Volume 39,Issue 6,2011 Table of Contents
2011, 39(6):673-677.
Abstract:
A meteorological numerical simulation system for urban emergency service is established， according to the needs of urban emergency responses. There are two main models included in the system： Pollution Diffusion Rapid Numerical Prediction Model （PDRNPM）， which is mainly based on MM5 and RAMS 6.0， and Rapid Emergency Meteorological Service Software （REMSS）， which is based on the urban subdomain model and the Gauss model. PDRNPM is better for its precision and predictability， allowing the emergency staff to predict the gas diffusion situation of one hour later within 15 minutes. REMSS is easy to install， operate and give responses quickly， and can simulate gas diffusion within 2 to 3 minutes once emergency situation is triggered. Applied in the Beijing Olympics Games 2008 and Paralympics Games 2008 and routine emergency exercise of Beijing， it is proved that the system can well meet the demands of emergency command due to its time effectiveness and applicalibility and can provide reliable realtime references for the Beijing Emergency Commode Center.
A meteorological numerical simulation system for urban emergency service is established， according to the needs of urban emergency responses. There are two main models included in the system： Pollution Diffusion Rapid Numerical Prediction Model （PDRNPM）， which is mainly based on MM5 and RAMS 6.0， and Rapid Emergency Meteorological Service Software （REMSS）， which is based on the urban subdomain model and the Gauss model. PDRNPM is better for its precision and predictability， allowing the emergency staff to predict the gas diffusion situation of one hour later within 15 minutes. REMSS is easy to install， operate and give responses quickly， and can simulate gas diffusion within 2 to 3 minutes once emergency situation is triggered. Applied in the Beijing Olympics Games 2008 and Paralympics Games 2008 and routine emergency exercise of Beijing， it is proved that the system can well meet the demands of emergency command due to its time effectiveness and applicalibility and can provide reliable realtime references for the Beijing Emergency Commode Center.
2011, 39(6):678-684.
Abstract:
Based on the intensive automatic weather station and radar wind profiler data with high temporal and spatial resolution， the mesoscale observational characteristics of three shortduration rainstorm processes in Xingtai city are analyzed. The shortduration rainstorm was produced under the favorable largescale circulation background. The lower layer shear system， strong vertical wind shear between middle and low levels， surface low pressure and inverse trough were the favorable conditions for convergence and ascending motion. The warm wet air flow from southwest interacted with the cold air from the westerly winds and northeast backflow. The surface mesoscale shear was the trigger system， whose position was consistent with the intensive precipitation area. The intensive precipitation corresponded to the beginning， duration， and strength of east winds in the boundary layer. The surface ascending eastwinds were forced by the convergences resulted from the topographic forcing， and so the mesoscale convergence system was strengthened. The urban atmospheric thermal forcing and topographic effect triggered jointly the urban shortduration rainstorms.
Based on the intensive automatic weather station and radar wind profiler data with high temporal and spatial resolution， the mesoscale observational characteristics of three shortduration rainstorm processes in Xingtai city are analyzed. The shortduration rainstorm was produced under the favorable largescale circulation background. The lower layer shear system， strong vertical wind shear between middle and low levels， surface low pressure and inverse trough were the favorable conditions for convergence and ascending motion. The warm wet air flow from southwest interacted with the cold air from the westerly winds and northeast backflow. The surface mesoscale shear was the trigger system， whose position was consistent with the intensive precipitation area. The intensive precipitation corresponded to the beginning， duration， and strength of east winds in the boundary layer. The surface ascending eastwinds were forced by the convergences resulted from the topographic forcing， and so the mesoscale convergence system was strengthened. The urban atmospheric thermal forcing and topographic effect triggered jointly the urban shortduration rainstorms.
2011, 39(6):685-691.
Abstract:
The finemode aerosol concentration and the size distributions from the ground to 7 km over Beijing in 2004 are analyzed， by means of the data within and above the planetary boundary layer from the optical spectrometer probes mounted on a light aircraft. The results show that aerosol particles over the Beijing area had a uniform distribution below the mixed layer， decreased with height significantly between 1 to 2 km， and decreased slowly with height above 2 km. At higher levels， the number concentration of aerosols was smaller than 200 cm-3 with less variation. When there existed inversion， finemode aerosols often formed in the“accumulation layer”near the top of the boundary layer. Under highpressure conditions， the number concentration of aerosols near the ground was about 500 to 800 cm-3; while in a weak lowpressure case， the number concentration of aerosols near the ground was about 8000/cm3.The observed finemode aerosol size distributions show a singlepeaked mode.
The finemode aerosol concentration and the size distributions from the ground to 7 km over Beijing in 2004 are analyzed， by means of the data within and above the planetary boundary layer from the optical spectrometer probes mounted on a light aircraft. The results show that aerosol particles over the Beijing area had a uniform distribution below the mixed layer， decreased with height significantly between 1 to 2 km， and decreased slowly with height above 2 km. At higher levels， the number concentration of aerosols was smaller than 200 cm-3 with less variation. When there existed inversion， finemode aerosols often formed in the“accumulation layer”near the top of the boundary layer. Under highpressure conditions， the number concentration of aerosols near the ground was about 500 to 800 cm-3; while in a weak lowpressure case， the number concentration of aerosols near the ground was about 8000/cm3.The observed finemode aerosol size distributions show a singlepeaked mode.
2011, 39(6):692-696.
