Consistent Pattern of Rainfall Asymmetry in Binary Tropical Cyclones

Abstract The rainfall distribution in a tropical cyclone (TC) is affected by many factors/processes. Most of previous studies have focused on individual TCs. Little is known about the rainfall distribution in binary TCs. This study examines the rainfall distribution in binary TCs over the western North Pacific based on the observational data. When two TCs become nearby, the asymmetric component of rainfall shows an increasing trend with rainfall significantly suppressed in Quadrant IV of the TC located to the west when orienting the two TCs in the west‐east direction. The suppression becomes remarkable once the separation distance between the two TCs is within about 2,050 km. Furthermore, the convective activity in one TC is related to the deep‐layer vertical wind shear (VWS) from its companion. Rainfall is enhanced downshear‐left in a TC, consistent with a single TC embedded in an environmental VWS as found in previous studies.