强降水过程中多普勒雷达特征分析及风场反演
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摘要
秦皇岛市短历时强降水频发,因其东临渤海、北依燕山,地形复杂,所以其强降水具有独特性。本文采用Micaps实时资料、NCAR/NCEP再分析资料、多普勒雷达资料、自动站风场及降水资料,利用WRF模式、雷达回波分析方法、EVAD方法、四维变分方法对秦皇岛市2009年7月6日出现的一次短历时强降水过程进行了细致分析,主要结论如下：
(1)采用WRF模式对本次强降水进行了数值模拟,结果表明：模拟的降水分布与实况较接近,但是模拟的秦皇岛降水偏弱；WRF模式能模拟出低槽在东移过程中在海风加强时段得到加深,其模拟的地面辐合线和水汽辐合中心对强降水具有明显的指示意义,但其对有关物理量的模拟偏弱。WRF模式模拟的降水和有关物理量偏弱,可能是由于初始场资料密度较小,模式在作格点插值时,较小的天气系统有可能被平滑掉。因此,采用常规资料时,WRF模式对中小尺度系统的模拟还有局限性。
(2)对本次强降水过程的多普勒雷达反射率因子特征、垂直风廓线特征及径向速度场特征分析得到：垂直风廓线产品能反映雷达上空大气水汽含量的变化;当中层有干冷空气入侵时,降水强度增大；多普勒雷达径向速度场对强降水的指示作用要早于反射率因子。
(3)运用EVAD方法计算平均大气散度,变分法计算平均大气垂直速度,对此次降水过程动力条件进行分析,通过与降水强弱变化的对比分析,结果表明：该方法能够反映出此次降水过程的动力学特征,当中低层辐合较强,出现强上升运动时,将会引发短历时强降水天气的产生。
(4)通过四维变分方法(每次输入相邻的两个体扫资料)进行风场的反演,对本次短历时强降水进行中小尺度天气系统分析,得到较为真实的中小尺度天气系统状况,强降水发生在“人”字型切变线的暖切变线的前侧,当暖切变线附近出现中-γ闭合气旋性环流时,降水进一步增强。
Short heavy rainfall happens frequently in Qinhuangdao because that it locates in the west of Bohai bay and the north of Yanshan Mountain and has complex terrain. Severe precipitations in the short time have its unique properties. In this paper, utilizing Micaps information, NCAR/ NCEP reanalysis data, Doppler radar, automatic weather station wind and precipitation data, using WRF model, the radar echo analysis, EVAD method, four-dimensional variation method, analyzing a short duration heavy rain occurred in 6 July 2009 in Qinhuangdao City, the main conclusions are as follows:
(1)Using the WRF model simulate the heavy precipitation, the results shows that the simulated distribution of precipitation is close to the observation, but the rainfall in Qinhuangdao simulates weak. WRF model can simulate the trough moving eastward deepening with the strengthening the sea breeze, the simulated surface convergence line and moisture convergence center has obvious implications for heavy rainfall, but relevant physical quantities simulates a little weak. The reasons may be that the initial field data is density, when the model is interpolating, the smaller the weather system may be smoothed out. Therefore, using conventional data simulate small-scale systems in WRF model also has some limitations.
(2)Analyzing the characteristics of Doppler radar reflectivity, vertical wind profile and radial velocity field in the heavy rainfall, the results show that the vertical wind profile radar products can reflect the atmospheric water vapor content changes in higher level; when the dry cold air in middle layer invades, the rainfall intensity increases; the instructions of Doppler radar's radial velocity field on heavy rainfall is earlier than the reflectivity.
(3)Using EVAD method calculate the average atmospheric divergence, using the variation method calculate the average atmospheric vertical velocity, analyzing the dynamic process of the precipitation, the results show that the method can reflect the dynamic characteristics of the precipitation process, the severe convective weather would be brought out when there was strong convergence of low-mid level Jet Stream and with the severe ascending motion.
(4)By four-Dimensional Variation Method (the data of two adjacent volume scan were input once in so-called 4DVM), to run the wind field interpretation, depending on the analysis for the severe precipitation of micro-and meso scale systems in the short time, the situation of micro-and meso-scale weather system can be reflected truly. The heavy rainfall occurred in the "people"(Chinese character) shaped shear line before the warm the shear line side, when the middle-y cyclonic circulation appears near the warn shear line, the precipitation will enhanced further more.
