Volume 42,Issue 3,2014 Table of Contents
2014, 42(3):359-363.
Abstract:
re discrimination indexes with practical significance. By means of continuous observation data from automatic weather stations, combined with the artificially observed weather phenomena records, based on the research findings on the formation causes of dew, frost, and freezing, the basic indicators qualified as a comprehensive criterion (air temperature, relative humidity, ground temperature, air grass surface temperature, and near surface air temperature) are selected as the main factors, considering the influence of rainfall and weather conditions on the formation of these weather phenomena. The minute to minute observations and artificially observed weather phenomena records of two stations are used for statistical analysis. After factor selection and indicator determination, by means of the multi element combination method, the discrimination indexes of dew, frost, and freezing occurrence under the natural environment are extracted, which are satisfactory with a fitting rate of above 80%. These indexes can be used to provide references for further understanding of the occurrence and variation regularities of these weather phenomena to provide the reference and the basis for automatic weather phenomena observation.
re discrimination indexes with practical significance. By means of continuous observation data from automatic weather stations, combined with the artificially observed weather phenomena records, based on the research findings on the formation causes of dew, frost, and freezing, the basic indicators qualified as a comprehensive criterion (air temperature, relative humidity, ground temperature, air grass surface temperature, and near surface air temperature) are selected as the main factors, considering the influence of rainfall and weather conditions on the formation of these weather phenomena. The minute to minute observations and artificially observed weather phenomena records of two stations are used for statistical analysis. After factor selection and indicator determination, by means of the multi element combination method, the discrimination indexes of dew, frost, and freezing occurrence under the natural environment are extracted, which are satisfactory with a fitting rate of above 80%. These indexes can be used to provide references for further understanding of the occurrence and variation regularities of these weather phenomena to provide the reference and the basis for automatic weather phenomena observation.
2 Analysis of Dual Polarization Weather Radar Rainfall Measuring Errors and Hydrometeor Identification
2014, 42(3):364-372.
Abstract:
The data from C band dual polarization weather radar and rainfall data from automatic weather stations during 12 synoptic processes in 2011 in Beijing are used for the value distribution calculation of ZDR, KDP and ρhv, with emphases on the effectiveness and errors of rainfall measuring by means of four radar rainfall estimation equations. The application of dual polarization weather radar products to hydrometeors identification is discussed by using some actual examples. It is concluded: (1) ZDR, KDP and ρhv can be enlarging gradually as rainfall intensity increasing; ZDR of hail is negative, and KDP of hail is larger than that of heavy rains, but smaller than that of torrential rains; ρhvof both light and moderate rainfall exceed 090, but the mean value of hails is only 0804 (2) The four radar rainfall estimation equations all overvalue the light and moderate rains and underestimate heavy rains, but the measuring errors of three rainfall estimation equations containing ZDR and KDP are smaller than that of the 〖WTBX〗I〖KG-*8〗〖CD*2〗〖KG-*8〗Z〖WTBZ〗H equation. As for short term rainstorms, the effectiveness of these three equations has obvious improvement, and the best is the I〖CD*2〗KDP〖CD*2〗〖KG-*8〗ZDR equation. (3) The case analysis of hydrometeors identification indicates that the estimate of hydrometeors (such as hail) is more direct and effective by using dual polarization products, which can reveal the hydrometeor phase state more clearly and judge the height of the 0 ℃ layer bright zone.
The data from C band dual polarization weather radar and rainfall data from automatic weather stations during 12 synoptic processes in 2011 in Beijing are used for the value distribution calculation of ZDR, KDP and ρhv, with emphases on the effectiveness and errors of rainfall measuring by means of four radar rainfall estimation equations. The application of dual polarization weather radar products to hydrometeors identification is discussed by using some actual examples. It is concluded: (1) ZDR, KDP and ρhv can be enlarging gradually as rainfall intensity increasing; ZDR of hail is negative, and KDP of hail is larger than that of heavy rains, but smaller than that of torrential rains; ρhvof both light and moderate rainfall exceed 090, but the mean value of hails is only 0804 (2) The four radar rainfall estimation equations all overvalue the light and moderate rains and underestimate heavy rains, but the measuring errors of three rainfall estimation equations containing ZDR and KDP are smaller than that of the 〖WTBX〗I〖KG-*8〗〖CD*2〗〖KG-*8〗Z〖WTBZ〗H equation. As for short term rainstorms, the effectiveness of these three equations has obvious improvement, and the best is the I〖CD*2〗KDP〖CD*2〗〖KG-*8〗ZDR equation. (3) The case analysis of hydrometeors identification indicates that the estimate of hydrometeors (such as hail) is more direct and effective by using dual polarization products, which can reveal the hydrometeor phase state more clearly and judge the height of the 0 ℃ layer bright zone.
2014, 42(3):373-377.
Abstract:
Analytical geometry is used for analyzing and proofing main calibration methods of L Band Wind Finding Radar systems, such as the zero calibration of antenna azimuth, the perpendicular calibration of the optical axis and the mechanical elevation axis, the parallel calibration of the optical axis and the sea level, the consistent calibration of the optical axis and the electrical axis, etc. The theoretical analysis of these calibration methods is made. Based on the calibration methods and the analytical results, the keys of calibration implementation of L Band Wind Finding Radar systems are summarized. Some shortcomings are analyzed, and the corresponding improvement methods are given. The theoretical analysis may lay a good theoretical basis for technicians to grasp radar calibration methods. The implementation keys may help reduce calibration errors and ensure the reliability of radar detection. The improvement methods can be used as technical references for improving calibration implementation and system device maintenance.
