Abstract:A vortex with heavy rainfall typical of disturbance over the Meiyu front occurred in the period of July 31 to August 1, 1980 The development and structure characteristics of this meso-β scale low are studied. The low bears clear baroclinity with the front structure different from heat lows in the area. The wind velocity and thermodynamic fields of the low are asymmetric with the strongest ascending motion at its warm sector. Based on the formula K=K_Ψ+K_χ-J(Ψ, Χ), we have calculated the kinetic energy of the divergent and rotational parts of the winds and their conversion. Investigation of the kinetic energy feature of the low suggests that the transfer from K_χ to K_Ψ occurs in its whole life cycle, especially in lower levels. The terms of f▽Ψ·▽χ and ▽²Ψ·▽Ψ·▽χ play a mojor role in the conversion similar to the situation in explosive cyclogenesis.

Abstract:In the light of Wuhan and Yichang digitized radar echo data obtained during 1987-1989, the heavy rain occurrences in Hubei province in spring and summer are classified iuto five types, namely, meso-α scale heavy rain cloud cluster, cold front heavy rain, convective rain band in warm areas, landing typhoon, and multicell or snpercell. some eharacteristics of theirmesoscale structures and evolution. processes are described in this study.

Abstract:By use of the geostationary satellite pictures in June-August, 1979-1986, the formation, initial location, track and duratioa of convective cloud clusters over the middle reaches of the Changjiang River, on the one hand, and the relationship between the cloud clusters and the synoptic-scale cloud system, on the other, are statistically analyzed. The 0-6 hr rainstorm forecasting flow diagram is suggested.

Abstract:By using the radar equation developed by the authors, the differences in the probe results obtained in different forms of azimuthal integration and different processing methods of gridding with the dual digital processing system of the same weather radar are theoretically simulated. Some major conclusions are reached as follows. As compared with the non-azimuthal integration, the 1/2 and 3/4 exponential weighted azimuthal integration makes the precipitation echo intensity, the reflectivity factor and the precipitation intensity distribution curve move successively in the direction in which radar beams move. Their amplitudes decrease accordingly but the decrease of amplitudes are rather small, and the differences of reflectivity factor and precipitation rate are small on the side where beams move in and large on the side where beams move out. After coordinate transferring by different data processing methods, there might be a difference of over 10 dBz On either side of the intensive echo center in the 2×2 km² grid.

Abstract:A heavy rain in an MCC occurred in the middle reaches of the Changjiang River in the period of June 10-11, 1988 was analyzed in much detail by using the synoptic-dynamic method, exposing the characteristics of the clusters, the environment flow field and the dynamics and thermodynamics of the event.

Abstract:In this paper, analysis is performed of the thermodynamic and dynamic effects of the unusual topography in the experiment area of Hubei province, with the obtainment of the topographic wind circulation system in its average meaning, corresponding to the topographic scale. The regularities of its evolution and the temporal and spacial characteristics of the divergence field are thus revealed. It is found that the cony ergence field of topographic wind is related to the precipitation in the area. In the end, discussions are made of the comprehensive effects of the temporal-spaeial characteristics of the temperature-pressure anomaly field and the topography in the experiment area on the meteorological element field.

Abstract:On the system engineering principle, studies are made of the functions, requirements and two alternative computer networks of the operational monitoring and nowcasting system for the severe convective weather during the experiment period of 1990. Finally, a preliminary design is proposed for the real-time operational severe convective weather monitoring and nowcasting system and the structure of the computer net work.

Abstract:In this paper, the physical features of a severe convective heavy rain, which occurs during the Meiyu period in the reaches of the Changjiang River and is difficult to forecast, are studied by the control analysis method. In such a severe convective heavy rain oecuring in the warm section far from the front, the upper divergence and lower convergence seldom move synchronously. When the upper divergence moving eastward along the edge of the subtropical high overlaps the lower quasi-static convergence, there occurs a heavy rainfall, and when the upper divergence moves away from the convergence, the heavy rain stops. Thus, attention should be paid to the divergence field above 200 hPa as well as the conditions of the lower convergence so that good results can be achieved for forecasting such heavy rain.

Abstract:In this study, several lateral boundary conditions, including fixed, radiational and time-dependent lateral boundary conditions, are tested. It is found that the results are greatly improved when the time-dependent lateral boundary conditions are used. Therefore, once the machine conditions permit, it is desirable to adopt a scheme for the better treatment of the lateral boundary conditions or set about developing a nested grid model with coarse and fine meshes.

