CINRAD-SA双偏振雷达资料在降水估测中的应用初探
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摘要
对基于水平反射率ZH和差分传播相移率K_(DP)的降水估测综合法R(C)进行了改进,并对广州S波段双偏振雷达2016年2次飑线和2次台风降水过程的Φ_(DP)使用小波分析进行滤波处理,在此基础上使用变距最小二乘法拟合得到K_(DP)的值。分别使用R(C)和R(Z_H)法对2次飑线和2次台风降水过程进行降水估算,将估算结果和雨量计小时雨量进行了对比,并将两种方法的评估结果进行了对比。结果表明:(1)对于飑线类型降水,R(C)法对5 mm·h~(-1)以上的降水估测精度要好于R(Z_H)法,且降水率越大,R(C)法优势越明显,当降水率≥20 mm·h~(-1)时,两次过程R(C)法比R(Z_H)法的平均相对误差(RE)降低了17. 2%,平均绝对误差(AE)减少了1.89 mm,平均均方根误差(RMSE)减少了1.66 mm;(2)对于台风类型降水,R(C)法对5 mm·h~(-1)以上的降水估测精度也好于R(Z_H)法,当降水率≥20 mm·h~(-1)时,两次过程R(C)法比R(Z_H)法的平均RE降低了33. 19%,平均AE减少了3. 95 mm,平均RMSE减少了4.05 mm;(3)对于飑线和台风两种类型降水R(C)法都明显改善了降水率较大时的R(Z_H)法低估问题,但R(C)法在降水率>10 mm·h~(-1)时也存在低估,可能是由雨滴谱资料观测误差导致拟合的系数偏小或雷达硬件造成的观测偏差等造成的。
In this paper, the method of QPE based on Z_H and K_(DP)[R(C) method] is improved, and Φ_(DP) of Guangzhou S-band dual polarization radar during two squall lines and two typhoons in 2016 is filtered by wavelet analysis, and then K_(DP) is estimated by Φ_(DP) in 1. 5-4. 5 km resolution. The rainfall of the squall lines and typhoons is estimated by R(C) and R(Z_H) methods, and the estimated result is compared with the hourly rainfall gauge. In addition, the evaluating results of R(C) and R(Z_H) methods are compared to each other. The results show that(1) for squall lines,R(C) is better than R(Z_H) when the rainfall rate is higher than 5 mm · h~(-1). The higher the rainfall rate is, the more obvious the advantage of R(C) will be.When the rainfall rate is higher than 20 mm · h~(-1), the average RE decreases by 17. 2%, the average AE decreases by 1. 89 mm, and the average RMSE decreases by 1. 66 mm.(2) For typhoons, R(C) is better than R(Z_H) when the rainfall rate is higher than 5 mm · h~(-1). When the rainfall rate is higher than 20 mm · h~(-1),the average RE of R(C) is 33. 1 % lower than that of R(Z_H), the average AE is reduced by 3. 95 mm, and the average RMSE is reduced by 4. 05 mm. In general, R(C) could solve the underestimate problem existing in R(Z_H) method. However, R(C) could also underestimate the precipitation when the rainfall rate is higher than 10 mm · h~(-1). The possible reason is the small value of the coefficient fitted by the raindrop spectrum data because of the observation error or the observation error caused by the radar hardware.
In this paper, the method of QPE based on Z_H and K_(DP)[R(C) method] is improved, and Φ_(DP) of Guangzhou S-band dual polarization radar during two squall lines and two typhoons in 2016 is filtered by wavelet analysis, and then K_(DP) is estimated by Φ_(DP) in 1. 5-4. 5 km resolution. The rainfall of the squall lines and typhoons is estimated by R(C) and R(Z_H) methods, and the estimated result is compared with the hourly rainfall gauge. In addition, the evaluating results of R(C) and R(Z_H) methods are compared to each other. The results show that(1) for squall lines,R(C) is better than R(Z_H) when the rainfall rate is higher than 5 mm · h~(-1). The higher the rainfall rate is, the more obvious the advantage of R(C) will be.When the rainfall rate is higher than 20 mm · h~(-1), the average RE decreases by 17. 2%, the average AE decreases by 1. 89 mm, and the average RMSE decreases by 1. 66 mm.(2) For typhoons, R(C) is better than R(Z_H) when the rainfall rate is higher than 5 mm · h~(-1). When the rainfall rate is higher than 20 mm · h~(-1),the average RE of R(C) is 33. 1 % lower than that of R(Z_H), the average AE is reduced by 3. 95 mm, and the average RMSE is reduced by 4. 05 mm. In general, R(C) could solve the underestimate problem existing in R(Z_H) method. However, R(C) could also underestimate the precipitation when the rainfall rate is higher than 10 mm · h~(-1). The possible reason is the small value of the coefficient fitted by the raindrop spectrum data because of the observation error or the observation error caused by the radar hardware.
