张旭, 黄伟, 陈葆德. 2015: 二阶精度半隐式半拉格朗日轨迹计算和时间积分方案在GRAPES区域模式中的应用. 气象学报, (3): 557-565. DOI: 10.11676/qxxb2015.023
引用本文: 张旭, 黄伟, 陈葆德. 2015: 二阶精度半隐式半拉格朗日轨迹计算和时间积分方案在GRAPES区域模式中的应用. 气象学报, (3): 557-565. DOI: 10.11676/qxxb2015.023
ZHANG Xu, HUANG Wei, CHEN Baode. 2015: Implementation of a 2nd order semi-implicit semi-Lagrangian trajectory algorithm and time integration scheme in the GRAPES regional model. Acta Meteorologica Sinica, (3): 557-565. DOI: 10.11676/qxxb2015.023
Citation: ZHANG Xu, HUANG Wei, CHEN Baode. 2015: Implementation of a 2nd order semi-implicit semi-Lagrangian trajectory algorithm and time integration scheme in the GRAPES regional model. Acta Meteorologica Sinica, (3): 557-565. DOI: 10.11676/qxxb2015.023

二阶精度半隐式半拉格朗日轨迹计算和时间积分方案在GRAPES区域模式中的应用

Implementation of a 2nd order semi-implicit semi-Lagrangian trajectory algorithm and time integration scheme in the GRAPES regional model

  • 摘要: 将两时间层稳定外插方案(Stable Extrapolation Two-Time-Level Scheme,SETTLS)引入GRAPES区域模式,并将其用于上游点和非线性项的时间外插计算。对线性项采用二阶精度的非中央权重时间平均,并取等温参考大气的温度大于实际大气平均温度,以保证半隐式积分方案的稳定性。原GRAPES时间积分方案对线性项做一阶非中央权重时间平均,对参考大气的选择并无限制,而为保证稳定性,须取较大的非中央权重系数,但非中央权重系数会对低波数波动产生较强的衰减作用。理想试验结果表明,相比原GRAPES半隐式半拉格朗日(SISL)时间积分方案,新SISL时间积分方案计算稳定且对波动的衰减作用较弱。

     

    Abstract: The Stable Extrapolation Two-Time-Level Scheme (SETTLS) has been implemented in the GRAPES regional model to determine the trajectory and nonlinear terms. To make the scheme stable, selecting a relatively warm reference temperature is necessary. The first-order decentered averaging of the linear terms of the previous version of the GRAPES relaxes the restriction of a relatively warm reference temperature but its large weight results in a significant damping for the low-wavenumber modes. Therefore, a second-order accuracy decentering of the linear terms and warmer reference temperature are applied in the GRAPES model. The results from the ideal experiments show that the new semi-implicit semi-Lagrangian scheme is stable and leads to much less damping than the original time integration scheme.

     

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