| 经验正交函数展开气象场收敛性的研究 |
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| 引用本文： | 丁裕国,吴息.经验正交函数展开气象场收敛性的研究[J].热带气象学报,1988(4):316-326. |
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| 作者姓名： | 丁裕国 吴息 |
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| 作者单位： | 南京气象学院
(丁裕国)，南京气象学院(吴息) |
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| 摘 要： | 本文从理论上证明,一个气象场的总方差可分解为代表气象场基本特征的信号场方差和代表随机干扰的随机场方差两部分。研究表明,若给定气象场总方差,则当噪声场方差强时,信号场方差必较弱,反之亦然。在此基础上,论证了经验正交函数(记为EOF_3)收敛速度的影响因素,指出EOF_3用于气象场时,其收敛于原始场的速度取决于场的联合熵及场内各站点的个别熵敛两方面因素,并以前者为主。在标准化情况下,上述因素等价于气象场本身的相关结构和场内空间分布变动程度对收敛速度的影响。文中提出对任一气象场资料应用EOF_3方法时,预估其收敛速度的几种经验性判据。分析表明,这些判据的应用效果很好。
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| 收稿时间： | 1987/8/22 0:00:00 |
| 修稿时间： | 1987/10/16 0:00:00 |
STUDIES OF CONVERGENCE FOR THE EXPANSION OF METEOROLOGICAL FIELDS WITH EMPIRICAL ORTHOGONAL FUNCTIONS |
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| Ding Yuguo and Wu Xi.STUDIES OF CONVERGENCE FOR THE EXPANSION OF METEOROLOGICAL FIELDS WITH EMPIRICAL ORTHOGONAL FUNCTIONS[J].Journal of Tropical Meteorology,1988(4):316-326. |
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| Authors: | Ding Yuguo and Wu Xi |
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| Institution: | Nanjing Institute of Meteorology;Nanjing Institute of Meteorology |
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| Abstract: | In this paper,it is shown theoretically that the total variance of a meteorological field is composed of two parts: the variance of the signal field which represents the fundamental characteristics of the meteorological field and the variance of the noise field which represents the random turbulence. It is found that with the total van ance of the meteorological field given, the variance of the noise field will be weakl when the variance of the signal field is gstrong and vice versa. On this basis, the influencing factors of the convergence speed are demonstrated for Empirical Orthogonal Functions (EOFs). When the EOFs are applied to the meteorological field, it is noted that the speed of convergence in the original field depends upon the factors of both the joint entropies of the field and the individual entropies at the stations in the field. The former is proved to be the main factor.According to standardization, these factors are equivalent to the effects of both the correlation structure of the meteorological field and the variation of the spatial distribution in the field on the convergence speed. Several empirical criteria are presented for the estimation of the convergence speed when the EOFs are applied to any original field. Tests show that these criteria are very effective in meteorological field analysis. |
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