The authors are grateful for reviewers’ comments, which resulted in an improved version of the manuscript. This study has been supported by the Climate Dynamics Program of the National Science Foundation under Grant ATM-94-00759 and the Marine Meteorology Program of Office of Naval Research. This is the School of Ocean and Earth Science and Technology Publication No. 4192.
Chen, L.-X., and Z. Jin, 1984: The medium-range variations of the summer monsoon circulation system over east Asia. Adv. Atmos. Sci.,2, 124–233.
——, and A. Xie, 1988: Westward propagating low-frequency oscillation and its teleconnections in the eastern hemisphere. Acta Meteorol. Sin.,2, 300–312.
Chen, T.-C., and M. Murakami, 1988: The 30–50-day variation of convective activity over the western Pacific Ocean with the emphasis on the northwestern region. Mon. Wea. Rev.,116, 892–906.
——, and M. C. Yen, 1991: Interaction between intraseasonal oscillations of the midlatitude flow and tropical convection during 1979 northern summer: The Pacific Ocean. J. Climate,4, 653–671.
Ding, Y.-H., 1992: Summer monsoon rainfall in China. J. Meteor. Soc. Japan,70, 373–396.
Gill, A. E., 1980: Some simple solutions for heat induced tropical circulation. Quart. J. Roy. Meteor Soc.,106, 447–463.
Hartmann, D. L., M. L. Michelson, and S. A. Klein, 1992: Seasonal variations of tropical intraseasonal oscillations: A 20–25-day oscillation in the western Pacific. J. Atmos. Sci.,49, 1277–1289.
Hendon, H., and B. Liebmann, 1990: The intraseasonal (30–50-day) oscillation of the Australian summer monsoon. J. Atmos. Sci.,47, 2909–2923.
Holland, G. J., 1986: Interannual variability of the Australian monsoon at Darwin: 1952–1982. Mon. Wea. Rev.,114, 594–604.
——, 1995: Scale interaction in the western Pacific monsoon. Meteor. Atmos. Phys.,56, 57–79.
Huang, R. H., 1994: Interactions between the 30–60-day oscillation, the Walker circulation and the convective activities in the tropical western Pacific and their relations to the interannual oscillation. Adv. Atmos. Sci.,11, 367–384.
Kawamura, R., T. Yasunari, and H. Ueda, 1994: Abrupt changes of seasonal evolution of large-scale convective activity and tropical cyclone over the western Pacific (in Japanese). Rep. Nat. Res. Institute for Earth Science and Disaster Prevention,53, 1–18.
——, T. Murakami, and B. Wang, 1997: Tropical and midlatitude 45-day perturbations during the northern summer. J. Meteor. Soc. Japan., in press.
Krishnamurti, T. N., 1985: Summer monsoon experiment—A review. Mon. Wea. Rev.,113, 1590–1626.
——, and H. N. Bhalme, 1976: Oscillations of a monsoon system. Part I. Observational aspects. J. Atmos. Sci.,33, 1937–1954.
——, and D. Subrahmanyan, 1982: The 30–50-day mode at 850 mb during MONEX. J. Atmos. Sci.,39, 2088–2095.
Lau, K.-M., and P. H. Chan, 1986: Aspects of 40–50-day oscillation during the northern summer as inferred from outgoing longwave radiation. Mon. Wea. Rev.,114, 1354–1367.
Liebmann, B., and D. L. Hartmann, 1984: An observational study of tropical–midlatitude interaction on intraseasonal timescales during winter. J. Atmos. Sci.,41, 3333–3350.
Livezey, R. E., and W. Y. Chen, 1983: Statistical field significance and its determination by Monte Carlo techniques. Mon. Wea. Rev.,111, 46–59.
Madden, R. A., 1986: Seasonal variations of the 40–50-day oscillation in the tropics. J. Atmos. Sci.,43, 3138–3158.
Matsumoto, J., 1992: The seasonal changes in Asian and Australian monsoon regions. J. Meteor. Soc. Japan,70, 257–273.
McBride, J. L., 1987: The Australian summer monsoon. Monsoon Meteorology, C. P. Chang and T. N. Krishnamurti, Eds., Oxford University Press, 203–231.
