NUMERICAL STUDIES OF PLANETARY BOUNDARY LAYER PARAMETERIZATION SCHEMES ON SUPER TYPHOON SANBA (2012) DURING ITS INITIAL STAGE

Abstract:

The formation and development of typhoons are closely related to the disturbed low vortexes at the planetary boundary layer (PBL). The effects of five PBL parameterization schemes (PBL schemes hereinafter) on the trajectory, intensity, and distribution of physical quantities are studied using the mesoscale WRF model on Super Typhoon Sanba (2012) during its initial stage. Results show that the five PBL schemes exhibit significant different effects on the simulated intensity and path. The results simulated by QNSE and ACM2 without the Bogus method are close to the best track data in the numerical experiments. When the Bogus method is adopted, the simulated trajectories improve significantly because the initial field is close to the true data. Among the five PBL schemes, QNSE and ACM2 with the Bogus method present improved simulated path and intensity compared with the three other schemes. This finding indicates that the two schemes deal with the initial PBL process satisfactorily, especially in the formation and development of disturbed low vortexes. The differences in the treatment methods of the five PBL schemes affect the surface layer physical quantities and the middle and upper atmospheres during the middle to late periods of the typhoon. Although QNSE and ACM2 present better simulation results than other schemes, they exhibit a few differences in the internal structure of the typhoon. The results simulated by MYJ are worse, and this method may be unsuitable for studying the formation and development of typhoons.