Volume 37,Issue 2,2009 Table of Contents
2009, 37(2):129-134.
Abstract:
In order to know the forecasting performance of the localized MM5 model, the forecast capabilities of MM5 in precipitation, extreme temperature and humidity are verified and assessed in statistical methods according to the forecast results in the later half of 2007 with the NCEP and T213 initial fields in the Hebei and BeijingTianjin region. The results indicate: (1) The accuracy of fineorrainy forecasting is higher, with better value for reference, but for grade forecasting, the usability of forecasts decreases with the increasing of lead time and precipitation intensity. Generally speaking, the precipitation forecast based on the NCEP initial field is better than that based on T213. (2) For the forecasts of daily extreme temperature, the minimum temperature forecasts are better than maximum temperature forecasts; the accuracy of the maximum temperature forecasts with the T213 initial fields is better, while that of the minimum temperature forecasts with the NCEP initial fields is better. (3) The result of humidity at 08:00 shows that, there is no obvious difference in the results between two initial fields, with the absolute error being about 15%.
In order to know the forecasting performance of the localized MM5 model, the forecast capabilities of MM5 in precipitation, extreme temperature and humidity are verified and assessed in statistical methods according to the forecast results in the later half of 2007 with the NCEP and T213 initial fields in the Hebei and BeijingTianjin region. The results indicate: (1) The accuracy of fineorrainy forecasting is higher, with better value for reference, but for grade forecasting, the usability of forecasts decreases with the increasing of lead time and precipitation intensity. Generally speaking, the precipitation forecast based on the NCEP initial field is better than that based on T213. (2) For the forecasts of daily extreme temperature, the minimum temperature forecasts are better than maximum temperature forecasts; the accuracy of the maximum temperature forecasts with the T213 initial fields is better, while that of the minimum temperature forecasts with the NCEP initial fields is better. (3) The result of humidity at 08:00 shows that, there is no obvious difference in the results between two initial fields, with the absolute error being about 15%.
2009, 37(2):135-140.
Abstract:
Based on the T213 numerical prediction products and the routine radiosonde and surface observation data, the development and movement of the typhoon Chanchu (No.0601) are studied by means of the GRAPESbased numerical experiment. The results show that the GRAPES model has a good ability to forecast the intensification, moving track, and heavy rainfall caused by Chanchu. This model simulated out well the landing spot and especially the track of Chanchu, which made an abrupt clockwise turning from west to north in the central South China Sea. By analysis of the 500 hPa geopotential height and the sealevel pressure fields, as well as temperature, vertical motion and vortex, it is showed that the abrupt turning of the track was related to the adjustment of the general circulation, the movement of cold air, and its own dissymmetrical structure.
Based on the T213 numerical prediction products and the routine radiosonde and surface observation data, the development and movement of the typhoon Chanchu (No.0601) are studied by means of the GRAPESbased numerical experiment. The results show that the GRAPES model has a good ability to forecast the intensification, moving track, and heavy rainfall caused by Chanchu. This model simulated out well the landing spot and especially the track of Chanchu, which made an abrupt clockwise turning from west to north in the central South China Sea. By analysis of the 500 hPa geopotential height and the sealevel pressure fields, as well as temperature, vertical motion and vortex, it is showed that the abrupt turning of the track was related to the adjustment of the general circulation, the movement of cold air, and its own dissymmetrical structure.
2009, 37(2):141-144.
Abstract:
By using local surface temperature and high temporalspatial resolution numerical forecasting products of GFS (Global Forecast System) provided by NCEP,the preliminary forecast equations for daily average, highest and lowest temperature within 24 and 48 hours are established with the SPSS (Statistical Product and Service Solution) stepwise regression method, and the daytoday rolling forecasting was made with the Kalman filtering method. The results from June 2005 to May 2007 show that the average temperature forecast performed the best, the minimum the second, and the maximum the worst; the errors of forecasts increase with time; the significance of the factors differs in different seasons, smaller in autumn, higher in winter. The findings can be used as reference in forecasting operation.
By using local surface temperature and high temporalspatial resolution numerical forecasting products of GFS (Global Forecast System) provided by NCEP,the preliminary forecast equations for daily average, highest and lowest temperature within 24 and 48 hours are established with the SPSS (Statistical Product and Service Solution) stepwise regression method, and the daytoday rolling forecasting was made with the Kalman filtering method. The results from June 2005 to May 2007 show that the average temperature forecast performed the best, the minimum the second, and the maximum the worst; the errors of forecasts increase with time; the significance of the factors differs in different seasons, smaller in autumn, higher in winter. The findings can be used as reference in forecasting operation.
2009, 37(2):149-151.
