Volume 40,Issue 4,2012 Table of Contents
2012, 40(4):513-519.
Abstract:
Laboratory tests and field trials show that compared with the radar sounding system, the Chinadeveloped GPS sounding system, which uses the satellite navigation wind measurement system for wind and the derived pressure from GPS heights for pressure, has higher accuracy and precision. Its electrical performance, stability, and reliability meet the requirements of CIMO. Laboratory tests show that using the new humidity and pressure sensors in the new test conditions, the errors of accuracy are at ± 01 ℃, ± 2%, and ± 1 hPa, within the WMO requirements of conventional upper air sounding. Compared with the RS92 sounding system, the dynamic measurement performance of domestic GPS radiosondes, except for the accuracy of the relative humidity, is close to the RS92 level, especially pressure, geopotential height, wind direction and wind speed that are related with the GPS positioning, whose standard deviations of the consistency are almost equivalent to those of RS92 As for measurement accuracy, the domestic GPS radiosonde is overall better than the operational Lband sounding system.
Laboratory tests and field trials show that compared with the radar sounding system, the Chinadeveloped GPS sounding system, which uses the satellite navigation wind measurement system for wind and the derived pressure from GPS heights for pressure, has higher accuracy and precision. Its electrical performance, stability, and reliability meet the requirements of CIMO. Laboratory tests show that using the new humidity and pressure sensors in the new test conditions, the errors of accuracy are at ± 01 ℃, ± 2%, and ± 1 hPa, within the WMO requirements of conventional upper air sounding. Compared with the RS92 sounding system, the dynamic measurement performance of domestic GPS radiosondes, except for the accuracy of the relative humidity, is close to the RS92 level, especially pressure, geopotential height, wind direction and wind speed that are related with the GPS positioning, whose standard deviations of the consistency are almost equivalent to those of RS92 As for measurement accuracy, the domestic GPS radiosonde is overall better than the operational Lband sounding system.
2012, 40(4):520-524.
Abstract:
According to the actual releasing heights of 750 g meteorological balloon used at the Yangjiang station, the release heights of the 2000 g used in the comparing test organized by the CMA Meteorological Observation Center, and the release heights used during the 8th WMO intercomparison of radiosonde systems in Yangjiang, Guangdong, the influences of rainy and highhumidity weather conditions on the release heights of domestic meteorological balloons are studied. The results show that the influence of weather conditions on the releasing heights of domestic meteorological balloon is significant in rainy days or high humidity conditions. The research suggests that the rainproof and moistureproof of domestic meteorological balloons is the key to the problem of the unstable release heights for domestic meteorological balloons in some extent.
According to the actual releasing heights of 750 g meteorological balloon used at the Yangjiang station, the release heights of the 2000 g used in the comparing test organized by the CMA Meteorological Observation Center, and the release heights used during the 8th WMO intercomparison of radiosonde systems in Yangjiang, Guangdong, the influences of rainy and highhumidity weather conditions on the release heights of domestic meteorological balloons are studied. The results show that the influence of weather conditions on the releasing heights of domestic meteorological balloon is significant in rainy days or high humidity conditions. The research suggests that the rainproof and moistureproof of domestic meteorological balloons is the key to the problem of the unstable release heights for domestic meteorological balloons in some extent.
2012, 40(4):525-533.
Abstract:
The traditional EVAD technology with linear hypothesis results in relatively poorrepresentativeness mean wind field information in the calculating for upper levels with high nonlinearity. The magnitude of rootmeansquare errors of the radial velocities at equidistance rings from the 2order Fourier series fitting can indicate the level of nonlinearity. The larger the RMS, the larger the nonlinearity is. Setting the proper threshold of RMS can eliminate the relatively large nonlinear rings, which makes the rings in calculation meet the linear assumption. When the nonlinearity of winds is large, the 3 m/s threshold can avoid the bad mean wind instead of “ND” value. The mean RMS of all rings can reflect the representativeness of the mean wind field for the real wind field. The rationality of the threshold 3 m/s needs to be verified by more cases.
The traditional EVAD technology with linear hypothesis results in relatively poorrepresentativeness mean wind field information in the calculating for upper levels with high nonlinearity. The magnitude of rootmeansquare errors of the radial velocities at equidistance rings from the 2order Fourier series fitting can indicate the level of nonlinearity. The larger the RMS, the larger the nonlinearity is. Setting the proper threshold of RMS can eliminate the relatively large nonlinear rings, which makes the rings in calculation meet the linear assumption. When the nonlinearity of winds is large, the 3 m/s threshold can avoid the bad mean wind instead of “ND” value. The mean RMS of all rings can reflect the representativeness of the mean wind field for the real wind field. The rationality of the threshold 3 m/s needs to be verified by more cases.
2012, 40(4):534-541.
Abstract:
Based on the data quality control of Chinese new generation Doppler weather radar, an efficient method is proposed to recognize the clear air echoes according to the statistical results of radar data from April to September 2009 in Xuzhou, Jiangsu Province. Different recognition parameters for different radial distance (less than 25 km and between 25 and 200 km） are used to retain the clear air echoes, which can be used as nowcast reference, and remove other nonprecipitation echoes such as superrefractive ground clutters. The velocity data of the recognized nonprecipitate echo area can be employed to estimate atmospheric advection and prediction.
Based on the data quality control of Chinese new generation Doppler weather radar, an efficient method is proposed to recognize the clear air echoes according to the statistical results of radar data from April to September 2009 in Xuzhou, Jiangsu Province. Different recognition parameters for different radial distance (less than 25 km and between 25 and 200 km） are used to retain the clear air echoes, which can be used as nowcast reference, and remove other nonprecipitation echoes such as superrefractive ground clutters. The velocity data of the recognized nonprecipitate echo area can be employed to estimate atmospheric advection and prediction.