Abstract:
The urban heat island changes in Chuxiong and Dali， two cities on the Yunnan plateau， are studied and compared with the data of air temperature， precipitation， relative humidity， average wind speed and so on from 1971 to 2000. The grey correlation degree is used to explain the causes of changes. The results indicate that the intensity of urban heat island is increasing gradually in Chuxiong in recent thirty years， while the increase in the Dali is less obvious; the monthly changes of urban heat island intensity in the two cities are basically the same: strong in dry season，weak in rainy season； the heat island intensity is strong in the daytime and weak at night in Chuxiong，but strong in the early morning and weak in the early evening in Dali.
The urban heat island changes in Chuxiong and Dali， two cities on the Yunnan plateau， are studied and compared with the data of air temperature， precipitation， relative humidity， average wind speed and so on from 1971 to 2000. The grey correlation degree is used to explain the causes of changes. The results indicate that the intensity of urban heat island is increasing gradually in Chuxiong in recent thirty years， while the increase in the Dali is less obvious; the monthly changes of urban heat island intensity in the two cities are basically the same: strong in dry season，weak in rainy season； the heat island intensity is strong in the daytime and weak at night in Chuxiong，but strong in the early morning and weak in the early evening in Dali.
2011, 39(6):697-702.
Abstract:
The cloud and precipitation resources, weather systems propitious to precipitation enhancement operations, precipitation echo characteristics, and indexes of precipitation enhancement operations in Northwest Fujian are analyzed, based on the CINRAD radar echo images, 850 hPa synoptic charts and surface precipitation data from 299 weather processes from May 2005 to July 2007. The results show that the chief weather systems propitious to precipitation enhancement operations include continental high, subtropical anticyclone, warmsector convergence, tropical convergence, the other, trough, typhoon (low pressure), low vortex, and low vortex shear, respectively. Stratuscumulus mixed clouds were the primary objects of local precipitation enhancement operation. For cumuliform clouds and stratuscumulus mixed clouds, the larger the echo height and area were, the higher the corresponding precipitation grade was. The echo intensity and the depth of negative temperature layer of stratuscumulus mixed clouds had great effects on precipitation grade. The indexes of rocket precipitation enhancement operations in Northwest Fujian were: the echo intensity of cumuliform clouds and stratuscumulus mixed clouds should be larger than 30 and 25 dBz, the echo top should be higher than 5500 and 5000 meters, the depth of negative temperature layer should be larger than 1500 and 2000 meters, the echo area should be larger than 1000 and 2500 square kilometers, the vertically integrated liquid water should be more than 1 kg〖DK〗·m-2 , and the cloud top temperature of nephsystem should range from -28 ℃ to -12 ℃, respectively.
The cloud and precipitation resources, weather systems propitious to precipitation enhancement operations, precipitation echo characteristics, and indexes of precipitation enhancement operations in Northwest Fujian are analyzed, based on the CINRAD radar echo images, 850 hPa synoptic charts and surface precipitation data from 299 weather processes from May 2005 to July 2007. The results show that the chief weather systems propitious to precipitation enhancement operations include continental high, subtropical anticyclone, warmsector convergence, tropical convergence, the other, trough, typhoon (low pressure), low vortex, and low vortex shear, respectively. Stratuscumulus mixed clouds were the primary objects of local precipitation enhancement operation. For cumuliform clouds and stratuscumulus mixed clouds, the larger the echo height and area were, the higher the corresponding precipitation grade was. The echo intensity and the depth of negative temperature layer of stratuscumulus mixed clouds had great effects on precipitation grade. The indexes of rocket precipitation enhancement operations in Northwest Fujian were: the echo intensity of cumuliform clouds and stratuscumulus mixed clouds should be larger than 30 and 25 dBz, the echo top should be higher than 5500 and 5000 meters, the depth of negative temperature layer should be larger than 1500 and 2000 meters, the echo area should be larger than 1000 and 2500 square kilometers, the vertically integrated liquid water should be more than 1 kg〖DK〗·m-2 , and the cloud top temperature of nephsystem should range from -28 ℃ to -12 ℃, respectively.
2011, 39(6):703-708.
Abstract:
The Doppler weather radar parameters of seeding and nonseeding clouds， such as echo top， reflectivity， vertically integrated liquid， echo area， etc.， are analyzed before and after weather modification operations by using the Doppler radar detection data and smallscale and mesoscale ground precipitation data. The results show that all the values of the Doppler echo parameters for the target clouds increased after seeding， reaching the maximum in 20 or 30 min, while the enlargement rate of the contrast cloud is smaller than that of the target cloud. The precipitation downwind reaches the maximum in 20 or 30 min， which is corresponding to the changes of radar parameters of the target cloud. While the rainfall intensity and precipitation of the contrast clouds are less than those of the target clouds.
The Doppler weather radar parameters of seeding and nonseeding clouds， such as echo top， reflectivity， vertically integrated liquid， echo area， etc.， are analyzed before and after weather modification operations by using the Doppler radar detection data and smallscale and mesoscale ground precipitation data. The results show that all the values of the Doppler echo parameters for the target clouds increased after seeding， reaching the maximum in 20 or 30 min, while the enlargement rate of the contrast cloud is smaller than that of the target cloud. The precipitation downwind reaches the maximum in 20 or 30 min， which is corresponding to the changes of radar parameters of the target cloud. While the rainfall intensity and precipitation of the contrast clouds are less than those of the target clouds.
2011, 39(6):709-713.
Abstract:
Ground lightning flash density Ng is one of most important parameters in lightning risk assessment. The conventional method of lightning risk assessment is to adopt the observed annualmean number of thunder days (Td) from local meteorological stations to calculate Ng and consider it a constant for one city or even a certain area, which is of certain limitations as the distribution of lightning is depended on the topographical, geological, edaphic, meteorological, and environmental features. Based on the conception of Ng, the processed data from the calibrated lightning location system and the calculated Td by Kriging interpolation, a corresponding program is developed by the C# language to obtain more reliable values of Ng in a more convenient way for the use of lightning risk assessment.
