Volume 48,Issue 3,2020 Table of Contents
2020, 48(3):313-321.
Abstract:
In order to accurately retrieve the microphysical parameters of snowflake particles using radar, the exponential distribution of nonspherical snow particle swarm is established and the backscattering crosssections of nonspherical snow particle swarm at six different incident directions are calculated at 94 GHz using the XFDTD software and then compared with the results of simple addition. For the same incident directions, all the backscattering crosssection results of the particle swarm are larger than the result of simple addition. For the different incident directions, the backscattering crosssection results of the particle swarm are different. These results show that the direction of multiple scattering and incident electromagnetic wave must be considered in the actual radar detection.
In order to accurately retrieve the microphysical parameters of snowflake particles using radar, the exponential distribution of nonspherical snow particle swarm is established and the backscattering crosssections of nonspherical snow particle swarm at six different incident directions are calculated at 94 GHz using the XFDTD software and then compared with the results of simple addition. For the same incident directions, all the backscattering crosssection results of the particle swarm are larger than the result of simple addition. For the different incident directions, the backscattering crosssection results of the particle swarm are different. These results show that the direction of multiple scattering and incident electromagnetic wave must be considered in the actual radar detection.
2020, 48(3):322-330.
Abstract:
In order to detect and evaluate the echo differences of different bands, models and regions of the national weather radar and to ensure the homogeneity of radar networking data, a reliable detection algorithm for the homogeneity of adjacent radar echo intensity is established by using the CAPPI lattice data of singlestation radar after strict data quality control. According to the actual situation of weather radar echo difference in China, the uniformity evaluation criteria are formulated and the operational running of homogeneity algorithms is realized, which makes it possible to evaluate the realtime uniformity of radar echo reflectivity in the same area. From the evaluation results, the overall homogeneity of Sband radar is stronger than that of Cband radar. The SA radar has the best homogeneity, while the CC and the CD radar have the worse homogeneity. The eastern and southern China, where SA radar is used widely, have better homogeneity. The radar bands are different and the homogeneity of remote areas with various models is poor. The homogeneity evaluation system is applied to the case of having echo intensity, but with incorrect echo location and time misalignment of radar echoes. It can effectively compensate for the shortcomings of other quality control algorithms. It can find abnormal radar echoes in time, shorten the repair time and improve the accuracy of radar data.
In order to detect and evaluate the echo differences of different bands, models and regions of the national weather radar and to ensure the homogeneity of radar networking data, a reliable detection algorithm for the homogeneity of adjacent radar echo intensity is established by using the CAPPI lattice data of singlestation radar after strict data quality control. According to the actual situation of weather radar echo difference in China, the uniformity evaluation criteria are formulated and the operational running of homogeneity algorithms is realized, which makes it possible to evaluate the realtime uniformity of radar echo reflectivity in the same area. From the evaluation results, the overall homogeneity of Sband radar is stronger than that of Cband radar. The SA radar has the best homogeneity, while the CC and the CD radar have the worse homogeneity. The eastern and southern China, where SA radar is used widely, have better homogeneity. The radar bands are different and the homogeneity of remote areas with various models is poor. The homogeneity evaluation system is applied to the case of having echo intensity, but with incorrect echo location and time misalignment of radar echoes. It can effectively compensate for the shortcomings of other quality control algorithms. It can find abnormal radar echoes in time, shorten the repair time and improve the accuracy of radar data.
2020, 48(3):331-336.
Abstract:
The new generation of dualpolarized weather radar plays an important role in the monitoring and early warning of severe weather such as heavy rainall and typhoons. With the development of meteorological modernization and the increasing requirements for timeliness and refinement, the Sband new generation dualpolarization weather radar cannot fully meet the needs of rapid development of researches and the early warning of small and mediumscale weather systems. The spacetime resolution of meteorological radar plays an important role in detecting smallscale structures in strong convection. Improving the temporal and spatial resolution of weather radar is the key to refined detection technology. This paper focuses on the temporal and spatial resolution of the new generation weather radar and the antenna sweeping method so as to improve the weather radar pulse repetition frequency, signal processing and scanning methods, to improve the capability of a new generation dualpolarized weather radar to detect catastrophic weather such as small and mediumsized cyclones and tornadoes and to get more accurate observations with faster refinement of weather processes.
The new generation of dualpolarized weather radar plays an important role in the monitoring and early warning of severe weather such as heavy rainall and typhoons. With the development of meteorological modernization and the increasing requirements for timeliness and refinement, the Sband new generation dualpolarization weather radar cannot fully meet the needs of rapid development of researches and the early warning of small and mediumscale weather systems. The spacetime resolution of meteorological radar plays an important role in detecting smallscale structures in strong convection. Improving the temporal and spatial resolution of weather radar is the key to refined detection technology. This paper focuses on the temporal and spatial resolution of the new generation weather radar and the antenna sweeping method so as to improve the weather radar pulse repetition frequency, signal processing and scanning methods, to improve the capability of a new generation dualpolarized weather radar to detect catastrophic weather such as small and mediumsized cyclones and tornadoes and to get more accurate observations with faster refinement of weather processes.
