THE IMPACT OF TROPICAL CYCLONES ON CHINA IN 2016

In 2016, the Northwest Pacific and the South China Sea registered the genesis of 26 tropical cyclones. 8 of them, including NEPARTAK(1601), MIRINAE(1603), NIDA(1604), DIANMU(1608), MERANTI(1614),MEGI(1617), SARIKA(1621) and HAIMA(1622), made landfall over China's coastal areas. The number one TC of 2016, NEPARTAK, was named on July 3. Although no typhoon generated in the first half of this year,which means 4.6 incidences less compared with the same period of a normal year, more tropical cyclones made landfall over China(the historical average in the same period of 1949-2015 is 6.7). And these 8 tropical cyclones had an averaged intensity up to 40.6 m/s, significantly enhanced compared with the multi-year average of 32.8 m/s.The death toll from the 11 tropical cyclones affected China in 2016 is 206. MERANTI was the most destructive one in 2016, which brought up the largest numbers of affected and evacuated population, damaged houses and direct economic losses. In 2016, China Meteorological Administration(CMA) 24-120 h mean official track forecast errors were 66, 127, 213, 292 and 364 km, respectively. The 24 h track forecast error has been kept within 70 km in two consecutive years.

Application of high-level environmental field factor in TC's sudden recurvature process

Using the 6-hourly reanalysis data of European Center ERA-Interim with horizontal resolution of 0.25°×0.25°and hourly typhoon operational data provided by the CMA(China Meteorological Administration),a new high-level environmental field factor is derived,and its application during the recurvature period of No.14 Typhoon Yagi and No.18 Typhoon Rumbia in 2018 is compared and analyzed.According to the comparison study,there is always a clear positive abnormal value area of high-level environmental field factor on the northeast of Rumbia during its northward movement,implying an obvious alteration of ∇·u and a big negative gradient of ∇u on the northeast of Rumbia.With the eastward movement of the westerly trough and the strengthening of the subtropical westerly jet,Rumbia is expected to veer northeast.However,the change of high-level environmental field factor on the northeast of Yagi is not noticeable,and Yagi is far away from the upper-level jet stream,which is not conducive to Yagi's northeast recurvature.