- Research Letter
- Open Access
Interdecadal variation of Korea affecting TC activity in early 1980s
© The Author(s) 2017
Received: 26 October 2016
Accepted: 7 January 2017
Published: 19 January 2017
By performing a statistical change-point analysis of activities of the tropical cyclones (TCs) that have affected Korea (K-TCs), it was found that there was a significant change between 1983 and 1984. During the period of 1984–2004 (P2), more TCs migrated toward the west, recurved in the southwest, and affected Korea, compared to the period of 1965–1983 (P1). These changes for P2 were related to the southwestward expansion of the subtropical western Pacific high (SWPH) and, simultaneously, elongation of its elliptical shape toward Korea. Because of these changes, the central pressure and lifetime of K-TC during P2 were deeper and longer, respectively, than figures for P1. This stronger K-TC intensity for P2 was related to the more southwestward genesis due to the southwestward expansion of the SWPH. The weaker vertical wind shear environment during P2 was more favorable for K-TC to maintain a strong intensity in the mid-latitudes of East Asia.
Many factors, including SST, vertical wind shear, thermodynamic instability/stability, upper-tropospheric momentum flux convergence, mid-tropospheric moisture, and so on have an influence on tropical cyclone (TC) activity (Gray 1968; Molinari and Vollaro 1989; Pfeffer and Challa 1992; DeMaria et al. 2001; Goldenberg et al. 2001; Baik and Paek 2001). In particular, TC movement and intensity in the subtropics or mid-latitudes are greatly influenced by environmental circulation systems, such as the location and strength of the subtropical western Pacific high (SWPH).
Chan and Shi (1996) fit the TC annual frequency in the Northwest Pacific into a second-order polynomial equation and observed that it has been increasing since 1994. Chu and Clark (1999) showed that the annual frequency of TCs was increasing in the central North Pacific. Kamahori et al. (2006) stressed that we must prepare against the effects of strong TCs because intense TC days have been increasing steadily for the last 30 years. Elsner et al. (2008) suggested similarly that the intensity of strong TCs is increasing in all TC basins except the South Pacific Ocean basin, and that this increase was particularly evident in the North Atlantic and north Indian Ocean basins. Tu et al. (2009) showed that TC frequency over the Taiwan-East China Sea region has been increasing since 2000 because of northward shift of TC track over western North Pacific (WNP)–East Asian region. Landsea et al. (1996) claimed that the frequency of intense hurricanes in the Atlantic had been decreasing for the previous 50 years. Ho et al. (2004) proved through a statistical change-point analysis that the annual frequency of TCs in the East China Sea had been decreasing since the mid-1970s and that the decreasing trend was more distinct around the Philippines. As an extension of the study by Chan and Shi (1996) after analyzing TC-frequency data for the Northwest Pacific that had been updated through the early 2000s, Chan (2005) showed that the frequency of TCs had actually decreased since the mid-1990s. Chan also observed this decreasing trend in the annual frequency of TCs in the South China Sea over the prior 40 years.
Gong and Ho (2002) demonstrated that the SWPH has enlarged, intensified, and shifted southwestward in recent years, which gives rise to an anticyclonic circulation anomaly over the region from the South China Sea to the western Pacific, and thus causes wet anomalies over the Yangtze River valley. Ho et al. (2004) also showed that this southwestward expansion of the SWPH from the late 1970s leads to a decrease in TC passage frequency in the East China Sea, but to an increase in the South China Sea. In addition, they suggested that this change in the SWPH resulted in the westward shift of the recent major TC tracks and therefore contributed to a larger elliptic pathway of TC migration. On the contrary, Choi and Kim (2007) demonstrated that both frequency and intensity of a TC at landfall in the Korean Peninsula have rapidly increased since the late 1980s. In particular, they showed that the frequency of TC with intensity greater than tropical storm (34 kts ≤ maximum sustained wind speed ≤ 47 kts) has increased remarkably and suggested that this result is because a SWPH tend to retreat eastward in recent years.
On the other hand, in relation to the interdecadal variations in the climate of the summer climate, Inoue and Matsumoto (2007) showed that in the early 1980s, there were shifts not only in TC activity around Japan, but also in the entire large-scale circulation pattern over East Asia and the western North Pacific (WNP). Therefore, it was known that except for variation of Korean Peninsula landfalling TC, most of the climate changes associated with the activity of the SWPH in the aforementioned studies occurred between late 1970s and early 1980s. In fact, climate regime shift in the later 1970s or the early 1980s occurred not only in East Asia but also in the seas and air over the Pacific, and thus related various studies were accumulated (e.g., Nitta and Hu 1996; Niebauer 1998; Chang et al. 2000; Stephens et al. 2001; Bond et al. 2003; Wu et al. 2005; Ye and Hsieh 2006).
