Volume 47,Issue 5,2019 Table of Contents
2019, 47(5):719-730.
Abstract:
The methods for using single Doppler radar to retrieve the vortex wind fields are rare currently. This article compares three methods: NIVAP, EVAPTC, GBVTD, which can retrieve the vortex wind fields, from the aspects of assumptions, mathematical methods, and the retrieval accuracy, so to identify which is most suitable for the vortex wind field. Using the Rankine mode mesoscale cyclone to simulate the Doppler velocity and wind field with the vortex wind field only, with the environmental wind, and with both environmental wind and convergence (divergence). The similarity coefficients of wind velocity and wind direction between the simulated and the retrieval wind fields are compared. After comparing the simulated wind field, the measured data of Typhoon Rammasun at the time of one hour before landing, right landing and one hour after landing are selected. Then the characteristics of the retrieval wind fields by the three methods are compared and analyzed. The analysis shows that EVAPTC has a good performance, GBVTD has some restrictions in practical application, and NIVAP performs poorly.
The methods for using single Doppler radar to retrieve the vortex wind fields are rare currently. This article compares three methods: NIVAP, EVAPTC, GBVTD, which can retrieve the vortex wind fields, from the aspects of assumptions, mathematical methods, and the retrieval accuracy, so to identify which is most suitable for the vortex wind field. Using the Rankine mode mesoscale cyclone to simulate the Doppler velocity and wind field with the vortex wind field only, with the environmental wind, and with both environmental wind and convergence (divergence). The similarity coefficients of wind velocity and wind direction between the simulated and the retrieval wind fields are compared. After comparing the simulated wind field, the measured data of Typhoon Rammasun at the time of one hour before landing, right landing and one hour after landing are selected. Then the characteristics of the retrieval wind fields by the three methods are compared and analyzed. The analysis shows that EVAPTC has a good performance, GBVTD has some restrictions in practical application, and NIVAP performs poorly.
2019, 47(5):731-739.
Abstract:
There is big rain attenuation when the XBand Dualpolarization weather radar observes heavy precipitation, as the phase parameter of dualpolarization has little attenuation, so it can be used for correcting the reflectivity. The selfconsistent algorithm and 〖WTBX〗K〖WTBZ〗DP method are two kinds of attenuation correction algorithms that are applied relatively frequently. Both methods use differential parameters to achieve attenuation correction. The selfconsistent algorithm is difficult to achieve, but it can adjust the correction coefficient according to different precipitation types, while the 〖WTBX〗K〖WTBZ〗DP method cannot be realized. In this paper, the 〖WTBX〗K〖WTBZ〗DP complexclassification method is proposed, which is easier to implement, based on the selfconsistent algorithm and 〖WTBX〗K〖WTBZ〗DP methods. We complete the attenuation correction by three methods respectively, and then compared and analyzed the correction effect, also compared with the SBand radar. The reflectivities before and after correction are compared with the ground precipitation observation data. The results show that the corrected reflectivity is more suitable for precipitation observation and inversion.
There is big rain attenuation when the XBand Dualpolarization weather radar observes heavy precipitation, as the phase parameter of dualpolarization has little attenuation, so it can be used for correcting the reflectivity. The selfconsistent algorithm and 〖WTBX〗K〖WTBZ〗DP method are two kinds of attenuation correction algorithms that are applied relatively frequently. Both methods use differential parameters to achieve attenuation correction. The selfconsistent algorithm is difficult to achieve, but it can adjust the correction coefficient according to different precipitation types, while the 〖WTBX〗K〖WTBZ〗DP method cannot be realized. In this paper, the 〖WTBX〗K〖WTBZ〗DP complexclassification method is proposed, which is easier to implement, based on the selfconsistent algorithm and 〖WTBX〗K〖WTBZ〗DP methods. We complete the attenuation correction by three methods respectively, and then compared and analyzed the correction effect, also compared with the SBand radar. The reflectivities before and after correction are compared with the ground precipitation observation data. The results show that the corrected reflectivity is more suitable for precipitation observation and inversion.
2019, 47(5):740-746.
Abstract:
To measure the applicability of 10m wind field data inverted by ASCAT in Qingdao, we compare the differences between ASCAT coastal wind products and observed 10m wind field data from buoy and island stations. The analysis results show that the ASCAT inversion wind speed is larger and the wind direction is more left than observed wind from buoy and island stations, but the deviation is small. The deviations of the wind speed and wind direction of the ASCAT inversion wind field and the observed wind are 1.6 m/s and -9.6°, respectively. The ASCAT inversion wind field has good applicability in the coastal area of Qingdao, and a more detailed wind field space along the coast of Qingdao. From the comparison of wind speed grading, the weaker the wind speed, the better the satellite inversion wind speed result, and the wind direction is the opposite. The inversion of wind speed and wind direction is better in the evening than in the morning. Seasonal changes have little effect on wind speed inversion, but have a certain impact on wind direction inversion. The wind direction inversion results in autumn and winter are better than in spring and summer. The linear regression correction, comprehensive error, wind speed level error and lifting rail error correction were performed for the ASCAT inversion wind speed, and the linear regression correction result was found to be the best.
