Volume 50,Issue 3,2022 Table of Contents
2022, 50(3):303-313.
DOI: 10.19517/j.1671-6345.20210536
Abstract:
Based on the data of Doppler weather radars, automatic weather stations, radiosondes and satellites, the characteristics of clear air echoes in terms of reflectivity are analyzed using weather radar reflectivity factor and meteorological elements. The results show that the clear air echoes in different regions of China (North China, Central China, East China and South China) have obvious diurnal and annual variations. The specific performance is that the weather radar in the spring and autumn can detect obvious clear air echoes, which mainly appear between the evening and the following day. Further analysis shows that the clear air echoes detected by radars are closely related to the refractive index fluctuation. In addition, the presence of the inversion layer and the high-humidity region also has a high correlation with clear air echoes detected by weather radars.
Based on the data of Doppler weather radars, automatic weather stations, radiosondes and satellites, the characteristics of clear air echoes in terms of reflectivity are analyzed using weather radar reflectivity factor and meteorological elements. The results show that the clear air echoes in different regions of China (North China, Central China, East China and South China) have obvious diurnal and annual variations. The specific performance is that the weather radar in the spring and autumn can detect obvious clear air echoes, which mainly appear between the evening and the following day. Further analysis shows that the clear air echoes detected by radars are closely related to the refractive index fluctuation. In addition, the presence of the inversion layer and the high-humidity region also has a high correlation with clear air echoes detected by weather radars.
2022, 50(3):314-323.
DOI: 10.19517/j.1671-6345.20210229
Abstract:
Cloud radar is a powerful instrument for cloud detection. However, the parameters of the radar transmitter and receiver system can drift during operation, which will cause the overall offset error of the observation data and affect the accuracy of cloud physical property retrieval. Therefore, cloud radar data need to be periodically calibrated properly. This paper uses the radar data calibration method proposed by Pavlos et al., which optimizes weak clouds and precipitation signal recognition. It also uses CloudSat satellite-borne radar observations of reflectivity factors, gas attenuation correction and other data to improve the data quality of the Ka-band Zenith Radar (KAZR) deployed at the Semi-arid Climate and Environment Observatory site (35.57°N, 104.08°E) of Lanzhou University (SACOL). It has established a 46-month historical data calibration from August 2013 to May 2017 for the KAZR radar reflectivity. That means calibration of cloud radar reflectivity data is essential for obtaining accurate cloud macro- and micro-physical properties, providing a solid foundation for long-term clouds study at the SACOL site.
Cloud radar is a powerful instrument for cloud detection. However, the parameters of the radar transmitter and receiver system can drift during operation, which will cause the overall offset error of the observation data and affect the accuracy of cloud physical property retrieval. Therefore, cloud radar data need to be periodically calibrated properly. This paper uses the radar data calibration method proposed by Pavlos et al., which optimizes weak clouds and precipitation signal recognition. It also uses CloudSat satellite-borne radar observations of reflectivity factors, gas attenuation correction and other data to improve the data quality of the Ka-band Zenith Radar (KAZR) deployed at the Semi-arid Climate and Environment Observatory site (35.57°N, 104.08°E) of Lanzhou University (SACOL). It has established a 46-month historical data calibration from August 2013 to May 2017 for the KAZR radar reflectivity. That means calibration of cloud radar reflectivity data is essential for obtaining accurate cloud macro- and micro-physical properties, providing a solid foundation for long-term clouds study at the SACOL site.
3 Research on Influence of Rainfall Intensity on Accuracy of Wind Observation Based on Doppler Lidar
CHEN Quan
,
SHI Wenhao
,
TANG Jie
,
ZHAO Bingke
,
CHEN Xujie
,
CHEN Yonghang
,
LIN Limin
,
YAN Jiaming
,
MA Xiaojun
,
LUO Mengjie
2022, 50(3):324-333.
DOI: 10.19517/j.1671-6345.20210373
Abstract:
Doppler wind lidar has been increasingly widely used in various fields such as atmosphere, environment and wind energy in recent years, but the applicability of Doppler wind lidar under complex weather still needs to be studied in depth. In this study, the wind data from the ground-based lidar in Sansha, Fujian Province, is compared with the wind field data observed from August to October 2020 by the ultrasonic wind thermometer on board the boundary layer tower. It is found that the Doppler wind lidar has stable and high accuracy detection performance in horizontal wind speed and wind direction, and the correlation coefficients between the Doppler wind lidar and the ultrasonic wind thermometer reach 0.948 and 0.984. In contrast, the detection error of vertical wind speed observed by the Doppler wind lidar is higher than that of the ultrasonic wind thermometer. The vertical wind speed correlation coefficient from the Doppler wind lidar and the ultrasonic anemometer is only 0.353. It is found that the vertical wind speed error from Doppler wind lidar is correlated with the rainfall intensity, and the maximum vertical wind speed deviation could reach 9 m·s-1 under strong rainfall.
