Vol.17, NO.5, 2006

  Previous Issue | Next Issue 
Display Method:
The Westward, Northward Advance of the Subtropical High over the West Pacific in Summer
Tao Shiyan, Wei Jie
2006, 17(5): 513-525.
[FullText HTML] (1373) [PDF 2061KB](2687)
Abstract:
The subtropical high over the West Pacific in summer is one of the most important atmospheric circulation components which influences the weather and climate of China. Using the daily averaged data derived from NCEP/NCAR reanalysis dataset and interpolated outgoing longwave radiation (OLR) data provided by the National Oceanic and Atmospheric Administration (NOAA), the variation of the position of the summer rainfall belt in eastern China is diagnosed for the selected years of 2005, 2003 and 1998. The work analyzes the nonoccurrence of Meiyu in the mid and lower reaches of the Yangtze River during the summer of 2005, the heavy flood in the Yangtze River basin during the summer of 1998, as well as the prolonged heat wave south of the Yangtze River during the second half of July in 2003. Particular attention is devoted to the study on the correlation of these abnormal weather phenomena with the westward, northward advance or southward, eastward retreat of the subtropical high in the West Pacific.Evidence shows that the advance (retreat) of the subtropical high over the West Pacific in summer can modulate the positions of the heavy rainfall belt in eastern China. During the westward, northward advance (southward, eastward retreat) of the subtropical high, the heavy rainfall belt moves northward (southward). During the persistent advance of the subtropical high, a prolonged heat wave occurs in the mid and lower reaches of the Yangtze River. The process and mechanism of the westward, northward advance (southward, eastward retreat) of the subtropical high are revealed.Hoskins et al. show that the Asian Jet can act as a waveguide in the northern summer. Chang shows that the upper tropospheric waves over the mid-latitudes generally reveal the characteristics of downstream development in summer. Enomoto et al. study the relationship between the formation of the Bonin high in August and the energy propagation of stationary Rossby waves along the Asian Jet. Based on the results from previous studies, the work clearly demonstrates through the isentropic potential vorticity analyses that the advance (retreat) of the subtropical high is caused by the propagation of the stationary Rossby waves along the Asian Jet in the upper troposphere, forming a longwave ridge (trough) along the coast of China (115°—130°E); at the same time the subtropical high advances north westward (retreats southeastward). This anomalous ridge (trough) extends throughout the troposphere with the structure of the equivalent-barotropic ridge (trough). In summer when there is a persistent longwave ridge along the coast, there will be a prolonged heat wave in the mid and lower reaches of the Yangtze River.Based on the summer forecasting experiences, it is found that the medium range forecast issued by the ECMWF may better predict the westward, northward advance of the subtropical high of the West Pacific in summer.
Design and Practice of National Meteorological HPC Management and Application Network Platform
Zong Xiang, Wang Bin
2006, 17(5): 829-834.
[FullText HTML] (679) [PDF 381KB](1922)
Abstract:
National Meteorological Information Center (NMIC) of CMA operates the fastest high performance computer (HPC) system in China and the total computing capacity of NMIC also ranks best in China and keeps a leading position among meteorological information centers all over the world. With the great-leap-forward development of capability construction, the "soft ability", characterized by system and resource management, user support and quality of service, is left behind. So efforts must be made on development enhancement and construction in this area, bringing into full play the HPC resources in NMIC. Since its birth, grid technology has seen a rapid growth and been an influential direction in information technologies. Grid brings distributed and heterogeneous computer systems together, works cooperatively as a whole, and provides nontrivial quality of service, which enables the management and sharing of HPC resources. Based on the computational grid concept, a national meteorological HPC management and application network platform is put forward. The platform adopts centralized grid architecture, and consists of four levels, namely, user interface, grid management, HPC local management and HPC resources. The platform finds ideal solutions to four key aspects: globally consistent and centralized user management, resource management based on "resource accounts", meta-scheduler and comprehensive operation monitor. Utilizing existing work, with the introduction of mature grid software and open source software, the platform is preliminarily implemented. In the future, research and development efforts will continue in job scheduling policy, quality of service management and data grid, so as to build and perfect the national meteorological HPC management and application network platform and to put it into actual operation finally.