(1)采用WRF模式对本次强降水进行了数值模拟,结果表明：模拟的降水分布与实况较接近,但是模拟的秦皇岛降水偏弱；WRF模式能模拟出低槽在东移过程中在海风加强时段得到加深,其模拟的地面辐合线和水汽辐合中心对强降水具有明显的指示意义,但其对有关物理量的模拟偏弱。WRF模式模拟的降水和有关物理量偏弱,可能是由于初始场资料密度较小,模式在作格点插值时,较小的天气系统有可能被平滑掉。因此,采用常规资料时,WRF模式对中小尺度系统的模拟还有局限性。
(2)对本次强降水过程的多普勒雷达反射率因子特征、垂直风廓线特征及径向速度场特征分析得到：垂直风廓线产品能反映雷达上空大气水汽含量的变化;当中层有干冷空气入侵时,降水强度增大；多普勒雷达径向速度场对强降水的指示作用要早于反射率因子。
(3)运用EVAD方法计算平均大气散度,变分法计算平均大气垂直速度,对此次降水过程动力条件进行分析,通过与降水强弱变化的对比分析,结果表明：该方法能够反映出此次降水过程的动力学特征,当中低层辐合较强,出现强上升运动时,将会引发短历时强降水天气的产生。
(4)通过四维变分方法(每次输入相邻的两个体扫资料)进行风场的反演,对本次短历时强降水进行中小尺度天气系统分析,得到较为真实的中小尺度天气系统状况,强降水发生在“人”字型切变线的暖切变线的前侧,当暖切变线附近出现中-γ闭合气旋性环流时,降水进一步增强。
Short heavy rainfall happens frequently in Qinhuangdao because that it locates in the west of Bohai bay and the north of Yanshan Mountain and has complex terrain. Severe precipitations in the short time have its unique properties. In this paper, utilizing Micaps information, NCAR/ NCEP reanalysis data, Doppler radar, automatic weather station wind and precipitation data, using WRF model, the radar echo analysis, EVAD method, four-dimensional variation method, analyzing a short duration heavy rain occurred in 6 July 2009 in Qinhuangdao City, the main conclusions are as follows:
(1)Using the WRF model simulate the heavy precipitation, the results shows that the simulated distribution of precipitation is close to the observation, but the rainfall in Qinhuangdao simulates weak. WRF model can simulate the trough moving eastward deepening with the strengthening the sea breeze, the simulated surface convergence line and moisture convergence center has obvious implications for heavy rainfall, but relevant physical quantities simulates a little weak. The reasons may be that the initial field data is density, when the model is interpolating, the smaller the weather system may be smoothed out. Therefore, using conventional data simulate small-scale systems in WRF model also has some limitations.
(2)Analyzing the characteristics of Doppler radar reflectivity, vertical wind profile and radial velocity field in the heavy rainfall, the results show that the vertical wind profile radar products can reflect the atmospheric water vapor content changes in higher level; when the dry cold air in middle layer invades, the rainfall intensity increases; the instructions of Doppler radar's radial velocity field on heavy rainfall is earlier than the reflectivity.
(3)Using EVAD method calculate the average atmospheric divergence, using the variation method calculate the average atmospheric vertical velocity, analyzing the dynamic process of the precipitation, the results show that the method can reflect the dynamic characteristics of the precipitation process, the severe convective weather would be brought out when there was strong convergence of low-mid level Jet Stream and with the severe ascending motion.
(4)By four-Dimensional Variation Method (the data of two adjacent volume scan were input once in so-called 4DVM), to run the wind field interpretation, depending on the analysis for the severe precipitation of micro-and meso scale systems in the short time, the situation of micro-and meso-scale weather system can be reflected truly. The heavy rainfall occurred in the "people"(Chinese character) shaped shear line before the warm the shear line side, when the middle-y cyclonic circulation appears near the warn shear line, the precipitation will enhanced further more.
引文
[1]陈明轩,俞小鼎,谭晓光等.对流天气临近预报技术的发展与研究进展[J].应用气象学报.2004,15(6)：754-766
[2]朱乾根,林锦瑞,寿绍文等.天气学原理和方法(修订本)[M].北京：气象出版社,1992
[3]Rinehart R E, Garvey E T. Three-dimensional storm motion detection by conventional weather radar[J]. Nature.1978,273:287-289.
