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数值预报中自由度的压缩及误差相似性规律
Compression for Freedom Degree in Numerical Weather Prediction and the Error Analogy
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摘要: 利用历史资料的有用信息提高数值模式预报水平是长期以来人们努力的目标。该文提出了一种在气候吸引子上缩小初始场自由度的相似选取方法, 有效滤除了小尺度分量，避开了原有相似选取中自由度太大，相似选取困难的问题。分析表明：相似初值间的模式预报误差存在相似性，依此估计的预报误差与实际预报误差很接近。在空间分布特征上，相似初值间的模式预报误差也有很好的一致性。这为发展相似 动力方法，利用历史资料改进数值模式提供了支持。Abstract: A substantial improvement in the skill of numerical weather prediction has been achieved in recent years. Useful skill typically extends numerical weather prediction from present day to about 6 days. But for longer timescale, such as 6—15 days, the forecast quality is poor. It is necessary to improve the quality of the results. Utilizing useful information in historical data to improve the prediction skill of numerical model has been considered as a goal. The analogue dynamical method is one of these optimum methods to combine dynamical methods and statistical methods together. However, the analogue selection is very hard due to broad freedom in traditional analogue selection methods. So an analogue selection method under small degree of freedom is proposed. By the method degree of freedom on low dimensional climate attractor is reduced, and small scale components are filtered. This method is based on the theory that the high dimensional phase space in a forced dissipative nonlinear system eventually evolves into a low dimensional attractor, while small scale high frequency patterns are dissipated. Based on compression for degree of freedom of the initial field, an analogue index is defined. In order to further develop the analogue dynamical method, the regularity of the error similarity is investigated. Analyses show that similar initial conditions lead to analogical characteristics of forecast errors. Compared with the system error, the error under analogical initial condition is more close to actual forecast error. Meanwhile, in the spatial scale, forecast errors between analogical initial conditions are well consistent. The preliminary results of the forecast experiments on a complicated T63 Dynamical Extended Range Forecasting model of NCC/CMA show that the analogue dynamical method can effectively reduce the model error. Results provide support for further developing the analogue dynamical method. Evidently, further theoretical and more prediction experiments are necessary for improving the performance of analogue dynamical method. Meanwhile, the model predictable components should be reasonably obtained. These problems will be studied in further work.
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图 1 1 5d预报误差的相似指数随初值相似程度的演变
Fig. 1 The evolution of analogue index of forecast error with the analogue degree of initial value
图 2 2008年1月16日12：00及其4个最相似个例在η=7层 (约453hPa) 的24h温度场预报误差
Fig. 2 24-hour forecast error of temperature at η=7 (about 453 hPa) at 12: 00 16 January 2008 and its first 4 analogues
图 3 2008年1月16日12：00及其4个最相似个例估计的24h温度场预报误差
(η=4层，约216hPa; η=10层，约735hPa)
Fig. 3 24-hour forecast error of temperature at 12:00 16 January 2008 and its first 4 analogues
(η=4, about 216hPa; η=0, about 735 hPa)
图 4 5个个例平均的500hPa高度场的逐日预报与实况的距平相关系数 (a)，均方根误差 (b) 和500hPa温度场的逐日预报与实况的距平相关系数 (c)，均方根误差 (d)
Fig. 4 The daily ACC averaged over 5 cases of 500hPa geopotential height (a) andtemperature (c), and thedaily RMS Eaveraged over 5 cases of 500hPa geopotential height (b) and temperature (d)
表 1 起始个例预报误差与相似个例预报误差、系统误差的相似指数随预报时长的演变
Table 1 The evolution of analogue index of forecast error on initial case, analogue case and system error with leading time
表 2 两种相似选取方案估计的预报误差与实际预报误差相似指数随预报时长演变
Table 2 The comparison of the evolution of analogue index of estimated forecast error and real forecast error with leading time
表 3 5个个例平均的全球6~15d平均500hPa高度场和温度场的预报评分
Table 3 6—15-day average score of 5 cases of 500hPa geopotential height and temperature
