Concentric Eyewall Typhoon characteristics at Western North Pacific

We develop an objective method to detect the typhoons with concentric eyewall (CE) structure using the passive microwave satellite SSM/I and TMI imageries. Fourteen years of data with 91 CE typhoons from 1997 to 2010 are studied. Exclude the typhoons with centers within 200 km from the land, we identify three types of CE structure change: the typical eye replacement cycle (ERC: 53%), the concentric eyewall maintained (CEM: 23.5%) and no typical replacement cycle (NRC: 23.5%). The ERC type is the cases with dissipation of inner core within 20 hr after the CE structure formation. The CEM type is cases with the CE structure maintained for more than 20 hr (mean duration time is 31 hr for CEM typhoons). The NRC type is cases with only the dissipation of the outer eyewall. The intensity decline of NRC cases is usually faster than that of ERC cases after the CE formation. The CEM cases are with stronger intensity than that of ERC and NRC cases before and after the CE formation. The intensity of CEM cases is increasing continuously 18 hr after the CE structure formation and followed by a gradual intensity decrease. This intensity decrease of CEM is slower than that of ERC and NRC cases. It is found that most of the NRC cases occur in the higher latitude, in a relatively low sea surface temperature (approximately 27°C) and in a large vertical shear environment (7.5 ms-1 shear between 850 hPa and 200 hPa levels). The NRC cases on the average are with a larger northward translation speed of approximately 4.5 ms-1, which is much faster than that of CEM and ERC types (both approximately 2.6 ms-1). The CEM cases are often with a greater averaged intensity (63 ms-1) and a larger averaged moat size (56 km) than that of ERC and NRC cases (both have an averaged intensity and moat size of 57 ms-1 and 44 km respectively). In addition, the CEM cases are in a relative low vertical shear (5 ms-1 shear) and a relative high SST (approximately 29°C) environment. In all the CE cases, 50% variance of the moat size is explained by the filamentation dynamics. In particular, large moat width of CE typhoons usually are with small core size or large intensity.