Doppler wind lidar has been increasingly widely used in various fields such as atmosphere, environment and wind energy in recent years, but the applicability of Doppler wind lidar under complex weather still needs to be studied in depth. In this study, the wind data from the ground-based lidar in Sansha, Fujian Province, is compared with the wind field data observed from August to October 2020 by the ultrasonic wind thermometer on board the boundary layer tower. It is found that the Doppler wind lidar has stable and high accuracy detection performance in horizontal wind speed and wind direction, and the correlation coefficients between the Doppler wind lidar and the ultrasonic wind thermometer reach 0.948 and 0.984. In contrast, the detection error of vertical wind speed observed by the Doppler wind lidar is higher than that of the ultrasonic wind thermometer. The vertical wind speed correlation coefficient from the Doppler wind lidar and the ultrasonic anemometer is only 0.353. It is found that the vertical wind speed error from Doppler wind lidar is correlated with the rainfall intensity, and the maximum vertical wind speed deviation could reach 9 m·s-1 under strong rainfall.
2022, 50(3):334-343.
DOI: 10.19517/j.1671-6345.20210332
Abstract:
The Velocity Azimuth Display (VAD) winds provide wind field information with high temporal resolution. A quality control scheme, called the NMIC scheme, is developed for VAD winds from CINRAD Doppler radar, which improves the NCEP CQCVAD scheme. Compared with L-band sounding winds, the VAD data after the NMIC scheme is more accurate than those after the NCEP CQCVAD scheme and the data before quality control. The bias and root mean square error of the VAD data after the NMIC scheme are smaller than those after the NCEP CQCVAD scheme and the data before quality control at most height levels, which confirms the validity of the NMIC scheme. The VAD winds after quality control are also compared with the background. The distribution of the deviation between background and the VAD data after the NMIC scheme fits the Gaussian distribution better than the NCEP CQCVAD scheme. The results reveal that the VAD data after the NMIC scheme can meet the quality control requirements for data assimilation. This study would support and further improve the application of VAD winds in the numerical weather forecast.
The Velocity Azimuth Display (VAD) winds provide wind field information with high temporal resolution. A quality control scheme, called the NMIC scheme, is developed for VAD winds from CINRAD Doppler radar, which improves the NCEP CQCVAD scheme. Compared with L-band sounding winds, the VAD data after the NMIC scheme is more accurate than those after the NCEP CQCVAD scheme and the data before quality control. The bias and root mean square error of the VAD data after the NMIC scheme are smaller than those after the NCEP CQCVAD scheme and the data before quality control at most height levels, which confirms the validity of the NMIC scheme. The VAD winds after quality control are also compared with the background. The distribution of the deviation between background and the VAD data after the NMIC scheme fits the Gaussian distribution better than the NCEP CQCVAD scheme. The results reveal that the VAD data after the NMIC scheme can meet the quality control requirements for data assimilation. This study would support and further improve the application of VAD winds in the numerical weather forecast.
2022, 50(3):344-354.
DOI: 10.19517/j.1671-6345.20210364
Abstract:
Based on the microwave radiometer and radiosonde data from January 2018 to December 2019 in the central and southern Hebei Province, this paper makes point-to-point matching of the data obtained by the two kinds of detection equipment in time and space. A total of 187 clear sky profiles, 1176 cloud sky profiles and 12 drizzle sky profiles are screened. The correlation and error of the temperature, relative humidity, and water vapour density profiles are quantitatively analysed from the two kinds of atmospheric detection equipment under the clear sky, cloud sky, and drizzle weather conditions in each altitude layer. The results show that temperature and water vapour density correlation between microwave radiometer and radiosonde is desirable. The distributions of atmospheric parameters observed by ground-based microwave radiometer are different. Still, the trends of microwave radiometers and radiosonde are consistent. The correlation between the atmospheric parameters observed by radiosonde and the temperature, relative humidity and water vapour density retrieved by microwave radiometer shows that the results in the lower atmosphere is better than those in the upper atmosphere; the temperature correlation is the best, the water vapour density is the second and the relative humidity is the lowest. By comparing the fitting degree of each altitude layer, it is found that the accuracy of atmospheric parameters below 3.5 km is more reliable. For the atmospheric physical quantities that need to be calculated indirectly, such as K-index, effective potential energy, integral water content, etc., the accuracy of atmospheric physical quantities calculated by using low-level data is better. The comparison of atmospheric physical parameters retrieved by ground-based microwave radiometers and radiosonde observation in this paper has reference significance for improving the detection accuracy of microwave radiometers in Atmospheric Physics and weather modification researches.
Based on the microwave radiometer and radiosonde data from January 2018 to December 2019 in the central and southern Hebei Province, this paper makes point-to-point matching of the data obtained by the two kinds of detection equipment in time and space. A total of 187 clear sky profiles, 1176 cloud sky profiles and 12 drizzle sky profiles are screened. The correlation and error of the temperature, relative humidity, and water vapour density profiles are quantitatively analysed from the two kinds of atmospheric detection equipment under the clear sky, cloud sky, and drizzle weather conditions in each altitude layer. The results show that temperature and water vapour density correlation between microwave radiometer and radiosonde is desirable. The distributions of atmospheric parameters observed by ground-based microwave radiometer are different. Still, the trends of microwave radiometers and radiosonde are consistent. The correlation between the atmospheric parameters observed by radiosonde and the temperature, relative humidity and water vapour density retrieved by microwave radiometer shows that the results in the lower atmosphere is better than those in the upper atmosphere; the temperature correlation is the best, the water vapour density is the second and the relative humidity is the lowest. By comparing the fitting degree of each altitude layer, it is found that the accuracy of atmospheric parameters below 3.5 km is more reliable. For the atmospheric physical quantities that need to be calculated indirectly, such as K-index, effective potential energy, integral water content, etc., the accuracy of atmospheric physical quantities calculated by using low-level data is better. The comparison of atmospheric physical parameters retrieved by ground-based microwave radiometers and radiosonde observation in this paper has reference significance for improving the detection accuracy of microwave radiometers in Atmospheric Physics and weather modification researches.
