Volume 43,Issue 2,2015 Table of Contents
2015, 43(2):175-180.
Abstract:
Five calibration methods of pyranometers are introduced and their advantages and disadvantages are compared. For different classes of pyranometers, there are different calibration methods to transfer values in order to meet the needs of different customers. By comparison of different methods, the results show that the sensitivity accuracy of the pyranometers calibrated by the shaded/unshaded method is better than those by using the component summation technique. Likewise, the component summation method is better than the sidebyside comparison method. The error of the method using an artificial source to calibrate pyranometers in the laboratory is the maxmium. According to WMO CIMO Guide, pyranometers should be calibrated only in the position of using sun as light source. The shaded/unshaded method is used to calibrate the national diffuse irradiance standard pyranometer, and the component summation method to calibrate the provincial standard pyranometer, the side by side comparison method to calibrate the working pyranometer in stations. All these methods ensure the accuracy and reliability of solar radiation measurement data.
Five calibration methods of pyranometers are introduced and their advantages and disadvantages are compared. For different classes of pyranometers, there are different calibration methods to transfer values in order to meet the needs of different customers. By comparison of different methods, the results show that the sensitivity accuracy of the pyranometers calibrated by the shaded/unshaded method is better than those by using the component summation technique. Likewise, the component summation method is better than the sidebyside comparison method. The error of the method using an artificial source to calibrate pyranometers in the laboratory is the maxmium. According to WMO CIMO Guide, pyranometers should be calibrated only in the position of using sun as light source. The shaded/unshaded method is used to calibrate the national diffuse irradiance standard pyranometer, and the component summation method to calibrate the provincial standard pyranometer, the side by side comparison method to calibrate the working pyranometer in stations. All these methods ensure the accuracy and reliability of solar radiation measurement data.
2015, 43(2):181-185.
Abstract:
Tests of supply voltages and load resistances on several PTB220 pressure sensors are carried out for the accuracy and reliability of verification results. The test results show that the measurement errors of pressure sensor analog output are increasing gradually with the increasing supply voltage in the range of 12 to 30 V. The maximum error variation is up to －028 hPa, while there is no effect for digital outputs. The analog measurement errors of the PTB220 pressure sensors are increasing with the increasing of load resistance at the low limit of pressure measurement range for load resistance variation between 10 kΩ and 500 kΩ. Based on this finding, suggestions for the modification of verification method of PTB220 pressure sensors are proposed accordingly.
Tests of supply voltages and load resistances on several PTB220 pressure sensors are carried out for the accuracy and reliability of verification results. The test results show that the measurement errors of pressure sensor analog output are increasing gradually with the increasing supply voltage in the range of 12 to 30 V. The maximum error variation is up to －028 hPa, while there is no effect for digital outputs. The analog measurement errors of the PTB220 pressure sensors are increasing with the increasing of load resistance at the low limit of pressure measurement range for load resistance variation between 10 kΩ and 500 kΩ. Based on this finding, suggestions for the modification of verification method of PTB220 pressure sensors are proposed accordingly.
2015, 43(2):186-190.
Abstract:
The collectors of automatic weather stations are damaged mostly by collector faults through wind sensors induced by lightning. The best way to solve this problem is to disconnect the physical connection (signal line and power line) of the wind sensor and collector, on condition that the data is surely collected. An opticalfiber wind signal isolator is design for automatic weather stations, which transits wind signals from the wind sensor to collector by means of EDA technology, and in which the wind sensor is powered by the lightning protection power. The tests show that this transmitter can not only protect the collector against lightning, but also guarantee data collecting, and has good promotion and application value.
The collectors of automatic weather stations are damaged mostly by collector faults through wind sensors induced by lightning. The best way to solve this problem is to disconnect the physical connection (signal line and power line) of the wind sensor and collector, on condition that the data is surely collected. An opticalfiber wind signal isolator is design for automatic weather stations, which transits wind signals from the wind sensor to collector by means of EDA technology, and in which the wind sensor is powered by the lightning protection power. The tests show that this transmitter can not only protect the collector against lightning, but also guarantee data collecting, and has good promotion and application value.
2015, 43(2):191-195.
Abstract:
The analysis and processing of the overcurrent protection faults in IGBT (a common switch in CINRAD/SA radar transmitters), are described. As the fault alarm has no sign in the CINRAD/SA radar transmitter alarm panel, the troubleshooting is difficult. The overcurrent of the switch IGBT is monitored by its chip EXB841, and the overcurrent protection is conducted according to the over current signal outputs to cut off the drive signal outputs timely. Through the analysis of the flow condition monitored by EXB841 and alarms when faults occur, it is found that charging circuit faults of CINRAD/SA radar transmitter are the main cause of the IGBT overcurrent protection. The charging circuit faults result in the sudden current change of primary transformers and IGBTs,leading to the L〖SX(〗di〖〗dt〖SX)〗 changes in inductive voltage at both ends, the reverse electric potential difference between the IGBT C and E, the fast turnon diode cutoff, the overcurrent in EXB841 monitoring, and the quick cutoff of IGBT, as well as IGBT of the protection switch component.
The analysis and processing of the overcurrent protection faults in IGBT (a common switch in CINRAD/SA radar transmitters), are described. As the fault alarm has no sign in the CINRAD/SA radar transmitter alarm panel, the troubleshooting is difficult. The overcurrent of the switch IGBT is monitored by its chip EXB841, and the overcurrent protection is conducted according to the over current signal outputs to cut off the drive signal outputs timely. Through the analysis of the flow condition monitored by EXB841 and alarms when faults occur, it is found that charging circuit faults of CINRAD/SA radar transmitter are the main cause of the IGBT overcurrent protection. The charging circuit faults result in the sudden current change of primary transformers and IGBTs,leading to the L〖SX(〗di〖〗dt〖SX)〗 changes in inductive voltage at both ends, the reverse electric potential difference between the IGBT C and E, the fast turnon diode cutoff, the overcurrent in EXB841 monitoring, and the quick cutoff of IGBT, as well as IGBT of the protection switch component.
2015, 43(2):196-201.
