Volume 44,Issue 2,2016 Table of Contents
2016, 44(2):171-176.
Abstract:
NetCDF orients data array with features of self description, high reading and writing efficiency and high availability， it is widely used for the exchange of weather radar data or meteorological satellite data. Weather radar developed by different manufacturers has different head information and base data storage formats of different type weather radar. Therefore, a unified coding is needed for easy data exchange without loss the special information relevant to the radar and the manufacture. The data model of NetCDF as well as its application to weather radar data storage is introduced. NetCDF format encoding and decoding experiments for Xband phased array radar, Wband cloud radar, Xband weather radar, and Kaband cloud radar are carried out on Visual C++ Platform. The results show: (1) NetCDF code has advantages in the unified coding of domestic new weather radar and conventional weather radar, which can code radar data with a unified code while reserving its inherent differences.(2) NetCDF codes radar base data by coding the information of dimension, variables, attributes and data based on the structure of radar radial data, forming a selfdescriptive NC file. Users can easily achieve “automatic” decoding with the help of library functions. (3) The size difference between original radar base data and radar base data coding by NetCDF is small, and the magnitude of the difference has nothing to do with the original file size.
NetCDF orients data array with features of self description, high reading and writing efficiency and high availability， it is widely used for the exchange of weather radar data or meteorological satellite data. Weather radar developed by different manufacturers has different head information and base data storage formats of different type weather radar. Therefore, a unified coding is needed for easy data exchange without loss the special information relevant to the radar and the manufacture. The data model of NetCDF as well as its application to weather radar data storage is introduced. NetCDF format encoding and decoding experiments for Xband phased array radar, Wband cloud radar, Xband weather radar, and Kaband cloud radar are carried out on Visual C++ Platform. The results show: (1) NetCDF code has advantages in the unified coding of domestic new weather radar and conventional weather radar, which can code radar data with a unified code while reserving its inherent differences.(2) NetCDF codes radar base data by coding the information of dimension, variables, attributes and data based on the structure of radar radial data, forming a selfdescriptive NC file. Users can easily achieve “automatic” decoding with the help of library functions. (3) The size difference between original radar base data and radar base data coding by NetCDF is small, and the magnitude of the difference has nothing to do with the original file size.
2016, 44(2):177-183.
Abstract:
In order to realize the 3D display of the reflectivity factor, the radial velocity, and the spectral widthof CINRAD/CC Doppler Weather Radar, based on MATLAB, the CINRAD/CC radar raw data are extracted and analyzed, and making use of the MATLAB image processing technology, the 3D modeling and coloring of radar products are accomplished. This technique uses the pixellevel image fusion measured by threedimensional coordinates to indicate radar products of different elevation angles and different categories. Through the rotation, the 3D display of radar echo products can randomly change the angle to display the 3D structure of the radar echo quickly and easily, and the details and spatial distribution of radar echoes from different elevation angles can be observed conveniently and visually for forecasters.
In order to realize the 3D display of the reflectivity factor, the radial velocity, and the spectral widthof CINRAD/CC Doppler Weather Radar, based on MATLAB, the CINRAD/CC radar raw data are extracted and analyzed, and making use of the MATLAB image processing technology, the 3D modeling and coloring of radar products are accomplished. This technique uses the pixellevel image fusion measured by threedimensional coordinates to indicate radar products of different elevation angles and different categories. Through the rotation, the 3D display of radar echo products can randomly change the angle to display the 3D structure of the radar echo quickly and easily, and the details and spatial distribution of radar echoes from different elevation angles can be observed conveniently and visually for forecasters.
2016, 44(2):184-191.
Abstract:
In CINRAD technical support, the diagnosis and location of comprehensive faults caused by highvoltage load ignition are very complex and difficult since those faults are characterized by multispots and multicomponents involved and long time required for repair. According to the control and monitoring signal flow of transmitter high voltage, a troubleshooting procedure is developed for the radar transmitter. The standardization and practicability of the procedures are illustrated by a typical case study focused on the rapid renovation of the faults. This further proved the importance of troubleshooting procedures in CINRAD technical support.
In CINRAD technical support, the diagnosis and location of comprehensive faults caused by highvoltage load ignition are very complex and difficult since those faults are characterized by multispots and multicomponents involved and long time required for repair. According to the control and monitoring signal flow of transmitter high voltage, a troubleshooting procedure is developed for the radar transmitter. The standardization and practicability of the procedures are illustrated by a typical case study focused on the rapid renovation of the faults. This further proved the importance of troubleshooting procedures in CINRAD technical support.
2016, 44(2):192-196.
Abstract:
Combined with the CINRAD/SA radar antenna dynamic control process, structural characteristics, and symptoms, the basic processes of antenna operation are analyzed theoretically, and it is pointed out that the main reasons for radar pedestal dynamic faults occurred often in CINRAD stations are the mismatch of the actual position and dynamic rate of the antenna runs and the commands given by the RDA (Radar Data Acquisition) computer to the radar servo control system, and the mismatch of conditions and locations of the radar antenna. An indepth analysis is conducted on the working status of the key components such as the D/A converter circuit and speed compatible circuit, and the troubleshooting is conducted by means of such methods as drive chain, slip ring maintenance, and servo motor check, so as to provide references for the onsite maintenance of CINRAD/SA radar antenna failure.
Combined with the CINRAD/SA radar antenna dynamic control process, structural characteristics, and symptoms, the basic processes of antenna operation are analyzed theoretically, and it is pointed out that the main reasons for radar pedestal dynamic faults occurred often in CINRAD stations are the mismatch of the actual position and dynamic rate of the antenna runs and the commands given by the RDA (Radar Data Acquisition) computer to the radar servo control system, and the mismatch of conditions and locations of the radar antenna. An indepth analysis is conducted on the working status of the key components such as the D/A converter circuit and speed compatible circuit, and the troubleshooting is conducted by means of such methods as drive chain, slip ring maintenance, and servo motor check, so as to provide references for the onsite maintenance of CINRAD/SA radar antenna failure.
2016, 44(2):197-203.
