Volume 47,Issue 3,2019 Table of Contents
2019, 47(3):373-379.
Abstract:
The consistency between H and V channels of polarimetric radar is the key technology for polarimetric upgrades to the operational new generation weather radar in China. The paper uses external instrument and internal test signals to analyze some key performance indicators, including dynamic range, noise coefficient, echo intensity calibration and consistency between the two channels of receivers. All these performance indicators show proper variance and meet the design requirement, while there are differences in the test results of polarimetric parameters, e.g., 〖WTBX〗Z〖WTBZ〗DR and 〖WTBX〗φ〖WTBZ〗DP. Regular inspection and correction are needed to ensure the consistency of two channels. But it is found that the amplitude and phase differences of H and V channels changed regularly with the varying azimuth. The effect of azimuth rotary joint should be taken into consideration in long term operation according to the results.
The consistency between H and V channels of polarimetric radar is the key technology for polarimetric upgrades to the operational new generation weather radar in China. The paper uses external instrument and internal test signals to analyze some key performance indicators, including dynamic range, noise coefficient, echo intensity calibration and consistency between the two channels of receivers. All these performance indicators show proper variance and meet the design requirement, while there are differences in the test results of polarimetric parameters, e.g., 〖WTBX〗Z〖WTBZ〗DR and 〖WTBX〗φ〖WTBZ〗DP. Regular inspection and correction are needed to ensure the consistency of two channels. But it is found that the amplitude and phase differences of H and V channels changed regularly with the varying azimuth. The effect of azimuth rotary joint should be taken into consideration in long term operation according to the results.
2 Study and Application of Calibration Technology for Receiving Antennas of Meteorological Satellites
2019, 47(3):380-385.
Abstract:
In the past few decades，the Fengyun meteorological satellites have progressed from the experimental phase to the operational phase. The reliability and pointing accuracy requirements for satellite signal receiving antennas are getting higher and higher. The 12meter and 4.2meter diameter antenna are used to receive the signals of the Fengyun satellites at present. The characteristics of the antennas are high speed and narrow width of the wave width, and so accurate calibration is necessary when an antenna is built. On the basis of the traditional calibration method, this paper puts forward the error calibration technique using the sun, which can further reduce the complexity of the calibration link and improve the calibration accuracy.
In the past few decades，the Fengyun meteorological satellites have progressed from the experimental phase to the operational phase. The reliability and pointing accuracy requirements for satellite signal receiving antennas are getting higher and higher. The 12meter and 4.2meter diameter antenna are used to receive the signals of the Fengyun satellites at present. The characteristics of the antennas are high speed and narrow width of the wave width, and so accurate calibration is necessary when an antenna is built. On the basis of the traditional calibration method, this paper puts forward the error calibration technique using the sun, which can further reduce the complexity of the calibration link and improve the calibration accuracy.
2019, 47(3):386-396.
Abstract:
Low visibility is one of the most serious meteorological factors affecting road traffic. Along with the technology development of digital camera and image recognition and the information shared among the meteorological and traffic departments, using camera video data along the expressway to rapid recognize the visibility becomes an important method to improve the precision of visibility temporal and spatial monitoring. In this paper, we propose a daytime road image visibility detection method based on the brightness contrast and dark channel prior principle: (1) to extract the interested road domain according to the Hough transform detection method, (2) by using the brightness contrast method, the farthest pixel point that the human eye can distinguish is used as the target point, (3) to evaluate the transmittance of the target point based on the dark channel prior principle, (4) to figure out the image visibility value by the relationship between visibility and extinction coefficient. The test indicators of this paper are visibility absolute error and visibility level error. The test data is derived from the video image data of the Wuyu section of Jingtai Expressway in Anhui Province and the NingguoHutong section of Ningji Expressway in Anhui province, and the visibility data set of the traffic weather stations near the expressway in Anhui Province. The results indicate that the method can accurately reflect the trend of visibility change, and the detection accuracy can be as high as 95%, which can be a good reference for the image visibility recognition.
Low visibility is one of the most serious meteorological factors affecting road traffic. Along with the technology development of digital camera and image recognition and the information shared among the meteorological and traffic departments, using camera video data along the expressway to rapid recognize the visibility becomes an important method to improve the precision of visibility temporal and spatial monitoring. In this paper, we propose a daytime road image visibility detection method based on the brightness contrast and dark channel prior principle: (1) to extract the interested road domain according to the Hough transform detection method, (2) by using the brightness contrast method, the farthest pixel point that the human eye can distinguish is used as the target point, (3) to evaluate the transmittance of the target point based on the dark channel prior principle, (4) to figure out the image visibility value by the relationship between visibility and extinction coefficient. The test indicators of this paper are visibility absolute error and visibility level error. The test data is derived from the video image data of the Wuyu section of Jingtai Expressway in Anhui Province and the NingguoHutong section of Ningji Expressway in Anhui province, and the visibility data set of the traffic weather stations near the expressway in Anhui Province. The results indicate that the method can accurately reflect the trend of visibility change, and the detection accuracy can be as high as 95%, which can be a good reference for the image visibility recognition.
2019, 47(3):397-401.
Abstract:
The Boundary Layer Wind Profile Radar (WPR) provides vertical, continuous, and high spatial/temporal resolution detection data for weather forecasting services. Because the frequent burning of limiters during operation in centralized radar stations across China, an Lband highpower passive limiter is designed, which introduces dualcoupling cables and a power resistor at the front part of the circuit, divided into two limits and increased heat dissipation, to theoretically reduce the power by half through the PIN diode; the multistage diodes are in parallel at the back end, and the limiting process is gradual. The limiter is characterized by high withstand power, low limiting level and low insertion loss. Using ADS software for simulation, the limiter is tested, and the results meet the requirements of design. Application of this limiter in the boundary layer WPR greatly improves radar stability.