[4]Michael Dixon, Gerry wiener. Thunder storm identification, tracking, analysis and nowcasting-A radar_base methodology [J].J Atmos Oceanic Technic.1993,10:785-797.
[5]Turner B J, Zawadzkiil, Germann U. Predictability of Precipitation from Continental Radar Images Part III: Operational Nowcasting ImPlementation (MAPLE) [J]. Journal of APPlied Meteorology.2004,43:231-248.
[6]张亚萍,程明虎,夏文梅等.天气雷达回波运动场估测及其在降水临近预报中的应用[J].气象学报,2006,64(5)：631-646.
[7]Lhermitte,RM,and Atlas,Precipitation motion by Pulse Doppler.Preprints Ninth Weather Radar Conf,Boston,Amer Meteor Soc,1961.218-223
[8]Browning,K.A,and R.Weler.The determination of kinematic Properties of a wind field using Doppler radar[J]. APPlMeteor,1968,7.105-113
[9]EasterbrookC C,Estimating horizontal wind fields by two-dimensional curve fitting of single Doppler radar measurements.Preprints 16th Int Conf.on Radar Meteorology,Houston,Amer Meteor Soc,1975.314-319
[10]Waldteufel,P and H.Corbin.On the analysis of single-Doppler radar data[J]. APPlMeteor,1979,18.532-542
[11]Persson G and T.Anderson.Automatic wind field interpretation of Doppler radar radial wind components.In:Pennsyluania Uni.,USA Smhi Pormis Reports.1987.
[12]陶祖钰.从Doppler速度场反演风矢量场的方法[J].气象学报.1992,50(1).82-93
[13]姜海燕,葛润生.一种新的单部多普勒雷达反演技术[J].应用气象学报,2000,11(2)：尺度气象文集[M].北京：气象出版社.1993
[14]丑纪范.天气数值预报中使用过去资料的问题.中国科学,1974,6：635-644
[15]邱崇践,郜吉东.模式误差对变分同化过程影响的数值研究.高原气象,1994,13(4)：449-456.
[16]Sun J.and A.Crook,Dynamical and microphysical retrieval from Doppler radar observations using a cloud and its adjoint.PartⅠ:Model development and simulated data experiments.J.Atmos.Sci.1997,54:1642-1661
[1]俞小鼎,姚秀萍,熊廷南等.多普勒天气雷达原理与业务应用.北京：气象出版社,2005
[2]张培昌,杜秉玉,戴铁王.雷达气象学M.北京：气象出版社2000：294.
[3]Wood VT.Brown R A.Single Doppler Velocity Signature Interpretation of nondivergent environmental winds[J].Journal of Atmospheric and Oceanic Technology,1986,3(1):114-128.
[4]Wood VT.Brown R A.Effeets of Radar Proximity on Single-Doppler Veloeity Singatures of Axisymnetric Rotation and Divergence.Mon.Wea.Rev.,1992,120:2798-2807.
[5]夏文梅,张亚萍,汤达章等.暴雨多普勒天气雷达资料的分析[J].南京气象学院学报,2002,25(6)：787-794.
[6]Lhermitte R M, Atlas D.Precipitation motion by Pulse Doppler.Preprints Ninth Weather Radar Conferenee.Aner.Meteor.Soc.,1961,218-223
[7]Browning K A, Wexler R.The determination of kinematic Proporties of a wind Field using Doppler radar.J.APPl.Meteor.,1968,7(1):105-113
[8]张培昌,杜秉玉,戴铁王.雷达气象学[M].北京：气象出版社,2000
[9]胡明宝,高太长,汤达章.多普勒天气雷达资料发析与应用[M].北京：解放军出版社,2000
[10]Wood VT.Brown R A.Single DoPPler Velocity Signature InterPretation of nondivergent Environmental Winds[J].Journal of AtmosPheric and Oceanic Technology,1986,3(1):114-128.
[11]胡志群,汤达章,梁明珠等.用改善的EVAD技术和变分法计算大气垂直速度.南京气象学院学报,2005,28(3)：344-350.
[1]河北省气象局编著,“河北省天气预报手册”[M],北京：气象出版社,1987
[2]马旭林.一次江淮暴雨过程的中尺度系统发生发展的数值试验及机制分析.南京气象学院硕士学位论文,2004,19-28
[3]Skamarock W. C., Klemp J. B., Dudhia J., Gill D.O.,A Description of the Advanced Reseach WRF Version 2. Available on WRF website:http://www.mmm.ucar.edu/wrf/users/,2005,1-21,51-63,65-74.
