Volume 42,Issue 1,2014 Table of Contents
2014, 42(1):1-12.
Abstract:
Along with the development of the numerical computational method and high performance computer technology and the improvement of atmospheric science theory, many high resolution global nonhydrostatic atmospheric numerical models have been developed abroad by many country communities. In order to make domestic model developers clearly understand the current status of global atmospheric numerical models, the properties of the 17 global nonhydrostatic atmospheric numerical models participating in the performance assessment at the National Center for Atmospheric Research of the United States in August 2012 are summarized and discussed, mainly from the aspects of the basic equations, spherical grid, discretization method, conservation and coupling strategy between the parameterized physical processes, and the dynamic frameworks and evaluation of global atmospheric models. The results have certain reference significance for domestic model developers.
Along with the development of the numerical computational method and high performance computer technology and the improvement of atmospheric science theory, many high resolution global nonhydrostatic atmospheric numerical models have been developed abroad by many country communities. In order to make domestic model developers clearly understand the current status of global atmospheric numerical models, the properties of the 17 global nonhydrostatic atmospheric numerical models participating in the performance assessment at the National Center for Atmospheric Research of the United States in August 2012 are summarized and discussed, mainly from the aspects of the basic equations, spherical grid, discretization method, conservation and coupling strategy between the parameterized physical processes, and the dynamic frameworks and evaluation of global atmospheric models. The results have certain reference significance for domestic model developers.
2014, 42(1):13-22.
Abstract:
Some issues with regard to spherical Yin Yang grids are reviewed, such as transformation relationship, advantages and disadvantages, and the data interpolation exchange method in the overlapping boundaries. Also three numerical methods, including the optimized Schwarz method, CIP CSLR advection numerical method, and multi moment finite volume method which has been implemented on the spherical overset Yin Yang grids, are discussed and summarized. For the optimized Schwarz method, the advantages of solving the spherical elliptic problem are discussed from the aspect of the discretization of the shallow water equations. For the CIP CSLR advection numerical method and multi moment finite volume method, the analysis is mainly conducted about how to construct the interpolation functions in the grid cells. The development of the global nonhydrostatic Yin Yang grid model is prospected.
Some issues with regard to spherical Yin Yang grids are reviewed, such as transformation relationship, advantages and disadvantages, and the data interpolation exchange method in the overlapping boundaries. Also three numerical methods, including the optimized Schwarz method, CIP CSLR advection numerical method, and multi moment finite volume method which has been implemented on the spherical overset Yin Yang grids, are discussed and summarized. For the optimized Schwarz method, the advantages of solving the spherical elliptic problem are discussed from the aspect of the discretization of the shallow water equations. For the CIP CSLR advection numerical method and multi moment finite volume method, the analysis is mainly conducted about how to construct the interpolation functions in the grid cells. The development of the global nonhydrostatic Yin Yang grid model is prospected.
2014, 42(1):23-30.
Abstract:
In the past decades, plentiful outcomes were achieved in all aspects of fog researches in China. The recent development and outcomes in this field are summarized and generalized, including the studies of the characteristics of fogs using the climatological statistical method, the mechanisms of fogs by using the numerical simulation method, the microphysical structure of fogs, as well as the studies of the monitoring, recognition and forecasting techniques of fogs. On this basis, hot topics in the current and possible research areas in the future are analyzed, including researches on the fogs on highway, hazes, interaction between fogs and urbanization, and fogs in coastal areas and areas with complex terrain.
In the past decades, plentiful outcomes were achieved in all aspects of fog researches in China. The recent development and outcomes in this field are summarized and generalized, including the studies of the characteristics of fogs using the climatological statistical method, the mechanisms of fogs by using the numerical simulation method, the microphysical structure of fogs, as well as the studies of the monitoring, recognition and forecasting techniques of fogs. On this basis, hot topics in the current and possible research areas in the future are analyzed, including researches on the fogs on highway, hazes, interaction between fogs and urbanization, and fogs in coastal areas and areas with complex terrain.
2014, 42(1):31-37.
Abstract:
A total of 3211 fault cases of Doppler weather radar of various models in recent 5 years are classified and analyzed for 9 radar subsystems. The results indicate that it is necessary for these that work under high voltage for a long time and are vulnerable, to burnout to strengthen the backup of spare parts and improve the reliability of these spare parts and to improve the reliability and resistance to pressure. Moreover, the machine room environment should have constant temperature and humidity, as well as dust proof to keep radar operating normally. It is also important to clean carbon dusts in the motor and maintain and clean the collector ring to prevent carbon brush abrasion and damage. Meanwhile, regular maintenance of the mechanical devices under high/low temperature environment for a long time is also needed in order to improve the reliability of moving parts. The power supply and data communication with external users are also important.
A total of 3211 fault cases of Doppler weather radar of various models in recent 5 years are classified and analyzed for 9 radar subsystems. The results indicate that it is necessary for these that work under high voltage for a long time and are vulnerable, to burnout to strengthen the backup of spare parts and improve the reliability of these spare parts and to improve the reliability and resistance to pressure. Moreover, the machine room environment should have constant temperature and humidity, as well as dust proof to keep radar operating normally. It is also important to clean carbon dusts in the motor and maintain and clean the collector ring to prevent carbon brush abrasion and damage. Meanwhile, regular maintenance of the mechanical devices under high/low temperature environment for a long time is also needed in order to improve the reliability of moving parts. The power supply and data communication with external users are also important.
2014, 42(1):38-41.
Abstract:
The five beam observation data of the GLC 24 wind profiler are used to analyze the detection accuracy of wind profilers under clear and precipitation conditions, respectively. The results show that in clear weather wind profilers have a high detection accuracy on horizontal winds because the atmosphere is uniform and steady with a small vertical speed, while under the condition of uniform precipitation, even with a large vertical speed, wind profilers also have a good detection accuracy on horizontal winds because the atmosphere was relatively uniform within the detecting range of five beams, and under the condition of no uniform precipitation, in which the assumption of horizontal wind calculation of the wind profiler is unsatisfied, the algorithm should be improved to reduce calculating errors.
