• Adams, J. B., M. E. Mann, and C. M. Ammann, 2003: Proxy evidence for an El Niño-like response to volcanic forcing. Nature, 426, 274278.

    • Search Google Scholar
    • Export Citation
  • Altman, D. G., 1991: Practical Statistics for Medical Research. Chapman and Hall/CRC, 611 pp.

  • Ashok, K., S. K. Behera, S. A. Rao, H. Weng, and T. Yamagata, 2007: El Niño Modoki and its possible teleconnection. J. Geophys. Res., 112, C11007, doi:10.1029/2006JC003798.

    • Search Google Scholar
    • Export Citation
  • Bjerknes, J., 1969: Atmospheric teleconnections from the equatorial Pacific. Mon. Wea. Rev., 97, 163172.

  • Camargo, S. J., and A. H. Sobel, 2005: Western North Pacific tropical cyclone intensity and ENSO. J. Climate, 18, 29963006.

  • Camargo, S. J., A. H. Sobel, A. G. Barnston, and K. A. Emanuel, 2007: Tropical cyclone genesis potential index in climate models. Tellus, 59A, 428443.

    • Search Google Scholar
    • Export Citation
  • Chan, J. C. L., 1984: An observational study of the physical processes responsible for tropical cyclone motion. J. Atmos. Sci., 41, 10361048.

    • Search Google Scholar
    • Export Citation
  • Chan, J. C. L., 1985: Tropical cyclone activity in the northwest Pacific in relation to the El Niño/Southern Oscillation phenomena. Mon. Wea. Rev., 113, 599606.

    • Search Google Scholar
    • Export Citation
  • Chan, J. C. L., 2005: The physics of tropical cyclone motion. Annu. Rev. Fluid Mech., 37, 99128.

  • Chan, J. C. L., 2008: Decadal variations of intense typhoon occurrence in the western North Pacific. Proc. Roy. Soc., Math. Phys. Eng. Sci., 464, 249272.

    • Search Google Scholar
    • Export Citation
  • Chan, J. C. L., and W. M. Gray, 1982: Tropical cyclone movement and surrounding flow relationships. Mon. Wea. Rev., 110, 13541374.

  • Chan, J. C. L., and M. Xu, 2009: Inter-annual and inter-decadal variations of landfalling tropical cyclones in East Asia. Part I: Time series analysis. Int. J. Climatol., 29, 12851293.

    • Search Google Scholar
    • Export Citation
  • Chan, J. C. L., K. Liu, S. E. Ching, and E. S. T. Lai, 2004: Asymmetric distribution of convection associated with tropical cyclones making landfall along the South China coast. Mon. Wea. Rev., 132, 24102420.

    • Search Google Scholar
    • Export Citation
  • Chen, G., and C.-Y. Tam, 2010: Different impacts of two kinds of Pacific Ocean warming on tropical cyclone frequency over the western North Pacific. Geophys. Res. Lett., 37, L01803, doi:10.1029/2009GL041708.

    • Search Google Scholar
    • Export Citation
  • Chia, H. H., and C. Ropelewski, 2002: The interannual variability in the genesis location of tropical cyclones in the northwest Pacific. J. Climate, 15, 29342944.

    • Search Google Scholar
    • Export Citation
  • Chu, P.-S., 2002: Large-scale circulation features associated with decadal variations of tropical cyclone activity over the central North Pacific. J. Climate, 15, 26782689.

    • Search Google Scholar
    • Export Citation
  • Chu, P.-S., 2004: ENSO and tropical cyclone activity. Hurricanes and Typhoons: Past, Present, and Potential, R. J. Murnane and K.-B. Liu, Eds., Columbia Press, 297–332.

  • Fudeyasu, H., S. Iizuka, and T. Matsuura, 2006: Impact of ENSO on landfall characteristics of tropical cyclones over the western North Pacific during the summer monsoon season. Geophys. Res. Lett., 33, L21815, doi:10.1029/2006GL027449.

    • Search Google Scholar
    • Export Citation
  • Goh, Z.-C. A., and J. C. L. Chan, 2010: An improved statistical scheme for the prediction of tropical cyclones making landfall in South China. Wea. Forecasting, 25, 587593.

    • Search Google Scholar
    • Export Citation
  • Gray, W. M., 1979: Hurricanes: Their formation, structure and likely role in the tropical circulation. Meteorology over the Tropical Oceans, D. B. Shaw, Ed., Roy. Meteor. Soc., 155–218.

  • Harr, P. A., and R. L. Elsberry, 1991: Tropical cyclone track characteristics as a function of large-scale circulation anomalies. Mon. Wea. Rev., 119, 14481468.

    • Search Google Scholar
    • Export Citation
  • Harr, P. A., and R. L. Elsberry, 1995a: Large-scale circulation variability over the tropical western North Pacific. Part I: Spatial patterns and tropical cyclone characteristics. Mon. Wea. Rev., 123, 12251246.

    • Search Google Scholar
    • Export Citation
  • Harr, P. A., and R. L. Elsberry, 1995b: Large-scale circulation variability over the tropical western North Pacific. Part II: Persistence and transition characteristics. Mon. Wea. Rev., 123, 12471268.

    • Search Google Scholar
    • Export Citation
  • Ho, C.-H., H.-S. Kim, J.-H. Jeong, and S.-W. Son, 2009: Influence of stratospheric quasi-biennial oscillation on tropical cyclone tracks in the western North Pacific. Geophys. Res. Lett., 36, L06702, doi:10.1029/2009GL037163.

    • Search Google Scholar
    • Export Citation
  • Holland, G. J., 1993: Tropical cyclone motion. Global Guide to Tropical Cyclone Forecasting, G. Holland, Ed., WMO, 3.1–3.46.

  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77, 437471.

  • Kim, H.-M., P. J. Webster, and J. A. Curry, 2009: Impact of shifting patterns of Pacific Ocean warming on North Atlantic tropical cyclones. Science, 325, 77 80.

    • Search Google Scholar
    • Export Citation
  • Kim, H.-M., P. J. Webster, and J. A. Curry, 2011: Modulation of North Pacific tropical cyclone activity by three phases of ENSO. J. Climate, 24, 18391849.

    • Search Google Scholar
    • Export Citation
  • Kirchner, I., and H.-F. Graf, 1995: Volcanos and El Niño: Signal separation in Northern Hemisphere winter. Climate Dyn., 11, 341358.

    • Search Google Scholar
    • Export Citation
  • Kug, J.-S., F.-F. Jin, and S.-I. An, 2009: Two types of El Niño events: Cold tongue El Niño and warm pool El Niño. J. Climate, 22, 14991515.

    • Search Google Scholar
    • Export Citation
  • Larkin, N. K., and D. E. Harrison, 2005a: Global seasonal temperature and precipitation anomalies during El Niño autumn and winter. Geophys. Res. Lett., 32, L16705, doi:10.1029/2005GL022860.

    • Search Google Scholar
    • Export Citation
  • Larkin, N. K., and D. E. Harrison, 2005b: On the definition of El Niño and associated seasonal average U.S. weather anomalies. Geophys. Res. Lett., 32, L13705, doi:10.1029/2005GL022738.

    • Search Google Scholar
    • Export Citation
  • Lee, S.-K., C. Wang, and D. B. Enfield, 2010: On the impact of central Pacific warming events on Atlantic tropical storm activity. Geophys. Res. Lett., 37, L17702, doi:10.1029/2010GL044459.

    • Search Google Scholar
    • Export Citation
  • Liu, K. S., and J. C. L. Chan, 2003: Climatological characteristics and seasonal forecasting of tropical cyclones making landfall along the South China coast. Mon. Wea. Rev., 131, 16501662.