Ground lightning flash density Ng is one of most important parameters in lightning risk assessment. The conventional method of lightning risk assessment is to adopt the observed annualmean number of thunder days (Td) from local meteorological stations to calculate Ng and consider it a constant for one city or even a certain area, which is of certain limitations as the distribution of lightning is depended on the topographical, geological, edaphic, meteorological, and environmental features. Based on the conception of Ng, the processed data from the calibrated lightning location system and the calculated Td by Kriging interpolation, a corresponding program is developed by the C# language to obtain more reliable values of Ng in a more convenient way for the use of lightning risk assessment.
2011, 39(6):714-718.
Abstract:
Based on the lightning disasters from 2007 to 2009， making use of MICAPS data， an analysis is made of nine lightning disasters occurred in the three years. The results indicate that all lightning disasters were produced under the background of a largescale deep low system. In seven of the lightning events， there was a trumpetshaped pattern on the 〖WTBX〗T〖WTBZ〗ln〖WTBX〗p〖WTBZ〗 chart or inversion temperature pattern or lower SI （less than 2）， and the physical elements， as vertical ascending velocity， is consistent with the 〖WTBX〗T〖WTBZ〗ln〖WTBX〗p〖WTBZ〗 chart or SI. The other two lightning disasters occurred under the background of severe rainfall in stable weather situation. The probability of inducing disasters for lightning is higher in the low humidity months.
Based on the lightning disasters from 2007 to 2009， making use of MICAPS data， an analysis is made of nine lightning disasters occurred in the three years. The results indicate that all lightning disasters were produced under the background of a largescale deep low system. In seven of the lightning events， there was a trumpetshaped pattern on the 〖WTBX〗T〖WTBZ〗ln〖WTBX〗p〖WTBZ〗 chart or inversion temperature pattern or lower SI （less than 2）， and the physical elements， as vertical ascending velocity， is consistent with the 〖WTBX〗T〖WTBZ〗ln〖WTBX〗p〖WTBZ〗 chart or SI. The other two lightning disasters occurred under the background of severe rainfall in stable weather situation. The probability of inducing disasters for lightning is higher in the low humidity months.
2011, 39(6):719-722.
Abstract:
Based on numerical forecast products （MM5）， a fog forecast model is established with the statistical method for highways and the nearby 460 weather stations in North China. The results of the verification for more than 2 years show that CSI （Critical Success Index） for visibility being less than 5 km for 24 hours forecast is 0.61 at Beijing and 0.68 at 7 stations along the JingJinTang highway， respectively.The mean fogornot forecast accuracy rates are both 0.81. Two events of low visibility weather in 2007 are discussed and forecasted successfully， which indicates the method is applicable for fog forecasting.
Based on numerical forecast products （MM5）， a fog forecast model is established with the statistical method for highways and the nearby 460 weather stations in North China. The results of the verification for more than 2 years show that CSI （Critical Success Index） for visibility being less than 5 km for 24 hours forecast is 0.61 at Beijing and 0.68 at 7 stations along the JingJinTang highway， respectively.The mean fogornot forecast accuracy rates are both 0.81. Two events of low visibility weather in 2007 are discussed and forecasted successfully， which indicates the method is applicable for fog forecasting.
2011, 39(6):723-730.
Abstract:
Through checking missing data， climate limits， historical extreme values， time and space consistency， trend curve， etc.， an analysis is made of the quality of automatic weather stations data (including visibility， humidity， temperature， surface temperature， and wind) from the Huabei expressway in Tianjin It is found out that the main problem for the automatic weather stations on expressways is data missing， too small variability or constant data within a certain time (generated by equipment failures) In rare cases， there exist error data outside the climate limits By means of the trend analysis method，suspicious data are analyzed by checking the history values， time consistency， etc.， and the results indicate that the error rate of suspicious data is generally acceptable， and the currently used thresholds need to be improved continuously
Through checking missing data， climate limits， historical extreme values， time and space consistency， trend curve， etc.， an analysis is made of the quality of automatic weather stations data (including visibility， humidity， temperature， surface temperature， and wind) from the Huabei expressway in Tianjin It is found out that the main problem for the automatic weather stations on expressways is data missing， too small variability or constant data within a certain time (generated by equipment failures) In rare cases， there exist error data outside the climate limits By means of the trend analysis method，suspicious data are analyzed by checking the history values， time consistency， etc.， and the results indicate that the error rate of suspicious data is generally acceptable， and the currently used thresholds need to be improved continuously
2011, 39(6):731-735.
Abstract:
Using the ultraviolet ray monitoring data from 2006 to 2008 in Shijiazhuang， the characteristics of the ultraviolet radiation in the past three years are analyzed. The results show that the UV levels of Shijiazhuang ranged from Level 1 to Level 4， corresponding to 175， 251， 220， and 432 for the number of days， respectively. The relatively high level occurred most frequently， and the moderate level and higher accounted for 60.3%， which means that Shijiazhuang is an area with relatively highlevel ultraviolet radiation. The ultraviolet radiation was the strongest in spring and summer and the weakest in winter. The diurnal cycle of the ultraviolet radiation was very obvious， with a singlepeak distribution. The main meteorological factors that affect ultraviolet radiation are determined through correlation analysis. The ultraviolet index forecast equation containing a number of weather factors is established by using the multiple regression method. The accuracy rate of the equations for various seasons was above 50%， with the best accuracy rate being over 70% for autumn and winter. The equations could be used in operational ultraviolet index forecasting.