The Boundary Layer Wind Profile Radar (WPR) provides vertical, continuous, and high spatial/temporal resolution detection data for weather forecasting services. Because the frequent burning of limiters during operation in centralized radar stations across China, an Lband highpower passive limiter is designed, which introduces dualcoupling cables and a power resistor at the front part of the circuit, divided into two limits and increased heat dissipation, to theoretically reduce the power by half through the PIN diode; the multistage diodes are in parallel at the back end, and the limiting process is gradual. The limiter is characterized by high withstand power, low limiting level and low insertion loss. Using ADS software for simulation, the limiter is tested, and the results meet the requirements of design. Application of this limiter in the boundary layer WPR greatly improves radar stability.
2019, 47(3):402-407.
Abstract:
A detection system is developed for regular sensors of automatic weather stations. This paper introduces the sensor signal acquisition circuit and the way to determine faults of sensors based on the analysis of collected data. While detecting temperature, humidity or air pressure sensor, a laboratory calibrated sensor is introduced as the standard and is detected under the same environment simultaneously with the sensor being tested. After statistical analysis, four working modes of the sensors are categorized automatically. By analyzing the code relationship of the Grey codes exported by the wind direction sensor, nine particular testing locations that are different from the regulation of metrological verification are developed and therefore all the exported codes are detected. The detection of wind speed sensors and rain gauges simulates the laboratory verification regulation to achieve quasiexperimental effects. The system has been applied in the frontline of meteorological equipment support of Guangdong Province. It shows stable performance and meets the demands of supporting service.
A detection system is developed for regular sensors of automatic weather stations. This paper introduces the sensor signal acquisition circuit and the way to determine faults of sensors based on the analysis of collected data. While detecting temperature, humidity or air pressure sensor, a laboratory calibrated sensor is introduced as the standard and is detected under the same environment simultaneously with the sensor being tested. After statistical analysis, four working modes of the sensors are categorized automatically. By analyzing the code relationship of the Grey codes exported by the wind direction sensor, nine particular testing locations that are different from the regulation of metrological verification are developed and therefore all the exported codes are detected. The detection of wind speed sensors and rain gauges simulates the laboratory verification regulation to achieve quasiexperimental effects. The system has been applied in the frontline of meteorological equipment support of Guangdong Province. It shows stable performance and meets the demands of supporting service.
2019, 47(3):408-412.
Abstract:
Visibility is an important element in meteorological, environmental and transport departments. The unified test environment and calibration standards have not been made for different visibility meters, which leads to great disparity in the results. For the unified environment, a simulation cabin has been developed. Visibility from 10 m to 50 km is simulated by fog generators and purifiers. A method has been put forward, which can eliminate the errors caused by the unevenness of air. Different models and the forward scattering visibility meters of the same model have been tested. The result shows that the difference in different models is greater than 100%. The relative error is within the range of ±5% in the same type. A correction method has been developed, which will decrease the relative error within the range of ±10% in different types.
Visibility is an important element in meteorological, environmental and transport departments. The unified test environment and calibration standards have not been made for different visibility meters, which leads to great disparity in the results. For the unified environment, a simulation cabin has been developed. Visibility from 10 m to 50 km is simulated by fog generators and purifiers. A method has been put forward, which can eliminate the errors caused by the unevenness of air. Different models and the forward scattering visibility meters of the same model have been tested. The result shows that the difference in different models is greater than 100%. The relative error is within the range of ±5% in the same type. A correction method has been developed, which will decrease the relative error within the range of ±10% in different types.
2019, 47(3):413-419.
Abstract:
This paper analyzes the power supply and consumption of a CAWS600 model regional automatic weather station in Tianjin. Using the normalized processing of the battery discharge characteristic curve, the residual capacity estimation method for the 12V38AH leadacid battery is obtained. At the same time, using the statistical characteristics of working voltage of the battery in the station, the method of extreme value judgment and time/space consistency quality control for the working voltage of the battery is proposed, and tested in the method with the observation data of 10 minutes in 2017. The test results show that the quality control method proposed in the article can effectively identify the abnormal battery site, and the positions of the abnormal batteries in the stations in 2017 can be determined 10 days in advance.
This paper analyzes the power supply and consumption of a CAWS600 model regional automatic weather station in Tianjin. Using the normalized processing of the battery discharge characteristic curve, the residual capacity estimation method for the 12V38AH leadacid battery is obtained. At the same time, using the statistical characteristics of working voltage of the battery in the station, the method of extreme value judgment and time/space consistency quality control for the working voltage of the battery is proposed, and tested in the method with the observation data of 10 minutes in 2017. The test results show that the quality control method proposed in the article can effectively identify the abnormal battery site, and the positions of the abnormal batteries in the stations in 2017 can be determined 10 days in advance.
2019, 47(3):420-425.
Abstract:
The traditional meteorological data estimation is mostly based on the interpolation methods, which require the complete observation data of the nearest neighbor stations and largely limit the application of the interpolation methods. This paper proposes a method for estimating meteorological data based on matrix completion. The proposed method estimates missing data based on the approximate lowrankness of meteorological data. The daily average temperature and sunshine hours of 662 meteorological stations in China from 2004 to 2013 are selected as the research objects. The approximate lowrankness of the data set is validated by the cumulative contribution rate of matrix singular values. Then two groups of experiments are designed. The first group of experiments considers the data estimation for different years with different sampling probabilities. The second group randomly chooses some stations and considers the data estimation when the data of the selected stations are continuously missing. Finally, the matrix completion method is employed to estimate the missing data, and the 10year average error is used as the evaluation index. Experimental results show that the matrix completion method has good estimation performance and certain robustness.
