Fig. 4: Changes in annual-mean latitude of tropical cyclone all-track-points, and changes in three seasonality components, over the extended period 1951–2018.

a Timeseries of annual-mean latitude of all-track-points (black), and timeseries of peak-season (July–September; JAS, blue) and late-season (October–December; OND, red) relative frequencies of all-track-points in the year, in two epochs (the pre-satellite era 1951–1978 and the satellite era 1979–2018) of the whole period 1951–2018, in the Best Track ensemble mean. b Decompositions of annual-mean latitude of all-track-points by three seasonality contributing components, representing the effects of departures (from the respective time means) of monthly relative frequency (\({\delta }_{{P}^{{\prime} }}\), black), monthly latitude (\({\delta }_{{{\mathrm Lat}}^{{\prime} }}\), blue) and the covariance of the two terms (\({\delta }_{{P}^{{\prime} }{{\mathrm {Lat}}}^{{\prime} }}\), red), respectively, in two epochs of the whole period 1951–2018 in the Best Track ensemble mean. Dashed lines represent the linear trend, with shading showing 95% confidence interval for the linear fit; the El Niño Southern Oscillation and Pacific Decadal Oscillation effects are removed by a multivariate regression; latitude is converted to distance from the equator (km).