2022, 50(3):355-360.
DOI: 10.19517/j.1671-6345.20210344
Abstract:
The frequency band 8025-8400 MHz is extensively used by a large number of sounding data transmission systems of the FY-3 series non-GSO meteorological satellites with earth exploration-satellite service on a primary basis. Many other services and systems operate in the same frequency band. Finding a way to avoid harmful interference and ensure the sharing and compatibility between FY-3 systems and other incumbent systems is significant. At present, the domestic sharing and compatibility studies in this frequency band are not based on the accurate characteristics of the actual meteorological satellites systems, resulting in potential risks of negative effects on the application and delicacy management of the spectrum. Based on the parameters of the data link used by FY-3 satellites, this paper conducts the study and provides the aggregate and single-entry protection criteria and coordination threshold from space and ground directions respectively, which can be directly applied to coordination meetings between FY-3 series and other satellite networks at the national or international level.
The frequency band 8025-8400 MHz is extensively used by a large number of sounding data transmission systems of the FY-3 series non-GSO meteorological satellites with earth exploration-satellite service on a primary basis. Many other services and systems operate in the same frequency band. Finding a way to avoid harmful interference and ensure the sharing and compatibility between FY-3 systems and other incumbent systems is significant. At present, the domestic sharing and compatibility studies in this frequency band are not based on the accurate characteristics of the actual meteorological satellites systems, resulting in potential risks of negative effects on the application and delicacy management of the spectrum. Based on the parameters of the data link used by FY-3 satellites, this paper conducts the study and provides the aggregate and single-entry protection criteria and coordination threshold from space and ground directions respectively, which can be directly applied to coordination meetings between FY-3 series and other satellite networks at the national or international level.
7 Low-frequency Characteristics of Spring Rainfall over Hubei Province and Its Relationship with SST
2022, 50(3):361-368.
DOI: 10.19517/j.1671-6345.20210217
Abstract:
Using the daily precipitation data of 68 stations in Hubei and NCEP/NCAR circulation reanalysis data, the low-frequency characteristics of spring rainfall and its relationship with SST are studied. The results indicate that the quasi-biweekly oscillation of precipitation is obviously in spring over Hubei. Biweekly activity strengthens in the spring flood years while weakens in the spring drought years. The sea surface temperature anomalies (SSTA) of the Indian Ocean and Kuroshio in spring can cause circulation anomaly over the mid-low latitudes and Japan Sea, and then affect the low-frequency activity of spring precipitation in Hubei Province. Under the background of anomaly warmer SSTA of Kuroshio in the 2018 spring, there existed a positive anomaly of 500 hPa height field over the Japan Sea. This anomaly had significant low-frequency oscillation. The southeast flow in the rear part of this anomaly constituted the warm shear with the southwest flow from South China, causing low-frequency rainfall over Hubei. All these resulted in biweekly active abnormality.
Using the daily precipitation data of 68 stations in Hubei and NCEP/NCAR circulation reanalysis data, the low-frequency characteristics of spring rainfall and its relationship with SST are studied. The results indicate that the quasi-biweekly oscillation of precipitation is obviously in spring over Hubei. Biweekly activity strengthens in the spring flood years while weakens in the spring drought years. The sea surface temperature anomalies (SSTA) of the Indian Ocean and Kuroshio in spring can cause circulation anomaly over the mid-low latitudes and Japan Sea, and then affect the low-frequency activity of spring precipitation in Hubei Province. Under the background of anomaly warmer SSTA of Kuroshio in the 2018 spring, there existed a positive anomaly of 500 hPa height field over the Japan Sea. This anomaly had significant low-frequency oscillation. The southeast flow in the rear part of this anomaly constituted the warm shear with the southwest flow from South China, causing low-frequency rainfall over Hubei. All these resulted in biweekly active abnormality.
8 Application of Boundary Wind Profile Radar to Severe Convective Weather Forecast in Central Zhejiang
2022, 50(3):369-379.
