Volume 50,Issue 1,2022 Table of Contents
2022, 50(1):1-8.
DOI: 10.19517/j.1671-6345.20210236
Abstract:
Based on the real-time hourly temperature data of global surface meteorological observation stations and non-meteorological observation stations of the National Meteorological Information Center, a real-time updating quality detection process is designed by applying the monthly threshold, block threshold, zonal threshold and spatial consistency comprehensive detection methods. The global hourly surface temperature data set from 2016 to 2020 is established to provide reliable data support for global forecasting services and scientific researches. The detection results of data in the recent five years show that suspicious and wrong data accounted for 0.85% of the total global data. More suspicious and wrong data in Asia accounted for 1.67% of the data samples in Asia, about 72% of the global suspicious error data, and more data are detected in summer and autumn. About 79% of the suspicious data of nonmeteorological observation stations are detected by the block threshold and spatial consistency method. More than 9% of the suspicious data of observation stations are detected by the station extreme value and spatial consistency method.
Based on the real-time hourly temperature data of global surface meteorological observation stations and non-meteorological observation stations of the National Meteorological Information Center, a real-time updating quality detection process is designed by applying the monthly threshold, block threshold, zonal threshold and spatial consistency comprehensive detection methods. The global hourly surface temperature data set from 2016 to 2020 is established to provide reliable data support for global forecasting services and scientific researches. The detection results of data in the recent five years show that suspicious and wrong data accounted for 0.85% of the total global data. More suspicious and wrong data in Asia accounted for 1.67% of the data samples in Asia, about 72% of the global suspicious error data, and more data are detected in summer and autumn. About 79% of the suspicious data of nonmeteorological observation stations are detected by the block threshold and spatial consistency method. More than 9% of the suspicious data of observation stations are detected by the station extreme value and spatial consistency method.
2022, 50(1):9-20.
DOI: 10.19517/j.1671-6345.20210192
Abstract:
Through the two-year long-term MicroWave Radiometer (MWR) observations at the Beijing National Atmospheric Observation Test Base, the Atmospheric Boundary Layer (ABL) height in this area is retrieved by the potential temperature parcel method. The diurnal and monthly changes of the ABL height are analyzed. Moreover, the ABL heights retrieved by the MWR and radiosonde sounding are compared. The characteristics of the change in the ABL height during the day have a good relationship with the change of sunshine duration. Besides the thermal effect, the vertical wind velocity influences the ABL height. Stronger winds near the surface play an essential role in raising the ABL height, leading to the height of the nocturnal ABL from January to April being significantly higher than that in other months. Due to good daytime atmospheric diffusion conditions in February, March, April, September, and October, the maximum monthly mean ABL height exceeded 3 km in all these months. The maximum monthly mean daytime ABL height was 1461 m, and the minimum monthly mean nocturnal ABL height was 242 m. The mean monthly ABL height in February was the highest in a year, 943 m, and the lowest mean monthly ABL height was in December with a height of 426 m. Since the weather was mostly rainy and cloudy in July and August, the mean monthly ABL height was low in these two months. The inversion results of the MWR data was in good consonance with that of the sounding data. The corresponding Pearson’s correlation coefficient reached 0.874, and the root mean square error was only 300m.
Through the two-year long-term MicroWave Radiometer (MWR) observations at the Beijing National Atmospheric Observation Test Base, the Atmospheric Boundary Layer (ABL) height in this area is retrieved by the potential temperature parcel method. The diurnal and monthly changes of the ABL height are analyzed. Moreover, the ABL heights retrieved by the MWR and radiosonde sounding are compared. The characteristics of the change in the ABL height during the day have a good relationship with the change of sunshine duration. Besides the thermal effect, the vertical wind velocity influences the ABL height. Stronger winds near the surface play an essential role in raising the ABL height, leading to the height of the nocturnal ABL from January to April being significantly higher than that in other months. Due to good daytime atmospheric diffusion conditions in February, March, April, September, and October, the maximum monthly mean ABL height exceeded 3 km in all these months. The maximum monthly mean daytime ABL height was 1461 m, and the minimum monthly mean nocturnal ABL height was 242 m. The mean monthly ABL height in February was the highest in a year, 943 m, and the lowest mean monthly ABL height was in December with a height of 426 m. Since the weather was mostly rainy and cloudy in July and August, the mean monthly ABL height was low in these two months. The inversion results of the MWR data was in good consonance with that of the sounding data. The corresponding Pearson’s correlation coefficient reached 0.874, and the root mean square error was only 300m.
2022, 50(1):21-29.
DOI: 10.19517/j.1671-6345.20210230
Abstract:
The atmospheric humidity profile is a vital factor in studying the complexity of the atmospheric system. The groundbased microwave radiometer (MWR) can continuously observe and retrieve atmospheric humidity profiles up to 10 km with high temporal resolution. These profiles are essential for understanding the changes in the climate system. In order to improve the accuracy of retrieving the atmospheric humidity profile by MWR, this paper uses a time loop neural network model that uses the continuous detected signals of microwave radiometers. Moreover, Ka-band millimetre-wave cloud radar data is employed to improve the inversion accuracy for cloudy data. LSTM neural network is applied as the inversion method to retrieve atmospheric humidity profile, while radiosonde measures relative humidity as truth-value to verify and analyze the inversion effect. This research has also conducted a detailed comparison with classical inversion methods (BP and support vector machine). The average absolute error of the humidity profile and the sounding profile is 9.80%, the root mean square error is 13.85%, and the BP neural network model’s average absolute error is 11.52%. The root mean square error is 15.66%. The comparison proves that the method using temporal information could effectively improve the inversion accuracy, especially for the inversion of relative humidity in the range of 3 to 7 km, where the atmospheric humidity profile distribution is more complicated.
