Editorial Type:
Article
Article Type:
Research Article

Interannual Variations of the Boreal Summer Intraseasonal Oscillation in the Asian–Pacific Region

Haiyan Teng Department of Meteorology, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, Hawaii

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Bin Wang Department of Meteorology, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, Hawaii

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Print Publication:
15 Nov 2003
DOI:
https://doi.org/10.1175/1520-0442(2003)016<3572:IVOTBS>2.0.CO;2
Page(s):
3572–3584
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Abstract

A finite-domain wavenumber–frequency analysis was proposed to objectively measure the interannual variability of the boreal summer intraseasonal oscillation (ISO) in the Asian–Pacific region. The strongest interannual variations of the ISO are found in the off-equatorial western North Pacific (WNP). In summers when El Niño is developing, both the westward- and northward-propagating waves with periods of 15–40 and 8–10 days are enhanced in July–October. The northward-propagating ISO in the Indian summer monsoon region, however, has little linkage with El Niño–Southern Oscillation (ENSO).

ENSO affects the northwestward-propagating ISO mode in the WNP through changing the mean circulation. During July–October in the El Niño developing year, the easterly vertical shears over the tropical western Pacific are considerably increased, which in turn promote development and northwestward emanation of Rossby waves away from the equatorial western-central Pacific, reinforcing the WNP ISO. In the Indian summer monsoon region, the ENSO-induced circulation changes are too weak to significantly modify the strong easterly sheared monsoon mean circulation. Therefore, the northward-propagating ISO is insensitive to ENSO.

Unlike the wintertime Madden–Julian oscillation (MJO), which is uncorrelated with ENSO, the May–July MJO is strengthened during El Niño developing years. The questions of why there is a seasonal dependence of the MJO–ENSO relationship and how ENSO directly affects the May–July MJO require further investigations.

Corresponding author address: Haiyan Teng, Department of Meteorology, University of Hawaii at Manoa, 2525 Correa Road, Honolulu, HI 96822. Email: hteng@hawaii.edu

Abstract

A finite-domain wavenumber–frequency analysis was proposed to objectively measure the interannual variability of the boreal summer intraseasonal oscillation (ISO) in the Asian–Pacific region. The strongest interannual variations of the ISO are found in the off-equatorial western North Pacific (WNP). In summers when El Niño is developing, both the westward- and northward-propagating waves with periods of 15–40 and 8–10 days are enhanced in July–October. The northward-propagating ISO in the Indian summer monsoon region, however, has little linkage with El Niño–Southern Oscillation (ENSO).

ENSO affects the northwestward-propagating ISO mode in the WNP through changing the mean circulation. During July–October in the El Niño developing year, the easterly vertical shears over the tropical western Pacific are considerably increased, which in turn promote development and northwestward emanation of Rossby waves away from the equatorial western-central Pacific, reinforcing the WNP ISO. In the Indian summer monsoon region, the ENSO-induced circulation changes are too weak to significantly modify the strong easterly sheared monsoon mean circulation. Therefore, the northward-propagating ISO is insensitive to ENSO.

Unlike the wintertime Madden–Julian oscillation (MJO), which is uncorrelated with ENSO, the May–July MJO is strengthened during El Niño developing years. The questions of why there is a seasonal dependence of the MJO–ENSO relationship and how ENSO directly affects the May–July MJO require further investigations.

Corresponding author address: Haiyan Teng, Department of Meteorology, University of Hawaii at Manoa, 2525 Correa Road, Honolulu, HI 96822. Email: hteng@hawaii.edu

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  • Annamalai, H., and J. M. Slingo, 2001: Active/break cycles: Diagnosis of the intraseasonal variability of the Asian summer monsoon. Climate Dyn., 18 , 85–102.

    • Search Google Scholar
    • Export Citation

  • Anyamba, E. K., and B. C. Weare, 1995: Temporal variability of the 40–50 day oscillation in tropical convection. Int. J. Climatol., 15 , 379–402.

