On tropical cyclone size and intensity changes associated with two types of long-lasting rainbands in monsoonal environments

Abstract

Tropical cyclones (TCs) in a monsoonal environment may have heavy rain events separate from the eyewall rainfall. Two types of long-lasting rainbands in western North Pacific TCs interacting with the East Asia summer monsoon during 1999–2009 are identified and the effects of these rainbands on TC size and intensity changes are examined. For all of the south-type Outer Mesoscale Convective Systems as defined in our previous study, the TC intensification rate is decreased but the rate of size change is not modified. Long-lasting south-type Enhanced Rainbands (ERBs) that develop between 100 and 300 km radii and move cyclonically are associated with significant TC size increases. Seventy percent of very large typhoons had an ERB during the period when they intensified from tropical storms to typhoons.