Volume 49,Issue 1,2021 Table of Contents
2021, 49(1):1-6.
Abstract:
Aiming at enriching the technical means and improving the accuracy of meteorological detection, a new design of a meteorological detection system based on the highaltitude and highspeed UAV (Unmanned Aerial Vehicle) is proposed. The composition, interface and control logic of the system are designed and optimized, in order to realize the highaltitude and longdistance meteorological detection. A spiral structure which greatly increases the number of meteorological task loads is firstly applied, makes a single meteorological payload be able to contain 24 radiosondes. As a typical application of civilmilitary integration, the engineering products of the meteorological detection system have finished the functional, mechanics and environment tests. The test results show that the system is safe and effective, and the requirements of meteorological detection tasks are satisfied. The interface design of the meteorological detection system follows the principles of generalization and standardization, which is easy to be extended to other existing UAV platforms and has broad application prospects.
Aiming at enriching the technical means and improving the accuracy of meteorological detection, a new design of a meteorological detection system based on the highaltitude and highspeed UAV (Unmanned Aerial Vehicle) is proposed. The composition, interface and control logic of the system are designed and optimized, in order to realize the highaltitude and longdistance meteorological detection. A spiral structure which greatly increases the number of meteorological task loads is firstly applied, makes a single meteorological payload be able to contain 24 radiosondes. As a typical application of civilmilitary integration, the engineering products of the meteorological detection system have finished the functional, mechanics and environment tests. The test results show that the system is safe and effective, and the requirements of meteorological detection tasks are satisfied. The interface design of the meteorological detection system follows the principles of generalization and standardization, which is easy to be extended to other existing UAV platforms and has broad application prospects.
2021, 49(1):7-11.
Abstract:
In order to solve the problem that there is no verification and calibration capability for wind speed sensors above 70 m/s in China, this paper designs a wind tunnel with the 90 m/s upper limit of wind speed. The moving guide rail makes the test section with open/close dualpurpose. The overall size of the wind tunnel is 26 m×10 m×4.2 m (length, width and height). The velocity range is 0.4 to 90.74 m/s. The control system adopts the fully digital design of physical quantity to meet the automatic demand of metrological experiments. The performance indicators have passed the acceptance test, which means that the tunnel fulfills the test specification for meteorological low speed wind tunnel performance.
In order to solve the problem that there is no verification and calibration capability for wind speed sensors above 70 m/s in China, this paper designs a wind tunnel with the 90 m/s upper limit of wind speed. The moving guide rail makes the test section with open/close dualpurpose. The overall size of the wind tunnel is 26 m×10 m×4.2 m (length, width and height). The velocity range is 0.4 to 90.74 m/s. The control system adopts the fully digital design of physical quantity to meet the automatic demand of metrological experiments. The performance indicators have passed the acceptance test, which means that the tunnel fulfills the test specification for meteorological low speed wind tunnel performance.
2021, 49(1):12-17.
Abstract:
In view of the lack of detection standards for forward scattering visibility meters in meteorological industry, the laboratory test method of forward scattering visibility meters is studied. In this paper, the working principles of the forward scattering visibility meter is introduced; the composition and technical requirements of the measuring standard equipment are expounded; the testing items and testing methods of forward scattering visibility meters are described in detail; and the indoor measured results of several forward scattering visibility meters are presented. The results show that it is feasible to measure the measurement range and indication error by simulating the visibility in the test chamber, and the transmission instrument can be selected as the measuring standard. The response time can be measured by placing a scattering plate or a mask to generate a sudden signal.
In view of the lack of detection standards for forward scattering visibility meters in meteorological industry, the laboratory test method of forward scattering visibility meters is studied. In this paper, the working principles of the forward scattering visibility meter is introduced; the composition and technical requirements of the measuring standard equipment are expounded; the testing items and testing methods of forward scattering visibility meters are described in detail; and the indoor measured results of several forward scattering visibility meters are presented. The results show that it is feasible to measure the measurement range and indication error by simulating the visibility in the test chamber, and the transmission instrument can be selected as the measuring standard. The response time can be measured by placing a scattering plate or a mask to generate a sudden signal.
2021, 49(1):18-24.
Abstract:
The purpose of precipitation nowcasting is to predict the distribution of local precipitation intensity within the coming two hours, and accurate extrapolation radar images can provide accurate spacetime data reference for nowcasting. The application of Recurrent Neural Network (RNN) to meteorological radar image extrapolation has brought better results in recent two years. Based on the analysis of convLSTM and TrajLSTM, the extrapolation model is improved from two aspects: the number of layers of radar data and the loss function, and the experiment is carried out with Chengdu and Yueyang radar data and an open competition data set. The experimental results show that the improved model can better capture the spacetime correlation and keep more image details.
The purpose of precipitation nowcasting is to predict the distribution of local precipitation intensity within the coming two hours, and accurate extrapolation radar images can provide accurate spacetime data reference for nowcasting. The application of Recurrent Neural Network (RNN) to meteorological radar image extrapolation has brought better results in recent two years. Based on the analysis of convLSTM and TrajLSTM, the extrapolation model is improved from two aspects: the number of layers of radar data and the loss function, and the experiment is carried out with Chengdu and Yueyang radar data and an open competition data set. The experimental results show that the improved model can better capture the spacetime correlation and keep more image details.
