The intensity of tropical cyclones(TCs)varies at different rates throughout their life cycle.Among them,rapid intensification(RI,intensity change≥30 knots/24 h)and rapid weakening(RW,intensity change≤30 kn...The intensity of tropical cyclones(TCs)varies at different rates throughout their life cycle.Among them,rapid intensification(RI,intensity change≥30 knots/24 h)and rapid weakening(RW,intensity change≤30 knots/24 h)of TCs are extremely difficult to predict.Despite numerous studies,the RI and RW of TC continue to cause forecasting errors.Considering the increasing frequency of RI/RW cases,studying the variations of short-period(6-h)intensity changes occurring within RI/RW events can help us better understand RI/RW events.We used the International Best Track Archive for Climate Stewardship(IBTrACS)global TC dataset(1981–2020)to study how variations in 6-h intensity changes relate to trends in RI&RW events.Generally,the 24-h RI(RW)events are built upon 6-h intensity changes with a magnitude of 10 kt(10 kt).In the last two decades,this magnitude has increased to 15 kt(15 kt)and,in rarer events,up to 55 kt in 6-h.This increase explains the rise in stronger RI/RW events.Importantly,even non-RI and non-RW events now more frequently exhibit 6-h intensity changes of magnitude±10 kt,thereby increasing the likelihood of TCs transitioning into RI/RW phases.As a result,the upward trends in RI and RW events measured over a 24-h period are largely explained by the amplification of the upward trends in 6-h intensity changes with increasing measuring interval.It is found that even minor TCs(cyclones which do not reach higher intensities during their lifetime)are also growing at an increased intensification rate at 6-h interval,which was not observed/reported at 24-h intensity changes.This has led to a decrease in the average duration of the intensification phase,which has decreased at a rate of 0.67-h per year between 1981 and 2020.These findings can help forecasters identify early signs of rapid intensity changes,enabling more timely and accurate warnings in a changing climate.展开更多
基金the Institution of Eminence(IoE)-University of Hyderabad(UoH)for providing financial support(Sanction No:UoH-IoERC5-22-025)for carrying out the present work.
文摘The intensity of tropical cyclones(TCs)varies at different rates throughout their life cycle.Among them,rapid intensification(RI,intensity change≥30 knots/24 h)and rapid weakening(RW,intensity change≤30 knots/24 h)of TCs are extremely difficult to predict.Despite numerous studies,the RI and RW of TC continue to cause forecasting errors.Considering the increasing frequency of RI/RW cases,studying the variations of short-period(6-h)intensity changes occurring within RI/RW events can help us better understand RI/RW events.We used the International Best Track Archive for Climate Stewardship(IBTrACS)global TC dataset(1981–2020)to study how variations in 6-h intensity changes relate to trends in RI&RW events.Generally,the 24-h RI(RW)events are built upon 6-h intensity changes with a magnitude of 10 kt(10 kt).In the last two decades,this magnitude has increased to 15 kt(15 kt)and,in rarer events,up to 55 kt in 6-h.This increase explains the rise in stronger RI/RW events.Importantly,even non-RI and non-RW events now more frequently exhibit 6-h intensity changes of magnitude±10 kt,thereby increasing the likelihood of TCs transitioning into RI/RW phases.As a result,the upward trends in RI and RW events measured over a 24-h period are largely explained by the amplification of the upward trends in 6-h intensity changes with increasing measuring interval.It is found that even minor TCs(cyclones which do not reach higher intensities during their lifetime)are also growing at an increased intensification rate at 6-h interval,which was not observed/reported at 24-h intensity changes.This has led to a decrease in the average duration of the intensification phase,which has decreased at a rate of 0.67-h per year between 1981 and 2020.These findings can help forecasters identify early signs of rapid intensity changes,enabling more timely and accurate warnings in a changing climate.
