数值模式垂直分辨率对台风大涡模拟的影响

The effect of vertical resolution on the large-eddy simulation of idealized tropical cyclone

随着计算能力的提升,台风数值模拟大量采用了大涡尺度模拟,其水平分辨率已达到数10 m的量级,而垂直分辨率提升不大,其问题是数值模式的垂直分辨率对台风大涡模拟的影响如何?因此,本文利用WRF(Weather Research and Forecasting)模式开展理想台风模拟,在不同的模式垂直层次(42,69和90层)情况下,研究并讨论数值模式垂直分辨率对台风大涡模拟的影响。结果表明,42层的垂直分辨率明显不足,而69层和90层的垂直分辨率则都能模拟出细致的台风边界层小尺度结构,龙卷尺度涡旋出现较多。与69层试验相比,90层试验模拟的台风强度要弱、龙卷尺度涡旋数量要少,但模拟的台风强度更稳定,模拟的小尺度涡旋也更精细。

With the improvement of computing power, the numerical simulation of Tropical Cyclone(TC) has adopted a large number of Large-eddy Simulations(LES), and its horizontal resolution has reached the order of 10 m, while the vertical resolution of the numerical model has not improved much. The question is how does the vertical resolution of the numerical model affect the Tropical Cyclone Large-eddy Simulation(TC-LES) In this study, idealized Tropical Cyclone simulations are carried out using the WRF(Weather Research and Forecasting) model. To discuss the effect of vertical resolution on TC-LES with 42, 69 and 90 model vertical levels. It is found that the vertical resolution of 42 levels is clearly inadequate, while the vertical resolution of both 69 and 90 levels can simulate detailed TC small-scale organized structure of the boundary layer, with more tornado-scale vortices appearing. Compared with the N69 experiment, the N90 experiment simulates weaker TC and fewer tornado-scale vortices. But the simulated TC intensity is more stable and the simulated small-scale vortices are more detailed.