5 Identification of Thunderstorm Processes Based on Radar Product Threshold and Hearing-Thunder Radius
2021, 49(1):25-31.
Abstract:
To provide radar product thresholds close to the actual for thunderstorm identifying, tracking and nowcasting systems, and to establish the algorithm of thunderstorm day discrimination based on radar observation, the artificial thunderstorm observation and radar data are used to construct the matching rate model, and the cumulative departure method is adopted to identify the matching rate of inflection point to determine the thresholds and the optimal radius of hearing thunders, and the echo area of the threshold is given. Taking the Changde meteorological station as an example, using this method, it is resulted that: (1) The threshold value of radar product is 38.5 dBz, and the optimal radius of hearing thunders reaches 25 km, which is larger than the radius obtained by comparing the lightning location data with the artificial thunderstorm day. The echo area threshold value is 73 km2, and the evaluation indicates that the threshold values are appropriate. (2) The seasonal variation of thunderstorms should be taken into account when using various thresholds and radar data to judge thunderstorm days. The performance is satisfactory in the Changde area from March to August. (3) When using this method, the matching rate model should be constructed based on the single radar or radar mosaic data samples of the longtime series selected according to the historical hearingthunder locations.
To provide radar product thresholds close to the actual for thunderstorm identifying, tracking and nowcasting systems, and to establish the algorithm of thunderstorm day discrimination based on radar observation, the artificial thunderstorm observation and radar data are used to construct the matching rate model, and the cumulative departure method is adopted to identify the matching rate of inflection point to determine the thresholds and the optimal radius of hearing thunders, and the echo area of the threshold is given. Taking the Changde meteorological station as an example, using this method, it is resulted that: (1) The threshold value of radar product is 38.5 dBz, and the optimal radius of hearing thunders reaches 25 km, which is larger than the radius obtained by comparing the lightning location data with the artificial thunderstorm day. The echo area threshold value is 73 km2, and the evaluation indicates that the threshold values are appropriate. (2) The seasonal variation of thunderstorms should be taken into account when using various thresholds and radar data to judge thunderstorm days. The performance is satisfactory in the Changde area from March to August. (3) When using this method, the matching rate model should be constructed based on the single radar or radar mosaic data samples of the longtime series selected according to the historical hearingthunder locations.
2021, 49(1):32-39.
Abstract:
In order to verify the performance of the raindropspectrum precipitation phenomenon sensor, the PARSIVEL raindropspectrum precipitation phenomenon sensor deployed at Jiangning by the Nanjing Meteorological Service is used to collate the observation data of weather phenomena from January to November 2018, and the performance of the sensor for different types of precipitation is analyzed. The conclusions are as follows: (1) The raindropspectrum precipitation phenomenon sensor has good consistency with manual observations in general, but there are some differences in precipitation duration and precipitation types. (2) In the daytime, the total precipitation duration of manual observation is obviously higher than that of the sensor, and the main reason is that manual observation might ignore the time between precipitation events, while the sensor might miss very light precipitation; the precipitation classification of manual observation is rough, and the fine changes of precipitation may be neglected, while the sensor is able to detect the shortterm changes in rainfall, the conversion of drizzle and rainfall, the conversion of rainfall and snow, etc. (3) At night, the manual observation may ignore a certain drizzle or rainfall, whereas the sensor tends to miss the light rainfall, and rains might be misjudged as graupels or snowfall. Therefore, the algorithm for classifying precipitation still needs to be improved.
In order to verify the performance of the raindropspectrum precipitation phenomenon sensor, the PARSIVEL raindropspectrum precipitation phenomenon sensor deployed at Jiangning by the Nanjing Meteorological Service is used to collate the observation data of weather phenomena from January to November 2018, and the performance of the sensor for different types of precipitation is analyzed. The conclusions are as follows: (1) The raindropspectrum precipitation phenomenon sensor has good consistency with manual observations in general, but there are some differences in precipitation duration and precipitation types. (2) In the daytime, the total precipitation duration of manual observation is obviously higher than that of the sensor, and the main reason is that manual observation might ignore the time between precipitation events, while the sensor might miss very light precipitation; the precipitation classification of manual observation is rough, and the fine changes of precipitation may be neglected, while the sensor is able to detect the shortterm changes in rainfall, the conversion of drizzle and rainfall, the conversion of rainfall and snow, etc. (3) At night, the manual observation may ignore a certain drizzle or rainfall, whereas the sensor tends to miss the light rainfall, and rains might be misjudged as graupels or snowfall. Therefore, the algorithm for classifying precipitation still needs to be improved.
2021, 49(1):40-45.
Abstract:
The DSG5 precipitation weather phenomenon instruments have been installed in a large number of domestic stations, and a great deal of valuable data have been observed and recorded. This paper analyzes the data structure, content and application of the DSG5 precipitation weather phenomenon instrument data through a precipitation weather process. The analysis finds that the precipitation start time judged by the DSG5 precipitation weather phenomenon instrument is later than the actual, and the end time of precipitation is earlier than the actual, and some weak precipitation cannot be judged; the raindrop spectrum data can reveal the fine structure and evolution characteristics of the precipitation process, deepen the understanding of the precipitation process, and help to accurately and intuitively deal with the problem of the mismatch between precipitation and weather phenomena in automatic meteorological observations. From the raindrop spectrum data, there are many small raindrops with a diameter of about 0.3 mm in the precipitation process, but the raindrops with a diameter of more than 1 mm have the larger impact on precipitation intensity. With the increase of raindrops with a diameter of more than 1 mm, the ground precipitation increases significantly.