DOI: 10.19517/j.1671-6345.20210006
Abstract:
Fifteen severe convective weather cases are analyzed based on Yiwu CFL-03 boundary layer wind profile radar data. The results are as follows: (1) From horizontal wind data the information about cold air mass invasion can be obtained prior to weather synoptic maps. It is helpful to predict severe convective weather and low-level southwest jet, especially ultra low-level southwest jet or southerly jet, which is helpful for short-term rainstorms or hails. The ultra low-level jet is also an indicator of thunderstorm gales. (2) Vertical wind and CN2 are good indicators to reflect the beginning and termination of a rainfall process. For rain events, radial velocity is positive, spectral width broadens in power spectral density diagrams, and the shapes of all signals are similar. (3) Velocity ambiguity in radial velocity maps denotes severe weather processes. Strong wind is happening if velocity ambiguity is at a low level. The wind profiler radar is a reliable instrument to predict the occurrence and development of severe convective weather. The local short-term and nowcasting capability can be effectively strengthened with the Doppler radar data.
Fifteen severe convective weather cases are analyzed based on Yiwu CFL-03 boundary layer wind profile radar data. The results are as follows: (1) From horizontal wind data the information about cold air mass invasion can be obtained prior to weather synoptic maps. It is helpful to predict severe convective weather and low-level southwest jet, especially ultra low-level southwest jet or southerly jet, which is helpful for short-term rainstorms or hails. The ultra low-level jet is also an indicator of thunderstorm gales. (2) Vertical wind and CN2 are good indicators to reflect the beginning and termination of a rainfall process. For rain events, radial velocity is positive, spectral width broadens in power spectral density diagrams, and the shapes of all signals are similar. (3) Velocity ambiguity in radial velocity maps denotes severe weather processes. Strong wind is happening if velocity ambiguity is at a low level. The wind profiler radar is a reliable instrument to predict the occurrence and development of severe convective weather. The local short-term and nowcasting capability can be effectively strengthened with the Doppler radar data.
9 Analysis of a Disastrous Heavy Snow with Freezing Rainfall in 2020 in Southeast of Inner Mongolian
2022, 50(3):380-389.
DOI: 10.19517/j.1671-6345.20210211
Abstract:
Based on routine observational data, NCEP reanalysis data by every 6 hours and daily FY-2G satellite data, a heavy snow with freezing rain happened on 18-19 November 2020 in the southeast of Inner Mongolian is analyzed, including the circulation situation, water vapour condition, dynamic condition and stratification characteristics. The results show that: The atmospheric circulation anomaly was the main atmospheric circulation background of the disastrous weather; The westerly trough at 500 hPa, southwest jet at 700 hPa and northeast jet below 850 hPa, and the cyclone were mainly influencing systems, with the characteristics of a return-flow heavy snow. The water vapour transportation by the southerly and easterly and the moisture convergence provided sufficient water vapour supply, with the maximum specific humidity of 5 g·kg-1 at 850 hPa and 4 g·kg-1 at 700 hPa. The warm air represented by the southerly jet converged with the cold air of the north. The warm and humid air lifted on the low-level “cold pad”, which intensified the development of ascending motions and led to the rapid enhancement of precipitation. The diabatic heating had little effect on the frontogenesis, and the horizontal movement term primarily contributed to frontogenesis. The change of frontogenesis corresponded to the intensity of snow very well, so the front lifting force couldn’t be ignored in the increase of heavy snow; the maintenance of the frontal zone made the low temperature in the low level, and there was temperature inversion on the front. The warm and humid air rised along the front, and the “cold pad” below 900 hPa and “warm cover” above existed for a long time, which led to the occurrence and persistence of heavy snow. The temperature inversion on the front and melting level was conducive to the precipitation phase transformation. The temperature of the middle layer was higher than 0 ℃, and the upper and lower layer temperature was below 0 ℃, which corresponded to the stratification characteristic of melting freezing rain.
Based on routine observational data, NCEP reanalysis data by every 6 hours and daily FY-2G satellite data, a heavy snow with freezing rain happened on 18-19 November 2020 in the southeast of Inner Mongolian is analyzed, including the circulation situation, water vapour condition, dynamic condition and stratification characteristics. The results show that: The atmospheric circulation anomaly was the main atmospheric circulation background of the disastrous weather; The westerly trough at 500 hPa, southwest jet at 700 hPa and northeast jet below 850 hPa, and the cyclone were mainly influencing systems, with the characteristics of a return-flow heavy snow. The water vapour transportation by the southerly and easterly and the moisture convergence provided sufficient water vapour supply, with the maximum specific humidity of 5 g·kg-1 at 850 hPa and 4 g·kg-1 at 700 hPa. The warm air represented by the southerly jet converged with the cold air of the north. The warm and humid air lifted on the low-level “cold pad”, which intensified the development of ascending motions and led to the rapid enhancement of precipitation. The diabatic heating had little effect on the frontogenesis, and the horizontal movement term primarily contributed to frontogenesis. The change of frontogenesis corresponded to the intensity of snow very well, so the front lifting force couldn’t be ignored in the increase of heavy snow; the maintenance of the frontal zone made the low temperature in the low level, and there was temperature inversion on the front. The warm and humid air rised along the front, and the “cold pad” below 900 hPa and “warm cover” above existed for a long time, which led to the occurrence and persistence of heavy snow. The temperature inversion on the front and melting level was conducive to the precipitation phase transformation. The temperature of the middle layer was higher than 0 ℃, and the upper and lower layer temperature was below 0 ℃, which corresponded to the stratification characteristic of melting freezing rain.
