Volume 40,Issue 1,2012 Table of Contents
2012, 40(1):1-4.
Abstract:
The transmitter driver is a very important part of CINRAD/SA and SB Radar. Its technical parameters not only determine the basical output RF pulse and spectrum of the transmitter, but also influence directly the operating quality of the radar system. The operating principles of the CINRAD/SA and SB Radar transmitter driver are discussed in details, and a thorough hardware analysis is made of the working diagram of the driver, which comprised 3A4 and 3A5. Also some useful adjustment methods and a number of keypoint waveforms, as well as the related timing sequence, are introduced. According to the radar system maintenance experiences, some basic electronic troubleshooting thoughts and quick maintenance methods are discussed and summarized, in combination with the relevant alarm massages.
The transmitter driver is a very important part of CINRAD/SA and SB Radar. Its technical parameters not only determine the basical output RF pulse and spectrum of the transmitter, but also influence directly the operating quality of the radar system. The operating principles of the CINRAD/SA and SB Radar transmitter driver are discussed in details, and a thorough hardware analysis is made of the working diagram of the driver, which comprised 3A4 and 3A5. Also some useful adjustment methods and a number of keypoint waveforms, as well as the related timing sequence, are introduced. According to the radar system maintenance experiences, some basic electronic troubleshooting thoughts and quick maintenance methods are discussed and summarized, in combination with the relevant alarm massages.
2012, 40(1):5-8.
Abstract:
Since 2008, the degradation of system performance parameters of analog IF receiver has caused the poor reliability and stability and higher failure rate of the CINRAD/SA radar at Jinan. In order to better ensure the normal operation of the weather radar, the IFD (Digital Intermediate Frequency) upgrade project was completed in July 2009. After transformation, the phase noise of the IFD radar is very stable and the velocity information is more credible and accurate. The working principles of the IFD receiver are introduced, with the emphases on the problems in the software and hardware and their solutions about the installation, debugging and transformation of the IFD devices. In addition, the technical parameter tests after transformation is also summarized, to provide references to radar maintenance staff.
Since 2008, the degradation of system performance parameters of analog IF receiver has caused the poor reliability and stability and higher failure rate of the CINRAD/SA radar at Jinan. In order to better ensure the normal operation of the weather radar, the IFD (Digital Intermediate Frequency) upgrade project was completed in July 2009. After transformation, the phase noise of the IFD radar is very stable and the velocity information is more credible and accurate. The working principles of the IFD receiver are introduced, with the emphases on the problems in the software and hardware and their solutions about the installation, debugging and transformation of the IFD devices. In addition, the technical parameter tests after transformation is also summarized, to provide references to radar maintenance staff.
3 Study of Spectral Moment Estimations for WindProfiling Radar Based on Maximum Likelihood Algorithm
2012, 40(1):9-14.
Abstract:
In the spectral processing of wind profile radar data, there often appear clutters, intermittent clutters, and the mixture of atmospheric echoes and geomagnetic clutters. In order to effectively restrain and remove the clutters and increase the wind profile radar detection range and accuracy, the effective spectral moment estimation must be conducted on the spectral moments of atmospheric echo spectrums. Through the power spectral analysis of wind profile radar Doppler echoes, a method of wind profiler radar echo spectral data estimation is presented based on the maximum likelihood method. The MATLAB simulation analysis is conducted, and compared with the conventional method, the feasibility and effectiveness of the algorithm is verified. The spectrum moment estimation has been improved significantly by sampling from the lowerlevel volume.
In the spectral processing of wind profile radar data, there often appear clutters, intermittent clutters, and the mixture of atmospheric echoes and geomagnetic clutters. In order to effectively restrain and remove the clutters and increase the wind profile radar detection range and accuracy, the effective spectral moment estimation must be conducted on the spectral moments of atmospheric echo spectrums. Through the power spectral analysis of wind profile radar Doppler echoes, a method of wind profiler radar echo spectral data estimation is presented based on the maximum likelihood method. The MATLAB simulation analysis is conducted, and compared with the conventional method, the feasibility and effectiveness of the algorithm is verified. The spectrum moment estimation has been improved significantly by sampling from the lowerlevel volume.
2012, 40(1):15-19.
Abstract:
The design ideas and features of the transmitter control system of the TWP3 boundarylayer wind profiler, which was located in the World Expo Park, are described. Based on the effective mechanism of repetitive judgment and reset, the control system implements the online monitoring of the transmitter, RF switch control, fault location, and selfprotection by the programmable language FPGA and microcontroller. The sampled data for the control circuit includes voltages, temperature and RF signals, and fault information which would be visually displayed on the screen of the transmitter and also be uploaded to computers. The control system played an important role in debugging the transmitter and relative parts of the wind profiler.
