Vol.15, NO.6, 2004

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AN AEROSOL POLLUTION EPISODE IN HONG KONG WITH REMOTE SENSING PRODUCTS OFMODIS AND LIDAR
Li Cheng cai, Lau Kai-hon, ao Jietai, Chen Aizhong
2004, 15(6): 641-650.
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Abstract:

Aerosol optical depth data from MODIS visual channels and aerosol extinction coefficient profiles from MPL LIDAR are used to study an aerosol pollution episode in the Pear River Data on June 18 and 19, 2003. The regional distribution pattern of aerosol optical depth and the evolution of aerosol extinction coefficient profiles in mixing layer form remote sensing methods are given to demonstrate that the air pollution case caused by weak stable high system has a regional coverage and contributes to the surface air pollution in Hong Kong. The results show that satellite and LIDAR remote sensing provide new ways in air pollution study.
ATMOSPHERIC CORRECTION OF VISIBLE TO MIDDLE-INFRARED OF EOS-MODIS DATA OVER LAND SURFACES BY USING 6S MODEL
Zhang Jie, Wang Jiemin, Guo Ni
2004, 15(6): 651-657.
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Abstract:
Atmospheric correction of visible to middle-infrared of MODIS data over land surfaces is done using 6S model. There are two processes of the correction, first, objective is assumed as the Lambertan surface, then bi-directional BRDF model Roujean is operated. Comparing the corrected result with the MODIS airborne simulator (MAS) which MODIS research group using in experiment, the result shows that there is consistency characteristic on their variety trends. The reflectance of near-infrared band 2 and blue band 3 are falling, but the red spectral band 1 is rising by operating atmosphere corrected. INDV is higher and Iev is lower after atmosphere is corrected, the largest value of variety are 0.104 and 0.005.
MICROPHYSICAL ADJUSTMENTS USING REFLECTIVITY OF DOPPLER RADAR FOR MESO-SCALE MODEL
Li Yo ngping, Yuan Zhaohong, Wang Xiaofeng
2004, 15(6): 658-663.
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Abstract:
A simple analysis scheme proposed by Brewster K in 1996 is used to retrieve cloud microphysical variables such as water mixing ratio and rainwater mixing ratio of cloud, as well as humility variable of the model air from Doppler weather radar's reflectivity. The initial fields of meso-scale numerical model derived from model's data assimilation system can include cloud microphysical messages and show where the air is saturated within model space. A numerical experiment for a rainfall process near Maanshan City of Anhui Province in China on June 19 of 2002 is performed by the Advanced Regional Prediction System (ARPS) based on this scheme. The background fields and boundary conditions come from the globe model's output of AVN in NCEP, and a 600 km×600km domain is setup with 2km×2km horizontal resolution, and 21 layers in vertical. Results show that 1 hour's forecast of the atmospheric composite reflectivity with ARPS matches the detailed echo picture observed by the radar at target time, and the non-uniform distribution of precipitation with some rainfall clusters matches the non-uniform distribution of echoes with several strong clusters. The clouds represented by cloud microphysical variables can be tracked both in horizontal and vertical directions from initial time to the time of forecast, and their changes are consistent with the observed radar reflectivity. Also some of the meso-scale wind structures with convergence and divergence appear near the strong echoes, which result from atmosphere thermodynamic adjustment to the clouds. Comparatively, the forecast doesn't match the observation if not considering such scheme including radar reflectivity within data assimilation system for initial field of the model. So it seems that this analysis scheme used here would be helpful for numerical nowcasting of the precipitation.
UNMIXINGMETHOD APPLIED TO NOAA-AVHRR DATA FOR SNOW COVER ESTIMATION
Yan Hao, Zhang Guoping
2004, 15(6): 665-671.
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Abstract:
Based on the spectral analysis of snow, soil, vegetation and cloud, it is pointed out that the first two channels of traditional NOAA-AVHRR have troubles to distinguish snow from cloud, and the low reflectance of snow in 1.6 μm infrared channel can be used not only to distinguish snow from cloud but also to supply more spectral information to extract snow cover. So the principal components analysis (PCA) was made to AVHRR data, and it was found that the PCA-transformed first two principal components (PCA1, PCA2) contributes about 99% cumulative variance. And the scatter plot to these components was analyzed and the endmembers were given. Also, two different methods were adopted to extract snow cover by using spectral linear mixing model, and results are highly consistent, which indicate that the unmixing method is an effective way to retrieve snow cover parameter.
