Volume 47,Issue 2,2019 Table of Contents
2019, 47(2):191-200.
Abstract:
Because of the low spatial resolution of the conventional ground meteorological observation network in Sichuan and the lack of data representativeness, the vertical cloud structure and the microphysical conditions in clouds cannot be obtained completely. In view of this, a series of scientific observation experiments for largerange cloud systems have been conducted in Sichuan since 2014. Observed objects are mainly stratiform clouds and stratified mixed clouds with embedded convection in Sichuan Basin and cumuliform clouds (convective clouds). This paper addresses six aspects of the scientific experiments, such as the objectives, regions, observation elements, observation layout design, observation scheme design and equipment technology， emphasizing the ideas of the observation layout design. According to different types of cloud systems and characteristics of precipitation variation, we have designed a tailored observational scheme, thus having obtained the continuous multiscale observation data of different types of cloud systems and precipitation. The series of scientific observation experiments provide data support for revealing the multiscale structural characteristics and the evolution way of the largerange cloud systems and precipitation in Sichuan and discussing the mechanisms of the occurrence, development and microphysical processes of cloud systems and precipitation.
Because of the low spatial resolution of the conventional ground meteorological observation network in Sichuan and the lack of data representativeness, the vertical cloud structure and the microphysical conditions in clouds cannot be obtained completely. In view of this, a series of scientific observation experiments for largerange cloud systems have been conducted in Sichuan since 2014. Observed objects are mainly stratiform clouds and stratified mixed clouds with embedded convection in Sichuan Basin and cumuliform clouds (convective clouds). This paper addresses six aspects of the scientific experiments, such as the objectives, regions, observation elements, observation layout design, observation scheme design and equipment technology， emphasizing the ideas of the observation layout design. According to different types of cloud systems and characteristics of precipitation variation, we have designed a tailored observational scheme, thus having obtained the continuous multiscale observation data of different types of cloud systems and precipitation. The series of scientific observation experiments provide data support for revealing the multiscale structural characteristics and the evolution way of the largerange cloud systems and precipitation in Sichuan and discussing the mechanisms of the occurrence, development and microphysical processes of cloud systems and precipitation.
2019, 47(2):201-206.
Abstract:
In order to improve the system phase noise and ground clutter suppression capability, Burst technology was modified for some domestic CINRAD/SA weather radars to reduce and eliminate the influence of phase jitter of the transmitted signals. To test the improvement of phase noise and ground clutter suppression ability of CINRAD/SA weather radar after Burst technical transformation, the theoretical analysis, performance test and echo data analysis are used to test the capability. The test results show that the phase noise of the CINRAD/SA weather radar system is reduced by about 0.05° after the Burst technical transformation, and the ground clutter suppression capability is improved by more than 55 dB. The phase noise and ground clutter suppression capability are improved obviously, and can be used as a good reference for other models of weather radar.
In order to improve the system phase noise and ground clutter suppression capability, Burst technology was modified for some domestic CINRAD/SA weather radars to reduce and eliminate the influence of phase jitter of the transmitted signals. To test the improvement of phase noise and ground clutter suppression ability of CINRAD/SA weather radar after Burst technical transformation, the theoretical analysis, performance test and echo data analysis are used to test the capability. The test results show that the phase noise of the CINRAD/SA weather radar system is reduced by about 0.05° after the Burst technical transformation, and the ground clutter suppression capability is improved by more than 55 dB. The phase noise and ground clutter suppression capability are improved obviously, and can be used as a good reference for other models of weather radar.
2019, 47(2):207-213.
Abstract:
In this study, we evaluate the detection sensitivity， ground clutter suppression performance and the quality of polarimetric parameters, including differential reflectivity (ZDR), differential phase shift (〖WTBX〗Φ〖WTBZ〗DP), specific differential phase (KDP) and correlation coefficient, based on the Sband Dualpolarimetric radar of Guangzhou. The results show that the detection sensitivity retain the fine qualities and the effect of ground clutter suppression has been greatly improved after the upgrading; 〖WTBX〗Z〖WTBZ〗DR has a stable systematic bias not exceeding 0.2 dB, increasing with 〖WTBX〗Z〖WTBZ〗 in agreement with to the empirical value. The initial phase of〖WTBX〗 Φ〖WTBZ〗DP shows good stability, and 〖WTBX〗K〖WTBZ〗DP is sensitive to precipitation, especially corresponding well to heavy rainfall. Correlation coefficient can be used to divide successfully meteorological and nonmeteorological targets.
In this study, we evaluate the detection sensitivity， ground clutter suppression performance and the quality of polarimetric parameters, including differential reflectivity (ZDR), differential phase shift (〖WTBX〗Φ〖WTBZ〗DP), specific differential phase (KDP) and correlation coefficient, based on the Sband Dualpolarimetric radar of Guangzhou. The results show that the detection sensitivity retain the fine qualities and the effect of ground clutter suppression has been greatly improved after the upgrading; 〖WTBX〗Z〖WTBZ〗DR has a stable systematic bias not exceeding 0.2 dB, increasing with 〖WTBX〗Z〖WTBZ〗 in agreement with to the empirical value. The initial phase of〖WTBX〗 Φ〖WTBZ〗DP shows good stability, and 〖WTBX〗K〖WTBZ〗DP is sensitive to precipitation, especially corresponding well to heavy rainfall. Correlation coefficient can be used to divide successfully meteorological and nonmeteorological targets.
2019, 47(2):214-221.
Abstract:
Based on the wind field data of 19 stations in Shanghai coastal waters in 2016, the wind field quality control methods are studied, including the integrity check, internal consistency check, continuity check, and height correction. Meanwhile, 10 stations are selected as observation stations of the wind field forecast verification in 2016, including wind speed error, wind speed accuracy and wind direction verification, and compared the results before and after the quality control of the wind field observation data. Finally, two strong wind processes are verified. The main results are as follow: the forecast verification results become worse with the increase of forecast time; the overall error of wind speed forecast in autumn and winter is small, and that in June and July is larger; the accuracy rate of the 0-5 level wind speed verification is between 0.9 and 1, and the forecast value is larger than observation; the accuracy rate of wind speed forecast above level 6 is gradually reduced, and the forecast value is smaller than that of observation. The wind direction verification shows obvious seasonality; in December and January, the error is small and the accuracy rate is the highest; in June, the error is the largest and the accuracy rate is the lowest. After quality control, the verification results are improved positively; the accuracy rates of the two strong wind processes are all above 70%.