The five beam observation data of the GLC 24 wind profiler are used to analyze the detection accuracy of wind profilers under clear and precipitation conditions, respectively. The results show that in clear weather wind profilers have a high detection accuracy on horizontal winds because the atmosphere is uniform and steady with a small vertical speed, while under the condition of uniform precipitation, even with a large vertical speed, wind profilers also have a good detection accuracy on horizontal winds because the atmosphere was relatively uniform within the detecting range of five beams, and under the condition of no uniform precipitation, in which the assumption of horizontal wind calculation of the wind profiler is unsatisfied, the algorithm should be improved to reduce calculating errors.
2014, 42(1):42-47.
Abstract:
A comparative assessment is made of the observation data from the L band radar sounding system and 701 400M sounding system at Dazhou Station in Sichuan. The results indicate that the average temperature difference is -028 ℃; that below 200 hPa height is -005 ℃, and that above 200 hPa height is -052 ℃. The temperature data change resulted from sounding system change is obvious; 801% of temperature differences are between －10 ℃ and 10 ℃. The average geopotential height difference is -763 gpm; that below 100 hPa height is -113 gpm, and that above 100 hPa height is -1957 gpm. The geopotential height data change resulted from sounding system change is obvious; 890% of geopotential height difference is between -50 gpm and 10 gpm. The average relative humidity difference is -2%; 872% of relative humidity differences are between -20% and 10%. The average wind direction difference is 10°; 801% of the differences, are between -10° and 10°. The average wind velocity difference is 03 m/s; 95% of wind velocity differencs are between -5 m/s and 5 m/s. According to the average differences, the temperature, geopotential height, and relative humidity measurements from the L band sounding system are 〖JP2〗lower than those measured by the 701 400 M sounding system, but wind direction and velocity measurements from the L band sounding system are higher than those measured by the 701 400 M sounding system. The peak difference is large because of sounding system change. Owing to the differences of equipment, sounder manufacturing, measurement accuracy, sounder launching, message receiving, etc., the observational data are different, but influences on various elements are different.
A comparative assessment is made of the observation data from the L band radar sounding system and 701 400M sounding system at Dazhou Station in Sichuan. The results indicate that the average temperature difference is -028 ℃; that below 200 hPa height is -005 ℃, and that above 200 hPa height is -052 ℃. The temperature data change resulted from sounding system change is obvious; 801% of temperature differences are between －10 ℃ and 10 ℃. The average geopotential height difference is -763 gpm; that below 100 hPa height is -113 gpm, and that above 100 hPa height is -1957 gpm. The geopotential height data change resulted from sounding system change is obvious; 890% of geopotential height difference is between -50 gpm and 10 gpm. The average relative humidity difference is -2%; 872% of relative humidity differences are between -20% and 10%. The average wind direction difference is 10°; 801% of the differences, are between -10° and 10°. The average wind velocity difference is 03 m/s; 95% of wind velocity differencs are between -5 m/s and 5 m/s. According to the average differences, the temperature, geopotential height, and relative humidity measurements from the L band sounding system are 〖JP2〗lower than those measured by the 701 400 M sounding system, but wind direction and velocity measurements from the L band sounding system are higher than those measured by the 701 400 M sounding system. The peak difference is large because of sounding system change. Owing to the differences of equipment, sounder manufacturing, measurement accuracy, sounder launching, message receiving, etc., the observational data are different, but influences on various elements are different.
2014, 42(1):48-53.
Abstract:
Based on the wind profiler radar working principles and wind formulas, the main factors affecting atmospheric wind field observation errors are studied, and the effect of radar echo signal to noise ratio (SNR) on wind observation accuracy and GPS sounding comparison test is analyzed. The conclusions are as follows: (1) Wind speed observation accuracy is mainly depended on the beam tilt angle, radar technical parameters, and the vertical distribution of 〖WTBX〗C〖WTBZ〗n2 (refractive index structure parameter); the greater the wind speed and wind speed accuracy, the greater the accuracy of wind direction. (2) In the same observation mode, the greater the beam tilt angle and 〖WTBX〗C〖WTBZ〗n2, the higher the accuracy of the wind field observations. (3) The greater radar echo SNR, the smaller the accuracy of wind speed. There is large difference in wind observation error between different modes. (4) There is good correlation between wind speed and direction in the comparative test, but the relative deviation is obvious, especially at low altitudes.
Based on the wind profiler radar working principles and wind formulas, the main factors affecting atmospheric wind field observation errors are studied, and the effect of radar echo signal to noise ratio (SNR) on wind observation accuracy and GPS sounding comparison test is analyzed. The conclusions are as follows: (1) Wind speed observation accuracy is mainly depended on the beam tilt angle, radar technical parameters, and the vertical distribution of 〖WTBX〗C〖WTBZ〗n2 (refractive index structure parameter); the greater the wind speed and wind speed accuracy, the greater the accuracy of wind direction. (2) In the same observation mode, the greater the beam tilt angle and 〖WTBX〗C〖WTBZ〗n2, the higher the accuracy of the wind field observations. (3) The greater radar echo SNR, the smaller the accuracy of wind speed. There is large difference in wind observation error between different modes. (4) There is good correlation between wind speed and direction in the comparative test, but the relative deviation is obvious, especially at low altitudes.
2014, 42(1):54-61.
Abstract:
There are some inevitable interferences in the polar orbit meteorological satellites link budget, among which rainfall attenuation plays a vital role. On the basis of communication link design theory, a rainfall attenuation simulation model is presented. Through MATLAB simulation for national polar orbit meteorological satellite receiving ground stations, the factors influencing rainfall attenuation are discussed, such as rainfall intensity, antenna elevation, frequency, and polarization angle. The results can be used as references in solving the problems about the communication link and the design of ground data receiving system.