In the South China Sea and Western Pacific region, previous study also identifies a decadal shift of the TC activity in the early 1990s (Yang et al. 2012). Yang et al. (2012) has found that the South China Sea has more TCs during 1994–2008. They also attributed it to the eastward migration of SWPH, lower wind shear, higher mid-level humidity as well as warmer upper ocean conditions (sea surface temperature and upper ocean heat content). Another relevant study suggested that the wind shear, humidity, and vorticity related to monsoon variation and Indian Ocean Basin mode might be the cause of the change of TC activity over the western Pacific (Du et al. 2011). Xie et al. (2016) summarized the relationship of the East Asia Climate and climate modes in the tropical Indo-Pacific and proposed that the Indo-western Pacific ocean capacitor (IPOC) mode dominates the interannual and decadal climate over the region.
This study also found that a climate shift related to TC activity affecting Korea exists in the early 1980s. Thus, we first analyzed the interdecadal changes on the activity of the TC affecting Korea and then their relation to atmospheric circulation patterns in East Asia and the WNP regions.
Data and methods
The present study used the TC best track dataset archived by the Regional Specialized Meteorological Center (RSMC)—Tokyo (http://www.jma.go.jp/en/typh/). This dataset includes TC measurements at 6-h intervals of latitude–longitude and intensity, including central pressure (hPa) and maximum sustained wind speed (MSWS; kt). A TC that affected Korea (hereafter, K-TC) was defined as one that passed through the area of 32°–40°N, 120°–138°E (Korea Meteorological Administration 1996; boxes in Fig. 2) for July–September. Based on this definition, 156 TCs were selected for the period of 1965–2004 (40 years). The reasons that the current study covered the period of 1965–2004 are as follows: Choi and Moon (2012) demonstrated that using K-TC frequency during summer (June–September), and significant regime shifts occurred in 2004, as well as in the mid-1960s and mid-1980s. Choi and Kim (2007) showed that K-TC frequency had increased rapidly since the early-2000s and that the increase in the frequency of intense K-TC was more obvious. Their analysis showed that the reason for the increase was that the SWPH shifted to the east, resulting in the TC track moving to the east and reducing the frequency of TCs passing through mainland China before making landfall on the Korean Peninsula.
The TC intensity was divided into 5 stages on the basis of the intensity of the MSWS: tropical depression (TD; MSWS < 34 kts), tropical storm (TS; 34 kts ≤ MSWS ≤ 47 kts), severe tropical storm (STS; 48 kts ≤ MSWS ≤ 63 kts), typhoon (TY; MSWS ≥ 64 kts), and extratropical cyclone (EC). Storms at the TD and EC stages were included in the K-TC activity, because these storms cause tremendous damage in the mid-latitude countries of East Asia, such as China, Korea, and Japan (Kitabatake 2002).
On the other hand, we defined a K-TC recurving location as the point where a TC’s direction of movement changes from a westward to an eastward movement. Also, to define the K-TC passage frequency, TC position was binned into the corresponding 5° × 5° grid box and even if the same TC entered the same grid box multiple times, it was only counted once.
We also used the 6-h measurements of geopotential height (gpm), horizontal wind (m s−1), air temperature (°C), and relative humidity (%) reanalyzed by the National Center for Environmental Prediction–the National Center for Atmospheric Research (NCEP–NCAR) to characterize the large-scale circulation patterns related to the decadal variation in the K-TC activity (Kalnay and Coauthors 1996; Kistler and Coauthors 2001). These data are available on a 2.5° × 2.5° grid at standard pressure levels.
The NOAA Extended Reconstructed monthly Sea Surface Temperature (SST) (Reynolds et al. 2002), available from the same organization, was also used. The data have a horizontal resolution of 2.0° × 2.0° latitude–longitude and are available for the period of 1854 to the present day.
