Volume 35,Issue 5,2007 Table of Contents
2007, 35(5):613-620.
Abstract:
A new numerical model with a new algorithm of the Coons bicubic curved surface fitting by means of “bicubic curved surface fitting-time step integration-bicubic curved-surface fitting...” is presented. Obviously, this model can give a nonlinear description to atmospheric motion and can get the solution (approximate numerical solution) of a nonlinear partial differential equation system by the numerical analysis method. Actually, with the cubic spline function, BiNM is a Coons bicubic curvedsurface fitting model for many physical fields of the atmospheric motion in the x, y, or z directions (but the timedimension is not considered here). It can make the fitting of the synoptic system by a continuous regular polyhedrons composed with N pieces of Hermite bicubic patches in mathematical RN space. By this kind of fitting, the atmospheric physical field P, as well as its differential PX and PXX, and P's integral in the X (X = x, y, z) space can be all obtained at any time. It is indicated that, by the differential quotient instead of linear difference, BiNM can describe multiscale and nonlinear atmospheric motions and forecast (simulate) them by time integration for their governing equations. A Bicubic Numerical Model (BiNM) with the Z coordinate system and high resolution (22 m grid spacing in horizontal and 52 layers in vertical) is used. An ideal predefined disturbance of mospheric acoustic waves (Lamb waves) is simulated by using the primary atmospheric equations of motion and the Eulerian time integration scheme; meanwhile, the same gravity wave as an ideal tornado disturbance is also simulated by assuming that the free atmosphere be incompressible, such that the acoustic wave is eliminated in the simulation, showing that tornados are not acoustic waves but gravity waves in the atmosphere. It is also found that: (1) the simulated Lamb wave would propagate in horizontal direction at a speed similar to the speed of acoustic waves in the atmosphere and last for only a few seconds at its original place, in which energy dispersion is much more quickly than tornado disturbance; (2) like gravity wave in the atmosphere, the simulated tornado disturbance can last for more than one minute at its original place, and its inner (outer) part is all the while a convergence (divergence) circle from its bottom up, having a cold core and showing stationary wave features. The tornado disturbance can develop from the input of water vapor into the disturbance and the releasing of condensation latent heat. Under the incompressible flow assumption, a wetadiabatic energy balance equation is derived, which theoretically proved that condensation latent heat can help the development of a tornado.
A new numerical model with a new algorithm of the Coons bicubic curved surface fitting by means of “bicubic curved surface fitting-time step integration-bicubic curved-surface fitting...” is presented. Obviously, this model can give a nonlinear description to atmospheric motion and can get the solution (approximate numerical solution) of a nonlinear partial differential equation system by the numerical analysis method. Actually, with the cubic spline function, BiNM is a Coons bicubic curvedsurface fitting model for many physical fields of the atmospheric motion in the x, y, or z directions (but the timedimension is not considered here). It can make the fitting of the synoptic system by a continuous regular polyhedrons composed with N pieces of Hermite bicubic patches in mathematical RN space. By this kind of fitting, the atmospheric physical field P, as well as its differential PX and PXX, and P's integral in the X (X = x, y, z) space can be all obtained at any time. It is indicated that, by the differential quotient instead of linear difference, BiNM can describe multiscale and nonlinear atmospheric motions and forecast (simulate) them by time integration for their governing equations. A Bicubic Numerical Model (BiNM) with the Z coordinate system and high resolution (22 m grid spacing in horizontal and 52 layers in vertical) is used. An ideal predefined disturbance of mospheric acoustic waves (Lamb waves) is simulated by using the primary atmospheric equations of motion and the Eulerian time integration scheme; meanwhile, the same gravity wave as an ideal tornado disturbance is also simulated by assuming that the free atmosphere be incompressible, such that the acoustic wave is eliminated in the simulation, showing that tornados are not acoustic waves but gravity waves in the atmosphere. It is also found that: (1) the simulated Lamb wave would propagate in horizontal direction at a speed similar to the speed of acoustic waves in the atmosphere and last for only a few seconds at its original place, in which energy dispersion is much more quickly than tornado disturbance; (2) like gravity wave in the atmosphere, the simulated tornado disturbance can last for more than one minute at its original place, and its inner (outer) part is all the while a convergence (divergence) circle from its bottom up, having a cold core and showing stationary wave features. The tornado disturbance can develop from the input of water vapor into the disturbance and the releasing of condensation latent heat. Under the incompressible flow assumption, a wetadiabatic energy balance equation is derived, which theoretically proved that condensation latent heat can help the development of a tornado.
2007, 35(5):621-625.
Abstract:
The horizontal distributing characteristics of potential energy in three types of heavy rainfall are studied on the basis of energy synoptic principles. The heavy rain process on 11 August 1999 in Shandong Province is analyzed in aspects of horizontal and vertical potential energy and energy frontogenesis characteristics. The result shows that potential energy plays a good indicative role in heavy rain forecasting. The appearance of only high energy value does not mean heavy rainfall; but when the more powerful energy frontal zone and negative energy frontogenetical function zone move to the area and the convergence condition in the lower layer is favorable at the same time, severe precipitation is likely to occur. The heavy rain of August 1999 occurred at the front of the energy frontal zone, and the vertical distribution of potential energy can indicate the movement of cold air.
The horizontal distributing characteristics of potential energy in three types of heavy rainfall are studied on the basis of energy synoptic principles. The heavy rain process on 11 August 1999 in Shandong Province is analyzed in aspects of horizontal and vertical potential energy and energy frontogenesis characteristics. The result shows that potential energy plays a good indicative role in heavy rain forecasting. The appearance of only high energy value does not mean heavy rainfall; but when the more powerful energy frontal zone and negative energy frontogenetical function zone move to the area and the convergence condition in the lower layer is favorable at the same time, severe precipitation is likely to occur. The heavy rain of August 1999 occurred at the front of the energy frontal zone, and the vertical distribution of potential energy can indicate the movement of cold air.
