CAJ | 학술논문

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。
상시용일개기우유한차분적량보보형평류방안（TSPAS）체대미국국가대기연구중심제5판공용대기모식（NCAR-CAM5）구랍-보동력광가중적반랍격랑일전수（SLT）평류방안，병침대불동분변솔판본，계산수기등물질적전수과정。통과설계보증수항성적도점차분법，해결료기우경위망격적모식재고분변솔하유우겁구위향격거과소이조성적차분방안적분시간보장과단적문제，사득TSPAS재고분변솔하잉연가이사용교대적시간보장。이상시험표명：（1）도점TSPAS재수항성、수치정도（량급상）、보형성등방면균교호지보지료원TSPAS적특점，이적분보장가증대도여CAM5-SLT상동，비원TSPAS제고초과일개수량급；（2）교반랍격랑일전수방안，진관TSPAS적모산경대，단시재상동시간보장하경성시，차개진료반랍격랑일전수구해평류방정조성적불수항문제。CAM5적비교시험표명：（1）채용도점TSPAS적모식결과여비도점계산결과상당，재고위도도점구역야병미출현모의이상；（2）재고분변솔하，채용도점TSPAS방안적CAM5모의결과여원모식결과상근，병초보현시대동아청장고원남측적허가강수유소억제。해공작학보료기우구랍통량차분형적TSPAS재고분변솔모식하적대시간보장은정적분，위해결유한차분방법재고분변솔모식발전중적상관계산문제제공료계시，위후속침대동아지구적모식성능개진전정료기출。
A finite difference based Two-step Shape Preserving Advection Scheme (TSPAS)was ported into an Eulerian-Spec-tral dynamical core of National Center for Atmospheric Research (NCAR)-Community Atmospheric Model 5 (CAM5 ),to re-place 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 sol-id body rotation tests suggest:(1 )the leaping-point TSPAS maintains the conservation,shape-preserving and numerical preci-sion 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 sim-ulation 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 differ-ence based advection scheme in a high-resolution model and lays a basis for improving model performance in East Asia.