Volume 41,Issue 4,2013 Table of Contents
2013, 41(4):597-602.
Abstract:
A snow depth sensor based on the the phase method laser rangefinding is described from aspects of the sensor measurement principle, observation method, and data processing algorithm, which participated in the snow depth contrast observational experiments between such stations as Tonghe (Heilongjiang River), Altai (Xinjiang), etc., organized by the China Meteorological Administation in 2010 and 2011 The measurements are compared with the ultrasonic sensor and artificial measured snow depth data. The results indicates that this laser snow depth sensor can adapt to winter cold and Blizzard weather conditions well, can monitor snow surface changes continuously, automatically, and accurately; compared to the ultrasonic snow deep sensor, the laser snow depth sensor measurements are more stable and closer to artificial observation; the average difference between the laser snow depth sensor and artificial measurement snow deep results is about 1 cm, and the measurement precision reached the requirements of “Ground Meteorological Observation Specification”.
A snow depth sensor based on the the phase method laser rangefinding is described from aspects of the sensor measurement principle, observation method, and data processing algorithm, which participated in the snow depth contrast observational experiments between such stations as Tonghe (Heilongjiang River), Altai (Xinjiang), etc., organized by the China Meteorological Administation in 2010 and 2011 The measurements are compared with the ultrasonic sensor and artificial measured snow depth data. The results indicates that this laser snow depth sensor can adapt to winter cold and Blizzard weather conditions well, can monitor snow surface changes continuously, automatically, and accurately; compared to the ultrasonic snow deep sensor, the laser snow depth sensor measurements are more stable and closer to artificial observation; the average difference between the laser snow depth sensor and artificial measurement snow deep results is about 1 cm, and the measurement precision reached the requirements of “Ground Meteorological Observation Specification”.
2013, 41(4):603-607.
Abstract:
Two problems affect the quality of the small raindrop measurement: the signals of small raindrops at the receiver of optical disdrometer are very weak; it is difficult to detect signals from a very noisy background. Based on the digital lock in amplifier (DLIA) technique of weak signal detection principles, a digital lock in amplifier with OMAP3530’s DSP Core is constructed to solve the problems. The system is not only simple in structure, but also easy to implement. It can overcome zero drift and none linear in analog devices. Computer simulation results show that it can amplify weak signals constantly, inhibit the noise amplification of other frequency, and increase Signal to Noise Ratio (SNR). It can improve the detection of small drops in optical disdrometer effectively.
Two problems affect the quality of the small raindrop measurement: the signals of small raindrops at the receiver of optical disdrometer are very weak; it is difficult to detect signals from a very noisy background. Based on the digital lock in amplifier (DLIA) technique of weak signal detection principles, a digital lock in amplifier with OMAP3530’s DSP Core is constructed to solve the problems. The system is not only simple in structure, but also easy to implement. It can overcome zero drift and none linear in analog devices. Computer simulation results show that it can amplify weak signals constantly, inhibit the noise amplification of other frequency, and increase Signal to Noise Ratio (SNR). It can improve the detection of small drops in optical disdrometer effectively.
2013, 41(4):608-613.
Abstract:
Phase noise is a very important index for radar transmitters and receivers，which can directly indicate the coherence of Doppler radar． In order to understand the physical significance of phase noise, a method for phase noise fault examination is summarized, which can be used to guide weather radar maintenance. The physical significance of phase noise is analyzed, and some disturbance factors from radar transmitters and receivers are studied according to the phase noise calibration principles and test methods. The disturbance factors are carefully discussed and tested to propose a method for phase noise abnormality solution. The phase noise fault examination and analysis for CINRAD/SA weather radar at Heyuan of Guangdong proved that the method is effective.
Phase noise is a very important index for radar transmitters and receivers，which can directly indicate the coherence of Doppler radar． In order to understand the physical significance of phase noise, a method for phase noise fault examination is summarized, which can be used to guide weather radar maintenance. The physical significance of phase noise is analyzed, and some disturbance factors from radar transmitters and receivers are studied according to the phase noise calibration principles and test methods. The disturbance factors are carefully discussed and tested to propose a method for phase noise abnormality solution. The phase noise fault examination and analysis for CINRAD/SA weather radar at Heyuan of Guangdong proved that the method is effective.
2013, 41(4):614-619.
Abstract:
According to the operating principles of the new generation weather radar receiver system and the measuring method of key parameters of the receiving system characteristic curve, in combination with the abnormality analysis of CINRAD/CC weather radar system abnormal characteristic curve faults, the method for diagnosing and analyzing the abnormal faults of the new generation weather radar receiver is summed up, which is used in the troubleshooting practice of the new generation weather radar receiver characteristic curve faults. The results show that the diagnostic procedure and troubleshooting method are not only fast and effective, but also normative and stable, can be used as reference for the maintenance personnel in the troubleshooting of various weather radar receiver characteristic curve faults.
According to the operating principles of the new generation weather radar receiver system and the measuring method of key parameters of the receiving system characteristic curve, in combination with the abnormality analysis of CINRAD/CC weather radar system abnormal characteristic curve faults, the method for diagnosing and analyzing the abnormal faults of the new generation weather radar receiver is summed up, which is used in the troubleshooting practice of the new generation weather radar receiver characteristic curve faults. The results show that the diagnostic procedure and troubleshooting method are not only fast and effective, but also normative and stable, can be used as reference for the maintenance personnel in the troubleshooting of various weather radar receiver characteristic curve faults.
2013, 41(4):620-625.
Abstract:
The working condition of the filament power control circuit in CINRAD/SA Radar in is described in detail and the characteristics of the pulse width modulator control circuit SG1525A are analyzed. The debugging is conducted on the key waveforms which control the chopper pulse width modulation circuit and the oscillator control circuit, as well as the filament power supply output voltage and filament voltage and current protection step by step. The procedures and techniques of filament power fault diagnosis and troubleshooting are summed up based on actual experiences, to provide a reference for the troubleshooting of radar filament power supply failure.
