2.3 Back-trajectory analyses
The HYSPLIT model (NOAA, https://www.ready.noaa.gov/HYSPLIT_traj.php)
was developed to calculate and analysis the transport trajectory of
atmospheric pollution or water vapor towards or from a set location
(Stein et al., 2015). The atmospheric air masses of precipitation were
simulated by a back-trajectory analysis, and the NCEP Global Data
Assimilation System (GDAS) database was selected for each
back-trajectory of 72 h. Normally, convective activity raise the
typhoons to greater heights. Hence, the starting heights of water vapor
trajectories were taken to be 500, 1000, and 2000 m above mean sea
level.