The DSG5 precipitation weather phenomenon instruments have been installed in a large number of domestic stations, and a great deal of valuable data have been observed and recorded. This paper analyzes the data structure, content and application of the DSG5 precipitation weather phenomenon instrument data through a precipitation weather process. The analysis finds that the precipitation start time judged by the DSG5 precipitation weather phenomenon instrument is later than the actual, and the end time of precipitation is earlier than the actual, and some weak precipitation cannot be judged; the raindrop spectrum data can reveal the fine structure and evolution characteristics of the precipitation process, deepen the understanding of the precipitation process, and help to accurately and intuitively deal with the problem of the mismatch between precipitation and weather phenomena in automatic meteorological observations. From the raindrop spectrum data, there are many small raindrops with a diameter of about 0.3 mm in the precipitation process, but the raindrops with a diameter of more than 1 mm have the larger impact on precipitation intensity. With the increase of raindrops with a diameter of more than 1 mm, the ground precipitation increases significantly.
2021, 49(1):46-54.
Abstract:
It is very important to analyze and test the data of the TK2GPS sounding rocket for understanding the applicability and the data reliability of the test instrument and its application prospects in weather modification. Based on the analysis methods of average deviation (BIAS), root mean square error (RMSE), and correlation coefficient, usging the TK2GPS sounding rocket and Lband sounding radar data, the differences and variation characteristics of the sounding data such as temperature, relative humidity, wind direction and wind speed are compared and analyzed, and the possible causes of the differences are discussed. The results show that the TK2 GPS sounding rocket and the Lband sounding have significant positive correlations with the same elements, and passed the significance test of 0.05 and above. Analyses of the differences between the two sounding data reveal that the average deviation and dispersion of temperature and wind speed are small; although the average deviation of relative humidity is large, correlation is good; the dispersion of wind direction at each level is large, and the correlation is poor. The vertical profiles of temperature and wind speed of the two soundings are highly consistent. The vertical profile of relative humidity is significantly different at low altitudes and more consistent at higher altitudes; the relative humidity at low altitudes is greater than that at high altitudes. The difference trend in wind profiles is just the opposite of relative humidity profiles. With the increase of horizontal detection distance, the deviation of each element of sounding rocket from Lband sounding increases. The correction equation of relative humidity is established by correlation analysis. It can correct the relative humidity of sounding rockets very well.
It is very important to analyze and test the data of the TK2GPS sounding rocket for understanding the applicability and the data reliability of the test instrument and its application prospects in weather modification. Based on the analysis methods of average deviation (BIAS), root mean square error (RMSE), and correlation coefficient, usging the TK2GPS sounding rocket and Lband sounding radar data, the differences and variation characteristics of the sounding data such as temperature, relative humidity, wind direction and wind speed are compared and analyzed, and the possible causes of the differences are discussed. The results show that the TK2 GPS sounding rocket and the Lband sounding have significant positive correlations with the same elements, and passed the significance test of 0.05 and above. Analyses of the differences between the two sounding data reveal that the average deviation and dispersion of temperature and wind speed are small; although the average deviation of relative humidity is large, correlation is good; the dispersion of wind direction at each level is large, and the correlation is poor. The vertical profiles of temperature and wind speed of the two soundings are highly consistent. The vertical profile of relative humidity is significantly different at low altitudes and more consistent at higher altitudes; the relative humidity at low altitudes is greater than that at high altitudes. The difference trend in wind profiles is just the opposite of relative humidity profiles. With the increase of horizontal detection distance, the deviation of each element of sounding rocket from Lband sounding increases. The correction equation of relative humidity is established by correlation analysis. It can correct the relative humidity of sounding rockets very well.
2021, 49(1):55-62.
Abstract:
Clouds are an important part of the earth system, which can affect the radiation balance of the earthatmosphere system by affecting atmospheric radiation transmission. At present, the information obtained from threedimensional cloud observation has certain limitations, so it is necessary to obtain more accurate threedimensional cloud information by using multisource observation data merging analysis. Based on the successive correction method, 〖JP2〗the ThreeDimensional Cloud Merge Analysis Operation System (3DCloudAV1.0) integrates multisource data such as numerical forecast products, geostationary meteorological satellite observation, meteorological radar observation to produce the realtime 0.05°/h threedimensional cloud merging analysis product covering China and its surrounding areas (0°-60°N, 70°-140°E), which is distributed to the national and provincial meteorological departments through the China Telecommunication System. The modular system framework is considered in the operation system design and construction process, and the fault tolerant functions such as ECFlow scheduling process realtime monitoring and automatic restarting are developed, which effectively improves the stability and reliability of the operation system. Evaluations show that through merging multisource observation data, the threedimensional cloud merge analysis product can describe cloud the top, inside and bottom information more accurately.〖JP〗
Clouds are an important part of the earth system, which can affect the radiation balance of the earthatmosphere system by affecting atmospheric radiation transmission. At present, the information obtained from threedimensional cloud observation has certain limitations, so it is necessary to obtain more accurate threedimensional cloud information by using multisource observation data merging analysis. Based on the successive correction method, 〖JP2〗the ThreeDimensional Cloud Merge Analysis Operation System (3DCloudAV1.0) integrates multisource data such as numerical forecast products, geostationary meteorological satellite observation, meteorological radar observation to produce the realtime 0.05°/h threedimensional cloud merging analysis product covering China and its surrounding areas (0°-60°N, 70°-140°E), which is distributed to the national and provincial meteorological departments through the China Telecommunication System. The modular system framework is considered in the operation system design and construction process, and the fault tolerant functions such as ECFlow scheduling process realtime monitoring and automatic restarting are developed, which effectively improves the stability and reliability of the operation system. Evaluations show that through merging multisource observation data, the threedimensional cloud merge analysis product can describe cloud the top, inside and bottom information more accurately.〖JP〗
2021, 49(1):63-68.