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[1] Simmons A J,Hollingsworth A,Someaspects of the improve-ment in skill of numericalweather prediction,Quart J Roy Mete-orol Soc,2002,128:647-677. doi: 10.1256/003590002321042135 [2] 陈德辉,薛纪善,数值天气预报业务模式现状与展望,气象学报,2004,62(5):623-633. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXB200405009.htm [3] 丑纪范,谢志辉,王式功,建立6-15天数值天气预报业务系统的另类途径,军事气象水文,2006(3):4-9. [4] Lorenz E N,A study of the predictability of a 28-variable at-mospheric model,Tellus,1965,17:321-333. doi: 10.1111/tus.1965.17.issue-3 [5] Lorenz E N,Atmospheric predictability experiments with a large numerical model,Tellus,1982,34:505-513. doi: 10.1111/tus.1982.34.issue-6 [6] Ding R Q,Li J P,Nonlinear finite-time Lyapunov exponent and predictability,Physics Letters A,2007,364:396-400. doi: 10.1016/j.physleta.2006.11.094 [7] Mu M,Duan W S,Xu H,Applications of conditional nonlinear optimal perturbation in predictability study and sen-sitivity analysis of weather and climate,Advances in Atmospheric Sciences,2006,23:992-1002. doi: 10.1007/s00376-006-0992-3 [8] Glahn H R,Lowry D A,The use of model output statistics(MOS)in objective weather forecasting,Journal of Applied Meteorology,1972,11:1203-1211. doi: 10.1175/1520-0450(1972)011<1203:TUOMOS>2.0.CO;2 [9] Hamill T M,Whitaker J S,Probabilistic quantitative precipi-tation forecasts based on reforecast analogs:Theory and ap-plication,Monthly Weather Review,2006,134:3209-3229. doi: 10.1175/MWR3237.1 [10] 顾震潮,天气数值预报中过去资料的使用问题,气象学报,1958,29(3):176-184. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXB195803002.htm [11] 丑纪范,为什么要动力-统计相结合?--兼论如何结合,高原气象,1986,5(4):367-372. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX198604008.htm [12] 郑庆林,杜行远,使用多时刻观测资料的数值天气预报新模式,中国科学a辑,1973,16(3):289-297. http://www.cnki.com.cn/Article/CJFDTOTAL-JAXK197303004.htm [13] 曹鸿兴,大气运动的自忆性方程,中国科学b辑,1993,23(1):104-112. http://www.cnki.com.cn/Article/CJFDTOTAL-JBXK199301014.htm [14] 封国林,曹鸿兴,谷湘潜,一种提高数值模式时间差分计算精度的新格式--回溯时间积分格式,应用气象学报,2002,13(2):207-217. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20020227&flag=1 [15] 陈伯民,纪立人,杨培才,改善月动力延伸预报水平的一种新途径,科学通报,2003,48(5):513-520. http://www.cnki.com.cn/Article/CJFDTOTAL-KXTB200305021.htm [16] 曹鸿兴,谷湘潜,自忆谱模式制作中期天气预报的试验,应用气象学报,2000,11(4):455-466. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20000467&flag=1 [17] 邱崇践,丑纪范,天气预报的相似-动力方法,大气科学,1989,13(1):22-28. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXK198901002.htm [18] 黄建平,王绍武,相似-动力模式的季节预报试验,中国科学b辑,1991,21(2):216-224. http://www.cnki.com.cn/Article/CJFDTOTAL-JBXK199102013.htm [19] Huang J P,Yi Y H,Wang S W,Ananalogue-dynami-cal long-range numerical weather prediction system incorpora-ting historical evolution,Quarterly Journal of the Royal Meteorological Society,1993,119:547-565. doi: 10.1002/(ISSN)1477-870X [20] 鲍名,倪允琪,丑纪范,相似-动力模式的月平均环流预报试验,科学通报,2004,49(11):1112-1115. http://www.cnki.com.cn/Article/CJFDTOTAL-KXTB200411017.htm [21] 丑纪范,任宏利,数值天气预报--另类途径的必要性和可行性,应用气象学报,2006,17(2):240-244. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20060240&flag=1 [22] Gao L,Ren H L,Li J P,Analogue correction method of errors and its application to numerical weather prediction,Chinese Physics,2006,15(4):882-889. doi: 10.1088/1009-1963/15/4/038 [23] 任宏利,张培群,李维京,基于多个参考态更新的动力相似预报方法及应用,物理学报,2006,55(8):4388-4396. http://www.cnki.com.cn/Article/CJFDTOTAL-WLXB200608100.htm [24] 张邦林,丑纪范,经验正交函数在气候数值模拟中的应用,中国科学b辑,1991,21(4):442-448. http://www.cnki.com.cn/Article/CJFDTOTAL-JBXK199104013.htm [25] 张培群,丑纪范,改进月延伸预报的一种方法,高原气象,1997,16(4):376-388. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX704.005.htm [26] 张邦林,丑纪范,经验正交函数展开精度的稳定性研究,气象学报,1992,50(3):342-345. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXB199203009.htm [27] 董敏,国家气侯中心大气环流模式--基本原理和使用说明,北京:气象出版社,2001:5-15. [28] Danforth C M,Kalnay E,Miyoshi T,Estimating and correc-ting global weather model error,Monthly Weather Review,2007,135(2):281-299. doi: 10.1175/MWR3289.1 [29] 任宏利,封国林,张培群,论动力相似预报的物理基础问题,地球科学进展,2007,22(10):1027-1035. http://www.cnki.com.cn/Article/CJFDTOTAL-DXJZ200710005.htm -
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