IntegratedSNR: Frequency-dependent signal-to-noise ratio from integrated...

In EarthSystemDiagnostics/proxysnr: Separate Signal and Noise in Climate Proxy Records

Description

This function calculates the signal-to-noise ratio (SNR) as a function of frequency, interpreted as the temporal resolution of a proxy record. This variant of the SNR is obtained from the ratio of a signal and a noise spectrum, which are integrated before cumulatively across frequencies.

Usage

IntegratedSNR(
  input,
  N = 1,
  f1 = 2,
  f2 = "max",
  freq.cut.lower = NULL,
  freq.cut.upper = NULL
)

Arguments

input	a list of the spectral objects lists signal and noise, usually to be obtained from a call to SeparateSpectra
N	integer; number of proxy records averaged. The default returns the SNR assuming a single proxy record. For a different number, the SNR is scaled by this number, assuming independent noise between the records.
f1	index of the the minimum frequency from which to integrate the signal and noise spectra for calculating the SNR; per default the lowest frequency of the spectral estimates is omitted
f2	index of the maximum frequency until which to integrate the signal and noise spectra for calculating the SNR; defaults to use the maximum frequency of the given spectral estimates
freq.cut.lower	lower frequency (not index!) at which to cut the spectra: this provides a direct way for specifying a minimum frequency for the integration different from the minimum frequency of the spectral estimates. Setting freq.cut.lower overrides the frequency corresponding to the index set in f1.
freq.cut.upper	upper frequency (not index!) at which to cut the spectra: this provides a direct way for specifying a maximum frequency for the integration different from the maximum frequency of the spectral estimates. Setting freq.cut.upper overrides the frequency corresponding to the index set in f2.

Details

The function is an implementation of Eq. (6) in Münch and Laepple (2018). The integral in (6) is approximated by the cumulative sum of the integration arguments from f.int1 to f.int2, where f.int1 = f1 and f.int2 consecutively increases from f1 to f2.

Value

a spectral object list of the SNR.

Author(s)

Thomas Münch

References

Münch, T. and Laepple, T.: What climate signal is contained in decadal- to centennial-scale isotope variations from Antarctic ice cores? Clim. Past, 14, 2053–2070, https://doi.org/10.5194/cp-14-2053-2018, 2018.

EarthSystemDiagnostics/proxysnr documentation built on Oct. 2, 2021, 3:03 p.m.