Volume 46,Issue 3,2018 Table of Contents
2018, 46(3):429-435.
Abstract:
The quality of the rotary joints greatly influences the consistency of the dual channel of polarimetric radar. Actually, the bias of 〖WTBX〗Z〖WTBZ〗dr varies with azimuth and elevation because the rotary joints are asymmetric in structure due to the production process, and it affects the accuracy of using radar data for quantitative precipitation estimation and hydrometeor classification. The CW (Continuous Wave) signals of the Cband dualpolarization radar of the Nanjing University of Information Science and Technology were used to detect the measurement errors caused by the rotary joint for azimuth and elevation. The results show that the rotary joints have some influence on the measurement results of 〖WTBX〗Z〖WTBZ〗dr of dual polarization weather radar, and it can be seen that the effect is relatively stable, in combined with the results of VCP and RHI, which provides a basis for the correction of the errors caused by rotary joints in using radar data.
The quality of the rotary joints greatly influences the consistency of the dual channel of polarimetric radar. Actually, the bias of 〖WTBX〗Z〖WTBZ〗dr varies with azimuth and elevation because the rotary joints are asymmetric in structure due to the production process, and it affects the accuracy of using radar data for quantitative precipitation estimation and hydrometeor classification. The CW (Continuous Wave) signals of the Cband dualpolarization radar of the Nanjing University of Information Science and Technology were used to detect the measurement errors caused by the rotary joint for azimuth and elevation. The results show that the rotary joints have some influence on the measurement results of 〖WTBX〗Z〖WTBZ〗dr of dual polarization weather radar, and it can be seen that the effect is relatively stable, in combined with the results of VCP and RHI, which provides a basis for the correction of the errors caused by rotary joints in using radar data.
2018, 46(3):436-442.
Abstract:
The unstable operation of the CINRAD/SA radar servo system is analyzed, and abnormal radar echoes, which are mainly caused by servo faults, the overrunning and jumping of positioning of radar azimuth pitch, are divided into three categories. We study the quality control method of the overrunning, jumping, and faults of azimuth pitch positioning of the radar servo system from the radar base data, which can timely detect the abnormal echoes problems of radar, release the warning message, guide the maintenance in time, control the generation of abnormal echo data induced by the radar servo system from the sources, and improve the radar data and product quality.
The unstable operation of the CINRAD/SA radar servo system is analyzed, and abnormal radar echoes, which are mainly caused by servo faults, the overrunning and jumping of positioning of radar azimuth pitch, are divided into three categories. We study the quality control method of the overrunning, jumping, and faults of azimuth pitch positioning of the radar servo system from the radar base data, which can timely detect the abnormal echoes problems of radar, release the warning message, guide the maintenance in time, control the generation of abnormal echo data induced by the radar servo system from the sources, and improve the radar data and product quality.
2018, 46(3):443-449.
Abstract:
The trigger amplifier of a radar transmitter provides a discharge trigger for Silicon Controlled Rectifiers (SCRs) and protects itself from being damaged. The diagnosis procedures of the trigger amplifier is described, which locates faults to the chip level of the unit and lowers the expenses of hardware maintenance, and provides the technical support in the autodiagnostic model on the radar test platform. The standardized diagnosis procedures of the trigger amplifier are based on the trigger signal flow, the measurements of pulse waves and voltages of the key points, as well as the causal relationship of the fault tree diagram. An example is given, in which minus 200 voltages did not appear because of the lack of trigger output. The results show that the procedures are useful for finding the fault chips in the trigger amplifier, easy to learn for the radar technique personnel, and effective for improving the availability ratio of the radar system.
The trigger amplifier of a radar transmitter provides a discharge trigger for Silicon Controlled Rectifiers (SCRs) and protects itself from being damaged. The diagnosis procedures of the trigger amplifier is described, which locates faults to the chip level of the unit and lowers the expenses of hardware maintenance, and provides the technical support in the autodiagnostic model on the radar test platform. The standardized diagnosis procedures of the trigger amplifier are based on the trigger signal flow, the measurements of pulse waves and voltages of the key points, as well as the causal relationship of the fault tree diagram. An example is given, in which minus 200 voltages did not appear because of the lack of trigger output. The results show that the procedures are useful for finding the fault chips in the trigger amplifier, easy to learn for the radar technique personnel, and effective for improving the availability ratio of the radar system.
2018, 46(3):450-454.
Abstract:
The azimuth and elevation calibration of Lband radar are usually conducted by Polaris and theodolites; however, there is lack of reliable and effective tools to test its correctness.This paper adopts the solar position algorithm with a high degree of accuracy, uses the Python language program to design and package. According to the actual latitude and longitude, solar declination angle, and the time difference of the station, the sun position is calculated in real time to calibrate the radar antenna pointing in theory. The test and tolerance analysis are carried out in several stations, and the accuracy is within 03 degrees，referring to the domestic new generation weather radar antenna beam pointing calibration specifications (≤03 degrees). The accuracy meets the operation requirements.At the same time, the algorithm software can also provide a more efficient way to check the daily radar performance and check whether there are troubles in radar, so to ensure the reliability of sounding data.
The azimuth and elevation calibration of Lband radar are usually conducted by Polaris and theodolites; however, there is lack of reliable and effective tools to test its correctness.This paper adopts the solar position algorithm with a high degree of accuracy, uses the Python language program to design and package. According to the actual latitude and longitude, solar declination angle, and the time difference of the station, the sun position is calculated in real time to calibrate the radar antenna pointing in theory. The test and tolerance analysis are carried out in several stations, and the accuracy is within 03 degrees，referring to the domestic new generation weather radar antenna beam pointing calibration specifications (≤03 degrees). The accuracy meets the operation requirements.At the same time, the algorithm software can also provide a more efficient way to check the daily radar performance and check whether there are troubles in radar, so to ensure the reliability of sounding data.
2018, 46(3):455-461.
Abstract:
Products of CINRDA/SA are generated by radar base data directly or algorithms based on base data indirectly. Sometimes data quality goes wrong. Combing the running status information with radar base data to conduct the quality control of weather radar data is an effective approach, which can find the problems such as the abnormal values of radar echoes, no echo, and bad radar charts in time. In order to construct the stationlevel quality control method of weather radar data, the performance parameters and the monitoring and alarm information of nine weather radar sets in Jiangsu Province are analyzed, and the samples of abnormal echoes and base data are statistically analyzed and studied in detail. Based on above, the stationlevel quality control method is built, aiming to monitor the radar base data. The testing of radar base data quality is carried out. The alarm message can be sent to the duty officer immediately when it goes wrong, which is done to prevent abnormal echo data from entering the field of prediction. The prediction accuracy can be improved indirectly.