The design ideas and features of the transmitter control system of the TWP3 boundarylayer wind profiler, which was located in the World Expo Park, are described. Based on the effective mechanism of repetitive judgment and reset, the control system implements the online monitoring of the transmitter, RF switch control, fault location, and selfprotection by the programmable language FPGA and microcontroller. The sampled data for the control circuit includes voltages, temperature and RF signals, and fault information which would be visually displayed on the screen of the transmitter and also be uploaded to computers. The control system played an important role in debugging the transmitter and relative parts of the wind profiler.
2012, 40(1):20-24.
Abstract:
When a homemade pryanometer was calibrated， the uncertainty of the measurement result is caused by many factors， such as the measurement reproducibility， standard instrument， temperature change， incident angle， time response， nonlinearity， zero offset， multimeter error， the operation error， spectral response error， and so on. According to 〖WTBX〗〖STBX〗JJF10591999 Evaluation and Expression of Uncertainty in Measurement〖WTBZ〗〖STBZ〗， the uncertainty evaluation for the calibration results of homemade pyranometers is conducted. The sources of uncertainty are pointed out， which obviously influence the measurement results. The uncertainty components are evaluated quantitatively. The results show that when the calibration environmental requirements are satisfied， the expanded uncertainty of the results of the pyranometer is 3.4% （〖WTBX〗k〖WTBZ〗=1.98）， in which the uncertainty component caused by the error of the incident angle is maximal. Therefore， the characteristics such as the cosine response， azimuth response， and nonlinearity of the new pyranometer should be tested to ensure the measurement accuracy.
When a homemade pryanometer was calibrated， the uncertainty of the measurement result is caused by many factors， such as the measurement reproducibility， standard instrument， temperature change， incident angle， time response， nonlinearity， zero offset， multimeter error， the operation error， spectral response error， and so on. According to 〖WTBX〗〖STBX〗JJF10591999 Evaluation and Expression of Uncertainty in Measurement〖WTBZ〗〖STBZ〗， the uncertainty evaluation for the calibration results of homemade pyranometers is conducted. The sources of uncertainty are pointed out， which obviously influence the measurement results. The uncertainty components are evaluated quantitatively. The results show that when the calibration environmental requirements are satisfied， the expanded uncertainty of the results of the pyranometer is 3.4% （〖WTBX〗k〖WTBZ〗=1.98）， in which the uncertainty component caused by the error of the incident angle is maximal. Therefore， the characteristics such as the cosine response， azimuth response， and nonlinearity of the new pyranometer should be tested to ensure the measurement accuracy.
2012, 40(1):25-30.
Abstract:
To explore the causes of the differences in water vapor pressure measurements between manual and automatic weather stations, based on the data of hourly air pressure, dry bulb temperature, and wet bulb temperature from 134 national reference climate stations, by using the water vapor pressure formulas on manual observation weather station and automatic weather station respectively, the regularities of water vapor pressure variation are studied corresponding to the increments of the station air pressure, dry bulb temperature, wet bulb temperature, automatic weather station temperature, and relative humidity. Through analyzing the meteorological observation data, the causes of the differences in water vapor pressure measurments between manual and automatic weather stations are discussed. Through the simulation and analysis of actual observation data, it is found that the influence of the systematic errors of air pressure and dry bulb temperature on the difference in water vapor pressure measurments between manual and automatic weather stations is very small, while the influences of the relative humidity and temperature of automatic weather stations are significant, especially relative humidity. For the given systematic errors of relative humidity and temperature of automatic weather stations, the variation range of the differences in water vapor pressure measurments varies with temperature, the higher the temperature, the greater the differences of water vapor pressure.
To explore the causes of the differences in water vapor pressure measurements between manual and automatic weather stations, based on the data of hourly air pressure, dry bulb temperature, and wet bulb temperature from 134 national reference climate stations, by using the water vapor pressure formulas on manual observation weather station and automatic weather station respectively, the regularities of water vapor pressure variation are studied corresponding to the increments of the station air pressure, dry bulb temperature, wet bulb temperature, automatic weather station temperature, and relative humidity. Through analyzing the meteorological observation data, the causes of the differences in water vapor pressure measurments between manual and automatic weather stations are discussed. Through the simulation and analysis of actual observation data, it is found that the influence of the systematic errors of air pressure and dry bulb temperature on the difference in water vapor pressure measurments between manual and automatic weather stations is very small, while the influences of the relative humidity and temperature of automatic weather stations are significant, especially relative humidity. For the given systematic errors of relative humidity and temperature of automatic weather stations, the variation range of the differences in water vapor pressure measurments varies with temperature, the higher the temperature, the greater the differences of water vapor pressure.