2020, 48(3):337-341.
Abstract:
This paper studies the period verification method for the PG7601 gas piston gauges, and elaborates the period verification method from the aspects of selecting the verification standards, determining the verification parameters, processing the verification data and analyzing the verification results. Unlike a single verification of pressure value， this method not only checks whether the pressure value is accurate and reliable, but also checks the working state of PG7601 more effectively and accurately by checking the effective area of the piston. The absolute value of the pressure error of PG7601 at each gas pressure test point is calculated and compared with the square and root of the expanded uncertainty of the two piston pressure gauges at the corresponding points. This period verification method provides a more scientific and effective way to check the working state of gas piston gauges.
This paper studies the period verification method for the PG7601 gas piston gauges, and elaborates the period verification method from the aspects of selecting the verification standards, determining the verification parameters, processing the verification data and analyzing the verification results. Unlike a single verification of pressure value， this method not only checks whether the pressure value is accurate and reliable, but also checks the working state of PG7601 more effectively and accurately by checking the effective area of the piston. The absolute value of the pressure error of PG7601 at each gas pressure test point is calculated and compared with the square and root of the expanded uncertainty of the two piston pressure gauges at the corresponding points. This period verification method provides a more scientific and effective way to check the working state of gas piston gauges.
2020, 48(3):342-347.
Abstract:
Meteorological station metadata contains important information that may affect the homogeneity of climate data series and is a scientific reference for analysis, testing, and revision of climate data series. Only the metadata of meteorological stations after quality control and processing can truly reflect the degree of influence on the heterogeneity of climate data series. In this paper, a set of quality control techniques for the metadata of meteorological stations is designed based on the basic idea of traditional quality control method, the methods of limit value inspection, internal consistency inspection and time continuity inspection are used for quality control. The quality control method is used to control the historical data files of 1428 stations in 31 provinces (region, cities) of China from 1951 to 2011. The results show that the quality control program can effectively mark the error information. It can provide reliable quality assurance for the application of metadata of meteorological stations. The quality control method has been applied in the meteorological data service system (MDOS) and in provincial meteorological data departments nationwide.
Meteorological station metadata contains important information that may affect the homogeneity of climate data series and is a scientific reference for analysis, testing, and revision of climate data series. Only the metadata of meteorological stations after quality control and processing can truly reflect the degree of influence on the heterogeneity of climate data series. In this paper, a set of quality control techniques for the metadata of meteorological stations is designed based on the basic idea of traditional quality control method, the methods of limit value inspection, internal consistency inspection and time continuity inspection are used for quality control. The quality control method is used to control the historical data files of 1428 stations in 31 provinces (region, cities) of China from 1951 to 2011. The results show that the quality control program can effectively mark the error information. It can provide reliable quality assurance for the application of metadata of meteorological stations. The quality control method has been applied in the meteorological data service system (MDOS) and in provincial meteorological data departments nationwide.
2020, 48(3):348-354.
Abstract:
In order to meet the requirement of the integrative and refined monitoring of the various climate operational systems of the National Climate Center, the operation monitoring platform of the climate operational systems is designed and implemented. The platform presents the monitoring results of data and product integrity, database status, key processes, data access, server basic resources and other aspects of the climate operational systems in a multidimensional way, and has the functions of fault warning, system management, data push and display. This paper introduces the operating architecture, main functions of the platform, and describes key technologies in detail. The practices of climate operation have proved that the platform can help the personnel master the state of each climate operational system timely, quickly and comprehensively, improve the efficiency of operation and maintenance, and is conducive to the promotion of the integrative and intensive development of climate operation.
In order to meet the requirement of the integrative and refined monitoring of the various climate operational systems of the National Climate Center, the operation monitoring platform of the climate operational systems is designed and implemented. The platform presents the monitoring results of data and product integrity, database status, key processes, data access, server basic resources and other aspects of the climate operational systems in a multidimensional way, and has the functions of fault warning, system management, data push and display. This paper introduces the operating architecture, main functions of the platform, and describes key technologies in detail. The practices of climate operation have proved that the platform can help the personnel master the state of each climate operational system timely, quickly and comprehensively, improve the efficiency of operation and maintenance, and is conducive to the promotion of the integrative and intensive development of climate operation.
2020, 48(3):355-361.