Abstract:
By means of Support Vector Machine (SVM) and nine meteorological element data near the surface layer before heavy fog occurring in December and November from 1971 to 2000 (air temperature, precipitation, visibility, wind speed, wind direction, relative humidity, and overall and low cloud cover), a 24hour heavy fog forecast model for the highway in Shaanxi Province is developed. The model, based on the Gauss kernel function, has put to trial use and gets satisfactory TS scores through simulating and training in fog forecasting.
By means of Support Vector Machine (SVM) and nine meteorological element data near the surface layer before heavy fog occurring in December and November from 1971 to 2000 (air temperature, precipitation, visibility, wind speed, wind direction, relative humidity, and overall and low cloud cover), a 24hour heavy fog forecast model for the highway in Shaanxi Province is developed. The model, based on the Gauss kernel function, has put to trial use and gets satisfactory TS scores through simulating and training in fog forecasting.
2009, 37(2):152-155.
Abstract:
Based on the conventional weather data, Doppler radar data, wind profile radar data, and automatic weather station data，an analysis is made of two local convective events. The results suggest that the local torrential rain occurred on 13 July 2007 can be attributed to the uplifting of southeast streams at lower levels forced by mountains, and the local convection occurred on 10 July 2007 was triggered by an ABL convergence line. The evolvement of weather conditions can be identified by the wind profile data, and the ABL convergence line by radar echoes and automatic weather station data. Considering the topography in Beijing areas, in combination with the close radar monitoring, the forecasting and warning of local severe convective weather can be improved greatly.
Based on the conventional weather data, Doppler radar data, wind profile radar data, and automatic weather station data，an analysis is made of two local convective events. The results suggest that the local torrential rain occurred on 13 July 2007 can be attributed to the uplifting of southeast streams at lower levels forced by mountains, and the local convection occurred on 10 July 2007 was triggered by an ABL convergence line. The evolvement of weather conditions can be identified by the wind profile data, and the ABL convergence line by radar echoes and automatic weather station data. Considering the topography in Beijing areas, in combination with the close radar monitoring, the forecasting and warning of local severe convective weather can be improved greatly.
2009, 37(2):156-161.
Abstract:
The comparative analysis is made of the high wind processes and formation causes of the super typhoons Krosa and Wipha landing around the boundary area of Fujian and Zhejiang provinces in 2007 by using the conventional radiosonde data, surface observation data, automatic station data, FY2C satellite image data, and the Doppler radar data. Results show that the distribution of the surface pressure field has important impact on the high winds before and after the typhoon landing, the influencing scope, and the duration of typhoon; the infrared cloud pictures from FY2C have an indicative role for determining the impact of high winds, and the time that the peripheral spiral clouds of the typhoons entered the East Sea on the FY2C infrared cloud pictures can be used as an indicator in forecasting the occurrence of high winds. The velocity products of Doppler radar can also be used as an important reference for forecasting extreme wind speeds in typhoons.
The comparative analysis is made of the high wind processes and formation causes of the super typhoons Krosa and Wipha landing around the boundary area of Fujian and Zhejiang provinces in 2007 by using the conventional radiosonde data, surface observation data, automatic station data, FY2C satellite image data, and the Doppler radar data. Results show that the distribution of the surface pressure field has important impact on the high winds before and after the typhoon landing, the influencing scope, and the duration of typhoon; the infrared cloud pictures from FY2C have an indicative role for determining the impact of high winds, and the time that the peripheral spiral clouds of the typhoons entered the East Sea on the FY2C infrared cloud pictures can be used as an indicator in forecasting the occurrence of high winds. The velocity products of Doppler radar can also be used as an important reference for forecasting extreme wind speeds in typhoons.
2009, 37(2):162-165.
Abstract:
A statistical analysis is made of the variation characteristics of fog events over the eastern Qinghai Province by means of the surface observation data from six stations over the region from 1977 to 2006. The results indicate that foggy days in the region had an uneven spatial distribution, with the high center at Menyuan (8.3 days per year, with the maximum up to 13 days per year); there were obvious annual, seasonal and daily variations in foggy days, and the number of foggy days per year decreased obviously; foggy days occurred mostly from 02:00 to 08:00, April to October, with the highest occurrence frequency in NNE or NE winds and the least in ESE and SSW winds (less than 1.5%); meanwhile, there was the highest occurrence frequency while air temperature being -1 ℃ to 5 ℃, and the relatively high occurrence frequency at higher humidity (over 88%) at various stations, except at Xining with the threshold humidity being 57%.
A statistical analysis is made of the variation characteristics of fog events over the eastern Qinghai Province by means of the surface observation data from six stations over the region from 1977 to 2006. The results indicate that foggy days in the region had an uneven spatial distribution, with the high center at Menyuan (8.3 days per year, with the maximum up to 13 days per year); there were obvious annual, seasonal and daily variations in foggy days, and the number of foggy days per year decreased obviously; foggy days occurred mostly from 02:00 to 08:00, April to October, with the highest occurrence frequency in NNE or NE winds and the least in ESE and SSW winds (less than 1.5%); meanwhile, there was the highest occurrence frequency while air temperature being -1 ℃ to 5 ℃, and the relatively high occurrence frequency at higher humidity (over 88%) at various stations, except at Xining with the threshold humidity being 57%.