2007, 35(5):626-630.
Abstract:
The correlation coefficients between tropical cyclone frequency and geopotential height field of 500 hPa and seasurface temperature (SST) of the Pacific Ocean are calculated. By analyzing the statistical characteristics of those in highly significant regions, an investigation is conducted on their synoptic and climatological significance and physical characteristics. Several high correlated factors (selected and combined) are used to construct the dynamic prediction binomial equations to predict the yearly and monthly frequencies of tropical cyclones over the South China Sea and Guangdong Province. The results show that the prediction model has high fitting ability and performs well.
The correlation coefficients between tropical cyclone frequency and geopotential height field of 500 hPa and seasurface temperature (SST) of the Pacific Ocean are calculated. By analyzing the statistical characteristics of those in highly significant regions, an investigation is conducted on their synoptic and climatological significance and physical characteristics. Several high correlated factors (selected and combined) are used to construct the dynamic prediction binomial equations to predict the yearly and monthly frequencies of tropical cyclones over the South China Sea and Guangdong Province. The results show that the prediction model has high fitting ability and performs well.
2007, 35(5):631-636.
Abstract:
The destructive gusts and wind shear caused by downbursts are great threats to human's daily life and the taking off or landing of planes. Doppler radar plays important roles on monitoring and predicting downbursts for its high temporal and spatial resolution. The current status of researches on downburst monitoring with Doppler radar both at home and abroad is summarized and the prospects are discussed. Introduction is also made to the basic concepts and echo features of downbursts, as well as the main algorithms used presently, including the shearsegment method, imageprocessing method, and linear discriminant analysis.
The destructive gusts and wind shear caused by downbursts are great threats to human's daily life and the taking off or landing of planes. Doppler radar plays important roles on monitoring and predicting downbursts for its high temporal and spatial resolution. The current status of researches on downburst monitoring with Doppler radar both at home and abroad is summarized and the prospects are discussed. Introduction is also made to the basic concepts and echo features of downbursts, as well as the main algorithms used presently, including the shearsegment method, imageprocessing method, and linear discriminant analysis.
2007, 35(5):637-641.
Abstract:
The potential prediction of 0 to 12 hours is conducted for strong convective weather based on MM5 and the diagnosis of instability and energy indexes. The stormtracing information of Doppler radar is used in the 0 to 1 hour nowcasting of strong convective weather. The stormtracing information contains the motion direction and velocity of radar echoes. By means of the trial use in severe convective processes, the comparison is made between prediction and real condition. The experiments are conducted on some strong convective weather events in recent years with the shortterm potential prediction method. The results show that both methods are valuable in forecasting strong storms.
The potential prediction of 0 to 12 hours is conducted for strong convective weather based on MM5 and the diagnosis of instability and energy indexes. The stormtracing information of Doppler radar is used in the 0 to 1 hour nowcasting of strong convective weather. The stormtracing information contains the motion direction and velocity of radar echoes. By means of the trial use in severe convective processes, the comparison is made between prediction and real condition. The experiments are conducted on some strong convective weather events in recent years with the shortterm potential prediction method. The results show that both methods are valuable in forecasting strong storms.
2007, 35(5):642-645.
Abstract:
The precipitation classification forecast model of flooding for the mountain areas of central Shandong Province, was built based on T213 data and precipitation data from Jinan, Zibo, Taian and Laiwu by applying the Support Vector Machine (SVM) method. The results indicate that the model based on the polynomial kernel and the model based on radial basic function kernel can extract well precipitation information, and both have good forecast skill and prediction capabilities, but the later is better especially when the data is insufficient. The lowerlayer moisture has a great influence on the model based on the polynomial kernel. The data used in modeling should keep as consistent as possible with the data used in operation in data format.
The precipitation classification forecast model of flooding for the mountain areas of central Shandong Province, was built based on T213 data and precipitation data from Jinan, Zibo, Taian and Laiwu by applying the Support Vector Machine (SVM) method. The results indicate that the model based on the polynomial kernel and the model based on radial basic function kernel can extract well precipitation information, and both have good forecast skill and prediction capabilities, but the later is better especially when the data is insufficient. The lowerlayer moisture has a great influence on the model based on the polynomial kernel. The data used in modeling should keep as consistent as possible with the data used in operation in data format.
2007, 35(5):646-650.
Abstract:
Four indexes are defined to describe the position and intensity characteristics of Siberian High (SH) based on the NCEP/NCAR monthly mean data from 1948 to 2005. By analyzing the indexes, the features of the SH's normal and anomaly variations are examined. The findings conclude that SH indexes have obvious interannual and interdecadal variations; at the interdecadal scale, SH has the trend of decreasing/diminishing with time at first, then increasing/expading; as for position variation, SH moved at first toward west, then east, and west again after 1999; the area, intensity, and central latitudes anomalies of SH are closely related to winter temperature; and the SH longitude anomaly has little effect on winter temperature anomalies. The SH abnormal area is correlated with major winter temperature anomalies at the decadal time scale. When the SH area and intensity increase abnormally, there occurs abnormal winter temperature in China, increasing in Southweast China and decreasing in the other parts of China, especially in the southern Northeast, nothern Xingjiang, and a part of Sounth China.