The traditional meteorological data estimation is mostly based on the interpolation methods, which require the complete observation data of the nearest neighbor stations and largely limit the application of the interpolation methods. This paper proposes a method for estimating meteorological data based on matrix completion. The proposed method estimates missing data based on the approximate lowrankness of meteorological data. The daily average temperature and sunshine hours of 662 meteorological stations in China from 2004 to 2013 are selected as the research objects. The approximate lowrankness of the data set is validated by the cumulative contribution rate of matrix singular values. Then two groups of experiments are designed. The first group of experiments considers the data estimation for different years with different sampling probabilities. The second group randomly chooses some stations and considers the data estimation when the data of the selected stations are continuously missing. Finally, the matrix completion method is employed to estimate the missing data, and the 10year average error is used as the evaluation index. Experimental results show that the matrix completion method has good estimation performance and certain robustness.
2019, 47(3):426-432.
Abstract:
The distribution of meteorological service data is an important part of the public meteorological service. The PMSDDS V1.0 (Public Meteorological Service Data Distribution Software Version 1.0) is a set of operational meteorological service data distribution system, which carries on the secondary application development to the open source transmission component libcurl, and transfers weather service data based on FTP. The software has the characteristics of the exactmatching and fuzzymatching file names that conforms to the public meteorological service product naming specification, multiparameter control, logs and so on, which effectively solved the problems of the distributed deployment of data transmission service, the tight coupling of other processes, the repeated development, and lack of logs, etc., as well as common data transmission problems such as leakage, congestion, waiting, etc. The application shows that the software is stable and the success rate of transmission is above 99.97%. Since the software runs online, the data transmission service has been deployed and monitored uniformly. According to the statistics of operational and maintenance departments, the annual deployment of transmission service increased by 50 times compared with the previous year, and the failure rate of operation and maintenance caused by transmission problems decreased by about one third year on year, which greatly improved the service efficiency.
The distribution of meteorological service data is an important part of the public meteorological service. The PMSDDS V1.0 (Public Meteorological Service Data Distribution Software Version 1.0) is a set of operational meteorological service data distribution system, which carries on the secondary application development to the open source transmission component libcurl, and transfers weather service data based on FTP. The software has the characteristics of the exactmatching and fuzzymatching file names that conforms to the public meteorological service product naming specification, multiparameter control, logs and so on, which effectively solved the problems of the distributed deployment of data transmission service, the tight coupling of other processes, the repeated development, and lack of logs, etc., as well as common data transmission problems such as leakage, congestion, waiting, etc. The application shows that the software is stable and the success rate of transmission is above 99.97%. Since the software runs online, the data transmission service has been deployed and monitored uniformly. According to the statistics of operational and maintenance departments, the annual deployment of transmission service increased by 50 times compared with the previous year, and the failure rate of operation and maintenance caused by transmission problems decreased by about one third year on year, which greatly improved the service efficiency.
10 Improvement of Data Service Capability of Provincial CIMISS Based on Distributed Storage Technology
2019, 47(3):433-438.
Abstract:
As the meteorological data continuously grows, the needs to further improve the data management and service capacity of CIMISS (China Integrated Meteorological Information Sharing System) has become increasingly urgent. The storage system of CIMISS has some problems, such as insufficient dynamic expansion ability, poor parallel computing ability and low data throughput. To solve these problems that restrict the development of CIMISS, a group of distributed file systems and a distributed database system are established. Combining with NAS (Network Attached Storage) technology, the distributed file system replaces GPFS (General Parallel File System) and sets up shared file systems to store the unstructured meteorological data. The distributed database system replaces Oracle RAC and sets up an RDBMS (Relational Database Management System) to store the structured meteorological data and index meteorological data files. The practice has proved that the proposed scheme can effectively improve the data storage capacity and concurrent response ability of CIMISS to meet the needs of meteorological operations for data storage and application in the future.
As the meteorological data continuously grows, the needs to further improve the data management and service capacity of CIMISS (China Integrated Meteorological Information Sharing System) has become increasingly urgent. The storage system of CIMISS has some problems, such as insufficient dynamic expansion ability, poor parallel computing ability and low data throughput. To solve these problems that restrict the development of CIMISS, a group of distributed file systems and a distributed database system are established. Combining with NAS (Network Attached Storage) technology, the distributed file system replaces GPFS (General Parallel File System) and sets up shared file systems to store the unstructured meteorological data. The distributed database system replaces Oracle RAC and sets up an RDBMS (Relational Database Management System) to store the structured meteorological data and index meteorological data files. The practice has proved that the proposed scheme can effectively improve the data storage capacity and concurrent response ability of CIMISS to meet the needs of meteorological operations for data storage and application in the future.
2019, 47(3):439-449.
Abstract:
Based on the daily data of 20cm evaporating pans as well as other meteorological factors of 18 automatic meteorological observation stations from 1966 to 2001 over Hainan Island, changes in pan evaporation and their causes are analyzed by the methods of ArcGIS and the mathematical statistics. The results show that the annual evaporation of Hainan Island showed a fluctuating decline, and the decrease of annual evaporation mainly occurred in spring, winter and summer. The annual evaporation was less in the northeast and greater in the southwest. The large value areas were mainly concentrated in the southwest, while the smaller ones were mainly concentrated in the northeast and middle areas. The MK test confirms that annual evaporation had significantly decreasing trends and the significant mutation year was about 1994. Among the change factors affecting evaporation, the sunshine duration and wind speed were the main factors that caused the decrease of evaporation. The influence of precipitation on the evaporation of Hainan Island was second only to the wind speed and sunshine hours. The temperature was not the main factor for decreasing evaporation, and humidity might be the influence factor of the of Hainan Island decreasing evaporation.