Abstract:
In order to explore the comprehensive discrimination technology of dew and frost observation, a near surface temperature and relative humidity observation system was built in the Atmospheric Detection Test Base of CMA in 2014. Based on the nearsurface temperature and humidity observations, automatic station data, manual recordings, and video recordings of dew and frost, the comprehensive discrimination technology of dew and frost is investigated. The difference of grass temperature and nearsurface dewpoint temperature is preliminarily selected as the main distinguishing factor of dew and frost. Dew and frost occur when the difference of grass temperature and nearsurface dewpoint temperature is less than a threshold, which is related to the lowest temperature of the day. Data analysis shows that the discrimination results of dew and frost by using the comprehensive indexes are close to the actual observations, with the concordance rate being 84.5%. The nearsurface temperature and relative humidity have good indication of dew and frost.
In order to explore the comprehensive discrimination technology of dew and frost observation, a near surface temperature and relative humidity observation system was built in the Atmospheric Detection Test Base of CMA in 2014. Based on the nearsurface temperature and humidity observations, automatic station data, manual recordings, and video recordings of dew and frost, the comprehensive discrimination technology of dew and frost is investigated. The difference of grass temperature and nearsurface dewpoint temperature is preliminarily selected as the main distinguishing factor of dew and frost. Dew and frost occur when the difference of grass temperature and nearsurface dewpoint temperature is less than a threshold, which is related to the lowest temperature of the day. Data analysis shows that the discrimination results of dew and frost by using the comprehensive indexes are close to the actual observations, with the concordance rate being 84.5%. The nearsurface temperature and relative humidity have good indication of dew and frost.
Zong Chenlin
,
Zhu Haibing
,
Wang Zhicheng
,
Zhang Xiaopeng
,
Zhou Feng
,
Chen Jingwei
,
Bao Lingyan
2016, 44(2):204-210.
Abstract:
Frost and dew phenomenon observation is an important observation content of meteorological observation. The frost and dew observation uses mainly the manual method currently, which is of many drawbacks. The automatic observation principles of the capacitive frost and dew sensor are introduced, and on this basis, with focus on the test data analysis of fourmonth observation equipment from September to December 2014, the data from the device are compared with manual observation, as well as the results recognized by the standard observation device. Combining the actual situation around the installation location and the temperature and humidity information, an indepth discussion of the changing conditions of the recognition rate, failure rate, and mistake rate of reporting frost and dew and the reason that causes the recognition rate fluctuations are conducted. The experiment results show that capacitive frost and dew sensors have better recognition rate for frost and dew weather phenomena recognition in the general natural environment. On the basis of future improvement, it probably can be applied to automatic meteorological observation operationally.
Frost and dew phenomenon observation is an important observation content of meteorological observation. The frost and dew observation uses mainly the manual method currently, which is of many drawbacks. The automatic observation principles of the capacitive frost and dew sensor are introduced, and on this basis, with focus on the test data analysis of fourmonth observation equipment from September to December 2014, the data from the device are compared with manual observation, as well as the results recognized by the standard observation device. Combining the actual situation around the installation location and the temperature and humidity information, an indepth discussion of the changing conditions of the recognition rate, failure rate, and mistake rate of reporting frost and dew and the reason that causes the recognition rate fluctuations are conducted. The experiment results show that capacitive frost and dew sensors have better recognition rate for frost and dew weather phenomena recognition in the general natural environment. On the basis of future improvement, it probably can be applied to automatic meteorological observation operationally.
2016, 44(2):211-216.
Abstract:
Most automatic weather stations use a Gray code disc wind direction sensor,and in the new stations in Hebei Province, there are two types of wind direction sensors (DZZ4 and DZZ5), and the Gray code is used as the output mode of thses direction sensors, but the two models have different power supply modes, and the indications of error directions when failures are actually detected are different. According to the wind coding principles of values corresponding to the codes for Gray code disc winddirection sensors, the regularity of wind sensor error direction indication values are studied. The method can be used to realize the quick detection of direction sensor onsite maintenance, which is simple, especially for single Gray fault identification, convenient, and more suitable for stationlevel maintenance, especially for the general onsite repair in the absence of testing equipment and instruments.
Most automatic weather stations use a Gray code disc wind direction sensor,and in the new stations in Hebei Province, there are two types of wind direction sensors (DZZ4 and DZZ5), and the Gray code is used as the output mode of thses direction sensors, but the two models have different power supply modes, and the indications of error directions when failures are actually detected are different. According to the wind coding principles of values corresponding to the codes for Gray code disc winddirection sensors, the regularity of wind sensor error direction indication values are studied. The method can be used to realize the quick detection of direction sensor onsite maintenance, which is simple, especially for single Gray fault identification, convenient, and more suitable for stationlevel maintenance, especially for the general onsite repair in the absence of testing equipment and instruments.
2016, 44(2):217-222.
Abstract:
In order to solve the problems encountered in meteorological data sharing and service integration to improve the efficiency of data flow in data processing, forecast producing and product releasing, the meteorological department of Ningbo adopted such programming languages as Java, C# and Delphi to develop the meteorological information bus based on messageoriented middleware technology. In terms of data sharing, the bus can ensure the unified update of data resources. With respect to service integration, it can effectively decouple a variety of applications in the service system and improve the information exchange and the function reuse of each service platform. The features of messageoriented middleware technology and ActiveMQ are described, and the key technologies such as framework design, message standard, and the use of message queue are elaborated. The application of the technology in meteorological service in Ningbo is used to demonstrate the advantages of the meteorological information bus in the field of service integration.
In order to solve the problems encountered in meteorological data sharing and service integration to improve the efficiency of data flow in data processing, forecast producing and product releasing, the meteorological department of Ningbo adopted such programming languages as Java, C# and Delphi to develop the meteorological information bus based on messageoriented middleware technology. In terms of data sharing, the bus can ensure the unified update of data resources. With respect to service integration, it can effectively decouple a variety of applications in the service system and improve the information exchange and the function reuse of each service platform. The features of messageoriented middleware technology and ActiveMQ are described, and the key technologies such as framework design, message standard, and the use of message queue are elaborated. The application of the technology in meteorological service in Ningbo is used to demonstrate the advantages of the meteorological information bus in the field of service integration.
2016, 44(2):223-228.
