ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 42 Issue 9 > 2016,42(9):1069-1078. DOI:10.7519/j.issn.1000-0526.2016.09.004 Prev Next
Analysis on Features of Tropical Cyclone Activities over the Western North Pacific in 2015 and Their Variations Associated with Strong El Nino
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Abstract:
Based on the CMASTI tropical cyclone best track data from 1951 to 2015, the tropical cyclones activities over the Western North Pacific (including the South China Sea) in strong El Ni〖AKn~D〗o years are analyzed. The features of tropical cyclones in 2015 and their corresponding atmospheric circulation characteristics are discussed as well, for the year 2015 is the strongest El Ni〖AKn~D〗o year since 1997. The results show that in strong El Ni〖AKn~D〗o years, there are a larger number of TCs in the first half of the year and smaller number of TCs from June to October, and fewer TCs land in the whole year. The TC genesis is to the southeast of its normal and they tend to recurve from northwestward to northeastward. TC activity in 2015 is in accordance with the laws above. There is a largescale anomalous westerly over the western equatorial Pacific before El Ni〖AKn~D〗o gets mature, and a strong El Ni〖AKn~D〗o weakens the Walker circulation. Both of them suppress the convection. Besides, the subtropical high is located further south, making the ITCZ move southward. All these factors result in fewer TCs in 2015. In strong El Ni〖AKn~D〗o year, the strength of all the TCs is stronger, and this is due to the weaker intensity and smaller area of the subtropical high. There are more TCs forming in the southeast part of the WNP with stronger intensity, and the number and intensity of TCs in the northeast part is in the opposite condition; TCs generating in the SCS is fewer and weaker than normal as well. The TC activity characteristics in 2015 accord with the above rules and they are attributed to the eastward western ridge point of subtropical high and an anomalous northwesterly over the WNP at 500 hPa.
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