Based on the wind field data of 19 stations in Shanghai coastal waters in 2016, the wind field quality control methods are studied, including the integrity check, internal consistency check, continuity check, and height correction. Meanwhile, 10 stations are selected as observation stations of the wind field forecast verification in 2016, including wind speed error, wind speed accuracy and wind direction verification, and compared the results before and after the quality control of the wind field observation data. Finally, two strong wind processes are verified. The main results are as follow: the forecast verification results become worse with the increase of forecast time; the overall error of wind speed forecast in autumn and winter is small, and that in June and July is larger; the accuracy rate of the 0-5 level wind speed verification is between 0.9 and 1, and the forecast value is larger than observation; the accuracy rate of wind speed forecast above level 6 is gradually reduced, and the forecast value is smaller than that of observation. The wind direction verification shows obvious seasonality; in December and January, the error is small and the accuracy rate is the highest; in June, the error is the largest and the accuracy rate is the lowest. After quality control, the verification results are improved positively; the accuracy rates of the two strong wind processes are all above 70%.
2019, 47(2):222-228.
Abstract:
Prevailing visibility is an important parameter of normal civil aviation activities. It has obvious practical significance along with the increasing constructions of general aviation airport. In consideration of the existing visibility meters in a single aerodrome, we use three methods to calculate the airport prevailing visibility: median method, graph proportion method and averaging method. We use the existing multiset visibility sensors at the airport to conduct automatic observation of prevailing visibility and use the three methods to study and analyze the multivisibility sensor measurements at daytime and nighttime in Tianjin, Dalian, Hailar, Chengdu and Chongqing for 100 consecutive days. After qualitative and quantitative analysis and comparison, the averaging method is proved to have less measuring error than that of the median method and graph proportion method. The differences in observation principles and observation methods, the number of visibility meters, regional climate, and observation locations are the main factors affecting the data quality of prevailing visibility.
Prevailing visibility is an important parameter of normal civil aviation activities. It has obvious practical significance along with the increasing constructions of general aviation airport. In consideration of the existing visibility meters in a single aerodrome, we use three methods to calculate the airport prevailing visibility: median method, graph proportion method and averaging method. We use the existing multiset visibility sensors at the airport to conduct automatic observation of prevailing visibility and use the three methods to study and analyze the multivisibility sensor measurements at daytime and nighttime in Tianjin, Dalian, Hailar, Chengdu and Chongqing for 100 consecutive days. After qualitative and quantitative analysis and comparison, the averaging method is proved to have less measuring error than that of the median method and graph proportion method. The differences in observation principles and observation methods, the number of visibility meters, regional climate, and observation locations are the main factors affecting the data quality of prevailing visibility.
2019, 47(2):229-236.
Abstract:
This paper discusses the optimization of the meteorological station network information circulation path. Through analyzing the influence of two existing station information paths on the accuracy and consistency, the optimization scheme of the station network information circulation path is proposed. The scheme includes the optimization of the station network information management path based on a twolevel approval mechanism, the optimization of the station network information transmission path based on a realtime detectionfeedback mechanism, and the optimization of station network information version control. The optimization scheme is implemented in the provincial meteorological operation by a combined way of management tools and the business platform. The data analysis shows that this optimization scheme had obvious effect on the improvement of the quality of station network information and helped to achieve the standardized management of meteorological station network information.
This paper discusses the optimization of the meteorological station network information circulation path. Through analyzing the influence of two existing station information paths on the accuracy and consistency, the optimization scheme of the station network information circulation path is proposed. The scheme includes the optimization of the station network information management path based on a twolevel approval mechanism, the optimization of the station network information transmission path based on a realtime detectionfeedback mechanism, and the optimization of station network information version control. The optimization scheme is implemented in the provincial meteorological operation by a combined way of management tools and the business platform. The data analysis shows that this optimization scheme had obvious effect on the improvement of the quality of station network information and helped to achieve the standardized management of meteorological station network information.
2019, 47(2):237-243.
Abstract:
Aiming at the performance bottleneck of the CIMISS ServiceOriented Data Storage System in operation, based on the analysis of system processes, this paper carries out the corresponding optimization on the different aspects of performance bottlenecks, analyzes the differences between traditional Share Disk and latest Share Nothing structure, designs the deployment scheme of distributed databases and the technology solution of the embedded CIMISS for data storage performance issues. In order to optimize the performance bottleneck of the scheduling process, the corresponding scheduling records are optimized. The data analysis shows that the service performance and operational stability of SOD are improved significantly; the performance of some interfaces is improved by more than 10 times; and the time efficiency of unstructured data storage is higher than 98%, when the above optimization measures are implemented. It provides stable and reliable data support for all types of meteorological service applications.
Aiming at the performance bottleneck of the CIMISS ServiceOriented Data Storage System in operation, based on the analysis of system processes, this paper carries out the corresponding optimization on the different aspects of performance bottlenecks, analyzes the differences between traditional Share Disk and latest Share Nothing structure, designs the deployment scheme of distributed databases and the technology solution of the embedded CIMISS for data storage performance issues. In order to optimize the performance bottleneck of the scheduling process, the corresponding scheduling records are optimized. The data analysis shows that the service performance and operational stability of SOD are improved significantly; the performance of some interfaces is improved by more than 10 times; and the time efficiency of unstructured data storage is higher than 98%, when the above optimization measures are implemented. It provides stable and reliable data support for all types of meteorological service applications.
2019, 47(2):244-254.
