基于时空不确定性的对流尺度集合预报效果评估检验
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摘要
针对对流尺度天气系统的高度非线性特征和高分辨率模式预报结果存在时、空不确定性现象,以及当前邻域概率法主要考虑高分辨率预报结果的空间位移误差,而不能有效解决预报结果存在时间超前与滞后问题,将时间因素引入到邻域概率法中,结合一次强飑线过程进行对流尺度集合预报试验,并基于改进后的新型邻域概率法与分数技巧评分,对降水预报进行了不同时、空尺度的效果评估检验。结果表明:(1)邻域集合概率法和概率匹配平均法在极端降水的分数技巧评分远高于传统集合平均,弥补了集合平均对极端降水预报能力偏低的缺陷。(2)对于此类飑线过程的对流尺度天气系统而言,邻域半径为15—45 km的空间尺度能够改善降水位移误差的空间不确定性,并使其预报效果达到最优,其中15—30 km的邻域半径对于尺度更小的大量级降水事件预报能力更强。(3)对流尺度降水预报考虑时间尺度与降水强度存在着对应关系,不同时间尺度可以捕获到不同量级降水的时间不确定性。同时,时间尺度与空间尺度对于降水预报效果的影响是相互关联的。(4)改进的邻域概率法能够同时体现高分辨率模式预报结果在对流尺度降水事件上存在的时、空不确定性,实现了对流尺度降水在时、空尺度上的综合评估,并能为不同量级降水提供与其时、空尺度相匹配的概率预报结果。
Considering the highly non-linear characteristics of convective-scale weather systems and spatial-temporal uncertainties in high-resolution numerical forecasting,a convection-allowing ensemble forecast experiment has been conducted to simulate a strong squall line.The neighborhood probability(NP)method mainly considers the spatial displacement error in high resolution model forecasts,and cannot effectively address the problem of difference in event occurrence time between forecasts and observations.Therefore,a time factor is introduced into the NP method in this study.And based on the improved NP method and fractions skill score(FSS),the precipitation forecast of the strong squall line is verified on different spatial-temporal scales.The conclusions are as follows:(1)The FSS of extreme precipitation produced by the neighborhood ensemble probability(NEP)and probability matched mean(PMM)methods is higher than that produced by the traditional ensemble mean(EM)method,and the former two methods overcome the shortcomings of the EM method in predicting extreme precipitation.(2)For the squall line process investigated in the present study,the spatial scale of 15-45 km can reduce the spatial uncertainty in displacement error of precipitation forecast and optimize the forecast effect.The spatial scale of 15-30 km exhibits a better forecast capability for smaller-scale extreme precipitation events.(3)The convective-scale precipitation forecast has a corresponding relationship between temporal scale and rainfall intensity,and different temporal scales can capture temporal uncertainties in precipitation with different magnitudes.Meanwhile,the spatial and temporal scales are inter-related for the precipitation forecast effect.(4)The improved NP method can simultaneously show temporal and spatial uncertainties in high-resolution model forecast of convective-scale precipitation,achieve comprehensive evaluation of convective-scale precipitation on temporal and spatial scales,and provide skillful probabilistic forecast results for precipitation with various magnitudes and corresponding spatial-temporal scales.