Simulation of the South China Sea Summer Monsoon Onset
Ding Yihui, Liu Yanju
2006, 17(5): 526-537.
[FullText HTML] (867) [PDF 3911KB](918)
Abstract:
Generally speaking, the South China Sea summer monsoon (SCSSM) onset marks the arrival of the East and Southeast Asian summer monsoon and the beginning of the major rainy season in these regions. Therefore, the correct simulation of SCSSM has a significant implication. General Circulation Models (GCMs) have limitations in reproducing regional details because of the relatively low spatial resolution and simple representation of physical processes. Hence many studies tends to use air-sea coupled model and regional climate model to simulate the seasonal variations and anomalies of the East Asian monsoon.As an important energy source for atmospheric motion, cumulus convection plays a key role in determining the structure of temperature and moisture in the atmosphere. With the development of numerical model, different cumulus parameterization schemes have been designed and applied in the numerical weather forecasting models and the simulations of atmospheric general circulation. Many studies show that the choices of different cumulus parameterization schemes may have significant influences on the simulations of synoptic and climate systems, therefore the choice of the cumulus parameterization scheme has been one of the important problems in the modeling research. With the high-resolution regional climate model of China National Climate Center (RegCM_NCC), four cumulus parameterization schemes (Kuo, Grell, MFS, Betts-Miller) are adopted to carry out a series of sensitivity experiments on the SCSSM onset in 1998. The results indicate that the model is very sensitive to the choice of convective parameterization schemes. It seems that the Kuo cumulus scheme simulates the process of the SCSSM onset reasonably well, which can reproduce the onset timing and dramatic changes before and after the SCSSM onset, especially the upper and lower level flow patterns. For the amount of precipitation and location of the subtropical high, there are still some biases between the simulations and the observations, including the location of the subtropical high simulated further north and east, the precipitation amount over the South China Sea too little as well as the range of precipitation too narrow. The ensemble results are obviously superior to any single cumulus parameterization scheme and the obvious improvement is mainly on the simulation of precipitation over the South China Sea.
Utilizing ARGO Data to Improve the Prediction of ENSO and Short-term Climate Prediction of Summer Rainfall in China
Zhang Renhe, Yin Yonghong, Li Qingquan, Liu Yimin, Niu Tao
2006, 17(5): 538-547.
[FullText HTML] (851) [PDF 267KB](1235)
Abstract:
The acquirement of the global ARGO data provides unprecedented ocean data for researches on the climate prediction, a tropical dynamic ocean-statistical atmospheric coupled model is set up. In the coupled model, the atmospheric part is a statistical atmospheric model constructed according to the correlation relationship between observed windstress and sea surface temperature in the tropical Pacific. The ocean part is Zebiak-Cane oceanic model in which the subsurface temperature parameterization scheme is improved based on the ARGO data. The long-term hindcasts are done using the coupled model. In order to understand the performance of the ARGO data in the improvement of the hindcasts, the results of the coupled model are compared using the unimproved and improved ocean models respectively. It is found that the application of the ARGO data in the oceanic model greatly raises the capability of the coupled model in hindcasting the sea surface temperature (SST) in the tropical Pacific. The hindcast of 6 months in advance gives the abnormal variations of the SST in the Niño3.4 region in good agreement with the observation. The El Niño and La Niña events in the hindcasting period are successfully hindcasted. The correlation of SSTs between the hindcasts and the observations is increased substantially in the whole tropical Pacific Ocean.The improvement of the short-term climate prediction of summer rainfall in China is also investigated by using the global atmosphere-ocean coupled model of the China National Climate Center (NCC) using the ARGO data in the Global Ocean Data Assimilation System of NCC (NCC-GODAS). The results of seasonal hindcasts for the summer precipitation in China for the case of the summer of 2002 and also for the summers from 1998 to 2003 are showed respectively. It is found that when the ARGO data is included in the NCC-GODAS, the distribution of the hindcasted summer precipitation in China is closer to the observation. The area of the positive correlation between the hindcasted and the observed summer precipitations is enlarged. It demonstrates that hindcasts for the summer precipitation in China with ARGO data in the NCC-GODAS is much better than those without ARGO data.