Murakami, T., 1980: Temporal variation of satellite-observed outgoing longwave radiation. Part I: Long-period (15–30-day) observations. Mon. Wea. Rev.,108, 408–426.
——, and J. Matsumoto, 1994: Summer monsoon over the Asian continent and the western North Pacific. J. Meteor. Soc. Japan,72, 719–745.
——, L.-X. Chen, and A. Xie, 1986: Relationship among seasonal cycle, low-frequency oscillation, and transient disturbances as revealed from outgoing longwave radiation data. Mon. Wea. Rev.,114, 1456–1465.
Nakazawa, T., 1992: Seasonal phase lock of intraseasonal variation during the Asian summer monsoon. J. Meteor. Soc. Japan,70, 597–611.
Ninomiya, K., and T. Murakami, 1987: The early summer rainy season (Baiu) over Japan. Monsoon Meteorology, C.-P. Chang and T. N. Krishnamurti, Eds., Oxford University Press, 93–121.
Rao, Y. P., 1976: Southwest monsoon. Synoptic Meteorology, Meteor. Monogr., No. 1/1976, India Meteor. Dept., 367 pp.
Sadler, J. C., 1976: A role of the tropical upper tropospheric trough in early season typhoon development. Mon. Wea. Rev.,104, 1266–1278.
Sikka, D. R., and S. Gadgel, 1980: On the maximum cloud zone and ITCZ over Indian longitudes during the southwest monsoon. Mon. Wea. Rev.,108, 1840–1853.
Tanaka, M., 1992: Intraseasonal oscillation and the onset and retreat dares of the summer monsoon over east, southeast Asia and the western Pacific region using GMS high cloud amount data. J. Meteor. Soc. Japan,70, 613–629.
Tao, S., and L.-X. Chen, 1987: A review of recent research on the east Asian summer monsoon in China. Monsoon Meteorology, C.-P. Chang and T. N. Krishnamurti, Eds., Oxford University Press, 60–92.
Ueda, H., T. Yasunari, and R. Kawamura, 1995: Abrupt seasonal change of large-scale convection activity over the western Pacific in northern summer. J. Meteor. Soc. Japan,73, 795–809.
Wang, B., 1994: Climatic regimes of tropical convection and rainfall. J. Climate,7, 1109–1118.
——, and H. Rui, 1990: Synoptic climatology of transient tropical intraseasonal convection anomalies: 1975–1985. Meteor. Atmos. Phys.,44, 43–62.
——, and Y.-H. Ding, 1992: An overview of the Madden–Julian oscillation and its relation to monsoon and mid-latitude circulation. Adv. Atmos. Sci.,9, 93–111.
——, and X. Xie, 1996: Low-frequency equatorial waves in vertically sheared zonal flow. Part I: Stable waves. J. Atmos. Sci.,53, 449–467.
Webster, P. J., 1972: The response of the tropical atmosphere to local study forcing. Mon. Wea. Rev.,100, 518–541.
——, and S. Yang, 1992: Monsoon and ENSO: Selectively interactive systems. Quart. J. Roy. Meteor. Soc.,118, 877–926.
Xie, X., and B. Wang, 1996: Low-frequency equatorial waves in vertically sheared zonal flow. Part II: Unstable waves. J. Atmos. Sci.,53, 3589–3605.
Yanai, M., and C. Li, 1994: Mechanisms of heating and the boundary layer over the Tibetan Plateau. Mon. Wea. Rev.,122, 305–323.
Yasunari, T., 1979: Cloudiness fluctuations associated with the Northern Hemisphere summer monsoon. J. Meteor. Soc. Japan,57, 227–242.
——, 1980: A quasi-stationary appearance of 30–40-day period in the cloudiness fluctuation during the summer monsoon over India. J. Meteor. Soc. Japan,58, 225–227.
Zeng, Q.-C., B.-L. Zhang, Y.-L. Liang, and S.-X. Zhao, 1994: East Asian summer monsoon—A case study. Proc. Indian Nat. Sci. Acad.,60A, 81–96.
Zhu, B.-Z., 1988: Origin and properties of the east Asian summer monsoon. Preprint, Int. Conf. on Tropical Meteorology, Brisbane, Australia.
——, and B. Wang, 1993: The 30–60-day convection seesaw between the tropical Indian and western Pacific Oceans. J. Atmos. Sci.,50, 184–199.