Based on the daily data of 20cm evaporating pans as well as other meteorological factors of 18 automatic meteorological observation stations from 1966 to 2001 over Hainan Island, changes in pan evaporation and their causes are analyzed by the methods of ArcGIS and the mathematical statistics. The results show that the annual evaporation of Hainan Island showed a fluctuating decline, and the decrease of annual evaporation mainly occurred in spring, winter and summer. The annual evaporation was less in the northeast and greater in the southwest. The large value areas were mainly concentrated in the southwest, while the smaller ones were mainly concentrated in the northeast and middle areas. The MK test confirms that annual evaporation had significantly decreasing trends and the significant mutation year was about 1994. Among the change factors affecting evaporation, the sunshine duration and wind speed were the main factors that caused the decrease of evaporation. The influence of precipitation on the evaporation of Hainan Island was second only to the wind speed and sunshine hours. The temperature was not the main factor for decreasing evaporation, and humidity might be the influence factor of the of Hainan Island decreasing evaporation.
2019, 47(3):450-459.
Abstract:
Sunshine duration is one of the elements that characterize the strength of solar radiation, and it is closely related to the utilization of light and heat energy in agriculture. The temporal and spatial variation of annual and seasonal sunshine duration in Tianshan Mountain and its causes are analyzed by using the method of anomaly variation trend, 5years moving averge, MK test and IDW residual error revision by ArcGIS, based on sunshine duration, precipitation, temperature, cloudiness, wind speed and relative humidity of 55 meteorological stations from 1961 to 2015. The conclusions show: (1) Annual and all seasonal, except in spring, variations showed a declined temporal trend. The differences in the Tianshan Mountain were significant, and the trends in the mountain area and the northern slope of the Tianshan Mountain were more obvious than that in the southern Tianshan. (2) The MannKendall mutation test shows that in recent 55 years, the mutation times of annual sunshine hours in the northern slopes of Tianshan Mountains, the sourthern slopes of Tianshan Mountains and the mountain areas were 1985, 1980 and 1988. In spring, only the mountainous area was mutated. And in winter, only the southern slopes of the Tianshan Moutains and the sunshine hours in the montains were mutated. The results show that the cloud cover and precipititation were the leading factors in the occurrence of muations. (3) There was obvious regional differences in the climatic distribution of seasonal and annual sunshine duration; generally, the sunshine duration of Tianshan Mountain showed a increasing trend from west to east and those of the plains were reater than ththose of mountain areas. In spring, the sunshine duration was higher in northeast than in southwest. In summer, the spatial distribution of sunshine duration was similar with spring, high in northeast and low in southwest. In autumn, the sunshine duration increased from south to north and higher in east than in west. The distribution of sunshine duration in winter reduced from south to north gradually. (4) The factors of precipitation, cloud amount, relative humidity showed a negative correlation with sunshine duration. There were positive seasonal correlation between sunshine duration and wind speed in the Tianshan area, except in spring. In recent 55 years, the amount of clouds and precipitation changed significantly, which were the main factors leading to the decrease of sunshine duration in the Tianshan area. The number of sunshine hours changed significantly in Tianshan Mountain.
Sunshine duration is one of the elements that characterize the strength of solar radiation, and it is closely related to the utilization of light and heat energy in agriculture. The temporal and spatial variation of annual and seasonal sunshine duration in Tianshan Mountain and its causes are analyzed by using the method of anomaly variation trend, 5years moving averge, MK test and IDW residual error revision by ArcGIS, based on sunshine duration, precipitation, temperature, cloudiness, wind speed and relative humidity of 55 meteorological stations from 1961 to 2015. The conclusions show: (1) Annual and all seasonal, except in spring, variations showed a declined temporal trend. The differences in the Tianshan Mountain were significant, and the trends in the mountain area and the northern slope of the Tianshan Mountain were more obvious than that in the southern Tianshan. (2) The MannKendall mutation test shows that in recent 55 years, the mutation times of annual sunshine hours in the northern slopes of Tianshan Mountains, the sourthern slopes of Tianshan Mountains and the mountain areas were 1985, 1980 and 1988. In spring, only the mountainous area was mutated. And in winter, only the southern slopes of the Tianshan Moutains and the sunshine hours in the montains were mutated. The results show that the cloud cover and precipititation were the leading factors in the occurrence of muations. (3) There was obvious regional differences in the climatic distribution of seasonal and annual sunshine duration; generally, the sunshine duration of Tianshan Mountain showed a increasing trend from west to east and those of the plains were reater than ththose of mountain areas. In spring, the sunshine duration was higher in northeast than in southwest. In summer, the spatial distribution of sunshine duration was similar with spring, high in northeast and low in southwest. In autumn, the sunshine duration increased from south to north and higher in east than in west. The distribution of sunshine duration in winter reduced from south to north gradually. (4) The factors of precipitation, cloud amount, relative humidity showed a negative correlation with sunshine duration. There were positive seasonal correlation between sunshine duration and wind speed in the Tianshan area, except in spring. In recent 55 years, the amount of clouds and precipitation changed significantly, which were the main factors leading to the decrease of sunshine duration in the Tianshan area. The number of sunshine hours changed significantly in Tianshan Mountain.
2019, 47(3):460-468.
Abstract:
The GFS (Global Forecasting System) reanalysis and JMA (Japan Meteorological Agency) reanalysis data are applied as the initial conditions for the simulation of the super Typhoon Saomai in 2006 respectively in this study. Based on the WRF (Weather Research and Forecasting) Model, numerical simulations were conducted to analyze the influence of different initial conditions on the internal structure and movement path for Saomai. The results show: For the forecasts of the 500 hPa geopotential field and the composite field (such as water vapor and temperature) of 850 hPa, GFS and JMA data are able to well grasp the overall flow field situation. JMA data are superior to GFS data for simulating fields such as the wind speed (700 hPa and nearsurface), precipitation, radar reflectivity, minimum sea level pressure, and maximum wind speed. For the typhoon track forecast, JMA data in the first 15 hours are better than GFS data, but after 15 hours, both forecasting fields have a significant deviation.
