Extreme tropical cyclone activities in the southern Pacific Ocean

Abstract

ABSTRACTThis research concerning the South Pacific Ocean shows the 10‐year and interannual variability of extreme cyclones (categories 4 and 5). The intensity of these cyclones has been reanalysed on the basis of GMS, GOES and NOAA satellite images with the Dvorak technique. In the period 1980–2016, 63 cyclones reached categories 4 and 5. During the decade 1980–1989, the intensity of cyclones of at least 115 knots over 1 min (100 knots over 10 min used by the meteorological centres in the South Pacific) was underestimated: we found 19 such cyclones, as opposed to 11 in IBTrACS, and 6 in the SPEArTC and in the Joint Typhoon Warning Center (JTWC) databases. Between 1980 and 2016, the number of extreme cyclones did not show any tendency to increase. The 1983 season was the most active, with six cyclones of categories 4 and 5 that do not figure in the JTWC database for the South Pacific. Only one intense cyclone has been reported in the SPEArTC and five cyclones in IBTrACS in 1983. El Niño episodes concurred with a much higher number of cyclones of at least 115 knots than La Niña episodes. More than half of the category 5 (at least 140 knots) cyclones were observed during El Niño years. The South Pacific Ocean is the theatre of very intense cyclones, comparable to those in the western or eastern North Pacific. Thus, by reanalysing satellite images, an intensity of 170 knots was attributed to cyclone Hina (March 1985), which was probably one of the strongest in the southern hemisphere since 1980.