2009, 37(2):166-170.
Abstract:
By means of the NCEP reanalysis data and the conventional surface observation and radiosonde data from 1981 to 2005, combining the LambJenkinson (LJ) with the traditional synoptic classification schemes, the circulation patterns for fog weather in Fuzhou are classified. It is shown that the results from the traditional and LJ schemes are almost the same in SLP (Sea Level Pressure) distribution; that is, there existed a uniform pressure field during the occurrence of heavy fog. The LJ scheme can get more detailed and complete classification results and provide important bases for objective fog forecasting in Fuzhou.
By means of the NCEP reanalysis data and the conventional surface observation and radiosonde data from 1981 to 2005, combining the LambJenkinson (LJ) with the traditional synoptic classification schemes, the circulation patterns for fog weather in Fuzhou are classified. It is shown that the results from the traditional and LJ schemes are almost the same in SLP (Sea Level Pressure) distribution; that is, there existed a uniform pressure field during the occurrence of heavy fog. The LJ scheme can get more detailed and complete classification results and provide important bases for objective fog forecasting in Fuzhou.
2009, 37(2):171-174.
Abstract:
On the basis of the records of air temperature from the northernmost meteorological station from 1963 to 2005, the characteristics of temperature change are analyzed by calculating climate trend coefficients and climate tendency. It is showed that temperature increased markedly and steadily in the last 43 years, with the annual mean temperature increased by 0. 46 ℃ per 10 years. Temperature in all months and in all seasons increased at different degrees, with the mean temperature in winter being the most sharply (0.69 ℃ per 10 years), among which the increase in February was the greatest, being 1.02 ℃ per 10 years. The increase of mean air temperature in autumn was only 0.2146 ℃ per 10 years, which was the smallest of the year. The variation tendencies of annual mean minimum temperature (0.5946 ℃ per 10 years) and extreme minimum temperature (0.7446 ℃ per 10 years) were greater than those of mean maximum temperature (0.3746 ℃ per 10 years) and extreme maximum temperature (0.2746 ℃ per 10 years). Further analysis suggests that the interdecadal warming trend of minimum temperature is more evident than that of maximum temperature.
On the basis of the records of air temperature from the northernmost meteorological station from 1963 to 2005, the characteristics of temperature change are analyzed by calculating climate trend coefficients and climate tendency. It is showed that temperature increased markedly and steadily in the last 43 years, with the annual mean temperature increased by 0. 46 ℃ per 10 years. Temperature in all months and in all seasons increased at different degrees, with the mean temperature in winter being the most sharply (0.69 ℃ per 10 years), among which the increase in February was the greatest, being 1.02 ℃ per 10 years. The increase of mean air temperature in autumn was only 0.2146 ℃ per 10 years, which was the smallest of the year. The variation tendencies of annual mean minimum temperature (0.5946 ℃ per 10 years) and extreme minimum temperature (0.7446 ℃ per 10 years) were greater than those of mean maximum temperature (0.3746 ℃ per 10 years) and extreme maximum temperature (0.2746 ℃ per 10 years). Further analysis suggests that the interdecadal warming trend of minimum temperature is more evident than that of maximum temperature.
2009, 37(2):175-180.
Abstract:
Based on the routine observation data, T213 products, and FY2C water vapor images, the circulation background, the influencing synoptic systems, and the causes of the extraordinarily serious snowstorm event occurred from 3 to 5 March 2007 in Liaoning Province are analyzed diagnostically．The results show that （1）The extreme weather event happened under the background with the circulation index being high and the most part of China being warmer,associated with gale and intense temperature decrease.（2）The Jianghuai cyclone was the most important influencing weather system; the occurrence and development of the Jianghuai cyclone were resulted from the joint effects of positive vorticity advection at high levels and warm advection at low levels in the troposphere.（3）The strong ascending motion caused by the vertical allocation of the divergence at upper levels and the convergence at lower levels is the dynamical formation and maintenance mechanism of the snowstorm. (4) The cyclone occurred in the area between polarfront and subtropical westerly jets, moved from the north of the exit area of the subtropical westerly jet to the south of the entrance area of the polarfront jet, developed intensely during the process moving from the left side of the southwest jet stream in the lower levels to the left front.（5） It is found that a dry intrusion is the important feature of intense development of the cyclone. (6) The southwest and southeast jets at the lower levels offered plentiful water moisture for the heavy storm (rain), which occurred within the warm and moist tongue at 850 hPa, whose precipitation is directly related to the temperature at 850 hPa. (7) The intense temperature decrease happened under the conditions of the development and eastward movement of the longwave trough leading to the southward movement of polar cold air, and the strong winds were resulted from the tight pressure gradient between intensely developed cyclone and strong cold high.
