[1] Understanding the origin and perpetuation of the monsoon cycle has eluded scientists for decades. Using a suite of unprecedented satellite measurements, we show that the antecedents of the active/break monsoon emerge in the western equatorial Indian Ocean (EIO). The initiation of a new rainy phase in the western EIO is preceded by in situ surface wind convergence and central EIO warming, both are induced by the subdued condition over the eastern EIO set up in the previous cycle. Thus, a selfinduction mechanism appears to be operating in maintenance of the Indian monsoon intraseasonal oscillation. The finding here offers a focus for prediction of the active/break Indian monsoon with potential predictability about four weeks in advance. Citation: Wang, B., P. J. Webster, and H. Teng (2005), Antecedents and self-induction of active-break south Asian monsoon unraveled by satellites, Geophys. Res. Lett., 32, L04704,

Track nonlinear energy sinks (track NESs) have been shown to be an effective and applicable strategy to mitigate structural response in recent years. However, previous studies on track NESs has mainly focused on demonstrating the benefits of track NESs through numerical simulations and experiments, with relatively little attention paid to the analytical understanding of the unique dynamics of track NESs. This study analyzes the responses of a track NES when subjected to impulsive and harmonic excitations by the harmonic balance method. Special attention is given to the cause and effect of the peaking behavior that is a prominent characteristic of the track NES's restoring forcedisplacement relationship. Analytical results reveal that the special energy-frequency characteristics of track NESs can be, at times, utilized to enhance the energy robustness that is absent in the conventional cubic NESs. Based on the analytical response expression, an equivalent linearization method (ELM) for the track NESs is developed for stochastic analysis. This ELM is numerically validated on the systems with strong nonlinearities. Stochastic optimization built on the ELM is performed to obtain design parameters of the track NES that can lead to minimum response variances of the primary structure. In particular, the proposed optimization procedure can be applied to seismic optimum design in which the seismic excitations are modeled as filtered whitenoise ground motions. The analytical techniques provided in this study lay the groundwork for the practical implementation of track NESs as a robust and effective control strategy for engineering structures. K E Y W O R D Sharmonic balance method, harmonic excitation, impulsive excitation, peaking behavior, stochastic optimization, track nonlinear energy sink

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