To measure the applicability of 10m wind field data inverted by ASCAT in Qingdao, we compare the differences between ASCAT coastal wind products and observed 10m wind field data from buoy and island stations. The analysis results show that the ASCAT inversion wind speed is larger and the wind direction is more left than observed wind from buoy and island stations, but the deviation is small. The deviations of the wind speed and wind direction of the ASCAT inversion wind field and the observed wind are 1.6 m/s and -9.6°, respectively. The ASCAT inversion wind field has good applicability in the coastal area of Qingdao, and a more detailed wind field space along the coast of Qingdao. From the comparison of wind speed grading, the weaker the wind speed, the better the satellite inversion wind speed result, and the wind direction is the opposite. The inversion of wind speed and wind direction is better in the evening than in the morning. Seasonal changes have little effect on wind speed inversion, but have a certain impact on wind direction inversion. The wind direction inversion results in autumn and winter are better than in spring and summer. The linear regression correction, comprehensive error, wind speed level error and lifting rail error correction were performed for the ASCAT inversion wind speed, and the linear regression correction result was found to be the best.
2019, 47(5):747-751.
Abstract:
Negative air ion concentration is an important criterion for judging air quality. The traditional negative air ion concentration detector measures the current formed at the two ends of the collector plate by a capacitive ion collector, and calculates the concentration by the relationship between the measured current and the negative ion concentration. The negative air ion concentration detector designed by this method can only measure the concentration of a limited number of radius, and there is a certain systematic error in measuring the concentration of a large radius. In order to meet the requirement of high precision detection of negative air ion concentration, a method of detecting negative air ion concentration based on mobility analysis is proposed by simulating and analyzing the trajectories of air ions with different radius in the collector. The corresponding circuit system and design parameters are given, and the rationality of the system design is analyzed and demonstrated. This method combines current detection with numerical calculation, and can accurately measure the concentration of negative ions with different radius in the air. It has important application value in the field of environmental monitoring and assessment.
Negative air ion concentration is an important criterion for judging air quality. The traditional negative air ion concentration detector measures the current formed at the two ends of the collector plate by a capacitive ion collector, and calculates the concentration by the relationship between the measured current and the negative ion concentration. The negative air ion concentration detector designed by this method can only measure the concentration of a limited number of radius, and there is a certain systematic error in measuring the concentration of a large radius. In order to meet the requirement of high precision detection of negative air ion concentration, a method of detecting negative air ion concentration based on mobility analysis is proposed by simulating and analyzing the trajectories of air ions with different radius in the collector. The corresponding circuit system and design parameters are given, and the rationality of the system design is analyzed and demonstrated. This method combines current detection with numerical calculation, and can accurately measure the concentration of negative ions with different radius in the air. It has important application value in the field of environmental monitoring and assessment.
2019, 47(5):752-756.
Abstract:
In view of the shortcomings of the field calibration method of wind speed sensors in service, this paper discusses the improvement of the calibration equipment of cup wind speed sensors widely used by meteorological departments, and uses the startup wind speed calibrator to calibrate the wind speed sensors in low wind speed section, so as to solve the problem that the wind speed calibrator cannot detect the overall performance of wind speed sensors, and realizes the instrument traceability of cup wind speed sensors and reaches the laboratory wind tunnel standards. After calibrating the wind speed sensors with the improved field calibration method, the fitting linear regression equation is compared with the wind tunnel calibration results. It is found that the improved method can basically meet the needs of the field calibration of wind speed sensors.
In view of the shortcomings of the field calibration method of wind speed sensors in service, this paper discusses the improvement of the calibration equipment of cup wind speed sensors widely used by meteorological departments, and uses the startup wind speed calibrator to calibrate the wind speed sensors in low wind speed section, so as to solve the problem that the wind speed calibrator cannot detect the overall performance of wind speed sensors, and realizes the instrument traceability of cup wind speed sensors and reaches the laboratory wind tunnel standards. After calibrating the wind speed sensors with the improved field calibration method, the fitting linear regression equation is compared with the wind tunnel calibration results. It is found that the improved method can basically meet the needs of the field calibration of wind speed sensors.
2019, 47(5):757-767.
Abstract:
Wind profiler radar is a kind of clearair wind measuring equipment which mainly detects atmospheric turbulence, with extensive application and the increasing availability. In this paper, two types of grid wind profiler radar of type 1456D/F are taken as the research object, 22 product anomalies are collected and classified, and the causes of data product anomalies are analyzed. At the same time, based on data product anomalies, this paper summarizes a set of empirical methods and troubleshooting procedures for identifying and analyzing wind profile radar faults. The relevant conclusions of this paper are conducive to improving the capability of provincial and station operators to identify abnormal data products of wind profile radar, effectively ensuring the normal collection and uploading of data, and thus providing more accurate detection data for forecasting services.
