Volume 41,Issue 6,2013 Table of Contents
2013, 41(6):977-981.
Abstract:
The frequency synthesizer is an important part of CINRAD, which decides directly the working frequency of the CINRAD transmitter and the coherence of the whole total CINRAD, and is also a key factor influencing the phase noise in CINRAD. At present, radar users usually think it as a black box: only know its output signal parameters without locating the inter faults. The working principles and the block diagram of integrated generator of CINRAD/SB are explained, based on which, some examples of its fault location are given by making use of the standardized maintenance process of electronic equipment, combined with the radar fault phenomena. The procedures of fault location for radar users are illustrated，so to help radar maintenance personnel improve the capability of equipment technical support.
The frequency synthesizer is an important part of CINRAD, which decides directly the working frequency of the CINRAD transmitter and the coherence of the whole total CINRAD, and is also a key factor influencing the phase noise in CINRAD. At present, radar users usually think it as a black box: only know its output signal parameters without locating the inter faults. The working principles and the block diagram of integrated generator of CINRAD/SB are explained, based on which, some examples of its fault location are given by making use of the standardized maintenance process of electronic equipment, combined with the radar fault phenomena. The procedures of fault location for radar users are illustrated，so to help radar maintenance personnel improve the capability of equipment technical support.
2013, 41(6):982-987.
Abstract:
Failure analysis and diagnostic techniques are important in the protection of large scale meteorological equipment and the reliable operation. According to the signal flow of CINRAD/SB antenna feeder system, through studying the fault diagnosis methods of the CINRAD antenna feeder system, the detection methods of antenna feeder system leakage and lighting faults, the fault diagnosis process of big antenna feeder systems loss, and six methods of fault location are summed up. According to the process of fault diagnosis and the spectrum analyzer method with external signal sources, the diagnosis and analysis are made of the typical example of weak radar echo intensity and reduced sensitivity resulted from circulation failure within the antenna pedestal. The results indicate that considering the instrument status at the radar site, through the process of fault diagnosis, the use of appropriate methods and techniques can achieve the quick location of antenna feeder system faults, so to repair radar failure timely.
Failure analysis and diagnostic techniques are important in the protection of large scale meteorological equipment and the reliable operation. According to the signal flow of CINRAD/SB antenna feeder system, through studying the fault diagnosis methods of the CINRAD antenna feeder system, the detection methods of antenna feeder system leakage and lighting faults, the fault diagnosis process of big antenna feeder systems loss, and six methods of fault location are summed up. According to the process of fault diagnosis and the spectrum analyzer method with external signal sources, the diagnosis and analysis are made of the typical example of weak radar echo intensity and reduced sensitivity resulted from circulation failure within the antenna pedestal. The results indicate that considering the instrument status at the radar site, through the process of fault diagnosis, the use of appropriate methods and techniques can achieve the quick location of antenna feeder system faults, so to repair radar failure timely.
3 Analysis of Bias Between Geopotential and Geometric Heights for GFE(L)1 Secondary Wind Finding Radar
2013, 41(6):988-992.
Abstract:
In the process of GFE(L)1 Secondary Wind finding Radar sounding, the difference between geopotential and geometric heights shown on the monitoring interface can be large, sometimes up to 4000 m or 5000 m, far beyond the normal range, thus causing problems for observers in record analysis. Various sources of the bias and possible reasons are discussed, and the possible error ranges are estimated and categorized. Some practical suggestions are given about bias correction approaches.
In the process of GFE(L)1 Secondary Wind finding Radar sounding, the difference between geopotential and geometric heights shown on the monitoring interface can be large, sometimes up to 4000 m or 5000 m, far beyond the normal range, thus causing problems for observers in record analysis. Various sources of the bias and possible reasons are discussed, and the possible error ranges are estimated and categorized. Some practical suggestions are given about bias correction approaches.
2013, 41(6):993-997.
Abstract:
The real time monitoring of radar products is an important part of real time running and monitoring services in the CMA Meteorological Observation Centre, and the automated identification of abnormal radar products will therefore have practical significance and research value. The identification system based on image processing technology to achieve the automatic recognition of abnormal radar products is discussed, and the system model and automatic recognition algorithm of radar data abnormity are introduced in detail, aiming at the feature extraction, iterative learning, and so on. The analysis of the detected radar product abnormalities shows that the automatic identification system based on image processing technology can detect abnormal radar products efficiently in real time to facilitate the quick location of abnormal radar and timely repair, and can also be used as a basis for radar repair or for radar upgrading to improve the efficiency of radar applications.
The real time monitoring of radar products is an important part of real time running and monitoring services in the CMA Meteorological Observation Centre, and the automated identification of abnormal radar products will therefore have practical significance and research value. The identification system based on image processing technology to achieve the automatic recognition of abnormal radar products is discussed, and the system model and automatic recognition algorithm of radar data abnormity are introduced in detail, aiming at the feature extraction, iterative learning, and so on. The analysis of the detected radar product abnormalities shows that the automatic identification system based on image processing technology can detect abnormal radar products efficiently in real time to facilitate the quick location of abnormal radar and timely repair, and can also be used as a basis for radar repair or for radar upgrading to improve the efficiency of radar applications.
2013, 41(6):998-1002.
Abstract:
At present, the test and maintenance of weather radar mainly rely on traditional desktop instruments. Its limited functions and poor mobility restrict the diagnoses and repair of radar malfunctions, and induce a baneful influence to meteorological service. The principles and function parameters of radar receivers are analyzed. The hardware framework and software characteristics of the virtual instruments are introduced. Taking the IF band width testing as an example, the design ideas, work principles, and operating methods of the virtual instruments system are discussed. With the advantages of using portable modularized PXI instruments as hardware and software programing as its kernel, having overcome the disadvantages of traditional ones and having good environmental adaptability and capability of function expansion, this system is especially suitable for the site tests in radar stations.
At present, the test and maintenance of weather radar mainly rely on traditional desktop instruments. Its limited functions and poor mobility restrict the diagnoses and repair of radar malfunctions, and induce a baneful influence to meteorological service. The principles and function parameters of radar receivers are analyzed. The hardware framework and software characteristics of the virtual instruments are introduced. Taking the IF band width testing as an example, the design ideas, work principles, and operating methods of the virtual instruments system are discussed. With the advantages of using portable modularized PXI instruments as hardware and software programing as its kernel, having overcome the disadvantages of traditional ones and having good environmental adaptability and capability of function expansion, this system is especially suitable for the site tests in radar stations.
2013, 41(6):1003-1007.