There are some inevitable interferences in the polar orbit meteorological satellites link budget, among which rainfall attenuation plays a vital role. On the basis of communication link design theory, a rainfall attenuation simulation model is presented. Through MATLAB simulation for national polar orbit meteorological satellite receiving ground stations, the factors influencing rainfall attenuation are discussed, such as rainfall intensity, antenna elevation, frequency, and polarization angle. The results can be used as references in solving the problems about the communication link and the design of ground data receiving system.
Dang Xuanfa
,
Huang Rui
,
Liu Yongqiang
,
Zhang Hongying
,
Yao Aiguo
,
Wu Anbang
,
Wu Ning
,
Han Yuting
2014, 42(1):62-67.
Abstract:
Analysis, evaluation, and comparison are conducted on the test results from five metrological laboratories over Northwest China to find problems and summarize experiences timely, so to improve the laboratory’s test/calibration capability and quality management level. Comparative experiments are conducted on the pressure, temperature, humidity, and wind speed samples from the five metrological laboratories, respectively, and a statistical analysis is carried out by means of the 〖WTBX〗E〖WTBZ〗n (normalized deviation) method. The comparison results of temperature, humidity, and air pressure from metrological laboratories over Northwest China are very satisfactory, and that of wind speed is satisfactory. The comparison test data is objective, realistic and credible. The experiment is a comprehensive evaluation of test/calibration capability of metrological laboratories, can reflect the technical level of the test/calibration personnel and the current situation of meteorological metrological standard equipment objectively.
Analysis, evaluation, and comparison are conducted on the test results from five metrological laboratories over Northwest China to find problems and summarize experiences timely, so to improve the laboratory’s test/calibration capability and quality management level. Comparative experiments are conducted on the pressure, temperature, humidity, and wind speed samples from the five metrological laboratories, respectively, and a statistical analysis is carried out by means of the 〖WTBX〗E〖WTBZ〗n (normalized deviation) method. The comparison results of temperature, humidity, and air pressure from metrological laboratories over Northwest China are very satisfactory, and that of wind speed is satisfactory. The comparison test data is objective, realistic and credible. The experiment is a comprehensive evaluation of test/calibration capability of metrological laboratories, can reflect the technical level of the test/calibration personnel and the current situation of meteorological metrological standard equipment objectively.
Xia Dong
,
Wu Zhiquan
,
Tan Haobo
,
Yuan Zhiyang
,
Chen Ling
,
Huang Peiguang
,
Yin Shuxian
,
Luo Kun
2014, 42(1):68-72.
Abstract:
The measurements of visibility sensors from 22 stations of the Guangdong Automatic Observing System of Visibility are analyzed by compared with the manual observation data of visibility. The results show that the visibility from two approaches had a similar distribution in Guangdong: visibility in coastal areas is higher than that in inland areas; visibility in the east is higher than that in the west; and the Pearl River Delta and the eastern inland have the lowest visibility in Guangdong. The reasons affecting the accuracy of automatic visibility observation include the limitation of visibility sensors, the types of aerosols, and meteorological conditions. After correcting, RMS is smaller than 3 km when the visibility is low, and smaller than 8 km (the mean value is about 6 km) when the visibility is high. Using the statistic method to correct the measurements of the visibility sensor helps reduce metrical errors effectively. After correcting, the Visibility Automatic Observing System in Guangdong can satisfy the needs of automatic observation, especially for low visibility events.
The measurements of visibility sensors from 22 stations of the Guangdong Automatic Observing System of Visibility are analyzed by compared with the manual observation data of visibility. The results show that the visibility from two approaches had a similar distribution in Guangdong: visibility in coastal areas is higher than that in inland areas; visibility in the east is higher than that in the west; and the Pearl River Delta and the eastern inland have the lowest visibility in Guangdong. The reasons affecting the accuracy of automatic visibility observation include the limitation of visibility sensors, the types of aerosols, and meteorological conditions. After correcting, RMS is smaller than 3 km when the visibility is low, and smaller than 8 km (the mean value is about 6 km) when the visibility is high. Using the statistic method to correct the measurements of the visibility sensor helps reduce metrical errors effectively. After correcting, the Visibility Automatic Observing System in Guangdong can satisfy the needs of automatic observation, especially for low visibility events.
2014, 42(1):73-76.
Abstract:
Considering the comparison schemes, resources of reference values, methods of comparison result evaluation, and comparison reports in organizing and conducting comparison activities between laboratories in meteorological metrological verification institutes, the capabilities of the meteorological metrological laboratories are evaluated. The significance of the meteorological metrological verification institutes in professional metrological verification is discussed through comparison between meteorological metrological laboratories. Comparison is an important method used in measurement capability verification for laboratories. The atmospheric pressure quantity value comparison project carried out by the National Center for Meteorological Metrology, as the pilot laboratory, and organized by the meteorological branch technical committee of the National Pressure Metrological Technical Committee in 2011 is introduced. Eight laboratories were participated in the comparison project, and the star type method is used in the comparison. The normalized deviations of the 〖WTBX〗E〖WTBZ〗n value method are used for the evaluation of comparison results. The comparison results indicate that all the uncertainties of measurement results claimed by participating laboratories are reliable.
Considering the comparison schemes, resources of reference values, methods of comparison result evaluation, and comparison reports in organizing and conducting comparison activities between laboratories in meteorological metrological verification institutes, the capabilities of the meteorological metrological laboratories are evaluated. The significance of the meteorological metrological verification institutes in professional metrological verification is discussed through comparison between meteorological metrological laboratories. Comparison is an important method used in measurement capability verification for laboratories. The atmospheric pressure quantity value comparison project carried out by the National Center for Meteorological Metrology, as the pilot laboratory, and organized by the meteorological branch technical committee of the National Pressure Metrological Technical Committee in 2011 is introduced. Eight laboratories were participated in the comparison project, and the star type method is used in the comparison. The normalized deviations of the 〖WTBX〗E〖WTBZ〗n value method are used for the evaluation of comparison results. The comparison results indicate that all the uncertainties of measurement results claimed by participating laboratories are reliable.