Wind profiler radar is a kind of clearair wind measuring equipment which mainly detects atmospheric turbulence, with extensive application and the increasing availability. In this paper, two types of grid wind profiler radar of type 1456D/F are taken as the research object, 22 product anomalies are collected and classified, and the causes of data product anomalies are analyzed. At the same time, based on data product anomalies, this paper summarizes a set of empirical methods and troubleshooting procedures for identifying and analyzing wind profile radar faults. The relevant conclusions of this paper are conducive to improving the capability of provincial and station operators to identify abnormal data products of wind profile radar, effectively ensuring the normal collection and uploading of data, and thus providing more accurate detection data for forecasting services.
2019, 47(5):768-772.
Abstract:
Under the distributed computing and storage framework of Hadoop, according to the customed ETL data cleaning rules, based on its year in which it belongs and station number, the hourly singlestation files of mass automatic station data are merged into large files and transferred to the distributed storage HDFS， using the Spark SQL parallel computation framework to deal with and produce the daily statistical values of common meteorological elements, which greatly improves data processing and acquisition efficiency compared with the relational database. The experimental results show that the data processing and querying of multiple meteorological elements, multisite data and longtime series can reach the second level response by using the SparkSQL parallel computing framework, and its advantages are more obvious with the increasing number of statistical sites and the extension of time span. It can support this kind of meteorological data service more efficiently and provide new ideas for the transformation of largescale meteorological data processing from relational database to large data distributed framework.
Under the distributed computing and storage framework of Hadoop, according to the customed ETL data cleaning rules, based on its year in which it belongs and station number, the hourly singlestation files of mass automatic station data are merged into large files and transferred to the distributed storage HDFS， using the Spark SQL parallel computation framework to deal with and produce the daily statistical values of common meteorological elements, which greatly improves data processing and acquisition efficiency compared with the relational database. The experimental results show that the data processing and querying of multiple meteorological elements, multisite data and longtime series can reach the second level response by using the SparkSQL parallel computing framework, and its advantages are more obvious with the increasing number of statistical sites and the extension of time span. It can support this kind of meteorological data service more efficiently and provide new ideas for the transformation of largescale meteorological data processing from relational database to large data distributed framework.
2019, 47(5):773-779.
Abstract:
The destination of the regional station data transmission around the nation is transformed from the municipal center to the provincial center. The adjustment of regional station data transmission brings some challenges to the regional station operation and maintenance support of provincial level, municipal level and county level. In order to solve the difficulties in the unified management, monitoring and fault diagnosis, a provincial monitoring system for data direct transmission between regional stations is designed and implemented. CIMISS and the provincial regional center are the foundation of the provincial operation and maintenance support system based on the Django framework. The system can monitor and display the flow link of the CIMISS CTS, provincial regional center, regional station data sources and regional station batteries. The system can also display the regional station data transmission history and diagnostic faults and has come into service, which can improve the capability of operation and maintenance support for regional station data transmission.
The destination of the regional station data transmission around the nation is transformed from the municipal center to the provincial center. The adjustment of regional station data transmission brings some challenges to the regional station operation and maintenance support of provincial level, municipal level and county level. In order to solve the difficulties in the unified management, monitoring and fault diagnosis, a provincial monitoring system for data direct transmission between regional stations is designed and implemented. CIMISS and the provincial regional center are the foundation of the provincial operation and maintenance support system based on the Django framework. The system can monitor and display the flow link of the CIMISS CTS, provincial regional center, regional station data sources and regional station batteries. The system can also display the regional station data transmission history and diagnostic faults and has come into service, which can improve the capability of operation and maintenance support for regional station data transmission.
9 Design and Implementation of Smart TV Box Meteorological Service Software Based on Android System
2019, 47(5):780-785.
Abstract:
With the rapid development of the Android system and Internet technology, the smart TV box hardware technology has become one of the most promising industries. The main focus of this paper is the application software designation of smart TV boxes. In order to enrich the means of mobile meteorological information service, smart TV box meteorological service software (weather box) has been widely developed by either using Android, Nginx, Web service or other technical solutions. In this paper, we detailed the newly designed hardware, i.e., system architecture and network topology. Then, we introduce software implementations. By using the newly proposed Load Balancing Strategy and Network Architecture Optimization, our production can dynamically be adaptive to those high concurrent users while maintaining the acceptable security level. Our product also follows the user experiences, which we previously received from our clients, to be convenient the operation process. The product can be potentially valuable as guidance for the relevance software designation towards smart TV boxes.
With the rapid development of the Android system and Internet technology, the smart TV box hardware technology has become one of the most promising industries. The main focus of this paper is the application software designation of smart TV boxes. In order to enrich the means of mobile meteorological information service, smart TV box meteorological service software (weather box) has been widely developed by either using Android, Nginx, Web service or other technical solutions. In this paper, we detailed the newly designed hardware, i.e., system architecture and network topology. Then, we introduce software implementations. By using the newly proposed Load Balancing Strategy and Network Architecture Optimization, our production can dynamically be adaptive to those high concurrent users while maintaining the acceptable security level. Our product also follows the user experiences, which we previously received from our clients, to be convenient the operation process. The product can be potentially valuable as guidance for the relevance software designation towards smart TV boxes.