Abstract:
Based on the forward scatter visibility instrument working principle, the structural characteristics, operating environment, measurement error, causes for errors, and the error model of the forward scatter visibility instrument are analyzed. The factory calibration method, calibration parameters, and calibration parameters correction methods of the forward scatter visibility instrument are summed up, according to the needs of dissemination in the future, so to ensure the accuracy of visibility observation data. Based on the transmit parameter analysis of visibility values, the laboratory calibration method and calibration conditions of the forward scatter visibility instrument are put forwarded. The field optical device calibration, calibration plate, and manual calibration methods are discussed, to provide the references for the development of the future dissemination system and the establishment of the related calibration standards.
Based on the forward scatter visibility instrument working principle, the structural characteristics, operating environment, measurement error, causes for errors, and the error model of the forward scatter visibility instrument are analyzed. The factory calibration method, calibration parameters, and calibration parameters correction methods of the forward scatter visibility instrument are summed up, according to the needs of dissemination in the future, so to ensure the accuracy of visibility observation data. Based on the transmit parameter analysis of visibility values, the laboratory calibration method and calibration conditions of the forward scatter visibility instrument are put forwarded. The field optical device calibration, calibration plate, and manual calibration methods are discussed, to provide the references for the development of the future dissemination system and the establishment of the related calibration standards.
2013, 41(6):1008-1012.
Abstract:
To grasp the observability of weighing gauges for liquid precipitation and promote the automation of precipitation observation, a statistics analysis is carried out on the precipitation processes occurred in the spring and summer of 2011, and a comparison is conducted between DSH1 and SL3 1 sensors at Beijing Weather Observatory on the characteristics of precipitation dada. The results show that the data obtained from DSH1 are basically as reliable as SL3 1，and the differences of data between the two sensors are negligible during light rain processes, but cannot be neglected during moderate and heavy rain processes. Since failures of DSH1 were found out during use, the reliability of the instrument still needs to be improved.
To grasp the observability of weighing gauges for liquid precipitation and promote the automation of precipitation observation, a statistics analysis is carried out on the precipitation processes occurred in the spring and summer of 2011, and a comparison is conducted between DSH1 and SL3 1 sensors at Beijing Weather Observatory on the characteristics of precipitation dada. The results show that the data obtained from DSH1 are basically as reliable as SL3 1，and the differences of data between the two sensors are negligible during light rain processes, but cannot be neglected during moderate and heavy rain processes. Since failures of DSH1 were found out during use, the reliability of the instrument still needs to be improved.
2013, 41(6):1013-1016.
Abstract:
The electrical equipments in automatic weather stations are often stricken and damaged by lightning strokes inducted from AC power lines, and various currently installed lightning arresters cannot effectively prevent the occurrence of the like events. A newly designed and developed lightning protection power switch is introduced, which can isolate electronic equipment from alternating current, uses two groups of storage batteries alternately to supply electric power. The switch detects the battery’s supplying voltage and controls the rotation direction of two micro motors. Through the motors’ transmission devices, the contact point can be shifted. Consequently the two groups of storage batteries can alternately supply power and be recharged. By adjusting the motor’s stroke, the distance between charger and equipment can be 8 cm to 10 cm, and the isolation between power and equipment devices is archived. The lightning inducted accidents and damages through AC power lines can be prevented.
The electrical equipments in automatic weather stations are often stricken and damaged by lightning strokes inducted from AC power lines, and various currently installed lightning arresters cannot effectively prevent the occurrence of the like events. A newly designed and developed lightning protection power switch is introduced, which can isolate electronic equipment from alternating current, uses two groups of storage batteries alternately to supply electric power. The switch detects the battery’s supplying voltage and controls the rotation direction of two micro motors. Through the motors’ transmission devices, the contact point can be shifted. Consequently the two groups of storage batteries can alternately supply power and be recharged. By adjusting the motor’s stroke, the distance between charger and equipment can be 8 cm to 10 cm, and the isolation between power and equipment devices is archived. The lightning inducted accidents and damages through AC power lines can be prevented.
2013, 41(6):1017-1020.
Abstract:
The publications of international Surge Protection Device (SPD) standards issued by the International Electro technical Commission (IEC) are introduced. Through comparing the latest standards of the low voltage surge protection device test (IEC61643 11: 2011) with the 2005 and 1998 versions, the modifications in the new standard are demonstrated in aspects of the category, applicability, electrical performance requirements, and test methods, focused on the analysis of important content and reasons for change in the new standards, aiming to help SPD manufacturers, testing organizations, and users to understand these modifications quickly. It is pointed out that the CQC authentication should be adopted according to the international practices in the SPD standards and the SPD market, to strengthen the regulation of the market.
The publications of international Surge Protection Device (SPD) standards issued by the International Electro technical Commission (IEC) are introduced. Through comparing the latest standards of the low voltage surge protection device test (IEC61643 11: 2011) with the 2005 and 1998 versions, the modifications in the new standard are demonstrated in aspects of the category, applicability, electrical performance requirements, and test methods, focused on the analysis of important content and reasons for change in the new standards, aiming to help SPD manufacturers, testing organizations, and users to understand these modifications quickly. It is pointed out that the CQC authentication should be adopted according to the international practices in the SPD standards and the SPD market, to strengthen the regulation of the market.
2013, 41(6):1021-1025.
Abstract:
The European Center for Medium Range Weather Forecasts (ECMWF) has begun to offer high resolution products since January 2010, which affects the integrity of TIGGE data receiving in the China Meteorological Administration, causing significant data loss. The various factors affecting data receiving are analyzed, respectively. It is found that using the TCP transport protocol for data sharing has a bottleneck in application in the present network environment of high bandwidth and high time delay, which therefore restrains the network throughout and cannot satisfy huge data transmission requirements. The performance of TCP protocol and the throughput of current network are improved by adjusting the size of the TCP receiving window of the TIGGE system. Through adjusting, the situation of data receiving in the China Meteorological Administration is consistent with other global centers, realizing the integrity of data receiving of all global centers.
The European Center for Medium Range Weather Forecasts (ECMWF) has begun to offer high resolution products since January 2010, which affects the integrity of TIGGE data receiving in the China Meteorological Administration, causing significant data loss. The various factors affecting data receiving are analyzed, respectively. It is found that using the TCP transport protocol for data sharing has a bottleneck in application in the present network environment of high bandwidth and high time delay, which therefore restrains the network throughout and cannot satisfy huge data transmission requirements. The performance of TCP protocol and the throughput of current network are improved by adjusting the size of the TCP receiving window of the TIGGE system. Through adjusting, the situation of data receiving in the China Meteorological Administration is consistent with other global centers, realizing the integrity of data receiving of all global centers.
2013, 41(6):1026-1030.
Abstract:
Based on the Redundant Array of Inexpensive Disks (RAID), and Logical Volume Management (LVM) tools, a rack mount server and five connected disk arrays are combined into a single logical disk with massive storage space of up to 90 TB. This program focuses on the stability of the system and the data security on the disk array series, increases the scalability, and theoretically can expand indefinitely. Practical application shows that this program facilitates the security and fast access of the data used operationally in numerical weather prediction, and has a capacity of scalability, so to meet the scientific data storage requirements of meteorological departments at the provincial level, especially the needs of numerical prediction verification for mass storage.