Abstract:
In order to give full play to the role of lightning data and solve the quality problem of data, the lightning comprehensive database and data analysis and processing platform are established. Based on the WebGIS JavaScript framework and CIMISS database, the lightning data analysis and processing system with the data processing, quality control, and analysis functions is designed and developed and the lightning information database is set up by lightning, atmospheric electric field, thunderstorm and lightning disaster data (as the main content). The system can monitor in real time the various detection information of atmospheric electric fields, such as satellite, radar and lightning, to carry out the lightning data quality control, playback and dynamically display of the history information, conducting the information query statistics, analysis, and curve plotting, and having multiple functions such as thunder and lightning report making, so to provide a convenient and efficient application and technology platform for lightning protection research and service. A strong lightning weather process on 1 and 2 June 2015 in Jianli, Hubei is taken as an example to analyze the lightning process. The results show that the thunder and lightning monitoring data analysis and processing system can meet the needs of the lightning protection service and scientific researches, which can monitor thunders and lightning accurately, make various charts and statistical analysis results quickly, and provide an efficient basic platform for lightning disaster prevention and service.
In order to give full play to the role of lightning data and solve the quality problem of data, the lightning comprehensive database and data analysis and processing platform are established. Based on the WebGIS JavaScript framework and CIMISS database, the lightning data analysis and processing system with the data processing, quality control, and analysis functions is designed and developed and the lightning information database is set up by lightning, atmospheric electric field, thunderstorm and lightning disaster data (as the main content). The system can monitor in real time the various detection information of atmospheric electric fields, such as satellite, radar and lightning, to carry out the lightning data quality control, playback and dynamically display of the history information, conducting the information query statistics, analysis, and curve plotting, and having multiple functions such as thunder and lightning report making, so to provide a convenient and efficient application and technology platform for lightning protection research and service. A strong lightning weather process on 1 and 2 June 2015 in Jianli, Hubei is taken as an example to analyze the lightning process. The results show that the thunder and lightning monitoring data analysis and processing system can meet the needs of the lightning protection service and scientific researches, which can monitor thunders and lightning accurately, make various charts and statistical analysis results quickly, and provide an efficient basic platform for lightning disaster prevention and service.
2020, 48(3):362-367.
Abstract:
Based on the workflow engine technology associated with serviceoriented architecture (SOA), this paper explores a task scheduling architecture for weather and climate management operation, which meets the needs of flexible and convenient scheduling and control of operation nodes, processes and scenarios. Through the integrated management and control of the nodecentered function algorithm, the component registration and resource reuse functions of the process nodes are realized. Through the configurable process assembly mode, weather and climate management can be changed quickly by service choreography. By the capability of visual process choreography, it is possible to monitor the processing of various processes accurately and conveniently. After the trial operation of this architecture which has been put into operation, the realtime operation requirements can be satisfied.
Based on the workflow engine technology associated with serviceoriented architecture (SOA), this paper explores a task scheduling architecture for weather and climate management operation, which meets the needs of flexible and convenient scheduling and control of operation nodes, processes and scenarios. Through the integrated management and control of the nodecentered function algorithm, the component registration and resource reuse functions of the process nodes are realized. Through the configurable process assembly mode, weather and climate management can be changed quickly by service choreography. By the capability of visual process choreography, it is possible to monitor the processing of various processes accurately and conveniently. After the trial operation of this architecture which has been put into operation, the realtime operation requirements can be satisfied.
2020, 48(3):368-373.
Abstract:
Using the UDP multicast communication, process monitoring, file monitoring, network monitoring and other technologies, the stationlevel monitoring and alarm system for CC weather radar data stream transmission service is developed. The realtime monitoring and short message alarm of radar scanning status, data stream upstream transmission, standard format base data local storage, base data replenishment, software operation and network operation status are implemented. Practice shows that the software runs stably, can effectively monitor the data flow transmission, and the short message alarm is accurate and timely. The alarm threshold is reduced from 6 minutes to 40 seconds, which improves the efficiency of fault detection and processing, the operational availability of weather radar, and the quality of data transmission, and reduced the duty pressure of radar station operators.
Using the UDP multicast communication, process monitoring, file monitoring, network monitoring and other technologies, the stationlevel monitoring and alarm system for CC weather radar data stream transmission service is developed. The realtime monitoring and short message alarm of radar scanning status, data stream upstream transmission, standard format base data local storage, base data replenishment, software operation and network operation status are implemented. Practice shows that the software runs stably, can effectively monitor the data flow transmission, and the short message alarm is accurate and timely. The alarm threshold is reduced from 6 minutes to 40 seconds, which improves the efficiency of fault detection and processing, the operational availability of weather radar, and the quality of data transmission, and reduced the duty pressure of radar station operators.
2020, 48(3):374-379.
Abstract:
Using the Python language, the decoding and visualization of the new generation Doppler weather radar storm data is realized. Through the establishment of the storm automatic matching method and in use of Python geographic information visualization and time series visualization technology, the animation display effect of storm tracking is achieved. By using Python data analysis and chart visualization technology, the multidimensional information of the storm can be displayed in the chart, and the trend of the storm can be intuitively displayed. The work in this paper provides a more general method to get the storm information quickly, which brings convenience to weather forecasters to use the radar data. Meanwhile, the enhanced visualization of storm information improves the reuse of data and supports the researches in the field of expertise.
