Volume 49,Issue 6,2021 Table of Contents
2021, 49(6):823-829.
Abstract:
Sea fog, whether on the sea or the coast, has adverse effects on transportation, marine fishing, marine development projects, and military activities due to its poor visibility. Therefore, realtime monitoring and forecasting of sea fog are essential. This paper proposes a multichannel image fusion segmentation algorithm for stationary meteorological satellites based on deep learning. The DLinkNet deep neural network semantic segmentation algorithm model is used to study the 16channel Himawari8 satellite data with a spatial resolution of 0.5 km in the Yellow Sea and the Bohai Sea. Using mIOU (mean Intersection Over Union) and observation value test as evaluation indicators, the mIOU on the test set is 0.9436, and comparing the results of satellite test data with the results of marine observation data. It was concluded that the accuracy rate of fog area (detect fog and real fog / detect fog) is 66.5%, the recognition rate of fog area (detect fog and real fog / (real fog-cloud coverage)) is 51.9%, and the detection accuracy rate (detection correct samples / total samples) is 93.2%. In conclusion, the method proposed in this paper can provide a reliable reference for sea fog monitoring.
Sea fog, whether on the sea or the coast, has adverse effects on transportation, marine fishing, marine development projects, and military activities due to its poor visibility. Therefore, realtime monitoring and forecasting of sea fog are essential. This paper proposes a multichannel image fusion segmentation algorithm for stationary meteorological satellites based on deep learning. The DLinkNet deep neural network semantic segmentation algorithm model is used to study the 16channel Himawari8 satellite data with a spatial resolution of 0.5 km in the Yellow Sea and the Bohai Sea. Using mIOU (mean Intersection Over Union) and observation value test as evaluation indicators, the mIOU on the test set is 0.9436, and comparing the results of satellite test data with the results of marine observation data. It was concluded that the accuracy rate of fog area (detect fog and real fog / detect fog) is 66.5%, the recognition rate of fog area (detect fog and real fog / (real fog-cloud coverage)) is 51.9%, and the detection accuracy rate (detection correct samples / total samples) is 93.2%. In conclusion, the method proposed in this paper can provide a reliable reference for sea fog monitoring.
2021, 49(6):830-837.
Abstract:
Based on hourly observations from more than 2400 national weather stations in 2010-2015, this paper evaluates and compares the surface soil temperatures of EAR70, CLDAS and ERAInterim. 〖JP2〗The main conclusions are: CLDAS surface soil temperature had the highest accuracy in space (ME was -0.5 ℃, 〖JP〗RMSE was 3.0 ℃, R was 0.96). EAR70 benefited from the initial land surface field with CLDAS’s highprecision ME improved. The accuracy of reanalysis surface soil temperature was significantly reduced at around 06:00 and in summer and autumn. Reanalysis surface soil temperature exhibited a cold deviation during the relatively highvalue period. The reason was that the simulated soil temperature value rose slowly, and the corresponding parameterization scheme needed to be modified. There was a cold deviation in the Northeast region where snow covered the ground in winter, which may be related to the snow cover. The land surface parameterization scheme needed to be improved. In the complex terrain of the QinghaiTibet Plateau, CLDAS, which integrated ground observations, performed a good precision in atmospheric forcing data and thus improved soil simulation. The resolution of ERAInterim was relatively coarse and not suitable for the QinghaiTibet Plateau or coastal areas. Benefitted from CLDAS’s soil states in good quality, the accuracy of EAR70 had been improved in the QinghaiTibet Plateau. The high accuracy of the soil state’s initial field decreased significantly following the time increased after observation entering the assimilation system. Therefore, the realtime assimilation method used in CLDAS can improve the accuracy of soil temperature signals effectively.
Based on hourly observations from more than 2400 national weather stations in 2010-2015, this paper evaluates and compares the surface soil temperatures of EAR70, CLDAS and ERAInterim. 〖JP2〗The main conclusions are: CLDAS surface soil temperature had the highest accuracy in space (ME was -0.5 ℃, 〖JP〗RMSE was 3.0 ℃, R was 0.96). EAR70 benefited from the initial land surface field with CLDAS’s highprecision ME improved. The accuracy of reanalysis surface soil temperature was significantly reduced at around 06:00 and in summer and autumn. Reanalysis surface soil temperature exhibited a cold deviation during the relatively highvalue period. The reason was that the simulated soil temperature value rose slowly, and the corresponding parameterization scheme needed to be modified. There was a cold deviation in the Northeast region where snow covered the ground in winter, which may be related to the snow cover. The land surface parameterization scheme needed to be improved. In the complex terrain of the QinghaiTibet Plateau, CLDAS, which integrated ground observations, performed a good precision in atmospheric forcing data and thus improved soil simulation. The resolution of ERAInterim was relatively coarse and not suitable for the QinghaiTibet Plateau or coastal areas. Benefitted from CLDAS’s soil states in good quality, the accuracy of EAR70 had been improved in the QinghaiTibet Plateau. The high accuracy of the soil state’s initial field decreased significantly following the time increased after observation entering the assimilation system. Therefore, the realtime assimilation method used in CLDAS can improve the accuracy of soil temperature signals effectively.
2021, 49(6):838-843.
Abstract:
The limitation of the meteorological temperature verification system is that the degree of automation cannot meet the need of increasing workload. Aiming to realise temperature verification without personnel deployment, this paper proposes a meteorological temperature verification system based on the robot arm. To implement the workflow of the parallel control strategy, the system framework integrates device, networking, communication, and data storage levels. The vital issue of system building is shielding the interference from power grounding, electromagnetic field changing, and device communication. An optimisation method is proposed for interference shielding, and multiple tests are carried out for comparison. The results show that the indicating value of the precision thermometer can be restored to a steady state of dynamic balance, which improves the intelligence of the system and the precision of metrological verification.