Abstract:
The high performance computing cluster in the Northwest Regional Meteorological Center uses the job scheduling software LoadLeveler to schedule and manage jobs, in order to realize the maximization of resource utilization and throughput. This paper studies and discusses the role and method of scheduling management job. Defining the queue through the configuration file keywords, setting the scheduling algorithm and scheduler adjustment parameters, matching the processing requirements of the job with the available resources, 〖JP2〗the availability rules of clusters and various resources are defined according to actual requirements, so as to prevent the mutual interference between jobs. Combined with the LoadLeveler job preemption function, the regional numerical weather prediction business model is guaranteed to have the priority and stable operation. Perl language is used to write a script to account the resources of the high performance computer cluster, so that the administrator can fully grasp the use of resources of various application modes, reasonably adjust the system resource allocation and scheduling strategy, and give full play to the benefits of the high performance computer cluster in the Northwest Regional Meteorological Center.〖JP〗
The high performance computing cluster in the Northwest Regional Meteorological Center uses the job scheduling software LoadLeveler to schedule and manage jobs, in order to realize the maximization of resource utilization and throughput. This paper studies and discusses the role and method of scheduling management job. Defining the queue through the configuration file keywords, setting the scheduling algorithm and scheduler adjustment parameters, matching the processing requirements of the job with the available resources, 〖JP2〗the availability rules of clusters and various resources are defined according to actual requirements, so as to prevent the mutual interference between jobs. Combined with the LoadLeveler job preemption function, the regional numerical weather prediction business model is guaranteed to have the priority and stable operation. Perl language is used to write a script to account the resources of the high performance computer cluster, so that the administrator can fully grasp the use of resources of various application modes, reasonably adjust the system resource allocation and scheduling strategy, and give full play to the benefits of the high performance computer cluster in the Northwest Regional Meteorological Center.〖JP〗
2021, 49(1):69-76.
Abstract:
This paper analyzes the climatic characteristics of the tropical cyclone (TC) centers that entered the range of 10°×10° (longitude×latitude) around Yongxing Island from 1958 to 2019. The results show that the Yongxing Island is influenced averagely by 9.4 TCs in a year, and the TCs show a significant (α=0.01) decreasing trend in 0.67 every decade (an trend coefficient of -0.406). This paper divides the TC paths in Yongxing Island into five categories: northwestward moving (A), southwestward moving (B), northeastward turning (C), southwestward turning (D), northeastward turning from west (E), of which Type A accounts for 52.0%. The annual rainfall caused by TCs exhibits a significant (α=0.05) decreasing trend (an regression coefficient of -61.76, an trend coefficient of -0.27). TC activities contribute the most to the heavy rainfall of Yongxing Island, reaching 67.8%, while the contribution of other weather systems is only 32.2%. The annual average number of rain days caused by typhoon is 4.1, while that caused by the others is 2.8 days. The contribution of Typhoon Rainstorms to annual storm rainfall shows no obvious variation trend (an regression coefficient of 0.57, an trend coefficient of 0.055), but the contribution of typhoon rainstorm days to annual rainstorm days shows a significant (α=0.01) decreasing trend (a regression coefficient of 4.7, a trend coefficient of -0.33).
This paper analyzes the climatic characteristics of the tropical cyclone (TC) centers that entered the range of 10°×10° (longitude×latitude) around Yongxing Island from 1958 to 2019. The results show that the Yongxing Island is influenced averagely by 9.4 TCs in a year, and the TCs show a significant (α=0.01) decreasing trend in 0.67 every decade (an trend coefficient of -0.406). This paper divides the TC paths in Yongxing Island into five categories: northwestward moving (A), southwestward moving (B), northeastward turning (C), southwestward turning (D), northeastward turning from west (E), of which Type A accounts for 52.0%. The annual rainfall caused by TCs exhibits a significant (α=0.05) decreasing trend (an regression coefficient of -61.76, an trend coefficient of -0.27). TC activities contribute the most to the heavy rainfall of Yongxing Island, reaching 67.8%, while the contribution of other weather systems is only 32.2%. The annual average number of rain days caused by typhoon is 4.1, while that caused by the others is 2.8 days. The contribution of Typhoon Rainstorms to annual storm rainfall shows no obvious variation trend (an regression coefficient of 0.57, an trend coefficient of 0.055), but the contribution of typhoon rainstorm days to annual rainstorm days shows a significant (α=0.01) decreasing trend (a regression coefficient of 4.7, a trend coefficient of -0.33).
2021, 49(1):77-85.