引文
曹俊武,胡志群,陈晓辉,等,2011.影响双线偏振雷达相位探测精度的分析[J].高原气象,30(3):817-822. Cao J W,IIu Z Q,Chen X II, et al.2011. Accuracy analysis of dual-linear polarization signal-process measurement[J]. Plateau Meteor,30(3):817-822(in Chinese).
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陈静,钤伟妙,韩军彩,等,2015.基于动态Z-I关系雷达回波定量估测降水方法研究[J].气象,41(3):296-303. Chen J,Qian W M,Han J C,et al,2015. An approach for radar quantitative precipitation estimate based on Z-I relations varying with time and space[J]. Meteor Mon,41(3):296-303(in Chinese).
勾亚彬,刘黎平,杨杰,等,2014.基于雷达组网拼图的定量降水估测算法业务应用及效果评估[J].气象学报,72(4):731-748. Gou Y B,Liu LP,Yang J,et al,2014. Operational application and evaluation of the quantitative precipitation estimates algorithm based on the multi-radar mosaic[J]. Acta Meteor Sinica,72(4):731-748(in Chinese).
胡志群,刘黎平,楚荣忠,等,2008. X波段双线偏振雷达不同衰减订正方法对比及其对降水估测影响研究[J].气象学报,66(2):251-261. Hu Z Q,Liu L P,Chu R Z,et al.2008. Comparison of different attenuation correction methods and their affects on estimated rainfall using X-band dual linear polarimetric radar[J].Acta Meteor Sinica,66(2):251-261(in Chinese).
刘黎平,葛润生,张沛源,2002.双线偏振多普勒天气雷达遥测降水强度和液态含水量的方法和精度研究[J].大气科学,26(5):709-719. Liu L P,Ge R S, Zhang P Y, 2002. A study of method and accuracy of rainfall rate and liquid water content measurements by dual linear polarization doppler radar[J]. Chinese J Atmos Sci[J],26(5):709-719(in Chinese).
马中元,苏俐敏,湛芸,等,2014.一次强飑线及飑前中小尺度系统特征分析[J].气象,40(8):916-929. Ma Z Y,Su L M,Chen Y,et al,2014. Characteristics of mesoscale and microscale systems during a severe squall line process[J]. Meteor Mon, 40(8):916-929(in Chinese).
王建林,刘黎平,曹俊武,2005.双线偏振多普勒雷达估算降水方法的比较研究[J].气象,31(8):25-30,41. Wang J L,Liu L P,Cao J W,2005. A comparison of methods of rainfall rate measurements by dual linear polarization doppler radar[J]. Meteor Mon,31(8):25-30,41(in Chinese).
王俊,姚展予,侯淑梅,等,2016.一次飑线过程的雨滴谱特征研究[J].气象学报,74(3):450-464. Wang J,Yao Z Y,Hou S M,et al,2016. Characteristics of the raindrop size distribution in a squall line measured by thies optical disdrometers[J]. Acta Meteor Sinica,74(3):450-464(in Chinese).
汪舵,刘黎平,吴翀,2017.基于相态识别的S波段双线偏振雷达最优化定量降水估测方法研究[J].气象,43(9):1041-1051. Wang D,Liu L P,Wu C,2017. An optimization rainfall algorithm of Sband dual-polarization radar based on hydrometeor identification[J]. Meteor Mon,43(9):1041-1051(in Chinese).
魏庆,胡志群,刘黎平,等,2016. C波段偏振雷达数据预处理及在降水估计中的应用[J].高原气象,35(1):231-243. Wei Q,Hu Z Q,Liu L P,et al,2016. C-band polarization radar data pre-processing and its application to rainfall estimation[J]. Plateau Meteor,35(1):231-243(in Chinese).
Aydin K,Bringi V N, Liu L, 1995. Rain-rate estimation in the presence of hail using S-band specific differential phase and other radar parameters[J]. J Appl Meteor,34(2):404-410.