Decadal Variability of Rainfall Persistence Time and Rainbelt Shift over Eastern China in Recent 40 Years
Zhao Ping, Zhou Xiuji
2006, 17(5): 548-556.
[FullText HTML] (929) [PDF 1109KB](1960)
Abstract:
Using observations of precipitation from rain gauge stations in China for the period of 1960—1999 and the monthly European Center for Medium-Range Weather Forecast reanalysis for the period from 1958 to 2001, the variations of the beginning and ending time of the rainfall and rainbelt shift over eastern China between the cold and warm periods of globally averaged surface air temperatures are examined. The associated atmospheric circulation over East Asia is also analyzed. The results show that in recent 40 years, the relative cold period of the surface air temperature appears in the 1960s and 1970s, while the warm period appears in the 1980s and 1990s. Compared to the cold period, the annual total rainfall in the warm period is characterized by the feature of southern floods/northern droughts, namely that the annual total rainfall increases along the valley of the Yangtze River in the warm period and decreases over North China. The increase in the valley is mainly due to the increase of rainfall in summer (June to August) and March, while the decrease is attributed to the decrease from July to September. On the average, the persistent heavy rainfall over southern China (25°—30°N, 115°—120°E) begins earlier, ends later, and maintains longer in the warm period than in the cold period. Over northern China (34°—40°N, 115°—120°E), the persistent heavy rainfall begins later and maintains shorter in the warm period. Moreover, there is a significant difference in the rainbelt shift over eastern China from late spring to summer between the cold and warm periods. In the cold period, the rainbelt shift shows a pronounced feature from South China via the valley of the Yangtze River to North China. However, in the warm period, the rainbelt mainly appears along the valley, not showing a striking shift from South China to North China. The southern floods/northern droughts over eastern China are associated with anomalies of the East Asian atmospheric circulation under global warming. In the warm period, the low over the Asian continent and the high over the Sea of Okhotsk are strong during summer, accompanied by the anomalous northeasterlies from the south of the Sea of Okhotsk to mid-latitudes of East Asia, which may strengthen the activities of cold air at these latitudes. Meanwhile, the subtropical high over the western North Pacific is more northward in the warm period. Corresponding to these anomalies, the East Asia summer subtropical monsoon weakens and the Meiyu front strengthens along the valley of the Yangtze River, which makes the rainfall stay in the valley, resulting in the increase of local rainfall. Anomalous downward motions appear over northern China, resulting in the decrease of local rain.
Relationship Between Precipitation in Northeast China and the Atmospheric Circulation
Jia Liwei, Li Weijing, Chen Deliang
2006, 17(5): 557-566.
[FullText HTML] (748) [PDF 1445KB](1495)
Abstract:
Lamb-Jenkinson classification scheme is applied to obtain circulation types from the mean sea-level pressure on a daily basis. The relationship between the atmospheric circulation and the precipitation in Northeast China is explored. Eight major types (N, NW, NE, A, C, S, SW and W) which occur most frequently are analyzed to reveal their characteristics and their relationship to atmospheric circulation. Furthermore, the anomaly precipitation distributions under eight circulation types are discussed. The contributions of each major circulation type to total precipitation in Northeast China are investigated as well. The statistics relationship between the nine representative stations with a long record of precipitation and the frequencies of the circulation types are established successfully. The relationship is used to reconstruct the 54-year precipitation sequence at these nine stations.The results show that Lamb-Jenkinson classification scheme can be well applied in Northeast China. The classified types are reasonable. The precipitation distributions of eight major types match reasonably well with large-scale atmospheric patterns. Positive pressure anomaly corresponds to less rainfall, while negative pressure anomaly usually corresponds to more rainfall. The C type makes the greatest contribution to the total rainfall. On the contrary, N, NE, NW, A and W types have little contribution to the total rainfall. Reconstructed precipitation series in nine representative stations can explain the majority of precipitation change in recent years from 1951 to 2004, which further reveals the close relationship between the precipitation in Northeast China and the atmospheric circulation.