Using the Python language, the decoding and visualization of the new generation Doppler weather radar storm data is realized. Through the establishment of the storm automatic matching method and in use of Python geographic information visualization and time series visualization technology, the animation display effect of storm tracking is achieved. By using Python data analysis and chart visualization technology, the multidimensional information of the storm can be displayed in the chart, and the trend of the storm can be intuitively displayed. The work in this paper provides a more general method to get the storm information quickly, which brings convenience to weather forecasters to use the radar data. Meanwhile, the enhanced visualization of storm information improves the reuse of data and supports the researches in the field of expertise.
2020, 48(3):380-386.
Abstract:
Characteristics and variation trends of acid rainfall in Chengdu are analyzed using the historical observation data of acid rains combined with the concentrations of air pollutants and other surface meteorological data such as precipitation amount and winds at Wenjiang and Jianyang stations from 2006 to 2017. Results show that the average pH of precipitation and the frequency of acid rains were 4.74 and 51.6% at Wenjiang, respectively, while the corresponding values were 5.64 and 27.2% at Jianyang, implying that the frequency of acid rains was not distributed uniformly across the geographical area. Seasonal variations of pH and K values of precipitation were significant, with high pH values in summer and low in winter. In contrast, the high K values were observed in winter and low values in summer. The annual variation trends of pH of precipitation increased during the observation periods, corresponding to the decreasing trends of frequency and intensity of acid rains. In addition, the K values decreased dramatically, with a decrease rate of 3.5 and 3.7 μS〖DK〗·cm-1〖DK〗·a-1 at Wenjiang and Jianyang, respectively. The pH of precipitation showed negative correlations with SO2 and NO2 with a correlation coefficient of -0.488, and sulfur oxides contributed less to acid rain pollution; while K values exhibited highly positive correlations with the above pollutants with a correlation coefficient of 0.657. The relationship between pH and K values for SO2 and NO2 were stronger than that of PM10 and PM2.5. Additionally, the concentrations of atmospheric particulate had an significant impact on the K values. The pH varied insignificantly with precipitation amount, while K values decreased with the increase of precipitation amount. Winds showed a positive correlation with pH but negative correlation with K values of precipitation.
Characteristics and variation trends of acid rainfall in Chengdu are analyzed using the historical observation data of acid rains combined with the concentrations of air pollutants and other surface meteorological data such as precipitation amount and winds at Wenjiang and Jianyang stations from 2006 to 2017. Results show that the average pH of precipitation and the frequency of acid rains were 4.74 and 51.6% at Wenjiang, respectively, while the corresponding values were 5.64 and 27.2% at Jianyang, implying that the frequency of acid rains was not distributed uniformly across the geographical area. Seasonal variations of pH and K values of precipitation were significant, with high pH values in summer and low in winter. In contrast, the high K values were observed in winter and low values in summer. The annual variation trends of pH of precipitation increased during the observation periods, corresponding to the decreasing trends of frequency and intensity of acid rains. In addition, the K values decreased dramatically, with a decrease rate of 3.5 and 3.7 μS〖DK〗·cm-1〖DK〗·a-1 at Wenjiang and Jianyang, respectively. The pH of precipitation showed negative correlations with SO2 and NO2 with a correlation coefficient of -0.488, and sulfur oxides contributed less to acid rain pollution; while K values exhibited highly positive correlations with the above pollutants with a correlation coefficient of 0.657. The relationship between pH and K values for SO2 and NO2 were stronger than that of PM10 and PM2.5. Additionally, the concentrations of atmospheric particulate had an significant impact on the K values. The pH varied insignificantly with precipitation amount, while K values decreased with the increase of precipitation amount. Winds showed a positive correlation with pH but negative correlation with K values of precipitation.
2020, 48(3):387-395.
Abstract:
The mesomicroscale systems and radar echo characteristics during 32 shortterm strong rainfall cases in Qingdao from 2011 to 2015 are analyzed based on the CINRAD/SA radar reflectivity factor, automatic raingauge and FNL reanalysis data. The results show that the mesomicroscale systems that led to shortterm strong rainfall are the mesoscale convergence areas or lines related to the lowlevel shear line (trough), inverted typhoon trough or local convections in Southerly (Northerly). The radar echoes mostly show as a mesoscale strong echo band or local strong convective cells, and the angle between moving direction and long axis of the echo band is small, and otherwise the moving speed of local cells is slow. The shortterm strong rainfall can be divided into the continental convection type and tropical marine type by the centroid height of radar reflectivity. The average vertical profile of reflectivity of the continental convection type is generally stronger than that of the tropical marine type, which brings much stronger convective activity. The strongest reflectivity of the tropical marine type occurs in the low level with the maximum near the land surface; however, the continental convection type has clear hanging echoes with the maximum at 2 km altitude. Two different ZI relations corresponding to the two rainfall types are used for quantitative precipitation estimation. Compared with the fixed ZI relation, the result from the categorical relations shows better performance for the displacement and value of shortterm strong rainfall, and the relative error is reduced from 70% to 30% when the rainfall intensity is greater than 20 mm·h-1.