    • Search Google Scholar
    • Export Citation

  • Chen, T-C., and S-P. Weng, 1999: Interannual and intraseasonal variations in monsoon depressions and their westward-propagating predecessors. Mon. Wea. Rev., 127 , 1005–1020.

    • Search Google Scholar
    • Export Citation

  • Fink, A., and E. Speth, 1997: Some potential forcing mechanisms of the year-to-year variability of the tropical convection and its intraseasonal (25–70-day) variability. Int. J. Climatol., 17 , 1513–1534.

    • Search Google Scholar
    • Export Citation

  • Frank, W. M., 1987: Tropical cyclone formation. A Global View of Tropical Cyclones, R. L. Elsberry et al., Eds., University of Chicago Press, 53–90.

    • Search Google Scholar
    • Export Citation

  • Gutzler, D. S., 1991: Interannual fluctuations of intraseasonal variance of near-equatorial zonal winds. J. Geophys. Res., 96 , 3173–3185.

    • Search Google Scholar
    • Export Citation

  • Hayashi, Y., 1982: Space–time spectral analysis and its applications to atmospheric waves. J. Meteor. Soc. Japan, 60 , 156–171.

  • Hendon, H., C. Zhang, and J. Glick, 1999: Interannual variation of the Madden–Julian Oscillation during austral summer. J. Climate, 12 , 2538–2550.

    • Search Google Scholar
    • Export Citation

  • Kalnay, E., and Coauthors. 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437–471.

  • Kemball-Cook, S., and B. Wang, 2001: Equatorial waves and air–sea interaction in the boreal summer intraseasonal oscillation. J. Climate, 14 , 2923–2942.

    • Search Google Scholar
    • Export Citation

  • Kessler, W. S., 2001: EOF representations of the Madden–Julian Oscillation and its connection with ENSO. J. Climate, 14 , 3055–3061.

  • Kessler, W. S., and M. J. McPhaden, 1995: Oceanic equatorial waves and the 1991–93 El Niño. J. Climate, 8 , 1757–1776.

  • Krishnamurti, T. N., and P. Ardanuy, 1980: The 10- to 20-day westward propagating mode and “breaks in the Monsoons.”. Tellus, 32 , 15–26.

    • Search Google Scholar
    • Export Citation

  • Krishnamurti, T. N., and D. Subrahmanyam, 1982: The 30–50 day mode at 850 mb during MONEX. J. Atmos. Sci., 39 , 2088–2095.

  • Lau, K-H., and N-C. Lau, 1990: Observed structure and propagation characteristics of tropical summertime synoptic scale disturbances. Mon. Wea. Rev., 118 , 1888–1913.

    • Search Google Scholar
    • Export Citation

  • Lau, K-M., and P. H. Chan, 1986: Aspects of the 40–50 day oscillation during the northern summer as inferred from outgoing longwave radiation. Mon. Wea. Rev., 114 , 1354–1367.

    • Search Google Scholar
    • Export Citation

  • Li, T., and B. Wang, 1994: The influence of sea surface temperature on the tropical intraseasonal oscillation: A numerical study. Mon. Wea. Rev., 122 , 2349–2362.

    • Search Google Scholar
    • Export Citation

  • Liebmann, B., and C. A. Smith, 1996: Description of a complete (interpolated) outgoing longwave radiation dataset. Bull. Amer. Meteor. Soc., 77 , 1275–1277.

    • Search Google Scholar
    • Export Citation

  • LinHo, and B. Wang, 2002: The time–space structure of the Asian–Pacific summer monsoon: A fast annual cycle view. J. Climate, 15 , 2001–2019.

    • Search Google Scholar
    • Export Citation

  • Madden, R. A., and P. R. Julian, 1971: Detection of a 40–50 day oscillation in the zonal wind in the tropical Pacific. J. Atmos. Sci., 28 , 702–708.

    • Search Google Scholar
    • Export Citation

  • Madden, R. A., and P. R. Julian, 1972: Description of global-scale circulation cells in the Tropics with a 40–50 day period. J. Atmos. Sci., 29 , 1109–1123.