2019, 47(5):786-794.
Abstract:
By using the monthlymean precipitation data provided by the National Meteorological Information Center and NCEP/NCAR reanalysis project and SST (Sea Surface Temperature) data from the Hadley Center, the predictable modes of summer precipitation in the eastern Tibetan plateau are extracted based on the Predictable Modal Analysis (PMA) method. According to the existing researches, the appropriate predictors are selected and the physicalempirical (PE) model is established. The study applies the statistical prediction method to predict summer precipitation in the eastern part of the plateau. The results show that the four dominant modes, i.e., the northsouth reversal mode, uniform mode, middle mode and northeast mode, are predictable and meaningful, reflecting the anomalous variation of precipitation. The domainaveraged temporal correlation coefficient (TCC) skills of the 0month lead prediction and the 1month lead prediction are 0.44 and 0.36, respectively, which means that they are well predicted. The maximum is located in the southeast of the plateau. Timeaveraged pattern correlation coefficient (PCC) skills of the above two predictions are 0.46 and 0.42, respectively. For 0month lead prediction, the best year is 1998 and the worst is 1980, while for 1month lead prediction, the best year is 1998 and the worst is 2009.
By using the monthlymean precipitation data provided by the National Meteorological Information Center and NCEP/NCAR reanalysis project and SST (Sea Surface Temperature) data from the Hadley Center, the predictable modes of summer precipitation in the eastern Tibetan plateau are extracted based on the Predictable Modal Analysis (PMA) method. According to the existing researches, the appropriate predictors are selected and the physicalempirical (PE) model is established. The study applies the statistical prediction method to predict summer precipitation in the eastern part of the plateau. The results show that the four dominant modes, i.e., the northsouth reversal mode, uniform mode, middle mode and northeast mode, are predictable and meaningful, reflecting the anomalous variation of precipitation. The domainaveraged temporal correlation coefficient (TCC) skills of the 0month lead prediction and the 1month lead prediction are 0.44 and 0.36, respectively, which means that they are well predicted. The maximum is located in the southeast of the plateau. Timeaveraged pattern correlation coefficient (PCC) skills of the above two predictions are 0.46 and 0.42, respectively. For 0month lead prediction, the best year is 1998 and the worst is 1980, while for 1month lead prediction, the best year is 1998 and the worst is 2009.
2019, 47(5):795-808.
Abstract:
By using the ground and upperair observational data, Doppler radar data, FY2E satellite observational data and ERAInterim reanalysis data, the environmental conditions, mesoscale convective systems, the characteristics of Doppler radar reflectivity, the dynamiclifted condition, and forecasting hints are analyzed and compared between two warmsector heavy rain processes occurred on 17 Aug 2012 and 16 July 2017 in the Western Sichuan basin. The results show: (1) Both processes happened under the background of lowlevel warmmoist flows and ground thermal lows; the “12.08” heavy rain occurred on the edge of the subtropical high pressure system; the moisture transport condition was better; and the heavy rainfall maintained longer. The “17.07” heavy rain happened behind the upper vortexshear, the upper cold advection was more obvious, convective unstable energy was more abundant, and the convective system developed stronger. (2) The mesoscale convective system moved slowly on the edge of the subtropicalhigh pressure and had obvious traineffect during the “12.08” heavy rain; the centroid height of the strong echoes was lower, so it was a kind of mixed precipitation dominated by cumulus clouds, but the mesoscale convective system moved quickly in the highlevel north winds during the “17.07” heavy rain, and the centroid height of the strong echoes was higher, so it belongs to cumulus precipitation. (3) There was a good correlation between the heavy precipitation and the mesoscale convergence line: the ground convergence line provided the enough dynamically lifted condition for the heavy precipitation; both heavy precipitation events happened along with the generation of the convergence line and moved around the convergence line.
By using the ground and upperair observational data, Doppler radar data, FY2E satellite observational data and ERAInterim reanalysis data, the environmental conditions, mesoscale convective systems, the characteristics of Doppler radar reflectivity, the dynamiclifted condition, and forecasting hints are analyzed and compared between two warmsector heavy rain processes occurred on 17 Aug 2012 and 16 July 2017 in the Western Sichuan basin. The results show: (1) Both processes happened under the background of lowlevel warmmoist flows and ground thermal lows; the “12.08” heavy rain occurred on the edge of the subtropical high pressure system; the moisture transport condition was better; and the heavy rainfall maintained longer. The “17.07” heavy rain happened behind the upper vortexshear, the upper cold advection was more obvious, convective unstable energy was more abundant, and the convective system developed stronger. (2) The mesoscale convective system moved slowly on the edge of the subtropicalhigh pressure and had obvious traineffect during the “12.08” heavy rain; the centroid height of the strong echoes was lower, so it was a kind of mixed precipitation dominated by cumulus clouds, but the mesoscale convective system moved quickly in the highlevel north winds during the “17.07” heavy rain, and the centroid height of the strong echoes was higher, so it belongs to cumulus precipitation. (3) There was a good correlation between the heavy precipitation and the mesoscale convergence line: the ground convergence line provided the enough dynamically lifted condition for the heavy precipitation; both heavy precipitation events happened along with the generation of the convergence line and moved around the convergence line.
