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

作　　者：张旭[1,2] 黄伟[1,2] 陈葆德[1,2] 

机构地区：[1]中国气象局台风数值预报重点实验室,上海200030 [2]中国气象局上海台风研究所,上海200030

出　　处：《气象学报》2015年第3期557-565,共9页Acta Meteorologica Sinica

基　　金：国家公益性行业(气象)科研专项(GYHY201206006)

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。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 restric-tion 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.

关 键 词：两时间层稳定外插方案(SETTLS) 半隐式半拉格朗日(SISL)时间积分 上游点计算 衰减作用 参考大气温度 

分 类 号：P435[天文地球—大气科学及气象学]