17 The relationship between the boreal summer intraseasonal oscillation (BSISO) in the 18 tropics and the summertime tropical-extratropical teleconnection called the Pacific-Japan 19 (PJ) pattern is investigated. The positive correlation between the BSISO and intraseasonal 20 PJ pattern peaks during BSISO phase 8 when the convective center of the BSISO reaches 21 Seiki et al., Intraseasonal relationship between the BSISO and the PJ pattern 2 the vicinity of the Philippines. A composite analysis

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... based on the BSISO events shows 22 that intraseasonal responses to the migration of the BSISO extend to the midlatitudes and 23 form circulation anomalies reminiscent of the PJ pattern. During phases 7-8, cyclonic 24 wind anomalies with low-pressure signals drastically intensify north of the Philippines 25 and southeasterly wind anomalies blow into midlatitude East Asia, influencing the 26 summer climate. Other apparent intraseasonal signals in pressure and surface air 27 temperature are found over the midlatitude central Pacific and eastern Eurasia, 28 respectively. The intraseasonal variability in the PJ pattern associated with the BSISO 29 undergoes strong interannual modulations, with enhanced intraseasonal signals in 30 summers of the positive seasonal-mean PJ pattern and suppressed signals in those of the 31 negative PJ pattern. This asymmetry between the positive and negative PJ summers 32 highlights the importance of cross-scale interactions for a better understanding of summer 33 climate in East Asia. 34 35