2012, 40(4):542-547.
Abstract:
Millimeter wave radar is an ideal instrument for detecting the nonprecipitation clouds and weak precipitation clouds, but it is likely to cause velocity aliasing due to its short wavelength. Velocity dealiasing is an effective means of detecting wind field information with Doppler radar. Two methods aiming at velocity aliasing with the millimeter wave radar Range Height Indicator are put forward: humanmachine interaction method and automatic method, and tests are conducted with the measured data. It is proved that both methods are satisfactory in dealing with velocity aliasing. The comparison of the results also shows that the automatic method is more efficient than the humanmachine interaction method, but for the smaller isolated area, the latter has more advantages.
Millimeter wave radar is an ideal instrument for detecting the nonprecipitation clouds and weak precipitation clouds, but it is likely to cause velocity aliasing due to its short wavelength. Velocity dealiasing is an effective means of detecting wind field information with Doppler radar. Two methods aiming at velocity aliasing with the millimeter wave radar Range Height Indicator are put forward: humanmachine interaction method and automatic method, and tests are conducted with the measured data. It is proved that both methods are satisfactory in dealing with velocity aliasing. The comparison of the results also shows that the automatic method is more efficient than the humanmachine interaction method, but for the smaller isolated area, the latter has more advantages.
2012, 40(4):548-553.
Abstract:
In the observation data from the nextgeneration weather radar adopting the mode2 precipitation observation, there are about 240 basic data and 7200 data products for one day. Because of the different formats between the file names of the basic data and data products and the file names used in data compilation, the manual compilation meets great difficulty. The key techniques of the radar data compilation and processing system and the solutions to radar data compilation are introduced systematically, in which the naming of the files can be automatically conducted in batches and by adopting the technique of the wizard task processing, the automation, batch processing, routinization, and standardization of radar case data compilation can be realized.
In the observation data from the nextgeneration weather radar adopting the mode2 precipitation observation, there are about 240 basic data and 7200 data products for one day. Because of the different formats between the file names of the basic data and data products and the file names used in data compilation, the manual compilation meets great difficulty. The key techniques of the radar data compilation and processing system and the solutions to radar data compilation are introduced systematically, in which the naming of the files can be automatically conducted in batches and by adopting the technique of the wizard task processing, the automation, batch processing, routinization, and standardization of radar case data compilation can be realized.
2012, 40(4):554-558.
Abstract:
Based on the monitoring information and sounding data of Lband radar in Yunnan Province, the LBand Radar operating status monitoring platform was developed, which includes the FTP job system, data entry system, and monitoring system. The platform structure and the technical methods are described in detail. Through analyzing the data quality of Lband sounding system, the data quality control method is proposed. The operational application of about one year shows that the platform implemented effectively the monitoring of the upper air sounding equipment and data quality, ensured the stable operation of the upper air sounding network, and improved the data quality in recent years. But the method and thresholds used in data quality control need to be improved in the process of data accumulation.
Based on the monitoring information and sounding data of Lband radar in Yunnan Province, the LBand Radar operating status monitoring platform was developed, which includes the FTP job system, data entry system, and monitoring system. The platform structure and the technical methods are described in detail. Through analyzing the data quality of Lband sounding system, the data quality control method is proposed. The operational application of about one year shows that the platform implemented effectively the monitoring of the upper air sounding equipment and data quality, ensured the stable operation of the upper air sounding network, and improved the data quality in recent years. But the method and thresholds used in data quality control need to be improved in the process of data accumulation.
8 Organization and Implementation of Capability Validation of Meteorological Metrological Laboratories
2012, 40(4):559-562.
Abstract:
The capability validation of meteorological metrological institutions is discussed from such aspects as the scheme design, reference resources, result evaluation method, big error elimination, and report making in the intercomparison activities of the like laboratories. The intercomparison activities of meteorological metrological laboratories can help establish the social status in professional metrological validation of meteorological metrological institutes, ensure the metrological standards accurate, reliable and consistent, and check the capability of meteorological metrological laboratories, as well as the staff’s technical level and ability to process data; meanwhile, through these activities, participants can found problems, accumulate experiences, identify the differences with peer institutions, and obtain references for continuous improvement and quality management.
The capability validation of meteorological metrological institutions is discussed from such aspects as the scheme design, reference resources, result evaluation method, big error elimination, and report making in the intercomparison activities of the like laboratories. The intercomparison activities of meteorological metrological laboratories can help establish the social status in professional metrological validation of meteorological metrological institutes, ensure the metrological standards accurate, reliable and consistent, and check the capability of meteorological metrological laboratories, as well as the staff’s technical level and ability to process data; meanwhile, through these activities, participants can found problems, accumulate experiences, identify the differences with peer institutions, and obtain references for continuous improvement and quality management.
2012, 40(4):563-566.
Abstract:
The postcharge regulator 3A8 is an important part of CINRAD/SA and CINRAD/SB radar, which is used to gain enough ground clutter suppression for the radar system and to regulate the PFN charge voltage within 004 percent of the desired operating point until the PFN is discharged. After the PFN charge voltage being charged to the rated value from the charging transformer, the charges stored in the PFN can be controlled by selectable discharge by sampling the PFN charge voltage. So the cycletocycle variation regulation by the post charge regulator minimizes the phase and amplitude variations in the RF output. The operating principles of Regulator 3A8 are discussed in details, and the analysis is made of the structure of the electronic circuit. Also a number of key point waveforms are discussed with the pulse sequence. Based on the maintenance experiences of the radar system, some simple and effective methods in troubleshooting and maintenance are introduced and summarized with the relevant alarm massages.