Based on the Redundant Array of Inexpensive Disks (RAID), and Logical Volume Management (LVM) tools, a rack mount server and five connected disk arrays are combined into a single logical disk with massive storage space of up to 90 TB. This program focuses on the stability of the system and the data security on the disk array series, increases the scalability, and theoretically can expand indefinitely. Practical application shows that this program facilitates the security and fast access of the data used operationally in numerical weather prediction, and has a capacity of scalability, so to meet the scientific data storage requirements of meteorological departments at the provincial level, especially the needs of numerical prediction verification for mass storage.
2013, 41(6):1031-1035.
Abstract:
Considering the method of taking tapes out of the STK9310 tape library is purely manual, error prone, and inefficient, the commands of searching the database provided by the Legato NetWorker software and the commands of searching the tapes provided by ACSLS are thoroughly studied, and the networker architecture is analyzed in detail, based on the premise that Legato NetWorker server and ACSLS server are accessible to each other remotely without a password. A shell script is designed in the HP UX environment to realize the automatic retrieval of tapes that had been full of data and to identify whether the data are in the tape library or not, thus to decide which tapes should be taken out of the tape library and produce a tape list incidentally.
Considering the method of taking tapes out of the STK9310 tape library is purely manual, error prone, and inefficient, the commands of searching the database provided by the Legato NetWorker software and the commands of searching the tapes provided by ACSLS are thoroughly studied, and the networker architecture is analyzed in detail, based on the premise that Legato NetWorker server and ACSLS server are accessible to each other remotely without a password. A shell script is designed in the HP UX environment to realize the automatic retrieval of tapes that had been full of data and to identify whether the data are in the tape library or not, thus to decide which tapes should be taken out of the tape library and produce a tape list incidentally.
2013, 41(6):1036-1042.
Abstract:
A distributed meteorological content management system is proposed, which is built based on the Chinese meteorological system, including the central and provincial meteorological information network and servers. Methods, such as LDM communication transmission, storage/content management, graphical product generation system, ontological meteorological services, and multi scale objective analysis, are applied as components to build up a distributed meteorological content management system covering the central and provincial meteorological operations and services. Experiments shows that the proposed content management system, in which the unified definition of interfaces and expressions are adopted, can effectively improve the meteorological data accessing, sharing, and processing efficiency, and accelerate the development of a variety of meteorological services, broaden the meteorological information service range.
A distributed meteorological content management system is proposed, which is built based on the Chinese meteorological system, including the central and provincial meteorological information network and servers. Methods, such as LDM communication transmission, storage/content management, graphical product generation system, ontological meteorological services, and multi scale objective analysis, are applied as components to build up a distributed meteorological content management system covering the central and provincial meteorological operations and services. Experiments shows that the proposed content management system, in which the unified definition of interfaces and expressions are adopted, can effectively improve the meteorological data accessing, sharing, and processing efficiency, and accelerate the development of a variety of meteorological services, broaden the meteorological information service range.
2013, 41(6):1043-1048.
Abstract:
The Meteorological Disasters Sharing System (MDSS) is designed to collect, report, transfer, process, apply, and manage the data of both real time and historical meteorological disasters. The system is divided into three layers: collect transmission, data logic, and application service. It consists of five components: disaster reporting client, data transmission subsystem, disaster pre processing and storage subsystem, meteorological disaster data sharing website, and comprehensive meteorological disaster database. The relevant key technologies, including the collection standards, quality control, and spatial analysis of disaster data, are discussed. The operational applications in national meteorological departments show that the system has achieved the collection, processing, analysis and sharing of meteorological disaster data (drought, torrential rains, typhoons, high temperature, low temperature, etc.) to meet the demands of severe weather forecasting and services. It will also play an important role in guiding meteorological departments at all levels to build a meteorological disasters sharing system.
The Meteorological Disasters Sharing System (MDSS) is designed to collect, report, transfer, process, apply, and manage the data of both real time and historical meteorological disasters. The system is divided into three layers: collect transmission, data logic, and application service. It consists of five components: disaster reporting client, data transmission subsystem, disaster pre processing and storage subsystem, meteorological disaster data sharing website, and comprehensive meteorological disaster database. The relevant key technologies, including the collection standards, quality control, and spatial analysis of disaster data, are discussed. The operational applications in national meteorological departments show that the system has achieved the collection, processing, analysis and sharing of meteorological disaster data (drought, torrential rains, typhoons, high temperature, low temperature, etc.) to meet the demands of severe weather forecasting and services. It will also play an important role in guiding meteorological departments at all levels to build a meteorological disasters sharing system.
2013, 41(6):1049-1052.
Abstract:
Based on the requirements for basic meteorological information transmission of the reformed ground based observation, according to the modular design principles, using FTP remote query, remote database query, telephone dialing, SMS sending, and a variety of other programming techniques, an operational meteorological information transmitting and monitoring system for basic stations was developed, which made it possible to monitor the uplink meteorological information in real time. The operational application indicates that the system performed satisfactorily and stably, which help improve the efficiency and quality of meteorological service.
Based on the requirements for basic meteorological information transmission of the reformed ground based observation, according to the modular design principles, using FTP remote query, remote database query, telephone dialing, SMS sending, and a variety of other programming techniques, an operational meteorological information transmitting and monitoring system for basic stations was developed, which made it possible to monitor the uplink meteorological information in real time. The operational application indicates that the system performed satisfactorily and stably, which help improve the efficiency and quality of meteorological service.
2013, 41(6):1053-1056.
Abstract:
The analysis and application system of regional meteorological observation data developed by the Pu’er municipal meteorological service are introduced. The software was constructed as a Client/Server framework, using the Microsoft SQL_server Database to store observation data. Based on the integrated technologies of Microsoft Visual Basic and Mapinfo Mapx activeX, an application platform was constructed. The integrated functional modules are able to display, inquire, analyze, and process various meteorological data, such as contour line drawing for meteorological elements, weather radar echo displaying, and audible or animated graphic alarming. The major functions and working principles of the system are introduced, and its application effects in meteorological services are described.
The analysis and application system of regional meteorological observation data developed by the Pu’er municipal meteorological service are introduced. The software was constructed as a Client/Server framework, using the Microsoft SQL_server Database to store observation data. Based on the integrated technologies of Microsoft Visual Basic and Mapinfo Mapx activeX, an application platform was constructed. The integrated functional modules are able to display, inquire, analyze, and process various meteorological data, such as contour line drawing for meteorological elements, weather radar echo displaying, and audible or animated graphic alarming. The major functions and working principles of the system are introduced, and its application effects in meteorological services are described.