2012, 40(1):31-34.
Abstract:
The Vaisala RS92 radiosonde represents the higher level of radiosondes and can be used as the benchmark to estimate other radiosondes types. Its performance can be evaluated according to the practical sounding data besides the indexes provided. The comparison method is used to analyze the data acquired from two Vaisala RS92 radiosondes which was released by the same balloon, and the statistical data from the same time of different days are compared to ascertain the performance of the radiosondes for sounding temperature, pressure, and humidity. The results indicate that the RS92 radiosonde has good measuring consistency performance in sounding temperature, pressure, and humidity， which could be used as the standard radiosonde to determine the measuring performance of other radiosondes types.
The Vaisala RS92 radiosonde represents the higher level of radiosondes and can be used as the benchmark to estimate other radiosondes types. Its performance can be evaluated according to the practical sounding data besides the indexes provided. The comparison method is used to analyze the data acquired from two Vaisala RS92 radiosondes which was released by the same balloon, and the statistical data from the same time of different days are compared to ascertain the performance of the radiosondes for sounding temperature, pressure, and humidity. The results indicate that the RS92 radiosonde has good measuring consistency performance in sounding temperature, pressure, and humidity， which could be used as the standard radiosonde to determine the measuring performance of other radiosondes types.
2012, 40(1):35-40.
Abstract:
The splits window algorithm is used to retrieve the snow surface temperature from MODIS 1B data through redeveloping the ENVI software. The details of image processing and programming are given. Taking the northern Xinjiang as an example， the approach is used to calculate the snow surface temperature， and the retrieved results are compared with the observed snow temperatures from automatical meteorological stations. The comparison indicates that the retrieved snow surface temperature distribution is consistent with observed one， and the average error is 1.73 ℃， which is acceptable， can basically reflect the distribution of snow surface temperature over the northern Xinjiang. With the method， the batch processing of remote sensing data can be realized， so to build a long time sequence rapidly and accurately.
The splits window algorithm is used to retrieve the snow surface temperature from MODIS 1B data through redeveloping the ENVI software. The details of image processing and programming are given. Taking the northern Xinjiang as an example， the approach is used to calculate the snow surface temperature， and the retrieved results are compared with the observed snow temperatures from automatical meteorological stations. The comparison indicates that the retrieved snow surface temperature distribution is consistent with observed one， and the average error is 1.73 ℃， which is acceptable， can basically reflect the distribution of snow surface temperature over the northern Xinjiang. With the method， the batch processing of remote sensing data can be realized， so to build a long time sequence rapidly and accurately.
2012, 40(1):41-45.
Abstract:
Groundbased GPS technology has recognized as a tool to observe the atmosphere water vapor with the highest potential. The zenith wet delay (ZWD) is the key factor to obtain water vapor with high precision. The BERNESE software developed by the Astronomical Institute, University of Bern is one of most distinguishing means for calculating ZWD. The basic steps and relevant settings using the BERNESE software to calculate ZWD are introduced on the basis of the data from the continuously operating reference stations over Hongkong, and some special cases are studied, such as having meteorological observation files and calculating ZWD continuously for adjacent days and weeks, or calculating ZWD at some specific time points. The results indicate that the BERNESE software can be used to calculate ZWD perfectly.
Groundbased GPS technology has recognized as a tool to observe the atmosphere water vapor with the highest potential. The zenith wet delay (ZWD) is the key factor to obtain water vapor with high precision. The BERNESE software developed by the Astronomical Institute, University of Bern is one of most distinguishing means for calculating ZWD. The basic steps and relevant settings using the BERNESE software to calculate ZWD are introduced on the basis of the data from the continuously operating reference stations over Hongkong, and some special cases are studied, such as having meteorological observation files and calculating ZWD continuously for adjacent days and weeks, or calculating ZWD at some specific time points. The results indicate that the BERNESE software can be used to calculate ZWD perfectly.
2012, 40(1):46-51.
Abstract:
In order to satisfy the needs of the public meteorological services， taking full advantage of the GPRS network for its wide coverage， realtime online， high quality communication， and low maintenance costs， a LED screen meteorological information broadcast system based on the GPRS network is designed and established. The structure and functions of the system， the hardware configuration， and the display process of the remotecontrol card for the LED screen are described. Three management programs in the system server and the terminal user programs are introduced. The method for converting vectorfont characters to lattice characters is elaborated. The application of this system in practice is also discussed.
In order to satisfy the needs of the public meteorological services， taking full advantage of the GPRS network for its wide coverage， realtime online， high quality communication， and low maintenance costs， a LED screen meteorological information broadcast system based on the GPRS network is designed and established. The structure and functions of the system， the hardware configuration， and the display process of the remotecontrol card for the LED screen are described. Three management programs in the system server and the terminal user programs are introduced. The method for converting vectorfont characters to lattice characters is elaborated. The application of this system in practice is also discussed.