The atmospheric humidity profile is a vital factor in studying the complexity of the atmospheric system. The groundbased microwave radiometer (MWR) can continuously observe and retrieve atmospheric humidity profiles up to 10 km with high temporal resolution. These profiles are essential for understanding the changes in the climate system. In order to improve the accuracy of retrieving the atmospheric humidity profile by MWR, this paper uses a time loop neural network model that uses the continuous detected signals of microwave radiometers. Moreover, Ka-band millimetre-wave cloud radar data is employed to improve the inversion accuracy for cloudy data. LSTM neural network is applied as the inversion method to retrieve atmospheric humidity profile, while radiosonde measures relative humidity as truth-value to verify and analyze the inversion effect. This research has also conducted a detailed comparison with classical inversion methods (BP and support vector machine). The average absolute error of the humidity profile and the sounding profile is 9.80%, the root mean square error is 13.85%, and the BP neural network model’s average absolute error is 11.52%. The root mean square error is 15.66%. The comparison proves that the method using temporal information could effectively improve the inversion accuracy, especially for the inversion of relative humidity in the range of 3 to 7 km, where the atmospheric humidity profile distribution is more complicated.
2022, 50(1):30-36.
DOI: 10.19517/j.1671-6345.20210132
Abstract:
With the rapid development of the Fengyun meteorological satellite project, the number of observation channels is increasing, and time and space resolution is enhanced. The original bit rate has been rising from tens of megabits per second to hundreds of megabits and soon will reach over gigabit. The main task of satellites is to obtain remote sensing data. From a certain point of view, satellites could be valued according to the quality and size of remote sensing data. The most crucial part of the Fengyun satellite observation system and satellite-earth-interface is transmitting original data to the ground station through the radio carrier and accurately demodulating the data from those carriers. And this is also the basis of data processing and services. In order to improve the demodulation performance, this article discusses the principle and method of realizing for following important modules: highspeed digital signal processing technologies, the designing of the overall structure of digital demodulation, and the analyses of carrier recovery, cross-polarization cancellation, clock recovery and equalization. Under laboratory conditions, 8PSK digital demodulation systems have been implemented using VHDL. While the data transmission rate reachs 1.2 Gb/s by adopting 7/8 LDPC decoding. And this strongly verifies the effectiveness and superiority of the design in highspeed digital signal processing. It also provides evidence for the development of the Fengyun satellite and the modulation/demodulation of meteorological satellites in the future.
With the rapid development of the Fengyun meteorological satellite project, the number of observation channels is increasing, and time and space resolution is enhanced. The original bit rate has been rising from tens of megabits per second to hundreds of megabits and soon will reach over gigabit. The main task of satellites is to obtain remote sensing data. From a certain point of view, satellites could be valued according to the quality and size of remote sensing data. The most crucial part of the Fengyun satellite observation system and satellite-earth-interface is transmitting original data to the ground station through the radio carrier and accurately demodulating the data from those carriers. And this is also the basis of data processing and services. In order to improve the demodulation performance, this article discusses the principle and method of realizing for following important modules: highspeed digital signal processing technologies, the designing of the overall structure of digital demodulation, and the analyses of carrier recovery, cross-polarization cancellation, clock recovery and equalization. Under laboratory conditions, 8PSK digital demodulation systems have been implemented using VHDL. While the data transmission rate reachs 1.2 Gb/s by adopting 7/8 LDPC decoding. And this strongly verifies the effectiveness and superiority of the design in highspeed digital signal processing. It also provides evidence for the development of the Fengyun satellite and the modulation/demodulation of meteorological satellites in the future.
2022, 50(1):37-44.
DOI: 10.19517/j.1671-6345.20210137
Abstract:
The existing China Weather Radar Standard Format Base Data analysis tools lack sufficient generality and abstraction in design, which is not convenient for radar data analysis and processing. In order to solve this problem, this paper designs and builds the China Weather Radar Base Data Model based on Unidata’s CDM (Common Data Model) and realizes the access to the Weather Radar Standard Format Base Data at the data model level. Based on the open-source Unidata’s NetCDF Java library and IDV visualization software, a set of Weather Radar Standard Format Base Data content extraction and visual analysis tools based on CDM are formed. As a valuable case, the comparisons of the new and old basic reflectivity data of Guangzhou radar for the evaluation of Doppler Weather Radar Standard Format Base Data are discussed, addressing a significant example. It shows that our researches facilitate the use and promote the operational application of Radar Standard Format Base Data. The research results can also be applied to the operational and scientific research related to Radar Base Data processing and analysis and provide basic support for the application of radar data.
The existing China Weather Radar Standard Format Base Data analysis tools lack sufficient generality and abstraction in design, which is not convenient for radar data analysis and processing. In order to solve this problem, this paper designs and builds the China Weather Radar Base Data Model based on Unidata’s CDM (Common Data Model) and realizes the access to the Weather Radar Standard Format Base Data at the data model level. Based on the open-source Unidata’s NetCDF Java library and IDV visualization software, a set of Weather Radar Standard Format Base Data content extraction and visual analysis tools based on CDM are formed. As a valuable case, the comparisons of the new and old basic reflectivity data of Guangzhou radar for the evaluation of Doppler Weather Radar Standard Format Base Data are discussed, addressing a significant example. It shows that our researches facilitate the use and promote the operational application of Radar Standard Format Base Data. The research results can also be applied to the operational and scientific research related to Radar Base Data processing and analysis and provide basic support for the application of radar data.
2022, 50(1):45-50.