The limitation of the meteorological temperature verification system is that the degree of automation cannot meet the need of increasing workload. Aiming to realise temperature verification without personnel deployment, this paper proposes a meteorological temperature verification system based on the robot arm. To implement the workflow of the parallel control strategy, the system framework integrates device, networking, communication, and data storage levels. The vital issue of system building is shielding the interference from power grounding, electromagnetic field changing, and device communication. An optimisation method is proposed for interference shielding, and multiple tests are carried out for comparison. The results show that the indicating value of the precision thermometer can be restored to a steady state of dynamic balance, which improves the intelligence of the system and the precision of metrological verification.
2021, 49(6):844-850.
Abstract:
Weather radar echoes need to be fused with geographic information to locate radar echoes and guide meteorological services. The Radar Operational Software Engineering (ROSE) has designed a new open map format and adopted one document with national map data to dynamically match radar stations. This method improves the inconvenience that the Principal User Processor (PUP) system needs each site to apply for customized maps in the existing radar service system. The ROSE product display subsystem supports the map adaptive display of various weather radars and their data under different earth projection modes. The design pattern is introduced into the program design of the map application submodule, which effectively solves the problem of display efficiency of refined map data and realizes the balance between display information and efficiency.
Weather radar echoes need to be fused with geographic information to locate radar echoes and guide meteorological services. The Radar Operational Software Engineering (ROSE) has designed a new open map format and adopted one document with national map data to dynamically match radar stations. This method improves the inconvenience that the Principal User Processor (PUP) system needs each site to apply for customized maps in the existing radar service system. The ROSE product display subsystem supports the map adaptive display of various weather radars and their data under different earth projection modes. The design pattern is introduced into the program design of the map application submodule, which effectively solves the problem of display efficiency of refined map data and realizes the balance between display information and efficiency.
2021, 49(6):851-859.
Abstract:
As a satellite ground application system becomes larger and larger and the network environment becomes more and more complex, each subsystem transmits data information within the same Open Shortest Path First (OSPF) network area. As a result, the LinkState Database (LSDB) maintained by each router becomes bloated. The calculation of a large LSDB leads a more consumption within the device, which increases its burden. In addition, the change of network topology will cause the recalculation of all routers in the whole domain. This paper applies the OSPF dynamic routing protocol area division feature to the satellite ground application system to carry out hierarchical segmentation of the overall network structure, dividing the backbone area and nonbackbone area. First, it controls the routing paths of routers in an area to access other areas, limiting LSA flooding within the area, reducing the number of maintained LSDBS and the number of routing entries in the routing table, saving resources at the control layer and allocating practical resource to data forwarding at the data layer. Thus, the data forwarding rate of the whole satellite ground application network system can be improved. Second, the regional division of the entire network can effectively control the influence of topology change within the region, and the change of any regional network topology will not affect the change of the whole network system, improving the stability and expansibility of the entire network system structure of satellite ground application.
As a satellite ground application system becomes larger and larger and the network environment becomes more and more complex, each subsystem transmits data information within the same Open Shortest Path First (OSPF) network area. As a result, the LinkState Database (LSDB) maintained by each router becomes bloated. The calculation of a large LSDB leads a more consumption within the device, which increases its burden. In addition, the change of network topology will cause the recalculation of all routers in the whole domain. This paper applies the OSPF dynamic routing protocol area division feature to the satellite ground application system to carry out hierarchical segmentation of the overall network structure, dividing the backbone area and nonbackbone area. First, it controls the routing paths of routers in an area to access other areas, limiting LSA flooding within the area, reducing the number of maintained LSDBS and the number of routing entries in the routing table, saving resources at the control layer and allocating practical resource to data forwarding at the data layer. Thus, the data forwarding rate of the whole satellite ground application network system can be improved. Second, the regional division of the entire network can effectively control the influence of topology change within the region, and the change of any regional network topology will not affect the change of the whole network system, improving the stability and expansibility of the entire network system structure of satellite ground application.
2021, 49(6):860-868.
Abstract:
In order to solve the urgent business needs of CMACast defects and provincial users to obtain provincial realtime observation data and gridded realtime datasets, the provincial data sharing system based on the message notification mechanism is designed and implemented. The system integrates business and data resources based on the rabbitMQ message mechanism. It adopts multilayer architecture, which can meet national and provincial data sharing needs such as fast and orderly data download based on CMANet and supplementary adjustment of CMACast. It supports highspeed transmission of largecapacity data, HTTP, FTP, SFTP and other data transmission protocols. The provincial coordination system has been operational, providing provincial meteorological departments 25 kinds of meteorological data with intelligent grid products and multisource realtime datasets. The average amount of data shared per month is 6.3 T, and the establishment of fullprocess monitoring to ensure the timeliness of data sharing effectively.
In order to solve the urgent business needs of CMACast defects and provincial users to obtain provincial realtime observation data and gridded realtime datasets, the provincial data sharing system based on the message notification mechanism is designed and implemented. The system integrates business and data resources based on the rabbitMQ message mechanism. It adopts multilayer architecture, which can meet national and provincial data sharing needs such as fast and orderly data download based on CMANet and supplementary adjustment of CMACast. It supports highspeed transmission of largecapacity data, HTTP, FTP, SFTP and other data transmission protocols. The provincial coordination system has been operational, providing provincial meteorological departments 25 kinds of meteorological data with intelligent grid products and multisource realtime datasets. The average amount of data shared per month is 6.3 T, and the establishment of fullprocess monitoring to ensure the timeliness of data sharing effectively.