Abstract:
Based on virtualization technology, the specific solution of virtualization for Taizhou Meteorological Service is put forward, which considers the room layout, the application of data center server or storage, and the requirements of new meteorological services. Blade server, FC SAN storage, and VMware were purchased, and Original server, storage and network were reconstructed. Virtual operating modes of meteorological services are built. The solution makes the data center of Taizhou Meteorological Service be versatile, scalable, and be of high availability, and achieves the unified management of resources. Moreover, the implementation and application notes of virtualization are outlined and the adaptability of operational migration and ultimately benefits are analyzed.
Based on virtualization technology, the specific solution of virtualization for Taizhou Meteorological Service is put forward, which considers the room layout, the application of data center server or storage, and the requirements of new meteorological services. Blade server, FC SAN storage, and VMware were purchased, and Original server, storage and network were reconstructed. Virtual operating modes of meteorological services are built. The solution makes the data center of Taizhou Meteorological Service be versatile, scalable, and be of high availability, and achieves the unified management of resources. Moreover, the implementation and application notes of virtualization are outlined and the adaptability of operational migration and ultimately benefits are analyzed.
2016, 44(2):229-233.
Abstract:
Downlink meteorological data is a very important data source for provincial meteorological service, which is the base of weather forecasting, climate prediction, and weather and climate research. The receiving process of downlink meteorological data is analyzed, and the construction idea of the Jiangxi downlink meteorological data monitor platform is presented. On the basis of log analysis, MVC framework, SQL Server database, HTML, and JavaScript technologies are used to design and develop the monitor platform. The realtime monitoring of the downlink meteorological data, such as download data and CMACast broadcast data, is implemented. The statistical analysis with the time scales of year, month, day, and any search time are provided in this platform. The abnormal alarming information of the background log process system can also be obtained from this platform. After the platform was put into operation, the receiving and monitor efficiency of the downlink data has been improved greatly.
Downlink meteorological data is a very important data source for provincial meteorological service, which is the base of weather forecasting, climate prediction, and weather and climate research. The receiving process of downlink meteorological data is analyzed, and the construction idea of the Jiangxi downlink meteorological data monitor platform is presented. On the basis of log analysis, MVC framework, SQL Server database, HTML, and JavaScript technologies are used to design and develop the monitor platform. The realtime monitoring of the downlink meteorological data, such as download data and CMACast broadcast data, is implemented. The statistical analysis with the time scales of year, month, day, and any search time are provided in this platform. The abnormal alarming information of the background log process system can also be obtained from this platform. After the platform was put into operation, the receiving and monitor efficiency of the downlink data has been improved greatly.
2016, 44(2):234-237.
Abstract:
The postapplication effect of meteorological instrument equipment achievements is studied. Some details of the corresponding evaluation index system, such as classifying the evaluation objects, analyzing essential characteristics, and exploring indices, are introduced. The weights of various indexes are calculated based on the analytic hierarchy process (AHP) method. The comprehensive scoring method is proposed to carry out simulation evaluation. The results show that the evaluation index system and the proposed method have the practical operability and the findings provide a reference for meteorological science and technology evaluation management.
The postapplication effect of meteorological instrument equipment achievements is studied. Some details of the corresponding evaluation index system, such as classifying the evaluation objects, analyzing essential characteristics, and exploring indices, are introduced. The weights of various indexes are calculated based on the analytic hierarchy process (AHP) method. The comprehensive scoring method is proposed to carry out simulation evaluation. The results show that the evaluation index system and the proposed method have the practical operability and the findings provide a reference for meteorological science and technology evaluation management.
2016, 44(2):238-245.
Abstract:
Using the summer DSD data observed in Nanjing by Parsivel laser precipitation particle spectrometer, the microphysical features, DSD parameters〖WTBX〗 μλ〖WTBZ〗 relationship, radar parameters 〖WTBX〗ZR〖WTBZ〗 relationship of rain intensities of four levels (light, moderate, heavy, very heavy) are analyzed. Results show that (1) the variation of the average drop diameter is small between different intensity levels, but with the increasing intensity level, the particle concentration, liquid water content, and kinetic energy contents increases; (2) Gamma drop size distribution may be greater than the number of 〖WTBX〗D〖WTBZ〗<0.625 mm〖WTBX〗 〖WTBZ〗particles at the light level and less than the number of 〖WTBX〗D<〖WTBZ〗1 mm particles at the very heavy level. Every intensity level has a good binomial function relationship between〖WTBX〗 μ 〖WTBZ〗and 〖WTBX〗λ〖WTBZ〗. The fitted curves of the lightlevel samples and all samples are close, and the fitted curves of moderate and heavy levels are close to 〖WTBX〗R〖WTBZ〗>5 mm/h samples, and the very heavy rain has higher fitted curves than 〖WTBX〗R〖WTBZ〗>5 mm/h samples. As for whole summer rain, there exists a consistent 〖WTBX〗ZR〖WTBZ〗 relationship, but the 〖WTBX〗ZR〖WTBZ〗 relationship of all samples may lead to the overestimated rain intensity for very heavy precipitation.
Using the summer DSD data observed in Nanjing by Parsivel laser precipitation particle spectrometer, the microphysical features, DSD parameters〖WTBX〗 μλ〖WTBZ〗 relationship, radar parameters 〖WTBX〗ZR〖WTBZ〗 relationship of rain intensities of four levels (light, moderate, heavy, very heavy) are analyzed. Results show that (1) the variation of the average drop diameter is small between different intensity levels, but with the increasing intensity level, the particle concentration, liquid water content, and kinetic energy contents increases; (2) Gamma drop size distribution may be greater than the number of 〖WTBX〗D〖WTBZ〗<0.625 mm〖WTBX〗 〖WTBZ〗particles at the light level and less than the number of 〖WTBX〗D<〖WTBZ〗1 mm particles at the very heavy level. Every intensity level has a good binomial function relationship between〖WTBX〗 μ 〖WTBZ〗and 〖WTBX〗λ〖WTBZ〗. The fitted curves of the lightlevel samples and all samples are close, and the fitted curves of moderate and heavy levels are close to 〖WTBX〗R〖WTBZ〗>5 mm/h samples, and the very heavy rain has higher fitted curves than 〖WTBX〗R〖WTBZ〗>5 mm/h samples. As for whole summer rain, there exists a consistent 〖WTBX〗ZR〖WTBZ〗 relationship, but the 〖WTBX〗ZR〖WTBZ〗 relationship of all samples may lead to the overestimated rain intensity for very heavy precipitation.