Products of CINRDA/SA are generated by radar base data directly or algorithms based on base data indirectly. Sometimes data quality goes wrong. Combing the running status information with radar base data to conduct the quality control of weather radar data is an effective approach, which can find the problems such as the abnormal values of radar echoes, no echo, and bad radar charts in time. In order to construct the stationlevel quality control method of weather radar data, the performance parameters and the monitoring and alarm information of nine weather radar sets in Jiangsu Province are analyzed, and the samples of abnormal echoes and base data are statistically analyzed and studied in detail. Based on above, the stationlevel quality control method is built, aiming to monitor the radar base data. The testing of radar base data quality is carried out. The alarm message can be sent to the duty officer immediately when it goes wrong, which is done to prevent abnormal echo data from entering the field of prediction. The prediction accuracy can be improved indirectly.
2018, 46(3):462-467.
Abstract:
Based on the Lband secondbysecond radiosonde data, a second by second quality control method is developed. A series of quality control measures were devised to deal with various issues after observation, such checks as on large segment data missing, instantaneous value, cast point, balloon cast time, height difference, temperature variability, air pressure variability, relative humidity variability, elevation angle variability, horizontal angle variability check, slant range variability, rising speed, end point, and constant value. According to the quality control results of the second by second radiosonde data over Sichuan in 2016, the quality control method performed well. The quality control results show that the number of observations passing the height difference check is only 1105 The number of observations passing the slant range variability check is 2221 The passing rate of horizontal angle variability check, temperature variability check, and elevation angle variability check are 60% to 70%. The passing rates of cast point check, balloon cast time check, relative humidity variability check are close to 90%. The passing rates of other checks are more than 90%. Generally, in the second by second radiosonde data, the frequency of abnormal slant range data is relatively higher, and the cases in excess of the threshold of the height difference calculated by radar and the pressureheight formula are more frequent. The suspicious messages by other checks are less.
Based on the Lband secondbysecond radiosonde data, a second by second quality control method is developed. A series of quality control measures were devised to deal with various issues after observation, such checks as on large segment data missing, instantaneous value, cast point, balloon cast time, height difference, temperature variability, air pressure variability, relative humidity variability, elevation angle variability, horizontal angle variability check, slant range variability, rising speed, end point, and constant value. According to the quality control results of the second by second radiosonde data over Sichuan in 2016, the quality control method performed well. The quality control results show that the number of observations passing the height difference check is only 1105 The number of observations passing the slant range variability check is 2221 The passing rate of horizontal angle variability check, temperature variability check, and elevation angle variability check are 60% to 70%. The passing rates of cast point check, balloon cast time check, relative humidity variability check are close to 90%. The passing rates of other checks are more than 90%. Generally, in the second by second radiosonde data, the frequency of abnormal slant range data is relatively higher, and the cases in excess of the threshold of the height difference calculated by radar and the pressureheight formula are more frequent. The suspicious messages by other checks are less.
2018, 46(3):468-473.
Abstract:
Meteorological radiation observation data is the foundation of meteorological operations, service and scientific researches, so its quality control is very important. By analyzing the problems from the surface meteorological radiation observation records of Gansu Province in recent years, according to the surface meteorological observation specification requirements and actual work experiences, this paper summarizes the quality control methods of meteorological radiation observation records and abnormal values, aiming to provide a reference for stations in improving the quality of the monthly radiation data file and provide some useful help for the provincial meteorological data quality control, especially for the new staff. The results show that when the instrument is normal, abnormal records need to be judged manually in combination with the meteorological elements at that time, which is the most effective way of meteorological radiation data quality control at the present stage. When the instrument fails, the abnormal records should be considered according to different situations; for example, abnormal values and missing values should be replaced in accordance with the relevant operation regulations. For the problems prone to errors in the records, the observers and quality control personnel are required to improve professional skills, summarize work experiences, and avoid similar problems.
Meteorological radiation observation data is the foundation of meteorological operations, service and scientific researches, so its quality control is very important. By analyzing the problems from the surface meteorological radiation observation records of Gansu Province in recent years, according to the surface meteorological observation specification requirements and actual work experiences, this paper summarizes the quality control methods of meteorological radiation observation records and abnormal values, aiming to provide a reference for stations in improving the quality of the monthly radiation data file and provide some useful help for the provincial meteorological data quality control, especially for the new staff. The results show that when the instrument is normal, abnormal records need to be judged manually in combination with the meteorological elements at that time, which is the most effective way of meteorological radiation data quality control at the present stage. When the instrument fails, the abnormal records should be considered according to different situations; for example, abnormal values and missing values should be replaced in accordance with the relevant operation regulations. For the problems prone to errors in the records, the observers and quality control personnel are required to improve professional skills, summarize work experiences, and avoid similar problems.
Jiang Yi
,
Wang Lijun
,
Yang Qingwen
,
Wang Xiaoguang
,
Chen Haili
,
Chen Zhenli
,
Yan Jingmin
,
Shi Chenxiao
2018, 46(3):474-478.
Abstract:
The South China Sea is an important part of China’s territory, and it has a great strategic significance for China. In order to ensure the reliability and availability of the data from the island weather stations, this paper analyzes the error messages that are generated by the original quality control system, and in order to reduce the number of false checks for the regional automatic stations on the South China Sea, a method is developed, which can check the data difference between two stations on the same island, and the spatial consistency check method is improved. By using the new method to check the data of the regional automatic stations on the South China Sea from September 2015 to July 2016, the removed false check messages accounts for 717% of the original false check messages. The accuracy of error detection is greatly improved.
The South China Sea is an important part of China’s territory, and it has a great strategic significance for China. In order to ensure the reliability and availability of the data from the island weather stations, this paper analyzes the error messages that are generated by the original quality control system, and in order to reduce the number of false checks for the regional automatic stations on the South China Sea, a method is developed, which can check the data difference between two stations on the same island, and the spatial consistency check method is improved. By using the new method to check the data of the regional automatic stations on the South China Sea from September 2015 to July 2016, the removed false check messages accounts for 717% of the original false check messages. The accuracy of error detection is greatly improved.
2018, 46(3):479-484.
Abstract:
Several experiments were made by means of the micro multirotor UAV (Unmanned Aerial Vehicle) carrying device to conduct air temperature and relative humidity observation. The results show: (1) the observing data transmission stability is better when using the 433MHZ wireless transmission; (2) the temperature and relative humidity sensors pass the metrological verification; (3) the air temperature and relative humidity consistency between this device and the shelter in the National Automatic Weather Station is better; (4) during the hovering, the observation error is less and the correlation is good between two devices; (5) when using the device and a radiosonde at the same time, the mean absolute error of is 084 ℃ for air temperature and 4% for relative humidity, and there appeared smallamplitude changes in temperature and relative humidity, which can attribute to the response time, ventilation and radiation protector, flying speed, etc.
