Boreal Summer Extratropical Intraseasonal Waves over the Eurasian Continent and Real-Time Monitoring Metrics

Abstract Boreal summer extratropical intraseasonal oscillation (EISO) is crucial in modulating regional subseasonal variation and particularly causing extreme meteorological events, but it has yet to be well clarified operationally monitored. This study first objectively sorts out three dominant EISOs trapped along two westerly jet streams over Eurasia, then proposes the corresponding real-time metrics. The are (i) an 8–25-day eastward-propagating wave subtropical (EISO-SJE) initiating at exit of North America–North Atlantic strengthening Black Sea–Caspian Sea–arid central Asia region; (ii) a 10–30-day eastward-traveling polar front (EISO-PJE), starting near Scandinavia enhancing from East European Plain West Siberian decaying Okhotsk (iii) 10–40-day westward-migrating (EISO-PJW), which enhances Ural Mountains weakens Scandinavia. metrics then, following EISOs, have been constructed, they able capture spatiotemporal features application. Moreover, close linkages between these extremes/the blocking occurrence clearly demonstrated, confirming importance EISO Together with tropical oscillation, this provides subseasonal-to-seasonal (S2S) community well-portrayed unified picture waves for monitoring boreal signals Eurasia facilitate predictions. Significance Statement drawn increasing attention owing its triggering weather events affecting prediction. However, despite urgent need community, comprehensive delineation diversity remain gap knowledge. comprehensively clarifies Eurasia. More importantly, constructed based on applicable operational monitoring, prediction, model evaluation. stimulates focus S2S as complementary component addition MJO’s teleconnection mid- high latitudes.