DOI: 10.19517/j.1671-6345.20210177
Abstract:
With the development of information technology application innovation and the integrative process of information system, the government management information system of the China Meteorological Administration is accelerating the implementation of nationalization independent and controllable upgrade iteration. Whether the historical data migration can be smoothly realized becomes a pivotal factor in measuring the success or failure of upgrading. This paper proposes a heterogeneous data migration method based on ElasticSearch, a distributed full-text retrieval framework. Using ElasticSearch’s characteristics of dynamic mapping, distributed scalability and unstructured data processing capability, it can crack the limitations of using traditional methods to migrate massive heterogeneous data. This method has been applied to the national industrialized electronic document system of the China Meteorological Administration and has achieved good practical results. It meets the physical migration needs of historical data to the localization independent and controllable ecology and supports the more flexible secondary use of historical data in the new system.
With the development of information technology application innovation and the integrative process of information system, the government management information system of the China Meteorological Administration is accelerating the implementation of nationalization independent and controllable upgrade iteration. Whether the historical data migration can be smoothly realized becomes a pivotal factor in measuring the success or failure of upgrading. This paper proposes a heterogeneous data migration method based on ElasticSearch, a distributed full-text retrieval framework. Using ElasticSearch’s characteristics of dynamic mapping, distributed scalability and unstructured data processing capability, it can crack the limitations of using traditional methods to migrate massive heterogeneous data. This method has been applied to the national industrialized electronic document system of the China Meteorological Administration and has achieved good practical results. It meets the physical migration needs of historical data to the localization independent and controllable ecology and supports the more flexible secondary use of historical data in the new system.
2022, 50(1):51-58.
DOI: 10.19517/j.1671-6345.20210251
Abstract:
Aiming at a large amount of data query requirements of long-time series, multi-sites and multi-meteorological elements, the supporting capacity of the existing CMISS(China Integrated Meteorological Information Sharing System) is seriously insufficient. In this study, the monthly report data of historical surface meteorological records since the establishment of the meteorological stations in Guangxi and existing Hadoop cluster physical resources are used to redesign the ETL process, construct the Parquet format dataset, and complete HDFS conversion storage. Besides, the Broadcast variable of Spark is embedded to optimize the execution parameters of the Spark cluster, which improves the processing parallelism of the cluster and the association query efficiency of SparkSql. The results show that the maximum compression ratio of the Parquet format data set was more than 95%; the query efficiency of the one-time large amount of data was 1 to 5 times higher than the original and supported high concurrent access, providing effective technical support for the development of various related forecasting services.
Aiming at a large amount of data query requirements of long-time series, multi-sites and multi-meteorological elements, the supporting capacity of the existing CMISS(China Integrated Meteorological Information Sharing System) is seriously insufficient. In this study, the monthly report data of historical surface meteorological records since the establishment of the meteorological stations in Guangxi and existing Hadoop cluster physical resources are used to redesign the ETL process, construct the Parquet format dataset, and complete HDFS conversion storage. Besides, the Broadcast variable of Spark is embedded to optimize the execution parameters of the Spark cluster, which improves the processing parallelism of the cluster and the association query efficiency of SparkSql. The results show that the maximum compression ratio of the Parquet format data set was more than 95%; the query efficiency of the one-time large amount of data was 1 to 5 times higher than the original and supported high concurrent access, providing effective technical support for the development of various related forecasting services.
2022, 50(1):59-65.
DOI: 10.19517/j.1671-6345.20210129
Abstract:
Due to the initiative of communication mode and the broad coverage of users, SMS plays a vital role in releasing emergency early warning. However, the SMS platform built by the meteorological department has limitations in release timeliness, coverage, and positioning release, which cannot meet the rapid and accurate release of early warning information. In this paper, combined with the China Mobile big data platform, a technical solution for the targeted release of early-warning SHORT messages is based on the cellular communication principle. Taking the implementation of this scheme in the Ningxia region as an example, critical technologies such as system layout, data docking, target user screening and targeted release strategy are highlighted. The solution can effectively improve the pertinence and effectiveness of the emergency early warning information.
Due to the initiative of communication mode and the broad coverage of users, SMS plays a vital role in releasing emergency early warning. However, the SMS platform built by the meteorological department has limitations in release timeliness, coverage, and positioning release, which cannot meet the rapid and accurate release of early warning information. In this paper, combined with the China Mobile big data platform, a technical solution for the targeted release of early-warning SHORT messages is based on the cellular communication principle. Taking the implementation of this scheme in the Ningxia region as an example, critical technologies such as system layout, data docking, target user screening and targeted release strategy are highlighted. The solution can effectively improve the pertinence and effectiveness of the emergency early warning information.
Shaanxi Meteorological Observatory
,
Xi’an ; Key Laboratory of EcoEnvironment
,
Meteorology for the Qinling Mountains
,
Loess Plateau
,
Xi’an
,
Shaanxi Meteorological Bureau
,
Xi’an
,
Meteorological Institute of Shaanxi
,
Xi’an
,
Shaanxi Meteorological Observatory
,
Xi’an ; Key Laboratory of EcoEnvironment
,
Meteorology for the Qinling Mountains
,
Loess Plateau
,
Xi’an
,
Shaanxi Meteorological Observatory
,
Xi’an ; Key Laboratory of EcoEnvironment
,
Meteorology for the Qinling Mountains
,
Loess Plateau
,
Xi’an
,
Sichuan Climate Center
,
Chengdu
,
Shaanxi Meteorological Observatory
,
Xi’an
,
Shaanxi Meteorological Observatory
,
Xi’an ; Key Laboratory of EcoEnvironment
,
Meteorology for the Qinling Mountains
,
Loess Plateau
,
Xi’an
2022, 50(1):66-74.