The working condition of the filament power control circuit in CINRAD/SA Radar in is described in detail and the characteristics of the pulse width modulator control circuit SG1525A are analyzed. The debugging is conducted on the key waveforms which control the chopper pulse width modulation circuit and the oscillator control circuit, as well as the filament power supply output voltage and filament voltage and current protection step by step. The procedures and techniques of filament power fault diagnosis and troubleshooting are summed up based on actual experiences, to provide a reference for the troubleshooting of radar filament power supply failure.
2013, 41(4):626-629.
Abstract:
In order to avoid the effect of CINRAD/SA Weather Radar at Huangshan Station on Parsivel spectrometer valid observations, the reasons for the effect and the processing method are discussed. A steel mesh is placed in the appropriate location between radar and Parsivel spectrometer, based on the property of metal, which can absorb electromagnetic waves. The results show that the steel mesh can completely shield the effect of the radar on Parsivel spectrometer and the reliability of observational data can be protected well.
In order to avoid the effect of CINRAD/SA Weather Radar at Huangshan Station on Parsivel spectrometer valid observations, the reasons for the effect and the processing method are discussed. A steel mesh is placed in the appropriate location between radar and Parsivel spectrometer, based on the property of metal, which can absorb electromagnetic waves. The results show that the steel mesh can completely shield the effect of the radar on Parsivel spectrometer and the reliability of observational data can be protected well.
2013, 41(4):630-634.
Abstract:
The construction of the Atmospheric Observing System Operations and Monitoring system improved the capacity of operational supporting on the detection equipment of the integrated meteorological observation network. As a beneficial supplement to the monitoring system, a GIS application platform is constructed, which is oriented to meteorological observing based on ArcGIS Engine technology. The method of meteorological observing equipment monitoring is described emphatically, and several key issues about meteorological equipment monitoring based on C/S structure, such as data acquisition, data handling, map update, etc., are discussed. The system combines data retrieval, map display, equipment monitoring, statistic and analysis, and product release together, as well as the management of the observing station network. It realizes diversification, informatization, visualization, professionalization, and productization of meteorological equipment monitoring.
The construction of the Atmospheric Observing System Operations and Monitoring system improved the capacity of operational supporting on the detection equipment of the integrated meteorological observation network. As a beneficial supplement to the monitoring system, a GIS application platform is constructed, which is oriented to meteorological observing based on ArcGIS Engine technology. The method of meteorological observing equipment monitoring is described emphatically, and several key issues about meteorological equipment monitoring based on C/S structure, such as data acquisition, data handling, map update, etc., are discussed. The system combines data retrieval, map display, equipment monitoring, statistic and analysis, and product release together, as well as the management of the observing station network. It realizes diversification, informatization, visualization, professionalization, and productization of meteorological equipment monitoring.
2013, 41(4):635-638.
Abstract:
Hydrogen filling and releasing of sounding balloons are the important parts of upper air observation. The radiosonde tracking by radar, reception of radiosonde signals and data processing are automatic presently, except for hydrogen filling and balloon releasing. Hydrogen filling is to some extent danger, and balloon releasing occupies an observer. Based on the analysis of steps of hydrogen filling and balloon releasing, the design of balloon releasing machine and the means to make better use of it in practice are described, which sets a stage for the automation of the upper air observation system.
Hydrogen filling and releasing of sounding balloons are the important parts of upper air observation. The radiosonde tracking by radar, reception of radiosonde signals and data processing are automatic presently, except for hydrogen filling and balloon releasing. Hydrogen filling is to some extent danger, and balloon releasing occupies an observer. Based on the analysis of steps of hydrogen filling and balloon releasing, the design of balloon releasing machine and the means to make better use of it in practice are described, which sets a stage for the automation of the upper air observation system.
2013, 41(4):639-643.
Abstract:
The observer satisfaction model of AWS (automatic weather station) measurement is set up by using QFD (Quality Function Deployment), which is an evaluation tool for AWS quality research. The satisfaction degree of observers for AWS is expanded into some details that concern observers through a two stage quality house. The evaluation helps not only AWS designers, and technicians directly know about AWS operation status, but also understand its weak points so to find solutions.
The observer satisfaction model of AWS (automatic weather station) measurement is set up by using QFD (Quality Function Deployment), which is an evaluation tool for AWS quality research. The satisfaction degree of observers for AWS is expanded into some details that concern observers through a two stage quality house. The evaluation helps not only AWS designers, and technicians directly know about AWS operation status, but also understand its weak points so to find solutions.
2013, 41(4):644-647.
Abstract:
The meteorological telecommunication system is the hub of transmitting national and international data, in order to grasp the situation of data transmission in the meteorological telecommunication 〖JP〗system, manage the data effectively, optimize and combine the operational service processes, according to the characteristics of the data, a multi dimensional model is constructed with the data of the telecommunication system, and a solution to long time series data is proposed, which uses the SQL Server Analysis Service to launch a pilot run with the data in the real operational environment, and implement the OLAP application, and verify the advantages of the multi dimensional model in data analysis and display.
The meteorological telecommunication system is the hub of transmitting national and international data, in order to grasp the situation of data transmission in the meteorological telecommunication 〖JP〗system, manage the data effectively, optimize and combine the operational service processes, according to the characteristics of the data, a multi dimensional model is constructed with the data of the telecommunication system, and a solution to long time series data is proposed, which uses the SQL Server Analysis Service to launch a pilot run with the data in the real operational environment, and implement the OLAP application, and verify the advantages of the multi dimensional model in data analysis and display.
2013, 41(4):648-652.
Abstract:
The main technology and some problems during the designing and developing of a meteorological data analyzing and service product making software for the Kelamayi Meteorological Service. According to the designing principle of being simple, stable, reliable, and maintainable, this software adopts plug in technology and has the functions of displaying the images in the MICAPS data format and auto weather station data solo or overlay, and voice and text warning automatically, inputting the forecasting results into database, generating Word and Excel documents with different contents and comments and so on.
The main technology and some problems during the designing and developing of a meteorological data analyzing and service product making software for the Kelamayi Meteorological Service. According to the designing principle of being simple, stable, reliable, and maintainable, this software adopts plug in technology and has the functions of displaying the images in the MICAPS data format and auto weather station data solo or overlay, and voice and text warning automatically, inputting the forecasting results into database, generating Word and Excel documents with different contents and comments and so on.