2019, 47(5):809-817.
Abstract:
Based on the conventional observational data，the observational PM2.5 concentration and NCEP reanalysis data, a comparative analysis is conducted on the atmospheric conditions, boundary layer characteristics of two serious air pollution events which took place in 2013 and 2016,respectively. The results are: (1) At 500 hPa, the processes of 2013 and 2016 were controlled by the blocking circulation and zonal circulation, respectively. The Guanzhong area was affected by the westerly flow; the surface pressure field was weak, and the atmospheric stratification was relatively stable. (2) In the 2013 event, the inversion layer near the ground in Xi’an was low; the relative humidity was high; the temperature was low; which is not conducive to the vertical turbulence exchange and in which the pollutants were easy to accumulate. It is one of the reasons that the process of 2013 heavy pollution lasted longer and the concentration of pollutants was higher than that of 2016. (3) Both heavy pollution processes in Xi’an had the significant low wind speed characteristic, and the northeast wind was the dominant wind direction. The 2013 process is the result of the combination of local pollution accumulation and upstream pollution transmission. (4) The process of 2013 was affected by cold air, and the continuous dry and cold northeast wind made haze dissipate in the Guanzhong area; while the process of 2016 was affected by the plateau trough, and rain and snow weather made pollutants deposite and haze dissipate.
Based on the conventional observational data，the observational PM2.5 concentration and NCEP reanalysis data, a comparative analysis is conducted on the atmospheric conditions, boundary layer characteristics of two serious air pollution events which took place in 2013 and 2016,respectively. The results are: (1) At 500 hPa, the processes of 2013 and 2016 were controlled by the blocking circulation and zonal circulation, respectively. The Guanzhong area was affected by the westerly flow; the surface pressure field was weak, and the atmospheric stratification was relatively stable. (2) In the 2013 event, the inversion layer near the ground in Xi’an was low; the relative humidity was high; the temperature was low; which is not conducive to the vertical turbulence exchange and in which the pollutants were easy to accumulate. It is one of the reasons that the process of 2013 heavy pollution lasted longer and the concentration of pollutants was higher than that of 2016. (3) Both heavy pollution processes in Xi’an had the significant low wind speed characteristic, and the northeast wind was the dominant wind direction. The 2013 process is the result of the combination of local pollution accumulation and upstream pollution transmission. (4) The process of 2013 was affected by cold air, and the continuous dry and cold northeast wind made haze dissipate in the Guanzhong area; while the process of 2016 was affected by the plateau trough, and rain and snow weather made pollutants deposite and haze dissipate.
2019, 47(5):818-829.
Abstract:
Based on the conventional meteorological observation data and ECMWF reanalysis data, two cyclone heavy rain processes in 26 and 27 May 2013 (Process 0526) and 10 and 11 May 2014 (Process 0510) in Qingdao are analyzed. The results indicate that in Process 0526, the relative humidity at 850 hPa before the heavy rain was higher and the duration of rainfall was longer, and in Process 0510, the relative humidity at 850 hPa before the heavy rain was lower and the duration of rainfall was shorter, but stronger. The main causes of longer duration and the larger accumulated of Process 0526 was the better lowlevel wind speed and relative humidity conditions and longlasting upward motion, as well as continuous water vapor transport. In the process of Process 0510, the ground convergence line was a key factor in triggering the shorttime extreme heavy rainfall, and the stronger upward motion was favorable for the short time extreme heavy rainfall.
Based on the conventional meteorological observation data and ECMWF reanalysis data, two cyclone heavy rain processes in 26 and 27 May 2013 (Process 0526) and 10 and 11 May 2014 (Process 0510) in Qingdao are analyzed. The results indicate that in Process 0526, the relative humidity at 850 hPa before the heavy rain was higher and the duration of rainfall was longer, and in Process 0510, the relative humidity at 850 hPa before the heavy rain was lower and the duration of rainfall was shorter, but stronger. The main causes of longer duration and the larger accumulated of Process 0526 was the better lowlevel wind speed and relative humidity conditions and longlasting upward motion, as well as continuous water vapor transport. In the process of Process 0510, the ground convergence line was a key factor in triggering the shorttime extreme heavy rainfall, and the stronger upward motion was favorable for the short time extreme heavy rainfall.
2019, 47(5):830-840.