Analytical geometry is used for analyzing and proofing main calibration methods of L Band Wind Finding Radar systems, such as the zero calibration of antenna azimuth, the perpendicular calibration of the optical axis and the mechanical elevation axis, the parallel calibration of the optical axis and the sea level, the consistent calibration of the optical axis and the electrical axis, etc. The theoretical analysis of these calibration methods is made. Based on the calibration methods and the analytical results, the keys of calibration implementation of L Band Wind Finding Radar systems are summarized. Some shortcomings are analyzed, and the corresponding improvement methods are given. The theoretical analysis may lay a good theoretical basis for technicians to grasp radar calibration methods. The implementation keys may help reduce calibration errors and ensure the reliability of radar detection. The improvement methods can be used as technical references for improving calibration implementation and system device maintenance.
2014, 42(3):378-381.
Abstract:
Dual polarization weather radar mainly has two operating modes: simultaneous transmission and reception; horizontal/vertical alternate transmission and simultaneous reception. Comparison is conducted on the advantages and disadvantages of the two modes in aspects of the accuracy of spectral moment estimation, the measurement range for velocity, ground clutter suppression, signal to noise ratio, and so on, and the depolarization phenomenon in weather radar as well as its effect on differential reflectivity products are analyzed. Taking linear depolarization ratio as an example, the polarization isolation degree in dual polarization weather radar is discussed. Theoretical analysis and computation indicates that accurate polarimetric measurement demands a strict polarization isolation degree.
Dual polarization weather radar mainly has two operating modes: simultaneous transmission and reception; horizontal/vertical alternate transmission and simultaneous reception. Comparison is conducted on the advantages and disadvantages of the two modes in aspects of the accuracy of spectral moment estimation, the measurement range for velocity, ground clutter suppression, signal to noise ratio, and so on, and the depolarization phenomenon in weather radar as well as its effect on differential reflectivity products are analyzed. Taking linear depolarization ratio as an example, the polarization isolation degree in dual polarization weather radar is discussed. Theoretical analysis and computation indicates that accurate polarimetric measurement demands a strict polarization isolation degree.
2014, 42(3):382-390.
Abstract:
Based on the daily precipitation data from 196 to 2011 in China, a comparative analysis is made of the changes of the numbers of moderate rain days and heavy rain days, strong precipitation, and extreme precipitation under different station networks to assess the representativeness of different station networks for extreme precipitation events. The results show that the monitoring precision in time and spatial distribution of the station networks for extreme precipitation events changes are in the following order: the basic & reference station network, basic networks, reference station network, and GCOS station network. The influences of spatial distributions of the GCOS station network and the reference station network on the precipitation index differ from the standard station network greatly. The space distributions of various indexes under the basic & reference and basic station networks are the closest to that of the standard station network, but the monitoring precisions in the northern Southwest China, the eastern and central Northeast China, and some areas of the northern Yangtze River are still unsatisfactory.
Based on the daily precipitation data from 196 to 2011 in China, a comparative analysis is made of the changes of the numbers of moderate rain days and heavy rain days, strong precipitation, and extreme precipitation under different station networks to assess the representativeness of different station networks for extreme precipitation events. The results show that the monitoring precision in time and spatial distribution of the station networks for extreme precipitation events changes are in the following order: the basic & reference station network, basic networks, reference station network, and GCOS station network. The influences of spatial distributions of the GCOS station network and the reference station network on the precipitation index differ from the standard station network greatly. The space distributions of various indexes under the basic & reference and basic station networks are the closest to that of the standard station network, but the monitoring precisions in the northern Southwest China, the eastern and central Northeast China, and some areas of the northern Yangtze River are still unsatisfactory.
2014, 42(3):391-396.
Abstract:
A method of Cloud Motion Wind (CMW) vector prediction is presented, which is based on the Scale Invariant Feature Transform (SIFT) and achieves the CMW vector results by means of calculating and matching scale invariant feature points. Comparison is conducted between traditional Maximum Cross Correlation (MCC) and SIFTS methods by using the experimental data of cloud pictures from the FY 2 satellite. The comparison result indicates that the SIFT method can achieve more valid cloud vectors under different types of clouds and have more reasonable distribution.
A method of Cloud Motion Wind (CMW) vector prediction is presented, which is based on the Scale Invariant Feature Transform (SIFT) and achieves the CMW vector results by means of calculating and matching scale invariant feature points. Comparison is conducted between traditional Maximum Cross Correlation (MCC) and SIFTS methods by using the experimental data of cloud pictures from the FY 2 satellite. The comparison result indicates that the SIFT method can achieve more valid cloud vectors under different types of clouds and have more reasonable distribution.
2014, 42(3):397-401.
Abstract:
As one of important approaches to obtain the ozone concentration profile from the surface to the upper stratosphere, ozone sondes need to be tested before launching to evaluate its performance and to make sure that high quality observational data can be obtained during the flight. The detailed information about the ground based test system for electrochemical concentration cells of ozone sondes is described. The system is composed of the test unit, data collecting module, and software used for the data processing, which is used to test the background current and response time of the electrochemical concentration cells. The test unit can provide air containing different ozone concentrations deployed to test the detecting performance of a cell. The test results are transferred to a computer by the data collecting module. The software can store and process the collected data as well as extract the background current and response time automatically. The application results show that the test system has high accuracy and stable performance and thus can be used for the ground based ozone sonde check for conventional observations in China in future.
As one of important approaches to obtain the ozone concentration profile from the surface to the upper stratosphere, ozone sondes need to be tested before launching to evaluate its performance and to make sure that high quality observational data can be obtained during the flight. The detailed information about the ground based test system for electrochemical concentration cells of ozone sondes is described. The system is composed of the test unit, data collecting module, and software used for the data processing, which is used to test the background current and response time of the electrochemical concentration cells. The test unit can provide air containing different ozone concentrations deployed to test the detecting performance of a cell. The test results are transferred to a computer by the data collecting module. The software can store and process the collected data as well as extract the background current and response time automatically. The application results show that the test system has high accuracy and stable performance and thus can be used for the ground based ozone sonde check for conventional observations in China in future.