2013, 41(4):653-658.
Abstract:
With the social and economic development, the public meteorological service with detailed meteorological information are needed more and more. Through exploring the requirements of charts for TV meteorological programs, a method to generate meteorological charts rapidly and the design ideas are introduced. The meteorological data are processed and analyzed with VB in the Windows environment, and then Matlab or Photoshop in ActiveX is used to process these data secondly. The automation degree and picture quality of the charts are improved by using the mixed programming technology. More meteorological data and analysis results can be visualized rapidly and more effective information are provided to the public by media in time.
With the social and economic development, the public meteorological service with detailed meteorological information are needed more and more. Through exploring the requirements of charts for TV meteorological programs, a method to generate meteorological charts rapidly and the design ideas are introduced. The meteorological data are processed and analyzed with VB in the Windows environment, and then Matlab or Photoshop in ActiveX is used to process these data secondly. The automation degree and picture quality of the charts are improved by using the mixed programming technology. More meteorological data and analysis results can be visualized rapidly and more effective information are provided to the public by media in time.
2013, 41(4):659-663.
Abstract:
Taking the HD virtual studio construction project of Huafeng group as an example, several problems and difficulties that need to be resolved with priority in HD virtual studio technology application are discussed in the aspects of system construction, system calibration, and weather forecast services. According to the requirements of weather television program making, six vital technical problems in the entire process of virtual studio system design and program making are solved, including the audio system delay calculation method, green box construction and lighting layout, chroma key calibration, camera positioning, tracking calibration, and meteorological data transferring and conversion. The success of this system practice is a good example to apply and popularize virtual studio technologies in weather television industry in China.
Taking the HD virtual studio construction project of Huafeng group as an example, several problems and difficulties that need to be resolved with priority in HD virtual studio technology application are discussed in the aspects of system construction, system calibration, and weather forecast services. According to the requirements of weather television program making, six vital technical problems in the entire process of virtual studio system design and program making are solved, including the audio system delay calculation method, green box construction and lighting layout, chroma key calibration, camera positioning, tracking calibration, and meteorological data transferring and conversion. The success of this system practice is a good example to apply and popularize virtual studio technologies in weather television industry in China.
2013, 41(4):664-669.
Abstract:
Typhoon Morakot (0908) caused severe damage. In order to explore the underlying reasons, the phenomenon that the intensity of the typhoon always remained around 960 hPa and did not reduce when it passed over the island of Taiwan is studied from both observational and numerical simulation results, by using the NCEP/NCAR1°×1°data and WRF numerical model. The observational analysis shows that the no reduction of Typhoon Morakot’s intensity was closely related to the interaction between Morakot and Goni (0907), which was in its southwest direction, and some physical quantities from Typhoon Goni were continuously transported into Morakot, such as the inputting of water vapor were mainly from 950 to 850 hPa, but rarely above 600 hPa. The transmission of vertical velocity existed in the whole layer, extending from 1000 hPa to 300 hPa. The positive vorticity (negative divergence) was transferred at the lower levels, and the negative vorticity (positive divergence) at the upper levels. Using the WRF numerical model for each control and sensitivity experiment in which Typhoon Goni was filtered, the results show that vorticity, moisture flux, divergence, and other physical quantities from Typhoon Goni were transported and involved in Typhoon Morakot, and thus they gave positive contribution to the maintenance and no reduction of Typhoon Morakot intensity when it passed over the island of Taiwan.
Typhoon Morakot (0908) caused severe damage. In order to explore the underlying reasons, the phenomenon that the intensity of the typhoon always remained around 960 hPa and did not reduce when it passed over the island of Taiwan is studied from both observational and numerical simulation results, by using the NCEP/NCAR1°×1°data and WRF numerical model. The observational analysis shows that the no reduction of Typhoon Morakot’s intensity was closely related to the interaction between Morakot and Goni (0907), which was in its southwest direction, and some physical quantities from Typhoon Goni were continuously transported into Morakot, such as the inputting of water vapor were mainly from 950 to 850 hPa, but rarely above 600 hPa. The transmission of vertical velocity existed in the whole layer, extending from 1000 hPa to 300 hPa. The positive vorticity (negative divergence) was transferred at the lower levels, and the negative vorticity (positive divergence) at the upper levels. Using the WRF numerical model for each control and sensitivity experiment in which Typhoon Goni was filtered, the results show that vorticity, moisture flux, divergence, and other physical quantities from Typhoon Goni were transported and involved in Typhoon Morakot, and thus they gave positive contribution to the maintenance and no reduction of Typhoon Morakot intensity when it passed over the island of Taiwan.
2013, 41(4):670-681.
Abstract:
The relationship between Tibet plateau heat sources in early spring and sea surface temperature (SST) in the prior winter is analyzed and explored, based on the data of NCEP/NCAR monthly reanalysis from 1951 to 2007, and NOAA’s extended reconstruction SST data (ERSST.v3b). The methods used include standardized index, abnormal year synthesis, and statistical analysis. The results show that there are two areas in the North Pacific Ocean, in which SST in previous winter has remarkable correlation with the heat sources on the plateau in early spring: Region A located in the Eastern North Pacific with the positive relation, and Region B located in the Western North Pacific with negative relation. Meanwhile, the persistent correlation between SST in previous winter and heat sources in the plateau in March is analyzed; it was found that the method using the variation of SST in the prior winter in both Region A and B has shown some skill in predicting Tibet plateau heat sources in spring. The abnormal synthesis reveals that the abnormal characteristics of atmospheric heat sources and the vertical structure of the wind fields correspond to the abnormal years of previous winter sea temperature in strong signal areas. The further study indicates that the characteristics of the late summer 500 hPa height field pattern and its water vapor transport vectors are related with previous winter SST in Yangtze rainy years.