    • Search Google Scholar
    • Export Citation
  • Mann, H. B., and D. R. Whitney, 1947: On a test of whether one of two random variables is stochastically larger than the other. Ann. Math. Stat., 18, 5060.

    • Search Google Scholar
    • Export Citation
  • Matsuura, T., M. Yumoto, and S. Iizuka, 2003: A mechanism of interdecadal variability of tropical cyclone activity over the western North Pacific. Climate Dyn., 21, 105117.

    • Search Google Scholar
    • Export Citation
  • Nitta, T., and Z.-Z. Hu, 1996: Summer climate variability in China and its association with 500 hPa height and tropical convection. J. Meteor. Soc. Japan, 74, 425445.

    • Search Google Scholar
    • Export Citation
  • Rakhecha, P. R., and V. P. Singh, 2009: Tropical storms and hurricanes. Applied Hydrometeorology, P. Rakhecha, and V. P. Singh, Eds., Springer, 126162.

    • Search Google Scholar
    • Export Citation
  • Rayner, N. A., D. E. Parker, E. B. Horton, C. K. Folland, L. V. Alexander, D. P. Rowell, E. C. Kent, and A. Kaplan, 2003: Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. J. Geophys. Res., 108, 4407, doi:10.1029/2002JD002670.

    • Search Google Scholar
    • Export Citation
  • Sprent, P., and N. C. Smeeton, 2007: Applied Nonparametric Statistical Methods. 4th ed. Chapman and Hall, 530 pp.

  • Tu, J. Y., C. Chou, and P. S. Chu, 2009: The abrupt shift of typhoon activity in the vicinity of Taiwan and its association with western North Pacific–East Asian climate change. J. Climate, 22, 36173628.

    • Search Google Scholar
    • Export Citation
  • Wang, B., and J. C. L. Chan, 2002: How strong ENSO events affect tropical storm activity over the western North Pacific. J. Climate, 15, 16431658.

    • Search Google Scholar
    • Export Citation
  • Weng, H., K. Ashok, S. Behera, S. Rao, and T. Yamagata, 2007: Impacts of recent El Niño Modoki on dry/wet conditions in the Pacific rim during boreal summer. Climate Dyn., 29, 113129.

    • Search Google Scholar
    • Export Citation
  • Wilcoxon, F., 1945: Individual comparisons by ranking methods. Biom. Bull., 1, 8083.

  • Wu, L., B. Wang, and S. Geng, 2005: Growing typhoon influence on east Asia. Geophys. Res. Lett., 32, L18703, doi:10.1029/2005GL022937.

  • Wu, M., W. Chang, and W. Leung, 2004: Impacts of El Niño–Southern Oscillation events on tropical cyclone landfalling activity in the western North Pacific. J. Climate, 17, 14191428.

    • Search Google Scholar
    • Export Citation
  • Yeh, S.-W., J.-S. Kug, B. Dewitte, M.-H. Kwon, B. P. Kirtman, and F.-F. Jin, 2009: El Niño in a changing climate. Nature, 461, 511514.

    • Search Google Scholar
    • Export Citation
  • Yeh, S.-W., B. P. Kirtman, J.-S. Kug, W. Park, and M. Latif, 2011: Natural variability of the central Pacific El Niño event on multi-centennial timescales. Geophys. Res. Lett., 38, L02704, doi:10.1029/2010GL045886.

    • Search Google Scholar
    • Export Citation
  • Yumoto, M., and T. Matsuura, 2001: Interdecadal variability of tropical cyclone activity in the western North Pacific. J. Meteor. Soc. Japan, 79, 2335.

    • Search Google Scholar
    • Export Citation
  • Zar, J. H., 1972: Significance testing of the Spearman rank correlation coefficient. J. Amer. Stat. Assoc., 67, 578580.

  • View in gallery

    The four defined landfall subareas in East Asia: (i) Japan and Korea, (ii) China, (iii) Indochina and the Malay Peninsula, and (iv) the Philippines.

  • View in gallery

    TC track density (annual average TC frequency in each 2.5° × 2.5° grid box) during different ENSO regimes. The dashed gray curves denote the main paths of TC tracks.

  • View in gallery

    TC genesis density (contour: annual average frequency of TC formation in each 5° × 5° grid box) during different ENSO regimes. The contours with values less than 0.3 are omitted.

  • View in gallery

    Composite of SST anomalies (units: °C) during JJA of CP El Niño, EP El Niño, and La Niña years for the region (5°S–45°N, 90°E–120°W). The dashed rectangles indicate the regions of high positive SST anomalies in different ENSO regimes. The plotting area is outside of WNP to show the SST anomaly in the CP.

  • View in gallery

    Composite 600-hPa RH anomalies (%; shaded) and vertical wind shear anomalies (m s−1; contour) during JJA of CP El Niño, EP El Niño, and La Niña years. The rectangles indicate the regions favorable for TC formation in different ENSO regimes.

  • View in gallery

    Composite 500-hPa geopotential height and wind field anomalies during JJA of CP El Niño, EP El Niño, and La Niña years.

  • View in gallery

    Composite SST anomalies (units: °C) during SO of CP El Niño, EP El Niño, and La Niña years. The dashed rectangles indicate the regions of high SST anomalies in different ENSO regimes.

  • View in gallery

    Composite 600-hPa RH anomaly (%; shaded) and vertical wind shear magnitude anomalies (m s−1; contour) during SO of CP El Niño, EP El Niño, and La Niña years. The rectangles indicate the regions favorable for TC formation in different ENSO regimes.

  • View in gallery

    Composite 500-hPa geopotential height and wind field anomalies during SO of CP El Niño, EP El Niño, and La Niña years.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 303 284 37
PDF Downloads 241 229 28

Different El Niño Types and Tropical Cyclone Landfall in East Asia

View More View Less
  • 1 Department of Geography and Resource Management, The Chinese University of Hong Kong, Shatin, Hong Kong, China
  • | 2 Centre for Atmospheric Sciences, University of Cambridge, Cambridge, United Kingdom
  • | 3 Department of Geography and Resource Management, and Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Shatin, Hong Kong, China
  • | 4 Centre for Atmospheric Sciences, University of Cambridge, Cambridge, United Kingdom
© Get Permissions
Full access

Abstract

This study examines whether there exist significant differences in tropical cyclone (TC) landfall between central Pacific (CP) El Niño, eastern Pacific (EP) El Niño, and La Niña during the peak TC season (June–October) and how and to what extent CP El Niño influences TC landfall over East Asia for the period 1961–2009. The peak TC season is subdivided into summer [June–August (JJA)] and autumn [September–October (SO)]. The results are summarized as follows: (i) during the summer of CP El Niño years, TCs are more likely to make landfall over East Asia because of a strong easterly steering flow anomaly induced by the westward shift of the subtropical high and northward-shifted TC genesis. In particular, TCs have a greater probability of making landfall over Japan and Korea during the summer of CP El Niño years. (ii) In the autumn of CP El Niño years, TC landfall in most areas of East Asia, especially Indochina, the Malay Peninsula, and the Philippines, is likely to be suppressed because the large-scale circulation resembles that of EP El Niño years. (iii) During the whole peak TC season [June–October (JJASO)] of CP El Niño years, TCs are more likely to make landfall over Japan and Korea. TC landfall in East Asia as a whole has an insignificant association with CP El Niño during the peak TC season. In addition, more (less) TCs are likely to make landfall in China, Indochina, the Malay Peninsula, and the Philippines during the peak TC season of La Niña (EP El Niño) years.

