The mechanism analysis of the track deviation of tropical cyclone Megi (2010) simulated with two planetary boundary layer schemes

The WRF model was employed to conduct the simulations for super typhoon Megi (2010) with YSU and MYJ planetary boundary layer (PBL) scheme respectively. The sensitivity of the simulated tropical cyclone (TC) track to the PBL scheme was investigated, and the mechanism of the PBL scheme influencing TC track simulation from the viewpoint of TC scale was analyzed. The results show that the description of the vertical mixing process with different scheme causes the difference of simulated lower-level water vapor vertical transportation. Relative to the MYJ scheme, which can reproduce the Megi track well, the simulation with YSU scheme will make more active outer spiral rainbands and magnify TC size. Accordingly, the intensive outer pressure gradient and radial wind will make more air mass transportation from western Pacific subtropical high (WPSH) to TC, which will lead to the weakening of WPSH as well as the steering flow. As a result, the simulation with YSU scheme will cause TC turns northward ahead of time.