2012, 40(1):52-56.
Abstract:
An analysis is made of some typical cases selected from the faults encountered in the operational maintenance of the meteorological information system. The corresponding countermeasures are presented. In the case of failure in uplink packet transmission and firewall equipments resulting in abnormal data reception， the exclusion method is adopted， with which the scope of failure can be narrowed quickly， so to locate failure points， and according to the routing trend of the network topological graph， the method of segmental check is used to quickly track the location of packet transmission failure caused by abnormal communication network. In the case of downlink packet transmission failure， the causes can be found quickly by means of the method of reverse direction， according to the flow of meteorological data downlink broadcast.
An analysis is made of some typical cases selected from the faults encountered in the operational maintenance of the meteorological information system. The corresponding countermeasures are presented. In the case of failure in uplink packet transmission and firewall equipments resulting in abnormal data reception， the exclusion method is adopted， with which the scope of failure can be narrowed quickly， so to locate failure points， and according to the routing trend of the network topological graph， the method of segmental check is used to quickly track the location of packet transmission failure caused by abnormal communication network. In the case of downlink packet transmission failure， the causes can be found quickly by means of the method of reverse direction， according to the flow of meteorological data downlink broadcast.
2012, 40(1):57-60.
Abstract:
The meteorological network database for Qinghai is based on the B/S structure and developed with the “.NET” platform. The system consists of meteorological database, management website, and spatial information platform. The functions of this system include automatic data storage, base map rendering, data query and statistics, graphic plotting， and so on. The system is convenient to display query results on the electronic map, has been put to operational use at the Qinghai Meteorological Observatory since 2009. It enhanced the data sharing capability and improved the services of the Qinghai Meteorological Observatory. SharpMap is used to provide the WebGIS function and advanced technologies such as Ajax， to increase the system efficiency.
The meteorological network database for Qinghai is based on the B/S structure and developed with the “.NET” platform. The system consists of meteorological database, management website, and spatial information platform. The functions of this system include automatic data storage, base map rendering, data query and statistics, graphic plotting， and so on. The system is convenient to display query results on the electronic map, has been put to operational use at the Qinghai Meteorological Observatory since 2009. It enhanced the data sharing capability and improved the services of the Qinghai Meteorological Observatory. SharpMap is used to provide the WebGIS function and advanced technologies such as Ajax， to increase the system efficiency.
13 Management and Retrieval System of Ground Meteorological Observation Data for CountyLevel Stations
2012, 40(1):61-64.
Abstract:
In order to adapt to the modernization of meteorological service and the needs of weather forecasting and agrometeorological researches， making use of VB 6.0 language， a Windowsbased meteorological data management system is built for Wuwei. The system design flow and ideas， the main technical features， and the functions of data storage and application are introduced in detail. With the system， the effective management of the historical meteorological data can be realized， and the way of data retrieval and statistic is improved. The system has become one of important tools in the operational services， being applicable and worth popularizing for countylevel meteorological stations.
In order to adapt to the modernization of meteorological service and the needs of weather forecasting and agrometeorological researches， making use of VB 6.0 language， a Windowsbased meteorological data management system is built for Wuwei. The system design flow and ideas， the main technical features， and the functions of data storage and application are introduced in detail. With the system， the effective management of the historical meteorological data can be realized， and the way of data retrieval and statistic is improved. The system has become one of important tools in the operational services， being applicable and worth popularizing for countylevel meteorological stations.
2012, 40(1):65-73.
Abstract:
A brief review is made of the characteristics of intraseasonal oscillation (MaddenJulian Oscillation) and ENSO (ElNino/Southern Oscillation), as well as the relationships between them.The modulation impacts of MJO and ENSO on the tropical cyclone (TC) activities are summarized, involving the impact on TC formation, intensity, track, lifespan, etc. The respective dynamical mechanisms, the problems and prospects in this field are also discussed briefly as well.
A brief review is made of the characteristics of intraseasonal oscillation (MaddenJulian Oscillation) and ENSO (ElNino/Southern Oscillation), as well as the relationships between them.The modulation impacts of MJO and ENSO on the tropical cyclone (TC) activities are summarized, involving the impact on TC formation, intensity, track, lifespan, etc. The respective dynamical mechanisms, the problems and prospects in this field are also discussed briefly as well.
2012, 40(1):74-78.