Corresponding author address: Yee Leung, Department of Geography and Resource Management, Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Shatin, Hong Kong, China. E-mail: yeeleung@cuhk.edu.hk

Abstract

This study examines whether there exist significant differences in tropical cyclone (TC) landfall between central Pacific (CP) El Niño, eastern Pacific (EP) El Niño, and La Niña during the peak TC season (June–October) and how and to what extent CP El Niño influences TC landfall over East Asia for the period 1961–2009. The peak TC season is subdivided into summer [June–August (JJA)] and autumn [September–October (SO)]. The results are summarized as follows: (i) during the summer of CP El Niño years, TCs are more likely to make landfall over East Asia because of a strong easterly steering flow anomaly induced by the westward shift of the subtropical high and northward-shifted TC genesis. In particular, TCs have a greater probability of making landfall over Japan and Korea during the summer of CP El Niño years. (ii) In the autumn of CP El Niño years, TC landfall in most areas of East Asia, especially Indochina, the Malay Peninsula, and the Philippines, is likely to be suppressed because the large-scale circulation resembles that of EP El Niño years. (iii) During the whole peak TC season [June–October (JJASO)] of CP El Niño years, TCs are more likely to make landfall over Japan and Korea. TC landfall in East Asia as a whole has an insignificant association with CP El Niño during the peak TC season. In addition, more (less) TCs are likely to make landfall in China, Indochina, the Malay Peninsula, and the Philippines during the peak TC season of La Niña (EP El Niño) years.

Corresponding author address: Yee Leung, Department of Geography and Resource Management, Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Shatin, Hong Kong, China. E-mail: yeeleung@cuhk.edu.hk

1. Introduction

Tropical cyclones (TCs) induce most of their damages to coastal areas during or after landfall (Chan et al. 2004; Rakhecha and Singh 2009). The understanding of conditions leading to TC landfall is thus of economic, social, and scientific significance. TC landfall activity is largely influenced by genesis locations and steering flow (Goh and Chan 2010; Liu and Chan 2003; Wu et al. 2004). TC genesis is closely related to dynamic or thermodynamic factors such as sea surface temperature (SST), midtroposphere moisture (e.g., 600 hPa), and vertical wind shear (Camargo et al. 2007; Chia and Ropelewski 2002; Gray 1979). The steering flow is measured by midtroposphere wind fields, which are substantially influenced by the subtropical high (Chan 1984, 2005; Chan and Gray 1982; Harr and Elsberry 1991, 1995a,b; Holland 1993).

The El Niño–Southern Oscillation (ENSO) (Bjerknes 1969) is a powerful interplay between the tropical ocean and atmosphere in the Pacific basin. The modulation of TC activity by ENSO has been studied in terms of formation, landfall, and intensity (Camargo and Sobel 2005; Chan and Xu 2009; Chu 2004; Fudeyasu et al. 2006; Wang and Chan 2002; Wu et al. 2004). TC landfall in East Asia under the impact of El Niño and La Niña has been investigated in a number of studies. For example, Wang and Chan (2002) claimed that during El Niño summer and autumn the frequency of tropical storm formation increases remarkably in the southeastern western North Pacific (WNP) and decreases in the northwestern WNP. They further pointed out that TCs tend to recurve in strong El Niño years, but they track farther northward after being formed at higher latitudes during La Niña years because of the deepening of the west Pacific trough and retreat of the subtropical high. This implies that TCs tend to make landfall over East Asia more often during the autumn of a strong La Niña year than a strong El Niño year. During strong El Niño years, TCs have a better chance to interact with transient midlatitude synoptic systems, resulting in more recurved trajectories (Chu 2004). Wu et al. (2004) detected an enhanced number of landfalls in China, the Philippines, and the Malay Peninsula during autumn in La Niña years. However, Fudeyasu et al. (2006) argued that ENSO impacts TC activity not only during autumn but also during the summer monsoon season. Chan and Xu (2009) investigated the TC landfall activity from 1951 to 2006 in East Asia using wavelet analysis. Based on their study, TC landfall activities in East Asia have a significant period from 2 to 8 yr, which they linked to the influence of ENSO. Hence, previous research indicates that ENSO exerts a significant impact on TC landfall in East Asia and, in general, TCs tend to make landfall in East Asia, especially in China, the Philippines, and the Malay Peninsula, during the autumn of strong La Niña years.

During the past few years, a new type of Pacific warming was described in the central Pacific Ocean, referred to as El Niño Modoki (Ashok et al. 2007; Weng et al. 2007), “Dateline El Niño” (Larkin and Harrison 2005a,b), central Pacific (CP) El Niño, and “warm pool El Niño” (Kug et al. 2009). Yeh et al. (2009) argued that CP El Niño occurrences are related to changes in the background state under anthropogenic global warming, especially changes in the thermocline structure in the equatorial Pacific. The mechanisms causing CP El Niño, eastern Pacific (EP) El Niño, and La Niña to modulate TC variability have been investigated. Kim et al. (2009) found that CP El Niño tends to cause more TC landfalls across the Caribbean, the Gulf of Mexico, and the East Coast. The accumulated cyclone energy (ACE) shows that the overall cyclone activity is larger in CP El Niño than in EP El Niño in their study. However, based on an independent data analysis of Atlantic TC and further numerical modeling experiments, Lee et al. (2010) argued that it was premature to associate CP El Niño events with an increasing frequency of TC activity in the Gulf of Mexico and Caribbean Sea. Chen and Tam (2010) stated that TC frequency in the WNP basin is significantly positively correlated with the El Niño Modoki index (EMI) (Ashok et al. 2007) during the peak TC season. On the contrary, the association between TC frequency and the Niño-3 index is insignificant because of the mutual cancellation between enhanced and reduced TC frequency in the different ENSO domains. Kim et al. (2011) further examined the modulation by CP El Niño, EP El Niño, and La Niña of TC activity in the whole Pacific and compared the results with those derived only for the WNP in Chen and Tam (2010). They claimed that the positive TC formation anomaly in CP El Niño shifts to the west in a pattern very different from EP El Niño. There is further discussion that the TC formation over the northwestern part of the WNP increases the probability of TC propagation into the northern part of East Asia. CP El Niño is associated with an increase in the track density that represents the number of TC occurrences in the defined grid-based area over the central–western Pacific and a reduction over the eastern Pacific.

To recapitulate, our current understanding of the influence of CP El Niño on TC activity is that CP El Niño may enhance TC activity in the Caribbean, the Gulf of Mexico, and the East Coast and inhibit TC activity in the central and western Pacific. However, because of the high inherent variability it obviously needs longer time series to support these findings. Additionally, more TCs are expected to form over the northwestern part of the WNP and their likelihood of occurrence in East Asia to increase during CP El Niño years. However, little attention has been paid to TC landfall in East Asia corresponding to different El Niño types. The objective of this study is to examine whether there exist significant differences in TC landfall between CP El Niño, EP El Niño, and La Niña during the peak TC season (June–October) and how and to what extent CP El Niño influences TC landfall over East Asia. With an increasing number of CP El Niño events (Yeh et al. 2011, 2009), based on observed data and simulations, advancements in the understanding of TC landfall characteristics associated with CP El Niño, EP El Niño, and La Niña are important for disaster preparation and mitigation.

This paper is organized as follows: section 2 presents the data and methodology. Section 3 discusses the results. Section 4 describes the large-scale environments in different ENSO regimes. The conclusions are given in section 5.