The relationship between Tibet plateau heat sources in early spring and sea surface temperature (SST) in the prior winter is analyzed and explored, based on the data of NCEP/NCAR monthly reanalysis from 1951 to 2007, and NOAA’s extended reconstruction SST data (ERSST.v3b). The methods used include standardized index, abnormal year synthesis, and statistical analysis. The results show that there are two areas in the North Pacific Ocean, in which SST in previous winter has remarkable correlation with the heat sources on the plateau in early spring: Region A located in the Eastern North Pacific with the positive relation, and Region B located in the Western North Pacific with negative relation. Meanwhile, the persistent correlation between SST in previous winter and heat sources in the plateau in March is analyzed; it was found that the method using the variation of SST in the prior winter in both Region A and B has shown some skill in predicting Tibet plateau heat sources in spring. The abnormal synthesis reveals that the abnormal characteristics of atmospheric heat sources and the vertical structure of the wind fields correspond to the abnormal years of previous winter sea temperature in strong signal areas. The further study indicates that the characteristics of the late summer 500 hPa height field pattern and its water vapor transport vectors are related with previous winter SST in Yangtze rainy years.
2013, 41(4):682-689.
Abstract:
Using the ARPS/ADAS cloud analysis system, the radar reflectivity factor is introduced into the initial field of the mesoscale numerical model. A severe hailstorm occurred in Beijing on 23 June 2008 is simulated. The study indicates that the hydrometeors and temperature field in the initiate field are improved significantly with the introduction of the radar reflectivity, and it makes the initial field closer to the actual atmosphere. Compared with the tests without cloud analysis, the simulations with cloud analysis are better in the formation position, intensity, and motion paths of hail clouds, especially for the simulation results within three hours. With the cloud analysis, precipitation and hail happen an hour earlier, and precipitation and the hail peak also occur earlier; the spin up time was reduced with the introduction of radar reflectivity information.
Using the ARPS/ADAS cloud analysis system, the radar reflectivity factor is introduced into the initial field of the mesoscale numerical model. A severe hailstorm occurred in Beijing on 23 June 2008 is simulated. The study indicates that the hydrometeors and temperature field in the initiate field are improved significantly with the introduction of the radar reflectivity, and it makes the initial field closer to the actual atmosphere. Compared with the tests without cloud analysis, the simulations with cloud analysis are better in the formation position, intensity, and motion paths of hail clouds, especially for the simulation results within three hours. With the cloud analysis, precipitation and hail happen an hour earlier, and precipitation and the hail peak also occur earlier; the spin up time was reduced with the introduction of radar reflectivity information.
2013, 41(4):690-695.
Abstract:
A monthly early rainy season precipitation prediction model is devised by means of the partial least squares regression (PLS) method. The input factors of the model are selected from a large quantity of preceding period high correlation factors by using the empirical orthogonal function (EOF) method. The model converts the prediction of multi site monthly precipitation to that of the principal component of that field. According to the approximate invariability of eigenvectors of climate fields, the return computation is conducted to get the monthly precipitation forecasts of more than one site, together with the principal component predicted by the PLS model. A 6 year independent sample test is carried out on the monthly early rainy season precipitation prediction for 37 basic stations in Guangxi. The results show that the model has good forecasting ability.
A monthly early rainy season precipitation prediction model is devised by means of the partial least squares regression (PLS) method. The input factors of the model are selected from a large quantity of preceding period high correlation factors by using the empirical orthogonal function (EOF) method. The model converts the prediction of multi site monthly precipitation to that of the principal component of that field. According to the approximate invariability of eigenvectors of climate fields, the return computation is conducted to get the monthly precipitation forecasts of more than one site, together with the principal component predicted by the PLS model. A 6 year independent sample test is carried out on the monthly early rainy season precipitation prediction for 37 basic stations in Guangxi. The results show that the model has good forecasting ability.
2013, 41(4):696-702.
Abstract:
Two coastal heavy rain events occurred in 4-5 and 21-22 August 2010 were caused by the subtropical high. For several kinds of numerical products that are used widely, verification is conducted mainly from the aspects of circulation situation, influencing systems, and precipitation elements. The results show that these numerical products have certain prediction capability for heavy rainfall quantitatively, but predicted rainfall levels are generally smaller, and the prediction of the strong precipitation center is poor in stability; the position forecasts of EC and T639 models are more accurate, but the intensity forecasts are smaller than the actual situation. There are certain differences between numerical models and the actual situation in the position and intensity of the weather systems producing the heavy rainfall. As for the West Pacific subtropical high, the 72 h forecast of the T639 model is weaker than the actual storm, and the stability of EC model is higher, but there is certain deviation in upper trough and shear line forecasts. In torrential rain forecasting, it is necessary, on the basis of numerical forecast products, to combine strong convective products with such auxiliary tools as intensive observation data, physical fields, similar examples, experienced empirical extrapolation, etc., to improve the forecast accuracy of heavy rain forecasts.
Two coastal heavy rain events occurred in 4-5 and 21-22 August 2010 were caused by the subtropical high. For several kinds of numerical products that are used widely, verification is conducted mainly from the aspects of circulation situation, influencing systems, and precipitation elements. The results show that these numerical products have certain prediction capability for heavy rainfall quantitatively, but predicted rainfall levels are generally smaller, and the prediction of the strong precipitation center is poor in stability; the position forecasts of EC and T639 models are more accurate, but the intensity forecasts are smaller than the actual situation. There are certain differences between numerical models and the actual situation in the position and intensity of the weather systems producing the heavy rainfall. As for the West Pacific subtropical high, the 72 h forecast of the T639 model is weaker than the actual storm, and the stability of EC model is higher, but there is certain deviation in upper trough and shear line forecasts. In torrential rain forecasting, it is necessary, on the basis of numerical forecast products, to combine strong convective products with such auxiliary tools as intensive observation data, physical fields, similar examples, experienced empirical extrapolation, etc., to improve the forecast accuracy of heavy rain forecasts.
2013, 41(4):703-712.