Several experiments were made by means of the micro multirotor UAV (Unmanned Aerial Vehicle) carrying device to conduct air temperature and relative humidity observation. The results show: (1) the observing data transmission stability is better when using the 433MHZ wireless transmission; (2) the temperature and relative humidity sensors pass the metrological verification; (3) the air temperature and relative humidity consistency between this device and the shelter in the National Automatic Weather Station is better; (4) during the hovering, the observation error is less and the correlation is good between two devices; (5) when using the device and a radiosonde at the same time, the mean absolute error of is 084 ℃ for air temperature and 4% for relative humidity, and there appeared smallamplitude changes in temperature and relative humidity, which can attribute to the response time, ventilation and radiation protector, flying speed, etc.
2018, 46(3):485-489.
Abstract:
The retrieval accuracy of Gband Vapor Radiometer (GVR) in Tianjin is examined through numerical simulation by using Beijing radiosonde data, which are divided into four seasons, in order to study the applicability of GVR with its own retrival algorithm in Tianjin. The results show that the accumulated liquid water retrival precision has no significant change with height. The relative deviation ranges of the accumulated liquid water in four seasons are 29% to 78%, 31% to 71%, 36% to 67%, 35% to 79% while the absolute deviation ranges are 004 to 0492 mm, 0075 to 0294 mm, 0074 to 0315 mm, 0116 to 0347 mm, respectively. The accumulated water vapor retrival precision decreases significantly in all the seasons, especially under the height of 3 km. The relative deviation range below 3 km of the accumulated water vapor in four seasons are 26% to 208%, 79% to 191%, 43% to 165%, 34% to 142%, while above 3 km are 64% to 897%, 125% to 369%, 132% to 50%, 118% to 301%. Compared with the other types of airborne microwave radiometers and ground GVRs used in the Arctic, the retrieval precision of the accumulated liquid water and water vapor in Tianjin is lower obviously.
The retrieval accuracy of Gband Vapor Radiometer (GVR) in Tianjin is examined through numerical simulation by using Beijing radiosonde data, which are divided into four seasons, in order to study the applicability of GVR with its own retrival algorithm in Tianjin. The results show that the accumulated liquid water retrival precision has no significant change with height. The relative deviation ranges of the accumulated liquid water in four seasons are 29% to 78%, 31% to 71%, 36% to 67%, 35% to 79% while the absolute deviation ranges are 004 to 0492 mm, 0075 to 0294 mm, 0074 to 0315 mm, 0116 to 0347 mm, respectively. The accumulated water vapor retrival precision decreases significantly in all the seasons, especially under the height of 3 km. The relative deviation range below 3 km of the accumulated water vapor in four seasons are 26% to 208%, 79% to 191%, 43% to 165%, 34% to 142%, while above 3 km are 64% to 897%, 125% to 369%, 132% to 50%, 118% to 301%. Compared with the other types of airborne microwave radiometers and ground GVRs used in the Arctic, the retrieval precision of the accumulated liquid water and water vapor in Tianjin is lower obviously.
11 Monitoring and Early Warning of ShortTime Strong Rainfall and Its Application to Mountain Areas
2018, 46(3):490-496.
Abstract:
In order to improve the monitoring and early warning technology of shorttime strong rainfall and its application to mountain areas, selecting the relevant radiosonde data, identifying the type of precipitation, and combined with the automatic correction technology, the classification optimization technique of 〖WTBX〗ZI〖WTBZ〗 relationship is used to estimating rainfall. Besides, the radar reflectivity factor is extrapolated by using the crosscorrelation extrapolation method, and the cumulative precipitation in 30 minutes is predicted. Based on the observation data of nearly three years, the grades of precipitation corresponding to the radar reflection and radar rainfall estimate at Yueyang are determined. Compared with the data of automatic stations, the relative error of the precipitation estimate is smaller; compared with the empirical formula of 〖WTBX〗ZI〖WTBZ〗 relationship, the accuracy of the rainfall estimate by the classification optimization technology of 〖WTBX〗ZI〖WTBZ〗 relationship shows improvement. After a year of application in Yueyang Meteorological Service, the early warning technology has a good result in the precipitation estimation and shorttime strong rainfall warning.
In order to improve the monitoring and early warning technology of shorttime strong rainfall and its application to mountain areas, selecting the relevant radiosonde data, identifying the type of precipitation, and combined with the automatic correction technology, the classification optimization technique of 〖WTBX〗ZI〖WTBZ〗 relationship is used to estimating rainfall. Besides, the radar reflectivity factor is extrapolated by using the crosscorrelation extrapolation method, and the cumulative precipitation in 30 minutes is predicted. Based on the observation data of nearly three years, the grades of precipitation corresponding to the radar reflection and radar rainfall estimate at Yueyang are determined. Compared with the data of automatic stations, the relative error of the precipitation estimate is smaller; compared with the empirical formula of 〖WTBX〗ZI〖WTBZ〗 relationship, the accuracy of the rainfall estimate by the classification optimization technology of 〖WTBX〗ZI〖WTBZ〗 relationship shows improvement. After a year of application in Yueyang Meteorological Service, the early warning technology has a good result in the precipitation estimation and shorttime strong rainfall warning.
2018, 46(3):497-502.
Abstract:
The WMO Information System (WIS) provides information collection and sharing, and discovery access retrieval (DAR) services to support all WMO and related international programs, which requires WIS having high availability and efficiency as operational indices. In order to keep availability and efficiency, it is necessary to implement WIS monitoring. The WIS monitoring portal implements the monitoring of WIS centers based on the agreed monitoring JSON specification, including service status, metrics and statistics, which fully covers the requirements of WIS monitoring. The implementation of the WIS monitoring portal site is based on the open source enterprise application framework and nonrelational database management system. It demonstrates in real time WIS monitoring information to public on Internet, reflecting WIS services problems, which provides an efficient mean for improving the quality and competence of WIS services.
The WMO Information System (WIS) provides information collection and sharing, and discovery access retrieval (DAR) services to support all WMO and related international programs, which requires WIS having high availability and efficiency as operational indices. In order to keep availability and efficiency, it is necessary to implement WIS monitoring. The WIS monitoring portal implements the monitoring of WIS centers based on the agreed monitoring JSON specification, including service status, metrics and statistics, which fully covers the requirements of WIS monitoring. The implementation of the WIS monitoring portal site is based on the open source enterprise application framework and nonrelational database management system. It demonstrates in real time WIS monitoring information to public on Internet, reflecting WIS services problems, which provides an efficient mean for improving the quality and competence of WIS services.
2018, 46(3):503-508.