Abstract:
Radar echo signals inevitably contain noise, and the presence of noise seriously interferes with the accurate analysis of radar echo signals. In order to improve the signal to noise ratio of radar echoes, the wavelet analysis is used to determine the wavelet function, the number of decomposition levels, the thresholds, and threshold quantization through experimental analysis. The results show that the wavelet analysis denoising method can effectively suppress the noises superimposed on radar echo signals, and the signal to noise ratio of radar echoes significantly increased after denoising, which is highly applicable.
Radar echo signals inevitably contain noise, and the presence of noise seriously interferes with the accurate analysis of radar echo signals. In order to improve the signal to noise ratio of radar echoes, the wavelet analysis is used to determine the wavelet function, the number of decomposition levels, the thresholds, and threshold quantization through experimental analysis. The results show that the wavelet analysis denoising method can effectively suppress the noises superimposed on radar echo signals, and the signal to noise ratio of radar echoes significantly increased after denoising, which is highly applicable.
2015, 43(2):202-206.
Abstract:
Operational tests are conducted for measurements from 20 soilmoisture automatic stations which were built in 2010 in Yunnan, based on the related operational verification standards. Among the 20 automatic stations, 17 passed the operational tests. In order to assess the data quality of the passed stations, a comparative analysis is made between manual and automatic observation data. Since verification was conducted mostly during rainy season, the standard deviations of observation samples are usually small, which leads to large errors during dry season afterwards between manual and automatic observation. The absolute errors of volumetric soil water are converted into soil relative humidity errors, and it is found that the number of error values with soil relative humidity above 10% accounts for 241% of total number in effective verifications; and the number of ones under 6% make up only 426% of total number. It is considered that the current evaluation criteria of the operational tests for soilmoisture automatic stations are worth of further discussion and argument.
Operational tests are conducted for measurements from 20 soilmoisture automatic stations which were built in 2010 in Yunnan, based on the related operational verification standards. Among the 20 automatic stations, 17 passed the operational tests. In order to assess the data quality of the passed stations, a comparative analysis is made between manual and automatic observation data. Since verification was conducted mostly during rainy season, the standard deviations of observation samples are usually small, which leads to large errors during dry season afterwards between manual and automatic observation. The absolute errors of volumetric soil water are converted into soil relative humidity errors, and it is found that the number of error values with soil relative humidity above 10% accounts for 241% of total number in effective verifications; and the number of ones under 6% make up only 426% of total number. It is considered that the current evaluation criteria of the operational tests for soilmoisture automatic stations are worth of further discussion and argument.
2015, 43(2):207-210.
Abstract:
According to the verification regulation corresponding to temperature and rainfall of automatic meteorological stations, the rationality of the related indicators and rules is discussed. The purpose is to make verification regulation more perfect and reasonable. The error structure is analyzed, and the deduced theoretical formula is given from the characteristics of the instrument itself, combined with the actual work experiences. As a result, it is found that the temperature (ground temperature) and rainfall measuring performance requirements of the maximum permissible error and resolution are unreasonable. The maximum permissible errors of temperature and rainfall are obtained from the error formulas. Some suggestions about the determination of the indicators in the regulation are proposed.
According to the verification regulation corresponding to temperature and rainfall of automatic meteorological stations, the rationality of the related indicators and rules is discussed. The purpose is to make verification regulation more perfect and reasonable. The error structure is analyzed, and the deduced theoretical formula is given from the characteristics of the instrument itself, combined with the actual work experiences. As a result, it is found that the temperature (ground temperature) and rainfall measuring performance requirements of the maximum permissible error and resolution are unreasonable. The maximum permissible errors of temperature and rainfall are obtained from the error formulas. Some suggestions about the determination of the indicators in the regulation are proposed.
2015, 43(2):211-215.
Abstract:
There exist some common problems in the backbone network of provincial meteorological services. The loadsharing, for example, has not been achieved in different network lines, so that the backup line is often idle, and the asymmetric routing between provinces and cities has an effect on remote video conference service. There is no control of bandwidths for different tasks, and there are mutual influences among different tasks. Some technical means are proposed aiming at above problems. Through introducing the policy routing to shunt data transmission, the benefits of multiple lines are improved, so the loadsharing is realized, and the problem of asymmetric routing is solved, so that the effect of video conference is guaranteed. The occupied bandwidth of different tasks on lines is managed by introducing a series of QoS strategies, which can not only ensure the bandwidth of key tasks such as realtime data transmission and video conference, but also provide dynamic bandwidth resources for other tasks, thus to make full use of the existing network bandwidth. A series of tests indicates that the optimization and upgrade of the entire network has reached the design target, which provides a good reference for the network design of other departments.
There exist some common problems in the backbone network of provincial meteorological services. The loadsharing, for example, has not been achieved in different network lines, so that the backup line is often idle, and the asymmetric routing between provinces and cities has an effect on remote video conference service. There is no control of bandwidths for different tasks, and there are mutual influences among different tasks. Some technical means are proposed aiming at above problems. Through introducing the policy routing to shunt data transmission, the benefits of multiple lines are improved, so the loadsharing is realized, and the problem of asymmetric routing is solved, so that the effect of video conference is guaranteed. The occupied bandwidth of different tasks on lines is managed by introducing a series of QoS strategies, which can not only ensure the bandwidth of key tasks such as realtime data transmission and video conference, but also provide dynamic bandwidth resources for other tasks, thus to make full use of the existing network bandwidth. A series of tests indicates that the optimization and upgrade of the entire network has reached the design target, which provides a good reference for the network design of other departments.
2015, 43(2):216-220.
Abstract:
Considering the requirements of provincial public meteorological service system, combined with the existing meteorological service products and information networks in Sichuan Province，the overall architecture design of provincial public weather services system is proposed, which uses the advanced network service technology, including the integration of provinceprefecturecounty basic service products, the production of the specialised products, the classification of clients, and so on. This system aims to enhance this design as a universal model across China and provides a reference for this industry by means of the construction and application of public meteorological service system in Sichuan Province. The system has put to use in June 2013, and the application indicates that it has high efficiency, relability, utilization efficiency, and practicality. The model of the meteorological service system is applied in Yunnan Meteorological Service.