2014, 42(1):77-82.
Abstract:
According to the related requirements of the China Meteorological Administration, in order to improve the working efficiency of ground meteorological observation and to optimize operating procedures, as one of the pilot reform provinces in 2011, after the pilot adjustment of some station, the Hubei Provincial Meteorological Service adjusted the reporting and transmitting modes of ground meteorological observation data for all the national observation stations. After the adjustment, the operational service is carrying out well. The procedures and methods for the implementation of adjustment are introduced from the aspects of the significance to practical work, the deployment of operational service, the new format of data files, quality control methods, and the function features of the revised software.
According to the related requirements of the China Meteorological Administration, in order to improve the working efficiency of ground meteorological observation and to optimize operating procedures, as one of the pilot reform provinces in 2011, after the pilot adjustment of some station, the Hubei Provincial Meteorological Service adjusted the reporting and transmitting modes of ground meteorological observation data for all the national observation stations. After the adjustment, the operational service is carrying out well. The procedures and methods for the implementation of adjustment are introduced from the aspects of the significance to practical work, the deployment of operational service, the new format of data files, quality control methods, and the function features of the revised software.
2014, 42(1):83-88.
Abstract:
The development and construction of meteorological service systems are the foundation to achieve a high quality meteorological service. According to the lagging situation of the meteorological service system, based on the characteristics of meteorological service, three dimensional geographic information system （3DGIS）technology is applied to the construction of a meteorological service system, Global Weather Analysis Service System (GWASS). GWASS can satisfy the processing and analyzing of meteorological information based on GIS, and aid the meteorological service product making, displaying, and outputting, which provides a basic platform for meteorological service and performs well in application. The design and implementation of GWASS are introduced; the overall architecture design and hierarchical design, as well as the functions and effects of the core subsystem and functional subsystems, are described based on Microsoft “.net” platform; and the key techniques of 3DGIS applied to weather service are analyzed. An application example of GWASS is given.
The development and construction of meteorological service systems are the foundation to achieve a high quality meteorological service. According to the lagging situation of the meteorological service system, based on the characteristics of meteorological service, three dimensional geographic information system （3DGIS）technology is applied to the construction of a meteorological service system, Global Weather Analysis Service System (GWASS). GWASS can satisfy the processing and analyzing of meteorological information based on GIS, and aid the meteorological service product making, displaying, and outputting, which provides a basic platform for meteorological service and performs well in application. The design and implementation of GWASS are introduced; the overall architecture design and hierarchical design, as well as the functions and effects of the core subsystem and functional subsystems, are described based on Microsoft “.net” platform; and the key techniques of 3DGIS applied to weather service are analyzed. An application example of GWASS is given.
2014, 42(1):89-93.
Abstract:
In order to improve the accuracy and timeliness of meteorological early warning information, realize the small area fine early warning of meteorological disasters, and give full play to the role of early warning information in disaster prevention and mitigation, the data of the national meteorological stations, regional automatic stations, mountain torrent precipitation stations, and lightning location systems in the Beibei area are used to develop the fined meteorological disaster early warning system with data quality control, multi threshold and targeted warning phraseology, by means of “.net” SQL server and ArcGIS as the platform. The system has both manual warning and automatic warning functions. Application of the system provides more timely and accurate early warning information to public.
In order to improve the accuracy and timeliness of meteorological early warning information, realize the small area fine early warning of meteorological disasters, and give full play to the role of early warning information in disaster prevention and mitigation, the data of the national meteorological stations, regional automatic stations, mountain torrent precipitation stations, and lightning location systems in the Beibei area are used to develop the fined meteorological disaster early warning system with data quality control, multi threshold and targeted warning phraseology, by means of “.net” SQL server and ArcGIS as the platform. The system has both manual warning and automatic warning functions. Application of the system provides more timely and accurate early warning information to public.
2014, 42(1):94-98.
Abstract:
A sea fog search database, which contains and organizes cases in the offshore area of China in latest 10 years, was accomplished. From the database, the related case data could be browsed and downloaded by forecasters and researchers for their own purposes which require various case information, such as surface or satellite observations and reanalysis data, under different search conditions. This database supplies comprehensive and detailed analysis data for sea fog researches.
A sea fog search database, which contains and organizes cases in the offshore area of China in latest 10 years, was accomplished. From the database, the related case data could be browsed and downloaded by forecasters and researchers for their own purposes which require various case information, such as surface or satellite observations and reanalysis data, under different search conditions. This database supplies comprehensive and detailed analysis data for sea fog researches.
2014, 42(1):99-103.
Abstract:
Using programs such as java, C#, VB, and Delphi, a mobile meteorological information service platform based on Android smartphone technology is developed, which enriches meteorological information service approaches and enhances service capability. Focused on user experiences, the platform provides an innovative mobile meteorological information service approach for public users, combining the features of Android smartphones and mobile applications. The platform is an integrated system consisting of three modules: the processing, distribution, and reception of meteorological information, through which users can acquire meteorological information at any time. The design of the platform architecture and client applications of this platform are introduced. The problems and solutions involved in the R&D process of Android client applications with Java are elaborated. Issues such as gesture control, GIS service, application management, system compatibility, and stability, are also discussed in detail.
Using programs such as java, C#, VB, and Delphi, a mobile meteorological information service platform based on Android smartphone technology is developed, which enriches meteorological information service approaches and enhances service capability. Focused on user experiences, the platform provides an innovative mobile meteorological information service approach for public users, combining the features of Android smartphones and mobile applications. The platform is an integrated system consisting of three modules: the processing, distribution, and reception of meteorological information, through which users can acquire meteorological information at any time. The design of the platform architecture and client applications of this platform are introduced. The problems and solutions involved in the R&D process of Android client applications with Java are elaborated. Issues such as gesture control, GIS service, application management, system compatibility, and stability, are also discussed in detail.