Abstract:
In order to study the role of wind profile data in rain storm forecasting, a rain storm event in Dali between 1 and 2 June 2008 is analyzed. The variation of threedimensional fluctuating wind field was noticeable before precipitation, and there was the vertical velocity shear of horizontal winds, and the maximum sounding height increased. By means of the wind profile data, the characteristics of precipitation can be judged. There appeared a doublepeaked power spectra density during precipitation, and the velocities of the vertical stream and the sinking particles can be determined.
In order to study the role of wind profile data in rain storm forecasting, a rain storm event in Dali between 1 and 2 June 2008 is analyzed. The variation of threedimensional fluctuating wind field was noticeable before precipitation, and there was the vertical velocity shear of horizontal winds, and the maximum sounding height increased. By means of the wind profile data, the characteristics of precipitation can be judged. There appeared a doublepeaked power spectra density during precipitation, and the velocities of the vertical stream and the sinking particles can be determined.
2012, 40(1):79-86.
Abstract:
The recent progresses in researches on extreme precipitation over China are reviewed from the aspects of the thresholds， characteristics of variations， possible affecting factors， and simulation. The results indicate that recently the definitions of the thresholds are already clear and definite， and the longterm changes of extreme precipitation have obvious regional characteristics. Because the precipitation in China is affected by the various members of the East Asian climate system and the formation mechanisms are very complicated， the researches on the causes are not thorough enough. There are still some uncertainties in the simulation and estimation with the related application models.
The recent progresses in researches on extreme precipitation over China are reviewed from the aspects of the thresholds， characteristics of variations， possible affecting factors， and simulation. The results indicate that recently the definitions of the thresholds are already clear and definite， and the longterm changes of extreme precipitation have obvious regional characteristics. Because the precipitation in China is affected by the various members of the East Asian climate system and the formation mechanisms are very complicated， the researches on the causes are not thorough enough. There are still some uncertainties in the simulation and estimation with the related application models.
17 Analysis of Extreme Precipitation Events in Rainy Season over Huaihe River Basin from 1961 to 2008
2012, 40(1):87-91.
Abstract:
Using the daily precipitation data of rainy season （June to August） from 1961 to 2008 of 117 stations over the Huaihe River Basin， the extreme precipitation thresholds are determined for different stations by means of the percentile method， and then the time series of extreme precipitation events in recent 48 years is constructed， by which the characteristics of temporalspatial variations of extreme precipitation events are analyzed. The results show that the interannual variation of extreme precipitation is remarkable over the Huaihe River Basin in rainy season， and the amount of extreme precipitation corresponds well with the droughts and floods. The frequency of extreme precipitation events greatly affects the amount of total precipitation in rainy season. The consistency distribution is the main spatial mode in the frequency of extreme precipitation events in the Huaihe River Basin， which can be divided into five main regions: central and eastern， central and north， southwest， northwest， and southern. The amount and frequency of extreme precipitation for the Huaihe River Basin have obvious increase trends in general since the 1960s， and the most significant increasing tendency occurred in the central and western Huaihe River Basin in particular. There are periodic variations of 2 to 3 years in the frequency of extreme precipitation events over the Huaihe River basin in rainy season. There occurred an abrupt change around 2003， and the frequency of extreme precipitation events increased significantly at a significant level of 0.05 since 2003.
Using the daily precipitation data of rainy season （June to August） from 1961 to 2008 of 117 stations over the Huaihe River Basin， the extreme precipitation thresholds are determined for different stations by means of the percentile method， and then the time series of extreme precipitation events in recent 48 years is constructed， by which the characteristics of temporalspatial variations of extreme precipitation events are analyzed. The results show that the interannual variation of extreme precipitation is remarkable over the Huaihe River Basin in rainy season， and the amount of extreme precipitation corresponds well with the droughts and floods. The frequency of extreme precipitation events greatly affects the amount of total precipitation in rainy season. The consistency distribution is the main spatial mode in the frequency of extreme precipitation events in the Huaihe River Basin， which can be divided into five main regions: central and eastern， central and north， southwest， northwest， and southern. The amount and frequency of extreme precipitation for the Huaihe River Basin have obvious increase trends in general since the 1960s， and the most significant increasing tendency occurred in the central and western Huaihe River Basin in particular. There are periodic variations of 2 to 3 years in the frequency of extreme precipitation events over the Huaihe River basin in rainy season. There occurred an abrupt change around 2003， and the frequency of extreme precipitation events increased significantly at a significant level of 0.05 since 2003.
2012, 40(1):92-99.