Meanwhile, while TC data are accessible for the period from 1951 to the present, the reliability of TC data in the 1950s and early 1960s prior to the weather satellite era could lead to problems (Ho et al. 2005). The NCEP–NCAR reanalysis data are also affected by two major changes in the observing system: upper air networks and satellite observations (Kistler and Coauthors 2001). To avoid any possible impact of unreliable data on the present results, all calculations are confined to the period from 1965 to 2004, during which weather satellites are used.
Here, u and v indicate the zonal and meridional flows, respectively. 200 and 850 represent 200 and 850-hPa levels, respectively.
The composite analysis is average for the months of the K-TC activity, and an anomalous map was obtained by subtracting the climatological summer (July, August, and September; JAS) mean during the period of 1965–2004 from the average for the months of K-TC activity. Here, JAS is defined as the seasons that the K-TC activity is the most active Park et al. (2006)
Shift between 1983 and 1984
TC Frequency and recurving location
Generally, TCs tend to migrate along the western periphery of the SWPH. The recurving location of K-TCs may also change because of this recent shift in the SWPH. In relation to the change in the latitude of the recurving location, 34 of the 52 TCs (65.4%) that recurved in P1 recurved to the north of 30°N, while just 26 of the 77 TCs (33.7%) that recurved in P2 did so. In other words, about 70% of all the K-TCs that recurved during P2 recurved to the south of 30°N. Therefore, it can be concluded that K-TCs tended to recurve to the north of 30°N during P1 and to the south of 30°N during P2. On the other hand, in relation to the change in longitude, while only 7 of the 52 TCs for P1 recurved to the west of 120°E, 28 of the 77 TCs for P2 did so. Although the number of TCs that recurved to the west of 120°E is not very high for either period, the number of TCs that recurved to the west of 120°E for P2 is about four times that of P1. Also, in order to examine whether there was a significant change in the recurving location of K-TCs, we applied the time series of the latitude and longitude portions of the recurving locations to the CPA, respectively (Fig. 1b, c). Dramatically, this shows that there is clear change point between 1983 and 1984 for the two variables, just as with the TC frequency. The average recurving location for P1 is 31.2°N, 124.6°E and it is 27.6°N, 121.8°E for P2. Therefore, we can objectively confirm through the CPA that the recurving location of K-TCs has been shifted more southwestward since 1984.
Vertical wind shear difference between P1 and P2
Eventually, it is concluded that the VWS in most regions of East Asia and the WNP is generally weaker for P2 than for P1. Thus, we can confirm that the period of P2 shows the potential for a TC to maintain a strong intensity in the mid-latitudes of East Asia.
After this study investigates other environmental fields, favorable conditions for TC intensification around Korea, such as anomalous warm sea surface temperature and warm air temperature, and anomalous high relative humidity are shown during P2 (not shown).
Summary and conclusions
The change-point analysis (CPA) was performed for tropical cyclone (TC) activities that affected Korea (K-TC) during the period of 1965–2004. As a result, we suggest that there is a clear shift in K-TC activities between 1983 and 1984 as follows: There were 95 TCs for the period of 1984–2004 (P2) and only 61 for the period of 1965–1983 (P1). The tracks and recurving locations of these TCs shifted more westward and southwestward in P2, respectively. This recent shift in K-TC activities was related to the southwestward expansion of the subtropical western Pacific high (SWPH) and, simultaneously, its elliptic shape toward Korea.
Associated with the K-TC intensity, the central pressure of the TCs near Korea also showed a difference between the 2 years. That is, the average central pressure for P2 was about 10 hPa deeper than that for P1. This was because the TCs during P2 occurred further to the southeast because of the recent southwestward expansion of the SWPH and, therefore, had a longer lifetime than those for P1. The cause of this difference in the TC intensity between the two periods was well confirmed through a vertical wind shear (VWS) analysis. The VWS for P2 was weaker over most regions of East Asia and the western North Pacific (WNP) than that for P1. Eventually, it could be determined that the period of P2 had a greater potential for a K-TC to maintain a strong intensity in the mid-latitudes of East Asia.
However, the increased typhoon activity that occurred in/around Korea starting in 1984 was not reflected basinwide (WNP). Yumoto and Matsuura (2001) and Matsuura et al. (2003) noted in common that the annual frequency of TCs in the WNP is high in the 1960s, low in the 1970s, and again high in the 1980s with a gradual increasing trend.
JWC designed and carried out the study and wrote the paper. YC provided detailed information on East Asian meteorological data. JYK acquired and processed the data of YC. JWC, YC, and JYK contributed extensively to the scientific discussion. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
This work was supported by the R&D Project of the Korea Meteorological Administration “Development and application of technology for weather forecast.”
