Impacts of SST Patterns on Rapid Intensification of Typhoon Megi (2010)

Abstract

Typhoon Megi (2010), a very intense tropical cyclone with a minimum central pressure of 885 hPa, was characterized by especially rapid intensification. We investigated this intensification process by a simulation experiment using a high‐resolution (0.02° × 0.02°) three‐dimensional atmosphere‐ocean coupled regional model. We also performed a sensitivity experiment with a time‐fixed sea surface temperature (SST). The coupled model successfully simulated the minimum central pressure of Typhoon Megi, whereas the fixed SST experiment simulated an excessively low minimum central pressure of 839 hPa. The simulation results also showed a close relationship between the radial SST profiles and the rapid intensification process. Because the warm sea increased near‐surface water vapor and hence the convective available potential energy, the high SST in the eye region facilitated tall and intense updrafts inside the radius of maximum wind speed and led to the start of rapid intensification. In contrast, high SST outside this radius induced local secondary updrafts that inhibited rapid intensification even if the mean SST in the core region exceeded 29.0°C. These secondary updrafts moved inward and eventually merged with the primary eyewall updrafts. Then the storm intensified rapidly when the high SST appeared in the eye region. Thus, the changes in the local SST pattern around the storm center strongly affected the rapid intensification process by modulating the radial structure of core convection. Our results also show that the use of a high‐resolution three‐dimensional atmosphere‐ocean coupled model offers promise for improving intensity forecasts of tropical cyclones.

Radial Distributions of Sea Surface Temperature and Their Impacts on the Rapid Intensification of Typhoon Hato (2017)

“…The major cooling, peaking at approximately −1.7 • C, appears to the rhs of the track from around 117.0 • E longitude to the edge of continental shelf and is roughly parallel to the shelf break. Such right-hand-side cooling is usually associated with a strong and fast-moving typhoon, as was suggested in earlier studies [8,27,36]. SST over the shallow continental shelf barely cooled, which is also similar to the observations.…”

“…According to the sensitive experiments that conducted by Halliwell et al [26], small TCs with fast translation speed tend to be less sensitive to the SST changes, owing to the small eyewall coverage of the specific water and insufficient response time. However, Kanada et al [27] suggested that even weak local SST responses could affect the inner-core structure and intensity evolution in TCs by altering the CAPE and moisture distributions. SST distributions also impact the intensification rate of TCs.…”

Variations in extreme wave events near a South Pacific Island under global warming: case study of Tropical Cyclone Tomas

“…Moreover, Nasuno et al (2016) showed that small latent heating differences over the ocean can delay the development of TCs. Kanada et al (2017b) indicated that sea surface cooling can suppress the delayed evolution of the simulated TCs. However, it is not the main scope of this study to improve the boundary condition (SSTs) and surface physics schemes.…”

“…Although the time profile of the simulated central pressure appears to be delayed for approximately 1 day compared with that of the best track data, the simulated profile reasonably captures the decreasing slope and minimum central pressure of the best track data. Several studies have shown delayed intensification of simulated TCs (Oku et al 2010;Takayabu et al 2015;Nasuno et al 2016;Kanada et al 2017b;Nayak and Takemi 2019). Takayabu et al (2015) indicated the effect of initial and boundary conditions on TC simulations.…”

An Evaluation of COAMPS-TC Real-Time Forecasts for Super Typhoon Nepartak (2016)

“…It is well established by previous studies that warmer SSTs are correlated with TCs that undergo RI. Although Kanada et al (2017) suggested that the RI is sensitive to the SST pattern, the SST at the storm center is used here as a basic and more independent (of storm size) diagnostic. Figure 5 shows time series of SST and the value of 200 -850-hPa vertical wind shear at the storm center following with the storm movement along the forecast time.…”