Considering the requirements of provincial public meteorological service system, combined with the existing meteorological service products and information networks in Sichuan Province，the overall architecture design of provincial public weather services system is proposed, which uses the advanced network service technology, including the integration of provinceprefecturecounty basic service products, the production of the specialised products, the classification of clients, and so on. This system aims to enhance this design as a universal model across China and provides a reference for this industry by means of the construction and application of public meteorological service system in Sichuan Province. The system has put to use in June 2013, and the application indicates that it has high efficiency, relability, utilization efficiency, and practicality. The model of the meteorological service system is applied in Yunnan Meteorological Service.
2015, 43(2):221-225.
Abstract:
In order to overcome the shortage of computer resources, the difficulties in computer maintenance, big data sharing needs in countylevel meteorological service, and problems in the resource integration, the Beijing Meteorological Service established a virtual server cluster and virtual desktop based on virtual technology. The results show that users in countylevel meteorological service can access MICAPS (Meteorological Information Comprehensive Analysis and Process System) and VIPS (Veryshortrange Interactive Prediction System) in the municipal meteorological service, and other library resources in the China Meteorological Administration through a virtual desktop by lowerbandwidth. The virtual server cluster created by the Beijing Meteorological Service is effectively to meet the rapidgrowting demand of server resources. It can be seen that virtualization technology is necessary for the optimization and improvement of information technological resources in the meteorological department.
In order to overcome the shortage of computer resources, the difficulties in computer maintenance, big data sharing needs in countylevel meteorological service, and problems in the resource integration, the Beijing Meteorological Service established a virtual server cluster and virtual desktop based on virtual technology. The results show that users in countylevel meteorological service can access MICAPS (Meteorological Information Comprehensive Analysis and Process System) and VIPS (Veryshortrange Interactive Prediction System) in the municipal meteorological service, and other library resources in the China Meteorological Administration through a virtual desktop by lowerbandwidth. The virtual server cluster created by the Beijing Meteorological Service is effectively to meet the rapidgrowting demand of server resources. It can be seen that virtualization technology is necessary for the optimization and improvement of information technological resources in the meteorological department.
2015, 43(2):226-231.
Abstract:
Concerning the development of threedimensional GIS application and the higher demands in visualization of meteorological service in the efficient policymaking support, a method of developing threedimensional meteorological GIS with independent intellectual property rights is presented. A description is made from the design of system, functions, data accessing, components, and the implementation technology of meteorological data organization, meteorological plotting, and 2D and 3D meteorological data drawing. The system can efficiently load massive twodimensional and threedimensional meteorological data, and support meteorological plotting, analysis, and other functions. The platform runs steadily and has outstanding visual effect. It is useful for meteorological data process, numerical weather prediction, meteorological simulation and other meteorological services.
Concerning the development of threedimensional GIS application and the higher demands in visualization of meteorological service in the efficient policymaking support, a method of developing threedimensional meteorological GIS with independent intellectual property rights is presented. A description is made from the design of system, functions, data accessing, components, and the implementation technology of meteorological data organization, meteorological plotting, and 2D and 3D meteorological data drawing. The system can efficiently load massive twodimensional and threedimensional meteorological data, and support meteorological plotting, analysis, and other functions. The platform runs steadily and has outstanding visual effect. It is useful for meteorological data process, numerical weather prediction, meteorological simulation and other meteorological services.
2015, 43(2):232-235.
Abstract:
In order to better use of digitized historical meteorological archives, a retrieval platform of meteorological digital archive is built within the meteorological network based on .Net, which uses the MD5 algorithm to encrypt user login passwords and digital archive file names, can effectively protect the user’s password information and shield the naming rules of digital files, as well as keep track of user behavior management, along with the scaling operation of images in digital archives in Flash. The platform can retrieve different types of historical meteorological digital archives, effectively improve availability and service of meteorological digital archives, and promote the digital information sharing transformation of meteorological digital archive service.
In order to better use of digitized historical meteorological archives, a retrieval platform of meteorological digital archive is built within the meteorological network based on .Net, which uses the MD5 algorithm to encrypt user login passwords and digital archive file names, can effectively protect the user’s password information and shield the naming rules of digital files, as well as keep track of user behavior management, along with the scaling operation of images in digital archives in Flash. The platform can retrieve different types of historical meteorological digital archives, effectively improve availability and service of meteorological digital archives, and promote the digital information sharing transformation of meteorological digital archive service.
2015, 43(2):236-239.
Abstract:
A new automatic weather station, which is capable to add new sensors, is developed based on the advanced CAN technology. The software, hardware, lightning protection, processing speed, and storage capacity of the new automatic weather station are improved. Developed from the operational software OSSMO 2004, the new version OSSMO 2010 is stable, flexible, extensible, and usable. Aiming to discuss differences between the two versions, comparison ansd analysis are conducted. Some changes in parameter settings, data files, radiation and evaporation data maintenance in OSSMO 2010 are made, and the data processing of OSSMO 2010 is the same as OSSMO 2004 Using this method, the seamless integration of observation can be realized. The particular differences and processing methods of the software are discussed, which is useful for observers in stations to be familiar with OSSMO 2010 quickly.
A new automatic weather station, which is capable to add new sensors, is developed based on the advanced CAN technology. The software, hardware, lightning protection, processing speed, and storage capacity of the new automatic weather station are improved. Developed from the operational software OSSMO 2004, the new version OSSMO 2010 is stable, flexible, extensible, and usable. Aiming to discuss differences between the two versions, comparison ansd analysis are conducted. Some changes in parameter settings, data files, radiation and evaporation data maintenance in OSSMO 2010 are made, and the data processing of OSSMO 2010 is the same as OSSMO 2004 Using this method, the seamless integration of observation can be realized. The particular differences and processing methods of the software are discussed, which is useful for observers in stations to be familiar with OSSMO 2010 quickly.
2015, 43(2):240-243.
Abstract:
Concerning the problem that some special uplink data cannot directly access the provinciallevel new generation meteorological communication system, the Meteorological Information Monitoring Platform (MIMP) of Hubei Province is developed. The implementation technology of the MIMP system and the uplink data processing and transmission process of GPS/MET, lightning, regional stations, and automatic soil moisture are introduced. The MIMP makes up the deficiency of the provinciallevel new generation meteorological communication systems and has become an indispensable part of the provincial center of information transmission in Hubei.