Regional Dense Fog Time Sequence with Its Annual and Decadal Variation in the Sichuan Basin
Zhou Zijiang, Zhu Yanjun, Yao Zhiguo, Ju Xiaohui
2006, 17(5): 567-573.
[FullText HTML] (735) [PDF 565KB](1314)
Abstract:
According to the definition in the Surface Meteorological Observation Manual, dense fog is a kind of disastrous weather phenomenon that the visibility is less than 500 meters caused by abundant tiny water drops floating in the low atmosphere layer. Since the 1980s, the traffic has increased sharply with the developing of the national economy, and the damage caused by dense fog becomes more and more severe in China. As a result, much attention has been paid to studies on dense fog.Based on the available observation data set from 20 meteorology stations located in the Sichuan Basin where dense fog occurs frequently during 1954-2005, the time series of regional dense fog has been constructed under the criterion, during the same observation day there are 5 or more stations where dense fog emerge together, in the Sichuan Basin. Furthermore, the annual and decadal variation of this time series and possible change mechanism are discussed.Results show that most regional dense fogs occur mainly during autumn and winter (September to next February), and account for 92.8% of the annual amount. In summer, dense fog events are not prone to happening, only accout for 1.4%. So it means that the time sequence of dense fog in the Sichuan Basin spans two years, from July to June of next year. Taking the 51 years as a whole, regional dense fog has an increasing tendency with 2.96 days per decade in the Sichuan Basin. During 1954-1976, regional dense fog events are less than the average of 51 years, keeping a negative phase and 18.2 days per year, especially the 1960s is the least ten years, only 15 days per year. On the contrary, dense fogs are frequent and severe through 1980s and 1990s, keeping a positive phase. In recent years, dense fogs in the Sichuan Basin are decreasing, but the number is still more than that in the 1960s. There are significant negative correlation coefficients, not only at inter-decadal scales but also inter-annual scales, between dense fogs and visibilities of background atmosphere with no fog weather in autumn and winter. It explains that in the past 51 years the number of condensation nucleus is the decisive factor on the tendency of dense fogs in the Sichuan Basin. At the same time, the relative humidity of atmosphere is another main factor for dense fog change at inter-decadal scales despite the limit influence weaker at inter-annual scales, and the local temperature warming tendency doesn't exert obvious influence on dense fogs. In recent years, the change of condensation nucleus, relative humidity and temperature lead to the decline of regional dense fogs in the Sichuan Basin.
Status Review on Atmospheric Motion Vectors-derivation and Application
Xu Jianmin, Zhang Qisong
2006, 17(5): 574-582.
[FullText HTML] (819) [PDF 208KB](1817)
Abstract:
Atmospheric Motional Vector (AMV) derived from continuous satellite images, their derivations and applications in Numerical Weather Prediction, weather analyses and forecasting as well as the recent research development are introduced and reviewed. At present, the algorithms of AMV derivation are basically identical among different satellite data processing centers. AMV image matching is used with correlation method, while AMV height assignment is physically based on one window channel and one absorption channel. The quality of AMVs derivation depends on the entire procedure of the data processing. Therefore, it is very important to guarantee the high performance of each step in data processing. Height assignment is still a challenging issue at present. Since physical height assignment does not turn out ideal results, attentions ought to be paid to the test on geometric way. Geostationary AMV gives positive contribution in tropics and southern hemisphere in NWP. Because of the lack of various types data in the polar zones, polar AMV has positive feed back in NWP. Feed back from MODIS polar winds is quite encouraging. Overlapping display of AMVs and satellite images give forecasters a unique tool at weather analysis and forecasting. It is especially useful for diagnosis of major rain belt, subtropical ridge, severe convections and tropical cyclones.