2013, 41(6):1057-1060.
Abstract:
The system architecture of SMS (Supervisor Monitor Scheduler) is described，and the characteristics of GRAPES (Global and Regional Assimilation and Prediction System) numerical prediction are analyzed, and the conventional and the SMS based GRAPES operating technology and running processes are compared. This SMS base system builds a GRAPES numerical prediction automation system with the client/server architecture, divides the running process of GRAPES numerical prediction models reasonably, combines the similar functions of GRAPES modules, splits a complex single module into multiple tasks, simplifies the function of the individual tasks, and displays the processes of the models using the intuitive graphical interface in the implementation process by means of SMS technology. The system has achieved the automation of GRAPES numerical prediction operation, improved greatly the operating capability of GRAPES models, can ensure the reliability and timeliness of GRAPES models.
The system architecture of SMS (Supervisor Monitor Scheduler) is described，and the characteristics of GRAPES (Global and Regional Assimilation and Prediction System) numerical prediction are analyzed, and the conventional and the SMS based GRAPES operating technology and running processes are compared. This SMS base system builds a GRAPES numerical prediction automation system with the client/server architecture, divides the running process of GRAPES numerical prediction models reasonably, combines the similar functions of GRAPES modules, splits a complex single module into multiple tasks, simplifies the function of the individual tasks, and displays the processes of the models using the intuitive graphical interface in the implementation process by means of SMS technology. The system has achieved the automation of GRAPES numerical prediction operation, improved greatly the operating capability of GRAPES models, can ensure the reliability and timeliness of GRAPES models.
2013, 41(6):1061-1067.
Abstract:
Based on the conventional data, GFS reanalysisi data, and satellite images of FY 2C, two MCC processes in 2007 are analyzed, with emphasis on the environmental flow and synoptic physical conditions. The results demonstrate: several mseo β and meso α scale cloud clusters intensified and merged, from which the MCCs formed; the MCCs developed in the favorable environmental field, with the trough in the middle layer, the warm cold shear and the broad warm wet airflow in the lower layer. The enhancement of the southwestward warm wet airflow and the formation and maintenance of the warm shear line in the lower layer were the key factors to MCC formation; the joint influencing of cold air and moist warm flow led to energy frontogenesis. The coupling of frontogenesis in lower layer and its associated strong divergence in the right rear of the high level jet were the main dynamical mechanisms of MCC formation. There existed anticyclone divergence flow in the upper layer, and cyclone convergence flow in the middle lower layer, and the vertical vorticity column supplied favorable dynamical mechanism in the rainstorm centre.
Based on the conventional data, GFS reanalysisi data, and satellite images of FY 2C, two MCC processes in 2007 are analyzed, with emphasis on the environmental flow and synoptic physical conditions. The results demonstrate: several mseo β and meso α scale cloud clusters intensified and merged, from which the MCCs formed; the MCCs developed in the favorable environmental field, with the trough in the middle layer, the warm cold shear and the broad warm wet airflow in the lower layer. The enhancement of the southwestward warm wet airflow and the formation and maintenance of the warm shear line in the lower layer were the key factors to MCC formation; the joint influencing of cold air and moist warm flow led to energy frontogenesis. The coupling of frontogenesis in lower layer and its associated strong divergence in the right rear of the high level jet were the main dynamical mechanisms of MCC formation. There existed anticyclone divergence flow in the upper layer, and cyclone convergence flow in the middle lower layer, and the vertical vorticity column supplied favorable dynamical mechanism in the rainstorm centre.
2013, 41(6):1068-1072.
Abstract:
Based on the observation data of ground and snow surface temperature from five weather stations at Changji from 2008 to 2010, the 0 cm maximum and minimum ground and snow surface temperature, cloudiness, sunshine duration, and snow depth dada are analyzed. The relation between snow surface and ground temperature at different snow depths is studied, and the relation model is verified with the snow depth data in 2011 from Tianchi Station. The results indicate that there are three snow depth demarcations in the relation of ground and snow surface temperature: 5 cm, 6 to 40cm, and greater than 40 cm. When the accumulated snow depth is between 0 to 5 cm, the ground temperature differs from snow temperature, obviously influenced by snow depth and weather conditions; when the snow depth is between 6 to 40 cm, the ground temperature is mainly influenced by snow depth; when snow depth is greater than 40 cm, the ground temperature tends to be unchanged.
Based on the observation data of ground and snow surface temperature from five weather stations at Changji from 2008 to 2010, the 0 cm maximum and minimum ground and snow surface temperature, cloudiness, sunshine duration, and snow depth dada are analyzed. The relation between snow surface and ground temperature at different snow depths is studied, and the relation model is verified with the snow depth data in 2011 from Tianchi Station. The results indicate that there are three snow depth demarcations in the relation of ground and snow surface temperature: 5 cm, 6 to 40cm, and greater than 40 cm. When the accumulated snow depth is between 0 to 5 cm, the ground temperature differs from snow temperature, obviously influenced by snow depth and weather conditions; when the snow depth is between 6 to 40 cm, the ground temperature is mainly influenced by snow depth; when snow depth is greater than 40 cm, the ground temperature tends to be unchanged.
2013, 41(6):1073-1079.
Abstract:
Based on the climate data of sunshine duration, precipitation, average temperature, and so on from 15 representative meteorological stations in Yunnan Province from 1961 to 2010, the natural dry wet climate change and its regional differences in different seasons are analyzed. The results show that the relative moisture index can quantitatively and accurately express the natural climate wet dry status, and objectively reflect the variation over the years and the regional differences for dry wet climate in Yunnan. In the respect of variation trends, potential evapotranspiration was increasing and precipitation was decreasing during both dry and wet seasons since the mid 1990s, which led to obvious aridification trend jointly in Yunnan under the background of climate warming. Meanwhile, the relative moisture index of Yunnan had the bigger inter annual fluctuations in dry season (compared to rainy season) and obvious inter decadal differences. The wet dry climate status of rainy season showed evident periodic variation trends in all regions. Flood drought climate changes of five regions in Yunnan had both consistencies and differences. Especially, the central Yunnan was obviously consistent with the southwestern part, while the northwest was distinctly different from the southeast. The northeast had distinction during rainy season but claimed similarity in dry season with northwest Yunnan.