Concerning the problem that some special uplink data cannot directly access the provinciallevel new generation meteorological communication system, the Meteorological Information Monitoring Platform (MIMP) of Hubei Province is developed. The implementation technology of the MIMP system and the uplink data processing and transmission process of GPS/MET, lightning, regional stations, and automatic soil moisture are introduced. The MIMP makes up the deficiency of the provinciallevel new generation meteorological communication systems and has become an indispensable part of the provincial center of information transmission in Hubei.
2015, 43(2):244-249.
Abstract:
Based on the hazardous weather reports, disaster telegraph data and NCEP 1°×1° reanalysis data from 175 stations in the Beijing, Tianjin and Hebei (HTB) areas from May to September from 2001 to 2008, the synoptic circulation patterns in the HTB area from May to September, which is objectively divided into four types by using the SelfOrganizing Maps (SOM) method, are identified, and the synoptic characteristics and main severe convective weather types of each synoptic pattern are analyzed. The results indicate that: (1) There are four cluster types of synoptic patterns in the BTH area: the Warm and Wet (WWS) pattern, in which shorttime rainstorms occur mainly in July and August; the Cold Vortex (CV) pattern, in which hails accompanied by shorttime rainstorms and gales occur mainly in June and July; the Northwest Airflow (NA) pattern, in which gales occur mainly in May; and the West Wind Trough (WWT) pattern, in which gales and shorttime rainstorms occur mainly in June and September. （2）The main features of the WWS pattern include warm and humid at low levels, superimposed by dry and cold northwest flow, sufficient water vapor transmission, and strong stratification instability； the main features of the CV pattern include the strong inrush of arid cold air in the middlehigh layer from a stronger northerly airflow and good moisture condition at low levels; the main features of the NA pattern include the strong inrush of arid cold air in the middlehigh layer and strong vertical wind shear； the features of the WWT pattern are not obvious. （3）The NA and CV patterns have the highest frequency of severe convective weather, more than 65%, and the WWS pattern comes second, followed by WWT pattern.
Based on the hazardous weather reports, disaster telegraph data and NCEP 1°×1° reanalysis data from 175 stations in the Beijing, Tianjin and Hebei (HTB) areas from May to September from 2001 to 2008, the synoptic circulation patterns in the HTB area from May to September, which is objectively divided into four types by using the SelfOrganizing Maps (SOM) method, are identified, and the synoptic characteristics and main severe convective weather types of each synoptic pattern are analyzed. The results indicate that: (1) There are four cluster types of synoptic patterns in the BTH area: the Warm and Wet (WWS) pattern, in which shorttime rainstorms occur mainly in July and August; the Cold Vortex (CV) pattern, in which hails accompanied by shorttime rainstorms and gales occur mainly in June and July; the Northwest Airflow (NA) pattern, in which gales occur mainly in May; and the West Wind Trough (WWT) pattern, in which gales and shorttime rainstorms occur mainly in June and September. （2）The main features of the WWS pattern include warm and humid at low levels, superimposed by dry and cold northwest flow, sufficient water vapor transmission, and strong stratification instability； the main features of the CV pattern include the strong inrush of arid cold air in the middlehigh layer from a stronger northerly airflow and good moisture condition at low levels; the main features of the NA pattern include the strong inrush of arid cold air in the middlehigh layer and strong vertical wind shear； the features of the WWT pattern are not obvious. （3）The NA and CV patterns have the highest frequency of severe convective weather, more than 65%, and the WWS pattern comes second, followed by WWT pattern.
2015, 43(2):250-260.
Abstract:
Using the conventional meteorological data, automatic weather station data, SWAN (Sever Weather Automatically Nowcast System) products, and radar PUP products from the radar over the Sichuan basin, the evolution characteristics of radar echoes and the train effect of lineshaped (banded) echoes for 35 regional rain storms from 2010 to 2013 are analyzed by the statistical method. Results show that initial echoes form usually along the mountain areas at the edge of the basin in the afternoon or before midnight under the influence of topography and 850 hPa winds. The peak period of echo formation is 16:00 to 19:00 The formation mechanisms of lineshaped (banded) and massive echoes in the Sichuan basin are revealed. The heavy rain conceptual models are built for the west, north and southcentral parts of the Sichuan basin. It is the best time to release rainstorm warnings when the echoes become lineshaped (banded) or massive. The accuracy of rainstorm area warning is satisfactory, with the average warning lead time being 5 to 8 hours.
Using the conventional meteorological data, automatic weather station data, SWAN (Sever Weather Automatically Nowcast System) products, and radar PUP products from the radar over the Sichuan basin, the evolution characteristics of radar echoes and the train effect of lineshaped (banded) echoes for 35 regional rain storms from 2010 to 2013 are analyzed by the statistical method. Results show that initial echoes form usually along the mountain areas at the edge of the basin in the afternoon or before midnight under the influence of topography and 850 hPa winds. The peak period of echo formation is 16:00 to 19:00 The formation mechanisms of lineshaped (banded) and massive echoes in the Sichuan basin are revealed. The heavy rain conceptual models are built for the west, north and southcentral parts of the Sichuan basin. It is the best time to release rainstorm warnings when the echoes become lineshaped (banded) or massive. The accuracy of rainstorm area warning is satisfactory, with the average warning lead time being 5 to 8 hours.
2015, 43(2):261-269.