2021, 49(6):869-877.
Abstract:
Compared with the observations from 55 Beijing auto weather stations from 1 October 2018 to 30 September 2019, the European Center MediumRange Weather Forecasts Fine Grid Model (ECMWFthin), Regional Assimilation and Prediction System (Grapes), Rapidrefresh Multiscale Analysis and Prediction System - Short Term (RMAPSST), Central Station Guided Forecast (SCMOC), Beijing Intelligent Grid Temperature Objective Prediction Method (BJTM) and Analog Ensemble method (AnEn) which mainly focus on the daily maximum and minimum temperature in the Beijing area are evaluated. (1) In total, the results show that ECMWFthin model performance was better than Grapes and RMAPS; Two objective methods, BJTM and AnEn, had apparent improvement effects on ECMWFthin. (2) AnEn performed well from October 2018 to April 2019, and BJTM performed well from May to September 2019. Regarding different forecast timeliness, AnEn performed well in the shortterm and the first part of mediumterm, BJTM performed well in 5 to 9 days in mediumterm. (3) Focusing on the Guanxiangtai station, the systematic deviation was evident in all three models. Objective methods reduced the systematic deviation of models. (4) Under the background of precipitation, wind and no obvious weather, the two objective methods BJTM and AnEn had significantly improved the forecast quality of the ECMWFthin model for daily maximum temperature. However, when haze weather happened, the forecast accuracy of ECMWFthin was significantly higher than other models and methods. For the minimum daily temperature, except for precipitation weather background, the ECMWFthin model had the smallest deviation, and objective methods slightly improved the model results. Moreover, the RMAPS results showed better performance when precipitation occurred, and objective methods reduced the systematic deviation of the largescale model.
Compared with the observations from 55 Beijing auto weather stations from 1 October 2018 to 30 September 2019, the European Center MediumRange Weather Forecasts Fine Grid Model (ECMWFthin), Regional Assimilation and Prediction System (Grapes), Rapidrefresh Multiscale Analysis and Prediction System - Short Term (RMAPSST), Central Station Guided Forecast (SCMOC), Beijing Intelligent Grid Temperature Objective Prediction Method (BJTM) and Analog Ensemble method (AnEn) which mainly focus on the daily maximum and minimum temperature in the Beijing area are evaluated. (1) In total, the results show that ECMWFthin model performance was better than Grapes and RMAPS; Two objective methods, BJTM and AnEn, had apparent improvement effects on ECMWFthin. (2) AnEn performed well from October 2018 to April 2019, and BJTM performed well from May to September 2019. Regarding different forecast timeliness, AnEn performed well in the shortterm and the first part of mediumterm, BJTM performed well in 5 to 9 days in mediumterm. (3) Focusing on the Guanxiangtai station, the systematic deviation was evident in all three models. Objective methods reduced the systematic deviation of models. (4) Under the background of precipitation, wind and no obvious weather, the two objective methods BJTM and AnEn had significantly improved the forecast quality of the ECMWFthin model for daily maximum temperature. However, when haze weather happened, the forecast accuracy of ECMWFthin was significantly higher than other models and methods. For the minimum daily temperature, except for precipitation weather background, the ECMWFthin model had the smallest deviation, and objective methods slightly improved the model results. Moreover, the RMAPS results showed better performance when precipitation occurred, and objective methods reduced the systematic deviation of the largescale model.
2021, 49(6):878-884.
Abstract:
The evolution characteristics of the wind field at the lowlevel stratosphere are analyzed based on FNL reanalysis data from June to August 2017. After that, highresolution numerical simulations of the wind field at the lowlevel stratosphere are evaluated by sounding data at the Urumqi station. Results show that the temporal transition of the stratosphere zonal wind over the Xinjiang region varied with latitude. Meanwhile, the starting and ending time of the quasizero wind layer also varied with latitude. Starting time of the quasizero wind layer was earlier in the southern region than in the northern region. However, it was the opposite of the ending time. In summer, the quasizero wind layer existed between 70 hPa and 40 hPa over the Xinjiang region. Variation of the quasizero wind layer altitude presented a trend of declining first and then rising later. Results of the numerical simulation of the quasizero wind layer showed that the trends of the quasizero wind layer parameters over time displayed good agreement between simulations and soundings. The mean absolute error of the initial height of the quasizero wind layer was 467 m. The rootmeansquare error of wind speed at the initial height of the quasizero wind layer was 1.75 m/s.
The evolution characteristics of the wind field at the lowlevel stratosphere are analyzed based on FNL reanalysis data from June to August 2017. After that, highresolution numerical simulations of the wind field at the lowlevel stratosphere are evaluated by sounding data at the Urumqi station. Results show that the temporal transition of the stratosphere zonal wind over the Xinjiang region varied with latitude. Meanwhile, the starting and ending time of the quasizero wind layer also varied with latitude. Starting time of the quasizero wind layer was earlier in the southern region than in the northern region. However, it was the opposite of the ending time. In summer, the quasizero wind layer existed between 70 hPa and 40 hPa over the Xinjiang region. Variation of the quasizero wind layer altitude presented a trend of declining first and then rising later. Results of the numerical simulation of the quasizero wind layer showed that the trends of the quasizero wind layer parameters over time displayed good agreement between simulations and soundings. The mean absolute error of the initial height of the quasizero wind layer was 467 m. The rootmeansquare error of wind speed at the initial height of the quasizero wind layer was 1.75 m/s.
2021, 49(6):885-896.