The postcharge regulator 3A8 is an important part of CINRAD/SA and CINRAD/SB radar, which is used to gain enough ground clutter suppression for the radar system and to regulate the PFN charge voltage within 004 percent of the desired operating point until the PFN is discharged. After the PFN charge voltage being charged to the rated value from the charging transformer, the charges stored in the PFN can be controlled by selectable discharge by sampling the PFN charge voltage. So the cycletocycle variation regulation by the post charge regulator minimizes the phase and amplitude variations in the RF output. The operating principles of Regulator 3A8 are discussed in details, and the analysis is made of the structure of the electronic circuit. Also a number of key point waveforms are discussed with the pulse sequence. Based on the maintenance experiences of the radar system, some simple and effective methods in troubleshooting and maintenance are introduced and summarized with the relevant alarm massages.
2012, 40(4):567-570.
Abstract:
Based on data on more than 2400 sets of national automatic weather stations monitored by the Atmospheric Observing System Operation Monitoring (ASOM) platform, the investigation of various types of spare parts from various AWS manufacturer, and the failure and maintenance information from national automatic weather stations of 22 provinces (regions) from 2007 to 2008, the fault causes, fault phenomenon and troubleshooting methods are summarized and analyzed in terms of the data collection system, sensors, power supply systems, terminal equipments, communication equipments, software, etc., thus to provide references for maintenance technicians, and lay a foundation for troubleshooting, improve logistic support capability and maintenance efficiency for AWS’s.
Based on data on more than 2400 sets of national automatic weather stations monitored by the Atmospheric Observing System Operation Monitoring (ASOM) platform, the investigation of various types of spare parts from various AWS manufacturer, and the failure and maintenance information from national automatic weather stations of 22 provinces (regions) from 2007 to 2008, the fault causes, fault phenomenon and troubleshooting methods are summarized and analyzed in terms of the data collection system, sensors, power supply systems, terminal equipments, communication equipments, software, etc., thus to provide references for maintenance technicians, and lay a foundation for troubleshooting, improve logistic support capability and maintenance efficiency for AWS’s.
2012, 40(4):571-577.
Abstract:
Sea Surface Temperature (SST) is a vital physical parameter in studying seaatmosphere exchange on the surface. To build the data sets of longtime sea surface temperature sequences, the differences between satellites, attenuation of the sensors, subjective factors of researchers and so on should be considered in establishing the retrieval model. According to the features of NOAA/AVHRR data from 1989 to 2008， a unified SST retrieval model is devised, and the 20year sequence data sets are established with the spatial resolution reached 1 km. The ship and buoy data, as well as OISST data, are used to evaluate the data sets，with the precision being around 1 ℃ (RMSE).The response of SST anomalies over the West Pacific warm pool to 1997/1998 El Nino is analyzed by using the retrieval data.
Sea Surface Temperature (SST) is a vital physical parameter in studying seaatmosphere exchange on the surface. To build the data sets of longtime sea surface temperature sequences, the differences between satellites, attenuation of the sensors, subjective factors of researchers and so on should be considered in establishing the retrieval model. According to the features of NOAA/AVHRR data from 1989 to 2008， a unified SST retrieval model is devised, and the 20year sequence data sets are established with the spatial resolution reached 1 km. The ship and buoy data, as well as OISST data, are used to evaluate the data sets，with the precision being around 1 ℃ (RMSE).The response of SST anomalies over the West Pacific warm pool to 1997/1998 El Nino is analyzed by using the retrieval data.
2012, 40(4):578-584.
Abstract:
A website construction method for publishing meteorological products based on the opensource IDV tool is introduced. The near realtime weather analysis maps are oriented towards the countylevel meteorological, agricultural, and public users at the browser end, with emphases on the temporalspatial multilevel covering of maps and meteorological services for farmers, mountain areas, and disaster management. The design principles are described in aspect of content, time, region, and interpretation, respectively. Using the ontology technology, the meteorological elements are converted into meteorological knowledge. The static and dynamic graphic layers are processed separately, in order to speed up the generation of the corresponding 2D and 3D maps. The web publishing platforms based on the proposed design have been applied in several sites and gained positive feedbacks.
A website construction method for publishing meteorological products based on the opensource IDV tool is introduced. The near realtime weather analysis maps are oriented towards the countylevel meteorological, agricultural, and public users at the browser end, with emphases on the temporalspatial multilevel covering of maps and meteorological services for farmers, mountain areas, and disaster management. The design principles are described in aspect of content, time, region, and interpretation, respectively. Using the ontology technology, the meteorological elements are converted into meteorological knowledge. The static and dynamic graphic layers are processed separately, in order to speed up the generation of the corresponding 2D and 3D maps. The web publishing platforms based on the proposed design have been applied in several sites and gained positive feedbacks.
2012, 40(4):585-590.
Abstract:
There are three problems in the Shaanxi Provincial Meteorological Service broadband communications network: the coexisting of three telecom suppliers, the messy using of IP addresses, and being unable to meet the requirement of multilink loading balancing and automatic switching between links. To solving those problems, a series of methods are adopted, such as standardizing the access methods for CMCC, CTC, and BCTV, and using the national unified IP addresses, and especially deploying the OSPF Dynamic Routing Selecting Protocol in the whole network. By adopting the OSPF protocol and such methods as dividing area reasonably and setting different configurations for the same or different OSPF costs as required, the automatic switching between different links and the traffic load balancing can be easily realized. The test indicates that the benefits of the multilink network are fully used，and the stability of network increased. The system can be used as references for the network designing of the like departments.