Four indexes are defined to describe the position and intensity characteristics of Siberian High (SH) based on the NCEP/NCAR monthly mean data from 1948 to 2005. By analyzing the indexes, the features of the SH's normal and anomaly variations are examined. The findings conclude that SH indexes have obvious interannual and interdecadal variations; at the interdecadal scale, SH has the trend of decreasing/diminishing with time at first, then increasing/expading; as for position variation, SH moved at first toward west, then east, and west again after 1999; the area, intensity, and central latitudes anomalies of SH are closely related to winter temperature; and the SH longitude anomaly has little effect on winter temperature anomalies. The SH abnormal area is correlated with major winter temperature anomalies at the decadal time scale. When the SH area and intensity increase abnormally, there occurs abnormal winter temperature in China, increasing in Southweast China and decreasing in the other parts of China, especially in the southern Northeast, nothern Xingjiang, and a part of Sounth China.
2007, 35(5):651-654.
Abstract:
An analysis is made of the relation between summer precipitation and antecedent circulation by using NCAR/NCEP 500hPa reanalysis data and summer precipitation data from central North China from 1957 to 2002. The results show that there is obvious correlation between summer precipitation, the intensity of winter East Asian Trough and the spring height field over the Mongolia Plateau from Balkhash to Baikal. Winter East Asian Trough was stronger and the height over the Mongolia Plateau in spring was lower than normal before the middle 1980s, but vice versa after 1985. The trend is consistent with the variation of summer precipitation. It is demonstrated that the reasons for summer precipitation decrease include the weakened winter East Asian Trough and higher spring Mongolia Plateau height field. When the winter East Asian Trough is strong, the summer West Pacific Subtropical High is strong over the Japan sea region correspondingly, which is favorable for the increase of summer precipitation over the central North China. When the heights of the spring Mongolia Plateau height field are higher, it is favorable for the occurrence of the circulation pattern “high in the west and low in the east," in which lessthannormal summer precipitation in central North China is likely to happen.
An analysis is made of the relation between summer precipitation and antecedent circulation by using NCAR/NCEP 500hPa reanalysis data and summer precipitation data from central North China from 1957 to 2002. The results show that there is obvious correlation between summer precipitation, the intensity of winter East Asian Trough and the spring height field over the Mongolia Plateau from Balkhash to Baikal. Winter East Asian Trough was stronger and the height over the Mongolia Plateau in spring was lower than normal before the middle 1980s, but vice versa after 1985. The trend is consistent with the variation of summer precipitation. It is demonstrated that the reasons for summer precipitation decrease include the weakened winter East Asian Trough and higher spring Mongolia Plateau height field. When the winter East Asian Trough is strong, the summer West Pacific Subtropical High is strong over the Japan sea region correspondingly, which is favorable for the increase of summer precipitation over the central North China. When the heights of the spring Mongolia Plateau height field are higher, it is favorable for the occurrence of the circulation pattern “high in the west and low in the east," in which lessthannormal summer precipitation in central North China is likely to happen.
Jia Jinming
,
Wu Jianhe
,
Xu Qiaozhen
,
Zhang Mingjie
,
Mao Guiping
,
Li Hanjin
,
Liu Ping
,
Wang Chunling
2007, 35(5):655-660.
Abstract:
The features of sunshine duration variation in Henan Province and Puyang are analyzed with the linear analysis method by means of the data of 1994 to 2005 from 32 stations. The results indicate that sunshine duration in Henan Province decreased with a tendency of 74.2 hours per ten years, and the decreasing amplitude over the eastern plain areas was obviously greater than those in the western mountainous areas. At Puyang, the sunshine duration decreased by 135 hours per 10 years, with a bigger decreasing amplitude in winter and summer than in spring and autumn. The decrease occured mostly after sunrise and before sunset when the solar altitude angle was relatively low. The meteorological causes include the more and more serious air pollution on an annual basis and the wind velocity decrease, which are favorable for the accumulation of the atmospheric aerosols in the atmosphere at low altitudes and the increase of air humidity and light fog days, resulting in the decrease of atmospheric transparency. The main nonmeteorological factor is that the altitude angle of the obstructions around the observation station is getting higher on an annual basis, which results in the partly sheltering of sunshine. The influence of meteorological factors surpasses that of nonmeteorological factors.
The features of sunshine duration variation in Henan Province and Puyang are analyzed with the linear analysis method by means of the data of 1994 to 2005 from 32 stations. The results indicate that sunshine duration in Henan Province decreased with a tendency of 74.2 hours per ten years, and the decreasing amplitude over the eastern plain areas was obviously greater than those in the western mountainous areas. At Puyang, the sunshine duration decreased by 135 hours per 10 years, with a bigger decreasing amplitude in winter and summer than in spring and autumn. The decrease occured mostly after sunrise and before sunset when the solar altitude angle was relatively low. The meteorological causes include the more and more serious air pollution on an annual basis and the wind velocity decrease, which are favorable for the accumulation of the atmospheric aerosols in the atmosphere at low altitudes and the increase of air humidity and light fog days, resulting in the decrease of atmospheric transparency. The main nonmeteorological factor is that the altitude angle of the obstructions around the observation station is getting higher on an annual basis, which results in the partly sheltering of sunshine. The influence of meteorological factors surpasses that of nonmeteorological factors.
2007, 35(5):661-664.
Abstract:
The temperature sequence data from 1953 to 2005 of Benxi are used to analyze the basic climatic characteristics, interannual variation, period variation, coldwarm variation, variation trend, etc. The results indicate that the annual mean temperature distribution was not consistent with seasonal distributions. The annual mean air temperature was the lowest in the 1950s, but the low est growingseason temperature was in the 1970s. The lowest temperature in spring was consistent with the annual mean air mperature. The lowest temperatures insummer and in autumn were found in the 1970s, and that in winter was in the 1960s. The total temperature tended to go up gradually.
The temperature sequence data from 1953 to 2005 of Benxi are used to analyze the basic climatic characteristics, interannual variation, period variation, coldwarm variation, variation trend, etc. The results indicate that the annual mean temperature distribution was not consistent with seasonal distributions. The annual mean air temperature was the lowest in the 1950s, but the low est growingseason temperature was in the 1970s. The lowest temperature in spring was consistent with the annual mean air mperature. The lowest temperatures insummer and in autumn were found in the 1970s, and that in winter was in the 1960s. The total temperature tended to go up gradually.