2022, 50(3):390-402.
DOI: 10.19517/j.1671-6345.20210362
Abstract:
The characteristics of a supercell hailstorm event, which occurred in the south of Hebei from Laiyuan to Dongguang on June 25, 2020, are analyzed according to the environmental conditions and the wind field retrieval from dual Doppler radar. The results suggest that: (1) This supercell hailstorm was triggered and continuously strengthened in a horizontal convective roll. (2) The possible reasons for the long-life event include that the supercell was in the environment of vertical wind shear, which caused by the medium to strong basic clockwise rotating background wind; the maintenance time of mesocyclone was more than three hours; and there was a strong cold pool. (3) The VIL values of supercells from 55 to 80 kg m-2 lasted for seven hours, which was consistent with the hail path during the period. The three-body scattering spike or sidelobe echo characteristics appeared for more than four hours, which was consistent with the time of large hail confirmed by the meteorological observation and the disaster investigation in the events and had obvious indicative significance for large hail. (4) There were supercell characteristics such as the hook echo at the low levels, echo suspension, dome structure, divergence in the top of the storm, the column of ZDR and KDP, and so on. The reflectivity over the dome was more than 65 dBz. The wind field was mainly vertical upward but weak horizontal component, which formed a structure of cave-channel and zero-region and was conductive to the growth of large hails. The vertical velocity of the supercell increased with height, which was beneficial to the formation and maintenance of mesocyclone.
The characteristics of a supercell hailstorm event, which occurred in the south of Hebei from Laiyuan to Dongguang on June 25, 2020, are analyzed according to the environmental conditions and the wind field retrieval from dual Doppler radar. The results suggest that: (1) This supercell hailstorm was triggered and continuously strengthened in a horizontal convective roll. (2) The possible reasons for the long-life event include that the supercell was in the environment of vertical wind shear, which caused by the medium to strong basic clockwise rotating background wind; the maintenance time of mesocyclone was more than three hours; and there was a strong cold pool. (3) The VIL values of supercells from 55 to 80 kg m-2 lasted for seven hours, which was consistent with the hail path during the period. The three-body scattering spike or sidelobe echo characteristics appeared for more than four hours, which was consistent with the time of large hail confirmed by the meteorological observation and the disaster investigation in the events and had obvious indicative significance for large hail. (4) There were supercell characteristics such as the hook echo at the low levels, echo suspension, dome structure, divergence in the top of the storm, the column of ZDR and KDP, and so on. The reflectivity over the dome was more than 65 dBz. The wind field was mainly vertical upward but weak horizontal component, which formed a structure of cave-channel and zero-region and was conductive to the growth of large hails. The vertical velocity of the supercell increased with height, which was beneficial to the formation and maintenance of mesocyclone.
2022, 50(3):403-411.
DOI: 10.19517/j.1671-6345.20210272
Abstract:
Aiming at the natural icing flight test of a helicopter, combined with the helicopter’s flight characteristics, the determining principle of the test flight route under different meteorological conditions is analyzed. The CMA Weather Modification Centre designed the helicopter icing test flight scheme based on the cloud structure conditions of the model forecast and real-time monitoring, applied, and verified it in the field test in Urumqi, Xinjiang, in March 2018. The results show that the determination principle of the natural helicopter icing test flight scheme mainly considers the meteorological conditions of cloud icing, cloud macro and micro characteristics, helicopter characteristics, etc. According to the position of the icing area relative to the cloud area, the principle of entering the icing area from the cloud bottom or cloud top is considered. The design process of the aircraft icing flight scheme is established. The ice potential prediction system is used to carry out probability prediction 72 hours in advance. The cloud precipitation explicit prediction system is used to carry out cloud condition prediction 24 hours in advance. The satellite inversion products carry out ice accretion condition monitoring and early warning 3 hours in advance. The forecast and monitoring results show that the macro and micro conditions of clouds in the planned test are ideal, in line with the conditions for the formation of aircraft icing. In view of this cloud, we design a way to avoid the cloud bottom entering into the detection area and exiting from the cloud bottom. To complete the ice detection, we use multiple climbing and flying to find the supercooled water area in the cloud. In the actual flight, ice accretion and supercooled water are also detected in the cloud, which is an ideal design and application example of aircraft icing.
Aiming at the natural icing flight test of a helicopter, combined with the helicopter’s flight characteristics, the determining principle of the test flight route under different meteorological conditions is analyzed. The CMA Weather Modification Centre designed the helicopter icing test flight scheme based on the cloud structure conditions of the model forecast and real-time monitoring, applied, and verified it in the field test in Urumqi, Xinjiang, in March 2018. The results show that the determination principle of the natural helicopter icing test flight scheme mainly considers the meteorological conditions of cloud icing, cloud macro and micro characteristics, helicopter characteristics, etc. According to the position of the icing area relative to the cloud area, the principle of entering the icing area from the cloud bottom or cloud top is considered. The design process of the aircraft icing flight scheme is established. The ice potential prediction system is used to carry out probability prediction 72 hours in advance. The cloud precipitation explicit prediction system is used to carry out cloud condition prediction 24 hours in advance. The satellite inversion products carry out ice accretion condition monitoring and early warning 3 hours in advance. The forecast and monitoring results show that the macro and micro conditions of clouds in the planned test are ideal, in line with the conditions for the formation of aircraft icing. In view of this cloud, we design a way to avoid the cloud bottom entering into the detection area and exiting from the cloud bottom. To complete the ice detection, we use multiple climbing and flying to find the supercooled water area in the cloud. In the actual flight, ice accretion and supercooled water are also detected in the cloud, which is an ideal design and application example of aircraft icing.