2. Data and methodology

The TC best-track dataset is made available from the Japan Meteorological Agency (JMA) Regional Specialized Meteorological Centre Tokyo (RSMC Tokyo) (available online at http://www.jma.go.jp/jma/jma-eng/jma-center/rsmc-hp-pub-eg/besttrack.html). The original TC best-track dataset is processed on the Environmental Systems Research Institute (ESRI) ArcGIS 9.3 desktop to generate shape files of TC points and tracks. “Landfalling TC” in this study refers to any TC in WNP with its center crossing the coastline (Chan and Xu 2009). The time period for TCs is from 1961 to 2009. TCs are probably underestimated previous to the 1960s, when satellite observations became available for monitoring TCs (Chan 1985; see also Wu et al. 2004). It is noted that only TCs with the intensity of a tropical storm (maximum sustained wind >17 m s−1) or higher are considered because of the possibly large errors in counting the number of tropical depressions. Since most of TCs form in the peak TC season from June to October (JJASO) (Chen and Tam 2010), we collected TCs with intensity levels of tropical storm or higher during the peak season in WNP. JJASO are selected as the studying months. We have compared the results based in June–November (JJASON) with those based in JJASO and an insignificant difference is found between the two schemes. The monthly 1° × 1° SST dataset is obtained from the Hadley Centre (Rayner et al. 2003). Monthly means of meteorological variables (e.g., geopotential height and zonal and meridional wind fields) are obtained from the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis with a horizontal resolution of 2.5° × 2.5° and available from 1948 to 2007 (Kalnay et al. 1996).

The major concern in this study is to analyze the influence of different regimes of ENSO on TC landfall in East Asia. Therefore, the study area consists of East Asia and WNP (shown in Fig. 1). To differentiate the characteristics of TC landfall in different areas in East Asia, four subareas are defined in Fig. 1, described as follows: Japan and Korea, China, Indochina and the Malay Peninsula, and the Philippines. The landfall frequencies are calculated in these four subareas in particular, as well as in East Asia as a whole. Although the Philippines are geographically not part of East Asia we still define them as one of its subareas in line with previous studies (Wu et al. 2004; Chan and Xu 2009). It should be noted that the number of TC landfalls in East Asia as a whole for a particular year is not necessarily the sum of the numbers of TC landfalls in the four subareas. A TC that makes landfall in China (one landfall count in the “China” group), then recurves and makes landfall again in Japan or Korea (one landfall count in the “Japan and Korea” group), is counted only once in the “East Asia” group. The area for composite analysis is defined as a rectangular region from 90°E to 160°W in longitude and from 5°S to 45°N in latitude except for the plots of the composite SST anomaly (SSTA) in which the longitude extends to 120°W to indicate the general profiles of CP El Niño, EP El Niño, and La Niña.

Fig. 1.
Fig. 1.

The four defined landfall subareas in East Asia: (i) Japan and Korea, (ii) China, (iii) Indochina and the Malay Peninsula, and (iv) the Philippines.

Citation: Journal of Climate 25, 19; 10.1175/JCLI-D-11-00488.1

Different from the Niño-3.4 index, which may mix up EP warming and CP warming, the EMI and Niño-3 index can distinguish two types of Pacific warming events (Chen and Tam 2010). To compare the impacts of different Pacific warmings on TC landfall, the Niño-3 index, Niño-4 index, Niño-3.4 index, and EMI are employed to examine their associations with landfall in East Asia. The monthly Niño-3.4, Niño-3, and Niño-4 indexes are directly downloaded from the National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center (http://www.cpc.ncep.noaa.gov/data/indices/sstoi.indices). The EMI (Ashok et al. 2007) is used to measure the SST anomaly in the central Pacific. It is defined as
eq1
where [SSTA]A, [SSTA]B, and [SSTA]C indicate the SST anomaly averaged over the regions of (10°S–10°N, 165°E–140°W), (15°S–5°N, 110°–70°W), and (10°S–20°N, 125°–145°E), respectively. The JJASO months during which EMI and the Niño-3 index are larger than one standard deviation and the Niño-3 index is cooler than one standard deviation are designated as the CP El Niño, EP El Niño, and La Niña, respectively, after the linear trends are removed from these time series of indexes (Chen and Tam 2010; Kim et al. 2011, 2009). Subsequently, 8 yr with JJASO characterized by CP El Niño (1966, 1967, 1977, 1990, 1991, 1994, 2002, and 2004), 9 yr with JJASO characterized by EP El Niño (1963, 1965, 1969, 1972, 1976, 1982, 1983, 1987, and 1997) and 7 yr with JJASO characterized by La Niña (1964, 1970, 1973, 1975, 1988, 1999, and 2007) are defined accordingly. The CP El Niño events display decadal variability, which is different from the interannual variability of EP El Niño and La Niña events (Weng et al. 2007). TC behaviors have shown decadal/interdecadal variability in relation to atmospheric–oceanic fields, for example, SST, relative vorticity at 850 hPa, and outgoing longwave radiation in the North Pacific (Chan 2008; Matsuura et al. 2003; Yumoto and Matsuura 2001). In this study, our focus is on the frequency of landfalling TCs in East Asia corresponding to different ENSO phases. The decadal and interdecadal variability of TC landfalls over East Asia corresponding to different types of El Niños is to be examined in another study. It should be noted that 1963, 1982, 1983, and 1991 are years with strong volcanic eruptions. Previous research indicates that strong volcanic eruptions can influence ENSO according to radiative forcing (Adams et al. 2003; Kirchner and Graf 1995). We compared the research results based on two schemes: with and without the four years during which strong volcanic eruptions occurred. No significant difference is identified between the two schemes. Therefore, the four years with strong volcanic eruptions are employed for the following analyses.

The frequency of annual TC landfalls and ENSO indexes are ordinal and interval variables, respectively. The Spearman’s rank-order correlation analysis is used to measure the degree of monotonic relationship between two variables that are at least at ordinal scale (Altman 1991; Zar 1972). Like Pearson product–moment correlation, the Spearman’s rank-order correlation is also in a range between −1 and 1. A higher positive value of the coefficient indicates stronger positive association and vice versa. In this study, we used Spearman’s rank-order correlation analysis to unravel the linear associations between annual landfall frequency and ENSO indexes. A nonparametric Mann–Whitney U test (Mann and Whitney 1947; Sprent and Smeeton 2007; Wilcoxon 1945) is utilized to compare the longitude and latitude of TC genesis locations between CP El Niño, EP El Niño, and La Niña in section 4. This method has also been used to test differences in characteristics of grouped TCs (Chu 2002; Ho et al. 2009; Tu et al. 2009). The climate anomaly in this study is defined as the departure of a composite value of a variable (e.g., SST, relative humidity) during a particular period (e.g., CP El Niño summers) from the climatologically averaged value of that variable. Because of the small sample sizes of CP El Niño (eight events), EP El Niño (nine events), and La Niña (seven events) years in this study, the anomalies of selected variables are not tested for significance level.

3. Results

TC track density during CP El Niño, EP El Niño, and La Niña years is illustrated in Fig. 2 as in Wu et al. (2005). TC track density denotes the annual average TC frequency in each 2.5° × 2.5° grid box during different ENSO regimes. The dashed gray curves denote the main paths of TC tracks. The main path in Fig. 2 indicates a greater chance of making landfall over Japan and Korea during CP El Niño years than EP El Niño years. The main path in La Niña years displays a similar tendency to make landfall in Japan and Korea to that in CP El Niño years (Fig. 2). It should be noted that the number of TCs that made landfall in Japan and Korea are 92, 70, and 52 during eight CP El Niño, nine EP El Niño, and seven La Niña years, respectively. Figure 3 illustrates the density of TC genesis at which a TC attains the intensity level of a tropical storm for the first time during its lifespan in CP El Niño, EP El Niño, and La Niña years. The contours in Fig. 3 depict the annual average frequency of TC formation in each 5° × 5° grid box during different ENSO regimes. Figure 3 indicates that TC genesis locations in CP El Niño and EP El Niño years shift more eastward than those in La Niña years.

