本研究使用觀測資料及高解析度大氣模式(High-Resolution Atmospheric Model, HiRAM) 的模擬結果，探究Madden-Julian oscillation (MJO)對西北太平洋颱風活動的影響，尤其聚焦於颱風季(六至九月)時之南海盆地。觀測分析顯示，MJO顯著地影響位於南海盆地生成的颱風，較多(少)的颱風會在MJO處於增強(抑制)對流相位時形成。此外MJO也在控制南海盆地上西行與東行颱風路徑方面扮演了重要角色。HiRAM的模擬顯示，當大氣具有較快傳播速度之MJO時，模式將能適當地重現南海盆地上，和MJO變異有關之颱風活動整體特徵變化(包含其生成與路徑)。
於RCP8.5暖化情境下，HiRAM推估在21世紀末（2075-2099），MJO八相異相位的颱風生成數量皆會顯著地下降。此外，若與模擬現今氣候狀態（1980-2004年）之模式結果相比，藉由比較增強對流相位和抑制對流相位之間的颱風日平均生成率，HiRAM還預測出MJO對南海盆地生成的颱風影響將會更大，對於颱風移動軌跡也有較強的調節作用。

This study investigated the impacts of Madden-Julian Oscillation (MJO) on tropical cyclone (TC) activity over the western North Pacific (WNP), with a focus on the South China Sea (SCS), based on results from observations and high-resolution atmospheric model (HiRAM) simulations. Observational analyses showed that MJO imposes marked impacts on TC genesis over the SCS, with more (less) TC formations during the enhanced (suppressed) convection phases of MJO. Besides, MJO also plays an important role in modulating the tracks of both westward-moving and eastward-moving TCs in the SCS. Results from HiRAM simulations demonstrated that, while the model generates an MJO of faster propagation, the general features of TC activity (including genesis and track) changes over the SCS associated with MJO variability have been properly produced by HiRAM.
During the late 21th century period (2075-2099), TC genesis numbers in eight different MJO phases are expected to decrease significantly as projected by HiRAM under the RCP 8.5 warming scenario. Furthermore, HiRAM also projects a greater impact of MJO on TC genesis over the SCS, with a larger contrast of averaged daily genesis rate (DGR) between enhanced and suppressed convection phases as well as a greater modulation of MJO on TC moving trajectories compared to those in present climate state simulations (1980-2004).

Arnold, N. P., Branson, M., Kuang, Z., Randall, D. A. and Tziperman, E. (2015) MJO intensification with warming in the super-parameterized CESM. Journal of Climate, 28, 2706–2724. https://doi.org/10.1175/JCLI-D-14-00494.1.
Barrett, B. S. and Leslie, L. M. (2009) Links between tropical cyclone activity and Madden–Julian oscillation phase in the North Atlantic and northeast Pacific basins. Monthly Weather Review, 137, 727–744. https://doi.org/10.1175/2008MWR2602.1.
Bell, G. D., Halpert, M. S., Schnell, R. C., Higgins, R. W., Lawrimore, J., Kousky, V. E., Tinker, R., Thiaw, W., Chelliah, M. and Artusa, A. (2000) Climate assessment for 1999. Bulletin of the American Meteorological Society, 81, 1328-1328. https://doi.org/10.1175/1520-0477(2000)81[s1:CAF]2.0.CO;2.
Bender, M. A., Knutson, T. R., Tuleya, R. E., Sirutis, J. J., Vecchi, G. A., Garner, S. T. and Held, I. M. (2010) Modeled impact of anthropogenic warming on the frequency of intense Atlantic hurricanes. Science, 327, 454-458. https://doi.org/10.1126/science.1180568.
Bessafi, M. and Wheeler, M. C. (2006) Modulation of south Indian Ocean tropical cyclones by the Madden–Julian oscillation and convectively coupled equatorial waves. Monthly Weather Review, 134, 638–656. https://doi.org/10.1175/MWR3087.1.
Bui, H. X., and E. D. Maloney, 2018: Changes in Madden–Julian oscillation precipitation and wind variance under global warming. Geophysical Research Letters, 45, 7148–7155. https://doi.org/10.1029/2018GL078504.
Bretherton, C. S., McCaa, J. R. and Grenier, H. (2004) A new parameterization for shallow cumulus convection and its application to marine subtropical cloud-topped boundary layers. Part I: Description and 1D results. Monthly Weather Review, 132, 864–882. https://doi.org/10.1175/1520-0493(2004)132<0864:ANPFSC>2.0.CO;2.