2022, 50(3):412-419.
DOI: 10.19517/j.1671-6345.20210225
Abstract:
Using ERA-interim reanalysis data and aircraft air reports in south-central China, the application effects of seven indexes in air turbulence are compared and analyzed. The results show that the Brown index has the lowest coincidence rate between different indexes with or without turbulence, followed by the ellrod1 and ellrod2. The strength and existence of turbulence can be judged from the index values, and the false alarm rate is low; The coincidence rate of MOS-CAT and L-P index range is too high, which is easy to cause high false alarm. The turbulence areas calculated by the ellrod1, ellrod2 and Brown correspond best to the positions reported in the air. Dutton and HTG are unstable; the calculation ranges of MOS-CAT and L-P index are too large, and the applicability is poor. The calculation emphases of different indexes are different. When thermal factors are dominant, the calculation effect of HTG index is better.
Using ERA-interim reanalysis data and aircraft air reports in south-central China, the application effects of seven indexes in air turbulence are compared and analyzed. The results show that the Brown index has the lowest coincidence rate between different indexes with or without turbulence, followed by the ellrod1 and ellrod2. The strength and existence of turbulence can be judged from the index values, and the false alarm rate is low; The coincidence rate of MOS-CAT and L-P index range is too high, which is easy to cause high false alarm. The turbulence areas calculated by the ellrod1, ellrod2 and Brown correspond best to the positions reported in the air. Dutton and HTG are unstable; the calculation ranges of MOS-CAT and L-P index are too large, and the applicability is poor. The calculation emphases of different indexes are different. When thermal factors are dominant, the calculation effect of HTG index is better.
2022, 50(3):420-427.
DOI: 10.19517/j.1671-6345.20210287
Abstract:
Based on the daily inbound and outbound flow and output data of Xiluodu Hydropower Station, the daily electricity load data of Guangdong, and the daily re-analysis data of NCEP from 2015 to 2017, this paper divides the production scenarios of Xiluodu Right Bank Hydropower Station into three types: short supply, oversupply and atypical oversupply. They are characterized by insufficient water in the dry season, severe water abandonment in flood season, and contradiction between power generation and power demand of Guangdong Province. Typical cases are selected to analyze the circulation situation and weather causes corresponding to different types, and suggestions for future dispatching of Xiluodu Hydropower Station are put forward. The results show that in May and June of each year, Guangdong is often controlled by subtropical high pressure, and the demand for electricity increases significantly. The drainage area above Yinbin is mainly located on the northwest side of the anticyclonic circulation and is controlled by a uniform westward or southwestern warm and humid air. There is no cold air activity, which is not conducive to large-scale precipitation. As a result, the power generation capacity of Xiluodu Hydropower Station is insufficient and the demand for electricity in Guangdong exceeds supply. The drainage area above Yinbin is mostly affected by plateau troughs and shear lines or cold air from the east from July to September, conducive to significant precipitation. During this period, the power station has full capacity. However, when Guangdong is affected by the typhoon system or is located on the north side of the subtropical high pressure, the power demand in Guangdong decreases, resulting in an over-supply type. If Guangdong is under the control of subtropical high voltage, the electricity demand is high. However, water abandonment on the right bank of Xiluodu happens frequently due to the increased output of other hydropower stations in the southwestern region and limited power transmission, which has led to a decreased demand for power from the power grid on the right bank of Xiluodu. This situation corresponds to atypical oversupply. In actual power generation productions, it is possible to study and judge in advance according to weather circulation situation and better carry out reservoir dispatching, optimize power station operation, and increase the effective consumption of hydroelectric power and full utilization of hydropower resources during flood periods.
Based on the daily inbound and outbound flow and output data of Xiluodu Hydropower Station, the daily electricity load data of Guangdong, and the daily re-analysis data of NCEP from 2015 to 2017, this paper divides the production scenarios of Xiluodu Right Bank Hydropower Station into three types: short supply, oversupply and atypical oversupply. They are characterized by insufficient water in the dry season, severe water abandonment in flood season, and contradiction between power generation and power demand of Guangdong Province. Typical cases are selected to analyze the circulation situation and weather causes corresponding to different types, and suggestions for future dispatching of Xiluodu Hydropower Station are put forward. The results show that in May and June of each year, Guangdong is often controlled by subtropical high pressure, and the demand for electricity increases significantly. The drainage area above Yinbin is mainly located on the northwest side of the anticyclonic circulation and is controlled by a uniform westward or southwestern warm and humid air. There is no cold air activity, which is not conducive to large-scale precipitation. As a result, the power generation capacity of Xiluodu Hydropower Station is insufficient and the demand for electricity in Guangdong exceeds supply. The drainage area above Yinbin is mostly affected by plateau troughs and shear lines or cold air from the east from July to September, conducive to significant precipitation. During this period, the power station has full capacity. However, when Guangdong is affected by the typhoon system or is located on the north side of the subtropical high pressure, the power demand in Guangdong decreases, resulting in an over-supply type. If Guangdong is under the control of subtropical high voltage, the electricity demand is high. However, water abandonment on the right bank of Xiluodu happens frequently due to the increased output of other hydropower stations in the southwestern region and limited power transmission, which has led to a decreased demand for power from the power grid on the right bank of Xiluodu. This situation corresponds to atypical oversupply. In actual power generation productions, it is possible to study and judge in advance according to weather circulation situation and better carry out reservoir dispatching, optimize power station operation, and increase the effective consumption of hydroelectric power and full utilization of hydropower resources during flood periods.