Fig. 2.
Fig. 2.

TC track density (annual average TC frequency in each 2.5° × 2.5° grid box) during different ENSO regimes. The dashed gray curves denote the main paths of TC tracks.

Citation: Journal of Climate 25, 19; 10.1175/JCLI-D-11-00488.1

Fig. 3.
Fig. 3.

TC genesis density (contour: annual average frequency of TC formation in each 5° × 5° grid box) during different ENSO regimes. The contours with values less than 0.3 are omitted.

Citation: Journal of Climate 25, 19; 10.1175/JCLI-D-11-00488.1

The results of Spearman’s rank-order correlation analysis between landfall frequency in the defined landfalling regions and different ENSO indexes from 1961 to 2009 are shown in Table 1. To substantiate Table 1, Table 2 illustrates the annual average number of TCs that made landfall in the defined regions during summer (JJA), autumn (SO), and the whole peak TC season (JJASO) of the defined CP El Niño, EP El Niño, and La Niña years. The annual average number of landfalling TCs in Table 2 is in good agreement with the results in Table 1. The boldface numbers in Table 2 indicate the annual average frequencies of landfalling TCs corresponding to significant correlation coefficients in Table 1. For example, corresponding to a significantly positive correlation between the frequency of TC landfall in Japan and Korea during JJASO and EMI, the annual average number of TC landfalls in these areas during JJASO of CP El Niño years is 6.9, which is larger than 5 and 5.1 in EP El Niño and La Niña years, respectively. The results indicate that the associations between landfall activities, EMI, the Niño-3.4 index, and the Niño-3 index are remarkably distinct during different seasons and in different landfall regions.

Table 1.

Correlations between annual landfall frequency and El Niño indexes from 1961 to 2009. East Asia JJASO represents the average number of TC landfalls in East Asia during JJASO. The other rows are likewise defined except Malay Peninsula JJASO, Malay Peninsula JJA, and Malay Peninsula SO, which represent the average number of TC landfalls in Indochina and the Malay Peninsula during JJASO, JJA, and SO, respectively.

Table 1.
Table 2.

The annual average frequency of TC landfall in different landfalling areas during summer, autumn, and the whole peak TC season of CP El Niño, EP El Niño, and La Niña years. The row names are defined as in Table 1. The boldface numbers indicate the annual average frequencies of landfalling TCs corresponding to significant correlation coefficients in Table 1.

Table 2.

During the peak TC season (JJASO), Table 1 indicates that TC landfall frequency in Japan and Korea has a significant association with EMI. This positive association during the peak TC season is largely attributed to the positive correlation between EMI and the frequency of landfall in Japan and Korea during summer (JJA). The Niño-3 index is found to have a significantly negative relationship with landfall frequency only in the Philippines and China during JJASO. No significant relationship is detected between landfall in East Asia as a whole and the Niño-3, Niño-4, and Niño-3.4 indexes (Table 1).

During summer (JJA), EMI is significantly positively correlated to landfall frequency in East Asia as a whole and in Japan and Korea. Therefore, more TCs are expected to make landfall over East Asia during the summer of CP El Niño years. Japan and Korea is the only subarea detected that has a significantly positive association with EMI during summer.

During autumn (SO), a negative correlation exists between EMI and landfall frequency in Indochina and the Malay Peninsula, and the Philippines. It seems that landfall frequencies in other areas have little relationship with EMI. The Niño-3 index is found to have a significantly negative relationship with landfall frequency in the Philippines, Indochina and the Malay Peninsula, and China during SO. It implies that TC landfall in the Philippines, Indochina and the Malay Peninsula, and China is modulated by EP El Niño and La Niña only during the autumn. There exist significantly negative correlations between landfall frequency in China, Indochina and the Malay Peninsula, and the Philippines and the Niño-3, Niño-4, and Niño-3.4 indexes. No significant correlation is detected between landfall frequency in Japan and Korea and the Niño-3, Niño-4, and Niño-3.4 indexes during autumn.

Therefore, EMI and other ENSO indexes have a clearly different relationship with TC landfall in East Asia in both the peak TC season and summer. In CP El Niño years, TCs tend to make landfall over Japan and Korea during the peak TC season, especially during summer. This result can explain Kim et al.’s (2011) study in which they found a higher TC track density near the Japanese and Korean coasts during JJASO of CP El Niño years. During summers of CP El Niño, more TCs tend to make landfall in East Asia. This is particularly interesting for Japan and Korea since this is the East Asian subregion with the highest correlation between the frequency of landfall and EMI. Significant distinctions between TC landfall frequencies in Japan and Korea during the summer of La Niña and El Niño years are not detected in Wu et al. (2004). This is likely due to differences in frequencies of landfalling TCs in Japan and Korea during CP El Niño and EP El Niño years that were not distinguished by Wu et al. (2004). During the autumn of La Niña years, TCs tend to make landfall over China, Indochina, the Malay Peninsula, and the Philippines since the Niño-3.4 and Niño-4 indexes are significantly negatively correlated with landfall frequencies in these areas (Table 1). This is again in good agreement with Wu et al. (2004).

4. Large-scale environments

a. TC genesis during summer

TC genesis location is defined to be the point at which a TC attains the intensity of a tropical storm for the first time during its lifespan. TCs that make landfall over Japan and Korea are likely to form in higher latitudes of their genesis compared with TCs making landfall in other areas of East Asia.

As shown in Table 3, TCs in CP El Niño form at a significantly higher average latitude than in EP El Niño. It is noteworthy that the average latitude of TC genesis locations in CP El Niño is significantly lower than in La Niña. No significant difference is detected in longitude between CP El Niño, EP El Niño, and La Niña. The poleward-shifted genesis location in CP El Niño plays an essential role in promoting the occurrence of TC landfalls in Korea and Japan during the summer of CP El Niño years.

Table 3.

The Mann–Whitney U test results between TC genesis locations during JJA of CP El Niño, EP El Niño, and La Niña years. (CP El Niño − EP El Niño)Latitude indicates the value when subtracting the average latitude of TC genesis locations in EP El Niño from that in CP El Niño. The other rows are defined likewise. The boldface numbers indicate that the difference in latitude or longitude is significant at the 0.01 or 0.05 significance level.

Table 3.

To analyze the processes underlying the shifts of TC genesis locations, the composite SST anomalies during the summer of CP El Niño, EP El Niño, and La Niña years are illustrated in Fig. 4. TC genesis locations are generally confined to the south of 30°N. The regions potentially favorable for TC genesis are thus required to fulfill this condition in the ensuing analysis. A higher SST induces stronger convection and midtroposphere relative humidity, which enhance the possibility of TC formation. Therefore, based on SST anomalies as shown in Fig. 4 where dashed rectangles indicate the regions of high positive SST anomaly in different ENSO regimes, the areas favorable for TC formation in CP El Niño are located more northwestward than those in EP El Niño years, but more equatorward than those in La Niña years. The composite midtroposphere relative humidity and vertical wind shear anomaly are shown in Fig. 5. Vertical wind shear is defined to be the difference of zonal wind between the 200- and 850-hPa levels. Dashed rectangles in Fig. 5 denote the areas favorable for TC formation with a positive relative humidity anomaly and weak vertical wind shear anomaly. The regions with a high SST anomaly (dashed rectangles in Fig. 4) in different ENSO regimes are in good agreement with regions favorable for TC formation (Fig. 5). It should be noted that during La Niña years, the areas favorable for TC formation (Fig. 5) include the region with a positive SST anomaly (Fig. 4), as well as the region around the Philippines. In CP El Niño, the areas promoting TC genesis clearly shift more northward than during EP El Niño, in which TCs tend to form in the southeastern part of WNP (Fig. 5). TCs in La Niña years are likely to form and develop in a region located northwest of those in CP and EP El Niño years where strong relative humidity and weak vertical wind shear prevail (dashed rectangles as shown in Fig. 5).