2016, 44(2):246-251.
Abstract:
Using the data of typhoons influencing Zhejiang from 2004 to 2013 and the corresponding winds of 9 coastal meteorological stations, the characteristics of gust ratio and its relationship with the latitude, altitude, and distance from coast to stations are analyzed. The results show that with the increasing of average wind, the gust ratio has decreasing tendency. The gust ratios of stations with less distance away from coast or less altitude are relatively larger. The relationship between typhoon parameters and gust ratio is analyzed. The ratio of the radius of grade7 wind circle to the distance of the station from typhoon center is well correlated with gust ratio. Based on the quantile regression, the probability forecast models are developed. The forecast tests show that the hit rates of 50% and 90% are obtained for most stations, and its variation is generally within a range of 3%.
Using the data of typhoons influencing Zhejiang from 2004 to 2013 and the corresponding winds of 9 coastal meteorological stations, the characteristics of gust ratio and its relationship with the latitude, altitude, and distance from coast to stations are analyzed. The results show that with the increasing of average wind, the gust ratio has decreasing tendency. The gust ratios of stations with less distance away from coast or less altitude are relatively larger. The relationship between typhoon parameters and gust ratio is analyzed. The ratio of the radius of grade7 wind circle to the distance of the station from typhoon center is well correlated with gust ratio. Based on the quantile regression, the probability forecast models are developed. The forecast tests show that the hit rates of 50% and 90% are obtained for most stations, and its variation is generally within a range of 3%.
2016, 44(2):252-258.
Abstract:
Based on the data from Xichang Doppler weather radar, the characteristics of 24 hail clouds from 2006 to 2013 in Liangshan are analyzed. The results show that all hail clouds have some common features: maximum reflectivity is above 50 dBz; echo top is higher than the height of －30 ℃ level; the height of 45 dBz echo top is higher than the height of －10 ℃ level; and the vertically integral liquid water is above 8 kg〖DK〗·m-2. The hail clouds can be distinguished according to such features as maximum reflectivity being above 50 dBz; echo top being higher than the height of －30 ℃ level; the height of 45 dBz echo top being higher than the height of －10 ℃ level, with a lead time of 4 min to 40 min for early warming. The vertically integral liquid water being over 8 kg〖DK〗·m-2 is not good to early identification of hail clouds. Comparison with shorttime heavy rainfall, the height of 45 dBz echo top being higher than the height of －10 ℃ level is useful for early identification of hail clouds.
Based on the data from Xichang Doppler weather radar, the characteristics of 24 hail clouds from 2006 to 2013 in Liangshan are analyzed. The results show that all hail clouds have some common features: maximum reflectivity is above 50 dBz; echo top is higher than the height of －30 ℃ level; the height of 45 dBz echo top is higher than the height of －10 ℃ level; and the vertically integral liquid water is above 8 kg〖DK〗·m-2. The hail clouds can be distinguished according to such features as maximum reflectivity being above 50 dBz; echo top being higher than the height of －30 ℃ level; the height of 45 dBz echo top being higher than the height of －10 ℃ level, with a lead time of 4 min to 40 min for early warming. The vertically integral liquid water being over 8 kg〖DK〗·m-2 is not good to early identification of hail clouds. Comparison with shorttime heavy rainfall, the height of 45 dBz echo top being higher than the height of －10 ℃ level is useful for early identification of hail clouds.
2016, 44(2):259-268.
Abstract:
Based on the hourly global radiation data collected at Beijing Weather Observatory and 24hour forecasting data of 14 conventional meteorological elements using the BJRUC model, three linear correction methods are used to correct the forecasted global radiation data. Seasonal differences of corrected effects using different correction schemes and sample numbers are discussed in detail. The best rolling correction schemes are investigated. Results show: (1) Influencing factors for correcting global radiation are different in 4 seasons, and primary factors such as global radiation, specific humidity and relative humidity at 2 m, low and middle cloud cover, water vapor mixing ratios, total water mixing ratios (cloud, rain, ice, snow, and graupel) are recommended to for correction of global radiation. (2) Seasonal differences of the best sample number for different correction schemes should be considered. (3) The corrected effects using the hourly rolling scheme are better than those by using other models. By means of the hourly rolling scheme, the average absolute error, mean relative error, and relative root mean are obviously reduced, and 79% of total data are improved after correction. Furthermore, absolute errors of the corrected global radiation present the typical normal distribution pattern. The scatter distribution of corrected and observed values is more concentrated, and larger positive errors are improved after correction. (4) The correction effects in spring and winter are better than those in autumn and summer. It may be caused by seasonal differences of forecasting errors of macroscopic and microscopic cloud physical parameters.
Based on the hourly global radiation data collected at Beijing Weather Observatory and 24hour forecasting data of 14 conventional meteorological elements using the BJRUC model, three linear correction methods are used to correct the forecasted global radiation data. Seasonal differences of corrected effects using different correction schemes and sample numbers are discussed in detail. The best rolling correction schemes are investigated. Results show: (1) Influencing factors for correcting global radiation are different in 4 seasons, and primary factors such as global radiation, specific humidity and relative humidity at 2 m, low and middle cloud cover, water vapor mixing ratios, total water mixing ratios (cloud, rain, ice, snow, and graupel) are recommended to for correction of global radiation. (2) Seasonal differences of the best sample number for different correction schemes should be considered. (3) The corrected effects using the hourly rolling scheme are better than those by using other models. By means of the hourly rolling scheme, the average absolute error, mean relative error, and relative root mean are obviously reduced, and 79% of total data are improved after correction. Furthermore, absolute errors of the corrected global radiation present the typical normal distribution pattern. The scatter distribution of corrected and observed values is more concentrated, and larger positive errors are improved after correction. (4) The correction effects in spring and winter are better than those in autumn and summer. It may be caused by seasonal differences of forecasting errors of macroscopic and microscopic cloud physical parameters.
2016, 44(2):269-274.