2014, 42(1):104-109.
Abstract:
Based on the ERA 40 sea surface 10 m wind field data of the European Centre for Medium Range Weather Forecasts (ECMWF), the change trends of the global sea surface wind speed from 1958 to 2001 are analyzed, mainly including the overall change trend, seasonal differences, regional differences, and change cycles. The result indicates: (1) Global sea surface wind speed increased significantly and linearly with a rate of 00067 m〖DK〗·s-1〖DK〗·a-1 year by year during the recent 44 years; the change of global sea surface wind speed is relatively gentle in the period of 1958 to 1975 and relatively sharp in the period of 1975 to 1983 The peak and valley of the annual mean global sea surface wind speed appeared in 1999 and 1975, respectively. (2) The change trends of global sea surface wind speed showed significant regional differences. The areas with an obvious increasing trend are mainly distributed in the Antarctic region, tropical Atlantic and North Pacific westerly zone waters, low latitudes in the Indian Ocean, and the regions near 60°S in the Southern Hemisphere, especially with the strongest increasing trend in the Southern Hemisphere high latitude waters; significantly decreasing areas are mainly distributed in the regions near the equatorial Middle East Pacific, Juan Fernandez Islands, the south westerly zone in the central Atlantic Ocean, as well as some sporadic waters. (3) The change trends of global sea surface wind speed showed significant seasonal differences with a significant linear increasing trend for all months. The sharpest increasing trend is in December (00103 m〖DK〗·s-1〖DK〗·a-1), and the gentlest increasing trend is in July (approximately 00033 m〖DK〗·s-1〖DK〗·a-1). (4) There is obvious periodic change in Global ocean sea surface wind speed with the periods being 22 to 43 years, as well as 65 years.
Based on the ERA 40 sea surface 10 m wind field data of the European Centre for Medium Range Weather Forecasts (ECMWF), the change trends of the global sea surface wind speed from 1958 to 2001 are analyzed, mainly including the overall change trend, seasonal differences, regional differences, and change cycles. The result indicates: (1) Global sea surface wind speed increased significantly and linearly with a rate of 00067 m〖DK〗·s-1〖DK〗·a-1 year by year during the recent 44 years; the change of global sea surface wind speed is relatively gentle in the period of 1958 to 1975 and relatively sharp in the period of 1975 to 1983 The peak and valley of the annual mean global sea surface wind speed appeared in 1999 and 1975, respectively. (2) The change trends of global sea surface wind speed showed significant regional differences. The areas with an obvious increasing trend are mainly distributed in the Antarctic region, tropical Atlantic and North Pacific westerly zone waters, low latitudes in the Indian Ocean, and the regions near 60°S in the Southern Hemisphere, especially with the strongest increasing trend in the Southern Hemisphere high latitude waters; significantly decreasing areas are mainly distributed in the regions near the equatorial Middle East Pacific, Juan Fernandez Islands, the south westerly zone in the central Atlantic Ocean, as well as some sporadic waters. (3) The change trends of global sea surface wind speed showed significant seasonal differences with a significant linear increasing trend for all months. The sharpest increasing trend is in December (00103 m〖DK〗·s-1〖DK〗·a-1), and the gentlest increasing trend is in July (approximately 00033 m〖DK〗·s-1〖DK〗·a-1). (4) There is obvious periodic change in Global ocean sea surface wind speed with the periods being 22 to 43 years, as well as 65 years.
2014, 42(1):110-117.
Abstract:
Using the monthly precipitation data of 39 meteorological stations from 1961 to 2010 in rainy season over Tibetan Plateau and the NCAR/NCEP reanalysis data, the flood and drought distributions are discussed based on the 〖WTBX〗Z〖WTBZ〗 index and regional flood/drought indexes. The composite analysis method is used to analyze water vapor transport differences between flood and drought years over the Tibetan Plateau. The results show that droughts occur much more frequently than floods over the Tibetan Plateau in recent 50 years. The dry and wet conditions have obvious inter decadal variations. Floods and droughts over the Tibetan Plateau are closely linked to water vapor transport anomalies. There are significant differences between typical drought and flood years in the zonal, meridional, and the total water vapor fluxes and water vapor flux divergence over North Indian Ocean, the western North Pacific, and the mid latitude regions of Asian. The difference appears most significantly at the cross equatorial jet area; and the major difference in the zonal water vapor flux is found in the Somali jet area, and that in the meridional water vapor flux is found in in the Philippines jet area.
Using the monthly precipitation data of 39 meteorological stations from 1961 to 2010 in rainy season over Tibetan Plateau and the NCAR/NCEP reanalysis data, the flood and drought distributions are discussed based on the 〖WTBX〗Z〖WTBZ〗 index and regional flood/drought indexes. The composite analysis method is used to analyze water vapor transport differences between flood and drought years over the Tibetan Plateau. The results show that droughts occur much more frequently than floods over the Tibetan Plateau in recent 50 years. The dry and wet conditions have obvious inter decadal variations. Floods and droughts over the Tibetan Plateau are closely linked to water vapor transport anomalies. There are significant differences between typical drought and flood years in the zonal, meridional, and the total water vapor fluxes and water vapor flux divergence over North Indian Ocean, the western North Pacific, and the mid latitude regions of Asian. The difference appears most significantly at the cross equatorial jet area; and the major difference in the zonal water vapor flux is found in the Somali jet area, and that in the meridional water vapor flux is found in in the Philippines jet area.
2014, 42(1):118-124.