Chan, J. C. L. (2000) Tropical cyclone activity over the western North Pacific associated with El Niño and La Niña events. Journal of Climate, 13, 2960–2972. https://doi.org/10.1175/1520-0442(2000)013<2960:TCAOTW>2.0.CO;2.
Chen, J.-H. and Lin, S.-J. (2011) The remarkable predictability of inter-annual variability of Atlantic hurricanes during the past decade. Geophysical Research Letters, 38, L11804. https://doi.org/10.1029/2011GL047629.
Cui, J. and Li, T. (2019) Changes of MJO propagation characteristics under global warming. Climate Dynamic, 53, 5311. https://doi.org/10.1007/s00382-019-04864-4.
Dee, D. P., Uppala, S. M., Simmons, A. J., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M. A., Balsamo, G., Bauer, P., Bechtold, P., Beljaars, A. C. M., van de Berg, L., Bidlot, J., Bormann, N., Delsol, C., Dragani, R., Fuentes, M., Geer, A. J., Haimberger, L., Healy, S. B., Hersbach, H., Hólm, E. V., Isaksen, L., Kållberg, P., Köhler, M., Matricardi, M., McNally, A. P., MongeSanz, B. M., Morcrette, J.-J., Park, B.-K., Peubey, C., de Rosnay, P., Tavolato, C., Thépaut, J.-N. and Vitart, F. (2011) The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Quarterly Journal Royal Meteorological Society, 137, 553-597. https://doi.org/10.1002/qj.828.
Emanuel, K. A. (2005) Increasing destructiveness of tropical cyclones over the past 30 years. Nature, 436, 686-688. https://doi.org/10.1038/nature03906.
Emanuel, K. A. (2010) Tropical cyclone activity downscaled from NOAA-CIRES reanalysis, 1908-1958. Journal of Advances in Modeling Earth Systems, 2. https://doi.org/10.3894/JAMES.2010.2.1.
Emanuel, K. A. and Nolan, D. S. (2004) Tropical cyclone activity and the global climate system. In the 26th Conference on Hurricanes and Tropical Meteorology. American Meteorological Society: Miami, FL.
Goh, A. Z. C. and Chan, J. C.-L. (2010) Interannual and interdecadal variations of tropical cyclone activity in the South China Sea. International Journal of Climatology, 30 (6), 827–843. https://doi.org/10.1002/joc.1943
Gray, W. M. (1979) Hurricanes: Their formation, structure and likely role in the tropical circulation. In Meteorology over Tropical Oceans, Shaw, D. B. (ed.). Royal Meteorological Society: James Glaisher House, Grenville Place, Bracknell, Berkshire, RG12 1BX; 155–218.
Hall, J. D., Matthews, A. J. and Karoly, D. J. (2001) The modulation of tropical cyclone activity in the Australian region by the Madden–Julian oscillation. Monthly Weather Review, 129, 2970–2982. https://doi.org/10.1175/1520-0493(2001)129<2970:TMOTCA>2.0.CO;2.
Jiang, X., Zhao, M. and Waliser, D. E. (2012) Modulation of tropical cyclones over the eastern Pacific by the intraseasonal variability simulated in an AGCM. Journal of Climate, 25, 6524–6538. https://doi.org/10.1175/JCLI-D-11-00531.1.
Kim, D., Lee, M. I., Kim, H. M., Schubert, S. D. and Yoo, J. H. (2014) The modulation of tropical storm activity in the Western North Pacific by the Madden Julian Oscillation in GEOS-5 AGCM experiments. Atmospheric Science Letters, 15, 335-341. https://doi.org/10.1002/asl2.509.
Kim, D., Sperber, K., Stern, W., Waliser, D., Kang, I. S., Maloney, E., Wang, W., Weickmann, K., Benedict, J., Khairoutdinov, M., Lee, M. I., Neale, R., Suarez, M., Thayer-Calder, K. and Zhang, G. (2009) Application of MJO simulation diagnostics to climate models. Journal of Climate, 22, 6413–6436. https://doi.org/10.1175/2009JCLI3063.1.
Kim, J.-H., Ho, C.-H., Kim, H.-S., Sui, C.-H. and Park, S. K. (2008) Systematic variation of summertime tropical cyclone activity in the western North Pacific in relation to the Madden–Julian oscillation. Journal of Climate, 21, 1171–1191. https://doi.org/10.1175/2007JCLI1493.1.