Considering the highly non-linear characteristics of convective-scale weather systems and spatial-temporal uncertainties in high-resolution numerical forecasting,a convection-allowing ensemble forecast experiment has been conducted to simulate a strong squall line.The neighborhood probability(NP)method mainly considers the spatial displacement error in high resolution model forecasts,and cannot effectively address the problem of difference in event occurrence time between forecasts and observations.Therefore,a time factor is introduced into the NP method in this study.And based on the improved NP method and fractions skill score(FSS),the precipitation forecast of the strong squall line is verified on different spatial-temporal scales.The conclusions are as follows:(1)The FSS of extreme precipitation produced by the neighborhood ensemble probability(NEP)and probability matched mean(PMM)methods is higher than that produced by the traditional ensemble mean(EM)method,and the former two methods overcome the shortcomings of the EM method in predicting extreme precipitation.(2)For the squall line process investigated in the present study,the spatial scale of 15-45 km can reduce the spatial uncertainty in displacement error of precipitation forecast and optimize the forecast effect.The spatial scale of 15-30 km exhibits a better forecast capability for smaller-scale extreme precipitation events.(3)The convective-scale precipitation forecast has a corresponding relationship between temporal scale and rainfall intensity,and different temporal scales can capture temporal uncertainties in precipitation with different magnitudes.Meanwhile,the spatial and temporal scales are inter-related for the precipitation forecast effect.(4)The improved NP method can simultaneously show temporal and spatial uncertainties in high-resolution model forecast of convective-scale precipitation,achieve comprehensive evaluation of convective-scale precipitation on temporal and spatial scales,and provide skillful probabilistic forecast results for precipitation with various magnitudes and corresponding spatial-temporal scales.
引文
陈朝平,冯汉中,陈静.2010.基于贝叶斯方法的四川暴雨集合概率预报产品释用.气象,36(5):32-39.Chen C P,Feng H Z,Chen J.2010.Application of Sichuan heavy rainfall ensemble prediction probability products based on Bayesian method.Meteor Mon,36(5):32-39(in Chinese)
高峰,闵锦忠,孔凡铀.2010.基于增长模繁殖法的风暴尺度集合预报试验.高原气象,29(2):429-436.Gao F,Min J Z,Kong F Y.2010.Experiment of the storm-scale ensemble forecast based on breeding of growing mode.Plateau Meteor,29(2):429-436(in Chinese)
李俊,杜钧,陈超君.2015a.“频率匹配法”在集合降水预报中的应用研究.气象,41(6):674-684.Li J,Du J,Chen C J.2015a.Applications of"frequency-matching"method to ensemble precipitation forecasts.Meteor Mon,41(6):674-684(in Chinese)
李俊,杜钧,刘羽.2015b.北京“7.21”特大暴雨不同集合预报方案的对比试验.气象学报,73(1):50-71.Li J,Du J,Liu Y.2015b.A comparison of initial condition-,multi-physics-and stochastic physics-based ensembles in predicting Beijing"7.21"excessive storm rain event.Acta Meteor Sinica,73(1):50-71(in Chinese)
刘琳,陈静,程龙等.2013.基于集合预报的中国极端强降水预报方法研究.气象学报,71(5):853-866.Liu L,Chen J,Cheng L,et al.2013.Study of the ensemble-based forecast of extremely heavy rainfalls in China:Experiments for July 2011 cases.Acta Meteor Sinica,71(5):853-866(in Chinese)