Based on the routine observation data, T213 products, and FY2C water vapor images, the circulation background, the influencing synoptic systems, and the causes of the extraordinarily serious snowstorm event occurred from 3 to 5 March 2007 in Liaoning Province are analyzed diagnostically．The results show that （1）The extreme weather event happened under the background with the circulation index being high and the most part of China being warmer,associated with gale and intense temperature decrease.（2）The Jianghuai cyclone was the most important influencing weather system; the occurrence and development of the Jianghuai cyclone were resulted from the joint effects of positive vorticity advection at high levels and warm advection at low levels in the troposphere.（3）The strong ascending motion caused by the vertical allocation of the divergence at upper levels and the convergence at lower levels is the dynamical formation and maintenance mechanism of the snowstorm. (4) The cyclone occurred in the area between polarfront and subtropical westerly jets, moved from the north of the exit area of the subtropical westerly jet to the south of the entrance area of the polarfront jet, developed intensely during the process moving from the left side of the southwest jet stream in the lower levels to the left front.（5） It is found that a dry intrusion is the important feature of intense development of the cyclone. (6) The southwest and southeast jets at the lower levels offered plentiful water moisture for the heavy storm (rain), which occurred within the warm and moist tongue at 850 hPa, whose precipitation is directly related to the temperature at 850 hPa. (7) The intense temperature decrease happened under the conditions of the development and eastward movement of the longwave trough leading to the southward movement of polar cold air, and the strong winds were resulted from the tight pressure gradient between intensely developed cyclone and strong cold high.
2009, 37(2):181-185.
Abstract:
Based on conventional data, AMS (Automatic Meteorological Station) data, NCEP reanalysis data of 1°×1° with a 6 h interval, and radar echo data, a squall line weather event on 11 June 2007 is analyzed comprehensively. The weather background, radar echoes, meteorological element fields are diagnosed. The results show that the squall line occurred under an unstable stratification, in which it was dry and cold at the upper level, wet and warm at the lower troposphere; its triggering mechanisms include the uppertroposphere jet, ground shear, vertical wind shear, and dry air intrusion in the middle troposphere; its energy sources include the weak ABL water vapor transportation and energy accumulation.
Based on conventional data, AMS (Automatic Meteorological Station) data, NCEP reanalysis data of 1°×1° with a 6 h interval, and radar echo data, a squall line weather event on 11 June 2007 is analyzed comprehensively. The weather background, radar echoes, meteorological element fields are diagnosed. The results show that the squall line occurred under an unstable stratification, in which it was dry and cold at the upper level, wet and warm at the lower troposphere; its triggering mechanisms include the uppertroposphere jet, ground shear, vertical wind shear, and dry air intrusion in the middle troposphere; its energy sources include the weak ABL water vapor transportation and energy accumulation.
2009, 37(2):186-189.
Abstract:
Based on the composite diagnostic index, the relationship of meteorological factors (such as the daily average temperature and precipitation) between the forecasting year and any historical year during the growing season of American wheat is investigated, and the forecasting model based on the ground meteorological data is built by using the historical meteorological influence index. Meanwhile another forecasting model is built, using the monthly average sea surface temperature of the West Pacific Ocean and the circulation data at 500 hPa in the Northern Hemisphere as the main influencing factors. The ensemble forecasting model is built based on the stability of various models by the weighted method. The forecasting verification for 1995-2004 and experiments for 2005 and 2006 indicate that the accuracy of the ensemble model is over 92% and can meet the needs of operational service.
Based on the composite diagnostic index, the relationship of meteorological factors (such as the daily average temperature and precipitation) between the forecasting year and any historical year during the growing season of American wheat is investigated, and the forecasting model based on the ground meteorological data is built by using the historical meteorological influence index. Meanwhile another forecasting model is built, using the monthly average sea surface temperature of the West Pacific Ocean and the circulation data at 500 hPa in the Northern Hemisphere as the main influencing factors. The ensemble forecasting model is built based on the stability of various models by the weighted method. The forecasting verification for 1995-2004 and experiments for 2005 and 2006 indicate that the accuracy of the ensemble model is over 92% and can meet the needs of operational service.
2009, 37(2):190-195.
Abstract:
According to the 50year meteorological data of Chaozhou, the characteristics and regularities of climate change are analyzed. It is found in the past 20 years: the temperature rose gradually; high temperature days in summer increased significantly; low temperature and frost days in winter, low temperature and rainy weather in spring, and chilling damage in autumn in risk of significant harm reduced; seasonal precipitation changes were more evident: in the last decade，spring rainfall decreased and summer rainfall increased obviously; the occurrence probabilities of heavy rainfall and other extreme weather events increased. The influences of climate change on the growth, development and yields of crops in Chaozhou are analyzed, and the agrometeorological suggestions and countermeasures, such as the adjustment of planting season and planting layout, are proposed, to provide references for agricultural production of Chaozhou to adapt to climate change.
