Multitaper spectral analysis of atmospheric radar signals

Abstract

Abstract. Multitaper spectral analysis using sinusoidal taper has been carried out on the backscattered signals received from the troposphere and lower stratosphere by the Gadanki Mesosphere-Stratosphere-Troposphere (MST) radar under various conditions of the signal-to-noise ratio. Comparison of study is made with sinusoidal taper of the order of three and single tapers of Hanning and rectangular tapers, to understand the relative merits of processing under the scheme. Power spectra plots show that echoes are better identified in the case of multitaper estimation, especially in the region of a weak signal-to-noise ratio. Further analysis is carried out to obtain three lower order moments from three estimation techniques. The results show that multitaper analysis gives a better signal-to-noise ratio or higher detectability. The spectral analysis through multitaper and single tapers is subjected to study of consistency in measurements. Results show that the multitaper estimate is better consistent in Doppler measurements compared to single taper estimates. Doppler width measurements with different approaches were studied and the results show that the estimation was better in the multitaper technique in terms of temporal resolution and estimation accuracy.

Latitude dependency of solar flare index–temperature relation occuring over middle and high latitudes of Atlantic–Eurasian region

“…We used here three sinusoidal tapers. Such a method has been previously and successfully used for the analysis of climate time series of different time scale and resolution (Ghil and Vautard, 1991;Yiou et al, 1996;Ghil et al, 2002;Anandan et al, 2004;Kilcik et al, 2008;Vaquero et al, 2010). Since this method is now standard, and can be found elsewhere, we do not describe it here.…”

Error estimation of spectral parameters for high-resolution wind and turbulence measurements by wind profiler radars

“…Though the MTM degrades the Doppler velocity resolution, it can reduce the spectrum perturbations without degrading the time resolution because the Doppler spectra produced by the orthogonal tapers have independent spectrum perturbations. Anandan et al [] reported that the MTM can improve echo detection in low SNR conditions.Because a huge amount of data needs to be processed in RIM measurements, we used the moment method. For methods that require iterations to calculate the spectral parameters (e.g., the least squares method), initial values of all the P , V d , and σ 3dB values and thresholds to finish the iterations must be determined.…”

“…Though the MTM degrades the Doppler velocity resolution, it can reduce the spectrum perturbations without degrading the time resolution because the Doppler spectra produced by the orthogonal tapers have independent spectrum perturbations. Anandan et al [2004] reported that the MTM can improve echo detection in low SNR conditions. 3.…”

Spectral Analysis of MST Radar Signal using Maximum Likelihood Estimation Algorithm

“…This method has some parameters were utilized to adaptively fallow the radar signal within the range-Doppler spectral frame. Bi-spectral estimation [2] and Multi taper spectral estimation [3] is used to radar signal, which include broadened spectral peak and high computational cost respectively. Other algorithms like cepstral thresholding [4], wavelet-based denoising [5] and PCA approach [6] are also applied to spectrum estimation of the MST data.…”