The mesomicroscale systems and radar echo characteristics during 32 shortterm strong rainfall cases in Qingdao from 2011 to 2015 are analyzed based on the CINRAD/SA radar reflectivity factor, automatic raingauge and FNL reanalysis data. The results show that the mesomicroscale systems that led to shortterm strong rainfall are the mesoscale convergence areas or lines related to the lowlevel shear line (trough), inverted typhoon trough or local convections in Southerly (Northerly). The radar echoes mostly show as a mesoscale strong echo band or local strong convective cells, and the angle between moving direction and long axis of the echo band is small, and otherwise the moving speed of local cells is slow. The shortterm strong rainfall can be divided into the continental convection type and tropical marine type by the centroid height of radar reflectivity. The average vertical profile of reflectivity of the continental convection type is generally stronger than that of the tropical marine type, which brings much stronger convective activity. The strongest reflectivity of the tropical marine type occurs in the low level with the maximum near the land surface; however, the continental convection type has clear hanging echoes with the maximum at 2 km altitude. Two different ZI relations corresponding to the two rainfall types are used for quantitative precipitation estimation. Compared with the fixed ZI relation, the result from the categorical relations shows better performance for the displacement and value of shortterm strong rainfall, and the relative error is reduced from 70% to 30% when the rainfall intensity is greater than 20 mm·h-1.
2020, 48(3):396-405.
Abstract:
Based on the NCEP (National Center of Environmental Prediction) reanalysis data with a resolution of 1°×1°, conventional meteorological data and intensive snowfall observations from 2008 to 2018, ten typical weather processes of rainsnow conversion in Hangzhou are selected in the aspects of largescale circulation background and physical quantities such as dynamic, water vapor and thermal factors. Ultimately, the typical winter forecast hints of rainsnow conversion in Hangzhou are concluded as follows: (1) The largescale circulation configuration provides favorable conditions including water vapor, dynamic lifting and inversion or isothermal stratification in the middle and lower troposphere for the formation of rain to snow. 〖JP2〗(2) The physical quantities such as water vapor 〖JP3〗and dynamic factors should satisfy specific conditions for snow. (3) The temperature stratification in Hangzhou should be 〖WTBX〗T〖WTBZ〗2m≤1.5 ℃,〖JP〗 〖WTBX〗T〖WTBZ〗925≤4.0 ℃, 〖WTBX〗T〖WTBZ〗850≤0 ℃, 〖WTBX〗T〖WTBZ〗700≤-1.0 ℃ and 〖WTBX〗T〖WTBZ〗500≤-10.0 ℃. In addition, the possible conditions for heavy snow or even blizzards in Hangzhou are further discussed. Moreover, two typical precipitation processes at the beginning of 2019 are selected for forecast inspection.
Based on the NCEP (National Center of Environmental Prediction) reanalysis data with a resolution of 1°×1°, conventional meteorological data and intensive snowfall observations from 2008 to 2018, ten typical weather processes of rainsnow conversion in Hangzhou are selected in the aspects of largescale circulation background and physical quantities such as dynamic, water vapor and thermal factors. Ultimately, the typical winter forecast hints of rainsnow conversion in Hangzhou are concluded as follows: (1) The largescale circulation configuration provides favorable conditions including water vapor, dynamic lifting and inversion or isothermal stratification in the middle and lower troposphere for the formation of rain to snow. 〖JP2〗(2) The physical quantities such as water vapor 〖JP3〗and dynamic factors should satisfy specific conditions for snow. (3) The temperature stratification in Hangzhou should be 〖WTBX〗T〖WTBZ〗2m≤1.5 ℃,〖JP〗 〖WTBX〗T〖WTBZ〗925≤4.0 ℃, 〖WTBX〗T〖WTBZ〗850≤0 ℃, 〖WTBX〗T〖WTBZ〗700≤-1.0 ℃ and 〖WTBX〗T〖WTBZ〗500≤-10.0 ℃. In addition, the possible conditions for heavy snow or even blizzards in Hangzhou are further discussed. Moreover, two typical precipitation processes at the beginning of 2019 are selected for forecast inspection.
2020, 48(3):406-414.
