a, Link distance distributions for the December–January–February season are shown for the following cases: considering only links within the tropics (green squares), links within the tropics and to the extratropics of both hemispheres (magenta diamonds), links connecting the tropics and the extratropics of both hemispheres (cyan stars), links within the Northern Hemisphere (NH; upward red triangles) and links within the Southern Hemisphere (SH; downward blue triangles). b, Same as a, but for the JJA season. The distance distributions for all links taken together (as in Fig. 2) are indicated by black circles in both panels. We note that the super-power-law part of the distribution (that is, the part of the distribution for distances longer than 2,500 km) is substantially suppressed if the analysis is restricted to the global tropics (green squares), whereas it remains strong if links to the extratropics are included (magenta diamonds). In particular, the super-power-law part is much more pronounced if only the links connecting the tropics with the extratropics are considered, compared with the distribution of all links (black circles). We also note that the distributions are very similar for both seasons.