Preliminary Analysis on Parallel Comparison of GPSO3 and Vaisala Ozonesondes
Wang Gengchen Kong Qinxin Xuan Yuejian Wan Xiaowei Chen Hongbin
2004, 15(6): 672-680.
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Abstract:
Parallel comparison of GPSO3 (made in China) and Vaisala (made in Finland) ozonesondes was carried out at Atmospheric Observing Experimental Base, CMA, in Beijing during the period of Jan 11—23, 2002, 7 pairs of ozonesondes were launched. Comparison results show a relative good consistence in the ozone vertical variation characteristics obtained by both type of ozonesondes in general. The average relative error between ozone concentrations at 12—27 km in the atmosphere measured by the both type ozonesondes is less than 10%, while at altitudes below 12 km and above 27 km, the measured ozone concentration by GPSO3 sonde is higher than that by the Vaisala one. Comparison method is introduced, comparison results of some ozone variation futures are analyzed, a possible influence of sonde ascending speeds during soundings on the comparison results is discussed as well.
ANALYSIS OF PRECIPITATION AND RIVER FLOW IN THE HUAIHE RIVER BASINS DURING THE SUMMER OF 2003
Bi Baogui, Jiao Meiyan, Liao Yaoming, Xu Jing
2004, 15(6): 681-687.
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Abstract:
In terms of intensive observed precipitation data and hydrological information of the Huaihe River Basins (referred as HRB Hereinafter), the spatial-temporal distribution of precipitation and climatic features during the summer of 2003 are analyzed. Comparison is made with the year of 1954 and 1991 for the same period. Results show that 7 weather processes occurred with the total precipitation, river-level and flow are more than those of 1991, but less than 1954. Also, flood peak reduced with time. Main rainfall features in the target regions in 2003 are stable rain-belt, intensive and explosive storm-rainfall. More precipitation during spring of 2003, southward-shifted subtropical high in July 2003, antislope in the middle HRB are important causes for the whole HRB over danger water-level.
PRECIPITATION IN THE YANGTZE RIVER DELTA FIELDS CAUSED BY TROPICAL CYCLONES LANDING IN THE SOUTH CHINA SEA
Chen Shuqin, Huang Hui, Shao Chunhai
2004, 15(6): 688-695.
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Abstract:
The maximum precipitation in the Yangtze River Delta which were caused by the tropical cyclones landing in the South China Sea in 1949—2000 were studied. The probability of precipitations above 50 mm was worked out when there was a tropical cyclone in the South China Sea. It is about 60 percents. A wavelet transform about the frequency of the tropical cyclones was performed. The results show that this series has notable oscillations and the periods vary in some regulations. As results of a cross power spectral analysis about the frequency series of the tropical cyclones and the sum series of the subtropical high area indexes of July, August and September, the two series have quasi-two-year and quasi-five-year coupled oscillations. The anomalies in the West Pacific, the Atlantic and the North Pole were found out when the Northern Hemisphere 500 hPa height data of anomalistic years were analyzed.
SPATIAL VARIATION OF PRECIPITATION TREND AND INTERDECADAL CHANGE IN JIANGSU
Deng Ziw ang, Zhou Xiaolan, Chen Haishan
2004, 15(6): 696-705.
