Size Characteristics of Tropical Cyclones Affecting East China and Those in the Western North Pacific

This study investigates the size characteristics and related temporal variations of tropical cyclones (TCs) over the Western North Pacific (WNP) and those affecting East China (EC) using Joint Typhoon Warning Center (JTWC) data during 2001−20. The average size of EC TCs is found to be similar to that over the WNP. Furthermore, the annual maximum lifetime maximum size (LMS) of EC TCs shows a statistically significant increasing trend, implying a more severe impact on the EC region. Composite analyses of intensity and size variation over the entire lifetime of TCs, before and after re-curvature, and before and after rapid intensification (RI), show that there are significant differences between them in some key areas: (1) The intensity begins to rapidly decrease after the TC has reached its highest intensity, but the size remains quasi-constant; (2) When a TC recurves south of 15°N or north of 30°N, the variation trend for both intensity and size are broadly similar before and after curvature, but their variation trends are opposite when the recurvature occurs between 15°−30°N; (3) After RI, the intensity reaches its peak value within 24 h, whereas the size reaches its LMS after 30−48 h. A significant correlation is also found between the rate of change in intensity and that of size during the development stage, with a correlation coefficient of 0.67 and 0.73 for TCs in the WNP and EC, respectively. However, no significant correlation exists during the weakening stage.