Knutson, T. R., Sirutis, J. J., Garner, S. T., Held, I. M. and Tuleya, R. E. (2007) Simulation of the recent multidecadal increase of Atlantic hurricane activity using an 18-kmgrid regional model. Bulletin of American Meteorological Society, 88, 1549-1565. https://doi.org/10.1175/BAMS-88-10-1549.
Knutson, T. R., Sirutis, J. J., Garner, S. T., Vecchi, G. A. and Held, I. M. (2008) Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions. Nature Geoscience, 1, 359-364. https://doi.org/10.1038/ngeo202.
Knutson, T. R., Sirutis, J. J., Vecchi, G. A., Garner, S., Zhao, M., Kim, H. S., Bender, M., Tuleya, R. E., Held, I. M. and Villarini, G. (2013) Dynamical downscaling projections of twenty-first-century Atlantic hurricane activity: CMIP3 and CMIP5 model-based scenarios. Journal of Climate, 26, 6591-6617. https://doi.org/10.1175/JCLI-D-1200539.1.
Korty, R. L., Camargo, S. J. and Galewsky, J. (2012) Tropical cyclone genesis factors in simulations of the last glacial maximum. Journal of Climate, 25, 4348-4365. https://doi.org/10.1175/JCLI-D-11-00517.1.
Li, R. C. Y. and Zhou, W. (2013a) Modulation of western North Pacific tropical cyclone activity by the ISO. Part I: Genesis and intensity. Journal of Climate, 26, 2904-2918. https://doi.org/10.1175/JCLI-D-12-00210.1.
Lin, S.-J. (2004) A “vertically Lagrangian” finite-volume dynamical core for global models. Monthly Weather Review, 132, 2293−2307. https://doi.org/10.1175/1520-0493(2004)132<2293:AVLFDC>2.0.CO;2.
Ling, Z., Wang, Y. and Wang, G. (2015) Impact of Intraseasonal Oscillations on the Activity of Tropical Cyclones in Summer over the South China Sea. Part I: Local Tropical Cyclones. Monthly Weather Review, 29, 855-868. https://doi.org/10.1175/JCLI-D-15-0617.1.
Madden, R. A. and Julian, P. R. (1971) Detection of a 40–50 day oscillation in the zonal wind in the tropical Pacific. Journal of the Atmospheric Sciences, 28 (5), 702–708. https://doi.org/10.1175/1520-0469(1971)028<0702:DOADOI>2.0.CO;2.
Madden, R. A. and Julian, P. R. (1972) Description of global-scale circulation cells in the Tropics with a 40–50 day period. Journal of the Atmospheric Sciences, 29 (6), 1109–1123. https://doi.org/10.1175/1520-0469(1972)029<1109: DOGSCC>2.0.CO;2.
Maloney, E. D. and Hartmann, D. L (2000a) Modulation of eastern North Pacific hurricanes by the Madden–Julian oscillation. Journal of Climate, 13, 1451–1460. https://doi.org/10.1175/1520-0442(2000)013<1451:MOENPH>2.0.CO;2.
Murakami, H. and Sugi, M. (2010) Effect of model resolution on tropical cyclone climate projections. The Scientific Online Letters on the Atmosphere, 6, 73-76, https://doi.org/10.2151/sola.2010-019.
Murakami, H. and Wang, B. (2010) Future change of North Atlantic tropical cyclone tracks: Projection by a 20-km-mesh global atmospheric model. Journal of Climate, 23, 2699-2712. https://doi.org/10.1007/s00382-011-1223-x.
Murakami, H., Wang, Y., Yoshimura, H., Mizuta, R., Sugi, M., Shindo, E., Adachi, Y., Yukimoto, S., Hosaka, M., Kusunoki, S., Ose, T. and Kitoh, A. (2012) Future changes in tropical cyclone activity projected by the new high resolution MRI-AGCM. Journal of Climate, 25, 3237-3260, https://doi.org/10.1175/JCLI-D-11-00415.1.
Murakami, H., Hsu, P. C., Arakawa, O. and Li, T. (2014) Influence of model biases on projected future changes in tropical cyclone frequency of occurrence. Journal of Climate, 27, 2159-2181, https://doi.org/10.1175/JCLI-D-13-00436.1.
Phan, V. T., Long, T. T., Hai, B. H. and Kieu, C. (2015) Seasonal forecasting of tropical cyclone activity in the coastal region of Vietnam using RegCM4.2. Climate Research, 62, 115-129. https://doi.org/10.3354/cr01267.