Abstract:
The characteristics and forming, maintaining and dissipating mechanisms of a sustained sea heavy fog occurred over the Yellow Sea, Bohai Sea, and adjoining areas from 31 May to 5 June 2010 is analyzed by means of various data, including MTSAT1R satellite data, conventional surface and upper air observation data, FNL (objectively reanalyzed Final Analysis） data issued by NCEP and daily averaged sea surface temperature (SST) from NEARGOOS (NorthEast Asian Regional Global Ocean Observing System). The results indicate: the moisture in the lowlevel air was very abundant before the fog, and a transformed cold high pressure sustained stably over the Yellow Sea and Bohai Sea and provided a good background condition for the sustained sea fog, and then sea fog formed mainly in nighttime because of radiation cooling. During the fog, air temperature was just a little higher than SST, and subsidence inversion existed in the lowlevel air below 975 hPa. The development of cold temperature advection also contributed to the cooling of moist air in the lowlevel air, which played important roles in the development and sustaining of the sea fog. As air temperature rose again and the moisture dropped, relative humidity descended gradually and led the fog to disappear slowly.
The characteristics and forming, maintaining and dissipating mechanisms of a sustained sea heavy fog occurred over the Yellow Sea, Bohai Sea, and adjoining areas from 31 May to 5 June 2010 is analyzed by means of various data, including MTSAT1R satellite data, conventional surface and upper air observation data, FNL (objectively reanalyzed Final Analysis） data issued by NCEP and daily averaged sea surface temperature (SST) from NEARGOOS (NorthEast Asian Regional Global Ocean Observing System). The results indicate: the moisture in the lowlevel air was very abundant before the fog, and a transformed cold high pressure sustained stably over the Yellow Sea and Bohai Sea and provided a good background condition for the sustained sea fog, and then sea fog formed mainly in nighttime because of radiation cooling. During the fog, air temperature was just a little higher than SST, and subsidence inversion existed in the lowlevel air below 975 hPa. The development of cold temperature advection also contributed to the cooling of moist air in the lowlevel air, which played important roles in the development and sustaining of the sea fog. As air temperature rose again and the moisture dropped, relative humidity descended gradually and led the fog to disappear slowly.
2012, 40(1):100-106.
Abstract:
Based on the concept of the multiscale wavelet edge detection, an algorithm is presented to process the radar reflectivity data, so to identify convective cloud echoes effectively and retrieve convective precipitation. Taking a severe thunderstorm with heavy precipitations happened in Nanjing between 6 and 7 July 2009 as an example, a case study is conducted, focusing on the 180 minutes with relatively dense lightning flashes and severe precipitation. The convective cloud echo areas are then recognized by means of the multiscale wavelet edge detection algorithm with the radar reflectivity data from Longwang station every 6 minutes. The corresponding convective precipitation is inversed through ZI relation. The lightning flashes in the same 6 minutes are calculated, so the relation between convective precipitation and lightning can be analyzed. Results show that Rain Yields per flash (RPF) ranges from 7.47×106 to 4.46×107 kg, with average value being 1.72×107 kg; the nonlinear curve fitting equation of precipitation intensity and lightning frequency is established.
Based on the concept of the multiscale wavelet edge detection, an algorithm is presented to process the radar reflectivity data, so to identify convective cloud echoes effectively and retrieve convective precipitation. Taking a severe thunderstorm with heavy precipitations happened in Nanjing between 6 and 7 July 2009 as an example, a case study is conducted, focusing on the 180 minutes with relatively dense lightning flashes and severe precipitation. The convective cloud echo areas are then recognized by means of the multiscale wavelet edge detection algorithm with the radar reflectivity data from Longwang station every 6 minutes. The corresponding convective precipitation is inversed through ZI relation. The lightning flashes in the same 6 minutes are calculated, so the relation between convective precipitation and lightning can be analyzed. Results show that Rain Yields per flash (RPF) ranges from 7.47×106 to 4.46×107 kg, with average value being 1.72×107 kg; the nonlinear curve fitting equation of precipitation intensity and lightning frequency is established.
2012, 40(1):107-113.
Abstract:
A diagnostic analysis is made of a hail event happened in Ninglang in the northwestern Yunnan Province. The results indicate that the main objective conditions of this hail process include abundant moisture, instable stratification and strong vertical ascending motion. Before the process, the water vapor and dynamical forcing conditions were not favorable, except the unstable conditions. By analyzing the numerical prediction products before the hail process, the forecasting of major impact systems, water vapor, uplift motion, and instability conditions were conducted. The forecasting and warning of severe hail events can be well realized by analyzing the major influence systems, physical diagnostic products, including numerical forecast products, in combination with satellite images and radar echo data.