Abstract:
Based on the data from the national meteorological stations in the northeastern QinghaiTibet Plateau, the occurrence frequencies of monthly, quarterly and annual strong cold air for each station and the entire region from 1961 and 2015 are calculated, and then we analyzes the characteristics of strong cold air and its influences with the climate diagnosis method. It is found: In terms of spatial scale, from 1961 to 2015, there were strong cold air averagely in 20 stations collected throughout a year, 11 stations in spring, 17 stations in summer, 12 stations in autumn and 8 stations in winter, showing a significant decline. In terms of time scale, from 1961 to 2015, the annual occurrence frequency of strong cold air influencing the northeast QinghaiTibet Plateau decreased by 0.401 per 10 years, showing an obvious decrease tendency. In addition, the occurrence frequencies of strong cold air in summer and autumn in this region decreased by 0.094 and 0.119 per 10 years, respectively, also presenting a significant decline. However, the annual strong cold air events in spring and winter were decreased by 0.087 and 0.076 time per 10 years, respectively, without significant decline. Moreover, the occurrence frequency of strong cold air in the northeastern QinghaiTibet Plateau showed a significant decline from 1983 to 2014 and insignificant decline from 1962 to 1982. With respect to its influence, the annual occurrence frequency of strong cold air in the northeastern QinghaiTibet Plateau reduced due to the significant increase of average minimum temperature and a significant decrease in the number of strong wind days from 1961 to 2015.
Based on the data from the national meteorological stations in the northeastern QinghaiTibet Plateau, the occurrence frequencies of monthly, quarterly and annual strong cold air for each station and the entire region from 1961 and 2015 are calculated, and then we analyzes the characteristics of strong cold air and its influences with the climate diagnosis method. It is found: In terms of spatial scale, from 1961 to 2015, there were strong cold air averagely in 20 stations collected throughout a year, 11 stations in spring, 17 stations in summer, 12 stations in autumn and 8 stations in winter, showing a significant decline. In terms of time scale, from 1961 to 2015, the annual occurrence frequency of strong cold air influencing the northeast QinghaiTibet Plateau decreased by 0.401 per 10 years, showing an obvious decrease tendency. In addition, the occurrence frequencies of strong cold air in summer and autumn in this region decreased by 0.094 and 0.119 per 10 years, respectively, also presenting a significant decline. However, the annual strong cold air events in spring and winter were decreased by 0.087 and 0.076 time per 10 years, respectively, without significant decline. Moreover, the occurrence frequency of strong cold air in the northeastern QinghaiTibet Plateau showed a significant decline from 1983 to 2014 and insignificant decline from 1962 to 1982. With respect to its influence, the annual occurrence frequency of strong cold air in the northeastern QinghaiTibet Plateau reduced due to the significant increase of average minimum temperature and a significant decrease in the number of strong wind days from 1961 to 2015.
2019, 47(2):255-261.
Abstract:
Using the MJO (MaddenJulian Oscillation) index data from 1979 to 2015 supplied by the Australian Bureau of Meteorology, the NCEP/NCAR global reanalysis data, and the typhoon data index from the Shanghai Typhoon Institute of the China Meteorological Administration, this paper analyzes the relationship between the different phases and intensities of MJO and the impact of tropical cyclones from July to October in Hainan. The results show that the tropical cyclone active and quiet periods affecting Hainan Island are related to the phases and intensities of MJO from July to October, but the corresponding MJO phases and intensities of tropical cyclone active and quiet periods are different in the period of July to August and the period of September to October. In July and August, when MJO is in strong phase (the third, sixth phase) or weak state (the fourth phase), it is beneficial for tropical cyclones to influence Hainan Province. When MJO is in first, second and eighth phases in strong state, it is not conducive to tropical cyclone’s influence in Hainan. In September and October, when MJO is in the seventh phase, it is favorable for tropical cyclones to affect Hainan Island. When MJO is in first and eighth phases, it is not conducive to tropical cyclones affecting Hainan Island. In July, August, September, and October, the circulation situations corresponding the MJO phase that is favorable/unfavorable to the activities of tropical cyclones, are basically the opposite.
Using the MJO (MaddenJulian Oscillation) index data from 1979 to 2015 supplied by the Australian Bureau of Meteorology, the NCEP/NCAR global reanalysis data, and the typhoon data index from the Shanghai Typhoon Institute of the China Meteorological Administration, this paper analyzes the relationship between the different phases and intensities of MJO and the impact of tropical cyclones from July to October in Hainan. The results show that the tropical cyclone active and quiet periods affecting Hainan Island are related to the phases and intensities of MJO from July to October, but the corresponding MJO phases and intensities of tropical cyclone active and quiet periods are different in the period of July to August and the period of September to October. In July and August, when MJO is in strong phase (the third, sixth phase) or weak state (the fourth phase), it is beneficial for tropical cyclones to influence Hainan Province. When MJO is in first, second and eighth phases in strong state, it is not conducive to tropical cyclone’s influence in Hainan. In September and October, when MJO is in the seventh phase, it is favorable for tropical cyclones to affect Hainan Island. When MJO is in first and eighth phases, it is not conducive to tropical cyclones affecting Hainan Island. In July, August, September, and October, the circulation situations corresponding the MJO phase that is favorable/unfavorable to the activities of tropical cyclones, are basically the opposite.
2019, 47(2):262-268.
Abstract:
An objective method is used to identify the Southern Branch Trough (SBT) activity by means of the NCEP/NCAR daily reanalysis dataset from 1981 to 2017. Based on the daily SBT activity and the precipitation data from 156 national observation stations in Sichuan, the temporal and spatial distribution characteristics of SBT and its impact on Sichuan precipitation are investigated. The results show that SBT appears 47.9 times per year and the monthly distribution is bimodal, with the highest frequencies occurring in January and May. The most frequent activitive area is around 90°E and 22° to 24°N, to the south of the QinghaiXizang Plateau and north of the Bay of Bengal. SBT usually enhances from November to January. The intensity of SBT generally decreases with increasing longitude, but there are enhanced areas near 86°E and 96°E. About 73.97% of SBT activities will produce precipitation processes in Sichuan, with the high frequency areas located in the southeast and south parts of the basin. When the South Branch is westward, Sichuan is more prone to precipitation. However, precipitation processes with weaker SBT intensity are generally heavier.
An objective method is used to identify the Southern Branch Trough (SBT) activity by means of the NCEP/NCAR daily reanalysis dataset from 1981 to 2017. Based on the daily SBT activity and the precipitation data from 156 national observation stations in Sichuan, the temporal and spatial distribution characteristics of SBT and its impact on Sichuan precipitation are investigated. The results show that SBT appears 47.9 times per year and the monthly distribution is bimodal, with the highest frequencies occurring in January and May. The most frequent activitive area is around 90°E and 22° to 24°N, to the south of the QinghaiXizang Plateau and north of the Bay of Bengal. SBT usually enhances from November to January. The intensity of SBT generally decreases with increasing longitude, but there are enhanced areas near 86°E and 96°E. About 73.97% of SBT activities will produce precipitation processes in Sichuan, with the high frequency areas located in the southeast and south parts of the basin. When the South Branch is westward, Sichuan is more prone to precipitation. However, precipitation processes with weaker SBT intensity are generally heavier.