Abstract:
Based on the conventional observation data, intensive automatic weather station observations, DopplerRadar data, the global final (FNL) analysis, etc., the spatial temporal characteristics, mechanisms and extremes of the extremely intensive precipitation from 15 to 18 July 2018 over the Beijing area are analyzed. The results show that there were three distinct precipitation “wave peaks” in this process. It was a typical warmarea rainfall in North China with the characteristics of long duration, great rainfall and wide coverage. (1) The extreme precipitation had a typical rainstorm circulation situation in North China: with highlevel divergence, around the edge of the subtropical high in the middlelevel, the slowly eastward moving front end of a trough, the lowlevel shear convergence of jet streams, and high temperature and humidity conditions. (2) There were abnormal circulation and physical conditions during the rainstorm process: the abnormally northerly subtropical high, the abnormally strong lowlevel southerly wind, and the extreme energy and water vapor conditions at the upstream of the rainstorm area and abnormally northerly ITCZ (InterTropical Convergence Zone). (3) There was a certain convective potential in this area, which was combined with the intense temperature and humidity transport of the southwest airflow at the middle and lower levels, and its forced uplift in the front of the mountains, and generated a convergence line with the night mountain wind to trigger the convection. The “train effect” and backward propagation of radar echoes were obvious in this process, and the echoes had the characteristics of tropical precipitation echoes with a low centroid.
Based on the conventional observation data, intensive automatic weather station observations, DopplerRadar data, the global final (FNL) analysis, etc., the spatial temporal characteristics, mechanisms and extremes of the extremely intensive precipitation from 15 to 18 July 2018 over the Beijing area are analyzed. The results show that there were three distinct precipitation “wave peaks” in this process. It was a typical warmarea rainfall in North China with the characteristics of long duration, great rainfall and wide coverage. (1) The extreme precipitation had a typical rainstorm circulation situation in North China: with highlevel divergence, around the edge of the subtropical high in the middlelevel, the slowly eastward moving front end of a trough, the lowlevel shear convergence of jet streams, and high temperature and humidity conditions. (2) There were abnormal circulation and physical conditions during the rainstorm process: the abnormally northerly subtropical high, the abnormally strong lowlevel southerly wind, and the extreme energy and water vapor conditions at the upstream of the rainstorm area and abnormally northerly ITCZ (InterTropical Convergence Zone). (3) There was a certain convective potential in this area, which was combined with the intense temperature and humidity transport of the southwest airflow at the middle and lower levels, and its forced uplift in the front of the mountains, and generated a convergence line with the night mountain wind to trigger the convection. The “train effect” and backward propagation of radar echoes were obvious in this process, and the echoes had the characteristics of tropical precipitation echoes with a low centroid.
2019, 47(5):841-850.
Abstract:
Based on the routine observation, NCEP/NCAR reanalysis data and simulation data, a squall line occurred over the coast of Fujian on 20 June 2014 is analyzed. Results show: (1) This squall line was belonged to the pretrough type, and there was a developing low vortex shear in the lowlevel of the troposphere, with a weak cold air going southward. The lowaltitude southwest jet was not obvious, but there was continuous warm and humid air flow delivered to the northern central area of Fujian. The squall line was formed on the south side of the low vortex. (2) The simulation results show that during the development of the squall line, the lowlevel wind speed on the south side of the system increased continuously and maintained high water vapor transport and unstable energy. At the early stage, the triggering factors of the convection include the cold outflow of the frontsystem, the elevation of the terrain, and the forced uplift of the cold pile caused by sea breeze. At the later stage, the collision between the cold outflow boundary and the sea breeze front boundary strengthened the lowlevel convergence and promoted the development of convection, which was the main reason for the formation of the squall line. (3) The pressure field of the squall line appeared to be a meso high and a wake low in its mature stage. A surface divergence zone slightly lagged the meso high where there was strong surface winds. There were two airflows in the squall line at its mature stage. The forward inflow which was lifted in the convective cloud area was a lowlevel warm and humid airflow in front of the squall line. The rear inflow was a middlelayer dry and cold airflow behind the squall line, forming a sinking motion in the lower layer, which was one of the important reasons for the formation of strong winds on the ground.
Based on the routine observation, NCEP/NCAR reanalysis data and simulation data, a squall line occurred over the coast of Fujian on 20 June 2014 is analyzed. Results show: (1) This squall line was belonged to the pretrough type, and there was a developing low vortex shear in the lowlevel of the troposphere, with a weak cold air going southward. The lowaltitude southwest jet was not obvious, but there was continuous warm and humid air flow delivered to the northern central area of Fujian. The squall line was formed on the south side of the low vortex. (2) The simulation results show that during the development of the squall line, the lowlevel wind speed on the south side of the system increased continuously and maintained high water vapor transport and unstable energy. At the early stage, the triggering factors of the convection include the cold outflow of the frontsystem, the elevation of the terrain, and the forced uplift of the cold pile caused by sea breeze. At the later stage, the collision between the cold outflow boundary and the sea breeze front boundary strengthened the lowlevel convergence and promoted the development of convection, which was the main reason for the formation of the squall line. (3) The pressure field of the squall line appeared to be a meso high and a wake low in its mature stage. A surface divergence zone slightly lagged the meso high where there was strong surface winds. There were two airflows in the squall line at its mature stage. The forward inflow which was lifted in the convective cloud area was a lowlevel warm and humid airflow in front of the squall line. The rear inflow was a middlelayer dry and cold airflow behind the squall line, forming a sinking motion in the lower layer, which was one of the important reasons for the formation of strong winds on the ground.
