张祎,宇如聪,李建,陈昊明. 2013. 两步保形平流方案在高分辨率球面经纬网格下的跳点差分试验[J]. 气象学报, 71(6):1089-1102, doi:10.11676/qxxb2013.085
两步保形平流方案在高分辨率球面经纬网格下的跳点差分试验
An implementation of a leaping-point Two-step Shape-Preserving Advection Scheme in the high-resolution spherical latitude-longitude grid
投稿时间:2013-03-25  修订日期:2013-06-24
DOI:10.11676/qxxb2013.085
中文关键词:  跳点差分  两步保形平流方案  半拉格朗日传输  CAM5  高分辨率模式
英文关键词:Leaping-point difference  TSPAS  Semi-Lagrangian transport  CAM5  High-resolution model
基金项目:高分辨率气候系统模式的研制与评估(2010CB951900)。
作者单位E-mail
张祎 中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点试验室, 北京, 100029
中国科学院大学, 北京, 100049 
 
宇如聪 中国气象局, 中国气象科学研究院灾害天气国家重点试验室, 北京, 100081 yrc@cma.gov.cn 
李建 中国气象局, 中国气象科学研究院灾害天气国家重点试验室, 北京, 100081  
陈昊明 中国气象局, 中国气象科学研究院灾害天气国家重点试验室, 北京, 100081  
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中文摘要:
      尝试用一个基于有限差分的两步保形平流方案(TSPAS)替代美国国家大气研究中心第5版公用大气模式(NCAR-CAM5)欧拉-谱动力框架中的半拉格朗日传输(SLT)平流方案,并针对不同分辨率版本,计算水汽等物质的传输过程。通过设计保证守恒性的跳点差分法,解决了基于经纬网格的模式在高分辨率下由于极区纬向格距过小而造成的差分方案积分时间步长过短的问题,使得TSPAS在高分辨率下仍然可以使用较大的时间步长。理想试验表明:(1)跳点TSPAS在守恒性、数值精度(量级上)、保形性等方面均较好地保持了原TSPAS的特点,而积分步长可增大到与CAM5-SLT相同,比原TSPAS提高超过一个数量级;(2)较半拉格朗日传输方案,尽管TSPAS的耗散更大,但是在相同时间步长下更省时,且改进了半拉格朗日传输求解平流方程造成的不守恒问题。CAM5的比较试验表明:(1)采用跳点TSPAS的模式结果与非跳点计算结果相当,在高纬度跳点区域也并未出现模拟异常;(2)在高分辨率下,采用跳点TSPAS方案的CAM5模拟结果与原模式结果相近,并初步显示对东亚青藏高原南侧的虚假降水有所抑制。该工作确保了基于欧拉通量差分型的TSPAS在高分辨率模式下的大时间步长稳定积分,为解决有限差分方法在高分辨率模式发展中的相关计算问题提供了启示,为后续针对东亚地区的模式性能改进奠定了基础。
英文摘要:
      A finite difference based Two-step Shape Preserving Advection Scheme (TSPAS) was ported into an Eulerian-Spectral dynamical core of National Center for Atmospheric Research (NCAR)-Community Atmospheric Model 5 (CAM5), to replace the original Semi-Lagrangian Transport (SLT) scheme for resolving the advection equation under different resolutions. A leaping-point TSPAS is designed to increase the time-step which is too short as limited by the extremely high zonal resolution in the high-latitude regions of a high-resolution model. The TSPAS can thus, accommodate to large time-step. The results of solid body rotation tests suggest: (1) the leaping-point TSPAS maintains the conservation, shape-preserving and numerical precision of the original TSPAS, but with a large increase on time-step; (2) although the numerical diffusion is larger in the TSPAS than that in the SLT, the TSPAS run is less time consuming and improves the conservation of the transported scalar. The simulation in CAM5 suggests: (1) the results are similar in leaping-point and original TSPAS runs, and there is no anomaly in high-latitude regions; (2) in high-resolution simulation, CAM5-TSPAS and CAM5-SLT also exhibit similar results, but CAM5-TSPAS shows an improvement of precipitation in the southern side of the Tibetan Plateau. This work ensures a stable large-time-step integration of CAM5-TSPAS in its high-resolution simulation, presents an enlightenment for using finite difference based advection scheme in a high-resolution model and lays a basis for improving model performance in East Asia.
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