Fig. 2: Latitudinal migration of tropical and polar circulation boundaries.

a–d, The time series of the deseasonalized monthly anomalies in the latitudinal positions of Lat_U0 for the NH and the SH (a,b) and Lat_U_max for the NH and the SH (c,d). The solid lines across the data series are the least-squares regression lines with their colour matching their corresponding data series, although they are largely overlapping. The slope and its uncertainty (95% CI) for each fitting line are given in the legends, as well as its P value. The insets show the mean monthly values of the latitudinal positions averaged over the 2000–2020 period for each of the three datasets. Data: MISR CMV (version F02_0002)¹⁰ and ERA5 reanalysis data¹².