A Review of Satellite Observed Heavy Rainfall Cloud Clusters
Fang Zongyi, Qin Danyu
2006, 17(5): 583-593.
[FullText HTML] (855) [PDF 246KB](1872)
Abstract:
Mesoscale convective systems (MCSs) which produce heavy rainfall are commonly depicted as heavy rainfall cloud clusters (HRCCs) on satellite cloud imagery. Since Maddox found the mesoscale convective complexes (MCC), which produce the bulk of the warm season rainfall over much of midwestern Unite States, the early studies mainly focus on these kinds of long-lived and large-scaled HRCCs.A brief review of HRCCs including the proper and advantaged scales of HRCCs for satellite observation, the MCC, the Meiyu frontal HRCC especially in the East Asia, and the satellite data assimilation/modeling of HRCCs are presented. Meanwhile, some prospects are discussed for future HRCCs studies.In the past decades, most HRCCs studies are synoptic and/or statistic analyses, only a few reports are on the satellite assimilation and modeling. Also the integration with the rapid developing mesoscale theories is not enough that new theories and new diagnostic methodologies are still less documented. The future HRCCs studies should be more closely combined with mesoscale theories and remote sensing reanalysis techniques to study further into the mechanism of HRCC initiation and development.In order to combine HRCCs studies with practice, not only oval-shaped MCCs but also other shape MCSs should be considered. In a word, new HRCCs classification should be adopted according to their cloud-top shapes and scales. And the general characteristics of HRCCs in China, including their life cycle, activities etc, would be gained through abroad investigation.Furthermore, up-to-date remote sensing techniques are providing a great many data, for example, the temperature/moisture profiles from AMSU/TOVS retrieval and the cloud hydrometers from TMI/TRMM retrieval. These new data should be introduced to HRCC study for concerning inner cloud dynamics, thermodynamic processes and microphysics issues.
An Overview of the Development of Weather Forecasting
Jiao Meiyan, Gong Jiandong, Zhou Bing, Zhao Shengrong
2006, 17(5): 594-601.
[FullText HTML] (715) [PDF 523KB](2104)
Abstract:
The performance of weather forecasting on the precipitation and typhoon movement in recent decades is analyzed. The results show that the forecasting skills have been obviously improved. In order to illustrate these kinds of achievements, the recent progress on operational numerical weather prediction models with the methodologies used in weather analysis and forecasting are discussed. The improvement of the forecasting skills mainly relies on the progress of the numerical predication model. The updated global spectral model with new cloud physics and high resolution is proved to be with good perform ance in anomaly correlation coefficient at 500 hPa over the Northern Hemisphere and higher scores in precipitation output. Satellite data assimilation is proved to be much efficient in model skills' improvement. Moreover, the synoptic analysis is still playing an important role in the routine weather forecasting based on the scientific understanding of weather related synoptic systems and the circulation patterns. The synoptic concept models on macro-scale weather systems and heavy rainfall related weather systems are derived from rainband movement analyses and torrential rain researches. The dynamic diagnosis and prognosis are coming to be important means in severe weather forecasting. An ingredient method is developed and used as a routine technique in heavy rainfall forecasting and convective weather forecasting. The statistic interpretation of model outputs can efficiently improve the routinely direct weather elements forecasting output. It is also a technical way to realize the high temporal and spatial resolution forecasting for temperatures and precipitations.
Progress of Chinese Numerical Prediction in the Early New Century
Xue Jishan
2006, 17(5): 602-610.