2007, 35(5):665-669.
Abstract:
The relations between CloudtoGround (CG) lighting activity and radarecho products, including CR (Composite Reflectivity), VIL (Vertical Integrated Liquid water), ET (Echo Top), are analyzed quantitatively and qualitatively through tracing the generation, developemnt and mitigation of a MCS (Mesoscale Convective System) thunderstorm process, after the “coarsening” grid processing of CG and Doppler data. The results show: 96.7% of CG appeared within the range of 40 to 55 dBz, and the center of maximum CG density always coincided with the center of intense echoes, but CGs seldom appeared above 65 dBz. often concentrated around the area with VIL greater than 40 kg·m-2, and the center of maximum CGdensity frequently located around the margin of the center of VIL. The number of CGs was correlated with the area of ET greater or equal to 11 km, which indicates that the area with cloud top up to a relatively high level in MCS influences greatly the intensity of CG lightning activity.
The relations between CloudtoGround (CG) lighting activity and radarecho products, including CR (Composite Reflectivity), VIL (Vertical Integrated Liquid water), ET (Echo Top), are analyzed quantitatively and qualitatively through tracing the generation, developemnt and mitigation of a MCS (Mesoscale Convective System) thunderstorm process, after the “coarsening” grid processing of CG and Doppler data. The results show: 96.7% of CG appeared within the range of 40 to 55 dBz, and the center of maximum CG density always coincided with the center of intense echoes, but CGs seldom appeared above 65 dBz. often concentrated around the area with VIL greater than 40 kg·m-2, and the center of maximum CGdensity frequently located around the margin of the center of VIL. The number of CGs was correlated with the area of ET greater or equal to 11 km, which indicates that the area with cloud top up to a relatively high level in MCS influences greatly the intensity of CG lightning activity.
2007, 35(5):670-675.
Abstract:
A heavy rain occurred in Longyan on 18 June 2006 is analyzed by using the data of routine observation, automatic weather stations, satellite pictures, and CINRAD/SA observations. The results show that the favorable environmental condition, ample water vapor condition, strong ascending movement and the invasion of weak cold air caused the heavy rainfall. The heavy rainfall was resulted from the local mesoand smallscale systems emerging from the mesoscale landform. The CINRAD/SA data indicate that the convective cells have the typical features of severe liquid precipitation. The retrieved wind field from radar data shows that the smallscale systems such as wind speed convergence and shear lines are the causes of shortrange severe precipitation.
A heavy rain occurred in Longyan on 18 June 2006 is analyzed by using the data of routine observation, automatic weather stations, satellite pictures, and CINRAD/SA observations. The results show that the favorable environmental condition, ample water vapor condition, strong ascending movement and the invasion of weak cold air caused the heavy rainfall. The heavy rainfall was resulted from the local mesoand smallscale systems emerging from the mesoscale landform. The CINRAD/SA data indicate that the convective cells have the typical features of severe liquid precipitation. The retrieved wind field from radar data shows that the smallscale systems such as wind speed convergence and shear lines are the causes of shortrange severe precipitation.
2007, 35(5):676-680.
Abstract:
For the squall line process occurred on 28 April 2006 in Jiangsu Province, the main characteristics, including its boundary layer, vertical structure, propagation evolution, and development, are analyzed. The physical causes of the surface strong wind caused by the squall line are also discussed. The results show that the squall line was activated and developed along a surface convergence line, when the squall line propagated downstream; it generated perturbation in horizontal wind field in the boundary layer, resulting in obvious disturbance features accompanying the squall line propagation. In addition, the drag effect of rain particles, in cooperation with the down stream at the back of squall line, played a crucial role in generating the surface strong wind.
For the squall line process occurred on 28 April 2006 in Jiangsu Province, the main characteristics, including its boundary layer, vertical structure, propagation evolution, and development, are analyzed. The physical causes of the surface strong wind caused by the squall line are also discussed. The results show that the squall line was activated and developed along a surface convergence line, when the squall line propagated downstream; it generated perturbation in horizontal wind field in the boundary layer, resulting in obvious disturbance features accompanying the squall line propagation. In addition, the drag effect of rain particles, in cooperation with the down stream at the back of squall line, played a crucial role in generating the surface strong wind.
2007, 35(5):681-686.
Abstract:
Sanddust storms in Gansu Province occurred most frequently in summer. The summer sanddust storms concentrated around Minqin, Dingxin and Jinta. The weather patterns for severe sanddust storms in summer in Gansu Province are analyzed. The results show that upper troughs and shear lines and hot lows are main synoptic systems that result in summer sanddust storms. Spring sanddust stor ms are mostly induced by largescale synoptic systems. Before the occurrence of summer sanddust storms, the upperlevel jet currents are not apparent. The sudden wind speed increase of the jet stream happens almost at the same time with a sanddust storm, and that is one of difficulties in summer sanddust storm prediction. The helicity field 8 to 12 hours before sanddust storm occurring is a good indicator in forecasting sanddust storms. The larger the helicity is, the severer the sanddust storm is. But when a sanddust storm and severe precipitation occur concurrently, the value of helicity in the sanddust storm region is obviously less than that in the severe precipitation region.
