Abstract
Maintenance of the anomalous anticyclone (cyclone) over the Philippine Sea following strong peak El Niño (La Niña) leads to a negative correlation between the pre-winter (October–December) El Niño-Southern Oscillation (ENSO) index and the tropical cyclone (TC) genesis frequency in the ensuing early TC season (January–June). This negative lead-lag correlation has established the predictability of the western North Pacific (WNP) TC genesis frequency in the early season. However, little is known about whether this relationship remains steady to date, especially in the context of evolving features of ENSO in recent decades. Here we show that the negative relationship experiences an abrupt breakdown around the early 2000s (1999–2006), which primarily occurs in the southeastern quadrant of the WNP. During the breakdown period, the anomalous anti-cyclone shifts westward to the South China Sea and an anomalous cyclonic circulation occupies the southeastern quadrant of the WNP, causing enhanced TC formation. We further reveal that the westward displacement of the WNP anticyclonic anomaly during 1999–2006 is induced by the westward shift of sea surface temperature (SST) and associated precipitation anomalies during the decaying phase of ENSO, which increases cyclonic circulation and ascending motion while reduces vertical wind shear, and thereby enhances TC formation over the southeastern WNP. The results suggest that the frequent occurrence of decaying ENSO events with SST anomaly center over the central Pacific (CP) accounts for the abrupt breakdown of predictability, and the impacts of ENSO on TC formation in the early TC season are sensitive to the location of the maximum SST anomaly. Distinguishing eastern Pacific (EP) and CP types of ENSO and/or strong and weak ENSO events may help to improve the early season TC genesis forecast over the WNP. The results also have important implications for understanding the future projection of TC changes under global warming scenarios.
| Original language | English |
|---|---|
| Pages (from-to) | 3809-3822 |
| Number of pages | 14 |
| Journal | Climate Dynamics |
| Volume | 52 |
| Issue number | 7-8 |
| DOIs | |
| State | Published - Apr 15 2019 |
Funding
This study is supported by the Atmosphere–Ocean Research Center (AORC). The AORC is partially funded by the Nanjing University of Information Science and Technology (NUIST). This research is jointly supported by the National Basic Research Program of China (Grant No. 2015CB452803), the National Natural Science Foundation of China (Grant Nos. 41420104002, 41730961, 41675051 and 41705060), the National Key Research and Development Program of China (Grant No. 2016YFA0600401), the Natural Science Foundation of Jiangsu Province (Grant No. BK20170941), the Startup Foundation for Introducing Talent of NUIST (Grant No. 2016r048), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD). The authors also thank anonymous reviewers for the constructive comments that led to significant improvement of the original manuscript. This is the NUIST-Earth System Modeling Center (ESMC) publication number 226, the School of Ocean and Earth Science and Technology (SOEST) publication number 10416, and the IPRC publication number 1328. Fig. 11 Seasonal evolutions from OND(0) to AMJ(1) of regressed SST (shading) and 850 hPa wind anomalies for negatively correlated years (a–c) and positively correlated years (d–f) with respect to OND Niño 3.4 index. The numerals in parentheses denote the ENSO devel- Acknowledgements This study is supported by the Atmosphere–Ocean Research Center (AORC). The AORC is partially funded by the Nanjing University of Information Science and Technology (NUIST). This research is jointly supported by the National Basic Research Program of China (Grant No. 2015CB452803), the National Natural Science Foundation of China (Grant Nos. 41420104002, 41730961, 41675051 and 41705060), the National Key Research and Development Program of China (Grant No. 2016YFA0600401), the Natural Science Foundation of Jiangsu Province (Grant No. BK20170941), the Startup Foundation for Introducing Talent of NUIST (Grant No. 2016r048), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD). The authors also thank anonymous reviewers for the constructive comments that led to significant improvement of the original manuscript. This is the NUIST-Earth System Modeling Center oping (0) and decaying (1) years. The grey lines denote 140°E. A denotes the anti-cyclonic circulation and C denotes the cyclonic circulation (ESMC) publication number 226, the School of Ocean and Earth Science and Technology (SOEST) publication number 10416, and the IPRC publication number 1328.