Abstract:
Using the ground based weather phenomena (fog) observations data of 76 stations over Shaanxi Province, and the monthly re analyzed NCEP/NCAR reanalysis dataset from 1960 to 2010, by menas of the EOF, wavelet, and regression analysis methods, the spatial temporal change characteristics of Shaanxi fogs and associated atmospheric circulation abnormity in the fog prone season are studied. The results show that: (1) Shaanxi fogs have obviously regional distributional feature, with three high and low frequency centers of fog days; rivers have significant influence on fog distribution, but it is not the main cause. (2) The average number of fog days reaches the peak from the middle and late 1980s to 1990s; the number of autumn fog days accounts more than 665% of fog days for the whole year. (3) The SEOF analysis shows that the number of fog days differs from one place to another. From August to October, fogs mainly appear in the north of Guanzhong, reaching the peak in September, while from October to December in the south of Shaanxi and in Guanzhong, reaching the peak in November. (4) The inter annual variability of Shaanxi fog mainly includes two modals: EOF1 and EOF2 (5) The circulation anomalies are associated to EOF1, which shows that SLP and 500 hPa geopotential heights over the land at middle latitudes in East Asia are abnormally higher. Shaanxi lies near the center of anticyclonic circulation over the 850 hPa average wind field, so when the anticyclonic anomalous circulation is in the west north and the northerly abnormal component is stronger, and the water vapor transport from the sea is in the south, fogs in Shaanxi are relatively rare in the north, and abundant in the central and southern Shaanxi.
Using the ground based weather phenomena (fog) observations data of 76 stations over Shaanxi Province, and the monthly re analyzed NCEP/NCAR reanalysis dataset from 1960 to 2010, by menas of the EOF, wavelet, and regression analysis methods, the spatial temporal change characteristics of Shaanxi fogs and associated atmospheric circulation abnormity in the fog prone season are studied. The results show that: (1) Shaanxi fogs have obviously regional distributional feature, with three high and low frequency centers of fog days; rivers have significant influence on fog distribution, but it is not the main cause. (2) The average number of fog days reaches the peak from the middle and late 1980s to 1990s; the number of autumn fog days accounts more than 665% of fog days for the whole year. (3) The SEOF analysis shows that the number of fog days differs from one place to another. From August to October, fogs mainly appear in the north of Guanzhong, reaching the peak in September, while from October to December in the south of Shaanxi and in Guanzhong, reaching the peak in November. (4) The inter annual variability of Shaanxi fog mainly includes two modals: EOF1 and EOF2 (5) The circulation anomalies are associated to EOF1, which shows that SLP and 500 hPa geopotential heights over the land at middle latitudes in East Asia are abnormally higher. Shaanxi lies near the center of anticyclonic circulation over the 850 hPa average wind field, so when the anticyclonic anomalous circulation is in the west north and the northerly abnormal component is stronger, and the water vapor transport from the sea is in the south, fogs in Shaanxi are relatively rare in the north, and abundant in the central and southern Shaanxi.
2013, 41(4):713-719.
Abstract:
The linear regression method is used to analyze the climatic trends in annual and seasonal mean temperatures observed at the Nanyue Mountain Observatory (2730°N, 11270°E, 1266 m ASL) from 1953 to 2011 Also the non parametric Mann Kendall (MK) test and running average 〖WTBX〗t〖WTBZ〗 test are performed to check the abrupt changes. Using a variety of analytical methods, the temperature variation regularity in more than half a century in Nanyue Mountain in the troposphere near the bottom of the atmosphere is obtained. The differences in temperature variation between Nanyue mountain and Low elevation areas (Hengshan and Hengyang) and the impaction of urbanization are analyzed. The results indicate that the annual mean daily averaged, maximum and minimum temperatures present significant upward trends in the past 58 years, with the increasing being 10, 08, and 11 ℃ per one year, respectively, and the little surrounding environment change and human activities influence. Mean temperature and minimum temperatures present increasing trends obviously in all seasons, except for an insignificant decreasing trend in summer related to daily maximum temperature. The annual mean daily and minimum temperatures changed suddenly in 1996 The daily maximum temperatures present positive anomalies in most of the period. Urbanization had certain positive contribution to the local temperature rising; the observing environment had a major influence on temperature variations in summer.
The linear regression method is used to analyze the climatic trends in annual and seasonal mean temperatures observed at the Nanyue Mountain Observatory (2730°N, 11270°E, 1266 m ASL) from 1953 to 2011 Also the non parametric Mann Kendall (MK) test and running average 〖WTBX〗t〖WTBZ〗 test are performed to check the abrupt changes. Using a variety of analytical methods, the temperature variation regularity in more than half a century in Nanyue Mountain in the troposphere near the bottom of the atmosphere is obtained. The differences in temperature variation between Nanyue mountain and Low elevation areas (Hengshan and Hengyang) and the impaction of urbanization are analyzed. The results indicate that the annual mean daily averaged, maximum and minimum temperatures present significant upward trends in the past 58 years, with the increasing being 10, 08, and 11 ℃ per one year, respectively, and the little surrounding environment change and human activities influence. Mean temperature and minimum temperatures present increasing trends obviously in all seasons, except for an insignificant decreasing trend in summer related to daily maximum temperature. The annual mean daily and minimum temperatures changed suddenly in 1996 The daily maximum temperatures present positive anomalies in most of the period. Urbanization had certain positive contribution to the local temperature rising; the observing environment had a major influence on temperature variations in summer.
2013, 41(4):720-725.
Abstract:
The spatial patterns of sea surface strong wind (beyond Beaufort wind scale 6) in the China Sea are analyzed through adopting the high resolution Cross Calibrated Multi Platform (CCMP) wind data. According to the definitions of the China costal sea areas by the National Meteorological Center (NMC), the seasonal variations of the strong wind days in these 18 sea areas are also examined. The analysis results show that the highest values of strong wind days and speed are centering around the Bashi Channel, Taiwan Strait and the Northeast part of South China Sea (SCS). The seasonal variations in coastal China seas can obviously reflect that the East Asia monsoon is strong in winter and weak in summer. In winter, the centers of strong wind days and speed always locate in the northeast part of ECS, Bashi Channel, Taiwan Strait, and the northeast part of SCS, and the maximum days and strongest speed appear in December; while in summer, these centers disappear. The center locating in the southwest part of SCS disappears from April. However, the seasonal changes of the strong wind days in these eighteen sea areas are different. Those in the middle and south parts of SCS have two peaks: one occurring from December to January, and the other from July to August. While in other thirteen sea areas, the high value of the strong wind days appears from December to January and the low one from June to July.