Sanddust storms in Gansu Province occurred most frequently in summer. The summer sanddust storms concentrated around Minqin, Dingxin and Jinta. The weather patterns for severe sanddust storms in summer in Gansu Province are analyzed. The results show that upper troughs and shear lines and hot lows are main synoptic systems that result in summer sanddust storms. Spring sanddust stor ms are mostly induced by largescale synoptic systems. Before the occurrence of summer sanddust storms, the upperlevel jet currents are not apparent. The sudden wind speed increase of the jet stream happens almost at the same time with a sanddust storm, and that is one of difficulties in summer sanddust storm prediction. The helicity field 8 to 12 hours before sanddust storm occurring is a good indicator in forecasting sanddust storms. The larger the helicity is, the severer the sanddust storm is. But when a sanddust storm and severe precipitation occur concurrently, the value of helicity in the sanddust storm region is obviously less than that in the severe precipitation region.
2007, 35(5):687-691.
Abstract:
The ideas behind the design, structure, procedure, and functions of the cloud seeding operational system for impounding water in a reservoir are described according to the characteristics of cloud seeding for increasing water in reservoirs. The approaches to realize these functions are introduced technically. The application experiment conduced in Dabieshan Moutain in the western Anhui Province is discussed. The system is simple and easy to use in the aspects of demand analysis, weather warning, operation control, effectiveness evaluation, data management, report making, and user platform, which can provide useful references for the establishment of similar operational precipitation enhancement systems.
The ideas behind the design, structure, procedure, and functions of the cloud seeding operational system for impounding water in a reservoir are described according to the characteristics of cloud seeding for increasing water in reservoirs. The approaches to realize these functions are introduced technically. The application experiment conduced in Dabieshan Moutain in the western Anhui Province is discussed. The system is simple and easy to use in the aspects of demand analysis, weather warning, operation control, effectiveness evaluation, data management, report making, and user platform, which can provide useful references for the establishment of similar operational precipitation enhancement systems.
2007, 35(5):692-695.
Abstract:
A PDAbased diffusion simulating system of weather modification is introduced briefly, and the system design and technical nnovative points of the system are described. The system focuses on the conversion of the findings in theoretical researches on catalyst diffusion into computeraided applied technology and can simulate the diffusion process of cloud seeding through the fast computeraided visualization processing to provide support for the design of weather modification operation schemes, being simple and easy to use. Considering the needs of weather modification operations in the system analysis and design, the system has the rational data structure, software architecture, and visualized and friendly manmachine interaction interface.
A PDAbased diffusion simulating system of weather modification is introduced briefly, and the system design and technical nnovative points of the system are described. The system focuses on the conversion of the findings in theoretical researches on catalyst diffusion into computeraided applied technology and can simulate the diffusion process of cloud seeding through the fast computeraided visualization processing to provide support for the design of weather modification operation schemes, being simple and easy to use. Considering the needs of weather modification operations in the system analysis and design, the system has the rational data structure, software architecture, and visualized and friendly manmachine interaction interface.
2007, 35(5):696-698.
Abstract:
A remotecontrolled groundbased flare seeding system through mobilephone Short Message Service (SMS) was developed. Since the ignition signals are issued by means of SMS, the system can be operated remotely and automatically. The system consists of a smoke generator, flares, computer and the related software. A total of 36 flares can be placed in the generator at one time. Each flare contains 500 g of BR91Y pyrotechnics (7.5 g AgI). The control system can work anywhere within the coverage of the mobilephone network. The system is controlled by a computer, being easy to use. It was applied in April and May 2006 in the Yulong Mountain region to enhance snowfall. The problems emerged during the experiment are discussed, and some solutions are presented. The experiment shows that the system performs well and has great potential in application.
A remotecontrolled groundbased flare seeding system through mobilephone Short Message Service (SMS) was developed. Since the ignition signals are issued by means of SMS, the system can be operated remotely and automatically. The system consists of a smoke generator, flares, computer and the related software. A total of 36 flares can be placed in the generator at one time. Each flare contains 500 g of BR91Y pyrotechnics (7.5 g AgI). The control system can work anywhere within the coverage of the mobilephone network. The system is controlled by a computer, being easy to use. It was applied in April and May 2006 in the Yulong Mountain region to enhance snowfall. The problems emerged during the experiment are discussed, and some solutions are presented. The experiment shows that the system performs well and has great potential in application.
2007, 35(5):699-702.
Abstract:
By means of the data of daily precipitation, temperature, humidity, wind speed, and wind direction from 10 May to 10 June, 1971 to 2005 as well as thousand grain weight data of winter wheat from 1981 to 2005 in Hebei winter wheat production area, with the statistical methods, such as wavelet analysis, regression analysis, etc., the temporalspatial distribution features, the variation periods of dryhot wind and its impacts on thousand grain weight of winter wheat are analyzed. The results indicate that the annual mean number of mild dryhot wind days is consistent with that of severe dryhot wind days; the interdecadal variation of mild and severe dryhot wind has same characteristics; the total number of dryhot wind days has a negative correlation with the thousand grain weight of winter wheat.
By means of the data of daily precipitation, temperature, humidity, wind speed, and wind direction from 10 May to 10 June, 1971 to 2005 as well as thousand grain weight data of winter wheat from 1981 to 2005 in Hebei winter wheat production area, with the statistical methods, such as wavelet analysis, regression analysis, etc., the temporalspatial distribution features, the variation periods of dryhot wind and its impacts on thousand grain weight of winter wheat are analyzed. The results indicate that the annual mean number of mild dryhot wind days is consistent with that of severe dryhot wind days; the interdecadal variation of mild and severe dryhot wind has same characteristics; the total number of dryhot wind days has a negative correlation with the thousand grain weight of winter wheat.
2007, 35(5):703-707.
Abstract:
To get an insight into the planting structure of the agropastoral region, the planting area and yields of main crops such as soybeans, corn and wheat are analyzed in combination with the related meteorological data by means of Bayesian criteria. The results show that (1) according to the economical benefits, the planting proportion from large to small should be: soybean, corn, wheat. (2) If there will be droughts according to forecast, the planting proportion should be: corn, soybean, wheat; if there will be floods or low temperature (cold damage) according to forecast, the planting proportion should be: soybean, corn, wheat. Two optimal planting proportion schemes under the dry climatic condition are designed, by using which the output value can increase by 3% and 5% or more， respectively.