2014, 42(3):402-408.
Abstract:
With the development of intelligent meteorological observation, a large number of new equipment and new tasks are added to observation operation, resulting in the increasing complication of observed data display and equipment condition monitoring. A platform is proposed for displaying and monitoring of surface meteorological observation, which adopts Dundas, Grid, 3ds MAX modeling, and system structure diagram technology to display data and monitor equipment. This platform can greatly improve the observation efficiency and reduce the workload of observers.
With the development of intelligent meteorological observation, a large number of new equipment and new tasks are added to observation operation, resulting in the increasing complication of observed data display and equipment condition monitoring. A platform is proposed for displaying and monitoring of surface meteorological observation, which adopts Dundas, Grid, 3ds MAX modeling, and system structure diagram technology to display data and monitor equipment. This platform can greatly improve the observation efficiency and reduce the workload of observers.
2014, 42(3):409-412.
Abstract:
Currently, most testing equipments in the provincial level meteorological metrological laboratories are equipped with the programmable interface of RS232 In order to improve the calibration efficiency of the temperature sensors, the serial communication protocol of such devices as SR253 thermostats, high accuracy thermometers and three kinds of scanning collectors in common use and so on are discussed. An automatic calibration system for temperature sensors is designed in combination with the database of SQL Server 2000 based on the VB60 development platform. The experimental results show that the automatic verification system is reliable and easy to operate with high commonality, which improves the verification efficiency significantly, avoids the arbitrary factors which may be caused by manual testing, and is able to provide high quality calibration.
Currently, most testing equipments in the provincial level meteorological metrological laboratories are equipped with the programmable interface of RS232 In order to improve the calibration efficiency of the temperature sensors, the serial communication protocol of such devices as SR253 thermostats, high accuracy thermometers and three kinds of scanning collectors in common use and so on are discussed. An automatic calibration system for temperature sensors is designed in combination with the database of SQL Server 2000 based on the VB60 development platform. The experimental results show that the automatic verification system is reliable and easy to operate with high commonality, which improves the verification efficiency significantly, avoids the arbitrary factors which may be caused by manual testing, and is able to provide high quality calibration.
2014, 42(3):413-416.
Abstract:
Aiming at the failure and maintenance of DT50 data collectors from CAWS600 B automatic weather stations in recent years in Shandong Province，four common faults of DT50 data collectors are classified and discussed. While repairing DT50 in a laboratory, DT50 communicates with a computer by the simplified approach, using a communication line to connect DT50 and the computer directly. The troubleshooting method of abnormal detection data failure is to replace the channel chip (CD4052). Generally, the communication failure recovery method is to replace the communication driver chip (SP312). The built in program runaway failure can be solved by rewriting the built in program. When the internal time of DT50 goes wrong, the battery in the following circuit board should be replaced by a new one. The matters needing attention in troubleshooting are also discussed. Through the four troubleshooting methods, the most failures of DT50 can be repaired successfully, except small tolerance data failure.
Aiming at the failure and maintenance of DT50 data collectors from CAWS600 B automatic weather stations in recent years in Shandong Province，four common faults of DT50 data collectors are classified and discussed. While repairing DT50 in a laboratory, DT50 communicates with a computer by the simplified approach, using a communication line to connect DT50 and the computer directly. The troubleshooting method of abnormal detection data failure is to replace the channel chip (CD4052). Generally, the communication failure recovery method is to replace the communication driver chip (SP312). The built in program runaway failure can be solved by rewriting the built in program. When the internal time of DT50 goes wrong, the battery in the following circuit board should be replaced by a new one. The matters needing attention in troubleshooting are also discussed. Through the four troubleshooting methods, the most failures of DT50 can be repaired successfully, except small tolerance data failure.
2014, 42(3):417-422.
Abstract:
Affected by satellite channel transmission errors, interference signals and rain attenuation, the files broadcasted by CMACast might be lost or received mistakenly at the receiving stations, resulting in an incomplete collection of broadcasting data, which further impacts the forecasting and other meteorological service. To build a data center and provide downloading service through the ground wideband network is an effective solution to cover the shortage of the satellite network. The data downloading client implements data downloading process to better meet the demands of the provincial level downloading service, in which a two stage downloading mechanism is designed and a flexible configurable mode is adopted. The client adopts such technologies as multi level parallel processing and priority based dynamic scheduling in the program. The downloading client has been deployed on the provincial telecommunication systems and received practical benefits in daily meteorological service. The mechanism and implementation of the downloading service are introduced in detail.
Affected by satellite channel transmission errors, interference signals and rain attenuation, the files broadcasted by CMACast might be lost or received mistakenly at the receiving stations, resulting in an incomplete collection of broadcasting data, which further impacts the forecasting and other meteorological service. To build a data center and provide downloading service through the ground wideband network is an effective solution to cover the shortage of the satellite network. The data downloading client implements data downloading process to better meet the demands of the provincial level downloading service, in which a two stage downloading mechanism is designed and a flexible configurable mode is adopted. The client adopts such technologies as multi level parallel processing and priority based dynamic scheduling in the program. The downloading client has been deployed on the provincial telecommunication systems and received practical benefits in daily meteorological service. The mechanism and implementation of the downloading service are introduced in detail.
2014, 42(3):423-427.
Abstract:
In order to optimize the management of meteorological equipment and the safeguard ability and strengthen the emergency stockpile management of meteorological equipment, a meteorological equipment life cycle tracking system platform is presented, in combination with RFID (Radio Frequency Identification) technology, hand held devices, and Web development. This system combines the needs of meteorological equipment allocation and warehousing in China, to achieve the integration and harmonization of operational management of the national meteorological equipment and facilitate the inter regional efficient use of meteorological equipment. By tracking meteorological equipment status information (including storage information, basic device information, service status, etc.), it can provide detailed references to the equipment management personnel. Combined with the research results of meteorological equipment encoding rules, a unique identification is given for each set of meteorological equipment, which provides practical reference data for life cycle prediction of meteorological equipment.