The GFS (Global Forecasting System) reanalysis and JMA (Japan Meteorological Agency) reanalysis data are applied as the initial conditions for the simulation of the super Typhoon Saomai in 2006 respectively in this study. Based on the WRF (Weather Research and Forecasting) Model, numerical simulations were conducted to analyze the influence of different initial conditions on the internal structure and movement path for Saomai. The results show: For the forecasts of the 500 hPa geopotential field and the composite field (such as water vapor and temperature) of 850 hPa, GFS and JMA data are able to well grasp the overall flow field situation. JMA data are superior to GFS data for simulating fields such as the wind speed (700 hPa and nearsurface), precipitation, radar reflectivity, minimum sea level pressure, and maximum wind speed. For the typhoon track forecast, JMA data in the first 15 hours are better than GFS data, but after 15 hours, both forecasting fields have a significant deviation.
2019, 47(3):469-475.
Abstract:
Based on the conventional observed data, NCEP/NCAR 1°×1° reanalysis data and the intensive observed data of automatic weather stations, two typical torrential rain processes during the Meiyu period of 21 to 22 and 24 to 25 June 2017 are compared. The differences are as follows: (1) The former at lower levels was a warm shear line, and the latter was a stationary front shear line. The slope of the former was about 45°, and that of the latter was nearly 90°. On the other hand, the low level jet of the latter was stronger than that of the former. (2) The water vapor of the former came from the East China Sea and then the South China Sea; that of the latter came from both South China Sea and East China Sea, which had stronger vertically integrated moisture transport. (3) The former was located near the zero isoline of moist potential vorticity in Midwest Zhejiang Province, which means that the former was triggered by the cold air activities at lower levels. The latter was caused by the middlelevel cold air overlying warmwet air transported by the southwest lower jet stream, which had a positive (negative) value at upper (lower) levels. (4) The latter had a high E index center and negative Δθ58 in Midwest Zhejiang Province, where summermonsoon highhumidity and highenergy masses accumulated in this area, and smallscale convective systems frequently developed. However, the former had positive values of Δθ58 in most parts of Zhejiang Province, over which the potential stratification was relatively stable.
Based on the conventional observed data, NCEP/NCAR 1°×1° reanalysis data and the intensive observed data of automatic weather stations, two typical torrential rain processes during the Meiyu period of 21 to 22 and 24 to 25 June 2017 are compared. The differences are as follows: (1) The former at lower levels was a warm shear line, and the latter was a stationary front shear line. The slope of the former was about 45°, and that of the latter was nearly 90°. On the other hand, the low level jet of the latter was stronger than that of the former. (2) The water vapor of the former came from the East China Sea and then the South China Sea; that of the latter came from both South China Sea and East China Sea, which had stronger vertically integrated moisture transport. (3) The former was located near the zero isoline of moist potential vorticity in Midwest Zhejiang Province, which means that the former was triggered by the cold air activities at lower levels. The latter was caused by the middlelevel cold air overlying warmwet air transported by the southwest lower jet stream, which had a positive (negative) value at upper (lower) levels. (4) The latter had a high E index center and negative Δθ58 in Midwest Zhejiang Province, where summermonsoon highhumidity and highenergy masses accumulated in this area, and smallscale convective systems frequently developed. However, the former had positive values of Δθ58 in most parts of Zhejiang Province, over which the potential stratification was relatively stable.
2019, 47(3):476-485.
Abstract:
In this paper, based on the 16 physical quantities calculated by the Hohhot radiosonde station, the differences in physical quantities between the hail, thunderstorm gale and shortterm heavy precipitation in Hohhot from June to August 2012 to 2016 are analyzed. The results show that: (1) If the revised CAPE is greater than or equal to 1000 J〖DK〗·kg-1, the 0 ℃ layer height is about 4200 m and the -20 ℃ layer height around 7200 m, the temperature differences at 500 hPa and 850 hPa up to -25 ℃, and the height of the atmospheric temperature inversion layer is above 2 km. It can be basically determined that hail weather will occur. (2) Shortterm heavy precipitation depends more on the water vapor and has stronger thermal instability. The lowerlevel difference between temperature and dew point, Δθse (500-850) and Precipitable Water Vapor (PWV) are also important criterions for shortterm heavy precipitation weather. (3) The early warning indexes of strong convective weather in Hohhot can be established as: The revised DCAPE of a thunderstorm gale is significantly larger than that of hail and shortterm heavy precipitation weather, which is about twice as large as the other two types of weather， while the revised CAPE is slightly smaller. Finally, the threshold sizes of all kinds of forecast factors can be defined by means of the quartile division method, the method of ≥70% proportion (the proportion of severe convective weather samples is more than 70%) and the mean threshold method. The statistical test indicates that the hit rate of the threshold index determined by the mean method, up to more than 50%, is of higher reference value.
In this paper, based on the 16 physical quantities calculated by the Hohhot radiosonde station, the differences in physical quantities between the hail, thunderstorm gale and shortterm heavy precipitation in Hohhot from June to August 2012 to 2016 are analyzed. The results show that: (1) If the revised CAPE is greater than or equal to 1000 J〖DK〗·kg-1, the 0 ℃ layer height is about 4200 m and the -20 ℃ layer height around 7200 m, the temperature differences at 500 hPa and 850 hPa up to -25 ℃, and the height of the atmospheric temperature inversion layer is above 2 km. It can be basically determined that hail weather will occur. (2) Shortterm heavy precipitation depends more on the water vapor and has stronger thermal instability. The lowerlevel difference between temperature and dew point, Δθse (500-850) and Precipitable Water Vapor (PWV) are also important criterions for shortterm heavy precipitation weather. (3) The early warning indexes of strong convective weather in Hohhot can be established as: The revised DCAPE of a thunderstorm gale is significantly larger than that of hail and shortterm heavy precipitation weather, which is about twice as large as the other two types of weather， while the revised CAPE is slightly smaller. Finally, the threshold sizes of all kinds of forecast factors can be defined by means of the quartile division method, the method of ≥70% proportion (the proportion of severe convective weather samples is more than 70%) and the mean threshold method. The statistical test indicates that the hit rate of the threshold index determined by the mean method, up to more than 50%, is of higher reference value.
