Introduction

1. Development Strategies and Technical Measures of Short-term Forecast Operational Platform System in NingixaHU Wen-dong1,2 ZHAO Guang-ping2 DING Jian-jun1,2(1Key Laboratory of Meteorological Disaster Preventing and Reducing in Ningxia, 2Ningxia Meteorological Observatory, Yinchuan China, 750002)

2. Introduction • China Meteorological administration initiated the plan to setup a 126-Doppler- radar network for the first stage in 1998, in order to improve the monitoring and forecasting standard [1]. The first Doppler radar in Ningxia was setup in Yinchuan city as the key to the project meso-scale disaster weather warning system, and the monitoring and warning level was elevated. In recent years, Ningxia meteorological bureau has completed many achievements both in hardware and software. For the purpose of turning hardware advance into social-economic benefit and raising the ability of operational forecast, and integrating of operational system with other equipments and products had been completed, and building up a new type forecast body, the short term forecast platform system was developed • Many kinds of data with a very huge amount were involved in this platform system and the temporal need for operational work is very strict. The strategies must be paid extra attention and special measures must be taken.

3. 1.Technical base of short term forecast • Ningxia meteorological bureau bought a SGI ORIGIN 300 computer with the peak speed of 12 billion/s in 2002. On this computer the local meso-scale numerical weather predict (NWP) was set up based on MM5V3. After redeveloping on local NWP, a system of more than 170 kinds of element with a horizontal resolution of 20km and temporal resolution of 1h was completed, and the refined forecast system was primarily established on June 7 2003 to provide public forecast products each 6h routinely for all of the counties in Ningxia[2,3]. With 21 auto meteorological stations, Doppler radar, meteorological satellite meso-scope utilizing station and delivered NWP products, the condition to develop a short term forecast platform system based on the practical environment is mature.

4. 2.Analysis on characteristics and requirement of short term forecast system • 2.1 Consideration to build the short term forecast system • Bearn[4] pointed out that radar is the key instrument to short term forecast. The forecasters in the US think Doppler radar is the most important technology introduction in the half of the last century [5], Doppler radar products should be the most concernment of the short term forecast, especially for the monitoring and warning of disaster weathers. • The route to realize the short term forecast system is, to integrate the Doppler radar data, NWP data, refined short range weather forecast data, satellite data, auto-meteorological station data in high spatial and temporal resolution and the conventional meteorological data, develop the different forecast models by the means of meso-scale synoptic, diagnosis, radar and satellite weather analysis. In the operational network environment of Ningxia meteorological bureau, taking windows as computer operational system, develop a convenient and efficient operational platform system and make the issue.

5. 2.2 Requirement characteristics of short term forecast system • It is obvious that the short-term system must be supported by multi-type meteorological data, and under nowadays situation, the available data are abundant. In less than 20 or even several minutes the Doppler radar can finish a volume scan and provide data as much as 20mb or more. Considering the huge amount data of the satellite, auto meteorological stations, NWP products, the data are colossal in total. In the limited time to make forecast products, it is absolutely necessary to collect, transmit and process the data, to form the original version of forecast, to scientifically organize weather background and similar events for the forecasters, to provide them with powerful facility to revise the forecast for the forecasters. • So the first should be remarked is the huge amount and multi-type of the data for the short term forecast system.

6. The task of top priority or short term forecast system is, to monitor hazardous weather and issue the dangerous warning dynamically in high frequency and to revise and make out the detail about suddenly occurred weather disaster according to the last information. The weather disaster always caused by meso-scale system, and its lifespan is quite short. In order to monitor and forecast effectively, all the work relevant to the short term forecast must be completed within the life expanse or equivalent, or it is out of date. • The 2nd characteristic of short term forecast system is the stringency of time. • The short term forecast system depends on different data of type. Because of the fault of detecting equipment, communication systems, it is almost impossible both to keep the integrity of data and to expect them arrive in time. And it is crucial to ensure the normal ability to carry out the routine for the operational system.

7. Here comes the 3rd characteristic of short-term forecast system, the stability of system even without entire information • China meteorology administration is developing swiftly, the new equipment, new data are being implemented rapidly, new systems and new approaches are being setup and gotten perfect swiftly. The short term forecast system connects to many instruments, multivariate data, and it is affected greatly by all of them. It is very important to guarantee the lifespan of the system with thoughtful strategies. • The 4th and last characteristic of short-term forecast system we think is expandability and compatibility.

8. 3. Development strategies and technical approach • Just as Browning[6] indicated, it should be planed as whole to design the system aimed at the three taches of data acquirement including detection and communication, comprehensive processing or analysis and forecast and products delivering according to the features of meso-scale system under the circumstance of best ratio of performance to price.