Abstract:
Based on the data of 33.44 GHz millimeter wave radar detection, combined with weather situation and automatic stations nearby, a sea fog from the night of 27 March to the morning of 28 March 2018 in the Ningbo coast is analyzed. The results show that it was mainly a radiation fog process, having abundant water vapor below 850 hPa, inversion temperature and high ground pressure, which provided favorable conditions for it. The sea fog developed from lower to upper with a maximum echo height of about 230 m and disappeared from top to bottom, and there was a wind convergence and calm zone being beneficial to the sea fog. The disappearance of the sea fog was more than 3 hours later than that on the land. The echo height and intensity both had a trend of double peaks, except for the generation and disappearance stages, and the occurrence time and causes were different. In addition to the generation stage, the reflectivity was inhomogeneous in the horizontal direction, and the lowlevel reflectivity was generally stronger than that of the higher layer. Compared with visibility stations， millimeter wave radar can detect the variation and vertical structure of sea fog more effectively; however, due to the small reflectance, sea fogs could not be detected in some areas.
Based on the data of 33.44 GHz millimeter wave radar detection, combined with weather situation and automatic stations nearby, a sea fog from the night of 27 March to the morning of 28 March 2018 in the Ningbo coast is analyzed. The results show that it was mainly a radiation fog process, having abundant water vapor below 850 hPa, inversion temperature and high ground pressure, which provided favorable conditions for it. The sea fog developed from lower to upper with a maximum echo height of about 230 m and disappeared from top to bottom, and there was a wind convergence and calm zone being beneficial to the sea fog. The disappearance of the sea fog was more than 3 hours later than that on the land. The echo height and intensity both had a trend of double peaks, except for the generation and disappearance stages, and the occurrence time and causes were different. In addition to the generation stage, the reflectivity was inhomogeneous in the horizontal direction, and the lowlevel reflectivity was generally stronger than that of the higher layer. Compared with visibility stations， millimeter wave radar can detect the variation and vertical structure of sea fog more effectively; however, due to the small reflectance, sea fogs could not be detected in some areas.
2020, 48(3):415-420.
Abstract:
Based on the observed data of Typhoon Bebinca from a large meteorological buoy station in the Beibu Gulf, the variation characteristics of wind waves during the transit of the typhoon are analyzed. The results indicate: The time history curve of typhoon wind speed shows a double peak distribution, and the wind speed in the eyewall area of the typhoon was the largest. The wind speeds in the front eyewall area was greater than that in the back eyewall area. The maximum wind speeds in the front eyewall and the back eyewall were 22.6 m/s and 20.8 m/s, respectively. Typhoon eye area had the smallest pressure and wind speed, the largest wave height and wave period. The maximum wind speed in the eye area was 2.7 m/s, the maximum wave height was 5.4 m and the maximum wave period was 5.5 s. The maximum of wave height lagged behind the maximum of wind speed, and the lag time was about 40 minutes. The wave heights outside the eye area of typhoon were positively correlated with wind speed. During the period of typhoon influence when it was through the south of the meteorological buoy station, both wind direction and wave direction rotated clockwise, and wind direction and wave direction 10minute maximum rotated 50° and 150°, respectively. The wind and wave were not in the same direction, and the average angle between them was 171°.
Based on the observed data of Typhoon Bebinca from a large meteorological buoy station in the Beibu Gulf, the variation characteristics of wind waves during the transit of the typhoon are analyzed. The results indicate: The time history curve of typhoon wind speed shows a double peak distribution, and the wind speed in the eyewall area of the typhoon was the largest. The wind speeds in the front eyewall area was greater than that in the back eyewall area. The maximum wind speeds in the front eyewall and the back eyewall were 22.6 m/s and 20.8 m/s, respectively. Typhoon eye area had the smallest pressure and wind speed, the largest wave height and wave period. The maximum wind speed in the eye area was 2.7 m/s, the maximum wave height was 5.4 m and the maximum wave period was 5.5 s. The maximum of wave height lagged behind the maximum of wind speed, and the lag time was about 40 minutes. The wave heights outside the eye area of typhoon were positively correlated with wind speed. During the period of typhoon influence when it was through the south of the meteorological buoy station, both wind direction and wave direction rotated clockwise, and wind direction and wave direction 10minute maximum rotated 50° and 150°, respectively. The wind and wave were not in the same direction, and the average angle between them was 171°.
2020, 48(3):421-427.
Abstract:
Based on the precipitation forecast dataset from the European Centre for MediumRange Weather Forecasts (ECMWF) and the daily accumulated precipitation of 2403 national surface meteorological observation stations across China, the calibration on daily precipitation by means of the categorized rainfall regression and the further calibration by means of the frequencymatching method are conducted. The results show that compared with the bilinear method, the categorized rainfall regression is more effective in decreasing the forecast biases, and improves the correlation coefficient with the observed data and the equitable threat score. The forecasts of different thresholds become more accurate after applying the frequencymatching method, with the smaller area deviation. The false alarm rate of light rain and the missing rate of heavy rain are also both reduced. Improvements of the forecasts by the categorized rainfall regression and the frequencymatching method differ in initialized times, rainfall thresholds and lead times. After the calibration of the categorized rainfall regression, the forecast initialized at 20:00 is improved with a larger magnitude than that at 08:00. The improvement of the forecast is relatively limited for rainfall thresholds of 01 mm and 50 mm, but significant for thresholds of 5 mm, 10 mm and 15 mm. Additionally, the amplitude of the improvement increases slightly over the lead time. The improvement induced by the frequencymatching method is greater for precipitation forecasts initialized at specific times that show worse performances.