Abstract:
Using the hourly precipitation data from 40 national stations in Hebei Province from 2005 to 2019, the spatial and temporal distribution characteristics of hourly precipitation and heavy hourly precipitation in Hebei Province are analyzed. The results show that: (1) The frequency of hourly precipitation decreased in recent years, while heavy hourly precipitation had no apparent change trend. The monthly changes in hourly precipitation, precipitation frequency, precipitation intensity, and hourly heavy precipitation frequency showed a singlepeak distribution. The hourly heavy precipitation frequency showed a trend of annual differentiation. The differentiation became greater, making the extreme occurrence of hourly heavy precipitation events more prominent. (2) The annual precipitation generally showed a trend of high in the east and low in the west, and high in the south and low in the north. The large value centres were mainly located in the northeast and southwest regions. The frequency and intensity of precipitation were significantly affected by the terrain. The two large value centres of precipitation frequency were located in the northern and centralwestern regions with higher altitude, and that in the plains was lower. However, the area with large precipitation intensity was located in the northeast, caused by the combined influence of the subtropical high and topography. (3) Precipitation in Hebei was mainly concentrated in the evening to night, and the time of peak precipitation appeared to be eastward delayed. Due to the influence of local convective weather in the afternoon, the maximum peak occurred mainly around 17:00 (Beijing time). Hourly heavy precipitation occurred more frequently. (4) The high incidence of heavy hourly precipitation was from July to August, mainly concentrated in the east and south of Hebei. Its maximum value occurred in the northeast and Shijiazhuang. (5) The precipitation in the south was mainly due to the contribution of precipitation intensity. The precipitation in the northern, western mountainous areas and the northwestern Bashang area was more affected by the precipitation frequency; the precipitation in the northeast was caused by the combined effect of precipitation frequency and precipitation intensity.
Using the hourly precipitation data from 40 national stations in Hebei Province from 2005 to 2019, the spatial and temporal distribution characteristics of hourly precipitation and heavy hourly precipitation in Hebei Province are analyzed. The results show that: (1) The frequency of hourly precipitation decreased in recent years, while heavy hourly precipitation had no apparent change trend. The monthly changes in hourly precipitation, precipitation frequency, precipitation intensity, and hourly heavy precipitation frequency showed a singlepeak distribution. The hourly heavy precipitation frequency showed a trend of annual differentiation. The differentiation became greater, making the extreme occurrence of hourly heavy precipitation events more prominent. (2) The annual precipitation generally showed a trend of high in the east and low in the west, and high in the south and low in the north. The large value centres were mainly located in the northeast and southwest regions. The frequency and intensity of precipitation were significantly affected by the terrain. The two large value centres of precipitation frequency were located in the northern and centralwestern regions with higher altitude, and that in the plains was lower. However, the area with large precipitation intensity was located in the northeast, caused by the combined influence of the subtropical high and topography. (3) Precipitation in Hebei was mainly concentrated in the evening to night, and the time of peak precipitation appeared to be eastward delayed. Due to the influence of local convective weather in the afternoon, the maximum peak occurred mainly around 17:00 (Beijing time). Hourly heavy precipitation occurred more frequently. (4) The high incidence of heavy hourly precipitation was from July to August, mainly concentrated in the east and south of Hebei. Its maximum value occurred in the northeast and Shijiazhuang. (5) The precipitation in the south was mainly due to the contribution of precipitation intensity. The precipitation in the northern, western mountainous areas and the northwestern Bashang area was more affected by the precipitation frequency; the precipitation in the northeast was caused by the combined effect of precipitation frequency and precipitation intensity.
2021, 49(6):897-902.
Abstract:
Using the hourly precipitation data of the automatic ground station from 2008 to 2016 with a resolution of 0.1°×0.1°, integrated with the multisatellite precipitation data from the Climate Prediction Center Morphing (CMORPH), the Meiyu season will be divided into three periods: before Meiyu (from May 1st to the day before the Meiyu starting), during Meiyu (from Meiyu starting to Meiyu ending) and after Meiyu (from the day after Meiyu ending to August 31st). This paper analyses the temporal and spatial characteristics of precipitation during the rainy season in the Dabie Mountains area and concludes that: During the rainy season, the average annual precipitation was 360.3 mm, and the average precipitation before and after the rainy season was 279.9 mm, 287.0 mm, respectively. There were three major precipitation areas in the Meiyu season, distributed in the middle section of the north side of the Dabie Mountains, the southeast side and the southwest side of the central peak. The diurnal precipitation variation during the Meiyu period presented a bimodal characteristic, with the peak time at 9 o’clock and 16 o’clock, respectively. The diurnal variation of precipitation before and after the rainy season showed a single peak. The large occurrence probability of heavy precipitation in spatial distribution also gradually rose with the three periods of before Meiyu, during Meiyu and after Meiyu.
Using the hourly precipitation data of the automatic ground station from 2008 to 2016 with a resolution of 0.1°×0.1°, integrated with the multisatellite precipitation data from the Climate Prediction Center Morphing (CMORPH), the Meiyu season will be divided into three periods: before Meiyu (from May 1st to the day before the Meiyu starting), during Meiyu (from Meiyu starting to Meiyu ending) and after Meiyu (from the day after Meiyu ending to August 31st). This paper analyses the temporal and spatial characteristics of precipitation during the rainy season in the Dabie Mountains area and concludes that: During the rainy season, the average annual precipitation was 360.3 mm, and the average precipitation before and after the rainy season was 279.9 mm, 287.0 mm, respectively. There were three major precipitation areas in the Meiyu season, distributed in the middle section of the north side of the Dabie Mountains, the southeast side and the southwest side of the central peak. The diurnal precipitation variation during the Meiyu period presented a bimodal characteristic, with the peak time at 9 o’clock and 16 o’clock, respectively. The diurnal variation of precipitation before and after the rainy season showed a single peak. The large occurrence probability of heavy precipitation in spatial distribution also gradually rose with the three periods of before Meiyu, during Meiyu and after Meiyu.