There are three problems in the Shaanxi Provincial Meteorological Service broadband communications network: the coexisting of three telecom suppliers, the messy using of IP addresses, and being unable to meet the requirement of multilink loading balancing and automatic switching between links. To solving those problems, a series of methods are adopted, such as standardizing the access methods for CMCC, CTC, and BCTV, and using the national unified IP addresses, and especially deploying the OSPF Dynamic Routing Selecting Protocol in the whole network. By adopting the OSPF protocol and such methods as dividing area reasonably and setting different configurations for the same or different OSPF costs as required, the automatic switching between different links and the traffic load balancing can be easily realized. The test indicates that the benefits of the multilink network are fully used，and the stability of network increased. The system can be used as references for the network designing of the like departments.
2012, 40(4):591-595.
Abstract:
XML, emerging as a standard for data representation and exchange on the Internet, plays an important role in varieties of applications. According to the analysis of the functional and performance requirements of WIS/GISC data access, a meteorological data subscription system is designed based on metadata presented by XML and the asynchronous communication mechanism. The background, usage, and scope of the subscription system are introduced. The scheme of describing meteorological metadata and order and dissemination information metadata represented by XML, the subscription functionality technology, the system design pattern, and the system workflow are given. The design has been implemented in the Beijing GISC system and meets the application requirements satisfactorily.
XML, emerging as a standard for data representation and exchange on the Internet, plays an important role in varieties of applications. According to the analysis of the functional and performance requirements of WIS/GISC data access, a meteorological data subscription system is designed based on metadata presented by XML and the asynchronous communication mechanism. The background, usage, and scope of the subscription system are introduced. The scheme of describing meteorological metadata and order and dissemination information metadata represented by XML, the subscription functionality technology, the system design pattern, and the system workflow are given. The design has been implemented in the Beijing GISC system and meets the application requirements satisfactorily.
2012, 40(4):596-600.
Abstract:
Using the conventional meteorological data, radar products, and automatic weather station data, the severe convective weather event on 28 June 2008 in Taiyuan is analyzed. The results show: (1) The configuration of the upperlevel cold vortex and the middlelower level wet and warm air mass provided the favorable circulation background for the severe convective weather. (2) The shape, structure, and VIL of the radar echoes showed strong convective characteristics, and the speed convergent zone corresponded well with the surface mesoscale convergence line, which means that there was strong wind shear along the vertical direction. (3) The hourtohour temperaturechange field revealed the path and the strength of the cold air intrusion, and the negative temperaturechange center would become severe convective weather area later. (4) The triggering mechanism of the severe convection was the surface mesoscale convergence line, and the negative center of the hourtohour pressurechange field corresponded with the ensuing severe weather area well. (5) Before the convection occurred, the single station meteorological elements showed notable discontinuous changes: pressure and relative humidity changed in the same direction, and temperature changed in the opposite direction; the three elements reached the peak values synchronously one hour before the severe weather event, and the severe weather occurred during the rapidly increasing period of the element values.
Using the conventional meteorological data, radar products, and automatic weather station data, the severe convective weather event on 28 June 2008 in Taiyuan is analyzed. The results show: (1) The configuration of the upperlevel cold vortex and the middlelower level wet and warm air mass provided the favorable circulation background for the severe convective weather. (2) The shape, structure, and VIL of the radar echoes showed strong convective characteristics, and the speed convergent zone corresponded well with the surface mesoscale convergence line, which means that there was strong wind shear along the vertical direction. (3) The hourtohour temperaturechange field revealed the path and the strength of the cold air intrusion, and the negative temperaturechange center would become severe convective weather area later. (4) The triggering mechanism of the severe convection was the surface mesoscale convergence line, and the negative center of the hourtohour pressurechange field corresponded with the ensuing severe weather area well. (5) Before the convection occurred, the single station meteorological elements showed notable discontinuous changes: pressure and relative humidity changed in the same direction, and temperature changed in the opposite direction; the three elements reached the peak values synchronously one hour before the severe weather event, and the severe weather occurred during the rapidly increasing period of the element values.
2012, 40(4):601-605.
Abstract:
Based on the compound index (CI) for meteorological droughts, using the Regional Dynamic Index (RDI) for meteorological droughts constructed from the classification of droughts，the application of RDI in the operational service is analyzed. Results indicate that the occurrence and development of droughts can be monitored and evaluated dynamically by using RDI. The index responds to the cumulative effects of droughts sufficiently, with the intensity evaluation of a drought not depended on the time period defined artificially. With characteristics of dynamic, consecutive and exercisable, the index is more applicable in depicting regional droughts in service practice, such as realtime monitoring, disaster warning, course evaluating, return period estimation, history rank judgment and so on. The application test of RDI to the 2009/2010 extreme drought event occurred in Yunnan Province indicates that the practical effect is better than that by using the classification of drought.
Based on the compound index (CI) for meteorological droughts, using the Regional Dynamic Index (RDI) for meteorological droughts constructed from the classification of droughts，the application of RDI in the operational service is analyzed. Results indicate that the occurrence and development of droughts can be monitored and evaluated dynamically by using RDI. The index responds to the cumulative effects of droughts sufficiently, with the intensity evaluation of a drought not depended on the time period defined artificially. With characteristics of dynamic, consecutive and exercisable, the index is more applicable in depicting regional droughts in service practice, such as realtime monitoring, disaster warning, course evaluating, return period estimation, history rank judgment and so on. The application test of RDI to the 2009/2010 extreme drought event occurred in Yunnan Province indicates that the practical effect is better than that by using the classification of drought.
2012, 40(4):606-612.