Based on the climate data of sunshine duration, precipitation, average temperature, and so on from 15 representative meteorological stations in Yunnan Province from 1961 to 2010, the natural dry wet climate change and its regional differences in different seasons are analyzed. The results show that the relative moisture index can quantitatively and accurately express the natural climate wet dry status, and objectively reflect the variation over the years and the regional differences for dry wet climate in Yunnan. In the respect of variation trends, potential evapotranspiration was increasing and precipitation was decreasing during both dry and wet seasons since the mid 1990s, which led to obvious aridification trend jointly in Yunnan under the background of climate warming. Meanwhile, the relative moisture index of Yunnan had the bigger inter annual fluctuations in dry season (compared to rainy season) and obvious inter decadal differences. The wet dry climate status of rainy season showed evident periodic variation trends in all regions. Flood drought climate changes of five regions in Yunnan had both consistencies and differences. Especially, the central Yunnan was obviously consistent with the southwestern part, while the northwest was distinctly different from the southeast. The northeast had distinction during rainy season but claimed similarity in dry season with northwest Yunnan.
2013, 41(6):1080-1085.
Abstract:
Affected by the mountain underlying surface, temperature distribution sometimes appears anomalies, i.e., terrain inversion (the temperature on the mountain top is greater than that at the foot of the mountain) in the Jiuhua Mountain during the period of temperature increase. Through the comparison of temperatures at different heights in the mountains and the diurnal variation characteristics of analysis， it is concluded that： terrain inversion usually appears in the temperature increase period in the mountains, and the anomalous characteristics in the vertical distribution of daily minimum temperature are most obvious (compared with daily average temperature and maximum temperature)； the terrain inversion of minimum temperature has obvious seasonal characteristics；the terrain inversion of the daily minimum temperature has good indicative significance to weather changes. After the disappearing of terrain inversion in the warming period, there will certainly is a cooling, in which rainfall and complex weather situation will happen. There is a fairly good relationship between the time and amplitude of terrain inversion and the subsequent cooling duration and cooling amplitude. Therefore, to analyze the spatial and temporal variation of temperature in the complicated mountainous terrain is helpful for temperature prediction.
Affected by the mountain underlying surface, temperature distribution sometimes appears anomalies, i.e., terrain inversion (the temperature on the mountain top is greater than that at the foot of the mountain) in the Jiuhua Mountain during the period of temperature increase. Through the comparison of temperatures at different heights in the mountains and the diurnal variation characteristics of analysis， it is concluded that： terrain inversion usually appears in the temperature increase period in the mountains, and the anomalous characteristics in the vertical distribution of daily minimum temperature are most obvious (compared with daily average temperature and maximum temperature)； the terrain inversion of minimum temperature has obvious seasonal characteristics；the terrain inversion of the daily minimum temperature has good indicative significance to weather changes. After the disappearing of terrain inversion in the warming period, there will certainly is a cooling, in which rainfall and complex weather situation will happen. There is a fairly good relationship between the time and amplitude of terrain inversion and the subsequent cooling duration and cooling amplitude. Therefore, to analyze the spatial and temporal variation of temperature in the complicated mountainous terrain is helpful for temperature prediction.
2013, 41(6):1086-1090.
Abstract:
The statistical results from the rain gauge data extracted every 5 minutes are used to analyze the temporal spatial distribution variations of short period heavy precipitation in Dujiangyan. The results show: (1) the maximum of hourly rainfall occurs usually in high altitude areas. The maximum hourly rainfall has a big weight in total precipitation in the same event, which reflects that the rainfall in Dujiangyan is characterized by high intensity and concentrative precipitation time. (2) Influenced by the effect of landform and the radiative cooling of cloud tops, short period heavy precipitation in Dujiangyan primarily occurs at night, and there occur more freguently rains after midnight than before midnight. (3) Heavy precipitation occurs first along the windward slope of the mountains in summer, and afterwards，convection systems move towards southeast areas. (4) The durations of short period heavy precipitation in Dujiangyan are calculated. The precipitation duration ranges from 60 to 130 minutes generally, with the maximum up to 210 minutes.
The statistical results from the rain gauge data extracted every 5 minutes are used to analyze the temporal spatial distribution variations of short period heavy precipitation in Dujiangyan. The results show: (1) the maximum of hourly rainfall occurs usually in high altitude areas. The maximum hourly rainfall has a big weight in total precipitation in the same event, which reflects that the rainfall in Dujiangyan is characterized by high intensity and concentrative precipitation time. (2) Influenced by the effect of landform and the radiative cooling of cloud tops, short period heavy precipitation in Dujiangyan primarily occurs at night, and there occur more freguently rains after midnight than before midnight. (3) Heavy precipitation occurs first along the windward slope of the mountains in summer, and afterwards，convection systems move towards southeast areas. (4) The durations of short period heavy precipitation in Dujiangyan are calculated. The precipitation duration ranges from 60 to 130 minutes generally, with the maximum up to 210 minutes.
2013, 41(6):1091-1094.
Abstract:
It is important content of meteorological science and technology service to evaluate the return periods of climate extremes scientifically and reasonably, and it is of great significance to local economic development. For 35 kinds of climate extremes in Heze, by means of the Pearson Ⅲ, log normal, Gumbel, and Weibull distributions, the fittings of the climate extremes are conducted respectively. The optimal distribution functions are selected through χ2 test, and the climatic extremes of return periods are calculated through several return periods. Through the selection of the optimal distribution functions, the certain types of climate element subordinates to certain distribution function are studied. The results show that the extremes of the number of days and extreme temperatures are more likely obedient to the Pearson Ⅲ distribution, while precipitation and other extremes are more likely obedient to the Gumbel distribution. Some tips for using Excel calculation are introduced briefly.
It is important content of meteorological science and technology service to evaluate the return periods of climate extremes scientifically and reasonably, and it is of great significance to local economic development. For 35 kinds of climate extremes in Heze, by means of the Pearson Ⅲ, log normal, Gumbel, and Weibull distributions, the fittings of the climate extremes are conducted respectively. The optimal distribution functions are selected through χ2 test, and the climatic extremes of return periods are calculated through several return periods. Through the selection of the optimal distribution functions, the certain types of climate element subordinates to certain distribution function are studied. The results show that the extremes of the number of days and extreme temperatures are more likely obedient to the Pearson Ⅲ distribution, while precipitation and other extremes are more likely obedient to the Gumbel distribution. Some tips for using Excel calculation are introduced briefly.
2013, 41(6):1095-1100.
Abstract:
Using radiosonde and FY 2E Satellite data, a quantitative analysis of satellite cloud images and physical fields is conducted on two rainstorm processes induced by the subtropical high and westerly trough in August 2005 and August 2010. It is found that there was a continuous complete cloud band at the east of the trough line at 500 hPa and near the boundary of the cold air side, the cloud band was smooth and neat. The cloud system was a typical frontal cloud system, and from a structural point of view, the frontal cloud band was mainly composed by the multi layer cloud systems. The entire cloud band was located between line 580 and line 588, which was composed of convective clouds, a stable precipitation cloud band and mixed precipitation cloud band. The convective clouds were concentrated near the clear zone at the edge of the subtropical high, usually located close to the subtropical high between line 584 and line 588. The stable precipitation was concentrated on the back of the cloud band between line 580 and line 584; the mixed precipitation occurred in the vicinity of the line 584 between two cloud systems. The distribution of the cloud system had a very good correspondence with the vertical velocity field, vorticity field, divergence field, and high level vorticity advection field. The distribution characteristics of temperature and humidity parameters, such as humidity flux, humidity flux divergence, and pseudo equivalent potential temperature, gave a clear explanation of the movement, development, and distribution characteristics of the frontal cloud bands.