Using the ultraviolet ray monitoring data from 2006 to 2008 in Shijiazhuang， the characteristics of the ultraviolet radiation in the past three years are analyzed. The results show that the UV levels of Shijiazhuang ranged from Level 1 to Level 4， corresponding to 175， 251， 220， and 432 for the number of days， respectively. The relatively high level occurred most frequently， and the moderate level and higher accounted for 60.3%， which means that Shijiazhuang is an area with relatively highlevel ultraviolet radiation. The ultraviolet radiation was the strongest in spring and summer and the weakest in winter. The diurnal cycle of the ultraviolet radiation was very obvious， with a singlepeak distribution. The main meteorological factors that affect ultraviolet radiation are determined through correlation analysis. The ultraviolet index forecast equation containing a number of weather factors is established by using the multiple regression method. The accuracy rate of the equations for various seasons was above 50%， with the best accuracy rate being over 70% for autumn and winter. The equations could be used in operational ultraviolet index forecasting.
2011, 39(6):736-740.
Abstract:
Using the annual daily temperature data from 1961 to 2008， the changes of meteorological conditions and energysaving potentials during heating periods in Gangcha County of Qinghai Province are analyzed by the mathematicalstatistical method. The results indicate that the mean temperature in the heating period rose gradually while the negative accumulated temperature of the same period decreased from 1961 to 2008. As a result， the starting date of heating season postponed， but the ending date advanced， and the heating length remarkably shortened. The HDD （Heating Degree Day） was closely related to the average temperature of the heating period， decreased significantly， especially after the abrupt temperature change in 1994， which led to less cold winters and made the energy demand declined remarkably. The extraordinary high requirements for hearting energy resources were mainly in the 1960s; higherthannormal requirements were mainly between the 1970s and 1980s; lowerthannormal requirements were found after the middle 1980s， mainly occurred after 2000. From a meteorological point of view， about 7% of annual heating consumption can be saved owing to climate warming， which is beneficial for energy conservation and air pollution control.
Using the annual daily temperature data from 1961 to 2008， the changes of meteorological conditions and energysaving potentials during heating periods in Gangcha County of Qinghai Province are analyzed by the mathematicalstatistical method. The results indicate that the mean temperature in the heating period rose gradually while the negative accumulated temperature of the same period decreased from 1961 to 2008. As a result， the starting date of heating season postponed， but the ending date advanced， and the heating length remarkably shortened. The HDD （Heating Degree Day） was closely related to the average temperature of the heating period， decreased significantly， especially after the abrupt temperature change in 1994， which led to less cold winters and made the energy demand declined remarkably. The extraordinary high requirements for hearting energy resources were mainly in the 1960s; higherthannormal requirements were mainly between the 1970s and 1980s; lowerthannormal requirements were found after the middle 1980s， mainly occurred after 2000. From a meteorological point of view， about 7% of annual heating consumption can be saved owing to climate warming， which is beneficial for energy conservation and air pollution control.
2011, 39(6):741-744.
Abstract:
By use of average wind speed and direction data from 1957 to 2007 and the 10minute 24h wind speed measurements from the surface automatic meteorological station of Alashankou from 1 February 2007 to 31 December 2008, it is concluded with the statistical method that the number of hours of effective wind energy is 4575, and the effective wind energy density is 166 W/m2. The effective wind energy is much greater in Spring, Summer and Autumn than that in Winter in this area. Alashankou is a wind energy rich, but seasonally available area, has big potentials in the utilization of energy resources. The Alashankou port is an important hub and platform for the western China, which has an increasing energy need. The utilization of wind energy in this area has great significance for environment protection and economic development.
By use of average wind speed and direction data from 1957 to 2007 and the 10minute 24h wind speed measurements from the surface automatic meteorological station of Alashankou from 1 February 2007 to 31 December 2008, it is concluded with the statistical method that the number of hours of effective wind energy is 4575, and the effective wind energy density is 166 W/m2. The effective wind energy is much greater in Spring, Summer and Autumn than that in Winter in this area. Alashankou is a wind energy rich, but seasonally available area, has big potentials in the utilization of energy resources. The Alashankou port is an important hub and platform for the western China, which has an increasing energy need. The utilization of wind energy in this area has great significance for environment protection and economic development.
2011, 39(6):745-752.
Abstract:
The methods used in the studies of medical meteorology within its developing history are reviewed and classified into three categories: statistic methods， such as the corelational analysis， regression analysis， timeseries analysis; epidemiological methods， such as descriptive studies， cohort studies， casecontrol studies， and experimental epidemiology; toxicological methods， such as animal experiments and cellularmolecular experiments. Besides， the perspectives of these methods are also explored， and some issues that should be paid attention in the future study of Medical Meteorology are discussed. The research results in this field can be useful in the medical meteorological forecasting services.
The methods used in the studies of medical meteorology within its developing history are reviewed and classified into three categories: statistic methods， such as the corelational analysis， regression analysis， timeseries analysis; epidemiological methods， such as descriptive studies， cohort studies， casecontrol studies， and experimental epidemiology; toxicological methods， such as animal experiments and cellularmolecular experiments. Besides， the perspectives of these methods are also explored， and some issues that should be paid attention in the future study of Medical Meteorology are discussed. The research results in this field can be useful in the medical meteorological forecasting services.
2011, 39(6):753-760.