Based on the precipitation forecast dataset from the European Centre for MediumRange Weather Forecasts (ECMWF) and the daily accumulated precipitation of 2403 national surface meteorological observation stations across China, the calibration on daily precipitation by means of the categorized rainfall regression and the further calibration by means of the frequencymatching method are conducted. The results show that compared with the bilinear method, the categorized rainfall regression is more effective in decreasing the forecast biases, and improves the correlation coefficient with the observed data and the equitable threat score. The forecasts of different thresholds become more accurate after applying the frequencymatching method, with the smaller area deviation. The false alarm rate of light rain and the missing rate of heavy rain are also both reduced. Improvements of the forecasts by the categorized rainfall regression and the frequencymatching method differ in initialized times, rainfall thresholds and lead times. After the calibration of the categorized rainfall regression, the forecast initialized at 20:00 is improved with a larger magnitude than that at 08:00. The improvement of the forecast is relatively limited for rainfall thresholds of 01 mm and 50 mm, but significant for thresholds of 5 mm, 10 mm and 15 mm. Additionally, the amplitude of the improvement increases slightly over the lead time. The improvement induced by the frequencymatching method is greater for precipitation forecasts initialized at specific times that show worse performances.
2020, 48(3):428-432.
Abstract:
By use of the monthly maximum wind sequences of 70 years and 20 years from 86 national meteorological observation stations in Guangdong Province, the threeparameter Generalized Pareto Distribution (GPD) function is used to calculate the returnperiod wind speeds of 86 national meteorological observation stations, respectively. The four parameter estimation methods such as Moment Estimation (MOM), Maximum Likelihood Estimation (MLE), Likelihood Moment Estimation (LM) and Probability and Weight Moment Estimation (PWM) are used based on the PeaksOverThreshold (POT) sampling. The characterization parameter estimation indicators such as rootmeansquare error (RMSE), fitting relative deviation (〖WTBX〗R〖WTBZ〗f) and Komogorov Test with a reliability of 0.05 (〖WTBX〗K〖WTBZ〗f) are used to test the fitting effect. The results show that Probability Weight Moment Estimation (PWM) based on POT has the best fitting effect.
By use of the monthly maximum wind sequences of 70 years and 20 years from 86 national meteorological observation stations in Guangdong Province, the threeparameter Generalized Pareto Distribution (GPD) function is used to calculate the returnperiod wind speeds of 86 national meteorological observation stations, respectively. The four parameter estimation methods such as Moment Estimation (MOM), Maximum Likelihood Estimation (MLE), Likelihood Moment Estimation (LM) and Probability and Weight Moment Estimation (PWM) are used based on the PeaksOverThreshold (POT) sampling. The characterization parameter estimation indicators such as rootmeansquare error (RMSE), fitting relative deviation (〖WTBX〗R〖WTBZ〗f) and Komogorov Test with a reliability of 0.05 (〖WTBX〗K〖WTBZ〗f) are used to test the fitting effect. The results show that Probability Weight Moment Estimation (PWM) based on POT has the best fitting effect.
18 Analysis of Foehn Characteristics in Middle Section of Taihang Mountains Based on Background Method
2020, 48(3):433-437.
Abstract:
Based on the hourly monitoring data of meteorological elements in Shijiazhuang from 2009 to 2018, a new statistical method of foehns (background method) is designed. The characteristics of foehns in the middle Taihang Mountains are analyzed. The differences between the background method and the conventional foehn statistical method and its hit ratio are discussed. The results show that the background method effectively exclude the influence of largescale weather systems and radiation on the statistical results of foehns. It can ensure the accuracy of foehn process statistics. Compared with the conventional foehn statistical methods, the daily distribution characteristics of foehns are obviously improved and the number of foehn decreased significantly in the morning and increased significantly at night. The conclusion based on background method is more consistent with the characteristics of local foehns in Shijiazhuang. The statistical hit rate of foehns based on the background method is 100% in Shijiazhuang, but in the downstream area, the statistical hit rate of foehns decreased obviously with the increase of distance from the Taihang Mountains.