Abstract:
Based on the conventional data, automatic weather station data, Doppler radar observational data, etc., the causes of two heavy rainfall events occurred on 18 June and 7 July 2010 in the mountainous northwestern Fujian are compared and analyzed. The results show that both of the two processes happened under the circulation condition of the southwardmoving cold air guided by the eastmoving upperlevel trough and the interaction of the southwest jet with the strong wind speed convergence over the northern and central Fujian, integrating with rich water vapor, strong vertical ascending motion, and unstable atmosphere stratification. The position of the subtropical high, the horizontal width of the southwest jet, and the forwardtilting trough are the important influencing factors of the duration and scope of the heavy rainstorm. The storm strength is positively correlated with the vertical ascending motion and the suction effects of lowerlevel convergence and upper level divergence, etc. The maximum center of water vapor flux and water vapor flux divergence over the storm zone appeared earlier than heavy rainfall. The variation of water vapor has indicative significance for the forecasting and early warning of disasters weather. The radar echoes of the two rainstorms exhibit a zonal distribution, and the moving direction of the strong radar echo intensity center is consistent with the long axis of the echo center.
Based on the conventional data, automatic weather station data, Doppler radar observational data, etc., the causes of two heavy rainfall events occurred on 18 June and 7 July 2010 in the mountainous northwestern Fujian are compared and analyzed. The results show that both of the two processes happened under the circulation condition of the southwardmoving cold air guided by the eastmoving upperlevel trough and the interaction of the southwest jet with the strong wind speed convergence over the northern and central Fujian, integrating with rich water vapor, strong vertical ascending motion, and unstable atmosphere stratification. The position of the subtropical high, the horizontal width of the southwest jet, and the forwardtilting trough are the important influencing factors of the duration and scope of the heavy rainstorm. The storm strength is positively correlated with the vertical ascending motion and the suction effects of lowerlevel convergence and upper level divergence, etc. The maximum center of water vapor flux and water vapor flux divergence over the storm zone appeared earlier than heavy rainfall. The variation of water vapor has indicative significance for the forecasting and early warning of disasters weather. The radar echoes of the two rainstorms exhibit a zonal distribution, and the moving direction of the strong radar echo intensity center is consistent with the long axis of the echo center.
2012, 40(4):613-619.
Abstract:
Using the data of precipitation and NCEP in Anhui, two continues severe snow processes in 1969 and 2008 are studied, with emphases on the change of the blocking high in the Ural Mountain and the southwest wind over the south of Anhui at 700 hPa. It is found out that before both sever snow processes, the blocking high in the Ural Mountain was strong, and the two snow processes began from the weakening of the blocking high; about 1 or 2 days before or after the index of the blocking high dropping to the lowest, the southwest wind being strong at the same time, the snow enhanced obviously. The quasibiweekly oscillation of the moisture transport in the south of Anhui at 700h Pa was obvious in January and February in the two years. The water vapor origin of precipitation was from the South China Sea in 1969, and from the Bay of Bengal and the South China Sea in 2008
Using the data of precipitation and NCEP in Anhui, two continues severe snow processes in 1969 and 2008 are studied, with emphases on the change of the blocking high in the Ural Mountain and the southwest wind over the south of Anhui at 700 hPa. It is found out that before both sever snow processes, the blocking high in the Ural Mountain was strong, and the two snow processes began from the weakening of the blocking high; about 1 or 2 days before or after the index of the blocking high dropping to the lowest, the southwest wind being strong at the same time, the snow enhanced obviously. The quasibiweekly oscillation of the moisture transport in the south of Anhui at 700h Pa was obvious in January and February in the two years. The water vapor origin of precipitation was from the South China Sea in 1969, and from the Bay of Bengal and the South China Sea in 2008
2012, 40(4):620-626.
Abstract:
Lightning, rainfall, and radar features of two thunderstorms in Nantong in 2009 are analyzed in detail with the data from the lightning location system, Doppler radar, radiosondes and rainfall data. Results show that lightning strokes mainly concentrated within the strong radar echo area, especially in the area of over 40 dBz radar echo, while some, in particular positive lightning, occurred on the edge of strong area or the weak area. The echo height of 40dBz echo reached the -10 ℃ level before the first lightning, being consistent with the variation of lightning frequency. The area of radar echo more than 40 dBz varied with the frequency of lightning strokes almost simultaneously, and the lightning frequency decreased during the rainfall though the echo area was big. There was good correlation among the frequency of lightning strokes happened around 20 km and the hourly average area of radar echo more than 40dBz.
Lightning, rainfall, and radar features of two thunderstorms in Nantong in 2009 are analyzed in detail with the data from the lightning location system, Doppler radar, radiosondes and rainfall data. Results show that lightning strokes mainly concentrated within the strong radar echo area, especially in the area of over 40 dBz radar echo, while some, in particular positive lightning, occurred on the edge of strong area or the weak area. The echo height of 40dBz echo reached the -10 ℃ level before the first lightning, being consistent with the variation of lightning frequency. The area of radar echo more than 40 dBz varied with the frequency of lightning strokes almost simultaneously, and the lightning frequency decreased during the rainfall though the echo area was big. There was good correlation among the frequency of lightning strokes happened around 20 km and the hourly average area of radar echo more than 40dBz.
2012, 40(4):627-634.
Abstract:
By use of conventional data, as well as AWS, FY2C TBB and Doppler weather radar data, the causes of a regional rainstorm occurred in Shandong from 9 to 10 May 2009 are analyzed. The results indicate: (1) The severe precipitation was produced when the cold air met with the southwest warm wet air. The stronger subtropical high made the surface convergence line and the shear line at 850 and 700 hPa stagnated; therefore, the severe precipitation is maintained persistently. (2) The formation and maintenance of the surface convergence lines stimulated ascending motion in the boundary layer and provided sufficient water vapor for the storm, and the cold air met with the warm wet air, leading to the convergence and updraft. As a result, the ascending movement strengthened and the precipitation increased. (3) The mesoscale convective system (MCS) was the major influencing system, and many multicell storms alternated and moved through the same region to form “train effect” and produce a regional rainstorm. (4) The lowlevel jets of different heights and the head wind zone in the radar radial velocity chart have indicative significance to severe precipitation forecasting.