In order to optimize the management of meteorological equipment and the safeguard ability and strengthen the emergency stockpile management of meteorological equipment, a meteorological equipment life cycle tracking system platform is presented, in combination with RFID (Radio Frequency Identification) technology, hand held devices, and Web development. This system combines the needs of meteorological equipment allocation and warehousing in China, to achieve the integration and harmonization of operational management of the national meteorological equipment and facilitate the inter regional efficient use of meteorological equipment. By tracking meteorological equipment status information (including storage information, basic device information, service status, etc.), it can provide detailed references to the equipment management personnel. Combined with the research results of meteorological equipment encoding rules, a unique identification is given for each set of meteorological equipment, which provides practical reference data for life cycle prediction of meteorological equipment.
2014, 42(3):428-433.
Abstract:
Weather conditions have become a key element of driving safety, so the precision and individuation of meteorological information service for driving become the new urgent demand of operation meteorological service. To meet the demand, a system model of driving weather service is put forward. It is based on the customized route on the computer Google Maps and the short message service (SMS) received at mobile phone clients. The design is based on the data processing mode: data information knowledge products. The objective analysis of the gridded meteorological field information is used as the meteorological service foundation, and the route analysis is based on JSON, in which the user customized route is analyzed by means of Google Maps API. The PrimeFaces Decoder and the distribution function filtering methods are used to obtain the geographic coordinates of the route. The customized meteorological information service is provided via SMS to users. The car driving weather service system based on this model has been put into trial operation, which is a new attempt on SMS meteorological service.
Weather conditions have become a key element of driving safety, so the precision and individuation of meteorological information service for driving become the new urgent demand of operation meteorological service. To meet the demand, a system model of driving weather service is put forward. It is based on the customized route on the computer Google Maps and the short message service (SMS) received at mobile phone clients. The design is based on the data processing mode: data information knowledge products. The objective analysis of the gridded meteorological field information is used as the meteorological service foundation, and the route analysis is based on JSON, in which the user customized route is analyzed by means of Google Maps API. The PrimeFaces Decoder and the distribution function filtering methods are used to obtain the geographic coordinates of the route. The customized meteorological information service is provided via SMS to users. The car driving weather service system based on this model has been put into trial operation, which is a new attempt on SMS meteorological service.
2014, 42(3):434-442.
Abstract:
The effects of varying intensity on the simulation of the merging of binary tropical cyclone (TC) Lionrock (2010) and Namtheum (2010) are studied using the HWRF (Hurricane Weather Research and Forecast System) mesoscale model. It is shown that the model reproduces well the intensity, track, and merging features of two TCs. Detailed analyses of the control experiment show that the intensity of Lionrock was stronger than that of Namtheum and attracted Namtheum significantly; a connected relatively high energy and water vapor channel, which linked the circulations of Lionrock and Namtheum, existed in the west of the two TCs. In the merging process of two TCs, Lionrock destroyed Namtheums structure. The rainbands of Namtheum merged with those of Lionrock. Sensitive experiments indicate that the intensity of Lionrock weakens, but the intensify of Namtheum strengthens; the two TCs still rotates and attract each other, but the merging direction is inversed.
The effects of varying intensity on the simulation of the merging of binary tropical cyclone (TC) Lionrock (2010) and Namtheum (2010) are studied using the HWRF (Hurricane Weather Research and Forecast System) mesoscale model. It is shown that the model reproduces well the intensity, track, and merging features of two TCs. Detailed analyses of the control experiment show that the intensity of Lionrock was stronger than that of Namtheum and attracted Namtheum significantly; a connected relatively high energy and water vapor channel, which linked the circulations of Lionrock and Namtheum, existed in the west of the two TCs. In the merging process of two TCs, Lionrock destroyed Namtheums structure. The rainbands of Namtheum merged with those of Lionrock. Sensitive experiments indicate that the intensity of Lionrock weakens, but the intensify of Namtheum strengthens; the two TCs still rotates and attract each other, but the merging direction is inversed.
2014, 42(3):443-450.
Abstract:
Based on the observed meteorological data of Enshi Station from 2008 to 2011, numerical forecast products, and superior station guidance, by means of the combined method of M (numerical model forecast), E (learning experience of weather), D (diagnostic analysis), the predictors with atmospheric physics significance are designed from the aspect of the influencing factors of temperature changes, such as the atmospheric stability, temperature advection, water vapor conditions, etc.; or a combination of factors according to the needs is considered, and the superior guidance products are used as predictors directly. Using the conventional statistical forecast method (stepwise regression), taking high and low temperature as predictands, the local temperature prediction model is established considering the direct factors influencing the atmospheric temperature. The local temperature MOS forecast model is established after sky condition classification, and the numerical forecast products are selected corresponding to the appearing time of high and low temperature, which is of significance to the quality improvement of local temperature forecasting. During the model building, the combined method and reprocessed numerical forecast factors are used, and the influence of weather variation on air temperature is considered, so the application and interpretation capability of numerical forecast products is enhanced. The comprehensive MOS forecasting referring to the objective numerical model products and superior guidance products is an attempt to improve the local weather forecast accuracy effectively. Test results also show that the local temperature MOS forecast method performed well, with the effectiveness significantly better than guidance forecasting.
