张红亮,沈学顺,苏勇. 2022. 预估-校正的半隐式半拉格朗日时间积分方案及其在CMA-GFS模式中的应用. 气象学报,80(2):280-288. DOI: 10.11676/qxxb2022.021
引用本文: 张红亮,沈学顺,苏勇. 2022. 预估-校正的半隐式半拉格朗日时间积分方案及其在CMA-GFS模式中的应用. 气象学报,80(2):280-288. DOI: 10.11676/qxxb2022.021
Zhang Hongliang, Shen Xueshun, Su Yong. 2022. A semi-implicit semi-Lagrangian time integration schemes with a predictor and a corrector and their applications in CMA-GFS. Acta Meteorologica Sinica, 80(2):280-288. DOI: 10.11676/qxxb2022.021
Citation: Zhang Hongliang, Shen Xueshun, Su Yong. 2022. A semi-implicit semi-Lagrangian time integration schemes with a predictor and a corrector and their applications in CMA-GFS. Acta Meteorologica Sinica, 80(2):280-288. DOI: 10.11676/qxxb2022.021

预估-校正的半隐式半拉格朗日时间积分方案及其在CMA-GFS模式中的应用

A semi-implicit semi-Lagrangian time integration schemes with a predictor and a corrector and their applications in CMA-GFS

  • 摘要: CMA-GFS采用的是传统的二时间层半隐式半拉格朗日时间积分方案(SISL)。拉格朗日平流速度和非线性项需要采用时间外插进行计算,在急流轴附近等梯度大值区会造成计算不稳定,甚至积分中断现象。文中通过构造预估-校正半隐式半拉格朗日时间积分方案(SISL/P-C),以减少时间外插的影响;半隐式系数由原来的0.72减小到0.55,构造准二阶精度的时间积分方案。理想试验和实际资料试验证明新方案可以改善CMA-GFS的精确度、稳定性和质量守恒。0.25°水平分辨率下积分时间步长可以由300 s 增大到450 s,模式总体计算效率提高20%。

     

    Abstract: A classical two-time level semi-implicit semi-Lagrange scheme (SISL) is used in CMA-GFS. Lagrange advection velocity and nonlinear terms are calculated by temporal extrapolation, which can cause computational instability and even integration interruption in large gradient areas such as the areas of jet. A SISL/P-C (predictor-corrector) algorithm is developed in CMA-GFS to reduce the impact of temporal extrapolation and construct a quasi-second order precision time discretization scheme by reducing the semi-implicit coefficients from 0.72 to 0.55. Results of idealized and real-data experiments show that this new scheme can effectively improve forecast accuracy, stability and conservation. The integration time step can be increased from 300 s to 450 s at 0.25° horizontal resolution, and the model calculation efficiency can be increased by 20%.

     

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