Huang Yanbin
,
Mao Zhiyuan
,
Xing Fenghua
,
Chen Zhichao
,
Xing Zengwen
,
Li Guangwei
,
Zou Jingping
2019, 47(3):486-494.
Abstract:
The experiment of randomized effectiveness evaluation of weather modification was conducted in 2015 an 2016 through the warmcloud smog generators at Bawang Mountain of Hainan Province. The test samples were randomly distinguished into 2 groups (seeded and noseeded), with a total number of 34. The statistical and physical effectiveness of all the test samples is analyzed with the data from the local automatic rainfall stations, Doppler radar and TITAN system, and the results are as follows: The average absolute rainfall improvement of the unseeded test samples is 2.97 mm per 2 hours, and the average rainfall improvement of the seeded test samples is 3.364 mm per 2 hours. The significant analysis of test samples indicates that the target cloud rainfall data between seeded and noseeded test samples are totally different; the physical effectiveness is analyzed with the data of the Doppler radar and TITAN system, and the physical evidences of warmcloud weather modification are evaluated by analyzing the difference between maximum combined radar reflectivity after the seeding moment. The results show that the maximum combined reflectivity, liquid water content and maximum echo height of the seeded group tend to grow stronger than theses of the noseeded group in the developing stage of cumulonimbus clouds. In the weaken stage of cumulonimbus clouds, the weaken trend of echoes tends to be abated in most of the seeded test samples.
The experiment of randomized effectiveness evaluation of weather modification was conducted in 2015 an 2016 through the warmcloud smog generators at Bawang Mountain of Hainan Province. The test samples were randomly distinguished into 2 groups (seeded and noseeded), with a total number of 34. The statistical and physical effectiveness of all the test samples is analyzed with the data from the local automatic rainfall stations, Doppler radar and TITAN system, and the results are as follows: The average absolute rainfall improvement of the unseeded test samples is 2.97 mm per 2 hours, and the average rainfall improvement of the seeded test samples is 3.364 mm per 2 hours. The significant analysis of test samples indicates that the target cloud rainfall data between seeded and noseeded test samples are totally different; the physical effectiveness is analyzed with the data of the Doppler radar and TITAN system, and the physical evidences of warmcloud weather modification are evaluated by analyzing the difference between maximum combined radar reflectivity after the seeding moment. The results show that the maximum combined reflectivity, liquid water content and maximum echo height of the seeded group tend to grow stronger than theses of the noseeded group in the developing stage of cumulonimbus clouds. In the weaken stage of cumulonimbus clouds, the weaken trend of echoes tends to be abated in most of the seeded test samples.
17 Comparison of Cloud Top Height Observation between FY2F Satellite and MillimeterWave Cloud Radar
2019, 47(3):495-501.
Abstract:
The FY2 geostationary satellite spectral data consist of several detection channels, including visible, water vapor, mediumlong wavelength infrared and multichannel. Among these channels, the multichannel data can provide satellite cloud top temperature data. This paper, based on FY2F satellite cloud top temperature data, combined with the local realtime ratiosonde data, retrieves the cloud top height from the satellite data of clouds over the southern suburbs of Beijing and makes comparison with the groundbased millimeterwave cloud radar detection of cloud top height to analyze the cloud top height observation results under the three kinds of cloud thickness. The results indicate that the match degree of two sorts of measurements is affected by the geometric cloud thickness, and the coincidence degree shows the best for thick clouds and the worst for thin clouds.
The FY2 geostationary satellite spectral data consist of several detection channels, including visible, water vapor, mediumlong wavelength infrared and multichannel. Among these channels, the multichannel data can provide satellite cloud top temperature data. This paper, based on FY2F satellite cloud top temperature data, combined with the local realtime ratiosonde data, retrieves the cloud top height from the satellite data of clouds over the southern suburbs of Beijing and makes comparison with the groundbased millimeterwave cloud radar detection of cloud top height to analyze the cloud top height observation results under the three kinds of cloud thickness. The results indicate that the match degree of two sorts of measurements is affected by the geometric cloud thickness, and the coincidence degree shows the best for thick clouds and the worst for thin clouds.
2019, 47(3):502-507.
Abstract:
On 11 December 2016, China launched FY4A, a newgeneration geostationary meteorological satellite, whose high temporal and spatial resolution can enhance the monitoring applications in aeronautical meteorology. In order to better apply the various observation products of FY4A satellite, this paper uses the Python language to realize decoding and visualizing of the 2km and 4km resolution full discs, the visible and infrared images over China, and 7.8km resolution lightning monitoring data detected by the AGRI observation instrument of FY4A satellite, and compares the resulted satellite images with those from the website of the National Satellite Meteorological Center that are open to public. The results show that the two sorts of images are consistent and can be used in aeronautical meteorological services. The Python language syntax is concise and has fast reading speed for satellite HDF and NC format data. Python’s Numpy toolkit based on matrix operation can quickly process satellite observation data. The various projection methods in the Basemap library are available for operational application, which is worthy of promotion.
On 11 December 2016, China launched FY4A, a newgeneration geostationary meteorological satellite, whose high temporal and spatial resolution can enhance the monitoring applications in aeronautical meteorology. In order to better apply the various observation products of FY4A satellite, this paper uses the Python language to realize decoding and visualizing of the 2km and 4km resolution full discs, the visible and infrared images over China, and 7.8km resolution lightning monitoring data detected by the AGRI observation instrument of FY4A satellite, and compares the resulted satellite images with those from the website of the National Satellite Meteorological Center that are open to public. The results show that the two sorts of images are consistent and can be used in aeronautical meteorological services. The Python language syntax is concise and has fast reading speed for satellite HDF and NC format data. Python’s Numpy toolkit based on matrix operation can quickly process satellite observation data. The various projection methods in the Basemap library are available for operational application, which is worthy of promotion.