2021, 49(6):903-912.
Abstract:
With the utilization of FNL reanalysis data, the Temperature of Black Body (TBB) observed by FY2H satellite as well as dualpolarization radar base data, a diagnostic analysis of three warmsector rainstorms occurred in Zhejiang Province in late spring and early summer of 2020 (shorted as “5·25”, “5·29” and “6·2” process respectively) is conducted. The results show that: (1) All the three rainstorm processes occurred under the background of the lowlevel shear line in front of the upper trough. However, the depth of the upper trough, the position of the mesoscale shear line, and the abnormally strong southwest jet pulsating together caused the varying precipitation area and intensity. (2) The rainstorm area deviated from the west side of the wet Qvector convergence. The negative value area of the wet Qvector divergence field at 700 hPa was a good indicator for the rainstorm. (3) There was frontogenesis with a pair of temperature advection centres when the rainstorm occurred. The middlelevel frontogenesis occurred before the low level, and there was a weak temperature advection during the “5·25” process, with shorttime heavy rainfall and low precipitation efficiency. In comparison, the “5·29” and the “6·2” processes both had strong temperature advection, along with longlasting, heavy rainfall and high precipitation efficiency. (4) The rainstorm cloud of “5·25” had a small scale with a short life cycle, and the precipitation was relatively stable, while the cloud was dense. The centroid height of the strong echoes was lower during the “5·29” process, which was biased towards a kind of mixed precipitation dominated by cumulus clouds. However, the centroid height of the strong echoes was higher during the “6·2” process, with αmesoscale convective clouds, large scale cold clouds and columnar echoes, mostly cumulus precipitation.
With the utilization of FNL reanalysis data, the Temperature of Black Body (TBB) observed by FY2H satellite as well as dualpolarization radar base data, a diagnostic analysis of three warmsector rainstorms occurred in Zhejiang Province in late spring and early summer of 2020 (shorted as “5·25”, “5·29” and “6·2” process respectively) is conducted. The results show that: (1) All the three rainstorm processes occurred under the background of the lowlevel shear line in front of the upper trough. However, the depth of the upper trough, the position of the mesoscale shear line, and the abnormally strong southwest jet pulsating together caused the varying precipitation area and intensity. (2) The rainstorm area deviated from the west side of the wet Qvector convergence. The negative value area of the wet Qvector divergence field at 700 hPa was a good indicator for the rainstorm. (3) There was frontogenesis with a pair of temperature advection centres when the rainstorm occurred. The middlelevel frontogenesis occurred before the low level, and there was a weak temperature advection during the “5·25” process, with shorttime heavy rainfall and low precipitation efficiency. In comparison, the “5·29” and the “6·2” processes both had strong temperature advection, along with longlasting, heavy rainfall and high precipitation efficiency. (4) The rainstorm cloud of “5·25” had a small scale with a short life cycle, and the precipitation was relatively stable, while the cloud was dense. The centroid height of the strong echoes was lower during the “5·29” process, which was biased towards a kind of mixed precipitation dominated by cumulus clouds. However, the centroid height of the strong echoes was higher during the “6·2” process, with αmesoscale convective clouds, large scale cold clouds and columnar echoes, mostly cumulus precipitation.
2021, 49(6):913-922.
Abstract:
The Suizhou Sband dualpolarization radar data and conventional observations are used to analyze a supercell in the northern Hubei on 4 May 2020. The results show that: (1) The favourable weather conditions provided the vertical stratification of dry and cold in the upper part and warm and wet in the lower part, moderateintensity vertical wind shear in 0 to 6 km and the surface convergence line. They provided the environmental conditions and trigger conditions for the strong storms. (2) During the supercell development, the front “V” inflow gap, mesocyclone, weak echo dome, drape echo and hook echo were observed. Moreover, the storm top, the centre of storm mass, the height of maximum horizontal reflectivity factor and the VIL showed the trend of first rising and then falling. (3) During the development and maturity of the supercell, a shallow region of high differential reflectivity was found along the large gradient region on the west of forwardflank downdraft below 0 ℃ which was termed as Zdr arc. (4) During the beginning, development and maturity stages of the supercell, a midlevel circular ring of enhanced Zdr and depressed R was found above the 0 ℃ layer, formed by the melting of ice particles due to the positive temperature disturbance strong updraft. (5) In the vertical direction, the Zdr and Kdp columns were observed in the supercell’s beginning, development, and maturity stages. The position of the Zdr column was consistent with a weak echo dome, and its characteristics in different periods reflected the change of updraft intensity; the change of the Kdp column demonstrated the change of liquid droplet region in the supercell.