To get an insight into the planting structure of the agropastoral region, the planting area and yields of main crops such as soybeans, corn and wheat are analyzed in combination with the related meteorological data by means of Bayesian criteria. The results show that (1) according to the economical benefits, the planting proportion from large to small should be: soybean, corn, wheat. (2) If there will be droughts according to forecast, the planting proportion should be: corn, soybean, wheat; if there will be floods or low temperature (cold damage) according to forecast, the planting proportion should be: soybean, corn, wheat. Two optimal planting proportion schemes under the dry climatic condition are designed, by using which the output value can increase by 3% and 5% or more， respectively.
20 Usability of Precipitation Prediction in Dynamical Controlling of Flood Control Limit for Reservoirs
2007, 35(5):708-713.
Abstract:
The probability distribution of observed precipitation grades under a certain precipitation grade is analyzed and predicted on the basis of precipitation predictions and observations in Tianjin. From the viewpoint of flood control, the emphasis is put on the possibility of underestimated precipitation events. Adopting the curve fitting method and determining the empirical statistic paramet er from the hydrological frequency distribution curve, the precipitation distributions corresponding to the precipitation prediction of each grade are estimated. Results show that the reliabilities of precipitation predictions are different, and the possibility of underestimated events is bigger than that of overestimated ones for the precipitation predictions of all grades. The procedure to use precipitation predictions for controlling the water level of the reservoir during the flooding season is presented.
The probability distribution of observed precipitation grades under a certain precipitation grade is analyzed and predicted on the basis of precipitation predictions and observations in Tianjin. From the viewpoint of flood control, the emphasis is put on the possibility of underestimated precipitation events. Adopting the curve fitting method and determining the empirical statistic paramet er from the hydrological frequency distribution curve, the precipitation distributions corresponding to the precipitation prediction of each grade are estimated. Results show that the reliabilities of precipitation predictions are different, and the possibility of underestimated events is bigger than that of overestimated ones for the precipitation predictions of all grades. The procedure to use precipitation predictions for controlling the water level of the reservoir during the flooding season is presented.
21 Statistical Analysis and Numerical Prediction Experiment of Weather Conditions for Aircraft Icing
2007, 35(5):714-718.
Abstract:
Weather conditions for airplane icing and icing characteristics are analyzed on the basis of the measurements from 90 airplane flights from March 2000 to June 2005. The PSU/NCAR MM5 model is used to replicate the process of precipitation enhancement on 16 May 2005 in Shandong, and the simulation results show that the evolvement and range of the event agree well with observation. On the b asis of success simulation, a contrast experiment between the icing index from the model output and airplane measurements is conducted. The results show that reverse troughs and cold fronts on the ground are the main weather systems during the airplane precipitation enhancement season in Shandong; the greatest percentage of mild and moderate icing occurs along with surface lowpressure troughs, but the highest probability of icing is along with Southern Cyclone, up to 53.3%. The superposed field of the icingindex from MM5 model output and vertical velocity fields can be used to describe well the area, time and intensity of icing in precipitation enhancement operations.
Weather conditions for airplane icing and icing characteristics are analyzed on the basis of the measurements from 90 airplane flights from March 2000 to June 2005. The PSU/NCAR MM5 model is used to replicate the process of precipitation enhancement on 16 May 2005 in Shandong, and the simulation results show that the evolvement and range of the event agree well with observation. On the b asis of success simulation, a contrast experiment between the icing index from the model output and airplane measurements is conducted. The results show that reverse troughs and cold fronts on the ground are the main weather systems during the airplane precipitation enhancement season in Shandong; the greatest percentage of mild and moderate icing occurs along with surface lowpressure troughs, but the highest probability of icing is along with Southern Cyclone, up to 53.3%. The superposed field of the icingindex from MM5 model output and vertical velocity fields can be used to describe well the area, time and intensity of icing in precipitation enhancement operations.
2007, 35(5):719-722.
Abstract:
The evolutionary characteristics of the meteorological elements and horizontal wind shear under southeast strong wind around the runway are analyzed on the basis of the conventional meteorological data and the realtime AWOS data from airport runways during typical southeast strong wind processes at the Urumqi international airport from 2002 to 2005. The results show: (1) the meteorologi cal elements under southeast strong wind changed significantly. The temperature rose, and the pressure and the humidity descended at the beginning and during the maintain stage, while the temperature decreased, and the pressure and humidity increased in the end. The temperature, pressure, and humidity changed abruptly at the same time when the wind weakened. (2) The strong horizontal wind shear ab ove the runway appeared because of the discontinuousness in wind direction and velocity in different places along the runway at the same time, especially at the beginning and in the end. The difference in wind velocity between two ends of the runway and its variation are dominant factors affecting the strength and variation of the wind shear.
The evolutionary characteristics of the meteorological elements and horizontal wind shear under southeast strong wind around the runway are analyzed on the basis of the conventional meteorological data and the realtime AWOS data from airport runways during typical southeast strong wind processes at the Urumqi international airport from 2002 to 2005. The results show: (1) the meteorologi cal elements under southeast strong wind changed significantly. The temperature rose, and the pressure and the humidity descended at the beginning and during the maintain stage, while the temperature decreased, and the pressure and humidity increased in the end. The temperature, pressure, and humidity changed abruptly at the same time when the wind weakened. (2) The strong horizontal wind shear ab ove the runway appeared because of the discontinuousness in wind direction and velocity in different places along the runway at the same time, especially at the beginning and in the end. The difference in wind velocity between two ends of the runway and its variation are dominant factors affecting the strength and variation of the wind shear.