By use of conventional data, as well as AWS, FY2C TBB and Doppler weather radar data, the causes of a regional rainstorm occurred in Shandong from 9 to 10 May 2009 are analyzed. The results indicate: (1) The severe precipitation was produced when the cold air met with the southwest warm wet air. The stronger subtropical high made the surface convergence line and the shear line at 850 and 700 hPa stagnated; therefore, the severe precipitation is maintained persistently. (2) The formation and maintenance of the surface convergence lines stimulated ascending motion in the boundary layer and provided sufficient water vapor for the storm, and the cold air met with the warm wet air, leading to the convergence and updraft. As a result, the ascending movement strengthened and the precipitation increased. (3) The mesoscale convective system (MCS) was the major influencing system, and many multicell storms alternated and moved through the same region to form “train effect” and produce a regional rainstorm. (4) The lowlevel jets of different heights and the head wind zone in the radar radial velocity chart have indicative significance to severe precipitation forecasting.
2012, 40(4):635-641.
Abstract:
Based on Doppler Weather Radar data, weather maps and satellite cloudy products, a largescale rainfall on 18 April 2009 in Tianjin is analyzed. The characteristics of Doppler Weather Radar products and the distribution of cloud parameters during this rainfall process are discussed. The results show that：(1) it was a stratocumulus mix cloud precipitation process, affected by the Hetao low trough at 500 hPa and surface cyclones over the YangtzeHuaihe River Valley; (2) the reflectivity of Doppler Radar presented the obvious multiphased characteristic: forming, developing, maintaining, and weakening with the complete wind profiler data; (3) during the MODIS satellite passing time, the effective radius of cloud particles was above 15 μm, and the particle radius with the highest appearance frequency was 25 to 27μm. The area with the maximum atmospheric potential precipitation was consistent with the hourly precipitation of the automatic rainfall station.
Based on Doppler Weather Radar data, weather maps and satellite cloudy products, a largescale rainfall on 18 April 2009 in Tianjin is analyzed. The characteristics of Doppler Weather Radar products and the distribution of cloud parameters during this rainfall process are discussed. The results show that：(1) it was a stratocumulus mix cloud precipitation process, affected by the Hetao low trough at 500 hPa and surface cyclones over the YangtzeHuaihe River Valley; (2) the reflectivity of Doppler Radar presented the obvious multiphased characteristic: forming, developing, maintaining, and weakening with the complete wind profiler data; (3) during the MODIS satellite passing time, the effective radius of cloud particles was above 15 μm, and the particle radius with the highest appearance frequency was 25 to 27μm. The area with the maximum atmospheric potential precipitation was consistent with the hourly precipitation of the automatic rainfall station.
2012, 40(4):642-646.
Abstract:
The weather circulation background and dynamic mechanisms for a sandstorm case occurred in the western Inner Mongolia on 23 April 2009 are analyzed by using observation data. The results show that the main cause for this sandstorm case is strong cold air activities. The upperlevel system causing the sandstorm is the deep Mongolian transverse trough and northerly airflow on the east; the surface system is the strongly developing Mongolian cyclone. From the view point of dynamics, when the sandstorm happened, the momentum of northerly airflow aloft was transmitted downward to surface with prevailing descending motion because of convergence at upper levels and divergence at lower levels. The secondary circulation generated by disturbance development at middle and low levels made momentum transmit downward effectively. It is worthy to note that the key points for the storm are the southward movement of the upper Mongolian transverse trough and its rotation to upright position, which caused clod air to break and move southward; the upper northerly jet and the obvious development of the surface Mongolian cyclone around the exit of the jet were the necessary conditions for sandstorm generation; the continuous reinforcement of pressure gradient after the surface cold front speeding up intensified the burst of clod air; and the strong convergence aloft and divergence below increased the possibility for sandstorm generation.
The weather circulation background and dynamic mechanisms for a sandstorm case occurred in the western Inner Mongolia on 23 April 2009 are analyzed by using observation data. The results show that the main cause for this sandstorm case is strong cold air activities. The upperlevel system causing the sandstorm is the deep Mongolian transverse trough and northerly airflow on the east; the surface system is the strongly developing Mongolian cyclone. From the view point of dynamics, when the sandstorm happened, the momentum of northerly airflow aloft was transmitted downward to surface with prevailing descending motion because of convergence at upper levels and divergence at lower levels. The secondary circulation generated by disturbance development at middle and low levels made momentum transmit downward effectively. It is worthy to note that the key points for the storm are the southward movement of the upper Mongolian transverse trough and its rotation to upright position, which caused clod air to break and move southward; the upper northerly jet and the obvious development of the surface Mongolian cyclone around the exit of the jet were the necessary conditions for sandstorm generation; the continuous reinforcement of pressure gradient after the surface cold front speeding up intensified the burst of clod air; and the strong convergence aloft and divergence below increased the possibility for sandstorm generation.
2012, 40(4):647-650.
Abstract:
An analysis is made of a severe storm occurred on 17 July 2009 in the Shandong peninsula by using the 〖WTBX〗V3θ〖WTBZ〗 chart based on the analysis software of MICAPS (3rd edition). The results show that the 〖WTBX〗V3〖WTBX〗θ〖WTBZ〗 chart can reveal the signs of severe storms. The ultralow temperature at the tropospheric top, cold air intruding into the middlelevel troposphere, the caused severe convection, and abundant moisture at lower levels are the causes of the severe storm. The 〖WTBX〗V3θ〖WTBZ〗 charts of the upstream stations can be used to estimate the direction and intensity of moisture transport. The difference in the underlying surface between sea and land is also an important cause of the severe storm. The characteristics of the 〖WTBX〗V3θ〖WTBZ〗 chart are useful in forecasting severe storms more than 12 hours in advance.