2022, 50(3):428-437.
DOI: 10.19517/j.1671-6345.20210306
Abstract:
Taking the urban development strategic planning of Zibo city (2017-2030) as an example, this paper analyses the climate suitability assessment of the urban industrial layout based on multivariate data analysis. The wind environment, thermal environment and atmospheric environment, closely related to urban planning, are comprehensively analysed using meteorological, remote sensing and environmental data. The results show that there is a certain spatial difference in the dominant wind direction and wind speed within the planning area. The dominant wind path in Huantai and Linzi, located in the northern part of Zibo, is mostly east-west, and the rest of the area is mainly south-north. The eastern area of Linzi and the central area of Zichuan are regions with high annual wind speeds, while most of Zhoucun, Zhangdian and the southern area of Boshan are regions with small wind speeds. The extent of the urban heat island has expanded significantly over time, with the twoaxis area as the core, showing a sprawling development. The area of the relatively strong and stronger heat island in the planning area has grown from 405 km2 in 2009 to 918 km2 in 2016, among which Zhangdian displays the fastest growth rate. The results of the sensitivity simulation experiment show that pollution convergence zones are likely to occur in front of the mountain, and the area with a high concentration of PM2.5 is mainly distributed in the north-central plains of Zibo. The pollution diffusion condition in the northern and eastern regions of the city is relatively good. The diffusion characteristics of air pollutants emitted by industries in various regions are mainly affected by the dominant winds in different areas. Among them, the diffusion of pollutants in the north of Zichuan and the south of Zhangdian is easy to have a greater impact on the entire central city. Comprehensively considering the above analysis results of wind environment, thermal environment, and atmospheric environment, the classification of the sensitive areas of atmospheric environment in the planning area is carried out, and the suitability of the industrial layout for five types of areas is clarified. From the perspective of improving the local climate and atmospheric environment, this paper put forward planning suggestions that provide scientific support for rational allocation of land functions and industrial layout optimisation.
Taking the urban development strategic planning of Zibo city (2017-2030) as an example, this paper analyses the climate suitability assessment of the urban industrial layout based on multivariate data analysis. The wind environment, thermal environment and atmospheric environment, closely related to urban planning, are comprehensively analysed using meteorological, remote sensing and environmental data. The results show that there is a certain spatial difference in the dominant wind direction and wind speed within the planning area. The dominant wind path in Huantai and Linzi, located in the northern part of Zibo, is mostly east-west, and the rest of the area is mainly south-north. The eastern area of Linzi and the central area of Zichuan are regions with high annual wind speeds, while most of Zhoucun, Zhangdian and the southern area of Boshan are regions with small wind speeds. The extent of the urban heat island has expanded significantly over time, with the twoaxis area as the core, showing a sprawling development. The area of the relatively strong and stronger heat island in the planning area has grown from 405 km2 in 2009 to 918 km2 in 2016, among which Zhangdian displays the fastest growth rate. The results of the sensitivity simulation experiment show that pollution convergence zones are likely to occur in front of the mountain, and the area with a high concentration of PM2.5 is mainly distributed in the north-central plains of Zibo. The pollution diffusion condition in the northern and eastern regions of the city is relatively good. The diffusion characteristics of air pollutants emitted by industries in various regions are mainly affected by the dominant winds in different areas. Among them, the diffusion of pollutants in the north of Zichuan and the south of Zhangdian is easy to have a greater impact on the entire central city. Comprehensively considering the above analysis results of wind environment, thermal environment, and atmospheric environment, the classification of the sensitive areas of atmospheric environment in the planning area is carried out, and the suitability of the industrial layout for five types of areas is clarified. From the perspective of improving the local climate and atmospheric environment, this paper put forward planning suggestions that provide scientific support for rational allocation of land functions and industrial layout optimisation.
2022, 50(3):438-448.