Based on the observed meteorological data of Enshi Station from 2008 to 2011, numerical forecast products, and superior station guidance, by means of the combined method of M (numerical model forecast), E (learning experience of weather), D (diagnostic analysis), the predictors with atmospheric physics significance are designed from the aspect of the influencing factors of temperature changes, such as the atmospheric stability, temperature advection, water vapor conditions, etc.; or a combination of factors according to the needs is considered, and the superior guidance products are used as predictors directly. Using the conventional statistical forecast method (stepwise regression), taking high and low temperature as predictands, the local temperature prediction model is established considering the direct factors influencing the atmospheric temperature. The local temperature MOS forecast model is established after sky condition classification, and the numerical forecast products are selected corresponding to the appearing time of high and low temperature, which is of significance to the quality improvement of local temperature forecasting. During the model building, the combined method and reprocessed numerical forecast factors are used, and the influence of weather variation on air temperature is considered, so the application and interpretation capability of numerical forecast products is enhanced. The comprehensive MOS forecasting referring to the objective numerical model products and superior guidance products is an attempt to improve the local weather forecast accuracy effectively. Test results also show that the local temperature MOS forecast method performed well, with the effectiveness significantly better than guidance forecasting.
2014, 42(3):451-459.
Abstract:
Using the four dimensional data assimilation method, the wind profile radar and wind tower data are applied to the WRF model, and the comparison of the prediction effects before and after data assimilation of the surface wind field shows that wind speed forecasting is improved obviously after using the wind profile radar and wind tower data model, and the wind direction prediction is also improved to a certain extent; after the data assimilation, the model prediction within 49 hours of the surface wind field is also improved obviously, but there is no obvious variation in the effectiveness of assimilation data in the surface wind field prediction before and after data assimilation with the increased model lead time after 49 hours. By analyzing the errors of the WRF model in wind speed prediction before and after data assimilation, it is shown that the contribution of profile radar data is much greater than that of wind tower data.
Using the four dimensional data assimilation method, the wind profile radar and wind tower data are applied to the WRF model, and the comparison of the prediction effects before and after data assimilation of the surface wind field shows that wind speed forecasting is improved obviously after using the wind profile radar and wind tower data model, and the wind direction prediction is also improved to a certain extent; after the data assimilation, the model prediction within 49 hours of the surface wind field is also improved obviously, but there is no obvious variation in the effectiveness of assimilation data in the surface wind field prediction before and after data assimilation with the increased model lead time after 49 hours. By analyzing the errors of the WRF model in wind speed prediction before and after data assimilation, it is shown that the contribution of profile radar data is much greater than that of wind tower data.
2014, 42(3):460-465.
Abstract:
Based on the characteristic analysis of satellite images during short time rainstorm in Hubei Province, by using the real time satellite data and collecting the characteristic parameters of the images related to the short time rainstorm, a probabilistic short time rainstorm forecasting method is presented, which is regionalized with a lead time of 0 to 6 hour, in combination with NCEP numerical forecasting products. The results show that the selected characteristic parameters can reflect the different characteristics of short time rainstorms, and the calculating method is reasonable and plays a certain guidance role in short time rainstorm forecasting, but it should be improved in the aspects of false and miss forecasting rates.
Based on the characteristic analysis of satellite images during short time rainstorm in Hubei Province, by using the real time satellite data and collecting the characteristic parameters of the images related to the short time rainstorm, a probabilistic short time rainstorm forecasting method is presented, which is regionalized with a lead time of 0 to 6 hour, in combination with NCEP numerical forecasting products. The results show that the selected characteristic parameters can reflect the different characteristics of short time rainstorms, and the calculating method is reasonable and plays a certain guidance role in short time rainstorm forecasting, but it should be improved in the aspects of false and miss forecasting rates.
2014, 42(3):466-473.
Abstract:
The spatial and temporal characteristics of water vapor from 500 hPa to 200 hPa level in winter and summer are analyzed by using the monthly mean radiosonde data at various levels of 16 stations over the mid eastern Tibet Plateau from 1979 to 2008 The results indicate: (1) The spatial distribution of winter and summer water vapor over the mid eastern Tibet Plateau shows obvious northwest southeast direction. The inter annual fluctuation of vapor over the southern plateau is bigger in winter and summer, relatively stable in the northern plateau. Water vapor changes identically in general in summer and winter, and there also exists north to south reverse phase regional anomaly change in summer, while there is east to west reverse phase change in winter. (2) The water vapor in summer shows a weak rising trend over time generally, negative during 1979-1995 and positive during 1996-2005, with the breakpoints in 1997 and 2006; the water vapor in winter as a whole shows a slightly decreasing trend, negative during 1979-1984, stably during 1985-2004 with the breakpoints in 1985 and 2005 In general, there is a positive trend in vapor over the western plateau and a negative trend over the eastern plateau.
The spatial and temporal characteristics of water vapor from 500 hPa to 200 hPa level in winter and summer are analyzed by using the monthly mean radiosonde data at various levels of 16 stations over the mid eastern Tibet Plateau from 1979 to 2008 The results indicate: (1) The spatial distribution of winter and summer water vapor over the mid eastern Tibet Plateau shows obvious northwest southeast direction. The inter annual fluctuation of vapor over the southern plateau is bigger in winter and summer, relatively stable in the northern plateau. Water vapor changes identically in general in summer and winter, and there also exists north to south reverse phase regional anomaly change in summer, while there is east to west reverse phase change in winter. (2) The water vapor in summer shows a weak rising trend over time generally, negative during 1979-1995 and positive during 1996-2005, with the breakpoints in 1997 and 2006; the water vapor in winter as a whole shows a slightly decreasing trend, negative during 1979-1984, stably during 1985-2004 with the breakpoints in 1985 and 2005 In general, there is a positive trend in vapor over the western plateau and a negative trend over the eastern plateau.
2014, 42(3):474-481.