Abstract:
Based on the high spatial and temporal resolution (0.125°×0.125°) reanalysis data of ERAInterim issued by the European Centre for MediumRange Weather Forecasts (ECMWF) and the precipitation observation data of the meteorological stations from 1989 to 2018, the characteristics of precipitation and air water vapor conditions on the east and west slopes of Liupan Mountain in recent 30 years are analyzed. The results show that: (1) The spatial distribution characteristics of the atmospheric precipitation, 700 hPa specific humidity and water vapor flux in the Liupan mountain area are relatively consistent with these of the precipitation in recent 30 years, with the characteristics of high in the east and low in the west, large in the south and small in the north. (2) During the summer main precipitation processes， the water vapor in the Liupan mountain area mainly comes from the lower layer of the Bay of Bengal, South China Sea and Indian Ocean. (3) The water vapor transport characteristics over the Liupan Mountain area are as follows: the water vapor transport is dominated by the southwest wind in 700 hPa and 750 hPa; the east side of the Liupan Mountain is the windward slope of the southeast wind below 750 hPa; influenced by the landform forcing, the southeast warm and wet air flow rises on the east slope. (4) The divergence field of water vapor flux has a structure of divergence at upper levels and convergence or weak divergence at lower levels over the eastern slope of the Liupan Mountain. Combined with the interaction of topography, East Asian monsoon, and various weather systems, the distribution characteristics of precipitation and air water vapor conditions in the Liupan mountain area are high in the east and low in the west. The preliminary results can reveal the characteristics of regional air water vapor conditions and provide a reference basis for the development of cloud water resources.
Based on the high spatial and temporal resolution (0.125°×0.125°) reanalysis data of ERAInterim issued by the European Centre for MediumRange Weather Forecasts (ECMWF) and the precipitation observation data of the meteorological stations from 1989 to 2018, the characteristics of precipitation and air water vapor conditions on the east and west slopes of Liupan Mountain in recent 30 years are analyzed. The results show that: (1) The spatial distribution characteristics of the atmospheric precipitation, 700 hPa specific humidity and water vapor flux in the Liupan mountain area are relatively consistent with these of the precipitation in recent 30 years, with the characteristics of high in the east and low in the west, large in the south and small in the north. (2) During the summer main precipitation processes， the water vapor in the Liupan mountain area mainly comes from the lower layer of the Bay of Bengal, South China Sea and Indian Ocean. (3) The water vapor transport characteristics over the Liupan Mountain area are as follows: the water vapor transport is dominated by the southwest wind in 700 hPa and 750 hPa; the east side of the Liupan Mountain is the windward slope of the southeast wind below 750 hPa; influenced by the landform forcing, the southeast warm and wet air flow rises on the east slope. (4) The divergence field of water vapor flux has a structure of divergence at upper levels and convergence or weak divergence at lower levels over the eastern slope of the Liupan Mountain. Combined with the interaction of topography, East Asian monsoon, and various weather systems, the distribution characteristics of precipitation and air water vapor conditions in the Liupan mountain area are high in the east and low in the west. The preliminary results can reveal the characteristics of regional air water vapor conditions and provide a reference basis for the development of cloud water resources.
2021, 49(1):86-94.
Abstract:
A widerange disastrous supercell hailstorm occurred in Zhejiang Province on 21 March 2019 is simulated by using the highresolution mesoscale WRF model. Combined with Doppler radar detection products, the characteristics of radar echo structure, flow field structure, hydrometeors and their evolutions are analyzed, and the physical mechanism of hail formation is explored. The results show that the hailstorm occurred and developed in the area where the right side of the highlevel jet axis overlapped with the lowlevel shear line. Strong vertical wind shear contributes to its maintenance and development. The supercell hailstorm exhibits typical characteristics of hook echo, longlasting deep mesocyclone, strong hanging echo, bounded weak echo area, and strong threebody scattering on radar echoes. The simulation experiment successfully simulated the horizontal evolution and vertical structure of the hailstorm clouds. Suitable layer heights of 0 ℃ and -20 ℃， as well as an appropriate thickness of the 0 ℃ to -20 ℃ layer, are conducive to the growth of hail particles. Hail particles are mainly transformed from cloud water, supercooled rain water and snow particles and then continue to grow by collisioncoalescing with supercooled cloud water, ice crystals and snow particles.
A widerange disastrous supercell hailstorm occurred in Zhejiang Province on 21 March 2019 is simulated by using the highresolution mesoscale WRF model. Combined with Doppler radar detection products, the characteristics of radar echo structure, flow field structure, hydrometeors and their evolutions are analyzed, and the physical mechanism of hail formation is explored. The results show that the hailstorm occurred and developed in the area where the right side of the highlevel jet axis overlapped with the lowlevel shear line. Strong vertical wind shear contributes to its maintenance and development. The supercell hailstorm exhibits typical characteristics of hook echo, longlasting deep mesocyclone, strong hanging echo, bounded weak echo area, and strong threebody scattering on radar echoes. The simulation experiment successfully simulated the horizontal evolution and vertical structure of the hailstorm clouds. Suitable layer heights of 0 ℃ and -20 ℃， as well as an appropriate thickness of the 0 ℃ to -20 ℃ layer, are conducive to the growth of hail particles. Hail particles are mainly transformed from cloud water, supercooled rain water and snow particles and then continue to grow by collisioncoalescing with supercooled cloud water, ice crystals and snow particles.
2021, 49(1):95-106.