Abstract:
An analysis is made of the statistical characteristics of 20 convective indexes in 291 samples from June to August, 2011 to 2013 in Wuhan and their correlation with lightning activities. The results indicate that the correlation between some convective indexes and lightning activities is good. The equation of lightning probability potential forecast is constructed by means of multidimensional linear regression using those convective indexes for prediction with consideration of each index in close correlation with lightning activities, and passed the significance test of α = 0.05. Using the lightning data from June to August in 2014, the forecast results are verified. The results show that: Percent of Doom (POD) is 82.6%, False Alarm Rate (FAR) is 23.3%, Critical Success Index (CSI) is 63.3%. It is obvious that this method has better indicative significance and reference value for Wuhan lightning activity forecasting and warning.
An analysis is made of the statistical characteristics of 20 convective indexes in 291 samples from June to August, 2011 to 2013 in Wuhan and their correlation with lightning activities. The results indicate that the correlation between some convective indexes and lightning activities is good. The equation of lightning probability potential forecast is constructed by means of multidimensional linear regression using those convective indexes for prediction with consideration of each index in close correlation with lightning activities, and passed the significance test of α = 0.05. Using the lightning data from June to August in 2014, the forecast results are verified. The results show that: Percent of Doom (POD) is 82.6%, False Alarm Rate (FAR) is 23.3%, Critical Success Index (CSI) is 63.3%. It is obvious that this method has better indicative significance and reference value for Wuhan lightning activity forecasting and warning.
2016, 44(2):275-282.
Abstract:
Based on the routine observational data, SWAN networking charts, radar data of Changsha Station, intensive automatic weather station data and 1°×1° NCEP 6 h reanalysis data, the circulation pattern of the squall line in front of a typhoon on 18 July 2014 in Hunan and Jiangxi Province and the Doppler radar characteristics are analyzed. The results show that: the preferable vapor conditions in the lower atmosphere, the unstable thermal stratification, the high lapse rate of temperature gradient, and high CAPE provided favorable potential conditions for the development of the squall line before generation; the inverted typhoon trough was the main influential system of the squall lines, and the front and the surface convergence line triggered the squall line; the bowshaped echo, midaltitude radial convergence (MARC), highspeed value zones, gust fronts, etc. appeared during the westward and northward movement of the squall line. The squall line in front of typhoons are different from westerly ones: at the low levels the vertical wind shear is mainly dominated by wind velocity differences; the cold air invasion is not as obvious as in the middle and upper levels; there is no evident thunderstorm high at the mature stage, but distinct positive pressure variation is detected; the squall line process happened in warm and humid environmental conditions, with influx of southeast jet stream on its rear side, and its evaporation of rainfall was weaker than that of westerly squall lines. The characteristics of MARC on the velocity diagram were apparent, yet without massive differences between positive and negative velocities (15 to 27 m/s), which are the reasons why the squall line went through Hunan Province without bringing severe disasters.
Based on the routine observational data, SWAN networking charts, radar data of Changsha Station, intensive automatic weather station data and 1°×1° NCEP 6 h reanalysis data, the circulation pattern of the squall line in front of a typhoon on 18 July 2014 in Hunan and Jiangxi Province and the Doppler radar characteristics are analyzed. The results show that: the preferable vapor conditions in the lower atmosphere, the unstable thermal stratification, the high lapse rate of temperature gradient, and high CAPE provided favorable potential conditions for the development of the squall line before generation; the inverted typhoon trough was the main influential system of the squall lines, and the front and the surface convergence line triggered the squall line; the bowshaped echo, midaltitude radial convergence (MARC), highspeed value zones, gust fronts, etc. appeared during the westward and northward movement of the squall line. The squall line in front of typhoons are different from westerly ones: at the low levels the vertical wind shear is mainly dominated by wind velocity differences; the cold air invasion is not as obvious as in the middle and upper levels; there is no evident thunderstorm high at the mature stage, but distinct positive pressure variation is detected; the squall line process happened in warm and humid environmental conditions, with influx of southeast jet stream on its rear side, and its evaporation of rainfall was weaker than that of westerly squall lines. The characteristics of MARC on the velocity diagram were apparent, yet without massive differences between positive and negative velocities (15 to 27 m/s), which are the reasons why the squall line went through Hunan Province without bringing severe disasters.
2016, 44(2):283-289.
Abstract:
To investigate the pulse storm occurred at 06:00 23 July 2014 in the urban area of Chengdu, the data of Doppler radar, wind profile, automatic weather station, conventional observation, and NCEP 1°×1° reanalysis are synthesized and analyzed. It is demonstrated that the clear sky solar radiation and lowlevel water transportation provide energy and moisture conditions for convection development in Chengdu thereabout. The warm advection and urban heat island of the surface layer enhanced the uplift movement at lower levels over the Chengdu urban area. In the weak vertical wind shear area, when gust front meeting with the mesoscale hot center and convergence line on the ground, the pulse storm occurred and developed. The features of the severe storm can be found from Doppler radar echoes, such as the overhanging echo, boundary weak echo range, midaltitude radial convergence, etc.
To investigate the pulse storm occurred at 06:00 23 July 2014 in the urban area of Chengdu, the data of Doppler radar, wind profile, automatic weather station, conventional observation, and NCEP 1°×1° reanalysis are synthesized and analyzed. It is demonstrated that the clear sky solar radiation and lowlevel water transportation provide energy and moisture conditions for convection development in Chengdu thereabout. The warm advection and urban heat island of the surface layer enhanced the uplift movement at lower levels over the Chengdu urban area. In the weak vertical wind shear area, when gust front meeting with the mesoscale hot center and convergence line on the ground, the pulse storm occurred and developed. The features of the severe storm can be found from Doppler radar echoes, such as the overhanging echo, boundary weak echo range, midaltitude radial convergence, etc.
2016, 44(2):290-296.