The spatial patterns of sea surface strong wind (beyond Beaufort wind scale 6) in the China Sea are analyzed through adopting the high resolution Cross Calibrated Multi Platform (CCMP) wind data. According to the definitions of the China costal sea areas by the National Meteorological Center (NMC), the seasonal variations of the strong wind days in these 18 sea areas are also examined. The analysis results show that the highest values of strong wind days and speed are centering around the Bashi Channel, Taiwan Strait and the Northeast part of South China Sea (SCS). The seasonal variations in coastal China seas can obviously reflect that the East Asia monsoon is strong in winter and weak in summer. In winter, the centers of strong wind days and speed always locate in the northeast part of ECS, Bashi Channel, Taiwan Strait, and the northeast part of SCS, and the maximum days and strongest speed appear in December; while in summer, these centers disappear. The center locating in the southwest part of SCS disappears from April. However, the seasonal changes of the strong wind days in these eighteen sea areas are different. Those in the middle and south parts of SCS have two peaks: one occurring from December to January, and the other from July to August. While in other thirteen sea areas, the high value of the strong wind days appears from December to January and the low one from June to July.
2013, 41(4):726-735.
Abstract:
The heavy rainfall process occurred on 30 July 1988 around the southeastern coast of Zhejiang Province is investigated by 05° NCEP Climate Forecast System Reanalysis data. It is found that the heavy rainfall was mainly caused by the merging of two low level east wind perturbations from south and north, respectively, and its interaction with upper level jets. The south and north branches of the easterly wave originated from the abrupt westerly, southerly evolution of the subtropical anticyclone, and the development of convective perturbations triggered by the typhoon inverted trough, respectively. The east west oriented upper level jet was formed under the combined forcing of the upper level cold vortex and the Huabei anticyclone system. The upper level jet possessed an obvious downward transmission feature in momentum, which would enhance the easterly wind component at middle troposphere and form a deep easterly wave system. The convective available potential energy (CAPE) in the heavy rainfall event of 30 July 1988 was mainly caused by the advection of air mass on the sea. The convergence in low pressure converted trough could accumulate water content in air and form a deep level with high equivalent potential temperature. This high equivalent potential temperature level may moved westward along with the easterly wave system and concentrate CAPE to convection development. There existed cold advection at the upper troposphere which could make the value of CAPE maintain steady during the westerly moving of easterly wave. The potential possibility of heavy rainfall caused by moving easterly wave could not be predicted by the single point sounding on the ground. The storm relative helicity matched with the easterly wave system very well and from it the emerging process of the south and north branches of east wind perturbations could be reflected clearly. The moving speed of the storm relative helicity was a little faster than that of the easterly wave system and vertical vorticity, and therefore the storm relative helicity can be used to predict the falling area of the easterly wave heavy rainfall in advance.
The heavy rainfall process occurred on 30 July 1988 around the southeastern coast of Zhejiang Province is investigated by 05° NCEP Climate Forecast System Reanalysis data. It is found that the heavy rainfall was mainly caused by the merging of two low level east wind perturbations from south and north, respectively, and its interaction with upper level jets. The south and north branches of the easterly wave originated from the abrupt westerly, southerly evolution of the subtropical anticyclone, and the development of convective perturbations triggered by the typhoon inverted trough, respectively. The east west oriented upper level jet was formed under the combined forcing of the upper level cold vortex and the Huabei anticyclone system. The upper level jet possessed an obvious downward transmission feature in momentum, which would enhance the easterly wind component at middle troposphere and form a deep easterly wave system. The convective available potential energy (CAPE) in the heavy rainfall event of 30 July 1988 was mainly caused by the advection of air mass on the sea. The convergence in low pressure converted trough could accumulate water content in air and form a deep level with high equivalent potential temperature. This high equivalent potential temperature level may moved westward along with the easterly wave system and concentrate CAPE to convection development. There existed cold advection at the upper troposphere which could make the value of CAPE maintain steady during the westerly moving of easterly wave. The potential possibility of heavy rainfall caused by moving easterly wave could not be predicted by the single point sounding on the ground. The storm relative helicity matched with the easterly wave system very well and from it the emerging process of the south and north branches of east wind perturbations could be reflected clearly. The moving speed of the storm relative helicity was a little faster than that of the easterly wave system and vertical vorticity, and therefore the storm relative helicity can be used to predict the falling area of the easterly wave heavy rainfall in advance.
2013, 41(4):736-741.
Abstract:
The ensemble based variational method (EnVar) is used to study a retrievable problem about turbulence viscosity coefficient in the atmospheric boundary layer EK model.By using the EnVar, the gradient expression of the cost function in retrieving turbulence viscosity coefficient is deduced, and the retrievable calculation solutions are given. A series of ideal numerical experiments are conducted on the retrieving of turbulence viscosity coefficient. The results of numerical experimentations show that it is successful to use the EnVar to retrieve the turbulence viscosity coefficient in the EK model. In addition, through adjusting ensemble number, initial disturbance mean variance, and initial value appropriately, the inversion precision can be further enhanced. It is feasible to use the EnVar to retrieve the parameter of atmospheric boundary layer.
The ensemble based variational method (EnVar) is used to study a retrievable problem about turbulence viscosity coefficient in the atmospheric boundary layer EK model.By using the EnVar, the gradient expression of the cost function in retrieving turbulence viscosity coefficient is deduced, and the retrievable calculation solutions are given. A series of ideal numerical experiments are conducted on the retrieving of turbulence viscosity coefficient. The results of numerical experimentations show that it is successful to use the EnVar to retrieve the turbulence viscosity coefficient in the EK model. In addition, through adjusting ensemble number, initial disturbance mean variance, and initial value appropriately, the inversion precision can be further enhanced. It is feasible to use the EnVar to retrieve the parameter of atmospheric boundary layer.
2013, 41(4):742-747.
