INTERNATIONAL JOURNAL OF CLIMATOLOGY Int. J. Climatol. 30: 1472–1483 (2010) Published online 23 July 2009 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/joc.1986 Interdecadal variation of tropical cyclone making landfall over the Korean Peninsula Ki-Seon Choi, a Baek-Jo Kim, a Do-Woo Kim, b and Hi-Ryong Byun b * a Korea Meteorological Administration, Seoul, Republic of Korea b Department of Environmental Atmospheric Sciences, Pukyung National University, Busan, Republic of Korea ABSTRACT: The results from applying indices for the accumulated cyclone energy and the total movement to the change-point analysis showed that depending on the frequency of the tropical cyclone (TC) over the Korean Peninsula for the past 54 years, the results could be categorised into three different categories: High-frequency period-1 (1951–1965), low-frequency period (1966–1985), and high-frequency period-2 (1986–2004). During the second high-frequency period, there were three distinct recorded changes. First, compared to the other two periods, majority of the TC occurred in the southeastern regions. Second, the TC track and recurving location shifted to the east. Therefore, the total number of TCs passing mainland China had reduced whereas the number of TCs moving across the eastern shores of mainland China showed a relative increase. In addition, the key landing area on the Korean Peninsula shifted from the western coastlines to the southern coastlines. Third, the TC intensity increased, which could be attributed to the fact that the new TCs migrated over the sea rather than moving over mainland China. Finally, these series of changes resulted in the intensification of the monsoon trough in the eastern region compared to the other two periods, as well as the synoptic characteristics preventing the westward expansion of the western North Pacific high (WNPH). Copyright  2009 Royal Meteorological Society KEY WORDS interdecadal variation; tropical cyclone; change-point analysis; accumulated cyclone energy Received 18 March 2008; Revised 2 February 2009; Accepted 25 June 2009 1. Introduction A number of studies on interannual or interdecadal vari- ations of the tropical cyclone (TC) activity in each TC basin such as the Atlantic, the western North Pacific (WNP), and the central North Pacific were extensively carried out. They showed that the comparisons of atmo- spheric environments between the active and inactive periods of TC may give us important and useful sugges- tions by which we can forecast long-term activity of TC statistically. They also stressed that a better understand- ing of the mechanisms responsible for the interannual or interdecadal variations of TC activity may be helpful for the effective mitigation and reduction of TC disasters. However, the temporal variation of a TC activity in each TC basin or globe has still remained controversial. Lighthill et al. (1994) noted that there is no apparent vari- ation in the annual number of TC in the North Atlantic or in the northeast and northwest Pacific basins. Klotzbach (2006) also pointed out that there has been no significant increasing trend in accumulated cyclone energy (ACE) in each TC basin except for only a small increase in Cate- gory 4–5 hurricanes (114–135 kts and >135 kts, respec- tively, according to Saffir – Simpson Hurricane scale) over * Correspondence to: Hi-Ryong Byun, Department of Environmental Atmospheric Sciences, Pukyong National University, Daeyeon 3-Dong Nam-Gu, Busan 608-737, Republic of Korea. E-mail: hrbyun@pknu.ac.kr the past 20 years (1990–2006), in spite of the increas- ing trend in sea surface temperature for the same period. However, Landsea et al. (1996) showed that there is an obvious decreasing trend in the frequency of intense hur- ricanes in the Atlantic during the past five decades. On the contrary, Chan and Shi (1996), Chu and Clark (1999), and Clark and Chu (2002) showed that the change of TC activity in the WNP and central Pacific basins has increased since the 1980s. Emanuel (2005) also found out that the maximum sustained wind speed has increased by approximately 50% in both the Atlantic basin and the WNP basin since the mid 1970s using a power dissipation index (PDI). Webster et al. (2005), from the analysis of Category 4–5 hurricanes for all TC basins over the past 30 years, indicated that comparing to an earlier period (1975–1989), their numbers have nearly doubled in a more recent 15-year period (1990–2004). In particular, Goldenberg et al. (2001) showed that in the North Atlantic basin, the period of 1995–2000 experienced the highest level of hurricane activity. In addition, they stressed that this highest hurricane activity results from simultaneous increases in North Atlantic SST and decreases in vertical wind shear and then this trend of hurricane activity may persist for several decades. Finally, it has been stated in some studies that there are clear fluctuations in TC activity in each decade. Lander (1994), Yumoto and Matsuura (2001), and Matsuura et al. (2003) noted in common that the annual frequency of TCs Copyright  2009 Royal Meteorological Society