Endpoints of backward trajectories starting from Tiantai (TT), Fengxian (FX) and Yixing (YX) during Sept. 10–13.

<p>Note: (i) The endpoints with blue fill color started from Tiantai, those with green fill color started from Fengxian and those with red fill color started from Yixing. (ii)The endpoints in square (▪): the migration duration was less than 13 h, and takes off at 1800 h on the same day; in triangle (▴): the migration duration was 13–24 h, and takes off at 1800 h on the previous day. (•): the migration duration was above 24 h, and takes off at 1800 h on the previous day.