Perform a localized multitaper cross-spectral analysis using using arbitrary windows derived from a mask.
call SHMultiTaperMaskCSE (mtse
, sd
, sh1
, lmax1
, sh2
, lmax2
, tapers
, lmaxt
, k
, taper_wt
, norm
, csphase
, exitstatus
)
mtse
: output, real(dp), dimension (lmax
-lmaxt
+1)
: The localized multitaper cross-power spectrum estimate. lmax
is the smaller of lmax1
and lmax2
.
sd
: output, real(dp), dimension (lmax
-lmaxt
+1)
: The standard error of the localized multitaper cross-power spectral estimates. lmax
is the smaller of lmax1
and lmax2
.
sh1
: input, real(dp), dimension (2, lmax1
+1, lmax1
+1)
: The spherical harmonic coefficients of the first function.
lmax1
: input, integer
: The spherical harmonic bandwidth of sh1
.
sh2
: input, real(dp), dimension (2, lmax2
+1, lmax2
+1)
: The spherical harmonic coefficients of the second function.
lmax2
: input, integer
: The spherical harmonic bandwidth of sh2
.
tapers
: input, real(dp), dimension ((lmaxt
+1)**2, k
)
: An array of the k
windowing functions, arranged in columns, obtained from a call to SHReturnTapersMap
. The spherical harmonic coefficients are packed according to the conventions in SHCilmToVector
.
lmaxt
: input, integer
: The spherical harmonic bandwidth of the windowing functions in the array tapers
.
k
: input, integer
: The number of tapers to be utilized in performing the multitaper spectral analysis.
taper_wt
: input, optional, real(dp), dimension (k
)
: The weights used in calculating the multitaper spectral estimates and standard error. Optimal values of the weights (for a known global power spectrum) can be obtained from the routine SHMTVarOpt
.
norm
: input, optional, integer, default = 1
: 1 (default) = 4-pi (geodesy) normalized harmonics; 2 = Schmidt semi-normalized harmonics; 3 = unnormalized harmonics; 4 = orthonormal harmonics.
csphase
: input, optional, integer, default = 1
: 1 (default) = do not apply the Condon-Shortley phase factor to the associated Legendre functions; -1 = append the Condon-Shortley phase factor of (-1)^m to the associated Legendre functions.
exitstatus
: output, optional, integer
: If present, instead of executing a STOP when an error is encountered, the variable exitstatus will be returned describing the error. 0 = No errors; 1 = Improper dimensions of input array; 2 = Improper bounds for input variable; 3 = Error allocating memory; 4 = File IO error.
SHMultiTaperMaskCSE
will perform a localized multitaper cross-spectral analysis of two input functions expressed in spherical harmonics, SH1
and SH2
, using an arbitrary set of windows derived from a mask. The maximum degree of the localized multitaper power spectrum estimate is lmax-lmaxt
, where lmax
is the smaller of lmax1
and lmax2
. The matrix tapers
contains the spherical harmonic coefficients of the windows and can be obtained by a call to SHReturnTapersMap
. The coefficients of each window are stored in a single column, ordered according to the conventions used in SHCilmToVector
.
If the optional array taper_wt
is specified, then these weights will be used in calculating a weighted average of the individual k
tapered estimates (mtse
) and the corresponding standard error of the estimates (sd
). If not present, the weights will all be assumed to be equal. When taper_wt
is not specified, the mutltitaper spectral estimate for a given degree will be calculated as the average obtained from the k
individual tapered estimates. The standard error of the multitaper estimate at degree l is simply the population standard deviation, S = sqrt(sum (Si - mtse)^2 / (k-1))
, divided by sqrt(k
). See Wieczorek and Simons (2007) for the relevant expressions when weighted estimates are used.
The employed spherical harmonic normalization and Condon-Shortley phase convention can be set by the optional arguments norm
and csphase
; if not set, the default is to use geodesy 4-pi normalized harmonics that exclude the Condon-Shortley phase of (-1)^m.
Wieczorek, M. A. and F. J. Simons, Minimum-variance multitaper spectral estimation on the sphere, J. Fourier Anal. Appl., 13, doi:10.1007/s00041-006-6904-1, 665-692, 2007.