Abstract:The mesoscale heavy rain vortex is mainly located on the 800-700 hPa isobaric surface with its center between the southwest and northeast jets and an anticyclonic circulation in both its lower part and the upper troposphere. The center of the vortex is a descending area and its rim an ascending band. It is found that the heavy rain vortex center has an obvious tendency to move toward the unstable area of the disturbanc field.

Abstract:A two-way grid model internested by coarse-fine mesh is designed. As the model is self-internested, it densifies the grid, much Improving the quality of forecasting without having to do many calculations. Results show that operation is stable in the 24-hr simulation process and there is no incoordination between the boundary values at the nested grid. The new model proves to be an improvement on the original one in heavy rain forecasting.

Abstract:When the upper divergence moves eastward and overlaps the lower convergence, a strong convective activity will occur throughout the troposphere, with a maximum ascending velocity at the mid-level of the troposphere, wherein severe heavy rain develops. It is seen that the upper forcing plays a more important role than the lower-level conditions in the occurrence of heavy rain.

Abstract:The meso-β scale convective cloud cluster evolution and mesoscale disturbance in the heavy rain process are discussed by intensified display of infrared cloud pictures and 1-hr rainfall amount, diagnostic analysis of some major physical quantities and the band-pass filtering wave method.

Abstract:From the three-dimensional advection equation, the related expressions for the coordination between horizontal and vertical resolutions of a model are derived. Thereafter, case calculations are performed, obtaining some useful results.

Abstract:By using mainly GMS pictures, together with radar echo and ground data, this paper analyzes the relation between the development of heavy rain cloud clusters in 0-6 hrs before 50 heavy rain occurrences in the regions of the Three-Gorges and Jingjiang River, and the large-scale environmental cloud field. Established according to different trigger mechanisms are five types of concept models, cold front, stationary front, convergence north of the front, mesoscale occlusion and arcus line related to typhoon, upon which criteria are provided for nowcasting heavy rain. Satisfactory effects have been achieved in the operational tests in the period of June-August, 1989.

Abstract:Using Wuhan WSR-81S digitized radar data and hourly ground temperature, pressure, humidity, wind and rainfall data, a detailed mesoscale analysis is conducted of the non-regional heavy rain that occurred in the Jianghan plain on August 18, 1987, with an acquirement of initial knowledge of its formation and development.

Abstract:Having analyzed 850 raindrop size data from 1987 to 1989, we obtain the following regressional formulas of radar reflectivity factor (Z) and precipitation intensity (R):(1) Wuhan Area:precipitation from stratiform clouds:Z=200.7R^1.259precipitation from cumuliform clouds:Z=292.4R^1.265(2) Yichang Area:precipitation from stratiform clouds:Z=259.3R^1.407precipitation from cumuliform clouds:Z=361.9R^1.477

Abstract:In this paper, by using satellite cloud pictures for 22 episodes of heavy rain and severe convective weather over the middle reaches of the Changjiang River since 1980, the formation of clond clusters and evolution of cloud systems are analyzed, and three types of heavy rain cloud clusters summarized. It is found that most of the cloud clusters affecting the AB area originate from the cumulus clouds in the southerly flow in the southwest of the area. Accordingly, a useful procedure for monitoring and forecasting, the heavy rain in the area is preliminarily established.

Abstract:We derived a mesoscale concept model for heavy rain occurring over the middle reaches of the Changjiang River from the analysis of more than 10 heavy rain episodes, obtaining certain criteria for mesoscale heavy rain forecasting from the aerological and surface physical fields. From June to August, 1989 we carried out a fore-experiment and with good results.

Abstract:By using the continuously moving image data obtained every 10 minutes by the Wuhan digitized weather radar system, the radar echo characteristics and the genesis, development and movement regularities of several main types of torrential rain and severe convective weather in the detecting area are described and analyzed. In addition, the factors relative to noweasting are examined.

Abstract:Analyses of the WSR-81S digital data for 5 precipitation processes and the rainfall data from 16 auto-raingauges indicate that the rainfall amount in the joint detecting areas by weather radar and the auto-raingauge network is more precise than is detected by radar or the conventional raingauge network alone. Some other advantages of the joint detection project are also discussed in this paper.

Abstract:The basic principle and realization technique of the variational method used in calibrating weather radar regional rainfall measurements are introduced. Based on the layered color image data obtained by the digitized weather radar at Wuhan, the regional rainfall occurring in 5 rainstorms in 1987 and 1988 are calculated with this method. Thereafter, preliminary analysis and discussion are made of the calculation results.