DOI: 10.19517/j.1671-6345.20210029
Abstract:
Based on the data of meteorological stations over Shaanxi Province, NCEP/NCAR and ERA5 global reanalysis data, an in-depth analysis is conducted on the abnormal temperature jump process in the eastern part of Xi’an during the early morning hours of December 10, 2019. The results show that: (1) This night sudden intense warming event developed rapidly and locally. It wasn’t easy to forecast. (2) The dry northwest airflow at 500 hPa and the dry warm air at 850 hPa were beneficial to the sinking adiabatic heating. There was inversion near the surface in Xi’an, which hindered the vertical exchange of atmospheric heat. The 2 m temperature in the east of Xi’an was significantly warmer than that in the surrounding areas. It lasted for a long time, creating favourable conditions for the nighttime warming in this area. (3) In this event, the adiabatic warming effect was strengthened with the eastward movement of the Xinjiang high ridge. The strong warm advection had been maintained in the lower layer of the eastern Xi’an area for a long time. In addition, because of the continuous invasion of weak cold air and the barrier effect of Lishan Mountain, the warm air near the ground in the Lintong area was compressed sharply. Under the four factors, the night temperature in the Lintong area increased significantly. (4) 18 night sudden intense warming cases in the Lintong area are analyzed, and the occurrence criteria are summarized. The correction scheme is put forward and tested combined with the numerical model prediction products. The scheme has a positive correction effect in the Lintong area, providing a reference for the night temperature prediction.
Based on the data of meteorological stations over Shaanxi Province, NCEP/NCAR and ERA5 global reanalysis data, an in-depth analysis is conducted on the abnormal temperature jump process in the eastern part of Xi’an during the early morning hours of December 10, 2019. The results show that: (1) This night sudden intense warming event developed rapidly and locally. It wasn’t easy to forecast. (2) The dry northwest airflow at 500 hPa and the dry warm air at 850 hPa were beneficial to the sinking adiabatic heating. There was inversion near the surface in Xi’an, which hindered the vertical exchange of atmospheric heat. The 2 m temperature in the east of Xi’an was significantly warmer than that in the surrounding areas. It lasted for a long time, creating favourable conditions for the nighttime warming in this area. (3) In this event, the adiabatic warming effect was strengthened with the eastward movement of the Xinjiang high ridge. The strong warm advection had been maintained in the lower layer of the eastern Xi’an area for a long time. In addition, because of the continuous invasion of weak cold air and the barrier effect of Lishan Mountain, the warm air near the ground in the Lintong area was compressed sharply. Under the four factors, the night temperature in the Lintong area increased significantly. (4) 18 night sudden intense warming cases in the Lintong area are analyzed, and the occurrence criteria are summarized. The correction scheme is put forward and tested combined with the numerical model prediction products. The scheme has a positive correction effect in the Lintong area, providing a reference for the night temperature prediction.
2022, 50(1):75-84.
DOI: 10.19517/j.1671-6345.20200439
Abstract:
Using conventional observation and NCEP reanalysis data, the catastrophic freezing weather process (low-temperature process for short) in Guangxi during 2008-2019 are analyzed. The results show that the low-temperature process in Guangxi was divided into stable blocking, weakened blocking, trough-ridge, and fluctuation. The stable blocking process lasted 8 to 15 days, and the rest type was 6 days or less. The cold air constantly supplied from high latitudes and the water vapour transported from low latitudes were two essential factors for continuing the low-temperature process in Guangxi. Water vapour and heat provided by southwest wind at 700 hPa were conducive to melting layer formation and freezing rain. The wide temperature front area and high value of average frontogenetic function were favourable for the long time low-temperature process. There was freezing rain temperature stratification with cloud top temperature of -10 to 0 ℃, low layer cold pad ≤-7 ℃, middle layer melting layer ≥8 ℃ in stable blocking and pure snow temperature stratification with cloud top temperature of -20 to -10 ℃, no melting layer, and low layer cold pad temperature of -10 ℃ in trough-ridge. Path of Low-temperature disturbance (LTD) in stable blocking was “east+west” path, and those of other types were east path. The previous strong LTD had instructive significance. LTD first moved southward from Lake Baikal to the north of Guangxi, then eastward from Lake Balkhash along the plateau’s north in the “east+west” path process. The continuous supplement of LTD in the area of 75°E near Lake Balkhash played an important role. Based on the location of the previous LTD and the circulation, the path and duration of the low-temperature process could be judged preliminarily.
Using conventional observation and NCEP reanalysis data, the catastrophic freezing weather process (low-temperature process for short) in Guangxi during 2008-2019 are analyzed. The results show that the low-temperature process in Guangxi was divided into stable blocking, weakened blocking, trough-ridge, and fluctuation. The stable blocking process lasted 8 to 15 days, and the rest type was 6 days or less. The cold air constantly supplied from high latitudes and the water vapour transported from low latitudes were two essential factors for continuing the low-temperature process in Guangxi. Water vapour and heat provided by southwest wind at 700 hPa were conducive to melting layer formation and freezing rain. The wide temperature front area and high value of average frontogenetic function were favourable for the long time low-temperature process. There was freezing rain temperature stratification with cloud top temperature of -10 to 0 ℃, low layer cold pad ≤-7 ℃, middle layer melting layer ≥8 ℃ in stable blocking and pure snow temperature stratification with cloud top temperature of -20 to -10 ℃, no melting layer, and low layer cold pad temperature of -10 ℃ in trough-ridge. Path of Low-temperature disturbance (LTD) in stable blocking was “east+west” path, and those of other types were east path. The previous strong LTD had instructive significance. LTD first moved southward from Lake Baikal to the north of Guangxi, then eastward from Lake Balkhash along the plateau’s north in the “east+west” path process. The continuous supplement of LTD in the area of 75°E near Lake Balkhash played an important role. Based on the location of the previous LTD and the circulation, the path and duration of the low-temperature process could be judged preliminarily.
2022, 50(1):85-93.