The Suizhou Sband dualpolarization radar data and conventional observations are used to analyze a supercell in the northern Hubei on 4 May 2020. The results show that: (1) The favourable weather conditions provided the vertical stratification of dry and cold in the upper part and warm and wet in the lower part, moderateintensity vertical wind shear in 0 to 6 km and the surface convergence line. They provided the environmental conditions and trigger conditions for the strong storms. (2) During the supercell development, the front “V” inflow gap, mesocyclone, weak echo dome, drape echo and hook echo were observed. Moreover, the storm top, the centre of storm mass, the height of maximum horizontal reflectivity factor and the VIL showed the trend of first rising and then falling. (3) During the development and maturity of the supercell, a shallow region of high differential reflectivity was found along the large gradient region on the west of forwardflank downdraft below 0 ℃ which was termed as Zdr arc. (4) During the beginning, development and maturity stages of the supercell, a midlevel circular ring of enhanced Zdr and depressed R was found above the 0 ℃ layer, formed by the melting of ice particles due to the positive temperature disturbance strong updraft. (5) In the vertical direction, the Zdr and Kdp columns were observed in the supercell’s beginning, development, and maturity stages. The position of the Zdr column was consistent with a weak echo dome, and its characteristics in different periods reflected the change of updraft intensity; the change of the Kdp column demonstrated the change of liquid droplet region in the supercell.
2021, 49(6):923-929.
Abstract:
Based on the aggregative model CALMET coupled with WRF and performance parameters of the wind turbine, this paper set up the wind turbine icing forecast model by using the Makkonen icing growth model coupled with the ice surface radiation melting model. It could be used to forecast the starting and ending times of wind turbine icing. The wind turbine icing has happened 19 times from December 2012 to December 2013 in Jiugongshan Wind Farm. As the research object, three kinds of prediction schemes were used to forecast the starting and ending time of wind turbine icing, in which forecasts were made one day, two days and three days ahead, respectively. It is found that this model has certain prediction ability for wind turbine icing, and the forecasting accuracy of ice starting time was higher when closer to the ice starting time.
Based on the aggregative model CALMET coupled with WRF and performance parameters of the wind turbine, this paper set up the wind turbine icing forecast model by using the Makkonen icing growth model coupled with the ice surface radiation melting model. It could be used to forecast the starting and ending times of wind turbine icing. The wind turbine icing has happened 19 times from December 2012 to December 2013 in Jiugongshan Wind Farm. As the research object, three kinds of prediction schemes were used to forecast the starting and ending time of wind turbine icing, in which forecasts were made one day, two days and three days ahead, respectively. It is found that this model has certain prediction ability for wind turbine icing, and the forecasting accuracy of ice starting time was higher when closer to the ice starting time.
2021, 49(6):930-941.
Abstract:
Machine learning is the core of artificial intelligence (AI) and one of the fundamental ways to make computers intelligent. With breakthroughs in machine learning algorithms represented by deep learning, artificial intelligence has shown a trend of accelerated development and has been widely used in various industries. Machine learning has significant advantages in computational efficiency, accuracy, portability, coordination, flexibility, and ease of use. The next step will be to change the traditional weather observation mode and accelerate, and improve the processing of weather observation data and the quality of numerical weather prediction and promote the cross integration of earth sciences. In order to better promote the application of AIrelated technologies in meteorology, this paper summarizes the application status of machine learning algorithms from the aspects of meteorological observation, numerical forecast, dangerous weather identification and early warning and satellite data processing.
Machine learning is the core of artificial intelligence (AI) and one of the fundamental ways to make computers intelligent. With breakthroughs in machine learning algorithms represented by deep learning, artificial intelligence has shown a trend of accelerated development and has been widely used in various industries. Machine learning has significant advantages in computational efficiency, accuracy, portability, coordination, flexibility, and ease of use. The next step will be to change the traditional weather observation mode and accelerate, and improve the processing of weather observation data and the quality of numerical weather prediction and promote the cross integration of earth sciences. In order to better promote the application of AIrelated technologies in meteorology, this paper summarizes the application status of machine learning algorithms from the aspects of meteorological observation, numerical forecast, dangerous weather identification and early warning and satellite data processing.
2021, 49(6):942-952.
Abstract:
In order to compare the similarities and differences of the two typical heavy pollution processes in Chengdu from December 2017 to January 2018, the generation and elimination are analyzed from the circulation situation, boundary layer transport and diffusion conditions by using the data of observation meteorological and wind profiler radar. The results show that: (1) Both processes were formed by stagnant weather. The zonal circulation prevailed in the upper layer, and the lower layer was an equal or weak pressure field with multiple layers of temperature inversion. The relative humidity was high at night, the wind speed was low, and the direction was changeable. Near the ground, the dominant wind direction was northwest, and west wind and wind direction affected the regional transport of air pollutants. (2) In the pollution accumulation stage, there was a small wind layer with an average wind speed of less than 2 m·s-1 and variable wind direction in the boundary layer. In the cleaning stage, this feature was not apparent. (3) The refractive index structure constant C2n and vertical velocity can be used as the criteria for vertical diffusion conditions. In the pollution accumulation stage, the height of the highvalue area of C2n was generally 500 to 1500 m, while it was above 3000 m in the removal stage. Meanwhile, the location and durations of the large value area of C2n and the large value area of vertical velocity were basically the same in the removal stage. (4) The recirculation index (RF) and the ventilation index (VI) were very indicative of the pollution process. In the pollution accumulation stage, the RF below 1000 m was less than 0.6, the nearsurface RF was less than 0.2, and the daily average VI was only 1455 m2·s-1. In the removal stage, the RF was above 0.7, and the VI exceeds 3000 m2·s-1. In addition, VI with a large value also played a role in transmitting upstream pollutants.