2019, 47(2):269-275.
Abstract:
Based on the data of evaporation, temperature, precipitation, sunshine duration, vapor pressure from 4 meteorological stations in Huangnan of Qinghai Province in the recent 54 years, using the data from the geographic information system, by means of the methods of mathematical statistics, linear regression and MannKendall test, the trends of spatial and temporal variation of evaporation in Huangnan are studied, and the characteristics of evaporation variation and the influencing factors are analyzed. The results indicated: (1) The average annual evaporation in Huangnan was 1441.5 mm from 1961 to 2013, which showed an obvious decreasing trend. In the 1960s and 1970s, the evaporation capacity had an increasing tendency. From the 1980s, the evaporation capacity decreased, presenting a declining trend. (2) The evaporation was the greatest in spring and summer, accounting for over 60 percent of average annual capacity, and it was less in autumn and winter. Evaporation capacity saw a decreasing trend in all seasons, especially in spring, then in summer. (3) In 1973, Huangnan experienced a sudden change in annual evaporation from great to low, and seasonal sudden change from great to low happened in the spring of 1973, summer of 1975, autumn of 1976, and winter of 1974, respectively. (4) The analysis of the influencing factors of evaporation shows that evaporation had a significant positive correlation with sunshine and a negative correlation with vapor pressure. The reduction of sunshine duration was the main influencing factor of evaporation decrease.
Based on the data of evaporation, temperature, precipitation, sunshine duration, vapor pressure from 4 meteorological stations in Huangnan of Qinghai Province in the recent 54 years, using the data from the geographic information system, by means of the methods of mathematical statistics, linear regression and MannKendall test, the trends of spatial and temporal variation of evaporation in Huangnan are studied, and the characteristics of evaporation variation and the influencing factors are analyzed. The results indicated: (1) The average annual evaporation in Huangnan was 1441.5 mm from 1961 to 2013, which showed an obvious decreasing trend. In the 1960s and 1970s, the evaporation capacity had an increasing tendency. From the 1980s, the evaporation capacity decreased, presenting a declining trend. (2) The evaporation was the greatest in spring and summer, accounting for over 60 percent of average annual capacity, and it was less in autumn and winter. Evaporation capacity saw a decreasing trend in all seasons, especially in spring, then in summer. (3) In 1973, Huangnan experienced a sudden change in annual evaporation from great to low, and seasonal sudden change from great to low happened in the spring of 1973, summer of 1975, autumn of 1976, and winter of 1974, respectively. (4) The analysis of the influencing factors of evaporation shows that evaporation had a significant positive correlation with sunshine and a negative correlation with vapor pressure. The reduction of sunshine duration was the main influencing factor of evaporation decrease.
2019, 47(2):276-281.
Abstract:
Based on GABLS2 (the 2nd case of Global Energy and Water Cycle Experiment Atmospheric Boundary Layer Study), a SCM (Single Column Model) experiment is constructed to evaluate the diurnal cycle of PBL (Planetary Boundary Layer) processes in GRAPES（Global and Regional Assimilation and PrEdiction System）. Compared with observation and LES (Large Eddy Simulation), GRAPES simulates the 2m temperature reasonably with the prescribed surface temperature forcing. However, it is found that the simulated downward sensible heat flux，10m wind speed, surface friction velocity, and PBL height are overestimated under stable condition (during nighttime), while the simulated upward sensible heat flux and PBL height are underestimated under unstable condition (during daytime). Sensitivity experiment shows that the simulated 10m wind speed and friction velocity in the stable boundary layer, as well as the profiles of wind and temperature in the convective boundary layer, are closer to LES if the background diffusion values are reduced.
Based on GABLS2 (the 2nd case of Global Energy and Water Cycle Experiment Atmospheric Boundary Layer Study), a SCM (Single Column Model) experiment is constructed to evaluate the diurnal cycle of PBL (Planetary Boundary Layer) processes in GRAPES（Global and Regional Assimilation and PrEdiction System）. Compared with observation and LES (Large Eddy Simulation), GRAPES simulates the 2m temperature reasonably with the prescribed surface temperature forcing. However, it is found that the simulated downward sensible heat flux，10m wind speed, surface friction velocity, and PBL height are overestimated under stable condition (during nighttime), while the simulated upward sensible heat flux and PBL height are underestimated under unstable condition (during daytime). Sensitivity experiment shows that the simulated 10m wind speed and friction velocity in the stable boundary layer, as well as the profiles of wind and temperature in the convective boundary layer, are closer to LES if the background diffusion values are reduced.
2019, 47(2):282-288.
Abstract:
Based on the wind data at four weather stations in Zhoushan and ERAinterim data during 2008-2016, the climatic characteristics of gust factors with the distribution of mean wind speed, wind direction, hour and month are analyzed respectively. The correlation analysis is carried out between gust factors and atmospheric stability, the ratio of the wind speed at the levels of 250 to 1000 m to the wind speed of 10 m, and the 6h temperature variation at different levels in the atmospheric boundary layer. Then the best predictors are selected and the cyclic tests of gust forecast are conducted based on the BP artificial neural network method. The results show that (1) When the mean wind speed is small, the gust factors fluctuate greatly. The gust factors of air flows near the mainland or from the land direction are larger. (2) The gust factors are relatively larger in 11:00-16:00, when the turbulence affected by solar radiation is relatively strong. The gust factors from July to September and November to December are also relatively larger owing to typhoon influences or the larger surface roughness respectively. (3) The relations of the gust factors with the ratio of the wind speed of 250-1000 m to the wind speed of 10 m and temperature present positive correlation, and there presents negative correlation with stability parameters at the atmospheric boundary layer. It proves that the main physical cause of the gust is relevant to the vertical turbulent transport of momentums. (4) The cyclic tests reveal the important role of stability and turbulence at the atmospheric boundary layer in gust forecast. The gust absolute errors and their variances of the optimum groups are reduced by 10% to 25%, compared with those of comparison groups at four stations.