9. 3.1 Reducing the expense of time • Because of the strictly limited working time cycle of short term forecast system, the time expense must be well calculated. • In allusion to the peculiarity of multi-type of information, huge amount of data, and strictly demanded of time, the principle strategy on the point of detection and communication is, many distributed computers process simultaneously, and the data were collected by high speed local network, and it is accomplished by comprehensively organization. Most of preprocess were carried out in the same time by different computers located in different position, and the data were sent to operational network, the efficiency to prepare the data for the system is guaranteed. As the most important information, the Doppler radar data were ensured by a specific server. The satellite data are colossal also but the region to forecast is limited. By trimming out the unnecessary data, the amount decreased greatly. There are many reports of auto meteorological stations, in order to cut down the spending of opening and closing file operation, and provide a good condition for quality control; the reports of different stations in the same time were merged into one file.

10. 3.2 Efficiency of calling the data • The amount of data to be called during analyzing is rather big; it is of great importance to make sure that the data calling is with high efficiency. This system provided several manners to display the NWP and observation as here below concerning the different favorites of forecast work: geographic distribution of meteorological observation, temporal series change of observation, grid field such as conventional element, energy, stabilities. Measures were taken to achieve the goal of convenience: • 1) Screen was set to display window and control window, the change of windows and overlaying caused by item choosing and displaying was avoided, the process of calling data is much more simple.

11. 2) Multi-layer trees were applied to make sure the client could get the wanted data according to the sort, level and forecast time. The order to choose is consistent with the habit of forecaster and it is very easy to learn and to use. • 3) As for calling the grid field, the MICAPS was employed because the forecasters are familiar with it. A specific program was developed for the geographic and temporal distribution of observation. It is not only attained the efficiency but the higher quality also comparing with the MICAPS.

12. 3.3 Stability • For the general exuberance of system, the processes that would cause failure such as opening file, changing directory, being divided by zero etc. were checked in advance to avoid the problem. If the test fails the error process and adjust flow will be started up, and crash of system should be turned away. • In the same way, the uncompleted information was countered and settled, according to the actual situation turned to different disposal flow to make sure the stability.

13. 3.4 Expandability and compatibility • Considering the expandability and compatibility, the main functions in the system were designed as relative independent modules, and they were assembled by main menu program call and, the running control was realized. By adding the independent modules into menu the function of system was enhanced. The configure files were employed at both the main program and the module level, and it is very flexible. The file and directory setting are open to the client and easy to change with the development of operational work. All items in configure were noted with clear text for better understanding.

14. 3.5 System detection • The short term forecast system is relevant to many hardware and software systems, the connection is quite complex, it is significant to monitor all important parts and the environment. The dynamic monitoring on SGI computer, local network and computer environment were conducted by developed software. The running step, start time, processed level etc. of complex tasks such as local meso-scale model, derived element calculation were recorded. The dynamic monitoring and real-time feedback mechanism was setup at any time. • The network is one of the keys to the system; the local network status was investigated also to ensure the information communication. For the computer the forecast system was built in, the occupied percentage of CPU, memory, thread, file system, user and system resources etc. can be checked.

15. 3.6 Two flows • Ningxia located in Northwestern part of China with a continental climate. There are sudden occurred server convections caused by meso-scale weather system, and in winter the weather is stable relatively. Based on the local climate specialty, two flows were designed to meet the different needs in summer with lot of disasters event and in winter, not too much. The efficiency is improved further more. • 3.7 Convenient method to make forecast products • The combination of text and graph was utilized to make the forecast. As for the precipitation, the most important element, the graphic background of precipitation was generated by using satellite model, radar model and NWP products. The forecaster can revise with mouse in the precipitation picture according to his or her experiment and relevant information. It is very simple to modify the area and amount of rain by drawing picture, and the result can be converted into text automatically. In the products-making interface, other element can be made by using meteorological dictionary and graph easily.

16. 4. Brief summary • Along with the development of meteorological hardware and software in Ningxia, the condition to setup the short term forecast system is well provided. • The short term forecast system has its own particularity. The specific requirement of the short term forecast system was analyzed in the detecting manner, information characteristics, and time request. The strategies were discussed and the concrete measures were adopted to develop the operational system in Ningxia.

17. Reference • 1．XU Xiao-feng，construction and application of new generation of Doppler radar network of China [J]，China engineering science, (in Chinese)，2003，5（6）：7-14. • 2. HU Wen-dong, DING Jian-jun, CHEN Xiao-guang, et al.An Operational Display and Assessment System of Ningxia Refined Weather Forecast Products[J]，meteorological science and technology accepted，(in Chinese), 2004， • 2．LIU Jian-jun CHEN Xiao-guang, DING Jian-jun, et al. New 3eneration numeric weather forecast system in Ningxia [J]，meteorology accepted, (in Chinese)，2004， • 4．Bearn D.W. A. E. MacDonald, Designing a Very Short-range Forecasting, Nowcasting, Academic Press, London, 1982 • 5．Robert J. Serafin, James W. Wilson, operational Weather Radar in America: Progress and Opportunity, Bulletin of the American Meteorological Society, 2000,3 • 6．Browning K. A. System Design, Nowcasting, Academic Press, London, 1982