Brandes E A,Zhang G F,Vivekanandan J,2003. An evaluation of a drop distribution-based polarimetric radar rainfall estimator[J].J Appl Meteor,42(5):652-660.
Chandrasekar V, Bringi V N, Balakrishnan N, et al.1990. Error structure of multiparameter radar and surface measurements of rainfall. PartⅢ:specific differential phase[J]. J Atmos Ocean Tech,7(5):621-629.
Hu Z Q,Liu LP,Wang R,2012. A quality assurance procedure andevaluation of rainfall estimates for C-band polarimetric radar[J]. Adv Atmos Sci,29(1):144-156.
Hu Z Q,Liu L P,Wu L L,et al,2015. A comparison of de-noising methods for differential phase shift and associated rainfall estimation[J]. J Meteor Res,29(2):315-327.
Hubbert J,Bringi V N, 1995. An iterative filtering technique for the analysis of copolar differential phase and dual-frequency radar measurements[J]. J Atmos Ocean Technol,12(3):64 3-648.
Liu L P,Hu Z Q,Fang W G,et al,2010. Calibration and data quality analysis with mobile C-band polarimetric radar[J]. J Meteor Res,24(4):501-509.
Matrosov S Y,Kropfli R A.Reinking R F,et al,1999. Prospects for measuring rainfall using propagation differential phase in X-and Ka radar bands[J]. J Appl Meteor,38(6):766-776.
Ryzhkov A V,Diederich M,Zhang P F,et al,2014. Potential utilization of specific attenuation for rainfall estimation, mitigation ofpartial beam blockage,and radar networking[J]. J Atmos Ocean Technol,31(3):599-619.
Seliga T A,Bringi V N,1978. Differential reflectivity and differential phase shift:applications in radar meteorology[J]. Radio Sci,13(2):271-275.
Wang Y T, Chandrasekar V,2009. Algorithm for estimation of the specific differential phase[J]. J Atmos Ocean Technol, 26(12):2565-2578.
Wu C,Liu L P,Wei M,et al,2018. Statistics-based optimization of the polarimetric radar hydrometeor classification algorithm and its application for a squall line in South China[J]. Adv Atmos Sci,35(3):296-316.
Zrnic D S,Ryzhkov A V, 1996. Advantages of rain measurements using specific differential phase[J]. J Atmos Ocean Technol,13(2):454-464.
陈超,胡志群,胡胜,等,2018.广州S波段双偏振雷达数据质量初步分析[J].热带气象学报,34(1):59-67. Chen C,IIu Z Q,IIu S,et al,2018. Preliminary analysis of data quality of guangzhou Sband polarimetric weather radar[J]. J Tropical Meteor, 34(1):59-67(in Chinese).
陈静,钤伟妙,韩军彩,等,2015.基于动态Z-I关系雷达回波定量估测降水方法研究[J].气象,41(3):296-303. Chen J,Qian W M,Han J C,et al,2015. An approach for radar quantitative precipitation estimate based on Z-I relations varying with time and space[J]. Meteor Mon,41(3):296-303(in Chinese).
勾亚彬,刘黎平,杨杰,等,2014.基于雷达组网拼图的定量降水估测算法业务应用及效果评估[J].气象学报,72(4):731-748. Gou Y B,Liu LP,Yang J,et al,2014. Operational application and evaluation of the quantitative precipitation estimates algorithm based on the multi-radar mosaic[J]. Acta Meteor Sinica,72(4):731-748(in Chinese).
胡志群,刘黎平,楚荣忠,等,2008. X波段双线偏振雷达不同衰减订正方法对比及其对降水估测影响研究[J].气象学报,66(2):251-261. Hu Z Q,Liu L P,Chu R Z,et al.2008. Comparison of different attenuation correction methods and their affects on estimated rainfall using X-band dual linear polarimetric radar[J].Acta Meteor Sinica,66(2):251-261(in Chinese).
刘黎平,葛润生,张沛源,2002.双线偏振多普勒天气雷达遥测降水强度和液态含水量的方法和精度研究[J].大气科学,26(5):709-719. Liu L P,Ge R S, Zhang P Y, 2002. A study of method and accuracy of rainfall rate and liquid water content measurements by dual linear polarization doppler radar[J]. Chinese J Atmos Sci[J],26(5):709-719(in Chinese).