Abstract:
The integrated surface meteorological data processing system is an operational system based on the provincenation unified CIMISS data environment, which can produce in quasireal time the daily, 5day, 10day, monthly, and annual products and meet the needs of the ground meteorological data users after quality control. This paper introduces the development of the integrated realtime meteorological data processing system from the aspects of software requirement analysis, statistical method, function realization, and key technology. By running the strategy configuration, the system can run automatically and regularly, which further enriches the product database of the CIMISS weather data.
The integrated surface meteorological data processing system is an operational system based on the provincenation unified CIMISS data environment, which can produce in quasireal time the daily, 5day, 10day, monthly, and annual products and meet the needs of the ground meteorological data users after quality control. This paper introduces the development of the integrated realtime meteorological data processing system from the aspects of software requirement analysis, statistical method, function realization, and key technology. By running the strategy configuration, the system can run automatically and regularly, which further enriches the product database of the CIMISS weather data.
2018, 46(3):509-514.
Abstract:
In order to allow tourists to quickly access to weather and travel information and plan their tourist routes reasonably, the Java development kit JDK 17 and Myeclipse development tools are used to design and implement an Androidbased weather APP. The whole system is composed of the mobile client, background management system, Web server, and API interface system. This paper focuses on the design and implementation of main function modules and the API interface system of the APP. The APP aggregates meteorological, geographic and scenic information and uses the IDV graphical products for the first time in China to provide users timely with a convenience access to such service information as tourism destination weather forecasts, traffic meteorology, tourist attractions and others, to enhance the tourism meteorology service capabilities. The developed API interface system integrates the service product resources of the meteorological department, serving not only mobile phone APPs, but also the data querying for meteorological service products on the thirdparty websites to achieve the optimal resource sharing.
In order to allow tourists to quickly access to weather and travel information and plan their tourist routes reasonably, the Java development kit JDK 17 and Myeclipse development tools are used to design and implement an Androidbased weather APP. The whole system is composed of the mobile client, background management system, Web server, and API interface system. This paper focuses on the design and implementation of main function modules and the API interface system of the APP. The APP aggregates meteorological, geographic and scenic information and uses the IDV graphical products for the first time in China to provide users timely with a convenience access to such service information as tourism destination weather forecasts, traffic meteorology, tourist attractions and others, to enhance the tourism meteorology service capabilities. The developed API interface system integrates the service product resources of the meteorological department, serving not only mobile phone APPs, but also the data querying for meteorological service products on the thirdparty websites to achieve the optimal resource sharing.
2018, 46(3):515-523.
Abstract:
The relationship between glazes from 95 surface weather stations in Hunan Province and seaice density and sea surface temperature from 1983 to 2015 is studied by using the experimental orthogonal function analysis (EOF). The results indicate that the frequency of glazes in Hunan Province was 219 per year with the feature of a higher incidence of glazes in south and the southern mountain area compared with the north, the northern mountain area and in the plain. The frequency of glazes shows a tendency of decrease with the increase of time. The glazes in Hunan Province mainly formed in the environment with the condition of high relative humidity, low wind speed and north wind, as well as the minimum temperature between 3 and 0 ℃，and the maximum temperature between 0 to 4 ℃. The number of glazes happened in Hunan Province in winter increased with the increase of the sea ice density from the east of the Severnava Zemlva islands to the north of the Bering Strait, while in the area with the remarkable negative correlation between the frequency of the glazes and the sea surface temperature of the Northwest Pacific, three existed a Cshaped distribution.
The relationship between glazes from 95 surface weather stations in Hunan Province and seaice density and sea surface temperature from 1983 to 2015 is studied by using the experimental orthogonal function analysis (EOF). The results indicate that the frequency of glazes in Hunan Province was 219 per year with the feature of a higher incidence of glazes in south and the southern mountain area compared with the north, the northern mountain area and in the plain. The frequency of glazes shows a tendency of decrease with the increase of time. The glazes in Hunan Province mainly formed in the environment with the condition of high relative humidity, low wind speed and north wind, as well as the minimum temperature between 3 and 0 ℃，and the maximum temperature between 0 to 4 ℃. The number of glazes happened in Hunan Province in winter increased with the increase of the sea ice density from the east of the Severnava Zemlva islands to the north of the Bering Strait, while in the area with the remarkable negative correlation between the frequency of the glazes and the sea surface temperature of the Northwest Pacific, three existed a Cshaped distribution.
2018, 46(3):524-531.
Abstract:
Based on highresolution spatial and temporal data over Ningxia from 1961 to 2015, we analyzed the distribution characteristics of spring droughts by statistical methods. The results reveal that there were more droughts in spring happened in the central Ningxia than in the northern or southern parts, but the average intensity of droughts had contrary characteristics. The maximum spring drought intensity demonstrated obviously multipolar distribution characteristics. There occurred more frequently serious droughts in Wuzhong, Yinchua, and Zhongwei. The frequency of spring droughts in Ningxia increased basically year by year, but the average intensity decreased gradually, while interdecadal characteristics were more obvious. The spring drought intensity was relatively stable, and large scale droughts occurred more frequently in March and May. During early March, early May and late May, serious drought processes occurred more easily. The main reasons for spring droughts in Northwest China include the variation of the ridge of the continental high and 500 hPa atmospheric circulation.
Based on highresolution spatial and temporal data over Ningxia from 1961 to 2015, we analyzed the distribution characteristics of spring droughts by statistical methods. The results reveal that there were more droughts in spring happened in the central Ningxia than in the northern or southern parts, but the average intensity of droughts had contrary characteristics. The maximum spring drought intensity demonstrated obviously multipolar distribution characteristics. There occurred more frequently serious droughts in Wuzhong, Yinchua, and Zhongwei. The frequency of spring droughts in Ningxia increased basically year by year, but the average intensity decreased gradually, while interdecadal characteristics were more obvious. The spring drought intensity was relatively stable, and large scale droughts occurred more frequently in March and May. During early March, early May and late May, serious drought processes occurred more easily. The main reasons for spring droughts in Northwest China include the variation of the ridge of the continental high and 500 hPa atmospheric circulation.
2018, 46(3):532-538.
Abstract:
Solar radiation is the most basic and important energy source of the earth surface. It is very important to analyze the change of the solar radiation for regional climate and agricultural development. This study uses the meteorological data of 4 meteorological stations in the Ebinur Lake oasis area from 1961 to 2013 and the methods of the least squares discriminant analysis, anomaly analysis, MannKendall trend analysis and wavelet analysis to analyze the periodic change regularity of the solar radiation. The results show that: (1) The annual amount of radiation decreased with a relative change rate of 128; the fluctuation was relatively stable. The amount of radiation was mainly concentrated in the period from May to August, accounting for 52% of the year, which showed a normal distribution. A downward trend can be found in all months, with the decline rate being the largest in July. (2) The total amount of radiation in the Ebinur Lake oasis mainly concentrated in summer and autumn; the change trends of the four seasons were basically the same; there appeared the alternative process from lighting to dimming. Through the threshold test at the level of 99%, the amount of radiation showed a mutation in 1986 The change of annual total radiation was basically the same with changes of radiation in four seasons. (3) For the 21year, 10year, and 7year period cycles, there were relatively bright and dark periods, but the oscillation periods were different.