Abstract:
By utilizing the ADTD lightning observations, SWAN radar mosaics and CINRAD/SC Doppler radar data of Chengdu, an analysis is made of the characteristics of and relationship between CG (cloud to ground) lightning, strong precipitation and radar echoes of 100 cases in the 12 regional heavy rainfall events in 2009—2011. The results indicate that the frequency of negative flashes changes with time as precipitation intensity does, and there are single and multiple peaks. The higher the frequency of negative CG lighting is, the greater the likelihood of heavy precipitation occurrence is. During 83% of heavy rainfall events, about 6 to 30minutes before the persistent heavy rainfall, the frequencies of negative flashes increase suddenly and continuously, and during 56% of the events, there appears a peak of negative CG lightning. The sudden increasing of CG lightning frequency is a good indicator of heavy rainfall. During 67% of heavy rainfall events, about 6 to 30 minutes after the appearing of precipitation intensity peaks, there appears a peak of negative CG lightning. In the front of strong radar echoes, there occur weak negative flashes, mainly concentrated in the region above 35 dBz and moving along with radar echoes.
By utilizing the ADTD lightning observations, SWAN radar mosaics and CINRAD/SC Doppler radar data of Chengdu, an analysis is made of the characteristics of and relationship between CG (cloud to ground) lightning, strong precipitation and radar echoes of 100 cases in the 12 regional heavy rainfall events in 2009—2011. The results indicate that the frequency of negative flashes changes with time as precipitation intensity does, and there are single and multiple peaks. The higher the frequency of negative CG lighting is, the greater the likelihood of heavy precipitation occurrence is. During 83% of heavy rainfall events, about 6 to 30minutes before the persistent heavy rainfall, the frequencies of negative flashes increase suddenly and continuously, and during 56% of the events, there appears a peak of negative CG lightning. The sudden increasing of CG lightning frequency is a good indicator of heavy rainfall. During 67% of heavy rainfall events, about 6 to 30 minutes after the appearing of precipitation intensity peaks, there appears a peak of negative CG lightning. In the front of strong radar echoes, there occur weak negative flashes, mainly concentrated in the region above 35 dBz and moving along with radar echoes.
2014, 42(1):125-130.
Abstract:
MICAPS objective physical quantity data are used to analyze 82 strong convective weather causes from 2006 to 2011 in Lijiang. The main results indicate that before strong convection weather occurs, water vapor is mostly in the high or moderate humidity state, with thermal conditions mostly in a state of high temperature, high energy, and convective instability. The dynamic conditions are favorable to convective activities, such as negative vorticity at lower levels and positive vorticity at upper levels, and there was obvious cold advection, especially hails at the middle and upper levels.
MICAPS objective physical quantity data are used to analyze 82 strong convective weather causes from 2006 to 2011 in Lijiang. The main results indicate that before strong convection weather occurs, water vapor is mostly in the high or moderate humidity state, with thermal conditions mostly in a state of high temperature, high energy, and convective instability. The dynamic conditions are favorable to convective activities, such as negative vorticity at lower levels and positive vorticity at upper levels, and there was obvious cold advection, especially hails at the middle and upper levels.
2014, 42(1):131-139.
Abstract:
Based on the daily precipitation, weather phenomena, and snow depth of four meteorological stations in Dandong from October to the next April from 1955 to 2010, the climate change characteristics of snowfall in Dandong are studied. The results show that in the coastal area of the southern Dandong and the mountain area of the northern Dandong, there are obvious regional differences in beginning dates, ending dates, interval days, the annual number of days with snow, the annual amount of snowfall, precipitation phase state, daily maximum amount of snowfall, and daily maximum depth. Compared with the mountain area, the beginning date was later, and the ending date was earlier in coastal area; the number of days between beginning and ending dates was smaller, and annual number of snowfall days and annual amount of snowfall were less. Under the background of obviously increasing annual mean air temperature from October to next April from 1955 to 2010, the beginning date was delayed, and the ending date was advanced; the intervals were significantly shortened, and the annual numbers of snowfall days were reduced, especially the percentages of the mixed rain and snow days to snowfall days increased obviously; the amount of snowfall reduced, mainly pure snow, and the daily maximum amount of snowfall and the daily maximum depth decreased; the variation extent is different in the coastal area and the mountain area.
Based on the daily precipitation, weather phenomena, and snow depth of four meteorological stations in Dandong from October to the next April from 1955 to 2010, the climate change characteristics of snowfall in Dandong are studied. The results show that in the coastal area of the southern Dandong and the mountain area of the northern Dandong, there are obvious regional differences in beginning dates, ending dates, interval days, the annual number of days with snow, the annual amount of snowfall, precipitation phase state, daily maximum amount of snowfall, and daily maximum depth. Compared with the mountain area, the beginning date was later, and the ending date was earlier in coastal area; the number of days between beginning and ending dates was smaller, and annual number of snowfall days and annual amount of snowfall were less. Under the background of obviously increasing annual mean air temperature from October to next April from 1955 to 2010, the beginning date was delayed, and the ending date was advanced; the intervals were significantly shortened, and the annual numbers of snowfall days were reduced, especially the percentages of the mixed rain and snow days to snowfall days increased obviously; the amount of snowfall reduced, mainly pure snow, and the daily maximum amount of snowfall and the daily maximum depth decreased; the variation extent is different in the coastal area and the mountain area.
2014, 42(1):140-144.
Abstract:
An analysis is made of lightning flashes during three short duration severe rain events. The results show that: (1) The lightning flashes in three cases were mainly negative, and the ratio of negative lightning flashes to total lightning flashes is over 92%. (2) The lightning frequency peaks were one hour earlier in phase than precipitation peaks. (3) The 5 minute lightning frequency peaks were 5 to 60 minutes earlier than precipitation peaks. (4) The areas with negative lightning flashes concentrated are around the areas with the reflectivity of radar being above 40 dBz; the positive lightning flashes which occurred occasionally distributed in the weak echo areas; lightning flashes occurred mostly in the areas with the echo top being over 5 km and in the wind fields with radial velocity being uneven. The VIL had poor correlation with lightning flashes, and some lighting flashes occur in the areas where VIL is small. (5) Lightning characteristics differ for different clouds; some lightning frequency peaks occurred in the strong echo stage, but some occurred in the weak stage. Sometimes lightning flashes concentrated around or in the front of a strong echo area, which indicates the moving direction of the strong echoes. Some lightning flashes occurred in the developing or mature stage of clouds, and the negative lightning flashes were concentrated near a strong echo area. The lightning flashes were distributed dispersedly in the weakening stage of clouds, concentrated in the different sites.