Abstract:Good temporal and spacial resolutions and operational reliability Should be taken into consideration in the digitized radar system for monitoring meso- and micro-scale weather.In this paper, a novel idea is suggested that a new auxiliary processing and controliing system should be added to the WSR-8IS radar. Its unusual hardware structure and software function make the above properties possible.

Abstract:Based on the findings from our studies in the past four years, examinations are made of the operational experiment scheme started in 1990 for monitoring and forecasting severe convective weather over the middle reaches of the Changjiang River.

Abstract:Described herein are the real-time meteorological data bank system, the multi-task program design adopted in the system and the communications, in the Wuhan Regional Meteorological Center. Besides, a brief account is given to the multi-index and half-search techniques which are adopted in the data structure design to solve the problem of relatively small memory capability and to quicken the searching speed of the real-time data in the bank.

Abstract:The dissemination of real-time data and forecasting products is an important link in modern weather nowcasting system. By means of the Wuhan digitized weather radar system, a design scheme of the remote microcomputer terminal grid is proposed for the weather nowcasting service system. on the basis of the experimental studies, the main techniques and requirements in the dissemination are also suggested.

Abstract:There are more and more kinds of operational image display stations used in weather forecasting, of which the IBM pC/(286,386) small-sized system is extremely useful for short-range forecasting. Based on the successful experimental operation of the Wuhan small-sized synthetic display system during the flood season of 1989, the technical requirements for operational application, the approach to techniques and its potentiality are proposed.

Abstract:The technique of synthetic processing and overlapping of radar and satellite imagery is quite recent. In this paper, the coordinate assimilation of the digital weather radar network mosaic and overlapping with H satellite imagery, and its implementation in the Wuhan Regional Center are described. The coordinate distortion of the two base maps from the projection is also analyzed and discussed.

Abstract:Based on the pre-experimental operation results of the nowcasting subsystem in the Wuhan Central Laboratory and comparing the operational conditions of the same type at home and abroad, preliminary investigations are made of the operational stability of the system. Thereafter, several factors affecting the operational stability and the knowledge of them are discussed.

Abstract:For the purpose of monitoring meso-scale short-range disastrous weather, an automatic weather system is designed, which consists of an automatic weather station,a relay station and a central station. Theoperational principle and structure of the system is introduced in detail, with emphasis on the sensor to weather elements,and the hardware and software structures of the system.

Abstract:In this paper, the type selection, working principle, communation regulation design and function operation of the forward communication machine in an automatic weather station system are described. In order to improve the long-term operational reliability, the dual cold machine configuration and aatotiming job exchange are adopted in the system, and the CMOS technique is employed in the design of the whole system so that the power consumption can be reduced and the interferenceresistant ability raised.

Abstract:A brief account is given to an expert system for the very shortrange heavy rain forecasting, including its stracture, functions, properties, knowledge presentation, inference performance and operation.

Abstract:A nowcasting system for heavy rain is designed mainly based on the digitized radar data. By using objective extrapolation for determining the future location of the echo system and using the concept model along with the forecaster’s experience for revising its future intensity quasi-objective forecasting results are obtained.

Abstract:An operational system, which can be nsed to predict objectively the regional and point precipitation in four hours, has been established by using digital infrared satellite data and daily meteorological messages. The system can work on the IBM-pC computer, satisfying the requirement for real time forecasting. It is proved from the operational tests last year that the system is quite effective in forecasting.

Abstract:In this study, a method is proposed, using GMS-3 satellite digital data every three hours, for analyzing the relation between cloud grey degree and rainfall. Several parameters are thusobtained, from which rainfall intensity and locality in the "A, B" areas have been satisfactorily estimated in three hours.

Abstract:In this paper, the limited-area NW_P model from the National Meteorological Center, Beijing, and the limited-area fine-mesh NWP model from the Wuhan Research Institute of Heavy Rain are studied and analyzed when they are used for very short-range rainstorm forecasting. Some problems in the application of NW_P products are also pointed out.

Abstract:In this paper, techniques of determining the gains of the large antenna in the WSR-81S are briefed.Control analyses are made of the testing results and errors.

Abstract:In recent Years, digital technique has been used in the data processing of weather radar images and meteorological satellite cloud pictures, and real-time data banks have been set up successively in regional meteorological offices. By utilizing available facilities, how to realize the rapid and accurate transmission of data and to share the real-time data resource are ugent problems in meteorological communication to be solved at present.We have achieved midium/high speed data transmission from December 1988 by the special meteorological telegraph-telephone communication lines in the provence range, firstly solving the problems in nationwide meteorological communication.