[1]俞小鼎,姚秀萍,熊廷南等.多普勒天气雷达原理与业务应用.北京：气象出版社,2005
[2]张京英,漆梁波,王庆华.用雷达风廓线产品分析一次暴雨与高低空急流的关系.气象,2005,31(12)：41-45.
[3]陈楠,降水过程中多普勒雷达速度场特征的研究[D],硕士论文,南京信息工程大学,2008
[4]俞小鼎,姚秀萍,熊廷南等.多普勒天气雷达原理与业务应用.北京：气象出版社,2005
[5]陆大春,蒋年冲.VAD有关产品在临近预报中的应用.应用气象学报,2003,14增156-160.
[6]张沛源,陈荣林,多普勒速度图上的暴雨判据研究.应用气象学报[J].1995,6(3)：373-378
[7]王丽荣,汤达章,胡志群等,多普勒雷达的速度图像特征及其在一次降雪过程中的应用[J].应用气象学报,2006,17(4)：452-458.
[8]张守保,华北回流天气的多尺度结构特征[D],博士论文,南京信息工程大学,2009
[1]Sun J,Crook A.Dynamical and microphysical retrieval from Doppler radar observations using a cloud and its adjioint.Part,Ⅰ:Model development and simulated data experiments.J Atmos Sci,1997,54(12):1642-1661
[2]许小永,四维变分和集合卡尔曼滤波同化多普勒雷达资料的方法及其反演暴雨中尺度结构的研究[D],博士论文,南京信息工程大学,2005
[3]Liu D C and J Nocedal,1989, On the limited memory BFGS method for large scale Optimization.Math Programming 45.503-528.
[4]牟容,刘黎平,许小永等.四维变分方法反演低层风场能力研究[J].气象,2007,33(1)：11-19.
[5]许小永,郑国光.多普勒雷达反演技术及雷达资料在数值模式中的应用[J].气象,2005,31(3)：7-11.
[2]朱乾根,林锦瑞,寿绍文等.天气学原理和方法(修订本)[M].北京：气象出版社,1992
[3]Rinehart R E, Garvey E T. Three-dimensional storm motion detection by conventional weather radar[J]. Nature.1978,273:287-289.
[4]Michael Dixon, Gerry wiener. Thunder storm identification, tracking, analysis and nowcasting-A radar_base methodology [J].J Atmos Oceanic Technic.1993,10:785-797.
[5]Turner B J, Zawadzkiil, Germann U. Predictability of Precipitation from Continental Radar Images Part III: Operational Nowcasting ImPlementation (MAPLE) [J]. Journal of APPlied Meteorology.2004,43:231-248.
[6]张亚萍,程明虎,夏文梅等.天气雷达回波运动场估测及其在降水临近预报中的应用[J].气象学报,2006,64(5)：631-646.
[7]Lhermitte,RM,and Atlas,Precipitation motion by Pulse Doppler.Preprints Ninth Weather Radar Conf,Boston,Amer Meteor Soc,1961.218-223
[8]Browning,K.A,and R.Weler.The determination of kinematic Properties of a wind field using Doppler radar[J]. APPlMeteor,1968,7.105-113
[9]EasterbrookC C,Estimating horizontal wind fields by two-dimensional curve fitting of single Doppler radar measurements.Preprints 16th Int Conf.on Radar Meteorology,Houston,Amer Meteor Soc,1975.314-319
[10]Waldteufel,P and H.Corbin.On the analysis of single-Doppler radar data[J]. APPlMeteor,1979,18.532-542
[11]Persson G and T.Anderson.Automatic wind field interpretation of Doppler radar radial wind components.In:Pennsyluania Uni.,USA Smhi Pormis Reports.1987.
[12]陶祖钰.从Doppler速度场反演风矢量场的方法[J].气象学报.1992,50(1).82-93
[13]姜海燕,葛润生.一种新的单部多普勒雷达反演技术[J].应用气象学报,2000,11(2)：尺度气象文集[M].北京：气象出版社.1993
[14]丑纪范.天气数值预报中使用过去资料的问题.中国科学,1974,6：635-644
[15]邱崇践,郜吉东.模式误差对变分同化过程影响的数值研究.高原气象,1994,13(4)：449-456.