Abstract:
The progresses in the studies in the recent years of NAM/AO （Northern Hemisphere Anuular Mode / Arctic Oscillation) are reviewed, with the emphases on the influences of the NAM/AO on weather and climate, the physical mechanisms of NAM/AO，the waveflow interaction theory, and the baroclinic Rossby wave and quasistationary planetary wave activities on the NAM/AO’s three regional activity centers. During recent years, many studies show that tropospheric fluctuations of NAM/AO are associated with baroclinic waves, while fluctuations are associated with the quasistationary planetary waves in the stratosphere. It is found that the regions where baroclinic wave activities are frequent are the Pacific and Atlantic in the Northern Hemisphere, and the peak value areas are manifested as storm tracks. Besides, the wave breaking is the trigger of NAM/AO events in North Atlantic. On the other hand, the stratospheric zonal winds modify the upwardpropagation of the troposphereoriginated planetary waves, and then these waves refract, reflect and break, which thereby create fluctuations in the strength of the polar vortex in winter. The planetary waves link the NAM/AO’s three regional activity centers: the horizontal propagation and dispersion of quasistationary waves are crucial for the Pacific storm tracks, and the latitudinal position of the Pacific storm track plays an important role for determining the phase of NAO; the propagation of quasistationary planetary waves into the stratosphere over high latitudes can alter the intensity of the polar vortex.
The progresses in the studies in the recent years of NAM/AO （Northern Hemisphere Anuular Mode / Arctic Oscillation) are reviewed, with the emphases on the influences of the NAM/AO on weather and climate, the physical mechanisms of NAM/AO，the waveflow interaction theory, and the baroclinic Rossby wave and quasistationary planetary wave activities on the NAM/AO’s three regional activity centers. During recent years, many studies show that tropospheric fluctuations of NAM/AO are associated with baroclinic waves, while fluctuations are associated with the quasistationary planetary waves in the stratosphere. It is found that the regions where baroclinic wave activities are frequent are the Pacific and Atlantic in the Northern Hemisphere, and the peak value areas are manifested as storm tracks. Besides, the wave breaking is the trigger of NAM/AO events in North Atlantic. On the other hand, the stratospheric zonal winds modify the upwardpropagation of the troposphereoriginated planetary waves, and then these waves refract, reflect and break, which thereby create fluctuations in the strength of the polar vortex in winter. The planetary waves link the NAM/AO’s three regional activity centers: the horizontal propagation and dispersion of quasistationary waves are crucial for the Pacific storm tracks, and the latitudinal position of the Pacific storm track plays an important role for determining the phase of NAO; the propagation of quasistationary planetary waves into the stratosphere over high latitudes can alter the intensity of the polar vortex.
2011, 39(6):761-767.
Abstract:
Based on the monthly 600 hPa ECMWF reanalysis data， the trajectories and characteristics of the lowlevel low pressure systems in active and weak monsoon years are analyzed， respectively. The results show that the low pressure system formed in April in the southwest of Qinghai Province and moved into Xizang along the southwest direction in May and then shifted westward with longitudinal fluctuations. After it reached the “farthermost west point，” it shifted back with attenuation and dissipated in October. The center intensities of the low pressure system in monsoon active years were stronger than those in monsoon weak years. The trajectories of the low pressure system were farther north than normal in active monsoon years and farther south with a Vshaped distribution in weak monsoon years with longitudinal fluctuations. The low pressure systems often formed repeatedly in monsoon weak years at the early stage. The low pressure systems over India formed later and more southslanting in active monsoon years than in weak monsoon years at the maturity stage. The high pressure system in the northwest of the low pressure system weakened at the later stage. In October， the eastern extension of the subtropical high ridge was farther east in weak monsoon years than in active monsoon years.
Based on the monthly 600 hPa ECMWF reanalysis data， the trajectories and characteristics of the lowlevel low pressure systems in active and weak monsoon years are analyzed， respectively. The results show that the low pressure system formed in April in the southwest of Qinghai Province and moved into Xizang along the southwest direction in May and then shifted westward with longitudinal fluctuations. After it reached the “farthermost west point，” it shifted back with attenuation and dissipated in October. The center intensities of the low pressure system in monsoon active years were stronger than those in monsoon weak years. The trajectories of the low pressure system were farther north than normal in active monsoon years and farther south with a Vshaped distribution in weak monsoon years with longitudinal fluctuations. The low pressure systems often formed repeatedly in monsoon weak years at the early stage. The low pressure systems over India formed later and more southslanting in active monsoon years than in weak monsoon years at the maturity stage. The high pressure system in the northwest of the low pressure system weakened at the later stage. In October， the eastern extension of the subtropical high ridge was farther east in weak monsoon years than in active monsoon years.
17 Observational Characteristics of Gravity Waves in Lower Stratosphere over a Tibetan Plateau Station
2011, 39(6):768-771.
Abstract:
Using the high vertical resolution radiosonde data of May 2008 at the Hongyuan meteorological station located in the Tibetan Plateau, the observational characteristics of gravity waves in the lower stratosphere (19 to 26 km) are investigated. The results show that the dominant vertical wavelengths of the gravity waves are 2 to 4 km, with a mean value of 2.9 km; the dominant horizontal wavelengths are 100 to 600 km, with an average value of 311 km; the intrinsic frequency is dominated by 1.5f to 3.5f (Coriolis parameter), with a medium value of 2.5f, corresponding to an intrinsic period of 9 hours. The dominant (85%) wave energy propagation direction is upward; the horizontal propagation direction is mainly eastward. The dominant vertical intrinsic phase velocities range from -0.2 to 0.05 m/s, with an average value of -0.12 m/s; the dominant horizontal intrinsic phase velocities range from 5 to 15 m/s, with a mean value of 11.3 m/s.