Using radiosonde and FY 2E Satellite data, a quantitative analysis of satellite cloud images and physical fields is conducted on two rainstorm processes induced by the subtropical high and westerly trough in August 2005 and August 2010. It is found that there was a continuous complete cloud band at the east of the trough line at 500 hPa and near the boundary of the cold air side, the cloud band was smooth and neat. The cloud system was a typical frontal cloud system, and from a structural point of view, the frontal cloud band was mainly composed by the multi layer cloud systems. The entire cloud band was located between line 580 and line 588, which was composed of convective clouds, a stable precipitation cloud band and mixed precipitation cloud band. The convective clouds were concentrated near the clear zone at the edge of the subtropical high, usually located close to the subtropical high between line 584 and line 588. The stable precipitation was concentrated on the back of the cloud band between line 580 and line 584; the mixed precipitation occurred in the vicinity of the line 584 between two cloud systems. The distribution of the cloud system had a very good correspondence with the vertical velocity field, vorticity field, divergence field, and high level vorticity advection field. The distribution characteristics of temperature and humidity parameters, such as humidity flux, humidity flux divergence, and pseudo equivalent potential temperature, gave a clear explanation of the movement, development, and distribution characteristics of the frontal cloud bands.
2013, 41(6):1101-1108.
Abstract:
The characteristics of Radar echoes during the heavy rainfall event from 9 to 16 July 2010 along the Yangtze River in Anhui are analyzed on the basis of conventional meteorological data and Doppler radar data of Hefe Station. It is concluded that the favorable larger scale circulation，ample water vapor, and stronger ascending movement are the advantageous weather background for the severe rainfall. The results show that the source regions of heavy rainfall along the Yangze River in Anhui are often in the Dabie Mountains. The formation and development of radar echoes during heavy rains are always related with the local strong convergence in wind field (adverse wind regions). Heavy rainfall events are prone to happen when rainbelts are combined along the low level shear line and then strengthened, and when single echoes move in the same direction with the larger scale rainbelt area slowly or quasi stationarily.
The characteristics of Radar echoes during the heavy rainfall event from 9 to 16 July 2010 along the Yangtze River in Anhui are analyzed on the basis of conventional meteorological data and Doppler radar data of Hefe Station. It is concluded that the favorable larger scale circulation，ample water vapor, and stronger ascending movement are the advantageous weather background for the severe rainfall. The results show that the source regions of heavy rainfall along the Yangze River in Anhui are often in the Dabie Mountains. The formation and development of radar echoes during heavy rains are always related with the local strong convergence in wind field (adverse wind regions). Heavy rainfall events are prone to happen when rainbelts are combined along the low level shear line and then strengthened, and when single echoes move in the same direction with the larger scale rainbelt area slowly or quasi stationarily.
2013, 41(6):1109-1115.
Abstract:
An analysis is made of the causes of strong wind weather in Zhejiang during the typhoon Morakot by using the conventional radiosonde, automatic station, NCEP/NCAR 1°×1° reanalysis, and Doppler radar data. Results show that strong winds had the characteristics of early influence, long duration, wide scope, and strong intensity. The strengthened and westward moved subtropical high is the main cause that made the strong wind appear earlier. The typhoon moved slowly, which was caused by the saddle field and the interaction of three typhoons, leading to the persisting strong wind. The maintenance of pressure gradient is the cause of earlier and wider strong wind influence. The analysis indicates that the downward transport of high level momentum and the downward moving wind speed center enhanced the surface winds. The velocity products of Doppler radar can also be used as important references for forecasting extreme wind speeds in typhoons.
An analysis is made of the causes of strong wind weather in Zhejiang during the typhoon Morakot by using the conventional radiosonde, automatic station, NCEP/NCAR 1°×1° reanalysis, and Doppler radar data. Results show that strong winds had the characteristics of early influence, long duration, wide scope, and strong intensity. The strengthened and westward moved subtropical high is the main cause that made the strong wind appear earlier. The typhoon moved slowly, which was caused by the saddle field and the interaction of three typhoons, leading to the persisting strong wind. The maintenance of pressure gradient is the cause of earlier and wider strong wind influence. The analysis indicates that the downward transport of high level momentum and the downward moving wind speed center enhanced the surface winds. The velocity products of Doppler radar can also be used as important references for forecasting extreme wind speeds in typhoons.
2013, 41(6):1116-1121.
Abstract:
The NCEP/NCAR reanalysis data (1°×1°，6 h) in January 2011 and the observation data in winter from 1970 to 2011 provided by Guizhou Meteorological Service are used to investigate the climatic characteristics of freezing disaster occurred in January 2011 and its causes by climate statistics and climate diagnostic methods. More than 34 stations reached the lowest temperature in the past 40 years during the freezing rain event. There were active blocking anticyclones near the Ural Mountains persistently, which were more active than the normal. They were broken down twice and rebuilt thrice, with the wet southwesterly flow brought by the strong Caspian Sea trough, supplying the warm air constantly. There was a strong and steady high existed in the front of the Urals blocking high and the frequent activities of trough, bringing cold air to the western China, which resulted in the freezing disaster in Guizhou region.
The NCEP/NCAR reanalysis data (1°×1°，6 h) in January 2011 and the observation data in winter from 1970 to 2011 provided by Guizhou Meteorological Service are used to investigate the climatic characteristics of freezing disaster occurred in January 2011 and its causes by climate statistics and climate diagnostic methods. More than 34 stations reached the lowest temperature in the past 40 years during the freezing rain event. There were active blocking anticyclones near the Ural Mountains persistently, which were more active than the normal. They were broken down twice and rebuilt thrice, with the wet southwesterly flow brought by the strong Caspian Sea trough, supplying the warm air constantly. There was a strong and steady high existed in the front of the Urals blocking high and the frequent activities of trough, bringing cold air to the western China, which resulted in the freezing disaster in Guizhou region.
2013, 41(6):1122-1127.
Abstract:
Crop growth parameters are important data for describing crop growth and evaluating environmental conditions (including agrometeorological disasters) influencing crop growth, and also the important basis to predict crop yields and guide farm management. The research progresses and the application of automatic observation techniques for crop growth at home and abroad are discussed, focusing on plant heights, crop coverages, crop growth periods, and other characteristic parameters, and the principles, methods, feasibility and limitations of the related technologies are explored. The analysis shows that computer vision image processing technology, based on crop pictures from CCD sensors, can be used to obtain morphological characteristics, coverage, developmental stages, and leaves color of crops more accurately, fast, and visually, which is the basis of the verification of the crop growth conditions estimated by satellite remote sensing and the automatic monitoring of damages by diseases and insects on crops, as well as the supply of nutrients to crop, and shows good prospects.