Fig. 4.
Fig. 4.

Composite of SST anomalies (units: °C) during JJA of CP El Niño, EP El Niño, and La Niña years for the region (5°S–45°N, 90°E–120°W). The dashed rectangles indicate the regions of high positive SST anomalies in different ENSO regimes. The plotting area is outside of WNP to show the SST anomaly in the CP.

Citation: Journal of Climate 25, 19; 10.1175/JCLI-D-11-00488.1

Fig. 5.
Fig. 5.

Composite 600-hPa RH anomalies (%; shaded) and vertical wind shear anomalies (m s−1; contour) during JJA of CP El Niño, EP El Niño, and La Niña years. The rectangles indicate the regions favorable for TC formation in different ENSO regimes.

Citation: Journal of Climate 25, 19; 10.1175/JCLI-D-11-00488.1

b. Steering flow during summer

TC tracks are largely controlled by the midtroposphere (e.g., 500 hPa) steering flow that is defined by large-scale circulation (e.g., monsoon systems, the subtropical high, and the midlatitude westerlies). The composite 500-hPa wind anomaly and geopotential height in CP El Niño, EP La Niña, and La Niña are shown in Fig. 6. The 5880-gpm contour represents the center of the subtropical high (Nitta and Hu 1996; Tu et al. 2009). The subtropical high center in CP El Niño covers a larger area, has a stronger intensity, and extends farther westward in comparison to EP El Niño. It implies that TCs are steered by strong and sustained easterlies much closer to the East Asian coast during CP El Niño. Furthermore, a remarkable easterly anomaly is observed near most of the East Asian coast in CP El Niño. It is also noted that a northeastward wind anomaly is found near the Korean coast and the northeastern Japanese coast during CP El Niño. The wind anomalies near the Korean and Japanese coasts, as a whole, promote TCs to make landfall over Japan and Korea although southwestward (landfall reducing) wind anomalies can be found near the southwestern Japanese coast. This, in addition to poleward-shifted genesis locations as shown in Table 3, is a combining factor that leads to more landfalls over the Japanese and Korean coasts in CP El Niño years.

Fig. 6.
Fig. 6.

Composite 500-hPa geopotential height and wind field anomalies during JJA of CP El Niño, EP El Niño, and La Niña years.

Citation: Journal of Climate 25, 19; 10.1175/JCLI-D-11-00488.1

In EP El Niño years, on the other hand, a strong westerly anomaly prevails in areas close to the East Asian coast and the subtropical high weakens and clearly retreats westward. The characteristics of large-scale circulation in EP El Niño are prone to cause TC recurvature over the ocean and to inhibit TC landfall in East Asia (Wang and Chan 2002).

In La Niña years, the subtropical high shifts westward and strong easterly wind anomalies prevail near the East Asian coast. Because the TCs form more westward, the TCs may be steered by strong easterlies to make landfall over China, Indochina, the Malay Peninsula, and the Philippines and have, hence, little chance to make landfall over Korea and Japan.

c. TC genesis during autumn

Figure 7 represents the SST anomaly during autumns of different ENSO regimes. Figure 8 indicates the composite 600-hPa relative humidity anomaly and the vertical wind shear anomaly during SO of CP El Niño, EP El Niño, and La Niña years. It is noted that the dashed rectangles in Fig. 8 indicate the regions favorable for TC formation in different ENSO regimes. The areas with positive anomalies of relative humidity and weak vertical wind shear are largely consistent with the areas with positive SST anomalies. The areas favorable for TC formation in CP El Niño are slightly shifted northward compared to those in EP El Niño (dashed rectangles shown in Fig. 8). In other words, the difference between the variables influencing TC genesis in two El Niño regimes is weaker but the difference between mean latitudes of genesis locations is still measurably significant according to the Mann–Whitney U test (Table 4).

Fig. 7.
Fig. 7.

Composite SST anomalies (units: °C) during SO of CP El Niño, EP El Niño, and La Niña years. The dashed rectangles indicate the regions of high SST anomalies in different ENSO regimes.

Citation: Journal of Climate 25, 19; 10.1175/JCLI-D-11-00488.1

Fig. 8.
Fig. 8.

Composite 600-hPa RH anomaly (%; shaded) and vertical wind shear magnitude anomalies (m s−1; contour) during SO of CP El Niño, EP El Niño, and La Niña years. The rectangles indicate the regions favorable for TC formation in different ENSO regimes.

Citation: Journal of Climate 25, 19; 10.1175/JCLI-D-11-00488.1

Table 4.

The Mann–Whitney U test results between TC genesis locations during SO of CP El Niño, EP El Niño, and La Niña years. The row names are defined as in Table 3. The boldface numbers indicate that the difference in latitude or longitude is significant at the 0.01 or 0.05 significance level.

Table 4.

However, in SO of La Niña years, areas favorable for TC genesis shift to the west of 155°E (see Fig. 8). In contrast, areas favorable for TC genesis in CP El Niño and EP El Niño are in general located to the east of 155°E (refer to Fig. 8). Because of the westward shifting of TC genesis locations during the autumn of La Niña years, TCs tend to make landfall over East Asia. However, TCs have less chance of making landfall over East Asia during the autumn of CP El Niño and EP El Niño years. In contrast to CP El Niño summer (Fig. 5), the area with positive anomalies of relative humidity and weak vertical wind shear in CP El Niño autumn shifts more southeastward (Fig. 8).

d. Steering flow during autumn

The modulation of CP El Niño on TC landfall in East Asia during autumn (September and October) is not significant except that a negative association with EMI is detected for Indochina and the Malay Peninsula. However, TC landfall in East Asia has a significantly negative correlation with the Niño-3 index during autumn. This relationship indicates that TCs are likely to make landfall over East Asia during the autumn of La Niña years except in Japan and Korea. This result is consistent with Wu et al. (2004) and Kim et al. (2011). The composite 500-hPa wind field anomaly and geopotential height field illustrate that westerly anomalies prevail in the autumn of CP El Niño years (Fig. 9). The composite 200- and 850-hPa wind anomalies show similar characteristics to the wind anomalies for the three ENSO regimes with the 500-hPa layer (figure not shown). The wind field anomaly is, however, weaker than that during EP El Niño. The western edge of the subtropical high center is nearly at the same position during the autumn of EP El Niño and CP El Niño years (Fig. 9). The center of the subtropical high (depicted by the 5880-gpm contour) in CP El Niño covers a slightly larger area and is more intense than that during EP El Niño. This leads to an easterly wind anomaly centered at around 35°N and 140°E for CP El Niño, favoring TC landfall over the northern part of East Asia compared to EP El Niño. Therefore, both the composite wind field and geopotential height anomalies suggest fewer landfalls over East Asia during the autumn of both CP El Niño and EP El Niño years as compared with La Niña years.

Fig. 9.
Fig. 9.

Composite 500-hPa geopotential height and wind field anomalies during SO of CP El Niño, EP El Niño, and La Niña years.

Citation: Journal of Climate 25, 19; 10.1175/JCLI-D-11-00488.1

The strong easterly anomaly near the East Asian coast during La Niña plays an important role in steering the TCs to make landfall over East Asia. It should be noted that an easterly wind anomaly appears near the southern Japanese coast, while a northerly wind anomaly occurs close to the Korean coast. This characteristic of the large-scale circulation during the autumn of La Niña years may suppress TC landfall over Japan and Korea.

