  The use of multitaper estimates for spectral proper orthogonal decomposition
(SPOD) is explored. Multitaper and multitaper-Welch estimators that use
discrete prolate spheroidal sequences (DPSS) as orthogonal data windows are
compared to the standard SPOD algorithm that exclusively relies on weighted
overlapped segment averaging, or Welch's method, to estimate the cross-spectral
density matrix. Two sets of turbulent flow data, one experimental and the other
numerical, are used to discuss the choice of resolution bandwidth and the
bias-variance tradeoff. Multitaper-Welch estimators that combine both
approaches by applying orthogonal tapers to overlapping segments allow for
flexible control of resolution, variance, and bias. At additional computational
cost but for the same data, Multitaper-Welch estimators provide lower variance
estimates at fixed frequency resolution or higher frequency resolution at
similar variance compared to the standard algorithm.
