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| Occurrences of Wintertime Tropical Cyclones in the Western North Pacific under the Background of Global Warming |
| HE Jie-Lin,GUAN Zhao-Yong,QIAN Dai-Li,WAN Qi-Lin,WANG Li-Juan |
| Key Laboratory of Meteorological Disaster of Ministry of Education，Nanjing University of Information Science &Technology, Nanjing 210044; Yulin City Meteorological Bureau of Guangxi, Yulin 537000,Key Laboratory of Meteorological Disaster of Ministry of Education，Nanjing University of Information Science &Technology, Nanjing 210044,Key Laboratory of Meteorological Disaster of Ministry of Education，Nanjing University of Information Science &Technology, Nanjing 210044,Key Laboratory of Meteorological Disaster of Ministry of Education，Nanjing University of Information Science &Technology, Nanjing 210044; Guangzhou Institute of Tropical and Oceanic Meteorology, CMA, Guangzhou 510080,Key Laboratory of Meteorological Disaster of Ministry of Education，Nanjing University of Information Science &Technology, Nanjing 210044 |
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Abstract Using tropical cyclone (TC) observations over a 58-yr period (19492006) from the China Meteorological Administration, the 40-year ECMWF Reanalysis (ERA-40), NCEP-NCAR reanalysis, and the Hadley Centre sea ice and sea surface temperature (HadISST) datasets, the authors have examined the behaviors of tropical cyclones (TCs) in the western north Pacific (WNP) in boreal winter (November-December-January-February). The results demonstrate that the occurrences of wintertime TCs, including super typhoons, have decreased over the 58 years. More TCs are found to move westward than northeastward, and the annual total number of parabolic-track-type TCs is found to be decreasing. It is shown that negative sea surface temperature anomalies (SSTAs) related to La Niña events in the equatorial central Pacific facilitate more TC genesis in the WNP region. Large-scale anomalous cyclonic circulations in the tropical WNP in the lower troposphere are observed to be favorable for cyclogenesis in this area. On the contrary, the positive SSTAs and anomalous anticyclonic circulations that related to El Niño events responsible for fewer TC genesis. Under the background of global warming, the western Pacific subtropical high tends to intensify and to expand more westward in the WNP, and the SSTAs display an increasing trend in the equatorial eastern-central Pacific. These climate trends of both atmospheric circulation and SSTAs affect wintertime TCs, inducing fewer TC occurrences and causing more TCs to move westward.
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Received: 12 August 2009
Revised: 09 October 2009
Accepted: 19 October 2009
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