Different attenuation correction methods for the X-band dual linear polarimetric radar are analyzed in this paper.The specific differential phase shift KDP is always considered as an effective factor in radar signal a...Different attenuation correction methods for the X-band dual linear polarimetric radar are analyzed in this paper.The specific differential phase shift KDP is always considered as an effective factor in radar signal attenuation correction.However,the values of KDP for light rains are too small,which results in unstable quality and large errors of rainfall estimation.Therefore,radar horizontal reflectivity ZH and specific differential phase shift are combined together in the ZH-KDP method to correct the attenuation error.Based on the similar consideration,a ZH-KDP-R combined technique is also proposed to estimate rainfall（R）.During the development and set-up of the synchronous transmitting and receiving dual polaximetric Doppler weather radar with 3.2 cm wave length,a set of observational data were obtained in the field experiment in Pingliang,Gansu Province in August 2005.Some continuous measurements with 5-12-minute intervals were gained in the time period from 1508 to 2205（Beijing Time）11 August 2005.Using the data,the performance of the combined attenuation correction and rainfall estimation methods is examined.The results indicate that the ZH-KDP combined method is effective and the correction speed meets the requirement of real-time operations.The analysis of the precipitation process shows that the ZH-KDP-R combined technique is more suitable for rainfall estimation than single factor methods such as the KDP-R or Z-R relation,and the estimated results are in good agreement with automatic rain gauge records.As to the Z-R relation,the deviation between the precipitation estimation and the available gauge measurement decreases obviously when the corrected ZH is used,indicating that the radar data quality has been obviously improved after the attenuation correction.展开更多
The Dynamical-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards(STORM973)project conducted coordinated comprehensive field observations of thunderstorms in the Beijing metropolitan regio...The Dynamical-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards(STORM973)project conducted coordinated comprehensive field observations of thunderstorms in the Beijing metropolitan region(BMR)during the warm season from 2014 to 2018.The aim of the project was to understand how dynamical,microphysical and electrical processes interact in severe thunderstorms in the BMR,and how to assimilate lightning data in numerical weather prediction models to improve severe thunderstorm forecasts.The platforms used in the field campaign included the Beijing Lightning Network(BLNET,consisting of 16 stations),2 X-band dual linear polarimetric Doppler radars,and 4 laser raindrop spectrometers.The collaboration also made use of the China Meteorological Administration’s mesoscale meteorological observation network in the Beijing-Tianjin-Hebei region.Although diverse thunderstorm types were documented,it was found that squall lines and multicell storms were the two major categories of severe thunderstorms with frequent lightning activity and extreme rainfall or unexpected local short-duration heavy rainfall resulting in inundations in the central urban area,influenced by the terrain and environmental conditions.The flash density maximums were found in eastern Changping District,central and eastern Shunyi District,and the central urban area of Beijing,suggesting that the urban heat island effect has a crucial role in the intensification of thunderstorms over Beijing.In addition,the flash rate associated with super thunderstorms can reach hundreds of flashes per minute in the central city regions.The super(5%of the total),strong(35%),and weak(60%)thunderstorms contributed about 37%,56%,and 7%to the total flashes in the BMR,respectively.Owing to the close connection between lightning activity and the thermodynamic and microphysical characteristics of the thunderstorms,the lightning flash rate can be used as an indicator of severe weather events,such as hail and short-duration heavy rainfall.Lightning data can also be assimilated into numerical weather prediction models to help improve the forecasting of severe convection and precipitation at the cloud-resolved scale,through adjusting or correcting the thermodynamic and microphysical parameters of the model.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos.40975013 and 40975014
文摘Different attenuation correction methods for the X-band dual linear polarimetric radar are analyzed in this paper.The specific differential phase shift KDP is always considered as an effective factor in radar signal attenuation correction.However,the values of KDP for light rains are too small,which results in unstable quality and large errors of rainfall estimation.Therefore,radar horizontal reflectivity ZH and specific differential phase shift are combined together in the ZH-KDP method to correct the attenuation error.Based on the similar consideration,a ZH-KDP-R combined technique is also proposed to estimate rainfall（R）.During the development and set-up of the synchronous transmitting and receiving dual polaximetric Doppler weather radar with 3.2 cm wave length,a set of observational data were obtained in the field experiment in Pingliang,Gansu Province in August 2005.Some continuous measurements with 5-12-minute intervals were gained in the time period from 1508 to 2205（Beijing Time）11 August 2005.Using the data,the performance of the combined attenuation correction and rainfall estimation methods is examined.The results indicate that the ZH-KDP combined method is effective and the correction speed meets the requirement of real-time operations.The analysis of the precipitation process shows that the ZH-KDP-R combined technique is more suitable for rainfall estimation than single factor methods such as the KDP-R or Z-R relation,and the estimated results are in good agreement with automatic rain gauge records.As to the Z-R relation,the deviation between the precipitation estimation and the available gauge measurement decreases obviously when the corrected ZH is used,indicating that the radar data quality has been obviously improved after the attenuation correction.
基金supported by the National Natural Science Foundation of China(Grant Nos.41630425,41671144074)the Key Research Program of Frontier Science,CAS(Grant No.QYZDJ-SSW-DQC007)the National Key Basic Research Program of China(Grant No.2014CB441401)。
文摘The Dynamical-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards(STORM973)project conducted coordinated comprehensive field observations of thunderstorms in the Beijing metropolitan region(BMR)during the warm season from 2014 to 2018.The aim of the project was to understand how dynamical,microphysical and electrical processes interact in severe thunderstorms in the BMR,and how to assimilate lightning data in numerical weather prediction models to improve severe thunderstorm forecasts.The platforms used in the field campaign included the Beijing Lightning Network(BLNET,consisting of 16 stations),2 X-band dual linear polarimetric Doppler radars,and 4 laser raindrop spectrometers.The collaboration also made use of the China Meteorological Administration’s mesoscale meteorological observation network in the Beijing-Tianjin-Hebei region.Although diverse thunderstorm types were documented,it was found that squall lines and multicell storms were the two major categories of severe thunderstorms with frequent lightning activity and extreme rainfall or unexpected local short-duration heavy rainfall resulting in inundations in the central urban area,influenced by the terrain and environmental conditions.The flash density maximums were found in eastern Changping District,central and eastern Shunyi District,and the central urban area of Beijing,suggesting that the urban heat island effect has a crucial role in the intensification of thunderstorms over Beijing.In addition,the flash rate associated with super thunderstorms can reach hundreds of flashes per minute in the central city regions.The super(5%of the total),strong(35%),and weak(60%)thunderstorms contributed about 37%,56%,and 7%to the total flashes in the BMR,respectively.Owing to the close connection between lightning activity and the thermodynamic and microphysical characteristics of the thunderstorms,the lightning flash rate can be used as an indicator of severe weather events,such as hail and short-duration heavy rainfall.Lightning data can also be assimilated into numerical weather prediction models to help improve the forecasting of severe convection and precipitation at the cloud-resolved scale,through adjusting or correcting the thermodynamic and microphysical parameters of the model.