Abstract:
A heavy rain event took place in the northeast of Chongqing from August 31 to September 2 in 2014. An analysis is made of this process by using data of conventional observations, NCEP 1°×1°, automatic station, SWAN products, and wind profile. The results show: (1) The persistent heavy rain was produced in a favorable situation. A trough at high altitudes in north of the subtropical high moved slowly due to exceptionally stable subtropical high on the southern China. Persistent largescale forcing induced by the highaltitude trough and the lowlevel shear line maintained the consequent heavy rainfall. (2) Strong southwest warm air and northeast cold air besides the lowlevel shear line intersected in the northeastern region of Chongqing, which led to obvious frontogenesis. The frontal zone was quasistationary during rainstorms. Different 〖WTBX〗θ〖WTBZ〗se in different levels were beneficial to the increasing of instability in the middle and lower troposphere in the front area. (3) Wind profiler radar displayed that the southwest LLJ significantly enhanced during the rainstorms; LLJ sustained more than 8 hours between 1 km and 3 km; and the maximum wind speed exceeded 18 m/s. Significant high divergence and low convergence existed during the rainstorms. (4) The interaction between wind and terrain increased precipitation significantly. TREC (Tracking Radar Echoes by Correlation) winds show that the southwest flow maintained to the south of the Daba Hill, and the wind direction was nearly perpendicular to the mountain strike, so that the terrain effect increased precipitation in front of the mountain, which induced the heavy rainfall along the strike of the Daba Hill.
A heavy rain event took place in the northeast of Chongqing from August 31 to September 2 in 2014. An analysis is made of this process by using data of conventional observations, NCEP 1°×1°, automatic station, SWAN products, and wind profile. The results show: (1) The persistent heavy rain was produced in a favorable situation. A trough at high altitudes in north of the subtropical high moved slowly due to exceptionally stable subtropical high on the southern China. Persistent largescale forcing induced by the highaltitude trough and the lowlevel shear line maintained the consequent heavy rainfall. (2) Strong southwest warm air and northeast cold air besides the lowlevel shear line intersected in the northeastern region of Chongqing, which led to obvious frontogenesis. The frontal zone was quasistationary during rainstorms. Different 〖WTBX〗θ〖WTBZ〗se in different levels were beneficial to the increasing of instability in the middle and lower troposphere in the front area. (3) Wind profiler radar displayed that the southwest LLJ significantly enhanced during the rainstorms; LLJ sustained more than 8 hours between 1 km and 3 km; and the maximum wind speed exceeded 18 m/s. Significant high divergence and low convergence existed during the rainstorms. (4) The interaction between wind and terrain increased precipitation significantly. TREC (Tracking Radar Echoes by Correlation) winds show that the southwest flow maintained to the south of the Daba Hill, and the wind direction was nearly perpendicular to the mountain strike, so that the terrain effect increased precipitation in front of the mountain, which induced the heavy rainfall along the strike of the Daba Hill.
2016, 44(2):297-304.
Abstract:
A continuous heavy fog event along with a thunderstorm process in Guangzhou Baiyun Airport on 12 March 2014 is investigated by using the conventional observation data and WRF model simulation. The results show that the lowlevel southerly warm and wet flow provided sufficient moisture and wind conditions for the formation of this fog process; the sufficient moisture and the longtime inversion on the near surface layer were the main causes for the durative heavy fog. The inversion and the atmospheric saturation state were destroyed by the north wind moving down along with the cold front, which was the dynamic factor of the heavy fog disperses. The spatial distribution and hourly heighttime sequence diagram of water vapor content simulated by WRF can be used as references for forecasting the formation, maintenance, and dissipation of heavy fogs. The thunderstorm occurred under the background of high trough, shear line, and surface front, which was triggered by the combined action of 850 hPa shear line and the surface front.
A continuous heavy fog event along with a thunderstorm process in Guangzhou Baiyun Airport on 12 March 2014 is investigated by using the conventional observation data and WRF model simulation. The results show that the lowlevel southerly warm and wet flow provided sufficient moisture and wind conditions for the formation of this fog process; the sufficient moisture and the longtime inversion on the near surface layer were the main causes for the durative heavy fog. The inversion and the atmospheric saturation state were destroyed by the north wind moving down along with the cold front, which was the dynamic factor of the heavy fog disperses. The spatial distribution and hourly heighttime sequence diagram of water vapor content simulated by WRF can be used as references for forecasting the formation, maintenance, and dissipation of heavy fogs. The thunderstorm occurred under the background of high trough, shear line, and surface front, which was triggered by the combined action of 850 hPa shear line and the surface front.
2016, 44(2):305-312.
Abstract:
Based on the intensive regional automatic meteorological station data, wind profiler data, routine observations, and NCEP reanalysis data, the circulation background, dynamical, and thermal conditions, especially the atmospheric stratification, are analyzed for the continuing severe convective weather during the onset period of 2014 rain season in Guangdong province. The results show that the severe convective weather appeared in the severe convergent area and updrafts in front of the maximum wind speed of a lowlevel jet, and the vertical wind shear increased rapidly before the severe convective weather happening, which has indicative significance for prediction. The mesoscale depression and ground convergence line are indicative of the convection location. Thermodynamic analyses show that the lasting warm advection by lowlevel jet along the temperature gradient from the warm area of Beibu Gulf is the fundamental cause of the maintenance of the instable stratification in Guangdong Province. Therefore, the variation of lowlevel jet and temperature field should be paid more attention for the severe convective weather during the onset period of the rain season in Guangdong Province in forecasting.
Based on the intensive regional automatic meteorological station data, wind profiler data, routine observations, and NCEP reanalysis data, the circulation background, dynamical, and thermal conditions, especially the atmospheric stratification, are analyzed for the continuing severe convective weather during the onset period of 2014 rain season in Guangdong province. The results show that the severe convective weather appeared in the severe convergent area and updrafts in front of the maximum wind speed of a lowlevel jet, and the vertical wind shear increased rapidly before the severe convective weather happening, which has indicative significance for prediction. The mesoscale depression and ground convergence line are indicative of the convection location. Thermodynamic analyses show that the lasting warm advection by lowlevel jet along the temperature gradient from the warm area of Beibu Gulf is the fundamental cause of the maintenance of the instable stratification in Guangdong Province. Therefore, the variation of lowlevel jet and temperature field should be paid more attention for the severe convective weather during the onset period of the rain season in Guangdong Province in forecasting.
2016, 44(2):313-318.
