateau are analyzed based on data Doppler sodars, the radiosonde system whit high resolution, and satellite images during the second field experiment of atmospheric sciences on the Tibetan Plateau in 1998. Strong convective activities were detected by sodars. The vertical velocity in the thermal plume exceeds 1 m/s. The time scales of the convective plumes are about 1.4 hours and they appear as organized mesoscale and small-scale turbulent motions. The physical mechanisms of the developing and maintaining of strong convection in the plateau boundary layer can be described as following. The strong convective activities are related with the intense total radiation in the plateau area, the strong baroclinity in the plateau boundary layer induced by the inhomogeneous heat status of the underlying surface caused by the complicated terrain, and the advection effects in the plateau boundary layer. With these effects, strong organized large eddies can occur in the boundary layer. The thermal plumes formed from the eddies develop upward and can be combined to from large thermal convective cells. Some convective cells can be combined with convective cloud clusters, in which the full convective mixture occurs when these eddies exceed the condensation level. The latent heat during the condensation process can help the cloud clusters to develop further, and the cloud clusters can become larger cloud groups, which can be seen in the satellite images.
A COMPOSITE DIAGNOSTIC STUDY OF HEAVY RAIN CAUSED BY THE NORTHEAST COLD VORTEX OVER SONGHUAJIANGNENJIANG RIVER BASIN IN SUMMER OF 1998
Sun Li, An Gang, Gao Zong ting, Tang Xiaoling, Ding Li, Sheng Baizhu
2002, 13(2): 156-162.
Abstract:
Nine typical heavy rain events caused by the northeast cold vo rtex over Song huajiang-Nenjiang basin in China have been chosen and their composite of physical variables w ere also done.The results show that the blocking high over East Asia, the w est Pacif ic subt ropical high, the no rtheast cold vo rtex and summer monsoon moisture transportation play quite impo rtant roles in the persistent heavy rain over the Song huajiang-Nenjiang region.The special horizontal and vertical st ructures of the cold vortex itself result in the heavy rain mainly occurring to the east of the cold vortex center.
DYNAMICAL EFFECTOF BOUNDARY LAYER CHARACTERISTICS OF TIBETAN PLATEAU ON GENERAL CIRCULATION
Zhuo Ga, Xu Xiang de, Chen Lianshou
2002, 13(2): 163-169.
Abstract:
The effect of boundary layer height (BLH) of Tibetan Plateau on atmospheric circulation is studied by the communi ty climate model (CCM3), and the observation result s of second scientific experiment on the Plateau is also combined.Evidence shows that BLH contributes to the st rong development of vert ical motion at the southeast part of the Plateau and the Yangtze River valley, along w ith air flow enforcement of convergence (divergence) at the lower (upper) level.Deepen BLH is also beneficial to remarkable increase (decrease) in cloud and precipi tation in the Yangtze River valley and the Yellow River area.
REGIONAL DATA ASSIMILATION SYSTEM OF HUAIHE BASIN EXPERIMENT (HUBEX)
Zhu Zongshen, Ma Qingy un, Hao Min, Guo Xiao rong, Tao Shiwei, Li Zhiyuan, Wang Jianjie, Hu Ming
2002, 13(2): 170-178.
Abstract:

The Regional Data Assimilation System (RDAS) of Huaihe Basin Experiment (HUBEX) is presented. The RDAS is an intermittent assimilation system in which an assimilation cycle includes four analyses in a daily period. Both the first guess fields for the cold starting of the system and the boundary conditions for the assimilation model are supplied by products of the global model system. The RDAS consists of quality control, σ-surface optimum interpolation objective analysis, nudging initialization, mesoscale assimilation model forecast and post-processing. The observational data from the Global Telecommunication System (GTS), HUBEX intensive observation period (IOP) and National Satellite Meteorological Center are assimilated. Finally, a heavy rain process in June 24—28, 1998 is tested using the RDAS.

THE PRELIMINARY EXPERIMENTON DERIVING INTEGRATED ATMOSPHERICWATER VAPOR FROM GROUND-BASED GPS
He Ping, Xu Baoxiang, Zhou Xiuji, Wang Hongyan
2002, 13(2): 179-183.
Abstract:

The field experiment named "HUAMEX" was conducted in China from May to June 1998. In this experiment, a regional GPS-network that included three ground-based GPS receiving stations (Shantou, Yangjing and Haikou) was established to estimate integrated atmospheric water vapor (IWV) continuously. The comparison of IWV estimates derived from GPS and radiosonde observations for a 51-day period at Shantou station is given. Both have an average bias of 6.5 mm, and the root-mean-square difference is 4.3 mm. The IWV derived from GPS varies with time and it has an obvious period of 7.2 days in average. Moreover, the IWV derived from GPS is compared with the observed surface integrated precipitation hour by hour. The comparison of GPS-derived IWV and integrated surface precipitation indicates that there is a good coincidence between them. The variation period of GPS-IWV is similar to that of surface precipitation. From the time-series of IWV estimated from GPS, the accumulating and releasing processes of water are obvious.