A diagnostic analysis is made of a hail event happened in Ninglang in the northwestern Yunnan Province. The results indicate that the main objective conditions of this hail process include abundant moisture, instable stratification and strong vertical ascending motion. Before the process, the water vapor and dynamical forcing conditions were not favorable, except the unstable conditions. By analyzing the numerical prediction products before the hail process, the forecasting of major impact systems, water vapor, uplift motion, and instability conditions were conducted. The forecasting and warning of severe hail events can be well realized by analyzing the major influence systems, physical diagnostic products, including numerical forecast products, in combination with satellite images and radar echo data.
2012, 40(1):114-120.
Abstract:
Soil moisture measurement was conducted at the meteorological station and in farm land respectively from 2006 to 2008, for contrasting soil moisture mearements from the two cases under the same climate background. The relationship of soil moisture in the two cases is analyzed by the statistic method. The results show that there has marked consistency in the soil moisture from the two cases and there is significantly positive correlation in four seasons；in spring, the rate of difference in soil moisture between station and farmland measurements is larger in rainy weather than that without rainfall; in summer, the soil moisture measurements from 0 cm to 30 cm between station and farmland have a good relationship, and the difference rate is from -4.8% to 2.1% under the low vegetation condition; in fall, the difference rate becomes less and ranges from -4.3% to -1.4% under the low vegetation condition; in winter, the difference rate is larger, especially from 0 cm to 10 cm, greater than 17%. The mathematical model is established for the period with good correlation at various levels.
Soil moisture measurement was conducted at the meteorological station and in farm land respectively from 2006 to 2008, for contrasting soil moisture mearements from the two cases under the same climate background. The relationship of soil moisture in the two cases is analyzed by the statistic method. The results show that there has marked consistency in the soil moisture from the two cases and there is significantly positive correlation in four seasons；in spring, the rate of difference in soil moisture between station and farmland measurements is larger in rainy weather than that without rainfall; in summer, the soil moisture measurements from 0 cm to 30 cm between station and farmland have a good relationship, and the difference rate is from -4.8% to 2.1% under the low vegetation condition; in fall, the difference rate becomes less and ranges from -4.3% to -1.4% under the low vegetation condition; in winter, the difference rate is larger, especially from 0 cm to 10 cm, greater than 17%. The mathematical model is established for the period with good correlation at various levels.
2012, 40(1):121-126.
Abstract:
By using the 40year meteorological data from 29 basic meteorological stations and the 10year phenological observation data of apple from 7 representative stations, in combination with the indexes of suitable meteorological conditions for apple growth and meteorological disaster indexes for apple, selecting such meteorological factors as weather condition, air temperature, relative humidity, and wind speed, a series of agrometeorological forecast products (including meteorological disaster forecasts, major farming activities, and meteorological conditions suitable for apple growth) are developed. These products are based on the comprehensive evaluation of agrometeorological resources management and disaster effects by using the basic agrometeorological theory and statistical methods, which play an active role in apple production management and disaster prevention and reduction. Some constructive suggestions and ideas to improve agrometeorological forecast service are presented.
By using the 40year meteorological data from 29 basic meteorological stations and the 10year phenological observation data of apple from 7 representative stations, in combination with the indexes of suitable meteorological conditions for apple growth and meteorological disaster indexes for apple, selecting such meteorological factors as weather condition, air temperature, relative humidity, and wind speed, a series of agrometeorological forecast products (including meteorological disaster forecasts, major farming activities, and meteorological conditions suitable for apple growth) are developed. These products are based on the comprehensive evaluation of agrometeorological resources management and disaster effects by using the basic agrometeorological theory and statistical methods, which play an active role in apple production management and disaster prevention and reduction. Some constructive suggestions and ideas to improve agrometeorological forecast service are presented.
2012, 40(1):127-131.
Abstract:
Natural clouds and fogs in the atmospheric environment are important factors which affect the precision of optically guided weapons. However, because of the nonreproducibility of natural clouds, it is hard to study the impact of clouds on the optically guided weapons. In order to assess the impact of natural clouds on the operation of optically guided weapons preferably, it is necessary to carry out the simulation of natural clouds in cloud chambers. Based on the brief introduction of artificial fog researches and the main features of a fog laboratory, the control of spray, catalyst release, temperature, humidity, airflow, and illumination in the process of artificial fog making is described in detail. The development trends of artificial fog researches in the future are also discussed.
Natural clouds and fogs in the atmospheric environment are important factors which affect the precision of optically guided weapons. However, because of the nonreproducibility of natural clouds, it is hard to study the impact of clouds on the optically guided weapons. In order to assess the impact of natural clouds on the operation of optically guided weapons preferably, it is necessary to carry out the simulation of natural clouds in cloud chambers. Based on the brief introduction of artificial fog researches and the main features of a fog laboratory, the control of spray, catalyst release, temperature, humidity, airflow, and illumination in the process of artificial fog making is described in detail. The development trends of artificial fog researches in the future are also discussed.
