[Seminar on July 4] Variability and Changes in Northwest Pacific Typhoon Intensity
Dr. Wei Mei
University of North Carolina
10am, July 4, 2018
Room 319, Building 40, IAP
While of great concern to East and Southeast Asian countries, intensity changes in Northwest Pacific typhoons are poorly known owing to inconsistencies among different data sets. We have developed a new bias-corrected intensity dataset and studied both basin-integrated and regional typhoon intensity. We show that over the past six decades upper ocean temperatures in the low-latitude northwestern Pacific (LLNWP) and sea surface temperatures in the central equatorial Pacific control the basin-integrated typhoon intensity by setting the rate and duration of typhoon intensification, respectively. An anomalously strong LLNWP upper ocean warming has favored increased intensification rates and led to unprecedentedly high average typhoon intensity during the recent global warming hiatus period, despite a reduction in intensification duration tied to the central equatorial Pacific surface cooling.
We further show that the recent intensification has mostly occurred to typhoons that make landfall, which have intensified by 12–15% with the proportion of storms of categories 4 and 5 having doubled or even tripled. In contrast, typhoons that stay over the open ocean have experienced only modest changes. The increased intensity of landfalling typhoons is due to strengthened intensification rates, which in turn are tied to locally enhanced ocean surface warming on the rim of East and Southeast Asia.