Solar radiation is the most basic and important energy source of the earth surface. It is very important to analyze the change of the solar radiation for regional climate and agricultural development. This study uses the meteorological data of 4 meteorological stations in the Ebinur Lake oasis area from 1961 to 2013 and the methods of the least squares discriminant analysis, anomaly analysis, MannKendall trend analysis and wavelet analysis to analyze the periodic change regularity of the solar radiation. The results show that: (1) The annual amount of radiation decreased with a relative change rate of 128; the fluctuation was relatively stable. The amount of radiation was mainly concentrated in the period from May to August, accounting for 52% of the year, which showed a normal distribution. A downward trend can be found in all months, with the decline rate being the largest in July. (2) The total amount of radiation in the Ebinur Lake oasis mainly concentrated in summer and autumn; the change trends of the four seasons were basically the same; there appeared the alternative process from lighting to dimming. Through the threshold test at the level of 99%, the amount of radiation showed a mutation in 1986 The change of annual total radiation was basically the same with changes of radiation in four seasons. (3) For the 21year, 10year, and 7year period cycles, there were relatively bright and dark periods, but the oscillation periods were different.
2018, 46(3):539-544.
Abstract:
By analyzing the Vertically Integrated Liquid water content (VIL) characteristics for hailstorms in Xining from 2013 to 2016, the identification indexs of VIL in hailstorm warning and hailstorm path instruction are obtained. The results show that the hails in Xining mostly happened after 2 to 4 radar volume scans after maximum VIL, and within 4 to 5 volume scans after VIL increasing abruptly, and 864% of the hailing areas are within 45 to 210 km around the maximum VIL. The thresholds of VIL when hailing are 23 kg〖DK〗·m-2 in June, July and September, 28 kg〖DK〗·m-2 in August, while the abruptincrease values of VIL are 5 kg〖DK〗·m-2 in June and September and 10 kg〖DK〗·m-2 in July and August. The effectiveness test indicates that identification indexs of VIL have good indicativeness for hailstorm warning. The earlywarning of occurring time and hailing area can be conducted by the moving speed and direction extrapolation of VIL.
By analyzing the Vertically Integrated Liquid water content (VIL) characteristics for hailstorms in Xining from 2013 to 2016, the identification indexs of VIL in hailstorm warning and hailstorm path instruction are obtained. The results show that the hails in Xining mostly happened after 2 to 4 radar volume scans after maximum VIL, and within 4 to 5 volume scans after VIL increasing abruptly, and 864% of the hailing areas are within 45 to 210 km around the maximum VIL. The thresholds of VIL when hailing are 23 kg〖DK〗·m-2 in June, July and September, 28 kg〖DK〗·m-2 in August, while the abruptincrease values of VIL are 5 kg〖DK〗·m-2 in June and September and 10 kg〖DK〗·m-2 in July and August. The effectiveness test indicates that identification indexs of VIL have good indicativeness for hailstorm warning. The earlywarning of occurring time and hailing area can be conducted by the moving speed and direction extrapolation of VIL.
2018, 46(3):545-555.
Abstract:
Based on the cloud physical probe data of 11 aircrafts carried out in Guangxi in November and December 2012, the macro and micro physical structure characteristics of stratiform clouds are studied and the precipitation mechanism of stratiform clouds is discussed. The main results show that the microphysical characteristics of stratiform clouds in Guangxi are significantly different from those in other parts of China. The typical vertical microphysical structure of stratiform clouds is: droplets are generated by condensation in the lower layer and develop with the updraft; the number concentration and average diameters of cloud droplets and liquid water content gradually increased with height; the droplet spectrum broadened, and the spectral pattern extended to large scale; they increased to a maximum value at the upper level of the clouds and decreased with height subsequently. The ice particles in the layer of altostratus with a cloud structure of cool and warm mixed affected the microphysical structure after falling into the warm layer, mainly broadening the droplet spectrum and increasing the CIP vertical distribution amplitude of droplet diameters, which was conducive to the initiation and development of the collisioncoalescence process in the warm layer. The microphysical horizontal distribution of the stratocumulus showed discontinuous jump variation and there was the convection bubble structure. The microphysical quantities within the convection bubble were higher than those outside the bubble; cloud droplet spectral pattern varied toward large scale; the convection bubble structure was the important mechanism for the formation of stratocumulus precipitation.
Based on the cloud physical probe data of 11 aircrafts carried out in Guangxi in November and December 2012, the macro and micro physical structure characteristics of stratiform clouds are studied and the precipitation mechanism of stratiform clouds is discussed. The main results show that the microphysical characteristics of stratiform clouds in Guangxi are significantly different from those in other parts of China. The typical vertical microphysical structure of stratiform clouds is: droplets are generated by condensation in the lower layer and develop with the updraft; the number concentration and average diameters of cloud droplets and liquid water content gradually increased with height; the droplet spectrum broadened, and the spectral pattern extended to large scale; they increased to a maximum value at the upper level of the clouds and decreased with height subsequently. The ice particles in the layer of altostratus with a cloud structure of cool and warm mixed affected the microphysical structure after falling into the warm layer, mainly broadening the droplet spectrum and increasing the CIP vertical distribution amplitude of droplet diameters, which was conducive to the initiation and development of the collisioncoalescence process in the warm layer. The microphysical horizontal distribution of the stratocumulus showed discontinuous jump variation and there was the convection bubble structure. The microphysical quantities within the convection bubble were higher than those outside the bubble; cloud droplet spectral pattern varied toward large scale; the convection bubble structure was the important mechanism for the formation of stratocumulus precipitation.
2018, 46(3):556-562.
Abstract:
The hourly precipitation data sets with a spatial resolution of 01°×01°, which is the integrated CMORPH (Climate Prediction Center Morphing) rainfall products, are used to analyze the temporal and spatial distribution of precipitation in the Dabie Mountain region from 2012 to 2014 The average of annual precipitation was 9785 mm over the Dabie Mountain region, and the heavy rain center was located at the southeast of the Dabie Mountain peak. The main rainfall season was from May to July, with obvious topographic character. There is a single peak in the time series of monthly rainfall, and the monthly average precipitation is the most in July in 12 months. As to the spatial distribution, Dabie Mountain and the area to the East had the more rainfall. The heavy rain and storm rainfall occurred more frequently in these regions, and in the central peak area and the eastern part, there were most heavy rain days, increasing with altitude. The location of the precipitation center moved with seasons. In winter, the precipitation center was located at the southeastern part of the peak, and in spring it moved northwestward and was located at the north of the main peak. From September, the center came back to the south of the main peak. It is concluded that the evolvement of atmospheric circulation and the interaction with terrain were the main causes for the orographic precipitation (precipitation increasing with the elevation) and seasonal variation.