Using the high vertical resolution radiosonde data of May 2008 at the Hongyuan meteorological station located in the Tibetan Plateau, the observational characteristics of gravity waves in the lower stratosphere (19 to 26 km) are investigated. The results show that the dominant vertical wavelengths of the gravity waves are 2 to 4 km, with a mean value of 2.9 km; the dominant horizontal wavelengths are 100 to 600 km, with an average value of 311 km; the intrinsic frequency is dominated by 1.5f to 3.5f (Coriolis parameter), with a medium value of 2.5f, corresponding to an intrinsic period of 9 hours. The dominant (85%) wave energy propagation direction is upward; the horizontal propagation direction is mainly eastward. The dominant vertical intrinsic phase velocities range from -0.2 to 0.05 m/s, with an average value of -0.12 m/s; the dominant horizontal intrinsic phase velocities range from 5 to 15 m/s, with a mean value of 11.3 m/s.
2011, 39(6):772-778.
Abstract:
The precipitation variation over Southeast China during recent 50 years and its relationship with SST are analyzed by using the SVD (Singular Value Decomposition) method. The results show that the India Ocean, South China Sea and the eastern Pacific Ocean were key regions for influencing the precipitation over Southeast China. The autumn and winter precipitations over Southeast China were not strongly affected by the SST of previous months as a whole, while there is marked negative relationship between the summer precipitation and the previous summer SST, especially in North India and the South China Sea.
The precipitation variation over Southeast China during recent 50 years and its relationship with SST are analyzed by using the SVD (Singular Value Decomposition) method. The results show that the India Ocean, South China Sea and the eastern Pacific Ocean were key regions for influencing the precipitation over Southeast China. The autumn and winter precipitations over Southeast China were not strongly affected by the SST of previous months as a whole, while there is marked negative relationship between the summer precipitation and the previous summer SST, especially in North India and the South China Sea.
2011, 39(6):779-784.
Abstract:
Nowcasting of severe convective weather in the northcentral region of Ningxia within 0 to 1 hour based on radar tracking and extrapolation is realized by using the Yinchuan Doppler Weather Radar data, by means of the TREC algorithm with the localized quality control of radar data. The webbased Ningxia nowcasting system is established on the basis of Google Maps with highresolution geographic information. This system can display multisource meteorological data, such as data of radar, satellites, lightning position finders, etc.， as well as various derived and forecasted products. It can also provide forecasters with technical support according to the distributional characteristics of terrain conditions, population, industry and agriculture.
Nowcasting of severe convective weather in the northcentral region of Ningxia within 0 to 1 hour based on radar tracking and extrapolation is realized by using the Yinchuan Doppler Weather Radar data, by means of the TREC algorithm with the localized quality control of radar data. The webbased Ningxia nowcasting system is established on the basis of Google Maps with highresolution geographic information. This system can display multisource meteorological data, such as data of radar, satellites, lightning position finders, etc.， as well as various derived and forecasted products. It can also provide forecasters with technical support according to the distributional characteristics of terrain conditions, population, industry and agriculture.
2011, 39(6):785-790.
Abstract:
Based on the conventional observation and radiosonde data at 850 hPa and 500 hPa from 1990 to 2008， the spatial and temporal features of hailing days and atmospheric circulation patterns over Fujian are analyzed. The results show that hail disasters occurred frequently in Northwest Fujian， and there were a decreasing trend in recent years. The monthly change of hail events presents a typical multiplepeak pattern with the big peak in April and two small peaks in July and November. Hails occurred mainly from 14:00 to 20:00. The hail events usually occurred solitarily， and the affected stations were less than three. From November to next May， the main circulation patterns at 850 hPa favorable for hail generation include “moderate warm shear，” “moderate vortex and cold shear，” “moderate cold shear，” and “eastward deflection trough.” The hailfalling probabilities in the pattern of “westslanting cold shear” and “northwardslanting warm shear” were smaller than those in “moderate vortex and shear，” and greater than that in “southslanting shear.” The 74.1% of hail days were associated with a strong lowlevel southwest jet， mostly “moderate jet” or “northslanting jet.” The main weather patterns affected three or more were “moderate warm shear，” “moderate vortex and cold shear.” The 81.5% of hail events were associated with the strong lowlevel southwest jet. From June to September， the circulation patterns at 500hPa favorable for hails were “peripheraltype subtropical high” and “small subtropical high，”and the probability of largescale hail weather was small.
Based on the conventional observation and radiosonde data at 850 hPa and 500 hPa from 1990 to 2008， the spatial and temporal features of hailing days and atmospheric circulation patterns over Fujian are analyzed. The results show that hail disasters occurred frequently in Northwest Fujian， and there were a decreasing trend in recent years. The monthly change of hail events presents a typical multiplepeak pattern with the big peak in April and two small peaks in July and November. Hails occurred mainly from 14:00 to 20:00. The hail events usually occurred solitarily， and the affected stations were less than three. From November to next May， the main circulation patterns at 850 hPa favorable for hail generation include “moderate warm shear，” “moderate vortex and cold shear，” “moderate cold shear，” and “eastward deflection trough.” The hailfalling probabilities in the pattern of “westslanting cold shear” and “northwardslanting warm shear” were smaller than those in “moderate vortex and shear，” and greater than that in “southslanting shear.” The 74.1% of hail days were associated with a strong lowlevel southwest jet， mostly “moderate jet” or “northslanting jet.” The main weather patterns affected three or more were “moderate warm shear，” “moderate vortex and cold shear.” The 81.5% of hail events were associated with the strong lowlevel southwest jet. From June to September， the circulation patterns at 500hPa favorable for hails were “peripheraltype subtropical high” and “small subtropical high，”and the probability of largescale hail weather was small.
2011, 39(6):791-795.