According to the 50year meteorological data of Chaozhou, the characteristics and regularities of climate change are analyzed. It is found in the past 20 years: the temperature rose gradually; high temperature days in summer increased significantly; low temperature and frost days in winter, low temperature and rainy weather in spring, and chilling damage in autumn in risk of significant harm reduced; seasonal precipitation changes were more evident: in the last decade，spring rainfall decreased and summer rainfall increased obviously; the occurrence probabilities of heavy rainfall and other extreme weather events increased. The influences of climate change on the growth, development and yields of crops in Chaozhou are analyzed, and the agrometeorological suggestions and countermeasures, such as the adjustment of planting season and planting layout, are proposed, to provide references for agricultural production of Chaozhou to adapt to climate change.
2009, 37(2):196-197.
Abstract:
2009, 37(2):198-204.
Abstract:
By means of the conventional weather observation data from 5 stations from 1971 to 2004 and the data from ground automatic weather stations from 2005 to 2006 in the eastern Hexi corridor, the evolution and distribution of nearsurface wind speed and wind energy are analyzed by the statistical method. The results show that the change of the environmental wind speed was quite stable, but the wind speed decreased obviously where the environmental variation was bigger. The regional distribution characteristics of wind energy are that the wind energy was the biggest in the mountainous areas, the second along the Hexi corridor in the desert belt, and the smallest in the Wuwei oasis basin. The annual mean wind speed is greater than 3.5 m/s, and the mean wind speeds of all months are greater than 3.0 m/s. The jumping of both wind direction and wind speed is unobvious in whole year. The daily mean number of effective wind energy hours is greater than 13.9, and the annual mean number of effective wind energy hours is greater than 5000 hours in the southern mountainous area, where there is great potential for the development of wind resources. The annual mean wind speed is only 2.7 m/s, bigger from march to July, with the daily mean number of effective wind energy hours being 8.7 hours, the annual mean number of effective wind energy hours being 2913 hours, and the annual mean effective wind energy density being 82.7 W/m2 over the northern desert areas, where the wind energy can be utilized seasonally. The various wind energy parameters are smaller in the Liangzhou oasis basin, where wind power generation, therefore, is not suitable. The utilization prospects of wind energy are analyzed according to the regional climate characteristics of wind power generation.
By means of the conventional weather observation data from 5 stations from 1971 to 2004 and the data from ground automatic weather stations from 2005 to 2006 in the eastern Hexi corridor, the evolution and distribution of nearsurface wind speed and wind energy are analyzed by the statistical method. The results show that the change of the environmental wind speed was quite stable, but the wind speed decreased obviously where the environmental variation was bigger. The regional distribution characteristics of wind energy are that the wind energy was the biggest in the mountainous areas, the second along the Hexi corridor in the desert belt, and the smallest in the Wuwei oasis basin. The annual mean wind speed is greater than 3.5 m/s, and the mean wind speeds of all months are greater than 3.0 m/s. The jumping of both wind direction and wind speed is unobvious in whole year. The daily mean number of effective wind energy hours is greater than 13.9, and the annual mean number of effective wind energy hours is greater than 5000 hours in the southern mountainous area, where there is great potential for the development of wind resources. The annual mean wind speed is only 2.7 m/s, bigger from march to July, with the daily mean number of effective wind energy hours being 8.7 hours, the annual mean number of effective wind energy hours being 2913 hours, and the annual mean effective wind energy density being 82.7 W/m2 over the northern desert areas, where the wind energy can be utilized seasonally. The various wind energy parameters are smaller in the Liangzhou oasis basin, where wind power generation, therefore, is not suitable. The utilization prospects of wind energy are analyzed according to the regional climate characteristics of wind power generation.
2009, 37(2):205-208.
Abstract:
Based on the survey on wind disasters in Hubei Province from 1965 to 2005, through analyzing some indexes, such as the frequency of wind disaster in each area and the loss of people and property, impact assessments on wind disaster for various areas are made. By means of the indexes as damagesuffering population and disasteraffected area, the grades of wind disaster are given, and in combination with the wind disaster frequency, the influence degrees of wind disasters are determined. According to the characteristics of disasterinducing factors and the analysis of vulnerability of hazardbearing bodies, using the hazard assessment model, an analytical chart of winddisaster risk degree is presented. It is shown that the Three Gorges valley and the eastern Jianghan Plain are the highestrisk areas of wind disaster.