潘留杰,张宏芳,陈小婷等.2015.基于邻域法的高分辨率模式降水的预报能力分析.热带气象学报,31(5):632-642.Pan L J,Zhang H F,Chen X T,et al.2015.Neighborhood-based precipitation forecasting capability analysis of high-resolution models.J Trop Meteor,31(5):632-642(in Chinese)
王晨稀,姚建群.2008.对一次局地短时强降水过程的集合预报研究.高原气象,27(6):1229-1239.Wang C X,Yao J Q.2008.Ensemble forecasting of a local short-lived severe precipitation.Plateau Meteor,27(6):1229-1239(in Chinese)
张宇彤,矫梅燕,陈静等.2016.基于贝叶斯方法的极端降水概率预报试验.气象,42(7):799-808.Zhang Y T,Jiao M Y,Chen J,et al.2016.Probabilistic forecasting of extreme precipitation experiment based on Bayesian theory.Meteor Mon,42(7):799-808(in Chinese)
庄潇然,闵锦忠,蔡沅辰等.2016.不同大尺度强迫条件下考虑初始场与侧边界条件不确定性的对流尺度集合预报试验.气象学报,74(2):244-258.Zhuang X R,Min J Z,Cai Y C,et al.2016.Convective-scale ensemble prediction experiments under different large-scale forcing with consideration of uncertainties in initial and lateral boundary condition.Acta Meteor Sinica,74(2):244-258(in Chinese)
庄潇然,闵锦忠,王世璋等.2017.风暴尺度集合预报中的混合初始扰动方法及其在北京2012年“7.21”暴雨预报中的应用.大气科学,41(1):30-42.Zhuang X R,Min J Z,Wang S Z,et al.2017.A blending method for storm-scale ensemble forecast and its application to Beijing extreme precipitation event on July21,2012.Chinese J Atmos Sci,41(1):30-42(in Chinese)
Baldwin M E,Kain J S.2006.Sensitivity of several performance measures to displacement error,bias,and event frequency.Wea Forecasting,21(4):636-648
Clark A J,Gallus W A Jr,Xue M,et al.2009.A comparison of precipitation forecast skill between small convection-allowing and large convection-parameterizing ensembles.Wea Forecasting,24(4):1121-1140
Clark A J,Kain J S,Stensrud D J,et al.2011.Probabilistic precipitation forecast skill as a function of ensemble size and spatial scale in a convection-allowing ensemble.Mon Wea Rev,139(5):1410-1418
Clark A J,Weiss S J,Kain J S,et al.2012.An overview of the2010 hazardous weather testbed experimental forecast program spring experiment.Bull Amer Meteor Soc,93(1):55-74
Duc L,Saito K,Seko H.2013.Spatial-temporal fractions verification for high-resolution ensemble forecasts.Tellus A:Dyn Meteor Oceanogr,65(1):18171
Ebert E E.2001.Ability of a poor man's ensemble to predict the probability and distribution of precipitation.Mon Wea Rev,129(10):2461-2480
Ebert E E.2008.Fuzzy verification of high-resolution gridded forecasts:A review and proposed framework.Meteor Appl,15(1):51-64
Ebert E E.2009.Neighborhood verification:A strategy for rewarding close forecasts.Wea Forecasting,24(6):1498-1510
Kong F Y,Droegemeier K K,Hickmon N L.2006.Multiresolution ensemble forecasts of an observed tornadic thunderstorm system.Part I:comparsion of coarse-and fine-grid Experiments.Mon Wea Rev,134(3):807-833
Kong F Y,Xue M,Thomas K W,et al.2009.A real-time stormscale ensemble forecast system:2009 spring experiment∥Proceedings of the 23nd Conference on Weather Analysis Forecasting/19th Conference on Numerical Weather Prediction.Omaha,Nebraska:American Meteorological Society,16A.3pp
Li X,He H R,Chen C H,et al.2017.A convection-allowing ensemble forecast based on the breeding growth mode and associated optimization of precipitation forecast.J Meteor Res,31(5):955-964
Mittermaier M,Roberts N.2010.Intercomparison of spatial forecast verification methods:Identifying skillful spatial scales using the fractions skill score.Wea Forecasting,25(1):343-354
Roberts N M,Lean H W.2008.Scale-selective verification of rainfall accumulations from high-resolution forecasts of convective events.Mon Wea Rev,136(1):78-97