FEASIBILITY EXPERIMENTS ON SOUNDING WATER VAPOR AMOUNT WITH 940 nm SPECTRAL BAND
Huang Yibin, Do ng Chaohua
2002, 13(2): 184-192.
Abstract:
The water vapor amount is simulated through its statistical relation to the ratios of reflectance in several channels, which are selected and grouped from the 940 nm weak water vapor absorption band and the vicinal window region. The simulation results of water vapor amount have an average relative error of 6% by compared with the independent radiosonde observation.
CLIMATE CHARACTERISTICS OF SANDSTORM IN CHINA IN RECENT 47 YEARS
Zhou Zijiang, Wang Xiw en, Niu Ruoyun
2002, 13(2): 193-200.
Abstract:
Based on the available observation data from 681 meteorological stations in China in 1954—2000, the temporal and spatial distribution characteristics of sandstorms in China in recent 47 years have been analyzed. The results show: (1) The arid and semi-arid regions in north part of China are sandstorm's easily influencing area, and Northwest is high-incidence area. (2) The characteristics of sandstorm's daily variation and seasonal variation are significant. (3) In recent 45 years, the frequency of sandstorms increased at a few stations in Qinghai province, Xinjiang and Inner Monglia, but decreased in the most northern parts of the country. (4) The number of violent sandstorm events in 1980's and 1990's is significantly less than that in 1950's and 1970's at Minqin, Gansu and Hetian, Xijiang. (5) The number of sandstorm events in 2000 is more than the average in 1990's, but less than the average in 1956—2000 in North China and the east part of Northwest China. (6) The interannual change and secular trend of sandstorms are consistent with the variation of strong wind. The correlation coefficient between sandstorm and strong wind is generally over 0.5 at a single station.
THE DROUGHT RISK ASSESSMENT AND DIVISION OF WINTER WHEAT IN SHAANXI PROVINCE
Zhu Lin, Ye Dianxiu, Chen Jianwen, Guo Zhaoxia, Li Meirong
2002, 13(2): 201-206.
Abstract:
Based on the risk analy sis principles of nature disasters, the reduction probability of winter wheat yield resulting from drought hazard during whole grow ing season, combined with the density of damaged system and level of production, and the capability of drought-resistant in every counties are discussed.The GIS-based droug ht risk division of winter wheat in Shaanxi Province is made according to the grading standards using the risk indexes as division target.
A NEW SCHEME FOR IMPROVING THE ACCURACY OF NUMERICAL PREDITION —RETROSPECTIVE TIME INTEGRATION SCHEME
Feng Guolin, Cao Hongxing, Gu Xianqian, Chou Jifan
2002, 13(2): 207-217.
Abstract:
To put more information into difference scheme of a differential equation for making an accurate prediction, a new kind of time integration scheme, known as the retrospective scheme, is proposed on the basis of the memorial dynamics. Stability criteria of the scheme of an advection equation in certain conditions are derived mathematically. The computations for the advection equation have been conducted with its retrospective scheme. It is shown that the accuracy of the scheme is much higher than that of the leapfrog difference scheme. The retrospective time integration scheme can be applied to oceanography, hydrology, environmental sciences, aviation and so on.
THE LATITUDINAL DISTRIBUTION OF CLIMATIC CHARACTERISTICS ON TROPICAL CYCLONE ACTIVITIES IN THE WNP
Lei Xiaotu, Chen Lianshou
2002, 13(2): 218-227.
Abstract:
Using the tropical cyclone (TC) yearbook data from 1949 to 1998, the latitudinal distribution of TC movement in the Northwest Pacific is analyzed. They include the climatic characteristics of TC genesis, active, extratopical transition (ET) and disappearance position; the ratios of TC north-toward moving, ET and disappearance; and the average intensity and movement.
A PARALLEL ENSEMBLE NUMERICAL WEATHER PREDICTION SYSTEMON THE SHENWEI
Zhang Yi, Wang Xiufeng, Fu Shenxin
2002, 13(2): 228-231.
Abstract:
The development background, structure and main technical characteristic of a parallel ensemble numerical weather prediction system on the Shenwei massively parallel processor system are described. The system is composed of seven subsystems: preprocessing, data assimilation, ensemble initial data generation, numerical weather prediction, post-processing, product generation and visual real-time monitoring control. The singular vector is used to create initial perturbation at the T21L19 resolution and the forecast subsystem is at the T106L19 resolution. The number of ensemble members is 32.
PARALLEL ALGORITHM IN SW ENSEMBLE NUMERICAL WEATHER PREDICTION SYSTEM
Zhang Yi
2002, 13(2): 232-238.
Abstract:
The parallel algorithm and the implementation of the SW ensemble numerical weather prediction system are described. Performance results indicate that the parallel algorithm makes the best use of the CPU resources of SW and acquires higher efficiency.
PARALLELIZATION IMPLEMENTATION OF CHECKING DATA PROCESSING IN ENSEMBLE PREDICTION SYSTEM
Wang Huiling
2002, 13(2): 239-244.
Abstract:
The SW ensemble numerical weather prediction sy stem is a real-t ime operational sy stem developed at the plat form of the supercomputer Shenwei made in Chima.The checkout subsystem is its important component.The parallelization implementation and the parallel ef ficiency of checking data processing in the SW ensemble numerical w eather prediction sy stem are int roduced.
THE DESIGN AND IMPLEMENTATION OF SW VISUAL REAL-TIME MONITORING CONTROL SYSTEM
Yu Feng
2002, 13(2): 245-249.
Abstract:
The visual real-time monitoring control scheme with error accommodation function in accordance with the characteristics and possible problems in running the SW parallel ensemble numerical weather prediction system is presented.
MASS DATA MANAGEMENT IN SW ENSEMBLE NUMERICAL WEATHER PREDICTION SYSTEM
Zhang Yi
2002, 13(2): 250-253.
Abstract:
The implementation of mass data management in SW ensemble numerical weather prediction system in respect of data file naming, data file access and input/output management is described.
PARALLEL IMPLEMENTATION OF THE OBJECTIVE ANALYSIS SCHEME IN ENSEMBLE PREDICTION SYSTEM
Leng Tingbo
2002, 13(2): 254-256.
Abstract:
The parallel processing of the Objective Analysis subsy stem in "Shenw ei"massively parallel processing system in respect of serial prog ram analysis, parallel scheme selectio n and algo rithms implement is int roduced.The application performance results are given.