Abstract:
Using the daily temperature data from 63 stations from 1971 to 2011 over Zhejiang Province, combining with the phenology data, statistical calculations and comparative analysis are conducted. The results show that the seasons often start later by the method of pentad temperature and earlier or later with the methods of meteorology and climatology; the abnormal season start dates caused by different methods exhibit different characteristics in various regions. The main reasons for the abnormal season start dates are analyzed, and the results indicate that abnormal cases occur mainly when the temperature fluctuation of several days leads to the unsatisfied conditions of season change, but the lasting time of the fluctuations is not long generally, mainly in 3 to 5 days, and the fluctuation range is not great. So considering fully the advantages and disadvantages of various methods and the influence of temperature fluctuation, a method is presented, which is reasonable relatively and applicable to Zhejiang Province and can solve the problems of these methods. The provincial average start dates of seasons are 16 March, 29 May, 30 September, and 8 December. The frequency of seasons starting earlier or later reduced obviously, compared with other methods，and the result is more in line with the phenology in each region.
Using the daily temperature data from 63 stations from 1971 to 2011 over Zhejiang Province, combining with the phenology data, statistical calculations and comparative analysis are conducted. The results show that the seasons often start later by the method of pentad temperature and earlier or later with the methods of meteorology and climatology; the abnormal season start dates caused by different methods exhibit different characteristics in various regions. The main reasons for the abnormal season start dates are analyzed, and the results indicate that abnormal cases occur mainly when the temperature fluctuation of several days leads to the unsatisfied conditions of season change, but the lasting time of the fluctuations is not long generally, mainly in 3 to 5 days, and the fluctuation range is not great. So considering fully the advantages and disadvantages of various methods and the influence of temperature fluctuation, a method is presented, which is reasonable relatively and applicable to Zhejiang Province and can solve the problems of these methods. The provincial average start dates of seasons are 16 March, 29 May, 30 September, and 8 December. The frequency of seasons starting earlier or later reduced obviously, compared with other methods，and the result is more in line with the phenology in each region.
2014, 42(3):482-487.
Abstract:
Using the hourly precipitation data from April to October, 1999 to 2011 in Shandong Province, the threshold values of short term extremely heavy precipitation in Shandong province are defined and calculated with three methods (sorting, normal distribution transformation, and square root transformation). The results show that the thresholds gotten with different methods are significantly different. The threshold values calculated by the sorting method are close to the actual distribution, so the threshold values in the five parts of Shandong Province are defined. The threshold values in the southeast, central, and the northwest parts of Shandong Province are bigger, but those in the southwest and peninsula parts of Shandong Province are lower, especially that in the southwest is the lowest. Short term extremely heavy precipitations appear frequently in the northwestern, southwestern, southeastern, and central Shandong Province, as well as the southern Shandong Peninsula, but rarely occur in the northern Peninsula. Short term extremely heavy precipitations are not necessarily related to the annual mean precipitation and often happen accidentally. The right measures should be taken for short term extreme heavy precipitations, especially in July and August.
Using the hourly precipitation data from April to October, 1999 to 2011 in Shandong Province, the threshold values of short term extremely heavy precipitation in Shandong province are defined and calculated with three methods (sorting, normal distribution transformation, and square root transformation). The results show that the thresholds gotten with different methods are significantly different. The threshold values calculated by the sorting method are close to the actual distribution, so the threshold values in the five parts of Shandong Province are defined. The threshold values in the southeast, central, and the northwest parts of Shandong Province are bigger, but those in the southwest and peninsula parts of Shandong Province are lower, especially that in the southwest is the lowest. Short term extremely heavy precipitations appear frequently in the northwestern, southwestern, southeastern, and central Shandong Province, as well as the southern Shandong Peninsula, but rarely occur in the northern Peninsula. Short term extremely heavy precipitations are not necessarily related to the annual mean precipitation and often happen accidentally. The right measures should be taken for short term extreme heavy precipitations, especially in July and August.
2014, 42(3):488-495.
Abstract:
Unsuccessful forecasting for two snowfall processes in Beijing in 2011 is analyzed by using a variety of high spatial temporal resolution observation data, NCEP1°×1°analysis data, and conventional observation data. The result shows: (1) On 29 November 2011, one of the most important reasons that there was no snow in Beijing is that the east winds in Beijing were dry and cold in a deep layer, and the boundary layer moisture condition was unfavorable. The cold air moved southward, leading to a filling pressure trough in the lower troposphere, which is another important reason for the fault prediction. (2) In the process of snowfall on 2 December 2011, the front and 925 hPa shear line provided dynamic condition for uplifting boundary layer water vapor convergence, and the lower troposphere water vapor transmission provided the moisture condition for snow. (3) Comparative analysis shows that more attention should be paid to water vapor change in the boundary layer in snow forecasting in Beijing. It hardly snows even if there is obviously favorable weather pattern but poor water vapor condition in the boundary layer; it probably snows if there is good moisture condition and convergence in the boundary layer, even if there were no favorable weather systems in the middle troposphere.
Unsuccessful forecasting for two snowfall processes in Beijing in 2011 is analyzed by using a variety of high spatial temporal resolution observation data, NCEP1°×1°analysis data, and conventional observation data. The result shows: (1) On 29 November 2011, one of the most important reasons that there was no snow in Beijing is that the east winds in Beijing were dry and cold in a deep layer, and the boundary layer moisture condition was unfavorable. The cold air moved southward, leading to a filling pressure trough in the lower troposphere, which is another important reason for the fault prediction. (2) In the process of snowfall on 2 December 2011, the front and 925 hPa shear line provided dynamic condition for uplifting boundary layer water vapor convergence, and the lower troposphere water vapor transmission provided the moisture condition for snow. (3) Comparative analysis shows that more attention should be paid to water vapor change in the boundary layer in snow forecasting in Beijing. It hardly snows even if there is obviously favorable weather pattern but poor water vapor condition in the boundary layer; it probably snows if there is good moisture condition and convergence in the boundary layer, even if there were no favorable weather systems in the middle troposphere.
2014, 42(3):496-502.