Crop growth parameters are important data for describing crop growth and evaluating environmental conditions (including agrometeorological disasters) influencing crop growth, and also the important basis to predict crop yields and guide farm management. The research progresses and the application of automatic observation techniques for crop growth at home and abroad are discussed, focusing on plant heights, crop coverages, crop growth periods, and other characteristic parameters, and the principles, methods, feasibility and limitations of the related technologies are explored. The analysis shows that computer vision image processing technology, based on crop pictures from CCD sensors, can be used to obtain morphological characteristics, coverage, developmental stages, and leaves color of crops more accurately, fast, and visually, which is the basis of the verification of the crop growth conditions estimated by satellite remote sensing and the automatic monitoring of damages by diseases and insects on crops, as well as the supply of nutrients to crop, and shows good prospects.
2013, 41(6):1128-1133.
Abstract:
In order to study the effects of different relative humidity on the leaf photosynthesis characteristic in a greenhouse, an experiment was conducted with eight models of relative humidity on cucumber Jinyou 1, which was chosen as the trail material. The photosynthetic physiology parameters of cucumber leaves were measured with the LI 6400 portable photosynthesis system. The results show that the net photosynthetic rate and intercellular CO2 concentration reduced with the decreasing relative humidity; the stomata conductance, transpiration rate, and the leaf water use efficiency reached the maximum when relative humidity was 75%, while the stomatal limitation value reached the minimum when relative humidity was 75%. The relationship of maximum photosynthetic rate and air relative humidity conforms to the exponent equation: 〖WTBX〗P〖WTBZ〗max=223753e189085fRH. Through the light response curves, it can be learned that the apparent photosynthetic quantum yield and light saturation decrease with deceasing relative humidity, and the light compensation point increases with the decreasing relative humidity. In addition, the correlative analysis indicates that a negative correlation between the vapor pressure deficit of leaves and relative humidity, and a positive correlation exists between intercellular CO2 concentration, stomata conductance transpiration rate, relative humidity, and photosynthetic rate.
In order to study the effects of different relative humidity on the leaf photosynthesis characteristic in a greenhouse, an experiment was conducted with eight models of relative humidity on cucumber Jinyou 1, which was chosen as the trail material. The photosynthetic physiology parameters of cucumber leaves were measured with the LI 6400 portable photosynthesis system. The results show that the net photosynthetic rate and intercellular CO2 concentration reduced with the decreasing relative humidity; the stomata conductance, transpiration rate, and the leaf water use efficiency reached the maximum when relative humidity was 75%, while the stomatal limitation value reached the minimum when relative humidity was 75%. The relationship of maximum photosynthetic rate and air relative humidity conforms to the exponent equation: 〖WTBX〗P〖WTBZ〗max=223753e189085fRH. Through the light response curves, it can be learned that the apparent photosynthetic quantum yield and light saturation decrease with deceasing relative humidity, and the light compensation point increases with the decreasing relative humidity. In addition, the correlative analysis indicates that a negative correlation between the vapor pressure deficit of leaves and relative humidity, and a positive correlation exists between intercellular CO2 concentration, stomata conductance transpiration rate, relative humidity, and photosynthetic rate.
30 Application of AHP Based Fuzzy Comprehensive Evaluation in Climate Regionalization for Tea Planting
2013, 41(6):1134-1137.
Abstract:
Taking the planting area of the tea Xinyang Maojian as an example, using the Analytic Hierarchy Process (AHP) to determine the zoning index weight, combined with the fuzzy comprehensive evaluation method, the fuzzy membership function and the fuzzy membership of the weighted average are calculated, and then the comprehensive regionalization index is obtained, thus to conduct the agricultural climate regionalization of the tea planting area. The results show that the comprehensive indexes in Xinyang, Gushi, Shangcheng, Xinxian, Jigongshan Mountain, etc., are greater than or equal to 0.60, belonging to the suitable planting area; those in Luoshan and Guangshan are between 0.45 and 0.59, belonging to the sub suitable planting area, in which the planting area of Xinyang Maojian is large, but the quality is slightly inferior to the suitable planting areas. Xixian, Huaibin, and Huangchuan, with index value being less than 0.45, are not suitable for planting tea, in which the tea planting area is small, and the tea quality is poor.
Taking the planting area of the tea Xinyang Maojian as an example, using the Analytic Hierarchy Process (AHP) to determine the zoning index weight, combined with the fuzzy comprehensive evaluation method, the fuzzy membership function and the fuzzy membership of the weighted average are calculated, and then the comprehensive regionalization index is obtained, thus to conduct the agricultural climate regionalization of the tea planting area. The results show that the comprehensive indexes in Xinyang, Gushi, Shangcheng, Xinxian, Jigongshan Mountain, etc., are greater than or equal to 0.60, belonging to the suitable planting area; those in Luoshan and Guangshan are between 0.45 and 0.59, belonging to the sub suitable planting area, in which the planting area of Xinyang Maojian is large, but the quality is slightly inferior to the suitable planting areas. Xixian, Huaibin, and Huangchuan, with index value being less than 0.45, are not suitable for planting tea, in which the tea planting area is small, and the tea quality is poor.
2013, 41(6):1138-1146.
Abstract:
According to the data of acid rains in 7 stations over Hangzhou from July 2009 to June 2012 and their relationships with the atmosphere composition, analyses are made of the trend and distribution characteristics of acid rains in Hangzhou during the recent three years, and the different meteorological conditions and the influence of air pollutant on acid rains are investigated. The result reveals that the average pH of precipitation is between 437 and 523 during recent three years; the degree of acid rain pollution is more serious in the west part and less serious in the east of Hangzhou;the precipitation acidity and the frequency of acid rain show a small fluctuation, but the trend is not obvious in general; the pollution level of acid rains is lowest in summer, highest in autumn and winter, and moderate in spring. The relationship between precipitation intensity and pH and K varies from one station to the other: there is a positive relationship between precipitation intensity and pH in the stations of Linan, Chunan, Jiande, and Fuyang, and the relationship between precipitation intensity and pH in stations of Hangzhou and Tonglu is not obvious.Particularly, there is a negative relationship between conductivity and precipitation intensity for all stations. Under the influence of the north wind at 850 hPa, the precipitation acidity is more severe and the conductivity is higher. The pH of precipitation is positively related to the height of the inverse temperature at lower levels and negatively related to the thickness of the inverse temperature. Severe haze weather always accompanies the strong acid rains during the early half stage of the precipitation. The relationship between inverse temperature and conductivity of precipitation is not obvious. There is a significant negative correlation between the concentration of atmospheric pollutants, such as SO2, NO2 and PM25, and the pH of rain water, suggesting that the variation of pollutant concentration in the lower atmosphere layer has significant influence on acid rains.