Based on the wind data at four weather stations in Zhoushan and ERAinterim data during 2008-2016, the climatic characteristics of gust factors with the distribution of mean wind speed, wind direction, hour and month are analyzed respectively. The correlation analysis is carried out between gust factors and atmospheric stability, the ratio of the wind speed at the levels of 250 to 1000 m to the wind speed of 10 m, and the 6h temperature variation at different levels in the atmospheric boundary layer. Then the best predictors are selected and the cyclic tests of gust forecast are conducted based on the BP artificial neural network method. The results show that (1) When the mean wind speed is small, the gust factors fluctuate greatly. The gust factors of air flows near the mainland or from the land direction are larger. (2) The gust factors are relatively larger in 11:00-16:00, when the turbulence affected by solar radiation is relatively strong. The gust factors from July to September and November to December are also relatively larger owing to typhoon influences or the larger surface roughness respectively. (3) The relations of the gust factors with the ratio of the wind speed of 250-1000 m to the wind speed of 10 m and temperature present positive correlation, and there presents negative correlation with stability parameters at the atmospheric boundary layer. It proves that the main physical cause of the gust is relevant to the vertical turbulent transport of momentums. (4) The cyclic tests reveal the important role of stability and turbulence at the atmospheric boundary layer in gust forecast. The gust absolute errors and their variances of the optimum groups are reduced by 10% to 25%, compared with those of comparison groups at four stations.
2019, 47(2):289-298.
Abstract:
Based on the daily average temperature and surface (0 cm) temperature data observed by 71 meteorological stations in Zhejiang Province in 2016, the applicability of ERA reanalysis data of land surface temperature is evaluated. By calculating the correlation coefficients, mean deviation, mean absolute deviation, root mean square error and Nash efficiency coefficient between the two sets of reanalysis data (ERA5 and ERAInterim) and the observation data, the ERA reanalysis data is comprehensively evaluated. Both the spatial and temporal distribution characteristics and changes of 2m temperature in Zhejiang Province can be better reproduced. The correlation coefficient is higher than 0.98, and the absolute deviation is smaller. For surface temperature, the applicability of the two sets of reanalysis data is worse than that of air temperature, mainly because in the two sets of reanalysis data, the surface temperatures are lower than the observed values, and the deviation in summer is significantly greater than in other seasons, but the correlation coefficients of most sites are higher than 0.9, while the root mean square error is higher than 2 ℃. In general, the two sets of reanalysis data of land surface temperature have good applicability in Zhejiang Province. ERA5 is better than ERAInterim as a whole and the improvement of surface temperature is more obvious.
Based on the daily average temperature and surface (0 cm) temperature data observed by 71 meteorological stations in Zhejiang Province in 2016, the applicability of ERA reanalysis data of land surface temperature is evaluated. By calculating the correlation coefficients, mean deviation, mean absolute deviation, root mean square error and Nash efficiency coefficient between the two sets of reanalysis data (ERA5 and ERAInterim) and the observation data, the ERA reanalysis data is comprehensively evaluated. Both the spatial and temporal distribution characteristics and changes of 2m temperature in Zhejiang Province can be better reproduced. The correlation coefficient is higher than 0.98, and the absolute deviation is smaller. For surface temperature, the applicability of the two sets of reanalysis data is worse than that of air temperature, mainly because in the two sets of reanalysis data, the surface temperatures are lower than the observed values, and the deviation in summer is significantly greater than in other seasons, but the correlation coefficients of most sites are higher than 0.9, while the root mean square error is higher than 2 ℃. In general, the two sets of reanalysis data of land surface temperature have good applicability in Zhejiang Province. ERA5 is better than ERAInterim as a whole and the improvement of surface temperature is more obvious.
2019, 47(2):299-311.
Abstract:
An exceptional shorttime strong rainfall happened in the Beichen district of Tianjin at the midnight of 8 Aug 2017 and its intensity surpassed 70 mm·h-1. Using the methods of multidata superposition analysis, quantitative analysis of radar echo parameters, and lowlevel wind field retrieval, etc., RMAPS (Rapidrefresh Multiscale Analysis and Prediction System) products and various observation data are used to analyze this rainfall. The results indicate: (1) The multicell storms in the southern extremity of MβCS (Mesoβscale Convective System) during the backpropagation caused this rainfall. The merging process had an important impact on the structure and enhancement of the storm system. After merging, echo volume parameter 〖WTBX〗V〖WTBZ〗40 〖KG*3〗(the volume of the reflectivity above 40 dBz) increased by 23.3%. Before the rise of 〖WTBX〗V〖WTBZ〗40, variable parameter 〖WTBX〗F〖WTBZ〗V40-up6 (the change of strong echo volume of above 40 dBz above 6 km height in 6 min) suddenly dropped, indicating that the echo was about to develop explosively. (2) The ground convergence line formed by the cold pool outflow and surface southeast winds was the key to maintain the convective system; the low level wind shear also influenced the trigger and development of convection; accompanied by heavy rainfall, CAPE suddenly dropped from the peak and the low level vertical wind shear index α increased, indicating the relationship among unstable energy, vertical wind shear, and convection process. (3) The large value area of the instability parameter SWEAT had an early indication of the heavy rainfall area; the lead time was about 3 hours; and the location where the surface warmwet area from the Bohai Sea and pseudo equivalent temperature dense zone met was the focus of falling area nowcast.