Abstract:
On 10 June 2011 (for short, Process 1106) and on 10 June 2017 (Process 1706), there occurred two rainstorms in the south of Jiangsu Province. With the conventional observational and FNL reanalysis data and radar data, the two processes are analyzed. The results show that the anomalous high and low latitudinal circulation conditions provided a favorable circulation background for the occurrence of the heavy precipitation. There were great differences between the two processes in the physical quantity fields of the representative stations: the maximum divergence of Process 1706 was about twice as big as that of Process 1106; the maximum vertical velocity and maximum water vapor flux divergence of Process 1706 were about 1.8 and 1.3 times as big as that of Process 1106; and the large values were maintained for a long time. Both processes were characterized by strong tropical precipitation in the warm region; but the strong echo of 1106 was dispersing, the extensional height was low, the intensity was weak, and there was no obvious “train effect” of strong echoes. The strong echoes of Process 1706 arranged closely; the extension height was high, the intensity was obviously strong; and the “train effect” of strong echo was obvious. The change of helicity was generally ahead of that of precipitation, which was predictable and can be used as a predictor of the start, maintenance, and ending of largearea precipitation in shorttime forecasting (nowcasting). The change of the bottom height of the high wind zone in VWP (Vertical Wind Profiles) products was helpful to judge the changing trend of precipitation around the radar station.
On 10 June 2011 (for short, Process 1106) and on 10 June 2017 (Process 1706), there occurred two rainstorms in the south of Jiangsu Province. With the conventional observational and FNL reanalysis data and radar data, the two processes are analyzed. The results show that the anomalous high and low latitudinal circulation conditions provided a favorable circulation background for the occurrence of the heavy precipitation. There were great differences between the two processes in the physical quantity fields of the representative stations: the maximum divergence of Process 1706 was about twice as big as that of Process 1106; the maximum vertical velocity and maximum water vapor flux divergence of Process 1706 were about 1.8 and 1.3 times as big as that of Process 1106; and the large values were maintained for a long time. Both processes were characterized by strong tropical precipitation in the warm region; but the strong echo of 1106 was dispersing, the extensional height was low, the intensity was weak, and there was no obvious “train effect” of strong echoes. The strong echoes of Process 1706 arranged closely; the extension height was high, the intensity was obviously strong; and the “train effect” of strong echo was obvious. The change of helicity was generally ahead of that of precipitation, which was predictable and can be used as a predictor of the start, maintenance, and ending of largearea precipitation in shorttime forecasting (nowcasting). The change of the bottom height of the high wind zone in VWP (Vertical Wind Profiles) products was helpful to judge the changing trend of precipitation around the radar station.
2021, 49(1):107-113.
Abstract:
Based on the winter precipitation data from 20 weather stations, the conventional observation data and the new generation weather radar (CINRAD/SA) data in Beijing from 2001 to 2018, the climate, the circulation situations and the radar echo characteristics of 16 snowstorm events are analyzed. The results indicate that there are four circulation patterns for snowstorms in Beijing: low vortex and low trough, surface inverse trough, transversal trough, and circumfluence. The snowstorms in Beijing can be generally divided into the mixed type and the stratiform cloud type according to the echo type, in which the mixed type accounts for the majority, with a sliceflocculent echo shape, a maximum reflectivity factor of greater than 35 dBz and an echo top height of greater than 4 km. In the radial velocity field, there exists a bulleye structure in most of snowstorm events in Beijing, all of which are boundary layer lowlevel jets. The existence of the lowlevel jets is very important for the generation and maintenance of snowstorms. The results can be used as a reference for operational forecasting of winter snowstorms.
Based on the winter precipitation data from 20 weather stations, the conventional observation data and the new generation weather radar (CINRAD/SA) data in Beijing from 2001 to 2018, the climate, the circulation situations and the radar echo characteristics of 16 snowstorm events are analyzed. The results indicate that there are four circulation patterns for snowstorms in Beijing: low vortex and low trough, surface inverse trough, transversal trough, and circumfluence. The snowstorms in Beijing can be generally divided into the mixed type and the stratiform cloud type according to the echo type, in which the mixed type accounts for the majority, with a sliceflocculent echo shape, a maximum reflectivity factor of greater than 35 dBz and an echo top height of greater than 4 km. In the radial velocity field, there exists a bulleye structure in most of snowstorm events in Beijing, all of which are boundary layer lowlevel jets. The existence of the lowlevel jets is very important for the generation and maintenance of snowstorms. The results can be used as a reference for operational forecasting of winter snowstorms.
2021, 49(1):114-123.
