ESTIMATION ERROR OF SPECTRAL PARAMETERS OF MESOSPHERE-STRATOSPHERE-TROPOSPHERE RADARS OBTAINED BY LEAST-SQUARES FITTING METHOD AND ITS LOWER BOUND
ESTIMATION ERROR OF SPECTRAL PARAMETERS OF MESOSPHERE-STRATOSPHERE-TROPOSPHERE RADARS OBTAINED BY LEAST-SQUARES FITTING METHOD AND ITS LOWER BOUND
复制标题
DOI：
10.1029/rs023i006p01013
复制
发表时间：
1988-11-01
期刊：
影响因子：
1.6
通讯作者：
KATO, S
中科院分区：
文献类型：
--
作者：
YAMAMOTO, M;SATO, T;KATO, S
利用最小二乘拟合和矩量法的计算机模拟方法，计算了中间层-平流层-对流层（MST）雷达回波功率谱参数的估计误差。最小二乘拟合方法被证明是优于矩量法在低信噪比（SNR）的区域，特别是对于窄光谱。然而，在无穷大时，拟合方法的估计误差大约是矩量法的两倍。这归因于功率谱密度的统计涨落的性质，其显示χ 2分布。对于这两种方法在无穷大，我们推导出的方程，显示的准确性的估计与观测周期和光谱宽度。当我们使用MU雷达（46.5 MHz）观测数据的拟合方法时，平流层和中间层径向风速的典型误差分别为0.7和2.0 m s-1。通过对谱线的对数进行无限次拟合，使多普勒频移的误差比矩量法小20倍左右。它已被证明，这是一种技术，以实现理论下限的估计。
We have calculated the estimation error of parameters of echo power spectra observed by mesosphere‐stratosphere‐troposphere (MST) radars by means of computer simulations for least squares fitting and moment methods. The least squares fitting method is shown to be better than the moment method in the region with low signal‐to‐noise ratio (snr), especially for narrow spectra. However, the estimation error of the fitting method at infinite snr is approximately twice that of the moment method. This has been attributed to the nature of the statistical fluctuation of the power spectral density, which shows a χ2distribution. For both methods at infinite snr we have derived equations which show the accuracy of the estimates versus observation period and spectral width. When we use the fitting method for the data observed with the MU radar (46.5 MHz), the typical errors of the radial wind velocities are 0.7 and 2.0 m s−1in the stratosphere and in the mesosphere, respectively. By calculating the logarithm of the spectrum with inifite snr and fitting a parabolic curve to it, the error of the Doppler shift has become approximately 20 times smaller than that of the moment method. It has been shown that this is one technique to achieve the theoretical lower bound of the estimates.