A Fast Linear Semi-Lagrangian Advection Scheme Coupled with Spectral (bin) Microphysics to Simulate an Idealized Super Cell Storm in WRF
A Fast Linear Semi-Lagrangian Advection Scheme Coupled with Spectral (bin) Microphysics to Simulate an Idealized Super Cell Storm in WRF
复制标题
快速线性半拉格朗日平流方案与光谱（bin）微物理相结合，模拟 WRF 中的理想化超级细胞风暴
DOI：
10.1175/mwr-d-20-0244.1
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发表时间：
2021
影响因子：
3.2
通讯作者：
A. Khain
中科院分区：
文献类型：
--
作者：
B. Lynn;E. Gavze;J. Dudhia;D. Gill;A. Khain
采用一种新的、计算效率高的半拉格朗日平流（SLA）格式，利用WRF和谱（bin）微物理（SBM）耦合模拟了一场理想的超级单体风暴。SLA的开发是为了使复杂的微物理方案更易于云解析模型的计算访问。SLA是一阶半拉格朗日格式和二阶半拉格朗日格式的线性组合。它具有相对低的数值扩散，高水平的质量守恒精度，并保留多个平流变量的和。除理想化试验外，还与标准WRF高阶非线性平流方案进行了比较。使用不同的γ加权系数对一阶和二阶分量的组合进行了SLA测试。在1 km、500 m和250 m栅格上的模拟结果与WRF标准平流方案的模拟结果吻合较好，且与250 m栅格间距的模拟结果最为接近。同时，SLA方案所需的平流CPU时间比WRF方案短2.2 ~ 3倍。加速发生的部分原因是对所有水流星质量仓的平流使用了相同的平流矩阵。这项工作的发现支持了云微物理模拟对微物理的选择比对平流方案的选择更敏感的假设，从而证明了使用计算效率高的低阶线性方案是合理的。
A new, computationally efficient Semi-Lagrangian advection (SLA) scheme was used to simulate an idealized supercell storm using WRF coupled with Spectral (bin) Microphysics (SBM). SLA was developed to make complicated microphysical schemes more computationally accessible to cloud resolving models. The SLA is a linear combination of Semi-Lagrangian schemes of the first and the second order. It has relatively low numerical diffusion, a high level of mass conservation accuracy, and preserves the sum of multiple advected variables. In addition to idealized tests, comparisons were made with standard WRF higher-order, non-linear advection schemes. Tests of the SLA were performed using different weighting coefficients of γ for the combination of the first and second order components. The results of SLA on grids of 1 km, 500 m, and 250 m agree well with those of the standard WRF advection schemes, with results most similar to simulations with 250 m grid spacing. At the same time, the advection CPU time required by the SLA was 2.2 to 3 times shorter than the WRF advection schemes. The speed-up occurred in part because of the utilization of the same advection matrix for the advection of all hydrometeor mass bins. The findings of this work support the hypothesis that cloud microphysical simulation is more sensitive to the choice of microphysics than to the choice of advection schemes, thereby justifying the use of computationally efficient lower order linear schemes.