Global climatology of tropical cyclone size as inferred from QuikSCAT data

ABSTRACT This paper presents to date the most complete global climatology of the size of tropical cyclones (TCs) between 1999 and 2009 using the QuikSCAT satellite data. Here, TC size is defined as the azimuthal mean radius of 17 m s−1 surface winds from the TC centre. While the TC size climatology for the Western North Pacific (WNP) and North Atlantic (NA) has been documented in previous studies, those for the Eastern North Pacific (ENP), South Indian Ocean (SI) and South Pacific (SP) have yet to be examined in detail, which is the objective of this study. Among all the basins, TCs over the WNP are the largest and have the largest variance, while those over the ENP are the smallest. In addition, TCs in the Northern Hemisphere (WNP, NA and ENP) have two seasonal size peaks, but those in the Southern Hemisphere (SI and SP) have only one. An important finding is that for all basins, the size of a TC does not necessarily increase with latitude monotonically, but reaches the maximum at some latitudinal region. Such a result agrees well with a recent theoretical study in terms of a balance between the inertial stability associated with the TC circulation and the import of angular momentum into the TC.