Abstract:
The uncertainty of the satellite precipitation products limits their applicability in complex terrain areas. This paper evaluates the applicability of the new rainfall products, GPM （Global Precipitation Measurement） IMERG （Integrated MultisatellitE Retrievals for GPM） and ERA5 precipitation in Yunnan Province area based on the meteorological data. The data of a total of 125 weather stations from April 2014 to June 2018 are used to evaluate and compare the accuracies of GPM IMERG and ERA5. The correlation coefficient (R), root mean square error (RMSE), relative bias (BIAS), Mean Absolute Error (MAE) and the classification statistical analysis indexes (POD, FAR, CIS) are used to assess the applicability of GPM IMERG and ERA5. The result shows that: The two kinds of data have the problems of overestimation of daily precipitation of light rainfall and underestimation of daily precipitation of moderate and above rainfall, and ERA5 data is more prominent in this respect. GPM IMERG data have both higher false and missing alarm rates, while ERA5 data have seriously higher and lower missing rate, especially in light rain days. The areas with more (less) light rain days are in good agreement with the two areas with higher missing (false) rates. In autumn, the precipitation data accuracy of GPM IMERG is the highest in different rain intensity ranges. In winter, there are different performances: underestimation of low rain intensity and overestimation of high rain intensity. For the medium and low rainfall intensity of below 20 mm/d, the errors between the two precipitation data and ground station data are relatively small, and the errors increase with the increasing rain intensity. When the rain intensity is greater than 20 mm/d, the difference between the two data and the station increases more significantly with the increasing rain intensity. With the increase of slope and fluctuation, the accuracy of two kinds of precipitation data presents a trend of deterioration. The evaluation indexes show that GPM IMERG precipitation data have higher accuracy in Yunnan. The research results provide a reference for the application and development of agriculture, water conservancy, hydrology, meteorology and other related disciplines.
The uncertainty of the satellite precipitation products limits their applicability in complex terrain areas. This paper evaluates the applicability of the new rainfall products, GPM （Global Precipitation Measurement） IMERG （Integrated MultisatellitE Retrievals for GPM） and ERA5 precipitation in Yunnan Province area based on the meteorological data. The data of a total of 125 weather stations from April 2014 to June 2018 are used to evaluate and compare the accuracies of GPM IMERG and ERA5. The correlation coefficient (R), root mean square error (RMSE), relative bias (BIAS), Mean Absolute Error (MAE) and the classification statistical analysis indexes (POD, FAR, CIS) are used to assess the applicability of GPM IMERG and ERA5. The result shows that: The two kinds of data have the problems of overestimation of daily precipitation of light rainfall and underestimation of daily precipitation of moderate and above rainfall, and ERA5 data is more prominent in this respect. GPM IMERG data have both higher false and missing alarm rates, while ERA5 data have seriously higher and lower missing rate, especially in light rain days. The areas with more (less) light rain days are in good agreement with the two areas with higher missing (false) rates. In autumn, the precipitation data accuracy of GPM IMERG is the highest in different rain intensity ranges. In winter, there are different performances: underestimation of low rain intensity and overestimation of high rain intensity. For the medium and low rainfall intensity of below 20 mm/d, the errors between the two precipitation data and ground station data are relatively small, and the errors increase with the increasing rain intensity. When the rain intensity is greater than 20 mm/d, the difference between the two data and the station increases more significantly with the increasing rain intensity. With the increase of slope and fluctuation, the accuracy of two kinds of precipitation data presents a trend of deterioration. The evaluation indexes show that GPM IMERG precipitation data have higher accuracy in Yunnan. The research results provide a reference for the application and development of agriculture, water conservancy, hydrology, meteorology and other related disciplines.
2021, 49(1):124-130.
Abstract:
According to the temperature and precipitation data observed by 72 national meteorological stations from 1961 to 2005 and simulated by the regional climate model CCLM from 1961 to 2005 in the Yellow River Basin of Inner Mongolia, the BP neural network model is used to predict and analyze the runoff changes in the Toudaoguai hydrological station under three RCP scenarios from 2011 to 2100, so to evaluate the possible impact of future climate change on water resources in the basin. The results show that: (1) From 2011 to 2100, the temperature in the Yellow River Basin of Inner Mongolia would increase, but the precipitation would not change significantly, and the annual average runoff show a decreasing trend. Corresponding to the scenarios of RCP2.6, RCP4.5, and RCP8.5, the decrease would be by 3.6%, 2.7% and 23.4%, respectively. (2) In the future, the spring runoff would mainly increase; in summer, the trends of runoff change in different scenarios would be inconsistent; in autumn, the runoff would mainly increase before the 2050s and then decrease mainly; in winter, the runoff would mainly decrease. (3) In the future, the available water resources in the basin would decrease, and especially the contradiction between supply and demand of water resources would intensify in summer. The seasonal distribution of runoff would change, which might result in greater spring runoff.
According to the temperature and precipitation data observed by 72 national meteorological stations from 1961 to 2005 and simulated by the regional climate model CCLM from 1961 to 2005 in the Yellow River Basin of Inner Mongolia, the BP neural network model is used to predict and analyze the runoff changes in the Toudaoguai hydrological station under three RCP scenarios from 2011 to 2100, so to evaluate the possible impact of future climate change on water resources in the basin. The results show that: (1) From 2011 to 2100, the temperature in the Yellow River Basin of Inner Mongolia would increase, but the precipitation would not change significantly, and the annual average runoff show a decreasing trend. Corresponding to the scenarios of RCP2.6, RCP4.5, and RCP8.5, the decrease would be by 3.6%, 2.7% and 23.4%, respectively. (2) In the future, the spring runoff would mainly increase; in summer, the trends of runoff change in different scenarios would be inconsistent; in autumn, the runoff would mainly increase before the 2050s and then decrease mainly; in winter, the runoff would mainly decrease. (3) In the future, the available water resources in the basin would decrease, and especially the contradiction between supply and demand of water resources would intensify in summer. The seasonal distribution of runoff would change, which might result in greater spring runoff.
2021, 49(1):131-138.