Based on the hourly monitoring data of meteorological elements in Shijiazhuang from 2009 to 2018, a new statistical method of foehns (background method) is designed. The characteristics of foehns in the middle Taihang Mountains are analyzed. The differences between the background method and the conventional foehn statistical method and its hit ratio are discussed. The results show that the background method effectively exclude the influence of largescale weather systems and radiation on the statistical results of foehns. It can ensure the accuracy of foehn process statistics. Compared with the conventional foehn statistical methods, the daily distribution characteristics of foehns are obviously improved and the number of foehn decreased significantly in the morning and increased significantly at night. The conclusion based on background method is more consistent with the characteristics of local foehns in Shijiazhuang. The statistical hit rate of foehns based on the background method is 100% in Shijiazhuang, but in the downstream area, the statistical hit rate of foehns decreased obviously with the increase of distance from the Taihang Mountains.
2020, 48(3):438-442.
Abstract:
Based on the radarbased lightning warning products of Zhejiang meteorological Observatory running for many years (60 min early warning, spatial resolution 1 km×1 km, four warning levels), considering the high false negative rate of Lightning Warning Products, a method of lightning warning is presented by blending lightning location data and atmospheric electric field data. The results from the new lightning warning method in 2018 are verified, with a POD (Percent of Doom) of 31.52%, FAR (False Alarm Rate) of 29.86%，and CSI (Critical Success Index) of 61.24%, which are better than those from the previous method based on singlefactor observation. It can be obviously seen that this method has more significant indication and reference for Zhejiang lightning forecasting and warning.
Based on the radarbased lightning warning products of Zhejiang meteorological Observatory running for many years (60 min early warning, spatial resolution 1 km×1 km, four warning levels), considering the high false negative rate of Lightning Warning Products, a method of lightning warning is presented by blending lightning location data and atmospheric electric field data. The results from the new lightning warning method in 2018 are verified, with a POD (Percent of Doom) of 31.52%, FAR (False Alarm Rate) of 29.86%，and CSI (Critical Success Index) of 61.24%, which are better than those from the previous method based on singlefactor observation. It can be obviously seen that this method has more significant indication and reference for Zhejiang lightning forecasting and warning.
2020, 48(3):443-450.
Abstract:
Red cartridge kiwifruit canker disease sees an uptrend in recent years in the western Guizhou as the production scale of red cartridge kiwifruits is extended quickly, and this disease has become one of the main limited factors in the production of red cartridge kiwifruits in this area. Based on the 6year observation data of the main planting areas of red cartridge kiwifruits in the western Guizhou Province, the correlation analysis method is used to study the relationship between meteorological factors and the occurrence of cartridge kiwifruit canker disease. The meteorological factors with better correlation are selected as the prediction factors of red cartridge kiwifruit canker disease. The meteorological prediction model of red cartridge kiwifruit canker disease is established based on the monitoring data of red cartridge kiwifruit canker disease. It is concluded: When the daily average temperature of 5 days or more from midDecember to early January of next year is less than 2 ℃, the daily minimum temperature was less than -2 ℃ and the daily average relative humidity is more than 75%, the canker disease will begin in the early March, with a prediction accuracy of 50%. When the average daily temperature of 5 days or more from midJanuary to late January is less than 2 ℃, the lowest daily temperature is less than -2 ℃ and the average daily relative humidity is more than 75%,the canker disease will begin in the midMarch, with a prediction accuracy of 100%. When the average daily temperature of 5 days or more from early to midFebruary is less than 2 ℃, the lowest daily temperature is less than -2 ℃ and the average daily relative humidity is more than 75%, the canker disease will beginning in late March, with an accuracy of 100%.
Red cartridge kiwifruit canker disease sees an uptrend in recent years in the western Guizhou as the production scale of red cartridge kiwifruits is extended quickly, and this disease has become one of the main limited factors in the production of red cartridge kiwifruits in this area. Based on the 6year observation data of the main planting areas of red cartridge kiwifruits in the western Guizhou Province, the correlation analysis method is used to study the relationship between meteorological factors and the occurrence of cartridge kiwifruit canker disease. The meteorological factors with better correlation are selected as the prediction factors of red cartridge kiwifruit canker disease. The meteorological prediction model of red cartridge kiwifruit canker disease is established based on the monitoring data of red cartridge kiwifruit canker disease. It is concluded: When the daily average temperature of 5 days or more from midDecember to early January of next year is less than 2 ℃, the daily minimum temperature was less than -2 ℃ and the daily average relative humidity is more than 75%, the canker disease will begin in the early March, with a prediction accuracy of 50%. When the average daily temperature of 5 days or more from midJanuary to late January is less than 2 ℃, the lowest daily temperature is less than -2 ℃ and the average daily relative humidity is more than 75%,the canker disease will begin in the midMarch, with a prediction accuracy of 100%. When the average daily temperature of 5 days or more from early to midFebruary is less than 2 ℃, the lowest daily temperature is less than -2 ℃ and the average daily relative humidity is more than 75%, the canker disease will beginning in late March, with an accuracy of 100%.
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.