Probabilistic assessment of storm surge potential due to explosive cyclogenesis in the northwest Pacific region

Abstract

Extratropical cyclones that develop rapidly in the northwest Pacific Ocean, called explosive cyclones, have caused storm surges twice recently along the coast of Nemuro Bay, located in northeastern Japan, in 2014 and 2015. As the number and intensity of explosive cyclones have increased over the last three decades near the Japanese archipelago (Iwao, Inatsu, and Kimoto 2012), the frequency of extreme storm surges is anticipated to increase under future climatic conditions. Explosive cyclones formed in the northwest Pacific region can be categorized into three major types (Yoshida and Asuma 2004) based on their evolution: Type-I cyclones develop over the Sea of Japan and travel toward the Sea of Okhotsk, Type-II are generated on the continent and move toward the Pacific Ocean through the Sea of Japan, and Type-III travel northward in the Pacific Ocean along the Japanese archipelago. We performed computational experiments of past storm surges to find statistical fea-tures of local sea levels, depending on the types of the cyclone evolution under a realistic meteorological scenario of winter cyclones, with aim to provide possible sea level rise expected in the northeast Asia.Here, we show that amplification of local sea level, governed by the orientation of coastal lines with cyclone tracks, is defined by the evolution type that is classified by their trajectories, rather than the intensity, of the cyclone. Nemuro Bay is the most vulnerable site in the northwest Pacific region regardless of the evolution type; thus repeated disasters are anticipated therein. Severe storm surges are also expected along certain other semi-enclosed coasts facing the northern Sea of Japan and Sea of Okhotsk due to Type-I cyclones. The probabilistic evaluation of sea levels depending on the cyclone evolution type as introduced in this study may be useful for evaluating potential disasters.

Tropical cyclone movement features in the western North Pacific region based on multi‐dimensional statistical analyses

“…The abovementioned discussions for TC movement only consider the zonally averaged data and lose sight of the F I G U R E 4 Variations of (a) semimajor axis, (b) semiminor axis, (c) included angle and (d) rotation angle of 50% probability elliptical envelope against latitude variations of TC movement against longitude and the corresponding spatial distribution, it is hence difficult to analyse on a specific area by relatively low-dimensional statistical approaches. In order to understand more detailed and comprehensive individual features (rather than average-based analysis), the complete twodimensional statistical analysis of TCs properties in the WNP is conducted with respect to the 1 × 1 latitude and longitude grids, as also used in Saruwatari et al (2019). The corresponding results are shown in Figures 5 and 6 for CMA and JMA datasets, respectively.…”

Climatological Features of Strong Winds Caused by Extratropical Cyclones around Japan

“…Moreover, since the cyclone-induced strong winds are responsible for high waves (Kita et al 2018;Saruwatari et al 2019) and drifting snow (Kawano and Kawamura 2018), these are involved in the occurrence of various natural disasters in Japan. Thus, it is important that we understand the features of strong winds associated with extratropical cyclones around Japan.…”