2019, 47(5):851-858.
Abstract:
A severe convection process on 18 May 2018 is studied by the conventional observation data, GFS analysis field data with the spatial resolution of 0.25°×0.25° and temporal resolution of 6 hours, automatic weather station data, and SB Doppler radar data in the middle part of Zhejiang Province. It is demonstrated that this process triggered three types of storms: pulse storm, multicell storms and squall line. These storms were accompanied by the hail shortterm heavy rain, thunderstorm and gale, respectively. The corresponding characteristics of the radar echoes of three storms are as follows: (1) The radar echoes of the pulse storm were in lumpy pieces. The initial height was 6 to 9 km and the heights of strong echoes were around the isotherm of -10 ℃. The strong intensity was up to 60 dBz. The VIL value increased rapidly and the maximum value was 50 kg·m-2. The small hail and gale appeared after the rapid decrease of reflectivity and VIL. (2) The mediumtostrong multicell storms were in a beltlike distribution. The train effect and high precipitation efficiency were responsible for the wide range heavy precipitation. The gale was in relation to MARC (MidAltitude Radial Convergence) of the velocity product and strong convergence. (3) The squall line appeared to be a bow echo. It moved with high speed and caused the extreme gale and thunderstorm. This multistorm severe convective process is of important significance for shortterm weather forecasting in the future.
A severe convection process on 18 May 2018 is studied by the conventional observation data, GFS analysis field data with the spatial resolution of 0.25°×0.25° and temporal resolution of 6 hours, automatic weather station data, and SB Doppler radar data in the middle part of Zhejiang Province. It is demonstrated that this process triggered three types of storms: pulse storm, multicell storms and squall line. These storms were accompanied by the hail shortterm heavy rain, thunderstorm and gale, respectively. The corresponding characteristics of the radar echoes of three storms are as follows: (1) The radar echoes of the pulse storm were in lumpy pieces. The initial height was 6 to 9 km and the heights of strong echoes were around the isotherm of -10 ℃. The strong intensity was up to 60 dBz. The VIL value increased rapidly and the maximum value was 50 kg·m-2. The small hail and gale appeared after the rapid decrease of reflectivity and VIL. (2) The mediumtostrong multicell storms were in a beltlike distribution. The train effect and high precipitation efficiency were responsible for the wide range heavy precipitation. The gale was in relation to MARC (MidAltitude Radial Convergence) of the velocity product and strong convergence. (3) The squall line appeared to be a bow echo. It moved with high speed and caused the extreme gale and thunderstorm. This multistorm severe convective process is of important significance for shortterm weather forecasting in the future.
2019, 47(5):859-865.
Abstract:
In this paper, the spatial distribution and diurnal variation characteristics of 34 rainstorms in Chongqing are analyzed based on the precipitation data from 1981 to 2017 and the hourly precipitation data from 2005 to 2017 from 34 ground observation stations in Chongqing. The results demonstrate that Kaizhou, Youyang and Beibei were the rainstorm centers of Chongqing. The annual average rainstorm days in Kaizhou were up to 6.2 days. In Rongchang, Yubei, Liangping, Kaizhou, Pengshui and Youyang, the frequency of rainstorms was relatively high, while that was relatively low in Nanchuan, and Wansheng. Large average precipitation amount during rainstorm days was found in the main urban area, the western area and the northeast area, while the average precipitation amount in the southwest area was smaller. Rainstorms in Chongqing affected different main areas in different periods. Nighttime precipitation in Tongliang, Hechuan and Beibei during rainstorm days accounted for more than 75%. In the representative stations, the average rainfall intensity in the nighttime was higher than that in the daytime. The precipitation in Dazu, Shapingba and Fuling mainly concentrated in the period from 22:00 to the next 04:00, and the rainfall intensity in Youyang was higher from 03:00 to 06:00. The frequency of hourly precipitation of over 20 mm in rainstorm days was higher from 00:00 to 06:00 and from 13:00 to 18:00.
In this paper, the spatial distribution and diurnal variation characteristics of 34 rainstorms in Chongqing are analyzed based on the precipitation data from 1981 to 2017 and the hourly precipitation data from 2005 to 2017 from 34 ground observation stations in Chongqing. The results demonstrate that Kaizhou, Youyang and Beibei were the rainstorm centers of Chongqing. The annual average rainstorm days in Kaizhou were up to 6.2 days. In Rongchang, Yubei, Liangping, Kaizhou, Pengshui and Youyang, the frequency of rainstorms was relatively high, while that was relatively low in Nanchuan, and Wansheng. Large average precipitation amount during rainstorm days was found in the main urban area, the western area and the northeast area, while the average precipitation amount in the southwest area was smaller. Rainstorms in Chongqing affected different main areas in different periods. Nighttime precipitation in Tongliang, Hechuan and Beibei during rainstorm days accounted for more than 75%. In the representative stations, the average rainfall intensity in the nighttime was higher than that in the daytime. The precipitation in Dazu, Shapingba and Fuling mainly concentrated in the period from 22:00 to the next 04:00, and the rainfall intensity in Youyang was higher from 03:00 to 06:00. The frequency of hourly precipitation of over 20 mm in rainstorm days was higher from 00:00 to 06:00 and from 13:00 to 18:00.