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- Baik JJ, Paek JS (2001) Relationship between vertical wind shear and typhoon intensity change, and development of three predictor intensity prediction model. J Meteorol Soc Japan 79:695–700View ArticleGoogle Scholar
- Bond NA, Overland JE, Spillane M, Stabeno P (2003) Recent shifts in the state of the North Pacific. Geophys Res Lett. doi:10.1029/2003GL018597 Google Scholar
- Chan JCL (2005) Interannual and interdecadal variations of tropical cyclone activity over the western North Pacific. Meteorol Atmos Phys 89:143–152View ArticleGoogle Scholar
- Chan JCL, Shi JE (1996) Long-term trends and interannual variability in tropical cyclone activity over the western north Pacific. Geophys Res Lett 23:2765–2767View ArticleGoogle Scholar
- Chang CP, Zhang Y, Li T (2000) Interannual and interdecadal variations of the East Asian summer monsoon and tropical Pacific SSTs. Part II: the meridional structure of the monsoon. J Clim 13:4326–4340View ArticleGoogle Scholar
- Chen TC, Weng SP, Yamazaki N, Kiehne S (1998) Interannual variation in the tropical cyclone formation over the western North Pacific. Mon Weather Rev 126:1080–1090View ArticleGoogle Scholar
- Choi KS, Kim BJ (2007) Climatological characteristics of tropical cyclones making landfall over the Korean Peninsula. J Korean Meteo Soc 43:97–109Google Scholar
- Choi KS, Moon IJ (2012) Changes in tropical cyclone activity that has affected Korea since 1999. Nat Hazards 62:971–989View ArticleGoogle Scholar
- Chu PS (2002) Large-scale circulation features associated with decadal variations of tropical cyclone activity over the central North Pacific. J Clim 15:2678–2689View ArticleGoogle Scholar
- Chu PS, Clark JD (1999) Decadal variations of tropical cyclone activity over the Central North Pacific. Bull Am Meteorol Soc 80:1875–1881View ArticleGoogle Scholar
- DeMaria M, Knaff JA, Connell BH (2001) A tropical cyclone genesis parameter for the tropical Atlantic. Weather Forecast 16:219–233View ArticleGoogle Scholar
- Du Y, Yang L, Xie SP (2011) Tropical Indian Ocean influence on Northwest Pacific tropical cyclones in summer following strong El Niño. J Clim 24:315–322View ArticleGoogle Scholar
- Elsner JB, Jagger T, Niu XF (2000) Changes in the rates of North Atlantic major hurricane activity during the 20th century. Geophys Res Lett 27:1743–1746View ArticleGoogle Scholar
- Elsner JB, Kossin JP, Jagger TH (2008) The increasing intensity of the strongest tropical cyclones. Nature 455:92–95View ArticleGoogle Scholar
- Goldenberg SB, Landsea CW, Mestas-Nunez AM, Gray WM (2001) The recent increase in Atlantic hurricane activity: causes and implications. Science 293:474–479View ArticleGoogle Scholar
- Gong DY, Ho CH (2002) Shift in the summer rainfall over the Yangtze River valley in the late 1970s. Geophys Res Lett 29(10):78-1–78-4. doi:10.1029/2001GL014523 View ArticleGoogle Scholar
- Gray WM (1968) Global view of the origin of tropical disturbances and storms. Mon Weather Rev 96:669–700View ArticleGoogle Scholar
- Gray WM (1975) Tropical cyclone genesis. Atmospheric Sciences Paper No. 234. Colorado State University, Fort CollinsGoogle Scholar
- Ho CH, Baik JJ, Kim JH, Gong DY (2004) Interdecadal changes in summertime typhoon tracks. J Clim 17:1767–1776View ArticleGoogle Scholar
- Ho CH, Kim JH, Kim HS, Sui CH, Gong DY (2005) Possible influence of the Antarctic Oscillation on tropical cyclone activity in the western North Pacific. J Geophys Res 110:D19104. doi:10.1029/2005JD005766 View ArticleGoogle Scholar
- Inoue T, Matsumoto J (2007) Abrupt climate changes observed in late August over central Japan between 1983 and 1984. J Clim 20:4957–4967View ArticleGoogle Scholar