An exceptional shorttime strong rainfall happened in the Beichen district of Tianjin at the midnight of 8 Aug 2017 and its intensity surpassed 70 mm·h-1. Using the methods of multidata superposition analysis, quantitative analysis of radar echo parameters, and lowlevel wind field retrieval, etc., RMAPS (Rapidrefresh Multiscale Analysis and Prediction System) products and various observation data are used to analyze this rainfall. The results indicate: (1) The multicell storms in the southern extremity of MβCS (Mesoβscale Convective System) during the backpropagation caused this rainfall. The merging process had an important impact on the structure and enhancement of the storm system. After merging, echo volume parameter 〖WTBX〗V〖WTBZ〗40 〖KG*3〗(the volume of the reflectivity above 40 dBz) increased by 23.3%. Before the rise of 〖WTBX〗V〖WTBZ〗40, variable parameter 〖WTBX〗F〖WTBZ〗V40-up6 (the change of strong echo volume of above 40 dBz above 6 km height in 6 min) suddenly dropped, indicating that the echo was about to develop explosively. (2) The ground convergence line formed by the cold pool outflow and surface southeast winds was the key to maintain the convective system; the low level wind shear also influenced the trigger and development of convection; accompanied by heavy rainfall, CAPE suddenly dropped from the peak and the low level vertical wind shear index α increased, indicating the relationship among unstable energy, vertical wind shear, and convection process. (3) The large value area of the instability parameter SWEAT had an early indication of the heavy rainfall area; the lead time was about 3 hours; and the location where the surface warmwet area from the Bohai Sea and pseudo equivalent temperature dense zone met was the focus of falling area nowcast.
2019, 47(2):312-321.
Abstract:
An extreme cold wave event is analyzed on the isentropic potential vorticity (IPV) with the FNL reanalysis data from 1 Jan to 31 Jan 2016. The result shows that high potential vorticity (PV) was resulted from the splitting polar vortex, and the blocking of the front low PV and the proceeding northward moving of the rear low PV strengthened the meridional exchange of the PV. The high PV air continuously moved from the polar to the south, making the main body of the high PV continue to strengthen, and meanwhile, the high vortex also transported downward from the troposphere. The cold wave, which included three strands of cold air, developed from the upper to the bottom, settling in the north side of the upperlevel jet. In the southern tip a sinking airflow was most exuberant, which resulted from its interaction with the upperlevel jet. The sinking of the strong cold air made the cold wave influence the South China. As the high PV transmitted towards the south area, the low vortex system developed rapidly in the highlevel troposphere. When it moved to the eastern China, The East Asian Trough deepened rapidly, and finally induced the outbreak of strong cold air behind the trough. On the other hand, in the process of high PV transportation, the rear strongly sinking movement occurred to render the rapid development of the cold high on the ground and lead to the outbreak of cold wave weather.
An extreme cold wave event is analyzed on the isentropic potential vorticity (IPV) with the FNL reanalysis data from 1 Jan to 31 Jan 2016. The result shows that high potential vorticity (PV) was resulted from the splitting polar vortex, and the blocking of the front low PV and the proceeding northward moving of the rear low PV strengthened the meridional exchange of the PV. The high PV air continuously moved from the polar to the south, making the main body of the high PV continue to strengthen, and meanwhile, the high vortex also transported downward from the troposphere. The cold wave, which included three strands of cold air, developed from the upper to the bottom, settling in the north side of the upperlevel jet. In the southern tip a sinking airflow was most exuberant, which resulted from its interaction with the upperlevel jet. The sinking of the strong cold air made the cold wave influence the South China. As the high PV transmitted towards the south area, the low vortex system developed rapidly in the highlevel troposphere. When it moved to the eastern China, The East Asian Trough deepened rapidly, and finally induced the outbreak of strong cold air behind the trough. On the other hand, in the process of high PV transportation, the rear strongly sinking movement occurred to render the rapid development of the cold high on the ground and lead to the outbreak of cold wave weather.
Li Xiali
,
Pan Xianjie
,
Tong Yingxiang
,
Ni Ting
,
Huang Guogui
,
Li Jingan
,
Tao Jie
,
YaoYi
,
Ling Xinfeng
2019, 47(2):322-328.
Abstract:
Using the data from the Parsivel laser precipitation particle spectrometer combined with rainfall data and radar data, we analyze the structure characteristics and difference of raindrop spectrums of two heavy rains in Shouxian. In addition, the relationship between rain intensity and radar reflectivity factor is fitted. Results show that the rainfall intensity directly affects the characteristic parameters of the raindrop spectrum, and increases with the rainfall intensity. In the Meiyu front rainstorm, contributions to the total number concentration of raindrops with a diameter of 0.25 to 1.0 mm are the maximum, and rainfall intensity is the greatest. In the typhoon rainstorm, the contributions to the total number concentration of raindrops with a diameter of 0.75 to 1.0 mm are the greatest, but those to the total rainfall intensity of raindrops with a diameter of 1.0 to 1.25 mm are the greatest, which indicates that the larger particles contribute more greatly to the heavy rainfall; The ZR relationship of the Meiyu front rainstorm is 〖WTBX〗Z〖WTBZ〗=160〖WTBX〗I〖WTBZ〗1.47, and the 〖WTBX〗ZR〖WTBZ〗 relationship of the typhoon rain is 〖WTBX〗Z〖WTBZ〗=152〖WTBX〗I〖WTBZ〗1.30.
Using the data from the Parsivel laser precipitation particle spectrometer combined with rainfall data and radar data, we analyze the structure characteristics and difference of raindrop spectrums of two heavy rains in Shouxian. In addition, the relationship between rain intensity and radar reflectivity factor is fitted. Results show that the rainfall intensity directly affects the characteristic parameters of the raindrop spectrum, and increases with the rainfall intensity. In the Meiyu front rainstorm, contributions to the total number concentration of raindrops with a diameter of 0.25 to 1.0 mm are the maximum, and rainfall intensity is the greatest. In the typhoon rainstorm, the contributions to the total number concentration of raindrops with a diameter of 0.75 to 1.0 mm are the greatest, but those to the total rainfall intensity of raindrops with a diameter of 1.0 to 1.25 mm are the greatest, which indicates that the larger particles contribute more greatly to the heavy rainfall; The ZR relationship of the Meiyu front rainstorm is 〖WTBX〗Z〖WTBZ〗=160〖WTBX〗I〖WTBZ〗1.47, and the 〖WTBX〗ZR〖WTBZ〗 relationship of the typhoon rain is 〖WTBX〗Z〖WTBZ〗=152〖WTBX〗I〖WTBZ〗1.30.
2019, 47(2):329-336.
