The monthly peak-to-peak seasonal cycle amplitudes of TC PI in each main development region (excluding NI) and the percent change in the TC PI term amplitude when either the disequilibrium or efficiency term is linearly removed [following Eq. (2)]. A negative amplitude indicates the seasonal cycle maximizes in the austral summer. A positive percentage change indicates that the term climatologically damps the TC PI seasonal cycle, whereas a negative percentage indicates that the term amplifies the TC PI seasonal cycle on average. Values are calculated using MERRA-2 data from 1980 to 2013.