Abstract:
For a further study on the temporal characteristics of lightning current wavefront time and the demands of lightning protection engineering design, lightning risks management, and the lightning disaster prevention， the lightning current data observed by LLS (Lightning Location System) from 2007 to 2013 are used to analyze the annual, seasonal, monthly, and daily variation of lightning current wavefront time, its cumulative probability, and cumulative probability density by the mathematical statistics method. The results show that the mean wavefront time of positive lightning is 48 μs; the wavefront time of negative lightning and the total number of lightning is 36 μs; in the whole year, the shortest wavefront time for positive lightning is in July, and its monthly variation presents a Vshaped variation. On the other hand, the wavefront time for negative lightning and the total one is shorter between May and July than in any other months, and its variation appears to be an Ushaped style. The wavefront time of positive lightning changes obviously in different seasons and days, but those of negative lightning and the total one stay stable. When the wavefront time is less than or equal to 10 μs, the cumulative probabilities of wavefront time are 955%, 997%, and 996% for positive lightning, negative lightning, and the total one, respectively. The wavefront time of longer than 15 μs occupies 95% of the total lightning, and 50% for that of longer than 31 μs, only 5% for that of longer than 60 μs. When the wavefront time is 2 to 3 μs, the cumulative probability density of wavefront time is the greatest for these three kinds of lightning. The months with low temperatures have longer wavefront time, and on the contrary, the wavefront time will be shorter. The reason seems to be connected with the amplitude of lightning current, whose specific reasons need to be further investigated.
For a further study on the temporal characteristics of lightning current wavefront time and the demands of lightning protection engineering design, lightning risks management, and the lightning disaster prevention， the lightning current data observed by LLS (Lightning Location System) from 2007 to 2013 are used to analyze the annual, seasonal, monthly, and daily variation of lightning current wavefront time, its cumulative probability, and cumulative probability density by the mathematical statistics method. The results show that the mean wavefront time of positive lightning is 48 μs; the wavefront time of negative lightning and the total number of lightning is 36 μs; in the whole year, the shortest wavefront time for positive lightning is in July, and its monthly variation presents a Vshaped variation. On the other hand, the wavefront time for negative lightning and the total one is shorter between May and July than in any other months, and its variation appears to be an Ushaped style. The wavefront time of positive lightning changes obviously in different seasons and days, but those of negative lightning and the total one stay stable. When the wavefront time is less than or equal to 10 μs, the cumulative probabilities of wavefront time are 955%, 997%, and 996% for positive lightning, negative lightning, and the total one, respectively. The wavefront time of longer than 15 μs occupies 95% of the total lightning, and 50% for that of longer than 31 μs, only 5% for that of longer than 60 μs. When the wavefront time is 2 to 3 μs, the cumulative probability density of wavefront time is the greatest for these three kinds of lightning. The months with low temperatures have longer wavefront time, and on the contrary, the wavefront time will be shorter. The reason seems to be connected with the amplitude of lightning current, whose specific reasons need to be further investigated.
2016, 44(2):319-324.
Abstract:
Based on the analysis of the current situation of lightning disaster risk assessment, the demands for delicacy assessment are analyzed. Taking a bridge tower’s elevator assessment as an example, the methods of lightning disaster risk assessment of specific objects are studied. Based on the systemic analysis of lightning damage approaches, the fault tree analysis (FTA) method is introduced and used to establish models, analyze and assess the causal relation of elevator lightning damage events, so to calculate the annual probabilities of elevator lightning damage events and the most effective factors influencing the lightning damage probability and the most critical and optimal control of elevator lightning damage events.
Based on the analysis of the current situation of lightning disaster risk assessment, the demands for delicacy assessment are analyzed. Taking a bridge tower’s elevator assessment as an example, the methods of lightning disaster risk assessment of specific objects are studied. Based on the systemic analysis of lightning damage approaches, the fault tree analysis (FTA) method is introduced and used to establish models, analyze and assess the causal relation of elevator lightning damage events, so to calculate the annual probabilities of elevator lightning damage events and the most effective factors influencing the lightning damage probability and the most critical and optimal control of elevator lightning damage events.
2016, 44(2):325-330.
Abstract:
By using the daily meteorological observation data from 4 stations of Hulunbuir from 1972 to 2013, two kinds of daily comprehensive meteorological drought indexes (MCI and CI) on yearonyear basis are calculated, and the drought days, drought intensity, drought duration, and typical drought processed, as well as the coincidence degree with actual condition, are calculated and compared by means of the two kinds of drought indexes.The results show that for not considering the weight of daily precipitation, there are more jumps in CI than in MCI; in MCI, the 150day SPI (Standardized Precipitation Index) is introduced and the weights of the winter and summer precipitation are considered to avoid the overweight problem of the drought index for Hulunbeir winter and early spring droughts. In combination with actual climate and actual situation of drought disasters in Hulunbeir, the results indicate that MCI is closer to the reality and more suitable for practical applications.
By using the daily meteorological observation data from 4 stations of Hulunbuir from 1972 to 2013, two kinds of daily comprehensive meteorological drought indexes (MCI and CI) on yearonyear basis are calculated, and the drought days, drought intensity, drought duration, and typical drought processed, as well as the coincidence degree with actual condition, are calculated and compared by means of the two kinds of drought indexes.The results show that for not considering the weight of daily precipitation, there are more jumps in CI than in MCI; in MCI, the 150day SPI (Standardized Precipitation Index) is introduced and the weights of the winter and summer precipitation are considered to avoid the overweight problem of the drought index for Hulunbeir winter and early spring droughts. In combination with actual climate and actual situation of drought disasters in Hulunbeir, the results indicate that MCI is closer to the reality and more suitable for practical applications.
2016, 44(2):331-335.
Abstract:
In order to ensure the security of expressway driving in snow weather, by using the expressway traffic accident data of 2000 to 2012 over Hebei Province which from the Hebei Province Expressway Traffic Police Corps, the spatial and temporal distributions of traffic accidents in snow weather are analyzed statistically. The results show that: (1) The changes of the monthly distribution were significant, and the high incidences of traffic accidents in snow weather occurred in January, February, November and December, which account for 87.2% of the traffic accidents in snow weather in all the year. (2) There was uneven spatial distribution. The highfrequency accident spots of expressway in snow weather appeared in Expressway G4, G6, S010, etc., in Zhangjiakou region, in which the traffic accidents account for 51.1% of the total traffic accidents in snow weather. Based on the factors such as meteorological, road surface, terrain, etc., using the expert judgment method, through analyzing 29 traffic accident cases in snow weather from 2008 to 2012, the early warning indicators and the classification standards for expressway traffic in ice and snow weather in Hebei Province are proposed, and the warning accuracy rate of grade index reaches 73.9%,84.2% in G2 and G6, respectively．The indexes provide references for meteorological services and disaster prevention and mitigation.