An analysis is made of lightning flashes during three short duration severe rain events. The results show that: (1) The lightning flashes in three cases were mainly negative, and the ratio of negative lightning flashes to total lightning flashes is over 92%. (2) The lightning frequency peaks were one hour earlier in phase than precipitation peaks. (3) The 5 minute lightning frequency peaks were 5 to 60 minutes earlier than precipitation peaks. (4) The areas with negative lightning flashes concentrated are around the areas with the reflectivity of radar being above 40 dBz; the positive lightning flashes which occurred occasionally distributed in the weak echo areas; lightning flashes occurred mostly in the areas with the echo top being over 5 km and in the wind fields with radial velocity being uneven. The VIL had poor correlation with lightning flashes, and some lighting flashes occur in the areas where VIL is small. (5) Lightning characteristics differ for different clouds; some lightning frequency peaks occurred in the strong echo stage, but some occurred in the weak stage. Sometimes lightning flashes concentrated around or in the front of a strong echo area, which indicates the moving direction of the strong echoes. Some lightning flashes occurred in the developing or mature stage of clouds, and the negative lightning flashes were concentrated near a strong echo area. The lightning flashes were distributed dispersedly in the weakening stage of clouds, concentrated in the different sites.
2014, 42(1):145-150.
Abstract:
The T639L60 model data of 2010 are used as the forecast fields, and the NCEP data from 1980 to 2009 are used as the historical sample database. The analogue examples of T639L60 model forecast fields are picked out from the sample database, based on statistical forecast with dynamic analog, and the correction scheme of T639L60 model data is designed with the multiple regression method. The correction effectiveness of the scheme is tested using the T639L60 model data from January 2011 to June 2011 The results show that the correction effectiveness of the forecast fields over three days in China is obvious, based on statistical forecast with dynamic analog, and the correction effectiveness of synoptic situation fields is better than element fields.
The T639L60 model data of 2010 are used as the forecast fields, and the NCEP data from 1980 to 2009 are used as the historical sample database. The analogue examples of T639L60 model forecast fields are picked out from the sample database, based on statistical forecast with dynamic analog, and the correction scheme of T639L60 model data is designed with the multiple regression method. The correction effectiveness of the scheme is tested using the T639L60 model data from January 2011 to June 2011 The results show that the correction effectiveness of the forecast fields over three days in China is obvious, based on statistical forecast with dynamic analog, and the correction effectiveness of synoptic situation fields is better than element fields.
2014, 42(1):151-157.
Abstract:
In 21 and 22 May 2012, a heavy rainstorm process happened in Guizhou Province, which was a typical MCS triggered process, caused by the frontogenesis of type Ⅲ stationary front, under the guidance of a southern trough. The MCS was non linear with severe rainfall. Analysis reveals that the stationary front was strong; the frontogenesis process was obvious with a high energy tongue and a low vortex shear at the front, and a southerly jet on the south side. In the vertical direction, the front had a steep frontal area and strong upward motion, which was caused by the southern trough, the forward lean distribution, and the convective instability of the convex. These characteristics are beneficial to MCS: the high energy tongue and low vortex shear provide thermal and dynamic conditions for MCS, and the southerly jet is also an important factor. In the vertical direction, the convex area was important, and the distribution of θse and the forward lean distribution were beneficial. The moisture conditions in the front of and on the front were sufficient. Moisture convergence at the exit of the southerly jet and upward flow were sufficient to supply the moisture for MCS and the heavy rainstorm.
In 21 and 22 May 2012, a heavy rainstorm process happened in Guizhou Province, which was a typical MCS triggered process, caused by the frontogenesis of type Ⅲ stationary front, under the guidance of a southern trough. The MCS was non linear with severe rainfall. Analysis reveals that the stationary front was strong; the frontogenesis process was obvious with a high energy tongue and a low vortex shear at the front, and a southerly jet on the south side. In the vertical direction, the front had a steep frontal area and strong upward motion, which was caused by the southern trough, the forward lean distribution, and the convective instability of the convex. These characteristics are beneficial to MCS: the high energy tongue and low vortex shear provide thermal and dynamic conditions for MCS, and the southerly jet is also an important factor. In the vertical direction, the convex area was important, and the distribution of θse and the forward lean distribution were beneficial. The moisture conditions in the front of and on the front were sufficient. Moisture convergence at the exit of the southerly jet and upward flow were sufficient to supply the moisture for MCS and the heavy rainstorm.
2014, 42(1):158-163.
Abstract:
Based on the GPS/MET water vapor data, a comparative analysis of the GPS/MET vapor and four kinds radiosonde results calculated by using the regression method is conducted, and it is found that the radiosonde measurements of water vapor are generally 0.71 to 1.47 mm higher than those of GPS/MET, with the variance between 3.48 and 3.96, and the correlation coefficients are between 0.57 and 074. The variation amplitudes of RS92 radiosonde measurements of moisture are basically close to those of GPS/MET moisture，but the variation amplitudes of domestic sonde moisture measurements are obviously higher than those of GPS/MET by a factor of nearly 2.6 to 2.8. The microwave radiometer measurements of moisture are 16.12 mm higher than those of GPS/MET averagely. The analysis indicates that the measurements of microwave radiometers are obviously influenced by the revised models with different area corrections. Through the localization of the revised model, the abnormal high measurements of microwave radiometers are corrected, only 3 to 5 mm higher.