DOI: 10.19517/j.1671-6345.20210059
Abstract:
Using the conventional observation data and automatic regional station hourly precipitation data of Xinjiang in the warm season (May to September) for the past ten years, 468 short-time heavy precipitation processes are counted, and their main weather flow, key environmental parameter characteristics and forecast thresholds are discussed. The conclusions are as follows. The effect systems primarily were the central Asia trough (vortex), West Siberia trough (vortex) and Northwest flow. Among the three, the central Asia trough (vortex) occurred most freguently. The temperature and relative humidity profiles from radiosonde sounding can be classified into four types: type I (air with the whole atmosphere dry), type II (air with upper-layer dry and lower-layer wet), type III (air with upper-layer wet and lower-layer dry), and type IV (air with the whole atmosphere wet). The short-time heavy precipitation occurred most freguently under the atmosphere of type I and type III. The central Asia trough (vortex) processes were mainly type III or type IV. Most cases of the West Siberia trough (vortex) belonged to type I and type II. Type I and type III were in the majority of that under the Northwest flow. The corresponding minimum thresholds of the main environmental parameters for the three flow patterns were: 24.0 ℃, 25.0 ℃, 27.0 ℃ for the temperature difference between 850 hPa and 500 hPa; 3.0 ℃, 2.0 ℃, 2.9 ℃ for the average dew temperature from the ground to 700 hPa; 117 J·Kg-1, 146 J·Kg-1, 103 J·Kg-1 for CAPE; 0.8×10-3s-1, 1.0×10-3s-1, 0.5×10-3s-1 for 0-6 km vertical wind shear. In order to provide technical support to the short-time heavy precipitation nowcasting and warning, the preliminary exploration on main weather flow configuration, potential shortimpending prediction and thresholds are made.
Using the conventional observation data and automatic regional station hourly precipitation data of Xinjiang in the warm season (May to September) for the past ten years, 468 short-time heavy precipitation processes are counted, and their main weather flow, key environmental parameter characteristics and forecast thresholds are discussed. The conclusions are as follows. The effect systems primarily were the central Asia trough (vortex), West Siberia trough (vortex) and Northwest flow. Among the three, the central Asia trough (vortex) occurred most freguently. The temperature and relative humidity profiles from radiosonde sounding can be classified into four types: type I (air with the whole atmosphere dry), type II (air with upper-layer dry and lower-layer wet), type III (air with upper-layer wet and lower-layer dry), and type IV (air with the whole atmosphere wet). The short-time heavy precipitation occurred most freguently under the atmosphere of type I and type III. The central Asia trough (vortex) processes were mainly type III or type IV. Most cases of the West Siberia trough (vortex) belonged to type I and type II. Type I and type III were in the majority of that under the Northwest flow. The corresponding minimum thresholds of the main environmental parameters for the three flow patterns were: 24.0 ℃, 25.0 ℃, 27.0 ℃ for the temperature difference between 850 hPa and 500 hPa; 3.0 ℃, 2.0 ℃, 2.9 ℃ for the average dew temperature from the ground to 700 hPa; 117 J·Kg-1, 146 J·Kg-1, 103 J·Kg-1 for CAPE; 0.8×10-3s-1, 1.0×10-3s-1, 0.5×10-3s-1 for 0-6 km vertical wind shear. In order to provide technical support to the short-time heavy precipitation nowcasting and warning, the preliminary exploration on main weather flow configuration, potential shortimpending prediction and thresholds are made.
2022, 50(1):94-102.
DOI: 10.19517/j.1671-6345.20210218
Abstract:
Based on the HYSPLIT model, a Lagrangian particle dispersion model, combined with E-R (evaporation minus precipitation) diagnostics and the related quantitative analysis method of water vapour contribution, the water vapour source and transport characteristics of extreme precipitation in Shandong Province affected by Rumbia (August 2018) are diagnosed. Results indicate that the occurrence of extreme precipitation was related to global water vapour transport and convergence. The water vapour of extreme precipitation mainly came from the regions of the Indian Ocean-Bay of Bengal-South China Sea, the lowlatitude western Pacific, the Mid-latitude Northwest Pacific and Eastern China. The low-latitude western Pacific made the largest contribution, followed by the Mid-latitude Northwest Pacific, while the Indian Ocean-Bay of Bengal-South China Sea and Eastern China both contributed similar amounts that were less than those from the Mid-latitude Northwest Pacific. Besides, by comparing with differences of water vapour transport in different source regions, it is found that although the uptake from the region of the Indian Ocean-Bay of Bengal-South China Sea was relatively high, its ultimate contribution to the target precipitation was dramatically reduced due to evaporation in the air parcels. Despite the uptake from the Mid-latitude Northwest Pacific and Eastern China were relatively low. Still, moisture loss in transit was also small, and the released proportion from the former was higher, so their contribution cannot be ignored.
Based on the HYSPLIT model, a Lagrangian particle dispersion model, combined with E-R (evaporation minus precipitation) diagnostics and the related quantitative analysis method of water vapour contribution, the water vapour source and transport characteristics of extreme precipitation in Shandong Province affected by Rumbia (August 2018) are diagnosed. Results indicate that the occurrence of extreme precipitation was related to global water vapour transport and convergence. The water vapour of extreme precipitation mainly came from the regions of the Indian Ocean-Bay of Bengal-South China Sea, the lowlatitude western Pacific, the Mid-latitude Northwest Pacific and Eastern China. The low-latitude western Pacific made the largest contribution, followed by the Mid-latitude Northwest Pacific, while the Indian Ocean-Bay of Bengal-South China Sea and Eastern China both contributed similar amounts that were less than those from the Mid-latitude Northwest Pacific. Besides, by comparing with differences of water vapour transport in different source regions, it is found that although the uptake from the region of the Indian Ocean-Bay of Bengal-South China Sea was relatively high, its ultimate contribution to the target precipitation was dramatically reduced due to evaporation in the air parcels. Despite the uptake from the Mid-latitude Northwest Pacific and Eastern China were relatively low. Still, moisture loss in transit was also small, and the released proportion from the former was higher, so their contribution cannot be ignored.