5. Conclusions

Previous research on impacts of CP El Niño, EP El Niño, and La Niña on TC activity has shown significant influences in terms of TC formation and tracks. In the present study, we focus on how and to what extent CP El Niño influences characteristics of TC landfall over East Asia in comparison with EP El Niño and La Niña. Existing findings suggest that significant differences in landfall activity over East Asia exist merely during autumn in EP El Niño and La Niña years (Wang and Chan 2002; Wu et al. 2004). In summer, it seemed that no significant difference in TC landfall activity over East Asia existed between El Niño and La Niña.

In this study, the peak TC season (JJASO) is divided into two parts: summer (JJA) and autumn (SO). Significant associations are found between TC landfall characteristics over East Asia and summer and autumn of CP El Niño, EP El Niño, and La Niña years and are summarized as follows:

  1. During the summer of CP El Niño years, TCs are more likely to make landfall over East Asia because of a strong easterly steering flow anomaly induced by the westward shift of the subtropical high and northward-shifted TC genesis. In particular, TCs have a remarkable tendency to make landfall over Japan and Korea during the summer of CP El Niño years. The large-scale circulation during CP El Niño has much in common with that during La Niña based on composite wind anomalies. During summers of EP El Niño and La Niña years, no significant correlation is detected between the frequency of TC landfall in East Asia and the ENSO indexes.

  2. TC landfall in most areas of East Asia, especially Indochina, the Malay Peninsula, and the Philippines, is likely to be suppressed in the autumn of CP El Niño years because the large-scale circulation resembles that of EP El Niño. During the autumn of EP El Niño (La Niña) years, TC landfall activities seem to be suppressed (enhanced) in East Asia except for Japan and Korea because of strong westerly (easterly) anomalies and enhanced TC formation in southeastern (northwestern) WNP.

  3. During the whole peak TC season (JJASO) of CP El Niño years, TCs tend to make landfall over Japan and Korea. TC landfall in East Asia as a whole has an insignificant association with CP El Niño during the peak TC season. At the same time, more (less) TCs are likely to make landfall in China and the Philippines during the peak TC season of La Niña (EP El Niño) years.

As summarized in the introduction, although some studies have investigated the variability of TCs in genesis and tracks during CP El Niño (Chen and Tam 2010; Kim et al. 2011; Lee et al. 2010), little attention has been devoted to TC landfall in East Asia in connection to different El Niño types. This study is therefore the first attempt to discover the variability of landfalling TCs in East Asia during CP El Niño years. The differences in landfalling TCs during summers of CP and EP El Niño years are uncovered in the present study. In contrast to Wu et al. (2004), where differences in TCs making landfall over East Asia are detected only during autumn between El Niño and La Niña, we demonstrate that TCs have a remarkable tendency to make landfall over East Asia during the summer of CP El Niño years. This tendency is mainly attributed to more landfalls over Japan and Korea during the summer of CP El Niño years. We show that TCs are more likely to make landfall over Japan and Korea during peak seasons of CP El Niño years. In previous studies (Wang and Chan 2002; Wu et al. 2004) this was not detected because signals of CP and EP El Niños were not separated in their analyses.

The occurrence of CP El Niño tends to increase under the background of climate change (Yeh et al. 2009). In this study, CP El Niño leads to shifts in the seasonality and area of landfalling TCs in East Asia. This shift is more likely to affect people and properties along the Japanese and Korean coasts during the peak TC season, especially during summer. Despite an insufficient number of CP El Niño events in this study, the present results still urge the scientific communities to take into account CP El Niño for TC prediction under climate change.

Acknowledgments

This research was supported by the Geographical Modeling and Geocomputation Program under the Focused Investment Scheme of The Chinese University of Hong Kong. The authors thank the anonymous reviewers for valuable comments.

REFERENCES

  • Adams, J. B., M. E. Mann, and C. M. Ammann, 2003: Proxy evidence for an El Niño-like response to volcanic forcing. Nature, 426, 274278.

    • Search Google Scholar
    • Export Citation
  • Altman, D. G., 1991: Practical Statistics for Medical Research. Chapman and Hall/CRC, 611 pp.

  • Ashok, K., S. K. Behera, S. A. Rao, H. Weng, and T. Yamagata, 2007: El Niño Modoki and its possible teleconnection. J. Geophys. Res., 112, C11007, doi:10.1029/2006JC003798.

    • Search Google Scholar
    • Export Citation
  • Bjerknes, J., 1969: Atmospheric teleconnections from the equatorial Pacific. Mon. Wea. Rev., 97, 163172.

  • Camargo, S. J., and A. H. Sobel, 2005: Western North Pacific tropical cyclone intensity and ENSO. J. Climate, 18, 29963006.

  • Camargo, S. J., A. H. Sobel, A. G. Barnston, and K. A. Emanuel, 2007: Tropical cyclone genesis potential index in climate models. Tellus, 59A, 428443.

    • Search Google Scholar
    • Export Citation
  • Chan, J. C. L., 1984: An observational study of the physical processes responsible for tropical cyclone motion. J. Atmos. Sci., 41, 10361048.

    • Search Google Scholar
    • Export Citation
  • Chan, J. C. L., 1985: Tropical cyclone activity in the northwest Pacific in relation to the El Niño/Southern Oscillation phenomena. Mon. Wea. Rev., 113, 599606.

    • Search Google Scholar
    • Export Citation
  • Chan, J. C. L., 2005: The physics of tropical cyclone motion. Annu. Rev. Fluid Mech., 37, 99128.

  • Chan, J. C. L., 2008: Decadal variations of intense typhoon occurrence in the western North Pacific. Proc. Roy. Soc., Math. Phys. Eng. Sci., 464, 249272.

    • Search Google Scholar
    • Export Citation
  • Chan, J. C. L., and W. M. Gray, 1982: Tropical cyclone movement and surrounding flow relationships. Mon. Wea. Rev., 110, 13541374.

  • Chan, J. C. L., and M. Xu, 2009: Inter-annual and inter-decadal variations of landfalling tropical cyclones in East Asia. Part I: Time series analysis. Int. J. Climatol., 29, 12851293.

    • Search Google Scholar
    • Export Citation
  • Chan, J. C. L., K. Liu, S. E. Ching, and E. S. T. Lai, 2004: Asymmetric distribution of convection associated with tropical cyclones making landfall along the South China coast. Mon. Wea. Rev., 132, 24102420.

    • Search Google Scholar
    • Export Citation
  • Chen, G., and C.-Y. Tam, 2010: Different impacts of two kinds of Pacific Ocean warming on tropical cyclone frequency over the western North Pacific. Geophys. Res. Lett., 37, L01803, doi:10.1029/2009GL041708.

    • Search Google Scholar
    • Export Citation
  • Chia, H. H., and C. Ropelewski, 2002: The interannual variability in the genesis location of tropical cyclones in the northwest Pacific. J. Climate, 15, 29342944.

    • Search Google Scholar
    • Export Citation
  • Chu, P.-S., 2002: Large-scale circulation features associated with decadal variations of tropical cyclone activity over the central North Pacific. J. Climate, 15, 26782689.

    • Search Google Scholar
    • Export Citation
  • Chu, P.-S., 2004: ENSO and tropical cyclone activity. Hurricanes and Typhoons: Past, Present, and Potential, R. J. Murnane and K.-B. Liu, Eds., Columbia Press, 297–332.

  • Fudeyasu, H., S. Iizuka, and T. Matsuura, 2006: Impact of ENSO on landfall characteristics of tropical cyclones over the western North Pacific during the summer monsoon season. Geophys. Res. Lett., 33, L21815, doi:10.1029/2006GL027449.

