NASVD方法(noise-adjusted singular value decomposition)是一种基于多元统计分析来降低测量固有噪声的数据处理方法,通过将多道航空γ能谱仪采集到的大量测点构成的谱线矩阵分解为若干特征向量,再舍弃仅反映噪声的部分特征向量,利用...NASVD方法(noise-adjusted singular value decomposition)是一种基于多元统计分析来降低测量固有噪声的数据处理方法,通过将多道航空γ能谱仪采集到的大量测点构成的谱线矩阵分解为若干特征向量,再舍弃仅反映噪声的部分特征向量,利用噪声较少的特征向量对谱线矩阵进行重组。重组后,谱线矩阵中提取出的钾、铀、钍窗的计数率噪声均显著降低。笔者主要通过一些实际测区数据的处理结果来讨论聚类NASVD方法在不同情况测区的实际降噪效果。使用该方法分别对不同比例尺及飞行高度的实际测量数据进行了成图处理,并对处理结果进行了比较。在小比例尺航空γ能谱测量中,本方法优势并不十分显著。但在大比例尺,低高度的测量中,NASVD方法在空间分辨上较传统简单滤波方法有着非常明显的优势。展开更多
Ionospheric peak value of F2 layer （NmF2） is an important parameter in the ionosphere, which has important applications in short-wave communication, ionospheric modeling and so on. In this paper, the empirical ortho...Ionospheric peak value of F2 layer （NmF2） is an important parameter in the ionosphere, which has important applications in short-wave communication, ionospheric modeling and so on. In this paper, the empirical orthogonal function （EOF） decompo- sition method is used to analyze the NmFz obtained from the occultation data. Daily spatial distribution of NmF2 at the same time is relatively even. Variance of first modal is much larger than the other modals. A local wavelet power spectrum （LWPS） method is applied to analysis the cycle of Flo.7 index and time coefficient of first modal. The result shows that they have simi- lar cycle distribution, indicating that Flo.7 index is the main factor affecting variation of NmF〉 A function is established be- tween the tine coefficient of first modal and F10.7 index, average F10.7 index value of early 81 days fp by least squares method. The results show that contribution coefficient offp is negative which indicates that fp has an inert effect existing in the iono- sphere. Contribution coefficient of F10.7 is positive, which is consistent with the fact that it has an anomaly in winter/spring seasons. In summary, it is feasible to establish a mid-latitude empirical NmF2 model in northern hemisphere based on occulta- tion data and EOF decomposition method.展开更多
文摘NASVD方法(noise-adjusted singular value decomposition)是一种基于多元统计分析来降低测量固有噪声的数据处理方法,通过将多道航空γ能谱仪采集到的大量测点构成的谱线矩阵分解为若干特征向量,再舍弃仅反映噪声的部分特征向量,利用噪声较少的特征向量对谱线矩阵进行重组。重组后,谱线矩阵中提取出的钾、铀、钍窗的计数率噪声均显著降低。笔者主要通过一些实际测区数据的处理结果来讨论聚类NASVD方法在不同情况测区的实际降噪效果。使用该方法分别对不同比例尺及飞行高度的实际测量数据进行了成图处理,并对处理结果进行了比较。在小比例尺航空γ能谱测量中,本方法优势并不十分显著。但在大比例尺,低高度的测量中,NASVD方法在空间分辨上较传统简单滤波方法有着非常明显的优势。
基金supported by the National Natural Science Foundation of China(Grant No.40505005)the Specialized Research Fund for State Key Laboratories(Grant No.Y22612A33S)
文摘Ionospheric peak value of F2 layer （NmF2） is an important parameter in the ionosphere, which has important applications in short-wave communication, ionospheric modeling and so on. In this paper, the empirical orthogonal function （EOF） decompo- sition method is used to analyze the NmFz obtained from the occultation data. Daily spatial distribution of NmF2 at the same time is relatively even. Variance of first modal is much larger than the other modals. A local wavelet power spectrum （LWPS） method is applied to analysis the cycle of Flo.7 index and time coefficient of first modal. The result shows that they have simi- lar cycle distribution, indicating that Flo.7 index is the main factor affecting variation of NmF〉 A function is established be- tween the tine coefficient of first modal and F10.7 index, average F10.7 index value of early 81 days fp by least squares method. The results show that contribution coefficient offp is negative which indicates that fp has an inert effect existing in the iono- sphere. Contribution coefficient of F10.7 is positive, which is consistent with the fact that it has an anomaly in winter/spring seasons. In summary, it is feasible to establish a mid-latitude empirical NmF2 model in northern hemisphere based on occulta- tion data and EOF decomposition method.