An analysis is made of a severe storm occurred on 17 July 2009 in the Shandong peninsula by using the 〖WTBX〗V3θ〖WTBZ〗 chart based on the analysis software of MICAPS (3rd edition). The results show that the 〖WTBX〗V3〖WTBX〗θ〖WTBZ〗 chart can reveal the signs of severe storms. The ultralow temperature at the tropospheric top, cold air intruding into the middlelevel troposphere, the caused severe convection, and abundant moisture at lower levels are the causes of the severe storm. The 〖WTBX〗V3θ〖WTBZ〗 charts of the upstream stations can be used to estimate the direction and intensity of moisture transport. The difference in the underlying surface between sea and land is also an important cause of the severe storm. The characteristics of the 〖WTBX〗V3θ〖WTBZ〗 chart are useful in forecasting severe storms more than 12 hours in advance.
2012, 40(4):651-655.
Abstract:
The causes of frequently occurred lightning accidents in the Chengnan Middle School of Dazu County, Chongqing after a mobile communication base station was constructed are analyzed by means of the monitoring data of the ADTD lightning location system in Chongqing from 2006 to 2009 The results show that the construction of the mobile communication iron tower increased the lightning strike probability of the Chengnan Middle School and the influence of lightning electromagnetic impulses, which is the major cause of the frequently occurred lightning accidents. The teaching building frequently stroke is out of the protective range of the iron tower, located in the lightning scattered strike zone of the iron tower, and does not have lightning protection devices.
The causes of frequently occurred lightning accidents in the Chengnan Middle School of Dazu County, Chongqing after a mobile communication base station was constructed are analyzed by means of the monitoring data of the ADTD lightning location system in Chongqing from 2006 to 2009 The results show that the construction of the mobile communication iron tower increased the lightning strike probability of the Chengnan Middle School and the influence of lightning electromagnetic impulses, which is the major cause of the frequently occurred lightning accidents. The teaching building frequently stroke is out of the protective range of the iron tower, located in the lightning scattered strike zone of the iron tower, and does not have lightning protection devices.
2012, 40(4):656-660.
Abstract:
The radiation field characteristics of cloudtoground (CG) lightning flashes in the Daxing’an Mountain Range are analyzed and compared with those of other researches from home and abroad by using the data obtained from a broadband slow antenna system with a high time resolution. It is found that for 35 positive CG flashes, the average duration of the slowchange period and the 10% to 90% rising period for the first return strokes are 78 μs and 45 μs, respectively, in 11 of which the average crossing time and overshoot depth are 34 μs and 23%, respectively; for 76 negative CG flashes, those are 35 μs and 19 μs, respectively, in 15 of which the crossing time and overshoot depth are 51 μs and 52%, respectively. The average half peak width of first return strokes of positive CG flashes is larger than that of negative CG flashes, with the average values being 136 μs and 56 μs. Compared with other observations both from home and abroad, the characteristics of radiation fields of return strokes of CG flashes at the Daxing’an Mountain Range are similar with those in Sweden and Florida of America, but different from those on the QinghaiTibet plateau.
The radiation field characteristics of cloudtoground (CG) lightning flashes in the Daxing’an Mountain Range are analyzed and compared with those of other researches from home and abroad by using the data obtained from a broadband slow antenna system with a high time resolution. It is found that for 35 positive CG flashes, the average duration of the slowchange period and the 10% to 90% rising period for the first return strokes are 78 μs and 45 μs, respectively, in 11 of which the average crossing time and overshoot depth are 34 μs and 23%, respectively; for 76 negative CG flashes, those are 35 μs and 19 μs, respectively, in 15 of which the crossing time and overshoot depth are 51 μs and 52%, respectively. The average half peak width of first return strokes of positive CG flashes is larger than that of negative CG flashes, with the average values being 136 μs and 56 μs. Compared with other observations both from home and abroad, the characteristics of radiation fields of return strokes of CG flashes at the Daxing’an Mountain Range are similar with those in Sweden and Florida of America, but different from those on the QinghaiTibet plateau.
2012, 40(4):661-665.
Abstract:
Mobile meteorological stations play an important role in the emergency support of sudden meteorological disasters, which often park around tall buildings or in unoccupied areas in severe weather, so they are easy to become the main object of lightning. Considering that a mobile meteorological station generally consists of two parts (communication unit and vehicleborne radar) with a relatively fixed parking position, the lightning protection approach of multilevel fortification and comprehensive management for a mobile meteorological station is presented, based on the existing lightning protection standards of metrological and communication industries, and some specific suggestions about the installation and construction of lightning protection facilities are discussed in detail, which are useful to the lightning protection of mobile meteorological stations.
Mobile meteorological stations play an important role in the emergency support of sudden meteorological disasters, which often park around tall buildings or in unoccupied areas in severe weather, so they are easy to become the main object of lightning. Considering that a mobile meteorological station generally consists of two parts (communication unit and vehicleborne radar) with a relatively fixed parking position, the lightning protection approach of multilevel fortification and comprehensive management for a mobile meteorological station is presented, based on the existing lightning protection standards of metrological and communication industries, and some specific suggestions about the installation and construction of lightning protection facilities are discussed in detail, which are useful to the lightning protection of mobile meteorological stations.
2012, 40(4):666-670.