2022, 50(1):103-113.
DOI: 10.19517/j.1671-6345.20210049
Abstract:
By using hourly rainfall data of 1426 national stations and regional stations in the warm season (from May to September) in Zhejiang Province from 2010 to 2019 and NCEP 1°×1° reanalysis data four times a day, the short-term heavy rainfall, the extreme short-term heavy rainfall, regional short-term heavy rainfall events in the warm season are analyzed. The results show that: (1) In recent ten years, the interannual variation of short-term heavy precipitation frequency in the warm season showed an increasing trend; and the variation of precipitation intensity was stable. The precipitation frequency was the highest in early August. The intensity was the strongest in middle September. The precipitation frequency was the highest from 16:00 to 19:00, and the intensity was the highest at 16:00 and 20:00. The spatial distribution of short-term heavy rainfall frequency and intensity was closely related to the topography, and short-term heavy rains were prone to occur in the mountainous areas of coastal areas. (2) In recent ten years, the frequency of extreme short-term heavy precipitation in the warm season had great interannual variation. Still, the annual variation trend was stable. The precipitation frequency was the highest in late August, and the precipitation intensity was the highest in middle and late September, while the precipitation frequency at 16:00 was the highest. The precipitation intensity at 12:00 was the highest. The spatial distribution of extreme short-term strong precipitation frequency was also related to the topography, and the frequence in the coastal area was greater than in inland. (3) Regional short-term heavy precipitation events could be divided into cold shear, warm shear, tropical cyclone, high trough, and subtropical high control types.
By using hourly rainfall data of 1426 national stations and regional stations in the warm season (from May to September) in Zhejiang Province from 2010 to 2019 and NCEP 1°×1° reanalysis data four times a day, the short-term heavy rainfall, the extreme short-term heavy rainfall, regional short-term heavy rainfall events in the warm season are analyzed. The results show that: (1) In recent ten years, the interannual variation of short-term heavy precipitation frequency in the warm season showed an increasing trend; and the variation of precipitation intensity was stable. The precipitation frequency was the highest in early August. The intensity was the strongest in middle September. The precipitation frequency was the highest from 16:00 to 19:00, and the intensity was the highest at 16:00 and 20:00. The spatial distribution of short-term heavy rainfall frequency and intensity was closely related to the topography, and short-term heavy rains were prone to occur in the mountainous areas of coastal areas. (2) In recent ten years, the frequency of extreme short-term heavy precipitation in the warm season had great interannual variation. Still, the annual variation trend was stable. The precipitation frequency was the highest in late August, and the precipitation intensity was the highest in middle and late September, while the precipitation frequency at 16:00 was the highest. The precipitation intensity at 12:00 was the highest. The spatial distribution of extreme short-term strong precipitation frequency was also related to the topography, and the frequence in the coastal area was greater than in inland. (3) Regional short-term heavy precipitation events could be divided into cold shear, warm shear, tropical cyclone, high trough, and subtropical high control types.
2022, 50(1):114-120.
DOI: 10.19517/j.1671-6345.20210035
Abstract:
In order to improve the trend of abnormal data, the extra period that the revision of the 10-year interval may introduce, the consistency of the El Nino/La Nina event monitoring index and the change of the event attribute and strength caused by the change of the climate standard value which are recommended by the meteorological industry-standard (national standard), this paper constructs correlation indices based on an anomaly calculation method that can eliminate the first-order trend and discard the climate standard values. The results show that the index calculated by the scheme is in good consistency with the original method. In the series with the significant trend, the algorithm of this scheme is simpler than the meteorological industry standard recommended scheme, and the trend resolution is significant. This scheme may have promotion value in dealing with climate warming and other problems.
In order to improve the trend of abnormal data, the extra period that the revision of the 10-year interval may introduce, the consistency of the El Nino/La Nina event monitoring index and the change of the event attribute and strength caused by the change of the climate standard value which are recommended by the meteorological industry-standard (national standard), this paper constructs correlation indices based on an anomaly calculation method that can eliminate the first-order trend and discard the climate standard values. The results show that the index calculated by the scheme is in good consistency with the original method. In the series with the significant trend, the algorithm of this scheme is simpler than the meteorological industry standard recommended scheme, and the trend resolution is significant. This scheme may have promotion value in dealing with climate warming and other problems.
2022, 50(1):121-128.
DOI: 10.19517/j.1671-6345.20210210
Abstract:
In order to reduce personal casualties and economic losses caused by lightning disasters, a lightning nowcasting method based on the ADASYN-ET model is proposed. Using four single-station ground meteorological elements of temperature, pressure, humidity and wind combined with ADTD ground-flash location information, a lightning nowcasting method based on the ADASYN-ET model is constructed through the combined application of machine learning techniques such as feature engineering, resampling, and cross-validation, which can provide 0 to 30 min advance warning for the 20 km range of weather stations. The validation results show that the warning method applies to all 8 test sites, and the average F1 Score is 0.60, 0.59 and 0.60, 0 to 10 min, 10 to 20 min and 20 to 30 min in advance. The method is flexible compared to other recent warning methods and systems for implementation and can provide references for the work of lightning prevention and disaster reduction.
In order to reduce personal casualties and economic losses caused by lightning disasters, a lightning nowcasting method based on the ADASYN-ET model is proposed. Using four single-station ground meteorological elements of temperature, pressure, humidity and wind combined with ADTD ground-flash location information, a lightning nowcasting method based on the ADASYN-ET model is constructed through the combined application of machine learning techniques such as feature engineering, resampling, and cross-validation, which can provide 0 to 30 min advance warning for the 20 km range of weather stations. The validation results show that the warning method applies to all 8 test sites, and the average F1 Score is 0.60, 0.59 and 0.60, 0 to 10 min, 10 to 20 min and 20 to 30 min in advance. The method is flexible compared to other recent warning methods and systems for implementation and can provide references for the work of lightning prevention and disaster reduction.