Based on the survey on wind disasters in Hubei Province from 1965 to 2005, through analyzing some indexes, such as the frequency of wind disaster in each area and the loss of people and property, impact assessments on wind disaster for various areas are made. By means of the indexes as damagesuffering population and disasteraffected area, the grades of wind disaster are given, and in combination with the wind disaster frequency, the influence degrees of wind disasters are determined. According to the characteristics of disasterinducing factors and the analysis of vulnerability of hazardbearing bodies, using the hazard assessment model, an analytical chart of winddisaster risk degree is presented. It is shown that the Three Gorges valley and the eastern Jianghan Plain are the highestrisk areas of wind disaster.
2009, 37(2):209-215.
Abstract:
By using the natural complex randomization method, the accuracy analysis is made of four kinds of statistical test schemes generally used in precipitation enhancement effectiveness evaluation, in which the “false effectiveness” is used to reflect the accuracy of evaluation to find out the different factors affecting the accuracy and to compare the accuracy of the different statistical schemes. It is found that the accuracy of the evaluation is relative to the quantityies of operation samples and historical samples. The accuracy increases with the increasing quantity of samples with the increment becoming gentle at last. Under the same condition, the historical regression method is more accurate than the others. Under the prescribed significance level, the historical regression method needs the least samples to reach the approximately same confidence level, while the double ratio analysis method and the comparative test need more samples, and the series experiment needs the most. The regression ratio method, a seldomly used statistical analysis method, is also discussed. The “false effectiveness” analysis concludes that the regression method is more accurate than the historical regression method.
By using the natural complex randomization method, the accuracy analysis is made of four kinds of statistical test schemes generally used in precipitation enhancement effectiveness evaluation, in which the “false effectiveness” is used to reflect the accuracy of evaluation to find out the different factors affecting the accuracy and to compare the accuracy of the different statistical schemes. It is found that the accuracy of the evaluation is relative to the quantityies of operation samples and historical samples. The accuracy increases with the increasing quantity of samples with the increment becoming gentle at last. Under the same condition, the historical regression method is more accurate than the others. Under the prescribed significance level, the historical regression method needs the least samples to reach the approximately same confidence level, while the double ratio analysis method and the comparative test need more samples, and the series experiment needs the most. The regression ratio method, a seldomly used statistical analysis method, is also discussed. The “false effectiveness” analysis concludes that the regression method is more accurate than the historical regression method.
2009, 37(2):216-220.
Abstract:
By means of the recent 9year lightning disaster and 45year thunderstorm day and 4year cloudtoground lightning flash data in Jiangsu Province, an analysis is made of the distributions of lightning disasters in 13 cities based on the background of natural and human culture environment in Jiangsu Province. It is point out that lightning disasters mainly occur from June to August, and damages are mainly found in physical devices and electricity and electronic systems, with Wuxi and Suzhou being most typical. Vulnerability indexes are extracted and calculated, and the comprehensive assessments are made on these indexes using the method of the principal component analysis with SAS software. The results indicate that the regional thunder disaster vulnerability is depended on not only the sensitivity of the regional natural condition to the environmental variation of the lightning magnetic field and but also the bearing capacity of the social system in the region to lightning disasters. The vulnerability regionalization chart of lightning disasters in Jiangsu Province, based on cluster analysis, is given, which can provide a scientific basis for regional lightning protection and disaster reduction.
By means of the recent 9year lightning disaster and 45year thunderstorm day and 4year cloudtoground lightning flash data in Jiangsu Province, an analysis is made of the distributions of lightning disasters in 13 cities based on the background of natural and human culture environment in Jiangsu Province. It is point out that lightning disasters mainly occur from June to August, and damages are mainly found in physical devices and electricity and electronic systems, with Wuxi and Suzhou being most typical. Vulnerability indexes are extracted and calculated, and the comprehensive assessments are made on these indexes using the method of the principal component analysis with SAS software. The results indicate that the regional thunder disaster vulnerability is depended on not only the sensitivity of the regional natural condition to the environmental variation of the lightning magnetic field and but also the bearing capacity of the social system in the region to lightning disasters. The vulnerability regionalization chart of lightning disasters in Jiangsu Province, based on cluster analysis, is given, which can provide a scientific basis for regional lightning protection and disaster reduction.
2009, 37(2):221-223.
Abstract:
The PearsonType Ⅲ and the ExtremeValue TypeⅠ curves are widely used in China and abroad for calculating the maximal wind speeds. Based on the 10minute mean maximum wind speed data of Qianxian and Fufeng (Shanxi Province) from 1972 to 2004, by using the methods of the PearsonType Ⅲ, ExtremeValue TypeⅠcurves, the extreme values of the 10minute mean maximum wind speed for occurring once every 30 and 50 years are estimated. The results show that according to empirical scattering points and the fitting degree of the theoretical curve, the methods of PearsonType Ⅲ and ExtremeValue Type Ⅰ distribution can be used to adjust the calculation parameters repeatedly. Special attention should be paid to the fitting of small probability events to make the fitting of theoretical curve satisfy the needs of users.