According to the data of acid rains in 7 stations over Hangzhou from July 2009 to June 2012 and their relationships with the atmosphere composition, analyses are made of the trend and distribution characteristics of acid rains in Hangzhou during the recent three years, and the different meteorological conditions and the influence of air pollutant on acid rains are investigated. The result reveals that the average pH of precipitation is between 437 and 523 during recent three years; the degree of acid rain pollution is more serious in the west part and less serious in the east of Hangzhou;the precipitation acidity and the frequency of acid rain show a small fluctuation, but the trend is not obvious in general; the pollution level of acid rains is lowest in summer, highest in autumn and winter, and moderate in spring. The relationship between precipitation intensity and pH and K varies from one station to the other: there is a positive relationship between precipitation intensity and pH in the stations of Linan, Chunan, Jiande, and Fuyang, and the relationship between precipitation intensity and pH in stations of Hangzhou and Tonglu is not obvious.Particularly, there is a negative relationship between conductivity and precipitation intensity for all stations. Under the influence of the north wind at 850 hPa, the precipitation acidity is more severe and the conductivity is higher. The pH of precipitation is positively related to the height of the inverse temperature at lower levels and negatively related to the thickness of the inverse temperature. Severe haze weather always accompanies the strong acid rains during the early half stage of the precipitation. The relationship between inverse temperature and conductivity of precipitation is not obvious. There is a significant negative correlation between the concentration of atmospheric pollutants, such as SO2, NO2 and PM25, and the pH of rain water, suggesting that the variation of pollutant concentration in the lower atmosphere layer has significant influence on acid rains.
32 Comprehensive Analysis of Two Heavy Haze Events Induced by Straw Burning in Central Eastern Hubei
2013, 41(6):1147-1152.
Abstract:
By means of the relative humidity data from meteorological satellite, microwave radiometer, and regular meteorological observations, as well as NCEP reanalysis data and environmental monitoring data, through air flow backward trajectory simulation, the characteristics and causes of two haze weather events in 11 and 15 June 2012 over the eastern Hubei are analyzed. The results show that the pollution indexes (API) are 233 μg/m3 and 139 μg/m3, respectively, with the highest PM2.5 being 141 μg/m3 in 11 June; the visibility in the two days is below 2000 m, with the average visibility being only 565 m in 11 June and the minimum visibility 246 m. The two heavy haze events are closely related to the concentrated straw burning over the region, where is one of the main winter wheat producing areas in China. There existed a large range of temperature inversion layer around 115°E, 39° to 32°N; the vertical height of 950 to 850 hPa thickness was consistent with the northeast flow, so that the pollutant cannot diffuse into the air and transmit to the eastern Hubei with Northeast flow. At the same time, because of calm wind, uniform pressure field, temperature inversion, weak vertical shear, positive vorticity, negative divergence, and suitable humidity conditions, pollutants cannot be timely diffused or subsided, which is favorable for haze formation and aggravation.
By means of the relative humidity data from meteorological satellite, microwave radiometer, and regular meteorological observations, as well as NCEP reanalysis data and environmental monitoring data, through air flow backward trajectory simulation, the characteristics and causes of two haze weather events in 11 and 15 June 2012 over the eastern Hubei are analyzed. The results show that the pollution indexes (API) are 233 μg/m3 and 139 μg/m3, respectively, with the highest PM2.5 being 141 μg/m3 in 11 June; the visibility in the two days is below 2000 m, with the average visibility being only 565 m in 11 June and the minimum visibility 246 m. The two heavy haze events are closely related to the concentrated straw burning over the region, where is one of the main winter wheat producing areas in China. There existed a large range of temperature inversion layer around 115°E, 39° to 32°N; the vertical height of 950 to 850 hPa thickness was consistent with the northeast flow, so that the pollutant cannot diffuse into the air and transmit to the eastern Hubei with Northeast flow. At the same time, because of calm wind, uniform pressure field, temperature inversion, weak vertical shear, positive vorticity, negative divergence, and suitable humidity conditions, pollutants cannot be timely diffused or subsided, which is favorable for haze formation and aggravation.
2013, 41(6):1153-1160.
Abstract:
The characteristics of space time variation, direction distribution, and gradient change of wind velocity and wind power density near the surface are analyzed, using the 10 minute wind observation data of different altitudes (10, 30, 50, 70 m) from May to October in 2009 from the China Wind Energy Resources Professional Observation Network. The results show that: (1) the average wind power density in China is 1652 W/m2, and wind resources in Northwest China and Southeast coastal areas are more plentiful; (2) exploitable wind resources in May and October are more abundant relatively, with the maximum in May over the northern China, while in October over the southern China; (3) wind direction distribution presents a regular trend: northwestly wind prevails in Northwest, Northeast and North China, while southeastly wind reigns in the eastern coaster areas, and southwestly wind predominates in Yunnan and Guizhou; (4) in terms of wind gradient distribution, the developable wind resources of higher altitudes are more abundant; (5) in terms of daily wind variation, wind resources are more plentiful from 08:00 to 20:00, with average wind velocity and wind power density maximizing at 15:00 every day, and however, wind resources distribution differs in different areas and at different times. This study can provide some technical references in building wind farms and making use of near surface wind resources in China.
The characteristics of space time variation, direction distribution, and gradient change of wind velocity and wind power density near the surface are analyzed, using the 10 minute wind observation data of different altitudes (10, 30, 50, 70 m) from May to October in 2009 from the China Wind Energy Resources Professional Observation Network. The results show that: (1) the average wind power density in China is 1652 W/m2, and wind resources in Northwest China and Southeast coastal areas are more plentiful; (2) exploitable wind resources in May and October are more abundant relatively, with the maximum in May over the northern China, while in October over the southern China; (3) wind direction distribution presents a regular trend: northwestly wind prevails in Northwest, Northeast and North China, while southeastly wind reigns in the eastern coaster areas, and southwestly wind predominates in Yunnan and Guizhou; (4) in terms of wind gradient distribution, the developable wind resources of higher altitudes are more abundant; (5) in terms of daily wind variation, wind resources are more plentiful from 08:00 to 20:00, with average wind velocity and wind power density maximizing at 15:00 every day, and however, wind resources distribution differs in different areas and at different times. This study can provide some technical references in building wind farms and making use of near surface wind resources in China.
External LinksChina Meteorological AdministrationCMA Meteorological Observation CentreChinese Academy of Meteorological SciencesBeijing Meteorological ServiceNational Satellite Meteorological Center
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.