The Effects of Orography on the Extratropical Transition of Tropical Cyclones: A Case Study of Typhoon Sinlaku (2008)

Abstract

Extratropical transition (ET) can cause high-impact weather in midlatitude regions and therefore constitutes an ongoing threat at the end of a tropical cyclone’s (TC) life cycle. Most of the ET events occur over the ocean, but some TCs recurve and undergo ET along coastal regions; however, the latter category is less investigated. Typhoon Sinlaku (2008), for example, underwent ET along the southern coast of Japan. It was one of the typhoons that occurred during the T-PARC field campaign, providing unprecedented high-resolution observational data. Sinlaku is therefore an excellent case to investigate the impact of a coastal region, and in particular orography, on the evolution of ET. Here, observations from T-PARC are employed to verify high-resolution simulations of Sinlaku. In addition, a sensitivity simulation is performed with the orography of Japan removed. The presence of orography causes blocking of low-level, cool midlatitude air north of Japan. Without this inflow of cool air, ET is delayed. Only once Sinlaku moves away from the orographic barrier does the cool, dry environmental air penetrate equatorward, and ET continues. On a local scale, evaporatively cooled air from below Sinlaku’s asymmetric precipitation field could be advected toward the cyclone center when orography was favorable for it. Changes in the vortex structure, as known from mature TCs interacting with orography, were only minor due to the high translation speed during ET. This study corroborates that orography can impact ET by modulating both the synoptic-scale environmental conditions and the mesoscale cyclone structure during ET.

Tropical cyclone effects enhance limnetic plankton trophic‐level relationships in a subtropical oligotrophic freshwater ecosystem

“…Notably, in this study, a moderate TC duration significantly weakened the plankton trophic‐level relationships at the surface depth, which might pose challenges for plankton to recover quickly. We thus speculated that the weak associations between plankton trophic‐level relationships and TC disturbance ranking in this study might be additionally caused by orographic effects, which mountain slopes that surround the FTR might modulate TC effects on the reservoir catchment (Lentink et al., 2018; Minamide & Yoshimura, 2014; Whitford & Duval, 2020). Moreover, TCs can promote trophic‐level relationships both through bottom‐up and top‐down controls in plankton communities (Byrnes et al., 2011; Chen et al., 2020; Hoover et al., 2006).…”

温帯低気圧化中の台風Hagibis (2019)の北側に集中した降水の複合的な力学

“…As the orography around Japan (Fig. 2a) may affect vertical motion and precipitation of TCs (Murata 2009;Lentink et al 2018), we also conducted a sensitivity experiment in which Honshu, Hokkaido, Shikoku, Kyushu and other neighboring small islands were replaced by the ocean surface with no orography (contours in Fig. 3b, c).…”

Cluster Analysis Tailored to Structure Change of Tropical Cyclones Using a Very Large Number of Trajectories

“…COSMO is a nonhydrostatic limited-area model for fully compressible flow, which has been designed for both operational numerical weather prediction and scientific applications. Besides in Euler et al (2019), convection-permitting COSMO simulations have been successfully used before to investigate structure changes of a TC during ET (Lentink et al 2018).…”