Abstract:
Based on the fog and haze data from 8 meteorological stations in Wenzhou，the temporal and spatial climatic characteristics and the variation regularities of fog and haze days in recent 40 years are analyzed．The results indicate that from 1971 to 2008， the number of fog days in the urban area of Wenzhou significantly decreased． Fog days in exurban area of Wenzhou decreased slowly．Haze days in urban and exurban areas of Wenzhou increased from 1971 to 2008 as a whole， and such increase occurred mainly after 1979． During the period of 2001 to 2008， the number of haze days was the greatest in Wenzhou， with most fog and haze days in winter and least in summer． From 1971 to 2008， fog days decreased in most regions of Wenzhou， but haze days increased in all regions of Wenzhou， especially haze days increased rapidly in Urban. The relation has been found between fog， haze， precipitation， and API from the data of 2004 to 2009， based on which a forecasting model is established， with the forecasting accuracy up to 57% to 66%. The verification indicates that the relation is useful in fog and haze forecasting， and the computeraided automatic forecasting is applicable.
Based on the fog and haze data from 8 meteorological stations in Wenzhou，the temporal and spatial climatic characteristics and the variation regularities of fog and haze days in recent 40 years are analyzed．The results indicate that from 1971 to 2008， the number of fog days in the urban area of Wenzhou significantly decreased． Fog days in exurban area of Wenzhou decreased slowly．Haze days in urban and exurban areas of Wenzhou increased from 1971 to 2008 as a whole， and such increase occurred mainly after 1979． During the period of 2001 to 2008， the number of haze days was the greatest in Wenzhou， with most fog and haze days in winter and least in summer． From 1971 to 2008， fog days decreased in most regions of Wenzhou， but haze days increased in all regions of Wenzhou， especially haze days increased rapidly in Urban. The relation has been found between fog， haze， precipitation， and API from the data of 2004 to 2009， based on which a forecasting model is established， with the forecasting accuracy up to 57% to 66%. The verification indicates that the relation is useful in fog and haze forecasting， and the computeraided automatic forecasting is applicable.
22 Application of Improved Wet Q Vector Partitioning Method to Diagnosis of a Continued Heavy Rain
2011, 39(6):796-802.
Abstract:
By means of the conventional observation data and the improved wet 〖WTHX〗Q〖WTBZ〗 vector （〖WTHX〗Q〖WTBZ〗q）， a continued torrential rain process on the east side of the Qingzang Plateau between 18 and 19 July 2005 is diagnosed. The convergence field of 〖WTHX〗Q〖WTBZ〗q on 700 hPa indicated the region of the heavy rain， and the convergence center corresponded to the precipitation center. By dividing the improved ageostrophic wet 〖WTHX〗Q〖WTBZ〗 vector into two parts： parallel and perpendicular to isentropes， further research is made on the event. The results show that the largescale and mesoscale systems had different forcing of vertical motion on different layers. The superposition of two ascending motions produced the heavy rain. During the first phase of the continual heavy rain， the largescale ascending motion on 700 hPa was primary， while the mesoscale ascending motion was dominant in the lower and middle layers， and they caused the strong convection to develop and deep convection to form，which can reflect the area of the heavy rain more precisely. During the second phase of the heavy rain， the mesoscale ascending motion forcing was dominant. With the weakening of the heavy rain， the proportion of the largescale ascending motion increased， and the mesoscale decreased.
By means of the conventional observation data and the improved wet 〖WTHX〗Q〖WTBZ〗 vector （〖WTHX〗Q〖WTBZ〗q）， a continued torrential rain process on the east side of the Qingzang Plateau between 18 and 19 July 2005 is diagnosed. The convergence field of 〖WTHX〗Q〖WTBZ〗q on 700 hPa indicated the region of the heavy rain， and the convergence center corresponded to the precipitation center. By dividing the improved ageostrophic wet 〖WTHX〗Q〖WTBZ〗 vector into two parts： parallel and perpendicular to isentropes， further research is made on the event. The results show that the largescale and mesoscale systems had different forcing of vertical motion on different layers. The superposition of two ascending motions produced the heavy rain. During the first phase of the continual heavy rain， the largescale ascending motion on 700 hPa was primary， while the mesoscale ascending motion was dominant in the lower and middle layers， and they caused the strong convection to develop and deep convection to form，which can reflect the area of the heavy rain more precisely. During the second phase of the heavy rain， the mesoscale ascending motion forcing was dominant. With the weakening of the heavy rain， the proportion of the largescale ascending motion increased， and the mesoscale decreased.
2011, 39(6):803-807.
Abstract:
The synchronous observation of submicrosecond electromagnetic changes resulted from lightning is described. A newtype fast/slow rangeadjustable measuring system of electric field changes is developed. The equipment can be used to observe lighting in different environments in combination with magnetic measuring devices. The software of the system based on Labwindows/CVI with the PCI5105 card is discussed. The main advantages of this system include high sampling rate， high capacity， multiple parameters， and synchronous measurement. This system was used to observe lighting flashes and analyze lightning physical processes in a field experiment.
The synchronous observation of submicrosecond electromagnetic changes resulted from lightning is described. A newtype fast/slow rangeadjustable measuring system of electric field changes is developed. The equipment can be used to observe lighting in different environments in combination with magnetic measuring devices. The software of the system based on Labwindows/CVI with the PCI5105 card is discussed. The main advantages of this system include high sampling rate， high capacity， multiple parameters， and synchronous measurement. This system was used to observe lighting flashes and analyze lightning physical processes in a field experiment.
2011, 39(6):808-813.
Abstract:
Based on the site error model for optimizing the lightning location data, about 200 lightning flash samples in Pingliang, Gansu Province are corrected and compared with the radar echoes of over 35 dBz at the corresponding cloud top height of over 7 km. The results show that the uncorrected CG (CloudtoGround lightning flashes) locations are tens of kilometers apart from the radar echo area, and the corrected CG lightning locations are very close to the strong radar echo area. The results also show that the residual errors between the corrected and real flash directions are less than 0.5° after correcting. The site errors of the lightning location system can be minimized by this optimizing model, and this parameterization method of the site errors estimation is very important for the development of nowcasting lightning forecast.
