Geophysical Applications of Partial Wavelet Coherence and Multiple Wavelet Coherence

In this paper, the application of partial wavelet coherence (PWC) and multiple wavelet coherence (MWC) to geophysics is demonstrated. PWC is a technique similar to partial correlation that helps identify the resulting wavelet coherence (WTC) between two time series after eliminating the influence of their common dependence. MWC, akin to multiple correlation, is, however, useful in seeking the resulting WTC of multiple independent variables on a dependent one. The possible El Nino-Southern Oscillation-related impact of the large-scale atmospheric factors on tropical cyclone activity over the western North Pacific is used as an example. A software package for PWC and MWC has been developed. It also includes modified software that rectified the bias in the wavelet power spectrum and wavelet cross-spectrum. The package is available online (see http://www.cityu.edu.hk/gcacic/wavelet).