Multi-Taper Spectral Analysis

This script includes functions to compute the power spectrum of a signal and to perform a coherence analysis of two time-series using the multi-taper method. These are basically just Python versions of the Matlab functions available from Peter Huybers' website. Requires the spectrum Python module.

multi_taper_analysis.py

Eddy Flux Co-Spectra

Function for calculating eddy flux co-spectra, following method of Hayashi (1971) (see also Randel and Held (1991)). Includes functions to calculate space-time cross-spectra and phase-speed cross-spectrum.

eddy_co_spectra.py

"1-Dimensional" 2-layer QG Model

Stand-alone Python script for a "1-dimensional" 2-layer QG model described in Panetta and Held (1988). The model is truncated in wavenumber space to retain only the zonal-mean flow and one non-zero zonal wavenumber (the default set-up retains the most unstable wave) and can be quickly run on a laptop. Non-linear terms are de-aliased using the Orszag (1971) "two-thirds" rule. The domain is doubly-periodic and the model is forced by an unstable meridional temperature gradient and by lower-layer Ekman friction. Note that all variables are non-dimensionalized.

Trunc_2l_QG.py

Hovmuller diagram

Hovmuller diagram of the upper layer streamfunction from a simulation with the model.