ISSN 1006-9895

CN 11-1768/O4

Numerical Investigation of the Effects of Boundary Layer Parameterization Schemes on Typhoon Meranti (1614) Landing Process
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Laboratory of Straits Meteorology,Xiamen Meteorological Bureau

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    Abstract:

    A serious of high-resolution (1.33 km) numerical tests have been done by means of seven boundary layer parameterization schemes in mesoscale numerical model WRF v3.8, namely YSU, MYJ, QNSE, ACM2, UW, GBM, and Boulac, in order to study the effects of different boundary layer schemes on the simulation of landing attenuation stage of Typhoon Meranti (1614) in terms of movement track, intensity, structure, rainfall, and near-surface physical variables. The results indicate that: (1) boundary layer schemes influenced significantly simulation of Typhoon Meranti’s track, intensity, and rainfall during its landing attenuation stage, and the maximum differences in 24-h simulated typhoon track, the lowest atmospheric pressure, the maximum wind velocity, and 24-h cumulative rainfall extremum were 80 km, 11 hPa, 27 m s-1, and 241 mm, respectively. (2) simulation by Boulac scheme resulted in a typhoon track closest to real-time result, followed by GBM, YSU, and MYJ schemes, and then by ACM2 and UW schemes, while QNSE scheme had the worst simulation; lowest atmospheric pressure values simulated by UW and QNSE schemes, and values of the maximum wind velocity simulated by schemes MYJ and QNSE are closest to corresponding observations; all boundary layer schemes simulated features of the typhoon that the lowest atmospheric pressure increased gradually during landing stage and rate of such increase after landing was greater than that before landing, which agreed with real-time results, but increasing rate of the lowest atmospheric pressure before typhoon landing simulated by each scheme was greater than the real-time result, while such increasing rate after typhoon landing simulated by each scheme was less than the real-time result. (3) Boulac scheme is the best in the simulation of 24-h precipitation distribution, heavy precipitation area, structure, intensity, and TS score of precipitation at each level, and MYJ scheme is the second best; as simulated by QNSE, UW and ACM2 schemes, the rain belt advanced so quickly northwestward that TS scores of precipitation at various levels were poor. (4) in overall simulation of track, intensity and precipitation of the typhoon, Boulac and MYJ schemes were optimal, among which, Boulac scheme was superior in simulation of typhoon track and precipitation while MYJ scheme was superior in simulation of typhoon intensity; YSU and GBM scheme had the second best simulation results, whereas QNSE, UW and ACM2 schemes had worse simulation performance. (5) boundary layer schemes differed significantly in calculated latent heat flux and sensible heat flux of near-surface layer, thereby simulation of typhoon track, intensity and rainfall was affected, leading to significantly different simulation results. In comparison, QNSE scheme resulted in an abnormally high latent heat flux, MYJ and Boulac schemes resulted in the most modest values, and other schemes resulted in slightly smaller values; QNSE scheme had a slightly higher sensible heat flux, MYJ scheme had the most modest one, and other schemes resulted in significantly smaller values. (6) boundary layer schemes differed significantly in simulated thermal and dynamical structure of boundary layer and Boulac scheme had the obvious advantages, especially for the structure of boundary layer in daytime.

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History
  • Received:March 26,2019
  • Revised:November 21,2019
  • Adopted:April 27,2020
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