Lee, D. Y., J.-Y. Lee, Y.-M. Yang, P.-C. Hsu, and A-Y. Lim, 2025: Modulation of 10–30-day boreal summer intraseasonal oscillation and the associated rainfall events by El Niño. Adv. Atmos. Sci., https://doi.org/10.1007/s00376-025-4170-x.
Citation: Lee, D. Y., J.-Y. Lee, Y.-M. Yang, P.-C. Hsu, and A-Y. Lim, 2025: Modulation of 10–30-day boreal summer intraseasonal oscillation and the associated rainfall events by El Niño. Adv. Atmos. Sci., https://doi.org/10.1007/s00376-025-4170-x.

Modulation of 10–30-day Boreal Summer Intraseasonal Oscillation and Associated Rainfall Events by El Niño

  • Daily precipitation anomalies in the western North Pacific (WNP) and East Asia (EA) exhibit significant intraseasonal variability, peaking at 10–30-day time scales. It has been suggested that boreal summer intraseasonal oscillation (BSISO) on 30–60-day time scales is strongly modulated by El Niño–Southern Oscillation (ENSO) with stronger intensity and propagation during La Niña compared to El Niño summers, but the dependency of 10–30-day BSISO on ENSO has not been well understood. Here, we show that the intensity and northward propagation of the 10–30-day BSISO convection over the WNP-EA region are stronger and more organized during El Niño developing summers than other summers, including neutral summers. During El Niño developing summers, the BSISO-induced precipitation and low-level circulation tend to exhibit a stronger meridional tripolar pattern than those during neutral summers. We highlight that the strengthening of 10–30-day BSISO northward propagation and associated rainfall anomalies over EA in El Niño developing summers is contributed by not only the previously proposed stronger air–sea interaction with a larger meridional gradient of sea surface temperature, but also an enhanced dynamic process with stronger relative vorticity and moisture convergence.
  • loading

Catalog

    Turn off MathJax
    Article Contents

    /

    DownLoad:  Full-Size Img  PowerPoint
    Return
    Return