[FullText HTML] (265) [PDF 262KB](2560)
Abstract:

The main achievements of the national key-research project "Innovative Researches on Chinese Numerical Weather Prediction System", which is conducted in 2001—2005 co-sponsored by Chinese Ministry of Science and Technology and China Meteorological Administration are reviewed. Aiming at the development of Chinese next generation numerical weather prediction (NWP) system which will be able to improve the NWP benefited from the availabilities of more powerful computer facilities and observational data with higher temporal and spatial resolutions, the project focuses on four main issues. They are the development of advanced data assimilation system, the development of unified model dynamic core suitable to different scales, optimization of model physics and parallel computing of NWP model in high performance computer environment. It is expected that the applications of advanced technologies in the new NWP system will result in better performance and higher flexibility for the further upgrading of the system along with the further improvement of computer resources and data availability in the near future.As the main results of this project, a new Global and Regional Assimilation and Prediction System (GRAPES in short) is developed. The main components of the system are the data assimilation system GRAPES-3Dvar, the global NWP model GRAPES-global and the regional NWP model GRAPES-Meso. GRAPES-3DVar is a three dimensional variational assimilation system suitable to both regional and global domains with the capability of assimilating unconventional remote sensing data, such as the radiation data from meteorological satellites. Following GRAPES-3DVar, a four dimensional variational data assimilation system (GRAPES-4DVar) is also developed, GRAPES-Global and GRAPES-Meso are based on the same unified dynamic core with hydrostatic or non-hydrostatic options. A package of model physics plug-compatible with the above model dynamic core is developed. In order to exploit the growing computer resources, parallel computing is one of the main issues in the research and the GRAPES software architecture is organized as a three-level hierarchy to make the system easily transplanted to different computers.The preliminary results of real time pre-operation experiments in a period longer than one year are presented and analyzed briefly too. It shows that the performance of GRAPES is encouraging, but the further improvement is still a critical task to meet the needs of high quality forecasts of severe weather events in China.
Development of Lightning Detection Technique with Application of Lightning Data
Zhang Yijun, Meng Qing, Ma Ming, Dong Wansheng, Lü Weitao
2006, 17(5): 611-620.
[FullText HTML] (850) [PDF 672KB](2262)
Abstract:
The developments of lightning detection techniques and methods are summarized. The applications of lightning data to the lightning warning, protection and their monitoring in severe weather are expounded. The techniques and methods of lightning detection network construction in China are also discussed. The approaches of lightning warning by using the lightning data are suggested.The lightning discharges occur in the strong convection thunderstorms and produce large currents, high voltage and strong electromagnetism radiation. So, the lightning discharges can cause personnel injuries, casualties and the property losses. The development of the lightning detection technique is very important to the lightning research and the development of lightning protection techniques. The lightning detection technique has been developing rapidly with the development of science and technology. Some means are provided for lightning monitoring and warning. It is very significant for the mitigation of lightning disasters. Meanwhile, the thunderstorms are the main sources of the lightning discharge occurrences. The monitoring of the lightning discharge may help indicate the occurrences of the severe weather such as hailstorms and rainstorms in some extent. The relationships among strong thunderstorms'dynamics, microphysical processes and lightning discharge characteristics are studied by using the lightning detection data combined with the radar and weather observations. The characteristics of the severe weather and the lightning discharge may be revealed. The methods and techniques of the severe weather warning such as the hailstorm, rainstorm may be developed by using the monitoring information of the lightning discharges. It will provide the new methods and techniques for the monitoring and forecasting of the severe weather and the foundation of improving the forecast level of the severe weather.
Meteorological Information Sharing Service Platform and Its Key Technologies
Li Jiming, Shen Wenhai, Wang Guofu
2006, 17(5): 621-628.
[FullText HTML] (825) [PDF 188KB](2284)
Abstract:
Meteorological sharing service system platform is a functional intensive system. Its function mainly concentrates on the "share of the information", and provides the convenient and quick sharing service on the meteorological information for all kinds of the users in various fields and of various levels. The intensivism of the system means the intensive administration of systematic data on meteorology of different origins and characteristics by using unified data standard and criterion. It also means to have the highly efficient collocation under the unified top layer devise by using the essential information establishment efficiently, such as the computers.Meteorological sharing service system platform has characteristics of the structure with system of different levels on the aspects of layout, functional logic and the storage administration, etc. The key technologies of the sharing platform of the meteorology include metadata, data grid, mass storage and the data mining. Among the above four techniques, metadata technique is the basic technique of the information administration, discovery and exchange. Mass storage is the supportive technique which efficiently organizes and fully makes use of computer and storage equipment. Data grid technique organically integrates the metadata and the mass storage into one unified frame. Data mining technique is a kind of practical technique which provides the users with the relevant and valuable information based on the mass data. At the same time, the requirement of setting up the database around the subject that it puts forward depends on the practical performance of the former three techniques.Meteorological sharing service system platform has two characteristics. One is to provide the various users with the usage of the information sharing resources. The other is to integrate the mass information sources, diverse information resources and separate information resources. The comprehensive usage of the metadata, mass storage and the data mining by the framework of the data grid is the major current of the technical development in establishing the sharing platform. The national meteorological data storage system and the meteorological scientific data sharing system which are now under development, provide an available attempt for the establishment of the sharing platform of meteorology information on the aspects of classified storage administration of the mass information and the integration of the distributing sharing node based on the metadata.