23 Design of Lightning Current Energy Coordination in Surge Protective Devices in Electrical Systems
2007, 35(5):723-726.
Abstract:
An analysis is made of the design of lightning current energy coordination relevant to Surge Protective Devices (SPDs). The coordination between singlelevel SPD and protected device is studied, and the formulas for computing the maximum oscillation protection distance and maximum coupling distance are used to determine the successfulness of the coordination. The coordination between multilevel SPDs is also studied, putting the emphasis on the coordination of twolevel SPDs (switch type and voltagelimited type). The differential equation of transient voltage drop is adopted, and the size of the decoupler is determined by means of different lightningcurrent wave forms. The feasible procedure of lightning current energy coordination design for SPDs is proposed.
An analysis is made of the design of lightning current energy coordination relevant to Surge Protective Devices (SPDs). The coordination between singlelevel SPD and protected device is studied, and the formulas for computing the maximum oscillation protection distance and maximum coupling distance are used to determine the successfulness of the coordination. The coordination between multilevel SPDs is also studied, putting the emphasis on the coordination of twolevel SPDs (switch type and voltagelimited type). The differential equation of transient voltage drop is adopted, and the size of the decoupler is determined by means of different lightningcurrent wave forms. The feasible procedure of lightning current energy coordination design for SPDs is proposed.
24 Performance Evaluation of Hail Detection with CIANRAD/SA Radar and Localization of Hail Parameters
Diao Xiuguang
,
Huang Xiushao
,
Ren zhongdong
,
Yang Chuanfeng
,
Liu Zhihong
,
Geng Li
,
Zhu Junjian
2007, 35(5):727-731.
Abstract:
An enhanced hail detection algorithm (HDA) for the CINRAD/SA radar replaced the original hail algorithm in 2004. The new HDA can estimate the probability of hail (POH, any size), severe hail (diameter greater that 19 mm), and expected maximumsize hail for each detected storm cell. The performance of POH detection is evaluated with Jinan's CINRAD/SA data, using 50% as the warning threshold for the POH parameter, and the verification against hail observations of any size is conducted, and the following accuracy measures are obtained: POD (Probability Of Detection) is 100%, FAR (Falas Alarm Ratio) is 72.2%，CSI (Critical Success Index) is 88%. The expected maximum hail size is 14.6 mm bigger than the actual maximum hail size averagely. Using JinanCINRAD/SA data of 2001 to 2005, the distributive characteristics of the maximum reflectivity in the cases of convective clouds are analyzed. The maximum reflectivities are 59.7, 61.8, 63.9 dBz for hailstorms and 53.8, 54.9, 55.6 dBz for nonhail storms in May, June and July, respectively. So the minimum and maximum reflectivities of a component used in the calculation of the probability of hail are modulated from 45 to 53 dBz, and FAR and CSI are improved obviously. Through adjusting three parameters computing the expected maximum hail size, the expected maximum hail size is close to the actual one.
An enhanced hail detection algorithm (HDA) for the CINRAD/SA radar replaced the original hail algorithm in 2004. The new HDA can estimate the probability of hail (POH, any size), severe hail (diameter greater that 19 mm), and expected maximumsize hail for each detected storm cell. The performance of POH detection is evaluated with Jinan's CINRAD/SA data, using 50% as the warning threshold for the POH parameter, and the verification against hail observations of any size is conducted, and the following accuracy measures are obtained: POD (Probability Of Detection) is 100%, FAR (Falas Alarm Ratio) is 72.2%，CSI (Critical Success Index) is 88%. The expected maximum hail size is 14.6 mm bigger than the actual maximum hail size averagely. Using JinanCINRAD/SA data of 2001 to 2005, the distributive characteristics of the maximum reflectivity in the cases of convective clouds are analyzed. The maximum reflectivities are 59.7, 61.8, 63.9 dBz for hailstorms and 53.8, 54.9, 55.6 dBz for nonhail storms in May, June and July, respectively. So the minimum and maximum reflectivities of a component used in the calculation of the probability of hail are modulated from 45 to 53 dBz, and FAR and CSI are improved obviously. Through adjusting three parameters computing the expected maximum hail size, the expected maximum hail size is close to the actual one.
2007, 35(5):732-735.
Abstract:
An introduction is made to the dual channel, the dual channel consistency, the basic requirements for dual channel amplitude consistency and dual channel phase consistency, as well as the factors and critical devices influencing dual channel consistency. The impacts of the dual channel inconsistency on radar measuring performance (including measuring errors in differential reflectivity, differential propagation phase, differential propagation phase, and specially designated differential propagation phase) are studied.
An introduction is made to the dual channel, the dual channel consistency, the basic requirements for dual channel amplitude consistency and dual channel phase consistency, as well as the factors and critical devices influencing dual channel consistency. The impacts of the dual channel inconsistency on radar measuring performance (including measuring errors in differential reflectivity, differential propagation phase, differential propagation phase, and specially designated differential propagation phase) are studied.
2007, 35(5):736-739.
Abstract:
The performance of radar's klystron affects directly the quality of radar echoes and operating cost, so the proper use and aintenance of klystrons are paid increasing attention presently. Taking the CINRAD/CC radar at the Dehong Meteorological Bureau as an example, some useful hints in operation and maintenance of radar klystrons are summarized. According to the needs of the operational service, some new indexes and suggestions on the operation, maintenance, and working state control of radar klystrons are presented in combination with working experiences, which may be helpful to the other types of CINRAD radar.
The performance of radar's klystron affects directly the quality of radar echoes and operating cost, so the proper use and aintenance of klystrons are paid increasing attention presently. Taking the CINRAD/CC radar at the Dehong Meteorological Bureau as an example, some useful hints in operation and maintenance of radar klystrons are summarized. According to the needs of the operational service, some new indexes and suggestions on the operation, maintenance, and working state control of radar klystrons are presented in combination with working experiences, which may be helpful to the other types of CINRAD radar.