19 Construction of Atmospheric Weighted Average Temperature Model for Hong Kong and Its Application
2019, 47(3):508-512.
Abstract:
In order to improve the calculation accuracy and efficiency of the weighted average temperature in precipitable water vapor, this paper uses Hong Kong as an example to design an atmospheric weighted average temperature model based on ground pressure in 2017. The model is validated by the radiosonde data from 2014 to 2016. The results show that the model has good consistency with the weighted average temperature obtained by the radiosonde data and has high precision. Based on the air pressure regression model and the air temperature regression model, the groundbased radiosonde inversion was performed in July 2017 for Hong Kong, and the inversion accuracy of the new model was verified. The results show that the model can satisfactorily meet the accuracy requirements of the groundbased inversion of precipitable water vapor, and the inversion accuracy of the regression model is better than that of the temperature regression model.
In order to improve the calculation accuracy and efficiency of the weighted average temperature in precipitable water vapor, this paper uses Hong Kong as an example to design an atmospheric weighted average temperature model based on ground pressure in 2017. The model is validated by the radiosonde data from 2014 to 2016. The results show that the model has good consistency with the weighted average temperature obtained by the radiosonde data and has high precision. Based on the air pressure regression model and the air temperature regression model, the groundbased radiosonde inversion was performed in July 2017 for Hong Kong, and the inversion accuracy of the new model was verified. The results show that the model can satisfactorily meet the accuracy requirements of the groundbased inversion of precipitable water vapor, and the inversion accuracy of the regression model is better than that of the temperature regression model.
2019, 47(3):513-519.
Abstract:
The influences of geographic parameters (elevation, slope, aspect, land cover type and soil electric conductivity) on cloudtoground (CG) lightning in Zhejiang Province are quantitatively studied based on the CG lightning data in 2007 and 2016, DEM data (Digital Elevation Model), land cover type data and the HWSDbased China Soil Map (Harmonized World Soil Database). The results show that CG lightning in Zhejiang Province is mainly concentrated in the range of 0 to 600 m above the sea level, and 0°to 30° with respect to the slope. As for the aspect, the highest number of CG lightning is in the southeast, and the lowest is in the west. Besides, the forest area has the largest number of CG lightning, whereas the wetland has the smallest one. The corresponding soil electric conductivity of the CG lightning is mainly focused on 0.1 dS/m. Taking into account the proportion of area, the number of CG lightning per square kilometer increases firstly, following a decrease trend with the rise of elevation, slope, and soil electric conductivity, respectively. The highest frequency of CG lightning is found in the southern and southeastern slope areas, and the lowest is in the western and southwestern slope areas. The urban area covered with buildings has the largest number of CG lightning per square kilometer, while the water body has the smallest one. The average ground flash intensity decreases first and then increases with the increase of elevation; the mean lightning current steepness shows a decreasing trend with increasing elevation; and these two parameters decrease with the increasing slope and rise gradually with the increase of soil electric conductivity. The correlation analysis between average geographic parameters and lightning activity based on the 5 km×5 km grids shows that both lightning current intensity and steepness have a negative correlation with elevation and slope, respectively.
The influences of geographic parameters (elevation, slope, aspect, land cover type and soil electric conductivity) on cloudtoground (CG) lightning in Zhejiang Province are quantitatively studied based on the CG lightning data in 2007 and 2016, DEM data (Digital Elevation Model), land cover type data and the HWSDbased China Soil Map (Harmonized World Soil Database). The results show that CG lightning in Zhejiang Province is mainly concentrated in the range of 0 to 600 m above the sea level, and 0°to 30° with respect to the slope. As for the aspect, the highest number of CG lightning is in the southeast, and the lowest is in the west. Besides, the forest area has the largest number of CG lightning, whereas the wetland has the smallest one. The corresponding soil electric conductivity of the CG lightning is mainly focused on 0.1 dS/m. Taking into account the proportion of area, the number of CG lightning per square kilometer increases firstly, following a decrease trend with the rise of elevation, slope, and soil electric conductivity, respectively. The highest frequency of CG lightning is found in the southern and southeastern slope areas, and the lowest is in the western and southwestern slope areas. The urban area covered with buildings has the largest number of CG lightning per square kilometer, while the water body has the smallest one. The average ground flash intensity decreases first and then increases with the increase of elevation; the mean lightning current steepness shows a decreasing trend with increasing elevation; and these two parameters decrease with the increasing slope and rise gradually with the increase of soil electric conductivity. The correlation analysis between average geographic parameters and lightning activity based on the 5 km×5 km grids shows that both lightning current intensity and steepness have a negative correlation with elevation and slope, respectively.
2019, 47(3):520-525.
Abstract:
Climatic and ecological factors have significant impacts on vectorborne diseases. The potential climatic and ecological factors affecting transmission risk of 〖WTBX〗Schistosomiasis〖WTBZ〗 in China are selected based on previous research results, and then the dominant factors are determined by contribution percentages to the transmission risk of 〖WTBX〗Schistosomiasis〖WTBZ〗 in China. At last, the relation model between 〖WTBX〗Schistosomiasis 〖WTBZ〗and dominant factors based on MaxEnt to model the transmission risk of〖WTBX〗 Schistosomiasis〖WTBZ〗 in China is developed and its modelling results are assessed as well. The results show that the dominant climatic and ecological factors affecting the transmission risk of〖WTBX〗 Schistosomiasis〖WTBZ〗 in China are annual precipitation, mean temperature of the warmest month, the number of days with temperature over 10 ℃ and enhanced vegetation index, and the accumulated contribution percentage account for 98.6% of the used potential factors. According to the Receiver Operating Characteristic (ROC) curve, Area Under Curve (AUC) is 0917; i.e., the MaxEnt model based on dominant factors affecting 〖WTBX〗Schistosomiasis〖WTBZ〗 can model the transmission risk in China “very good”. The MaxEnt model results show that the medium and high transmission risk zone of〖WTBX〗 Schistosomiasis〖WTBZ〗 in China are located in Southern Jiangsu, Northern Zhejiang, Central Guangxi, Northern Guangdong, Northern Yunnan, Central Sichuan and Eastern Hubei, Northeastern Hunan, Central Anhui and Northern Jiangxi, etc. In conclusion, MaxEnt can model well the transmission risk of 〖WTBX〗Schistosomiasis〖WTBZ〗 in China under the impact of climatic and ecological factors, which can provide a tool to assess the impact of climate change on the transmission risk of〖WTBX〗 Schistosomiasis〖WTBZ〗 in China and reference to make preventive measures.