2022, 50(1):129-138.
DOI: 10.19517/j.1671-6345.20210040
Abstract:
Based on the B-P formula, Rusck formula and the Agrawal coupling model, we developed a time-domain method for lightning-induced voltages in overhead lines. Using this method, we studied the effects of different parameters on lightning-induced voltages and validated its accuracy using the 2-D FDTD method. The results show that: (1) The induced overvoltage generated by the first return current had a larger peak value and smaller wave head steepness. However, the induced overvoltage generated by the subsequent return current had a smaller peak value and larger wave head steepness. (2) Ground conductivity greatly influenced the amplitude and polarity of induced overvoltage. The peak value of induced overvoltage at the line centre negatively was correlated with ground conductivity. However, at the line end, the peak value of induced overvoltage positively was correlated with ground conductivity, and the waveform showed bipolar characteristics at poor ground conductivity condition (σ=0.001 S/m). (3) Both at the line centre and ends, the peak value of induced overvoltage increased with the line height. (4) Within distances from 50 to 1000 m from the lightning channel, the voltage waveforms calculated by our method were consistent with the 2-D FDTD results and the calculation error was less than 5%. In conclusion, because the calculation time of our method only needs 10 s with high calculation precision, it is very beneficial to be applied in lightning protection engineering.
Based on the B-P formula, Rusck formula and the Agrawal coupling model, we developed a time-domain method for lightning-induced voltages in overhead lines. Using this method, we studied the effects of different parameters on lightning-induced voltages and validated its accuracy using the 2-D FDTD method. The results show that: (1) The induced overvoltage generated by the first return current had a larger peak value and smaller wave head steepness. However, the induced overvoltage generated by the subsequent return current had a smaller peak value and larger wave head steepness. (2) Ground conductivity greatly influenced the amplitude and polarity of induced overvoltage. The peak value of induced overvoltage at the line centre negatively was correlated with ground conductivity. However, at the line end, the peak value of induced overvoltage positively was correlated with ground conductivity, and the waveform showed bipolar characteristics at poor ground conductivity condition (σ=0.001 S/m). (3) Both at the line centre and ends, the peak value of induced overvoltage increased with the line height. (4) Within distances from 50 to 1000 m from the lightning channel, the voltage waveforms calculated by our method were consistent with the 2-D FDTD results and the calculation error was less than 5%. In conclusion, because the calculation time of our method only needs 10 s with high calculation precision, it is very beneficial to be applied in lightning protection engineering.
2022, 50(1):139-146.
DOI: 10.19517/j.1671-6345.20210167
Abstract:
Based on the lightning location detection data of Zhejiang Province from 2016 to 2020, the return-stroke characteristics of cloud-to-ground flashes in the land of Zhejiang Province and Zhoushan sea area are statistically analysed by using Access and MATLAB. The results are as follows: the annual average density of cloud-to-ground flash return strokes in Zhejiang Province is 1.97 fl·km-2·a-1; the density of positive cloud-to-ground flash return strokes is 0.10 fl·km-2·a-1; the positive cloud-to-ground flash return strokes accounted for 5.1% of the total cloud-to-ground flash return strokes; the average current intensity of positive cloud-to-ground flash return strokes is 42.49 kA; the average current intensity of negative cloud-to-ground flashes return strokes is 33.61 kA; the positive and negative current intensity ratio is 1.26; the annual average density of cloud-to-ground flash return strokes in the Zhoushan sea area is 0.54 fl·km-2·a-1; the density of positive cloud-to-ground flashes return strokes is 0.06 fl·km-2·a-1; the positive cloud-to-ground flash return strokes accounted for 11.1% of the total cloud-to-ground flash return strokes; the average current intensity of positive cloud-to-ground flash return strokes is 49.81 kA; the negative cloud-to-ground flash return strokes is 47.77 kA; and the positive and negative current intensity ratio is 1.04. The positive and negative return stroke currents in the northern region of Zhejiang Province and Zhoushan sea area are significantly stronger than those in the southern region. The average positive and negative return stroke current intensities in the Zhoushan sea area are stronger than those in the land of Zhejiang Province. The ratio of positive and negative return stroke current intensities in the Zhoushan sea area is significantly smaller than that in the land of Zhejiang Province. The ratio of average current intensities between positive and negative cloud-to-ground flash return strokes is quite different in different regions. The proportion of positive cloud-to-ground flash return strokes is particularly high in the Zhoushan sea area. The average current intensity of positive cloud-to-ground flash return strokes is slightly higher than negative, the causes of which are preliminarily explained by analysing atmospheric electricity and meteorology.
Based on the lightning location detection data of Zhejiang Province from 2016 to 2020, the return-stroke characteristics of cloud-to-ground flashes in the land of Zhejiang Province and Zhoushan sea area are statistically analysed by using Access and MATLAB. The results are as follows: the annual average density of cloud-to-ground flash return strokes in Zhejiang Province is 1.97 fl·km-2·a-1; the density of positive cloud-to-ground flash return strokes is 0.10 fl·km-2·a-1; the positive cloud-to-ground flash return strokes accounted for 5.1% of the total cloud-to-ground flash return strokes; the average current intensity of positive cloud-to-ground flash return strokes is 42.49 kA; the average current intensity of negative cloud-to-ground flashes return strokes is 33.61 kA; the positive and negative current intensity ratio is 1.26; the annual average density of cloud-to-ground flash return strokes in the Zhoushan sea area is 0.54 fl·km-2·a-1; the density of positive cloud-to-ground flashes return strokes is 0.06 fl·km-2·a-1; the positive cloud-to-ground flash return strokes accounted for 11.1% of the total cloud-to-ground flash return strokes; the average current intensity of positive cloud-to-ground flash return strokes is 49.81 kA; the negative cloud-to-ground flash return strokes is 47.77 kA; and the positive and negative current intensity ratio is 1.04. The positive and negative return stroke currents in the northern region of Zhejiang Province and Zhoushan sea area are significantly stronger than those in the southern region. The average positive and negative return stroke current intensities in the Zhoushan sea area are stronger than those in the land of Zhejiang Province. The ratio of positive and negative return stroke current intensities in the Zhoushan sea area is significantly smaller than that in the land of Zhejiang Province. The ratio of average current intensities between positive and negative cloud-to-ground flash return strokes is quite different in different regions. The proportion of positive cloud-to-ground flash return strokes is particularly high in the Zhoushan sea area. The average current intensity of positive cloud-to-ground flash return strokes is slightly higher than negative, the causes of which are preliminarily explained by analysing atmospheric electricity and meteorology.