Uncertainty Analysis of Various Sensors Calibration Results for AWS
Zhu Lekun, Zheng Lichun
2006, 17(5): 635-642.
[FullText HTML] (643) [PDF 168KB](2127)
Abstract:
All measuring results contain errors. When using high accurate instruments, the measuring error is small; otherwise, the measuring error is big. If any measuring instrument doesn't pass the calibration or verification, its measuring value doesn't have a relation to trace the origins, so the measuring value is not trustworthy.AWS is composed of various meteorological sensors (air pressure, air temperature, ground temperature, air humidity, wind direction, wind speed, precipitation and so on), data-collecting, data-processing, data-storage and data-display, etc. It is the same as other ordinary meteorological instruments that as time goes on the measuring errors of various meteorological sensors and data-loggers will drift. In order to guarantee the accuracy, the reliability, the comparability on the measuring value, using the same standard meteorological instruments and relative calibration equipment in accordance with verification regulation or calibration specification and to carry out the periodical verification and calibration of various meteorological sensors and the data-collecting of AWS are very important. By means of the analysis on the calibration results' uncertainty, it is an importance stage to examine the reliability of the calibration or verification results.How to carry out the evaluation of the uncertainties of the verification results is the technique problem which usually occurs when setting up a standard and replying to the check. Because the instrument structure principle and the using environment conditions are different, the quantity of type B standard uncertainty is different. According to JJF1059-1999 "evaluation and expression of uncertainty in measurement", the method of the evaluation for type A standard uncertainty, the evaluation of synthesize standard uncertainty and the evaluation of expand uncertainty are the same. The evaluation of type B standard uncertainty is different. It must be noticed that, when carrying out the evaluation of the uncertainties in the measurement, it is not repeated and not left out. Otherwise, it will bring nonscientific or unjust judgment for the evaluation and expression of the uncertainties of the verification or calibration results.According to verification regulation of AWS, evaluation and expression of uncertainty in measurement (JJF1059-1999), the simplification evaluation of uncertainty in measurement and the verification or calibration data, the uncertainty of measuring results of different meteorological sensors will be analyzed in details, it has important instructional significance to the evaluation of the credibility of other type AWS and normal meteorological instruments verification result.
Discussions on Some Weather Modification Issues
Mao Jietai, Zheng Guoguang
2006, 17(5): 643-646.
[FullText HTML] (806) [PDF 114KB](1832)
Abstract:
Natural precipitation process can be divided into two stages, i.e., cloud formation stage and precipitation formation stage. Although weather modification can affect the precipitation formation stage, the key factors dominating rainfall are the lifting movement which induces cloud formation and the water vapor content in the lifting air mass. Choice on the cloud seeding location and time in weather modification depends on if the operation can benefit the lifting movement. Thus, as measurements of macro- and micro-physics conditions are strengthened, measurements on the lifting movement and the water vapor in the lifting air mass should be greatly strengthened as well. At the same time, numerical simulation research should consider dynamic fields and water vapor fields, which control the development of the rainfall system.
Journal Online
Contact

© 2020 Journal of Applied Meteorological Science   京ICP备15006967号-1

Supported by Beijing Renhe Information Technology Co. Ltd