In order to ensure the security of expressway driving in snow weather, by using the expressway traffic accident data of 2000 to 2012 over Hebei Province which from the Hebei Province Expressway Traffic Police Corps, the spatial and temporal distributions of traffic accidents in snow weather are analyzed statistically. The results show that: (1) The changes of the monthly distribution were significant, and the high incidences of traffic accidents in snow weather occurred in January, February, November and December, which account for 87.2% of the traffic accidents in snow weather in all the year. (2) There was uneven spatial distribution. The highfrequency accident spots of expressway in snow weather appeared in Expressway G4, G6, S010, etc., in Zhangjiakou region, in which the traffic accidents account for 51.1% of the total traffic accidents in snow weather. Based on the factors such as meteorological, road surface, terrain, etc., using the expert judgment method, through analyzing 29 traffic accident cases in snow weather from 2008 to 2012, the early warning indicators and the classification standards for expressway traffic in ice and snow weather in Hebei Province are proposed, and the warning accuracy rate of grade index reaches 73.9%,84.2% in G2 and G6, respectively．The indexes provide references for meteorological services and disaster prevention and mitigation.
2016, 44(2):336-340.
Abstract:
In order to improve the capability of highway traffic meteorological service in Hubei Province, and to provide the warning the products of icing on the bridge and road surface along the Wuying expressway, based on the observations of bridge and road surface temperature and conventional meteorological data from Fenghuangguan Station from 2009 to 2011 in winter, the variation regularity of conditional frequency of temperature for icing with the environmental temperature of bridge and road surface is analzed, and the warning model of risk degree for icing was established by using the logistic regression method. The results show that icing on bridge surface is more frequently than on road surface in the same environmental temperature. The environmental temperature for icing is usually 2 ℃ lower on bridge surface than on road surface. The environmental temperatures corresponding to the low, middle, and high of risk degrees of icing on bridge surface is 1 ℃,-06 ℃, and-22 ℃; and those of icing on road surface is -1 ℃,-27 ℃, and -44 ℃, respectively. The frequency of icing on bridge (road) surface varies quickly when the environmental temperature is -16 ℃ to 03 ℃ (-38 ℃ to -17 ℃), and the most sensitive temperature point to frequency change is about -06 ℃ （-27 ℃）. Therefore, the traffic risk of icing on road surface in winter can be reduced through using the warning products of icing on the bridge/road surface of the expressway.
In order to improve the capability of highway traffic meteorological service in Hubei Province, and to provide the warning the products of icing on the bridge and road surface along the Wuying expressway, based on the observations of bridge and road surface temperature and conventional meteorological data from Fenghuangguan Station from 2009 to 2011 in winter, the variation regularity of conditional frequency of temperature for icing with the environmental temperature of bridge and road surface is analzed, and the warning model of risk degree for icing was established by using the logistic regression method. The results show that icing on bridge surface is more frequently than on road surface in the same environmental temperature. The environmental temperature for icing is usually 2 ℃ lower on bridge surface than on road surface. The environmental temperatures corresponding to the low, middle, and high of risk degrees of icing on bridge surface is 1 ℃,-06 ℃, and-22 ℃; and those of icing on road surface is -1 ℃,-27 ℃, and -44 ℃, respectively. The frequency of icing on bridge (road) surface varies quickly when the environmental temperature is -16 ℃ to 03 ℃ (-38 ℃ to -17 ℃), and the most sensitive temperature point to frequency change is about -06 ℃ （-27 ℃）. Therefore, the traffic risk of icing on road surface in winter can be reduced through using the warning products of icing on the bridge/road surface of the expressway.
2016, 44(2):341-343.
Abstract:
The longterm variation of starting wind speeds of wind speed sensors is analyzed in such detection environment as sea wind, dust, and acid rain to provide the qualitative bases for the correction of meteorological data under low wind speed weather. By experiments, using the starting wind speed calibration instruments, a group of starting wind speed records about new wind speed sensor and the special working environment of wind speed sensors are obtained.The results indicate that the longterm working for in the environment of sea wind, dust, and acid rain will reduce the sensitivity of the starting wind speeds of wind speed sensors.
The longterm variation of starting wind speeds of wind speed sensors is analyzed in such detection environment as sea wind, dust, and acid rain to provide the qualitative bases for the correction of meteorological data under low wind speed weather. By experiments, using the starting wind speed calibration instruments, a group of starting wind speed records about new wind speed sensor and the special working environment of wind speed sensors are obtained.The results indicate that the longterm working for in the environment of sea wind, dust, and acid rain will reduce the sensitivity of the starting wind speeds of wind speed sensors.
2016, 44(2):344-346.
Abstract:
GB 50057-2010 and GB 50343-2012 are the main standards about the design and installation of coordinated SPDs protection for the electrical systems within structures, but there are big differences between the two standards about the SPD.An analysis is made of the definition, location, discharge current and coordination of SPDs. The results show: (1) The explanations of SPD definitions are different, but the physical meanings are consistent. (2) The requirements of SPD location are more accurate in GB 50343, and the regulations about the discharge current of SPD in GB 50057 are reasonable. (3)The calculation methods of SPD levels are different in GB 50057 and GB 50343.
GB 50057-2010 and GB 50343-2012 are the main standards about the design and installation of coordinated SPDs protection for the electrical systems within structures, but there are big differences between the two standards about the SPD.An analysis is made of the definition, location, discharge current and coordination of SPDs. The results show: (1) The explanations of SPD definitions are different, but the physical meanings are consistent. (2) The requirements of SPD location are more accurate in GB 50343, and the regulations about the discharge current of SPD in GB 50057 are reasonable. (3)The calculation methods of SPD levels are different in GB 50057 and GB 50343.
External LinksChina Meteorological AdministrationCMA Meteorological Observation CentreChinese Academy of Meteorological SciencesBeijing Meteorological ServiceNational Satellite Meteorological Center
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.