The hourly precipitation data sets with a spatial resolution of 01°×01°, which is the integrated CMORPH (Climate Prediction Center Morphing) rainfall products, are used to analyze the temporal and spatial distribution of precipitation in the Dabie Mountain region from 2012 to 2014 The average of annual precipitation was 9785 mm over the Dabie Mountain region, and the heavy rain center was located at the southeast of the Dabie Mountain peak. The main rainfall season was from May to July, with obvious topographic character. There is a single peak in the time series of monthly rainfall, and the monthly average precipitation is the most in July in 12 months. As to the spatial distribution, Dabie Mountain and the area to the East had the more rainfall. The heavy rain and storm rainfall occurred more frequently in these regions, and in the central peak area and the eastern part, there were most heavy rain days, increasing with altitude. The location of the precipitation center moved with seasons. In winter, the precipitation center was located at the southeastern part of the peak, and in spring it moved northwestward and was located at the north of the main peak. From September, the center came back to the south of the main peak. It is concluded that the evolvement of atmospheric circulation and the interaction with terrain were the main causes for the orographic precipitation (precipitation increasing with the elevation) and seasonal variation.
2018, 46(3):563-567.
Abstract:
For the further study of precipitation microphysical characteristics in Shenzhen, The data from the Parsivel laser raindrop spectrometer and rain gauge are used to analyze the precipitation processes of 2015 to 2016 It is found that in case of different precipitation grads, the Parsivel laser raindrop spectrometer has a good correspondence with the rain gauge in measuring minute rainfall, which shows that the Parsivel laser raindrop spectrometer can adapt to the heavy rain environment in Shenzhen. All precipitation processes are classified according to different weather conditions: westerly, southwest monsoon, and tropical cyclone precipitation. The spectral characteristics of the three types of precipitation processes are analyzed. It is found that in the condition of tropical cyclone precipitation, the density of small particles and large particles was the biggest and the smallest respectively, which indicates that the precipitation process was denser. However, in the condition of south west monsoon precipitation, the density of small particles and large particles was the smallest and the biggest respectively, from which we could see that the precipitation was very heavy. The characteristics of westerly precipitation were in between the first two.
For the further study of precipitation microphysical characteristics in Shenzhen, The data from the Parsivel laser raindrop spectrometer and rain gauge are used to analyze the precipitation processes of 2015 to 2016 It is found that in case of different precipitation grads, the Parsivel laser raindrop spectrometer has a good correspondence with the rain gauge in measuring minute rainfall, which shows that the Parsivel laser raindrop spectrometer can adapt to the heavy rain environment in Shenzhen. All precipitation processes are classified according to different weather conditions: westerly, southwest monsoon, and tropical cyclone precipitation. The spectral characteristics of the three types of precipitation processes are analyzed. It is found that in the condition of tropical cyclone precipitation, the density of small particles and large particles was the biggest and the smallest respectively, which indicates that the precipitation process was denser. However, in the condition of south west monsoon precipitation, the density of small particles and large particles was the smallest and the biggest respectively, from which we could see that the precipitation was very heavy. The characteristics of westerly precipitation were in between the first two.
2018, 46(3):568-574.
Abstract:
The SCIT (Strom Cell Identification and Tracking) algorithm is introduced by means of the dynamic template function method for automatically identifying the linear MCS to locate storm cells, further to calculate RLW (Ratio of Length to Width) of MCS. The method is used in more than 20 different types of convections cases with different thresholds. The results demonstrate that the dynamic template function, average RLW and maximum RLW from SCIT can present the linear status of MCS, which are well correlated in the case of different thresholds. The inconsistency is resulted from that the centroid has not enough representativeness and much less storms cells to cause large fluctuation in average RLW and maximum RLW. Comprehensive analysis results show that the dynamic template function method is more stable and reliable, and coincident with the actual situation.
The SCIT (Strom Cell Identification and Tracking) algorithm is introduced by means of the dynamic template function method for automatically identifying the linear MCS to locate storm cells, further to calculate RLW (Ratio of Length to Width) of MCS. The method is used in more than 20 different types of convections cases with different thresholds. The results demonstrate that the dynamic template function, average RLW and maximum RLW from SCIT can present the linear status of MCS, which are well correlated in the case of different thresholds. The inconsistency is resulted from that the centroid has not enough representativeness and much less storms cells to cause large fluctuation in average RLW and maximum RLW. Comprehensive analysis results show that the dynamic template function method is more stable and reliable, and coincident with the actual situation.
2018, 46(3):575-583.
Abstract:
This paper explores the characteristics of the mesoand microscale systems in the southwest vortex during a rainstorm occurred in the Hanzhong basin from 28 to 29 June 2015 under the influence of the southwest vortex. For reference, the data of Doppler radar, NECP reanalysis, conventional observation and automatic meteorological stations are utilized. Under the 850 hPa the southwest vortex, the rainstorm formed by the combined effect of 700 hPa lowlevel jet stream and the upper divergence at the tropopause. The Foping and Zhenba, which locate at the northeast of the southwest vortex, were two mainly heavy rainfall areas. In the radar intensity field, the supercell kept developing in the northeast of southwest vortex for approximately 15 to 2 hours, which corresponds two heavy rainfall centers with the echo intensity reaching the highest (58 dBz), and in the velocity field, the supercells were accompanied by deep mesocyclones, which appeared at the southwest and central parts of the supercells. Besides there existed a banded adverse wind area over Zhengba. The results indicate that it was the supercell in a mesoscale 〖JP2〗convective complex in the southwest vortex, directly leading to the torrential rainfall (709 mm/h 〖JP〗and 321 mm/h) in Foping and Zhengba. The intensity change of the supercell determined the development of rainstorms in the Hanzhong basin. Meanwhile, we summarize the characteristics of the echoes with different magnitude, which provides a theoretical basis for rainstorm prediction.