2007, 35(5):740-743.
Abstract:
Cloud mask is the most important step in studying the effect of clouds on the climate system with satellite data. In order to identify AIRS cloud mask with MODIS cloud mask products objectively, the Nagle's common space matching algorithm is adopted on the basis of scanning geometric characteristics. It is a practical application to combine highspatial resolution products with highspectral resolution detecting images. The key steps for synergistic use of imager and sounder radiance measurements are the collocation in space and time and the determination of the cloud mask products within the sensor's pixel. With the combined MODISAIRS data, the determination can be made of not only AIRS cloud mask, but also cloud phase, effective cloud amount, cloud optical thickness, etc.
Cloud mask is the most important step in studying the effect of clouds on the climate system with satellite data. In order to identify AIRS cloud mask with MODIS cloud mask products objectively, the Nagle's common space matching algorithm is adopted on the basis of scanning geometric characteristics. It is a practical application to combine highspatial resolution products with highspectral resolution detecting images. The key steps for synergistic use of imager and sounder radiance measurements are the collocation in space and time and the determination of the cloud mask products within the sensor's pixel. With the combined MODISAIRS data, the determination can be made of not only AIRS cloud mask, but also cloud phase, effective cloud amount, cloud optical thickness, etc.
2007, 35(5):744-749.
Abstract:
The homogeneity test of annual mean temperature series is carried out using annual mean temperature over Shandong Province from 1961 to 2005 by means of the regressive method. Through the contrastive analysis of the historical information about meteorological station, it is found that the regressive method can be applied to the homogeneity test on the annual mean temperature series with the significance level being 0.01. The results show that the relocation, environment, observational instrument type or observation time of stations have direct effects on the continuity of observational records and the homogeneity of climatological data. Especially, the change of observation station location is the most important factor.
The homogeneity test of annual mean temperature series is carried out using annual mean temperature over Shandong Province from 1961 to 2005 by means of the regressive method. Through the contrastive analysis of the historical information about meteorological station, it is found that the regressive method can be applied to the homogeneity test on the annual mean temperature series with the significance level being 0.01. The results show that the relocation, environment, observational instrument type or observation time of stations have direct effects on the continuity of observational records and the homogeneity of climatological data. Especially, the change of observation station location is the most important factor.
2007, 35(5):750-754.
Abstract:
In order to compare the difference between Lband and 59701 upperair sounding systems, an analysis is made of the temperature, pressure, and humidity data of Hangzhou for a whole month by mean of the deviation and mean square deviation methods. The results indicate that compared with the 59701 sounding system, the temperature and height data from the Lband sounding system are more stable and less discrete, which is favorable to the improvement of weather forecasting. There exists a distinct inflexion point at 70 hPa in temperature difference between the two sounding systems, and the reason remains to be studied further.
In order to compare the difference between Lband and 59701 upperair sounding systems, an analysis is made of the temperature, pressure, and humidity data of Hangzhou for a whole month by mean of the deviation and mean square deviation methods. The results indicate that compared with the 59701 sounding system, the temperature and height data from the Lband sounding system are more stable and less discrete, which is favorable to the improvement of weather forecasting. There exists a distinct inflexion point at 70 hPa in temperature difference between the two sounding systems, and the reason remains to be studied further.
2007, 35(5):755-758.
Abstract:
The Longyan shortterm disaster weather warning system aims to improve the accuracy, effectiveness, and pertinence of warning messages with the features of automatic warning at multiple levels, quickly composing, and timely releasing of warning messages. According to the needs of the local economy development and disaster prevention and mitigation, the system can make quickly visualized meteorological SMS (Short Message Service) with electronic maps, radar products, and regional automatic weather station data combined, which can be directly released to multilevel users through mobile phones. Through the classification and processing of user information according to GIS data, the system has the characteristics of efficient, visualized, geographically pertinent, flexible, timely, and satisfactory coverage.
The Longyan shortterm disaster weather warning system aims to improve the accuracy, effectiveness, and pertinence of warning messages with the features of automatic warning at multiple levels, quickly composing, and timely releasing of warning messages. According to the needs of the local economy development and disaster prevention and mitigation, the system can make quickly visualized meteorological SMS (Short Message Service) with electronic maps, radar products, and regional automatic weather station data combined, which can be directly released to multilevel users through mobile phones. Through the classification and processing of user information according to GIS data, the system has the characteristics of efficient, visualized, geographically pertinent, flexible, timely, and satisfactory coverage.
2007, 35(5):759-760.
Abstract:
The data processing and operation monitoring subsystem of DCS (Data Collection System) mainly focuses on the unpacking and data checking of packaged datagram and DCP (Data Collection Platform) information through the highspeed network with CDAS (Commander Data Acquired System). The system can generate realtime DCP messages and classified DCPstatus information, realizing DCP operating status monitoring, and meanwhile input all categories of data into the database, thereby to provide DCP users with relevant data for the distributing and broadcasting of DCP datagram. This system is developed by means of software engineering with a modularized structure. Through the more than a half year trial operation and continual betterment, it is proved stable and reliable.
The data processing and operation monitoring subsystem of DCS (Data Collection System) mainly focuses on the unpacking and data checking of packaged datagram and DCP (Data Collection Platform) information through the highspeed network with CDAS (Commander Data Acquired System). The system can generate realtime DCP messages and classified DCPstatus information, realizing DCP operating status monitoring, and meanwhile input all categories of data into the database, thereby to provide DCP users with relevant data for the distributing and broadcasting of DCP datagram. This system is developed by means of software engineering with a modularized structure. Through the more than a half year trial operation and continual betterment, it is proved stable and reliable.
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.