Abstract:
Based on the 6hour data of weather phenomena, visibility and common meteorological elements from 1981 to 2013 from 125 observation stations over Yunnan, considering the terrain heights, by means of the high resolution meteorological element interpolation method and the objective identification model of meteorological elements for foggy weather unsuitable for flights (the heavy fog with visibility less than 800 m), the influence of visual obstruction weather on airworthiness conditions and its climatic characteristics in Yunnan are analyzed. The results indicate that the primary visual obstruction weather in Yunnan was fog and mist, but the visual obstruction weather affecting airworthiness conditions was fog. Foggy weather unsuitable for flights has a close relationship with relative humidity (RH), wind speed (WS), and the difference of surface temperature and air temperature (〖WTBX〗T〖WTBZ〗s-〖WTBX〗T〖WTBZ〗a); moreover, the key point of occurrence and maintenance of foggy weather unsuitable for flights is the stable meteorological conditions of high humidity and weak wind, with the quantitative indicators: RH>98%, WS<3 m/s, (〖WTBX〗T〖WTBZ〗s-〖WTBX〗T〖WTBZ〗a)<3 ℃. The southern, southwestern and eastern Yunnan Province are the regions where foggy weather unsuitable for flights frequently occurres, especially JingdongSimaoXishuangbanna, XimengLancang, BaoshanTengchong, Luoping, etc. To compared with the data of observation stations, the spatial distribution of foggy weather unsuitable for flights judged by the high resolution data by the objective method has better correspondence with terrain, which can reasonably reflect the spatial distribution characteristics of complex terrain, while the middle, western and northeastern Yunnan are on the contrary.
Based on the 6hour data of weather phenomena, visibility and common meteorological elements from 1981 to 2013 from 125 observation stations over Yunnan, considering the terrain heights, by means of the high resolution meteorological element interpolation method and the objective identification model of meteorological elements for foggy weather unsuitable for flights (the heavy fog with visibility less than 800 m), the influence of visual obstruction weather on airworthiness conditions and its climatic characteristics in Yunnan are analyzed. The results indicate that the primary visual obstruction weather in Yunnan was fog and mist, but the visual obstruction weather affecting airworthiness conditions was fog. Foggy weather unsuitable for flights has a close relationship with relative humidity (RH), wind speed (WS), and the difference of surface temperature and air temperature (〖WTBX〗T〖WTBZ〗s-〖WTBX〗T〖WTBZ〗a); moreover, the key point of occurrence and maintenance of foggy weather unsuitable for flights is the stable meteorological conditions of high humidity and weak wind, with the quantitative indicators: RH>98%, WS<3 m/s, (〖WTBX〗T〖WTBZ〗s-〖WTBX〗T〖WTBZ〗a)<3 ℃. The southern, southwestern and eastern Yunnan Province are the regions where foggy weather unsuitable for flights frequently occurres, especially JingdongSimaoXishuangbanna, XimengLancang, BaoshanTengchong, Luoping, etc. To compared with the data of observation stations, the spatial distribution of foggy weather unsuitable for flights judged by the high resolution data by the objective method has better correspondence with terrain, which can reasonably reflect the spatial distribution characteristics of complex terrain, while the middle, western and northeastern Yunnan are on the contrary.
2019, 47(2):337-348.
Abstract:
In order to understand the distribution characteristics of lightning parameters for mountain and plain areas and their difference, and to bring up reference opinions on lightning protection engineering design and lightning risk assessment, the study utilizes the lightning monitoring data from December 2006 to December 2016, by mathematical statistics method, to make a contrastive analysis about the distribution characteristics of the frequency, polarity, peak current, and wave front steepness. The results show that the density of cloudtoground (CG) lightning in the mountain area was higher than that in the plain area; the percentage of positive CG lightning in the plain area was higher than that in the mountain area; and the percentage of positive flashes in the past 10 years had an increasing trend. The average intensity of positive CG lightning in the mountain area was 1.16 kA greater than that in the plain area, and the average intensity of negative CG lightning in the mountain area is 3.67 kA smaller than that in plain area, and intensity of total CG lightning in the plain area is 3.46 kA greater than that in the mountain area. The probability of lightning peak current (≥30 kA in the mountain area, 8.9% greater than that in the plain area). As the lightning peak current was greater than 100 kA, the probability in the plain area was 0.6% greater than that in the mountain area. The average steepness of positive CG lightning in the mountain area was 2.44 kA/μs and 2.31 kA/μs greater than that of negative and total CG lightning respectively, and the average steepness of positive, negative, and total CG lightning in the plain area was 3.41 kA/μs, 5.77 kA/μs, and 5.64 kA/μs greater than those in the mountain area, respectively. It shows that the probability of shielding failure in the mountain area is higher than that in the plain area, and the damage of positive CG lightning induction was greater than that of negative and total CG lightning; the occurrence of back flashover in plain is higher than that in the mountain area, and the damage of lightning induction was greater than that in the mountain area.
In order to understand the distribution characteristics of lightning parameters for mountain and plain areas and their difference, and to bring up reference opinions on lightning protection engineering design and lightning risk assessment, the study utilizes the lightning monitoring data from December 2006 to December 2016, by mathematical statistics method, to make a contrastive analysis about the distribution characteristics of the frequency, polarity, peak current, and wave front steepness. The results show that the density of cloudtoground (CG) lightning in the mountain area was higher than that in the plain area; the percentage of positive CG lightning in the plain area was higher than that in the mountain area; and the percentage of positive flashes in the past 10 years had an increasing trend. The average intensity of positive CG lightning in the mountain area was 1.16 kA greater than that in the plain area, and the average intensity of negative CG lightning in the mountain area is 3.67 kA smaller than that in plain area, and intensity of total CG lightning in the plain area is 3.46 kA greater than that in the mountain area. The probability of lightning peak current (≥30 kA in the mountain area, 8.9% greater than that in the plain area). As the lightning peak current was greater than 100 kA, the probability in the plain area was 0.6% greater than that in the mountain area. The average steepness of positive CG lightning in the mountain area was 2.44 kA/μs and 2.31 kA/μs greater than that of negative and total CG lightning respectively, and the average steepness of positive, negative, and total CG lightning in the plain area was 3.41 kA/μs, 5.77 kA/μs, and 5.64 kA/μs greater than those in the mountain area, respectively. It shows that the probability of shielding failure in the mountain area is higher than that in the plain area, and the damage of positive CG lightning induction was greater than that of negative and total CG lightning; the occurrence of back flashover in plain is higher than that in the mountain area, and the damage of lightning induction was greater than that in the mountain area.
