Sensitivity of Typhoon Lingling (2019) simulations to horizontal mixing length and planetary boundary layer parameterizations

• Published in: Frontiers of earth science Vol. 16; no. 2; pp. 304 - 322
• Main Authors: CHEN, Siqi, XU, Feng, ZHANG, Yu, YE, Guiling, XU, Jianjun, LIU, Chunlei
• Format: Journal Article
• Language: English
• Published: Beijing Higher Education Press 01.06.2022; Springer Nature B.V
• Subjects: Angular momentum; Bias; Boundary layer parameters; Boundary layers; Earth and Environmental Science; Earth Sciences; Eddies; Experiments; Fluid dynamics; fluid mechanics; Geophysical fluids; geophysics; Horizontal diffusion; Hurricane Weather Research and Forecasting model; Hurricanes; Hydrodynamics; Mathematical models; Mixing length; Momentum; Momentum budget; Numerical prediction; Numerical weather forecasting; Parameterization; Planetary boundary layer; Research Article; Sensitivity; Simulation; troposphere; typhoon; Typhoons; Vertical diffusion; Vortices; Weather forecasting; western Pacific; western Pacific; typhoon; Hurricane Weather Research and Forecasting model; horizontal diffusion; planetary boundary layer
• ISSN: 2095-0195; 2095-0209
• DOI: 10.1007/s11707-021-0890-0

Forecasting the intensity of typhoons is a difficult problem in numerical weather prediction. It is subject to many factors, among which the selection of physical parameterization schemes for the model is a hot topic of research. In this study, the effects of horizontal mixing length (represented by h_diff) and planetary boundary layer (PBL) schemes were investigated. Six idealized and four operational sensitivity experiments were designed based on simulation of the typhoon Lingling, which occurred over the western Pacific in 2019, using the Hurricane Weather Research and Forecasting model. The results of the idealized experiments showed that, as h_diff was increased, the slope of the typhoon eye area also increased, and its intensity becam e stronger. On the other hand, the results of the sensitivity experiments indicated that the intensity of the simulated typhoon was sensitive to the choice of PBL scheme, with the forecast bias of the QNSE (Quasi-Normal Scale Elimination) scheme being smaller than that of the GFDL (Geophysical Fluid Dynamics Laboratory) scheme. Angular momentum budget analyses indicated that, when increasing the h_diff, the convergence of angular momentum was larger in the boundary layer, which led to a faster spin-up of the vortex, further increasing the intensity of the typhoon. From the calculated horizontal and vertical vortex spread it was found that, when the h_diff was increased, the corresponding horizontal and vertical diffusion eddies also showed an increasing trend, which was also the reason for the strengthening of the typhoon. Meanwhile, the forecast bias decreased significantly with increasing horizontal mixing length when using the same PBL scheme.