Abstract:
The temporal and spatial distributions, circulation patterns and physical quantities of hails in Guangdong in Recent 10 years are analyzed. In Guangdong, hail weather occurs mostly in March, April and May, and hails occurred more frequently in the northern Guangdong and the Xijiang River region. The typical circulation patterns of hails can be divided into three types: cold front with trough (typeⅠ), warm zoon (typeⅡ), and elevated thunderstorms (type Ⅲ). Most severe hails happened in typeⅠ; that is，the cold front accompanies with the lowlevel shear line (vortex) and upper trough (temperature trough), and the surface cold air and the intrusion of temperature trough at upper levels make the atmosphere unstable. Severe convective weather is driven by the cold front, shear line, and trough, and the locations of hails in typeⅠare usually in front of the upperlevel trough, near the cold front and shear line. In typeⅡ, there is no cold front to the south of the Yangtze River on surface, and there is a convergence region of southeasterly and southerly at low levels over Guangdong. The drycold air brought by the upperlevel trough overlaps over the warmmoist air, leading to unstable stratification. The locations of hails in typeⅡare usually in the convergence region in front of the trough. In type Ⅲ, Guangdong is behind a cold front, and there is a lowlevel temperature inversion, and warm and moist air lifting convectively above the temperature inversion. The locations of hails in type Ⅲ are often near the shear line and hails are generally small.The mean environmental physical quantities favorable for severe hails are: the height of 0 ℃ is 4505 m; the height of －20 ℃ is 7632 m; Kindex is 35 ℃; SIindex is －099 ℃; the vertical wind shear is 267×10-3 s-1; the pressure vertical velocity is －28×10-2Pa/s; differential temperature advection between 400 hPa and 700 hPa is －239×10-5℃/s. Severe hails require larger Kindex, vertical wind shear, vertical velocity, differential temperature advection, more water vapor supply and smaller SIindex.
The temporal and spatial distributions, circulation patterns and physical quantities of hails in Guangdong in Recent 10 years are analyzed. In Guangdong, hail weather occurs mostly in March, April and May, and hails occurred more frequently in the northern Guangdong and the Xijiang River region. The typical circulation patterns of hails can be divided into three types: cold front with trough (typeⅠ), warm zoon (typeⅡ), and elevated thunderstorms (type Ⅲ). Most severe hails happened in typeⅠ; that is，the cold front accompanies with the lowlevel shear line (vortex) and upper trough (temperature trough), and the surface cold air and the intrusion of temperature trough at upper levels make the atmosphere unstable. Severe convective weather is driven by the cold front, shear line, and trough, and the locations of hails in typeⅠare usually in front of the upperlevel trough, near the cold front and shear line. In typeⅡ, there is no cold front to the south of the Yangtze River on surface, and there is a convergence region of southeasterly and southerly at low levels over Guangdong. The drycold air brought by the upperlevel trough overlaps over the warmmoist air, leading to unstable stratification. The locations of hails in typeⅡare usually in the convergence region in front of the trough. In type Ⅲ, Guangdong is behind a cold front, and there is a lowlevel temperature inversion, and warm and moist air lifting convectively above the temperature inversion. The locations of hails in type Ⅲ are often near the shear line and hails are generally small.The mean environmental physical quantities favorable for severe hails are: the height of 0 ℃ is 4505 m; the height of －20 ℃ is 7632 m; Kindex is 35 ℃; SIindex is －099 ℃; the vertical wind shear is 267×10-3 s-1; the pressure vertical velocity is －28×10-2Pa/s; differential temperature advection between 400 hPa and 700 hPa is －239×10-5℃/s. Severe hails require larger Kindex, vertical wind shear, vertical velocity, differential temperature advection, more water vapor supply and smaller SIindex.
2015, 43(2):270-275.
Abstract:
By means of the observation data of the Golmud weather station from 1961 to 2012, the characteristics and impact factors of scattered radiation are studied. It is proved that scattered radiation showed a significant decreasing trend at Golmud in 52 years with a decrease rate of 9837 MJ/m2 per 10 years （〖WTBX〗P〖WTBZ〗<005）; the scattered radiation curve shows a unimodal trend with the annual maximum being 33332 MJ/m2, accounting for 13% in the annual total, and the minimum being 10835 MJ/m2， accounting for 4% in the annual total. The annual mean of scattered radiation is 261485 MJ/m2, accounting for 38% in the annual global radiation. The amount of scattered radiation in summer (1467 MJ/m2) is 22 times as great as that in winter (654 MJ/m2); the daily change curve of scattered radiation shows also a unimodal trend. The maximum appears around noon, and scattered radiation increases with the total cloud cover; the maximum appears along with cirrostratus and the minimum with cumulus; scattered radiation increases with the increase of solar elevation when there is snow, and the influence of ground snow cover on scattering radiation is mainly due to the increase of the scattered radiation reaching the ground induced by the multiple reflection on the surface and in the atmosphere.
By means of the observation data of the Golmud weather station from 1961 to 2012, the characteristics and impact factors of scattered radiation are studied. It is proved that scattered radiation showed a significant decreasing trend at Golmud in 52 years with a decrease rate of 9837 MJ/m2 per 10 years （〖WTBX〗P〖WTBZ〗<005）; the scattered radiation curve shows a unimodal trend with the annual maximum being 33332 MJ/m2, accounting for 13% in the annual total, and the minimum being 10835 MJ/m2， accounting for 4% in the annual total. The annual mean of scattered radiation is 261485 MJ/m2, accounting for 38% in the annual global radiation. The amount of scattered radiation in summer (1467 MJ/m2) is 22 times as great as that in winter (654 MJ/m2); the daily change curve of scattered radiation shows also a unimodal trend. The maximum appears around noon, and scattered radiation increases with the total cloud cover; the maximum appears along with cirrostratus and the minimum with cumulus; scattered radiation increases with the increase of solar elevation when there is snow, and the influence of ground snow cover on scattering radiation is mainly due to the increase of the scattered radiation reaching the ground induced by the multiple reflection on the surface and in the atmosphere.
2015, 43(2):276-282.
Abstract:
Guangdong suffered the heaviest continuous torrential rainfall from 13 to 17 December 2013, according to the winter records since 1951 Based on the data of conventional meteorological observation, automatic weather station, and NCEP reanalysis, the characteristics and the possible causes of the continuous torrential rain are analyzed. The results show that the circulation situation at middle and high levels in Asia shows a “ridge in north and trough in south” pattern, which was favorable for the southward moving of cold air and the persistent meeting with the moist southerly from the Bay of Bengal and the South China Sea, and resulted in an unusual local meridional circulation above Guangdong. There appeared intense divergence at upper levels and intense convergence at lower levels, a favorable condition for torrential rainfall. Compared with the continuous freezing rain and snow weather in Guangdong at the beginning of 2008, the meridional wavelength of the ridge and trough was larger, and the extension of the trough was farther south than normal; therefore, the cumulative precipitation in this event was stronger without freezing rainfall.