DOI: 10.19517/j.1671-6345.20210145
Abstract:
In the dawn of the mobile computing era, it has witnessed an exciting leap in information technologies such as artificial intelligence, big data mining, and GPU parallel computing, as well as the unification of Web standards. This progress facilitates the birth and development of a great number of meteorological data visualization applications targeting mobile computing platforms. However, thanks to underpowered computational capability and incomplete features of the graphics toolkit in mobile devices, most domestic Web applications lack innovative visualization methods, and have poor browser compatibility and performance. To deal with these problems, a B/S meteorological data interactive analysis and display Web application named WeatherApp has been developed. Two innovations are proposed. First, a unified two- and three-dimensional digital Earth engine is constructed. It not only provides commonly-used geographical information system features but also is capable of quick switching between views of different dimensions. Next, a number of advanced three-dimensional visualization methods, including vector field flowlines and volume rendering, are developed. The proposed application has been applied in typhoon forecast operations, and encouraging results are obtained. By supporting all mainstream Web browsers built for both desktop and mobile platforms, WeatherApp provides a convenient way for users to view data of interest anywhere and anytime, greatly enhancing users’ productivity.
In the dawn of the mobile computing era, it has witnessed an exciting leap in information technologies such as artificial intelligence, big data mining, and GPU parallel computing, as well as the unification of Web standards. This progress facilitates the birth and development of a great number of meteorological data visualization applications targeting mobile computing platforms. However, thanks to underpowered computational capability and incomplete features of the graphics toolkit in mobile devices, most domestic Web applications lack innovative visualization methods, and have poor browser compatibility and performance. To deal with these problems, a B/S meteorological data interactive analysis and display Web application named WeatherApp has been developed. Two innovations are proposed. First, a unified two- and three-dimensional digital Earth engine is constructed. It not only provides commonly-used geographical information system features but also is capable of quick switching between views of different dimensions. Next, a number of advanced three-dimensional visualization methods, including vector field flowlines and volume rendering, are developed. The proposed application has been applied in typhoon forecast operations, and encouraging results are obtained. By supporting all mainstream Web browsers built for both desktop and mobile platforms, WeatherApp provides a convenient way for users to view data of interest anywhere and anytime, greatly enhancing users’ productivity.
2022, 50(3):449-458.
DOI: 10.19517/j.1671-6345.20210308
Abstract:
The paper introduces the threedimensional (3D) visualization for weather radar base data through 3D interpolation and VTK (Visualization Toolkit) based on the Weather Radar Base Data Structure Analysis Software developed by the authors, which is in favour of various operating systems.The 3D reconstruction supports several interactive operating systems and rapidly highlights the structural features of radar echo, such as allowing the 3D reconstruction in any rectangular region on radar plan, supporting the superposition of terrain and radar echo, having the functions of zoom, roam and viewpoint change, providing the adjustment of transparency and illumination coefficient of different intensity intervals and getting the section view and 3D view of different kinds. Finally, the paper shows how the 3D reconstruction helps forecasters rapidly grasp storm structures and their evolution rules according to the situations, including the severe convection cell and typhoon where this software applies.
The paper introduces the threedimensional (3D) visualization for weather radar base data through 3D interpolation and VTK (Visualization Toolkit) based on the Weather Radar Base Data Structure Analysis Software developed by the authors, which is in favour of various operating systems.The 3D reconstruction supports several interactive operating systems and rapidly highlights the structural features of radar echo, such as allowing the 3D reconstruction in any rectangular region on radar plan, supporting the superposition of terrain and radar echo, having the functions of zoom, roam and viewpoint change, providing the adjustment of transparency and illumination coefficient of different intensity intervals and getting the section view and 3D view of different kinds. Finally, the paper shows how the 3D reconstruction helps forecasters rapidly grasp storm structures and their evolution rules according to the situations, including the severe convection cell and typhoon where this software applies.
2022, 50(3):459-466.
DOI: 10.19517/j.1671-6345.20210081
Abstract:
The meteorological SMS (Short Message Service) has a history of more than ten years in the meteorological department. It has a wide coverage. The message can provide 70 words of text service at most because it is limited by the technical capability of the traditional SMS gateway. In 2020, as the three major operators jointly released the “5G News (5GMC) White Paper”, RCS (Rich media communications) was launched. The technology can integrate voice, message, video, community network and other functions, providing technical support for the overall upgrading of traditional short message business. Based on the RCS UP1.0 standards generally supported by mobile terminals, a “5G weather compass produce and release support system” is studied and established to provide multimedia weather messages in pictures, videos and so on. The system can also enable non-5G users to achieve 5G messages by means of MMS (Multimedia Messaging Service) pullback through the Chatbot NFS (Network File System) fall technology. It iteratively updates traditional weather messages and obtains good operation effects.
The meteorological SMS (Short Message Service) has a history of more than ten years in the meteorological department. It has a wide coverage. The message can provide 70 words of text service at most because it is limited by the technical capability of the traditional SMS gateway. In 2020, as the three major operators jointly released the “5G News (5GMC) White Paper”, RCS (Rich media communications) was launched. The technology can integrate voice, message, video, community network and other functions, providing technical support for the overall upgrading of traditional short message business. Based on the RCS UP1.0 standards generally supported by mobile terminals, a “5G weather compass produce and release support system” is studied and established to provide multimedia weather messages in pictures, videos and so on. The system can also enable non-5G users to achieve 5G messages by means of MMS (Multimedia Messaging Service) pullback through the Chatbot NFS (Network File System) fall technology. It iteratively updates traditional weather messages and obtains good operation effects.
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.