Abstract:
The aircraft DMT observation data from a stratus cloud precipitation on 14 May 2010 are analyzed. The results show that the main microphysical mechanism in the precipitation was a “seeder feeder” process. The concentration of precipitating particles in the ice layer was higher than those in the other layers. Ice and water particles coexisted in the supercooled layer, which had abundant liquid water content (LWC), was favorable for the ice water transformation and ice riming growth and was a crucial layer for precipitation. The mechanism of this precipitating cloud was a typical “seeder feeder” process, but the precipitating cloud had the characteristics of high cloud base, thin warm level, thick evaporation layer and lacking of warm rain growing process, so that there was no strong rainfall.
The aircraft DMT observation data from a stratus cloud precipitation on 14 May 2010 are analyzed. The results show that the main microphysical mechanism in the precipitation was a “seeder feeder” process. The concentration of precipitating particles in the ice layer was higher than those in the other layers. Ice and water particles coexisted in the supercooled layer, which had abundant liquid water content (LWC), was favorable for the ice water transformation and ice riming growth and was a crucial layer for precipitation. The mechanism of this precipitating cloud was a typical “seeder feeder” process, but the precipitating cloud had the characteristics of high cloud base, thin warm level, thick evaporation layer and lacking of warm rain growing process, so that there was no strong rainfall.
2013, 41(4):748-752.
Abstract:
Based on the sand dust weather data and air pollution index from 2005 to 2009, the air quality characteristics of Fujian coastal cities influenced by dust aerosols are analyzed. The air mass backward trajectory simulation method is employed to analyze the dust aerosol sources and transport paths. The results show that the number of days in which air PM10 concentration was influenced by dust aerosols was determined the number of dust events mainly, and the numbers of days influenced by dust in 2006 and 2007 are relatively larger. The monthly change of the number of days influenced by dust aerosol presented a typical single peak, larger between March and June. 〖JP2〗The air pollution index was higher during the dust aerosol period, and the mean API often exceeded the mild pollution degree. Visibility was positively correlated to PM10 during the dust aerosol period. There are three transportation paths: north, west, and northwest. The dust air masses moved toward Fujian coastal cities by the northwest path and north path mainly, with 11 times through the northwest path (50%) and 10 times through the north path (45%) at 300 m and 12 times through the northwest path (57%) and 5 times through the north path (24%) at 800 m altitude.
Based on the sand dust weather data and air pollution index from 2005 to 2009, the air quality characteristics of Fujian coastal cities influenced by dust aerosols are analyzed. The air mass backward trajectory simulation method is employed to analyze the dust aerosol sources and transport paths. The results show that the number of days in which air PM10 concentration was influenced by dust aerosols was determined the number of dust events mainly, and the numbers of days influenced by dust in 2006 and 2007 are relatively larger. The monthly change of the number of days influenced by dust aerosol presented a typical single peak, larger between March and June. 〖JP2〗The air pollution index was higher during the dust aerosol period, and the mean API often exceeded the mild pollution degree. Visibility was positively correlated to PM10 during the dust aerosol period. There are three transportation paths: north, west, and northwest. The dust air masses moved toward Fujian coastal cities by the northwest path and north path mainly, with 11 times through the northwest path (50%) and 10 times through the north path (45%) at 300 m and 12 times through the northwest path (57%) and 5 times through the north path (24%) at 800 m altitude.
2013, 41(4):753-757.
Abstract:
The subways are engineering construction projects with highly centralized mechatronic, electrical, and electronic systems. The lightning brings about serious threat to subway control systems, and the safety of passengers and staff personal. Through calculating of the number of the predicted lightning strikes at the elevated stations of newly built five subways in Beijing, the significance of the subway system in megapolises and the severity of lightning accident consequence and other factors are analyzed. The results indicate that the elevated subway stations (and the elevated section) are determined as the second type of buildings for lightning protection. The analysis of the lightning strike possibility of running trains indicates that the special surge protector devices should be installed in the contact rail and walking tracks according to a certain interval, so to strengthen and improve the lightning protection of traction power supply. The advantages and disadvantages of using separating series gaps in the elevated bridge grounding are analyzed. The idea of reducing or stopping the use of the separating series gaps, rather strengthening the corrosion protection design of stray current is discussed.
The subways are engineering construction projects with highly centralized mechatronic, electrical, and electronic systems. The lightning brings about serious threat to subway control systems, and the safety of passengers and staff personal. Through calculating of the number of the predicted lightning strikes at the elevated stations of newly built five subways in Beijing, the significance of the subway system in megapolises and the severity of lightning accident consequence and other factors are analyzed. The results indicate that the elevated subway stations (and the elevated section) are determined as the second type of buildings for lightning protection. The analysis of the lightning strike possibility of running trains indicates that the special surge protector devices should be installed in the contact rail and walking tracks according to a certain interval, so to strengthen and improve the lightning protection of traction power supply. The advantages and disadvantages of using separating series gaps in the elevated bridge grounding are analyzed. The idea of reducing or stopping the use of the separating series gaps, rather strengthening the corrosion protection design of stray current is discussed.
2013, 41(4):758-763.
Abstract:
Through investigating the lightning disasters of ancient buildings, the distribution of ancient buildings being stricken by lightning are analyzed. It is found that animal finials and prominent parts of the like, old trees, towers and kiosks, service facilities and other parts of ancient buildings are vulnerable to lightning strikes. It is found that once an ancient building is stricken by lightning, it is probable to be stricken again by lightning. The reasons for that ancient buildings are stricken and caught fire by lightning are analyzed, and the proportions of casualties caused by ancient building lightning disasters are calculated. It is concluded that the reasons for ancient buildings stricken by lightning includes the appropriate location and structure of ancient buildings, tree triggering, internal environment changes, and water infiltration because of disrepair and other factors vulnerable to lightning.
Through investigating the lightning disasters of ancient buildings, the distribution of ancient buildings being stricken by lightning are analyzed. It is found that animal finials and prominent parts of the like, old trees, towers and kiosks, service facilities and other parts of ancient buildings are vulnerable to lightning strikes. It is found that once an ancient building is stricken by lightning, it is probable to be stricken again by lightning. The reasons for that ancient buildings are stricken and caught fire by lightning are analyzed, and the proportions of casualties caused by ancient building lightning disasters are calculated. It is concluded that the reasons for ancient buildings stricken by lightning includes the appropriate location and structure of ancient buildings, tree triggering, internal environment changes, and water infiltration because of disrepair and other factors vulnerable to lightning.