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Abstract:
By analyzing the monthly rainfall (R) series of the 60 weather stations for the 1961—2001 period, monthly, seasonal and annual precipitation abnormity percentages (RAP) were calculated. Based on these the spatial patterns of seasonal and annual precipitation trends and interdecadal changes in Jiangsu Province were investigated. Results show that: (1) there are significant positive (negative) trends in January, March and June (April and September); (2) annual rainfall increased in the south, decreased in the north and weakly varied in the middle; (3) seasonal mean precipitation decreased in most parts in spring, increased in southern regions and decreased in northern districts in summer, decreased in most areas in autumn and increased all over the Province in winter; (4) the abnormity percentage sign variation types of the four decadal average are "--+ +" in the south, " + +--" in the north and "+--+" or " +-+-" etc transition types in the middle regions of the Province respectively for annual precipitation. For spring precipitation, they are "-+-+" in north, " +--+" in the middle, " +---" in south and " + +-+" in Xuzhou and yanchen districts. For summer rainfall, they are "+ +--", "+-+-", "+--+", "-+-+" and "--+ +" form north to south. For autumn rainfall, the type "+ +--" appears at almost all stations in the Province. And for winter precipitation the type "--+ +" appears in large area in the south and the east of the Province, the other comparative frequent types such as "-+ + +", "--+ +", "-+-+" and "---+" etc appear mainly in the west.
COMPARISON EXPERIMENT OF IMPROVEMENT IN HLAFS OPERATIONAL FORECAST SYSTEM
Yan Zhihui, Zhu Zheng hui, ZHao Min, ZWang Yu
2004, 15(6): 706-711.
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Abstract:
The main study purpose is to improve the precipitation prediction. Based on the operational limited area forecast model in National Meteorological Center, a simple mixedphase explicit cloud scheme was implanted, in which the freezing of cloud/rain water and melting of snow were considered and the snow as well as super-cooling water was allowed to exist under 0℃ in the model atmosphere, and the horizontal resolution was increased from 0.5o×0.5o to 0.25o×0.25oin latitude and longitude. Depending upon the improved model, the corresponding assimilation system was set up, and comparison experiment was implemented. The verification to precipitation predictions between two schemes with real-time data show that precipitation area predicted by new scheme is better than old scheme obviously, and also, the precipitation intensity in the precipitation central area is strengthened and closed to the observation.
A REMOTE METEOROLOGICAL DATA COLLECTION AND TRANSMISSION SYSTEM BASED ON GPRSWITH ITS APPLICATION
Liu Cong, Gu Jian, Wu Guoping, Yuan Chengsong, Huang Shicheng
2004, 15(6): 712-718.
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Abstract:
After the comparison among various methods of remote data real-time transmission used to automatic meteorological observation stations, a scheme of remote meteorological data collection and transmission system based on GPRS is suggested. By the means of the little data stream, it achieved the real-time collection and transmission of the autometeorological observation data, likewise saved the outlays for operating and monitoring the system and improved the valid time of data transmit. The system was successfully applied to meteorological environment monitoring and forecasting system during the construction period of Su Tong Changjiang River Bridge.
DIFFERENCES BETWEEN DATA OF AUTOMATIC AND MANUAL OBSERVATION
Hu Yufeng
2004, 15(6): 719-726.
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Abstract:
The many factors caused data differences of automatic and manual observation were described, including difference of measuring principles and observation method, differences of measuring time and space, difference of sampling mode and algorithm, difference of time level, and so on. Comparison between two objective data of basic meteorological elements, such as air pressure, temperature, wind direction, wind speed, precipitation, humidity etc, was conducted. It is found that observation results of automatic weather station are more objective and scientific than that of manual observation. It has a prominent advantage at an automatic weather station measuring air pressure, temperature, wind direction, wind speed. On measuring rainfall amount, although the automatic weather station has a defect as to provide accumulative rainfall amount, it can provide betimes message of rainfall amount, and so has its superiority on weather forecasting. On humidity measuring, although it cannot get a satisfactory observation in the circumstance of high temperature and high humidity, but it has an advantage in its bounds of moderation.
THE CONSTRUCTION Of NATIONAL METEOROLOGICAL ARCHIVAL AND RETRIEVAL SYSTEM
Shen Wenhai, Zhao Fang, Gao Huayun, Gao Feng, Ma Qiang
2004, 15(6): 727-736.
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Abstract:
The system requirements of NMARS (National Meteorological Archival and Retrieval System) and the function designs for the system are suggested. Based on the technique investigation and analysis, the technique schemes for the implementations of those functions are also given: the RDBMS integrated with the external file system is used for data management; the HSM (Hierarchical Storage Management) architecture is adopted for storage management, including the storage management of RDBMS; the program-retrieval function is provided for data retrieval. In terms of the middleware technology, the realization of the function is based on the B/S (Browser/Server) architecture; the HPSS (High Performance Storage System) solution is applied in the storage pool issue of the HPC (High Performance Computer) cluster system composed of several HPCs with different architecture; the RDB (Real-time Database) system and IDB (Integrated Database) system are designed to solve the contradictory between the standardization storage of the meteorological data and the performance requirements of the real-time operational system; the corresponding specifications are strictly followed in software development.