Rui, H. and Wang, B. (1990) Development characteristics and dynamic structure of tropical intraseasonal convection anomalies. Journal of the Atmospheric Sciences, 47, 357–379. https://doi.org/10.1175/1520-0469(1990)047<0357:DCADSO>2.0.CO;2.
Satoh, M., Oouchi, K., Nasuno, T., Taniguchi, H., Yamada, Y., Tomita, H., Kodama, C., Kinter, J., Achuthavarier, D., Managanello, J., Cash, B., Jung, T., Palmer, T. and Wedi, N. (2012) The intra-seasonal oscillation and its control of tropical cyclones simulated by high resolution global atmospheric models. Climate Dynamics, 39, 2185–2206. https://doi.org/10.1007/s00382-011-1235-6.
Subramanian, A., Jochum, M., Miller, A. J., Neale, R., Seo, H., Waliser, D. and Murtugudde, R. (2014). The MJO and global warming: A study in CCSM4. Climate Dynamics, 42 (7-8), 2019–2031. https://doi.org/10.1007/s00382-013-1846-1.
Tsou, C.-H., Huang, P.-Y., Tu, C.-Y., Chen, C.-T., Tzeng, T.-P. and Cheng, C.-T. (2016) Present simulation and future Typhoon activity projection over western North Pacific and Taiwan/East Coast of China in 20-km HiRAM climate model. Terrestrial Atmospheric Oceanic Sciences, 27(5), 687-703. https://doi.org/10.3319/TAO.2016.06.13.04.
Vitart F. (2009) Impact of the Madden Julian Oscillation on tropical storms and risk of landfall in the ECMWF forecast system. Geophysical Research Letters, 36, L15802. https://doi.org/10.1029/2009GL039089.
Wang, B. and Chan, J. C. L. (2002) How strong ENSO events affect tropical storm activity over the western North Pacific. Journal of Climate, 15, 1643–1658. https://doi.org/10.1175/1520-0442(2002)015<1643:HSEEAT>2.0.CO;2.
Wang, B. and Moon, J.-Y. (2017) Sub-seasonal prediction of extreme weather events. Bridging Science and Policy Implication for Managing Climate Extremes: Linking Science and Policy Implication, Chung, C.-S. and Wang, B., Eds., World Scientific, in press.
Wang, Z. and Fei, L. (1987) Manual for typhoon prediction. China Meteorology Press, Beijing, 260–287 (in Chinese).
Waple, A. M., Lawrimore, J. H., Halpert, M. S., Bell, G. D., Higgins, W., Lyon, B., Menne, M. J., Gleason, K. L., Schnell, R. C., Christy, J. R., Thiaw, W., Wright, W. J., Salinger, M. J., Alexander, L., Stone, R. S. and Camargo, S. J. (2002) Climate assessment for 2001. Bulletin of American Meteorological Society, 83, 938-938. https://doi.org/10.1175/1520-0477-83.6.S1.
Wheeler, M. C., and Hendon, H. H. (2004) An all-season real-time multivariate MJO index: Development of an index for monitoring and prediction. Monthly Weather Review, 132, 1917–1932. https://doi.org/10.1175/1520-0493(2004)132<1917:AARMMI>2.0.CO;2.
Yang, L., Du, Y., Wang, D., Wang, C. and Wang, X. (2015) Impact of intraseasonal oscillation on the tropical cyclone track in the South China Sea. Climate Dynamic, 44, 1505–1519. https://doi.org/10.1007/s00382-014-2180-y.
Ying, M., Knutson, T. R., Kamahori, H. and Lee, T. C. (2012) Impacts of climate change on tropical cyclones in the Western North Pacific Basin. Part II: Late twenty-first century projections. Tropical Cyclone Research and Review, 1, 231-241. https://doi.org/10.6057/2012TCRR02.09.
Yu, J.-Y., Chou, C. and Chiu, P.-G. (2009) A revised accumulated cyclone energy index. Geophysical Research Letters, 36, L14710. https://doi.org/10.1029/2009GL039254.
Yu, J.-Y. and Chiu, P.-G. (2012) Contrasting various metrics for measuring tropical cyclone activity. Terrestrial Atmospheric Oceanic Sciences, 23, 303-316. https://doi.org/10.3319/TAO.2011.11.23.01(A).
Zhang, C. (2005) Madden-Julian Oscillation. Reviews of Geophysics, 43, RG2003. https://doi.org/10.1029/2004RG000158.