    • Search Google Scholar
    • Export Citation
  • Goh, Z.-C. A., and J. C. L. Chan, 2010: An improved statistical scheme for the prediction of tropical cyclones making landfall in South China. Wea. Forecasting, 25, 587593.

    • Search Google Scholar
    • Export Citation
  • Gray, W. M., 1979: Hurricanes: Their formation, structure and likely role in the tropical circulation. Meteorology over the Tropical Oceans, D. B. Shaw, Ed., Roy. Meteor. Soc., 155–218.

  • Harr, P. A., and R. L. Elsberry, 1991: Tropical cyclone track characteristics as a function of large-scale circulation anomalies. Mon. Wea. Rev., 119, 14481468.

    • Search Google Scholar
    • Export Citation
  • Harr, P. A., and R. L. Elsberry, 1995a: Large-scale circulation variability over the tropical western North Pacific. Part I: Spatial patterns and tropical cyclone characteristics. Mon. Wea. Rev., 123, 12251246.

    • Search Google Scholar
    • Export Citation
  • Harr, P. A., and R. L. Elsberry, 1995b: Large-scale circulation variability over the tropical western North Pacific. Part II: Persistence and transition characteristics. Mon. Wea. Rev., 123, 12471268.

    • Search Google Scholar
    • Export Citation
  • Ho, C.-H., H.-S. Kim, J.-H. Jeong, and S.-W. Son, 2009: Influence of stratospheric quasi-biennial oscillation on tropical cyclone tracks in the western North Pacific. Geophys. Res. Lett., 36, L06702, doi:10.1029/2009GL037163.

    • Search Google Scholar
    • Export Citation
  • Holland, G. J., 1993: Tropical cyclone motion. Global Guide to Tropical Cyclone Forecasting, G. Holland, Ed., WMO, 3.1–3.46.

  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77, 437471.

  • Kim, H.-M., P. J. Webster, and J. A. Curry, 2009: Impact of shifting patterns of Pacific Ocean warming on North Atlantic tropical cyclones. Science, 325, 77 80.

    • Search Google Scholar
    • Export Citation
  • Kim, H.-M., P. J. Webster, and J. A. Curry, 2011: Modulation of North Pacific tropical cyclone activity by three phases of ENSO. J. Climate, 24, 18391849.

    • Search Google Scholar
    • Export Citation
  • Kirchner, I., and H.-F. Graf, 1995: Volcanos and El Niño: Signal separation in Northern Hemisphere winter. Climate Dyn., 11, 341358.

    • Search Google Scholar
    • Export Citation
  • Kug, J.-S., F.-F. Jin, and S.-I. An, 2009: Two types of El Niño events: Cold tongue El Niño and warm pool El Niño. J. Climate, 22, 14991515.

    • Search Google Scholar
    • Export Citation
  • Larkin, N. K., and D. E. Harrison, 2005a: Global seasonal temperature and precipitation anomalies during El Niño autumn and winter. Geophys. Res. Lett., 32, L16705, doi:10.1029/2005GL022860.

    • Search Google Scholar
    • Export Citation
  • Larkin, N. K., and D. E. Harrison, 2005b: On the definition of El Niño and associated seasonal average U.S. weather anomalies. Geophys. Res. Lett., 32, L13705, doi:10.1029/2005GL022738.

    • Search Google Scholar
    • Export Citation
  • Lee, S.-K., C. Wang, and D. B. Enfield, 2010: On the impact of central Pacific warming events on Atlantic tropical storm activity. Geophys. Res. Lett., 37, L17702, doi:10.1029/2010GL044459.

    • Search Google Scholar
    • Export Citation
  • Liu, K. S., and J. C. L. Chan, 2003: Climatological characteristics and seasonal forecasting of tropical cyclones making landfall along the South China coast. Mon. Wea. Rev., 131, 16501662.

    • Search Google Scholar
    • Export Citation
  • Mann, H. B., and D. R. Whitney, 1947: On a test of whether one of two random variables is stochastically larger than the other. Ann. Math. Stat., 18, 5060.

    • Search Google Scholar
    • Export Citation
  • Matsuura, T., M. Yumoto, and S. Iizuka, 2003: A mechanism of interdecadal variability of tropical cyclone activity over the western North Pacific. Climate Dyn., 21, 105117.

    • Search Google Scholar
    • Export Citation
  • Nitta, T., and Z.-Z. Hu, 1996: Summer climate variability in China and its association with 500 hPa height and tropical convection. J. Meteor. Soc. Japan, 74, 425445.

    • Search Google Scholar
    • Export Citation
  • Rakhecha, P. R., and V. P. Singh, 2009: Tropical storms and hurricanes. Applied Hydrometeorology, P. Rakhecha, and V. P. Singh, Eds., Springer, 126162.

    • Search Google Scholar
    • Export Citation
  • Rayner, N. A., D. E. Parker, E. B. Horton, C. K. Folland, L. V. Alexander, D. P. Rowell, E. C. Kent, and A. Kaplan, 2003: Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. J. Geophys. Res., 108, 4407, doi:10.1029/2002JD002670.

    • Search Google Scholar
    • Export Citation
  • Sprent, P., and N. C. Smeeton, 2007: Applied Nonparametric Statistical Methods. 4th ed. Chapman and Hall, 530 pp.

  • Tu, J. Y., C. Chou, and P. S. Chu, 2009: The abrupt shift of typhoon activity in the vicinity of Taiwan and its association with western North Pacific–East Asian climate change. J. Climate, 22, 36173628.

    • Search Google Scholar
    • Export Citation
  • Wang, B., and J. C. L. Chan, 2002: How strong ENSO events affect tropical storm activity over the western North Pacific. J. Climate, 15, 16431658.

    • Search Google Scholar
    • Export Citation
  • Weng, H., K. Ashok, S. Behera, S. Rao, and T. Yamagata, 2007: Impacts of recent El Niño Modoki on dry/wet conditions in the Pacific rim during boreal summer. Climate Dyn., 29, 113129.

    • Search Google Scholar
    • Export Citation
  • Wilcoxon, F., 1945: Individual comparisons by ranking methods. Biom. Bull., 1, 8083.

  • Wu, L., B. Wang, and S. Geng, 2005: Growing typhoon influence on east Asia. Geophys. Res. Lett., 32, L18703, doi:10.1029/2005GL022937.

  • Wu, M., W. Chang, and W. Leung, 2004: Impacts of El Niño–Southern Oscillation events on tropical cyclone landfalling activity in the western North Pacific. J. Climate, 17, 14191428.

    • Search Google Scholar
    • Export Citation
  • Yeh, S.-W., J.-S. Kug, B. Dewitte, M.-H. Kwon, B. P. Kirtman, and F.-F. Jin, 2009: El Niño in a changing climate. Nature, 461, 511514.

    • Search Google Scholar
    • Export Citation
  • Yeh, S.-W., B. P. Kirtman, J.-S. Kug, W. Park, and M. Latif, 2011: Natural variability of the central Pacific El Niño event on multi-centennial timescales. Geophys. Res. Lett., 38, L02704, doi:10.1029/2010GL045886.

    • Search Google Scholar
    • Export Citation
  • Yumoto, M., and T. Matsuura, 2001: Interdecadal variability of tropical cyclone activity in the western North Pacific. J. Meteor. Soc. Japan, 79, 2335.

    • Search Google Scholar
    • Export Citation
  • Zar, J. H., 1972: Significance testing of the Spearman rank correlation coefficient. J. Amer. Stat. Assoc., 67, 578580.

Save