The PearsonType Ⅲ and the ExtremeValue TypeⅠ curves are widely used in China and abroad for calculating the maximal wind speeds. Based on the 10minute mean maximum wind speed data of Qianxian and Fufeng (Shanxi Province) from 1972 to 2004, by using the methods of the PearsonType Ⅲ, ExtremeValue TypeⅠcurves, the extreme values of the 10minute mean maximum wind speed for occurring once every 30 and 50 years are estimated. The results show that according to empirical scattering points and the fitting degree of the theoretical curve, the methods of PearsonType Ⅲ and ExtremeValue Type Ⅰ distribution can be used to adjust the calculation parameters repeatedly. Special attention should be paid to the fitting of small probability events to make the fitting of theoretical curve satisfy the needs of users.
2009, 37(2):224-229.
Abstract:
By means of the radial velocity and reflectivity data of Doppler radar precipitation products in Spring in the northern and central part of Guangdong, classification is conducted on the precipitation processes with potential for rain enhancement, and the vertically integrated liquid, intensity, and echomoving velocity are statistically analyzed. The best operation chances of rain enhancement for different cloud systems are presented. The appropriate operation heights for rain enhancement in spring in the northern and central part of Guangdong are given by analyzing echo top heights and temperature. The instability conditions such as the Convective Available Potential Energy (CAPE), influencing systems, and water vapor influx divergence favorable to rain enhancement, are analyzed. As an example, the application of the newgeneration weather radar products to the operation of rain enhancement is discussed.
By means of the radial velocity and reflectivity data of Doppler radar precipitation products in Spring in the northern and central part of Guangdong, classification is conducted on the precipitation processes with potential for rain enhancement, and the vertically integrated liquid, intensity, and echomoving velocity are statistically analyzed. The best operation chances of rain enhancement for different cloud systems are presented. The appropriate operation heights for rain enhancement in spring in the northern and central part of Guangdong are given by analyzing echo top heights and temperature. The instability conditions such as the Convective Available Potential Energy (CAPE), influencing systems, and water vapor influx divergence favorable to rain enhancement, are analyzed. As an example, the application of the newgeneration weather radar products to the operation of rain enhancement is discussed.
2009, 37(2):230-233.
Abstract:
The evolutionary trends of storm cells in three severe weather events occurred in 2005 and 2006 in Shandong Province are analyzed by means of CINRAD/SA data from the Jinan radar station. The results indicate that there appeared synchronous increase in cellbased CVIL and maximumreflectivity heights in some severe storm cells before hailing on the ground, with the height being 6 km or higher and CVIL being over 18 kg/m2; and there appeared synchronous decrease before violent surface wind occurring with the height being 2 km or lower and CVIL being at least 10 kg/m2. The lead time of 7 to 20 minutes for hailwarning and that of 0 to 9 minutes for violent surface wind warning are obtained.
The evolutionary trends of storm cells in three severe weather events occurred in 2005 and 2006 in Shandong Province are analyzed by means of CINRAD/SA data from the Jinan radar station. The results indicate that there appeared synchronous increase in cellbased CVIL and maximumreflectivity heights in some severe storm cells before hailing on the ground, with the height being 6 km or higher and CVIL being over 18 kg/m2; and there appeared synchronous decrease before violent surface wind occurring with the height being 2 km or lower and CVIL being at least 10 kg/m2. The lead time of 7 to 20 minutes for hailwarning and that of 0 to 9 minutes for violent surface wind warning are obtained.
2009, 37(2):234-238.
Abstract:
The FY-2C meteorological satellite launched by China provides reliable data for estimating solar radiation reaching the earth surface. Solar radiation in three provinces (Henan, Hubei,and Hunan) of the central China is estimated, respectively, through the artificial neural network and statistical methods with FY-2C data. The results show: (1) the FY-2C data can be used to estimate solar radiation, with five bands of FY-2C contributed to the retrieval of solar radiation; (2) the neural network method is superior to the statistical method; (3) the differences in spatial and temporal scopes between satellite and ground observation result in the errors of solar radiation estimation with FY-2C.
The FY-2C meteorological satellite launched by China provides reliable data for estimating solar radiation reaching the earth surface. Solar radiation in three provinces (Henan, Hubei,and Hunan) of the central China is estimated, respectively, through the artificial neural network and statistical methods with FY-2C data. The results show: (1) the FY-2C data can be used to estimate solar radiation, with five bands of FY-2C contributed to the retrieval of solar radiation; (2) the neural network method is superior to the statistical method; (3) the differences in spatial and temporal scopes between satellite and ground observation result in the errors of solar radiation estimation with FY-2C.