[16]Sun J.and A.Crook,Dynamical and microphysical retrieval from Doppler radar observations using a cloud and its adjoint.PartⅠ:Model development and simulated data experiments.J.Atmos.Sci.1997,54:1642-1661
[1]俞小鼎,姚秀萍,熊廷南等.多普勒天气雷达原理与业务应用.北京：气象出版社,2005
[2]张培昌,杜秉玉,戴铁王.雷达气象学M.北京：气象出版社2000：294.
[3]Wood VT.Brown R A.Single Doppler Velocity Signature Interpretation of nondivergent environmental winds[J].Journal of Atmospheric and Oceanic Technology,1986,3(1):114-128.
[4]Wood VT.Brown R A.Effeets of Radar Proximity on Single-Doppler Veloeity Singatures of Axisymnetric Rotation and Divergence.Mon.Wea.Rev.,1992,120:2798-2807.
[5]夏文梅,张亚萍,汤达章等.暴雨多普勒天气雷达资料的分析[J].南京气象学院学报,2002,25(6)：787-794.
[6]Lhermitte R M, Atlas D.Precipitation motion by Pulse Doppler.Preprints Ninth Weather Radar Conferenee.Aner.Meteor.Soc.,1961,218-223
[7]Browning K A, Wexler R.The determination of kinematic Proporties of a wind Field using Doppler radar.J.APPl.Meteor.,1968,7(1):105-113
[8]张培昌,杜秉玉,戴铁王.雷达气象学[M].北京：气象出版社,2000
[9]胡明宝,高太长,汤达章.多普勒天气雷达资料发析与应用[M].北京：解放军出版社,2000
[10]Wood VT.Brown R A.Single DoPPler Velocity Signature InterPretation of nondivergent Environmental Winds[J].Journal of AtmosPheric and Oceanic Technology,1986,3(1):114-128.
[11]胡志群,汤达章,梁明珠等.用改善的EVAD技术和变分法计算大气垂直速度.南京气象学院学报,2005,28(3)：344-350.
[1]河北省气象局编著,“河北省天气预报手册”[M],北京：气象出版社,1987
[2]马旭林.一次江淮暴雨过程的中尺度系统发生发展的数值试验及机制分析.南京气象学院硕士学位论文,2004,19-28
[3]Skamarock W. C., Klemp J. B., Dudhia J., Gill D.O.,A Description of the Advanced Reseach WRF Version 2. Available on WRF website:http://www.mmm.ucar.edu/wrf/users/,2005,1-21,51-63,65-74.
[1]俞小鼎,姚秀萍,熊廷南等.多普勒天气雷达原理与业务应用.北京：气象出版社,2005
[2]张京英,漆梁波,王庆华.用雷达风廓线产品分析一次暴雨与高低空急流的关系.气象,2005,31(12)：41-45.
[3]陈楠,降水过程中多普勒雷达速度场特征的研究[D],硕士论文,南京信息工程大学,2008
[4]俞小鼎,姚秀萍,熊廷南等.多普勒天气雷达原理与业务应用.北京：气象出版社,2005
[5]陆大春,蒋年冲.VAD有关产品在临近预报中的应用.应用气象学报,2003,14增156-160.
[6]张沛源,陈荣林,多普勒速度图上的暴雨判据研究.应用气象学报[J].1995,6(3)：373-378
[7]王丽荣,汤达章,胡志群等,多普勒雷达的速度图像特征及其在一次降雪过程中的应用[J].应用气象学报,2006,17(4)：452-458.
[8]张守保,华北回流天气的多尺度结构特征[D],博士论文,南京信息工程大学,2009
[1]Sun J,Crook A.Dynamical and microphysical retrieval from Doppler radar observations using a cloud and its adjioint.Part,Ⅰ:Model development and simulated data experiments.J Atmos Sci,1997,54(12):1642-1661
[2]许小永,四维变分和集合卡尔曼滤波同化多普勒雷达资料的方法及其反演暴雨中尺度结构的研究[D],博士论文,南京信息工程大学,2005
[3]Liu D C and J Nocedal,1989, On the limited memory BFGS method for large scale Optimization.Math Programming 45.503-528.
[4]牟容,刘黎平,许小永等.四维变分方法反演低层风场能力研究[J].气象,2007,33(1)：11-19.
[5]许小永,郑国光.多普勒雷达反演技术及雷达资料在数值模式中的应用[J].气象,2005,31(3)：7-11.