Abstract:
Based on the gale data of Hangzhou National Base Station from 1951 to 2018 and the maximum wind speed data of 373 automatic meteorological stations after the quality control from 2014 to 2018, to provide suggestions on agricultural development, the MK method and GIS mapping technology are used to analyze the interannual variation of strong winds since the establishment of Hangzhou Station and the spatial distribution characteristics of different wind levels in recent five years, combined with the wind disaster grade index of single steelframe greenhouses and the townlevel data of the third agricultural census. The results show that the number of strongwind days in the year of severe disasters in the greenhouses decreases fluctuationally, and a sudden change happened in 2001, with a more obvious downward trend, and the changes in various seasons are similar. As a result, the areas where the greenhouses suffered from the light, medium and heavy wind disasters are in the northwestern Linan, Anding Mountain of Fuyang and the Hangzhou Bay in the northeastern Zhejiang Province. The Hangzhou Bay area is also the main development area of facility agriculture, which requires higher construction standards. The central area of Hangzhou is the low value area of high wind, which is conducive to the further development of facility agriculture. The number of days and times of serve wind disasters causing moderate to severe wind disasters in singlesteel frame greenhouses are the highest in summer, followed by spring, and the least in autumn, with the longest duration in winter, followed by autumn and the shortest in spring.
Based on the gale data of Hangzhou National Base Station from 1951 to 2018 and the maximum wind speed data of 373 automatic meteorological stations after the quality control from 2014 to 2018, to provide suggestions on agricultural development, the MK method and GIS mapping technology are used to analyze the interannual variation of strong winds since the establishment of Hangzhou Station and the spatial distribution characteristics of different wind levels in recent five years, combined with the wind disaster grade index of single steelframe greenhouses and the townlevel data of the third agricultural census. The results show that the number of strongwind days in the year of severe disasters in the greenhouses decreases fluctuationally, and a sudden change happened in 2001, with a more obvious downward trend, and the changes in various seasons are similar. As a result, the areas where the greenhouses suffered from the light, medium and heavy wind disasters are in the northwestern Linan, Anding Mountain of Fuyang and the Hangzhou Bay in the northeastern Zhejiang Province. The Hangzhou Bay area is also the main development area of facility agriculture, which requires higher construction standards. The central area of Hangzhou is the low value area of high wind, which is conducive to the further development of facility agriculture. The number of days and times of serve wind disasters causing moderate to severe wind disasters in singlesteel frame greenhouses are the highest in summer, followed by spring, and the least in autumn, with the longest duration in winter, followed by autumn and the shortest in spring.
2021, 49(1):139-143.
Abstract:
Compared with the traditional weather radar, the hardware of the dual polarization weather radar has changed greatly, especially in the receiver and antenna feeder. The change of hardware makes the diagnosis method of dual polarization radar different. This paper analyzes the difference between Sband dual polarization weather radar and single polarization radar in fault diagnosis by comparing with traditional weather radar in hardware structure and calibration channel. This article proposes two diagnostic techniques: isolating the main channel and test channel by the dual signal source and dynamic method; segmenting the main channel by the dual signal source and sun calibration. The article gives the fault cases of dual polarization radar, which can provide a reference for the planned upgrading of the dual polarization radar, and also provide a reference for the troubleshooting of the dual polarization radar at the radar stations.
Compared with the traditional weather radar, the hardware of the dual polarization weather radar has changed greatly, especially in the receiver and antenna feeder. The change of hardware makes the diagnosis method of dual polarization radar different. This paper analyzes the difference between Sband dual polarization weather radar and single polarization radar in fault diagnosis by comparing with traditional weather radar in hardware structure and calibration channel. This article proposes two diagnostic techniques: isolating the main channel and test channel by the dual signal source and dynamic method; segmenting the main channel by the dual signal source and sun calibration. The article gives the fault cases of dual polarization radar, which can provide a reference for the planned upgrading of the dual polarization radar, and also provide a reference for the troubleshooting of the dual polarization radar at the radar stations.
2021, 49(1):144-147.
Abstract:
In order to meet 〖JP2〗the demands of a realtime automatic ground meteorological monitoring as well as an adaption to more intensive, standardized and intelligent meteorological observation, the Meteorological Observation Centre of CMA (China Meteorological Administration) has built a business prototype station at Beijing Observatory, which represents the future development of automatic ground meteorological observation. The system uses the mature and stable technology in electronic measurement, data transmission and control technology, has high reliability and high accuracy, is easy to maintain and extend. The system supports the ground meteorological data object dictionary protocol format, and the realtime observation data is sent to the ZigBee coordinator by the ZigBee wireless data transmission module. With the employment of the integrated surface observation system, the station observation data collected by an integrated hardware controller realize the quality control and application of automatically observed data.
In order to meet 〖JP2〗the demands of a realtime automatic ground meteorological monitoring as well as an adaption to more intensive, standardized and intelligent meteorological observation, the Meteorological Observation Centre of CMA (China Meteorological Administration) has built a business prototype station at Beijing Observatory, which represents the future development of automatic ground meteorological observation. The system uses the mature and stable technology in electronic measurement, data transmission and control technology, has high reliability and high accuracy, is easy to maintain and extend. The system supports the ground meteorological data object dictionary protocol format, and the realtime observation data is sent to the ZigBee coordinator by the ZigBee wireless data transmission module. With the employment of the integrated surface observation system, the station observation data collected by an integrated hardware controller realize the quality control and application of automatically observed data.
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.