Abstract:
In 2011, an observational experiment was conducted on a large water body in Zhejiang Province with automatic observing stations deployed both upwind and downwind at the specified distances to observe temperature synchronously to study the quantitative regularities of the influence of water body on temperature. The results show that a water body has cooling effect in daytime and warming effect in nighttime on surrounding land, the closer the land to the water, the more significant the effect is; the warming effect in nighttime is more significant than the cooling effect in daytime, and the cooling effect in daytime is more significant from March to May than that from January to February; in a day, the cooling effect reaches its maximum at noon; a water area of 2 km2 has an obvious effect on the temperature observation within 100 m downwind, and much less obvious beyond 100 m. The study made a good attempt to quantify the scope and magnitude of the influence of water body on temperature measurements and provides a basis for the scientific location selection of meteorological stations.
In 2011, an observational experiment was conducted on a large water body in Zhejiang Province with automatic observing stations deployed both upwind and downwind at the specified distances to observe temperature synchronously to study the quantitative regularities of the influence of water body on temperature. The results show that a water body has cooling effect in daytime and warming effect in nighttime on surrounding land, the closer the land to the water, the more significant the effect is; the warming effect in nighttime is more significant than the cooling effect in daytime, and the cooling effect in daytime is more significant from March to May than that from January to February; in a day, the cooling effect reaches its maximum at noon; a water area of 2 km2 has an obvious effect on the temperature observation within 100 m downwind, and much less obvious beyond 100 m. The study made a good attempt to quantify the scope and magnitude of the influence of water body on temperature measurements and provides a basis for the scientific location selection of meteorological stations.
23 Physical Mechanisms of a Heavy Fog Process on Shanghai Nanjing Expressway in Early Winter of 2009
2014, 42(3):503-510.
Abstract:
Based on the data from Auto Meteorological Monitoring Workstations (AMW) of Shanghai Nanjing Expressway and NCEP/NCAR 1°×1° grid reanalysis data, the evolution characteristics of visibility, the relationship between visibility and meteorological elements, and the formation mechanisms of a heavy fog process which occurred on 1 and 2 December 2009 on the Shanghai Nanjing Expressway are investigated. The results indicate that there was nonlinear relationship between atmospheric visibility and meteorological factors. Visibility and relative humidity exhibited obvious exponential decay relationship. The relationship between visibility, wind speed, and temperature was more complex. The synoptic weather analysis indicates that the inversion layer and weak wind conditions near the ground provided by a high/low altitude circulation with warm high ridge and a transformed surface cold high pressure system were contributed to the formation of the fog. Moisture supply and gathering in the lower layers were ensured by the easterly airflow and the thermal inversion layer. Analysis of the thermal and dynamic factors over the fog zone confirmed the stability of atmospheric stratification of the fog zone.
Based on the data from Auto Meteorological Monitoring Workstations (AMW) of Shanghai Nanjing Expressway and NCEP/NCAR 1°×1° grid reanalysis data, the evolution characteristics of visibility, the relationship between visibility and meteorological elements, and the formation mechanisms of a heavy fog process which occurred on 1 and 2 December 2009 on the Shanghai Nanjing Expressway are investigated. The results indicate that there was nonlinear relationship between atmospheric visibility and meteorological factors. Visibility and relative humidity exhibited obvious exponential decay relationship. The relationship between visibility, wind speed, and temperature was more complex. The synoptic weather analysis indicates that the inversion layer and weak wind conditions near the ground provided by a high/low altitude circulation with warm high ridge and a transformed surface cold high pressure system were contributed to the formation of the fog. Moisture supply and gathering in the lower layers were ensured by the easterly airflow and the thermal inversion layer. Analysis of the thermal and dynamic factors over the fog zone confirmed the stability of atmospheric stratification of the fog zone.
2014, 42(3):511-515.
Abstract:
In order to improve the safety of weather modification operation, a system is established to generate warning products and recommended products for artificial precipitation enhancement with the radar echo extrapolation products of TREC, TITAN technology, and safe shooting area data. The system can make warning products by means of the relationship between 30 min and 60 min extrapolation radar products and maximum shooting distances of cannons and rockets, calculate the shooting angles by means of the relationship between current radar products and locations of weather modification operation, and make real time and objective recommended products through screening by means of the safe shot area technology, so to achieve safe and efficient operation and to avoid making mistakes.
In order to improve the safety of weather modification operation, a system is established to generate warning products and recommended products for artificial precipitation enhancement with the radar echo extrapolation products of TREC, TITAN technology, and safe shooting area data. The system can make warning products by means of the relationship between 30 min and 60 min extrapolation radar products and maximum shooting distances of cannons and rockets, calculate the shooting angles by means of the relationship between current radar products and locations of weather modification operation, and make real time and objective recommended products through screening by means of the safe shot area technology, so to achieve safe and efficient operation and to avoid making mistakes.
2014, 42(3):516-523.
Abstract:
In order to make full use of climate resources, pursue better benefits while avoiding disadvantages, plan and develop the apple industry in Shaanxi reasonably, and promote the optimization of apple planting layout and the healthful and sustainable production at county level, the apple drought indexes at each growth stages for 4 apple planting counties, which are on behalf of the different climate types, are calculated and analyzed, in combination with the actual geographical and climate features of apple growing areas in Shaanxi Province. The apple drought risk regionalization is conducted for each growth stage and 4 apple planting counties. The results show that the period from apple budding to young fruit appearing is the time in which apple trees are most likely attacked by droughts in Shaanxi in the whole growth period, and the fruit enlargement period is the second, then the period from coloring to mature and the wintering period; in the whole growth period, apple drought in Yan’an is the most serious, then in the northeastern and northwestern Weihe, and apple drought in Guanzhong is the least serious relatively. The results can be used as references for anti drought service at different apple growth stages in different apple growing areas in Shaanxi and for decision making in disaster prevention and mitigation of apple industry.