Guangdong suffered the heaviest continuous torrential rainfall from 13 to 17 December 2013, according to the winter records since 1951 Based on the data of conventional meteorological observation, automatic weather station, and NCEP reanalysis, the characteristics and the possible causes of the continuous torrential rain are analyzed. The results show that the circulation situation at middle and high levels in Asia shows a “ridge in north and trough in south” pattern, which was favorable for the southward moving of cold air and the persistent meeting with the moist southerly from the Bay of Bengal and the South China Sea, and resulted in an unusual local meridional circulation above Guangdong. There appeared intense divergence at upper levels and intense convergence at lower levels, a favorable condition for torrential rainfall. Compared with the continuous freezing rain and snow weather in Guangdong at the beginning of 2008, the meridional wavelength of the ridge and trough was larger, and the extension of the trough was farther south than normal; therefore, the cumulative precipitation in this event was stronger without freezing rainfall.
2015, 43(2):283-288.
Abstract:
Based on the conventional observational data and NECP/NCAR 1°×1° reanalysis data, a strong wind process happened over the Yellow and Bohai Seas on 5 and 6 December 2012 is analyzed. Results show that there were three phases: the largescale baric gradient wind caused by cold air and surface cyclone led to the gale; the surface allobaric field and its gradient resulted in rapidly increased wind speed during the initial stage; the greater the 3hour pressure change, the larger the allobaric gradient, the greater the change in wind speed. When the north wind prevailed, the positive gradient was consistent with wind direction, and the role of transforming speed growth was more obvious. The complement of highlevel cold advection and the diffusion of lower downstream cold advection have important influence on the course of the strong wind process.
Based on the conventional observational data and NECP/NCAR 1°×1° reanalysis data, a strong wind process happened over the Yellow and Bohai Seas on 5 and 6 December 2012 is analyzed. Results show that there were three phases: the largescale baric gradient wind caused by cold air and surface cyclone led to the gale; the surface allobaric field and its gradient resulted in rapidly increased wind speed during the initial stage; the greater the 3hour pressure change, the larger the allobaric gradient, the greater the change in wind speed. When the north wind prevailed, the positive gradient was consistent with wind direction, and the role of transforming speed growth was more obvious. The complement of highlevel cold advection and the diffusion of lower downstream cold advection have important influence on the course of the strong wind process.
2015, 43(2):289-294.
Abstract:
A heavy fog event with visibility less than 1000 meters covering most parts of Hinggan League on 21 and 22 October 2013 is analyzed. The conventional data on the MICAPS system, radiosonde data, and NCEP 25° × 25° reanalysis data are used to diagnose and analyze this fog process. The results show that: the foggy weather process lasted two days. The strongest fog occurred in the day time of 21 and 22 October with the minimum visibility less than 100 meters. The fog occursred in the southwest airflow at 500 hPa and the warm ridge at 850 hPa, and the forehead of a lowpressure field and a weak high pressure field are manifested on the ground. A stable existence of an inversion layer and southeast warm transportation provided favorable conditions for fog maintenance. The decreasing of ground humidity caused by the strong ascending air in the front of the highaltitude cold vortex is the main reason for the dissipation of the fog.
A heavy fog event with visibility less than 1000 meters covering most parts of Hinggan League on 21 and 22 October 2013 is analyzed. The conventional data on the MICAPS system, radiosonde data, and NCEP 25° × 25° reanalysis data are used to diagnose and analyze this fog process. The results show that: the foggy weather process lasted two days. The strongest fog occurred in the day time of 21 and 22 October with the minimum visibility less than 100 meters. The fog occursred in the southwest airflow at 500 hPa and the warm ridge at 850 hPa, and the forehead of a lowpressure field and a weak high pressure field are manifested on the ground. A stable existence of an inversion layer and southeast warm transportation provided favorable conditions for fog maintenance. The decreasing of ground humidity caused by the strong ascending air in the front of the highaltitude cold vortex is the main reason for the dissipation of the fog.
2015, 43(2):295-301.
Abstract:
Droughts are the main agrometeorological disasters during winter wheat growth periods, which seriously influence the growth and yields of winter wheat. Taking the winter wheat growing area of Anhui Province as an example, based on the daily meteorological data from 36 meteorological stations of the winter wheat area from 1960 to 2012, the Crop Water Deficit Index (CWDI), Comprehensive meteorological drought Index (CI), Standardized Precipitation Index (SPI) and Precipitation Anomaly percentage (PA) are calculated, and the four kinds of drought indices are compared and analyzed. The results show that PA and SPI are extremely consistent in crop growth season. The temporalspatial distributions of drought days calculated by the four drought indices are consistent in winter wheat growth season in total. SPI and PA indices have excellent stability of computation. However, they do not consider the expenditure of water, so that they are easy to exaggerate the level of drought； CI and CWDI indices take both recent rainfall situation and water balance into account, and can better characterize droughts. Considering the crop coefficient, CWDI can reveal the status of crop water deficiency and drought events in winter wheat growing season especially. In addition, according to correlation analysis between yield reduction rate and four drought indices, CWDI has better applicability in the monitoring and evaluation of drought development of winter wheat in Anhui.
Droughts are the main agrometeorological disasters during winter wheat growth periods, which seriously influence the growth and yields of winter wheat. Taking the winter wheat growing area of Anhui Province as an example, based on the daily meteorological data from 36 meteorological stations of the winter wheat area from 1960 to 2012, the Crop Water Deficit Index (CWDI), Comprehensive meteorological drought Index (CI), Standardized Precipitation Index (SPI) and Precipitation Anomaly percentage (PA) are calculated, and the four kinds of drought indices are compared and analyzed. The results show that PA and SPI are extremely consistent in crop growth season. The temporalspatial distributions of drought days calculated by the four drought indices are consistent in winter wheat growth season in total. SPI and PA indices have excellent stability of computation. However, they do not consider the expenditure of water, so that they are easy to exaggerate the level of drought； CI and CWDI indices take both recent rainfall situation and water balance into account, and can better characterize droughts. Considering the crop coefficient, CWDI can reveal the status of crop water deficiency and drought events in winter wheat growing season especially. In addition, according to correlation analysis between yield reduction rate and four drought indices, CWDI has better applicability in the monitoring and evaluation of drought development of winter wheat in Anhui.