2019, 47(5):866-871.
Abstract:
Based on the high temporalspatial resolution visibility data from 2011 to 2016, the spatial distribution characteristics of visibility and its variation in the fog formation process are analyzed. Results show: the ratio of the normal distribution or lognormal distribution in visibility spatial distribution was more than 95%. The ratio decreased significantly while there were fogs; the coefficient of variation formed a peak structure in fog formation process; the highdensity visibility data was used to make nowcasting or early warning of heavy fogs and the time was 1.9 hours ahead of the warning time averagely.
Based on the high temporalspatial resolution visibility data from 2011 to 2016, the spatial distribution characteristics of visibility and its variation in the fog formation process are analyzed. Results show: the ratio of the normal distribution or lognormal distribution in visibility spatial distribution was more than 95%. The ratio decreased significantly while there were fogs; the coefficient of variation formed a peak structure in fog formation process; the highdensity visibility data was used to make nowcasting or early warning of heavy fogs and the time was 1.9 hours ahead of the warning time averagely.
2019, 47(5):872-878.
Abstract:
The actual observation photos of Yali pear flower bud development from 2012 to 2018 are used to accurately determine the occurrence time of each node of Yali pear flower bud development phenological period. Based on this data, the meteorological factors in each phenological phase in Yali pear bud development are studied. The effects of meteorological influencing factors on flower bud development are analyzed according to the phenological phases. The result shows that the temperature plays a leading role in the development of the flower buds of Yali pear, and three prediction indexes, i.e., the average daily temperature, ≥0 °C active accumulated temperature, and ≥3 °C effective accumulation temperature in the periods from germination to first flowering, sprouting to first flowering, squaring to first flowering, are selected to determine the Yali pear flowering dates. According to the application test from 2016 to 2018, the prediction error between the predicted results and the actual flowering of Yali pear is within 1 to 2 days when the prediction time is 10 to 12 days, and the predicted results are completely consistent with the actual flowering of Yali pear when the prediction time is 7 days. This study overcomes the shortcomings of traditional plant flowering forecasting, such as the lack of phenological data before flowering and the inability of the preflowering period analysis, and introduces the medium and longterm weather forecasting products into flowering forecasting, which provides a new idea for flowering forecasting.
The actual observation photos of Yali pear flower bud development from 2012 to 2018 are used to accurately determine the occurrence time of each node of Yali pear flower bud development phenological period. Based on this data, the meteorological factors in each phenological phase in Yali pear bud development are studied. The effects of meteorological influencing factors on flower bud development are analyzed according to the phenological phases. The result shows that the temperature plays a leading role in the development of the flower buds of Yali pear, and three prediction indexes, i.e., the average daily temperature, ≥0 °C active accumulated temperature, and ≥3 °C effective accumulation temperature in the periods from germination to first flowering, sprouting to first flowering, squaring to first flowering, are selected to determine the Yali pear flowering dates. According to the application test from 2016 to 2018, the prediction error between the predicted results and the actual flowering of Yali pear is within 1 to 2 days when the prediction time is 10 to 12 days, and the predicted results are completely consistent with the actual flowering of Yali pear when the prediction time is 7 days. This study overcomes the shortcomings of traditional plant flowering forecasting, such as the lack of phenological data before flowering and the inability of the preflowering period analysis, and introduces the medium and longterm weather forecasting products into flowering forecasting, which provides a new idea for flowering forecasting.
2019, 47(5):879-884.
Abstract:
Aiming at solving the problem of wind disaster information acquisition in Guangzhou, Guangdong Province, this study established an application model based on the characteristic analysis of location microblogs. The acquisition model has such functions as semantic retrieval and filtering analysis, disaster information classification and mapping, disaster situation weighting and GIS hotspot analysis. The model was applied to extract the wind information in Guangzhou, during the strong convection weather in 21 April 2017. The result shows that the wind information acquisition model has a certain practical value for wind information acquisition problems. Compared with the conventional method of wind information acquisition, the location microblog data was more rapid, low cost and abundant. This model provides a new method for wind disaster information extraction.
Aiming at solving the problem of wind disaster information acquisition in Guangzhou, Guangdong Province, this study established an application model based on the characteristic analysis of location microblogs. The acquisition model has such functions as semantic retrieval and filtering analysis, disaster information classification and mapping, disaster situation weighting and GIS hotspot analysis. The model was applied to extract the wind information in Guangzhou, during the strong convection weather in 21 April 2017. The result shows that the wind information acquisition model has a certain practical value for wind information acquisition problems. Compared with the conventional method of wind information acquisition, the location microblog data was more rapid, low cost and abundant. This model provides a new method for wind disaster information extraction.
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.