In order to make full use of climate resources, pursue better benefits while avoiding disadvantages, plan and develop the apple industry in Shaanxi reasonably, and promote the optimization of apple planting layout and the healthful and sustainable production at county level, the apple drought indexes at each growth stages for 4 apple planting counties, which are on behalf of the different climate types, are calculated and analyzed, in combination with the actual geographical and climate features of apple growing areas in Shaanxi Province. The apple drought risk regionalization is conducted for each growth stage and 4 apple planting counties. The results show that the period from apple budding to young fruit appearing is the time in which apple trees are most likely attacked by droughts in Shaanxi in the whole growth period, and the fruit enlargement period is the second, then the period from coloring to mature and the wintering period; in the whole growth period, apple drought in Yan’an is the most serious, then in the northeastern and northwestern Weihe, and apple drought in Guanzhong is the least serious relatively. The results can be used as references for anti drought service at different apple growth stages in different apple growing areas in Shaanxi and for decision making in disaster prevention and mitigation of apple industry.
2014, 42(3):524-529.
Abstract:
Based on the analysis of tropical cyclones in six national basic stations in the recent 60 years, combining with the data of the lightning location system in the recent 4 years, the temporal and spatial distributions of tropical cyclones, coast gales, and ground lightning flashes influencing the coastal region of the northern Jiangsu are analyzed, and their effects on the wind forms in the region are discussed. Results show: (1) Tropical cyclones influencing the coastal region of the northern Jiangsu are mainly moving northwestward on the ocean and northward after landing, and the tropical cyclones of this kind account for 732 (2) Since 1945, 877% of tropical cyclones brought economic benefits for wind power in this region; 123% of tropical cyclones did not cause losses after adequate defenses; and there was no destructive tropical cyclone. (3) The lightning protection examination of wind driven generators should be strengthened in thunderstorm season (June to August), especially in Yancheng. (4) The extreme wind speed and maximum wind speed with a recurrence period of 50 years comply with the national standards for safe operation for Model Ⅲ/Ⅱwind driven generators.
Based on the analysis of tropical cyclones in six national basic stations in the recent 60 years, combining with the data of the lightning location system in the recent 4 years, the temporal and spatial distributions of tropical cyclones, coast gales, and ground lightning flashes influencing the coastal region of the northern Jiangsu are analyzed, and their effects on the wind forms in the region are discussed. Results show: (1) Tropical cyclones influencing the coastal region of the northern Jiangsu are mainly moving northwestward on the ocean and northward after landing, and the tropical cyclones of this kind account for 732 (2) Since 1945, 877% of tropical cyclones brought economic benefits for wind power in this region; 123% of tropical cyclones did not cause losses after adequate defenses; and there was no destructive tropical cyclone. (3) The lightning protection examination of wind driven generators should be strengthened in thunderstorm season (June to August), especially in Yancheng. (4) The extreme wind speed and maximum wind speed with a recurrence period of 50 years comply with the national standards for safe operation for Model Ⅲ/Ⅱwind driven generators.
2014, 42(3):530-534.
Abstract:
Meteorological service satisfaction analysis plays a very important role in public meteorological service satisfaction evaluation. The principal component analysis and the entropy value method are used to gain two sets of ranking results about the satisfaction with the status quo of meteorological service for 31 provinces and cities in China, based on the assessment survey data of national public meteorological service in 2010 The principal component analysis emphasizes the correlation of variables, and the entropy value method emphasizes the uncertainty of variables; so the two ranking results are combined, under the prerequisite of passing the consistency test, to establish another new ranking result by using the integrated comprehensive evaluation method. A new understanding of the satisfaction of meteorological service in a city is obtained, and suggestions about improving meteorological service satisfaction are provided.
Meteorological service satisfaction analysis plays a very important role in public meteorological service satisfaction evaluation. The principal component analysis and the entropy value method are used to gain two sets of ranking results about the satisfaction with the status quo of meteorological service for 31 provinces and cities in China, based on the assessment survey data of national public meteorological service in 2010 The principal component analysis emphasizes the correlation of variables, and the entropy value method emphasizes the uncertainty of variables; so the two ranking results are combined, under the prerequisite of passing the consistency test, to establish another new ranking result by using the integrated comprehensive evaluation method. A new understanding of the satisfaction of meteorological service in a city is obtained, and suggestions about improving meteorological service satisfaction are provided.
2014, 42(3):535-538.
Abstract:
In January 2013, there were several severe fog haze events occurred in Beijing, with the mean visibility being less than 92 km and the PM25 concentration greater than 800 μg/m3 The causes and features are analyzed. The results indicate that the lasting fog haze weather was caused by the stable stratification, continuous southerly winds, and lower air temperature. According to the service experiences, the measures in forecasting and service are discussed in detail. In forecasting, meteorological agencies should take advantage of their technologies, such as numerical simulation and weather forecasting, to provide accurate fog haze forecasts and visualized products for the government, aiming at the regional distribution features of fog haze weather. In service, meteorological agencies should play their special role to provide tailored service according to the demands of the government, public, and end users timely. Some suggestions on fog haze service are given.
In January 2013, there were several severe fog haze events occurred in Beijing, with the mean visibility being less than 92 km and the PM25 concentration greater than 800 μg/m3 The causes and features are analyzed. The results indicate that the lasting fog haze weather was caused by the stable stratification, continuous southerly winds, and lower air temperature. According to the service experiences, the measures in forecasting and service are discussed in detail. In forecasting, meteorological agencies should take advantage of their technologies, such as numerical simulation and weather forecasting, to provide accurate fog haze forecasts and visualized products for the government, aiming at the regional distribution features of fog haze weather. In service, meteorological agencies should play their special role to provide tailored service according to the demands of the government, public, and end users timely. Some suggestions on fog haze service are given.
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.