In order to compare the similarities and differences of the two typical heavy pollution processes in Chengdu from December 2017 to January 2018, the generation and elimination are analyzed from the circulation situation, boundary layer transport and diffusion conditions by using the data of observation meteorological and wind profiler radar. The results show that: (1) Both processes were formed by stagnant weather. The zonal circulation prevailed in the upper layer, and the lower layer was an equal or weak pressure field with multiple layers of temperature inversion. The relative humidity was high at night, the wind speed was low, and the direction was changeable. Near the ground, the dominant wind direction was northwest, and west wind and wind direction affected the regional transport of air pollutants. (2) In the pollution accumulation stage, there was a small wind layer with an average wind speed of less than 2 m·s-1 and variable wind direction in the boundary layer. In the cleaning stage, this feature was not apparent. (3) The refractive index structure constant C2n and vertical velocity can be used as the criteria for vertical diffusion conditions. In the pollution accumulation stage, the height of the highvalue area of C2n was generally 500 to 1500 m, while it was above 3000 m in the removal stage. Meanwhile, the location and durations of the large value area of C2n and the large value area of vertical velocity were basically the same in the removal stage. (4) The recirculation index (RF) and the ventilation index (VI) were very indicative of the pollution process. In the pollution accumulation stage, the RF below 1000 m was less than 0.6, the nearsurface RF was less than 0.2, and the daily average VI was only 1455 m2·s-1. In the removal stage, the RF was above 0.7, and the VI exceeds 3000 m2·s-1. In addition, VI with a large value also played a role in transmitting upstream pollutants.
2021, 49(6):953-959.
Abstract:
In order to study the distribution of effective disastercausing lightning in Fujian Province, based on the lightning location data and lightning casualty data of Fujian Province in 2004-2012, and the L17class Google remote sensing image tiles of Fujian Province, the Convolutional Neural Network (CNN) model is introduced to model, train, and predicts for identifying whether the area where the remote sensing image belongs to is unpopulated. We obtained the grid products of the activity attribute of Fujian Province, combining with the historical lightning data of Fujian Province and analyzed the actual distribution of lightning. The results show that: (1) The designed remote sensing image and CNN identification model had certain feasibility and accuracy, passed the hypothesis test with a significance level of 0.01. (2) 63.55% of the grid points in Fujian Province were in unpopulated areas. (3) An average of 45.36% of lightning fell in unpopulated areas, and early warning and prediction of other disasteraffecting lightning was a feasible way to improve the effectiveness of emergency mitigation services according to local conditions. (4) The correlation between the effective lightning density and the historical lightning casualty data was much greater than that of the conventional lightning density and the historical lightning casualty data, and the distribution of effective lightning was more indicative than the regular lightning distribution.
In order to study the distribution of effective disastercausing lightning in Fujian Province, based on the lightning location data and lightning casualty data of Fujian Province in 2004-2012, and the L17class Google remote sensing image tiles of Fujian Province, the Convolutional Neural Network (CNN) model is introduced to model, train, and predicts for identifying whether the area where the remote sensing image belongs to is unpopulated. We obtained the grid products of the activity attribute of Fujian Province, combining with the historical lightning data of Fujian Province and analyzed the actual distribution of lightning. The results show that: (1) The designed remote sensing image and CNN identification model had certain feasibility and accuracy, passed the hypothesis test with a significance level of 0.01. (2) 63.55% of the grid points in Fujian Province were in unpopulated areas. (3) An average of 45.36% of lightning fell in unpopulated areas, and early warning and prediction of other disasteraffecting lightning was a feasible way to improve the effectiveness of emergency mitigation services according to local conditions. (4) The correlation between the effective lightning density and the historical lightning casualty data was much greater than that of the conventional lightning density and the historical lightning casualty data, and the distribution of effective lightning was more indicative than the regular lightning distribution.
2021, 49(6):960-967.
Abstract:
Based on the hourly ground observation data of 59 national meteorological stations in Liaoning Province from June to August in 2008 to 2017, considering the adverse effects of summer climatic suitability and high impact weather on summer tourism, this paper determines the evaluation method of climate suitability for summer tourism in Liaoning Province, analyzes the temporal and spatial distribution of summer tourism suitability, and provides references for the public and tourism departments to understand the local summer tourism climate resources. The results show that: (1) The suitability of summer tourism in Liaoning Province gradually increased from northwest to southeast. Among the 59 cities in Liaoning Province, 14 were very suitable for summer vacation, 22 were suitable for summer vacation, and 16 were relatively suitable for summer vacation. (2) In summer, most of Liaoning’s summer tourism climatic comfortability showed good, and the climatic comfortability of eastern and southern Liaoning showed better than that of central and western Liaoning. Benxi in the east of Liaoning Province and Dandong, Dalian, Huludao and the south of Jinzhou in the coastal areas had the highest climatic comfortability level and better weather conditions for summer holidays. (3) In summer, the highrisk areas of rainstorms were Kuandian, Dandong and Fengcheng in the Southeast. The highrisk areas of high temperature were in most of Chaoyang and the west of Jinzhou. The highrisk areas of gale were north of Tieling, Zhangwu, Jinzhou, Yingkou and Changhai. The highrisk areas of thunderstorms were Tieling, Eastern Fushun, Western Chaoyang and Zhuanghe in Dalian. (4) June and August were suitable months for summer tourism in Liaoning Province; especially in June, the suitability of summer tourism was the highest, and the suitable area was the largest. The suitability of summer tourism in August showed secondly good, and that in July showed relatively bad.