- Kalnay E, Coauthors (1996) The NCEP/NCAR 40-year reanalysis project. Bull Am Meteorol Soc 77:437–471View ArticleGoogle Scholar
- Kamahori H, Yamazaki N, Maanji N, Takahashi K (2006) Variability in intense tropical cyclone days in the western North Pacific. Sola 2:104–107View ArticleGoogle Scholar
- Kistler R, Coauthors (2001) The NCEP–NCAR 50-year reanalysis: monthly means CD-ROM and documentation. Bull Am Meteorol Soc 82:247–267View ArticleGoogle Scholar
- Kitabatake N (2002) Extratropical transformation of typhoon Vicki (9807): structure change and the role of upper-tropospheric disturbances. J Meteorol Soc Japan 80:229–247View ArticleGoogle Scholar
- Korea Meteorological Administration (1996) Typhoon white book. Korea Meteorological Administration, SeoulGoogle Scholar
- Landsea CW, Nicholls N, Gray WM, Avilia LA (1996) Downward trends in the frequency of intense Atlantic hurricanes during the past five decades. Geophys Res Lett 23:1697–1700View ArticleGoogle Scholar
- Matsuura T, Yumoto M, Iizuka S (2003) A mechanism of interdecadal variability of tropical cyclone activity over the western North Pacific. Clim Dyn 21:105–117View ArticleGoogle Scholar
- McBride JL, Zehr R (1981) Observational analysis of tropical cyclone formation, Part II: comparison of non-developing versus developing systems. J Atmos Sci 38:1132–1151View ArticleGoogle Scholar
- Molinari J, Vollaro D (1989) External influences on hurricane intensity. Part I: outflow layer eddy angular momentum fluxes. J Atmos Sci 46:1093–1105View ArticleGoogle Scholar
- Niebauer HJ (1998) Variability in Bering Sea ice cover as affected by a regime shift in the North Pacific in the period 1947–1996. J Geophys Res 103:27717–27737View ArticleGoogle Scholar
- Nitta T, Hu ZZ (1996) Summer climate variability in China and its association with 500 hPa height and tropical convection. J Meteorol Soc Japan 74:425–445Google Scholar
- Park JK, Kim BS, Jung WS, Kim EB, Lee DG (2006) Change in statistical characteristics of typhoon affecting the Korean Peninsula. Atmosphere 16:1–17Google Scholar
- Pfeffer RL, Challa M (1992) The role of environmental asymmetries in Atlantic hurricane formation. J Atmos Sci 49:1051–1059View ArticleGoogle Scholar
- Reynolds RW, Rayner NA, Smith TM, Stokes DC, Wang W (2002) An improved in situ and satellite SST analysis for climate. J Clim 15:1609–1625View ArticleGoogle Scholar
- Stephens CS, Levitus S, Antonov J, Boyer TP (2001) On the Pacific Ocean regime shift. Geophys Res Lett 28:3721–3724View ArticleGoogle Scholar
- Tu JY, Chou C, Chu PS (2009) The abrupt shift of typhoon activity in the vicinity of Taiwan and its association with Western North Pacific-East Asian climate change. J Clim 22:3617–3628View ArticleGoogle Scholar
- Wang B, Chan JCL (2002) How strong ENSO events affect tropical storm activity over the western North Pacific. J Clim 15:1643–1658View ArticleGoogle Scholar
- Wu L, Lee DE, Liu Z (2005) The 1976/1977 North Pacific climate regime shift: the role of subtropical ocean adjustment and coupled ocean-atmosphere feedback. J Clim 18:5125–5140View ArticleGoogle Scholar
- Xie SP, Kosaka Y, Du Y, Hu K, Chowdary JS (2016) Indo-western Pacific ocean capacitor and coherent climate anomalies in post-ENSO summer: a review. Adv Atmos Sci. doi:10.1007/s00376-015-5192-6 Google Scholar
- Yang L, Du Y, Xie S, Wang D (2012) An inter-decadal change of tropical cyclone activity in the South China Sea in early 1990s. Chin J Oceanol Limnol 30:138–144Google Scholar
- Ye Z, Hsieh WW (2006) The influence of climate regime shift on ENSO. Clim Dyn 26:823–833View ArticleGoogle Scholar
- Yumoto M, Matsuura T (2001) Interdecadal variability of tropical cyclone activity in the western North Pacific. J Meteorol Soc Japan 79:23–35View ArticleGoogle Scholar