This paper explores the characteristics of the mesoand microscale systems in the southwest vortex during a rainstorm occurred in the Hanzhong basin from 28 to 29 June 2015 under the influence of the southwest vortex. For reference, the data of Doppler radar, NECP reanalysis, conventional observation and automatic meteorological stations are utilized. Under the 850 hPa the southwest vortex, the rainstorm formed by the combined effect of 700 hPa lowlevel jet stream and the upper divergence at the tropopause. The Foping and Zhenba, which locate at the northeast of the southwest vortex, were two mainly heavy rainfall areas. In the radar intensity field, the supercell kept developing in the northeast of southwest vortex for approximately 15 to 2 hours, which corresponds two heavy rainfall centers with the echo intensity reaching the highest (58 dBz), and in the velocity field, the supercells were accompanied by deep mesocyclones, which appeared at the southwest and central parts of the supercells. Besides there existed a banded adverse wind area over Zhengba. The results indicate that it was the supercell in a mesoscale 〖JP2〗convective complex in the southwest vortex, directly leading to the torrential rainfall (709 mm/h 〖JP〗and 321 mm/h) in Foping and Zhengba. The intensity change of the supercell determined the development of rainstorms in the Hanzhong basin. Meanwhile, we summarize the characteristics of the echoes with different magnitude, which provides a theoretical basis for rainstorm prediction.
2018, 46(3):584-593.
Abstract:
Based on the observation data and ECWMF 6hour reanalysis data and the Southwest Regional Numerical Prediction Model, a very severe snowstorm occurred in the middle east of the Western Sichuan Plateau in 21 February 2016 is analyzed and diagnosed. The results show that the snowstorm was mainly related to the southwest jet and the frontogenesis formed in the combination with the cold air and southwest warm and humid airflow. The cold air to the south of the horizontal trough of Baikal was incorporated into the low trough in the central Western Sichuan Plateau. The Bay of Bengal and South China Sea are the sources of the vapor of the snowstorm as the subtropical high moves northward. The heavy snowfall occurred when Slantwise Vorticity Development (SVD) strongly developed and the snowstorm area was the same as the strongest zone for SVD development. The Southwest Regional Numerical Forecast Model made the accurate forecast 6 hours in advance of the snowstorm’s potential field and physical field. The precipitation forecast was one order of magnitude weaker than the actual precipitation, and the falling zone forecast of the snowstorm was more accurate than its strength forecast.
Based on the observation data and ECWMF 6hour reanalysis data and the Southwest Regional Numerical Prediction Model, a very severe snowstorm occurred in the middle east of the Western Sichuan Plateau in 21 February 2016 is analyzed and diagnosed. The results show that the snowstorm was mainly related to the southwest jet and the frontogenesis formed in the combination with the cold air and southwest warm and humid airflow. The cold air to the south of the horizontal trough of Baikal was incorporated into the low trough in the central Western Sichuan Plateau. The Bay of Bengal and South China Sea are the sources of the vapor of the snowstorm as the subtropical high moves northward. The heavy snowfall occurred when Slantwise Vorticity Development (SVD) strongly developed and the snowstorm area was the same as the strongest zone for SVD development. The Southwest Regional Numerical Forecast Model made the accurate forecast 6 hours in advance of the snowstorm’s potential field and physical field. The precipitation forecast was one order of magnitude weaker than the actual precipitation, and the falling zone forecast of the snowstorm was more accurate than its strength forecast.
2018, 46(3):594-604.
Abstract:
A convective Meiyu rainstorm took place in Wuhan from 5 to 6 July 2016, which caused serious urban water logging. The convective clouds influencing the weather system and physical elements are studied. The results show: (1) The convective clouds came from the eastern Jianghan Plain. During the heavy rain in Wuhan, two β convective cells merged at the first stage, and two 〖WTBX〗β〖WTBZ〗 convective cells merged with 〖WTBX〗α〖WTBZ〗 cloud successively at the second stage, in which rainfall in Wuhan strengthened dramatically. At the last stage, because the convective cloud cluster passed Wuhan without obvious merger, the heavy rainfall began to reduce, though there appeared the westward fingerlike convective clouds. (2) The heavy rain took place while the subtropical high was strengthening and moving westward. During the rainstorm, Wuhan was located at the northeast side of the ridge stretching eastward from the South Asia high at 200 hPa. The zonal shear line turned to a trough and moved eastward at 500 hPa; the vortex maintained over the Jianghan plain at 850 hPa. It was a favorable condition for the heavy rain that Wuhan was in the water vapor divergence zone locating at the left side of the northerly wind jet at 200 hPa, coupling with the water vapor convergence zone in front of the lowlevel southerly jet at 850 hPa.(3) As the wind direction over Wuhan turned out to be northwest at 200 hPa, wind speed increased at 500 hPa, both vertical shear between 200 hPa and 850 hPa and between 500 hPa and 850 hPa increased dramatically. Dry air appeared at 400 hPa. These three factors motivated the rainstorm to burst.
A convective Meiyu rainstorm took place in Wuhan from 5 to 6 July 2016, which caused serious urban water logging. The convective clouds influencing the weather system and physical elements are studied. The results show: (1) The convective clouds came from the eastern Jianghan Plain. During the heavy rain in Wuhan, two β convective cells merged at the first stage, and two 〖WTBX〗β〖WTBZ〗 convective cells merged with 〖WTBX〗α〖WTBZ〗 cloud successively at the second stage, in which rainfall in Wuhan strengthened dramatically. At the last stage, because the convective cloud cluster passed Wuhan without obvious merger, the heavy rainfall began to reduce, though there appeared the westward fingerlike convective clouds. (2) The heavy rain took place while the subtropical high was strengthening and moving westward. During the rainstorm, Wuhan was located at the northeast side of the ridge stretching eastward from the South Asia high at 200 hPa. The zonal shear line turned to a trough and moved eastward at 500 hPa; the vortex maintained over the Jianghan plain at 850 hPa. It was a favorable condition for the heavy rain that Wuhan was in the water vapor divergence zone locating at the left side of the northerly wind jet at 200 hPa, coupling with the water vapor convergence zone in front of the lowlevel southerly jet at 850 hPa.(3) As the wind direction over Wuhan turned out to be northwest at 200 hPa, wind speed increased at 500 hPa, both vertical shear between 200 hPa and 850 hPa and between 500 hPa and 850 hPa increased dramatically. Dry air appeared at 400 hPa. These three factors motivated the rainstorm to burst.
2018, 46(3):605-618.