2022, 50(1):147-154.
DOI: 10.19517/j.1671-6345.20210196
Abstract:
In order to improve the brand effect and market competitiveness of Putian Wendan pomelo, the climatic quality evaluation targets are built by analyzing the key meteorological factors and major meteorological disasters affecting the fruit quality based on the observational data of regional automatic stations over the years, and quality test data in pomelo’s planting area. Using the expert scoring method and analytic hierarchy process, the weights of climatic suitability factors and hazard inducing factors are determined. The climatic quality evaluation model is established, and the climatic quality index is calculated and quantitatively graded to carry out the climatic quality assessment. The results show that simulative results of the climatic quality evaluation model based on climatic suitability indicators and meteorological disaster ones can quantitatively reflect the impact of meteorological conditions on the quality. Compared with the actual fruit quality, fruit quality in typically historical years and fruit quality in different altitudes, the climatic quality evaluation results are highly consistent with fruit quality and can reflect the actual quality fairly. The evaluation model and results are objective, which can provide technical support for the climatic quality authentication of Putian Wendan pomelo.
In order to improve the brand effect and market competitiveness of Putian Wendan pomelo, the climatic quality evaluation targets are built by analyzing the key meteorological factors and major meteorological disasters affecting the fruit quality based on the observational data of regional automatic stations over the years, and quality test data in pomelo’s planting area. Using the expert scoring method and analytic hierarchy process, the weights of climatic suitability factors and hazard inducing factors are determined. The climatic quality evaluation model is established, and the climatic quality index is calculated and quantitatively graded to carry out the climatic quality assessment. The results show that simulative results of the climatic quality evaluation model based on climatic suitability indicators and meteorological disaster ones can quantitatively reflect the impact of meteorological conditions on the quality. Compared with the actual fruit quality, fruit quality in typically historical years and fruit quality in different altitudes, the climatic quality evaluation results are highly consistent with fruit quality and can reflect the actual quality fairly. The evaluation model and results are objective, which can provide technical support for the climatic quality authentication of Putian Wendan pomelo.
2022, 50(1):155-160.
DOI: 10.19517/j.1671-6345.20210119
Abstract:
Based on the influence of temperature on the growth and development of walnut from germination to young fruit stage, the membership function for the suitability model of daily average temperature is established. The daily minimum temperature, lethal temperature, disaster-causing temperature and the duration below the disaster-causing temperature were introduced into the temperature membership function, and the membership function for the suitability model of daily minimum temperature is established. According to a certain weight combination, the membership function for the suitability model of temperature from germination to young fruit stage of walnut in Taihang mountain area of Hebei Province is constructed. The calculation and analysis based on the model show that when freezing injury occurs, the daily average temperature suitability is generally below 0.8, and the daily minimum temperature suitability and comprehensive temperature suitability are generally below 0.6. The grade of freezing injury is divided according to the value of comprehensive suitability of temperature (S): 0.5<S≤0.6, slight freezing injury; 0.4<S≤0.5, mild freezing injury; 0.1<S≤0.4, moderate freezing injury; S≤0.1, severe freezing injury. Combined with many years of investigation and historical meteorological data, the accuracy of determining the frost damage level based on the comprehensive temperature suitability is 84%. The suitability model better reflects the influence of temperature on the suitability of walnut growth. Combined with the application of intelligent grid numerical prediction, the model will provide some services reference for early warning on freezing injury monitoring in the forest and fruit industry.
Based on the influence of temperature on the growth and development of walnut from germination to young fruit stage, the membership function for the suitability model of daily average temperature is established. The daily minimum temperature, lethal temperature, disaster-causing temperature and the duration below the disaster-causing temperature were introduced into the temperature membership function, and the membership function for the suitability model of daily minimum temperature is established. According to a certain weight combination, the membership function for the suitability model of temperature from germination to young fruit stage of walnut in Taihang mountain area of Hebei Province is constructed. The calculation and analysis based on the model show that when freezing injury occurs, the daily average temperature suitability is generally below 0.8, and the daily minimum temperature suitability and comprehensive temperature suitability are generally below 0.6. The grade of freezing injury is divided according to the value of comprehensive suitability of temperature (S): 0.5<S≤0.6, slight freezing injury; 0.4<S≤0.5, mild freezing injury; 0.1<S≤0.4, moderate freezing injury; S≤0.1, severe freezing injury. Combined with many years of investigation and historical meteorological data, the accuracy of determining the frost damage level based on the comprehensive temperature suitability is 84%. The suitability model better reflects the influence of temperature on the suitability of walnut growth. Combined with the application of intelligent grid numerical prediction, the model will provide some services reference for early warning on freezing injury monitoring in the forest and fruit industry.
External LinksChina Meteorological AdministrationCMA Meteorological Observation CentreChinese Academy of Meteorological SciencesBeijing Meteorological ServiceNational Satellite Meteorological Center
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.