Based on the hourly ground observation data of 59 national meteorological stations in Liaoning Province from June to August in 2008 to 2017, considering the adverse effects of summer climatic suitability and high impact weather on summer tourism, this paper determines the evaluation method of climate suitability for summer tourism in Liaoning Province, analyzes the temporal and spatial distribution of summer tourism suitability, and provides references for the public and tourism departments to understand the local summer tourism climate resources. The results show that: (1) The suitability of summer tourism in Liaoning Province gradually increased from northwest to southeast. Among the 59 cities in Liaoning Province, 14 were very suitable for summer vacation, 22 were suitable for summer vacation, and 16 were relatively suitable for summer vacation. (2) In summer, most of Liaoning’s summer tourism climatic comfortability showed good, and the climatic comfortability of eastern and southern Liaoning showed better than that of central and western Liaoning. Benxi in the east of Liaoning Province and Dandong, Dalian, Huludao and the south of Jinzhou in the coastal areas had the highest climatic comfortability level and better weather conditions for summer holidays. (3) In summer, the highrisk areas of rainstorms were Kuandian, Dandong and Fengcheng in the Southeast. The highrisk areas of high temperature were in most of Chaoyang and the west of Jinzhou. The highrisk areas of gale were north of Tieling, Zhangwu, Jinzhou, Yingkou and Changhai. The highrisk areas of thunderstorms were Tieling, Eastern Fushun, Western Chaoyang and Zhuanghe in Dalian. (4) June and August were suitable months for summer tourism in Liaoning Province; especially in June, the suitability of summer tourism was the highest, and the suitable area was the largest. The suitability of summer tourism in August showed secondly good, and that in July showed relatively bad.
2021, 49(6):968-974.
Abstract:
Climate change affects lemon growth, yield and quality. In order to study the change of climate suitability distribution of Citrus Lemon in Yunnan under the background of future climate change, the daily meteorological data of 125 national meteorological stations in Yunnan from 1981 to 2018 are used. Based on the climate suitability regionalization of lemon in Yunnan Province, the climate suitability regionalization of lemon in 2021-2030, 2031-2040 and 2041-2050 are studied using RCP2.6, RCP4.5 and RCP8.5 climate scenarios. By the middle of the 21st century, lemon’s most suitable planting area under RCP2.6, RCP4.5 and RCP8.5 increased by about 30%, 50% and 9%, respectively. However, because of the limitation of precipitation factor, the moderate suitable area will decrease from 2041 to 2050, and the total suitable area (high suitable area + medium suitable area) will be stable, providing a broad space for lemon planting development in Yunnan.
Climate change affects lemon growth, yield and quality. In order to study the change of climate suitability distribution of Citrus Lemon in Yunnan under the background of future climate change, the daily meteorological data of 125 national meteorological stations in Yunnan from 1981 to 2018 are used. Based on the climate suitability regionalization of lemon in Yunnan Province, the climate suitability regionalization of lemon in 2021-2030, 2031-2040 and 2041-2050 are studied using RCP2.6, RCP4.5 and RCP8.5 climate scenarios. By the middle of the 21st century, lemon’s most suitable planting area under RCP2.6, RCP4.5 and RCP8.5 increased by about 30%, 50% and 9%, respectively. However, because of the limitation of precipitation factor, the moderate suitable area will decrease from 2041 to 2050, and the total suitable area (high suitable area + medium suitable area) will be stable, providing a broad space for lemon planting development in Yunnan.
2021, 49(6):975-982.
Abstract:
Daily temperature of 88 national meteorological stations in Guangxi from 1960 to 2019 are utilized in the research. The study period is divided into two stages: the first 30 years (P1: 1960-1989) and the last 30 years (P2: 1990-2019). The annual variation of the safe sowing date and safe transplanting date of early rice, safe full heading date and safe maturity date of late rice is analyzed. Differences in safe production dates under different guarantee rates in P1 and P2 stages are compared. The aim is to analyze the impact of climate warming on the safe production dates of doublecropping rice in Guangxi. The results show that: (1) The safe sowing date and safe transplanting date of early rice showed a trend ahead of time. The safe full heading date and safe maturity date of late rice showed a trend of delay. The safe sowing date and safe transplanting dates of 80% and 90% guarantee rates were advanced by two days on average. The safe full heading dates of 80% and 90% guarantee rates were delayed by two days on average. On average, the safe maturity dates of 80% and 90% guarantee rates were delayed by five days and six days separately. (2) The results show that the spatial differences of variation characteristics of safe production dates were significant. The safe sowing date and safe transplanting date advanced by more days (above six days) in the northeast of Guangxi. The safe full heading date was delayed by more days (above six days) in Napo and Jingxi of Baise. The delay days of the safe maturity date were six to ten days in most areas of Guangxi, and the spatial differences were relatively small.
Daily temperature of 88 national meteorological stations in Guangxi from 1960 to 2019 are utilized in the research. The study period is divided into two stages: the first 30 years (P1: 1960-1989) and the last 30 years (P2: 1990-2019). The annual variation of the safe sowing date and safe transplanting date of early rice, safe full heading date and safe maturity date of late rice is analyzed. Differences in safe production dates under different guarantee rates in P1 and P2 stages are compared. The aim is to analyze the impact of climate warming on the safe production dates of doublecropping rice in Guangxi. The results show that: (1) The safe sowing date and safe transplanting date of early rice showed a trend ahead of time. The safe full heading date and safe maturity date of late rice showed a trend of delay. The safe sowing date and safe transplanting dates of 80% and 90% guarantee rates were advanced by two days on average. The safe full heading dates of 80% and 90% guarantee rates were delayed by two days on average. On average, the safe maturity dates of 80% and 90% guarantee rates were delayed by five days and six days separately. (2) The results show that the spatial differences of variation characteristics of safe production dates were significant. The safe sowing date and safe transplanting date advanced by more days (above six days) in the northeast of Guangxi. The safe full heading date was delayed by more days (above six days) in Napo and Jingxi of Baise. The delay days of the safe maturity date were six to ten days in most areas of Guangxi, and the spatial differences were relatively small.
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.