Schwartz C S,Kain J S,Weiss S J,et al.2009.Next-day convection-allowing WRF model guidance:A second look at 2-km versus 4-km grid spacing.Mon Wea Rev,137(10):3351-3372
Schwartz C S,Kain J S,Weiss S J,et al.2010.Toward improved convection-allowing ensembles:Model physics sensitivities and optimizing probabilistic guidance with small ensemble membership.Wea Forecasting,25(1):263-280
Schwartz C S,Romine G S,Weisman M L,et al.2015a.A realtime convection-allowing ensemble prediction system initialized by mesoscale ensemble Kalman filter analyses.Wea Forecasting,30(5):1158-1181
Schwartz C S,Romine G S,Sobash R A,et al.2015b.NCAR's experimental real-time convection-allowing ensemble prediction system.Wea Forecasting,30(6):1645-1654
Weusthoff T,Ament F,Arpagaus M,et al.2010.Assessing the benefits of convection-permitting models by neighborhood verification:Examples from MAP D-PHASE.Mon Wea Rev,138(9):3418-3433
Xue M,Kong F,Thomas K W,et al.2010.CAPS realtime storm scale ensemble and high resolution forecasts for the NOAA hazardous weather testbed 2010 spring experiment∥Proceedings of the 25th Conference on Severe Local Storms.Denver,Colorado:Amer Meteor Soc,7B.3pp
高峰,闵锦忠,孔凡铀.2010.基于增长模繁殖法的风暴尺度集合预报试验.高原气象,29(2):429-436.Gao F,Min J Z,Kong F Y.2010.Experiment of the storm-scale ensemble forecast based on breeding of growing mode.Plateau Meteor,29(2):429-436(in Chinese)
李俊,杜钧,陈超君.2015a.“频率匹配法”在集合降水预报中的应用研究.气象,41(6):674-684.Li J,Du J,Chen C J.2015a.Applications of"frequency-matching"method to ensemble precipitation forecasts.Meteor Mon,41(6):674-684(in Chinese)
李俊,杜钧,刘羽.2015b.北京“7.21”特大暴雨不同集合预报方案的对比试验.气象学报,73(1):50-71.Li J,Du J,Liu Y.2015b.A comparison of initial condition-,multi-physics-and stochastic physics-based ensembles in predicting Beijing"7.21"excessive storm rain event.Acta Meteor Sinica,73(1):50-71(in Chinese)
刘琳,陈静,程龙等.2013.基于集合预报的中国极端强降水预报方法研究.气象学报,71(5):853-866.Liu L,Chen J,Cheng L,et al.2013.Study of the ensemble-based forecast of extremely heavy rainfalls in China:Experiments for July 2011 cases.Acta Meteor Sinica,71(5):853-866(in Chinese)
潘留杰,张宏芳,陈小婷等.2015.基于邻域法的高分辨率模式降水的预报能力分析.热带气象学报,31(5):632-642.Pan L J,Zhang H F,Chen X T,et al.2015.Neighborhood-based precipitation forecasting capability analysis of high-resolution models.J Trop Meteor,31(5):632-642(in Chinese)
王晨稀,姚建群.2008.对一次局地短时强降水过程的集合预报研究.高原气象,27(6):1229-1239.Wang C X,Yao J Q.2008.Ensemble forecasting of a local short-lived severe precipitation.Plateau Meteor,27(6):1229-1239(in Chinese)
张宇彤,矫梅燕,陈静等.2016.基于贝叶斯方法的极端降水概率预报试验.气象,42(7):799-808.Zhang Y T,Jiao M Y,Chen J,et al.2016.Probabilistic forecasting of extreme precipitation experiment based on Bayesian theory.Meteor Mon,42(7):799-808(in Chinese)
庄潇然,闵锦忠,蔡沅辰等.2016.不同大尺度强迫条件下考虑初始场与侧边界条件不确定性的对流尺度集合预报试验.气象学报,74(2):244-258.Zhuang X R,Min J Z,Cai Y C,et al.2016.Convective-scale ensemble prediction experiments under different large-scale forcing with consideration of uncertainties in initial and lateral boundary condition.Acta Meteor Sinica,74(2):244-258(in Chinese)
庄潇然,闵锦忠,王世璋等.2017.风暴尺度集合预报中的混合初始扰动方法及其在北京2012年“7.21”暴雨预报中的应用.大气科学,41(1):30-42.Zhuang X R,Min J Z,Wang S Z,et al.2017.A blending method for storm-scale ensemble forecast and its application to Beijing extreme precipitation event on July21,2012.Chinese J Atmos Sci,41(1):30-42(in Chinese)
