Serial Clustering of Tibetan Plateau Vortices and Its Relationship With Atmospheric Quasi-Biweekly Oscillation Revealed by a Database Derived From Multiple Reanalysis

Tibetan Plateau vortices (TPVs) are the major precipitation-producing weather system, which dominates the water supplies over the TP. Serial clustering is one of the basic features of TPVs and is closely related to the atmospheric intraseasonal oscillation of the TP. Through a database of TPVs derived from multiple reanalysis data sets, we investigated the spatiotemporal characteristics of TPV clustering (TPVC) and its connection with the atmospheric quasi-biweekly oscillation (QBWO). The TPV tracks from variant reanalysis data sets reproduced consistent features for TPVC. The database revealed that the TPVC primarily occurs during the warm season and exhibits significant interannual variability. TPV clustering frequently occurs during the positive phase of the QBWO, in which the TP emerges cyclonic anomalies at lower atmospheric levels and anticyclonic anomalies at upper levels. This configuration creates a baroclinic structure that favors the formation of TPVCs. Conversely, the negative phase of QBWO results in an inverse atmospheric anomaly pattern, reducing TPVC occurrences. The interannual variability of TPVCs is primarily influenced by the amplitude of relative vorticity rather than the frequency of positive or negative phases. Furthermore, there are distinct differences in circulation patterns between years with high and low TPVC frequencies. In high-TPVC (low-TPVC) years, the lower levels of the TP predominantly show positive (negative) vorticity anomalies, accompanied by an anticyclone (cyclone) in the northern TP and a cyclone (anticyclone) in the eastern TP, while an anti-cyclonic (cyclonic) anomaly is active over the TP that indicates an intensified (weakened) South Asian High.