Based on the site error model for optimizing the lightning location data, about 200 lightning flash samples in Pingliang, Gansu Province are corrected and compared with the radar echoes of over 35 dBz at the corresponding cloud top height of over 7 km. The results show that the uncorrected CG (CloudtoGround lightning flashes) locations are tens of kilometers apart from the radar echo area, and the corrected CG lightning locations are very close to the strong radar echo area. The results also show that the residual errors between the corrected and real flash directions are less than 0.5° after correcting. The site errors of the lightning location system can be minimized by this optimizing model, and this parameterization method of the site errors estimation is very important for the development of nowcasting lightning forecast.
2011, 39(6):814-817.
Abstract:
With the improvement of ground meteorological detection technology and the development of computer data processing technology， the meteorological data documenting advanced greatly， no longer using manual recoding and calculation， and so the auditing emphases are changed to the anaylsis and control of data quality and the rationality of visual measurements. The process of data documenting and auditing of ground meteological observation is described， and some issues， such as the categories， formats and wording of the remarks files， as well as the common errors encountered in maintaining and auditing of ground meteorological observation data files， are discussed in detail， to provide references for observaers to improve the quality of observation data of ground automatic meteorological stations.
With the improvement of ground meteorological detection technology and the development of computer data processing technology， the meteorological data documenting advanced greatly， no longer using manual recoding and calculation， and so the auditing emphases are changed to the anaylsis and control of data quality and the rationality of visual measurements. The process of data documenting and auditing of ground meteological observation is described， and some issues， such as the categories， formats and wording of the remarks files， as well as the common errors encountered in maintaining and auditing of ground meteorological observation data files， are discussed in detail， to provide references for observaers to improve the quality of observation data of ground automatic meteorological stations.
2011, 39(6):818-822.
Abstract:
Time synchronization has a major impact on the quality of images received by satellites in the polar orbiting meteorological satellite data acquisition system. Therefore， TimeServer is needed to provide criterion time for the system to ensure complete reception on schedule. The GPS clock is used as the reference source of TimeServer for its stabilization and accuracy. In order to ensure that the GPSTimeServer works normally， it is necessary to monitor its status. The monitoring and management functions through the serial communication on the TimeServer is based on the Visual Basic 6.0. The monitoring function provides an important basis for fault finding， troubleshooting， and recording. The management functions include inquiry and subfunction setting， which is convenient for users to operate.
Time synchronization has a major impact on the quality of images received by satellites in the polar orbiting meteorological satellite data acquisition system. Therefore， TimeServer is needed to provide criterion time for the system to ensure complete reception on schedule. The GPS clock is used as the reference source of TimeServer for its stabilization and accuracy. In order to ensure that the GPSTimeServer works normally， it is necessary to monitor its status. The monitoring and management functions through the serial communication on the TimeServer is based on the Visual Basic 6.0. The monitoring function provides an important basis for fault finding， troubleshooting， and recording. The management functions include inquiry and subfunction setting， which is convenient for users to operate.
2011, 39(6):823-827.
Abstract:
The thunders and lightning occur in the geospace and thus have obvious spatiotemporal characters. It is very useful to analyze the spatial and temporal distribution characteristics of the lightning data with the support of the GIS platform. The visual map component for lightning data (thunder map) is designed and developed to realize the visual display and analysis of various lightning data on the GIS platform, based on the ArcEngine SDK in ArcGIS, one of the mainstream GIS software to implement this component and divided the structure into three logical layers (data definition layer, data function layer, and map UI layer). A case to illustrate successfully the application of this component is given.
The thunders and lightning occur in the geospace and thus have obvious spatiotemporal characters. It is very useful to analyze the spatial and temporal distribution characteristics of the lightning data with the support of the GIS platform. The visual map component for lightning data (thunder map) is designed and developed to realize the visual display and analysis of various lightning data on the GIS platform, based on the ArcEngine SDK in ArcGIS, one of the mainstream GIS software to implement this component and divided the structure into three logical layers (data definition layer, data function layer, and map UI layer). A case to illustrate successfully the application of this component is given.
2011, 39(6):828-833.
Abstract:
The design and implementation of the Tianjin mesoscale numerical weather prediction system is to fulfill the requirements of mesoscale numerical weather prediction operation at provincial level meteorological offices. The Tianjin mesoscale numerical weather prediction system is composed of the highperformance computer system, the mesoscale numerical weather prediction model, and the operational working procedure. Its design and implementation involve the construction of the highperformance computer system, the design of the operational transfer of mesoscale numerical model data, and the system monitoring process. The system implementation includes the selection, design and installation of the highperformance computer system, as well as the operational data flow of the mesoscale numerical model and the deployment of the system monitoring process. The Tianjin mesoscale numerical weather prediction system has accomplished the weather forecasting service task for Olympic Games, which has been put into operation.
The design and implementation of the Tianjin mesoscale numerical weather prediction system is to fulfill the requirements of mesoscale numerical weather prediction operation at provincial level meteorological offices. The Tianjin mesoscale numerical weather prediction system is composed of the highperformance computer system, the mesoscale numerical weather prediction model, and the operational working procedure. Its design and implementation involve the construction of the highperformance computer system, the design of the operational transfer of mesoscale numerical model data, and the system monitoring process. The system implementation includes the selection, design and installation of the highperformance computer system, as well as the operational data flow of the mesoscale numerical model and the deployment of the system monitoring process. The Tianjin mesoscale numerical weather prediction system has accomplished the weather forecasting service task for Olympic Games, which has been put into operation.
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.