Based on the GPS/MET water vapor data, a comparative analysis of the GPS/MET vapor and four kinds radiosonde results calculated by using the regression method is conducted, and it is found that the radiosonde measurements of water vapor are generally 0.71 to 1.47 mm higher than those of GPS/MET, with the variance between 3.48 and 3.96, and the correlation coefficients are between 0.57 and 074. The variation amplitudes of RS92 radiosonde measurements of moisture are basically close to those of GPS/MET moisture，but the variation amplitudes of domestic sonde moisture measurements are obviously higher than those of GPS/MET by a factor of nearly 2.6 to 2.8. The microwave radiometer measurements of moisture are 16.12 mm higher than those of GPS/MET averagely. The analysis indicates that the measurements of microwave radiometers are obviously influenced by the revised models with different area corrections. Through the localization of the revised model, the abnormal high measurements of microwave radiometers are corrected, only 3 to 5 mm higher.
2014, 42(1):164-172.
Abstract:
In terms of the observations from the LS8000 lightning location system, Cloud to Ground (CG) lightning activities in Shanghai and its circumjacent regions are studied. The percentage of positive CG lightning in total CG lightning is about 85% and that of large current CG lightning (with the absolute value of current larger than 50 kA) is 56%. CG lightning activities highly centralized in the period from June to September, and peaked in August; for the temporal distribution of CG lightning, 13:00 to 21:00BT is an active periods, with peaks at 14:00BT and valleys in the morning. The monthly and hourly distributions of the percentage of the PCG (positive cloud to ground) lightning in total CG lightning present negative relationship to CG lightning. Setting 31°N as the boundary, the CG lightning density is generally 6 to 12 flushes/(km2〖DK〗·a) in the northern part of the analysis area and 24 to 48 flushes/(km2〖DK〗·a) in the southern part. At the same time, the CG lightning density on land is higher than those in lake and oceanic areas, while the percentage of PCG lightning and the large current CG lightning in the oceanic area is significantly higher than those on land. The time changes of spatial distribution of CG lightning show that CG lightning activities mainly appear on the land in afternoon and near the water in the morning, while in other periods presents the characters of transition, which is closely related to the heating effect of the underlying surface.
In terms of the observations from the LS8000 lightning location system, Cloud to Ground (CG) lightning activities in Shanghai and its circumjacent regions are studied. The percentage of positive CG lightning in total CG lightning is about 85% and that of large current CG lightning (with the absolute value of current larger than 50 kA) is 56%. CG lightning activities highly centralized in the period from June to September, and peaked in August; for the temporal distribution of CG lightning, 13:00 to 21:00BT is an active periods, with peaks at 14:00BT and valleys in the morning. The monthly and hourly distributions of the percentage of the PCG (positive cloud to ground) lightning in total CG lightning present negative relationship to CG lightning. Setting 31°N as the boundary, the CG lightning density is generally 6 to 12 flushes/(km2〖DK〗·a) in the northern part of the analysis area and 24 to 48 flushes/(km2〖DK〗·a) in the southern part. At the same time, the CG lightning density on land is higher than those in lake and oceanic areas, while the percentage of PCG lightning and the large current CG lightning in the oceanic area is significantly higher than those on land. The time changes of spatial distribution of CG lightning show that CG lightning activities mainly appear on the land in afternoon and near the water in the morning, while in other periods presents the characters of transition, which is closely related to the heating effect of the underlying surface.
27 Application of Hail Suppression Decision Making System in an Artificial Hail Suppression Operation
2014, 42(1):173-179.
Abstract:
The artificial hail suppression decision command system developed by the Dalian Weather Modification Office performed well in the practical operation in Dalian. A hail case on 7 June 2012 is used as an example, to introduce the functions and technical procedures of the system in real time hail suppression operation, including the system automatic identification of hail cloud initial echoes and types, and the quantitative output of operation alarm, decision making, and operation projects, as well as the real time operation commands, etc. Through system running and reasonable operation commanding, the hail cloud development was suppressed effectively, and the loss and waste of ammunition from blind operation were avoided. The system has been put into operation in Dalian presently.
The artificial hail suppression decision command system developed by the Dalian Weather Modification Office performed well in the practical operation in Dalian. A hail case on 7 June 2012 is used as an example, to introduce the functions and technical procedures of the system in real time hail suppression operation, including the system automatic identification of hail cloud initial echoes and types, and the quantitative output of operation alarm, decision making, and operation projects, as well as the real time operation commands, etc. Through system running and reasonable operation commanding, the hail cloud development was suppressed effectively, and the loss and waste of ammunition from blind operation were avoided. The system has been put into operation in Dalian presently.
2014, 42(1):180-186.
Abstract:
Based on the hourly data of the regional automatic weather stations in Ningbo, an analysis is made of the variability coefficients of sunshine duration, temperature, and humidity, as well as the relation between these meteorological elements and flowering periods. The results show that hour by hour accumulated temperatures (℃〖DK〗·h) indicate better relation compared with day by day accumulated temperature, and the predictors are obtained based on the extreme variability and correlation coefficients. The BP neural network method is applied to set up mid term flowering forecast models, and ECMWF fine grid model products are used as well. Trial forecasts perform quite well in forecasting blossom time and duration. The method can help improve meteorological service for agricultural activities.
Based on the hourly data of the regional automatic weather stations in Ningbo, an analysis is made of the variability coefficients of sunshine duration, temperature, and humidity, as well as the relation between these meteorological elements and flowering periods. The results show that hour by hour accumulated temperatures (℃〖DK〗·h) indicate better relation compared with day by day accumulated temperature, and the predictors are obtained based on the extreme variability and correlation coefficients. The BP neural network method is applied to set up mid term flowering forecast models, and ECMWF fine grid model products are used as well. Trial forecasts perform quite well in forecasting blossom time and duration. The method can help improve meteorological service for agricultural activities.
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.