    • Search Google Scholar
    • Export Citation

  • Matsuno, T., 1966: Quasi-geostrophic motions in the equatorial area. J. Meteor. Soc. Japan, 44 , 25–43.

  • Mehta, A. V., and T. N. Krishnamurti, 1988: Interannual variability of the 30 to 50 day wave motions. J. Meteor. Soc. Japan, 66 , 535–547.

    • Search Google Scholar
    • Export Citation

  • Murakami, T., T. Nakazawa, and J. He, 1984: On the 40–50 day oscillation during the 1979 Northern Hemisphere summer. J. Meteor. Soc. Japan, 62 , 440–468.

    • Search Google Scholar
    • Export Citation

  • Nitta, T., 1987: Convective activities in the tropical western Pacific and their impact on the Northern Hemisphere summer circulation. J. Meteor. Soc. Japan, 65 , 373–389.

    • Search Google Scholar
    • Export Citation

  • Salby, M. L., and H. H. Hendon, 1994: Intraseasonal behavior of clouds, temperature, and motion in the Tropics. J. Atmos. Sci., 51 , 2207–2224.

    • Search Google Scholar
    • Export Citation

  • Schrage, J., and D. G. Vincent, 1996: Tropical convection on 7–21-day timescales over the western Pacific. J. Climate, 9 , 587–607.

  • Slingo, J. M., D. P. Rowell, K. R. Sperber, and F. Nortley, 1999: On the predictability of the interannual behavior of the Madden–Julian oscillation and its relationship with El Niño. Quart. J. Roy. Meteor. Soc., 125 , 583–609.

    • Search Google Scholar
    • Export Citation

  • Vernekar, A. D., V. Thapliyal, R. H. Kripalani, S. V. Sigh, and B. Kirtman, 1993: Global structure of the Madden–Julian Oscillations during two recent contrasting summer monsoon seasons over India. Meteor. Atmos. Phys., 52 , 37–47.

    • Search Google Scholar
    • Export Citation

  • von Storch, H., and F. W. Zwiers, 1999: Statistical Analysis for Climate Research. Cambridge University Press, 484 pp.

  • Wang, B., and H. Rui, 1990: Synoptic climatology of transient tropical intraseasonal convection anomalies: 1975–1985. Meteor. Atmos. Phys., 44 , 43–61.

    • Search Google Scholar
    • Export Citation

  • Wang, B., and X. Xie, 1996: Low-frequency equatorial waves in vertically sheared zonal flow. Part I: Stable waves. J. Atmos. Sci., 53 , 449–467.

    • Search Google Scholar
    • Export Citation

  • Wang, B., and X. Xie, 1997: A model for the boreal summer intraseasonal oscillation. J. Atmos. Sci., 54 , 72–86.

  • Wang, B., and Z. Fan, 1999: Choice of South Asian summer monsoon indices. Bull. Amer. Meteor. Soc., 80 , 629–638.

  • Wheeler, M., and G. N. Kiladis, 1999: Convectively coupled equatorial waves: Analysis of clouds and temperature in the wavenumber–frequency domain. J. Atmos. Sci., 56 , 374–399.

    • Search Google Scholar
    • Export Citation

  • Wilks, D. S., 1995: Statistical Methods in the Atmospheric Sciences. Academic Press, 467 pp.

  • Xie, P., and P. A. Arkin, 1997: Global precipitation: A 17-year monthly analysis based on gauge observations, satellite estimates and numerical model outputs. Bull. Amer. Meteor. Soc., 78 , 2539–2558.

    • Search Google Scholar
    • Export Citation

  • 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.

    • Search Google Scholar
    • Export Citation

  • Yasunari, T., 1979: Cloudiness fluctuations associated with the Northern Hemisphere summer monsoon. J. Meteor. Soc. Japan, 57 , 227–242.

    • Search Google Scholar
    • Export Citation

  • Yasunari, T., 1980: A quasi-stationary appearance of 30 to 40 day period in the cloudiness fluctuations during the summer monsoon over India. J. Meteor. Soc. Japan, 58 , 225–229.

    • Search Google Scholar
    • Export Citation
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