Baldwin M E,Kain J S.2006.Sensitivity of several performance measures to displacement error,bias,and event frequency.Wea Forecasting,21(4):636-648
Clark A J,Gallus W A Jr,Xue M,et al.2009.A comparison of precipitation forecast skill between small convection-allowing and large convection-parameterizing ensembles.Wea Forecasting,24(4):1121-1140
Clark A J,Kain J S,Stensrud D J,et al.2011.Probabilistic precipitation forecast skill as a function of ensemble size and spatial scale in a convection-allowing ensemble.Mon Wea Rev,139(5):1410-1418
Clark A J,Weiss S J,Kain J S,et al.2012.An overview of the2010 hazardous weather testbed experimental forecast program spring experiment.Bull Amer Meteor Soc,93(1):55-74
Duc L,Saito K,Seko H.2013.Spatial-temporal fractions verification for high-resolution ensemble forecasts.Tellus A:Dyn Meteor Oceanogr,65(1):18171
Ebert E E.2001.Ability of a poor man's ensemble to predict the probability and distribution of precipitation.Mon Wea Rev,129(10):2461-2480
Ebert E E.2008.Fuzzy verification of high-resolution gridded forecasts:A review and proposed framework.Meteor Appl,15(1):51-64
Ebert E E.2009.Neighborhood verification:A strategy for rewarding close forecasts.Wea Forecasting,24(6):1498-1510
Kong F Y,Droegemeier K K,Hickmon N L.2006.Multiresolution ensemble forecasts of an observed tornadic thunderstorm system.Part I:comparsion of coarse-and fine-grid Experiments.Mon Wea Rev,134(3):807-833
Kong F Y,Xue M,Thomas K W,et al.2009.A real-time stormscale ensemble forecast system:2009 spring experiment∥Proceedings of the 23nd Conference on Weather Analysis Forecasting/19th Conference on Numerical Weather Prediction.Omaha,Nebraska:American Meteorological Society,16A.3pp
Li X,He H R,Chen C H,et al.2017.A convection-allowing ensemble forecast based on the breeding growth mode and associated optimization of precipitation forecast.J Meteor Res,31(5):955-964
Mittermaier M,Roberts N.2010.Intercomparison of spatial forecast verification methods:Identifying skillful spatial scales using the fractions skill score.Wea Forecasting,25(1):343-354
Roberts N M,Lean H W.2008.Scale-selective verification of rainfall accumulations from high-resolution forecasts of convective events.Mon Wea Rev,136(1):78-97
Schwartz C S,Kain J S,Weiss S J,et al.2009.Next-day convection-allowing WRF model guidance:A second look at 2-km versus 4-km grid spacing.Mon Wea Rev,137(10):3351-3372
Schwartz C S,Kain J S,Weiss S J,et al.2010.Toward improved convection-allowing ensembles:Model physics sensitivities and optimizing probabilistic guidance with small ensemble membership.Wea Forecasting,25(1):263-280
Schwartz C S,Romine G S,Weisman M L,et al.2015a.A realtime convection-allowing ensemble prediction system initialized by mesoscale ensemble Kalman filter analyses.Wea Forecasting,30(5):1158-1181
Schwartz C S,Romine G S,Sobash R A,et al.2015b.NCAR's experimental real-time convection-allowing ensemble prediction system.Wea Forecasting,30(6):1645-1654
Weusthoff T,Ament F,Arpagaus M,et al.2010.Assessing the benefits of convection-permitting models by neighborhood verification:Examples from MAP D-PHASE.Mon Wea Rev,138(9):3418-3433
Xue M,Kong F,Thomas K W,et al.2010.CAPS realtime storm scale ensemble and high resolution forecasts for the NOAA hazardous weather testbed 2010 spring experiment∥Proceedings of the 25th Conference on Severe Local Storms.Denver,Colorado:Amer Meteor Soc,7B.3pp