Climatic and ecological factors have significant impacts on vectorborne diseases. The potential climatic and ecological factors affecting transmission risk of 〖WTBX〗Schistosomiasis〖WTBZ〗 in China are selected based on previous research results, and then the dominant factors are determined by contribution percentages to the transmission risk of 〖WTBX〗Schistosomiasis〖WTBZ〗 in China. At last, the relation model between 〖WTBX〗Schistosomiasis 〖WTBZ〗and dominant factors based on MaxEnt to model the transmission risk of〖WTBX〗 Schistosomiasis〖WTBZ〗 in China is developed and its modelling results are assessed as well. The results show that the dominant climatic and ecological factors affecting the transmission risk of〖WTBX〗 Schistosomiasis〖WTBZ〗 in China are annual precipitation, mean temperature of the warmest month, the number of days with temperature over 10 ℃ and enhanced vegetation index, and the accumulated contribution percentage account for 98.6% of the used potential factors. According to the Receiver Operating Characteristic (ROC) curve, Area Under Curve (AUC) is 0917; i.e., the MaxEnt model based on dominant factors affecting 〖WTBX〗Schistosomiasis〖WTBZ〗 can model the transmission risk in China “very good”. The MaxEnt model results show that the medium and high transmission risk zone of〖WTBX〗 Schistosomiasis〖WTBZ〗 in China are located in Southern Jiangsu, Northern Zhejiang, Central Guangxi, Northern Guangdong, Northern Yunnan, Central Sichuan and Eastern Hubei, Northeastern Hunan, Central Anhui and Northern Jiangxi, etc. In conclusion, MaxEnt can model well the transmission risk of 〖WTBX〗Schistosomiasis〖WTBZ〗 in China under the impact of climatic and ecological factors, which can provide a tool to assess the impact of climate change on the transmission risk of〖WTBX〗 Schistosomiasis〖WTBZ〗 in China and reference to make preventive measures.
2019, 47(3):526-530.
Abstract:
Yellow stem borer is one of the main pests of rice, and it can breed four complete generations in one year in Tianyang of Guangxi. By means of the insect data during the flourishing period of yellow stem borer provided by the agricultural and plant protection departments, as well as meteorological observations, adopting the stepwise regression analysis method, a meteorological early warning model of the beginning date of yellow stem borer growth peak is established. The results show that the differences between the model output and actual data for each generation are 3 days, and the historical fitting accuracy is 82.2% to 92.9%. A trial earlywarning of 2015 and 2016 was made: the difference between first generation forecast and actual situation is 3 days, and differences are 1 to 2 days for the second to fourth generations. The correction rate of historical fitting of the model and the error range of test results are satisfactory, which can be put into the application of daily service.
Yellow stem borer is one of the main pests of rice, and it can breed four complete generations in one year in Tianyang of Guangxi. By means of the insect data during the flourishing period of yellow stem borer provided by the agricultural and plant protection departments, as well as meteorological observations, adopting the stepwise regression analysis method, a meteorological early warning model of the beginning date of yellow stem borer growth peak is established. The results show that the differences between the model output and actual data for each generation are 3 days, and the historical fitting accuracy is 82.2% to 92.9%. A trial earlywarning of 2015 and 2016 was made: the difference between first generation forecast and actual situation is 3 days, and differences are 1 to 2 days for the second to fourth generations. The correction rate of historical fitting of the model and the error range of test results are satisfactory, which can be put into the application of daily service.
2019, 47(3):531-538.
Abstract:
Combining virtual reality with meteorological application can effectively overcome the limitations of traditional models in the meteorological field, and is a main research direction of virtual reality technology. The definition and composition of virtual reality technology are briefly introduced, and its development is divided into three stages: germination, preliminary application and comprehensive development; meanwhile, the representative achievements of each stage are summarized. The theoretical research achievements of virtual reality technology in weather phenomena, weather systems and numerical forecast products are discussed in detail. In addition, the typical cases of applying virtual reality technology in the fields such as the training of meteorological sounding equipment maintenance, film and television publicity and meteorological popularization are analyzed and summarized. The problems faced by virtual reality technology in meteorological application are discussed from two perspectives: virtual reality industry and its combination with meteorological application. The last part of this paper discusses the possible research direction and future prospects.
Combining virtual reality with meteorological application can effectively overcome the limitations of traditional models in the meteorological field, and is a main research direction of virtual reality technology. The definition and composition of virtual reality technology are briefly introduced, and its development is divided into three stages: germination, preliminary application and comprehensive development; meanwhile, the representative achievements of each stage are summarized. The theoretical research achievements of virtual reality technology in weather phenomena, weather systems and numerical forecast products are discussed in detail. In addition, the typical cases of applying virtual reality technology in the fields such as the training of meteorological sounding equipment maintenance, film and television publicity and meteorological popularization are analyzed and summarized. The problems faced by virtual reality technology in meteorological application are discussed from two perspectives: virtual reality industry and its combination with meteorological application. The last part of this paper discusses the possible research direction and future prospects.
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.