2009, 37(2):239-242.
Abstract:
For the purpose of comparison of Slantpath Water Vapor (SWV) retrieved from a GPS receiver and a microwave radiometer (MR), a campaign design is completed to control the MR to point to a GPS satellite automatically to measure the SWV along the path between GPS satellite and MR. Without changing the hardware of MR, a designed software is set up to operate MR to focus on a GPS satellite using the temporal and positional parameters produced by a GPS receiver. This design is feasible automatically in allweather, which ensures the representativeness and objectivity of the observations, and reduces the expenditure for hiring observers. The preliminary results show that MR can trace well the GPS satellites to retrieve SWV with a satisfactory accuracy by using this campaign design.
For the purpose of comparison of Slantpath Water Vapor (SWV) retrieved from a GPS receiver and a microwave radiometer (MR), a campaign design is completed to control the MR to point to a GPS satellite automatically to measure the SWV along the path between GPS satellite and MR. Without changing the hardware of MR, a designed software is set up to operate MR to focus on a GPS satellite using the temporal and positional parameters produced by a GPS receiver. This design is feasible automatically in allweather, which ensures the representativeness and objectivity of the observations, and reduces the expenditure for hiring observers. The preliminary results show that MR can trace well the GPS satellites to retrieve SWV with a satisfactory accuracy by using this campaign design.
2009, 37(2):243-247.
Abstract:
By means of several nonconventional observational data, a local severe convective weather even on June 27 2006 in Beijing is studied. The results show that two mesoscale convective cloud clusters and the surface mesoscale convergence line played the triggering role in the heavy rain process, and the urban heat island provided the thermodynamic condition. The measurements of the groundbased 12channl microwave radiometer have good indicative significance to the occurrence of heavy rainfall. The rapid increase (decrease) of Liquid Water Content can be used as an indicator in forecasting the beginning (ending) of heavy rainfall. The continuous observation data from wind profile radar can provide detailed information about a convective system partly, such as the lower and middlelevel wind shears, warm advection, and smallscale lowpressure systems, which are of significance to the formation and maintenance of heavy rainfall.
By means of several nonconventional observational data, a local severe convective weather even on June 27 2006 in Beijing is studied. The results show that two mesoscale convective cloud clusters and the surface mesoscale convergence line played the triggering role in the heavy rain process, and the urban heat island provided the thermodynamic condition. The measurements of the groundbased 12channl microwave radiometer have good indicative significance to the occurrence of heavy rainfall. The rapid increase (decrease) of Liquid Water Content can be used as an indicator in forecasting the beginning (ending) of heavy rainfall. The continuous observation data from wind profile radar can provide detailed information about a convective system partly, such as the lower and middlelevel wind shears, warm advection, and smallscale lowpressure systems, which are of significance to the formation and maintenance of heavy rainfall.
2009, 37(2):248-252.
Abstract:
Based on the time calibrating technology with GPS and the actual situation of the CINRAD radar at Jinan, combining software with hardware, the automatic timecalibrating system with GPS for CINRAD data processing system without Internet connection was developed. With the system, the rectification rate reaches 100% within the calibrating time interval, and the time precision of the system reaches the second level, which completely satisfy the related requirements. This system has many advantages: real time, on line, automatic time calibration, safe, reliable, convenient to supervise, etc. and can take place of the manual approach and improve the radar data quality.
Based on the time calibrating technology with GPS and the actual situation of the CINRAD radar at Jinan, combining software with hardware, the automatic timecalibrating system with GPS for CINRAD data processing system without Internet connection was developed. With the system, the rectification rate reaches 100% within the calibrating time interval, and the time precision of the system reaches the second level, which completely satisfy the related requirements. This system has many advantages: real time, on line, automatic time calibration, safe, reliable, convenient to supervise, etc. and can take place of the manual approach and improve the radar data quality.
2009, 37(2):253-256.
Abstract:
The automatic calibration system for wind speed sensors developed by the Guangdong Provincial Atmosphere Observation and Technology Center is mainly used for calibrating windspeed sensors automatically equipped on the all types of automatic weather stations, which are used widely across China. The calibration system is highly automatic and easy to operate and control. An introduction is made to the design and development of the system and the realization of automatic control for the system, as well as the related hardware and software.
The automatic calibration system for wind speed sensors developed by the Guangdong Provincial Atmosphere Observation and Technology Center is mainly used for calibrating windspeed sensors automatically equipped on the all types of automatic weather stations, which are used widely across China. The calibration system is highly automatic and easy to operate and control. An introduction is made to the design and development of the system and the realization of automatic control for the system, as well as the related hardware and software.
External LinksChina Meteorological AdministrationCMA Meteorological Observation CentreChinese Academy of Meteorological SciencesBeijing Meteorological ServiceNational Satellite Meteorological Center
You are thevisitors
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.