马中元,苏俐敏,湛芸,等,2014.一次强飑线及飑前中小尺度系统特征分析[J].气象,40(8):916-929. Ma Z Y,Su L M,Chen Y,et al,2014. Characteristics of mesoscale and microscale systems during a severe squall line process[J]. Meteor Mon, 40(8):916-929(in Chinese).
王建林,刘黎平,曹俊武,2005.双线偏振多普勒雷达估算降水方法的比较研究[J].气象,31(8):25-30,41. Wang J L,Liu L P,Cao J W,2005. A comparison of methods of rainfall rate measurements by dual linear polarization doppler radar[J]. Meteor Mon,31(8):25-30,41(in Chinese).
王俊,姚展予,侯淑梅,等,2016.一次飑线过程的雨滴谱特征研究[J].气象学报,74(3):450-464. Wang J,Yao Z Y,Hou S M,et al,2016. Characteristics of the raindrop size distribution in a squall line measured by thies optical disdrometers[J]. Acta Meteor Sinica,74(3):450-464(in Chinese).
汪舵,刘黎平,吴翀,2017.基于相态识别的S波段双线偏振雷达最优化定量降水估测方法研究[J].气象,43(9):1041-1051. Wang D,Liu L P,Wu C,2017. An optimization rainfall algorithm of Sband dual-polarization radar based on hydrometeor identification[J]. Meteor Mon,43(9):1041-1051(in Chinese).
魏庆,胡志群,刘黎平,等,2016. C波段偏振雷达数据预处理及在降水估计中的应用[J].高原气象,35(1):231-243. Wei Q,Hu Z Q,Liu L P,et al,2016. C-band polarization radar data pre-processing and its application to rainfall estimation[J]. Plateau Meteor,35(1):231-243(in Chinese).
Aydin K,Bringi V N, Liu L, 1995. Rain-rate estimation in the presence of hail using S-band specific differential phase and other radar parameters[J]. J Appl Meteor,34(2):404-410.
Brandes E A,Zhang G F,Vivekanandan J,2003. An evaluation of a drop distribution-based polarimetric radar rainfall estimator[J].J Appl Meteor,42(5):652-660.
Chandrasekar V, Bringi V N, Balakrishnan N, et al.1990. Error structure of multiparameter radar and surface measurements of rainfall. PartⅢ:specific differential phase[J]. J Atmos Ocean Tech,7(5):621-629.
Hu Z Q,Liu LP,Wang R,2012. A quality assurance procedure andevaluation of rainfall estimates for C-band polarimetric radar[J]. Adv Atmos Sci,29(1):144-156.
Hu Z Q,Liu L P,Wu L L,et al,2015. A comparison of de-noising methods for differential phase shift and associated rainfall estimation[J]. J Meteor Res,29(2):315-327.
Hubbert J,Bringi V N, 1995. An iterative filtering technique for the analysis of copolar differential phase and dual-frequency radar measurements[J]. J Atmos Ocean Technol,12(3):64 3-648.
Liu L P,Hu Z Q,Fang W G,et al,2010. Calibration and data quality analysis with mobile C-band polarimetric radar[J]. J Meteor Res,24(4):501-509.
Matrosov S Y,Kropfli R A.Reinking R F,et al,1999. Prospects for measuring rainfall using propagation differential phase in X-and Ka radar bands[J]. J Appl Meteor,38(6):766-776.
Ryzhkov A V,Diederich M,Zhang P F,et al,2014. Potential utilization of specific attenuation for rainfall estimation, mitigation ofpartial beam blockage,and radar networking[J]. J Atmos Ocean Technol,31(3):599-619.
Seliga T A,Bringi V N,1978. Differential reflectivity and differential phase shift:applications in radar meteorology[J]. Radio Sci,13(2):271-275.
Wang Y T, Chandrasekar V,2009. Algorithm for estimation of the specific differential phase[J]. J Atmos Ocean Technol, 26(12):2565-2578.
Wu C,Liu L P,Wei M,et al,2018. Statistics-based optimization of the polarimetric radar hydrometeor classification algorithm and its application for a squall line in South China[J]. Adv Atmos Sci,35(3):296-316.
Zrnic D S,Ryzhkov A V, 1996. Advantages of rain measurements using specific differential phase[J]. J Atmos Ocean Technol,13(2):454-464.