2015, 43(2):302-308.
Abstract:
Based on the seasonal precipitation data from 1960 to 2010 in the southwestern Sichuan, combining the percentages of precipitation anomaly, the Copula method is applied to construct the hazard evaluation model of continuous droughts between adjacent seasons for each weather station in the southwestern Sichuan. The results indicate that the Copula function can be applied to construct the hazard evaluation model of continuous droughts between adjacent quarters at each station in the southwestern Sichuan. It is concluded:（1） the hazard degree of spring and summer continuous droughts is the lowest in the southwestern Sichuan, as low as 452% in Leshan.（2） the hazard degree of winter and spring continuous droughts is the highest， high up to 2899% in Panzhihua. （3） by contrast, the hazard degree of spring and summer continuous drought for Panzhihua is the highest, while the lowest in Leshan. For the same kind of continuous droughts, the risks for different stations are different. In general, when there are severe droughts in the adjacent seasons, the risk of continuous droughts is the lowest; when there are light droughts in the adjacent seasons, the risk of continuous drought was the highest.
Based on the seasonal precipitation data from 1960 to 2010 in the southwestern Sichuan, combining the percentages of precipitation anomaly, the Copula method is applied to construct the hazard evaluation model of continuous droughts between adjacent seasons for each weather station in the southwestern Sichuan. The results indicate that the Copula function can be applied to construct the hazard evaluation model of continuous droughts between adjacent quarters at each station in the southwestern Sichuan. It is concluded:（1） the hazard degree of spring and summer continuous droughts is the lowest in the southwestern Sichuan, as low as 452% in Leshan.（2） the hazard degree of winter and spring continuous droughts is the highest， high up to 2899% in Panzhihua. （3） by contrast, the hazard degree of spring and summer continuous drought for Panzhihua is the highest, while the lowest in Leshan. For the same kind of continuous droughts, the risks for different stations are different. In general, when there are severe droughts in the adjacent seasons, the risk of continuous droughts is the lowest; when there are light droughts in the adjacent seasons, the risk of continuous drought was the highest.
2015, 43(2):309-313.
Abstract:
Base on the data of daily temperature from 1981 to 2012 and the rolling forecasting of daily temperature in March 2014 at the Haidian meteorological station, the predicting of first flowering date of Prunus discoidea in Beijing Yuyuantan Park is conducted by using the SW Phenological Model. The results show that the errors between the predicted and observed first flowering dates of Prunus discoidea are 3 to 4 days, to predict 10 days ahead of time, and 1 to 2 days, to predict 7 days ahead of time. The deviations of daily temperature prediction are the main cause. The results indicate that the SW model is applicable and well worth popularizing.
Base on the data of daily temperature from 1981 to 2012 and the rolling forecasting of daily temperature in March 2014 at the Haidian meteorological station, the predicting of first flowering date of Prunus discoidea in Beijing Yuyuantan Park is conducted by using the SW Phenological Model. The results show that the errors between the predicted and observed first flowering dates of Prunus discoidea are 3 to 4 days, to predict 10 days ahead of time, and 1 to 2 days, to predict 7 days ahead of time. The deviations of daily temperature prediction are the main cause. The results indicate that the SW model is applicable and well worth popularizing.
2015, 43(2):314-319.
Abstract:
By choosing the data of 7 basic weather stations and the Xi’an sounding station from 1971 to 2013, in combination with the manual observation of haze day records and the standards of visibility (less than 10 km and the relative humidity less than 80%), the temporal and spatial distribution characteristics of haze are analyzed on decadal, seasonal, and monthly scales, as well as the characteristics of wind, rainfall and boundary layer influencing factors when haze appears. The results show: (1) From the 1970s to 2000s, the decadal average number of haze days exhibited a decreaseincreasedecreaseincrease trend in Xi’an. (2) Xian is the main atmospheric pollution area in the Guanzhong area; the number of haze days in Xi’an showed a trend of rise; haze days appeared mainly in winter, and the vulnerable areas remained in the middle East; the influence of urbanization on haze days was significant, more obvious in the urban area and less in the suburbs. (3) The majority of haze weather lasts no more than a week; nearly 95% of haze weather occurred when the wind speed was under 33 m/s; the wind was less than level 1 in more than 50% of haze weather cases. (4) The number of haze days was inversely proportional to the number of rain days, proportional to the number of continuous no rainy days; the low monthly average number of longest continuous no rainy days appeared from April to September, and haze days are few. (5) The special basin topography, the climate trend of yearbyyear decreasing wind speed, and urban industrial pollution in Xi’an are important impact factors for haze weather and its fluctuations.
By choosing the data of 7 basic weather stations and the Xi’an sounding station from 1971 to 2013, in combination with the manual observation of haze day records and the standards of visibility (less than 10 km and the relative humidity less than 80%), the temporal and spatial distribution characteristics of haze are analyzed on decadal, seasonal, and monthly scales, as well as the characteristics of wind, rainfall and boundary layer influencing factors when haze appears. The results show: (1) From the 1970s to 2000s, the decadal average number of haze days exhibited a decreaseincreasedecreaseincrease trend in Xi’an. (2) Xian is the main atmospheric pollution area in the Guanzhong area; the number of haze days in Xi’an showed a trend of rise; haze days appeared mainly in winter, and the vulnerable areas remained in the middle East; the influence of urbanization on haze days was significant, more obvious in the urban area and less in the suburbs. (3) The majority of haze weather lasts no more than a week; nearly 95% of haze weather occurred when the wind speed was under 33 m/s; the wind was less than level 1 in more than 50% of haze weather cases. (4) The number of haze days was inversely proportional to the number of rain days, proportional to the number of continuous no rainy days; the low monthly average number of longest continuous no rainy days appeared from April to September, and haze days are few. (5) The special basin topography, the climate trend of yearbyyear decreasing wind speed, and urban industrial pollution in Xi’an are important impact factors for haze weather and its fluctuations.