THE COLOR SCANNING DIGITIZING PROCESSING SYSTEMOF PRECIPITATION AUTOGRAPHIC RECORD PAPER
Wang Bomin, Lu Yongping, Zhang Qiang
2004, 15(6): 737-744.
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Abstract:
The purpose of the color scanning digitizing processing system of the precipitation autographic record paper is to realize converting data from color scanning graph to the precipitation intensity per minute. The design thought, framework and functions of the computer processing system are introduced. The master functions of this system include the pretreatment of the precipitation autographic record paper, paper scanning, scan checking-up, precipitation curve collecting and precipitation intensity data conversion. The key technologies in system design causing the reader to all-round know the main content and the characters of this system are also expounded. The representative technologies include the precision analysis and the scan resolution of digitizing the scanning graph, the technique of automatic tracking and collecting the precipitation curves, the technique of data processing of digitizing graph, the synchronous orientation display technique etc. The color scanning digitizing processing system of precipitation autographic record paper has been applied to operations in Provinces.
STUDY ON THE AGROMETEOROLOGICAL INFORMATION SHARE AND DELIVERY TECHNOLOGY BASED ON WEBGIS
Zhuang Liw ei, Liu Gengshan, Wang Shili, Wang Jianlin
2004, 15(6): 745-753.
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Abstract:
Relying on the communication network of observation stations in the meteorology department all over China, the research on agrometeorological information share and release technology based on WebGIS is developed. The agrometeorological information is standardized basing on the standards of meteorology industry and network data, then the network share database required by WebGIS application system is established using SQ L Server 2000, and the agrometeorological information service WebGIS platform is set up using IIS and ArcIMS (Internet Map Server). The application software about developing server applying Java Script、ArcGIS and management tool of ArcIMS Manager. The two-way search function from attribute to space and from space to attribute of agrometeorological information as well as thematic map analysis function of agrometeorological information are realized on client which can supply detailed、abundant and high quality agrometeorological information services for users.
A BRIEF REVIEWON THE DEVELOPMENT OF NOWCASTING FOR CONVECTIVE STORMS
Chen Mingxuan, Yu Xiaoding, Tan Xiaoguang, Wang Ying chun
2004, 15(6): 754-766.
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Abstract:
Nowadays, the nowcasting technique and research for convective storms have an exciting advancement along with the rapid development of Doppler weather radar and many else meso-and micro-scale meteorological observation instruments. At present, main nowcasting techniques comprise three aspects: identification, tracking and extrapolation forecast, numerical model forecast, knowledge-based forecast technique. Cross-correlation technique and echo feature identification and algorithms are well-performed extrapolation techniques mainly based on weather radar data and are utilized by many operational nowcasting systems, but there are very short forecast period and low accuracy. Now the techniques that assimilate radar, mesonet and micro-scale data into fine meso-and micro-scale numerical models to nowcast initiation, evolution and dissipation of thunderstorms are very promising and robust. Techniques are progressing rapidly but not mature for operation. Knowledge-based nowcasting techniques are more observation-based. They combine and analyze a variety of fine meteorological data sources, including radar and satellite data, then theorize conceptual models of initiation, evolution and dissipation of thunderstorms, especially, the close relation between boundary layer convergence lines and enhanced convection, as well as integrate fine numerical models outputs initiated with or without radar data and extrapolation technique results, then build expert system of thunderstorm nowcasting to gain information about not only the development but also the initiation and dissipation of thunderstorms and convective rainfall. Verification and qualitative assessment of forecast also show that the expert systems outperform all other techniques for operational nowcasting thunderstorms and convective precipitation in accuracy and period. The expert systems are one of the primary techniques for nowcasting convective storms evolution in the near future. Auto-Nowcaster developed by NCAR is one of the state-of-the-art expert systems for nowcasting thunderstorms.
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