Global Teleconnections of Extreme Rainfall Events in the Yellow River Basin

Extreme rainfall events (EREs) frequently hit the middle-lower reaches of the Yellow River basin (YRB) during boreal summer. Recent observations have indicated that EREs exhibit teleconnection patterns across long spatial distances. This study investigated ERE teleconnections in the YRB using the Event Synchronization (ES) method in combination with Complex Networks (CN) theory. EREs in the YRB are significantly synchronized with other regions from regional to global scales. Additionally, high-resolution CMIP6 models in general show better skills in capturing these characteristics compared to low-resolution models. A further examination shows that the spatial synchronization patterns exhibiting pronounced time-scale dependence. Significant ERE synchronizations between the YRB and Europe were uncovered, where the YRB lags Eastern Europe by 3-5 days and Western Europe by 5-7 days, with Rossby wave propagation playing a key role. Wave trains from Europe propagate downstream along the Eurasian jet, inducing anomalous circulations over the YRB that enhance vertical upward motion and moisture transport, ultimately triggering EREs. Two distinct wave trains are observed: one is associated with Eastern Europe-YRB synchronization, occurring in the mid-latitude region; the other one is linked to Western Europe-YRB synchronization, positioned at higher latitudes. Notably, 17.5% of Eastern Europe-YRB synchronization cases and 17.0% of Western Europe-YRB cases overlap. Quantitative analysis indicates that the synchronized events between Eastern (Western) Europe and the YRB account for roughly 28% (30%) of EREs in the YRB. These findings are critical for better understanding ERE mechanisms, offering guidance for forecasting and early warning capabilities for EREs in the YRB.