Characteristics of extreme rainfall and rainbands evolution of Super Typhoon Lekima (2019) during its landfall

As one of the most devastating tropical cyclones over the western North Pacific Ocean,Super Typhoon Lekima(2019)has caused a wide range of heavy rainfall in China.Based on the CMA Multi-source merged Precipitation Analysis System(CMPAS)-hourly data set,both the temporal and spatial distribution of extreme rainfall is analyzed.It is found that the heavy rainfall associated with Lekima includes three main episodes with peaks at 3,14 and 24 h after landfall,respectively.The first two rainfall episodes are related to the symmetric outburst of the inner rainband and the persistence of outer rainband.The third rainfall episode is caused by the influence of cold,dry air from higher latitudes and the peripheral circulation of the warm moist tropical storm.The averaged rainrate of inner rainbands underwent an obvious outburst within 6 h after landfall.The asymmetric component of the inner rainbands experienced a transport from North(West)quadrant to East(South)quadrant after landfall which was related to the storm motion other than the Vertical Wind Shear(VWS).Meanwhile the outer rainband in the vicinity of three times of the Radius of Maximum Wind(RMW)was active over a 12-h period since the decay of the inner rainband.The asymmetric component of the outer rainband experienced two significant cyclonical migrations in the northern semicircle.

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.