Abstract:
Based on the observational data from the groundbased GPS (Global Positioning System) network in Chengdu Plain, the Precipitable Water Vapor (PWV) in the atmosphere is calculated. The Vertical Integrated Liquid water content (VIL) is derived from the Doppler radar detection data. Analysis is made of the variation characteristics of water vapor during weather modification operations by means of those new detection data. The relationship between GPS PWV and rainfall after weather modification operation is obtained preliminarily. The results show that there is a good corresponding relation between GPS PWV and artificial precipitation enhancement; GPS PWV decreases with the increasing rainfall intensity in 1 to 3 hours after the weather modification operation, which reflects that catalysts lead the partial supersaturated vapor over ice layer to convert into precipitation. GPS PWV, in combination with VIL detected by a new generation of Doppler radar, has good application prospects in weather modification operations and shortterm weather forecasting and nowcasting.
Based on the observational data from the groundbased GPS (Global Positioning System) network in Chengdu Plain, the Precipitable Water Vapor (PWV) in the atmosphere is calculated. The Vertical Integrated Liquid water content (VIL) is derived from the Doppler radar detection data. Analysis is made of the variation characteristics of water vapor during weather modification operations by means of those new detection data. The relationship between GPS PWV and rainfall after weather modification operation is obtained preliminarily. The results show that there is a good corresponding relation between GPS PWV and artificial precipitation enhancement; GPS PWV decreases with the increasing rainfall intensity in 1 to 3 hours after the weather modification operation, which reflects that catalysts lead the partial supersaturated vapor over ice layer to convert into precipitation. GPS PWV, in combination with VIL detected by a new generation of Doppler radar, has good application prospects in weather modification operations and shortterm weather forecasting and nowcasting.
2012, 40(4):671-675.
Abstract:
According to the characteristics of work safety and requirements for port operations, the hydrometeorological forecasting system for Tianjin Harbor is a practical professional platform, integrating monitoring with forecasting results for hydrometeorological elements, which has the following features: the large amount of information, access to information timely, and userfriendly. Applying atmospheric model (WRF), ocean models (ADI and ECOM), and wave formula, which were tested by the observed data of automatic stations, the system provides forecast and related visual products in the four aspects: fog, gale, wave, and storm surge.
According to the characteristics of work safety and requirements for port operations, the hydrometeorological forecasting system for Tianjin Harbor is a practical professional platform, integrating monitoring with forecasting results for hydrometeorological elements, which has the following features: the large amount of information, access to information timely, and userfriendly. Applying atmospheric model (WRF), ocean models (ADI and ECOM), and wave formula, which were tested by the observed data of automatic stations, the system provides forecast and related visual products in the four aspects: fog, gale, wave, and storm surge.
2012, 40(4):676-679.
Abstract:
Based on the actual snow disaster data over the Qinghai plateau from 1951 to 2008, the mortality rates of livestock caused by snow disasters are calculated, referring to the proportion of droughts of various levels in SPI (Standardized Precipitation Index) calculation to determine the threshold values for the snow disaster of a certain level. The indexes for snow disasters are devised based on the actual disasters and tested on several typical snow disasters. The results show that the indexes are in accord with the standards of DB63 In the pasturing area of the Qinghai plateau, it is a more reasonable and practical method to establish the indexes of snow disasters and to determine the level of a snow disaster by using the mortality rate of livestock caused by snow disasters.
Based on the actual snow disaster data over the Qinghai plateau from 1951 to 2008, the mortality rates of livestock caused by snow disasters are calculated, referring to the proportion of droughts of various levels in SPI (Standardized Precipitation Index) calculation to determine the threshold values for the snow disaster of a certain level. The indexes for snow disasters are devised based on the actual disasters and tested on several typical snow disasters. The results show that the indexes are in accord with the standards of DB63 In the pasturing area of the Qinghai plateau, it is a more reasonable and practical method to establish the indexes of snow disasters and to determine the level of a snow disaster by using the mortality rate of livestock caused by snow disasters.
2012, 40(4):680-684.
Abstract:
Based on the data from 27 meteorological observing towers over South China for one year, it is found that the average wind power density index is less than the threefold wind speed index. The variation law between annual mean wind and shape parameter with height and a new method for estimating the average wind energy density at different heights are discussed. The results show that the average relative error of this method is 96%, which provides references for computing the wind power density so to estimate the variation of wind energy with height for the stations without gradient wind observation.
Based on the data from 27 meteorological observing towers over South China for one year, it is found that the average wind power density index is less than the threefold wind speed index. The variation law between annual mean wind and shape parameter with height and a new method for estimating the average wind energy density at different heights are discussed. The results show that the average relative error of this method is 96%, which provides references for computing the wind power density so to estimate the variation of wind energy with height for the stations without gradient wind observation.
2012, 40(4):685-688.
Abstract:
By means of the TM satellite remote sensing data (1999 to 2004, 2008, and 2009) and temperature, precipitation meteorological data (1999 to 2009),an analysis is conducted by means of ARCGIS, ARCVIEW, ENVI saftware. It is concluded that the area of Lake Tangra Yumco presented an enlarging trend significantly in nearly 11 years. The area of Lake Tangra Yumco increased to 85201 km2 in 2009 from 83697 km2 in 1999, and the most obvious enlargement is found in the southeastern part of the lake. The rising temperature, which resulted in the melting of the glaciers and permanent snow cover around the basin, and the increasing precipitation of the lake are the major causes.
By means of the TM satellite remote sensing data (1999 to 2004, 2008, and 2009) and temperature, precipitation meteorological data (1999 to 2009),an analysis is conducted by means of ARCGIS, ARCVIEW, ENVI saftware. It is concluded that the area of Lake Tangra Yumco presented an enlarging trend significantly in nearly 11 years. The area of Lake Tangra Yumco increased to 85201 km2 in 2009 from 83697 km2 in 1999, and the most obvious enlargement is found in the southeastern part of the lake. The rising temperature, which resulted in the melting of the glaciers and permanent snow cover around the basin, and the increasing precipitation of the lake are the major causes.
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.