Abstract:
Using a variety of observational data and NCEP/NCAR 1°×1° reanalysis data, a diagnostic analysis is made of two consecutive heavy rainfall events on 30 July and 1 August 2012 in the northwestern Shandong Province. The results show that the heavy rainfall formed in the warm air around the south edge of the subtropical high in front of the steady westerly trough; a typhoon moved northward along the coast of Southeast China; the subtropical high strengthened and moved northward; which provided a synoptic background for the heavy rainfall events for two consecutive days. At the lower level blow 925 hPa, both the southeast winds from the southeast coast and the east winds from Bohai provided moisture and energy supply for the heavy rainfall, leading to higher humidity, high temperature, convective instability, and high CAPE. The first heavy rain occurred in south winds and warm air with strong intensity and short duration. During the second heavy rain, the lowlevel cold air invaded and the warm air were lifted; there was convective precipitation in the early stage and stable rainfall in the later, with weaker intensity and longer duration. The shear line with a reverse trough and mesoscale vortex circulation in 850 hPa and below were the influencing systems for the heavy rainfall events. At lower levels, the northeast air flow from the Bohai Sea and the southeast warm air from the coast of Southeast China generated a mesoscale vortex, which induced cyclonic converging ascending and triggered the release of instable convective energy. Convective cloud clusters formed a stable Mesoscale Convective System (MCS) in the northwestern Shandong, resulting in obvious train effect and backwardpropagation characteristic. The heavy rainfall had a strong diurnal variation, enhanced at night and weakened in daytime.
Using a variety of observational data and NCEP/NCAR 1°×1° reanalysis data, a diagnostic analysis is made of two consecutive heavy rainfall events on 30 July and 1 August 2012 in the northwestern Shandong Province. The results show that the heavy rainfall formed in the warm air around the south edge of the subtropical high in front of the steady westerly trough; a typhoon moved northward along the coast of Southeast China; the subtropical high strengthened and moved northward; which provided a synoptic background for the heavy rainfall events for two consecutive days. At the lower level blow 925 hPa, both the southeast winds from the southeast coast and the east winds from Bohai provided moisture and energy supply for the heavy rainfall, leading to higher humidity, high temperature, convective instability, and high CAPE. The first heavy rain occurred in south winds and warm air with strong intensity and short duration. During the second heavy rain, the lowlevel cold air invaded and the warm air were lifted; there was convective precipitation in the early stage and stable rainfall in the later, with weaker intensity and longer duration. The shear line with a reverse trough and mesoscale vortex circulation in 850 hPa and below were the influencing systems for the heavy rainfall events. At lower levels, the northeast air flow from the Bohai Sea and the southeast warm air from the coast of Southeast China generated a mesoscale vortex, which induced cyclonic converging ascending and triggered the release of instable convective energy. Convective cloud clusters formed a stable Mesoscale Convective System (MCS) in the northwestern Shandong, resulting in obvious train effect and backwardpropagation characteristic. The heavy rainfall had a strong diurnal variation, enhanced at night and weakened in daytime.
2018, 46(3):619-624.
Abstract:
AgI pyrotechnic nucleants are important seeding agents used in cold cloud seeding operation of weather modification. Currently, several kinds of AgI pyrotechnic nucleants are being used in weather modification operation in China, and their differences in ice nucleating properties need to be evaluated through the uniform test method. In this study, seven kinds of AgI pyrotechnic nucleants, numbered from 1 to 7, were tested in an 1m3 isothermal cloud chamber, and their ice nucleating properties including ice nucleation effectiveness and nucleation rate are compared. The results show that the orders of the ice nuclei numbers calculated by the pyrotechnic nucleant per a gram are in the range of 1010(-8 ℃) to 1013(-18 ℃), and the variation of ice nucleation effectiveness versus temperature can be expressed reasonably by the exponential function. In the low temperature section (≤-16 ℃), high ice nucleation effectiveness can be achieved by various AgI pyrotechnic nucleants. The differences in nucleation effectiveness among those AgI pyrotechnic nucleants in low temperature section are smaller than those in high temperature section (>-16 ℃). In the high temperature section, No.3, No.4 and No.7 samples of pyrotechnic nucleants show higher ice nucleation effectiveness than other four pyrotechnic nucleants. The nucleation rates of all pyrotechnic nucleants are also not the same. The time of 90% AgI ice nuclei grown into ice crystals are in the range of 78 to 18 minutes for various pyrotechnic nucleants when the temperature is at-8 ℃, and the slow nucleation processes such as contactfreezing nucleation may be the main nucleation mechanism of AgI ice nuclei produced by all AgI pyrotechnic nucleants at this temperature.
AgI pyrotechnic nucleants are important seeding agents used in cold cloud seeding operation of weather modification. Currently, several kinds of AgI pyrotechnic nucleants are being used in weather modification operation in China, and their differences in ice nucleating properties need to be evaluated through the uniform test method. In this study, seven kinds of AgI pyrotechnic nucleants, numbered from 1 to 7, were tested in an 1m3 isothermal cloud chamber, and their ice nucleating properties including ice nucleation effectiveness and nucleation rate are compared. The results show that the orders of the ice nuclei numbers calculated by the pyrotechnic nucleant per a gram are in the range of 1010(-8 ℃) to 1013(-18 ℃), and the variation of ice nucleation effectiveness versus temperature can be expressed reasonably by the exponential function. In the low temperature section (≤-16 ℃), high ice nucleation effectiveness can be achieved by various AgI pyrotechnic nucleants. The differences in nucleation effectiveness among those AgI pyrotechnic nucleants in low temperature section are smaller than those in high temperature section (>-16 ℃). In the high temperature section, No.3, No.4 and No.7 samples of pyrotechnic nucleants show higher ice nucleation effectiveness than other four pyrotechnic nucleants. The nucleation rates of all pyrotechnic nucleants are also not the same. The time of 90% AgI ice nuclei grown into ice crystals are in the range of 78 to 18 minutes for various pyrotechnic nucleants when the temperature is at-8 ℃, and the slow nucleation processes such as contactfreezing nucleation may be the main nucleation mechanism of AgI ice nuclei produced by all AgI pyrotechnic nucleants at this temperature.
2018, 46(3):625-630.
Abstract:
In order to improve the power meteorological service and provide human comfort index prediction according to the demand of power load forecasting in Tianjin. We use the power load data and meteorological data in summer from 2002 to 2005 in Tianjin to calculate the human comfort index. The results of various models and the corresponding relationship between mean temperature and power load are analyzed in detail. The results show that some models are more accordant with the feeling of body comfort and has better linear dependence with meteorological power loads, such as UTCI (Universal Thermal Climate Index), Lyu Weilin outdoor model and Li Yuan model. In order to build a better human comfort index model for Tianjin, the least squares method is applied to correct the Lyu Weilin model, which is widely used in China.
In order to improve the power meteorological service and provide human comfort index prediction according to the demand of power load forecasting in Tianjin. We use the power load data and meteorological data in summer from 2002 to 2005 in Tianjin to calculate the human comfort index. The results of various models and the corresponding relationship between mean temperature and power load are analyzed in detail. The results show that some models are more accordant with the feeling of body comfort and has better linear dependence with meteorological power loads, such as UTCI (Universal Thermal Climate Index), Lyu Weilin outdoor model and Li Yuan model. In order to build a better human comfort index model for Tianjin, the least squares method is applied to correct the Lyu Weilin model, which is widely used in China.
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.