2015, 43(2):320-325.
Abstract:
Impact Analysis of Urbanization on Air Temperature of ChongqingOutskirts
Impact Analysis of Urbanization on Air Temperature of ChongqingOutskirts
2015, 43(2):326-330.
Abstract:
Through the investigation of the regularities of lightning disasters for heritage buildings, it is proposed that the assessing indicators of lightning protection for heritage buildings include such factors as the value of heritage buildings, lightning density, the environment, service facilities, heritage building height, surrounding trees, building structure, history, etc. Using the analytic hierarchy process (AHP) to determine the index weight, according to the protection level of heritage buildings and the regularities of lightning disasters and lightning activity, the current national standards, and referring to the Likert scale and the equal weight index to evaluate the indexes, the classification evaluation model of heritage buildings is established. The results are of certain significance to the protection of heritage buildings.
Through the investigation of the regularities of lightning disasters for heritage buildings, it is proposed that the assessing indicators of lightning protection for heritage buildings include such factors as the value of heritage buildings, lightning density, the environment, service facilities, heritage building height, surrounding trees, building structure, history, etc. Using the analytic hierarchy process (AHP) to determine the index weight, according to the protection level of heritage buildings and the regularities of lightning disasters and lightning activity, the current national standards, and referring to the Likert scale and the equal weight index to evaluate the indexes, the classification evaluation model of heritage buildings is established. The results are of certain significance to the protection of heritage buildings.
2015, 43(2):331-337.
Abstract:
The offset position and the expanded width, with which the lightning equivalent area is calculated, are analyzed by establishing the related model and mathematical formula, according to the logical relationship of equivalent area calculation, taking the slopeshaped building and domeshaped building as examples. For the single eaves, the double eaves of ancient buildings or ancient towers, the offset positions should be judged from the relationship of the horizontal distance（〖WTBX〗L〖WTBZ〗）and the vertical distance （〖WTBX〗H〖WTBZ〗） between the eaves and roof (top). For the domeshaped or ellipticalshaped roof buildings，the mathematical formulas from the outside to the central axis are established by using the formula of the roof model. Then the derivatives of the formulas are evaluated. The coordinates with the derivatives being zero (i.e., offset point positions) and the corresponding expanded widths are obtained. The equivalent areas are gained by the means of offsetting and area calculation with AutoCAD software, which provides reference for the accurate calculation of equivalent areas in lightning protection design and disaster risk assessment.
The offset position and the expanded width, with which the lightning equivalent area is calculated, are analyzed by establishing the related model and mathematical formula, according to the logical relationship of equivalent area calculation, taking the slopeshaped building and domeshaped building as examples. For the single eaves, the double eaves of ancient buildings or ancient towers, the offset positions should be judged from the relationship of the horizontal distance（〖WTBX〗L〖WTBZ〗）and the vertical distance （〖WTBX〗H〖WTBZ〗） between the eaves and roof (top). For the domeshaped or ellipticalshaped roof buildings，the mathematical formulas from the outside to the central axis are established by using the formula of the roof model. Then the derivatives of the formulas are evaluated. The coordinates with the derivatives being zero (i.e., offset point positions) and the corresponding expanded widths are obtained. The equivalent areas are gained by the means of offsetting and area calculation with AutoCAD software, which provides reference for the accurate calculation of equivalent areas in lightning protection design and disaster risk assessment.
2015, 43(2):338-342.
Abstract:
Using the experiment data of groundbased artificial rain enhancement in warm clouds carried out in Zhouning Reservoir in Fujian from April 2012 to August 2013， the rain enhancement effectiveness under different conditions is analyzed based on the effectiveness assessment of all cloud seeding experiments with the regional correlation method. The results show that the average enhancement of rainfall in warm clouds in Zhouning Reservoir reaches 51 mm； the effectiveness of rain enhancement is most obvious in warm clouds under the influence of the warm and moist air flowing from southwest； also， the multipoint and multitime rain enhancement operation can help improve the effectiveness. The effectiveness assessment on precipitation enhancement concludes that the precipitation enhancement in warm clouds with grounded stoves is suitable for southern areas.
Using the experiment data of groundbased artificial rain enhancement in warm clouds carried out in Zhouning Reservoir in Fujian from April 2012 to August 2013， the rain enhancement effectiveness under different conditions is analyzed based on the effectiveness assessment of all cloud seeding experiments with the regional correlation method. The results show that the average enhancement of rainfall in warm clouds in Zhouning Reservoir reaches 51 mm； the effectiveness of rain enhancement is most obvious in warm clouds under the influence of the warm and moist air flowing from southwest； also， the multipoint and multitime rain enhancement operation can help improve the effectiveness. The effectiveness assessment on precipitation enhancement concludes that the precipitation enhancement in warm clouds with grounded stoves is suitable for southern areas.
2015, 43(2):343-348.
Abstract:
The temporal and spatial distribution characteristics，the frequency of early warning release, and the accurate rate of meteorological disaster warnings in Guangxi are studied by using the warning notices issued in Guangxi from 2009 to 2012 and the evaluation forms,by means of classification and statistical methods. The results show that such three kinds of disaster weather warnings as heavy rain, lightning, high temperature are most frequently issued. The total number of warnings in the western Guangxi is less than that in the eastern Guangxi. The accuracy rate of the issued warnings is relatively high, and the proportion of advance warnings is the biggest in correct warnings. Considering the new situation faced by early warning, some countermeasures are given to further improve weather forecasting and the level of meteorological warning.
The temporal and spatial distribution characteristics，the frequency of early warning release, and the accurate rate of meteorological disaster warnings in Guangxi are studied by using the warning notices issued in Guangxi from 2009 to 2012 and the evaluation forms,by means of classification and statistical methods. The results show that such three kinds of disaster weather warnings as heavy rain, lightning, high temperature are most frequently issued. The total number of warnings in the western Guangxi is less than that in the eastern Guangxi. The accuracy rate of the issued warnings is relatively high, and the proportion of advance warnings is the biggest in correct warnings. Considering the new situation faced by early warning, some countermeasures are given to further improve weather forecasting and the level of meteorological warning.
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.