2019, 47(2):349-354.
Abstract:
Comprehensive and accurate analysis of soil resistivity is significant to the optimum design of grounding devices. This paper builds soil resistivity measurement models by the CDEGS (Current Distribution, Electromagnetic fields, Grounding and Soil structure analysis) system based on the Wenner fourelectrode method, simulates the soil resistivity of the selfdefined soil structure, and makes inversion analysis to obtain the simulated soil structure parameters. Then by making a comparative analysis between the simulated and defined soil structure parameters, the validity of soil structure inversion analysis is verified. This paper conducts field tests and a comparison of tested grounding resistance and simulated grounding resistance to validate the validity of soil structure and grounding resistance inversion analysis. In addition, the effect of vertical and horizontal grounding devices on grounding resistance reducing is discussed simply in the situation of twolayer soil structure. The results indicate that the system can obtain the real and comprehensive soil structure and grounding resistance，which has a great importance to the design of grounding device and the assessment of grounding resistance.
Comprehensive and accurate analysis of soil resistivity is significant to the optimum design of grounding devices. This paper builds soil resistivity measurement models by the CDEGS (Current Distribution, Electromagnetic fields, Grounding and Soil structure analysis) system based on the Wenner fourelectrode method, simulates the soil resistivity of the selfdefined soil structure, and makes inversion analysis to obtain the simulated soil structure parameters. Then by making a comparative analysis between the simulated and defined soil structure parameters, the validity of soil structure inversion analysis is verified. This paper conducts field tests and a comparison of tested grounding resistance and simulated grounding resistance to validate the validity of soil structure and grounding resistance inversion analysis. In addition, the effect of vertical and horizontal grounding devices on grounding resistance reducing is discussed simply in the situation of twolayer soil structure. The results indicate that the system can obtain the real and comprehensive soil structure and grounding resistance，which has a great importance to the design of grounding device and the assessment of grounding resistance.
2019, 47(2):355-360.
Abstract:
According to the safe firing range management requirements of weather modification operation, an analysis is made of the factors influencing the safe firing range of weather modification operation，including equipment performance, ammunition stability, high altitude airflow, site elevation and personnel operation level, etc. This paper puts forward a method for drawing the safe firing range map of weather modification operation, and the specific steps are as follows: (1) the information interpolation processing of the ejection data tables; (2) the artificial identification of the sensitive area of the ground safe operation; (3) the inverse calculation of projectile impact points corresponding to initial firing data; (4) the error correction design of different influence factors; (5) the fusion processing of geographic information data; (6) the output of the safety shooting range map. This paper also designs the system for drawing safety shooting range maps based on the artificial identification technology of highresolution satellite image data and digital elevation model data (DEM data). Practical application shows that the safe firing range map outputted by the system can solve the problems of incomplete safetymarking elements, low resolution, and low level in information in the traditional maps, has practical value for improving the operational efficiency and safety management level, and can be popularized to all levels of weather modification operations.
According to the safe firing range management requirements of weather modification operation, an analysis is made of the factors influencing the safe firing range of weather modification operation，including equipment performance, ammunition stability, high altitude airflow, site elevation and personnel operation level, etc. This paper puts forward a method for drawing the safe firing range map of weather modification operation, and the specific steps are as follows: (1) the information interpolation processing of the ejection data tables; (2) the artificial identification of the sensitive area of the ground safe operation; (3) the inverse calculation of projectile impact points corresponding to initial firing data; (4) the error correction design of different influence factors; (5) the fusion processing of geographic information data; (6) the output of the safety shooting range map. This paper also designs the system for drawing safety shooting range maps based on the artificial identification technology of highresolution satellite image data and digital elevation model data (DEM data). Practical application shows that the safe firing range map outputted by the system can solve the problems of incomplete safetymarking elements, low resolution, and low level in information in the traditional maps, has practical value for improving the operational efficiency and safety management level, and can be popularized to all levels of weather modification operations.
2019, 47(2):361-366.
Abstract:
This article is to introduce the public version of Smart Meteorology based on Wechat applet technology. It realizes the visualization of meteorological data by means of graphic drawing technology based on the Wechat applet technology. We develop several functional pages that meet the public needs by integrating meteorological data with news, videos, pictures, etc. The public version of Smart Meteorology has been widely used in meteorological services in Zhejiang Province, and it provides a reference for the application of Wechat applets in public meteorological service.
This article is to introduce the public version of Smart Meteorology based on Wechat applet technology. It realizes the visualization of meteorological data by means of graphic drawing technology based on the Wechat applet technology. We develop several functional pages that meet the public needs by integrating meteorological data with news, videos, pictures, etc. The public version of Smart Meteorology has been widely used in meteorological services in Zhejiang Province, and it provides a reference for the application of Wechat applets in public meteorological service.
2019, 47(2):367-372.
Abstract:
The thesis introduces the frame, data base, function module design and operation application of the Agricultural Meteorology Observation Report Working Base Statistical System (AgMOBase).The system is a matched operation system for the Agricultural Meteorology Observation Report Operation System (AgMODOS), which is developed by adopting the objectoriental technique and modular construction technique, consisting of fourlevel frameworks: data, technology, application and user. The system is already being implemented in the operation of agricultural meteorology observation stations across China, to conduct the daily basicdata statistical service as prescribed by the quality assessments of agrometeorological observation and software application by the relevant meteorological departments and provide the detailed monthly/annual base statistical reports.
The thesis introduces the frame, data base, function module design and operation application of the Agricultural Meteorology Observation Report Working Base Statistical System (AgMOBase).The system is a matched operation system for the Agricultural Meteorology Observation Report Operation System (AgMODOS), which is developed by adopting the objectoriental technique and modular construction technique, consisting of fourlevel frameworks: data, technology, application and user. The system is already being implemented in the operation of agricultural meteorology observation stations across China, to conduct the daily basicdata statistical service as prescribed by the quality assessments of agrometeorological observation and software application by the relevant meteorological departments and provide the detailed monthly/annual base statistical reports.
External LinksChina Meteorological AdministrationCMA Meteorological Observation CentreChinese Academy of Meteorological SciencesBeijing Meteorological ServiceNational Satellite Meteorological Center
You are thevisitors
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.