2013, 41(4):764-770.
Abstract:
Using the routine meteorological data and AMDAR aircraft meteorological data, the objective diagnostic analysis of two severe aircraft icing events happened on 5 and 23 January 2012 in Guiyang Airport is made. The results show that these two severe aircraft icing events were caused by a stationary front; an inversion layer maintained a long time; the inversion layer top and inversion thickness were essentially the same; temperature inversion strength was enhanced; saturated cold clouds maintained and cold cloud water content continued to increase; the low level inversion layer and saturated wet layer supplied favorable temperature and moisture conditions for severe icing. AMDAR data is a strong complement to radiosonde data, which can reveal the subtle changes of atmospheric stratification over time and provide references for icing warning and forecast service.
Using the routine meteorological data and AMDAR aircraft meteorological data, the objective diagnostic analysis of two severe aircraft icing events happened on 5 and 23 January 2012 in Guiyang Airport is made. The results show that these two severe aircraft icing events were caused by a stationary front; an inversion layer maintained a long time; the inversion layer top and inversion thickness were essentially the same; temperature inversion strength was enhanced; saturated cold clouds maintained and cold cloud water content continued to increase; the low level inversion layer and saturated wet layer supplied favorable temperature and moisture conditions for severe icing. AMDAR data is a strong complement to radiosonde data, which can reveal the subtle changes of atmospheric stratification over time and provide references for icing warning and forecast service.
2013, 41(4):771-776.
Abstract:
The mountain equivalent rainfall concepts and calculation methods are proposed, borrowing from the national rainstorm warning standards for the debris flow early warning, so that they can be used as a uniform standard for both rainstorms and debris flow warning. The functions of the mountain equivalent rainfall ultimately are based on three facts: (1) the national standard is two times as much as the western mountain standard for the same storm warning; (2) most of the debris flow disasters occur around the altitude of 1300 m; and (3) the relationships between altitude and disaster can be described with Gaussian distribution, which is used widely as the formula by meteorological and land planning departments to determine the potential effect of pre precipitation accumulated rainfall on debris flow. The mountain equivalent rainfall formula can achieve the desired effect in the sampling simulation and evaluation tests and various environments, such as plains, mountains, and the plateau at different altitudes. The mountain equivalent rainfall formula has been used in the automatic releasing on a web site for debris flow early warning and analysis. Its application results need to be further verified in practice.
The mountain equivalent rainfall concepts and calculation methods are proposed, borrowing from the national rainstorm warning standards for the debris flow early warning, so that they can be used as a uniform standard for both rainstorms and debris flow warning. The functions of the mountain equivalent rainfall ultimately are based on three facts: (1) the national standard is two times as much as the western mountain standard for the same storm warning; (2) most of the debris flow disasters occur around the altitude of 1300 m; and (3) the relationships between altitude and disaster can be described with Gaussian distribution, which is used widely as the formula by meteorological and land planning departments to determine the potential effect of pre precipitation accumulated rainfall on debris flow. The mountain equivalent rainfall formula can achieve the desired effect in the sampling simulation and evaluation tests and various environments, such as plains, mountains, and the plateau at different altitudes. The mountain equivalent rainfall formula has been used in the automatic releasing on a web site for debris flow early warning and analysis. Its application results need to be further verified in practice.
2013, 41(4):777-783.
Abstract:
To meet refined wind speed forecasting needs for wind farms, using output numerical prediction products of the MM5 model, measured meteorological data of two offshore wind towers around the coastal areas of Fujian, and the stepwise regressive statistical method, hourly wind speed prediction equations for the given layers of these two towers are fitted with both MM5 numerical prediction factors and measured wind tower factors being introduced into the regression equation. The implementation process of this method is described in detail. Based on forecasting performance metrics in one year and the effect of independent sample test for 15 days， the result shows certain value of this method to hourly wind speed forecasting.
To meet refined wind speed forecasting needs for wind farms, using output numerical prediction products of the MM5 model, measured meteorological data of two offshore wind towers around the coastal areas of Fujian, and the stepwise regressive statistical method, hourly wind speed prediction equations for the given layers of these two towers are fitted with both MM5 numerical prediction factors and measured wind tower factors being introduced into the regression equation. The implementation process of this method is described in detail. Based on forecasting performance metrics in one year and the effect of independent sample test for 15 days， the result shows certain value of this method to hourly wind speed forecasting.
2013, 41(4):784-789.
Abstract:
A mesoscale numerical weather prediction model and the BP neural network forecasting model are used to predict wind farm wind power. By using the WRF numerical model, the meteorological elements from June 2008 to June 2009 of wind are calculated, and results show that the correlation coefficient between forecast and measured wind speed is 072 The forecasts of wind direction, temperature, humidity, and air pressure are also relatively accurate. The BP neural network forecast model of wind power for 40 wind turbines are established, and the influences of the data standardization method and the number of hidden neurons on prediction are analyzed. The results of trial prediction show that the relative RMS error of a single wind generator is 248% to 326%; the correlation coefficient is 045 to 068; and those for the whole wind farm are 215% and 074.
A mesoscale numerical weather prediction model and the BP neural network forecasting model are used to predict wind farm wind power. By using the WRF numerical model, the meteorological elements from June 2008 to June 2009 of wind are calculated, and results show that the correlation coefficient between forecast and measured wind speed is 072 The forecasts of wind direction, temperature, humidity, and air pressure are also relatively accurate. The BP neural network forecast model of wind power for 40 wind turbines are established, and the influences of the data standardization method and the number of hidden neurons on prediction are analyzed. The results of trial prediction show that the relative RMS error of a single wind generator is 248% to 326%; the correlation coefficient is 045 to 068; and those for the whole wind farm are 215% and 074.
External LinksChina Meteorological AdministrationCMA Meteorological Observation CentreChinese Academy of Meteorological SciencesBeijing Meteorological ServiceNational Satellite Meteorological Center
You are thevisitors
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.