2012, 40(1):132-136.
Abstract:
The number of thunderstorm days is an important parameter for studying the regularities of lightning activities. According to the mathematical and statistic analysis of thunderstorm data based on the manual observation from 1951 to 2009 and the measurements from the lightning location system from 1999 to 2008， an anaysis is made of the characteristics of the number of thunderstorm days and the ground flash density. It is concluded that the number of thunderstorm days from manual observation is much less than that measured by the lightning location system; both manual observation and lightning location system have some limitations： they cannot reflect objectively the regularities of lightning activities in different regions because of the methodology and sensitivity of the sounding devices. The effective thunderstorm parameters in various regions in Chongqing are obtained， which provides an academic basis for the evaluation of lightning disaster risk assessment and lightning protection design.
The number of thunderstorm days is an important parameter for studying the regularities of lightning activities. According to the mathematical and statistic analysis of thunderstorm data based on the manual observation from 1951 to 2009 and the measurements from the lightning location system from 1999 to 2008， an anaysis is made of the characteristics of the number of thunderstorm days and the ground flash density. It is concluded that the number of thunderstorm days from manual observation is much less than that measured by the lightning location system; both manual observation and lightning location system have some limitations： they cannot reflect objectively the regularities of lightning activities in different regions because of the methodology and sensitivity of the sounding devices. The effective thunderstorm parameters in various regions in Chongqing are obtained， which provides an academic basis for the evaluation of lightning disaster risk assessment and lightning protection design.
2012, 40(1):137-140.
Abstract:
The fitting formulas recommended by IEEE and the related departments in China are studied with the least square method， by means of the monitoring data of the lightning location system over Zhejiang in 2007 and 2008， as well as the curve fitting toolbox in Matlab. It is found that the former fits better than the latter. Through analyzing the relative errors of the calculated results of the IEEE formula and the observed values， it is found that the cumulative frequency of positive lightning current amplitude is smaller than 10%; but the cumulative frequency of negative lightning current amplitude is big in the range of -1 kA to -300 kA， with the maximum being about 38%. In response to these circumstances， the approximate function of the relative error curve fitted by mathematic software is presented， and the original cumulative frequency formula is corrected. The relative errors are significantly reduced. The application range of the formula can be enlarged from original （2 kA， 200 kA） to （1 kA， 270 kA） for positive lightning and （-300 kA， -1 kA） for negative lightning.
The fitting formulas recommended by IEEE and the related departments in China are studied with the least square method， by means of the monitoring data of the lightning location system over Zhejiang in 2007 and 2008， as well as the curve fitting toolbox in Matlab. It is found that the former fits better than the latter. Through analyzing the relative errors of the calculated results of the IEEE formula and the observed values， it is found that the cumulative frequency of positive lightning current amplitude is smaller than 10%; but the cumulative frequency of negative lightning current amplitude is big in the range of -1 kA to -300 kA， with the maximum being about 38%. In response to these circumstances， the approximate function of the relative error curve fitted by mathematic software is presented， and the original cumulative frequency formula is corrected. The relative errors are significantly reduced. The application range of the formula can be enlarged from original （2 kA， 200 kA） to （1 kA， 270 kA） for positive lightning and （-300 kA， -1 kA） for negative lightning.
2012, 40(1):141-143.
Abstract:
It is necessary for the construction and acceptance of a lightning protection project for weakcurrent equipment rooms to have a comprehensive， practical and the applicable judgment method to decide whether the capability of a lightning protection system meets the requirements. Taking a lightning protection project for a weakcurrent equipment room as an example， the key parameters that influence the reliability of lighting protection for weak current equipment rooms are analyzed and obtained. The parameters include the spatial shield efficiency， transmission cable shield efficiency， terminal maximum pulse voltage limits， inductive voltage at the maximum split ring in equipment room cabling， pressurebalancing and discharging capability. The appraisal and computation are conducted on these key parameters， and a parameter list of lightning protection efficiency determination for weak current equipment rooms is presented.
It is necessary for the construction and acceptance of a lightning protection project for weakcurrent equipment rooms to have a comprehensive， practical and the applicable judgment method to decide whether the capability of a lightning protection system meets the requirements. Taking a lightning protection project for a weakcurrent equipment room as an example， the key parameters that influence the reliability of lighting protection for weak current equipment rooms are analyzed and obtained. The parameters include the spatial shield efficiency， transmission cable shield efficiency， terminal maximum pulse voltage limits， inductive voltage at the maximum split ring in equipment room cabling， pressurebalancing and discharging capability. The appraisal and computation are conducted on these key parameters， and a parameter list of lightning protection efficiency determination for weak current equipment rooms is presented.
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.